Immune and virological benefits of 10 years of permanent viral control with antiretroviral therapy

Association of HIV low-level viremia with CD4 count recovery among persons living with HIV during antiretroviral therapy in Dehong Prefecture, Southwest China in 2008-2021: a longitudinal study

BACKGROUND

The impact of human immunodeficiency virus (HIV) low-level viremia (LLV) on CD4 + T lymphocyte (CD4) cell count recovery during antiretroviral therapy (ART) remains unknown in China. This study aimed to investigate the association between LLV and CD4 count recovery among adults on ART in Southwest China.

METHODS

A longitudinal cohort study of persons living with HIV (PLHIV) were conducted in Dehong Prefecture, Southwest China. Incidence of CD4 count recovery (CD4 cell count ≥ 500 cells/µl) was calculated for each follow-up year and characteristics of LLV (VL between 50 and 999 copies/ml) were described. Group-based trajectory model (GBTM) was used to identify and characterize the trajectories of CD4 cell count and VL during follow up. Longitudinal associations between LLV and CD4 count recovery were examined using a generalized estimating equation (GEE) with LLV as a time-updated variable.

RESULTS

The study included a total of 7,485 PLHIV who received ART between 2008 and 2021 in Dehong. The median follow-up duration was 8.5 years. At baseline, the participants had a median age of 36 years, with males accounting for 60.5%. The median CD4 cell count at baseline was 268 cells/µl. Results of GBTM demonstrated that 730 patients (9.8%) experience LLV trajectories and 2,125 patients (28.4%) reached CD4 count recovery during follow-up. Compared to participants with the trajectory of VL < 50 copies/ml, the probability of CD4 count recovery were lower among participants with the trajectories of LLV 50-199 copies/ml (adjusted odds ratio [aOR] 0.69, 95% confidence interval [CI] 0.63-0.76) and LLV 200-999 copies/ml (aOR 0.51, 95% CI 0.45-0.59), CONCLUSION: Sustained LLV is associated with poorer CD4 recovery among HIV patients who are receiving ART. Interventions to ensure that PLHIV maintain durably undetectable VL during treatment should be prioritized to achieve immune recovery.

Enhanced Gut-Homing Dynamics and Pronounced Exhaustion of Mucosal and Blood CD4+ T Cells in HIV-Infected Immunological Non-Responders

Immunological non-responders (INR), a subgroup of people living with HIV (PLHIV) who fail to restore CD4⁺ T cell numbers upon effective antiretroviral treatment, have impaired gut mucosal barrier function and an inferior clinical prognosis compared with immunological responders (IR). The contribution of gut-homing and exhaustion of mucosal T cells to the INR phenotype was previously unknown. Flow cytometry analysis of mononuclear cells from peripheral blood and ileal and colonic lamina propria showed that INR had higher fractions of gut-homing CD4⁺ T cells in blood compared with IR. In addition, gut-homing cells were more likely to display signs of exhaustion in INR. The increased CD4⁺ T cell exhaustion in INR was ubiquitous and not restricted to subpopulations defined by activation, differentiation or regulatory T cell markers. In INR, colon CD4⁺ T cell exhaustion correlated negatively with the fraction of CD4⁺ T cells in the same compartment, this was not apparent in the ileum. The fraction of exhausted mucosal CD4⁺ T cells correlated with I-FABP and REG3α, markers of enterocyte damage. We conclude that alterations of gut-homing and exhaustion of T cells may contribute to impaired gut immune and barrier functions associated with immunological non-response in PLHIV.

Role of CD4+ T Cells in the Control of Viral Infections: Recent Advances and Open Questions

CD4+ T cells orchestrate adaptive immune responses through their capacity to recruit and provide help to multiple immune effectors, in addition to exerting direct effector functions. CD4+ T cells are increasingly recognized as playing an essential role in the control of chronic viral infections. In this review, we present recent advances in understanding the nature of CD4+ T cell help provided to antiviral effectors. Drawing from our studies of natural human immunodeficiency virus (HIV) control, we then focus on the role of high-affinity T cell receptor (TCR) clonotypes in mediating antiviral CD4+ T cell responses. Last, we discuss the role of TCR affinity in determining CD4+ T cell differentiation, reviewing the at times divergent studies associating TCR signal strength to the choice of a T helper 1 (Th1) or a T follicular helper (Tfh) cell fate.

A comparative analysis of blood pressure in HIV-infected patients versus uninfected controls residing in Sub-Saharan Africa: a narrative review

Elevated blood pressure (BP) is an important risk factor for cardiovascular disease and mortality in Sub-Saharan Africa (SSA). We reviewed the literature comparing BP in treated HIV-infected populations against untreated and/or uninfected controls from SSA. We conducted a narrative review through PubMed and EBSCO Discovery Service to determine estimates of raised BP and hypertension in HIV-infected patients versus untreated/uninfected controls (1 January 2005 to 31 July 2019 and 9 May 2020). We included 19 eligible studies that compared treated HIV-infected with untreated and/or uninfected controls. In studies comparing treated HIV-infected patients to uninfected controls, studies including 6882 (56.30%) and 21,819 (79.2%) participants reported lower BP and hypertension prevalence, respectively in HIV-infected patients; whereas studies including 753 (6.16%) and 3553 (12.9%) participants showed a higher BP and hypertension prevalence. Lastly, 4588 (37.54%) and 2180 (7.91%) participants showed no difference in BP and the prevalence of hypertension. When comparing BP of treated versus untreated HIV-infected patients, studies including 5757 (44.2%) patients reported lower BP in treated patients; while studies with 200 (1.53%) patients showed higher BP and 7073 (54.28%) showed no difference in BP. For hypertension status, studies with 4547 (74.5%) patients reported a lower prevalence of hypertension in treated patients; whereas studies with 598 (9.80%) patients showed higher prevalence; and 959 (15.7%) no difference in prevalence between treated versus untreated HIV-infected patients. In studies conducted in Sub-Saharan Africa, the majority of the findings indicate lower blood pressure and/or prevalence of hypertension in treated HIV-infected individuals compared to untreated and uninfected controls.

Short Communication: Extremely Severe CD4 Lymphopenia During HIV-1 Primary Infection

We report the case of a patient with a very profound CD4 T cell lymphopenia <20 cells/mm³ in the context of a primary HIV-1 infection, associated with both delayed HIV-specific antibody and CD8 T cell responses. A long-term immune reconstitution was observed after immediate initiation of antiretroviral therapy.

