Knockdown of miR-130a-3p alleviates spinal cord injury induced neuropathic pain by activating IGF-1/IGF-1R pathway

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.

Uncovering the shared neuro-immune-related regulatory mechanisms between spinal cord injury and osteoarthritis

Adults with spinal cord injury (SCI), a destructive neurological injury, have a significantly higher incidence of osteoarthritis (OA), a highly prevalent chronic joint disorder. This study aimed to dissect the neuroimmune-related regulatory mechanisms of SCI and OA using bioinformatics analysis. Using microarray data from the Gene Expression Omnibus database, differentially expressed genes (DEGs) were screened between SCI and sham samples and between OA and control samples. Common DEGs were used to construct a protein-protein interaction (PPI) network. Weighted gene co-expression network analysis (WGCNA) was used to mine SCI- and OA-related modules. Shared miRNAs were identified, and target genes were predicted using the Human MicroRNA Disease Database (HMDD) database. A miRNA-gene-pathway regulatory network was constructed with overlapping genes, miRNAs, and significantly enriched pathways. Finally, the expression of the identified genes and miRNAs was verified using RT-qPCR. In both the SCI and OA groups, 185 common DEGs were identified, and three hub clusters were obtained from the PPI network. WGCNA revealed three SCI-related modules and two OA-related modules. There were 43 overlapping genes between the PPI network clusters and the WGCNA network modules. Seventeen miRNAs shared between patients with SCI and OA were identified. A regulatory network consisting of five genes, six miRNAs, and six signaling pathways was constructed. Upregulation of CD44, TGFBR1, CCR5, and IGF1, while lower levels of miR-125b-5p, miR-130a-3p, miR-16-5p, miR-204-5p, and miR-204-3p in both SCI and OA were successfully verified using RT-qPCR. Our study suggests that a miRNA-gene-pathway network is implicated in the neuroimmune-related regulatory mechanisms of SCI and OA. CD44, TGFBR1, CCR5, and IGF1, and their related miRNAs (miR-125b-5p, miR-130a-3p, miR-16-5p, miR-204-5p, and miR-204-3p) may serve as promising biomarkers and candidate therapeutic targets for SCI and OA.

Pharmacogenetic landscape of pain management variants among Mediterranean populations

Background

Chronic pain is a major socioeconomic burden in the Mediterranean region. However, we noticed an under-representation of these populations in the pharmacogenetics of pain management studies. In this context, we aimed 1) to decipher the pharmacogenetic variant landscape among Mediterranean populations compared to worldwide populations in order to identify therapeutic biomarkers for personalized pain management and 2) to better understand the biological process of pain management through in silico investigation of pharmacogenes pathways.

Materials and Methods

We collected genes and variants implicated in pain response using the Prisma guidelines from literature and PharmGK database. Next, we extracted these genes from genotyping data of 829 individuals. Then, we determined the variant distribution among the studied populations using multivariate (MDS) and admixture analysis with R and STRUCTURE software. We conducted a Chi2 test to compare the interethnic frequencies of the identified variants. We used SNPinfo web server, miRdSNP database to identify miRNA-binding sites. In addition, we investigated the functions of the identified genes and variants using pathway enrichment analysis and annotation tools. Finally, we performed docking analysis to assess the impact of variations on drug interactions.

Results

We identified 63 variants implicated in pain management. MDS analysis revealed that Mediterranean populations are genetically similar to Mexican populations and divergent from other populations. STRUCTURE analysis showed that Mediterranean populations are mainly composed of European ancestry. We highlighted differences in the minor allele frequencies of three variants (rs633, rs4680, and rs165728) located in the COMT gene. Moreover, variant annotation revealed ten variants with potential miRNA-binding sites. Finally, protein structure and docking analysis revealed that two missense variants (rs4680 and rs6267) induced a decrease in COMT protein activity and affinity for dopamine.

Conclusion

Our findings revealed that Mediterranean populations diverge from other ethnic groups. Furthermore, we emphasize the importance of pain-related pathways and miRNAs to better implement these markers as predictors of analgesic responses in the Mediterranean region.

Mechanism of NO2-induced migraine in rats: The exploration of the role of miR-653-3p/IGF1 axis

Migraine is a severely disabling primary neurological disorder. Although some studies have confirmed that nitrogen dioxide (NO2) pollution increases the risk of migraine, and our previous study demonstrated the role of the channel protein transient receptor potential cation channel subfamily V member 1 (TRPV1) in NO2-induced migraine, the underlying mechanisms have not been fully elucidated. This study aimed to explore the intrinsic toxicity mechanism of NO2-induced migraines using transcriptome sequencing. First, the differentially expressed genes in NO2-induced migraine, insulin-like growth factor 1 (IGF1) and miRNA miR-653-3p were identified using RNA and small RNA sequencing, and a protein interaction network was constructed using STRING to explore the possible mechanisms. Next, the targeting relationship between miR-653-3p and IGF1 was determined. NO2-induced migraine was verified by silencing miR-653-3p and IGF1, independently or in combination to regulate the protein kinase B (AKT)/TRPV1 signalling pathway through the miR-653-3p/IGF1 axis. These results indicate that the key molecular mechanism of NO2-induced migraine may be that the miR-653-3p/IGF1 axis regulates the AKT/TRPV1 signalling pathway to induce migraine. The findings of this study will further elucidate the neurotoxic mechanism of NO2-induced migraines and lay a new experimental foundation for implementing migraine-related preventive and therapeutic control measures.

