Increased turnover of T lymphocytes in HIV-1 infection and its reduction by antiretroviral therapy.

The mechanism of CD4(+) T cell depletion in human immunodeficiency virus (HIV)-1 infection remains controversial. Using deuterated glucose to label the DNA of proliferating cells in vivo, we studied T cell dynamics in four normal subjects and seven HIV-1-infected patients naive to antiretroviral drugs. The results were analyzed using a newly developed mathematical model to determine fractional rates of lymphocyte proliferation and death. In CD4(+) T cells, mean proliferation and death rates were elevated by 6.3- and 2.9-fold, respectively, in infected patients compared with normal controls. In CD8(+) T cells, the mean proliferation rate was 7.7-fold higher in HIV-1 infection, but the mean death rate was not significantly increased. Five of the infected patients underwent subsequent deuterated glucose labeling studies after initiating antiretroviral therapy. The lymphocyte proliferation and death rates in both CD4(+) and CD8(+) cell populations were substantially reduced by 5-11 weeks and nearly normal by one year. Taken together, these new findings strongly indicate that CD4(+) lymphocyte depletion seen in AIDS is primarily a consequence of increased cellular destruction, not decreased cellular production.     

Analysis of the human thymic perivascular space during aging

The perivascular space (PVS) of human thymus increases in volume during aging as thymopoiesis declines. Understanding the composition of the PVS is therefore vital to understanding mechanisms of thymic atrophy. We have analyzed 87 normal and 31 myasthenia gravis (MG) thymus tissues from patients ranging in age from newborn to 78 years, using immunohistologic and molecular assays. We confirmed that although thymic epithelial space (TES) volume decreases progressively with age, thymopoiesis with active T-cell receptor gene rearrangement continued normally within the TES into late life. Hematopoietic cells present in the adult PVS include T cells, B cells, and monocytes. Eosinophils are prominent in PVS of infants 2 years of age or younger. In the normal adult and the MG thymus, the PVS includes mature single-positive (CD1a(-) and CD4(+) or CD8(+)) T lymphocytes that express CD45RO, and contains clusters of T cells expressing the TIA-1 cytotoxic granule antigen, suggesting a peripheral origin. PBMCs bind in vitro to MECA-79(+) high endothelial venules present in the PVS, suggesting a mechanism for the recruitment of peripheral cells to thymic PVS. Therefore, in both normal subjects and MG patients, thymic PVS may be a compartment of the peripheral immune system that is not directly involved in thymopoiesis.     

Primary HIV-1 infection is associated with preferential depletion of CD4+ T lymphocytes from effector sites in the gastrointestinal tract

Given its population of CCR5-expressing, immunologically activated CD4(+) T cells, the gastrointestinal (GI) mucosa is uniquely susceptible to human immunodeficiency virus (HIV)-1 infection. We undertook this study to assess whether a preferential depletion of mucosal CD4(+) T cells would be observed in HIV-1-infected subjects during the primary infection period, to examine the anatomic subcompartment from which these cells are depleted, and to examine whether suppressive highly active antiretroviral therapy could result in complete immune reconstitution in the mucosal compartment. Our results demonstrate that a significant and preferential depletion of mucosal CD4(+) T cells compared with peripheral blood CD4(+) T cells is seen during primary HIV-1 infection. CD4(+) T cell loss predominated in the effector subcompartment of the GI mucosa, in distinction to the inductive compartment, where HIV-1 RNA was present. Cross-sectional analysis of a cohort of primary HIV-1 infection subjects showed that although chronic suppression of HIV-1 permits near-complete immune recovery of the peripheral blood CD4(+) T cell population, a significantly greater CD4(+) T cell loss remains in the GI mucosa, despite up to 5 yr of fully suppressive therapy. Given the importance of the mucosal compartment in HIV-1 pathogenesis, further study to elucidate the significance of the changes observed here is critical.     

