Emerging role of air pollution in autoimmune diseases

Autoimmune diseases (ADs) are a broad spectrum of disorders featured by the body's immune responses being directed against its own tissues, resulting in prolonged inflammation and subsequent tissue damage. Recently, the exposure to ambient air pollution has been implicated in the occurrence and development of ADs. Mechanisms linking air pollution exposures and ADs mainly include systemic inflammation, increased oxidative stress, epigenetic modifications induced by exposures and immune response caused by airway damage. The lung may be an autoimmunity initiation site in autoimmune diseases (ADs). Air pollutants can bind to the Aryl hydrocarbon receptor (AHR) to regulate Th17 and Treg cells. Oxidative stress and inducible bronchus associated lymphoid tissue caused by the pollutants can influence T, B cells, resulting in the production of proinflammatory cytokines. These cytokines stimulate B cell and dendritic cells, resulting in a lot of antibodies and self-reactive T lymphocytes. Moreover, air pollutants may induce epigenetic changes to contribute to ADs. In this review, we will concern the associations between air pollution and immune–inflammatory responses, as well as mechanisms linking air pollution exposure and autoimmunity. In addition, we focus on the potential roles of air pollution in major autoimmune diseases including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), and type 1 diabetes mellitus (T1DM).