IMM-H004 protects against oxygen-glucose deprivation/reperfusion injury to BV2 microglia partly by modulating CKLF1 involved in microglia polarization

Utility of serum chemokine-like factor 1 as a biomarker of severity and prognosis after severe traumatic brain injury: A prospective observational study

BACKGROUND

Chemokine-like factor 1 (CKLF1) may be involved in the inflammatory response and secondary brain injury after severe traumatic brain injury (sTBI). We determined serum CKLF1 levels of sTBI patients to further investigate the correlation of CKLF1 levels with disease severity, functional prognosis, and 180-day mortality of sTBI.

METHODS

Serum CKLF1 levels were measured at admission in 119 sTBI patients and at entry into study in 119 healthy controls. Serum CKLF levels of 50 patients were also quantified at days 1-3, 5, and 7 after admission. Glasgow coma scale (GCS) scores and Rotterdam computerized tomography (CT) classification were utilized to assess disease severity. Extended Glasgow outcome scale (GOSE) scores were recorded to evaluate function prognosis at 180 days after sTBI. Relations of serum CKLF1 levels to 180-day poor prognosis (GOSE scores of 1-4) and 180-day mortality were analyzed using univariate analysis, followed by multivariate analysis. Receiver-operating characteristic (ROC) curve was built to investigate prognostic predictive capability.

RESULTS

Serum CKLF1 levels of sTBI patients increased at admission, peaked at day 2, and then gradually decreased; they were significantly higher during the 7 days after sTBI than in healthy controls. Differences of areas under ROC curve (areas under the curve [AUCs]) were not significant among the six time points. Multivariate analysis showed that serum CKLF1 levels were independently correlated with GCS scores, Rotterdam CT classification, and GOSE scores. Serum CKLF1 levels were significantly higher in non-survivors than in survivors and in poor prognosis patients than in good prognosis patients. Serum CKLF1 levels independently predicted 180-day poor prognosis and 180-day mortality, and had high 180-day prognosis and mortality predictive abilities, and their AUCs were similar to those of GCS scores and Rotterdam CT classification. Combination model containing serum CKLF1, GCS scores, and Rotterdam CT classification performed more efficiently than any of them alone in predicting mortality and poor prognosis. The models were visually described using nomograms, which were comparatively stable under calibration curve and were relatively of clinical benefit under decision curve.

CONCLUSION

Serum CKLF1 levels are significantly associated with disease severity, poor 180-day prognosis, and 180-day mortality in sTBI patients. Hence, complement CKLF1 may serve as a potential prognostic biomarker of sTBI.

CKLF induces microglial activation via triggering defective mitophagy and mitochondrial dysfunction

