Increased levels of activated subsets of CD4 T cells add to the prognostic value of low CD4 T cell counts in a cohort of HIV-infected drug users

Differential effects of antiretroviral treatment on immunity and gut microbiome composition in people living with HIV in rural versus urban Zimbabwe

BACKGROUND

The widespread availability of antiretroviral therapy (ART) has dramatically reduced mortality and improved life expectancy for people living with HIV (PLWH). However, even with HIV-1 suppression, chronic immune activation and elevated inflammation persist and have been linked to a pro-inflammatory gut microbiome composition and compromised intestinal barrier integrity. PLWH in urban versus rural areas of sub-Saharan Africa experience differences in environmental factors that may impact the gut microbiome and immune system, in response to ART, yet this has not previously been investigated in these groups. To address this, we measured T cell activation/exhaustion/trafficking markers, plasma inflammatory markers, and fecal microbiome composition in PLWH and healthy participants recruited from an urban clinic in the city of Harare, Zimbabwe, and a district hospital that services surrounding rural villages. PLWH were either ART naïve at baseline and sampled again after 24 weeks of first-line ART and the antibiotic cotrimoxazole or were ART-experienced at both timepoints.

RESULTS

Although expected reductions in the inflammatory marker IL-6, T-cell activation, and exhaustion were observed with ART-induced viral suppression, these changes were much more pronounced in the urban versus the rural area. Gut microbiome composition was the most highly altered from healthy controls in ART experienced PLWH, and characterized by both reduced alpha diversity and altered composition. However, gut microbiome composition showed a pronounced relationship with T cell activation and exhaustion in ART-naïve PLWH, suggesting a particularly significant role for the gut microbiome in disease progression in uncontrolled infection. Elevated immune exhaustion after 24 weeks of ART did correlate with both living in the rural location and a more Prevotella-rich/Bacteroides-poor microbiome type, suggesting a potential role for rural-associated microbiome differences or their co-variates in the muted improvements in immune exhaustion in the rural area.

CONCLUSION

Successful ART was less effective at reducing gut microbiome-associated inflammation and T cell activation in PLWH in rural versus urban Zimbabwe, suggesting that individuals on ART in rural areas of Zimbabwe may be more vulnerable to co-morbidity related to sustained immune dysfunction in treated infection. Video Abstract.

Antiretroviral treatment is less effective at reducing gut microbiome-associated inflammation and T cell activation in people living with HIV in rural versus urban Zimbabwe

The widespread availability of antiretroviral therapy (ART) for people living with HIV (PLWH) has dramatically reduced mortality and improved life expectancy. However, even with suppression of HIV-1 replication, chronic immune activation and elevated inflammation persist. Chronic immune activation has been linked to a pro-inflammatory gut microbiome composition, exacerbated by compromised intestinal barrier integrity that occurs after HIV infection. Individuals living in urban versus rural areas of sub-Saharan Africa have differences in environmental factors such as water source or diet that may impact gut microbiome composition, yet immune phenotype and gut microbiome composition response to ART in PLWH living in rural versus urban areas of sub-Saharan Africa have not been compared. Here, we measured immune phenotypes and fecal microbiome composition in PLWH and healthy participants recruited from the urban Mabvuku polyclinic in the city of Harare, Zimbabwe and the Mutoko District hospital located in a district 146 km from Harare that services surrounding rural villages. PLWH were either ART naïve at baseline and sampled again after 24 weeks of treatment with efavirenz/lamivudine/tenofovir disoproxil fumarate (EFV/3TC/TDF) and the prophylactic antibiotic cotrimoxazole or were ART experienced at both timepoints. Although expected reductions in the inflammatory marker IL-6, T-cell activation, and exhaustion were observed in individuals who had suppressed HIV-1 with treatment, these changes were significant only when considering individuals in the urban and not the rural area. Gut microbiome composition showed more marked differences from healthy controls in the ART experienced compared to ART naïve cohort, and consistent longitudinal changes were also observed in ART naïve PLWH after 24 weeks of treatment, including a reduction in alpha diversity and altered composition. However, gut microbiome composition showed a more pronounced relationship with chronic immune activation and exhaustion phenotypes in the ART naïve compared to ART experienced PLWH, suggesting a particularly significant role for the gut microbiome in disease progression in uncontrolled infection.

The CD38 glycohydrolase and the NAD sink: implications for pathological conditions

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

Lymphocyte subsets early predict mortality in a large series of hospitalized COVID-19 patients in Spain

The role of lymphocytes and their main subsets as prognostic factors of death in SARS-CoV-2-infected patients remains unclear, with no information obtained from patients outside China. We aimed to assess whether measuring lymphocyte subpopulations added clinical value to the total lymphocyte counting regarding mortality when they were simultaneously tested at hospital admission. Peripheral blood was analysed in 701 polymerase chain reaction (PCR)-confirmed consecutive patients by lysed-no washed flow cytometry. Demographic and clinical features were registered in electronic medical records. Statistical analysis was performed after a 3-month follow-up. The 112 patients who died were older and had significantly higher frequencies of known co-morbidities than survivor COVID-19 patients. A significant reduction in total lymphocytes, CD3+ , CD4+ , CD8+ and CD19+ counts and CD3+ percentage was found in the group of deceased patients (P < 0·001), while the percentage of CD56+ /CD16+ natural killer (NK) cells was significantly higher (P < 0·001). Multivariate logistic regression analysis showed a significantly increased risk of in-hospital death associated to age [odds ratio (OR) = 2·36, 95% confidence interval (CI) = 1·9-3·0 P < 0·001]; CD4+  T counts ≤ 500 cells/μl, (OR = 2·79, 95% CI = 1·1-6·7, P = 0·021); CD8+  T counts ≤ 100 cells/μl, (OR = 1·98, 95% CI = 1·2-3·3) P = 0·009) and CD56+ /CD16+ NK ≥ 30%, (OR = 1·97, 95% CI = 1·1-3·1, P = 0·002) at admission, independent of total lymphocyte numbers and co-morbidities, with area under the curve 0·85 (95% CI = 0·81-0·88). Reduced counts of CD4+ and CD8+ T cells with proportional expansion of NK lymphocytes at admission were prognostic factors of death in this Spanish series. In COVID-19 patients with normal levels of lymphocytes or mild lymphopenia, imbalanced lymphocyte subpopulations were early markers of in-hospital mortality.

Immune activation markers in individuals with HIV-1 disease and their correlation with HIV-1 RNA levels in individuals on antiretroviral therapy

Background

Currently CD4+ T lymphocyte counts and HIV-1 RNA levels are being utilized to predict outcome of human immunodeficiency virus (HIV) disease. Recently, the role of immune activation in HIV disease progression and response to treatment is being investigated. This study focused on the expression of CD38 and HLA-DR on lymphocyte subsets in various groups of HIV-infected individuals and to determine their association with HIV-1 disease progression.

Methods

Ninety-eight cases of patients with HIV/AIDS in different disease stages and twenty-four healthy HIV-negative individuals were included in the cross-sectional study. Their immune function and abnormal immune activation markers (CD38 & HLA-DR) were detected using a flowcytometer, and HIV-1 RNA levels in individuals receiving antiretroviral drugs were estimated.

Results

The immune activation marker levels were significantly different between patients with different disease stages (P < 0.001). A significant negative correlation was observed between peripheral blood CD4+ T cell counts and immune activation markers. Also, a significant positive correlation was observed between HIV-1 RNA levels and CD38+CD8+ T lymphocyte.

Conclusion

Immune activation markers (CD38 & HLA-DR) increase with disease progression. CD38+ on CD8+ T lymphocyte correlates well with HIV1 RNA levels in individuals failing on antiretroviral therapy.

Genetic variations in the host dependency factors ALCAM and TPST2 impact HIV-1 disease progression

OBJECTIVES

Recently, the activated leukocyte cell adhesion molecule (ALCAM) and tyrosylprotein sulfotransferase 2 (TPST2) have been identified as important host dependency factors (HDFs) for in-vitro HIV-1 replication. To determine whether these genes play a role in HIV-1 pathogenesis, we analysed whether naturally occurring genetic variations were associated with the clinical course of infection.

