Inhibitory effects of autoantibodies on the muscarinic receptors in Sjogren's syndrome
Inhibitory effects of autoantibodies on the muscarinic receptors in Sjogren's syndrome
复制标题
DOI：
10.1038/labinvest.3700173
复制
发表时间：
2004-11-01
影响因子：
5
通讯作者：
Park, K
中科院分区：
文献类型：
--
作者：
Li, JC;Ha, YM;Park, K
干燥综合征（SS）是一种全身性自身免疫性疾病，涉及唾液分泌减少。最近，循环自身抗体从SS患者对3型毒蕈碱胆碱能受体（M3 R）已报告在SS患者的血清中。然而，这些自身抗体在SS发展中的作用尚未阐明。在这项研究中，纯化的IgG从11 SS患者的血清中获得，并使用RT-PCR，显微荧光光谱法，免疫组织化学和Western印迹分析其对唾液腺M3 R的抑制作用进行了评价。氨甲酰胆碱（CCh）刺激引起[Ca 2 +]（i）在Fura-2负载的HSG细胞瞬变。然而，用SS IgG（0.5 mg/ml）预处理细胞12或24 h显著降低了CCh诱导的[Ca 2 +]（i）瞬变（CICT）的幅度。我们发现，当用SS IgG预处理细胞时，CICT的幅度降低了62 - 45%。然而，[Ca ~（2+）]（i）对ATP的反应并不因SS IgG的预处理而改变。SS IgG对CICT的影响被废除的过度竞争的肽，编码的氨基酸序列的M3 R，这是不概括的非特异性肽的列入。SS IgG对水通道蛋白（AQP）-5表达的抑制作用也被检测。在证实了水通道蛋白5沿着位于顶端后，我们用大鼠腮腺腺泡细胞检测了SS IgG是否对毛果芸香碱诱导的水通道蛋白5向顶端膜（APM）的运输有影响。与SS IgG孵育12 h后，毛果芸香碱诱导的AQP-5的量与对照组相比显著降低。总之，来自SS患者的自身抗体抑制由Ca 2+动员和AQP-5运输介导的人M3 R的功能。我们的结果可以部分解释SS患者腺体功能障碍的潜在机制和相关的自主神经功能受损的特点。
Sjogren's syndrome (SS) is a systemic autoimmune disease that involves reduced salivary secretions. Recently, circulating autoantibodies from SS patients against the type 3 muscarinic cholinergic receptor (M3R) has been reported in the sera of SS patients. However, the role of these autoantibodies in the development of SS has not been elucidated. In this study, purified IgG was obtained from the sera of 11 SS patients, and its inhibitory effect on the M3R of the salivary glands was evaluated using RT-PCR, microspectrofluorimetry, immunohistochemistry, and Western blot analysis. Stimulation with carbachol (CCh) evoked a [Ca2+](i) transient in the fura-2 loaded HSG cells. However, pretreatment of the cells with SS IgG (0.5 mg/ml) for 12 or 24 h significantly reduced the magnitude of the CCh-induced [Ca2+](i) transient (CICT). We found that the magnitude of CICT was decreased by 62 - 45% when cells were pretreated with the SS IgG. However, the [Ca2+](i) response to ATP was not altered by the pretreatment of SS IgG. The effect of SS IgG on CICT was abrogated by the inclusion of excessive competitive peptides that encode the amino-acid sequence of M3R, which was not recapitulated by nonspecific peptides. The inhibitory effect of SS IgG on the aquaporin (AQP)-5 expression was also examined. After confirming the apical localization of AQP-5 along with its increase by pilocarpine ( 10(-5) M), we examined whether SS IgG had an effect on pilocarpine-induced AQP-5 trafficking to the apical membrane (APM) using rat parotid acinar cells. After incubating the cells with SS IgG for 12 h, the amount of pilocarpine-induced AQP-5 significantly decreased compared to the control groups. In conclusion, autoantibodies from the SS patients inhibit the function of the human M3R that is mediated by Ca2+ mobilization and AQP-5 trafficking. Our results could partly explain the underlying mechanisms of glandular dysfunction and associated features of impaired autonomic function in SS patients.