A Statistical Interaction between Circumsporozoite Protein-Specific T Cell and Antibody Responses and Risk of Clinical Malaria Episodes following Vaccination with RTS,S/AS01E

The candidate malaria vaccine RTS,S/AS01_E provides significant but partial protection from clinical malaria. On in vitro circumsporozoite protein (CSP) peptide stimulation and intra-cellular cytokine staining of whole blood taken from 407 5–17 month-old children in a phase IIb trial of RTS,S/AS01_E, we identified significantly increased frequencies of two CSP-specific CD4+ T cells phenotypes among RTS,S/AS01_E vaccinees (IFNγ-IL2+TNF− and IFNγ-IL2+TNF+ CD4+ T cells), and increased frequency of IFNγ-IL2-TNF+ CD4+ T cells after natural exposure. All these T cells phenotypes were individually associated with reductions in the risk of clinical malaria, but IFNγ-IL2-TNF+ CD4+ T cells independently predicted reduced risk of clinical malaria on multi-variable analysis (HR = 0.29, 95% confidence intervals 0.15–0.54, p<0.0005). Furthermore, there was a strongly significant synergistic interaction between CSP-specific IFNγ-IL2-TNF+ CD4+ T cells and anti-CSP antibodies in determining protection against clinical malaria (p = 0.002). Vaccination strategies that combine potent cellular and antibody responses may enhance protection against malaria.     

Correlation of memory T cell responses against TRAP with protection from clinical malaria, and CD4 CD25 high T cells with susceptibility in Kenyans

Background

Immunity to malaria develops naturally in endemic regions, but the protective immune mechanisms are poorly understood. Many vaccination strategies aim to induce T cells against diverse pre-erythrocytic antigens, but correlates of protection in the field have been limited. The objective of this study was to investigate cell-mediated immune correlates of protection in natural malaria. Memory T cells reactive against thrombospondin-related adhesive protein (TRAP) and circumsporozoite (CS) protein, major vaccine candidate antigens, were measured, as were frequencies of CD4⁺ CD25^high T cells, which may suppress immunity, and CD56⁺ NK cells and γδ T cells, which may be effectors or may modulate immunity.

Methodology and Principal Findings

112 healthy volunteers living in rural Kenya were entered in the study. Memory T cells reactive against TRAP and CS were measured using a cultured IFNγ ELISPOT approach, whilst CD4⁺ CD25^high T cells, CD56⁺ NK cells, and γδ T cells were measured by flow cytometry. We found that T cell responses against TRAP were established early in life (<5 years) in contrast to CS, and cultured ELISPOT memory T cell responses did not correlate with ex-vivo IFNγ ELISPOT effector responses. Data was examined for associations with risk of clinical malaria for a period of 300 days. Multivariate logistic analysis incorporating age and CS response showed that cultured memory T cell responses against TRAP were associated with a significantly reduced incidence of malaria (p = 0.028). This was not seen for CS responses. Higher numbers of CD4⁺ CD25^high T cells, potentially regulatory T cells, were associated with a significantly increased risk of clinical malaria (p = 0.039).

Conclusions

These data demonstrate a role for central memory T cells in natural malarial immunity and support current vaccination strategies aimed at inducing durable protective T cell responses against the TRAP antigen. They also suggest that CD4⁺ CD25^high T cells may negatively affect naturally acquired malarial immunity.     

Interferon-alpha administration enhances CD8+ T cell activation in HIV infection

Background

Type I interferons play important roles in innate immune defense. In HIV infection, type I interferons may delay disease progression by inhibiting viral replication while at the same time accelerating disease progression by contributing to chronic immune activation.

Methods

To investigate the effects of type I interferons in HIV-infection, we obtained cryopreserved peripheral blood mononuclear cell samples from 10 subjects who participated in AIDS Clinical Trials Group Study 5192, a trial investigating the activity of systemic administration of IFNα for twelve weeks to patients with untreated HIV infection. Using flow cytometry, we examined changes in cell cycle status and expression of activation antigens by circulating T cells and their maturation subsets before, during and after IFNα treatment.

