CD4/CD8 ratio and CD8 counts predict CD4 response in HIV-1-infected drug naive and in patients on cART

Asymptotic Properties for Cumulative Probability Models for Continuous Outcomes

Regression models for continuous outcomes frequently require a transformation of the outcome, which is often specified a priori or estimated from a parametric family. Cumulative probability models (CPMs) nonparametrically estimate the transformation by treating the continuous outcome as if it is ordered categorically. They thus represent a flexible analysis approach for continuous outcomes. However, it is difficult to establish asymptotic properties for CPMs due to the potentially unbounded range of the transformation. Here we show asymptotic properties for CPMs when applied to slightly modified data where bounds, one lower and one upper, are chosen and the outcomes outside the bounds are set as two ordinal categories. We prove the uniform consistency of the estimated regression coefficients and of the estimated transformation function between the bounds. We also describe their joint asymptotic distribution, and show that the estimated regression coefficients attain the semiparametric efficiency bound. We show with simulations that results from this approach and those from using the CPM on the original data are very similar when a small fraction of the data are modified. We reanalyze a dataset of HIV-positive patients with CPMs to illustrate and compare the approaches.

Analyzing clustered continuous response variables with ordinal regression models

Continuous response data are regularly transformed to meet regression modeling assumptions. However, approaches taken to identify the appropriate transformation can be ad hoc and can increase model uncertainty. Further, the resulting transformations often vary across studies leading to difficulties with synthesizing and interpreting results. When a continuous response variable is measured repeatedly within individuals or when continuous responses arise from clusters, analyses have the additional challenge caused by within-individual or within-cluster correlations. We extend a widely used ordinal regression model, the cumulative probability model (CPM), to fit clustered, continuous response data using generalized estimating equations for ordinal responses. With the proposed approach, estimates of marginal model parameters, cumulative distribution functions , expectations, and quantiles conditional on covariates can be obtained without pretransformation of the response data. While computational challenges arise with large numbers of distinct values of the continuous response variable, we propose feasible and computationally efficient approaches to fit CPMs under commonly used working correlation structures. We study finite sample operating characteristics of the estimators via simulation and illustrate their implementation with two data examples. One studies predictors of CD4:CD8 ratios in a cohort living with HIV, and the other investigates the association of a single nucleotide polymorphism and lung function decline in a cohort with early chronic obstructive pulmonary disease.

Decreased CD73+ Double-Negative T Cells and Elevated Level of Soluble CD73 Correlated With and Predicted Poor Immune Reconstitution in HIV-Infected Patients After Antiretroviral Therapy

Although extensive use of antiretroviral therapy (ART) has made great progress in controlling HIV replication and improving CD4+ T cell recovery, the immune reconstitution remained insufficient in some patients, who were defined as poor immunological responders (PIRs). These PIRs were at a high risk of AIDS-related and non-AIDS complications, resulting in higher morbidity and mortality rate. Thus, it is a major challenge and urgently needed to distinguish PIRs early and improve their immune function in time. Immune activation is a key factor that leads to impaired immune reconstitution in people living with HIV (PLWH) who are receiving effective ART. Double negative T cells (DNT) were reported to associate with the control of immune activation during HIV infection. However, the precise mechanisms by which DNT cells exerted their suppressive capacity during HIV infection remained puzzled. CD73, both a soluble and a membrane-bound form, display immunosuppressive effects through producing adenosine (ADO). Thus, whether DNT cells expressed CD73 and mediated immune suppression through CD73-ADO pathway needs to be investigated. Here, we found a significant downregulation of CD73 expression on DNT cells in treatment-naïve PLWH (TNs) compared to healthy controls, accompanied with increased concentration of sCD73 in plasma. Both the frequency of CD73+ DNT cells and the level of plasma sCD73 recovered after ART treatment. However, PIRs showed decreased percentage of CD73+ DNT cells compared to immunological responders (IRs). The frequency of CD73+ DNT cells was positively correlated with CD4+ T cell count and CD4/CD8 ratio, and negatively correlated with immune activation in PLWH. The level of sCD73 also showed a negative correlation to CD4+ T cell count and CD4/CD8 ratio. More importantly, in the present cohort, a higher level of sCD73 at the time of initiating ART could predict poor immune reconstitution in PLWH after long-term ART. Our findings highlighted the importance of CD73+ DNT cells and sCD73 in the disease progression and immune reconstitution of PLWH, and provided evidences for sCD73 as a potential biomarker of predicting immune recovery.

