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.

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.

Contribution of the Microbiota to Intestinal Homeostasis and its Role in the Pathogenesis of HIV-1 Infection

During HIV infection, massive destruction of CD4+ T cells ensues, preferentially depleting the Th17 subset at the gut-associated lymphoid tissue (GALT), leading to a loss of mucosal integrity and an increase in cell permeability. This process favors microbial translocation between the intestinal lumen and the circulatory system, contributing to persistent immune activation and chronic inflammation characteristic of HIV infection. Thus, the gut microbiota plays an integral role in maintaining the structure and function of the mucosal barrier, a critical factor for immune homeostasis. However, in the context of HIV infection, changes in the gut microbiota have been reported and have been linked to disease progression. Here, we review evidence for the role of the gut microbiota in intestinal homeostasis, its contribution to HIV pathogenesis, as well as its use in the development of therapeutic strategies.

What Aging with HIV Means in the Year 2019

In Greek mythology, Tithonus was granted eternal life but not eternal youth. As time passes he withers, slowly losing his health and all that he knew, lamenting a cruel immortality.¹.

Understanding the Intersection of Young Age, Mucosal Injury, and HIV Susceptibility

Adolescent boys and girls are disproportionately affected in the current HIV epidemic. Numerous sociobehavioral studies have addressed the indirect drivers surrounding this vulnerability-for example, socioeconomic, geographical locale, and all forms of violence. However, the direct factors that may influence infection, such as the anatomical and physiological maturation of the anogenital tracts of adolescents or the trauma and wound-healing processes of injured mucosal tissue, are understudied and represent a gap within the HIV prevention field. This article reviews the epidemiology of HIV infection and violence in adolescents and the available basic science knowledge attending this research area. More importantly, this review highlights the most critical gaps that need to be addressed to design preventive interventions that are safe and effective for this population, which is key to ending the HIV pandemic.

Refining Current Scientific Priorities and Identifying New Scientific Gaps in HIV-Related Heart, Lung, Blood, and Sleep Research

The National Heart, Lung, and Blood Institute (NHLBI) AIDS Program's goal is to provide direction and support for research and training programs in areas of HIV-related heart, lung, blood, and sleep (HLBS) diseases. To better define NHLBI current HIV-related scientific priorities and with the goal of identifying new scientific priorities and gaps in HIV-related HLBS research, a wide group of investigators gathered for a scientific NHLBI HIV Working Group on December 14-15, 2015, in Bethesda, MD. The core objectives of the Working Group included discussions on: (1) HIV-related HLBS comorbidities in the antiretroviral era; (2) HIV cure; (3) HIV prevention; and (4) mechanisms to implement new scientific discoveries in an efficient and timely manner so as to have the most impact on people living with HIV. The 2015 Working Group represented an opportunity for the NHLBI to obtain expert advice on HIV/AIDS scientific priorities and approaches over the next decade.

Regulatory T Cell Effect on CD8+ T Cell Responses to Human Herpesvirus 8 Infection and Development of Kaposi's Sarcoma

We assessed CD8⁺ T cell reactivity to human herpesvirus 8 (HHV-8; Kaposi's sarcoma [KS]-associated herpesvirus) and the role of CD4⁺CD25^hiFoxP3⁺ regulatory T cells (Treg) in HHV-8- and HIV-coinfected participants of the Multicenter AIDS Cohort Study who did or did not develop KS. There were similarly low CD8⁺ T cell interferon-γ responses to MHC class I-restricted epitopes of HHV-8 lytic and latent proteins over 5.7 years before KS in participants who developed KS compared to those who did not. T cell reactivity to HHV-8 antigens was low relative to responses to a combination of cytomegalovirus, Epstein-Barr virus and influenza A virus (CEF) peptide epitopes, and dominant HIV peptide epitopes. There was no change in %Treg in the HHV-8- and HIV-coinfected participants who did not develop KS, whereas there was a significant increase in %Treg in HHV-8- and HIV-coinfected participants who developed KS beginning 1.8 years before development of KS. Removal of Treg enhanced HHV-8-specific T cell responses in HHV-8- and HIV-coinfected participants who did or did not develop KS, with a similar pattern observed in response to CEF and HIV peptides. Thus, long-term, low levels of anti-HHV-8 CD8⁺ T cell reactivity were present in both HHV-8- and HIV-coinfected men who did and did not develop KS. This was related to moderately enhanced Treg function.

