Type 1 pilus-mediated bacterial invasion of bladder epithelial cells

Martínez, Juan José; Mulvey, Matthew A.; Schilling, Joel D.; Pinkner, Jerome S.; Hultgren, Scott J.

doi:10.1093/emboj/19.12.2803

Cited by 650 publications

(690 citation statements)

References 68 publications

(79 reference statements)

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“…In previous work, we used confocal microscopy to demonstrate that UPEC132 is an invasive uropathogen which can be internalized by human bladder epithelial cells [19]. A similar finding was reported for E. coli cystitis caused by isolate NU14 [20,21], suggesting that UPEC strains are intracellular bacteria. The invasion of host cells can allow pathogens to evade host defenses and ease their dissemination both within and across cellular barriers [22].…”

Section: Discussionsupporting

confidence: 68%

A novel gene R049 identified in uropathogenic Escherichia coli provides partial protection in mice from colonization

Chen

Zhang

et al. 2011

Chin. Sci. Bull.

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Uropathogenic Escherichia coli (UPEC) is the most common causative organism of human urinary tract infection (UTI). Several UPEC virulence factors have been identified, but more are yet to be found. We previously identified a novel 789-bp-long DNA fragment (named R049) in UPEC strain 132 using a suppressive subtractive hybridization technique. In the present study, we used genome walking to elongate the sequence of this fragment to obtain the whole gene sequence and examined the role of this gene product in generating protective immunity. Through bioinformatic analysis, we predicted that this gene is a 1311-bp open reading frame (ORF), which we designated ORF R049 (GenBank accession No.: EF488001). We further constructed a prokaryotic expression system to express full recombinant R049 protein and isolated and purified the protein through IPTG induction and nickel affinity chromatography. Using mouse immunosera generated by the purified protein, we confirmed the natural expression and outer membrane localization of the protein in wild-type strain UPEC132 by Western blotting. To test the potential of this protein as a vaccine candidate, we immunized mice with the recombinant protein before challenging them with UPEC132 through the urinary tract. The results showed significantly reduced bacterial colonization in the urine and kidneys of the immunization group compared with the control group. However, the degree of renal pathological damage was not significantly improved in the immunized mice. Our study has identified a novel gene of UPEC which can generate protective immunity against UTI. This novel gene provides a promising new vaccine candidate.

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Section: Discussionsupporting

confidence: 68%

A novel gene R049 identified in uropathogenic Escherichia coli provides partial protection in mice from colonization

Chen

Zhang

et al. 2011

Chin. Sci. Bull.

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“…Because UPEC act as opportunistic intracellular pathogens (Mulvey, 2002), we were interested whether host cell invasion was required for UPEC-mediated dephosphorylation of Akt S473. Type 1 pilus-mediated invasion of bladder epithelial cells by UPEC requires functional actin and microtubule cytoskeletal networks (unpublished data; Martinez et al, 2000). Treatment of 5637 cells with either the actin-disrupting drug cytochalasin D or the microtubule-disrupting agent nocodazole inhibit UPEC invasion, but neither drug prevented UTI89-mediated dephosphorylation of Akt S473 ( Figure 1B, right).…”

Section: Upec Stimulates Dephosphorylation Of Akt In Bladder Epithelimentioning

confidence: 88%

“…Both of these strains express filamentous adhesive organelles called type 1 pili (Blomfield et al, 1991;Langermann et al, 1997). These fibers mediate both bacterial adherence to and invasion of host epithelial cells, and they are major virulence factors encoded by virtually all UPEC isolates (Martinez et al, 2000). Akt activation status in infected 5637 cells was determined by Western blot analysis of host cell lysates by using antibodies to detect total Akt (specifically Akt1, which is the prominent Akt isoform found in bladder epithelial cells; unpublished observation) or activated Akt that has been phosphorylated at S473 (pAkt S473).…”

Section: Upec Stimulates Dephosphorylation Of Akt In Bladder Epithelimentioning

confidence: 99%

Inactivation of Host Akt/Protein Kinase B Signaling by Bacterial Pore-forming Toxins