Atypical Resting-State Functional Connectivity Dynamics Correlate With Early Cognitive Dysfunction in HIV Infection

Purpose: Previous studies have shown that HIV affects striato-cortical regions, leading to persisting cognitive impairment in 30-70% of the infected individuals despite combination antiretroviral therapy. This study aimed to investigate brain functional dynamics whose deficits might link to early cognitive decline or immunologic deterioration. Methods: We applied sliding windows and K-means clustering to fMRI data (HIV patients with asymptomatic neurocognitive impairment and controls) to construct dynamic resting-state functional connectivity (RSFC) maps and identify states of their reoccurrences. The average and variability of dynamic RSFC, and the dwelling time and state transitioning of each state were evaluated. Results: HIV patients demonstrated greater variability in RSFC between the left pallidum and regions of right pre-central and post-central gyri, and between the right supramarginal gyrus and regions of the right putamen and left pallidum. Greater variability was also found in the frontal RSFC of pars orbitalis of the left inferior frontal gyrus and right superior frontal gyrus (medial). While deficits in learning and memory recall of HIV patients related to greater striato-sensorimotor variability, deficits in attention and working memory were associated with greater frontal variability. Greater striato-parietal variability presented a strong link with immunologic function (CD4+/CD8+ ratio). Furthermore, HIV-infected patients exhibited longer time and reduced transitioning in states typified by weaker connectivity in specific networks. CD4+T-cell counts of the HIV-patients were related to reduced state transitioning. Conclusion: Our findings suggest that HIV alters brain functional connectivity dynamics, which may underlie early cognitive impairment. These findings provide novel insights into our understanding of HIV pathology, complementing the existing knowledge.

Immune recovery in HIV-1 infected patients with sustained viral suppression under long-term antiretroviral therapy in Ethiopia

BACKGROUND

There is very little data on long-term immune recovery responses in patients on suppressive antiretroviral therapy (ART) in the setting of sub-Saharan Africa (SSA). Thus, we sought to determine CD4+ T-cell, CD8+ T-cell and CD4/CD8 ratio responses in a cohort of HIV infected individuals on sustained suppressive ART followed up for more than a decade.

METHODS

The cohort comprised adult patients who started ART between 2001 and 2007 and followed for up to 14 years. Trends in median CD4+ T-cells, CD8+ T-cells and CD4/CD8 ratio were reviewed retrospectively. Poisson regression models were used to identify factors associated with achieving normalized T-cell biomarkers. Kaplan-Meier curves were used to estimate the probability of attaining normalized counts while on suppressive ART.

RESULTS

A total of 227 patients with a median duration of follow-up on ART of 12 (IQR: 10.5-13.0) years were included. CD4 cell count increased from baseline median of 138 cells (IQR: 70-202) to 555 cells (IQR: 417-830). CD4 cell increased continuously up until 5 years, after which it plateaued up until 14 years of follow up. Only 69.6% normalized their CD4 cell count within a median of 6.5 (IQR: 3.0-10.5) years. In addition, only 15.9% of the cohort were able to achieve the median reference CD4+ T-cell threshold count in Ethiopians (≈760 cells/μL). CD8+ T-cell counts increased initially until year 1, after which continuous decrease was ascertained. CD4/CD8 ratio trend revealed continuous increase throughout the course of ART, and increased from a median baseline of 0.14 (IQR: 0.09-0.22) to a median of 0.70 (IQR: 0.42-0.95). However, only 12.3% normalized their ratio (≥ 1.0) after a median of 11.5 years. In addition, only 8.8% of the cohort were able to achieve the median reference ratio of healthy Ethiopians.

CONCLUSION

Determination of both CD4+ and CD8+ T-cells, along with CD4/CD8 ratio is highly relevant in long-term follow-up of patients to assess immune recovery. Monitoring ratio levels may serve as a better biomarker risk for disease progression among patients on long-term ART. In addition, the findings emphasize the relevance of initiation of ART at the early stage of HIV-1 infection.

