Study on the pathogenic mechanism of opportunistic fungal infectious diseases in AIDS patients

我们利用肺和播散性感染小鼠模型研究了基于细胞因子的宿主防御隐球菌病的机制。我们证明了Th1-Th2细胞因子合成的不平衡与感染的致命结果密切相关：也就是说，在感染高毒力的新生C.菌株时，在原发感染部位，Th2细胞因子的产生高于Th1，这些小鼠在感染后6周全部死亡，而IL-12治疗通过将不平衡的细胞因子合成转化为Th1优势状态而拯救了它们。有趣的是，该菌株抑制了巨噬细胞IL-12的产生，但没有或相反地增强了IL-10的合成，这可能表明这种机制参与了细胞因子平衡向Th2优势状态转移的过程。此外，在致死性感染模型中，CC趋化因子如MCP-1、RANTES、MIP-1α和MIP-1β以及CXC趋化因子IP-10在肺中产生的淋巴细胞和巨噬细胞的运输较少。同时，由淋巴细胞和巨噬细胞组成的炎性白细胞的积累也很差。IL- 12处理诱导肺中淋巴细胞和巨噬细胞的显著积累以及多核巨细胞的形成，这与这些单核白细胞运输趋化因子的产生非常一致。在我们最近的研究中，我们用IL-12、IL-18和IL-12/IL-18KO小鼠证明了IL-12和IL-18在宿主防御隐球菌感染中的重要作用。在这些小鼠中，与野生型小鼠相比，IFN-γ合成和宿主对微生物的抗性和DTH反应受到损害。IL-12KO小鼠比IL-18KO小鼠损伤更严重。在il - 12/IL-18KO小鼠中，IFN-γ的产生几乎完全被消除，宿主防御功能与IFN-γ - ko小鼠一样严重受损。与这些结果一致的是，用IL-12或IL-18治疗可增强宿主对新生假体致命感染的保护作用。前一种细胞因子的活性大于后一种细胞因子。在体外和体内研究中，联合使用这两种诱导IFN-γ的细胞因子可协同诱导IFN-γ的产生，增强宿主对该病原体的抗性。在我们的其他研究中，我们首先证明了宿主对青霉菌感染的防御是由细胞免疫介导的。我们发现，裸鼠对曼尼菲疟原虫感染高度敏感，正常小鼠的T细胞富集脾细胞过继转移使裸鼠对这种感染具有抵抗力。此外，我们证明了小鼠巨噬细胞的杀真菌活性是由一氧化氮介导的，而不是由超氧阴离子介导的，而人类中性粒细胞的这种活性可以被各种细胞因子增强，如GM-CSF、G-CSF、IL-8。TNF-γ和IFN-γ以及GM-CSF的作用是由颗粒酶介导的，而不是由氧自由基介导的。少

We have studied on the mechanism of cytokine-based regulation for host defense against cryptococcosis using a murine model of pulmonary and disseminated infection. We demonstrated that imbalance of Th1-Th2 cytokine production was well associated with the fatal outcome of infection: that is, in infection with a highly virulent strain of C. neoformans, Th2 cytokine production was dominant over Th1 in the primary infection site and these mice all died with 6 weeks post-infection, while IL-12 treatment saved them by converting the imbalanced cytokine synthesis to Th1-dominant condition. Interestingly, this strain suppressed the IL-12 production but did not or rather enhanced the synthesis of IL-10 by macrophages, which may suggest the involvement of this mechanism in the shifted cytokine balance toward Th2 predominant condition.Furthermore, in the fatal infection model, CC chemokines, such as MCP-1, RANTES, MIP-1α and MIP-1β, and IP-10, a CXC chemokine, all of which are important for the t … More rafficking of lymphocytes and macrophages were poorly produced in lungs. Compatibly, the accumulation of inflammatory leukocytes composing of lymphocytes and macrophages was found very poor. IL- 12 treatment induced the marked accumulation of lymphocytes and macrophages and formation of multinuclear giant cells in the lungs, which was well consistent with the production of these mononuclear leukocyte-trafficking chemokines.In our recent study, we have demonstrated the essential role for IL-12 and IL-18 in host defense against cryptococcal infection using IL-12, IL-18 and IL-12/IL-18KO mice. In these mice, IFN-γ synthesis and host resistance and DTH response to the microorganism were impaired compared to those in wild-type mice. The impairment was more profound in IL-12KO mice than in IL-18KO mice. In IL12/IL-18KO mice, IFN-γ production was almost completely abrogated and host defense was as profoundly impaired as in IFN-γKO mice. Compatibly with these results, treatment with either IL-12 or IL-18 increased the host protection against fatal infection with C. neoformans. Such activity was greater in the former cytokine than in the latter. Combined treatment with these two IFN-γ-inducing cytokines synergistically induced the production of IFN-γ and potentiated the host resistance to this pathogen both in in vitro and in vivo studies.In our other studies, we firstly demonstrated that host defense to Penicillium infection was mediated by cellular immunity. We showed that nude mice were highly susceptible to the infection with P. marneffei and that adoptive transfer of T cell-enriched spleen cells from normal mice rendered nude mice resistant to this infection. Furthermore, we demonstrated that fungicidal activity of murine macrophages was mediated by nitric oxide, not by superoxide anion and that such activity of human neutrophils was potentiated by various cytokines, such as GM-CSF, G-CSF, IL-8. TNF-γ and IFN-γ and the GM-CSF effect, which was most potent, was mediated by granular enzymes, not by oxygen radicals. Less