Advancing towards HIV-1 remission: Insights and innovations in stem cell therapies.

Human immunodeficiency virus type 1 (HIV-1) continues to pose a significant global health challenge despite advances in combined antiretroviral therapy (cART), which has transformed HIV-1 infection from a fatal disease to a manageable chronic condition. However, cART is not curative, and its long-term use is associated with challenges such as pill burden, drug toxicities, and the emergence of drug-resistant viral strains. The persistence of active viral reservoirs necessitates lifelong treatment, highlighting the need for alternative therapeutic strategies capable of achieving HIV-1 remission or cure. Stem cell therapy has emerged as a promising approach to address these challenges by targeting latent viral reservoirs, restoring host immune function, and potentially achieving sustained viral suppression in the absence of cART. This review critically evaluates current scientific literature on stem cell therapies for HIV-1, focusing on three major approaches: 1) hematopoietic stem cell transplantation (HSCT), 2) gene therapy, and 3) cell-based immunotherapies. Each approach is examined in terms of its underlying mechanisms, clinical feasibility, recent advancements, and associated challenges. Furthermore, future research directions are discussed, emphasizing the optimization of the current treatment protocols, enhancement of safety and efficacy, and the importance of large-scale clinical trials with different cohorts (different HIV clades, different genders of participants, and pediatric HIV) to evaluate long-term outcomes that include effective and scalable HIV cure challenges. Collaborative efforts across multidisciplinary fields are needed to overcome existing barriers so to realize the full therapeutic potential of stem cell-based approaches for developing an effective and scalable remission or cure strategies.

CCR5 Decorated Rilpivirine Lipid Nanoparticles Build Myeloid Drug Depots Which Sustains Antiretroviral Activities.

Antiretroviral therapy (ART) improves the quality of life for those living with the human immunodeficiency virus type one (HIV-1). However, poor compliance reduces ART effectiveness and leads to immune compromise, viral mutations, and disease co-morbidities. A novel drug formulation is made whereby a lipid nanoparticle (LNP) carrying rilpivirine (RPV) is decorated with the C-C chemokine receptor type 5 (CCR5). This facilitates myeloid drug depot deposition. Particle delivery to viral reservoirs is tracked by positron emission tomography. The CCR5-mediated RPV LNP cell uptake and retention reduce HIV-1 replication in human monocyte-derived macrophages and infected humanized mice. Focused ultrasound allows the decorated LNP to penetrate the blood-brain barrier and reach brain myeloid cells. These findings offer a role for CCR5-targeted therapeutics in antiretroviral delivery to optimize HIV suppression.

Inhibition of corrosion on API 5L X52 pipeline steel in acid media by Tradescantia spathacea.

The concentration effect of Tradescantia spathacea (T. spathacea) as corrosion inhibitor of API 5L X52 steel in 0.5 M of H2SO4 was studied here through electrochemical and gravimetric techniques. To achieve it, samples of the material were prepared to be submitted to each of the tests. Results from electrochemical impedance spectroscopy (EIS) showed that there was an optimum concentration of the inhibitor in which is reached the maximum inhibition efficiency, displaying the best inhibition characteristics for this system with a maximum inhibition of 89% by using 400 ppm. However, the efficiency decreased until 40% when the temperature was increased to 60°C. Potentiodynamic polarization curves (PDP) revealed that some of the present compounds of T. spathacea may affect anodic and cathodic process, so it can be classified as a mix-type corrosion inhibitor for API 5L X52 in sulfuric acid. Also, this compound followed an adsorption mechanism; this can be described through a Frumkin isotherm with an adsorption standard free energy difference (ΔG°) of -56.59 kJmol-1. Metal surface was studied through scanning electron microscope, results revealed that by adding inhibitor, the metal surface is protected; also, they evidenced low damages compared with the surface with no inhibitor. Finally, Tradescantia spathacea inhibited the corrosion process with 82% efficiency.

Genetic signatures in the highly virulent subtype B HIV-1 conferring immune escape to V1/V2 and V3 broadly neutralizing antibodies.

