Inhibition of sodium urate crystal adherence to bladder surface by polysaccharide

Evaluation of the metabolism of glycosaminoglycans in patients with interstitial cystis

INTRODUCTION

Painful bladder syndrome/interstitial cystitis (PBS/IC) pathogenesis is not fully known, but evidence shows that glycosaminoglycans (GAG) of bladder urothelium can participate in its genesis. The loss of these compounds facilitates the contact of urine compounds with deeper portions of bladder wall triggering an inflammatory process. We investigated GAG in urine and tissue of PBS/IC and pure stress urinary incontinence (SUI) patients to better understand its metabolism.

MATERIALS AND METHODS

Tissue and urine of 11 patients with PBS/IC according to NIDDK criteria were compared to 11 SUI patients. Tissue samples were analyzed by histological, immunohistochemistry and immunofluorescence methods. Statistical analysis were performed using t Student test and Anova, considering significant when p < 0.05.

RESULTS

PBS/IC patients had lower concentration of GAG in urine when compared to SUI (respectively 0.45 ± 0.11 x 0.62 ± 0.13 mg/mg creatinine, p < 0.05). However, there was no reduction of the content of GAG in the urothelium of both groups. Immunofluorescence showed that PBS/IC patients had a stronger staining of TGF-beta, decorin (a proteoglycan of chondroitin/dermatan sulfate), fibronectin and hyaluronic acid.

CONCLUSION

the results suggest that GAG may be related to the ongoing process of inflammation and remodeling of the dysfunctional urothelium that is present in the PBS/IC.

Is there a role for pentosan polysulfate in the prevention of calcium oxalate stones?

The clinical role for pentosan polysulfate (PPS) in the prevention of calcium oxalate urolithiasis is not known. Crystallization and aggregation are important steps in calcium oxalate stone formation, and PPS has been shown to inhibit these steps, both in vitro and in vivo. In addition, PPS has a role in repairing injured urothelium and inhibiting adhesion to epithelial defects. A randomized double-blind placebo-controlled study appears warranted to assess the utility of PPS in the prevention of recurrent calcium oxalate stones.

Urothelial cytoprotective activity of Tamm-Horsfall protein isolated from the urine of healthy subjects and patients with interstitial cystitis

PURPOSE

Tamm-Horsfall protein (THP) is a ubiquitous urinary protein with essentially no known function. We propose that THP is a cytoprotective agent that protects the urothelium from cationic species. To test this hypothesis we isolated THP from normal and interstitial cystitis urine to see if it could protect cultured cells from damage induced by the polyamine, protamine sulfate (PS).

METHODS

Tamm-Horsfall protein was extracted from the urine of interstitial cystitis (IC) patients (N=28) and normal volunteers (N=5). Urothelial target cells (T24) were radiolabeled with 51Cr and then exposed to PS (0-1.0 mg/mL) for either 1.5 or 20 h. The resulting cytotoxicity data (dose-response curves) were then compared with the data obtained when PS was preincubated with 0-0.5 mg/mL of THP (IC vs normal), the semisynthetic polysaccharide, pentosan polysulfate (Elmiron), or human serum albumin.

RESULTS

Toxicity of PS was significantly reduced by incubation with THP (or Elmiron) prior to evaluation by the chromium release assay, but not reduced by incubating with another protein, albumin. Tamm-Horsfall protein from IC patients' urine was less protective than an equal quantity of THP from normal urine.

CONCLUSIONS

These experiments suggest that THP has an important role in bladder mucosal defense mechanisms, protecting the bladder surface from injury. Inability of THP to prevent cytotoxic damage by urinary polyamine or other urinary toxins (cationic species) may be relevant in the etiology of interstitial cystitis, as putative urinary toxic components have been described in the urine of some patients.

Elevated stress protein in transitional cells exposed to urine from interstitial cystitis patients

BACKGROUND

It has been hypothesized that urine from interstitial cystitis (IC) patients may contain one or more toxic factors not present in "normal" urine. Bladder tissues exposed to these toxic factors could have elevated stress proteins. If this assumption is correct, stress protein levels could be a useful marker for identifying patients at risk for developing this syndrome.

METHODS

To experimentally investigate this possibility, a sensitive assay (ELISA) was used to measure levels of the 72 kDa stress protein in urothelial target cells after in vitro exposure to urine from IC patients.

