Genetic analyses reveal structured HIV-1 populations in serially sampled T lymphocytes of patients receiving HAART

HIV-1 infection and compartmentalization in diverse leukocyte targets significantly contribute to viral persistence during suppressive highly active antiretroviral therapy (HAART). Longitudinal analyses were performed on envelope sequences of HIV-1 populations from plasma, CD4+ and CD8+ T lymphocytes in 14 patients receiving HAART and 1 therapy-naive individual. Phylogenetic reconstructions and analysis of molecular variance revealed that HIV-1 populations in CD4+ and CD8+ T cells remained compartmentalized over time in most individuals. Analyses of viral genetic variation demonstrated that, despite compartmentalization remaining over time, viral subpopulations tended not to persist and evolve but instead broke down and became reconstituted by new founder viruses. Due to the profound impact of HAART on viral evolution, it was difficult to discern whether these dynamics were ongoing during treatment or predominantly established prior to the commencement of therapy. The genetic structure and viral founder effects observed in serially sampled T lymphocyte populations supported a scenario of metapopulation dynamics in the tissue(s) where different leukocytes become infected, a factor likely to contribute to the highly variable way that drug resistance evolves in different individuals during HAART.     

艾滋病HAART治疗免疫重建炎性综合征的免疫机制初步研究

目的 为探讨我国艾滋病病人(AIDS)启动高效抗反转录病毒治疗(HAART)后,发生免疫重建炎性综合征(IRIS)的免疫学发病机制,在前瞻性研究队列中对启动HAART的AIDS病人部分淋巴细胞亚群、调节性T细胞和部分Th1和Th2细胞因子等进行追踪分析.方法 将接受HAART初始治疗的238例AIDS病人建立前瞻性研究队列,分为在24周内发生IRIS的47例病人(IRIS组)和未发生IRIS的191例病人(非IRIS组).在HAART的0周、12周和24周采集两组血标本,对47例IRIS病例及随机选择的50例非IRIS病例进行免疫机制的研究分析,检测HIV病毒载量和CD4+细胞计数;使用流式细胞术检测部分淋巴细胞亚群和调节性T细胞(CD4+CD25+Foxp3+).在HAART的0周、4周、12周、24周及发生IRIS时分别采集全部238例患者的血标本,使用ELISA法测定血浆细胞因子IL-2、IFN-γ、IL-4、IL-10以及IL-7水平.结果 两组感染者的CD4+、CD8+纯真细胞和记忆细胞比例在0周、12周、24周及发生IRIS时比较差异均无统计学意义,但CD4+记忆细胞和CD8+记忆细胞比例在启动HAART后均明显上升.两组感染者CD4+CD38+活化细胞和CD8+CD38+活化细胞比例在基线时均较正常值明显升高,治疗后均有下降趋势.在0周、12周、24周及发生IRIS时CD4+CD25+Foxp3+调节性T细胞在IRIS组中均较非IRIS组要低.两组IL-2及IFN-γ在HAART后均呈上升趋势,且IRIS组在4周及发生IRIS时更明显高于非IRIS组;两组IL-4及IL-10在HAART后均呈下降趋势,IRIS组中IL-10在4周及发生IRIS时更明显低于非IRIS组.IL-7在两组中基线时均较正常值升高,并随HAART进程逐渐降低,其中IRIS组在各随访点IL-7均要高于非IRIS组.结论 接受HAART治疗者早期即出现记忆T细胞快速上升,在IRIS炎症反应中可能起重要作用.IL-2、IL-10和IFN-γ在发生IRIS时的水平差别,提示IRIS的发生与炎性细胞因子大量增加,炎性抑制因子相对不足有一定关系.IL-7也可能参与到IRIS的发病机制中.

