Immunological recovery and antiretroviral therapy in HIV-1 infection

Short-term and long-term risk of tuberculosis associated with CD4 cell recovery during antiretroviral therapy in South Africa

OBJECTIVE

To determine the short-term and long-term risks of tuberculosis (TB) associated with CD4 cell recovery during antiretroviral therapy (ART).

DESIGN

Observational community-based ART cohort in South Africa.

METHODS

TB incidence was determined among patients (n = 1480) receiving ART for up to 4.5 years in a South African community-based service. Updated CD4 cell counts were measured 4-monthly. Person-time accrued within a range of CD4 cell count strata (CD4 cell strata) was calculated and used to derive CD4 cell-stratified TB rates. Factors associated with incident TB were identified using Poisson regression models.

RESULTS

Two hundred and three cases of TB were diagnosed during 2785 person-years of observation (overall incidence, 7.3 cases/100 person-years). During person-time accrued within CD4 cell strata 0-100, 101-200, 201-300, 301-400, 401-500 and more than 500 cells/microl unadjusted TB incidence rates were 16.8, 9.3, 5.5, 4.6, 4.2 and 1.5 cases/100 person-years, respectively (P < 0.001). During early ART (first 4 months), adjusted TB rates among those with CD4 cell counts 0-200 cells/microl were 1.7-fold higher than during long-term ART (P = 0.026). Updated CD4 cell counts were the only patient characteristic independently associated with long-term TB risk.

CONCLUSION

Updated CD4 cell counts were the dominant predictor of TB risk during ART in this low-resource setting. Among those with baseline CD4 cell counts less than 200 cells/microl, the excess adjusted risk of TB during early ART was consistent with 'unmasking' of disease missed at baseline screening. TB incidence rates at CD4 cell counts of 200-500 cells/microl remained high and adjunctive interventions are required. TB prevention would be improved by ART policies that minimized the time patients spend with CD4 cell counts below a threshold of 500 cells/microl.

Eradication of Helicobacter pylori can facilitate immune reconstitution in HIV-1-infected immunological non-responders

OBJECTIVE

A significant number of HIV-1 patients experience poor immune reconstitution despite long-term viral suppression with highly active antiretroviral therapy (immunological non-responders). The aims of the present study were to determine whether eradication of Helicobacter pylori could facilitate a better immune reconstitution in these patients.

METHODS

Forty-nine immunological non-responder HIV-1 patients were evaluated by (13)C-urea breath test (UBT) for the presence of active H. pylori infection. They were all asymptomatic. The UBT was positive in 26 (53%) of them. Eleven patients (group 1) were treated with a combination of omeprazole 20mg bid, amoxicillin 1g bid and clarithromycin 500mg bid for 14 consecutive days. Eight weeks later, successful eradication was proven by a repeat negative UBT in all 11 patients. The remaining 15 (group 2) refused the H. pylori eradication treatment. All 26 patients were followed for 24 months and evaluated for blood CD4 and CD8 cell counts and percentages and for plasma HIV-1 viral load.

RESULTS

At the time of H. pylori diagnosis and eradication (baseline), CD4 and CD8 cell counts were similar in both study groups. All 11 H. pylori eradicated patients (group 1) had a significant increase in CD4 cell count starting 3 months and peaking 12-18 months after H. pylori eradication. Thereafter, CD4 levels gradually declined. Nevertheless, 24 months after triple therapy it was significantly higher than prior to H. pylori eradication. Parallel reciprocal changes were observed in CD8 cell counts. There were no significant changes in either CD4 or CD8 cell counts in group 2 patients. None of the patients of group 1 demonstrated virological failure, while four (26.7%) group 2 patients experienced virological failure requiring change of highly active antiretroviral therapy (HAART) regimen.

CONCLUSION

Triple therapy for H. pylori eradication is associated with a significant, although possibly transient immune reconstitution in HAART-treated HIV-1 patients with viral suppression without immunological response.

Immunotherapies in HIV-1 infection

PURPOSE OF REVIEW

The purpose of this review is to describe the current status of immunotherapies for the treatment of HIV-1 infection. This review is timely, as the results of the phase III clinical trials of recombinant interleukin-2 (rIL-2) as adjuncts to combination antiretroviral therapy are about to be released.

RECENT FINDINGS

For many years, the use of rIL-2 in HIV-infected individuals has been explored. Although the results of the clinical endpoint studies of rIL-2 are awaited, there are now further data for rIL-2 as a stand-alone therapy for the treatment of HIV. Maraviroc, a recently approved anti-HIV agent, is a small molecule antagonist of human chemokine receptor-5. The recent observation that maraviroc-treated patients achieved higher CD4 and CD8 T-cell counts compared with comparator regimens (without a chemokine receptor-5 antagonist) for equivalent viral load reductions has fueled interest in using these host-directed therapies to enhance immune restoration.

SUMMARY

This review summarizes the most recent clinical data for rIL-2 and reviews other immunotherapies in earlier development including cytokines rIL-7, rIL-15, rIL-21, new therapeutic vaccination approaches including infusion of overlapping HIV peptides and dendritic cell immunotherapy and novel agents including luteinizing hormone-releasing hormone analogues and vitamin D3-binding protein macrophage activating factor.

The effect of AIDS defining conditions on immunological recovery among patients initiating antiretroviral therapy at Joint Clinical Research Centre, Uganda

Background

Many HIV-infected patients only access health care once they have developed advanced symptomatic disease resulting from AIDS Defining Conditions (ADCs). We carried out a study to establish the effect of ADCs on immunological recovery among patients initiated on antiretroviral therapy (ART).

Methods

A retrospective cohort of 427 HIV-1 patients who were initiated on ART between January 2002 and December 2006 was studied. Data on ADCs was retrieved from Joint Clinical Research Centre (JCRC) data base and backed up by chart reviews. We employed Kaplan-Meier survival curves to estimate median time to 50 CD4 cells/μl from the baseline value to indicate a good immunological recovery process. Cox proportional hazard models were used at multivariate analysis.

