Helminth-Associated Systemic Immune Activation and HIV Co-receptor Expression: Response to Albendazole/Praziquantel Treatment

Background: It has been hypothesized that helminth infections increase HIV susceptibility by enhancing systemic immune activation and hence contribute to elevated HIV-1 transmission in sub-Saharan Africa. Objective: To study systemic immune activation and HIV-1 co-receptor expression in relation to different helminth infections and in response to helminth treatment. Methods: HIV-negative adults with (n = 189) or without (n = 57) different helminth infections, as diagnosed by Kato-Katz, were enrolled in Mbeya, Tanzania. Blinded to helminth infection status, T cell differentiation (CD45RO, CD27),activation (HLA-DR, CD38) and CCR5 expression was determined at baseline and 3 months after Albendazole/Praziquantel treatment. Plasma cytokine levels were compared using a cytometric bead array. Results: Trichuris and Ascaris infections were linked to increased frequencies of "activated'' CD4 and/or CD8 T cells (p< 0.05),whereas Hookworm infection was associated with a trend towards decreased HLA-DR+ CD8 T cell frequencies (p = 0.222). In Trichuris infected subjects, there was a linear correlation between HLA-DR+ CD4 T cell frequencies and the cytokines IL-1 beta and IL-10 (p<0.05). Helminth treatment with Albendazole and Praziquantel significantly decreased eosinophilia for S. mansoni and Hookworm infections (p<0.005) but not for Trichuris infection and only moderately modulated T cell activation. CCR5 surface density on memory CD4 T cells was increased by 1.2-fold during Trichuris infection (p-value: 0.053) and reduced after treatment (p = 0.003). Conclusions: Increased expression of T cell activation markers was associated with Trichuris and Ascaris infections with relatively little effect of helminth treatment

Untersuchungen zur prospektiven Identifizierung asthmaauslösender Substanzen im Atemtrakt

Um die Gefährdung der menschlichen Lunge durch toxische Stoffe zu beurteilen, muss deren gesundheitsschädliches Potential in ein Klassifizierungssystem eingestuft werden. Es besteht daher ein zunehmender Bedarf an geeigneten Methoden zur prospektiven Identifizierung des allergenen Potentials chemischer Substanzen im Atemtrakt. Ziel dieser Arbeit ist es, durch den Aufbau eines alternativen Kurzeitmodells die Induktionsphase der Lungensensibilisierung an der Brown Norway Ratte zu untersuchen und dessen Eignung zur Identifizierung lungensensibilisierender Substanzen zu prüfen. Insbesondere Analysen von Lungenzellinfiltraten bezüglich Eosinophilie und Neutrophilie, die Bestimmung von Zytokinen in der Lavageflüssigkeit und intrazellulär mittels Multiplex-Analysen (IL-1α, MCP-1, TNF-α, IFN-γ, GM-CSF, IL-4) sowie die Bestimmung von Aktivierungsmarkern (CD45+, CD25+) auf Lymphozyten anhand verschiedener FACS-Analysen stehen im Mittelpunkt der Untersuchungen. Die Anwendung des Protokolls analog zum lokalen Lymphknotentest (LLNA) unter Verwendung der intratracheal applizierten Modellsubstanz Trimellithanhydrid (TMA) bestätigt eine Reaktion in den drainierenden Lymphknoten der Lunge, die durch eine Zunahme des Gewichts und der Zellzahl nachweisbar und zudem durchflusszytometrisch bestimmbar ist. Die zum viel diskutierten Einfluss der Applikationsroute auf die Lungensensibilisierung durchgeführten inhalativen Provokationsstudien zeigen eine signifikante Erhöhung des Atemwegwiderstandes nach intratrachealer Vorbehandlung. Vergleichsweise führt eine epikutane Induktion zu einer verstärkten Granulozyteninfiltration und Expression inflammatorischer Zytokine in der Lunge der Ratte. Diese Experimente belegen die vollständige Entwicklung einer substanzspezifischen Lungenobstruktion in der Provokationsphase nach insgesamt nur dreimaliger intratrachealer Substanzapplikation. Zudem ermöglicht dieses Modell, mechanistische Vorgänge von der Induktion bis zur Sensi

Expression of systemic T cell activation markers in relation to infection with different helminth species.

