Ronald J. Bosch

Effect of Early versus Deferred Antiretroviral Therapy for HIV on Survival

BACKGROUND The optimal time for the initiation of antiretroviral therapy for asymptomatic patients with human immunodeficiency virus (HIV) infection is uncertain. METHODS We conducted two parallel analyses involving a total of 17,517 asymptomatic patients with HIV infection in the United States and Canada who received medical care during the period from 1996 through 2005. None of the patients had undergone previous antiretroviral therapy. In each group, we stratified the patients according to the CD4+ count (351 to 500 cells per cubic millimeter or >500 cells per cubic millimeter) at the initiation of antiretroviral therapy. In each group, we compared the relative risk of death for patients who initiated therapy when the CD4+ count was above each of the two thresholds of interest (early-therapy group) with that of patients who deferred therapy until the CD4+ count fell below these thresholds (deferred-therapy group). RESULTS In the first analysis, which involved 8362 patients, 2084 (25%) initiated therapy at a CD4+ count of 351 to 500 cells per cubic millimeter, and 6278 (75%) deferred therapy. After adjustment for calendar year, cohort of patients, and demographic and clinical characteristics, among patients in the deferred-therapy group there was an increase in the risk of death of 69%, as compared with that in the early-therapy group (relative risk in the deferred-therapy group, 1.69; 95% confidence interval [CI], 1.26 to 2.26; P<0.001). In the second analysis involving 9155 patients, 2220 (24%) initiated therapy at a CD4+ count of more than 500 cells per cubic millimeter and 6935 (76%) deferred therapy. Among patients in the deferred-therapy group, there was an increase in the risk of death of 94% (relative risk, 1.94; 95% CI, 1.37 to 2.79; P<0.001). CONCLUSIONS The early initiation of antiretroviral therapy before the CD4+ count fell below two prespecified thresholds significantly improved survival, as compared with deferred therapy.

Administration of vorinostat disrupts HIV-1 latency in patients on antiretroviral therapy

Despite antiretroviral therapy, proviral latency of human immunodeficiency virus type 1 (HIV-1) remains a principal obstacle to curing the infection. Inducing the expression of latent genomes within resting CD4+ T cells is the primary strategy to clear this reservoir. Although histone deacetylase inhibitors such as suberoylanilide hydroxamic acid (also known as vorinostat, VOR) can disrupt HIV-1 latency in vitro, the utility of this approach has never been directly proven in a translational clinical study of HIV-infected patients. Here we isolated the circulating resting CD4+ T cells of patients in whom viraemia was fully suppressed by antiretroviral therapy, and directly studied the effect of VOR on this latent reservoir. In each of eight patients, a single dose of VOR increased both biomarkers of cellular acetylation, and simultaneously induced an increase in HIV RNA expression in resting CD4+ cells (mean increase, 4.8-fold). This demonstrates that a molecular mechanism known to enforce HIV latency can be therapeutically targeted in humans, provides proof-of-concept for histone deacetylase inhibitors as a therapeutic class, and defines a precise approach to test novel strategies to attack and eradicate latent HIV infection directly.

Depletion of latent HIV-1 infection in vivo: a proof-of-concept study

BACKGROUND Persistent infection in resting CD4+ T cells prevents eradication of HIV-1. Since the chromatin remodeling enzyme histone deacetylase 1 (HDAC1) maintains latency of integrated HIV, we tested the ability of the HDAC inhibitor valproic acid to deplete persistent, latent infection in resting CD4+ T cells. PROCEDURES We did a proof-of-concept study in four volunteers infected with HIV and on highly-active antiretroviral therapy (HAART). After intensifying the effect of HAART with subcutaneous enfuvirtide 90 mug twice daily for 4-6 weeks to prevent the spread of HIV, we added oral valproic acid 500-750 mg twice daily to their treatment regimen for 3 months. We quantified latent infection of resting CD4+ T cells before and after augmented treatment by limiting-dilution culture of resting CD4+ T cells after ex-vivo activation. FINDINGS The frequency of resting cell infection was stable before addition of enfuvirtide and valproic acid, but declined thereafter. This decline was significant in three of four patients (mean reduction 75%, range 68% to >84%). Patients had slight reactions to enfuvirtide at the injection site, but otherwise tolerated treatment well. INTERPRETATION Combination therapy with an HDAC inhibitor and intensified HAART safely accelerates clearance of HIV from resting CD4+ T cells in vivo, suggesting a new and practical approach to eliminate HIV infection in this persistent reservoir. This finding, though not definitive, suggests that new approaches will allow the cure of HIV in the future.

The prevalence and incidence of neurocognitive impairment in the HAART era.

