Serum and urine levels of interleukin-6 and interleukin-8 in children with acute pyelonephritis

Urinary tract infection (UTI) is a common clinical disorder in younger infants and children and may result in permanent renal damage. The inflammatory cytokines interleukin (IL)-6 and IL-8 play an important role in response to bacterial infection. This prospective study investigated the association between serum and urine IL-6 and IL-8 levels and acute pyelonephritis confirmed by (99m)Tc-dimercaptosuccinic acid (DMSA) scan. A total of 78 children aged 1-121 months with a diagnosis of first-time febrile UTI were included. The following inflammatory markers were assessed: fever; white blood cells count (WBC); C-reactive protein (CRP); and serum and urine IL-6 and IL-8. The patients were divided into the acute pyelonephritis group (n=42) and the lower UTI group (n=36) according to the results of DMSA scan. Fever, WBC and CRP levels were significantly higher in children with acute pyelonephritis than in those with lower UTI (all p <0.001). Significantly, higher initial serum and urine IL-6 and IL-8 levels were found in children with acute pyelonephritis than in those with lower UTI (all p <0.001). Serum and urine IL-6 in children with acute pyelonephritis were positively correlated with fever, CRP and leucocyturia. These results indicate that both serum and urine IL-6 and IL-8 levels, particularly IL-6, are useful diagnostic tools for early recognition of acute pyelonephritis in febrile children.     

Establishment and Characterization of UTI and CAUTI in a Mouse Model

Urinary tract infections (UTI) are highly prevalent, a significant cause of morbidity and are increasingly resistant to treatment with antibiotics. Females are disproportionately afflicted by UTI: 50% of all women will have a UTI in their lifetime. Additionally, 20-40% of these women who have an initial UTI will suffer a recurrence with some suffering frequent recurrences with serious deterioration in the quality of life, pain and discomfort, disruption of daily activities, increased healthcare costs, and few treatment options other than long-term antibiotic prophylaxis. Uropathogenic Escherichia coli (UPEC) is the primary causative agent of community acquired UTI. Catheter-associated UTI (CAUTI) is the most common hospital acquired infection accounting for a million occurrences in the US annually and dramatic healthcare costs. While UPEC is also the primary cause of CAUTI, other causative agents are of increased significance including Enterococcus faecalis. Here we utilize two well-established mouse models that recapitulate many of the clinical characteristics of these human diseases. For UTI, a C3H/HeN model recapitulates many of the features of UPEC virulence observed in humans including host responses, IBC formation and filamentation. For CAUTI, a model using C57BL/6 mice, which retain catheter bladder implants, has been shown to be susceptible to E. faecalis bladder infection. These representative models are being used to gain striking new insights into the pathogenesis of UTI disease, which is leading to the development of novel therapeutics and management or prevention strategies.     

Community behavior and amyloid-associated phenotypes among a panel of uropathogenic E. coli

Uropathogenic Escherichia coli (UPEC) are the major causative agents of urinary tract infection and engage in a coordinated genetic and molecular cascade to colonize the urinary tract. Disrupting the assembly and/or function of virulence factors and bacterial biofilms has emerged as an attractive target for the development of new therapeutic strategies to prevent and treat urinary tract infection, particularly in the era of increasing antibiotic resistance among human pathogens. UPEC vary widely in their genetic and molecular phenotypes and more data are needed to understand the features that distinguish isolates as more or less virulent and as more robust biofilm formers or poor biofilm formers. Curli are extracellular functional amyloid fibers produced by E. coli that contribute to pathogenesis and influence the host response during urinary tract infection (UTI). We have examined the production of curli and curli-associated phenotypes including biofilm formation among a specific panel of human clinical UPEC that has been studied extensively in the mouse model of UTI. Motility, curli production, and curli-associated biofilm formation attached to plastic were the most prevalent behaviors, shared by most clinical isolates. We discuss these results in the context on the previously reported behavior and phenotypes of these isolates in the murine cystitis model in vivo.     

