Heixiaoyao Powder interferes with microglia polarization in AD model mice by regulating NOX2/ROS/NF-κB signaling pathway / 中国中药杂志

The effect and mechanism of Heixiaoyao Powder on the polarization of microglia(MG) in APP/PS1 double transgenic mice were explored based on NADPH oxidase 2(NOX2)/reactive oxygen species(ROS)/nuclear factor kappaB(NF-κB) signaling pathway. Fifty 4-month-old male APP/PS1 mice were randomly divided into a model group, an MCC950 group(10 mg·kg~(-1)), and low-, medium-, and high-dose Heixiaoyao Powder groups(6.45, 12.89, and 25.78 g·kg~(-1)). Thirty male C57BL/6J mice of the same age and strain were randomly divided into a blank group, a blank + intragastric intervention group, and a blank + intraperitoneal injection group. Drug intervention lasted 90 days. Morris water maze test was used to detect learning and cognitive ability. Nissl staining and transmission electron microscopy were used to observe the pathological morphology and ultrastructure of hippocampal neurons. Immunofluorescence was used to detect the positive expression of M1-type marker CD16/32~+/Iba-1~+, M2-type marker CD206~+/Iba-1~+ of MG and the expression of hippocampal ROS. The colorimetric method was used to detect the content of malondialdehyde(MDA) and superoxide dismutase(SOD) in the hippocampus. Enzyme linked immunosorbent assay(ELISA) was used to detect the levels of inflammatory factors, including interleukin-6(IL-6), interleukin-8(IL-8), and tumor necrosis factor-α(TNF-α), in the hippocampus. Western blot was used to detect the protein expression of β-amyloid protein(Aβ), Iba-1, CD16/32, CD206, NOX2, NF-κB, p-NF-κB, NF-κB inhibitor alpha(IκBα), and p-IKBα in the hippocampus. The results showed that as compared with the blank group, the model group showed prolonged target quadrant movement distance and escape latency(P<0.01), shortened target quadrant retention time and percentage(P<0.01), disorganized neuronal cells with swelling, nuclear disappearance or bias, reduced number of cells, dissolved or absent Nissl bodies, and a clear area in the cytoplasm, damaged and shrunk cell membrane with abnormal cell morphology, few organelles in the cytoplasm, reduced and swollen mitochondria, increased MG M1-type marker CD16/32~+/Iba-1~+(P<0.01), decreased M2-type marker CD206~+/Iba-1~+(P<0.01), increased ROS activity and MDA content(P<0.01), decreased SOD level(P<0.01), elevated inflammatory factors IL-6, IL-8, and TNF-α(P<0.01), up-regulated protein expression and phosphorylation of Aβ, CD16/32, Iba-1, NOX2, NF-κB, and IKBα(P<0.01), and down-regulated CD206(P<0.01). There was no statistically significant difference between the blank group, the blank + intragastric intervention group, and the blank + intraperitoneal injection group. After the intervention of Heixiaoyao Powder, the Heixiaoyao Powder groups showed shortened target quadrant movement distance and escape latency(P<0.01), prolonged target quadrant retention time and percentage(P<0.01), increased and neatly arranged cells with relieved swelling, increased Nissl bodies, regular cell morphology, and intact cell membrane, relieved swelling of mitochondria, slightly expanded endoplasmic reticulum, decreased CD16/32~+/Iba-1~+(P<0.05 or P<0.01), increased CD206~+/Iba-1~+(P<0.01), decreased ROS activity and MDA content(P<0.01), increased SOD level(P<0.01), decreased content of inflammatory factors IL-6, IL-8, and TNF-α(P<0.01), down-regulated protein expression and phosphorylation of Aβ, CD16/32, Iba-1, NOX2, NF-κB, and IKBα(P<0.01), and up-regulated CD206(P<0.01). In conclusion, Heixiaoyao Powder can alleviate neuronal damage and improve the learning and memory abilities of APP/PS1 mice. The mechanism of action may be related to the inhibition of NOX2/ROS/NF-κB signaling pathway, regulating the polarization of MG, increasing the expression of M2 type, inhibiting the expression of M1 type, and reducing the release of inflammatory factor.

