Transient Receptor Potential Vanilloid Type Research Articles

Shaoyao Gancao Decoction Ameliorates Paclitaxel-Induced Peripheral Neuropathy via Suppressing TRPV1 and TLR4 Signaling Expression in Rats.

PurposePaclitaxel-induced peripheral neuropathy (PIPN) is increasingly becoming one of the most widespread adverse effects in the treatment of cancer patients, and further precipitate neuroinflammation in the nervous system. Interestingly, Shaoyao Gancao Decoction (SGD), a traditional Chinese analgesic prescription, has emerged as a primary adjuvant to chemotherapy in relieving side effects, especially in the case of PIPN. However, the underlying mechanism of SGD functioning in PIPN remains elusive. Accordingly, the current study set out to explore the potential axis implicated in the functioning of SGD in PIPN.MethodsFirst, network pharmacology was adopted to predict the role of the transient receptor potential vanilloid type 1 (TRPV1) protein in treating PIPN with SGD. Subsequently, the effects of SGD treatment on mechanical allodynia and thermal hyperalgesia were evaluated in rat PIPN models. Based on the bioinformatics information and current literature, paclitaxel activates toll-like receptor 4 (TLR4) induces the sensitization of TRPV1 mechanistically. Thereafter, TLR4-myeloid-differentiation response gene 88 (MyD88) signaling and TRPV1 expression patterns in dorsal root ganglias (DRGs) were measured by means of Western blotting, qPCR and immunofluorescence.ResultsInitial bioinformatics reared a total of 105 bioactive compounds and 1075 target genes from SGD. In addition, 40 target genes intersected with PIPN were considered as potential therapeutic genes. Based on the network analysis, SGD was found to exert its analgesic effect by reducing the expression of TRPV1. Further experimentation validated that SGD exerted an analgesic effect on thermal hyperalgesia in PIPN models, such that this protective effect was associated with the suppression of TRPV1 and TLR4-MyD88 Signaling over-expression.ConclusionCollectively, our findings indicated that SGD ameliorates PIPN by inhibiting the over-expression of TLR4-MyD88 Signaling and TRPV1, and further highlights the use of SGD as a potential alternative treatment for PIPN.

Systemic application of the transient receptor potential vanilloid-type 4 antagonist GSK2193874 induces tail vasodilation in a mouse model of thermoregulation.

In humans, skin is a primary thermoregulatory organ, with vasodilation leading to rapid body cooling, whereas in Rodentia the tail performs an analogous function. Many thermodetection mechanisms are likely to be involved including transient receptor potential vanilloid-type 4 (TRPV4), an ion channel with thermosensitive properties. Previous studies have shown that TRPV4 is a vasodilator by local action in blood vessels, so here, we investigated whether constitutive TRPV4 activity affects Mus muscularis tail vascular tone and thermoregulation. We measured tail blood flow by pressure plethysmography in lightly sedated M. muscularis (CD1 strain) at a range of ambient temperatures, with and without intraperitoneal administration of the blood–brain barrier crossing TRPV4 antagonist GSK2193874. We also measured heart rate (HR) and blood pressure. As expected for a thermoregulatory organ, we found that tail blood flow increased with temperature. However, unexpectedly, we found that GSK2193874 increased tail blood flow at all temperatures, and we observed changes in HR variability. Since local TRPV4 activation causes vasodilation that would increase tail blood flow, these data suggest that increases in tail blood flow resulting from the TRPV4 antagonist may arise from a site other than the blood vessels themselves, perhaps in central cardiovascular control centres.

LncRNA MEG3-TRPV1 signaling regulates chronic inflammatory pain in rats.

Osteoarthritis (OA) is a common osteoarthropathy with chronic inflammatory pain as the core symptom in middle-aged and elderly people. LncRNA MEG3 (Maternally expressed gene 3) is involved in the development of OA via regulation of angiogenesis, which causes the activation and overexpression of transient receptor potential vanilloid type-1 (TRPV1). In this study, we investigated the mechanism of MEG3-TRPV1 signaling in chronic inflammatory pain (CIP) of rat model. Chronic inflammatory pain was modeled using subcutaneous microinjection of complete Freund's adjuvant (CFA) into the left hind paw of rats. We showed that TRPV1 mRNA and protein were significantly increased, while MEG3 mRNA was significantly decreased, in the DRG and SDH of CFA-induced rats. In addition, intrathecal injection of MEG3-overexpressing lentivirus significantly downregulated TRPV1 expression and alleviated chronic inflammatory pain in CFA-induced rats. Treatment with a TRPV1 antagonist also significantly relieved chronic inflammatory pain in CFA-induced rats. In general, our results reveal that MEG3 alleviates chronic inflammatory pain by downregulating TRPV1 expression. These findings may provide new therapeutic targets in the treatment of patients with OA.

