Disrupted paternal microbiota: unhealthy young
Male mice suffering from an imbalanced gut microbiota at the time of mating reportedly produce offspring with serious health problems. This is the surprising result of a study recently published in the prestigious journal Nature.
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Should a man wishing to have children postpone conception if he has been prescribed antibiotics, which are likely to cause gut dysbiosis?
It is quite possible, according to a new study 1 that, for once, highlights men's responsibility for the future health of their offspring. Conducted on mice, this study shows that males suffering from dysbiosis at the time of mating father unhealthy offspring. Fortunately, when the microbiota is rebalanced, this transmission no longer occurs.
Transgenerational effects of gut dysbiosis
To reach this discovery, researchers at the European Molecular Biology Laboratory 2 in Heidelberg and Rome exposed male mice to 6 weeks of antibiotics. The aim was to induce (sidenote: Dysbiosis Generally defined as an alteration in the composition and function of the microbiota caused by a combination of environmental and individual-specific factors. Levy M, Kolodziejczyk AA, Thaiss CA, et al. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232. ) in the mice. They then mated them with healthy females, and the litters were analyzed after 3 weeks.
The result: compared to the offspring of fathers without dysbiosis (controls), mouse pups conceived by "dysbiotic" fathers:
- had a lower birth weight (a risk factor for diseases such as diabetes),
- suffered more from stunted growth,
- had a higher mortality rate in the first 2 months.
To explain these surprising results, the scientists analyzed the reproductive systems of the antibiotic-treated males.
A direct impact on placental development
They noted that their testes had reduced size and sperm count and showed significant hormonal and metabolic changes. The sperm showed differences in certain molecules involved in the development of the placenta.
These data prove that the microbiota and germlines (the cells that transform into sperm) communicate with each other, and that there is therefore a "gut-sperm axis."
- When analyzing the placentas of females mated with dysbiotic males during gestation, the researchers noted:
- poor placental vascularization, which could explain certain abnormalities in the offspring;
- the presence of markers similar to those of pre-eclampsia, a disease linked to abnormal placental development, responsible for intra-uterine growth restriction.
Towards a better pregnancy?
This is the first time that this kind of effect of the microbiota on the male reproductive system has been demonstrated in mammals.
Is there also a gut-sperm axis in humans? As yet, this has not been confirmed, and further studies will have to be carried out.
Considering that our lifestyles are likely to cause dysbiosis (poor diet, pollution, medications, etc.), proof of the existence of such an axis could pave the way for innovative approaches to ensure better reproductive health and more optimal pregnancies.
