Inhibition of Insulin Degrading Enzyme and Insulin Degradation by UV-Killed Lactobacillus acidophilus

Probiotics have beneficial effects on management of type 2 diabetes (T2D). The major hallmarks of T2D are insulin deficiency and insulin resistance which emphasize insulin therapy in onset of disease. Lactobacilli such as Lactobacillus acidophilus (L. acidophilus) have well known properties on prevention of T2D and insulin resistance but not on insulin degradation. Insulin-degrading enzyme (IDE) degrades insulin in the human body. We studied the effects of cell-free supernatant (CFS) and ultraviolet (UV)-killed L. acidophilus (ATCC 314) on IDE activity and insulin degradation in vitro. Cell growth inhibition by CFS and UV-killed L. acidophilus (ATCC 314) was studied and Western blotting and a fluoregenic assay was performed to determine IDE expression and its activity, respectively. Insulin degradation was evaluated by sandwich enzyme-linked immunosorbent assay(ELISA). IDE expression and activity was reduced by CFS and UV-killed L. acidophilus (ATCC 314). Although, decreased enzyme expression and activity was not significant for CFS in contrast to MRL (MRS with same pH as CFS). Also, reduction in IDE activity was not statistically considerable when compared to IDE expression. Insulin degradation was increased by CFS but decreased by UV-killed L. acidophilus (ATCC 314).