Genome Instability and Somatic Mutagenesis in Autoimmune Diseases

The adaptive immune system plays a vital role in protecting individuals against invading pathogens primarily through its ability to discern self- versus non-self-antigens. Conditions leading to the breakdown of such immune surveillance can have devastating consequences, one of them being erroneous recognition and immune response against self-antigens, resulting in autoimmunity. Autoimmune diseases (AID) are widespread and span multiple organ systems and cellular functions. Historically, the etiology of AID is multifarious and complex owing to a mix of genetic predisposition and environmental conditions. However, in recent years the study of somatic mutations has gained traction in understanding the basis of AID. Somatic mutations commonly result from elevated DNA damage and inefficient DNA repair and have been linked to cancer. Moreover, the hyper-inflammatory microenvironment is highly conducive to the accumulation of DNA damage in immune cells. Thus, understanding the mutational burden and landscape of somatic mutagenesis in the context of AID can illuminate the basis of disease development and progression. In this review, we summarize past and current research on genome instability in AID, focusing on the nexus between inflammation, immune response, DNA damage, and mutagenesis, and discuss the possible link between AID and cancer development. We provide examples of autoimmune disorders that have been studied from a mutational standpoint and outline results from key studies highlighting the extent of DNA damage and mutagenesis in cells from AID patients. Lastly, we provide our perspective on the key challenges and future directions to understand the role of somatic mutagenesis in autoimmunity and cancer.