RESUMEN

The factors that contribute to pain after nerve injury remain incompletely understood. Laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) are common surgical techniques to correct refractive errors. After LASIK or PRK, a subset of patients suffers intense and persistent pain, of unknown origin, described by patients as feeling like shards of glass in their eye. Here, we evaluated a TRPV1 variant, p.V527M, found in a 49-y-old woman who developed corneal pain after LASIK and subsequent PRK enhancement, reporting an Ocular Surface Disease Index score of 100. Using patch-clamp and Ca2+ imaging, we found that the V527M mutation enhances the response to acidic pH. Increasing proton concentration induced a stronger leftward shift in the activation curve of V527M compared to WT, resulting in channel activity of the mutant in acidic pH at more physiological membrane potentials. Finally, comparing the responses to consecutive applications of different agonists, we found in V527M channels a reduced capsaicin-induced desensitization and increased sensitization by the arachidonic acid metabolite 12-hydroxyeicosatetraenoic acid (12-HETE). We hypothesize that the increased response in V527M channels to protons and enhanced sensitization by 12-HETE, two inflammatory mediators released in the cornea after tissue damage, may contribute to the pathogenesis of corneal neuralgia after refractive surgery.

Asunto(s)

Bradiquinina , Capsaicina , Mutación , Neuralgia , Canales Catiónicos TRPV , Animales , Humanos , Ratas , Bradiquinina/metabolismo , Bradiquinina/farmacología , Capsaicina/farmacología , Córnea/metabolismo , Córnea/patología , Células HEK293 , Concentración de Iones de Hidrógeno , Neuralgia/genética , Neuralgia/metabolismo , Neuralgia/etiología , Queratectomía Fotorrefractiva/efectos adversos , Canales Catiónicos TRPV/genética , Canales Catiónicos TRPV/metabolismo

RESUMEN

Neuropathic pain is characterised by periodic or continuous hyperalgesia, numbness, or allodynia, and results from insults to the somatosensory nervous system. Peripheral nerve injury induces transcriptional reprogramming in peripheral sensory neurons, contributing to increased spinal nociceptive input and the development of neuropathic pain. Effective treatment for neuropathic pain remains an unmet medical need as current therapeutics offer limited effectiveness and have undesirable effects. Understanding transcriptional changes in peripheral nerve injury-induced neuropathy might offer a path for novel analgesics. Our literature search identified 65 papers exploring transcriptomic changes post-peripheral nerve injury, many of which were conducted in animal models. We scrutinize their transcriptional changes data and conduct gene ontology enrichment analysis to reveal their common functional profile. Focusing on genes involved in 'sensory perception of pain' (GO:0019233), we identified transcriptional changes for different ion channels, receptors, and neurotransmitters, shedding light on its role in nociception. Examining peripheral sensory neurons subtype-specific transcriptional reprograming and regeneration-associated genes, we delved into downstream regulation of hypersensitivity. Identifying the temporal program of transcription regulatory mechanisms might help develop better therapeutics to target them effectively and selectively, thus preventing the development of neuropathic pain without affecting other physiological functions.

Asunto(s)

Neuralgia , Traumatismos de los Nervios Periféricos , Animales , Traumatismos de los Nervios Periféricos/genética , Traumatismos de los Nervios Periféricos/metabolismo , Neuralgia/genética , Neuralgia/metabolismo , Humanos , Transcriptoma , Células Receptoras Sensoriales/metabolismo

RESUMEN

There has been significant progress in our understanding of the molecular basis by which nociceptors transduce and transmit noxious (tissue damaging) stimuli. This is dependent on ion channels, many of which are selectively expressed in nociceptors. Mutations in such proteins have recently been linked to inherited pain disorders in humans. An exemplar is the voltage-gated sodium channel (VGSC) NaV1.7. Loss of function mutations in NaV1.7 result in congenital inability to experience pain while gain-of-function mutations can cause a number of distinct neuropathic pain disorders, including erythromelalgia, paroxysmal extreme pain disorder, and small-fiber neuropathy. Furthermore, variants in the VGSCs 1.8 and 1.9 have also been linked to human pain disorders. There is a correlation between the impact of mutations on the biophysical properties of the ion channel and the severity of the clinical phenotype. Pain channelopathies are not restricted to VGSCs: a mutation in the ligand-gated ion channel TRPA1, (which responds to environmental irritants) causes a familial episodic pain disorder. Ion channel variants have also been linked to more common neuropathic pain disorders such as painful diabetic neuropathy. Not only do these ion channels present targets for novel analgesics, but stratification based on genotype may improve treatment selection of existing analgesics.