Abstract：

Objective To investigate the immunological pathogenesis of immune reconstitution inflammatory syndrome (IRIS) during highly active antiretroviral therapy( HAART), in this prospective cohort study we analyzed the lymphocyte subsets, lymphocyte activation, changes in regulatory T cells, and levels of Th1 and Th2 cytokines in both IRIS and non-IRIS groups. Methods Two hundred and thirty-eight AIDS patients received HAART and participated prospective research cohort for 24 weeks follow-up. Forty-seven IRIS cases and 191 non-IRIS cases were enrolled in the IRIS group or non-IRIS group respectively. Blood samples were collected in both groups at pre- and post-HAART 12 weeks, 24 weeks. Using flow cytometer to detect the immunophenotypes of lymphocyte subsets (CD4 + CD45RA+ CD62L+, CD8+ CD45RA+ CD62L+naive T cells; CD4+ CD45RO+, CD8+ CD45RO+ memory T cells), activated T lymphocytes (CD4+CD38 +, CD8 + CD38 + cells), and regulatory T cell ( CD4 + CD25 + Foxp3 + ). Blood samples collected at pre-and post-HAART4 weeks, 12 weeks, 24 weeks and used ELISA to detect IL-2, IFN-γ, IL-4, IL-10and IL-7 cytokine serum levels. Results The percentages of CD4 + and CD8 + naive T cells and mlemory T cells exhibited no significant differences at the baseline, 12 weeks, 24 weeks of HAART initiation between both groups, but CD4 + and CD8 + memory T cells were demonstrated a trend towards to increase while compared to baseline during HAART. The percentages of CD4 + and CD8 + activated T cells are significantly higher at the baseline while compared to normal control and demonstrated a downward trend, but between both groups showed no significant difference. The percentages of CD4 + regulatory T cell was lower in IRIS group than non-IRIS group at the baseline, 12 weeks, 24 weeks and the onset of IRIS. Th1 cytokines, IL-2 and IFN-γshowed an upward trend during HAART at the levels of IRIS group had significantly increased at 4 weeks and the onset of IRIS. Th2 cytokines, IL-4 and IL-10 showed a downward trend during HAART,and the levels of IL-10 in IRIS group had significantly decreased at 4 weeks and the onset of IRIS. IL-7 was higher than normal control at the baseline in two groups and showed a downward trend during HAART. The level of IL-7 was higher than non-IRIS group at all follow-up points. Conclusion Memory T cells appear rapid increase in the early stage of HAART and may play a significant role in the inflammatory response of IRIS. CD4 + and CD8 + naive T cells, memory T cells and activated T cells showed no significant difference between IRIS and non-IRIS group within 24 weeks after HAART started. There was a significant reduction in the frequency of regulatory T cells in IRIS group without obvious upward trend during HAART, suggesting that the immune suppression function of regulatory T cells in IRIS was impaired. IL-2 and IFN-γ significantly increased while IL-10 significantly decreased at 4 weeks post-HAART initiation and onset of IRIS in IRISgroup than non-IRIS group, suggested that IRIS was related to cytokines environment disorder. That is, a significant increase in inflammatory cytokines, while the relative lack of non-inflammatory cytokines. The level of IL-7 decreased gradually after HAART started, and it was higher in IRIS group when compared to non-IRIS group in the first 24 weeks after HAART started. Also IL-7 may play a role in the pathogenesis of IRIS.     

Immune function and phenotype before and after highly active antiretroviral therapy.

Immune functions represented by equal CD4 counts before and after highly active antiretroviral therapy (i.e., pre- and post-HAART) in the same HIV-infected patients, were examined. Twelve HIV-infected patients were included. Patients had equal CD4 counts pre- and post-HAART and were studied on average 30 months pre-HAART and 17 months post-HAART. Post-HAART, CD8+ T cells expressed greater amounts of CD28 (p < .02), smaller amounts of CD38 (p < .02), and a reduced proportion of CD4+CD28+ T cells expressed CD38+ (p < .01). Proliferation increased (p < 10) in lymphocyte cell cultures stimulated with pokeweed mitogens or Candida, and was correlated to expression of CD28 on T cells (p < .02). The proportion of CD3-CD16-CD56+ natural killer (NK) cells increased (p < .05) and CD3-CD16+CD56- NK cells declined (p < .01). Production of interferon-gamma increased (p < .10). The number of naive and memory T cells, the non-major histocompatibility complex (non-MHC)-restricted and HIV-specific MHC-restricted cytotoxicity and the production of macrophage inflammatory protein-1gamma were unchanged. The finding of increased expression of CD28, correlating to increased proliferation capacity, and diminished expression of CD38 on T cells, indicates that following long-term HAART, repopulation occurs with less activated cells with increased proliferative capacity. This finding may be of clinical importance in considering risk and vulnerability for progression of opportunistic infections post-HAART.     