The predictive role of CD4+ cell count and CD4/CD8 ratio in immune reconstitution outcome among HIV/AIDS patients receiving antiretroviral therapy: an eight-year observation in China

BACKGROUND

The immune reconstitution after initiation of highly active antiretroviral therapy (HAART) among HIV-infected individuals substantially affects patients' prognosis. However, the dynamic characteristics and predictors of reconstitution outcome remain unclear.

METHODS

In this study, the HIV/AIDS patients with sustained virological suppression (viral load < 50 copies/ml) after HAART were enrolled. The patients were subgrouped into immunological non-responders (INRs) (< 200 cells/μl), immunological inadequate responders (IIRs) (200 ~ 500 cells/μl) and immunological responders (IRs) (> 500 cells/μl) according to the CD4 cell count after two-year HAART. The immune reconstitution data based on the CD4⁺ and CD8⁺ cell counts with 8-year follow-up were collected for analysis.

RESULTS

The CD4⁺ cell counts in the immunological responders (IRs) were significantly higher than in the immunological non-responders (INRs) and immunological inadequate responders (IIRs) (P <  0.001). The overall CD4⁺ cell count and CD4/CD8 ratio in the IRs increased faster than the IIRs and INRs. The CD4⁺ cell count growth at 0.5 year and 1 year after HAART in the IRs was significantly higher than the IIRs and INRs. The ROC curve demonstrated that 1 year CD4⁺ cell count had the highest predictive value, with the best cut-off value of 188 cells/μl, the predictive sensitivity was 81.0%, the predictive specificity was 85.2%, false positive rate was 14.8%, false negative rate was 19.0%, positive predictive value (IR) was 63.0%, negative predictive value (INR) was 93.5%.

CONCLUSIONS

Taken together, our findings suggest that early initiation of HAART can reduce the immune reconstitution failure. The combination of baseline CD4⁺ cell count and baseline CD4/CD8 ratio may serve as a valid predictor of immune reconstitution prognosis after HAART.

CD4 recovery is associated with genetic variation in IFNγ and IL19 genes

Not all HIV-infected patients receiving cART are able to recover optimal CD4-T cell levels despite achieving undetectable viremia. We evaluated the potential association between polymorphisms (SNPs) in cytokines involved in immune response (IL15, IFNγ and IL19) and the failure to achieve optimal CD4 T-cells restoration after cART. For this, we carried out a retrospective study in 412 HIV-infected patients starting cART with CD4<200 cells/μL. These patients were classified as immunological non-responders (INR) if having a CD4 increase (ΔCD4) below 200 cells/μL after two years on successful cART. IL15, IFNγ and IL19 polymorphisms were genotyped using Sequenom's MassARRAY platform. We found 134 INR patients with a median [IQR] ΔCD4 = 133[73-174] cells/μL. In the multivariate analysis adjusted for age, sex, infection route, ethnic origin, hepatitis co-infection and HIV infection length, the AA genotype of the SNP rs2430561 in IFNγ (OR:2.01[1.13-3.56], p = 0.017) and the TT genotype of polymorphism rs2243191 in IL19 (OR:2.58 [1.17-5.68], p = 0.019) showed significant association with the INR status. Our results show that polymorphisms in IFNγ and IL19 genes significantly impacts in the probability of not achieving an optimal immune recovery in HIV-patients starting cART with CD4 T-cells <200 cells/μL. Thus, these SNPs could represent potential predictive markers of the immunodiscordant response.

Adult antiretroviral therapy guidelines 2017

These guidelines are intended as an update to those published in the Southern African Journal of HIV Medicine in 2014 and the update on when to initiate antiretroviral therapy in 2015. Since the release of the previous guidelines, the scale-up of antiretroviral therapy (ART) in southern Africa has continued. New antiretroviral drugs have become available with improved efficacy, safety and robustness. The guidelines are intended for countries in the southern African region, which vary between lower and middle income.

The investigation of CD4+T-cell functions in primary HIV infection with antiretroviral therapy

Human immunodeficiency virus (HIV) infection leads to reduced CD4T-cell counts and immune dysfunction. Initiation of antiretroviral therapy (ART) in HIV primary infection has been recommended to achieve an optimal clinical outcome, but a comprehensive study on restoration of CD4T-cell function in primary HIV-infected individuals with ART still needs to be eluciated. We investigated longitudinal changes in the CD4T-cell counts, phenotypes, and functions in HIV-infected individuals with early ART (initiated within 6 months after HIV infection) or later ART (initiated more than 12 months after HIV infection). Patients from early ART and later ART groups had received ART for at least 1 year. Individuals with early ART had more CD4T cells, a faster rate of CD4T-cell recovery than those receiving later ART; the levels of CD4T-cell activation and senescence were lower in early ART compared to those with later ART (P = .031; P = .016), but the activation was higher than normal controls (NC) (P = .001); thymic emigrant function was more upregulated in early ART than in later ART (P = .015), but still lower than NC (P = .027); proliferative capacity and interferon-γ secretion of CD4T cells were significantly decreased in primary infection (P < .001; P = .029), and early ART restored these CD4T-cell functions, there is no difference with NC, later ART could partially restore the functions of CD4T cells, but it remained lower than that of NC (P = .005; P = .019). Early ART could better improve CD4T-cell function.

