The study, published in Science​​, suggests that exposure to gut microbes and sex hormones exert ‘potent effects’ on autoimmune diseases – such as multiple sclerosis, rheumatoid arthritis, and lupus – many of which are more prevalent in women.

Led by principal investigator Dr. Jayne Danska from the The Hospital for Sick Children, Canada, the research team also found that when female mice at high risk of autoimmune (type 1) diabetes were exposed to normal gut bacteria from adult male mice, they were strongly protected against the disease.

In the mouse strain used by the team, more than 85% of females develop autoimmune diabetes due to a strong genetic risk factors, however, only 25% of the females developed the disease after being given normal male gut microbes early in life.

“Our findings suggest potential strategies for using normal gut bacteria to block progression of insulin-dependent diabetes in kids who have high genetic risk,”​ suggested Danska.

The lead scientist added that a further ‘unexpected’ finding was the effects of the gut microbe treatments on sex hormone levels: “We were surprised to see that when young female mice received normal gut microbes from adult males, their testosterone levels rose,”​ she explained, adding that the team then found that the increased levels of testosterone seen when given the male microbes was essential for protection against the autoimmune disease.

“It was completely unexpected to find that the sex of an animal determines aspects of their gut microbe composition, that these microbes affect sex hormone levels, and that the hormones in turn regulate an immune-mediated disease,”​ Danska said.

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Source: Science​

Published online ahead of print, doi: 10.1126/science.1233521​

"Sex Differences in the Gut Microbiome Drive Hormone-Dependent Regulation of Autoimmunity"​

Authors: Janet G. M. Markle, Daniel N. Frank, Steven Mortin-Toth et al​