Mechanisms of uropathogenic Escherichia coli persistence and eradication from the urinary tract

Recurrent urinary tract infections (rUTIs) are a source of considerable morbidity in women. The infecting bacteria in both rUTIs and a de novo acute infection have been thought to originate from an extraurinary location. Here, we show in a murine model of UTI that uropathogenic Escherichia coli (UPEC) established quiescent intracellular reservoirs (QIRs) in Lamp1+ endosomes within the urinary bladder epithelium. Depending on the integrity of the urothelial barriers at the time of initial infection, these QIRs were established within terminally differentiated superficial facet cells and/or underlying transitional epithelial cells. Treatment of infected bladders harboring exclusively superficial facet cell QIRs with the cationic protein, protamine sulfate, led to epithelial exfoliation and eradication of bacteria in 100% of treated animals. However, when the bacterial QIRs were harbored in underlying transitional cells, stimulation of epithelial turnover triggered reemergence of viable organisms and recurrence of infection. Thus, our results suggest (i) that bacterial QIRs within the bladder may be a previously unappreciated source of recurrent UTIs and (ii) that inducing epithelial exfoliation may be a therapeutic avenue for treating this heretofore recalcitrant disease.

Interstitial cells: regulators of smooth muscle function

Smooth muscles are complex tissues containing a variety of cells in addition to muscle cells. Interstitial cells of mesenchymal origin interact with and form electrical connectivity with smooth muscle cells in many organs, and these cells provide important regulatory functions. For example, in the gastrointestinal tract, interstitial cells of Cajal (ICC) and PDGFRα(+) cells have been described, in detail, and represent distinct classes of cells with unique ultrastructure, molecular phenotypes, and functions. Smooth muscle cells are electrically coupled to ICC and PDGFRα(+) cells, forming an integrated unit called the SIP syncytium. SIP cells express a variety of receptors and ion channels, and conductance changes in any type of SIP cell affect the excitability and responses of the syncytium. SIP cells are known to provide pacemaker activity, propagation pathways for slow waves, transduction of inputs from motor neurons, and mechanosensitivity. Loss of interstitial cells has been associated with motor disorders of the gut. Interstitial cells are also found in a variety of other smooth muscles; however, in most cases, the physiological and pathophysiological roles for these cells have not been clearly defined. This review describes structural, functional, and molecular features of interstitial cells and discusses their contributions in determining the behaviors of smooth muscle tissues.

Secretory immunoglobulin A and G antibodies prevent adhesion of Escherichia coli to human urinary tract epithelial cells

The adhesion of Escherichia coli to human urinary tract epithelial cells was inhibited by commercial gamma globulin, the total immunoglobulin fraction of human breast milk and urine, as well as the isolated immunoglobulin G and secretory immunoglobulin A fractions of urine from patients with acute pyelonephritis. Urinary anti-O6 antibodies reduced the adhesion of several O6 strains. Absorption of antibodies to the lipopolysaccharide of the adhering strain markedly decreased the antiadhesive capacity of all the immunoglobulin preparations, whereas elimination of antibodies to the capsular polysaccharide antigen consistently had a small but not significant effect. When urine was absorbed with whole, live bacteria of the patients' infecting strains, the antiadhesive effect completely disappeared. Absorption with bacteria lacking pili only partially reduced this effect.

Spontaneous activity of lower urinary tract smooth muscles: correlation between ion channels and tissue function

Smooth muscles from the urethra and bladder display characteristic patterns of spontaneous contractile activity in the filling phase of the micturition cycle. Tonic contractions are seen in the urethral smooth muscles, and phasic contractions occur in the detrusor. Overactivity in the detrusor is a common clinical problem. The ion channels in the smooth muscle membranes play an important role in determining the functional properties, and are obvious targets for treatment of the overactive bladder. Recent evidence suggests that interstitial cells may also play a role in determining the pattern of spontaneous activity, although their precise role is less well established in the urinary tract than in the gut. The ion channels involved in these cells are also of interest. This review discusses what is known of ion channels in these tissues, and their implications for function.

