Sjögren's syndrome: why autoimmune epithelitis?

The expression 'autoimmune epithelitis' has been proposed as an alternative for Sjögren's syndrome (SS) based on data pointing out the central role of the epithelial cell in the pathogenesis of the syndrome. Clinically, apart from exocrine glands that are the main target, the epithelial component of the other organs such as kidneys, liver, lungs or thyroid is commonly affected resulting in various extraglandular manifestations. On the other hand, at the molecular and cellular level, the epithelial cell plays a major role in the initiation and perpetuation of the autoimmune lesion. Mechanisms such as antigen presentation, apoptosis, chemokine production or germinal center formation lie in the center of SS pathogenesis and the epithelial cell has a very important role. Herein, we present both aspects, review the data that support the proposed terminology and finally, suggest a unifying theory for the pathogenesis of SS.