State of the art in intravesical therapy for lower urinary tract symptoms

Intravesical therapy is the routine first-line treatment for effectively delaying or preventing the recurrence of bladder cancer. This route of drug administration has also shown tremendous promise in the treatment of interstitial cystitis/painful bladder syndrome (IC/PBS) and potentially overactive bladder to justify investments for further improvements. This review takes a bird's eye view into the current status of intravesical therapy, with emphasis on liposomal nanoparticles, in diseases associated with lower urinary tract symptoms (LUTS). Ongoing efforts to advance the field of intravesical drug delivery include development of sustained-release drug implants and efforts to improve delivery of biotechnological products including large protein acting as neurotoxins and small interfering RNAs.     

Sex differences in lower urinary tract biology and physiology

Females and males differ significantly in gross anatomy and physiology of the lower urinary tract, and these differences are commonly discussed in the medical and scientific literature. However, less attention is dedicated to investigating the varied development, function, and biology between females and males on a cellular level. Recognizing that cell biology is not uniform, especially in the lower urinary tract of females and males, is crucial for providing context and relevance for diverse fields of biomedical investigation. This review serves to characterize the current understanding of biological sex differences between female and male lower urinary tracts, while identifying areas for future research. First, the differences in overall cell populations are discussed in the detrusor smooth muscle, urothelium, and trigone. Second, the urethra is discussed, including anatomic discussions of the female and male urethra followed by discussions of cellular differences in the urothelial and muscular layers. The pelvic floor is then reviewed, followed by an examination of the sex differences in hormonal regulation, the urinary tract microbiome, and the reticuloendothelial system. Understanding the complex and dynamic development, anatomy, and physiology of the lower urinary tract should be contextualized by the sex differences described in this review.     

Sex-related differences in SLIGRL-induced pruritus in mice

Aims

Pruritus is a common symptom of skin diseases, and is associated with impaired sleep quality and a considerable reduction in the patient's quality of life. Recently, it was reported that there are sex-specific differences in scratching behavior in chronic pruritus patients. Namely, female chronic pruritus patients scratch more and have significantly more scratch lesions than male patients. However, few animal studies have examined sex-related differences in scratching behavior. Thus, the present work investigated sex-related differences in animal pruritus using pruritogens, which are often used to create experimental animal models of itching.

Main methods

Acute pruritus was induced in ICR mice by a single intradermal injection of histamine, 4-methylhistamine, serotonin, compound 48/80, substance P (SP), or the proteinase-activated receptor-2 (PAR-2)-activating peptide SLIGRL-NH₂. Chronic pruritus was induced by 5 weeks of the repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB) to BALB/c mice.

Key findings

Female mice showed significantly higher scratching counts in SLIGRL-NH₂-induced pruritus than male mice. Conversely, there was no obvious sex-related difference in scratching behavior for the other pruritogens examined.

Significance

These results indicate that sex-related differences may exist in the pruritogen-responsive neurons that transmit the itch signal induced by SLIGRL-NH₂, but not by histamine or 5-HT.     

Sex-related differences in energy balance in response to caloric restriction

Sex-related differences in energy balance were studied in young Wistar rats fed standard chow pellets either ad libitum or in restricted amounts (60% of ad libitum intake) for 100 days. Caloric intake, indirect calorimetry, organ and adipose tissue weights, energy efficiency, liver mitochondrial respiration rate, and brown adipose tissue (BAT) uncoupling protein-1 (UCP1) content were measured. Ad libitum-fed females showed greater oxygen consumption (Vo(2)) and carbon dioxide production (Vco(2)) and lower energy efficiency than males. Caloric restriction induced a chronic drop of Vo(2) and Vco(2) in females but not in males over the period studied. Restricted females showed a better conservation of metabolic active organ mass and a greater decrease in adipose depots than restricted males. Moreover, changes of BAT size and UCP1 content suggest that BAT may be the main cause responsible for sex differences in the response of energy balance to caloric restriction. In conclusion, our results indicate that females under caloric restriction conditions deactivate facultative thermogenesis to a greater degree than males. This ability may have obvious advantages for female survival and therefore the survival of the species when food is limiting.     

