Autoimmune epitheliitis: Sjögren's syndrome

Abstract

Sjögren's syndrome (SS), an autoimmune exocrinopathy, is a common, chronic disease of females. Clinical studies of kidney involvement in SS patients have shown that the predominant lesion is interstitial nephritis which produces tubular dysfunction. Studies on lung involvement have previously indicated that one fourth of SS patients suffer from subclinical interstitial lung disease. Re-evaluation, however, of the pulmonary disease using functional, radiologic and histopathologic studies showed that the lesion starts peribronchially. Finally, evaluation of liver disease in SS patients revealed that this consists of a pericholangeal round-cell infiltrate resembling the early lesion of primary biliary cirrhosis. These clinical studies suggest that the systemic manifestations of SS are probably due to the attraction of lymphocytes by different epithelial tissues. Studies of the epithelial cells of minor salivary glands from SS patients have shown that these inappropriately and selectively express HLA class II molecules and the proto-oncogene c-myc. Evaluation of cytokines in the minor salivary glands from these patients by in situ hybridization revealed that the proinflammatory cytokines IL-1 and IL-6 are also produced by the epithelial cells. Finally, proviral DNA has been shown to be incorporated in the DNA of epithelial cells. On the basis of these clinical and laboratory observations, we would like to suggest that the target tissue involved in the autoimmune histopathologic lesions of SS is the epithelium, and therefore we propose the term "Autoimmune Epitheliitis" instead of "Sjögren's syndrome" for this disease.