RESUMEN

Background: IL-1ß plays a critical role in the pathophysiology of neuroinflammation. The presence of cleaved IL-1ß (cIL-1ß) in the neurons of the dorsal root ganglion (DRG) implicates its function in biological signaling arising from the sensory neuron. This study was conducted to analyze the role of IL-1ß in nociceptive transduction after tissue injury. Methods: A plantar incision was made in C57BL/6 mice, following which immunohistochemistry and RNA scope in situ hybridization were performed at various time points to analyze cIL-1ß, caspase-1, and IL-1 receptor 1 (IL-1R1) expression in the DRG. The effect of intrathecal administration of a caspase-1 inhibitor or regional anesthesia using local anesthetics on cIL-1ß expression and pain hypersensitivity was analyzed by immunohistochemistry and behavioral analysis. ERK phosphorylation was also analyzed to investigate the effect of IL-1ß on the activity of spinal dorsal horn neurons. Results: cIL-1ß expression was significantly increased in caspase-1-positive DRG neurons 5 min after the plantar incision. Intrathecal caspase-1 inhibitor treatment inhibited IL-1ß cleavage and pain hypersensitivity after the plantar incision. IL-1R1 was also detected in the DRG neurons, although the majority of IL-1R1-expressing neurons lacked cIL-1ß expression. Regional anesthesia using local anesthetics prevented cIL-1ß processing. Plantar incision-induced phosphorylation of ERK was inhibited by the caspase-1 inhibitor. Conclusion: IL-1ß in the DRG neuron undergoes rapid cleavage in response to tissue injury in an activity-dependent manner. Cleaved IL-1ß causes injury-induced functional activation of sensory neurons and pain hypersensitivity. IL-1ß in the primary afferent neurons is involved in physiological nociceptive signal transduction.

Asunto(s)

Ganglios Espinales , Interleucina-1beta , Ratones Endogámicos C57BL , Animales , Interleucina-1beta/metabolismo , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Masculino , Caspasa 1/metabolismo , Hiperalgesia/metabolismo , Neuronas/metabolismo , Neuronas/patología , Neuronas/efectos de los fármacos , Ratones , Fosforilación/efectos de los fármacos , Receptores Tipo I de Interleucina-1/metabolismo , Células del Asta Posterior/metabolismo , Células del Asta Posterior/efectos de los fármacos , Quinasas MAP Reguladas por Señal Extracelular/metabolismo

RESUMEN

Bone cancer pain (BCP) represents a prevalent symptom among cancer patients with bone metastases, yet its underlying mechanisms remain elusive. This study investigated the transcriptional regulation mechanism of Kv7(KCNQ)/M potassium channels in DRG neurons and its involvement in the development of BCP in rats. We show that HDAC2-mediated transcriptional repression of kcnq2/kcnq3 genes, which encode Kv7(KCNQ)/M potassium channels in dorsal root ganglion (DRG), contributes to the sensitization of DRG neurons and the pathogenesis of BCP in rats. Also, HDAC2 requires the formation of a corepressor complex with MeCP2 and Sin3A to execute transcriptional regulation of kcnq2/kcnq3 genes. Moreover, EREG is identified as an upstream signal molecule for HDAC2-mediated kcnq2/kcnq3 genes transcription repression. Activation of EREG/EGFR-ERK-Runx1 signaling, followed by the induction of HDAC2-mediated transcriptional repression of kcnq2/kcnq3 genes in DRG neurons, leads to neuronal hyperexcitability and pain hypersensitivity in tumor-bearing rats. Consequently, the activation of EREG/EGFR-ERK-Runx1 signaling, along with the subsequent transcriptional repression of kcnq2/kcnq3 genes by HDAC2 in DRG neurons, underlies the sensitization of DRG neurons and the pathogenesis of BCP in rats. These findings uncover a potentially targetable mechanism contributing to bone metastasis-associated pain in cancer patients.

Asunto(s)

Neoplasias Óseas , Dolor en Cáncer , Receptores ErbB , Ganglios Espinales , Histona Desacetilasa 2 , Canal de Potasio KCNQ2 , Animales , Histona Desacetilasa 2/metabolismo , Histona Desacetilasa 2/genética , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ2/metabolismo , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Neoplasias Óseas/genética , Neoplasias Óseas/metabolismo , Neoplasias Óseas/secundario , Neoplasias Óseas/patología , Ratas , Dolor en Cáncer/genética , Dolor en Cáncer/metabolismo , Dolor en Cáncer/patología , Receptores ErbB/metabolismo , Receptores ErbB/genética , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ3/metabolismo , Transcripción Genética , Proteína 2 de Unión a Metil-CpG/genética , Proteína 2 de Unión a Metil-CpG/metabolismo , Complejo Correpresor Histona Desacetilasa y Sin3/genética , Transducción de Señal/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/metabolismo , Humanos , Femenino , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Ratas Sprague-Dawley , Sistema de Señalización de MAP Quinasas/genética

