The Pathogenic Role Of Transcription Factor Bcl-6/Blimp-1in Primary Sjogren’s Syndrome

Bcl-6(B cell lymphoma6) is belonging to the anti-apoptotic oncogenewhich expresse on T and B lymphocyte. The expression of Bcl-6is enhancedin T and B lymphocyte after stimulated by antigens and cytokines. It canaccelerate the T and B cell undergoing mitosis process, migrating to thecentral follicular region of lymphocytes and formating germinal center (GC).Bcl-6is an important signal of germinal center formation. Lack of theexpression of Bcl-6will lead to differentiation stagnation of helper Tlymphocyte and B lymphocyte and be unable to form a germinal center.Blimp-1,(B lymphocyte induced maturation protein-1) and Bcl-6is a pair ofmutually antagonistic transcription factors. The expression of physiologicallevels of Blimp-1can inhibit CD4+T cells differentiate into follicular helper T（Tfh）lymphocytes cells.At present, it is generally believed that in the process of the developmentof primary Sjogren’s syndrome, excessive activation of T and B cells involvedin focal lymphocytic (germinal center) formation of the salivary glands andthen lead to glands function damage. The overactivation of T and B cells willproduce many autoantibodies and cause systemic inflammatory autoimmunediseases. Because of Bcl-6induce and maintain forming germinal center, itmaybe participate in the immune disorder mechanism of primary Sjogren’ssyndrome. In this research paper, we will detect the expression level ofBcl-6/Blimp-1proteins in salivary glands of patients with primary Sjogren’ssyndrome intend to explain its clinical significance.Objective: To detect lymphocytes infiltrating degree of labial salivarygland in primary Sjogren’s syndrome（PSS）and to detect the expression ofBcl-6/Blimp-1prorein on T、B cell. At the same time, to research therelationship between Bcl-6/Blimp-1protein levels and lymphocytes infiltrating degree, and involved organs and laboratory indexes.Furtheranalysis pathogenic effect of Bcl-6/Blimp-1prorein in PSS.And to discussliological effect of Bcl-6/Blimp-1prorein in occurring and developing of PSS.Methods: We chose30cases of primary Sjogren’s syndrome patients asdisease group in the department of rheumatology of the Second Hospital ofHebei Medical University during March2012to December2013. including2cases with renal tubular acidosis,8cases with blood system damage(including leucopenia、thrombocytopenia、complete blood reduced),2caseswith peripheral neuropathy,5cases with pulmonary interstitial fibrosis,13cases without organ system damage. Before labial salivary gland biopsy, all ofthe patients were untreated by any hormors and immunoinhibitors. Anotherwe chose11cases patients with mucous cyst, lower lip trauma or othernon-autoimmune disease in oral surgery as control group. All the biopsiessample were placed into10%formaldehyde for24hours, embed in paraffin,HE staining and sectioned for4μm thickness, and stained with hematoxylin.To detect the expression of Bcl-6/Blimp-1protein by usingimmunohistochemical technology. To observe the expression of differences ofBcl-6/Blimp-1protein between the any two groups, positioning, and itsrelationship between the infiltration of lymphocytes, plasma cells and GCformation. To count the mean number of positive cells of five highermagnification field in tissue section. according:0score, Positive cells <1%;1score, Positive cells1%-25%;2score, positive cells26%-50%;3score,Positive cells51%-75%,4score Positive cells＞75%. Positive single isdivided into three categories according to the degree of staining: weakstaining intensity (+): light yellow or individual cells are yellow tobrownish-yellow, denoted1; strong staining intensity (+++): yellow to brownstaining, denoted3; Moderate-intensity staining: between weakly positive andstrongly positive, denoted2；Negative is not stained. Last comprehensivescore equal to the score that staining intensity score×the percentage score ofpositive cells. Comprehensive score≥1is positive expression,<1comparedwith negative expression. According