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

Microglia: a promising therapeutic target in spinal cord injury

Microglia are present throughout the central nervous system and are vital in neural repair, nutrition, phagocytosis, immunological regulation, and maintaining neuronal function. In a healthy spinal cord, microglia are accountable for immune surveillance, however, when a spinal cord injury occurs, the microenvironment drastically changes, leading to glial scars and failed axonal regeneration. In this context, microglia vary their gene and protein expression during activation, and proliferation in reaction to the injury, influencing injury responses both favorably and unfavorably. A dynamic and multifaceted injury response is mediated by microglia, which interact directly with neurons, astrocytes, oligodendrocytes, and neural stem/progenitor cells. Despite a clear understanding of their essential nature and origin, the mechanisms of action and new functions of microglia in spinal cord injury require extensive research. This review summarizes current studies on microglial genesis, physiological function, and pathological state, highlights their crucial roles in spinal cord injury, and proposes microglia as a therapeutic target.

Systemic administration of blood-derived exosomes induced by remote ischemic post-conditioning, by delivering a specific cluster of miRNAs, ameliorates ischemic damage and neurological function

MicroRNAs, contained in exosomes or freely circulating in the plasma, might play a pivotal role in the infarct-sparing effect exerted by remote limb ischemic postconditioning (RLIP). The aims of the present study were: (1) To evaluate the effect of pure exosomes isolated from plasma of animals subjected to RLIP systemically administered to ischemic rats; (2) To finely dissect exosomes content in terms of miRNAs; (3) To select those regulatory miRNAs specifically expressed in protective exosomes and to identify molecular pathways involved in their neurobeneficial effects. Circulating exosomes were isolated from blood of animals exposed to RLIP and administered to animals exposed to tMCAO by intracerebroventricular, intraperitoneal or intranasal routes. Exosomal miRNA signature was evaluated by microarray and FISH analysis. Plasmatic exosomes isolated from plasma of RLIP rats attenuated cerebral ischemia reperfusion injury and improved neurological functions until 3 days after ischemia induction. Interestingly, miR-702-3p and miR-423-5p seem to be mainly involved in exosome protective action by modulating NOD1 and NLRP3, two key triggers of neuroinflammation and neuronal death. Collectively, the results of the present work demonstrated that plasma-released exosomes after RLIP may transfer a neuroprotective signal to the brain of ischemic animals, thus representing a potentially translatable therapeutic strategy in stroke.

Targeting NLRP3 Inflammasomes: A Trojan Horse Strategy for Intervention in Neurological Disorders

Recently, a growing focus has been on identifying critical mechanisms in neurological diseases that trigger a cascade of events, making it easier to target them effectively. One such mechanism is the inflammasome, an essential component of the immune response system that plays a crucial role in disease progression. The NLRP3 (nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3) inflammasome is a subcellular multiprotein complex that is widely expressed in the central nervous system (CNS) and can be activated by a variety of external and internal stimuli. When activated, the NLRP3 inflammasome triggers the production of proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18) and facilitates rapid cell death by assembling the inflammasome. These cytokines initiate inflammatory responses through various downstream signaling pathways, leading to damage to neurons. Therefore, the NLRP3 inflammasome is considered a significant contributor to the development of neuroinflammation. To counter the damage caused by NLRP3 inflammasome activation, researchers have investigated various interventions such as small molecules, antibodies, and cellular and gene therapy to regulate inflammasome activity. For instance, recent studies indicate that substances like micro-RNAs (e.g., miR-29c and mR-190) and drugs such as melatonin can reduce neuronal damage and suppress neuroinflammation through NLRP3. Furthermore, the transplantation of bone marrow mesenchymal stem cells resulted in a significant reduction in the levels of pyroptosis-related proteins NLRP3, caspase-1, IL-1β, and IL-18. However, it would benefit future research to have an in-depth review of the pharmacological and biological interventions targeting inflammasome activity. Therefore, our review of current evidence demonstrates that targeting NLRP3 inflammasomes could be a pivotal approach for intervention in neurological disorders.

