MicroRNA-21-5p mediates TGF-β-regulated fibrogenic activation of spinal fibroblasts and the formation of fibrotic scars after spinal cord injury

Celastrol inhibits oligodendrocyte and neuron ferroptosis to promote spinal cord injury recovery

BACKGROUND

Spinal cord injury (SCI) is a traumatic injury to the central nervous system and can cause lipid peroxidation in the spinal cord. Ferroptosis, an iron-dependent programmed cell death, plays a key role in the pathophysiology progression of SCI. Celastrol, a widely used antioxidant drug, has potential therapeutic value for nervous system.

PURPOSE

To investigate whether celastrol can be a reliable candidate for ferroptosis inhibitor and the molecular mechanism of celastrol in repairing SCI by inhibiting ferroptosis.

METHODS

First, a rat SCI model was constructed, and the recovery of motor function was observed after treatment with celastrol. The regulatory effect of celastrol on ferroptosis pathway Nrf2-xCT-GPX4 was detected by Western blot and immunofluorescence. Finally, the ferroptosis model of neurons and oligodendrocytes was constructed in vitro to further verify the mechanism of inhibiting ferroptosis by celastrol.

RESULTS

Our results demonstrated that celastrol promoted the recovery of spinal cord tissue and motor function in SCI rats. Further in vitro and in vivo studies showed that celastrol significantly inhibited ferroptosis in neurons and oligodendrocytes and reduced the accumulation of ROS. Finally, we found that celastrol could inhibit ferroptosis by up-regulating the Nrf2-xCT-GPX4 axis to repair SCI.

CONCLUSION

Celastrol effectively inhibits ferroptosis after SCI by upregulating the Nrf2-xCT-GPX4 axis, reducing the production of lipid ROS, protecting the survival of neurons and oligodendrocytes, and improving the functional recovery.

CircRNA CDR1as affects functional repair after spinal cord injury and regulates fibrosis through the SMAD pathway

Spinal cord injury (SCI) is a complex problem in modern medicine. Fibroblast activation and fibroscarring after SCI impede nerve recovery. Non-coding RNA plays an important role in the progression of many diseases, but the study of its role in the progression of spinal fibrosis is still emerging. Here, we investigated the function of circular RNAs, specifically antisense to the cerebellar degeneration-related protein 1 (CDR1as), in spinal fibrosis and characterized its molecular mechanism and pathophysiology. The presence of CDR1as in the spinal cord was verified by sequencing and RNA expression assays. The effects of inhibition of CDR1as on scar formation, inflammation and nerve regeneration after spinal cord injury were investigated in vivo and in vitro. Further, gene expression of miR-7a-5p and protein expression of transforming Growth Factor Beta Receptor II (TGF-βR2) were measured to evaluate their predicted interactions with CDR1as. The regulatory effects and activation pathways were subsequently verified by miR-7a-5p inhibitor and siCDR1as. These results indicate that CDR1as/miR-7a-5p/TGF-βR2 interactions may exert scars and nerves functions and suggest potential therapeutic targets for treating spinal fibrotic diseases.

Research hotspots and trends of microRNAs in spinal cord injury: a comprehensive bibliometric analysis

Background

Spinal cord injury (SCI) is a nervous system disease leading to motor and sensory dysfunction below the injury level, and can result in paralysis. MicroRNAs (miRNAs) play a key role in SCI treatment, and related research provides insights for SCI diagnosis and treatment. Bibliometrics is an important tool for literature statistics and evaluation, objectively summarizing multidimensional information. This study comprehensively overviews the field through bibliometric analysis of miRNA and SCI research, providing contemporary resources for future collaboration and clinical treatment.

Materials and methods

In this study, we searched the Web of Science Core Collection (WOSCC) database. After careful screening and data import, we extracted annual publications, citation counts, countries, institutions, authors, journals, highly cited articles, co-cited articles, keywords, and H-index. Bibliometrics and visualization analyses employed VOSviewer, CiteSpace, the R package "bibliometrix," and online analytic platforms. Using Arrowsmith, we determined miRNA-SCI relationships and discussed potential miRNA mechanisms in SCI.

Results

From 2008 to 2024, the number of related papers increased annually, reaching 754. The number of yearly publications remained high and entered a period of rapid development. Researchers from 50 countries/regions, 802 institutions, 278 journals, and 3,867 authors participated in the field. Currently, China has advantages in the number of national papers, citations, institutions, and authors. However, it is necessary to strengthen cooperation among different authors, institutions, and countries to promote the production of important academic achievements. The research in the field currently focuses on nerve injury, apoptosis, and gene expression. Future research directions mainly involve molecular mechanisms, clinical trials, exosomes, and inflammatory reactions.

Conclusion

Overall, this study comprehensively analyzes the research status and frontier of miRNAs in SCI. A systematic summary provides a complete and intuitive understanding of the relationship between SCI and miRNAs. The presented findings establish a basis for future research and clinical application in this field.

Inhibition of CD44 suppresses the formation of fibrotic scar after spinal cord injury via the JAK2/STAT3 signaling pathway

Fibrotic scar is one of the main impediments to axon regeneration following spinal cord injury (SCI). In this study, we found that CD44 was upregulated during the formation of fibrotic scar, and blocking CD44 by IM7 caused downregulation of fibrosis-related extracellular matrix proteins at both 2 and 12 weeks post-spinal cord injury. More Biotinylated dextran amine (BDA)-traced corticospinal tract axons crossed the scar area and extended into the distal region after IM7 administration. A recovery of motor and sensory function was observed based on Basso Mouse Scale (BMS) scores and tail-flick test. In vitro experiments revealed that inhibiting CD44 and JAK2/STAT3 signaling pathway decreased the proliferation, differentiation, and migration of fibroblasts induced by the inflammatory supernatant. Collectively, these findings highlight the critical role of CD44 and its downstream JAK2/STAT3 signaling pathway in fibrotic scar formation, suggesting a potential therapeutic target for SCI.

The TGFβ1/SMADs/Snail1 signaling axis mediates pericyte-derived fibrous scar formation after spinal cord injury

AIMS

The deposition of fibrous scars after spinal cord injury (SCI) affects axon regeneration and the recovery of sensorimotor function. It has been reported that microvascular pericytes in the neurovascular unit are the main source of myofibroblasts after SCI, but the specific molecular targets that regulate pericyte participation in the formation of fibrous scars remain to be clarified.

METHODS

In this study, a rat model of spinal cord dorsal hemisection injury was used. After SCI, epigallocatechin gallate (EGCG) was intraperitoneally injected to block the TGFβ1 signaling pathway or LV-Snail1-shRNA was immediately injected near the core of the injury using a microsyringe to silence Snail1 expression. Western blotting and RT-qPCR were used to analyze protein expression and transcription levels in tissues. Nissl staining and immunofluorescence analysis were used to analyze neuronal cell viability, scar tissue, and axon regeneration after SCI. Finally, the recovery of hind limb function after SCI was evaluated.

RESULTS

The results showed that targeted inhibition of Snail1 could block TGFβ1-induced pericyte-myofibroblast differentiation in vitro. In vivo experiments showed that timely blockade of Snail1 could reduce fibrous scar deposition after SCI, promote axon regeneration, improve neuronal survival, and facilitate the recovery of lower limb motor function.

CONCLUSION

In summary, Snail1 promotes the deposition of fibrous scars and inhibits axonal regeneration after SCI by inducing the differentiation of pericytes into myofibroblasts. Snail1 may be a promising therapeutic target for SCI.

