Experimental Urinary Tract Infection Research Articles

Human Ribonuclease 6 Has a Protective Role during Experimental Urinary Tract Infection

Mounting evidence suggests that antimicrobial peptides and proteins (AMPs) belonging to the RNase A superfamily have a critical role in defending the bladder and kidney from bacterial infection. RNase 6 has been identified as a potent, leukocyte-derived AMP, but its impact on urinary tract infection (UTI) in vivo has not been demonstrated. To test the functional role of human RNase 6, we generated RNASE6 transgenic mice and studied their susceptibility to experimental UTI. In addition, we generated bone marrow-derived macrophages to study the impact of RNase 6 on antimicrobial activity within a cellular context. When subjected to experimental UTI, RNASE6 transgenic mice developed reduced uropathogenic Escherichia coli (UPEC) burden, mucosal injury, and inflammation compared to non-transgenic controls. Monocytes and macrophages were the predominant cellular sources of RNase 6 during UTI, and RNASE6 transgenic macrophages were more proficient at intracellular UPEC killing than non-transgenic controls. Altogether, our findings indicate a protective role for human RNase 6 during experimental UTI.

Neutrophil NOX2 is Required to Control Experimental Urinary Tract Infection

Abstract Urinary tract infections (UTIs) affect 150 million people worldwide. Uropathogenic Escherichia coli (UPEC) is the primary pathogen causing over 80% of UTIs. Systemic antibiotic treatment is the only available therapy for UTIs. Thus, novel non-antibiotic treatments for UTI are necessary. The NADPH oxidase complex 2 (NOX2) has an essential role in the antimicrobial response against many bacterial and fungal infections, but its role during UTIs remains unknown. Objective To study the role of NOX2 in bacterial killing during experimental UTI. Methods Female wild-type (WT) C57BL/6 mice, NOX2 knockout (KO) mice, and WT mice treated with a NOX2 inhibitor were transurethrally infected with UPEC (CFT073 strain). NOX2 protein expression was analyzed by Western blotting. Cellular sources of NOX2 were identified by immunofluorescence. Neutrophils were isolated from murine bone marrow. Human neutrophils were purified from peripheral blood of healthy donors. Purified neutrophils were infected with UPEC in vitro. UPEC burden was assessed by enumerating colony forming units (CFU). Reactive oxygen species (ROS) production was quantified using the Amplex™ Red kit. Results NOX2 KO mice, or mice treated with NOX2 inhibitor, were more susceptible to experimental UTI compared to WT mice. Immunofluorescence microscopy localized NOX2 primarily in infiltrating neutrophils. Neutrophils from NOX2 KO mice exhibited impaired extracellular ROS production and increased intracellular bacteria compared to WT controls, after challenged with UPEC in vitro. Similar effects occurred in human and murine neutrophils following chemical inhibition of NOX2 in vitro. Conclusion Neutrophil NOX2 serves a critical antimicrobial role during experimental UTI. Supported by grant from NIH (K01 DK128379-01)

Silk Fibroin Nanoadjuvant as a Promising Vaccine Carrier to Deliver the FimH-IutA Antigen for Urinary Tract Infection.

In this study, the silk fibroin nanoparticle (SFNP) was used as a nanoadjuvant in combination with a multiepitope-based vaccine for urinary tract infection (UTI). Nanoparticles containing the fusion protein were analyzed for physicochemical properties, toxicity, release profile, and in vivo potency. The synthesized nanovaccine showed a spherical shape with a mean particle size of 180 nm and an encapsulation efficiency of 88%. Antigen release from SFNPs was 18% after 42 days. The SFNPs showed a zeta potential of -29 mV and had no toxic effect on the L929 cells in vitro. SFNPs in the vaccine formulations promoted humoral and cellular (IFN-γ, IL-4, and IL-17) immune responses in comparison to controls. Immunization of mice with antigen-encapsulated SFNPs significantly increased the total IgG as well as IgG2a/IgG1 ratio. In addition, this formulation triggered concurrently type 1 (Th1) and type 2 (Th2) immune responses, with a Th1-polarized response. Furthermore, highly effective protection of the bladder and kidney against experimental UTI was obtained by using the nanoadjuvant containing the antigen for 6 months. The results demonstrated that SFNPs can be proposed as potent adjuvants or vaccine carriers to develop new and more effective nanovaccine formulations in the future.

