Excessive microglial activation and subsequent neuroinflammation lead to neuronal cell death, which are involved in the pathogenesis and progression of several neurodegenerative diseases such as Parkinson's disease. The objective of this study was to determine the involvement of chlorpyrifos (CPF) in the activation of microglia and production of inflammatory factors in response to CPF stimulation and the influence on the viability of dopaminergic (DA) neurons. We detected the change of BV-2 cells morphology and expression of inducible nitric oxide (iNOS), cyclooxygenase-2 (COX-2) mRNA and protein level upon CPF stimulation (0, 1, 3, 6, 12, 24 h) in BV-2 (mouse brain microglia) cells by reverse transcription polymerase chain reaction (RT-PCR) or Western blot. We randomly assigned BV-2 cells into CPF, menstruum dimethysulfoxide (DMSO) and normal saline (NS) groups. We stimulated The BV-2 cells in the CPF group with CPF, and we stimulated the two control groups with DMSO or NS for 12 hours, respectively. We then collected the used culture media from the culture dishes and centrifuged it to remove the detached cells. Then, we used the supernatants as microglial conditioned media. We treated SH-SY5Y neurons with various groups of microglial conditioned media for 24 hours. We observed the effect of conditioned media collected from BV-2 cell on the viability of dopaminergic cell lines SH-SY5Y using MTT assay. We found that inflammatory factors iNOS, COX-2 mRNA and protein levels were up-regulated upon CPF stimulation. Conditioned media from BV-2 upon CPF stimulation is toxic to SH-SY5Y. It might be concluded that the exposure to CPF may induce dopaminergic neuronal damage by the activation of inflammatory response, and a mechanism may be involved in Parkinson's disease pathogenesis.
Objective To observe the effect of bone marrow mesenchymal stem cells (BMSCs) conditioned medium on microglia (MGs) and its secretion of arginase 1 (Arg1). Methods The BMSCs separated through differential adhesion method from the femur and tibia marrow of 4-week-old Sprague Dawley (SD) rats were cultured and identified by Vimentin immunofluorescence staining; whereas MGs separated through trypsin digestion method from the brain of 3-day-old SD rats were cultured and identified by Iba1 immunofluorescence staining. The primary MGs were cultured with DMEM/F12 medium containing BMSCs conditioned medium (experimental group) and with single DMEM/F12 medium (control group), respectively. After 48 hours of culture, the morphology of MGs was observed by inverted phase contrast microscope, the activated state of MGs was detected by using Iba1 immunofluorescence staining, and Arg1 expression of MGs was assessed by Iba1-Arg1 double-labelling immunofluorescence staining and Western blot method. Results Inverted phase contrast microscope observation showed that BMSCs entered logarithmic growth phase at 14 days after culture, and more than 98% cells were positive to Vimentin immunofluorescence staining; whereas MGs entered logarithmic growth phase at 21 days after culture, and around 80% cells were positive to Iba1 immunofluorescence staining. Inverted phase contrast microscope observation displayed that in the experimental group, MGs were activated with increased size of soma, shortened process, and amoeba change. Immunofluorescence staining displayed that the Iba1 positive cells number in the experimental group was significantly higher than that in the control group (t=0.007, P=0.000); double-labelling immunofluorescence staining revealed that the Iba1-Arg1 positive cells number in the experimental group was significantly higher than that in the control group (t=0.007, P=0.000); and Western blot results elucidated that the relative expression of Arg1 protein in the experimental group was significantly higher than that in the control group (t=0.001, P=0.000). Conclusion BMSCs conditioned medium can activate MGs and induce MGs to express Arg1.
Postoperative cognitive dysfunction (POCD) is one of the most common complications after surgery under general anesthesia and usually manifests as newly presented cognitive impairment. However, the mechanism of POCD is still unclear. In addition to neurons, glial cells including microglia, astrocytes and oligodendrocytes, represent a large cell population in the nervous system. The bi-directional communication between neurons and glia provides basis for neural circuit function. Recent studies suggest that glial dysfunctions may contribute to the occurrence and progress of POCD. In this paper, we review the relevant work on POCD, which may provide new insights into the mechanism and therapeutic strategy for POCD.