Cytokeratin polypeptide patterns of different epithelia of the human male urogenital tract: immunofluorescence and gel electrophoretic studies

Intermediate filament proteins of normal epithelia of the human and the bovine male urogenital tract and of certain human renal and bladder carcinomas have been studied by immunofluorescence microscopy and by two-dimensional gel electrophoresis of cytoskeletal fractions from microdissected tissue samples. The patterns of expression of cytokeratin polypeptides differ in the various epithelia. Filaments of a cytokeratin nature have been identified in all true epithelial cells of the male urogenital tract, including renal tubules and rete testis. Simple epithelia of renal tubules and collecting ducts of kidney, as well as rete testis, express only cytokeratin polypeptides nos. 7, 8, 18, and 19. In contrast, the transitional epithelia of renal pelvis, ureter, bladder, and proximal urethra contain, in addition to those polypeptides, cytokeratin no. 13 and small amounts of nos. 4 and 5. Most epithelia lining the human male reproductive tract, including those in the epididymis, ductus deferens, prostate gland, and seminal vesicle, synthesize cytokeratin no. 5 in addition to cytokeratins nos. 7, 8, 18, and 19 (cytokeratin no. 7 had not been detected in the prostate gland). Cytokeratin no. 17 has also been identified, but in very low amounts, in seminal vesicle and epididymis. The cytokeratin patterns of the urethra correspond to the gradual transition of the pseudostratified epithelium of the pars spongiosa (cytokeratins nos. 4, 5, 6, 13, 14, 15, and 19) to the stratified squamous epithelium of the fossa navicularis (cytokeratins nos. 5, 6, 10/11, 13, 15, and 19, and minor amounts of nos. 1 and 14). The noncornified stratified squamous epithelium of the glans penis synthesizes cytokeratin nos. 1, 5, 6, 10/11, 13, 14, 15, and 19. In immunofluorescence microscopy, selective cytokeratin antibodies reveal differential staining of different groups or layers of cells in several epithelia that may relate to the specific expression of cytokeratin polypeptides. Human renal cell carcinomas show a simple cytokeratin pattern consisting of cytokeratins nos. 8, 18, and 19, whereas transitional cell carcinomas of the bladder reveal additional cytokeratins such as nos. 5, 7, 13, and 17 in various proportions. The results shows that the wide spectrum of histological differentiation of the diverse epithelia present in the male urogenital tract is accompanied by pronounced changes in the expression of cytokeratin polypeptides and suggest that tumors from different regions of the urogenital tract may be distinguished by their cytokeratin complements.

Diversity of the Escherichia coli type 1 fimbrial lectin. Differential binding to mannosides and uroepithelial cells

Type 1 fimbriae are the most common adhesive organelles of Escherichia coli. Because of their virtual ubiquity, previous epidemiological studies have not found a correlation between the presence of type 1 fimbriae and urinary tract infections (UTIs). Recently it has become clear that type 1 fimbriae exhibit several different phenotypes, due to allelic variation of the gene for the lectin subunit, FimH, and that these phenotypes are differentially distributed among fecal and UTI isolates. In this study, we have analyzed in more detail the ability of isogenic, recombinant strains of E. coli expressing fimH genes of the predominant fecal and UTI phenotypes to adhere to glycoproteins and to uroepithelial cells. Evidence was obtained to indicate that type 1 fimbriae differ in their ability to recognize various mannosides, utilizing at least two different mechanisms. All FimH subunits studied to date are capable of mediating adhesion via trimannosyl residues, but only certain variants are capable of mediating high levels of adhesion via monomannosyl residues. The ability of the FimH lectins to interact with monomannosyl residues strongly correlates with their ability to mediate E. coli adhesion to uroepithelial cells. In this way, it would be possible for certain phenotypic variants of type 1 fimbriae to contribute more than others to virulence of E. coli in the urinary tract.