Transformation of Brevibacillus,a soil microbe to an uropathogen with hemagglutination trait

An urinary tract infection (UTI) with Brevibacillus agri, an aerobic soil bacteria is discussed. The preliminary urine analysis tested negative for UTI, while the patient was diagnosed with focal pyelonephritis. The urine sample was analyzed for the presence of possible micro-organisms. The isolated micro-organism was phenotypically characterized and compared with a standard B. agri strain and an established uropathogen Eschericia coli, CFT073. Each experimental mouse was trans-urethrally infected using 2.5 × 10⁸ c.f.u. for the generation of an UTI model. The kidney tissues were stored in buffered 10 % formaldehyde solution for histopathological analysis. The destruction of the glomerular and tubular morphology with prominent hemagglutination in the tubular region in the mouse kidneys were confirmed by light microscopic examination of the H&E stained sections. Hence, the identity of pathogen was confirmed using the 16S rRNA gene sequencing. The phylogenetic tree constructed using the 16S rRNA sequence obtained from the isolated microbial strain showed 99 % similarity with the strain, B. agri AB112716. Finally this study concludes based on the phenotypic characteristics, production of lipopolysaccharide, the ability to aggregate in the presence of ammonium sulphate, agglutinate erythrocytes in the presence of mannose, and the potential to resist the interactions of serum, the possibility that the soil microbe could have undergone genotypic modification to cause UTI. However, further detailed and in-depth genetic analysis are required to point out exactly how the soil bacterium has adapted itself to cause infection in a human subject.     

Research Article: NOD2 is dispensable for ATG16L1 deficiency-mediated resistance to urinary tract infection

NOD2 (nucleotide-binding oligomerization domain containing 2) functions as a pathogen sensor and is involved in development of Crohn disease, a form of inflammatory bowel disease. NOD2 functions in concert with the autophagy protein ATG16L1, which is also implicated in Crohn disease. Recently, we identified a novel protective role of ATG16L1 deficiency in uropathogenic Escherichia coli-induced urinary tract infections (UTIs), which are common infectious diseases in humans. Given the known roles of NOD2 in recruiting ATG16L1 to the bacterial entry site, autophagy induction, and Crohn disease, we hypothesized that NOD2 may also play an important role in UTI pathogenesis. Instead, we found evidence that NOD2 is dispensable in the pathogenesis of UTIs in mice and humans. First, loss of Nod2 did not affect the clearance of bacteriuria and the recruitment of innate immune cells to the bladder. Second, we showed that, although nod2 ^−/− mice display increased kidney abscesses in the upper urinary tract, there were no increased bacterial loads or persistence in this niche. Third, although a previous study indicates that loss of Nod2 reverses the protection from intestinal infection afforded by loss of ATG16L1 in mice, we found NOD2 deficiency did not reverse the ATG16L1-deficiency-induced protection from UTI. Finally, a population-based study of a cohort of 1819 patients did not reveal any association of NOD2 polymorphisms with UTI incidence. Together, our data indicated that NOD2 is dispensable for UTI pathogenesis in both mice and humans and does not contribute to ATG16L1-deficiency-induced resistance to UTI in mice.     

Human alpha defensin 5 expression in the human kidney and urinary tract

Background

The mechanisms that maintain sterility in the urinary tract are incompletely understood. Recent studies have implicated the importance of antimicrobial peptides (AMP) in protecting the urinary tract from infection. Here, we characterize the expression and relevance of the AMP human alpha-defensin 5 (HD5) in the human kidney and urinary tract in normal and infected subjects.

Methodology/Principal Findings

Using RNA isolated from human kidney, ureter, and bladder tissue, we performed quantitative real-time PCR to show that DEFA5, the gene encoding HD5, is constitutively expressed throughout the urinary tract. With pyelonephritis, DEFA5 expression significantly increased in the kidney. Using immunoblot analysis, HD5 production also increased with pyelonephritis. Immunostaining localized HD5 to the urothelium of the bladder and ureter. In the kidney, HD5 was primarily produced in the distal nephron and collecting tubules. Using immunoblot and ELISA assays, HD5 was not routinely detected in non-infected human urine samples while mean urinary HD5 production increased with E.coli urinary tract infection.

