Daphnetin Ameliorates Neuropathic Pain via Regulation of Microglial Responses and Glycerophospholipid Metabolism in the Spinal Cord.

Neuropathic pain (NP) is a common type of chronic pain caused by a lesion or disease of the somatosensory nervous system. This condition imposes a considerable economic burden on society and patients. Daphnetin (DAP) is a natural product isolated from a Chinese medicinal herb with various pharmacological activities, such as anti-inflammatory and analgesic properties. However, the underlying mechanisms of these effects are not fully understood. In the present study, we aimed to investigate DAP's anti-inflammatory and analgesic effects and explore the underlying mechanisms of action. The NP model was established as chronic constrictive injury (CCI) of the sciatic nerve, and pain sensitivity was evaluated by measuring the mechanical withdrawal threshold (MWT) and thermal withdrawal threshold (TWT). The activation of microglia in the spinal dorsal horn was measured via immunofluorescence staining. Protein levels were measured using a western blot assay. Using a mass-spectrometry proteomics platform and an LC-MS/MS-based metabolomics platform, proteins and metabolites in spinal cord tissues were extracted and analyzed. DAP treatment ameliorated the MWT and TWT in CCI rats. The expression of IL-1ß, IL-6, and TNF-α was inhibited by DAP treatment in the spinal cords of CCI rats. Moreover, the activation of microglia was suppressed after DAP treatment. The elevation in the levels of P2X4, IRF8, IRF5, BDNF, and p-P38/P38 in the spinal cord caused by CCI was inhibited by DAP. Proteomics and metabolomics results indicated that DAP ameliorated the imbalance of glycerophospholipid metabolism in the spinal cords of CCI rats. DAP can potentially ameliorate NP by regulating microglial responses and glycerophospholipid metabolism in the CCI model. This study provides a pharmacological justification for using DAP in the management of NP.

Daphnetin Improves Neuropathic Pain by Inhibiting the Expression of Chemokines and Inflammatory Factors in the Spinal Cord and Interfering with Glial Cell Polarization.

Neuropathic pain (NP) is a common pain disease that seriously affects the quality of life and physical and mental health of patients. Daphnetin is extracted from the Daphne giraldii Nitsche and has the structure of 7,8-dihydroxy coumarin. As a natural product, daphnetin displays a wide range of pharmacological activities, such as analgesia and anti-inflammatory activities, but whether it is able to improve NP through anti-inflammatory effects is unknown. Therefore, this paper intends to investigate the mechanism of daphnetin in improving NP rats affected by the intrathecal injection of tumor necrosis factor-α (TNF-α) from the perspective of anti-inflammation. Our results showed that daphnetin significantly improved hyperalgesia in NP rats. Daphnetin inhibited the activation and polarization of glial cells and neurons in the spinal cord of NP rats and reduced the expression of mRNA and protein of inflammatory factors and chemokine pairs in the spinal cord. Daphnetin inhibited the polarization of human microglia cell 3 (HMC3) cells and human glioma cells (U251) cells toward M1 microglia and A1 astrocytes, respectively, and induced the conversion of M1 microglia and A1 astrocytes to M2 microglia and A2 astrocytes, respectively. In conclusion, daphnetin ameliorates NP by inhibiting the expression of inflammatory factors and chemokines and the polarization of glial cells in the spinal cord of NP rats. This study provides a theoretical basis for the treatment of NP with daphnetin to expand the clinical application of daphnetin.

Daphnetin alleviates neuropathic pain in chronic constrictive injury rats via regulating the NF-κB dependent CXCL1/CXCR2 signaling pathway.

CONTEXT: Daphnetin is a natural product with anti-inflammatory, antioxidant, and neuroprotective properties. Reports have found that it has a strong analgesic effect; however, its analgesic mechanism is unknown. OBJECTIVE: We explored the effect and mechanism of daphnetin on neuropathic pain (NP). MATERIALS AND METHODS: The rat model of NP was established by ligation of the sciatic nerve. Male Sprague-Dawley rats were divided into six groups: Control, Model, Sham, morphine (0.375 mg/kg), and daphnetin (0.0625 and 0.025 mg/kg). Rats were intrathecally injected with drugs or normal saline once daily for three days. Hyperalgesia was evaluated by mechanical withdrawal threshold (MWT) and thermal withdrawal threshold (TWT). Protein levels were detected using ELISA, immunofluorescence, and western blotting. RESULTS: Compared to the Model group, daphnetin improved TWT (46.70 °C vs. 42.20 °C) and MWT (45.60 g vs. 23.60 g), reduced the expression of interleukin-1ß (0.99 ng/g vs. 1.42 ng/g), interleukin-6 (0.90 ng/g vs. 1.52 ng/g), and tumor necrosis factor-α (0.93 ng/g vs. 1.52 ng/g) in the sciatic nerve. Daphnetin decreased the expression of toll-like receptor 4 (TLR4) (0.47-fold), phosphorylated inhibitor of NF-κB (p-IKBα) (0.29-fold), nuclear factor kappaB (NF-κB) (0.48-fold), glial fibrillary acidic protein (GFAP) (0.42-fold), CXC chemokine ligand type 1 (CXCL1) (0.84-fold), CXC chemokine receptor type 2 (CXCR2) (0.78-fold) in the spinal cord. DISCUSSION AND CONCLUSIONS: Daphnetin alleviates NP by inhibiting inflammation and astrocyte activation in the spinal cord, providing theoretical support for the extensive clinical treatment of NP.

The core of maintaining neuropathic pain: Crosstalk between glial cells and neurons (neural cell crosstalk at spinal cord).

