Lack of good correlation of serum CC-chemokine levels with human immunodeficiency virus-1 disease stage and response to treatment

CD8+ Lymphocytes from Healthy Blood Donors Secrete Antiviral Levels of Interferon-Alpha

The adaptive immune response to viral infections features the antigen-driven expansion of CD8+ T cells. These cells are widely recognized for their cytolytic activity that is mediated through the secretion of cytokines such as perforin and granzymes. Less appreciated is their ability to secrete soluble factors that restrict virus replication without killing the infected cells. In this study we measured the ability of primary anti-CD3/28-stimulated CD8+ T cells from healthy blood donors to secrete interferon-alpha. Supernatants collected from CD8+ T cell cultures were screened for their ability to suppress HIV-1 replication in vitro and their interferon-alpha concentrations were measured by ELISA. Interferon-alpha concentrations in the CD8+ T cell culture supernatants ranged from undetectable to 28.6 pg/mL. The anti-HIV-1 activity of the cell culture supernatants was observed to be dependent on the presence of interferon-alpha. Appreciable increases in the expression levels of type 1 interferon transcripts were observed following T cell receptor stimulation, suggesting that the secretion of interferon-alpha by CD8+ T cells is an antigen-driven response. In 42-plex cytokine assays, the cultures containing interferon-alpha were also found to contain elevated levels of GM-CSF, IL-10, IL-13, and TNF-alpha. Together, these results demonstrate that the secretion of anti-viral levels of interferon-alpha is a common function of CD8+ T cells. Furthermore, this CD8+ T cell function likely plays broader roles in health and disease.

Reduced CCR5 Expression and Immune Quiescence in Black South African HIV-1 Controllers

Unique Individuals who exhibit either suppressive HIV-1 control, or the ability to maintain low viral load set-points and preserve their CD4+ T cell counts for extended time periods in the absence of antiretroviral therapy, are broadly termed HIV-1 controllers. We assessed the extent to which black South African controllers (n=9), differ from uninfected healthy controls (HCs, n=22) in terms of lymphocyte and monocyte CCR5 expression (density and frequency of CCR5-expressing cells), immune activation as well as peripheral blood mononuclear cell (PBMC) mitogen-induced chemokine/cytokine production. In addition, relative CD4+ T cell CCR5 mRNA expression was assessed in a larger group of controllers (n=20) compared to HCs (n=10) and HIV-1 progressors (n=12). Despite controllers having significantly higher frequencies of activated CD4+ and CD8+ T cells (HLA-DR+) compared to HCs, CCR5 density was significantly lower in these T cell populations (P=0.039 and P=0.064, respectively). This lower CCR5 density was largely attributable to controllers with higher VLs (>400 RNA copies/ml). Significantly lower CD4+ T cell CCR5 density in controllers was maintained (P=0.036) when HCs (n=12) and controllers (n=9) were matched for age. CD4+ T cell CCR5 mRNA expression was significantly less in controllers compared to HCs (P=0.007) and progressors (P=0.002), whereas HCs and progressors were similar (P=0.223). The levels of soluble CD14 in plasma did not differ between controllers and HCs, suggesting no demonstrable monocyte activation. While controllers had lower monocyte CCR5 density compared to the HCs (P=0.02), significance was lost when groups were age-matched (P=0.804). However, when groups were matched for both CCR5 promoter haplotype and age (n=6 for both) reduced CCR5 density on monocytes in controllers relative to HCs was highly significant (P=0.009). Phytohemagglutinin-stimulated PBMCs from the controllers produced significantly less CCL3 (P=0.029), CCL4 (P=0.008) and IL-10 (P=0.028) compared to the HCs, which was largely attributable to the controllers with lower VLs (<400 RNA copies/ml). Our findings support a hypothesis of an inherent (genetic) predisposition to lower CCR5 expression in individuals who naturally control HIV-1, as has been suggested for Caucasian controllers, and thus, likely involves a mechanism shared between ethnically divergent population groups.