Total HIV-1 DNA, a Marker of Viral Reservoir Dynamics with Clinical Implications

HIV-1 DNA persists in infected cells despite combined antiretroviral therapy (cART), forming viral reservoirs. Recent trials of strategies targeting latent HIV reservoirs have rekindled hopes of curing HIV infection, and reliable markers are thus needed to evaluate viral reservoirs. Total HIV DNA quantification is simple, standardized, sensitive, and reproducible. Total HIV DNA load influences the course of the infection and is therefore clinically relevant. In particular, it is predictive of progression to AIDS and death, independently of HIV RNA load and the CD4 cell count. Baseline total HIV DNA load is predictive of the response to cART. It declines during cART but remains quantifiable, at a level that reflects both the history of infection (HIV RNA zenith, CD4 cell count nadir) and treatment efficacy (residual viremia, cumulative viremia, immune restoration, immune cell activation). Total HIV DNA load in blood is also predictive of the presence and severity of some HIV-1-associated end-organ disorders. It can be useful to guide individual treatment, notably, therapeutic de-escalation. Although it does not distinguish between replication-competent and -defective latent viruses, the total HIV DNA load in blood, tissues, and cells provides insights into HIV pathogenesis, probably because all viral forms participate in host cell activation and HIV pathogenesis. Total HIV DNA is thus a biomarker of HIV reservoirs, which can be defined as all infected cells and tissues containing all forms of HIV persistence that participate in pathogenesis. This participation may occur through the production of new virions, creating new cycles of infection and disseminating infected cells; maintenance or amplification of reservoirs by homeostatic cell proliferation; and viral transcription and synthesis of viral proteins without new virion production. These proteins can induce immune activation, thus participating in the vicious circle of HIV pathogenesis.

Baseline Naive CD4+ T-cell Level Predicting Immune Reconstitution in Treated HIV-infected Late Presenters

Background:

Among HIV-infected patients initiating antiretroviral therapy (ART), early changes in CD4+ T-cell subsets are well described. However, HIV-infected late presenters initiating treatment present with a suboptimal CD4+ T-cell reconstitution and remain at a higher risk for AIDS and non-AIDS events. Therefore, factors associated with CD4+ T-cell reconstitution need to be determined in this population, which will allow designing effective immunotherapeutic strategies.

Methods:

Thirty-one adult patients with baseline CD4+ T-cell count <350 cells/mm³ exhibiting viral suppression after ART initiation were followed in the HIV/AIDS research center of Peking Union Medical College Hospital in Beijing, China, from October 2002 to September 2013. Changes in T-cell subsets and associated determinants were measured.

Results:

Median baseline CD4+ T-cell count was 70 cells/mm³. We found a biphasic reconstitution of T-cell subsets and immune activation: a rapid change during the first 6 months followed by a more gradual change over the subsequent 8 years. Baseline CD4+ T-cell count >200 cells/mm³ in comparison to CD4+ T-cell count ≤200 cells/mm³ was associated with more complete immune Reconstitution (77.8% vs. 27.3% respectively; P = 0.017) and normalized CD4/CD8 ratio. We showed that the baseline percentage of naive CD4+ T-cell was a predictive marker for complete immune reconstitution (area under receiver operating characteristic curve 0.907), and 12.4% as cutoff value had a sensitivity of 84.6% and a specificity of 88.2%.

Conclusions:

Baseline naive CD4+ T-cell percentage may serve as a predictive marker for optimal immune reconstitution during long-term therapy. Such study findings suggest that increasing thymic output should represent an avenue to improve patients who are diagnosed late in the course of infection.

P2X7 Receptor Inhibition Improves CD34 T-Cell Differentiation in HIV-Infected Immunological Nonresponders on c-ART

Peripheral CD4+ T-cell levels are not fully restored in a significant proportion of HIV+ individuals displaying long-term viral suppression on c-ART. These immunological nonresponders (INRs) have a higher risk of developing AIDS and non-AIDS events and a lower life expectancy than the general population, but the underlying mechanisms are not fully understood. We used an in vitro system to analyze the T- and B-cell potential of CD34+ hematopoietic progenitor cells. Comparisons of INRs with matched HIV+ patients with high CD4+ T-cell counts (immune responders (IRs)) revealed an impairment of the generation of T-cell progenitors, but not of B-cell progenitors, in INRs. This impairment resulted in the presence of smaller numbers of recent thymic emigrants (RTE) in the blood and lower peripheral CD4+ T-cell counts. We investigated the molecular pathways involved in lymphopoiesis, focusing particularly on T-cell fate specification (Notch pathway), survival (IL7R-IL7 axis) and death (Fas, P2X7, CD39/CD73). P2X7 expression was abnormally strong and there was no CD73 mRNA in the CD34+ cells of INRs, highlighting a role for the ATP pathway. This was confirmed by the demonstration that in vitro inhibition of the P2X7-mediated pathway restored the T-cell potential of CD34+ cells from INRs. Moreover, transcriptomic analysis revealed major differences in cell survival and death pathways between CD34+ cells from INRs and those from IRs. These findings pave the way for the use of complementary immunotherapies, such as P2X7 antagonists, to restore T-cell lymphopoiesis in INRs.

High MIP-1β Levels in Plasma Predict Long-Term Immunological Nonresponse to Suppressive Antiretroviral Therapy in HIV Infection

BACKGROUND

HIV-infected patients who fail to reconstitute their CD4 T-cell counts during suppressive antiretroviral therapy (ART) have increased risk of both AIDS-related and non-AIDS-related morbidity and mortality. Improved understanding of immunological nonresponse (INR) is necessary to enable earlier clinical intervention.

METHODS

In a cohort of 112 HIV-infected patients starting ART, we performed a serial analysis of 32 plasma-soluble markers, assessed by multiplex cytokine and enzyme immunoassay. Samples were drawn pre-ART and during the first 3 years of treatment, with a final observation time of 8.4 years (interquartile range, 7.0-10.7 years) on ART. Long-term INR (LT-INR) was defined as failure to reach a CD4 T-cell count >350 cells per microliter. Marker stability was evaluated by parallel analysis of samples from ART-naïve and HIV-seronegative controls.

RESULTS

Baseline CD4 T-cell counts predicted subsequent LT-INR (n = 15) [odds ratio, 1.10 (95% confidence interval: 1.01 to 1.19) pr. 10 cells/μL reduction in CD4 count, P = 0.030] in the cohort as a whole, but not in patients with baseline CD4 counts <200 cells per microliter (n = 78). LT-INR was best characterized by elevated plasma levels of the CC chemokine macrophage inflammatory protein 1β (MIP-1β), both at baseline (pre-ART) and during ART. In patients with baseline CD4 counts <200 cells per microliter, baseline MIP-1β predicted LT-INR [odds ratio 1.23 (95% confidence interval: 1.02 to 1.47) per 10 pg/mL increase in MIP-1β, P = 0.029].

CONCLUSIONS

Elevated pre-ART levels of MIP-1β identified LT-INR patients who started ART at CD4 counts <200. INR was characterized by persistently high MIP-1β during suppressive ART. Thus, MIP-1β may be of use for early identification of LT-INR.

