Abstract
Introduction: We analyzed the transcriptome of bronchoalveolar lavage cells (BAL) in a large cohort of well characterized sarcoidosis subjects by RNA-sequencing to better understand disease progression and severity, and potentially identify novel molecular phenotypes.
Methods: BAL was performed on subjects enrolled in the Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis study (GRADS) as described (Moller et al., Ann Am Thorac Soc, 2015 PMID: 26193069). cDNA libraries were prepared from 1ug of RNA and sequenced by Ion Torrent Proton Sequencer. Cufflinks calculated Fragments per Kilobase of exon per Million (FPKM) values. Non-parametric correlation methods and Metacore identified significant genes and pathways. Weighted gene co-expression network analysis (WGCNA) revealed correlation networks between gene expression and clinical traits. Multiple hypothesis testing was controlled at FDR<0.05.
Results: 199 samples from 24 stage I, 33 stage II-III treated, 40 stage II-III untreated, 17 stage IV treated, and 12 stage IV untreated subjects were available (53.2% females, 23.1% blacks). Correlation analysis revealed that 65 genes were increased with advanced Scadding stage and 24 were decreased (FDR<0.05). 50 genes differentiated subjects with normal PFT from those with reduced. 189 genes were differentially expressed in black compared to white subjects. WGCNA revealed distinct gene modules correlated with PFT and CT features.
Conclusion: RNA-sequencing of BAL in sarcoidosis patients identified novel genes associated with features of disease. Preliminary analysis suggests the presence of molecular disease endotypes.
- Copyright ©the authors 2017