A Novel Sample Selection Approach to Aid the Identification of Factors That Correlate With the Control of HIV-1 Infection

Individuals infected with HIV display varying rates of viral control and disease progression, with a small percentage of individuals being able to spontaneously control infection in the absence of treatment. In attempting to define the correlates associated with natural protection against HIV, extreme heterogeneity in the datasets generated from systems methodologies can be further complicated by the inherent variability encountered at the population, individual, cellular and molecular levels. Furthermore, such studies have been limited by the paucity of well-characterised samples and linked epidemiological data, including duration of infection and clinical outcomes. To address this, we selected 10 volunteers who rapidly and persistently controlled HIV, and 10 volunteers each, from two control groups who failed to control (based on set point viral loads) from an acute and early HIV prospective cohort from East and Southern Africa. A propensity score matching approach was applied to control for the influence of five factors (age, risk group, virus subtype, gender, and country) known to influence disease progression on causal observations. Fifty-two plasma proteins were assessed at two timepoints in the 1st year of infection. We independently confirmed factors known to influence disease progression such as the B^*57 HLA Class I allele, and infecting virus Subtype. We demonstrated associations between circulating levels of MIP-1α and IL-17C, and the ability to control infection. IL-17C has not been described previously within the context of HIV control, making it an interesting target for future studies to understand HIV infection and transmission. An in-depth systems analysis is now underway to fully characterise host, viral and immunological factors contributing to control.

Macrophage Inflammatory Protein-3 Alpha (MIP-3α)/CCL20 in HIV-1-Infected Individuals

OBJECTIVE

Uncontrolled HIV infection progresses to the depletion of systemic and mucosal CD4 and AIDS. Early HIV infection may be associated with increases in the concentration of MIP-3α in the blood and gut fluids. MIP-3α/CCL20 is the only chemokine known to interact with CCR6 receptors which are expressed on immature dendritic cells and both effector and memory CD8⁺ and CD4⁺ T cells. The role and prognostic value of blood levels of MIP-3α in HIV-infected individuals has yet to be described.

METHODS

We determined the serum levels of MIP-3α, and IFN-γ, in 167 HIV-1-infected and 27 HIV-1-uninfected men participating in the Multicenter AIDS Cohort Study (MACS). The blood biomarkers were measured using enzyme-linked immunosorbent assays (ELISA) and the cell phenotypes using flow cytometry.

RESULTS

Median serum levels of MIP-3α in HIV-1-infected and uninfected men was significantly different (p<0.0001) and were 21.3 pg/mL and 6.4 pg/mL respectively. The HIV-1-infected men with CD4⁺ T cell count <200 cells/μL showed the highest median serum MIP-3α (23.1 pg/mL). Serum levels of MIP-3α in HIV-1 infected (n=167) were negatively correlated with absolute number of CD4⁺ T cell (p=0.01) and were positively correlated with CD38 molecules on CD8⁺ T cells (p=0.0002) and with serum levels of IFN-γ (0.006).

CONCLUSION

Serum levels of MIP-3α concomitantly increase with plasma levels of IFN-γ, CD38 expression on CD8⁺ T cells, and decreased of absolute CD4⁺ T cells in HIV-1-infected men. A higher blood level of MIP-3α may be representation of locally high level of MIP-3α and more recruitment of immature dendritic cell at site of infection. Involvement of CCR6/CCL20 axis and epithelial cells at the recto-colonel level may enhance sexual transmission of HIV-1 in MSM and may be useful as a prognostic marker in HIV-1-infection and AIDS.

Intensive lifestyle modification reduces Lp-PLA2 in dyslipidemic HIV/HAART patients

PURPOSE

Patients with dyslipidemia associated with HIV-1 infection and highly active antiretroviral therapy (HAART) have elevated levels of Lp-PLA2 and CCL5/regulated on activation, normal T-cell expressed and secreted (RANTES), which may increase the risk of cardiovascular disease.

PURPOSE

This study aimed to determine whether an intensive diet and exercise (D/E) program, independently or combined with fenofibrate or niacin, could reduce Lp-PLA2 or RANTES.

