STXBP1: fast-forward to a brighter future - a patient organization perspective.

Syntaxin-binding protein 1 related disorder (STXBP1-RD) is a rare neurologic disorder associated with global neurodevelopmental delay, intellectual disability, early-onset epilepsy, motor abnormalities, and autism. The underlying pathophysiology stems from a de novo mutation in the STXBP1 gene, which codes for the STXBP1 protein. The STXBP1 protein is involved in synaptic vesicle fusion and neurotransmitter release. Pathogenic variants in the STXBP1 gene generally result in haploinsufficiency, an impairment in neurotransmitter release, and subsequent dysfunction in neuronal communication. The STXBP1 Foundation was founded in 2017 to support families of children with STXBP1-RD and accelerate the development of effective therapies and, ultimately, a cure for the disorder. The Foundation initially supported research aimed at better understanding the complex phenotypic presentation of the disease as well as the development of animal and cellular models usable by the research community to more fully characterize STXBP1 function and disease pathogenicity. In 2023, the Foundation embarked on its STXBP1 Fast Forward Strategic Plan, which includes a prospective natural history study and substantive biomarker work to drive forward the development of new precision therapies for STXBP1-RD.

STXBP1: fast-forward to a brighter future STXBP1-related disorder (STXBP1-RD) is a rare and severe brain condition. It causes delays in development, learning problems, seizures starting at an early age, movement challenges, and sometimes autism. The main problem comes from a new mutation in the STXBP1 gene, which makes a protein needed for brain cells to communicate properly. When this gene doesn't work right, there's not enough of the protein, leading to trouble with brain cell communication. To help families dealing with this disorder and speed up the search for effective therapies, the STXBP1 Foundation started in 2017. At first, they funded studies to understand the disease better and create models for testing treatments. Then, in 2023, they launched the STXBP1 Fast Forward Strategic Plan. This plan includes studying how the disorder progresses naturally and researching markers that could help develop precise treatments for STXBP1-RD.

Herpes simplex virus vector mediated gene therapy of tumor necrosis factor-α blockade for bladder overactivity and nociception in rats.

PURPOSE: We examined the effects of tumor necrosis factor-α blockade on bladder overactivity and nociception using replication defective HSV vectors expressing tumor necrosis factor-α soluble receptor. MATERIALS AND METHODS: HSV vectors expressing tumor necrosis factor-α soluble receptor or ß-galactosidase/green fluorescent protein as the control were injected into the bladder wall of female Sprague-Dawley® rats. Green fluorescent protein was observed with fluorescent microscopy in the bladder and L6 dorsal root ganglia. mRNA and protein expression of tumor necrosis factor-α, and interleukin-1ß and 6 as well as myeloperoxidase activity in the bladder were determined by quantitative reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay 4 hours after intravesical resiniferatoxin administration. c-Fos positive neurons were counted in the L6 spinal dorsal horn. Cystometry and behavioral analyses were also performed. RESULTS: Green fluorescent protein expression was confirmed in the bladder and L6 dorsal root ganglia. Resiniferatoxin administration significantly increased tumor necrosis factor-α mRNA and protein levels in the bladder in controls. Tumor necrosis factor-α mRNA was also increased in the tumor necrosis factor-α soluble receptor group, although tumor necrosis factor-α protein up-regulation was suppressed. The up-regulation of interleukin-1ß and 6 mRNA and protein levels, and the myeloperoxidase activity seen in controls were suppressed in the tumor necrosis factor-α soluble receptor group. c-Fos positive cells in the L6 spinal dorsal horn were less prominent in the tumor necrosis factor-α soluble receptor group than in controls. On cystometry the significant decrease in intercontraction intervals after resiniferatoxin infusion detected in controls was not seen in the tumor necrosis factor-α soluble receptor group. On behavioral analyses freezing behavior was significantly decreased in the tumor necrosis factor-α soluble receptor group without affecting licking behavior. CONCLUSIONS: HSV vector mediated tumor necrosis factor-α blockade gene therapy in the bladder and bladder afferent pathways decreases the bladder pain and overactivity induced by nociceptive bladder stimuli.

HSV delivery of a ligand-regulated endogenous ion channel gene to sensory neurons results in pain control following channel activation.

