Project description:We aimed to identify neuropathic pain (NP)-related immune semaphorins (SEMAs) and assess the efficacy of SEMA targeted therapy for NP. We quantified serum SEMA3A, 3E, 4A, 4D, and 7A in 45 patients with NP and 17 age- and sex-matched healthy controls (HCs) by enzyme-linked immunosorbent assay (ELISA). SEMA expression in DRG and peripheral nerve (PN) tissues of autopsied/biopsied patients with NP and controls as well as NP mouse model with partial sciatic nerve ligation (PSNL) was assessed by immunohistochemistry. Moreover, we intraperitoneally injected SEMA-blocking IgG or control IgG into PSNL-operated mice for 5 consecutive days immediately and 14 days after PSNL, and assessed mechanical hypersensitivity using von Frey filament on day 4 and 18 after PSNL. In vitro, we evaluated neurite outgrowth and the gene expression by RNA microarray analysis of mouse DRG neurons treated with or without SEMA3E. ELISA showed a significant increase of the SEMA3E in NP patients compared to HCs. Immunohistochemistry revealed enhanced SEMA3E expression in DRG and PN tissues of both NP patients and mouse model, especially in pro-inflammatory macrophages. SEMA3E-blocking IgG injection not only abolished the pro-inflammatory macrophage accumulation in PNs but also resolved hypersensitivity in PSNL-operated mice on both days 4 and 18. In vitro, SEMA3E treatment inhibited neurite outgrowth of DRG neurons accompanied with the upregulation of S100A9 which promotes neuroinflammation and downregulation of Dync1h1 that promote neurite outgrowth compared to non-treated DRG neurons. SEMA3E inhibition is a potential therapeutic strategy for NP via regulating neuroinflammation.
Project description:This program addresses the gene signature associated with DRG in the Chung rat model for neuropathic pain. The Chung neuropathic pain profiling data was analyzed by identifying genes that were up- and down-regulated at selected p value and fold change in DRG of the Sprague Dawley rats following spinal nerve ligation compared to the sham-operated controls.
Project description:• Project description: Why only half of the idiopathic peripheral polyneuropathy (IPN) patients develop neuropathic pain is unknown. By conducting a proteomics analysis on IPN patients, we aimed to discover proteins and new pathways that are associated with neuropathic pain. We conducted unbiased mass-spectrometry proteomics analysis on blood plasma from 31 IPN patients with severe neuropathic pain and 29 IPN patients with no pain, to investigate protein biomarkers and protein-protein interactions associated with neuropathic pain. Univariate modeling was done with Linear mixed modeling (LMM) and corrected for multiple testing. Multivariate modelling was performed using elastic net analysis and validated with internal cross validation and bootstrapping.
Project description:Neuropathic pain causes severe suffering and most patients are resilient to current therapies. A core element of neuropathic pain is the loss of inhibitory tone in the spinal cord. Previous studies have shown that foetal GABAergic neuron precursors can provide relief from pain. However, the source of these precursor cells and their multipotent status make them unsuitable for therapeutic use. Here we extend these findings by showing, for the first time, that spinally transplanted, terminally differentiated hiPSC-derived GABAergic (iGABAergic) neurons provide significant, long-term and safe relief from neuropathic pain induced by peripheral nerve injury in mice. Furthermore, iGABAergic Neuron transplants survive long term in the injured spinal cord and show evidence of synaptic integration. Together, this provides the proof in principle for the first viable GABAergic transplants to treat human neuropathic pain patients.
Project description:Peripheral nerve injury alters the expression of hundreds of proteins in dorsal root ganglia (DRG). Targeting some of these proteins has led to successful treatments for acute pain, but not for sustained postoperative neuropathic pain. The latter may require targeting multiple proteins. Since a single microRNA (miR) can affect the expression of multiple proteins, here, we describe an approach to identify chronic neuropathic pain-relevant miRs. We used two variants of the spared nerve injury (SNI): Sural-SNI and Tibial-SNI and found distinct pain phenotypes between the two. Both models induced strong mechanical allodynia, but only Sural-SNI rats maintained strong mechanical and cold allodynia, as previously reported. In contrast, we found that Tibial-SNI rats recovered from mechanical allodynia and never developed cold allodynia. Since both models involve nerve injury, we increased the probability of identifying differentially regulated miRs that correlated with the quality and magnitude of neuropathic pain and decreased the probability of detecting miRs that are solely involved in neuronal regeneration. We found seven such miRs in L3-L5 DRG. The expression of these miRs increased in Tibial-SNI. These miRs displayed a lower level of expression in Sural-SNI, with four having levels lower than those in sham animals. Bioinformatics analysis of how these miRs could affect the expression of some ion channels supports the view that, following a peripheral nerve injury, the increase of the 7 miRs may contribute to the recovery from neuropathic pain while the decrease of four of them may contribute to the development of chronic neuropathic pain. The approach used resulted in the identification of a small number of potentially neuropathic pain relevant miRs. Additional studies are required to investigate whether manipulating the expression of the identified miRs in primary sensory neurons can prevent or ameliorate chronic neuropathic pain following peripheral nerve injuries. To identify the miRs that were differentially dysregulated between Tibial-SNI and Sural-SNI, we first performed 12 microarrays in a limited number of samples (in four individual DRGs per group: Sham, Tibial-SNI and Sural-SNI; two L3-DRG and two L4-DRG). Then, miRs identified as having differential expression were corroborated with real time qRT-PCR in RNA isolated from individual DRGs (L3, L4 and L5) derived from 4 rats per group (not presented here, but in the manuscript).