METHODS

Patients with hypertriglyceridemic HIV on stable HAART (n = 107) were randomized to one of five interventions: 1) usual care, 2) D/E with placebos, 3) D/E with fenofibrate and placebo, 4) D/E with niacin and placebo, or 5) D/E with fenofibrate and niacin for 24 wk. Lp-PLA2 and RANTES concentrations were measured in fasting plasma samples at baseline and postintervention. General linear models were used to compare Lp-PLA2 and RANTES levels between the five groups postintervention, controlling for baseline levels, age, body mass index, CD4 T-cell count, viral load, duration of infection, and HAART.

RESULTS

At baseline, fasting plasma Lp-PLA2 (388.5 ± 127.5 ng·mL) and RANTES (43.8 ± 25.5 ng·mL) levels were elevated when compared with healthy controls. Posttreatment Lp-PLA2 mass was lower in patients who received D/E only (323.0 ± 27.2 ng·mL), D/E plus fenofibrate (327.2 ± 25.9 ng·mL), and D/E plus niacin (311.1 ± 27.8 ng·mL) when compared with patients receiving usual care (402.2 ± 25.3 ng·mL). RANTES concentrations were not significantly affected by any intervention.

CONCLUSIONS

Elevated plasma Lp-PLA2 mass can be reduced by an intensive D/E program in patients with HIV/HAART-associated dyslipidemia. RANTES is elevated but is not reduced by lifestyle modification, fenofibrate, or niacin.

Circulating interleukin-6, soluble CD14, and other inflammation biomarker levels differ between obese and nonobese HIV-infected adults on antiretroviral therapy

Obesity and chronic, treated HIV infection are both associated with persistent systemic inflammation and a similar constellation of metabolic and cardiovascular diseases, but the combined effects of excess adiposity and HIV on circulating proinflammatory cytokines and other biomarkers previously shown to predict disease risk is not well described. We measured inflammation biomarker levels in 158 predominantly virologically suppressed adults on long-term antiretroviral therapy (ART) with a range of body mass index (BMI) values from normal to morbidly obese. We assessed the relationship between BMI and each biomarker using multivariable linear regression adjusted for age, sex, race, CD4(+) count, tobacco use, data source, protease inhibitor use, and routine nonsteroidal antiinflammatory drug (NSAID) or aspirin use. Among normal-weight (n=48) and overweight participants (n=41; BMI <30 kg/m(2)), incremental BMI increases were associated with significantly higher serum highly sensitive C-reactive protein (hsCRP; β=2.47, p=0.02) and tumor necrosis factor (TNF)-α receptor 1 levels (β=1.53, p=0.03), and significantly lower CD14 levels (β=0.84, p=0.01), but similar associations were not observed in the obese participants. Among the obese (n=69; BMI ≥30 kg/m(2)), however, higher serum levels of interleukin-6 (IL-6; β=1.30, p=0.02) and macrophage inflammatory protein-1α (β=1.77, p<0.01) were associated with higher BMI, a finding not observed among the nonobese. Among all participants, IL-6 and TNF-α receptor 1 levels were most closely associated with hsCRP (p<0.01). Further studies are needed to determine whether higher serum inflammation biomarker levels found in obese HIV-infected individuals on ART reflect an increased likelihood of adverse health outcomes, or if novel markers to estimate mortality and disease risk are needed in this population.

Mendelian randomization: potential use of genetics to enable causal inferences regarding HIV-associated biomarkers and outcomes

PURPOSE OF REVIEW

It is unknown whether biomarkers simply correlate with or are causal for HIV-associated outcomes. Mendelian randomization is a genetic epidemiologic approach used to disentangle causation from association. Here, we discuss the potential use of Mendelian randomization for differentiating whether biomarkers are correlating with or causal for HIV-associated outcomes.

