Background & Aims
Adherent-invasive E. coli (AIEC) are implicated in inflammatory bowel disease (IBD), and mitochondrial dysfunction has been observed in IBD-patient biopsies. As a novel aspect of AIEC-epithelial interaction we hypothesized that E. coli (strain LF82) would elicit substantial disruption of epithelial mitochondrial form and function.
Monolayers of human colon-derived epithelial cell lines were exposed to E. coli-LF82 or commensal E. coli and RNA-sequence analysis, mitochondrial function (ATP synthesis) and dynamics (mitochondrial network imaging, immunoblotting for fission and fusion proteins), and epithelial permeability (transepithelial resistance, flux of FITC-dextran and bacteria) were assessed.
E. coli-LF82 significantly affected epithelial expression of ∼8600 genes, many relating to mitochondrial function. E. coli-LF82-infected epithelia displayed swollen mitochondria, reduced mitochondrial membrane potential and ATP, and fragmentation of the mitochondrial network: events not observed with dead E. coli-LF82, medium from bacterial cultures, or control E. coli. Treatment with Mdivi1 (inhibits dynamin-related peptide 1 (Drp1), GTPase principally responsible for mitochondrial fission) or P110 (prevents Drp1 binding to mitochondrial fission 1 protein) partially reduced E. coli-LF82-induced mitochondrial fragmentation in the short-term. E. coli-LF82-infected epithelia showed loss of the long isoform of optic atrophy factor 1 (OPA1-L), which mediates mitochondrial fusion. Mdivi1 reduced the magnitude of E. coli-LF82 induced increased transepithelial flux of FITC-dextran. By 8h post-infection, increased cytosolic cytochrome C and DNA fragmentation were apparent without evidence of caspase-3 or apoptosis inducing factor (AIF) activation.
Epithelial mitochondrial fragmentation caused by E. coli-LF82 could be targeted to maintain cellular homeostasis and mitigate infection-induced loss of epithelial barrier function.
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Disruption of the mitochondrial network is uncovered as a novel aspect of attaching-invasive E. coli (strain LF82: implicated in IBD) interaction with epithelial cells; the inhibition of which reduced the magnitude of the bacteria-evoked increases in epithelial permeability.
NL Mancini: study concept and design; acquisition of data; analysis and interpretation of data; drafting of the manuscript; statistical analysis
S Rajeev: acquisition of data; analysis and interpretation of data
TS Jayme: acquisition of data; analysis and interpretation of data
A Wang: acquisition of data; analysis and interpretation of data
ÅV Keita: acquisition of data; analysis and interpretation of data
M Workentine: analysis and interpretation of data
S Hamed: acquisition of data; analysis and interpretation of data
JD Soderhölm: interpretation of data; critical revision of the manuscript for important intellectual content
F Lopes: acquisition of data
TE Shutt: interpretation of data; critical revision of the manuscript for important intellectual content
J Shearer: interpretation of data; critical revision of the manuscript for important intellectual content
DM McKay: study concept and design; interpretation of data; drafting of the manuscript; critical revision of the manuscript for important intellectual content; obtained funding; study supervision
Disclosures: The authors declare no conflict of interest.
Funding: Funding for this study was provided by a grant from the Canadian Institutes of Health Research to D.M. McKay (PJT-153074).
Acknowledgements: We thank Dr. Hena R. Ramay affiliated with the bioinformatics platform of the International Microbiome Centre at University of Calgary.
Data deposited in NCBI’s Gene Expression Omnibus and are accessible through GEO Series accession numbers GSE154121 and GSE154122 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE154121).
© 2020 The Authors. Published by Elsevier Inc. on behalf of the AGA Institute.
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