Toggle Main Menu Toggle Search

Open Access padlockePrints

Evasion of toll-like receptor recognition by Escherichia coli is mediated via population level regulation of flagellin production

Lookup NU author(s): Aaron Tan, Qusai Alsenani, Marcelo Lanz, Christopher Birchall, Lauren Drage, David Picton, Dr Catherine Mowbray, Ased Ali, Professor Christopher HardingORCiD, Rob Pickard, Dr Judith HallORCiD, Dr Phillip AldridgeORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Copyright © 2023 Tan, Alsenani, Lanz, Birchall, Drage, Picton, Mowbray, Ali, Harding, Pickard, Hall and Aldridge.Uropathogenic Escherichia coli is a major cause of urinary tract infections. Analysis of the innate immune response in immortalized urothelial cells suggests that the bacterial flagellar subunit, flagellin, is key in inducing host defenses. A panel of 48 clinical uro-associated E. coli isolates recovered from either cystitis, pyelonephritis asymptomatic bacteriuria (ABU) or UTI-associated bacteraemia infections were characterized for motility and their ability to induce an innate response in urothelial cells stably transfected with a NF-κB luciferase reporter. Thirty-two isolates (67%) were identified as motile with strains recovered from cystitis patients exhibiting an uneven motility distribution pattern; seven of the cystitis isolates were associated with a > 5-fold increase in NF-κB signaling. To explore whether the NF-κB signaling response reflected antigenic variation, flagellin was purified from 14 different isolates. Purified flagellin filaments generated comparable NF-κB signaling responses, irrespective of either the source of the isolate or H-serotype. These data argued against any variability between isolates being related to flagellin itself. Investigations also argued that neither TLR4 dependent recognition of bacterial lipopolysaccharide nor growth fitness of the isolates played key roles in leading to the variable host response. To determine the roles, if any, of flagellar abundance in inducing these variable responses, flagellar hook numbers of a range of cystitis and ABU isolates were quantified. Images suggested that up to 60% of the isolate population exhibited flagella with the numbers averaging between 1 and 2 flagella per bacterial cell. These data suggest that selective pressures exist in the urinary tract that allow uro-associated E. coli strains to maintain motility, but exploit population heterogeneity, which together function to prevent host TLR5 recognition and bacterial killing.

Publication metadata

Author(s): Tan A, Alsenani Q, Lanz M, Birchall C, Drage LKL, Picton D, Mowbray C, Ali A, Harding C, Pickard RS, Hall J, Aldridge PD

Publication type: Article

Publication status: Published

Journal: Frontiers in Microbiology

Year: 2023

Volume: 14

Online publication date: 23/03/2023

Acceptance date: 03/03/2023

Date deposited: 04/05/2023

ISSN (electronic): 1664-302X

Publisher: Frontiers Media S.A.


DOI: 10.3389/fmicb.2023.1093922


Altmetrics provided by Altmetric