DESIGN/METHODS

Single nucleotide polymorphisms (SNPs) in ALCAM and TPST2 were analysed in a cohort of 304 HIV-1-infected men who have sex with men and survival analysis was used to determine their effect on the outcome of untreated HIV-1 infection. Flowcytometry was used to determine the effect of SNPs on CD4 T-cell activation prior to HIV-1 infection and 1 and 5 years after infection. In-vitro HIV-1 infections were performed to analyse the effect of the SNPs on HIV-1 replication.

RESULTS

We observed that the minor allele of rs1344861 in ALCAM was associated with accelerated disease progression, whereas the minor allele of rs9613199 in TPST2 was associated with delayed disease progression. In-vitro infection assays did not demonstrate any differences in HIV-1 replication associated with rs9613199. However, the increase in CD4 T-cell immune activation levels during HIV-1 infection was less pronounced in infected individuals homozygous for rs9613199, which is in agreement with delayed disease progression.

CONCLUSION

Our data demonstrate that ALCAM and TPST2 play a role in HIV-1 pathogenesis. SNPs in these genes, without known functional implications, had a major effect on disease progression, and therefore, these HDFs may be attractive and effective targets for new treatment strategies.

CD4+CD38+ central memory T cells contribute to HIV persistence in HIV-infected individuals on long-term ART

Background

Despite the effective antiretroviral treatment (ART) of HIV-infected individuals, HIV persists in a small pool. Central memory CD4⁺ T cells (Tcm) make a major contribution to HIV persistence. We found that unlike HLA-DR, CD38 is highly expressed on the Tcm of HIV-infected subjects receiving ART for > 5 years. It has been reported that the half-life of total and episomal HIV DNA in the CD4⁺CD38⁺ T cell subset, exhibits lower decay rates at 12 weeks of ART. Whether CD38 contributes to HIV latency in HIV-infected individuals receiving long-term ART is yet to be addressed.

Methods

Peripheral blood mononuclear cells (PBMCs) were isolated from the whole blood of HIV-infected subjects receiving suppressive ART. The immunophenotyping, proliferation and apoptosis of CD4⁺ T cell subpopulations were detected by flow cytometry, and the level of CD38 mRNA and total HIV DNA were measured using real-time PCR and digital droplet PCR, respectively. A negative binomial regression model was used to determine the correlation between CD4⁺CD38⁺ Tcm and total HIV DNA in CD4⁺ T cells.

Results

CD38 was highly expressed on CD4⁺ Tcm cells from HIV infected individuals on long-term ART. Comparing with HLA-DR⁻Tcm and CD4⁺HLA-DR⁺ T cells, CD4⁺CD38⁺ Tcm cells displayed lower levels of activation (CD25 and CD69) and higher levels of CD127 expression. The proportion of CD38⁺ Tcm, but not CD38⁻ Tcm cells can predict the total HIV DNA in the CD4⁺ T cells and the CD38⁺ Tcm subset harbored higher total HIV DNA copy numbers than the CD38⁻ Tcm subset. After transfected with CD38 si-RNA in CD4⁺ T cells, the proliferation of CD4⁺ T cells was inhibited.

Conclusion

The current date indicates that CD4⁺CD38⁺ Tcm cells contribute to HIV persistence in HIV-infected individuals on long-term ART. Our study provides a potential target to resolve HIV persistence.

Altered monocyte phenotype and dysregulated innate cytokine responses among people living with HIV and opioid-use disorder

Supplemental Digital Content is available in the text

Background:

Opioid-use disorders (OUD) and hepatitis C or B co-infection (HEP) are common among people living with HIV (PLHIV). The impact of OUD on innate and adaptive immunity among PLHIV with and without HEP is unknown.

Objectives:

To investigate the impact of OUD on monocyte and T-cell phenotypes, cytokine responses to lipopolysaccharide (LPS) and phytohemagglutinin (PHA), and plasma inflammatory markers, among PLHIV with and without HEP.

Methods:

Cross-sectional study enrolling PLHIV receiving ART, with and without OUD. Flow cytometry determined monocyte and T-cell phenotypes; LPS and PHA-induced cytokine production was assessed following LPS and PHA stimulation by multiplex cytokine array; plasma IL-6, soluble CD163, and soluble CD14 were measured by ELISA.

Results:

Twenty-two PLHIV with OUD and 37 PLHIV without OUD were included. PLHIV with OUD exhibited higher frequencies of intermediate (CD14⁺⁺CD16⁺) and nonclassical (CD14^dimCD16⁺) monocytes when compared with PLHIV without OUD (P = 0.0025; P = 0.0001, respectively), regardless of HEP co-infection. Soluble CD163 and monocyte cell surface CD163 expression was increased among PLHIV with OUD and HEP, specifically. Regardless of HEP co-infection, PLHIV with OUD exhibited reduced production of IL-10, IL-8, IL-6, IL-1alpha, and TNF-alpha in response to LPS when compared with PLHIV without OUD; PHA-induced production of IL-10, IL-1alpha, IL-1beta, IL-6, and TNF-alpha were also reduced among individuals with OUD.

Conclusion:

OUD among PLHIV are associated with altered monocyte phenotypes and a dysregulated innate cytokine response. Defining underlying mechanisms of opioid-associated innate immune dysregulation among PLHIV should be prioritized to identify optimal OUD treatment strategies.

HIV Disease Progression: Overexpression of the Ectoenzyme CD38 as a Contributory Factor?

Despite abundant evidence associating CD38 overexpression and CD4 T cell depletion in HIV infection, no causal relation has been investigated. To address this issue, a series of mechanisms are proposed, supported by evidence from different fields, by which CD38 overexpression can facilitate CD4 T cell depletion in HIV infection. According to this model, increased catalytic activity of CD38 may reduce CD4 T cells' cytoplasmic nicotin-amide adenine dinucleotide (NAD), leading to a chronic Warburg effect. This will reduce mitochondrial function. Simultaneously, CD38's catalytic products ADPR and cADPR may be transported to the cytoplasm, where they can activate calcium channels and increase cytoplasmic Ca2+ concentrations, further altering mitochondrial integrity. These mechanisms will decrease the viability and regenerative capacity of CD4 T cells. These hypotheses can be tested experimentally, and might reveal novel therapeutic targets. Also see the video abstract here https://youtu.be/k1LTyiTKPKs.

Casp8p41: The Protean Mediator of Death in CD4 T-cells that Replicate HIV

HIV cure is now the focus of intense research after Timothy Ray Brown (the Berlin patient) set the precedent of being the first and only person cured. A major barrier to achieving this goal on a meaningful scale is an elimination of the latent reservoir, which is thought to comprise CD4-positive cells that harbor integrated, replication-competent HIV provirus. These cells do not express viral proteins, are indistinguishable from uninfected CD4 cells, and are thought to be responsible for HIV viral rebound—that occurs within weeks of combination anti retroviral therapy (cART) interruption. Modalities to engineer transcriptional stimulation (reactivation) of this dormant integrated HIV provirus, leading to expression of cytotoxic viral proteins, are thought to be a specific way to eradicate the latently infected CD4 pool and are becoming increasingly relevant in the era of HIV cure. HIV protease is one such protein produced after HIV reactivation that cleaves procaspase-8 to generate a novel protein Casp8p41. Casp8p41 then binds to the BH3 domain of BAK, leading to BAK oligomerization, mitochondrial depolarization, and apoptosis. In central memory T cells (TCMs) from HIV-infected patients, an elevated Bcl-2/procaspase-8 ratio was observed, and Casp8p41 binding to Bcl-2 was associated with a lack of reactivation-induced cell death. This was reversed by priming cells with a specific Bcl-2 antagonist prior to reactivation, resulting in increased cell death and decreased HIV DNA in a Casp8p41-dependent pathway. This review describes the biology, clinical relevance, and implications of Casp8p41 for a potential cure.

