HIV PATHOGENESIS: DIFFERENTIAL EFFECTS ON LYMPHOCYTE SUBSETS

HIV在Th2和Th0细胞中的优先复制比在Th1细胞中的优先复制在艾滋病的发展过程中被提出。为了解决这个问题，我们用不同的HIV分离株感染了来自不同正常供体的人类辅助性T细胞（Th）克隆，并检查了HIV融合、进入和传染性的所有差异。我们的研究表明，人类T细胞和抗原特异性T细胞克隆在其表面表达大量的趋化因子受体，这些受体介导T细胞运输、脱颗粒和细胞内钙动员，并作为介导HIV-1进入这些细胞群的共受体。然而，尽管趋化因子受体表达存在这些差异，我们的研究表明，人类Th0、Th1和Th2克隆都能够感染各种T型、M型和双向性HIV-1毒株。与感染的Th2克隆（4-21天）相比，hiv -1感染的Th1克隆在体外表现出快速（1-5天）fas介导的细胞凋亡。在HIV-1感染后，在Th1而不是Th2克隆表面Fas配体的表达增加可能解释了CD4+ T细胞亚群更快的周转。对人类Th1和Th2克隆之间各种凋亡信号传导差异的进一步研究表明，大多数人类Th1而非Th2细胞易受激活诱导的细胞死亡（AICD）的影响。此外，大多数人类Th1克隆表达很少或不表达bcl-2和bcl-xl（抗凋亡蛋白），使它们更容易受到各种凋亡刺激以及hiv -1介导的细胞死亡。相比之下，人类Th2克隆表达更高水平的bcl-2和bcl-xl，并且发现对凋亡和hiv -1介导的细胞病变作用不太敏感。因此，表达bcl的T细胞免受HIV诱导的细胞死亡的保护表明，细胞凋亡不仅有助于HIV感染杀死细胞，而且可能允许选择性破坏周围的Th1细胞，导致循环中th2样淋巴细胞的增加。这种增加的Th1克隆对hiv介导的细胞死亡的易感性表明hiv诱导的艾滋病免疫抑制的主要机制。我们发现Th1和Th2克隆在某些细胞表面趋化因子受体的表达上也存在差异，这可能是Th亚群易感性增加的原因。我们认为Th0-Th1到Th2的转换发生在许多慢性炎症疾病和衰老过程中。我们提出，与来自年轻供者的淋巴细胞相比，来自老年人外周血的CD4+ T辅助细胞和克隆，在没有任何细胞因子外源性影响的情况下，可能更容易发生嗜T细胞性HIV-1感染。临床免疫学部分将尝试直接检查这个问题。该计划的目标是进一步确定来自年轻和老年供体的T细胞以及人类Th1和Th2克隆的T细胞中T细胞、单核细胞和双向性HIV-1复制的差异。利用各种细胞因子（如IgF1、IL-4）和信号抑制剂（如caspase和激酶抑制剂）来抑制HIV-1感染，将进一步研究T细胞对HIV-1感染的易感性与细胞凋亡之间的关系。最后，我们将研究HIV-1及其糖蛋白对病毒相互作用和T淋巴细胞感染性的信号和基因表达要求。- HIV，趋化因子，老年，T细胞，Th1, Th2，共受体

The preferential replication of HIV in Th2 and Th0 cells over Th1 cells has been recently proposed to occur during the development of AIDS. To address this question, we have infected human T helper (Th) clones, developed from different normal donors, with different HIV isolates and examined all differences in HIV fusion, entry, and infectivity. Our studies has demonstrated that human T cells and antigen-specific T cell clones express significant levels of several chemokine receptors on their surface which mediate T-cell trafficking, degranulation, and intracellular calcium mobilization as well as serving as co-receptors mediating HIV-1 entry into these cell populations. However, despite these differences in chemokine receptor expression, our studies have demonstrated that human Th0, Th1, and Th2 clones are all capable of being infected with the various T-, M-, and dual-tropic HIV-1 strains. HIV-1-infected Th1 clones exhibit a rapid (1-5 day) Fas-mediated apoptosis in vitro compared to infected Th2 clones (4-21 days). The increased expression of Fas ligand on the surface of Th1 but not Th2 clones post HIV-1 infection may possibly explain the more rapid turnover of this CD4+ T cell subset. Further examination of the various apoptotic-signaling differences between human Th1 and Th2 clones revealed that the majority of human Th1 but not Th2 cells are susceptible to activation-induced cell death (AICD). In addition, the majority of human Th1 clones expressed little to no bcl-2 and bcl-xl (anti-apoptotic proteins) making them more susceptible to various apoptotic stimuli as well as HIV-1-mediated cell death. In contrast, human Th2 clones express higher levels of bcl-2 and bcl-xl and were found to be less susceptible to apoptosis and HIV-1-mediated cytopathic effects. Thus, the protection of bcl-expressing T cells from HIV- induced cell death suggests that apoptosis not only contributes to cell killing by HIV infection but may also permit the selective destruction of Th1 cells in the periphery leading to an increase in circulating Th2-like lymphocytes. This increased susceptibility of Th1 clones to HIV-mediated cell death suggests a major mechanism for HIV-induced immunosuppression in AIDS. Our findings that Th1 and Th2 clones also differ in the expression of certain cell surface chemokine receptor may account for the increased susceptibility of Th subsets. We believe that a Th0-Th1 to Th2 switch occurs during many chronic inflammatory disease as well as aging. We propose that CD4+ T helper cells and clones, without any exogenous influence from cytokines, derived from the peripheral blood of older individuals may be more permissive to T cell tropic HIV-1 infections compared to lymphocytes derived from younger donors. The Clinical Immunology Section will attempt to directly examine this question. The objective of the proposed project is to further define the differences in T cell-, monocyte-, and dual-tropic HIV-1 replication in T cells derived from young and old donors as well as in human Th1 and Th2 clones. The relationship between T cell susceptibility to HIV-1 infectivity and apoptosis will be further examined using various cytokines (i.e. IgF1, IL-4) and signaling inhibitor agents (ie caspase and kinase inhibitors) to hinder HIV-1 infectivity. Finally, we will examine the signaling and gene expression requirements of HIV-1 and its glycoproteins for virus interactions and infectivity of T lymphocytes. - HIV, Chemokines, Elderly, T cells, Th1, Th2, Co-Receptors