Persistent pain remains a tremendous health problem due to both its prevalence and dearth of effective therapeutic interventions. To maximize pain relief while minimizing side effects, current gene therapy-based approaches have mostly exploited the expression of pain inhibitory products or interfered with pronociceptive ion channels. These methods do not enable control over the timing or duration of analgesia, nor titration to analgesic efficacy. Here, we describe a gene therapy strategy that potentially overcomes these limitations by providing exquisite control over therapy with efficacy in clinically relevant models of inflammatory pain. We utilize a herpes simplex viral (HSV) vector (vHGlyRα1) to express a ligand-regulated chloride ion channel, the glycine receptor (GlyR) in targeted sensory afferents; the subsequent exogenous addition of glycine provides the means for temporal and spatial control of afferent activity, and therefore pain. Use of an endogenous inhibitory receptor not normally present on sensory neurons both minimizes immunogenicity and maximizes therapeutic selectivity.

Centralizing neurofibromatosis experimental tool knowledge with the NF Research Tools Database.

Experimental tools and resources, such as animal models, cell lines, antibodies, genetic reagents and biobanks, are key ingredients in biomedical research. Investigators face multiple challenges when trying to understand the availability, applicability and accessibility of these tools. A major challenge is keeping up with current information about the numerous tools available for a particular research problem. A variety of disease-agnostic projects such as the Mouse Genome Informatics database and the Resource Identification Initiative curate a number of types of research tools. Here, we describe our efforts to build upon these resources to develop a disease-specific research tool resource for the neurofibromatosis (NF) research community. This resource, the NF Research Tools Database, is an open-access database that enables the exploration and discovery of information about NF type 1-relevant animal models, cell lines, antibodies, genetic reagents and biobanks. Users can search and explore tools, obtain detailed information about each tool as well as read and contribute their observations about the performance, reliability and characteristics of tools in the database. NF researchers will be able to use the NF Research Tools Database to promote, discover, share, reuse and characterize research tools, with the goal of advancing NF research. Database URL: https://tools.nf.synapse.org/.

Suppression of detrusor-sphincter dyssynergia by herpes simplex virus vector mediated gene delivery of glutamic acid decarboxylase in spinal cord injured rats.

PURPOSE: We investigated whether replication defective herpes simplex virus vectors encoding genes of glutamic acid decarboxylase, the gamma-aminobutyric acid synthesis enzyme, could suppress detrusor-sphincter dyssynergia in rats with spinal cord injury. MATERIALS AND METHODS: One week after spinalization herpes simplex virus vectors expressing glutamic acid decarboxylase and green fluorescent protein were injected into the bladder wall. Spinal cord injured rats without herpes simplex virus injection (sham treated) and those injected with LacZ encoding herpes simplex virus vectors served as controls. Three weeks after viral injection we simultaneously recorded urethral and intravesical pressure in awake rats. RESULTS: In the glutamic acid decarboxylase group the urethral pressure increase during bladder contraction was significantly decreased by 77% to 79% compared with that in the sham treated and LacZ groups. Bladder activity and urethral baseline pressure did not differ among the 3 groups. Intrathecal application of the gamma-aminobutyric acid-A receptor antagonist bicuculline almost completely reversed the decrease in the urethral pressure increase during bladder contractions while intrathecal saclofen (Tocris Cookson, Ellisville, Missouri), a gamma-aminobutyric acid-B receptor antagonist, partially reversed it. In the glutamic acid decarboxylase group the mRNA of glutamic acid decarboxylase 67 was significantly increased in L6-S1 dorsal root ganglia, which is where bladder afferents originate, compared with that in the LacZ group. CONCLUSIONS: Herpes simplex virus based glutamic acid decarboxylase gene transfer to bladder afferent pathway may represent a novel approach to detrusor-sphincter dyssynergia in cases of spinal cord injury.

The therapeutic potential of gene transfer for the treatment of peripheral neuropathies.

Peripheral neuropathy is a common medical problem with numerous aetiologies. Unfortunately, for the majority of cases there is no available medical solution for the underlying cause, and the only option is to try to treat the resulting symptoms. Treatment options exist when neuropathy results in positive symptoms such as pain, but there is a significant lack of treatments for negative symptoms such as numbness and weakness. Systemic application of growth factor peptides has shown promise in protecting nerves from neuropathic insults in preclinical animal studies, but translation into human trials has been problematic and disappointing. Significant advancements have been made in the past few years in utilising gene therapy approaches to treat peripheral neuropathy by expressing neuroprotective gene products either systemically or in specific nervous tissues. For example, plasmids expressing vascular endothelial growth factor injected into muscle, or herpes-simplex-virus-based vectors expressing neurotrophin gene products delivered to dorsal root ganglion neurons, have been used to protect peripheral nerve function in animal models of diabetes-associated peripheral neuropathy. Many published studies support the feasibility of this approach, although several questions still need to be addressed as gene therapy to treat peripheral neuropathy moves out of the laboratory and into the clinic.

An HSV-based library screen identifies PP1α as a negative TRPV1 regulator with analgesic activity in models of pain.

