Curcumin Produces an Antihyperalgesic Effect via Antagonism of TRPV1

Curcumin has diverse therapeutic effects, such as anti-inflammatory, anti-oxidant, anti-cancer, and antimicrobial activities. The vanilloid moiety of curcumin is considered important for activation of the transient receptor potential vanilloid 1 (TRPV1), which plays an important role in nociception. However, very little is known about the effects of curcumin on nociception. In the present study, we investigated whether the anti-nociceptive effects of curcumin are mediated via TRPV1 by using nociceptive behavioral studies and in vitro whole-cell patch-clamp recordings in the trigeminal system. Subcutaneous injection of capsaicin in the vibrissa pad area of rats induced thermal hyperalgesia. Intraperitoneally administered curcumin blocked capsaicin-induced thermal hyperalgesia in a dose-dependent manner. Whereas curcumin reduced capsaicin-induced currents in a dose-dependent manner in both trigeminal ganglion neurons and TRPV1-expressing HEK 293 cells, curcumin did not affect heat-induced TRPV1 currents. Taken together, our results indicate that curcumin blocks capsaicin-induced TRPV1 activation and thereby inhibits TRPV1-mediated pain hypersensitivity.

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Mechanisms underlying the antifibrotic properties of noninhibitory PAI-1 (PAI-1R) in experimental nephritis

AJP Renal Physiology ◽

10.1152/ajprenal.00024.2009 ◽

2009 ◽

Vol 297 (4) ◽

pp. F1045-F1054 ◽

Cited By ~ 16

Author(s):

Yufeng Huang ◽

Wayne A. Border ◽

Daniel A. Lawrence ◽

Nancy A. Noble

Keyword(s):

Half Life ◽

Stable Form ◽

Therapeutic Effects ◽

Dependent Manner ◽

Therapeutic Action ◽

Protease Inhibition ◽

Ecm Degradation ◽

Dose Dependent ◽

Pai 1

Administration of a mutant, noninhibitory PAI-1 (PAI-1R), reduces disease in experimental glomerulonephritis. Here we investigated the importance of vitronectin (Vn) binding, PAI-1 stability and protease binding in this therapeutic effect using a panel of PAI-1 mutants differing in half-life, protease binding, and Vn binding. PAI-1R binds Vn normally but does not inhibit proteases. PAI-1AK has a complete defect in Vn binding but retains full inhibitory activity, with a short half-life similar to wild-type (wt)-PAI-1. Mutant 14-lb is identical to wt-PAI-1 but with a longer half-life. PAI-1K has defective Vn binding, inhibits proteases normally, and has a long half-life. In vitro wt-PAI-1 dramatically inhibited degradation of mesangial cell ECM while the AK mutant had much less effect. Mutants 14-1b and PAI-1K, like wt-PAI-1, inhibited matrix degradation but PAI-1R failed to reverse this inhibition although PAI-1R reversed the wt-PAI-1-induced inhibition of ECM degradation in a plasmin-, time-, and dose-dependent manner. Thus the ability of PAI-1 to inhibit ECM degradation is dependent both on its antiproteinase activity and on maintaining an active conformation achieved either by Vn binding or mutation to a stable form. Administration of these PAI-1 mutants to nephritic rats confirmed the in vitro data; only PAI-1R showed therapeutic effects. PAI-1K did not bind to nephritic kidney, indicating that Vn binding is essential to the therapeutic action of PAI-1R. The ability of PAI-1R to remain bound to Vn even in a high-protease environment is very likely the key to its therapeutic efficacy. Furthermore, because both PAI-1R and 14-1b bound to the nephritic kidney in the same pattern and differ only in their ability to bind proteases, lack of protease inhibition is also keyed to PAI-1R's therapeutic action.

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TRPV4 Plays a Role in Matrix Stiffness-Induced Macrophage Polarization

Frontiers in Immunology ◽

10.3389/fimmu.2020.570195 ◽

2020 ◽

Vol 11 ◽

Author(s):

Bidisha Dutta ◽

Rishov Goswami ◽

Shaik O. Rahaman

Keyword(s):