Exosomes from hypoxic ADSCs ameliorate neuronal damage post spinal cord injury through circ-Wdfy3 delivery and inhibition of ferroptosis

BACKGROUND

Exosomes generated from adipose-derived mesenchymal stem cells (Exos), and in particular hypoxia-pretreated ADSCs (HExos), possess therapeutic properties that promote spinal cord repair following spinal cord injury (SCI). Nevertheless, the regulatory mechanisms through which HExos exert their effects remain unclear.

METHODS

Here, next-generation sequencing (NGS) was utilized to examine abnormal circRNA expression comparing HExos to Exos. Bioinformatics analysis and RNA pulldown assays together with luciferase reporter assays were applied to determine interactions among miRNAs, mRNAs and circRNAs. ELISA and immunofluorescence staining were used to examine inflammatory cytokine levels, apoptosis and ROS deposition in LPS-treated HT-22 cells, respectively. The therapeutic effects of Exos and HExos on a mouse model of SCI were analyzed by immunohistochemistry and immunofluorescence staining.

RESULTS

Our findings confirmed that HExos have more significant therapeutic influences on decreasing ROS and inflammatory cytokine levels post-SCI than Exos. NGS revealed that circ-Wdfy3 expression levels were significantly higher in HExos than Exos. Downregulation of circ-Wdfy3 led to a decrease in HExo-induced therapeutic effects on spinal cord repair post-SCI, indicating that circ-Wdfy3 has a critical role in the regulation of HExo-mediated protection against SCI. Our bioinformatics, RNA pulldown and luciferase reporter data demonstrated that GPX4 and miR-423-3p were downstream targets of circ-Wdfy3. GPX4 downregulation or miR-423-3p overexpression reversed the protective effects of circ-Wdfy3 on LPS-treated HT-22 cells. Furthermore, overexpression of circ-Wdfy3 led to an in increase in the Exo-induced therapeutic effects on spinal cord repair post-SCI through the inhibition of ferroptosis.

CONCLUSIONS

circ-WDfy3-overexpressing Exos promote spinal cord repair post-SCI through mediation of ferroptosis via the miR-138-5p/GPX4 pathway.

Curcumin-primed olfactory mucosa-derived mesenchymal stem cells mitigate cerebral ischemia/reperfusion injury-induced neuronal PANoptosis by modulating microglial polarization

BACKGROUND

Cerebral ischemia-reperfusion (I/R) injury often leads to neuronal death through persistent neuroinflammatory responses. Recent research has unveiled a unique inflammatory programmed cell death mode known as PANoptosis. However, direct evidence for PANoptosis in ischemic stroke-induced neuronal death has not been established. Although it is widely thought that modulating the balance of microglial phenotypic polarization in cerebral I/R could mitigate neuroinflammation-mediated neuronal death, it remains unknown whether microglial polarization influences PANoptotic neuronal death triggered by cerebral I/R. Our prior study demonstrated that curcumin (CUR) preconditioning could boost the neuroprotective properties of olfactory mucosa-derived mesenchymal stem cells (OM-MSCs) in intracerebral hemorrhage. Yet, the potential neuroprotective capacity of curcumin-pretreated OM-MSCs (CUR-OM-MSCs) on reducing PANoptotic neuronal death during cerebral I/R injury through modulating microglial polarization is uncertain.

METHODS

To mimic cerebral I/R injury, We established in vivo models of reversible middle cerebral artery occlusion (MCAO) in C57BL/6 mice and in vitro models of oxygen-glucose deprivation/reoxygenation (OGD/R) in HT22 neurons and BV2 microglia.

RESULTS

Our findings indicated that cerebral I/R injury caused PANoptotic neuronal death and triggered microglia to adopt an M1 (pro-inflammatory) phenotype both in vivo and in vitro. Curcumin pretreatment enhanced the proliferation and anti-inflammatory capacity of OM-MSCs. The CUR-OM-MSCs group experienced a more pronounced reduction in PANoptotic neuronal death and a better recovery of neurological function than the OM-MSCs group. Bioinformatic analysis revealed that microRNA-423-5p (miRNA-423-5p) expression was obviously upregulated in CUR-OM-MSCs compared to OM-MSCs. CUR-OM-MSCs treatment induced the switch to an M2 (anti-inflammatory) phenotype in microglia by releasing miRNA-423-5p, which targeted nucleotide-binding oligomerization domain 2 (NOD2), an upstream regulator of NF-kappaB (NF-κB) and Mitogen-Activated Protein Kinase (MAPK) signaling pathways, to attenuate PANoptotic neuronal death resulting from cerebral I/R.

