Transient Receptor Potential Ankyrin Research Articles

Paclitaxel Regulates TRPA1 Function and Expression Through PKA and PKC

Paclitaxel (PTX) is a frequently used anticancer drug that causes peripheral neuropathy. Transient receptor potential ankyrin 1 (TRPA1), a plasma membrane calcium channel, has been associated with PTX toxicity and with other chemotherapy agents such as oxaliplatin and vincristine. However, the effect of PTX on the functional expression and calcium currents of TRPA1 has not been determined. The present study shows the effect of PTX on TRPA1 activity in a neuronal cell line (SH-SY5Y). The effect of PTX on the expression of TRPA1 was assessed through quantitative PCR and Western blot analyses to determine the relative mRNA and protein expression levels. To assess the effect on calcium flux and currents, cells were exposed to PTX; simultaneously, a specific agonist and antagonist of TRPA1 were added to evaluate the differential response in exposed versus control cells. To assess the effect of PKA, PKC and PI3K on PTX-induced TRPA1 increased activity, selective inhibitors were added to these previous experiments. PTX increased the mRNA and protein expression of TRPA1 as well as the TRPA1-mediated Ca2+ currents and intracellular Ca2+ concentrations. This effect was dependent on AITC (a selective specific agonist) and was abolished with HC-030031 (a selective specific antagonist). The inhibition of PKA and PKC reduced the effect of PTX on the functional expression of TRPA1, whereas the inhibition of PI3K had no effects. PTX-induced neuropathy involves TRPA1 activity through an increase in functional expression and is regulated by PKA and PKC signaling. These findings support the role of the TRPA1 channel in the mechanisms altered by PTX, which can be involved in the process that lead to chemotherapy-induced neuropathy.

Modulatory effect of pomegranate extract on TRPA1, TRPM2 and caspase-3 expressions in colorectal cancer induction of mice

Abstract Objectives This study aimed to evaluate the effects of pomegranate fruit extract (PFE) on levels of transient receptor potential (TRP) channel and caspase-3 (Casp-3) expressions, tumor necrosis factor-α (TNF-α), total sialic acid (TSA), reduced glutathione (GSH), and malondialdehyde (MDA) in mice with induced colorectal cancer (CRC) by investigating effects of PFE on in vitro mitotic index (MI). Methods Different PFE concentrations on​​ MI against 0.3 μg/mL mitomycin-C (MMC) in cell culture were evaluated by binocular light microscopy. During in vivo applications on Balb/c mice, it was given once physiological saline to group I, PFE for ten weeks to group II, a single dose of azoxymethane (AOM) plus dextran sulfate sodium in drinking water (DSS) to group III, and AOM plus DSS plus PFE to group IV. Tissue samples were evaluated by western blotting, spectrophotometric, and histopathological methods. Results Expressions of Casp-3, TRP ankyrin 1 (TRPA1), and melastatin 2 (TRPM2) channels and TNF-α, TSA, GSH, and MDA concentrations in evaluated tissues had significantly better levels in PFE-treated groups compared to CRC-induced mice. Conclusions Results of the present study indicate that PFE application in mice with induced CRC may be an important modulator of TRPA1 and TRPM2 channels, apoptosis, and inflammatory response by decreasing oxidative stress.

Ectopic endometriosis in the pelvic cavity evokes bladder hypersensitivity via transient receptor potential ankyrin 1 hyperexpression in rats.

