Figure 4.

SPL in combination with XPB knockdown further suppresses TNFα target genes in PAECs. (A) XPB knockdown and SPL treatment both significantly reduced XPB protein levels, but the impact of SPL was significantly greater and similar in control siRNA (siCTRL) and XPB siRNA transfected PAECs (P = 0.27 for the interaction between SPL and XPB knockdown). Densitometric quantification of XPB protein expression relative to β-actin is presented as the geometric mean ratio ± geometric SE on log₁₀ scale of four independent experiments, each with a different donor. A representative Western blot is shown below the graph. (B) SPL suppressed TNFα-induced IL8, IL6, and CCL2, but not NFKBIA (P = 0.39) mRNA expression in PAECs transfected with siCTRL. XPB knockdown alone in PAECs did not suppress, but rather modestly increased TNFα-induced IL8 (P = 0.03), IL6 (P = 0.003), CCL2 (P = 0.005), and NFKBIA (P = 0.008) expression levels compared with siCTRL. However, compared with SPL alone, the combination of XPB knockdown and SPL had the strongest suppressive effect on TNFα-induced IL8, IL6, CCL2, and NFKBIA. Expression of mRNA measured by quantitative real-time PCR is presented as the fold-change relative to unstimulated cells transfected with siCTRL (geometric mean ± geometric SE) of four independent experiments, each with a different donor, plotted on log₁₀ scale. **P < 0.01; ***P < 0.001; ****P ≤ 0.0001 (ANOVA with post hoc tests, as indicated).