TGF-β signaling pathway in spinal cord injury: Mechanisms and therapeutic potential

Spinal cord injury (SCI) is a highly disabling central nervous system injury with a complex pathological process, resulting in severe sensory and motor dysfunction. The current treatment modalities only alleviate its symptoms and cannot effectively intervene or treat its pathological process. Many studies have reported that the transforming growth factor (TGF)-β signaling pathway plays an important role in neuronal differentiation, growth, survival, and axonal regeneration after central nervous system injury. Furthermore, the TGF-β signaling pathway has a vital regulatory role in SCI pathophysiology and neural regeneration. Following SCI, regulation of the TGF-β signaling pathway can suppress inflammation, reduce apoptosis, prevent glial scar formation, and promote neural regeneration. Due to its role in SCI, the TGF-β signaling pathway could be a potential therapeutic target. This article reported the pathophysiology of SCI, the characteristics of the TGF-β signaling pathway, the role of the TGF-β signaling pathway in SCI, and the latest evidence for targeting the TGF-β signaling pathway for treating SCI. In addition, the limitations and difficulties in TGF-β signaling pathway research in SCI are discussed, and solutions are provided to address these potential challenges. We hope this will provide a reference for the TGF-β signaling pathway and SCI research, offering a theoretical basis for targeted therapy of SCI.

microRNA as biomarkers in tuberculosis: a new emerging molecular diagnostic solution

Tuberculosis (TB) caused by Mycobacterium tuberculosis is a lethal infectious disease that is prevalent worldwide. During TB infection, host microRNAs change their expression in the form of up/down-regulation. The identification of unique host microRNAs during TB could serve as potential biomarkers in the early detection of TB. microRNAs fulfill the required criteria for being an ideal biomarker, such as sensitivity, high specificity, and accessibility. Therefore, the recognition of potential host microRNAs can be valuable for the diagnosis of TB. The field of miRNA biomarkers in TB requires more extensive research to identify potential biomarkers. This review provides an overview of the biogenesis and biological functions of microRNAs and presents the findings of various studies on the identification of potential biomarkers for TB. Research momentum is gaining in this field and we anticipate that miRNAs will become a routine approach in the development of reliable diagnostic and specific therapeutic interventions in future.

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.

Fingolimod (FTY720) Hinders Interferon-γ-Mediated Fibrotic Scar Formation and Facilitates Neurological Recovery After Spinal Cord Injury

Following spinal cord injury (SCI), fibrotic scar inhibits axon regeneration and impairs neurological function recovery. It has been reported that T cell-derived interferon (IFN)-γ plays a pivotal role in promoting fibrotic scarring in neurodegenerative disease. However, the role of IFN-γ in fibrotic scar formation after SCI has not been declared. In this study, a spinal cord crush injury mouse was established. Western blot and immunofluorescence showed that IFN-γ was surrounded by fibroblasts at 3, 7, 14, and 28 days post-injury. Moreover, IFN-γ is mainly secreted by T cells after SCI. Further, in situ injection of IFN-γ into the normal spinal cord resulted in fibrotic scar formation and inflammation response at 7 days post-injection. After SCI, the intraperitoneal injection of fingolimod (FTY720), a sphingosine-1-phosphate receptor 1 (S1PR1) modulator and W146, an S1PR1 antagonist, significantly reduced T cell infiltration, attenuating fibrotic scarring via inhibiting IFN-γ/IFN-γR pathway, while in situ injection of IFN-γ diminished the effect of FTY720 on reducing fibrotic scarring. FTY720 treatment inhibited inflammation, decreased lesion size, and promoted neuroprotection and neurological recovery after SCI. These findings demonstrate that the inhibition of T cell-derived IFN-γ by FTY720 suppressed fibrotic scarring and contributed to neurological recovery after SCI.

Building a pathway to recovery: Targeting ECM remodeling in CNS injuries

Extracellular matrix (ECM) is a complex and dynamic network of proteoglycans, proteins, and other macromolecules that surrounds cells in tissues. The ECM provides structural support to cells and plays a critical role in regulating various cellular functions. ECM remodeling is a dynamic process involving the breakdown and reconstruction of the ECM. This process occurs naturally during tissue growth, wound healing, and tissue repair. However, in the context of central nervous system (CNS) injuries, dysregulated ECM remodeling can lead to the formation of fibrotic and glial scars. CNS injuries encompass various traumatic events, including concussions and fractures. Following CNS trauma, the formation of glial and fibrotic scars becomes prominent. Glial scars primarily consist of reactive astrocytes, while fibrotic scars are characterized by an abundance of ECM proteins. ECM remodeling plays a pivotal and tightly regulated role in the development of these scars after spinal cord and brain injuries. Various factors like ECM components, ECM remodeling enzymes, cell surface receptors of ECM molecules, and downstream pathways of ECM molecules are responsible for the remodeling of the ECM. The aim of this review article is to explore the changes in ECM during normal physiological conditions and following CNS injuries. Additionally, we discuss various approaches that target various factors responsible for ECM remodeling, with a focus on promoting axon regeneration and functional recovery after CNS injuries. By targeting ECM remodeling, it may be possible to enhance axonal regeneration and facilitate functional recovery after CNS injuries.

Pharmacotherapies to prevent epidural fibrosis after laminectomy: a systematic review of in vitro and in vivo animal models

BACKGROUND CONTEXT

Excessive production of epidural fibrosis in the nerve root can be a pain source after laminectomy. Pharmacotherapy is a minimally invasive treatment option to attenuate epidural fibrosis by suppressing proliferation and activation of fibroblasts, inflammation, and angiogenesis, and inducing apoptosis.

PURPOSE

We reviewed and tabulated pharmaceuticals with their respective signaling axes implicated in reducing epidural fibrosis. Additionally, we summarized current literature for the feasibility of novel biologics and microRNA to lessen epidural fibrosis.

STUDY DESIGN/SETTING

Systematic Review.

METHODS

According to the PRISMA guidelines, we systematically reviewed the literature in October 2022. The exclusion criteria included duplicates, nonrelevant articles, and insufficient detail of drug mechanism.

RESULTS

We obtained a total of 2,499 articles from PubMed and Embase databases. After screening the articles, 74 articles were finally selected for the systematic review and classified based on the functions of drugs and microRNAs which included inhibition of fibroblast proliferation and activation, pro-apoptosis, anti-inflammation, and antiangiogenesis. In addition, we summarized various pathways to prevent epidural fibrosis.

CONCLUSION

This study allows a comprehensive review of pharmacotherapies to prevent epidural fibrosis during laminectomy.

CLINICAL SIGNIFICANCE

We expect that our review would enable researchers and clinicians to better understand the mechanism of anti-fibrosis drugs for the clinical application of epidural fibrosis therapies.

The Potential of miR-21 in Stem Cell Differentiation and its Application in Tissue Engineering and Regenerative Medicine

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two important types of non-coding RNAs that are not translated into protein. These molecules can regulate various biological processes, including stem cell differentiation and self-renewal. One of the first known miRNAs in mammals is miR-21. Cancer-related studies have shown that this miRNA has proto-oncogene activity and is elevated in cancers. However, it is confirmed that miR-21 inhibits stem cell pluripotency and self-renewal and induces differentiation by targeting various genes. Regenerative medicine is a field of medical science that tries to regenerate and repair damaged tissues. Various studies have shown that miR-21 plays an essential role in regenerative medicine by affecting stem cell proliferation and differentiation. In this review, we will discuss the function of miR-21 in regenerative medicine of the liver, nerve, spinal cord, wound, bone, and dental tissues. In addition, the function of natural compounds and lncRNAs will be analyzed as potential regulators of miR-21 expression in regenerative medicine.

Tackling the glial scar in spinal cord regeneration: new discoveries and future directions

Axonal regeneration and functional recovery are poor after spinal cord injury (SCI), typified by the formation of an injury scar. While this scar was traditionally believed to be primarily responsible for axonal regeneration failure, current knowledge takes a more holistic approach that considers the intrinsic growth capacity of axons. Targeting the SCI scar has also not reproducibly yielded nearly the same efficacy in animal models compared to these neuron-directed approaches. These results suggest that the major reason behind central nervous system (CNS) regeneration failure is not the injury scar but a failure to stimulate axon growth adequately. These findings raise questions about whether targeting neuroinflammation and glial scarring still constitute viable translational avenues. We provide a comprehensive review of the dual role of neuroinflammation and scarring after SCI and how future research can produce therapeutic strategies targeting the hurdles to axonal regeneration posed by these processes without compromising neuroprotection.