HIV-1 is considered to become less susceptible to existing neutralizing antibodies over time. Our study on the virulent B (VB) HIV-1 identified genetic signatures responsible for immune escape from broadly neutralizing antibodies (bNAbs) targeting V1/V2 and V3 glycan epitopes. We found that the absence of N295 and N332 glycans in the high mannose patch, which are crucial for neutralization by V3 glycan bNAbs and are typically conserved in subtype B HIV-1, is a notable feature in more than half of the VB variants. Neutralization assays confirmed that the loss of these two glycans in VB HIV-1 leads to escape from V3 glycan bNAbs. Additionally, all VB variants we investigated have an insertion in V2, contributing to immune escape from V1/V2 bNAbs PG9 and PG16. These findings suggest potential co-evolution of HIV-1 virulence and antigenicity, underscoring the need to monitor both the pathogenicity and neutralization susceptibility of newly emerged HIV-1 strains.

Replacement of Antiretroviral Therapy with HIV Broadly Neutralizing Antibodies to Maximize the Effectiveness of Chemotherapy in HIV Patients with Lung Cancer.

Non-small cell lung cancer (NSCLC) is the most fatal non-AIDS defining cancer in people living with HIV (PWH) on antiretroviral therapy (ART). Treatment of malignancies in PWH requires concomitant cancer therapy and ART, which can lead to potential drug-drug interactions (DDIs) and overlapping toxicities. In this study, we hypothesize that replacement of ART with HIV broadly neutralizing antibodies (bNAbs) during cancer chemotherapy (chemo) may maintain HIV suppression and tumor inhibition while minimizing DDIs and overlapping toxicities. We compared HIV suppression, tumor inhibition, and toxicity between conventional treatment (ART plus chemo) and a new modality (bNAbs plus chemo) in humanized mice. Humanized mice infected with HIVYU2 and xenografted with human NSCLC A549 cells were treated with NSCLC chemo (cisplatin and gemcitabine) and first-line ART (dolutegravir, tenofovir disoproxil difumarate, and emtricitabine) or bNAbs (N49P9.6-FR and PGT 121) at human equivalent drug doses. We monitored plasma HIV RNA, tumor volume, and toxicities over five cycles of chemo. We found that chemo plus ART or bNAbs were equally effective at maintaining suppression of HIV viremia and tumor growth. Comparative analysis showed that mice on ART and chemo had significant reductions in body weight and significant increases in plasma creatinine concentrations compared with mice on bNAbs and chemo, which suggests that a combination of bNAbs and chemo produces less renal toxicity than an ART and chemo combination. These data suggest that bNAb therapy during concomitant chemo may be an improved treatment option over ART for PWH and NSCLC, and possibly other cancers, because bNAbs maintain HIV suppression while minimizing DDIs and toxicities.

Humanized mouse models for preclinical evaluation of HIV cure strategies.

Although the world is currently focused on the COVID-19 pandemic, HIV/AIDS remains a significant threat to public health. To date, the HIV/AIDS pandemic has claimed the lives of over 36 million people, while nearly 38 million people are currently living with the virus. Despite the undeniable success of antiretroviral therapy (ART) in controlling HIV, the medications are not curative. Soon after initial infection, HIV integrates into the genome of infected cells as a provirus, primarily, within CD4+ T lymphocytes and tissue macrophages. When not actively transcribed, the provirus is referred to as a latent reservoir because it is hidden to the immune system and ART. Following ART discontinuation, HIV may emerge from the replication-competent proviruses and resumes the infection of healthy cells. Thus, these latent reservoirs are a major obstacle to an HIV cure, and their removal remains a priority. A vital aspect in the development of curative therapies is the demonstration of efficacy in an animal model, such as the humanized mouse model. Therefore, optimization, standardization, and validation of the humanized mouse model are a priority. The purpose of this review article is to provide an update on existing humanized mouse models, highlighting the advantages and disadvantages of each as they pertain to HIV cure studies and to review the approaches to curative therapies that are under investigation.

Human Hematopoietic Stem Cell (HSC)-Engrafted NSG Mice for HIV Latency Research.

