Integrated Assessment of Viral Transcription, Antigen Presentation, and CD8+ T Cell Function Reveals Multiple Limitations of Class I-Selective Histone Deacetylase Inhibitors during HIV-1 Latency Reversal.

Clinical trials investigating histone deacetylase inhibitors (HDACi) to reverse HIV-1 latency aim to expose reservoirs in antiretroviral (ARV)-treated individuals to clearance by immune effectors, yet have not driven measurable reductions in the frequencies of infected cells. We therefore investigated the effects of the class I-selective HDACi nanatinostat and romidepsin on various blocks to latency reversal and elimination, including viral splicing, antigen presentation, and CD8+ T cell function. In ex vivo CD4+ T cells from ARV-suppressed individuals, both HDACi significantly induced viral transcription, but not splicing nor supernatant HIV-1 RNA. In an HIV-1 latency model using autologous CD8+ T cell clones as biosensors of antigen presentation, neither HDACi-treated CD4+ T cell condition induced clone degranulation. Both HDACi also impaired the function of primary CD8+ T cells in viral inhibition assays, with nanatinostat causing less impairment. These findings suggest that spliced or cell-free HIV-1 RNAs are more indicative of antigen expression than unspliced HIV-RNAs and may help to explain the limited abilities of HDACi to generate CD8+ T cell targets in vivoIMPORTANCE Antiretroviral (ARV) drug regimens suppress HIV-1 replication but are unable to cure infection. This leaves people living with HIV-1 burdened by a lifelong commitment to expensive daily medication. Furthermore, it has become clear that ARV therapy does not fully restore health, leaving individuals at elevated risk for cardiovascular disease, certain types of cancers, and neurocognitive disorders, as well as leaving them exposed to stigma. Efforts are therefore under way to develop therapies capable of curing infection. A key focus of these efforts has been on a class of drugs called histone deacetylase inhibitors (HDACi), which have the potential of exposing hidden reservoirs of HIV-1 to elimination by the immune system. Unfortunately, clinical trial results with HDACi have thus far been disappointing. In the current study, we integrate a number of experimental approaches to build a model that provides insights into the limited activity of HDACi in clinical trials and offers direction for future approaches.

HIV Subtype and Nef-Mediated Immune Evasion Function Correlate with Viral Reservoir Size in Early-Treated Individuals.

The HIV accessory protein Nef modulates key immune evasion and pathogenic functions, and its encoding gene region exhibits high sequence diversity. Given the recent identification of early HIV-specific adaptive immune responses as novel correlates of HIV reservoir size, we hypothesized that viral factors that facilitate the evasion of such responses-namely, Nef genetic and functional diversity-might also influence reservoir establishment and/or persistence. We isolated baseline plasma HIV RNA-derived nef clones from 30 acute/early-infected individuals who participated in a clinical trial of early combination antiretroviral therapy (cART) (<6 months following infection) and assessed each Nef clone's ability to downregulate CD4 and human leukocyte antigen (HLA) class I in vitro We then explored the relationships between baseline clinical, immunological, and virological characteristics and the HIV reservoir size measured 48 weeks following initiation of suppressive cART (where the reservoir size was quantified in terms of the proviral DNA loads as well as the levels of replication-competent HIV in CD4+ T cells). Maximal within-host Nef-mediated downregulation of HLA, but not CD4, correlated positively with post-cART proviral DNA levels (Spearman's R = 0.61, P = 0.0004) and replication-competent reservoir sizes (Spearman's R = 0.36, P = 0.056) in univariable analyses. Furthermore, the Nef-mediated HLA downregulation function was retained in final multivariable models adjusting for established clinical and immunological correlates of reservoir size. Finally, HIV subtype B-infected persons (n = 25) harbored significantly larger viral reservoirs than non-subtype B-infected persons (2 infected with subtype CRF01_AE and 3 infected with subtype G). Our results highlight a potentially important role of viral factors-in particular, HIV subtype and accessory protein function-in modulating viral reservoir establishment and persistence.IMPORTANCE While combination antiretroviral therapies (cART) have transformed HIV infection into a chronic manageable condition, they do not act upon the latent HIV reservoir and are therefore not curative. As HIV cure or remission should be more readily achievable in individuals with smaller HIV reservoirs, achieving a deeper understanding of the clinical, immunological, and virological determinants of reservoir size is critical to eradication efforts. We performed a post hoc analysis of 30 participants of a clinical trial of early cART who had previously been assessed in detail for their clinical, immunological, and reservoir size characteristics. We observed that the HIV subtype and autologous Nef-mediated HLA downregulation function correlated with the viral reservoir size measured approximately 1 year post-cART initiation. Our findings highlight virological characteristics-both genetic and functional-as possible novel determinants of HIV reservoir establishment and persistence.