Asunto(s)

Canalopatías , Humanos , Canalopatías/genética , Mutación/genética , Canal de Sodio Activado por Voltaje NAV1.7/genética , Dolor/genética , Neuralgia/genética

RESUMEN

Neuropathic pain is a highly prevalent and refractory condition, yet its mechanism remains poorly understood. While NR1, the essential subunit of NMDA receptors, has long been recognized for its pivotal role in nociceptive transmission, its involvement in presynaptic stimulation is incompletely elucidated. Transcription factors can regulate the expression of both pro-nociceptive and analgesic factors. Our study shows that transcription factor TFAP2A was up-regulated in the dorsal root ganglion (DRG) neurons, satellite glial cells (SGCs), and Schwann cells following spinal nerve ligation (SNL). Intrathecal injection of siRNA targeting Tfap2a immediately or 7 days after SNL effectively alleviated SNL-induced pain hypersensitivity and reduced Tfap2a expression levels. Bioinformatics analysis revealed that TFAP2A may regulate the expression of the Grin1 gene, which encodes NR1. Dual-luciferase reporter assays confirmed TFAP2A's positive regulation of Grin1 expression. Notably, both Tfap2a and Grin1 were expressed in the primary SGCs and upregulated by lipopolysaccharides. The expression of Grin1 was also down-regulated in the DRG following Tfap2a knockdown. Furthermore, intrathecal injection of siRNA targeting Grin1 immediately or 7 days post-SNL effectively alleviated SNL-induced mechanical allodynia and thermal hyperalgesia. Finally, intrathecal Tfap2a siRNA alleviated SNL-induced neuronal hypersensitivity, and incubation of primary SGCs with Tfap2a siRNA decreased NMDA-induced upregulation of proinflammatory cytokines. Collectively, our study reveals the role of TFAP2A-Grin1 in regulating neuropathic pain in peripheral glia, offering a new strategy for the development of novel analgesics.

Asunto(s)

Ganglios Espinales , Neuralgia , Neuroglía , Receptores de N-Metil-D-Aspartato , Factor de Transcripción AP-2 , Animales , Neuralgia/metabolismo , Neuralgia/genética , Ganglios Espinales/metabolismo , Factor de Transcripción AP-2/genética , Factor de Transcripción AP-2/metabolismo , Masculino , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo , Neuroglía/metabolismo , Ratones , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Regulación de la Expresión Génica , Ratones Endogámicos C57BL , Ratas Sprague-Dawley , Hiperalgesia/metabolismo , Hiperalgesia/genética

RESUMEN

OBJECTIVE: To observe the analgesic effects of Tuina on neuropathic pain (NPP) and the underlying mechanisms. METHODS: Forty-eight Sprague-Dawley (SD) rats were assigned by random into three treatment groups: sham, chronic constriction injury (CCI), and Tuina. Each group contained sixteen rats. CCI model was generated by ligating the right sciatic nerve. Behavioral changes of CCI were assessed by the paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). In addition, biochemical techniques such as immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA) and Western blotting were used to profile levels of microglia activation and inflammatory factors in the spinal dorsal horn (SDH) of rats. Tuina (clockwise pressing and rubbing) was performed at Chengshan (BL57) to observe the analgesic effects on CCI rats and the underlying mechanisms. RESULTS: Rats with CCI experienced significant reduction in the PWT and PWL of the right hind paw relative to CCI group at day 3. Tuina treatment rescued this situation significantly on days 10 and 14. Besides, Iba-1, microglia M1 receptor CD68, tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) were higher in the right SDH for CCI group compared to the sham group on day 14. As expected, Tuina partially downregulated the CCI-induced overexpressed Iba-1, CD68, TNF-α, and IL-1ß in the SDH of CCI model. CONCLUSION: Tuina induces a time-dependent cumulative analgesic effect in CCI rats by inhibiting the activation of microglia and the secretion of IL-1ß and TNF-α in SDH.

Asunto(s)

Microglía , Neuralgia , Ratas Sprague-Dawley , Médula Espinal , Animales , Neuralgia/metabolismo , Neuralgia/genética , Microglía/metabolismo , Ratas , Masculino , Médula Espinal/metabolismo , Medicamentos Herbarios Chinos/administración & dosificación , Citocinas/metabolismo , Citocinas/genética , Humanos , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismo , Factor de Necrosis Tumoral alfa/inmunología , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Analgésicos

RESUMEN

Aim: Diabetic peripheral neuropathy (DPN) induces chronic neuropathic pain in diabetic patients. Current treatments like pregabalin and duloxetine offer limited efficacy. This study evaluates combining pregabalin and duloxetine versus pregabalin alone for DPN pain relief, and explores gene modulation (PPARγ and Akt) to understand neuropathic pain's molecular basis.Materials & methods: Diabetic patients with DPN were randomized into groups receiving combination therapy or pregabalin alone for 4 weeks. Pain intensity, gene expression and quality of life were assessed.Results: Combination therapy significantly reduced pain, improved quality of life and upregulated PPARγ and Akt genes compared with monotherapy.Conclusion: Pregabalin and duloxetine combination therapy in DPN led to PPARγ mRNA upregulation and negative correlation of Akt gene expression with pain scores. This combination therapy effectively reduced pain and improved quality of life.Clinical Trial Registration: CTRI/2021/02/031068.

