MiR-137 inhibited inflammatory response and apoptosis after spinal cord injury via targeting of MK2

The role of apoptosis in spinal cord injury: a bibliometric analysis from 1994 to 2023

Background

Apoptosis after spinal cord injury (SCI) plays a pivotal role in the secondary injury mechanisms, which cause the ultimate neurologic insults. A better understanding of the molecular and cellular basis of apoptosis in SCI allows for improved glial and neuronal survival via the administrations of anti-apoptotic biomarkers. The knowledge structure, development trends, and research hotspots of apoptosis and SCI have not yet been systematically investigated.

Methods

Articles and reviews on apoptosis and SCI, published from 1st January 1994 to 1st Oct 2023, were retrieved from the Web of Science™. Bibliometrix in R was used to evaluate annual publications, countries, affiliations, authors, sources, documents, key words, and hot topics.

Results

A total of 3,359 publications in accordance with the criterions were obtained, which exhibited an ascending trend in annual publications. The most productive countries were the USA and China. Journal of Neurotrauma was the most impactive journal; Wenzhou Medical University was the most prolific affiliation; Cuzzocrea S was the most productive and influential author. "Apoptosis," "spinal-cord-injury," "expression," "activation," and "functional recovery" were the most frequent key words. Additionally, "transplantation," "mesenchymal stemness-cells," "therapies," "activation," "regeneration," "repair," "autophagy," "exosomes," "nlrp3 inflammasome," "neuroinflammation," and "knockdown" were the latest emerging key words, which may inform the hottest themes.

Conclusions

Apoptosis after SCI may cause the ultimate neurological damages. Development of novel treatments for secondary SCI mainly depends on a better understanding of apoptosis-related mechanisms in molecular and cellular levels. Such therapeutic interventions involve the application of anti-apoptotic agents, free radical scavengers, as well as anti-inflammatory drugs, which can be targeted to inhibit core events in cellular and molecular injury cascades pathway.

Different Ways to Die: Cell Death Pathways and Their Association With Spinal Cord Injury

Cell death is a systematic/nonsystematic process of cessation of normal morphology and functional properties of the cell to replace and recycle old cells with new also promoting inflammation in some cases. It is a complicated process comprising multiple pathways. Some are well-explored, and others have just begun to be. The research on appropriate control of cell death pathways after acute and chronic damage of neuronal cells is being widely researched today due to the lack of regeneration and recovering potential of a neuronal cell after sustaining damage and the inability to control the direction of neuronal growth. In the progression and onset of various neurological diseases, impairments in programmed cell death signaling processes, like necroptosis, apoptosis, ferroptosis, pyroptosis, and pathways directly or indirectly linked, like autophagy as in nonprogrammed necrosis, are observed. Spinal cord injury (SCI) involves the temporary or permanent disruption of motor activities due to the death of a neuronal and glial cell in the spinal cord accompanied by axonal degeneration. Recent years have seen a significant increase in research on the intricate biochemical interactions that occur after a SCI. Different cell death pathways may significantly impact the subsequent damage processes that lead to the eventual neurological deficiency after an injury to the spinal cord. A better knowledge of the molecular basis of the involved cell death pathways might help enhance neuronal and glial survival and neurological deficits, promoting a curative path for SCI.

Stem cell-derived exosomes for chronic wound repair

Stem cells possess the capability of self-renewal and multipotency, which endows them with great application potential in wound repair fields. Yet, several problems including immune concerns, ethical debates, and oncogenicity impede the broad and deep advance of stem cell-based products. Recently, owing to their abundant resources, excellent biocompatibility, and ease of being engineered, stem cell-derived exosomes were proved to be promising nanomedicine for curing chronic wounds. What is more, stem cell-derived exosomes are almost the mini record of their maternal cells, which even equipped them with the unique characteristics of stem cells. Chronic wound healing efficacy is dominated by several complicated factors, especially the excessive inflammation conditions and impaired vessels. Therefore, this review tries to concentrate on the current advances of stem cell-derived exosomes for reducing inflammation and promoting angiogenesis in chronic wound healing processes. Last but not least, the existing limitations and future perspectives of stem cell-derived exosomes for chronic wound treatment are also outlined.

Alleviation of Spinal Cord Injury by MicroRNA 137-Overexpressing Bone Marrow Mesenchymal Stem Cell-Derived Exosomes

Bone marrow mesenchymal stem cell (BMMSC) is reported to promote spinal cord injury (SCI) recovery via secreting exosomes to deliver RNAs, proteins, lipids, etc. The present study aimed to investigate the effect of microRNA 137 (miR-137)-overexpressing BMMSC exosomes on SCI rats. BMMSCs were extracted from Sprague-Dawley (SD) rat hind leg bone marrow, and then BMMSC-secreted exosomes were collected. MiR-137 mimic and negative control (NC) mimic were transfected into BMMSCs, and then the corresponding exosomes were collected. Subsequently, SD rats were treated with sham operation + phosphate-buffered saline (PBS), SCI operation + PBS, SCI operation + NC mimic BMMSC exosomes, or SCI operation + miR-137-overexpressing BMMSC exosomes. MiR-137 was downregulated in the spinal cord tissue of SCI rats compared to sham rats. Furthermore, BMMSC exosome injection elevated the Basso, Beattie, and Bresnahan (BBB) scores and neuronal viability and reduced tissue injury and proinflammatory cytokine expression in the spinal cord tissue of SCI rats compared to PBS treatment. Subsequently, miR-137-overexpressing BMMSC exosome injection improved the BBB score and neuron viability, and decreased tissue injury as well as proinflammatory cytokine expression in SCI rats compared to NC-overexpressing BMMSC exosomes. Additionally, miR-137-overexpressing BMMSC exosomes also diminished neuronal apoptosis in the spinal cord tissue of SCI rats compared to NC-overexpressing BMMSC exosomes. In conclusion, miR-137-overexpressing BMMSC exosomes reduce tissue injury and inflammation while improving locomotor capacity and neuronal viability in SCI rats. These findings suggest that miR-137-overexpressing BMMSC exosomes may serve as a treatment option for SCI recovery.

CircRNA3616 knockdown attenuates inflammation and apoptosis in spinal cord injury by inhibiting TLR4/NF-κB activity via sponging miR-137

PURPOSE

The present work focused on exploring the role of circRNA3616 in neuronal inflammation and apoptosis in spinal cord injury (SCI).