Although microglial activation is induced by an increase in chemokines, the role of mitophagy in this process remains unclear. This study aimed to elucidate the role of microglial mitophagy in CKLF/CKLF1 (chemokine-like factor 1)-induced microglial activation and neuroinflammation, as well as the underlying molecular mechanisms following CKLF treatment. This study determined that CKLF, an inducible chemokine in the brain, leads to an increase in mitophagy markers, such as DNM1L, PINK1 (PTEN induced putative kinase 1), PRKN, and OPTN, along with a simultaneous increase in autophagosome formation, as evidenced by elevated levels of BECN1 and MAP1LC3B (microtubule-associated protein 1 light chain 3 beta)-II. However, SQSTM1, a substrate of autophagy, was also accumulated by CKLF treatment, suggesting that mitophagy flux was reduced and mitophagosomes accumulated. These findings were confirmed by transmission electron microscopy and confocal microscopy. The defective mitophagy observed in our study was caused by impaired lysosomal function, including mitophagosome-lysosome fusion, lysosome generation, and acidification, resulting in the accumulation of damaged mitochondria in microglial cells. Further analysis revealed that pharmacological blocking or gene-silencing of mitophagy inhibited CKLF-mediated microglial activation, as evidenced by the expression of the microglial marker AIF1 (allograft inflammatory factor 1) and the mRNA of proinflammatory cytokines (Tnf and Il6). Ultimately, defective mitophagy induced by CKLF results in microglial activation, as observed in the brains of adult mice. In summary, CKLF induces defective mitophagy, microglial activation, and inflammation, providing a potential approach for treating neuroinflammatory diseases.Abbreviation: 3-MA: 3-methyladenine; AIF1: allograft inflammatory factor 1; ANOVA: analysis of variance; BAF: bafilomycin A1; BSA: bovine serum albumin; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; cGAMP: cyclic GMP-AMP; CGAS: cyclic GMP-AMP synthase; CKLF/CKLF1: chemokine-like factor 1; CNS: central nervous system; DMEM: Dulbecco's Modified Eagle Medium; DNM1L: dynamin 1 like; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescence protein; IRF3: interferon regulatory factor 3; IgG: immunoglobulin G; LAMP1: lysosomal-associated membrane protein 1; LAPTM4A: lysosomal-associated protein transmembrane 4A; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; Mdivi-1: mitochondrial division inhibitor 1; mRFP: monomeric red fluorescent protein; mtDNA: mitochondrial DNA; MTORC1: mechanistic target of rapamycin kinase complex 1; OPTN: optineurin; PBS: phosphate-buffered saline; PCR: polymerase chain reaction; PINK1: PTEN induced putative kinase 1; PLL: poly-L-lysine; PRKN: parkin RBR E3 ubiquitin protein ligase; qPCR: quantitative polymerase chain reaction; ROS: reactive oxygen species; SQSTM1: sequestosome 1; TBK1: TANK-binding kinase 1; TFEB: transcription factor EB; VDAC: voltage-dependent anion channel.

Regulation of oxygen-glucose deprivation/reperfusion-induced inflammatory responses and M1-M2 phenotype switch of BV2 microglia by lobetyolin

To elucidate the protective mechanism of lobetyolin on oxygen-glucose deprivation/reperfusion (OGD/R)-induced damage in BV2 microglial cells. The OGD/R model was established using a chemical modeling method to simulate in vivo brain ischemia in lobetyolin-pretreated BV2 cells. The optimum lobetyolin dosage, chemical concentration, and OGD/R modeling duration were screened. The changes in cell morphology were observed, and the levels of immune response-related factors, including tumor necrosis factor-α (TNF-α), interleukin-6, inducible nitric oxide synthase (iNOS), and cluster of differentiation (CD)206, were detected using the enzyme-linked immunosorbent assay. The expression of chemokine-like-factor-1 (CKLF1), hypoxia-inducible factor (HIF)-1α, TNF-α, and CD206, was detected using western blotting. The gene expression of M1 and M2 BV2 phenotype markers was assessed using quantitative polymerase chain reaction (qPCR). The localization of M1 and M2 BV2 markers was detected using immunofluorescence analysis. The results showed that lobetyolin could protect BV2 cells from OGD/R-induced damage. After OGD/R, CKLF1/C-C chemokine receptor type 4 (CCR4) levels increased in BV2 cells, whereas the CKLF1/CCR4 level was decreased due to lobetyolin pretreatment. Additionally, BV2 cells injured with OGD/R tended to be M1 type, but lobetyolin treatment shifted the phenotype of BV2 cells from M1 type to M2 type. Lobetyolin decreased the expression of TNF-α and HIF-1α but increased the expression of transforming growth factor-β (TGF-β) in BV2 cells, indicating a dose-effect relationship. The qPCR results showed that lobetyolin decreased the expression of CD16, CD32, and iNOS at the gene level and increased the expression of C-C-chemokine ligand-22 and TGF-β. The immunofluorescence analysis showed that lobetyolin decreased CD16/CD32 levels and increased CD206 levels. Lobetyolin can protect BV2 cells from OGD/R-induced damage by regulating the phenotypic polarization of BV2 and decreasing inflammatory responses. Additionally, CKLF1/CCR4 may participate in regulating lobetyolin-induced polarization of BV2 cells via the HIF-1α pathway.