CONCLUSION

This results provide the first demonstration of the existence of PANoptotic neuronal death in cerebral I/R conditions. Curcumin preconditioning enhanced the ameliorating effect of OM-MSCs on neuroinflammation mediated by microglia polarization via upregulating the abundance of miRNA-423-5p. This intervention effectively alleviates PANoptotic neuronal death resulting from cerebral I/R. The combination of curcumin with OM-MSCs holds promise as a potentially efficacious treatment for cerebral ischemic stroke in the future.

Evaluating the pro-survival potential of apoptotic bodies derived from 2D- and 3D- cultured adipose stem cells in ischaemic flaps

In the realm of large-area trauma flap transplantation, averting ischaemic necrosis emerges as a pivotal concern. Several key mechanisms, including the promotion of angiogenesis, the inhibition of oxidative stress, the suppression of cell death, and the mitigation of inflammation, are crucial for enhancing skin flap survival. Apoptotic bodies (ABs), arising from cell apoptosis, have recently emerged as significant contributors to these functions. This study engineered three-dimensional (3D)-ABs using tissue-like mouse adipose-derived stem cells (mADSCs) cultured in a 3D environment to compare their superior biological effects against 2D-ABs in bolstering skin flap survival. The findings reveal that 3D-ABs (85.74 ± 4.51) % outperform 2D-ABs (76.48 ± 5.04) % in enhancing the survival rate of ischaemic skin flaps (60.45 ± 8.95) % (all p < 0.05). Mechanistically, they stimulated angiogenesis, mitigated oxidative stress, suppressed apoptosis, and facilitated the transition of macrophages from M1 to M2 polarization (all p < 0.05). A comparative analysis of microRNA (miRNA) profiles in 3D- and 2D-ABs identified several specific miRNAs (miR-423-5p-up, miR30b-5p-down, etc.) with pertinent roles. In summary, ABs derived from mADSCs cultured in a 3D spheroid-like arrangement exhibit heightened biological activity compared to those from 2D-cultured mADSCs and are more effective in promoting ischaemic skin flap survival. These effects are attributed to their influence on specific miRNAs.

Understanding Propofol's Protective Mechanism in Tubular Epithelial Cells: Mitigating Pyroptosis via the miR-143-3p/ATPase Na + /K + Transporting Subunit Alpha 2 Pathway in Renal Ischemia-Reperfusion

Propofol (Pro), a prevalent intravenous anesthetic, has recently been recognized for its potential in mitigating ischemia-reperfusion (I/R) injuries. Despite a plethora of evidence suggesting the beneficial effects of low-dose Pro in renal I/R injury (RI/R), its role in modulating pyroptosis in renal tubular epithelial cells consequent to RI/R has not been thoroughly elucidated. In our investigation, we explored the therapeutic potential of Pro against pyroptosis in renal tubular epithelial cells under the duress of RI/R, employing both in vivo and in vitro models, while deciphering the intricate molecular pathways involved. Our results demonstrate an elevation in the expression of miR-143-3p, contrasted by a diminution in ATPase Na + /K + Transporting Subunit Alpha 2 (ATP1A2) under RI/R conditions. Pro effectively mitigates apoptosis in renal tubular epithelial cells induced by RI/R, principally characterized by the inhibition of pro-inflammatory cytokines interleukin (IL-)-1β and IL-18, enhancement of cellular viability, reduction in the ratio of pyroptotic cells, and suppression of nucleotide-binding domain and leucine-rich repeat-related family, pyrin domain containing 3 inflammasome activation along with the expression of cleaved caspase-1, and gasdermin D. Both knockdown and overexpression studies of miR-143-3p revealed its pivotal role in modulating RI/R-induced tubular cell pyroptosis. Notably, Pro's capacity to inhibit pyroptosis in renal tubular epithelial cells was found to be reversible following ATP1A2 knockdown. Furthermore, our study unveils miR-143-3p as a targeted regulator of ATP1A2 expression. From a mechanistic standpoint, Pro's therapeutic efficacy is attributed to its regulatory influence on miR-143-3p and ATP1A2 expression levels. In conclusion, our findings pioneer the understanding that Pro can significantly ameliorate pyroptosis in renal tubular epithelial cells in the context of RI/R, predominantly through the modulation of the miR-143-3p/ATP1A2 axis. This novel insight furnishes robust empirical support for the development of targeted therapeutics and clinical strategies in addressing RI/R.

