FGF13 enhances the function of TRPV1 by stabilizing microtubules and regulates acute and chronic itch.

Itching is an aversive somatosensation that triggers the desire to scratch. Transient receptor potential (TRP) channel proteins are key players in acute and chronic itch. However, whether the modulatory effect of fibroblast growth factor 13 (FGF13) on acute and chronic itch is associated with TRP channel proteins is unclear. Here, we demonstrated that conditional knockout of Fgf13 in dorsal root ganglion neurons induced significant impairment in scratching behaviors in response to acute histamine-dependent and chronic dry skin itch models. Furthermore, FGF13 selectively regulated the function of the TRPV1, but not the TRPA1 channel on Ca2+ imaging and electrophysiological recordings, as demonstrated by a significant reduction in neuronal excitability and current density induced by TRPV1 channel activation, whereas TRPA1 channel activation had no effect. Changes in channel currents were also verified in HEK cell lines. Subsequently, we observed that selective modulation of TRPV1 by FGF13 required its microtubule-stabilizing effect. Furthermore, in FGF13 knockout mice, only the overexpression of FGF13 with a tubulin-binding domain could rescue TRP channel function and the impaired itch behavior. Our findings reveal a novel mechanism by which FGF13 is involved in TRPV1-dependent itch transduction and provide valuable clues for alleviating pathological itch syndrome.

Transient receptor potential vanilloid 1 involved in the analgesic effects of total flavonoids extracted from Longxuejie ().

OBJECTIVE: To evaluate the analgesic effects of total flavonoids of Longxuejie (Resina Dracaenae Cochinchinensis) (TFDB) and explore the possible analgesic mechanism associated with transient receptor potential vanilloid 1 (TRPV1). METHODS: Whole-cell patch clamp technique was used to observe the effects of TFDB on capsaicin-induced TRPV1 currents. Rat experiments in vivo were used to observe the analgesic effects of TFDB. Western blot and immunofluorescence experiments were used to test the change of TRPV1 expression in DRG neurons induced by TFDB. RESULTS: Results showed that TFDB inhibited capsaicin-induced TRPV1 receptor currents in acutely isolated dorsal root ganglion (DRG) neurons of rats and the half inhibitory concentration was (16.7 ± 1.6) mg/L. TFDB (2-20 mg/kg) showed analgesic activity in the phase Ⅱ of formalin test and (0.02-2 mg per paw) reduced capsaicin-induced licking times of rats. TFDB (20 mg/kg) was fully efficacious on complete Freund's adjuvant (CFA)-induced inflammatory thermal hyperalgesia and capsaicin could weaken the analgesic effects. The level of TRPV1 expressions of DRG neurons was also decreased in TFDB-treated CFA-inflammatory pain rats. CONCLUSION: All these results indicated that the analgesic effect of TFDB may contribute to their modulations on both function and expression of TRPV1 channels in DRG neurons.

Low-Intensity Extracorporeal Shock Wave Therapy Ameliorates Detrusor Hyperactivity with Impaired Contractility via Transient Potential Vanilloid Channels: A Rat Model for Ovarian Hormone Deficiency.

This study explores low-intensity extracorporeal shock wave therapy (LiESWT)'s efficacy in alleviating detrusor hyperactivity with impaired contractility (DHIC) induced by ovarian hormone deficiency (OHD) in ovariectomized rats. The rats were categorized into the following four groups: sham group; OVX group, subjected to bilateral ovariectomy (OVX) for 12 months to induce OHD; OVX + SW4 group, underwent OHD for 12 months followed by 4 weeks of weekly LiESWT; and OVX + SW8 group, underwent OHD for 12 months followed by 8 weeks of weekly LiESWT. Cystometrogram studies and voiding behavior tracing were used to identify the symptoms of DHIC. Muscle strip contractility was evaluated through electrical-field, carbachol, ATP, and KCl stimulations. Western blot and immunofluorescence analyses were performed to assess the expressions of various markers related to bladder dysfunction. The OVX rats exhibited significant bladder deterioration and overactivity, alleviated by LiESWT. LiESWT modified transient receptor potential vanilloid (TRPV) channel expression, regulating calcium concentration and enhancing bladder capacity. It also elevated endoplasmic reticulum (ER) stress proteins, influencing ER-related Ca2+ channels and receptors to modulate detrusor muscle contractility. OHD after 12 months led to neuronal degeneration and reduced TRPV1 and TRPV4 channel activation. LiESWT demonstrated potential in enhancing angiogenic remodeling, neurogenesis, and receptor response, ameliorating DHIC via TRPV channels and cellular signaling in the OHD-induced DHIC rat model.

