Fig 1.
IL-17C mediates chronic neutrophilic inflammation.
WT and Il-17c-/- mice were exposed to heat-inactivated NTHi three times a week (day 1, 3, 5) for 4 weeks. Numbers of total immune cells (A), neutrophils (B), macrophages (C), and lymphocytes (D) were determined in BAL fluids 24 hours after the final exposure to NTHi (n = 6–7 per group). Data were compared by One-way ANOVA with Bonferroni post-test and are shown as the mean ± SD. *p < 0.05 and **p < 0.01.
Fig 2.
Reduced lung damage in mice deficient for IL-17C.
WT and Il-17c-/- mice were exposed to heat-inactivated NTHi three times a week (day 1, 3, 5) for 4 weeks. Mice were analyzed 24 hours after the final exposure to NTHi. Representative IHC of Ly6B (A) and CD3 (B) and quantification of the Ly6B+ and CD3+ cells in lung parenchyma (n = 6 mice per group, 6–8 fields per mouse, Scale bar: 50 μm). Representative lung histology (C, hematoxylin and eosin staining) and inflammatory score (D) (n = 9–10 per group, 2–3 lung sections per mouse, scale bar: 100 μm). Data were compared by unpaired Student’s t-test and are shown as the mean ± SD. *p < 0.05 and **p < 0.01. (E) The mean chord length (MCL, 27–50 fields per mouse, n = 9–10 per group) was determined by morphometric methods. Data were compared by One-way ANOVA with Bonferroni post-test and are shown as the mean ± SD. *p < 0.05 and ***p < 0.001.
Fig 3.
Il-17c deletion decreases the expression of inflammatory cytokines.
WT and Il-17c-/- mice were exposed to heat-inactivated NTHi three times a week (day 1, 3, 5) for 4 weeks. Mice were analyzed 24 hours after the final exposure to NTHi. (A) Relative expression of IL-17C, IL-6, G-CSF, and KC in lung tissue (n = 5–6 mice per group). Data were compared by One-way ANOVA with Bonferroni post-test and are shown as the mean ± SD. **p < 0.01, and ***p < 0.001. (B) Concentrations of IL-6, G-CSF, and KC in BAL fluids (n = 4–7 mice per group). (C) Polarized primary alveolar epithelial cells were stimulated with inactivated NTHi (0.25 mg/ml protein in PBS). The expression of IL-17C was measured by qRT-PCR after 24 hours. Data were compared by Mann-Whitney test and are shown as the median with interquartile range. p < 0.05 and **p < 0.01.
Fig 4.
IL-17C does not contribute to CS-induced lung inflammation.
WT and Il-17c-/- mice were exposed to CS for 4 weeks five times a week (days 1–5). Numbers of total immune cells (A), macrophages (B), neutrophils (C), and lymphocytes (D) were determined in BAL 24 hours after the final exposure to CS (n = 4–5 mice per group). Data were compared by unpaired Student’s t-test and are shown as the mean ± SD. *p < 0.05, **p < 0.01, and ***p < 0.001.
Fig 5.
IL-17C contributes to acute COPD-like lung inflammation.
WT and Il-17c-/- mice were exposed to NTHi (day 1, 3, and 5) or the combination of NTHi (day 1, 3, 5) and CS (day 1 to 5). Numbers of total immune cells (A), neutrophils (B), macrophages (C), and lymphocytes (D) were determined in BAL fluids 24 hours after the final exposure to NTHi (n = 7 per group). Concentrations G-CSF (E), MIP-2 (F), and KC (G) were measured in lung homogenate (n = 4–7 mice per group). Data were compared by One-way ANOVA with Bonferroni post-test and are shown as the mean ± SD. *p < 0.05, **p < 0.01, and ***p < 0.001.
Fig 6.
IL-17C concentrations are increased during advanced COPD.
(A) Concentrations of IL-17A, IL-17C, and IL-17E in sputum collected from GOLD I/II and GOLD III/IV COPD patients during AECOPD. (B) Concentrations of IL-17C in sputum separated in male (m) and female (f) donors. Horizontal lines indicate mean values. (C) Association of IL-17C concentrations with FEV1 (%) predicted. Correlation analysis was performed using nonparametric Spearman’s correlation test.
Fig 7.
Negative correlation between IL-17C and IL-17E concentrations.
Sputum was collected from COPD patients during AECOPD. Correlation of IL-17C with indicated cytokines was tested using nonparametric Spearman’s correlation test.
Table 1.
Patient characteristics.
Table 2.
Concentrations of cytokines.