CD38 Expression in a Subset of Memory T Cells Is Independent of Cell Cycling as a Correlate of HIV Disease Progression

In order to determine if the expression of the activation marker CD38 can correlate with HIV disease progression independently of cycling, we performed a cluster-based multivariate correlation analysis of total circulating CD4⁺ T cell counts and viral loads with frequencies of CD38 and Ki67 expression on CD4⁺ lymphocytes from patients with untreated HIV infection, stratified in maturation subpopulations, and subpopulation subsets defined by the expression of CXCR5, CXCR3, and CCR4. The frequencies of the activated phenotypes %CD38⁺ Ki67⁻ and %CD38⁺ Ki67⁺ of the CXCR5⁻ CXCR3⁻ CCR4⁺ (“pre-Th2”) central memory (T_CM) cell subset clustered together, comprising a significant negative correlate of total circulating CD4⁺ T cell counts and a positive correlate of viral load in multivariate analysis. Frequency of cycling-uncoupled CD38 expression in “pre-Th2” T_CM cells was a negative correlate of total circulating CD4⁺ T cell counts in univariate analysis, which was not the case of their %CD38⁺ Ki67⁺. CXCR5⁺ CXCR3⁻ CCR4⁻T_CM cells were underrepresented in patients, and their absolute counts correlated negatively with their %CD38⁺ Ki67⁻ but not with their % CD38⁺ Ki67⁺. Our results may imply that CD38 expression either reflects or participates in pathogenic mechanisms of HIV disease independently of cell cycling.

Dominant enrichment of phenotypically activated CD38(+) HLA-DR(+) CD8(+) T cells, rather than CD38(+) HLA-DR(+) CD4(+) T cells, in HIV/HCV coinfected patients on antiretroviral therapy

HIV infection may enhance immune-activation, while little is known regarding the role of HCV infection. This study investigates the impact of HCV in HIV coinfected patients with undetectable viraemia under HAART on the levels of peripheral T cell's immune-activation. We determined T lymphocytes subsets to characterize immune-activation defined as CD38 and/or HLA-DR expression in chronic monoinfected HCV, HIV, and HIV/HCV coinfected subjects. One hundred and fifty six patients were divided into three groups: (i) 77 HIV+ patients; (ii) 50 HCV+ patients; and (iii) 29 coinfected HIV/HCV patients. The level of CD4(+) was significantly higher in HCV+ than in HIV+ or in coinfected HIV/HCV subjects. The frequencies of CD4(+) CD38(+) /HLA-DR(-) , CD4(+) CD38(-) /HLA-DR(+) and CD4(+) CD38(+) /HLA-DR(+) in HIV+ patients were comparable to those measured in coinfected patients, but statistically higher than those observed in HCV+ subjects. The percentage of CD8(+) was comparable in HIV-1+ patients and coinfected HIV/HCV but the results obtained in both groups were significantly higher compared to the results obtained in HCV patients. The level of CD8(+) CD38(+) /HLA-DR(-) showed values lower in HIV+ patients than in that monoinfected HCV and coinfected HIV/HCV patients. The frequencies of CD8(+) CD38(-) /HLA-DR(+) were higher in HIV+ patients compared to HCV+ and coinfected HIV/HCV patients. HIV/HCV coinfected group showed highest levels of CD8(+) CD38(+) /HLA-DR(+) . HIV plays a pivotal role to determine the immune activation in the host. The role of HCV needs of further investigations but our data show that HCV mainly influences the immune-activation of the pool of CD8, but also probably plays a supporting additive effect on CD4 immune-activation. J. Med. Virol. 88:1347-1356, 2016. © 2016 Wiley Periodicals, Inc.

Potential role of serum BAFF as a biomarker in HIV infection

We evaluated the potential role of serum B-cell activating factor (BAFF) as a biomarker in HIV infection and analyzed the relationship between BAFF concentration and the immunophenotypic activation status of T-cells. We tested the hypothesis that higher serum BAFF concentrations are associated with risk for development of AIDS in HIV positive individuals. Forty-one HIV patients (CDC category A 17, category B 24) were evaluated retrospectively. Serum BAFF concentrations were assessed using a commercial enzyme-linked immunosorbent assay. Cox regression was used to estimate the probability for development of AIDS. Patients with higher BAFF concentrations (> 2100 pg/mL) were at greater risk of developing AIDS (relative hazard 5.69; p = 0.0033). BAFF levels were independently associated with risk of AIDS after adjustment by clinical risk factors. Serum BAFF was correlated with activated T-cell subsets and with neopterin levels. BAFF is a good candidate for further evaluation as a nonspecific surrogate marker in HIV infection.

Short communication: Apoptosis pathways in HIV-1-infected patients before and after highly active antiretroviral therapy: relevance to immune recovery

Investigations into apoptotic pathways, intrinsic and extrinsic, and the effects of highly active antiretroviral therapy (HAART) on T cell death via those pathways may provide insight into the mechanisms of and barriers to immune recovery. HIV-1-infected patients were enrolled into a randomized, controlled study of the immune effects of a lopinavir/ritonavir (LPV/r)-based versus an efavirenz (EFV)-based HAART regimen in antiretroviral-naive subjects with CD4(+) counts <350 cells/mm(3). Patients were randomized to receive TDF/FTC/EFZ or TDF/FTC plus LPV/r. Fourteen patients were enrolled and 10 patients completed 6 months of therapy as per the protocol. CD4(+) counts were measured before and during HAART therapy. We isolated T cell subsets to measure ex vivo apoptosis by propidium iodide staining. We also assessed caspase activation for the intrinsic and extrinsic pathways of apoptosis, as well as effector caspase activation. We also measured mitochondrial membrane potential. Cells were analyzed by flow cytometry. All patients had increased activation of caspase 8 (extrinsic pathway), caspase 9 (intrinsic pathway), effector caspases 3/7, and low mitochondrial membrane potential at baseline compared to controls. By 4 weeks, there was a decrease in activation of all caspases, but little further decrease by week 24. T cell mitochondrial membrane potential did not increase until week 12, but continued to increase until week 24. The only predictor of CD4(+) count increase was the increase in mitochondrial membrane potential of naive cells at 6 months (r=0.66, p=0.038). This suggests that positive selection of naive CD4(+) T cells in the thymus is the major determinant of CD4(+) recovery.

Beneficial effects of a switch to a Lopinavir/ritonavir-containing regimen for patients with partial or no immune reconstitution with highly active antiretroviral therapy despite complete viral suppression

The purpose of this study was to determine if switching to an Lopinavir/ritonavir (LPV/r)-containing regimen resulted in greater immune reconstitution in patients with immunologic failure despite complete viral suppression with highly active antiretroviral therapy (HAART). Twenty patients with partial or no immune response to HAART despite viral suppression were enrolled. Ten were randomized to stay on their current regimen and 10 were randomized to LPV/r plus their current NRTI backbone. T cell subsets, ex vivo apoptosis, and the percent of circulating cells with detectable intracellular HIV-1 RNA were measured. The mean increase in CD4(+) count at 6 months was 116/mm(3) (172-288) for the LPV/r-containing arm versus 32/mm(3) (264-296) for continuation regimens (p = 0.03). The number of patients with an increase ≥50 cells/mm(3) was also greater in the LPV/r arm (7/9 versus 2/10, p = 0.01). This paralleled a decrease in ex vivo apoptosis of naive CD4(+) T cells at 6 months (21.7-11.0% for the LPV/r arm versus 17.3-18.9% for the continuation arm, p = 0.04) and memory cells (21.1-14.1% for LPV/r versus 20.2-17.9% for continuation arm, NSS). Switching patients to an LPV/r-containing regimen improved CD4(+) counts in patients with prior immunologic failure, and this may be due to an effect of LPV/r on apoptosis.