Treatment of primary HIV-1 infection with cyclosporin A coupled with highly active antiretroviral therapy

Primary HIV-1 infection causes extensive immune activation, during which CD4(+) T cell activation supports massive HIV-1 production. We tested the safety and the immune-modulating effects of combining cyclosporin A (CsA) treatment with highly active antiretroviral therapy (HAART) during primary HIV-1 infection. Nine adults with primary HIV-1 infection were treated with CsA along with HAART. At week 8, all patients discontinued CsA but maintained HAART. Viral replication was suppressed to a comparable extent in the CsA + HAART cohort and in 29 control patients whose primary infection was treated with HAART alone. CsA restored normal CD4(+) T cell levels, both in terms of percentage and absolute numbers. The increase in CD4(+) T cells was apparent within a week and persisted throughout the study period. CsA was not detrimental to virus-specific CD8(+) or CD4(+) T cell responses. At week 48, the proportion of IFN-gamma-secreting CD4(+) and CD4(+)CCR7(-) T cells was significantly higher in the CsA + HAART cohort than in the HAART-alone cohort. In conclusion, rapid shutdown of T cell activation in the early phases of primary HIV-1 infection can have long-term beneficial effects and establish a more favorable immunologic set-point. Appropriate, immune-based therapeutic interventions may represent a valuable complement to HAART for treating HIV infection.     

Collagen deposition in HIV-1 infected lymphatic tissues and T cell homeostasis

Lymphatic tissues (LTs) are structurally organized to promote interaction between antigens, chemokines, growth factors, and lymphocytes to generate an immunologic response and maintain normal-sized populations of CD4(+) and CD8(+) T cells. Inflammation and tissue remodeling that accompany local innate and adaptive immune responses to HIV-1 replication cause damage to the LT architecture. As a result, normal populations of CD4(+) and CD8(+) T cells cannot be supported and antigen-lymphocyte interactions are impaired. This conclusion is supported herein following LT sampling before and during anti-HIV therapy in persons with acute, chronic, and late-stage HIV-1 infection. Among seven individuals treated with anti-retroviral therapy (ART) and four individuals deferring therapy we found evidence of significant paracortical T cell zone damage associated with deposition of collagen, the extent of which was inversely correlated with both the size of the LT CD4(+) T cell population and the change in peripheral CD4(+) T cell count with anti-HIV therapy. The HIV-1-associated inflammatory changes and scarring in LT both limit the ability of the tissue to support and reestablish normal-sized populations of CD4(+) T cells and suggest a novel mechanism of T cell depletion that may explain the failure of ART to significantly increase CD4(+) T cell populations in some HIV-1-infected persons.     

Long-term highly active antiretroviral therapy in chronic HIV-1 infection: evidence for reconstitution of antiviral immunity

In this study we investigated the long-term effect of highly active antiretroviral therapy (HAART) on HIV-specific CD4+ T-cell responses in comparison with virus-specific CD4+ T-cell responses against the persistent herpes viruses cytomegalovirus (CMV) and Epstein-Barr virus (EBV). To this end, HIV- and herpes virus-specific cellular immune responses were measured longitudinally in 10 seroconverters with long-term follow-up including 55 months of successful suppression of viral load by HAART. HIV- and CMV-specific CD4+ T cells producing interferon-gamma (IFNgamma) or interleukin-2 (IL-2) were analysed as well as proliferative capacity. EBV-specific CD4+ T cells were determined using a 12-day ex vivo assay. Initiation of HAART resulted in a transient increase of HIV-specific IL-2(+)IFNgamma(+)CD4(+) T cells and, to a lesser extent, IL-2(+)CD4(+) T cells. Long-term HAART resulted in an increase in HIV-, CMV- and EBV-specific CD4+ T-cell proliferative capacity. The increase in HIV- and herpes-virus-specific CD4+ T-cell proliferative capacity after 55 months of HAART suggests that the improved proliferative response is not specific for HIV, but reflects a more general improvement of antiviral immune responses, which is induced by HAART.     

Inhibition of simian/human immunodeficiency virus replication in CD4+ T cells derived from lentiviral-transduced CD34+ hematopoietic cells.

