HIV disease progression despite suppression of viral replication is associated with exhaustion of lymphopoiesis.

The mechanisms of CD4(+) T-cell count decline, the hallmark of HIV disease progression, and its relationship to elevated levels of immune activation are not fully understood. Massive depletion of CD4(+) T cells occurs during the course of HIV-1 infection, so that maintenance of adequate CD4(+) T-cell levels probably depends primarily on the capacity to renew depleted lymphocytes, that is, the lymphopoiesis. We performed here a comprehensive study of quantitative and qualitative attributes of CD34(+) hematopoietic progenitor cells directly from the blood of a large set of HIV-infected persons compared with uninfected donors, in particular the elderly. Our analyses underline a marked impairment of primary immune resources with the failure to maintain adequate lymphocyte counts. Systemic immune activation emerges as a major correlate of altered lymphopoiesis, which can be partially reversed with prolonged antiretroviral therapy. Importantly, HIV disease progression despite elite control of HIV replication or virologic success on antiretroviral treatment is associated with persistent damage to the lymphopoietic system or exhaustion of lymphopoiesis. These findings highlight the importance of primary hematopoietic resources in HIV pathogenesis and the response to antiretroviral treatments.

Raltegravir has no residual antiviral activity in vivo against HIV-1 with resistance-associated mutations to this drug.

OBJECTIVES: Emergence of major resistance mutations has already been associated with raltegravir regimen failure. Because of few remaining therapeutic options, the maintenance of raltegravir in the salvage regimen is often considered despite the risk of worsening resistance to integrase inhibitors. We determined whether raltegravir retains residual antiretroviral activity in vivo against viruses harbouring raltegravir mutations, and thus whether the drug can contribute to the subsequent regimen. METHODS: This retrospective observational study reports the changes in the viral load (VL) after the withdrawal of raltegravir from patients carrying virus with resistance mutations. We selected patients under stable treatment and with stable VL during at least the previous 2 months before the withdrawal. RESULTS: Five patients (A-E) were selected. The median changes in VL and CD4 counts at the end of the raltegravir interruption were -0.04 log copies/mL (range, -0.20 to +0.19) and +58 cells/mm(3) (range, -56 to +252), respectively. CONCLUSIONS: All VL changes were well below the clinically relevant variation of 0.5 log copies/mL at the end of the interruption. Thus, this study indicates that, for viruses harbouring one of the two main resistance pathways described for raltegravir, no relevant antiviral activity seems to persist in vivo. Even if further observations would be useful to reinforce this conclusion, the cost/benefit and risk/benefit of maintaining raltegravir as part of a salvage regimen in the presence of raltegravir mutations seem debatable, especially in the absence of relevant antiretroviral activity in this context.

No benefit of a structured treatment interruption based on genotypic resistance in heavily pretreated HIV-infected patients.

OBJECTIVE: To evaluate the potential benefits of a tailored antiretroviral treatment interruption with duration based on the observed reversion of resistance mutations. METHODS: In this open single-arm pilot study, 23 patients with multiple treatment failure interrupted therapy and underwent longitudinal genotypic resistance testing. Salvage gigatherapy was started when resistance mutations to at least two antiretroviral drug classes reverted. The primary endpoint was a fall in viral load by > 1 log10 copies/ml after 12 weeks of salvage therapy. RESULTS: Baseline median viral load was 5.14 log copies/ml and CD4 cell count 43 x 10 cells/l. Genotypic resistance testing showed a median of six, two and nine resistance mutations to nucleoside analogue reverse transcriptase inhibitors, non-nucleoside analogue reverse transcriptase inhibitors and protease inhibitors, respectively; viral strains were susceptible to no more than one drug in 17/23 patients. The median duration of treatment interruption was 24 weeks (range, 12-37), leading to median changes from baseline of + 0.54 log10 copies/ml and -30 x 10(6) cells/l. At the end of treatment interruption, plasma HIV was susceptible to at least three drugs in 16/23 patients. After 12 weeks of salvage multitherapy, only one patient had a decrease in viral load > 1 log copies/ml. All baseline resistance mutations recurred after treatment resumption. AIDS-defining events occurred in two-thirds of patients during the study period. CONCLUSION: In HIV-infected patients with multiple failures and no therapeutic options at baseline, significant reversion of resistance mutations after prolonged treatment interruption failed to restore antiviral efficacy of a salvage regimen and was clinically deleterious.

