母牛分支杆菌菌苗对结核病小鼠Th1/Th2细胞动力学及诱导型一氧化氮合酶表达影响的研究

Mycobacterium vaccae influences the kinetics of Th1/Th2 cells and expression of iNOS in a marine model of experimental tuberculosis

目的 从分子病理学角度探讨母牛分支杆菌菌苗 (以下简称母牛菌苗 )的免疫调节机制。方法 将BALB/C小鼠随机分为 3组 :单纯攻毒组 (A)、母牛菌苗免疫攻毒组 (B)和正常对照组(N)。经尾静脉注射H37RV 建立结核病小鼠模型 ,母牛菌苗由腹腔注射。肉眼观察肺脏病变指数并采用免疫组化染色和常规HE染色 ,探讨IFN γ、IL 4、iNOS表达与肺脏组织损伤的类型和程度的关系。结果 结核病小鼠病变弥漫 ,伴有灶性干酪坏死 ,免疫组织化学染色结果显示在炎性渗出及肉芽肿内IFN γ阳性细胞随时间推移逐渐增多 ,至第 6周达高峰 (0 0 5 8± 0 0 10 ) ,与正常对照组比较有非常显著性差异 (0 0 0 5± 0 0 2 0 ,P <0 0 1)。此后为Tho平衡期 ,在肺损伤组织中IFN γ和IL 4阳性细胞基本相当。iNOS表达在急性期增多慢性期减少。母牛菌苗免疫攻毒组小鼠肺组织病变 ,以增殖结节、淋巴样结节为主 ,未见坏死病变 ,免疫反应表现为 :感染全过程中以Th1应答为主 ,即IFN γ阳性细胞逐渐增多 ,第 8周达高峰 (0 0 5 8± 0 0 10 ) ,IL 4阳性细胞一直维持在低水平 ,未出现Tho平衡期。iNOS表达一直维持在高水平。结论 母牛菌苗调节结核病小鼠免疫的可能机制为 :启动Th1应答 ,抑制Th2应答 ,激活iNOS活性 ,增强机体保护性免疫。

Objective To investigate the immunoregulative mechanism of Mycobacterium vaccae by way of molecular pathology Methods BALB/C mice were randomly divided into three groups: tuberculosis model (A); mice were challenged with H 37 R V by their tail veins and then immunized by M vaccae (B); control mice (N) Immunohistochemistry and pathological slices stained with HE were evaluated to investigate the correlation between the expression of IFN γ,IL 4 and iNOS and the type and magnitude of tissue injury Results A predominance of Th1 cells was observed manifested by a high percentage of IFN γ positive cells in the inflammatory infiltrate and granulomas demonstrated by immunohistology peaked 6 weeks after infection (0 058±0 010), and there was a significant increase compared with N group (0 005±0 020, P <0 01) This was followed by a chronic advanced phase characterized by pneumonia local necrosis with a Tho balance due to an equivalent proportion of IFN γ and IL 4 positive cells in the lung lesions The iNOS expression was increased in acute phase and decreased in chronic phase B group had localized lung lesions, proliferate and lymphoid nodules were predominant, there was less necrostic change A predominance of Th1 cells was observed during the infection changed over time and there was no Tho balance phase occurred iNOS expression had a higher level during the wholecourse of infection Conclusion M vaccae can enhance the protective immunological response by inducing Th1 response and inhibiting Th2 response