Role of neurogenic inflammation in local communication in the visceral mucosa

Autonomic Nervous System Dysfunction Is Related to Chronic Prostatitis/Chronic Pelvic Pain Syndrome

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common and non-lethal urological condition with painful symptoms. The complexity of CP/CPPS's pathogenesis and lack of efficient etiological diagnosis results in incomplete treatment and recurrent episodes, causing long-term mental and psychological suffering in patients. Recent findings indicate that the autonomic nervous system involves in CP/CPPS, including sensory, sympathetic, parasympathetic, and central nervous systems. Neuro-inflammation and sensitization of sensory nerves lead to persistent inflammation and pain. Sympathetic and parasympathetic alterations affect the cardiovascular and reproductive systems and the development of prostatitis. Central sensitization lowers pain thresholds and increases pelvic pain perception in chronic prostatitis. Therefore, this review summarized the detailed processes and mechanisms of the critical role of the autonomic nervous system in developing CP/CPPS. Furthermore, it describes the neurologically relevant substances and channels or receptors involved in this process, which provides new perspectives for new therapeutic approaches to CP/CPPS.

Differential Influences of Endogenous and Exogenous Sensory Neuropeptides on the ATP Metabolism by Soluble Ectonucleotidases in the Murine Bladder Lamina Propria

Bladder urothelium and suburothelium/lamina propria (LP) have prominent sensory and transducer functions with the active participation of afferent neurons and urothelium-derived purine mediators such as adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine (ADO). Effective concentrations of purines at receptor targets depend significantly on the extracellular degradation of ATP by ectonucleotidases (ENTDs). We recently reported the regulated release of soluble ENTDs (s-ENTDs) in the LP and the consequent degradation of ATP to ADP, AMP, and ADO. Afferent neurons in the LP can be activated by urothelial ATP and release peptides and other transmitters that can alter the activity of cells in their vicinity. Using a murine decentralized ex vivo detrusor-free bladder model, 1,N6-etheno-ATP (eATP) as substrate, and sensitive HPLC-FLD methodologies, we found that exogenous neuropeptides calcitonin gene-related peptide (CGRP), substance P (Sub P), neurokinin A (NKA), and pituitary adenylate cyclase-activating polypeptide [PACAP (1-38)] all increased the degradation of eATP by s-ENTDs that were released in the LP spontaneously and/or during bladder filling. Using antagonists of neuropeptide receptors, we observed that endogenous NKA did not modify the ATP hydrolysis by s-ENTDs, whereas endogenous Sub P increased both the constitutive and distention-induced release of s-ENTDs. In contrast, endogenous CGRP and PACAP (1-38) increased the distention-induced, but not the spontaneous, release of s-ENTDs. The present study puts forward the novel idea that interactions between peptidergic and purinergic signaling mechanisms in the LP have an impact on bladder excitability and functions by regulating the effective concentrations of adenine purines at effector cells in the LP.

Molecular Mechanism Operating in Animal Models of Neurogenic Detrusor Overactivity: A Systematic Review Focusing on Bladder Dysfunction of Neurogenic Origin

Neurogenic detrusor overactivity (NDO) is a severe lower urinary tract disorder, characterized by urinary urgency, retention, and incontinence, as a result of a neurologic lesion that results in damage in neuronal pathways controlling micturition. The purpose of this review is to provide a comprehensive framework of the currently used animal models for the investigation of this disorder, focusing on the molecular mechanisms of NDO. An electronic search was performed with PubMed and Scopus for literature describing animal models of NDO used in the last 10 years. The search retrieved 648 articles, of which reviews and non-original articles were excluded. After careful selection, 51 studies were included for analysis. Spinal cord injury (SCI) was the most frequently used model to study NDO, followed by animal models of neurodegenerative disorders, meningomyelocele, and stroke. Rats were the most commonly used animal, particularly females. Most studies evaluated bladder function through urodynamic methods, with awake cystometry being particularly preferred. Several molecular mechanisms have been identified, including changes in inflammatory processes, regulation of cell survival, and neuronal receptors. In the NDO bladder, inflammatory markers, apoptosis-related factors, and ischemia- and fibrosis-related molecules were found to be upregulated. Purinergic, cholinergic, and adrenergic receptors were downregulated, as most neuronal markers. In neuronal tissue, neurotrophic factors, apoptosis-related factors, and ischemia-associated molecules are increased, as well as markers of microglial and astrocytes at lesion sites. Animal models of NDO have been crucial for understanding the pathophysiology of lower urinary tract (LUT) dysfunction. Despite the heterogeneity of animal models for NDO onset, most studies rely on traumatic SCI models rather than other NDO-driven pathologies, which may result in some issues when translating pre-clinical observations to clinical settings other than SCI.