Calcitonin gene­related peptide alleviates hyperoxia­induced human alveolar cell injury via the CGRPR/TRPV1/Ca2+ axis.

Although exogenous calcitonin gene­related peptide (CGRP) protects against hyperoxia­induced lung injury (HILI), the underlying mechanisms remain unclear. The present study attempted to elucidate the molecular mechanism by which CGRP protects against hyperoxia­induced alveolar cell injury. Human alveolar A549 cells were treated with 95% hyperoxia to establish a hyperoxic cell injury model. ELISA was performed to detect the CGRP secretion. Immunofluorescence, quantitative (q)PCR, and western blotting were used to detect the expression and localization of CGRP receptor (CGRPR) and transient receptor potential vanilloid 1 (TRPV1). Cell counting kit­8 and flow cytometry were used to examine the proliferation and apoptosis of treated cells. Digital calcium imaging and patch clamp were used to analyze the changes in intracellular Ca2+ signaling and membrane currents induced by CGRP in A549 cells. The mRNA and protein expression levels of Cyclin D1, proliferating cell nuclear antigen (PCNA), Bcl­2 and Bax were detected by qPCR and western blotting. The expression levels of CGRPR and TRPV1 in A549 cells were significantly downregulated by hyperoxic treatment, but there was no significant difference in CGRP release between cells cultured under normal air and hyperoxic conditions. CGRP promoted cell proliferation and inhibited apoptosis in hyperoxia, but selective inhibitors of CGRPR and TRPV1 channels could effectively attenuate these effects; TRPV1 knockdown also attenuated this effect. CGRP induced Ca2+ entry via the TRPV1 channels and enhanced the membrane non­selective currents through TRPV1 channels. The CGRP­induced increase in intracellular Ca2+ was reduced by inhibiting the phospholipase C (PLC)/protein kinase C (PKC) pathway. Moreover, PLC and PKC inhibitors attenuated the effects of CGRP in promoting cell proliferation and inhibiting apoptosis. In conclusion, exogenous CGRP acted by inversely regulating the function of TRPV1 channels in alveolar cells. Importantly, CGRP protected alveolar cells from hyperoxia­induced injury via the CGRPR/TRPV1/Ca2+ axis, which may be a potential target for the prevention and treatment of the HILI.

Correlation of TRPA1 RNAscope and Agonist Responses.

The TRPA1 ion channel is a sensitive detector of reactive chemicals, found primarily on sensory neurons. The phenotype exhibited by mice lacking TRPA1 suggests its potential as a target for pharmacological intervention. Antibody-based detection for distribution analysis is a standard technique. In the case of TRPA1, however, there is no antibody with a plausible validation in knockout animals or functional studies, but many that have failed in this regard. To this end we employed the single molecule in situ hybridization technique RNAscope on sensory neurons immediately after detection of calcium responses to the TRPA1 agonist allyl isothiocyanate. There is a clearly positive correlation between TRPA1 calcium imaging and RNAscope detection (R = 0.43), although less than what might have been expected. Thus, the technique of choice should be carefully considered to suit the research question. The marginal correlation between TRPV1 RNAscope and the specific agonist capsaicin indicates that such validation is advisable for every RNAscope target. Given the recent description of a long-awaited TRPA1 reporter mouse, TRPA1 RNAscope detection might still have its use cases, for detection of RNA at particular sites, for example, defined structurally or by other molecular markers.