MP46-01 DEFICIENCY OF HOST MICROBIOME BY ANTIBIOTIC EXPOSURE COMPROMISES INNATE IMMUNE RESPONSES OF THE URINARY BLADDER AGAINST UROPATHOGENIC E. COLI

You have accessJournal of UrologyInfections/Inflammation/Cystic Disease of the Genitourinary Tract: Kidney & Bladder I (MP46)1 Apr 2020MP46-01 DEFICIENCY OF HOST MICROBIOME BY ANTIBIOTIC EXPOSURE COMPROMISES INNATE IMMUNE RESPONSES OF THE URINARY BLADDER AGAINST UROPATHOGENIC E. COLI Yan Liu, Abbey Lepor, Hongying Huang, Herbert Lepor, Xue-Ru Wu, and Ellen Shapiro* Yan LiuYan Liu More articles by this author , Abbey LeporAbbey Lepor More articles by this author , Hongying HuangHongying Huang More articles by this author , Herbert LeporHerbert Lepor More articles by this author , Xue-Ru WuXue-Ru Wu More articles by this author , and Ellen Shapiro*Ellen Shapiro* More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000901.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Host microbiome is critical for maintaining immune homeostasis and priming systemic and local immune responses. Little is known about whether microbiome perturbation affects innate responses of the bladder against infections caused by uropathogenic E. coli (UPEC). A recent population-based study showed a link between antibiotic use, gut microbiome perturbation and recurrent urinary tract infection (UTI). This study was to explore the effects of antibiotic-induced host microbiome perturbation on experimental UTI. METHODS: Antibiotic (Abx) treatment (1 g/L each of ampicillin, neomycin, metronidazole, 0.5 g/L of vancomycin in drinking water) started for conventionally raised female mouse breeders (129/SvEv strain), continued during pregnancy until after weaning of the offspring which were treated for 2 more weeks. Treatment ceased 10 days before UPEC infection. Control mice received no Abx. Due to technical difficulties to quantify urine microbiome in mice, fecal microbiome was used as a surrogate by Q-PCR and 16S-rDNA MiSeq. Female mice (n=15) were transurethrally infected with UPEC strain UTI89 (107 cfu in 50 ul). Bladders were homogenized/plated to enumerate UPEC or immunostained with anti-E.coli, uroplakin Ia, p65 of NF-kB and Ly6G. Neutrophil infiltration was assessed by myeloperoxidase (MPO) assay. RESULTS: Abx treatment resulted in a 90% reduction of fecal microbiome and its diversity by 34% but it did not affect urinary tract anatomy, urothelial morphology or apical distribution of uroplakin Ia – the urothelial receptor for type 1-piliated UPEC. UPEC induced rapid activation of NF-kB in the umbrella cells in both the Abx-treated and control mice at 2 hours post-infection (hpi). However, bacterial colonization at 24 hpi was 5-fold higher in the Abx-treated mouse bladders than the controls. The number of intracellular bacterial communities at 12 and 24 hpi was 2.5-fold and 5-folder higher, respectively, in the Abx mice than in controls. In contrast, neutrophil infiltration and neutrophil MPO activity were significantly lower in the Abx mice. CONCLUSIONS: Our study provides the first experimental evidence demonstrating that the host microbiome plays a critical role in innate immune defenses against UTI and that its deficiency caused by early-age antibiotic exposure leads to compromised neutrophil infiltration and increased bacterial burden in the bladder. Further studies are needed to ascertain whether these effects are caused by gut and/or urinary microbiome. Source of Funding: None © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e673-e673 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Yan Liu More articles by this author Abbey Lepor More articles by this author Hongying Huang More articles by this author Herbert Lepor More articles by this author Xue-Ru Wu More articles by this author Ellen Shapiro* More articles by this author Expand All Advertisement PDF downloadLoading ...

