Increased circulating anti‐α6‐integrin autoantibodies in psoriasis and psoriatic arthritis but not in rheumatoid arthritis

In psoriatic skin, laminin integrity is altered, which could lead to insufficient laminin integrin interactions, leaving the α6‐integrin exposed and possibly accessible for autoantibody production. Therefore we investigated the presence of anti‐α6‐integrin autoantibodies in the serum of patients with psoriasis vulgaris (Ps), psoriatic arthritis (PsA) and rheumatoid arthritis (RA) in comparison with healthy donors. The level of circulating anti‐α6‐integrin antibodies was determined by enzyme‐linked immunoassay using α6‐integrin fragments. Antibodies against at least one recombinant fragment were found in approximately 30% of Ps and PsA patients. In contrast, in RA patients, the frequency of antibodies was similar to healthy controls. Our study shows the presence of anti‐α6‐integrin antibodies in Ps and PsA but not in RA, which could indicate ongoing abnormal processes in the skin. Anti‐α6‐integrin autoantibodies may contribute to the formation of micro‐wounds in the skin and to the characteristic wound‐healing phenotype in psoriasis.