How to ensure that a pregnancy goes in the best possible conditions? Researchers at the University of British Columbia (UBC) in Canada reveal the importance of the thymus, an immune system gland located at the base of the neck. According to the study they published on December 23 in the journal Nature, a good thymus health would guarantee a healthy pregnancy.

Indeed, this organ would first ensure that the maternal immune system adapts to the presence of the fetus and does not reject it by triggering a miscarriage. Then, it would also ensure that the mother does not suffer from gestational diabetes thanks to good control of her metabolism.

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Sex hormones and thymus

For this study, the researchers started from an observation: the sex hormones of pregnant women induce important changes in the thymus. They even force it to produce specialized cells, T cellsreg, which help to cope with physiological changes in pregnancy.

Their hypothesis related to a structure of the thymus: the RANK, a receptor which would be the key to the functioning of T cells.reg. “We knew that RANK was expressed in the thymus, but its role in pregnancy was unknown“, explains Dr. Josef Penninger, professor in the department of medical genetics at UBC, in a university press release.

More miscarriages …

To understand its role, the researchers then studied mice to which the RANK had been deleted from the thymus. Result, in these mice: the thymus does not produce T cellsreg, therefore the rate of Treg in the placenta is very low and the number of miscarriages is very high. Why ? A priori because in this case, the immune system does not adapt to the presence of the fetus.

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The good condition of the thymus could therefore be a protective factor against miscarriages, say the researchers.

… And gestational diabetes

But that’s not all. Scientists also found that mice without RANK had high levels of glucose and insulin in the blood. These indicators suggest a role for RANK on metabolism, and in particular on gestational diabetes, a form of diabetes that appears in 15% of pregnant women.

A lead that researchers have already verified in pregnant women: those who suffer from gestational diabetes had a reduced number of T cells, according to themreg in the placenta, such as mice lacking RANK.

An “active and dynamic” body

“NOTour work over several years has allowed (…) to discover a new paradigm for the function (of the thymus)“summarizes Dr Penninger.
According to him, this new study “changes our view of the thymus as an active and dynamic organ necessary for the safety of pregnancies“and could pave the way for new avenues of treatment for miscarriages and gestational diabetes.