Repeated Morphine Administration Increases TRPV1 mRNA Expression and Autoradiographic Binding at Supraspinal Sites in the Pain Pathway

Repeated morphine administration induces tolerance to its analgesic effects. A previous study reported that repeated morphine treatment activates transient receptor potential vanilloid type 1 (TRPV1) expression in the sciatic nerve, dorsal root ganglion, and spinal cord, contributing to morphine tolerance. In the present study, we analyzed TRPV1 expression and binding sites in supraspinal pain pathways in morphine-tolerant mice. The TRPV1 mRNA levels and binding sites were remarkably increased in the cortex and thalamus of these animals. Our data provide additional insights into the effects of morphine on TRPV1 in the brain and suggest that changes in the expression of, and binding to TRPV1 in the brain are involved in morphine tolerance.

A breakdown in microglial metabolic reprogramming causes internalization dysfunction of α-synuclein in a mouse model of Parkinson’s disease

BackgroundThe α-synuclein released by neurons activates microglia, which then engulfs α-synuclein for degradation via autophagy. Reactive microglia are a major pathological feature of Parkinson’s disease (PD), although the exact role of microglia in the pathogenesis of PD remains unclear. Transient receptor potential vanilloid type 1 (TRPV1) channels are nonselective cation channel protein that have been proposed as neuroprotective targets in neurodegenerative diseases.MethodsUsing metabolic profiling, microglia energy metabolism was measured including oxidative phosphorylation and aerobic glycolysis. The mRFP-GFP-tagged LC3 reporter was introduced to characterize the role of TRPV1 in microglial autophagy. α-synuclein preformed fibril (PFF) TRPV1flox/flox; Cx3cr1Cre mouse model of sporadic PD were employed to study the capacity of TRPV1 activation to attenuate neurodegeneration process.ResultsWe found that acute exposure to PFF caused microglial activation as a result of metabolic reprogramming from oxidative phosphorylation to aerobic glycolysis via the AKT–mTOR–HIF-1α pathway. Activated microglia eventually reached a state of chronic PFF-tolerance, accompanied by broad defects in energy metabolism. We showed that metabolic boosting by treatment with the TRPV1 agonist capsaicin rescued metabolic impairments in PFF-tolerant microglia and also defects in mitophagy caused by disruption of the AKT–mTOR–HIF-1α pathway. Capsaicin attenuated phosphorylation of α-synuclein in primary neurons by boosting phagocytosis in PFF-tolerant microglia in vitro. Finally, we found that behavioral deficits and loss of dopaminergic neurons were accelerated in the PFF TRPV1flox/flox; Cx3cr1Cre mouse model of sporadic PD. We identified defects in energy metabolism, mitophagy and phagocytosis of PFF in microglia from the substantia nigra pars compacta of TRPV1flox/flox; Cx3cr1Cre mice.ConclusionThe findings suggest that modulating microglial metabolism might be a new therapeutic strategy for PD.

Effects of transient receptor potential vanilloid type 4-specific activator on human vascular endothelial cell functions and blood supply of rat perforator flap and its mechanism

Effects of transient receptor potential vanilloid type 4-specific activator on human vascular endothelial cell functions and blood supply of rat perforator flap and its mechanism

Statins Inhibit the Gliosis of MIO-M1, a Müller Glial Cell Line Induced by TRPV4 Activation.