Sex-related difference in food-anticipatory activity of mice

The expression of food-anticipatory activity (FAA) is induced by restricted feeding (RF), and its entrainment requires food-entrainable oscillators, the neuroanatomical basis of which is currently unclear. Although RF impacts various hormones, sex-related differences in FAA are unclear. 'Here, we report significantly more food-anticipatory wheel-running activity in male than in female mice during RF. In parallel with the sex-related difference in FAA, male and female mice display different food intake and body weight in response to RF. Since gonadal hormones could be involved in the sex-specific difference in FAA, we compared sham and gonadectomized male and female wild-type mice. In gonadectomized mice, the sex difference in FAA was abolished, indicating a role for gonadal hormones in FAA. Further, plasma concentrations of the hormone ghrelin were higher in female than in male mice during ad libitum (AL) feeding, and RF induced a temporal advance in its peak in both sexes. RF also shifted the expression peak of the circadian gene mPer1 in the hippocampus and liver, although no sex difference was found in either the level or the cyclic phase of its expression. Per1^Brdm1 mutant mice were still sexually dimorphic for FAA, but diminished FAA was noted in both male and female Per2^Brdm1 mutant mice. In summary, our results imply that gonadal hormones contribute to the sex difference in FAA, possibly through modulating ghrelin activity.     

Sensory irritation response in mice to sulfur dust.

The potential of sulfur dust to produce sensory irritation was evaluated in mice. Male Swiss--Webster mice were exposed by head-only inhalation to 106, 263, or 451 mg/m3 sulfur dust aerosol at room temperature. Breathing frequency and patterns were monitored before, during, and after exposure to evaluate the animal's sensory irritation response to the test atmosphere. Group average breathing rates were decreased 7 and 17% below pretest values in mice exposed to 106 and 263 mg/m3, respectively; however, breathing patterns appeared normal, indicating that there was no sensory irritation. Mice exposed to 451 mg/m3 showed an increase in breathing frequency of 7%, with 1/4 mice displaying very slight signs of pulmonary (deep lung) irritation. Some of the mice in the low- and high-dose groups exhibited signs of slight eye irritation immediately after exposure, but all mice were normal 1 day later. On the basis of these findings, exposure to sulfur dust up to 451 mg/m3 did not produce any sensory or upper airway irritation in mice.     

Central neural stimulation of respiration in unanesthetized decerebrate cats.

A previously reported central neural respiratory control process was restudied in unanesthetized decerebrate cats during spontaneous breathing, and during conditions of constant chemical stimulation where phrenic nerve activity was used to quantitate respiratory output. Respiration was increased by carotid sinus nerve stimulation. The pattern of respiration was examined at the cessation of such stimulation. In spontaneously breathing animals, active hyperventilation (HV) was followed by hyperpnea for up to 30 s and never by apnea. Passive HV was always followed by apnea. In animals with controlled chemical conditions, the transient at the end of stimulation consisted of two components, the first an immediate decrease in respiratory output and the second a slow decrease with a period of over 5 m. It is suggested that a facilitatory feedback process, probably located in the reticular activating system, maintains respiratory output for some time after cessation of a stimulus. This study duplicates the results of previous studies and shows that no area of the brain above the pons is required for the mechanism's operation.     

NK(1) receptor and its interaction with NMDA receptor in spinal c-fos expression after lower urinary tract irritation

The role of neurokinin 1 (NK(1)) receptor and possible interaction between NK(1) and N-methyl-D-aspartic acid (NMDA) glutamatergic receptors were investigated on spinal c-fos expression after lower urinary tract irritation with acetic acid infusion in rats. At both levels of the first (L(1)) and sixth lumbar (L(6)) spinal cord, where most of hypogastric nerve and pelvic nerve afferent terminals project, respectively, the selective NK(1) receptor antagonist CP-99,994 dose dependently reduced the total number of c-fos protein (Fos)-positive cells. However, CP-100,263, the enantiomer of CP-99,994 with a very low affinity for NK(1) receptor, did not have any effect on the total number of Fos-positive cells. Coadministration of a low dose (1 mg/kg) of CP-99,994 and NMDA receptor antagonist (MK-801), either of which alone did not affect c-fos expression, significantly inhibited c-fos expression at both levels of the spinal cord. Regarding regional differences, the number of Fos-positive cells decreased significantly at all regions of the L(6) level, but only at the dorsal horn of the L(1) level. These results indicate that NK(1) receptor is involved in spinal c-fos expression after lower urinary tract irritation and that NK(1) and NMDA receptors have a synergistic interaction in the spinal processing of nociceptive input from the lower urinary tract.     

