Transient Receptor Potential Vanilloid Subfamily Member 1 Research Articles

Dual Role of TRPV1 Channels in Cerebral Stroke: An Exploration from a Mechanistic and Therapeutic Perspective.

Transient receptor potential vanilloid subfamily member 1 (TRPV1) has been strongly implicated in the pathophysiology of cerebral stroke. However, the exact role and mechanism remain elusive. TPRV1 channels are exclusively present in the neurovascular system and involve many neuronal processes. Numerous experimental investigations have demonstrated that TRPV1 channel blockers or the lack of TRPV1 channels may prevent harmful inflammatory responses during ischemia-reperfusion injury, hence conferring neuroprotection. However, TRPV1 agonists such as capsaicin and some other non-specific TRPV1 activators may induce transient/slight degree of TRPV1 channel activation to confer neuroprotection through a variety of mechanisms, including hypothermia induction, improving vascular functions, inducing autophagy, preventing neuronal death, improving memory deficits, and inhibiting inflammation. Another factor in capsaicin-mediated neuroprotection could be the desensitization of TRPV1 channels. Based on the summarized evidence, it may be plausible to suggest that TPRV1 channels have a dual role in ischemia-reperfusion-induced cerebral injury, and thus, both agonists and antagonists may produce neuroprotection depending upon the dose and duration. The current review summarizes the dual function of TRPV1 in ischemia-reperfusion-induced cerebral injury models, explains its mechanism, and predicts the future.

137 Light-mediated Vagus Nerve Stimulation Inhibits Pro-inflammatory Cytokine Production in Acute Endotoxemia

INTRODUCTION: Vagus nerve stimulation (VNS) is a form of neuromodulation being explored to treat chronic inflammatory conditions by activating the inflammatory reflex, an arc reducing proinflammatory cytokine release through efferent cholinergic signaling. Current VNS approaches are primarily invasive and use electricity, but alternatives may improve vagal fiber specificity and eliminate surgical risks. Red-light optogenetics, a biological tool utilizing red light-activatable channelrhodopsins (ReaChR), can selectively activate genetically-modified neurons transdermally with light. Here, we show that ReaChR activation of cholinergic vagal fibers reduces cytokine production in a model of acute inflammation. METHODS: Vagus nerve cholinergic fibers were selectively activated using ReaChR expressed on choline acetyltransferase-expressing (ChAT) fibers in transgenic ChAT-ReaChR mice. Sensory afferent vagal fibers were activated in a separate cohort of transient receptor potential vanilloid subfamily member 1 (TRPV1)-ReaChR mice. Lipopolysaccharide (LPS) was injected intraperitoneally under anesthesia to induce acute endotoxemia, as measured by elevated tumor necrosis factor-alpha (TNFa). A 635nm fiber optic was targeted onto an isolated, cervical vagus for optogenetic VNS post-LPS administration. RESULTS: Selective ReaChR activation of cholinergic fibers in the cervical vagus nerve stimulates the inflammatory reflex to inhibit splenic TNFa production to bacterial LPS (ChAT-ReaChR: 1.27 ± 1.44 pg/ug; control: 4.26 ± 0.97 pg/ug, p < 0.001), but no significant differences were observed in serum (ChAT-ReaChR: 538 ± 216 pg/ml; littermate: 447 ± 206 pg/ml, p = 0.81). In contrast to efferent activation, ReaChR stimulation of afferent subsets (TRPV1+) failed to show cytokine regulation in splenic nor in serum .Approximate 20% baseline heart rate drop was seen during both ChAT+ and TRPV1+ fiber excitation, but only cholinergic activation sustained bradycardia throughout the stimulation period. CONCLUSIONS: Red-light optogenetic activation of cholinergic vagal fibers reduces splenic inflammatory cytokine production in murine endotoxemia and holds potential as a non-invasive, light-mediated VNS approach.

Improvement effect of Shegan Mahuang Decoction on rats with cold-induced asthma based on TRPV1/NRF-1/mtTFA pathway

