Herpes Simplex Virus Vector-Mediated Gene Delivery of Poreless TRPV1 Channels Reduces Bladder Overactivity and Nociception in Rats

Abstract

Increased afferent excitability has been proposed as an important pathophysiology of interstitial cystitis/ bladder pain syndrome (IC/BPS) and overactive bladder (OAB). In this study, we investigated whether herpes simplex virus (HSV) vectors encoding poreless TRPV1, in which the segment in C terminus of TRPV1 receptor is deleted, suppress bladder overactivity and pain behavior using a rat model of chemical cystitis. Replication-defective HSV vectors encoding poreless TRPV1 were injected into the bladder wall of adult female Sprague-Dawley rats. Additionally, recombinant HSV virus (vHG) vectors were injected as control. Cystometry (CMG) under urethane anesthesia was performed 1 week after viral injection to evaluate bladder overactivity induced by resiniferatoxin (RTx, a TRPV1 agonist). RTx-induced nociceptive behavior such as licking (lower abdominal licking) and freezing (motionless head-turning) was observed 2 weeks after viral injection. GFP expression in L4/L6/S1 dorsal root ganglia and the bladder as well as cFos-positive cells in the L6 spinal cord dorsal horn were also evaluated 2 weeks after viral injection. In CMG, the poreless TRPV1 vector-treated group showed a significantly smaller reduction in intercontraction intervals and voided volume after RTx infusion than the vHG-treated control group. The number of the RTx-induced freezing events was significantly decreased in the poreless TRPV1 group than in the vHG group, whereas there was no significant difference of the number of RTx-induced licking events between groups. The number of c-Fos-positive cells in the DCM and SPN regions of the L6 spinal dorsal horn was significantly smaller in the poreless TRPV1 group than in the vHG group. Our results indicated that HSV vector-mediated gene delivery of poreless TRPV1 had a therapeutic effect on TRPV1-mediated bladder overactivity and pain behavior. Thus, the HSV vector-mediated gene therapy targeting TRPV1 receptors could be a novel modality for the treatment of OAB and/or hypersensitive bladder disorders such as IC/BPS.

The effect of herpes simplex virus vector‐mediated gene therapy of protein phosphatase 1α on bladder overactivity and nociception

“…Injection of the HSV‐GFP vector into the bladder wall resulted in the presence of GFP‐positive cells within the bladder but also neurons within the L6 and S1 DRGs, but not in L4 DRG, which is the level that does not innervate the bladder . These results demonstrate that the HSV vectors can deliver and express therapeutic genes in the bladder and its primary sensory neurons, but not in afferent neurons projecting to other organs after the bladder inoculation, as similarly reported in our previous studies . Therefore, it suggested that HSV vector‐based gene therapy could be organ‐specific in nature thereby avoiding systemic adverse effects.…”

“…Hence, HSV‐based vectors can be applied to the PNS, being transfected to the targeted sensory neurons to express the therapeutic product . In fact, we previously showed that non‐replicating HSV vectors‐mediated gene delivery was an organ‐specific and beneficial treatment tool in several rat cystitis models …”

Pathophysiology of refractory overactive bladder

“…In a rat model, TRPV1 was demonstrated to be a potential therapeutic target for future treatment of OAB. 57 Gene delivery of poreless TRPV1 channels via a herpes simplex virus vector has shown therapeutic effectiveness in rats with OAB …”

“…55,56 In a rat model, TRPV1 was demonstrated to be a potential therapeutic target for future treatment of OAB. 57 Gene delivery of poreless TRPV1 channels via a herpes simplex virus vector has shown therapeutic effectiveness in rats with OAB. 57 Within the spinal cord, c-fos protein expression in the dorsal root ganglia is elevated by noxious and non-noxious stimuli.…”

“…57 Gene delivery of poreless TRPV1 channels via a herpes simplex virus vector has shown therapeutic effectiveness in rats with OAB. 57 Within the spinal cord, c-fos protein expression in the dorsal root ganglia is elevated by noxious and non-noxious stimuli. Activation of afferent nerves in the bladder can lead to elevated c-fos protein in the spinal cords of rats.…”