Modulation of interleukin-7 receptor expression characterizes differentiation of CD8 T cells specific for HIV, EBV and CMV.

OBJECTIVES: To further understand differentiation and homeostasis of CD8 T cells specific for HIV, Epstein-Barr Virus (EBV) and cytomegalovirus (CMV) during HIV infection, we investigated interleukin-7 receptor alpha (IL-7Ralpha) expression on those virus-specific T cells. METHODS: Microarrays and cytometry analyses were performed on peripheral blood mononuclear cells (PBMC), total and tetramer-binding virus-specific CD8 T cells from 66 HIV-infected patients. RESULTS: Microarray analysis revealed reduced levels of IL-7Ralpha and increased levels of perforin with disease progression in total PBMC. This loss of IL-7Ralpha expression was observed on CD8 T cells and was inversely related to perforin expression. The relative expression of both molecules defined three new subsets: IL-7Ralpha(pos)Perforin(neg); IL-7Ralpha(loneg)Perforin(lo); and IL-7Ralpha(loneg)Perforin(hi) corresponding to naive and effector-memory CD8 differentiation, as assessed by CD45RA/CD11a. The IL-7Ralpha expression decreased along the CD8 differentiation pathway defined by CD27 and CD28. In contrast, IL-7Ralpha expression was down-modulated on all the CD8 T cells specific for HIV, EBV and CMV that were almost exclusively IL-7Ralpha(lo/neg)Perforin(lo) and was parallel with the CD27 expression. In addition, this low IL-7Ralpha expression on HIV-specific CD8 T cells was independent of virus load and T-cell activation and remained stable during the first 6 months of antiretroviral therapy despite successful control of HIV replication. CONCLUSION: The relative expression of IL-7Ralpha, perforin reveals new aspects of virus-specific CD8 T cell differentiation, independently of T-cell activation and virus load. This opens new perspectives for understanding homeostasis of those cells and immune-based therapeutic strategies.

Efficacy of a twice-daily antiretroviral regimen containing 100 mg ritonavir/400 mg indinavir in HIV-infected patients.

OBJECTIVE: To evaluate the pharmacokinetics, efficacy and tolerability of a low-dose boosted indinavir (IDV)/ritonavir (RTV) regimen [100 mg RTV/400 mg IDV twice daily (bid)] in patients previously receiving a standard IDV regimen [800 mg three times a day (tid)]. METHODS: In a prospective, open-label, cross-over trial, patients with plasma HIV RNA < 200 copies/ml receiving an IDV-containing regimen (800 mg tid) were switched to an RTV/IDV (100/400 mg bid)-containing regimen. Minimal and maximal IDV plasma concentrations ( Cmin and Cmax ) were determined before the switch (day 0), at week 2 and week 4 after the switch. The CD4 cell count and plasma HIV RNA were determined at day 0, week 2 and week 4, then every 8 weeks. The primary end-point was the percentage of patients with plasma HIV RNA below 200 copies ml at week 48. RESULTS: Twenty patients were enrolled. At baseline, on IDV 800 mg tid, median IDV Cmin was 194 ng/ml and median IDV Cmax was 8449 ng/ml. On RTV/IDV (100/400 mg), median IDV Cmin increased to 536 ng/ml at week 2 and 475 ng/ml at week 4, while Cmax decreased to 2983 ng/ml at week 2 and 2997 ng/ml at week 4 ( P < 0.001). The median area under the IDV plasma concentration-time curve measured in seven patients was 25 126 ng.h/ml, and the IDV half-life (t1/2 ) was 4.4 h. All patients had plasma HIV RNA remaining < 200 copies/ml at week 48. Tolerability of RTV/IDV was excellent. CONCLUSION: RTV/IDV (100/400 mg bid) yields significantly higher IDV plasma Cmin and lower IDV Cmax values relative to the standard IDV regimen, thereby improving both tolerability and efficacy.

