Background/Objectives: Understanding food preferences is important for weight management. However, methods for assessing food preferences are not well established, especially in Japan. This study aimed to examine detailed food preferences and their associations with actual food intake in non-obese and abdominal-obese subjects using a newly developed questionnaire tailored for the Japanese population. Methods: We developed the Japan Food Preference Questionnaire (JFPQ) to evaluate food preferences across four nutrient groups based on nutritional evidence: carbohydrate, fat, protein, and dietary fiber. A total of 38 non-obese and 30 abdominal-obese participants completed both the JFPQ and the Food Frequency Questionnaire (FFQ). Food preferences for each nutrient were compared between the two groups, and correlations between food preferences (assessed by the JFPQ) and food intake (assessed by the FFQ) were analyzed. Results: Compared with the non-obese group, the abdominal-obese group showed significantly greater preferences for carbohydrates, fat, and protein, with no significant difference in dietary fiber after adjusting for age and sex. Furthermore, in the abdominal-obese group, positive correlations were found between actual intake and preference for high-fat and high-carbohydrate foods. Conclusions: Our findings from this pilot study demonstrated that abdominal-obese individuals had greater preferences for fat and carbohydrates, which were linked to actual fat and carbohydrate intake and possibly contributed to the development of obesity.

(1) Background: The number of severely obese patients worldwide is rapidly increasing. Recently, novel therapeutic approaches, such as bariatric surgery or GLP-1 receptor agonists, have emerged, bringing about a paradigm shift in this field. However, these therapies sometimes face challenges, such as peri-surgical complications or supply shortages. Mazindol, which is an appetite suppressant approved decades ago in Japan, remains a valuable option. In this study, we investigated the effectiveness of mazindol in reducing body weight in 147 patients, and we examined the factors influencing said effectiveness. (2) Methods: The patients were divided into four groups based on the treatment cycles they underwent: 1 cycle, 2 cycles, 3–5 cycles, and over 6 cycles. We compared the changes in body weight before and after the treatment among these four groups. Additionally, we sought to identify the factors correlated to the effectiveness of mazindol. (3) Results: The change in body weight was more pronounced in the group which underwent 3–5 cycles compared to the groups which underwent 1 cycle and 2 cycles; this change was also more pronounced in the group which underwent over 6 cycles compared to those which underwent 1 cycle. Furthermore, we observed a significant correlation between the initial body weight and the extent of body weight change. (4) Conclusions: Mazindol demonstrated effectiveness in reducing the body weight of patients in a cycle-dependent manner.

Abstract Continuous glucose monitoring (CGM) values obtained from CGM systems using the same sensor but with different internal algorithms (the first- and third-generation FreeStyle Libre (1st-gen-libre and 3rd-gen-libre, respectively)) were compared. We used 19,819 paired and simultaneously measured CGM values of 13 patients with diabetes. The average CGM value was significantly higher (P < 0.0001) and the time below range (CGM value < 70 mg/dL) was significantly lower (P < 0.0001) with the 3rd-gen-libre than with the 1st-gen-libre. There was a significant correlation (P < 0.0001) between the CGM values of the 3rd-gen-libre (y-axis, mg/dL) and 1st-gen-libre (x-axis, mg/dL) using the following formula: y = 0.9728x + 10.024. On assessing the association between glycated hemoglobin (HbA1c (%), y-axis) and the average CGM values (x-axis, mg/dL) by applying the obtained equation to previously reported 1st-gen-libre data and converting it to 3rd-gen-libre data, we obtained the equation y = 0.02628x + 3.233, indicating that the glucose management indicator reported in the West may be underestimated compared with the laboratory-measured HbA1c in the Japanese population. Glucose values from the same sensor were found to be significantly different between readers with different algorithms, and the calculation of CGM-related indices may need to be individualized for each device.

Abstract Context Glucose tolerance worsens after distal pancreatectomy (DP); however, the long-term incidence and factors affecting interindividual variation in this worsening are unclear. Objective To investigate the changes in diabetes-related traits before and after DP and to clarify the incidence of diabetes and its predictors. Methods Among 493 registered patients, 117 underwent DP. Among these, 56 patients without diabetes before surgery were included in the study. Glucose and endocrine function were prospectively assessed using a 75-g oral glucose tolerance test preoperatively, 1 month after DP, and every 6 months thereafter for up to 36 months. Pancreatic volumetry was performed using multidetector row computed tomography before and after surgery. Results Insulin secretion decreased and blood glucose levels worsened after DP. Residual pancreatic volume was significantly associated with the reserve capacity of insulin secretion but not with blood glucose levels or the development of diabetes. Among 56 patients, 33 developed diabetes mellitus. The cumulative incidence of diabetes at 36 months after DP was 74.1%. Multivariate Cox regression analysis showed that impaired glucose tolerance as a preoperative factor as well as a decreased insulinogenic index and impaired glucose tolerance at 1 month postoperatively were identified as risk factors for diabetes following DP. Conclusion Impaired glucose tolerance and reduced early-phase insulin response to glucose are involved in the development of new-onset diabetes after DP; the latter is an additional factor in the development of diabetes and becomes apparent when pancreatic beta cell mass is reduced after DP.

BACKGROUND: Ectopic fat is fat that accumulates in or around specific organs or compartments of the body including myocardium. The clinical features of type 2 diabetes patients with high fat accumulation in the myocardium remain unknown. Moreover, little is known about the influence of myocardial fat accumulation in type 2 diabetes on coronary artery disease and cardiac dysfunction. We aimed to clarify the clinical features, including cardiac functions, of type 2 diabetes patients with myocardial fat accumulation. METHODS: We retrospectively enrolled type 2 diabetes patients who underwent ECG-gated coronary computed tomography angiography (CCTA) and abdominal computed tomography (CT) scan examinations within 1 year of CCTA from January 2000 to March 2021. High fat accumulation in the myocardium was defined as the low mean myocardial CT value of three regions of interest, and the associations between CT values and clinical characteristics or cardiac functions were assessed. RESULTS: In total, 124 patients were enrolled (72 males and 52 females). The mean age was 66.6 years, the mean BMI was 26.2 kg/m2, the mean ejection fraction (EF) was 67.6%, and the mean myocardial CT value was 47.7 Hounsfield unit. A significant positive correlation was found between myocardial CT value and EF (r = 0.3644, p = 0.0004). The multiple regression analyses also showed that myocardial CT value was independently associated with EF (estimate, 0.304; 95% confidence interval (CI) 0.092 to 0.517; p = 0.0056). Myocardial CT value showed significant negative correlations with BMI, visceral fat area and subcutaneous fat area (r = - 0.1923, - 0.2654, and -0.3569, respectively, p < 0.05). In patients who were ≥ 65 years or female, myocardial CT value showed significant positive correlations with not only EF (r = 0.3542 and 0.4085, respectively, p < 0.01) but also early lateral annular tissue Doppler velocity (Lat e') (r = 0.5148 and 0.5361, respectively, p < 0.05). The multiple regression analyses showed that myocardial CT value was independently associated with EF and Lat e' in these subgroups (p < 0.05). CONCLUSIONS: Patients with type 2 diabetes, especially in elderly or female patients, who had more myocardial fat had more severe left ventricular systolic and diastolic dysfunctions. Reducing myocardial fat accumulation may be a therapeutic target for type 2 diabetes patients.

Background: The effects of uric acid (UA)-lowering therapy with xanthine oxidoreductase (XOR) inhibitors on the development of cardiovascular diseases remain controversial. Based on recent findings that plasma XOR activity increased in liver disease conditions, we conducted a sub-analysis of the BEYOND-UA study to examine the differential effects of topiroxostat on arterial stiffness based on liver function in hyperuricemic individuals with hypertension. Methods: Sixty-three subjects treated with topiroxostat were grouped according to baseline alanine aminotransferase (ALT) levels (above or below cut-off values of 22, 30, or 40 U/L). The primary endpoint was changes in the cardio-ankle vascular index (CAVI) from baseline to 24 weeks. Results: Significant reductions in CAVI during topiroxostat therapy occurred in subjects with baseline ALT ≥30 U/L or ≥40 U/L, and significant between-group differences were detected. Brachial-ankle pulse wave velocity significantly decreased in the ALT-high groups at all cut-off values. Reductions in morning home blood pressure and serum UA were similar regardless of the baseline ALT level. For eleven subjects with available data, ALT-high groups showed high plasma XOR activity, which was significantly suppressed by topiroxostat. Conclusions: Topiroxostat improved arterial stiffness parameters in hyperuricemic patients with liver dysfunction, which might be related to its inhibitory effect on plasma XOR.

Background: Metabolic and bariatric surgery (MBS) has been established to provide long-term weight loss in severe obesity. In this study, we investigated the factors that affect post-operative weight loss, with a particular focus on changes in eating behaviors. Methods: Time-course changes in body weight and eating behaviors were examined in 49 Japanese patients who underwent laparoscopic sleeve gastrectomy from the first visit to 12 months after surgery. Each eating behavior was evaluated via the questionnaire of the Japan Society for the Study of Obesity. Results: Pre-operative weight reduction mediated by dietary and lifestyle interventions showed significant positive correlations with weight loss outcomes at 12 months after surgery. We observed significant decreases in scores for most of the eating behaviors 12 months after surgery. However, “emotional eating behavior” scores declined temporarily in the early post-operative period of one month but thereafter returned to the pre-operative level at 12 months. Furthermore, increases in the scores for “emotional eating behavior” and “sense of hunger” from 1 to 12 months post-operatively were significantly associated with poor weight loss. Conclusions: Our results demonstrate the beneficial effects of MBS on obesity-related eating behaviors, as well as highlighting “emotional eating behavior” as requiring particular attention.