Predicción temporal de CD4+ en 80 pacientes con manejo antirretroviral a partir de valores de leucocitos

Objetivo: establecer una metodología predictiva de aplicación clínica de recuentos de CD4+ en rangos de interés clínico a partir del recuento absoluto de leucocitos.Metodología: a partir de los valores secuenciales de leucocitos y linfocitos CD4+ de 9 pacientes, se observaron patrones matemáticos que posteriormente fueronaplicados en un estudio ciego con 71 casos para confirmar su capacidad predictiva, midiendo porcentajes de especificidad y sensibilidad. Resultados: se determinaron cinco patrones matemáticos que predicen en el 99% de los casos los distintos recuentos de CD4+ a partir de recuentos de leucocitos con valores de especificidad y sensibilidad del 99%. Conclusiones: los patrones matemáticos encontrados entre recuento de leucocitos y CD4+ sugieren que este fenómeno prácticamente es determinista.

CD4+:CD8+ T-cell ratio changes in people with HIV receiving antiretroviral treatment

BACKGROUND

Cofactors associated with persistently abnormal CD4⁺:CD8⁺ T-cell ratio in people with HIV (PWH) on antiretroviral treatment (ART) might change over time as the population of people with HIV ages or as new ART drugs become available. The main objective of our study was to determine the long-term associations of baseline factors, including the CD4⁺ T-cell count and ratio, with ratio normalization (≥1). In addition to this, we explored whether the ratio remained associated with the risk of both AIDS and non-AIDS events among individuals on suppressive ART.

METHODS

Clinic-based study in a tertiary, university hospital in Madrid. People with HIV starting a first-line ART regimen (January 2006-June 2017) were included in a prospective national multicentre cohort (CoRIS). People with controlled HIV-infection within the first year of ART initiation and complete CD4⁺ and CD8⁺ T-cell records were selected. Cox proportional hazard (PH) regression models were used to estimate the cumulative incidence of ratio normalization and to examine associations with socio-demographic and clinical variables. To investigate factors independently associated with the development of AIDS and non-AIDS events we used a time updated Poisson regression model.

RESULTS

The study included 557 subjects. During follow-up (median 5.24 years), 44% of participants achieved a ratio of 1 within a median of 1.49 years. In a multivariate PH model, pre-ART factors negatively associated with ratio normalization were the pre-ART CD4⁺:CD8⁺ T-cell ratio and mode of HIV acquisition. For the secondary analysis, 1.3 events/100 person years of follow-up were observed. After adjustment, older age, HIV RNA >200 copies/ml and CD4⁺:CD8⁺ T-cell ratios over follow-up, remained significantly associated with the development of AIDS and non-AIDS events. In contrast, pre-ART ratio was not associated with the risk of AIDS and non-AIDS events.

CONCLUSIONS

In summary, our study showed that higher pre-ART CD4⁺:CD8⁺ T-cell ratio is associated with rates of ratio normalization ≥1. In addition, the risk of AIDS and non-AIDS events seems to be predicted by the time updated CD4⁺:CD8⁺ T-cell ratio not by the pre-ART CD4⁺:CD8⁺ T-cell ratio. Therefore, CD4⁺:CD8⁺ T-cell ratio should be considered as a dynamic marker for translation into clinical practice.

Immune profile at HIV infection diagnosis: Evolution in the French Alps area over the last 20 years

OBJECTIVES

Health of HIV-infected people relies on early antiretroviral therapy, i.e. early diagnosis. We aimed to determine whether the characteristics at HIV diagnosis in two French medical centres changed over the last 20 years.

PATIENTS AND METHODS

All individuals diagnosed with HIV infection in Grenoble University Hospital (N=814) and Annecy Hospital (N=246) between 1997 and 2015 were included. We collected age, country of birth, mode of transmission, CD4T cell count, CD4/CD8 ratio, and HIV viral load.

