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Brain temperature is strictly regulated by various endogenous mechanisms and significantly contributes to brain function in homeothermic animals, making it an important factor for health. Thermosensitive transient receptor potential (TRP) channels convert temperature information into electrical signals through cation influx. In particular, TRPV4 is involved in the regulation of brain function. TRPV4, constitutively active in neurons through its activation by brain temperature, increases neuronal firing. TRPV4KO mice have electroencephalogram abnormalities, resulting in depression-like and social behavioral abnormalities. This basic function of TRPV4, as a translator of brain temperature information, has been implicated in several diseases, including epilepsy and stress-induced depression. In addition to its neuronal functions, TRPV4 has many key functions in glia and vasculature that depend on brain temperature and contribute to brain activity. In this review, I summarize the importance of TRPV4 activities in relation to brain temperature and focus on how hyperthermia-induced TRPV4 dysfunction exacerbates brain diseases., Competing Interests: Declarations. Competing interest: The author declares that he has no competing interests., (© 2024. The Author(s).)

Attraction and mating between male and female animals depend on effective communication between conspecifics. However, in mosquitoes, we have only a rudimentary understanding of the sensory cues and receptors critical for the communication that is essential for reproductive behavior. While it is known that male Aedes aegypti use sound to help them identify females, it is not unclear whether sound detection is absolutely required since other cues such as vision may also participate in mating behavior. To determine the effect of eliminating hearing on mating success, we knocked out the Ae. aegypti TRPVa channel, which is a protein expressed in chordotonal neurons in the Johnston's organ (JO) that respond to sound-induced movements in the antenna. Loss of trpVa eradicated sound-induced responses from the JO, thereby abolishing hearing. Strikingly, mutation of trpVa eliminated mating behavior in males. In contrast, trpVa -null females mated, although this behavior was slightly delayed relative to wild-type females. Males and females produce sounds as they beat their wings at distinct frequencies during flight. Sound mimicking the female wingbeat induced flight, attraction, and copulatory-like behavior in wild-type males without females present, but not in trpVa -null males. Males are known to modulate their wingbeat frequencies before mating in the air, which is a phenomenon referred to as rapid frequency modulation (RFM). We found that RFM was absent in mosquitoes lacking TRPVa. We conclude that the requirement for trpVa and hearing for male reproductive behavior in Aedes is absolute, as mating in the deaf males is eliminated., Competing Interests: Competing interests statement:The authors declare no competing interest.

Assessing localization of the transient receptor potential vanilloid-1 (TRPV1) in skin nerve fibers is crucial for understanding its role in peripheral neuropathy and pain. However, information on the specificity and sensitivity of TRPV1 antibodies used for immunofluorescence (IF) on human skin is currently lacking. To find a reliable TRPV1 antibody and IF protocol, we explored antibody candidates from different manufacturers, used rat DRG sections and human skin samples for screening and human TRPV1-expressing HEK293 cells for further validation. Final specificity assessment was done on human skin samples. Additionally, we developed two automated image analysis methods: a Python-based deep-learning approach and a Fiji-based machine-learning approach. These methods involve training a model or classifier for nerve fibers based on pre-annotations and utilize a nerve fiber mask to filter and count TRPV1 immunoreactive puncta and TRPV1 fluorescence intensity on nerve fibers. Both automated analysis methods effectively distinguished TRPV1 signals on nerve fibers from those in keratinocytes, demonstrating high reliability as evidenced by excellent intraclass correlation coefficient (ICC) values exceeding 0.75. This method holds the potential to uncover alterations in TRPV1 associated with neuropathic pain conditions, using a minimally invasive approach., Competing Interests: Declarations Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

TRPV1, a polymodal and nonselective cation channel has unique gating mechanisms which is regulated by supramolecular complexes at the plasma membrane formed with membrane proteins, lipids and kinase pathways. Crosstalk between microtubule cytoskeleton with TRPV1 at various level has been established. Previously we demonstrated that the positively-charged residues present at specific tubulin-binding stretch sequences (i.e. TBS1 and TBS2, AA 710-730 and 770-797 respectively) located at the C-terminus of TRPV1 are crucial for tubulin interaction and such sequences have evolutionary origin. The nature of TRPV1-tubulin complex and its functional importance remain poorly understood. Here, we made several mutations in the TBS1 and TBS2 regions and characterized such mutants. Though these mutations reduce tubulin interaction drastically, a low and basal-level of tubulin interaction remains with these mutants. Substitution of positively-charged residues (Lys and Arg) to Ala in the TBS1, but not in TBS2 region results in reduced ligand-sensitivity. Such ligand-sensitivity is altered in response to Taxol or Nocodazole. We suggest that tubulin interaction at the TBS1 region favours channel opening while interaction in TBS2 favours channel closure. We demonstrate for the first time the functional significance of TRPV1-tubulin complex and endorse microtubule dynamics as a parameter that can alter TRPV1 channel functions. These findings can be relevant for several physiological functions and also in the context of chemotherapy-induced neuropathic pain caused by various microtubule stabilizing chemotherapeutic drugs. Thus, this characterization may indicate TRPV1 as a potential therapeutic target relevant for chemotherapeutic drug-induced peripheral neuropathies, neurodegeneration and other neurological disorders., Competing Interests: Declaration of competing interest All authors declare the existence of no conflict with this work. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Ethnopharmacological Relevance: Paeonol (PAE) and glycyrrhizic acid (GLY) are predominate components of 14 blood-entering ones of Piantongtang No. 1, which is a traditional Chinese medicine prescription for chronic migraine with minimal side effects. Both paeonol and glycyrrhizic acid exhibit analgesic, neuroprotective and anti-inflammatory properties individually. Our previous research has highlighted their combined effect (PAE + GLY) in ameliorating migraine symptoms. However, there are not yet any studies exploring the mechanism of action of PAE + GLY in the treatment of migraine., Aim of the Study: This research aimed to determine the mechanism of PAE + GLY in ameliorating the recurrent nitroglycerin-induced migraine-like phenotype in rats., Materials and Methods: Using a nitroglycerin-induced migraine model via subcutaneous injection in the neck, we evaluated the effect of PAE + GLY on migraine-like symptoms. Behavioural tests and biomarkers analysis were employed, alongside transcriptome sequencing (RNA-seq). Mechanistic insights were further verified utilising reverse transcription quantitative PCR (RT-qPCR), Western blot (WB), ELISA and immunofluorescence (IF) techniques., Results: Following treatment with PAE + GLY, hyperalgesia threshold and 5-hydroxytryptamine (5-HT) levels increased, and migraine-like head scratching, histamine and calcitonin gene-related peptide (CGRP) levels were reduced. RNA-Seq experiments revealed that PAE + GLY upregulated the expression of Glutamate decarboxylase 2 (GAD2) and γ-aminobutyric acid type B receptor subunit 2 (GABBR2) genes. This upregulation activated the GABAergic synapse pathway, effectively inhibiting migraine attacks. Further validation demonstrated an increase in γ-aminobutyric acid (GABA) content in cerebrospinal fluid post PAE + GLY treatment, coupled with increased expression of dural GAD2, GABBR2 and transient receptor potential channel M8 (TRPM8). Consequently, this inhibited the expression of dural cAMP-dependent protein kinase catalytic subunit alpha (PRKACA) and transient receptor potential channel type 1 (TRPV1), subsequently downregulating p-ERK1/2, p-AKT1, IL-1β and TNF-α., Conclusions: Our findings underscore that PAE + GLY ameliorates inflammatory hyperalgesia migraine by upregulating inhibitory neurotransmitters and modulating the GABBR2/TRPM8/PRKACA/TRPV1 pathway., Competing Interests: Declaration of competing interest There are no conflicts of interest to declare, and all the authors have approved this manuscript for publication., (Copyright © 2024. Published by Elsevier B.V.)

