Tetramethylpyrazine promotes axonal remodeling and modulates microglial polarization via JAK2-STAT1/3 and GSK3-NFκB pathways in ischemic stroke

Remote Ischemic Post-conditioning Reduces Cognitive Impairment in Rats Following Subarachnoid Hemorrhage: Possible Involvement in STAT3/STAT5 Phosphorylation and Th17/Treg Cell Homeostasis

The inflammatory response following subarachnoid hemorrhage (SAH) may lead to Early Brain Injury and subsequently contribute to poor prognosis such as cognitive impairment in patients. Currently, there is a lack of effective strategies for SAH to ameliorate inflammation and improve cognitive impairment in clinical. This study aims to examine the inhibitory impact of remote ischemic post-conditioning (RIPostC) on the body's inflammatory response by regulating Th17/Treg cell homeostasis after SAH. The ultimate goal is to search for potential early treatment targets for SAH. The rat SAH models were made by intravascular puncture of the internal carotid artery. The intervention of RIPostC was administered for three consecutive days immediately after successful modeling. Behavioral experiments including the Morris water maze and Y-maze tests were conducted to assess cognitive functions such as spatial memory, working memory, and learning abilities 2 weeks after successful modeling. The ratio of Th17 cells and Treg cells in the blood was detected using flow cytometry. Immunofluorescence was used to observe the infiltration of neutrophils into the brain. Signal transducers and activators of transcription 5 (STAT5) and signal transducers and activators of transcription 3 (STAT3) phosphorylation levels, receptor-related orphan receptor gamma-t (RORγt), and forkhead box protein P3 (Foxp3) levels were detected by Western blot. The levels of anti-inflammatory factors (IL-2, IL-10, IL-5, etc.) and pro-inflammatory factors (IL-6, IL-17, IL-18, TNF-α, IL-14, etc.) in blood were detected using Luminex Liquid Suspension Chip Assay. RIPostC significantly improved the cognitive impairment caused by SAH in rats. The results showed that infiltration of Th17 cells and neutrophils into brain tissue increased after SAH, leading to the release of pro-inflammatory factors (IL-6, IL-17, IL-18, and TNF-α). This response can be inhibited by RIPostC. Additionally, RIPostC facilitates the transfer of Treg from blood to the brain and triggers the release of anti-inflammatory (IL-2, IL-10, and IL-5) factors to suppress the inflammation following SAH. Finally, it was found that RIPostC increased the phosphorylation of STAT5 while decreasing the phosphorylation of STAT3. RIPostC reduces inflammation after SAH by partially balancing Th17/Treg cell homeostasis, which may be related to downregulation of STAT3 and upregulation of STAT5 phosphorylation, which ultimately alleviates cognitive impairment in rats. Targeting Th17/Treg cell homeostasis may be a promising strategy for early SAH treatment.

Enhanced inhibition of neuronal ferroptosis and regulation of microglial polarization with multifunctional traditional Chinese medicine active ingredients-based selenium nanoparticles for treating spinal cord injury

Spinal cord injury (SCI) is a devastating condition that results in the loss of sensory and motor functions. The complex pathogenesis of SCI contributes to the limited availability of effective therapies. Two major factors exacerbating secondary injury in SCI are neuronal ferroptosis and microglial inflammatory polarization. Tanshinone IIA (TSIIA) has demonstrated a significant anti-ferroptosis effect by inhibiting lipid peroxidation, while tetramethylpyrazine (TMP) exhibits remarkable anti-inflammatory properties by promoting the shift of microglial polarization from the M1 to the M2 phenotype. However, most drugs currently under development primarily target a single aspect of this multifaceted condition, which is insufficient for comprehensive treatment. Selenium nanoparticles have emerged as a promising therapeutic strategy due to their ability to encapsulate various agents, effectively targeting diverse pathophysiological mechanisms while offering favorable water solubility and low toxicity. In this study, we developed a novel nanocarrier functionalized with astragalus polysaccharide (APS) and loaded with TSIIA and TMP. Results from both in vitro and in vivo studies indicate that TSIIA/TMP/APS@Se NPs possess anti-ferroptosis properties and can regulate microglial polarization, potentially enhancing functional recovery following SCI. In summary, this study presents a promising alternative strategy for treating SCI, highlighting its significant potential for future clinical applications.

