The project investigates the mechanisms of VEGF-related signaling in neurogenesis of urological chronic pelvic pain syndromes (UCPPS), and neural plasticity of the neural pathways innervating the lower urinary tract. Urological Chronic Pelvic Pain Syndrome is a complex and multifactorial disorder characterized by voiding and/or sexual dysfunction, visceral hyperalgesia, and chronic pelvic pain (CPP). Previous animal studies from our laboratory established that peripheral neurogenic inflammation together with central sensitization play a role in generation and maintenance of UCPPS symptoms. Recent study from the MAPP network confirmed that VEGF could be one of the potential urinary biomarkers of UCPPS. Specifically, patients with UCCPS had significantly higher levels of urinary VEGF and VEGF receptors than healthy controls. Additionally, pain severity was significantly associated with increased urinary VEGF suggesting that it may serve as a clinically useful diagnostic marker for UCPPS. Despite these novel clinical data, the sites and mechanisms of VEGF action in the CNS centers controlling micturition, effects on excitability of peripheral and central neurons innervating the lower urinary tract (LUT) are still unknown. Therefore, this project is designed to evaluate the mechanistic involvement of VEGF in bladder pain and voiding dysfunction to provide scientific justification and “proof-of-concept” data for designing clinical trials of anti-VEGF treatments to alleviate LUTS and bladder pain in UCPPS.
The project studies mechanosensation and mechanotransduction in human bladder smooth muscle cells (BSMC), and abnormal response of the urinary bladder to physiological stretch in detrusor overactivity. Activation of mechanosensitive receptors on bladder smooth muscle cells (BSMC) is the first step in initiation of mechanotransduction in the bladder wall with subsequent transmission of the signal to sensory neurons and, further, to the central nervous system. Pathological changes in bladder mechanosensation and signal transduction between BSMC and afferent nerves lead to the development of detrusor overactivity (DO), a co-symptom of many disorders including overactive bladder (OAB), obstructed bladder, diabetic overactivity, and bladder pain syndrome. Our data provided evidence that detrusor mechanosensitivity depends on the function of mechano-gated two-pore domain (K2P, KCNK) K+ channels. We confirmed that TREK-1 is a predominantly expressed K2P channel in the human detrusor, and its expression and function are diminished in patients with idiopathic DO. Understanding the precise mechanisms of mechanotransduction in normal and diseased urinary bladder will provide a knowledge foundation for the development of new pharmacological interventions and innovative strategies for patients with overactive LUTS.
Multiple sclerosis (MS) is an auto-inflammatory disease of the central nervous system (CNS) that affects approximately 400,000 people in the United States alone, and more than 2.1 million people worldwide. Lower urinary tract symptoms (LUTS) are present in 70–80% of MS patients, and include urinary frequency, urgency, incontinence, nocturia, incomplete bladder emptying, weak stream, and retention of urine. We recently characterized a new mouse model of neurogenic bladder dysfunction induced by a coronavirus. The virus triggers acute inflammation in the CNS followed by progressive demyelination in the brain and spinal cord. CIE mice develop a significant neurologic deficit followed by neurogenic bladder dysfunction that is comparable with neurogenic LUTS observed in MS patients. Several neural mechanisms contributing to neurogenic LUTS in the CIE model were determined in our laboratory. They include morphological changes in the neuronal centers controlling micturition, activation of gliosis at the lesion sites in the spinal cord, increased expression of pro-inflammatory cytokines during acute inflammation in the CNS, and an increase of purinergic component of nerve-mediated bladder contractions associated with changes in the bladder mucosa. The CIE model provides a unique opportunity for the comparison of neurogenic LUTS in remissive, chronic and relapsing-remitting types of MS development. The project is focused on uncovering the mechanisms by which neurodegenerative changes in the CNS affect plasticity of the neural pathways innervating the LUT in order to improve the assessment, diagnosis, and treatment of LUTS in patients with MS.
Patients with urological chronic pelvic pain syndrome (UCPPS) experience chronic pelvic pain (CPP) and lower urinary tract symptoms (LUTS). The UCPPS symptoms are closely associated with nociceptive sensitization in the nervous system, which underlies visceral allodynia and hyperalgesia. Previous studies suggested that afferent hypersensitivity in bladder-projecting sensory neurons plays an important role in the generation and the maintenance of UCPPS symptoms, especially bladder pain and urinary frequency. We have found that Gq-GPCR activation in satellite glial cells (SGCs) in the sensory ganglia decreases afferent sensitivity in lumbar nociceptive assays, a promising and highly innovative approach to alleviate the symptoms of bladder overactivity and pain. The current work focuses on 1) developing experimental approaches for targeted activation of Gq-GPCR signaling pathways in sensory SGCs; 2) assessing the changes in lumbosacral bladder afferent sensitivity following glial Gq-GPCR activation; and 3) evaluating the glial activation-induced changes in LUTS and visceral hypersensitivity in vivo and in mouse models of UCPPS. Gq-coupled Designer Receptors Exclusively Activated by Designer Drugs (Gq-DREADD) is used to selectively activate Gq-GPCR signaling cascades in lumbosacral sensory SGCs via targeted adeno-associated virus (AAV) delivery. Afferent sensitivity and bladder functions are evaluated in vivo by well-established and clinically-relevant visceral nociceptive assays and urodynamic assays. This project aims to characterize the role of SGC Gq-GPCR signaling in regulating visceral nociception in vivo as well as test its therapeutic potential to reverse pain and voiding dysfunction in UCPPS patients.
We are investigating the effects on bladder function of two specific anti-cancer chemotherapies, vincristine and doxorubicin, which are known to cause the side effects of neurotoxicity and myotoxicity, respectively. Surveying childhood cancer survivors treated with these agents for symptoms of bladder dysfunction and studying bladder physiology in a murine model of vincristine and doxorubicin exposure will allow us to take the first steps in understanding chemotherapy-induced pediatric bladder dysfunction. We have observed that over 40% of childhood cancer survivors treated with these two agents demonstrate signs and symptoms of bladder dysfunction. Additionally, early translational investigation in the laboratory of altered bladder physiology in a murine model of doxorubicin exposure demonstrates detrusor smooth muscle dysfunction by dysregulation in the detrusor contractile-relaxation mechanisms and have led to our current proposed mechanisms underlying doxorubicin-induced detrusor smooth muscle dysfunction. Determining the clinical extent of this problem as well as understanding the mechanisms behind this bladder dysfunction can go towards future goals of treatment and prevention. Data obtained from this work will benefit childhood cancer survivors globally.