Intranasal Delivery of miR133b in a NEO100-Based Formulation Induces a Healing Response in Spinal Cord-Injured Mice

Despite important advances in the pre-clinical animal studies investigating the neuroinhibitory microenvironment at the injury site, traumatic injury to the spinal cord remains a major problem with no concrete response. Here, we examined whether (1) intranasal (IN) administration of miR133b/Ago2 can reach the injury site and achieve a therapeutic effect and (2) NEO100-based formulation of miR133b/Ago2 can improve effectiveness. 24 h after a cervical contusion, C57BL6 female mice received IN delivery of miR133b/Ago2 or miR133b/Ago2/NEO100 for 3 days, one dose per day. The pharmacokinetics of miR133b in the spinal cord lesion was determined by RT-qPCR. The role of IN delivery of miR133b on motor function was assessed by the grip strength meter (GSM) and hanging tasks. The activity of miR133b at the lesion site was established by immunostaining of fibronectin 1 (FN1), a miR133b target. We found that IN delivery of miR133b/Ago2 (1) reaches the lesion scar and co-administration of miR133b with NEO100 facilitated the cellular uptake; (2) enhanced the motor function and addition of NEO100 potentiated this effect and (3) targeted FN1 expression at the lesion scar. Our results suggest a high efficacy of IN delivery of miR133b/Ago2 to the injured spinal cord that translates to improved healing with NEO100 further potentiating this effect.

Expression Profiles of Long Noncoding RNAs and Messenger RNAs in a Rat Model of Spinal Cord Injury

Spinal cord injury (SCI) is a serious disorder of the central nervous system with a high disability rate. Long noncoding RNAs (lncRNAs) are reported to mediate many biological processes. The aim of this study was to explore lncRNA and mRNA expression profiles and functional networks after SCI. Differentially expressed genes between SCI model rats and sham controls were identified by microarray assays and analyzed by functional enrichment. Key lncRNAs were identified using a support vector machine- (SVM-) recursive feature elimination (RFE) algorithm. A trans and cis regulation model was used to analyze the regulatory relationships between lncRNAs and their targets. An lncRNA-related ceRNA network was established. We identified 5465 differentially expressed lncRNAs (DE lncRNAs) and 8366 differentially expressed mRNAs (DE mRNAs) in the SCI group compared with the sham group (fold change > 2.0, p < 0.05). Four genes were confirmed by qRT-PCR which were consistent with the microarray data. GSEA analysis showed that most marked changes occurred in pathways related to immune inflammation and nerve cell function, including cytokine-cytokine receptor interaction, neuroactive ligand-receptor interaction, and GABAergic synapse. Enrichment analysis identified 30 signaling pathways, including those associated with immune inflammation response. A total of 40 key lncRNAs were identified using the SVM-RFE algorithm. A key lncRNA-mRNAs coexpression network was generated for 230 951 lncRNA-mRNA pairs with half showing positive correlations. Several key DE lncRNAs were predicted to have "cis"- or "trans"-regulated target genes. The transcription factors, Sp1, JUN, and SOX10, may regulate the interaction between XR_001837123.1 and ETS 1. In addition, five pairs of ceRNA regulatory sequences were constructed. Many mRNAs and lncRNAs were found to be dysregulated after SCI. Bioinformatic analysis showed that DE lncRNAs may play crucial roles in SCI. It is anticipated that these findings will provide new insights into the underlying mechanisms and potential therapeutic targets for SCI.

Andrographolide contributes to spinal cord injury repair via inhibition of apoptosis, oxidative stress and inflammation

Background: Spinal cord injury (SCI) is a common disorder of the central nervous system with considerable socio-economic burden. Andrographolide (Andro), the main active component of Andrographis paniculata, has exhibited neuroprotective effects in different models of neurological diseases. The aim of this study was to evaluate the neuroprotective effects of Andro against SCI and explore the related mechanisms.

Methods: SCI was induced in rats by the Allen method, and the modeled animals were randomly divided into sham-operated, SCI, SCI + normal saline (NS) and SCI + Andro groups. The rats were injected intraperitoneally with Andro (1 mg/kg) or the same volume of NS starting day one after the establishment of the SCI model for 28 consecutive days. Post-SCI tissue repair and functional recovery were evaluated by measuring the spinal cord water content, footprint tests, Basso-Beattie-Bresnahan (BBB) scores, hematoxylin-eosin (HE) staining and Nissl staining. Apoptosis, oxidative stress and inflammation, as well as axonal regeneration and remyelination were analyzed using suitable markers. The in vitro model of SCI was established by treating cortical neurons with H₂O₂. The effects of Andro on apoptosis, oxidative stress and inflammation were evaluated as indicated.

Results: Andro treatment significantly improved tissue repair and functional recovery after SCI by reducing apoptosis, oxidative stress and inflammation through the nuclear factor E2-related factor 2/heme oxygenase-1 (Nrf-2/HO-1) and nuclear factor-kappa B (NF-κB) signaling pathways. Furthermore, Andro treatment promoted M2 polarization of the microglial cells and contributed to axonal regeneration and remyelination to improve functional recovery after SCI. In addition, Andro also attenuated apoptosis, oxidative stress and inflammation in H₂O₂-stimulated cortical neurons in vitro.

Conclusion: Andro treatment alleviated SCI by reducing apoptosis, oxidative stress and inflammation in the injured tissues and cortical neurons, and promoted axonal regeneration and remyelination for functional recovery.

Apigenin inhibits fibrous scar formation after acute spinal cord injury through TGFβ/SMADs signaling pathway

AIM

To investigate the effect of apigenin on fibrous scar formation after mouse spinal cord injury (SCI).

METHODS

The pneumatic impactor strike method was used to establish an SCI model. Mice were intraperitoneally injected with 5 mg/kg or 20 mg/kg apigenin daily for 28 days after SCI. The Basso Mouse Scale (BMS) score, hematoxylin-eosin staining, and immunohistochemical staining were used to assess the effect of apigenin on scar formation and motor function recovery. Western blotting and qRT-PCR were used to detect the expression of fibrosis-related parameters in spinal cord tissue homogenates. NIH-3 T3 cells and mouse primary spinal cord fibroblasts, α-Smooth muscle actin (α-SMA), collagen 1, and fibronectin were used to evaluate apigenin's effect in vitro. Western blotting and immunofluorescence techniques were used to study the effect of apigenin on TGFβ/SMADs signaling.

RESULTS

Apigenin inhibited fibrous scar formation in the mouse spinal cord and promoted the recovery of motor function. It reduced the expression of fibroblast-related parameters and increased the content of nerve growth factor in vivo, decreasing myofibroblast activation and collagen fiber formation by inhibiting TGFβ-induced SMAD2/3 phosphorylation and nuclear translocation in vitro.

CONCLUSION

Apigenin inhibits fibrous scar formation after SCI by decreasing fibrosis-related factor expression through TGFβ/SMADs signaling.

MiRNAs as Promising Translational Strategies for Neuronal Repair and Regeneration in Spinal Cord Injury

Spinal cord injury (SCI) represents a devastating injury to the central nervous system (CNS) that is responsible for impaired mobility and sensory function in SCI patients. The hallmarks of SCI include neuroinflammation, axonal degeneration, neuronal loss, and reactive gliosis. Current strategies, including stem cell transplantation, have not led to successful clinical therapy. MiRNAs are crucial for the differentiation of neural cell types during CNS development, as well as for pathological processes after neural injury including SCI. This makes them ideal candidates for therapy in this condition. Indeed, several studies have demonstrated the involvement of miRNAs that are expressed differently in CNS injury. In this context, the purpose of the review is to provide an overview of the pre-clinical evidence evaluating the use of miRNA therapy in SCI. Specifically, we have focused our attention on miRNAs that are widely associated with neuronal and axon regeneration. “MiRNA replacement therapy” aims to transfer miRNAs to diseased cells and improve targeting efficacy in the cells, and this new therapeutic tool could provide a promising technique to promote SCI repair and reduce functional deficits.

SU16f inhibits fibrotic scar formation and facilitates axon regeneration and locomotor function recovery after spinal cord injury by blocking the PDGFRβ pathway

Background

Excessively deposited fibrotic scar after spinal cord injury (SCI) inhibits axon regeneration. It has been reported that platelet-derived growth factor receptor beta (PDGFRβ), as a marker of fibrotic scar-forming fibroblasts, can only be activated by platelet-derived growth factor (PDGF) B or PDGFD. However, whether the activation of the PDGFRβ pathway can mediate fibrotic scar formation after SCI remains unclear.

