HIV Controllers Have Low Inflammation Associated with a Strong HIV-Specific Immune Response in Blood

HTLV-2 Enhances CD8+ T Cell-Mediated HIV-1 Inhibition and Reduces HIV-1 Integrated Proviral Load in People Living with HIV-1

People living with HIV-1 and HTLV-2 concomitantly show slower CD4⁺ T cell depletion and AIDS progression, more frequency of the natural control of HIV-1, and lower mortality rates. A similar beneficial effect of this infection has been reported on HCV coinfection reducing transaminases, increasing the spontaneous clearance of HCV infection and delaying the development of hepatic fibrosis. Given the critical role of CD8⁺ T cells in controlling HIV-1 infection, we analysed the role of CD8⁺ T cell-mediated cytotoxic activity in coinfected individuals living with HIV-1. One hundred and twenty-eight individuals living with HIV-1 in four groups were studied: two groups with HTLV-2 infection, including individuals with HCV infection (N = 41) and with a sustained virological response (SVR) after HCV treatment (N = 25); and two groups without HTLV-2 infection, including individuals with HCV infection (N = 25) and with a sustained virological response after treatment (N = 37). We found that CD8⁺ T cell-mediated HIV-1 inhibition in vitro was higher in individuals with HTLV-2. This inhibition activity was associated with a higher frequency of effector memory CD8⁺ T cells, higher levels of granzyme A and granzyme B cytolytic enzymes, and perforin. Hence, cellular and soluble cytolytic factors may contribute to the lower HIV-1 pre-ART viral load and the HIV-1 proviral load during ART therapy associated with HTLV-2 infection. Herein, we confirmed and expanded previous findings on the role of HTLV-2 in the beneficial effect on the pathogenesis of HIV-1 in coinfected individuals.

Toll-like Receptor 2 Is Associated with the Immune Response, Apoptosis, and Angiogenesis in the Mammary Glands of Dairy Cows with Clinical Mastitis

Toll-like receptor 2 (TLR2) plays a crucial role in bacterial recognition and the host immune response during infection. However, its function and downstream biological processes (BPs) in the mammary glands (MGs) of Holstein cows with clinical mastitis (CM) are not fully understood. This study aimed to comprehensively identify the BPs and differentially expressed proteins (DEPs) associated with the bacterial response and TLR2 using data-independent acquisition (DIA) proteomic data. A possible mechanism for the action of TLR2 was proposed, and the results suggested that the expression levels of TLR2 and caspase 8 (CASP8) were positively correlated with the apoptosis of MGs. The expression patterns of TLR2 and TEK receptor tyrosine kinase 2 (Tie2) were negatively correlated with angiogenesis. These results indicated that TLR2 might promote apoptosis in mammary epithelial cells (MECs) and vascular endothelial cells (VECs) via upregulation of CASP8 expression, and inhibition of angiogenesis in VECs via downregulation of Tie2 expression in dairy cows with CM. In conclusion, TLR2 is associated with inflammation, apoptosis, and angiogenesis in the MGs of dairy cows with bacteria-induced mastitis. These results contribute to a deeper understanding of the pathogenic mechanisms and provide the knowledge needed for developing the prevention and treatment of dairy mastitis.

Omic Technologies in HIV: Searching Transcriptional Signatures Involved in Long-Term Non-Progressor and HIV Controller Phenotypes

This article reviews the main discoveries achieved by transcriptomic approaches on HIV controller (HIC) and long-term non-progressor (LTNP) individuals, who are able to suppress HIV replication and maintain high CD4+ T cell levels, respectively, in the absence of antiretroviral therapy. Different studies using high throughput techniques have elucidated multifactorial causes implied in natural control of HIV infection. Genes related to IFN response, calcium metabolism, ribosome biogenesis, among others, are commonly differentially expressed in LTNP/HIC individuals. Additionally, pathways related with activation, survival, proliferation, apoptosis and inflammation, can be deregulated in these individuals. Likewise, recent transcriptomic studies include high-throughput sequencing in specific immune cell subpopulations, finding additional gene expression patterns associated to viral control and/or non-progression in immune cell subsets. Herein, we provide an overview of the main differentially expressed genes and biological routes commonly observed on immune cells involved in HIV infection from HIC and LTNP individuals, analyzing also different technical aspects that could affect the data analysis and the future perspectives and gaps to be addressed in this field.

