Downregulating lncRNA PVT1 Relieves Astrocyte Overactivation Induced Neuropathic Pain Through Targeting miR-186-5p/CXCL13/CXCR5 Axis

Alteration in the expression of long non-coding RNAs in the circulation of migraineurs

BACKGROUND

Current studies have shown emerging roles of lncRNAs in the pathobiology of neuropathic pain and migraine.

METHODS

We have chosen five lncRNAs, namely, PVT1, DSCAM-AS, MEG3, LINC-ROR, and SPRY4-IT1 for assessment of their expression in the circulation of migraineurs.

RESULTS

Expressions of PVT1 and MEG3 were higher in total migraineurs and both subgroups compared with controls (P < 0.0001). Meanwhile, expression of both lncRNA was higher in migraineurs with aura versus migraineurs without aura (P value < 0.0001 and = 0.01, respectively). Expression of DSCAM-AS1 was not different between any groups of patients compared with controls. Expression of LINC-ROR was elevated in total patients and patients with aura compared with controls (P value = 0.0002 and < 0.0001, respectively). It was also over-expressed in migraineurs with aura vs. migraineurs without aura (P = 0.01). Finally, expression of SPRY4-IT1 was higher in total patients and patients without aura compared with migraine-free persons (P values < 0.0001). Expressions of five mentioned lncRNAs were correlated in almost all study groups. In patients without aura, correlations were significant only for two pairs (SPRY4-IT1/PVT1 and SPRY4-IT1/DSCAM-AS1). PVT1 and MEG3 had the appropriate AUC, sensitivity and specificity values for separation of total migraineurs and both groups of patients from controls. The highest AUC value was reported for PVT1 in separation of migraineurs with aura from healthy controls (AUC = 0.98).

CONCLUSION

Cumulatively, our study shows evidence for deregulation of lncRNAs in migraineurs.

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.

LncRNA-PCat19 acts as a ceRNA of miR-378a-3p to facilitate microglia activation and accelerate chronic neuropathic pain in rats by promoting KDM3A-mediated BDNF demethylation

The pathogenesis of neuropathic pain (NP) is complex, and there are various pathological processes. Previous studies have suggested that lncRNA PCAT19 is abnormally expressed in NP conduction and affects the occurrence and development of pain. The aim of this study is to analyze the role and mechanism of PCAT19 in NP induced by chronic compressive nerve injury (CCI) in mice. In this study, C57BL/6 mice were applied to establish the CCI model. sh-PCAT19 was intrathecally injected once a day for 5 consecutive days from the second day after surgery. We discovered that PCat19 level was gradually up-regulated with the passage of modeling time. Downregulation of Iba-1-positive expression, M1/M2 ratio of microglia, and pro-inflammatory factors in the spinal cords of CCI-mice after PCat19 knock-downed was observed. Mechanically, the expression of miR-378a-3p was negatively correlated with KDM3A and PCat19. Deletion of KDM3A prevented H3K9me2 demethylation of BDNF promoter and suppressed BDNF expression. Further, KDM3A promotes CCI-induced neuroinflammation and microglia activation by mediating Brain-derived neurotrophic factor (BDNF) demethylation. Together, the results suggest that PCat19 may be involved in the development of NP and that PCat19 shRNA injection can attenuate microglia-induced neuroinflammation by blocking KDM3A-mediated demethylation of BDNF and BDNF release.

Circulating microRNA Profiles Identify a Patient Subgroup with High Inflammation and Severe Symptoms in Schizophrenia Experiencing Acute Psychosis

