Urinary excretion of Tamm-Horsfall protein in women with recurrent urinary tract infections

Recent advances in recurrent urinary tract infection from pathogenesis and biomarkers to prevention

Recurrent urinary tract infection (UTI) might be one of the most common problems in urological clinics. Recent research has revealed novel evidence about recurrent UTI and it should be considered a different disease from the first infection. The pathogenesis of recurrent UTI might include two mechanisms, bacterial factors and deficiencies in host defense. Bacterial survival in the urinary bladder after antibiotic treatment and progression to form intracellular bacterial communities might be the most important bacterial factors. In host defense deficiency, a defect in pathogen recognition and urothelial barrier function impairment play the most important roles. Immunodeficiency and urogenital tract anatomical abnormalities have been considered the essential risk factors for recurrent UTI. In healthy women, voiding dysfunction and behavioral factors also increase the risk of recurrent UTI. Sexual intercourse and estrogen deficiency in postmenopausal women might have the strongest association with recurrent UTI. Traditional lifestyle factors such as fluid intake and diet are not considered independent risk factors now. Serum and urine biomarkers to predict recurrent UTI from the first infection have also attracted a wide attention recently. Current clinical evidence suggests that serum macrophage colony-stimulating factor and urinary nerve growth factor have potential predictive value for recurrent UTI. Clinical trials have proven the efficacy of the oral immunoactive agent OM-89 for the prevention of UTI. Vaccines for recurrent UTI are recommended by the latest guidelines and are available on the market.

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.

α-Intercalated cells defend the urinary system from bacterial infection

α-Intercalated cells (A-ICs) within the collecting duct of the kidney are critical for acid-base homeostasis. Here, we have shown that A-ICs also serve as both sentinels and effectors in the defense against urinary infections. In a murine urinary tract infection model, A-ICs bound uropathogenic E. coli and responded by acidifying the urine and secreting the bacteriostatic protein lipocalin 2 (LCN2; also known as NGAL). A-IC-dependent LCN2 secretion required TLR4, as mice expressing an LPS-insensitive form of TLR4 expressed reduced levels of LCN2. The presence of LCN2 in urine was both necessary and sufficient to control the urinary tract infection through iron sequestration, even in the harsh condition of urine acidification. In mice lacking A-ICs, both urinary LCN2 and urinary acidification were reduced, and consequently bacterial clearance was limited. Together these results indicate that A-ICs, which are known to regulate acid-base metabolism, are also critical for urinary defense against pathogenic bacteria. They respond to both cystitis and pyelonephritis by delivering bacteriostatic chemical agents to the lower urinary system.

NGAL-Siderocalin in kidney disease

Kidney damage induces the expression of a myriad of proteins in the serum and in the urine. The function of these proteins in the sequence of damage and repair is now being studied in genetic models and by novel imaging techniques. One of the most intensely expressed proteins is lipocalin2, also called NGAL or Siderocalin. While this protein has been best studied by clinical scientists, only a few labs study its underlying metabolism and function in tissue damage. Structure-function studies, imaging studies and clinical studies have revealed that NGAL-Siderocalin is an endogenous antimicrobial with iron scavenging activity. This review discusses the "iron problem" of kidney damage, the tight linkage between kidney damage and NGAL-Siderocalin expression and the potential roles that NGAL-Siderocalin may serve in the defense of the urogenital system. This article is part of a Special Issue entitled: Cell Biology of Metals.

[Recurrent urinary tract infections]

Recurrent urinary tract infections (RUTI) are a frequent clinical problem in sexually active young women, pregnant or postmenopausal women and in patients with underlying urological abnormalities. The present chapter reviews RUTI based on their classification: relapses, which usually occur early (< 1 month), are caused by the same microorganism and are associated with underlying urological abnormalities, and reinfections, which usually occur later and are caused by a new distinct microorganism (or by the same microorganism usually located in the rectum or uroepithelial cells). The pathogenesis of RUTI is reviewed and the risk factors associated with RUTI in premenopausal women (usually related to sexual activity), postmenopausal women (in whom estrogen deficiency has a significant effect on the vaginal Lactobacillus flora), and in pregnant women are discussed. Likewise, an extensive review of the distinct therapeutic strategies to prevent RUTI is provided: self-treatment of cystitis, continuous antibiotic prophylaxis, postcoital antibiotic prophylaxis, topical vaginal estrogens, Lactobacillus, cranberry juice, intravesical administration of non-virulent E. coli strains and vaccines, among others. Several diagnostic-therapeutic algorithms are included. These algorithms are based on the type of urinary infection (relapse-reinfection), on the type of patient (young, postmenopausal, or pregnant women) and on the number of episodes of RUTI.