to Chisholm pathological classification standard, all samples are divided into four degrees: Ⅰ~Ⅳ ranks. Each ofthem is representative different lymphocytes infiltrating degree in salivarygland tissues separately: seldom-number lymphocytes infiltration, moderatenumber lymphocytes infiltration，one focal lymphocytes in the tissues, multifocal lymphocytes in the tissues. Statistical analyses are performed by usingSPSS13.0（SPSS Company, Chicago，Illinois，USA）.Between the two groupsare compared using two independent samples rank sum test. Bcl-6/Blimp-1protain expression in multiple independent sample is used to multipleindependent samples rank sum test, the correlation between the two level datawere analyzed using spearman correlation coefficient.Statistical descriptionuses medican、interquartile up、interquartile low.The testing level was α=0.05(two tailes), P <0.05was considered statistically significant.Results:1Under light microscope, tissues from the control group had unform size,conduit arranged in neat rows, no expansion, there is no or a small amount ofinflammatory cell infiltration in stromal; In disease group, acinar had differentsizes, glandular atrophy partly, especially around the catheter, there had one ormore focal lymphocytic infiltration in stromal.2In control group，the expression level of Bcl-6protain betweendisease and control groups are3.0(2.0，4.0)、0.0（0.0,1.0）point，respectively.There is statistical significantly difference (P <0.001); In disease group, Bcl-6expressed highly in focal infiltration lymphocytes around labial grand duct.Positive cells accidentally detect in acinar cells. The expression of Bcl-6iscorrelated positively to the number of lymphocyte focus (rs=0.644, P<0.001).3The expression level of Blimp-1protain between disease and controlgroups are3.0（2.0,4.0）、1.0（0.0,1.0）point，respectively. There is statisticalsignificantly difference (P <0.001); In disease group, Blimp-1protainexpressed highly in focal infiltration lymphocytes around labial grand duct.Positive cells accidentally detect in acinar cells. The expression of Blimp-1protain is correlated positively to the number of lymphocyte focus (rs=0.637， p<0.001).4In disease group, the comparison of the clinical complications: renaltubular acidosis, blood system damage, peripheral neuropathy, pulmonaryinterstitial fibrosis and no organ system damage in patients with pSS, theBcl-6protein expression level is3.5（1.0*,6.0*）、3.0（2.0,3.0）、4.5（3.0*,6.0*）、4.0（2.5,4.0）、3.0（2.5,4.0）point，respectively. There is nostatistically significant difference after statistics analysis. Five groups ofBlimp-1protein expression level is respectively2.5（1.0*,4.0*）、3.0（2.0,4.0）、3.0（2.0*,4.0*）、4.0（3.0,6.0）、2.0（2.0,4.0）point，after statistics analysis,there is also no statistically significant difference.5Comparison of laboratory indexes: In disease group, the expressionlevel of Bcl-6protain in immunoglobulin-high(IgG) group and immunoglo-bulin-normal (IgG) group are3.0（3.0,4.0）、3.0（2.0,3.0）point， respectively.There are no statistically significance between these two group. Theexpression level of Blimp-1protain in immunoglobulin-high(IgG) group andimmunoglobulin-normal (IgG) group are4.0（2.0,4.0）、2.0（2.0,4.0）point，respectively, There are no statistically significance between these two group.In increased β2microglobulin (β2MG) group and normal group, the Bcl-6/Blimp-1protain expression levels are no statistically significant bystatistical analysis.6Correlation analysis showed that the expression of Bcl-6proteinexpression level in lymphocytic focal of disease group is significant positivelyrelated to Blimp-1protein（rs0.566, P0.001）.Conclusions:The expression high levels of Bcl-6/Blimp-1protain inlabial gland germinal center of patients with primary Sjogren’s syndrome.They are related to lymphocyte infiltration degree in labial gland tissues. Twotranscription factor protein maybe involved in the pathogenesis of primarySjogren’s syndrome, in words Tfh maybe play a critical role in the damagement of labial salivary glands in patients with PSS.