Scientists have found that a set of bacteria in our body, known as microbiota, can also protect us against the development of type 1 diabetes.

A research team comprising of Inserm, Paris Descartes University and the CNRS through collaboration with teams from China and Sweden, and coordinated by Julien Diana is focusing on a category of antimicrobial peptides, i.e. cathelicidins.

Apart from their protective function, these peptides have also exhibited immunoregulatory abilities against several autoimmune diseases. As such, scientists hypothesise that cathelicidins may be involved in the control of type 1 diabetes, an autoimmune disease where certain cells in the immune system attack beta cells in the pancreas which secrete insulin.

To combat pathogens, the immune system has developed various mechanisms to detect, defend against and even destroy micro-organisms that are harmful to the body. This includes antimicrobial peptides and natural proteins that destroy pathogenic bacteria by disrupting their cellular membrane. Not only are they produced by immune cells, they are also produced by cells whose functions are not immune-related. Injecting cathelicidins inhibit the development of pancreatic inflammation and, as such, suppressed the development of autoimmune disease in mice, states Julien Diana.

Since the production of cathelicidins is controlled by short-chain fatty acids produced by gut bacteria, scientists are studying the possibility that this may be the cause of the cathelicidin deficiency associated with diabetes.

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.

The research is published in the Immunity journal.