IL-17A deficiency mitigates bleomycin-induced complement activation during lung fibrosis [Research]

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 (il17a–/–) mice were protected against bleomycin (BLEO)-induced fibrosis and collagen deposition. Further, BLEO-injured il17a–/– 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-1...
Source: FASEB Journal - Category: Biology Authors: Tags: Research Source Type: research