LncRNA MALAT1 promotes neuropathic pain progression through the miR‑154‑5p/AQP9 axis in CCI rat models

LncRNA 4933431K23Rik modulate microglial phenotype via inhibiting miR-10a-5p in spinal cord injury induced neuropathic pain

Neuropathic pain (NP) is caused by primary damage and dysfunction of nervous system, in which spinal cord injury (SCI) is a common cause of NP. Evidence shows that neuroinflammation and oxidative stress are related to the pathophysiology of NP, in which the activation of microglia and astrocytes in spinal is significant. Therefore, understanding the molecular mechanism of NP after SCI is of great significance. The rat model of SCI was established and BV2 cell was treated with LPS. The exosomes derived from astrocytes were extracted by centrifugation. The morphology of the exosomes was observed by electron microscope and the surface markers were detected by Western blot. LncRNA in astrocytes and astrocyte-derived exosomes were detected by qRT-PCR. The expression of microglia activation markers CD68 and Iba-1 was detected by immunohistochemistry. The von Frey test was applied to assess mechanical hypersensitivity. The heat plate analgesia instrument was used to evaluate Paw withdrawal latency (PWL). QRT-PCR used to detect expression of LncRNA49rik and miR-10a-5p. Western blot was used to detect MAPK/PI3K/AKT / mTOR signal pathway and COX2, iNOS. The content of MDA and the activity of SOD were detected by oxidative stress kit. The concentrations of IL-6, IL-1β, IL-18 and IFN-αwere detected by ELISA. The targeting relationship between LncRNA49rik and miR-10a-5p was analyzed by bioinformatics and double luciferase activity, Rip and FISH experiments. LncRNA49rik was highly expressed in astrocytes and its derived exosomes. SCI stimulated astrocytes to release exosome containing LncRNA49rik and promote microglia activation to increase inflammatory response. At the same time, overexpression of LncRNA49rik increased the incidence of NP and aggravated the level of inflammation and oxidative stress in rats with SCI. MiR-10a-5p is the target of LncRNA4933431K23Rik. Overexpression of LncRNA49rik significantly inhibited the up-regulation of miR-10a-5p. Overexpression of miR-10a-5p inhibited hyperalgesia and inflammation in SCI rats. In addition, transfection of miR-10a-5p mimics significantly inhibited the expression of MAPK/PI3K/AKT and up-regulated the expression of mTOR. Mechanism studies have shown that overexpression of miR-10a-5p weakens the phenotypic induction of microglia induced by LncRNA4933431K23Rik. LncRNA4933431K23Rik regulates microglial phenotype through inhibiting miR-10a-5p, which is responsible for NP induced by SCI.

Plasma miRNA Biomarker Signatures in Parkinsonian Syndromes

Diagnosing atypical parkinsonian syndromes (APS) remains challenging due to overlapping clinical features and limited diagnostic tools. Brain-enriched microRNAs (miRNAs), which regulate neuronal development and function, are detectable in plasma and could serve as molecular biomarkers. This prospective study aimed to identify plasma brain-enriched miRNAs that can distinguish APS and elucidate affected molecular pathways. Reverse transcription-quantitative PCR (RT-qPCR) was performed on plasma samples from patients with idiopathic Parkinson's disease (iPD), multiple system atrophy (MSA), including the cerebellar subtype (MSA-C) and the parkinsonian subtype (MSA-P), progressive supranuclear palsy (PSP), and healthy controls. MiRNA expression analysis revealed distinct molecular fingerprints for each parkinsonian syndrome, with opposite trends between MSA and iPD compared to controls, suggesting distinct pathogenic mechanisms. Most dysregulated miRNAs clustered at chromosome (Chr)14q32 and shared binding sites for CREB1, CEBPB, and MAZ transcription factors. Pathway analysis revealed enrichment in prion diseases, Hippo signaling, TGF-beta signaling, and FoxO signaling pathways.

LncRNAs Orchestrating Neuroinflammation: A Comprehensive Review

CNS diseases account for a major part of the comorbidity and mortality of the human population; moreover, neuroinflammation has become an indication for different CNS diseases, for instance, Parkinson's and Alzheimer's disease. Microglia and astrocytes are the two main glial cells that can be found in the CNS. Each of these plays an important role in mediating immune responses like inflammation. There are many studies suggesting the role of LncRNAs in mediating neuroinflammation. Indeed, LncRNAs orchestrate neuroinflammation through various mechanisms, namely miRNA sponge, and transcriptional activation/inhibition. In addition, LncRNAs regulate different downstream pathways like NF-κB, and PI3K/AKT. In this study, we gathered the existing studies regarding the mechanisms of action of LncRNAs in the pathogenesis of different CNS diseases like neurodegenerative diseases and traumatic injuries through regulating neuroinflammation. We aim to elaborate on the regulatory roles of LncRNAs in neuroinflammation and bring a more profound understanding of the etiology of CNS diseases in terms of neuroinflammation.

Downregulation of AQP9 Ameliorates NLRP3 Inflammasome-Dependent Inflammation and Pyroptosis in Crohn's Disease by Inhibiting the p38 MAPK Signaling Pathway

