New groundbreaking research, conducted at the University of Adelaide, reveals that immune cells called “macrophages” are responsible for the production of the hormone progesterone, essential for establishing pregnancy.
A macrophage is a type of white blood cell that engulfs and then digests foreign material. Macrophages play a major role in the human body’s immune response to foreign invaders, such as pathogens (organisms that do us harm). They are highly specialized in the removal of dying or dead cells and cellular debris. Macrophages are normally found in connective tissue, the liver and spleen.
The result of the study, published in the Journal of Clinical Investigation, provides invaluable insight into new possible ways of treating female infertility.
The team conducted lab studies that illustrated just how vital macrophages are for creating a healthy hormone environment in the uterus.
Professor Sarah Robertson, NHMRC Principal Research Fellow and member of the University’s Robinson Institute, led the study. She said that while previous research has shown that macrophages are found in reproductive tissues, “this is the first time that their absolute necessity for pregnancy has been demonstrated.”
Macrophages organize the blood vessel networks in the ovary, promoting the production of the hormone progesterone, “which is the major hormone for initiating pregnancy.”
Women with a low number of macrophages lack sufficient levels of the hormone progesterone, which can cause poor embryo development – increasing the risk of miscarriage.
Professor Robertson said:
“The contribution of macrophages to the healthy vascular structure of the corpus luteum, which must develop rapidly in a matter of days to produce high levels of progesterone, was a surprise. This is the first time that we have understood how pivotal macrophages are for conception and establishing pregnancy.
Environmental factors such as infection, obesity and stress all contribute to inflammatory responses and affect the generation and function of macrophages in women. This could therefore impact on the macrophages’ ability to support pregnancy.”
Treatment with progesterone may be able to reverse the effects of low levels of macrophages, according to the lab studies.
Professor Robertson said that one of the main causes of female infertility is insufficient progesterone. Many infertile women are now “routinely provided with progesterone supplements as part of their assisted reproductive treatments, and this is also a promising therapy for recurring miscarriage.”
However, “if macrophages are shown to play the same role in women as we’ve seen in our laboratory studies, this gives us potential new avenues for targeting them with lifestyle and nutritional intervention, improving fertility by advancing the quality of the conception environment.”
Written by Joseph Nordqvist