Profile of immunologic recovery in HIV-infected Ugandan adults after antiretroviral therapy

Longitudinal effect of CD4 by cotrimoxazole use on malaria incidence among HIV-infected Ugandan adults on antiretroviral therapy: a randomized controlled study

Background

The effect of CD4 count on malaria incidence in HIV infected adults on antiretroviral therapy (ART) was assessed in the context of a randomized controlled trial on the effect of stopping cotrimoxazole (CTX).

Methods

This study presents a sub-analysis of the COSTOP trial (ISRCTN44723643) which was carried out among HIV-infected Ugandan adults stable on ART with CD4 counts ≥250 cells/µl. Participants were randomized (1:1) to continue CTX or stop CTX and receive matching placebo, and were followed up for a minimum of 1 year (median 2.5 years). CD4 counts were measured at baseline, 3 months and then every 6 months. Clinical malaria was defined as fever and a positive blood slide. First, the relationship between current CD4 count during follow-up and malaria among participants on placebo was examined; using random effects Poisson regression to account for repeated episodes. Second, the effect of CD4 count at enrolment, CD4 count at ART initiation, and CD4 count during follow-up on malaria, was assessed within each trial arm; to examine whether the effect of CD4 count differed by CTX use.

Results

2180 participants were enrolled into the COSTOP trial. The incidence of clinical malaria was approximately four episodes/100 person years in the CTX arm and 14 episodes/100 person years in the placebo arm. There was no evidence of an association of current CD4 and clinical malaria incidence (P = 0.56), or parasitaemia levels (P = 0.24), in the placebo arm. Malaria incidence did not differ by CD4 count at ART initiation, enrolment or during follow up, irrespective of CTX use. When compared with participants in the lowest CD4 stratum, rate ratios within each trial arm were all close to 1, and P values were all above P = 0.30.

Conclusions

The immune status of HIV infected participants who are stable on ART as measured by CD4 count was not associated with malaria incidence and did not modify the effect of stopping CTX on malaria. The decision of whether to stop or continue CTX prophylaxis for malaria in HIV infected individuals who are stable on ART should not be based on CD4 counts alone.

COSTOP trial registration number ISRCTN44723643

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1426-z) contains supplementary material, which is available to authorized users.

Poor immunological recovery among severely immunosuppressed antiretroviral therapy-naïve Ugandans

Introduction

CD4 T lymphocytes remain the surrogate measure for monitoring HIV progress in resource-limited settings. The absolute CD4 cell counts form the basis for antiretroviral therapy (ART) initiation and monitoring among HIV-infected adults. However, the rate of CD4 cell change differs among patients, and the factors responsible are inadequately documented.

Objective

This study investigated the relationship between HIV severity and ART outcomes among ART-naïve Ugandans, with the primary outcome of complete immunological recovery among patients of different baseline CD4 counts.

Methods

Patients’ records at two HIV/ART sites – the Joint Clinic Research Centre (JCRC) in the Kampala region and Mbarara Hospital in Western Uganda – were reviewed. Records of 426 patients – 68.3% female and 63.2% from JCRC – who initiated ART between 2002 and 2007 were included. HIV severity was based on baseline CD4 cell counts, with low counts considered as severe immunosuppression, while attaining 418 CD4 cells/μL signified complete immunological recovery. Incidence rates of complete immunological recovery were calculated for, and compared between baseline CD4 cell categories: <50 with ≥50, <100 with ≥100, <200 with ≥200, and ≥200 with ≥250 cells/μL.

Results

The incidence of complete immunological recovery was 158 during 791.9 person-years of observation, and patients with baseline CD4 ≥ 200 cells/μL reached the end point of immunological recovery 1.89 times faster than the patients with baseline CD4 < 200 cells/μL. CD4 cell change also differed by time, sex, and site, with a faster increase observed during the first year of treatment. CD4 cell increase was faster among females, and among patients from Mbarara.

Conclusion

Initiating ART at an advanced HIV stage was the main reason for poor immunological recovery among Ugandans. Earlier ART initiation might lead to better immunological responses.

