The Global Transcriptomic Signature In Sinonasal Tissues Reveals Roles For Tissue Type And Chronic Rhinosinusitis Disease Phenotype

Background: RNA sequencing (RNA-Seq) allows the characterization of a global transcriptomic signature in a least-biased fashion, but few studies have applied this method to investigate the pathophysiology of CRS.Methods: We collected mucosal tissue samples from 6 CRS without nasal polyps (CRSsNP), 6 CRS with nasal polyps (CRSwNP), and 6 control patients. Additional matched polyp samples were collected from the 6 CRSwNP patients. RNA was extracted and sequenced on the Illumina HiSeq-2500. Differential gene expression and pathway analyses were performed.Results: CRSsNP showed evidence of upregulated interferon-mediated immunity, MHC-class-I mediated antigen presentation, CXCR3 binding, neutrophil chemotaxis and degranulation, and potential downregulation of genes related to cilia movement and production. CRSwNP polyp tissue showed upregulation of B-cell mediated immune responses, but reduced expression of genes related to epithelial morphogenesis and haemostasis. Polyps also showed a generalized reduction of positive gene regulation. The sinonasal transcriptomic signature was largely determined by tissue type (polyp versus mucosa) and disease phenotype, with minimal signal originating from the individual patient.Conclusion: RNA-Seq is a useful tool to explore the complex pathophysiology of CRS. Our findings stress the importance of tissue selection in molecular research utilizing sinonasal tissue, and demonstrate the limitation of the sNP/wNP paradigm (and the importance of endotyping). On the other hand, classical CRSsNP/wNP disease phenotypes played some role in determining the global transcriptomic signature, and should not be hastily discarded. The value of RNA-Seq-described transcriptomic signatures in exploring endotypes is yet to be explored in future studies.