Effects of antiretroviral therapy on immune function of HIV-infected adults with pulmonary tuberculosis and CD4+ >350 cells/mm3

BACKGROUND

Human immunodeficiency virus (HIV)-tuberculosis coinfection is associated with heightened immune activation, viral replication, and T cell dysfunction. We compared changes in T cell activation and function between patients receiving concurrent treatment for HIV-tuberculosis coinfection and those receiving treatment for tuberculosis alone.

METHODS

HIV-infected adults with tuberculosis and CD4(+) T cell counts >350 cells/mm(3) were randomized to receive tuberculosis treatment alone (control arm; n = 36) or 6 months of antiretroviral therapy (ART) concurrent with tuberculosis treatment (intervention arm; n = 38). HIV viral load, T cell subsets, T cell activation, and cytokine production were measured at enrollment and every 3 months for 12 months.

RESULTS

Differences in absolute CD4(+) and CD8(+) T cell counts were not observed between arms. Viral load was reduced while participants received ART; control patients maintained viral load at baseline levels. Both arms had significant reductions in T cell expression of CD38 and HLA-DR. Interferon-γ production in response to mitogen increased significantly in the intervention arm.

CONCLUSIONS

In HIV-infected adults with tuberculosis and CD4(+) T cell counts >350 cells/mm(3), both tuberculosis treatment and concurrent HIV-tuberculosis treatment reduce T cell activation and stabilize T cell counts. Concurrent ART with tuberculosis treatment does not provide additional, sustained reductions in T cell activation among individuals with preserved immunologic function.

Elite controllers display higher activation on central memory CD8 T cells than HIV patients successfully on HAART

T cell activation plays an important role in driving CD4 depletion during the course of HIV infection. There is scarce information about activation of different T cell subsets in HIV(+) individuals experiencing distinct disease progression. The activation of different CD4(+) and CD8(+) T cell subsets and its contribution to total T cell activation were examined measuring CD38 expression by flow cytometry in 120 HIV-infected individuals and 9 uninfected healthy controls. HIV-infected patients were divided into four groups: 11 elite controllers (EC), 14 viremic controllers (VC), 61 antiretroviral-naive typical progressors (TP), and 34 progressors with viral suppression (VS) under antiretroviral therapy. EC displayed significantly greater activation levels than VS, with a higher contribution of central memory subsets to the activation of total CD8 T cells (p = 0.002). The activation of central memory CD8(+) T cells significantly correlated with viral load in TP regardless of CD4 counts. In contrast with VS, proviral load was undetectable in all EC. Compared to VS, EC display abnormal and higher activation levels of different CD8(+) T cell subsets. Factors other than the size of the viral reservoir should explain the high level of activation of central memory CD8(+) T cells characteristically seen in HIV(+) individuals with spontaneous control of viral replication.

HIV-specific CD4+ T cells may contribute to viral persistence in HIV controllers

BACKGROUND

Human immunodeficiency virus (HIV)--infected individuals maintaining plasma HIV RNA levels <75 copies/mL in the absence of therapy ("HIV controllers") often maintain high HIV-specific T cell responses, which likely contribute to the control of viral replication. Despite robust immune responses, these individuals never eradicate HIV infection. We hypothesized that HIV-specific CD4(+) T cells might serve as target cells for HIV, contributing to viral persistence in this setting.

METHODS

We measured frequencies of activated (CD38(+) HLA-DR(+)) and HIV Gag-specific CD4(+) and CD8(+) T cells and plasma- and cell-associated levels of HIV RNA and DNA in a cohort of 38 HIV controllers.

RESULTS

Although there was no evidence of a relationship between the extent of low-level viremia and the frequency of either activated or HIV-specific CD4(+) T cells, controllers with higher HIV-specific CD4(+) T cell frequencies had higher cell-associated HIV DNA levels (ρ = 0.53; P = .019). Higher activated CD4+ T cell frequencies were also associated with higher levels of cell-associated DNA (P = .027) and RNA (P = .0096). However, there was no evidence of a relationship between cell-associated HIV RNA or DNA levels and HIV-specific CD8(+) T cell frequencies.

CONCLUSIONS

These data support a model in which strong HIV-specific CD4(+) T cell responses in HIV controllers, while contributing to a potent adaptive immune response, may also contribute to viral persistence, preventing the natural eradication of HIV infection.

Immune reconstitution in severely immunosuppressed antiretroviral-naive HIV type 1-infected patients using a nonnucleoside reverse transcriptase inhibitor-based or a boosted protease inhibitor-based antiretroviral regimen: three-year results (The Advanz Trial): a randomized, controlled trial

Late diagnosis of HIV-1 infection is quite frequent in Western countries. Very few randomized clinical trials to determine the best antiretroviral treatment in patients with advanced HIV-1 infection have been performed. To compare immune reconstitution in two groups of very immunosuppressed (less than 100 CD4(+) cells/microl), antiretroviral-naive HIV-1-infected adults, 65 patients were randomly assigned in a 1:1 ratio to receive zidovudine + lamivudine + efavirenz (group A, 34 patients) or zidovudine + lamivudine + ritonavir-boosted indinavir (group B, 31 patients). The median (interquartile range) CD4(+) cell increase after 12 and 36 months was +199 (101, 258) and +299 (170, 464) cells/microl in the efavirenz arm and +136 (57, 235) and +228 (119, 465) cells/microl in the ritonavir-boosted indinavir arm (p > 0.05 for all time points). The proportion (95% confidence interval) of patients achieving HIV-1 RNA levels under 50 copies/ml was significantly greater in the efavirenz arm at 3 years by the intention-to-treat analysis [59% (41%, 75%) vs. 23% (10%, 41%)], whereas no differences were found in the on-treatment analysis. Immune activation (CD8(+)CD38(+) and CD8(+)CD38DR(+) T cells) was significantly lower for the efavirenz arm from month 6 to month 24. Adverse events were more frequent in the ritonavir-boosted indinavir arm. Almost all cases of disease progression and death were observed in the first year of treatment, with no significant differences between the two arms (p = 0.79 by the log-rank test). At 1 and 3 years, the immune reconstitution induced by an efavirenz-based regimen in very immunosuppressed patients was at least as potent as that induced by a ritonavir-boosted protease inhibitor-based antiretroviral regimen.

Limited CD4+ T cell proliferation leads to preservation of CD4+ T cell counts in SIV-infected sooty mangabeys

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections result in chronic virus replication and progressive depletion of CD4+ T cells, leading to immunodeficiency and death. In contrast, 'natural hosts' of SIV experience persistent infection with high virus replication but no severe CD4+ T cell depletion, and remain AIDS-free. One important difference between pathogenic and non-pathogenic infections is the level of activation and proliferation of CD4+ T cells. We analysed the relationship between CD4+ T cell number and proliferation in HIV, pathogenic SIV in macaques, and non-pathogenic SIV in sooty mangabeys (SMs) and mandrills. We found that CD4+ T cell proliferation was negatively correlated with CD4+ T cell number, suggesting that animals respond to the loss of CD4+ T cells by increasing the proliferation of remaining cells. However, the level of proliferation seen in pathogenic infections (SIV in rhesus macaques and HIV) was much greater than in non-pathogenic infections (SMs and mandrills). We then used a modelling approach to understand how the host proliferative response to CD4+ T cell depletion may impact the outcome of infection. This modelling demonstrates that the rapid proliferation of CD4+ T cells in humans and macaques associated with low CD4+ T cell levels can act to 'fuel the fire' of infection by providing more proliferating cells for infection. Natural host species, on the other hand, have limited proliferation of CD4+ T cells at low CD4+ T cell levels, which allows them to restrict the number of proliferating cells susceptible to infection.