miR-22-3p in the rostral ventrolateral medulla promotes hypertension through inhibiting β-arrestin-1

It has been documented that increased sympathetic activity contributes to the development of cardiovascular diseases, such as hypertension. We previously reported that β-arrestin-1, a multifunctional cytoskeletal protein, was downregulated in the rostral ventrolateral medulla (RVLM) of the spontaneously hypertensive rat (SHR), and its overexpression elicited an inhibitory effect on sympathetic activity in hypertension. microRNA (miR)-22-3p has been reported to be associated with the pathological progress of hypertension. The purpose of this study was to determine the role of miR-22-3p in β-arrestin-1-mediated central cardiovascular regulation in hypertension. It was observed that miR-22-3p was upregulated in the RVLM of SHRs compared with normotensive Wistar-Kyoto (WKY) rats, and it was subsequently confirmed to target the β-arrestin-1 gene using a dual-luciferase reporter assay. miR-22-3p was downregulated in the RVLM using adeno-associated virus with 'tough decoys', which caused a significant increase of β-arrestin-1 expression and decrease of noradrenaline and blood pressure (BP) in SHRs. However, upregulation of miR-22-3p using lentivirus in the RVLM of WKY rats significantly increased BP. In in vitro PC12 cells, enhanced oxidative stress activity induced by angiotensin II was counteracted by pretreatment with miR-22-3p inhibitor, and this effect could be abolished by β-arrestin-1 gene knockdown. Furthermore, microglia exhaustion significantly diminished miR-22-3p expression, and enhanced β-arrestin-1 expression in the RVLM of SHRs. Activation of BV2 cells in vitro evoked a significant increase of miR-22-3p expression, and this BV2 cell culture medium was also able to facilitate miR-22-3p expression in PC12 cells. Collectively, our findings support a critical role for microglia-derived miR-22-3p in inhibiting β-arrestin-1 in the RVLM, which is involved in central cardiovascular regulation in hypertension. KEY POINTS: Impairment of β-arrestin-1 function in the rostral ventrolateral medulla (RVLM) has been reported to be associated with the development of sympathetic overactivity in hypertension. However, little is known about the potential mechanisms of β-arrestin-1 dysfunction in hypertension. miR-22-3p is implicated in multiple biological processes, but the role of miR-22-3p in central regulation of cardiovascular activity in hypertension remains unknown. We predicted that miR-22-3p could directly bind to the β-arrestin-1 gene (Arrb1), and this hypothesis was confirmed by using a dual-luciferase reporter assay. Inhibition of β-arrestin-1 by miR-22-3p was further verified in both in vivo and in vitro experiments. Furthermore, our results suggested miR-22-3p as a risk factor for oxidative stress in the RVLM, thus contributing to sympatho-excitation and hypertension. Our present study provides evidence that microglia-derived miR-22-3p may underlie the pathogenesis and progression of neuronal hypertension by inhibiting β-arrestin-1 in the RVLM.

Macrophage polarization in spinal cord injury repair and the possible role of microRNAs: A review

The prevention, treatment, and rehabilitation of spinal cord injury (SCI) have always posed significant medical challenges. After mechanical injury, disturbances in microcirculation, edema formation, and the generation of free radicals lead to additional damage, impeding effective repair processes and potentially exacerbating further dysfunction. In this context, inflammatory responses, especially the activation of macrophages, play a pivotal role. Different phenotypes of macrophages have distinct effects on inflammation. Activation of classical macrophage cells (M1) promotes inflammation, while activation of alternative macrophage cells (M2) inhibits inflammation. The polarization of macrophages is crucial for disease healing. A non-coding RNA, known as microRNA (miRNA), governs the polarization of macrophages, thereby reducing inflammation following SCI and facilitating functional recovery. This study elucidates the inflammatory response to SCI, focusing on the infiltration of immune cells, specifically macrophages. It examines their phenotype and provides an explanation of their polarization mechanisms. Finally, this paper introduces several well-known miRNAs that contribute to macrophage polarization following SCI, including miR-155, miR-130a, and miR-27 for M1 polarization, as well as miR-22, miR-146a, miR-21, miR-124, miR-223, miR-93, miR-132, and miR-34a for M2 polarization. The emphasis is placed on their potential therapeutic role in SCI by modulating macrophage polarization, as well as the present developments and obstacles of miRNA clinical therapy.

