Figure 8.

Inhibition of inositol-requiring enzyme 1 α–dependent X-box–binding protein-1 mRNA splicing (XBP-1s) suppresses LPS-induced cytokine secretion in primary cultures of alveolar macrophages (AMs). Non–cystic fibrosis (CF) and CF AMs were stimulated for 6 hours with 100 ng/ml LPS from Pseudomonas aeruginosa in the absence or presence of the Inhibition of inositol-requiring enzyme 1 α inhibitor 8-formyl-7-hydroxy-4-methylcoumarin (4μ8C) (50 μM; 1 h pretreatment). Quantitative reverse transcriptase polymerase chain reaction was used to evaluate the levels of XBP-1s (A), tumor necrosis factor (TNF)-α (B), and IL-6 (C) mRNA. Data are expressed as fold change relative to 18S mRNA. TNF-α (D) and IL-6 (E) secretion into the culture media was determined by ELISA. Open bars correspond to primary cultures of non-CF AMs. Solid bars correspond to primary cultures of CF AMs. The y-axis uses a logarithmic scale for TNF-α and IL-6 mRNA and protein secretion. Data are from five independent experiments and represent mean ± SD. Unpaired t test was used to compare non-CF with CF AMs and paired t test was used to compare the different treatments. *P < 0.05, **P < 0.01, and ***P < 0.001. ND = not detected.