Results

The median time to gaining 50 CD4 cells/μl from the baseline value after ART initiation was longer in the ADC (9.3 months) compared to the non-ADC group (6.9 months) (log rank test, p = 0.027). At multivariate analysis after adjusting for age, sex, baseline CD4 count, baseline HIV viral load, total lymphocyte count and adherence level, factors that shortened the median time to immunological recovery after ART initiation were belonging to the non-ADC group (HR = 1.31; 95% CI: 1.03–1.28, p = 0.028), adherence to ART of ≥ 95% (HR = 2.22; 95% CI: 1.57–3.15, p = 0.001) and a total lymphocyte count ≥ 1200 cells/mm³ (HR = 1.84; 95% CI: 1.22–2.78, p = 0.003). A low baseline CD4 count of ≤ 200 cells/μl (HR = 0.52; 95% CI: 0.37–0.77, p = 0.001) was associated with a longer time to immunological recovery. There was no interaction between low CD4 counts and ADC group.

Conclusion

Patients with ADCs take longer to regain their CD4 counts due to the defect in the immune system. This may prolong their risk of morbidity and mortality.

Dissection of regenerating T-Cell responses against tuberculosis in HIV-infected adults sensitized by Mycobacterium tuberculosis

RATIONALE

Combination antiretroviral treatment (cART) reduces the risk of tuberculosis in HIV-infected people. Therefore a novel approach to gain insight into protection against tuberculosis is to analyze the T cells that expand in people sensitized by Mycobacterium tuberculosis (MTB) during cART.

OBJECTIVES

To longitudinally analyze CD4 T-cell subsets during the first year of cART, from the time of starting cART (Day 0), in 19 HIV-infected, MTB-sensitized adults.

METHODS

Peripheral blood mononuclear cells were obtained on Day 0, Weeks 2, 4, 12, 24, 36, and 48 of cART and were stimulated with purified protein derivative (PPD) followed by flow cytometry to analyze surface markers and intracellular cytokines.

MEASUREMENTS AND MAIN RESULTS

CD4(+) T cells significantly increased during follow-up and the viral load fell to undetectable levels in each patient, indicating successful immune restoration. Central memory CD27(+)CD45RA(-) and CD27(+)CCR5(-) CD4(+) cells expanded by 12 weeks (P < 0.02) followed by naive CD27(+)CD45RA(+) cells at 36 weeks (P = 0.02). Terminally differentiated effector CD4(+)CD27(-)CCR7(-) cells decreased by 12 weeks (P = 0.02), paralleled by a proportional decline of PPD-specific CD4(+)IFN-gamma(+) cells (P = 0.02). However, the absolute numbers of PPD-specific IFN-gamma-producing cells, determined by enzyme-linked immunospot assay, increased (P = 0.02).

CONCLUSIONS

Rapid effector responses are often measured when evaluating immunity. We show that although cART is associated with an absolute increase in effector function, the proportional response decreased and the strongest correlate of increased cART-mediated immunity in this study was the central memory response.

[53 year-old patient with fever and cough]

We describe a patient with late HIV presentation, opportunistic infections and an immune reconstitution syndrome (IRIS) after starting a combination antiretroviral therapy (ART)occurring in this severely immunodeficient patient. In the beginning, a miliary tuberculosis was diagnoses, followed by a second opportunistic infection, i.e. pneumocystis jiroveci pneumonia. After start of ART, further organ manifestations developed, interpreted as immune reconstitution syndrome. The decision about the optimal time point for starting ART in the presence of an opportunistic infection is essential.

Immune reconstitution inflammatory syndrome among HIV-infected South African infants initiating antiretroviral therapy

OBJECTIVES

To determine the incidence, clinical manifestations and risk factors for immune reconstitution inflammatory syndrome (IRIS) in young children initiating highly active antiretroviral therapy (HAART).

DESIGN

A prospective cohort of antiretroviral-naïve HIV-infected children less than 24 months of age enrolled in a treatment strategies trial in Johannesburg, South Africa.

METHODS

Among 169 HIV-infected children initiating HAART, April 2005 to November 2006, the records of 83 children suspected to have IRIS within 6 months of starting treatment were reviewed to determine whether they met criteria for IRIS. Seven were excluded due to incomplete follow-up. Pretreatment and post-treatment characteristics of children with and without IRIS were compared.

RESULTS

Overall, 34/162 (21%) children developed IRIS at a median of 16 days (range 7-115 days) post-HAART initiation. Bacille Calmette-Guérin reaction was most common occurring in 24/34 (71%) children, primarily injection site lesions and/or ipsilateral axillary lymphadenitis with abscess. Other IRIS conditions (not mutually exclusive) included Mycobacterium tuberculosis (n = 12), cytomegalovirus pneumonia (n = 1), Streptococcus pneumonia sepsis (n = 1), and severe seborrheic dermatitis (n = 1). Children with IRIS were younger (median age 7 vs. 10 months, P = 0.007) with a lower CD4 cell percentage (median 13.9 vs. 19.2, P = 0.009) at HAART initiation than controls. After 24 weeks on HAART, 62% of IRIS cases vs. 28% of controls had HIV RNA more than 400 copies/ml (P = 0.001), odds ratio = 2.88 (95% confidence interval = 1.14-7.29) after adjusting for baseline factors.

CONCLUSION

Infants and young children with advanced HIV disease initiating HAART are at high risk for developing IRIS, leading to additional morbidity and possibly impairing virologic response to antiretroviral treatment.

Evolution of CD4+ T cell count in HIV-1-infected adults receiving antiretroviral therapy with sustained long-term virological suppression

It is not fully elucidated whether patients who receive antiretroviral therapy (ART) can maintain continued CD4 count increases. Previous studies suggested a plateau 2-4 years after treatment initiation. We aimed to characterize the evolution of CD4 counts in HIV-infected individuals receiving long-term suppressive ART, by performing a retrospective study of patients who maintained viral suppression (HIV RNA <400 copies/ml) for > or =5 years. We used linear regression models to determine for each individual whether the CD4 count continued to increase or plateau. Furthermore, we estimated whether the slope of the CD4 count for each individual became zero, which we defined as the CD4 set-point. We assessed factors associated with continued CD4 count rise, reaching a CD4 set-point and time to the CD4 set-point. Fifty-nine patients were included. The median baseline CD4 count was 238 (IQR, 120-360) cells/microl and the median duration on ART was 7.6 (IQR, 5.9-9.3) years. On ART, CD4 count continued to increase in 37 subjects (63%). Significant predictors of continued CD4 count increase included a lower baseline log10 HIV RNA (OR, 0.35; 95% CI, 0.14-0.89; p=0.026) and a shorter duration on ART (OR, 0.65; 95% CI, 0.47-0.91; p=0.021). Twenty-four (41%) subjects reached a set-point after a median 4.3 (IQR 1.8-6.4) years on ART. A lower baseline CD4 percentage was associated with both a longer time to reach the CD4 set-point and a lower CD4 count at the CD4 set-point. These findings suggest that CD4 count may continue to increase in some patients after several years of ART. Our results point to an advantage to commencing ART at higher CD4+ T cell strata. These data should be considered when estimating the optimal time to initiate ART.