RESULTS

Among the 1060 patients (mean age 37.4±11 years, 70.2% of men), 42.5% were men having sex with men (MSM); 65.2% were born in France, and 24.4% were born in Africa. Mean CD4T cell count at diagnosis was 396±288/mm³ and was stable over the study period when considering all patients; when considering the MSM group, a significant increase over time was observed, with a mean increase of 7.3 CD4/mm³ per year (P<0.001). A higher CD4 count at diagnosis was observed after 2005 (400±289 vs 468±271/mm³, P=0.005). The proportion of MSM patients with a CD4 count<200/mm³ at diagnosis was lower after 2005 (14.7% after 2005 and 25.6% before, P=0.028) This was not observed in heterosexual patients (born in Africa or not).

CONCLUSION

In the MSM population, CD4 count at diagnosis is higher after 2005, suggesting that screening campaigns have become more efficient. This was not observed in other populations, who should be better targeted in future strategies.

Acute HIV Infection and CD4/CD8 Ratio Normalization After Antiretroviral Therapy Initiation

BACKGROUND

We estimated the effect of initiating virologically suppressive antiretroviral therapy (ART) during acute HIV infection versus chronic HIV infection (AHI vs. CHI) on CD4/CD8 ratio normalization.

SETTING

A prospective clinical cohort study.

METHODS

We included patients initiating ART with AHI and CHI between 2000 and 2015 and compared time from ART initiation to the first normal CD4/CD8 ratio (defined as CD4/CD8 ≥1) using Kaplan-Meier curves and multivariable Cox proportional hazards models. Patient time was censored at virologic failure, lost to follow-up, or death. We also characterized CD4, CD8, and CD4/CD8 trajectories over the first 3 years of ART.

RESULTS

The 1198 patients were 27% female and 60% African American, with a median age of 37 years (interquartile range 28-47) at ART initiation. The 83 AHI patients were more likely male, younger, and of white race, than CHI patients. After 2 years of suppressive ART, 70% of AHI patients achieved a normal CD4/CD8 ratio, compared to 6%-38% of CHI patients, with greater likelihood of normalization at higher baseline CD4 counts. Time to normalization was shortest among AHI patients, followed by CHI patients with higher baseline CD4. The adjusted hazard ratio for time to normalization for AHI patients compared to CHI patients with baseline CD4 >350 was 4.33 (95% CI: 3.16 to 5.93). Higher baseline CD4/CD8 ratio was also associated with time to normalization (adjusted hazard ratio 1.54; 1.46, 1.63, per 0.1 increase in ratio).

CONCLUSIONS

Initiating ART during AHI at higher baseline CD4 cell counts and CD4/CD8 ratios was associated with shorter time to CD4/CD8 ratio normalization.

CD4/CD8 Ratio and CD4 Nadir Predict Mortality Following Noncommunicable Disease Diagnosis in Adults Living with HIV

Incidence of noncommunicable diseases (NCDs), including cardiovascular disease (CVD), cirrhosis, and non-AIDS-defining cancers (NADCs), have been associated with HIV viremia, CD4 cell counts, and CD4/CD8 ratio in persons living with HIV (PLWH). This study examined the importance of these markers to mortality risk following NCD diagnosis. We examined factors associated with mortality following incident CVD, cirrhosis, or NADCs in a clinical cohort of PLWH between 1998 and 2015. We calculated Kaplan-Meier estimates and used multivariable Cox proportional hazard models. We included 341 patients with NCDs (CVD = 169, cancer = 103, and cirrhosis = 67), of whom 129 died. Median age at NCD diagnosis was 49 years and median proportion of time before NCD with virologic suppression was 64%. Median survival after CVD was longer than for cancer or cirrhosis (11.6 years vs. 4.8 and 3.4 years, respectively; log rank test p < .001). In multivariable Cox proportional hazard models, higher CD4/CD8 ratio preceding NCD (adjusted hazard ratio [aHR] per 0.1 increase = 0.92 [95% confidence interval 0.85-0.99]) and higher CD4 nadir (aHR per 100 cells/μL = 0.84 [0.72-0.97]) were associated with decreased mortality risk. Neither CD4 cell count before NCD nor HIV viremia was statistically associated with mortality in adjusted models. When restricted to 116 patients with virologic suppression for ≥80% of time before NCD, only CD4 nadir was associated with mortality risk. Low CD4/CD8 ratio and CD4 nadir were associated with increased mortality risk after NCD, suggesting that prior immunosuppression or ongoing immune imbalance remain important for outcomes following serious NCDs.