We examined the ability of a HIV-1-based vector (VRX494) encoding a 937-bp antisense HIV-1 envelope sequence to inhibit the replication of chimeric SIV/HIV-1 viruses encoding the HIV-1 envelope. Challenge of VRX494-transduced CEMx174 cells resulted in potent inhibition of HIV-1 and several SHIV strains. To evaluate the potential efficacy of the VRX494 vector for stem cell gene therapy, rhesus CD34(+) bone marrow cells were transduced with VRX494 and then cultured on thymus stroma to induce T cell differentiation. Transduction conditions for CD34(+) cells were optimized to yield high transduction efficiency with minimal effective multiplicity of infection. Purified CD4(+) GFP(+) T cells derived from VRX494-transduced CD34(+) cells strongly inhibited SHIV HXBC2P 3.2 and SHIV 89.6P replication compared to controls. Southern blot analysis of VRX494-transduced T cell clones revealed a subset of cells with multiple proviral copies per cell. Expression of GFP and the antisense inhibitor in VRX494-transduced cells was upregulated by Tat. Analysis of HIV-1 envelope sequences in VRX494-transduced cells revealed modifications consistent with those mediated by double-stranded RNA-dependent adenosine deaminase. These results indicate that the macaque/SHIV model should serve as a useful preclinical model to evaluate this lentiviral vector expressing an HIV-1 antisense inhibitor for stem cell gene therapy for AIDS.     

HIV-1 control after transient antiretroviral treatment initiated in primary infection: role of patient characteristics and effect of therapy

BACKGROUND: The occurrence of viral control after interruption of an antiretroviral treatment (ART) initiated during primary HIV-1 infection (PHI) is rare and the frequency and predictive factors of such a control are unknown. METHODS: Within the French ANRS PRIMO Cohort, 164 patients interrupted ART initiated during PHI. We compared patients whose viral load (VL) remained undetectable (<50 copies/ml) or low (50-500 copies/ml) 1 year after ART interruption to those who evidenced a rapid viral rebound. RESULTS: After ART interruption, VL remained undetectable for a median time of 4.5 years in 14 patients ('post-ART controllers') and low in another 14 patients for a median time of 1.5 years. Post-ART controllers also maintained higher CD4(+) T-cell counts compared to other patients. Female gender, a high CD4(+) T-cell count and low VL during PHI, and a high CD4(+) T-cell count and low HIV DNA levels at interruption, were associated with post-ART HIV control. Treatment characteristics did not differ between controllers and non-controllers. Post-ART controllers had lower specific CD8(+) T-cell frequencies and CD8(+) T-cell activation on ART and after ART interruption than non-controllers. CONCLUSIONS: Few patients maintain very low VL after interruption of treatment initiated during PHI. Early patient characteristics were the main factors of viral control, although early initiation of ART and the effect of ART on reservoir might contribute to control.     

CXCR5、sPD-1、Hcy在AIDS患者治疗过程中的动态变化及临床意义

目的探讨获得性免疫缺陷综合征(AIDS)患者抗逆转录病毒治疗(ART)过程中血清趋化因子受体5(CXCR5)、可溶性程序性细胞死亡受体-1(sPD-1)、同型半胱氨酸(Hcy)的变化及临床意义。方法选取AIDS患者120例(AIDS组),分别在AIDS患者治疗前1 d及治疗后3、6、12个月检测其人类免疫缺陷病毒(HIV)-1载量、CD4+T细胞绝对数及CXCR5、sPD-1、Hcy、血脂[三酰甘油(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)]水平;以体检健康者45名作为正常对照组。采用Pearson相关分析评估各项指标与CD4+T细胞绝对数、HIV-1载量的相关性。结果AIDS组治疗前sPD-1和Hcy水平均显著高于正常对照组(P<0.01),CXCR5、CD4+T细胞绝对数均显著低于正常对照组(P<0.01)。与治疗前比较,随着ART时间的延长,AIDS患者CD4+T细胞绝对数、CXCR5水平均显著升高(P<0.05),在治疗6个月时达到峰值;Hcy、TC、TG、LDL-C在治疗12个月时显著升高(P<0.05);HDL-C无变化;治疗3个月时HIV-1载量开始降低(P<0.05),治疗6个月时降低更为显著(P<0.05);治疗12个月时血清sPD-1水平显著降低(P<0.05)。Pearson相关分析结果显示,CD4+T细胞绝对数与CXCR5、Hcy水平均呈正相关(r值分别为0.192、0.401,P<0.05),与sPD-1呈负相关(r=-0.708,P<0.05);HIV-1载量与CXCR5、Hcy均呈负相关(r值分别为-0.682、-0.318,P<0.05),与sPD-1呈正相关(r=0.368,P<0.05)。结论动态监测AIDS患者ART过程中CD4+T细胞绝对数、HIV-1载量、CXCR5、sPD-1、Hcy和血脂的变化,有助于及时了解HIV感染的进展情况。     