Adherence of Escherichia coli to human urinary tract epithelial cells

The adherence of Escherichia coli to human uroepithelial cells obtained from midstream urine specimens of healthy women was studied. Bacteria labeled with [(3)H]uridine were used, and unattached organisms were separated from the epithelial cells by vacuum filtration with 5-mum-pore-size Nucleopore membrane filters. These techniques allowed adherence to be measured in large numbers of epithelial cells and overcame the problem of distinguishing experimental bacteria from the indigenous organisms present on uroepithelial cells. Adherence was not appreciably affected by temperature. Adherence was maximal at pH 4 to 5 and at bacterial-to-epithelial-cell ratios of 5,000 or more. The latter observation suggested that there are a limited number of receptors on the epithelial cell surface, an idea which was supported by competition experiments. Adherence occurred within 1 min and then decreased gradually or quickly, depending on the type of bacterial growth medium, to a stationary level of adherence, approximately 50% of that observed initially. The ability of epithelial cells from a single individual to bind E. coli varied in a cyclical and repetitive pattern. Adherence tended to be higher during the early phase of the menstrual cycle and diminished shortly after the time of expected ovulation; adherence frequently correlated with the value obtained on the same day of the menstrual cycle during the preceding months. Adherence was markedly enhanced by bacterial incubation in broth for 72 h and inhibited by alpha-d-mannose. These results suggest that adherence is a complex phenomenon perhaps mediated in part by bacterial pili and mannose residues on uroepithelial cells.

Adhesion to normal human uroepithelial cells of Escherichia coli from children with various forms of urinary tract infection

The ability to adhere to normal human uroepithelial cells was compared for Escherichia coli strains isolated from the urine of girls with acute pyelonephritis, acute cystitis, or asymptomatic bacteriuria, and from the stools of school children without bacteriuria. Strains from those with acute pyelonephritis had high adhesive ability, whereas strains from those with acute cystitis had intermediate and strains from girls with asymptomatic bacteriuria or from normal feces had low adhesive ability. Strains of serogroup O4K12 had good adherence regardless of origin. E. coli of the eight O groups commonly found in patients with acute pyelonephritis adhered more than did strains of other O groups. Spontaneously agglutinating strains had less adhesive ability than did the O-typable ones.

Identification of the cells underlying pacemaker activity in the guinea-pig upper urinary tract

1. The varying profile of cell types along the muscle wall of the guinea-pig upper urinary tract was examined electrophysiologically, using intracellular microelectrodes, and morphologically, using both electron and confocal microscopy. 2. Simple 'pacemaker' oscillations (frequency of 8 min-1) of the membrane potential were recorded in both the pelvi-calyceal junction (83 % of cells) and the proximal renal pelvis (15 % of cells), but never in the distal renal pelvis or ureter. When filled with the cell marker, neurobiotin, 'pacemaker' cells were spindle shaped and approximately 160 microm in length. 3. In most cells of the ureter (100 %) and in both the proximal (75 %) and distal (89 %) renal pelvis, spontaneous action potentials (frequency of 3-5 min-1) consisted of an initial spike, followed by a number of potential oscillations superimposed on a plateau phase. When filled with neurobiotin, cells firing these 'driven' action potentials, were spindle shaped and > 250 microm in length. 4. Greater than 80 % of smooth muscle cells in the pelvi-calyceal junction were 'atypical', having < 40 % of their sectional areas occupied by loosely packed contractile filaments. Most of the smooth muscle cells in the ureter (99.7 %) and both the proximal (83 %) and distal (97.5 %) renal pelvis were of 'typical' appearance in that they contained cytoskeletal and contractile elements occupying > 60 % of cross-sectional area. 5. A third type of spontaneously discharging cell fired 'intermediate' action potentials (3-4 min-1), consisting of a single spike followed by a quiescent plateau and an abrupt repolarization. These cells were morphologically similar to interstitial cells of Cajal (ICC). However, these 'ICC-like' cells were not immuno-reactive for c-Kit, the proto-oncogene for tyrosine kinase. 6. In summary, 'atypical' smooth muscle cells were predominant in the pelvi-calyceal junction and fired 'pacemaker' potentials at a frequency significantly higher than 'driven' action potentials recorded in 'typical' smooth muscle cells throughout the renal pelvis and ureter. 'Intermediate' action potentials were recorded in 'ICC-like' cells in both the pelvi-calyceal junction and renal pelvis. We suggest that these 'ICC-like' cells act as a preferential pathway, conducting and amplifying pacemaker signals to initiate action potential discharge in the driven areas of the upper urinary tract.