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Combining medicines to reduce nerve pain in diabetic patientsWhat is this article about? People with diabetes often have nerve pain called diabetic peripheral neuropathy (DPN). Some medicines like pregabalin and duloxetine help, but are not enough. This study tested if using both medicines together works better than using just pregabalin. The study also looked at how these medicines affect certain genes.What were the results? Patients with DPN took either both medicines or just pregabalin for 4 weeks. The combined treatment reduced pain, improved life quality and affected certain genes.What do the results of the study mean? Using pregabalin and duloxetine together can reduce DPN pain more effectively. This offers hope for better treatment options.

Asunto(s)

Analgésicos , Neuropatías Diabéticas , Quimioterapia Combinada , Clorhidrato de Duloxetina , PPAR gamma , Pregabalina , Clorhidrato de Duloxetina/administración & dosificación , Humanos , Pregabalina/administración & dosificación , Pregabalina/farmacología , Neuropatías Diabéticas/tratamiento farmacológico , Masculino , Persona de Mediana Edad , Femenino , Analgésicos/administración & dosificación , Analgésicos/farmacología , PPAR gamma/genética , Anciano , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-akt/genética , Neuralgia/tratamiento farmacológico , Neuralgia/genética , Calidad de Vida , Adulto , Dimensión del Dolor

RESUMEN

The information provided from the papers reviewed here about the role of epigenetics in chronic craniofacial neuropathic pain is critically important because epigenetic dysregulation during the development and maintenance of chronic neuropathic pain is not yet well characterized, particularly for craniofacial pain. We have noted that gene expression changes reported vary depending on the nerve injury model and the reported sample collection time point. At a truly chronic timepoint of 10 weeks in our model of chronic neuropathic pain, functional groupings of genes examined include those potentially contributing to anti-inflammation, nerve repair/regeneration, and nociception. Genes altered after treatment with the epigenetic modulator LMK235 are discussed. All of these differentials are key in working toward the development of diagnosis-targeted therapeutics and likely for the timing of when the treatment is provided. The emphasis on the relevance of time post-injury is reiterated here.

Asunto(s)

Epigénesis Genética , Histona Desacetilasas , Neuralgia , Neuralgia/genética , Animales , Humanos , Histona Desacetilasas/genética , Histona Desacetilasas/metabolismo , Dolor Crónico/genética , Dolor Facial/genética

RESUMEN

BACKGROUND: Neuropathic pain (NP) is a challenging health condition owing to its complex nature and associated multiple etiologies. The occurrence of NP involves the abnormal activity of neurons mediated by oxidative stress (OS). Previous research has demonstrated that m6A methylation plays a role in the regulatory pathway of NP. This study aimed to investigate the specific molecular pathways through which m6A methylation modifiers alleviate NP. METHODS: For this purpose, an NO rat model was developed via spared nerve injury (SNI), followed by quantifying the animal's pain assessment via paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). The OS in SNI rats was evaluated by measuring reactive oxygen species, superoxide dismutase, and catalase (CAT) in spinal cord tissues. Moreover, quantitative-real-time polymerase chain reaction and western blot analysis were employed for detecting fat mass and obesity-associated (FTO) and GPR177 levels, while m6A levels of GPR117 were analyzed via MeRIP. RESULTS: The results indicated an enhanced OS with highly expressed FTO in spinal cord tissue samples, where knocking down Fto effectively relieved NP and OS in SNI rats. Mechanistic investigations revealed that Fto-mediated reduction of Grp177 m6A modification was involved in the WNT5a/TRPV1 axis-mediated OS remission of NP. Moreover, in vitro experiment results indicated that YTHDF2 was an important m6A methylated reading protein for this process. CONCLUSIONS: Fto silencing leads to increased m6A methylation of Grp177 through a YTHDF2-dependent mechanism, resulting in decreased Grp177 stability and ultimately reducing NP in rats by OS suppression.

Asunto(s)

Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato , Neuralgia , Estrés Oxidativo , Receptores Acoplados a Proteínas G , Animales , Neuralgia/metabolismo , Neuralgia/genética , Neuralgia/etiología , Ratas , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/metabolismo , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/genética , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/genética , Masculino , Modelos Animales de Enfermedad , Ratas Sprague-Dawley , Silenciador del Gen , Metilación , Adenosina/metabolismo , Adenosina/análogos & derivados , Médula Espinal/metabolismo , Médula Espinal/patología