Effect of Intratrigonal Botulinum Toxin in Patients with Bladder Pain Syndrome/Interstitial Cystitis: A Long-Term, Single-Center Study in Real-Life Conditions

The high percentage of treatment failures seen in patients with bladder pain syndrome/interstitial cystitis (BPS/IC) managed conservatively frequently demands invasive treatment options. We aimed to evaluate the long-term efficacy and adverse events of intratrigonal botulinum toxin injection in such circumstances, as well as to determine possible predictors of response to toxin treatment. A retrospective cohort study included 47 female BPS/IC patients treated with onabotulinum toxin A (OnabotA) in a tertiary hospital between the years 2009 and 2022. All patients received 100 U of OnabotA in ten injections limited to the trigonal area. Patients were divided into three groups based on their treatment response as responders, non-responders and lost to follow-up due to non-medical reasons. The clinical and surgical records of the individuals were retrieved, including the 10-point visual analogue scale (VAS), the number of treatments, the time between injections, and the age at the first injection. A total of 25 patients (>50% of the cohort) were long-term responders, but none of the evaluated parameters was a predictor for this circumstance: age, pain intensity, or duration of improvement following the injection. The time between injections was stable (around 1 year). No severe adverse events were registered. The intratrigonal injection of botulinum toxin in patients with BPS/IC was an effective and safe long-term treatment for patients' refractory to conservative forms of treatment. Age, basal pain intensity, and time to injection request did not predict long-term response to OnaBotA.

Urothelial progenitors in development and repair

Urothelium is a specialized multilayer epithelium that lines the urinary tract from the proximal urethra to the kidney. In addition to proliferation and differentiation during development, urothelial injury postnatally triggers a robust regenerative capacity to restore the protective barrier between the urine and tissue. Mounting evidence supports the existence of dedicated progenitor cell populations that give rise to urothelium during development and in response to injury. Understanding the cellular and molecular basis for urothelial patterning and repair will inform tissue regeneration therapies designed to ameliorate a number of structural and functional defects of the urinary tract. Here, we review the current understanding of urothelial progenitors and the signaling pathways that govern urothelial development and repair. While most published studies have focused on bladder urothelium, we also discuss literature on upper tract urothelial progenitors. Furthermore, we discuss evidence supporting existence of context-specific progenitors. This knowledge is fundamental to the development of strategies to regenerate or engineer damaged or diseased urothelium.

Defining urge as an uncontrolled micturition explains pathogenesis, informs cure and helps solve the burgeoning OAB crisis

BACKGROUND

Parallel with the demographic ageing crisis, is a disabling overactive bladder (OAB) crisis (urgency/frequency/nocturia), 30% prevalence in older women, pathogenesis stated as unknown and, according to some learned societies, incurable.

HYPOTHESIS/AIMS

To review International Continence Society and Integral System paradigms to test our thesis that OAB per se is not a pathological condition, rather, a prematurely activated uncontrolled micturition; pathogenesis being anatomical damage in a nonlinear feedback control system comprising cortical and peripheral (muscle/ligament) components.

METHODS

We examined studies from basic science, anatomy, urodynamics, ultrasonic and video xrays, ligament repairs, from which we created a nonlinear binary model of bladder function. We applied a Chaos Theory feedback equation, Xnext  = Xc(1 - X) to test our hypothesis against existing concepts and hypotheses for OAB pathogenesis.

RESULTS

The bladder has ONLY two modes, EITHER closed OR open (micturition). Closure is reflexly controlled cortically and peripherally: muscles contracting against ligaments stretch the vagina to suppress afferent signals to micturate from urothelial stretch receptors. "OAB" can be caused by anatomical damage anywhere in the model, by childbirth or age-weakened ligaments, which can be repaired to cure all three OAB symptoms. Urodynamic "DO" graphs are interpreted anatomically and by the feedback equation.