RESUMEN

Endometriosis is an estrogen-dependent inflammatory gynecological disease whose pathogenesis is unclear. C-C motif chemokine ligand 18 (CCL18), a chemokine, is involved in several inflammatory diseases. In this study, we aimed to investigate the role of CCL18 in endometriosis and its underlying mechanisms. Human endometrium and peritoneal fluid were obtained from women with and without endometriosis for molecular studies. The expression level of CCL18 in each tissue sample was examined by RNA sequencing analysis, quantitative PCR analysis and immunohistochemistry staining. The effects of CCL18 on cell migration, tube formation and neurite growth were investigated in vitro using primary endometrial cells, human umbilical vein endothelial cells (HUVECs) and dorsal root ganglion (DRG) neurons, respectively. Moreover, the development of endometriosis in mice was studied in vivo by blocking CCL18. CCL18 was shown to be overexpressed in endometrial foci and peritoneal fluid in women with endometriosis and was positively correlated with endometriosis pain. In vitro, CCL18 promoted the migration of ectopic endometrial cells, tube formation of HUVECs, and nerve outgrowth of DRG neurons. More importantly, inhibition of CCL18 significantly suppressed lesion development, angiogenesis, and nerve infiltration in a mouse model of endometriosis. In conclusion, CCL18 may play a role in the progression of endometriosis by increasing endometrial cell migration and promoting neuroangiogenesis.

Asunto(s)

Movimiento Celular , Quimiocinas CC , Endometriosis , Endometrio , Células Endoteliales de la Vena Umbilical Humana , Neovascularización Patológica , Endometriosis/metabolismo , Endometriosis/patología , Femenino , Humanos , Animales , Endometrio/metabolismo , Endometrio/patología , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Ratones , Neovascularización Patológica/metabolismo , Neovascularización Patológica/patología , Quimiocinas CC/metabolismo , Adulto , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Líquido Ascítico/metabolismo , Líquido Ascítico/patología , Ratones Endogámicos C57BL

RESUMEN

A large portion of neuropathic pain suffering patients may also concurrently experience neuropathic itch, with a negative impact on the quality of life. The limited understanding of neuropathic itch and the low efficacy of current anti-itch therapies dictate the urgent need of a better comprehension of molecular mechanisms involved and development of relevant animal models. This study was aimed to characterize the itching phenotype in a model of trauma-induced peripheral neuropathy, the spared nerve injury (SNI), and the molecular events underlying the overlap with the nociceptive behavior. SNI mice developed hyperknesis and spontaneous itch 7-14 days after surgery that was prevented by gabapentin treatment. Itch was associated with pain hypersensitivity, loss of intraepidermal nerve fiber (IENF) density and increased epidermal thickness. In coincidence with the peak of scratching behavior, SNI mice showed a spinal overexpression of IBA1 and GFAP, microglia and astrocyte markers respectively. An increase of the itch neuropeptide B-type natriuretic peptide (BNP) in NeuN+ cells, of its downstream effector interleukin 17 (IL17) along with increased pERK1/2 levels occurred in the spinal cord dorsal horn and DRG. A raise in BNP and IL17 was also detected at skin level. Stimulation of HaCat cells with conditioned medium from BV2-stimulated SH-SY5Y cells produced a dramatic reduction of HaCat cell viability. This study showed that SNI mice might represent a model for neuropathic itch and pain. Collectively, our finding suggest that neuropathic itch might initiate at spinal level, then affecting skin epidermis events, through a glia-mediated neuroinflammation-evoked BNP/IL17 mechanism.

Asunto(s)

Modelos Animales de Enfermedad , Neuralgia , Enfermedades Neuroinflamatorias , Prurito , Animales , Prurito/metabolismo , Prurito/patología , Neuralgia/metabolismo , Neuralgia/etiología , Ratones , Masculino , Enfermedades Neuroinflamatorias/metabolismo , Humanos , Gabapentina/farmacología , Interleucina-17/metabolismo , Ratones Endogámicos C57BL , Ganglios Espinales/metabolismo , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/patología , Células HaCaT , Microglía/metabolismo , Microglía/efectos de los fármacos , Hiperalgesia/metabolismo , Proteínas de Microfilamentos/metabolismo , Asta Dorsal de la Médula Espinal/metabolismo , Asta Dorsal de la Médula Espinal/efectos de los fármacos , Proteínas de Unión al Calcio

RESUMEN

Diabetic peripheral neuropathy (DPN) is caused by several factors, including reactive free oxygen radicals (ROS)-induced excessive Ca2+ influx. Transient receptor potential (TRP) vanilloid 4 (TRPV4) is a member of the Ca2+-permeable TRP superfamily. Resveratrol (RESV) has been extensively utilized in TRP channel regulation due to its pharmacological properties, which include antioxidant and TRP inhibitory effects. The protective function of RESV and the contribution of TRPV4 to streptozotocin (STZ)-induced neuropathic pain in mice are still unclear. Here, we evaluated the effects of RESV through the modulation of TRPV4 on Ca2+ influx, ROS-mediated pain, apoptosis, and oxidative damage in the mouse dorsal root ganglion (DRGs). From the 32 mice, four groups were induced: control, RESV, STZ, and STZ + RESV. We found that the injection of RESV reduced the changes caused by the STZ-induced stimulation of TRPV4, which in turn increased mechanical/thermal neuropathic pain, cytosolic Ca2+ influx, TRPV4 current density, oxidants (lipid peroxidation, mitochondrial ROS, and cytosolic ROS), and apoptotic markers (caspase-3, -8, and -9). The RESV injection also increased the STZ-mediated reduction of viability of DRG and the amounts of glutathione, glutathione peroxidase, vitamin A, ß-carotene, and vitamin E in the brain, erythrocytes, plasma, liver, and kidney. All of these findings suggest that TRPV4 stimulation generates oxidative neurotoxicity, neuropathic pain, and apoptosis in the STZ-induced diabetic mice. On the other hand, neurotoxicity and apoptosis were reduced due to the downregulation of TRPV4 carried out through the RESV injection.