This study investigated the therapeutic effect of Shegan Mahuang Decoction(SGMHD) on cold-induced asthma in rats and explored its underlying mechanism. Seventy-two healthy male SD rats of specific pathogen free(SPF) grade were randomly divided into a blank group, a model group, a positive control group(dexamethasone, 0.4 mg·kg~(-1)), and low-, medium-, and high-dose SGMHD groups(3.2, 6.4, and 12.8 g·kg~(-1)). The blank group received saline, while the other groups were sensitized by intraperitoneal injection of ovalbumin(OVA) solution. Subsequently, the rats were placed in a cold chamber adjustable to 0-2 ℃, and OVA solution was ultrasonically nebulized to induce cold-induced asthma in rats. After three weeks of treatment, the general behaviors of rats were observed. Hematoxylin-eosin(HE) staining was used to evaluate pathological changes in lung tissues, periodic acid-Schiff(PAS) staining assessed mucin changes, and Masson staining was performed to examine collagen deposition. Enzyme-linked immunosorbent assay(ELISA) was used to measure the levels of the inflammatory factors interleukin-4(IL-4) and vascular endothelial growth factor(VEGF) in serum and bronchoalveolar lavage fluid(BALF). Real-time quantitative polymerase chain reaction(RT-PCR) was employed to assess the mRNA expression levels of transient receptor potential vanilloid subfamily member 1(TRPV1), nuclear respiratory factor 1(NRF-1), and mitochondrial transcription factor A(mtTFA) in lung tissues. Western blot was used to measure the protein expression levels of TRPV1, NRF-1, and mtTFA in lung tissues. Compared with the blank group, the model group exhibited signs of rapid respiration, increased frequency of defecation with looser stools, and disheveled and dull fur. Pathological results showed significant infiltration of inflammatory cells in lung tissues, narrowing of bronchial lumens, increased mucin secretion, and enhanced collagen deposition in the model group. Additionally, the levels of IL-4 and VEGF in serum and BALF were significantly elevated, and the mRNA and protein expression levels of TRPV1, NRF-1, and mtTFA in lung tissues were significantly increased. Compared with the model group, SGMHD improved the behaviors of rats, alleviated pathological changes in lung tissues, mucin production, and collagen deposition, significantly decreased the levels of IL-4 and VEGF in serum and BALF, and reduced the mRNA expression levels of TRPV1, NRF-1, and mtTFA in lung tissues, with the medium-dose SGMHD group showing the most significant effect. Moreover, the protein expression levels of TRPV1, NRF-1, and mtTFA in lung tissues were also reduced, with the medium-dose SGMHD group exhibiting the most significant effect. In conclusion, this study demonstrates that SGMHD can alleviate airway inflammation and inhibit airway remodeling in cold-induced asthma rats. These effects may be associated with the modulation of the TRPV1/NRF-1/mtTFA signaling pathway.

Beyond Thermal Sensation: Roles of Transient Receptor Potential Vanilloid Subfamily Member 1 and Spicy Food in Cardiometabolic Diseases

Beyond Thermal Sensation: Roles of Transient Receptor Potential Vanilloid Subfamily Member 1 and Spicy Food in Cardiometabolic Diseases

Nogo-A Induced Polymerization of Microtubule Is Involved in the Inflammatory Heat Hyperalgesia in Rat Dorsal Root Ganglion Neurons.

The microtubule, a major constituent of cytoskeletons, was shown to bind and interact with transient receptor potential vanilloid subfamily member 1 (TRPV1), and serves a pivotal role to produce thermal hyperalgesia in inflammatory pain. Nogo-A is a modulator of microtubule assembly and plays a key role in maintaining the function of TRPV1 in inflammatory heat pain. However, whether the microtubule dynamics modulated by Nogo-A in dorsal root ganglion (DRG) neurons participate in the inflammatory pain is not elucidated. Here we reported that the polymerization of microtubules in the DRG neurons, as indicated by the acetylated α-tubulin, tubulin polymerization-promoting protein 3 (TPPP3), and microtubule numbers, was significantly elevated in the complete Freund’s adjuvant (CFA) induced inflammatory pain. Consistent with our previous results, knock-out (KO) of Nogo-A protein significantly attenuated the heat hyperalgesia 72 h after CFA injection and decreased the microtubule polymerization via up-regulation of phosphorylation of collapsin response mediator protein 2 (CRMP2) in DRG. The colocalization of acetylated α-tubulin and TRPV1 in DRG neurons was also reduced dramatically in Nogo-A KO rats under inflammatory pain. Moreover, the down-regulation of TRPV1 in DRG of Nogo-A KO rats after injection of CFA was reversed by intrathecal injection of paclitaxel, a microtubule stabilizer. Furthermore, intrathecal injection of nocodazole (a microtubule disruptor) attenuated significantly the CFA-induced inflammatory heat hyperalgesia and the mechanical pain in a rat model of spared nerve injury (SNI). In these SNI cases, the Nogo-A and acetylated α-tubulin in DRG were also significantly up-regulated. We conclude that the polymerization of microtubules promoted by Nogo-A in DRG contributes to the development of inflammatory heat hyperalgesia mediated by TRPV1.

