An enzyme has been identified that may be the culprit leading to the condition known as endometriosis, a common cause of infertility and pelvic pain in women. In endometriosis, tissue identical to the inner lining of the uterus appears in patches on other parts of the body, outside the cavity of the womb. The condition causes intense pain and afflicts about 15% of women during the years between menarche (onset of menstruation) and menopause. But the condition doesn't just cause pain; it can also lead to infertility, with half of all infertile women affected by endometriosis.
Scientists at the University of Liverpool found that an enzyme that in healthy subjects is found only in sperm, egg cells, and in the inner lining of the uterus is released by the cells of the uterine lining just before menstruation in women with endometriosis. This enzyme, known as telomerase, is sometimes found in cancer cells and may be responsible for the replication of DNA sequencing during chromosomal cell division.
Lead scientist for the study, Dr Dharani Hapangama, from the University’s Department of Reproductive and Developmental Medicine, explained that the cells of the inner lining of the uterus are called endometrial cells. A woman with endometriosis sheds these cells during menstruation and expels them into her abdominal cavity. If these cells manage to thrive in this foreign environment and implant themselves into the pelvis and abdomen, the result is severe pain and possible infertility.
All chromosomes have an end section called the telomere which prevents chromosomal destruction during cell division. The telomere is longer in those women afflicted with endometriosis. Menstruation tends to cause the telomeres to become shorter and shorter as the cycles of cell division are completed, until they are so short they can no longer divide. Telomerase has the ability to extend the length of these telomeres so as to enable them to continue their role in cell division. This is what happens in sperm and egg cells, but is not a usual occurrence in the cells found in the body's organs.
Dr. Hapangama's team found that the endometrial cells are unique in their ability to secrete telomerase at the beginning of menstruation when cell division is critical, but hold back from secretion of the enzyme at the later stages of a woman's menstrual cycle, when the body is focused on the implantation of a fertilized embryo.
“Women who have endometriosis express this enzyme in both the early and late stages of the menstrual cycle which means that the cells will continue to divide and lose their ‘focus’ in supporting the establishment of a pregnancy. As a result the lining of the womb may be more hostile to an early pregnancy, and the cells that are shed at this late stage in the menstrual cycle may be more ‘aggressive’ and more able to survive and implant outside the uterus, causing pain in the pelvic or abdomen area,” said Dr. Hapangama.
Researchers hope these findings can help scientists develop new diagnostic tests and treatments for endometriosis.