Explore The Role Of Baff\baff-r In The Pathogenesis Of Primary Sjogren's Syndrome

【Objective】Sjogren's syndrome (SS) is a chronic autoimmune disordercharacterized by lymphocytic infiltration and destruction of the exocrineglands, especially salivary gland and caruncula innominata, resulting in oraland ocular dryness. Though the mechanism underlying is unclear, B cellshyperactivity is the hallmark of the syndrome. B-cell activating factorfrom TNF family (BAFF), a newly found cytokine factor, is found take acritic role of in the proliferation and activation of B cells, and even in theproduction of immunoglobulin of B cells [1]. In addition, BAFF productionis also found overexpressed in patients with a few autoimmune diseasesincluding rheumatoid arthritis (RA) and systemic lupus erythematosus(SLE) [2-6]. Moreover, Belimumab, an anti-Blys human monoclonalantibody for potential treatment SLE has been shown its effectiveness inthe phase II trial [7].As a member of autoimmune disease, SS has also been found that the overexpession of BAFF in its salivary gland, parotid gland and sera.Some researcher has been reported that the lever of IgG and ESR areassociated with BAFF production in SS patients[8]. All of these publishedreports further suggest that BAFF play a crucial role in the developmentof SS. Recently, BAFF has been proved effectively in the assessment ofdiagnosis and prognosis of diffuse large B-cell lymphoma [9], but few beenreported in the diagnose of rheumatic diseases, esepecially in SS.Performance of minor salivary gland biopsy has been one of thecommonly used but important methods in the diagnosis of SS than that ofparotid gland. Thus, it is more necessary to detect the expression of BAFFin salivary gland than in parotid gland. In the present study, we identifythe expression of BAFF in the serum and BAFF Receptor (BAFF-R) bothin serum and on peripheral B cells/labial salivary glands from patientswith SS (including pSS and SS overlapping other connective diseases),thereby to explore the important role of BAFF in the pathogenesis of pSSand further to assess the diagnostic value of BAFF-R for SS.【Methods】1. 15 patients with pSS and 15 patients with SS overlappingRA/SLE were recruited in study. 15 healthy donors served as controls.2. The expression of BAFF-R was detected on labial salivary glandsby immunohistochemistry.3. The expression of BAFF-R was detected in CD19+ B cells inperipheral blood by flow cytometry.4. The level of soluble BAFF in serum was detected by ELISA. 【Results】1. BAFF-R was strongly stained on labial salivary glands from 13/15pSS-paients ( 86.7%), while weakly stained on that of the controls.AS for 15 SS overlapping RA/SLE patients, 12/13(75.0%) labialsalivary positively expressed BAFF-R.2. BAFF-R was also expressed significantly higher in CD19+ B cellsfrom pSS-patients and SS overlapping RA/SLE patients than that ofcontrols. (P<0.001)3. Soluble BAFF was highly detected in sera of pSS-patients and SSoverlapping RA/SLE patients than that of controls.【Conclusion】Our study further suggested that BAFF may play an important role inthe pathogenesis of pSS by activating self-reactive B cells, and we alsoprovide some primary evidence for the diagnosis of pSS by detectingBAFF-R on labial salivary glands.