Expresión de los componentes del inflamasoma y su relación con los marcadores de riesgo cardiovascular en personas con infección por HIV-1

Introducción. La infección por el HIV-1 induce un estado de inflamación crónico en el que participan los inflamasomas. El incremento de los parámetros inflamatorios es mayor en individuos con replicación viral activa que en aquellos con control de la replicación viral. Este proceso desencadena alteraciones metabólicas relacionadas con cambios en el perfil lipídico, lo cual podría incrementar el riesgo de eventos cardiovasculares, incluso en pacientes con terapia antirretroviral.Objetivo. Establecer si existe correlación entre la expresión de los componentes de los inflamasomas y los marcadores de riesgo cardiovascular en individuos con control de la replicación viral y en aquellos con replicación viral activa con terapia antirretroviral o sin ella. Materiales y métodos. Se estudiaron 13 individuos con control de la replicación viral y 40 con replicación viral activa (19 sin terapia antirretroviral y 31 con terapia). Se evaluaron los marcadores clásicos de riesgo cardiovascular y se cuantificó mediante RT-PCR la expresión de los componentes de los inflamasomas (NLRP1, NLRP3, NLRC4, AIM2, ASC, IL-1β, IL-18 y caspasa-1), TLR2, TLR4, TGF-β e IL-10.Resultados. Se observó que los pacientes con replicación viral activa y con terapia antirretroviral presentaron un incremento en la expresión de TLR2, TLR4 e IL-18, comparados con los controladores del HIV-1. Además, mostraron grandes valores de triglicéridos y lipoproteína de muy baja densidad (Very Low Density Lipopretein, VLDL), lo que se correlaciona positivamente con la expresión de los componentes de los inflamasomas NLRP1, NLRP3, NLRC4, AIM2, ASC y caspasa-1.Conclusión. El aumento en la expresión de los componentes de los inflamasomas en los individuos con replicación viral activa y con terapia antirretroviral se correlacionó con las concentraciones de triglicéridos y VLDL, lo que sugiere el papel de la activación inmunitaria y la terapia antirretroviral en el riesgo cardiovascular.

Peripheral blood CD4+CCR6+ compartment differentiates HIV-1 infected or seropositive elite controllers from long-term successfully treated individuals

HIV-1 infection induces a chronic inflammatory environment not restored by suppressive antiretroviral therapy (ART). As of today, the effect of viral suppression and immune reconstitution in people living with HIV-1 (PLWH) has been well described but not completely understood. Herein, we show how PLWH who naturally control the virus (PLWH_EC) have a reduced proportion of CD4⁺CCR6⁺ and CD8⁺CCR6⁺ cells compared to PLWH on suppressive ART (PLWH_ART) and HIV-1 negative controls (HC). Expression of CCR2 was reduced on both CD4⁺, CD8⁺ and classical monocytes in PLWH_EC compared to PLWH_ART and HC. Longer suppressive therapy, measured in the same patients, decreased number of cells expressing CCR2 on all monocytic cell populations while expression on CD8⁺ T cells increased. Furthermore, the CD4⁺CCR6⁺/CCR6^- cells exhibited a unique proteomic profile with a modulated energy metabolism in PLWH_EC compared to PLWH_ART independent of CCR6 status. The CD4⁺CCR6⁺ cells also showed an enrichment in proteins involved in apoptosis and p53 signalling in PLWH_EC compared to PLWH_ART, indicative of increased sensitivity towards cell death mechanisms. Collectively, this data shows how PLWH_EC have a unique chemokine receptor profile that may aid in facilitating natural control of HIV-1 infection.