HIV-1 superinfection in the antiretroviral therapy era: are seroconcordant sexual partners at risk?

Background

Acquisition of more than one strain of human immunodeficiency virus type 1 (HIV-1) has been reported to occur both during and after primary infection, but the risks and repercussions of dual and superinfection are incompletely understood. In this study, we evaluated a longitudinal cohort of chronically HIV-infected men who were sexual partners to determine if individuals acquired their partners' viral strains.

Methodology

Our cohort of HIV-positive men consisted of 8 couples that identified themselves as long-term sexual partners. Viral sequences were isolated from each subject and analyzed using phylogenetic methods. In addition, strain-specific PCR allowed us to search for partners' viruses present at low levels. Finally, we used computational algorithms to evaluate for recombination between partners' viral strains.

Principal Findings/Conclusions

All couples had at least one factor associated with increased risk for acquisition of new HIV strains during the study, including detectable plasma viral load, sexually transmitted infections, and unprotected sex. One subject was dually HIV-1 infected, but neither strain corresponded to that of his partner. Three couples' sequences formed monophyletic clusters at the entry visit, with phylogenetic analysis suggesting that one member of the couple had acquired an HIV strain from his identified partner or that both had acquired it from the same source outside their partnership. The 5 remaining couples initially displayed no evidence of dual infection, using phylogenetic analysis and strain-specific PCR. However, in 1 of these couples, further analysis revealed recombinant viral strains with segments of viral genomes in one subject that may have derived from the enrolled partner. Thus, chronically HIV-1 infected individuals may become superinfected with additional HIV strains from their seroconcordant sexual partners. In some cases, HIV-1 superinfection may become apparent when recombinant viral strains are detected.

Benefit of antiretroviral therapy on survival of human immunodeficiency virus-infected patients admitted to an intensive care unit

OBJECTIVE

To evaluate the impact of antiretroviral therapy (ART) and the prognostic factors for in-intensive care unit (ICU) and 6-month mortality in human immunodeficiency virus (HIV)-infected patients.

DESIGN

A retrospective cohort study was conducted in patients admitted to the ICU from 1996 through 2006. The follow-up period extended for 6 months after ICU admission.

SETTING

The ICU of a tertiary-care teaching hospital at the Universidade de São Paulo, Brazil.

PARTICIPANTS

A total of 278 HIV-infected patients admitted to the ICU were selected. We excluded ICU readmissions (37), ICU admissions who stayed less than 24 hours (44), and patients with unavailable medical charts (36).

OUTCOME MEASURE

In-ICU and 6-month mortality.

MAIN RESULTS

Multivariate logistic regression analysis and Cox proportional hazards models demonstrated that the variables associated with in-ICU and 6-month mortality were sepsis as the cause of admission (odds ratio [OR] = 3.16 [95% confidence interval [CI] 1.65-6.06]); hazards ratio [HR] = 1.37 [95% CI 1.01-1.88]), an Acute Physiology and Chronic Health Evaluation II score >19 [OR = 2.81 (95% CI 1.57-5.04); HR = 2.18 (95% CI 1.62-2.94)], mechanical ventilation during the first 24 hours [OR = 3.92 (95% CI 2.20-6.96); HR = 2.25 (95% CI 1.65-3.07)], and year of ICU admission [OR = 0.90 (95% CI 0.81-0.99); HR = 0.92 [95% CI 0.87-0.97)]. CD4 T-cell count <50 cells/mm(3) was only associated with ICU mortality [OR = 2.10 (95% CI 1.17-3.76)]. The use of ART in the ICU was negatively predictive of 6-month mortality in the Cox model [HR = 0.50 (95% CI 0.35-0.71)], especially if this therapy was introduced during the first 4 days of admission to the ICU [HR = 0.58 (95% CI 0.41-0.83)]. Regarding HIV-infected patients admitted to ICU without using ART, those who have started this treatment during ICU stay presented a better prognosis when time and potential confounding factors were adjusted for [HR 0.55 (95% CI 0.31-0.98)].

CONCLUSIONS

The ICU outcome of HIV-infected patients seems to be dependent not only on acute illness severity, but also on the administration of antiretroviral treatment.

Specific immunotherapy in a pollen-allergic patient with human immunodeficiency virus infection

BACKGROUND

: According to the World Health Organization position paper, immunodeficiency such as human immunodeficiency virus (HIV) infection is a relative contraindication for specific immunotherapy (SIT). Since the introduction of highly active antiretroviral therapy, a significant reconstitution of immune competence in individuals with HIV is possible.

CASE REPORT

: In a 52-year-old man, HIV infection was diagnosed in 1987. Antiretroviral therapy was started in 1998. He presented himself in July 2001 because of an increasingly severe seasonal rhinoconjunctivitis. Symptoms were not sufficiently alleviated by various antiallergic drugs.

RESULTS

: The investigations showed a relevant sensitization to tree pollens. Specific immunotherapy with a tree pollen mix (hazel, birch, ash, and alder, 25% each) was started in November 2001. Viral load at this time was less than 50 copies/mL, the CD4 cell count was 307/μL. Therapy was given in monthly intervals until mid-April 2005 without any side effects. Viral load and CD4 cell counts did not change during SIT. Clinically, rhinoconjunctivitis was experienced only intermittently and symptom relief was almost 90%.

