Levels of key immune-signaling molecules within the vagina “undergo clear and consistent” fluctuations in the course of the menstrual cycle, a UW Medicine-led team reports in a study published today within the journal BMC Medicine.

The findings might help researchers higher understand the immune system’s role in fertility, and guide scientists’ efforts to develop vaccines and coverings for infectious disease.

A meta-analysis of 32 studies showed that the immune system throughout the vagina ebbs and flows, depending on menstrual-cycle stage. The evaluation identified 53 distinct messages that immune cells sent to at least one one other.

Cells within the body refer to one another by making molecules called cytokines, which may tell other immune cells that “there’s an infection here” or “no worries, every part’s tremendous,” said lead creator Sean Hughes, a research scientist in obstetrics and gynecology on the University of Washington School of Medicine.

The study’s principal goal was to construct a world view of the immune-related communication within the vagina and cervix in the course of the the menstrual cycle, Hughes said. Certainly one of the study’s more consistent findings was that cytokines “call” macrophages to the vaginal area more in the course of the span before the egg is released from the ovary (the follicular phase) and fewer after the egg is released (the luteal phase), when conception occurs.

In practical terms, this discovery suggests that researchers should consider the menstrual-cycle stage of patients or study participants when testing a latest vaccine or conducting other investigations, Hughes said.

“The decreases we observed in lots of cytokines in the course of the luteal phase are consistent with prior claims that immunity wanes in the course of the luteal phase. This probably happens to make it easier for an embryo to implant,” the authors wrote. “In compensation, it seems that antimicrobial aspects, corresponding to beta-defensins, increase in the course of the luteal phase.”

Scientists must design their studies to be sure that that every one participants get measured at the identical stage of the cycle.”

Dr. Florian Hladik, Senior Creator, UW Research Professor of Obstetrics and Gynecology

The study provides a powerful reference point as to what happens in the course of the cycle, Hughes said.

“We have now the ‘what’ information for 53 different cytokines now. For every one, we want to search out out why that is happening, and the way this pertains to sexually transmitted diseases and pregnancy.”

Overall, the difference between the follicular and luteal phases might mean that vaccinations and other interventions can be more practical in a single phase than one other, Hughes suggested.

Source:

University of Washington School of Medicine/UW Medicine

Journal reference:

Hughes, S.M., et al. (2022) Changes in concentrations of cervicovaginal immune mediators across the menstrual cycle: a scientific review and meta-analysis of individual patient data. BMC Medicine. doi.org/10.1186/s12916-022-02532-9.