Buyang Huanwu decoction improves motor function by enhancing internal capsule reorganization through inhibiting Notch signaling after ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Buyang Huanwu Decoction (BHD) is a common traditional Chinese medicine formula that has been used for the treating post-stroke disability for centuries. Nevertheless, the impact of BHD on internal capsule injury following stroke remains unknown and warrants further investigation.

AIM OF THE STUDY

This study aimed to assess the efficacy of BHD on post-stroke internal capsule integrity by using an in vivo magnetic resonance imaging (MRI) technique and further explore the potential mechanisms by which BHD facilitates internal capsule reorganization after ischemic stroke.

MATERIALS AND METHODS

Male Sprague-Dawley rats were subjected to permanent occlusion of the middle cerebral artery (MCAO) to induce focal cerebral ischemia. BHD was intragastrically administered at doses of 16.6 g/kg and 8.3 g/kg to rats once daily for 30 consecutive days. Subsequently, an automated Digi gait system was utilized to assess the motor function. MRI examinations, including T2 relaxometry mapping and diffusion tensor imaging (DTI), were conducted to detect structural alterations in the internal capsule. Moreover, diffusion tractography was performed to evaluate internal capsule remodeling. Pearson correlation analysis was conducted between the gait and MRI parameters. Additionally, luxol fast blue (LFB) staining was performed for pathological assessment of the internal capsule. Double immunofluorescence staining was carried out to evaluate remyelination and Notch signaling activation in the injured internal capsule.

RESULTS

The gait analysis revealed that BHD treatment significantly decreased stance time while elevating swing time, stride length, and paw area of the MCAO rats. T2 mapping indicated obvious infarction and an elevated T2 value, and DTI detected reduced fractional anisotropy but increased radial diffusivity in the internal capsule following MCAO. LFB staining further confirmed demyelination in the injured internal capsule. However, BHD interventions effectively reversed these MRI abnormalities and demyelination, and improved fiber density and length of the internal capsule. Notably, the gait performances were strongly correlated to the T2 value, fiber density, and fiber length of the internal capsule. Particularly, BHD treatments facilitated oligodendrogenesis in the internal capsule by elevating the numbers of Ki67/NG2, Ki67/Oligo2, and Ki67/CNPase positive cells. Furthermore, BHD effectively inhibited the activation of Notch signaling in the oligodendrocyte precursor cells (OPCs), as evidenced by reduced numbers of NG2/Notch1, NG2/NICD, and NG2/Hes5 positive cells.

CONCLUSION

The present study demonstrated that BHD could promote post-stroke motor recovery by alleviating structural damage to the internal capsule and facilitating internal capsule reorganization. Notably, BHD treatment enhanced oligodendrogenesis and subsequent remyelination by inhibiting Notch signaling activation in the OPCs.

Ligustrazine Alleviates Blood-Brain Barrier Damage by Downregulating Expression of miR-297c-5p

OBJECTIVE

Ligustrazine (LSZ), an ingredient of Ligusticum chuanxiong, has long been used to treat neurovascular diseases in China. This study investigates its protective effects for the impairment of the blood-brain barrier (BBB) and the underlying mechanisms.

METHODS

In this study, the impacts of LSZ on the BBB function were firstly assessed in b. End3 cells in vitro. Oxygen-glucose deprivation (OGD) served as an injury factor and western blot (WB) analyzed the expressions of occludin and ZO-1, two tight junction proteins (TJs), essential for maintaining the integrity of the BBB. After bioinformatics analysis of the transcriptome in vivo, qRT-PCR of miR-297c-5p was conducted and a dual-luciferase reporter assay was used to verify the target protein, occludin, which was confirmed by hippocampal insertion using guide cannulas and microinfection of RNA oligos.

RESULTS

A 3-h deprivation of OGD of b. End3 cells resulted in noticeable reductions in the level of occludin and ZO-1. However, administration of LSZ (0.1 μM) effectively restored these decreases. In normal mice, administration of LSZ (25 mg/kg, i.p., once daily for 9 days) resulted in a notable reduction in miR-297c-5p. In the middle cerebral artery occlusion (MCAO) mouse model, increased miR-297c-5p was also reversed by LSZ administration. Bioinformatics analysis revealed one of the targets of miR-297c-5p includes occludin. MiR-297c-5p was found to directly target occludin in the dual-luciferase reporter assay. Transfection of miR-297c-5p agomir into b. End3 cells resulted in a significant reduction in the level of occludin, while transfection of antagomir led to an increase in occludin. Besides, stereotaxic injection of AAV-miR-297c-5p into the hippocampus reduced occludin level in vivo. Ultimately, hippocampal microinfection of RNA oligos provided a confirmation that miR-297c-5p was downregulated by LSZ in MCAO mice with up-regulated occludin expression.