BACKGROUND: Neuropathic pain (NP) caused by the injury or dysfunction of the nervous system is a chronic pain state accompanied by hyperalgesia, and the available clinical treatment is relatively scarce. Hyperalgesia mediated by pro-inflammatory factors and chemokines plays an important role in the occurrence and maintenance of NP. DATA TREATMENT: Therefore, we conducted a systematic literature review of experimental NP (PubMed Medline), in order to find the mechanism of inducing central sensitization and explore the intervention methods of hyperalgesia caused by real or simulated injury. RESULT: In this review, we sorted out the activation pathways of microglia, astrocytes and neurons, and the process of crosstalk among them. It was found that in NP, the microglia P2X4 receptor is the key target, which can activate the mitogen-activated protein kinase pathway inward and then activate astrocytes and outwardly activate neuronal tropomyosin receptor kinase B receptor to activate neurons. At the same time, activated neurons continue to maintain the activation of astrocytes and microglia through chemokines on CXCL13/CXCR5 and CX3CL1/CX3CR1. This crosstalk process is the key to maintaining NP. CONCLUSION: We summarize the further research on crosstalk among neurons, microglia, and astrocytes in the central nervous system, elaborate the ways and connections of relevant crosstalk, and find potential crosstalk targets, which provides a reference for drug development and preclinical research.

Aperture Modulation of Isoreticular Metal Organic Frameworks for Targeted Antitumor Drug Delivery.

The introduction of different pore diameters in metal organic frameworks (MOFs) could adjust their drug delivery performance. MOFs with customized structures have potential application value in targeted drug delivery. However, no research on this topic has been found so far. In this report, isoreticular metal organic frameworks (IRMOFs) have been taken as a typical case of tailor-made MOFs, the pore size of which is enlarged (average BJH pore sizes of about 2.43, 3.06, 5.47, and 6.50 nm were determined for IRMOF-1, IRMOF-8, IRMOF-10, and IRMOF-16, respectively), emphasizing the relationship between pore size and model drugs (Oridonin, ORI) and clarifying its potential working mechanism. IRMOF-1, whose pore size matches the size of ORI, has an outstanding drug loading capacity (57.93% by wt) and release profile (about 90% in 24 h at pH 7.4). IRMOF-1 was further coated with polyethylene glycol (PEG) modified with a cell penetrating peptide (CPP44) bound to M160 (CD163L1) protein for targeting of hepatic tumor lines. This nanoplatform (CPP44-PEG@ORI@IRMOF-1) exhibited acid-responsive drug release behavior (37.86% in 10 h at pH 7.4 and 66.66% in 10 h at pH 5.5) and significantly enhanced antitumor effects. The results of cell targeting and in vivo animal imaging indicated that CPP44-PEG@ORI@IRMOF-1 may serve as a tumor-selective drug delivery nanoplatform. Toxicity assessment confirmed that PEGylated IRMOF-1 did not cause organ or systemic toxicity. Furthermore, it is encouraging that the IRMOF-based targeted drug delivery system with pore size modulation showed rapid clearance (most administered NPs are metabolized from urine and feces within 1 week) and avoided accumulation in the body, indicating their promise for biomedical applications. This MOF-based aperture modulation combined with a targeted modification strategy might find broad applications in cancer theranostics. Thus, it is convenient to customize personalized MOFs according to the size of drug molecules in future research.

Chinese Herbal Medicine Alleviates Myocardial Ischemia/Reperfusion Injury by Regulating Endoplasmic Reticulum Stress.

Myocardial ischemia/reperfusion injury is the main cause of increased mortality and disability in cardiovascular diseases. The injury involves many pathological processes, such as oxidative stress, calcium homeostasis imbalance, inflammation, and energy metabolism disorders, and these pathological stimuli can activate endoplasmic reticulum stress. In the early stage of ischemia, endoplasmic reticulum stress alleviates the injury as an adaptive survival response, but the long-term stress on endoplasmic reticulum amplifies oxidative stress, inflammation, and calcium overload to accelerate cell damage and apoptosis. Therefore, regulation of endoplasmic reticulum stress may be a mechanism to improve ischemia/reperfusion injury. Chinese herbal medicine has a long history of clinical application and unique advantages in the treatment of ischemic heart diseases. This review focuses on the effect of Chinese herbal medicine on myocardial ischemia/reperfusion injury from the perspective of regulation of endoplasmic reticulum stress.

Focally amplified lncRNA on chromosome 1 regulates apoptosis of esophageal cancer cells via DRP1 and mitochondrial dynamics.

Long noncoding RNAs (lncRNAs), a family of noncoding RNA transcripts with a length of <200 nucleotides (nts), have been associated with the pathological development of various types of carcinogenesis. Focally amplified lncRNA on chromosome 1 (FAL1) is a recently identified lncRNA. In the current study, we aimed to investigate the physiological function of FAL1 in esophageal squamous cell carcinoma (ESCC). Our findings demonstrate that FAL1 was associated with esophageal cancer cell survival by regulating mitochondrial fission. First, we found that the expression of the mitochondrial fission protein dynamin-related protein 1 (DRP1) was significantly reduced, but the expression of the mitochondrial fusion protein mitofusin 1 (Mfn1) was increased in ESCC tissues and esophageal cancer cell lines as compared with adjacent normal tissues and a normal esophagus epithelial cell line. In addition, we found that reduced expression of DRP1 in the esophageal cancer cell lines KYSE450 and EC9706 cells was associated with increased expression of FAL1. Inhibition of FAL1 promoted mitochondrial fission and mitochondrial dysfunction in KYSE450 and EC9706 cells mediated by DRP1. Silencing of DRP1 abolished FAL1-induced apoptosis through a mitochondrial-dependent pathway. Our findings suggest that FAL1/DRP1 could be a therapeutic target for the treatment of ESCC. © 2018 IUBMB Life, 71(1):254-260, 2019.