In women with chronic pelvic pain (CPP), interstitial cystitis/bladder pain syndrome (IC/BPS) and endometriosis frequently coexist. The mechanism of these diseases coexisting is explained by cross-sensitization between endometriosis and IC/BPS. The overlapped symptoms may be related to cross-sensitization with transient receptor potential vanilloid 1 (TRPV1) and/or transient receptor potential ankyrin 1 (TRPA1) hyperexpression. This study was aimed at exploring whether bladder hypersensitivity is evoked in the surgically induced ectopic endometriosis rat and whether TRPV1 and/or TRPA1 play a vital role. A total of 63 Sprague-Dawley female rats were divided into two groups, 39 for physiological examination and 24 for molecular analysis. Surgical induction of ectopic endometriosis (ENDO, n=27), surgical sham treatment (n=18), and treatment for endometriosis by GnRH analog (ENDO-G) (n=18) were performed. Bladder function was investigated by cystometry (for TRPV1 in the sham [n=6] and ENDO [n=9] groups and for TRPA1 in the sham [n=6], ENDO [n=9], and ENDO+G [n=9] groups), and TRPV1 and TRPA1 mRNA expressions were measured using real-time qPCR in the bladder and dorsal root ganglia (DRGs). On cystometry, the relative intercontraction interval (ICI) after/before resiniferatoxin (RTx; TRPV1 activator) infusion to the bladder showed no significant difference between the two groups, whereas relative ICI after/before allyl isothiocyanate (AITC; TRPA1 activator) infusion was significantly lower in the ENDO group than in the sham group. TRPA1 mRNA expression in the bladder and L5 DRG was considerably higher in the ENDO group than in the sham group on real-time qPCR. TRPA1 mRNA hyperexpression and bladder hypersensitivity after AITC infusion were reduced in the ENDO-G group. Bladder cross-sensitization in ENDO rats occurs in association with hyperexpression of TRPA1 at both the DRG and the bladder mucosa. This can be understood by the "cross-sensitization of endometriosis to bladder" theory explaining overlapping symptoms among BPS/IC and ectopic endometriosis.

Ligustrazine mitigates chronic venous disease-induced pain hyperalgesia through desensitization of inflammation-associated TRPA1 activity in DRG

Ethnopharmacological relevanceLigustrazine, an important active ingredient extracted from Ligusticum chuanxiong hort, has been widely used to cure cardiovascular diseases and exerts an analgesic effect. Aims of this studyThe aim of this study is to investigate whether ligustrazine mitigates chronic venous disease (CVeD)-induced pain and to explore its underlying mechanisms. Materials and methodsA mouse model of CVeD was established by vein ligature. Ligustrazine was administered intraperitoneally to CVeD mice for a single injection (20 mg/kg, 100 mg/kg, and 200 mg/kg) or once a day for three weeks (100 mg/kg and 200 mg/kg), and TRPA1 overexpressed HEK 293 cells were treated with ligustrazine (600 μM) in the presence of mustard oil (100 μM) for 2 min. Patch clamp and calcium imaging were used to measure the inhibitory response of ligustrazine on DRG neurons and TRPA1 transfected HEK293 cells. ResultsThe present results showed that mice receiving vein ligature surgery exhibited obvious pain hypersensitivity to mechanical, cold and thermal stimuli, whereas ligustrazine significantly reversed the pain hyperalgesia in CVeD mice. Furthermore, ligustrazine desensitized transient receptor potential ankyrin 1 (TRPA1) activity in the dorsal root ganglion (DRG) neurons, resulting in suppressing the DRG neuronal excitability in the CVeD mice. However, ligustrazine could not directly inhibit the response of TRPA1 transfected HEK293 cells to mustard oil. Strikingly, ligustrazine restricted the macrophage infiltration and decreased the mRNA levels of Interleukin-1β (IL-1β) and NOD-like receptor protein 3 (NLRP3) in the DRG neurons of the CVeD mice. ConclusionsThe present study provided evidence that ligustrazine alleviated pain hypersensitivity to mechanical, cold and thermal stimuli in CVeD mice. Ligustrazine could weaken the activity of TRPA1 in the DRG to mitigate CVeD-induced pain hyperalgesia mainly through inhibition of inflammation. Our findings identify that ligustrazine may be a new therapeutic agent for the treatment of CVeD-induced pain.

Intrarectal Capsazepine Administration Modulates Colonic Mucosal Health in Mice.

Antagonism of transient receptor potential vanniloid-1 (TRPV1) and desensitization of transient receptor potential ankyrin-1 (TRPA1) nociceptors alleviate inflammatory bowel diseases (IBD)-associated chronic pain. However, there is limited literature available about their role in regulating the mucosal layer, its interaction with host physiology, and luminal microbial community. The present study focuses on the effects’ intra rectal administration of capsazepine (modulator of TRPA1/TRPV1 expressing peptidergic sensory neurons) on colonic mucus production and gut health. We performed histological analysis, gut permeability alteration, gene expression changes, metabolite profiling, and gut microbial abundance in the ileum, colon, and cecum content of these animals. Intra rectal administration of capsazepine modulates TRPA1/TRPV1-positive nociceptors (behavioral pain assays) and resulted in damaged mucosal lining, increased gut permeability, and altered transcriptional profile of genes for goblet cell markers, mucus regulation, immune response, and tight junction proteins. The damage to mucosal lining prevented its role in enterosyne (short chain fatty acids) actions. These results suggest that caution must be exercised before employing TRPA1/TRPV1 modulation as a therapeutic option to alleviate pain caused due to IBD.

