American Thoracic Society 2016 International Conference

Body: Alveolar epithelial cell injury and activation are thought to drive altered repair and fibrosis in IPF while the role of alvMAC, actively producing cytokines and chemokines and generating high levels of O2 radicals, is still unclear. To assess ex vivo alvMAC activation patterns, we analyzed transcriptome changes in uncultured, unstimulated alvMACs, Abstract Preview http://www.call4abstracts.com/ers_lb/preview.php?abs=750224... obtained by bronchoalveolar lavage (BAL) from 7 IPF patients, (age 65+3, years, 5 smokers) and 4 smoking controls (age 47+8 years). RNA was extracted from BAL cells (>80% alvMAC), cDNA libraries prepared and sequenced (82x106 + 27x106 reads, 84.5 +1.5% uniquely aligned) to identify 22,126 expressed genes (Genome Reference Consortium release UCSC mRNA database), 375 differentially expressed (178 overexpressed; log2FC >0.58, p <0.05, edgeR exactTest). Gene Ontology analysis showed "Granulocyte chemotaxis" and "Inflammatory response", upregulated, "Antioxidant activity" and "NADPH oxidase activity", downregulated, as top biological processes and functions. Gene Set Enrichment Analysis (GSEA), using the whole alvMAC transcriptome and macrophage activation pattern-associated gene lists extracted from published studies (Xue J. et al. Immunity 2014; 40: 274-288), showed significantly enriched alvMAC expression of pro-repair M2 (prevalently down-regulated) and expression of pro-inflammatory M1 (upregulated) activation pattern-characterizing genes (p<0.001). Together, the data show macrophage unrestrained pro-inflammatory activation, likely incited by ongoing high oxidative stress in the presence of downregulated anti-oxidant genes, indicating alvMACs as possible epithelial injury trigger.