T-cell receptor excisional circles,telomere length,proliferation and apoptosis in peripheral blood mononuclear cells of human immunodeficiency virus-infected individuals after 18 months of treatment induced viral suppression

This study evaluated the effect of highly active antiretroviral therapy (HAART)-induced viral suppression on T-cell receptor excisional circles (TRECs), telomere length, proliferative responses and spontaneous as well as phytohaemagglutinin (PHA)-stimulated lymphocyte apoptosis in 27 human immunodeficiency virus (HIV)-infected individuals followed for 18 months during HAART. Our results show that HAART significantly increased the level of TRECs in CD4+ cells (P = 0.003) after 18 months of almost continuously suppressed HIV-RNA levels. Lymphocyte proliferative responses and apoptosis levels in patients were significantly lower and significantly higher, respectively, compared with healthy controls. The proliferative response and apoptosis levels did not change during follow up. Changes in telomere length were observed in CD4+ and in CD8+ T cells. The study demonstrated that HAART induces normal TREC levels in the CD4+ T-cell pool. However, the other perturbed functions in T cells indicate that immune reconstitution is incomplete and may need longer viral suppression.     

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.     

Apparent elimination of EIAV ancestral species in a long-term inapparent carrier

Equine infectious anemia virus (EIAV) envelope variation produces newly dominant quasispecies with each sequential disease cycle; new populations arise, and previous plasma quasispecies, including the original inoculum, become undetectable. The question remains whether these ancestral variants exist in tissue reservoirs or if the immune system eliminates quasispecies from persistent infections. To examine this, an EIAV long-term inapparent carrier was immune suppressed with dexamethasone. Immune suppression resulted in increased plasma viral loads by approximately 10(4) fold. Characterization of pre- and post-immune suppression populations demonstrated continual envelope evolution and revealed novel quasispecies distinct from defined populations from previous disease stages. Analysis of the tissue and plasma populations post-immune suppression indicated the original infectious inoculum and early populations were undetectable. Therefore, the host immune system apparently eliminated a diverse array of antigenic variants, but viral persistence was maintained by relentless evolution of new envelope populations from tissue reservoirs in response to ongoing immune pressures.     

HIV-1 compartmentalization in diverse leukocyte populations during antiretroviral therapy

CD4+ T lymphocytes are the primary target of human immunodeficiency virus type 1 (HIV-1), but there is increasing evidence that other immune cells in the blood, including CD8+ T lymphocytes and monocytes, are also productively infected. The extent to which these additional cellular reservoirs contribute to ongoing immunodeficiency and viral persistence during therapy remains unclear. In this study, we conducted a detailed investigation of HIV-1 diversity and genetic structure in CD4+ T cells, CD8+ T cells, and monocytes of 13 patients receiving highly active antiretroviral therapy (HAART). Analysis of molecular variance and nonparametric tests performed on HIV-1 envelope sequences provided statistically significant evidence of viral compartmentalization in different leukocyte populations. Signature pattern analysis and predictions of coreceptor use provided no evidence that selection arising from viral tropism was responsible for the genetic structure observed. Analysis of viral genetic variation in different leukocyte populations demonstrated the action of founder effects as well as significant variation in the extent of genetic differentiation between subpopulations among patients. In the absence of evidence for leukocyte-specific selection, these features were supportive of a metapopulation model of HIV-1 replication as described previously among HIV-1 populations in the spleen. Compartmentalization of the virus in different leukocytes may have significant implications for current models of HIV-1 population genetics and contribute to the highly variable way in which drug resistance evolves in different individuals during HAART.     

