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IL‐17A deficiency mitigates bleomycin‐induced complement activation during lung fibrosis
Author(s) -
Cipolla Ellyse,
Fisher Amanda J.,
Gu Hongmei,
Mickler Elizabeth A.,
Agarwal Manisha,
Wilke Carol A.,
Kim Kevin K.,
Moore Bethany B.,
Vittal Ragini
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.201700289r
Subject(s) - pulmonary fibrosis , fibrosis , idiopathic pulmonary fibrosis , immunology , interleukin 17 , cytokine , bleomycin , chemistry , lung , biology , medicine , pathology , chemotherapy
Interleukin 17A (IL‐17A) and complement (C′) activation have each been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF). We have reported that IL‐17A induces epithelial injury via TGF‐β in murine bronchiolitis obliterans; that TGF‐β and the C′ cascade present signaling interactions in mediating epithelial injury; and that the blockade of C′ receptors mitigates lung fibrosis. In the present study, we investigated the role of IL‐17A in regulating C′ in lung fibrosis. Microarray analyses of mRNA isolated from primary normal human small airway epithelial cells indicated that IL‐17A (100 ng/ml; 24 h; n = 5 donor lungs) induces C′ components (C′ factor B, C3 , and GPCR kinase isoform 5), cytokines ( IL8, ‐6 , and ‐ 1B ), and cytokine ligands ( CXCL1, ‐2, ‐3, ‐5, ‐6 , and ‐ 16 ). IL‐17A induces protein and mRNA regulation of C′ components and the synthesis of active C′ 3a (C3a) in normal primary human alveolar type II epithelial cells (AECs). Wild‐type mice subjected to IL‐17A neutralization and IL‐17A knockout ( i717a −/− ) mice were protected against bleomycin (BLEO)‐induced fibrosis and collagen deposition. Further, BLEO‐injured i17a −/− mice had diminished levels of circulating Krebs Von Den Lungen 6 (alveolar epithelial injury marker), local caspase‐3/7, and local endoplasmic reticular stress‐related genes. BLEO‐induced local C′ activation [C3a, C5a, and terminal C′ complex (C5b‐9)] was attenuated in il17a −/− mice, and IL‐17A neutralization prevented the loss of epithelial C′ inhibitors (C′ receptor‐1 related isoform Y and decay accelerating factor), and an increase in local TUNEL levels. RNAi‐mediated gene silencing of il17a in fibrotic mice arrested the progression of lung fibrosis, attenuated cellular apoptosis (caspase‐3/7) and lung deposition of collagen and C′ (C5b‐9). Compared to normals, plasma from IPF patients showed significantly higher hemolytic activity. Our findings demonstrate that limiting complement activation by neutralizing IL‐17A is a potential mechanism in ameliorating lung fibrosis.—Cipolla, E., Fisher, A. J., Gu, H., Mickler, E. A., Agarwal, M., Wilke, C. A., Kim, K. K., Moore, B. B., Vittal, R. IL‐17A deficiency mitigates bleomycin‐induced complement activation during lung fibrosis. FASEB J. 31, 5543–5556 (2017). www.fasebj.org