Wiles

Dhakal

Eto

et al. 2008

MBoC

100

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Uropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections (UTIs), and they have the capacity to induce the death and exfoliation of target uroepithelial cells. This process can be facilitated by the pore-forming toxin ␣-hemolysin (HlyA), which is expressed and secreted by many UPEC isolates. Here, we demonstrate that HlyA can potently inhibit activation of Akt (protein kinase B), a key regulator of host cell survival, inflammatory responses, proliferation, and metabolism. HlyA ablates Akt activation via an extracellular calcium-dependent, potassium-independent process requiring HlyA insertion into the host plasma membrane and subsequent pore formation. Inhibitor studies indicate that Akt inactivation by HlyA involves aberrant stimulation of host protein phosphatases. We found that two other bacterial pore-forming toxins (aerolysin from Aeromonas species and ␣-toxin from Staphylococcus aureus) can also markedly attenuate Akt activation in a dose-dependent manner. These data suggest a novel mechanism by which sublytic concentrations of HlyA and other pore-forming toxins can modulate host cell survival and inflammatory pathways during the course of a bacterial infection. INTRODUCTIONStrains of uropathogenic Escherichia coli (UPEC) are the leading cause of urinary tract infections (UTIs), which currently rank among the most common of infectious diseases worldwide (Foxman, 2003;Marrs et al., 2005). During the course of an infection, UPEC can stimulate a number of antimicrobial, proinflammatory, prodifferentiation, proliferation, and host cell death pathways (Mulvey, 2002;Mysorekar et al., 2002). In some cases, UPEC can reportedly modulate these signaling events, causing attenuation of host inflammatory responses and potentiating host apoptotic cascades (Klumpp et al., 2001(Klumpp et al., , 2006Hunstad et al., 2005;Billips et al., 2007). These phenomena have been linked in part to the suppression of nuclear factor-B (NF B) activation and downstream signaling by unknown factors associated with UPEC (Klumpp et al., 2001;Hunstad et al., 2005). By hindering host cytokine expression and ensuing inflammatory responses, UPEC may be better able to establish itself and multiply within the cells and tissues of the urinary tract. At the same time, UPEC-induced death of bladder and renal epithelial cells can compromise mucosal barriers, and it may thereby facilitate bacterial dissemination and persistence within the urinary tract (Mulvey et al., 1998Chen et al., 2003a;Bower et al., 2005;Eto et al., 2006;Mansson et al., 2007b).A key regulator of host cell survival pathways is Akt (also known as protein kinase B, PKB; for recent reviews, see Fayard et al., 2005;Song et al., 2005;Manning and Cantley, 2007). This serine/threonine kinase is able to inhibit apoptosis, and it can help control cell cycle and metabolic pathways, endocytosis and vesicular trafficking, and host inflammatory responses, including the activation of NF B. Akt is activated downstream of phosphoinositide 3-kinase (PI3-kinase), which it...

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“…The mechanisms of interaction between UPECs and bladder epithelial cells have been extensively investigated (14,16,17). UPECs can also interact with renal tubule cells.…”

Section: Renal Collecting Duct Epithelial Cells React Tomentioning

confidence: 99%

Renal Collecting Duct Epithelial Cells React to Pyelonephritis-Associated Escherichia coli by Activating Distinct TLR4-Dependent and -Independent Inflammatory Pathways

Chassin

Goujon

Darche³

et al. 2006

The Journal of Immunology

117

156

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TLR4 plays a central role in resistance to pyelonephritis caused by uropathogenic Escherichia coli (UPEC). It has been suggested that renal tubule epithelial cells expressing TLRs may play a key role in inflammatory disorders and in initiating host defenses. In this study we used an experimental mouse model of ascending urinary tract infection to show that UPEC isolates preferentially adhered to the apical surface of medullary collecting duct (MCD) intercalated cells. UPEC-infected C3H/HeJ (Lpsd) mice carrying an inactivating mutation of tlr4 failed to clear renal bacteria and exhibited a dramatic slump in proinflammatory mediators as compared with infected wild-type C3H/HeOuJ (Lpsn) mice. However, the level of expression of the leukocyte chemoattractants MIP-2 and TNF-α still remained greater in UPEC-infected than in naive C3H/HeJ (Lpsd) mice. Using primary cultures of microdissected Lpsn MCDs that expressed TLR4 and its accessory molecules MD2, MyD88, and CD14, we also show that UPECs stimulated both a TLR4-mediated, MyD88-dependent, TIR domain-containing adaptor-inducing IFN-β-independent pathway and a TLR4-independent pathway, leading to bipolarized secretion of MIP-2. Stimulation by UPECs of the TLR4-mediated pathway in Lpsn MCDs leads to the activation of NF-κB, and MAPK p38, ERK1/2, and JNK. In addition, UPECs stimulated TLR4-independent signaling by activating a TNF receptor-associated factor 2-apoptosis signal-regulatory kinase 1-JNK pathway. These findings demonstrate that epithelial collecting duct cells are actively involved in the initiation of an immune response via several distinct signaling pathways and suggest that intercalated cells play an active role in the recognition of UPECs colonizing the kidneys.

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Type 1 pilus-mediated bacterial invasion of bladder epithelial cells

Cited by 650 publications

References 68 publications

A novel gene R049 identified in uropathogenic Escherichia coli provides partial protection in mice from colonization

A novel gene R049 identified in uropathogenic Escherichia coli provides partial protection in mice from colonization

Inactivation of Host Akt/Protein Kinase B Signaling by Bacterial Pore-forming Toxins

Renal Collecting Duct Epithelial Cells React to Pyelonephritis-Associated Escherichia coli by Activating Distinct TLR4-Dependent and -Independent Inflammatory Pathways

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