Transient receptor potential vanilloid 1 (TRPV1) is a pronociceptive cation channel involved in persistent inflammatory and neuropathic pain. Herpes simplex virus (HSV) vector expression of TRPV1 causes cell death in the presence of capsaicin, thereby completely blocking virus replication. Here we describe a selection system for negative regulators of TRPV1 based on rescue of virus replication. HSV-based coexpression of TRPV1 and a PC12 cell-derived cDNA library identified protein phosphatase 1α (PP1α) as a negative regulator of TRPV1, mimicking the activity of "poreless" (PL), a dominant-negative mutant of TRPV1. Vectors expressing PP1α or PL reduced thermal sensitivity following virus injection into rat footpads, but failed to reduce the nocifensive responses to menthol/icilin-activated cold pain or formalin, demonstrating that the activity identified in vitro is functional in vivo with a degree of specificity. This system should prove powerful for identifying other cellular factors that can inhibit ion channel activity.

Herpes simplex-mediated gene transfer of nerve growth factor protects against peripheral neuropathy in streptozotocin-induced diabetes in the mouse.

Peripheral neuropathy is a common and debilitating complication of diabetes. In animal models, neurotrophic factors can prevent progression of the neuropathy, but adverse effects prevent systemic administration in adequate doses to treat human disease. We examined whether gene transfer with replication-defective genomic herpes simplex virus (HSV) vectors modified to express nerve growth factor (NGF) could be used to prevent progression of neuropathy in mice. Diabetes induced by streptozotocin (STZ) resulted in a sensory neuropathy manifest by a decrease in the foot sensory nerve amplitude (FSA; control = 20 +/- 0.1 microV, treated = 14 +/- 0.1 microV). Transduction of dorsal root ganglia in vivo with an HSV-based vector expressing NGF under the control of the human cytomegalovirus immediate early promoter (vector SHN) or the HSV latency active promoter 2 (vector SLN) by footpad inoculation 2 weeks after STZ administration protected against the decrease in FSA (22 +/- 1.4 microV and 21 +/- 1.7 microV, respectively) measured 4 weeks later. Injection of SHN into inguinal adipose tissue 2 weeks after onset of diabetes also prevented the decrease in FSA (20 +/- 3.3 microV). These results suggest that gene transfer with an NGF-producing herpes-based vector may prove useful in the treatment of diabetic neuropathy.

Delivery of herpes simplex virus-based vectors to the nervous system.

Gene transfer to the nervous system is an attractive option to treat a wide variety of neurological insults. The expression of trophic factor and/or antiapoptotic genes may be beneficial in halting the slow neurodegeneration in such conditions as Parkinson's disease (4,5), the rapid neuronal cell death following trauma to the brain or spinal cord (6,7), or in treating peripheral neuropathies associated with diabetes or use of chemotherapeutic agents (8,9). Introduction of dominant-negative mutant genes or antisense RNA to treat diseases such as Huntington's disease, or transfer of genes to replace lost or mutated endogenous proteins to treat disorders such as lysosomal storage diseases, may prove useful. In addition, gene transfer to overexpress endogenous antinociceptive proteins has great potential in pain management. The problem faced by all of these applications is finding a suitable methodology that will facilitate the transfer of exogenous genes to the appropriate nerve cells; virusbased vectors have proven quite efficient in transferring genes to many different cell types.

Herpes simplex virus-based nerve targeting gene therapy in pain management.

Chronic pain represents a major medical burden not only in terms of suffering but also in terms of economic costs. Traditional medical approaches have so far proven insufficient in treating chronic pain and new approaches are necessary. Gene therapy with herpes simplex virus (HSV)-based vectors offers the ability to directly target specific regions of the neuraxis involved in pain transmission including the primary afferent nociceptor. This opens up new targets to interact with that are either not available to traditional systemic drugs or cannot be adequately acted upon without substantial adverse off-target effects. Having access to the entire neuron, which HSV-based vector gene therapy enables, expands treatment options beyond merely treating symptoms and allows for altering the basic biology of the nerve. In this paper, we discuss several HSV-based gene therapy vectors that our group and others have used to target specific neuronal functions involved in the processing of nociception in order to develop new therapies for the treatment of chronic pain.

Effects of herpes simplex virus vector-mediated enkephalin gene therapy on bladder overactivity and nociception.

