Epidemiologycomma; pathogenesiscomma; animal modelscomma; and treatment of Sjouml;gren's syndrome

摘要

Sjouml;gren's syndrome is characterized by dry eyes (xerophthalmia) and dry mouth (xerostomia). Although general agreement exists about the ocular features of Sjouml;gren's syndrome, significant controversy surrounds the classification criteria for defining the oral component. This has resulted in confusion in both the clinical and the research literature. The recent litigation involving silicone breast implants has forced clinicians to evaluate critically whether the condition of a particular patient fulfills specific diagnostic criteria for Sjouml;gren's syndrome. Research studies have focused on potential genetic and environmental factors in the pathogenesis of Sjouml;gren's syndrome. Studies of various ethnic populations have demonstrated an association with particular HLA-DR and -DQ alleles. However, the associated alleles are different for each ethnic group. No single environmental agent has been identified as a critical cofactor. Studies have concentrated on herpesviruses (Epstein-Barr virus and human herpesvirus type 6), hepatitis C virus, and retroviruses. Epstein-Barr virus isolated from patients has altered the ability to transform and lytically infect particular types of lymphocytes. Hepatitis C can lead to sicca symptoms, even in patients with relatively normal salivary gland biopsy findings. One report of Japanese patients indicated the presence of human T cell lymphotropic virus type I-liketaxgenes in the salivary biopsy specimens of a subset of patients and no gag, pol, or env sequences; this finding suggested a potential infection by a defective retrovirus. Studies on the pathogenesis have indicated that cytokines produced in the salivary gland are similar to T helper type 1 lymphocytes (interferon gamma). The induction of specific vascular cell adhesion molecule 1 and integrins may play a role in the trafficking of lymphocytes and their activation. The killing of epithelial cells in salivary and lacrimal glands may involve the induction of granzyme A. Therapeutic studies have been limited. A new type of artificial tear that uses polymers as a lubricating agent has been introduced, and studies have suggested a modest effect of pilocarpine in a subset of patients.