The oxidative fumarase FumC is a key contributor for E. coli fitness under iron-limitation and during UTI

The energy required for a bacterium to grow and colonize the host is generated by metabolic and respiratory functions of the cell. Proton motive force, produced by these processes, drives cellular mechanisms including redox balance, membrane potential, motility, acid resistance, and the import and export of substrates. Previously, disruption of succinate dehydrogenase (sdhB) and fumarate reductase (frdA) within the oxidative and reductive tricarboxylic acid (TCA) pathways in uropathogenic E. coli (UPEC) CFT073 indicated that the oxidative, but not the reductive TCA pathway, is required for fitness in the urinary tract. Those findings led to the hypothesis that fumA and fumC encoding fumarase enzymes of the oxidative TCA cycle would be required for UPEC colonization, while fumB of the reductive TCA pathway would be dispensable. However, only UPEC strains lacking fumC had a fitness defect during experimental urinary tract infection (UTI). To further characterize the role of respiration in UPEC during UTI, additional mutants disrupting both the oxidative and reductive TCA pathways were constructed. We found that knock-out of frdA in the sdhB mutant strain background ameliorated the fitness defect observed in the bladder and kidneys for the sdhB mutant strain and results in a fitness advantage in the bladder during experimental UTI. The fitness defect was restored in the sdhBfrdA double mutant by complementation with frdABCD. Taken together, we demonstrate that it is not the oxidative or reductive pathway that is important for UPEC fitness per se, but rather only the oxidative TCA enzyme FumC. This fumarase lacks an iron-sulfur cluster and is required for UPEC fitness during UTI, most likely acting as a counter measure against exogenous stressors, especially in the iron-limited bladder niche.

Nitrate Metabolism Modulates Biosynthesis of Biofilm Components in Uropathogenic Escherichia coli and Acts as a Fitness Factor During Experimental Urinary Tract Infection.

To successfully colonize a variety of environments, bacteria can coordinate complex collective behaviors such as biofilm formation. To thrive in oxygen limited niches, bacteria’s versatile physiology enables the utilization of alternative electron acceptors. Nitrate, the second most favorable electron acceptor after oxygen, plays a prominent role in the physiology of uropathogenic Escherichia coli (UPEC) and is abundantly found in urine. Here we analyzed the role of extracellular nitrate in the pathogenesis of the UPEC strain CFT073 with an initial focus on biofilm formation. Colony morphotyping in combination with extensive mutational, transcriptional, and protein expression analyses of CFT073 wild-type and mutants deficient in one or several nitrate reductases revealed an association between nitrate reduction and the biosynthesis of biofilm extracellular matrix components. We identified a role for the nitrate response regulator NarL in modulating expression of the biofilm master regulator CsgD. To analyze the role of nitrate reduction during infection in vivo, we tested wild-type CFT073 and a nitrate reductase null mutant in an ascending urinary tract infection (UTI) model. Individually, each strain colonized extensively, suggesting that nitrate reduction is expendable during UTI. However, during competitive co-infection, the strain incapable of nitrate reduction was strongly outcompeted. This suggests that nitrate reduction can be considered a non-essential but advantageous fitness factor for UPEC pathogenesis. This implies that UPEC rapidly adapts their metabolic needs to the microenvironment of infected tissue. Collectively, this work demonstrates a unique association between nitrate respiration, biofilm formation, and UPEC pathogenicity, highlighting how the use of alternative electron acceptors enables bacterial pathogens to adapt to challenging infectious microenvironments.

Étude de la virulence d’Acinetobacter baumannii dans un modèle d’infection expérimental du tractus urinaire

The virulence characteristics of Acinetobacter baumannii are poorly understood, especially the in vivo pathogenicity in the urinary tract.This research evaluates the degree of virulence of urinary strain of A. baumannii by visualizing the histopathological features in an experimental urinary tract infection. The infectious effects of this isolate on mice bladder and kidneys were compared to the effects of a Proteus mirabilis specie.The in vivo study was carried out by experimental induction of an ascending infection in mice and visualizing the effects on urinary organs. An ascending model of pyelonephritis was established in female mice with the test isolates. Quantitative bacterial counts and histopathological evaluations of mouse bladders and renal tissues were performed.A. baumannii was able to colonize the bladder and renal tissue of mice. Microscopic observations of the bladder urothelium and renal tissue revealed significant inflammatory changes in infected mice. Furthermore, these inflammatory effects are quite similar to those previously reported with other urinary bacteria. This induced pyelonephritis model might be considered as a promoter to understand the pathogenicity of A. baumannii.The identification of virulence factors could contribute to the development of novel therapeutic alternatives for A. baumannii infections.

