Urine concentrations of human beta-defensins and ribonuclease 7 in urinary tract infection and asymptomatic bacteriuria.

Antimicrobial peptides (AMPs) provide a first line of defense against bacterial infections. Here we report that urine levels of AMPs, locally produced in the urinary tract, are lower in individuals with asymptomatic bacteriuria (ABU) compared to patients with urinary tract infection (UTI).

Cutaneous Burn Injury Modulates Urinary Antimicrobial Peptide Responses and the Urinary Microbiome.

OBJECTIVES: Characterization of urinary bacterial microbiome and antimicrobial peptides after burn injury to identify potential mechanisms leading to urinary tract infections and associated morbidities in burn patients. DESIGN: Retrospective cohort study using human urine from control and burn subjects. SETTING: University research laboratory. PATIENTS: Burn patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Urine samples from catheterized burn patients were collected hourly for up to 40 hours. Control urine was collected from "healthy" volunteers. The urinary bacterial microbiome and antimicrobial peptide levels and activity were compared with patient outcomes. We observed a significant increase in urinary microbial diversity in burn patients versus controls, which positively correlated with a larger percent burn and with the development of urinary tract infection and sepsis postadmission, regardless of age or gender. Urinary psoriasin and ß-defensin antimicrobial peptide levels were significantly reduced in burn patients at 1 and 40 hours postadmission. We observed a shift in antimicrobial peptide hydrophobicity and activity between control and burn patients when urinary fractions were tested against Escherichia coli and Enterococcus faecalis urinary tract infection isolates. Furthermore, the antimicrobial peptide activity in burn patients was more effective against E. coli than E. faecalis. Urinary tract infection-positive burn patients with altered urinary antimicrobial peptide activity developed either an E. faecalis or Pseudomonas aeruginosa urinary tract infection, suggesting a role for urinary antimicrobial peptides in susceptibility to select uropathogens. CONCLUSIONS: Our data reveal potential links for urinary tract infection development and several morbidities in burn patients through alterations in the urinary microbiome and antimicrobial peptides. Overall, this study supports the concept that early assessment of urinary antimicrobial peptide responses and the bacterial microbiome may be used to predict susceptibility to urinary tract infections and sepsis in burn patients.

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, ß-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 ß-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.

Interplay between bladder microbiota and urinary antimicrobial peptides: mechanisms for human urinary tract infection risk and symptom severity.

Resident bacterial communities (microbiota) and host antimicrobial peptides (AMPs) are both essential components of normal host innate immune responses that limit infection and pathogen induced inflammation. However, their interdependence has not been investigated in the context of urinary tract infection (UTI) susceptibility. Here, we explored the interrelationship between the urinary microbiota and host AMP responses as mechanisms for UTI risk. Using prospectively collected day of surgery (DOS) urine specimens from female pelvic floor surgery participants, we report that the relative abundance and/or frequency of specific urinary microbiota distinguished between participants who did or did not develop a post-operative UTI. Furthermore, UTI risk significantly correlated with both specific urinary microbiota and ß-defensin AMP levels. Finally, urinary AMP hydrophobicity and protease activity were greater in participants who developed UTI, and correlated positively with both UTI risk and pelvic floor symptoms. These data demonstrate an interdependency between the urinary microbiota, AMP responses and symptoms, and identify a potential mechanism for UTI risk. Assessment of bacterial microbiota and host innate immune AMP responses in parallel may identify increased risk of UTI in certain populations.

Role of urinary cathelicidin LL-37 and human ß-defensin 1 in uncomplicated Escherichia coli urinary tract infections.

Cathelicidin (LL-37) and human ß-defensin 1 (hBD-1) are important components of the innate defense in the urinary tract. The aim of this study was to characterize whether these peptides are important for developing uncomplicated Escherichia coli urinary tract infections (UTIs). This was investigated by comparing urinary peptide levels of UTI patients during and after infection to those of controls, as well as characterizing the fecal flora of participants with respect to susceptibility to LL-37 and in vivo virulence. Forty-seven UTI patients and 50 controls who had never had a UTI were included. Participants were otherwise healthy, premenopausal, adult women. LL-37 MIC levels were compared for fecal E. coli clones from patients and controls and were also compared based on phylotypes (A, B1, B2, and D). In vivo virulence was investigated in the murine UTI model by use of selected fecal isolates from patients and controls. On average, UTI patients had significantly more LL-37 in urine during infection than postinfection, and patient LL-37 levels postinfection were significantly lower than those of controls. hBD-1 showed similar urine levels for UTI patients and controls. Fecal E. coli isolates from controls had higher LL-37 susceptibility than fecal and UTI E. coli isolates from UTI patients. In vivo studies showed a high level of virulence of fecal E. coli isolates from both patients and controls and showed no difference in virulence correlated with the LL-37 MIC level. The results indicate that the concentration of LL-37 in the urinary tract and low susceptibility to LL-37 may increase the likelihood of UTI in a complex interplay between host and pathogen attributes.