Results

The proportion of CD38+HLA-DR+CD8+ T cells increased from a mean of 11.7% at baseline to 24.1% after twelve weeks of interferon treatment (p = 0.006). These frequencies dropped to an average of 20.1% six weeks after the end of treatment. In contrast to CD8+ T cells, the frequencies of activated CD4+ T cells did not change with administration of type I interferon (mean percentage of CD38+DR+ cells = 2.62% at baseline and 2.17% after 12 weeks of interferon therapy). As plasma HIV levels fell with interferon therapy, this was correlated with a “paradoxical” increase in CD8+ T cell activation (p<0.001).

Conclusion

Administration of type I interferon increased expression of the activation markers CD38 and HLA DR on CD8+ T cells but not on CD4+ T cells of HIV+ persons. These observations suggest that type I interferons may contribute to the high levels of CD8+ T cell activation that occur during HIV infection.     

Cytokine profiles in asthma families depend on age and phenotype

Background

Circulating cytokine patterns may be relevant for the diagnosis of asthma, for the discrimination of certain phenotypes, and prognostic factors for exacerbation of disease.

Methodology/Principal Findings

In this study we investigated serum samples from 944 individuals of 218 asthma-affected families by a multiplex, microsphere based system detecting at high sensitivity eleven asthma associated mediators: eotaxin (CCL11), granulocyte macrophage stimulating factor (GM-CSF), interferon gamma (IFNγ), interleukin-4 (IL-4), IL-5, IL-8, IL-10, IL-12 (p40), IL-13, IL-17 and tumor necrosis factor alpha (TNFα). Single cytokine levels were largely similar between asthmatic and healthy individuals when analysing asthma as single disease entity. Regulatory differences between parental and pediatric asthma were reflected by six of the eleven mediators analyzed (eotaxin, IL-4, IL-5, IL-10, IL-12, TNFα). IL-12 (p40) and IL-5 were the best predictor for extrinsic asthma in children with an increased odds ratio of 2.85 and 1.96 per log pg/ml increase (IL-12 (p40): 1.2–6.8, p = 0.019, and IL-5: 1.2–2.5, p = 0.025). Frequent asthma attacks in children are associated with elevated IL-5 serum levels (p = 0.013). Cytokine patterns seem to be individually balanced in both, healthy and diseased adults and children, with various cytokines correlating among each other (IL-17 and IFNγ (r_s = 0.67), IL-4 and IL-5 (r_s = 0.55), IFNγ and GM-CSF (r_s = 0.54)).

Conclusion/Significance

Our data support mainly an age- but also an asthma phenotype-dependent systemic immune regulation.     

Preterm labor and chorioamnionitis are associated with neonatal T cell activation

Background

Preterm parturition is characterized by innate immune activation and increased proinflammatory cytokine levels. This well established association leads us to hypothesize that preterm delivery is also associated with neonatal T lymphocyte activation and maturation.

Methodology/Principal Findings

Cord blood samples were obtained following term, preterm, and deliveries complicated by clinical chorioamnionitis. Activation marker expression was quantitated by flow cytometric analysis. Infants born following preterm delivery demonstrated enhanced CD4⁺ T lymphocyte activation, as determined by CD25 (Term 9.72% vs. Preterm 17.67%, p = 0.0001), HLA-DR (Term 0.91% vs. Preterm 1.92%, p = 0.0012), and CD69 expression (Term 0.38% vs. Preterm 1.20%, p = 0.0003). Neonates delivered following clinical chorioamnionitis also demonstrated increased T cell activation. Preterm neonates had an increased frequency of CD45RO⁺ T cells.

Conclusion/Significance

Preterm parturition is associated with neonatal CD4⁺ T cell activation, and an increased frequency of CD45RO⁺ T cells. These findings support the concept that activation of the fetal adaptive immune system in utero is closely associated with preterm labor.     

T cell responses to the RTS,S/AS01(E) and RTS,S/AS02(D) malaria candidate vaccines administered according to different schedules to Ghanaian children

Background

The Plasmodium falciparum pre-erythrocytic stage candidate vaccine RTS,S is being developed for protection of young children against malaria in sub-Saharan Africa. RTS,S formulated with the liposome based adjuvant AS01_E or the oil-in-water based adjuvant AS02_D induces P. falciparum circumsporozoite (CSP) antigen-specific antibody and T cell responses which have been associated with protection in the experimental malaria challenge model in adults.