NLRX1 is not involved in the host defense against Escherichia coli induced pyelonephritis

Background: Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (E. coli) are one of the most prominent infections that have serious impact on kidney functioning and the development of chronic kidney disease. NOD-like receptor (NLR)X1 is an innate immune receptor that is important for immune metabolism and regulation, with as yet an unknown role in UTI and the pathophysiology of pyelonephritis. Methods: Wild-type (WT) and NLRX1 Knock-out (KO) female mice were subjected to UTI by intravesically inoculation of uropathogenic E. coli and sacrificed at 24h and 48h after infection after which bacterial burden and the inflammatory response in the bladder and kidney were studied. Ex  vivo we studied the role of NLRX1 during the LPS induced pro-inflammatory cytokine response and phagocytosis of E. coli by granulocytes and monocytes. Results: Here, we report that during early experimental UTI NLRX1 absence reduces bacterial clearance in the bladder and dampens the inflammatory cytokine response, whereas in the kidney NLRX1 does not affect bacterial burden or cytokine response. In addition, we found that NLRX1 is not essential for the pro-inflammatory cytokine secretion by granulocytes and monocytes in response to LPS nor for bacterial phagocytosis. Conclusion: Together, we report that NLRX1 is important in enhancing the early host defense against uropathogenic E. coli in the bladder but does not affect the development of pyelonephritis.

Ribonuclease 7 Shields the Kidney and Bladder from Invasive Uropathogenic Escherichia coli Infection.

Evidence suggests that antimicrobial peptides, components of the innate immune response, protect the kidneys and bladder from bacterial challenge. We previously identified ribonuclease 7 (RNase 7) as a human antimicrobial peptide that has bactericidal activity against uropathogenic Escherichia coli (UPEC). Functional studies assessing RNase 7's contributions to urinary tract defense are limited. To investigate RNase 7's role in preventing urinary tract infection (UTI), we quantified urinary RNase 7 concentrations in 29 girls and adolescents with a UTI history and 29 healthy female human controls. To assess RNase 7's antimicrobial activity in vitro in human urothelial cells, we used siRNA to silence urothelial RNase 7 production and retroviral constructs to stably overexpress RNase 7; we then evaluated UPEC's ability to bind and invade these cells. For RNase 7 in vivo studies, we developed humanized RNase 7 transgenic mice, subjected them to experimental UTI, and enumerated UPEC burden in the urine, bladder, and kidneys. Compared with controls, study participants with a UTI history had 1.5-fold lower urinary RNase 7 concentrations. When RNase 7 was silenced in vitro, the percentage of UPEC binding or invading human urothelial cells increased; when cells overexpressed RNase 7, UPEC attachment and invasion decreased. In the transgenic mice, we detected RNase 7 expression in the kidney's intercalated cells and bladder urothelium. RNase 7 humanized mice exhibited marked protection from UPEC. These findings provide evidence that RNase 7 has a role in kidney and bladder host defense against UPEC and establish a foundation for investigating RNase 7 as a UTI prognostic marker or nonantibiotic-based therapy.

NLRX1 is not involved in the host defense against Escherichia coli induced pyelonephritis

