Differential expression of matrix metalloproteinases in labial salivary glands of patients with primary Sjögren's syndrome

OBJECTIVE: To determine the enzymatic activity and cellular localization of matrix metalloproteinases (MMPs) 2, 3, and 9 in labial salivary glands from patients with different degrees of severity of primary Sjogren's syndrome (primary SS). METHODS: Gelatinase activity was determined by zymography and quantified by densitometry. The specificity of MMPs was determined using protease inhibitors and chelators, as well as activators of the latent forms of these enzymes. The cellular localization of MMPs was carried out using monoclonal antibodies that recognize their latent and active forms. RESULTS: Labial glands from control subjects and patients showed gelatinase activity for MMP-2 and MMP-9. Activation studies revealed that both enzymes were predominantly present in their latent forms. The highest levels of MMP-9 activity were detected in patients with severe, active, primary SS (except for patients with severe clinical symptoms for extended periods) and correlated with structural and functional glandular changes. MMP-2 activity was almost the same in patients and controls. MMPs were detected by immunolocalization only in acinar and ductal cells and were homogeneously distributed throughout patients' glands. MMP-2 and MMP-9 expression paralleled their gelatinase activity. MMP-3, detectable only with immunologic methods, was absent in control subjects but abundantly expressed in patients. Importantly, MMP protein levels in acinar and ductal cells were independent of either the presence or the proximity of mononuclear infiltrate cells. CONCLUSION: MMP-3 and MMP-9 expression, as well as MMP-9 catalytic activity, were increased in tissue samples from SS patients in a manner that correlated with the severity of the disease. Most important, increased MMP activity stemmed from exocrine epithelial cells and was not due to infiltrating lymphocytes. Thus, changes in salivary glands as a consequence of proteolysis may lead to severe glandular destruction.     

BAFF-modulated repopulation of B lymphocytes in the blood and salivary glands of rituximab-treated patients with Sjögren's syndrome

OBJECTIVE: Treatment with rituximab depletes B cells from the peripheral blood (PB) and salivary glands (SGs) of patients with primary Sj?gren's syndrome (SS). The purpose of this study was to track the repopulation of B cell subsets in PB as well as their subsequent homing into SGs in patients with primary SS treated with rituximab. METHODS: A series of 4-color flow cytometry experiments delineated B cell subsets in 15 patients with primary SS. All were tested on days 8 and 15 of treatment. Nine of the patients were followed up monthly for 10 months, and the remaining 6 patients were followed up monthly for 24 months. Enzyme-linked immunosorbent assays were developed to measure serum levels of BAFF and rituximab. SGs were biopsied at the start of the study and 4 months after treatment in 15 patients, 12 months after treatment in 3 patients, and 24 months after treatment in 2 patients. RESULTS: Baseline serum levels of BAFF correlated inversely (r = -0.92, P < 5 x 10(-4)) with the duration of B cell depletion: the higher the BAFF levels, the shorter the duration of B cell depletion. Four B cell subsets repopulated the PB: plasmablasts (CD19+, CD5-,IgD-,CD38++), transitional type 1 (T1) B cells (CD19+,CD5+,IgD+,CD38++), mature Bm2 cells (CD19+,CD5+/-,IgD+,CD38+/-), and memory B cells (CD19+,CD5-,IgD-,CD38-). Increased numbers of Bm2 cells and decreased memory B cells reappeared with time. Sequential SG biopsies revealed that B cells were absent in these glands for 12 months: they were detected 24 months after rituximab treatment. Memory and T1 B cells were the first B cells identified locally. CONCLUSION: The timing of B cell repopulation is modulated by BAFF and is followed by reconstitution of the preexisting abnormalities.     

