Host Microbe Biology

The Microbiome and MAIT Cells Play a Role in the Development of Type 1 Diabetes

Mucosal associated invariant T cells, better known as MAIT cells, found in the blood, liver, lungs, and mucosa, may be able to be used as precursor markers for Type 1 diabetes (T1D) say researchers at the Necker-Engants Malades Hospital in France.  Both blood samples from human patients and animal models showed that MAIT cells are altered before T1D develops.  The exact role the microbiome plays in causing or responding to that alteration has not yet been determined, but the microbiome is definitely affected once T1D becomes full blown.

T1D develops after the immune system attacks the beta cells in the pancreas and destroys them.  The researchers, led by Agnes Lehuen and Jacques Beltrand, found that MAIT cells, which are part of the innate immune system and regulate mucosal (including gut mucosal) homeostasis, showed alterations, including increases in granzyme B, before T1D developed.  MAIT cells are activated by precursors of bacterial riboflavin presented by the major histocompatibility complex (MHC) class 1-related molecule MR1.  MAIT cells did not activate in non-obese diabetic (NOD) mice that were deficient in MR1, and the guts of these mice lost integrity and produced substances that increased the kind of autoimmune activity typical of exacerbated Type 1 diabetes.

The authors concluded that monitoring MAIT cells might be a way to anticipate the onset of T1D, and MAIT cell manipulation might represent a new therapeutic strategy for the disease.

Islets of Langerhans & Diabetes Mellitus Type 1

For more information, go the October 9 issue of Nature Immunology; DOI: 10.1038/ni.3854 (Epub ahead of print).