Background: Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (E. coli) are one of the most prominent infections that have serious impact on kidney functioning and the development of chronic kidney disease. NOD-like receptor (NLR)X1 is an innate immune receptor that is important for immune metabolism and regulation, with as yet an unknown role in UTI and the pathophysiology of pyelonephritis. Methods: Wild-type (WT) and NLRX1 Knock-out (KO) female mice were subjected to UTI by intravesically inoculation of uropathogenic E. coli and sacrificed at 24h and 48h after infection after which bacterial burden and the inflammatory response in the bladder and kidney were studied. Ex  vivo we studied the role of NLRX1 during the LPS induced pro-inflammatory cytokine response and phagocytosis of E. coli by granulocytes and monocytes. Results: Here, we report that during early experimental UTI NLRX1 absence reduces bacterial clearance in the bladder and dampens the inflammatory cytokine response, whereas in the kidney NLRX1 does not affect bacterial burden or cytokine response. In addition, we found that NLRX1 is not essential for the pro-inflammatory cytokine secretion by granulocytes and monocytes in response to LPS nor for bacterial phagocytosis. Conclusion: Together, we report that NLRX1 is important in enhancing the early host defense against uropathogenic E. coli in the bladder but does not affect the development of pyelonephritis.

Calcineurin inhibitor Tacrolimus impairs host immune response against urinary tract infection

Calcineurin inhibitor Tacrolimus, is a potent immunosuppressive drug widely used in order to prevent acute graft rejection. Urinary tract infection (UTI) is the most frequent infectious complication in renal transplant patients and long-term use of Tacrolimus might be involved in higher susceptibility to bacterial infections. It remains largely unknown how Tacrolimus affects the host innate immune response against lower and upper UTI. To address this issue, we used experimental UTI model by intravesical inoculation of uropathogenic E.coli in female wild-type mice pre-treated with Tacrolimus or solvent (CTR). We found that Tacrolimus pre-treated mice displayed higher bacterial loads (cystitis, pyelonephritis and bacteremia) than CTR mice. Granulocytes from Tacrolimus pre-treated mice phagocytized less E. coli, released less MPO and expressed decreased levels of CXCR2 receptor upon infection. Moreover, Tacrolimus reduced TLR5 expression in bladder macrophages during UTI. This immunosuppressive state can be explained by the upregulation of TLR-signaling negative regulators (A20, ATF3, IRAK-M and SOCS1) and parallel downregulation of TLR5 as observed in Tacrolimus treated granulocytes and macrophages. We conclude that Tacrolimus impairs host innate immune responses against UTI.

Novel role for androgen signaling in pyelonephritis

Sex differences in urinary tract infection (UTI) susceptibility and severity are known, but have historically focused on anatomic differences between males and females. Until recently, experimental UTI has been limited to female animals due to ease of transurethral bladder catheterization. Olson and colleagues have developed a model of experimental UTI independent of sex that relies on direct bladder inoculation and thus permits investigation of sex differences in UTI susceptibility. They now build upon their prior work in this model by implicating androgens as drivers of tubular invasion by uropathogenic Escherichia coli, which form luminal bacterial communities preceding renal abscess formation.

NLRX1 is not involved in the host defense against Escherichia coli induced pyelonephritis

Background: Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (E. coli) are one of the most prominent infections that have serious impact on kidney functioning and the development of chronic kidney disease. NOD-like receptor (NLR)X1 is an innate immune receptor that is important for immune metabolism and regulation, with as yet an unknown role in UTI and the pathophysiology of pyelonephritis. Methods: Wild-type (WT) and NLRX1 Knock-out (KO) female mice were subjected to UTI by intravesically inoculation of uropathogenic E. coli and sacrificed at 24h and 48h after infection after which bacterial burden and the inflammatory response in the bladder and kidney were studied. Ex  vivo we studied the role of NLRX1 during the LPS induced pro-inflammatory cytokine response and phagocytosis of E. coli by granulocytes and monocytes. Results: Here, we report that during early experimental UTI NLRX1 absence reduces bacterial clearance in the bladder and dampens the inflammatory cytokine response, whereas in the kidney NLRX1 does not affect bacterial burden or cytokine response. In addition, we found that NLRX1 is not essential for the pro-inflammatory cytokine secretion by granulocytes and monocytes in response to LPS nor for bacterial phagocytosis. Conclusion: Together, we report that NLRX1 is important in enhancing the early host defense against uropathogenic E. coli in the bladder but does not affect the development of pyelonephritis.

Purification of Intracellular Bacterial Communities during Experimental Urinary Tract Infection Reveals an Abundant and Viable Bacterial Reservoir.