RECENT FINDINGS

Mendelian randomization refers to the random allocation of alleles at the time of gamete formation. In observational epidemiology, this refers to the use of genetic variants to estimate a causal effect between a modifiable risk factor and an outcome of interest. A formal Mendelian randomization study using a genetic marker as a proxy for the biomarker has not been conducted in the HIV field. However, in the postgenomic era, this approach is being used increasingly. Examples are evidence for the causal role of BMI in blood pressure and noncausal role of C-reactive protein in coronary heart disease. We discuss the conceptual framework, uses, and limitations of Mendelian randomization in the context of HIV infection as well as specific biomarkers (IL-6, C-reactive protein) and genetic determinants (e.g., in CCR5, chemokine, and DARC genes) that associate with HIV-related outcomes.

SUMMARY

Making the distinction between correlation and causality has particular relevance when a biomarker (e.g., IL-6) is potentially modifiable, in which case a biomarker-guided targeted treatment strategy may be feasible. Although the tenets of Mendelian randomization rest on strong assumptions, and conducting a Mendelian randomization study in HIV infection presents many challenges, it may offer the potential to identify causal biomarkers for HIV-associated outcomes.

Kinetics of plasma cytokines and chemokines during primary HIV-1 infection and after analytical treatment interruption

BACKGROUND

There are strong theoretical arguments for initiating antiretroviral therapy (ART) during primary HIV-1 infection (PHI) to preserve HIV-1-specific T-cell responses and to decrease immune activation.

METHODS

We assessed the degree of immune activation during PHI and after analytical treatment interruption (ATI) in plasma samples from 22 subjects by measuring 13 cytokines/chemokines with the Luminex system. Subjects initiated quadruple ART at PHI (the QUEST cohort) and were classified as responders or nonresponders according to their HIV-1 viral load (VL) 6 months post-ATI.

RESULTS

During PHI, nonresponders had higher levels of HIV-1 RNA, interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-10 and eotaxin than responders (P</=0.05). A positive correlation was found between VL and IFN-alpha, TNF-alpha, IL-1beta, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, respectively. Post ATI, responders had higher levels of IFN-gamma, MIP-1beta and monocyte chemotactic protein (MCP)-1 than nonresponders, while nonresponders had higher levels of HIV-1 RNA, IL-15 and eotaxin. Cytokine/chemokine levels were higher during PHI than post-ATI.

CONCLUSIONS

High levels of immune activation during PHI are associated with a worse virological outcome post-ATI. In contrast, VL post-ATI is negatively correlated with IFN-gamma and chemokines. Therefore, the degree of immune activation during PHI is associated with both the VL at PHI and the viral set-point post-ART.

Host genetic influences on highly active antiretroviral therapy efficacy and AIDS-free survival

We studied the influence of AIDS restriction genes (ARGs) CCR5-Delta32, CCR2-64I, SDF1-3'A, IL10-5'A, CX3CR1-V249I, CX3CR1-T280M, and MDR1-C3435T and haplotypes of the CCR5 P1 promoter and RANTES variants -403A, In1.1C, 3'222C, and -28G among HIV-1 infected patients on highly active antiretroviral therapy (HAART) in the Multicenter AIDS Cohort Study (MACS) and the Multicenter Hemophilia Cohort Study (MHCS). Our results indicate that several ARGs also influence therapy efficacy (ie, the success in viral suppression) and subsequent progression to AIDS while on HAART. CCR5-Delta32 decreased time to viral suppression (<200 HIV RNA copies/mL, relative hazard [RH]=1.40; P=0.008) and was protective against AIDS (RH=0.11; P=or<0.0001), whereas the CCR5 P1 haplotype was associated with delayed viral suppression (RNA<50 copies/mL, odds ratio [OR]=0.65; P=0.03) and accelerated time to AIDS (RH=2.68; P=0.02). SDF1-3'A reduced viral suppression (OR=0.61; P=0.02) and accelerated AIDS (RH=3.18; P=0.009). Accelerated AIDS progression was also observed with the RANTES haplotype carrying RANTES-IN1.1C and RANTES-3'222C (P=0.005 to 0.007). In contrast, the RANTES haplotype H1, which lacks suspected deleterious single-nucleotide polymorphisms, was protective against AIDS. CX3CR1-V249I seemed to accelerate viral suppression (RNA<50 copies/mL, OR=1.27; P=0.01). ARG influence after HAART suggests residual HIV-1 replication, and spread continues even in patients successfully suppressing detectable viral RNA.