The CD4 slope can be a predictor of immunologic recovery in advanced HIV patients: a case-control study

BACKGROUND/AIMS

Advanced human immunodeficiency virus (HIV) infection, despite sustained viral suppression by highly active antiretroviral therapy (HAART), is a risk factor for poor immunologic recovery. However, some patients with advanced infection do show immunologic recovery. In this study, predictive factors of immunologic recovery were analyzed in advanced HIV patients showing sustained viral suppression.

METHODS

A case-control study was conducted in HIV-infected adult patients with HIV-1 RNA < 50 copies/mL maintained for 4 years or longer and who were receiving HAART. Advanced HIV infection was defined as a baseline CD4 T cell count < 200/mm(3). Immunologic responders were defined as patients showing immunologic recovery (CD4 T cell counts ≥ 500/mm(3) at 4 years with HAART). To analyze the CD4 T cell kinetics, the CD4 slope (monthly changes in the CD4 T cell count) was estimated for each patient using a linear regression between the CD4 T cell count and the time since HAART initiation.

RESULTS

Of 102 eligible patients, 73 had advanced HIV, and 33 (45.2%) showed immunologic recovery. The median CD4 slopes (cells/mm(3) per month) during 0 to 6 and 0 to 12 months of HAART in the 73 advanced patients were significantly higher in responders than in non-responders (0 to 6 months, 38.6 vs. 22.8; 0 to 12 months, 24.5 vs. 13.5). Multivariate analyses showed opportunistic infections at the start of HAART (adjusted odds ratio [OR], 0.28) and a CD4 slope ≥ 20 during 0 to 12 months of HAART (adjusted OR, 10.10) were independently associated with immunologic recovery.

CONCLUSIONS

The CD4 slope can be an early predictor of long-term immunologic recovery in advanced HIV patients.

Immune Reconstitution but Persistent Activation After 48 Weeks of Antiretroviral Therapy in Youth With Pre-Therapy CD4 >350 in ATN 061

BACKGROUND

Measures of immune outcomes in youth who initiate combination antiretroviral therapy (cART) early in HIV infection are limited.

DESIGN

Adolescent Trials Network 061 examined changes over 48 weeks of cART in T-cell subsets and markers of T-cell and macrophage activation in subjects with pre-therapy CD4 > 350 cells/mm. All subjects had optimal viral suppression from weeks 24 through 48.

METHODS

Subjects (n = 48) initiated cART with tenofovir/emtricitabine plus ritonavir-boosted atazanavir. Data were collected at baseline and weeks 12, 24, and 48. Trends were compared to uninfected controls.

RESULTS

Significant increases over 48 weeks were noted in all CD4 populations, including total, naive, central memory (CM), and effector memory RO (EM RO) and effector memory RA (EM RA), whereas numbers of CM and EM RO CD8 cells declined significantly. By week 48, CD4 naive cells were similar to controls, whereas CM CD4 cells remained significantly lower and EM RO and EM RA subsets were significantly higher. CD38 and HLA DR expression, both individually and when co-expressed, decreased over 48 weeks of cART on CD8 cells but remained significantly higher than controls at week 48. In contrast, markers of macrophage activation measured by sCD14 and sCD163 in plasma did not change with cART and were significantly higher than controls.

CONCLUSIONS

In youth initiating early cART, CD4 cell reconstitution is robust with decreases in CD8 cells. However, CD8 T-cell and macrophage activation persists at higher levels than uninfected controls.

Changes in cellular immune activation and memory T-cell subsets in HIV-infected Zambian children receiving HAART

BACKGROUND

Increased exposure to a broad array of pathogens in children residing in sub-Saharan Africa may lead to heightened immune activation and increased proportions of memory T cells. Changes in the size of these cellular subsets have implications for restoration of normal immune function after treatment with highly active antiretroviral therapy (HAART) and are not well characterized in young sub-Saharan African children.

METHODS

CD4⁺ and CD8⁺ T-cell subsets were measured by flow cytometry in 157 HIV-infected Zambian children before and at 3-month intervals during HAART for up to 30 months and in 34 control children at a single study visit.

RESULTS

Before HAART, HIV-infected children had higher levels of activated and effector memory (EM) CD4⁺ and CD8⁺ T cells, and lower levels of naive T cells and CD8⁺ T cells expressing IL-7Rα, compared with control children. The median duration of follow-up was 14.9 months (interquartile range, 6.4-23.2) among 120 HIV-infected children with at least 1 study follow-up visit. Levels of immune activation and EM CD4⁺ T cells declined within 6 months of HAART, but the percentages of EM CD4 T cells and effector CD8⁺ T cells remained elevated through 30 months of HAART. IL-7Rα-expressing CD8⁺ T cells increased with HAART, suggesting expansion of memory capacity.

CONCLUSIONS

HAART significantly reduced levels of immune activation and EM CD4⁺ T cells, and promoted reconstitution of naive T cells and IL-7Rα-expressing CD8⁺ T cells. However, persistently high levels of EM CD4⁺ T cells in HIV-infected children may reflect chronic perturbations in T-cell subset composition.

The future role of CD4 cell count for monitoring antiretroviral therapy

For more than two decades, CD4 cell count measurements have been central to understanding HIV disease progression, making important clinical decisions, and monitoring the response to antiretroviral therapy (ART). In well resourced settings, the monitoring of patients on ART has been supported by routine virological monitoring. Viral load monitoring was recommended by WHO in 2013 guidelines as the preferred way to monitor people on ART, and efforts are underway to scale up access in resource-limited settings. Recent studies suggest that in situations where viral load is available and patients are virologically suppressed, long-term CD4 monitoring adds little value and stopping CD4 monitoring will have major cost savings. CD4 cell counts will continue to play an important part in initial decisions around ART initiation and clinical management, particularly for patients presenting late to care, and for treatment monitoring where viral load monitoring is restricted. However, in settings where both CD4 cell counts and viral load testing are routinely available, countries should consider reducing the frequency of CD4 cell counts or not doing routine CD4 monitoring for patients who are stable on ART.

Failure to achieve a CD4+ cell count response on combination antiretroviral therapy despite consistent viral load suppression

OBJECTIVE

To assess CD4 cell count recovery in people severely immunosuppressed at start of antiretroviral therapy (ART) who achieve and maintain viral load suppression.