Senotherapeutics in Cancer and HIV

Cellular senescence is a stress-response mechanism that contributes to homeostasis maintenance, playing a beneficial role during embryogenesis and in normal adult organisms. In contrast, chronic senescence activation may be responsible for other events such as age-related disorders, HIV and cancer development. Cellular senescence activation can be triggered by different insults. Regardless of the inducer, there are several phenotypes generally shared among senescent cells: cell division arrest, an aberrant shape, increased size, high granularity because of increased numbers of lysosomes and vacuoles, apoptosis resistance, defective metabolism and some chromatin alterations. Senescent cells constitute an important area for research due to their contributions to the pathogenesis of different diseases such as frailty, sarcopenia and aging-related diseases, including cancer and HIV infection, which show an accelerated aging. Hence, a new pharmacological category of treatments called senotherapeutics is under development. This group includes senolytic drugs that selectively attack senescent cells and senostatic drugs that suppress SASP factor delivery, inhibiting senescent cell development. These new drugs can have positive therapeutic effects on aging-related disorders and act in cancer as antitumor drugs, avoiding the undesired effects of senescent cells such as those from SASP. Here, we review senotherapeutics and how they might affect cancer and HIV disease, two very different aging-related diseases, and review some compounds acting as senolytics in clinical trials.

Integrative proteo-transcriptomic and immunophenotyping signatures of HIV-1 elite control phenotype: A cross-talk between glycolysis and HIF signaling

Natural control of HIV-1 is a characteristic of <1% of HIV-1-infected individuals, so called elite controllers (EC). In this study, we sought to identify signaling pathways associated with the EC phenotype using integrative proteo-transcriptomic analysis and immunophenotyping. We found HIF signaling and glycolysis as specific traits of the EC phenotype together with dysregulation of HIF target gene transcription. A higher proportion of HIF-1α and HIF-1β in the nuclei of CD4⁺ and CD8⁺ T cells in the male EC were observed, indicating a potential increased activation of the HIF signaling pathway. Furthermore, intracellular glucose levels were elevated in EC even as the surface expression of the metabolite transporters Glut1 and MCT-1 were decreased on lymphocytes indicative of unique metabolic uptake and flux profile. Combined, our data show that glycolytic modulation and altered HIF signaling is a unique feature of the male EC phenotype that may contribute to natural control of HIV-1.

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Proteo-transcriptomic integration identifying features of EC phenotype

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Sex-specific differences in EC phenotypes

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Enrichment of glycolysis and HIF signaling, a unique feature in the male EC

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Enrichment of HIF signaling independent on HIF-1α protein levels in EC

Apathy is not associated with a panel of biomarkers in older adults with HIV disease

OBJECTIVE

Apathy is prevalent in HIV disease and can significantly impact personal well-being; however, little is known about its neurobiological substrates in persons with HIV (PWH) disease.

METHODS

This cross-sectional, correlational study examined the association between apathy and several plasma biomarkers (tumor necrosis factor alpha, kynurenine, tryptophan, quinolinic acid, brain-derived neurotrophic factor, glial fibrillary acidic protein, neurofilament light chain, and phosphorylated tau at position threonine 181) in 109 PWH and 30 seronegative participants ages 50 and older. Apathy was measured with a composite score derived from subscales of the Frontal Systems Behavior Scale and the Profile of Mood States.

RESULTS

Multiple regressions showed that PWH had significantly greater severity of apathy symptoms, independent of both data-driven and conceptually-based covariates. Pairwise correlations in the PWH sample indicated that apathy was not significantly associated with any of the measured biomarkers and all of the effect sizes were small.

CONCLUSION

Findings suggest that apathy is not strongly associated with peripheral biomarkers of inflammation, neurotrophic support, or neurodegeneration in older PWH. Limitations of this study include the cross-sectional design, the use of self-report measures of apathy, and low rates of viremia. Longitudinal studies in more representative samples of PWH that include a more comprehensive panel of fluid biomarkers, informant and behavioral indicators of apathy, and relevant psychosocial factors might help to further clarify the neurobiological substrates of this complex neuropsychiatric phenomenon.