Exploration and structure-activity relationship research of benzenesulfonamide derivatives as potent TRPV4 inhibitors for treating acute lung injury.

RN-9893, a TRPV4 antagonist identified by Renovis Inc., showcased notable inhibition of TRPV4 channels. This research involved synthesizing and evaluating three series of RN-9893 analogues for their TRPV4 inhibitory efficacy. Notably, compounds 1b and 1f displayed a 2.9 to 4.5-fold increase in inhibitory potency against TRPV4 (IC50 = 0.71 ± 0.21 µM and 0.46 ± 0.08 µM, respectively) in vitro, in comparison to RN-9893 (IC50 = 2.07 ± 0.90 µM). Both compounds also significantly outperformed RN-9893 in TRPV4 current inhibition rates (87.6 % and 83.2 % at 10 µM, against RN-9893's 49.4 %). For the first time, these RN-9893 analogues were profiled in an in vivo mouse model, where intraperitoneal injections of 1b or 1f at 10 mg/kg notably mitigated symptoms of acute lung injury induced by lipopolysaccharide (LPS). These outcomes indicate that compounds 1b and 1f are promising candidates for acute lung injury treatment.

Elucidation of the Role of TRPV1, VEGF-A, TXA2, Redox Homeostasis, and Inflammatory Cascades in Protection against Cold Injuries by Herbosomal-Loaded PEG-Poloxamer Topical Formulation.

High-altitude regions, cold deserts, permafrost regions, and the polar region have some of the severest cold conditions on earth and pose immense perils of cold injuries to exposed individuals. Accidental and unintended exposures to severe cold, either unintentionally or due to occupational risks, can greatly increase the risk of serious conditions including hypothermia, trench foot, and cold injuries like frostbite. Cold-induced vasoconstriction and intracellular/intravascular ice crystal formation lead to hypoxic conditions at the cellular level. The condition is exacerbated in individuals having inadequate and proper covering and layering, particularly when large area of the body are exposed to extremely cold environments. There is a paucity of preventive and therapeutic pharmacological modalities that have been explored for managing and treating cold injuries. Given this, an efficient modality that can potentiate the healing of frostbite was investigated by studying various complex pathophysiological changes that occur during severe cold injuries. In the current research, we report the effectiveness and healing properties of a standardized formulation, i.e., a herbosomal-loaded PEG-poloxamer topical formulation (n-HPTF), on frostbite. The intricate mechanistic pathways modulated by the novel formulation have been elucidated by studying the pathophysiological sequelae that occur following severe cold exposures leading to frostbite. The results indicate that n-HPTF ameliorates the outcome of frostbite, as it activates positive sensory nerves widely distributed in the epidermis transient receptor potential vanilloid 1 (TRPV1), significantly (p < 0.05) upregulates cytokeratin-14, promotes angiogenesis (VEGF-A), prominently represses the expression of thromboxane formation (TXA2), and significantly (p < 0.05) restores levels of enzymatic (glutathione reductase, superoxide dismutase, and catalase) and nonenzymatic antioxidants (glutathione). Additionally, n-HPTF attenuates oxidative stress and the expression of inflammatory proteins PGF-2α, NFκB-p65, TNF-α, IL-6, IL-1ß, malondialdehyde (MDA), advanced oxidative protein products (AOPP), and protein carbonylation (PCO). Masson's Trichrome staining showed that n-HPTF stimulates cellular proliferation, and increases collagen fiber deposition, which significantly (p < 0.05) promotes the healing of frostbitten tissue, as compared to control. We conclude that protection against severe cold injuries by n-HPTF is mediated via modulation of pathways involving TRPV1, VEGF-A, TXA2, redox homeostasis, and inflammatory cascades. The study is likely to have widespread implications for the prophylaxis and management of moderate-to-severe frostbite conditions.