RESULTS

We observed a modest 12% increase in 72 kDa stress protein in cells treated with urine from IC patients compared to cells exposed to normal urine (1.12 compared to 0.99 ng/microg extracted protein; P < 0.05). In addition, it was possible to demonstrate the 72 kDa stress protein in histologic sections obtained from mucosal biopsies of IC patients. Stress protein was located primarily in the surface urothelial cells of the mucosa.

CONCLUSIONS

These results seem to indicate that stress protein could play an important protective role at this particular site. They further suggest that IC urine is more toxic than normal urine and, in contact with underlying urothelial and deeper bladder tissue, may upregulate genes involved in stress protein responses. This may be an important concept in the etiology of IC.

Extracorporeal shock wave lithotripsy and glycosaminoglycans in urine

In 50 calcium oxalate stone-forming patients, the total excretion of glycosaminoglycans (GAGs) and of four of its subgroups [chondroitin-4-sulfate (CS-A), chondroitin-6-sulfate (CS-C), dermatan sulfate (DS), and hyaluronic acid (HY)] were investigated before ESWL and on the following 5 days. The standard value was determined by reference to a group of healthy test subjects. The excretion of GAGs was significantly higher in healthy test persons than in stone-forming patients. Twenty-four hours after ESWL, GAG excretion increased significantly but returned to normal values in the course of three days. ESWL had no influence on the proportional composition of GAG subgroups CS-A, CS-C, DS and HY. The increase in GAG excretion after ESWL indicates a transient injury of renal tissue and of the mucous layer lining the urothelium, respectively. This lesion, however, can be regarded as temporary with restitutio ad integrum later.

Extracorporeal Shock Wave Lithotripsy and Glycosaminoglycans in Urine

In 50 calcium-oxalate stone-forming patients, the total excretion of glycosaminoglycans (GAGs) and four of its subgroups [chondroitin-4-sulfate (CS-A), chondroitin-6-sulfate (CS-C), dermatan sulfate (DS), and hyaluronic acid (HY)] was investigated before ESWL and in the following 5 days. The standard value was determined by reference to a group of healthy test subjects. The excretion of GAGs was significantly higher in healthy test persons than in stone-forming patients. Twenty-four hours after ESWL administration, GAG excretion enhanced significantly but returned to normal values in the course of three days. ESWL had no influence on the proportional composition of GAG subgroups CS-A, CS-C, DS and HY. The increase in GAG excretion after ESWL indicates a transient injury of renal tissue, i.e. of the mucus layer lining the urothelium. This lesion, however, can be regarded as temporary with later restitutio ad integrum.

Intratubular crystallization events

Can urolithiasis start as an intratubular event? Under severe hyperoxaluric conditions in animal models at least crystal formation can. Recently models have been presented that assess the chances of crystal formation under more normal conditions. These models describe changes in fluid composition as this passes through the nephron, these conditions being simulated in in vitro experiments. It appears that under naturally occurring intratubular conditions calcium-salt crystallization takes place within the time tubular fluid normally spends in the nephron. Precipitation starts with a calcium-phosphate phase under conditions found in the thin lambs. This crystalline phase then (partly) dissolves when collecting duct conditions are used, thereby inducing formation of calcium oxalates. Under these conditions the latter increase in size by way of crystal growth and agglomeration. Large particle formation and cell adhesion can eventually result in particle retention and subsequent stone formation. Viewing urolithiasis as originally an intratubular event has consequences for in vitro experiments and treatments, which are discussed in this paper.

Interactions between calcium oxalate monohydrate crystals and Madin-Darby canine kidney cells: endocytosis and cell proliferation

The present investigation was designed to study the biological responses in cultures of Madin-Darby canine kidney (MDCK) cells exposed to calcium oxalate monohydrate (COM) crystals, the most common type of urinary crystals. The addition of COM crystals significantly accelerated the multiplication of MDCK cells and significantly activated the cell viability. After exposure of MDCK cells to COM crystals, scanning electron microscopy revealed that some crystals adhered to the plasma membrane and others were endocytosed by the cell. This cellular uptake of crystals was time dependent from 1 to 8 h and showed a specificity according to crystal type. However, the endocytosis of aggregated COM crystals was less marked than that of non-aggregated crystals. Pre-treatment with each of the glycosaminoglycans (sodium pentosan polysulphate, heparin, and chondroitin sulphate C) produced a significant reduction of the cellular uptake of COM crystals, suggesting that these glycosaminoglycans may play some critical roles in preventing the cellular uptake of crystals. Although investigation in further detail is necessary, we speculate that these crystal-cell interactions, that is, the cellular uptake of crystals and cell proliferation, may be among the earliest processes in the formation of kidney stones.