ASIC2 Synergizes with TRPV1 in the Mechano-Electrical Transduction of Arterial Baroreceptors.

Mechanosensitive ion channels (MSCs) are key molecules in the mechano-electrical transduction of arterial baroreceptors. Among them, acid-sensing ion channel 2 (ASIC2) and transient receptor potential vanilloid subfamily member 1 (TRPV1) have been studied extensively and documented to play important roles. In this study, experiments using aortic arch-aortic nerve preparations isolated from rats revealed that both ASIC2 and TRPV1 are functionally necessary, as blocking either abrogated nearly all pressure-dependent neural discharge. However, whether ASIC2 and TRPV1 work in coordination remained unclear. So we carried out cell-attached patch-clamp recordings in HEK293T cells co-expressing ASIC2 and TRPV1 and found that inhibition of ASIC2 completely blocked stretch-activated currents while inhibition of TRPV1 only partially blocked these currents. Immunofluorescence staining of aortic arch-aortic adventitia from rats showed that ASIC2 and TRPV1 are co-localized in the aortic nerve endings, and co-immunoprecipitation assays confirmed that the two proteins form a compact complex in HEK293T cells and in baroreceptors. Moreover, protein modeling analysis, exogenous co-immunoprecipitation assays, and biotin pull-down assays indicated that ASIC2 and TRPV1 interact directly. In summary, our research suggests that ASIC2 and TRPV1 form a compact complex and function synergistically in the mechano-electrical transduction of arterial baroreceptors. The model of synergism between MSCs may have important biological significance beyond ASIC2 and TRPV1.

Heartburn sensation in nonerosive reflux disease: pattern of superficial sensory nerves expressing TRPV1 and epithelial cells expressing ASIC3 receptors.

The underlying causes of heartburn, characteristic symptom of gastroesophageal reflux disease (GERD), remain incompletely understood. Superficial afferent innervation of the esophageal mucosa in nonerosive reflux disease (NERD) may drive nociceptive reflux perception, but its acid-sensing role has not yet been established. Transient receptor potential vanilloid subfamily member-1 (TRPV1), transient receptor potential melastatin 8 (TRPM8), and acid-sensing ion channel 3 (ASIC3) are regulators of sensory nerve activity and could be important reflux-sensing receptors within the esophageal mucosa. We characterized TRPV1, TRPM8, and ASIC3 expression in esophageal mucosa of patients with GERD. We studied 10 patients with NERD, 10 with erosive reflux disease (ERD), 7 with functional heartburn (FH), and 8 with Barrett's esophagus (BE). Biopsies obtained from the distal esophageal mucosa were costained with TRPV1, TRPM8, or ASIC3, and CGRP, CD45, or E-cadherin. RNA expression of TRPV1, TRPM8, and ASIC3 was assessed using qPCR. Patients with NERD had significantly increased expression of TRPV1 on superficial sensory nerves compared with ERD (P = 0.028) or BE (P = 0.017). Deep intrapapillary nerve endings did not express TRPV1 in all phenotypes studied. ASIC3 was exclusively expressed on epithelial cells most significantly in patients with NERD and ERD (P ≤0.0001). TRPM8 was expressed on submucosal CD45+ leukocytes. Superficial localization of TRPV1-immunoreactive nerves in NERD, and increased ASIC3 coexpression on epithelial cells in NERD and ERD, suggests a mechanism for heartburn sensation. Esophageal epithelial cells may play a sensory role in acid reflux perception and act interdependently with TRPV1-expressing mucosal nerves to augment hypersensitivity in patients with NERD, raising the enticing possibility of topical antagonists for these ion channels as a therapeutic option.NEW & NOTEWORTHY We demonstrate for the first time that increased pain perception in patients with nonerosive reflux disease likely results from expression of acid-sensitive channels on superficial mucosal afferents and esophageal epithelial cells, raising the potential for topical therapy.

Treatments for Childhood Atopic Dermatitis: an Update on Emerging Therapies.