We characterized Müller cell gliosis induced by the activation of transient receptor potential vanilloid-type 4 (TRPV4) and assessed whether statins could modulate the gliosis. The human Müller cell line, MIO-M1, was used to analyze the gliosis caused by glaucomatous stimulation. To induce Müller gliosis in MIO-M1 cells, GSK101 was used to activate TRPV4, and Müller gliosis was evaluated by analyzing vimentin, nestin, and glial fibrillary acidic protein (GFAP) expression. The expression level of TNF-α was determined by ELISA. To evaluate the GSK101 activation of the NF-κB pathway, p65 phosphorylation was measured by Western blotting, and the nuclear translocation of p65 and IκBα phosphorylation were assessed by immunostaining. To assess the effect of statins on MIO-M1 gliosis, cells were pretreated for 24 h with statins before GSK101 treatment. Vimentin, nestin, and GFAP expression were upregulated by GSK101, while statins effectively inhibited them. The expression of TNF-α was increased by GSK101. The phosphorylation and nuclear translocation of p65 and IκBα phosphorylation, which occurs prior to p65 activation, were induced. Statins suppressed the GSK101-mediated phosphorylation of IκBα and p65 translocation. Statins can mitigate gliosis in the human Müller cell line. Because TRPV4 activation in Müller cells reflects glaucoma pathophysiology, statins may have the potential to prevent RGC death.

Renal chemosensitive and mechanosensitive afferent responses are preserved in TRPV1 knockout rats

The transient receptor potential vanilloid type‐1 (TRPV1) channel is expressed in renal sensory nerves, and intrarenal administration of the TRPV1 agonist capsaicin increases renal afferent nerve activity (ARNA). Nonselective denervation of renal sensory nerves using high concentration capsaicin reduces arterial blood pressure (ABP) in experimental models of hypertension. Pharmacological blockade of TRPV1 using renal pelvic infusion of capsazepine attenuates ARNA responses to capsaicin, CGRP, and elevated pelvic pressure. Thus, TRPV1 channels mediate activation of renal sensory nerves.To test this hypothesis, we generated a novel TRPV1 knockout rat (TRPV1‐/‐) using CRISPR/Cas9 to produce a 26bp deletion in exon 3. Multifiber ARNA responses to chemical (bradykinin and capsaicin) and mechanical (elevated renal pelvic pressure) stimuli were compared in Inactin‐anesthetized male and female wild‐type and TRPV1‐/‐ littermates (250‐400g). There were no significant differences in baseline mean ABP between wild‐type and TRPV1‐/‐ rats (122±2 mmHg vs 122±3 mmHg, respectively; p=0.48, n=8‐10), or baseline ARNA between wild‐type and TRPV1‐/‐ rats (14±3 Hz vs 18±5 Hz, respectively; p=0.24, n=8‐10).Intrarenal artery infusion of capsaicin (0.1–10μM, 50μL per 15s) significantly increased ipsilateral ARNA in wild‐type but not TRPV1‐/‐ rats (Δ discharge 65±14 Hz vs 9±3 Hz at 10μM, respectively; p<0.05, n=7). As a second chemosensitive stimulus, intrarenal artery infusion of bradykinin (0.1–10μM, 50μL per 15s) produced significant increases in ARNA in ­both wild‐type and TRPV1‐/‐ rats that were not significantly different between groups (Δ discharge of 10μM: 52±11 Hz vs 76±21 Hz, respectively; p=0.33, n=7). Elevated renal pelvic pressure (0–20mmHg; 30s) significantly increased ARNA in both wild‐type and TRPV1‐/‐ rats; however, ARNA responses were significantly smaller in wild‐type versus TRPV1‐/‐ rats (Δ discharge with 20mmHg: 17±3 Hz versus 29±6 Hz, respectively; p=0.03, n=8‐9).The preservation of ARNA responses in TRPV1‐/‐ rats contradicts prior studies using pharmacological TRPV1 antagonists. A final set of experiments tested whether intrapelvic capsazepine infusion (200μM, 200μl per 3 min) attenuates ARNA responses to elevated pelvic pressure (20mmHg) in both wild‐type and Trpv1‐/‐ rats. Interestingly, pelvic administration of capsazepine attenuated mechanosensitive ARNA responses in both wildtype (saline: 31±3 Hz vs capsazepine: 8±1 Hz; n=3) and TRPV1‐/‐ (saline: 20±7 Hz vs capsazepine: 6±1 Hz; n=3) rats thereby suggesting a TRPV1‐independent action of capsazepine.In conclusion, TRPV1 channels are dispensable for the activation of chemo‐ and mechanosensitive renal sensory nerves.

Transient receptor potential vanilloid type-1 regulates periodontal disease damage via the PI3K/AKT signaling pathway.