Circ-KATNAL1 Knockdown Reduces Neuronal Apoptosis and Alleviates Spinal Cord Injury Through the miR-98-5p/PRDM5 Regulatory Axis

Spinal cord injury (SCI) is a common disease of the central nervous system. circRNAs play a crucial role in neurological disease. The purpose of this study was to investigate the role of circ-KATNAL1 in SCI and its regulatory mechanism. T9-L10 spinal segment of Sprague Dawley rats was compressed or contused after T10 laminectomy to establish the SCI rat model. Then, rats were divided into SCI group, si-NC group, si-circ-KATNAL1 group, si-circ-KATNAL1 + antagomir NC group, si-circ-KATNAL1 + miR-98-5p antagomir group, si-circ-KATNAL1 + oe-NC group, and si-circ-KATNAL1 + oe-PRDM5 group, with 6 rats in each group. There was another sham operation group that received no treatment. Basso, Beattie, and Bresnahan (BBB) scores were used to evaluate the neural function of rats. In addition to that, the pathological changes of spinal cord tissue, neuronal apoptosis, and inflammatory responses were correspondingly observed and analyzed. Quantitative measurements of circ-KATNAL1, miR-98-5p, and PRDM5 levels were conducted, as well as analyses of their interrelationship. Circ-KATNAL1 was up-regulated in the spinal cord tissue of SCI rats, and circ-KATNAL1 knockdown could improve neural function, alleviate pathological changes of spinal cord tissue, and inhibit neuronal apoptosis and inflammatory responses in SCI rats. For miR-98-5p, circ-KATNAL1 was an upstream factor, while PRDM5 was a downstream actor. miR-98-5p deficiency or PRDM5 restoration impaired the remission effect of circ-KATNAL1 knockdown on SCI. Circ-KATNAL1 knockdown reduces neuronal apoptosis and alleviates SCI through miR-98-5p/PRDM5 regulatory axis.

Non-Coding RNAs Regulate Spinal Cord Injury-Related Neuropathic Pain via Neuroinflammation

Secondary chronic neuropathic pain (NP) in addition to sensory, motor, or autonomic dysfunction can significantly reduce quality of life after spinal cord injury (SCI). The mechanisms of SCI-related NP have been studied in clinical trials and with the use of experimental models. However, in developing new treatment strategies for SCI patients, NP poses new challenges. The inflammatory response following SCI promotes the development of NP. Previous studies suggest that reducing neuroinflammation following SCI can improve NP-related behaviors. Intensive studies of the roles of non-coding RNAs in SCI have discovered that ncRNAs bind target mRNA, act between activated glia, neuronal cells, or other immunocytes, regulate gene expression, inhibit inflammation, and influence the prognosis of NP.

LncRNA HAGLR silencing inhibits IL-1β-induced chondrocytes inflammatory injury via miR-130a-3p/JAK1 axis

BACKGROUND

Osteoarthritis (OA), the most common form of arthritis, is accompanied by destruction of articular cartilage, development of osteophyte and sclerosis of subchondral bone. This study aims to explore whether lncRNA HAGLR can play a role in OA, and further clarify the potential mechanism.

MATERIAL AND METHODS

StarBase and luciferase reporter assay were applied for predicting and confirming the interaction between lncRNA HAGLR, miR-130a-3p and JAK1. The levels of lncRNA HAGLR and miR-130a-3p were analyzed using quantitative reverse transcription PCR (qRT-PCR). The proliferation, cytotoxicity and apoptosis of CHON-001 cells were evaluated by MTT, lactate dehydrogenase assay (LDH) and Flow cytometry (FCM) analysis, respectively. Moreover, expression of cleaved Caspase3 protein were determined by Western blot assay. The release of inflammatory factors (TNF-α, IL-8, and IL-6) was detected by ELISA.

RESULTS

lncRNA HAGLR directly targets miR-130a-3p. Level of lncRNA HAGLR was substantially higher and miR-130a-3p level was memorably lower in IL-1β stimulated CHON-001 cells than that in Control group. Furthermore, lncRNA HAGLR silencing alleviated IL-1β induce chondrocyte inflammatory injury, as evidenced by increased cell viability, reduced LDH release, decreased apoptotic cells, inhibited cleaved-Caspase3 expression, and reduced secretion of secretion of inflammatory factors. However, miR-130a-3p-inhibitor reversed these findings. We also found miR-130a-3p directly targeted JAK1 and negatively regulated JAK1 expression in CHON-001 cells. In addition, JAK1-plasmid reversed the effects of miR-130a-3p mimic on IL-1β-induced chondrocytes inflammatory injury.