CONCLUSION

In conclusion, the present findings provide new insights into regulating occludin by LSZ through downregulation of miR-297c-5p.

Anti-TNFα and Anti-IL-1β Monoclonal Antibodies Preserve BV-2 Microglial Homeostasis Under Hypoxia by Mitigating Inflammatory Reactivity and ATF4/MAPK-Mediated Apoptosis

The disruption of microglial homeostasis and cytokine release are critical for neuroinflammation post-injury and strongly implicated in retinal neurodegenerative diseases like glaucoma. This study examines microglial responses to chemical hypoxia induced by cobalt chloride (CoCl2) in BV-2 murine microglial cells, focusing on signaling pathways and proteomic alterations. We assessed the protective effects of monoclonal antibodies against TNFα and IL-1β. CoCl2 exposure led to decreased cell viability, reduced mitochondrial membrane potential, increased lactate dehydrogenase release, elevated reactive oxygen species generation, and activation of inflammatory pathways, including nitric oxide synthase (iNOS), STAT1, and NF-κB/NLRP3. These responses were significantly mitigated by treatment with anti-TNFα and anti-IL-1β, suggesting their dual role in reducing microglial damage and inhibiting inflammatory reactivity. Additionally, these treatments reduced apoptosis by modulating ATF4 and the p38 MAPK/caspase-3 pathways. Label-free quantitative mass spectrometry-based proteomics and Gene Ontology revealed that CoCl2 exposure led to the upregulation of proteins primarily involved in endoplasmic reticulum and catabolic processes, while downregulated proteins are associated with biosynthesis. Anti-TNFα and anti-IL-1β treatments partially restored the proteomic profile toward normalcy, with network analysis identifying heat shock protein family A member 8 (HSPA8) as a central mediator in recovery. These findings offer insights into the pathogenesis of hypoxic microglial impairment and suggest potential therapeutic targets.

Investigating the Potential Therapeutic Targeting of the JAK-STAT Pathway in Cerebrovascular Diseases: Opportunities and Challenges

Cerebrovascular disease (CVD) is a significant neurological condition resulting from pathological changes in the brain's blood supply and is currently the leading cause of death and disability worldwide. The progression of CVD is closely associated with endothelial damage, plaque formation, and thrombosis, driven by long-term alterations in vascular endothelial cells, smooth muscle cells, microglia, and other immune-inflammatory cells. Among the key molecular pathways involved, the Janus kinase/signal transducer and activator of transcription (JAK-STAT) signaling pathway plays a central role. Dysregulation of the JAK-STAT pathway is implicated in the pathogenesis of CVD by influencing the aforementioned cell types and associated pathological processes. Importantly, the role of the JAK-STAT pathway varies across different types of CVD and throughout different stages of disease progression (e.g., pre-morbid, acute, and chronic phases). This review examines the composition, activation, and regulation of the JAK-STAT pathway and summarizes recent findings on its involvement in CVD. We discuss the distinct roles of JAK-STAT signaling in various CVD conditions, the potential reasons for these differences, and explore the clinical translational prospects and technical challenges of targeting the JAK-STAT pathway for therapeutic intervention in CVD.

Buyang Huanwu decoction promotes gray and white matter remyelination by inhibiting Notch signaling activation in the astrocyte and microglia after ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Ischemic stroke causes damages to both gray and white matter, resulting in long-term motor impairments. Myelin repair is a promising strategy for poststroke motor rehabilitation. Buyang Huanwu Decoction (BHD) is a classical traditional Chinese medicine formula for managing the sequelae of ischemic stroke. Whether BHD benefits gray and white matter remyelination following stroke remains to be elucidated.

AIM OF THE STUDY

The present study aimed to investigate the effects of BHD on the gray and white matter remyelination following ischemic stroke and further explore the underlying mechanisms by combining magnetic resonance imaging (MRI) and histological experiments.

