IL-2 therapy and thymic production of naive CD4 T cells in HIV-infected patients with severe CD4 lymphopenia

OBJECTIVES: IL-2 therapy increases memory and naive CD4 T cells in HIV-infected patients, but its effect on thymopoiesis is unknown. To investigate this effect, we quantified T-cell receptor rearrangement excision circles (TREC) in CD4 T cells from lymphopenic AIDS patients treated with highly active antiretroviral therapy and IL-2. METHODS: CD4 cell subsets were evaluated by flow cytometry using anti-CD45RO/RA, CD62L, Ki67 and CD95 monoclonal antibodies. The proportion of recent thymic emigrant had been quantified by a real-time polymerase chain reaction assay for signal joint TREC in peripheral blood mononuclear and purified CD4 T cells. RESULTS: At initiation of IL-2, TREC copies/microl of blood were correlated with naive T cell numbers and age. Both naive and TREC numbers/microl significantly increased over time in all patients, with a wide range of TREC increases. Higher percentages of CD4+CD45RO-negative cells positive for the Ki67 cell-cycle marker were found in patients with a low TREC increase, but remained stable under IL-2. TREC and naive cell recovery were correlated; they also correlated with the numbers of TREC and naive cells at the start of IL-2, and with age, suggesting a thymic origin for naive T-cell recovery. A mathematical model showing the linear recovery of naive cells and TREC under IL-2 also strongly suggested that a naive T-cell increase reflects thymic export and involves little net death and proliferation. CONCLUSION: Although we cannot rule out a mechanism of altered proliferation or death rate, the thymus plays an important role in the long-term recovery of naive T cells under IL-2 therapy.     

Impaired base excision repair and accumulation of oxidative base lesions in CD4+ T cells of HIV-infected patients

Several studies have reported enhanced oxidative stress in patients with HIV infection. An important pathophysiologic consequence of increased oxidative stress is endogenous DNA damage, and the base excision repair pathway is the most important mechanism to withstand such deleterious effects. To investigate the role of base excision repair in HIV infection, we examined 7,8-dihydro-8-oxoguanine (8-oxoG) levels as a marker of oxidative DNA damage and DNA glycosylase activities in CD4(+) and CD8(+) T cells of HIV-infected patients and controls. These results showed that the HIV-infected patients, particularly those with advanced disease, had increased levels of 8-oxoG in CD4(+) T cells and marked declines in DNA glycosylase activity for the repair of oxidative base lesions in these cells. In contrast, CD8(+) T cells from HIV-infected patients, with 8-oxoG levels similar to those in healthy controls, showed enhanced capacity to repair oxidative DNA damage. Finally, highly active antiretroviral therapy induced increased glycosylase activity in CD4(+) T cells and normalized 8-oxoG levels. This imbalance between the accumulation of oxidative DNA damage and the capacity to repair such lesions in CD4(+) T cells may represent a previously unrecognized mechanism involved in the numerical and functional impairment of CD4(+) T cells in patients with HIV infection.     

Relationship of CD4+CD25+ regulatory T cells to immune status in HIV-infected patients

OBJECTIVE: To determine whether the frequencies of CD4+CD25+ regulatory T cells (T Reg) were related to immune status in HIV-infected patients. METHODS: Peripheral blood CD4 T-cell populations were examined for T-helper 1 cells (Th1), T-helper 2 cells (Th2), and T Reg by intracellular staining for interferon (IFN)-gamma and interleukin (IL)-4, and surface staining for CD25, respectively. The immunoregulatory properties of T Reg were assessed by measurement of the inhibitory effects of isolated CD4+CD25+ T Reg on CD4+CD25- T-cell proliferation. RESULTS: Isolated CD4+CD25+ T Reg from both HIV-infected patients and healthy controls strongly expressed CD45RO, HLA-DR, and FoxP3. HIV-infected patients with detectable plasma HIV-1 RNA showed a statistically significant increase in CD4+CD25high T Reg frequencies (P < 0.05) compared to healthy controls, with T Reg frequency inversely proportional to CD4 T-cell count (P < 0.01). However, in HIV-infected patients with undetectable plasma HIV-1 RNA, CD4+CD25high T Reg frequencies were not increased and were not related to CD4 T-cell counts. In both HIV-infected patient groups, T Reg frequency was inversely related to Th1 frequency (detectable HIV-1 RNA: P < 0.05; undetectable: P < 0.001), but positively related to Th2 frequency (detectable HIV-1 RNA: P < 0.01; undetectable: P < 0.001). T Reg activity was lower in patients with detectable plasma HIV-1 RNA than in patients with undetectable plasma HIV-1 RNA. CONCLUSIONS: Increased T Reg frequencies in peripheral blood were related to low peripheral blood CD4 T-cell counts and polarization toward Th2 immune responses in HIV-infected patients.     

