mRNA expression levels of proinflammatory cytokines in PAMs stimulated by OmpP2 or the eight loop peptides. PAMs were stimulated with OmpP2 (5 µg/mL and 10 µg/mL), loops L1–L8 or scrambled peptide (130 nmol/mL and 260 nmol/mL) for 6 and 12 h. The mRNA expression levels of IL-1α (A), IL-1β (B), IL-6 (C), IL-8 (D), IL-17 (E), IL-23 (F), CCL-4 (G) and CCL-5 (H) were measured by real-time PCR. The HEPES buffer (pH 7.4) containing 0.25% (w/v) SLS was used as a mock stimulus, and the untreated cells were used as a negative control. Values are presented as the mean ± SD of three independent experiments. Data were analysed using one-way ANOVA. *p < 0.05, **p < 0.01 compared with the negative control.