Fibroblast growth factor (FGF)-21 is a salient liver-derived endocrine regulator for metabolism of glucose and triglyceride as well as bone remodeling. Previously, certain peptides in the FGF family have been shown to modulate calcium absorption across the intestinal epithelia. Since FGF21 receptor, i.e., FGF receptor-1, is abundantly expressed in the enterocytes, there was a possibility that FGF21 might exert direct actions on the intestine. Herein, a large-scale production of recombinant FGF21 at the multi-gram level was developed in order to minimize variations among various batches. In the oral glucose tolerance test, recombinant FGF21 was found to reduce plasma glucose levels in mice fed high-fat diet. A series of experiments applying radioactive tracer 45 Ca in Ussing chamber showed that FGF21 potentiated the stimulatory effect of low-dose 1,25-dihydroxyvitamin D 3 [10 nM 1,25(OH) 2 D 3 ] on the transepithelial calcium transport across intestinal epithelium-like Caco-2 monolayer. FGF21 + 1,25(OH) 2 D 3 also decreased transepithelial resistance, but had no effect on epithelial potential difference or short-circuit current. Furthermore, 1,25(OH) 2 D 3 alone upregulated the Caco-2 mRNA expression of the major apical calcium channels, i.e., transient receptor potential vanilloid subfamily member 6 (TRPV6), which was further elevated by a combination of FGF21 and 1,25(OH) 2 D 3 , consistent with the upregulated TRPV6 protein expression in enterocytes of FGF21-treated mice. However, FGF21 was without effects on the mRNA expression of voltage-gated calcium channel 1.3, calbindin-D 9k , plasma membrane Ca 2+ -ATPase 1b, claudin-12 or claudin-15. In conclusion, FGF21 did exert a direct action on the intestinal epithelial cells by potentiating the 1,25(OH) 2 D 3 -enhanced calcium transport, presumably through the upregulation of TRPV6 expression., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Pain, detected by nociceptors, is an integral part of injury, yet whether and how it can impact tissue physiology and recovery remain understudied. Here, we applied chemogenetics in mice to locally activate dermal TRPV1 innervations in naive skin and found that it triggered new regenerative cycling by dormant hair follicles (HFs). This was preceded by rapid apoptosis of dermal macrophages, mediated by the neuropeptide calcitonin gene-related peptide (CGRP). TRPV1 activation also triggered a macrophage-dependent induction of osteopontin (Spp1)-expressing dermal fibroblasts. The neuropeptide CGRP and the extracellular matrix protein Spp1 were required for the nociceptor-triggered hair growth. Finally, we showed that epidermal abrasion injury induced Spp1-expressing dermal fibroblasts and hair growth via a TRPV1 neuron and CGRP-dependent mechanism. Collectively, these data demonstrated a role for TRPV1 nociceptors in orchestrating a macrophage and fibroblast-supported mechanism to promote hair growth and enabling the efficient restoration of this mechano- and thermo-protective barrier after wounding., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Preterm labor is the leading cause of neonatal death and major morbidity but remains a poorly understood process with no effective tocolytic therapies. Recent work has identified the transient receptor potential vanilloid 4 (TRPV4) channel, a membrane calcium channel upregulated in uterine smooth muscle through gestation, as integral in the transition from quiescence to contraction in the gravid uterus. The present study builds upon these findings and investigates regulation of the TRPV4 channel during pregnancy in the murine and human uterus by micro-RNA 203 (miR-203). We find a progressive decrease in miR-203 expression during gestation, accompanied by a reciprocal increase in TRPV4 mRNA and protein expression. In human uterine smooth muscle cells (UtSMC), miR-203 overexpression reduces, and si-RNA-mediated silencing increases, TRPV4 expression. Studies using murine UtSMC demonstrate that miR-203 expression modulates TRPV4-mediated cytosolic calcium entry and contractility. Consistent with these findings, the response to pharmacologic TRVP4 agonists is increased in myometrial tissue from miRNA203 -/- mice compared to control mice. Moreover, we demonstrate that miR-203 binds specifically on the promoter region of TRPV4 to decrease expression. In murine inflammatory models of preterm labor, miR-203 overexpression prolongs pregnancy. Estradiol (E2) decreases miR-203 and increases TRPV4 expression, providing a potential physiologic link for the unique reciprocal relationship in UtSMC. Taken together, these findings provide evidence that miR-203 modulates uterine contractility during pregnancy via negative regulation of TRPV4. These findings support the hypothesis that targeting miR-203 holds the promise of an entirely novel approach to prevent prematurity and treat preterm labor., (© 2024 Federation of American Societies for Experimental Biology.)

Problem: What is the effect of SR-16234 (SR), a selective estrogen receptor (ER) modulator, on human endometriotic stromal cells (ESCs)?, Method of Study: Endometriotic tissues were obtained from 21 patients undergoing laparoscopic surgery for ovarian endometriomas (OEs). Normal eutopic endometrium during the luteal phase was obtained from 18 patients without endometriosis. ESCs isolated from OEs and normal eutopic endometrial stromal cells (NESCs) were cultured with SR and subsequently exposed to tumor necrosis factor (TNF)-α. After 48 h of incubation, the effect of SR on cell proliferation was evaluated by the WST-8 assay. The gene expressions of inflammatory and pain-related factors, including interleukin (IL)-6, IL-8, cyclooxygenase (COX)-2, transient receptor potential vanilloid (TRPV)1, ESR1, and ESR2, were evaluated by real-time RT-PCR. The phosphorylation of Inhibitor κBα (IκBα), extracellular signal-regulated kinase (ERK)1/2, and Protein Kinase B (AKT) were evaluated by western blot analysis. ILs, prostaglandin (PG) E2, and intranuclear p65 syntheses were assessed by ELISA., Results: SR treatment repressed TNF-α-induced proliferation by 20% in ESCs but not　NESCs. SR also reduced IL-6, IL-8, COX-2, TRPV1, ESR1, and ESR2 mRNA expressions and ILs protein, and PGE2 synthesis in ESCs, whereas in NESCs, only TRPV1 mRNA expression was decreased. SR suppressed TNF-α-induced phosphorylated IκBα levels by approximately 50%, and intranuclear p65 protein was reduced by 30% compared to addition of only TNF-α in ESCs. However, SR did not affect the phosphorylation of AKT and ERK1/2., Conclusions: SR appears to be a potential therapeutic agent for endometriosis by suppressing inflammatory and pain-related factor expressions by inhibiting the nuclear factor-kappa B pathway., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Aim: This investigation addresses Piezo1's expression and mechanistic role in dorsal root ganglion (DRG) neurons and delineates its participation in mechanical and inflammatory pain modulation., Methods: We analyzed Piezo1's expression patterns in DRG neurons and utilized Piezo1-specific shRNA to modulate its activity. Electrophysiological assessments of mechanically activated (MA) currents in DRG neurons and behavioral analyses in mouse models of inflammatory pain were conducted to elucidate Piezo1's functional implications. Additionally, we investigated the excitability of TRPV1-expressing DRG neurons, particularly under inflammatory conditions., Results: Piezo1 was preferentially expressed in DRG neurons co-expressing the TRPV1 nociceptor marker. Knockdown of Piezo1 attenuated intermediately adapting MA currents and lessened tactile pain hypersensitivity in models of inflammatory pain. Additionally, silencing Piezo1 modified the excitability of TRPV1-expressing neurons under inflammatory stress., Conclusion: Piezo1 emerges as a key mediator in the transmission of mechanical and inflammatory pain, indicating its potential as a novel target for pain management therapies. Our finding not only advances the understanding of nociceptive signaling but also emphasizes the therapeutic potential of modulating Piezo1 in the treatment of pain., (© 2024 The Author(s). Acta Physiologica published by John Wiley & Sons Ltd on behalf of Scandinavian Physiological Society.)

Flushing is a typical physiological reaction to high emotional reactions. It is characterized by cutaneous vasodilation and a feeling of warmth and skin redness, especially in the face areas. Flushing is frequently linked to social anxiety, but it can also be a sign of a number of benign and malignant medical disorders. The study focuses on niacin-induced flushing, a well-researched side effect of the niacin, a drug which increases cholesterol levels. Niacin-induced flushing occurs when the hydroxycarboxylic acid receptor 2 (HCA2 or GPR109A) is activated. This starts a signaling cascade that releases prostaglandins, especially PGD2, which causes cutaneous vasodilation. Furthermore, niacin directly interacts with the transient receptor potential (TRP) channel TRPV1, offering a different, non-prostaglandin-based explanation for flushing brought on by niacin, highlighting the intricate physiological mechanisms behind this widespread occurrence. The review delves deeper into the advantages of niacin treatment for the cardiovascular system, highlighting how it can improve lipid profiles and lower cardiovascular events when used with statins. To sum it up, this study offers a thorough understanding of flushing, including its physiological foundation, many etiologies, diagnostic difficulties, and the subtleties of flushing caused by niacin. The investigation of innovative dose forms and nanomedicine highlights the continuous endeavors to improve patient compliance and reduce side effects, laying the groundwork for further developments in flushing treatment., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Aging is associated with a decline in oral immune function, marked by reduced levels of antimicrobial peptides such as defensins. Capsaicin, a bioactive component found in chili peppers, has been theorized to modulate immune responses through specific receptor pathways. This study examined the effects of aging on oral defensin levels and the potential mitigating role of capsaicin, mediated by the immune response in oral tissues. We conducted a comparative analysis between young and aged mice, with or without capsaicin supplementation, for 3 months. The effect of capsaicin was also studied in vitro in senescence-induced human oral keratinocytes. We found that aging did not reduce defensin levels uniformly but did so in some instances. Capsaicin treatment increased defensin levels in these cases, potentially through transient receptor potential cation channel subfamily V member 1 (TRPV1)-mediated pathways in the oral cavity. Capsaicin supplementation may counteract age-related declines in oral defensin levels, enabling the maintenance of oral immune function during aging., (© 2024 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.)

