Fc receptors gone wrong: A comprehensive review of their roles in autoimmune and inflammatory diseases

Systemic autoimmune and inflammatory diseases have a complex and only partially known pathophysiology with various abnormalities involving all the components of the immune system. Among these components, antibodies, and especially autoantibodies are key elements contributing to autoimmunity. The interaction of antibody fragment crystallisable (Fc) and several distinct receptors, namely Fc receptors (FcRs), have gained much attention during the recent years, with possible major therapeutic perspectives for the future. The aim of this review is to comprehensively describe the known roles for FcRs (activating and inhibitory Fc gamma Rs, neonatal FcR [FcRn], Fc alpha RI, Fc epsilon Rs, Ro52/tripartite motif containing 21 [Ro52/TRIM21], Fc delta R, and the novel Fc receptor -like [FcRL] family) in systemic autoimmune and inflammatory disorders, namely rheumatoid arthritis, Sjo center dot gren's syndrome, systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathies, mixed con-nective tissue disease, Crohn's disease, ulcerative colitis, immunoglobulin (Ig) A vasculitis, Behcet's disease, Kawasaki disease, IgG4-related disease, immune thrombocytopenia, autoimmune hemolytic anemia, anti-phospholipid syndrome and heparin-induced thrombocytopenia.

Automated summary

Systemic autoimmune and inflammatory diseases are complex and only partially understood, involving abnormalities in various components of the immune system. Antibodies, particularly autoantibodies, play a key role in autoimmunity. The interaction between antibody fragment crystallisable (Fc) and Fc receptors (FcRs) has attracted much attention recently, with potential therapeutic prospects in the future. This review comprehensively describes the roles of known FcRs in systemic autoimmune and inflammatory disorders, including rheumatoid arthritis, Sjögren's syndrome, systemic lupus erythematosus, and other related diseases.