Acute-phase CD4+ T-cell proliferation and CD152 upregulation predict set-point virus replication in vaccinated simian–human immunodeficiency virus strain 89.6p-infected macaques

Human immunodeficiency virus (HIV) infection in humans and simian immunodeficiency virus (SIV) infection in macaques are accompanied by a combined early loss of CCR5 (CD195)-expressing CD4+ memory T cells, loss of T-helper function and T-cell hyperactivation, which have all been associated with development of high virus load and disease progression. Here, a cohort of vaccinated simian–human immunodeficiency virus strain 89.6p (SHIV89.6p)-infected rhesus macaques, where preferential depletion of these memory T-cell subsets does not take place and CD4+ T cells are relatively well maintained, was used to study the role of hyperactivation as an independent factor in the establishment of set-point virus load. In the acute phase of the infection, a transient loss of CD4+ T cells, as well as strong increases in expression of proliferation and activation markers on CD4+ and CD8+ T cells, together with CD152 expression on CD4+ T cells, were observed. Peak expression levels of these markers on CD4+ T cells, but not on CD8+ T cells, were correlated with high virus replication in the chronic phase of the infection. In addition, the peak expression level of these markers was correlated inversely with acute-phase, but not chronic-phase, HIV/SIV-specific gamma interferon responses. These data highlight a central role for an acute but transient CD4 decrease, as well as CD4+ T-cell activation, as independent factors for prediction of set-point levels of virus replication.

Replication capacity in relation to immunologic and virologic outcomes in HIV-1-infected treatment-naive subjects

OBJECTIVES

To evaluate the association between baseline (BL) replication capacity (RC) (RCBL) and immunologic/virologic parameters (at BL and after 48 weeks on therapy) in HIV-1-infected subjects initiating antiretroviral therapy.

METHODS

RCBL was determined using a modified Monogram PhenoSense HIV drug susceptibility assay on plasma HIV-1 from 321 treatment-naive subjects from AIDS Clinical Trials Group 384. Univariate and multivariable analyses were performed to determine the association of RCBL with BL and on-therapy virologic and immunologic outcomes.

RESULTS

Higher RCBL was associated with lower baseline CD4 (CD4BL) (r = -0.23, P < 0.0001), higher baseline HIV-1 RNA (r = 0.25, P < 0.0001), higher CD4BL activation percent (r = 0.23, P < 0.0001), and lower CD4BL memory count (r = -0.21, P = 0.0002). In a multivariable model, week 48 CD4 increase (DeltaCD448) was associated with lower CD4BL memory count and higher CD4BL-naive percent (P = 0.004, P = 0.015, respectively). The interaction between CD4BL and RCBL was significant (P = 0.018), with a positive association between RCBL and DeltaCD448 in subjects with higher CD4BL and a negative association at lower absCD4BL.

CONCLUSIONS

At baseline, higher RC was significantly associated with higher HIV-1 RNA, higher CD4 cell activation, lower CD4 cell count, and lower CD4 memory cell count. These factors may interact, directly or indirectly, to modify the extent to which CD4 recovery occurs in patients starting antiretroviral therapy at different CD4BL counts.

Down-regulation of interleukin-7 receptor (CD127) in HIV infection is associated with T cell activation and is a main factor influencing restoration of CD4(+) cells after antiretroviral therapy

BACKGROUND

Factors influencing the depletion of CD4(+) cells and the restoration of CD4(+) cells after antiretroviral therapy are not completely understood. Recently, attention has been paid to interleukin (IL)-7 and its receptor (CD127). We analyzed the influence of T cell activation and of suppression of viremia with antiretroviral therapy on this system, as well as its role in CD4(+) cell restoration after long-term antiretroviral therapy.

METHODS

IL-7 levels and CD127 expression on several subsets of CD4(+) and CD8(+) T lymphocytes and the activation status (CD38) of these cells were examined at baseline and during 24 months of complete viral suppression under highly active antiretroviral therapy (HAART).

RESULTS

A total of 42 individuals with human immunodeficiency virus (HIV) infection and 10 age-matched, uninfected control subjects were examined. Before HAART, IL-7 levels were increased and CD127 expression was decreased. Down-regulation of CD127 was mainly associated with T cell activation and reverted only partially after suppression of detectable plasma HIV RNA with HAART. In a multivariate analysis, CD127 expression on CD8(+) T cells was the main determinant of the extent of CD4(+) cell gains after successful HAART.

CONCLUSIONS

The IL-7-CD127 system is impaired in HIV-infected patients. CD127 down-regulation is associated with T cell activation and with CD4(+) cell restoration after HAART.

Residual viraemia in HIV-1-infected patients with plasma viral load <or=20 copies/ml is associated with increased blood levels of soluble immune activation markers

Despite undetectable viral load in conventional assays, probably all human immunodeficiency virus (HIV)-1 infected patients have residual viraemia (RV) detectable by ultra-sensitive assays. To study this issue, this study investigated virologic and immunologic consequences of RV in highly active antiretroviral therapy (HAART)-treated HIV-1-infected patients with plasma HIV-1 RNA <or=20 copies/ml. The study included 32 HAART-treated HIV-1-infected patients with HIV-1 RNA <or=20 copies/ml followed prospectively 6-monthly for 24 months. RV was detected by transcription-mediated amplification (TMA-RV) technique (Procleix HIV-1 Discriminatory Assay; Chiron) and by PCR (PCR-RV, Amplicor HIV-1 Monitor Assay; Roche Diagnostics). The association between RV and proviral-HIV-1-DNA, CD4-count, CD8-count, soluble [soluble tumour necrosis factor receptor (TNFr)-II, beta(2)-microglobulin, immunoglobulins] and cellular (HLA-DR, CD38, CD45RO, CD45RA, CD62L) T-cell markers of immune activation was investigated. In the 24-months study-period, 23 patients had >or=1 episode with TMA-RV whereas 9 patients had undetectable TMA-RV throughout the study-period. Time-points with TMA-RV and PCR-RV were associated with higher circulating sTNFrII (+0.234 ng/ml, P = 0.030) and beta(2)-microglobulin (+22 nmol/l, P = 0.016) and time-points with PCR-RV were also associated with higher IgA (+0.82 micromol/l, P = 0.035) and CD8-count (+1.18-fold, P = 0.001). Patients with TMA-RV in the study-period had higher HIV-1 RNA pre-HAART (P = 0.032). RV was not associated with proviral-HIV-1-DNA, CD4-count, CD4+HLA-DR+, CD8+HLA-DR+CD38+, CD4+CD45RA-CD45RO+, CD8+CD45RA-CD45RO+, CD4+CD45RA+CD62L+, CD8+CD45RA+CD62L+ T cells, IgG or IgM. In conclusion, RV was associated with increased blood levels of soluble immune activation markers in HAART-treated HIV-1-infected patients. The finding that RV was associated with higher pre-HAART plasma viral load suggests that RV is linked to pre-HAART disease progression.

Microbial translocation is associated with sustained failure in CD4+ T-cell reconstitution in HIV-infected patients on long-term highly active antiretroviral therapy

Patients with inefficient CD4+ T-cell recovery on virogically suppressive highly active antiretroviral therapy constitute a major clinical hurdle given the threat of HIV/AIDS disease progression. We show heightened circulating lipopolysaccharide associated with plasma enterobacterial DNA and highly activated Ki67+CD4+CD8+ in 24 immunologic-nonresponders (CD4+ T-cell < or = 200; HIV-RNA < or = 50) compared with 11 full responders (CD4+ T-cell > or= 400; HIV-RNA < or = 50). These data provide novel insight into INRs pathogenesis, since they correlate augmented systemic translocation of microbial bioproducts with T-cell hyperactivation.

Low immune activation despite high levels of pathogenic human immunodeficiency virus type 1 results in long-term asymptomatic disease

Long-term asymptomatic human immunodeficiency virus (HIV)-infected individuals (LTA) usually have low viral load and low immune activation. To discern whether viral load or immune activation is dominant in determining progression to AIDS, we studied three exceptional LTA with high viral loads. HIV type 1 isolates from these LTA were as pathogenic as viruses from progressors in organ culture. Despite high viral loads, these LTA had low levels of proliferating and activated T cells compared to progressors, like other LTA. In contrast to those in progressors, HIV-specific CD4(+) T-cell responses in these LTA were maintained. Thus, low immune activation despite a high viral load preserved HIV-specific T-cell responses and resulted in a long-term asymptomatic phenotype.

