MiR-15a attenuates peripheral nerve injury-induced neuropathic pain by targeting AKT3 to regulate autophagy

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.

Intradermal miR-16-5p targets Akt3 and reduces RTX-induced postherpetic neuralgia-mimic pain in mice

The molecular mechanisms of refractory pain in postherpetic neuralgia (PHN) patients are not fully understood. PHN may be related to skin abnormality after herpes zoster induced skin lesions. We previously reported 317 differentially expressed microRNAs (miRNAs) in PHN skin compared with the contralateral normal mirror skin. In this study, 19 differential miRNAs were selected and the expression was validated in other 12 PHN patients. The expression levels of miR-16-5p, miR-20a-5p, miR-505-5p, miR-3664-3p, miR-4714-3p and let-7a-5p are lower in PHN skin, which is the same as those in microarray experiment. To evaluate the effects of cutaneous miRNA on PHN, the expression of candidate miRNAs is further observed in resiniferatoxin (RTX) induced PHN-mimic mice model. In the plantar skin of RTX mice, miR-16-5p and let-7a-5p are downregulated, with the same expression trend of PHN patients. In addition, intraplantar injection of agomir-16-5p reduced mechanical hyperalgesia, and improved thermal hypoalgesia in RTX mice. Furthermore, agomir-16-5p down-regulated the expression levels of Akt3, which is the target gene of agomir-16-5p. These results suggest that intraplantar miR-16-5p may alleviate RTX induced PHN-mimic pain by inhibiting the expression of Akt3 in the skin.

Systematic identification of potential key microRNAs and circRNAs in the dorsal root ganglia of mice with sciatic nerve injury

Background

Neuropathic pain (NeP) is a pathological condition arising from a lesion or disease affecting the somatosensory system. Accumulating evidence has shown that circular RNAs (circRNAs) exert critical functions in neurodegenerative diseases by sponging microRNAs (miRNAs). However, the functions and regulatory mechanisms of circRNAs as competitive endogenous RNAs (ceRNAs) in NeP remain to be determined.

Methods

The sequencing dataset GSE96051 was obtained from the public Gene Expression Omnibus (GEO) database. First, we conducted a comparison of gene expression profiles in the L3/L4 dorsal root ganglion (DRG) of sciatic nerve transection (SNT) mice (n = 5) and uninjured mice (Control) (n = 4) to define the differentially expressed genes (DEGs). Then, critical hub genes were screened by exploring protein–protein interaction (PPI) networks with Cytoscape software, and the miRNAs bound to them were predicted and selected and then validated by qRT-PCR. Furthermore, key circRNAs were predicted and filtered, and the network of circRNA-miRNA-mRNA in NeP was constructed.

Results

A total of 421 DEGs were identified, including 332 upregulated genes and 89 downregulated genes. Ten hub genes, including IL6, Jun, Cd44, Timp1, and Csf1, were identified. Two miRNAs, mmu-miR-181a-5p and mmu-miR-223-3p, were preliminarily verified as key regulators of NeP development. In addition, circARHGAP5 and circLPHN3 were identified as key circRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that these differentially expressed mRNAs and targeting miRNAs were involved in signal transduction, positive regulation of receptor-mediated endocytosis and regulation of neuronal synaptic plasticity. These findings have useful implications for the exploration of new mechanisms and therapeutic targets for NeP.

Conclusion

These newly identified miRNAs and circRNAs in networks reveal potential diagnostic or therapeutic targets for NeP.

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.