METHODS

The SCI mouse model and circRNA3616 knockdown SCI mouse model were established. This work focused on assessing the mouse locomotor function using Basso Mouse Scale (BMS) and BMS subscore. Hematoxylin-eosin (HE) staining and Tunel staining were conducted, while myeloperoxidase (MPO) activity was also detected on spinal cord tissues. We also knocked down circRNA3616 expression in NSC-34 cells. Meanwhile, the SCI cell model was established by oxygen glucose deprivation (OGD) in NSC-34 cells. Moreover, we conducted dual-luciferase reporter gene assay. Flow cytometry (FCM) was conducted to detect SCI cell apoptosis, whereas cell counting kit-8 (CCK-8) assay was performed to analyze cell viability. This study also implemented enzyme-linked immunosorbent assay to detect inflammatory factors in spinal cord tissues, serum, and cells.

RESULTS

CircRNA3616 knockdown reduced the damage, inflammatory response, apoptosis, and MPO activity in SCI mouse serum and spinal cord tissues. CircRNA3616 knockdown increased BMS and BMS subscore of SCI mice. CircRNA3616 up-regulated TLR4 expression by sponging miR-137. CircRNA3616 knockdown inhibited the TLR4, p-IkBα, p-p65/p65 protein expression, while promoting IkBα protein expression within SCI mouse spinal cord. TLR4 reversed circRNA3616 knockdown-induced inhibition on NF-κB pathway activity in SCI cells. CircRNA3616 knockdown attenuated neuronal cell inflammation and apoptosis via TLR4/NF-κB pathway after SCI.

CONCLUSION

CircRNA3616 silencing attenuates inflammation and apoptosis in SCI by inhibiting TLR4/NF-κB activity via sponging miR-137. CircRNA3616 is the possible anti-SCI therapeutic target.

miR-129-5p Induces Cell Apoptosis and Inhibits Inflammation by Inflammatory Signaling to Alleviate Spinal Cord Injury (SCI)

Spinal cord injury (SCI) is a spinal cord nerve dysfunction secondary to trauma. Until now, still no appropriate drug with unclear etiology. Therefore, it is to develop effective SCI treatment methods. Herein, we intended to detect the impact of miR-129-5p in SCI After establishment of a mouse SCI model, the animals received intrathecal injection of agomir-miR-129-5p or normal saline. Then, the miR-129-5p’s effect was evaluated by assessing motor function, spinal cord tissue edema, apoptosis and inflammation of mice upon treatments and potential targeted pathways of the miRNA were detected. Overexpressed miR-129-5p facilitated the wound healing with less spare tissue and water content. Additionally, overexpressed miR-129-5p suppressed the in vivo inflammation with decreased apoptotic rate of neurons. As SCI induced increased expression of HMGB1, TLR4, and NF-κB in tissues, but the presence of miR-129-5p reversed the expressions. Collectively, this study elucidate miR-129-5p significantly improves inflammatory response and apoptosis, thereby improving the condition of SCI. These findings might provide a new theory for the disorder, and promote the research progress on the disease.

MicroRNA-137-mediated lysine demethylase 4A regulates the recovery of spinal cord injury via the SFRP4-Wnt/β-Catenin axis

OBJECTIVE

Spinal cord injury (SCI) causes great harm to the normal life of patients. Histone demethylase is involved in many biological processes, including SCI. Hence, this study explored the role and mechanism of histone lysine demethylase 4A (KDM4A) in SCI.

METHODS

The acute SCI (ASCI) rat model was established after spinal compression and the SCI neuronal model was induced via treating PC12 cells with lipopolysaccharide (LPS). KDM4A expression during SCI was detected. The microRNA (miRNA) targeting KDM4A was predicted and verified. The miRNA and KDM4A expression patterns were intervened in LPS-stimulated PC12 cells to evaluate their combined effects on neuronal cells in SCI. The downstream pathways of KDM4A were predicted, and SFRP4 and H3K9me3 expressions were determined. After the intervention of SFRP4 in LPS-treated cells, β-Catenin expression and the effect of SFRP4 on neuronal cells in SCI were detected. Finally, the effectiveness of the miR-137/KDM4A/SFRP4/Wnt/β-Catenin axis was verified in vivo.

RESULTS

KDM4A was abnormally elevated in SCI. miR-137 targeted KDM4A. miR-137 effectively inhibited the apoptosis of LPS-challenged PC12 cells, which could be reversed after overexpressing KDM4A. KDM4A promoted SFRP4 expression through demethylation of H3K9me3. Overexpression of SFRP4 blocked the Wnt/β-Catenin pathway and promoted apoptosis of LPS-stimulated cells. In vivo, miR-137 overexpression remarkably improved SCI symptoms, accompanied by obviously increased β-Catenin expression and notably decreased KDM4A and SFRP4 expressions, while overexpressed KDM4A treatment showed the opposite trend in the presence of miR-137.

CONCLUSION

We demonstrated that miR-137 targeted KDM4A and then downregulated SFRP4 to ameliorate SCI in a Wnt/β-Catenin-dependent manner.

Overexpression of long non-coding RNA LINC00158 inhibits neuronal apoptosis by promoting autophagy in spinal cord injury

Spinal cord injury (SCI) is a common central nervous system disease. It is reported that long non-coding RNA LINC00158 is involved in the process of SCI. The purpose of this study was to explore the biological role of LINC00158 in the SCI. First, we established a rat SCI model by surgical method and evaluated the motor function of rats by the Basso-Beattie-Bresnahan locomotor rating scale. The results showed that the expression of LINC00158 decreased and apoptotic cells increased in the SCI model rats. Meanwhile, we found the upregulated LC3-II/LC3-I, Beclin-1, and p62 in the SCI rats. Then, primary rat spinal cord neurons were exposed to oxygen/glucose deprivation (OGD) as an in vitro cell model of SCI. After OGD treatment, the expression of LINC00158 decreased significantly and the apoptosis of spinal cord neurons increased. OGD treatment resulted in upregulation of LC3-II/LC3-I and Beclin-1 and downregulation of p62 in primary spinal cord neurons, which could be eliminated by overexpression of LINC00158. 3-Methyladenine and chloroquine (autophagy inhibitor) reversed the inhibitory effect of LINC00158 overexpression on apoptosis of primary spinal cord neurons. In conclusion, this study demonstrated that LINC00158 overexpression repressed neuronal apoptosis by promoting autophagy, suggesting that LINC00158 may be a potential therapeutic target in the SCI.