[Recurrent urinary tract infections in women. Virulence of pathogens and host reaction]

The interactions of host-specific and microbial factors are responsible for recurrent urinary tract infections (rUTI). The anatomical properties of the female urogenital tract favor colonization by uropathogens. Local factors such as glucose concentration of the urine, stability of the lactobacilli population, the influence of estrogens, the activity of Tamm-Horsfall protein or of defensins, and disturbance of the systemic defense mechanisms dictate the course of an infection. The most prominent uropathogen is E. coli. It expresses various virulence factors including adhesions, toxins, iron uptake systems, and a capsule. It is still unclear if there are virulence factors characteristic for E. coli strains causing rUTI. The formation of intracellular reservoirs by invasion of uroepithelial cells by E. coli could be another, as yet little noticed cause for rUTI. Therefore, in cases of rUTI the application of intracellularly active antibiotics should be considered.

Pathogenesis of urinary tract infections with normal female anatomy

Recurrent urinary tract infections (UTIs) are common among girls and young women who are healthy and have anatomically normal urinary tracts. These infections are a main source of morbidity and health-care costs in this population. The interaction between specific infecting bacteria and urinary tract epithelium characteristics underlies the pathogenesis of this disease. Several pathogen-related factors predispose people to recurrent UTI, including periurethral bacterial colonisation and Escherichia coli virulence. Host behavioural risk factors include voiding dysfunction, high intercourse frequency, and oral contraceptive and spermicide use. The role of vesicoureteral reflux in recurrent childhood UTI is probably overestimated in the medical literature and is important only in a small group of children with high-grade reflux. Family pedigree analysis suggests a familial genetic predisposition for UTI among young females. Animal models show the multigenic nature of recurrent UTI. Putative candidate genes for the disease include ABH blood groups, interleukin-8 receptor (CXCR1), the human leucocyte antigen locus, toll-like receptors, tumour necrosis factor, and Tamm-Horsfall protein.

Interaction of bladder glycoprotein GP51 with uropathogenic bacteria

PURPOSE

A major component of bladder surface mucin is a glycoprotein GP51 (molecular weight 51 kD.). GP51, which has previously been isolated from rabbit mucosa, appears to function as part of the defense mechanism in an in vivo infection model. GP51 coats the epithelium and is secreted into the urine, as detected by immunohistochemical testing and enzyme-linked immunosorbent assay (ELISA). Increased urinary GP51 occurs during urinary tract infection. To elucidate the role of GP51 as a component of the primary defense mechanism we studied interactions with uropathogenic bacterial isolates and urine from symptomatic patients with urinary tract infection.

MATERIALS AND METHODS

ELISA was performed to demonstrate the binding of GP51 and various uropathogens. Immunochemical studies were done using monoclonal antibodies to GP51 to determine the interaction of GP51 with certain uropathogenic isolates, including Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus, S. epidermidis and Streptococcus faecalis. Infected urinary sediments and uropathogenic bacterial cultures were examined by immunocytochemical testing to localize GP51. Antigen inhibition ELISA was done to quantitate urinary GP51 in the urine of 17 normal controls and 19 patients with urinary tract infection.

RESULTS

ELISA revealed that GP51 binds to a wide spectrum of gram-positive and gram-negative uropathogens in semiquantitative fashion. Immunochemical methods confirmed that purified GP51 binds to bacteria, encapsulating and aggregating the bacteria. Clinical specimens showed GP51 localized to bacteria and uroepithelial cells. We observed a significant increase in urinary GP51 in urinary tract infection compared to uninfected urine (p = 0.0003).

CONCLUSIONS

These studies suggest that GP51, a component of bladder mucin, may be a strategic factor in the primary defense mechanism of the bladder.

Evaluation of urinary Tamm-Horsfall protein in post-menopausal diabetic women

Tamm-Horsfall protein (THP), a glycoprotein produced in the thick ascending limb (TAL) and the early distal convoluted tubule (DCT), is normally excreted in large amounts in urine. Urinary THP may be a useful marker for renal damage. The goal of this research project was to determine the THP excretion in control and diabetic post-menopausal women. Twenty-four hour urine samples were collected from 19 controls and 19 diabetic patients (11 non-insulin dependent diabetic mellitus (non-IDDM) patients, and 8 insulin dependent diabetic mellitus (IDDM) patients). Polyacrylamide gel electrophoresis (PAGE), Western blotting, and enzyme linked immunosorbent assay (ELISA) methods were used. It was determined that urinary THP concentrations were significantly decreased in patients with IDDM compared to patients with non-IDDM and controls. In conclusion, laboratory quantitation of urinary THP may be a useful indicator of cellular abnormalities such as reduced protein (THP) synthesis of the cells of the TAL and early DCT in some IDDM patients.

Coating in vitro of erythrocytes with Tamm Horsfall-protein

A method is described to coat isolated peripheral blood erythrocytes in vitro with Tamm-Horsfall Protein (THP, uromodulin). Coating of erythrocytes with THP was accomplished by incubation of the cells in the presence of THP, made monomeric by incubation in a high urea concentration. THP-coating of erythrocytes was dependent on the THP-concentration, maximal coating being obtained at a protein concentration > or = 250 mg/ml. The best coating results were obtained if, during the co-incubation of erythrocytes with THP, urea was removed while the sodium chloride concentration was increased up to a physiologic concentration by means of dialysis. This alteration in chemical conditions promotes THP-polymerisation. Erythrocytes coated in this way could be preserved for at least 5 weeks in preserving solution, making them an interesting source of testing and control material. Coating of erythrocytes with THP could also be accomplished under conditions in which THP was preserved in a monomeric form, which suggests that peripheral blood erythrocytes having binding-sites for THP.