Overexpression of phosphorylated STAT-1alpha in the labial salivary glands of patients with Sjögren's syndrome

OBJECTIVE: To clarify the molecular mechanisms of Sj?gren's syndrome (SS), we analyzed the functional role of the STAT-1 gene, one of the interferon-gamma (IFNgamma)-inducible genes, in labial salivary glands (LSGs) from SS patients. METHODS: The expression of STAT-1 messenger RNA (mRNA) was examined by real-time polymerase chain reaction (PCR) analysis, and the phosphorylation of STAT-1 protein (Tyr(701) and Ser(727) pSTAT-1) was investigated by Western blot and immunohistochemical analyses. The expression of IFNgamma-inducible 10-kd protein (IP-10), IFN regulatory factor 1 (IRF-1), and Fas was also examined by real-time PCR and immunohistochemical analyses. RESULTS: STAT-1alpha and STAT-1beta mRNA were highly expressed in LSGs from SS patients. The level of STAT-1alpha protein in SS LSGs was higher than that in 3 control LSGs, whereas STAT-1beta protein was not clearly detected by Western blot analysis. Moreover, Tyr(701) and Ser(727) pSTAT-1alpha proteins were specifically detected in SS LSGs. Immunohistochemical analysis showed localization of Tyr(701) pSTAT-1 in infiltrating lymphocytes and the adjacent ductal epithelium from SS patients. Ser(727) pSTAT-1 was localized only in the ductal epithelium of SS LSGs. The STAT-1-inducible genes IP-10 and IRF-1 and the Fas genes were highly expressed in SS LSGs and were colocalized with Ser(727) pSTAT-1-positive, but not Tyr(701) pSTAT-1-positive, cells. CONCLUSION: We found evidence of the up-regulation of STAT-1alpha mRNA and protein in LSGs from SS patients, as well as the presence of pSTAT-1alpha in ductal epithelium from SS patients. Our findings suggest that STAT-1alpha, especially Ser(727) pSTAT-1, may function as a key molecule in the pathogenesis of SS.     

Increased salivary interleukin-6 levels in patients with primary Sjögren's syndrome

This study's purpose was to evaluate salivary interleukin-6 (IL-6) levels in patients with primary Sjögren's syndrome (SS). Salivary and serum IL-6 concentrations were evaluated by ELISA in 36 patients with SS and compared with 19 patients complaining of dry mouth and with normal controls. Salivary IL-6 levels were significantly elevated (P<0.01) in the 36 patients with SS as compared to the 19 patients with dry mouth (200.5±43.6 and 12.6±6.8 pg/ml, respectively). No significant differences were noted in the serum IL-6 levels between these two groups (105.8±17.1 and 84.8±17.1 pg/ml, respectively). Both salivary and serum IL-6 levels in the normal controls were below the level of detection of the assay. Positive correlation (r = 0.8613, P<0.0001) was found between salivary IL-6 levels and the focus score of labial biopsies in SS patients. Elevated salivary IL-6 levels appear to be a consequence of local production and may reflect the component of salivary gland inflammation in SS.     

Sialic acid residues in the labial salivary glands from Sjögren's syndrome patients

OBJECTIVE: To investigate the composition and expression of sialic acid in the labial salivary glands (LSG) in Sj?gren's syndrome (SS). METHODS: LSG of 19 patients with primary SS (n = 11) or secondary SS (n = 8) were studied. Specimens from 7 healthy women served as controls. Computer-assisted microscopy was employed to quantitatively determine the percentage of positive structures, the staining intensity and the heterogeneity for the 4 biotinylated plant lectins Tritricum vulgaris L. (WGA), Maackia amurensis (MAA), Sambucus nigra (SNA) and Canavalia ensiformis L. (Con A). RESULTS: In the acini there was a significant decrease in the staining heterogeneity of WGA in SS compared to controls; the same was observed with respect to MAA staining in the connective tissue and extralobular ducts. In the intralobular ducts, primary SS differed from normal and secondary SS mainly in terms of a decrease in the percentage of positively labeled MAA tissue. In addition, Con A stained acinar cells were significantly more numerous in secondary SS compared with primary SS. CONCLUSION: Differences in the degree of glycoconjugate sialylation were found in SS labial salivary glands, and may play a role in the disease process.     

