CD14- and Toll-Like Receptor-Dependent Activation of Bladder Epithelial Cells by Lipopolysaccharide and Type 1 Piliated<i>Escherichia coli</i>

Schilling, Joel D.; Martin, Steven M.; Hunstad, David A.; Patel, Khushbu; Mulvey, Matthew; Justice, Sheryl S.; Lorenz, Robin G.; Hultgren, Scott J.

doi:10.1128/iai.71.3.1470-1480.2003

Cited by 136 publications

(150 citation statements)

References 51 publications

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“…During the first 24 h after a single transurethral inoculation of 1-2 ϫ 10 7 CFUs, UTI89 binds to and invades the bladder urothelium. This host-pathogen interaction activates several innate defenses (40)(41)(42). A fraction of the original inoculum is able to survive or subvert host defenses, invade superficial umbrella cells, escape into the cytoplasm, and rapidly replicate into IBCs.…”

Section: Results Fimh Gene Is Under Positive Selection In a Subset Ofmentioning

confidence: 99%

Positive selection identifies an in vivo role for FimH during urinary tract infection in addition to mannose binding

Chen

Hung

Pinkner

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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FimH, the type 1 pilus adhesin of uropathogenic Escherichia coli (UPEC), contains a receptor-binding domain with an acidic binding pocket specific for mannose. The fim operon, and thus type 1 pilus production, is under transcriptional control via phase variation of an invertible promoter element. FimH is critical during urinary tract infection for mediating colonization and invasion of the bladder epithelium and establishment of intracellular bacterial communities (IBCs). In silico analysis of FimH gene sequences from 279 E. coli strains identified specific amino acids evolving under positive selection outside of its mannose-binding pocket. Mutating two of these residues (A27V/V163A) had no effect on phase variation, pilus assembly, or mannose binding in vitro. However, compared to wild-type, this double mutant strain exhibited a 10,000-fold reduction in mouse bladder colonization 24 h after inoculation and was unable to form IBCs even though it bound normally to mannosylated receptors in the urothelium. In contrast, the single A62S mutation altered phase variation, reducing the proportion of piliated cells, reduced mannose binding 8-fold, and decreased bladder colonization 30-fold in vivo compared to wild-type. A phase-locked ON A62S mutant restored virulence to wild-type levels even though in vitro mannose binding remained impaired. Thus, positive selection analysis of FimH has separated mannose binding from in vivo fitness, suggesting that IBC formation is critical for successful infection of the mammalian bladder, providing support for more general use of in silico positive selection analysis to define the molecular underpinnings of bacterial pathogenesis.type 1 pili ͉ uropathogenic Escherichia coli

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Section: Results Fimh Gene Is Under Positive Selection In a Subset Ofmentioning

confidence: 99%

Positive selection identifies an in vivo role for FimH during urinary tract infection in addition to mannose binding

Chen

Hung

Pinkner

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

165

209

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“…Epithelial cells must be protected from constant TLR activation by commensals and their PAMP, in order for mucosal integrity to be maintained. The epithelial cells thus lack co-receptors like CD14 [6][7][8][9][10][11], and in addition, commensals have been suggested to actively suppress epithelia responses through NF-jB [12,13]. Yet, mucosal pathogens evoke rapid TLR4-dependent responses at mucosal sites, suggesting that alternative ligands and receptors might be involved in mucosal TLR activation.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of pathogen‐specific TLR4 activation in the mucosa: Fimbriae, recognition receptors and adaptor protein selection

et al. 2006

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The mucosal host defence discriminates pathogens from commensals, and prevents infection while allowing the normal flora to persist. Paradoxically, Toll-like receptors (TLR) control the mucosal defence against pathogens, even though the TLR recognise conserved molecules like LPS, which are shared between pathogens and commensals. This study proposes a mechanism of pathogen-specific mucosal TLR4 activation, involving adhesive ligands and their host cell receptors. TLR4 signalling was activated in CD14-negative, LPS-unresponsive epithelial cells by P fimbriated, uropathogenic Escherichia coli but not by a mutant lacking fimbriae. Epithelial TLR4 signalling in vivo involved the glycosphingolipid receptors for P fimbriae and the adaptor proteins Toll/IL-1R (TIR) domain-containing adaptor inducing IFN-b (TRIF)/TRIF-related adaptor molecule (TRAM), but myeloid differentiation protein 88 (MyD88)/TIR domain-containing adaptor protein were not required for the epithelial response. Substituting the P fimbriae with type 1 fimbriae changed TLR4 signalling from the TRIF to the MyD88 adaptor pathway. In addition, the adaptor proteins and the fimbrial type were found to influence bacterial clearance. Trif -/-and Tram -/-mice remained infected with P fimbriated E. coli but cleared thetype 1 fimbriated strain, while Myd88 -/-mice became carriers of both the P and the type 1 fimbriated bacteria. Thus, TLR4 may be engaged specifically by pathogens, when the proper cell surface receptors are engaged by virulence ligands. IntroductionToll-like receptors (TLR) control the innate host defence at mucosal surfaces and yet commensals do not induce an inflammatory response at those sites. The relative inertia to the commensals is paradoxical, as the TLR recognise conserved pathogen-associated molecular patterns (PAMP), which are present on both pathogenic and commensal bacteria. Lipolysaccharide (LPS), flagellin, peptidoglycan or DNA may bind directly to the TLR but in addition, co-receptors are needed to enhance the TLR response to these conserved ligands [1][2][3]. Myeloid cells use CD14 and MD-2 as co-receptors for LPS in TLR4 signalling, and minute amounts of LPS may elicit a strong systemic inflammatory response [4,5]. However, the TLR response to pathogen attack at mucosal surfaces is controlled by different interactions. Epithelial cells must be protected from constant TLR activation by commensals and their PAMP, in order for mucosal integrity to be maintained. The epithelial cells thus lack co-receptors like CD14 [6][7][8][9][10][11], and in addition, commensals have been suggested to actively suppress epithelia responses through NF-jB [12,13]. Yet, mucosal pathogens evoke rapid TLR4-dependent responses at mucosal sites, suggesting that alternative ligands and receptors might be involved in mucosal TLR activation. Pathogens use adhesive surface ligands to break the inertia of the mucosal barrier [14][15][16]. The innate defence is activated as a direct result of these interactions and epithelial cells produce the first wave of me...

