Role Of Innate Immunity In The Initiation And Pathogenes

先天免疫在起始和病原体中的作用

• 批准号: 6986990
• 负责人: Anthony S. Fauci
• 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/6986990
• 关键词: CD95 molecule; HIV infections; apoptosis; biological signal transduction; cell proliferation; chemokine; chemokine receptor; enzyme linked immunosorbent assay; flow cytometry; gene induction /repression; host organism interaction; human immunodeficiency virus; human tissue; immunomagnetic separation; interferons; lectin; microarray technology; microorganism culture; microorganism immunology; natural killer cells; pathologic process; receptor expression; virus envelope; virus infection mechanism; virus load

Innate immunity is the first line of defense designed to protect the host from invading pathogens, including HIV. We have previously demonstrated that suppression of natural killer (NK) cell function can be profound and that it is related to the stage of HIV infection as well as the level of HIV plasma viremia. Our study revealed that HIV viremia impairs the ability of NK cells to secrete CC-chemokines and alters the expression of various inhibitory and chemokine receptors expressed on NK cells. Further analysis of NK-cell specific surface receptors revealed upregulation of inhibitory NK receptors and chemokine receptor CCR5. In addition, our data showed CCR5 upregulation to be induced as a result of immune activation while induction of iNKRs appeared to be a direct result of an HIV-induced effect. Analysis of NK cell interactions with R5 and X4 HIV envelopes showed profound suppression of generic NK cell function upon exposure to these envelopes. Furthermore, DNA microarray analyses of NK cells in the presence and absence of HIV envelopes delineated upregulation of several genes that were important in inducing apoptosis and suppression of cell proliferation. Similarly, exposure to HIV envelopes suppressed the expression of several genes critical for cell proliferation and generic NK cell function. Functional studies confirmed the profound suppresssive ability of HIV envelopes on generic NK cell functions such as cytotoxicity, proliferation, and secretion of cytokines and chemokines. Future studies will be focused on delineating the underlying mechanisms involved in the interaction between R5 and X4 HIV envelopes and NK cells. Further studies will address the cellular and molecular basis for this HIV envelope-induced suppressive effect on NK cells. Specific roles of NK cell receptors, particularly those belonging to the C-type lectin family will be investigated as potential igands for HIV envelopes. DNA microarray analyses of NK cells from HIV viremic patients showed upregulation of genes induced by interferon when compared with those from HIV aviremic individuals and HIV seronegative normal volunteers. Analyses of these gene clusters have lead us to identify pathways of signal transduction that are abnormally regulated in HIV viremic state. We have further demonstrated that NK cells from HIV viremic patients express relatively higher levels of fas molecule on their surface and are susceptible to fas-mediated apoptosis upon exposure to sFASL. In addition, NK cells from HIV viremic individuals have reduced surface expresssion of interleukin receptors and express significantly higher levels of intracellular Ki67, indicating a higher level of cellular activation associated with the HIV viremic state. We have further demonstrated that HIV-infected individuals have elevated levels of sfas and SFASL circulating in the serum during viremia when compared to the levels of these molecules during the aviremic state. These observations indicate a profound effect of HIV viremic state on the ability of NK cells to proliferate, undergo chemotaxis, and ultimately to survive in vivo. Future experiments will be focused on evaluating the turnover of NK cells in vivo after administration of BRDU. Such experiments will help us to understand the nature of NK cell proliferation and turnover in the HIV viremic state.

先天免疫是保护宿主免受包括艾滋病毒在内的病原体入侵的第一道防线。我们以前已经证明，自然杀伤（NK）细胞功能的抑制可能是深刻的，它与艾滋病毒感染的阶段以及艾滋病毒血浆病毒血症的水平。我们的研究表明，HIV病毒血症损害NK细胞分泌CC-趋化因子的能力，并改变NK细胞上表达的各种抑制性和趋化因子受体的表达。NK细胞特异性表面受体的进一步分析揭示了抑制性NK受体和趋化因子受体CCR 5的上调。此外，我们的数据显示，免疫激活诱导CCR 5上调，而iNKRs的诱导似乎是HIV诱导效应的直接结果。NK细胞与R5和X4 HIV包膜相互作用的分析显示，暴露于这些包膜后，一般NK细胞功能受到严重抑制。此外，在存在和不存在HIV包膜的情况下，NK细胞的DNA微阵列分析描绘了在诱导细胞凋亡和抑制细胞增殖中重要的几个基因的上调。同样，暴露于HIV包膜抑制了对细胞增殖和一般NK细胞功能至关重要的几个基因的表达。功能研究证实了HIV包膜对一般NK细胞功能如细胞毒性、增殖和细胞因子和趋化因子分泌的深刻抑制能力。未来的研究将集中在描绘R5和X4 HIV包膜和NK细胞之间相互作用的潜在机制。进一步的研究将解决这种HIV病毒诱导的NK细胞抑制作用的细胞和分子基础。NK细胞受体的具体作用，特别是那些属于C型凝集素家族将被调查作为HIV包膜的潜在配体。 HIV病毒血症患者NK细胞的DNA微阵列分析显示，与HIV病毒血症个体和HIV血清阴性正常志愿者相比，干扰素诱导的基因上调。对这些基因簇的分析使我们确定了在HIV病毒血症状态下受到异常调节的信号转导途径。我们进一步证明了来自HIV病毒血症患者的NK细胞在其表面上表达相对较高水平的Fas分子，并且在暴露于sFASL时对Fas介导的细胞凋亡敏感。此外，来自HIV病毒血症个体的NK细胞具有减少的白细胞介素受体的表面表达，并且表达显著更高水平的细胞内Ki 67，表明与HIV病毒血症状态相关的更高水平的细胞活化。我们已经进一步证明，HIV感染者在病毒血症期间血清中循环的sfas和SFASL水平升高，与这些分子在病毒血症状态期间的水平相比。这些观察结果表明，HIV病毒血症状态对NK细胞增殖、进行趋化性和最终在体内存活的能力具有深远的影响。未来的实验将集中在评估BRDU给药后体内NK细胞的周转。这些实验将帮助我们了解HIV病毒血症状态下NK细胞增殖和周转的性质。