Spatial and temporal mapping of neuron-microglia interaction modes in acute ischemic stroke

Ischemic stroke (IS) is a major cause of morbidity and mortality worldwide, accounting for 75-80% of all strokes. Under conditions of ischemia and hypoxia, neurons suffer damage or death, leading to a series of secondary immune reactions. Microglia, the earliest activated immune cells, can exert neurotoxic or neuroprotective effects on neurons through secretion of factors. There exists a complex interaction between neurons and microglia during this process. Moreover, the interaction between them becomes even more complex due to differences in the infarct area and reperfusion time. This review first elaborates on the differences in neuronal death modes between the ischemic core and penumbra, and then introduces the differences in microglial markers across different infarct areas with varying reperfusion time, indicating distinct functions. Finally, we focus on exploring the interaction modes between neurons and microglia in order to precisely target beneficial interactions and inhibit harmful ones, thus providing new therapeutic strategies for the treatment of IS.

Determining the chemical profile of Caragana jubata (Pall.) Poir. by UPLC-QTOF-MS analysis and evaluating its anti-ischemic stroke effects

ETHNOPHARMACOLOGICAL RELEVANCE

Caragana jubata, belonging to the Leguminosae family, is a shrubby medicinal plant distributed in high-altitude areas of China. The red heartwood of C. jubata is the original source of 'zuomuxing', a Tibetan medicine that promotes blood circulation and removes blood stasis to treat different diseases associated with the blood.

AIM OF THE STUDY

To date, research on the chemical constituents of C. jubata remains very limited. The anti-ischemic stroke (anti-IS) effects of this plant have not been studied. The aim of the present study was to analyze the chemical profile of C. jubata, establish various anti-IS models to comprehensively evaluate the anti-IS effects of C. jubata, and explore the mechanism of action.

MATERIALS AND METHODS

Ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) was chosen to analyze the chemical profile. A middle cerebral artery occlusion reperfusion (MCAO/R) model, zebrafish cerebral thrombosis model, and oxygen-glucose deprivation/reperfusion (OGD/R) model in PC12/BV2 cells were used to thoroughly evaluate the anti-IS effects of C. jubata. Additionally, western blotting and immunofluorescence staining were used to detect the mechanism of action.

RESULTS

Fifty-three compounds were identified from a 95% ethanol extract of C. jubata (ECJ) by UPLC-QTOF-MS analysis. 17 and 7 compounds were identified from C. jubata and the genus Caragana for the first time. ECJ was found to attenuate infarct size and reduce brain edema and neurological scores in MCAO/R rats. ECJ notably reduced the zebrafish cerebral thrombosis incidence in a dose-dependent manner compared with that in the model group. Surprisingly, compared to the positive control drug aspirin, 50 μg/ml ECJ exhibited a better therapeutic effect than aspirin at 30 μg/ml. Additionally, ECJ significantly increased the viability of PC12/BV2 cells injured by OGD/R. Moreover, ECJ inhibited the protein expression of M1 markers (TNF-α, iNOS, and IL-1β) and increased that of M2 markers (Arg-1 and CD206) in OGD/R-injured BV2 cells. ECJ significantly decreased the immunofluorescence intensity of CD16 and increased that of CD206.

CONCLUSIONS

The results from UPLC-QTOF-MS analysis showed that ECJ was rich in flavonoids. The results from pharmacological experiments verified the anti-IS effects of C. jubata in vivo and in vitro for the first time. In addition, ECJ could regulate the polarization of microglia. The present study highlights the medicinal value of C. jubata, thus providing a theoretical basis for the further development of new drugs from C. jubata to treat IS.

