Garcia I, Miyazaki Y, Marchal G, Lesslauer W, Vassalli P
Department of Pathology, C.M.U., Geneva, Switzerland.
Eur J Immunol. 1997 Dec;27(12):3182-90. doi: 10.1002/eji.1830271215.
To investigate the role of tumor necrosis factor (TNF) in protective immune responses to Mycobacterium tuberculosis and M. bovis Bacillus Calmette Guérin (BCG), we have used transgenic mice unable to use TNF because of the expression of high amounts of a soluble TNF receptor (R) type I (sTNFR1) fusion protein, and studied resistance of these mice to infection by lethality assays, evaluation of bacterial recovery and histologic examination. These mice showed a strongly increased sensitivity to M. tuberculosis and BCG infections, with bacterial overgrowth and marked inhibition of macrophage differentiation within granulomas; after M. tuberculosis infection, this resulted in extensive lesions of caseous necrosis in the lung. To explore the respective roles of TNF and interferon (IFN)-gamma in resistance to BCG and granuloma differentiation, controls and sTNFR1-transgenic mice were compared to IFN-gammaR mutant mice and mice double defective in TNF and IFN-gamma activity (obtained by crossing transgenic and mutant mice). The three groups of deficient mice showed a strongly enhanced susceptibility to BCG infection, with the following decreasing order of sensitivity between groups: TNF + IFN-gamma --> TNF --> IFN-gamma-deficient mice. The hepatic granulomas of IFN-gammaR mutant mice were small and contained eosinophils but few differentiated macrophages; compared to those of sTNFR1-transgenic mice, acid-fast bacilli were less numerous within the macrophages. Granulomas of double-deficient mice were strikingly different by their very large size and cellular content, made up large numbers of polymorphonuclears, eosinophils, and cells undergoing apoptosis, but without detectable differentiated macrophages; acid-fast bacilli were spread in the lesions. These studies show the essential role of both TNF and IFN-gamma in the development, during mycobacterial infections, of protective granulomas containing highly differentiated macrophages capable of destroying ingested bacteria, and emphasize that these two cytokines act synergistically in granuloma formation.
为了研究肿瘤坏死因子（TNF）在针对结核分枝杆菌和牛型结核分枝杆菌卡介苗（BCG）的保护性免疫反应中的作用，我们使用了由于大量表达可溶性I型TNF受体（R）融合蛋白而无法利用TNF的转基因小鼠，并通过致死率测定、细菌回收评估和组织学检查来研究这些小鼠对感染的抵抗力。这些小鼠对结核分枝杆菌和BCG感染的敏感性显著增加，伴有细菌过度生长以及肉芽肿内巨噬细胞分化的明显抑制；结核分枝杆菌感染后，这导致肺部出现广泛的干酪样坏死病变。为了探究TNF和干扰素（IFN）-γ在抵抗BCG和肉芽肿分化中的各自作用，将对照组和sTNFR1转基因小鼠与IFN-γR突变小鼠以及TNF和IFN-γ活性双缺陷小鼠（通过杂交转基因小鼠和突变小鼠获得）进行了比较。这三组缺陷小鼠对BCG感染的易感性均显著增强，各组之间的敏感性按以下顺序递减：TNF + IFN-γ缺陷小鼠>TNF缺陷小鼠>IFN-γ缺陷小鼠。IFN-γR突变小鼠的肝肉芽肿较小，含有嗜酸性粒细胞但分化的巨噬细胞很少；与sTNFR1转基因小鼠的相比，巨噬细胞内抗酸杆菌数量较少。双缺陷小鼠的肉芽肿在大小和细胞成分上明显不同，由大量多形核细胞、嗜酸性粒细胞和正在凋亡的细胞组成，但没有可检测到的分化巨噬细胞；抗酸杆菌散布在病变中。这些研究表明，TNF和IFN-γ在分枝杆菌感染期间形成含有能够破坏摄入细菌的高度分化巨噬细胞的保护性肉芽肿过程中都起着至关重要的作用，并强调这两种细胞因子在肉芽肿形成中协同作用。