RESUMEN

Small-Fiber Neuropathy (SFN) is a disorder of the peripheral nervous system, characterised by neuropathic pain; approximately 11% of cases are linked to variants in Voltage-Gated Sodium Channels (VGSCs). This study aims to broaden the genetic knowledge on painful SFN by applying Whole-Exome Sequencing (WES) in Early-Onset (EO) cases. A total of 88 patients from Italy (n = 52) and the Netherlands (n = 36), with a disease onset at age ≤ 45 years old and a Pain Numerical Rating Score ≥ 4, were recruited. After variant filtering and classification, WES analysis identified 142 potentially causative variants in 93 genes; 8 are Pathogenic, 15 are Likely Pathogenic, and 119 are Variants of Uncertain Significance. Notably, an enrichment of variants in transient receptor potential genes was observed, suggesting their role in pain modulation alongside VGSCs. A pathway analysis performed by comparing EO cases with 40 Italian healthy controls found enriched mutated genes in the "Nicotinic acetylcholine receptor signaling pathway". Targeting this pathway with non-opioid drugs could offer novel therapeutic avenues for painful SFN. Additionally, with this study we demonstrated that employing a gene panel of reported mutated genes could serve as an initial screening tool for SFN in genetic studies, enhancing clinical diagnostics.

Asunto(s)

Edad de Inicio , Secuenciación del Exoma , Neuropatía de Fibras Pequeñas , Humanos , Femenino , Masculino , Adulto , Persona de Mediana Edad , Neuropatía de Fibras Pequeñas/genética , Neuralgia/genética , Mutación , Predisposición Genética a la Enfermedad , Italia , Adulto Joven , Adolescente , Países Bajos

RESUMEN

Neurological pain (NP) is always accompanied by symptoms of depression, which seriously affects physical and mental health. In this study, we identified the common hub genes (Co-hub genes) and related immune cells of NP and major depressive disorder (MDD) to determine whether they have common pathological and molecular mechanisms. NP and MDD expression data was downloaded from the Gene Expression Omnibus (GEO) database. Common differentially expressed genes (Co-DEGs) for NP and MDD were extracted and the hub genes and hub nodes were mined. Co-DEGs, hub genes, and hub nodes were analyzed for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Finally, the hub nodes, and genes were analyzed to obtain Co-hub genes. We plotted Receiver operating characteristic (ROC) curves to evaluate the diagnostic impact of the Co-hub genes on MDD and NP. We also identified the immune-infiltrating cell component by ssGSEA and analyzed the relationship. For the GO and KEGG enrichment analyses, 93 Co-DEGs were associated with biological processes (BP), such as fibrinolysis, cell composition (CC), such as tertiary granules, and pathways, such as complement, and coagulation cascades. A differential gene expression analysis revealed significant differences between the Co-hub genes ANGPT2, MMP9, PLAU, and TIMP2. There was some accuracy in the diagnosis of NP based on the expression of ANGPT2 and MMP9. Analysis of differences in the immune cell components indicated an abundance of activated dendritic cells, effector memory CD8+ T cells, memory B cells, and regulatory T cells in both groups, which were statistically significant. In summary, we identified 6 Co-hub genes and 4 immune cell types related to NP and MDD. Further studies are needed to determine the role of these genes and immune cells as potential diagnostic markers or therapeutic targets in NP and MDD.

Asunto(s)

Biología Computacional , Trastorno Depresivo Mayor , Biología de Sistemas , Humanos , Trastorno Depresivo Mayor/genética , Biología Computacional/métodos , Perfilación de la Expresión Génica , Neuralgia/genética , Neuralgia/metabolismo , Redes Reguladoras de Genes , Ontología de Genes , Mapas de Interacción de Proteínas/genética , Bases de Datos Genéticas

RESUMEN

This study investigated the time course of gene expression changes during the progression of persistent painful neuropathy caused by paclitaxel (PTX) in male and female mouse hindpaws and dorsal root ganglia (DRG). Bulk RNA-seq was used to examine these gene expression changes at 1, 16, and 31 days post-last PTX. At these time points, differentially expressed genes (DEGs) were predominantly related to the reduction or increase in epithelial, skin, bone, and muscle development and to angiogenesis, myelination, axonogenesis, and neurogenesis. These processes are accompanied by the regulation of DEGs related to the cytoskeleton, extracellular matrix organization, and cellular energy production. This gene plasticity during the progression of persistent painful neuropathy could be interpreted as a biological process linked to tissue regeneration/degeneration. In contrast, gene plasticity related to immune processes was minimal at 1-31 days after PTX. It was also noted that despite similarities in biological processes and pain chronicity between males and females, specific DEGs differed dramatically according to sex. The main conclusions of this study are that gene expression plasticity in hindpaw and DRG during PTX neuropathy progression similar to tissue regeneration and degeneration, minimally affects immune system processes and is heavily sex-dependent at the individual gene level.