Asunto(s)

Apoptosis , Diabetes Mellitus Experimental , Ganglios Espinales , Neuralgia , Estrés Oxidativo , Resveratrol , Canales Catiónicos TRPV , Animales , Canales Catiónicos TRPV/metabolismo , Apoptosis/efectos de los fármacos , Resveratrol/farmacología , Resveratrol/uso terapéutico , Masculino , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patología , Estrés Oxidativo/efectos de los fármacos , Neuralgia/tratamiento farmacológico , Neuralgia/metabolismo , Neuralgia/patología , Ganglios Espinales/metabolismo , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/patología , Ratones , Calcio/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Estreptozocina/toxicidad , Neuropatías Diabéticas/metabolismo , Neuropatías Diabéticas/tratamiento farmacológico , Neuropatías Diabéticas/patología

RESUMEN

Diabetic peripheral neuropathy (DPN) is a common complication associated with diabetes, and can affect quality of life considerably. Dorsal root ganglion (DRG) plays an important role in the development of DPN. However, the relationship between DRG and the pathogenesis of DPN still lacks a thorough exploration. Besides, a more in-depth understanding of the cell type composition of DRG, and the roles of different cell types in mediating DPN are needed. Here we conducted single-cell RNA-seq (scRNA-seq) for DRG tissues isolated from healthy control and DPN rats. Our results demonstrated DRG includes eight cell-type populations (e.g., neurons, satellite glial cells (SGCs), Schwann cells (SCs), endothelial cells, fibroblasts). In the heterogeneity analyses of cells, six neuron sub-types, three SGC sub-types and three SC sub-types were identified, additionally, biological functions related to cell sub-types were further revealed. Cell communication analysis showed dynamic interactions between neurons, SGCs and SCs. We also found that the aberrantly expressed transcripts in sub-types of neurons, SGCs and SCs with DPN were associated with diabetic neuropathic pain, cell apoptosis, oxidative stress, etc. In conclusion, this study provides a systematic perspective of the cellular composition and interactions of DRG tissues, and suggests that neurons, SGCs and SCs play vital roles in the progression of DPN. Our data may provide a valuable resource for future studies regarding the pathophysiological effect of particular cell type in DPN.

Asunto(s)

Neuropatías Diabéticas , Ganglios Espinales , Perfilación de la Expresión Génica , Células de Schwann , Análisis de la Célula Individual , Animales , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Neuropatías Diabéticas/patología , Neuropatías Diabéticas/genética , Neuropatías Diabéticas/metabolismo , Ratas , Células de Schwann/metabolismo , Células de Schwann/patología , Masculino , Transcriptoma , Neuronas/metabolismo , Neuronas/patología , Ratas Sprague-Dawley , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/patología , Análisis de Expresión Génica de una Sola Célula

RESUMEN

Low back pain, knee osteoarthritis, and cancer patients suffer from chronic pain. Aberrant nerve growth into intervertebral disc, knee, and tumors, are common pathologies that lead to these chronic pain conditions. Axonal dieback induced by capsaicin (Caps) denervation has been FDA-approved to treat painful neuropathies and knee osteoarthritis but with short-term efficacy and discomfort. Herein, we propose to evaluate pyridoxine (Pyr), vincristine sulfate (Vcr) and ionomycin (Imy) as axonal dieback compounds for denervation with potential to alleviate pain. Previous literature suggests Pyr, Vcr, and Imy can cause undesired axonal degeneration, but no previous work has evaluated axonal dieback and cytotoxicity on adult rat dorsal root ganglia (DRG) explants. Thus, we performed axonal dieback screening using adult rat DRG explants in vitro with Caps as a positive control and assessed cytotoxicity. Imy inhibited axonal outgrowth and slowed axonal dieback, while Pyr and Vcr at high concentrations produced significant reduction in axon length and robust axonal dieback within three days. DRGs treated with Caps, Vcr, or Imy had increased DRG cytotoxicity compared to matched controls, but overall cytotoxicity was minimal and at least 88% lower compared to lysed DRGs. Pyr did not lead to any DRG cytotoxicity. Further, neither Pyr nor Vcr triggered intervertebral disc cell death or affected cellular metabolic activity after three days of incubation in vitro. Overall, our findings suggest Pyr and Vcr are not toxic to DRGs and intervertebral disc cells, and there is potential for repurposing these compounds for axonal dieback compounds to cause local denervation and alleviate pain.