Methods

This study was designed to evaluate the safety and immunogenicity induced over a 19 month period by three vaccination schedules (0,1-, 0,1,2- and 0,1,7-month) of RTS,S/AS01_E and RTS,S/AS02_D in children aged 5–17 months in two research centers in Ghana. Control Rabies vaccine using the 0,1,2-month schedule was used in one of two study sites.

Results

Whole blood antigen stimulation followed by intra-cellular cytokine staining showed RTS,S/AS01_E induced CSP specific CD4 T cells producing IL-2, TNF-α, and IFN-γ. Higher T cell responses were induced by a 0,1,7-month immunization schedule as compared with a 0,1- or 0,1,2-month schedule. RTS,S/AS01_E induced higher CD4 T cell responses as compared to RTS,S/AS02_D when given on a 0,1,7-month schedule.

Conclusions

These findings support further Phase III evaluation of RTS,S/AS01_E. The role of immune effectors and immunization schedules on vaccine protection are currently under evaluation.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00360230","term_id":"NCT00360230"}}NCT00360230     

Cigarette smoke extract (CSE) delays NOD2 expression and affects NOD2/RIPK2 interactions in intestinal epithelial cells

Background

Genetic and environmental factors influence susceptibility to Crohn''s disease (CD): NOD2 is the strongest individual genetic determinant and smoking the best-characterised environmental factor. Carriage of NOD2 mutations predispose to small-intestinal, stricturing CD, a phenotype also associated with smoking. We hypothesised that cigarette smoke extract (CSE) altered NOD2 expression and function in intestinal epithelial cells.

Methods and Findings

Intestinal epithelial cell-lines (SW480, HT29, HCT116) were stimulated with CSE and nicotine (to mimic smoking) ±TNFα (to mimic inflammation). NOD2 expression was measured by qRT-PCR and western blotting; NOD2-RIPK2 interactions by co-immunoprecipitation (CoIP); nuclear NFκB-p65 by ELISA; NFκB activity by luciferase reporter assays and chemokines (CCL20, IL8) in culture supernatants by ELISA. In SW480 and HT29 cells the TNFα-induced NOD2 expression at 4 hours was reduced by CSE (p = 0.0226), a response that was dose-dependent (p = 0.003) and time-dependent (p = 0.0004). Similar effects of CSE on NOD2 expression were seen in cultured ileal biopsies from healthy individuals. In SW480 cells CSE reduced TNFα-induced NFκB-p65 translocation at 15 minutes post-stimulation, upstream of NOD2. Levels of the NOD2-RIPK2 complex were no different at 8 hours post-stimulation with combinations of CSE, nicotine and TNFα, but at 18 hours it was increased in cells stimulated with TNFα+CSE but decreased with TNFα alone (p = 0.0330); CSE reduced TNFα-induced NFκB activity (p = 0.0014) at the same time-point. At 24 hours, basal CCL20 and IL8 (p<0.001 for both) and TNFα-induced CCL20 (p = 0.0330) production were decreased by CSE. CSE also reduced NOD2 expression, CCL20 and IL8 production seen with MDP-stimulation of SW480 cells pre-treated with combinations of TNFα and CSE.

Conclusions

CSE delayed TNFα-induced NOD2 mRNA expression and was associated with abnormal NOD2/RIPK2 interaction, reduced NFκB activity and decreased chemokine production. These effects may be involved in the pathogenesis of small-intestinal CD and may have wider implications for the effects of smoking in NOD2-mediated responses.     

TIA-1 cytotoxic granule-associated RNA binding protein improves the prognostic performance of CD8 in mismatch repair-proficient colorectal cancer

Background

Evidence suggests a confounding effect of mismatch repair (MMR) status on immune response in colorectal cancer. The identification of innate and adaptive immune cells, that can complement the established prognostic effect of CD8 in MMR-proficient colorectal cancers patients, representing 85% of all cases, has not been performed.

