Histamine 1 receptor agonist inhibits LPS-induced immune responses in astrocytes via Akt/NF-KB signaling pathway / 中国药理学通报

Aim To investigate the effect of histamine H, receptor (HjR) on the immune responses in astrocytes induced by lipopolysaccharide (LPS) and the regulatory mechanism of its signaling pathway. Methods LPS was used to establish an in vitro astrocyte inflammation model. Rat primary astrocytes were divided into the control group, LPS group, LPS + Hj R agonist group (2-pyridylethlamine, Pyri), and HjR agonist group. Astrocytes were treated with Pyri 100 p,mol • L~ for 1 h, then stimulated with LPS at 100 p,g • L~ for 24 h. Cell viability was measured using the CCK-8 assay. The expression of GFAP and HjR was detected by immunofluorescence. Glial morphological changes were observed under a microscope. The levels of proinflammatory mediators (TNF-a and IL-6) were detected by ELISA. The protein expressions of p-Akt, Akt, p-NF-KB p65, and NF-KB p65 were detected by Western blot. Results Compared with the control group, more activated astrocytes with fewer cell processes and branches were observed in the LPS group. Besides, LPS enhanced the GFAP expression level, reduced the H,R expression level and stimulated the production of TNF-a and IL-6 from astrocytes. Pre treatment with Pyri for 1 h ameliorated the glial morphological changes stimulated by LPS, inhibited LPS-induced upregulation of GFAP level and the inflammatory factors secretion. In addition, LPS stimulated astrocytes showed a higher phosphorylation of Akt and NF-KB p65, which was also ameliorated by Pyri. Conclusions H, R agonist can inhibit LPS-induced astrocyte activation and inflammatory factor secretion, and the Akt/NF-KB signaling pathway may be an important pathway for the involvement of H,R in immune regulation.

The TRPM4 channel inhibitor 9-phenanthrol alleviates cerebral edema after traumatic brain injury in rats.

Cerebral edema (CE) exerts an important effect on brain injury after traumatic brain injury (TBI). Upregulation of transient receptor potential melastatin 4 (TRPM4) in vascular endothelial cells (ECs) results in damage to capillaries and the blood-brain barrier (BBB), which is critical for the development of CE. Many studies have shown that 9-phenanthrol (9-PH) effectively inhibits TRPM4. The current study aimed to investigate the effect of 9-PH on reducing CE after TBI. In this experiment, we observed that 9-PH markedly reduced brain water content, BBB disruption, proliferation of microglia and astrocytes, neutrophil infiltration, neuronal apoptosis and neurobehavioral deficits. At the molecular level, 9-PH significantly inhibited the protein expression of TRPM4 and MMP-9, alleviated the expression of apoptosis-related molecules and inflammatory cytokines, such as Bax, TNF-α and IL-6, near injured tissue, and diminished serum SUR1 and TRPM4 levels. Mechanistically, treatment with 9-PH inhibited activation of the PI3K/AKT/NF-kB signaling pathway, which was reported to be involved in the expression of MMP-9. Taken together, the results of this study indicate that 9-PH effectively reduces CE and alleviates secondary brain injury partly through the following possible mechanisms: ①9-PH inhibits TRPM4-mediated Na + influx and reduces cytotoxic CE; ②9-PH hinders the expression and activity of MMP-9 by inhibiting the TRPM4 channel and decreases disruption of the BBB, thereby preventing vasogenic cerebral edema. ③9-PH reduces further inflammatory and apoptotic damage to tissues.

The Novel KLF4/BIG1 Regulates LPS-mediated Neuro-inflammation and Migration in BV2 Cells via PI3K/Akt/NF-kB Signaling Pathway.

Excessive microglia activation occurred in many neurodegenerative diseases. Brefeldin A-inhibited guanine nucleotide-exchange protein 1 (BIG1, ARFGEF1) is involved in cell migration and neurite growth. In the present study, we aimed to explore the effects and potential mechanisms of BIG1 in LPS-mediated neuro-inflammation and migration in BV2 cells. Loss-of-function and gain-of-function experiments were performed. Inflammatory cytokines (TNF-α, IL-1ß, IL-6, IL-10) mRNA levels and concentrations were analyzed by Quantitative Real-time PCR (RT-qPCR) and ELISA kits. The NO concentration was tested by ELISA kit. iNOS and COX-2 mRNA and protein levels were measured by RT-qPCR and western blot. Cell migration was determined by transwell assay. The results demonstrated that BIG1 silencing reduced TNF-α, IL-1ß, and IL-6 expression, while increased IL-10 expression. The NO production, iNOS and COX-2 expression were clearly inhibited by BIG1 knockdown in the presence of LPS. Furthermore, ablation of BIG1 attenuated the migration capacity of BV2 cells. Overexpression of BIG1 displayed the opposite trends. Moreover, we found BIG1 suppression inhibited PI3K/Akt/NF-κB pathway activation. 740Y-P, an agonist of PI3K, abolished the roles of BIG1 silencing in neuro-inflammation and migration. Additionally, ChIP-qPCR and Dual-luciferase reporter assay determined that KLF4 binds to the promoter of BIG1, western blot analysis demonstrated that KLF4 could regulate BIG1 positively. In addition, we observed that BIG1 overexpression partly rescued the biological activities of KLF4 silencing in neuro-inflammation and migration in LPS-stimulated BV2 cells. Taken together, BIG1 was mediated by KLF4 regulated LPS-mediated neuro-inflammation and migration in BV2 cells via PI3K/Akt/NF-kB signaling pathway.

Apoptotic Effect of Saccharomyces cerevisiae on Human Colon Cancer SW480 Cells by Regulation of Akt/NF-ĸB Signaling Pathway.

Drug resistance is one of the major problems, which causes recurrence of cancers. Therefore, complementary treatments are needed to improve the impacts of chemotherapy agents. The effect of probiotics as cancer-preventing agents through involvement in the activation of apoptotic pathways has been established. The present study sought to investigate how the heat-killed form of Saccharomyces cerevisiae (as a probiotic) could affect the Akt/NF-kB-induced apoptosis in colon cancer cells, the SW480 cell line. The cytotoxic effects of heat-killed yeast (HKY) and 5-fluorouracil (5-FU, as a positive control drug) were assayed using the MTT method. Morphological changes followed by apoptosis were examined using DAPI staining. The transcription and translation level of apoptosis genes were explored with qRT-PCR and western blotting. The data were analyzed using GraphPad Prism V6.0 Software. The results showed that HKY could induce apoptosis in colon cancer cell line through downregulation of p-Akt1, Rel A, Bcl-XL, pro-caspase 3, and pro-caspase 9 expressions, and upregulation of BAX, cleaved caspase-3, and cleaved caspase-9. Besides, Akt protein expression was not affected. It is noticeable that HKY had a better modulating effect on BAX expression compared with 5-FU. It was able to modulate Akt/NF-kB signaling pathway followed by the apoptotic cascade.