Asunto(s)

Axones , Desnervación , Ganglios Espinales , Disco Intervertebral , Animales , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/patología , Ratas , Disco Intervertebral/efectos de los fármacos , Disco Intervertebral/patología , Axones/efectos de los fármacos , Capsaicina/farmacología , Ratas Sprague-Dawley , Masculino , Vincristina/farmacología

RESUMEN

BACKGROUND: Since the 1990s, evidence has accumulated that macrophages promote peripheral nerve regeneration and are required for enhancing regeneration in the conditioning lesion (CL) response. After a sciatic nerve injury, macrophages accumulate in the injury site, the nerve distal to that site, and the axotomized dorsal root ganglia (DRGs). In the peripheral nervous system, as in other tissues, the macrophage response is derived from both resident macrophages and recruited monocyte-derived macrophages (MDMs). Unresolved questions are: at which sites do macrophages enhance nerve regeneration, and is a particular population needed. METHODS: Ccr2 knock-out (KO) and Ccr2gfp/gfp knock-in/KO mice were used to prevent MDM recruitment. Using these strains in a sciatic CL paradigm, we examined the necessity of MDMs and residents for CL-enhanced regeneration in vivo and characterized injury-induced nerve inflammation. CL paradigm variants, including the addition of pharmacological macrophage depletion methods, tested the role of various macrophage populations in initiating or sustaining the CL response. In vivo regeneration, measured from bilateral proximal test lesions (TLs) after 2 d, and macrophages were quantified by immunofluorescent staining. RESULTS: Peripheral CL-enhanced regeneration was equivalent between crush and transection CLs and was sustained for 28 days in both Ccr2 KO and WT mice despite MDM depletion. Similarly, the central CL response measured in dorsal roots was unchanged in Ccr2 KO mice. Macrophages at both the TL and CL, but not between them, stained for the pro-regenerative marker, arginase 1. TL macrophages were primarily CCR2-dependent MDMs and nearly absent in Ccr2 KO and Ccr2gfp/gfp KO mice. However, there were only slightly fewer Arg1+ macrophages in CCR2 null CLs than controls due to resident macrophage compensation. Zymosan injection into an intact WT sciatic nerve recruited Arg1+ macrophages but did not enhance regeneration. Finally, clodronate injection into Ccr2gfp KO CLs dramatically reduced CL macrophages. Combined with the Ccr2gfp KO background, depleting MDMs and TL macrophages, and a transection CL, physically removing the distal nerve environment, nearly all macrophages in the nerve were removed, yet CL-enhanced regeneration was not impaired. CONCLUSIONS: Macrophages in the sciatic nerve are neither necessary nor sufficient to produce a CL response.

Asunto(s)

Macrófagos , Regeneración Nerviosa , Traumatismos de los Nervios Periféricos , Receptores CCR2 , Degeneración Walleriana , Animales , Macrófagos/metabolismo , Macrófagos/patología , Ratones , Regeneración Nerviosa/fisiología , Degeneración Walleriana/patología , Receptores CCR2/metabolismo , Receptores CCR2/genética , Receptores CCR2/deficiencia , Traumatismos de los Nervios Periféricos/patología , Traumatismos de los Nervios Periféricos/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Neuropatía Ciática/patología , Axones/patología , Ratones Transgénicos , Modelos Animales de Enfermedad , Nervio Ciático/lesiones , Nervio Ciático/patología , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo

RESUMEN

Spinal cord injury (SCI) increases the risk of cardiometabolic disorders, including hypertension, dyslipidemia, and insulin resistance. Not only does SCI lead to pathological expansion of adipose tissue, but it also leads to ectopic lipid accumulation in organs integral to glucose and insulin metabolism. The pathophysiological changes that underlie adipose tissue dysfunction after SCI are unknown. Here, we find that SCI exacerbates lipolysis in epididymal white adipose tissue (eWAT). Whereas expression of the α2δ1 subunit of voltage-gated calcium channels increases in calcitonin gene-related peptide-positive dorsal root ganglia neurons that project to eWAT, conditional deletion of the gene encoding α2δ1 in these neurons normalizes eWAT lipolysis after SCI. Furthermore, α2δ1 pharmacological blockade through systemic administration of gabapentin also normalizes eWAT lipolysis after SCI, preventing ectopic lipid accumulation in the liver. Thus, our study provides insight into molecular causes of maladaptive sensory processing in eWAT, facilitating the development of strategies to reduce metabolic and cardiovascular complications after SCI.

Asunto(s)

Tejido Adiposo Blanco , Homeostasis , Lipólisis , Traumatismos de la Médula Espinal , Traumatismos de la Médula Espinal/metabolismo , Traumatismos de la Médula Espinal/patología , Traumatismos de la Médula Espinal/fisiopatología , Animales , Lipólisis/efectos de los fármacos , Masculino , Ratones , Tejido Adiposo Blanco/metabolismo , Plasticidad Neuronal/efectos de los fármacos , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Tejido Adiposo/metabolismo , Ratones Endogámicos C57BL , Neuronas/metabolismo , Neuronas/patología , Péptido Relacionado con Gen de Calcitonina/metabolismo , Péptido Relacionado con Gen de Calcitonina/genética