Limited Immune Reconstitution at Intermediate Stages of HIV-1 Infection During One Year of Highly Active Antiretroviral Therapy in Antiretroviral-Naive Versus Non-Naive Adults

Although several reports have attributed the clinical benefits of highly active antiretroviral therapy (HAART) to a possible immune restoration, long-term data are still scarce and most derive from patients with either advanced or very early stages of HIV infection. In the present study, changes in lymphocyte subsets, activation markers, and adhesion molecules in CD4+ and CD8+ lymphocytes were carefully monitored over a 1-year period in 27 HIV-infected adults at an intermediate stage of HIV infection. Cytokine-producing patterns were also studied. In these patients the HIV viral load disappeared by month 4 of HAART. Only limited immunological changes were observed: an incomplete recovery of naive CD4+ T cells, a less activated state of CD8+ T cells, and a repopulation of IL-2- and IFN-γ-producing CD4+ T cells. These changes were observed principally in patients with more advanced disease. Furthermore, HIV-infected subjects who had received HAART previously showed less marked immunological changes than antiretroviral-naive individuals. In conclusion, the sustained viral suppression during 1 year of HAART was accompanied by limited immunological recovery at intermediate stages of HIV infection. This finding indicates a need for longer HIV suppression in order to achieve effective recovery of the immune system. Electronic Publication     

IL-2 and IL-10 serum levels in HIV-1-infected patients with or without active antiretroviral therapy

We analyzed IL-2 and IL-10 serum levels in 26 HIV-1-infected patients naive of antiretroviral treatment and in 34 patients receiving highly active antiretroviral therapy (HAART). All patients without treatment were asymptomatic. When they were stratified according to levels of CD4+ T cells, IL-2 levels were significantly increased in patients with > or =200 CD4+/microl and IL-10 levels were significantly increased in patients with <200 CD4+/microl compared to controls. A significant negative correlation was observed between IL10 levels and CD4+ T-cell counts. No correlation was observed between IL-2 and IL-10 levels and viral load due to the wide range of variability in the number of HIV copies/ml present in the different patients. However, IL-2 levels were higher in patients with high viral load than in patients with low viral load. In patients with HAART, IL-2 and IL-10 levels were similar to the control group and no differences were detected respecting CD4+ T cells counts and viral load. Our findings show that the modifications in IL-2 and IL-10 serum levels in HIV-1-infected patients naive of antiretroviral treatment are associated with the progression of immunological damage. Furthermore, they show a dysbalance of type-1/type-2 cytokines with an involvement of type-2 cytokines in later stages of HIV infection. Cytokine dysregulation can be reversed by HAART in the context of immune restoration and viral suppression.     

T cell responses to highly active antiretroviral therapy defined by chemokine receptors expression, cytokine production, T cell receptor repertoire and anti-HIV T-lymphocyte activity

The immunological correlates of highly active antiretroviral therapy (HAART)-induced suppression of human immunodeficiency virus type 1 (HIV-1) replication have been investigated. 20 HIV-1-infected patients with mean CD4+ T cell count of 298/microl, plasma viral load of 4.7 log10 copies/ml and naive for protease inhibitors (PI) were studied during12 months of HAART. An increased number of both CD4+ and CD8+ naive T cells and a normalization of the frequency of CCR5- and CXCR4-expressing CD4+ T cells were readily observed after starting therapy. Single cell analysis of cytokine production after 12 months of HAART showed an increased number of interleukin (IL)-2-, but not IL-4- and (IFN)-gamma-, producing T cells and a decreased percentage of CD8+ IFN-gamma + cells. A correlation between the frequency of IFN-gamma-producing T cells and that of memory, CCR5+ and CD95+ T cells was demonstrated in both CD4+ and CD8+ subsets. The diversity of T cell receptor (TCR) variable beta (BV) chain repertoire significantly increased after 12 months of HAART within the CD4+ but not the CD8+ T cell subset. However, the level of perturbation of the third complementarity-determining region (CDR3), was not significantly modified by effective therapy. The number of anti-HIV Gag and Pol cytotoxic T lymphocytes precursors (CTLp) decreased during HAART and highly correlated with the CD8 IFN-gamma response. Ameliorated clinical conditions were observed in all patients in absence of any opportunistic infections during all the study period. These observations indicate that a better restoration of immunity may be obtained in patients starting HAART at less advanced stages of the disease.     

