Ewert Patricia, Aguilera Sergio, Alliende Cecilia, Kwon Yoon-Jeoung, Albornoz Amelina, Molina Claudio, Urzúa Ulises, Quest Andrew F G, Olea Nancy, Pérez Paola, Castro Isabel, Barrera María-José, Romo Rafael, Hermoso Marcela, Leyton Cecilia, González María-Julieta
University of Chile, Santiago, Chile.
Arthritis Rheum. 2010 May;62(5):1280-9. doi: 10.1002/art.27362.
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 alpha (TNFalpha) and interferon-gamma (IFNgamma) on tight junction integrity of isolated acini from control subjects.
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 TNFalpha and IFNgamma.
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 TNFalpha and IFNgamma 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.
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.
腺泡细胞顶端微绒毛紊乱以及腺泡腔内存在基质胶原蛋白表明，干燥综合征患者的唇唾液腺（LSG）屏障功能受损。紧密连接决定细胞极性，并调节离子和水的细胞旁流动，这是腺泡细胞的关键功能。本研究旨在评估干燥综合征患者LSG中紧密连接蛋白的表达和定位，并在体外确定肿瘤坏死因子α（TNFα）和干扰素γ（IFNγ）对来自对照受试者的分离腺泡紧密连接完整性的影响。
对22例患者和15名对照进行研究。通过半定量逆转录聚合酶链反应和蛋白质印迹法测定紧密连接成分（闭合蛋白-1、闭合蛋白-3、闭合蛋白-4、闭合蛋白和ZO-1）的信使核糖核酸和蛋白质水平。通过免疫组织化学确定紧密连接蛋白的定位。通过透射电子显微镜检查紧密连接超微结构。用TNFα和IFNγ处理来自对照受试者的分离腺泡。
在干燥综合征患者中检测到紧密连接蛋白水平存在显著差异。ZO-1和闭合蛋白强烈下调，而闭合蛋白-1和闭合蛋白-4过表达。紧密连接蛋白仅定位于对照LSG的腺泡和导管的顶端结构域。在干燥综合征患者中，顶端结构域中ZO-1和闭合蛋白的存在减少，而闭合蛋白-3和闭合蛋白-4重新分布到基底外侧质膜。将分离的对照腺泡暴露于TNFα和IFNγ在体外再现了这些改变。超微结构分析将紧密连接紊乱与含有可能代表紧密连接成分的电子致密物质的内吞小泡的存在相关联。
我们的研究结果表明，干燥综合征患者LSG中的局部细胞因子产生可能通过改变上皮细胞的紧密连接完整性，导致干燥综合征患者观察到的分泌腺功能障碍，从而降低唾液的质量和数量。