Neuroprotective effect of the Nrf2/ARE/miRNA145-5p signaling pathway in the early phase of spinal cord injury

AIMS

Spinal cord injury (SCI) is a debilitating neurological condition often associated with chronic neuroinflammation and redox imbalance. Oxidative stress is one of the main hallmark of secondary injury of SCI which is tightly regulated by nuclear factor E2-related factor 2/antioxidant response element (Nrf2/ARE) signaling. In this study, we aimed at investigating the interplay between inflammation-related miRNAs and the Nrf2 pathway in animal model of SCI.

MATERIALS AND METHODS

The expression of selected four validated miRNA-target pairs (miRNA223-3p, miRNA155-5p, miRNA145-5p, and miRNA124-3p) was examined at different time points (6 h, 12 h, 1 day, 3 day and 7 day) after SCI. Further, using GFAP-specific kelch-like ECH-associated protein 1 deletion (Keap1-/-) and whole-body Nrf2-/- knockout mice, we investigated the potential interplay between each miRNA and the Keap1/Nrf2 signaling system.

KEY FINDINGS

The expression of all miRNAs except miRNA155-5p significantly increased 24 h after SCI and decreased after 7 days. Interestingly, Keap1-/- mice only showed significant increase in the miRNA145-5p after 24 h SCI compared to the WT group. In addition, Keap1-/- mice showed significant decrease in CXCL10/12 (CXCL12 increased in Nrf2-/- mice), and TNF-α, and an increase in Mn-SOD and NQO-1 (Mn-SOD and NQO-1 decreased in Nrf2-/- mice) compared to WT mice.

SIGNIFICANCE

Our results suggest that astrocytic hyperactivation of Nrf2 exert neuroprotective effects at least in part through the upregulation of miRNA145-5p, a negative regulator of astrocyte proliferation, and induction of ARE in early phase of SCI. Further studies are needed to investigate the potential interplay between Nrf2 and miRNA145-5p in neuroinflammatory condition.

MicroRNA-137 inhibits the inflammatory response and extracellular matrix degradation in lipopolysaccharide-stimulated human nucleus pulposus cells by targeting activin a receptor type I

This study aimed to investigate the role played by microRNA (miR)-137 in intervertebral disc degeneration via targeting activin A receptor type I (ACVR1) and the underlying mechanism. Human nucleus pulposus cells were exposed to 10 ng/mL lipopolysaccharide (LPS) to establish an in vitro intervertebral disc degeneration model. ACVR1, extracellular matrix degradation-associated genes (aggrecan and collagen type II) and miR-137 levels were assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting assays. The MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) assay and flow cytometry were used to evaluate nucleus pulposus cell viability and apoptosis. Additionally, the association between miR-137 and ACVR1 was predicted and verified using bioinformatic software and dual-luciferase reporter assays. Furthermore, the secretion of inflammatory factors was analyzed via enzyme linked immunosorbent assay (ELISA). Our results confirmed that ACVR1 was upregulated in lipopolysaccharide-treated nucleus pulposus cells. Lipopolysaccharide suppressed cell viability, promoted apoptosis, enhanced the secretion of inflammatory factors, and reduced aggrecan and collagen type II expression. However, these results were reversed upon ACVR1 silencing. Our data revealed that ACVR1 directly targets miR-137 and is negatively regulated by miR-137 in nucleus pulposus cells. Additionally, the miR-137 mimic promoted cell growth, reduced cell apoptosis, reduced the secretion of inflammatory cytokines, and accelerated extracellular matrix accumulation in lipopolysaccharide-exposed nucleus pulposus cells. However, ACVR1 plasmid abolished the functions of the miR-137 mimic in lipopolysaccharide-exposed nucleus pulposus cells. Together, these findings indicate that miR-137 suppresses the inflammatory response and extracellular matrix degradation in lipopolysaccharide-treated nucleus pulposus cells by targeting ACVR1.

Resveratrol promotes axonal regeneration after spinal cord injury through activating Wnt/β-catenin signaling pathway

Background: Spinal cord injury (SCI) is characterized by autonomic dysreflexia, chronic pain, sensory and motor deficits. Resveratrol has shown potential neuroprotective function in several neurodegenerative diseases’ models. However, if resveratrol could improve the function recovery after SCI and the further mechanism have not been investigated.

Methods: SCI rat model was established through laminectomy at lamina T9-10 aseptically. Basso, beattie and bresnahan (BBB) and inclined plane score, sensory recovery, spinal cord content, and inflammatory factors were measured. The levels of GAP43, NF421, GFAP, Bax, Bcl-2 and caspase-3 were measured using immunohistochemical staining. Tunel staining was applied to detect apoptosis level.

Results: Resveratrol significantly improved the function recovery, promoted axonal regeneration, suppressed apoptosis after SCI. The activation of Wnt/β-catenin signaling pathway was achieved by resveratrol. XAV939 significantly reversed the influence of resveratrol on function recovery, axonal regeneration, apoptosis after SCI.

Conclusions: Resveratrol could promote the function recovery and axonal regeneration, improve histological damage, inhibit apoptosis level after SCI through regulating Wnt/β-catenin signaling pathway. This research expanded the regulatory mechanism of resveratrol in SCI injury.

MicroRNA-137-3p Protects PC12 Cells Against Oxidative Stress by Downregulation of Calpain-2 and nNOS

The imbalance between excess reactive oxygen species (ROS) generation and insufficient antioxidant defenses contribute to a range of neurodegenerative diseases. High ROS levels damage cellular macromolecules such as DNA, proteins and lipids, leading to neuron vulnerability and eventual death. However, the underlying molecular mechanism of the ROS regulation is not fully elucidated. Recently, an increasing number of studies suggest that microRNAs (miRNAs) emerge as the targets in regulating oxidative stress. We recently reported the neuroprotective effect of miR-137-3p for brachial plexus avulsion-induced motoneuron death. The present study is sought to investigate whether miR-137-3p also could protect PC12 cells against hydrogen peroxide (H2O2) induced neurotoxicity. By using cell viability assay, ROS assay, gene and protein expression assay, we found that PC-12 cells exposed to H2O2 exhibited decreased cell viability, increased expression levels of calpain-2 and neuronal nitric oxide synthase (nNOS), whereas a decreased miR-137-3p expression. Importantly, restoring the miR-137-3p levels in H2O2 exposure robustly inhibited the elevated nNOS, calpain-2 and ROS expression levels, which subsequently improved the cell viability. Furthermore, the suppressive effect of miR-137-3p on the elevated ROS level under oxidative stress was considerably blunted when we mutated the binding site of calpain-2 targted by miR-137-3p, suggesting the critical role of calpain-2 involving the neuroprotective effect of miR-137-3p. Collectively, these findings highlight the neuroprotective role of miR-137-3p through down-regulating calpain and NOS activity, suggesting its potential role for combating oxidative stress insults in the neurodegenerative diseases.