Objectives:HAART suppresses HIV viral replication and restores immune function. The effects of HAART on neurological disease are less well understood. The aim of this study was to assess the prevalence and incidence of neurocognitive impairment in individuals who initiated HAART as part of an AIDS clinical trial. Design:A prospective cohort study of HIV-positive patients enrolled in randomized antiretroviral trials, the AIDS Clinical Trials Group (ACTG) Longitudinal Linked Randomized Trials (ALLRT) study. Methods:We examined the association between baseline and demographic characteristics and neurocognitive impairment among 1160 subjects enrolled in the ALLRT study. Results:A history of immunosuppression (nadir CD4 cell count < 200 cells/μl) was associated with an increase in prevalent neurocognitive impairment. There were no significant virological and immunological predictors of incident neurocognitive impairment. Current immune status (low CD4 cell count) was associated with sustained prevalent impairment. Conclusion:The association of previous advanced immunosuppression with prevalent and sustained impairment suggests that there is a non-reversible component of neural injury that tracks with a history of disease progression. The association of sustained impairment with worse current immune status (low CD4 cell count) suggests that restoring immunocompetence increases the likelihood of neurocognitive recovery. Finally, the lack of association between incident neurocognitive impairment and virological and immunological indicators implies that neural injury continues in some patients regardless of the success of antiretroviral therapy on these laboratory measures.

Sex differences in the Toll-like receptor–mediated response of plasmacytoid dendritic cells to HIV-1

Manifestations of viral infections can differ between women and men, and marked sex differences have been described in the course of HIV-1 disease. HIV-1–infected women tend to have lower viral loads early in HIV-1 infection but progress faster to AIDS for a given viral load than men. Here we show substantial sex differences in the response of plasmacytoid dendritic cells (pDCs) to HIV-1. pDCs derived from women produce markedly more interferon-α (IFN-α) in response to HIV-1–encoded Toll-like receptor 7 (TLR7) ligands than pDCs derived from men, resulting in stronger secondary activation of CD8+ T cells. In line with these in vitro studies, treatment-naive women chronically infected with HIV-1 had considerably higher levels of CD8+ T cell activation than men after adjusting for viral load. These data show that sex differences in TLR-mediated activation of pDCs may account for higher immune activation in women compared to men at a given HIV-1 viral load and provide a mechanism by which the same level of viral replication might result in faster HIV-1 disease progression in women compared to men. Modulation of the TLR7 pathway in pDCs may therefore represent a new approach to reduce HIV-1–associated pathology.

Comparative Analysis of Measures of Viral Reservoirs in HIV-1 Eradication Studies

HIV-1 reservoirs preclude virus eradication in patients receiving highly active antiretroviral therapy (HAART). The best characterized reservoir is a small, difficult-to-quantify pool of resting memory CD4+ T cells carrying latent but replication-competent viral genomes. Because strategies targeting this latent reservoir are now being tested in clinical trials, well-validated high-throughput assays that quantify this reservoir are urgently needed. Here we compare eleven different approaches for quantitating persistent HIV-1 in 30 patients on HAART, using the original viral outgrowth assay for resting CD4+ T cells carrying inducible, replication-competent viral genomes as a standard for comparison. PCR-based assays for cells containing HIV-1 DNA gave infected cell frequencies at least 2 logs higher than the viral outgrowth assay, even in subjects who started HAART during acute/early infection. This difference may reflect defective viral genomes. The ratio of infected cell frequencies determined by viral outgrowth and PCR-based assays varied dramatically between patients. Although strong correlations with the viral outgrowth assay could not be formally excluded for most assays, correlations achieved statistical significance only for integrated HIV-1 DNA in peripheral blood mononuclear cells and HIV-1 RNA/DNA ratio in rectal CD4+ T cells. Residual viremia was below the limit of detection in many subjects and did not correlate with the viral outgrowth assays. The dramatic differences in infected cell frequencies and the lack of a precise correlation between culture and PCR-based assays raise the possibility that the successful clearance of latently infected cells may be masked by a larger and variable pool of cells with defective proviruses. These defective proviruses are detected by PCR but may not be affected by reactivation strategies and may not require eradication to accomplish an effective cure. A molecular understanding of the discrepancy between infected cell frequencies measured by viral outgrowth versus PCR assays is an urgent priority in HIV-1 cure research.

Risk of Anal Cancer in HIV-Infected and HIV-Uninfected Individuals in North America