Increased HIV-specific CD8+ T-cell cytotoxic potential in HIV elite controllers is associated with T-bet expression.

Recent data suggest that CD8+ T-cell effector activity is an important component in the control of HIV replication in elite controllers (ECs). One critical element of CD8+ T-cell effector function and differentiation is the T-box transcription factor T-bet. In the present study, we assessed T-bet expression, together with the effector proteins perforin, granzyme A (Grz A), granzyme B (Grz B), and granulysin, in HIV-specific CD8+ T cells from ECs (n = 20), chronically infected progressors (CPs; n = 18), and highly active antiretroviral therapy (HAART)-suppressed individuals (n = 19). Compared with the other cohort groups, HIV-specific CD8+ T cells among ECs demonstrated a superior ability to express perforin and Grz B, but with no detectable difference in the levels of Grz A or granulysin. We also observed higher levels of T-bet in HIV-specific CD8+ T cells from ECs, with an ensuing positive correlation between T-bet and levels of both perforin and Grz B. Moreover, HIV-specific CD8+ T cells in ECs up-regulated T-bet to a greater extent than CPs after in vitro expansion, with concomitant up-regulation of perforin and Grz B. These results suggest that T-bet may play an important role in driving effector function, and its modulation may lead to enhanced effector activity against HIV.

Circulating endothelial progenitor cell levels are not reduced in HIV-infected men.

Reduced levels of endothelial progenitor cells (EPCs) have been associated with increased cardiovascular (CV) risk, but limited data are available on EPC levels in the human immunodeficiency virus (HIV)-infected population. EPCs (CD45(dim)/CD34(+)/kinase domain receptor(+)) from 36 HIV-uninfected and 30 antiretroviral therapy-naive HIV-infected men without known CV risk factors were enumerated using flow cytometry. The mean EPC levels (± standard error of the mean) were 1.4 ± 0.5 cells/µL in the HIV-infected group and 3.7 ± 2.2 cells/µL in the control group (P = .92). EPC levels were not associated with disease parameters, such as CD4 cell count or viral load. Reductions in EPC levels do not seem to explain the increased risk of CV disease among HIV-infected men.

Perforin expression directly ex vivo by HIV-specific CD8 T-cells is a correlate of HIV elite control.

Many immune correlates of CD8(+) T-cell-mediated control of HIV replication, including polyfunctionality, proliferative ability, and inhibitory receptor expression, have been discovered. However, no functional correlates using ex vivo cells have been identified with the known ability to cause the direct elimination of HIV-infected cells. We have recently discovered the ability of human CD8(+) T-cells to rapidly upregulate perforin--an essential molecule for cell-mediated cytotoxicity--following antigen-specific stimulation. Here, we examined perforin expression capability in a large cross-sectional cohort of chronically HIV-infected individuals with varying levels of viral load: elite controllers (n = 35), viremic controllers (n = 29), chronic progressors (n = 27), and viremic nonprogressors (n = 6). Using polychromatic flow cytometry and standard intracellular cytokine staining assays, we measured perforin upregulation, cytokine production, and degranulation following stimulation with overlapping peptide pools encompassing all proteins of HIV. We observed that HIV-specific CD8(+) T-cells from elite controllers consistently display an enhanced ability to express perforin directly ex vivo compared to all other groups. This ability is not restricted to protective HLA-B haplotypes, does not require proliferation or the addition of exogenous factors, is not restored by HAART, and primarily originates from effector CD8(+) T-cells with otherwise limited functional capability. Notably, we found an inverse relationship between HIV-specific perforin expression and viral load. Thus, the capability of HIV-specific CD8(+) T-cells to rapidly express perforin defines a novel correlate of control in HIV infection.