Esketamine alleviates hypoxia/reoxygenation injury of cardiomyocytes by regulating TRPV1 expression and inhibiting intracellular Ca2+ concentration.

OBJECTIVE: This study aimed to investigate the effect of Esketamine (ESK) on the Hypoxia/Reoxygenation (H/R) injury of cardiomyocytes by regulating TRPV1 and inhibiting the concentration of intracellular Ca2+. METHODS: The H/R injury model of H9c2 cardiomyocytes was established after 4h hypoxia and 6h reoxygenation. H9c2 cells were treated with different concentrations of ESK or TRPV1 agonist capsaicin (10 µM) or TRPV1 inhibitor capsazepine (1 µM). Cell viability was detected by CCK-8 method, and apoptosis by flow cytometry. Intracellular Ca2+ concentration was evaluated by Fluo-4 AM. LDH, MDA, SOD, and GSH-Px were detected with corresponding commercial kits. TRPV1 and p-TRPV1 proteins were detected by Western blot. RESULTS: After H/R, H9c2 cell viability decreased, apoptosis increased, intracellular Ca2+ concentration increased, LDH and MDA levels increased, SOD and GSH-Px levels decreased, and p-TRPV1 expression increased. ESK treatment rescued these changes induced by H/R. After up-regulating TRPV1, the protective effect of ESK on H/R injury of H9c2 cells was weakened, while down-regulating TRPV1 could further protect against H/R injury. CONCLUSION: ESK alleviates H/R injury of cardiomyocytes by regulating TRPV1 expression and inhibiting intracellular Ca2+ concentration.

The ion channel TRPV5 regulates B-cell signaling and activation.

Introduction: B-cell activation triggers the release of endoplasmic reticulum calcium stores through the store-operated calcium entry (SOCE) pathway resulting in calcium influx by calcium release-activated calcium (CRAC) channels on the plasma membrane. B-cell-specific murine knockouts of SOCE do not impact humoral immunity suggesting that alternative channels may be important. Methods: We identified a member of the calcium-permeable transient receptor potential (TRP) ion channel family, TRPV5, as a candidate channel expressed in B cells by a quantitative polymerase chain reaction (qPCR) screen. To further investigate the role of TRPV5 in B-cell responses, we generated a murine TRPV5 knockout (KO) by CRISPR-Cas9. Results: We found TRPV5 polarized to B-cell receptor (BCR) clusters upon stimulation in a PI3K-RhoA-dependent manner. TRPV5 KO mice have normal B-cell development and mature B-cell numbers. Surprisingly, calcium influx upon BCR stimulation in primary TRPV5 KO B cells was not impaired; however, differential expression of other calcium-regulating proteins, such as ORAI1, may contribute to a compensatory mechanism for calcium signaling in these cells. We demonstrate that TRPV5 KO B cells have impaired spreading and contraction in response to membrane-bound antigen. Consistent with this, TRPV5 KO B cells have reduced BCR signaling measured through phospho-tyrosine residues. Lastly, we also found that TRPV5 is important for early T-dependent antigen specific responses post-immunization. Discussion: Thus, our findings identify a role for TRPV5 in BCR signaling and B-cell activation.

TRPV3 activation by different agonists accompanied by lipid dissociation from the vanilloid site.

TRPV3 represents both temperature- and ligand-activated transient receptor potential (TRP) channel. Physiologically relevant opening of TRPV3 channels by heat has been captured structurally, while opening by agonists has only been observed in structures of mutant channels. Here, we present cryo-EM structures that illuminate opening and inactivation of wild-type human TRPV3 in response to binding of two types of agonists: either the natural cannabinoid tetrahydrocannabivarin (THCV) or synthetic agonist 2-aminoethoxydiphenylborane (2-APB). We found that THCV binds to the vanilloid site, while 2-APB binds to the S1-S4 base and ARD-TMD linker sites. Despite binding to distally located sites, both agonists induce similar pore opening and cause dissociation of a lipid that occupies the vanilloid site in their absence. Our results uncover different but converging allosteric pathways through which small-molecule agonists activate TRPV3 and provide a framework for drug design and understanding the role of lipids in ion channel function.