Impact of opportunistic Mycobacterium tuberculosis infection on the phenotype of peripheral blood T cells of AIDS patients

While the detrimental consequences of opportunistic tuberculosis (TB) in the course and outcome of HIV-1 infection are well studied, little information about the impact of the mycobacterial infection on the phenotype of T lymphocytes is available. In this study we analyzed by cytofluorimetry the peripheral blood T cell phenotype of 13 patients with AIDS, 23 HIV-1 negative patients with active pulmonary TB, nine HIV-1/Mycobacterium tuberculosis coinfected individuals, and 21 age- and sex-matched healthy controls. CD4+ T cells were equally depleted in AIDS and coinfection (P<0.001). The findings suggest a rescuing effect of the added mycobacterial infection. CD3 T cell loss was not observed in coinfection, whereas it was severe in AIDS (P<0.001). Similar (albeit less striking) effects were observed with other markers (CD45RA, CD45RO, and CD27) that were diminished in CD4+ T cells of AIDS patients. Apparent detrimental effects of the added mycobacterial infection were the increased expression of the proapoptotic molecule CD95 on CD4+ T cells, and decreased expression of the major costimulatory molecule CD28 on CD8+ T cells. In this work we show that M. tuberculosis infection modifies the T cell phenotype of the HIV-1 infected individual.     

Naive T cells are dispensable for memory CD4+ T cell homeostasis in progressive simian immunodeficiency virus infection

The development of AIDS in chronic HIV/simian immunodeficiency virus (SIV) infection has been closely linked to progressive failure of CD4(+) memory T cell (T(M)) homeostasis. CD4(+) naive T cells (T(N)) also decline in these infections, but their contribution to disease progression is less clear. We assessed the role of CD4(+) T(N) in SIV pathogenesis using rhesus macaques (RMs) selectively and permanently depleted of CD4(+) T(N) before SIV infection. CD4(+) T(N)-depleted and CD4(+) T(N)-repleted RMs were created by subjecting juvenile RMs to thymectomy versus sham surgery, respectively, followed by total CD4(+) T cell depletion and recovery from this depletion. Although thymectomized and sham-treated RMs manifested comparable CD4(+) T(M) recovery, only sham-treated RMs reconstituted CD4(+) T(N). CD4(+) T(N)-depleted RMs responded to SIVmac239 infection with markedly attenuated SIV-specific CD4(+) T cell responses, delayed SIVenv-specific Ab responses, and reduced SIV-specific CD8(+) T cell responses. However, CD4(+) T(N)-depleted and -repleted groups showed similar levels of SIV replication. Moreover, CD4(+) T(N) deficiency had no significant effect on CD4(+) T(M) homeostasis (either on or off anti-retroviral therapy) or disease progression. These data demonstrate that the CD4(+) T(N) compartment is dispensable for CD4(+) T(M) homeostasis in progressive SIV infection, and they confirm that CD4(+) T(M) comprise a homeostatically independent compartment that is intrinsically capable of self-renewal.     