Glycosaminoglycans in urine and extracorporeal shock wave lithotripsy

In 50 calcium oxalate stone-forming patients, the total excretion of glycosaminoglycans (GAGs) and of four subgroups [chondroitin-4-sulfate (CS-A), chondroitin-6-sulfate (CS-C), dermatan sulfate (DS) and hyaluronic acid (HY)] were investigated before extracorporeal shock wave lithotripsy (ESWL) and during the subsequent 5 days. The standard value was determined by reference to a group of healthy test subjects. The excretion of GAGs was significantly higher in healthy test persons than in stone-forming patients. Twenty-four hours after ESWL administration, GAG excretion was enhanced significantly but returned to normal values over the course of 3 days. ESWL had no influence on the proportional composition of GAG subgroups CS-A, CS-C, DS and HY. The increase in GAG excretion after ESWL indicates a transient injury of renal tissue or of the mucus layer lining the urothelium. This lesion, however, can be regarded as temporary with later restitutio ad integrum.

Glycosaminoglycans and other sulphated polysaccharides in calculogenesis of urinary stones

Naturally occurring glycosaminoglycans (GAGs) and other, semisynthetic, sulphated polysaccharides are thought to play an important role in urolithiasis. Processes involved in urinary stone formation are crystallization and crystal retention. Oxalate transport and renal tubular cell injury are determining factors in these processes. In this article experimental results concerning the possible mechanisms of action of GAGs and other sulphated polysaccharides are reviewed. GAGs are inhibitors of crystal growth and agglomeration and possibly also of nucleation. They can prevent crystal adherence, correct an abnormal oxalate flux and prevent renal tubular cell damage.

Decreased expression of a glycoprotein component of bladder surface mucin (GP1) in interstitial cystitis

Interstitial cystitis is a disease of unknown etiology characterized by unremitting urinary frequency, urgency and suprapubic pain. Recently, a change in urothelial permeability has been identified in interstitial cystitis patients that is presumably mediated by aberrations in bladder surface mucin. For this study we evaluated qualitative changes in a previously defined glycoprotein component of this layer (GP1) as it occurs in interstitial cystitis patients and normal controls. Paraffinized bladder biopsies were obtained from 23 interstitial cystitis patients (all meeting National Institutes of Health inclusion criteria) and 11 normal controls. All biopsy tissue was stained with hematoxylin and eosin, and periodic acid, Schiff reaction. The tissues were examined immunohistochemically for GP1 using an anti-GP1 serum. Periodic acid, Schiff staining clearly identified bladder surface proteoglycans in all specimens. Moderate GP1 reactivity was noted in all normal control specimens. Alternatively, GP1 expression was absent in 35% of the interstitial cystitis patient biopsies and decreased in 61%. These data demonstrate qualitative GP1 changes in a majority of interstitial cystitis patients. It is unknown whether these differences have an impact on the pathogenesis of interstitial cystitis. However, our findings suggest that the absence or decreased expression of GP1 in interstitial cystitis bladder biopsies may serve as a marker to characterize the disease further in conjunction with clinical findings.

Bladder permeability in interstitial cystitis is similar to that of normal volunteers: direct measurement by transvesical absorption of 99mtechnetium-diethylenetriaminepentaacetic acid

Bladder permeability was directly measured with the radionuclide used clinically for detecting vesicoureteral reflux (99mtechnetium-diethylenetriaminepentaacetic acid, 99mTc-DTPA) in 10 interstitial cystitis patients diagnosed according to National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases criterion and compared to 9 sex matched, symptom-free, normal volunteers. After functional bladder capacity was determined (capacity at which the patient demands fluid inflow to stop), the bladder was emptied and 5 mCi. 99mTc-DTPA in 10 ml. of saline were infused followed by normal saline to 80% of functional capacity. This was done to normalize the patients to the same low bladder pressure, since previous studies of rabbits indicated that bladder permeability is low and not significantly different at 20% and 60% of anesthetized bladder capacity (defined as the volume producing an intravesical pressure of 20 cm. water). Radioactivity of 1 ml. serum specimens taken at 0, 2, 15 and 30 minutes after radionuclide infusion was determined in a gamma counter, corrected for radioactive decay and converted to per cent of instilled dose per whole body based on blood volume estimated from body weight for each individual. There was considerable interindividual variability in the absorption between the patients and the volunteers. Analysis of variance of these data showed no statistically significant difference between the patients and controls at any time sampled. These results indicate that while some interstitial cystitis patients have a more permeable bladder than others, the same is true for normal, symptom-free volunteers. Thus, the concept of increased bladder permeability in interstitial cystitis is not supported by this direct measurement of bladder permeability.

