Association between Increased Bcl-2, Fas and FasL Levels and Inflammation Extent in Labial Salivary Glands During Primary Sjögren's Syndrome

Background: Primary Sjögren Syndrome (pSS) is a chronic autoimmune disease characterized by epithelial atrophy, mononuclear infiltration in exocrine glands resulting in the defective function of these glands. In pSS, atrophy of the epithelium is caused by an increased amount of apoptosis. Objective: The main aim of this study is to investigate the role of the apoptosis-related factors by studying Bcl-2, Fas and FasL expression in relation to the extent of inflammation as well as the effect of therapy on the expression of these mediators. Methods: In pSS patients (n=62) documented for their serological and clinical features, Fas, FasL and Bcl-2 plasma levels were assessed using enzyme-linked immunosorbent assays. In the same context, we investigated their expression by immunohistochemistry analysis in the labial salivary glands samples in association with the extent of inflammation. Results: Interestingly, our results indicated that in pSS patients, the plasmatic Bcl-2, Fas and FasL levels, which appeared to be associated with the severity of inflammation and were significantly elevated in comparison to the healthy controls. Moreover, a significant decrease in all these factors was observed in patients after combined corticosteroids-hydroxychloroquine therapy. Importantly, we report a strong positive correlation between Bcl-2 and NO levels. The immunohistochemical staining reveals a strong Bcl-2 expression in infiltrating mononuclear cells and a total absence in the acinar cells. The Bcl-2 level varies according to the severity of pathology. However, the expression of Fas and FasL was less important and predominantly localized in infiltrating mononuclear cells. Conclusion: Our current study highlights the involvement of Bcl-2, Fas and FasL in pSS glands injury. These factors may act as useful predictor markers of a clinical course in pSS, suggesting a novel approach in the pSS patients monitoring.