RESUMEN

Understanding the intricate processes of neuronal growth, degeneration, and neurotoxicity is paramount for unraveling nervous system function and holds significant promise in improving patient outcomes, especially in the context of chemotherapy-induced peripheral neuropathy (CIPN). These processes are influenced by a broad range of entwined events facilitated by chemical, electrical, and mechanical signals. The progress of each process is inherently linked to phenotypic changes in cells. Currently, the primary means of demonstrating morphological changes rely on measurements of neurite outgrowth and axon length. However, conventional techniques for monitoring these processes often require extensive preparation to enable manual or semi-automated measurements. Here, a label-free and non-invasive approach is employed for monitoring neuronal differentiation and degeneration using quantitative phase imaging (QPI). Operating on unlabeled specimens and offering little to no phototoxicity and photobleaching, QPI delivers quantitative maps of optical path length delays that provide an objective measure of cellular morphology and dynamics. This approach enables the visualization and quantification of axon length and other physical properties of dorsal root ganglion (DRG) neuronal cells, allowing greater understanding of neuronal responses to stimuli simulating CIPN conditions. This research paves new avenues for the development of more effective strategies in the clinical management of neurotoxicity.

Asunto(s)

Axones , Diferenciación Celular , Ganglios Espinales , Animales , Ganglios Espinales/patología , Ganglios Espinales/citología , Axones/patología , Neuronas/patología , Humanos , Ratones , Enfermedades del Sistema Nervioso Periférico/patología , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Enfermedades del Sistema Nervioso Periférico/fisiopatología , Imágenes de Fase Cuantitativa

RESUMEN

Peripheral neuropathy (PN) is a severe and frequent complication of obesity, prediabetes, and type 2 diabetes characterized by progressive distal-to-proximal peripheral nerve degeneration. However, a comprehensive understanding of the mechanisms underlying PN, and whether these mechanisms change during PN progression, is currently lacking. Here, gene expression data were obtained from distal (sciatic nerve; SCN) and proximal (dorsal root ganglia; DRG) injury sites of a high-fat diet (HFD)-induced mouse model of obesity/prediabetes at early and late disease stages. Self-organizing map and differentially expressed gene analyses followed by pathway enrichment analysis identified genes and pathways altered across disease stage and injury site. Pathways related to immune response, inflammation, and glucose and lipid metabolism were consistently dysregulated with HFD-induced PN, irrespective of injury site. However, regulation of oxidative stress was unique to the SCN while dysregulated Hippo and Notch signaling were only observed in the DRG. The role of the immune system and inflammation in disease progression was supported by an increase in the percentage of immune cells in the SCN with PN progression. Finally, when comparing these data to transcriptomic signatures from human patients with PN, we observed conserved pathways related to metabolic dysregulation across species, highlighting the translational relevance of our mouse data. Our findings demonstrate that PN is associated with distinct site-specific molecular re-programming in the peripheral nervous system, identifying novel, clinically relevant therapeutic targets.

Asunto(s)

Ganglios Espinales , Perfilación de la Expresión Génica , Ratones Endogámicos C57BL , Estado Prediabético , Nervio Ciático , Animales , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Estado Prediabético/metabolismo , Estado Prediabético/genética , Estado Prediabético/patología , Masculino , Nervio Ciático/metabolismo , Nervio Ciático/lesiones , Nervio Ciático/patología , Ratones , Dieta Alta en Grasa/efectos adversos , Transcriptoma , Humanos , Enfermedades del Sistema Nervioso Periférico/genética , Enfermedades del Sistema Nervioso Periférico/patología , Enfermedades del Sistema Nervioso Periférico/metabolismo

RESUMEN

Background: Loss of Cholinergic Receptor Muscarinic 1 (CHRM1) has been linked to the pathogenesis of Alzheimer's disease (AD). Our recent study found significantly lower CHRM1 protein levels in AD patient cortices, linked to reduced survival. Furthermore, using knockout mice (Chrm1-/-) we demonstrated that deletion of Chrm1 alters cortical mitochondrial structure and function, directly establishing a connection between its loss and mitochondrial dysfunction in the context of AD. While CHRM1's role in the brain has been extensively investigated, its impact on peripheral neurons in AD remains a crucial area of research, especially considering reported declines in peripheral nerve conduction among AD patients. Objective: The objective was to characterize Chrm1 localization and mitochondrial deficits in Chrm1-/- dorsal root ganglion (DRG) neurons. Methods: Recombinant proteins tagged with Green or Red Fluorescent Protein (GFP/RFP) were transiently expressed to investigate the localization of Chrm1 and mitochondria, as well as mitochondrial movement in the neurites of cultured primary mouse DRG neurons, using confocal time-lapse live cell imaging. Transmission electron microscopy was performed to examine the ultrastructure of mitochondria in both wild-type and Chrm1-/- DRGs. Results: Fluorescence imaging revealed colocalization and comigration of N-terminal GFP-tagged Chrm1 and mitochondrial localization signal peptide-tagged RFP-labelled mitochondria in the DRGs neurons. A spectrum of mitochondrial structural abnormalities, including disruption and loss of cristae was observed in 87% neurons in Chrm1-/- DRGs. Conclusions: This study suggests that Chrm1 may be localized in the neuronal mitochondria and loss of Chrm1 in peripheral neurons causes sever mitochondrial structural aberrations resembling AD pathology.