Prediction of CD4+ Cells Counts in HIV/AIDS Patients based on Sets and Probability Theories

BACKGROUND

Previous studies have developed methodologies for predicting the number of CD4+ cells from the total leukocyte and lymphocytes count based on mathematical methodologies, obtaining percentages of effectiveness prediction higher than 90% with a value of less than 5000 leukocytes.

OBJECTIVE

To improve the methodology probabilities prediction in 5000-9000 leukocytes ranges.

METHOD

from sets A, B, C and D defined in a previous study, and based on CD4+ prediction established on the total number of leukocytes and lymphocytes, induction was performed using data from 10 patients with HIV, redefining the sets A and C that describe the lymphocytes behavior relative to leukocytes. Subsequently, we evaluated with previous research prediction probabilities parameters from a sample of 100 patients, calculating the belonging probability to each sample and organized in predetermined ranges leukocytes, of each of the sets defined, their unions and intersections. Then the same procedure was performed with the new sets and the probability values obtained with the refined method were compared with respect to previously defined, by measures of sensitivity (SENS) and Negative Predictive Value (NPV) for each range.

RESULTS

probabilities with values greater than 0.83 were found in five of the nine ranges inside the new sets. The probability for the set A∪C increased from 0.06 to 0.18 which means increases between 0.06 and 0.09 for the intersection (A∪C) ∩ (B∪D), making evident the prediction improvement with new sets defined.

CONCLUSION

The results show that the new defined sets achieved a higher percentage of effectiveness to predict the CD4+ value cells, which represents a useful tool that can be proposed as a substitute for clinical values obtained by the flow cytometry.

Prognostic factors of a lower CD4/CD8 ratio in long term viral suppression HIV infected children

BACKGROUND

Combination antiretroviral therapy (cART) is associated with marked immune reconstitution. Although a long term viral suppression is achievable, not all children however, attain complete immunological recovery due to persistent immune activation. We use CD4/CD8 ratio like a marker of immune reconstitution.

METHODS

Perinatal HIV-infected children who underwent a first-line cART, achieved viral suppression in the first year and maintained it for more than 5 years, with no viral rebound were included. Logistic models were applied to estimate the prognostic factors, clinical characteristics at cART start, of a lower CD4/CD8 ratio at the last visit.

RESULTS

146 HIV-infected children were included: 77% Caucasian, 45% male and 28% CDC C. Median age at cART initiation was 2.3 years (IQR: 0.5-6.2). 42 (30%) children received mono-dual therapy previously to cART. Time of undetectable viral load was 9.5 years (IQR: 7.8, 12.5). 33% of the children not achieved CD4/CD8 ratio >1. Univariate analysis showed an association between CD4/CD8 <1 with lower CD4 nadir and baseline CD4; older age at diagnosis and at cART initiation; and a previous exposure to mono-dual therapy. Multivariate analysis also revealed relationship between CD4/CD8 <1 and lower CD4 nadir (OR: 1.002, CI 95% 1.000-1.004) as well as previous exposure to mono-dual therapy (OR: 0.16, CI 95% 0.003-0.720).

CONCLUSIONS

CD4/CD8 >1 was not achieved in 33% of the children. Lower CD4 nadir and previous exposure to suboptimal therapy, before initiating cART, are factors showing independently association with a worse immune recovery (CD4/CD8 < 1).

CD4/CD8 Ratio as a Predictor for the Occurrence of Metabolic Syndrome in HIV / AIDS Patients During 6 Months of cART Therapy

Background

HIV infection is characterized by progressive depletion of CD4⁺ T cells due to their reduced synthesis and increased destruction followed by marked activation and expansion of CD8⁺ T lymphocytes. CD4/CD8 ratio was traditionally described as a marker of immune system ageing in the general population, but it increasingly appears as a marker of different outcomes in the HIV-infected population. The main objective of this study is to examine the power of CD4/CD8 ratio in predicting the occurrence of metabolic syndrome (MetS) in HIV-positive patients receiving cART therapy.

