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Fc-mediated effector function contributes to the in vivo antiviral effect of an HIV broadly neutralizing antibody.

ABSTRACT: Treatment of HIV infection with either anti-retroviral therapy (ART) or neutralizing monoclonal antibodies (NAbs) leads to a reduction in HIV plasma virus. Both ART and NAbs prevent new rounds of viral infection but NAbs may have the additional capacity to accelerate the loss of virus-infected cells through Fc gamma receptor (FcgR) mediated effector functions, which should affect the kinetics of plasma virus decline. Here we formally test this premise in vivo by comparing the plasma virus response to a single dose treatment with either unmodified NAb or those with either reduced or augmented Fc function. When infused into viremic SHIV-infected rhesus macaques, there was a 21% difference in slope of plasma virus decline between wt NAb and NAb with reduced Fc function. NAb engineered to increase FcgRIII binding and improve ADCC in vitro resulted in arming of effector cells in vivo yet led to viral decay kinetics similar to NAbs with reduced Fc function. These studies show that the predominant mechanism of antiviral activity of HIV NAbs is through inhibition of viral entry, but that Fc function does contribute to the overall antiviral activity, making them unique from standard ART. However, these data also show that increased FcgRIII engagement is insufficient to improve in vivo virus clearance.

ORGANISM(S): Macaca mulatta

PROVIDER: GSE136938 | GEO | 2020/07/20

REPOSITORIES: GEO

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Project description:Therapeutic strategies that enhance anti-viral immunity and reduce the viral reservoir are critical to achieving durable remission of HIV. The co-inhibitory receptor programmed death-1 (PD-1) regulates CD8+ T cell dysfunction during chronic HIV and SIV infections 1-4. In addition, PD-1+ CD4+ T cells constitute a significant fraction of the HIV/SIV viral reservoir5-7. We previously demonstrated that in vivo blockade of PD-1 during chronic SIV infection improves the function of anti-viral CD8+ T cells and B cells 4,8. However, the immunological effects of PD-1 blockade during anti-retroviral therapy (ART) and the potential to destabilize the persistent HIV/SIV reservoir have not been studied. Here, we show that administration of anti-PD-1 antibody (PD-1 Ab) 10 days prior to initiation of ART rapidly enhanced anti-viral CD8+ T cell function and diminished interferon stimulated genes (ISGs) that resulted in markedly improved viral suppression in plasma and better Th17 cell reconstitution in the rectal mucosa following ART initiation. In addition, PD-1 blockade during suppressive ART resulted in transient increases in plasma viremia, induction of gene signatures associated with effector CD8+ T cell function and ISGs, and lower levels of cell associated replication-competent virus suggesting destabilization of the viral reservoir. Following ART interruption, PD-1 Ab treated animals showed markedly higher expansion of proliferating CXCR5+ Perforin+ Granzyme B+ effector CD8+ T cells and lower regulatory T cells that resulted in delayed viral rebound and better control of viremia. PD-1 blockade administered only during suppressive ART however was only partially effective. Our results indicate an optimal regimen of PD-1 blockade administered in combination with ART, that augments anti-viral CD8+ T cell function and reduces the viral reservoir leading to improved control of viral rebound after ART interruption. These results have important implications for developing novel therapeutic interventions to achieve durable remission of HIV.

Project description:Background. HIV-infected individuals on antiretroviral therapy (HIV/ART) experience higher levels of non-AIDS morbidity than uninfected people, which is believed to be driven by inflammation that persists despite viral suppression. Elevations in plasma cytokines, coagulation markers and both innate and adaptive immune cell activation during untreated infection are often incompletely reversed by ART and associated with these morbidities. Monocytes/macrophages play a central role in many of these complications including neurocognitive and cardiovascular disease. Results. We investigated monocyte surface markers, gene expression and plasma cytokines in 11 HIV-infected older individuals (median age 53 years) who started therapy with low CD4 counts (median 129 cells/ul), with elevated hsCRP (≥2mg/L) despite long-term ART (median 7.4 years), along with age, gender, race and smoking status-matched controls. Major monocyte subsets (based on CD14/CD16/CD163) were not different from controls, but surface levels differed for CD163 (p=0.022), PD1 (p=0.015) and a trend for tissue factor (p=0.098). As a group, HIV/ART subjects had elevated levels of plasma CCL2 (MCP-1; p=0.0001), CXCL9 (MIG; p=0.04) and sIL2R (p=0.015), which were highly correlated, whereas sCD14 and several other markers were not significantly elevated. However, principal component analysis of soluble markers revealed that about half of HIV/ART subjects clustered with controls, whereas the remainder were distinct, driven by IL-10, CCL11, CXCL10, CXCL11 as well as CCL2, CXCL9 and sIL2R. Outlier subjects were significantly older than those who clustered with controls. Gene expression analysis unexpectedly revealed downregulation in HIV/ART monocytes of multiple genes linked to immune functions including inflammation, immune cell development and cell-cell signaling. Conclusions. These results reveal a novel pattern of immune dysregulation involving both aberrant inflammation and monocyte dysfunction, which suggests complex mechanisms linking monocytes and HIV/ART comorbidities.

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Fc-mediated effector function contributes to the in vivo antiviral effect of an HIV broadly neutralizing antibody.

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