Analysis of the pathogenesis of inflammatory bowel disease using experimental colitis induced by a murine retrovirus

背景：已知LP-BM5小鼠白血病病毒(MuLV)可诱发小鼠艾滋病(MAIDs)。我们已经证明，有女仆的小鼠可以诱发干燥综合征(Sjogren‘s综合征，SjS)样外分泌病，过继转移来自女仆的小鼠的脾细胞可以在裸鼠中诱导炎症性肠病样结肠炎和SjS样外分泌病。目的：为探讨干扰素-g和白介素10在实验性结肠炎发病机制中的作用，我们试图鉴定产生这些细胞因子的细胞及其在结肠炎原位病变中的定位。方法：将4周龄C57BL/6(B6)小鼠接种Lp-BM5-MuLV，感染后8周取淋巴组织细胞接种于B6裸鼠体内。细胞移植4到6周后，有腹泻、肛门出血和体重减轻等临床症状的小鼠被处死，检查它们的结肠。用…法检测干扰素-g和IL-10mRNA的表达用双染色免疫荧光(IF)法分析这些细胞因子在冰冻切片中的蛋白表达。结果：所有接种辅助淋巴结细胞的小鼠均出现结肠炎和全身外分泌病，并在细胞移植后6周内死亡。可见散在的结肠糜烂。粘膜和粘膜下层以CD4+细胞为主，呈弥漫性分布。结肠上皮内淋巴细胞中可见少量CD8+细胞。Mac-1+细胞通常弥漫性地分布于固有层内，在受损的上皮细胞下具有特征性。B220+细胞定位于淋巴滤泡内。结肠炎组小鼠结肠组织中的干扰素-g和IL-10m RNA表达明显增加，而对照组小鼠结肠组织中未见明显变化。双色免疫荧光染色显示Mac-1+细胞呈干扰素-g或IL-10阳性，大部分CD4+细胞呈IL-10阳性，而干扰素-g阳性的CD4+细胞数量较少。结论：在我们的实验性结肠炎模型中，Mac-1+巨噬细胞同时产生干扰素-g和IL-10，可能在结肠炎的发病机制中起重要作用。较少

BACKGROUND : LP-BM5 murine leukemia virus (MuLV) is known to induce murine AIDS (MAIDS). We have shown that sjogren's syndrome (SjS) -like exocrinopathy can be induced in mice with MAIDS and that adoptive transfer of spleen cells from MAIDS mice can induce inflammatory bowel disease-like colitis as well as SjS-like exocrinopathy in nude mice. AIM : To assess the role of interferon (IFN)-g and interleukin (IL)-10 in the pathogenesis of our experimental model, we tried to identify the cells producing these cytokines and their localization in the colitis lesions in situ. METHODS : Four-week-old C57BL/6 (B6) mice were inoculated intraperitoneally with LP-BM5 MuLV.Eight weeks after infection, lymph node cells prepared from the virus-infected mice were transferred to B6 nude mice. Four to six weeks after the cell transfer, mice with clinical symptoms such as diarrhea, anal bleeding and body weight loss were killed to examine their colons. Expression of mRNA for IFN-g and IL-10 was assessed b … More y RTPCR, and protein expression of these cytokines was also analyzed in frozen sections of colon by double color-staining immunofluorescence (IF). RESULTS : All of the mice inoculated with MAIDS lymph node cells showed colitis as well as systemic exocrinopathy, and died within 6 weeks after cell transfer. Scattered erosions of the colon were observed. CD4+ cells were dominant and distributed diffusely within the mucosal and submucosal layers. A few CD8+ cells were detected among the intraepithelial lymphocytes of the colon. Mac-1+ cells were usually localized diffusely within the lamina propria and characteristically detected beneath the injured epithelial cells. B220+cells were localized within lymph follicles. An increase of IFN- g and IL-10 mRNA was detected in the colon of mice with colitis, but not in that of control mice. Double color IF showed that Mac-1+ cells were positive for IFN-g or IL-10 and that most CD4+ cells were positive for IL-10, although the population of IFN-g-positive CD4+ cells was low.CONCLUSIONS : In our experimental colitis model, Mac-1+ macrophages which produce both IFN-g and IL-10 might play a crucial role in the pathogenesis of colitis in combination with CD4+ T cells. Less