MATERIALS AND METHODS

The ischemic stroke model was established in male Sprague-Dawley rats by permanently occluding the middle cerebral artery (MCAO). BHD (16.6 g/kg and 8.3 g/kg) was intragastrically administered to rats for 30 days. The motor function was assessed by an automated Digi gait system. The structural integrity of the motor cortex and external capsule was monitored by MRI, including T2 mapping and diffusion tensor imaging (DTI). The remyelination was examined by Olig2/Ki67, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)/Ki67 double immunofluorescence staining and Luxol fast blue (LFB) staining. Subsequently, the Notch signaling activation in astrocytes and microglia was assessed by double immunofluorescence staining with JAG1/Notch1/Notch intracellular domain (NICD) and glial fibrillary acidic protein (GFAP)/ionized calcium binding adaptor molecule 1 (Iba1).

RESULTS

BHD treatments remarkably improved motor function of the MCAO rats by reducing steps, swing time and ataxia coefficient of the left forelimb. The MRI examinations found that BHD treatments significantly reduced infarct volume and preserved the motor cortex and external capsule integrity, as reflected by decreased T2 values, RD, and increased FA. Notably, the gait parameters of the left forelimb were correlated to the MRI index obtained from the perilesional motor cortex and external capsule to varying degrees. Furthermore, BHD treatments enhanced gray and matter remyelination by elevating the numbers of Olig2+/Ki67+, CNPase+/Ki67+ cells, and the integrated optical density of LFB. Finally, BHD effectively inhibited the activation of Notch signaling in the astrocytes and microglia of the corresponding gray and white matter, as evidenced by decreased numbers of cells co-expressing JAG1/Notch1/NICD and GFAP/Iba1.

CONCLUSION

This study demonstrated that BHD treatment could promote poststroke motor recovery by preserving the structural integrity of the gray and white matter and facilitating their remyelination. Notably, the pro-remyelination effects of BHD treatment might be attributed to suppressed activation of Notch signaling within the reactive astrocytes and microglia.

Mitochondria-Targeted Biomaterials-Regulating Macrophage Polarization Opens New Perspectives for Disease Treatment

Macrophage immunotherapy is an emerging therapeutic approach designed for modulating the immune response to alleviate disease symptoms. The balance between pro-inflammatory and anti-inflammatory macrophages plays a pivotal role in the progression of inflammatory diseases. Mitochondria, often referred to as the "power plants" of the cell, are essential organelles responsible for critical functions such as energy metabolism, material synthesis, and signal transduction. The functional state of mitochondria is closely linked to macrophage polarization, prompting interest in therapeutic strategies that target mitochondria to regulate this process. To this end, biomaterials with excellent targeting capabilities and effective therapeutic properties have been developed to influence mitochondrial function and regulate macrophage polarization. However, a comprehensive summary of biomaterial-driven modulation of mitochondrial function to control macrophage phenotypes is still lacking. This review highlights the critical role of mitochondrial function in macrophage polarization and discusses therapeutic strategies mediated by biomaterials, including mitochondria-targeted biomaterials. Finally, the prospects and challenges of the use of these biomaterials in disease modulation have been explored, emphasizing their potential to be translated to the clinic. It is anticipated that this review will serve as a valuable resource for materials scientists and clinicians in the development of next-generation mitochondria-targeted biomaterials.

Tetramethylpyrazine attenuates cerebral ischemia-reperfusion injury by inhibiting ferroptosis via the AMPK / Nrf2 pathways

OBJECTIVES

Ferroptosis is involved in the development and exacerbation of cerebral ischemia-reperfusion injury (CIRI), and its inhibition can alleviate CIRI. Tetramethylpyrazine (TMP) is used for the treatment of ischemic stroke. However, the mechanism by which TMP regulates ferroptosis in CIRI is yet to be explored. This study demonstrated the effects of TMP on ferroptosis and CIRI, including the roles of the adenosine 5'-monophosphate-activated protein kinase (AMPK)/nuclear factor erythroid-2-related factor 2 (Nrf2) signaling pathway.

MATERIALS AND METHODS

A Sprague-Dawley rat middle cerebral artery occlusion/reperfusion (MCAO/R) model was generated. The extent of neuronal injury was measured using 2,3,5-triphenyl tetrazolium chloride staining and Garcia neurological scoring and behavior was evaluated using open-field tests. Ferroptosis-related indexes were examined and ferroptosis-related proteins were detected using western blotting. The binding modes of TMP and AMPK were evaluated using molecular docking and molecular dynamics simulations.