Dynamics of the pool of infected resting CD4 HLA-DR- T lymphocytes in patients who started a triple class five-drug antiretroviral regimen during primary HIV-1 infection

Starting standard antiretroviral therapy within 10 days after the onset of a primary HIV-1 infection cannot prevent the establishment of a reservoir of HIV-1-infected memory CD4 T cells. Here we studied the reservoir of HIV-1-infected memory CD4 T cells in four patients who started a triple class, five-drug regimen during primary HIV-1 infection. There was a strong correlation between the proportion of productively infected CD4 HLA-DR- T lymphocytes and plasma HIV-1 RNA levels (r=0.852; P<0.001) during the first 24 weeks of therapy. Within 45 weeks of treatment, in three of the four patients the proportion of productively infected CD4 HLA-DR- T lymphocytes was reduced below the level of quantification. In the fourth patient the cellular reservoir remained quantifiable. In two patients who stopped therapy 44 weeks after initiation an immediate rebound of the plasma HIV-1 RNA level and the proportion of productively infected CD4 HLA-DR- T lymphocytes occurred. In conclusion, initiation of a potent five-drug, triple class regimen during primary HIV-1 infection does not result in virus-specific immune control upon discontinuation of therapy after 44 weeks. Therefore, longer or even stronger suppression of viral replication might be necessary to achieve this goal in primary HIV-1 infection.     

Expression of CD69 on T-cell subsets in HIV-1 disease

CD69 is the earliest activation marker newly synthesized and expressed during T lymphocyte activation. In this study, a whole-blood flow-cytometry-based assay was used to assess expression of the activation antigen CD69 on CD4 and CD8 T lymphocytes, and the co-expression of CD69 and CD28 on T cells. The expression of CD69 was studied in both unstimulated and in phytohaemagglutinin (PHA)- or anti-CD(3)/CD(28)-stimulated, 4-h culture, samples. The production of IL-2, IFN-gamma or both cytokines, in CD69(+) T cells, in response to Staphylococcus enterotoxin B was also tested. Fifty-three HIV-1-infected and 21 healthy volunteers participated in this study. In both PHA- and anti-CD(3)/CD(28)-stimulated cultures the percentage of CD69 on CD3(+)CD4(+) T cells was significantly lower in AIDS (and non-responders to HAART) versus healthy controls and the other HIV-1(+) groups. A decrease of CD69(+)CD28(+) T cells after PHA or MoAbs stimulation is noticed in AIDS. No difference in cytokine production was noticed between healthy volunteers and HIV-1(+) patients. Our results suggest that the expression of CD69 is affected only in the AIDS stage and in the non-responders to HAART patients.     

Immunophenotypic analyses of CD34(+) cell subsets in bone marrow from HIV-infected patients during highly- active antiretroviral therapy

BACKGROUND: Because increased bone marrow lymphopoiesis might contribute to immunologic reconstitution during highly-active antiretroviral therapy (HAART), we examined the effect of HAART on CD34(+) cell subsets in bone marrow from HIV-infected patients. MATERIALS AND METHODS: In 12 HIV-infected patients, bone marrow and peripheral blood were collected before then 4 and 26 weeks after initiating HAART. Bone marrow in 28 HIV-seronegative controls was also examined. Immunophenotypic analyses of CD34(+) cell subsets in bone marrow were performed by flow cytometry. RESULTS: Our main findings in bone marrow were: (i) HIV-infected patients had increased proportions of CD34(+)cells expressing T- and B-cell markers before initiating HAART; (ii) in contrast, these patients had decreased proportions of CD34(+) cells expressing myeloid-associated markers; (iii) although HAART induced an increase in peripheral T-cell counts, the percentage of CD34(+)cells expressing T-cell markers tended to decrease during such therapy; (iv) HAART induced a decrease in serum IgG accompanied by a slight decrease in the proportion of CD34(+)cells expressing B-cell markers; (v) in contrast, HAART induced a significant increase in peripheral granulocyte counts, accompanied by a slightly increased proportion of CD34(+) cells expressing myeloid-associated molecules. CONCLUSION: Our findings are compatible with an HIV-related block in T-cell differentiation, leading to accumulation of T-cell progenitors in bone marrow, and such a block may be removed by HAART.     