Urinary tract infections (UTIs) are a major infection of humans, particularly affecting women. Recurrent UTIs can cause significant discomfort and expose patients to high levels of antibiotic use, which in turn contributes to the development of higher antibiotic resistance rates. Most UTIs are caused by uropathogenic Escherichia coli, which is able to form intracellular collections (termed intracellular bacterial communities [IBCs]) within the epithelial cells lining the bladder lumen. IBCs are seen in both infected mice and humans and are a potential cause of recurrent UTI. Genetic and molecular studies of IBCs have been hampered both by the low number of bacteria in IBCs relative to the number extracellular bacteria and by population bottlenecks that occur during IBC formation. We now report the development of a simple and rapid technique for isolating pure IBCs from experimentally infected mice. We verified the specificity and purity of the isolated IBCs via microscopy, gene expression, and culture-based methods. Our results further demonstrated that our isolation technique practically enables specific molecular studies of IBCs. In the first such direct measurement, we determined that a single epithelial cell containing an early IBC typically contains 103 viable bacteria. Our isolation technique complements recent progress in low-input, single-cell genomics to enable future genomic studies of the formation of IBCs and their activation pathways during recurrent UTI, which may lead to novel strategies to eliminate them from the bladder.

A novel multi-peptide subunit vaccine admixed with AddaVax adjuvant produces significant immunogenicity and protection against Proteus mirabilis urinary tract infection in mice model

Proteus mirabilis is a common pathogen in urinary tract infections (UTIs). There is no vaccine against P. mirabilis, thus a novel multi-peptide vaccine of MrpA, UcaA and Pta factors of P. mirabilis we designed and a mice model was used to evaluate its efficacy in combination with AddaVax adjuvant. According to the bioinformatics studies, 7 fragments of MrpA (31–75, 112–146), UcaA (68–117, 132–156) and Pta (210–265, 340–400, 496–570) with B and T cell epitope regions were selected for fusion construction. Mice subcutaneously vaccinated with the fusion MrpA.Pta.UcaA induced a significant increase in serum and mucosal IgG and IgA responses. The fusion also showed a significant induction in cellular responses (Th1 and Th2). The addition of AddaVax to fusion and the mixture of MrpA, UcaA, and Pta (MUP) improved the humoral and cellular responses, especially the IgG2a and IFN-γ (Th1 responses) levels. Fusion with and without AddaVax and MUP + AddaVax could maintain significant humoral responses until 6 months after the first vaccine dose. All vaccine combinations with and without adjuvant showed high effectiveness in the protection of the bladder and kidney against experimental UTI; this could be attributed to the significant humoral and cellular responses. The present study suggests that the AddaVax-based vaccine formulations especially the fusion Pta.MrpA.UcaA admixed with AddaVax as potential vaccine candidates for protection against P. mirabilis. Furthermore, AddaVax could be considered as an effective adjuvant in designing other vaccines against UTI pathogens.

Evaluation of prevalence, immunogenicity and efficacy of FyuA iron receptor in uropathogenic Escherichia coli isolates as a vaccine target against urinary tract infection

Uropathogenic Escherichia coli (UPEC) are among the most prevalent agents of urinary tract infections (UTIs). Antibiotic resistance reaches the need for alternative treatment approaches such as vaccination against UTIs. There is no ideal vaccine against UTIs, thus there is a need to evaluate different targets of uropathogens against UTIs. Ferric scavenger receptor FyuA in UPEC has the properties of an ideal vaccine candidate against UTIs. In the present study, the prevalence of FyuA among UPEC isolates, its immunogenicity with and without alum adjuvant, and its efficacy against experimental UTI were assessed. Totally, fyuA gene was present in 77% of the UPEC isolates tested. Alignments of FyuA exhibited a high degree of conservation among different submitted UPEC isolates in GenBank. The bioinformatics studies showed the high confidence value and stability of the FyuA structure. SDS-PAGE and Western blot confirmed the purification of FyuA with high yield by nickel resins. Mice vaccinated subcutaneously with the FyuA induced a significantly higher humoral response (total IgG, IgG1 and IgG2a) than control mice that alum enhanced these responses. The FuyA alone showed the ability to reduce the colonization of UPEC in bladder and kidney of mice as compared to the control group. But the addition of alum to FyuA increased the protection level against UPEC in these organs. Since, FyuA induced significant IgG1 (Th2) and IgG2a (Th1) responses and protected the mice against experimental UTI, it could be a promising target against UPEC infections.