CONCLUSION

Silencing of lncRNA HAGLR alleviated IL-1β-stimulated CHON-001 cells injury through miR-130a-3p/JAK1 axis, revealing lncRNA HAGLR may be a valuable therapeutic target for OA therapy.

Tetramethylpyrazine and Astragaloside IV have synergistic effects against spinal cord injury-induced neuropathic pain via the OIP5-AS1/miR-34a/Sirt1/NF-κB axis

BACKGROUND

Both Tetramethylpyrazine (TMPZ) and Astragaloside IV (AGS-IV) can ameliorate neuronal apoptosis and neuroinflammation in CNS diseases. This study revolves around the underlying mechanism of TMPZ and AGS-IV in spinal cord injury (SCI)-associated neuropathic pain (NP).

MATERIALS AND METHODS

An in-vivo NP model was constructed in Sprague-Dawley (SD) rats via SCI. qRT-PCR was employed to detect OIP5-AS1 and miR-34a. The paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) of the rats were evaluated. Neuronal apoptosis in the spinal cord of rats was examined by Nissl staining and TUNEL staining. The interactions between OIP5-AS1 and miR-34a as well as miR-34a and Sirt1 were investigated through dual luciferase assay and RIP assay. The protein expressions of Bad, Bax, Caspase-3, iNOS, COX2, NF-κB, and Sirt1 were examined by western blot.

RESULTS

TMPZ and AGS-IV combination relieved behavioral symptoms of neuropathic pain in the SCI rat model, enhanced the levels of OIP5-AS1 and Sirt1, and lowered the profile of miR-34a. OIP5-AS1 downregulation weakened the neuroprotective function of TMPZ and AGS-IV in SCI rats and reversed their anti-inflammatory and anti-apoptotic effects on LPS-elicited primary spinal cord neurons. miR-34a was identified as a target of OIP5-AS1. Upregulated miR-34a partly abated the protective functions of TMPZ and AGS-IV in primary spinal cord neurons. Additionally, miR-34a targeted and repressed Sirt1, thus activating the NF-κB pathway and inflammatory reactions. Sirt1 inhibition reduced the protective effects mediated by OIP5-AS1.

CONCLUSION

TMPZ and AGS-IV ameliorate SCI-elicited NP via the OIP5-AS1/miR-34a/Sirt1/NF-κB pathway.

miRNA-130a-3p targets sphingosine-1-phosphate receptor 1 to activate the microglial and astrocytes and to promote neural injury under the high glucose condition

As a common complication of diabetes, diabetic pain neuropathy (DPN) is caused by neuron intrinsic and extrinsic factors. Neuron intrinsic factors include neuronal apoptosis and oxidative stress, while extrinsic factors are associated with glial activation. The present study was performed to reveal the functions of miR-130a-3p in apoptosis and oxidative stress of the high glucose (HG)-stimulated primary neurons as well as in the activation of microglial and astrocytes. Primary neurons, microglial, and astrocytes were isolated from newborn mice. Apoptosis was assessed by flow cytometry analysis and western blotting. Reactive oxygen species and glutathione levels were assessed to determine the oxidative stress. Markers of glial cells were detected by immunofluorescence staining. The results revealed that miR-130a-3p deficiency alleviated apoptosis and oxidative stress of HG-stimulated neurons as well as suppressed microglial and astrocyte activation. Moreover, sphingosine-1-phosphate receptor 1 (S1PR1) was found as a target downstream of miR-130a-3p. S1PR1 knockdown partially rescued the inhibitory effects of silenced miR-130a-3p on neuronal injury and glial activation. In conclusion, miR-130a-3p targets S1PR1 to activate the microglial and astrocytes and to promote apoptosis and oxidative stress of the HG-stimulated primary neurons. These findings may provide a novel insight into DPN treatment.

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.

Protective role of IGF-1 and GLP-1 signaling activation in neurological dysfunctions

Insulin-like growth factor-1 (IGF-1), a pleiotropic polypeptide, plays an essential role in CNS development and maturation. Glucagon-like peptide-1 (GLP-1) is an endogenous incretin hormone that regulates blood glucose levels and fatty acid oxidation in the brain. GLP-1 also exhibits similar functions and growth factor-like properties to IGF-1, which is likely how it exerts its neuroprotective effects. Recent preclinical and clinical evidence indicate that IGF-1 and GLP-1, apart from regulating growth and development, prevent neuronal death mediated by amyloidogenesis, cerebral glucose deprivation, neuroinflammation and apoptosis through modulation of PI3/Akt kinase, mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK/ERK). IGF-1 resistance and GLP-1 deficiency impair protective cellular signaling mechanisms, contributing to the progression of neurodegenerative diseases. Over the past decades, IGF-1 and GLP-1 have emerged as an essential component of the neuronal system and as potential therapeutic targets for several neurodegenerative and neuropsychiatric dysfunctions. There is substantial evidence that IGF-1 and GLP-1 analogues penetrate the blood-brain barrier (BBB) and exhibit neuroprotective functions, including synaptic formation, neuronal plasticity, protein synthesis, and autophagy. Conclusively, this review represents the therapeutic potential of IGF-1 and GLP-1 signaling target activators in ameliorating neurological disorders.