Objective(s):This study aimed to investigate the function of transient receptor potential vanilloid 1 (TRPV1) in regulating periodontal lesions. In addition, we explored the underlying mechanism of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway.Materials and Methods:Lipopolysaccharide (LPS) stimulation of human periodontal ligament cells (HPDLCs) was used to construct a periodontitis cell model, and experimental periodontitis (EP) rats were established by ligation. The mechanism by which TRPV1 regulates periodontitis was further verified by injecting the TRPV1 agonist capsaicin (CPS) and antagonist capsazepine (CPZ) into the gingiva of rats; the alveolar bone losses in each group were measured by stereomicroscopy. Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting (WB) were used to research the expression of TRPV1 and proinflammatory cytokines, and WB was performed to test the phosphorylation of PI3K and AKT.Results: In vitro experiments showed that LPS induced the upregulation of TRPV1 and proinflammatory cytokines and promoted the phosphorylation of PI3K and AKT proteins in HPDLCs, which was consistent with their expression in the rat periodontitis model. Moreover, in vivo studies indicated that CPZ had anti-inflammatory effects through the PI3K/AKT pathway and inhibited bone loss induced by periodontal ligation in rats, while CPS had the opposite effect.Conclusion:TRPV1 was involved in the process of alveolar bone defects and the inflammatory response in rats with periodontitis induced by ligation. Its mechanism might be related to the phosphorylation of related proteins in the PI3K/AKT signaling pathway.

Network Pharmacology Analysis of Hewei Jiangni Granule for Gastroesophageal Reflux Disease and Experimental Verification of Its Anti-Neurogenic Inflammation Mechanism.

PurposeProton pump inhibitors, as the first-line drugs for treating gastroesophageal reflux disease (GERD), are unable to completely relieve patients’ symptoms and patients are prone to recurrence after prolonged drug withdrawal. Thus, it is crucial to find herbal medicines as a complementary and alternative treatment. Hewei Jiangni granule (HWJNG) is a classical Chinese medicinal formula with clinical therapeutic effects on GERD, but its pharmacological mechanism of action remains unclear. This study aimed to explore and then verify the pharmacological mechanisms of HWJNG in GERD therapy.MethodsA network pharmacology approach was applied to explore and then verify the pharmacological mechanisms of HWJNG in GERD therapy. The active ingredients of HWJNG, as well as therapeutic targets of GERD were acquired from specialized databases. The “herb-ingredient-gene-target” network for HWJNG in GERD treatment was built. The protein–protein interaction (PPI) network was constructed to screen the core coincident targets. Then, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed. The core targets and signaling pathways associated with the anti-neurogenic inflammatory effect were partially verified via experiments in vivo at molecular level.ResultsIn total, 179 chemical ingredients in HWJNG and 298 intersection targets between GERD and HWJNG were selected from databases. A large proportion of core targets and top signaling pathways were involved in neurogenic inflammation. HWJNG significantly alleviated pathological injuries of esophagus and reversed dilated intracellular spaces. Additionally, HWJNG markedly inhibited the excessive release of inflammatory cytokines such as interleukin (IL)-1β, IL-6, tumor necrosis factor receptor (TNF-a), as well as regulated stimulation sensors including transient receptor potential vanilloid type 1 (TRPV1) and its related neuroinflammatory mediators in GERD mice.ConclusionHWJNG is a promising therapeutic strategy for GERD treatment via regulation of multiple targets and pathways, its effects in alleviating neurogenic inflammation are especially acknowledged.

Effects of CB2 and TRPV1 Stimulation on Osteoclast Overactivity Induced by Iron in Pediatric Inflammatory Bowel Disease.

