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Globally, human immunodeficiency virus type 1 (HIV-1) infection is a major health burden for which successful therapeutic options are still being investigated. Challenges facing current drugs that are part of the established life-long antiretroviral therapy (ART) include toxicity, development of drug resistant HIV-1 strains, the cost of treatment, and the inability to eradicate the provirus from infected cells. For these reasons, novel anti-HIV-1 therapeutics that can prevent or eliminate disease progression including the onset of the acquired immunodeficiency syndrome (AIDS) are needed. While development of HIV-1 vaccination has also been challenging, recent advancements demonstrate that infection of HIV-1-susceptible cells can be prevented in individuals living with HIV-1, by targeting C-C chemokine receptor type 5 (CCR5). CCR5 serves many functions in the human immune response and is a co-receptor utilized by HIV-1 for entry into immune cells. Therapeutics targeting CCR5 generally involve gene editing techniques including CRISPR, CCR5 blockade using antibodies or antagonists, or combinations of both. Here we review the efficacy of these approaches and discuss the potential of their use in the clinic as novel ART-independent therapies for HIV-1 infection.

A cure for HIV-1 remains unattainable as only one case has been reported, a decade ago 1 , 2 . The individual—who is known as the ‘Berlin patient’—underwent two allogeneic haematopoietic stem-cell transplantation (HSCT) procedures using a donor with a homozygous mutation in the HIV coreceptor CCR5 (CCR5Δ32/Δ32) to treat his acute myeloid leukaemia. Total body irradiation was given with each HSCT. Notably, it is unclear which treatment or patient parameters contributed to this case of long-term HIV remission. Here we show that HIV-1 remission may be possible with a less aggressive and toxic approach. An adult infected with HIV-1 underwent allogeneic HSCT for Hodgkin’s lymphoma using cells from a CCR5Δ32/Δ32 donor. He experienced mild gut graft-versus-host disease. Antiretroviral therapy was interrupted 16 months after transplantation. HIV-1 remission has been maintained over a further 18 months. Plasma HIV-1 RNA has been undetectable at less than one copy per millilitre along with undetectable HIV-1 DNA in peripheral CD4 T lymphocytes. Quantitative viral outgrowth assays from peripheral CD4 T lymphocytes show no reactivatable virus using a total of 24 million resting CD4 T cells. CCR5-tropic, but not CXCR4-tropic, viruses were identified in HIV-1 DNA from CD4 T cells of the patient before the transplant. CD4 T cells isolated from peripheral blood after transplantation did not express CCR5 and were susceptible only to CXCR4-tropic virus ex vivo. HIV-1 Gag-specific CD4 and CD8 T cell responses were lost after transplantation, whereas cytomegalovirus-specific responses were detectable. Similarly, HIV-1-specific antibodies and avidities fell to levels comparable to those in the Berlin patient following transplantation. Although at 18 months after the interruption of treatment it is premature to conclude that this patient has been cured, these data suggest that a single allogeneic HSCT with homozygous CCR5Δ32 donor cells may be sufficient to achieve HIV-1 remission with reduced intensity conditioning and no irradiation, and the findings provide further support for the development of HIV-1 remission strategies based on preventing CCR5 expression. An adult infected with HIV-1 who underwent allogeneic haematopoietic stem-cell transplantation for Hodgkin’s lymphoma using cells from a CCR5Δ32/Δ32 donor achieved full remission of HIV-1 for 18 months after transplantation and 16 months after cessation of antiretroviral therapy.

Background Post-stroke depression (PSD) is a significant impediment to successful rehabilitation and recovery after a stroke. Current therapeutic options are limited, leaving an unmet demand for specific and effective therapeutic options. Our objective was to investigate the safety of Maraviroc, a CCR5 antagonist, as a possible mechanism-based add-on therapeutic option for PSD in an open-label proof-of-concept clinical trial. Methods We conducted a 10-week clinical trial in which ten patients with subcortical and cortical stroke, suffering from PSD. were administered a daily oral dose of 300 mg Maraviroc. Participants were then monitored for an additional eight weeks. The primary outcome measure was serious treatment-emergent adverse events (TEAEs) and TEAEs leading to discontinuation. The secondary outcome measure was a change in the Montgomery-Asberg Depression Rating Scale (MADRS). Results Maraviroc was well tolerated, with no reports of serious adverse events or discontinuations due to intolerance. The MADRS scores substantially reduced from baseline to week 10 (mean change: -16.4 ± 9.3; p  < 0.001). By the conclusion of the treatment phase, a favorable response was observed in five patients, with four achieving remission. The time to response was relatively short, approximately three weeks. After the cessation of treatment, MADRS scores increased at week 18 by 6.1 ± 9.6 points ( p  = 0.014). Conclusions Our proof-of-concept study suggests that a daily dosage of 300 mg of Maraviroc may represent a well-tolerated and potentially effective pharmacological approach to treating PSD. Further comprehensive placebo-controlled studies are needed to assess the impact of Maraviroc augmentation on PSD. Trial registration ClinicalTrials.gov Identifier: NCT05932550, Retrospectively registered: 28/06/2023.