Cd38 expression on Cd8+ T cells in Human immunodeficiency virus 1-positive adults treated with HAART

The aim of this study was to assess whether the density of CD38 antigen expression on CD8+ T cells can be used as a marker of activation of the immune system in Human immunodeficiency virus 1 (HIV-1)-positive patients treated with highly active antiretroviral therapy (HAART). T cell subsets, expression of CD38 antigen on CD8+T cells, HIV-1 viral load and stage of the disease were analyzed at baseline and after 12 months of HAART in 24 HIV-1-infected patients. Our data showed that the use of HAART is effective in reducing plasma viral load and in achieving a stable CD4+ count and percentage of CD8+/CD38+ cells. The percentages of CD8/CD38+ cells in HIV-1-infected patients at baseline and after 12 months of HAART were significantly higher than those of controls. Analysis of the density of CD38 expression revealed that it was due to CD8+/CD38+ subsets with low and medium density of antigen expression. Absolute number of CD4+ T cells correlated negatively with the percentage of CD8+/CD38+ cells at baseline of the study. Persistent up-regulation of the CD38 expression on CD8+ T cells and its correlation with the decreased CD4+ count despite the reduction of plasma viral load may reflect residual replication of HIV-1 in reservoirs. Thus, this immunological parameter can serve as a biological marker of HIV-1 infection and might have utility in clinical management of HIV-1-infected persons.     

The Fas/FasL system and T cell apoptosis in HIV-1-infected lymphoid tissue during highly active antiretroviral therapy.

Apoptosis has been proposed as a mechanism responsible for T cell depletion in HIV-1 infection. In the present study we have phenotyped apoptotic T cells in tonsillar lymphoid tissue from 11 HIV-1-infected patients by flow cytometry light-scatter characteristics during 48 weeks of highly active antiretroviral therapy (HAART). We found that the decline in tonsillar viral load was associated with a decrease in the proportion of apoptotic CD4+ and CD8+ T cells. CD4 cell apoptosis was predominantly seen within the memory CD28+ Fas+ FasL+ population. The increased level of apoptotic CD8+ T cells was found among activated Fas+ memory cells irrespective of CD28 and FasL expression. These T cell subsets were expanded in untreated infection, but normalized with therapy. We conclude that HIV-1 triggers FasL-mediated apoptosis of uninfected CD4+ T cells, whereas CD8+ T cell apoptosis is driven by chronic immune activation. Virus suppression reverses both of these mechanisms, contributing to immune reconstitution during HAART.     

Altered Coexpression of Lectin-Like Receptors CD94 and CD161 on NK and T Cells in HIV Patients

HIV patients either on highly active antiviral therapy (HAART) or therapy naive were analyzed for their CD56 phenotype and cytokine production in comparison to healthy controls (HC). Both NK cell populations (CD56(dim) and CD56(bright)) are found to be present in all groups with selectively decreased CD56(dim) NK cells in HAART naive patients. Patients on HAART exhibited significantly diminished numbers of CD161+CD56(dim) NK cells. CD56(dim) were equally potent in producing IFNgamma in all three groups. The number of TNFalpha+CD56(bright) NK cells from patients on HAART and TNFalpha+CD56(dim) NK cells from HAART naive patients was significantly reduced as compared to healthy controls. In summary our data revealed that functional capacities and coexpression patterns of lectin-like receptors on lymphocytes are differentially affected in HIV patients depending on the state of therapy (under HAART or HAART naive) or the cell type (NK or T cells), respectively.     

Progressive reduction of CMV-specific CD4+ T cells in HIV-1 infected individuals during antiretroviral therapy

Visualization of antigen-specific T cells has become an important tool in studying immune responses. The aim of this study was to analyze CMV-specific CD4+ T cells in healthy and HIV-infected individuals. Peripheral blood mononuclear cells (PBMC) were examined for antigen-induced intracellular cytokine responses. We found significant numbers of CMV-specific CD4+ T cells detectable in most CMV-IgG+ HIV-1 infected individuals, whereas CMV-specific CD4+ T cells could not be demonstrated in CMV-IgG- patients. Median frequency of CMV-specific CD4+ T cells were lower in HIV-infected subjects who had been treated with highly active antiretroviral therapy (HAART) for more than 1 year than in untreated HIV-infected individuals. In patients under therapy for less than 1 year median CMV-specific CD4+ T cell responder frequency was higher than in subjects treated for more than 1 year but lower than in untreated subjects. HIV suppression with HAART might lead to a progressive reduction of CMV-specific CD4+ T cells indicating an efficient elimination of an opportunistic pathogen.     