Distinct transcriptomic profiles of naïve CD4+ T cells distinguish HIV-1 infected patients initiating antiretroviral therapy at acute or chronic phase of infection

We analyzed the whole transcriptome characteristics of blood CD4+ T naïve (T_N) cells isolated from HIV-1 infected patients starting ART at acute (early ART = EA; n = 13) or chronic (late ART = LA; n = 11) phase of infection and controls (C; n = 15). RNA sequencing revealed 389 differentially expressed genes (DEGs) in EA and 810 in LA group in relation to controls. Comparison of the two groups of patients showed 183 DEGs. We focused on DEGs involved in apoptosis, inflammation and immune response. Clustering showed a poor separation of EA from C suggesting that these two groups present a similar transcriptomic profile of CD4+ T_N cells. The comparison of EA and LA patients resulted in a high cluster purity revealing that different biological dysfunctions characterize EA and LA patients. The upregulated expression of several inflammatory chemokine genes distinguished the patient groups from C; CCL2 and CCL7, however, were downregulated in EA compared to LA patients. BCL2, an anti-apoptotic factor pivotal for naïve T cell homeostasis, distinguished both EA and LA from C. The expression of several DEGs involved in different inflammatory processes (TLR4, PTGS2, RAG1, IFNA16) was lower in EA compared LA. We conclude that although the transcriptome of CD4+ T_N cells isolated from patients initiating ART at acute infection reveals a more quiescent phenotype, the survival profile of these cells still appears to be affected. Our results show that the detrimental process of inflammation is under more efficient control in EA patients.

Evolution toward beta common chain receptor usage links the matrix proteins of HIV-1 and its ancestors to human erythropoietin

The HIV-1 matrix protein p17 (p17) is a pleiotropic molecule impacting on different cell types. Its interaction with many cellular proteins underlines the importance of the viral protein as a major determinant of human specific adaptation. We previously showed the proangiogenic capability of p17. Here, by integrating functional analysis and receptor binding, we identify a functional epitope that displays molecular mimicry with human erythropoietin (EPO) and promotes angiogenesis through common beta chain receptor (βCR) activation. The functional EPO-like epitope was found to be present in the matrix protein of HIV-1 ancestors SIV originated in chimpanzees (SIVcpz) and gorillas (SIVgor) but not in that of HIV-2 and its ancestor SIVsmm from sooty mangabeys. According to biological data, evolution of the EPO-like epitope showed a clear differentiation between HIV-1/SIVcpz-gor and HIV-2/SIVsmm branches, thus highlighting this epitope on p17 as a divergent signature discriminating HIV-1 and HIV-2 ancestors. P17 is known to enhance HIV-1 replication. Similarly to other βCR ligands, p17 is capable of attracting and activating HIV-1 target cells and promoting a proinflammatory microenvironment. Thus, it is tempting to speculate that acquisition of an epitope on the matrix proteins of HIV-1 ancestors capable of triggering βCR may have represented a critical step to enhance viral aggressiveness and early human-to-human SIVcpz/gor dissemination. The hypothesis that the p17/βCR interaction and βCR abnormal stimulation may also play a role in sustaining chronic activation and inflammation, thus marking the difference between HIV-1 and HIV-2 in term of pathogenicity, needs further investigation.

Pidotimod and Immunological Activation in Individuals Infected with HIV

BACKGROUND

The improvements in HIV infection therapy and the large availability of antiretroviral drugs have led to an increased survival among HIV infected people, and simultaneously to a raised morbidity and mortality due to not-AIDS-related events in this group compared to the general population. An increased systemic inflammation and a persistent immune activation play a pivotal role in determining high rates of non-AIDS comorbidities. In the last years, many natural or synthetic immunomodulatory molecules acting by different mechanisms have been conceived. Pidotimod is a synthetic dipeptide molecule showing immunomodulatory properties. The aim of this pilot study was to evaluate the effects of Pidotimod supplementation on residual inflammation in HIV infected population.

METHODS

Forty HIV positive individuals under cART were enrolled: 30 were treated with Pidotimod supplementation (study group) and 10 served as control group (without Pidotimod supplementation). For all participants, Cystatin C, PCR, ESR, microalbuminuria, TNF-α, INF-γ, IL-4, IL-10, IL1β, IL-18 and IL-2 were measured at enrolment (T0), 4 weeks after of Pidotimod supplementation (T1), and 4 weeks after completing supplementation (T2).