Cranberry Juice and Combinations of Its Organic Acids Are Effective against Experimental Urinary Tract Infection.

The antibacterial effect of cranberry juice and the organic acids therein on infection by uropathogenic Escherichia coli was studied in an experimental mouse model of urinary tract infection (UTI). Reduced bacterial counts were found in the bladder (P < 0.01) of mice drinking fresh cranberry juice. Commercially available cranberry juice cocktail also significantly reduced (P < 0.01) bacterial populations in the bladder, as did the hydrophilic fraction of cranberry juice (P < 0.05). Quinic, malic, shikimic, and citric acid, the preponderant organic acids in cranberry juice, were tested in combination and individually. The four organic acids also decreased bacterial levels in the bladder when administered together (P < 0.001), and so did the combination of malic plus citric acid (P < 0.01) and malic plus quinic acid (P < 0.05). The other tested combinations of the organic acids, and the acids administered singly, did not have any effect in the UTI model. Apparently, the antibacterial effect of the organic acids from cranberry juice on UTI can be obtained by administering a combination of malic acid and either citric or quinic acid. This study show for the first time that cranberry juice reduce E. coli colonization of the bladder in an experimental mouse model of urinary tract infection and that the organic acids are active agents.

PD12-02 ANTIMICROBIAL GENE EXPRESSION AND UTI SUSCEPTIBILITY IS DEPENDENT ON IL-6/STAT3 SIGNALING

You have accessJournal of UrologyInfections/Inflammation/Cystic Disease of the Genitourinary Tract: Kidney & Bladder I1 Apr 2017PD12-02 ANTIMICROBIAL GENE EXPRESSION AND UTI SUSCEPTIBILITY IS DEPENDENT ON IL-6/STAT3 SIGNALING Christina Ching, Sudipti Gupta, Birong Li, and Brian Becknell Christina ChingChristina Ching More articles by this author , Sudipti GuptaSudipti Gupta More articles by this author , Birong LiBirong Li More articles by this author , and Brian BecknellBrian Becknell More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.677AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Urinary tract infections (UTI) are a significant source of morbidity. Due to rising antibiotic resistance patterns, alternate treatments are needed. Prior work has demonstrated induction of urine and serum IL-6 in pyelonephritis and renal scarring. IL-6 has been linked to antimicrobial peptide (AMP) production in other organs via Stat3 phosphorylation on Tyr705. As a result, we sought to evaluate the potential role of IL-6/Stat3 induced signaling on urothelial AMP expression and UTI susceptibility. METHODS We infected 6 week old female C57BL/6J or C3H/HeOuJ mice transurethrally with UPEC and measured IL-6, phosphorylated (p-)Stat3, and AMP expression by ELISA, qRT-PCR, Western blotting, and immunofluorescence microscopy. The requirement for Lipopolysaccharide (Lps) / Toll-like receptor 4 (Tlr4) signaling was established using Lps-hyporesponsive C3H/HeJ mice, compared to C3H/HeOuJ Lps-sensitive controls. We evaluated the roles of IL-6 in p-Stat3, AMP production, and UPEC clearance using IL-6 neutralizing antibody and IL-6 knock out (KO) mice. We determined the contribution of Stat3 to AMP production via tamoxifen-inducible Stat3 conditional KO mice. We measured bacterial burden by serial plating on LB agar. Results were evaluated by Mann-Whitney U test with p <0.05 being significant. RESULTS Upon UPEC infection, we observed a time dependent induction of urinary IL-6 secretion and bladder p-Stat3. Sustained expression of IL-6 and p-Stat3 required intact Tlr4 signaling. P-Stat3 localized to the nuclei of infected bladder urothelium. Bladder AMP mRNA levels increased following peak IL-6 secretion and p-Stat3. IL-6 KO mice exhibited absent urothelial p-Stat3 and severely blunted AMP mRNA induction following experimental UTI, leading to impaired UPEC clearance. Conversely, intraperitoneal administration of recombinant IL-6 induced bladder p-Stat3 and AMP expression in the absence of infection. Conditional Stat3 deletion reduced bladder AMP mRNA levels at baseline and following experimental UTI. IL-6 neutralizing antibody reduced p-Stat3 levels in C3H/HeOuJ mice, with increased renal UPEC colonization and pyelonephritis severity. CONCLUSIONS IL-6 is both necessary and sufficient for urothelial p-Stat3 and AMP transcription, and genetic or acquired IL-6 deficiency leads to increased UTI susceptibility. This implicates IL-6 and Stat3 as master regulators of urothelial AMP transcription in states of sterility and infection. Therapeutic manipulation of the IL-6/Stat3 axis provides a mechanism to alter AMP expression to treat and even prevent UTI. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e265-e266 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Christina Ching More articles by this author Sudipti Gupta More articles by this author Birong Li More articles by this author Brian Becknell More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Copper Is a Host Effector Mobilized to Urine during Urinary Tract Infection To Impair Bacterial Colonization.

