Identification of the ovine mannose receptor and its possible role in Visna/Maedi virus infection

This study aims to characterize the mannose receptor (MR) gene in sheep and its role in ovine visna/maedi virus (VMV) infection. The deduced amino acid sequence of ovine MR was compatible with a transmembrane protein having a cysteine-rich ricin-type amino-terminal region, a fibronectin type II repeat, eight tandem C-type lectin carbohydrate-recognition domains (CRD), a transmembrane region, and a cytoplasmic carboxy-terminal tail. The ovine and bovine MR sequences were closer to each other compared to human or swine MR. Concanavalin A (ConA) inhibited VMV productive infection, which was restored by mannan totally in ovine skin fibroblasts (OSF) and partially in blood monocyte-derived macrophages (BMDM), suggesting the involvement of mannosylated residues of the VMV ENV protein in the process. ConA impaired also syncytium formation in OSF transfected with an ENV-encoding pN3-plasmid. MR transcripts were found in two common SRLV targets, BMDM and synovial membrane (GSM) cells, but not in OSF. Viral infection of BMDM and especially GSM cells was inhibited by mannan, strongly suggesting that in these cells the MR is an important route of infection involving VMV Env mannosylated residues. Thus, at least three patterns of viral entry into SRLV-target cells can be proposed, involving mainly MR in GSM cells (target in SRLV-induced arthritis), MR in addition to an alternative route in BMDM (target in SRLV infections), and an alternative route excluding MR in OSF (target in cell culture). Different routes of SRLV infection may thus coexist related to the involvement of MR differential expression

Contribution of the alkylquinolone quorum sensing system to the interaction of Pseudomonas aeruginosa with bronchial epithelial cells.

Pseudomonas aeruginosa causes infections in patients with compromised epithelial 32 barrier function. Multiple virulence factors produced by P. aeruginosa are controlled 33 by quorum sensing (QS) via 2-alkyl-4(1H)-quinolone (AQ) signal molecules. Here we 34 investigated the impact of AQs on P. aeruginosa PAO1 infection of differentiated 35 human bronchial epithelial cells (HBECs). The pqsA-E operon is responsible for the 36 biosynthesis of AQs including the 2-alkyl-3-hydroxy-4-quinolones, 4-hydroxy-2-37 alkylquinolines and 4-hydroxy-2-alkylquinoline N-oxides as exemplified by PQS, 38 HHQ and HQNO, respectively. PQS and HHQ both act as QS signal molecules while 39 HQNO is a cytochrome inhibitor. PqsE contributes both to AQ biosynthesis and 40 promotes virulence in a PQS-independent manner. Our results show that PQS, HHQ 41 and HQNO were produced during PAO1 infection of HBECs, but no differences in 42 growth or cytotoxicity were apparent when PAO1 and an AQ-negative ΔpqsA mutant 43 were compared. Both strains promoted synthesis of inflammatory cytokines TNF-α, 44 interleukin (IL)-6 and IL-17C by HBECs and provision of exogenous PQS negatively 45 impacted on this response without affecting bacterial growth. Expression of pqsE and 46 the PQS-independent PqsE-regulated genes mexG and lecA was detected during HBEC 47 infection. Levels were reduced in the ΔpqsA mutant, i.e. in the absence of PQS, and 48 increased by exogenous PQS. These results support an AQ-independent role for PqsE 49 during initial infection of HBEC by P. aeruginosa and for PQS as an enhancer of PqsE 50 and PqsE-controlled virulence determinants and as an immunomodulato

TLR4, but Neither Dectin-1 nor Dectin-2, Participates in the Mollusk Hemocyanin-Induced Proinflammatory Effects in Antigen-Presenting Cells From Mammals

Funding This study was supported by CONICYT-CHILE FONDECYT Regular Grant 1151337 to MB. FONDAP 15130011 to SL. CONICYT-CHILE National Ph.D. Fellowships were awarded to JJ (CONICYT-PCHA/Doctorado Nacional/2013-21130683) and to JO-Q (CONICYT-PFCHA/Doctorado Nacional/2017-21171588). FS holds a postdoctoral fellowship from the National Commission for Scientific and Technological Research (CONICYT), Chile. Funding was provided by the Wellcome Trust (102705, 097377), the MRC Centre for Medical Mycology and the University of Aberdeen (MR/N006364/1) to GB. Acknowledgments We thank Dr. María Rosa Bono, Dr. Sergio Vargas, and Dr. Juan Carlos Aguillón from Universidad de Chile and Dr. Mónica Imarai from Universidad de Santiago, Chile for helpful comments.Peer reviewedPublisher PD

Granulocyte-macrophage colony stimulatory factor enhances the pro-inflammatory response of interferon-γ-treated macrophages to pseudomonas aeruginosa infection