Endogenous humoral factors that link systemic and/or local insulin demand to pancreatic β-cells have not been identified. Here, we demonstrated that T-cadherin, a unique glycosylphosphatidylinositol-anchored cadherin primarily expressed in vascular endothelial cells and cardiac and skeletal muscle cells, but not in pancreatic β-cells, was secreted as soluble forms and was important for β-cell proliferation. Cdh13 (T-cadherin) knockout mice exhibited impaired glucose handling due to attenuated β-cell proliferation under high-fat diet conditions. The gene expression analyses indicated the impairment in cell cycle and Notch signaling in the islets of T-cadherin knockout mice under high-fat diet conditions. In streptozotocin-induced diabetes, the replacement of soluble T-cadherin improved β-cell mass and blood glucose levels in T-cadherin knockout mice. Recombinant soluble T-cadherin upregulated Notch signaling in cultured murine islets. We concluded that soluble T-cadherin could work as an endogenous humoral factor whose signaling pathways including Notch signaling regulate β-cell proliferation under diabetic conditions in mice.

Hypertriglyceridemia is caused not only by environmental factors but also by genetic factors. Severe hypertriglyceridemia is prone to complications of acute pancreatitis. Here, we report a whole-exome sequencing (WES) analysis for a young hypertriglyceridemic patient with recurrent acute pancreatitis and the patient's mother. A 28-year-old hypertriglyceridemic female was admitted to our hospital. At 23 years old, a health checkup clarified her hypertriglyceridemia. At the age of 26 and 27, she had repeated acute pancreatitis with severe hypertriglyceridemia (serum triglyceride level were 3,888 mg/dL and 12,080 mg/dL, respectively). The patient's BMI was 29.0 kg/m2, and blood samples under fibrate medication showed triglyceride 451 mg/dL and HbA1c 7.2%. Type V dyslipidemia became more apparent at postprandial state. The WES analysis showed that the patients had two heterozygous variants in Apolipoprotein A5 (APOA5) gene (p.G185C and p.V153M), a heterozygous variant in Apolipoprotein E (APOE) gene (p.R176C), three heterozygous variants in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene (p.T1220I, p.R1453W and p.V470M). On the other hand, her mother, who had moderate hypertriglyceridemia without acute pancreatitis, had a heterozygous variant in APOA5 gene (p.G185C) and two heterozygous variants in CFTR gene (p.T1220I and p.V470M). These results suggest that the more severe pathology of the patient than her mother might be due to the possible compound heterozygous APOA5 variants, the heterozygous APOE variant, and the possible compound heterozygous CFTR variants. In this case, WES analyses were useful to evaluate not only the causative genes of hypertriglyceridemia (APOA5 and APOE) but also the genes involved in the development of acute pancreatitis (CFTR) simultaneously.

Adiponectin (APN), a major adipokine secreted from white adipose tissue, prevents inflammation and improves insulin sensitivity. APN exists as distinct multimeric complexes with different physiological activities, including low, middle and high molecular weight complexes (LMW, MMW and HMW, respectively) in peripheral blood. Caloric restriction (CR), an intervention that suppresses aging-related pathophysiological changes and extends lifespan, reportedly elevates the expression levels of Adipoq (encoding APN) and total circulating APN. Circulating APN levels have generally been measured using ELISA, but ELISA fails to directly and separately detect APN multimeric complexes other than HMW. Here, we aimed to evaluate the association of aging and CR with oligomerization of APN in rodent models, using immunoblotting to distinguish multimeric complexes based on molecular sizes. In mice, aging elevated plasma levels of HMW and MMW, while CR only elevated HMW. In contrast, LMW and monomeric APN levels were unchanged, suggesting that aging and CR can induce the assembly of APN oligomers in adipocytes. In rats, plasma levels of all multimeric complexes and monomeric APN were not significantly changed by aging or CR. Collectively, levels of circulating APN in mice were consistent with previous findings, whereas those of rats were partially inconsistent, probably because of experimental differences. Moreover, aging reduced Adipoq mRNA levels in mice and rats, while CR prevented this reduction only in rats. Such a discrepancy between Adipoq expression and circulating APN levels may be attributed to proteasomal regulation in adipocytes or tissue accumulation of APN. In conclusion, this study provides new findings of aging- and CR-related changes of each APN multimeric complex and underscores the importance of qualitative approaches for a greater understanding of physiological changes in APN.

AIMS/HYPOTHESIS: Immunomodulators blocking cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) or programmed death-ligand 1 (PD-L1) have improved the treatment of a broad spectrum of cancers. These immune checkpoint inhibitors (ICIs) reactivate the immune system against tumour cells but can also trigger autoimmune side effects, including type 1 diabetes. Mesenchymal stem cell (MSC) therapy is the most prevalent cell therapy, with tissue-regenerating, anti-fibrosis and immunomodulatory functions provided by the secretome of the cells. Here, we examined whether systemic MSC treatment could prevent the development of type 1 diabetes in a NOD mouse model. METHODS: The purified PD-L1 monoclonal antibody was administered to induce diabetes in male NOD mice which normally do not develop diabetes. Human adipose-derived MSCs were administered by tail vein injections. T cells, macrophages and monocyte-derived macrophages expressing C-X-C motif chemokine ligand 9 (CXCL9) in pancreatic sections of NOD mice and a cancer patient who developed diabetes following the ICI treatments were analysed by immunofluorescence. Tissue localisation of the injected MSCs, plasma exosome levels and plasma cytokine profiles were also investigated. RESULTS: PD-1/PD-L1 blockade induced diabetes in 16 of 25 (64%) NOD mice which received anti-PD-L1 mAb without hMSCs [MSC(-)], whereas MSC administration decreased the incidence to four of 21 (19%) NOD mice which received anti-PD-L1 mAb and hMSCs [MSC(+)]. The PD-1/PD-L1 blockade significantly increased the area of CD3-positive T cells (6.2-fold) and macrophage-2 (Mac-2) antigen (2.5-fold)- and CXCL9 (40.3-fold)-positive macrophages in the islets. MSCs significantly reduced T cell (45%) and CXCL9-positive macrophage (67%) accumulation in the islets and the occurrence of diabetes. The insulin content (1.9-fold) and islet beta cell area (2.7-fold) were also improved by MSCs. T cells and CXCL9-positive macrophages infiltrated into the intricate gaps between the beta cells in the islets by PD-1/PD-L1 blockade. Such immune cell infiltration was largely prevented by MSCs. The most striking difference was observed in the CXCL9-positive macrophages, which normally did not reside in the beta cell region in the islets but abundantly accumulated in this area after PD-1/PD-L1 blockade and were prevented by MSCs. The CXCL9-positive macrophages were also observed in the islets of a cancer patient who developed diabetes following the administration of ICIs but few CXCL9-positive macrophages were observed in a control patient. Mechanistically, the injected MSCs accumulated in the lung but not in the pancreas and strongly increased plasma exosome levels and changed plasma cytokine profiles. CONCLUSIONS/INTERPRETATION: Our results suggest that MSCs can prevent the incidence of diabetes associated with immune checkpoint cancer therapy and may be worth further consideration for new adjuvant cell therapy.

BACKGROUND: Patients with diabetes are at a higher risk for cognitive decline. Thus, biomarkers that can provide early and simple detection of cognitive decline are required. Neurofilament light chain (NfL) is a cytoskeletal protein that constitutes neural axons. Plasma NfL levels are elevated when neurodegeneration occurs. Here, we investigated whether plasma NfL levels were associated with cognitive decline in patients with type 2 diabetes. METHOD: This study included 183 patients with type 2 diabetes who visited Osaka University Hospital. All participants were tested for cognitive function using the Mini-Mental State Examination (MMSE) and the Rivermead Behavioural Memory Test (RBMT). NfL levels were analysed in the plasma and the relationship between NfL and cognitive function was examined. RESULTS: Lower RBMT-standardized profile scores (SPS) or MMSE scores correlated with higher plasma NfL levels (one-way analysis of variance: MMSE, P = 0.0237; RBMT-SPS, P = 0.0001). Furthermore, plasma NfL levels (β = -0.34, P = 0.0005) and age (β = -0.19, P = 0.016) were significantly associated with the RBMT score after multivariable regression adjustment. CONCLUSIONS: Plasma NfL levels were correlated with mild cognitive decline which is detected by the RBMT but not the MMSE in patients with type 2 diabetes. This suggests that plasma NfL levels may provide a valuable clinical tool for identifying mild cognitive decline in patients with diabetes.

Hyperuricemia is caused by reduced renal/extrarenal excretion and overproduction of uric acid. It is affected by genetic predisposition related to uric acid transporters and by visceral fat accumulation due to overnutrition. The typical symptomatic complication of hyperuricemia is gout caused by monosodium urate crystals. Accumulated evidence from epidemiological studies suggests that hyperuricemia is also a risk factor for hypertension, chronic kidney disease (CKD) and atherosclerotic cardiovascular disease (CVD). However, it remains to be determined whether urate-lowering therapy for asymptomatic patients with hyperuricemia is effective in preventing CKD or CVD progression. This mini review focuses mainly on recent papers investigating the relationship between hyperuricemia and CKD or CVD and studies of urate-lowering therapy. Accumulated studies have proposed mechanisms of renal damage and atherosclerosis in hyperuricemia, including inflammasome activation, decreased nitric oxide bioavailability and oxidative stress induced by uric acid, urate crystals and xanthine oxidoreductase (XOR)-mediated reactive oxygen species. Since patients with hyperuricemia are a heterogeneous population with complex pathologies, it may be important to assess whether an outcome is the result of decreasing serum uric acid levels or an inhibitory effect on XOR. To clarify the impact of hyperuricemia on CKD and CVD progression, high-quality and detailed clinical and basic science studies of hyperuricemia and purine metabolism are needed.