Transient Receptor Potential ◽

Macrophage Polarization ◽

Transient Receptor Potential Vanilloid ◽

Polarization Spectrum ◽

Dependent Manner ◽

Matrix Stiffness ◽

Soft Matrix ◽

Genetic Ablation ◽

M1 Macrophage

Phenotypic polarization of macrophages is deemed essential in innate immunity and various pathophysiological conditions. We have now determined key aspects of the molecular mechanism by which mechanical cues regulate macrophage polarization. We show that Transient Receptor Potential Vanilloid 4 (TRPV4), a mechanosensitive ion channel, mediates substrate stiffness-induced macrophage polarization. Using atomic force microscopy, we showed that genetic ablation of TRPV4 function abrogated fibrosis-induced matrix stiffness generation in skin tissues. We have determined that stiffer skin tissue promotes the M1 macrophage subtype in a TRPV4-dependent manner; soft tissue does not. These findings were further validated by our in vitro results which showed that stiff matrix (50 kPa) alone increased expression of macrophage M1 markers in a TRPV4-dependent manner, and this response was further augmented by the addition of soluble factors; neither of which occurred with soft matrix (1 kPa). A direct requirement for TRPV4 in M1 macrophage polarization spectrum in response to increased stiffness was evident from results of gain-of-function assays, where reintroduction of TRPV4 significantly upregulated the expression of M1 markers in TRPV4 KO macrophages. Together, these data provide new insights regarding the role of TRPV4 in matrix stiffness-induced macrophage polarization spectrum that may be explored in tissue engineering and regenerative medicine and targeted therapeutics.

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Pirt Together with TRPV1 Is Involved in the Regulation of Neuropathic Pain

Neural Plasticity ◽

10.1155/2018/4861491 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 5

Author(s):

Changming Wang ◽

Leying Gu ◽

Yonglan Ruan ◽

Tana Gegen ◽

Lei Yu ◽

...

Keyword(s):

Neuropathic Pain ◽

Transient Receptor Potential ◽

Life Quality ◽

Thermal Hyperalgesia ◽

In Vitro Study ◽

Receptor Potential ◽

Transient Receptor Potential Vanilloid ◽

Cci Model ◽

Transient Receptor

Neuropathic pain is a chronic pain and reduces the life quality of patients substantially. Transient receptor potential vanilloid channel 1 (TRPV1), a nonselective cation channel, has been shown to play a crucial role in neuropathic pain. Although TRPV1 plays an important role in neuropathic pain, the mechanism of how TRPV1 was regulated in neuropathic pain remains unclear. Pirt is a membrane protein and binds to TRPV1 to enhance its activity. It was suggested that Pirt should also be involved in neuropathic pain. In this study, we investigated the role of Pirt in neuropathic pain (CCI model); the results show that mechanical allodynia and thermal hyperalgesia were alleviated in Pirt−/− mice in CCI models. TRPV1 expression was increased by immunofluorescence and real-time PCR experiments. The increase in TRPV1 expression was less in Pirt knockout mice in CCI models. Moreover, the number of capsaicin-responding neurons and the magnitude of evoked calcium response were attenuated in DRG neurons from Pirt−/− mice in CCI models. Finally, we found that the pain behavior attenuated in dysfunction of both Pirt and TRPV1 was much stronger than in dysfunction of Pirt or TRPV1 only in a CCI model in vitro study. Taken together, Pirt together with TRPV1 is involved in CCI-induced neuropathic pain.

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Spinal PAR2 Activation Contributes to Hypersensitivity Induced by Peripheral Inflammation in Rats

International Journal of Molecular Sciences ◽

10.3390/ijms22030991 ◽

2021 ◽

Vol 22 (3) ◽

pp. 991

Author(s):

Petra Mrozkova ◽

Diana Spicarova ◽

Jiri Palecek

Keyword(s):

Synaptic Transmission ◽

Dorsal Horn ◽

Dorsal Root ◽

Transient Receptor Potential ◽

Thermal Hyperalgesia ◽

Dorsal Root Ganglion Neurons ◽

Peripheral Inflammation ◽

Transient Receptor Potential Vanilloid ◽

Behavioral Experiments ◽

Ganglion Neurons

The mechanisms of inflammatory pain need to be identified in order to find new superior treatments. Protease-activated receptors 2 (PAR2) and transient receptor potential vanilloid 1 (TRPV1) are highly co-expressed in dorsal root ganglion neurons and implicated in pain development. Here, we examined the role of spinal PAR2 in hyperalgesia and the modulation of synaptic transmission in carrageenan-induced peripheral inflammation, using intrathecal (i.t.) treatment in the behavioral experiments and recordings of spontaneous, miniature and dorsal root stimulation-evoked excitatory postsynaptic currents (sEPSCs, mEPSCs and eEPSCs) in spinal cord slices. Intrathecal PAR2-activating peptide (AP) administration aggravated the carrageenan-induced thermal hyperalgesia, and this was prevented by a TRPV1 antagonist (SB 366791) and staurosporine i.t. pretreatment. Additionally, the frequency of the mEPSC and sEPSC and the amplitude of the eEPSC recorded from the superficial dorsal horn neurons were enhanced after acute PAR2 AP application, while prevented with SB 366791 or staurosporine pretreatment. PAR2 antagonist application reduced the thermal hyperalgesia and decreased the frequency of mEPSC and sEPSC and the amplitude of eEPSC. Our findings highlight the contribution of spinal PAR2 activation to carrageenan-induced hyperalgesia and the importance of dorsal horn PAR2 and TRPV1 receptor interactions in the modulation of nociceptive synaptic transmission.

