Sjögren's syndrome--study of autoantigens and autoantibodies

The presence of autoantibodies is the hallmark of systemic autoimmune diseases. During the past 30 years, intense clinical and basic research have dissected the clinical value of autoantibodies in many autoimmune diseases and offered new insights into a better understanding of the molecular and functional properties of the targeted autoantigens. Unraveling the immunologic mechanisms underlying the autoimmune tissue injury, provided useful conclusions on the generation of autoantibodies and the perpetuation of the autoimmune response. Primary Sjögren's syndrome (pSS) is characterized by the presence of autoantibodies binding on a vast array of organ and non-organ specific autoantigens. The most common autoantibodies are those targeting the Ro/La RNP complex, and they serve as disease markers, as they are included in the European-American Diagnostic Criteria for pSS. Other autoantibodies are associated with particular disease manifestations, such as anti-centromere antibodies with Raynaud's phenomenon, anti-carbonic anhydrase II with distal renal tubular acidosis, anti-mitochondrial antibodies with liver pathology, and cryoglobulins with the evolution to non-Hodgkin's lymphoma. Finally, autoantibodies against autoantigens such as alpha- and beta-fodrin, islet cell autoantigen, poly(ADP)ribose polymerase (PARP), NuMA, Golgins, and NOR-90 are found in a subpopulation of SS patients without disease specificity, and their utility remains to be elucidated. In this review, the molecular and clinical characteristics (divided according to their clinical utility) of the autoantigens and autoantibodies associated with pSS are discussed.