HIV-specific IL-21 producing CD4+ T cells are induced in acute and chronic progressive HIV infection and are associated with relative viral control.

We examined the role of CD4(+) T cell IL-21 production in viral control of HIV infection. HIV-infected individuals had greater circulating IL-21-producing CD4(+) T cells in blood compared with uninfected volunteers. HIV-specific IL-21-producing CD4(+) T cells were detected in blood during untreated acute and chronic HIV infection, and elevated frequencies of these cells correlated with relative viral control. These cells had an effector memory or end effector phenotype and expressed CXCR5. HIV-specific CD8(+) T cells exhibited high levels of IL-21R, indicating sensitivity to IL-21. Low or aviremic long-term nonprogressors, however, showed absent or low HIV-specific IL-21 CD4(+) T cells, but more easily detectable HIV-specific IL-2-producing CD4(+) T cells, suggesting changing requirements for particular gamma-chain cytokines depending on Ag abundance. Thus, IL-21-producing CD4(+) T cells are induced in viremic HIV infection and likely contribute to viral control by affecting CD8(+) T cell maintenance.

Parasitic disease screening among HIV patients from endemic countries in a Toronto clinic.

BACKGROUND: Many North American-based HIV patients originate from parasitic disease-endemic regions. Strongyloidiasis, schistosomiasis and filariasis are important due to their wide distribution and potential for severe morbidity. OBJECTIVES: To determine the prevalence, as determined by serological screening, of strongyloidiasis, schistosomiasis and filariasis among patients in an HIV-focused, primary care practice in Toronto, Ontario. A secondary objective was to determine factors associated with positive serological screens. METHODS: A retrospective review of electronic patient records was conducted. Results of serological screens for parasites and relevant laboratory data were collected. RESULTS: Ninety-seven patients were identified. The patients' mean CD4(+) count was 0.45×10(9)/L, median viral load was undetectable and 68% were on highly active antiretroviral therapy (HAART). Most originated from Africa (37%) and South America (35%). Of the 97 patients, 10.4% and 8.3% had positive or equivocal screening results for strongyloidiasis, respectively, 7.4% and 4.2% had positive or equivocal screening results for schistosomiasis and 5.5% and 6.8% had positive or equivocal screens for filariasis. Persons with positive parasitic serologies were more often female (28% versus 9%, P=0.03), younger in age (36 versus 43 years of age, P<0.01), had been in Canada for a shorter duration (5 versus 12 years, P<0.0001) and had a higher viral load (10,990 copies/mL versus <50 copies/mL, P <0.001). All patients were asymptomatic. Eosinophilia was not associated with positive screening results. CONCLUSIONS: Using symptoms and eosinophilia to identify parasitic infection was not reliable. Screening for strongyloidiasis and schistosomiasis among patients with HIV from parasite-endemic countries is simple and benign, and may prevent future complications. The clinical benefits of screening for filariasis require further elucidation, but this practice appears to be the least warranted. BACKGROUND: Many North American-based HIV patients originate from parasitic disease-endemic regions. Strongyloidiasis, schistosomiasis and filariasis are important due to their wide distribution and potential for severe morbidity. OBJECTIVES: To determine the prevalence, as determined by serological screening, of strongyloidiasis, schistosomiasis and filariasis among patients in an HIV-focused, primary care practice in Toronto, Ontario. A secondary objective was to determine factors associated with positive serological screens. METHODS: A retrospective review of electronic patient records was conducted. Results of serological screens for parasites and relevant laboratory data were collected. RESULTS: Ninety-seven patients were identified. The patients' mean CD4+ count was 0.45×109/L, median viral load was undetectable and 68% were on highly active antiretroviral therapy (HAART). Most originated from Africa (37%) and South America (35%). Of the 97 patients, 10.4% and 8.3% had positive or equivocal screening results for strongyloidiasis, respectively, 7.4% and 4.2% had positive or equivocal screening results for schistosomiasis and 5.5% and 6.8% had positive or equivocal screens for filariasis. Persons with positive parasitic serologies were more often female (28% versus 9%, P=0.03), younger in age (36 versus 43 years of age, P<0.01), had been in Canada for a shorter duration (5 versus 12 years, P<0.0001) and had a higher viral load (10,990 copies/mL versus <50 copies/mL, P <0.001). All patients were asymptomatic. Eosinophilia was not associated with positive screening results. CONCLUSIONS: Using symptoms and eosinophilia to identify parasitic infection was not reliable. Screening for strongyloidiasis and schistosomiasis among patients with HIV from parasite-endemic countries is simple and benign, and may prevent future complications. The clinical benefits of screening for filariasis require further elucidation, but this practice appears to be the least warranted.