Loss of EBNA1-specific memory CD4+ and CD8+ T cells in HIV-infected patients progressing to AIDS-related non-Hodgkin lymphoma

We previously observed a loss of Epstein-Barr virus (EBV)-specific CD8+ T cells in subjects progressing to EBV-related non-Hodgkin lymphoma (NHL), correlating with loss of CD4+ T cells. The aim of the present study was to determine the role of EBV-specific CD4+ T cells in the development of NHL during chronic HIV infection. To this end, CD4+ and CD8+ memory T cells, capable of both proliferation and subsequent interferon gamma (IFNgamma) production, directed against a latent (Epstein-Barr virus nuclear antigen 1 [EBNA1]) and a lytic (BamH fragment Z left frame 1 [BZLF1]) EBV antigen were studied longitudinally in 9 progressors to NHL, 4 progressors to non-EBV-related AIDS, and 4 slow progressors to AIDS. In all 3 groups we observed a decline of EBV-specific memory CD4+ and CD8+ T-cell responses during HIV infection. However, whereas latent antigen EBNA1-specific CD4+ T cells were lost well before diagnosis in all subjects who developed an AIDS-related NHL (and EBNA1-specific CD8+ T cells were significantly lower compared with the other groups), these cells were better preserved in progressors to non-EBV-related disease and slow progressors. Loss of EBNA1-specific T-cell immunity thus might be important for progression to NHL. Interestingly, BZLF1-specific T cells were not lost in all progressors to NHL, suggesting a different function of these cells in the surveillance of EBV-infected B cells.     

Increased CD4-positive monocytes in HIV-infected haemophilic patients

The monocyte–macrophage system is known to play a central role in HIV infection, and expression of CD4 on the surface of monocytes/macrophages is important, since this molecule is a key factor for the entrance of HIV into susceptible cells. In this paper we evaluated the expression of CD4 in monocytes of haemophiliac patients (He) who had been infected with HIV (HIV+ He) through transfusion of contaminated plasma concentrates. Thirty seropositive patients (HIV+ He), 10 seronegative He patients (HIV− He) and 20 voluntary normal blood donors were studied. Phenotypic evaluation of monocytes was performed by flow cytometry of peripheral blood stained with anti-CD45, -CD3, -CD4 and -CD14 monoclonal antibodies. The percentage of CD4 monocytes was increased in all HIV+ patient groups, but it was highest in those belonging to Groups III and IV A of the CDC classification. Furthermore, the median of fluorescence intensity of CD4+ monocytes from individual patients was shifted to the right, indicating expression of increased numbers of CD4 molecules on the cell membrane of monocytes. This could in turn favour HIV infection and viral persistence, facilitating in vivo dissemination of the virus.     

MicroRNA-31对 HIV感染者CD4+ T细胞CD69表达的影响及机制

目的　探讨微小RNA（microRNA, miR）-31对HIV感染者CD4+ T细胞表面CD69表达的影响及作用机制。方法　通过流式细胞仪分析健康对照与HIV感染者的CD4+ T细胞活化后CD69表达情况。在健康人外周血单个核细胞中转染antagomir-miR-31抑制miR-31表达，观察CD4+ T细胞活化后CD69表达情况。采用生物信息学方法预测miR-31靶基因及相关通路，并在293T细胞系中过表达和抑制miR-31，通过实时荧光定量PCR检测相关靶基因的表达。结果　与健康对照相比，HIV感染者CD4+ T细胞在抗-CD3/CD28抗体刺激活化后CD69表达更低。抑制miR-31表达后，CD4+ T细胞活化时CD69的表达与对照相比显著下降。miR-31低表达后T细胞活化信号通路KSR2和DUSP7表达升高。结论　miR-31可以有效调节CD4+ T细胞表面CD69的表达，对HIV感染者早期免疫活化起重要作用。     