New Insights on NLRP3 Inflammasome: Mechanisms of Activation, Inhibition, and Epigenetic Regulation

Inflammasomes are important modulators of inflammation. Dysregulation of inflammasomes can enhance vulnerability to conditions such as neurodegenerative diseases, autoinflammatory diseases, and metabolic disorders. Among various inflammasomes, Nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) is the best-characterized inflammasome related to inflammatory and neurodegenerative diseases. NLRP3 is an intracellular sensor that recognizes pathogen-associated molecular patterns and damage-associated patterns resulting in the assembly and activation of NLRP3 inflammasome. The NLRP3 inflammasome includes sensor NLRP3, adaptor apoptosis-associated speck-like protein (ASC), and effector cysteine protease procaspase-1 that plays an imperative role in caspase-1 stimulation which further initiates a secondary inflammatory response. Regulation of NLRP3 inflammasome ameliorates NLRP3-mediated diseases. Much effort has been invested in studying the activation, and exploration of specific inhibitors and epigenetic mechanisms controlling NLRP3 inflammasome. This review gives an overview of the established NLRP3 inflammasome assembly, its brief molecular mechanistic activations as well as a current update on specific and non-specific NLRP3 inhibitors that could be used in NLRP3-mediated diseases. We also focused on the recently discovered epigenetic mechanisms mediated by DNA methylation, histone alterations, and microRNAs in regulating the activation and expression of NLRP3 inflammasome, which has resulted in a novel method of gaining insight into the mechanisms that modulate NLRP3 inflammasome activity and introducing potential therapeutic strategies for CNS disorders.

Delivery of microRNA-423-5p by exosome from adipose-derived stem/stromal cells inhibits DVL3 to potentiate autologous fat graft survival through adipogenesis and inflammatory response

Autologous fat grafting represents a reconstructive technique but is limited by unstable graft retention. Based on existing reports and bioinformatics prediction, we hypothesized that delivering exosomes from human adipose-derived stem/stromal cells (hADSC-Exo) would increase fat graft survival and further explore the mechanism. hADSC-Exo were extracted and identified. An autologous fat grafting model was established using donor and recipient mice, followed by hADSC-Exo treatment. hADSC-Exo promoted the retention of autologous fat grafts in mice, along with increased adipocyte activity, angiogenesis, and decreased inflammation in grafts. Moreover, hADSC-Exo potentiated the adipose differentiation of 3T3-L1 cells, enhanced the angiogenic and migratory capacity of human umbilical vein endothelial cells, and inhibited the inflammation and viability of RAW 264.7 cells. The therapeutic effect of hADSC-Exo on fat grafting was associated with the delivery of microRNA (miR)-423-5p. Deletion of miR-423-5p in Exo impaired the function of hADSC-Exo on fat retention. miR-423-5p bound to DVL3 to suppress DVL3 expression, and DVL3 deletion promoted adipose differentiation of 3T3-L1 cells. In conclusion, our findings further widen the theoretical basis of the clinical application of hADSC-Exo in autologous fat grafts.

Extracellular vesicles derived from human ESC-MSCs target macrophage and promote anti-inflammation process, angiogenesis, and functional recovery in ACS-induced severe skeletal muscle injury

BACKGROUND

Acute compartment syndrome (ACS) is one of the most common complications of musculoskeletal injury, leading to the necrosis and demise of skeletal muscle cells. Our previous study showed that embryonic stem cells-derived mesenchymal stem cells (ESC-MSCs) are novel therapeutics in ACS treatment. As extracellular vesicles (EVs) are rapidly gaining attention as cell-free therapeutics that have advantages over parental stem cells, the therapeutic potential and mechanisms of EVs from ESC-MSCs on ACS need to be explored.

METHOD

In the present study, we examined the protective effects in the experimental ACS rat model and investigated the role of macrophages in mediating these effects. Next, we used transcriptome sequencing to explore the mechanisms by which ESC-MSC-EVs regulate macrophage polarization. Furthermore, miRNA sequencing was performed on ESC-MSC-EVs to identify miRNA candidates associated with macrophage polarization.