Efficacy and safety of ritonavir/indinavir 100/400 mg twice daily in combination with two nucleoside analogues in antiretroviral treatment-naive HIV-infected individuals.

OBJECTIVE: To evaluate the efficacy and tolerability of indinavir/ritonavir (IDV/RTV) 400/100 mg twice daily in combination with two nucleoside reverse transcriptase inhibitors in antiretroviral-naive patients. DESIGN AND METHODS: Antiviral therapy-naive patients with plasma HIV-1 RNA > 5000 copies/ml were enrolled in this pilot, single-arm study. CD4 cell count and viral load were evaluated at weeks (W) 4, 12, 24 and every 3 months until W48. The primary end-point was the percentage (%) of patients with viral load < 400 copies/ml at W48. Intent-to-treat (ITT) (missing values or change in treatment equalled failure) and on-treatment (OT) analyses were performed. RESULTS: Forty patients were enrolled. Baseline median viral load was 5.36 log10 copies/ml, median CD4 count was 84 cells/mm3. At W48 by ITT analysis, the % patients with viral load < 400 copies/ml was 65% (95% CI: 48-79) and 50% (95% CI: 35-65) with viral load < 50 copies/ml, and 96% (26/27) (95% CI: 89-100) and 74% (95% CI: 57-91], respectively, by OT analysis. The median decrease in viral load at W48 was -3.83 log10 copies/ml (-0.1; -5.19) and the median increase in CD4 was +167 cells/mm3 (6-474 cell/mm3). At W4 (34/40), the median IDV C(min) was 500 ng/ml (range 5-8100) with 91% of patients with an adequate IDV C(min) > 150 ng/ml. Ten patients discontinued the study treatment before W48: adverse events (eight), patient's will (one) and simplification of therapy (one). Three patients were lost to follow-up. Only one virological failure occurred and was associated with poor compliance and sub-optimal concentrations of IDV/RTV. CONCLUSIONS: IDV/RTV 400/100 mg twice daily is an effective and safe first-line antiretroviral therapy. The simplicity and the low cost of IDV/RTV is of major interest particularly in countries with limited resources.

Old age and anti-cytomegalovirus immunity are associated with altered T-cell reconstitution in HIV-1-infected patients.

OBJECTIVE AND DESIGN: Increasing evidence supports a parallel between HIV-1 infection and immune aging, which is particularly apparent with common changes in naive versus memory T-cell proportions. Here, we aimed at refining the value of common T-cell-associated markers of immunosenescence during HIV disease progression or aging, and at exploring further the impact in this context of old age as well as cytomegalovirus (CMV) co-infection, which is predominant in HIV-1-infected individuals. METHODS: Frequencies of naive or CD57(+) memory T cells as well as the magnitude of CMV-pp65 T cells were measured in HIV-1-infected patients grouped according to disease progression status, treatment and age. RESULTS: Our results indicate that the decline in naive T-cell levels rather than the accumulation of CD57(+) senescent T cells identifies best the premature development of an immunosenescence phenotype with HIV disease progression. Moreover, advanced age or mounting of strong CMV-specific responses impact independently on CD4(+) T-cell counts and recovery with antiretroviral therapy. CONCLUSIONS: The present findings indicate that HIV-1 infection amplifies the effect of age on naive T-cell levels, and highlight the constraint on the capacity of treated patients to reconstitute their CD4(+) T-cell compartment due to age and CMV co-infection.

Antiretroviral combinations implicated in emergence of the L74I and L74V resistance mutations in HIV-1-infected patients.