Plasma miR-370-3P as a Biomarker of Sepsis-Associated Encephalopathy, the Transcriptomic Profiling Analysis of Microrna-Arrays From Mouse Brains

The diagnosis of sepsis-associated encephalopathy (SAE), an alteration of conscious from sepsis, is difficult due to the similarity to altered states of conscious that occur from other causes. Transcriptomic analyses between mouse brains at 24 h after cecal ligation and puncture (CLP) (SAE brain as evaluated by SHIRPA score) and at 120 h post-CLP (survivor) were performed to discover the SAE biomarker. Then, candidate microRNAs were validated in mouse and patient samples.As such, increased miR-370-3p in SAE mouse-brains (compared with recovery phase) was demonstrated by transcriptomic miR-profiling and was highly expressed in brain (but not other organs) of 24 h post-CLP mice. Plasma miR-370-3p also increased in CLP but was non-detectable in bilateral-nephrectomy (BiNx, a representative model of acute uremic encephalopathy) despite blood brain barrier permeability defect (determined by plasma s100β and Evan blue dye assay) in both conditions. In parallel, high plasma miR-370-3p was demonstrated in patients with SAE (but not sepsis alone or uremia) suggesting the specificity toward SAE. The association among TNF-α, miR-370-3p and brain apoptosis was demonstrated by high serum TNF-α and increased brain apoptosis in SAE mice, TNF-α (but not other cytokines) activated miR-370-3p expression in PC-12 neuron cell, and increased cell apoptosis in miR-370-3p transfected PC-12 after incubation with TNF-α.In conclusion, miR-370-3p increased in brain and plasma of SAE mice but not uremic encephalopathy. Perhaps, TNF-α enhances cell susceptibility toward brain apoptosis in SAE, in part, through miR-370-3p induction in neuron. Our pilot results in patients with SAE supported the possibility that plasma miR-370-3p is an interesting SAE biomarker candidate. Further studies are warranted.

Silencing of Long Noncoding RNA Growth Arrest-Specific 5 Alleviates Neuronal Cell Apoptosis and Inflammatory Responses Through Sponging microRNA-93 to Repress PTEN Expression in Spinal Cord Injury

A secondary injury induced by a spinal cord injury (SCI) remains the main cause of devastating neural dysfunction; therefore, it has been the subject of focused research for many years. Long noncoding RNA (lncRNA) has been found to participate in the SCI process, and this finding presents a high potential for diagnosis and treatment; however, the role of lncRNA in a secondary injury induced by SCI remains unclear. The aim of this study was to investigate the regulatory effect of lncRNA growth arrest–specific transcript 5 (GAS5) in secondary injury during SCI. The SCI mice model and hypoxic cellular model were established to research the roles of lncRNA GAS5 during SCI. Reverse transcription quantitative polymerase chain reaction (qRT-PCR) was conducted to determine the expression levels of microR-93 (miR-93) and lncRNA GAS5. Western blot analysis of the apoptosis regulator protein and terminal deoxynucleotidyl transferase dUTP nick end labeling assay was conducted to evaluate neuron cell apoptosis. Basso, Beattie, and Bresnahan (BBB) scores were calculated to assess neurological function. Flow cytometry was used to determine neuron cell apoptosis. The associations among GAS5, miR-93, and the phosphatase and tensin homolog (PTEN) were disclosed using RNA immunoprecipitation (RIP) assay, RNA pulldown assay, and dual-luciferase reporter assay. QRT-PCR demonstrated that GAS5 was significantly upregulated in both the SCI mice and hypoxic cellular models. GAS5 knockdown suppressed neuron cell apoptosis and inflammatory response in the SCI mice model. Further studies have indicated that GAS5 functions as a competing endogenous RNA (ceRNA) by sponging miR-93 in neuronal cells. In addition, PTEN was a target of miR-93, and GAS5 knockdown exhibited its anti-apoptotic and anti-inflammatory effects through the miR-93/PTEN axis. These findings suggest that the GAS5/miR-93/PTEN axis may be a promising therapeutic target for SCI.

Mesenchymal stem cell-derived exosomes containing miR-145-5p reduce inflammation in spinal cord injury by regulating the TLR4/NF-κB signaling pathway

EXs (Exosomes) secreted by mesenchymal stem cells (MSCs) have the potential to treat spinal cord injury (SCI), this study aimed to further explore the therapeutic effect of EXs on SCI. Firstly, EXs were extracted from MSCs and analyzed with a transmission electron microscope. Next, MSCs with or without the miR-145-5p plasmid were injected into the SCI rat model, and then rat damage was evaluated by BBB score, HE staining and Nissl staining. And then Luciferase experiment verified the targeting relationship between miR-145-5p and TLR4. Furthermore, LPS-induced PC12 cells were established and incubated with Dil-labeled MSC-EXs to explore their effects on cell viability, apoptosis and inflammation through MTT, flow cytometry and ELISA, respectively. In addition, expressions of TLR4/NF-κB signaling pathway related factors were measured by qRT-PCR and Western blot. The results showed that after MSCs were successfully isolated, the existence of EXs in MSCs was confirmed. Moreover, MSC-EXs containing miR-145-5p improved functional recovery and reduced histopathological injury and inflammation in SCI rats. And MSC-EXs promoted miR-145-5p expression in spinal cord tissue and inhibited TLR4/NF-κB pathway activation in SCI rats. MSC-EXs inhibited LPS-induced inflammatory response and activation of the TLR4/NF-κB pathway in PC12 cells. In addition, we also found that miR-145-5p specifically targeted TLR4. TLR4 overexpression significantly reversed the effect of EX-miR-145-5p on maintaining PC12 cell viability, inhibiting apoptosis and inflammatory response, and activating TLR4/NF- κB pathway. In conclusion, mesenchymal stem cell-derived EXs containing miR-145-5p reduce inflammation in spinal cord injury by regulating the TLR4/NF-κB signaling pathway.