Schizophrenia is a complex and heterogenous psychiatric disorder. This study aimed to demonstrate the potential of circulating microRNAs (miRNAs) as a clinical biomarker to stratify schizophrenia patients and to enhance understandings of their heterogenous pathophysiology. We measured levels of 179 miRNA and 378 proteins in plasma samples of schizophrenia patients experiencing acute psychosis and obtained their Positive and Negative Syndrome Scale (PANSS) scores. The plasma miRNA profile revealed three subgroups of schizophrenia patients, where one subgroup tended to have higher scores of all the PANSS subscales compared to the other subgroups. The subgroup with high PANSS scores had four distinctively downregulated miRNAs, which enriched 'Immune Response' according to miRNA set enrichment analysis and were reported to negatively regulate IL-1β, IL-6, and TNFα. The same subgroup had 22 distinctively upregulated proteins, which enriched 'Cytokine-cytokine receptor interaction' according to protein set enrichment analysis, and all the mapped proteins were pro-inflammatory cytokines. Hence, the subgroup is inferred to have comparatively high inflammation within schizophrenia. In conclusion, miRNAs are a potential biomarker that reflects both disease symptoms and molecular pathophysiology, and identify a patient subgroup with high inflammation. These findings provide insights for the precision medicinal strategies for anti-inflammatory treatments in the high-inflammation subgroup of schizophrenia.

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.

LncRNA UCA1 could regulate the progression of neuropathic pain by regulating miR-135a-5p

BACKGROUND

Neuropathic pain (NPP) is known as a common neurological disease with high incidence rate. The present work focused on the roles of long non-coding RNA urothelial carcinoma antigen 1(LncRNA UCA1) in NPP and the possible underlying mechanism.

METHODS

NPP rat model has been established and the levels of UCA1 NPP as well as the group has been determined by RT-PCR method. Next, NPP rats were treated by UCA1 over-expression plasmid and the behaviors, as well as expression of inflammatory cytokines have been examined. Furthermore, target miRNA of UCA1, miR-135a-5p, has been predicted by bioinformatic method, and further verified with the dual-luciferase reporter assay. Finally, the effects of UCA1/ miR-135a-5p axis have been further evaluated.

RESULTS

Expressions of UCA1 were markedly decreased and miR-135a-5p were significantly increased in NPP rats in comparison with the control rats. Over-expression of UCA1 alleviated the inflammatory condition in NPP model by decreasing expression of inflammatory cytokines. miR-135a-5p was confirmed to be a target microRNA of UCA1, and UCA1 may regulate the progress of NPP via targeting miR-135a-5p.

CONCLUSION

UCA1 could regulate NPP via affecting miR-135a-5p expression.

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.

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.

MiR-30b-5p attenuates the inflammatory response and facilitates the functional recovery of spinal cord injury by targeting the NEFL/mTOR pathway

BACKGROUND

Neurofilament light chain (NEFL) has been identified as a biomarker for spinal cord injury (SCI), but its effect and underlying mechanism in SCI remain unclear.

METHODS

SCI rat models were established for in vivo studies. Lipopolysaccharide (LPS)-induced cell models were used for in vitro studies. The protein and mRNA expression levels of genes were evaluated by western blotting and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The pathological changes in rats after SCI were subjected to histological examinations. The interaction of NEFL and upstream miRNAs was explored using dual-luciferase reporter gene assays.

RESULTS

NEFL was highly expressed in SCI rat spinal cord tissues and LPS-stimulated PC12 cells. NEFL silencing showed an inhibitory effect on the morphological changes of SCI rats and the secretion of inflammatory factors and facilitated functional recovery of SCI rats. MiR-30b-5p was demonstrated to target NEFL and negatively regulate NEFL mRNA and protein levels. Downregulation of miR-30b-5p in SCI cell and rat models was demonstrated. MiR-30b-5p alleviated the inflammatory response in SCI rat models and LPS-stimulated PC12 cells and promoted functional recovery in rats by targeting NEFL. NEFL activated mTOR signaling. MiR-30b-5p inactivated mTOR signaling by negatively regulating NEFL.

CONCLUSION

MiR-30b-5p alleviated the inflammatory response and facilitated the functional recovery of SCI rats by targeting NEFL to inactivate the mTOR pathway.

Hydrogen-Rich Saline Attenuates Chronic Allodynia after Bone Fractures via Reducing Spinal CXCL1/CXCR2-Mediated Iron Accumulation in Mice

PURPOSE

Neuroinflammation often initiates iron overload in the pathogenesis of neurological disorders. Chemokine-driven neuroinflammation is required for central sensitization and chronic allodynia following fractures, but specific molecular modulations are elusive. This present study explored whether hydrogen-rich saline, as one potent anti-inflammatory pharmaceutical, could alleviate fracture-caused allodynia by suppressing chemokine CXCL1 expression and iron overload.