Adiponectin (APN), a protein abundantly secreted from adipocytes, has been reported to possess beneficial effects on cardiovascular diseases in association with its accumulation on target organs and cells by binding to T-cadherin. However, little is known about the role of APN in the development of diabetic microvascular complications, such as diabetic retinopathy (DR). Here we investigated the impact of APN on the progression of early retinal vascular damage using a streptozotocin (STZ)-induced diabetic mouse model. Our immunofluorescence results clearly showed T-cadherin-dependent localization of APN in the vascular endothelium of retinal arterioles, which was progressively decreased during the course of diabetes. Such reduction of retinal APN accompanied the early features of DR, represented by increased vascular permeability, and was prevented by glucose-lowering therapy with dapagliflozin, a selective sodium-glucose co-transporter 2 inhibitor. In addition, APN deficiency resulted in severe vascular permeability under relatively short-term hyperglycemia, together with a significant increase in vascular cellular adhesion molecule-1 (VCAM-1) and a reduction in claudin-5 in the retinal endothelium. The present study demonstrated a possible protective role of APN against the development of DR.

BACKGROUND: Since sodium-glucose cotransporter 2 (SGLT2) inhibitors have a pleiotropic antiatherogenic effect, they are expected to attenuate the progression of atherosclerosis. However, whether SGLT2 inhibitors affect the tissue characteristics of the human arterial wall remains unclear. This study aimed to evaluate the effects of tofogliflozin, a selective SGLT2 inhibitor, on the tissue characteristics of the human arterial wall in type 2 diabetes (T2DM) patients without apparent cardiovascular disease (CVD). METHODS: The present study was a post hoc analysis based on data obtained from the Using Tofogliflozin for Possible Better Intervention against Atherosclerosis for Type 2 Diabetes Patients (UTOPIA) trial, which was a multicenter prospective, randomized, open-label, blinded-endpoint study conducted to evaluate the efficacy of tofogliflozin in preventing the progression of atherosclerosis in patients with T2DM. We evaluated the longitudinal change in the ultrasonic tissue characteristics of the carotid wall using gray-scale median (GSM), an established index of ultrasonic tissue characteristics. The right and left intima-medial areas were delineated, and the GSM values were evaluated (right GSM-CCA and left GSM-CCA). The average values of the right and left carotid arteries were defined as "mean GSM-CCA value." RESULTS: In a mixed-effects model for repeated measures, mean GSM-CCA, along with the right and left GSM-CCA values, did not significantly change in either the tofogliflozin (n = 168) or conventional treatment group (n = 169). In addition, the tofogliflozin and conventional treatment groups did not significantly differ regarding the change of the mean GSM-CCA (mean difference [95% CI] - 1.24[- 3.87, 1.38], P = 0.35), along with the right (mean difference [95% CI] - 2.33[- 5.70, 1.05], P = 0.18) and the left GSM-CCA (mean difference [95% CI] - 0.29 [- 3.53, 2.95], P = 0.86) values. Similar findings were obtained even after adjusting for traditional cardiovascular risk factors and/or the administration of drugs at baseline. CONCLUSIONS: The tissue characteristics of the carotid arterial wall did not change in either the tofogliflozin or conventional treatment group during the 104-week treatment period, and there was no significant difference between the treatment groups. Clinical trial registration UMIN000017607 ( https://www.umin.ac.jp/icdr/index.html ).

2p25.3 deletion syndrome is a rare genetic disorder that accompanies various phenotypic features, including early-onset obesity and intellectual disability. Here we report the first Japanese case of this deletion associated with severe obesity and diabetes mellitus. Microarray-based comparative genomic hybridization analysis identified a 3.1-Mb deletion of distal chromosome band 2p25.3, which was suspected as de novo. She also presented bilateral cataracts and adolescent-onset muscular weakness of upper limbs, both of which were uncommon in previously reported cases. Possibly, these symptoms are also important clinical features suggestive of this syndrome.

Xanthine oxidoreductase (XOR) is an enzyme that catalyzes hypoxanthine to xanthine and xanthine to uric acid, respectively. However, the underlying mechanisms of increased plasma XOR and its pathological roles in systemic diseases, such as atherosclerosis, are not fully understood. In this study, we found that changes in plasma XOR activity after bariatric surgery closely associated with those in liver enzymes, but not with those in BMI. In a mouse model of nonalcoholic fatty liver disease/steatohepatitis (NAFLD/NASH), plasma XOR activity markedly increased. Besides, purine catabolism was accelerated in the plasma per se of NASH mice and human patients with high XOR activity. In our NASH mice, we observed an increased vascular neointima formation consisting of dedifferentiated vascular smooth muscle cells (SMCs), which was significantly attenuated by topiroxostat, a selective XOR inhibitor. In vitro, human liver S9-derived XOR promoted proliferation of SMCs with phenotypic modulation and induced ROS production by catabolizing hypoxanthine released from human endothelial cells. Collectively, the results from human and mouse models suggest that increased plasma XOR activity, mainly explained by excess hepatic leakage, was involved in the pathogenesis of vascular injury, especially in NAFLD/NASH conditions.

AIMS/INTRODUCTION: Xanthine oxidoreductase (XOR) is an enzyme that catalyzes hypoxanthine and xanthine to xanthine and uric acid, respectively. Plasma XOR activity has recently been measured in humans. However, limited information is known about plasma XOR activity in patients with type 2 diabetes mellitus, and its changes after short-term glycemic control treatment. MATERIALS AND METHODS: We enrolled 28 Japanese patients (10 men/18 women) with type 2 diabetes mellitus who were hospitalized to undergo medical treatment for diabetes. Plasma XOR activity, quantified using triple quadrupole mass spectrometry and liquid chromatography, and other clinical parameters were examined at admission and 2 weeks after treatment during hospitalization. Changes in plasma XOR activity after treatment during hospitalization and associated clinical parameters were assessed. RESULTS: At the time of admission, the median plasma XOR activity was 83.1 pmol/h/mL, with a wide range of 14.4-1150 pmol/h/mL. Multiple regression analysis identified serum aspartate transaminase and alanine transaminase levels as significant and independent factors correlating with the baseline plasma XOR. Two weeks of treatment during hospitalization was associated with a significant decrease in plasma XOR activity. Changes in serum aspartate transaminase were also the only significant and independent factor correlating with changes in plasma XOR activity. CONCLUSIONS: A close relationship was observed between plasma XOR activity and liver transaminases in patients with type 2 diabetes mellitus, cross-sectionally, and also across treatment during hospitalization.

AIMS/INTRODUCTION: Crossing capillaries in the finger nailfold might potentially be a novel diabetic retinopathy (DR) biomarker that could be assessed non-invasively in the clinical setting. However, the association between crossing capillaries and DR is controversial. This study aimed to investigate the association between the percentage of crossing capillaries in the finger nailfold and DR in patients with type 2 diabetes mellitus. MATERIALS AND METHODS: This cross-sectional study enrolled 108 type 2 diabetes mellitus patients (aged 40-75 years) who visited the outpatient diabetic clinic at Osaka University Hospital, Osaka, Japan, between May and October 2019. Capillary morphology was assessed using nailfold capillaroscopy based on the simple capillaroscopic definitions of the European League Against Rheumatism Study Group. Details of DR and other laboratory data were obtained from medical records. The association between the tertile of the percentage of the crossing capillary and DR was analyzed using multivariable logistic regression. RESULTS: After adjusting for age, sex, diabetes duration, glycated hemoglobin, systolic blood pressure, body mass index, and use of renin-angiotensin system inhibitor and antihyperlipidemic medication, the percentage of crossing capillaries was significantly associated with DR (multivariable-adjusted odds ratios for increasing tertiles of the percentage of crossing capillary: 1 [reference], 2.05 [95% confidence interval 0.53-7.94], and 4.33 [95% confidence interval 1.16-16.21]; P-trend = 0.028). CONCLUSIONS: A higher percentage of crossing capillaries in the nailfold was associated with a higher risk of DR, independent of traditional risk and inhibiting factors, in patients with type 2 diabetes mellitus.

CONTEXT: T-cadherin (T-cad) is a glycosylphosphatidylinositol (GPI)-anchored cadherin that mediates adiponectin to induce exosome biogenesis and secretion, protect cardiovascular tissues, promote muscle regeneration, and stimulate therapeutic heart protection by transplanted mesenchymal stem cells. CDH13, the gene locus of T-cad, affects plasma adiponectin levels most strongly, in addition to affecting cardiovascular disease risk and glucose homeostasis. Recently, it has been suggested that T-cad exists in human serum, although the details are still unclear. OBJECTIVE: To validate the existence of T-cad forms in human serum and investigate the association with clinical parameters of type 2 diabetes patients. METHODS: Using newly developed monoclonal antibodies against T-cad, pooled human serum was analyzed, and novel T-cad enzyme-linked immunosorbent assays (ELISAs) were developed. The serum T-cad concentrations of 183 Japanese type 2 diabetes patients were measured in a cross-sectional observational study. The main outcome measure was the existence of soluble T-cad in human serum. RESULTS: There were 3 forms of soluble T-cad: a 130-kDa form with a prodomain, a 100-kDa mature form, and a 30-kDa prodomain in human serum. Using newly developed ELISAs to measure them simultaneously, we found that the 130-kDa form of T-cad positively correlated with plasma adiponectin (r = 0.28, P < .001), although a physiological interaction with adiponectin was not observed in serum. The unique 30-kDa prodomain was associated with several clinical parameters in diabetes patients. CONCLUSION: We identified 3 novel forms of soluble T-cad. Their importance as disease markers and/or biomarkers of adiponectin function and the possible bioactivity of the respective molecules require further investigation.