BackgroundThe reduction of bone mineral density and osteoporosis have high impacts on the health of patients with inflammatory bowel diseases (IBD). We have previously shown that a dysregulated iron metabolism occurs in IBD and leads to a decrease in circulating iron concentration and excessive intracellular sequestration of iron. Studies suggest that iron overload significantly affects the bone, accelerating osteoclast (OC) differentiation and activation, promoting bone resorption. Moreover, we demonstrated that iron overload causes OC overactivity. The cannabinoid receptor type 2 (CB2) and the transient receptor potential vanilloid type-1 (TRPV1) are potential therapeutic targets for bone diseases. The aim of this study was to evaluate the roles of CB2 and TRPV1 receptors and of iron in the development of osteoporosis in pediatric IBD.MethodsWe differentiated OCs from peripheral blood mononuclear cells of patients with IBD and healthy donors and evaluated CB2 and TRPV1 receptor expression; OC activity, and iron metabolism by Western blot, TRAP assays, bone resorption assays, and iron assays. Moreover, we analyzed the effects of the pharmacological modulation of CB2 and TRPV1 receptors on OC activity and on the iron metabolism.ResultsWe confirmed the well-known roles of CB2 and TRPV1 receptors in bone metabolism and suggested that their stimulation can reduce the OC overactivity induced by iron, providing new insights into the pathogenesis of pediatric IBD-related bone resorption.ConclusionsStimulation of CB2 and TRPV1 could reduce IBD-related osteoporosis due to their direct effects on OC activity and to modulating the iron metabolism.

Ishophloroglucin A, Isolated from Ishige okamurae, Alleviates Dexamethasone-Induced Muscle Atrophy through Muscle Protein Metabolism In Vivo.

The in vitro capacity of Ishige okamurae extract (IO) to improve impaired muscle function has been previously examined. However, the mechanism underlying IO-mediated muscle protein metabolism and the role of its component, Ishophloroglucin A (IPA), in mice with dexamethasone (Dexa)-induced muscle atrophy remains unknown. In the present study, we evaluated the effect of IO and IPA supplementation on Dexa-induced muscle atrophy by assessing muscle protein metabolism in gastrocnemius and soleus muscles of mice. IO and IPA supplementation improved the Dexa-induced decrease in muscle weight and width, leading to enhanced grip strength. In addition, IO and IPA supplementation regulated impaired protein synthesis (PI3K and Akt) or degradation (muscle-specific ubiquitin ligase muscle RING finger and atrogin-1) by modulating mRNA levels in gastrocnemius and soleus muscles. Additionally, IO and IPA upregulated mRNA levels associated with muscle growth activation (transient receptor potential vanilloid type 4 and adenosine A1 receptor) or inhibition (myostatin and sirtuin 1) in gastrocnemius and soleus muscle tissues of Dexa-induced mice. Collectively, these results suggest that IO and IO-derived IPA can regulate muscle growth through muscle protein metabolism in Dexa-induced muscle atrophy.

Hydrogel cultures reveal Transient Receptor Potential Vanilloid 4 regulation of myofibroblast activation and proliferation in valvular interstitial cells.

As aortic valve stenosis develops, valve tissue becomes stiffer. In response to this change in environmental mechanical stiffness, valvular interstitial cells (VICs) activate into myofibroblasts. We aimed to investigate the role of mechanosensitive calcium channel Transient Receptor Potential Vanilloid type 4 (TRPV4) in stiffness induced myofibroblast activation. We verified TRPV4 functionality in VICs using live calcium imaging during application of small molecule modulators of TRPV4 activity. We designed hydrogel biomaterials that mimic mechanical features of healthy or diseased valve tissue microenvironments, respectively, to investigate the role of TRPV4 in myofibroblast activation and proliferation. Our results show that TRPV4 regulates VIC proliferation in a microenvironment stiffness-independent manner. While there was a trend toward inhibiting myofibroblast activation on soft microenvironments during TRPV4 inhibition, we observed near complete deactivation of myofibroblasts on stiff microenvironments. We further identified Yes-activated protein (YAP) as a downstream target for TRPV4 activity on stiff microenvironments. Mechanosensitive TRPV4 channels regulate VIC myofibroblast activation, whereas proliferation regulation is independent of the microenvironmental stiffness. Collectively, the data suggests differential regulation of stiffness-induced proliferation and myofibroblast activation. Our data further suggest a regulatory role for TRPV4 regarding YAP nuclear localization. TRPV4 is an important regulator for VIC myofibroblast activation, which is linked to the initiation of valve fibrosis. Although more validation studies are necessary, we suggest TRPV4 as a promising pharmaceutical target to slow aortic valve stenosis progression.

Membrane Interactivity of Capsaicin Antagonized by Capsazepine.