Asunto(s)

Ganglios Espinales , Paclitaxel , Animales , Femenino , Masculino , Ratones , Ganglios Espinales/metabolismo , Ganglios Espinales/efectos de los fármacos , Paclitaxel/efectos adversos , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Enfermedades del Sistema Nervioso Periférico/genética , Regeneración Nerviosa/efectos de los fármacos , Neuralgia/inducido químicamente , Neuralgia/genética , Transcriptoma , Dolor

RESUMEN

Peripheral nerve injury-induced neuronal hyperactivity in the dorsal root ganglion (DRG) participates in neuropathic pain. The calcium-activated potassium channel subfamily N member 1 (KCNN1) mediates action potential afterhyperpolarization (AHP) and gates neuronal excitability. However, the specific contribution of DRG KCNN1 to neuropathic pain is not yet clear. We report that chronic constriction injury (CCI) of the unilateral sciatic nerve or unilateral ligation of the fourth lumbar nerve produced the downregulation of Kcnn1 mRNA and KCNN1 protein in the injured DRG. This downregulation was partially attributed to a decrease in DRG estrogen-related receptor gamma (ESRRG), a transcription factor, which led to reduced binding to the Kcnn1 promoter. Rescuing this downregulation prevented CCI-induced decreases in total potassium voltage currents and AHP currents, reduced excitability in the injured DRG neurons, and alleviated CCI-induced development and maintenance of nociceptive hypersensitivities, without affecting locomotor function and acute pain. Mimicking the CCI-induced DRG KCNN1 downregulation resulted in augmented responses to mechanical, heat, and cold stimuli in naive mice. Our findings indicate that ESRRG-controlled downregulation of DRG KCNN1 is likely essential for the development and maintenance of neuropathic pain. Thus, KCNN1 may serve as a potential target for managing this disorder.

Asunto(s)

Regulación hacia Abajo , Ganglios Espinales , Neuralgia , Células Receptoras Sensoriales , Animales , Masculino , Ratones , Potenciales de Acción , Modelos Animales de Enfermedad , Ganglios Espinales/metabolismo , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/metabolismo , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/genética , Ratones Endogámicos C57BL , Neuralgia/metabolismo , Neuralgia/genética , Traumatismos de los Nervios Periféricos/metabolismo , Traumatismos de los Nervios Periféricos/genética , Nervio Ciático/lesiones , Nervio Ciático/metabolismo , Células Receptoras Sensoriales/metabolismo

RESUMEN

OBJECTIVE: To identify the characteristics of pain syndrome in patients with schwannomas depending on genetic predisposition. MATERIAL AND METHODS: The study included 46 patients with peripheral, spinal and intracranial schwannomas, corresponding to the schwannomatosis phenotype according to the 2022 clinical criteria. All patients underwent sequencing of the LZRT1, Nf2 and SMARCB1 and a copy number study in the NF2. RESULTS: The most severe widespread pain was observed in patients with pathogenic LZRT1 variants, while patients with mosaic variants may not even have local tumor-related pain. Patients with SMARCB1variants may have no pain or have localized pain that responds well to surgical treatment. CONCLUSION: Further studies of the molecular features of schwannomatosis and driver mutations in the pathogenesis of pain are necessary to improve the effectiveness of pain therapy in this group of patients. Schwannomatosis is a disease from the group of neurofibromatosis, manifested by the development of multiple schwannomas. Neuropathic pain is one of the main symptoms characteristic of peripheral schwannomas, however, the severity and prevalence of the pain syndrome does not always correlate with the location of the tumors. According to modern concepts, the key factors influencing the characteristics of the pain syndrome are the target gene and the type of pathogenic variant. The most severe widespread pain is observed in patients with pathogenic variants in the LZRT1 gene, while patients with mosaic variants may not even have local pain associated with tumors. Patients with variants in SMARCB1 may have no pain or localized pain that responds well to surgical treatment.

Asunto(s)

Neurilemoma , Neurofibromatosis , Proteína SMARCB1 , Humanos , Neurilemoma/genética , Neurilemoma/complicaciones , Neurilemoma/diagnóstico , Neurofibromatosis/complicaciones , Neurofibromatosis/genética , Masculino , Femenino , Adulto , Proteína SMARCB1/genética , Persona de Mediana Edad , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/complicaciones , Neurofibromina 2/genética , Factores de Transcripción/genética , Mutación , Neuralgia/genética , Neuralgia/etiología , Neuralgia/diagnóstico , Predisposición Genética a la Enfermedad , Adulto Joven