Abnormal activation and cytokine spectra in lymph nodes of people chronically infected with HIV-1

There is growing recognition that HIV-1 infection leads to an activation of the immune system that includes perturbations of cytokine expression, redistribution of lymphocyte subpopulations, cell dysfunction, and cell death. Here, we explored the relationships between HIV-1 infection and immune activation in chronically HIV-1-infected human lymph nodes. In addition to CD4 T-cell depletion, we found increased effector T-cell frequencies associated with profound up-regulation of an activation marker CD38 in naive, central memory, and effector CD4(+) and CD8(+) T cells. Likewise, Fas death receptor (CD95) was more frequently detectable on T cells from HIV-1 nodes. Dendritic cell (DC) depletion was dramatic, with plasmacytoid DCs (PDCs) 40-fold and myeloid DCs (MDCs) 20-fold less frequent in HIV(+) nodes than in control nodes. Cytokine dysregulation was evident, with IL-2 and IL-15 as much as 2 or 3 logs greater in infected nodes than in control nodes. Thus, activated effector cells are inappropriately attracted and/or retained in lymphoid tissue in chronic HIV-1 infection. High-level cytokine expression in turn activates and retains more cells at these sites, leading to lymphadenopathy and massive bystander activation that characterizes HIV-1 infection. Strategies targeting these activation pathways may lead to new therapies.

Slow disease progression and robust therapy-mediated CD4+ T-cell recovery are associated with efficient thymopoiesis during HIV-1 infection

In chronic HIV infection, most untreated patients lose naive CD4+ and CD8+ T cells, whereas a minority preserve them despite persistent high viremia. Although antiretroviral therapy (ART)–mediated viral suppression generally results in a rise of naive and total CD4+ T cells, certain patients experience very little or no T-cell reconstitution. High peripheral T-cell activation has been linked to poor clinical outcomes, interfering with previous evaluations of thymic function in disease progression and therapy-mediated T-cell recovery. To circumvent this, we used the sj/βTREC ratio, a robust index of thymopoiesis that is independent of peripheral T-cell proliferation, to evaluate the thymic contribution to the preservation and restoration of naive CD4+ T cells. We show that the loss of naive and total CD4+ T cells is the result of or is exacerbated by a sustained thymic defect, whereas efficient thymopoiesis supports naive and total CD4+ T-cell maintenance in slow progressor patients. In ART-treated patients, CD4+ T-cell recovery was associated with the normalization of thymopoiesis, whereas the thymic defect persisted in aviremic patients who failed to recover CD4+ T-cell counts. Overall, we demonstrate that efficient thymopoiesis is key in the natural maintenance and in therapy-mediated recovery of naive and total CD4+ T cells.

Elevated levels of activated CD4 T cells in common variable immunodeficiency: association with clinical findings

BACKGROUND

Common variable immunodeficiency (CVID) is a very heterogeneous syndrome defined by impaired immunoglobulin production. The primary defect remains unknown, but many reports describe peripheral blood T and B lymphocyte dysfunctions in a substantial proportion of CVID patients. Immunophenotypic alterations on memory B lymphocytes correlate with clinical findings. A B-cell-oriented classification principle of the patients has been proposed.

METHODS AND RESULTS

We investigated the expression of activation surface molecules on CD4 and CD8 T-cells from 14 patients with CVID, 6 non-CVID hypogammaglobulinemic patients with recurrent infections, 47 asymptomatic HIV-positive patients without AIDS defining conditions and 23 healthy subjects. Lymphocyte subsets were analysed by three-colour flow cytometry. Monoclonal panel: CD38-FITC/HLADR-PE/CD4 or CD8-PerCP. In CVID patients serum levels of CD4 T-cells co-expressing the activation marker HLA-DR [CD4+DR+ (34 %), CD4+CD38+DR+ (18 %)] were significantly elevated compared with controls. Significant increases in CD8+DR+ (54%), CD8+ CD38+ (43%) and CD8+CD38+DR+ (29%) T-cells were observed in comparison with healthy controls. CVID patients with splenomegaly, lower pre-infusion IgG levels (< 600 mg/dl), autoimmune or lymphoproliferative conditions demonstrated even higher levels of CD4+CD38+DR+T cells (22, 22, 21 and 21% respectively) compared with other CVID patients (13, 13, 15 and 15% respectively).

CONCLUSION

These findings indicate a state of ongoing T lymphocyte activation which is associated with clinical findings frequently observed in CVID.

[Immunophenotype of progression to AIDS: deficiency, activation and dysfunction of CD4 and CD8 T-cells]

INTRODUCTION

One key piece of information required when deciding whether to initiate antiretroviral therapy is the risk of AIDS. The aim of this study was to better characterize the baseline immunophenotypic profile of patients with progression to AIDS.

MATERIAL AND METHODS

A cross-sectional analysis of the distribution of functional subpopulations of CD4+ and CD8+ T-lymphocytes in 85 intravenous drug addicts with HIV infection. The values observed on patient enrolment in a prospective study were analyzed. Those patients who progressed and did not progress were compared to the HIV-negative controls. Lymphocyte subpopulations were studied by flow cytometry, including the markers: CD3, CD4, CD7, CD8, CD45RO, CD38, HLA-DR and CD25.

RESULTS

The immunophenotypic profile that precedes progression to AIDS was mainly characterized by an increase in memory (CD45RO) activated cells and total activated CD4+ and CD8+ cells, and by an increase of T CD4+ cells that have loss expression of markers as receptor or the differentiation marker CD7 (CD7-). Patients not meeting laboratory criteria to initiate antiretroviral therapy (> 350 CD4+ T-cells and < 30,000 HIV-ARN-copies/ml) also showed increased levels of CD4+ and CD8+ activation subsets (CD4+CD38+DR+, CD8+CD38+).

DISCUSSION

The fact that immunological activation may contribute to immunological and clinical deterioration of HIV-positive patients might be an additional factor which should be taken into account when deciding whether to initiate antiretroviral therapy.

The independent effect of drug resistance on T cell activation in HIV infection

OBJECTIVE

Antiretroviral-treated individuals with drug-resistant HIV experience slower CD4 cell count declines than untreated individuals, independent of degree of viremia. As immune activation independently predicts disease progression, we hypothesized that patients with drug-resistant viremia would have less immune activation than patients with wild-type viremia, independent of plasma HIV RNA levels and that these differences would not be explained by a direct drug effect of protease inhibitors.

METHODS

Percentages of activated (CD38/HLA-DR) T cells were compared between untreated participants with wild-type viremia and antiretroviral-treated participants with drug-resistant viremia, after adjusting for plasma HIV RNA levels among other factors associated with T cell activation. Changes in T cell activation were also assessed in subjects discontinuing protease inhibitors while continuing other antiretroviral medications.

RESULTS

Twenty-one untreated participants with wild-type viremia and 70 antiretroviral-treated participants with drug-resistant viremia were evaluated. Relative to untreated participants, those with drug-resistant viremia had 29% fewer activated CD4 (P = 0.051) and CD8 (P = 0.012) T cells after adjustment for plasma HIV RNA levels among other factors. There was no evidence for an early change in T cell activation among 13 subjects with drug-resistant viremia interrupting protease inhibitors while continuing other antiretroviral medications, but a significant increase in T cell activation with complete or partial emergence of wild-type sequences in protease.

CONCLUSIONS

Antiretroviral-treated patients with drug-resistant viremia have less T cell activation than untreated patients, independent of plasma HIV RNA level. Decreased ability of drug-resistant variants to cause T cell activation likely contributes to slower CD4 cell count declines among patients with drug-resistant viremia.