High T-cell immune activation and immune exhaustion among individuals with suboptimal CD4 recovery after 4 years of antiretroviral therapy in an African cohort

BACKGROUND

Antiretroviral therapy (ART) partially corrects immune dysfunction associated with HIV infection. The levels of T-cell immune activation and exhaustion after long-term, suppressive ART and their correlation with CD4 T-cell count reconstitution among ART-treated patients in African cohorts have not been extensively evaluated.

METHODS

T-cell activation (CD38+HLA-DR+) and immune exhaustion (PD-1+) were measured in a prospective cohort of patients initiated on ART; 128 patient samples were evaluated and subcategorized by CD4 reconstitution after long-term suppressive treatment: Suboptimal [median CD4 count increase 129 (-43-199) cells/μl], N = 34 ], optimal [282 (200-415) cells/μl, N = 64] and super-optimal [528 (416-878) cells/μl, N = 30].

RESULTS

Both CD4+ and CD8 T-cell activation was significantly higher among suboptimal CD4 T-cell responders compared to super-optimal responders. In a multivariate model, CD4+CD38+HLADR+ T-cells were associated with suboptimal CD4 reconstitution [AOR, 5.7 (95% CI, 1.4-23, P = 0.014)]. T-cell exhaustion (CD4+PD1+ and CD8+PD1+) was higher among suboptimal relative to optimal (P < 0.001) and super-optimal responders (P < 0.001). T-cell exhaustion was significantly associated with suboptimal responders [AOR, 1.5 (95%CI, 1.1-2.1), P = 0.022].

CONCLUSION

T-cell activation and exhaustion persist among HIV-infected patients despite long-term, sustained HIV-RNA viral suppression. These immune abnormalities were associated with suboptimal CD4 reconstitution and their regulation may modify immune recovery among suboptimal responders to ART.

CD8 T-Cell Responses before and after Structured Treatment Interruption in Ugandan Adults Who Initiated ART with CD4 T Cells <200 Cell/μL: The DART Trial STI Substudy

Objective. To better understand attributes of ART-associated HIV-induced T-cell responses that might be therapeutically harnessed. Methods. CD8(+) T-cell responses were evaluated in some HIV-1 chronically infected participants of the fixed duration STI substudy of the DART trial. Magnitudes, breadths, and functionality of IFN-γ and Perforin responses were compared in STI (n = 42) and continuous treatment (CT) (n = 46) before and after a single STI cycle when the DART STI trial was stopped early due to inferior clinical outcome in STI participants. Results. STI and CT had comparable magnitudes and breadths of monofunctional CD8(+)IFNγ(+) and CD8(+)Perforin(+) responses. However, STI was associated with significant decline in breadth of bi-functional (CD8(+)IFNγ(+)Perforin(+)) responses; P = .02, Mann-Whitney test. Conclusions. STI in individuals initiated onto ART at <200 CD4(+) T-cell counts/μl significantly reduced occurrence of bifunctional CD8(+)IFNγ(+)/Perforin(+) responses. These data add to others that found no evidence to support STI as a strategy to improve HIV-specific immunity during ART.

Therapeutic immunization in HIV infected Ugandans receiving stable antiretroviral treatment: a Phase I safety study

Therapeutic immunizations in HIV infection may boost immunity during antiretroviral treatment. We report on the first therapeutic vaccine trial in Uganda, Africa. This open label Phase I trial was designed to assess the safety, tolerability and immunogenicity of a therapeutic HIV-1 vaccine candidate. Thirty HIV positive volunteers receiving a stable regimen of antiretroviral therapy with CD4 counts >400 were recruited for the safety evaluation of LFn-p24C, a detoxified anthrax-derived polypeptide fused to the subtype C HIV gag protein p24. The vaccine was well tolerated and HIV RNA levels remained undetectable following three immunizations. CD4 counts in vaccine recipients were significantly higher compared to the control individuals after 12 months. HIV-specific responses were associated with higher gain in CD4 counts following LFn-p24C immunizations. Volunteers were subsequently asked to undergo a 30-day period of observed treatment interruption. 8/24 (30%) individuals showed no evidence of viral rebound during treatment interruption. All demonstrated prompt suppression of viral load following resumption of ART. Our data demonstrate the safety of LFn-p24C and suggest that adjunct therapeutic immunization may benefit select individuals in further boosting an immune response.