Diminished peripheral blood memory B cells and accumulation of memory B cells in the salivary glands of patients with Sjögren's syndrome

OBJECTIVE: To delineate the mechanism of the abnormalities in B cell biology found in patients with primary Sj?gren's syndrome (SS). METHODS: The distribution of peripheral B cell subpopulations in 21 patients with primary SS was analyzed by immunofluorescence labeling and flow cytometry. Immunoglobulin rearrangements were analyzed in single B cells isolated from the peripheral blood and parotid glands by fluorescence-activated cell sorting. RESULTS: A significant reduction in the number of peripheral CD27+ memory B cells was found in SS patients, including a significantly reduced number of CD27+/IgD+/IgM+/CD5+ memory B cells. Remarkably, SS patients with secondary lymphoma uniquely exhibited an increase in CD27-expressing peripheral B cells, including CD27(high) plasmablasts. Molecular analysis for mutated Ig gene rearrangements confirmed that CD27 expression distinguished naive and memory cells in SS. In contrast to the peripheral blood, the majority of parotid B cells from 1 patient examined exhibited both the mutational status and phenotype of memory B cells. Accordingly, the mutational frequencies of V(H) rearrangements were significantly greater in parotid B cells than in peripheral blood B cells, whereas the V(H) gene repertoire appeared to be very similar between the compartments. CONCLUSION: These data indicate that there is an accumulation/retention of memory B cells in the inflamed salivary glands of SS patients. It is possible that preferential accumulation of CD27+ memory B cells in the inflamed parotid gland explains their reduction in the peripheral blood.     

B lymphocytes in Sjögren's syndrome

INTRODUCTION: Sj?gren's syndrome (SS) is an autoimmune epithelitis hallmarked by a disruption of epithelial cells, the subsequent lymphocytic infiltration of lachrymal and salivary glands (SGs), and their ensuing dryness. One may posit that SS is triggered by viruses, and/or modulated by sex steroid hormones, and there is indeed a consensus that its aetiology is multifactorial, with genetic factors interacting with environmental agents. CURRENT KNOWLEDGE AND KEY POINTS: T-cells have long occupied central stage of the debate on the type of lymphocytes involved in the pathogenesis of SS. The relevance of B cells has, however, been emphasized over the past five years and new insights into their functions revealed. Furthermore, increased levels of the B-cell activating factor (BAFF) may be responsible for quantitative and qualitative anomalies of B-cells found in SS such as emergence of self reactive B-cells. This review reports compelling evidence that B-cells are involved in the pathophysiology of SS. PROSPECTS: Since SS may thus be conceived as a model for B-cell-induced autoimmunity, it is no surprise that B-cell ablative-treatment has proven to be relatively effective in SS.     

Association of plasmacytoid dendritic cells with B cell infiltration in minor salivary glands in patients with Sjögren's syndrome

Objectives: Sjogren’s syndrome (SS) is an autoimmune disease with features of both over-production of specific autoantibodies and organ-specific disorders, mainly sialadenitis and dacryoadenitis. However, little is known about the factors that contribute to lymphocytic infiltration of SS.

Methods: Minor salivary gland (MSG) tissue was obtained from 83 patients with primary SS (pSS) and 95 patients with secondary SS and examined pathologically, and correlation between infiltrated immune cells and histological features was evaluated.

Results: Plasmacytoid dendritic cells (pDCs) were increased in MSG of SS compared to Sicca syndrome. The density of pDCs was characteristically correlated with the accumulation of CXCL13⁺CD68⁺ macrophages and CXCR5⁺CD19⁺ B in the MSG of pSS. In vitro analysis indicated that Type I interferon (IFN) enhanced CXCL13 production by macrophages. Type I IFN was mainly expressed in pDCs and its expression was correlated with the accumulation of CXCL13⁺ macrophages in the MSG of pSS.