Epithelial dysfunction in nonbacterial cystitis (interstitial cystitis)

Traditional concepts of impermeability of the bladder have centered around unique cellular tight junctions and ion pumps. However, recent data from our laboratory have shown that the bladder epithelium in animals and humans relies primarily on its surface glycosaminoglycans to maintain its impermeability. This study demonstrates the first disease associated with an epithelial dysfunction of the bladder, that is a leaky epithelium. The study consisted of 31 normal subjects and 56 individuals with interstitial cystitis. Interstitial cystitis patients were shown to have a leaky epithelium by placing a solution of concentrated urea into the bladder and measuring the absorption. The normal subjects absorbed 4.3% in 45 minutes, while the interstitial cystitis patients absorbed 25% (difference is highly significant, p less than 0.005). Interstitial cystitis patients with Hunner's ulcers (10) had a 34.5% absorption rate, while those without ulcers absorbed 22.8% (46). This difference also was highly significant (p = 0.002) and supports the concept that patients with ulcers have clinically worse disease.

Do extracorporeal shock waves affect urinary excretion of glycosaminoglycans?

Urinary excretion of glycosaminoglycans (GAGs) was studied in 9 anaesthetised dogs and 10 patients with single kidneys. The animals were studied for 4 to 5 hours after administration of shock waves to 1 kidney, the contralateral organ serving as control. Urinary excretion of GAGs was measured on both sides. The patients were studied 0 to 24 and 32 to 56 h after extracorporeal shock wave lithotripsy (ESWL). In the animals an increased mean urinary excretion of GAGs was observed on both sides; this was more marked in the treated kidney. The increase reflects tissue injury in the exposed kidney induced by the extracorporeal shock waves. No increase in mean urinary excretion of GAGs was observed in the patients.

Influence of indomethacin on the adherence of urease-induced crystals to rat bladder epithelium

The mucous coat lining the urinary tract has a barrier function which prevents bacteria and crystals from adhering to the uroepithelium. The mucous coat of the gastric mucosa is sensitive to prostaglandins, and prostaglandin synthetase inhibitors induce gastric erosions and disrupt the continuity of the mucous lining. To determine whether prostaglandin synthetase inhibitors also exert a similar effect on the uroepithelium, rats were given indomethacin intraperitoneally or orally. The effect of this treatment on the adhesion of urease-induced crystals to rat bladder mucosa was studied using a previously developed in-vivo method. Both when given intraperitoneally and orally in a dose of one mg. per kg. b.w. for six weeks, indomethacin significantly increased crystal adherence. This constitutes indirect evidence for the concept that prostaglandins influence the mucous coat of the rat urinary tract and reduce its antiadhesive properties.

Decreased urinary uronic acid levels in individuals with interstitial cystitis

The pathogenesis of interstitial cystitis currently is unknown. A possible etiology is that the transitional epithelium is defective, leading to molecular leaks that initiate the disease complex. An important surface defense mechanism is the glycosaminoglycans or polysaccharides that line the bladder epithelium and act as a nonspecific antiadherence factor blocking access of bacteria, microcrystals, proteins and ions to the underlying transitional cells. We examined the excretion of urinary macromolecular uronic acid and glycosaminoglycans in normal individuals and those with interstitial cystitis. A total of 37 controls had a mean macromolecular uronic acid level of 56 nmol. per mg. creatinine, compared to 40.2 nmol. per mg. creatinine in 43 patients with active disease (differences were significant, p equals 0.03). The median excretions of glycosaminoglycan uronate for controls and patients were 15.1 and 11.1 nmol. per mg. creatinine, respectively. (There was an over-all tendency to decrease excretion in patients with a p value of 0.06.) Specimens obtained at cystoscopy from patients with active interstitial cystitis had ureteral macromolecular uronic acid levels of 40.5 nmol. uronate per mg. creatinine compared to 43.6 nmol. uronate per mg. creatinine from the bladder. Interstitial cystitis patients had 16.0 nmol. glycosaminoglycan uronate per mg. creatinine compared to 14.6 nmol. per mg. creatinine in normal controls. Neither of these differences was statistically significant. It would appear that there is a tendency to lower macromolecular uronic acid and polysaccharide excretion in individuals afflicted with this syndrome.