Methods

A spinal cord compression injury mouse model was used. In situ injection of exogenous PDGFB or PDGFD in the spinal cord was used to specifically activate the PDGFRβ pathway in the uninjured spinal cord, while intrathecal injection of SU16f was used to specifically block the PDGFRβ pathway in the uninjured or injured spinal cord. Immunofluorescence staining was performed to explore the distributions and cell sources of PDGFB and PDGFD, and to evaluate astrocytic scar, fibrotic scar, inflammatory cells and axon regeneration after SCI. Basso Mouse Scale (BMS) and footprint analysis were performed to evaluate locomotor function recovery after SCI.

Results

We found that the expression of PDGFD and PDGFB increased successively after SCI, and PDGFB was mainly secreted by astrocytes, while PDGFD was mainly secreted by macrophages/microglia and fibroblasts. In addition, in situ injection of exogenous PDGFB or PDGFD can lead to fibrosis in the uninjured spinal cord, while this profibrotic effect could be specifically blocked by the PDGFRβ inhibitor SU16f. We then treated the mice after SCI with SU16f and found the reduction of fibrotic scar, the interruption of scar boundary and the inhibition of lesion and inflammation, which promoted axon regeneration and locomotor function recovery after SCI.

Conclusions

Our study demonstrates that activation of PDGFRβ pathway can directly induce fibrotic scar formation, and specific blocking of this pathway would contribute to the treatment of SCI.

Identification and coregulation pattern analysis of long noncoding RNAs following subacute spinal cord injury

Long noncoding RNAs (lncRNAs) have been demonstrated to play critical regulatory roles in posttranscriptional and transcriptional regulation in eukaryotic cells. However, the characteristics of many lncRNAs, particularly their expression patterns in the lesion epicenter of spinal tissues following subacute spinal cord injury (SCI), remain unclear. In this study, we determined the expression profiles of lncRNAs in the lesion epicenter of spinal tissues after traumatic SCI and predicted latent regulatory networks. Standard Allen's drop surgery was conducted on mice, and hematoxylin and eosin staining was used to observe the damaged area. High-throughput sequencing was performed to identify the differential expression profiles of lncRNAs. Quantitative real-time polymerase chain reaction was conducted to evaluate the quality of the sequencing results. Bioinformatics analyses, including Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis, coexpression analysis, and protein-protein interaction analysis, were performed. Targeted binding of lncRNA-miRNA-mRNA was predicted by TargetScan and miRanda. A total of 230 differentially expressed lncRNAs were identified and preliminarily verified, and some potential regulatory networks were constructed. These findings improve our understanding of the mechanisms underlying subacute SCI; differentially expressed lncRNAs are closely involved in pathophysiological processes by regulating multiple pathways. Further studies are essential for revealing the exact mechanism underlying competing endogenous RNA pathways in vivo and in vitro.

Micro RNAs as potential biomarkers in tuberculosis: A systematic review

Tuberculosis (TB) remains a major infectious disease across the globe. With increasing TB infections and a rise in multi-drug resistance, rapid diagnostic modalities are required to achieve TB control. Radiological investigations and microbiological tests (microscopic examination, cartridge-based nucleic acid amplification tests, and cultures) are most commonly used to diagnose TB. Histopathological/cytopathological examinations are also required for an accurate diagnosis in many patients. The causative agent, Mycobacterium tuberculosis (Mtb), is known to circumvent the host's immune system. Circulating microRNAs (miRNAs) play a crucial role in biological pathways and can be used as a potential biomarker to detect tuberculosis. miRNAs are small non-coding RNAs and negatively regulate gene expression during post-transcriptional regulation. The differential expression of miRNAs in multiple clinical samples in tuberculosis patients may be helpful as potential disease biomarkers. This review summarizes the literature on miRNAs in various clinical samples as biomarkers for TB diagnosis.

Apoptotic bodies extracted from adipose mesenchymal stem cells carry microRNA-21-5p to induce M2 polarization of macrophages and augment skin wound healing by targeting KLF6

BACKGROUND

Adipose-derived mesenchymal stem cells (adMSCs) are suggested as potential tools for the treatment of regenerative diseases, including tissue repair. This study aimed to explore the function of adMSC-derived apoptotic bodies in skin wound healing and the molecules of action.

METHODS

The acquired adMSCs and their-derived apoptotic bodies were identified. A murine model of full-thickness skin wounds was treated with apoptotic bodies. The wound healing process of mice and the pathological changes in wound tissues were examined. Ana-1 macrophages were treated with lipopolysaccharide (LPS) and apoptotic bodies for in vitro experiments. Polarization of macrophages was examined by immunofluorescence staining of the specific biomarkers and ELISA kits. Dermal microvascular endothelial cells (DMECs) or dermal fibroblasts (DFs) were co-cultured with apoptotic bodies or the LPS- and apoptotic bodies-treated Ana-1 cells. Downstream molecules mediated by apoptotic bodies were screened by microarray and bioinformatic analyses.

RESULTS

Apoptotic bodies treatment accelerated skin wound healing in mice and promoted formation of granulation tissues and blood vessels in wound tissues. Apoptotic bodies treatment induced M2 polarization of macrophages. The angiogenesis ability of DMECs, and the viability and migration of DFs were increased when co-cultured with the apoptotic bodies-treated Ana-1 cells. MicroRNA (miR)-21-5p was abundantly expressed in ABs, and kruppel like factor 6 (KLF6) mRNA was confirmed as a target of miR-21-5p. Overexpression of KLF6 reduced M2 polarization of macrophages and blocked the promoting effect of apoptotic bodies on wound healing in vitro and in vivo.

CONCLUSION

miR-21-5p carried by adMSC-derived apoptotic bodies targets KLF6 to induce M2 polarization of macrophages and augment skin wound healing.

Down-regulating Circular RNA Prkcsh suppresses the inflammatory response after spinal cord injury

Circular RNAs (circRNAs) are a class of conserved, endogenous non-coding RNAs that are involved in transcriptional and post-transcriptional gene regulation and are highly enriched in the nervous system. They participate in the survival and differentiation of multiple nerve cells, and may even promote the recovery of neurological function after stroke. However, their role in the inflammatory response after spinal cord injury remains unclear. In the present study, we established a mouse model of T9 spinal cord injury using the modified Allen’s impact method, and identified 16,013 circRNAs and 960 miRNAs that were differentially expressed after spinal cord injury. Of these, the expression levels of circPrkcsh were significantly different between injured and sham-treated mice. We then treated astrocytes with tumor necrosis factor-α in vitro to simulate the inflammatory response after spinal cord injury. Our results revealed an elevated expression of circPrkcsh with a concurrent decrease in miR-488 expression in injured cells. We also found that circPrkcsh regulated the expression of the inflammation-related gene Ccl2. Furthermore, in tumor necrosis factor-α-treated astrocytes, circPrkcsh knockdown decreased the expression of Ccl2 by upregulating miR-488 expression, and reduced the secretion of inflammatory cytokines in vitro. These findings suggest that differentially expressed circRNAs participate in the inflammatory response after spinal cord injury and act as the regulators of certain microRNAs. Furthermore, circPrkcsh may be used as an miR-488 sponge to regulate Ccl2 expression, which might provide a new potential therapy for SCI. The study was approved by the Animal Ethics Committee of Shandong University of China (approval No. KYLL-20170303) on March 3, 2017.

The role of TGF-β or BMPR2 signaling pathway-related miRNA in pulmonary arterial hypertension and systemic sclerosis

Pulmonary arterial hypertension (PAH) is a severe complication of connective tissue disease (CTD), causing death in systemic sclerosis (SSc). The past decade has yielded many scientific insights into microRNA (miRNAs) in PAH and SSc. This growth of knowledge has well-illustrated the complexity of microRNA (miRNA)-based regulation of gene expression in PAH. However, few miRNA-related SSc-PAH were elucidated. This review firstly discusses the role of transforming growth factor-beta (TGF-β) signaling and bone morphogenetic protein receptor type II (BMPR2) in PAH and SSc. Secondly, the miRNAs relating to TGF-β and BMPR2 signaling pathways in PAH and SSc or merely PAH were subsequently summarized. Finally, future studies might develop early diagnostic biomarkers and target-oriented therapeutic strategies for SSc-PAH and PAH treatment.