MiR-137 promotes cell growth and inhibits extracellular matrix protein expression in H2O2-induced human trabecular meshwork cells by targeting Src

Glaucoma is a progressive optic neuropathy in more than 25 % of cases in patients with permanent blindness. The microRNA is implicated in modulating the cellular function of the trabecular meshwork (TM). The aim of this study is to investigate the role of miR-137 in glaucoma and illustrate the potential molecular mechanisms. We show that miR-137 was down-regulated in H₂O₂-induced human trabecular meshwork cells (HTMCs), and overexpression of miR-137 attenuated H₂O₂-induced cell growth inhibition, apoptosis and elevated extracellular matrix (ECM) protein expression. In addition, miR-137 blocked the activation of YAP/TAZ by directly targeting src. Overexpression of src or activation of the YAP/TAZ pathway partly abrogated the effects of miR-137 on H₂O₂-induced cell viability and apoptosis and dampened the inhibition effect on ECM protein expression. In conclusion, miR-137 promotes cell growth and inhibits extracellular matrix protein expression in H₂O₂-induced human trabecular meshwork cells via the YAP/TAZ pathway by targeting src. Hence, miR-137 might be used as a novel therapeutic target to treat glaucoma.

MicroRNA-92a-3p enhances functional recovery and suppresses apoptosis after spinal cord injury via targeting phosphatase and tensin homolog

Spinal cord injury (SCI) is a neurological disease commonly caused by traumatic events on spinal cords. MiRNA-92a-3p is reported to be down-regulated after SCI. Our study investigated the effects of up-regulated miR-92a-3p on SCI and the underlying mechanisms. SCI mice model was established to evaluate the functional recovery of hindlimbs of mice through open-field locomotion and scored by Basso, Beattie, and Bresnahan (BBB) locomotion scale. Apoptosis of spinal cord cells was determined by flow cytometry. The effects of miR-92a-3p on SCI were detected by intrathecally injecting miR-92a-3p agomiR (agomiR-92) into the mice prior to the establishment of SCI. Phosphatase and tensin homolog (PTEN) was predicted as a target of miR-29a-3p by TargetScan. We further assessed the effects of agomiR-92 or/and overexpressed PTEN on apoptosis rates and apoptotic protein expressions in SCI mice. Moreover, the activation of protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling was determined by Western blot. The results showed that compared with the sham-operated mice, SCI mice had much lower BBB scores, and theapoptosis rate of spinal cord cells was significantly increased. After SCI, the expression of miR-92a-3p was down-regulated, and increased expression of miR-92a-3p induced by agomiR-92 further significantly increased the BBB score and decreased apoptosis. PTEN was specifically targeted by miR-92a-3p. In addition, the phosphorylation levels of Akt and mTOR were up-regulated under the treatment of agomiR-92. Our data demonstrated that the neuroprotective effects of miR-92a-3p on spinal cord safter SCI were highly associated with the activation of the PTEN/AKT/mTOR pathway.

miR-495 reduces neuronal cell apoptosis and relieves acute spinal cord injury through inhibiting PRDM5

This study aims to investigate the role of miR-495 in neuronal cell apoptosis after acute spinal cord injury (ASCI). The ASCI rat model was established and the Basso, Beattie, and Bresnahan (BBB) score was assessed. miR-495, PR domain containing 5 (PRDM5), and Bcl-2 expressions were measured by qRT-PCR or western blotting. Neuronal cell line PC-12 was subjected to hypoxia condition to simulate the in vitro ASCI model. PC-12 cell apoptosis was measured by flow cytometry, and the interaction between miR-495 and PRDM5 was confirmed by dual luciferase reporter assay. Results showed that BBB score was significantly decreased in ASCI rats compared with sham rats. miR-495 expression was down-regulated in spinal cord tissue of ASCI rats and hypoxia-induced PC-12 cells, and PRDM5 protein level was up-regulated in spinal cord tissue of ASCI rats and hypoxia-induced PC-12 cells. miR-495 overexpression could reduce apoptosis of PC-12 cells, and up-regulated anti-apoptosis protein Bcl-2 protein level. Moreover, PRDM5 was a target of miR-495, and mRNA and protein levels of PRDM5 were negatively regulated by miR-495. miR-495 overexpression could reduce the hypoxia-induced PC-12 cell apoptosis, while PRDM5 overexpression abolished this inhibiting effect. The agomir-495 was injected into ASCI rats, and Bcl-2 protein level and BBB score were increased, but the PRDM5 overexpression reversed these results. Overall, we concluded that miR-495 could inhibit neuronal cell apoptosis and relieve acute spinal cord injury through inhibiting PRDM5.

Programmed cell death in spinal cord injury pathogenesis and therapy

Spinal cord injury (SCI) always leads to functional deterioration due to a series of processes including cell death. In recent years, programmed cell death (PCD) is considered to be a critical process after SCI, and various forms of PCD were discovered in recent years, including apoptosis, necroptosis, autophagy, ferroptosis, pyroptosis and paraptosis. Unlike necrosis, PCD is known as an active cell death mediated by a cascade of gene expression events, and it is crucial for elimination unnecessary and damaged cells, as well as a defence mechanism. Therefore, it would be meaningful to characterize the roles of PCD to not only enhance our understanding of the pathophysiological processes, but also improve functional recovery after SCI. This review will summarize and explore the most recent advances on how apoptosis, necroptosis, autophagy, ferroptosis, pyroptosis and paraptosis are involved in SCI. This review can help us to understand the various functions of PCD in the pathological processes of SCI, and contribute to our novel understanding of SCI of unknown aetiology in the near future.

