Incorporating the Cluster A and V1V2 Targets into a Minimal Structural Unit of the HIV-1 Envelope to Elicit a Cross-Clade Response with Potent Fc-Effector Functions

Plasma Human Immunodeficiency Virus 1 Soluble Glycoprotein 120 Association With Correlates of Immune Dysfunction and Inflammation in Antiretroviral Therapy-Treated Individuals With Undetectable Viremia

BACKGROUND

Chronic inflammation persists in some people living with human immunodeficiency virus (HIV) during antiretroviral therapy and is associated with premature aging. The glycoprotein 120 (gp120) subunit of HIV-1 envelope sheds and can be detected in plasma, showing immunomodulatory properties even in the absence of detectable viremia. We evaluated whether plasma soluble gp120 (sgp120) and a family of gp120-specific anti-cluster A antibodies, linked to CD4 depletion in vitro, contribute to chronic inflammation, immune dysfunction, and subclinical cardiovascular disease in participants of the Canadian HIV and Aging Cohort Study with undetectable viremia.

METHODS

Cross-sectional assessment of sgp120 and anti-cluster A antibodies was performed in 386 individuals from the cohort. Their association with proinflammatory cytokines and subclinical coronary artery disease was assessed using linear regression models.

RESULTS

High levels of sgp120 and anti-cluster A antibodies were inversely correlated with CD4+ T cell count and CD4/CD8 ratio. The presence of sgp120 was associated with increased levels of interleukin 6. In participants with detectable atherosclerotic plaque and detectable sgp120, anti-cluster A antibodies and their combination with sgp120 levels correlated positively with the total volume of atherosclerotic plaques.

CONCLUSIONS

This study showed that sgp120 may act as a pan toxin causing immune dysfunction and sustained inflammation in a subset of people living with HIV, contributing to the development of premature comorbid conditions.

Characterization of antibody-dependent cellular phagocytosis in patients infected with hepatitis C virus with different clinical outcomes

Early neutralizing antibodies against hepatitis C virus (HCV) and CD8 + T cell effector responses can lead to viral clearance. However, these functions alone are not sufficient to protect patients against HCV infection, thus undefined additional antiviral immune mechanisms are required. In recent years, Fc-receptor-dependent antibody effector functions, particularly, antibody-dependent cellular phagocytosis (ADCP) were shown to offer immune protection against several RNA viruses. However, its development and clinical role in patients with HCV infection remain unknown. In this study, we found that patients with chronic GT1a or GT3a HCV infection had significantly higher concentrations of anti-envelope 2 (E2) antibodies, predominantly IgG1 subclass, than patients that cleared the viruses while the latter had antibodies with higher affinities. 97% of the patients with HCV had measurable ADCP of whom patients with chronic disease showed significantly higher ADCP than those who naturally cleared the virus. Epitope mapping studies showed that patients with antibodies that target antigenic domains on the HCV E2 protein that are known to associate with neutralization function are also strongly associated with ADCP, suggesting antibodies with overlapping/dual functions. Correlation studies showed that ADCP significantly correlated with plasma anti-E2 antibody levels and neutralization function regardless of clinical outcome and genotype of infecting virus, while a significant correlation between ADCP and affinity was only evident in patients that cleared the virus. These results suggest ADCP was mostly driven by antibody titer in patients with chronic disease while maintained in clearers due to the quality (affinity) of their anti-E2 antibodies despite having lower antibody titers.

Plasmatic HIV-1 soluble gp120 is associated with immune dysfunction and inflammation in ART-treated individuals with undetectable viremia

Background

Chronic inflammation persists in some people living with HIV (PLWH), even during antiretroviral therapy (ART) and is associated with premature aging. The gp120 subunit of the HIV-1 envelope glycoprotein can shed from viral and cellular membranes and can be detected in plasma and tissues, showing immunomodulatory properties even in the absence of detectable viremia. We evaluated whether plasmatic soluble gp120 (sgp120) and a family of gp120-specific anti-cluster A antibodies, which were previously linked to CD4 depletion in vitro , could contribute to chronic inflammation, immune dysfunction, and sub-clinical cardiovascular disease in participants of the Canadian HIV and Aging cohort (CHACS) with undetectable viremia.