Different Involvement of ASIC and TRPA1 in Facial and Hindpaw Allodynia in Nitroglycerin-Induced Peripheral Hypersensitivities in Mice.

The pathophysiological mechanism underlying migraine-associated peripheral hypersensitivity remains unclear. Acid-sensing ion channels (ASICs) and transient receptor potential ankyrin 1 (TRPA1) are known to be causative pathogenic factors of mechanical and cold allodynia, respectively. Here, we sought to investigate their involvement in cold and mechanical allodynia of the face and hindpaws, respectively, in a mouse model of repetitive nitroglycerin (NTG)-induced migraine. NTG (10 mg/kg) was administered to the mice every other day for 9 days, followed 90 min later by HC-030031 (a TRPA1 blocker) or amiloride (a non-selective ASIC blocker). Mechanical or cold sensitivity of the hindpaw and facial regions was quantified using von-Frey filaments or acetone solution, respectively. Immunohistochemistry revealed that c-Fos expression was significantly increased in the trigeminal nucleus caudalis region but not in the spinal cord. Amiloride treatment only reduced NTG-induced hindpaw mechanical allodynia, whereas HC-030031 treatment only improved facial cold allodynia. Interestingly, the number of c-Fos positive cells decreased to a similar level in each drug treatment group. These findings demonstrate that facial cold allodynia and hindpaw mechanical allodynia are differentially mediated by activation of TRPA1 and ASIC, respectively, in mice with repetitive NTG-induced hypersensitivity.

Evolutionary Tuning of Transient Receptor Potential Ankyrin 1 Underlies the Variation in Heat Avoidance Behaviors among Frog Species Inhabiting Diverse Thermal Niches.

Environmental temperature is a critical factor for all forms of life, and thermal tolerance defines the habitats utilized by a species. Moreover, the evolutionary tuning of thermal perception can also play a key role in habitat selection. Yet, the relative importance of thermal tolerance and perception in environmental adaptation remains poorly understood. Thermal conditions experienced by anuran tadpoles differ among species due to the variation in breeding seasons and water environments selected by parental frogs. In the present study, heat tolerance and avoidance temperatures were compared in tadpoles from five anuran species that spatially and temporally inhabit different thermal niches. These two parameters were positively correlated with each other and were consistent with the thermal conditions of habitats. The species difference in avoidance temperature was 2.6 times larger than that in heat tolerance, suggesting the importance of heat avoidance responses in habitat selection. In addition, the avoidance temperature increased after warm acclimation, especially in the species frequently exposed to heat in their habitats. Characterization of the heat-sensing transient receptor potential ankyrin 1 (TRPA1) ion channel revealed an amphibian-specific alternatively spliced variant containing a single valine insertion relative to the canonical alternative spliced variant of TRPA1, and this novel variant altered the response to thermal stimuli. The two alternatively spliced variants of TRPA1 exhibited different thermal responses in a species-specific manner, which are likely to be associated with a difference in avoidance temperatures among species. Together, our findings suggest that the functional change in TRPA1 plays a crucial role in thermal adaptation processes.

The Bile Acid Membrane Receptor TGR5 in Cancer: Friend or Foe?

