Promoter-targeted anti-nociceptive HSV-1 vectors have differential effects on pain based on the neuronal population targeted
Year: 2015
Type: dissertation
Abstract: Herpes simplex virus-1 (HSV-1) is a neurotropic virus capable of infecting sensory neurons through their termini at any site on the body. Upon infection, the HSV-1 genome persists in nuclei within sensory ganglia for the life of the host. Replication-defective HSV-1 vectors allow for the efficient transduction of diverse populations of sensory neurons without risk of herpetic disease and therefore represent an ideal gene therapy vehicle for the treatment of peripheral neurological diseases, including chronic pain. To evaluate the potential of HSV-1 vectors to treat pain, a set of replication-defective HSV-1 vectors was generated, driving the expression of an anti-nociceptive product (GlyRIS) from neuronal promoters to target expression to distinct neuronal populations. Specifically, the TRPV1 promoter was used to target heat-sensitive nociceptors, and the NF200 promoter was used to target large diameter Aβ-fibers which may be recruited for pain signaling after injury or inflammation. The ubiquitously expressed CMV promoter was used as a control. As expected, when these vectors were used to transduce cultured DRG cells, the neuronal promoters largely expressed in neuronal cells only, while the CMV promoter expressed in neuronal and support cells. For pain studies, vectors were injected under the skin of the right hind footpad in rats. After nine days, baseline thermal and mechanical withdrawal thresholds were taken before and after the application of the ligand ivermectin, activating vector-delivered GlyRIS. TRPV1-GlyRIS transduced rats and to a lesser extent CMV-GlyRIS transduced rats showed increased thermal withdrawal thresholds on the transduced side after ligand administration. Resiniferatoxin (RTX) was then injected to ablate TRPV1+ neurons and induce mechanical allodynia. After 20 days, all RTX-injected rats showed increased thermal withdrawal thresholds with a loss of dependence on vector injection and ligand administration, consistent with TRPV1+ neuron ablation. All RTX-injected rats developed bilateral mechanical allodynia, except for the NF200-GlyRIS transduced rats (Aβ-targeted) which demonstrated decreased mechanical allodynia on the transduced side relative to the contralateral side after ivermectin administration. These differential effects on nociception represent the functional outcome of differentially targeted anti-nociceptive HSV-1 vectors and support the use of promoter-targeting to express transgenes in specific neuronal subpopulations.
Author: Mark F. Doyal
Language: English
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W889691837