MiR-22-3p and miR-29a-3p synergistically inhibit hepatic stellate cell activation by targeting AKT3

Hepatic fibrosis (HF) is a worldwide health problem for which there is no medically effective drug treatment at present, and which is characterized by activation of hepatic stellate cells (HSCs) and excessive extracellular matrix (ECM) deposition. The HF model in cholestatic rats by ligating the common bile duct was induced and the differentially expressed miRNAs in the liver tissues were analyzed by microarray, which showed that miR-22-3p and miR-29a-3p were significantly downregulated in bile-duct ligation (BDL) rat liver compared with the sham control. The synergistic anti-HF activity and molecular mechanism of miR-22-3p and miR-29a-3p by targeting AKT serine/threonine kinase 3 (AKT3) in HSCs were explored. The expression levels of miR-22-3p and miR-29a-3p were downregulated in activated LX-2 and human primary normal hepatic fibroblasts (NFs), whereas AKT3 was found to be upregulated in BDL rat liver and activated LX-2 cells. The proliferation, colony-forming, and migration ability of LX-2 were inhibited synergistically by miR-22-3p and miR-29a-3p. In addition, cellular senescence was induced and the expressions of the LX-2 fibrosis markers COL1A1 and α-SMA were inhibited by miR-22-3p and miR-29a-3p synergistically. Subsequently, these two miRNAs binding to the 3'UTR of AKT3 mRNA was predicted and evidenced by the luciferase reporter assay. Furthermore, the proliferation, migration, colony-forming ability, and the expression levels of COL1A1 and α-SMA were promoted and cellular senescence was inhibited by AKT3 in LX-2 cells. Thus, miR-22-3p/miR-29a-3p/AKT3 regulates the activation of HSCs, providing a new avenue in the study and treatment of HF.

Paeonol inhibits chronic constriction injury-induced astrocytic activation and neuroinflammation in rats via the HDAC/miR-15a pathway

Neuropathic pain affects millions of people in the worldwide, but the major therapeutics perform limited effectiveness. Paeonol (PAE) is widely distributed in Paeonis albiflora, and has manifested anti-inflammatory and antioxidative effects in multiple diseases. The present study aims to elucidate the effect of Paeonol (PAE) on neuropathic pain (NP) and the potential targets. Chronic constriction injury model was established to mimic NP in vivo in rats. The expression of GFAP, HDAC2, AHDAC3, Ac-H3K9, Histone-H3, Ac-H4K12, Histone-H4, TNF-α, IL-1β, and IL-6 was assessed by real-time polymerase chain reaction, western blot, and/or enzyme-linked immunosorbent assay kits. Ultimately, results indicated that intervention of PAE significantly blocked neuroinflammation and astrocytic activation via blocking HDAC/miR-15a signaling in CCI rats. These data revealed PAE is a novel therapeutic target for the treatment of neuropathic pain.

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.

Non-Coding RNAs as Novel Regulators of Neuroinflammation in Alzheimer's Disease

Alzheimer’s disease (AD) is one of the most common causes of dementia. Although significant breakthroughs have been made in understanding the progression and pathogenesis of AD, it remains a worldwide problem and a significant public health burden. Thus, more efficient diagnostic and therapeutic strategies are urgently required. The latest research studies have revealed that neuroinflammation is crucial in the pathogenesis of AD. Non-coding RNAs (ncRNAs), including long noncoding RNAs (lncRNAs), microRNAs (miRNAs), circular RNAs (circRNAs), PIWI-interacting RNAs (piRNAs), and transfer RNA-derived small RNAs (tsRNAs), have been strongly associated with AD-induced neuroinflammation. Furthermore, several ongoing pre-clinical studies are currently investigating ncRNA as disease biomarkers and therapeutic interventions to provide new perspectives for AD diagnosis and treatment. In this review, the role of different types of ncRNAs in neuroinflammation during AD are summarized in order to improve our understanding of AD etiology and aid in the translation of basic research into clinical practice.

Exploring the role of non-coding RNAs in autophagy

As a self-degradative mechanism, macroautophagy/autophagy has a role in the maintenance of energy homeostasis during critical periods in the development of cells. It also controls cellular damage through the eradication of damaged proteins and organelles. This process is accomplished by tens of ATG (autophagy-related) proteins. Recent studies have shown the involvement of non-coding RNAs in the regulation of autophagy. These transcripts mostly modulate the expression of ATG genes. Both long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been shown to modulate the autophagy mechanism. Levels of several lncRNAs and miRNAs are altered in this process. In the present review, we discuss the role of lncRNAs and miRNAs in the regulation of autophagy in diverse contexts such as cancer, deep vein thrombosis, spinal cord injury, diabetes and its complications, acute myocardial infarction, osteoarthritis, pre-eclampsia and epilepsy.Abbreviations: AMI: acute myocardial infarction; ATG: autophagy-related; lncRNA: long non-coding RNA; miRNA: microRNA.

