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HIF1A regulates xenophagic degradation of adherent and invasive Escherichia coli (AIEC).

ABSTRACT: The hypoxia inducible transcription factor HIF1 activates autophagy, a general catabolic pathway involved in the maintenance of cellular homeostasis. Dysfunction in both autophagy and HIF1 has been implicated in an increasing number of human diseases, including inflammatory bowel disease (IBD), such as Crohn disease (CD). Adherent invasive E. coli (AIEC) colonize ileal mucosa of CD patients and strongly promote gastrointestinal inflammatory disorders by activation of HIF-dependent responses. Here, we aim to characterize the contribution of HIF1 in xenophagy, a specialized form of autophagy involved in the degradation of intracellular bacteria. Our results showed that endogenous HIF1A knockdown increased AIEC survival in intestinal epithelial cells. We demonstrate that the increase in survival rate correlates with a dramatic impairment of the autophagic flux at the autolysosomal maturation step. Furthermore, we show that AIEC remained within single-membrane LC3-II-positive vesicles and that they were unable to induce the phosphorylation of ULK1. These results suggested that, in the absence of HIF1A, AIEC were found within LC3-associated phagosomes. Using blocking antibodies against TLR5 and CEACAM6, the 2 well-known AIEC-bound receptors, we showed that downstream receptor signaling was necessary to mediate ULK1 phosphorylation. Finally, we provide evidence that HIF1 mediates CEACAM6 expression and that CEACAM6 is necessary to recruit ULK1 in a bacteria-containing signaling hub. Collectively, these results identify a new function for HIF1 in AIEC-dedicated xenophagy, and suggest that coactivation of autophagy and HIF1A expression may be a potential new therapy to resolve AIEC infection in CD patients.

SUBMITTER: Mimouna S

PROVIDER: S-EPMC4502747 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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HIF1A regulates xenophagic degradation of adherent and invasive Escherichia coli (AIEC).

Mimouna Sanda S Bazin Marie M Mograbi Baharia B Darfeuille-Michaud Arlette A Brest Patrick P Hofman Paul P Vouret-Craviari Valérie V

Autophagy 20140101 12

The hypoxia inducible transcription factor HIF1 activates autophagy, a general catabolic pathway involved in the maintenance of cellular homeostasis. Dysfunction in both autophagy and HIF1 has been implicated in an increasing number of human diseases, including inflammatory bowel disease (IBD), such as Crohn disease (CD). Adherent invasive E. coli (AIEC) colonize ileal mucosa of CD patients and strongly promote gastrointestinal inflammatory disorders by activation of HIF-dependent responses. Her ...[more]

PMID: 25484075

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Project description:The adherent invasive Escherichia coli (AIEC) pathotype has been associated with the aetiology of Crohn's disease (CD). Scarce reports have shown the antimicrobial resistance (AMR) profiles of AIEC. Despite antibiotics not being recommended to treat CD, antimicrobial therapy could be useful in stratified patients, such as AIEC carriers. We examined the antimicrobial resistance profiles of AIEC strains to identify which therapies could be effective or confer a risk for such patients. Phenotypic resistance to 30 antimicrobials was tested according to CLSI standards. AIEC (n = 22) and non-pathogenic E. coli (non-AIEC) strains (n = 37) isolated from the gut mucosa of 31 CD patients and 18 controls were studied. De novo genome sequencing was carried out for 39 of the 59 strains, and AMR genes were searched using the DeepARG database in these genomes and 33 additional AIEC publicly available genomes. The strains isolated from CD and controls showed similar phenotypic AMR profiles. The genomic analysis did not reveal an increased prevalence of AMR genes. However, AIEC strains were more frequently resistant to ?-lactams than non-AIEC strains (11 AIEC (50%) and 5 non-AIEC (22%) strains were resistant to at least one ?-lactam; p < 0.042). Two AIEC strains were resistant to expanded-spectrum cephalosporins. One strain carried a plasmid-mediated AmpC ?-lactamase (CMY-69), and the other presented mutations in the promotor of the intrinsic chromosomal AmpC related to the hyperproduction of this enzyme. The rest of the strains were resistant to ?-lactams not including expanded-spectrum cephalosporins. The majority carried TEM-related ?-lactamases. Genomic analysis including external AIEC revealed that the gene sul1 encoding for sulphonamide resistance was more frequent in AIEC strains than non-AIEC strains (34.6% vs. 9.5%, p = 0.030). AMR in AIEC is a matter of concern regarding the putative implication of the pathotype in CD. The high proportion of AIEC resistant to ?-lactams warrants caution about the risk there may be in the use of these antimicrobials in AIEC-colonized CD patients.

Project description:BackgroundThe predominance of specific bacteria such as adherent-invasive Escherichia coli (AIEC) within the Crohn's disease (CD) intestine remains poorly understood with little evidence uncovered to support a selective pressure underlying their presence. Intestinal ethanolamine is however readily accessible during periods of intestinal inflammation, and enables pathogens to outcompete the host microbiota under such circumstances.MethodsQuantitative RT-PCR (qRT-PCR) to determine expression of genes central to ethanolamine metabolism; transmission electron microscopy to detect presence of bacterial microcompartments (MCPs); in vitro infections of both murine and human macrophage cell lines examining intracellular replication of the AIEC-type strain LF82 and clinical E. coli isolates in the presence of ethanolamine; determination of E. coli ethanolamine utilization (eut) operon transcription in faecal samples from healthy patients, patients with active CD and the same patients in remission following treatment.ResultsGrowth on the intestinal short chain fatty acid propionic acid (PA) stimulates significantly increased transcription of the eut operon (fold change relative to glucose: >16.9; p-value <.01). Additionally ethanolamine was accessible to intra-macrophage AIEC and stimulated significant increases in growth intracellularly when it was added extracellularly at concentrations comparable to those in the human intestine. Finally, qRT-PCR indicated that expression of the E. coli eut operon was increased in children with active CD compared to healthy controls (fold change increase: >4.72; P < .02). After clinical remission post-exclusive enteral nutrition treatment, the same CD patients exhibited significantly reduced eut expression (Pre vs Post fold change decrease: >15.64; P < .01).InterpretationOur data indicates a role for ethanolamine metabolism in selecting for AIEC that are consistently overrepresented in the CD intestine. The increased E. coli metabolism of ethanolamine seen in the intestine during active CD, and its decrease during remission, indicates ethanolamine use may be a key factor in shaping the intestinal microbiome in CD patients, particularly during times of inflammation. FUND: This work was funded by Biotechnology and Biological Sciences Research Council (BBSRC) grants BB/K008005/1 & BB/P003281/1 to DMW; by a Tenovus Scotland grant to MJO; by Glasgow Children's Hospital Charity, Nestle Health Sciences, Engineering and Physical Sciences Research Council (EPSRC) and Catherine McEwan Foundation grants awarded to KG; and by a Natural Environment Research Council (NERC) fellowship (NE/L011956/1) to UZI. The IBD team at the Royal Hospital for Children, Glasgow are supported by the Catherine McEwan Foundation and Yorkhill IBD fund. RKR and RH are supported by NHS Research Scotland Senior fellowship awards.

Dataset Information

HIF1A regulates xenophagic degradation of adherent and invasive Escherichia coli (AIEC).

Publications

HIF1A regulates xenophagic degradation of adherent and invasive Escherichia coli (AIEC).

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