Crohn's disease (CD), a complex gastrointestinal disorder, can be attributed to a combination of genetic factors, immune system dysfunction, and environmental triggers. Aquaporin 9 (AQP9) has been implicated in immunoregulation and inflammation in various conditions, yet its function in CD remains unclear. Herein, we investigated the contribution of AQP9 to CD pathogenesis and its impact on inflammation and pyroptosis. Bioinformatic analysis showed a significant increase in AQP9 expression (above 2.5-fold change) in CD patients compared to controls. In vitro experiments using human colonic epithelial cells (HT-29) demonstrated that AQP9 inhibition attenuated lipopolysaccharide (LPS)-induced cell damage, inflammatory cytokine secretion, and pyroptosis. Mechanistically, AQP9 silencing suppressed NLRP3 inflammasome activation, suggesting a role in regulating pyroptosis. AQP9 silencing inhibited p38 MAPK phosphorylation, indicating a direct involvement in modulating this inflammatory pathway. Furthermore, our findings indicate that AQP9 exacerbates inflammation and pyroptosis via activating the p38 MAPK signaling pathway, known to contribute to CD pathogenesis. In vivo studies using a murine model of CD-like colitis revealed that AQP9 inhibition led to about 45% reduction in colitis severity scores and about 30% decrease in the production of inflammatory cytokine by inactivating NLRP3 inflammasome and the p38 MAPK signaling. To sum up, our study highlights the involvement of AQP9 in CD pathogenesis through modulation of inflammation and pyroptosis via the NLRP3 inflammasome and p38 MAPK signaling pathway. Targeting AQP9 may offer a promising therapeutic approach for CD by suppressing inflammatory responses and preventing tissue damage.

The role of non-coding RNAs in neuropathic pain

Neuropathic pain (NPP) is a refractory pain syndrome, caused by damage or disease of the somatosensory nervous system and characterized by spontaneous pain, hyperalgesia, abnormal pain and sensory abnormality. Non-coding RNAs (ncRNAs), including microRNA (miRNA), long non-coding RNA (lncRNA), circular RNA (circRNA) and Piwi interacting RNA (piRNA), play a notable role in initiation and maintenance of NPP. In this review, we summarize the role of ncRNAs in NPP and their underlaying mechanism. Generally, ncRNAs are interacted with mRNA, protein or DNA to regulate the molecules and signals assciated with neuroinflammation, ion channels, neurotrophic factors and others, and then involved in the occurrence and development of NPP. Therefore, this review not only contributes to deepen our understanding of the pathophysiological mechanism of NPP, but also provides theoretical basis for the development of new therapy strategies for this disorder.

Long non-coding RNA Snhg16 Lessens Ozone Curative Effect on Chronic Constriction Injury mice via microRNA-719/SCN1A axis

We investigated the function and molecular mechanism of long non-coding RNA (lncRNA) small nucleolar RNA host gene 16 (Snhg16) in modifying ozone treatment for neuropathic pain (NP) in a mouse model of chronic constriction injury (CCI). Pain-related behavioral responses were evaluated using paw withdrawal threshold (PWT), paw lifting number (PLN), and paw withdrawal latency (PWL) tests. Interleukin (IL)-1β, IL-10, IL-6, and tumor necrosis factor-alpha (TNF-α) were measured by ELISA and qRT-PCR to evaluate neuroinflammation. qRT-PCR was performed to detect expressions of Snhg16, microRNA (miR)-719, sodium voltage-gated channel alpha subunit 1 (SCN1A), and inflammatory factors. Bioinformatics, dual-luciferase reporter assay, and RNA pull-down verified the underlying molecular mechanisms. Snhg16 expression increased in CCI mice. Snhg16 overexpression retarded the curative effect of ozone and induced NP. miR-719 was sponged by Snhg16. SCN1A was a target of miR-719. Inhibition of miR-719 markedly reversed the effects of Snhg16 on pain-related behavioral responses and neuroinflammation. Upregulation of SCN1A partly abrogated the effects of elevated miR-719 levels on the occurrence of NP. The findings demonstrate that lncRNA Snhg16 promotes NP progression in CCI mice by binding to miR-719 to increase SCN1A expression. The Snhg16/miR-719/SCN1A axis may influence the curative effects of ozone therapy in treating NP.

Effect of spermidine on long non-coding RNAs MALAT1 in a rotenone induced-rat model of Parkinson's disease

BACKGROUND

Spermidine is a natural biologically active substance that has widespread influences on the body.

OBJECTIVE

This study aims to enhance our understanding of the potential effect of spermidine on long non-coding RNA MALAT1 and explore the underlying mechanism in the rotenone-induced rat model of Parkinson's disease.

METHODS

Rats were sacrificed after locomotor behavioral testing. Striatal tissues were used to assess the expression of MALAT1, oxidative stress markers, and autophagy markers.

RESULTS

Our study found that treatment with spermidine for 2 weeks during the induction of the model significantly improved behavioral assessment, dopamine levels, and attenuated the histopathological changes that occurred in PD in comparison to the non-treated group.

CONCLUSION

Our preliminary study supports the protective effect of spermidine on the activation of autophagy and its antioxidant properties. Part of the antioxidant activity is due to the inhibition of MALAT1. However, MALAT1 does not correlate with the spermidine-induced autophagy pathway.

Exploring gene signatures and regulatory networks in a rat model of sciatica: implications and validation in neuropathic pain

Background

Sciatica (neuropathic pain [NP]) is a common disease characterized by pain from radiation along the sciatic nerve. The aim of this study was to study the genes associated with chronic systolic injury of sciatic nerve (SCN-CCI) in rats by RNA-Seq technique, and to explore their potential as therapeutic targets.

Methods

Sciatic nerve rat model was obtained by ligation of sciatic nerve and divided into two groups: SCN-CCI group and Sham group. Behavioral assessments were performed to evaluate pain sensitivity, following which their spinal cord dorsal horn were resected and RNA sequencing was conducted to identify differentially expressed genes (DEGs). Bioinformatics and functional enrichment analysis was performed to identify promising DEGs and their related biological processes and pathways associated with SCN-CCI. PPI network analysis and hub gene identification were conducted. QRT-PCR, western blot, ELISA, and immunofluorescence staining were performed on rat models to validate the expression of these hub genes and investigate related proteins and inflammatory markers.