The prevalence of bacterial infections significantly increases among patients with severe traumatic brain injury (STBI), leading to a notable rise in mortality rates. While immune dysfunctions are linked to the incidence of pneumonia, our observations indicate that endogenous pathogens manifest in the lungs post-STBI due to the migration of gut commensal bacteria. This translocation involves gut-innervating nociceptor sensory neurons, which are crucial for host defense. Following STBI, the expression of transient receptor potential vanilloid 1 (TRPV1) in dorsal root ganglion (DRG) neurons significantly decreases, despite an initial brief increase. The timing of TRPV1 defects coincides with the occurrence of pulmonary infections post-STBI. This alteration in TRPV1 + neurons diminishes their ability to signal bacterial injuries, weakens defense mechanisms against intestinal bacteria, and increases susceptibility to pulmonary infections via bacterial translocation. Experimental evidence demonstrates that pulmonary infections can be successfully replicated through the chemical ablation and gene interference of TRPV1 + nociceptors, and that these infections can be mitigated by TRPV1 activation, thereby confirming the crucial role of nociceptor neurons in controlling intestinal bacterial migration. Furthermore, TRPV1 + nociceptors regulate the immune response of microfold cells by releasing calcitonin gene-related peptide (CGRP), thereby influencing the translocation of gut bacteria to the lungs. Our study elucidates how changes in nociceptive neurons post-STBI impact intestinal pathogen defense. This new understanding of endogenous risk factors within STBI pathology offers novel insights for preventing and treating pulmonary infections., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Background: Visceral hypersensitivity is considered the core pathophysiological mechanism that causes abdominal pain in patients with irritable bowel syndrome (IBS). Fungal dysbiosis has been proved to contribute to visceral hypersensitivity in IBS patients. However, the underlying mechanisms for Dectin-1, a major fungal recognition receptor, in visceral hypersensitivity are poorly understood. This study aimed to explore the role of Dectin-1 in visceral hypersensitivity and elucidate the impact of Dectin-1 activity on the function of transient receptor potential vanilloid type 1 (TRPV1)., Methods: Visceral hypersensitivity model was established by the intracolonic administration of 0.1 mL TNBS (130 μg/mL in 30% ethanol) in the male mice. Fluconazole and nystatin were used as fungicides. Laminarin, a Dectin-1 antagonist and gene knockout (Clec7a -/- ) mice were used to interrupt the function of Dectin-1. Colorectal distension-electromyogram recording was performed to assess visceral sensitivity. Immunostaining experiment was performed to determine the localization of Dectin-1 in dorsal root ganglion (DRG) neurons. Calcium imaging study was performed to assay TRPV1-mediated calcium influx in acutely dissociated DRG neurons., Results: Pretreatment with fungicides, administration of laminarin or genetic deletion of Clec7a alleviated TNBS-induced visceral hypersensitivity in male mice. The expression of Dectin-1 was upregulated in the DRG and colon of TNBS-treated mice. Colocalization of Dectin-1 and TRPV1 was observed in DRG neurons. Importantly, pretreatment with curdlan, a Dectin-1 agonist, increased TRPV1-mediated calcium influx., Conclusions: Dectin-1 contributes to visceral hypersensitivity in IBS or in inflammatory bowel disease in remission and activation of Dectin-1 induces TRPV1 sensitization., Significance Statement: This work provides direct evidence for the functional regulation of TRPV1 channel by Dectin-1 activity, proposing a new mechanism underlying TRPV1 sensitization. Control of intestinal fungi might be beneficial for the treatment of refractory abdominal pain in patients with IBS or IBD in remission., (© 2024 European Pain Federation ‐ EFIC ®.)

Abstract: Cannabidiol (CBD), the main nonpsychoactive cannabinoid of cannabis, holds promise for nonaddictive treatment of pain. Although preclinical studies have been encouraging, well-controlled human trials have been largely unsuccessful. To investigate this dichotomy and better understand the actions of CBD, we used high-content calcium imaging with automated liquid handling and observed broad inhibition of neuronal activation by a host of ionotropic and metabotropic receptors, including transient receptor potential (Trp) and purinergic receptors, as well as mediators of intracellular calcium cycling. To assess the effect of CBD on overall nociceptor electrical activity, we combined the light-activated ion channel channelrhodposin in TRPV1-positive nociceptors and a red-shifted calcium indicator and found that 1 µM CBD profoundly increased the optical threshold for calcium flux activation. Experiments using traditional whole-cell patch-clamp showed increase of nociceptor activation threshold at submicromolar concentrations, but with unusually slow kinetics, as well as block of voltage-activated currents. To address a more integrated capacity of CBD to influence nociceptor sensitization, a process implicated in multiple pain states, we found that submicromolar concentrations of CBD inhibited sensitization by the chemotherapeutic drug vincristine. Taken together, these results demonstrate that CBD can reduce neuronal activity evoked by a strikingly wide range of stimuli implicated in pain signaling. The extensive effects underscore the need for further studies at substantially lower drug concentrations, which are more likely to reflect physiologically relevant mechanisms. The slow kinetics and block raise biophysical questions regarding the lipophilic properties of CBD and its action on channels and receptors within membranes., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the International Association for the Study of Pain.)

Background: As a mechanosensitive cation channel and key regulator of vascular barrier function, endothelial transient receptor potential vanilloid type 4 (TRPV4) contributes critically to ventilator-induced lung injury and edema formation. Ca2+ influx via TRPV4 can activate Ca2+-activated potassium (KCa) channels, categorized into small (SK1-3), intermediate (IK1), and big (BK) KCa, which may in turn amplify Ca2+ influx by increasing the electrochemical Ca2+ gradient and thus promote lung injury. The authors therefore hypothesized that endothelial KCa channels may contribute to the progression of TRPV4-mediated ventilator-induced lung injury., Methods: Male C57Bl/6J mice were ventilated for 2 h with low or high tidal volumes in the presence or absence of the nonselective KCa antagonists apamin and charybdotoxin or the selective IK1 antagonist TRAM34. Lung injury was similarly assessed in overventilated, endothelial-specific TRPV4-deficient mice or TRAM34-treated C57Bl/6J mice challenged with intratracheal acid installation. Changes in intracellular calcium Ca2+ concentration ([Ca2+]i) were monitored by real-time imaging in isolated-perfused lungs in response to airway pressure elevation or in human pulmonary microvascular endothelial cells in response to TRPV4 activation with or without inhibition of KCa channels. Analogously, changes in intracellular potassium concentration ([K+]i) and membrane potential were imaged in vitro., Results: Endothelial TRPV4 deficiency or inhibition of KCa channels, and most prominently inhibition of IK1 by TRAM34, attenuated ventilator-induced lung injury as demonstrated by reduced lung edema, protein leak, and quantitative lung histology. All KCa antagonists reduced the [Ca2+]i response to mechanical stimulation or direct TRPV4 activation in isolated lungs. TRAM34 and charybdotoxin yet not apamin prevented TRPV4-induced potassium efflux and membrane hyperpolarization in human pulmonary microvascular endothelial cells. TRAM34 also attenuated the TRPV4 agonist-induced Ca2+ influx in vitro and reduced acid-induced lung injury in vivo., Conclusions: KCa channels, specifically IK1, act as amplifiers of TRPV4-mediated Ca2+ influx and establish a detrimental feedback that promotes barrier failure and drives the progression of ventilator-induced lung injury., (Copyright © 2024 American Society of Anesthesiologists. All Rights Reserved.)

Background: and Purpose: Chemotherapy-induced peripheral neuropathy (CIPN) constitutes a significant health problem due to the increasing prevalence and lack of therapies for treatment and prevention. While pivotal for routine cancer treatment, paclitaxel and vincristine frequently cause CIPN and impact the quality of life among cancer patients and survivors. Here, we investigate molecular mechanisms and drug transport in CIPN., Experimental Approach: Human sensory neurons were derived from induced pluripotent stem cells (iPSC-SNs), which were characterized using flow cytometry and immunolabeling. These iPSC-SNs were exposed to different concentrations of the two microtubule-targeting agents, paclitaxel and vincristine, with and without pre-exposure to inhibitors and inducers of efflux transporters. Neuronal networks were quantified via fluorescent staining against sensory neuron markers. Transcriptional effects of the chemotherapeutics were examined using quantitative polymerase chain reactions (qPCR)., Key Results: Paclitaxel exposure resulted in axonal retraction and thickening, while vincristine caused fragmentation and abolishment of axons. Both agents increased the mRNA expression of the pain receptor, transient receptor potential vanilloid (TRPV1), and highly induced neuronal damage, as measured by activating transcription factor 3 (ATF3) mRNA. iPSC-SNs express the efflux transporters, P-glycoprotein (P-gp, encoded by ABCB1) and multidrug resistance-associated protein 1 (MPR1, encoded by ABCC1). Modulation of efflux transporters indicate that P-gp and MRP1 play a role in modulating neuronal accumulation and neurotoxicity in preliminary experiments., Conclusion: and Implications: iPSC-SNs are a valuable and robust model to study the role of efflux transporters and other mechanistic targets in CIPN. Efflux transporters may play a role in CIPN pathogenesis as they regulate the disposition of chemotherapy to the peripheral nervous system, and they may present potential therapeutic targets for CIPN., Competing Interests: Declaration of competing interest T.B.S. has given paid lectures for Pfizer and Eisai, consulted for Pfizer, and been involved in a scientific collaboration with Novo Nordisk, unrelated to the work presented in this article. T.B.S. is an owner of the patent (WO2021043673) entitled “P-gp inducers as protectors against chemotherapy-induced side effects, such as peripheral neuropathy (CIPN) and hair loss”. O.P. is a shareholder of Signatope GmbH that offers assay development and service using immunoaffinity-LC-MS/MS technology. All other authors declared no conflicts of interest for this work., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Previously we showed hyperosmotic solution caused TRPV1-dependent NKCC1 activation in the lens by a mechanism that involved ERK1/2 signaling. In various tissues, integrins and the cytoskeletal network play a role in responses to osmotic stress. Here, we examined the association between integrins and TRPV1-dependent activation of NKCC1 in mouse lens epithelium. Wild-type (WT) lenses exposed to the integrin agonist leukadherin-1 (LA-1) for 10 min displayed a ~33% increase in the bumetanide-sensitive rate of Rb uptake indicating NKCC activation. Paclitaxel, a microtubule stabilizing agent, abolished the Rb uptake response. In primary cultured lens epithelium LA-1 caused a robust ERK1/2 activation response that was almost fully suppressed by paclitaxel. The TRPV1 agonist capsaicin caused a similar ERK1/2 activation response. Consistent with an association between integrins and TRPV1, the TRPV1 antagonist A889425 prevented the Rb uptake response to LA-1 as did the ERK inhibitor U0126. LA-1 did not increase Rb uptake by lenses from TRPV1 knockout mice. In cells exposed to a hyperosmotic stimulus, both the ERK1/2 activation and Rb uptake responses were prevented by paclitaxel. Taken together, the findings suggest TRPV1 activation is associated with integrins and the tubulin cytoskeleton. This aligned with the observation that LA-1 elicited a robust cytoplasmic calcium rise in cells from WT lenses but failed to increase calcium in cells from TRPV1 knockout lenses. The results are consistent with the notion that integrin activation by LA-1, or a hyperosmotic stimulus, causes TRPV1 channel opening and the consequent downstream activation of the ERK1/2 and NKCC1 responses., (© 2024 Wiley Periodicals LLC.)