BACKGROUND Anal cancer is one of the most common cancers affecting individuals infected with human immunodeficiency virus (HIV), although few have evaluated rates separately for men who have sex with men (MSM), other men, and women. There are also conflicting data regarding calendar trends. METHODS In a study involving 13 cohorts from North America with follow-up between 1996 and 2007, we compared anal cancer incidence rates among 34 189 HIV-infected (55% MSM, 19% other men, 26% women) and 114 260 HIV-uninfected individuals (90% men). RESULTS Among men, the unadjusted anal cancer incidence rates per 100 000 person-years were 131 for HIV-infected MSM, 46 for other HIV-infected men, and 2 for HIV-uninfected men, corresponding to demographically adjusted rate ratios (RRs) of 80.3 (95% confidence interval [CI], 42.7-151.1) for HIV-infected MSM and 26.7 (95% CI, 11.5-61.7) for other HIV-infected men compared with HIV-uninfected men. HIV-infected women had an anal cancer rate of 30/100 000 person-years, and no cases were observed for HIV-uninfected women. In a multivariable Poisson regression model, among HIV-infected individuals, the risk was higher for MSM compared with other men (RR, 3.3; 95% CI, 1.8-6.0), but no difference was observed comparing women with other men (RR, 1.0; 95% CI, 0.5-2.2). In comparison with the period 2000-2003, HIV-infected individuals had an adjusted RR of 0.5 (95% CI, .3-.9) in 1996-1999 and 0.9 (95% CI, .6-1.2) in 2004-2007. CONCLUSIONS Anal cancer rates were substantially higher for HIV-infected MSM, other men, and women compared with HIV-uninfected individuals, suggesting a need for universal prevention efforts. Rates increased after the early antiretroviral therapy era and then plateaued.

Coaxing HIV-1 from resting CD4 T cells: histone deacetylase inhibition allows latent viral expression.

Background: Histone deacetylase (HDAC), a host mediator of gene repression, inhibits HIV gene expression and virus production and may contribute to quiescence of HIV within resting CD4 T cells. Objectives: To test the ability of valproic acid (VPA), an inhibitor of HDAC in clinical use, to induce expression of HIV from resting CD4 T cells. Methods: Chromatin immunoprecipitation measured the capability of VPA to deacetylate the HIV promoter, a remodeling of chromatin linked to gene expression. The effect of VPA on resting CD4 T cell phenotype was measured by flow cytometric analysis, and its effect on de novo HIV infection of peripheral blood mononuclear cells was measured ex vivo. Outgrowth of HIV from resting CD4 T cells of aviremic, HIV-infected donors treated with highly active antiretroviral therapy was compared in limiting-dilution cultures after mitogen stimulation or exposure to VPA. Results: VPA induced acetylation at the integrated HIV proviral promoter, but CD4 cells exposed to VPA did not become activated or more permissive for de novo HIV infection. VPA induced outgrowth of HIV from the resting CD4 cells of aviremic patients at concentrations achievable in vivo as frequently as did mitogen stimulation. Conclusions: With advances in antiretroviral therapy, HIV infection might be cleared by intensive time-limited treatment coupled with practical strategies that disrupt latency without enhancing new infection. HDAC inhibitors are capable of inducing expression of quiescent provirus, without fully activating cells or enhancing de novo infection, and may be useful in future clinical protocols that seek to eradicate HIV infection.

The Effect of Raltegravir Intensification on Low-level Residual Viremia in HIV-Infected Patients on Antiretroviral Therapy: A Randomized Controlled Trial

In a double-blind trial, Rajesh Gandhi and colleagues detect no significant reduction in viral load after people with low-level HIV viremia added an integrase inhibitor to their treatment regimen.

Soluble Markers of Inflammation and Coagulation but Not T-Cell Activation Predict Non–AIDS-Defining Morbid Events During Suppressive Antiretroviral Treatment

BACKGROUND Defining the association of non-AIDS-defining events with inflammation and immune activation among human immunodeficiency virus (HIV)-infected persons with antiretroviral therapy (ART)-associated virological suppression is critical to identifying interventions to decrease the occurrence of these events. METHODS We conducted a case-control study of HIV-infected subjects who had achieved virological suppression within 1 year after ART initiation. Cases were patients who experienced non-AIDS-defining events, defined as myocardial infarction, stroke, non-AIDS-defining cancer, non-AIDS-defining serious bacterial infection, or death. Controls were matched to cases on the basis of age, sex, pre-ART CD4(+) T-cell count, and ART regimen. Peripheral blood mononuclear cells and plasma specimens obtained at the visit before ART initiation (hereafter, baseline), the visit approximately 1 year after ART initiation (hereafter, year 1), and the visit immediately preceding the non-AIDS-defining event (hereafter, pre-event) were analyzed for activated CD4(+) and CD8(+) T cells, plasma interleukin 6 (IL-6) level, soluble tumor necrosis factor receptor I (sTNFR-I) level, sTNFR-II level, soluble CD14 level, kynurenine-to-tryptophan (KT) ratio, and D-dimer level. Conditional logistic regression analysis was used to study the association between biomarkers and outcomes, with adjustment for potential confounders. RESULTS Higher IL-6 level, sTNFR-I level, sTNFR-II level, KT ratio, and D-dimer level at year 1 were associated with the occurrence of a non-AIDS-defining event. Significant associations were also seen between non-AIDS-defining events and values of these biomarkers in specimens obtained at baseline and the pre-event time points. Effects remained significant after control for confounders. T-cell activation was not significantly related to outcomes. CONCLUSIONS Interventional trials to decrease the incidence of non-AIDS-defining events among HIV-infected persons with virological suppression should consider targeting the pathways represented by these soluble markers. Clinical Trials Registration. NCT00001137.