Common features of autoimmune diseases

This 2018 French review subject was mechanisms of autoimmunity:

“Autoimmune diseases (AIDs) encompass more than 80 distinct chronic disorders characterized by inflammatory reactions that can either be systemic or organ specific. In all cases, the disease development is the consequence of the effects of environmental factors in predisposed individuals.

Most of the genes identified by genome-wide association studies (GWAS) on AIDs are related to immunity. However, functional immune parameters that are commonly dysregulated in AIDs do not necessarily stem from these genetic variants. Rather than performing even larger GWAS, understanding complex traits, such as human diseases, may require meticulous analysis or cell-specific gene networks and take into account not only core genes but also seemingly irrelevant genes that may overall have an impact on the disease.

T_reg cell defects have been considered a primary cause of AIDs. However, one could ask whether the T_reg cell dysfunction exists before the onset of the disease or is provoked by the inflammatory event induced by the triggering components. The defect of T_reg cells generally coexists with the inflammatory processes, suggesting several hypotheses:

The inflammation might develop because of a poor regulation of the immune system,

The T_reg cells could become inefficient because of the inflammatory environment, or

A common factor concomitantly leads to both effects.

It is likely that autoimmunity results from a chronic imbalance involving both environmental and intrinsic factors. It is now clear that polygenic explanations did not fulfill expectations and that more efforts are needed to understand how the interplay of environmental clues may have a phenotypic impact.”