Microglia survey brain parenchyma, responding to injury and infections. Microglia also respond to systemic disease, but the role of blood–brain barrier (BBB) integrity in this process remains unclear. Using simultaneous in vivo imaging, we demonstrated that systemic inflammation induces CCR5-dependent migration of brain resident microglia to the cerebral vasculature. Vessel-associated microglia initially maintain BBB integrity via expression of the tight-junction protein Claudin-5 and make physical contact with endothelial cells. During sustained inflammation, microglia phagocytose astrocytic end-feet and impair BBB function. Our results show microglia play a dual role in maintaining BBB integrity with implications for elucidating how systemic immune-activation impacts neural functions. Although it is known that microglia respond to injury and systemic disease in the brain, it is unclear if they modulate blood–brain barrier (BBB) integrity, which is critical for regulating neuroinflammatory responses. Here authors demonstrate that microglia respond to inflammation by migrating towards and accumulating around cerebral vessels, where they initially maintain BBB integrity via expression of the tight-junction protein Claudin-5 before switching, during sustained inflammation, to phagocytically remove astrocytic end-feet resulting in impaired BBB function

The HIV co-receptors, CCR5 and CXCR4, are necessary for HIV entry into target cells, interacting with the HIV envelope protein, gp120, to initiate several signaling cascades thought to be important to the entry process. Co-receptor signaling may also promote the development of neuroHIV by contributing to both persistent neuroinflammation and indirect neurotoxicity. But despite the critical importance of CXCR4 and CCR5 signaling to HIV pathogenesis, there is only one therapeutic (the CCR5 inhibitor Maraviroc) that targets these receptors. Moreover, our understanding of co-receptor signaling in the specific context of neuroHIV is relatively poor. Research into co-receptor signaling has largely stalled in the past decade, possibly owing to the complexity of the signaling cascades and functions mediated by these receptors. Examining the many signaling pathways triggered by co-receptor activation has been challenging due to the lack of specific molecular tools targeting many of the proteins involved in these pathways and the wide array of model systems used across these experiments. Studies examining the impact of co-receptor signaling on HIV neuropathogenesis often show activation of multiple overlapping pathways by similar stimuli, leading to contradictory data on the effects of co-receptor activation. To address this, we will broadly review HIV infection and neuropathogenesis, examine different co-receptor mediated signaling pathways and functions, then discuss the HIV mediated signaling and the differences between activation induced by HIV and cognate ligands. We will assess the specific effects of co-receptor activation on neuropathogenesis, focusing on neuroinflammation. We will also explore how the use of substances of abuse, which are highly prevalent in people living with HIV, can exacerbate the neuropathogenic effects of co-receptor signaling. Finally, we will discuss the current state of therapeutics targeting co-receptors, highlighting challenges the field has faced and areas in which research into co-receptor signaling would yield the most therapeutic benefit in the context of HIV infection. This discussion will provide a comprehensive overview of what is known and what remains to be explored in regard to co-receptor signaling and HIV infection, and will emphasize the potential value of HIV co-receptors as a target for future therapeutic development.

The chemokine receptor CCR5 plays a vital role in immune surveillance and inflammation. However, molecular details that govern its endogenous chemokine recognition and receptor activation remain elusive. Here we report three cryo-electron microscopy structures of G i1 protein-coupled CCR5 in a ligand-free state and in complex with the chemokine MIP-1α or RANTES, as well as the crystal structure of MIP-1α-bound CCR5. These structures reveal distinct binding modes of the two chemokines and a specific accommodate pattern of the chemokine for the distal N terminus of CCR5. Together with functional data, the structures demonstrate that chemokine-induced rearrangement of toggle switch and plasticity of the receptor extracellular region are critical for receptor activation, while a conserved tryptophan residue in helix II acts as a trigger of receptor constitutive activation. The chemokine receptor CCR5 plays multiple roles in the immune system. Here, structures of G i1 protein-coupled CCR5 with or without a chemokine bound and of the CCR5- chemokine MIP-1 α complex offer insight into the distinct binding modes of the ligands and into the mechanism of CCR5 activation.

Multiple genome-wide studies have identified associations between outcome of human immunodeficiency virus (HIV) infection and polymorphisms in and around the gene encoding the HIV co-receptor CCR5, but the functional basis for the strongest of these associations, rs1015164A/G, is unknown. We found that rs1015164 marks variation in an activating transcription factor 1 binding site that controls expression of the antisense long noncoding RNA (lncRNA) CCR5AS. Knockdown or enhancement of CCR5AS expression resulted in a corresponding change in CCR5 expression on CD4 + T cells. CCR5AS interfered with interactions between the RNA-binding protein Raly and the CCR5 3′ untranslated region, protecting CCR5 messenger RNA from Raly-mediated degradation. Reduction in CCR5 expression through inhibition of CCR5AS diminished infection of CD4 + T cells with CCR5-tropic HIV in vitro. These data represent a rare determination of the functional importance of a genome-wide disease association where expression of a lncRNA affects HIV infection and disease progression. Multiple genetic variants have been identified that influence the outcome of HIV infection. Carrington and colleagues investigate the mechanism of one of the strongest variants, rs1015164, and show that it influences expression of a lncRNA controlling CCR5 expression.