Differential upregulation of CD38 on different T-cell subsets may influence the ability to reconstitute CD4+ T cells under successful highly active antiretroviral therapy

BACKGROUND: Immune activation is an independent surrogate marker of CD4 T-cell depletion in HIV-infected patients. Highly active antiretroviral therapy (HAART) reduces disease progression as a direct consequence of suppressing HIV replication. Immune function does not normalize completely in most subjects on HAART, however, perhaps reflecting residual HIV replication. So far, it is unclear to what extent immune activation may influence the evolution of CD4 T-cell counts in patients on HAART. PATIENTS AND METHODS: The expression of CD38 on naive and memory subsets of CD4+ and CD8+ T cells was measured quantitatively by flow cytometry in 62 drug-naive HIV-positive and 30 HIV-uninfected controls. In addition, the evolution of this marker as well as that of some virologic parameters (plasma viremia and proviral load) and CD4 counts were assessed in 25 HIV-infected individuals who initiated HAART and were followed for 12 months. RESULTS: The mean level of CD38 on memory CD4+ and CD8+ T cells as well as in naive CD8+ cells was significantly higher in drug-naive HIV-positive subjects than in HIV-negative controls. Moreover, it was highly correlated with viral load titers. In patients on successful HAART, immune activation declined in all T-cell subsets, particularly among memory CD8+ cells. It remained elevated with respect to HIV-negative controls, however, even after 12 months of HAART. There was a significant correlation between the CD8+ T-cell activation decay and the increase of CD4+ T cells on HAART. Patients with the highest decline in CD8 activation were those showing the highest CD4 T-cell gains after 12 months of therapy. CONCLUSIONS: The level of CD38 expression on different T-cell subsets is differentially upregulated in drug-naive HIV-infected patients. After successful HAART, immune activation decreases in all T-cell subsets, although it still remains elevated in most cases after 12 months of HAART. The extent of immune deactivation under successful HAART correlates with the ability to reconstitute CD4 counts.     

Restoration of the immune system with anti-retroviral therapy

Clinical benefits of highly active anti-retroviral treatments (HAART) are increasingly evidenced by resolving opportunistic infections and malignancies, as well as declining hospitalization and mortality rates [1]. This suggests that potent and sustained suppression of viral replication, at least to some extent, is associated with reconstitution of the immune system even in adult patients treated at advanced stages of the disease. Increased susceptibility to opportunistic infections and tumors mainly results from the loss of memory CD4+ T cell reactivity against recall antigens which is an early event in HIV disease progression. Primary responses of naive CD4+ T cells against new pathogens are suppressed even earlier in the course of HIV disease, and the progressive depletion in naive CD4+ T cells reflects profound alterations in T cell regeneration capacities. Previous studies revealed that monotherapy with ritonavir, a protease inhibitor, resulted in a slight improvement in memory CD4+ T cell responses to recall Ags only when detectable prior to onset of therapy, suggesting that the loss of CD4+ T cell reactivity might be irreversible at advanced stages of the disease [2]. In contrast our group demonstrated more recently that restoration in CD4+ T cell reactivity to specific antigens was feasible when HAART was administered in progressors [3]. Here we address some of the questions raised by immune restoration with HAART when administered at advanced stages of the disease.     

Immune restoration disorders following HAART

Highly active antiretroviral therapy (HAART) leads to a profound and sustained suppression of viral replication, along with a rise in CD4+ cells in most HIV-infected patients. However, reports are accumulating of growing numbers of patients suffering from opportunistic infections despite recovery of CD4+ cells and plummeting viral loads as part of a new syndrome called immune restoration disease. We describe this syndrome in two patients and review the current literature.     