Chemokine responses are increased in HIV-infected Malawian children with invasive pneumococcal disease

BACKGROUND

Chemokines play an important role in the recruitment and regulation of leukocyte traffic during bacterial infection. The aims of this study were to investigate the chemokine response to invasive pneumococcal disease (IPD) and to examine the influence of HIV infection on the chemokine response, pneumococcal bacterial loads, and outcome.

METHODS

We prospectively studied 95 children with IPD, and blood and cerebrospinal fluid (CSF) samples were taken at admission for the determination of chemokines, interferon-gamma (IFNgamma), and pneumococcal bacterial loads.

RESULTS

Plasma CXCL8 and CCL2, CSF CXCL8 and CCL4, and IFNgamma were significantly higher in HIV-infected children than in HIV-uninfected children. Blood and CSF pneumococcal bacterial loads correlated with plasma and CSF chemokines, respectively, and were higher in HIV-infected children compared with HIV-uninfected children. Among HIV-infected children, plasma concentrations of CXCL8 and CCL2 were significantly higher in nonsurvivors than in survivors, but CCL5 was significantly lower. HIV-infected and HIV-uninfected children with IPD had higher concentrations of chemokines (except CCL5) than acutely ill HIV-infected and HIV-uninfected children with no detectable bacterial infection. Male gender and low plasma CCL2 concentrations were shown to be independently associated with survival.

CONCLUSIONS

Chemokines, in particular CCL2, are associated with survival in IPD and correlate with pneumococcal bacterial loads, disease presentation, and outcome.

Influence of RANTES, SDF-1 and TGF-beta levels on the value of interleukin-7 as a predictor of virological response in HIV-1-infected patients receiving double boosted protease inhibitor-based therapy

OBJECTIVES

Interleukin-7 (IL-7), RANTES (regulated on activation, normal T cell expressed and secreted), stromal cell-derived factor-1 (SDF-1) and transforming growth factor-beta (TGF-beta) appear to share certain biological properties in vitro and all are involved in HIV-1 disease progression. Our earlier observations indicated that IL-7 levels decrease upon CD4 T-cell recovery and represent a new, independent predictor of virological response. Here, we examine associations among circulating levels of IL-7, RANTES, SDF-1 and TGF-beta in hopes of gaining insight into their contribution to the predictive value of IL-7.

METHODS

Levels of IL-7, RANTES, SDF-1 and TGF-beta, and immune and viral parameters were assessed in HIV-1-infected patients.

RESULTS

Cross-sectional (n=148) and longitudinal (n=36) analyses showed that levels of IL-7, but not RANTES, SDF-1 or TGF-beta, were increased in HIV-1-infected adults compared with those of healthy controls. In the cross-sectional study, levels of IL-7 were correlated with RANTES (r=0.31, P=0.002) and TGF-beta (r=0.53, P<0.001) but not with SDF-1 (r=0.12, P=0.22), and these associations were more pronounced in patients with CD4 T-cell counts >200 cells/microL. In contrast to IL-7, levels of RANTES, SDF-1 and TGF-beta were not correlated with CD4 T-cell counts. Longitudinal analysis revealed a marked decline in IL-7 levels accompanied by an increase in CD4 T-cell count following antiretroviral therapy (ART), but no changes in RANTES, SDF-1 or TGF-beta levels. Multivariate regression analysis showed no influence of baseline RANTES, SDF-1 or TGF-beta levels on the value of IL-7 as a predictor of virological response at 48 weeks.

CONCLUSIONS

Collectively, these results indicate that changes in IL-7 levels did not induce changes in RANTES, SDF-1 or TGF-beta. Furthermore, they indicate that RANTES, SDF-1 or TGF-beta levels do not explain the predictor value of IL-7 in patients receiving ART.