Results

The SCN-CCI rat model was successfully obtained, exhibiting increased pain sensitivity compared to the Sham group, as indicated by decreased mechanical allodynia thresholds, thermal latencies, and increased paw withdrawals. RNA-Seq analysis identified 117 DEGs in the SCN-CCI rat model, involved in various biological processes and pathways related to sciatica. PPI network analysis revealed hub genes, including Ly6g6e, which exhibited significant differential expression. QRT-PCR and Western blot analysis confirmed the expression patterns of these hub genes. Pain behavior assessment demonstrated reduced pain thresholds and increased paw flinching responses in the SCN-CCI group. Furthermore, the SCN-CCI group showed upregulated expression of Ly6g6e, increased protein levels of Ly6g6e, CGRP, and NGF, as well as elevated levels of IL-1β, MCP-1, and IL-6, and microglial cell activation in the spinal dorsal horn. ELISA results confirmed the increased levels of IL-1β, MCP-1, and IL-6 in the spinal dorsal horn.

Conclusion

These comprehensive findings provide valuable insights into the SCN-CCI rat model, DEGs associated with sciatica, hub genes (Ly6g6e as promising targets), pain behavior changes and molecular alterations.

Mechanism of IRF5-regulated CXCL13/CXCR5 Signaling Axis in CCI-induced Neuropathic Pain in Rats

BACKGROUND

Neuropathic pain is chronic and affects the patient's life. Studies have shown that IRF5 and CXCL13/CXCR5 are involved in neuropathic pain; however, their interactions are unknown.

OBJECTIVE

In this study, a rat neuropathic pain model was constructed by inducing chronic compression injury (CCI). IRF5 recombinant lentiviral vector and CXCL13 neutralizing antibody were administered to investigate their action mechanisms in neuropathic pain. Consequently, the new strategies for disease treatment could be evolved.

METHODS

The CCI rats were intrathecally injected with recombinant lentivirus plasmid LV-IRF5 (overexpression), LV-SH-IRF5 (silencing), and CXCL13 neutralizing antibody. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured. The tumor necrosis factor (TNF)-alpha, interleukin (IL)-1β, and IL-6 levels were recorded via the enzyme-linked immunosorbent assay (ELISA). The spinal cord was stained using hematoxylin-eosin (HE). The binding of IRF5 to CXCL13 was analyzed by chromatin immunoprecipitation (ChIP) and dual luciferase reporter assay. The IRF5, neuronal nuclei (NeuN), CXCL13, and CXCR5 expressions were detected through quantitative real-time polymerase chain reaction and Western blot.

RESULTS

The MWT and TWL values in the CCI group were lower than in the Sham group. The expressions of CXCL13, CXCR5, and IRF5 in CCI rats were gradually increased with the modeling time. IRF5 silencing suppressed the expression of NeuN and lumbar enlargement in CCI rats and promoted MWT and TWL. Moreover, IRF5 silencing inhibited the expressions of CXCR5 and CXCL13 genes and down-regulated the expression levels of inflammatory factors. IRF5 was directly and specifically bound with the endogenous CXCL13 promoter and thus regulated it. IRF5 overexpression exacerbated the disease phenotype of CCI-induced neuropathic pain in rats. Administration of CXCL13 neutralizing antibodies reversed the IRF5 overexpression effects.

CONCLUSION

The IRF5 silencing alleviated neuropathic pain in CCI rats by downregulating the pain threshold, inflammatory cytokine levels, and CXCL13/CXCR5 signaling. IRF5 overexpression exacerbated the disease parameters of CCI-induced neuropathic pain in rats; however, they were reversed by neutralizing antibodies against CXCL13.

Pomegranate peel extract protects against the development of diabetic cardiomyopathy in rats by inhibiting pyroptosis and downregulating LncRNA-MALAT1

Background: Pyroptosis is an inflammatory programmed cell death accompanied by activation of inflammasomes and maturation of pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18. Pyroptosis is closely linked to the development of diabetic cardiomyopathy (DC). Pomegranate peel extract (PPE) exhibits a cardioprotective effect due to its antioxidant and anti-inflammatory properties. This study aimed to investigate the underlying mechanisms of the protective effect of PPE on the myocardium in a rat model of DC and determine the underlying molecular mechanism.

Methods: Type 1 diabetes (T1DM) was induced in rats by intraperitoneal injection of streptozotocin. The rats in the treated groups received (150 mg/kg) PPE orally and daily for 8 weeks. The effects on the survival rate, lipid profile, serum cardiac troponin-1, lipid peroxidation, and tissue fibrosis were assessed. Additionally, the expression of pyroptosis-related genes (NLRP3 and caspase-1) and lncRNA-MALAT1 in the heart tissue was determined. The PPE was analyzed using UPLC-MS/MS and NMR for characterizing the phytochemical content.

Results: Prophylactic treatment with PPE significantly ameliorated cardiac hypertrophy in the diabetic rats and increased the survival rate. Moreover, prophylactic treatment with PPE in the diabetic rats significantly improved the lipid profile, decreased serum cardiac troponin-1, and decreased lipid peroxidation in the myocardial tissue. Histopathological examination of the cardiac tissues showed a marked reduction in fibrosis (decrease in collagen volume and number of TGF-β-positive cells) and preservation of normal myocardial structures in the diabetic rats treated with PPE. There was a significant decrease in the expression of pyroptosis-related genes (NLRP3 and caspase-1) and lncRNA-MALAT1 in the heart tissue of the diabetic rats treated with PPE. In addition, the concentration of IL-1β and caspase-1 significantly decreased in the heart tissue of the same group. The protective effect of PPE on diabetic cardiomyopathy could be due to the inhibition of pyroptosis and downregulation of lncRNA-MALAT1. The phytochemical analysis of the PPE indicated that the major compounds were hexahydroxydiphenic acid glucoside, caffeoylquinic acid, gluconic acid, citric acid, gallic acid, and punicalagin.

