Stigmasterol regulates microglial M1/M2 polarization via the TLR4/NF-κB pathway to alleviate neuropathic pain.

(Switching from the microglial M1 phenotype to the M2 phenotype is a promising therapeutic strategy for neuropathic pain (NP). This study aimed to investigate the potential use of stigmasterol for treating NP. In animal experiments, 32 male Sprague-Dawley rats were randomly divided into the sham operation group, chronic constriction injury (CCI) group, CCI + ibuprofen group, and CCI + stigmasterol group. We performed behavioral tests, enzyme-linked immunosorbent assay, hematoxylin-esoin staining (H&E) staining and immunohistochemistry, immunofluorescence, and Western blotting. In cell experiments, we performed flow cytometry, immunofluorescence, Western blotting, and qRT-PCR. Stigmasterol reduced thermal and mechanical hyperalgesia and serum IL-1ß and IL-8 levels and increased serum IL-4 and TGF-ß levels in CCI rats. Stigmasterol reduced IL-1ß, COX-2, and TLR4 expression in the right sciatic nerve and IL-1ß expression in the spinal cord. Stigmasterol reduced the expression of Iba-1, TLR4, MyD88, pNF-κB, pP38 MAPK, pJNK, pERK, COX-2, IL-1ß, and CD32 in the spinal cord of CCI rats while increasing the expression of IL-10 and CD206. Stigmasterol decreased M1 polarization markers and increased M2 polarization markers in lipopolysaccharide (LPS)-induced microglia and decreased the expression of Iba-1, TLR4, MyD88, pNF-κB, pP38 MAPK, pJNK, pERK, iNOS, COX-2, and IL-1ß in LPS-treated microglia while increasing the expression of Arg-1 and IL-10. Stigmasterol regulates microglial M1/M2 polarization via the TLR4/NF-κB pathway to alleviate NP.

α-Asarone attenuates chronic sciatica by inhibiting peripheral sensitization and promoting neural repair.

This study explored the therapeutic effect of α-asarone on chronic sciatica. Thirty-two Sprague-Dawley (SD) rats were divided into four groups: the sham group, chronic constriction injury (CCI) group, pregabalin group, and α-asarone group. Hot hyperalgesia was induced after the CCI operation, and α-asarone was found to relieve chronic neuralgia. Furthermore, α-asarone reduced IL1ß, IL6, TNF-α, CRP, and LPS levels and increased IL10 levels in serum. α-Asarone decreased the protein levels of TRPA1, TRPM8, and TRPV1-4 and the mRNA levels of TRPA1, TRPM8, TRPV1-4, IL1ß, and TNF-α in dorsal root ganglion neurons. In the sciatic nerve, α-asarone treatment reduced the number of inflammatory cells and promoted the proliferation of Schwann cells, favouring recovery of the nerve structure. In cellular experiments, LPS induced Schwann cell apoptosis via TLR4/p38MAPK signalling; α-asarone attenuated LPS-induced Schwann cell apoptosis by decreasing TLR4, p-p38MAPK, cleaved-caspase3, and cleaved-caspase7 levels and increasing Bcl-2 and Bcl-xl expression. Overall, these findings suggest that α-asarone relieves chronic sciatica by decreasing the levels of inflammatory factors, inhibiting peripheral sensitization, and favouring the repair of damaged nerves.

Ferulic acid alleviates sciatica by inhibiting peripheral sensitization through the RhoA/p38MAPK signalling pathway.