Hypercalciuria is the most common metabolic risk factor in people with kidney stone disease. Its etiology is mostly multifactorial, although monogenetic causes of hypercalciuria have also been described. Despite the increased availability of genetic diagnostic tests, the vast majority of individuals with familial hypercalciuria remain unsolved. In this study, we investigated a consanguineous pedigree with idiopathic hypercalciuria. The proband additionally exhibited severe skeletal deformities and hyperparathyroidism. Whole-exome sequencing of the proband revealed a homozygous ultra-rare variant in TRPV5 (NM_019841.7:c.1792G>A; p.(Val598Met)), which encodes for a renal Ca 2+ -selective ion channel. The variant segregates with the three individuals with hypercalciuria. The skeletal phenotype unique to the proband was due to an additional pathogenic somatic mutation in GNAS (NM_000516.7:c.601C>T; p.(Arg201Cys)), which leads to polyostotic fibrous dysplasia. The variant in TRPV5 is located in the TRP helix, a characteristic amphipathic helix that is indispensable for the gating movements of TRP channels. Biochemical characterization of the TRPV5 p.(Val598Met) channel revealed a complete loss of Ca 2+ transport capability. This defect is caused by reduced expression of the mutant channel, due to misfolding and preferential targeting to the proteasome for degradation. Based on these findings, we conclude that biallelic loss of TRPV5 function causes a novel form of monogenic autosomal recessive hypercalciuria, which we name renal Ca 2+ -wasting hypercalciuria (RCWH). The recessive inheritance pattern explains the rarity of RCWH and underscores the potential prevalence of RCWH in highly consanguineous populations, emphasizing the importance of exploration of this disorder within such communities., Competing Interests: Competing interests The authors declare no competing interests. Ethics approval and consent to participate The study protocol was approved by the local ethics committees of Hacettepe University and Dr. Sami Ulus Obstetrics and Gynecology, Children Health and Disease Training and Research Hospital (GO21/446, 30.03.2021, and 2012-KAEK-15/2030, 22.01.2020). The study was conducted in accordance with the Declaration of Helsinki and written informed consent including publication of individual details was obtained from all participants and/or their parents. Additionally, written informed consent for publication of medical images was obtained for the proband., (© 2024. The Author(s).)

Given that the corneal epithelium is situated on the outermost part of the eye, its functions can be influenced by external temperatures and chemical substances. This study aimed to elucidate the expression profile of chemosensory receptors in corneal epithelial cells and analyze their role in eye function regulation. A comprehensive analysis of 425 chemosensory receptors in human corneal epithelial cells-transformed (HCE-T) revealed the functional expression of TRPV4. The activation of TRPV4 in HCE-T cells significantly increased the expression of membrane-associated mucins MUC1, MUC4, and MUC16, which are crucial for stabilizing tear films, with efficacy comparable to the active components of dry eye medications. The present study suggests that TRPV4, which is activated by body temperature, regulates mucin expression and proposes it as a novel target for dry eye treatment., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Yuko Terada reports financial support was provided by Japan Society for the Promotion of Science. Keisuke Ito reports financial support was provided by Japan Society for the Promotion of Science. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The salivary microbiota of Italian and sub-Saharan African individuals was investigated using Nanopore sequencing technology (ONT: Oxford Nanopore Technologies). We detected variations in community composition in relation to endogenous (ethnicity, sex, and diplotypic variants of the TRPV1 gene) and exogenous (sensitivity to capsaicin) factors. The results showed that Prevotella , Haemophilus , Neisseria , Streptococcus , Veillonella , and Rothia are the most abundant genera, in accordance with the literature. However, alpha diversity and frequency spectra differed significantly between DNA pools. The microbiota in African, male TRPV1 bb/ab diplotype and capsaicin low-sensitive DNA pools was more diverse than Italian, female TRPV1 aa diplotype and capsaicin high-sensitive DNA pools. Relative abundance differed at the phylum, genus, and species level.

Transient receptor potential vanilloid (TRPV) channel proteins belong to the superfamily of TRP proteins that form cationic channels in the animal cell membranes. These proteins have various subtype-specific functions, serving, for example, as sensors for pain, pressure, pH, and mechanical extracellular stimuli. The sensing of extracellular cues by TRPV4 triggers Ca 2+ -influx through the channel, subsequently coordinating numerous intracellular signaling cascades in a spatio-temporal manner. As TRPV channels play such a wide role in various cellular and physiological functions, loss or impaired TRPV protein activity naturally contributes to many pathophysiological processes. This review concentrates on the known functions of TRPV4 sensor proteins and their potential as a therapeutic target.

Background: Persistent innate and adaptive immune responses in the brain contribute to the progression of Alzheimer's disease (AD). APOE4, the most important genetic risk factor for sporadic AD, encodes apolipoprotein E4, which by itself is a potent modulator of immune response. However, little is known about the immune hub that governs the crosstalk between the nervous and the adaptive immune systems. Transient receptor potential vanilloid type 1 (TRPV1) channel is a ligand-gated, nonselective cation channel with Ca 2+ permeability, which has been proposed as a neuroprotective target in AD., Methods: Using Ca 2+ -sensitive dyes, dynamic changes of Ca 2+ in microglia were measured, including exogenous Ca 2+ uptake and endoplasmic reticulum Ca 2+ release. The mRFP-GFP-tagged LC3 plasmid was expressed in microglia to characterize the role of TRPV1 in the autophagic flux. Transcriptomic analyses and flow cytometry were performed to investigate the effects of APOE4 on brain microglia and T cells from APOE-targeted replacement mice with microglia-specific TRPV1 gene deficiency., Results: Both APOE4 microglia derived from induced pluripotent stem cells of AD patients and APOE4-related tauopathy mouse model showed significantly increased cholesterol biosynthesis and accumulation compared to their APOE3 counterparts. Further, cholesterol dysregulation was associated with persistent activation of microglia and elevation of major histocompatibility complex II-dependent antigen presentation in microglia, subsequently accompanied by T cell infiltration. In addition, TRPV1-mediated transient Ca 2+ influx mitigated cholesterol biosynthesis in microglia by suppressing the transcriptional activation of sterol regulatory element-binding protein 2, promoted autophagic activity and reduced lysosomal cholesterol accumulation, which were sufficient to resolve excessive immune response and neurodegeneration in APOE4-related tauopathy mouse model. Moreover, microglia-specific deficiency of TRPV1 gene accelerated glial inflammation, T cell response and associated neurodegeneration in an APOE4-related tauopathy mouse model., Conclusions: The findings provide new perspectives for the treatment of APOE4-dependent neurodegeneration including AD., (© 2024. The Author(s).)

Mitochondria play an important role in pressure overload-induced cardiac hypertrophy. The present study aimed to investigate the role of mitochondrial transient receptor potential vanilloid 3 (TRPV3) in myocardial hypertrophy. A 0.7 mm diameter U-shaped silver clip was used to clamp the abdominal aorta of Sprague Dawley (SD) rats and establish an animal model of abdominal aortic constriction (AAC). Rat H9C2 myocardial cells were treated with angiotensin II (Ang II) to establish a hypertrophic myocardial cell model, and TRPV3 expression was knocked down using TRPV3 small interfering RNA (siRNA). JC-1 probe was used to detect mitochondrial membrane potential (MMP). DHE probe was used to detect ROS generation. Enzyme activities of mitochondrial respiratory chain complex I and III and ATP production were detected by assay kits. Immunofluorescence staining was used to detect TRPV3 expression in H9C2 cells. Western blot was used to detect the protein expression levels of β-myosin heavy chain (β-MHC), mitochondrial TRPV3 and mitochondrial NOX4. The results showed that, in the rat AAC model heart tissue and H9C2 cells treated with Ang II, the protein expression levels of β-MHC, mitochondrial TRPV3 and mitochondrial NOX4 were up-regulated, MMP was decreased, ROS generation was increased, mitochondrial respiratory chain complex I and III enzyme activities were decreased, and ATP production was reduced. After knocking down mitochondrial TRPV3 in H9C2 cells, the protein expression levels of β-MHC and mitochondrial NOX4 were down-regulated, MMP was increased, ROS generation was decreased, mitochondrial respiratory chain complex I and III enzyme activities were increased, and ATP production was increased. These results suggest that mitochondrial TRPV3 in cardiomyocytes exacerbates mitochondrial dysfunction by up-regulating NOX4, thereby participating in the process of pressure overload-induced myocardial hypertrophy.

