Concentration and purification by magnetic separation of the erythrocytic stages of all human Plasmodium species

International audienceBackground : Parasite concentration methods facilitate molecular, biochemical and immunologicalresearch on the erythrocytic stages of Plasmodium. In this paper, an adaptation of magnetic MACS®columns for the purification of human Plasmodium species is presented. This method was useful forthe concentration/purification of either schizonts or gametocytes.Results and conclusions : The magnetic removal of non-parasitized red blood cells (in vivo andin vitro) using magnetic columns (MACS) was evaluated. This easy-to-use technique enrichedschizonts and gametocytes from Plasmodium falciparum in vitro cultures with a very high degree ofpurity. In addition, all haemozoin-containing stages (schizonts and/or gametocytes) from theperipheral blood of infected patients could be concentrated using this method. This method isparticularly useful for the concentration of non-falciparum species, which do not grow in cultureand are otherwise difficult to obtain in large amounts

New Microbicidal Functions of Tracheal Glands: Defective Anti-Infectious Response to Pseudomonas aeruginosa in Cystic Fibrosis

Tracheal glands (TG) may play a specific role in the pathogenesis of cystic fibrosis (CF), a disease due to mutations in the cftr gene and characterized by airway inflammation and Pseudomonas aeruginosa infection. We compared the gene expression of wild-type TG cells and TG cells with the cftr ΔF508 mutation (CF-TG cells) using microarrays covering the whole human genome. In the absence of infection, CF-TG cells constitutively exhibited an inflammatory signature, including genes that encode molecules such as IL-1α, IL-β, IL-32, TNFSF14, LIF, CXCL1 and PLAU. In response to P. aeruginosa, genes associated with IFN-γ response to infection (CXCL10, IL-24, IFNγR2) and other mediators of anti-infectious responses (CSF2, MMP1, MMP3, TLR2, S100 calcium-binding proteins A) were markedly up-regulated in wild-type TG cells. This microbicidal signature was silent in CF-TG cells. The deficiency of genes associated with IFN-γ response was accompanied by the defective membrane expression of IFNγR2 and altered response of CF-TG cells to exogenous IFN-γ. In addition, CF-TG cells were unable to secrete CXCL10, IL-24 and S100A8/S100A9 in response to P. aeruginosa. The differences between wild-type TG and CF-TG cells were due to the cftr mutation since gene expression was similar in wild-type TG cells and CF-TG cells transfected with a plasmid containing a functional cftr gene. Finally, we reported an altered sphingolipid metabolism in CF-TG cells, which may account for their inflammatory signature. This first comprehensive analysis of gene expression in TG cells proposes a protective role of wild-type TG against airborne pathogens and reveals an original program in which anti-infectious response was deficient in TG cells with a cftr mutation. This defective response may explain why host response does not contribute to protection against P. aeruginosa in CF

Influence of oxygen on asexual blood cycle and susceptibility of Plasmodium falciparum to chloroquine: requirement of a standardized in vitro assay

OBJECTIVE: The main objective of this study was to assess the influence of gas mixtures on in vitro Plasmodium falciparum growth and 50% inhibitory concentration (IC(50)) for chloroquine. METHODS: The study was performed between February 2004 and December 2005. 136 Plasmodium falciparum isolates were used to evaluate gas mixtures effect on IC(50 )for chloroquine by isotopic microtest. The oxygen effect on asexual blood cycle of 3D7 and W2 clones was determined by thin blood smears examination and tritiated hypoxanthine uptake. RESULTS: From 5% O(2 )to 21% O(2 )conditions, no parasiticide effect of O(2 )concentration was observed in vitro on the clones 3D7 and W2. A parasitostatic effect was observed during the exposure of mature trophozoïtes and schizonts at 21% O(2 )with an increase in the length of schizogony. The chloroquine IC(50 )at 10% O(2 )were significantly higher than those at 21% O(2), means of 173.5 nM and 121.5 nM respectively (p < 0.0001). In particular of interest, among the 63 isolates that were in vitro resistant to chloroquine (IC(50 )> 100 nM) at 10% O(2), 17 were sensitive to chloroquine (IC(50 )< 100 nM) at 21% O(2). CONCLUSION: Based on these results, laboratories should use the same gas mixture to realize isotopic microtest. Further studies on comparison of isotopic and non-isotopic assays are needed to establish a standardized in vitro assay protocol to survey malaria drug resistance

Polymorphism of Plasmodium falciparum Na+/H+ exchanger is indicative of a low in vitro quinine susceptibility in isolates from Viet Nam