Daily co-trimoxazole prophylaxis in severely immunosuppressed HIV-infected adults in Africa started on combination antiretroviral therapy: an observational analysis of the DART cohort

BACKGROUND

Co-trimoxazole prophylaxis can reduce mortality from untreated HIV infection in Africa; whether benefits occur alongside combination antiretroviral therapy (ART) is unclear. We estimated the effect of prophylaxis after ART initiation in adults.

METHODS

Participants in our observational analysis were from the DART randomised trial of management strategies in HIV-infected, symptomatic, previously untreated African adults starting triple-drug ART with CD4 counts lower than 200 cells per muL. Co-trimoxazole prophylaxis was not routinely used or randomly allocated, but was variably prescribed by clinicians. We estimated effects on clinical outcomes, CD4 cell count, and body-mass index (BMI) using marginal structural models to adjust for time-dependent confounding by indication. DART was registered, number ISRCTN13968779.

FINDINGS

3179 participants contributed 14 214 years of follow-up (8128 [57%] person-years on co-trimoxazole). Time-dependent predictors of co-trimoxazole use were current CD4 cell count, haemoglobin concentration, BMI, and previous WHO stage 3 or 4 events on ART. Present prophylaxis significantly reduced mortality (odds ratio 0.65, 95% CI 0.50-0.85; p=0.001). Mortality risk reduction on ART was substantial to 12 weeks (0.41, 0.27-0.65), sustained from 12-72 weeks (0.56, 0.37-0.86), but not evident subsequently (0.96, 0.63-1.45; heterogeneity p=0.02). Variation in mortality reduction was not accounted for by time on co-trimoxazole or current CD4 cell count. Prophylaxis reduced frequency of malaria (0.74, 0.63-0.88; p=0.0005), an effect that was maintained with time, but we observed no effect on new WHO stage 4 events (0.86, 0.69-1.07; p=0.17), CD4 cell count (difference vs non-users, -3 cells per muL [-12 to 6]; p=0.50), or BMI (difference vs non-users, -0.04 kg/m(2) [-0.20 to 0.13); p=0.68].

INTERPRETATION

Our results reinforce WHO guidelines and provide strong motivation for provision of co-trimoxazole prophylaxis for at least 72 weeks for all adults starting combination ART in Africa.

FUNDING

UK Medical Research Council, the UK Department for International Development, the Rockefeller Foundation, GlaxoSmithKline, Gilead Sciences, Boehringer-Ingelheim, and Abbott Laboratories.

Infection with different hiv subtypes is associated with CD4 activation-associated dysfunction and apoptosis

Determination of HIV-1 subtype may be important in the management of HIV-infected individuals, particularly with regard to deciding the CD4 cell count at which to initiate antiretroviral therapy. Non-B subtypes, A and D, are prevalent in Uganda, and individuals infected with subtype D seem to have faster disease progression compared with those infected with subtype A. We examined the level of apoptosis in CD4+ T cells in a study cohort of volunteers infected with subtypes A and D infection. Although the levels of apoptosis in the activated CD4+ cells significantly decreased with viral suppression, CD4+ apoptosis in individuals infected with subtype D were found to be significantly higher compared with those infected with subtype A before antiretroviral treatment. Surface expression of PD-1 on CD4 cells in subtype D was substantially higher compared with that in subtype A (P = 0.03). This difference was not observed in the CD8 population (P > 0.05). Our findings suggest that the infecting HIV subtypes exert an independent influence on the disease outcome in response to antiretroviral treatment.

