mcr-1 Gene Expression Modulates the Inflammatory Response of Human Macrophages to Escherichia coli (original) (raw)
Related papers
Inflammation Research, 2006
Objective and Background: Macrophages are known to be one of the initial responders to bacterial infection. While infection of macrophages with bacteria induces apoptosis, a pro-inflammatory response is also elicited. Thus, the aim of this study is to further elucidate the differential effect of infections with bacteria on the survival and function of macrophages. Methods and results: THP-1 monocytic cells induced to differentiate into macrophages were infected with non-pathogenic Escherichia coli (E. coli) and analyzed for apoptosis and inflammatory response over time. Following infection with E. coli macrophages underwent apoptosis which was reduced by the general caspase inhibitor, zVAD.fmk. Inhibition of caspase activity resulted in increased DNA binding activity of NF-κB and enhanced production of NF-κB-dependent reporter gene expression following infection. Increased activity of NF-κB was independent of IκBα since IκBα degradation was unaffected by zVAD.fmk. Further, suppression of caspase activity reduced the proteolytic cleavage of NF-κB. The increased activity of NF-κB in the zVAD.fmk-treated macrophages was associated with a markedly enhanced production of pro-inflammatory cytokines and elimination of E. coli. Conclusion: These data indicate that infection of macrophages with E. coli induces a caspase-dependent inhibition of NF-κB that results in a reduced production of pro-inflammatory cytokines and impaired clearance of bacteria.
Nature communications, 2017
MCR-1 is a lipid A modifying enzyme that confers resistance to the antibiotic colistin. Here, we analyse the impact of MCR-1 expression on E. coli morphology, fitness, competitiveness, immune stimulation and virulence. Increased expression of mcr-1 results in decreased growth rate, cell viability, competitive ability and significant degradation in cell membrane and cytoplasmic structures, compared to expression of catalytically inactive MCR-1 (E246A) or MCR-1 soluble component. Lipopolysaccharide (LPS) extracted from mcr-1 strains induces lower production of IL-6 and TNF, when compared to control LPS. Compared to their parent strains, high-level colistin resistance mutants (HLCRMs) show reduced fitness (relative fitness is 0.41-0.78) and highly attenuated virulence in a Galleria mellonella infection model. Furthermore, HLCRMs are more susceptible to most antibiotics than their respective parent strains. Our results show that the bacterium is challenged to find a delicate equilibrium...
Journal of Leukocyte Biology, 2005
Phagocytes are well-known effectors of the innate immune system to produce proinflammatory cytokines and chemokines such as tumor necrosis factor ␣ (TNF-␣), interleukin (IL)-1, and IL-8 during infections. Here, we show that infection of monocytes with wild-type Escherichia coli K1, which causes meningitis in neonates, suppresses the production of cytokines and chemokines (TNF-␣, regulated on activation, normal T expressed and secreted, macrophage-inflammatory protein-1, IL-1, and
BMC medical …, 2005
The use of live microorganisms to influence positively the course of intestinal disorders such as infectious diarrhea or chronic inflammatory conditions has recently gained increasing interest as a therapeutic alternative. In vitro and in vivo investigations have demonstrated that probiotic-host eukaryotic cell interactions evoke a large number of responses potentially responsible for the effects of probiotics. The aim of this study was to improve our understanding of the E. coli Nissle 1917-host interaction by analyzing the gene expression pattern initiated by this probiotic in human intestinal epithelial cells.
Infection and Immunity, 2006
Toll-like receptors (TLRs) are key components of the innate immune system that trigger antimicrobial host defense responses. The aim of the present study was to analyze the effects of probiotic Escherichia coli Nissle strain 1917 in experimental colitis induced in TLR-2 and TLR-4 knockout mice. Colitis was induced in wild-type (wt), TLR-2 knockout, and TLR-4 knockout mice via administration of 5% dextran sodium sulfate (DSS). Mice were treated with either 0.9% NaCl or 10 7 E. coli Nissle 1917 twice daily, followed by the determination of disease activity, mucosal damage, and cytokine secretion. wt and TLR-2 knockout mice exposed to DSS developed acute colitis, whereas TLR-4 knockout mice developed significantly less inflammation.
Cytokine, 2011
Introduction: We investigated the role of PI3-K, MAP kinases, and heterotrimeric G proteins in inducing cytokines production in human whole blood cultures stimulated by viable Escherichia coli (E. coli) clinical strains. Materials and methods: We used eight E. coli strains that belong to different phylogenetic groups and presented by different antibiotic resistance patterns. Whole blood from healthy volunteers was incubated at 37°C for 150 min, with lipopolysaccharide (LPS) from E. coli O111:B4 or selected viable E. coli clinical strains, with or without SB202190 (p38 inhibitor), PD98059 (ERK inhibitor), PTX (pertussis toxin; heterotrimeric G proteins inhibitor), wortmaninn (PI3-K inhibitor). The TNF-a, IL-1b, IL-10 and IFN-c concentrations were measured in culture supernatants (ELISA). Results: IL-10 and IFN-c were not detectable. Susceptible strains induced higher TNF-a and IL-1b productions than b-lactam resistant strains (p < 0.05), with no difference between phylogenetic groups. A transformed strain carrying a plasmid-mediated AmpC-b-lactamase gene (CMY-2) induced lower TNF-a and IL-1b production than the parent wild type strain (p < 0.05). SB202190 (p38 inhibitor) and PD98059 (ERK inhibitor) reduced TNF-a concentrations by, respectively, 80% (p < 0.05) and 50% (p < 0.05). Wortmaninn (PI3-K inhibitor) had no significant effect. PTX (heterotrimeric G proteins inhibitor) altered TNF-a production after viable bacteria stimulation (1.7-fold increase; p < 0.05) but not after LPS (TLR-4) stimulation. Regarding IL-1b, wortmaninn, SB202190 and PTX had no significant effect whereas PD98059 significantly decreased production in whole cell cultures (p < 0.05). Conclusion: Susceptible strains induce greater TNF-a and IL-1b productions than resistant strains. ERK kinase plays a major role in viable E. coli strains inducing TNF-a and IL-1b production. E. coli exerts an effect on the pertussis toxin-sensitive G-protein through a TLR-4-independent mechanism.