CONCLUSIONS

: This report indicates that in patients with well-controlled HIV infection on highly active antiretroviral therapy, SIT with pollen extracts is a potential and successful therapeutic option.

Incomplete peripheral CD4+ cell count restoration in HIV-infected patients receiving long-term antiretroviral treatment

BACKGROUND

Although antiretroviral therapy has the ability to fully restore a normal CD4(+) cell count (>500 cells/mm(3)) in most patients, it is not yet clear whether all patients can achieve normalization of their CD4(+) cell count, in part because no study has followed up patients for >7 years.

METHODS

Three hundred sixty-six patients from 5 clinical cohorts who maintained a plasma human immunodeficiency virus (HIV) RNA level 1000 copies/mL for at least 4 years after initiation of antiretroviral therapy were included. Changes in CD4(+) cell count were evaluated using mixed-effects modeling, spline-smoothing regression, and Kaplan-Meier techniques.

RESULTS

The majority (83%) of the patients were men. The median CD4(+) cell count at the time of therapy initiation was 201 cells/mm(3) (interquartile range, 72-344 cells/mm(3)), and the median age was 47 years. The median follow-up period was 7.5 years (interquartile range, 5.5-9.7 years). CD4(+) cell counts continued to increase throughout the follow-up period, albeit slowly after year 4. Although almost all patients (95%) who started therapy with a CD4(+) cell count 300 cells/mm(3) were able to attain a CD4(+) cell count 500 cells/mm(3), 44% of patients who started therapy with a CD4(+) cell count <100 cells/mm(3) and 25% of patients who started therapy with a CD4(+) cell count of 100-200 cells/mm(3) were unable to achieve a CD4(+) cell count >500 cells/mm(3) over a mean duration of follow-up of 7.5 years; many did not reach this threshold by year 10. Twenty-four percent of individuals with a CD4(+) cell count <500 cells/mm(3) at year 4 had evidence of a CD4(+) cell count plateau after year 4. The frequency of detectable viremia ("blips") after year 4 was not associated with the magnitude of the CD4(+) cell count change.

CONCLUSIONS

A substantial proportion of patients who delay therapy until their CD4(+) cell count decreases to <200 cells/mm(3) do not achieve a normal CD4(+) cell count, even after a decade of otherwise effective antiretroviral therapy. Although the majority of patients have evidence of slow increases in their CD4(+) cell count over time, many do not. These individuals may have an elevated risk of non-AIDS-related morbidity and mortality.

Changing mortality risk associated with CD4 cell response to antiretroviral therapy in South Africa

OBJECTIVE

To determine the relationship between mortality risk and the CD4 cell response to antiretroviral therapy (ART).

DESIGN

Observational community-based ART cohort in South Africa.

METHODS

CD4 cell counts were measured 4 monthly, and deaths were prospectively ascertained. Cumulative person-time accrued within a range of updated CD4 cell count strata (CD4 cell-strata) was calculated and used to derive CD4 cell-stratified mortality rates.

RESULTS

Patients (2423) (median baseline CD4 cell count of 105 cells/microl) were observed for up to 5 years of ART. One hundred and ninety-seven patients died during 3155 person-years of observation. In microltivariate analysis, mortality rate ratios associated with 0-49, 50-99, 100-199, 200-299, 300-399, 400-499 and at least 500 cells/microl updated CD4 cell-strata were 11.6, 4.9, 2.6, 1.7, 1.5, 1.4 and 1.0, respectively. Analysis of CD4 cell count recovery permitted calculations of person-time accrued within these CD4 cell-strata. Despite rapid immune recovery, high mortality in the first year of ART was related to the large proportion of person-time accrued within CD4 cell-strata less than 200 cells/microl. Moreover, patients with baseline CD4 cell counts less than 100 cells/microl had much higher cumulative mortality estimates at 1 and 4 years (11.6 and 16.7%) compared with those of patients with baseline counts of at least 100 cells/microl (5.2 and 9.5%) largely because of greater cumulative person-time at CD4 cell counts less than 200 cells/microl.

CONCLUSION

Updated CD4 cell counts are the variable most strongly associated with mortality risk during ART. High cumicrolative mortality risk is associated with person-time accrued at low CD4 cell counts. National HIV programmes in resource-limited settings should be designed to minimize the time patients spend with CD4 cell counts less than 200 cells/microl both before and during ART.

Dendritic cell-based human immunodeficiency virus vaccine

Dendritic cells (DC) have profound abilities to induce and coordinate T-cell immunity. This makes them ideal biological agents for use in immunotherapeutic strategies to augment T-cell immunity to HIV infection. Current clinical trials are administering DC-HIV antigen preparations carried out ex vivo as proof of principle that DC immunotherapy is safe and efficacious in HIV-infected patients. These trials are largely dependent on preclinical studies that will provide knowledge and guidance about the types of DC, form of HIV antigen, method of DC maturation, route of DC administration, measures of anti-HIV immune function and ultimately control of HIV replication. Additionally, promising immunotherapy approaches are being developed based on targeting of DC with HIV antigens in vivo. The objective is to define a safe and effective strategy for enhancing control of HIV infection in patients undergoing antiretroviral therapy.

Immunological profiles of immune restoration disease presenting as mycobacterial lymphadenitis and cryptococcal meningitis

OBJECTIVES

A proportion of HIV patients beginning antiretroviral therapy (ART) develop immune restoration disease (IRD). Immunological characteristics of IRD were investigated in a cohort of HIV patients beginning therapy in Kuala Lumpur, Malaysia.

METHODS

Peripheral blood mononuclear cells were collected at weeks 0, 6, 12, 24 and 48 of ART from five patients experiencing IRD [two with cryptococcal and three with Mycobacterium tuberculosis (Mtb) disease], eight non-IRD controls who had begun ART with CD4 T-cell counts of <100 cells/microL and 17 healthy controls. Leukocytes producing interferon-gamma (IFNgamma) were quantified by enzyme-linked immunospot assay after stimulation with purified protein derivative (PPD), early secretory antigenic target-6 (ESAT-6), Cryptococcus neoformans or Cytomegalovirus antigens. Plasma immunoglobulin (IgG) antibodies reactive with these antigens were assessed by enzyme-linked immunosorbent assay. Proportions of activated (HLA-DR(hi)) and regulatory (CD25 CD127(lo) and CTLA-4(+)) CD4 T-cells were quantified by flow cytometry.