Circular RNA Sirtuin1 represses pulmonary artery smooth muscle cell proliferation, migration and autophagy to ameliorate pulmonary hypertension via targeting microRNA-145-5p/protein kinase-B3 axis

Recently, several studies have been clarified that circular RNA (circRNA) was a vital regulatory gene of pulmonary hypertension (PH). Nevertheless, the action of circRNA in PH was not yet explored. This study was to figure out the biological function and potential molecular mechanism of circSirtuin1 (SIRT1) in PH. Construction of the PH rat model and hypoxia pulmonary artery smooth muscle cells (PASMC) model was performed, and test of circSIRT1/microRNA (miR)-145-5p/protein kinase-B3 (Akt3) was conducted. The influence of the circSIRT1/miR-145-5p/Akt3 axis on the histopathology, hemodynamics with autophagy of the pulmonary artery in rats was examined. Additionally, the impact of circSIRT1/miR-145-5p/Akt3 on the proliferation, migration and apoptosis with autophagy of PASMC under hypoxic environment was also determined. The targeting of circSIRT1/miR-145-5p/Akt3 was testified. The results manifested that circSIRT1 and Akt3 were elevated in PH, while miR-145-5p was declined. Knockdown of circSIRT1 ameliorated rat PH, suppressed PASMC proliferation, migration with autophagy in hypoxic environment. CircSIRT1 competitively combined with miR-145-5p to mediate Akt3. To sum up, circSIRT1/miR-145-5p/Akt3 was supposed to perform as a prospective molecular target for the treatment of PH.

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.

Specific microRNAs for Modulation of Autophagy in Spinal Cord Injury

The treatment of spinal cord injury (SCI) is currently a major challenge, with a severe lack of effective therapies for yielding meaningful improvements in function. Therefore, there is a great opportunity for the development of novel treatment strategies for SCI. The modulation of autophagy, a process by which a cell degrades and recycles unnecessary or harmful components (protein aggregates, organelles, etc.) to maintain cellular homeostasis and respond to a changing microenvironment, is thought to have potential for treating many neurodegenerative conditions, including SCI. The discovery of microRNAs (miRNAs), which are short ribonucleotide transcripts for targeting of specific messenger RNAs (mRNAs) for silencing, shows prevention of the translation of mRNAs to the corresponding proteins affecting various cellular processes, including autophagy. The number of known miRNAs and their targets continues to grow rapidly. This review article aims to explore the relationship between autophagy and SCI, specifically with the intent of identifying specific miRNAs that can be useful to modulate autophagy for neuroprotection and the improvement of functional recovery in SCI.

microRNA-Based Network and Pathway Analysis for Neuropathic Pain in Rodent Models

Neuropathic pain (NP) is poorly managed, and in-depth mechanisms of gene transcriptome alterations in NP pathogenesis are not yet fully understood. To determine microRNA-related molecular mechanisms of NP and their transcriptional regulation in NP, PubMed, Embase, Web of Science and CINAHL Complete (EBSCO) were searched from inception to April 2021. Commonly dysregulated miRNAs in NP were assessed. The putative targets of these miRNAs were determined using TargetScan, Funrich, Cytoscape and String database. A total of 133 literatures containing miRNA profiles studies and experimentally verify studies were included. Venn analysis, target gene prediction analysis and functional enrichment analysis indicated several miRNAs (miR-200b-3p, miR-96, miR-182, miR-183, miR-30b, miR-155 and miR-145) and their target genes involved in known relevant pathways for NP. Targets on transient receptor potential channels, voltage-gated sodium channels and voltage-gated calcium channels may be harnessed for pain relief. A further delineation of signal processing and modulation in neuronal ensembles is key to achieving therapeutic success in future studies.