Combination antiretroviral therapy (cART) suppresses HIV in most patients, but it cannot cure HIV infection. The main challenge to a cure is the presence of latent replication-competent HIV in resting CD4+ T cells in blood and tissues, which reignite infection after cART removal. The long half-life of this reservoir is a major barrier to a cure, and its elimination is a main goal of current HIV research. Animal models that recapitulate HIV latency can provide key insights into the establishment of HIV latency and, more importantly, enable the testing of HIV eradication strategies. We describe a protocol for the generation of humanized mice by intrahepatic injection of human cord blood-derived CD34+ hematopoietic stem cells (HSC) into newborn NSG mice, the HSC-NSG mouse model. We also describe a protocol for establishing HIV latency in this model. HSC-NSG mice have provided proof-of-concept for an approach combining HIV gene editing and HIV suppression in tissues that may cure HIV in infected humans.

Combined cART including Tenofovir Disoproxil, Emtricitabine, and Dolutegravir has potent therapeutic effects in HIV-1 infected humanized mice.

HIV-1 reservoirs persist in the presence of combined antiretroviral therapy (cART). However, cART has transformed HIV-1 infection into a chronic disease marked by control of HIV-1 viral load and mortality reduction. Major challenges remain, including viral resistance upon termination of cART and persistence and identification of tissue distribution of HIV-1 reservoirs. Thus, appropriate animal models that best mimic HIV-1 pathogenesis are important, and the current study complements our previously published validation of the CD34+ hematopoietic humanized mouse model for this purpose. Here we analyze viral suppression using the recently developed combination of antiretrovirals that include Tenofovir Disoproxil (TDF), Emtricitabine (FTC), and Dolutegravir (DTG), a choice based on recent clinical outcomes showing its improved antiretroviral potency, CD4+ T cell preservation, tolerability, and prevention of viral drug resistance compared to that of previous regimens. We used quantitative Airyscan-based super resolution confocal microscopy of selected mouse tissues. Our data allowed us to identify specific solid tissue reservoirs of human T cells expressing the HIV-1 core protein p24. In particular, lymph node, brain, spleen, and liver were visualized as reservoirs for residual infected cells. Marked reduction of viral replication was evident. Considering that detection and visualization of cryptic sites of HIV-1 infection in tissues are clearly crucial steps towards HIV-1 eradication, appropriate animal models with pseudo-human immune systems are needed. In fact, current studies with humans and non-human primates have limited sample availability at multiple stages of infection and cannot easily analyze the effects of differently administered combined antiretroviral treatments on multiple tissues. That is easier to manage when working with humanized mouse models, although we realize the limitations due to low human cell recovery and thus the number of cells available for thorough and comprehensive analyses. Nonetheless, our data further confirm that the CD34+ humanized mouse model is a potentially useful pre-clinical model to study and improve current anti-HIV-1 therapies.

7,8-Dihydroxyflavone improves neuropathological changes in the brain of Tg26 mice, a model for HIV-associated neurocognitive disorder.

The combined antiretroviral therapy era has significantly increased the lifespan of people with HIV (PWH), turning a fatal disease to a chronic one. However, this lower but persistent level of HIV infection increases the susceptibility of HIV-associated neurocognitive disorder (HAND). Therefore, research is currently seeking improved treatment for this complication of HIV. In PWH, low levels of brain derived neurotrophic factor (BDNF) has been associated with worse neurocognitive impairment. Hence, BDNF administration has been gaining relevance as a possible adjunct therapy for HAND. However, systemic administration of BDNF is impractical because of poor pharmacological profile. Therefore, we investigated the neuroprotective effects of BDNF-mimicking 7,8 dihydroxyflavone (DHF), a bioactive high-affinity TrkB agonist, in the memory-involved hippocampus and brain cortex of Tg26 mice, a murine model for HAND. In these brain regions, we observed astrogliosis, increased expression of chemokine HIV-1 coreceptors CXCR4 and CCR5, neuroinflammation, and mitochondrial damage. Hippocampi and cortices of DHF treated mice exhibited a reversal of these pathological changes, suggesting the therapeutic potential of DHF in HAND. Moreover, our data indicates that DHF increases the phosphorylation of TrkB, providing new insights about the role of the TrkB-Akt-NFkB signaling pathway in mediating these pathological hallmarks. These findings guide future research as DHF shows promise as a TrkB agonist treatment for HAND patients in adjunction to the current antiviral therapies.