Conclusion: PPE exhibited a cardioprotective potential in diabetic rats due to its unique antioxidant, anti-inflammatory, and antifibrotic properties and its ability to improve the lipid profile. The protective effect of PPE on DC could be due to the inhibition of the NLRP3/caspase-1/IL-1β signaling pathway and downregulation of lncRNA-MALAT1. PPE could be a promising therapy to protect against the development of DC, but further clinical studies are recommended.

miR-330-3p alleviates the progression of atherosclerosis by downregulating AQP9

Atherosclerosis (AS) is the main cause of cardiovascular diseases. However, the role of AQP9 in AS is not well understood. In the present study, we predicted that miR-330-3p might regulate AQP9 in AS through bioinformatics analysis, and we established AS model using ApoE^-/- mouse (C57BL/6) with high-fat diet (HFD). Hematoxylin and eosin (H&E) and Oil red O staining were used to determine atherosclerotic lesions. CCK8 and Ethyny1-2-deoxyuridine (EdU) assays were used to investigate human umbilical vein endothelial cells (HUVECs) proliferation after treatment with 100 μg/mL ox-LDL. Wound scratch healing and transwell assays were used to measure the cell invasion and migration ability. Flow cytometry assay was used to determine apoptosis and cell cycle. A dual-luciferase reporter assay was performed to investigate the binding of miR-330-3p and AQP9. We identified that the expression of miR-330-3p in AS mice model decreased while the expression level of AQP9 increased. miR-330-3p overexpression or down-regulation of AQP9 could reduce cell apoptosis, promote cell proliferation, and migration after ox-LDL treatment. Dual-luciferase reporter assay result presented that AQP9 was directly inhibited by miR-330-3p. These results suggest that miR-330-3p inhibits AS by regulating AQP9. miR-330-3p/AQP9 axis may be a new therapeutic target for AS.

Regulation by noncoding RNAs of local translation, injury responses, and pain in the peripheral nervous system

Neuropathic pain is a chronic condition arising from damage to somatosensory pathways that results in pathological hypersensitivity. Persistent pain can be viewed as a consequence of maladaptive plasticity which, like most enduring forms of cellular plasticity, requires altered expression of specific gene programs. Control of gene expression at the level of protein synthesis is broadly utilized to directly modulate changes in activity and responsiveness in nociceptive pathways and provides an effective mechanism for compartmentalized regulation of the proteome in peripheral nerves through local translation. Levels of noncoding RNAs (ncRNAs) are commonly impacted by peripheral nerve injury leading to persistent pain. NcRNAs exert spatiotemporal regulation of local proteomes and affect signaling cascades supporting altered sensory responses that contribute to hyperalgesia. This review discusses ncRNAs found in the peripheral nervous system (PNS) that are dysregulated following nerve injury and the current understanding of their roles in pathophysiological pain-related responses including neuroimmune interactions, neuronal survival and axon regeneration, Schwann cell dedifferentiation and proliferation, intercellular communication, and the generation of ectopic action potentials in primary afferents. We review progress in the field beyond cataloging, with a focus on the relevant target transcripts and mechanisms underlying pain modulation by ncRNAs.

The emerging power and promise of non-coding RNAs in chronic pain

Chronic pain (CP) is an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage lasting longer than 3 months. CP is the main reason why people seek medical care and exerts an enormous economic burden. Genome-wide expression analysis has revealed that diverse essential genetic elements are altered in CP patients. Although many possible mechanisms of CP have been revealed, we are still unable to meet all the analgesic needs of patients. In recent years, non-coding RNAs (ncRNAs) have been shown to play essential roles in peripheral neuropathy and axon regeneration, which is associated with CP occurrence and development. Multiple key ncRNAs have been identified in animal models of CP, such as microRNA-30c-5p, ciRS-7, and lncRNA MRAK009713. This review highlights different kinds of ncRNAs in the regulation of CP, which provides a more comprehensive understanding of the pathogenesis of the disease. It mainly focuses on the contributions of miRNAs, circRNAs, and lncRNAs to CP, specifically peripheral neuropathic pain (NP), diabetic NP, central NP associated with spinal cord injury, complex regional pain syndrome, inflammatory pain, and cancer-induced pain. In addition, we summarize some potential ncRNAs as novel biomarkers for CP and its complications. With an in-depth understanding of the mechanism of CP, ncRNAs may provide novel insight into CP and could become new therapeutic targets in the future.

Long Non-Coding RNA and mRNA Profiles in the Spinal Cord of Rats with Resiniferatoxin-Induced Neuropathic Pain

Purpose

The ultrapotent transient receptor potential vanilloid 1 (TRPV1) agonist resiniferatoxin (RTX) induces small-fiber sensory neuropathy, which has been widely used model of postherpetic neuralgia to study mechanisms of neuropathic pain and new analgesics. The long non-coding RNA (lncRNA) and mRNA expression profiles in spinal dorsal horn tissues of rats six weeks after RTX injection to identify new RNAs related to neuropathic pain.

Methods

Microarray technology was applied to determine lncRNA expressions in spinal dorsal horn samples of adult rats 6 weeks after treatment with RTX or vehicle. The lncNA/mRNA co-expression network was constructed, and differential expression patterns of lncRNA and mRNA in RTX-treated rats were identified. Differential expressions of lncRNAs and mRNAs between RTX-treated samples and control samples were examined by RT-qPCR.

Results

Microarray analyses showed that 745 mRNA and 139 lncRNAs were upregulated, whereas 590 mRNA and 140 lncRNAs were downregulated in spinal dorsal horn tissues after RTX exposure. TargetScan was used to predict mRNA targets for these lncRNAs, which showed that the transcripts with multiple predicted target sites were related to neurologically important pathways. In addition, differential expressions of lncRNA (ENSRNOG00000022535, ENSRNOG00000042027, NR_027478, NR_030675) and Apobec3b mRNA in spinal cord tissue samples were validated, which confirmed the microarray data. The association between NR_030675 and Apobec3b levels was confirmed, which may be related to neuropathic pain.