Mung Bean Protein Suppresses Undernutrition-Induced Growth Deficits and Cognitive Dysfunction in Rats via Gut Microbiota-TLR4/NF-kB Pathway

Early undernutrition has been found to be closely associated with subsequent neurodevelopment. However, studies examining crude growth in terms of body weight/tail length cannot clarify how diets might mediate associations between the gut microbiota and cognitive dysfunction. In the present study, Sprague-Dawley (SD) rats were fed a 7% protein diet and mung bean protein diet (MBPD) for 6 weeks to assess central nervous system functions. Bifidobacterium longum subsp, Alloprevotella, and Lactobacillus were significantly altered after supplementary MBPD. Additionally, tryptophan, tyrosine, and glycine significantly restored in the brain, and the choline system also improved. Moreover, mung bean supplementation also upregulated expression of the brain-derived neurotrophic factor, postsynaptic density 95 protein (PSD95), synaptosome-associated protein 25 (SNAP25), downregulated toll-like receptor 4 (TLR4), and nuclear factor kB (NF-kB). Metabolites in the serum also underwent changes. Together, these results showed that malnutrition perturbed neurodevelopment, while MBPD reversed this trend.

MiR-20b-5p modulates inflammation, apoptosis and angiogenesis in severe acute pancreatitis through autophagy by targeting AKT3

BACKGROUND

Severe acute pancreatitis (SAP) is a common acute abdominal disease with high morbidity and mortality. However, the mechanism underlying SAP is still unclear.

METHODS

Cerulean and LPS (Cer-LPS) was used to establish a rat model and an in vitro model of SAP. qRT-PCR, western blot and IHC were determined to analyse the expression of mRNA and proteins. IL-1β, TNF-α and IL-6 levels were measured applying ELISA. H&E staining was determined to observe the pathological changes. Apoptosis was tested by AV-PI staining using flow cytometry. CCK8 assay was taken to detect cell viability. Cell migration was assessed by transwell assay. Tube formation assay was conducted to evaluate angiogenesis. Luciferase assay was used to detect relationship of miR-20b-5p and AKT3.

RESULTS

MiR-20b-5p was lowly expressed in SAP models both in vivo and in vitro. Overexpression of miR-20b-5p restrained inflammation and apoptosis in Cer-LPS treated pancreatic acinar cells. Furthermore, miR-20b-5p promoted the angiogenesis of vascular endothelial cells, since the viability, migration and the capability of tube formation were increased by miR-20b-5p. Mechanically, miR-20b-5p directly targeted AKT3 to promote autophagy. Furthermore, miR-20b-5p could prevent the inflammation, apoptosis and enhance angiogenesis via enhancing autophagy, which was verified in vivo.

CONCLUSION

This study demonstrated miR-20b-5p attenuates SAP through directly targeting AKT3 to regulate autophagy, subsequently inhibit inflammation and apoptosis, and promote angiogenesis. Our findings suggested a novel target of miR-20b-5p for the therapy of SAP.

Calcitonin gene-related peptide induces the histone H3 lysine 9 acetylation in astrocytes associated with neuroinflammation in rats with neuropathic pain

Aims

Calcitonin gene‐related peptide (CGRP) as a regulator of astrocyte activation may facilitate spinal nociceptive processing. Histone H3 lysine 9 acetylation (H3K9ac) is considered an important regulator of cytokine and chemokine gene expression after peripheral nerve injury. In this study, we explored the relationship between CGRP and H3K9ac in the activation of astrocytes, and elucidated the underlying mechanisms in the pathogenesis of chronic neuropathic pain.

Methods

Astroglial cells (C6) were treated with CGRP and differentially enrichments of H3K9ac on gene promoters were examined using ChIP‐seq. A chronic constriction injury (CCI) rat model was used to evaluate the role of CGRP on astrocyte activation and H3K9ac signaling in CCI‐induced neuropathic pain. Specific inhibitors were employed to delineate the involved signaling.