TRPV4 promotes HBV replication and capsid assembly via methylation modification of H3K4 and HBc ubiquitin.

Hepatitis B virus (HBV) infection poses a significant burden on global public health. Unfortunately, current treatments cannot fully alleviate this burden as they have limited effect on the transcriptional activity of the tenacious covalently closed circular DNA (cccDNA) responsible for viral persistence. Consequently, the HBV life cycle should be further investigated to develop new anti-HBV pharmaceutical targets. Our previous study discovered that the host gene TMEM203 hinders HBV replication by participating in calcium ion regulation. The involvement of intracellular calcium in HBV replication has also been confirmed. In this study, we found that transient receptor potential vanilloid 4 (TRPV4) notably enhances HBV reproduction by investigating the effects of several calcium ion-related molecules on HBV replication. The in-depth study showed that TRPV4 promotes hepatitis B core/capsid protein (HBc) protein stability through the ubiquitination pathway and then promotes the nucleocapsid assembly. HBc binds to cccDNA and reduces the nucleosome spacing of the cccDNA-histones complex, which may regulate HBV transcription by altering the nucleosome arrangement of the HBV genome. Moreover, our results showed that TRPV4 promotes cccDNA-dependent transcription by accelerating the methylation modification of H3K4. In conclusion, TRPV4 could interact with HBV core protein and regulate HBV during transcription and replication. These data suggest that TRPV4 exerts multifaceted HBV-related synergistic factors and may serve as a therapeutic target for CHB.

Impact of TRP Channels on Extracellular Matrix Remodeling: Focus on TRPV4 and Collagen.

Disturbed remodeling of the extracellular matrix (ECM) is frequently observed in several high-prevalence pathologies that include fibrotic diseases of organs such as the heart, lung, periodontium, liver, and the stiffening of the ECM surrounding invasive cancers. In many of these lesions, matrix remodeling mediated by fibroblasts is dysregulated, in part by alterations to the regulatory and effector systems that synthesize and degrade collagen, and by alterations to the functions of the integrin-based adhesions that normally mediate mechanical remodeling of collagen fibrils. Cell-matrix adhesions containing collagen-binding integrins are enriched with regulatory and effector systems that initiate localized remodeling of pericellular collagen fibrils to maintain ECM homeostasis. A large cadre of regulatory molecules is enriched in cell-matrix adhesions that affect ECM remodeling through synthesis, degradation, and contraction of collagen fibrils. One of these regulatory molecules is Transient Receptor Potential Vanilloid-type 4 (TRPV4), a mechanically sensitive, Ca2+-permeable plasma membrane channel that regulates collagen remodeling. The gating of Ca2+ across the plasma membrane by TRPV4 and the consequent generation of intracellular Ca2+ signals affect several processes that determine the structural and mechanical properties of collagen-rich ECM. These processes include the synthesis of new collagen fibrils, tractional remodeling by contractile forces, and collagenolysis. While the specific mechanisms by which TRPV4 contributes to matrix remodeling are not well-defined, it is known that TRPV4 is activated by mechanical forces transmitted through collagen adhesion receptors. Here, we consider how TRPV4 expression and function contribute to physiological and pathological collagen remodeling and are associated with collagen adhesions. Over the long-term, an improved understanding of how TRPV4 regulates collagen remodeling could pave the way for new approaches to manage fibrotic lesions.

Advances in TRPV6 inhibitors for tumors by targeted therapies: Macromolecular proteins, synthetic small molecule compounds, and natural compounds.