Conclusion

Our study reveals lncRNA and mRNA of molecule targets that are enriched in the spinal cord dorsal horn and provides new information for further investigation on the mechanisms and therapeutics of neuropathic pain.

Acute Ethanol Challenge Differentially Regulates Expression of Growth Factors and miRNA Expression Profile of Whole Tissue of the Dorsal Hippocampus

Acute ethanol exposure produces rapid alterations in neuroimmune gene expression that are both time- and cytokine-dependent. Interestingly, adolescent rats, who often consume binge-like quantities of alcohol, displayed reduced neuroimmune responses to acute ethanol challenge. However, it is not known whether growth factors, a related group of signaling factors, respond to ethanol similarly in adults and adolescents. Therefore, Experiment 1 aimed to assess the growth factor response to ethanol in both adolescents and adults. To test this, adolescent (P29-P34) and adult (P70-P80) Sprague Dawley rats of both sexes were injected with either ethanol (3.5 g/kg) or saline, and brains were harvested 3 h post-injection for assessment of growth factor, cytokine, or miRNA expression. As expected, acute ethanol challenge significantly increased IL-6 and IκBα expression in the hippocampus and amygdala, replicating our prior findings. Acute ethanol significantly decreased BDNF and increased FGF2 regardless of age condition. PDGF was unresponsive to ethanol, but showed heightened expression among adolescent males. Because recent work has focused on the PDE4 inhibitor ibudilast for treatment in alcohol use disorder, Experiment 2 tested whether ibudilast would alter ethanol-evoked gene expression changes in cytokines and growth factors in the CNS. Ibudilast (9.0 mg/kg s.c.) administration 1 h prior to ethanol had no effect on ethanol-induced changes in cytokine or growth factor changes in the hippocampus or amygdala. To further explore molecular alterations evoked by acute ethanol challenge in the adult rat hippocampus, Experiment 3 tested whether acute ethanol would change the miRNA expression profile of the dorsal hippocampus using RNASeq, which revealed a rapid suppression of 12 miRNA species 3 h after acute ethanol challenge. Of the miRNA affected by ethanol, the majority were related to inflammation or cell survival and proliferation factors, including FGF2, MAPK, NFκB, and VEGF. Overall, these findings suggest that ethanol-induced, rapid alterations in neuroimmune gene expression were (i) muted among adolescents; (ii) independent of PDE4 signaling; and (iii) accompanied by changes in several growth factors (increased FGF2, decreased BDNF). In addition, ethanol decreased expression of multiple miRNA species, suggesting a dynamic molecular profile of changes in the hippocampus within a few short hours after acute ethanol challenge. Together, these findings may provide important insight into the molecular consequences of heavy drinking in humans.

Identifying a novel KLF2/lncRNA SNHG12/miR-494-3p/RAD23B axis in Spare Nerve Injury-induced neuropathic pain

Spinal cord injury (SCI) is a devastating condition for patients, affecting nearly 2.5 million people globally. Multiple side effects of SCI have resulted in a terrible life experience for SCI patients, of which neuropathic pain has attracted the most scientific interest. Even though many efforts have been made to attenuate or eliminate neuropathic pain induced by SCI, the outcomes for patients are still poor. Therefore, identifying novel diagnosis or therapeutic targets of SCI-induced neuropathic pain is urgently needed. Recently, multiple functions of long non-coding RNA (lncRNA) have been elucidated, including those in SCI-induced neuropathic pain. In this study, lncRNA small nucleolar RNA host gene 12 (SNHG12) was found to be upregulated in the dorsal root ganglion (DRGs) of rats with spare nerve injury (SNI). By constructing SCI rat models, we found that lncRNA SNHG12 expression was increased in the DRGs, and mainly distributed in the cytoplasm of PC12 cells. Paw withdrawal threshold (PWT), paw withdrawal latency (PWL), and enzyme linked immunosorbent assay (ELISA) results indicated that lncRNA SNHG12 knockdown attenuated SNI-induced neuropathic pain, and decreased the expression levels of interleukin (IL)−1β, IL-6, and tumour necrosis factor α (TNF-α) in the DRGs. Bioinformatics analysis, RNA pull-down, chromatin immunoprecipitation (ChIP), and luciferase reporter gene assays showed that lncRNA SNHG12 regulates the RAD23 homologue B, nucleotide excision repair protein (RAD23B) expression, through targeting micro RNA (miR)−494-3p. Furthermore, the study indicated that Kruppel-Like Factor 2 (KLF2) could regulate lncRNA SNHG12 expression in PC12 cells. This study identified a novel KLF2/lncRNA SNHG12/miR-494-3p/RAD23B axis in SNI-induced neuropathic pain, which might provide a new insight for developing novel diagnosis, or therapeutic targets of SCI-induced neuropathic pain in the future.

New Vistas in microRNA Regulatory Interactome in Neuropathic Pain

Neuropathic pain is a chronic pain condition seen in patients with diabetic neuropathy, cancer chemotherapy-induced neuropathy, idiopathic neuropathy as well as other diseases affecting the nervous system. Only a small percentage of people with neuropathic pain benefit from current medications. The complexity of the disease, poor identification/lack of diagnostic and prognostic markers limit current strategies for the management of neuropathic pain. Multiple genes and pathways involved in human diseases can be regulated by microRNA (miRNA) which are small non-coding RNA. Several miRNAs are found to be dysregulated in neuropathic pain. These miRNAs regulate expression of various genes associated with neuroinflammation and pain, thus, regulating neuropathic pain. Some of these key players include adenylate cyclase (Ac9), toll-like receptor 8 (Tlr8), suppressor of cytokine signaling 3 (Socs3), signal transducer and activator of transcription 3 (Stat3) and RAS p21 protein activator 1 (Rasa1). With advancements in high-throughput technology and better computational power available for research in present-day pharmacology, biomarker discovery has entered a very exciting phase. We dissect the architecture of miRNA biological networks encompassing both human and rodent microRNAs involved in the development of neuropathic pain. We delineate various microRNAs, and their targets, that may likely serve as potential biomarkers for diagnosis, prognosis, and therapeutic intervention in neuropathic pain. miRNAs mediate their effects in neuropathic pain by signal transduction through IRAK/TRAF6, TLR4/NF-κB, TXIP/NLRP3 inflammasome, MAP Kinase, TGFβ and TLR5 signaling pathways. Taken together, the elucidation of the landscape of signature miRNA regulatory networks in neuropathic pain will facilitate the discovery of novel miRNA/target biomarkers for more effective management of neuropathic pain.

