Department of Infectious Diseases and Hospital Epidemiology, University of Zurich, University Hospital of Zurich, Zurich, Switzerland.
Front Immunol. 2024 Nov 7;15:1439328. doi: 10.3389/fimmu.2024.1439328. eCollection 2024.
Very little is known about the role of macrophages as immune mediators during natural HIV infection. Humanized mice are an extremely valuable model for studying HIV pathogenesis. However, the presence of murine mononuclear phagocytes in these models represents a significant limitation for studying their human counterpart. Therefore, we have developed a novel humanized mouse model that allows selective depletion of human myeloid cells at a time point of our choosing.
We genetically engineered human hematopoietic stem and progenitor cells (HSPCs) to express an inducible caspase-9 (iCas9) suicide system under a synthetic myeloid promoter. Using these HSPCs, we generated humanized mice. iCasp9 induction resulted in selective human myeloid cell death in this inducible human myeloid depletion (iHMD) mouse model. In addition, we co-cultured monocyte-derived macrophages with HIV-infected PBMCs to further mechanistically investigate the effect of macrophages on HIV replication using flow cytometry, cytokine analysis, and RNA sequencing of both macrophages and CD4+ T cells.
HIV infection induced a pro-inflammatory phenotype in HIV-infected humanized NSG mice during the early and late stages of HIV infection. Myeloid cell depletion in HIV-infected iHMD-NSG mice resulted in a rapid increase in HIV RNA replication, which was accompanied by a loss of pro-inflammatory cytokines. Co-culture of macrophages with HIV-infected PBMCs reproduced their anti-HIV effects observed . Transcriptomic data showed macrophages upregulate antiviral cytokines and chemokines in co-culture, while inducing CD4+ T cells to upregulate HIV restriction factors and downregulate pathways involved in protein expression and cell replication.
This study describes a novel role of macrophages as effector cells, both and , acting against HIV replication and limiting disease progression.
在自然感染 HIV 的过程中，巨噬细胞作为免疫介质的作用知之甚少。人源化小鼠是研究 HIV 发病机制的极其有价值的模型。然而，这些模型中存在的鼠单核吞噬细胞对研究其人类对应物构成了重大限制。因此，我们开发了一种新型的人源化小鼠模型，可在我们选择的时间点选择性耗尽人类髓样细胞。
我们通过基因工程使人类造血干细胞和祖细胞（HSPC）在合成的髓样启动子下表达诱导型 Caspase-9（iCas9）自杀系统。使用这些 HSPC，我们生成了人源化小鼠。iCasp9 诱导导致在这种可诱导的人髓样细胞耗竭（iHMD）小鼠模型中选择性地人髓样细胞死亡。此外，我们共培养单核细胞衍生的巨噬细胞与 HIV 感染的 PBMC，使用流式细胞术、细胞因子分析和巨噬细胞和 CD4+T 细胞的 RNA 测序进一步从机制上研究巨噬细胞对 HIV 复制的影响。
HIV 感染在 HIV 感染的 NSG 人源化小鼠的早期和晚期诱导了促炎表型。在 HIV 感染的 iHMD-NSG 小鼠中耗尽髓样细胞会导致 HIV RNA 复制迅速增加，伴随促炎细胞因子的丧失。将巨噬细胞与 HIV 感染的 PBMC 共培养可再现观察到的抗 HIV 作用。转录组数据显示，巨噬细胞在共培养中上调抗病毒细胞因子和趋化因子，同时诱导 CD4+T 细胞上调 HIV 限制因子并下调涉及蛋白表达和细胞复制的途径。
本研究描述了巨噬细胞作为效应细胞的新作用，既能直接作用于 HIV 复制，又能限制疾病进展。