Conclusions/Significance

DEFA5 is expressed throughout the urinary tract in non-infected subjects. Specifically, HD5 is expressed throughout the urothelium of the lower urinary tract and in the collecting tubules of the kidney. With infection, HD5 expression increases in the kidney and levels become detectable in the urine. To our knowledge, our findings represent the first to quantitate HD5 expression and production in the human kidney. Moreover, this is the first report to detect the presence of HD5 in infected urine samples. Our results suggest that HD5 may have an important role in maintaining urinary tract sterility.     

ATG16L1 and pathogenesis of urinary tract infections

Autophagy is generally considered to be antipathogenic. The autophagy gene ATG16L1 has a commonly occurring mutation associated with Crohn disease (CD) and intestinal cell abnormalities. Mice hypomorphic for ATG16L1 (ATG16L1^HM) recreate specific features of CD. Our recent study shows that the same ATG16L1^HM mice that are susceptible to intestinal inflammatory disease are protected from urinary tract infections (UTI), a common and important human disease primarily caused by uropathogenic E. coli (UPEC). UPEC colonize the bladder and exhibit both luminal and intra-epithelial stages. The host responds by recruiting innate immune cells and shedding infected epithelial cells to clear infection. Despite these countermeasures, UPEC can persist within the bladder epithelium as membrane-enclosed quiescent intracellular reservoirs (QIRs) that can seed recurrent UTI. The mechanisms of persistence remain unknown. In this study, we show that ATG16L1 deficiency protects the host against acute UTI and UPEC latency. ATG16L1^HM mice clear urinary bacterial loads more rapidly and thoroughly due to ATG16L1-deficient innate immune components. Furthermore, ATG16L1^HM mice exhibit superficial urothelial cell-autonomous architectural aberrations that also result in significantly reduced QIR numbers. Our findings reveal a host-protective effect of ATG16L1 deficiency in vivo against a common pathogen.     

Impact of Host Age and Parity on Susceptibility to Severe Urinary Tract Infection in a Murine Model

The epidemiology and bacteriology of urinary tract infection (UTI) varies across the human lifespan, but the reasons for these differences are poorly understood. Using established monomicrobial and polymicrobial murine UTI models caused by uropathogenic Escherichia coli (UPEC) and/or Group B Streptococcus (GBS), we demonstrate age and parity as inter-related factors contributing to UTI susceptibility. Young nulliparous animals exhibited 10–100-fold higher bacterial titers compared to older animals. In contrast, multiparity was associated with more severe acute cystitis in older animals compared to age-matched nulliparous controls, particularly in the context of polymicrobial infection where UPEC titers were ∼1000-fold higher in the multiparous compared to the nulliparous host. Multiparity was also associated with significantly increased risk of chronic high titer UPEC cystitis and ascending pyelonephritis. Further evidence is provided that the increased UPEC load in multiparous animals required TLR4-signaling. Together, these data strongly suggest that the experience of childbearing fundamentally and permanently changes the urinary tract and its response to pathogens in a manner that increases susceptibility to severe UTI. Moreover, this murine model provides a system for dissecting these and other lifespan-associated risk factors contributing to severe UTI in at-risk groups.     

1H NMR-based metabolic profiling of urinary tract infection: combining multiple statistical models and clinical data

Urinary tract infection (UTI) encompasses a variety of clinical syndromes ranging from mild to life-threatening conditions. As such, it represents an interesting model for the development of an analytically based scoring system of disease severity and/or host response. Here we test the feasibility of this concept using ¹H NMR based metabolomics as the analytical platform. Using an exhaustively clinically characterized cohort and taking advantage of the multi-level study design, which opens possibilities for case?Ccontrol and longitudinal modeling, we were able to identify molecular discriminators that characterize UTI patients. Among those discriminators a number (e.g. acetate, trimethylamine and others) showed association with the degree of bacterial contamination of urine, whereas others, such as, for instance, scyllo-inositol and para-aminohippuric acid, are more likely to be the markers of morbidity.     

Urinary Proteins,Vitamin D and Genetic Polymorphisms as Risk Factors for Febrile Urinary Tract Infection and Relation with Bacteremia: A Case Control Study

Objective/Purpose

Febrile urinary tract infection (UTI) is a common bacterial disease that may lead to substantial morbidity and mortality especially among the elderly. Little is known about biomarkers that predict a complicated course. Our aim was to determine the role of certain urinary cytokines or antimicrobial proteins, plasma vitamin D level, and genetic variation in host defense of febrile UTI and its relation with bacteremia.

