Fig. 9
High concentration of CO2 enhances activation of NLRP3 inflammasome in hypoxic BV-2 microglia (n = 4). a The immunoreactive bands of NLRP3 (118 kDa), pro-caspase-1 (40 kDa), caspase-1 (10 kDa), and GAPDH (36 kDa). c–e There are significant interaction effects between 15% CO2 treatment and 0.2% O2 treatment (NLRP3: P < 0.01; pro-caspase-1: P < 0.01; caspase-1: P < 0.05). b Simple effects analyses show that the protein expression in HC group has no significant difference compared with control group (ns P > 0.05). The protein expression levels in hypoxia group are significantly increased compared with control group (**P < 0.01). Hypoxia + HC group has the highest levels of the protein in comparison with HC group (**P < 0.01) and hypoxia group (**P < 0.01). f Immunofluorescence images show the expression of caspase-1 (B, E, H, K, red), NLRP3 (A, D, G, J, green), and the co-localization of caspase-1 and NLRP3 (C, F, I, L). The results also show that high concentration of CO2 (15% CO2) alone is not enough to increase the expression of caspase-1 and NLRP3. The expression of caspase-1 and NLRP3 in hypoxia-activated BV-2 microglia is markedly increased. Additionally, the expression of caspase-1 and NLRP3 is further enhanced following treatment of 15% CO2 in the hypoxic BV-2 microglia. Scale bars: (A-L), 20 μm. HC group high concentration of carbon dioxide group