FBW7 protects against spinal cord injury by mitigating inflammation-associated neuronal apoptosis in mice

Spinal cord injury (SCI) leads to severe and long-lasting neurological disability. Presently, the lack of effective therapies for SCI is largely attributable to an incomplete understanding of its pathogenesis. F-box and WD repeat domain-containing protein 7 (FBW7, also known as FBXW7) is a type of E3 ubiquitin ligase complex, and plays essential roles in regulating different pathological and physiological processes. In this study, we attempted to explore the effects of FBW7 on SCI progression by the in vivo and in vitro experiments. SCI mice showed significantly reduced expression of FBW7 in spinal cord tissues. Promoting FBW7 expression via intrathecal injection of AAV9/FBW7 effectively improved locomotor function in SCI mice. Neuronal death in spinal cords of SCI mice was obviously ameliorated by FBW7 over-expression, along with greatly decreased expression of cleaved Caspase-3. In addition, microglial activation in spinal cord specimens was detected in SCI mice through increasing Iba-1 expression levels, which was, however, attenuated in SCI mice injected with AAV9/FBW7. Additionally, FBW7 over-expression dramatically restrained inflammatory response in spinal cord tissues of SCI mice, as evidenced by the down-regulated expression of tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) through blocking the activation of nuclear factor-κB (NF-κB) signaling. These anti-inflammatory effects of FBW7 were confirmed in LPS-stimulated mouse microglial BV2 cells. Finally, our in vitro studies showed that conditional medium (CM) collected from LPS-incubated BV2 cells markedly induced apoptosis in the isolated primary spinal neurons; However, this effect was overtly ameliorated by CM from LPS-exposed BV2 cells over-expressing FBW7. Thus, FBW7-regulated inflammation in microglial cells was involved in the amelioration of neuronal apoptosis during SCI development. Collectively, these findings illustrated that FBW7 expression was down-regulated in spinal cords of SCI mice, and promoting its expression could effectively mitigate SCI progression by repressing microglial inflammation and neuronal death.

EGCG treats ICH via up-regulating miR-137-3p and inhibiting Parthanatos

Intracranial hemorrhage (ICH) causes high mortality and disability without effective treatment in the clinical setting. (-)-Epigallocatechin-3-gallate (EGCG) exerts an essential role in the central nervous system and offers a promising therapeutic agent for the treatment of oxidative damage-related diseases. MiR-137 can inhibit the oxidative stress and apoptosis to attenuate neuronal injury. However, the role of EGCG in regulating miR-137-3p and neuronal Parthanatos remains to be unclear. In the present study, we build the ICH mice model to investigate the antioxidant effects of EGCG via upregulating miR-137-3p and inhibiting neuronal Parthanatos. We revealed that EGCG upregulated miR-137-3p and inhibited neuronal Parthanatos, and promoted the functional recovery, alleviated ICH-induced brain injury, and reduced oxidative stress in mice following ICH. However, following the inhibition of miR-137-3p and activation of Parthanatos, EGCG was unable to exert neuroprotective roles. These combined results suggest that EGCG may upregulate miR-137-3p and inhibit neuronal Parthanatos to accelerate functional recovery in mice after ICH, laying the foundation for EGCG to be a novel strategy for the treatment of neuronal injuries related to Parthanatos.

Comprehensive analysis of the differential expression profile of microRNAs in rats with spinal cord injury treated by electroacupuncture

Abnormal microRNA (miRNA) expression has been implicated in spinal cord injury (SCI), but the underlying mechanisms are poorly understood. To observe the effect of electroacupuncture (EA) on miRNA expression profiles in SCI rats and investigate the potential mechanisms involved in this process, Sprague-Dawley rats were divided into sham, SCI and SCI+EA groups (n=6 each). Basso, Beattie and Bresnahan (BBB) scoring and hematoxylin-eosin staining of cortical tissues were used to evaluate spinal cord recovery with EA treatment 21 days post-surgery across the three groups. To investigate miRNA expression profiles, 6 Sprague-Dawley rats were randomly divided into SCI and SCI+EA groups (n=3 in each group) and examined using next-generation sequencing. Integrated miRNA-mRNA-pathway network analysis was performed to elucidate the interaction network of the candidate miRNAs, their target genes and the involved pathways. Behavioral scores suggested that hindlimb motor functions improved with EA treatments. Apoptotic indices were lower in the SCI+EA group compared with the SCI group. It was also observed that 168 miRNAs were differentially expressed between the SCI and SCI+EA groups, with 29 upregulated and 139 downregulated miRNAs in the SCI+EA group. Changes in miRNA expression are involved in SCI physiopathology, including inflammation and apoptosis. Reverse transcription-quantitative PCR measurement of the five candidate miRNAs, namely rno-miR-219a-5p, rno-miR-486, rno-miR-136-5p, rno-miR-128-3p, and rno-miR-7b, was consistent with RNA sequencing data. Integrated miRNA-mRNA-pathway analysis suggested that the MAPK, Wnt and NF-κB signaling pathways were involved in EA-mediated recovery from SCI. The present study evaluated the miRNA expression profiles involved in EA-treated SCI rats and demonstrated the potential mechanism and functional role of miRNAs in SCI in rats.

Insulin-like growth factor-1 enhances neuroprotective effects of neural stem cell exosomes after spinal cord injury via an miR-219a-2-3p/YY1 mechanism

Spinal cord injury (SCI) remains the most common cause of paralysis, and there are no effective therapies for SCI patients. Neural stem cell (NSC)-derived exosomes can attenuate apoptosis and neuroinflammation after traumatic spinal cord injury, but the mechanisms underlying these effects remain unclear. Here, we examined the efficacy of miRNAs isolated from exosomes as treatments for SCI and characterized their mechanisms of action. Furthermore, we evaluated the effects of exosomes formed in the presence of insulin growth factor-1 (IFG-1, IGF-Exo), which promotes neural proliferation and regeneration, as well as normal exosomes (Nor-Exo) and compared control and H₂O₂-treated groups both in vitro and in vivo. Using microRNA sequencing and qRT-PCR, we identified miR-219a-2-3p, levels of which were higher in the IGF-Exo than Nor-Exo group and played crucial anti-inflammatory and anti-apoptosis roles. Additional experiments revealed that IGF-Exo inhibits YY1 expression through up-regulation of miR-219a-2-3p. This in turn inhibits the NF-κB pathway, partly inhibiting neuroinflammation and promoting the neuroprotective effects after SCI.