A 67-year-old Japanese woman who had end-stage renal disease was referred to our hospital for kidney transplantation. Abdominal CT revealed a large adrenal mass with inhomogeneity. She had a history of hospitalization for stroke and heart failure and exhibited prominent hyporeninemic hyperaldosteronism. Histological examination of the resected tumor with anti-CYP11B2 antibody indicated that she had a vascular endothelial cyst with primary aldosteronism (PA) due to multiple adrenocortical micronodules. This report implicates the pathological interaction between adrenal vascular cysts and PA-mediated vascular damage of the adrenal vein.

Adiponectin (APN) is a circulating protein specifically produced by adipocytes. Native APN specifically binds to T-cadherin, a glycosylphosphatidylinositol-anchored protein, mediating the exosome-stimulating effects of APN in endothelial, muscle, and mesenchymal stem cells. It was previously reported that APN has beneficial effects on kidney diseases, but the role of T-cadherin has not been clarified yet. Here, our immunofluorescence study indicated the existence of both T-cadherin and APN protein in pericytes, subsets of tissue-resident mesenchymal stem/progenitor cells positive for platelet-derived growth factor receptor β (PDGFRβ), surrounding peritubular capillaries. In an acute renal ischemia-reperfusion (I/R) model, T-cadherin-knockout (Tcad-KO) mice, similar to APN-KO mice, exhibited the more progressive phenotype of renal tubular damage and increased vascular permeability than wild-type mice. In addition, in response to I/R-injury, the renal PDGFRβ-positive cell area increased in wild-type mice, but opposingly decreased in both Tcad-KO and APN-KO mice, suggesting severe pericyte loss. Mouse primary pericytes also expressed T-cadherin. APN promoted exosome secretion in a T-cadherin-dependent manner. Such exosome production from pericytes may play an important role in maintaining the capillary network and APN-mediated inhibition of renal tubular injury. In summary, our study suggested that APN protected the kidney in an acute renal injury model by binding to T-cadherin.NEW & NOTEWORTHY In the kidney, T-cadherin-associated adiponectin protein existed on peritubular capillary pericytes. In an acute renal ischemia-reperfusion model, deficiency of adiponectin or T-cadherin exhibited the more progressive phenotype of renal tubular damage and increased vascular permeability, accompanied by severe pericyte loss. In vitro, adiponectin promoted exosome secretion from mouse primary pericytes in a T-cadherin-dependent manner. Adiponectin plays an important role in maintaining the capillary network and amelioration of renal tubular injury by binding to T-cadherin.

Aim: Increased crossing of finger nailfold capillaries could be a novel visual marker of early microvascular damage among type 2 diabetes mellitus patients. Although abdominal obesity is an important driver of early microvascular damage, its association with an increase in the percentage of crossing capillaries remains uncertain. We investigated the association between abdominal obesity and an increase in the percentage of crossing capillaries in the finger nailfold in patients with type 2 diabetes mellitus. Methods: This cross-sectional study enrolled 123 type 2 diabetes mellitus patients (age 40-75 years) who visited the outpatient diabetic clinic at Osaka University Hospital between May and October 2019. Abdominal obesity was defined as a waist circumference ≥ 90 cm in women and ≥ 85 cm in men. Capillary morphology was assessed by nailfold capillaroscopy based on the simple capillaroscopic definitions of the European League Against Rheumatism Study Group. The association between abdominal obesity and a high percentage of crossing capillaries in the finger nailfold (defined as the highest tertile of crossing capillaries) was analyzed using multivariable logistic regression. Results: After adjusting for age, sex, smoking status, regular exercise, duration of diabetes, glycated hemoglobin, hypertension, and dyslipidemia, abdominal obesity was significantly associated with a high percentage of crossing capillaries (multivariable-adjusted odds ratios [95% confidence interval] = 2.70 [1.05-6.90], p = 0.038). Conclusions: Abdominal obesity may play an important role in the increase in the percentage of crossing capillaries in the finger nailfold in patients with type 2 diabetes mellitus.

Neurofilament light chain (NfL) is a novel biomarker of neurodegenerative diseases. It is detectable in the peripheral blood, allowing low-invasive assessment of early signs of neurodegeneration. The level of NfL gradually increases with age; however, what other factors affect it remains unclear. The present study examined the association between blood NfL level and renal function among healthy participants undergoing a health check (n = 43, serum NfL) and patients with diabetes mellitus (n = 188, plasma NfL). All participants were 60 years of age or older; none were diagnosed with dementia. In each group, levels of blood NfL and serum creatinine significantly correlated (coefficient r = 0.50, 0.56). These associations remained statistically significant even after adjustment for age, sex, and body mass index. These findings indicate that blood NfL level might be partially affected by renal function. We recommend measuring renal function for a more precise evaluation of neuroaxonal damage, in particular, among older adults.

Mesenchymal stem/stromal cells (MSCs) are cultured adult stem cells that originally reside in virtually all tissues, and the gain of MSCs by transplantation has become the leading form of cell therapy in various diseases. However, there is limited knowledge on the alteration of its efficacy by factors in recipients. Here, we report that the cardioprotective properties of intravenously injected MSCs in a mouse model of pressure-overload heart failure largely depend on circulating adiponectin, an adipocyte-secreted factor. The injected MSCs exert their function through exosomes, extracellular vesicles of endosome origin. Adiponectin stimulated exosome biogenesis and secretion through binding to T-cadherin, a unique glycosylphosphatidylinositol-anchored cadherin, on MSCs. A pharmacological or adenovirus-mediated genetic increase in plasma adiponectin enhanced the therapeutic efficacy of MSCs. Our findings provide novel insights into the importance of adiponectin in mesenchymal-progenitor-mediated organ protections.

Gastrin regulates gastric acid secretion, and gastrin secretion itself is regulated by the negative feedback system of gastric acidity. Autoimmune gastritis (AG) is a disease where parietal cells are destroyed, resulting in decreased acid production and an elevated serum gastrin level. We herein report 2 AG cases with marked hypergastrinemia (>5,000 pg/mL). In both cases, 24-hour gastric pH monitoring showed no time when gastric pH was <2, and immunohistochemistry revealed more than 140 gastrin-positive cells per linear millimeter at the antral mucosa. This is the first report to confirm the relationship between marked hypergastrinemia and G-cell hyperplasia with AG.

A disintegrin and metalloproteinase (ADAM)12 is considered to promote cardiac dysfunction based on the finding that a small-molecule ADAM12 inhibitor, KB-R7785, ameliorated cardiac function in a transverse aortic constriction (TAC) model by inhibiting the proteolytic activation of heparin-binding-EGF signaling. However, this compound has poor selectivity for ADAM12, and the role of ADAM12 in cardiac dysfunction has not yet been investigated using genetic loss-of-function mice. We revealed that ADAM12 knockout mice showed significantly more advanced cardiac hypertrophy and higher mortality rates than wild-type mice 4 wk after TAC surgery. An ADAM12 deficiency resulted in significantly more expanded cardiac fibrosis accompanied by increased collagen-related gene expression in failing hearts. The results of a genome-wide transcriptional analysis suggested a strongly enhanced focal adhesion- and fibrosis-related signaling pathway in ADAM12 knockout hearts. The loss of ADAM12 increased the abundance of the integrinβ1 subunit and transforming growth factor (TGF)-β receptor types I and III, and this was followed by the phosphorylation of focal adhesion kinase, Akt, mammalian target of rapamycin, ERK, and Smad2/3 in the heart, which resulted in cardiac dysfunction. The present results revealed that the loss of ADAM12 enhanced focal adhesion and canonical TGF-β signaling by regulating the abundance of the integrinβ1 and TGF-β receptors.NEW & NOTEWORTHY In contrast to a long-believed cardio-damaging role of a disintegrin and metalloproteinase (ADAM)12, cardiac hypertrophy was more severe, cardiac function was lower, and mortality was higher in ADAM12 knockout mice than in wild-type mice after transverse aortic constriction surgery. The loss of ADAM12 enhanced focal adhesion- and fibrosis-related signaling pathways in the heart, which may compromise cardiac function. These results provide insights for the development of novel therapeutics that target ADAM12 to treat heart failure.