Methods

80 HIV/AIDS subjects were included in a retrospective case-control study. Flow cytometry was used to determine the percentage of CD4⁺ and CD8⁺ cells in peripheral blood of these patients. The values of biochemical parameters (triglycerides, HDL, blood sugar, blood counts), immunological parameters (CD4/CD8, PCR), anthropometric measurements and type of cART therapy were evaluated in this study.

Results

After six months of cART therapy 19 (23.8%) subjects had all the elements necessary for making the diagnosis of MetS. Using multivariate analysis CD4/CD8 ratio was statistically significant (p < 0.05) and had the largest effect on development of MetS (Wald = 9.01; OR = 0.45), followed by cART (Wald = 7.87; OR = 0.10) and triglycerides (Wald = 5.27; OR = 1.7). On the other hand, body weight and waist circumference showed no statistically significant effect on the development of MetS after six months of cART, p > 0.05.

Conclusions

CD4/CD8 ratio proved to be a significant marker for prediction of metabolic syndrome in HIV/AIDS patients.

Immune response to a Tdap booster in vertically HIV-infected adolescents

BACKGROUND

Pertussis cases have increased worldwide and knowledge on immune response and cytokine profile after Tdap vaccine in immunodeficient adolescents is scarce.

OBJECTIVE

To evaluate the immune response after Tdap in HIV-infected (HIV) and in healthy adolescents (CONTROL).

METHODOLOGY

Thirty HIV adolescents with CD4 cell counts >200 and 30 CONTROLs were immunized with Tdap, after a prior whole-cell DTP vaccine primary scheme. Blood samples were collected immediately before and after vaccine. Lymphocyte immunophenotyping was performed by flow cytometry; tetanus, diphtheria and pertussis toxin antibodies were assessed by ELISA; whole blood was stimulated with tetanus toxoid and Bordetella pertussis and supernatants were assessed for cytokines by xMAP.

RESULTS

Mean age of HIV and CONTROL groups were 17.9 e 17.1 years, respectively. Pain at injection site was more intense in CONTROL group. HIV group had similar increase in tetanus antibodies at 28 days (geometric mean concentration, GMC, 15.6; 95% CI, 7.52-32.4) than CONTROL group (GMC, 23.1; 95% CI, 15.0-35.5), but lower diphtheria antibodies at 28 days (GMC, 2.3; 95% CI, 0.88-6.19) than CONTROL group (GMC, 16.4; 95% CI, 10.3-26.2); for pertussis, the percentage of individuals who seroconverted was lower in HIV than CONTROL group (HIV, 62.1% versus CONTROL, 100%; p = .002). Both groups built a cellular immune response to tetanus, with a Th2 (IL-4, IL-5 and IL-13) and Th1 (IFN-γ) response, with lower cytokine levels in HIV than in CONTROL group. Especially for pertussis, cellular and humoral responses were less intense in HIV adolescents, with a lower Th1 and Th17 profile and higher IL-10 levels. HIV-infected adolescents on viral suppression showed an enhanced immune response to all the three vaccine antigens, although still at lower levels if compared to CONTROL group.

CONCLUSIONS

Both groups tolerated well and built an immune response after Tdap. However, HIV-infected adolescents would probably benefit from more frequent booster doses.

Antiretroviral Drugs for Treatment and Prevention of HIV Infection in Adults: 2018 Recommendations of the International Antiviral Society-USA Panel

IMPORTANCE

Antiretroviral therapy (ART) is the cornerstone of prevention and management of HIV infection.

OBJECTIVE

To evaluate new data and treatments and incorporate this information into updated recommendations for initiating therapy, monitoring individuals starting therapy, changing regimens, and preventing HIV infection for individuals at risk.

EVIDENCE REVIEW

New evidence collected since the International Antiviral Society-USA 2016 recommendations via monthly PubMed and EMBASE literature searches up to April 2018; data presented at peer-reviewed scientific conferences. A volunteer panel of experts in HIV research and patient care considered these data and updated previous recommendations.