The regulation of adipose tissue homeostasis is essential for maintaining energy and metabolism balance in the body. The peripheral nervous system plays a crucial role in this process. Previous related research primarily focused on the sympathetic nervous system and its release of norepinephrine, while recent attention has shifted to the field of adipose sensory nerves. Studies demonstrate that external stimuli can activate adipose sensory nerves through pathways involving transient receptor potential vanilloid-1 (TRPV1), adipokines, and fatty acids, thereby transmitting signals to the brain. Emerging techniques, such as adipose nerve imaging and denervation of tissues, have revealed the critical role of sensory nerves in the glucose and lipid metabolism, thermogenic function, and vascular regulation of adipose tissue. This article comprehensively reviews the latest research on the regulation and function of sensory nerves in adipose tissue, with a focus on the impact of metabolic diseases on adipose sensory nerves. This review discusses current issues and prospects on the mechanisms behind neural regulation in adipose tissue, hoping to contribute to a comprehensive understanding and providing directions for future research.

Thermogenetics is a promising neuromodulation technique based on the use of heat-sensitive ion channels. However, on the way to its clinical application, a number of questions have to be addressed. First, to avoid immune response in future human applications, human ion channels should be studied as thermogenetic actuators. Second, heating levels necessary to activate these channels in vivo in brain tissue should be studied and cytotoxicity of these temperatures addressed. Third, the possibility and safety of chronic neuromodulation has to be demonstrated. In this study, we present a comprehensive framework for thermogenetic neuromodulation in vivo using the thermosensitive human ion channel hTRPV1. By targeting hTRPV1 expression to excitatory neurons of the mouse brain and activating them within a non-harmful temperature range with a fiber-coupled infrared laser, we not only induced neuronal firing and stimulated locomotion in mice, but also demonstrated that thermogenetics can be employed for repeated neuromodulation without causing evident brain tissue injury. Our results lay the foundation for the use of thermogenetic neuromodulation in brain research and therapy of neuropathologies., (© 2024. The Author(s).)

Background: Type 2 diabetes mellitus (T2DM) is a major 21st-century epidemic. T2DM elevates the risk of myocardial infarction and heart failure while also reducinges survival rates. Recently Ferroptosis has been found to be involved in the development of various cardiovascular diseases. TRPV1 is also a potential therapeutic target for cardioprotection. This study explores whether capsaicin, a transient receptor potential vanilloid receptor 1 (TRPV1) agonist, can prevent diabetic myocardial infarction-induced injury by inhibiting ferroptosis., Methods: T2DM model was induced by high-fat diet (HFD) feeding combined with streptozocin (STZ) injections, and the diabetic mice were treated with capsaicin(0.015 %) in their food. Myocardial infarction model was established as well. Mouse' general characteristics, cardiac function, and morphological histology were observed and analyzed. RNA-seq was used to investigate the possible mechanism of injury in AC16 cardiomyocytes cultured with high glucose and hypoxia. In addition, the potential mechanism of capsaicin against injury was further investigated in AC16 cardiomyocytes cultured with high glucose and hypoxia., Results: The RNA-seq analysis revealed that ferroptosis was associated with cell death induced by high-glucose in combination with hypoxia, and CAP treatment could effectively inhibit ferroptosis to enhance cell survival. In vivo studies demonstrated that CAP treatment significantly improved post-MI cardiac function, attenuated myocardial inflammation and fibrosis. Furthermore, it was observed that CAP reduced ferroptosis levels by activating TRPV1 in the heart, upregulating Nrf2 expression, promoting Nrf2 nuclear translocation and increasing the expression of the Nrf2 downstream molecule Heme oxygenase-1 (HMOX1)., Conclusions: Dietary capsaicin may inhibit cardiomyocyte ferroptosis through activation of myocardial TRPV1 and Nrf2/HMOX1 signaling pathway, which in turn exerts a protective effect on the myocardium after myocardial infarction in type 2 diabetic mice., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Burning mouth syndrome (BMS) is a chronic idiopathic orofacial pain disorder, characterized by persistent burning sensations and pain without clear pathological causes. Recent research suggests that small fiber neuropathy (SFN) may play a significant role in the neuropathic pain and sensory disturbances associated with BMS. Following PRISMA guidelines, this systematic review aims to evaluate and synthesize current evidence supporting SFN's involvement in BMS. The protocol is registered in PROSPERO (CRD42024555839). The results show eight studies reported reductions in nerve fiber density in tongue biopsies (ranging from 30% to 60%), along with morphological changes indicative of small fiber damage. Additionally, an increase in TRPV1-positive, NGF-positive, and P2X3-positive fibers, overexpression of Nav1.7, and slight underexpression of Nav1.9 mRNA were observed in BMS patients. Quantitative Sensory Testing in seven studies revealed sensory abnormalities such as reduced cool detection and cold pain thresholds. Blink reflex and corneal confocal microscopy also indicated peripheral and central small fiber damage, along with increased artemin mRNA expression. The evidence strongly supports SFN as a key factor in the pathophysiology of BMS, particularly due to reductions in nerve fiber density and altered sensory thresholds. However, variability across studies highlights the need for larger, standardized research to establish causal relationships and guide therapeutic strategies.

Background: The endocannabinoid system (ECS) is highly integrated with seemingly all physiological and pathophysiological processes in the body. There is increasing interest in utilizing bioactive plant compounds, for promoting health and improving production in livestock. Given the established interaction between phytochemicals and the ECS, there are many opportunities for identification and development of therapies to address a range of diseases and disorders. However, the ECS has not been thoroughly characterized in cattle, especially in the gastrointestinal tract. The objective of this study was to characterize the distribution and transcriptional abundance of genes associated with the endocannabinoid system in bovine tissues., Methods: Tissues including brain, spleen, thyroid, lung, liver, kidney, mesenteric vein, tongue, sublingual mucosa, rumen, omasum, duodenum, jejunum, ileum and colon were collected from 10-mo old Holstein steers (n = 6). Total RNA was extracted and gene expression was measured using absolute quantification real time qPCR. Gene expression of endocannabinoid receptors CNR1 and CNR2, synthesis enzymes DAGLA, DAGLB and NAPEPLD, degradation enzymes MGLL and FAAH, and transient receptor potential vanilloids TRPV3 and TRPV6 was measured. Data were analyzed in R using a Kruskal-Wallis followed by a Wilcoxon rank-sum test. Results are reported as the median copy number/20 ng of equivalent cDNA (CN) with interquartile range (IQR)., Results: The greatest expression of CNR1 and CNR2 was in the brain and spleen, respectively. Expression of either receptor was not detected in any gastrointestinal tissues, however there was a tendency (P = 0.095) for CNR2 to be expressed above background in rumen. Expression of endocannabinoid synthesis and degradation enzymes varied greatly across tissues. Brain tissue had the greatest DAGLA expression at 641 CN (IQR 52; P ≤ 0.05). DAGLB was detected in all tissues, with brain and spleen having the greatest expression (P ≤ 0.05). Expression of NAPEPLD in the gastrointestinal tract was lowest in tongue and sublingual mucosal. There was no difference in expression of NAPEPLD between hindgut tissues, however these tissues collectively had 592% greater expression than rumen and omasum (P ≤ 0.05). While MGLL was found to be expressed in all tissues, expression of FAAH was only above the limit of detection in brain, liver, kidney, jejunum and ileum. TRPV3 was expressed above background in tongue, rumen, omasum and colon. Although not different from each other, thyroid and duodenum had the greatest expression of TRPV6, with 285 (IQR 164) and 563 (IQR 467) CN compared to all other tissues (P < 0.05)., Conclusions: These data demonstrate the complex distribution and variation of the ECS in bovine tissues. Expression patterns suggest that regulatory functions of this system are tissue dependent, providing initial insight into potential target tissues for manipulation of the ECS., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Vanilloid analogs, which can activate transient receptor potential vanilloid 1 (TRPV1), have been classified into two types based on susceptibility to forskolin (FSK). Treatment of cells expressing TRPV1 with FSK enhances TRPV1 responses to capsaicin-type ligands while diminishing the responses to eugenol-type ligands. In this study, we determined the effect of FSK on the activation of TRPV1 stimulated with vanilloid ligands, through the influx of Ca2+ in HEK293T cells expressing TRPV1. Our findings suggest that the effects of FSK can be attributed to the phosphorylation of TRPV1, as evidenced by using a protein kinase A inhibitor and TRPV1 mutants at potential phosphorylation sites. Furthermore, we examined the structure-activity relationship of 13 vanilloid analogs. Our results indicated that vanilloid compounds could be classified into three types, that is the previously reported two types and a novel type of 10-shogaol, by which TRPV1 activation was insusceptible to the FSK treatment., (© The Author(s) 2024. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

Transient receptor potential vanilloid 4 (TRPV4) channels have been associated with numerous pulmonary pathologies, including hypertension, asthma, and acute lung injury. However, their role in the alveolar epithelium remains unclear. We performed impedance-based resistance measurements in primary differentiated alveolar epithelial type I (AT1) cells from wild-type (WT) and TRPV4-deficient (TRPV4-/-) C57/BL6J mice to detect changes in AT1 barrier integrity upon TRPV4 activation. Both pharmacological (GSK1016790A) and a low pH-driven activation of TRPV4 were quantified, and the downstream effects on adherens junctions were assessed through the Western blotting of epithelial cadherin (E-cadherin) protein levels. Importantly, a drop in pH caused a rapid decrease in AT1 barrier resistance and increased the formation of a ~35 kDa E-cadherin C-terminal fragment, with both effects significantly reduced in TRPV4-/- AT1 cells. Similarly, the pharmacological activation of TRPV4 in AT1 cells triggered an immediate transient loss of barrier resistance and the formation of the same E-cadherin fragment, which was again diminished by TRPV4 deficiency. Moreover, TRPV4-mediated E-cadherin cleavage was significantly reduced by GI254023X, an antagonist of a disintegrin and metalloprotease 10 (ADAM10). Our results confirm the role of TRPV4 in regulating alveolar epithelial barrier permeability and provide insight into a novel signaling pathway by which TRPV4-induced Ca 2+ influx stimulates metalloprotease-driven ectodomain shedding.