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The mechanisms of protease-activated receptor 2 in mediating pain behaviors through nonselective cation channel signaling

10.21203/rs.2.19972/v1 ◽

2020 ◽

Author(s):

Yaping Yue ◽

Na Wang ◽

Yanming Lau ◽

Yiran Fu ◽

Hao Li ◽

...

Keyword(s):

Signaling Pathway ◽

Mechanical Allodynia ◽

Transient Receptor Potential ◽

Thermal Hyperalgesia ◽

Receptor Potential ◽

Transient Receptor Potential Vanilloid ◽

Drg Neurons ◽

Pain Behaviors ◽

Transient Receptor

Abstract Background: Activation of purinergic receptor P2X ligand-gated ion channel 3 (P2X3), transient receptor potential vanilloid type 1 (TRPV1), and transient receptor potential ankyrin 1 (TRPA1) by their specific ligands is a major mechanism contributing to magnified pain responses. The relationship between these nonselective cation channels and proteinase-activated receptor 2 (PAR2) activation mediated pain is still to be clarified.Methods: In this study, both in vitro model of dorsal root ganglion (DRG) neurons with PAR2 agonist SL-NH2 challenge and SL-NH2-induced pain rat model were used to approach these questions. The expression of P2X3, TRPV1, and TRPA1 in DRG neurons was investigated by quantitative real-time RT-PCR, Western blot, and immunofluorescence. The involvement of the PLCβ3/PKCε signaling pathway was also determined. The behavior test for mechanical allodynia and thermal hyperalgesia was performed. Results: SL-NH2 induced upregulation of P2X3, TRPV1, and TRPA1 through phosphorylation of phospholipase Cβ3 (PLCβ3) and protein kinase Cε (PKCε) signaling pathway in DRG neurons in vitro and in vivo. SL-NH2 also elevated the proportion of P2X3-, TRPV1-, and TRPA1-expressing neurons. The upregulation of P2X3, TRPV1, and TRPA1 and phosphorylation of PLCβ3 and PKCε in DRG neurons was paralleled with mechanical allodynia and thermal hyperalgesia behaviors in rats. Conclusions: The data of the present study imply that SL-NH2 as a noxious stimulus activates PAR2 which induces TRPV1, TRPA1, and P2X3 upregulation through PLCβ3/PKCε signaling pathway, thereby decreasing activation thresholds and increasing excitability, resulting in sustained nociceptive activity in DRG neurons, and then causing mechanical allodynia and thermal hyperalgesia behaviors. These data expanded our knowledge about PAR2-mediated pain sensitivity and its relationship with TRPV1, TRPA1, and P2X3 and provided new opportunities on management of pain behaviors.

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Lipid Nanoparticle Inclusion Prevents Capsaicin-Induced TRPV1 Defunctionalization

Pharmaceutics ◽

10.3390/pharmaceutics12040339 ◽

2020 ◽

Vol 12 (4) ◽

pp. 339

Author(s):

Carmelo Puglia ◽

Debora Santonocito ◽

Angela Bonaccorso ◽

Teresa Musumeci ◽

Barbara Ruozi ◽

...

Keyword(s):