METHODS

Eligible participants from the UK Collaborative HIV Cohort Study started ART with at least three drugs after 1 January 2000. Participants were required to have pre-ART CD4 cell count below 100 cells/μl, at least 2 years of follow-up on ART, have achieved viral load suppression (≤ 50 copies/ml) by 9 months after starting ART and to have maintained this throughout follow-up. Participants were further required to be regularly engaged with care. We calculated the proportion of people who failed to achieve a CD4 cell count of more than 100, 150, 200, 350 and 500 cells/μl by the time of the last follow-up, or 5 years from start of ART, whichever occurred first (censoring date).

RESULTS

Of the 400 participants [median (interquartile range) pre-ART CD4 cell count of 38 (14-65) cells/μl], 2 (0.5%), 8 (2%), 28 (7%), 131 (33%) and 259 (65%) failed to achieve a CD4 cell count of more than 100, 150, 200, 350 and 500 cells/μl, by the censoring date, respectively. Kaplan-Meier estimates of the proportion of people reaching each CD4 cell count threshold after 1 year on ART were 88, 70, 50, 14 and 3%, respectively, and after 3 years on ART, 98, 95, 90, 59 and 25%, respectively. Median (interquartile range) follow-up on ART was 3.9 (2.7-4.8) years.

CONCLUSION

Given a person with pre-ART CD4 cell count below 100 cells/μl survives and maintains consistent viral load suppression on ART, there is over a 90% chance of reaching a CD4 cell count above 200 cells/μl by 3 years.

Modulation of Regulatory T-Cell Subsets in Very Long-Term Treated Aviremic HIV(+) Patients and Untreated Viremic Patients

Naïve, central- and effector-like memory regulatory T cells (Tregs) were evaluated in untreated and long-term antiretroviral-treated HIV⁺ patients that showed comparable CD4⁺ cell levels, while being, respectively, viremic and aviremic. In the untreated patients, the percentage of naïve-like Tregs was significantly increased to the detriment of central memory regulatory T cells. This redistribution of regulatory Treg subsets may contribute to explain the partially preserved CD4⁺ cell counts seen in these patients despite the ongoing viremia. On the contrary, in the long-term treated patients, the percentages of Treg subsets were similar to those of healthy donors, demonstrating a restored Treg homeostasis. The characterization of Treg subsets, rather than an evaluation of the total Treg population, may lead to a deeper understanding of the Treg role in HIV infection and therapy.

Synthetic HIV-1 matrix protein p17-based AT20-KLH therapeutic immunization in HIV-1-infected patients receiving antiretroviral treatment: A phase I safety and immunogenicity study

BACKGROUND

Therapeutic vaccination is a promising novel approach to treat HIV-1 infected people by boosting or redirecting immune system to neutralize critical HIV-1 antigens whose biological effects are relevant in the context of viral pathogenesis. With the aim to induce neutralizing antibodies to the matrix protein p17 we have developed a peptide-based immunogen (AT20-KLH) and evaluated its safety and immunogenicity.

METHODOLOGY

Twenty four asymptomatic HAART-treated HIV-1+ patients were enrolled in a phase I clinical study and were randomized to three groups: 2 groups were treated with five IM injection (Arm A: 25μg/inoculation; Arm B: 100μg/inoculation) at day (D) D0, D28, D56, D84 and D112; the control group (Arm C) were not injected. Safety was assessed by monitoring local and systemic adverse events (AEs), recorded till D168. Evaluation of immunogenicity was by titering antibodies at D0, D35, D56, D63, D84, D91, D112, D140 and D168 using ELISA.

RESULTS

In all, 105 local and systemic AEs were reported across the three groups. Most were mild and resolved without sequelae. Also the few unsolicited events, deemed unrelated to the study vaccines, caused no problems. No significant changes in the routine laboratory parameters, CD4 T-cell count or HIV-1 viremia were found. At the time of enrollment 23 out of 24 patients had no anti-AT20 antibodies, whereas 11 exhibited anti-p17 antibodies. Irrespective of the presence of preimmunization antibodies, all subjects developed high titers of anti-AT20 antibodies (GM 9775) in response to both AT20-KLH doses. These antibodies were also capable of recognizing AT20 within the p17 framework.

CONCLUSIONS

The AT20 peptide-based approach has allowed to redirect HAART-treated patients' humoral responses toward a previously untargeted hotspot of functional activity. Overall, the tested AT20-KLH doses were safe and well tolerated, supporting further exploration of AT20-KLH as an HIV-1 therapeutic vaccine candidate.

The Significance of Interferon-γ in HIV-1 Pathogenesis, Therapy, and Prophylaxis

Interferon-γ (IFNγ) plays various roles in the pathogenesis of HIV/AIDS. In an HIV-1 infected individual, the production of IFNγ is detected as early as the acute phase and continually detected throughout the course of infection. Initially produced to clear the primary infection, IFNγ together with other inflammatory cytokines are involved in establishing a chronic immune activation that exacerbates clinical diseases associated with AIDS. Unlike Type 1 IFNs, IFNγ has no direct antiviral activity against HIV-1 in primary cultures, as supported by the in vivo findings of IFNγ therapy in infected subjects. Results from both in vitro and ex vivo studies show that IFNγ can instead enhance HIV-1 replication and its associated diseases, and therapies aimed at decreasing its production are under consideration. On the other hand, IFNγ has been shown to enhance cytotoxic T lymphocytes and NK cell activities against HIV-1 infected cells. These activities are important in controlling HIV-1 replication in an individual and will most likely play a role in the prophylaxis of an effective vaccine against HIV-1. Additionally, IFNγ has been used in combination with HIV-1 vaccine to augment antiviral immunity. Technological advancements have focused on using IFNγ as a biological marker to analyze the type(s) of immunity generated by candidate HIV vaccines and the levels of immunity restored by anti-retroviral drug therapies or novel immunotherapies. Hence, in addition to its valuable ancillary role as a biological marker for the development of effective HIV-1 prophylactic and therapeutic strategies, IFNγ has a vital role in promoting the pathogenesis of HIV.