Pseudomonas aeruginosa is an opportunistic pathogen that can cause severe infections at compromised epithelial surfaces, such those found in burns, wounds, and in lungs damaged by mechanical ventilation or recurrent infections, particularly in cystic fibrosis (CF) patients. CF patients have been proposed to have a Th2 and Th17-biased immune response suggesting that the lack of Th1 and/or over exuberant Th17 responses could contribute to the establishment of chronic P. aeruginosa infection and deterioration of lung function. Accordingly, we have observed that interferon (IFN)-γ production by peripheral blood mononuclear cells from CF patients positively correlated with lung function, particularly in patients chronically infected with P. aeruginosa. In contrast, IL-17A levels tended to correlate negatively with lung function with this trend becoming significant in patients chronically infected with P. aeruginosa. These results are in agreement with IFN-γ and IL-17A playing protective and detrimental roles, respectively, in CF. In order to explore the protective effect of IFN-γ in CF, the effect of IFN-γ alone or in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), on the ability of human macrophages to control P. aeruginosa growth, resist the cytotoxicity induced by this bacterium or promote inflammation was investigated. Treatment of macrophages with IFN-γ, in the presence and absence of GM-CSF, failed to alter bacterial growth or macrophage survival upon P. aeruginosa infection, but changed the inflammatory potential of macrophages. IFN-γ caused up-regulation of monocyte chemoattractant protein-1 (MCP-1) and TNF-α and down-regulation of IL-10 expression by infected macrophages. GM-CSF in combination with IFN-γ promoted IL-6 production and further reduction of IL-10 synthesis. Comparison of TNF-α vs. IL-10 and IL-6 vs. IL-10 ratios revealed the following hierarchy in regard to the pro-inflammatory potential of human macrophages infected with P. aeruginosa: untreated < treated with GM-CSF < treated with IFN-γ < treated with GM-CSF and IFN-γ

Caracterización de una proteína estructural del virus de la peste porcina africana

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 16-nov-199

IFN-γ and IL-17A differentially influence the response of human macrophages and neutrophils to Pseudomonas aeruginosa infection

Macrophages are important orchestrators of inflammation during bacterial infection acting both as effector cells and as regulators of neutrophil recruitment and life span. Differently activated macrophage populations with distinct inflammatory and microbicidal potential have been described. Our previous work unveiled a positive and a negative correlation between levels of IFN-γ and IL-17A, respectively, and lung function in cystic fibrosis, particularly in patients chronically infected with P. aeruginosa. This study sought to define key parameters in human anti-bacterial immunity under Th1- and Th17-dominated inflammatory conditions; the final aim was to identify unique characteristics that could be fine-tuned therapeutically to minimise tissue damage while maximising bacterial clearance. Towards this aim neutrophils were incorporated into cultures of macrophages treated with IFN-γ or IL-17A and infected with P. aeruginosa. The intent of this design was to model (i) initiation of inflammation by infected macrophages and (ii) delayed arrival of neutrophils and their exposure to macrophage-derived cytokines. Under these conditions IFN-γ decreased bacterial killing and promoted production of the monocyte chemoattractant MCP-1. In contrast, IL-17A promoted bacterial killing but did not affect MCP-1 production. Secretion of the pyrogen IL-1β was significantly lower in the presence of IFN-γ compared to IL-17A and correlated with levels of IL1B transcript in infected macrophages. These findings support the validity of this model to investigate human anti-bacterial immunity. Based on these observations, the protective and damaging roles of IFN-γ and IL-17A, respectively, during P. aeruginosa infection could be caused by their contrasting effects on IL-1β and MCP-1 production

Structural model for the mannose receptor family uncovered by electron microscopy of Endo180 and the mannose receptor

9 p.-6 fig.The mannose receptor family comprises four members in mammals, Endo180 (CD280), DEC-205 (CD205), phospholipase A(2) receptor (PLA(2)R) and the mannose receptor (MR, CD206), whose extracellular portion contains a similar domain arrangement: an N-terminal cysteine-rich domain (CysR) followed by a single fibronectin type II domain (FNII) and 8-10 C-type lectin-like domains (CTLDs). These proteins mediate diverse functions ranging from extracellular matrix turnover through collagen uptake to homeostasis and immunity based on sugar recognition. Endo180 and the MR are multivalent transmembrane receptors capable of interacting with multiple ligands; in both receptors FNII recognizes collagens, and a single CTLD retains lectin activity (CTLD2 in Endo180 and CTLD4 in MR). It is expected that the overall conformation of these multivalent molecules would deeply influence their function as the availability of their binding sites could be altered under different conditions. However, conflicting reports have been published on the three-dimensional arrangement of these receptors. Here, we have used single particle electron microscopy to elucidate the three-dimensional organization of the MR and Endo180. Strikingly, we have found that both receptors display distinct three-dimensional structures, which are, however, conceptually very similar: a bent and compact conformation built upon interactions of the CysR domain and the lone functional CTLD. Biochemical and electron microscopy experiments indicate that, under a low pH mimicking the endosomal environment, both MR and Endo180 experience large conformational changes. We propose a structural model for the mannose receptor family where at least two conformations exist that may serve to regulate differences in ligand selectivity.This work was supported by Projects SAF2002-01715 and GEN2003-20239-C06-06 from the Spanish Ministry of Education (to J. B., A. R.-C., and O. L.), Breakthrough Breast Cancer Research, The Wellcome Trust (to C. M. I.), the E. P. Abraham Trust Research Fund, and the Edward Jenner Institute for Vaccine Research and the Medical Research Council, United Kingdom (to L. M.-P.).Peer reviewe