RESULTS

Plasma HIV RNA declined and CD4 T-cell counts rose within 8-27 weeks on ART. Mtb IRD patients displayed elevated IFNgamma responses and/or plasma IgG to PPD, but none responded to ESAT-6. Cryptococcal IRD occurred in patients with low baseline CD4 T-cell counts and involved clear IFNgamma and antibody responses to cryptococcal antigen. Proportions of activated and regulatory CD4 T-cells declined on ART, but remained higher in patients than in healthy controls. At the time of IRD, proportions of activated CD4 T-cells and regulatory CD4 T-cells were generally elevated relative to other patients.

CONCLUSIONS

Cryptococcal and Mtb IRD generally coincide with peaks in the proportion of activated T-cells, pathogen-specific IFNgamma responses and reactive plasma IgG. IRD does not reflect a paucity of regulatory CD4 T-cells.

Vitamin D deficiency among HIV type 1-infected individuals in the Netherlands: effects of antiretroviral therapy

Vitamin D regulates bone metabolism but has also immunoregulatory properties. In HIV-infected patients bone disorders are increasingly observed. Furthermore, low 1,25(OH)(2)D(3) levels have been associated with low CD4(+) counts, immunological hyperactivity, and AIDS progression rates. Few studies have examined the vitamin D status in HIV-infected patients. This study will specifically focus on the effects of antiretroviral agents on vitamin D status. Furthermore, the effect of vitamin D status on CD4 cell recovery after initiation of HAART will be evaluated. Among 252 included patients the prevalence of vitamin D deficiency (<35 nmol/liter from April to September and <25 nmol/liter from October to March) was 29%. Female sex, younger age, dark skin, and NNRTI treatment were significant risk factors in univariate analysis, although in multivariate analyses skin pigmentation remained the only independent risk factor. Median 25(OH)D(3) levels were significantly lower in white NNRTI-treated patients [54.5(27.9-73.8) nmol/liter] compared to white PI-treated patients [77.3 (46.6-100.0) nmol/liter, p = 0.007], while among nonwhites no difference was observed. Both PI- and NNRTI-treated patients had significantly higher blood PTH levels than patients without treatment. Moreover, NNRTI treatment puts patients at risk of elevated PTH levels (>6.5 pmol/liter). Linear regression analysis showed that vitamin D status did not affect CD4 cell recovery after initiation of HAART. In conclusion, 29% of the HIV-1-infected patients had vitamin D deficiency, with skin color as an independent risk factor. NNRTI treatment may add more risk for vitamin D deficiency. Both PI- and NNRTI-treated patients showed higher PTH levels and might therefore be at risk of bone problems. Evaluation of 25(OH)D(3) and PTH levels, especially in NNRTI-treated and dark skinned HIV-1-infected patients, is necessary to detect and treat vitamin D deficiency early.

Immune reconstitution inflammatory syndrome and human immunodeficiency virus-associated myocarditis

Myocarditis is a well-recognized cardiac manifestation of human immunodeficiency virus (HIV) infection, and alterations in the immune system likely play an important role in the pathogenesis of heart muscle disease in HIV-infected patients. Highly active antiretroviral therapy (HAART) has greatly improved survival in HIV patients but not without uncovering new and unique manifestations of disease. Immune reconstitution inflammatory syndrome is a collection of inflammatory disorders in which a pathologic inflammatory response and clinical deterioration occur during recovery of the immune system after HAART. To our knowledge, a correlation between immune reconstitution inflammatory syndrome and HIV-associated myocarditis has not been described previously. We report a case of acute myocarditis presenting with refractory ventricular arrhythmias in a patient with AIDS who experienced rapid immune recovery with the initiation of HAART. The case underscores the importance of recognizing this potential complication of AIDS treatment and calls for renewed vigilance concerning cardiac manifestations of HIV, especially during the immune reconstitution phase.

Cost-effectiveness of HIV monitoring strategies in resource-limited settings: a southern African analysis

BACKGROUND

Although the number of infected persons receiving highly active antiretroviral therapy (HAART) in low- and middle-income countries has increased dramatically, optimal disease management is not well defined.

METHODS

We developed a model to compare the costs and benefits of 3 types of human immunodeficiency virus monitoring strategies: symptom-based strategies, CD4-based strategies, and CD4 counts plus viral load strategies for starting, switching, and stopping HAART. We used clinical and cost data from southern Africa and performed a cost-effectiveness analysis. All assumptions were tested in sensitivity analyses.

RESULTS

Compared with the symptom-based approaches, monitoring CD4 counts every 6 months and starting treatment at a threshold of 200/muL was associated with a gain in life expectancy of 6.5 months (61.9 months vs 68.4 months) and a discounted lifetime cost savings of US $464 per person (US $4069 vs US $3605, discounted 2007 dollars). The CD4-based strategies in which treatment was started at the higher threshold of 350/microL provided an additional gain in life expectancy of 5.3 months at a cost-effectiveness of US $107 per life-year gained compared with a threshold of 200/microL. Monitoring viral load with CD4 was more expensive than monitoring CD4 counts alone, added 2.0 months of life, and had an incremental cost-effectiveness ratio of US $5414 per life-year gained relative to monitoring of CD4 counts. In sensitivity analyses, the cost savings from CD4 count monitoring compared with the symptom-based approaches was sensitive to cost of inpatient care, and the cost-effectiveness of viral load monitoring was influenced by the per test costs and rates of virologic failure.

CONCLUSIONS

Use of CD4 monitoring and early initiation of HAART in southern Africa provides large health benefits relative to symptom-based approaches for HAART management. In southern African countries with relatively high costs of hospitalization, CD4 monitoring would likely reduce total health care expenditures. The cost-effectiveness of viral load monitoring depends on test prices and rates of virologic failure.

CD4 cell response before and after HAART initiation according to viral load and growth indicators in HIV-1-infected children in Abidjan, Côte d'Ivoire

OBJECTIVE

To analyze the determinants of CD4 change in children during 3 periods: before highly active antiretroviral therapy (HAART), during the first year after HAART initiation, and past 1 year after HAART initiation.

