Role of Host Factors in HIV Immunopathogenesis

宿主因素在 HIV 免疫发病机制中的作用

• 批准号: 6985996
• 负责人: Audrey Lewis Kinter
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6985996
• 关键词: HIV infections; Macaca; cell proliferation; cellular immunity; electron microscopy; flow cytometry; gene induction /repression; helper T lymphocyte; host organism interaction; human immunodeficiency virus; human tissue; immune response; immunologic techniques; immunopathology; immunoregulation; immunosuppression; in situ hybridization; leukocyte activation /transformation; molecular pathology; polymerase chain reaction; suppressor T lymphocyte; tissue /cell culture; virus infection mechanism; virus load; virus replication; HIV infections; Macaca; cell proliferation; cellular immunity; electron microscopy; flow cytometry; gene induction /repression; helper T lymphocyte; host organism interaction; human immunodeficiency virus; human tissue; immune response; immunologic techniques; immunopathology; immunoregulation; immunosuppression; in situ hybridization; leukocyte activation /transformation; molecular pathology; polymerase chain reaction; suppressor T lymphocyte; tissue /cell culture; virus infection mechanism; virus load; virus replication

Since its inception, the Immunopathogenesis Section has defined host factors involved in the pathogenesis of HIV disease, including the impact of the immune system on the propagation and/or control of virus replication. Conversely, the LIR has demonstrated the the effects of high levels of circulating HIV on the function of numerous components of the immune system; however, little is known regarding the potential role of endogenous suppression of HIV-specific immune responses in HIV disease. This project was designed to evaluate the potential role of immunosuppressive CD25+CD4+ regulatory T (Treg) cells in the dysfunction of HIV-specific responses in chronically HIV-infected subjects. In addition, the direct and indirect effects of CD25+ Treg cells on HIV replication were assessed. CD25+ CD4+ T cells isolated from the peripheral blood of HIV-infected donors included a subpopulation that expressed the cell surface and nuclear antigen phenotype characteristic of CD25+hi regulatory CD4+ T cells (Treg). The CD25+ CD4+ T cell subset was found to reduce, but not completely suppress, both CD4+ and CD8+ HIV-specific T cell proliferation and effector cytokine production in the majority of healthy asymptomatic HIV-infected subjects tested. As previously reported, CD25+hi Treg-mediated suppression was not significantly overcome by neutralization of IL-10 or TGF-beta. Unexpectedly, among individuals possessing HIV-specific CD4+ T helper responses, those who did not exhibit strong in vitro HIV-specific CD25+CD4+ Treg suppressor activity had a less favorable clinical status than those in whom this activity was detected. CD25+CD4+ Treg activity directed against allogeneic antigens was detected in most HIV-infected individuals regardless of the presence or absence of HIV-specific Treg cells. These data suggest that CD25+CD4+ Treg-mediated immunosuppression may play a role in the diminution of HIV-specific CD4+ and CD8+ T cell responses early in disease, but that other factors associated with HIV infection obscure or reduce this activity in individuals with more advanced disease. Furthermore, the association between the presence of functional HIV-specific Treg cells in the peripheral blood and a favorable clinical status suggests that host-mediated suppressive mechanisms may have potential benefits in the context of chronic immune activation such as that observed in HIV disease. The direct and indirect effects of CD25+CD4+ regulatory T cells on HIV replication were also investigated. CD25+CD4+ T cells isolated from HIV-infected subjects were tested for their effects on the HIV suppressive activities of autologous CD8+ T cells. Short term exposure to CD25+, but not CD25-, CD4+ T cells during polyclonal activation of CD8+ T cells resulted in a significant (up to 99 %) reduction in both soluble and cell contact-mediated suppression of endogenous HIV replication by CD8+ T cells. These effects required cell contact between CD25+CD4+ and CD8+ T cells. Supernatants derived from CD8+ T cells exposed to CD25+ cells were found to contain lower levels of RANTES and MIP-1beta, potent inhibitors of R5 HIV entry, than control supernatants. Loss of CD8+ T cell contact-mediated HIV suppressive activity resulting from short-term exposure to CD25+ CD4+ T cells was associated with significant reductions in the expression levels of surface activation markers and proliferation (CFSE) of CD8+ T cells over the period of virus isolation. The direct effects of CD25+CD4+ Treg-like cells on HIV replication were assessed using cellular subsets obtained from HIV uninfected subjects. CD25+CD4+ Treg-like cells that were generated in vitro expressed surface and nuclear markers consistent with fresh CD25+ Treg cells. Autologous CD4+ T cells pre- exposed to HIV produced significantly less virus following co-culture with uninfected CD25+ Treg-like cells as compared to control cells. In addition, CD25+ Treg-like cells were found to inhibit viral gene expression in HIV-exposed CD4+ T cells using single round replication competent HIV. Furthermore, direct infection of Treg-like cells resulted in very poor HIV production. These results have been confirmed using freshly isolated CD25+ Treg cells. Taken together, these data suggest that the potential impact of CD25+Treg cells on HIV immunopathogenesis is extremely complex and may include both detrimental and beneficial effects. A second project was designed to investigate the role of host factors in the generation and/or maintenance of cellular reservoirs of HIV. We have demonstrated that the lymphoid tissue microenvironment is very supportive of productive HIV infection in resting CD4+ T cells, a well described cellular reservoir of HIV. Using an in vitro human lymphoid tissue (tonsil) culture model, we have found that purified resting CD4+ T cells produced HIV mRNA, p24 protein and infectious virus while maintaining a resting, non-dividing T cell phenotype when re-introduced into the microenvironment of autologous lymphoid tissue, but not when cultured alone. HIV production from this cellular population was driven, in part, by pro-inflammatory cytokines and additional signals generated by the tissue matrix. These data repudiate the paradigm that HIV production in T cells requires classical T cell activation and demonstrate that the lymphoid tissue is an ideal microenvironment for suboptimal cellular activation leading to HIV replication in phenotypically resting CD4+ T cells.