[Inhibition of TGF-β promotes functional recovery of spinal cord injury in mice by reducing fibronectin deposition]

OBJECTIVE

To investigate the effect of transforming growth factor (TGF-β) inhibition on functional recovery of spinal cord injury in mice.

METHODS

Twelve mice were divided into treatment group, control group and sham-operated group (n=4). The mice in the treatment group were subjected to hemisection of the spinal cord and received intraperitoneal injection of TGF-β neutralizing antibody (1D11) 3 times a week (25 μL each time), and those in control group were injected with the vehicle antibody (13C4) following spinal cord hemisection. The sham-operated mice underwent sham operation to expose the spinal cord without hemisection. Four weeks later, the heart of the mice was perfused and 1-2 cm of the spinal cord spanning the injury site was harvested. Immunofluorescence staining of FSP1, fibronectin, and PGP9.5 was performed to assess fibroblast recruitment in the injury area, fibronectin deposition, and neurological recovery. For further verification of the results, we used a mouse model of spinal cord clamp injury to observe the survival of axons and distribution of astrocytes by detecting expressions of 5-HT and GFAP with immunofluorescence assay.

RESULTS

In the hemisection injury model, fibroblasts recruitment and fibronectin deposition in the injured area was significantly reduced and the neurological function was improved in 1D11 treatment group as compared with those in 13C4-treated group (P < 0.05). In the spinal cord clamp injury model, treatment with 1D11, as compared with the 13C4, resulted in significantly increased number of 5-HT-positive axons with extended axonal length and obviously increased the number of GFAP-positive astrocytes in the injured area (P < 0.05).

CONCLUSION

Inhibiting TGF-β after spinal cord injury can reduce the recruitment of fibroblasts and fibronectin deposition to promote recovery of neurological function and repair of the injured spinal cord in mice.

Inhibition of TGF-β repairs spinal cord injury by attenuating EphrinB2 expressing through inducing miR-484 from fibroblast

Spinal cord injury (SCI) can lead to severe loss of motor and sensory function with high disability and mortality. The effective treatment of SCI remains unknown. Here we find systemic injection of TGF-β neutralizing antibody induces the protection of axon growth, survival of neurons, and functional recovery, whereas erythropoietin-producing hepatoma interactor B2 (EphrinB2) expression and fibroblasts distribution are attenuated. Knockout of TGF-β type II receptor in fibroblasts can also decrease EphrinB2 expression and improve spinal cord injury recovery. Moreover, miR-488 was confirmed to be the most upregulated gene related to EphrinB2 releasing in fibroblasts after SCI and miR-488 initiates EphrinB2 expression and physical barrier building through MAPK signaling after SCI. Our study points toward elevated levels of active TGF-β as inducer and promoters of fibroblasts distribution, fibrotic scar formation, and EphrinB2 expression, and deletion of global TGF-β or the receptor of TGF-β in Col1α2 lineage fibroblasts significantly improve functional recovery after SCI, which suggest that TGF-β might be a therapeutic target in SCI.

Downregulation of microRNA-21 contributes to decreased collagen expression in venous malformations via transforming growth factor-β/Smad3/microRNA-21 signaling feedback loop

OBJECTIVE

Venous malformations (VMs) are the most frequent vascular malformations and are characterized by dilated and tortuous veins with a dysregulated vascular extracellular matrix. The purpose of the present study was to investigate the potential involvement of microRNA-21 (miR-21), a multifunctional microRNA tightly associated with extracellular matrix regulation, in the pathogenesis of VMs.

METHODS

The expression of miR-21, collagen I, III, and IV, transforming growth factor-β (TGF-β), and Smad3 (mothers against decapentaplegic homolog 3) was evaluated in VMs and normal skin tissue using in situ hybridization, immunohistochemistry, Masson trichrome staining, and real-time polymerase chain reaction. Human umbilical vein endothelial cells (HUVECs) were used to explore the underlying mechanisms.

RESULTS

miR-21 expression was markedly decreased in the VM specimens compared with normal skin, in parallel with downregulation of collagen I, III, and IV and the TGF-β/Smad3 pathway in VMs. Moreover, our data demonstrated that miR-21 positively regulated the expression of collagens in HUVECs and showed a positive association with the TGF-β/Smad3 pathway in the VM tissues. In addition, miR-21 was found to mediate TGF-β-induced upregulation of collagens in HUVECs. Our data have indicated that miR-21 and the TGF-β/Smad3 pathway could form a positive feedback loop to synergistically regulate endothelial collagen synthesis. In addition, TGF-β/Smad3/miR-21 feedback loop signaling was upregulated in bleomycin-treated HUVECs and VM specimens, which was accompanied by increased collagen deposition.

CONCLUSIONS

To the best of our knowledge, the present study has, for the first time, revealed downregulation of miR-21 in VMs, which might contribute to decreased collagen expression via the TGF-β/Smad3/miR-21 signaling feedback loop. These findings provide new information on the pathogenesis of VMs and might facilitate the development of new therapies for VMs.

Fibrotic Scar After Spinal Cord Injury: Crosstalk With Other Cells, Cellular Origin, Function, and Mechanism

The failure of axonal regeneration after spinal cord injury (SCI) results in permanent loss of sensorimotor function. The persistent presence of scar tissue, mainly fibrotic scar and astrocytic scar, is a critical cause of axonal regeneration failure and is widely accepted as a treatment target for SCI. Astrocytic scar has been widely investigated, while fibrotic scar has received less attention. Here, we review recent advances in fibrotic scar formation and its crosstalk with other main cellular components in the injured core after SCI, as well as its cellular origin, function, and mechanism. This study is expected to provide an important basis and novel insights into fibrotic scar as a treatment target for SCI.

Ameliorative effects of miR-423-5p against polarization of microglial cells of the M1 phenotype by targeting a NLRP3 inflammasome signaling pathway

Spinal cord injury (SCI) causes sensation and motion dysfunction. Activation of microglial cells (MCs) in the central nervous system (CNS) is heterogeneous. Heterogeneous types of MCs can produce cytotoxic or neuroprotective effects, secrete proinflammatory or anti-inflammatory factors. The cytotoxic effect of MCs is one of the reasons for secondary damage after SCI. The NLR family pyrin domain containing 3 (NLRP3) inflammasome is a protein that can recognize pathogen-related molecular patterns or host-derived danger signal molecules, responses to microbial infection, and sterile stressors. SCI triggers activation of the NLRP3 inflammasome in the CNS. We investigated the interaction between miR-423-5p and NLRP3 in MCs polarization after SCI. A rat model of SCI was established by a modified version of Allen's method. Spinal samples were adopted for preparation and sequencing of RNA. We screenedapromising microRNA (miR-423-5p) according to the results. Then, we found that NLRP3 was one of the prediction targets of miR-423-5p. By intervening in expression of miR-423-5p and NLRP3, we observed the different polarization of MCs. We employeda dual-luciferase reporter study, proteomics, and transcriptomicsto ascertain the direct targeting relationship between miR-423-5p and NLRP3. MiR-423-5p expression was decreased significantly after SCI in vivo and in vitro. Upregulation of miR-423-5p expression could prevent MCs from lipopolysaccharide-induced M1 polarization. Knockdown of NLRP3 expression could prevent MCs from lipopolysaccharide-induced M1 polarization. MiR-423-5p inhibited MCs polarization to the M1 phenotype by targeting NLRP3.