Methodology/Principal Findings

Colorectal cancers from a test (n = 1197) and external validation (n = 209) cohort of MMR-proficient colorectal cancers were mounted onto single and multiple punch tissue microarrays. Immunohistochemical quantification (score 0-3) was performed for CD3, CD4, CD8, CD45RO, CD68, CD163, FoxP3, GranzymeB, iNOS, mast cell tryptase, MUM1, PD1 and TIA-1 tumor-infiltrating (TILs) reactive cells. Coexpression experiments on fresh colorectal cancer specimens using specific cell population markers were performed. In the test group, higher numbers of CD3+ (p<0.001), CD4+ (p = 0.029), CD8+ (p<0.001), CD45RO+ (p = 0.048), FoxP3+ (p<0.001), GranzymeB+ (p<0.001), iNOS+ (p = 0.035), MUM1+ (p = 0.014), PD1+ (p = 0.034) and TIA-1+ TILs (p<0.001) were linked to favourable outcome. Adjusting for age, gender, TNM stage and post-operative therapy, higher CD8+ (p<0.001; HR (95%CI): 0.66 (0.64-0.68)) and TIA-1+ (p<0.001; HR (95%CI): 0.56 (0.5-0.6)) were independent prognostic factors. Moreover, among patients with CD8+ infiltrates, TIA-1 further stratified 355 (35.6%) patients into prognostic subgroups (p<0.001; HR (95%CI): 0.89 (95%CI: 0.8-0.9)). Results were confirmed on the validation cohort (p = 0.006). TIA-1+ cells were mostly CD8+ (57%), but also stained for TCRγδ (22%), CD66b (13%) and only rarely for CD4+, macrophage and NK cell markers.

Conclusions

TIA-1 adds prognostic information to TNM stage and adjuvant therapy in MMR-proficient colorectal cancer patients. The prognostic effect of CD8+ TILs is confounded by the presence of TIA-1+ which translates into improved risk stratification for approximately 35% of all patients with MMR-proficient colorectal cancers.     

Coreceptor and cytokine concentrations may not explain differences in disease progression observed in HIV-1 clade A and D infected Ugandans

Background

The use of cellular coreceptors and modulation of cytokine concentrations by HIV to establish a productive infection is well documented. However, it is unknown whether the expression of these proteins affects the course of HIV clade A and D disease, reported to have different progression rates.

Methodology/Principal Findings

We investigated whether the number of CD4⁺ T-cells expressing CCR5 or CXCR4, the density of these coreceptors and concentrations of specific immune proteins linked to HIV pathogenesis vary between individuals infected with HIV clade A or D. We undertook additional analyses stratifying participants by early (CD4>500 cells/µl) or late (CD4<200 cells/µl) disease stage. Whole blood samples were taken from 50 HIV-1 infected individuals drawn from cohorts in rural south-west Uganda. Late stage participants had less than half the number of CD4⁺/CCR5⁺ T-cells (p = 0.0113) and 5.6 times fewer CD4⁺/CXCR4⁺ cells (p<0.0001) than early stage participants. There was also a statistically significant difference in the density of CXCR4 on CD4⁺ cells between clade A and D infected early stage participants (142 [A] vs 84 [D]; p = 0.0146). Across all participants we observed significantly higher concentration of Th₁ cytokines compared to Th₂ (66.4 vs 23.8 pg/ml; p<0.0001). Plasma concentrations of IFNγ and IL-2 were 1.8 and 2.4 fold lower respectively in Late-D infected participants compared to Late-A participants. MIP-1β levels also decreased from 118.0 pg/ml to 47.1 pg/ml (p = 0.0396) as HIV disease progressed.

Conclusions/Significance

We observed specific alterations in the abundance of CD4⁺/CCR5⁺ and CD4⁺/CXCR4⁺ T-cells, and concentrations of immune proteins across different HIV clades and as infection progresses. Our results suggest that these changes are unlikely to explain the observed differences in disease progression between subtype A and D infections. However, our observations further the understanding of the natural progression of non-clade B HIV infection and how the virus adapts to exploit the host environment.     

Safety, immunogenicity and duration of protection of the RTS,S/AS02(D) malaria vaccine: one year follow-up of a randomized controlled phase I/IIb trial

Background

The RTS,S/AS02_D vaccine has been shown to have a promising safety profile, to be immunogenic and to confer protection against malaria in children and infants.