Visceral fat accumulation has a marked impact on atherosclerotic cardiovascular diseases and metabolic syndrome clustering diabetes, dyslipidemia, and hypertension. Adiponectin, an adipocyte-derived circulating protein, is a representative adipocytokine and uniquely possesses two major properties: 1) its circulating concentration is approximately 3-6 orders of magnitude greater than ordinary hormones and cytokines; 2) its concentration inversely correlates with body fat mass despite its adipocyte-specific production. Low serum levels of adiponectin correlate with cardiometabolic diseases. Extensive experimental evidence has demonstrated that adiponectin possesses multiple properties, such as anti-atherosclerotic, anti-diabetic, and anti-inflammatory activities. It has been shown to play a central role against the development of metabolic syndrome and its complications. However, even approximately 25 years after its discovery, the properties of adiponectin, including how and why it exerts multiple beneficial effects on various tissues and/or organs, remain unclear. Furthermore, the mechanisms responsible for the very high circulating concentrations of adiponectin in the bloodstream have not been elucidated. Several adiponectin-binding partners, such as AdipoR1/2, have been identified, but do not fully explain the multi-functional and beneficial properties of adiponectin. Recent advances in adiponectin research may resolve these issues. Adiponectin binds to and covers cell surfaces with T-cadherin, a unique glycosylphosphatidylinositol (GPI)-anchored cadherin. The adiponectin/T-cadherin complex enhances exosomal production and release, excreting cell-toxic products from cells, particularly in the vasculature. In this review, we discuss adiponectin and the role of the adiponectin/T-cadherin system in the maintenance of whole body homeostasis and cardiovascular protection.

We herein report a 28-year-old woman with type 1 diabetes with an asymptomatic pontine lesion and diabetic amyotrophy. She had suffered from diabetes from 10 years old. Treatment in a hospital reduced the hemoglobin A1c level from 14.2% to 7.2% for approximately 2 months. She suffered from acute-onset pain and weakness of the lower limb muscles without central nervous system manifestations. Magnetic resonance imaging showed high-intensity lesions at the brainstem and lower limb muscles on T2-weighted images. These findings and symptoms gradually resolved. Rapid treatment of poor glycemic control might increase the risk of asymptomatic pontine lesions and diabetic amyotrophy.

CONTEXT: Low serum adiponectin and high-density lipoprotein-cholesterol (HDL-C) levels are risk factors for cardiovascular disease. Patients with primary adrenal insufficiency are at higher risk of cardiovascular complications compared with healthy subjects. However, there is no information on the relationship between adiponectin and glucocorticoid replacement therapy in patients with secondary adrenal insufficiency (SAI). OBJECTIVE: To determine the effects of intrinsic adrenal function and glucocorticoid replacement therapy on serum adiponectin levels and lipid profile in patients with SAI. DESIGN: Part 1: a cross-sectional study. Part 2: a randomized, double-blind, crossover study. SETTING: Osaka University Hospital, Osaka, Japan. PATIENTS: Part 1: 58 patients diagnosed with nonfunctioning pituitary adenoma who underwent insulin tolerance test (ITT) for assessment of adrenal function. Part 2: 12 SAI patients randomly received hydrocortisone replacement therapy at a dose of 10, 20, or 30 mg/d for 4 weeks per term for three terms. OUTCOME MEASUREMENTS: Part 1: we analyzed the relationship between serum cortisol levels during ITT and serum adiponectin levels and the lipid profile. Part 2: serum adiponectin levels and lipid profile were measured every 4 weeks. RESULTS: Serum levels of adiponectin and HDL-C correlated significantly with peak cortisol levels after ITT. Serum adiponectin and HDL-C levels were significantly lower in patients with SAI than non-SAI. Serum levels of adiponectin and HDL-C increased in a hydrocortisone dose-dependent manner. CONCLUSIONS: Glucocorticoid replacement therapy increased serum levels of adiponectin, an adipose-derived anti-atherogenic factor, and HDL-C in patients with SAI.

Adiponectin is an adipocyte-derived atypically abundant circulating factor that protects various organs and tissues through its receptors, AdipoRs, calreticulin, and T-cadherin. To identify the major binding partner of circulating native adiponectin, we expressed these receptors on the surface of HEK293 cells. Adiponectin, either that in mouse or human serum, purified from serum, or produced by mammalian cells, bound to cells expressing T-cadherin, but not to those expressing AdipoR1 or calreticulin. The stable introduction of T-cadherin and AdipoR1 into CHO cells resulted in the cell surface localization of these receptors. Native adiponectin in serum bound to cells expressing T-cadherin, not to those expressing AdipoR1. The knockdown of T-cadherin, but not AdipoRs resulted in the significant attenuation of native adiponectin binding to C2C12 myotubes. Therefore, native adiponectin binding depended on the amount of T-cadherin expressed in HEK293 cells, CHO cells, and C2C12 myotubes. Collectively, our mammalian cell-based studies suggest that T-cadherin is the major binding partner of native adiponectin in serum.

Adipose tissue plays important roles in regulating whole-body energy metabolism through its storage function in white adipocytes and its dissipating function in brown and beige adipocytes. Adipose tissue also produces a variety of secreted factors called adipocytokines, including leptin and adiponectin. Furthermore, recent studies have suggested the important roles of extracellular vesicles of endosomal origin termed exosomes, which are secreted from adipocytes and other cells in adipose tissue and influence whole-body glucose and lipid metabolism. Adiponectin is known to be a pleiotropic organ-protective protein that is exclusively produced by adipocytes and decreased in obesity. Adiponectin accumulates in tissues such as heart, muscle, and vascular endothelium through binding with T-cadherin, a glycosylphosphatidylinositol-anchored (GPI-anchored) cadherin. Recently, adiponectin was found to enhance exosome biogenesis and secretion, leading to a decrease in cellular ceramides, excess of which is known to cause insulin resistance and cardiovascular disease phenotypes. These findings support the hypothesis that adipose tissue metabolism systemically regulates exosome production and whole-body metabolism through exosomes. This review focuses on intra-adipose and interorgan communication by exosomes, adiponectin-stimulated exosome production, and their dysregulation in metabolic diseases.

Two diabetic women (case 1, 75 years old; case 2, 49 years old) being treated with glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) showed no suppression of cortisol secretion on a dexamethasone suppression test (DST). However, its secretion was suppressed after switching from GLP-1 RAs to insulin. We also checked the cortisol secretion by a DST in five consecutive inpatients (case 3-7) being treated with GLP-1 RAs. The coefficients of R-R interval variation at rest and during deep breathing were lower in the two false-positive cases (case 1 and 2) than in the five true-negative cases (case 3-6). GLP-1 RAs can be switched to insulin in order to eliminate the slow absorption effect of dexamethasone by GLP-1 RAs if a DST is planned in diabetic patients receiving GLP-1 RAs.

Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) is an enzyme that specifically cleaves GPI anchors. Previous human studies suggested the relationship of GPI-PLD to insulin resistance, type 1 and type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD). However, the biological roles of GPI-PLD have not been elucidated. Here, we hypothesized that GPI-PLD impacted on lipid and glucose metabolism, especially in the liver. GPI-PLD mRNA was most highly expressed in the liver, and the hepatic mRNA level and circulating concentration of GPI-PLD were significantly augmented in diabetic mice. To investigate in vivo functions of GPI-PLD, we generated GPI-PLD knockout (GP-KO) mice. Mice lacking GPI-PLD exhibited the amelioration of glucose intolerance and hepatic steatosis under high-fat and high-sucrose diet. Furthermore, diacylglycerol (DAG) content was significantly decreased, and PKCε activity was suppressed in the livers of GP-KO mice. In vitro knockdown and overexpression experiments of GPI-PLD using rat primary hepatocytes showed the GPI-PLD-dependent regulation of intracellular DAG content. Finally, serum GPI-PLD levels were strongly and independently associated with serum alanine transaminase (R = 0.37, P = 0.0006) and triglyceride (R = 0.34, P = 0.001) levels in male subjects with metabolic syndrome. In conclusion, upregulation of hepatic GPI-PLD in diabetic conditions leads to DAG accumulation in the liver by shedding GPI anchors intracellularly, which may play a causal role in impaired hepatic insulin signaling and the progression of NAFLD.

Skeletal muscle has remarkable regenerative potential and its decline with aging is suggested to be one of the important causes of loss of muscle mass and quality of life in elderly adults. Metabolic abnormalities such as obesity were linked with decline of muscle regeneration. On the other hand, plasma levels of adiponectin are decreased in such metabolic conditions. However, plasma levels of adiponectin have been shown to inversely correlate with muscle mass and strength in elderly people especially with chronic heart failure (CHF). Here we have addressed whether adiponectin has some impact on muscle regeneration after cardiotoxin-induced muscle injury in mice. Muscle regeneration was delayed by angiotensin II infusion, mimicking aging and CHF as reported. Adiponectin overexpression in vivo decreased necrotic region and increased regenerating myofibers. Such enhanced regeneration by excess adiponectin was also observed in adiponectin null mice, but not in T-cadherin null mice. Mechanistically, adiponectin accumulated on plasma membrane of myofibers both in mice and human, and intracellularly colocalized with endosomes positive for a multivesicular bodies/exosomes marker CD63 in regenerating myofibers. Purified high-molecular multimeric adiponectin similarly accumulated intracellularly and colocalized with CD63-positive endosomes and enhanced exosome secretion in differentiating C2C12 myotubes but not in undifferentiated myoblasts. Knockdown of T-cadherin in differentiating C2C12 myotubes attenuated both adiponectin-accumulation and adiponectin-mediated exosome production. Collectively, our studies have firstly demonstrated that adiponectin stimulates muscle regeneration through T-cadherin, where intracellular accumulation and exosome-mediated process of adiponectin may have some roles.