Low-Level Ionizing Radiation Induces Selective Killing of HIV-1-Infected Cells with Reversal of Cytokine Induction Using mTOR Inhibitors.

HIV-1 infects 39.5 million people worldwide, and cART is effective in preventing viral spread by reducing HIV-1 plasma viral loads to undetectable levels. However, viral reservoirs persist by mechanisms, including the inhibition of autophagy by HIV-1 proteins (i.e., Nef and Tat). HIV-1 reservoirs can be targeted by the "shock and kill" strategy, which utilizes latency-reversing agents (LRAs) to activate latent proviruses and immunotarget the virus-producing cells. Yet, limitations include reduced LRA permeability across anatomical barriers and immune hyper-activation. Ionizing radiation (IR) induces effective viral activation across anatomical barriers. Like other LRAs, IR may cause inflammation and modulate the secretion of extracellular vesicles (EVs). We and others have shown that cells may secrete cytokines and viral proteins in EVs and, therefore, LRAs may contribute to inflammatory EVs. In the present study, we mitigated the effects of IR-induced inflammatory EVs (i.e., TNF-α), through the use of mTOR inhibitors (mTORi; Rapamycin and INK128). Further, mTORi were found to enhance the selective killing of HIV-1-infected myeloid and T-cell reservoirs at the exclusion of uninfected cells, potentially via inhibition of viral transcription/translation and induction of autophagy. Collectively, the proposed regimen using cART, IR, and mTORi presents a novel approach allowing for the targeting of viral reservoirs, prevention of immune hyper-activation, and selectively killing latently infected HIV-1 cells.

Anti-HIV Activity of Standard Combined Antiretroviral Therapy in Primary Cells Is Intensified by CCR5-Targeting Drugs.

The efficacy of combined antiretroviral therapy (cART) against HIV-1 is evidenced by reduction of plasma viremia, disease progression, viral transmission, and mortality. However, major challenges still remain in HIV-1 management, especially the emergence of resistant strains and the persistence of viral reservoirs, apparent after cART treatment interruption. Efforts are ongoing to explore the most effective means to intensify cART and successfully control residual viral replication. We anticipate that the reduction by cART of HIV-1 reservoirs could be further enhanced by combining cART with entry inhibitors and drugs that silence CCR5 expression. CCR5-targeting drugs are attractive option because of their low side effects when combined with other antiretroviral drugs. The concept that their inclusion would be effective has been supported by the reduction in two long terminal repeat unintegrated circular DNA, a marker for new infections, when CCR5-targeting drugs are added to standard antiretroviral treatment. This study is, in part, an extension of our previous study demonstrating greater preservation of human CD4+ T-cells and CD4+/CD8+ cell ratios in HIV-infected CD34+ NSG mice when CCR5-targeting drugs were included with standard cART. In this study, we treated HIV-1-infected cell cultures with cART or cART plus CCR5-targeting drugs (maraviroc and rapamycin). We found that treatment intensification with CCR5-targeting drugs led to a significant reduction of HIV-1 replication in peripheral blood ononuclear cells (PBMCs), as judged by measured viral DNA copies and p24 levels. Our data provide proof of principle for the benefit of adding CCR5-targeting drugs to traditional, standard cART to further lower viremia and subsequently reduce viral reservoirs in clinical settings, while potentially lowering side effects by reducing cART concentrations.

Use of Humanized Mouse Models for Studying HIV-1 Infection, Pathogenesis and Persistence.

Despite decades of intensive basic and clinical research efforts, there is still no successful vaccine candidate against human immunodeficiency virus (HIV-1). Standard combined antiretroviral therapy (cART) has been successfully developed and has given remarkable results suppressing HIV-1 infection and transmission. However, cART cannot fully clear the virus from the infected patients. A cure for HIV-1 is highly desirable to stop both the spread of the virus in humans and disease progression in HIV-1 patients. A safe and effective cure strategy for HIV-1 infection will require appropriate animal models that properly mimic HIV-1 infection and advance HIV-1 cure research. Animal models have been a crucial tool in the drug discovery process for investigation of HIV-1 disease mainly in preclinical evaluations of antiretroviral drugs and vaccines. An ideal animal model should recapitulate the main aspects of human-specific HIV-1 infection and pathogenesis with their associated immune responses, while permitting invasive antiretroviral studies. The best humanized mouse models would allow a thorough evaluation of antiretroviral strategies that are aimed towards reducing the establishment and size of the HIV-1 reservoirs. In this review, we evaluate multiple humanized mouse models while presenting their strengths and limitations for HIV-1 research. These humanized mouse models have been tailored in recent decades and heavily employed to address specific quintessential and remaining questions of HIV-1 persistence, pathogenesis and ultimately, eradication.

