FIGURE 5.

Interleukin (IL)-1 downregulates collagen 1 (COL1) and α-smooth muscle actin (α-SMA) expression in pulmonary arterial smooth muscle cells (PASMCs) and parenchymal fibroblasts. IL: interleukin; C_t: cycle threshold; α-TUB: α-tubulin; PDGF: platelet-derived growth factor; NC: negative control. a, b) Relative expression levels of Col1a1 and Acta2 after 4, 8 and 24 h of IL-1α (1 ng·mL⁻¹) and IL-1β (10 ng·mL⁻¹) stimulation in a) PASMCs and b) parenchymal fibroblasts (extracellular matrix production). Data from six independent experiments with cells isolated from different donor lungs are depicted. B2m (β₂-microglobulin) and Hmbs (hydroxymethylbilane synthase) were used as reference genes. c, d) Representative Western blots of COL1 and α-SMA in c) PASMCs and d) parenchymal fibroblasts treated with IL-1α and IL-1β for 4, 8 or 24 h. e, f) Proliferation of e) PASMCs and f) parenchymal fibroblasts assessed by ³H-thymidine incorporation over 24 h upon stimulation with IL-1α, IL-1β and PDGF-BB. Data from 10 independent experiments on cells from five different donors; mean±sd. *: p<0.05, Kruskal–Wallis test with Dunn's post-test for multiple comparisons.