Protective antigen-independent CD8 T cell memory is maintained during {gamma}-herpesvirus persistence

Ag persistence during high-titer chronic viral infections induces CD8 T cell dysfunction and lack of Ag-independent CD8 T cell memory formation. However, we have a poor understanding of the generation and maintenance of CD8 T cell memory during asymptomatic persistent viral infections, particularly gamma-herpesvirus infections. In this study, we demonstrate that the continuous presence of cognate Ag in the host is not required for the maintenance of CD8 T cell memory during a persistent gamma-herpesvirus infection. Importantly, the Ag-independent CD8 T cell memory that is maintained during gamma-herpesvirus persistence has the capacity to survive long-term under homeostatic conditions and to mount a protective recall response to a secondary encounter with the pathogen. These data highlight the ability of the immune system to maintain a population of protective memory CD8 T cells with capacity for long-term Ag-independent survival in the presence of systemic virus persistence.

Dynamics of T cell activation accompanying CD4 recovery in antiretroviral treated HIV-infected Ugandan children

Africans have elevated T cell activation compared to residents of Europe or the USA. Levels of T cell activation also correlate with disease progression in HIV-infected individuals. We sought to determine if treatment with antiretroviral therapy (ART) would reduce levels of T cell activation (CD38 and HLADR co-expression) in HIV-infected Ugandan children. The median CD8+ T cell activation level among 199 ART-treated children (30%) was lower than in 57 ART-naïve children (45%, p<0.001), but remained higher than in 30 HIV-uninfected children (18%, p<0.001). Among ART-treated children, CD4% was inversely correlated with both CD8- (rho=-0.61, p<0.001) and CD8+ (rho=-0.38, p<0.001) T cell activation. Prospectively, CD4 recovery correlated with post-treatment CD8+ T cell activation level (p=0.008). Our data suggest that significant decreases in T cell activation accompany CD4 recovery in ART-treated HIV-infected African children, to levels that approach but do not reach those of uninfected children.

The Distribution and Immune Profile of T Cell Subsets in HIV-Infected Children from Uganda

Abstract T cell activation is an important mechanism in HIV-associated immune depletion. We have previously demonstrated an association between the hyperactivation of CD4(+) and CD8(+) T cells and low CD4 status in HIV-infected Ugandan children. In this study, we explore differences in activation between naive and memory T cells in HIV-infected Ugandan children. A significant correlation between CD4- and CD8-mediated immune activation and CD4 status was observed only in the memory T cells. Antiretroviral (ART) untreated and treated HIV-positive and HIV-negative children displayed similar profiles of activation and distribution within the CD4(+) naive T cells. In contrast, significantly higher immune activation of the memory CD4(+) T cell subset was seen in ART-untreated children when compared to ART-treated or HIV-negative children. ART-mediated viral suppression led to the correction of CD4(+) immune activation to levels seen in uninfected children but did not increase the size of the memory CD4(+) T cell population. High levels of CD8(+) immune activation were also found in both naive and memory cell subsets. Antiretroviral treatment led to the normalization of CD8(+) T cell activation but did not correct the distribution of naive CD8(+) T cells. We also assessed PD-1 expression on CD8(+) T cells as a measure of immune dysfunction. Upregulation of PD-1 was highest in untreated children but persisted in ART-treated children compared to uninfected children. The mechanisms of immunopathogenesis in pediatric HIV infection likely involve distinct contributions from individual naive and memory T cells subsets.

AIDSVAX immunization induces HIV-specific CD8+ T-cell responses in high-risk, HIV-negative volunteers who subsequently acquire HIV infection

Correlates of immune protection from HIV vaccines remain undefined. The first HIV vaccine efficacy trial in the US and Europe VAX004, was designed to assess whether rgp120 envelope subunits (AIDSVAX B/B, VaxGen) can induce partial or complete protection from HIV-1 infection. No effectiveness in the reduction of either the acquisition of infection or levels of plasma viremia after HIV infection was noted. We found evidence of vaccine-specific CD8+ T cells in volunteers who received the vaccine, regardless of behavioral risk. Surprisingly, the CD8-response is significantly higher in participants who would go on to contract HIV infection. These results suggest that AIDSVAX immunization may boost preexisting immune responses-due to pre-infection exposure, and a vaccine-induced immune profile may serve as a biological marker for HIV susceptibility.