Objective To investigate the effect of M2-like macrophage/microglia-derived mitochondria transplantation in treatment of mouse spinal cord injury (SCI). Methods BV2 cells were classified into M1 (LPS treatment), M2 (IL-4 treatment), and M0 (no treatment) groups. After receiving M1 and M2 polarization, BV2 cells received microscopic observation, immunofluorescence staining [Arginase-1 (Arg-1)] and flow cytometry [inducible nitric oxide synthase (iNOS), Arg-1] to determine the result of polarization. MitoSox Red and 2, 7-dichlorodi-hydrofluorescein diacetate (DCFH-DA) stainings were used to evaluate mitochondrial function difference. Mitochondria was isolated from M2-like BV2 cells through differential velocity centrifugation for following transplantation. Then Western blot was used to measure the expression levels of the relevant complexes (complexes Ⅱ, Ⅲ, Ⅳ, and Ⅴ) in the oxidative phosphorylation (OXPHOS), and compared with M2-like BV2 cells to evaluate whether the mitochondria were obtained. Thirty-six female C57BL/6 mice were randomly divided into 3 groups (n=12). Mice from sham group were only received the T10 laminectomy. After the T10 spinal cord injury (SCI) model was prepared in the SCI group and mitochondria transplantation (MT) group, mitochondrial storage solution and mitochondria (100 μg) derived from M2-like BV2 cells were injected into the injured segment, respectively. After operation, the Basso Mouse Scale (BMS) score was performed to evaluate the motor function recovery. And immunofluorescence staining, lycopersicon esculentum agglutinin (LEA)-FITC staining, and ELISA [vascular endothelial growth factor A (VEGFA)] were also performed. Results After polarization induction, BV2 cells in M1 and M2 groups showed specific morphological changes of M1-like and M2-like macrophages, respectively. Immunofluorescence staining showed that the positive expression of M2-like macrophages marker (Arg-1) was significantly higher in M2 group than in M0 group and M1 group (P<0.05). Flow cytometry showed that the expression of M1-like macrophage marker (iNOS) was significantly higher in M1 group than in M0 group and M2 group (P<0.05), and the expression of Arg-1 was significantly higher in M2 group than in M0 group and M1 group (P<0.05). MitoSox Red and DCFH-DA stainings showed that the fluorescence intensity of the M2 group was significantly lower than that of the M1 group (P<0.05), and there was no significant difference with the M0 group (P>0.05). The M2-like BV2 cells-derived mitochondria was identified through Western blot assay. Animal experiments showed that the BMS scores of MT group at 21 and 28 days after operation were significantly higher than those of SCI group (P<0.05). At 14 days after operation, the number of iNOS-positive cells in MT group was significantly lower than that in SCI group (P<0.05), but still higher than that in sham group (P<0.05); the number of LEA-positive cells and the expression of VEGFA in MT group were significantly more than those in the other two groups (P<0.05). Conclusion M2-like macrophage/microglia-derived mitochondria transplantation can promote angiogenesis and inhibit inflammatory M1-like macrophage/microglia polarization after mouse SCI to improve function recovery.
ObjectiveTo analyze the change of differential genes and signaling pathways in high glucose induced BV2 cells, and to explore the mechanism of transgelin-2 (TAGLN2) regulating cellular inflammatory response and metabolic process. MethodsAn experimental study. The cultured BV2 cells were divided into mannitol treatment (Man) group, glucose treatment (Glu) group, overexpression control Glu treatment (Con) group, overexpression TAGLN2 Glu treatment group, silence control Glu treatment (shCon Glu) group, and silence TAGLN2 Glu treatment (shTAGLN2 Glu) group. Cells in the Man group were cultured in modified Eagle high glucose medium (DMEM) containing 25 mmol/L mannitol and 25 mmol/L glucose, cells in other groups (Glu group, Con Glu group, TAGLN2 Glu group, shCon Glu group and shTAGLN2 Glu group) were cultured in DMEM medium containing 50 mmol/L glucose. After 24 hours of cells culture, transcriptome sequencing of cells in each group were performed using high-throughput sequencing technology, and significantly differentially expressed genes (DEG) were screened. |log2 (fold change)|≥1 and P≤0.05 were adopted as criteria to screen for DEG. Gene Ontology (GO) function enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and protein-protein interaction network analysis were performed. Real-time polymerase chain reaction (RT-PCR) was used to detect the relative expression level of DEG mRNA. The data between groups were compared by independent sample t-test. ResultsWhen compared with Man group, a total of 517 differentially expressed genes were screened in Glu group, which including 277 up-regulated genes and 240 down-regulated genes. KEGG pathway enrichment analysis showed that the up-regulated genes were significantly enriched in immune system processes such as nuclear factor (NF)-κB signal pathway, Jak-signal transducers and activators of transcription (STAT) signal pathway, while down-regulated genes were significantly enriched in glycosaminoglycan degradation and glyceride metabolic pathway. Compared with Con Glu group, a total of 480 DEG were screened in TAGLN2 Glu group, among which 147 up-regulated and 333 down-regulated genes were detected. Up-regulated genes were significantly enriched in the metabolic processes of fatty acid, glyceride and pyruvate, while down-regulated genes were significantly enriched in immune system processes such as NF-κB signal pathway, Jak-STAT signal pathway and tumor necrosis factor (TNF) signal pathway. Compared with shCon Glu group, a total of 582 DEG were screened in shTAGLN2 Glu group, among which 423 up-regulated and 159 down-regulated genes were detected. Up-regulated DEG were significantly enriched in immune system processes such as TNF signal pathway and chemokine signal pathway, while down-regulated DEG were significantly enriched in pattern recognition receptor signal pathway. RT-PCR results showed that the relative expression levels of DEG mRNA Card11 (t=13.530), Icos (t=3.482), Chst3 (t=6.949), Kynu (t=5.399), interleukin (IL)-1β (t=2.960), TNF-α (t=5.800), IL-6(t=3.130), interferon-γ (t=7.690) and IL-17 (t=6.530) in the TAGLN2 Glu treatment group were decreased significantly compared with Con Glu group, and the difference was statistically significant. ConclusionTAGLN2 can inhibit glucose induced microglia inflammation by NF-κB and Jak-STAT signaling pathways, Card11, Icos, Chst3 and Kynu play an important role in the anti-inflammatory process of TAGLN2.