BACKGROUND: Very little is known about the alternative L74I mutation. This lack of knowledge has led to contradictory and confusing attitudes to L74I; although this mutation is not listed by the International AIDS Society - USA, it is increasingly included in several resistance algorithms. OBJECTIVE: To compare and clarify the role of each antiretroviral compound and the resistance background in the emergence of the L74I and L74V mutations. METHODS: We focused on the treatment used at the exact time of any L74V or L74I emergences in 74 patients, and we compared the use of each nucleoside reverse transcriptase inhibitor (NRTI) separately and in combination between the 74I and the 74V groups. The distribution of other NRTI and non-NRTI mutations between the two groups was also analysed. RESULTS: A majority of L74I mutations is selected under the zidovudine plus abacavir combination or under tenofovir with thymidine analogue mutations in the resistance background. The K103N substitution also plays an important role in the L74I emergence when not associated with the other non-NRTI mutations seen in this study: L100I, G190A and Y181C. Didanosine plays the principal role in the L74V emergence. CONCLUSIONS: This study shows that the L74I and the L74V correspond to two different mutation pathways, conferring probably different resistance and replication advantages on HIV depending on the context. Taking into account more systematically the L74I mutation, whose impact is certainly currently underestimated, would increase our understanding of this substitution and its effects on the drug activity in vivo.

Influence of antigen exposure on the loss of long-term memory to childhood vaccines in HIV-infected patients.

The role of antigen exposure and of CD4 cell deficiency in the long-term persistence of immune memory to childhood vaccines remains uncertain, particularly during HIV infection. We analyzed in vaccinated ART-treated HIV+ patients with undetectable plasma HIV and CD4 cells >250/mm(3) the persistence of two memory cell pools: effector IFNgamma-producing and proliferative central memory T cells against two vaccines: (i) vaccinia against the eradicated smallpox virus, and (ii) BCG against Mtb, a persistent pathogen. None of the HIV+ patients had IFNgamma-effector cells against VV while the one patient with BCG-specific effector T cells had a recent history of tuberculosis. Proliferative responses were detectable but showed significantly lower frequency and intensity of VV-specific than tuberculin-specific responses, independently of the CD4 nadir. Thus, differential patterns of persistence or recovery of T cell memory pools against childhood vaccines are observed in treated HIV infection that are governed by antigen exposure.

Comparison of the dynamics of resistance-associated mutations to nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors after cessation of antiretroviral combination therapy.

The dynamics of mutations associated with resistance to antiretroviral drugs were analyzed after cessation of therapy. The results showed that the kinetics of the shift to wild-type amino acid residues were significantly faster for protease inhibitors, intermediate for nonnucleoside reverse transcriptase inhibitors, and slower for nucleoside reverse transcriptase inhibitors.

Genotypic inhibitory quotient as predictor of virological response to ritonavir-amprenavir in human immunodeficiency virus type 1 protease inhibitor-experienced patients.

Forty-nine protease inhibitor (PI)-experienced but amprenavir (APV)-naïve patients experiencing virological failure were treated with ritonavir (RTV) (100 mg twice a day [b.i.d.]) plus APV (600 mg b.i.d.). Patients responded to therapy with a median viral load decrease of -1.32 log(10) by week 12. The addition of low-dose RTV enhanced the minimal APV concentration in plasma (APV C(min)) up to 10-fold compared with that obtained with APV (1,200 mg b.i.d.) without RTV. Baseline PI resistance mutations (L10F/I/V, K20M/R, E35D, R41K, I54V, L63P, V82A/F/T/S, I84V) identified by univariate analysis and included in a genotypic score and APV C(min) at week 8 were predictive of the virological response at week 12. The response to APV plus RTV was significantly reduced in patients with six or more of the resistance mutations among the ones defined above. The genotypic inhibitory quotient, calculated as the ratio of the APV C(min) to the number of human immunodeficiency virus type 1 protease mutations, was a better predictor than the virological or pharmacological variables used alone. This genotypic inhibitory quotient could be used in therapeutic drug monitoring to define the concentrations in plasma needed to control replication of viruses with different levels of PI resistance, as measured by the number of PI resistance mutations.