Interactions between C-C chemokine receptor types 2 (CCR2) and 5 (CCR5) and their ligands, including CCL2 and CCL5, mediate fibrogenesis by promoting monocyte/macrophage recruitment and tissue infiltration, as well as hepatic stellate cell activation. Cenicriviroc (CVC) is an oral, dual CCR2/CCR5 antagonist with nanomolar potency against both receptors. CVC's anti-inflammatory and antifibrotic effects were evaluated in a range of preclinical models of inflammation and fibrosis. Monocyte/macrophage recruitment was assessed in vivo in a mouse model of thioglycollate-induced peritonitis. CCL2-induced chemotaxis was evaluated ex vivo on mouse monocytes. CVC's antifibrotic effects were evaluated in a thioacetamide-induced rat model of liver fibrosis and mouse models of diet-induced non-alcoholic steatohepatitis (NASH) and renal fibrosis. Study assessments included body and liver/kidney weight, liver function test, liver/kidney morphology and collagen deposition, fibrogenic gene and protein expression, and pharmacokinetic analyses. CVC significantly reduced monocyte/macrophage recruitment in vivo at doses ≥20 mg/kg/day (p < 0.05). At these doses, CVC showed antifibrotic effects, with significant reductions in collagen deposition (p < 0.05), and collagen type 1 protein and mRNA expression across the three animal models of fibrosis. In the NASH model, CVC significantly reduced the non-alcoholic fatty liver disease activity score (p < 0.05 vs. controls). CVC treatment had no notable effect on body or liver/kidney weight. CVC displayed potent anti-inflammatory and antifibrotic activity in a range of animal fibrosis models, supporting human testing for fibrotic diseases. Further experimental studies are needed to clarify the underlying mechanisms of CVC's antifibrotic effects. A Phase 2b study in adults with NASH and liver fibrosis is fully enrolled (CENTAUR Study 652-2-203; NCT02217475).

CCR5 is a member of the G-protein coupled receptor family that serves as an essential co-receptor for cellular entry of R5-tropic HIV-1, and is a validated target for therapeutics against HIV-1 infections. In the present study, we designed and synthesized a series of novel small CCR5 inhibitors and evaluated their antiviral activity. GRL-117C inhibited the replication of wild-type R5-HIV-1 with a sub-nanomolar IC 50 value. These derivatives retained activity against vicriviroc-resistant HIV-1s, but did not show activity against maraviroc (MVC)-resistant HIV-1. Structural modeling indicated that the binding of compounds to CCR5 occurs in the hydrophobic cavity of CCR5 under the second extracellular loop, and amino acids critical for their binding were almost similar with those of MVC, which explains viral cross-resistance with MVC. On the other hand, one derivative, GRL-10018C, less potent against HIV-1, but more potent in inhibiting CC-chemokine binding, occupied the upper region of the binding cavity with its bis -THF moiety, presumably causing greater steric hindrance with CC-chemokines. Recent studies have shown additional unique features of certain CCR5 inhibitors such as immunomodulating properties and HIV-1 latency reversal properties, and thus, continuous efforts in developing new CCR5 inhibitors with unique binding profiles is necessary.

CCR5 plays a central role in infectious disease, host defense, and cancer progression, thereby making it an ideal target for therapeutic development. Notably, CCR5 is the major HIV entry co-receptor, where its surface density correlates with HIV plasma viremia. The level of CCR5 receptor occupancy (RO) achieved by a CCR5-targeting therapeutic is therefore a critical predictor of its efficacy. However, current methods to measure CCR5 RO lack sensitivity, resulting in high background and overcalculation. Here, we report on two independent, flow cytometric methods of calculating CCR5 RO using the anti-CCR5 antibody, Leronlimab. We show that both methods led to comparable CCR5 RO values, with low background on untreated CCR5+CD4+ T cells and sensitive measurements of occupancy on both blood and tissue-resident CD4+ T cells that correlated longitudinally with plasma concentrations in Leronlimab-treated macaques. Using these assays, we found that Leronlimab stabilized cell surface CCR5, leading to an increase in the levels of circulating and tissue-resident CCR5+CD4+ T cells in vivo in Leronlimab-treated macaques. Weekly Leronlimab treatment in a chronically SIV-infected macaque led to increased CCR5+CD4+ T cells levels and fully suppressed plasma viremia, both concomitant with full CCR5 RO on peripheral blood CD4+ T cells, demonstrating that CCR5+CD4+ T cells were protected from viral replication by Leronlimab binding. Finally, we extended these results to Leronlimab-treated humans and found that weekly 700 mg Leronlimab led to complete CCR5 RO on peripheral blood CD4+ T cells and a statistically significant increase in CCR5+CD4+ T cells in peripheral blood. Collectively, these results establish two RO calculation methods for longitudinal monitoring of anti-CCR5 therapeutic antibody blockade efficacy in both macaques and humans, demonstrate that CCR5+CD4+ T cell levels temporarily increase with Leronlimab treatment, and facilitate future detailed investigations into the immunological impacts of CCR5 inhibition in multiple pathophysiological processes.