Methods and Findings

We did a randomized, controlled, phase I/IIb trial of RTS,S/AS02_D given at 10, 14 and 18 weeks of age staggered with routine immunization vaccines in 214 Mozambican infants. The study was double-blind until the young child completed 6 months of follow-up over which period vaccine efficacy against new Plasmodium falciparum infections was estimated at 65.9% (95% CI 42.6–79.8, p<0.0001). We now report safety, immunogenicity and estimated efficacy against clinical malaria up to 14 months after study start. Vaccine efficacy was assessed using Cox regression models. The frequency of serious adverse events was 32.7% in the RTS,S/AS02_D and 31.8% in the control group. The geometric mean titers of anti-circumsporozoite antibodies declined from 199.9 to 7.3 EU/mL from one to 12 months post dose three of RTS,S/AS02_D, remaining 15-fold higher than in the control group. Vaccine efficacy against clinical malaria was 33% (95% CI: −4.3–56.9, p = 0.076) over 14 months of follow-up. The hazard rate of disease per 2-fold increase in anti-CS titters was reduced by 84% (95% CI 35.1–88.2, p = 0.003).

Conclusion

The RTS,S/AS02_D malaria vaccine administered to young infants has a good safety profile and remains efficacious over 14 months. A strong association between anti-CS antibodies and risk of clinical malaria has been described for the first time. The results also suggest a decrease of both anti-CS antibodies and vaccine efficacy over time.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00197028","term_id":"NCT00197028"}}NCT00197028     

FcγRIIIa expression on monocytes in rheumatoid arthritis: role in immune-complex stimulated TNF production and non-response to methotrexate therapy

Objective

The expression of FcγRIIIa/CD16 may render monocytes targets for activation by IgG-containing immune complexes (IC). We investigated whether FcγRIIIa/CD16 was upregulated in rheumatoid arthritis (RA), associated with TNF production in response to IC-stimulation, and if this predicted response to methotrexate therapy.

Methods

FcγRIIIa/CD16 expression on CD14^low and CD14⁺⁺ monocytes was measured by flow cytometry in healthy controls and RA patients (early and long-standing disease). Intracellular TNF-staining was carried out after in vitro LPS or heat-aggregated immunoglobulin (HAG) activation. FcγRIIIa/CD16 expression pre- and post-steroid/methotrexate treatment was examined.

Results

Increased FcγRIIIa/CD16 expression on CD14⁺⁺ monocytes in long-standing RA patients compared to controls was demonstrated (p = 0.002) with intermediate levels in early-RA patients. HAG-induced TNF-production in RA patients was correlated with the percentage of CD14⁺⁺ monocytes expressing FcγRIIIa/CD16 (p<0.001). The percentage of CD14⁺⁺ monocytes expressing FcγRIIIa/CD16 at baseline in early DMARD-naïve RA patients was negatively correlated with DAS28-ESR improvement 14-weeks post-methotrexate therapy (p = 0.003) and was significantly increased in EULAR non-responders compared to moderate (p = 0.01) or good responders (p = 0.003). FcγRIIIa/CD16 expression was not correlated with age, presence of systemic inflammation or autoantibody titers.

Conclusion

Increased FcγRIIIa/CD16 expression on CD14⁺⁺ monocytes in RA may result in a cell that has increased responsiveness to IC-stimulation. This monocyte subset may contribute to non-response to methotrexate therapy.     

Differential white blood cell count and type 2 diabetes: systematic review and meta-analysis of cross-sectional and prospective studies

Objective

Biological evidence suggests that inflammation might induce type 2 diabetes (T2D), and epidemiological studies have shown an association between higher white blood cell count (WBC) and T2D. However, the association has not been systematically investigated.

Research Design and Methods

Studies were identified through computer-based and manual searches. Previously unreported studies were sought through correspondence. 20 studies were identified (8,647 T2D cases and 85,040 non-cases). Estimates of the association of WBC with T2D were combined using random effects meta-analysis; sources of heterogeneity as well as presence of publication bias were explored.