Journal of Leukocyte Biology, 2003
Macrophages have a central role in innate-immune responses to bacteria. In the present work, we show that infection of human macrophages with Gram-positive pathogenic Streptococcus pyogenes or nonpathogenic Lactobacillus rhamnosus GG enhances mRNA expression of inflammatory chemokine ligands CCL2/monocyte chemoattractant protein-1 (MCP-1), CCL3/macrophage-inflammatory protein-1␣ (MIP-1␣), CCL5/ regulated on activation, normal T expressed and secreted, CCL7/MCP-3, CCL19/MIP-3, and CCL20/MIP-3␣ and CXC chemokine ligands CXCL8/interleukin (IL)-8, CXCL9/monokine induced by interferon-␥ (IFN-␥), and CXCL10/IFNinducible protein 10. Bacteria-induced CCL2, CCL7, CXCL9, and CXCL10 mRNA expression was partially dependent on ongoing protein synthesis. The expression of these chemokines and of CCL19 was dependent on bacteria-induced IFN-␣/ production. CCL19 and CCL20 mRNA expression was up-regulated by IL-1 or tumor necrosis factor ␣ (TNF-␣), and in addition, IFN-␣ together with TNF-␣ further enhanced CCL19 gene expression. Synergy between IFN-␣ and TNF-␣ was also seen for CXCL9 and CXCL10 mRNA expression. Bacteria-stimulated macrophage supernatants induced the migration of T helper cell type 1 (Th1) cells, suggesting that in human macrophages, these bacteria can stimulate efficient inflammatory chemokine gene expression including those that recruit Th1 cells to the site of inflammation. Furthermore, L. rhamnosus-induced Th1 chemokine production could in part explain the proposed antiallergenic properties of this bacterium. J. Leukoc. Biol. 74: 000 -000; 2003.
Journal of Leukocyte Biology, 2008
Macrophages are phagocytes that recognize bacteria and subsequently activate appropriate innate and adaptive immune responses. TLRs are essential in identifying conserved bacterial structures and in initiating and mediating innate immune responses. In this work, we have characterized TLR gene expression in human monocyte-derived macrophages in response to stimulation with two live Gram-positive bacteria, a human commensal and probiotic Lactobacillus rhamnosus GG (LGG), and an important human pathogen Streptococcus pyogenes. LGG and S. pyogenes enhanced TLR2 expression in macrophages. LGG and S. pyogenes also required TLR2 for NF-B activation. Only pathogenic S. pyogenes was able to up-regulate TLR3 and TLR7 gene expression. This up-regulation was dependent on IFN-␣/, as neutralizing anti-IFN-␣/ antibodies reduced S. pyogenes-induced TLR3 and TLR7 mRNA expression. Our results show that despite similarities, TLR responses of macrophages differ for a Gram-positive probiotic and a pathogen. Our data suggest that macrophages can discriminate between probiotic and pathogenic bacteria by IFNmediated TLR gene regulation. J. Leukoc. Biol. 84: 000 -000; 2008.
PLOS ONE, 2019
Macrophages (Mϕs) play a central role in mucosal immunity by pathogen sensing and instruction of adaptive immune responses. Prior challenge to endotoxin can render Mφs refractory to secondary exposure, suppressing the inflammatory response. Previous studies demonstrated a differential subset-specific sensitivity to endotoxin tolerance (ET), mediated by LPS from the oral pathogen, Porphyromonas gingivalis (PG). The aim of this study was to investigate ET mechanisms associated with Mφ subsets responding to entropathogenic E. coli K12-LPS. M1-and M2-like Mφs were generated in vitro from the THP-1 cell line by differentiation with PMA and Vitamin D 3 , respectively. This study investigated ET mechanisms induced in M1 and M2 Mφ subsets, by measuring modulation of expression by RT-PCR, secretion of cytokines by sandwich ELISA, LPS receptor, TLR4, as well as endogenous TLR inhibitors, IRAK-M and Tollip by Western blotting. In contrast to PG-LPS tolerisation, E. coli K12-LPS induced ET failed to exhibit a subset-specific response with respect to the pro-inflammatory cytokine, TNFα, whereas exhibited a differential response for IL-10 and IL-6. TNFα expression and secretion was significantly suppressed in both M1-and M2like Mφs. IL-10 and IL-6, on the other hand, were suppressed in M1s and refractory to suppression in M2s. ET suppressed TLR4 mRNA, but not TLR4 protein, yet induced differential augmentation of the negative regulatory molecules, Tollip in M1 and IRAK-M in M2 Mφs. In conclusion, E. coli K12-LPS differentially tolerises Mφ subsets at the level of anti-inflammatory cytokines, associated with a subset-specific divergence in negative regulators and independent of TLR4 down-regulation.