Aquaglyceroporin Modulators as Emergent Pharmacological Molecules for Human Diseases

Aquaglyceroporins, a sub-class of aquaporins that facilitate the diffusion of water, glycerol and other small uncharged solutes across cell membranes, have been recognized for their important role in human physiology and their involvement in multiple disorders, mostly related to disturbed energy homeostasis. Aquaglyceroporins dysfunction in a variety of pathological conditions highlighted their targeting as novel therapeutic strategies, boosting the search for potent and selective modulators with pharmacological properties. The identification of selective inhibitors with potential clinical applications has been challenging, relying on accurate assays to measure membrane glycerol permeability and validate effective functional blockers. Additionally, biologicals such as hormones and natural compounds have been revealed as alternative strategies to modulate aquaglyceroporins via their gene and protein expression. This review summarizes the current knowledge of aquaglyceroporins’ involvement in several pathologies and the experimental approaches used to evaluate glycerol permeability and aquaglyceroporin modulation. In addition, we provide an update on aquaglyceroporins modulators reported to impact disease, unveiling aquaglyceroporin pharmacological targeting as a promising approach for innovative therapeutics.

LncRNA Malat-1 From MSCs-Derived Extracellular Vesicles Suppresses Inflammation and Cartilage Degradation in Osteoarthritis

Purpose: Extracellular Vesicles (EVs) derived from hMSCs, have the potential to alleviate cartilage damage and inflammation. We aimed to explore the effects of EVs derived from lncRNA malat‐1-overexpressing human mesenchymal stem cells (hMSCs) on chondrocytes.

Material and Methods: hMSCs-derived Extracellular Vesicles (hMSCs-EVs) were identified by transmission electron microscopy and western blot. We used a Sprague-Dawley (SD) rat model of CollagenaseⅡ-induced osteoarthritis (OA) as well as IL-1β-induced OA chondrocytes. Lentiviral vectors were used to overexpress lncRNA malat‐1 in hMSCs. Chondrocyte proliferation, inflammation, extracellular matrix degradation, and cell migration were measured by Edu staining, ELISA, western blot analysis, and transwell assay. Chondrocyte apoptosis was evaluated by flow cytometry, Hoechst 33342/PI Staining, and western blot. Safranine O-fast green (S-O) staining and HE staining were used to assess morphologic alterations of the rat knee joint.

Results: hMSCs^malat−1-EVs decreased MMP-13, IL-6, and Caspase-3 expression in IL-1β-induced OA chondrocytes. Moreover, hMSCs^malat−1-EVs promoted chondrocyte proliferation and migration, suppressed apoptosis, and attenuated IL-1β-induced chondrocyte injury. Our animal experiments suggested that hMSCs^malat−1-EVs were sufficient to prevent cartilage degeneration.

Conclusion: Our findings show that lncRNA malat-1from hMSCs‐delivered EVs can promote chondrocyte proliferation, alleviate chondrocyte inflammation and cartilage degeneration, and enhance chondrocyte repair. Overall, hMSCs^malat−1-EVs might be a new potential therapeutic option for patients with OA.

Differential Expression of Long Non-Coding RNAs and Their Role in Rodent Neuropathic Pain Models

Neuropathic pain, which is accompanied by an unpleasant sensation, affects the patient's quality of life severely. Considering the complexity of the neuropathic pain, there are huge unmet medical needs for it while current effective therapeutics remain far from satisfactory. Accordingly, exploration of mechanisms of neuropathic pain could provide new therapeutic insights. While numerous researches have pointed out the contribution of sensory neuron-immune cell interactions, other mechanisms of action, such as long non-coding RNAs (lncRNAs), also could contribute to the neuropathic pain observed in vivo. LncRNAs have more than 200 nucleotides and were originally considered as transcriptional byproducts. However, recent studies have suggested that lncRNAs played a significant role in gene regulation and disease pathogenesis. A substantial number of long non-coding RNAs were expressed differentially in neuropathic pain models. Besides, therapies targeting specific lncRNAs can significantly ameliorate the development of neuropathic pain, which reveals the contribution of lncRNAs in the generation and maintenance of neuropathic pain and provides a new therapeutic strategy. The primary purpose of this review is to introduce recent studies of lncRNAs on different neuropathic pain models.

Roles of Long Non-coding RNAs in the Development of Chronic Pain

Chronic pain, a severe public health issue, affects the quality of life of patients and results in a major socioeconomic burden. Only limited drug treatments for chronic pain are available, and they have insufficient efficacy. Recent studies have found that the expression of long non-coding RNAs (lncRNAs) is dysregulated in various chronic pain models, including chronic neuropathic pain, chronic inflammatory pain, and chronic cancer-related pain. Studies have also explored the effect of these dysregulated lncRNAs on the activation of microRNAs, inflammatory cytokines, and so on. These mechanisms have been widely demonstrated to play a critical role in the development of chronic pain. The findings of these studies indicate the significant roles of dysregulated lncRNAs in chronic pain in the dorsal root ganglion and spinal cord, following peripheral or central nerve lesions. This review summarizes the mechanism underlying the abnormal expression of lncRNAs in the development of chronic pain induced by peripheral nerve injury, diabetic neuropathy, inflammatory response, trigeminal neuralgia, spinal cord injury, cancer metastasis, and other conditions. Understanding the effect of lncRNAs may provide a novel insight that targeting lncRNAs could be a potential candidate for therapeutic intervention in chronic pain.