Results

Intrathecal injection of CGRP and CCI increased the number of astrocytes displaying H3K9ac in the spinal dorsal horn of rats. Treatment of CGRP was able to up‐regulate H3K9ac and glial fibrillary acidic protein (GFAP) expression in astroglial cells. ChIP‐seq data indicated that CGRP significantly altered H3K9ac enrichments on gene promoters in astroglial cells following CGRP treatment, including 151 gaining H3K9ac and 111 losing this mark, which mostly enriched in proliferation, autophagy, and macrophage chemotaxis processes. qRT‐PCR verified expressions of representative candidate genes (ATG12, ATG4C, CX3CR1, MMP28, MTMR14, HMOX1, RET) and RTCA verified astrocyte proliferation. Additionally, CGRP treatment increased the expression of H3K9ac, CX3CR1, and IL‐1β in the spinal dorsal horn. CGRP antagonist and HAT inhibitor attenuated mechanical and thermal hyperalgesia in CCI rats. Such analgesic effects were concurrently associated with the reduced levels of H3K9ac, CX3CR1, and IL‐1β in the spinal dorsal horn of CCI rats.

Conclusion

Our findings highly indicate that CGRP is associated with the development of neuropathic pain through astrocytes‐mediated neuroinflammatory responses via H3K9ac in spinal dorsa horn following nerve injury.

This study found that CGRP act on their astrocytic receptors and lead to H3K9 acetylation (H3K9ac), which are mainly associated with proliferation‐, autophagy‐, and inflammation‐related gene expression. The number of astrocytes with H3K9ac expression is increased after nerve injury. Inhibition of CGRP attenuates the development of neuropathic pain, which was accompanied by the suppression of H3K9ac, CX3CR1, and IL‐1β expression in CCI rats.

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

BACKGROUND

Recent studies have elucidated the instrumental role of microRNAs (miRNAs) in neuropathic pain (NP) progression. As one member of miRNAs, miR-130a-3p has been proved as a mediator in inflammation and neuronal maturation. The present study attempted to elucidate what effect miR-130a-3p exerts on NP.

MATERIALS AND METHODS

The miR-130a-3p expression in the spinal cord tissues of rat with spinal cord compression injury (SCI) and LPS-induced BV2 microglia was determined with RT-PCR, which was further applied to analyze the clinical relevance between miR-130a-3p and neuropathic pain. Besides, the expression of IGF-1, IL-1β, IL-6, and TNF-α in the spinal cord tissues of rats was measured using RT-PCR and ELISA after intrathecal injection of miR-130a-3p inhibitors and tail vein injection of IGF-1 low-expression lentivirus (Lv-shIGF-1). Further, neuronal apoptosis (labeled by Caspase3) and microglial activation (labeled by Iba1) were examined by immunohistochemistry (IHC), and the levels of IGF-1, IGF-1R, NF-κB were determined by western blot. Additionally, bioinformatic was employed to analyze the potential target genes of miR-130a-3p. Furthermore, the dual luciferase activity assay and RNA immunoprecipitation assay were conducted to further substantiate whether miR-130a-3p targets IGF-1.

RESULTS

In comparison with the sham group, the miR-130a-3p expression was remarkably up-regulated in the spinal cord lesions of SCI rats. The ELISA results showed that inhibiting the miR-130a-3p significantly reduced NP symptoms of SCI rats, mitigated neuronal apoptosis, microglial activation, repressed NF-κB phosphorylation and the IL-1β, IL-6 and TNF-α expressions in SCI rats. Contrarily, downregulation of miR-130a-3p increased IGF-1 and IGF-1R expression. What's more, we observed the same effects in BV2 microglia. In addition, the bioinformatics analysis showed that miR-130-3p targeted at the 3'-untranslated region of IGF-1 and inhibiting its expression. However, abolishing IGF-1 not only promoted the inflammatory responses in the SCI lesions, but also aggravated NP of SCI rats, while those effects were attenuated by the downregulation of miR-130a-3p.