YY1 PROMOTES MICROGLIA M2 POLARIZATION THROUGH THE MIR-130A-3P/TREM-2 AXIS TO ALLEVIATE SEPSIS-ASSOCIATED ENCEPHALOPATHY

ABSTRACT

Purpose: Sepsis-associated encephalopathy (SAE) induces cognitive dysfunction via mechanisms that commonly involve neuroinflammation. Yin Yang 1 (YY1) is an important transcription factor that acts as a key role in sepsis and neuroepithelium development. However, the function of YY1 in SAE remains unclear. Our study aimed to probe the intrinsic and concrete molecular mechanism of YY1 in SAE. Methods: SAE cell model and SAE animal model were constructed by lipopolysaccharide (LPS) treatment and cecal ligation and puncture surgery, respectively. Behavioral tests were performed to analyze the cognitive function. The polarization state of mouse microglia (BV-2 cells) was assessed by flow cytometry assay. The mRNA and protein expressions were assessed by qRT-PCR and western blot. Finally, the binding relationships between YY1, miR-130a-3p, andTREM-2were verified by dual luciferase reporter gene assay and/or ChIP assay. Results: Here our results described that YY1 and TREM-2 were downregulated and miR-130a-3p was upregulated in SAE. YY1 overexpression could promote M2 polarization of microglia, and alleviate neuroinflammation and behavioral deficits in vitro and in vivo. YY1 could inhibit miR-130a-3p promoter activity. As expected, miR-130a-3p overexpression abolished the effects of YY1 overexpression on LPS-treated BV-2 cells. Besides, TREM-2 was identified as the target of miR-130a-3p. TREM-2 silencing could reverse the effects of miR-130a-3p inhibition on LPS-treated BV-2 cells. Conclusion: Taken together, YY1 promoted microglia M2 polarization via upregulating TREM-2 by interacting with miR-130a-3p promoter, suggesting YY1 overexpression might be a novel therapeutic strategy of SAE.

Emerging Evidence for Intrathecal Management of Neuropathic Pain Following Spinal Cord Injury

A high prevalence of patients with spinal cord injury (SCI) suffer from chronic neuropathic pain. Unfortunately, the precise pathophysiological mechanisms underlying this phenomenon have yet to be clearly elucidated and targeted treatments are largely lacking. As an unfortunate consequence, neuropathic pain in the population with SCI is refractory to standard of care treatments and represents a significant contributor to morbidity and suffering. In recent years, advances from SCI-specific animal studies and translational models have furthered our understanding of the neuronal excitability, glial dysregulation, and chronic inflammation processes that facilitate neuropathic pain. These developments have served advantageously to facilitate exploration into the use of neuromodulation as a treatment modality. The use of intrathecal drug delivery (IDD), with novel pharmacotherapies, to treat chronic neuropathic pain has gained particular attention in both pre-clinical and clinical contexts. In this evidence-based narrative review, we provide a comprehensive exploration into the emerging evidence for the pathogenesis of neuropathic pain following SCI, the evidence basis for IDD as a therapeutic strategy, and novel pharmacologics across impactful animal and clinical studies.

The etiological roles of miRNAs, lncRNAs, and circRNAs in neuropathic pain: A narrative review

Background

Non‐coding RNAs (ncRNAs) are involved in neuropathic pain development. Herein, we systematically searched for neuropathic pain‐related ncRNAs expression changes, including microRNAs (miRNAs), long non‐coding RNAs (lncRNAs), and circular non‐coding RNAs (circRNAs).

Methods

We searched two databases, PubMed and GeenMedical, for relevant studies.

Results

Peripheral nerve injury or noxious stimuli can induce extensive changes in the expression of ncRNAs. For example, higher serum miR‐132‐3p, ‐146b‐5p, and ‐384 was observed in neuropathic pain patients. Either sciatic nerve ligation, dorsal root ganglion (DRG) transaction, or ventral root transection (VRT) could upregulate miR‐21 and miR‐31 while downregulating miR‐668 and miR‐672 in the injured DRG. lncRNAs, such as early growth response 2‐antisense‐RNA (Egr2‐AS‐RNA) and Kcna2‐AS‐RNA, were upregulated in Schwann cells and inflicted DRG after nerve injury, respectively. Dysregulated circRNA homeodomain‐interacting protein kinase 3 (circHIPK3) in serum and the DRG, abnormally expressed lncRNAs X‐inactive specific transcript (XIST), nuclear enriched abundant transcript 1 (NEAT1), small nucleolar RNA host gene 1 (SNHG1), as well as ciRS‐7, zinc finger protein 609 (cirZNF609), circ_0005075, and circAnks1a in the spinal cord were suggested to participate in neuropathic pain development. Dysregulated miRNAs contribute to neuropathic pain via neuroinflammation, autophagy, abnormal ion channel expression, regulating pain‐related mediators, protein kinases, structural proteins, neurotransmission excitatory–inhibitory imbalances, or exosome miRNA‐mediated neuron–glia communication. In addition, lncRNAs and circRNAs are essential in neuropathic pain by acting as antisense RNA and miRNA sponges, epigenetically regulating pain‐related molecules expression, or modulating miRNA processing.