The effect of lamivudine on the replication of hepatitis B virus in HIV-infected patients depends on the host immune status (CD4 cell count)

We retrospectively analysed the effect of lamivudine on hepatitis B virus (HBV) in HIV-co-infected patients. In this small study we document a CD4 cell-dependent response on HBV replication with lamivudine therapy. In this respect, hepatitis B may be considered an opportunistic infection. Our finding may have important clinical consequences, and large prospective studies are necessary to investigate this further.     

Nadir CD4 cell count predicts neurocognitive impairment in HIV-infected patients

Though antiretroviral therapy attenuates neurocognitive disruption, impairment is still observed. We studied the nadir CD4 cell count as a predictor of neurocognitive changes. This cross-sectional study assessed 64 HIV-infected patients in two groups: G1 (n = 26, nadir CD4 < or =200 cells/ml) and G2 (n = 38, nadir CD4 >200 cells/ml). Percentages of patients showing neurocognitive impairment were compared according to different nadir CD4 cutoffs (200, 250, 300, and 350 cells/ml). From G2, we also took the subgroup of patients receiving treatment (G3) and compared this group with G1, in which all patients were being treated. Demographic and clinical variables were evaluated, as were differences in neurocognitive function. Neurocognitive impairment tended to be more prevalent in G1 [19 patients (73.1%)] than in G2 [20 (52.6%), p = 0.123]. When nadir CD4 cutoffs were compared, there was a trend toward more impaired subjects as the CD4 nadir decreased. Significantly different functioning was found in attention/working memory (digit span backward, p = 0.032) and executive functions (trail making test, part B, p = 0.020), with better performance in G2. Comparison between G1 and G3 confirmed those findings. We found differences in neurocognitive functioning in relation to nadir CD4 count in HIV-infected patients. Attention should be given to this value in the management of neurocognitive protection in HIV infection.     

CD4 T cell survival after intermittent interleukin-2 therapy is predictive of an increase in the CD4 T cell count of HIV-infected patients

Administration of interleukin (IL)-2 to human immunodeficiency virus (HIV)-infected patients leads to significant increases in CD4 T cell counts. We previously have shown that IL-2 induces increased proliferation and survival of CD4 T cells. Deuterium labeling studies were undertaken to study the relationship between IL-2-induced increases in the CD4 T cell count and the effects of IL-2 on cell proliferation and survival. A strong inverse correlation was noted between the rate of decay of the label in CD4 cells and increases in CD4 cell counts (R =or- 0.67; P<.001). This correlation was not seen with the level of proliferating cells. Although the CD4 cell count at baseline and the number of CD4 cells expressing CD25 were also predictive of increases in the CD4 cell count, the rate of decay remained the most statistically significant predictor in multivariate regression models. Thus, an increase in the survival of CD4 T cells appears to be the critical mechanism leading to sustained increases in the CD4 cell counts of HIV-infected patients receiving intermittent IL-2 therapy.     

CD4/CD45双色单平台法检测HIV感染者CD4~+ T淋巴细胞研究进展

CD4+T淋巴细胞计数是评价AIDS疾病进展和抗病毒治疗效果的重要指标。本文介绍了流式细胞仪CD4+T淋巴细胞计数方法的发展历史。将CD4/CD45双色单平台法的准确性、可靠性和经济性与其他方法进行了比较。表明该法简便、廉价且实用性强。同时介绍了当前适用于CD4/CD45双色单平台法的几款流式细胞仪的机型特点。     

Nevirapine-containing regimens in HIV-infected naive patients with CD4 cell counts of 200 cells/microl or less

We retrospectively evaluated the effectiveness of nevirapine-containing regimens in 118 naive patients initiating highly active antiretroviral therapy with CD4 cell counts S 200 cells/jl. After 24 months, 51% of patients continued nevirapine, 43 and 83% had viral loads < 50 copies/ml by intent-to-treat and on-treatment analyses, and a mean increase of +246 CD4 cells/microl occurred.More than 80% of patients who continued with nevirapine had viral loads < 50 copies/ml and CD4 cell counts > 200 cells/pl.     

