As researchers continue to look for environmental factors that cause autoimmune disease, many are turning the lens towards the human body itself, and to vast networks of microbial communities that dwell in and on it.
Humans are host to an array of microscopic life. At several trillion strong, microbial communities consisting of bacteria, fungi, protozoa, and viruses occupy numerous parts of the body. Their genetic material is collectively known as the microbiome. These microbes may be up to two times more prevalent than human cells, and each person’s microbiome could weigh as much as 5 pounds (1, 2).
“Imbalances in the microbiome may be
an activator for disease.”
Microbial colonies support human health in a variety of ways. The gut microbiota is involved in nutrient digestion, vitamin synthesis, and several other metabolic processes. It also influences the development and maintenance of the immune system (2).
Just as the microbiome is thought to be essential to human health, some studies suggest that imbalances in the microbiome may be an activator for disease—including autoimmune conditions.
Alterations in the microbiome, broadly referred to as dysbiosis, can result from a variety of factors, including diet, toxins, pathogens, and more. Pathogens that attack the intestines are the most influential in promoting microbial dysbiosis. In animal studies, researchers have observed that foodborne viral pathogens can alter the composition of the microbiome, trigger inflammation, and contribute to the development of autoimmunity (3).
Researchers have yet to determine which specific microbiota are directly involved in the regulation of inflammatory mechanisms. However, many believe that bacteria found in the mucus layer of the intestines may hold the key to understanding more about how the microbiome relates to health and disease.
While further investigation is needed, many researchers suspect that autoimmune diseases, as well as some other chronic conditions, could have their origins in the gut microbiome (2, 3). Scientists are currently studying the relationship between gut microbe health and the following autoimmune diseases:
Data strongly suggests that there is some degree of interplay between autoimmune disease and gut microbiome health. However, more research is necessary to determine whether abnormalities in the gut microbiome are a cause of autoimmune disease, an effect, or both [6, 7].
As scientists continue to investigate this complex relationship, many are hopeful that studies of the microbiome could one day give way to improvements in diagnostics and therapies- and possibly even in the prevention of some autoimmune diseases.
For more about the microbiome, check out our previous article, What Is the Microbiome?
Abbott, A. (2016). Scientists Bust Myth That Our Bodies Have More Bacteria Than Human Cells. Nature.
Hair, M., Sharpe, J. (2014). Fast Facts About the Human Microbiome. The Center for Ecogenetics and Environmental Health, University of Washington.
Xu, Huihui, et al. (2019). The Dynamic Interplay between the Gut Microbiota and Autoimmune Diseases. National Center for Biotechnology Information, U.S. National Library of Medicine, 2019, 7546047. https://doi.org/10.1155/2019/7546047
Carding, S., et al. (2015). Dysbiosis of the Gut Microbiota in Disease. National Center for Biotechnology Information, U.S. National Library of Medicine.
Hofheinz, E. (2019). To Understand Lupus, Study the Gut. The Rheumatologist.
Henke, M. T., et al. (2019). Ruminococcus gnavus, a Member of the Human Gut Microbiome Associated with Crohn’s Disease, Produces an Inflammatory Polysaccharide. Proceedings of the National Academy of Sciences of the United States of America.
Zhou, H., et al. (2020). Evaluating the Causal Role of Gut Microbiota in Type 1 Diabetes and Its Possible Pathogenic Mechanisms. Frontiers in Endocrinology.
Jangi, S., et al. (2016). Alterations of the Human Gut Microbiome in Multiple Sclerosis. Nature.
Wu, X. et al. (2017). Alterations of the Gut Microbiome in Rheumatoid Arthritis. Osteoarthritis and Cartilage.
Manasson, J., Blank, R. B., Scher, J. U. (2020). The Microbiome in Rheumatology: Where are We and Where Should We Go?. BMJ Journals.