RESULTS

In HIV positive participants treated with Pidotimod, the evaluation of cytokine levels showed that IL-10, IFN gamma, and IL-4 were significantly higher at enrolment compared to the control group. The increase under Pidotimod treatment persisted after supplementation suspension, while the pro-inflammatory cytokines levels were reduced. Salivary IgA also increased during 4 weeks of supplementation and persisted at 4 weeks after completing supplementation. On the other hand, the Cystatin C and microalbuminuria levels decreased over time, at a greater extent the Cystatin C serum levels.

CONCLUSION

The study findings showed that the HIV population receiving Pidotimod achieved a rebalancing of pro-inflammatory and anti-inflammatory cytokines as well as a significant reduction in cystatin C levels. The treatment further allowed for an increase in salivary IgA levels at all the analyzed times, as a secondary event to a remodulation of the immunological status obtained with pidotimod. This approach could represent a new way to design new intervention strategies aimed at improving the persistent immune activation status in the virologically suppressed HIV population.

Elevated Numbers of HIV-Specific Poly-Functional CD8+ T Cells With Stem Cell-Like and Follicular Homing Phenotypes in HIV-Exposed Seronegative Individuals

HIV-specific CD8⁺ T cells are known to play a key role in viral control during acute and chronic HIV infection. Although many studies have demonstrated the importance of HIV-specific CD8⁺ T cells in viral control, its correlation with protection against HIV infection remains incompletely understood. To better understand the nature of the immune response that contributes to the early control of HIV infection, we analyzed the phenotype, distribution and function of anti-viral CD8⁺ T cells in a cohort of HIV-exposed seronegative (HESN) women, and compared them with healthy controls and HIV-infected individuals. Further, we evaluated the in vitro viral inhibition activity of CD8⁺ T cells against diverse HIV-1 strains. We found that the HESN group had significantly higher levels of CD8⁺ T cells that express T-stem cell-like (TSCM) and follicular homing (CXCR5⁺) phenotype with more effector like characteristics as compared to healthy controls. Further, we observed that the HESN population had a higher frequency of HIV-specific poly-functional CD8⁺ T cells with robust in vitro virus inhibiting capacity against different clades of HIV. Overall, our results demonstrate that the HESN population has elevated levels of HIV-specific poly-functional CD8⁺ T cells with robust virus inhibiting ability and express elevated levels of markers pertaining to TSCM and follicular homing phenotype. These results demonstrate that future vaccine and therapeutic strategies should focus on eliciting these critical CD8⁺ T cell subsets.

Dangerous liaisons? The role of inflammation and comorbidities in HIV and SARS-CoV-2 infection

INTRODUCTION

In people living with HIV (PLWH), immune activation and inflammation levels are high even when viral suppression is maintained, potentially contributing to several comorbidities, and hampering the immune response to infections such as the recent SARS-CoV-2 disease 2019 (COVID-19).

AREAS COVERED

Immune activation and inflammation play a role in SARS-CoV-2 infection. Severe COVID-19 patients may experience cytokine release syndrome (CRS), leading to alveolar damage, pulmonary fibrinolysis, dysregulated coagulation, and pulmonary injury. Into the systemic circulation, cytokines in excess might leak out of pulmonary circulation, causing systemic symptoms and possibly a multiple-organ dysfunction syndrome. Preexisting comorbidities are also linked to worse COVID-19 outcome: studies suggest that diabetes and hypertension are linked to higher mortality rates. Such comorbidities are more frequent in PLWH, but it is unclear if they have worse outcomes in the case of COVID-19. The literature was searched in PubMed/MEDLINE and EMBASE, and manually in COVID-19 resources.

EXPERT OPINION

A body of evidence shows that HIV and SARS-CoV-2 are able to activate inflammatory pathways, acute in the case of SARS-CoV-2, chronic in the case of HIV, while the comorbidities seem to represent, in the first case, a contributory cause, in the second an effect of the virus-induced damage.