TRPV6, a Ca2+-selective member of the transient receptor potential vanilloid (TRPV) family, plays a key role in extracellular calcium transport, calcium ion reuptake, and maintenance of a local low calcium environment. An increasing number of studies have shown that TRPV6 is involved in the regulation of various diseases. Notably, overexpression of TRPV6 is closely related to the occurrence of various cancers. Research confirmed that knocking down TRPV6 could effectively reduce the proliferation and invasiveness of tumors by mainly mediating the calcium signaling pathway. Hence, TRPV6 has become a promising new drug target for numerous tumor treatments. However, the development of TRPV6 inhibitors is still in the early stage, and the existing TRPV6 inhibitors have poor selectivity and off-target effects. In this review, we focus on summarizing and describing the structure characters, and mechanisms of existing TRPV6 inhibitors to provide new ideas and directions for the development of novel TRPV6 inhibitors.

Transient Receptor Potential Channels in the Healthy and Diseased Blood-Brain Barrier.

The large family of transient receptor potential (TRP) channels are integral membrane proteins that function as environmental sensors and act as ion channels after activation by mechanical (touch), physical (heat, pain), and chemical stimuli (pungent compounds such as capsaicin). Most TRP channels are localized in the plasma membrane of cells but some of them are localized in membranes of organelles and function as intracellular Ca2+-ion channels. TRP channels are involved in neurological disorders but their precise role(s) and relevance in these disorders are not clear. Endothelial cells of the blood-brain barrier (BBB) express TRP channels such as TRP vanilloid 1-4 and are involved in thermal detection by regulating BBB permeability. In neurological disorders, TRP channels in the BBB are responsible for edema formation in the brain. Therefore, drug design to modulate locally activity of TRP channels in the BBB is a hot topic. Today, the application of TRP channel antagonists against neurological disorders is still limited.

Discovery of N-(1,4-Benzoxazin-3-one) urea analogs as Mode-Selective TRPV1 antagonists.

A series of 1,4-benzoxazin-3-one analogs were investigated to discover mode-selective TRPV1 antagonists, since such antagonists are predicted to minimize target-based adverse effects. Using the high-affinity antagonist 2 as the lead structure, the structure activity relationship was studied by modifying the A-region through incorporation of a polar side chain on the benzoxazine and then by changing the C-region with a variety of substituted pyridine, pyrazole and thiazole moieties. The t-butyl pyrazole and thiazole C-region analogs provided high potency as well as mode-selectivity. Among them, antagonist 36 displayed potent and capsaicin-selective antagonism with IC50 = 2.31 nM for blocking capsaicin activation and only 47.5 % inhibition at 3 µM concentration toward proton activation, indicating that more than a 1000-fold higher concentration of 36 was required to inhibit proton activation than was required to inhibit capsaicin activation. The molecular modeling study of 36 with our homology model indicated that two π-π interactions with the Tyr511 and Phe591 residues by the A- and C-region and hydrogen bonding with the Thr550 residue by the B-region were critical for maintaining balanced and stable binding. Systemic optimization of antagonist 2, which has high-affinity but full antagonism for activators of all modes, led to the mode-selective antagonist 36 which represents a promising step in the development of clinical TRPV1 antagonists minimizing side effects such as hyperthermia and impaired heat sensation.

Effect of TRPV4 Antagonist GSK2798745 on Chlorine Gas-Induced Acute Lung Injury in a Swine Model.