The G-protein-coupled bile acid receptor, Gpbar1 or TGR5, is characterized as a membrane receptor specifically activated by bile acids. A series of evidence shows that TGR5 induces protein kinase B (AKT), nuclear factor kappa-B (NF-κB), extracellular regulated protein kinases (ERK1/2), signal transducer and activator of transcription 3 (STAT3), cyclic adenosine monophosphate (cAMP), Ras homolog family member A (RhoA), exchange protein activated by cAMP (Epac), and transient receptor potential ankyrin subtype 1 protein (TRPA1) signaling pathways, thereby regulating proliferation, inflammation, adhesion, migration, insulin release, muscle relaxation, and cancer development. TGR5 is widely distributed in the brain, lung, heart, liver, spleen, pancreas, kidney, stomach, jejunum, ileum, colon, brown adipose tissue (BAT), white adipose tissue (WAT), and skeletal muscle. Several recent studies have demonstrated that TGR5 exerts inconsistent effects in different cancer cells upon activating via TGR5 agonists, such as INT-777, ursodeoxycholic acid (UDCA), and taurolithocholic acid (TLCA). In this review, we discuss both the ‘friend’ and ‘foe’ features of TGR5 by summarizing its tumor-suppressing and oncogenic functions and mechanisms.

The Association between TRP Channels Expression and Clinicopathological Characteristics of Patients with Pancreatic Adenocarcinoma.

Pancreatic adenocarcinoma (PDAC) has low survival rates worldwide due to its tendency to be detected late and its characteristic desmoplastic reaction, which slows the use of targeted therapies. As such, the discovery of new connections between genes and the clinicopathological parameters contribute to the search for new biomarkers or targets for therapy. Transient receptor potential (TRP) channels are promising tools for cancer therapy or markers for PDAC. Therefore, in this study, we selected several genes encoding TRP proteins previously reported in cellular models, namely, Transient Receptor Potential Cation Channel Subfamily V Member 6 (TRPV6), Transient receptor potential ankyrin 1 (TRPA1), and Transient receptor potential cation channel subfamily M (melastatin) member 8 (TRPM8), as well as the TRPM8 Channel Associated Factor 1 (TCAF1) and TRPM8 Channel Associated Factor 2 (TCAF2) proteins, as regulatory factors. We analyzed the expression levels of tumors from patients enrolled in public datasets and confirmed the results with a validation cohort of PDAC patients enrolled in the Clinical Institute Fundeni, Romania. We found significantly higher expression levels of TRPA1, TRPM8, and TCAF1/F2 in tumoral tissues compared to normal tissues, but lower expression levels of TRPV6, suggesting that TRP channels have either tumor-suppressive or oncogenic roles. The expression levels were correlated with the tumoral stages and are related to the genes involved in calcium homeostasis (Calbindin 1 or S100A4) or to proteins participating in metastasis (PTPN1). We conclude that the selected TRP proteins provide new insights in the search for targets and biomarkers needed for therapeutic strategies for PDAC treatment.

Lack of transient receptor potential ankyrin 1 (TRPA1) retards cutaneous wound healing in mice: A preliminary study

Wound healing is an important process in various diseases, and elucidating the underlying mechanism is essential for developing therapeutic strategies. We investigated whether the loss of transient receptor potential ankyrin 1 (TRPA1) affects the cutaneous wound healing process in mice. We assessed the formation of granulation tissue by myofibroblasts and macrophages, re-epithelialization, and related gene expression. TRPA1-null (KO) and wild-type (WT) C57BL/6 mice were used for establishing the wound model. Two round full-thickness excision wounds (diameter, 5.0 mm) were produced in the dorsal skin of mice under general anesthesia. After specific intervals, healing was evaluated using macroscopic observation, histology, immunohistochemistry, and real-time reverse transcription-polymerase chain reaction (RT-PCR). TRPA1 KO retarded the formation of granulation tissue and re-epithelialization in the healing of cutaneous wound. Furthermore, TRPA1 KO suppressed the appearance of myofibroblasts, macrophage infiltration, and mRNA expression of αSMA, F4/80, and Col-1α2. These findings indicate that TRPA1 is required for cutaneous wound healing in mice. The lack of TRPA1 retards macrophage infiltration and the subsequent fibrotic tissue formation, which might further impair the fibrogenic behavior of fibroblasts.