BACKGROUND: Nonsteroidal anti-inflammatory drugs are used to relieve sciatica, but their effects are not satisfactory. PURPOSE: This study aimed to explore the therapeutic effects of ferulic acid on sciatica. METHODS: Thirty-two SD rats were randomly divided into 4 groups, i.e., sham operation group, chronic constriction injury (CCI) group, mecobalamin group, and ferulic acid group. We conducted behavioural tests, ELISA, PCR, Western blots, and immunofluorescence analysis. Specific inhibitors were used in cell experiments to explore the related mechanisms. RESULTS: Thermal hyperalgesia was induced after CCI operation, and ferulic acid relieved thermal hyperalgesia. In addition, ferulic acid decreased the IL1ß, IL6, TNF-α, and CRP mRNA levels; the IBA-1, iNOS, IL1ß, RhoA, RhoA-GTP, COX2, Rock1, TRPV1, TRPA1, and p-p38MAPK levels in dorsal root ganglion (DRG) neurons; and the LPS, CRP, substance P (SP), and prostaglandin E2 (PGE2) levels in serum, and these levels were higher in the CCI group. In the cell experiments, LPS induced M1 polarization of GMI-R1 cells via the RhoA/Rock pathway. Ferulic acid attenuated LPS-induced M1 polarization by decreasing the levels of M1 polarization markers, including IL1ß, IL6, TNF-α, iNOS, and CD32, and increased M2 polarization by increasing the levels of M2 polarization markers, including CD206 and Arg-1. LPS treatment clearly increased the iNOS, IL1ß, RhoA, Rock1, Rock2 and p-p38 MAPK levels and reduced Arg-1 expression, and ferulic acid reversed these changes. CONCLUSION: Ferulic acid can inhibit peripheral sensitization by reducing the levels of inflammatory factors, TRPA1 and TRPV1 through the RhoA/p38 MAPK pathway to alleviate sciatica.

The combination of Lonicerae Japonicae Flos and Forsythiae Fructus herb-pair alleviated inflammation in liver fibrosis.

Objective: To explore the active components and epigenetic regulation mechanism underlying the anti-inflammatory effects of Lonicerae Japonicae Flos and Forsythiae Fructus herb-pair (LFP) in carbon tetrachloride (CCl4)-induced rat liver fibrosis. Methods: The main active ingredients and disease-related gene targets of LFP were determined using TCMSP and UniProt, and liver fibrosis disease targets were screened in the GeneCards database. A network was constructed with Cytoscape 3.8.0 and the STRING database, and potential protein functions were analyzed using bioinformatics analysis. Based on these analyses, we determined the main active ingredients of LFP and evaluated their effects in a CCl4-induced rat liver fibrosis model. Serum biochemical indices were measured using commercial kits, hepatocyte tissue damage and collagen deposition were evaluated by histopathological studies, and myofibroblast activation and inflammation were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting. High-performance liquid chromatography-mass spectrometry was performed to determine the levels of homocysteine, reduced glutathione, and oxidized glutathione, which are involved in inflammation and oxidative stress. Results: The main active components of LFP were quercetin, kaempferol, and luteolin, and its main targets were α-smooth muscle actin, cyclooxygenase-2, formyl-peptide receptor-2, prostaglandin-endoperoxide synthase 1, nuclear receptor coactivator-2, interleukinß, tumor necrosis factor α, CXC motif chemokine ligand 14, and transforming growth factor ß1. A combination of quercetin, kaempferol, and luteolin alleviated the symptoms of liver fibrosis. Conclusion: The results of this study support the role of LFP in the treatment of liver fibrosis, and reveal that LFP reduces collagen formation, inflammation, and oxidative stress. This study suggests a potential mechanism of action of LFP in the treatment of liver fibrosis.

Therapeutic effect of paeoniflorin on chronic constriction injury of the sciatic nerve via the inhibition of Schwann cell apoptosis.

Therapeutic drugs of chronic neuralgia have a high risk of addiction, making it crucial to identify novel drugs for chronic neuralgia. This study aimed to explore the therapeutic effect of paeoniflorin on chronic sciatica via inhibiting Schwann cell apoptosis. 28 SD rats were randomly divided into four groups, including the sham operation group, chronic constriction injury (CCI) group, mecobalamin group, and paeoniflorin group. The therapeutic effect and mechanism of paeoniflorin were evaluated via rat and cell experiments. Mechanical, hot, or cold hyperalgesia was induced in the rats after CCI operation, while paeoniflorin relieved chronic neuralgia. Besides, paeoniflorin decreased the levels of IL1, IL6, TNF-α, CRP, and LPS and increased the level of IL10 in serum. As for the sciatic nerve, the number of inflammatory cells was decreased, and Schwann cells were present after paeoniflorin treatment, and paeoniflorin promoted the recovery of nerve structure. In cell experiments, LPS induced Schwann cell apoptosis via the TLR4/NF-kB pathway. And paeoniflorin attenuated LPS-induced Schwann cell apoptosis by decreasing the levels of TLR4, p-NF-kB, caspase3, cleaved-caspase3, and cleaved-caspase7. Overall, these results suggest that paeoniflorin alleviates chronic sciatica by decreasing inflammatory factor levels and promotes the repair of damaged nerves by reducing Schwann cell apoptosis.