Bladder surface glycosaminoglycans: an epithelial permeability barrier

Sulfated polysaccharide's ability to modulate the movement of small molecules was examined both in vivo and in vitro. For the in vivo test, the rabbit bladder was utilized and C-14 labeled urea 45-Ca, or 3H2O was placed into the lumen of control bladders, bladders pretreated with protamine sulfate (20 mg./cc) and bladders pretreated with protamine sulfate (20 mg./cc) plus pentosanpoly-sulfate (PPS), 10 mg./cc. After 45 minutes, the controls absorbed 21% of the urea, 16% of the calcium, and 38% of the 3H2O; the protamine treated group 40% urea, 23% calcium, and 51% H2O; the PPS only group 22% urea and the protamine plus PPS group absorbed 24% of urea, 18% calcium, and 44% water. Differences between the control and protamine groups were statistically significant, p less than 0.01 for urea 45-Ca and 3H2O. The bladder mucosa contained a significantly higher concentration of urea and calcium after protamine treatment which were both reversed by PPS (p less than 0.01) while 3H2O content went down significantly (p = 0.03), reflecting a loss of the hydrophilic effect of bladder GAG. The control mucosas had 250 cpm/mg. tissue urea for Ca 64 cpm/mg. and water 262 cpm/mg., the protamine group urea 498 cpm/mg., Ca 190 cpm/mg., and H2O 139 cpm/mg.; the protamine plus PPS group urea 344 cpm/mg., Ca 129 cpm/mg., and water 168 cpm/mg. For the in vitro studies, an Ussing chamber was employed. Normal rabbit bladder membranes were placed in the chambers and the potential difference was zeroed across the membrane. There were three groups, membranes that were treated only with the irrigating solution, membranes pretreated with protamine, and membranes pretreated with protamine plus PPS. At the end of 40 minutes, there was an approximately 1.2% movement of urea across the control membrane, a 3.5% movement across the protamine treated membrane (a significant increase p less than 0.001) and a 1.1% movement across the protamine plus PPS treated membrane. It would appear that the surface polysaccharide may play an important role as a bladder permeability barrier in modulating both charged and uncharged small molecule movement in that its ability to impair such movement can be inhibited by protamine and this protamine effect can be reversed by a treatment with an exogenous sulfated polysaccharide.

Effect of extract of Hirudo Medicinalis L. against adherence of calcium oxalate crystals to acid-injured bladder mucosa

The effect of extract of Hirudo Medicinalis L. on preventing the adhesion of calcium oxalate crystals to 0.1 M hydrochloric acid-injured bladder urothelium of the rat was studied. It was found that in this species the extract coated to the bladder mucosa after it was instilled into the chemically injured bladder; and the adhesion of calcium oxalate crystals was prevented. In regard to the anti-adhesion property the Hirudo extract appears more effective than heparin, a documented glycosaminoglycan.

Adherence of urease-induced crystals to rat bladder epithelium following acute infection with different uropathogenic microorganisms

Apart from urine supersaturation with respect to struvite and calcium phosphate, crystal retention is considered to be necessary for the formation of infection stones. This study was performed to investigate the role of the mucous coat in rat bladders in the adhesion of sterile urease-induced crystals and to determine to what extent the adhesion was influenced by infection. Elimination of the mucous coat with 0.1 M HCl increased the adherence of crystals six times compared to that in bladders with an intact mucous coat. Infection with Proteus mirabilis, Escherichia coli, enterococci and Ureaplasma urealyticum increased the adherence six, five, four and two times, respectively. Injury to the mucous coat may thus be one mechanism by which microorganisms can contribute to the formation of infection stones in the urinary tract.

Reversible inactivation of bladder surface glycosaminoglycan antibacterial activity by protamine sulfate

Prior studies in our laboratory have shown that the bladder surface is lined with glycosaminoglycans which appear to be an important antibacterial defense mechanism that operates by resisting bacterial adherence and infection. The present study further implicates bladder surface glycosaminoglycans as the key antiadherent factor and also suggests a potential model for diseases (such as urinary tract infections) whereby the antiadherent surface of the bladder is inactivated biochemically. Protamine sulfate treatment of bladder tissue was found to significantly increase bacterial adherence to the urinary bladder by approximately 2.3-fold. This effect was reversed by a second treatment of the bladder with pentosanpolysulfate (a polysaccharide known to duplicate the surface antiadherent effect). Protamine sulfate had no effect on bacterial viability or bacterial adherence when bacteria were pretreated with it.