<p>Abstract</p> <p>Background</p> <p>The <it>Plasmodium falciparum </it>NA+/H+ exchanger (<it>pfnhe1</it>, gene PF13_0019) has recently been proposed to influence quinine (QN) susceptibility. However, its contribution to QN resistance seems to vary geographically depending on the genetic background of the parasites. Here, the role of this gene was investigated in <it>in vitro </it>QN susceptibility of isolates from Viet Nam.</p> <p>Method</p> <p>Ninety-eight isolates were obtained from three different regions of the Binh Phuoc and Dak Nong bordering Cambodia provinces during 2006-2008. Among these, 79 were identified as monoclonal infection and were genotyped at the microsatellite <it>pfnhe1 </it>ms4760 locus and <it>in vitro </it>QN sensitivity data were obtained for 51 isolates. Parasite growth was assessed in the field using the HRP2 immunodetection assay.</p> <p>Results</p> <p>Significant associations were found between polymorphisms at <it>pfnhe1 </it>microsatellite ms4760 and susceptibility to QN. Isolates with two or more DNNND exhibited much lower susceptibility to QN than those harbouring zero or one DNNND repeats (median IC₅₀of 682 nM <it>versus </it>median IC₅₀of 300 nM; <it>p </it>= 0.0146) while isolates with one NHNDNHNNDDD repeat presented significantly reduced QN susceptibility than those who had two (median IC₅₀of 704 nM <it>versus </it>median IC₅₀of 375 nM; p < 0.01). These QNR associated genotype features were mainly due to the over representation of profile 7 among isolates (76.5%). The majority of parasites had <it>pfcrt76T </it>and wild-type <it>pfmdr1 </it>(> 95%) thus preventing analysis of associations with these mutations. Interestingly, area with the highest median QN IC₅₀showed also the highest percentage of isolates carrying the <it>pfnhe1 </it>haplotype 7.</p> <p>Conclusions</p> <p>The haplotype 7 which is the typical Asian profile is likely well-adapted to high drug pressure in this area and may constitute a good genetic marker to evaluate the dissemination of QNR in this part of the world.</p

Quinine-Resistant Malaria in Traveler Returning from Senegal, 2007

We describe clinical and parasitologic features of in vivo and in vitro Plasmodium falciparum resistance to quinine in a nonimmune traveler who returned to France from Senegal in 2007 with severe imported malaria. Clinical quinine failure was associated with a 50% inhibitory concentration of 829 nmol/L. Increased vigilance is required during treatment follow-up

Global response of Plasmodium falciparum to hyperoxia: a combined transcriptomic and proteomic approach

<p>Abstract</p> <p>Background</p> <p>Over its life cycle, the <it>Plasmodium falciparum </it>parasite is exposed to different environmental conditions, particularly to variations in O₂pressure. For example, the parasite circulates in human venous blood at 5% O₂pressure and in arterial blood, particularly in the lungs, at 13% O₂pressure. Moreover, the parasite is exposed to 21% O₂levels in the salivary glands of mosquitoes.</p> <p>Methods</p> <p>To study the metabolic adaptation of <it>P. falciparum </it>to different oxygen pressures during the intraerythrocytic cycle, a combined approach using transcriptomic and proteomic techniques was undertaken.</p> <p>Results</p> <p>Even though hyperoxia lengthens the parasitic cycle, significant transcriptional changes were detected in hyperoxic conditions in the late-ring stage. Using PS 6.0™ software (Ariadne Genomics) for microarray analysis, this study demonstrate up-expression of genes involved in antioxidant systems and down-expression of genes involved in the digestive vacuole metabolism and the glycolysis in favour of mitochondrial respiration. Proteomic analysis revealed increased levels of heat shock proteins, and decreased levels of glycolytic enzymes. Some of this regulation reflected post-transcriptional modifications during the hyperoxia response.</p> <p>Conclusions</p> <p>These results seem to indicate that hyperoxia activates antioxidant defence systems in parasites to preserve the integrity of its cellular structures. Moreover, environmental constraints seem to induce an energetic metabolism adaptation of <it>P. falciparum</it>. This study provides a better understanding of the adaptive capabilities of <it>P. falciparum </it>to environmental changes and may lead to the development of novel therapeutic targets.</p

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Protéine-kinases et ligands de surface (contribution à l'étude de la communication intra- et extra-cellulaire chez Plasmodium falciparum)

AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

CLONAGE, EXPRESSION ET PURIFICATION DU DOMAINE CATALYTIQUE DE DEUX PROTEINES KINASES DE PLASMODIUM FALCIPARUM (PFMAP-1 ET PFERK-1)

AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF

Transmission risk of canine ehrlichiosis to human beings

Alors qu’aux États-Unis, plus de 200 cas humains d’ehrlichiose à Ehrlichia canis diagnostiqués sérologiquement ont été rapportés depuis 1986, les auteurs ont démontré indirectement par des arguments épidémiologiques que l’homme n’était pas réceptif à cette rickettsiose. Ils ont effectué une étude séroépidémiologique qui montre que les personnes présentant des commémoratifs de morsures de Rhipicephalus et en contact étroit et prolongé avec des chiens infectés, n’ont pas de trace d’anticorps spécifiques d'E. canis. Depuis, en 1991, les auteurs états-uniens ont isolé l’agent pathogène responsable de l’ehriichiose humaine (E. chaffeensis).Although more than 200 cases of human ehrlichiosis due to Ehrlichia canis have been diagnosed since 1986 in the United States, the authors showed by epidemiological arguments that human beings are not receptive to this rickett- siosis. A seroepidemiological study was carried out and showed that people who were bitten by Rhipicephalus or who lived close to infected dogs were not reactive to the specific anti E. canis anti-body. The pathogenic agent of human ehrlichiosis (E. chaffeensis) has bee idendified by Americans authors since 1991