Switch from homeostatic to inflammatory cytokines by NK/ILC in HIV-infected gut

 描述（由申请方提供）：肠道上皮屏障完整性的破坏是HIV感染期间肠道和全身炎症的主要相关因素，其允许微生物易位（MT）穿过肠道细胞屏障。解释HIV感染期间MT增加的一种理论是上皮紧密连接的破坏，这反过来又允许管腔细菌和细菌抗原增加粘膜渗透到肠道固有层中，然后进入体循环，导致炎症。MT在cART后仍然存在，即使在发生显著病毒抑制的HIV感染者中也是如此。细胞因子干扰素-γ（IFN）增加胃肠道（GI）道上皮屏障通透性。IFN-γ的来源是令人困惑的，特别是考虑到在疾病的早期，感染的患者已经严重耗尽肠道CD 4 + T细胞，包括Th 1细胞。此外，肠道CD 4 + T细胞恢复相对缓慢，因此它们对IFN的贡献可能最小。虽然HIV特异性CD 8 + T细胞在HIV感染期间提供IFN的来源，但它们对HIV抗原的反应在cART期间受到抑制。IFN的另一个主要来源是先天淋巴细胞：自然杀伤细胞（NK）和先天淋巴细胞（ILC）。我们的初步数据表明，有更高的频率的肠道来源的NK/ILC（包括那些表达NK活化受体，NKp 44），产生IFN时，他们从病毒血症的HIV感染的个人相比，从未感染的个人的胃肠道获得的细胞。我们假设HIV创造了一种环境，改变了NK/ILC的功能，从维持胃肠道内稳态的重要细胞到导致感染患者肠道炎症增加和屏障功能障碍的细胞。我们假设HIV通过以下方式直接和间接诱导炎性NK/ILC：1）刺激肠髓样树突细胞（mDC）分泌促炎细胞因子; 2）修饰肠道微生物组以增加致病菌，3）诱导CD 4 + T细胞上NKp 44的配体的表达，其触发ILC 3（其通常分泌IL-22）以开始分泌IFN和肿瘤坏死因子α（TNF α），和4）诱导HIV感染的T细胞上的配体表达，这又触发促炎性NK/ILC 1分泌IFN/TNF α。为了解决这些假设，我们提出以下几点：具体目标1：确定HIV和HIV改变的粘膜细菌（HAMB）有助于诱导结肠炎性ILC 3的机制。具体目标2：确定HIV和HAMB导致促炎性肠道NK 1/ILC 1频率增加的机制。具体目标3：评价未经治疗和经治疗的HIV感染期间肠道NK/ ILC细胞因子谱、NK/ILC活化受体配体表达、上皮屏障功能和炎症之间的关系。

 DESCRIPTION (provided by applicant): Disruption of gut epithelial barrier integrity is a major factor associated with gut and systemic inflammation during HIV infection by allowing microbial translocation (MT) across the intestinal cell barrier. One theory to explain increased MT during HIV infection is the disruption of epithelial tight junctions, which, in turn, allows increased mucosal penetration by luminal bacteria and bacterial antigens into the lamina propria of the gut and then into the systemic circulation resulting in inflammation. MT remains after cART, even in HIV-infected individuals in which significant virus suppression occurs. The cytokine interferon-gamma (IFN) increases gastrointestinal (GI) tract epithelial barrier permeability. The source of IFN- is puzzling especially given that early in the disease, infected patients have severely depleted intestinal CD4+ T-cells, including Th1 cells. Moreover, intestinal CD4+ T-cell recovery is relatively slow, so their contributions to IFN may be minimal at best. Although HIV-specific CD8+ T-cells provide a source of IFN during HIV infection, their response to HIV antigen is dampened during cART. Another major source of IFN is innate lymphocytes: natural killer cells (NK) and innate lymphoid cells (ILCs). Our preliminary data indicate that that there are higher frequencies of gut-derived NK/ILCs (including those that express the NK activation receptor, NKp44) that produce IFN when they were obtained from viremic HIV-infected individuals as compared to cells obtained from the GI tract of uninfected individuals. We hypothesize that HIV creates an environment that alters the function of NK/ILCs from cells that are important in maintaining homeostasis in the GI tract to cells that contribute to increased inflammation and barrier dysfunction in the gut of infected patients. We postulate that HIV both directly and indirectly induces inflammatory NK/ILC by 1) stimulating intestinal myeloid dendritic cells (mDC) to secrete pro- inflammatory cytokines 2) modifying the gut microbiome to increase pathobiont bacteria, which in turn trigger mDCs to secrete higher levels of pro-inflammatory cytokines 3) inducing the expression of ligands to NKp44 on CD4+ T-cells which trigger ILC3s (which normally secrete IL-22) to begin secreting IFN and tumor necrosis factor alpha (TNFa) and 4) inducing the expression of ligands on HIV-infected T-cells, which in turn, trigger pro-inflammatory NK/ILC1s to secrete IFN/TNFa. To address these hypotheses, we propose the following: Specific Aim 1: To determine the mechanism in which HIV and HIV-altered mucosal bacteria (HAMB) contribute to the induction of colonic inflammatory ILC3s. Specific Aim 2: To determine the mechanism in which HIV and HAMB contribute to increased frequencies of pro-inflammatory gut NK1/ILC1s. Specific Aim 3: To evaluate the relationship between gut NK/ ILC cytokine profiles, expression of NK/ILC activating receptor ligands, epithelial barrier function, and inflammation during untreated and treated HIV infection.