Figure 4.

Model summarising the role of cathelicidin in the interplay between the pancreas and the gut. Short-chain fatty acids (SCFA) are produced by the gut microbiome during alimentary fibre fermentation, stimulating the expression of cathelicidin in the epithelial lining of the gut. SCFA stimulates the expression of cathelicidin by pancreatic islets, which reciprocally control and modulate the bacterial growth in the gut, preventing gut microbiome dysbiosis. Cathelicidin expression in the β cell is also induced in the presence of high glucose concentration and may also be induced by vitamin D, as seen in other cell types. Extracellular cathelicidin stimulates insulin granule exocytosis via the epidermal growth factor receptor (EGFR). It is not completely elucidated if intracellular cathelicidin can also induce insulin release directly. Cathelicidin expression also induces the prevalence of regulatory T cells (T-regs) and M2 macrophages which are associated with a lower risk of type 1 diabetes development.