RESULTS

We found that intravenous administration of ESC-MSC-EVs, given at the time of fasciotomy, significantly promotes the anti-inflammation process, angiogenesis, and functional recovery of muscle in ACS. The beneficial effects were associated with ESC-MSC-EVs affecting macrophage polarization by delivering various miRNAs which regulate NF-κB, JAK/STAT, and PI3K/AKT pathways. Our data further illustrate that ESC-MSC-EVs mainly modulate macrophage polarization via the miR-21/PTEN, miR-320a/PTEN, miR-423/NLRP3, miR-100/mTOR, and miR-26a/TLR3 axes.

CONCLUSION

Together, our results demonstrated the beneficial effects of ESC-MSC-EVs in ACS, wherein the miRNAs present in ESC-MSC-EVs regulate the polarization of macrophages.

Sanguisorba officinalis L. promotes diabetic wound healing in rats through inflammation response mediated by macrophage

Sanguisorba officinalis L., a traditional Chinese medicine, is frequently used to treat burns and scalds. But even so, it is unknown whether S. officinalis L. can accelerate diabetic wounds (DW) healing. Here, to bridge the gap, we employed in vivo and in vitro evaluations to assess the positive effect of S. officinalis L. ethanol extract (ESO) on DW. Results demonstrated that ESO dramatically improved the DW healing rate. With ESO treatment, the inappropriately elevated levels of IL6, IL1β and TNFα in DW were reduced, while the expression of IL10 was increased, indicating that the abnormal inflammation in DW was also under control. Moreover, the abnormally elevated expression of CD86 was significantly inhibited and the expression of CD206 was significantly up-regulated following treatment with ESO. The global level of NF-κB protein was not affected by ESO treatment, but it suppressed the expression of phosphorylated NF-κB and prevented its nuclear entry. In addition, in RAW264.7 cells activated with lipopolysaccharide (LPS), the expression of NLRP3, Caspase1 and IL1β were significantly diminished following ESO treatment. In conclusion, ESO was proved to be a promising treatment for DW healing due to its potential to accelerate the healing process by suppressing the inflammatory response. This was achieved by increasing the ratio of M2 to M1 polarization through blocking the NF-κB/NLRP3 signaling pathway.

Osteoblast-Derived Matrix Vesicles Exhibit Exosomal Traits and a Unique Subset of microRNA: Their Caveolae-Dependent Endocytosis Results in Reduced Osteogenic Differentiation

Matrix vesicles (MVs) are nano-sized extracellular vesicles that are anchored in the extracellular matrix (ECM). In addition to playing a role in biomineralization, osteoblast-derived MVs were recently suggested to have regulatory duties. The aims of this study were to establish the characteristics of osteoblast-derived MVs in the context of extracellular vesicles like exosomes, assess their role in modulating osteoblast differentiation, and examine their mechanism of uptake. MVs were isolated from the ECM of MG63 human osteoblast-like cell cultures and characterized via enzyme activity, transmission electron microscopy, nanoparticle tracking analysis, Western blot, and small RNA sequencing. Osteoblasts were treated with MVs from two different culture conditions (growth media [GM]; osteogenic media [OM]) to evaluate their effects on the differentiation and production of inflammatory markers and on macrophage polarization. MV endocytosis was assessed using a lipophilic, fluorescent dye and confocal microscopy with the role of caveolae determined using methyl-β-cyclodextrin. MVs exhibited a four-fold enrichment in alkaline phosphatase specific activity compared to plasma membranes; were 50-150 nm in diameter; possessed exosomal markers CD63, CD81, and CD9 and endosomal markers ALIX, TSG101, and HSP70; and were selectively enriched in microRNA linked to an anti-osteogenic effect and to M2 macrophage polarization. Treatment with GM or OM MVs decreased osteoblast differentiation. Osteoblasts endocytosed MVs using a mechanism that involves caveolae. These results support the hypothesis that osteoblasts produce MVs that participate in the regulation of osteogenesis.