HISTORIQUE: De nombreux patients atteints du VIH qui vivent en Amérique du Nord proviennent de régions où les parasitoses sont endémiques. La strongyloïdose, la schistosomiase et la filariose sont importantes, en raison de leur vaste répartition géographique et de leur potentiel de grave morbidité. OBJECTIFS: Déterminer la prévalence, établie par dépistage sérologique, des strongyloïdoses, des schistosomiases et des filarioses chez les patients d'un cabinet de soins primaires axés sur le VIH de Toronto, en Ontario. Un objectif secondaire consistait à déterminer les facteurs associés à des dépistages sérologiques positifs. MÉTHODOLOGIE: Les chercheurs ont procédé à une analyse rétrospective des dossiers électroniques des patients. Ils ont colligé les résultats des tests de dépistage sérologiques des parasites et les données de laboratoire pertinentes. RÉSULTATS: Les chercheurs ont repéré 97 patients, dont la numération de CD4 moyenne s'élevait à 0,45×109/L, dont la charge virale moyenne était indétectable et dont 68 % prenaient un traitement antirétroviral hautement actif (HAART). La plupart étaient originaires de l'Afrique (37 %) et de l'Amérique du Sud (35 %). Parmi les 97 patients, 10,4 % et 8,3 % avaient respectivement obtenu des résultats de dépistage positifs ou équivoques de strongyloïdose, 7,4 % et 4,2 %, des résultats de dépistage positifs ou équivoques de schistosomiase et 5,5 % et 6,8 %, des résultats de dépistage positifs ou équivoques de filariose. Les personnes obtenant une sérologie parasitaire positive étaient surtout des femmes (28 % par rapport à 9 %, P=0,03), étaient plus jeunes (36 ans par rapport à 43, P<0,01), étaient au Canada depuis moins longtemps (5 ans par rapport à 12, P<0,0001) et avaient une charge virale plus élevée (10 990 copies/mL par rapport à moins de 50 copies/mL, P<0,001). Tous les patients étaient asymptomatiques. Les éosinophiles ne s'associaient pas à des résultats de dépistage positifs. CONCLUSIONS: L'observation des symptômes et des éosinophiles n'était pas fiable pour diagnostiquer une infection parasitaire. Le dépistage de la strongyloïdose et de la schistosomiase chez les patients atteints du VIH provenant de pays endémiques aux parasites est à la fois simple et anodin, sans compter qu'il peut prévenir de futures complications. Il faudra mieux préciser les bienfaits cliniques du dépistage de la filariose, mais cette pratique semble la moins justifiée.

Randomized, Blinded, Placebo-Controlled Trial of De Simone Formulation Probiotic During HIV-Associated Suboptimal CD4+ T Cell Recovery.

