title: Inhibition of TIR domain signaling by TcpC: MyD88-dependent and independent effects on Escherichia coli virulence.
abstract: Toll-like receptor signaling requires functional Toll/interleukin-1 (IL-1) receptor (TIR) domains to activate innate immunity. By producing TIR homologous proteins, microbes inhibit host response induction and improve their own survival. The TIR homologous protein TcpC was recently identified as a virulence factor in uropathogenic Escherichia coli (E. coli), suppressing innate immunity by binding to MyD88. This study examined how the host MyD88 genotype modifies the in vivo effects of TcpC and whether additional, TIR-domain containing proteins might be targeted by TcpC. In wild type mice (wt), TcpC enhanced bacterial virulence, increased acute mortality, bacterial persistence and tissue damage after infection with E. coli CFT073 (TcpC+), compared to a ΔTcpC deletion mutant. These effects were attenuated in Myd88(-/-) and Tlr4(-/-) mice. Transcriptomic analysis confirmed that TcpC inhibits MYD88 dependent gene expression in CFT073 infected human uroepithelial cells but in addition the inhibitory effect included targets in the TRIF and IL-6/IL-1 signaling pathways, where MYD88 dependent and independent signaling may converge. The effects of TcpC on bacterial persistence were attenuated in Trif (-/-) or Il-1β (-/-) mice and innate immune responses to ΔTcpC were increased, confirming that Trif and Il-1β dependent targets might be involved in vivo, in addition to Myd88. Furthermore, soluble TcpC inhibited Myd88 and Trif dependent TLR signaling in murine macrophages. Our results suggest that TcpC may promote UTI-associated pathology broadly, through inhibition of TIR domain signaling and downstream pathways. Dysregulation of the host response by microbial TcpC thus appears to impair the protective effects of innate immunity, while promoting inflammation and tissue damage.
authors.affiliation: Department of Microbiology, Institute of Laboratory Medicine, Lund University, Sweden.
authors.forename: Manisha
authors.initials: M
authors.lastname: Yadav
authors.forename: Jingyao
authors.initials: J
authors.lastname: Zhang
authors.forename: Hans
authors.initials: H
authors.lastname: Fischer
authors.forename: Wen
authors.initials: W
authors.lastname: Huang
authors.forename: Nataliya
authors.initials: N
authors.lastname: Lutay
authors.forename: Christine
authors.initials: C
authors.lastname: Cirl
authors.forename: Josephine
authors.initials: J
authors.lastname: Lum
authors.forename: Thomas
authors.initials: T
authors.lastname: Miethke
authors.forename: Catharina
authors.initials: C
authors.lastname: Svanborg
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000502:physiology; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D004926:Escherichia coli / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000276:immunology / Q000378:metabolism / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007113:Immunity, Innate; D007124:Immunoenzyme Techniques; D053583:Interleukin-1beta / Q000502:physiology; D007680:Kidney Neoplasms / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000502:physiology; D051193:Toll-Like Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D015415:Biomarkers; D029968:Escherichia coli Proteins; D053583:Interleukin-1beta; D053594:Myeloid Differentiation Factor 88; D012333:RNA, Messenger; D017472:Receptors, Interleukin-1; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D037521:Virulence Factors; C507780:Myd88 protein, mouse; C476286:Ticam1 protein, mouse; C549538:TcpC protein, E coli; C493487:Tlr4 protein, mouse