Role of chemokine-like factor 1 as an inflammatory marker in diseases

Immunoinflammatory mechanisms have been incrementally found to be involved in the pathogenesis of multiple diseases, with chemokines being the main drivers of immune cell infiltration in the inflammatory response. Chemokine-like factor 1 (CKLF1), a novel chemokine, is highly expressed in the human peripheral blood leukocytes and exerts broad-spectrum chemotactic and pro-proliferative effects by activating multiple downstream signaling pathways upon binding to its functional receptors. Furthermore, the relationship between CKLF1 overexpression and various systemic diseases has been demonstrated in both in vivo and in vitro experiments. In this context, it is promising that clarifying the downstream mechanism of CKLF1 and identifying its upstream regulatory sites can yield new strategies for targeted therapeutics of immunoinflammatory diseases.

Resveratrol Inhibits Oxidative Stress and Regulates M1/M2-Type Polarization of Microglia via Mediation of the Nrf2/Shh Signaling Cascade after OGD/R Injury In Vitro

AIMS

Microglia are closely related to the occurrence and development of oxidative stress. Cerebral ischemia leads to abnormal activation of microglia. Resveratrol can regulate M1/M2-type microglia polarization, but the underlying mechanism is not well understood, although the Nrf2 and Shh signaling pathways may be involved. Given that resveratrol activates Shh, the present study examined whether this is mediated by Nrf2 signaling.

METHODS

N9 microglia were pretreated with drugs before oxygen-glucose deprivation/reoxygenation (OGD/R). HT22 neurons were also used for conditional co-culture with microglia. Cell viability was measured by CCK-8 assay. MDA levels and SOD activity in the supernatant were detected by TBA and WST-1, respectively. Immunofluorescence detected Nrf2 and Gli1 nuclear translocation. The levels of CD206, Arg1, iNOS, TNF-α, Nrf2, HO-1, NQO1, Shh, Ptc, Smo, Gli1 protein and mRNA were measured by Western blotting or RT-qPCR. Annexin V-FITC Flow Cytometric Analysis detected apoptosis.

RESULTS

Resveratrol and Nrf2 activator RTA-408 enhanced the viability of microglia, reduced oxidative stress, promoted M2-type microglia polarization and activated Nrf2 and Shh signaling. ML385, a selective inhibitor of Nrf2, decreased the viability of microglia, aggravated oxidative stress, promoted M1-type microglia polarization and inhibited Nrf2 and Shh signaling. Moreover, resveratrol and RTA-408-treated microglia can reduce the apoptosis and increase the viability of HT22 neurons, while ML385-treated microglia aggravated the apoptosis and weakened the viability of HT22 neurons.

CONCLUSIONS

These results demonstrated that resveratrol may inhibit oxidative stress, regulate M1/M2-type polarization of microglia and decrease neuronal injury in conditional co-culture of neurons and microglia via the mediation of the Nrf2/Shh signaling cascade after OGD/R injury in vitro.

Neuronal chemokine-like-factor 1 (CKLF1) up-regulation promotes M1 polarization of microglia in rat brain after stroke

