干燥综合征(Sjogren's syndrome, SS)是一个病因未明、主要累及唾液腺、泪腺等外分泌腺的慢性炎症性自身免疫病，发病机制尚未完全阐明，但是目前国际上比较一致的观点是，在各种内外因素作用下，缓慢而持久的免疫活化导致Fas介导的唾液腺上皮细胞凋亡是SS发病的主要机制。脂筏(lipid raft)是哺乳动物细胞质膜中存在的一种信号转导蛋白的特殊脂质微区域，参与细胞信号转导，细胞分化、增殖、凋亡等多种病理生理过程。本课题采用低温蔗糖密度梯度离心法分离纯化干燥综合征及健康对照原代培养的唾液腺上皮细胞膜脂筏，采用免疫沉淀、免疫印迹及共聚焦显微镜免疫荧光双标记等技术观察到活化后的Fas、CD40在唾液腺上皮细胞膜脂筏中簇集。我们发现anti-CD40 mAb刺激后Fas迁移入脂筏，同时Fas、FADD、procaspase-8共定位于富含鞘脂和胆固醇的细胞膜脂筏上，产生神经酰胺。胆固醇鳌和剂nystain和酸性鞘磷脂酶抑制剂imipramine可抑制这一活化过程及凋亡信号。结果表明脂筏及神经酰胺分子参与调控Fas、CD40-介导的干燥综合征病人唾液腺上皮细胞凋亡。

Sjogren's syndrome(SS) is an autoimmune disorder characterized by a progressive, immune-mediated destruction of mucosal tissues such as the lacrimal and salivary glands, leading to ocular and oral dryness. The mechanism of the exocrine gland dysfunction is not clearly understood, but accelerated apoptosis has been suggested as one explanation for the dysfunction, although the pathogenesis of SS is multifactorial. Membrane microdomains known as lipid rafts have been shown recently to be involved in Fas signalling and apoptosis in mammal animal cells. Here, we have investigated further the role of lipid rafts in CD40 medicated Fas-dependent apoptosis in human salivary epithelial cells. Lipid rafts have be isolated and purified by sucrose density gradients centrifugation at low temperature in primary cultured saliviary epithelial cells from patients with SS and healthy controls. We showed that the Fas translocated into membrane rafts following anti-CD40 mAb treatment of salivary epithelial cells. This process could be inhibited by disruption of membrane raft integrity by methylb-cyclodextrin or the inhibitor of acid sphingomyelinase (aSMase) imipramine and the cholesterol sequestering agent nystatin. We also found that methylb-cyclodextrin, imipramine, and nystain could decreases CD40-induced Fas-dependent apoptos

干燥综合征(Sjogren's syndrome, SS)是一个病因未明、主要累及唾液腺、泪腺等外分泌腺的慢性炎症性自身免疫病，发病机制尚未完全阐明，但是目前国际上比较一致的观点是，在各种内外因素作用下，缓慢而持久的免疫活化导致Fas介导的唾液腺上皮细胞凋亡是SS发病的主要机制。脂筏(lipid raft)是哺乳动物细胞质膜中存在的一种信号转导蛋白的特殊脂质微区域，参与细胞信号转导，细胞分化、增殖、凋亡等多种病理生理过程。本课题采用低温蔗糖密度梯度离心法分离纯化干燥综合征及健康对照原代培养的唾液腺上皮细胞膜脂筏，采用免疫沉淀、免疫印迹及共聚焦显微镜免疫荧光双标记等技术观察到活化后的Fas、CD40在唾液腺上皮细胞膜脂筏中簇集。我们发现anti-CD40 mAb刺激后Fas迁移入脂筏，同时Fas、FADD、procaspase-8共定位于富含鞘脂和胆固醇的细胞膜脂筏上，产生神经酰胺。胆固醇鳌和剂nystain和酸性鞘磷脂酶抑制剂imipramine可抑制这一活化过程及凋亡信号。结果表明脂筏及神经酰胺分子参与调控Fas、CD40-介导的干燥综合征病人唾液腺上皮细胞凋亡。