Restoration of CMV-specific-CD4 T cells with ART occurs early and is greater in those with more advanced immunodeficiency

Objectives

Restoration of Cytomegalovirus-specific-CD4 T cell (CMV-Sp-CD4) responses partly accounts for the reduction of CMV-disease with antiretroviral-therapy (ART), but CMV-Sp-CD4 may also drive immune activation and immunosenescence. This study characterized the dynamics of CMV-Sp-CD4 after ART initiation and explored associations with CD4 T cell recovery as well as frequency of naïve CD4 T cells at week 96.

Methods

Fifty HIV-infected, ART-naïve Thai adults with CD4 T cell count ≤350cells/µL and starting ART were evaluated over 96 weeks (ClinicalTrials.gov identifier NCT01296373). CMV-Sp-CD4 was detected by co-expression of CD25/CD134 by flow cytometry after CMV-antigen stimulation.

Results

All subjects were CMV sero-positive, 4 had quantifiable CMV-DNA (range 2.3-3.9 log₁₀ copies/mL) at baseline but none had clinically apparent CMV-disease. Baseline CMV-Sp-CD4 response was positive in 40 subjects. Those with CD4 T cell count <100cells/µL were less likely to have positive baseline CMV-Sp-CD4 response (P=0.003). Positive baseline CMV-Sp-CD4 response was associated with reduced odds of quantifiable CMV-DNA (P=0.022). Mean CD4 T cell increase at week 96 was 213 cells/µL. This was associated positively with baseline HIV-VL (P=0.001) and negatively with age (P=0.003). The frequency of CMV-Sp-CD4 increased at week 4 (P=0.008), then declined. Those with lower baseline CMV-Sp-CD4 (P=0.009) or CDC category C (P<0.001) had greater increases in CMV-Sp-CD4 at week 4. At week 96, CD4 T cell count was positively (P<0.001) and the frequency of CMV-Sp-CD4 was negatively (P=0.001) associated with the percentage of naïve CD4 T cells.

Conclusions

Increases in CMV-Sp-CD4 with ART occurred early and were greater in those with more advanced immunodeficiency. The frequency of CMV-Sp-CD4 was associated with reduced naïve CD4 T cells, a marker associated with immunosenescence.

Immune control of HIV-1 reservoirs

PURPOSE OF REVIEW

To discuss the recent major advances in the understanding of how host immune defenses contribute to HIV reservoir control.

RECENT FINDINGS

Immune control of HIV-1 reservoirs is a two-step process: viral replication activation from latent reservoirs followed by elimination of virus-expressing cells by the host. Environmental factors, such as pro-inflammatory type-I interferon, chemokines or cytokines, can facilitate HIV-1 replication, confer dormancy in CD4 cells or confer resistance to cytopathogenic effects of cytotoxic CD8 T cells. Therefore, they constitute a double-edged sword for immune control of HIV reservoirs. Concomitantly, adaptive immunity takes advantage of CD4 T-cell homeostatic mechanisms and can expose HIV-1 antigen-expressing cells to HIV-specific cytotoxic CD8 T cells, and limit virus spreading. These highly interconnected phenomena can lead to quasi-equilibrium between the HIV-1 reservoirs and host immune control that can serve as a model for the 'shock and kill' immune-based therapeutic strategies in play in the course of finding an HIV cure.

SUMMARY

Immune control of HIV reservoirs in CD4 T cells involves modulation of both HIV-1 latency and the continuous reseeding of the reservoir offering conceptual models that may advance HIV cure strategies.

Poor immune reconstitution in HIV-infected patients associates with high percentage of regulatory CD4+ T cells

CD4⁺ regulatory T cells (Tregs) are essential for the maintenance of the immune system's equilibrium, by dampening the activation of potential auto-reactive T cells and avoiding excessive immune activation. To correctly perform their function, Tregs must be maintained at the right proportion with respect to effector T cells. Since this equilibrium is frequently disrupted in individuals infected with the human immunodeficiency virus (HIV), we hypothesize that its deregulation could hamper immune reconstitution in patients with poor CD4⁺ T cell recovery under highly active antiretroviral therapy (HAART). We analysed Tregs percentages amongst CD4⁺ T cells in 53 HIV-infected patients under HAART, with suppression of viral replication and distinct levels of immune reconstitution. As controls, 51 healthy individuals were also analysed. We observed that amongst the patients with Nadir values (the lowest CD4⁺ T cell counts achieved) <200 cells/µL, the individuals with high Tregs percentages (≥10% of total CD4⁺ T cells) had the worse CD4⁺ T cell reconstitution. In accordance, the well-described direct correlation between the Nadir value and CD4⁺ T cell reconstitution is clearly more evident in individuals with high Tregs proportions. Furthermore, we observed a strong negative correlation between Tregs percentages and CD4⁺ T cell recovery among immunological non-responder HIV⁺ individuals. All together, this work shows that high Tregs frequency is an important factor associated with sub-optimal CD4⁺ T cell recovery. This is particularly relevant for immunological non-responders with low Nadir values. Our results suggest that the Tregs proportion might be of clinical relevance to define cut-offs for HAART initiation.

Long-term antiretroviral therapy initiated during primary HIV-1 infection is key to achieving both low HIV reservoirs and normal T cell counts

OBJECTIVES

To characterize viro-immunological outcomes following long-term combined antiretroviral therapy (cART) initiated during primary HIV infection (PHI) or chronic HIV infection (CHI) and to identify factors predictive of optimal viro-immunological responder (OVIR) status.

METHODS

This was a prospective, single-centre cohort study of HIV-1-infected patients on effective cART. Total cell-associated HIV DNA levels and T cell counts before and during treatment were used to identify factors predictive of OVIR status {i.e. low HIV DNA level [<2.3 log10 copies/10(6) peripheral blood mononuclear cells (PBMCs)], together with normalization of the absolute/relative CD4+ T cell counts and CD4+/CD8+ ratio}.

