Temsavir blocks the immunomodulatory activities of HIV-1 soluble gp120

Investigating the combination of Temsavir and entry inhibitors on HIV replication: Synergistic and antagonistic effects observed against various R5-tropic envelopes

HIV is still a pandemic; antiretroviral therapeutics for preventing and treating HIV infection continue to present significant challenges. The demand for new drugs and effective treatments remains ongoing. Here, we investigated the effects of combining Temsavir with other HIV entry inhibitors, including CD4 mimetic BNM-III-170, T20 or enfuvirtide, Ibalizumab, and Maraviroc. Our results show that TMR demonstrates both synergistic and antagonistic activity when combined those other entry inhibitors, depending on the concentration and the specific envelope used. Results suggest that while low-dose combinations, especially using Temsavir and CD4 mimetic, exhibited antagonistic effects, Temsavir showed synergy at low and medium concentrations in combination with enfuvirtide, Ibalizumab, and Maraviroc. These results are promising for the potential of co-administrating antiretrovirals for HIV treatment and highlights the importance of developing advanced antiviral strategies. On the other hand, the variable responses against different R5-tropic envelopes underscore the complexity of designing universally effective combination antiviral therapies.

NK Count and Natural Cytotoxicity in Immune Nonresponders Versus Responders Living With HIV

Despite viral suppression with antiretroviral therapy, immune nonresponders (INR) among people living with HIV (PLWH) still have a higher risk of developing AIDS-related and non-AIDS-related complications. Our study aimed to investigate the phenotype and functions of Natural Killer (NK) cells in INR, to better understand underlying mechanisms of immune nonresponse. Our cross-sectional study included PLWH aged over 45 with an undetectable HIV viral load sustained for at least 2 years. Participant CD4+ T-cell counts exceeded 500 cells/mm3 for IR or below 350 cells/mm3 for INR. We characterized NK cell subsets, performed natural cytotoxicity and ADCC assays, and phenotyped NK cells before and after functional assays. Median CD4 levels were 247.5 (IQR, 208.8-286.3) cells/mm3 and 768.5 (IQR, 673.3-957.8) cells/mm3 in the INR (n = 20) and IR (n = 40), respectively. NK cell counts were lower in INR (p = 0.00066), but the percentages were similar between IR and INR. NKG2A was the only differentially expressed marker between groups, showing higher expression in INR. Additionally, NK cell natural cytotoxicity was elevated in the INR group. Multivariate analyses associated CD4 nadir and low NK cell count with immune nonresponse. Our results do not indicate a clear role for NK-mediated ADCC in immune nonresponse. We did not objectify an association between CD8 hyperactivation and INR.

α-Synuclein fibrils enhance HIV-1 infection of human T cells, macrophages and microglia

HIV-associated neurocognitive disorders (HAND) and viral reservoirs in the brain remain a significant challenge. Despite their importance, the mechanisms allowing HIV-1 entry and replication in the central nervous system (CNS) are poorly understood. Here, we show that α-synuclein and (to a lesser extent) Aβ fibrils associated with neurological diseases enhance HIV-1 entry and replication in human T cells, macrophages, and microglia. Additionally, an HIV-1 Env-derived amyloidogenic peptide accelerated amyloid formation by α-synuclein and Aβ peptides. Mechanistic studies show that α-synuclein and Aβ fibrils interact with HIV-1 particles and promote virion attachment and fusion with target cells. Despite an overall negative surface charge, these fibrils facilitate interactions between viral and cellular membranes. The enhancing effects of human brain extracts on HIV-1 infection correlated with their binding to Thioflavin T, a dye commonly used to stain amyloids. Our results suggest a detrimental interplay between HIV-1 and brain amyloids that may contribute to the development of neurodegenerative diseases.

CD4 downregulation precedes Env expression and protects HIV-1-infected cells from ADCC mediated by non-neutralizing antibodies