Atopic dermatitis (AD) is generally considered a T helper type 2-dominated disease. Pediatric AD is usually less severe than adult AD, but it may present as moderate to severe lesions that are inadequately managed by current modalities including emollients/moisturizers, topical corticosteroids (TCSs), topical calcineurin inhibitors (TCIs), and even systemic immunosuppressants (such as cyclosporine, azathioprine, methotrexate, and mycophenolate mofetil). In addition, systemic immunosuppressants are often not recommended for childhood AD by the current guidelines due to their toxicities. Therefore, there is still an unmet need for a safe and effective long-term therapy for pediatric AD patients whose disease is inadequately controlled or who are intolerant to current treatments. The emerging therapeutics for AD focuses on intervening in the inflammatory pathway by targeting specific cytokines/chemokines or their receptors. Monoclonal antibodies against immunoglobulin E (IgE), interleukin (IL)-4 receptor subunit α, IL-5, IL-13, IL-31 receptor subunit α, IL-33, and thymic stromal lymphopoietin (TSLP) have been evaluated clinically for AD. Encouraging results have been reported for many of the biologics, of which the most exciting is dupilumab. Other emerging systemic therapies include small molecules such as baricitinib, abrocitinib, upadacitinib, and tradipitant. Several novel topical agents are under clinical investigation for the treatment of AD, including topical phosphodiesterase 4 (PDE4) inhibitors, Janus kinase (JAK) inhibitors, aryl hydrocarbon receptor (AhR) modulating agents, and transient receptor potential vanilloid subfamily member 1 (TRPV1) antagonists. Accompanied by thorough characterization of different phenotype and endotype subsets, the application of precision medicine could provide new prospects for the optimal treatment of AD.

Identification of a new functional domain of Nogo-A that promotes inflammatory pain and inhibits neurite growth through binding to NgR1.

Nogo-A is a key inhibitory molecule to axon regeneration, and plays diverse roles in other pathological conditions, such as stroke, schizophrenia, and neurodegenerative diseases. Nogo-66 and Nogo-Δ20 fragments are two known functional domains of Nogo-A, which act through the Nogo-66 receptor (NgR1) and sphingosine-1-phosphate receptor 2 (S1PR2), respectively. Here, we reported a new functional domain of Nogo-A, Nogo-A aa 846-861, was identified in the Nogo-A-specific segment that promotes complete Freund's adjuvant (CFA)-induced inflammatory pain. Intrathecal injection of its antagonist peptide 846-861PE or the specific antibody attenuated the CFA-induced inflammatory heat hyperalgesia. The 846-861 PE reduced the content of transient receptor potential vanilloid subfamily member 1 (TRPV1) in dorsal root ganglia (DRG) and decreased the response of DRG neurons to capsaicin. These effects were accompanied by a reduction in LIMK/cofilin phosphorylation and actin polymerization. GST pull-down and fluorescence resonance energy transfer (FRET) assays both showed that Nogo-A aa 846-861 bound to NgR1. Moreover, we demonstrated that Nogo-A aa 846-861 inhibited neurite outgrowth from cortical neurons and DRG explants. We concluded that Nogo-A aa 846-861 is a novel ligand of NgR1, which activates the downstream signaling pathways that inhibit axon growth and promote inflammatory pain.

A TRPV1 antagonist, PAC-14028 does not increase the risk of tumorigenesis in chemically induced mouse skin carcinogenesis

PAC-14028 (Asivatrep: C21H22F5N3O3S) cream is a novel, topical nonsteroidal, anti-inflammatory, and TRPV1 (transient receptor potential vanilloid subfamily, member 1) antagonist for the treatment of mild to moderate atopic dermatitis. Concerns about the risk of tumor development by TRPV1 blockade in the skin have been prompted, but these findings were proved to be indirect or are still controversial. This study was tested to determine whether TRPV1 selective antagonist, PAC-14028 cream is safe from the promotion of skin tumorigenesis in the two-stage carcinogenesis model. PAC-14028 cream, 0.25%, 0.5%, or 1.0% was applied once daily topically to mouse skin for up to 24 weeks in two-stage chemical carcinogenesis testing using 7, 12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA). Morbidity/death, clinical signs, tumor formation, activity of EGFR/Akt/mTOR signaling, and systemic exposure to PAC-14028 were investigated. Daily dermal administration of PAC-14028, was not skin carcinogenic. There was also no evidence on the activation of EGFR/Akt/mTOR signaling pathway by the topical treatment of PAC-14028. On Day 169, 1.0% (20 mg/kg/day) of PAC-14028 in female mice resulted in a Cmax and AUC0-τ of 12916.0 ng/mL and 78962.9 ng‧hr/mL, respectively. PAC-14028 cream was well tolerated and did not increase the risk of skin tumorigenesis in two-stage carcinogenesis study.