Asunto(s)

Enfermedad de Alzheimer , Humanos , Ratones , Animales , Enfermedad de Alzheimer/patología , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Neuronas/metabolismo , Ratones Noqueados , Mitocondrias/metabolismo , Colinérgicos , Receptor Muscarínico M1/genética , Receptor Muscarínico M1/metabolismo

RESUMEN

Oxaliplatin, a platinum-based chemotherapeutic agent, frequently causes acute and chronic peripheral sensory neuropathy, for which no effective treatment has been established. In particular, chronic neuropathy can persist for years even after treatment completion, thus worsening patients' quality of life. To avoid the development of intractable adverse effects, a predictive biomarker early in treatment is awaited. In this study, we explored extracellular long non-coding RNAs (lncRNAs) released from primary sensory neurons as biomarker candidates for oxaliplatin-induced peripheral neuropathy. Because many human-specific lncRNA genes exist, we induced peripheral sensory neurons from human induced pluripotent stem cells. Oxaliplatin treatment changed the levels of many lncRNAs in extracellular vesicles (EVs) released from cultured primary sensory neurons. Among them, the levels of release of lncRNAs that were considered to be selectively expressed in dorsal root ganglia were correlated with those of lncRNAs in plasma EV obtained from healthy individuals. Several lncRNAs in plasma EVs early after the initiation of treatment showed greater changes in patients who did not develop chronic neuropathy that persisted for more than 1 year than in those who did. Therefore, these extracellular lncRNAs in plasma EVs may represent predictive biomarkers for the development of chronic peripheral neuropathy induced by oxaliplatin.

Asunto(s)

Biomarcadores , Células Madre Pluripotentes Inducidas , Oxaliplatino , Enfermedades del Sistema Nervioso Periférico , ARN Largo no Codificante , Células Receptoras Sensoriales , Oxaliplatino/efectos adversos , Humanos , ARN Largo no Codificante/genética , ARN Largo no Codificante/sangre , Células Madre Pluripotentes Inducidas/metabolismo , Células Receptoras Sensoriales/efectos de los fármacos , Células Receptoras Sensoriales/metabolismo , Biomarcadores/sangre , Biomarcadores/metabolismo , Enfermedades del Sistema Nervioso Periférico/sangre , Enfermedades del Sistema Nervioso Periférico/inducido químicamente , Enfermedades del Sistema Nervioso Periférico/patología , Masculino , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/efectos de los fármacos , Femenino , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Enfermedad Crónica , Persona de Mediana Edad , Células Cultivadas

RESUMEN

Adeno-associated virus (AAV)-based vectors are commonly used for delivering transgenes in gene therapy studies, but they are also known to cause dorsal root ganglia (DRG) and peripheral nerve toxicities in animals. However, the functional implications of these pathologic findings and their time course remain unclear. At 2, 4, 6, and 8 weeks following a single dose of an AAV9 vector carrying human frataxin transgene in rats, non-standard functional assessments, including von Frey filament, electrophysiology, and Rotarod tests, were conducted longitudinally to measure allodynia, nerve conduction velocity, and coordination, respectively. Additionally, DRGs, peripheral nerves, brain and spinal cord were evaluated histologically and circulating neurofilament light chain (NfL) was quantified at 1, 2, 4, and 8 weeks, respectively. At 2 and 4 weeks after dosing, minimal-to-moderate nerve fiber degeneration and neuronal degeneration were observed in the DRGs in some of the AAV9 vector-dosed animals. At 8 weeks, nerve fiber degeneration was observed in DRGs, with or without neuronal degeneration, and in sciatic nerves of all AAV9 vector-dosed animals. NfL values were higher in AAV9 vector-treated animals at weeks 4 and 8 compared with controls. However, there were no significant differences in the three functional endpoints evaluated between the AAV9 vector- and vehicle-dosed animals, or in a longitudinal comparison between baseline (predose), 4, and 8 week values in the AAV9 vector-dose animals. These findings demonstrate that there is no detectable functional consequence to the minimal-to-moderate neurodegeneration observed with our AAV9 vector treatment in rats, suggesting a functional tolerance or reserve for loss of DRG neurons after systemic administration of AAV9 vector.

Asunto(s)

Ganglios Espinales , Enfermedades del Sistema Nervioso Periférico , Humanos , Ratas , Animales , Ganglios Espinales/patología , Fibras Nerviosas , Nervio Ciático , Enfermedades del Sistema Nervioso Periférico/genética , Enfermedades del Sistema Nervioso Periférico/patología , Neuronas

RESUMEN

Peripheral nerve injury (PNI) usually has a poor effect on functional recovery and severely declines the patient's quality of life. Our prior findings indicated that hypoxia remarkably promoted nerve regeneration of rats with sciatic nerve transection. However, the underlying molecular mechanisms of hypoxia in functional recovery of PNI still remain elusive. In this research, we tried to explain the functional roles and mechanisms of hypoxia and the hypoxia-inducible factor-1α (HIF-1α) in PNI. Our results indicated that hypoxia promoted proliferation and migration of dorsal root ganglia (DRG) and increased the expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Mechanistically, hypoxia suppressed ferroptosis through activating HIF-1α in DRG neurons. Gain and loss of function studies were performed to evaluate the regulatory roles of HIF-1α in ferroptosis and neuron recovery. The results revealed that up-regulation of HIF-1α enhanced the expression of solute carrier family membrane 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) and increased the contents of cysteine and glutathione, while inhibiting the accumulation of reactive oxygen species (ROS). Our findings provided novel light on the mechanism of ferroptosis involved in PNI and manifest hypoxia as a potential therapeutic strategy for PNI recovery.