Novel Chronic Mouse Model of Cerebral Cavernous Malformations.

Background and Purpose- Cerebral cavernous malformations (CCMs) are vascular malformations of the brain that lead to cerebral hemorrhages. A pharmacological treatment is needed especially for patients with nonoperable deep-seated lesions. We and others obtained CCM mouse models that were useful for mechanistic studies and rapid trials testing the preventive effects of candidate drugs. The shortened lifespan of acute mouse models hampered evaluation of compounds that would not only prevent lesion appearance but also cure preexisting lesions. Indirubin-3'-monoxime previously demonstrated its efficacy to reverse the cardiac phenotype of ccm2m201 zebrafish mutants and to prevent lesion development in an acute CCM2 mouse model. In the present article, we developed and characterized a novel chronic CCM2 mouse model and evaluated the curative therapeutic effect of indirubin-3'-monoxime after CCM lesion development. Methods- The chronic mouse model was obtained by a postnatal induction of brain-endothelial-cell-specific ablation of the Ccm2 gene using the inducible Slco1c1-CreERT2 mouse line. Results- We obtained a fully penetrant novel CCM chronic mouse model without any obvious off-target phenotypes and compatible with long-term survival. By 3 months of age, CCM lesions ranging in size from small isolated lesions to multiple caverns developed throughout the brain. Lesion burden was quantified in animals from 1 week to 5 months of age. Clear signs of intracerebral hemorrhages were noticed in brain-endothelial-cell-specific ablation of the Ccm2 gene. In contrast with its preventive effect in the acute CCM2 mouse model, a 20 mg/kg indirubin-3'-monoxime treatment for 3 weeks in 3-month old animals neither had any beneficial effect on the lesion burden nor alleviated cerebral hemorrhages. Conclusions- The brain-endothelial-cell-specific ablation of the Ccm2 gene chronic model is a strongly improved disease model for the CCM community whose challenge today is to decipher which candidate drugs might have a curative effect on patients' preexisting lesions. Visual Overview- An online visual overview is available for this article.

Chronic, Acute, and Reactivated HIV Infection in Humanized Immunodeficient Mouse Models.

Humanized NOD/SCID/IL-2 receptor γ-chainnull mice recapitulate some features of human immunity, which can be exploited in basic and pre-clinical research on infectious diseases. Described here are three models of humanized immunodeficient mice for studying the dynamics of HIV infection. The first is based on the intrahepatic injection of CD34+ hematopoietic stem cells in newborn mice, which allows for the reconstitution of several blood and lymphoid tissue-confined cells, followed by infection with a reference HIV strain. This model allows monitoring for up to 36 weeks post-infection and is hence called the chronic model. The second and third models are referred to as the acute and reactivation models, in which peripheral blood mononuclear cells are intraperitoneally injected in adult mice. In the acute model, cells from a healthy donor are engrafted through the intraperitoneal route, followed by infection with a reference HIV strain. Finally, in the reactivation model, cells from an HIV-infected donor under antiretroviral therapy are engrafted via the intraperitoneal route. In this case, a drug-free environment in the mouse allows for virus reactivation and an increase in viral load. The protocols provided here describe the conventional experimental approach for humanized, immunodeficient mouse models of HIV infection.

Glycan-dependent HIV-specific neutralizing antibodies bind to cells of uninfected individuals.