OBJECTIVE: To assess whether probiotic supplementation may reduce disease-linked systemic immune activation in people living with HIV with the immunologic nonresponder phenotype. DESIGN: Phase 2b, randomized, double-blind, placebo-controlled pilot trial. METHODS: HIV-positive individuals with blood CD4+ T-cell counts <350/mm3 despite viral suppression were randomized to 2:1 to receive De Simone Formulation Probiotic (DSFP; "Visbiome" commercially) or placebo for 48 weeks; target enrollment was 36 patients. The primary endpoint was the change in blood CD8+ T-cell coexpression of human leukocyte antigen-DR isotype and CD38 ("CD8 activation"). Secondary endpoints included biomarkers of inflammation, immune reconstitution, bacterial translocation, and gut permeability. Adjusted linear regression and linear mixed regression methods evaluated the differences between study arms from baseline to week 48. Study monitoring was performed by the CIHR Canadian HIV Trials Network Data Safety Monitoring Committee. RESULTS: Nineteen patients received DSFP, whereas 10 received placebo. One probiotic arm patient withdrew early. Blood CD8 activation increased 0.82 percentage points (pp) in the probiotic arm (95% confidence interval: -1.23 to 2.87;) and decreased by 2.06 pp in the placebo arm (-4.81 to 0.70; between arms P = 0.097). CD4+ T-cell activation (%HLA-DR+) decreased in the placebo arm [-3.79 pp (-7.32 to -0.26)] but increased in the probiotic arm [1.64 (-0.98 to 4.26); between arms P = 0.018]. No differences were observed in plasma or urine biomarkers of inflammation or microbial translocation. CONCLUSIONS: Blood immune activation markers in immunologic nonresponder individuals on effective antiretroviral treatment were not reduced by supplementation with DSFP; CD4+ T-cell activation may have been increased.

Activation and gut-homing of peripheral T cells in HIV immunologic non-responders despite long term viral suppression.

OBJECTIVE: Serious non-AIDS disease events (SNAE) are experienced disproportionately by immunologic non-responders (INRs), HIV-infected individuals who do not restore CD4 T cells in blood despite effective viral suppression. We aimed to characterize the inflammatory biomarker profile of the INR phenotype. METHODS: Blinded cross-sectional cohort study comparing markers of immune activation and gut homing between INR and non-INR individuals. HIV-positive participants had HIV RNA suppression on antiretroviral therapy and were categorized as either INR (N = 36) or Clinical Responders ("CR"; CD4>350/mm3; N = 47). 18 HIV-negative comparator individuals were included. Cellular markers were assessed by flow cytometry, with soluble markers assessed by ELISA and LC/MS-MS. Multivariable linear regression models estimated the association between INR phenotype and markers, adjusting for age, sex, duration of ART, and recent infection/vaccination. RESULTS: INR participants demonstrated a reduced CD4/CD8 ratio (p<0.001), 35% more CD8 activation (p = 0.02), 36% greater α4ß7+ CD4 T cells (p<0.01), 54% more HLA-DR+ CD4 T cells (p<0.001), and 20% higher plasma VCAM (p<0.01) compared to CRs. The INR phenotype was not associated with levels of Kyn/Trp, CRP, TNF, IFNγ, IL-8, IL-6, sCD14, D-Dimer, I-FABP, MCP-1, ICAM or CD8%HLA-DR+. CONCLUSIONS: Peripheral CD4 non-recovery during long-term treated HIV infection is characterized by elevated CD8 activation and CD4 gut homing. Gut-focused interventions may be warranted in the INR context, and CD8 activation may serve as a surrogate endpoint for clinical interventions.

The Dietary Inflammatory Index Is Not Associated With Gut Permeability or Biomarkers of Systemic Inflammation in HIV Immunologic Non-responders.

Immunologic non-responders (INRs) are a subset of individuals living with HIV who have suboptimal blood CD4+ T cell recovery despite effective antiretroviral therapy (ART). They are at an increased risk of serious non-AIDS co-morbidities and death, and demonstrate enhanced systemic immune activation. In other populations diet has been correlated with markers of systemic inflammation through the Diet Inflammatory Index (DII), but this association has not been studied in persons living with HIV (PLWH). Blood was collected from 28 INR PLWH with a blood CD4+ T cell count <350/µL despite ≥2 years of effective ART. Participants completed a Canadian Diet History Questionnaire, and their responses were used to calculate the DII. Plasma inflammatory markers (IFNγ, TNF, IL-6, sVCAM, D-dimer, sCD14 and CRP) were assayed by ELISA, cellular immune activation (HLA-DR and CD38 on CD4+ and CD8+ T cells) was quantified using flow cytometry, and small bowel permeability assessed by calculation of the urine LacMan ratio after drinking a mix of lactulose and mannitol. Participants were a median age of 57 years, had been on effective ART for 15 years, and the median DII was -1.91 (range of -3.78 to +2.23). No correlation was observed between DII and plasma markers of inflammation, levels of T cell activation, gut permeability, or the biomarker of bacterial translocation sCD14. Self-reported alcohol intake, a potential confounder of the relationship between diet and inflammatory biomarkers, was also not associated with systemic inflammation or gut permeability. Our findings suggest that other mechanisms, rather than diet, are likely to be the major driver of systemic inflammation in INR individuals.

