How Microbiota Protects against Development of Type 1 Diabetes

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A pancreatic islet of Langerhans expressing the immunoregulator antimicrobial peptide CRAM (in red). The insulin-producting beta-cells are in green and the glucagon-producting alpha-cells are in blue. Credit: © Julien Diana

A pancreatic islet of Langerhans expressing the immunoregulator antimicrobial peptide CRAM (in red). The insulin-producting beta-cells are in green and the glucagon-producting alpha-cells are in blue. Credit: © Julien Diana

 

A category of antimicrobial peptides, cathelicidins and being researched by a team coordinated by Julien Diana, Inserm Research Fellow at Inserm Unit 1151 is focusing on. Apart from their protective function, these peptides have also exhibited immunoregulatory abilities against several autoimmune diseases.

They observed that beta pancreatic cells in non-diseased mice produce cathelicidins and that, interestingly, this production is impaired in diabetic mice.”Injecting cathelicidins inhibits the development of pancreatic inflammation and, as such, suppresses the development of autoimmune disease in these mice” states Julien Diana.

Given that the production of cathelicidins is controlled by short-chain fatty acids produced by gut bacteria, Julien Diana’s team are studying the possibility that this may by the cause of the cathelicidin deficiency associated with diabetes. Indeed, researchers have observed diabetic mice have a lower level of short-chain fatty acids than that found in healthy mice. By transferring part of the gut bacteria from healthy mice to diabetic mice, they are re-establishing a normal level of cathelicidin. Meanwhile, the transfer of micro-organisms reduces the occurrence of diabetes.

“….this research is further evidence of the undeniable role microbiota plays in autoimmune diseases, particularly in controlling the development of autoimmune diabetes.” Preliminary data, as well as scientific literature, suggest that a similar mechanism may exist in humans, paving the way for new therapies against autoimmune diabetes. http://presse-inserm.fr/en/bacteria-that-prevents-type-1-diabetes/20118/