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“…There is good evidence from a number of epidemiological studies that P fimbriae are important in upper UTI (Johnson, 1991). While the mechanism is debatable (Hedlund et al, 1999;Schilling et al, 2003), P-fimbrial expression has been shown to induce inflammation in humans and in a mouse model. A current model provides evidence for P-fimbrial adherence provoking inflammation in a cluster of differentiation number 14 (CD-14)-independent manner, probably by association with toll-like receptor number 4 (TLR-4) (Frendeus et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…There is good evidence from a number of epidemiological studies that P fimbriae are important in upper UTI (Johnson, 1991). While the mechanism is debatable (Hedlund et al, 1999;Schilling et al, 2003), P-fimbrial expression has been shown to induce inflammation in humans and in a mouse model. A current model provides evidence for P-fimbrial Abbreviations: GFP, green fluorescent protein; HA, haemagglutination; Lrp, leucine-responsive regulatory protein; MRHA, mannose-resistant HA; MSHA, mannose-sensitive HA; Pap, pyelonephritis-associated pili; Prf, Pap-related fimbriae; RBC, red blood cell; Sfa, S-fimbrial adhesin; UPEC, uropathogenic E. coli; UTI, urinary tract infection.…”

mentioning

confidence: 99%

Demonstration of regulatory cross-talk between P fimbriae and type 1 fimbriae in uropathogenic Escherichia coli

et al. 2006

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The majority of Escherichia coli strains isolated from urinary tract infections have the potential to express multiple fimbriae. Two of the most common fimbrial adhesins are type 1 fimbriae and pyelonephritis-associated pili (Pap). Previous research has shown that induced, plasmid-based expression of a Pap regulator, papB, and its close homologues can prevent inversion of the fim switch controlling the expression of type 1 fimbriae. The aim of the present study was to determine if this cross-regulation occurs when PapB is expressed from its native promoter in the chromosome of E. coli K-12 and clinical isolates. The regulation was examined in three ways: (1) mutated alleles of the pap regulatory region, including papB and papI, that maintain the pap promoter in either the off or the on phase were exchanged into the chromosome of both E. coli K-12 and the clinical isolate E. coli CFT073, and the effect on type 1 fimbrial expression was measured; (2) type 1 fimbrial expression was determined using a novel fimS : : gfp + reporter system in mutants of the clinical isolate E. coli 536 in which combinations of complete fimbrial clusters had been deleted; (3) type 1 fimbrial expression was determined in a range of clinical isolates and compared with both the number of P clusters and their expression. All three approaches demonstrated that P expression represses type 1 fimbrial expression. Using a number of novel genetic approaches, this work extends the initial finding that PapB inhibits FimB recombination to the impact of this regulation in clinical isolates. INTRODUCTIONUrinary tract infections (UTIs) are common, affecting a large proportion of the population. It is estimated that 20 % of women develop a UTI in their lifetime, and antibiotic treatment results in approximately 110 000 prescriptions per million inhabitants per annum in Europe (Naber, 2000). Escherichia coli strains are the predominant cause of uncomplicated UTIs, responsible for between 60 and 80 % of the cases reported in the UK each year (Graham & Galloway, 2001). Many infections are asymptomatic, especially in the elderly (Nicolle, 2001), but others result in cystitis. If the infection ascends to the kidney, then pyelonephritis can occur. Such infections are a significant origin of Gramnegative sepsis.Fimbrial adhesins are important virulence factors that allow binding of the bacteria to specific receptors on epithelial cells of the urinary tract. The two adhesins most commonly associated with UTI are type 1 fimbriae, and pyelonephritisassociated pili (Pap) and Pap-related fimbriae (Prf); the last two are collectively termed P fimbriae in this study. Type 1 fimbriae mediate binding to a-D-mannose-containing receptors and extracellular matrix components, whereas P fimbriae bind to glycoreceptors containing the aGal(1-4)bGal moiety (Lindberg et al., 1984). Although type 1 fimbriae are common to the majority of E. coli isolates, the FimH adhesin has been shown to be important in a mouse model of UTI, and a degranulation response to the fimbriae is asso...

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CD14- and Toll-Like Receptor-Dependent Activation of Bladder Epithelial Cells by Lipopolysaccharide and Type 1 PiliatedEscherichia coli

Cited by 136 publications

References 51 publications

Positive selection identifies an in vivo role for FimH during urinary tract infection in addition to mannose binding

Positive selection identifies an in vivo role for FimH during urinary tract infection in addition to mannose binding

Mechanism of pathogen‐specific TLR4 activation in the mucosa: Fimbriae, recognition receptors and adaptor protein selection

Demonstration of regulatory cross-talk between P fimbriae and type 1 fimbriae in uropathogenic Escherichia coli

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