Complete Genome Sequence of Crohn's Disease-Associated Adherent-Invasive E. coli Strain LF82

International audienceBACKGROUND: Ileal lesions of Crohn's disease (CD) patients are abnormally colonized by pathogenic adherent-invasive Escherichia coli (AIEC) able to invade and to replicate within intestinal epithelial cells and macrophages. PRINCIPAL FINDINGS: We report here the complete genome sequence of E. coli LF82, the reference strain of adherent-invasive E. coli associated with ileal Crohn's disease. The LF82 genome of 4,881,487 bp total size contains a circular chromosome with a size of 4,773,108 bp and a plasmid of 108,379 bp. The analysis of predicted coding sequences (CDSs) within the LF82 flexible genome indicated that this genome is close to the avian pathogenic strain APEC_01, meningitis-associated strain S88 and urinary-isolated strain UTI89 with regards to flexible genome and single nucleotide polymorphisms in various virulence factors. Interestingly, we observed that strains LF82 and UTI89 adhered at a similar level to Intestine-407 cells and that like LF82, APEC_01 and UTI89 were highly invasive. However, A1EC strain LF82 had an intermediate killer phenotype compared to APEC-01 and UTI89 and the LF82 genome does not harbour most of specific virulence genes from ExPEC. LF82 genome has evolved from those of ExPEC B2 strains by the acquisition of Salmonella and Yersinia isolated or clustered genes or CDSs located on pLF82 plasmid and at various loci on the chromosome. CONCLUSION: LF82 genome analysis indicated that a number of genes, gene clusters and pathoadaptative mutations which have been acquired may play a role in virulence of AIEC strain LF82

Modulation fonctionnelle des polynucléaires neutrophiles par les Escherichia coli d adhésion diffuse (DAEC) exprimant les adhésines Afa/Dr

Les DAEC Afa/Dr sont responsables de diarrhées et d infections urinaires. In-vitro, ils provoquent la migration des polynucléaires neutrophiles (PN) à travers l épithélium intestinal. L objectif de notre travail a été d approfondir l étude de la modulation directe des fonctions et de la mort des PN induite par les DAEC Afa/Dr, grâce à l utilisation de la lignée cellulaire PLB-985 différenciée en PN. Dans un premier temps, nous démontrons que plusieurs souches de DAEC Afa/Dr induisent une réponse pro-inflammatoire importante, en particulier en provoquant une hyperproduction d IL-8. Dans un second temps, nous montrons que l adhésine F1845 induit l externalisation de la phosphatidylsérine (PS), cet effet passant par sa fixation sur son récepteur DAF. Cette externalisation de PS n est pas liée à l apoptose mais permet la phagocytose des PLB-985 infectées, participant ainsi à la résolution de l inflammation.Afa/Dr DAEC causing childhood diarrhea can induce, in-vitro, the migration of polymorphonuclear neutrophils (PMN) through the intestinal epithelium. Using the human PLB-985 cell line differentiated into fully mature PMN, we described the coordinated response to various E. coli. We show that several strains of Afa/Dr DAEC induced a significant pro-inflammatory response, particularly by causing an overproduction of IL-8. Then we show that F1845 adhesin induced externalization of phosphatidylserine (PS). This effect was triggered in part by DAF receptor engagement. Interestingly, although apoptosis pathways were not engaged, this PS externalization displayed enhanced removal by macrophages, a phenomenon possibly participating in the resolution of inflammation.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

”Cage” metal-organic nanoparticles: applications to treat infections

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Towards an Improved anti-HIV Activity of NRTI via Metal-Organic Frameworks Nanoparticles