Chronic pain is a universal public health problem with nearly one third of global human involved, which causes significant distressing personal burden. After painful stimulus, neurobiological changes occur not only in peripheral nervous system but also in central nervous system where somatosensory cortex is important for nociception. Being an ion channel, transient receptor potential vanilloid 1 (TRPV1) act as an inflammatory detector in the brain. Thymic stromal lymphopoietin (TSLP) is a potent neuroinflammation mediator after nerve injury. Bleomycin is applied to treat dermatologic diseases, and its administration elicits local painful sensation. However, whether bleomycin administration can cause chronic pain remains unknown. In the present study, we aimed to investigate how mice develop chronic pain after receiving repeated bleomycin administration. In addition, the relevant neurobiological brain changes after noxious stimuli were clarified. C57BL/6 mice aged five- to six-weeks were randomly classified into two group, PBS (normal) group and bleomycin group which bleomycin was intradermally administered to back five times a week over a three-week period. Calibrated forceps testing was used to measure mouse pain threshold. Western blots were used to assess neuroinflammatory response; immunofluorescence assay was used to measure the status of neuron apoptosis, glial reaction, and neuro-glial communication. Bleomycin administration induced mechanical nociception and activated both TRPV1 and TSLP/TSLPR/pSTAT5 signals in mouse somatosensory cortex. Through these pathways, bleomycin not only activates glial reaction but also causes neuronal apoptosis. TRPV1 and TSLP/TSLPR/pSTAT5 signaling had co-labeled each other by immunofluorescence assay. Taken together, our study provides a new chronic pain model by repeated intradermal bleomycin injection by activating TRPV1 and glial reaction-mediated neuroinflammation via TSLP/TSLPR/pSTAT5 signals., Competing Interests: Declaration of Competing Interest The authors have no conflict of interest to declare., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Transmission is the first step for a microorganism to establish colonization in the respiratory tract and subsequent development of infectious disease. Streptococcus pneumoniae is a leading pathogen that colonizes the mucosal surfaces of the human upper respiratory tract and causes subsequent transmission and invasive infections especially in co-infection with influenza A virus. Host factors contributing to respiratory contagion are poorly understood. Transient receptor potential vanilloid (TRPV) channels have various roles in response to microoorganism. Inhibition of TRPV exacerbates invasive infection by Streptococcus pneumoniae , but it is unclear how TRPV channels influence pneumococcal transmission. Here, we describe the effect of inhibition of TRPV1 on pneumococcal transmission. We adopted a TRPV1-deficient infant mouse model of pneumococcal transmission during co-infection with influenza A virus. We also analyzed the expression of nasal mucin or pro-inflammatory cytokines. TRPV1 deficiency attenuated pneumococcal transmission and shedding during co-infection with influenza A virus. TRPV1 deficiency suppressed the expression of nasal mucin. In addition, there were increases in the expression of tumor necrosis factor-α and type I interferon, followed by the suppressed replication of influenza A virus in TRPV1-deficient mice. Inhibition of TRPV1 was shown to attenuate pneumococcal transmission by reducing shedding through the suppression of nasal mucin during co-infection with influenza A virus. Inhibition of TRPV1 suppressed nasal mucin by modulation of pro-inflammatory responses and regulation of replication of influenza A virus. TRPV1 could be a new target in preventive strategy against pneumococcal transmission., Competing Interests: The authors declare no conflict of interest.

Neuropathic pain, a common symptom of several disorders, exerts a substantial socioeconomic burden worldwide. Transient receptor potential vanilloid 1 (TRPV1), a non-selective cation channel predominantly ex-pressed in nociceptive neurons, plays a pivotal role in nociception, by detecting various endogenous and exogenous stimuli, including heat, pro-inflammatory mediators, and physical stressors. Dysregulation of TRPV1 signaling further contributes to the pathophysiology of neuropathic pain. Therefore, targeting TRPV1 is a promising strategy for developing novel analgesics with improved efficacy and safety profiles. Several pharmacological approaches to modulate TRPV1 activity, including agonists, antagonists, and biological TRPV1 RNA interference (RNAi, small interfering RNA [siRNA]) have been explored. Despite preclinical success, the clinical translation of TRPV1-targeted therapies has encountered challenges, including hyperthermia, hypothermia, pungency, and desensitization. Nevertheless, ongoing research efforts aim to refine TRPV1-targeted interventions through structural modifications, development of selective modulators, and discovery of natural, peptide-based drug candidates. Herein, we provide guidance for researchers and clinicians involved in the development of new interventions specifically targeting TRPV1 by reviewing the existing literature and highlighting current research activities. This study further discusses potential future research endeavors for enhancing the efficacy, safety, and tolerability of TRPV1 candidates, and thereby facilitates the translation of these discoveries into effective clinical interventions to alleviate neuropathic pain disorders., Competing Interests: Declaration of competing interest All authors declare no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Ursolic acid (UA), a pentacyclic triterpene, exhibits diverse pharmacological effects, including potential treatment for allergic diseases. It downregulates thymic stromal lymphopoietin (TSLP) and disrupts mast cell signaling pathways. However, the exact molecular mechanism by which UA interferes with mast cell action remains unclear. Therefore, the current study aimed to uncover molecular entities underlying the effect of UA on mast cells and its potential antipruritic effect, specifically investigating its modulation of key molecules such as TRPV4, PAR2, and MRGPRX2, which are involved in TSLP regulation and sensation. Calcium imaging experiments revealed that UA pretreatment significantly suppressed MRGPRX2 activation (and its mouse orthologue MrgprB2), a G protein-coupled receptor predominantly expressed in mast cells. Molecular docking predictions suggested potential interactions between UA and MRGPRX2/MrgprB2. UA pretreatment also reduced mast cell degranulation through MRGPRX2 and MrgprB2-dependent mechanisms. In a dry skin mouse model, UA administration decreased tryptase and TSLP production in the skin, and diminished TSLP response in the sensory neurons. While PAR2 and TRPV4 activation enhances TSLP production, UA did not inhibit their activity. Notably, UA attenuated compound 48/80-induced scratching behaviors in mice and suppressed spontaneous scratching in a dry skin model. The present study confirms the effective inhibition of UA on MRGPRX2/MrgprB2, leading to reduced mast cell degranulation and suppressed scratching behaviors. These findings highlight the potential of UA as an antipruritic agent for managing various allergy- or itch-related conditions., Competing Interests: Declaration of competing interest The authors state no conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Cancer is a global health challenge with rising incidence and mortality rates, posing significant concerns. The World Health Organization reports cancer as a leading cause of death worldwide, contributing to nearly one in six deaths. Cancer pathogenesis involves disruptions in cellular signaling pathways, resulting in uncontrolled cell growth and metastasis. Among emerging players in cancer biology, Transient Receptor Potential (TRP) channels, notably TRPV1, have garnered attention due to their altered expression in cancer cells and roles in tumorigenesis and progression. TRPV1, also known as the capsaicin receptor, is pivotal in cancer cell death and pain mediation, offering promise as a therapeutic target. Activation of TRPV1 triggers calcium influx and affects cell signaling linked to growth and death. Additionally, TRPV1 is implicated in cancer-induced pain and chemo-sensitivity, with upregulation observed in sensory neurons innervating oral cancers. Also, when capsaicin, a compound from chili peppers, interacts with TRPV1, it elicits a "hot" sensation and influences cancer processes through calcium influx. Understanding TRPV1's multifaceted roles in cancer may lead to novel therapeutic strategies for managing cancer-related symptoms and improving patient outcomes. The current review elucidates the comprehensive role of capsaicin in cancer therapy, particularly through the TRPV1 channel, highlighting its effects in various cells via different signaling pathways and discussing its limitations.

Regulation of ion channel expression on the plasma membrane is a major determinant of neuronal excitability, and identifying the underlying mechanisms of this expression is critical to our understanding of neurons. Here, we present two orthogonal strategies to label extracellular sites of the ion channel TRPV1 that minimally perturb its function. We use the amber codon suppression technique to introduce a non-canonical amino acid (ncAA) with tetrazine click chemistry, compatible with a trans-cyclooctene coupled fluorescent dye. Additionally, by inserting the circularly permutated HaloTag (cpHaloTag) in an extracellular loop of TRPV1, we can incorporate a fluorescent dye of our choosing. Optimization of ncAA insertion sites was accomplished by screening residue positions between the S1 and S2 transmembrane domains with elevated missense variants in the human population. We identified T468 as a rapid labeling site (∼5 min) based on functional and biochemical assays in HEK293T/17 cells. Through adapting linker lengths and backbone placement of cpHaloTag on the extracellular side of TRPV1, we generated a fully functional channel construct, TRPV1exCellHalo, with intact wild-type gating properties. We used TRPV1exCellHalo in a single molecule experiment to track TRPV1 on the cell surface and validate studies that show decreased mobility of the channel upon activation. The application of these extracellular label TRPV1 (exCellTRPV1) constructs to track surface localization of the channel will shed significant light on the mechanisms regulating its expression and provide a general scheme to introduce similar modifications to other cell surface receptors., (© 2024 Mott et al.)