AAV-mediated siRNA against TRPV1 reduces nociception in a rat model of bone cancer pain

ABSTRACTObjective: Bone cancer pain is characterized by moderate to severe ongoing pain that commonly requires the use of opiates. Transient receptor potential vanilloid subfamily member 1 (TRPV1), a new target of the analgesics, activated by heat, protons and capsaicin and the hot component of pepper. However, little is known of the anti-nociceptive effects of TRPV1 in cancer-induced bone pain. RNA interference (RNAi) has proven to be a powerful technique to study the function of genes by producing knock-down phenotypes. The aim of this study is to investigate the potential role of TRPV1 in rat model of bone cancer pain.Methods: Bone cancer pain animal model was created by tumor cell implantation (TCI). An AAV-mediated siRNA against TRPV1 was intrathecally delivered into the rats. Animal behaviors were measured using a set of mechanical or electronic von Frey apparatus and hot plate. mRNA and protein expression were examined by using qPCR and western blot methods.Results: Mechanical threshold and paw withdrawal latency in response to thermal stimulation were significantly elevated in rats with intrathecal administration of AAV-mediated siRNA against TRPV1. Moreover, class I histone deacetylases (HDACs), which plays a critical role in the neuro-inflammation response, and TNFα in the spinal cord were also significantly suppressed upon knockdown of TRPV1 by AAV-mediated siRNA against TRPV1 in rat spinal cord.Conclusions: Knockdown of TRPV1 effectively ameliorated mechanical allodynia and thermal hyperalgesia induced by TCI. Our data demonstrated that modulate the expression of TRPV1 in the spinal cord could be a potential therapeutic approach for bone cancer pain.

Itch induces conditioned place aversion in mice

Itch sensation consists of both sensory and emotional components. The molecular and cellular mechanisms underlying the transduction and transmission of itch sensation have been studied extensively in rodents. However, whether itch induces emotional responses in mice still remains unknown. We found that pruritogens induced conditioned place aversion (CPA) in mice, and that the CPA lasted for at least two weeks. Disruption of itch signal transmission by depletion of peripheral sensory fibers expressing TRPV1 (transient receptor potential vanilloid subfamily, member 1) attenuated chloroquine-induced CPA. Consistently, ablation of itch-specific neurons that express gastrin-releasing peptide receptor in the spinal cord also abolished itch-induced CPA, confirming that itch-induced CPA is dependent on the spinal itch circuit. Thus, these results demonstrate that itch can induce CPA in mice, which requires peripheral itch signal inputs.

Do TRPV1 antagonists increase the risk for skin tumourigenesis? A collaborative in vitro and in vivo assessment.

A recent hypothesis suggesting that the pharmacological target TRPV1 (transient receptor potential vanilloid subfamily, member 1) may function as a tumour suppressor, which potentially impacts the development of TRPV1 antagonist therapeutics for a range of conditions. However, little is known about the long-term physiologic effects of TRPV1 blockade in the skin. In vitro and in vivo studies suggested that the potent TRPV1 competitive antagonist AMG-9810 promoted proliferation in N/TERT1 cells (telomerase-immortalised primary human keratinocytes 1) and tumour development in mouse skin that was mediated through EGFR/Akt/mTOR signalling. We attempted to reproduce the reported in vitro and in vivo findings to further explore this hypothesis to understand the underlying mechanism and the risk associated with TRPV1 antagonism in the skin. In vitro proliferation studies using multiple methods and topical application with AMG-9810 and structurally similar TRPV1 antagonists such as SB-705498 and PAC-14028 were performed. Although we confirmed expression of TRPV1 in primary human epidermal keratinocytes (HEKn) and spontaneously immortalised human keratinocytes (HaCaT), we were unable to demonstrate cell proliferation in either cell type or any clear evidence of increased expression of proteins in the EGFR/Akt/mTOR signalling pathway with these molecules. We were also unable to demonstrate skin tumour promotion or underlying molecular mechanisms involved in the EGFR/Akt/mTOR signalling pathway in a single-dose and two-stage carcinogenesis mouse study treated with TRPV1 antagonists. In conclusion, our data suggest that inhibiting the pharmacological function of TRPV1 in skin by specific antagonists has not been considered to be indicative of skin tumour development.

Direct Anandamide Activation of TRPV1 Produces Divergent Calcium and Current Responses