PLA2G1B is involved in CD4 anergy and CD4 lymphopenia in HIV-infected patients

The precise mechanism leading to profound immunodeficiency of HIV-infected patients is still only partially understood. Here, we show that more than 80% of CD4+ T cells from HIV-infected patients have morphological abnormalities. Their membranes exhibited numerous large abnormal membrane microdomains (aMMDs), which trap and inactivate physiological receptors, such as that for IL-7. In patient plasma, we identified phospholipase A2 group IB (PLA2G1B) as the key molecule responsible for the formation of aMMDs. At physiological concentrations, PLA2G1B synergized with the HIV gp41 envelope protein, which appears to be a driver that targets PLA2G1B to the CD4+ T cell surface. The PLA2G1B/gp41 pair induced CD4+ T cell unresponsiveness (anergy). At high concentrations in vitro, PLA2G1B acted alone, independently of gp41, and inhibited the IL-2, IL-4, and IL-7 responses, as well as TCR-mediated activation and proliferation, of CD4+ T cells. PLA2G1B also decreased CD4+ T cell survival in vitro, likely playing a role in CD4 lymphopenia in conjunction with its induced IL-7 receptor defects. The effects on CD4+ T cell anergy could be blocked by a PLA2G1B-specific neutralizing mAb in vitro and in vivo. The PLA2G1B/gp41 pair constitutes what we believe is a new mechanism of immune dysfunction and a compelling target for boosting immune responses in HIV-infected patients.

Distinct lipid profile, low-level inflammation, and increased antioxidant defense signature in HIV-1 elite control status

HIV-1 elite controllers (EC) are a rare but heterogeneous group of HIV-1-infected individuals who can suppress viral replication in the absence of antiretroviral therapy. The mechanisms of how EC achieve undetectable viral loads remain unclear. This study aimed to investigate host plasma metabolomics and targeted plasma proteomics in a Swedish HIV-1 cohort including EC and treatment-naïve viremic progressors (VP) as well as HIV-negative individuals (HC) to get insights into EC phenotype. Metabolites belonging to antioxidant defense had higher levels in EC relative to VP, whereas inflammation markers were increased in VP compared with EC. Only four plasma proteins (CCL4, CCL7, CCL20, and NOS3) were increased in EC compared with HC, and CCL20/CCR6 axis can play an essential role in EC status. Our study suggests that low-level inflammation and oxidative stress at physiological levels could be important factors contributing to elite control phenotype.

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Increased acylcholine as unique HIV-1 positive elite controllers (EC) feature

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Physiological oxidative stress and inflammation profile in EC

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Increased in CCL4, CCL7, CCL20, and NOS3 in EC compared with HIV-ve control

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CCR6-CCL20-dependent anti-HIV mechanism can play an essential role in EC status

Identification of molecular mechanisms for achieving HIV-1 control in the absence of antiretroviral therapy

AIMS

Antiretroviral therapy (ART) controls viral replication but cannot eradicate an infected virus and restore the immune response of patients.

MATERIALS AND METHODS

The gene expression profiles of whole blood, PBMCs, CD4+ and CD8+ T cells were obtained from GSE108297. Coexpression analysis was carried out to evaluate differentially expressed genes (DEGs) between strong and weak responder HIV controllers (HICs). Enrichment analysis was used to explore the biological functions of DEGs. The key genes with common DEGs were screened using the Lasso Cox model. Then, the immune scores of HICs and HAART were calculated by ssGSEA. The content of CD4+ and CD8+ T cells, key genes were verified by flow cytometry, RT-PCR and Western blot analysis.

KEY FINDINGS

DEGs were clustered into 24 coexpression modules. DEGs related to general immune responses had the highest correlation with strong responding HICs, while DEGs mainly related to the apoptotic process had the highest correlation with weak responder HICs. The hub genes CD8A and CCT2, as well as the key genes TMEM132C and S100A9, were DEGs in HICs and HARRT. The immune score and flow cytometry showed that CD4+ and CD8+ T cells of HICs were lower than those of HARRT in whole blood. Experiments confirmed the expression of key genes in HICs and HARRT.