Results

The combined relative risk (RR) comparing the top to bottom tertile of the WBC count was 1.61 (95% CI: 1.45; 1.79, p = 1.5*10⁻¹⁸). Substantial heterogeneity was present (I² = 83%). For granulocytes the RR was 1.38 (95% CI: 1.17; 1.64, p = 1.5*10⁻⁴), for lymphocytes 1.26 (95% CI: 1.02; 1.56, p = 0.029), and for monocytes 0.93 (95% CI: 0.68; 1.28, p = 0.67) comparing top to bottom tertile. In cross-sectional studies, RR was 1.74 (95% CI: 1.49; 2.02, p = 7.7*10⁻¹³), while in cohort studies it was 1.48 (95% CI: 1.22; 1.79, p = 7.7*10⁻⁵). We assessed the impact of confounding in EPIC-Norfolk study and found that the age and sex adjusted HR of 2.19 (95% CI: 1.74; 2.75) was attenuated to 1.82 (95% CI: 1.45; 2.29) after further accounting for smoking, T2D family history, physical activity, education, BMI and waist circumference.

Conclusions

A raised WBC is associated with higher risk of T2D. The presence of publication bias and failure to control for all potential confounders in all studies means the observed association is likely an overestimate.     

Intraepithelial γδ T cells remain increased in the duodenum of AIDS patients despite antiretroviral treatment

Intraepithelial lymphocytes (IELs) bearing the γδ T-cell receptor are a unique intestinal subset whose function remains elusive. Here, we examine how they behave in AIDS and during various regimens of antiretroviral treatment in order to obtain mechanistic insight into their adaptive or innate functional in vivo properties. IELs were studied by multimarker two-colour immunofluorescence in situ staining. Consecutive duodenal biopsies were obtained from advanced infection-prone HIV⁺ patients (n = 30). The systemic adaptive immune status was monitored by determining T-cell subsets and immunoglobulins in peripheral blood. The γδ IEL ratio (median 14.5%, range 1.5–56.3%) was significantly increased (p<0.02) compared with that in clinically healthy HIV⁻ control subjects (n = 11, median 2.8%; range 0.3–38%), although the number of γδ IELs per mucosal length unit (U) only tended to be increased (4.0/U in HIV⁺ versus 3.2/U in HIV⁻subjects). Notably, the total number of CD3⁺ IELs was significantly reduced in AIDS (p<0.0001, 39.6/U in HIV⁺ versus 86.4/U in HIV⁻ subjects). Almost 100% of the γδ IELs were CD8⁻ and they often expressed the Vδ1/Jδ1-encoded epitope (median 65.2%). HIV⁺ patients on highly active antiretroviral therapy only tended to have a lower ratio of γδ IELs (median 12.8%) than those receiving no treatment (median 14.3%) or 1 nucleoside analogue (NA) (median 23.5%) or 2 NAs (median 13.0%). This minimal variation among therapy groups, contrasting the treatment response of systemic and local adaptive immunity, harmonizes with the novel idea derived from animal experiments that γδ T cells are largely innate cells in first-line microbial defence.     

Age-related differences in naturally acquired T cell memory to Plasmodium falciparum merozoite surface protein 1

Naturally acquired immunity to Plasmodium falciparum malaria in malaria holoendemic areas is characterized by the gradual, age-related development of protection against high-density parasitemia and clinical malaria. Animal studies, and less commonly, observations of humans with malaria, suggest that T-cell responses are important in the development and maintenance of this immunity, which is mediated primarily by antibodies that slow repeated cycles of merozoites through erythrocytes. To advance our rather limited knowledge on human T-cell immunity to blood stage malaria infection, we evaluated CD4 and CD8 T-cell effector memory subset responses to the 42 kDa C-terminal fragment of Merozoite Surface Protein 1 (MSP1₄₂), a malaria vaccine candidate, by 49 healthy 0.5 to ≥18 year old residents of a holoendemic area in western Kenya. The proportion of individuals with peripheral blood mononuclear cell MSP1₄₂ driven IFN-γ ELISPOT responses increased from 20% (2/20) among 0.5–1 year old children to 90% (9/10) of adults ≥18 years (P = 0.01); parallel increases in the magnitude of IFN-γ responses were observed across all age groups (0.5, 1, 2, 5 and ≥18 years, P = 0.001). Less than 1% of total CD4 and CD8 T-cells from both children and adults produced IFN-γ in response to MSP1₄₂. However, adults had higher proportions of MSP1₄₂ driven IFN-γ secreting CD4 and CD8 effector memory (CD45RA⁻ CD62L⁻) T-cells than children (CD4: 50.9% vs. 28.8%, P = 0.036; CD8: 52.1% vs. 18.3%, respectively P = 0.009). In contrast, MSP1₄₂ driven IFN-γ secreting naïve-like, transitional (CD45RA⁺ CD62L⁺) CD4 and CD8 cells were the predominant T-cell subset among children with significantly fewer of these cells in adults (CD4: 34.9% vs. 5.1%, P = 0.002; CD8: 47.0% vs. 20.5%, respectively, P = 0.030). These data support the concept that meaningful age-related differences exist in the quality of T-cell immunity to malaria antigens such as MSP1.     

