共表达IL-6/BAFF的基因疫苗对干燥综合征动物模型的治疗作用

Sjögren's syndrome (SS) is the autoimmune disease characterized by lymphocytic infiltration. Much proof show B Cells play kinds of roles in incidence and development of SS and B-cell directed therapies seem to be more promising than T-cell directed therapies . IL-6 is important for B cells growth and differentiation and it is sought to induce the prodution of auto-reactive antibodies by infiltrating B cells. B cell activing factor (BAFF) is important of growth ,differentiation and activation of B cells. The expression levels of IL-6 and BAFF are high in SS patients, the high levels correlated with disease severity. So the study are designed to construct eukaryotic co-expression vector targeted IL-6 and BAFF which are important roles for B cell differentiation and activation. We will extracte fusion protein of IL-6 and BAFF after the vector is transfected into Chinese hamster ovary (CHO) cell and BALB/C mice are immunized by the gene vaccine. The expression levels, titer and duration of the antibody in serum are detected by ELISA method. Finally the study will observe the therapeutic effects on NOD mice after the gene vaccine are injected into NOD mice.

干燥综合征（Sjögren's syndrome，SS）是一种以淋巴细胞浸润为特征的自身免疫性疾病，大量的数据显示B细胞在SS的发生发展过程中起多重作用，而且B细胞的靶向治疗较T细胞的治疗效果更好。IL-6是B细胞生长和分化的重要因子，它可以诱导浸润的B细胞产生自身反应性抗体，B细胞活化因子（B-cell activating factor, BAFF），它来源于巨噬细胞和DC细胞，在B细胞的生存、分化及活化中起重要作用。本研究将针对B细胞分化和活化的两个重要细胞因子IL-6和BAFF构建双基因真核表达载体，制备基因疫苗，转染中国仓鼠卵巢（chinese hamster ovary，CHO）细胞表达融合蛋白并进行纯化，之后将基因疫苗免疫BALB/c小鼠，免疫结束后取血清检测抗体的表达水平、效价及持续时间，最后将基因疫苗免疫NOD小鼠，观察其对NOD小鼠的治疗作用。

干燥综合征（sjögren’s syndrome，SS）是以淋巴细胞浸润外分泌腺和B细胞高反应性为特点的一种缓慢进展的自身免疫性疾病。有研究发现B细胞活化因子(B cell activating factor，BAFF)在SS发病中发挥重要作用，SS患者血清及唾液腺中均发现BAFF的表达增高。SS患者唾液腺和血清中白细胞介素（interleukin，IL）-6水平明显升高，且与疾病表现呈正相关，本研究探讨IL-6和BAFF的共表达对干燥综合征动物模型非肥胖糖尿病小鼠（non-obese diabetic mouse，NOD）的治疗作用机制。结果发现成功构建的IL-6/BAFF的共表达载体使BALB/ c小鼠和NOD小鼠血清中抗IL-6抗体和抗BAFF抗体的水平升高；治疗组的NOD小鼠血清中IL-6和BAFF等细胞因子的表达水平低于空白组和阴性对照组；治疗组的NOD小鼠脾细胞中Treg、Th2、Tfr细胞比例增高，B1、B2细胞、Th17/Treg和Tfh/Tfr降低，与空白组和阴性对照组比较差异有统计学意义，Th17细胞和Tfh细胞的比例在3组之间没有明显的变化；治疗组的NOD小鼠胸腺细胞中Treg和Tfr细胞比例增高，B1、B2细胞、Th17/Treg和Tfh/Tfr降低，与空白组和阴性对照组比较差异有统计学意义，Th17细胞、Th2细胞和Tfh细胞的比例在3组之间没有明显的变化；治疗组中NOD小鼠泪腺及唾液腺中腺泡大小不一和形态不规则明显改善，导管扩张减轻，灶状淋巴细胞浸润减少；肺组织淋巴细胞细胞浸润及肺泡壁破坏减少、胶原纤维沉积和纤维化程度减轻。这些数据提示IL-6/BAFF共表达可诱导NOD小鼠体内抗IL-6抗体和抗BAFF抗体的产生；进而减轻炎症因子的表达水平；逆转Th17/ Treg、Th1/Th2和Tfh/Tfr的平衡；同时改善NOD小鼠泪腺及唾液腺内不规则的腺泡结构及导管扩张情况，减少灶状淋巴细胞浸润和肺组织淋巴细胞细胞浸润，减轻肺泡壁破坏、胶原纤维沉积和纤维化程度。表明IL-6/BAFF的共表达可以作为治疗NOD小鼠的潜在治疗靶点。