抗M3R抗体的结合受体后抑制AQP5导致干燥综合症分泌功能受损
发表者：杨麟
日期：2015-03-04
浏览次数：267
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摘要：M3R属于G蛋白偶联受体（GPCR）家族，包括亚型m1r-m5r。M3R Gq蛋白/ 11可通过毒蕈碱受体激动剂如乙酰胆碱或卡巴胆碱结合启动三磷酸磷脂酰肌醇级联，从而介导的细胞内钙存储的Ca2 +释放。升高细胞内Ca2+作用于动物腮腺腺泡细胞，从而引起唾液分泌。水通道蛋白5（AQP5）是一个主要的水转运蛋白，根据Ca2 +浓度的变化的调节唾液的分泌。有研究表明，大鼠AQP5能人涎腺细胞（HSG）细胞转运到相应的细胞膜，增加细胞内Ca2 +浓度。一直存在争议的是抗毒蕈碱受体3型（α- M3R）是否与干燥综合症患者自身抗体抑制水通道蛋白5（AQP5）有关，从而导致了细胞内转运蛋白的失常，导致分泌功能障碍。为了解决这个问题，GFP标记的人类AQP5转染了人涎腺细胞（HSG）并高表达（HSG-haqp5）同时监测在卡巴胆碱（CCH，M3R激动剂）刺激下的AQP5的转运。结果显示当M3R拮抗剂4-DAMP后，AQP5的转运的确受M3R的调控。HSG-haqp5与干燥综合症患者血浆预孵育24小时，显著降低了AQP5的转运。这种抑制作用通过单克隆抗 M3R抗体所证实。有趣的是，HSG-haqp5与干燥综合症患者的血浆预孵育显示细胞体积没有变化，而与健康对照的血浆预孵育后细胞体积显示收缩20%。研究者的研究结果清楚地表明，抗M3R抗体的结合受体后抑制AQP5转运膜从而导致干燥综合症分泌功能受损。我们目前的研究进一步说明了干燥综合症的临床表现和自身抗体谱的相关性急需进一步研究。
附原文：Abstract Sjögren's syndrome (SjS) is a chronic autoimmune disease that mainly targets the salivary and lacrimal glands. It has been controversial whether anti-muscarinic type 3 receptor (α-M3R) autoantibodies in patients with SjS inhibit intracellular trafficking of aquaporin-5 (AQP5), water transport protein, leading to secretory dysfunction. To address this issue, GFP-tagged human AQP5 was overexpressed in human salivary gland cells (HSG-hAQP5) and monitored AQP5 trafficking to the plasma membrane following carbachol (CCh, M3R agonist) stimulation. AQP5 trafficking was indeed mediated by M3R stimulation, shown in partial blockage of trafficking by M3R-antagonist 4-DAMP. HSG-hAQP5 pre-incubated with SjS plasma for 24 hours significantly reduced AQP5 trafficking with CCh, compared with HSG-hAQP5 pre-incubated with healthy control (HC) plasma. This inhibition was confirmed by monoclonal α-M3R antibody and pre-absorbed plasma. Interestingly, HSG-hAQP5 pre-incubated with SjS plasma showed no change in cell volume, compared to the cells incubated with HC plasma showing shrinkage by twenty percent after CCh-stimulation. Our findings clearly indicate that binding of anti-M3R autoantibodies to the receptor, which was verified by immunoprecipitation, suppresses AQP5 trafficking to the membrane and contribute to impaired fluid secretion in SjS. Our current study urges further investigations of clinical associations between SjS symptoms, such as degree of secretory dysfunction, cognitive impairment, and/or bladder irritation, and different profiles (titers, isotypes, and/or specificity) of anti-M3R autoantibodies in individuals with SjS.
引自：Lee BH, Gauna AE, Perez G, Park YJ, Pauley KM, Kawai T, Cha S.Autoantibodies against muscarinic type 3 receptor in Sjögren's syndrome inhibit aquaporin 5 trafficking.PLoS One. 2013;8(1):e53113. （注：干燥综合症病人或亲属可加QQ群交流，群号： 118194945 ，本网站站长私人微信号： ssgzz88 ）
附原文：Abstract Sjögren's syndrome (SjS) is a chronic autoimmune disease that mainly targets the salivary and lacrimal glands. It has been controversial whether anti-muscarinic type 3 receptor (α-M3R) autoantibodies in patients with SjS inhibit intracellular trafficking of aquaporin-5 (AQP5), water transport protein, leading to secretory dysfunction. To address this issue, GFP-tagged human AQP5 was overexpressed in human salivary gland cells (HSG-hAQP5) and monitored AQP5 trafficking to the plasma membrane following carbachol (CCh, M3R agonist) stimulation. AQP5 trafficking was indeed mediated by M3R stimulation, shown in partial blockage of trafficking by M3R-antagonist 4-DAMP. HSG-hAQP5 pre-incubated with SjS plasma for 24 hours significantly reduced AQP5 trafficking with CCh, compared with HSG-hAQP5 pre-incubated with healthy control (HC) plasma. This inhibition was confirmed by monoclonal α-M3R antibody and pre-absorbed plasma. Interestingly, HSG-hAQP5 pre-incubated with SjS plasma showed no change in cell volume, compared to the cells incubated with HC plasma showing shrinkage by twenty percent after CCh-stimulation. Our findings clearly indicate that binding of anti-M3R autoantibodies to the receptor, which was verified by immunoprecipitation, suppresses AQP5 trafficking to the membrane and contribute to impaired fluid secretion in SjS. Our current study urges further investigations of clinical associations between SjS symptoms, such as degree of secretory dysfunction, cognitive impairment, and/or bladder irritation, and different profiles (titers, isotypes, and/or specificity) of anti-M3R autoantibodies in individuals with SjS.
引自：Lee BH, Gauna AE, Perez G, Park YJ, Pauley KM, Kawai T, Cha S.Autoantibodies against muscarinic type 3 receptor in Sjögren's syndrome inhibit aquaporin 5 trafficking.PLoS One. 2013;8(1):e53113. （注：干燥综合症病人或亲属可加QQ群交流，群号： 118194945 ，本网站站长私人微信号： ssgzz88 ）