Expression and distribution of PIEZO1 in the mouse urinary tract

The proper function of the organs that make up the urinary tract (kidneys, ureters, bladder, and urethra) depends on their ability to sense and respond to mechanical forces, including shear stress and wall tension. However, we have limited understanding of the mechanosensors that function in these organs and the tissue sites in which these molecules are expressed. Possible candidates include stretch-activated PIEZO channels (PIEZO1 and PIEZO2), which have been implicated in mechanically regulated body functions including touch sensation, proprioception, lung inflation, and blood pressure regulation. Using reporter mice expressing a COOH-terminal fusion of Piezo1 with the sequence for the tandem-dimer Tomato gene, we found that PIEZO1 is expressed in the kidneys, ureters, bladder, and urethra as well as organs in close proximity, including the prostate, seminal vesicles and ducts, ejaculatory ducts, and the vagina. We further found that PIEZO1 expression is not limited to one cell type; it is observed in the endothelial and parietal cells of the renal corpuscle, the basolateral surfaces of many of the epithelial cells that line the urinary tract, the interstitial cells of the bladder and ureters, and populations of smooth and striated muscle cells. We propose that in the urinary tract, PIEZO1 likely functions as a mechanosensor that triggers responses to wall tension.

Role of epithelial interleukin-8 (IL-8) and neutrophil IL-8 receptor A in Escherichia coli-induced transuroepithelial neutrophil migration

Escherichia coli stimulates neutrophil migration across human uroepithelial cell layers. This study investigated the role of the neutrophil chemokine interleukin-8 (IL-8) in this process. E. coli and IL-1alpha stimulated urinary tract epithelial layers to secrete IL-8 and induced transepithelial neutrophil migration. Anti-IL-8 antibody reduced neutrophil migration across epithelial cell layers, indicating a central role for this chemokine in the migration process. Furthermore, addition of recombinant IL-8 to unstimulated cell layers was sufficient to induce migration. The IL-8 dependence of neutrophil migration was maintained after removal of soluble IL-8 by washing of the cell layers. Flow cytometry analysis with fluorescein isothiocyanate-labelled IL-8 confirmed IL-8's ability to bind to the epithelial cell surface. Indirect immunofluorescence with confocal laser scanning microscopy showed that IL-8 associated with the epithelial cell layers. Prior incubation of neutrophils with antibodies to IL-8 receptor A (IL-8RA) reduced neutrophil migration. Anti-IL-8 RB antibody had no effect on neutrophil migration. These results demonstrate that IL-8 plays a key role in E. coli- or IL-1alpha-induced transuroepithelial migration and suggest that epithelial cell-produced IL-8 interacts with IL-8RA on the neutrophil surface.

Mechanisms of Disease: specialized interstitial cells of the urinary tract--an assessment of current knowledge

Scientists interested in the smooth muscles of the urinary tract, and their control, have recently been studying cells in the interstitium of tissues that express the c-kit antigen (Kit(+) cells). These cells have morphologic features that are reminiscent of the well-described pacemaker cells in the gut, the interstitial cells of Cajal (ICC). The spontaneous contractile behavior of muscles in the urinary tract varies widely, and it is clear that urinary tract Kit(+) interstitial cells cannot be playing an identical role to that played by the ICC in the gut. Nevertheless, there is increasing evidence that they do play a role in modulating the contractile behavior of adjacent smooth muscle, and might also be involved in mediating neural control. This review outlines the properties of ICC in the gut, and gives an account of the discovery of cells in the interstitium of the main components of the urinary tract. The physiologic properties of such cells and the functional implications of their presence are discussed, with particular reference to the bladder. In this organ, Kit(+) cells are found under the lamina propria, where they might interact with the urothelium and with sensory nerves, and also between and within the smooth-muscle bundles. Confocal microscopy and calcium imaging are being used to assess the physiology of ICC and their interactions with smooth muscles. Differences in the numbers of ICC are seen in smooth muscle specimens obtained from patients with various pathologies; in particular, bladder overactivity is associated with increased numbers of these cells.