METHODS

One hundred seventy-seven children enrolled in a prospective cohort in Abidjan received HAART during a mean follow-up of 30 months. A linear mixed-effects model was used for the first period, a mixed-effects piecewise model for the second period, and an asymptotic mixed-effects model for long-term CD4 dynamics.

RESULTS

Before HAART initiation, CD4 percentage decreased along time [beta = -0.59 (-0.92 to -0.26)] was positively associated with body mass index for age [beta = 0.47 (0.22 to 0.72)] and negatively associated with viral load [beta = -1.01 (-1.90 to -0.13)]. During the first year of treatment, the CD4 decrease reverted to a steep increase that was negatively associated with age at HAART initiation [beta = -0.24 (-0.4 to -0.07)] and with the mean viral load under HAART [beta = -1.51 (-2.21 to -0.81)]. The long-term CD4 percentage was also negatively associated with the mean viral load under HAART [beta = -4.97 (-6.22 to -3.72)] and age at HAART initiation [beta = -0.82 (-1.12 to -0.51)].

CONCLUSIONS

Before HAART initiation, the CD4 cell percentage was associated with growth indicators whereas, after HAART, an early increase and a long-term plateau were negatively associated with the viral load and age at HAART initiation.

Selective killing of HIV-1-positive macrophages and T cells by the Rev-dependent lentivirus carrying anthrolysin O from Bacillus anthracis

Background

The ability of Human Immunodeficiency Virus (HIV) to persist in the body has proven to be a long-standing challenge to virus eradication. Current antiretroviral therapy cannot selectively destroy infected cells; it only halts active viral replication. With therapeutic cessation or interruption, viral rebound occurs, and invariably, viral loads return to pre-treatment levels. The natural reservoirs harboring replication-competent HIV-1 include CD4 T cells and macrophages. In particular, cells from the macrophage lineage resist HIV-1-mediated killing and support sustained viral production. To develop a complementary strategy to target persistently infected cells, this proof-of-concept study explores an HIV-1 Rev-dependent lentiviral vector carrying a bacterial hemolysin, anthrolysin O (anlO) from Bacillus anthracis, to achieve selective killing of HIV-1- infected cells.

Results

We demonstrate that in the Rev-dependent lentiviral vector, anlO expression is exclusively dependent on Rev, a unique HIV-1 protein present only in infected cells. Intracellular expression and oligomerization of AnlO result in membrane pore formation and cytolysis. We have further overcome a technical hurdle in producing a Revdependent AnlO lentivirus, through the use of β-cyclodextrin derivatives to inhibit direct killing of producer cells by AnlO. Using HIV-1-infected macrophages and T cells as a model, we demonstrate that this Rev-dependent AnlO lentivirus diminishes HIV-1- positive cells.

Conclusion

The Rev-dependent lentiviral vector has demonstrated its specificity in targeting persistently infected cells. The choice of anlO as the first suicidal gene tested in this vector is based on its cytolytic activity in macrophages and T cells. We conclude that Rev-regulated expression of suicidal genes in HIV-1-positive cells is possible, although future in vivo delivery of this system needs to address numerous safety issues.

Effect of antiretroviral therapy on apoptosis markers and morphology in peripheral lymph nodes of HIV-infected individuals

BACKGROUND

CD4+ T cell depletion and destruction and the involution of the lymphoid tissue are hallmarks of HIV infection. Although the underlying mechanisms are still unclear, apoptosis appears to play a central role. The objective of this study was to investigate the effect of antiretroviral therapy on the lymph node tissue, particularly with respect to morphology and apoptosis.

PATIENTS AND METHODS

Between 1997 and 1999, two inguinal lymph nodes were excised from 31 previously untreated individuals who were in an early stage of HIV infection, the first one prior to treatment and the second after 16 to 20 months of treatment. Paraffin sections were investigated for lymph node architecture, distribution of cellular and viral markers, apoptosis, and expression of apoptotic key molecules which indirectly reflect apoptotic processes.

RESULTS

After 16-20 months of antiretroviral therapy, a significant decrease in highly activated HIV-driven immune response was observed in the lymph node tissue as a marked reduction in follicular hyperplasia, a normalization of the follicular dendritic cell network, a significant increase in the number of CD4+ T cells, and a significant decrease in the number of CD8+ T cells. The expression of several proapoptotic (Fas, TRAIL, and active caspase 3) and antiapoptotic (Bcl-2 and IL-7Ralpha) molecules that were reconstituted in the tissues during therapy resembled their expression in lymph nodes of HIV-negative individuals. Limitations of the study are (a) the lack of untreated patients in the late stages, (b) for ethical reasons, the lack of a control group with untreated patients, and (c) for methodological reasons, the restriction of sequential measurements of apotpotic markers to one-third of the patients.

CONCLUSION

Antiretroviral therapy initiated in the early stages in HIV infection may halt the irreversible destruction of the lymph node tissue and may partially normalize apoptotic processes.

Immune reconstitution and "unmasking" of tuberculosis during antiretroviral therapy

Tuberculosis (TB) is the most common opportunistic disease in HIV-infected patients during the initial months of antiretroviral therapy (ART) and presents a great challenge to ART programs in resource-limited settings. The mechanisms underlying development of TB in this period are complex. Some cases may represent progression of undiagnosed subclinical disease present before starting ART, emphasizing the importance of careful screening strategies for TB. It has been suggested that progression in such cases is due to immune reconstitution disease-a phenomenon in which dysregulated restoration of pathogen-specific immune responses triggers the presentation of subclinical disease. However, whereas some cases have exaggerated or overtly inflammatory manifestations consistent with existing case definitions for IRD, many others do not. Moreover, since ART-induced immune recovery is a time-dependent process, active TB may develop as a consequence of persisting immunodeficiency. All these mechanisms are likely to be important, representing a spectrum of complex interactions between mycobacterial burden and changing host immune response. We propose that the potential range of effects of ART includes (1) shortening of the time for subclinical TB to become symptomatic (a phenomenon often referred to as "unmasking"), (2) increased rapidity of initial onset of TB symptoms, and (3) heightened intensity of clinical manifestations. We suggest that the term "ART-associated TB" be used to refer collectively to all cases of TB presenting during ART and that "immune reconstitution disease" be used to refer to the subset of ART-associated TB cases in which the effect on disease severity results in exaggerated and overtly inflammatory disease.