Microneedle/CD-MOF-mediated transdural controlled release of methylprednisolone sodium succinate after spinal cord injury

A new method of transdural delivering drugs to the spinal cord has been developed, involving the use of microneedles (MNs) and a β-cyclodextrin metal-organic framework (CD-MOF). This epidural microneedle array, dubbed MNs@CD-MOF@MPSS, can be utilized to deliver methylprednisolone sodium succinate (MPSS) to the site of spinal cord injury (SCI) in a controlled manner. MNs allows to generate micropores in the dura for direct drug delivery to the spinal cord, overcoming tissue barriers and targeting damaged regions. Additionally, the CD-MOF provides a secondary extended release after separating from the MNs. In in vitro study, inward MNs increased cellular absorption of MPSS and then reduced LPS-induced M1 polarization of microglia. And animal studies have shown that this method of drug delivery results in improved BMS scores and a reduction in M1 phenotype microphage and glial scar formation. Furthermore, the downregulation of the NLRP3-positive inflammasome and related pro-inflammatory cytokines was observed. In conclusion, this new drug platform has potential for clinical application in spinal cord diseases and is a valuable composite for minimally transdural controlled drug delivery. STATEMENT OF SIGNIFICANCE: This research presents a new epidural microneedle patch made up of microneedles (MNs) and a β-cyclodextrin metal-organic framework (CD-MOF). The epidural microneedle patch boasts high drug loading capacity, the ability to penetrate the dura, and controlled release. When loaded with methylprednisolone sodium succinate (MPSS), it effectively reduces inflammation and improves neurological function after spinal cord injury. Therefore, it is a novel and promising drug platform for the treatment of spinal cord diseases in a clinical setting.

MiR-125b-5p/STAT3 Axis Regulates Drug Resistance in Osteosarcoma Cells by Acting on ABC Transporters

Background

The poor prognosis of the highly malignant tumor osteosarcoma stems from its drug resistance and therefore exploring its resistance mechanisms will help us identify more effective treatment options. However, the effects of miR-125b-5p on drug resistance in osteosarcoma cells are still unclear.

Methods

To study the effects of miR-125b-5p on drug resistance in osteosarcoma cells. Osteosarcoma-resistant miR-125b-5p was obtained from the databases GeneCards and g:Profiler. CCK8, western blot, and transwell were applied for the detection of the miR-125b-5p effects on proliferation, migration, invasion, apoptosis, and drug resistance in osteosarcoma. Bioinformatics is aimed at demonstrating the targeting factor miR-125b-5p, performing protein interaction enrichment analysis by Metascape, and finally validating by binding sites.

Results

Upregulation of miR-125b-5p restrains proliferation, migration, and invasion of osteosarcoma and promotes apoptosis. In addition, miR-125b-5p can restore drug sensitivity in drug-resistant osteosarcoma. miR-125-5p restrains the signal transducer and inhibits the transcription 3 (STAT3) expression activator via targeting its 3'-UTR. STAT3 affects drug-resistant osteosarcoma to regulate the ABC transporter.

Conclusion

miR-125b-5p/STAT3 axis mediates the drug resistance of osteosarcoma by acting on ABC transporter.

Pirfenidone-loaded hyaluronic acid methacryloyl hydrogel for preventing epidural adhesions after laminectomy

It is inevitable that scar formation occurs between the spinal dura and surrounding tissues after laminectomy. While extensive epidural fibrosis, which results in limited nerve root activity and severe pain, is the main cause of postoperative failed-back surgery syndrome. Novel biomaterial loading effective drugs based on reasonable design are eagerly needed for the safe and effective prevention of epidural adhesions. We filtrated a suitable dose of pirfenidone (PFD) to load hyaluronic acid methacryloyl (HAMA) hydrogel in vitro. And then, we compare PFD-loaded HAMA hydrogel with only using PFD or HAMA hydrogels after laminectomy by in vivo studies in rats. We describe a safe and efficient anti-adhesive PFD-loaded HAMA hydrogel that prevents epidural fibrosis through the stable and sustained release of PFD. It was shown that the PFD-loaded HAMA hydrogel effectively inhibited cell penetration and suppressed collagen I/III expression. Thus, it effectively prevented the formation of adhesions through pharmacological and physical processes. The PFD-loaded HAMA hydrogel can effectively prevent adhesion formation in both pharmacological and physical barrier effects.

