Quantitative real-time PCR (qRT-PCR)
Total RNA was extracted from each sample using a TRIzol assay kit (St. Louis, MO, USA). Then, 1 μg of RNA sample was applied to qRT-PCR using a qPCR master mix kit. SYBR green was incorporated into PCR amplification. The oligonucleotide primers derived from human for IL-1β were AAACAGATGAAGTGCTCCTTCCAGG (forward) and GGGAACTGGGCAGACTCAAA (reverse), and for GAPDH these were TGCCTCCTGCACCACCAACT (forward) and CCCCGTTCAGCTCAGGGATGA (reverse).