RESULTS

MCAO/R rats showed a reduced cerebral infarct area and improved neurological function after TMP intervention. TMP reduced levels of Fe2+, 4-hydroxynonenal, malonaldehyde, and acyl-coenzyme synthetase long-chain family member 4 and increased levels of glutathione and glutathione peroxidase 4. Increased AMPK phosphorylation and Nrf2 expression were also detected. TMP bound tightly to the AMPKα subunit in silico, and the LEU157, VAL41, LEU33, VAL107, and TYR106 residues were important for binding.

CONCLUSIONS

Our results indicate that TMP can alleviate CIRI by inhibiting ferroptosis via the activation of the AMPK/Nrf2 pathway, providing a theoretical basis for the clinical use of TMP in treating CIRI.

NDUFA11 may be the disulfidptosis-related biomarker of ischemic stroke based on integrated bioinformatics, clinical samples, and experimental analyses

Background

Programmed cell death plays an important role in neuronal injury and death after ischemic stroke (IS), leading to cellular glucose deficiency. Glucose deficiency can cause abnormal accumulation of cytotoxic disulfides, resulting in disulfidptosis. Ferroptosis, apoptosis, necroptosis, and autophagy inhibitors cannot inhibit this novel programmed cell death mechanism. Nevertheless, the potential mechanisms of disulfidptosis in IS remain unclear.

Methods

The GSE16561 dataset was used to screen for differentially expressed disulfidptosis-related biomarkers (DE-DRBs). A correlation between the DE-DRBs was detected. The optimal machine-learning (ML) model and predictor molecules were determined. The GSE58294 dataset was used to verify the accuracy of the optimal ML model. The DE-DRB expression was detected in the blood of patients with IS. Based on IS models, experimental analyses were performed to verify DE-DRB expression and the correlation between DE-DRBs.

Results

Leucine-rich pentatricopeptide repeat-containing (LRPPRC) and NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 11 (NDUFA11) were identified as DE-DRBs. The NADH: ubiquinone oxidoreductase core subunit S1 (NDUFS1) interacted with NDUFA11 and LRPPRC. The support vector machine (SVM) model was identified as the optimal ML model. The NDUFA11 expression level in the blood of patients with IS was 20.9% compared to that in normal controls. NDUFA11 expression was downregulated in the in vitro/in vivo models of IS. The number of formed complexes of NDUFS1 and NDUFA11 decreased in the in vitro/in vivo models of IS.

Conclusion

This research suggests that NDUFA11 is a specific DRB for IS and demonstrates alterations in the disulfidptosis-related protein complexes NDUFS1-NDUFA11.

MRS3997, a dual adenosine A2A/A2B receptor agonist, reduces brain ischemic damage and alleviates neuroinflammation in rats

The endogenous neuromodulator adenosine is massively released during hypoxic/ischemic insults and differentially modulates post-ischemic damage depending on the expression and recruitment of its four metabotropic receptor subtypes, namely A1, A2A, A2B and A3 receptors (A1Rs, A2ARs, A2BRs and A3Rs). We previously demonstrated, by using a model of transient middle cerebral artery occlusion (tMCAo) in rats, that selective activation of A2ARs, as well as A2BRs, ameliorates post-ischemic brain damage in contrast to neuroinflammation. In the present study, we investigated whether the multitarget nucleoside MRS3997, a full agonist at both A2ARs and A2BRs, would afford higher neuroprotection in post-ischemic damage. Chronic systemic treatment with MRS3997 reduced neurological deficit, body weight loss and infarct volume in the cortex and striatum measured 7 days after ischemia. The dual agonist counteracted neuronal loss, reduced myelin damage, and prevented morphological changes indicative of microglia and astrocyte activation. Finally, MRS3997 shifted plasma cytokine levels to an anti-inflammatory profile. These effects were preceded, at 2 days after the insult, by a reduced granulocyte infiltration in the ischemic cortex and, differently from what was observed with selective A2AR or A2BR agonism, also in striatum. In summary, we demonstrate here that MRS3997, systemically administered for 7 days after tMCAO, protects ischemic areas from neuronal and glial damage and inhibits neuroinflammation, therefore representing an attractive strategy to ameliorate post-stroke damage and neurological symptoms.