Detection of renal and urinary tract proteins before and after spaceflight.

BACKGROUND: The recent evolution of genomics and subsequently proteomics offers a major advance in the ability to understand individual human variation in disease and the molecular level changes induced by certain environmental exposures. This original study examines urinary proteome composition to enable the understanding of molecular homeostatic mechanisms in spaceflight and presents the potential for early detection of subclinical disease, microgravity risk mitigation strategies, and countermeasure development for exploration-class missions. METHODS: The urinary proteome composition of six Russian cosmonauts (men, ages 35-51) who flew long-duration missions of 169-199 d was determined 30 d before flight and compared to repeat studies 1 and 7 d postflight. RESULTS: There were 430 proteins identified. Of those, 15 proteins originated in the renal tissues. Of the 15 urinary proteins, 10 were consistently present in the urine. However, the presence of five of the urinary proteins--neutral endopeptidase (NEP), afamin (AFAM), aquaporin-2 (AQP2), aminopeptidase A (AMPE), and dipeptidyl peptidase 4 (DPP4)--was dependent on spaceflight exposure. DISCUSSION: Proteomic investigation of pre- and postflight urine and bioinformation approaches to proteome analysis provide important data relative the mechanism of kidney function in spaceflight. In this initial study, we determined that the evaluation of urinary proteins may help investigators understand changes that are occurring in microgravity. Once additional ground-based and in-flight data are collected, it is feasible to develop targeted studies for tracking specific spaceflight related changes, determine countermeasure and risk-mitigation effectiveness, and possibly detect subclinical disease in flight crewmembers.

Decreased urinary beta-defensin-1 expression as a biomarker of response to arsenic.

Ingestion of arsenic (As) through contaminated drinking water results in increased risks of skin, lung, kidney, and bladder cancers. Due to its association with kidney and bladder cancers, we hypothesized that analysis of the urinary proteome could provide insight into the mechanisms of As toxicity. Urine from participants in a cross-sectional As biomarker study conducted in Nevada, classified as having either high (>or= 100 microg total urinary As/l) or low exposure (< 100 microg total urinary As/l) was analyzed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Two polypeptides, 2.21 and 4.37 kDa, were significantly decreased in the high exposure group (p < 0.05) and were limited to men when stratified by sex. To replicate these findings, urine from participants in a second As study in Chile was analyzed and results confirmed the decrease of the 4.37 kDa polypeptide as well as a 4.76 kDa polypeptide among highly exposed men. These peaks were identified and confirmed as human beta-defensin-1 (HBD-1) peptides. In a separate in vitro experiment, gene expression analysis of As-treated cell lines demonstrated reduced HBD1 mRNA confirming that the observed decrease in HBD-1 resulted from As exposure. HBD-1 is an antimicrobial peptide constitutively expressed in multiple tissues including epithelial cells of the respiratory and urogenital systems. Recent studies support its role as a tumor suppressor gene for urological cancers suggesting that decreased HBD-1 levels may play a role in the development of cancers associated with As exposure. Further studies are warranted to investigate the role of HBD-1 in As-related toxicity.

Characterization of urinary peptide biomarkers of acute rejection in renal allografts.

We previously demonstrated that 4.7 kDa and 4.4 kDa peptides are useful in diagnosing acute rejection in renal transplant recipients. The aim of this study was to characterize these polypeptides and assess their potential as biomarkers. The polypeptides were identified as human beta-Defensin-1 (4.7 kDa) and alpha-1-antichymotrypsin (4.4 kDa), by tandem mass spectrometry and ProteinChip immunoassay. The urinary abundance of both polypeptides, assessed using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS), revealed a reduction in beta-Defensin-1 while alpha-1-antichymotrypsin increased in patients with rejection (p < 0.05) compared with clinically stable transplants. The area under the curve (AUC) for the receiver operator characteristic (ROC) curve for the diagnosis of rejection for the ratio of both peptides combined was 0.912. Longitudinal analysis confirmed a reduction in beta-Defensin-1 with a reciprocal increase in alpha-1-antichymotrypsin as rejection developed. The difference in urinary beta-Defensin-1 levels quantified by radioimmunoassay was 176.8 +/- 122.3 pg/mL in stable patients compared with 83.2 +/- 52.2 pg/mL in patients with acute rejection, with an ROC AUC of 0.749 (p < 0.01). Immunohistochemistry (IHC) confirmed reduced beta-Defensin-1 expression in the renal parenchyma of patients experiencing acute rejection. In conclusion, the ratio of beta-Defensin-1 and alpha-1-antichymotrypsin excretion in the urine is a novel, potentially useful candidate biomarkers of acute rejection.