Evaluation of analgesic and anti-inflammatory activity of purine-2,6-dione-based TRPA1 antagonists with PDE4/7 inhibitory activity

BackgroundTo verify the validity of the proposed pain treatment approach, which is based on concomitant blocking of the Transient Receptor Potential Ankyrin 1 (TRPA1) channel and phosphodiesterases (PDEs) 4B/7A activity, we continued our pharmacological studies on 8-alkoxypurine-2,6-diones selected based on previous in vitro screening.MethodsDerivatives 17, 31, and 36 were pharmacologically evaluated in vivo using the formalin test and oxaliplatin-induced neuropathic pain: the von Frey and the cold plate tests, and in the carrageenan-induced edema model. Compound 36, which turned out to be the most promising, was further evaluated in the collagen-induced arthritis model. The pharmacokinetic parameters of this compound were also estimated.ResultsAll the tested compounds exhibited significant analgesic and anti-inflammatory activities. Compound 36 was additionally characterized by an antiarthritic effect and showed a favorable pharmacokinetic profile in rats.ConclusionThe compounds evaluated in this study represent a new class of derivatives with analgesic and anti-inflammatory activities that involve TRPA1 antagonism and PDE4/7 inhibition.Graphical abstract

Cannabidiol: Influence on B Cells, Peripheral Blood Mononuclear Cells, and Peripheral Blood Mononuclear Cell/Rheumatoid Arthritis Synovial Fibroblast Cocultures.

Background: Cannabidiol (CBD), one major nonintoxicating phytocannabinoid from Cannabis sativa demonstrated anti-inflammatory effects in animal models of several inflammatory conditions, including arthritis. However, it is still unknown which cell types mediate these anti-inflammatory effects of CBD, and, since CBD binds to a plethora of receptors and enzymes, it is complicated to pinpoint its mechanism of action. In this study, we elucidate the effects of CBD on B cells and peripheral blood mononuclear cells (PBMCs) in respect to survival, calcium mobilization, drug uptake, and cytokine (IL-6, IL-10, and TNF) and immunoglobulin production. Methods: Modulation of intracellular calcium and drug uptake in B cells was determined by using the fluorescent dyes Cal-520 and PoPo3, respectively. Cytokine and immunoglobulin production was evaluated by enzyme-linked immunosorbent assay. PBMC composition and B cell survival after CBD treatment was assessed by flow cytometry. Results: B cells express two major target receptors for CBD, TRPV2 (transient receptor potential vanilloid 2) and TRPA1 (transient receptor potential ankyrin 1), which are not regulated by B cell activation. CBD increased intracellular calcium levels in mouse and human B cells, which was accompanied by enhanced uptake of PoPo3. These effects were not dependent on transient receptor potential channel activation. CBD increased the number of early apoptotic B cells at the expense of viable cells and diminished interleukin (IL)-10 and tumor necrosis factor (TNF) production when activated T cell independently. In PBMCs, CBD increased IL-10 production when B cells were activated T cell dependent, while decreasing TNF levels when activated T cell independently. In PBMC/rheumatoid synovial fibroblast cocultures, CBD reduced IL-10 production when B cells were activated T cell independently. Immunoglobulin M production was augmented by CBD when B cells were activated with CpG. Conclusion: CBD is able to provide pro- and anti-inflammatory effects in isolated B cells and PBMCs. This is dependent on the activating stimulus (T cell dependent or independent) and concentration of CBD. Therefore, CBD might be used to dampen B cell activity in autoimmune conditions such as rheumatoid arthritis, in which B cells are activated by specific autoantigens.

TRP channels and monoterpenes: Past and current leads on analgesic properties.

The activation of the transient receptor potential (TRP) channels expressed by sensory neurons is essential to the transduction of thermal and mechanical sensory information. In the setting of chronic inflammatory conditions, the activation of the melastatin family member 8 (TRPM8), the TRP vanilloid 1 (TRPV1), and the TRP ankyrin 1 (TRPA1) is correlated with pain hypersensitivity reactions. Monoterpenes, among which pulegone and menthol, a major class of phytocompounds present in essential oils of medicinal plants, are known modulators of those TRP channels activity. In the present review, we correlate the monoterpene content of plants with their historical therapeutic properties. We then describe how monoterpenes exert their anti-inflammatory and antihyperalgesia effects through modulation of TRP channels activity. Finally, we discuss the importance and the potential of characterizing new plant extracts and reassessing studied plant extracts for the development of ethnopharmacology-based innovative treatments for chronic pain. This review suggests that monoterpene solutions, based on composition from traditional healing herbs, offer an interesting avenue for the development of new phytotherapeutic treatments to alleviate chronic inflammatory pain conditions.