Urinary tract infection (UTI) is a major global infectious disease affecting millions of people annually. Human urinary copper (Cu) content is elevated during UTI caused by uropathogenic Escherichia coli (UPEC). UPEC upregulates the expression of Cu efflux genes during clinical UTI in patients as an adaptive response to host-derived Cu. Whether Cu is mobilized to urine as a host response to UTI and its role in protection against UTI remain unresolved. To address these questions, we tested the hypothesis that Cu is a host effector mobilized to urine during UTI to limit bacterial growth. Our results reveal that Cu is mobilized to urine during UTI caused by the major uropathogens Proteus mirabilis and Klebsiella pneumoniae, in addition to UPEC, in humans. Ceruloplasmin, a Cu-containing ferroxidase, is found at higher levels in UTI urine than in healthy control urine and serves as the molecular source of urinary Cu during UTI. Our results demonstrate that ceruloplasmin decreases the bioavailability of iron in urine by a transferrin-dependent mechanism. Experimental UTI with UPEC in nonhuman primates recapitulates the increased urinary Cu content observed during clinical UTI. Furthermore, Cu-deficient mice are highly colonized by UPEC, indicating that Cu is involved in the limiting of bacterial growth within the urinary tract. Collectively, our results indicate that Cu is a host effector that is involved in protection against pathogen colonization of the urinary tract. Because urinary Cu levels are amenable to modulation, augmentation of the Cu-based host defense against UTI represents a novel approach to limiting bacterial colonization during UTI.

Rhl quorum sensing affects the virulence potential of Pseudomonas aeruginosa in an experimental urinary tract infection

Pseudomonas aeruginosa quorum sensing systems (QSS) las, rhl and PQS play a significant role in pathogenicity. Although multiple studies have explored the role of the las QSS in various types of infections, including urinary tract infections (UTIs), the role of the rhl QSS is still poorly understood. In this study, an attempt was made to explore the role of the rhl QSS in the pathogenesis of UTI. The wild-type strain P. aeruginosa PAO1 and its isogenic rhl QSS mutant strains, PDO-100 and PDO-111, were used. Strains were studied for the expression of extra-cellular virulence factors and the ability to induce experimental UTI in a mouse model. Evaluation was based on in vitro estimation of virulence factors (elastase, protease, rhamnolipid) and in vivo bacteriological and histopathological analysis of renal and bladder tissue. The cytokine levels were determined in the renal tissue of infected mice. Wild-type PAO1 showed the highest level of virulence traits. The tissue bacteriology and histopathology were indicative of establishment of UTI. The level of inflammatory cytokines was consistent with the bacteriology and pathology results. The rhl QSS mutant strains showed significantly reduced pathogenicity. On supplementation with C4-homoserine lactone, strain PDO-100 showed a significant increase in pathogenicity. The results indicate that the rhl QSS affects the virulence potential of P. aeruginosa and that, despite the presence of the las QSS, mutant strains exhibited reduced pathology. Therefore, the rhl QSS may be exploited in more detail for future drug intervention tactics.