CD4+ T lymphocytes enumeration by an easy-to-use single platform image cytometer for HIV monitoring in resource-constrained settings

BACKGROUND

HIV monitoring in resource-constrained settings demands affordable and reliable CD4(+) T lymphocytes enumeration methods. We developed a simple single platform image cytometer (SP ICM), which is a dedicated volumetric CD4(+) T lymphocytes enumeration system that uses immunomagnetic and immunofluorescent technologies. The instrument was designed to be a low-cost, yet reliable and robust one. In this article we test the instrument and the immunochemical procedures used on blood from HIV negative and HIV positive patients.

METHODS

After CD4 immunomagnetic labeling in whole blood, CD4(+) T lymphocytes, CD4(+dim) monocytes and some nonspecifically labeled cells are magnetically attracted to an analysis surface. Combining with CD3-Phycoerythrin (PE) labeling, only CD3(+)CD4(+) T lymphocytes are fluorescently labeled and visible in a fluorescent image of the analysis surface. The number of CD4(+) T lymphocytes is obtained by image analysis. Alternatively, CD3 immunomagnetic selection in combination with CD4 immunofluorescent labeling can also be applied for CD4(+) T lymphocytes enumeration.

RESULTS

The SP ICM system was compared with two single platform flow cytometer (SP FCM) methods: tetraCXP and TruCount methods. The SP ICM system has excellent precision, accuracy and linearity for CD4(+) T lymphocytes enumeration. Good correlations were obtained between the SP ICM and the SP FCM methods for blood specimens of 44 HIV(-) patients, and of 63 HIV(+) patients. Bland-Altman plots showed interchangeability between the SP ICM and the SP FCM methods.

CONCLUSIONS

The immunolabeling methods and the instrumentation are simple and easy-to-handle for less-trained operators. The SP ICM system is a good candidate for CD4(+) T lymphocytes enumeration in point-of-care settings of resource-constrained countries.

Progressive supravenous granulomatous nodular eruption in a human immunodeficiency virus-positive intravenous drug user treated with highly active antiretroviral therapy

We describe a 41-year-old human immunodeficiency virus-infected woman with a previous history of intravenous drug abuse, who developed multiple linear nodules following the superficial veins on both arms. Histopathological examination disclosed a dermal histiocytic inflammatory reaction with sarcoid-like granuloma formation occasionally showing an intracytoplasmic refractile material in the histiocytic cells. Nodular lesions developed progressively after starting on highly active antiretroviral therapy (HAART) which increased her CD4 cell count and suppressed her viral load. The appearance of latent inflammatory or autoimmune disease following HAART is a well-recognized phenomenon. We consider that this peculiar 'progressive supravenous granulomatous nodular eruption' should be included within the spectrum of the so-called immune reconstitution inflammatory syndrome.

Normalisation of CD4 counts in patients with HIV-1 infection and maximum virological suppression who are taking combination antiretroviral therapy: an observational cohort study

BACKGROUND

Combination antiretroviral therapy (cART) has been shown to reduce mortality and morbidity in patients with HIV. As viral replication falls, the CD4 count increases, but whether the CD4 count returns to the level seen in HIV-negative people is unknown. We aimed to assess whether the CD4 count for patients with maximum virological suppression (viral load <50 copies per mL) continues to increase with long-term cART to reach levels seen in HIV-negative populations.

METHODS

We compared increases in CD4 counts in 1835 antiretroviral-naive patients who started cART from EuroSIDA, a pan-European observational cohort study. Rate of increase in CD4 count (per year) occurring between pairs of consecutive viral loads below 50 copies per mL was estimated using generalised linear models, accounting for multiple measurements for individual patients.

FINDINGS

The median CD4 count at starting cART was 204 cells per microL (IQR 85-330). The greatest mean yearly increase in CD4 count of 100 cells per microL was seen in the year after starting cART. Significant, but lower, yearly increases in CD4 count, around 50 cells per microL, were seen even at 5 years after starting cART in patients whose current CD4 count was less than 500 cells per microL. The only groups without significant increases in CD4 count were those where cART had been taken for more than 5 years with a current CD4 count of more than 500 cells per microL, (current mean CD4 count 774 cells per microL; 95% CI 764-783). Patients starting cART with low CD4 counts (<200 cells per microL) had significant rises in CD4 counts even after 5 years of cART.

INTERPRETATION

Normalisation of CD4 counts in HIV-infected patients for all infected individuals might be achievable if viral suppression with cART can be maintained for a sufficiently long period of time.

Late Presentation of HIV-Infected Individuals

Late presentation remains a major concern despite the dramatically improved prognosis realized by ART. We define a first presentation for HIV care during the course of HIV infection as ‘late’ if an AIDS-defining opportunistic disease is apparent, or if CD4+ T-cells are <200/μl. In the Western world, approximately 10 and 30% of HIV-infected individuals still present with CD4+ T-cells <50 and <200/μl, respectively; estimates are substantially higher for developing countries. Diagnosis and treatment of opportunistic diseases and intense supportive in-hospital care take precedence over ART. Benefits of starting ART without delay, that is, when opportunistic diseases are still active, include faster resolution of opportunistic diseases and a decreased risk of recurrence. The downside of starting ART without delay could include toxicity, drug interactions and immune reconstitution inflammatory syndrome (IRIS). Among asymptomatic or oligosymptomatic individuals presenting late, where ART and primary prophylaxis are initiated, ∼10–20% will become symptomatic from drug toxicity or undiagnosed opportunistic complications, including IRIS, which require appropriate therapies. In this review we describe late presentation to HIV care, the scale of the problem, the evaluation of a late-presenting patient and challenges associated with initiation of potent anti-retroviral therapy (ART) in the setting of acute opportunistic infections and other comorbidities.

CD4+ T-Cell Count Increase in HIV-1-Infected Patients with Suppressed Viral Load Within 1 year after start of antiretroviral therapy

Background

CD4+ T-cell recovery in patients with continuous suppression of plasma HIV-1 viral load (VL) is highly variable. This study aimed to identify predictive factors for long-term CD4+ T-cell increase in treatment-naive patients starting combination antiretroviral therapy (cART).

