Effect of the NLRP3 inflammasome on increased hypoxic ventilation response after CIH exposure in mice.

BACKGROUND: Chronic intermittent hypoxia (CIH) increases the hypoxic ventilation response (HVR). The downstream cytokine IL-1ß of the NLRP3 inflammasome regulates respiration by acting on the carotid body (CB) and neurons in the respiratory center, but the effect of the NLRP3 inflammasome on HVR induced by CIH remains unclear. OBJECTIVE: To investigate the effect of NLRP3 on the increased HVR and spontaneous apnea events and duration induced by CIH, the expression and localization of NLRP3 in the respiratory regulatory center of the rostral ventrolateral medulla (RVLM), and the effect of CIH on the activation of the NLRP3 inflammasome in the RVLM. METHODS: Eighteen male, 7-week-old C57BL/6 N mice and eighteen male, 7-week-old C57BL/6 N NLRP3 knockout mice were randomly divided into CON-WT, CON-NLRP3-/-, CIH-WT and CIH-NLRP3-/- groups. Respiratory changes in mice were continuously detected using whole-body plethysmography. The expression and localization of the NLRP3 protein and the formation of apoptosis-associated speck-like protein containing CARD (ASC) specks were detected using immunofluorescence staining. RESULTS: NLRP3 knockout reduced the increased HVR and the incidence and duration of spontaneous apnea events associated with CIH. The increase in HVR caused by CIH partially recovered after reoxygenation. After CIH, NLRP3 inflammasome activation in the RVLM, which is related to respiratory regulation after hypoxia, increased, which was consistent with the trend of the ventilation response. CONCLUSION: The NLRP3 inflammasome may be involved in the increase in the HVR and the incidence and duration of spontaneous apnea induced by CIH. NLRP3 inhibitors may help reduce the increase in the HVR after CIH, which is important for ensuring sleep quality at night in patients with obstructive sleep apnea.

[Effects of propranolol on biological function of human esophageal squamous cell carcinoma cells].

Objective: To investigate the effects of propranolol on the subcutaneous tumorigenesis of esophageal squamous cell carcinoma (ESCC) cells and the proliferation, migration, cell cycle, apoptosis and autophagy of ESCC cells and its possible molecular mechanisms. Methods: The cell proliferation was detected by MTT (methyl thiazol tetrazolium) assay: ESCC Eca109, KYSE-450 and TE-1 cells were routinely cultured. PBS (Phosphate buffer saline) group (without propranolol) and treated groups (40, 60, 80, 100 µmol/L propranolol) were set up with 5 wells in each group. After treatment for 0, 24, 48, 72 h, 10 µl (5 mg/ml) of MTT was added to each well, and the absorbance was measured at 490 nm. The cell migration was tested by Transwell assay: ESCC Eca109, KYSE-450 and TE-1 cells were routinely cultured, and PBS group (without propranolol) and treated groups (40, 60 µmol/L) were set up with 2 wells in each group. Photos were taken 40 h later, and the experiment was repeated for three times before statistical analysis. The cell cycle and apoptosis were detected by flow cytometry assay: ESCC Eca109, KYSE-450 and TE-1 cells were routinely cultured. PBS group (without propranolol) and treated group (80 µmol/L) were set up, fixed, stained, and fluorescence at 488 nm was detected. The protein levels were detected by Western blot: ESCC Eca109 and KYSE-450 cells were routinely cultured. PBS group (without propranolol) and treated groups (60, 80 µmol/L) were set up followed by gel electrophoresis, wet membrane transfer, and ECL imaging. The experiment was repeated for three times and then analyzed statistically. Subcutaneous tumor formation experiment in nude mice: 10 nude mice were assigned PBS group (without propranolol) and treated group (with propranolol). Five mice in each group were inoculated with 5×106 cells/100 µl (Eca109) into the right underarm. The treated group was given a gavage of 0.4 ml/kg (6 mg/kg) every other day, and the tumor size was measured every other day for 3 weeks. After 20 days, the nude mice were dislocated and sacrificed to take tumor tissue. Result: The results showed that propranolol inhibited the proliferation of Eca109, KYSE-450 and TE-1 cells with IC50 of around 70 µmol/L for 48 h. Eca109, KYSE-450 and TE-1 cell migration was inhibited by propranolol in a dose-dependent manner (P＜0.05); Propranolol blocked the cell cycle of Eca109 in G2/M phase, blocked the cell cycle of KYSE-450 and TE-1 in G0/G1 phase, and promoted apoptosis of three kinds of cells (P＜0.05). The results of cell fluorescence showed that LC3 fluorescence intensity of TE-1 was increased after 12 h, 24 h and 36 h treatment with propranolol (P＜0.05). Western blot results showed that compared with PBS group, the protein expressions of p-mTOR, p-Akt and cyclin D1 were down-regulated, while cleaved caspase 9 level was up-regulated (P＜0.05). The results of subcutaneous tumor formation in nude mice showed that the tumor weight of PBS group was (0.91±0.05)g, and that of the experimental group was(0.65±0.12)g, the difference was statistically significant (P＜0.05). Conclusion: Propranolol inhibits the proliferation, migration and cell cycle,promotes apoptosis and autophagy of ESCC cells, and inhibits subcutaneous tumor growth in nude mice. The mechanism might be related to the inhibition of PI3K/AKT/mTOR signaling pathway.