Conclusions

Numerous dysregulated ncRNAs have been suggested to participate in neuropathic pain development. However, there is much work to be done before ncRNA‐based analgesics can be clinically used for various reasons such as conservation among species, proper delivery, stability, and off‐target effects.

Single-cell sequencing reveals microglia induced angiogenesis by specific subsets of endothelial cells following spinal cord injury

Spinal cord injury (SCI) results in dynamic alterations of the microenvironment at the lesion site, which inevitably leads to neuronal degeneration and functional impairment. The destruction of the spinal vascular system leads to a significant deterioration of the milieu, which exacerbates inflammatory response and deprives cells of nutrient support in the lesion. Limited endogenous angiogenesis occurs after SCI, but the cellular events at the lesion site during this process are unclear so far. Here, we performed single-cell RNA sequencing (scRNA-seq) on spinal cord tissues of rats at different time points after SCI. After clustering and cell-type identification, we focused on vascular endothelial cells (ECs), which play a pivotal role in angiogenesis, and drew the cellular and molecular atlas for angiogenesis after SCI. We found that microglia and macrophages promote endogenous angiogenesis by regulating EC subsets through SPP1 and IGF signaling pathways. Our results indicate that immune cells promote angiogenesis by regulating specific subsets of vascular ECs, which provides new clues for exploring SCI intervention.

Exosomes Secreted from circZFHX3-modified Mesenchymal Stem Cells Repaired Spinal Cord Injury Through mir-16-5p/IGF-1 in Mice

BACKGROUND

Spinal cord injury (SCI) is a devastating neurological event that leads to severe motor and sensory dysfunction. Exosome-mediated transfer of circular RNAs (circRNAs) was associated with SCI, and exosomes have been reported to be produced by mesenchymal stem cells (MSCs). This study is designed to explore the mechanism of exosomal circZFHX3 on LPS-induced MSCs injury in SCI.

METHODS

Exosomes were detected by transmission electron microscope and nanoparticle tracking analysis. CD9, CD63, CD81, and TSC101, B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), Cleaved caspase 3, and Insulin-like growth factor 1 (IGF-1) protein levels were measured by western blot assay. CircZFHX3, microRNA-16-5p (miR-16-5p), and IGF-1 level were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell viability and apoptosis were detected by Cell Counting Kit-8 (CCK-8) and flow cytometry assay. Levels of IL-1β, IL-6, and TNF-α were assessed using Enzyme-linked immunosorbent assays (ELISA). ROS, LDH, and SOD levels were measured by the special kits. The binding between miR-16-5p and circZFHX3 or IGF-1 was predicted by Starbase and DianaTools and then verified by a dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. The biological role of exosomal circZFHX3 on SCI mice was examined in vivo.

RESULTS

CircZFHX3 and IGF-1 were decreased, and miR-16-5p was increased in SCI mice. Also, exosomal circZFHX3 boosted cell viability and repress apoptosis, inflammation, and oxidative stress in LPS-treated BV-2 cells in vitro. Mechanically, circZFHX3 acted as a sponge of miR-16-5p to regulate IGF-1 expression. Exosomal circZFHX3 reduced cell injury of SCI in vivo.

CONCLUSIONS

Exosomal circZFHX3 inhibited LPS-induced BV-2 cell injury partly by regulating the miR-16-5p/ IGF-1 axis, hinting at a promising therapeutic strategy for the SCI treatment.

Voluntary exercise ameliorates neuropathic pain by suppressing calcitonin gene-related peptide and ionized calcium-binding adapter molecule 1 overexpression in the lumbar dorsal horns in response to injury to the cervical spinal cord

BACKGROUND

Neuropathic pain (NP) is a frequent finding in patients diagnosed with spinal cord injuries (SCIs). To improve our understanding of the maladaptive changes taking place in the lumbar spinal cord that can lead to the development of NP and to find alternative options to treat this condition, we aimed to investigate the effects of voluntary exercise on NP after SCI and to elucidate its potential mechanisms.

