Effects of BCG Vaccination on the Morphometry of Pancreatic Islets of Langerhans of Streptozotocin-Treated Diabetic Rats

Abstract

Immune-mediated (type 1) diabetes mellitus (IMD) is an autoimmune disease resulting from chronic destruction of pancreatic 4-cells by autoreactive T lymphocytes. Although there has been much advancement in diabetes management, targeting the precise etiology of the disease process has remained elusive. Recent progress in the understanding of the immunopathogenesis of IMD, however, has led to new intervention strategies, especially antigen-based therapies given as altered peptide ligands (APL) or as vaccines. There have been many attempts at immunologic modulation as a block or prevention of the underlying process. Recent evidence from animal studies has raised the possibility that immunization by vaccines can influence the pathogenesis of type 1 diabetes mellitus. In non-obese diabetic (NOD) mice and biobreeding (BB) rats, complete Freund's adjuvant (CFA) and Bacille Calmette-Guérin (BCG) vaccines have successfully been used to interrupt or prevent the onset and recurrence of type Idiabetes. In this study, we investigated the effect of BCG vaccination on multiple low dose streptozotocin-induced diabetes (MLDS) in mice, with particular emphasis on the immunohitochemistry and morphometry. The mice were pretreated with BCD vaccine, 7 days before starting multiple low dose stretpozotocin (STZ). We observed the effects of BCG vaccination on the body weight, blood glucose concentration, serum insulin, pancreatic insulin contents and quantitative analysis of islet morphology/viability of the STZ-induced insulitis after the animals were sacrificed. The findings of the present study showed that BCG-treated mice improved in body weights, serum insulin, pancreatic insulin contents and reduced blood glucose concentration. There was also a reduction in the level of 4-cell apoptosis, and a significant (p <0.05) increase in 4-cell regeneration, and 4-cell mass. Our results suggest that BCG vaccination exerts some positive effects in the diabetic state by improving cellular integrity of islet cells, and drastically reducing the development of insulitis and overt diabetes in MLDS diabetic mice.