CONCLUSION

OAB is in crisis. Our thesis of OAB as an uncontrolled micturition from anatomical defects in the bladder control system provides fresh directions for further development of new treatments, nonsurgical and surgical, to help break the crisis and bring hope and cure to 600 million women sufferers.

Transient receptor potential vanilloid type 4 (TRPV4) in urinary bladder structure and function

Bladder pain syndrome (BPS)/interstitial cystitis (IC) is a urologic, chronic pelvic pain syndrome characterized by pelvic pain, pressure, or discomfort with urinary symptoms. Symptom exacerbation (flare) is common with multiple, perceived triggers including stress. Multiple transient receptor potential (TRP) channels (TRPA1, TRPV1, TRPV4) expressed in the bladder have specific tissue distributions in the lower urinary tract (LUT) and are implicated in bladder disorders including overactive bladder (OAB) and BPS/IC. TRPV4 channels are strong candidates for mechanosensors in the urinary bladder and TRPV4 antagonists are promising therapeutic agents for OAB. In this perspective piece, we address the current knowledge of TRPV4 distribution and function in the LUT and its plasticity with injury or disease with an emphasis on BPS/IC. We review our studies that extend the knowledge of TRPV4 in urinary bladder function by focusing on (i) TRPV4 involvement in voiding dysfunction, pelvic pain, and non-voiding bladder contractions in NGF-OE mice; (ii) distention-induced luminal ATP release mechanisms and (iii) involvement of TRPV4 and vesicular release mechanisms. Finally, we review our lamina propria studies in postnatal rat studies that demonstrate: (i) the predominance of the TRPV4+ and PDGFRα+ lamina propria cellular network in early postnatal rats; (ii) the ability of exogenous mediators (i.e., ATP, TRPV4 agonist) to activate and increase the number of lamina propria cells exhibiting active Ca2+ events; and (iii) the ability of ATP and TRPV4 agonist to increase the rate of integrated Ca2+ activity corresponding to coupled lamina propria network events and the formation of propagating wavefronts.

Flavonoid Nobiletin Attenuates Cyclophosphamide-Induced Cystitis in Mice through Mechanisms That Involve Inhibition of IL-1β Induced Connexin 43 Upregulation and Gap Junction Communication in Urothelial Cells

Bladder inflammatory diseases cause various urinary symptoms, such as urinary frequency and painful urination, that impair quality of life. In this study, we used a mouse model of cyclophosphamide (CYP)-induced bladder inflammation and immortalized human urothelial (TRT-HU1) cells to explore the preventive potential of nobiletin (NOB), a polymethoxylated flavone enriched in citrus fruit peel, and investigate its mechanism of action in the bladder. Prophylaxis with PMF90 (60% NOB) attenuated the development of bladder inflammation and urinary symptoms in CYP-treated mice. PMF90 also reduced the upregulation of connexin 43 (Cx43), a major component of gap junction channels, in the bladder mucosa of CYP-treated mice. Stimulation of TRT-HU1 cells with the pro-inflammatory cytokine IL-1β increased Cx43 mRNA and protein expression and enhanced gap junction coupling-responses that were prevented by pre-treatment with NOB. In urothelium-specific Cx43 knockout (uCx43KO) mice, macroscopic signs of bladder inflammation and changes in voiding behavior induced by CYP treatment were significantly attenuated when compared to controls. These findings indicate the participation of urothelial Cx43 in the development of bladder inflammation and urinary symptoms in CYP-treated mice and provide pre-clinical evidence for the preventive potential of NOB through its anti-inflammatory effects on IL-1β signaling and urothelial Cx43 expression.

The innervation of the bladder, the pelvic floor, and emotion: A review

The innervation of the pelvic region is complex and includes extensive neurologic pathways. The higher centres' organisation determining the pelvic floor and organs' function remains a challenge understanding the physiological and pain mechanisms. Psychological and emotional factors have a profound influence on the pelvic floor and organ dysfunction such as LUTS. LUTS are associated with stress, depression, and anxiety. Neuroception is a subconscious neuronal system for detecting threats and safety and might explain the permanent disturbance of higher brain centres maintaining functional urological and gastrointestinal disorders and sphincter dysfunction.