BCL-2 antagonism sensitizes cytotoxic T cell-resistant HIV reservoirs to elimination ex vivo.

Curing HIV infection will require the elimination of a reservoir of infected CD4+ T cells that persists despite HIV-specific cytotoxic T cell (CTL) responses. Although viral latency is a critical factor in this persistence, recent evidence also suggests a role for intrinsic resistance of reservoir-harboring cells to CTL killing. This resistance may have contributed to negative outcomes of clinical trials, where pharmacologic latency reversal has thus far failed to drive reductions in HIV reservoirs. Through transcriptional profiling, we herein identified overexpression of the prosurvival factor B cell lymphoma 2 (BCL-2) as a distinguishing feature of CD4+ T cells that survived CTL killing. We show that the inducible HIV reservoir was disproportionately present in BCL-2hi subsets in ex vivo CD4+ T cells. Treatment with the BCL-2 antagonist ABT-199 was not sufficient to drive reductions in ex vivo viral reservoirs when tested either alone or with a latency-reversing agent (LRA). However, the triple combination of strong LRAs, HIV-specific T cells, and a BCL-2 antagonist uniquely enabled the depletion of ex vivo viral reservoirs. Our results provide rationale for novel therapeutic approaches targeting HIV cure and, more generally, suggest consideration of BCL-2 antagonism as a means of enhancing CTL immunotherapy in other settings, such as cancer.

Virus-specific interleukin-17-producing CD4+ T cells are detectable in early human immunodeficiency virus type 1 infection.

T(H)-17 cells have been shown to play a role in bacterial defense, acute inflammation, and autoimmunity. We examined the role of interleukin 17 (IL-17) production in human immunodeficiency virus type 1 (HIV-1) infection. Both HIV-1- and cytomegalovirus (CMV)-specific IL-17-producing CD4(+) T cells were detectable in early HIV-1 infection but were reduced to nondetectable levels in chronic and nonprogressive HIV-1 infection. IL-17-producing CMV-specific cells were not detected in blood from HIV-1-uninfected normal volunteers. Virus-specific T(H)-17 cells could coexpress other cytokines and could express CCR4 or CXCR3. Although the etiology of these cells has yet to be established, we propose that microbial translocation may induce them.

Effectiveness and tolerability of oral administration of low-dose salmon oil to HIV patients with HAART-associated dyslipidemia.

PURPOSE: To assess the effectiveness of low-dose salmon oil for the treatment of highly active antiretroviral therapy (HAART)-induced dyslipidemia in HIV-infected patients. METHOD: Randomized, open-label, parallel and crossover, multicenter study. Patients received 1 g salmon oil tid for 24 weeks (SO-24) or no additional treatment for 12 weeks and salmon oil for weeks 12 to 24 (CT-SO). The primary outcome measure was the change in triglyceride (TG) levels. RESULTS: Fifty-eight patients completed the study (26 in SO-24; 32 in CT-SO). After 12 weeks, the SO-24 group experienced a mean TG reduction of 1.1 mmol/L, compared to an increase of 0.3 mmol/L for the CT-SO group (p = .040). When CT-SO patients were crossed over to salmon oil treatment, mean TG decreased by 0.7 mmol/L (p = .052). Concomitant use of fibrates, statins, or both were reported by 16 (27.6%), 10 (17.2%), and 8 (13.8%), respectively. Multivariate analysis showed that salmon oil produced a significant decrease in TG levels independent of other lipid-lowering medications (p = .022). There were 26 predominately mild treatment-emergent (antiretroviral or salmon oil) nonserious adverse events reported by 22 (33.3%) patients. CONCLUSION: Low-dose salmon oil (3 g/day) is effective and well-tolerated in reducing TG levels in HIV-infected patients receiving HAART.