BACKGROUND: Although obesity-related type 2 diabetes mellitus (T2DM) and sarcopenia in the elderly have been increasing worldwide, the associations among visceral fat accumulation, skeletal muscle indices (mass, strength, and quality) and cardiovascular diseases in T2DM remain poorly investigated. METHODS: We enrolled 183 Japanese T2DM inpatients (126 men, 57 women; mean age 64.7 ± 12.6 years, ± SD). The estimated-visceral fat area (eVFA) and skeletal muscle mass were measured by each device using bioelectrical impedance analysis method. We also measured grip strength by dynamometer and motor nerve conduction velocity (MCV). We analyzed the difference in skeletal muscle indices between T2DM patients with and without visceral fat accumulation, and examined the impact of skeletal muscle indices on cardiovascular diseases in patients with visceral fat accumulation. RESULTS: The prevalence of sarcopenia defined by the Consensus of Asian Working Group for Sarcopenia and low skeletal muscle mass were both lower in the visceral fat accumulation (+) group than in (-) group. However, the prevalence of weak hand grip strength was similar in the visceral fat accumulation (-) and (+) groups, indicating that considerable patients with visceral fat accumulation had weak grip strength in spite of fair skeletal muscle mass. Muscle quality [grip strength (kg)/arm muscle mass (kg)] was significantly lower in patients with visceral fat accumulation. Multiple regression analysis identified eVFA, MCV and sex as significant and independent determinants of muscle quality. In visceral fat accumulation (+) group, the patients with low muscle quality had longer duration of diabetes, lower eGFR, higher serum adiponectin, lower MCV and higher prevalence of cardiovascular diseases, compared to the patients with high muscle quality. Finally, sex- and age-adjusted models showed significant association between low muscle quality and cardiovascular diseases in all subjects (odds ratio 2.28, p = 0.012), especially in patients with visceral fat accumulation (odds ratio 2.72, p = 0.018). CONCLUSIONS: T2DM patients with visceral fat accumulation had low muscle quality, and patients with low muscle quality were more affected with cardiovascular diseases.

OBJECTIVE: The production of uric acid in murine white adipose tissue (mWAT), and that such production was augmented in obese mice, was recently reported. However, little is known about the secretion of metabolites associated with purine catabolism in human WAT (hWAT). The present study analyzed this in hWAT. METHODS: Freshly isolated hWAT and mWAT were cultured. The secretion of metabolites associated with purine catabolism was measured. Tissue distribution profiles of genes associated with purine metabolism and metabolite profiling of adipocytes in hypoxia were analyzed. RESULTS: Secretion of hypoxanthine from hWAT was higher than those of xanthine and uric acid. On the other hand, secretion of uric acid was relatively higher than xanthine and hypoxanthine in mWAT. Xanthine oxidoreductase (XOR) mRNA expression levels in hWAT were markedly lower than that in the human liver. In murine tissues, XOR mRNA expression levels in mWAT were comparable with those in the liver. Cultured human adipocytes secreted hypoxanthine, and its secretion was increased under hypoxia. The metabolic analysis of human adipocytes showed that hypoxia increased metabolites associated with de novo biosynthesis of purine nucleotides. CONCLUSIONS: The present study revealed that hypoxanthine was secreted from human adipose tissue, and the secretion might be increased in local hypoxia.

Adiponectin, an adipocyte-derived circulating protein, accumulates in vasculature, heart, and skeletal muscles through interaction with a unique glycosylphosphatidylinositol-anchored cadherin, T-cadherin. Recent studies have demonstrated that such accumulation is essential for adiponectin-mediated cardiovascular protection. Here, we demonstrate that the adiponectin/T-cadherin system enhances exosome biogenesis and secretion, leading to the decrease of cellular ceramides. Adiponectin accumulated inside multivesicular bodies, the site of exosome generation, in cultured cells and in vivo aorta, and also in exosomes in conditioned media and in blood, together with T-cadherin. The systemic level of exosomes in blood was significantly affected by adiponectin or T-cadherin in vivo. Adiponectin increased exosome biogenesis from the cells, dependently on T-cadherin, but not on AdipoR1 or AdipoR2. Such enhancement of exosome release accompanied the reduction of cellular ceramides through ceramide efflux in exosomes. Consistently, the ceramide reduction by adiponectin was found in aortas of WT mice treated with angiotensin II, but not in T-cadherin-knockout mice. Our findings provide insights into adiponectin/T-cadherin-mediated organ protection through exosome biogenesis and secretion.

AIMS/INTRODUCTION: It is suggested that a positive psychosocial condition has a good effect on health and glycemic control. However, there has been no research to evaluate the association between positive psychosocial factors and diabetic nephropathy (DN). The aim of the present study was to evaluate the association between psychosocial factors and DN in patients with type 2 diabetes. MATERIAL AND METHODS: To assess psychosocial condition, six indicators (happiness score, Life Orientation Test-revised score as an indicator of dispositional optimism, laughter frequency, self-awareness of stress, social network and social support) were assessed by a self-administered questionnaire, and associations between these psychosocial indicators and the presence of DN were examined. RESULTS: A cross-sectional analysis of patients with (n = 123) and without DN (n = 220) showed that a high score for happiness (odds ratio [OR] per 1 standard deviation 0.71, 95% confidence interval [CI] 0.57-0.89, P = 0.003), high Life Orientation Test-revised score (OR per 1 standard deviation 0.77, 95% CI: 0.61-0.98, P = 0.035), less self-awareness of stress (OR 0.56, 95% CI: 0.34-0.90, P = 0.017), high connection of social network (OR 0.55, 95% CI: 0.35-0.87, P = 0.010) and high social support (OR 0.61, 95% CI: 0.38-0.96, P = 0.035) were associated with a reduced risk of prevalence of DN. Similar results were observed even after adjustment for the following conventional risk factors of DN: age, sex, duration of diabetes, hemoglobin A1c, hypertension, dyslipidemia and current smoking. CONCLUSIONS: The present study showed that five out of six prespecified indicators of psychosocial condition were significantly associated with the presence of DN in Japanese patients with type 2 diabetes.

Sleep pattern has been shown to be associated with type 2 diabetes mellitus. Here, we investigated the difference in bedtime, waking time and estimated sleep duration in type 2 diabetes mellitus patients with or without visceral fat accumulation, using a questionnaire on sleep patterns. The study participants were 59 Japanese type 2 diabetes mellitus patients (men/women 34/25, age 64.5 ± 12.1 years). Visceral fat accumulation was defined as estimated visceral fat area ≥100 cm2 . The patients with visceral fat accumulation (n = 40) showed significantly later bedtime (23.51 ± 01.27 h in the [+] group vs 22.49 ± 01.23 h in the [-] group) and shorter estimated sleep duration (6.6 ± 1.4 h in the [+] group vs 7.9 ± 1.0 h in the [-] group) on weekdays, compared with those without (n = 19). Later bedtime and shorter estimated sleep duration existed in the type 2 diabetes mellitus patients with visceral fat accumulation, compared with those without.

Tissue inhibitors of metalloproteinases (TIMPs) regulate matrix metalloproteinase activity and maintain extracellular matrix homeostasis. Although TIMP-3 has multiple functions (e.g., apoptosis, inhibition of VEGF binding to VEGF receptor, and inhibition of TNFα converting enzyme), its roles in thermogenesis and metabolism, which influence energy expenditure and can lead to the development of metabolic disorders when dysregulated, are poorly understood. This study aimed to determine whether TIMP-3 is implicated in metabolism by analyzing TIMP-3 knockout (KO) mice. TIMP-3 KO mice had higher body temperature, oxygen consumption, and carbon dioxide production than wild-type (WT) mice, although there were no differences in food intake and locomotor activity. These results suggest that metabolism is enhanced in TIMP-3 KO mice. Real-time PCR analysis showed that the expression of PPAR-δ, UCP-2, NRF-1 and NRF-2 in soleus muscle, and PGC-1α and UCP-2 in gastrocnemius muscle, was higher in TIMP-3 KO mice than in WT mice, suggesting that TIMP-3 deficiency may increase mitochondrial activity. When exposed to cold for 8 hours to induce thermogenesis, TIMP-3 KO mice had a higher body temperature than WT mice. In the treadmill test, oxygen consumption and carbon dioxide production were higher in TIMP-3 KO mice both before and after starting exercise, and the difference was more pronounced after starting exercise. Our findings suggest that TIMP-3 KO mice exhibit enhanced metabolism, as reflected by a higher body temperature than WT mice, possibly due to increased mitochondrial activity. Given that TIMP-3 deficiency increases energy expenditure, TIMP-3 may present a novel therapeutic target for preventing metabolic disorders.

BACKGROUND: A drug delivery system that constitutively and effectively retains cardioprotective reagents in the targeted myocardium has long been sought to treat acute myocardial infarction. We hypothesized that a scaffold-free induced adipocyte cell-sheet (iACS), transplanted on the surface of the heart, might intramyocardially secrete multiple cardioprotective factors including adiponectin (APN), consequently attenuating functional deterioration after acute myocardial infarction. METHODS AND RESULTS: Induced ACS were generated from adipose tissue-derived cells of wild-type (WT) mice (C57BL/6J), which secreted abundant APN, hepatocyte growth factor, and vascular endothelial growth factor in vitro. Transplanted iACS secreted APN into the myocardium of APN-knockout (KO) mice at 4 weeks. APN was also detected in the plasma of iACS-transplanted APN-KO mice at 3 months (245 ± 113 pg/mL). After left anterior descending artery ligation, iACS, generated from either WT (n=40) or APN-KO (n=40) mice, were grafted onto the surface of the anterior left ventricular wall of WT mice, or only left anterior descending artery ligation was performed (n=43). Two days later, inflammation and infarct size were significantly diminished only in the WT-iACS treated mice. One month later, cardiomyocyte diameter and percent fibrosis were smaller, whereas ejection fraction and survival were greater in the WT-iACS treated mice compared with the KO-iACS-treated or nontreated mice. CONCLUSIONS: Cardioprotective factors including APN, hepatocyte growth factor, and vascular endothelial growth factor were secreted from iACS. Transplantation of iACS onto the acute myocardial infarction heart attenuated infarct size, inflammation, and left ventricular remodeling, mediated by intramyocardially secreted APN in a constitutive manner. This method might be a novel drug delivery system to treat heart disease.