RESUMEN

Neuroplasticity in the amygdala and its central nucleus (CeA) is linked to pain modulation and pain behaviors, but cellular mechanisms are not well understood. Here, we addressed the role of small-conductance Ca2+-activated potassium (SK) channels in pain-related amygdala plasticity. The facilitatory effects of the intra-CeA application of an SK channel blocker (apamin) on the pain behaviors of control rats were lost in a neuropathic pain model, whereas an SK channel activator (NS309) inhibited pain behaviors in neuropathic rats but not in sham controls, suggesting the loss of the inhibitory behavioral effects of amygdala SK channels. Brain slice electrophysiology found hyperexcitability of CeA neurons in the neuropathic pain condition due to the loss of SK channel-mediated medium afterhyperpolarization (mAHP), which was accompanied by decreased SK2 channel protein and mRNA expression, consistent with a pretranscriptional mechanisms. The underlying mechanisms involved the epigenetic silencing of the SK2 gene due to the increased DNA methylation of the CpG island of the SK2 promoter region and the change in methylated CpG sites in the CeA in neuropathic pain. This study identified the epigenetic dysregulation of SK channels in the amygdala (CeA) as a novel mechanism of neuropathic pain-related plasticity and behavior that could be targeted to control abnormally enhanced amygdala activity and chronic neuropathic pain.

Asunto(s)

Amígdala del Cerebelo , Epigénesis Genética , Neuralgia , Canales de Potasio de Pequeña Conductancia Activados por el Calcio , Animales , Masculino , Ratas , Amígdala del Cerebelo/metabolismo , Amígdala del Cerebelo/fisiopatología , Conducta Animal/efectos de los fármacos , Metilación de ADN/genética , Neuralgia/metabolismo , Neuralgia/genética , Neuralgia/fisiopatología , Neuronas/metabolismo , Ratas Sprague-Dawley , Canales de Potasio de Pequeña Conductancia Activados por el Calcio/metabolismo , Canales de Potasio de Pequeña Conductancia Activados por el Calcio/genética

RESUMEN

Diabetic peripheral neuropathy (DPN) is a common complication of type 2 diabetes mellitus (T2DM) that causes peripheral and autonomic nervous system dysfunction. Dysregulation of miRNAs plays a crucial role in DPN development. However, the role of miR-503-5p in DPN remains unknown. Herein, T2DM mice (db/db) were used as a DPN model in vivo, and astrocytes isolated from db/db mice were induced with high glucose levels as a DPN model in vitro. MiR-503-5p expression was analyzed using qRT-PCR. GFAP, MCP-1, and SEPT9 protein levels were analyzed using western blotting and immunofluorescence. Luciferase assays were performed to investigate the interaction between miR-503-5p and SEPT9. We found that miR-503-5p expression decreased in the spinal cord of DPN model mice and astrocytes treated with high glucose (HG). The db/db mice displayed higher body weight and blood glucose, lower mechanical withdrawal threshold and thermal withdrawal latency, and higher GFAP and MCP-1 protein levels than db/m mice. However, tail vein injection of agomiR-503-5p remarkably reversed these parameters, whereas antigomiR-503-5p enhanced them. HG markedly facilitated GFAP and MCP-1 protein expression in astrocytes, whereas miR-503-5p mimic or inhibitor transfection markedly blocked or elevated GFAP and MCP-1 protein expression, respectively, in astrocytes with HG. SEPT9 was a target of miR-503-5p. In addition, SEPT9 protein levels were found to be elevated in db/db mice and astrocytes treated with HG. Treatment with agomiR-503-5p and miR-503-5p mimic was able to reduce SEPT9 protein levels, whereas treatment with antigomiR-503-5p and miR-503-5p inhibitor led to inhibition of the protein. Furthermore, SEPT9 overexpression suppressed the depressing effect of miR-503-5p overexpression in astrocytes subjected to HG doses. In conclusion, miR-503-5p was found to alleviate peripheral neuropathy-induced neuropathic pain in T2DM mice by regulating SEPT9 expression.

Asunto(s)

Astrocitos , Diabetes Mellitus Tipo 2 , Neuropatías Diabéticas , MicroARNs , Septinas , Animales , Masculino , Ratones , Astrocitos/metabolismo , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/genética , Neuropatías Diabéticas/metabolismo , Neuropatías Diabéticas/genética , Neuropatías Diabéticas/etiología , Modelos Animales de Enfermedad , MicroARNs/genética , MicroARNs/metabolismo , Neuralgia/metabolismo , Neuralgia/genética , Neuralgia/etiología , Septinas/genética , Septinas/metabolismo