We previously reported the effects of herpes simplex virus (HSV) vector-mediated enkephalin on bladder overactivity and pain. In this study, we evaluated the effects of vHPPE (E1G6-ENK), a newly engineered replication-deficient HSV vector encoding human preproenkephalin (hPPE). vHPPE or control vector was injected into the bladder wall of female rats 2 weeks prior to the following studies. A reverse-transcription PCR study showed high hPPE transgene levels in L6 dorsal root ganglia innervating the bladder in the vHPPE group. The number of freezing behaviors, which is a nociceptive reaction associated with bladder pain, was also significantly lower in the vHPPE group compared with the control group. The number of L6 spinal cord c-fos-positive cells and the urinary interleukin (IL)-1ß and IL-6 levels after resiniferatoxin (RTx) administration into the bladder of the vHPPE group were significantly lower compared with those of the control vector-injected group. In continuous cystometry, the vHPPE group showed a smaller reduction in intercontraction interval after RTx administration into the bladder. This antinociceptive effect was antagonized by naloxone hydrochloride. Thus, the HSV vector vHPPE encoding hPPE demonstrated physiological improvement in visceral pain induced by bladder irritation. Gene therapy may represent a potentially useful treatment modality for bladder hypersensitive disorders such as bladder pain syndrome/interstitial cystitis.

Premature aging-related peripheral neuropathy in a mouse model of progeria.

Peripheral neuropathy is a common aging-related degenerative disorder that interferes with daily activities and leads to increased risk of falls and injury in the elderly. The etiology of most aging-related peripheral neuropathy is unknown. Inherited defects in several genome maintenance mechanisms cause tissue-specific accelerated aging, including neurodegeneration. We tested the hypothesis that a murine model of XFE progeroid syndrome, caused by reduced expression of ERCC1-XPF DNA repair endonuclease, develops peripheral neuropathy. Nerve conduction studies revealed normal nerve function in young adult (8 week) Ercc1(-/Δ) mice, but significant abnormalities in 20 week-old animals. Morphologic and ultrastructural analysis of the sciatic nerve from mutant mice revealed significant alterations at 20 but not 8 weeks of age. We conclude that Ercc1(-/Δ) mice have accelerated spontaneous peripheral neurodegeneration that mimics aging-related disease. This provides strong evidence that DNA damage can drive peripheral neuropathy and offers a rapid and novel model to test therapies.

Gene therapy for bladder overactivity and nociception with herpes simplex virus vectors expressing preproenkephalin.

Interstitial cystitis/painful bladder syndrome (IC/PBS) is a major challenge to treat. We studied the effect of targeted and localized expression of enkephalin in afferent nerves that innervate the bladder by gene transfer using replication-defective herpes simplex virus (HSV) vectors in a rat model of bladder hyperactivity and pain. Replication-deficient HSV vectors encoding preproenkephalin, which is a precursor for Met- and Leu-enkephalin, or control vector encoding the lacZ reporter gene, were injected into the bladder wall of female rats. After viral vector injection, quantitative polymerase chain reaction showed high preproenkephalin transgene levels in bladder and dorsal root ganglia innervating the bladder in enkephalin vector-treated animals. Functionally, enkephalin vector-treated animals showed reductions in bladder hyperactivity and nociceptive behavior induced by intravesical application of capsaicin; however, vector-mediated expression of enkephalin did not alter normal voiding. This antinociceptive effect of enkephalin gene therapy was antagonized by naloxone hydrochloride administration. Together, our results with HSV vectors encoding preproenkephalin demonstrated physiological improvement in visceral pain induced by bladder irritation. Thus, gene therapy may represent a potentially useful treatment modality for bladder hypersensitive disorders such as IC/PBS.

Gene therapy applications for the treatment of neuropathic pain.

Neuropathic pain is notoriously difficult to treat; currently available pharmaceutical drugs result in moderate analgesia in approximately a third of patients. As our understanding of the biological processes involved in the establishment and maintenance of neuropathic pain increases, so does the development of novel treatment options. Significant advancements have been made in the past few years in gene transfer, a very powerful potential therapy that can be used to directly target affected areas of the neuraxis or body tissues involved in neuropathic pain. Candidate gene products include directly analgesic proteins as well as proteins that interfere with pain-associated biochemical changes in nerve or other tissues underlying the disease process.

Herpes vector-mediated expression of proenkephalin reduces bone cancer pain.

We examined whether a herpes simplex virus vector that expresses human proenkephalin could be used to attenuate nociception in a model of bone cancer pain in mice. Osteolytic sarcoma cells were implanted into the medullary space of the right femur, followed by a subcutaneous inoculation of a replication-defective herpes simplex virus vector expressing human proenkephalin (vector SHPE) or a lacZ-expressing control vector (vector SHZ). SHPE-inoculated mice demonstrated a significant, naltrexone-reversible decrease in pain-related behavior assessed during open-field motor activity. These results suggest that gene transfer with an enkephalin-expressing vector may be used to treat pain resulting from cancer in bone.