Randomized controlled trial of once-daily tenofovir, lamivudine, and lopinavir/ritonavir versus remaining on the same regimen in virologically suppressed HIV-infected patients on their first PI-containing HAART regimen.

PURPOSE: To assess the effects of switching to once-daily (QD) lopinavir/ritonavir (LPV/r)-based combination therapy in HIV-infected patients who are virologically suppressed (HIV viral load <50 copies/mL) on their first protease inhibitor (PI)-containing regimen. METHOD: In this 48-week, prospective, open-label, randomized study, patients were either switched to once-daily LPV/r, tenofovir (TDF), and lamivudine (3TC) (QD arm) or remained on their existing regimen (control arm). The primary endpoint of the study was the proportion of patients maintaining virologic suppression following 48 weeks of treatment. RESULTS: Fifty and 22 patients were randomized to the QD and control arms, respectively. At week 48, there was no significant difference in virological suppression between the QD and control arms using intent-to-treat (missing = failure) analysis (p = .44). There was no significant difference in discontinuation rates between the two arms (p = .66). Significantly more patients randomized to the QD arm reported gastrointestinal adverse events compared with the control arm (p = .009). There were no study drug-related serious adverse events. CONCLUSION: For patients who are already virologically suppressed on their first PI-containing regimen, switching to a QD regimen of TDF+3TC+LPV/r resulted in similar rates of virologic suppression when compared with staying on existing therapy.

Why can't the immune system control HIV-1? Defining HIV-1-specific CD4+ T cell immunity in order to develop strategies to enhance viral immunity.

Globally, at least 60 million people have been infected with the human immunodeficiency virus type 1 (HIV-1), the majority of whom will develop the acquired immunodeficiency syndrome (AIDS) leading to tremendous morbidity and the mortality. Understanding the immunopathogenesis of AIDS and the immune correlates of viral protection are necessary to develop effective vaccines and immunotherapies. A major focus of our laboratory has been to understand the CD4+ T cell immune response directed against HIV- 1, and to determine mechanisms of T cell dysfunction that lead to viral escape. In addition, we are interested in evaluating the TNF-TNFR family members as potential molecular adjuvants that could be incorporated into vaccines which could be used to further boost T cell immunogenicity in healthy or HIV-1-infected individuals, as many of these molecules have been shown to replace the functions of CD4+ T cell help.

Loss of the signaling adaptor TRAF1 causes CD8+ T cell dysregulation during human and murine chronic infection.

The signaling adaptor TNFR-associated factor 1 (TRAF1) is specifically lost from virus-specific CD8 T cells during the chronic phase of infection with HIV in humans or lymphocytic choriomeningitis virus (LCMV) clone 13 in mice. In contrast, TRAF1 is maintained at higher levels in virus-specific T cells of HIV controllers or after acute LCMV infection. TRAF1 expression negatively correlates with programmed death 1 expression and HIV load and knockdown of TRAF1 in CD8 T cells from viral controllers results in decreased HIV suppression ex vivo. Consistent with the desensitization of the TRAF1-binding co-stimulatory receptor 4-1BB, 4-1BBL-deficient mice have defects in viral control early, but not late, in chronic infection. TGFß induces the posttranslational loss of TRAF1, whereas IL-7 restores TRAF1 levels. A combination treatment with IL-7 and agonist anti-4-1BB antibody at 3 wk after LCMV clone 13 infection expands T cells and reduces viral load in a TRAF1-dependent manner. Moreover, transfer of TRAF1(+) but not TRAF1(-) memory T cells at the chronic stage of infection reduces viral load. These findings identify TRAF1 as a potential biomarker of HIV-specific CD8 T cell fitness during the chronic phase of disease and a target for therapy.