RESUMEN

BACKGROUND: The activated microglia have been reported as pillar factors in neuropathic pain (NP) pathology, but the molecules driving pain-inducible microglial activation require further exploration. In this study, we investigated the effect of dorsal root ganglion (DRG)-derived exosomes (Exo) on microglial activation and the related mechanism. METHODS: A mouse model of NP was generated by spinal nerve ligation (SNL), and DRG-derived Exo were extracted. The effects of DRG-Exo on NP and microglial activation in SNL mice were evaluated using behavioral tests, HE staining, immunofluorescence, and western blot. Next, the differentially enriched microRNAs (miRNAs) in DRG-Exo-treated microglia were analyzed using microarrays. RT-qPCR, RNA pull-down, dual-luciferase reporter assay, and immunofluorescence were conducted to verify the binding relation between miR-16-5p and HECTD1. Finally, the effects of ubiquitination modification of HSP90 by HECTD1 on NP progression and microglial activation were investigated by Co-IP, western blot, immunofluorescence assays, and rescue experiments. RESULTS: DRG-Exo aggravated NP resulting from SNL in mice, promoted the activation of microglia in DRG, and increased neuroinflammation. miR-16-5p knockdown in DRG-Exo alleviated the stimulating effects of DRG-Exo on NP and microglial activation. DRG-Exo regulated the ubiquitination of HSP90 through the interaction between miR-16-5p and HECTD1. Ubiquitination alteration of HSP90 was involved in microglial activation during NP. CONCLUSIONS: miR-16-5p shuttled by DRG-Exo regulated the ubiquitination of HSP90 by interacting with HECTD1, thereby contributing to the microglial activation in NP.

Asunto(s)

Exosomas , Ganglios Espinales , Proteínas HSP90 de Choque Térmico , MicroARNs , Microglía , Neuralgia , Animales , Masculino , Ratones , Modelos Animales de Enfermedad , Exosomas/metabolismo , Ganglios Espinales/metabolismo , Proteínas HSP90 de Choque Térmico/metabolismo , Ratones Endogámicos C57BL , Microglía/metabolismo , MicroARNs/metabolismo , MicroARNs/genética , Neuralgia/metabolismo , Neuralgia/genética , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitina-Proteína Ligasas/genética

RESUMEN

Bortezomib-induced neuropathic pain (BINP) poses a challenge in multiple myeloma (MM) treatment. Genetic factors play a key role in BINP susceptibility, but research has predominantly focused on Caucasian populations. This research explored novel genetic risk loci and pathways associated with BINP development in Korean MM patients while evaluating the reproducibility of variants from Caucasians. Clinical data and buffy coat samples from 185 MM patients on bortezomib were collected. The cohort was split into discovery and validation cohorts through random stratification of clinical risk factors for BINP. Genome-wide association study was performed on the discovery cohort (n = 74) with Infinium Global Screening Array-24 v3.0 BeadChip (654,027 single nucleotide polymorphism [SNPs]). Relevant biological pathways were identified using the pathway scoring algorithm. The top 20 SNPs were validated in the validation cohort (n = 111). Previously reported SNPs were validated in the entire cohort (n = 185). Pathway analysis of the genome-wide association study results identified 31 relevant pathways, including immune systems and endosomal vacuolar pathways. Among the top 20 SNPs from the discovery cohort, 16 were replicated, which included intronic variants in ASIC2 and SMOC2, recently implicated in nociception, as well as intergenic variants or long noncoding RNAs. None of the 17 previously reported SNPs remained significant in our cohort (rs2274578, P = .085). This study represents the first investigation of novel genetic loci and biological pathways associated with BINP occurrence. Our findings, in conjunction with existing Caucasian studies, expand the understanding of personalized risk prediction and disease mechanisms. PERSPECTIVE: This article is the first to explore novel genetic loci and pathways linked to BINP in Korean MM patients, offering novel insights beyond the existing research focused on Caucasian populations into personalized risk assessment and therapeutic strategies of BINP.

Asunto(s)

Bortezomib , Estudio de Asociación del Genoma Completo , Neuralgia , Polimorfismo de Nucleótido Simple , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Antineoplásicos/efectos adversos , Bortezomib/efectos adversos , Estudios de Cohortes , Predisposición Genética a la Enfermedad , Mieloma Múltiple/genética , Mieloma Múltiple/tratamiento farmacológico , Neuralgia/genética , Neuralgia/inducido químicamente , República de Corea , Factores de Riesgo , Pueblos del Este de Asia/genética

RESUMEN

This study reports that targeting intrinsically disordered regions of the voltage-gated sodium channel 1.7 (NaV1.7) protein facilitates discovery of sodium channel inhibitory peptide aptamers (NaViPA) for adeno-associated virus-mediated (AAV-mediated), sensory neuron-specific analgesia. A multipronged inhibition of INa1.7, INa1.6, INa1.3, and INa1.1 - but not INa1.5 and INa1.8 - was found for a prototype and named NaViPA1, which was derived from the NaV1.7 intracellular loop 1, and is conserved among the TTXs NaV subtypes. NaViPA1 expression in primary sensory neurons (PSNs) of dorsal root ganglia (DRG) produced significant inhibition of TTXs INa but not TTXr INa. DRG injection of AAV6-encoded NaViPA1 significantly attenuated evoked and spontaneous pain behaviors in both male and female rats with neuropathic pain induced by tibial nerve injury (TNI). Whole-cell current clamp of the PSNs showed that NaViPA1 expression normalized PSN excitability in TNI rats, suggesting that NaViPA1 attenuated pain by reversal of injury-induced neuronal hypersensitivity. IHC revealed efficient NaViPA1 expression restricted in PSNs and their central and peripheral terminals, indicating PSN-restricted AAV biodistribution. Inhibition of sodium channels by NaViPA1 was replicated in the human iPSC-derived sensory neurons. These results summate that NaViPA1 is a promising analgesic lead that, combined with AAV-mediated PSN-specific block of multiple TTXs NaVs, has potential as a peripheral nerve-restricted analgesic therapeutic.

