Fig. 6: Interleukin (IL)−6 regulates the proliferation of human bronchial smooth muscle cells (hbSMC) via FoxO1.

For the experiments with STAT3-inhibitor (Stattic) and AKT inhibitor (AKT-Inh.), hbSMC were pre-exposed to either Stattic, AKT-Inh. or vehicle for 2 h. Subsequently, the hbSMC were stimulated as indicated. A Immunoblot showing phosphorylated STAT3 (pSTAT3) in hbSMC after exposure to IL-6 with soluble IL-6 receptor (IL-6 + R) or vehicle for 30 min. B Immunoblot showing pAKT and total AKT in hbSMC after exposure to vehicle, IL-6 + R, or Stattic for 30 min. β-actin was used as a loading control. A densitometric summary is displayed. C Nuclear and cytoplasmatic phosphorylated FoxO1 (pFoxO1) fraction in % of total cell pFoxO1 per hbSMC using immunofluorescent staining; hbSMC were treated with IL-6 + R alone or combined with AKT-Inh. or vehicle for 30 min. D Nuclear and cytoplasmatic pFoxO1 fraction in % of total cell pFoxO1 per hbSMC using immunofluorescent staining; hbSMC were treated with insulin alone or combined with AKT-Inh. or Stattic. E Nuclear and cytoplasmatic pFoxO1 fraction in % of total cell pFoxO1 per hbSMC using immunofluorescent staining; hbSMC were treated with IL-6 + R or insulin alone or both in combination with AKT-Inh. or Stattic for 30 min. F Viability (MTT assay) of hbSMC after exposure to vehicle, IL-6 + R, Paclitaxel and/or Stattic. G–I hbSMCs were exposed to IL-6 + R or vehicle with or without Paclitaxel for 30 min (G) or 24 h (H, I). Nuclear and cytoplasmatic pFoxO1 fraction in % of total cell pFoxO1 per bSMC (G); total FoxO1 per hbSMC (H), and proliferation (BrdU) of hbSMC (I). Data are shown as mean ± standard error of the mean. A–I n = 3–5 biological independent samples or experiments per group; (repeated measure) one-way ANOVA followed by the Bonferroni post-test or the two-sided Mann–Whitney test; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. Gray = vehicle; white = stimulation; orange = Paclitaxel; blue = IL-6. A detailed list of sample sizes and P value per graph is provided in the Supplemental Material. Source data are provided as a Source Data file.