New discovery to fight infertility: the role of M2 macrophages

Researchers at the University of Adelaide have discovered in the laboratory, from studies on mice, a fundamental mechanism that could give new outlets for the treatment of some fertility problems without having to go through assisted fertilization and therefore with significant savings.

Prof. Sarah Robertson researcher and project manager, together with her team of scientists, discovered that immune cells known as M2 macrophages are essential for fertility because they promote the production of progesterone – a hormone which, as we well know, is essential for implantation of the embryo and the onset of pregnancy.

This is a huge step forward as it opens up new techniques and ways of treating fertility problems.

We already know from previous studies that  macrophages are numerous in reproductive tissues but this is the first time that their presence seems to be necessary for   the establishment  and continuation of pregnancy.

One in six couples experience fertility problems and generally in about half of couples the cause  of infertility cannot be  established . Having the possibility to  also evaluate  the appearance of M2 macrophages could improve  fertility  with techniques and treatments that do not necessarily include in vitro fertilization.

It would be good news also for other aspects, both economic, because avoiding fertilization implies a reduction in costs, but also for the woman who would undergo much less complicated and heavy treatments.

In short, this new discovery could help to understand where fertility problems originate in women in whom apparently everything seems to be fine.

M2 macrophages are implicated in organizing rapid development of blood vessel networks in the ovaries, hence the vasculature of the copro luteum, so that enough progesterone can then be produced to sustain pregnancy. An insufficient number of M2 macrophages affect the production of progesterone, as a result it can prevent the implantation of an embryo or cause incorrect implantation which then leads to miscarriage.

In fact, researchers have demonstrated that the removal of macrophages during the first days of pregnancy causes an insufficient production of progesterone which leads to the destruction of the dense capillary network that is essential for the sustenance and support of the maturation of the corpus luteum.

This pivotal role of macrophages provides new insights into the biology of the corpus luteum and reveals that they are a potentially critical rate-limiting factor contributing to the luteal dysfunction implicated in some forms of infertility. If a similar role is confirmed in women,   macrophages may become a new target for optimal therapeutic intervention to promote ovarian function.