SIGNIFICANCE

The key genes identified in this study highlight the strong responder HICs features that to help the immune system control HIV-1 infection. These results will be useful for developing therapeutic targets.

Early exposure to broadly neutralizing antibodies may trigger a dynamical switch from progressive disease to lasting control of SHIV infection

Antiretroviral therapy (ART) for HIV-1 infection is life-long. Stopping therapy typically leads to the reignition of infection and progressive disease. In a major breakthrough, recent studies have shown that early initiation of ART can lead to sustained post-treatment control of viremia, raising hopes of long-term HIV-1 remission. ART, however, elicits post-treatment control in a small fraction of individuals treated. Strikingly, passive immunization with broadly neutralizing antibodies (bNAbs) of HIV-1 early in infection was found recently to elicit long-term control in a majority of SHIV-infected macaques, suggesting that HIV-1 remission may be more widely achievable. The mechanisms underlying the control elicited by bNAb therapy, however, remain unclear. Untreated infection typically leads to progressive disease. We hypothesized that viremic control represents an alternative but rarely realized outcome of the infection and that early bNAb therapy triggers a dynamical switch to this outcome. To test this hypothesis, we constructed a model of viral dynamics with bNAb therapy and applied it to analyse clinical data. The model fit quantitatively the complex longitudinal viral load data from macaques that achieved lasting control. The model predicted, consistently with our hypothesis, that the underlying system exhibited bistability, indicating two potential outcomes of infection. The first had high viremia, weak cytotoxic effector responses, and high effector exhaustion, marking progressive disease. The second had low viremia, strong effector responses, and low effector exhaustion, indicating lasting viremic control. Further, model predictions suggest that early bNAb therapy elicited lasting control via pleiotropic effects. bNAb therapy lowers viremia, which would also limit immune exhaustion. Simultaneously, it can improve effector stimulation via cross-presentation. Consequently, viremia may resurge post-therapy, but would encounter a primed effector population and eventually get controlled. ART suppresses viremia but does not enhance effector stimulation, explaining its limited ability to elicit post-treatment control relative to bNAb therapy.

In a remarkable advance in HIV cure research, a recent study showed that 3 weekly doses of HIV-1 broadly neutralizing antibodies (bNAbs) soon after infection kept viral levels controlled for years in most macaques treated. If translated to humans, this bNAb therapy may elicit a functional cure, or long-term remission, of HIV-1 infection, eliminating the need for life-long antiretroviral therapy (ART). How early bNAb therapy works remains unknown. Here, we elucidate the mechanism using mathematical modeling and analysis of in vivo data. We predict that early bNAb therapy suppresses viremia, which reduces exhaustion of cytotoxic effector cells, and enhances antigen uptake and effector stimulation. Collectively, these effects drive infection to lasting control. Model predictions based on these effects fit in vivo data quantitatively. ART controls viremia but does not improve effector stimulation, explaining its weaker ability to induce lasting control post-treatment. Our findings may help improve strategies for achieving functional cure of HIV-1 infection.

Blood-based inflammation biomarkers of neurocognitive impairment in people living with HIV

Inflammation in people living with HIV (PLWH) correlates with severity of HIV-associated neurocognitive disorders. The objective of this study is to identify blood-based markers of neurocognitive function in a demographic balanced cohort of PLWH. Seven neurocognitive domains were evaluated in 121 seropositive Black/African American, Non-Hispanic White, and White Hispanic men and women using computerized assessments. Associations among standardized neurocognitive function and HIV-related parameters, relevant sociodemographic variables, and inflammation-associated cytokines measured in plasma and cellular supernatants were examined using multivariate and univariate regression models. Outlier and covariate analyses were used to identify and normalize for education level, CD4 T cell count, viral load, CNS and drug abuse comorbidities, which could influence biomarker and neurocognitive function associations. Plasma levels of chemokine (C-C motif) ligand (CCL) 8 significantly associated with memory, complex attention, cognitive flexibility, psychomotor speed, executive function, and processing speed. Plasma tissue inhibitor of metalloproteinases 1 associated with the aforementioned domains except memory and processing speed. In addition, plasma interleukin-23 significantly associated with processing speed and executive function. Analysis of peripheral blood cell culture supernatants revealed no significant markers for neurocognitive function. In this cohort, CD4 T cell count and education level also significantly associated with neurocognitive function. All identified inflammatory biomarkers demonstrated a negative correlation to neurocognitive function. These cytokines have known connections to HIV pathophysiology and are potential biomarkers for neurocognitive function in PLWH with promising clinical applications.