Asunto(s)

Ferroptosis , Ganglios Espinales , Subunidad alfa del Factor 1 Inducible por Hipoxia , Neuronas , Traumatismos de los Nervios Periféricos , Ratas Sprague-Dawley , Animales , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Ganglios Espinales/metabolismo , Ganglios Espinales/patología , Ferroptosis/fisiología , Neuronas/metabolismo , Neuronas/patología , Traumatismos de los Nervios Periféricos/metabolismo , Masculino , Recuperación de la Función , Especies Reactivas de Oxígeno/metabolismo , Hipoxia de la Célula , Proliferación Celular , Movimiento Celular , Ratas , Hipoxia/metabolismo , Regeneración Nerviosa/fisiología

RESUMEN

OBJECTIVE: To provide a historical perspective and narrative review on research into the molecular pathogenesis of osteoarthritis pain. DESIGN: PubMed databases were searched for combinations of "osteoarthritis", "pain" and "animal models" for papers that represented key phases in the history of osteoarthritis pain discovery research including epidemiology, pathology, imaging, preclinical modeling and clinical trials. RESULTS: The possible anatomical sources of osteoarthritis pain were identified over 50 years ago, but relatively slow progress has been made in understanding the apparent disconnect between structural changes captured by radiography and symptom severity. Translationally relevant animal models of osteoarthritis have aided in our understanding of the structural and molecular drivers of osteoarthritis pain, including molecules such as nerve growth factor and C-C motif chemokine ligand 2. Events leading to persistent osteoarthritis pain appear to involve a two-step process involving changes in joint innervation, including neo-innervation of the articular cartilage, as well as sensitization at the level of the joint, dorsal root ganglion and central nervous system. CONCLUSIONS: There remains a great need for the development of treatments to reduce osteoarthritis pain in patients. Harnessing all that we have learned over the past several decades is helping us to appreciate the important interaction between structural disease and pain, and this is likely to facilitate development of new disease modifying therapies in the future.

Asunto(s)

Cartílago Articular , Osteoartritis , Animales , Humanos , Dolor/etiología , Dolor/patología , Osteoartritis/patología , Cartílago Articular/patología , Radiografía , Ganglios Espinales/patología

RESUMEN

Despite the development of antiretroviral therapy (ART), HIV-associated distal sensory polyneuropathy remains prevalent. Using SIV-infected rhesus macaques, this study examined molecular mechanisms of peripheral and central sensitization to infer chronic pain from HIV infection. Previous studies identified atrophy in nociceptive neurons during SIV infection, which was associated with monocyte infiltration into the dorsal root ganglia (DRG). However, the sensory signaling mechanism connecting this pathology to symptoms remains unclear, especially because pain persists after resolution of high viremia and inflammation with ART. We hypothesized that residual DRG and dorsal horn neuroinflammation contributes to nociceptive sensitization. Using three cohorts of macaques [uninfected (SIV-), SIV-infected (SIV+), and SIV infected with ART (SIV+/ART)], this study showed an increase in the cellular and cytokine inflammatory profiles in the DRG of SIV+/ART macaques compared with uninfected animals. It found significant increase in the expression of nociceptive ion channels, TRPV1, and TRPA1 among DRG neurons in SIV+/ART compared with uninfected animals. SIV-infected and SIV+/ART animals showed reduced innervation of the nonpeptidergic nociceptors into the dorsal horn compared with uninfected animals. Finally, there were a significantly higher number of CD68+ cells in the dorsal horn of SIV+/ART macaques compared with uninfected animals. In summary, these data demonstrate that neuroinflammation, characteristics of nociceptor sensitization, and central terminal atrophy persists in SIV+/ART animals.

Asunto(s)

Infecciones por VIH , Síndrome de Inmunodeficiencia Adquirida del Simio , Virus de la Inmunodeficiencia de los Simios , Animales , Infecciones por VIH/patología , Síndrome de Inmunodeficiencia Adquirida del Simio/complicaciones , Síndrome de Inmunodeficiencia Adquirida del Simio/patología , Virus de la Inmunodeficiencia de los Simios/fisiología , Nociceptores/patología , Macaca mulatta , Enfermedades Neuroinflamatorias , Ganglios Espinales/patología , Atrofia/patología