The phenotypic transformation of microglia in the ischemic penumbra determines the outcomes of ischemic stroke. Our previous study has shown that chemokine-like-factor 1 (CKLF1) promotes M1-type polarization of microglia. In this study, we investigated the cellular source and transcriptional regulation of CKLF1, as well as the biological function of CKLF1 in ischemic penumbra of rat brain. We showed that CKLF1 was significantly up-regulated in cultured rat cortical neurons subjected to oxygen-glucose deprivation/reoxygenation (ODG/R) injury, but not in cultured rat microglia, astrocytes and oligodendrocytes. In a rat model of middle cerebral artery occlusion, we found that CKLF1 was up-regulated and co-localized with neurons in ischemic penumbra. Furthermore, the up-regulated CKLF1 was accompanied by the enhanced nuclear accumulation of NF-κB. The transcriptional activity of CKLF1 was improved by overexpression of NF-κB in HEK293T cells, whereas application of NF-κB inhibitor Bay 11-7082 (1 μM) abolished it, caused by OGD/R. By using chromatin-immunoprecipitation (ChIP) assay we demonstrated that NF-κB directly bound to the promoter of CKLF1 (at a binding site located at -249 bp to -239 bp of CKLF1 promoter region), and regulated the transcription of human CKLF1. Moreover, neuronal conditional medium collected after OGD/R injury or CKLF1-C27 (a peptide obtained from secreted CKLF1) induced the M1-type polarization of microglia, whereas the CKLF1-neutralizing antibody (αCKLF1) or NF-κB inhibitor Bay 11-7082 abolished the M1-type polarization of microglia. Specific knockout of neuronal CKLF1 in ischemic penumbra attenuated neuronal impairments and M1-type polarization of microglia caused by ischemic/reperfusion injury, evidenced by inhibited levels of M1 marker CD16/32 and increased expression of M2 marker CD206. Application of CKLF1-C27 (200 nM) promoted the phosphorylation of p38 and JNK in microglia, whereas specific depletion of neuronal CKLF1 in ischemic penumbra abolished ischemic/reperfusion-induced p38 and JNK phosphorylation. In summary, CKLF1 up-regulation in neurons regulated by NF-κB is one of the crucial mechanisms to promote M1-type polarization of microglia in ischemic penumbra.

Lipoxin A4 regulates microglial M1/M2 polarization after cerebral ischemia-reperfusion injury via the Notch signaling pathway

Microglia are rapidly activated after acute ischemic stroke, and the polarization of microglial is associated with the prognosis of acute ischemic stroke. Lipoxin A4 (LXA4), an anti-inflammatory agent, has a protective effect against ischemic stroke. However, the role of LXA4 on the polarization of microglial after acute ischemic stroke remains undetermined. We hypothesized that LXA4 may exert the neuroprotective effect though regulating the polarization of microglial. In this study, clinical features of acute ischemic stroke were simulated using a rat model of model of middle cerebral artery occlusion (MCAO) in vivo and the BV2 microglia oxygen-glucose deprivation/reoxygenation model (OGD/R) in vitro. The protective effects of LXA4 on cerebral ischemia-reperfusion injury were determined using TTC staining, HE staining, and TUNEL staining. The expression of targeted genes was assayed using quantitative real-time PCR (qRT-PCR), immunofluorescence, and western blot to investigated the regulation of LXA4 on microglia polarization after acute ischemic stroke. We found that LXA4 exerted protective effects on focal cerebral ischemia-reperfusion injury and reduced the expression of the pro-inflammatory cytokines IL-1β and TNF-α. Furthermore, LXA4 inhibited the expression of Notch-1, Hes1, iNOS and CD32 all of which are associated with the differentiation into M1 microglia. By contrast, LXA4 upregulated the expression of Hes5, Arg-1 and CD206 all of which are associated with M2 phenotype in microglia. In addition, blocking the Notch signaling pathway with the inhibitor DAPT significantly mitigated the effect of LXA4 on microglia differentiation. These data suggest that LXA4 may regulate the polarization of microglia after cerebral ischemia-reperfusion injury through the Notch signaling pathway.

Kanglaite enhances the efficacy of cisplatin in suppression of hepatocellular carcinoma via inhibiting CKLF1 mediated NF-κB pathway and regulating transporter mediated drug efflux

ETHNOPHARMACOLOGICAL RELEVANCE

Kanglaite (KLT) is an active extract of the Coix lacryma-jobi seed, which can benefit Qi and nourish Yin, and disperse the accumulation of evils. It is used as a biphasic broad-spectrum anti-cancer drug, and shows synergistic effects with radiotherapy and chemotherapy. However, the mechanism of KLT combined with cisplatin (CDDP) against hepatocellular carcinoma (HCC) has not been elucidated.

AIM OF THE STUDY

The aim of present study was to investigate the potential synergistic effects of KLT and CDDP on HepG2 cells, discussing the possible mechanisms from the perspective of CKLF1 and NF-κB mediated inflammatory response and chemoresistance, and the involvement of drug efflux transporters.

