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Chronic constriction injury-induced microRNA-146a-5p alleviates neuropathic pain through suppression of IRAK1/TRAF6 signaling pathway.

ABSTRACT: BACKGROUND:microRNA-146a-5p (miRNA-146a-5p) is a key molecule in the negative regulation pathway of TLRs and IL-1 receptor (TIR) signaling. Our recent study demonstrated that MyD88-dependent signaling pathway of TIR in the dorsal root ganglion (DRG) and spinal dorsal horn (SDH) plays a role in peripheral nerve injury-induced neuropathic pain. However, it was not clear whether and how miRNA-146a-5p regulates the TIR pathway of DRG and SDH in the development of neuropathic pain. METHODS:The sciatic nerve chronic constriction injury (CCI) model of rat was used to induce chronic neuropathic pain. The levels and cellular distribution of miRNA-146a-5p were detected with quantitative real-time PCR (qPCR) and fluorescent in situ hybridization (FISH). The RNA level, protein level, and cellular distribution of IRAK1 and TRAF6 that is targeted by miRNA-146a-5p were detected with qPCR, western blot, and immunofluorescent. The pain-related behavioral effect of miRNA-146a-5p was accessed after intrathecal administration. Mechanical stimuli and radiant heat were used to evaluate mechanical allodynia and thermal hyperalgesia. RESULTS:We found that the level of miRNA-146a-5p significantly increased in L4-L6 DRGs and SDH after CCI surgery; meanwhile, the protein level of IRAK1 and TRAF6 in DRGs was significantly increased after CCI. Intrathecal injection of miR146a-5p agomir or miRNA-146a-5p antagomir regulates miRNA-146a-5p level of L4-L6 DRGs and SDH. We found that intrathecal injection of miR146a-5p agomir can alleviate mechanical and thermal hyperalgesia in CCI rats and reverse the upregulation of IRAK1 and TRAF6 of L4-L6 DRGs and SDH induced by CCI. We furthermore found that intrathecal injection of miRNA-146a-5p antagomir can exacerbate the mechanical and thermal pain-related behavior of CCI rats and meanwhile increase IRAK1 and TRAF6 of L4-L6 DRGs and SDH expression even further. CONCLUSIONS:miRNA-146a-5p of DRG and SDH can modulate the development of CCI-induced neuropathic pain through inhibition of IRAK1 and TRAF6 in the TIR signaling pathway. Hence, miRNA-146a-5p may serve as a potential therapeutic target for neuropathic pain.

SUBMITTER: Wang Z

PROVIDER: S-EPMC5994250 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Chronic constriction injury-induced microRNA-146a-5p alleviates neuropathic pain through suppression of IRAK1/TRAF6 signaling pathway.

Wang Zhiyao Z Liu Fan F Wei Min M Qiu Yue Y Ma Chao C Shen Le L Huang Yuguang Y

Journal of neuroinflammation 20180609 1

<h4>Background</h4>microRNA-146a-5p (miRNA-146a-5p) is a key molecule in the negative regulation pathway of TLRs and IL-1 receptor (TIR) signaling. Our recent study demonstrated that MyD88-dependent signaling pathway of TIR in the dorsal root ganglion (DRG) and spinal dorsal horn (SDH) plays a role in peripheral nerve injury-induced neuropathic pain. However, it was not clear whether and how miRNA-146a-5p regulates the TIR pathway of DRG and SDH in the development of neuropathic pain.<h4>Methods ...[more]

PMID: 29885668

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Project description:BACKGROUND:Pulsed radiofrequency (PRF) is a minimally invasive interventional technique that provides a novel and effective treatment strategy for neuropathic pain (NP). PRF is advantageous because it does not damage nerves and avoids sensory loss after treatment. At present, animal studies have demonstrated that PRF is safe and effective for relieving the NP associated with sciatic nerve damage in rats with chronic constriction injury (CCI). However, the mechanism through which this effect occurs is unknown. An increasing body of evidence shows that the expression of the P2X ligand-gated ion channel 3 (P2X3) receptor is closely related to NP; this study was to investigate whether the expression of this receptor is involved in NP relief due to PRF. METHODS:A total of 36 healthy adult male Sprague-Dawley (SD) rats were randomly divided into three groups: Sham group, CCI group, and PRF group. The right sciatic nerve was ligated in CCI group and PRF group to establish a CCI model; the right sciatic nerve was separated but not ligated in Sham group. On day 14 after the operation, PRF was administered to the ligated sciatic nerve in PRF group (42°C, 45 V, 2 min). A non-live electrode was placed at the exposed sciatic nerve for the rats in Sham and CCI groups. The hindpaw withdrawal threshold (HWT) and thermal withdrawal latency (TWL) were measured at the right hindpaw at different time points before and after PRF or sham therapy. On day 28 after treatment, the dorsal root ganglion (DRG) and spinal dorsal horn of the right L4-6 were harvested from each group to determine the mRNA and protein levels of the P2X3 receptor. RESULTS:On day 28 after PRF treatment, the HWT (8.33?±?0.67?g vs. 3.62?±?0.48?g) and TWL (25.42?±?1.90?s vs. 15.10?±?1.71?s) were significantly higher in PRF group as compared to CCI group (P?<?0.05). The mRNA expression of the P2X3 receptor in the DRG in PRF group was 23.7% lower than that in CCI group (P?<?0.05), in the spinal dorsal horns in PRF group was 22.7% lower than that in CCI group (P?<?0.05). The protein expression of the P2X3 receptor in the DRG in PRF group was 27.8% lower than that in CCI group (P?<?0.05), in the spinal dorsal horns in PRF group was 35.6% lower than that in CCI group (P?<?0.05). CONCLUSION:PRF possibly reduces NP in CCI rats by inhibiting the expression of the P2X3 receptor in the L4-6 DRG and spinal dorsal horns.