RESULTS

A total of 307 patients were enrolled, of whom 35 started cART during PHI (<4 months post-infection) and 272 during CHI. HIV DNA decay was modelled with a non-linear mixed-effects model that showed two phases of HIV DNA decay, both of which were significantly more pronounced in the PHI group. At the end of follow-up, after a median of 4 years of viral suppression (<50 copies/mL), HIV DNA levels were lower in the PHI group than in the CHI group (median = 2.15 versus 2.84 log10 copies/10(6) PBMCs; P< 0.0001). Immune reconstitution was more rapid and sustained in the PHI group (median = 883 versus 619 CD4+ cells/mm(3); 41% versus 31% CD4+; CD4+/CD8+ 1.31 versus 0.77; all P< 0.0001). Finally, OVIR status was obtained in 19/35 (54%) and 7/272 (3%) patients in the PHI and CHI groups (P< 0.0001), respectively. In a logistic regression analysis, cART initiation during PHI (OR = 16, 95% CI = 3.5-72.3) and HIV DNA level <3.3 log10 before treatment (OR = 4.8, 95% CI = 1.2-19.3) were independently predictive of OVIR status.

CONCLUSIONS

Initiating cART during PHI represents a major opportunity to reduce HIV reservoirs and achieve optimal immune reconstitution.

T-cell subset distribution in HIV-1-infected patients after 12 years of treatment-induced viremic suppression

OBJECTIVE

Residual immune activation and skewed T cell maturation may contribute to excess comorbidity and mortality in successfully treated HIV-infected patients, and long-term effects of combination antiretroviral therapy (cART) on immune reconstitution remain a debated issue. Quantitative T cell reconstitution and activation and its association with residual viremia in patients with 12 years of viremic suppression were investigated.

DESIGN

Blood samples collected cross-sectionally from 71 HIV-infected patients with cART-induced viremic suppression through 12 years were compared with samples from 16 healthy controls.

METHODS

Several different subsets of naive, memory, and activated T cells were analyzed in fresh whole blood by 6-color flowcytometry, and ultrasensitive quantification of HIV RNA was performed.

RESULTS

HIV-infected patients had lower absolute and relative CD4 T cell counts and higher absolute and relative CD8 T cell counts than controls. HIV-infected patients had lower concentrations of naive CD4 cells than controls, but proportions were similar. HIV-infected patients had higher concentrations of CD8 T cells than controls in all the examined subsets but only a higher proportion of CD8 cells in the intermediately differentiated and activated subsets. Residual viremia did not correlate to proportions of naive CD4, CD4 recent thymic emigrants, or activated CD8 T cells.

CONCLUSIONS

This study demonstrated some degree of T cell imbalance even after 12 years of successful cART. Large longitudinal studies are needed to establish whether these discrete changes have clinical relevance.

Viral, host and therapeutic factors affecting T-cell recovery in virologically controlled HIV patients

Despite suppressive combination antiretroviral therapy, a considerable proportion of HIV-infected patients do not achieve adequate immune recovery in terms of the CD4+ T-cell count, although they have controlled viremia values. Many questions remain for clinicians in the management of these patients, defined as immunological nonresponders, including questions about the mechanisms underlying the lack of immune restoration and possible therapeutic approaches to this particular group of patients.

HIV controllers maintain a population of highly efficient Th1 effector cells in contrast to patients treated in the long term

HIV controllers are rare individuals who spontaneously control HIV replication in the absence of antiretroviral therapy. To identify parameters of the CD4 response that may contribute to viral control rather than merely reflect a persistently low viremia, we compared the T helper profiles in two groups of patients with more than 10 years of viral suppression: HIV controllers from the Agence Nationale de Recherche sur le SIDA et les Hépatites Virales (ANRS) CO18 cohort (n = 26) and efficiently treated patients (n = 16). Cells specific for immunodominant Gag and cytomegalovirus (CMV) peptides were evaluated for the production of 10 cytokines and cytotoxicity markers and were also directly quantified ex vivo by major histocompatibility complex (MHC) class II tetramer staining. HIV controller CD4(+) T cells were characterized by a higher frequency of gamma interferon (IFN-γ) production, perforin(+)/CD107a(+) expression, and polyfunctionality in response to Gag peptides. While interleukin 4 (IL-4), IL-17, and IL-21 production did not differ between groups, the cells of treated patients produced more IL-10 in response to Gag and CMV peptides, pointing to persistent negative immunoregulation after long-term antiretroviral therapy. Gag293 tetramer-positive cells were detected at a high frequency (0.12%) and correlated positively with IFN-γ-producing CD4(+) T cells in the controller group (R = 0.73; P = 0.003). Tetramer-positive cells were fewer in the highly active antiretroviral therapy (HAART) group (0.04%) and did not correlate with IFN-γ production, supporting the notion of a persistent immune dysfunction in HIV-specific CD4(+) T cells of treated patients. In conclusion, HIV controllers maintained a population of highly efficient Th1 effectors directed against Gag in spite of a persistently low antigenemia, while patients treated in the long term showed a loss of CD4 effector functions.

Suboptimal immune reconstitution in vertically HIV infected children: a view on how HIV replication and timing of HAART initiation can impact on T and B-cell compartment

Today, HIV-infected children who have access to treatment face a chronic rather than a progressive and fatal disease. As a result, new challenges are emerging in the field. Recent lines of evidence outline several factors that can differently affect the ability of the immune system to fully reconstitute and to mount specific immune responses in children receiving HAART. In this paper, we review the underlying mechanisms of immune reconstitution after HAART initiation among vertically HIV-infected children analyzing the possible causes of suboptimal responses.

HIV RNA suppression and immune restoration: can we do better?

HAART has significantly changed the natural history of HIV infection: patients receiving antiretrovirals are usually able to control viremia, even though not all virological responders adequately recover their CD4+ count. The reasons for poor immune restoration are only partially known and they include genetic, demographic and immunologic factors. A crucial element affecting immune recovery is immune activation, related to residual viremia; indeed, a suboptimal virological control (i.e., low levels of plasma HIV RNA) has been related with higher levels of chronic inflammation and all-cause mortality. The sources of residual viremia are not yet completely known, even though the most important one is represented by latently infected cells. Several methods, including 2-LTR HIV DNA and unspliced HIV RNA measurement, have been developed to estimate residual viremia and predict the outcome of antiretroviral therapy. Considering that poor immunologic responders are exposed to a higher risk of both AIDS-related and non-AIDS-related diseases, there is a need of new therapeutic strategies, including immunomodulators and drugs targeting the latent viral reservoirs, in order to face residual viremia but also to “drive” the host immunologic responses.