Molecular pathways underlying tissue injuries in the bladder with ketamine cystitis

Ketamine cystitis (KC) is a chronic bladder inflammation leading to urinary urgency, frequency, and pain. The pathogenesis of KC is complicated and involves multiple tissue injuries in the bladder. Recent studies indicated that urothelium disruption, lamina propria fibrosis and inflammation, microvascular injury, neuropathological alterations, and bladder smooth muscle (BSM) abnormalities all contribute to the pathogenesis of KC. Ketamine has been shown to induce these tissue injuries by regulating different signaling pathways. Ketamine can stimulate antiproliferative factor, adenosine triphosphate, and oxidative stress to disrupt urothelium. Lamina propria fibrosis and inflammation are associated with the activation of cyclooxygenase-2, nitric oxide synthase, immunoglobulin E, and transforming growth factor β1. Ketamine contributes to microvascular injury via the N-methyl-D aspartic receptor (NMDAR), and multiple inflammatory and angiogenic factors such as tumor necrosis factor α and vascular endothelial growth factor. For BSM abnormalities, ketamine can depress the protein kinase B, extracellular signal-regulated kinase, Cav1.2, and muscarinic receptor signaling. Elevated purinergic signaling also plays a role in BSM abnormalities. In addition, ketamine affects neuropathological alterations in the bladder by regulating NMDAR- and brain-derived neurotrophic factor-dependent signaling. Inflammatory cells also contribute to neuropathological changes via the secretion of chemical mediators. Clarifying the role and function of these signaling underlying tissue injuries in the bladder with KC can contribute to a better understanding of the pathophysiology of this disease and to the design of effective treatments for KC.

Biomaterial-assisted drug delivery for interstitial cystitis/bladder pain syndrome treatment

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic and painful bladder condition afflicting patients with increased urinary urgency and frequency as well as incontinence. Owing to the elusive pathogenesis of IC/BPS, obtaining effective therapeutic outcomes remains challenging. Current administrational routes such as intravesical-bladder injection improve the treatment efficacy and reduce systemic side effects. However, the bladder permeability barrier hinders drug penetration into the bladder wall to meet the desired therapeutic expectation. These issues can be addressed by encapsulating drugs into biomaterials. When appropriately exploited, they would increase the drug dwelling time in the bladder, enhance the penetration of mucosa and improve the therapeutic response of IC/BPS. In this review, we first elucidate the pathogenesis and animal models of IC/BPS. Then, we highlight recent representative biomaterial-assisted drug delivery systems for IC/BPS treatment. Finally, we discuss the challenges and outlook for further developing biomaterial-based delivery systems for IC/BPS management.

Application of Adult and Pluripotent Stem Cells in Interstitial Cystitis/Bladder Pain Syndrome Therapy: Methods and Perspectives

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a multifactorial, chronic disease without definite etiology characterized by bladder-related pelvic pain. IC/BPS is associated with pain that negatively affects the quality of life. There are various therapeutic approaches against IC/BPS. However, no efficient therapeutic agent against IC/BPS has been discovered yet. Urothelium dysfunction is one of the key factors of IC/BPS-related pathogenicity. Stem cells, including adult stem cells (ASCs) and pluripotent stem cells (PSCs), such as embryonic stem cells (ESCs) and induced PSCs (iPSCs), possess the abilities of self-renewal, proliferation, and differentiation into various cell types, including urothelial and other bladder cells. Therefore, stem cells are considered robust candidates for bladder regeneration. This review provides a brief overview of the etiology, pathophysiology, diagnosis, and treatment of IC/BPS as well as a summary of ASCs and PSCs. The potential of ASCs and PSCs in bladder regeneration via differentiation into bladder cells or direct transplantation into the bladder and the possible applications in IC/BPS therapy are described in detail. A better understanding of current studies on stem cells and bladder regeneration will allow further improvement in the approaches of stem cell applications for highly efficient IC/BPS therapy.