Conclusions: Our histological findings suggest the possible mechanism of type I IFN-CXCL13 axis during the pathological processes of acute/chronic salivary inflammation in SS; local production of type I IFN by pDCs, induction of CXCL13 production in macrophages by type I IFN, induction of accumulation of CXCR5⁺CD19⁺ B cells by CXCL13 in the MSG.     

An immunohistochemical study of immunological phenomena in minor salivary glands in patients with Sjögren's syndrome

Using different monoclonal antibodies, we performed an immunofluorescent technique on labial salivary glands in order to investigate the immunological phenomena involved in Sjögren's syndrome (SS). An aberrant expression of HLA-DR molecules was detected on cytoplasm of epithelial labial salivary cells in 9 out of 19 (47%) patients, with SS. No such expression was found in 8 patients without SS or in 3 normal controls. HLA-DQ molecules were demonstrated also in two out of ten SS patients without HLA-DR. A lymphocytic infiltration was not correlated with the expression of class II molecules. T cells bearing receptors were not detected. The intracellular adhesion molecules (ICAM-1) and lymphocyte function associated antigen-1 (LFA-1) were not found on epithelial glandular salivary cells of patients and controls. In conclusion, these data suggested that the absence of ICAM-1 and LFA-1 in salivary cells and the absence of infiltrating T cells bearing receptors exclude their immunopathogenetic role in SS; moreover, these data demonstrated that the aberrant expression of HLA class II molecules on epithelial salivary cells of patients with SS is not a phenomenon correlated with the lymphocytic infiltration.     

Platelet involvement in salivary gland inflammation in patients with primary Sjögren's syndrome

Summary Seventeen consecutive patients under evaluation for Sjögren's syndrome (SS) had a lower lip salivary gland biopsy performed. Using a monoclonal mouse immunoglobulin against human platelet glycoprotein Ib in an indirect immunoperoxidase technique, it was found that platelets accumulate intravascularly in the inflamed salivary glandular areas. Platelets were demonstrated in the interstitial tissue of inflammed salivary glands from two patients. Saliva from 17 consecutive patients with previously well-established primary SS and 11 healthy controls, and blood from 11 of the patients and all controls were then examined for platelets and the platelet-specific release product -thromboglobulin (-TG). Platelets were not demonstrated in saliva from patients or controls. -TG was detected in saliva from five patients (11–150 ng/ml), but in none of the controls. There were no correlations between saliva -TG levels and saliva secretion rates or plasma -TG levels. We conclude that platelet release of -TG into saliva in patients with primary SS most likely is a result of immunoinflammatory reactions in salivary glands. Measurement of -TG in saliva may be of value in the estimation of disease activity.     

Is periodontal disease mediated by salivary BAFF in Sjögren's syndrome?

OBJECTIVE: To correlate the periodontal status of 15 patients with primary Sj?gren's syndrome (SS) with their salivary levels of BAFF. METHODS: The periodontal status of 15 patients who fulfilled the criteria for primary SS was compared with that of 15 controls with xerostomia who did not fulfill the criteria for primary SS but had similar symptoms of dry mouth. The level of BAFF was measured in paired samples of saliva and serum using in-house enzyme-linked immunosorbent assays. Periodontitis was assessed by the plaque index, the modified gingival index, the papillary bleeding index, and the periodontal pocket depth. RESULTS: Notwithstanding the better oral hygiene practices of the patients with primary SS compared with those of the xerostomia controls and the subsequent reduction of their plaque index scores, complications of periodontitis, such as bleeding, gingival hypertrophy, and periodontal pockets, were not improved. This failure to ameliorate the complications of periodontitis in patients with primary SS was associated with high levels of BAFF in their saliva compared with the levels in xerostomia controls (7.4 +/- 2.1 versus 1.0 +/- 0.4 ng/ml [P < 0.002]). The levels of BAFF in saliva did not correlate with the levels in sera but did correlate with the periodontal pocket depth (P < 0.002). CONCLUSION: These findings are similar to the bone resorption observed in patients with rheumatoid arthritis. They suggest that the known effect of B cells in periodontitis would be partly mediated by salivary BAFF in patients with primary SS.