Methods

A case-control study. Out of a cohort of consecutive adults with febrile UTI (n = 787) included in a multi-center observational cohort study, 46 cases with bacteremic E.coli UTI and 45 cases with non-bacteremic E.coli UTI were randomly selected and compared to 46 controls. Urinary IL-6, IL-8, LL37, β-defensin 2 and uromodulin as well as plasma 25-hydroxyvitamin D were measured. In 440 controls and 707 UTI patients polymorphisms were genotyped in the genes CXCR1, DEFA4, DEFB1, IL6, IL8, MYD88, UMOD, TIRAP, TLR1, TLR2, TLR5 and TNF.

Results

IL-6, IL-8, and LL37 are different between controls and UTI patients, although these proteins do not distinguish between patients with and without bacteremia. While uromodulin did not differ between groups, inability to produce uromodulin is more common in patients with bacteremia. Most participants in the study, including the controls, had insufficient vitamin D and, at least in winter, UTI patients have lower vitamin D than controls. Associations were found between the CC genotype of IL6 SNP rs1800795 and occurrence of bacteremia and between TLR5 SNP rs5744168 and protection from UTI. The rare GG genotype of IL6 SNP rs1800795 was associated with higher β-defensin 2 production.

Conclusion

Although no biomarker was able to distinguish between UTI with or without bacteremia, two risk factors for bacteremia were identified. These were inability to produce uromodulin and an IL6 rs1800795 genotype.     

Fitness of Escherichia coli during Urinary Tract Infection Requires Gluconeogenesis and the TCA Cycle

Microbial pathogenesis studies traditionally encompass dissection of virulence properties such as the bacterium''s ability to elaborate toxins, adhere to and invade host cells, cause tissue damage, or otherwise disrupt normal host immune and cellular functions. In contrast, bacterial metabolism during infection has only been recently appreciated to contribute to persistence as much as their virulence properties. In this study, we used comparative proteomics to investigate the expression of uropathogenic Escherichia coli (UPEC) cytoplasmic proteins during growth in the urinary tract environment and systematic disruption of central metabolic pathways to better understand bacterial metabolism during infection. Using two-dimensional fluorescence difference in gel electrophoresis (2D-DIGE) and tandem mass spectrometry, it was found that UPEC differentially expresses 84 cytoplasmic proteins between growth in LB medium and growth in human urine (P<0.005). Proteins induced during growth in urine included those involved in the import of short peptides and enzymes required for the transport and catabolism of sialic acid, gluconate, and the pentose sugars xylose and arabinose. Proteins required for the biosynthesis of arginine and serine along with the enzyme agmatinase that is used to produce the polyamine putrescine were also up-regulated in urine. To complement these data, we constructed mutants in these genes and created mutants defective in each central metabolic pathway and tested the relative fitness of these UPEC mutants in vivo in an infection model. Import of peptides, gluconeogenesis, and the tricarboxylic acid cycle are required for E. coli fitness during urinary tract infection while glycolysis, both the non-oxidative and oxidative branches of the pentose phosphate pathway, and the Entner-Doudoroff pathway were dispensable in vivo. These findings suggest that peptides and amino acids are the primary carbon source for E. coli during infection of the urinary tract. Because anaplerosis, or using central pathways to replenish metabolic intermediates, is required for UPEC fitness in vivo, we propose that central metabolic pathways of bacteria could be considered critical components of virulence for pathogenic microbes.     

Effects of intravesical liposome-mediated human beta-defensin-2 gene transfection in a mouse urinary tract infection model