Extracellular matrix (ECM) degradation is performed primarily by matrix metalloproteinases (MMPs). MMPs have recently been shown to regulate synaptic activity in the hippocampus and to affect memory and learning. The tissue inhibitor of metalloproteinase (Timp) is an endogenous factor that controls MMP activity by binding to the catalytic site of MMPs. At present, four Timp isotypes have been reported (Timp-1 through Timp-4) with 35-50% amino-acid sequence homology. Timp-3 is a unique member of Timp proteins in that it is bound to the ECM. In this study, we used the passive avoidance test, active avoidance test, and water maze test to examine the cognitive function in Timp-3 knockout (KO) mice. Habituation was evaluated using the open-field test. The water maze test showed that Timp-3 KO mice exhibit deterioration in cognitive function compared with wild-type (WT) mice. The open-field test showed decreased habituation of Timp-3 KO mice. Immunostaining of brain slices revealed the expression of Timp-3 in the hippocampus. In situ zymography of the hippocampus showed increased gelatinolytic activity in Timp-3 KO mice compared with WT mice. These results present the first evidence of Timp-3 involvement in cognitive function and hippocampal MMP activity in mice. Moreover, our findings suggest a novel therapeutic target to be explored for improvement of cognitive function in humans.

OBJECTIVES: This study examined the association of mutations in adiponectin gene with the prevalence of coronary artery disease (CAD). BACKGROUND: Coronary artery disease is a major cause of mortality in the industrial countries. Adiponectin gene locus, chromosome 3q27, is the candidate site for CAD. We have reported that adiponectin has antiatherogenic and antidiabetic properties, and that the plasma levels negatively correlated with body mass index (BMI) are significantly low in patients with CAD or type 2 diabetes. METHODS: The study subjects were 383 consecutive patients with angiographically confirmed CAD and 368 non-CAD subjects adjusted for age and BMI in the Japanese population. Single nucleotide polymorphisms (SNPs) in the adiponectin gene were determined by Taqman polymerase chain reaction (PCR) method or a PCR-based assay for the analysis of restriction fragment length polymorphism. The plasma adiponectin concentration was measured by enzyme-linked immunosorbent assay. RESULTS: Among SNPs, the frequency of I164T mutation was significantly higher in CAD subjects (2.9%) than in the control (0.8%, p < 0.05). The plasma adiponectin levels in subjects carrying the I164T mutation were significantly lower than in those without the mutation, and were independent of BMI. In contrast, SNP94 and SNP276, which are reported to be associated with an increased risk of type 2 diabetes, were associated neither with CAD prevalence nor with plasma adiponectin level. Subjects with I164T mutation exhibited a clinical phenotype of the metabolic syndrome. CONCLUSIONS: The I164T mutation in the adiponectin gene was a common genetic background associated with the metabolic syndrome and CAD in the Japanese population.

間葉系幹細胞（MSCs）を用いた急性発症1型糖尿病の治療法を開発した。近年、抗がん剤として免疫チェックポイント阻害薬（ICI）が注目され、種々の悪性腫瘍に対して使用が拡大している。ICIの副作用として種々の自己免疫疾患が挙げられるが、中でも急性発症1型糖尿病は、膵β細胞を完全に失うことで血糖コントロールは極めて不良となり、合併症の進行、患者のQOL、予後が著しく損なわれる。癌は2040年には年間2890万人が新たに罹患し、その36.1%はICIが適応されると予想されており、ICI投薬患者の約0.5%に1型糖尿病の発症を認めることより、年間約5.2万人に糖尿病が新規発症すると予測されるが、未だ有効な治療法は確立していない。 通常は糖尿病を発症しない雄性NOD/ShiJclマウスに、抗マウスPD-L1モノクローナル中和抗体を投与することで、ICIに誘発される急性発症1型糖尿病が発症するモデルを構築した。本モデルにヒト脂肪由来MSC(hMSC) を投与して糖尿病の発症率および血糖推移を検討し、その有効性を確認し、MSCsの産生するエクソソームがその作用を担う可能性を示した（Diabetologia in Press、特願2021-26666）。 また、アディポネクチン結合パートナーであるT-cadherinは血中にエクソソームの構成成分としてのみならず、大部分は遊離タンパクとして存在し、糖尿病患者群の中でHBA1cなどのパラメータと有意な相関を示すことを明らかにし（Fukuda et al., JCEM2021）、ストレプトゾシン惹起糖尿病モデル等のインスリン枯渇状態で増加し、膵β細胞の増殖を促進する新しい液性因子であることを明らかにした（Okita et al. 投稿中）。

Adiponectin is a good protein secreted from fat and is a factor that protects us from various lifestyle-related diseases. Until now, it has been thought that a receptor called AdipoR plays a role, but in fact, we demonstrated that it functions by binding to a special membrane protein called T-cadherin, entering cells, and producing particles called exosomes. This function is also important for stem cell therapies and may be applied to the treatment of severe heart failure and immune checkpoint inhibitor-associated type 1 diabetes. We also found that T-cadherin is released from cells and is also present in the blood, increasing in a diabetic state and helping the growth of insulin-producing cells in the pancreas.

We generated and analyzed a renal ischemia and reperfusion model in mice lacking adiponectin or T-cadherin. Our study clearly showed that adiponectin/T-cadherin system played a significant role in maintenance for vascular barrier function and homeostasis of vascular pericytes. Furthermore, we established ELISA system to measure soluble T-cadherin in bloodstream and demonstrated the existence of three forms of soluble T-cadherin (130-kDa, 100-kDa, and 30-kDa). Soluble T-cadherin concentrations were significantly correlated with various clinical parameters, suggesting that soluble T-cadherin is a novel biomarker.

Xanthine oxidoreductase (XOR) is an enzyme that catalyzes hypoxanthine to xanthine and uric acid. Plasma XOR activity has recently been measured in human subjects. In this study, a close relationship was observed between plasma XOR activity and liver transaminases in patients with type 2 diabetes, cross-sectionally, and also across hospitalized treatment. Furthermore, we found that changes in plasma XOR activity after bariatric surgery closely associated with those in liver enzymes, but not with those in body mass index (BMI). In a mouse model of nonalcoholic fatty liver disease/steatohepatitis (NAFLD/NASH), plasma XOR activity markedly increased. In NASH mice, we observed increased vascular neointimal formation consisted of dedifferentiated vascular smooth muscle cells, which was significantly attenuated by a selective XOR inhibitor. Collectively, these results suggest that increased plasma XOR activity in NAFLD/NASH is involved in the pathogenesis of vascular injury.

We identified T-cadherin, a cell-surface membrane protein, as the specific receptor for native adiponectin. Adiponectin enhances exosome biogenesis and secretion from the cells expressing T-cadherin, and protects the endothelium, renal function, stimulates muscle regeneration. Cell therapy based on mesenchymal stem cells needs circulating adiponectin to secrete exosomes and exert therapeutic functions to heart failure models. T-cadherin circulates also as soluble forms and we developed a new EIA system. We also uncovered the importance of the Favine-regulated pathway in atherosclerosis.

A series of our studies find out the following novel mechanism. Adiponectin, an adipocyte-specific secretory circulating protein, suppresses the development of atherosclerosis through T-cadherin, a GPI-anchored cell surface protein. Adiponectin binds to specific domain of T-cadherin with high affinity. We also discover the novel mechanism explaining the variety of organ protective role of adiponectin. Adiponectin significantly enhances the exosome production via T-cadherin. We furthermore demonstrate that GPI-PLD, a GPI-anchor cleavage enzyme, is significantly increased especially in liver, and GPI-PLD knockout mice escape from diet-induced diabetes, suggesting that GPI-PLD inhibitors will be useful for novel therapeutic tools against diabetes.

Adiponectin is known to be a beneficial secreting protein. We revealed that adiponectin accumulates in heart, vessel, and muscle through a unique high-affinity interaction with a cell-surface protein called T-cadherin. Furthermore, adiponectin stimulates exosome biogenesis and secretion, thereby contributes organ protections and regenerations. Exosome is known to be a machinery to dispose unnecessary materials to keep cellular homeostasis and a packet-signaling machinery to enhance intercellular communications. The long mystery of functional mechanism of this beneficial protein can now be clearly explained by our findings, stimulation of exosome biogenesis. We are going to apply such fundamental mechanism of adiponectin function to novel medications.

Adiponectin accumulated onto the damaged vascular area such as atherosclerotic lesion and exhibited anti-atherosclerotic effect through T-cadherin. Adiponectin has been shown to bind a specific region of T-cadherin with a high affinity. Moreover, present study discovered a novel insight that adiponectin enhances exosome production via T-cadherin, suggesting the adiponectin/T-cadherin system plays a beneficial and protective role against cellular damages. We herein showed that GPI-PLD was a significant enzyme increasing hepatic DAG, finally causing insulin resistance, and hepatic GPI-PLD was increased in a diabetic condition. Our results suggest that GPI-PLD is a novel therapeutic target for diabetes.We showed that Favine promoted adipocyte differentiation and lipid accumulation in adipocytes. We further described the possibility that Favine modulated inflammation in vessels.