As a regulator of alveolo-capillary barrier integrity, Transient Receptor Potential Vanilloid 4 (TRPV4) antagonism represents a promising strategy for reducing pulmonary edema secondary to chemical inhalation. In an experimental model of acute lung injury induced by exposure of anesthetized swine to chlorine gas by mechanical ventilation, the dose-dependent effects of TRPV4 inhibitor GSK2798745 were evaluated. Pulmonary function and oxygenation were measured hourly; airway responsiveness, wet-to-dry lung weight ratios, airway inflammation, and histopathology were assessed 24 h post-exposure. Exposure to 240 parts per million (ppm) chlorine gas for ≥50 min resulted in acute lung injury characterized by sustained changes in the ratio of partial pressure of oxygen in arterial blood to the fraction of inspiratory oxygen concentration (PaO2/FiO2), oxygenation index, peak inspiratory pressure, dynamic lung compliance, and respiratory system resistance over 24 h. Chlorine exposure also heightened airway response to methacholine and increased wet-to-dry lung weight ratios at 24 h. Following 55-min chlorine gas exposure, GSK2798745 marginally improved PaO2/FiO2, but did not impact lung function, airway responsiveness, wet-to-dry lung weight ratios, airway inflammation, or histopathology. In summary, in this swine model of chlorine gas-induced acute lung injury, GSK2798745 did not demonstrate a clinically relevant improvement of key disease endpoints.

Ca2+ Overload Decreased Cellular Viability in Magnetic Hyperthermia without a Macroscopic Temperature Rise.

Magnetic hyperthermia is a crucial medical engineering technique for treating diseases, which usually uses alternating magnetic fields (AMF) to interplay with magnetic substances to generate heat. Recently, it has been found that in some cases, there is no detectable temperature increment after applying an AMF, which caused corresponding effects surprisingly. The mechanisms involved in this phenomenon are not yet fully understood. In this study, we aimed to explore the role of Ca2+ overload in the magnetic hyperthermia effect without a perceptible temperature rise. A cellular system expressing the fusion proteins TRPV1 and ferritin was prepared. The application of an AMF (518 kHz, 16 kA/m) could induce the fusion protein to release a large amount of iron ions, which then participates in the production of massive reactive oxygen radicals (ROS). Both ROS and its induced lipid oxidation enticed the opening of ion channels, causing intracellular Ca2+ overload, which further led to decreased cellular viability. Taken together, Ca2+ overload triggered by elevated ROS and the induced oxidation of lipids contributes to the magnetic hyperthermia effect without a perceptible temperature rise. These findings would be beneficial for expanding the application of temperature-free magnetic hyperthermia, such as in cellular and neural regulation, design of new cancer treatment methods.

TRPV2 modulates mechanically Induced ATP Release from Human bronchial epithelial cells.

Repetitive bouts of coughing expose the large airways to significant cycles of shear stress. This leads to the release of alarmins and the tussive agent adenosine triphosphate (ATP) which may be modulated by the activity of ion channels present in the human airway. This study aimed to investigate the role of the transient receptor potential subfamily vanilloid member 2 (TRPV2) channel in mechanically induced ATP release from primary bronchial epithelial cells (PBECs).PBECs were obtained from individuals undergoing bronchoscopy. They were cultured in vitro and exposed to mechanical stress in the form of compressive and fluid shear stress (CFSS) or fluid shear stress (FSS) alone at various intensities. ATP release was measured using a luciferin-luciferase assay. Functional TRPV2 protein expression in human PBECs was investigated by confocal calcium imaging. The role of TRPV2 inhibition on FSS-induced ATP release was investigated using the TRPV2 inhibitor tranilast or siRNA knockdown of TRPV2. TRPV2 protein expression in human lung tissue was also determined by immunohistochemistry.ATP release was significantly increased in PBECs subjected to CFSS compared with control (unstimulated) PBECs (N = 3, ***P < 0.001). PBECs expressed functional TRPV2 channels. TRPV2 protein was also detected in fixed human lung tissue. ATP release from FFS stimulated PBECs was decreased by the TRPV2 inhibitor tranilast (N = 3, **P < 0.01) (vehicle: 159 ± 17.49 nM, tranilast: 25.08 ± 5.1 nM) or by TRPV2 siRNA knockdown (N = 3, *P < 0.05) (vehicle: 197 ± 24.52 nM, siRNA: 119 ± 26.85 nM).In conclusion, TRPV2 is expressed in the human airway and modulates ATP release from mechanically stimulated PBECs.

Voluntary wheel exercise improves glymphatic clearance and ameliorates colitis-associated cognitive impairment in aged mice by inhibiting TRPV4-induced astrocytic calcium activity.

