26 research outputs found
Inhibition of Plasmepsin V activity demonstrates its essential role in protein export, PfEMP1 display, and survival of malaria parasites
The malaria parasite Plasmodium falciparum exports several hundred proteins into the infected erythrocyte that are involved in cellular remodeling and severe virulence. The export mechanism involves the Plasmodium export element (PEXEL), which is a cleavage site for the parasite protease, Plasmepsin V (PMV). The PMV gene is refractory to deletion, suggesting it is essential, but definitive proof is lacking. Here, we generated a PEXEL-mimetic inhibitor that potently blocks the activity of PMV isolated from P. falciparum and Plasmodium vivax. Assessment of PMV activity in P. falciparum revealed PEXEL cleavage occurs cotranslationaly, similar to signal peptidase. Treatment of P. falciparum-infected erythrocytes with the inhibitor caused dose-dependent inhibition of PEXEL processing as well as protein export, including impaired display of the major virulence adhesin, PfEMP1, on the erythrocyte surface, and cytoadherence. The inhibitor killed parasites at the trophozoite stage and knockdown of PMV enhanced sensitivity to the inhibitor, while overexpression of PMV increased resistance. This provides the first direct evidence that PMV activity is essential for protein export in Plasmodium spp. and for parasite survival in human erythrocytes and validates PMV as an antimalarial drug target
CD81 and CD48 show different expression on blood eosinophils in systemic sclerosis: new markers for disease and pulmonary inflammation?
Criticality Analysis of Activity Networks under Interval Uncertainty
Dedicated to the memory of Professor Stefan Chanas - The extended abstract version of this paper has appeared in Proceedings of 11th International Conference on Principles and Practice of Constraint Programming (CP2005) ("Interval Analysis in Scheduling", Fortin et al. 2005)International audienceThis paper reconsiders the Project Evaluation and Review Technique (PERT) scheduling problem when information about task duration is incomplete. We model uncertainty on task durations by intervals. With this problem formulation, our goal is to assert possible and necessary criticality of the different tasks and to compute their possible earliest starting dates, latest starting dates, and floats. This paper combines various results and provides a complete solution to the problem. We present the complexity results of all considered subproblems and efficient algorithms to solve them
Consumption of pasteurized human lysozyme transgenic goatsâ milk alters serum metabolite profile in young pigs
Nutrition, bacterial composition of the gastrointestinal tract, and general health status can all influence the metabolic profile of an organism. We previously demonstrated that feeding pasteurized transgenic goatsâ milk expressing human lysozyme (hLZ) can positively impact intestinal morphology and modulate intestinal microbiota composition in young pigs. The objective of this study was to further examine the effect of consuming hLZ-containing milk on young pigs by profiling serum metabolites. Pigs were placed into two groups and fed a diet of solid food and either control (non-transgenic) goatsâ milk or milk from hLZ-transgenic goats for 6Â weeks. Serum samples were collected at the end of the feeding period and global metabolite profiling was performed. For a total of 225 metabolites (160 known, 65 unknown) semi-quantitative data was obtained. Levels of 18 known and 4 unknown metabolites differed significantly between the two groups with the direction of change in 13 of the 18 known metabolites being almost entirely congruent with improved health status, particularly in terms of the gastrointestinal tract health and immune response, with the effects of the other five being neutral or unknown. These results further support our hypothesis that consumption of hLZ-containing milk is beneficial to health
CD81 and CD48 show different expression on blood eosinophils in systemic sclerosis: new markers for disease and pulmonary inflammation?
In systemic sclerosis (SSc)-related interstitial lung disease (ILD), elevated eosinophil counts in bronchoalveolar lavage are associated with a worse outcome. We hypothesized that eosinophils may be activated in the peripheral circulation, thereby increasing their recruitment to affected tissues and contributing to inflammation and fibrosis. The aim of this study was to characterize the blood eosinophils in SSc patients
Transition State Mimetics of the Plasmodium Export Element Are Potent Inhibitors of Plasmepsin V from P. falciparum and P. vivax
Following
erythrocyte invasion, malaria parasites export a catalogue
of remodeling proteins into the infected cell that enable parasite
development in the human host. Export is dependent on the activity
of the aspartyl protease, plasmepsin V (PMV), which cleaves proteins
within the Plasmodium export element
(PEXEL; RxLâxE/Q/D) in the parasiteâs endoplasmic reticulum.
Here, we generated transition state mimetics of the native PEXEL substrate
that potently inhibit PMV isolated from Plasmodium
falciparum and Plasmodium vivax. Through optimization, we identified that the activity of the mimetics
was completely dependent on the presence of P<sub>1</sub> Leu and
P<sub>3</sub> Arg. Treatment of P. falciparum-infected erythrocytes with a set of optimized mimetics impaired
PEXEL processing and killed the parasites. The striking effect of
the compounds provides a clearer understanding of the accessibility
of the PMV active site and reaffirms the enzyme as an attractive target
for the design of future antimalarials
The Role of Selenium in Inflammation and Immunity: From Molecular Mechanisms to Therapeutic Opportunities
WEHI-916 is lethal to <i>P. falciparum</i> 3D7.
<p>(A) Dose-response curves of <i>P. falciparum</i> 3D7 in the presence of 916, 024, or 025. EC<sub>50</sub> values are shown. (B) Parasitemia measured at 72 h (<i>y</i>-axis) following drug treatment at rings (30 min postinvasion) and replacement of the medium with inhibitor-free medium (wash-out) at the time intervals shown (<i>x</i>-axis). (C) Parasitemia at 72 h (<i>y</i>-axis) after replacement of inhibitor-free medium with media containing compounds at the intervals shown (<i>x</i>-axis). Parasitemia was determined by FACS in (AâC) and is relative to DMSO treatment in (B) and (C). Concentrations are as follows: 916, 024, 025 (15 ”M); CQ, chloroquine (150 ng/ml); ART, artemisinin (100 ng/ml). Error bars in (AâC) are mean ±SEM from duplicate experiments. (D) Light micrographs of Giemsa-stained parasites 16 and 32 h after drug treatment at early rings (15 ”M). 916-treated parasites failed to develop into trophozoites and did not recover. Ring parasites treated with E-64 (10 ”M) <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001897#pbio.1001897-terKuile1" target="_blank">[22]</a> contained swollen food vacuoles (arrow) due to inhibition of proteases involved in hemoglobin degradation; however, treatment with DMSO, 916, 024, or 025 did not cause swelling. Swelling was quantified using 500 infected cells per condition in duplicate. Scale bar is 6 ”m.</p