Objective To explore the role of hydrogen peroxide (H2O2) in inducing chronic oxidative stress in microglia aging. Methods BV2 microglia purchased from ATCC in less than 10 generations were treated with 0, 50, 100, 200 μmol/L H2O2 at different concentrations. According to the concentration of H2O2 used, the BV2 microglia were divided into a control group and H2O2 -50 μmol/L Group, H2O2 -100 μmol/L Group, H2O2 -200 μmol/L Group. Cell proliferation was measured by CCK8 cell proliferation assay. Age-related β-galactosidase (SA-β-gal) staining assay, and expression of age-related cyclin molecules p16, p21, p53 and senescence sssociated secretory phenotype interleukin 1 beta (IL-1β), transforming growth factor-β (TGF-β) and matrix metalloprotein 9 (MMP9) detected by quantitative real-time polymerase chain reaction were used to measure celluar senescence. Results During the induction process, H2O2-200 μmol/L caused significant damage to BV2 microglia, therefore no subsequent testing was conducted. Finally, the control group, H2O2-50 μmol/L group and H2O2-100 μmol/L group cells were collected. The differences in cell survival rate (F=46.176, P<0.001) and positive rate of SA-β-gal staining (F=553.1, P<0.001) among the three groups were statistically significant. The cell survival rate of H2O2-50 μmol/L group had no significant change (P>0.05), while the cell survival rate of H2O2-100 μmol/L group decreased significantly (P<0.001). The positive rate of SA-β-gal staining in H2O2-50 μmol/L group and H2O2-100 μmol/L group was increased (P<0.001), and the positive rate of SA-β-gal staining in H2O2-100 μmol/L group was higher than that in H2O2-50 μmol/L group (P<0.001). The mRNA levels of senescence related cyclin molecules p16, p21 and p53 were up-regulated under the induction of 50, 100 μmol/L H2O2 (P<0.05), and the expressions of IL-1β, TGF-β and MMP9 of senescence associated secretory phenotype were increased (P<0.05). The increase of H2O2-50 μmol/L group was more obvious (P<0.05). Conclusion The aging model of BV2 microglia can be successfully established by inducing 8 d with 100 μmol/L H2O2, and the mechanism may be related to promoting the secretion of p16, p21, p53, IL-1β, TGF-β and MMP9.
Objective To investigate the effect of M2 microglia (M2-MG) transplantation on spinal cord injury (SCI) repair in mice. Methods Primary MG were obtained from the cerebral cortex of 15 C57BL/6 mice born 2-3 days old by pancreatic enzyme digestion and identified by immunofluorescence staining of Iba1. Then the primary MG were co-cultured with interleukin 4 for 48 hours (experimental group) to induce into M2 phenotype and identified by immunofluorescence staining of Arginase 1 (Arg-1) and Iba1. The normal MG were harvested as control (control group). The dorsal root ganglion (DRG) of 5 C57BL/6 mice born 1 week old were co-cultured with M2-MG for 5 days to observe the axon length, the DRG alone was used as control. Forty-two 6-week-old female C57BL/6 mice were randomly divided into sham group (n=6), SCI group (n=18), and SCI+M2-MG group (n=18). In sham group, only the laminae of T10 level were removed; SCI group and SCI+M2-MG group underwent SCI modeling, and SCI+M2-MG group was simultaneously injected with M2-MG. The survival of mice in each group was observed after operation. At immediate (0), 3, 7, 14, 21, and 28 days after operation, the motor function of mice was evaluated by Basso Mouse Scale (BMS) score, and the gait was evaluated by footprint experiment at 28 days. The spinal cord tissue was taken after operation for immunofluorescence staining, in which glial fibrillary acidic protein (GFAP) staining at 7, 14, and 28 days was used to observe the injured area of the spinal cord, neuronal nuclei antigen staining at 28 days was used to observe the survival of neurons, and GFAP/C3 double staining at 7 and 14 days was used to observe the changes in the number of A1 astrocytes. Results The purity of MG in vitro reached 90%, and the most of the cells were polarized into M2 phenotype identified by Arg-1 immunofluorescence staining. M2-MG promoted the axon growth when co-cultured with DRGs in vitro (P<0.05). All groups of mice survived until the experiment was completed. The hind limb motor function of SCI group and SCI+M2-MG group gradually recovered over time. Among them, the SCI+M2-MG group had significantly higher BMS scores than the SCI group at 21 and 28 days (P<0.05), and the dragging gait significantly improved at 28 days, but it did not reach the level of the sham group. Immunofluorescence staining showed that compared with the SCI group, the SCI+M2-MG group had a smaller injury area at 7, 14, and 28 days, an increase in neuronal survival at 28 days, and a decrease in the number of A1 astrocytes at 7 and 14 days, with significant differences (P<0.05). ConclusionM2-MG transplantation improves the motor function of the hind limbs of SCI mice by promoting neuron survival and axon regeneration. This neuroprotective effect is related to the inhibition of A1 astrocytes polarization.