Depletion in blood CD11c-positive dendritic cells from HIV-infected patients.

OBJECTIVES: To quantify blood dendritic cells from HIV-positive patients and to study the expression of functional molecules, in relation to HIV viral load, CD4 cell counts and antiretroviral treatment. DESIGN AND METHODS: Three-colour flow cytometry analysis was used to quantify blood dendritic cells without previous isolation from whole blood and to study the expression of functional molecules (MHC class II, CD11c, CD83, CD86) by dendritic cells from 30 HIV-positive patients, 15 of whom were treated with combined antiretroviral therapy (viral loads from undetectable to 5.4 log copies/ml, CD4 cell counts 1-1895 cells/mm3) and 11 non-infected controls. RESULTS: The median proportion of blood dendritic cells from HIV-positive patients was significantly decreased when the plasma viral load was above 200 copies/ml: 0.2% (0.1-1.1, n = 19) compared with 0.4% (0.2-0.8, n = 11) in patients with undetectable viral load whether they were treated or not, and to 0.4% (0.2-1.3, n = 11) in controls (P = 0.02). A major decrease of the CD11c positive dendritic cells was observed in all HIV-positive samples, with only 18% (mean; range: 0.3-80%, median 4.2%) compared with 44% (11-70%, median 42%) of control dendritic cells (P = 0.0006). In contrast, the proportion of dendritic cells expressing CD86, was slightly higher in HIV-positive patients than in controls (P = 0.03). CONCLUSIONS: The decreased proportion of blood dendritic cells correlated with virus replication and the lack of dendritic cells expressing CD11c are the first evidence of strong dendritic cell alterations in HIV-positive patients. Although the proportion of blood dendritic cells are in the normal range in treated HIV-positive patients with undetectable viral load, the CD11c alterations persist indicating that antiretroviral therapy might only partly correct the alterations of the circulating dendritic cells.     

Migration and accumulation of effector CD4+ T cells in nonlymphoid tissues

The migration of antigen-specific T cells to nonlymphoid tissues is thought to be important for the elimination of foreign antigens from the body. Here, we review the evidence that naive CD4(+) T cells are first activated by antigen presentation in secondary lymphoid organs, proliferate, and differentiate into effector cells capable of producing antimicrobial lymphokines. These effector cells then leave the secondary lymphoid organs and use newly acquired trafficking receptors to extravasate at sites of inflammation. We argue that antigen presentation is required to retain effector CD4(+) T cells in inflamed sites, and speculate on the antigen-presenting cells and adhesion pathways that are involved.     

Dysregulation of CD4+CD25+CD127lowFOXP3+ regulatory T cells in HIV-infected pregnant women

Pregnancy represents a major challenge to immunologic tolerance. How the fetal "semiallograft" evades maternal immune attack is unknown. Pregnancy success may involve alteration of both central (thymic) and peripheral tolerance mechanisms. HIV infection is characterized by CD4(+) T-cell depletion, chronic immune activation, and altered lymphocyte subsets. We studied immunologic consequences of pregnancy in 20 HIV-infected women receiving highly active antiretroviral therapy (HAART), and for comparison in 16 HIV-negative women. Lymphocyte subsets, thymic output, and cytokine profiles were measured prospectively during pregnancy and postpartum. A significant expansion of CD4(+)CD25(+)CD127(low)FoxP3(+) regulatory T cells indicating alteration of peripheral tolerance was seen during second trimester, but only in HIV-negative women. HIV-infected women had lower CD4 counts, lower thymic output and Th-2 cytokines, and more immune activation at all time points compared with controls. Immune activation was decreased in HIV-infected patients during pregnancy. In contrast, CD4 counts were increased in both groups. In conclusion, the study does not indicate that pregnancy adversely affects the immunologic course of HIV infection. However, despite HAART during pregnancy, HIV-infected women display different immunologic profiles from HIV-negative women, which may have importance for the induction of fetal-maternal tolerance and in part explain the increased risk of abortion in HIV-infected women.