Methods

Treatment-naive patients in the Swiss HIV Cohort Study reaching two VL measurements <50 copies/ml >3 months apart during the 1st year of cART were included ( n=1,816 patients). We studied CD4+ T-cell dynamics until the end of suppression or up to 5 years, subdivided into three periods: 1st year, years 2–3 and years 4–5 of suppression. Multiple median regression adjusted for repeated CD4+T-cell measurements was used to study the dependence of CD4+ T-cell slopes on clinical covariates and drug classes.

Results

Median CD4+ T-cell increases following VL suppression were 87, 52 and 19 cells/μl per year in the three periods. In the multiple regression model, median CD4+ T-cell increases over all three periods were significantly higher for female gender, lower age, higher VL at cART start, CD4+ T-cell <650 cells/μ l at start of the period and low CD4+ T-cell increase in the previous period. Patients on tenofovir showed significantly lower CD4+T-cell increases compared with stavudine.

Conclusions

In our observational study, long-term CD4+ T-cell increase in drug-naive patients with suppressed VL was higher in regimens without tenofovir. The clinical relevance of these findings must be confirmed in, ideally, clinical trials or large, collaborative cohort projects but could influence treatment of older patients and those starting cART at low CD4+ T-cell levels.

Predictors of disease progression in HIV infection: a review

During the extended clinically latent period associated with Human Immunodeficiency Virus (HIV) infection the virus itself is far from latent. This phase of infection generally comes to an end with the development of symptomatic illness. Understanding the factors affecting disease progression can aid treatment commencement and therapeutic monitoring decisions. An example of this is the clear utility of CD4+ T-cell count and HIV-RNA for disease stage and progression assessment. Elements of the immune response such as the diversity of HIV-specific cytotoxic lymphocyte responses and cell-surface CD38 expression correlate significantly with the control of viral replication. However, the relationship between soluble markers of immune activation and disease progression remains inconclusive. In patients on treatment, sustained virological rebound to >10,000 copies/mL is associated with poor clinical outcome. However, the same is not true of transient elevations of HIV RNA (blips). Another virological factor, drug resistance, is becoming a growing problem around the globe and monitoring must play a part in the surveillance and control of the epidemic worldwide. The links between chemokine receptor tropism and rate of disease progression remain uncertain and the clinical utility of monitoring viral strain is yet to be determined. The large number of confounding factors has made investigation of the roles of race and viral subtype difficult, and further research is needed to elucidate their significance. Host factors such as age, HLA and CYP polymorphisms and psychosocial factors remain important, though often unalterable, predictors of disease progression. Although gender and mode of transmission have a lesser role in disease progression, they may impact other markers such as viral load. Finally, readily measurable markers of disease such as total lymphocyte count, haemoglobin, body mass index and delayed type hypersensitivity may come into favour as ART becomes increasingly available in resource-limited parts of the world. The influence of these, and other factors, on the clinical progression of HIV infection are reviewed in detail, both preceding and following treatment initiation.

HIV patients developing primary CNS lymphoma lack EBV-specific CD4+ T cell function irrespective of absolute CD4+ T cell counts

BACKGROUND

In chronic HIV infection, antiretroviral therapy-induced normalization of CD4(+) T cell counts (immune reconstitution [IR]) is associated with a decreased incidence of opportunistic diseases. However, some individuals remain at risk for opportunistic diseases despite prolonged normalization of CD4(+) T cell counts. Deficient Epstein-Barr virus (EBV)-specific CD4(+) T cell function may explain the occurrence of EBV-associated opportunistic malignancy-such as primary central nervous system (PCNS) lymphoma-despite recovery of absolute CD4(+) T cell counts.

METHODS AND FINDINGS

Absolute CD4(+) T cell counts and EBV-specific CD4(+) T cell-dependent interferon-gamma production were assessed in six HIV-positive individuals prior to development of PCNS lymphoma ("cases"), and these values were compared with those in 16 HIV-infected matched participants with no sign of EBV-associated pathology ("matched controls") and 11 nonmatched HIV-negative blood donors. Half of the PCNS lymphoma patients fulfilled IR criteria (defined here as CD4(+) T cell counts >or=500/microl blood). EBV-specific CD4(+) T cells were assessed 0.5-4.7 y prior to diagnosis of lymphoma. In 0/6 cases versus 13/16 matched controls an EBV-specific CD4(+) T cell response was detected (p = 0.007; confidence interval for odds ratio [0-0.40]). PCNS lymphoma patients also differed with regards to this response significantly from HIV-negative blood donors (p < 0.001, confidence interval for odds ratio [0-0.14]), but there was no evidence for a difference between HIV-negative participants and the HIV-positive matched controls (p = 0.47).

CONCLUSIONS

Irrespective of absolute CD4(+) T cell counts, HIV-positive patients who subsequently developed PCNS lymphoma lacked EBV-specific CD4(+) T cell function. Larger, ideally prospective studies are needed to confirm these preliminary data, and clarify the impact of pathogen-specific versus surrogate marker-based assessment of IR on clinical outcome.

Problems and emerging approaches in HIV/AIDS vaccine development

According to recent estimates, 39.5 million people have been infected with HIV and 2.9 million have already died. The effect of HIV infection on individuals and communities is socially and economically devastating. Although antiretroviral drugs have had a dramatically beneficial impact on HIV-infected individuals who have access to treatment, it has had a negligible impact on the global epidemic. Therefore, the need for an efficacious HIV/AIDS vaccine remains the highest priority of the world HIV/AIDS agenda. The generation of a vaccine against HIV/AIDS has turned out to be extremely challenging, as indicated by > 20 years of unsuccessful attempts. This review discusses the major challenges in the field and key experimental evidence providing a rationale for the use of non-structural HIV proteins, such as Rev, Tat and Nef, either in the native form or expressed by viral vectors such as a replicating adeno-vector. These non-structural proteins alone or in combination with modified structural HIV-1 Env proteins represent a novel strategy for both preventative and therapeutic HIV/AIDS vaccine development.