INVOLVEMENT OF APOPTOTIC PATHWAY IN PATHOGENESIS OF SJOGRENS SYNDROME

在本研究中，我们使用自身免疫模型小鼠mrl/lpr和对照小鼠mrl/+小鼠，用免疫组织化学方法研究了肿瘤坏死因子α介导的和线粒体介导的细胞凋亡途径在干燥综合征发病机制中的作用。每个品系的5个月大的小鼠在麻醉过量后失血后被处死。取出颌下腺，用10%缓冲福尔马林固定，石蜡包埋。石蜡包埋组织切片(3μm)采用链霉亲和素-生物素方法，对肿瘤坏死因子α、肿瘤坏死因子受体1、FADD、半胱氨酸天冬氨酸蛋白酶8、半胱氨酸天冬氨酸氨基转移酶3，以及与线粒体介导的细胞凋亡相关的半胱氨酸天冬氨酸氨基转移酶2、BID、PUMA Bax、细胞色素c、APSF-1、半胱氨酸天冬氨酸蛋白酶9进行免疫组织化学染色。MRL/LPR小鼠的标本显示这些配体在颌下腺的导管细胞中有强烈的表达。然而，这些配体在MRL/+小鼠体内的免疫定位较弱且不能令人信服。已有研究表明，干燥综合征唾液腺的组织破坏是由细胞凋亡引发的，Fas-Fas配体凋亡通路在该疾病的发病机制中起着至关重要的作用。我们还证实，MRI/LPR小鼠颌下腺组织的受损归因于通过单链DNA表达而导致的细胞凋亡。此外，MRL/LPR小鼠由于携带Fans基因突变，其Fas-Fas配体的凋亡通路被取消。因此，我们目前的研究表明，肿瘤坏死因子α和线粒体介导的凋亡途径而不是Fas-Fas配体的凋亡途径与干燥综合征样涎腺炎的发生发展有关。

We examined immunohistochemically the involvement of TNF α-mediated and mitochondria-mediated apoptotic pathway in pathogenesis of Sjogren's syndrome using autoimmune model mouse, MRL/lpr mice, and control mice, MRL/+ mice, in our present study. 5-month-old mice of each strain were sacrificed by anesthesia overdose followed by exsanguinations. Submandibular glands were removed, fixed in 10% buffered formalin, and embedded in paraffin. Paraffin-embedded tissue sections (3μm) were immunostained against TNF α, TNF receptor 1, Fadd, caspase 8, caspase 3, which are implicated in TNF α-mediated apoptotic pathway, in addition to caspase 2, Bid, p53, PUMA Bax, cytochrome c, Apsf-1, caspase 9, which are related to mitochondria-mediated apoptosis, using streptoavidin-biotin method. The specimens of MRL/lpr mice showed intense expression of these ligands in ductal cells of submandibular glands. However, the immunolocalizations of these ligands in MRL/+ mice were weak and not convincing.It has been revealed that tissue destruction of salivary glands observed in Sjogren's syndrome is triggered by apoptosis, and Fas-Fas ligand apoptotic pathway plays a crucial role in the pathogenesis of this disease. We have also confirmed that, impaired submandibular gland tissues of MRI/lpr mice attribute to the commitment to apoptosis through ssDNA expression. Furthermore, Fas-Fas ligand apoptotic pathway is abrogated in MRL/lpr mice because they carry a mutant of fans gene. Therefore, our present, study indicates that TNF α-mediated and mitochondria-mediated apoptotic pathway other than Fas-Fas ligand apoptotic pathway has the association with the development, of Sjogren's syndrome-like sialadenitis in MRL/lpr mice.