Epigenetic modifications in neuropathic pain

Neuropathic pain (NP) is a common symptom in many diseases of the somatosensory nervous system, which severely affects the patient’s quality of life. Epigenetics are heritable alterations in gene expression that do not cause permanent changes in the DNA sequence. Epigenetic modifications can affect gene expression and function and can also mediate crosstalk between genes and the environment. Increasing evidence shows that epigenetic modifications, including DNA methylation, histone modification, non-coding RNA, and RNA modification, are involved in the development and maintenance of NP. In this review, we focus on the current knowledge of epigenetic modifications in the development and maintenance of NP. Then, we illustrate different facets of epigenetic modifications that regulate gene expression and their crosstalk. Finally, we discuss the burgeoning evidence supporting the potential of emerging epigenetic therapies, which has been valuable in understanding mechanisms and offers novel and potent targets for NP therapy.

lncRNA MEG3 aggravated neuropathic pain and astrocyte overaction through mediating miR-130a-5p/CXCL12/CXCR4 axis

OBJECTIVE

Long non-coding RNAs (lncRNAs) exert a critical function in mediating neuropathic pain (NP). MEG3, a novel lncRNA, contributes to astrocyte activation and inflammation. However, its role in NP remains unclear.

METHODS

The chronic constriction injury (CCI) method was employed to construct an NP rat model. Astrocyte activation was induced by lipopolysaccharide (LPS). The profiles of MEG3, microRNA (miR)-130a-5p, CXC motif chemokine receptor 12 (CXCL12)/CXC motif chemokine receptor 4 (CXCR4), and the Rac1/NF-κB pathway in CCI rats' spinal cord tissues and astrocytes were monitored by reverse transcription-quantitative PCR (RT-qPCR) and western blot (WB). Pain scores of CCI rats were assessed. Enzyme-linked immunosorbent assay (ELISA) was adopted to monitor neuroinflammation alteration. The glial fibrillary acidic protein (GFAP)-labeled astrocytes were tested by immunohistochemistry (IHC). Bioinformatics, dual-luciferase reporter assay and RNA immunoprecipitation (RIP) were utilized to verify the molecular mechanism between MEG3 and miR-130a-3p.

RESULTS

MEG3, CXCL12 and CXCR4 were overexpressed and miR-130a-5p was knocked down in CCI rats and LPS-induced astrocytes. Up-regulating MEG3 aggravated NP, enhanced inflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor (TNF)-α, and interleukin-6 (IL-6) expression and release in CCI rats and LPS-induced astrocytes. Up-regulating miR-130-5p repressed LPS-induced inflammation in astrocytes. AS verified by the dual-luciferase reporter assay and RIP assay, MEG3 sponged miR-130a-5p as a competitive endogenous RNA (ceRNA). What's more, miR-130a-5p up-regulation weakened the MEG3-induced proinflammatory effects on LPS-induced astrocytes.

CONCLUSIONS

MEG3 aggravates NP and astrocyte activation via the miR-130a-5p/CXCL12/CXCR4 axis, which is a potential therapeutic target for NP.

Diabetic neuropathic pain induced by streptozotocin alters the expression profile of non-coding RNAs in the spinal cord of mice as determined by sequencing analysis

Diabetic neuropathic pain (DNP) is one of the most serious complications of diabetes. Patients with DNP always exhibit spontaneous and stimulus-evoked pain. However, the pathogenesis of DNP remains to be fully elucidated. Non-coding RNAs (ncRNAs) serve important roles in several cellular processes and dysregulated expression may result in the development of several diseases, including DNP. Although ncRNAs have been suggested to be involved in the pathogenesis of DNP, their precise roles remain to be determined. In the present study, sequencing analysis was used to investigate the expression patterns of coding genes, microRNAs (miRNAs), long ncRNAs (lncRNAs) and circular RNAs (circRNAs) in the spinal cord of mice with streptozotocin (STZ)-induced DNP. A total of 30 mRNAs, 148 miRNAs, 9 lncRNAs and 135 circRNAs exhibited significantly dysregulated expression 42 days after STZ injection. Functional enrichment analysis indicated that protein digestion and absorption pathways were the most significantly affected pathways of the differentially expressed (DE) mRNAs. The Rap1 signaling pathway, human T-lymphotropic virus-I infection and the MAPK signaling pathway were the three most significant pathways of the DE miRNAs. A total of 2,118 distinct circRNAs were identified and the length of the majority of the circRNAs was <1,000 nucleotides (nt) (1,552 circRNAs were >1,000 nt) with a median length of 620 nt. In the present study, the expression characteristics of coding genes, miRNAs, lncRNAs and circRNAs in DNP mice were determined; it paves the road for further studies on the mechanisms associated with DNP and potentially facilitates the discovery of novel ncRNAs for therapeutic targeting in the management of DNP.

