PTGS2 Gene May Be Involved in Women with Endometriosis Becoming Infertile, Study Reports

PTGS2 Gene May Be Involved in Women with Endometriosis Becoming Infertile, Study Reports

Lower PTGS2 gene activity in cells that surround female sex cells may play a role in women with endometriosis becoming infertile, according to a study.

The lower activity may also be a sign of the sex cells, known as oocytes, being of lower quality, researchers said. The cells that surround oocytes — which are the equivalent of sperm cells in men — are called cumulus cells.

The study, “PTGS2 down-regulation in cumulus cells of infertile women with endometriosis,” was published in the journal Reproductive Biomedicine Online.

Forty to 60 percent of women with impaired fertility have higher rates of endometriosis, and 30 to 50 percent are infertile, studies have shown. The mechanisms underlying the infertility remain unknown.

Previous research has shown that the PTGS2 gene, which produces a protein called cyclooxygenase 2 (COX-2), plays a crucial role in oocyte maturation, which is essential to fertilization. Endometriosis lesions are associated with a faulty version of the gene, the studies have indicated.

Researchers have wanted to use actual oocytes to study oocyte quality, but women rarely donate them to research. So scientists have instead studied the cumulus cells that surround oocytes.

The objective of the new PTGS2 study was to compare the genes’ activity levels in infertile women, some with endometriosis and some without, who were having their ovaries stimulated to receive an intracytoplasmic sperm injection. The injection involves placing one sperm into a mature egg to try to overcome fertilization problems.

Researchers analyzed PTGS2 gene levels in cumulus cells collected from 38 infertile patients with endometriosis and 40 infertile patients without the disease.

Infertile women with endometriosis had lower levels of PTGS2 activity than the controls, the team discovered.

“In summary, to the best of our knowledge, the present data demonstrate for the first-time a [reduction] of PTGS2 in cumulus cells of infertile patients with endometriosis, compared with infertile controls,” researchers wrote. “We hypothesize that lower levels of COX-2 in cumulus cells might be involved in the impairment of oocyte development.”

This suggests “a possible mechanism involved in disease-related infertility which needs to be evaluated in future studies with larger numbers of enrolled participants, and with suitable methodologies,” they wrote.