Transient Receptor Potential ◽

Prolonged Exposure ◽

Thermal Hyperalgesia ◽

Receptor Potential ◽

Transient Receptor Potential Vanilloid ◽

Spontaneous Pain ◽

Plantar Surface ◽

Transient Receptor ◽

Chronic Pain Conditions

Background: Capsaicin (CPS) is a highly selective agonist of the transient receptor potential vanilloid type 1 (TRPV1) with a nanomolar affinity. High doses or prolonged exposure to CPS induces TRPV1 defunctionalization and, although this effect is currently used for the treatment of thermal hyperalgesia in chronic pain conditions, it is responsible of detrimental effects, such as denervation of sensory fibers. The aim of the present study was to formulate CPS loaded lipid nanocarriers (CPS-LN) in order to optimize CPS release, thus preventing TRPV1 internalization and degradation. Methods: CPS-LNs were formulated and characterized by in vitro studies. The activation of TRPV1 receptors after CPS-LN administration was evaluated by measuring spontaneous pain that was induced by local injection into the plantar surface of the mouse hind-paw. Moreover, the expression of TRPV1 in the skin was evaluated by western blot analysis in CPS-LN injected mice and then compared to a standard CPS solution (CPS-STD). Results: CPS inclusion in LN induced a lower pain response when compared to CPS-STD; further, it prevented TRPV1 down-regulation in the skin, while CPS-STD induced a significant reduction of TRPV1 expression. Conclusions: Drug encapsulation in lipid nanoparticles produced an optimization of CPS release, thus reducing mice pain behavior and avoiding the effects that are caused by TRPV1 defunctionalization related to a prolonged activation of this receptor.

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CDK5 inhibits the clathrin-dependent internalization of TRPV1 by phosphorylating the clathrin adaptor protein AP2μ2

Science Signaling ◽

10.1126/scisignal.aaw2040 ◽

2019 ◽

Vol 12 (585) ◽

pp. eaaw2040 ◽

Cited By ~ 1

Author(s):

Jiao Liu ◽

Junxia Du ◽

Yun Wang

Keyword(s):

Drug Targets ◽

Transient Receptor Potential ◽

Phosphorylation Site ◽

Thermal Hyperalgesia ◽

Adaptor Protein ◽

Receptor Potential ◽

Dorsal Root Ganglion Neurons ◽

Transient Receptor Potential Vanilloid ◽

Transient Receptor ◽

Ganglion Neurons

Transient receptor potential vanilloid 1 (TRPV1), a nonselective, ligand-gated cation channel, responds to multiple noxious stimuli and is targeted by many kinases that influence its trafficking and activity. Studies on the internalization of TRPV1 have mainly focused on that induced by capsaicin or other agonists. Here, we report that constitutive internalization of TRPV1 occurred in a manner dependent on clathrin, dynamin, and adaptor protein complex 2 (AP2). The μ2 subunit of AP2 (AP2μ2) interacted directly with TRPV1 and was required for its constitutive internalization. Cyclin-dependent kinase 5 (CDK5) phosphorylated AP2μ2 at Ser45, which reduced the interaction between TRPV1 and AP2μ2, leading to decreased TRPV1 internalization. Intrathecal delivery of a cell-penetrating fusion peptide corresponding to the Cdk5 phosphorylation site in AP2μ2, which competed with AP2μ2 for phosphorylation by Cdk5, increased the abundance of TRPV1 on the surface of dorsal root ganglion neurons and reduced complete Freund’s adjuvant (CFA)–induced inflammatory thermal hyperalgesia in rats. In addition to describing a mechanism of TRPV1 constitutive internalization and its inhibition by CDK5, these findings demonstrate that CDK5 promotes inflammatory thermal hyperalgesia by reducing TRPV1 internalization, providing previously unidentified insights into the search for drug targets to treat pain.

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Attenuation of TRPV1 and TRPV4 Expression and Function in Mouse Inflammatory Pain Models Using Electroacupuncture

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2012/636848 ◽

2012 ◽

Vol 2012 ◽

pp. 1-12 ◽

Cited By ~ 12

Author(s):

Wei-Hsin Chen ◽

Jason T. C. Tzen ◽

Ching Liang Hsieh ◽

Yung Hsiang Chen ◽

Tzu-Jou Lin ◽

...

Keyword(s):