Elite controllers and lessons learned for HIV-1 cure

Following the success of HIV-1 antiviral treatment that maintains undetectable levels of viral replication and lack of clinical progression, the design of an HIV-1 cure for patients became the next objective. The success of the treated individuals together with the identification of subjects that spontaneously control the clinical progression for long periods, such as long-term non-progressors (LTNPs) and particularly LTNP Elite Controllers (LTNP EC) have shed hope for the feasibility of a potential cure. Although a successful cure has not been attained yet, these patients have provided critical information on the mechanisms involved in the clinical control such as host genetic factors, as well as strong immune responses against the virus. Less attention has been paid to virological factors, particularly the association of the genetic variability and the control of viral infection. Considering all these studies, it has become clear that a combination of several host, immune and viral factors is needed to attain control of the viral replication control and the non-progressor clinical phenotype. Because this control can be reached through different combinations of factors, this group of individuals is not homogenous. As HIV-1 cure has been shown to be extremely difficult to achieve, a more feasible objective is the functional cure of the viral infection. After the analysis of multiple studies on the mechanisms of control in LTNP EC, we found subjects with various host protective factors and prolonged viral control. These subjects present a complete lack of evolution after more than 20-30 years of infection, stable levels of CD4+ cells (>400-500 cells/μl), a strong immune response, and no signs of clinical progression. We propose that individuals with these characteristics could have attained a functional cure of the HIV-1 infection.

Immune Control of HIV

The human immunodeficiency virus (HIV) infection of the immune cells expressing the cluster of differentiation 4 cell surface glycoprotein (CD4⁺ cells) causes progressive decline of the immune system and leads to the acquired immunodeficiency syndrome (AIDS). The ongoing global HIV/AIDS pandemic has already claimed over 35 million lives. Even after 37 years into the epidemic, neither a cure is available for the 37 million people living with HIV (PLHIV) nor is a vaccine discovered to avert the millions of new HIV infections that continue to occur each year. If left untreated, HIV infection typically progresses to AIDS and, ultimately, causes death in a majority of PLHIV. The recommended combination antiretroviral therapy (cART) suppresses virus replication and viremia, prevents or delays progression to AIDS, reduces transmission rates, and lowers HIV-associated mortality and morbidity. However, because cART does not eliminate HIV, and an enduring pool of infected resting memory CD4⁺ T cells (latent HIV reservoir) is established early on, any interruption to cART leads to a relapse of viremia and disease progression. Hence, strict adherence to a life-long cART regimen is mandatory for managing HIV infection in PLHIV. The HIV-1-specific cytotoxic T cells expressing the CD8 glycoprotein (CD8⁺ CTL) limit the virus replication in vivo by recognizing the viral antigens presented by human leukocyte antigen (HLA) class I molecules on the infected cell surface and killing those cells. Nevertheless, CTLs fail to durably control HIV-1 replication and disease progression in the absence of cART. Intriguingly, <1% of cART-naive HIV-infected individuals called elite controllers/HIV controllers (HCs) exhibit the core features that define a HIV-1 "functional cure" outcome in the absence of cART: durable viral suppression to below the limit of detection, long-term non-progression to AIDS, and absence of viral transmission. Robust HIV-1-specific CTL responses and prevalence of protective HLA alleles associated with enduring HIV-1 control have been linked to the HC phenotype. An understanding of the molecular mechanisms underlying the CTL-mediated suppression of HIV-1 replication and disease progression in HCs carrying specific protective HLA alleles may yield promising insights towards advancing the research on HIV cure and prophylactic HIV vaccine.