MATERIALS AND METHODS

CDDP injured HepG2 cells were used to investigate the effects of KLT on chemotherapeutics treated HCC. Effects of KLT pretreatment on CDDP injured HepG2 cells were determined by MTT, wound healing assay, and transwell assay. Expression of chemokine-like factor 1 (CKLF1) and activation of nuclear factor κB (NF-κB) were examined by qPCR, western blot, and immunofluorescence staining. Furthermore, to study the role of CKLF1 in KLT mediated effects on this CDDP injured HCC cell model, HepG2 cells overexpressed with CKLF1 gene were used. Cell viability and NF-κB activation were investigated. Moreover, TNF-α and IL-1β levels were measured by Elisa analysis and western blot to evaluate the inflammatory response. Additionally, ATP-binding cassette (ABC) drug efflux transporters, MDR1, MRP2, and BCRP were also determined in present study.

RESULTS

KLT pretreatment followed by CDDP treatment was found to show synergistic effects, which showed by decreased cell viability, migration and invasion ability of HepG2 cells. Expression of CKLF1 enhanced significantly in CDDP treated HepG2 cells, and KLT decreased this elevation obviously. Furthermore, CDDP activated NF-κΒ and promoted translocation of NF-κB toward the nucleus. KLT inhibited the activation of NF-κΒ, which sensitized cancer cells. Overexpression of CKLF1 reversed the effects of KLT on CDDP injured HepG2 cells, which exhibited by increased cell viability and enhanced activation of NF-κΒ. CDDP induced NF-κΒ activation could also lead to excessive inflammatory response, and KLT can suppress the aggravating inflammation which may be beneficial for tumor progression. Furthermore, we found that ABC drug efflux transporters MDR1, MRP2, and BCRP in CDDP treated HepG2 cells were decreased when pretreated with KLT.

CONCLUSIONS

KLT pretreatment may increase the effects of CDDP on HepG2 cells, by exhibiting cooperative effects on suppression of HepG2 cells. The mechanisms may partly by inhibiting CKLF1 mediated NF-κB pathway, which may contribute to inflammation of tumor microenvironment and chemoresistance of CDDP. Inhibition of transporter-mediated drug efflux is also involved in KLT mediated sensitization effects of CDDP.

Salvianolate reduces neuronal apoptosis by suppressing OGD-induced microglial activation

AIMS

The aim of this study was to investigate the mechanism of pro-inflammatory phenotype transformation of microglia induced by oxygen-glucose deprivation (OGD), and how salvianolate regulates the polarization of microglia to exert neuroprotective effects.

MAIN METHODS

The immunofluorescence and western blot experiments were used to verify the injury effect on neuronal cells after inflammatory polarization of microglia. Secondly, immunofluorescence staining and western blot were analyzed inflammatory phenotype of microglia and TLR4 signaling pathway after salvianolate treatment. RT-qPCR and ELISA assays were showed the levels of RNA and proteins of inflammatory factors in microglia. Finally, flow cytometry and western blot assay proved that salvianolate had a certain protective effect on neuronal injury after inhibiting the phenotype of microglia.

KEY FINDINGS

The OGD condition could promote inflammation and activate of TLR4 signal pathway in microglia, and the polarization of microglia triggered caspase-3 signal pathway of neuronal cell. The optimal concentrations of salvianolate were incubated with microglia under OGD condition, which could reduce the reactive oxygen species (ROS) expression (P = 0.002) and also regulate the activity of SOD, CAT and GSH-px enzymes (P < 0.05). Moreover, salvianolate treatment could inhibit TLR4 signal pathway (P = 0.012), suppress the pro-inflammatory phenotype of microglia in OGD condition (P = 0.018), and reduce the expression of IL-6 and TNF-α (P < 0.05). Finally, neuronal damage induced by microglia under OGD condition was reversed after administration of the microglia supernatant after salvianolate treatment.

