Persons with latent autoimmune diabetes in adults express higher dipeptidyl peptidase-4 activity compared to persons with type 2 and type 1 diabetes.

AIMS: We aimed to determine serum dipeptidyl peptidase-4 (DPP-4) activity in a group of persons with latent autoimmune diabetes in adults (LADA) and to compare it with persons with type 1, type 2 diabetes and healthy controls. METHODS: DPP-4 activity measurement was performed in 67 persons (21 with type 1, 26 type 2 and 19 with LADA) and 13 healthy age and gender matched controls. RESULTS: Persons with LADA showed highest DPP-4 activity among the study groups (32.71±3.55 vs 25.37±2.84 vs 18.57±2.54 vs 18.57±2.61U/L p<0.001). Mean glutamic acid autoantibody in persons with LADA was 164.32±86.28IU/mL. It correlated with DPP-4 activity (r=0.484, p=0.013). Furthermore, DPP-4 activity correlated with waist circumference (r=0.279, p=0.034) and glycated haemoglobin A1c (r=0.483, p<0.001), as well as with LDL cholesterol (r=0.854, p<0.001) and total daily insulin dose (r=0.397, p=0.001). In the multinomial regression analysis DPP-4 activity remained associated with both LADA (prevalence ratio 1.058 (1.012-1.287), p=0.001) and type 1 diabetes (prevalence ratio 1.506 (1.335-1.765), p<0.001) while it did not show an association with type 2 diabetes (prevalence ratio 0.942 (0.713-1.988), p=0.564). CONCLUSIONS: Persons with LADA express higher DPP-4 activity compared to persons with both type 1 and type 2 diabetes. The possible pathophysiological role of DPP-4 in the LADA pathogenesis needs to be further evaluated.

Neurotrophic role of interleukin-6 and soluble interleukin-6 receptors in N1E-115 neuroblastoma cells.

Interleukin 6 (IL-6) plays a role in physiological and pathophysiological processes in neuronal cells. We studied whether IL-6 plays a role in neuroblastoma cells in culture. These studies demonstrate that N1E-115 cells constitutively express IL-6 but not IL-6R. Exogenous IL-6 stimulated neuronal proliferation in a dose-dependent manner. Under serum-free conditions soluble IL-6 receptors (sIL-6R) alone or in combination with IL-6 exerted significant proliferative effects, while IL-6 alone failed to promote cell proliferation. Neutralizing anti-IL-6 antibody caused a 30-40% reduction in IL-6 mediated proliferation. Our results suggest the importance of IL-6/sIL-6R for proliferation and survival of N1E-115 adrenergic neuroblastoma cells.

Total plasma antioxidants in first-degree relatives of patients with insulin-dependent diabetes.

Insulin-dependent diabetes mellitus (IDDM) is a chronic disorder that results from autoimmune destruction of the pancreatic beta-cells. Recent evidence suggests that oxidative damage, resulting from both cytokine-induced production of toxic free radicals and low antioxidant capacity of the beta-cell plays a significant role in the pathogenesis of IDDM. Islet cell antibodies (ICA) have been the best validated marker of risk for the development of IDDM in predisposed individuals, i.e. first-degree relatives of patients with IDDM. We investigated the total plasma antioxidant status (TAS) in both ICA-positive and ICA-negative first-degree relatives of patients with IDDM, to assess the level of overall protection against oxidative damage. TAS was significantly lowered in ICA-positive when compared to both ICA-negative and healthy subjects (p < 0.001), while no significant difference was found in comparison to recently diagnosed patients with IDDM. TAS values were not significantly influenced by gender, age and smoking habits in all groups, as well as by ICA titers in the group of ICA-positive subjects. Results indicate that prediabetic condition, apart from well-established immunological and metabolic alterations, could be associated with biochemical changes revealing complex disturbances of the antioxidative defence system. Although TAS is a functional rather than specific marker, its measurement is likely to be a valuable tool for understanding the mechanisms of specific beta-cell injury.