The purpose of this study was to assess human β-defensin-2 (hBD-2) gene transfection in human bladder epithelial cells and its therapeutic efficacy in a rat urinary tract infection (UTI) model via liposome mediated gene transfer. A large amount of hBD2 production (36.5 ± 3.2 ng/10(6) cells) was demonstrated in transfected cells' supernatants. In addition, a detectable amount of hBD-2 was identified in rats' urine (4.77 ± 1.4 ng/mL) by ELISA. Expression of the transgene hBD-2 in transfected cells and rats' bladders was also confirmed by RT-PCR and Western blotting. Immunohistochemistry revealed that the transgene hBD-2 expressed in the entire epithelial layer of the transduced bladders. Numbers of bacterial colony-forming units in urine and bladders from hBD2 gene treated UTI rats were significantly lower than those from the UTI rats administered PBS at 24, 36, and 72 hr after infection (P < 0.05). In addition, in vivo expression of hBD-2 reduced mucosal damage, interstitial edema and inflammatory cell infiltration in UTI animals. The results indicate that successful inhibition of UTI progression can be produced by hBD2 gene therapy. The liposome-mediated hBD2 plasmid DNA transfection system appears to be a promising method for antimicrobial gene therapy of UTI.     

Clinical validation of integrated nucleic acid and protein detection on an electrochemical biosensor array for urinary tract infection diagnosis

Background

Urinary tract infection (UTI) is a common infection that poses a substantial healthcare burden, yet its definitive diagnosis can be challenging. There is a need for a rapid, sensitive and reliable analytical method that could allow early detection of UTI and reduce unnecessary antibiotics. Pathogen identification along with quantitative detection of lactoferrin, a measure of pyuria, may provide useful information towards the overall diagnosis of UTI. Here, we report an integrated biosensor platform capable of simultaneous pathogen identification and detection of urinary biomarker that could aid the effectiveness of the treatment and clinical management.

Methodology/Principal Findings

The integrated pathogen 16S rRNA and host lactoferrin detection using the biosensor array was performed on 113 clinical urine samples collected from patients at risk for complicated UTI. For pathogen detection, the biosensor used sandwich hybridization of capture and detector oligonucleotides to the target analyte, bacterial 16S rRNA. For detection of the protein biomarker, the biosensor used an analogous electrochemical sandwich assay based on capture and detector antibodies. For this assay, a set of oligonucleotide probes optimized for hybridization at 37°C to facilitate integration with the immunoassay was developed. This probe set targeted common uropathogens including E. coli, P. mirabilis, P. aeruginosa and Enterococcus spp. as well as less common uropathogens including Serratia, Providencia, Morganella and Staphylococcus spp. The biosensor assay for pathogen detection had a specificity of 97% and a sensitivity of 89%. A significant correlation was found between LTF concentration measured by the biosensor and WBC and leukocyte esterase (p<0.001 for both).

Conclusion/Significance

We successfully demonstrate simultaneous detection of nucleic acid and host immune marker on a single biosensor array in clinical samples. This platform can be used for multiplexed detection of nucleic acid and protein as the next generation of urinary tract infection diagnostics.     

Enterococcus faecalis Subverts and Invades the Host Urothelium in Patients with Chronic Urinary Tract Infection

Bacterial urinary tract infections (UTI) are a major growing concern worldwide. Uropathogenic Escherichia coli has been shown to invade the urothelium during acute UTI in mice and humans, forming intracellular reservoirs that can evade antibiotics and the immune response, allowing recurrence at a later date. Other bacterial species, such as Staphylococcus saprophyticus, Klebsiella pneumonia and Salmonella enterica have also been shown to be invasive in acute UTI. However, the role of intracellular infection in chronic UTI causing more subtle lower urinary tract symptoms (LUTS), a particular problem in the elderly population, is poorly understood. Moreover, the species of bacteria involved remains largely unknown. A previous study of a large cohort of non-acute LUTS patients found that Enterococcus faecalis was frequently found in urine specimens. E. faecalis accounts for a significant proportion of chronic bladder infections worldwide, although the invasive lifestyle of this uropathogen has yet to be reported. Here, we wanted to explore this question in more detail. We harvested urothelial cells shed in response to inflammation and, using advanced imaging techniques, inspected them for signs of bacterial pathology and invasion. We found strong evidence of intracellular E. faecalis harboured within urothelial cells shed from the bladder of LUTS patients. Furthermore, using a culture model system, these patient-isolated strains of E. faecalis were able to invade a transitional carcinoma cell line. In contrast, we found no evidence of cellular invasion by E. coli in the patient cells or the culture model system. Our data show that E. faecalis is highly competent to invade in this context; therefore, these results have implications for both the diagnosis and treatment of chronic LUTS.