Early changes in T-cell activation predict antiretroviral success in salvage therapy of HIV infection.

OBJECTIVE: Because effective antiretroviral therapy (ART) reduces immune activation, we hypothesize that early changes in immune activation are associated with subsequent virologic response to therapy. DESIGN: Observational cohort study. SETTING: Institutional HIV clinic. SUBJECTS: Thirty-four adult HIV patients with virologic failure on their current antiretroviral regimen. INTERVENTION: Change to salvage regimen selected by patient's physician. MAIN OUTCOME MEASURES: Measures of immune activation at baseline and at 2, 4, 8, and 24 weeks after enrollment. Data were analyzed by proportional hazards (PH) models. RESULTS: PH models showed that reductions between baseline and week 2 in expression of CD38 (P = 0.02) or CD95 (P = 0.02) on CD4 T cells were associated with increased likelihood of achieving virologic suppression. Kaplan-Meier analysis demonstrated that patients who had reductions within the first 2 weeks of therapy in CD4 T-cell expression of CD38 (P = 0.003) or CD95 (P = 0.08) were more likely to achieve viral suppression than those who did not. CONCLUSIONS: Reduced CD4 T-cell expression of CD38 and CD95 occurring within 2 weeks of salvage therapy is associated with subsequent viral suppression. Monitoring CD38 and CD95 may allow earlier assessment of the response to ART.

The role of cytokines which signal through the common gamma chain cytokine receptor in the reversal of HIV specific CD4(+) and CD8(+) T cell anergy.

BACKGROUND: HIV specific T cells are putatively anergic in vivo. IL-2, a member of a class of cytokines that binds to receptors containing the common gamma chain (gammac) has been shown to reverse anergy. We examined the role of gammac cytokines in reversing HIV specific T cell anergy. METHODS: PBMC from untreated HIV-infected individuals were briefly exposed to a panel of gammac cytokines, and frequencies of gag specific T cells were enumerated by intracellular IFN-gamma flow cytometry. RESULTS: Of the gammac cytokines, brief exposure to IL-2, IL-15, or combined IL-15/IL-7 significantly enhanced (range 2-7 fold) the CD4(+) and CD8(+) T cell IFN-gamma responses to HIV gag, with IL-15 giving the greatest enhancement. The effects of cytokines were not due to enhanced proliferation of pre-existing antigen specific cells, but were due to a combination of enhanced cytokine production from antigen specific T cells plus activation of non-epitope specific T cells. CONCLUSIONS: These observations support the notion that a significant number of HIV specific T cells are circulating in an anergic state. IL-2, IL-7 and particularly IL-15 as an immune modulator to reverse HIV-1 specific T cell anergy should be investigated, with the caveat that non-specific activation of T cells may also be induced.

Impact of HIV on cell survival and antiviral activity of plasmacytoid dendritic cells.

Plasmacytoid dendritic cells (pDCs) are important mediators of innate immunity that act mainly through secretion of interferon (IFN)-alpha. Previous studies have found that these cells can suppress HIV in vitro; additionally, pDCs have been shown to be severely reduced in the peripheral blood of HIV-infected individuals. In the present study, we sought to determine the ability of pDCs to directly suppress viral replication ex vivo and to delineate the potential mechanisms whereby pDCs are depleted in HIV-infected individuals. We demonstrate that activated pDCs strongly suppress HIV replication in autologous CD4(+) T cells via a mechanism involving IFN-alpha as well as other antiviral factors. Of note, unstimulated pDCs from infected individuals who maintain low levels of plasma viremia without antiretroviral therapy were able to suppress HIV ex vivo via a mechanism requiring cell-to-cell contact. Our data also demonstrate that death of pDCs by both apoptosis and necrosis is induced by fusion of HIV with pDCs. Taken together, our data suggest that pDCs play an important role in the control of HIV replication and that high levels of viral replication in vivo are associated with pDC cell death via apoptosis and necrosis. Elucidation of the mechanism by which pDCs suppress HIV replication in vivo may have clinically relevant implications for future therapeutic strategies.