CONCLUSION

The inhibition of miR-130a-3p expression up-regulates the IGF-1/IGF-1R signaling pathway, thus reducing neuropathic pain caused by spinal cord injury.

WITHDRAWN: MiR-216b-5p attenuates chronic constriction injury-induced neuropathic pain in female rats by targeting MAL2 and inactivating Wnt/β-catenin signaling pathway

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Upregulation of JHDM1D-AS1 alleviates neuroinflammation and neuronal injury via targeting miR-101-3p-DUSP1 in spinal cord after brachial plexus injury

BACKGROUND

Neuroinflammation in the spinal cord following acute brachial plexus injury (BPI) remains a vital cause that leads to motor dysfunction and neuropathic pain. In this study, we aim to explore the role of long non-coding RNA JHDM1D antisense 1 (JHDM1D-AS1) in mediating BPI-induced neuroinflammation and neuronal injury.

METHODS

A total brachial plexus root avulsion (tBPRA) model in adult rats and IL-1β-treated motor neuron-like NSC-34 cells and LPS-treated microglia cell line BV2 were conducted for in vivo and in vitro experiments, respectively. The expressions of JHDM1D-AS1, miR-101-3p and DUSP1, p38, NF-κB, TNF-α, IL-1β, and IL-6 were detected by RT-PCR and western blot seven days after tBPI. Immunohistochemistry (IHC) was used to detect neuronal apoptosis. CCK8 assay, Tunel assay and LDH kit were used for the detection of neuronal injury. The targeted relationships between JHDM1D-AS1 and miR-101-3p, miR-101-3p and DUSP1 were verified by RNA immunoprecipitation (RIP) and dual-luciferase reporter gene assay.

RESULTS

We found significant downregulated expression of JHDM1D-AS1 and DUSP1 but upregulated expression of miR-101-3p in the spinal cord after tBPI. Overexpression of JHDM1D-AS1 had a prominent neuroprotective effect by suppressing neuronal apoptosis and microglial inflammation through reactivation of DUSP1. Further exploration revealed that JHDM1D-AS1 may act as a competitive endogenous RNA targeting miR-101-3p, which bound on the 3'UTR of DUSP1 mRNA. In addition, overexpression of miR-101-3p could reverse the neuroprotective effects of JHDM1D-AS1 upregulation by blocking DUSP1.

CONCLUSIONS

JHDM1D-AS1 exerted neuroprotective and anti-inflammatory effects in a rat model of tBPI by regulating miR-101-3p/DUSP1 axis.

MicroRNAs in the Spinal Microglia Serve Critical Roles in Neuropathic Pain

Neuropathic pain (NP) can occur after peripheral nerve injury (PNI), and it can be converted into a maladaptive, detrimental phenotype that causes a long-term state of pain hypersensitivity. In the last decade, the discovery that dysfunctional microglia evoke pain, called "microgliopathic pain," has challenged traditional neuronal views of "pain" and has been extensively explored. Recent studies have shown that microRNAs (miRNAs) can act as activators or inhibitors of spinal microglia in NP conditions. We first briefly review spinal microglial activation in NP. We then comprehensively describe miRNA expression changes and their potential mechanisms in the response of microglia to nerve injury. We summarize the roles of the following two representative miRNAs: miR-124, which reverses NP by keeping microglia quiescent, and miR-155, which promotes NP following microglial activation. Finally, we focused on the therapeutic potential of microglial miRNAs in NP. The findings we summarized may be essential tools for basic research and clinical treatment of NP.

Role of Spinal Cord Akt-mTOR Signaling Pathways in Postoperative Hyperalgesia Induced by Plantar Incision in Mice

Poor postoperative pain (POP) control increases perioperative morbidity, prolongs hospitalization days, and causes chronic pain. However, the specific mechanism(s) underlying POP is unclear and the identification of optimal perioperative treatment remains elusive. Akt and mammalian target of rapamycin (mTOR) are expressed in the spinal cord, dorsal root ganglion, and sensory axons. In this study, we explored the role of Akt and mTOR in pain-related behaviors induced by plantar incision in mice. Plantar incision activated spinal Akt and mTOR in a dose-dependent manner. Pre-treatment with Akt inhibitors intrathecally prevented the activation of mTOR dose-dependently. In addition, blocking the Akt-mTOR signaling cascade attenuated pain-related behaviors and spinal Fos protein expression induced by plantar incision. Our observations demonstrate that Akt-mTOR might be a potential therapeutic target for the treatment of POP.