TRPA1 modulation by Sigma-1 receptor prevents oxaliplatin-induced painful peripheral neuropathy.

Chemotherapy-induced peripheral neuropathy is a frequent, disabling side effect of anticancer drugs. Oxaliplatin, a platinum compound used in the treatment of advanced colorectal cancer, often leads to a form of chemotherapy-induced peripheral neuropathy characterized by mechanical and cold hypersensitivity. Current therapies for chemotherapy-induced peripheral neuropathy are ineffective, often leading to the cessation of treatment. Transient receptor potential ankyrin 1 (TRPA1) is a polymodal, non-selective cation-permeable channel expressed in nociceptors, activated by physical stimuli and cellular stress products. TRPA1 has been linked to the establishment of chemotherapy-induced peripheral neuropathy and other painful neuropathic conditions. Sigma-1 receptor is an endoplasmic reticulum chaperone known to modulate the function of many ion channels and receptors. Sigma-1 receptor antagonist, a highly selective antagonist of Sigma-1 receptor, has shown effectiveness in a phase II clinical trial for oxaliplatin chemotherapy-induced peripheral neuropathy. However, the mechanisms involved in the beneficial effects of Sigma-1 receptor antagonist are little understood. We combined biochemical and biophysical (i.e. intermolecular Förster resonance energy transfer) techniques to demonstrate the interaction between Sigma-1 receptor and human TRPA1. Pharmacological antagonism of Sigma-1R impaired the formation of this molecular complex and the trafficking of functional TRPA1 to the plasma membrane. Using patch-clamp electrophysiological recordings we found that antagonists of Sigma-1 receptor, including Sigma-1 receptor antagonist, exert a marked inhibition on plasma membrane expression and function of human TRPA1 channels. In TRPA1-expressing mouse sensory neurons, Sigma-1 receptor antagonists reduced inward currents and the firing of actions potentials in response to TRPA1 agonists. Finally, in a mouse experimental model of oxaliplatin neuropathy, systemic treatment with a Sigma-1 receptor antagonists prevented the development of painful symptoms by a mechanism involving TRPA1. In summary, the modulation of TRPA1 channels by Sigma-1 receptor antagonists suggests a new strategy for the prevention and treatment of chemotherapy-induced peripheral neuropathy and could inform the development of novel therapeutics for neuropathic pain.

2-hydroxyethyl methacrylate-derived reactive oxygen species stimulate ATP release via TRPA1 in human dental pulp cells

Extracellular ATP (adenosine triphosphate) and transient receptor potential ankyrin 1 (TRPA1) channels are involved in calcium signaling in odontoblasts and dental pain. The resin monomer 2-hydroxyethyl methacrylate (HEMA), used in dental restorative procedures, is related to apoptotic cell death via oxidative stress. Although the TRPA1 channel is highly sensitive to reactive oxygen species (ROS), the effect of HEMA-induced ROS on ATP release to the extracellular space and the TRPA1 channel has not been clarified in human dental pulp. In this study, we investigated the extracellular ATP signaling and TRPA1 activation by HEMA-derived ROS in immortalized human dental pulp cells (hDPSC-K4DT). Among the ROS-sensitive TRP channels, TRPA1 expression was highest in undifferentiated hDPSC-K4DT cells, and its expression levels were further enhanced by osteogenic differentiation. In differentiated hDPSC-K4DT cells, 30 mM HEMA increased intracellular ROS production and ATP release, although 3 mM HEMA had no effect. Pretreatment with the free radical scavenger PBN (N-tert-butyl-α-phenylnitrone) or TRPA1 antagonist HC-030031 suppressed HEMA-induced responses. These results suggest that ROS production induced by a higher dose of HEMA activates the TRPA1 channel in human dental pulp cells, leading to ATP release. These findings may contribute to the understanding of the molecular and cellular pathogenesis of tertiary dentin formation and pain in response to dental biomaterials.