In the brainstem nucleus of the solitary tract (NTS), primary vagal afferent neurons express the transient receptor potential vanilloid subfamily member 1 (TRPV1) at their central terminals where it contributes to quantal forms of glutamate release. The endogenous membrane lipid anandamide (AEA) is a putative TRPV1 agonist in the brain, yet the extent to which AEA activation of TRPV1 has a neurophysiological consequence is not well established. We investigated the ability of AEA to activate TRPV1 in vagal afferent neurons in comparison to capsaicin (CAP). Using ratiometric calcium imaging and whole-cell patch clamp recordings we confirmed that AEA excitatory activity requires TRPV1, binds competitively at the CAP binding site, and has low relative affinity. While AEA-induced increases in peak cytosolic calcium were similar to CAP, AEA-induced membrane currents were significantly smaller. Removal of bath calcium increased the AEA current with no change in peak CAP currents revealing a calcium sensitive difference in specific ligand activation of TRPV1. Both CAP- and AEA-activated TRPV1 currents maintained identical reversal potentials, arguing against a major difference in ion selectivity to resolve the AEA differences in signaling. In contrast with CAP, AEA did not alter spontaneous glutamate release at NTS synapses. We conclude: (1) AEA activation of TRPV1 is markedly different from CAP and produces different magnitudes of calcium influx from whole-cell current; and (2) exogenous AEA does not alter spontaneous glutamate release onto NTS neurons. As such, AEA may convey modulatory changes to calcium-dependent processes, but does not directly facilitate glutamate release.

Inhibition of TNF reduces mechanical orofacial hyperalgesia induced by Complete Freund's Adjuvant by a TRPV1-dependent mechanism in mice.

Inflammation in the orofacial region results in pain and is associated with many pathological states, including migraine, neuralgias and temporomandibular disorder. Although extensively studied, the mechanisms responsible for these conditions are not known and effective treatments are lacking. We reported earlier that the proinflammatory cytokine tumor necrosis factor (TNF) plays an important role in regulation of trigeminal ganglion (TG) neuron function in vitro. In the present study we investigated the role of TNF in mechanical hypersensitivity in mice. We employed the Complete Freund's Adjuvant (CFA)-induced model of orofacial pain and evaluated the effect of blocking of soluble TNF activity by peripheral administration of the novel dominant negative TNF biologic, XPro1595. We show that CFA administration into the lower lip causes hyperalgesia and an increase in both expression of transient receptor potential vanilloid subfamily member 1 (TRPV1) mRNA and in the average intensity of TRPV1 protein immunoreactivity in TG neurons. We also show that intraperitoneal administration of XPro1595 prevents both CFA-induced mechanical hypersensitivity and, as shown in immunohistochemical staining - upregulation of TRPV1 protein expression in TG neurons. We conclude that one of the possible regulatory mechanisms of TNF in pain involves upregulation of the nociceptor TRPV1, and that peripheral treatment with a selective anti-soluble TNF biologic can prevent hyperalgesia caused by inflammation in the orofacial region. Therefore, these new findings suggest that XPro1595 may serve as a novel treatment for orofacial pain disorders.

Exploration of the Esophageal Mucosal Barrier in Non-Erosive Reflux Disease.

In the absence of visible mucosal damage, it is hypothesized that the esophageal mucosal barrier is functionally impaired in patients with non-erosive reflux disease (NERD). The aim of the present study was to perform an exploratory analysis of the mucosal barrier in NERD compared to erosive esophagitis (EE) and controls. A second aim was to explore TRPV1 gene transcription in relation to the mucosal barrier function and heartburn symptoms. In this prospective study, 10 NERD patients, 11 patients with active erosive esophagitis and 10 healthy volunteers were included. Biopsies from non-eroded mucosa were obtained for (1) ex vivo analyses (Ussing chamber) of transepithelial electrical resistance (TEER) and permeability (2) gene transcription of tight-junction proteins and transient receptor potential vanilloid subfamily member 1 (TRPV1). No differences in TEER or permeability were found between NERD and healthy volunteers, whereas TEER was lower in patients with erosive esophagitis. TRPV1 gene transcription was not significantly different between EE, NERD and controls. Conclusions: esophageal mucosal barrier function and TRPV1 transcription is not significantly altered in NERD patients. Future research is needed to explore other potential mechanisms that may account for the high symptom burden in these patients.

New Mechanism of Bone Cancer Pain: Tumor Tissue-Derived Endogenous Formaldehyde Induced Bone Cancer Pain via TRPV1 Activation.

In recent years, our serial investigations focused on the role of cancer cells-derived endogenous formaldehyde in bone cancer pain. We found that cancer cells produced formaldehyde through demethylation process by serine hydroxymethyltransferase (SHMT1 and SHMT2) and lysine-specific histone demethylase 1 (LSD1). When the cancer cells metastasized into bone marrow, the elevated endogenous formaldehyde induced bone cancer pain through activation on the transient receptor potential vanilloid subfamily member 1 (TRPV1) in the peripheral nerve fibers. More interestingly, TRPV1 expressions in the peripheral fibers were upregulated by the local insulin-like growth factor I (IGF-I) produced by the activated osteoblasts. In conclusion, tumor tissue-derived endogenous formaldehyde induced bone cancer pain via TRPV1 activation.

Inaugural Message from the Founding Editor-in-Chief.