Asunto(s)

Dependovirus , Canal de Sodio Activado por Voltaje NAV1.7 , Células Receptoras Sensoriales , Animales , Ratas , Dependovirus/genética , Células Receptoras Sensoriales/metabolismo , Masculino , Humanos , Femenino , Canal de Sodio Activado por Voltaje NAV1.7/metabolismo , Canal de Sodio Activado por Voltaje NAV1.7/genética , Ganglios Espinales/metabolismo , Ratas Sprague-Dawley , Neuralgia/metabolismo , Neuralgia/genética , Neuralgia/tratamiento farmacológico , Analgesia

RESUMEN

Although the molecular mechanisms of chronic pain have been extensively studied, a global picture of alternatively spliced genes and events in the peripheral and central nervous systems of chronic pain is poorly understood. The current study analyzed the changing pattern of alternative splicing (AS) in mouse brain, dorsal root ganglion, and spinal cord tissue under inflammatory and neuropathic pain. In total, we identified 6495 differentially alternatively spliced (DAS) genes. The molecular functions of shared DAS genes between these two models are mainly enriched in calcium signaling pathways, synapse organization, axon regeneration, and neurodegeneration disease. Additionally, we identified 509 DAS in differentially expressed genes (DEGs) shared by these two models, accounting for a small proportion of total DEGs. Our findings supported the hypothesis that the AS has an independent regulation pattern different from transcriptional regulation. Taken together, these findings indicate that AS is one of the important molecular mechanisms of chronic pain in mammals. This study presents a global description of AS profile changes in the full path of neuropathic and inflammatory pain models, providing new insights into the underlying mechanisms of chronic pain and guiding genomic clinical diagnosis methods and rational medication.

Asunto(s)

Empalme Alternativo , Perfilación de la Expresión Génica , Inflamación , Ratones Endogámicos C57BL , Neuralgia , Transcriptoma , Animales , Neuralgia/genética , Neuralgia/metabolismo , Empalme Alternativo/genética , Inflamación/genética , Transcriptoma/genética , Masculino , Ganglios Espinales/metabolismo , Ratones , Médula Espinal/metabolismo , Médula Espinal/patología , Regulación de la Expresión Génica , Modelos Animales de Enfermedad

RESUMEN

Cancer patients undergoing treatment with antineoplastic drugs often experience chemotherapy-induced neuropathic pain (CINP), and the therapeutic options for managing CINP are limited. Here, we show that systemic paclitaxel administration upregulates the expression of neurotrophin-3 (Nt3) mRNA and NT3 protein in the neurons of dorsal root ganglia (DRG), but not in the spinal cord. Blocking NT3 upregulation attenuates paclitaxel-induced mechanical, heat, and cold nociceptive hypersensitivities and spontaneous pain without altering acute pain and locomotor activity in male and female mice. Conversely, mimicking this increase produces enhanced responses to mechanical, heat, and cold stimuli and spontaneous pain in naive male and female mice. Mechanistically, NT3 triggers tropomyosin receptor kinase C (TrkC) activation and participates in the paclitaxel-induced increases of C-C chemokine ligand 2 (Ccl2) mRNA and CCL2 protein in the DRG. Given that CCL2 is an endogenous initiator of CINP and that Nt3 mRNA co-expresses with TrkC and Ccl2 mRNAs in DRG neurons, NT3 likely contributes to CINP through TrkC-mediated activation of the Ccl2 gene in DRG neurons. NT3 may be thus a potential target for CINP treatment.

Asunto(s)

Quimiocina CCL2 , Ganglios Espinales , Neuralgia , Neuronas , Neurotrofina 3 , Paclitaxel , Receptor trkC , Animales , Femenino , Masculino , Ratones , Antineoplásicos/efectos adversos , Quimiocina CCL2/metabolismo , Quimiocina CCL2/genética , Ganglios Espinales/metabolismo , Ganglios Espinales/efectos de los fármacos , Neuralgia/inducido químicamente , Neuralgia/metabolismo , Neuralgia/genética , Neuronas/metabolismo , Neuronas/efectos de los fármacos , Neurotrofina 3/metabolismo , Neurotrofina 3/genética , Paclitaxel/efectos adversos , Paclitaxel/farmacología , Receptor trkC/metabolismo , Receptor trkC/genética , ARN Mensajero/metabolismo , ARN Mensajero/genética , Factores de Crecimiento Nervioso/genética , Factores de Crecimiento Nervioso/metabolismo