自从其成立以来，免疫病变部分已定义了涉及HIV疾病发病机理的宿主因素，包括免疫系统对病毒复制的传播和/或控制的影响。相反，LIR证明了高水平循环HIV对免疫系统众多成分功能的影响。但是，关于内源性抑制HIV特异性免疫反应在HIV疾病中的潜在作用知之甚少。该项目旨在评估免疫抑制CD25+ CD4+调节t（Treg）细胞在慢性HIV感染受试者中HIV特异性反应功能障碍中的潜在作用。另外，评估了CD25+ Treg细胞对HIV复制的直接和间接作用。从HIV感染供体的外周血中分离出的CD25+ CD4+ T细胞包括表达细胞表面的亚群和CD25+ HI调节性CD4+ T细胞（Treg）的核抗原表型的特征。发现CD25+ CD4+ T细胞子集可在大多数健康无症状的HIV受试者中降低但并非完全抑制CD4+和CD8+ HIV特异性T细胞增殖和效应细胞因子产生。如前所述，CD25+HI Treg介导的抑制是通过中和IL-10或TGF-β无法显着克服的。出乎意料的是，在具有HIV特异性CD4+ T辅助反应的个体中，那些未表现出强大的体外HIV特异性CD25+ CD4+ Treg抑制剂活性的人的临床状况低于检测到这种活性的人。在大多数HIV感染者中检测到针对同种异体抗原的CD25+ CD4+ Treg活性，而不管HIV特异性Treg细胞的存在或不存在。这些数据表明，CD25+ CD4+ Treg介导的免疫抑制可能在疾病早期早期HIV特异性CD4+和CD8+ T细胞反应的减少中起作用，但与HIV感染相关的其他因素掩盖或减少患有更晚期疾病的人的这种活性。此外，外周血中功能性HIV特异性Treg细胞的存在与有利的临床状况之间的关联表明，在慢性免疫激活的背景下，宿主介导的抑制机制可能具有潜在的益处，例如观察到的HIV疾病。还研究了CD25+ CD4+调节T细胞对HIV复制的直接和间接作用。测试了从HIV感染受试者分离的CD25+ CD4+ T细胞对自体CD8+ T细胞的HIV抑制活性的影响。在CD8+ T细胞多克隆激活期间，短期暴露于CD25+，但不暴露于CD25-，CD4+ T细胞中，可在可溶性和细胞接触介导的CD8+ T细胞对内源性HIV复制的抑制抑制CD8+ T细胞的抑制显着降低（高达99％）。这些影响需要CD25+ CD4+和CD8+ T细胞之间的细胞接触。发现源自接触CD25+细胞的CD8+ T细胞的上清液中，与对照上清液相比，含有较低水平的Rantes和MIP-1Beta，有效的R5 HIV进入的有效抑制剂，有效的R5 HIV进入抑制剂。在病毒分离期间，CD25+ CD4+ T细胞的CD8+ T细胞接触介导的HIV抑制活性的丧失与CD8+ T细胞的表面激活标记表达水平和CD8+ T细胞的增殖（CFSE）的显着降低有关。使用从HIV未感染的受试者获得的细胞亚群来评估CD25+ CD4+ Treg样细胞对HIV复制的直接影响。 CD25+ CD4+ Treg样细胞是在体外表达的表面和与新鲜CD25+ Treg细胞一致的核标记。与对照细胞相比，与未感染的CD25+ TREG样细胞共培养后，自体CD4+ T细胞与未感染的CD25+ Treg样细胞共同培养后产生的病毒明显较少。此外，发现使用单圆复制竞争的HIV，发现CD25+ Treg样细胞抑制了暴露于HIV的CD4+ T细胞中的病毒基因表达。此外，直接感染Treg样细胞导致HIV产生非常差。使用新鲜分离的CD25+ Treg细胞证实了这些结果。综上所述，这些数据表明，CD25+Treg细胞对HIV免疫发病发生的潜在影响非常复杂，可能包括有害和有益作用。 第二个项目旨在研究宿主因素在艾滋病毒的细胞储层生成和/或维持中的作用。我们已经证明，淋巴组织微环境非常支持静息CD4+ T细胞中的生产性HIV感染，这是HIV的细胞储层。使用体外人类淋巴组织（扁桃体）培养模型，我们发现纯化的静息CD4+ T细胞会产生HIV mRNA，p24蛋白和感染性病毒，同时保持静止的，非分裂的T细胞表型，当重新介绍到自动淋巴机的微环境中，但在培养的自动性淋巴机的微环境中，但并非培养。该细胞种群的HIV产生部分是由促炎性细胞因子和组织基质产生的其他信号驱动的。这些数据否认了T细胞中HIV的产生需要经典的T细胞激活的范例，并证明淋巴组织是次级细胞活化的理想微环境，从而导致表型静止的CD4+ T细胞中的HIV复制。