Diagnosis and Therapeutic Management of Liver Fibrosis by MicroRNA

Remarkable progress has been made in the treatment and control of hepatitis B and C viral infections. However, fundamental treatments for diseases in which liver fibrosis is a key factor, such as cirrhosis, alcoholic/nonalcoholic steatohepatitis, autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis, are still under development and remain an unmet medical need. To solve this problem, it is essential to elucidate the pathogenesis of liver fibrosis in detail from a molecular and cellular perspective and to develop targeted therapeutic agents based on this information. Recently, microRNAs (miRNAs), functional RNAs of 22 nucleotides, have been shown to be involved in the pathogenesis of liver fibrosis. In addition, extracellular vesicles called “exosomes” have been attracting attention, and research is being conducted to establish noninvasive and extremely sensitive biomarkers using miRNAs in exosomes. In this review, we summarize miRNAs directly involved in liver fibrosis, miRNAs associated with diseases leading to liver fibrosis, and miRNAs related to complications of cirrhosis. We will also discuss the efficacy of each miRNA as a biomarker of liver fibrosis and pathology, and its potential application as a therapeutic agent.

miR-153 attenuates the inflammatory response and oxidative stress induced by spinal cord injury by targeting of NEUROD2

OBJECTIVE

Spinal cord injury (SCI) is a common spine surgical injury that leads to loss of activities of daily living. NEUROD2, a member of the neuroD family, is newly known to play a crucial role in SCI progression. We aimed to investigate the underlying mechanism wherein miR-153 and NEUROD2 modulate the process of SCI.

METHODS

Expression of miR-153 and NEUROD2 in spinal cord in mice of SCI were analyzed employing western blot and qRT-PCR assays. Microglial cells were transfected with mimic of miR-153 or siRNA targeting NEUROD2 to determine the impact of miR-153 and NEUROD2 on SCI induced inflammatory reaction and oxidative stress. A luciferase reporter assay was conducted to verify the regulation of miR-153 on NERUOD2.

RESULTS

MiR-153 expression was decreased in injured spinal cord, while NERUOD2 was increased in a time-dependent manner. Addition of miR-153 mimic or silencing NERUOD2 might significantly inhibit the production of inflammation cytokines and attenuated oxidative stress in microglia cells of SCI. Luciferase reporter assay suggested that NERUOD2 was a direct target of miR-153.

CONCLUSION

We proved that miR-153 attenuated inflammatory response and oxidative stress induced by SCI by targeting of NEUROD2, indicating a protective role in SCI progression.

miR-21a-5p Promotes Inflammation following Traumatic Spinal Cord Injury through Upregulation of Neurotoxic Reactive Astrocyte (A1) Polarization by Inhibiting the CNTF/STAT3/Nkrf Pathway

Reactive astrocytes are implicated in traumatic spinal cord injury (TSCI). Interestingly, naïve astrocytes can easily transform into neurotoxic reactive astrocytes (A1s) with inflammatory stimulation. Previous studies demonstrated that microRNA(miR)-21a-5p was up-regulated in spinal cord tissue after TSCI; however, it is not clear whether this affected reactive astrocyte polarization. Here, we aim to detect the effects of miR-21a-5p on the induction of A1 formation and the underlying mechanisms. Our study found that the expression of miR-21a-5p was significantly increased while that of Cntfr α was decreased, since naïve astrocytes transformed into A1s 3 days post-TSCI; the binding site between miR-21a-5p and Cntfr α was further confirmed in astrocytes. After treatment with CNTF, the levels of A1 markers decreased while that of A2 increased. The expression of A1 markers significantly decreased with the downregulation of miR-21a-5p, while Cntfr α siRNA treatment caused the opposite both in vitro and in vivo. To summarize, miR-21a-5p/Cntfr α promotes A1 induction and might enhance the inflammatory process of TSCI; furthermore, we identified, for the first time, the effect and potential mechanism by which CNTF inhibits naïve astrocytes transformation into A1s. Collectively, our findings demonstrate that targeting miR-21a-5p represents a prospective therapy for promoting the recovery of TSCI.

Circular RNA Plek promotes fibrogenic activation by regulating the miR-135b-5p/TGF-βR1 axis after spinal cord injury

Objectives: The spinal cord rarely repairs itself when damaged; however, methods for encouraging nerves to regrow are on the horizon. Although circular RNAs (circRNAs) contribute to various biological processes, including neuronal processes, their functions in the subacute phase of spinal cord injury (SCI) have not been elucidated. In this study, we identified a novel circRNA, named CircPlek, with increased expression in spinal tissues after SCI.

Materials and Methods: We predicted a regulatory relationship between CircPlek and miR-135b-5p, which showed the most obvious decrease in post-SCI expression. We established the CircPlek/miR-135b-5p/transforming growth factor-beta receptor type I (TGF-βR1) axis using a bioinformatics approach and further evaluated the potential function of the interaction network in vitro.

Results: We confirmed that in TGF-β1-induced fibroblasts, the overexpression of miR-135b-5p or/and inhibition of CircPlek inhibited fibrosis activation via the Smad pathway. Inhibitors of miR-135b-5p had antagonistic effects on CircPlek.

Conclusions: the CircPlek/miR-135b-5p/TGF-βR1 axis may exert important functions in SCI and is a potential therapeutic target.

Research progress on the regulatory role of microRNAs in spinal cord injury

Spinal cord injury (SCI) is a severe CNS injury that results in abnormalities in, or loss of, motor, sensory and autonomic nervous function. miRNAs belong to a new class of noncoding RNA that regulates the production of proteins and biological function of cells by silencing translation or interfering with the expression of target mRNAs. Following SCI, miRNAs related to oxidative stress, inflammation, autophagy, apoptosis and many other secondary injuries are differentially expressed, and these miRNAs play an important role in the progression of secondary injuries after SCI. The purpose of this review is to elucidate the differential expression and functional roles of miRNAs after SCI, thus providing references for further research on miRNAs in SCI.

Central Nervous System Fibroblast-Like Cells in Stroke and Other Neurological Disorders

Fibroblasts are the most common cell type of connective tissues. In the central nervous system (CNS), fibroblast-like cells are mainly located in the meninges and perivascular Virchow-Robin space. The origins of these fibroblast-like cells and their functions in both CNS development and pathological conditions remain largely unknown. In this review, we first introduce the anatomic location and molecular markers of CNS fibroblast-like cells. Next, the functions of fibroblast-like cells in CNS development and neurological disorders, including stroke, CNS traumatic injuries, and other neurological diseases, are discussed. Third, current challenges and future directions in the field are summarized. We hope to provide a synthetic review that stimulates future research on CNS fibroblast-like cells.

Therapeutic miR-21 Silencing Reduces Cardiac Fibrosis and Modulates Inflammatory Response in Chronic Chagas Disease

Chagas disease, caused by the parasite Trypanosoma cruzi (T. cruzi), remains a serious public health problem for which there is no effective treatment in the chronic stage. Intense cardiac fibrosis and inflammation are hallmarks of chronic Chagas disease cardiomyopathy (CCC). Previously, we identified upregulation of circulating and cardiac miR-21, a pro-fibrotic microRNA (miRNA), in subjects with CCC. Here, we explored the potential role of miR-21 as a therapeutic target in a model of chronic Chagas disease. PCR array-based 88 microRNA screening was performed in heart samples obtained from C57Bl/6 mice chronically infected with T. cruzi and serum samples collected from CCC patients. MiR-21 was found upregulated in both human and mouse samples, which was corroborated by an in silico analysis of miRNA-mRNA target prediction. In vitro miR-21 functional assays (gain-and loss-of-function) were performed in cardiac fibroblasts, showing upregulation of miR-21 and collagen expression upon transforming growth factor beta 1 (TGFβ1) and T. cruzi stimulation, while miR-21 blockage reduced collagen expression. Finally, treatment of T. cruzi-infected mice with locked nucleic acid (LNA)-anti-miR-21 inhibitor promoted a significant reduction in cardiac fibrosis. Our data suggest that miR-21 is a mediator involved in the pathogenesis of cardiac fibrosis and indicates the pharmacological silencing of miR-21 as a potential therapeutic approach for CCC.