Although the pharmacological activity of capsaicin has been explained by its specific binding to transient receptor potential vanilloid type 1, the amphiphilic structure of capsaicin may enable it to act on lipid bilayers. From a mechanistic point of view, we investigated whether capsaicin and its antagonist capsazepine interact with biomimetic membranes, and how capsazepine influences the membrane effect of capsaicin. Liposomal phospholipid membranes and neuro-mimetic membranes were prepared with 1,2-dipalmitoylphosphatidylcholine and with 1-palmitoyl-2-oleoylphosphatidylcholine and sphingomyelin plus cholesterol, respectively. These membrane preparations were subjected to reactions with capsaicin and capsazepine at 0.5–250 μM, followed by measuring fluorescence polarization to determine the membrane interactivity to modify the fluidity of membranes. Both compounds acted on 1,2-dipalmitoylphosphatidylcholine bilayers and changed membrane fluidity. Capsaicin concentration-dependently interacted with neuro-mimetic membranes to increase their fluidity at low micromolar concentrations, whereas capsazepine inversely decreased the membrane fluidity. When used in combination, capsazepine inhibited the effect of capsaicin on neuro-mimetic membranes. In addition to the direct action on transmembrane ion channels, capsaicin and capsazepine share membrane interactivity, but capsazepine is likely to competitively antagonize capsaicin’s interaction with neuro-mimetic membranes at pharmacokinetically-relevant concentrations. The structure-specific membrane interactivity may be partly responsible for the analgesic effect of capsaicin.

Efficacy of Endoscopic Radiofrequency Ablation for Treatment of Reflux Hypersensitivity: A Study Based on Rome IV Criteria.

Objective Effective therapies for reflux hypersensitivity are lacking. Endoscopic radiofrequency ablation may reduce the sensitivity of the distal esophagus through direct interference with nociceptors or vagal afferent fibers and thus may be useful in reflux hypersensitivity. The aim of this study is to assess the effectiveness and possible mechanisms of endoscopic radiofrequency ablation in reflux hypersensitivity patients. Methods Patients with reflux hypersensitivity who fulfilled the Rome IV criteria and who wished to receive further treatment were recruited. Endoscopic radiofrequency ablation was delivered to the gastroesophageal junction. Data were collected by questionnaire using a 6-point Likert scale. The primary outcome measure was effect on symptoms including heartburn, regurgitation, and chest pain. The secondary outcomes were degree of satisfaction, medication use, acid exposure time (AET), low esophageal sphincter (LES) pressure, and total reflux episodes. We also assessed positive cell density of transient receptor potential vanilloid type 1 receptor (TRPV1) and calcitonin gene-related peptide (CGRP), both of which are biomarkers of afferent fibers, in biopsies obtained from esophageal mucosa 0.5 cm-1 cm above the Z line. These scales will be administered at baseline, 3-month follow-up, 6-month follow-up, and 12-month follow-up. Results A total of 22 reflux hypersensitivity patients were enrolled (14 males, median age 50.0 years). A significant improvement in symptom scores (heartburn, regurgitation, and chest pain) was noted at 3 months, 6 months, and 12 months (P < 0.001). Satisfaction with life increased to 72.7% (16/22), 72.7% (16/22), and 68.2% (15/22) at 3, 6, and 12 mo, respectively, compared with baseline (P < 0.001). Nineteen patients reduced their medication use after treatment. Of these, 22.7% (5/22), 31.8% (7/22), and 40.9% (9/22) subjects stopped medication use at 3 mo, 6 mo, and 12 mo, respectively. No statistical differences were noted in AET, LES pressure, or total reflux episodes from preoperation to 12 mo postoperation. After treatment, the positive cell density of both TRPV1 and CGRP decreased significantly; however, only TRPV1 had a positive correlation with heartburn (r = 0.51, P = 0.03) and chest pain (r = 0.77, P < 0.01). Conclusion Endoscopic radiofrequency ablation was an effective and safe therapeutic option in reflux hypersensitivity patients. Further studies with large sample size are required to validate the role of radiofrequency in reflux hypersensitivity.

