幹燥綜合征為自身免疫性疾病，因存在淚腺和唾液腺功能障礙，可表現為口幹、眼幹。原發性幹燥綜合征患者唾液減少。因水的運動參與唾液分泌，水通道蛋白的表達、定位和功能已在唾液腺中廣泛研究。迄今為止，AQP4是否存在於人類的唾液腺，目前仍然有爭議。我們通過免疫組化、高分辨率顯微鏡和圖像定量分析、Western blot和RT-PCR，鑒定正常對照組及原發性幹燥綜合征患者唾液腺活檢中是否存在AQP4基因，同時明確AQP4蛋白分布。通過免疫組化分析，我們發現幹燥綜合征及正常對照組中，AQP4局限於腺泡基底部、閏管和紋狀管側麵和頂部。最引人注目的結果為觀察到AQP4定位於環繞腺泡小葉和閏管的肌上皮細胞(MEC)，且幹燥綜合征MEC中發現AQP4下調免疫反應。我們的研究結果提示，肌上皮細胞膜的跨膜水流能力在幹燥綜合征中可能改變。提示AQP4可能成為治療口幹的有前途的新治療藥物。

附原文

Abstract：A decreased saliva production occurs in primary Sjögren's syndrome(pSS), an autoimmune disease characterized by oral and ocular dryness due to dysfunction of the lacrimal and salivary glands (SGs). Since water movement is involved in saliva secretion, the expression, localization, and function of the water channels aquaporins (AQPs) have been extensively studied in SGs. To date, the presence of AQP4 remains controversial and ambiguous in human SGs. We investigated by immunohistochemistry, high-resolution confocal microscopy and quantitative image analysis, Western blot and real-time RT-PCR, the presence of the AQP4 gene, and the distribution of AQP4 protein in healthy controls and pSS SG biopsies. Through the immunohistochemical analysis, we demonstrated that AQP4 presence is confined to the basal region of acini, to the lateral and apical membrane of intercalated and striated ducts in both control and pSS glands. The most striking observation was the discovery of AQP4 localization in myoepithelial cells (MECs) that surround acini lobules and intercalated ducts, and the demonstration of AQP4-downregulated immunoreactivity in pSS MECs. Our studies suggest that the capacity for water flow across the membrane of MECs may be altered in pSS, identifying AQP4 as a promising new therapeutic agent to treat xerostomia.

引自

Sisto M,Lorusso L,Ingravallo G, et al. Abnormal distribution of AQP4 in minor salivary glands of primary Sjögren'ssyndromepatients.Autoimmunity.2017 Jun 24:1-9. doi: 10.1080/08916934.2017.1341495. [Epub ahead of print]