FINDINGS

ART is recommended for virtually all HIV-infected individuals, as soon as possible after HIV diagnosis. Immediate initiation (eg, rapid start), if clinically appropriate, requires adequate staffing, specialized services, and careful selection of medical therapy. An integrase strand transfer inhibitor (InSTI) plus 2 nucleoside reverse transcriptase inhibitors (NRTIs) is generally recommended for initial therapy, with unique patient circumstances (eg, concomitant diseases and conditions, potential for pregnancy, cost) guiding the treatment choice. CD4 cell count, HIV RNA level, genotype, and other laboratory tests for general health and co-infections are recommended at specified points before and during ART. If a regimen switch is indicated, treatment history, tolerability, adherence, and drug resistance history should first be assessed; 2 or 3 active drugs are recommended for a new regimen. HIV testing is recommended at least once for anyone who has ever been sexually active and more often for individuals at ongoing risk for infection. Preexposure prophylaxis with tenofovir disoproxil fumarate/emtricitabine and appropriate monitoring is recommended for individuals at risk for HIV.

CONCLUSIONS AND RELEVANCE

Advances in HIV prevention and treatment with antiretroviral drugs continue to improve clinical management and outcomes for individuals at risk for and living with HIV.

Residual Immune Activation and Latency

The introduction of combination antiretroviral therapy (cART) in the 1990s has dramatically changed the course of HIV infection, decreasing the risk for both AIDS- and non-AIDS-related events. Cancers, cardiovascular disease (CVD), liver and kidney disease, neurological disorders and frailty have become of great importance lately in the clinical management as they represent the principal cause of death in people living with HIV who receive cART (Kirk et al. in Clin Infect Dis 45(1):103-10, 2007; Strategies for Management of Antiretroviral Therapy Study et al. N Engl J Med 355(22):2283-2296, 2006; Ances et al. J Infect Dis 201(3):336-340, 2010; Desquilbet et al. J Gerontol A Biol Sci Med Sci 62(11):1279-1286, 2007; Lifson et al. HIV Clin Trials 9(3):177-185, 2008). Despite the undeniable achievements of cART, we are now faced with its limitations: a considerable proportion of individuals, referred as to immunological non-responders, fails to reconstitute the immune system despite optimal treatment and viral suppression (Kelley et al. Clin Infect Dis 48(6):787-794, 2009; Robbins et al. Clin Infect Dis 48(3):350-361, 2009) and remains at high risk for opportunistic infections and non-AIDS-related events (Strategies for Management of Antiretroviral Therapy Study et al. N Engl J Med 355(22):2283-2296, 2006). Moreover, the generalized state of immune activation and inflammation, linked to serious non-AIDS events, persists despite successful HIV suppression with cART. Finally, the current strategies have so far failed to eradicate the virus, and inflammation appears a driving force in viral persistence. In the light of all this, it is of fundamental importance to investigate the pathophysiological processes that link incomplete immune recovery, immune activation and HIV persistence to design targeted therapies that could impact on the three.

Effects of Amprenavir on HIV-1 Maturation, Production and Infectivity Following Drug Withdrawal in Chronically-Infected Monocytes/Macrophages

A paucity of information is available on the activity of protease inhibitors (PI) in chronically-infected monocyte-derived macrophages (MDM) and on the kinetics of viral-rebound after PI removal in vitro. To fill this gap, the activity of different concentrations of amprenavir (AMP) was evaluated in chronically-infected MDM by measuring p24-production every day up to 12 days after drug administration and up to seven days after drug removal. Clinically-relevant concentrations of AMP (4 and 20 μM) drastically decreased p24 amount released from chronically-infected MDM from Day 2 up to Day 12 after drug administration. The kinetics of viral-rebound after AMP-removal (4 and 20 μM) showed that, despite an initial increase, p24-production over time never reached the level observed for untreated-MDM, suggesting a persistent intracellular drug activity. In line with this, after AMP-removal, human immunodeficiency virus 1 (HIV-1) infectivity and intracellular the p24/p55 ratio (reflecting virion-maturation) were remarkably lower than observed for untreated MDM. Overall, AMP shows high efficacy in blocking HIV-1 replication in chronically-infected MDM, persisting even after drug-removal. This highlights the role of protease inhibitors in preventing the establishment of this important HIV-1 reservoir, thus reducing viral-dissemination in different anatomical compartments.