Nanoscale mesoporous iron carboxylates metal-organic frameworks (nanoMOFs) have recently emerged as promising platforms for drug delivery, showing biodegradability, biocompatibility and important loading capability of challenging highly water-soluble drugs such as azidothymidine tryphosphate (AZT-TP). In this study, nanoMOFs made of iron trimesate (MIL-100) were able to act as efficient molecular sponges, quickly adsorbing up to 24 wt% AZT-TP with entrapment efficiencies close to 100%, without perturbation of the supramolecular crystalline organization. These data are in agreement with molecular modelling predictions, indicating maximal loadings of 33 wt% and preferential location of the drug in the large cages. Spectrophotometry, isothermal titration calorimetry, and solid state NMR investigations enable to gain insight on the mechanism of interaction of AZT and AZT-TP with the nanoMOFs, pointing out the crucial role of phosphates strongly coordinating with the unsaturated iron(III) sites. Finally, contrarily to the free AZT-TP, the loaded nanoparticles efficiently penetrate and release their cargo of active triphosphorylated AZT inside major HIV target cells, efficiently protecting against HIV infection

Combinatorial Drug Therapy: Compartmentalized Encapsulation of Two Antibiotics in Porous Nanoparticles: an Efficient Strategy to Treat Intracellular Infections (Part. Part. Syst. Charact. 3/2019)

International audienceBack Cover : As demonstrated by Ruxendra Gref and co‐workers in article number 1800360, two synergic drugs, amoxicillin and potassium clavulanate, were co‐encapsulated within highly porous nanoparticles made of metal‐organic frameworks (nanoMOFs). Within the interconnected 3D structure, each drug located in a separate compartment and these findings were supported by molecular simulations. NanoMOFs were efficiently internalized in infected macrophages and contributed together with the entrapped drugs to kill intracellular bacteria

Compartmentalized Encapsulation of Two Antibiotics in Porous Nanoparticles: an Efficient Strategy to Treat Intracellular Infections

International audienceCombinatorial drug therapies emerge among the most promising strategies to treat complex pathologies such as cancer and severe infections. Biocompatible nanoparticles of mesoporous iron carboxylate metal–organic framework (nanoMOFs) are used here to address the challenging aspects related to the coincorporation of two antibiotics. Amoxicillin and potassium clavulanate, a typical example of drugs used in tandem, are efficiently coincorporated with payloads up to 36 wt%. Due to the occurrence of two distinct pore sizes/apertures within the MOF architecture, each drug is able to infiltrate the porous framework and localize within separate compartments. Molecular simulations predict drug loadings and locations consistent with experimental findings. Drug loaded nanoMOFs that are internalized by Staphylococcus aureus infected macrophages are able to colocalize with the pathogen, which in turn leads to an alleviation of bacterial infection. The data also reveal potential antibacterial properties of nanoMOFs alone as well as their ability to deliver a high payload of drugs to fight intracellular bacteria. These results pave the way toward the design of engineered “all‐in‐one” nanocarriers in which both the loaded drugs and their carrier play a role in fighting intracellular infections

Interleukin-8 Gene Regulation in Epithelial Cells by Vibrio Cholerae: Role of Multiple Promoter Elements, Adherence and Motility of Bacteria and Host MAPKs

Interleukin (IL)-8 is an important mediator in neutrophil-mediated acute inflammation. We previously demonstrated that incubation of intestinal epithelial cells with Vibrio cholerae O395 resulted in increased IL-8 mRNA expression and IL-8 secretion, which was associated with the adherence and motility of bacteria. However, the mechanisms responsible for transcriptional regulation of the IL-8 gene in epithelial cells during V. cholerae infections were not explored. Transient transfection analysis of 5¢ deletions and mutations of the IL-8 promoter driving expression of the luciferase reporter gene indicates that multiple binding sites contribute to IL-8 promoter induction in response to V. cholerae and that cooperation among these different sites is required for full activation of the promoter. Stimulation with V. cholerae O395 insertional mutants, defective in adherence and motility, significantly reduced IL-8 promoter activity compared with the wild-type strain. We further demonstrate maximal involvement of extracellular signal-regulated kinase 1 ⁄ 2 ⁄ mitogen-activated protein kinase pathways to regulate IL-8 gene transcription. This study will help to design agents which could reduce the V. cholerae-induced inflammatory response and in the generation of safe vaccines