Immune reconstitution and predictors of virologic failure in adolescents infected through risk behaviors and initiating HAART: week 60 results from the PACTG 381 cohort

The responses to HAART in HIV-infected adolescents infected through risk behaviors are not well defined. PACTG 381 collected intensive immunologic and virologic data on youth naive to or with minimal exposure to antiretroviral therapy who began HAART. Subjects were evaluated according to their weeks 16-24 virologic response. Comparisons with a cohort of HIV-uninfected adolescents from the REACH cohort were performed. Cox proportional hazards models were used to identify baseline and week 24 predictors of virologic failure. Only 69 of 120 subjects (58%) achieved virologic suppression by weeks 16-24, whereas 55 of 69 (80%) demonstrated control to week 60. Higher CD4+ naive T cells (CD4+/62L+/RA+: hazard ratio [HR], 2.13; p = 0.018), higher CD8+ activated T cells (CD8+/CD38+/DR+: HR, 1.40, p = 0.028 per 100 cells/mm3) and higher CD8+ naive T cells (CD8+/62L+/RA+: HR, 1.72; p = 0.005) at weeks 16-24 in subjects with early viral success were predictive of subsequent failure. By week 60, total CD4+ T cells remained significantly lower than in uninfected controls. Adolescents beginning HAART achieve moderate rates of viral suppression by weeks 16-24. In those who do achieve early virologic control, suppression to week 60 is high although total CD4+ T cells remain significantly lower than in uninfected controls. Several T cell markers were predictive of subsequent virologic failure in subjects achieving short-term success. Further study is warranted to determine whether these predictors provide any benefit to clinical management.

Increased association of CD38 with lipid rafts in T cells from patients with systemic lupus erythematosus and in activated normal T cells

In this study we have determined whether there is a relationship between CD38 expression on T cells, its distribution in different membrane microdomains, and T cell activation in SLE patients. The data show that CD38 expression is augmented in ex vivo CD3+, CD4+, CD8+, and CD25+ SLE T cells, which correlates with its increased insolubility in Brij 98 detergent, and its translocation into lipid rafts. Moreover, SLE T cells show an altered CD4:CD8 ratio, which is due to a decreased proportion of CD4+ T cells and a concomitant increase in the proportion of CD8+ T cells. These data are consistent with the increased CD38 expression and lipid raft formation, and the significant reduction in the CD4:CD8 ratio observed in mitogen-stimulated normal T cells as compared with that in ex vivo untouched normal T cells. Increased expression of CD38 in floating rafts from SLE T cells, or from activated normal T cells may modulate TCR signaling by providing or sequestering signaling molecules to the engaged TCR.

Relationship between CD38 expression on peripheral blood T-cells and monocytes, and response to antiretroviral therapy: A one-year longitudinal study of a cohort of chronically infected ART-naive HIV-1+ patients

BACKGROUND

HIV-1 infection has been associated with high expression of CD38 on peripheral blood (PB) CD8+ and CD4+ T-cells, which has been related with poor prognosis in untreated HIV-1+ patients. In turn, CD38 expression on PB monocytes from HIV-1+ individuals and its behavior after starting antiretroviral therapy (ART) have been poorly studied.

METHODS

CD38 expression on PB CD8+ and CD4+ T-lymphocytes and monocytes was prospectively analyzed in 30 ART-naive HIV-1+ patients, using a quantitative multiparameter flow cytometry approach. Patients were tested prior to therapy, and at weeks +2, +4, +8, +12, and +52 after ART.

RESULTS

Prior to ART, CD38 expression was significantly increased on PB CD8+ and CD4+ T-cells and monocytes; despite a significant decrease after ART, CD38 expression remained abnormally high on PB CD8+ T-cells and monocytes, even after one year of therapy, in the absence of detectable plasma viral load. The ART-induced early changes on CD38 expression by PB T-cells and monocytes differed among the cell subsets analyzed and patient groups, probably reflecting an interaction between the direct effects of therapy and a redistribution of the PB compartments of T-cells and monocytes. Hierarchical clustering analysis showed that the overall pattern of changes in CD38 expression observed early after starting ART was predictive of a better response to therapy, not only for PB CD8+ T-cells, but also for CD4+ T-cells and monocytes. Accordingly, those HIV-1+ patients, who experienced a more pronounced increase in CD38 expression on both PB CD4+ T-cells and monocytes after 2 weeks of ART, showed a more rapid viral clearance, which might reflect decreased HIV-1 replication in lymph nodes and other tissues, and a partial restoration of hematopoiesis.

CONCLUSIONS

Combined quantitative measurement of CD38 expression on PB monocytes, and CD8+ and CD4+ T-cells is a more useful tool for monitoring HIV-1+ patients under ART, rather than quantitation of CD38 expression on PB CD8+ T-lymphocytes alone.

Persistent anti-gag, -Nef, and -Rev IgM levels as markers of the impaired functions of CD4+ T-helper lymphocytes during SIVmac251 infection of cynomolgus macaques

This study analyzed the antigen-specific (Gag, Nef, Rev, and Tat) IgM, IgG, and IgA humoral responses during the first 200 days of SIVmac251 infection in cynomolgus macaques. These responses were tested for correlation with the CD4(+) T-cell-related hematologic parameters and viral load throughout the course of the study (acute and chronic infection, during and after antiretroviral therapy). Strong inverse correlations were observed between the percentage of CD4(+) T cells at almost every timepoint of the study and the levels of IgM (but not IgG and IgA) against Gag, Nef, and Rev (but not Tat) measured after, but not during, the primary peak of IgM response. Significant levels of persistent antigen-specific IgMs may reflect the prevalence of mature plasma cells that have not undergone immunoglobulin class switching, possibly due to defects in helper T-cell function. Strong correlations were observed between the preinfection CD4(+) T-cell count or CD4/CD8 ratio and the same parameters measured throughout the study, suggesting the importance of preinfection immune status as a determinant of disease progression. The negative correlations between the post-acute-phase IgM levels and the percentage of CD4(+) T cells at later times during the study suggest the potential prognostic value of this measurement.

[Prevalence of C77G polymorphism in exon 4 of the CD45 gene in the Spanish population]

BACKGROUND AND OBJECTIVE

A mutation (C77G) in exon 4 of the CD45 gene is the most common cause of CD45 abnormal splicing in European populations, which has been associated with an increased susceptibility to human immunodeficiency virus infection. We aimed to analyze the C77G frequency in the Spanish population.

PATIENTS AND METHOD

517 healthy donors. CD45RA and RO expression was determined in circulating T lymphocytes by flow cytometry. CD45 exon 4 sequencing was carried out in individuals with an abnormal coexpression of CD45 isoforms.

RESULTS

6/517 individuals presented CD45RA persistence on memory T cells; all of them were heterozygous for C77G mutation. The resulting allelic frequency was 0,58% (95% confidence interval, 0.23-1.32).

CONCLUSIONS

C77G is present in the Spanish population. Further studies to elucidate its clinical significance are needed.

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.

CD4+ t-cell depletion in hiv infection: Killed by friendly fire?

Recent studies have emphasized the role of a chronic, generalized activation of the immune system as a prominent cause of CD4+ T-cell depletion in HIV-infected patients. The HIV-induced immune activation is a strong predictor of disease progression in humans, and lack of immune activation is a key feature of nonpathogenic simian immunodeficiency virus (SIV) infection of natural hosts. The mechanisms by which immune activation induces CD4+ T-cell depletion are still incompletely understood, but likely involve changes in the complex dynamics of the naive, memory, and effector subsets of T cells. A better understanding of how HIV-induced immune activation leads to CD4+ T-cell depletion may provide new targets for immune-based interventions that could be used, in addition to standard antiretroviral therapy, to slow disease progression in HIV-infected individuals.

Enhanced HIV-specific immune responses in chronically HIV-infected patients receiving didanosine plus hydroxyurea

BACKGROUND

The role of hydroxyurea (HU) in the treatment of HIV infection remains controversial. HU potentiates didanosine (ddI) antiviral activity and might exert immunomodulatory effects.