Genome-Wide Analyses Reveal Gene Influence on HIV Disease Progression and HIV-1C Acquisition in Southern Africa

Sub-Saharan Africans infected with HIV-1C make up the largest AIDS patient population in the world and exhibit large heterogeneity in disease progression before initiating antiretroviral therapy. To identify host variants associated with HIV disease progression, we performed genome-wide association studies on a total of 556 treatment-naive HIV-infected individuals in Botswana. We characterized the pattern of HIV disease progression using a novel functional principal component analysis, which can better capture longitudinal CD4 and viral load (VL) trajectories. Two single-nucleotide polymorphisms (SNPs) near HCG22 (chr6, peak variant rs2535307, combined p = 3.72 × 10^-7, minor allele as risky allele) and CCNG1 (chr5, peak variant kgp22385164, combined p = 1.88 × 10^-6, minor allele as risky allele) were significantly associated with CD4 and VL dynamics. Inspection of SNPs in these gene regions in a third Botswana cohort (using GWATCH) also revealed a strong association of HCG22 with HIV-1C acquisition, suggesting that this region is associated with infection as well as disease progression. Our study uncovered two genetic regions that are significant and have specific effects on HIV-1C acquisition or progression in sub-Saharan Africans, and the result suggested new potential targets for AIDS prevention and treatment. In addition, our results also indicate the possibility of using genetic markers as HIV disease progression indicators in sub-Saharan Africans to prioritize fast progressors for antiretroviral treatment.

Biased Nucleotide Composition and Differential Codon Usage Pattern in HIV-1 and HIV-2

HIV-1 and HIV-2 are closely related retroviruses with differences in pathogenicity and geographic distribution. HIV-2 infection is associated with slower disease progression and transmission, longer latency period, low or undetectable plasmatic viral loads, and reduced likelihood of progression to AIDS, compared to HIV-1. In this investigation, we analyzed HIV-2 genes and genomes and compared them with that of HIV-1 belonging to various subtypes. Comparative analysis of the effective number of codons (ENC) for each of the nine genes of the two viruses revealed that the tat gene of HIV-2 had a higher ENC value compared to HIV-1 tat, reflecting lower levels of expression of HIV-2 tat. Lower levels of tat protein particularly during the early stages of infection could result in a lower viral load, lower viral set point, and delayed progression of disease in HIV-2-infected individuals compared to HIV-1-infected subjects. Furthermore, the GC3 composition of the regulatory genes of HIV-2 was ≥50%, suggesting a firm effort by these viruses to adapt themselves to evolutionary survival. We hypothesize that differential codon usage could be one of the possible factors that could contribute to the diminished pathogenicity of HIV-2 in the host as compared to HIV-1.

Soluble Factors Secreted by Endothelial Cells Allow for Productive and Latent HIV-1 Infection in Resting CD4+ T Cells

In vitro, it is difficult to infect resting CD4⁺ T cells with human immunodeficiency virus type 1 (HIV), but infections readily occur in vivo. Endothelial cells (ECs) interact with resting CD4⁺ T cells in vivo, and we found previously that EC stimulation leads to productive and latent HIV infection of resting CD4⁺ T cells. In this study, we further characterize the interactions between EC and resting T cells. We found that resting CD4⁺ T cells did not require direct contact with EC for productive and/or latent infection to occur, indicating the involvement of soluble factors. Among 30 cytokines tested in a multiplex enzyme-linked immunosorbent assay (ELISA), we found that expressions for IL-6, IL-8, and CCL2 were much higher in EC-stimulated resting T cells than resting T cells cultured alone. IL-6 was found to be the soluble factor responsible for inducing productive infection of resting T cells, although direct contact with EC had an added effect. However, none of the cytokines tested, IL-6, IL-8, or CCL2, induced additional latent infection in resting T cells, suggesting that unidentified cytokines were involved. Intracellular molecules MURR1, c-Jun N-terminal kinase (JNK), and glucose transporter-1 (GLUT1) were previously shown in blocking HIV infection of resting CD4⁺ T cells. We found that the concentrations of these proteins were not significantly different in resting T cells before and after stimulation by EC; therefore, they are not likely involved in EC stimulation of resting CD4⁺ T cells, and a new mechanism is yet to be identified.