MP23-03 IL-6/STAT3 SIGNALING IS A HOST DETERMINANT OF UPEC VIRULENCE VIA ALTERED BACTERIAL INVASION AND INTRACELLULAR BACTERIAL COMMUNITY FORMATION

Abstract

You have accessJournal of UrologyInfections/Inflammation/Cystic Disease of the Genitourinary Tract: Kidney & Bladder II1 Apr 2018MP23-03 IL-6/STAT3 SIGNALING IS A HOST DETERMINANT OF UPEC VIRULENCE VIA ALTERED BACTERIAL INVASION AND INTRACELLULAR BACTERIAL COMMUNITY FORMATION Christina Ching, Sudipti Gupta, and Brian Becknell Christina ChingChristina Ching More articles by this author , Sudipti GuptaSudipti Gupta More articles by this author , and Brian BecknellBrian Becknell More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.735AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Our understanding of bacterial virulence in urinary tract infection (UTI) is primarily limited to identification of bacteria-specific determinants. Host mediators are less well known. IL-6 is a cytokine that is induced during UTI and results in subsequent Stat3 phosphorylation, but without readily apparent functional significance. We sought to evaluate the impact of IL-6/Stat3 signaling on host susceptibility to UTI via urothelial bacterial invasion and intracellular bacterial community formation. METHODS We performed in vivo and in vitro studies in order to evaluate the impact of IL-6 and Stat3 in bacterial invasion. We infected 6 week old female wild type (WT) C57BL/6J, IL-6 knock out (KO), or tamoxifen-inducible Stat3 conditional KO mice transurethrally with UPEC. We evaluated bladder and urine bacterial burden at varying time points of sacrifice by serial plating of tissue homogenates on LB agar and IBC formation via beta-galactosidase staining. We similarly evaluated the impact of recombinant IL-6 rescue in IL-6 KO mice on IBC formation and antimicrobial formation. We evaluated the impact of recombinant IL-6 incubation and Stat3 inhibition on intracellular bacterial invasion with gentamicin protection assay in serum starved 5637 urothelial cells. Results were evaluated by Mann-Whitney U test with p <0.05 being significant. RESULTS We observed an early transient (6 hours post inoculation - hpi) increase in bladder bacterial burden in our IL-6 KO mice compared to the WT controls, with a subsequent and persistent increase in urine bacterial burden starting at 24 hpi. This matched an initial significant difference in bladder IBC number in the IL-6 KO vs. WT that resolved by 24 hpi and was confirmed in our Stat3 CKO mice. Recombinant intravesical IL-6 rescued this phenotype in the IL-6 KO mouse and also significantly increased antimicrobial peptide expression. Similarly, we found that there was a significant decrease in bacterial invasion in vitro when 5637 cells were preincubated with IL-6. Stat3 inhibition resulted in a reversal of this phenotype with an increase in bacterial invasion on par with if not above unstimulated cells. CONCLUSIONS IL-6 plays an important role in host susceptibility to UTI as a mediator of bacterial invasion and IBC formation, potentially via antimicrobial peptide formation. Given IBC formation represents a significant bottleneck in UPEC survival during cystitis, these findings could suggest a role of IL-6 in UTI persistence and chronicity. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e282 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Christina Ching More articles by this author Sudipti Gupta More articles by this author Brian Becknell More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...