Implications of microglial heterogeneity in spinal cord injury progression and therapy

Microglia are widely distributed in the central nervous system (CNS), where they aid in the maintenance of neuronal function and perform key auxiliary roles in phagocytosis, neural repair, immunological control, and nutrition delivery. Microglia in the undamaged spinal cord is in a stable state and serve as immune monitors. In the event of spinal cord injury (SCI), severe changes in the microenvironment and glial scar formation lead to axonal regeneration failure. Microglia participates in a series of pathophysiological processes and behave both positive and negative consequences during this period. A deep understanding of the characteristics and functions of microglia can better identify therapeutic targets for SCI. Technological innovations such as single-cell RNA sequencing (Sc-RNAseq) have led to new advances in the study of microglia heterogeneity throughout the lifespan. Here,We review the updated studies searching for heterogeneity of microglia from the developmental and pathological state, survey the activity and function of microglia in SCI and explore the recent therapeutic strategies targeting microglia in the CNS injury.

Pyroptosis in spinal cord injury

Spinal cord injury (SCI) often brings devastating consequences to patients and their families. Pathophysiologically, the primary insult causes irreversible damage to neurons and glial cells and initiates the secondary damage cascade, further leading to inflammation, ischemia, and cells death. In SCI, the release of various inflammatory mediators aggravates nerve injury. Pyroptosis is a new pro-inflammatory pattern of regulated cell death (RCD), mainly mediated by caspase-1 or caspase-11/4/5. Gasdermins family are pore-forming proteins known as the executor of pyroptosis and the gasdermin D (GSDMD) is best characterized. Pyroptosis occurs in multiple central nervous system (CNS) cell types, especially plays a vital role in the development of SCI. We review here the evidence for pyroptosis in SCI, and focus on the pyroptosis of different cells and the crosstalk between them. In addition, we discuss the interaction between pyroptosis and other forms of RCD in SCI. We also summarize the therapeutic strategies for pyroptosis inhibition, so as to provide novel ideas for improving outcomes following SCI.

Inhibition of miR-423-5p Exerts Neuroprotective Effects in an Experimental Rat Model of Cerebral Ischemia/Reperfusion Injury

MicroRNAs (miRNAs) are widely acknowledged to play a unique role in cerebrovascular disease. This research investigates the function of microRNAs in ischemic stroke via a middle cerebral artery occlusion (MCAO) model. Four differentially expressed microRNAs in rat brains were identified by bioinformatics analysis, and qRT-PCR showed that miR-423-5p exhibited the highest expression in cerebral ischemia/reperfusion injury in rats, with peak levels observed at 24 hours. After microRNA inhibitors and mimics were administrated in the rat model of MCAO, the neurological scores and brain water content were detected, and triphenyltetrazolium chloride (TTC), Hematoxylin and Eosin (H&E), and Nissl staining were conducted to explore the influence of miR-423-5p on ischemic stroke. Subsequently, western blot, ELISA, MPO, TUNEL and commercial assay kits were applied to assess the influence of miR-423-5p on NLRP3 inflammasome, apoptosis, and oxidative stress levels in ischemic penumbra tissue. The results showed that miR-423-5p knockdown could effectively improve neurological indicators, such as cerebral infarct volume, brain water content, neurological scores, and nerve tissue damage, and inhibit the NLRP3 inflammasome, apoptosis, and oxidative stress. In contrast, the miR-423-5p mimic yielded opposite results. In conclusion, inhibition of miR-423-5p expression could effectively attenuate ischemic stroke and might be considered a promising target for stroke.

Activation of LRP1 Ameliorates Cerebral Ischemia/Reperfusion Injury and Cognitive Decline by Suppressing Neuroinflammation and Oxidative Stress through TXNIP/NLRP3 Signaling Pathway in Mice

