Protective Effects of Anti-IL17 on Acute Lung Injury Induced by LPS in Mice

Abstract

Introduction: T helper 17 (Th17) has been implicated in a variety of inflammatory lung and immune system diseases. However, little is known about the expression and biological role of IL-17 in acute lung injury (ALI). We investigated the mechanisms involved in the effect of anti-IL17 in a model of lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. Methods: Mice were pre-treated with anti-IL17, 1h before saline/LPS intratracheal administration alongside non-treated controls and levels of exhaled nitric oxide (eNO), cytokine expression, extracellular matrix remodeling and oxidative stress, as well as immune cell counts in bronchoalveolar lavage fluid (BALF), and respiratory mechanics were assessed in lung tissue. Results: LPS instillation led to an increase in multiple cytokines, proteases, nuclear factor-κB, and Forkhead box P3 (FOXP3), eNO and regulators of the actomyosin cytoskeleton, the number of CD4+ and iNOS-positive cells as well as the number of neutrophils and macrophages in BALF, resistance and elastance of the respiratory system, ARG-1 gene expression, collagen fibers, and actin and 8-iso-PGF2α volume fractions. Pre-treatment with anti-IL17 led to a significant reduction in the level of all assessed factors. Conclusions: Anti-IL17 can protect the lungs from the inflammatory effects of LPS-induced ALI, primarily mediated by the reduced expression of cytokines and oxidative stress. This suggests that further studies using anti-IL17 in a treatment regime would be highly worthwhile.

Keywords: acute lung injury; inflammation mediators; interleukin 17; oxidative stress; remodeling.

Figure 1

Effects of the pretreatment with anti-IL17 on mechanical evaluation: (A) Respiratory system resistance and (B) Respiratory system elastance. *P < 0.05 compared with SAL and SAL-antiIL17 groups; **P < 0.05 compared to the LPS group.

Figure 2

Effects of the pretreatment with anti-IL17 on exhaled nitric oxide (ppb). *P < 0.05 compared to the SAL, SAL-antiIL17 and LPS-antiIL17 groups.

Figure 3

Effects of the pretreatment with anti-IL17 on BALF. (A) Total cells, (B) cell differential for macrophages, (C) cell differential for neutrophils, (D) cell differential for Lymphocytes, and (E) cell differential for eosinophils. The results are expressed as x10⁴ cells/mL.*P < 0.05 compared to the SAL and SAL-antiIL17 groups; **P < 0.05 compared to the LPS group.

Figure 4

Effects of the pretreatment with anti-IL17 on alveolar collapse (%) and photomicrographs of alveolar collapse. Magnification x1000. Arrow: alveolar collapse. All experimental groups are represented: SAL, LPS, SAL-antiIL17 and LPS-antiIL17 groups. *P < 0.05 compared to the SAL and SAL-antiIL17 groups; **P < 0.05 compared to the LPS group.

Figure 5

Effects of the pretreatment with anti-IL17 on (A) IL-8 and (B) IL-10-positive cells in lung tissue. *P < 0.05 compared to the SAL and SAL-antiIL17 groups; **P < 0.05 compared to the LPS group.

Figure 6

Effects of the pretreatment with anti-IL17 on (A) IL-6-positive cells, (B) IL-6 gene expression (AU), (C) IL-17-positive cells and (D) IL-17 gene expression (AU) in lung tissue. *P < 0.05 compared to the SAL and SAL-antiIL17 groups; **P < 0.05 compared to the LPS group.

Figure 7

Effects of the pretreatment with anti-IL17 on (A) TNF-α-positive cells, (B) TNF-α cytokines levels, (C) IL-1β-positive cells and (D) IL-1β cytokines levels in lung tissue.*P < 0.05 compared to the SAL and SAL-antiIL17 groups; **P < 0.05 compared to the LPS group.

Figure 8

Effects of the pretreatment with anti-IL17 on (A) CD4+ and (B) FOXP3-positive cells in lung tissue. *P < 0.05 compared to the SAL and SAL-antiIL17 groups; **P < 0.05 compared to the LPS group.

Figure 9

Effects of the pretreatment with anti-IL17 on p65-NFκB-positive cells in lung tissue. *P < 0.05 compared to the SAL and SAL-antiIL17 groups; **P < 0.05 compared with LPS group.

Figure 10

Effects of the pretreatment with anti-IL17 on (A) ROCK1 and (B) ROCK2-positive cells in lung tissue. *P < 0.05 compared to the SAL and SAL-antiIL17 groups; **P < 0.05 compared to the LPS group.

Figure 11

Inflammatory markers in lung tissue: Photomicrographs of TNF-α, IL-1β and IL-17 immunohistochemical stain showing extracellular matrix inflammation in lung tissue. Magnification x1000. All experimental groups are represented: SAL, LPS, SAL-antiIL17, and LPS-antiIL17 groups. Arrow: positive cells. Scale bar = 10 μm.

Figure 12

Remodeling and oxidative stress markers in lung tissue: Photomicrographs of immunohistochemical stains showing extracellular matrix remodeling and oxidative stress in lung tissue by detecting collagen fibers, iNOS and 8-iso-PGF2α. Magnification of ×1000. All experimental groups are represented: SAL, LPS, SAL-antiIL17 and LPS-antiIL17 groups. Arrow: positive cells. Scale bar = 10 μm.