Spotted Fever Rickettsial Antigens

严重斑点热立克次体病是威胁生命的、蜱传的、新发和复发的人类感染 由专性细胞内立克次体引起，包括R. conorii和R.立克次氏体优秀的动物模型和 现有的人类数据揭示了IFN-γ、CD 8细胞毒性T淋巴细胞、树突状细胞、 细胞（DC）和NK细胞在宿主针对立克次体的保护性免疫中的作用。人类立克次体的证据 淋巴细胞增殖的显著抑制支持感染相关的免疫抑制 在急性致死性鼠中通过产生IL-10的CD 4 + CD 25 + T调节细胞产生IL-2和IFN-γ 斑点热立克次体病与自限性感染相比。目前还不清楚为什么宿主防御系统 未能控制致命性立克次体病的细菌感染。这项研究的长期目标是更好地 了解宿主防御系统无法控制的免疫调节机制 感染严重斑点热立克次体病。本提案的目的是通过以下方式确定机制： 这些DC介导先天性缺陷和受抑制的适应性免疫应答， 细胞，这可能导致致命的立克次体感染。我们的具体目标1是确定受损的关键影响 DC-NK细胞相互作用促进严重斑点热立克次体病患者先天免疫应答缺陷 我们将比较易感小鼠中有缺陷的DC-NK细胞串扰，其导致进行性增加 细菌负荷，在耐药小鼠中具有有效的DC-NK细胞相互作用，导致细菌清除 在先天反应中。我们的具体目标2是确定免疫调节分子的作用， DC表达或产生的PD-1/PD-L和吲哚胺2，3-双加氧酶（IDO）或细胞因子如IL-10 和/或T调节细胞在严重斑点热立克次体病期间抑制T细胞应答中的作用。toll样 受体（TLR）、细胞因子和趋化因子，其介导特异性目的1中的DC-NK细胞相互作用，以及 树突状细胞与调节性T细胞的相互作用在介导受抑制的保护性效应1型T细胞中的作用 和/或通过抑制性细胞因子和/或调节分子（包括PD-1/PD-L和IDO）的细胞凋亡。 将使用体内和体外方法研究特定目标2中的严重斑点热立克次体病 包括流式细胞术、ELISPOT、ELISA、RT或真实的时间PCR、小鼠TLR PCR阵列， 免疫组化染色、空斑试验、HPLC以及过继转移、免疫耗竭 分子和基因敲除小鼠。

Severe spotted fever rickettsioses are life-threatening, tick-borne, emerging and re-emerging human infections caused by obligately intracellular Rickettsia including R. conorii and R. rickettsii. Excellent animal models and the available human data reveal the critical importance of IFN-gamma, CD8 cytotoxic T lymphocytes, dendritic cells (DCs) and NK cells in host protective immunity against Rickettsia. Evidence for human rickettsial infection-associated immunosuppression is supported by remarkable suppression of lymphocyte proliferation and IL-2 and IFN-gamma production by IL-10 producing CD4+CD25+ T regulatory cells in acute fatal murine spotted fever rickettsiosis compared to self-limited infection. It remains unclear why the host defense system fails to control bacterial infection in fatal rickettsiosis. The long-term goal of this research is to better understand the immune regulatory mechanisms involved in the inability of the host defense system to control infection in severe spotted fever rickettsiosis. The objective of this proposal is to determine the mechanisms by which DCs mediate defective innate and suppressed adaptive immune responses involving T regulatory 1 cells, which may lead to fatal rickettsial infection. Our specific aim 1 is to determine the key effect of impaired DC-NK cell cross talk on promoting a defective innate immune response in severe spotted fever rickettsiosis. We will compare the defective DC-NK cell cross talk in susceptible mice, which causes progressively increased bacterial loads, with efficient DC-NK cell interaction in resistant mice, which lead to clearance of bacteria during the innate response. Our specific aim 2 is to determine the role of immunoregulatory molecules such as PD-1/PD-L and indoleamine 2,3-dioxygenase (IDO) or cytokines such as IL-10 expressed or produced by DCs and/or T regulatory cells in suppression of T cell responses during severe spotted fever rickettsiosis. Toll-like receptors (TLRs), cytokines and chemokines that mediate the DC-NK cell interaction in specific aim 1, and the role of interactions of DCs with T regulatory cells in mediating suppressed protective effector type-1 T cells and/or apoptosis via suppressive cytokines and/or regulatory molecules including PD-1/PD-L and IDO in severe spotted fever rickettsiosis in specific aim 2 will be investigated using in vivo and in vitro approaches including flow cytometry, ELISPOT, ELISA, RT- or real time PCR, mouse TLR PCR array, immunohistochemical staining, plaque assay, HPLC as well as adoptive transfer, depletion of immune molecules and knockout mice.