Circulating cell-free messenger RNA secretome characterization of primary sclerosing cholangitis

BACKGROUND & AIMSPrimary sclerosing cholangitis (PSC) is a rare chronic cholestatic liver disease characterized by multi-focal bile duct strictures. To date, underlying molecular mechanisms of PSC remain unclear and therapeutic options for PSC patients are limited. We performed cell-free messenger RNA (cf-mRNA) next generation sequencing (RNA-Seq) to characterize the circulating transcriptome of PSC and non-invasively investigate potentially bioactive signals that are associated with PSC.METHODSSerum cf-mRNA profiles were compared among 50 individuals with PSC, 20 healthy controls, and 235 individuals with non-alcoholic fatty liver disease (NAFLD). Tissue and cell type-of-origin genes that are dysregulated in subjects with PSC were evaluated. Subsequently, diagnostic classifiers were built using PSC dysregulated cf-mRNA genes.RESULTSDifferential expression analysis of the cf-mRNA transcriptomes of PSC and healthy controls resulted in identification of 1407 dysregulated genes. Furthermore, differentially expressed genes between PSC and the liver diseases (NAFL and Non-Alcohol Steatohepatitis (NASH)) or healthy controls shared common genes known to be involved in liver pathophysiology. In particular, genes from liver- and specific cell type-origin, including hepatocyte, hepatic stellate cells and Kupffer cells, were highly abundant in cf-mRNA of subjects with PSC. Gene cluster analysis revealed that liver-specific genes dysregulated in PSC form a distinct cluster which corresponded to a subset of the PSC subject population. Finally, we developed a cf-mRNA classifier using liver-specific genes which discriminated PSC from healthy control subjects using gene transcripts of liver origin.CONCLUSIONSBlood-based whole transcriptome cf-mRNA profiling revealed high abundance of liver-specific genes in PSC subject sera which may be used to diagnose PSC patients. We identified several unique cf-mRNA profiles of subjects with PSC. These findings may also have utility for non-invasive molecular stratification of subjects with PSC for pharmacotherapy safety and response studies.Graphical Abstract