Differentiation of epithelial cells in the urinary tract

Uroplakins, cytokeratins and the apical plasma membrane were studied in the epithelia of mouse urinary tract. In the simple epithelium covering the inner medulla of the renal pelvis, no uroplakins or cytokeratin 20 were detected and cells had microvilli on their apical surface. The epithelium covering the inner band of the outer medulla became pseudostratified, with the upper layer consisting of large cells with stalks connecting them to the basal lamina. Uroplakins and cytokeratin 20 were not expressed in these cells. However, some superficial cells appeared without connections to the basal lamina; these cells expressed uroplakins Ia, Ib, II and III and cytokeratin 20, they contained sparse small uroplakin-positive cytoplasmic vesicles and their apical surface showed both microvilli and ridges. Cytokeratin 20 was seen as dots in the cytoplasm. This epithelium therefore showed partial urothelial differentiation. The epithelium covering the outer band of the outer medulla gradually changed from a two-layered to a three-layered urothelium with typical umbrella cells that contained all four uroplakins. Cytokeratin 20 was organized into a complex network. The epithelium possessed an asymmetric unit membrane at the apical cell surface and fusiform vesicles. Umbrella cells were also observed in the ureter and urinary bladder. In males and females, the urothelium ended in the bladder neck and was continued by a non-keratinized stratified epithelium in the urethra in which no urothelial cell differentiation markers were detected. We thus show here the expression, distribution and organization of specific proteins associated with the various cell types in the urinary tract epithelium.

Role of cyclin-dependent kinase inhibitors in the growth arrest at senescence in human prostate epithelial and uroepithelial cells

Cellular senescence has been proposed to be an in vitro and in vivo block that cells must overcome in order to immortalize and become tumorigenic. To characterize these pathways, we focused on changes in the cyclin-dependent kinase inhibitors and their binding partners that underlie the cell cycle arrest at senescence. As a model, we utilized normal human prostate epithelial cell (HPEC) and human uroepithelial cell (HUC) cultures. After 30-40 population doublings cells became growth-arrested in G0/1 with a threefold decrease in Cdk2-associated activity, a point defined as pre-senescence. Temporally following this growth arrest, the cells develop a senescence morphology and express senescence-associated beta-galactosidase (SA-beta-gal). Levels of p16(INK4a) and p57(KIP2) rise in HUCs during progressive passages, whereas only p16 increases in HPEC cultures. The induced expression of p57, similar to p16, produces a senescent-like phenotype. pRB, cyclin D, p19(INK4d) and p27(KIP1) decrease in both cell types. We find that p53, p21(CIP1) and p15(INK4b) are transiently elevated in HPECs and HUCs at the pre-senescent growth arrest, then return to low proliferating levels at terminal senescence. Analysis of p53, p21(CIP1), p15(INK4b), p16(INK4a), and p57(KIP2) reveals altered expression in immortalized, non-tumorigenic HPV16 E6 and E7 prostate lines and in tumorigenic prostate cancer cells. These results indicate: (i) the existence of a subset of growth inhibiting genes elevated at the onset of the senescence, (ii) a distinct class of genes involved in the maintenance of senescence, and (iii) the frequent inactivation of these pathways during immortalization.

Intestinal epithelial cells as watchdogs for the natural immune system

Intestinal epithelial cells secrete a spectrum of chemoattractant and proinflammatory cytokines after invasion by bacteria. We suggest the novel concept that epithelial cells not only act as a mechanical barrier to invasive bacteria, but that they also signal the presence of invasive pathogens to the mucosal immune and inflammatory cells.