<p>The frequencies of HLA-DR⁺CD38⁻ and total HLA-DR⁺ (B) are shown on the y-axis for CD4 (left panels) and CD8 T cells (right panels). The worm infection status is indicated on the x-axis stratified into worm negative individuals or those infected with TT (<i>Trichuris trichiura</i>), SH (<i>Schistosoma haematobium</i>), SM (<i>Schistosoma mansoni</i>), AL (<i>Ascaris lumbricoides</i>) or HW (Hookworm). Statistical analysis was performed using Mann-Whitney test for comparing groups. Shown in (C) is a linear regression analysis between the frequency of HLA-DR⁺/CD38⁺ CD8 T cells and the worm egg counts (as measured by Kato-Katz method) within Trichuris (left panel) and <i>S. mansoni</i> (right panel) infected subjects.</p

WHIS study cohort.

<p>WHIS study cohort.</p

Expression of activation markers on CD4 and CD8 T cells in relation to chronic infection with different helminth species on HIV negative individuals.

<p>*P values for comparison between helminth infected and non-infected controls were calculated using the Mann-Whitney test.</p

CD25(+) FoxP3(+) Memory CD4 T Cells Are Frequent Targets of HIV Infection In Vivo

Interleukin 2 (IL-2) signaling through the IL-2 receptor alpha chain (CD25) facilitates HIV replication in vitro and facilitates homeostatic proliferation of CD25+ FoxP3+ CD4+ T cells. CD25+ FoxP3+ CD4+ T cells may therefore constitute a suitable subset for HIV infection and plasma virion production. CD25+ FoxP3+ CD4+ T cell frequencies, absolute numbers, and the expression of CCR5 and cell cycle marker Ki67 were studied in peripheral blood from HIV+ and HIV− study volunteers. Different memory CD4+ T cell subsets were then sorted for quantification of cell-associated HIV DNA and phylogenetic analyses of the highly variable EnvV1V3 region in comparison to plasma-derived virus sequences. In HIV+ subjects, 51% (median) of CD25+ FoxP3+ CD4+ T cells expressed the HIV coreceptor CCR5. Very high frequencies of Ki67+ cells were detected in CD25+ FoxP3+ memory CD4+ T cells (median, 27.6%) in comparison to CD25− FoxP3− memory CD4+ T cells (median, 4.1%; P < 0.0001). HIV DNA content was 15-fold higher in CD25+ FoxP3+ memory CD4+ T cells than in CD25− FoxP3− T cells (P = 0.003). EnvV1V3 sequences derived from CD25+ FoxP3+ memory CD4+ T cells did not preferentially cluster with plasma-derived sequences. Quasi-identical cell-plasma sequence pairs were rare, and their proportion decreased with the estimated HIV infection duration. These data suggest that specific cellular characteristics of CD25+ FoxP3+ memory CD4+ T cells might facilitate efficient HIV infection in vivo and passage of HIV DNA to cell progeny in the absence of active viral replication. The contribution of this cell population to plasma virion production remains unclear

A phase 1 trial extension to assess immunologic efficacy and safety of prime-boost vaccination with VXM01, an oral T cell vaccine against VEGFR2, in patients with advanced pancreatic cancer

VXM01 is a first-in-kind orally applied tumor vaccine based on live attenuated Salmonella typhi carrying an expression plasmid encoding VEGFR2, an antigen expressed on tumor vasculature and a stable and accessible target for anti-angiogenic intervention. A recent randomized, placebo-controlled, phase I dose-escalation trial in advanced pancreatic cancer patients demonstrated safety, immunogenicity and transient, T-cell response-related anti-angiogenic activity of four priming vaccinations applied within one week. We here evaluated whether monthly boost vaccinations are safe and can sustain increased frequencies of vaccine-specific T cells. Patients with advanced pancreatic cancer were randomly assigned at a ratio of 2:1 to priming with VXM01 followed by up to six monthly boost vaccinations, or placebo treatment. Vaccinations were applied orally at two alternative doses of either 10(6) colony-forming units (CFU) or 10(7) CFU, and concomitant treatment with standard-of-care gemcitabine during the priming phase, and any treatment thereafter, was allowed in the study. Immunomonitoring involved interferon-gamma (IFN gamma) ELIspot analysis with long overlapping peptides spanning the entire VEGFR2 sequence. A total of 26 patients were treated. Treatment-related adverse events preferentially associated with VXM01 were decreases in lymphocyte numbers in the blood, increased frequencies of neutrophils and diarrhea. Eight out of 16 patients who received at least one boosting vaccination responded with pronounced, i.e. at least 3-fold, increase in VEGFR2-specific T cell response over baseline levels. In the VXM01 vaccination group, VEGFR2-specific T cells peaked preferentially during the boosting phase with an average 4-fold increase over baseline levels. In conclusion, prime/boost vaccination with VXM01 was safe and immunogenic and increased vaccine specific T cell responses compared with placebo treatment