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How do autoimmune illnesses result from viral infections?

The different ways that viruses affect the development of AIDs have been the subject of decades of research, but the connection between these two illnesses is extremely complicated and continually changing.

Around 5% of the world’s population is affected by AIDs, which is caused by immunological responses that are dysregulated and may persist for a long time, cannot be downregulated, or are more intense than necessary.

Irritable bowel syndrome (IBS), multiple sclerosis (MS), and type 1 diabetes are examples of AIDs that are often categorized by the specific organs they affect. Systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjögren syndrome are examples of conditions that show that AIDs can also be systemic.

Many autoimmune disorders are influenced by genetic factors, however the majority of autoimmune diseases are brought on by a both genetic and non-genetic variables combined. In addition, the immune system can be negatively impacted by environmental variables like infections, toxic chemicals, and dietary composition, which can make some people more susceptible to contracting AIDS.

Autoimmunity is also more likely in those with persistent viral infections. In fact, a greater proportion of AIDs diagnoses in these patients have been observed in conjunction with the rising number of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections that have been identified throughout the coronavirus disease 2019 (COVID-19) pandemic.

When the immune system loses its ability to tolerate the activity of self-antigens, autoimmune diseases can occur. The two different mechanisms by which this loss of immunological tolerance can arise through altered central tolerance selection or insufficient peripheral suppressive functions.

Central tolerance refers to the different selection processes that exist in the thymus and bone marrow to remove autoreactive T- and B-cells, respectively, before they leave this organ and enter the bloodstream. Previous studies have shown that viral thymus infections, such as those caused by roseoloviruses, can interrupt the maturation and selection of T-cells and, as a result, lead to autoimmunity.

Despite the effectiveness of central tolerance, some reactive T- and B-cells can still enter the bloodstream and join the peripheral lymphocyte pool. At this point, peripheral tolerance is responsible for limiting the duration, intensity, and location of immune responses through various immune cells, the most prominent of which include regulatory T-cells (Tregs). Notably, Treg dysfunction is associated with various autoimmune diseases, including type 1 diabetes, RA, MS, SLE, and myasthenia gravis.