Cerebral ischemia/reperfusion (I/R) injury is a clinical event associated with high morbidity and mortality. Neuroinflammation plays a crucial role in the pathogenesis of I/R-induced brain injury and cognitive decline. Low-density lipoprotein receptor-related protein-1 (LRP1) can exert strong neuroprotection in experimental intracerebral hemorrhage. However, whether LRP1 can confer neuroprotective effects after cerebral I/R is yet to be elucidated. The present study is aimed at investigating the effects of LRP1 activation on cerebral I/R injury and deducing the underlying mechanism involving TXNIP/NLRP3 signaling pathway. Cerebral I/R injury was induced in mice by bilateral common carotid artery occlusion. LPR1 ligand, apoE-mimic peptide COG1410, was administered intraperitoneally. To elucidate the underlying mechanism, overexpression of TXNIP was achieved via the hippocampal injection of AAV-TXNIP before COG1410 treatment. Neurobehavioral tests, brain water content, immunofluorescence, Western blot, enzyme-linked immunosorbent assay, HE, and terminal deoxynucleotidyl transferase dUTP nick end labeling staining were performed. Our results showed that the expressions of endogenous LRP1, TXNIP, NLRP3, procaspase-1, and cleaved caspase-1 were increased after cerebral I/R. COG1410 significantly ameliorated cerebral I/R-induced neurobehavioral deficits, brain edema, histopathological damage, and poor survival rate. Interestingly, COG1410 inhibited microglia proinflammatory polarization and promoted anti-inflammatory polarization, decreased oxidative stress, attenuated apoptosis, and inhibited the expression of the TXNIP/NLRP3 signaling pathway. However, the benefits of COG1410 were abolished by TXNIP overexpression. Thus, our study suggested that LRP1 activation with COG1410 attenuated cerebral I/R injury at least partially related to modulating microglial polarization through TXNIP/NLRP3 signaling pathway in mice. Thus, COG1410 treatment might serve as a promising therapeutic approach in the management of cerebral I/R patients.

HBO Alleviates Neural Stem Cell Pyroptosis via lncRNA-H19/miR-423-5p/NLRP3 Axis and Improves Neurogenesis after Oxygen Glucose Deprivation

Due to the limited neurogenesis capacity, there has been a big challenge in better recovery from neurological dysfunction caused by stroke for a long time. Neural stem cell (NSC) programmed death is one of the unfavorable factors for neural regeneration after stroke. The types of death such as apoptosis and necroptosis have been deeply investigated while the pyroptosis of NSCs is not quite understood. Although it is well accepted that hyperbaric oxygen (HBO) alleviates the oxygen-glucose deprivation (OGD) injury after stroke and reduces programmed death of NSCs, whether NSC pyroptosis is involved in this process is still unknown. Therefore, this study is aimed at studying the potential effect of HBO treatment on NSC pyroptosis following OGD exposure, as well as its influence on NSC proliferation and differentiation in vitro. The results revealed that OGD increased NOD-like receptor protein 3 (NLRP3) expression to induce the pyroptotic death of NSCs, which was rescued by HBO treatment. And the upregulated lncRNA-H19 functioned as a molecular sponge of miR-423-5p to target NLRP3 for NSC pyroptosis following OGD. Most importantly, it was confirmed that HBO exerted protection of NSCs against pyroptosis by inhibiting lncRNA-H19/miR-423-5p/NLRP3 axis. Moreover, HBO restraint of lncRNA-H19-associated pyroptosis benefited the proliferation and neuronal differentiation of NSCs. It was concluded that HBO attenuated NSC pyroptosis via lncRNA-H19/miR-423-5p/NLRP3 axis and enhanced neurogenesis following OGD. The findings provide new insight into NSC programmed death and enlighten therapeutic strategy after stroke.

TI: NLRP3 Inflammasome-Dependent Pyroptosis in CNS Trauma: A Potential Therapeutic Target

Central nervous system (CNS) trauma, including traumatic brain injury (TBI) and traumatic spinal cord injury (SCI), is characterized by high morbidity, disability, and mortality. TBI and SCI have similar pathophysiological mechanisms and are often accompanied by serious inflammatory responses. Pyroptosis, an inflammation-dependent programmed cell death, is becoming a major problem in CNS post-traumatic injury. Notably, the pyrin domain containing 3 (NLRP3) inflammasome is a key protein in the pyroptosis signaling pathway. Therefore, underlying mechanism of the NLRP3 inflammasome in the development of CNS trauma has attracted much attention. In this review, we briefly summarize the molecular mechanisms of NLRP3 inflammasome in pyroptosis signaling pathway, including its prime and activation. Moreover, the dynamic expression pattern, and roles of the NLRP3 inflammasome in CNS post-traumatic injury are summarized. The therapeutic applications of NLRP3 inflammasome activation inhibitors are also discussed.