METHODS

A rat model of post-SCI NP induced by compression of the posterior or lateral cervical spinal cord was used to evaluate the effects of voluntary exercise by measuring the bilateral withdrawal of the hind paws using the Von Frey filament and Hargreaves tests. The place escape/avoid paradigm was used to evaluate supraspinal pain processing and somatosensory evoked potentials (SEPs) were used to examine disturbances in proprioception. Locomotor function was evaluated using Basso, Beattie, and Bresnahan (BBB) scoring. Pathologic findings in hematoxylin and eosin-stained tissue and magnetic resonance imaging were used to evaluate the morphological changes after SCI. The lesion size within the cervical spinal cord was evaluated by staining with Eriochrome cyanine R. Quantitative polymerase chain reaction and immunohistochemistry were used to assess the expression of calcitonin gene-related peptide (CGRP) and ionized calcium-binding adapter molecule 1 (Iba-1) in the lumbar dorsal horns.

RESULTS

All injured rats developed mechanical hypersensitivity, hyposensitivity, and thermal hyperalgesia in the contralateral hind paws at 1 week post-injury. Rats that underwent lateral compression injury developed NP in the ipsilateral hind paws 1 week later than rats with a posterior compression injury. Our findings revealed that voluntary exercise ameliorated mechanical allodynia and thermal hyperalgesia, and significantly improved proprioception as measured by SEP, but had no impact on mechanical hypoalgesia or motor recovery and provided no significant neuroprotection after recovery from an acute SCI. SCI-induced NP was accompanied by increased expression of CGRP and Iba-1 in the lumbar dorsal horn. These responses were reduced in rats that underwent voluntary exercise.

CONCLUSIONS

Voluntary exercise ameliorates NP that develops in rats after compression injury. Increased expression of CGRP and Iba-1 in the lumbar dorsal horns of rats exhibiting symptoms of NP suggests that microglial activation might play a crucial role in its development. Collectively, voluntary exercise may be a promising therapeutic modality to treat NP that develops clinically in response to SCI.

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.

Advances With Non-coding RNAs in Neuropathic Pain

Neuropathic pain (NP) is one of the most common types of clinical pain. The common causes of this syndrome include injury to the central or peripheral nervous systems and pathological changes. NP is characterized by spontaneous pain, hyperalgesia, abnormal pain, and paresthesia. Because of its diverse etiology, the pathogenesis of NP has not been fully elucidated and has become one of the most challenging problems in clinical medicine. This kind of pain is extremely resistant to conventional treatment and is accompanied by serious complications. Non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), contribute to diverse biological processes by regulating the expression of various mRNAs involved in pain-related pathways, at the posttranscriptional level. Abnormal regulation of ncRNAs is closely related to the occurrence and development of NP. In this review, we summarize the current state of understanding of the roles of different ncRNAs in the development of NP. Understanding these mechanisms can help develop novel therapeutic strategies to prevent or treat chronic pain.

Emerging roles of circular RNAs in neuropathic pain

Neuropathic pain is a major type of chronic pain caused by the disease or injury of the somatosensory nervous system. It afflicts about 10% of the general population with a significant proportion of patients’ refractory to conventional medical treatment. This highlights the importance of a better understanding of the molecular pathogenesis of neuropathic pain so as to drive the development of novel mechanism‐driven therapy. Circular RNAs (circRNAs) are a type of non‐coding, regulatory RNAs that exhibit tissue‐ and disease‐specific expression. An increasing number of studies reported that circRNAs may play pivotal roles in the development of neuropathic pain. In this review, we first summarize circRNA expression profiling studies on neuropathic pain. We also highlight the molecular mechanisms of specific circRNAs (circHIPK3, circAnks1a, ciRS‐7, cZRANB1, circZNF609 and circ_0005075) that play key functional roles in the pathogenesis of neuropathic pain and discuss their potential diagnostic, prognostic, and therapeutic utilization in the clinical management of neuropathic pain.

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.

Rat Bone Mesenchymal Stem Cell-Derived Exosomes Loaded with miR-494 Promoting Neurofilament Regeneration and Behavioral Function Recovery after Spinal Cord Injury

Exosomes (Exo) exhibit numerous advantages (e.g., good encapsulation, high targeting efficiency, and easy to penetrate the blood-brain barrier to the central nervous system). Exosomes are recognized as prominent carriers of mRNAs, siRNAs, miRNAs, proteins, and other bioactive molecules. As confirmed by existing studies, miR-494 is important to regulate the occurrence, progression, and repair of spinal cord injury (SCI). We constructed miR-494-modified exosomes (Exo-miR-494). As indicated from related research in vitro and vivo, Exo-miR-494 is capable of effectively inhibiting the inflammatory response and neuronal apoptosis in the injured area, as well as upregulating various anti-inflammatory factors and miR-494 to protect neurons. Moreover, it can promote the regeneration of the neurofilament and improve the recovery of behavioral function of SCI rats.

MiRNA-130a promotes inflammation to accelerate atherosclerosis via the regulation of proliferator-activated receptor γ (PPARγ) expression

OBJECTIVE

In this study, we aimed to evaluate the possible function of miR-130a in atherosclerosis (AS), protection against AS, and its molecular biological mechanism.