Kaempferol exerts a neuroprotective effect to reduce neuropathic pain through TLR4/NF-ĸB signaling pathway.

Switching microglial polarization from the M1 to M2 phenotype is a promising therapeutic strategy for neuropathic pain (NP). Toll-like receptor 4 (TLR4) is activated by lipopolysaccharide (LPS). Uncontrolled activation of TLR4 has been proven to trigger chronic inflammation. Kaempferol, a dietary flavonoid, is known to have anti-inflammatory properties. This study is aimed to investigate the analgesic and anti-inflammatory effects and the underlying mechanisms of kaempferol, which were explored with an NP model in vivo and LPS-induced injury in microglial BV2 cells in vitro. The levels of proinflammatory cytokines were evaluated. H&E staining and immunohistochemistry were used to assess the sciatic nerve condition after chronic constriction injury surgery. Western blotting and immunofluorescence were used to determine whether TLR4/NF-ĸB signaling pathway plays a major role in kaempferol-mediated alleviation of neuroinflammation. Quantitative real-time polymerase chain reaction and flow cytometry were used to examine the modulator effect of kaempferol on microglial M1/M2 polarization. We found that kaempferol treatment can significantly reduce NP and proinflammatory cytokine production. Kaempferol attenuated the activation of TLR4/NF-κB pathways in LPS-activated BV2 cells. The analgesic effects of kaempferol on NP may be due to inhibition of microglia activation and switching the M1 to M2 phenotype.

Protective effect of paeoniflorin on H2O2 induced Schwann cells injury based on network pharmacology and experimental validation.

This study was to investigate the protective effect of paeoniflorin (PF) on hydrogen peroxide-induced injury. Firstly, "SMILES" of PF was searched in Pubchem and further was used for reverse molecular docking in Swiss Target Prediction database to obtain potential targets. Injury-related molecules were obtained from GeenCards database, and the predicted targets of PF for injury treatment were selected by Wayne diagram. For mechanism analysis, the protein-protein interactions were constructed by String, and the KEGG analysis was conducted in Webgestalt. Then, cell viability and cytotoxicity assay were established by CCK8 assay. Also, the experimental cells were allocated to control, model (200 µmol·L-1 H2O2), SB203580 10 µmol·L-1 (200 µmol·L-1 H2O2+ SB203580 10 µmol·L-1), PF 50 µmol·L-1 (200 µmol·L-1 H2O2+ PF 50 µmol·L-1), and PF 100 µmol·L-1 (200 µmol·L-1 H2O2+ PF 100 µmol·L-1) groups. We measured the intracellular ROS, Hoechst 33258 staining, cell apoptosis, the levels of Bcl-xl, Bcl-2, Caspase-3, Cleaved-caspase3, Cleaved-caspase7, TRPA1, TRPV1, and the phosphorylation expression of p38MAPK. There are 96 potential targets that may be associated with PF for injury treatment. Then, we chose the "Inflammatory mediator regulation of TRP channels" pathway for the experimental verification from the first 10 KEGG pathway. In experimental verification, H2O2 decreased the cell viability moderately (P < 0.05), and 100 µmol·L -1 PF increased the cell viability significantly (P < 0.05). Depending on the difference of intracellular ROS fluorescence intensity, PF inhibited H 2O2-induced reactive oxygen species production in Schwann cells. In Hoechst 33258 staining, PF reversed the condensed chromatin and apoptotic nuclei following H2O2 treatment. Moreover, Flow cytometry results showed that PF could substantially inhibit H2O2 induced apoptosis (P < 0.05). Pretreatment with PF obviously reduced the levels of Caspase3, Cleaved-caspase3, Cleaved-caspase7, TRPA1, TRPV1, and the phosphorylation expression of p38MAPK after H 2O2 treatment (P < 0.05), increased the levels of Bcl-2, and Bcl-xl ( P < 0.05). PF inhibited Schwann cell injury and apoptosis induced by hydrogen peroxide, which mechanism was linked to the inhibition of phosphorylation of p38MAPK.