Transient receptor potential Ankyrin 1: structure, function and ligands

Introduction: Transient receptor potential ankyrin 1 (TRPA1) is a protein expressed in many living organisms. During the study of TRPA1, its unique biological role as a universal and polymodal sensor of various altering agents was found. The aim of this study is to search and generalize information about structural features and molecular determinants, mechanisms of activation, action and modulation of TRPA1 as a universal pain and inflammation sensor, as well as the nature of activators and antagonists of this target and their therapeutic potential.
 Materials and methods: This article presents an overview of the results of scientific research of TRPA1, its modulators, as well as an overview of their pharmacological potential over the period from the discovery of these channels to the present, with an emphasis on the last decade.
 Results and discussion: The main collected data on expression, structural features and molecular determinants, mecha­nisms of activation and action of TRPA1 indicate its role as a universal and labile element of the primary response of the body to adverse exogenous and endogenous factors. Regardless of the nature of the stimulus, hyperstimulation of TRPA1 channels can lead to such phenomena as pain, inflammation, itching, edema and other manifestations of alteration, and therefore TRPA1 blockade can be used in the treatment of various diseases accompanied by these pathological conditions. Currently, TRPA1 antagonists are being actively searched for and studied, as evidenced by a high patent activity over the past 14 years; however, the molecular mechanisms of action and pharmacological properties of TRPA1 blockers remain understudied.
 Conclusion: Acquire of new information about TRPA1 will help in the development of its modulators, which can be­come promising analgesics, anti-inflammatory drugs, bronchodilators, and agents for the treatment of cardiovascular diseases of new generations.

The role of free fatty acid receptor pathways in a selective regulation of TRPA1 and TRPV1 by resolvins in primary sensory neurons.

Transient receptor potential ankyrin 1 and vanilloid 1 (TRPA1 and TRPV1, respectively) channels contribute to inflammatory and neuropathic pain, indicating that their pharmacological inhibition could be a novel strategy for treating painful diseases. However, the mechanisms of TRPA1/V1 channel modulation have been mostly characterized to be upregulation and sensitization via variety of exogenous stimuli, endogenous inflammatory mediators, and metabolites of oxidative stress. Here we used calcium imaging of dorsal root ganglion neurons to identify an inhibitor signaling pathway for TRPA1 and TRPV1 regulated by resolvins (RvD1 and RvE1), which are endogenous anti‐inflammatory lipid mediators. TRPA1 and TRPV1 channel activations were evoked by the TRPA1 agonist allyl isothiocyanate and the TRPV1 agonist capsaicin. Our results show that RvD1‐induced selective inhibition of TRPA1 activity was mediated by free fatty acid receptor 4 (FFAR4)‐protein kinase C (PKC) signaling. Experiments assessing RvE1‐induced TRPV1 inhibition showed that RvE1 actions required both FFAR1 and FFAR4. Combined stimulation of FFAR1/FFAR4 or FFAR1/PKC mimicked TRPV1 inhibition by RvE1, and these effects were blocked by a protein kinase D (PKD) inhibitor, implying that PKD is an effector of the FFAR/PKC signaling axis in RvE1‐induced TRPV1 inhibition. Despite selective inhibition of TRPV1 in the nanomolar range of RvE1, higher concentrations of RvE1 also inhibited TRPA1, possibly through PKC. Collectively, our findings reveal FFAR1 and FFAR4 as key signaling pathways mediating the selective targeting of resolvins to regulate TRPA1 and TRPV1, elucidating endogenous analgesic mechanisms that could be exploited as potential therapeutic targets.

Role of TRPA1/TRPV1 in acute ozone exposure induced murine model of airway inflammation and bronchial hyperresponsiveness.