HIV-1 envelope glycoprotein (Env) conformation substantially impacts antibody-dependent cellular cytotoxicity (ADCC). Envs from primary HIV-1 isolates adopt a prefusion "closed" conformation, which is targeted by broadly neutralizing antibodies (bnAbs). CD4 binding drives Env into more "open" conformations, which are recognized by non-neutralizing Abs (nnAbs). To better understand Env-Ab and Env-CD4 interaction in CD4+ T cells infected with HIV-1, we simultaneously measured antibody binding and HIV-1 mRNA expression using multiparametric flow cytometry and RNA flow fluorescent in situ hybridization (FISH) techniques. We observed that env mRNA is almost exclusively expressed by HIV-1 productively infected cells that already downmodulated CD4. This suggests that CD4 downmodulation precedes env mRNA expression. Consequently, productively infected cells express "closed" Envs on their surface, which renders them resistant to nnAbs. Cells recognized by nnAbs were all env mRNA negative, indicating Ab binding through shed gp120 or virions attached to their surface. Consistent with these findings, treatment of HIV-1-infected humanized mice with the ADCC-mediating nnAb A32 failed to lower viral replication or reduce the size of the viral reservoir. These findings confirm the resistance of productively infected CD4+ T cells to nnAbs-mediated ADCC and question the rationale of immunotherapy approaches using this strategy.

IMPORTANCE

Antibody-dependent cellular cytotoxicity (ADCC) represents an effective immune response for clearing virally infected cells, making ADCC-mediating antibodies promising therapeutic candidates for HIV-1 cure strategies. Broadly neutralizing antibodies (bNAbs) target epitopes present on the native "closed" envelope glycoprotein (Env), while non-neutralizing antibodies (nnAbs) recognize epitopes exposed upon Env-CD4 interaction. Here, we provide evidence that env mRNA is predominantly expressed by productively infected cells that have already downmodulated cell-surface CD4. This indicates that CD4 downmodulation by HIV-1 precedes Env expression, making productively infected cells resistant to ADCC mediated by nnAbs but sensitive to those mediated by bnAbs. These findings offer critical insights for the development of immunotherapy-based strategies aimed at targeting and eliminating productively infected cells in people living with HIV.

New Therapies and Strategies to Curb HIV Infections with a Focus on Macrophages and Reservoirs

More than 80 million people worldwide have been infected with the human immunodeficiency virus (HIV). There are now approximately 39 million individuals living with HIV/acquired immunodeficiency syndrome (AIDS). Although treatments against HIV infection are available, AIDS remains a serious disease. Combination antiretroviral therapy (cART), also known as highly active antiretroviral therapy (HAART), consists of treatment with a combination of several antiretroviral drugs that block multiple stages in the virus replication cycle. However, the increasing usage of cART is inevitably associated with the emergence of HIV drug resistance. In addition, the development of persistent cellular reservoirs of latent HIV is a critical obstacle to viral eradication since viral rebound takes place once anti-retroviral therapy (ART) is interrupted. Thus, several efforts are being applied to new generations of drugs, vaccines and new types of cART. In this review, we summarize the antiviral therapies used for the treatment of HIV/AIDS, both as individual agents and as combination therapies, and highlight the role of both macrophages and HIV cellular reservoirs and the most recent clinical studies related to this disease.

Inflammatory Biomarker Reduction With Fostemsavir Over 96 Weeks in Heavily Treatment-Experienced Adults With Multidrug-Resistant HIV-1 in the BRIGHTE Study

Background

Fostemsavir, a first-in-class attachment inhibitor that binds to the viral envelope protein gp120, is approved for heavily treatment-experienced persons with HIV-1 with limited treatment options. We explored changes in immunologic and coagulopathy parameters in the BRIGHTE study: a phase 3 trial that evaluated fostemsavir plus optimized background therapy in heavily treatment-experienced adults with multidrug-resistant HIV-1.

Methods

CD4+ T-cell count, CD4+/CD8+ ratio, soluble CD14, soluble CD163, and D-dimer levels were measured through 96 weeks in participants with 1 or 2 fully active antiretroviral agents available at screening. No formal statistical analyses were performed.

Results

Among 272 participants, increases were observed from baseline to week 96 in CD4+ T-cell count (mean increase, +205 cells/mm3) and CD4+/CD8+ ratio (mean increase, +0.24). The proportion of observed participants with a CD4+/CD8+ ratio ≥0.45 increased from 9% (25/272) at baseline to 40% (85/213) at week 96. From baseline to week 96, we also observed trends toward decreases in the following (mean [SD] change): soluble CD14, -738.2 (981.8) µg/L; soluble CD163, -138.0 (193.4) µg/L; and D-dimer, -0.099 (0.521) mg/L fibrinogen-equivalent units. Decreases in biomarkers were generally observed among subgroups by baseline disease characteristics, virologic response, and CD4+ T-cell count.

