Serum adipocyte fatty acid-binding protein levels are associated with peripheral arterial disease in women, but not men, with type 2 diabetes mellitus.

BACKGROUND: Adipocyte fatty acid-binding protein (A-FABP) has been recognized as an important player in macrophage cholesterol trafficking and inflammation, and may promote the development of atherosclerosis. To further elucidate the role of A-FABP in atherosclerosis in diabetes, we investigated the relationship between serum A-FABP concentrations and peripheral arterial disease (PAD) in patients with type 2 diabetes mellitus (T2DM). METHODS: In all, 488 inpatients with T2DM were enrolled in the study (254 men, 234 women; mean (±SD) age 57.3 ± 13.0 years). The severity of peripheral arterial stenosis was assessed by ultrasound examination. Serum A-FABP concentrations were determined by ELISA. RESULTS: Serum A-FABP concentrations were significantly higher in patients with than without PAD (8.0 ± 3.3 vs 6.2 ± 1.6 ng/mL, respectively; P < 0.05). Interestingly, there was an obvious gender-related difference in PAD patients with T2DM, with the stenosis rate being higher for female than male T2DM patients in the third A-FABP tertile. Logistic regression analysis revealed that serum A-FABP concentrations were an independent risk factor for PAD in female T2DM patients (odds ratio 1.890, 95% confidence interval 1.041-3.432; P = 0.036), but not in male T2DM patients. Correlation analyses revealed that A-FABP concentrations were correlated with body mass index (BMI), diastolic blood pressure, urinary microalbumin, and serum creatinine in male patients, and with BMI, duration of T2DM, fasting blood glucose, and serum creatinine in female patients. CONCLUSIONS: Serum A-FABP concentrations are closely associated with PAD in Chinese women with T2DM. The study findings suggest that A-FABP may be a more specific marker of PAD in diabetic women than men.

Saxagliptin Induces ß-Cell Proliferation through Increasing Stromal Cell-Derived Factor-1α In Vivo and In Vitro.

Dipeptidyl peptidase-4 inhibitors, such as saxagliptin, have been reported to have beneficial effects on ß-cell function, but the specific underlying mechanism remains unclear. Stromal cell-derived factor-1α (SDF-1α), a chemokine produced in multiple organs, has been considered as a crucial regulator in promoting ß-cell survival. Here, we speculate that SDF-1α might mediate the effect of saxagliptin on improving ß-cell function. After 12-week saxagliptin treatment in high-fat diet/streptozotocin-induced diabetic rats, significant improvement in pancreas insulin secretion capacity evaluated by hyperglycemia clamp and increased ß-cell to α-cell areas ratio were observed. Saxagliptin significantly induced ß-cell proliferation and upregulated the expression of proliferation-related factors including c-myc and cyclind D1 determined with western blotting from the isolated islets. The expression/activity of DPP-4 was significantly reduced and paralleled with the restoration of SDF-1α levels in the saxagliptin-treated diabetic rats, subsequently the key WNT-signaling regulators, ß-catenin, and AKT were activated. However, the effect of saxagliptin inducing ß-cell proliferation was attenuated when we silenced the SDF-1α receptor (CXCR4) with RNAi in INS cell lines. Collectively, our data indicate that SDF-1α mediates the protective effect of saxagliptin on ß-cell proliferation, suggesting that DPP-4 inhibitors have the potential role on delaying ß-cell failure and SDF-1α could be a therapeutic target of ß-cell regeneration.