Dexmedetomidine attenuates neuroinflammation by inhibiting NF-κB nuclear translocation in rats with traumatic brain injury / 中华急诊医学杂志

Objective:To explore the mechanism of dexmedetomidine (DEX) regulating microglial (MG) polarization and neuroinflammation after traumatic brain injury (TBI) in rats.Methods:Forty-two adult male SD rats were randomly (random number) divided into the sham group, TBI group, TBI+DEX group (further divided into 1 d, 3 d and 7 d subgroups), TBI+NF-κB inhibitor (pyrrolidine dithiocarbamate, PDTC) group and TBI+DEX+PDTC group, with 6 animals in each group. The rat TBI model was established according to the modified Feeney free fall method. PDTC was intraperitoneally injected 1 h after modeling with a dose of 100 mg/kg, and DEX was intraperitoneally injected 2 h after modeling with a dose of 100 μg/kg. Modified neurological severity score (mNSS) was used to evaluate rat neurological function, ELISA was used to detect serum inflammatory factors, and rats’ damaged cortex was collected to detect the phenotype markers of MG and protein expressions of MyD88 and NF-κB p65, and immunofluorescence staining was used to observe the expression and nuclear entry of NF-κB p65 in MG in injured cortex. One-way and two-way ANOVA were used to compare the measurement data among multiple groups.Results:Compared with the sham group, the mNSS score was significantly higher in the TBI group, and DEX treatment significantly decreased the mNSS score of TBI rats ( P<0.05). ELISA and Western blot results showed that in the TBI group, the tumor necrosis factor-α (TNF-α), interleukin (IL)-1β in serum and M1 phenotype marker (TNF-α, IL-1β) in brain were increased, the expression of anti-inflammatory factor IL-10 in serum and M2 phenotype markers (arginase-1 and IL-10) in brain were decreased ( P<0.05), and DEX downregulated the expression of TNF-α, IL-1β in serum and M1 phenotype markers in brain, while upregulated the level of L-10 in serum and the M2 phenotype marker in brain ( P<0.05). In addition, the expression of MyD88 and the nuclear translocation of NF-κB p65 were inhibited in the DEX group, and this effect could be enhanced by PDTC. Conclusions:DEX modulates MG activation in TBI rats by inhibiting NF-κB nuclear translocation and reduces neuroinflammation.

Effects of butyphthalide on microglia polarization after intracerebral hemorrhage and the underlying mechanisms / 中南大学学报(医学版)

OBJECTIVES@#Because intracerebral hemorrhage (ICH) has high morbidity, disability and mortality, it is significant to find new and effective treatments for ICH. This study aims to explore the effect of butyphthalide (NBP) on neuroinflammation secondary to ICH and microglia polarization.@*METHODS@#A total of 48 healthy male SD rats were randomly divided into 6 groups: a sham 24 h group, a sham 72 h group, an ICH 24 h group, an ICH 72 h group, an ICH+NBP 24 h group, and an ICH+NBP 72 h group (8 rats per group). After operation, the neurological deficiencies were assessed based on improved Garcia scores and corner test. The expressions of Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), aquaporin-4 (AQP4), zonula occludens-1 (ZO-1), occludin, CD68, CD86, and CD206 were observed by Western blotting. Inflammatory cytokines were detected by ELISA. The immunofluorescence was to detect the polarization of microglia.@*RESULTS@#1) Compared with the sham groups, the expression of TLR4 (24 h: P<0.05; 72 h: P<0.01), NF-κB (both P<0.01) and Nrf2 (both P<0.01) in the perihematoma of the ICH group was increased, leading to microglia activation (P<0.01). The expressions of IL-6 (24 h: P<0.05; 72 h: P<0.01) and TNF-α (both P<0.01), the pro-inflammatory cytokines were up-regulated, and the expression of anti-inflammatory cytokine IL-4 was down-regulated (both P<0.01). Besides, the expression of AQP4 was enhanced (both P<0.01). The protein level of tightly connected proteins (including ZO-1, occludin) was decreased (all P<0.01). The neurological function of the rats in the ICH group was impaired in the 2 time points (both P<0.01). 2) Compared with the sham group at 24 h and 72 h after the intervention of NBP, the expressions of TLR4 (both P<0.05) and NF-κB (both P<0.01) were significantly declined, and the expression of Nrf2 was further enhanced (both P<0.05) in the perihematoma of the ICH+NBP group. Furthermore, the expression of M1 microglia marker was inhibited (P<0.05), and the polarization of microglia to the M2 phenotype was promoted (P<0.01). 3) In terms of inflammation after ICH, the IL-4 expression in the ICH+NBP group was increased compared with the ICH group (24 h: P<0.05; 72 h: P<0.01); the expression of IL-6 was decreased significantly in the ICH+NBP 72 h group (P<0.01); the level of AQP4 was declined significantly in the ICH+NBP 24 h group (P<0.05), there was a downward trend in the 72-hour intervention group but without significant statistical difference. 4) Compared with the ICH group, the ZO-1 protein levels were increased (24 h: P<0.05; 72 h: P<0.01), and the symptoms of nerve defect were improved eventually (both P<0.05) in the ICH+NBP groups.@*CONCLUSIONS@#After ICH, the TLR4/NF-κB pathway is activated. The M1 microglia is up-regulated along with the release of detrimental cytokines, while the anti-inflammatory cytokines are down-regulated. The expression of AQP4 is increased, the tight junction proteins from the blood-brain barrier (BBB) is damaged, and the neurological function of rats is impaired. On the contrary, NBP may regulate microglia polarization to M2 phenotype and play a role in the neuroprotective effect mediated via inhibiting TLR4/NF-κB and enhancing Nrf2 pathways, which relieves the neuroinflammation, inhibits the expression of AQP4, repairs BBB, and improves neurological functional defects.