SIGNIFICANCE

Salvianolate, as an antioxidant, plays a neuroprotective role by inhibiting the pro-inflammatory phenotype and decreasing the expression of ROS in microglia.

Polysaccharide from Schisandra chinensis acts via LRP-1 to reverse microglia activation through suppression of the NF-κB and MAPK signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (Turcz.) Baill (S. Chinensis), a traditional Chinese medicine frequently used in the traditional treatment of dementia, its polysaccharide component has been widely reported.

AIM OF THE STUDY

In this paper, we studied whether SCP2-1, a natural product of homogeneous polysaccharide from S. Chinensis, could improve M1 and M2 polarization and inhibit neuroinflammation through lipoprotein receptor-related protein-1 (LRP-1), and futher exerted anti-inflammatory and neuroprotective effects.

MATERIALS AND METHODS

SCP2-1 was obtained from crude polysaccharide of S. Chinensis, BV2 microglia cells and mice stimulated by LPS were served to detect the positive role of SCP2-1 in M1/M2 polarization. The concentration of cytokine expression, IL-1β, TNF-α, IL-12 and IL-6 for M1 polarization and TGF-β, IL-10, IL-4 and Arg-1 for M2 polarization, in the BV2 and hippocampus were tested by ELISA kits. CD86 and CD206, as surface markers of M1 and M2, were tested by flow cytometry. We examined the expression of LRP-1 in BV2 cells and mouse hippocampus. The addition of siRNA for LRP-1 demonstrated the important role of LRP-1 in the neuroprotection of SCP2-1. Western blot was used to detect the activation of various mitogen-activated protein kinase (MAPKs) pathway, i.e. the phosphorylation of JNK and ERK proteins, and nuclear translocation of nuclear factor κB (NF-κB). H.E. staining was used to observe Histopathological changes.

RESULTS

SCP2-1 could reverse M1/M2 polarization in vitro culture and suppressed M1 polarization in the hippocampus of mice stimulated with LPS. After LPS stimulation, poor levels of LRP-1, hyperactivation of the JNK and NF-κB was appeared, which could improve by SCP2-1. The addition of siRNA for LRP-1 suppressed the protection of SCP2-1 in BV2 microglial cells. More importantly, SCP2-1 could improve LPS-induced cognitive dysfunction in mice in Y-maze and NOR test.

CONCLUSIONS

SCP2-1 could improve M1/M2 polarization, especially inhibit M1 polarization, and ameliorate the cognition of mice in Y-maze and NOR test. SCP2-1 play a neuroprotective role through LRP-1 to reverse activation of microglia via suppressing the overactive NF-κB and JNK pathway.

Modulators of microglia activation and polarization in ischemic stroke (Review)

Ischemic stroke is one of the leading causes of mortality and disability worldwide. However, there is a current lack of effective therapies available. As the resident macrophages of the brain, microglia can monitor the microenvironment and initiate immune responses. In response to various brain injuries, such as ischemic stroke, microglia are activated and polarized into the proinflammatory M1 phenotype or the anti-inflammatory M2 phenotype. The immunomodulatory molecules, such as cytokines and chemokines, generated by these microglia are closely associated with secondary brain damage or repair, respectively, following ischemic stroke. It has been shown that M1 microglia promote secondary brain damage, whilst M2 microglia facilitate recovery following stroke. In addition, autophagy is also reportedly involved in the pathology of ischemic stroke through regulating the activation and function of microglia. Therefore, this review aimed to provide a comprehensive overview of microglia activation, their functions and changes, and the modulators of these processes, including transcription factors, membrane receptors, ion channel proteins and genes, in ischemic stroke. The effects of autophagy on microglia polarization in ischemic stroke were also reviewed. Finally, future research areas of ischemic stroke and the implications of the current knowledge for the development of novel therapeutics for ischemic stroke were identified.