Inflammatory Pain ◽

Transient Receptor Potential ◽

Thermal Hyperalgesia ◽

Receptor Potential ◽

Dorsal Root Ganglion Neurons ◽

Transient Receptor Potential Vanilloid ◽

Pain Mechanisms ◽

Electrophysiological Properties ◽

Pain Models ◽

Ganglion Neurons

Although pain is a major human affliction, our understanding of pain mechanisms is limited. TRPV1 (transient receptor potential vanilloid subtype 1) and TRPV4 are two crucial receptors involved in inflammatory pain, but their roles in EA- (electroacupuncture-) mediated analgesia are unknown. We injected mice with carrageenan (carra) or a complete Freund’s adjuvant (CFA) to model inflammatory pain and investigated the analgesic effect of EA using animal behavior tests, immunostaining, Western blotting, and a whole-cell recording technique. The inflammatory pain model mice developed both mechanical and thermal hyperalgesia. Notably, EA at the ST36 acupoint reversed these phenomena, indicating its curative effect in inflammatory pain. The protein levels of TRPV1 and TRPV4 in DRG (dorsal root ganglion) neurons were both increased at day 4 after the initiation of inflammatory pain and were attenuated by EA, as demonstrated by immunostaining and Western blot analysis. We verified DRG electrophysiological properties to confirm that EA ameliorated peripheral nerve hyperexcitation. Our results indicated that the AP (action potential) threshold, rise time, and fall time, and the percentage and amplitude of TRPV1 and TRPV4 were altered by EA, indicating that EA has an antinociceptive role in inflammatory pain. Our results demonstrate a novel role for EA in regulating TRPV1 and TRPV4 protein expression and nerve excitation in mouse inflammatory pain models.

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2-Aminoethoxydiphenyl borate stimulates pulmonary C neurons via the activation of TRPV channels

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00439.2004 ◽

2005 ◽

Vol 288 (5) ◽

pp. L932-L941 ◽

Cited By ~ 30

Author(s):

Qihai Gu ◽

Ruei-Lung Lin ◽

Hong-Zhen Hu ◽

Michael X. Zhu ◽

Lu-Yuan Lee

Keyword(s):

Transient Receptor Potential ◽

Ruthenium Red ◽

Transient Receptor Potential Vanilloid ◽

Dependent Manner ◽

C Fibers ◽

Trpv Channels ◽

C Fiber ◽

Aminoethoxydiphenyl Borate

This study was carried out to determine the effect of 2-aminoethoxydiphenyl borate (2-APB), a common activator of transient receptor potential vanilloid (TRPV) type 1, 2, and 3 channels, on cardiorespiratory reflexes, pulmonary C fiber afferents, and isolated pulmonary capsaicin-sensitive neurons. In anesthetized, spontaneously breathing rats, intravenous bolus injection of 2-APB elicited the pulmonary chemoreflex responses, characterized by apnea, bradycardia, and hypotension. After perineural treatment of both cervical vagi with capsaicin to block the conduction of C fibers, 2-APB no longer evoked any of these reflex responses. In open-chest and artificially ventilated rats, 2-APB evoked an abrupt and intense discharge in vagal pulmonary C fibers in a dose-dependent manner. The stimulation of C fibers by 2-APB was attenuated but not abolished by capsazepine, a selective antagonist of the TRPV1, which completely blocked the response to capsaicin in these C fiber afferents. In isolated pulmonary capsaicin-sensitive neurons, 2-APB concentration dependently evoked an inward current that was partially inhibited by capsazepine but almost completely abolished by ruthenium red, an effective blocker of all TRPV channels. In conclusion, 2-APB evokes a consistent and distinct stimulatory effect on pulmonary C fibers in vivo and on isolated pulmonary capsaicin-sensitive neurons in vitro. These results establish the functional evidence demonstrating that TRPV1, V2, and V3 channels are expressed on these sensory neurons and their terminals.

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Evaluation of Anti-Mycobacterial Compounds in a Silkworm Infection Model with Mycobacteroides abscessus

Molecules ◽

10.3390/molecules25214971 ◽

2020 ◽

Vol 25 (21) ◽

pp. 4971

Author(s):

Kanji Hosoda ◽

Nobuhiro Koyama ◽

Hiroshi Hamamoto ◽

Akiho Yagi ◽

Ryuji Uchida ◽

...

Keyword(s):

Antimicrobial Agents ◽

In Vitro Assay ◽

Infection Model ◽

Therapeutic Effects ◽

Dependent Manner ◽

Vitro Assay ◽

Infection Assay ◽

Microbial Products ◽

Dose Dependent

Among four mycobacteria, Mycobacterium avium, M. intracellulare, M. bovis BCG and Mycobacteroides (My.) abscessus, we established a silkworm infection assay with My. abscessus. When silkworms (fifth-instar larvae, n = 5) were infected through the hemolymph with My. abscessus (7.5 × 107 CFU/larva) and bred at 37 °C, they all died around 40 h after injection. Under the conditions, clarithromycin and amikacin, clinically used antimicrobial agents, exhibited therapeutic effects in a dose-dependent manner. Furthermore, five kinds of microbial compounds, lariatin A, nosiheptide, ohmyungsamycins A and B, quinomycin and steffimycin, screened in an in vitro assay to observe anti-My. abscessus activity from 400 microbial products were evaluated in this silkworm infection assay. Lariatin A and nosiheptide exhibited therapeutic efficacy. The silkworm infection model with My. abscessus is useful to screen for therapeutically effective anti-My. abscessus antibiotics.

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