HBV induces liver fibrosis via the TGF-β1/miR-21-5p pathway

MicroRNA (miR)-21-5p is a newly discovered factor that mediates TGF-β1 signaling. The present study was designed to investigate the role of TGF-β1/miR-21-5p in hepatitis B virus (HBV)-induced liver fibrosis. HBV-infected sodium taurocholate co-transporting polypeptide (NTCP)-transfected Huh7.5.1 cells were co-cultured with LX2 cells to simulate HBV infection in the present study. A total of 29 patients with chronic HBV infection were enrolled. Cells were transfected with miR-21-5p mimic or inhibitor with or without TGF-β1 stimulation. The demographic, biochemical and virological data from the 29 patients were analyzed and liver tissues were collected. miR-21-5p levels and the mRNA and protein expression of α-smooth muscle actin (SMA), collagen type 1 α 1 (CoL1A1), tissue inhibitor of metalloproteinase (TIMP)-1 and Smad from liver cells or tissues were detected by quantitative PCR analysis and western blotting, respectively. Cell viability was observed, and the liver fibrosis score was evaluated. The association between miR-21-5p and liver fibrosis was evaluated by correlation analysis. HBV infection upregulated TGF-β1/miR-21-5p mRNA expression in NTCP-Huh7.5.1 cells compared with mock infection (P<0.05). TGF-β1 incubation significantly increased miR-21-5p levels, as well as the mRNA and protein expression of α-SMA, CoL1A1 and TIMP-1, and reduced Smad7 expression in LX2 cells compared with the normal group, and these effects were counteracted by miR-21-5p inhibitor (P<0.05). miR-21-5p overexpression also contributed to TGF-β1-induced α-SMA, CoL1A1 and TIMP-1 expression in LX2 cells (P<0.05). Co-culture with HBV-infected NTCP-Huh7.5.1 cells upregulated TGF-β1/miR-21-5p activity and CoL1A1 expression in LX2 cells compared with normal control, which were significantly reduced by miR-21-5p inhibitor (P<0.05). miR-21-5p levels were significantly correlated with the liver fibrosis score (r=0.888; P<0.05). These data demonstrated that HBV induced liver fibrosis via the TGF-β1/miR-21-5p pathway and suggested that miR-21-5p may be an effective anti-fibrosis target.

Roles of Non-coding RNAs in Central Nervous System Axon Regeneration

Axons in the central nervous system often fail to regenerate after injury due to the limited intrinsic regeneration ability of the central nervous system (CNS) and complex extracellular inhibitory factors. Therefore, it is of vital importance to have a better understanding of potential methods to promote the regeneration capability of injured nerves. Evidence has shown that non-coding RNAs play an essential role in nerve regeneration, especially long non-coding RNA (lncRNA), microRNA (miRNA), and circular RNA (circRNA). In this review, we profile their separate roles in axon regeneration after CNS injuries, such as spinal cord injury (SCI) and optic nerve injury. In addition, we also reveal the interactive networks among non-coding RNAs.

Role of circular RNA expression in the pathological progression after spinal cord injury

Differential expression of non-coding RNA after traumatic spinal cord injury (TSCI) is closely related to the pathophysiological process. The purposes of this study were to systematically profile and characterize expression of circular RNA (circRNA) in the lesion epicenter of spinal tissues after TSCI, and predict the structure and potential function of the regulatory circRNA/miRNA network. Forty-eight C57BL/6 mice were randomly and equally assigned to two groups: one subjected to TSCI at T8–10 with an Allen’s drop impactor, and a second subjected to laminectomy without TSCI. Spinal cord samples were stained with hematoxylin and eosin, sequenced, and validated. RNA-Seq, Gene Ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis, and network analyses (Targetscan and miRanda) were used to predict and annotate the circRNA/miRNA/mRNA network. Luciferase reporter, quantitative reverse transcription polymerase chain reaction, and western blot assays were used to profile expression and regulation patterns of the network in mouse models of TSCI. Hematoxylin-eosin staining revealed severe damage to the blood-spinal cord barrier after TSCI. Differentially expressed circRNA and miRNA profiles were obtained after TSCI; differentially expressed circRNAs, which were abundant in the cytoplasm, were involved in positive regulation of transcription and protein phosphorylation. miR-135b-5p was the most significantly downregulated miRNA after TSCI; circRNAAbca1 and KLF4 were predicted to be its target circRNA and mRNA, respectively. Subsequently, the circAbca1/miR-135b-5P/KLF4 regulatory axis was predicted and constructed, and its targeted binding was verified. After inhibiting circAbca1, GAP43 expression was upregulated. Differential expression of circRNAs might play an important role after TSCI. circAbca1 plays a neuroinhibitory role by targeted binding of the miR-135b-5P/KLF4 axis. The identified circRNA/miRNA/mRNA network could provide the basis for understanding pathophysiological mechanisms underlying TSCI, as well as guide the formulation of related therapeutic strategies. All animal protocols were approved by the Research Ethics Committee of West China Hospital of China (approval No. 2017128) on May 16, 2017.

A sandwich structured drug delivery composite membrane for improved recovery after spinal cord injury under longtime controlled release

A sandwich structured composite membrane for longtime controlled release of nerve growth factor (NGF) to repair spinal cord injury (SCI) is prepared through electrospray. In this system, PLA film is used as the sealing layer to prevent drug diffusion and provide mechanical support, PLGA microspheres as the sandwich layer to load and controlled release NGF, and chitosan (CS) film as the planting layer to seed bone marrow mesenchymal stem cells (BMSCs). The composite membrane has good biocompatibility and can effectively promote PC-12 cells to differentiate into neurons. In addition, the composite membrane can be directly applied to the injured areas without further damage. The longtime sustained release of NGF guaranteed enough requirement time for SCI repair, which will decrease the administration frequency and improve patient compliance. The administration of BMSCs coupled with the sandwich composite membrane effectively relieves SCI, decreases cavity formation, enhances neuronal regeneration and tissue repair, as well as improves the recovery of locomotor functions. Overall, this present work provides a future perspective for the treatment of SCI by the NGF-loaded sandwich composite membrane with prolonged drug release function.

Necrostatin-1, RIP1/RIP3 inhibitor, relieves transforming growth factor β-induced wound-healing process in formation of hypertrophic scars

BACKGROUND

Hypertrophic scars (HS) are common pathologic processes emerged during wound-healing process. The receptor-interacting protein kinase (RIP) might participate in keloid formation.

AIMS

This study aimed to investigate Necrostatin-1 (Nec-1), a RIP1/RIP3 inhibitor, in the formation of hypertrophic scar.

METHODS

Human hypertrophic scar fibroblasts (HSF) were extracted from patients with hypertrophic scar. Transforming growth factor-β1 (TGF-β1) was performed to induce wound-healing process including cell proliferation (CCK-8, Flow cytometry, and Western blot), migration (Transwell assay, Western blot), collagen production (Western blot), and extracellular matrix dysfunction (Western blotting and immunofluorescence).

RESULTS

Our results reported that Nec-1 inhibited TGF-β1-induced cell proliferation and promoted G0/G1 phase arrest in HSF. In addition, Nec-1 attenuated TGF-β1-induced cell migration and inhibited the expression of MMP2 and MMP9 in TGF-β1-induced HSF. Besides, Nec-1 also reduced TGF-β1-induced collagen production and α-smooth muscle actin expression in HSF.

CONCLUSIONS

The present data in this study showed the potential role of Nec-1 as a novel treatment for HS.

miR-205 inhibits the development of hypertrophic scars by targeting THBS1

Increasing evidence shows that miRNAs are involved in the growth and development of hypertrophic scars. However, the specific mechanism of miR-205 is unclear. Here, we investigated the relationship between miR-205, thrombospondin 1 (THBS1) expression, and hypertrophic scars, and showed that miR-205 inhibits cell proliferation and migration and induces apoptosis. Double luciferase analysis, Western blot, and real-time polymerase chain reaction showed that miR-205 downregulates THBS1 expression and activity. Compared to the control group, miR-205 inhibited hypertrophic scar development. Our findings contribute to a better understanding of the miR-205-THBS1 pathway as a promising therapeutic target for reducing hypertrophic scars.

Genome-wide analysis of acute traumatic spinal cord injury-related RNA expression profiles and uncovering of a regulatory axis in spinal fibrotic scars

Objectives

Long non‐coding RNAs (lncRNAs) are critical for posttranscriptional and transcriptional regulation in eukaryotic cells. However, data on lncRNA expression in the lesion epicentres of spinal tissues after acute traumatic spinal cord injury (ATSCI) are scarce. We aimed to identify lncRNA expression profiles in such centres and predict latent regulatory networks.