The mechanism by which epidermal growth factor 8 regulates microglia polarization in transient cerebral ischemia / 中华物理医学与康复杂志

Objective:To explore the function of epidermal growth factor 8 in the polarization of microglia after ischemic brain injury and its mechanism.Methods:Forty C57BL/6 mice were randomly divided into a sham operation group, an ischemia group, a recombinant mouse milk fat globule epidermal growth factor 8 (rmMFG-E8) group and an rmMFG-E8 + colivelin TFA group, each of 10. The middle cerebral artery occlusion and reperfusion model (tMCAO) was established in all except the sham operation group. Right after the modelling the mice in the rmMFG-E8 group were immediately injected with 2μL of 0.4μg/μL of rmMFG-E8 into the ventricle contralateral to the cerebral infarction. The rmMFG-E8+ Colivelin TFA group was injected with the same dose of rmMFG-E8 plus 2μL of 5pmol/μL colivelin TFA. On the 1st, 3rd, 5th and 7th day after the modelling, neurological functioning was documented using behavioral tests. The volume proportion of the cerebral infarction was observed after tissue staining on the 7th day after the operation. The gene expression levels of M1 polarization marker-induced nitric oxide synthase (iNOS), M2 polarization marker arginase-1 (Arg1) and mouse chitinase-like molecule 3 (YM1) in the microglia were detected using real-time fluorescence quantitative polymerase chain reactions. The protein expression levels of MFG-E8, phosphorylated signal transduction and transcription factor 3 (p-STAT3) and cytokine signal transduction inhibitor-3 (SOCS3) were determined using western blotting.Results:The behavior tests revealed significant differences between the sham operation group and the other groups on all four days. Compared with the sham operation group, the average expression of MFG-E8 gene and its protein, Arg1 and Ym1, and the SOCS3/GAPDH protein ratio had decreased significantly in the ischemic group, while the average expression of iNOS and the p-STAT3/STAT3 protein ratio had increased significantly. On the 7th day after the modelling, compared with the ischemic group, the infarct volume was significantly smaller in the rmMFG-E8 group. The average expression of iNOS and the average p-STAT3/STAT3 ratio in the rmMFG-E8+ colivelin TFA group had increased significantly compared with the rmMFG-E8 group, while the average expression of Arg1 and Ym1, and the SOCS3/GAPDH ratio were significantly lower.Conclusion:MFG-E8 promotes the polarization of M2-type microglia after cerebral ischemia through STAT3 signaling, promoting the recovery of neurological functioning.

Promotion of Analgecine on Polarization of M1 Microglia to M2 and Inhibition on Secretion of Inflammatory Factors in Vitro / 中国康复理论与实践