α1Proteinase inhibitor regulates CD4+ lymphocyte levels and is rate limiting in HIV-1 disease

Background

The regulation of adult stem cell migration through human hematopoietic tissue involves the chemokine CXCL12 (SDF-1) and its receptor CXCR4 (CD184). In addition, human leukocyte elastase (HLE) plays a key role. When HLE is located on the cell surface (HLE_CS), it acts not as a proteinase, but as a receptor for α₁proteinase inhibitor (α₁PI, α₁antitrypsin, SerpinA1). Binding of α₁PI to HLE_CS forms a motogenic complex. We previously demonstrated that α₁PI deficiency attends HIV-1 disease and that α₁PI augmentation produces increased numbers of immunocompetent circulating CD4⁺ lymphocytes. Herein we investigated the mechanism underlying the α₁PI deficiency that attends HIV-1 infection.

Methods and Findings

Active α₁PI in HIV-1 subjects (median 17 µM, n = 35) was significantly below normal (median 36 µM, p<0.001, n = 30). In HIV-1 uninfected subjects, CD4⁺ lymphocytes were correlated with the combined factors α₁PI, HLE_CS ⁺ lymphocytes, and CXCR4⁺ lymphocytes (r² = 0.91, p<0.001, n = 30), but not CXCL12. In contrast, in HIV-1 subjects with >220 CD4 cells/µl, CD4⁺ lymphocytes were correlated solely with active α₁PI (r² = 0.93, p<0.0001, n = 26). The monoclonal anti-HIV-1 gp120 antibody 3F5 present in HIV-1 patient blood is shown to bind and inactivate human α₁PI. Chimpanzee α₁PI differs from human α₁PI by a single amino acid within the 3F5-binding epitope. Unlike human α₁PI, chimpanzee α₁PI did not bind 3F5 or become depleted following HIV-1 challenge, consistent with the normal CD4⁺ lymphocyte levels and benign syndrome of HIV-1 infected chimpanzees. The presence of IgG-α₁PI immune complexes correlated with decreased CD4⁺ lymphocytes in HIV-1 subjects.

Conclusions

This report identifies an autoimmune component of HIV-1 disease that can be overcome therapeutically. Importantly, results identify an achievable vaccine modification with the novel objective to protect against AIDS as opposed to the current objective to protect against HIV-1 infection.     

Association of differentiation state of CD4+ T cells and disease progression in HIV-1 perinatally infected children

Background

In the USA, most HIV-1 infected children are on antiretroviral drug regimens, with many individuals surviving through adolescence and into adulthood. The course of HIV-1 infection in these children is variable, and understudied.

Methodology/Principal Findings

We determined whether qualitative differences in immune cell subsets could explain a slower disease course in long term survivors with no evidence of immune suppression (LTS-NS; CD4%≥25%) compared to those with severe immune suppression (LTS-SS; CD4%≤15%). Subjects in the LTS-NS group had significantly higher frequencies of naïve (CCR7+CD45RA+) and central memory (CCR7+CD45RA−) CD4+ T cells compared to LTS-SS subjects (p = 0.0005 and <0.0001, respectively). Subjects in the rapid progressing group had significantly higher levels of CD4+ T_EMRA (CCR7−CD45RA+) cells compared to slow progressing subjects (p<0.0001).

