Figure 4: DEX suppresses NTHi-induced innate inflammatory response in Irak-m^+/+ but not in Irak-m^−/− mice.

(a–e) WT and IRAK-M-deficient mice were inoculated with DEX (1 mg kg⁻¹, intraperitoneally) for 2 h, followed by intratracheal inoculation with NTHi (1 × 10⁷ c.f.u. per lung) for 24 h. (a) Haematoxylin and eosin (H&E) staining of lung tissues from mice (Scale bar, 200 μm, magnification, × 100 in large frame; Scale bar 50 μm, magnification, × 400 in inserted frame). (b) Blinded histopathologic scoring of lung inflammation was performed on H&E-stained lung sections in a grade 0–3. (c) The number of PMN cells from BAL fluid was counted using a haemocytometer under the microscope. (d) Bacterial loads (c.f.u.) in lung homogenates. (e) The mRNA expression of mBD4 in lung was measured by qPCR (f) WT and IRAK-M-deficient mice were inoculated with DEX (1 mg kg⁻¹, intraperitoneally) for 2 h, followed by intratracheal inoculation with lethal dose of NTHi (5 × 10⁸ c.f.u. per lung) for 7 days. Survival rate was monitored for indicated days. P values were determined by Kaplan–Meier survival analysis with GraphPad Prism 5.0. Data in b=8; c,e, n=3; d=10, f=20 are mean±s.d. *P<0.05, NS, non-significant; t-test.