Given the remarkable advances made over the last several decades in science and medicine, there could be no better and opportune time to launch the Journal of Translational Science (JTS). We have been fortunate to witness the integration of multiple areas of discovery in science and medicine to push the envelope for the diagnosis and treatment of disorders that can affect any region of the body. In developed countries such as the United States, life expectancy continues to increase and is accompanied by a one percent decrease in the age-adjusted death rate from the years 2000 through 2011. Yet, with the increasing growth and lifespan of the world's population, it is expected that the incidence of a number of disorders, such as metabolic disease, and neurodegenerative disorders, also will continue to grow. For example, the World Health Organization reports that diabetes mellitus will be ranked as the seventh leading cause of death by the year 2030. As a result, multiple novel therapeutic strategies are currently being advanced to treat disorders that currently have limited remedies. In particular, stem cell applications have quickly advanced and are being considered for numerous disorders that include cardiovascular disease, diabetes mellitus, cancer, inflammatory bowel disease, peripheral ischemia, graft versus host disease, and nervous system disorders. More than 40 years prior, the use of bone marrow transplantation set the stage for the treatment of hematological disorders and cancer with the use of stem cells. Presently, more than 50,000 bone marrow transplants are performed every year using autologous and allogeneic hematopoietic stem cells. In addition, unique cellular channels, such as the vanilloid (capsaicin) receptor TRPV1 (transient receptor potential, vanilloid subfamily member 1) and a member of the TRP superfamily of cation channels, are being pursued for a diverse spectrum of disorders that range from pain management to neuronal protection of the brain following stroke. Increasing consideration also is being directed to the field of microRNAs (miRNAs). MiRNAs consist of 19-25 nucleotides, are small non-coding ribonucleic acids (RNAs), and can control gene expression by silencing targeted messenger RNAs (mRNAs) translated by specific genes. With the explosion of new studies, miRNAs are reported to play critical roles in stem cell renewal, tissue repair, and potential disease progression in areas such as those of the cardiac, gastrointestinal, and nervous systems. Although these therapeutic strategies appear initially to be diverse, upon closer inspection each depends upon a “common signaling platform” that is intimately connected through cellular pathways that can significantly affect clinical outcome in patients. It is clear that cellular and genetic targets can easily impact multiple disease entities. The translation of these pathways into relevant clinical treatments can yield fruit for many disorders. JTS was conceived with this knowledge in mind. JTS is a novel open access journal that will focus upon the translation of cellular, molecular, and genetic pathways into clinical strategies for multiple medical disciplines that can impact a broad spectrum of disorders. These disorders can involve all aspects of translational research and medicine to include stem cells, degenerative diseases, aging, immune function, tumorigenesis, epigenetics, musculoskeletal function, cognition, behavior, metabolic function, and targets of the neuronal, cardiac, pulmonary, gastrointestinal, and vascular systems. JTS will provide a platform in today's scientific and medical literature to serve as an international forum for the healthcare and scientific communities worldwide to translate basic and clinical research studies into clinical therapies as well as report upon prognostics, novel therapeutic strategies, and biomarker development. JTS will offer multiple venues to present authors' thoughts and investigations as original research papers, review papers, clinical studies, editorials, expert opinion and perspective papers, commentaries, book reviews, and letters to the editor. Ultimately, JTS will promote a rigorous, fair, and constructive evaluation of all submitted articles. Papers will be processed in an extremely timely fashion so that all authors can follow the progress of the papers during the evaluation, copyediting, and publication phases. We are extremely excited with the launch of JTS and believe that the journal will fill a great void in the reporting of today's scientific and medical discoveries. JTS will serve as an international forum for the greatest degree of scholarship in the research and clinical communities worldwide to translate pioneering “bench to bedside” breakthroughs into successful clinical strategies. On behalf of the Editorial Team and the Editorial Board, welcome to JTS!

Acidic Extracellular Microenvironment in Myeloma-Colonized Bone Contributes to Bone Pain