Cultures of exfoliated epithelial cells from different locations of the human urinary tract and the renal tubular system

Exfoliated human urinary tract epithelial cells and renal tubular cells from urinary sediments of healthy adults, of urological patients and of internal patients were isolated and cultured. Cells started proliferating within 1 week after seeding a sediment. Proliferating cells formed colonies of different morphologies, designated as type-1 or type-2 cell colonies. Type-1 cell colonies showed irregular contours and spindle-like cells within the colonies. Subcultivation of type-1 cells for up to six passages was possible. Type-2 cell colonies showed smooth-edged contours and subcultivation was not possible. The epithelial character of type-1 cells was demonstrated by positive immunohistochemical staining for cytokeratin-7. In contrast to carbonic anhydrase-positive stained Madin Darby canine kidney cells (MDCK), which were used as positive controls for renal tubular cells, type-1 cells were carbonic anhydrase-negative on staining with the cobalt phosphate method. This indicates that type-1 cells were not of renal tubular origin. Type-2 cells were positively stained for carbonic anhydrase, indicating that type-2 cells were renal tubular cells. Type-2 cell colonies could be assigned to two subgroups with different cell forms. Colonies of cobblestone-like cells more often occurred than type-2 cell colonies with spindle-like cells, which are described in this study for the first time. Colonies with cobblestone-like cells formed domes (hemicysts), whereas spindle-like type-2 cell colonies did not. Cultures of urinary sediments from healthy adults, elderly multimorbid patients treated with furosemide, and urological patients with urolithiasis treated with sulfamethoxazole/trimethoprim and/or with a percutaneous nephrostomy catheter were compared. In 52% of all cultured sediments from healthy adults, in 30% of those from multimorbid patients, and in 75-80% of those from urological patients cells proliferated to colonies. The ratios of type-1 to type-2 cell colonies were 3.3:1 (healthy adults), 1.4:1 (urological patients with urolithiasis), and 1.8:1 (urological patients with urolithiasis, urine was directly collected from the renal pelvis with a percutaneous nephrostomy catheter). Successful cultures of the urinary sediments from these three groups revealed means of 3 or 4 colonies, 14 colonies, and 21 colonies, respectively. Differences in the number of colonies in relation to sex were observed only for the group of urological patients. It was shown that type-1 cells were urothelial cells, which did not show morphological differences due to their locations of origin within the urinary tract, whereas type-2 cells were probably renal tubular cells. These findings offer new aspects in the culturing of human urothelial or kidney epithelial cells with a method based on noninvasive collecting of specimens and requiring only minimal culture effort. The cultures obtained by this method can be used for in vitro studies in toxicological and clinical research.

Interstitial cell of Cajal-like cells in the upper urinary tract

Autorhythmicity in the upper urinary tract (UUT) has long been considered to arise in specialized atypical smooth muscle cells (SMC) predominately situated in the most proximal regions of the pyeloureteric system. These atypical SMC pacemakers have been thought to trigger adjacent electrically-quiescent typical SMC to fire action potentials which allow an influx of Ca2+ and the generation of muscle contraction. More recently, the presence of cells with many of the morphological, electrical and immunohistochemical characteristics of interstitial cells of Cajal (ICC), the pacemaker cells of the gastrointestinal tract, have been located in many regions of both the upper and lower urinary tract. This article reviews the evidence from the literature and from our laboratory supporting a role of both atypical SMC and ICC-like cells in the initiation and propagation of pyeloureteric peristalsis in the UUT. We propose a new model in which there are 2 populations of pacemaker cells, high frequency atypical SMC and lower frequency ICC-like cells, both of which can drive electrically-quiescent typical SMC. The relative presence of these 2 populations of pacemaker cells and the relatively-long refractoriness of typical SMC determines the decreasing frequency of contraction with distance from the renal fornix. In the absence of the proximal pacemaker drive from atypical SMC after pyeloureteral/ureteral obstruction or surgery, ICC-like cell pacemaking provides a compensatory mechanism allowing the ureter to maintain rudimentary peristaltic waves and movement of urine from the pyelon towards the bladder.

Telocytes in the urinary system

BACKGROUND

Telocytes, a new type of interstitial cells, have been identified in many organs in mammals. The present studies aimed at investigating the ultrastructure, distribution and interactions of telocytes with surrounding cells in the urinary system of rats, to confirm the existence of telocytes in kidneys, ureter and urinary bladder.

METHODS

Samples of kidney, ureter, or urinary bladder were harvested for the ultrastructure by the electron microscope. The primary culture of telocytes was performed to investigate the dynamic alterations.