PATIENTS AND METHODS

Immunologic parameters were examined in HIV-infected patients enrolled in a simplification trial in which ddI-HU was provided to subjects who had been on complete virus suppression under highly active antiretroviral therapy (HAART) for longer than 6 months. A total of 84 of these patients showed plasma viraemia repeatedly below 5000 HIV-RNA copies/ml, and were the main study population. A group of 22 patients who continued on HAART and another of 22 drug-naive HIV-positive individuals were taken as controls.

RESULTS

At 12 months, the levels of naive and memory T-cell subsets were similar in patients on ddI-HU and under HAART, whereas immune activation tended to be lower in the former group. The frequency of HIV-specific CD8+ T cells (CTL) directed against 125 peptides derived from Gag, Pol, Env, Nef and HIV regulatory proteins was similar among patients on ddI-HU and untreated controls, and significantly higher than in patients under HAART. This higher CTL response in patients on ddI-HU was seen even when considering only subjects with undetectable viral load. HIV-specific CD4+ T-cell responses were absent in almost all patients on HAART, whereas they were present in up to 19% of patients on ddI-HU.

CONCLUSION

Treatment with ddI-HU provides higher levels of HIV-specific CD8+ and CD4+ T-cell responses than standard triple drug regimens. Thus, hydroxyurea might exert a beneficial immunomodulatory effect in HIV infection.

The activation profile of tumour-associated reactive T-cells differs in the nodular and diffuse patterns of lymphocyte predominant Hodgkin's disease

AIMS

To compare the activation profile of T-cells in reactive lymphoid follicles with that of tumour-associated T-cells in lymphocyte predominant Hodgkin's disease (LPHD) with a nodular pattern (n = 21), LPHD with partial diffuse growth pattern (n = 11) and T-cell-rich large B-cell lymphoma (TCRLBCL, n = 8).

METHODS AND RESULTS

Reactive germinal centres showed sparse numbers of T-cells positive for CD134, a transient/early T-cell activation marker, and only scattered T-cells in the interfollicular areas positive for CD38, a marker of persistent activation. Lymphoid follicles showing progressive transformation of germinal centres (PTGC) had more numerous CD134+ T-cells which were negative for CD38. Tumour-associated T-cells in nodular LPHD were frequently positive for CD134 (15 of 16 cases, 94%), but negative or only focally positive for CD38 (three of 21 cases, 14%). LPHD with diffuse areas, however, showed increased CD38+ T-cells in the diffuse component in 10 of 11 (90%) cases, with CD134+ T-cells being more prominent in the nodular tumour component. TCRLBCL showed strong, uniform CD38 expression in T-cells and histiocytes in eight cases.

CONCLUSIONS

T-cells in nodular LPHD express markers of transient/early T-cell activation. By contrast, T-cells in the diffuse form of LPHD, similar to those in TCRLBCL, have an immunostaining profile consistent with persistent cellular activation. T-cell activation may precede or accompany histological progression in nodular LPHD and immunostaining for these markers, in small samples or in difficult cases, may be useful in highlighting those cases of LPHD undergoing histological progression.

Differences in HIV-2 plasma viral load and immune activation in HIV-1 and HIV-2 dually infected persons and those infected with HIV-2 only in Abidjan, Côte D'Ivoire

OBJECTIVE

To determine whether blood plasma levels of HIV-2 RNA viral loads and immune activation markers differ between persons infected with HIV-2 only and those dually infected with HIV-1 and HIV-2.

METHODS

Between September 1996 and February 2000, we collected, analyzed and compared levels of HIV-2 RNA in plasma and immune activation markers among 52 persons infected with HIV-2 alone and 75 with confirmed dual infection. We also compared viral load and immune activation in patients who were infected with HIV-1 only and those who were dually infected.

RESULTS

When we conducted a CD4 T-cell count-stratified multivariate analysis of HIV-2 viral load, controlling for difference in CD4 T-cell counts, age and sex: at < 200 x 10 CD4 T cells/l, HIV-2 viral load was 2.0 log10 copies/ml lower in dually infected patients than in HIV-2 only patients (P < 0.0001). At CD4 T-cell counts between 200 x 10 and 500 x 10/l, HIV-2 viral load was 0.3 log10 copies/ml lower in dually infected patients (P = 0.45). However, at CD4 T-cells counts > 500 x 10/l, HIV-2 viral load was 0.9 log10 copies/ml higher in dually infected patients (P < 0.0001). Dually infected persons with undetectable HIV-2 viral loads had significantly higher median levels of CD8 T cells expressing CD38 (P < 0.001) and HLA-DR (P = 0.01) than HIV-2 only infected patients.

CONCLUSION

These results suggest that in dual infection, the level of HIV-2 replication depends on the immune status of the patients, with HIV-1 out-replicating HIV-2 as disease progress.

CD38 expression on CD8 T lymphocytes as a marker of residual virus replication in chronically HIV-infected patients receiving antiretroviral therapy

The level of CD8+ CD38+ T lymphocytes in blood correlates with disease progression in HIV-infected individuals, independently of the CD4 count. Effective antiretroviral therapy reduces this lymphocyte subset in parallel with plasma viremia, although CD38 expression on CD8+ cells does not normalize completely in most subjects, and might reflect residual HIV replication. The expression of CD38 on CD8+ cells (as number of CD38 molecules per CD8+ cell) was measured quantitatively by flow cytometry in 200 individuals, of whom 170 were HIV positive and 30 were HIV-uninfected controls. Forty-six HIV-infected subjects were on antiretroviral therapy and had undetectable viral load. The remaining 124 HIV-positive persons were not on therapy and had detectable plasma viremia. The mean level of CD38 on CD8+ cells was higher in HIV-positive, untreated patients than in subjects on antiviral therapy and controls (5023, 2029, and 1978 molecules per CD8+ cell, respectively, p < 0.01). In HIV-positive, untreated subjects, the higher CD38 expression mainly occurred on CD45RO+ CD8+ cells. The level of CD38 strongly correlated with plasma HIV-RNA (r = 0.63, p < 0.001). The levels of CD38 on CD8+ cells declined steadily in HIV-positive subjects after beginning antiretroviral therapy. A few individuals presented viral blips whereas being on antiviral treatment, levels of CD38 on CD8+ cells increased transiently in parallel with episodes of viral replication. Levels of CD38 on CD8+ cells are increased in chronic HIV infection, and strongly correlate with plasma viremia. The slow decline of CD38 expression on CD8+ cells over time in subjects with undetectable plasma viremia while being on antiretroviral therapy suggests that CD38 expression on CD8+ cells could be used as a marker of residual virus replication.

Persistent immune activation in HIV-1 infection is associated with progression to AIDS

BACKGROUND

HIV-1 infection is characterized by chronic generalized CD8 and CD4 T cell hyperactivation, the biological effect of which is not understood.

OBJECTIVE

To study the relation between chronic immune activation and CD4 T cell depletion in HIV-1 infection.

DESIGN

Prospective cohort study among participants of the Amsterdam Cohort Studies on HIV-1 infection and AIDS who have a known seroconversion date (n = 102).

METHODS

CD4 and CD8 T cell activation marker expression was analysed by FACScan before and after seroconversion (1 and 5 years after seroconversion); T cell proliferation and T cell numbers were also measured. Cox proportional hazard analyses were used to study the predictive value of these parameters for progression to AIDS.

RESULTS

Preseroconversion low CD4 T cell numbers or elevated levels of CD4 T cell activation were associated with increased risk for development of AIDS after HIV-1 seroconversion. Progression to AIDS was associated with loss of both CD4 and CD8 naive T cells. The predictive value of CD8 T cell activation was confirmed and, in addition, in the course of infection low CD4 T cell counts and increasing proportions of dividing CD4 T cells, dividing CD8 T cells or elevated CD4 T cell activation marker expression became independent predictors of progression to AIDS.

CONCLUSIONS

Increased T cell activation has predictive value for HIV-1 disease progression even before seroconversion. These data support the hypothesis that persistent hyperactivation of the immune system may lead to erosion of the naive T cell pool and CD4 T cell depletion.