Objective:To investigate the effect of analgecine (AGC) on inflammatory response in the cell model of ischemic stroke and its mechanism. Methods:Sodium hydrosulfite (Na2S2O2) combined with sugar-free culture-medium was used to stimulate the model of ischemic stroke in vitro. BV2 cells were divided into six groups: control group, control with 0.5 U/ml AGC group, oxygen deprivation and recovery (OGD/R) group, OGD/R with AGC (0.25 U/ml, 0.5 U/ml, 1 U/ml) groups. After oxygen and glucose deprivation for 1.5 hours, they were changed to normal medium and given different concentrations of AGC in OGD/R with AGC groups. After co-incubation for three hours, the cells were treated. The content of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the supernatant was detected. The expression of M1-type microglia marker CD16+CD32 and M2-type microglia marker CD206 were detected with immunofluorescent staining. BV2 cells were divided into seven groups: control group, control with 0.5 U/ml AGC group, IL-4 group, IL-4 + lipopolysaccharide (LPS) + interferon (IFN)-γ group, IL-4 + LPS + IFN-γ with AGC (0.25 U/ml, 0.5 U/ml, 1 U/ml) groups. After 24 hours of IL-4 treatment, LPS + IFN-γ were added for 18 hours, they were changed to normal medium and given different concentrations of AGC for 24 hours, the expression of CD16+CD32 and CD206 were observed by flow cytometry. Results:Compared with the control group, the IL-6 and TNF-α level increased (P < 0.01), the number of CD16++CD32+ increased and the number of CD206+ decreased in OGD/R group. Compared with the OGD/R group, the IL-6 and TNF-α level decreased (P < 0.01), the number of CD16++CD32+ decreased and the number of CD206+ increased in AGC groups. Compared with the control group, the number of CD206 tended to increase, and the number of CD16+CD32 tended to decrease in IL-4 group; compared with IL-4 group, the number of CD16+CD32 tended to increase, and the number of CD206 tended to decrease in IL-4 + LPS + IFN-γ group; compared with IL-4 + LPS + IFN-γ group, the number of CD16+CD32 tended to decrease, and the number of CD206 tended to increase in IL-4 + LPS + IFN-γ + 0.25 U/ml AGC group and IL-4 + LPS + IFN-γ + 0.5 U/ml AGC group, while the number of CD206 increased in IL-4 + LPS + IFN-γ + 1.0 U/ml AGC group (P < 0.05). Conclusion:AGC could inhibit the secretion of inflammation factors by promoting the polarization of microglia from M1 phenotype to M2 phenotype.

Expression of repulsive guidance molecule a in polarized microglia after rat focal cerebral ischemia/reperfusion injury / 解剖学报

Objective: To investigate the expression of repulsive guidance molecule A (RGMa) in polarized microglia after rat focal cerebral ischemia/reperfusion injury. Methods: Adult male Sprague-Dawley (SD) rats were randomly divided into control group, 7 days cerebral ischemia/reperfusion injury group (I/R), and 14 days I/R group. The transient middle cerebral occlusion (tMCAO) model was induced by ligation with nylon monofilament. Real-time PCR was used to test the mRNA expression of Ml and M2 microglia marker interleukin-1Î2 (IL-1Î2), inducible nitric oxide synthase (iNOS), arginase 1 (Arg-1) and CD206 in ipsilateral cortex at day 7 and day 14. Double immunofluorescence staining was performed to investigate the co-expression of RGMa and Ibal in microglia. The microglia was incubated with lipopolysaccharides (LPS)or IL-4 in vitro. The mRNA expression of Ml and M2 microglia marker (IL-1Î2, iNOS, Arg-1, CD206) was tested by Real-time PCR. Western blotting was used to assess the proteins level of RGMa in Ml and M2 microglia. Results: M1 and M2 microglia marker mRNA level were increased in ipsilateral cortex at day 7 and day 14. RGMa was strongly expressed in reactive microglia at day 7 and day 14. LPS or IL-4 treatment polarized microglia to Ml or M2 in vitro. The expression of RGMa protein in Ml and M2 microglia was increased. Conclusion: RGMa was strongly expressed in reactive Ml and M2 microglia after ischemia/reperfusion injury. RGMa may play an important role in the process of microglia activation and polarization. RGMa may be a novel therapeutic target for stroke.

Advances in research of the role of microglia polarization in the mechanisms of pathogenesis of multiple sclerosis / 中国比较医学杂志

Multiple sclerosis ( MS) is an autoimmune disease of the central nervous system ( CNS) characterized by demyelination and inflammation lesions.MS predominantly affects young adults with a high incidence of disability. However, the exact pathogenesis of MS is still not clear.Studies found that microglia polarization tending to pro-inflammatory M1-like state during the onset of MS, causing the M1/M2 ratio imbalance, forming pro-inflammatory microenvironment state, and which further leading to nervous tissue damage ultimately.Microglia polarization may be considered as the initiator of pathologic alterations by releasing pro-inflammatory cytokines and secondarily trigger the initial microglia response.Given the pivotal role of imbalanced microglia polarization in MS initiation, a critical review of microglia polarization is presented here, in order to elucidate the pathogenesis of MS and highlight the noteworthy candidate therapeutic targets for clinic treatment.