Materials and methods

High‐throughput RNA‐sequencing was used to profile the expression and regulatory patterns of lncRNAs, microRNAs and messenger RNAs (mRNAs) in an ATSCI C57BL/6 mouse model. Chromosome distributions, open reading frames (ORFs), transcript abundances, exon numbers and lengths were compared between lncRNAs and mRNAs. Gene ontology, KEGG pathways and binding networks were analysed. The findings were validated by qRT‐PCRs and luciferase assays.

Results

Intronic lncRNAs were the most common differentially expressed lncRNA. Most lncRNAs had <6 exons, and lncRNAs had shorter lengths and lesser ORFs than mRNAs. MiR‐21a‐5p had the most significant differential expression and bound to the differentially expressed lncRNA ENSMUST00000195880. The microRNAs and lncRNAs with significant differential expression were screened, and a lncRNA/miRNA/mRNA interaction network was predicted, constructed and verified.

Conclusions

The regulatory actions of this network may play a role in the pathophysiology of ATSCI. Our findings may lead to better understanding of potential ncRNA biomarkers and confer better therapeutic strategies for ATSCIs.

MiR-21-5p actions at the Smad7 gene during pig ovarian granulosa cell apoptosis

MicroRNAs (miRNAs) are endogenous non-coding RNAs in eukaryotic cells that modulate apoptosis of ovarian granulosa cells (GCs), which is an important cause of mammalian follicular atresia. In the present study, associations were evaluated between miR-21-5p and the extent of Smad7 protein production in regulation of ovarian granulosa cell (pGC) apoptosis. There was detection of miR-21-5p and Smad7 primarily in the cytoplasm and nucleus of pGCs, respectively. When there was an enhanced abundance of miR-21-5p and decreased abundance of Smad7 there were similar effects in pGCs, including inducing proliferation, inhibiting apoptosis, increasing the number of cells in S and G2/M phases, increasing serum estradiol, and decreasing serum progesterone concentrations. Furthermore, the Smad7 mRNA transcript was identified as a target for miR-21-5p actions, with enhanced abundances of miR-21-5p being associated with a lesser abundance of Smad7 mRNA transcript and protein in pGCs. Overall, results from the present study indicate that miR-21-5p has actions on the Smad7 mRNA transcript during the process of ovarian granulosa cell apoptosis in pigs.

Human Adipocyte Conditioned Medium Promotes In Vitro Fibroblast Conversion to Myofibroblasts

Adipocytes and adipose tissue derived cells have been investigated for their potential to contribute to the wound healing process. However, the details of how these cells interact with other essential cell types, such as myofibroblasts/fibroblasts, remain unclear. Using a novel in-vitro 3D human adipocyte/pre-adipocyte spheroid model, we investigated whether adipocytes and their precursors (pre-adipocytes) secrete factors that affect human dermal fibroblast behavior. We found that both adipocyte and pre-adipocyte conditioned medium induced the migration of fibroblasts, but only adipocyte conditioned medium induced fibroblast differentiation into a highly contractile, collagen producing myofibroblast phenotype. Furthermore, adipocyte mediated myofibroblast induction occurred through a TGF-β independent mechanism. Our findings contribute to a better understanding on the involvement of adipose tissue in wound healing, and may help to uncover and develop fat-related wound healing treatments.

Identification of noncoding RNA expression profiles and regulatory interaction networks following traumatic spinal cord injury by sequence analysis

Aim: To systematically profile and characterize the noncoding RNA (ncRNA) expression pattern in the lesion epicenter of spinal tissues after traumatic spinal cord injury (TSCI) and predicted the structure and potential functions of the regulatory networks associated with these differentially expressed ncRNAs and mRNAs.

Results: A total of 498 circRNAs, 458 lncRNAs, 155 miRNAs and 1203 mRNAs were identified in TSCI mice models to be differentially expressed. The regulatory networks associated with these differentially expressed ncRNAs and mRNAs were constructed.

Materials and methods: We used RNA-Seq, Gene ontology (GO), KEGG pathway analysis and co-expression network analyses to profle the expression and regulation patterns of noncoding RNAs and mRNAs of mice models after TSCI. The findings were validated by quantitative real-time PCR (qRT-PCR) and Luciferase assay.

Conclusion: noncoding RNAs might play important roles via the competing endogenous RNA regulation pattern after TSCI, further findings arising from this study will not only expand the understanding of potential ncRNA biomarkers but also help guide therapeutic strategies for TSCI.

Circulating microRNAs as non-invasive biomarkers for hepatitis B virus liver fibrosis

Viruses can alter the expression of host microRNAs (MiRNA s) and modulate the immune response during a persistent infection. The dysregulation of host MiRNA s by hepatitis B virus (HBV) contributes to the proinflammatory and profibrotic changes within the liver. Multiple studies have documented the differential regulation of intracellular and circulating MiRNA s during different stages of HBV infection. Circulating MiRNA s found in plasma and/or extracellular vesicles can integrate data on viral-host interactions and on the associated liver injury. Hence, the detection of circulating MiRNA s in chronic HBV hepatitis could offer a promising alternative to liver biopsy, as their expression is associated with HBV replication, the progression of liver fibrosis, and the outcome of antiviral treatment. The current review explores the available data on miRNA involvement in HBV pathogenesis with an emphasis on their potential use as biomarkers for liver fibrosis.

CNS microRNA profiles: a database for cell type enriched microRNA expression across the mouse central nervous system

microRNAs are short, noncoding RNAs that can regulate hundreds of targets and thus shape the expression landscape of a cell. Similar to mRNA, they often exhibit cell type enriched expression and serve to reinforce cellular identity. In tissue with high cellular complexity, such as the central nervous system (CNS), it is difficult to attribute microRNA changes to a particular cell type. To facilitate interpretation of microRNA studies in these tissues, we used previously generated data to develop a publicly accessible and user-friendly database to enable exploration of cell type enriched microRNA expression. We provide illustrations of how this database can be utilized as a reference as well as for hypothesis generation. First, we suggest a putative role for miR-21 in the microglial spinal injury response. Second, we highlight data indicating that differential microRNA expression, specifically miR-326, may in part explain regional differences in inflammatory cells. Finally, we show that miR-383 expression is enriched in cortical glutamatergic neurons, suggesting a unique role in these cells. These examples illustrate the database’s utility in guiding research towards unstudied regulators in the CNS. This novel resource will aid future research into microRNA-based regulatory mechanisms responsible for cellular phenotypes within the CNS.

[Identification of potential traumatic spinal cord injury related circular RNA-microRNA networks by sequence analysis]

Objective

To systematically profile and characterize the circular RNA (circRNA) and microRNA (miRNA) expression pattern in the lesion epicenter of spinal tissues after traumatic spinal cord injury (TSCI) and predict the structure and potential functions of the regulatory network.

Methods

Forty-eight adult male C57BL/6 mice (weighing, 18-22 g) were randomly divided into the TSCI ( n=24) and sham ( n=24) groups. Mice in the TSCI group underwent T _8-10 vertebral laminectomy and Allen's weight-drop spinal cord injury. Mice in the sham group underwent the same laminectomy without TSCI. The spinal tissues were harvested after 3 days. Some tissues were stained with HE staining to observe the structure. The others were used for sequencing. The RNA-Seq, gene ontology (GO) analysis, and circRNA-miRNA network analyses (TargetScan and miRanda) were used to profile the expression and regulation patterns of network of mice models after TSCI.

Results

HE staining showed the severe damage to the spinal cord in TSCI group compared with sham group. A total of 17 440 circRNAs and 1 228 miRNAs were identified. The host gene of significant differentially expressed circRNA enriched in the cytoplasm, associated with positive regulation of transcription and protein phosphorylation. mmu-miR-21-5p was the most significant differentially expressed miRNA after TSCI, and circRNA6730 was predicted to be its targeted circRNA. Then a potential regulatory circRNA-miRNA network was constructed.

Conclusion

The significant differentially expressed circRNAs and miRNAs may play important roles after TSCI. A targeted interaction network with mmu-miR-21-5p at the core of circRNA6730 could provide basis of pathophysiological mechanism, as well as help guide therapeutic strategies for TSCI.