Figure 4. Hypercapnic acidosis activation of GPR4 increases the expression of inflammatory genes in HUVEC.

HUVECs transduced with the control vector (Vector, white bars), or GPR4 expression construct (GPR4, dark bars) were treated for 5 h with EGM-2 media buffered with ambient air, 5% CO₂ or 20% CO₂. Real-time RT-PCR quantification of mRNA levels of CXCL2 (A), CCL20 (B), IL8 (C), IL1A (D), PTGS2 (E), and CD69 (F) was performed. Ct values were normalized to the housekeeping gene GAPDH. The expression level of the target genes in HUVEC/Vector or HUVEC/GPR4 cells treated with ambient air-buffered EGM-2 medium was set as 1. Error bars indicate the mean ± SEM. *, P<0.05; **, P<0.01; ***, P<0.001; ns, not significant (P>0.05); compared with the ‘ambient air’ groups. The results shown are the average of two biological repeats.