A number of highly potent and broadly neutralizing antibodies (bNAbs) against the human immunodeficiency virus (HIV) have recently been shown to prevent transmission of the virus, suppress viral replication, and delay plasma viral rebound following discontinuation of antiretroviral therapy in animal models and infected humans. However, the degree and extent to which such bNAbs interact with primary lymphocytes have not been fully delineated. Here, we show that certain glycan-dependent bNAbs, such as PGT121 and PGT151, bind to B, activated T, and natural killer (NK) cells of HIV-infected and -uninfected individuals. Binding of these bNAbs, particularly PGT121 and PGT151, to activated CD4+ and CD8+ T cells was mediated by complex-type glycans and was abrogated by enzymatic inhibition of N-linked glycosylation. In addition, a short-term incubation of PGT151 and primary NK cells led to degranulation and cellular death. Our data suggest that the propensity of certain bNAbs to bind uninfected/bystander cells has the potential for unexpected outcomes in passive-transfer studies and underscore the importance of antibody screening against primary lymphocytes.

Suppression of Active HIV-1 Infection in CD34+ Hematopoietic Humanized NSG Mice by a Combination of Combined Antiretroviral Therapy and CCR5 Targeting Drugs.

Significant progress has been made in the diagnostics and treatment of AIDS since the discovery of the human immunodeficiency virus type 1 (HIV-1) in 1983. The remarkable effectiveness of combined antiretroviral therapy (cART) is evidenced by mortality reduction, control of peripheral blood viral load, and in a nearly normal quality of HIV patients' lives. Remaining obstacles in treatment and cure are drug toxicities and side effects, viral resistance, persistence of HIV-1 reservoirs on termination of cART treatment, the cost of lifelong antiretroviral therapy, and the stigma associated with taking antiretroviral drugs. As determined by plasma viral RNA and peripheral blood mononuclear cells (PBMC) proviral DNA, we show improved suppression of productive HIV infection in human CD34+ hematopoietic stem cell-engrafted NOD (nonobese diabetic)-SCID (severe combined immunodeficiency)-il2rg-/- (NSG) mice by combined treatment with cART and CCR5 targeting drugs, compared with cART alone, as well as an increased preservation of human CD4+ T cells (defined as CD45+ CD3+ CD4+ cells) and CD4+/CD8+ cell ratios in infected mice. The data also suggest a possible reduction in viral reservoirs. Our data confirm that this animal model is suitable for detection of productive HIV infection, replication, and establishment of viral reservoirs. The data also provide proof of principle for the utility of combining CCR5 targeting drugs, maraviroc and rapamycin, with traditional cART to improve control of viremia and reduce viral reservoirs. This study thus serves as a model for future HIV-1 studies that could lead to the clinical development of new generations of antiretroviral drugs.

Role of the inflammasomes in HIV-associated neuroinflammation and neurocognitive disorders.

HIV associated neurocognitive disorders (HAND) is a unique form of neurological impairment that stems from HIV. This disease and its characteristics can be accredited to incorporation of DNA and mRNA of HIV-1 into the CNS. A proper understanding of the intricacies of HAND and the underlying mechanisms associated with corresponding immune reactions are vital for the potential development of a reliable treatment for HAND. A common phenomenon observed in CNS cells, specifically microglia, that are infected with HAND is inflammation, which is a consequence of the activation of innate immune response due to a variety of stimuli, in this case, being the HIV infection. The CNS based inflammation is mediated by the production of cytokines, chemokines, reactive oxygen species, and secondary messengers, which occurs at CNS glia, endothelial cells and peripherally derived immune cells. Inflammasomes play a significant role with regard to neuroinflammation due to their ability to dictate the activation of various inflammatory responses. Certain stimuli can result in the activation of caspase-1; hence, leading to the processing of interleukin-1ß and interleukin-18 pro-inflammatory cytokines. The processed IL-1ß and IL-18 activate signaling pathways that begin the process of neuroinflammation. Due to the fact that the NLRP3 inflammasome is the most abundant in the CNS, it is the most extensively investigated inflammasome with regard to the nervous system. Due to the importance of neuroinflammation in the evolution of HAND and proliferation of neuroinflammation due to HAND, it can be concluded that there exists a relationship between HAND and inflammasomes. The aim of our review is to consolidate current knowledge of important mechanisms in HAND, specifically related to its relationship with neuroinflammation and inflammasomes to shed light on a possible improved treatment for HAND.