Project description:Treating neuropathic pain is challenging and novel non-opioid based medicines are needed. Using unbiased receptomics, transcriptomic analyses, immunofluorescence and in situ hybridization, expression of the orphan GPCR (oGPCR) GPR160 increased in the rodent dorsal horn of the spinal cord (DH-SC) following traumatic nerve injury. Genetic and immunopharmacological approaches demonstrated that GPR160 inhibition in the spinal cord prevented and reversed neuropathic pain in male and female rodents without altering normal pain response. GPR160 inhibition in the spinal cord attenuated sensory processing in the thalamus, a key relay in the sensory discriminative pathways of pain. We also identified cocaine- and amphetamine-regulated transcript peptide (CARTp) as a GPR160 ligand. Inhibiting endogenous CARTp signaling in spinal cord attenuated neuropathic pain, whereas exogenous intrathecal (i.th.) CARTp evoked painful hypersensitivity through GPR160-dependent ERK and cAMP response element-binding protein (CREB). Our findings de-orphanize GPR160, identify it as a determinant of neuropathic pain and potential therapeutic target, and provide insights to its signaling pathways. CARTp is involved in many diseases including depression, reward and addiction, de-orphanization of GPR160 is a major step forward understanding the role of CARTp signaling in health and disease.
Project description:Astrocytes in the spinal cord dorsal horn (SDH) play a pivotal role in synaptic transmission and neuropathic pain. However, the precise classification of SDH astrocytes in health and disease remains elusive. Here we reveal Gpr37l1 as a marker and functional regulator of spinal astrocytes. Through single-nucleus RNA sequencing, we identified Gpr37l1 as a selective GPCR marker for spinal cord astrocytes. Notably, SDH displayed reactive astrocyte phenotypes and exacerbated neuropathic pain following nerve injury combined with Gpr37l1 deficiency. In naïve animals, GPR37L1 knockdown in SDH astrocytes induces astrogliosis and pain hypersensitivity, while Gpr37l1-/- mice fail to recover from neuropathic pain. GPR37L1 activation by maresin-1 increased astrocyte GLT-1 activity and reduced spinal EPSCs and neuropathic pain. Selective overexpression of Gpr37l1 in SDH astrocytes reversed neuropathic pain and astrogliosis after nerve injury. Our findings illuminate astrocyte GPR37l1 as an essential negative regulator of pain, which protects neuropathic pain through astrocyte signaling in SDH.
Project description:Neuropathic pain is an apparently spontaneous experience triggered by abnormal physiology of the peripheral or central nervous system, which evolves with time. Neuropathic pain arising from peripheral nerve injury is characterized by a combination of spontaneous pain, hyperalgesia and allodynia. There is no evidence of this type of pain in human infants or rat pups; brachial plexus avulsion, which causes intense neuropathic pain in adults, is not painful when the injury is sustained at birth. Since infants are capable of nociception from before birth and display both acute and chronic inflammatory pain behaviour from an early neonatal age, it appears that the mechanisms underlying neuropathic pain are differentially regulated over a prolonged postnatal period. We used microarrays to detail the global programme of gene expression underlying the differences in nerve injury between along the postnatal development and identified distinct classes of regulated genes during the injury Experiment Overall Design: We have performed a microarray analysis of the rat L4/L5 dorsal root ganglia, 7 days post spared nerve injury, a model of neuropathic pain. Genes that are regulated in adult rats displaying neuropathic behaviour were compared to those regulated in young rats (10 days old) that did not show the same neuropathic behaviour.
Project description:Neuropathic pain (NP) is a complex chronic pain due to the nervous system damage or diseases.During NP development and progression, the neuroinflammation has been observed along the pain pathways from the spinal cord to the thalamus and the parietal cortex. It may be caused by the activation of glial cells, especially microglia, with production of cytokines and other inflammatory mediators within the central nervous system (CNS), especially in spinal cord. In this study, we used high-throughput RNA-seq technology to detect the global gene expression in spinal cord of rats in sham group and CCI model group(an animal model of neuropathic pain), and the differentially expressed genes between diseases and control group were obtained.Significant differentially expressed genes (DEGs) of the Sham vs. CCI groups were identified using the criteria of a fold change>1.5 and P value <0.05. Finally, we focused on C/EBPβ-Clec7a Cross-talk-mediated NLRP3 Inflammasome-dependent Pyroptosis pathway and further studied its role in neuropathic pain.
Project description:Maladaptive changes of nerve injury–associated genes in dorsal root ganglia (DRGs) are critical for neuropathic pain genesis. Emerging evidence supports the role of long noncoding RNAs (lncRNAs) in regulating gene transcription. Here we identified a conserved lncRNA, named nerve injury–specific lncRNA (NIS-lncRNA) for its upregulation in injured DRGs exclusively in response to nerve injury. This upregulation was triggered by nerve injury–induced increase in DRG ELF1, a transcription factor that bound to the NIS-lncRNA promoter. Blocking this upregulation attenuated nerve injury–induced CCL2 increase in injured DRGs and nociceptive hypersensitivity during the development and maintenance periods of neuropathic pain. Mimicking NIS-lncRNA upregulation elevated CCL2 expression, increased CCL2-mediated excitability in DRG neurons, and produced neuropathic pain symptoms. Mechanistically, NIS-lncRNA recruited more binding of the RNA-interacting protein FUS to the Ccl2 promoter and augmented Ccl2 transcription in injured DRGs. Thus, NIS-lncRNA participates in neuropathic pain likely by promoting FUS-triggered DRG Ccl2 expression and may be a potential target in neuropathic pain management.