Multiple myeloma (MM) bone disease results in devastating bone pain and fractures, which are the major cause of morbidity, and contribute to increased mortality and diminish the quality of life in MM patients. Current treatments for MM bone pain do not completely control the pain and have serious side effects. Thus, new therapies are needed to control myeloma bone pain. However, the mechanisms responsible for MM-associated bone pain are poorly understood. Specific osteoclast inhibitors (bisphosphonates and denosumab) can reduce bone pain in MM patients, suggesting that factors released at the tumor-bone interface during osteoclastic bone resorption may be important contributors to bone pain.Bone-resorbing osteoclasts release protons to dissolve bone minerals and aggressively proliferating tumor cells also release protons/lactate as a consequenece of aerobic glycolysis. Since acidosis is algogenic for primary afferent sensory neurons, we reasoned that an acidic extracellular microenvironment created by the release of protons by osteoclasts and MM cells play a critical role in the pathophysiology of bone pain.To investigate the mechanism of bone pain associated with MM, we used an animal model in which the JJN3 human MM cells were inoculated into the tibiae of SCID mice. Control mice received PBS. Bone pain was assessed by determining tactile hypersensitivity and thermal hyperalgesia of JJN3-bearing mice using von Frey and plantar tests.Administration of the pH probe acridine orange to JJN3-bearing mice revealed that resorption pits beneath bone-resorbing osteoclasts and JJN3-colonized tibiae are acidic. Mice bearing JJN3 MM in their tibiae displayed progressive tactile hypersensitivity and thermal hyperalgesia as the tumor grew. Of note, the bisphosphonate zoledronic acid significantly reduced the progression of the tactile hypersensitivity and thermal hyperalgesia, suggesting that these nociceptive behaviors of JJN3-bearing mice are due to osteoclast-mediated bone pain. Importantly, the non-selective proton pump inhibitor bafilomycin A1 inhibited the creation of the acidic extracellular microenvironment in JJN3-colonized bone and significantly prevented the progression of the nociceptive behaviors. These results support that the acidic extracellular microenvironment is responsible for evoking bone pain. Immunohistochemical examination to identify acid-sensing mechanisms present in bone showed that the calcitonin gene-related peptide (CGRP)-positive sensory neurons innervating bone are adjacent to osteoclasts with co-expression of the acid-sensing nociceptor, the transient receptor potential vanilloid subfamily member 1 (TRPV1). To determine the role of TRPV1 in the excitation of sensory neurons, primary sensory neuron cells isolated from dorsal root ganglion (DRG) were exposed to acidic medium (pH 6.5) and examined for intracellular Ca2+ mobilization using Fura 2 AM calcium imaging assays. Acidic medium induced Ca2+ influx in DRG sensory neuron cells and the induced Ca2+ influx was blocked in the presence of the specific TRPV1 antagonist SB366791, while the specific TRPV4 antagonist RN1734 showed no effect. Further, the specific antagonist for the acid-sensing ion channel 3 (ASIC3), APETx2, also blocked the induction of Ca2+ influx. Neutral medium (pH 7.4) did not induce Ca2+ influx. Taken together, these results suggest that TRPV1 and ASIC3 play an important role in the excitation of sensory neurons exposed to acidic extracellular microenvironment.Our results suggest that the acidic extracellular microenvironments created by protons released from osteoclasts and MM cells excite sensory neurons associated with bone via the acid-sensing nociceptors, TRPV1 and ASIC3, to evoke bone pain. TRPV1 and ASIC3 may be potential targets for ameliorating bone pain in MM. DisclosuresRoodman:Eli Lilly and Co.: Research Funding.

Blocking TRPV1 in nucleus accumbens inhibits persistent morphine conditioned place preference expression in rats.

The function of TRPV1 (transient receptor potential vanilloid subfamily, member 1) in the central nervous system is gradually elucidated. It has been recently proved to be expressed in nucleus accumbens (NAc), a region playing an essential role in mediating opioid craving and taking behaviors. Based on the general role of TRPV1 antagonist in blocking neural over-excitability by both pre- and post-synaptic mechanisms, TRPV1 antagonist capsazepine (CPZ) was tested for its ability to prohibit persistent opioid craving in rats. In the present study, we assessed the expression of TRPV1 in nucleus accumbens and investigated the effect of CPZ in bilateral nucleus accumbens on persistent morphine conditioned place preference (mCPP) in rats. We also evaluated the side-effect of CPZ on activity by comparing cross-beam times between groups. We found that morphine conditioned place preference increased the TRPV1 expression and CPZ attenuated morphine conditioned place preference in a dose-dependent and target–specific manner after both short- and long-term spontaneous withdrawal, reflected by the reduction of the increased time in morphine-paired side. CPZ (10 nM) could induce prolonged and stable inhibition of morphine conditioned place preference expression. More importantly, CPZ did not cause dysfunction of activity in the subjects tested, which indicates the inhibitory effect was not obtained at the sacrifice of regular movement. Collectively, these results indicated that injection of TRPV1 antagonist in nucleus accumbens is capable of attenuating persistent morphine conditioned place preference without affecting normal activity. Thus, TRPV1 antagonist is one of the promising therapeutic drugs for the treatment of opioid addiction.