BackgroundTransient receptor potential (TRP) ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) mediate the development of lung injury and inflammation. This study investigated the role and mechanism of the TRPA1/TRPV1 pathway in airway inflammation and bronchial hyperresponsiveness (BHR) induced by acute ozone exposure.MethodsC57BL/6 mice (8–10 weeks) were intraperitoneally injected with phosphate buffered saline (PBS), A967079 (TRPA1 inhibitor) or AMG9810 (TRPV1 inhibitor) 1 h before or after ozone exposure (2.5 ppm, 3 h). BHR, cell counts in bronchoalveolar lavage (BAL) fluid, oxidative stress biomarkers, inflammatory cytokines, TRPA1 and TPRV1 protein levels, mitochondrial dynamics- and mitophagy-related protein levels, and activities of mitochondrial respiratory chain (MRC) in lung were measured.ResultsThe preventive treatment effect was similar to the therapeutic treatment effect. Both A967079 and AMG9810 intervention suppressed BHR, inflammatory cytokines, total BAL fluid cells, malondialdehyde (MDA) levels and inflammatory cytokines mRNA including Substance P (SP), Keratinocyte-Derived Chemokine (KC), interleukin-18 (IL-18) and chemokine (C-X-C motif) ligand 8 (CXCL8) expression, and enhanced reduced glutathione (GSH)/oxidized glutathione (GSSG) levels compared with ozone-exposed mice. A967079 and AMG9810 intervention inhibited dynamin-related protein (DRP1), mitochondrial fission factor (MFF), Parkinson protein 2 E3 ubiquitin protein ligase (PARK2) and Sequestosome 1 (SQSTM1)/p62 expression, increased Optic atrophy 1 (OPA1), mitofusin 2 (MFN2) and PTEN-induced putative kinase 1 (PINK1) expression, and up-regulated the activities of MRC complex III and V in lung tissue.ConclusionsThe results show that both TRPA1 and TRPV1 pathways are involved in acute ozone exposure-induced airway inflammation and BHR and influence oxidative stress, mitochondrial quality control and MRC activity, which could be a potential target for clinical therapy of respiratory diseases.

Regulation of thermoregulatory behavior by commensal bacteria in Drosophila.

Commensal bacteria affect many aspects of host physiology. In this study, we focused on the role of commensal bacteria in the thermoregulatory behavior of Drosophila melanogaster. We demonstrated that the elimination of commensal bacteria caused an increase in the preferred temperature of Drosophila third-instar larvae without affecting the activity of transient receptor potential ankyrin 1 (TRPA1)-expressing thermosensitive neurons. We isolated eight bacterial strains from the gut and culture medium of conventionally reared larvae and found that the preferred temperature of the larvae was decreased by mono-association with Lactobacillus plantarum or Corynebacterium nuruki. Mono-association with these bacteria did not affect the indices of energy metabolism such as ATP and glucose levels of larvae, which are closely linked to thermoregulation in animals. Thus, we show a novel role for commensal bacteria in host thermoregulation and identify two bacterial species that affect thermoregulatory behavior in Drosophila.

Enhanced production of IL-2 from anti-CD3 antibody-stimulated mouse spleen cells by artepillin C, a major component of Brazilian green propolis

ObjectivesIn this report, we attempt to clarify the immune modulatory effects of Brazilian green propolis (BGP) and its major component, artepillin C, on the cytokine production of anti-CD3 antibody-stimulated mouse spleen cells. We also estimate the physiological mechanism affecting artepillin C's upon the cells. MethodsMale C3H/HeN mouse spleen cells stimulated by antiCD3 monoclonal antibody were co-cultured with BGP, artepillin C, and HC030031, a transient receptor potential ankyrin 1 (TRPA1) Ca2+ channel antagonist. The synthesis of interferon (IFN)-γ, interleukin (IL)-6, IL-17, IL-4, IL-10, and IL-2 was assayed by enzyme-linked immunoassay. The expression of IL-2 mRNA and the protein product were examined by reverse transcription-quantitative polymerase chain reaction and Western blot analyses, respectively. ResultsThe production of IL-2 was markedly enhanced, while that of IL-4 and IL-10 was not significantly affected; by contrast, the production of IFN-γ, IL-6, and IL-17 was significantly reduced in the antibody-stimulated spleen cells treated with BGP at a non-cytostatic concentration. These effects were reproduced in the cells treated with artepillin C. The expression of IL-2 mRNA was unaffected; however, that of the protein was significantly enhanced in the artepillin C-treated cells compared to untreated control cells. The enhancement of protein expression and the production of IL-2 by artepillin C was significantly alleviated by adding HC030031. ConclusionsArtepillin C is an important regulator of cytokine synthesis from activated spleen cells. The agent specifically augmented the expression of IL-2 via the Ca2+-permeable cation channel, TRPA1, at least in part, at the translational or secretion levels.