Goodpasture's disease: molecular architecture of the autoantigen provides clues to etiology and pathogenesis.

Purpose of review—Goodpasture’s (GP) disease is an autoimmune disorder characterized by the deposition of pathogenic autoantibodies in basement membranes of kidney and lung, which induces rapidly progressive glomerulonephritis and pulmonary hemorrhage. The target antigen is the α3NC1 domain of collagen IV, which is expressed in target organs as aα345 network. Recent studies of specificity and epitopes of GP autoantibodies and discovery of novel posttranslational modification of the antigen, a sulfilimine bond, provide further insight into mechanisms of initiation and progression of GP disease. Recent findings—Analysis of the specificity of GP autoantibodies revealed distinct subset of circulating and kidney-bound anti-α5NC1 antibody, which is associated with loss of kidney function. Structural integrity of the α345NC1 hexamer is stabilized by the novel sulfilimine crosslinks conferring immune privilege to the GP autoantigen. Native antibodies may contribute to establishment of immune tolerance to autoantigen. Structural analysis of epitopes for autoantibodies and alloantibodies indicates a critical role of conformational change in the α345NC1 hexamer in eliciting of autoimmune response in GP disease. Summary—Understanding of the quaternary structure of the GP autoantigen continues to provide insights into autoimmune mechanisms that serve as a basis for developing of novel diagnostic tools and therapies for Goodpasture’s disease.