Herpes group viruses in the clinicopathological course of sjögren's syndrome

Sjögren?s syndrome is a chronic systemic autoimmune disease characterized by lymphocytic infiltration of the exocrine glands as well as involvement of many other extraglandular tissues. The disease mainly presents itself with symptoms of dry eye and dry mouth due to involvement of the salivary and lacrimal glands. Although it is one of the most common autoimmune diseases seen in the population, due to its complicated pathobiololgy and the differences between the classification criteria, the diagnosis is difficult to make. The etiology of Sjögren?s syndrome is still unknown but genetic predisposition together with the environmental factors are the most investigated factors. Among the environmental factors viruses especially the Epstein Barr virus and the Cytomegalovirus have long been investigated.The studies up to date have announced conflicting results concerning the relationship between these two viruses and the disease. In our study, 87 patients that admitted to our rheumatology clinic and have been followed up with the suspicion of Sjögren?s syndrome were involved. We performed minor salivary gland biopsy to every patient to confirm the diagnosis and while taking the biopsy, a specimen was separated for the real time polymerase chain reaction study for the detection of EBV and CMV DNA. Then, we classified the patients according to both the European and the revised American European Consensus Group criteria as having Sjögren?s syndrome or not. We compared the results of the molecular study with the clinical and serological findings of the patients. We found that in terms of the presence of EBV DNA in the salivary glands, there was no statistically significant difference between the patients having Sjögren?s syndrome or not according to either criteria. But interestingly among the patients classified as having Sjögren?s syndrome according to European preliminary criteria, the association between the positive biyopsies that had focus score ?1 and presence of EBV DNA in the salivary glands was found to be statistically significant (p=0,018). The CMV DNA was detected in only 3 of the patients involved and they were all in the non-Sjögren group.Altogether these data suggest that EBV may act as a cofactor in the pathogenesis of Sjögren?s syndrome increasing the autoimmune response in the genetically susceptible individuals rather than a trigger itself. But according to our results we have no evidence suggesting any relationship between CMV infection and Sjögren?s syndrome.