Long-term CD4+ T-cell response to highly active antiretroviral therapy according to baseline CD4+ T-cell count

Current treatment guidelines for HIV infection recommend a relatively late initiation of highly active antiretroviral therapy (HAART). Nevertheless, there is still a concern that immune recovery may not be as complete once CD4+ T cells have decreased below a certain threshold. This study addressed the long-term response of CD4+ T-cell counts in patients on HAART and analyzed the influence of baseline CD4+ T-cell counts, baseline viral load, and age. An observational analysis of evolution of CD4+ T cells in 861 antiretroviral therapy-naive chronic HIV-1-infected patients who started treatment consisting of at least 3 drugs in or after 1996 was performed. Patients were classified in 4 groups according to baseline CD4+ T cells: <200 cells/mm3, 200-349 cells/mm3, 350-499 cells/mm3, and >or=500 cells/mm3. The main outcome measures were proportion of patients with CD4+ T cells <200/mm3 and >500/mm3 at last determination and rate of CD4+ T-cell recovery. Patients were followed-up for a median of 173 weeks (interquartile range [IQR], 100-234). There were no differences in follow-up between the 4 groups. CD4+ T cells increased in the whole cohort from a median of 214 cells/mm3 (IQR, 90-355) to 499 cells/mm3 (IQR, 312-733) (P<0.001). Compared with the group with a baseline CD4+ T-cell count of >or=500/mm3, the relative risk of having a last determination of CD4+ T-cell counts >200 cells/mm3 was 0.79 (95% CI, 0.75-0.83), 0.92 (95% CI, 0.89-0.96) and 1 for baseline CD4+ T cells <200 cells/mm3, 200-349 cells/mm3, and 350-499 cells/mm3, respectively. The relative risk of having a last determination of CD4+ T-cell counts >500 cells/mm3 was 0.32 (95% CI, 0.27-0.39, P<0.001), 0.69 (95% CI, 0.60-0.79, P<0.001), and 0.94 (95% CI, 0.83-1.06, P=0.38) for baseline CD4+ T-cell counts <200 cells/mm3, 200-349 cells/mm3, and 350-0499 cells/mm3, respectively, compared with a baseline CD4+ T-cell count of >or=500 cells/mm3. The increase in CD4+ T cells from baseline was statistically significant and was maintained for up to 4 years of follow-up. This increase seemed to slow down after approximately 3 years and reached a plateau after 4-5 years of follow-up even in patients who achieved and maintained viral suppression in plasma. Long-term immune recovery is possible regardless of baseline CD4+ T-cell count. However, patients who start therapy with a CD4+ T-cell count <200 cells/mm3 have poorer immunologic outcome as measured by the proportion of patients with CD4+ T cells <200/mm3 or >500/mm3 at last determination. It seems that the immune recovery slows down after approximately 3 years of HAART and reaches a plateau after 4-5 years of HAART.     

Early reduction of the over-expression of CD40L, OX40 and Fas on T cells in HIV-1 infection during triple anti-retroviral therapy: possible implications for lymphocyte traffic and functional recovery.

Fas, CD40L and OX40 are members of the tumour necrosis factor (TNF) receptor superfamily with critical roles in T cell activation and death, B cell function, dendritic cell maturation and leucocyte traffic regulation. The aim of this study was to evaluate the effects of anti-retroviral therapy (HAART) on CD40L, OX40 and Fas expression on freshly isolated peripheral blood T cells by three-colour flow cytometry and compare them with lymphoproliferative responses, peripheral blood cell counts and viral load. Fourteen asymptomatic HIV-1+ patients treated with Lamivudine, Stavudine and Nelfinavir were prospectively investigated sequentially for 48 weeks. At baseline, patients exhibited significantly enhanced proportions and counts of CD40L+ and OX40+ cells within the CD4 subset which were corrected by weeks 8-16 of HAART. Interestingly, in the five patients showing viral load rebound during therapy in spite of increasing CD4 counts, the reduction of the levels of these costimulatory molecules was similarly maintained. Therapy induced a decrease in the over-expression of Fas, particularly in the CD4 subset where normal levels were reached at week 8. This reduction occurred in parallel with the major recovery of lymphoproliferative responses. Higher basal levels and lower reduction of Fas were associated with suboptimal suppression of viraemia. In conclusion, this previously undescribed increased expression of CD40L and OX40 may play a role in the HIV-associated pan-immune activation and represent a possible target for immunointervention, as suggested for several immunologically mediated diseases. Moreover, HAART induced an early correction of the over-expression of Fas, CD40L and OX40 in CD4 T cells which could be involved in the recovery of the cell traffic disturbances and in the T cell renewal capacity.