METHODS

A mouse model of tibial fracture with intramedullary pinning was employed for establishing chronic allodynia. Three applications of hydrogen-rich saline (1, 5 or 10 mL/kg) were administrated intraperitoneally on a daily basis from days 4 to 6 following fractures. Spinal CXCL1 and its receptor CXCR2 levels, transferrin receptor 1 (TfR1) expression and iron concentration were examined. Recombinant CXCL1, a selective CXCR2 antagonist and an iron chelator were used for verification of mechanisms.

RESULTS

Repetitive injections of hydrogen-rich saline (5 and 10 mL/kg but not 1 mL/kg) prevent fracture-caused mechanical allodynia and cold allodynia in a dose-dependent manner. Single exposure to hydrogen-rich saline (10 mL/kg) on day 14 after orthopedic surgeries controls the established persistent fracture allodynia. Furthermore, hydrogen-rich saline therapy reduces spinal CXCL1/CXCR2 over-expression and TfR1-mediated iron accumulation in fracture mice. Spinal CXCR2 antagonism impairs allodynia and iron overload following fracture surgery. Intrathecal delivery of recombinant CXCL1 induces acute allodynia and spinal iron overload, which is reversed by hydrogen-rich saline. Moreover, iron chelation alleviates exogenous CXCL1-induced acute pain behaviors.

CONCLUSIONS

These findings identify that hydrogen-rich saline confers protection against fracture-caused chronic allodynia via spinal down-modulation of CXCL1-dependent TfR1-mediated iron accumulation in mice.

Non-coding RNA and n6-methyladenosine modification play crucial roles in neuropathic pain

After peripheral nerve injury, pain signals are transmitted from primary sensory neurons in the dorsal root ganglion (DRG) to the central nervous system. Epigenetic modification affects neuropathic pain through alterations in the gene expression in pain-related areas and glial cell activation. Recent studies have shown that non-coding RNA and n6-methyladenosine (m6A) methylation modification play pivotal regulatory roles in the occurrence and maintenance of neuropathic pain. Dysregulation of the RNA m6A level via dynamic changes in methyltransferase and demethylase after central or peripheral nerve injury commonly regulates pain-associated genes, contributing to the induction and maintenance of neuropathic pain. The dynamic process has significant implications for the development and maintenance of neuropathic pain. However, the underlying mechanisms by which non-coding RNA and m6A RNA modification regulate neuropathic pain are not well-characterized. This article elucidates the multiple mechanisms of non-coding RNA and m6A methylation in the context of neuropathic pain, and summarizes its potential functions as well as recent advances.

Astrocytes in Chronic Pain: Cellular and Molecular Mechanisms

Chronic pain is challenging to treat due to the limited therapeutic options and adverse side-effects of therapies. Astrocytes are the most abundant glial cells in the central nervous system and play important roles in different pathological conditions, including chronic pain. Astrocytes regulate nociceptive synaptic transmission and network function via neuron–glia and glia–glia interactions to exaggerate pain signals under chronic pain conditions. It is also becoming clear that astrocytes play active roles in brain regions important for the emotional and memory-related aspects of chronic pain. Therefore, this review presents our current understanding of the roles of astrocytes in chronic pain, how they regulate nociceptive responses, and their cellular and molecular mechanisms of action.

Promising Advances in Pharmacotherapy for Patients with Spinal Cord Injury-A Review of Studies Performed In Vivo with Modern Drugs

Spinal cord injury (SCI) is a pathological neurological condition that leads to significant motor dysfunction. It is a condition that occurs as a result of tragic accidents, violent acts, or as a consequence of chronic diseases or degenerative changes. The current treatments for patients with SCI have moderate efficacy. They improve the quality of life of patients, but they are still doomed to long-term disability. In response to the modern directions of research on possible therapeutic methods that allow for the recovery of patients with SCI, a scientific review publication is needed to summarize the recent developments in this topic. The following review is focused on the available pharmacological treatments for SCIs and the problems that patients face depending on the location of the injury. In the following review, the research team describes problems related to spasticity and neuropathic pain; possible therapeutic pathways are also described for neuroprotection and the improvement of neurotransmission within the injured spinal cord, and the review focuses on issues related to oxidative stress.