Project description:BackgroundChronic inflammatory pain significantly reduces the quality of life and lacks effective interventions. In recent years, human umbilical cord mesenchymal stem cells (huc-MSCs)-derived exosomes have been used to relieve neuropathic pain and other inflammatory diseases as a promising cell-free therapeutic strategy. However, the therapeutic value of huc-MSCs-derived exosomes in complete Freund's adjuvant (CFA)-induced inflammatory pain remains to be confirmed. In this study, we investigated the therapeutic effect and related mechanisms of huc-MSCs-derived exosomes in a chronic inflammatory pain model.MethodsC57BL/6J male mice were used to establish a CFA-induced inflammatory pain model, and huc-MSCs-derived exosomes were intrathecally injected for 4 consecutive days. BV2 microglia cells were stimulated with lipopolysaccharide (LPS) plus adenosine triphosphate (ATP) to investigate the effect of huc-MSCs-derived exosomes on pyroptosis and autophagy. Bioinformatic analysis and rescue experiments were used to demonstrate the role of miR-146a-5p/ TRAF6 in regulating pyroptosis and autophagy. Western blotting, RT-qPCR, small interfering RNA and Yo-Pro-1 dye staining were performed to investigate the related mechanisms.ResultsHuc-MSCs-derived exosomes alleviated mechanical allodynia and thermal hyperalgesia in CFA-induced inflammatory pain. Furthermore, huc-MSCs-derived exosomes attenuated neuroinflammation by increasing the expression of autophagy-related proteins (LC3-II and beclin1) and inhibiting the activation of NLRP3 inflammasomes in the spinal cord dorsal horn. In vitro, NLRP3 inflammasome components (NLRP3, caspase1-p20, ASC) and gasdermin D (GSDMD-F, GSDMD-N) were inhibited in BV2 cells pretreated with huc-MSCs-derived exosomes. Western blot and Yo-Pro-1 dye staining demonstrated that 3-MA, an autophagy inhibitor, weakened the protective effect of huc-MSCs-derived exosomes on BV2 cell pyroptosis. Importantly, huc-MSCs-derived exosomes transfected with miR-146a-5p mimic promoted autophagy and inhibited BV2 cell pyroptosis. TRAF6, as a target gene of miR-146a-5p, was knocked down via small-interfering RNA, which increased pyroptosis and inhibited autophagy.ConclusionHuc-MSCs-derived exosomes attenuated inflammatory pain via miR-146a-5p/TRAF6, which increased the level of autophagy and inhibited pyroptosis.

Project description:BACKGROUND:Anti-nerve growth factor (NGF) monoclonal antibodies (anti-NGF mAbs) have been reported to significantly attenuate pain, but the mechanism involved has not been fully elucidated, and the serious adverse events associated with mAbs seriously limit their clinical use. This study further investigated the mechanism by which peripheral NGF is involved in neuropathic pain and found safe, natural compounds that target NGF to attenuate neuropathic pain. METHODS:Nociception was assessed by the Von Frey hair and Hargreaves' methods. Western-blotting, qPCR and immunofluorescence were used to detect the cell signaling pathway. RAW264.7 macrophages and RSC96 Schwann cells were cultured for in vitro evaluation. RESULTS:Intraplantar administration of anti-NGF mAbs suppressed the expression of phosphorylated transforming growth factor-?-activated kinase 1 (TAK1) in the dorsal root ganglion (DRG) and sciatic nerve. Intraplantar administration of a TAK1 inhibitor attenuated CCI-induced neuropathic pain and suppressed the expression of phosphorylated mitogen-activated protein kinases (MAPKs) in the DRG and sciatic nerve. Perisciatic nerve administration of levo-corydalmine (l-CDL) on the operated side obviously attenuated CCI-induced neuropathic pain and suppressed the expression of mNGF and proNGF. In addition, l-CDL-induced antinociception was reversed by intraplantar administration of NGF. Further results indicated that l-CDL-induced suppression of phosphorylated TAK1, MAPKs, and p65 and expression of the proinflammatory cytokines TNF-? and IL-1? in the DRG and sciatic nerve were all abolished by NGF. In addition, in vitro experiments indicated that l-CDL suppressed the secretion of NGF and proNGF in RAW264.7 macrophages and RSC96 Schwann cells, which was abolished by AP-1 and CREB agonists, respectively. CONCLUSIONS:This study showed NGF inhibition suppressed TAK1 in the periphery to attenuate CCI-induced neuropathic pain through inhibition of downstream MAPK and p65 signaling. The natural compound l-CDL inhibited NGF secretion by macrophages and Schwann cells and downstream TAK1-MAPK/NF-?B signaling in the periphery to attenuate CCI-induced neuropathic pain. Video abstract Proposed mechanisms underlying the effect of l-CDL in periphery of CCI rats. In CCI rats, macropahages and Schwann cells could secret NGF to act on the receptors in the periphery to activate TAK1-MAPK/NF-?B axis and promote the release of proinflammatory cytokines, including TNF-? and IL-1? to promote neuropathic pain. l-CDL decreased the secretion of NGF through inhibiting AP-1 and CREB respectively in RAW264.7 and RSC96 Schwann cells to attenuate CCI-induced neuropathic pain by inhibiting the TAK1-p38 MAPK/NF-?B signaling pathway.

Dataset Information

Chronic constriction injury-induced microRNA-146a-5p alleviates neuropathic pain through suppression of IRAK1/TRAF6 signaling pathway.

Publications

Chronic constriction injury-induced microRNA-146a-5p alleviates neuropathic pain through suppression of IRAK1/TRAF6 signaling pathway.

Similar Datasets

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