Protective Effects of MiR-129-5p on Acute Spinal Cord Injury Rats

BACKGROUND Spinal cord injury (SCI) is a severe devastating condition associated with serious disability and neurologic deficits. Aberrant micro RNA (miRNA) expression has been related to a variety of central nervous system diseases including SCI. In the present study, we aimed to discover the role of miR-129-5p on SCI. MATERIAL AND METHODS An acute SCI rat model was induced, following the modified Allen method. A total of 36 rats were randomly assigned into 4 groups (n=9 in every group): Sham group; Model group (SCI+saline); SCI+NC group; and SCI+miR-129-5p group (100 nm solution, every 2 days). Basso-Beattie-Bresnahan (BBB) locomotor rating score was carried out to determine functional recovery. TUNEL (terminal dUTP nick-end labeling) staining was used to evaluate cell apoptosis. Hematoxylin and eosin staining was performed to assess the pathological state of spinal cord. Furthermore, western blot assay was conducted to measure the calpain1 and calpain2 expression. RESULTS Our data suggested that the expression level of miR-129-5p was markedly reduced in rats after SCI. Then miR-129-5p mimic was injected into the vertebral canal. We found that the SCI+miR-129-5p group had a high score in the BBB test compared with the SCI+NC group and the Model group. The overexpression of miR-129-5p obviously reduced tissue loss, damaged cells, and the number of TUNEL positive cells. Moreover, western blot assay exhibited that overexpression of miR-129-5p decreased calpain1, calpain2, and cleaved caspase-3 expression. CONCLUSIONS Our findings suggested that overexpression of miR-129-5p improved neurological function by promoting functional recovery, reducing tissue loss and cell apoptosis in rats in an SCI model, possibly through downregulation of calpain1 and calpain2.

miR-155-5p Promotes Dorsal Root Ganglion Neuron Axonal Growth in an Inhibitory Microenvironment via the cAMP/PKA Pathway

Sensory dysfunction post spinal cord injury causes patients great distress. Sciatic nerve conditioning injury (SNCI) has been shown to restore sensory function after spinal cord dorsal column injury (SDCL); however, the underlying mechanism of this recovery remains unclear. We performed a microarray assay to determine the associated miRNAs that might regulate the process of SNCI promoting SDCL repair. In total, 13 miRNAs were identified according to our inclusion criteria, and RT-qPCR was used to verify the microarray results. Among the 13 miRNAs, the miR-155-5p levels were decreased at 9 h, 3 d, 7 d, 14 d, 28 d, 2 m and 3 m timepoints in the SDCL group, while the SNCI group had a smaller decrease. Thus, miR-155-5p was chosen for further study after a literature review and an analysis with the TargetScan online tool. Specifically, miR-155-5p targets PKI-α, and the expression pattern of PKI-α was opposite that of miR-155-5p in both the SDCL and SNCI groups. Interestingly, miR-155-5p could promote dorsal root ganglion (DRG) neuron axon growth via the cAMP/PKA pathway and in a TNF-α, IL-1β or MAG inhibitory microenvironment in vitro. Furthermore, miR-155-5p could regulate the cAMP/PKA pathway and promote sensory conduction function recovery post dorsal column injury as detected by NF-200 immunohistochemistry, somatosensory-evoked potentials, BBB scale and tape removal test. Collectively, our results demonstrated that miR-155-5p participates in the molecular mechanism by which SNCI promotes the repair of SDCL and that upregulated miR-155-5p can repair SDCL by enhancing DRG neuron axon growth via the cAMP/PKA pathway. These findings suggest a novel treatment target for spinal cord injury.

MicroRNAs in contusion spinal cord injury: pathophysiology and clinical utility

Spinal cord injury (SCI) in humans is a common central nervous system trauma. Pathophysiologically, SCI involves both primary and secondary damages. Therapeutically, targeting secondary damage including inflammation, neuropathic pain, apoptosis, demyelination, and glial reaction to promote functional benefits for SCI patients has long been considered a potential treatment strategy by neuroscientists and clinicians. As a type of small non-coding RNA, microRNAs (miRNAs) have been shown to play essential roles in the regulation of pathophysiologic processes of SCI and are considered to be an effective treatment method for SCI. Dysregulated expression of miRNAs is observed in SCI patients and animal models of SCI. Furthermore, miRNAs might also be used as biomarkers for diagnostic and prognostic purposes in SCI. Given contusion injury is the most clinically relevant type of SCI, this review mainly focuses on the role of miRNAs in the pathophysiology of contusion SCI and the putative utilization of miRNAs as diagnostic biomarkers and therapeutic targets for contusion SCI.

Neurotoxicological effects induced by up-regulation of miR-137 following triclosan exposure to zebrafish (Danio rerio)

Triclosan (TCS) is a prevalent anthropogenic contaminant in aquatic environments and its chronic exposure can lead to a series of neurotoxic effects in zebrafish. Both qRT-PCR and W-ISH identified that TCS exposure resulted in significant up-regulation of miR-137, but downregulation of its regulatory genes (bcl11aa, MAPK6 and Runx1). These target genes are mainly associated with neurodevelopment and the MAPK signaling pathway, and showed especially high expression in the brain. After overexpression or knockdown treatments by manual intervention of miR-137, a series of abnormalities were induced, such as ventricular abnormality, bent spine, yolk cyst, closure of swim sac and venous sinus hemorrhage. The most sensitive larval toxicological endpoint from intervened miR-137 expression was impairment of the central nervous system (CNS), ventricular abnormalities and notochord curvature. Microinjection of microRNA mimics or inhibitors of miR-137 both caused zebrafish malformations. The posterior lateral line neuromasts became obscured and decreased in number in intervened miR-137 groups and TCS-exposure groups. Up-regulation of miR-137 led to more severe neurotoxic effects than its down-regulation. Behavioral observations demonstrated that both TCS exposure and miR-137 over-expression led to inhibited hearing or vision sensitivity. HE staining indicated that hearing and vision abnormalities induced by long-term TCS exposure originated from CNS injury, such as reduced glial cells and loose and hollow fiber structures. The findings of this study enhance our mechanistic understanding of neurotoxicity in aquatic animals in response to TCS exposure. These observations provide theoretical guidance for development of early intervention treatments for nervous system diseases.

Curcumin alleviates LPS-induced inflammation and oxidative stress in mouse microglial BV2 cells by targeting miR-137-3p/NeuroD1

Curcumin has been reported to exert protective effects on inflammation-related diseases, including spinal cord injury (SCI).