Gene Transcript Alterations in the Spinal Cord, Anterior Cingulate Cortex, and Amygdala in Mice Following Peripheral Nerve Injury

Chronic neuropathic pain caused by nerve damage is a most common clinical symptom, often accompanied by anxiety- and depression-like symptoms. Current treatments are very limited at least in part due to incompletely understanding mechanisms underlying this disorder. Changes in gene expression in the dorsal root ganglion (DRG) have been acknowledged to implicate in neuropathic pain genesis, but how peripheral nerve injury alters the gene expression in other pain-associated regions remains elusive. The present study carried out strand-specific next-generation RNA sequencing with a higher sequencing depth and observed the changes in whole transcriptomes in the spinal cord (SC), anterior cingulate cortex (ACC), and amygdala (AMY) following unilateral fourth lumbar spinal nerve ligation (SNL). In addition to providing novel transcriptome profiles of long non-coding RNAs (lncRNAs) and mRNAs, we identified pain- and emotion-related differentially expressed genes (DEGs) and revealed that numbers of these DEGs displayed a high correlation to neuroinflammation and apoptosis. Consistently, functional analyses showed that the most significant enriched biological processes of the upregulated mRNAs were involved in the immune system process, apoptotic process, defense response, inflammation response, and sensory perception of pain across three regions. Moreover, the comparisons of pain-, anxiety-, and depression-related DEGs among three regions present a particular molecular map among the spinal cord and supraspinal structures and indicate the region-dependent and region-independent alterations of gene expression after nerve injury. Our study provides a resource for gene transcript expression patterns in three distinct pain-related regions after peripheral nerve injury. Our findings suggest that neuroinflammation and apoptosis are important pathogenic mechanisms underlying neuropathic pain and that some DEGs might be promising therapeutic targets.

The Expanding Regulatory Mechanisms and Cellular Functions of Long Non-coding RNAs (lncRNAs) in Neuroinflammation

LncRNAs have emerged as important regulatory molecules in biological processes. They serve as regulators of gene expression pathways through interactions with proteins, RNA, and DNA. LncRNA expression is altered in several diseases of the central nervous system (CNS), such as neurodegenerative disorders, stroke, trauma, and infection. More recently, it has become clear that lncRNAs contribute to regulating both pro-inflammatory and anti-inflammatory pathways in the CNS. In this review, we discuss the molecular pathways involved in the expression of lncRNAs, their role and mechanism of action during gene regulation, cellular functions, and use of lncRNAs as therapeutic targets during neuroinflammation in CNS disorders.

Identification of Slc6a19os and SOX11 as Two Novel Essential Genes in Neuropathic Pain Using Integrated Bioinformatic Analysis and Experimental Verification

The aim of this study was to identify critical genes associated with neuropathic pain. We also used the competing endogenous RNA (ceRNA) hypothesis to identify related long non-coding RNAs (lncRNAs) and messenger RNAs (miRNAs) with potential regulatory roles. We downloaded GSE107180 from the Gene Expression Omnibus database, screened differentially expressed genes (DEGs) using R software, performed comprehensive bioinformatic analyses, and validated the expression of lncRNA Slc6a19os, miR-125a-5p, miR-125b-5p, miR-351-5p, and Sox11 by qRT-PCR and Western blots. We identified 620 DEGs in spared nerve injury (SNI) mice compared with sham (control) mice, including 309 mRNAs and 311 non-coding RNAs. The up-regulated mRNAs were enriched primarily in several inflammation-related GO biological processes and KEGG signaling pathways. A ceRNA network was constructed that included 82 mRNAs, 4 miRNAs, and 2 lnRNAs. An ingenuity pathway analysis (IPA)-based interaction network for mRNAs differentially expressed in the ceRNA identified several biological processes, including "cellular development, connective tissue development and function, tissue development." Compared with sham mice, lncRNA Slc6a19os and Sox11 expression were significantly up-regulated in dorsal root ganglion (DRG) samples from SNI mice detected using qRT-PCR and Western blots (P < 0.05). MiR-125a-5p, miR-125b-5p, and miR-351-5p expression were down-regulated in DRG samples from SNI mice detected using qRT-PCR (P < 0.05). We concluded that Sox11 and lncRNA Slc6a19os were novel essential genes in the pathogenesis and progression of neuropathic pain and speculated that these two genes were regulated by miR-125a-5p, miR-125b-5p, and miR-351-5p.

Downregulation of long noncoding RNA DLEU1 attenuates hypersensitivity in chronic constriction injury-induced neuropathic pain in rats by targeting miR-133a-3p/SRPK1 axis

Background

Neuropathic pain belongs to chronic pain and is caused by the primary dysfunction of the somatosensory nervous system. Long noncoding RNAs (lncRNAs) have been reported to regulate neuronal functions and play significant roles in neuropathic pain. DLEU1 has been indicated to have close relationship with neuropathic pain. Therefore, our study focused on the significant role of DLEU1 in neuropathic pain rat models.

Methods

We first constructed a chronic constrictive injury (CCI) rat model. Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were employed to evaluate hypersensitivity in neuropathic pain. RT-qPCR was performed to analyze the expression of target genes. Enzyme-linked immunosorbent assay (ELISA) was conducted to detect the concentrations of interleukin‐6 (IL-6), tumor necrosis factor‐α (TNF-α) and IL-1β. The underlying mechanisms of DLEU1 were investigated using western blot and luciferase reporter assays.

Results

Our findings showed that DLEU1 was upregulated in CCI rats. DLEU1 knockdown reduced the concentrations of IL‐6, IL‐1β and TNF‐α in CCI rats, suggesting that neuroinflammation was inhibited by DLEU1 knockdown. Besides, knockdown of DLEU1 inhibited neuropathic pain behaviors. Moreover, it was confirmed that DLEU1 bound with miR-133a-3p and negatively regulated its expression. SRPK1 was the downstream target of miR-133a-3p. DLEU1 competitively bound with miR-133a-3p to upregulate SRPK1. Finally, rescue assays revealed that SRPK1 overexpression rescued the suppressive effects of silenced DLEU1 on hypersensitivity in neuropathic pain and inflammation of spinal cord in CCI rats.

Conclusion

DLEU1 regulated inflammation of the spinal cord and mediated hypersensitivity in neuropathic pain in CCI rats by binding with miR-133a-3p to upregulate SRPK1 expression.