Methods

Cross-sectional assessment of plasmatic sgp120 and anti-cluster A antibodies was performed in 386 individuals from CHACS. Their association with pro-inflammatory cytokines, as well as subclinical coronary artery disease measured by computed tomography coronary angiography was assessed using linear regression models.

Results

In individuals with high levels of sgp120, anti-cluster A antibodies inversely correlated with CD4 count (p=0.042) and CD4:CD8 ratio (p=0.004). The presence of sgp120 was associated with increased plasma levels of IL-6. In participants with detectable atherosclerotic plaque and detectable sgp120, sgp120 levels, anti-cluster A antibodies and their combination correlated positively with the total volume of atherosclerotic plaques (p=0.01, 0.018 and 0.006, respectively).

Conclusion

Soluble gp120 may act as a pan toxin causing immune dysfunction and sustained inflammation in a subset of PLWH, contributing to the development of premature comorbidities. Whether drugs targeting sgp120 could mitigate HIV-associated comorbidities in PLWH with suppressed viremia warrants further studies.

Key points

Soluble gp120 is detected in the plasma of people living with HIV-1 with undetectable viremia. The presence of soluble gp120 and anti-cluster A antibodies is associated with immune dysfunction, chronic inflammation, and sub-clinical cardiovascular disease.

Engineered ACE2-Fc counters murine lethal SARS-CoV-2 infection through direct neutralization and Fc-effector activities

Soluble angiotensin-converting enzyme 2 (ACE2) constitutes an attractive antiviral capable of targeting a wide range of coronaviruses using ACE2 as their receptor. Using structure-guided approaches, we developed a series of bivalent ACE2-Fcs harboring functionally and structurally validated mutations that enhance severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor binding domain recognition by up to ~12-fold and remove angiotensin enzymatic activity. The lead variant M81 potently cross-neutralized SARS-CoV-2 variants of concern (VOCs), including Omicron, at subnanomolar half-maximal inhibitory concentration and was capable of robust Fc-effector functions, including antibody-dependent cellular cytotoxicity, phagocytosis, and complement deposition. When tested in a stringent K18-hACE2 mouse model, Fc-enhanced ACE2-Fc delayed death by 3 to 5 days or effectively resolved lethal SARS-CoV-2 infection in both prophylactic and therapeutic settings via the combined effects of neutralization and Fc-effector functions. These data add to the demonstrated utility of soluble ACE2 as a valuable SARS-CoV-2 antiviral and indicate that Fc-effector functions may constitute an important component of ACE2-Fc therapeutic activity.

Engineered ACE2-Fc counters murine lethal SARS-CoV-2 infection through direct neutralization and Fc-effector activities

Soluble Angiotensin-Converting Enzyme 2 (ACE2) constitutes an attractive antiviral capable of targeting a wide range of coronaviruses utilizing ACE2 as their receptor. Here, using structure-guided approaches, we developed divalent ACE2 molecules by grafting the extracellular ACE2-domain onto a human IgG1 or IgG3 (ACE2-Fc). These ACE2-Fcs harbor structurally validated mutations that enhance spike (S) binding and remove angiotensin enzymatic activity. The lead variant bound tightly to S, mediated in vitro neutralization of SARS-CoV-2 variants of concern (VOCs) with sub-nanomolar IC 50 and was capable of robust Fc-effector functions, including antibody-dependent-cellular cytotoxicity, phagocytosis and complement deposition. When tested in a stringent K18-hACE2 mouse model, it delayed death or effectively resolved lethal SARS-CoV-2 infection in a prophylactic or therapeutic setting utilizing the combined effect of neutralization and Fc-effector functions. These data confirm the utility of ACE2-Fcs as valuable agents in preventing and eliminating SARS-CoV-2 infection and demonstrate that ACE2-Fc therapeutic activity require Fc-effector functions.