Interactions Among lncRNAs/circRNAs, miRNAs, and mRNAs in Neuropathic Pain

Neuropathic pain (NP) is directly caused by an injury or disease of the somatosensory nervous system. It is a serious type of chronic pain that is a burden to the economy and public health. Although recent studies have improved our understanding of NP, its pathogenesis has not been fully elucidated. Noncoding RNAs, including lncRNAs, circRNAs, and miRNAs, are involved in the pathological development of NP through many mechanisms. In addition, extensive evidence suggests that novel regulatory mechanisms among lncRNAs/circRNAs, miRNAs, and mRNAs play a crucial role in the pathophysiological process of NP. In this review, we comprehensively summarize the regulatory relationship among lncRNAs/circRNAs, miRNAs, and mRNAs and emphasize the important role of the lncRNA/circRNA-miRNA-mRNA axis in NP.

Non-coding RNAs in neuropathic pain

Neuro-immune alterations in the peripheral and central nervous system play a role in the pathophysiology of chronic pain in general, and members of the non-coding RNA (ncRNA) family, specifically the short, 22 nucleotide microRNAs (miRNAs) and the long non-coding RNAs (lncRNAs) act as master switches orchestrating both immune as well as neuronal processes. Several chronic disorders reveal unique ncRNA expression signatures, which recently generated big hopes for new perspectives for the development of diagnostic applications. lncRNAs may offer perspectives as candidates indicative of neuropathic pain in liquid biopsies. Numerous studies have provided novel mechanistic insight into the role of miRNAs in the molecular sequelae involved in the pathogenesis of neuropathic pain along the entire pain pathway. Specific processes within neurons, immune cells, and glia as the cellular components of the neuropathic pain triad and the communication paths between them are controlled by specific miRNAs. Therefore, nucleotide sequences mimicking or antagonizing miRNA actions can provide novel therapeutic strategies for pain treatment, provided their human homologues serve the same or similar functions. Increasing evidence also sheds light on the function of lncRNAs, which converge so far mainly on purinergic signalling pathways both in neurons and glia, and possibly even other ncRNA species that have not been explored so far.

AKT3 deficiency in M2 macrophages impairs cutaneous wound healing by disrupting tissue remodeling

AKT signaling and M2 macrophage-guided tissue repair are key factors in cutaneous wound healing. A delay in this process threatens human health worldwide. However, the role of AKT3 in delayed cutaneous wound healing is largely unknown. In this study, histological staining and transcriptomics demonstrated that prolonged tissue remodeling delayed wound healing. This delay was accompanied by defects in AKT3, collagen alpha-1(I) chain (COL1A1), and collagen alpha-1(XI) chain (COL11A1) expression and AKT signaling. The defect in AKT3 expression was M2 macrophage-specific, and decreased AKT3 protein levels were observed in CD68/CD206-positive macrophages from delayed wound tissue. Downregulation of AKT3 in M2 macrophages did not influence cell polarization but impaired collagen organization by inhibiting COL1A1 and COL11A1 expression in human skin fibroblasts (HSFs). Moreover, a co-culture model revealed that the downregulation of AKT3 in the human monocytic cell line (THP-1)-derived M2 macrophages impaired HSF proliferation and migration. Finally, cutaneous wound healing in AKT3^-/- mice was much slower than that of AKT3^+/+ mice, and F4/80 macrophages from the AKT3^-/- mice had an impaired ability to promote wound healing. Thus, the downregulation of AKT3 in M2 macrophages prolonged tissue remodeling and delayed cutaneous wound healing.