Background: Transient receptor potential vanilloid 1 (TRPV1) cation channels, expressed on nociceptors, are well established as key contributors to abdominal pain in inflammatory bowel disease (IBD). Previous attempts at blocking these channels have been riddled with side effects. Here, we propose a novel treatment strategy, utilizing the large pore of TRPV1 channels as a drug delivery system to selectively inhibit visceral nociceptors., Methods: We induced colitis in rats using intrarectal dinitrobenzene sulfonic acid. Visceral hypersensitivity, spontaneous pain, and responsiveness of the hind paws to noxious heat stimuli were examined before and after the intrarectal application of membrane-impermeable sodium channel blocker (QX-314) alone or together with TRPV1 channel activators or blockers., Results: Intrarectal co-application of QX-314 with TRPV1 channel activator capsaicin significantly inhibited colitis-induced gut hypersensitivity. Furthermore, in the model of colitis, but not in naïve rats, QX-314 alone was sufficient to reverse gut hypersensitivity. The blockade of TRPV1 channels prevented this effect of QX-314. Finally, applying QX-314 alone to the inflamed gut inhibited colitis-induced ongoing pain., Conclusions: Selective silencing of gut nociceptors by a membrane-impermeable sodium channel blocker entering via exogenously or endogenously activated TRPV1 channels diminishes IBD-induced gut hypersensitivity. The lack of effect on naïve rats suggests a selective analgesic effect in the inflamed gut. Our results suggest that in the colitis model, TRPV1 channels are tonically active. Furthermore, our results emphasize the role of TRPV1-expressing nociceptive fibers in colitis-induced pain. These findings provide proof of concept for using charged activity blockers for the blockade of IBD-associated abdominal pain., (© The Author(s) 2024. Published by Oxford University Press on behalf of Crohn’s & Colitis Foundation. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Introduction: The growing prevalence and lack of effective pain therapies for knee osteoarthritis (KOA) results in a substantial unmet need for novel analgesic therapies. The transient receptor potential vanilloid 1 (TRPV1) receptor is expressed in subsets of nociceptive sensory neurons and has major roles in pain transmission and regulation. In the structures of the knee joint, nociceptors are present in abundance., Areas Covered: TRPV1-expressing nociceptors in the knee represent a rational target to modulate activity at the origin of the pain pathway in KOA and may avoid systemic side effects seen with currently available analgesics. TRPV1 antagonists can induce analgesia, but hyperthermia and thermal hypesthesia side effects have limited their utility. Clinical development of TRPV1 agonists for pain management has progressed further than that of TRPV1 antagonists. Capsaicin and resiniferatoxin have provided proof-of-concept for the modulation of TRPV1 activity in KOA., Expert Opinion: Intra-articular administration of TRPV1 agonists enables direct delivery to target nerve terminals in the knee, offering a potentially transformative approach for the management of pain associated with KOA. Here, we explore the advances in understanding innervation of the knee joint in KOA, the role of TRPV1-expressing neurons and progress in developing TRPV1 modulators for KOA.

Background: Degeneration of nucleus pulposus (NP) cells involves multiple factors. The relationship between the canonical Wnt/β-catenin signaling pathway and matrix metalloproteinases (MMPs) is important in cellular senescence. Protein kinase C (PKC), an intermediate of the non-canonical Wnt pathway stimulated by phorbol myristate acetate (PMA), possibly prevents NP cell senescence, although not yet demonstrated in human-based studies. This study aimed to investigate the effect of PMA stimulation on the non-canonical and canonical Wnt pathways and MMP expression in human NP cells to ascertain its inhibitory effects on the senescence of NP cells., Methods: Human disc tissues of Pfirrmann grades 1 and 2 were collected from patients during spinal surgery and subsequently cultured. Protein and ribonucleic acid (RNA) were isolated from NP cells treated with PMA (400 nM) for 24 hours. Expression of MMP1, MMP13, tissue inhibitor of matrix metalloproteinase 1 (TIMP1), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), transient receptor potential vanilloid 4 (TRPV4), interleukin-6 (IL-6), and β-catenin were detected using western blot analysis. Messenger RNA (mRNA) expression of type II collagen and glycosaminoglycan (GAG) were analyzed using reverse transcription polymerase chain reaction. IL-6 and prostaglandin E2 (PGE 2 ) levels were measured using enzyme-linked immunosorbent assay., Results: Expression of PKC-δ (intermediate of the non-canonical Wnt pathway) and β-catenin (intermediate of the canonical Wnt pathway) was increased by PMA treatment. The mRNA levels of type II collagen and GAG increased; however, their protein levels were not altered. PMA treatment increased the expression of MMP1, TIMP1, ADAMTS5, IL-6, PGE 2 , and TRPV4; however, the expression of MMP13 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) was unaltered., Conclusions: PMA activated PKC-δ, affecting the non-canonical Wnt pathway; however, its effect on β-catenin in the canonical Wnt pathway was limited. β-catenin activation through the TRPV4 channel led to increased expression of MMP1 and ADAMTS5 and that of IL-6 and PGE 2 owing to NF-κB expression. Consequently, the degeneration of NP cells was not prevented., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2024 by The Korean Orthopaedic Association.)

Transient receptor potential vanilloid 3 channel (TRPV3) is closely associated with skin inflammation, but there is a lack of effective and specific inhibitors for clinical use. In this study, we identified antimalarial hydroxychloroquine (HCQ) as a selective TRPV3 inhibitor following the prediction by network pharmacology data analysis. In whole-cell patch-clamp recordings, HCQ inhibited the current of the TRPV3 channel, with an IC50 of 51.69 ± 4.78 μM. At the single-channel level, HCQ reduced the open probability of TRPV3 and decreased single-channel conductance. Molecular docking and site-directed mutagenesis confirmed that residues in the pore domain were critical for the activity of HCQ. In vivo, HCQ effectively reduced carvacrol-induced epidermal thickening, erythema, and desquamation. Additionally, the serum immunoglobulin E and inflammatory factors such as tumor necrosis factor-α and interleukin-6 were markedly decreased in the dorsal skin tissues in the HCQ treatment group, as compared to the model group. Our results suggested the antimalarial HCQ may represent a potential alleviator for treating skin inflammation by inhibiting TRPV3 channels., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Transient receptor potential vanilloid type 4 (TRPV4) is a versatile ion channel with diverse roles in immune cells, including macrophages. While its function in inflammation remains debated, we investigated its role in regulating IL-10 production and its impact on macrophage reprogramming during inflammation., Methods: We investigated the connection between TRPV4 activation and CREB-mediated IL-10 production during inflammation. Notably, this signaling pathway was found to reprogram macrophages and enhance their ability to resist inflammatory damage. The experiments were conducted on primary macrophages and were further corroborated by animal studies., Results: In response to TRPV4 activation during inflammation, we observed a significant increase in intracellular Ca 2+ levels, which triggered the activation of the transcription factor CREB, subsequently upregulating IL-10 production. This IL-10 played a pivotal role in reprogramming macrophages to withstand inflammatory damage. Using a mouse model of acute lung injury (ALI), we confirmed that TRPV4 activation during ALI led to IL-10 secretion, but this increase did not significantly contribute to inflammation resolution. Moreover, we found that TRPV4 prevented the accumulation of dysfunctional mitochondria in macrophages through the CREB-IL-10 axis during inflammation. Suppression of CREB or TRPV4 inhibition exacerbated mitochondrial dysfunction, while treatment with recombinant IL-10 mitigated these effects. Additionally, IL-10 induced mitophagy and cleared dysfunctional mitochondria in LPS-exposed cells., Conclusion: Our study highlights the essential role of TRPV4 in regulating IL-10 production and mitochondrial health in macrophages during inflammation. These findings contribute to understand the role of TRPV4 in immune responses and suggest potential therapeutic targets for modulating inflammation-induced cellular dysfunction., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The TRPV1 channel is actively involved in various neuronal processes and is found in various structures of the nervous system, including peripheral and central neurons, sensory ganglia, spinal cord, and various parts of the brain. Due to its ability to respond to various stimuli, TRPV1 can have a significant impact on the body's responses to stress. Studies indicate the involvement of TRPV1 in the regulation of anxiety behavior. Suppression of TRPV1 activity leads to a decrease in the level of anxiety in animals, which indicates the importance of this channel in psychoemotional regulation. A promising compound for inhibiting this channel is the APHC3 peptide, which is a selective receptor antagonist. The results obtained this study show that this peptide has a pronounced anxiolytic effect, reducing the level of anxiety in the studied animals., (© 2024. Pleiades Publishing, Ltd.)

