Endometriosis is a prevalent and debilitating condition that affects 10% of women globally, often resulting in chronic pain, fatigue, and pain during sexual activity, among other symptoms. However, despite its high prevalence, women in the UK typically wait an average of 7.5 years to receive a diagnosis, leaving them untreated and vulnerable to further health complications such as organ damage and infertility.
Since endometriosis is a complex disease that affects various parts of the body, scientists have yet to fully comprehend all of its underlying causes, making it difficult to develop a cure. Nevertheless, recent research has uncovered a potential link between endometriosis and the immune system. While the exact nature of this connection remains unclear, investigating it further could lead to more targeted treatments for this condition.
Inflammation and immunity
To comprehend the link between endometriosis and our immune system, it’s crucial to understand the process of inflammation, a vital aspect of our immune system.
Inflammation is the body’s response when encountering a harmful pathogen like bacteria or virus. The immune system secretes cytokines, special proteins that communicate with immune cells, instructing them on what to do.
Inflammation’s symptoms vary based on why immune cells are mobilized. For instance, a cut on the finger may cause redness, swelling, and warmth as the immune system combats pathogens and fixes the wound. Meanwhile, flu-like symptoms may arise from inflammation caused by a virus.
Typically, inflammation is a brief process. However, the immune system can malfunction, causing it to send inflammatory cells and cytokines even when there’s no threat. In autoimmune diseases like rheumatoid arthritis, the immune system attacks the body, leading to long-term inflammation in the joints.
Inflammation is a natural aspect of the menstrual cycle.
The menstrual cycle has two phases: the follicular phase (from the onset of menstruation to ovulation) and the luteal phase (from ovulation until the start of menstruation). The majority of inflammation during the menstrual cycle is found in the uterus, but changes may occur throughout the body.
During the follicular phase, oestrogen levels increase, encouraging the uterine lining to thicken in preparation for a fertilized embryo. However, certain immune cells have specific oestrogen receptors, prompting them to trigger an immune response, readying the body to combat any foreign invaders in case of pregnancy. Consequently, women are less prone to infections during the follicular phase, but those with autoimmune diseases may experience increased symptoms.
To avoid rejecting a fertilized egg, the immune system is suppressed during the luteal phase, increasing the risk of infection and potentially relieving some autoimmune symptoms.
Endometriosis and immunity
Numerous studies have identified immune system changes in individuals with endometriosis. For instance, research has shown that patients with the condition have elevated levels of inflammation, specifically higher levels of cytokines. In addition, natural killer cells, which play a crucial role in fighting viruses and tumours, function more poorly in people with endometriosis. The uterine lining in endometriosis patients also produces excess chemokines, which attract other immune cells and exacerbate inflammation.
It remains unclear whether immune system dysfunction causes endometriosis or is simply a symptom of the disease. However, this dysfunction could help explain the suspected association between endometriosis and autoimmune disorders like rheumatoid arthritis, lupus, and inflammatory bowel disease.
Elevated inflammation levels can also lead to worse symptoms during infections, such as COVID-19. Studies have found that women with endometriosis who contract COVID-19 experience more severe symptoms than those without the condition. Additionally, COVID-19 may worsen endometriosis symptoms, particularly pelvic pain, depression, fatigue, and gastrointestinal issues. Recent research has even found that women with endometriosis are 22% more likely to suffer from long COVID, and their symptoms may last longer.
Understanding the link between the immune system and endometriosis could lead to improved treatments or even a cure for the disease. However, research into endometriosis is severely under-funded, and diagnosis times are significantly longer than for other chronic conditions like asthma or diabetes. Greater priority must be placed on researching endometriosis and its causes to provide new insights and better treatments for the millions of women affected by the disease.