Adrenergic innervation of the lower urinary tract in cattle

Studies were carried out on 8 sexually immature male calves. Sections of the ureters, urinary bladder, and urethra were cut with a freezing microtome and the method of Ky?s?la et al. (1980) was used to visualize the adrenergic nerve fibres. It was found that bovine ureters possessed weak innervation; most of the nerves was located in the muscular membrane, and only in the paravesical part, sparse nerve fibres were found in the submucosa of this one. Apex of the urinary bladder was more weakly supplied with the adrenergic nerves than the corpus, whereas bladder's trigonum and cervix possessed numerous nerve fibres in both muscular and submucosal membranes. The distribution pattern of adrenergic nerves in the urethra was similar to that of urinary bladder's cervix. The presence of adregeneric nerve fibres was found in submucosal layer of both the urinary bladder and the urethra. Part of the nerves was connected with blood vessels of the organs under study.     

Psychological aspects of lower urinary tract infections in women.

OBJECTIVE--To determine whether women with the urethral syndrome can be distinguished from those with urinary tract infection by case notes, clinical symptoms, or psychiatric state. DESIGN--Longitudinal survey of consecutive women presenting with dysuria and frequency. SETTING--General practice and community. SUBJECTS--58 patients with the urethral syndrome and 44 patients with a urinary tract infection, mean age 39.9 years. MAIN OUTCOME MEASURES--Results of analysis of serial midstream urine specimens, patients'' self rated physical symptoms and responses to 60 item general health questionnaire at presentation and after resolution of symptoms, and results of psychiatric assessment with the clinical psychiatric interview. RESULTS--4 of 42 patients with a urinary tract infection had recently changed sexual partner compared with none of 58 with the urethral syndrome. Dysuria and nocturia were more common in patients with urinary tract infections than those with the urethral syndrome (mean (SD) score for dysuria 5.37 (2.39) v 4.57 (2.13), p less than 0.05; nocturia in 39/44 (88%) patients v 40/58 (69%), chi 2 = 5.5, p less than 0.02). Both groups showed transient high levels of distress which resolved with the physical symptoms, but no psychiatric difference distinguished them. CONCLUSION--The urethral syndrome is not associated with increased psychiatric morbidity.     

Ventilatory response to hypoxia in unanesthetized newborn kittens

We studied the ventilatory response to hypoxia in 11 unanesthetized newborn kittens (n = 54) between 2 and 36 days of age by use of a flow-through system. During quiet sleep, with a decrease in inspired O2 fraction from 21 to 10%, minute ventilation increased from 0.828 +/- 0.029 to 1.166 +/- 0.047 l.min-1.kg-1 (P less than 0.001) and then decreased to 0.929 +/- 0.043 by 10 min of hypoxia. The late decrease in ventilation during hypoxia was related to a decrease in tidal volume (P less than 0.001). Respiratory frequency increased from 47 +/- 1 to 56 +/- 2 breaths/min, and integrated diaphragmatic activity increased from 14.9 +/- 0.9 to 20.2 +/- 1.4 arbitrary units; both remained elevated during hypoxia (P less than 0.001). Younger kittens (less than 10 days) had a greater decrease in ventilation than older kittens. These results suggest that the late decrease in ventilation during hypoxia in the newborn kitten is not central but is due to a peripheral mechanism located in the lungs or respiratory pump and affecting tidal volume primarily. We speculate that either pulmonary bronchoconstriction or mechanical uncoupling of diaphragm and chest wall may be involved.     

Biphasic ventilatory response to hypoxia in unanesthetized rats

To determine the role of postinspiratory inspiratory activity of the diaphragm in the biphasic ventilatory response to hypoxia in unanesthetized rats, we examined diaphragmatic activity at its peak (DI), at the end of expiration (DE), and ventilation in adult unanesthetized rats during poikilocapnic hypoxia (10 % O2) sustained for 20 min. Hypoxia induced an initial increase in ventilation followed by a consistent decline. Tidal volume (VT), frequency of breathing (fR), DI and DE at first increased, then VT and DE decreased, while fR and DI remained enhanced. Phasic activation of the diaphragm (DI-DE) increased significantly at 10, 15 and 20 min of hypoxia. These results indicate that 1) the ventilatory response of unanesthetized rats to sustained hypoxia has a typical biphasic character and 2) the increased end-expiratory activity of the diaphragm limits its phasic inspiratory activation, but this increase cannot explain the secondary decline in tidal volume and ventilation.     