ACTH-like Peptides Compensate Rat Brain Gene Expression Profile Disrupted by Ischemia a Day After Experimental Stroke

Background: Ischemic stroke results from a disruption of cerebral blood flow. Adrenocorticotropic hormone (ACTH) serves as the basis for the creation of synthetic peptides as neuroprotective agents for stroke therapy. Previously, using RNA-Seq we first revealed differential expressed genes (DEGs) associated with ACTH(4-7)PGP (Semax) and ACTH(6-9)PGP peptides under cerebral ischemia conditions. Analysis was carried out at 4.5 h after transient middle cerebral artery occlusion (tMCAO) model in the ipsilateral frontal cortex of a rat brain. Methods: Here, we analyzed the penumbra-associated frontal cortex of rats and actions under the same peptides at 24 h after tMCAO using RNA-Seq. Results: 3774 DEGs (fold change > 1.5 and Padj < 0.05) were identified under ischemia conditions, whereas 1539 and 2066 DEGs were revealed under Semax and ACTH(6-9)PGP peptides at 24 h after tMCAO. Furthermore, both peptides significantly reduced expression distortions caused by ischemia for 1171 genes associated with immune and neurosignaling pathways. Concomitantly, there were 32 DEGs under ACTH(6-9)PGP versus Semax administration at 24 h after tMCAO. Besides, neurogenesis-, angiogenesis-, protein kinase- and growth factor-related DEGs were revealed under peptides action. Previously, we observed the neuroprotective effect of peptides at the histological level in rat brains at 24 h after tMCAO. Thus, here we demonstrate the transcriptome manifestation of this histological effect. Furthermore, comparison with previous data at the 4.5 h post-tMCAO time point showed that the pattern of peptide action on the transcriptome depends on the time elapsed after tMCAO. Conclusions: We revealed that the effect of ACTH(6-9)PGP was more similar to Semax than different from it a day after tMCAO. At this time point, ACTH-like peptides compensated rat brain gene expression profiles disrupted by ischemia. Thus, our results may be useful for selecting more effective structures for future anti-stroke drugs and appropriate post-stroke time points for their testing.

Astragaloside IV promotes cerebral tissue restoration through activating AMPK- mediated microglia polarization in ischemic stroke rats

ETHNOPHARMACOLOGICAL RELEVANCE

Astragaloside IV (AS), a key active ingredient obtained from Chinese herb Astragalus mongholicus Bunge, exerts potent neuroprotective and anti-inflammatory effects for treating neurodegenerative diseases. However, mechanisms of AS on improvement of ischemic brain tissue repair remain unclear.

AIM OF THE STUDY

This research aims at using magnetic resonance imaging (MRI) to noninvasively determine whether AS facilitates brain tissue repair, and investigating whether AS exerts brain remodeling through adenosine monophosphate-activated protein kinase (AMPK) metabolic signaling regulating key glycolytic enzymes and energy transporters, thereby impacting microglia polarization.

MATERIALS AND METHODS

Ischemic stroke model in male Sprague-Dawley rats were induced through permanent occlusion of the middle cerebral artery (MCAO). Infarct volume, the alterations of brain microstructure and nerve fibers reorganization were examined by multi-parametric MRI. The pathological damages of myelinated axons and microglia polarization surrounding infarct tissue were detected using pathological techniques. Furthermore, M1/M2 microglia polarization associated protein, glycolytic rate-limiting enzymes, energy transporters and AMPK/mammalian target of rapamycin (mTOR)/hypoxia inducible factor-1α (HIF-1α) signal were examined both in ischemic stroke rats and BV2 microglia treated with lipopolysaccharide (LPS) + interferon-γ (IFN-γ) by western blotting.

RESULTS

MRI revealed that AS obviously decreased infarct volume, relieved brain microstructure damage and improved nerve fibers reorganization in ischemic stroke rats. Histological tests supported MRI findings. Notably, AS promoted microglia M2 and reduced M1 polarization, induced the AMPK activation accompanied with decreased levels of phosphorylated mTOR and HIF-1α. Moreover, AS suppressed the expression of glycolytic rate-limiting enzymes and energy transporters in ischemic stroke rats and BV2 microglia. In contrast, these beneficial effects were greatly blocked by AMPK inhibitor compound C.

CONCLUSION

Overall, these results collectively suggested that AS facilitated tissue remodeling that may be partially through modulating polarization of microglia in AMPK- dependent metabolic pathways after ischemic stroke.