RESUMEN

ABSTRACT: Neurotoxicity of chemotherapeutics involves peculiar alterations in the structure and function, including abnormal nerve signal transmission, of both the peripheral and central nervous system. The lack of effective pharmacological approaches to prevent chemotherapy-induced neurotoxicity necessitates the identification of innovative therapies. Recent evidence suggests that repeated treatment with the pentacyclic pyridoindole derivative DDD-028 can exert both pain-relieving and glial modulatory effects in mice with paclitaxel-induced neuropathy. This work is aimed at assessing whether DDD-028 is a disease-modifying agent by protecting the peripheral nervous tissues from chemotherapy-induced damage. Neuropathy was induced in animals by paclitaxel injection (2.0 mg kg -1 i.p). DDD-028 (10 mg kg -1 ) and the reference drug, pregabalin (30 mg kg -1 ), were administered per os daily starting concomitantly with the first injection of paclitaxel and continuing 10 days after the end of paclitaxel treatment. The behavioural tests confirmed the antihyperalgesic efficacy of DDD-028 on paclitaxel-induced neuropathic pain. Furthermore, the electrophysiological analysis revealed the capacity of DDD-028 to restore near-normal sensory nerve conduction in paclitaxel-treated animals. Histopathology evidence indicated that DDD-028 was able to counteract effectively paclitaxel-induced peripheral neurotoxicity by protecting against the loss of intraepidermal nerve fibers, restoring physiological levels of neurofilament in nerve tissue and plasma, and preventing morphological alterations occurring in the sciatic nerves and dorsal root ganglia. Overall, DDD-028 is more effective than pregabalin in preventing chemotherapy-induced neurotoxicity. Thus, based on its potent antihyperalgesic and neuroprotective efficacy, DDD-028 seems to be a viable prophylactic medication to limit the development of neuropathies consequent to chemotherapy.

Asunto(s)

Antineoplásicos Fitogénicos , Antineoplásicos , Neuralgia , Ratones , Animales , Neuroprotección , Pregabalina/uso terapéutico , Paclitaxel/toxicidad , Neuralgia/inducido químicamente , Neuralgia/tratamiento farmacológico , Neuralgia/patología , Nervio Ciático/patología , Antineoplásicos/toxicidad , Ganglios Espinales/patología , Antineoplásicos Fitogénicos/farmacología

RESUMEN

To guide the treatment of malignant neuropathic pain (MNP) in clinical practice, by inoculating MADB-106 breast cancer cells into the right L4 nerve root in Sprague-Dawley rats, a rat model of MNP was established, providing basic conditions for the study of neuropathic pain and development and application of therapeutic drugs. As the tumor grew over time, it pressed the nerve roots, causing nerve damage. The spinal nerve ligation (SNL) model, which is a neuropathic pain model widely used in rats, was compared with the L4 nerve root SNL model, and histologic examination of the nerve tissue of both models was performed by electron microscopy. In addition to the infiltration and erosion of the L4 nerve by tumor cells, the tumor tissue gradually grew and compressed the L4 nerve roots, resulting in hyperalgesia of the rat's posterior foot on the operative side. Some spontaneous pain phenomena were also observed, such as constant lifting or licking of the posterior foot on the operative side under quiet conditions. Electron microscopy images showed that nerve injury was due to progressive compression by the tumor, cells of which were visualized, but the injury was lighter than that in SNL rats. Imaging showed a paravertebral tumor near the L4 nerve root in the carcinomatous neuropathic pain model rat. These results suggest that progressive compression of the nerve by a malignant tumor leads to nerve damage similar to the behavioral changes associated with chronic compression injury resulting from a loose ligature of the nerve. The cancer neuropathologic pain model at the L4 nerve root was successfully established in Sprague-Dawley rats.

Asunto(s)

Neoplasias , Neuralgia , Ratas , Animales , Ratas Sprague-Dawley , Neuralgia/patología , Nervios Espinales/patología , Hiperalgesia/complicaciones , Neoplasias/complicaciones , Ganglios Espinales/patología , Ligadura/efectos adversos

RESUMEN

Despite the significant global prevalence of chronic pain, current methods to identify pain therapeutics often fail translation to the clinic. Phenotypic screening platforms rely on modeling and assessing key pathologies relevant to chronic pain, improving predictive capability. Patients with chronic pain often present with sensitization of primary sensory neurons (that extend from dorsal root ganglia [DRG]). During neuronal sensitization, painful nociceptors display lowered stimulation thresholds. To model neuronal excitability, it is necessary to maintain three key anatomical features of DRGs to have a physiologically relevant platform: (1) isolation between DRG cell bodies and neurons, (2) 3D platform to preserve cell-cell and cell-matrix interactions, and (3) presence of native non-neuronal support cells, including Schwann cells and satellite glial cells. Currently, no culture platforms maintain the three anatomical features of DRGs. Herein, we demonstrate an engineered 3D multicompartment device that isolates DRG cell bodies and neurites and maintains native support cells. We observed neurite growth into isolated compartments from the DRG using two formulations of collagen, hyaluronic acid, and laminin-based hydrogels. Further, we characterized the rheological, gelation and diffusivity properties of the two hydrogel formulations and found the mechanical properties mimic native neuronal tissue. Importantly, we successfully limited fluidic diffusion between the DRG and neurite compartment for up to 72 h, suggesting physiological relevance. Lastly, we developed a platform with the capability of phenotypic assessment of neuronal excitability using calcium imaging. Ultimately, our culture platform can screen neuronal excitability, providing a more translational and predictive system to identify novel pain therapeutics to treat chronic pain.

Asunto(s)

Dolor Crónico , Ganglios Espinales , Humanos , Ganglios Espinales/patología , Ganglios Espinales/fisiología , Dolor Crónico/patología , Neuronas , Neuritas , Hidrogeles/farmacología