A Synoptic Overview of Neurovascular Interactions in the Foot

Diabetes is a worldwide public health concern as it is associated with various complications. One of the major complications of diabetes is diabetic foot syndrome that results in catastrophic events such as ulceration and amputation. Therefore, the main four strategies of diabetic foot care involve risk prediction, prevention, and early diagnosis and prompt intervention. The drivers of ulceration are multifactorial, and importantly, include microcirculatory changes in the diabetic skin. Cutaneous microcirculation on the foot is greatly influenced by the small fibers which mediate thermal sensation and pain perception in addition to sympathetic activities such as thermoregulation and vasodilation. The interdependence between the neurovascular elements means with the loss of small fiber functions, the corresponding microcirculatory responses may be compromised. Thus, it can be hypothesized that the impairment of the microcirculation may follow the order of the corresponding small fiber nerve dysfunction or vice versa. In this review, select neurovascular investigations that inform the cutaneous microcirculatory and small fiber nerve function in response to pain, cold, and heat and pressure stimuli are reviewed and discussed in this order of sensory loss: the loss of pain, cold, warmth, touch and deep pressure sensation. We also discuss the neurological and vascular characteristics of each of these neurovascular responses. This review highlights the influence of small fibers on cutaneous microcirculation and the need for prospective studies that can determine the course of microcirculatory impairment over time. This, in turn, may help clarify the exact role of microcirculatory changes in the pathway of ulceration. The insights from this review can be pertinent to understand key microcirculatory disturbances and given that the microcirculatory impairment develops at an early stage, relevant interventions can be implemented to possibly reverse or regress the course of the disease. Therefore, knowledge of the neurovascular interactions aids to map the disease progression for early diagnosis and prevention of adverse complications.

The Botulinum Treatment of Neurogenic Detrusor Overactivity: The Double-Face of the Neurotoxin

Botulinum neurotoxin (BoNT) can counteract the highly frequent involuntary muscle contractions and the uncontrolled micturition events that characterize the neurogenic detrusor overactivity (NDO) due to supra-sacral spinal cord lesions. The ability of the toxin to block the neurotransmitter vesicular release causes the reduction of contractions and improves the compliance of the muscle and the bladder filling. BoNT is the second-choice treatment for NDO once the anti-muscarinic drugs have lost their effects. However, the toxin shows a time-dependent efficacy reduction up to a complete loss of activity. The cellular mechanisms responsible for BoNT effects exhaustion are not yet completely defined. Similarly, also the sites of its action are still under identification. A growing amount of data suggest that BoNT, beyond the effects on the efferent terminals, would act on the sensory system recently described in the bladder mucosa. The specimens from NDO patients no longer responding to BoNT treatment displayed a significant increase of the afferent terminals, likely excitatory, and signs of a chronic neurogenic inflammation in the mucosa. In summary, beyond the undoubted benefits in ameliorating the NDO symptomatology, BoNT treatment might bring to alterations in the bladder sensory system able to shorten its own effectiveness.

Painful interactions: Microbial compounds and visceral pain

Visceral pain, characterized by abdominal discomfort, originates from organs in the abdominal cavity and is a characteristic symptom in patients suffering from irritable bowel syndrome, vulvodynia or interstitial cystitis. Most organs in which visceral pain originates are in contact with the external milieu and continuously exposed to microbes. In order to maintain homeostasis and prevent infections, the immune- and nervous system in these organs cooperate to sense and eliminate (harmful) microbes. Recognition of microbial components or products by receptors expressed on cells from the immune and nervous system can activate immune responses but may also cause pain. We review the microbial compounds and their receptors that could be involved in visceral pain development.

Is there an appropriate strategy for treating co-morbid irritable bowel syndrome and bladder pain syndrome?

INTRODUCTION

Two of the most frequent components of chronic pelvic pain syndrome (CPPS) are irritable bowel syndrome (IBS) and bladder pain syndrome (BPS), characterized by considerable overlapping symptoms and pathophysiology. Currently, its management is challenging meaning there is high the demand for novel efficient therapeutics to aid patient care and to tackle the socioeconomic burden of IBS and BPS. As there are presently no sufficient treatment strategies, identifying the mechanisms that result in their main symptoms is the opportunity for developing appropriate therapies. Areas covered: Herein, the authors explore the potential common treatment strategies for co-morbid IBS and BPS and highlight the absolute need for further research of these deliberating clinical entities. Expert opinion: In the future, the authors summise that the discovery of predictive molecular biomarkers combined with clinical phenotypic categorization will likely allow for more definitive differentiation of patients and thus for better treatment options. Furthermore, it has been suggested that effective IBS treatment strategies would be of great value to co-morbid IBS and BPS therapy.