Kinetics of Gag-specific cytotoxic T lymphocyte responses during the clinical course of HIV-1 infection: a longitudinal analysis of rapid progressors and long-term asymptomatics

To gain more insight into the role of HIV-1-specific cytotoxic T lymphocytes (CTL) in the pathogenesis of AIDS, we investigated temporal relations between HIV-1 Gag-specific precursor CTL (CTLp), HIV-1 viral load, CD4+ T cell counts, and T cell function. Six HIV-1-infected subjects, who were asymptomatic for more than 8 yr with CD4+ counts > 500 cells/mm3, were compared with six subjects who progressed to AIDS within 5 yr after HIV-1 seroconversion. In the long-term asymptomatics, persistent HIV-1 Gag-specific CTL responses and very low numbers of HIV- 1-infected CD4+ T cells coincided with normal and stable CD4+ counts and preserved CD3 mAb-induced T cell reactivity for more than 8 yr. In five out of six rapid progressors Gag-specific CTLp were also detected. However, early in infection the number of circulating HIV-1-infected CD4+ T cells increased despite strong and mounting Gag-specific CTL responses. During subsequent clinical progression to AIDS, loss of Gag- specific CTLp coincided with precipitating CD4+ counts and severe deterioration of T cell function. The possible relationships of HIV-1 Gag-specific CTLp to disease progression are discussed.     

Delayed recovery of effector memory CD4+ T cells by highly active antiretroviral therapy in a patient with HIV-1 infection

Effector memory T cells, which are potentially important in the protection against various pathogens, have been shown to be CCR7 negative. We report a case with HIV-1 infection in whom the change in the cell numbers of the subsets of CD4+ T cells, including CCR7 negative memory CD4 + T cells, in peripheral blood was monitored for more than one year after the initiation of highly active antiretroviral therapy. Percentage of each subsets in lymphocytes was measured by triple staining on lymphocyte fraction in flow-cytometry. The numbers of total CD4+ T cell, naive T cells, and CCR7 positive memory T cells successfully increased within half a month after the initiation of the therapy. Instead, the recovery of the cell number in CCR7 negative memory T cells delayed, and continued to increase untill 10 months after the initiation of the therapy. It suggests the possibility of delay in recovery of immune systems after the initiation of the therapy in HIV-1-infected patients, despite the prompt recovery of total CD4 + T cells.     

Growth hormone enhances thymic function in HIV-1-infected adults

Growth hormone (GH) is an underappreciated but important regulator of T cell development that can reverse age-related declines in thymopoiesis in rodents. Here, we report findings of a prospective randomized study examining the effects of GH on the immune system of HIV-1-infected adults. GH treatment was associated with increased thymic mass. In addition, GH treatment enhanced thymic output, as measured by both the frequency of T cell receptor rearrangement excision circles in circulating T cells and the numbers of circulating naive and total CD4(+) T cells. These findings provide compelling evidence that GH induces de novo T cell production and may, accordingly, facilitate CD4(+) T cell recovery in HIV-1-infected adults. Further, these randomized, prospective data have shown that thymic involution can be pharmacologically reversed in humans, suggesting that immune-based therapies could be used to enhance thymopoiesis in immunodeficient individuals.     

HIV-1 integrase inhibitors: a review of their chemical development

Highly active antiretroviral therapy (HAART) significantly decreases plasma viral load, increases CD4+ T-cell counts in HIV-1-infected patients and has reduced progression to AIDS in developed countries. However, adverse side effects, and emergence of drug resistance, mean there is still a demand for new anti-HIV agents. The HIV integrase (IN) is a target that has been the focus of rational drug design over the past decade. In 2007, raltegravir was the first IN inhibitor approved by the US Food and Drug Administration for antiretroviral combination therapy, while another IN inhibitor, elvitegravir, is currently in Phase III clinical trials. This article reviews the development and resistance profiling of small molecule HIV-1 IN inhibitors.