Little is known about the secretion of metabolites associated with purine catabolism in human white adipose tissue (hWAT). Human adipose tissue secreted hypoxanthine, a precursor of uric acid in purine catabolism, more than xanthine and uric acid. Hypoxanthine secretion and intracellular metabolites associated with purine biosynthesis were augmented under hypoxia in human adipocytes (Obesity, in press). The static metabolic analyses showed that glutamate and constitutive metabolites of tricarboxylic acid (TCA) cycle were increased in WAT of obese mice. Moreover, in vivo metabolic turnover analyses demonstrated that glucose-derived these metabolites were dynamically and specifically produced in obese WAT. In adipocytes, glutamate treatment reduced adiponectin secretion and insulin-mediated glucose uptake and phosphorylation of Akt. These data suggest that high intra-adipocytes glutamate level potentially relates to adipocyte dysfunction in obesity (J.Biol.Chem. 2017).

メタボリックシンドロームにおけるサルコペニアに関する研究は、大阪大学医学部附属病院内分泌代謝内科及び川崎病院糖尿病内分泌内科に入院した症例を対象に評価を行っている。主に筋肉量や筋力を測定するとともに代謝パラメーターや骨密度、血中アディポネクチン値などとの相関関係を解析している。現在約130名エントリーしており、今後も症例数を増やしながら解析を行っていく。 末梢血遺伝子発現プロファイルの解析の１つとして、住友病院内分泌代謝内科入院症例（代謝異常非合併肥満者、耐糖能障害症例）を対象に解析を行った。本検討は、全例腹部CTによる内臓脂肪及び皮下脂肪面積を定量評価できている点において極めて精度の高いものである。結果、内臓脂肪は1,354個の遺伝子プローブの発現に影響を与えるのに対し、皮下脂肪や体格指数（BMI）は全く末梢血遺伝子発現に影響を与えなかった。また、年齢あるいは性別は、それぞれ625個、52個の遺伝子プローブ発現に影響することを示した。特に内臓脂肪蓄積に伴い、KLF10の発現が顕著に減少しており、メタボリックシンドローム発症病態における新たな分子を見出した。 さらに、Gene ontology解析の結果、炎症、酸化ストレス、免疫応答、脂質代謝や糖代謝に関連する遺伝子群への影響は、内臓脂肪は約20-30%の遺伝子に影響するのに対して、皮下脂肪は3-5%しか影響を与えないことも明らかにした。以上、論文報告を行った。

内臓脂肪蓄積は糖代謝・脂質代謝・血圧の異常に加え、アディポネクチン分泌不全を始めとするアディポサイトカイン異常や易炎症性、易血栓性を伴い動脈硬化性疾患にいたる。本研究は１）内臓脂肪蓄積特異的な流血中の炎症細胞発現遺伝子を同定し、２）生体イメージング技術により炎症細胞を可視化し脂肪蓄積過程で脂肪細胞と炎症細胞の相互作用をダイナミックに捉え、３）内臓脂肪と皮下脂肪組織の代謝物の比較分析も合わせ行って、内臓脂肪の生物学をおしすすめ、急増する過栄養病態への対策に貢献しようとするものである。本年度は、１）血球発現遺伝子解析については、肥満・糖尿病教育入院をおこない、内臓脂肪、皮下脂肪量の評価もおこなった対象をエントリーし、順次全血球細胞からのRNAを抽出してマイクロアレイ解析の準備をすすめた。マウスにおける実験医学研究としては、アディポネクチン欠損（Adipo-/-）マウスと野生型（WT）マウスの血球細胞を分析し、両者に差がある可能性を認めたため詳細な検討をすすめている。２）生体イメージング法を用いた脂肪組織における免疫細胞動態については、LysMEGFP、CD11cEYFPTgマウスに高脂肪高蔗糖（HF/HS）食を負荷して、LysMEGFP陽性細胞が負荷早期から活発に活動することを観察した。脂肪細胞から分泌されるS100A8が重要な役割を果たす可能性が示された。LysMEGFP陽性細胞の大部分は末血では好中球であるのに対し脂肪組織ではマクロファージが多くを占めた。またこれら炎症細胞の動態におよぼすアディポネクチンの意義を明らかにするためにLysMEGFP-Adipo-/-およびCD11cEYFP-Adipo-/-マウスの作製を進めた。３）内臓脂肪組織、皮下脂肪組織の代謝物解析については、肥満モデルマウスから腸間膜・皮下脂肪を採取し基礎検討を行った。

Adiponectin, an adipose-specific secretory protein, abundantly exists in bloodstream. Here, we showed that adiponectin accumulates onto specific tissues or cells and thus exhibits organ protective effects. Adiponectin binds to T-cadherin and accumulates onto aorta, heart, and skeletal muscle in which T-cadherin is highly expressed. Present study focused on the accumulation of adiponectin in aorta, because adiponectin has been shown to possess anti-atherosclerotic property. Adiponectin resides on aortic endothelial cells under steady condition. Interestingly, in atherosclerotic plaque lesion, adiponectin exists not only in endothelial cells but also on the surface of smooth muscle cells with synthetic phenotype and monocytes attaching to endothelial cells. Data shown here indicates that adiponectin/T-cadherin system plays a crucial role in maintaining homeostasis in vivo.

Adiponectin (Adp) protein was detected in murine aorta, heart, and skeletal muscle. In the atherosclerotic lesion, Adp was detected in endothelial cells, synthetic smooth muscle cells and monocytes attaching to endothelial cells. Tissue accumulation of Adp was reduced in T-cadherin knockout mice while plasma Adp level significantly increased compared to control. Accumulation and function of Adp exerted through T-cadherin. ELISA system to measure C1q- Adp complex was established, and circulating levels of complex were associated with body mass index, visceral and subcutaneous fat area, and atherosclerosis. Adp possessed an anti-fibrotic effect of heart partly through the suppression of beta-catenin pathway. We generated Favine (Fav) knockout mice. Adipose tissue and body weight were significantly less in Fav-KO mice than control. It was revealed that Fav has both adipogenic and lipogenic effects on adipocytes.

Adipocytes overexpressed S100A8 in early phase of obesity. Anti-S100A8 antibody suppressed dynamic movement of macrophage in adipose tissue of obesity. Exogenous adiponectin accumulated mainly to stromal vascular fraction (SVF) of adipose tissue and aorta without ectopic expression. Adipose SVF adiponecitn increased in obesity. Adiponectin covered surface of endothelial cells in aorta, and was additionally detected on smooth muscle cells in atherosclerotic lesion. Binding of adiponectin to aorta required T-cadherin. Also, concentration of adiponectin binding to C1q was elevated in spite of hypoadiponectinemia in patients with acute coronary syndrome. These data suggest adiponectin belongs to a new category of endocrine factors. Type 2 diabetics with metabolic syndrome often had polyvascular lesions by ultrasonography and abnormalities of adipocytokines. Estimation of arteriosclerosis and visceral fat are potentially useful for the management of these patients.

Cystatin C was identified as an adiponectin binding protein. In macrophage, adiponectin regulated vascular endothelial growth factor-C. In vascular endothelial cell culture, cystatin C abrogated the anti-inflammatory effects of adiponectin. The clearance rate of adiponectin was decreased by cystatin C in mouse model. Although adiponectin has anti-atherogenic properties, hyper-adiponectinemia in renal failure is associated with increased risk of atherosclerosis. The present findings suggest that the high cystatin C level of renal failure impaired vascular metabolism through the direct binding with adiponectin.

Adenovirus-mediated supplement of adiponectin to adiponectin-deficient mice demonstrated that adiponectin was accumulated in the heart tissue and exhibited cardio-protective role. S100A8 was identified as a novel adipocytokine from mice white adipose tissue by cDNA microarray analysis. Glucocorticoid was one of regulators for adiponectin expression and its regulatory mechanism was clarified in present study.

アクアポリン・アディポース(aquaporin adipose;AQPap)ノックアウトマウスの解析 前年度に引き続き、AQPap ノックアウトマウス(AQPap KO)の解析を継続した。体重変化を24週齢まで観察すると、AQPap KOは12週齢以降になると有意に肥満を呈することを見出した。このとき、野生型マウス(WT)に比し耐糖能障害および全身性のインスリン抵抗性、アディポサイトカインの分泌異常を伴っていた。白色脂肪組織の形態学的検討により、AQPap KOは肥大化した脂肪細胞の増殖が観察された。さらに、体重差のない若週齢から高脂肪・高蔗糖食負荷を行うと速やかにAQPap KOは重篤なインスリン抵抗性を伴う肥満を呈した。次に、AQPap KOが肥満を来す原因につき、体重差のない若週齢のマウスを用いて検討を加えた。まず、酸素消費量および呼吸商を測定したが両マウス間で差はなく、脂肪組織、肝臓、骨格筋における肥満・糖尿病関連遺伝子を調べたが明らかな差は見い出せなかった。次に、グリセロール代謝の律速酵素であるグリセロールキナーゼの活性を調べたところ、白色脂肪組織のグリセロールキナーゼ活性がAQPap KOで有意に上昇していた。そこで、3T3-L1脂肪細胞にRNAiを用いてAQPapをknockdownすると、細胞内グリセロール含量が増加し、グリセロールキナーゼ潜性が上昇し、オレイン酸取り込みも増加し、中性脂肪含量が増加した。すなわち、AQPapは脂肪細胞のグリセロールチャネルとして機能し、本分子の欠損により細胞外へのグリセロール放出が障害され、グリセロールキナーゼ活性が誘導され、最終的に脂肪細胞が肥大し肥満を呈することを明らかにした。