MiR-20a Plays a Key Regulatory Role in the Repair of Spinal Cord Dorsal Column Lesion via PDZ-RhoGEF/RhoA/GAP43 Axis in Rat

Spinal cord injury (SCI) causes sensory dysfunctions such as paresthesia, dysesthesia, and chronic neuropathic pain. MiR-20a facilitates the axonal outgrowth of the cortical neurons. However, the role of miR-20a in the axonal outgrowth of primary sensory neurons and spinal cord dorsal column lesion (SDCL) is yet unknown. Therefore, the role of miR-20a post-SDCL was investigated in rat. The NF-200 immunofluorescence staining was applied to observe whether axonal outgrowth of dorsal root ganglion (DRG) neurons could be altered by miR-20a or PDZ-RhoGEF modulation in vitro. The expression of miR-20a was quantized with RT-PCR. Western blotting analyzed the expression of PDZ-RhoGEF/RhoA/GAP43 axis after miR-20a or PDZ-RhoGEF was modulated. The spinal cord sensory conduction function was assessed by somatosensory-evoked potentials and tape removal test. The results demonstrated that the expression of miR-20a decreased in a time-dependent manner post-SDCL. The regulation of miR-20a modulated the axonal growth and the expression of PDZ-RhoGEF/RhoA/GAP43 axis in vitro. The in vivo regulation of miR-20a altered the expression of miR-20a-PDZ-RhoGEF/RhoA/GAP43 axis and promoted the recovery of ascending sensory function post-SDCL. The results indicated that miR-20a/PDZ-RhoGEF/RhoA/GAP43 axis is associated with the pathophysiological process of SDCL. Thus, targeting the miR-20a/PDZ-RhoGEF /RhoA/GAP43 axis served as a novel strategy in promoting the sensory function recovery post-SCI.

Circulating microRNAs, Vascular Risk, and Physical Activity in Spinal Cord-Injured Subjects

The aim of this study was to compare the expression of serum microRNAs (miRNAs) in individuals with spinal cord injury (SCI) (athletes [SCI-A] and sedentary [SCI-S]) and able-bodied (AB) individuals, and investigate the relationship of miRNAs with carotid intima-media thickness (cIMT) and serum oxidized LDL-cholesterol (oxLDL) among SCI subjects. Seventeen SCI-S, 23 SCI-A, and 22 AB males were evaluated by clinical and laboratory analysis, and had oxLDL and cIMT measured by enzyme-linked immunosorbent assay (ELISA) and ultrasonography, respectively. A total of 754 miRNAs were measured using a TaqMan OpenArray^® Human MicroRNA system. SCI-S subjects had higher cIMT and oxLDL than SCI-A and AB. Compared with AB, only one miRNA was differently expressed in both SCI-A and SCI-S individuals, whereas 25 miRNAs were differently expressed in SCI-S, but not in SCI-A. Of these 25 miRNAs, 22 showed different expression between SCI-S and SCI-A. Several miRNAs correlated with oxLDL and cIMT among all SCI individuals. Notably, miR-125b-5p, miR-146a-5p, miR-328-3p, miR-191-5p, miR-103a-3p, and miR-30b-5p correlated with both oxLDL and cIMT, and showed distinct expression between the SCI-A and SCI-S groups. Gene set enrichment analysis demonstrated that miRNAs related to cIMT and oxLDL may be involved in molecular pathways regulating vascular function and remodeling. In conclusion, this exploratory analysis suggests that variations in circulating miRNA expression in individuals with SCI compared with AB subjects are markedly attenuated by regular physical activity. Several miRNAs may be involved in physical activity-related improvements in vascular risk and remodeling among SCI individuals.

Hippocampal TET1 and TET2 Expression and DNA Hydroxymethylation Are Affected by Physical Exercise in Aged Mice

The function of 5-hydroxymethylcytosine (5hmC) is poorly understood. 5hmC is an epigenetic modification of DNA, resulting from the oxidation of 5-methylcytosine (5mC) by the Fe2⁺, and 2-oxoglutarate-dependent, 10–11 translocation methylcytosine dioxygenases (TET1, TET2, and TET3). Recent evidence suggests that, in addition to being an intermediate in active demethylation, 5hmC may also have an epigenetic role. 5hmC is enriched in the adult brain, where it has been implicated in regulating neurogenesis. The rate of adult neurogenesis decreases with age, however physical exercise has been shown to counteract this deficit. Here, we investigated the impact of voluntary exercise on the age-related changes of TET1, TET2, expression and 5hmC content in the hippocampus and hypothalamus. For this purpose, we used voluntary exercise in young adult (3 months) and aged (18 months) mice as a rodent model of healthy brain aging. We measured the levels of hippocampal and hypothalamic TET1, TET2 mRNA, and 5hmC and memory [Object Location (OL) test] in mice that either exercised for 1 month or remained sedentary. While aging was associated with decreased TET1 and TET2 expression, voluntary exercise counteracted the decline in expression. Moreover, aged mice that exercised had higher hippocampal 5hmC content in the promoter region of miR-137, an miRNA involved in adult neurogenesis. Exercise improved memory in aged mice, and there was a positive correlation between 5hmC miR-137 levels and performance in the OL test. In the hypothalamus neither exercise nor aging affected TET1 or TET2 expression. These results suggest that exercise partially restores the age-related decrease in hippocampal TET1 and TET2 expression, which may be linked to the improvement in memory. Future studies should further determine the specific genes where changes in 5hmC levels may mediate the exercise-induced improvements in memory and neurogenesis in aged animals.

Identification of Dysregulated microRNA Networks in Schwann Cell-Like Cultures Exposed to Immune Challenge: Potential Crosstalk with the Protective VIP/PACAP Neuropeptide System

Following peripheral nerve injury, dysregulations of certain non-coding microRNAs (miRNAs) occur in Schwann cells. Whether these alterations are the result of local inflammation and/or correlate with perturbations in the expression profile of the protective vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase-activating polypeptide (PACAP) system is currently unknown. To address these issues, we aimed at profiling the expression of selected miRNAs in the rat RT4 Schwann cell line. Cells exposed to lipopolysaccharide (LPS), to mimic the local inflammatory milieu, were appraised by real-time qPCR, Western blot and ELISAs. We found that upon LPS treatment, levels of pro-inflammatory cytokines (IL-1β, -6, -18, -17A, MCP-1 and TNFα) increased in a time-dependent manner. Unexpectedly, the expression levels of VIP and PACAP were also increased. Conversely, levels of VPAC1 and VPAC2 receptors were reduced. Downregulated miRNAs included miR-181b, -145, -27a, -340 and -132 whereas upregulated ones were miR-21, -206, -146a, -34a, -155, -204 and -29a, respectively. Regression analyses revealed that a subset of the identified miRNAs inversely correlated with the expression of VPAC1 and VPAC2 receptors. In conclusion, these findings identified a novel subset of miRNAs that are dysregulated by immune challenge whose activities might elicit a regulatory function on the VIP/PACAP system.