METHODS

Apoe-/- mice were fed a high-fat diet as the AS mice model. Human umbilical vein endothelial cells (HUVECs) were used as in vitro model. Serum samples or cells were used to measure the expression of inflammation. Serum samples or cells were used to determine MiRNA expression profiles using the edgeR tool from Bioconductor. Western Blot analysis was used to assess protein expressions of proliferator-activated receptor γ (PPARγ) and nuclear factor (NF)-κB.

RESULTS

MiRNA-130a expression was up-regulated in atherosclerotic mice. In addition, over-expression of miRNA-130a promoted inflammation factors [tumor necrosis factor (TNF)-α and interleukin (IL)-1β, IL-6, and IL-8] in the in vitro model of AS. However, down-regulation of miRNA-130a reduced inflammation (suppressed TNF-α, IL-1β, IL-6 and IL-8) in the in vitro model. Furthermore, over-expression of miRNA-130a could also suppress the protein expression of PPARγ and induce NF-κB protein expression in the in vitro model. However, suppression of miRNA-130a induced the protein expression of PPARγ and suppressed NF-κB protein expression in the in vitro model of AS. Activation of PPARγ reduced the pro-inflammatory effects of miRNA-130a on the AS-induced in vitro model.

CONCLUSION

These results strongly support that miRNA-130a suppression can protect against atherosclerosis through inhibiting inflammation by regulating the PPARγ/ NF-κB expression.

Chemotherapy-induced peripheral neuropathy is promoted by enhanced spinal insulin-like growth factor-1 levels via astrocyte-dependent mechanisms

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and intractable complication in chemotherapy-receiving patients. Insulin-like growth factor-1 (IGF-1) is a popular neurotrophin with various functions, such as maintaining neuronal survival and synaptic functioning in the central nervous system. Therefore, we hypothesized that the IGF-1 signaling pathway could be a candidate target for treating CIPN.

METHODS

We established the CIPN model by injecting mice intraperitoneally with oxaliplatin and assessed IGF-1 protein expression, its receptor IGF1R, phospho-IGF1R (p-IGF1R), interleukin-17A (IL-17A), tumor necrosis factor-α (TNF-α), and calcitonin gene-related peptide (CGRP) in the lumbar spinal cord with Western blot and immunofluorescence. To examine the effect of IGF-1 signaling on CIPN, we injected mice intrathecally or intraperitoneally with mouse recombinant IGF-1 (rIGF-1).

RESULTS

IGF-1 protein expression decreased significantly in the spinal cord on D3 and D10 (the 3rd and 10th days after beginning oxaliplatin chemotherapy) and was co-localized with astrocytes primarily in the lumbar spinal cord, whereas IGF1R was predominantly expressed on neurons. Both intrathecally- and intraperitoneally-administered rIGF-1 relieved the chemotherapy-induced pain-like behavior and reduced IL-17A, TNF-α, and CGRP protein expressions in the spinal cord.

CONCLUSION

Our results indicate a vital role for IGF-1 signaling in CIPN. Targeting IGF-1 signaling could be a potent therapeutic strategy for treating CIPN in clinical settings.

Chicoric acid alleviates LPS-induced inflammatory response through miR-130a-3p/IGF-1pathway in human lung A549 epithelial cells

To investigate the effects and potential mechanisms of chicoric acid (CA) on LPS-induced inflammatory response in A549 cells. 0–800 μM CA was added to A549 cells to determine the toxicity of CA using MTT assay. Then, 2 μg/mL LPS and 50 μM CA were simultaneously added to A549 cells to investigate the effects of CA. In order to investigate the effects of miR-130a-3p and IGF-1 on LPS-induced A549 cells, cells were infected with inhibitor of miR-130a-3p and si RNA IGF-1. The levels of inflammatory cytokines such as IL-1β, IL-6, and TNF-α were measured by real-time RT-PCR and enzyme-linked immunosorbent (ELISA) assay. The IGF-1 pathway and NF-κB expression were measured using immunoblot assay. Moreover, a luciferase activity assay was used to indicate the binding site of miR-130a-3p on the 3′UTR of IGF-1. 0–50 μM CA had no toxicity on A549 cells. Thus, we chose 50 μM CA for the following study. CA attenuated the inflammatory response by LPS through decreasing IL-1β, IL-6, and TNF-α levels and increasing IGF-1/IGF-1R expression. Inhibition of miR-130a-3p reduced the inflammatory response and restored IGF-1/IGF-1R pathway induced by LPS. Furthermore, luciferase activity results indicated that miR-130a-3p directly targeted IGF-1 to regulate inflammatory response. CA alleviates LPS-induced inflammatory response through miR-130a-3p/IGF-1pathway in A549 cells.