Tanshinone IIA (TSA), the main lipo-soluble component from the dried rhizome of Salvia miltiorrhiza, has been shown to induce vasodilation. However, the underlying mechanisms remains unclear. This study aimed to investigate the effect of TSA on the vasodilation of small resistant arteries ex vivo. Vascular myography revealed that endothelial denudation reduced significantly the vasodilatory effect of TSA. Blocking transient receptor potential vanilloid 4 (TRPV4) channels prevented TSA-induced vasodilation. Whole-cell patch-clamp analysis revealed that the current passing through TRPV4 channels increased after TSA treatment in endothelial cells (ECs). This was attributed to reduced TRPV4 protein degradation along with its increased expression. The TRPV4 inhibitor HC-067047 lowed nitric oxide (NO) production and TSA-induced expression of endothelial nitric oxide synthase (eNOS). Moreover, it increased the production of cyclic guanosine monophosphate (cGMP) and protein kinase G (PKG). The present results indicate that TSA induces endothelium-dependent vasodilation, which is mediated by the TRPV4-NO-PKG signaling pathway. These findings highlight the potential of TSA, a compound known in traditional Chinese medicine as Danshen (Salvia miltiorrhiza), for future cardiovascular therapeutic strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

TRPV1 acts as a unique polymodal ion channel having distinct structure and gating properties. In this context, TRPV1-R575D represents a special mutant located at the inner lipid-water-interface (LWI) region that has less possibility of interaction with membrane cholesterol. In control conditions, this lab-generated mutant of TRPV1 shows no "ligand-sensitivity", reduced surface expression, reduced localization in the lipid rafts, yet induces high cellular lethality. Notably, the cellular lethality induced by TRPV1-R575D expression can be rescued by adding 5'I-RTX (a specific inhibitor of TRPV1) or by introducing another mutation in the next position, i.e. in TRPV1-R575D/D576R. In this work we characterized TRPV1-R575D and TRPV1-R575D/D576R mutants in different cellular conditions and compared with the TRPV1-WT. We report that the "ligand-insensitivity" of TRPV1-R575D can be rescued in certain conditions, such as by chelation of extracellular Ca 2+ , or by reduction of the membrane cholesterol. Here we show that Ca 2+ plays an important role in the channel gating of TRPV1-WT as well as LWI mutants (TRPV1-R575D, TRPV1-R575D/D576R). However, chelation of intracellular Ca 2+ or depletion of ER Ca 2+ did not have a significant effect on the TRPV1-R575D. Certain properties related to channel gating of mutant TRPV1-R575D/D576R can be rescued partially or fully in a context -dependent manner. Cholesterol depletion also alters these properties. Our data suggests that lower intracellular basal Ca 2+ acts as a pre-requisite for further opening of TRPV1-R575D. These findings enable better understanding of the structure-function relationship of TRPV1 and may be critical in comprehending the channelopathies induced by other homologous thermosensitive TRPVs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Current animal models of sensitive skin do not adequately reflect the objective symptoms or physiological manifestations observed in human sensitive skin., Objective: To construct and validate a sensitive skin model in mice., Methods: Tape stripping (TS) was used to induce partial mechanical disruption of the lipid film and stratum corneum. Subsequently, propylene glycol (PG) was applied to disrupt the lipid structure in the skin barrier, and capsaicin (CS) activate transient receptor potential vanilloid 1 (TRPV1) receptors of keratinocytes to simulate the formation of sensitive skin. Evident itching and tingling sensations, scaly skin, vasodilation, local congestion, increased transepidermal water loss (TEWL), elevated TRPV1 expression, and inflammatory symptoms were subsequently evaluated., Results: TS combined with PG and CS application resulted in skin flakes; skin barrier disruption; vascular dilation; increased itching, stinging, and inflammation; TRPV1 upregulation in the epidermis; and a significant increase in lactic acid-induced itching and stinging., Conclusion: Using a combination of TS and PG, and CS application, a mouse model of sensitive skin was successfully established involving various skin phenotypes and physiological manifestations, including skin flakes, vasodilation, increased blood flow and TEWL, itching and stinging sensations, inflammation, and elevated TRPV1 expression., (© 2024 The Author(s). Contact Dermatitis published by John Wiley & Sons Ltd.)

Objective: Transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel important in many physiological and pathophysiological processes, including pulmonary disease. Using a murine model, we previously demonstrated that TRPV4 mediates lung ischemia-reperfusion injury, the major cause of primary graft dysfunction after transplant. The current study tests the hypothesis that treatment with a TRPV4 inhibitor will attenuate lung ischemia-reperfusion injury in a clinically relevant porcine lung transplant model., Methods: A porcine left-lung transplant model was used. Animals were randomized to 2 treatment groups (n = 5/group): vehicle or GSK2193874 (selective TRPV4 inhibitor). Donor lungs underwent 30 minutes of warm ischemia and 24 hours of cold preservation before left lung allotransplantation and 4 hours of reperfusion. Vehicle or GSK2193874 (1 mg/kg) was administered to the recipient as a systemic infusion after recipient lung explant. Lung function, injury, and inflammatory biomarkers were compared., Results: After transplant, left lung oxygenation was significantly improved in the TRPV4 inhibitor group after 3 and 4 hours of reperfusion. Lung histology scores and edema were significantly improved, and neutrophil infiltration was significantly reduced in the TRPV4 inhibitor group. TRPV4 inhibitor-treated recipients had significantly reduced expression of interleukin-8, high mobility group box 1, P-selectin, and tight junction proteins (occludin, claudin-5, and zonula occludens-1) in bronchoalveolar lavage fluid as well as reduced angiopoietin-2 in plasma, all indicative of preservation of endothelial barrier function., Conclusions: Treatment of lung transplant recipients with TRPV4 inhibitor significantly improves lung function and attenuates ischemia-reperfusion injury. Thus, selective TRPV4 inhibition may be a promising therapeutic strategy to prevent primary graft dysfunction after transplant., Competing Interests: Conflict of Interest Statement The authors reported no conflicts of interest. The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest., (Copyright © 2024 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Background Information: The purinergic ligand-gated ion channel 7 receptor (P2X7R) is an ATP-gated ion channel that transmits extracellular signals and induces corresponding biological effects, transient receptor potential vanilloid type 1 (TRPV1) is a non-selective cation channel that maintains normal physiological functions; numerous studies showed that P2X7R and TRPV1 are associated with inflammatory reactions., Results: The effect of P2X7R knockdown in satellite glial cells (SGCs) on neuronal TRPV1 expression under high glucose and high free fat (HGHF) environment was investigated. P2X7 short hairpin RNA (shRNA) was utilized to downregulate P2X7R in SGCs, and treated and untreated SGCs were co-cultured with neuronal cell lines. The expression levels of inflammatory factors and signaling pathways in SGCs and neurons were measured using Western blot analysis, RT-qPCR, immunofluorescence, and enzyme-linked immunosorbent assays. Results suggested that P2X7 shRNA reduced the expression levels of P2X7R protein and mRNA in SGCs surrounding DRG neurons and downregulated the release of tumor necrosis factor-alpha and interleukin-1 beta via the Ca 2+ /p38 MAPK/NF-κB pathway. Additionally, the downregulation of P2X7R might decrease TRPV1 expression in neurons via the Ca 2+ /PKC-ɛ/p38 MAPK pathway., Conclusions: Reducing P2X7R expression in SCGs in an HGHF environment could decrease neuronal TRPV1 expression via the Ca 2+ /PKC-ɛ/p38 MAPK pathway., (© 2024 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.)

Pain is often one of the initial indicators of a viral infection, yet our understanding of how viruses induce pain is limited. Immune cells typically recognize viral nucleic acids, which activate viral receptors and signaling, leading to immunity. Interestingly, these viral receptors and signals are also present in nociceptors and are associated with pain. Here, we investigate the response of nociceptors to nucleic acids during viral infections, specifically focusing on the role of the viral signal, Stimulator of Interferon Genes (STING). Our research shows that cytosolic double-stranded DNA (dsDNA) from viruses, like herpes simplex virus 1 (HSV-1), triggers pain responses through STING expression in nociceptors. In addition, STING agonists alone can elicit pain responses. Notably, these responses involve the direct activation of STING in nociceptors through TRPV1. We also provided a proof-of-concept showing that STING and TRPV1 significantly contribute to the mechanical hypersensitivity induced by HSV-1 infection. These findings suggest that STING could be a potential therapeutic target for relieving pain during viral infections., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Changes in microcirculation lead to the progression of organ pathology in diabetes. Although neuroimmune interactions contribute to a variety of conditions, it is still unclear whether abnormal neural activities affect microcirculation related to diabetes. Using laser speckle contrast imaging, we examined the skin of patients with type 2 diabetes and found that their microvascular perfusion was significantly compromised. This phenomenon was replicated in a high-fat diet-driven murine model of type 2 diabetes-like disease. In this setting, although both macrophages and mast cells were enriched in the skin, only mast cells and associated degranulation were critically required for the microvascular impairment. Sensory neurons exhibited enhanced TRPV1 activities, which triggered mast cells to degranulate and compromise skin microcirculation. Chemical and genetic ablation of TRPV1+ nociceptors robustly improved skin microcirculation status. Substance P (SP) is a neuropeptide and was elevated in the skin and sensory neurons in the context of type 2 diabetes. Exogenous administration of SP resulted in impaired skin microcirculation, whereas neuronal knockdown of SP dramatically prevented mast cell degranulation and consequently improved skin microcirculation. Overall, our findings indicate a neuron-mast cell axis underlying skin microcirculation disturbance in diabetes and shed light on neuroimmune therapeutics for diabetes-related complications., (© 2024 by the American Diabetes Association.)