Objective To investigate the effect of N-acetylserotonin (NAS) on the retinal microglia polarization in retinal ischemia-reperfusion injury (RIRI) rats and explore its mechanism via nucleotide-bound oligomeric domain 1 (NOD1)/receptor interacting protein 2 (Rip2) pathway. MethodsHealthy male Sprague Dawley rats were randomly divided into Sham (n=21), RIRI (n=21) and NAS (injected intraperitoneally 30 min before and after modeling with NAS, 10 mg/kg, n=18) groups, using random number table. And the right eye was used experimental eye. The RIRI model of rats in RIRI group and NAS group was established by anterior chamber high intraocular pressure method. Rats in NAS group were intraperitoneally injected with 10 mg/kg NAS before and 30 min after modeling, respectively. The retinal morphology and the number of retinal ganglion cell (RGC) in each group were detected by hematoxylin-eosin staining and immunohistochemical staining. The effect of NAS on polarization of retinal microglia was detected by immunofluorescence staining. Transcriptome sequencing technology was used to screen out the differentially expressed genes between Sham and RIRI groups. Western blot and real-time quantitative polymerase chain reaction (RT-PCR) were used to examine the differentially expressed genes. Immunohistochemical staining, Western blot and RT-PCR were used to investigate the effect of NAS on the expression of NOD1 and Rip2 protein and mRNA in retinal tissue and microglia of rats. General linear regression analysis was performed to determine the correlation between the number difference of NOD1+ cells and the number difference of M1 and M2 microglia in retinal tissues of rats in NAS group and RIRI group. ResultsA large number of RGC were observed in the retina of rats in Sham group. 24 h after modeling, compared with Sham group, the inner retinal thickness of rats in RIRI group was significantly increased and the number of RGC was significantly decreased. The thickness of inner retina in NAS group was significantly thinner and the number of RGC was significantly increased. Compared with Sham group, the number of retinal microglia of M1 and M2 in RIRI group was significantly increased. Compared with RIRI group, the number of M1 microglia decreased significantly and the number of M2 microglia increased significantly in NAS group. There was statistical significance in the number of M1 and M2 microglia in the retina of the three groups (P＜0.05). Transcriptome sequencing results showed that retinal NOD1 and Rip2 were important differential genes 24 h after modeling. The mRNA and protein relative expressions of NOD1 and Rip2 in retina of RIRI group were significantly higher than those of Sham group, with statistical significance (P＜0.05). The number of NOD1+ and Rip2+ cells and the relative expression of mRNA and protein in retinal microglia in RIRI group were significantly higher than those in Sham group, and NAS group was also significantly higher than that in Sham group, but lower than that in RIRI group, with statistical significance (P＜0.05). The number of Iba-1+/NOD1+ and Iba-1+/Rip2+ cells in retinal microglia in RIRI group was significantly increased compared with that in Sham group, and the number of Iba-1+/Rip2+ cells in NAS group was significantly decreased compared with that in RIRI group, but still significantly higher than that in Sham group, with statistical significance (P＜0.05). Correlation analysis results showed that the difference of retinal NOD1+ and Rip2+ cells in NAS group and RIRI group was positively correlated with that of M1 microglia (r=0.851, 0.895), and negatively correlated with that of M2 microglia (r=−0.797, −0.819). The differences were statistically significant (P＜0.05). ConclusionNAS can regulate the microglial polarization from M1 to M2 phenotype, the mechanism is correlated with the NOD1/Rip2 pathway.