RESULTS

Telocytes mainly located in the sub-capsular space of kidney, or between smooth muscle bundles and in the lamina propria of ureter and urinary bladder. Telocytes established numerous contacts with macrophages in the sub-capsular space of kidney, or with smooth muscle cells, nerve endings as well as blood capillaries in the ureter and urinary bladder. The complete morphology of telocytes with telopodes was observed clearly through the primary cell culture from the kidney tissues of rats.

CONCLUSIONS

Our data evidenced the existence of telocytes in the urinary system, which may contribute to the tissue reparation and regeneration.

About the presence of interstitial cells of Cajal outside the musculature of the gastrointestinal tract

Santiago Ramon y Cajal observed a special cell type that appeared to function as endstructures of the intrinsic nervous system in several organs. These cells were structurally and functionally further characterized in the gut musculature and named interstitial cells of Cajal (ICC). In recent years, interstitial cells have been identified in the vasculature, urinary tract, glands and other organs. Their morphologies and functions are just beginning to be clarified. It is likely that amongst them, subtypes will be discovered that warrant the classification of interstitial cells of Cajal. This "point of view" continues the discussion on the criteria that should be used to identify ICC outside the musculature of the gut.

Protein kinase C in cyclic stretch-induced nerve growth factor production by urinary tract smooth muscle cells

Cyclic stretch of cultured urinary tract smooth muscle cells has been used to mimic some of the events that occur with bladder obstruction. The stretch stimulus induces production of nerve growth factor (NGF), which has been implicated in changes in bladder innervation. Stretch-induced NGF production was blocked by actinomycin. Involvement of protein kinase C (PKC) in the stretch-induced NGF production is strongly suggested by the following observations. Phorbol ester activators of PKC mimicked the stretch response as did platelet-derived growth factor (PDGF), which acts, in part, through generation of endogenous diacylglycerols. Both stretch- and PDGF-induced NGF production were blocked by prolonged incubation with phorbol ester to downregulate PKC. Western blot analysis confirmed partial downregulation of the Ca(2+)-dependent PKC-alpha and PKC-beta 1 and near complete downregulation of the Ca(2+)-independent PKC isozymes delta, epsilon, and zeta. The involvement of PKC in transducing a physical stimulus (stretch) into a biochemical response (NGF production) has implications for novel types of therapeutic intervention in ailments such as bladder obstruction.

Identification of kit positive cells in the human urinary tract

PURPOSE

Analogous to interstitial cells of Cajal in the bowel, functional important networks of interstitial cells could have a role in the complex mechanism of central and peripheral control of urinary tract function. Recently various reports mentioned the presence of interstitial cells in different parts of the urinary tract and in different species. Since important differences among species exist, we performed immunohistochemistry on fresh frozen human tissue to study the presence of interstitial cells in the human urinary tract.

MATERIALS AND METHODS

A total of 65 tissue pieces from all levels of the urinary tract were obtained from 44 patients treated at our institution. Tissue was processed for immunohistochemistry immediately after removal. We performed immunohistochemistry for kit, connexin 43 and VRL1/TRPV2.

RESULTS

Interstitial cells immunopositive for all 3 antibodies were seen beneath the urothelium and between smooth muscle cells in all tissue pieces with slight topographical differences.

CONCLUSIONS

Together with morphological and functional data from other experiments these morphological data suggest that, as in the bowel, networks of interstitial cells might have an important role in the physiology and pathology of the urinary tract. They could be involved in pacemaking or have an integrating role through the modulation of neurotransmission and conduction of electrical impulses. Functional experiments are the next step to study these hypotheses.

Cytokine repertoire of epithelial cells lining the human urinary tract

PURPOSE

To examine the cytokine profile of epithelial cells lining the human urinary tract with the aim of differentiating between the constitutive and disease-related cytokine production in these tissues.

MATERIALS AND METHODS

Sections from the renal pelvis, ureter, bladder or urethra were obtained from 22 patients undergoing urinary tract surgery and were stained with monoclonal antibodies to interleukin(IL)-1beta, IL-4, IL-6, IL-8, interferon gamma (IFNgamma) and transforming growth factor beta (TGFbeta). Sections were classified according to the presence or absence of disease in the tissue.