Synergistic amelioration between Ligusticum striatum DC and borneol against cerebral ischemia by promoting astrocytes-mediated neurogenesis

ETHNOPHARMACOLOGICAL RELEVANCE

Ligusticum chuanxiong Hort (LCH), with the accepted name of Ligusticum striatum DC in "The Plant List" database, is a widely used ethnomedicine in treating ischemic stroke, and borneol (BO) is usually prescribed with LCH for better therapy. Our previous study confirmed their synergistic effect on neurogenesis against cerebral ischemia. However, the underlying mechanism is still unclear.

AIM OF THE STUDY

More and more evidence indicated that astrocytes (ACs) might be involved in the modulation of neurogenesis via polarization reaction. The study was designed to explore the synergic mechanism between LCH and BO in promoting astrocyte-mediated neurogenesis.

MATERIALS AND METHODS

After primary cultures and identifications of ACs and neural stem cells (NSCs), the oxygen-glucose deprivation (OGD) model and the concentrations of LCH and BO were optimized. After the OGD-injured ACs were treated by LCH, BO, and their combination, the conditioned mediums were used to culture the OGD-injured NSCs. The proliferation, migration, and differentiation of NSCs were assessed, and the secretions of BDNF, CNTF, and VEGF from ACs were measured. Then the expressions of C3 and PTX3 were detected. Moreover, the mice were performed a global cerebral ischemia/reperfusion model and treated with LCH and (or) BO. After the assessments of Nissl staining, the expressions of Nestin, DCX, GFAP, C3, PTX3, p65 and p-p65 were probed.

RESULTS

The most appropriate duration of OGD for the injury of both NSCs and ACs was 6 h, and the optimized concentrations of LCH and BO were 1.30 μg/mL and 0.03 μg/mL, respectively. The moderate OGD environment induced NSCs proliferation, migration, astrogenesis, and neurogenesis, increased the secretions of CNTF and VEGF from ACs, and upregulated the expressions of C3 and PTX3. For the ACs, LCH further increased the secretions of BDNF and CNTF, enhanced PTX3 expression, and reduced C3 expression. Additionally, the conditioned medium from LCH-treated ACs further enhanced NSC proliferation, migration, and neurogenesis. The in vivo study showed that LCH markedly enhanced the Nissl score and neurogenesis, and decreased astrogenesis which was accompanied by downregulations of C3, p-p65, and p-p65/p65 and upregulation of PTX3. BO not only decreased the expression of C3 in ACs both in vitro and in vivo but also downregulated p-p65 and p-p65/p65 in vivo. Additionally, BO promoted the therapeutic effect of LCH for most indices.

CONCLUSION

A certain degree of OGD might induce ACs to stimulate the proliferation, astrogenesis, and neurogenesis of NSCs. LCH and BO exhibited a marked synergy in promoting ACs-mediated neurogenesis and reducing astrogenesis, in which LCH played a dominant role and BO boosted the effect of LCH. The mechanism of LCH might be involved in switching the polarization of ACs from A1 to A2, while BO preferred to inhibit the formation of A1 phenotype via downregulating NF-κB pathway.

Microglia and Stem Cells for Ischemic Stroke Treatment-Mechanisms, Current Status, and Therapeutic Challenges

Ischemic stroke is one of the major causes of death and disability. Since the currently used treatment option of reperfusion therapy has several limitations, ongoing research is focusing on the neuroprotective effects of microglia and stem cells. By exerting the bystander effect, secreting exosomes and forming biobridges, mesenchymal stem cells (MSCs), neural stem cells (NSCs), induced pluripotent stem cells (iPSCs), and multilineage-differentiating stress-enduring cells (Muse cells) have been shown to stimulate neurogenesis, angiogenesis, cell migration, and reduce neuroinflammation. Exosome-based therapy is now being extensively researched due to its many advantageous properties over cell therapy, such as lower immunogenicity, no risk of blood vessel occlusion, and ease of storage and modification. However, although preclinical studies have shown promising therapeutic outcomes, clinical trials have been associated with several translational challenges. This review explores the therapeutic effects of preconditioned microglia as well as various factors secreted in stem cell-derived extracellular vesicles with their mechanisms of action explained. Furthermore, an overview of preclinical and clinical studies is presented, explaining the main challenges of microglia and stem cell therapies, and providing potential solutions. In particular, a highlight is the use of novel stem cell therapy of Muse cells, which bypasses many of the conventional stem cell limitations. The paper concludes with suggestions for directions in future neuroprotective research.