Figure 4.

Analysis of the role of IL-17A and neutrophils in induction of airway hyperreactivity in the LPS model. IL-17A^-/- mice (on BALB/c background) were exposed to LPS (2 µg in 50 µl saline) via the nose for four consecutive days ( Supplementary Figure 1A ). Twenty-four hours after the last LPS challenge, lung function parameters were measured using the FlexiVent and BAL fluid was obtained for differential cell count. Airway resistance [Rn, (A)] and FEV_0.1 [%, (B)] before and after methacholine provocation (0–20 mg/ml) were measured in saline-treated IL-17A^-/- mice (n = 8) and LPS-treated IL-17A^-/- mice (n = 8). (C) Differential cell count in BAL fluid of the same mice. (D–F) Neutrophils were depleted by anti-Ly6G mAb (250 μg injected intraperitoneally on days -1, 1, and 3 as shown in Supplementary Figure 1B ). Twenty-four hours after the last LPS challenge, lung function parameters were measured using the FlexiVent and BAL fluid obtained for differential cell count. Airway resistance [Rn, (D)] and FEV_0.1 [%, (E)] before and after methacholine provocation (0–20 mg/ml) were measured in saline-treated isotype injected wild type mice (n = 5), LPS-treated isotype injected wild-type mice (n = 5) and LPS-treated and anti-Ly6G-injected wild-type mice (n = 8). (F) Differential cell count in BAL fluid of the same mice. *p <0.05; ***p < 0.001; ****p < 0.0001 (WT saline versus WT LPS and saline + isotype versus LPS + isotype). ^##p < 0.01; ^####p < 0.0001 (IL17A^-/- saline versus IL-17A^-/- LPS). ^$$$$p < 0.0001 (LPS + isotype versus LPS + anti-Ly6G).