Poster Presentation BACPATH 2019

Flagellin from uropathogenic E. coli induces IL-10 during acute urinary tract infection (#221)

Dhruba Acharya 1 , Matthew J Sullivan 1 , Benjamin L Duell 1 , Lahiru Katupitiya 1 , Dean Gosling 1 , Michelle N Chamoun 1 , Asha Kakkanat 2 , Debasish Chattopadhyay 3 , Michael Crowley 4 , David K Crossman 4 , Mark A Schembri 2 , Glen C Ulett 1 3
  1. School of Medical Science and Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
  2. School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Queensland, Australia
  3. School of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama, USA
  4. Heflin Center for Genomic Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA

Innate immunity to urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) engages interleukin-10 (IL-10) early to regulate inflammation and promote the control of bladder infection. The mechanism of engagement of innate immunity by UPEC that leads to elicitation of IL-10 in the bladder is unknown. Here, we identify the major UPEC flagella filament, FliC as a key bacterial component sensed by the bladder innate immune system and responsible for the induction of IL-10 synthesis. IL-10 responses of human bladder epithelial cell-monocyte co-cultures as well as mouse bladder were shown to be triggered by flagella of three major UPEC representative strains CFT073, UTI89 and EC958. FliC purified to homogeneity induced IL-10 and other functionally related cytokines, including IL-6 but not IL-12. Characterization of the genome-wide innate immunological context of FliC-induced IL-10 in the bladder using RNA-sequencing identified a 1400-gene network of transcriptional and antibacterial defences induced by FliC. Of the FliC-responsive bladder transcriptome, the changes in expression of il10 and 808 additional genes were dependent on Toll-like receptor 5 (TLR5), according to comparative analysis of TLR5-deficient mice. Exploration of the potential of FliC and its associated innate immune signature in bladder to protect against UTI revealed significant benefit for the control of infection in mice that received FliC prophylactically or therapeutically after transurethral UPEC infection. We conclude that detection of FliC through TLR5 triggers rapid IL-10 synthesis in the bladder, and FliC represents a potential immune modulator for the treatment or prevention of UTI.