Testing Probiotics for Their Ability to Promote Pan-creatic Beta Cell Regeneration Using A Microscale In Vivo Model of Diabetes Based on Transgenic Zebrafish

Background: Diabetes – both type 1 and advanced type 2 – is a disease characterized by an absolute or relative deficiency of pancreatic beta cells. Therefore, replenishing the lost beta cell function or absolute beta cell mass is a strategy to allevi-ate some of the burdens of the disease. One of the possible ap-proaches to replenish beta cells is the induction of endogenous regeneration. It has been observed that probiotics modulate the microbial composition of the gut and can also modify host nu-trient metabolism and energy homeostasis. The microbiome is known to influence the progression of T1DM, and altering the microbiome may therefore be a strategy to delay onset or man-age T1DM pathogenesis. Three main targets have emerged for probiotic therapy in T1DM: reduction or redirection of auto-immunity, increased β-cell proliferation, and decreased β-cell apoptosis.Materials and Methods: The zebrafish pancreas shares a basic structure and cellular makeup with the mammalian pancreas, implying that the developmental lessons we learn in zebrafish will be broadly applicable. The ability to manipulate resident microbes in the larval zebrafish, combined with the optical transparency and sophisticated genetic tools of the zebrafish model, make it a powerful platform to investigate this ques-tion. In our ongoing biodiscovery program to identify bacterial secondary metabolites with pancreatic beta cell regeneration-promoting activity, we are using a transgenic zebrafish model of T1DM. This model is based on Tg(ins:cfp-nfsb) larvae with pharmacologically inducible cell-specific ablation of pancreatic beta cells by the prodrug nifiprinol, which is metabolized by bacterial nitroreductase to cause apoptosis in pancreatic beta cells.Results: After incubating larvae with each probiotic strain for 96 hours, fluorescence and confocal microscopy verified the re-generation of beta cells in the larvae of each experimental group and in comparison with positive and negative controls. Using this bioassay, we have to date identified at least one of our pro-biotic strains as having ability to increase beta cell mass. Active strains and their selected primary metabolites, e.g. short-chain fatty acids (SCFAs) will next be screened and analyzed using qRT-PCR of beta cell markers, immunohistochemistry analysis and a free glucose assay in order to verify both the function and the identity of regenerated beta cells.Conclusion: Additional tests in higher animal models will help determine which of these probiotics and their metabolites have therapeutic potential for T1DM. Research in animal models and humans has provided evidence suggesting possible sign-aling pathways that can be influenced by probiotics and their metabolites, triggering proliferation and function of pancreatic beta cells directly and indirectly by production/fermentation of short chain fatty acids (SCFAs) and gamma amino butyric acid (GABA), and by stimulating the secretion of incretin hormones such as GLP-1 from entero-endocrine L-cells. Towards this end, further research will focus on the characterization of the signalling pathways involved in the regeneration of beta cells stimulated by our active probiotic strains.

کلیدواژه ها:

Type 1 Diabetes ، Probiotics ، Zebrafish ، Glucagon-Like Peptide-1 (GLP-1) ، Short Chain Fatty Acids (SCFAs)