Inflammatory and contractile profile in LPS-challenged equine isolated bronchi: Evidence for IL-6 as a potential target against AHR in equine asthma

BackgroundAirway inflammation and airway hyperresponsiveness (AHR) are pivotal characteristics of equine asthma. Lipopolysaccharide (LPS) may have a central role in modulating airway inflammation and dysfunction. Therefore, the aim of this study was to match the inflammatory and contractile profile in LPS-challenged equine isolated bronchi to identify molecular targets potentially suitable to counteract AHR in asthmatic horses. MethodsEquine isolated bronchi were incubated overnight with LPS (0.1–100 ng/ml). The contractile response to electrical field stimulation (EFS) and the levels of cytokines, chemokines, and neurokinin A (NKA) were quantified. The role of capsaicin sensitive-sensory nerves, neurokinin-2 (NK2) receptor, transient receptor potential vanilloid type 1 receptors (TRPV1), and epithelium were also investigated. ResultsLPS 1 ng/ml elicited AHR to EFS (+238.17 ± 25.20% P < 0.001 vs. control). LPS significantly (P < 0.05 vs. control) increased the levels of IL-4 (+36.08 ± 1.62%), IL-5 (+38.60 ± 3.58%), IL-6 (+33.79 ± 2.59%), IL-13 (+40.91 ± 1.93%), IL-1β (+1650.16 ± 71.16%), IL-33 (+88.14 ± 8.93%), TGF-β (22.29 ± 1.03%), TNF-α (+56.13 ± 4.61%), CXCL-8 (+98.49 ± 17.70%), EOTAXIN (+32.26 ± 2.27%), MCP-1 (+49.63 ± 4.59%), RANTES (+36.38 ± 2.24%), and NKA (+112.81 ± 6.42%). Capsaicin sensitive-sensory nerves, NK2 receptor, and TRPV1 were generally involved in the LPS-mediated inflammation. Epithelium removal modulated the release of IL-1β, IL-33, and TGF-β. Only the levels of IL-6 fitted with AHR to a wide range of EFS frequencies, an effect significantly (P < 0.05) inhibited by anti-IL-6 antibody; exogenous IL-6 induced significant (P < 0.05) AHR to EFS similar to that elicited by LPS. ConclusionTargeting IL-6 with specific antibody may represent an effective strategy to treat equine asthma, especially in those animals suffering from severe forms of this disease.

Capsaicin Ameliorates the Loosening of Mitochondria-Associated Endoplasmic Reticulum Membranes and Improves Cognitive Function in Rats With Chronic Cerebral Hypoperfusion.

Based on accumulating evidence, vascular factors contribute to cognitive decline and dementia. Mitochondrial dysfunction is the core pathophysiological mechanism. Mitochondria-associated endoplasmic reticulum membranes (MAMs) are subcellular structures that physically and biologically connect mitochondria with the endoplasmic reticulum (ER) and regulate multiple functions ranging from calcium transfer to mitochondrial dynamics and bioenergetics. MAMs dysfunction has been speculated to be a key factor contributing to the pathogenesis of cognitive disorders and a new therapeutic target. However, the alteration of MAMs in vascular cognitive impairment remains to be revealed. Capsaicin, a specific agonist known to activated the transient receptor potential vanilloid type 1 (TRPV1), is involved in hippocampal synaptic plasticity and memory, but the detailed mechanism is still unclear. In this study, chronic cerebral hypoperfusion (CCH) model rats were created by bilateral common carotid artery occlusion (BCCAO), which is a widely used model to study vascular dementia. We observed that CCH rats showed obvious cognitive deficits, and ER-mitochondria contacts were loosener with lower expression of mitofusin2 (MFN2), a key protein connecting MAMs, in the hippocampal CA1 region, compared to the sham group. After capsaicin treatment for 12 weeks, we found that cognitive deficits induced by CCH were significantly alleviated and loosened ER-mitochondrial interactions were obviously improved. In conclusion, the findings of this study highlight that MAMs may contribute to the pathogenesis of cognitive impairment induced by CCH, and our new evidence that capsaicin improves cognitive function highlights a novel opportunity for drug discovery.

Capsaicin Attenuates Arterial Calcification Through Promoting SIRT6-Mediated Deacetylation and Degradation of Hif1α (Hypoxic-Inducible Factor-1 Alpha).