Conclusions

These data suggest that heavily treatment-experienced persons with multidrug-resistant HIV-1 treated with fostemsavir + optimized background therapy may have improvements in immune parameters, including markers of monocyte activation and coagulopathy.

Clinical Trials Registration

NCT02362503 (ClinicalTrials.gov; https://clinicaltrials.gov/study/NCT02362503).

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.

Viral and host mediators of non-suppressible HIV-1 viremia

Non-suppressible HIV-1 viremia (NSV) is defined as persistent low-level viremia on antiretroviral therapy (ART) without evidence of ART non-adherence or significant drug resistance. Unraveling the mechanisms behind NSV would broaden our understanding of HIV-1 persistence. Here we analyzed plasma virus sequences in eight ART-treated individuals with NSV (88% male) and show that they are composed of large clones without evidence of viral evolution over time in those with longitudinal samples. We defined proviruses that match plasma HIV-1 RNA sequences as 'producer proviruses', and those that did not as 'non-producer proviruses'. Non-suppressible viremia arose from expanded clones of producer proviruses that were significantly larger than the genome-intact proviral reservoir of ART-suppressed individuals. Integration sites of producer proviruses were enriched in proximity to the activating H3K36me3 epigenetic mark. CD4+ T cells from participants with NSV demonstrated upregulation of anti-apoptotic genes and downregulation of pro-apoptotic and type I/II interferon-related pathways. Furthermore, participants with NSV showed significantly lower HIV-specific CD8+ T cell responses compared with untreated viremic controllers with similar viral loads. We identified potential critical host and viral mediators of NSV that may represent targets to disrupt HIV-1 persistence.

Soluble CD4 and low molecular weight CD4-mimetic compounds sensitize cells to be killed by anti-HIV cytotoxic immunoconjugates

IMPORTANCE

HIV infection can be effectively treated to prevent the development of AIDS, but it cannot be cured. We have attached poisons to anti-HIV antibodies to kill the infected cells that persist even after years of effective antiviral therapy. Here we show that the killing of infected cells can be markedly enhanced by the addition of soluble forms of the HIV receptor CD4 or by mimics of CD4.

Current drugs for HIV-1: from challenges to potential in HIV/AIDS

The human immunodeficiency virus (HIV) persists in latently infected CD4+T cells and integrates with the host genome until cell death. Acquired immunodeficiency syndrome (AIDS) is associated with HIV-1. Possibly, treating HIV/AIDS is an essential but challenging clinical goal. This review provides a detailed account of the types and mechanisms of monotherapy and combination therapy against HIV-1 and describes nanoparticle and hydrogel delivery systems. In particular, the recently developed capsid inhibitor (Lenacapavir) and the Ainuovirine/tenofovir disoproxil fumarate/lamivudine combination (ACC008) are described. It is interestingly to note that the lack of the multipass transmembrane proteins serine incorporator 3 (SERINC3) and the multipass transmembrane proteins serine incorporator 5 (SERINC5) may be one of the reasons for the enhanced infectivity of HIV-1. This discovery of SERINC3 and SERINC5 provides new ideas for HIV-1 medication development. Therefore, we believe that in treating AIDS, antiviral medications should be rationally selected for pre-exposure and post-exposure prophylaxis to avoid the emergence of drug resistance. Attention should be paid to the research and development of new drugs to predict HIV mutations as accurately as possible and to develop immune antibodies to provide multiple guarantees for the cure of AIDS.

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.

Temsavir Modulates HIV-1 Envelope Conformation by Decreasing Its Proteolytic Cleavage

HIV-1 envelope glycoproteins (Envs) mediate viral entry and represent a target of choice for small molecule inhibitors. One of them, temsavir (BMS-626529) prevents the interaction of the host cell receptor CD4 with Env by binding the pocket under the β20-β21 loop of the Env subunit gp120. Along with its capacity to prevent viral entry, temsavir stabilizes Env in its "closed" conformation. We recently reported that temsavir affects glycosylation, proteolytic processing, and overall conformation of Env. Here, we extend these results to a panel of primary Envs and infectious molecular clones (IMCs), where we observe a heterogeneous impact on Env cleavage and conformation. Our results suggest that the effect of temsavir on Env conformation is associated with its capacity to decrease Env processing. Indeed, we found that the effect of temsavir on Env processing affects the recognition of HIV-1-infected cells by broadly neutralizing antibodies and correlates with their capacity to mediate antibody-dependent cellular cytotoxicity (ADCC).