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HIV-infected macrophages resist efficient NK cell-mediated killing while preserving inflammatory cytokine responses.

ABSTRACT: Natural killer (NK) cells are innate cytolytic effectors that target HIV-infected CD4⁺ T cells. In conjunction with antibodies recognizing the HIV envelope, NK cells also eliminate HIV-infected targets through antibody-dependent cellular cytotoxicity (ADCC). However, how these NK cell functions impact infected macrophages is less understood. We show that HIV-infected macrophages resist NK cell-mediated killing. Compared with HIV-infected CD4⁺ T cells, initial innate NK cell interactions with HIV-infected macrophages skew the response toward cytokine production, rather than release of cytolytic contents, causing inefficient elimination of infected macrophages. Studies with chimeric antigen receptor (CAR) T cells demonstrate that the viral envelope is equally accessible on CD4⁺ T cells and macrophages. Nonetheless, ADCC against macrophages is muted compared with ADCC against CD4⁺ T cells. Thus, HIV-infected macrophages employ mechanisms to evade immediate cytolytic NK cell function while preserving inflammatory cytokine responses. These findings emphasize the importance of eliminating infected macrophages for HIV cure efforts.

SUBMITTER: Clayton KL

PROVIDER: S-EPMC8486985 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature

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HIV-infected macrophages resist efficient NK cell-mediated killing while preserving inflammatory cytokine responses.

Clayton Kiera L KL Mylvaganam Geetha G Villasmil-Ocando Alonso A Stuart Heather H Maus Marcela V MV Rashidian Mohammad M Ploegh Hidde L HL Walker Bruce D BD

Cell host & microbe 20210210 3

Natural killer (NK) cells are innate cytolytic effectors that target HIV-infected CD4<sup>+</sup> T cells. In conjunction with antibodies recognizing the HIV envelope, NK cells also eliminate HIV-infected targets through antibody-dependent cellular cytotoxicity (ADCC). However, how these NK cell functions impact infected macrophages is less understood. We show that HIV-infected macrophages resist NK cell-mediated killing. Compared with HIV-infected CD4<sup>+</sup> T cells, initial innate NK cell ...[more]

PMID: 33571449

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Project description:Severe fever with thrombocytopenia syndrome virus (SFTSV), an emerging bunyavirus, causes severe fever with thrombocytopenia syndrome (SFTS), with a high fatality rate of 20%-30%. At present, however, the pathogenesis of SFTSV remains largely unclear and no specific therapeutics or vaccines against its infection are currently available. Therefore, animal models that can faithfully recapitulate human disease are important to help understand and treat SFTSV infection. Here, we infected seven Chinese rhesus macaques (Macaca mulatta) with SFTSV. Virological and immunological changes were monitored over 28 days post-infection. Results showed that mild symptoms appeared in the macaques, including slight fever, thrombocytopenia, leukocytopenia, increased aspartate aminotransferase (AST) and creatine kinase (CK) in the blood. Viral replication was persistently detectable in lymphoid tissues and bone marrow even after viremia disappeared. Immunocyte detection showed that the number of T cells (mainly CD8+ T cells), B cells, natural killer (NK) cells, and monocytes decreased during infection. In detail, effector memory CD8+ T cells declined but showed increased activation, while both the number and activation of effector memory CD4+ T cells increased significantly. Furthermore, activated memory B cells decreased, while CD80+/CD86+ B cells and resting memory B cells (CD27+CD21+) increased significantly. Intermediate monocytes (CD14+CD16+) increased, while myeloid dendritic cells (mDCs) rather than plasmacytoid dendritic cells (pDCs) markedly declined during early infection. Cytokines, including interleukin-6 (IL-6), interferon-inducible protein-10 (IP-10), and macrophage inflammatory protein 1 (MCP-1), were substantially elevated in blood and were correlated with activated CD4+ T cells, B cells, CD16+CD56+ NK cells, CD14+CD16+ monocytes during infection. Thus, this study demonstrates that Chinese rhesus macaques infected with SFTSV resemble mild clinical symptoms of human SFTS and provides detailed virological and immunological parameters in macaques for understanding the pathogenesis of SFTSV infection.

Project description:BackgroundAlpha-momorcharin (α-MMC) is a natural medicine derived from bitter melon and has been found to exert immunomodulatory effects. Our previous study indicated that α-MMC can regulate cytokine release from monocytes, but it remains unknown about its regulatory effect on different types of cytokines, such as inflammatory cytokines or anti-inflammatory cytokines.MethodsLPS-induced M1-type macrophages model and IL-4-induced M2-type macrophages model were established, and the expression of proinflammatory cytokines and anti-inflammatory cytokines were assessed by ELISA after α-MMC was administered. Then, a LPS-induced acute pneumonia mouse model was established, the proinflammatory cytokines levels and inflammatory lesions in lung tissues were examined by ELISA or H&E staining. Furthermore, omics screening analysis and Western blotting verification were performed on TLR4 and JAK1-STAT6 signalling pathway-related proteins to elucidate the regulatory mechanism of α-MMC in those M1 macrophages and M2 macrophages.ResultsAt a noncytotoxic dose of 0.3 μg/mL, α-MMC significantly inhibited the LPS-induced expression of inflammatory cytokines, such as TNF-α, IL-1β, IL-6, IL-8, MIP-1α and MCP-1, by M1 macrophages in a time-dependent manner, but α-MMC did not inhibit the IL-4-induced synthesis of anti-inflammatory cytokines, such as IL-10, IL-1RA, EGF, VEGF, TGF-β and CCL22, by M2 macrophages. Moreover, α-MMC also inhibited inflammatory cytokine expression in an LPS-induced acute pneumonia mouse model and alleviated inflammation in lung tissues. Furthermore, omics screening and Western blotting analysis confirmed that α-MMC inhibited TAK1/p-TAK1 and subsequently blocked the downstream MAPK and NF-κB pathways, thus inhibiting the LPS-induced inflammatory cytokine expression.ConclusionOur results reveal that α-MMC inhibits proinflammatory cytokine expression by M1 macrophages but not anti-inflammatory cytokine expression by M2 macrophages. The efficacy of α-MMC in selectively inhibiting proinflammatory cytokine expression renders it particularly suitable for the treatment of severe inflammation and autoimmune diseases characterized by cytokine storms.

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HIV-infected macrophages resist efficient NK cell-mediated killing while preserving inflammatory cytokine responses.

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HIV-infected macrophages resist efficient NK cell-mediated killing while preserving inflammatory cytokine responses.

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