Immune System, Cytokines and Endometriosis

The role of the immune system in endometriosis

Key Points

Highlight:

• More studies on immune reactions may offer new therapeutic targets for patients with endometriosis.

Background:

• Endometriosis is an inflammatory disease, where interactions between endocrine and immunological systems are involved.
• The study of some cytokines as predictors or discriminators of the disease is promising.
• One possible cause for endometriosis development of endometriosis is altered immunological reactions where endometriosis cells in peritoneum initiate an inflammatory response.

Key points:

• A narrative review examining the relationship between immune cells and endometriosis initiation and progression.
• Journals published in English between 1921 and 2020 were searched, 100 articles were selected for further analysis.
• In women diagnosed with endometriosis, the activation of macrophages is enhanced, resulting in the release of more cytokines, prostaglandins, and complement.
• Natural killer cells, cytotoxic effector lymphocytes have diminished function in women diagnosed with endometriosis to ensure the survival of endometriosis cells in the peritoneal cavity.
• Compared to the control, the peritoneal fluid of women with endometriosis has higher oxidative stress, which activates macrophages resulting in increased proinflammatory mediators.
• The serum levels of IL-1, IL-4, and IL-10 are significantly higher in women with endometriosis compared to controls. These changes create an environment that facilitates the survival and proliferation of the ectopic endometrium. As a result, it is able to reach the endometrial cavity through the retrograde flow.

Conclusions:

• Endometriosis is considered to be a complex disease with immunological dysregulation.
• Studies investigating the activities of numerous cells involved in immune reactions could provide new therapeutic targets.

Lay Summary

Endometriosis is an estrogen-dependent chronic disease. Diagnosing endometriosis is difficult because the signs and symptoms vary considerably. Therefore, the discovery of a reliable non-invasive diagnostic biomarker would represent a major advance for the clinical diagnosis of endometriosis. 

It has been addressed that endometriosis is an inflammatory disease, where endocrine-immunological interactions are probably involved in the pathogenesis of the disease. The study of some cytokines as predictors or discriminators of the disease is promising.

One possible cause for the development of endometriosis is alterations in immunological reactions. This phenomenon occurs when the immune cells in the peritoneal cavity overloaded through the endometriosis cells that spread and initiate an inflammatory response.

To understand the role of the immune response in endometriosis, Dr. Nomelini group from Brazil summarized reviews regarding the influence of immune cells on the initiation and progression of endometriosis. This paper was recently published in the journal “Immunological Investigations: A Journal of Molecular and Cellular Immunology”.

For this journal, the group searched specific target keywords in journals published in English between 1921 and 2020. 100 articles were selected for further analysis.

The peritoneal fluid contains several types of cells from the immune system, including macrophages, NK cells, lymphocytes, monocytes, and mesothelial cells. In women diagnosed with endometriosis, the activation of macrophages is enhanced, and release more cytokines, prostaglandins, and complement components.

Natural killer cells, cytotoxic effector lymphocytes have diminished function in women diagnosed with endometriosis to ensure the survival of endometrial cells in the peritoneal cavity. This phenomenon causes homeostasis in the peritoneal cavity to collapse, altering other processes, such as immune responses.

Some studies have shown that, compared to the control, the peritoneal fluid of women with endometriosis has higher oxidative stress. Oxidative stress involves an imbalance between free radicals, which activate macrophages in the context of endometriosis. The enhancing oxidative stress, which, in turn, increased mediators, such as pro-inflammatory drugs, in endometriosis patients.

Cytokines play a key role in the immune system, mediating inflammatory activity. Recent studies have shown that the serum levels of IL-1, IL-4, and IL-10 are significantly higher in women with endometriosis compared to controls. These changes create an environment that facilitates the survival and proliferation of the ectopic endometrium. As a result, it is able to reach the endometrial cavity through the retrograde flow.

In conclusion, endometriosis is considered to be a complex disease with immunological dysregulation. Studies investigating the activities of numerous cells involved in immune reactions could provide new therapeutic targets.

Research Source: https://pubmed.ncbi.nlm.nih.gov/32408782/