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.

RNA sequencing profiling of mRNAs, long noncoding RNAs, and circular RNAs in Trigeminal Ganglion following Temporomandibular Joint inflammation

Patients with temporomandibular joint disorders (TMD) have high levels of inflammatory pain-related disability, which seriously affects their physical and mental health. However, an effective treatment is yet to be developed. Both circular RNAs (circRNAs) and long noncoding RNAs (lncRNAs) contribute to regulating pain conduction. In our current study, we report the expression profiles of circRNAs, lncRNAs, and mRNAs in the trigeminal ganglion (TG) associated with complete Freund’s adjuvant (CFA)-induced TMD inflammation pain. The collected TGs from the experimental (CFA) and control (saline) groups were processed for deep RNA sequencing. Overall, 1078,909,068 clean reads were obtained. A total of 15,657 novel lncRNAs were identified, where 281 lncRNAs were differentially expressed on CFA3D and 350 lncRNAs were differentially expressed on CFA6D. In addition, a total of 55,441 mRNAs and 27,805 circRNAs were identified, where 3,914 mRNAs and 91 circRNAs were found differentially expressed, between the CFA3D and saline groups, while 4,232 mRNAs and 98 DE circRNAs were differentially expressed between the CFA6D and saline groups. Based on functional analyses, we found that the most significant enriched biological processes of the upregulated mRNAs were involved in the immunity, neuron projection, inflammatory response, MAPK signaling pathway, Ras signaling pathway, chemokine signaling pathway, and inflammatory response in TG. Further analyses of Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes pathway suggest the involvement of dysregulated genes in the pain occurrence mechanism. Our findings provide a resource for expression patterns of gene transcripts in regions related to pain. These results suggest that apoptosis and neuroinflammation are important pathogenic mechanisms underlying TMD pain. Some of the reported differentially expressed genes might be considered promising therapeutic targets. The current research study revealed the expression profiles of circRNAs, lncRNAs, and mRNAs during TMD inflammation pain and sheds light on the roles of circRNAs and lncRNAs underlying the pain pathway in the trigeminal system of TMD inflammation pain.

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.

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.

Reactive Astrocytes in Central Nervous System Injury: Subgroup and Potential Therapy

Traumatic central nervous system (CNS) injury, which includes both traumatic brain injury (TBI) and spinal cord injury (SCI), is associated with irreversible loss of neurological function and high medical care costs. Currently, no effective treatment exists to improve the prognosis of patients. Astrocytes comprise the largest population of glial cells in the CNS and, with the advancements in the field of neurology, are increasingly recognized as having key functions in both the brain and the spinal cord. When stimulated by disease or injury, astrocytes become activated and undergo a series of changes, including alterations in gene expression, hypertrophy, the loss of inherent functions, and the acquisition of new ones. Studies have shown that astrocytes are highly heterogeneous with respect to their gene expression profiles, and this heterogeneity accounts for their observed context-dependent phenotypic diversity. In the inured CNS, activated astrocytes play a dual role both as regulators of neuroinflammation and in scar formation. Identifying the subpopulations of reactive astrocytes that exert beneficial or harmful effects will aid in deciphering the pathological mechanisms underlying CNS injuries and ultimately provide a theoretical basis for the development of effective strategies for the treatment of associated conditions. Following CNS injury, as the disease progresses, astrocyte phenotypes undergo continuous changes. Although current research methods do not allow a comprehensive and accurate classification of astrocyte subpopulations in complex pathological contexts, they can nonetheless aid in understanding the roles of astrocytes in disease. In this review, after a brief introduction to the pathology of CNS injury, we summarize current knowledge regarding astrocyte activation following CNS injury, including: (a) the regulatory factors involved in this process; (b) the functions of different astrocyte subgroups based on the existing classification of astrocytes; and (c) attempts at astrocyte-targeted therapy.

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.

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.