Advances in stem cell therapy for the lower urinary tract

Lower urinary tract diseases are emotionally and financially burdensome to the individual and society. Current treatments are ineffective or symptomatic. Conversely, stem cells (SCs) are regenerative and may offer long-term solutions. Among the different types of SCs, bone marrow SCs (BMSCs) and skeletal muscle-derived SCs (SkMSCs) have received the most attention in pre-clinical and clinical trial studies concerning the lower urinary tract. In particular, clinical trials with SkMSCs for stress urinary incontinence have demonstrated impressive efficacy. However, both SkMSCs and BMSCs are difficult to obtain in quantity and therefore neither is optimal for the eventual implementation of SC therapy. On the other hand, adipose tissue-derived SCs (ADSCs) can be easily and abundantly obtained from "discarded" adipose tissue. Moreover, in several head-on comparison studies, ADSCs have demonstrated equal or superior therapeutic potential compared to BMSCs. Therefore, across several different medical disciplines, including urology, ADSC research is gaining wide attention. For the regeneration of bladder tissues, possible differentiation of ADSCs into bladder smooth muscle and epithelial cells has been demonstrated. For the treatment of bladder diseases, specifically hyperlipidemia and associated overactive bladder, ADSCs have also demonstrated efficacy. For the treatment of urethral sphincter dysfunction associated with birth trauma and hormonal deficiency, ADSC therapy was also beneficial. Finally, ADSCs were able to restore erectile function in various types of erectile dysfunction (ED), including those associated with diabetes, hyperlipidemia, and nerve injuries. Thus, ADSCs have demonstrated remarkable therapeutic potentials for the lower urinary tract.     

Novel mechanisms of early upper and lower urinary tract patterning regulated by RetY1015 docking tyrosine in mice

Mutations in the receptor tyrosine kinase RET are associated with congenital anomalies of kidneys or urinary tract (CAKUT). RET tyrosine Y1015 is the docking site for PLCγ, a major regulator of RET signaling. Abrogating signaling via Y1015 causes CAKUT that are markedly different than renal agenesis in Ret-null or RetY1062F mutant mice. We performed analysis of Y1015F mutant upper and lower urinary tracts in mice to delineate its molecular and developmental roles during early urinary tract formation. We found that the degeneration of the common nephric ducts (CND), the caudal-most Wolffian duct (WD) segment, depends on Y1015 signals. The CNDs in Y1015F mutants persist owing to increased proliferation and reduced apoptosis, and showed abundance of phospho-ERK-positive cells. In the upper urinary tract, the Y1015 signals are required for proper patterning of the mesonephros and metanephros. Timely regression of mesonephric mesenchyme and proper demarcation of mesonephric and metanephric mesenchyme from the WD depends on RetY1015 signaling. We show that the mechanism of de novo ectopic budding is via increased ERK activity due to abnormal mesenchymal GDNF expression. Although reduction in GDNF dosage improved CAKUT it did not affect delayed mesenchyme regression. Experiments using whole-mount immunofluorescence confocal microscopy and explants cultures of early embryos with ERK-specific inhibitors suggest an imbalance between increased proliferation, decreased apoptosis and increased ERK activity as a mechanism for WD defects in RetY1015F mice. Our work demonstrates novel inhibitory roles of RetY1015 and provides a possible mechanistic explanation for some of the confounding broad range phenotypes in individuals with CAKUT.     

Distribution of serotonin-immunoreactive paraneurons in the lower urinary tract of dogs

Morphological and quantitative studies were made on serotonin-containing paraneurons throughout the lower urinary tract in male and female dogs. Using an anti-serotonin antiserum, the cells were consistently demonstrated to be dispersed in the epithelium from the vesico-urethral junction to the external urethral ostium. They occurred most frequently in the urethra proximal to the urogenital diaphragm in both sexes. The total number of the serotonin-immunoreactive cells in the urethra was estimated to be 36.2 X 10(4) (SD 9.9 X 10(4] in the male (n = 3) and 15.6 X 10(4) (SD 2.1 X 10(4] in the female (n = 3). Besides the urethra, the prostate and vaginal vestibule contained several serotonin-immunoreactive cells. The urethral serotonin cells were basically bipolar basal-granulated cells that extended the basal cytoplasm to the basement membrane and reached the lumen with an apical process. Modified cell shapes were, however, also frequent, and included bifurcated apical and/or basal processes or a laterally directed basal process. Occasional serotonin cells possessed a threadlike basal process with varicosities and a terminal bouton, reminiscent of a neuronal process. Immunoreactivity for chromogranin A, a carrier protein common to endocrine paraneurons, was demonstrated in all of the urethral serotonin cells. The chromogranin A-immunoreactive granules accumulated more densely in the basal and perinuclear regions of the cell. It is hypothesized that the serotonin-immunopositive paraneurons may receive chemical and/or physical information from urine and, in response to it, secrete serotonin which presumably causes the contraction of the musculature of the urethra.