Objective. Disorganization of acinar cell apical microvilli and the presence of stromal collagen in the acinar lumen suggest that the labial salivary gland (LSG) barrier function is impaired in patients with Sjögren's syndrome. Tight junctions define cell polarity and regulate the paracellular flow of ions and water, crucial functions of acinar cells. This study was undertaken to evaluate the expression and localization of tight junction proteins in LSGs from patients with SS and to determine in vitro the effects of tumor necrosis factor ␣ (TNF␣) and interferon-␥ (IFN␥) on tight junction integrity of isolated acini from control subjects.Methods. Twenty-two patients and 15 controls were studied. The messenger RNA and protein levels of tight junction components (claudin-1, claudin-3, claudin-4, occludin, and ZO-1) were determined by semiquantitative reverse transcriptase-polymerase chain reaction and Western blotting. Tight junction protein localization was determined by immunohistochemistry. Tight junction ultrastructure was examined by transmission electron microscopy. Isolated acini from control subjects were treated with TNF␣ and IFN␥.Results. Significant differences in tight junction protein levels were detected in patients with SS. ZO-1 and occludin were strongly down-regulated, while claudin-1 and claudin-4 were overexpressed. Tight junction proteins localized exclusively to apical domains in acini and ducts of LSGs from controls. In SS patients, the ZO-1 and occludin the apical domain presence of decreased, while claudin-3 and claudin-4 was redistributed to the basolateral plasma membrane. Exposure of isolated control acini to TNF␣ and IFN␥ reproduced these alterations in vitro. Ultrastructural analysis associated tight junction disorganization with the presence of endocytic vesicles containing electron-dense material that may represent tight junction components.Conclusion. Our findings indicate that local cytokine production in LSGs from SS patients may contribute to the secretory gland dysfunction observed in SS patients by altering tight junction integrity of epithelial cells, thereby decreasing the quality and quantity of saliva.

Objective. Previous findings in labial salivary glands (LSGs) from patients with Sjögren's syndrome (SS) suggest that increased activity and expression of matrix metalloproteinase 9 (MMP-9) and MMP-3 trigger the destruction of acinar structures in these glands. Tissue inhibitors of matrix metalloproteinases (TIMPs) tightly control MMP activity, and TIMP expression is an important modulator of effects attributed to MMPs. This study was undertaken to investigate the correlation between the balance of MMPs/TIMPs in the LSGs of SS patients and the degree of inflammatory infiltration and acinar structure integrity.Methods. Three groups of SS patients classified according to focus score and residual tissue were studied. The expression of MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 was examined at the messenger RNA and protein levels. The ratio of MMP/TIMP expression (R value) was calculated. Focus score and acinar structure were evaluated by histologic analysis.Results. In SS patients the MMP-3/TIMP-1 ratio was higher than 1 and the MMP-9/TIMP-1 ratio was much higher than 1 whereas the MMP-2/TIMP-2 ratio nearly equaled 1, suggesting elevated proteolytic activity due mainly to MMP-9. R values were independent of the focus score of inflammatory cells, but correlated well with the dramatic changes observed in morphologic integrity of acini, as revealed mainly by the lack of nuclear polarity. Acinar changes were more evident when R values for both MMP-9/TIMP-1 and MMP-3/ TIMP-1 were higher.Conclusion. This study provides evidence that an altered balance between MMPs and their inhibitors is associated with acinar damage. Since salivary gland acinar cells express both MMPs and TIMPs, these cells may play an important role in extracellular matrix destruction and in the LSG pathophysiology in SS.Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that play a key role in tissue-remodeling events under both normal and pathologic conditions (1). Their expression is regulated by growth factors, cytokines, and hormones, as well as by interactions with extracellular matrix (ECM) proteins (1). Endogenous inhibitors, such as tissue inhibitors of matrix metalloproteinases (TIMPs), also exist to counterbalance MMP activity (2).To date, 4 TIMP family members have been described. TIMPs 1, 2, and 4 are secreted as soluble proteins, whereas TIMP-3 is associated with matrix components as an insoluble protein (3).

Reduced sulfation of muc5b is linked to xerostomia in patients with Sjögren syndrome Alliende, C.; Kwon, Y.-J.; Brito, M.; Molina, C.; Aguilera, S.; Pérez, P.; Leyton, L.; Quest, A.F.G.; Mandel, U.; Veerman, E.C.I.; Espinosa, M.; Clausen, H.; Leyton, C.; Romo, R.; González, S.

Objective. To investigate remodeling of the basal lamina of labial salivary glands (LSGs) from patients with Sjögren's syndrome (SS) by analyzing the expression of specific components that participate in its assembly and attachment to acinar and ductal cells.Methods. Two groups of SS patients with similar levels of remnant glandular tissue but with low and high levels of interacinar fibrosis, respectively, were studied. The expression of laminin ␣1, ␣4, and ␥2 chains and nidogens was examined at the messenger RNA (mRNA) and protein levels. Nidogens 1 and 2 were also studied in situ by immunohistochemistry.Results. Increases in the amount of mRNA and protein for both the processed and unprocessed laminin ␥2-chain were more pronounced in patients with low interacinar fibrosis. Increases in the protein levels of laminin ␣1 and ␣4 chains were observed in patients with low interacinar fibrosis, but not in those with high interacinar fibrosis. Nidogen mRNA and protein levels were similar in SS patients and controls. Interestingly, high levels of nidogen degradation were observed in patients with low interacinar fibrosis. Nidogens were readily detected by immunofluorescence in the basal lamina of the capillaries and stroma in SS patients, but were less apparent in the basal lamina of the acini and ducts.Conclusion. These results suggest that the basal lamina of LSGs from patients with SS is undergoing active remodeling, such that alterations are less evident in patients who have advanced morphologic signs of the disease (high interacinar fibrosis). Nidogen proteolysis might account for the disorganization of the basal lamina that is typically observed in LSGs from SS patients, assuming that cleavage impairs their ability to crosslink type IV collagen and laminin networks.Sjögren's syndrome (SS) is a chronic disorder that leads to insufficient production of saliva and tears (1,2). Labial salivary glands (LSGs) from patients with SS show dramatic changes in the basal lamina of the acini and ducts, including loss of individual components and structural disorganization, as detected by morphologic analysis. These events favor invasion of the acini and ducts by inflammatory cells that trigger cytotoxic responses (3). However, acinar cell death is also promoted by detachment of the cells from their extracellular matrix (ECM), a process known as anoikis (4). Importantly, the latter process does not require the presence of mononuclear cells. Instead, matrix metalloproteinases (MMPs) secreted by the acinar and ductal cells themselves have been implicated; in particular, imbalanced ratios of MMP-9 to tissue inhibitor of meMs Pérez and Ms Brito