Early and prolonged antiretroviral therapy is associated with an HIV-1-specific T-cell profile comparable to that of long-term non-progressors

BACKGROUND

Intervention with antiretroviral treatment (ART) and control of viral replication at the time of HIV-1 seroconversion may curtail cumulative immunological damage. We have therefore hypothesized that ART maintenance over a very prolonged period in HIV-1 seroconverters could induce an immuno-virological status similar to that of HIV-1 long-term non-progressors (LTNPs).

METHODOLOGY/PRINCIPAL FINDINGS

We have investigated a cohort of 20 HIV-1 seroconverters on long-term ART (LTTS) and compared it to one of 15 LTNPs. Residual viral replication and reservoirs in peripheral blood, as measured by cell-associated HIV-1 RNA and DNA, respectively, were demonstrated to be similarly low in both cohorts. These two virologically matched cohorts were then comprehensively analysed by polychromatic flow cytometry for HIV-1-specific CD4(+) and CD8(+) T-cell functional profile in terms of cytokine production and cytotoxic capacity using IFN-γ, IL-2, TNF-α production and perforin expression, respectively. Comparable levels of highly polyfunctional HIV-1-specific CD4(+) and CD8(+) T-cells were found in LTTS and LTNPs, with low perforin expression on HIV-1-specific CD8(+) T-cells, consistent with a polyfunctional/non-cytotoxic profile in a context of low viral burden.

CONCLUSIONS

Our results indicate that prolonged ART initiated at the time of HIV-1 seroconversion is associated with immuno-virological features which resemble those of LTNPs, strengthening the recent emphasis on the positive impact of early treatment initiation and paving the way for further interventions to promote virological control after treatment interruption.

Immune reconstitution under antiretroviral therapy: the new challenge in HIV-1 infection

Although highly active antiretroviral therapy has enabled constant progress in reducing HIV-1 replication, in some patients who are "aviremic" during treatment, the problem of insufficient immune restoration remains, and this exposes them to the risk of immune deficiency-associated pathologies. Various mechanisms may combine and account for this impaired immunologic response to treatment. A first possible mechanism is immune activation, which may be because of residual HIV production, microbial translocation, co-infections, immunosenescence, or lymphopenia per se. A second mechanism is ongoing HIV replication. Finally, deficient thymus output, sex, and genetic polymorphism influencing apoptosis may impair immune reconstitution. In this review we will discuss the tools at our disposal to identify the various mechanisms at work in a given patient and the specific therapeutic strategies we could propose based on this etiologic diagnosis.

Immune reconstitution after a decade of combined antiretroviral therapies for human immunodeficiency virus

The introduction of combined antiretroviral therapies (HAART) has reversed the fatal course of human immunodeficiency virus (HIV) infection. HAART controls virus production and, in most cases, allows the quantitative and functional immune defects caused by HIV to be reversed. Here, we review T cell homeostatic mechanisms that drive immune recovery. These homeostatic mechanisms, as well as differences in T cell antigen exposure, explain the distinct patterns of recovery for HIV-specific T cells versus T cells specific for other pathogens. Immune restoration during HAART can, however, have adverse effects. Immune restoration syndrome occurs in some patients as a result of successful but unbalanced immunity.

Long-term CD4+ lymphocyte response following HAART initiation in a U.S. Military prospective cohort

Background

Among HIV-infected persons initiating highly active antiretroviral therapy (HAART), early CD4+ lymphocyte count increases are well described. However, whether CD4+ levels continue to increase or plateau after 4-6 years is controversial.

Methods

To address this question and identify other determinants of CD4+ response, we analyzed data for 1,846 persons from a prospective HIV military cohort study who initiated HAART, who had post-HAART CD4+ measurements, and for whom HIV seroconversion (SC) date was estimated.

Results

CD4+ count at HAART initiation was ≤ 200 cells/mm³ for 23%, 201-349 for 31%, 350-499 for 27%, and ≥500 for 19%. The first 6 months post-HAART, the greatest CD4+ increases (93-151 cells) occurred, with lesser increases (22-36 cells/year) through the first four years. Although CD4+ changes for the entire cohort were relatively flat thereafter, HIV viral load (VL) suppressors showed continued increases of 12-16 cells/year. In multivariate analysis adjusting for baseline CD4+ and post-HAART time interval, CD4+ responses were poorer in those with: longer time from HIV SC to HAART start, lower pre-HAART CD4+ nadir, higher pre-HAART VL, and clinical AIDS before HAART (P < 0.05).

Conclusions

Small but positive long-term increases in CD4+ count in virally suppressed patients were observed. CD4+ response to HAART is influenced by multiple factors including duration of preceding HIV infection, and optimized if treatment is started with virally suppressive therapy as early as possible.

HIV-1 matrix protein p17: a candidate antigen for therapeutic vaccines against AIDS

The success in the development of anti-retroviral therapies (HAART) that contain human immunodeficiency virus type 1 (HIV-1) infection is challenged by the cost of this lifelong therapy and by its toxicity. Immune-based therapeutic strategies that boost the immune response against HIV-1 proteins or protein subunits have been recently proposed to control virus replication in order to provide protection from disease development, reduce virus transmission, and help limit the use of anti-retroviral treatments. HIV-1 matrix protein p17 is a structural protein that is critically involved in most stages of the life cycle of the retrovirus. Besides its well established role in the virus life cycle, increasing evidence suggests that p17 may also be active extracellularly in deregulating biological activities of many different immune cells that are directly or indirectly involved in AIDS pathogenesis. Thus, p17 might represent a promising target for developing a therapeutic vaccine as a contribution to combating AIDS. In this article we review the biological characteristics of HIV-1 matrix protein p17 and we describe why a synthetic peptide representative of the p17 functional epitope may work as a vaccine molecule capable of inducing anti-p17 neutralizing response against p17 derived from divergent HIV-1 strains.

Immune mechanisms of HIV control

HIV-1 can be contained by the immune system, as demonstrated by the existence of rare individuals who spontaneously control HIV-1 replication in the absence of antiretroviral therapy. Emerging evidence points to the importance of a very active cellular immune response in mediating HIV-1 control. The rapid induction of interferon-dependent HIV restriction factors, the presence of protective MHC class I alleles, and the development of a high avidity T-cell response may all cooperate in limiting HIV replication at an early stage. This review will focus on recent advances in understanding the immune mechanisms of HIV control, and on the lessons that may be drawn for the development of candidate HIV vaccines.