Sustained Hif1α (hypoxic-inducible factor-1 alpha) accumulation plays a central role in osteogenic transdifferentiation and subsequent calcification. Capsaicin, the potent agonist of TRPV1 (transient receptor potential vanilloid type 1), was found to mitigate hypoxic-related injury and reverse phenotypic switch of vascular smooth muscle cells. However, its role in arterial calcification and the underlying mechanisms remain unexplored. We used data from Multi-Ethnic Study of Atherosclerosis to examine the association of coronary artery calcification and chili consumption. Chronic kidney disease mice and high phosphate-induced vascular smooth muscle cells calcification models were established to investigate the anticalcification effect of capsaicin, evaluated by calcium deposition and changes in phenotype markers. Chili consumption was negatively correlated with coronary artery calcification and conferred a smaller progression burden during follow-up. Capsaicin reduced calcium deposition and osteogenic transdifferentiation both in vivo and in vitro. Using siTRPV1 (small interfering RNA and the antagonist of TRPV1), the anticalcification effect of capsaicin was abrogated. Hif1α was increased in phosphate-treated vascular smooth muscle cells and its degradation was accelerated by capsaicin. Retaining Hif1α stability using cobalt chloride (CoCl2) or MG132 abolished the protective effect of capsaicin. We further identified an increased expression of SIRT6 (Sirtuin 6) in response to capsaicin and confirmed the physical interaction between SIRT6 and Hif1α. Acetylated Hif1α was decreased, whereas hydroxylated Hif1α was increased under capsaicin treatment. Using immunohistochemistry analysis, we observed increased SIRT6 and reduced Hif1α in both SIRT6 transgenic and capsaicin-treated chronic kidney disease mice. Capsaicin facilitates deacetylation and degradation of Hif1α by upregulating SIRT6, which inhibits osteogenic transdifferentiation and protects against arterial calcification. These data highlight a promising therapeutic target for the management of arterial calcification.

Disruption of Hyaluronic Acid in Skeletal Muscle Induces Decreased Voluntary Activity via Chemosensitive Muscle Afferent Sensitization in Male Mice.

PEGPH20, a human recombinant hyaluronidase, has been proposed as a coadjutant to pancreatic cancer chemotherapy. In early trials, patients reported increased widespread muscle pain as the main adverse reaction to PEGPH20. To understand how PEGPH20 caused musculoskeletal pain, we systemically administered PEGPH20 to male mice and measured voluntary wheel activity and pain-related behaviors. These were paired with ex vivo electrophysiology of primary sensory neurons, whole DRG real-time PCR, and immunohistochemistry of hindpaw muscle. PEGPH20 induced significantly lower wheel running, compared with vehicle-treated animals, and decreased mechanical withdrawal thresholds 5 d after PEGPH20 injections. Chemo-sensory muscle afferents showed increased responses to noxious chemical stimulation of their receptive fields (RFs) in the PEGPH20-treated group. This was correlated with upregulation of the NGF receptor TrkA, the transient receptor potential vanilloid type 1 (TRPV1) channel and ATP-sensitive channel P2X3 in the DRG. Immunohistochemistry of hindpaw muscles revealed damage to the muscle architecture and extensive infiltration of the tissue by cells of the myelomonocytic lineage 3 d after PEGPH20 injection. Peripheral macrophage ablation in macrophage Fas-induced apoptosis (MaFIA) mice, however, did not prevent the decreased voluntary activity and instead caused even lower levels of running. These results suggest that disruption of hyaluronic acid (HA) within the muscle extracellular matrix (ECM) sensitizes chemo-nociceptive muscle afferents possibly leading to altered pain-like behaviors. Ablation experiments suggest macrophages are necessary for adequate recovery of voluntary activity after HA disruption. These data support a role for HA and macrophages in tissue integrity and muscle pain development in patients taking PEGPH20.

Targeting CB2 and TRPV1: Computational Approaches for the Identification of Dual Modulators.

Both metabotropic (CBRs) and ionotropic cannabinoid receptors (ICRs) have implications in a range of neurological disorders. The metabotropic canonical CBRs CB1 and CB2 are highly implicated in these pathological events. However, selective targeting at CB2 versus CB1 offers optimized pharmacology due to the absence of psychoactive outcomes. The ICR transient receptor potential vanilloid type 1 (TRPV1) has also been reported to play a role in CNS disorders. Thus, activation of both targets, CB2 and TRPV1, offers a promising polypharmacological strategy for the treatment of neurological events including analgesia and neuroprotection. This brief research report aims to identify chemotypes with a potential dual CB2/TRPV1 profile. For this purpose, we have rationalized key structural features for activation and performed virtual screening at both targets using curated chemical libraries.