RESULTS

Epithelial cells lining the renal pelvis, ureter, bladder or urethra all stained for IL-8 and TGFbeta (100%) in disease-free tissues and sections with cancer or interstitial cystitis (IC). In contrast, staining for IL-1beta, IL-4, IL-6 and IFNgamma varied with the disease state of the patient. Epithelial IL-1beta staining was absent (0%) in sections from healthy bladder, but positive in tissues with IC or cancer-associated pathology (50 to 100%). IL-6 staining was detected in the epithelial layer of several patients with IC or cancer related pathology, but only in cells with non-epithelial morphology and not in disease-free tissues. IFNgamma and IL-4 staining were only observed in patients with IC and only in cells with non-epithelial morphology.

CONCLUSIONS

The results show that epithelial cells from all parts of the urinary tract constitutively produce IL-8 and TGFbeta and suggest that the production of other cytokines varies with the disease of the patient. Constitutive cytokine production provides the basis for a rapid host response, in the defense against mucosal attack by microbes or toxic agents.

Stem cells for regeneration of urological structures

OBJECTIVES

This review focuses on advances in regenerative therapies using stem cells in urology.

METHODS

A detailed literature search was performed using the PubMed database of the National Center of Biotechnology Information. Publications of experimental investigations and clinical trials using stem cells in reconstructive urology have been summarized and critically reviewed.

RESULTS

Tissue engineering and autologous cell therapy techniques have been developed to generate prostheses for different urological tissues and organ systems. During the last decade, increasing numbers of studies have described stem cells in the context of therapeutic tools. The ability of adult and embryonic stem cells as well as progenitors to improve bladder wall architecture, improve renal tubule formation, or promote restoration of spermatogenesis or recovery of continence has been investigated in several animal models. Although results have been encouraging, only a myoblast-based therapy of incontinence has reached clinical trials.

CONCLUSIONS

Several populations of adult stem cells and progenitor cells have been studied as useful cellular sources in the treatment and reconstruction of urological organs. However, considerable basic research still needs to be performed to ensure the controlled differentiation and long-term fate of stem cells following transplantation.

Immunoanatomic dissection of the human urinary tract by monoclonal antibodies

The immunoanatomy of the human kidney and urinary tract has been analyzed by a panel of mouse anti-human monoclonal antibodies that define specific domains and structures. The differentiation antigens detected by these monoclonal antibodies represent a series of glycoproteins characteristic of different cell types. They differ from the blood group antigens and appear to be distinct from other antigens previously described within the kidney or urinary tract. The antigens recognized by these monoclonal antibodies represent an immunohistologic dissection of the human nephron. These antibodies have a broad range of potential applications in studying embryogenesis and pathogenesis of nonneoplastic and neoplastic diseases of the human kidney and urothelium.

Interaction between interstitial cells and smooth muscles in the lower urinary tract and penis

Smooth muscles in the lower urinary tract and corporal tissue exhibit spontaneous contractile activity which depends on L-type Ca(2+) channels. The mechanism underlying this activity is spontaneous electrical activity which shows varied form and property between these tissues. Recent studies revealed that interstitial cells (ICs) are widely distributed in the genitourinary system, and suggested their involvement in spontaneous muscle activity. ICs in the system are not a simple analogy of interstitial cells of Cajal (ICC) in the gut, which act as electrical pacemaker, but represent variability amongst tissues which may account for individual characteristics of each organ. In the bladder and corporal tissue, where smooth muscle cells are capable of generating spontaneous electrical activity, ICs may modulate smooth muscle activity. ICs in corporal tissue release prostaglandins via cyclooxygenase-2 (COX-2) activity and reinforce not only spontaneous but also nerve-mediated alpha-adrenergic contractions. In the bladder, their fundamental role in the integration of signals between populations of cells has been proposed, and thus changes in ICs may contribute to an overactive bladder, a pathological condition which results from increased excitability in detrusor smooth muscles. In the urethra, ICs may act as electrical pacemakers as do ICC. However, overall contractility of urethral smooth muscles does not necessarily rely on pacemaking of ICs, and thus some population of smooth muscles may also have their own excitability.