Prevention of diabetes by a hydrolysed casein-based diet in diabetes-prone BioBreeding rats does not involve restoration of the defective natural regulatory T cell function

Abstract

To the Editor: Diabetes-prone (DP)-BioBreeding (BB) rats show reduced natural regulatory T cell (nTreg; CD4+/CD25+/forkhead box P3 [FOXP3]+) levels and function, and spontaneously develop type 1 diabetes from 70 days of age [1, 2]. Adoptive transfers of nTregs from diabetes-resistant (DR)-BB rats to DP-BB rats prevents diabetes in DP-BB rats [3, 4]. Environmental factors such as diet are critical triggers for the development of type 1 diabetes [5]. Using the DP-BB rat model for type 1 diabetes, we and others have shown that a hydrolysed casein (HC)-based diet reduces the incidence of diabetes from 90% to 50%, and delays the mean time of diabetes onset [5–8]. Reduced dietary diabetogenic triggers, skewing of immune responses and induction of islet neogenesis are thought to be the main mechanisms behind the effects of the HC-based diet [5–8].