Decreased Tamm-Horsfall protein in lithiasic patients

OBJECTIVES

Tamm-Horsfall glycoprotein (THP) is the most abundant substance of renal origin appearing in urine. It seems to be one of the major inhibitors of calcium oxalate crystal nucleation and/or aggregation, but its role in the pathogenesis of stone formation has not yet been clarified. The present work was undertaken to quantify THP excretion in lithiasic (L) patients, so as to determine if these levels are different from those of control subjects (C).

DESIGN AND METHODS

THP was isolated from human urine by reprecipitation steps, rabbit antiTHP antibody was obtained and its specificity determined, an ELISA was developed and technical conditions standardized, and quantitative measurements of urinary THP were performed on samples from L patients, who had suffered more than one lithiasic episode, and from C subjects. Microtiter plates coated with THP or diluted urine samples were subjected to successive incubation with antiTHP and alkaline phosphatase antirabbit IgG.

RESULTS

A good correlation between measured absorbance and THP concentration in standard and urine samples was observed. Data, expressed as Median and Interquartile Range, are 388/209-626 micrograms THP/mmol creatinine for C (n = 85) and 124/82-171 micrograms THP/mmol creatinine for L (n = 23).

CONCLUSIONS

We have obtained an antiserum antiTHP that can be used in the ELISA technique to determine reliable urinary THP values. The results show a significant decrease of THP excretion in recurrent stone formers compared to controls (p < 0.001) and may have interesting implications in the pathogenesis of urolithiasis.

Calcium oxalate stone agglomeration reflects stone-forming activity: citrate inhibition depends on macromolecules larger than 30 kilodalton

To evaluate the clinical utility of in vitro calcium oxalate monohydrate (COM) crystallization kinetics measurements and to determine the effect of quantitative removal of urinary Tamm-Horsfall glycoprotein on such measurements, we examined 24-hour, room temperature urine collections of patients from our Stone Clinic and of normal subjects from our research laboratories at Ochsner Medical Institutions in New Orleans, LA, and compared their COM kinetic parameters in vitro before and after urine ultrafiltration (30 kd). Data from 53 calcium oxalate stone-forming patients (26% women; mean age, 47 years) who demonstrated radiographic or other evidence of forming at least one stone were compared with data from 22 healthy volunteers (25% women; mean age, 40 years). Hypercalciuria (> 7.5 mm/24 hr), hyperoxaluria (> 0.5 mm/24 hr), and hypocitraturia (< 2.0 mm/24 hr) were present in 38%, 26%, and 26% of the patient population, respectively. Urinary creatinine, urate, calcium, citrate, phosphate, oxalate, pH, volume, total immunoreactive-disaggregated Tamm-Horsfall glycoprotein, and the urine's effects on COM solubility, percent crystal growth inhibition, and crystal agglomeration inhibition [tm] were determined. Calcium oxalate monohydrate agglomeration inhibition, [tm], was reduced in stone-forming patients. It decreased with increasing stone frequency, making [tm] a useful tool for measuring the risk of stone recurrence. Urinary Tamm-Horsfall glycoprotein and citrate concentrations were linearly related to COM agglomeration inhibition. Their effects were synergistic. Tamm-Horsfall glycoprotein removal from urine reduced COM agglomeration inhibition dramatically. Alkali therapy increased urinary citrate concentration and increased [tm].(ABSTRACT TRUNCATED AT 250 WORDS)

Urinary Tamm-Horsfall glycoprotein concentrations in normal and urolithiasis-affected male cats determined by an ELISA

A precise and reproducible enzyme-linked immunosorbent assay (ELISA) which measures urinary cat Tamm-Horsfall glycoprotein (cTHP) was developed in order to investigate the possible role of cTHP in the pathogenesis of feline urolithiasis. Reproducible quantification required that the cTHP be disaggregated with 2M urea and 0.05% Tween 20. It was necessary to standardize rigidly the handling of the samples prior to analysis, since the apparent cTHP concentration varied depending on the preanalysis protocols. Using the sample handling protocol of freezing urine at -70 degrees C before dialysis, urinary cTHP was quantified in male cats with no history of urolithiasis ("normal" cats) and in male cats with a history of urolith formation ("urolithiasis" cats). The mean cTHP concentration in adult, male "normal" cats of 49.2 +/- 35.5 micrograms/ml (N = 23) was significantly lower than the mean cTHP concentration of 95.4 +/- 34.1 micrograms/ml (N = 9) in "urolithiasis" cats (p < 0.01, Students' T-test). These findings indicate a correlation between urolithiasis and high urine cTHP concentrations in male cats which warrants further investigation.