Conclusions/Significance

Rapid disease progression in vertical infection is associated with significantly higher levels of CD4+ T_EMRA (CCR7−CD45RA+) cells.     

Evaluation of RTS,S/AS02A and RTS,S/AS01B in Adults in a High Malaria Transmission Area

Background

This study advances the clinical development of the RTS,S/AS01B candidate malaria vaccine to malaria endemic populations. As a primary objective it compares the safety and reactogenicity of RTS,S/AS01B to the more extensively evaluated RTS,S/AS02A vaccine.

Methodology

A Phase IIb, single centre, double-blind, controlled trial of 6 months duration with a subsequent 6 month single-blind follow-up conducted in Kisumu West District, Kenya between August 2005 and August 2006. 255 healthy adults aged 18 to 35 years were randomized (1∶1∶1) to receive 3 doses of RTS,S/AS02A, RTS,S/AS01B or rabies vaccine (Rabipur®; Chiron Behring GmbH) at months 0, 1, 2. The primary objective was the occurrence of severe (grade 3) solicited or unsolicited general (i.e. systemic) adverse events (AEs) during 7 days follow up after each vaccination.

Principal Findings

Both candidate vaccines had a good safety profile and were well tolerated. One grade 3 systemic AE occurred within 7 days of vaccination (RTS,S/AS01B group). No unsolicited AEs or SAEs were related to vaccine. A marked increase in anti-CS antibody GMTs was observed post Dose 2 of both RTS,S/AS01B (31.6 EU/mL [95% CI: 23.9 to 41.6]) and RTS,S/AS02A (16.7 EU/mL [95% CI: 12.9 to 21.7]). A further increase was observed post Dose 3 in both the RTS,S/AS01B (41.4 EU/mL [95% CI: 31.7 to 54.2]) and RTS,S/AS02A (21.4 EU/mL [95% CI: 16.0 to 28.7]) groups. Anti-CS antibody GMTs were significantly greater with RTS,S/AS01B compared to RTS,S/AS02A at all time points post Dose 2 and Dose 3. Both candidate vaccines produced strong anti-HBs responses. Vaccine efficacy in the RTS,S/AS01B group was 29.5% (95% CI: −15.4 to 56.9, p = 0.164) and in the RTS,S/AS02A group 31.7% (95% CI: −11.6 to 58.2, p = 0.128).

Conclusions

Both candidate malaria vaccines were well tolerated over a 12 month surveillance period. A more favorable immunogenicity profile was observed with RTS,S/AS01B than with RTS,S/AS02A.

Trial Registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00197054","term_id":"NCT00197054"}}NCT00197054     

Tumor necrosis factor-alpha g308α gene polymorphism and essential hypertension: a meta-analysis involving 2244 participants

Background

The tumor necrosis factor-alpha (TNFα) G308A gene polymorphism has been implicated in susceptibility to essential hypertension (EH), but study results are still controversial.

Objective and Methods

The present meta-analysis is performed to investigate the relationship between the TNFα G308A gene polymorphism and EH. Electronic databases were searched and seven separate studies on the association of the TNF α G308A gene polymorphism with EH were analyzed. The meta-analysis involved 1092 EH patients and 1152 controls. The pooled odds ratios (ORs) and their corresponding 95% confidence interval (CI) were calculated by a fixed or random effect model.

Results

A significant relationship between the TNFα G308A gene polymorphism and EH was found in an allelic genetic model (OR: 1.45, 95% CI: 1.17 to 1.80, P = 0.0008), a recessive genetic model (OR: 3.181, 95% CI: 1.204 to 8.408, P = 0.02), and a homozygote model (OR: 3.454, 95% CI: 1.286 to 9.278, P = 0.014). No significant association between them was detected in both a dominant genetic model (OR: 1.55, 95% CI: 0.99 to 2.42, P = 0.06) or a heterozygote genetic model (OR: 1.45, 95% CI: 0.90 to 2.33, P = 0.13).

Conclusion

The TNFα G308A gene polymorphism is associated with EH susceptibility.