Biology subjects

Blish, C. A.

Publications and source records attributed to Blish, C. A..

40 records · Page 3Linked to original sources

bioRxiv2019

TIGIT is upregulated by HIV-1 infection and marks a highly functional adaptive and mature subset of natural killer cells

ObjectiveOur objective was to investigate the mechanisms that govern natural killer (NK) cell responses to HIV, with a focus on specific receptor-ligand interactions involved in HIV recognition by NK cells.\n\nDesign and MethodsWe first performed a mass cytometry-based screen of NK cell receptor expression patterns in healthy controls and HIV+ individuals. We then focused mechanistic studies on the expression and function of T cell immunoreceptor with Ig and ITIM domains (TIGIT).\n\nResultsThe mass cytometry screen revealed that TIGIT is upregulated on NK cells of untreated HIV+ women, but not in antiretroviral-treated women. TIGIT is an inhibitory receptor that is thought to mark exhausted NK cells; however, blocking TIGIT did not improve anti-HIV NK cell responses. In fact, the TIGIT ligands CD112 and CD155 were not upregulated on CD4+ T cells in vitro or in vivo, providing an explanation for the lack of benefit from TIGIT blockade. TIGIT expression marked a unique subset of NK cells that express significantly higher levels of NK cell activating receptors (DNAM-1, NTB-A, 2B4, CD2) and exhibit a mature/adaptive phenotype (CD57hi, NKG2Chi, LILRB1hi, FcR{gamma}lo, Syklo). Furthermore, TIGIT+ NK cells had increased responses to mock-infected and HIV-infected autologous CD4+ T cells, and to PMA/ionomycin, cytokine stimulation and the K562 cancer cell line.\n\nConclusionsTIGIT expression is increased on NK cells from untreated HIV+ individuals. Although TIGIT does not participate directly in NK cell recognition of HIV, it marks a population of mature/adaptive NK cells with increased functional responses.

immunology↗

bioRxiv2019

Enhancing natural killer cell function with gp41-targeting bispecific antibodies to combat HIV infection

Objective(s)To develop and evaluate the activity of bispecific antibodies (bsAbs) to enhance NK cell antibody-dependent cellular cytotoxicity (ADCC) against HIV-infected cells.\n\nDesignThese bsAbs are based on patient-derived antibodies targeting the conserved gp41 stump of HIV Env, and also incorporate a high affinity scFv targeting the activating receptor CD16 on NK cells. Overall, we expect the bsAbs to provide increased affinity and avidity over their corresponding monoclonal antibodies, allowing for improved ADCC activity against Env-expressing target cells.\n\nMethodsbsAbs and their corresponding mAbs were expressed in 293T cells and purified. The binding of bsAbs and mAbs to their intended targets was determined using Bio-Layer Interferometry, as well as flow cytometry-based binding assays on in vitro infected cells. The ability of these bsAbs to improve NK cell activity against HIV-infected cells was tested using in vitro co-culture assays, using flow cytometry and calcein release to analyze NK cell degranulation and target cell killing, respectively.\n\nResultsThe bsAbs bound gp41 with similar affinity to their corresponding mAbs, and had increased affinity for CD16. The bsAbs also bound to primary CD4 T cells infected in vitro with two different strains of HIV. In addition, the bsAbs induce increased NK cell degranulation and killing of autologous HIV-infected CD4 T cells.\n\nConclusionsThese bsAbs may provide a promising strategy to improve NK-mediated immune targeting of infected cells during HIV infection.

immunology↗

bioRxiv2019

HLA upregulation during dengue virus infection suppresses the natural killer cell response

Dengue virus (DENV) is the most prevalent mosquito-borne virus in the world and a major cause of morbidity in the tropics and subtropics. Upregulation of HLA class I molecules has long been considered a feature of DENV infection, yet this has not been evaluated in the setting of natural infection. Natural killer (NK) cells, an innate immune cell subset critical for mounting an early response to viral infection, are inhibited by self HLA class I, suggesting that upregulation of HLA class I during DENV infection could dampen the NK cell response. Here we addressed whether upregulation of HLA class I molecules occurs during in vivo DENV infection and, if so, whether this suppresses the NK cell response. We found that HLA class I expression was indeed upregulated during acute DENV infection across multiple cell lineages in vivo. To better understand the role of HLA class I upregulation, we infected primary human monocytes, a major target of DENV infection, in vitro. Upregulation of total HLA class I is dependent on active viral replication and is mediated in part by cytokines and other soluble factors induced by infection, while upregulation of HLA-E occurs in the presence of replication-incompetent virus. Importantly, blocking DENV-infected monocytes with a pan-HLA class I Fab nearly doubles the frequency of degranulating NK cells, while blocking HLA-E does not significantly improve the NK cell response. These findings demonstrate that upregulation of HLA class I during DENV infection suppresses the NK cell response, potentially contributing to disease pathogenesis.

immunology↗

bioRxiv2017

Strain-Specific Human Natural Killer Cell Recognition of Influenza A Virus

AbstractInnate Natural killer (NK) cells employ an array of surface receptors to detect altered self induced by infection or malignancy. Despite their decisive role in early antiviral immunity, the cellular mechanisms governing if or how they discriminate between viral infections remain unresolved. Here, we demonstrate that while human NK cells are capable of reducing infection levels of distinct influenza A strains, the A/California/07/2009 (pH1N1) strain induces a significantly more robust IFN-{gamma} response than A/Victoria/361/2011 (H3N2) and all other strains tested. This surprising degree of strain specificity results in part from the inability of the pH1N1 strain to downregulate the activating ligands CD112 (Nectin-2) and CD54 (ICAM-1) as efficiently as the H3N2 strain, leading to enhanced NK cell detection and IFN-{gamma} secretion. A network analysis of differentially expressed transcripts identifies the interferon /{beta} receptor (IFNAR) pathway as an additional, critical determinant of this strain-specific response. Strain-specific downregulation of NK cell activating ligands and modulation of type I IFN production represents a previously unrecognized influenza immunoevasion tactic and could present new opportunities to modulate the quality and quantity of the innate antiviral response for therapeutic benefit.\n\nOne Sentence SummaryHuman natural killer cells distinguish between Influenza A strains using a combinatorial cytokine priming and receptor-ligand signaling mechanism.

immunology↗