BACKGROUND AND OBJECTIVES: Chronic colitis exacerbates neuroinflammation, contributing to cognitive impairment during aging, but the mechanism remains unclear. The polarity distribution of astrocytic aquaporin 4 (AQP4) is crucial for the glymphatic system, which is responsible for metabolite clearance in the brain. Physical exercise (PE) improves cognition in the aged. This study aims to investigate the protective mechanism of exercise in colitis-associated cognitive impairment. METHODS: To establish a chronic colitis model, 18-month-old C57BL/6 J female mice received periodic oral administration of 1% wt/vol dextran sodium sulfate (DSS) in drinking water. The mice in the exercise group received four weeks of voluntary wheel exercise. High-throughput sequencing was conducted to screen for differentially expressed genes. Two-photon imaging was performed to investigate the function of the astrocytic calcium activity and in vivo intervention with TRPV4 inhibitor HC-067047. Further, GSK1016790A (GSK1), a TRPV4 agonist, was daily intraperitoneally injected during the exercise period to study the involvement of TRPV4 in PE protection. Colitis pathology was confirmed by histopathology. The novel object recognition (NOR) test, Morris water maze test (MWM), and open field test were performed to measure colitis-induced cognition and anxiety-like behavior. In vivo two-photon imaging and ex vivo imaging of fluorescent CSF tracers to evaluate the function of the glymphatic system. Immunofluorescence staining was used to detect the Aß deposition, polarity distribution of astrocytic AQP4, and astrocytic phenotype. Serum and brain levels of the inflammatory cytokines were tested by Enzyme-linked immunosorbent assay (ELISA). The brain TUNEL assay was used to assess DNA damage. Expression of critical molecules was detected using Western blotting. RESULTS: Voluntary exercise alleviates cognitive impairment and anxiety-like behavior in aged mice with chronic colitis, providing neuroprotection against neuronal damage and apoptosis. Additionally, voluntary exercise promotes the brain clearance of Aß via increased glymphatic clearance. Mechanistically, exercise-induced beneficial effects may be attributed, in part, to the inhibition of TRPV4 expression and TRPV4-related calcium hyperactivity, subsequent promotion of AQP4 polarization, and modulation of astrocyte phenotype. CONCLUSION: The present study reveals a novel role of voluntary exercise in alleviating colitis-related cognitive impairment and anxiety disorder, which is mediated by the promotion of AQP4 polarization and glymphatic clearance of Aß via inhibition of TRPV4-induced astrocytic calcium hyperactivity.

TRPV3 promotes sebocyte inflammation via transcriptional modulating TLR2 in acne.

Acne is a common chronic inflammatory disease of the pilosebaceous unit. Transient receptor potential vanilloid 3 (TRPV3) is an ion channel that is involved in inflammatory dermatosis development. However, the involvement of TRPV3 in acne-related inflammation remains unclear. Here, we used acne-like mice and human sebocytes to examine the role of TRPV3 in the development of acne. We found that TRPV3 expression increased in the skin lesions of Propionibacterium acnes (P. acnes)-injected acne-like mice and the facial sebaceous glands (SGs) of acne patients. TRPV3 promoted inflammatory cytokines and chemokines secretion in human sebocytes and led to neutrophil infiltration surrounding the SGs in acne lesions, further exacerbating sebaceous inflammation and participating in acne development. Mechanistically, TRPV3 enhanced TLR2 level by promoting transcriptional factor phosphorylated-FOS-like antigen-1 (p-FOSL1) expression and its binding to the TLR2 promoter, leading to TLR2 upregulation and downstream NF-κB signaling activation. Genetic or pharmacological inhibition of TRPV3 both alleviated acne-like skin inflammation in mice via the TLR2-NF-κB axis. Thus, our study revealed the critical role of TRPV3 in sebaceous inflammation and indicated its potential as an acne therapeutic target.