LAUSR

BACKGROUND & AIMS Primary biliary cholangitis (PBC) is an autoimmune liver disease of unknown pathogenesis. Consequently, therapeutic targets for PBC have yet to be identified. CD4+ T cells play a pivotal role in immunological dysfunction observed in PBC, and therefore, microRNA (miRNA) and mRNA expression were analysed in CD4+ T cells, to investigate PBC pathogenesis and identify novel therapeutic targets. METHODS Integral miRNA and mRNA analysis of 14 PBC patients and ten healthy controls was carried out using microarray and quantitative real-time polymerase chain reaction (qRT-PCR), with gene set enrichment analysis. The functional analyses of miRNA were then assessed using reporter and miRNA-overexpression assays. RESULTS The integral analysis of miRNA and mRNA identified four significantly downregulated miRNAs (miR-181a, -181b, -374b, and -425) related to the T cell receptor (TCR) signalling pathway in CD4+ T cells of PBC. N-Ras, a regulator of the TCR signalling pathway, was found to be targeted by all four identified miRNAs. In addition, in vitro assays confirmed that decreased miR-425 strongly induced inflammatory cytokines (interleukin [IL]-2 and interferon [IFN]-γ) via N-Ras upregulation in the TCR signalling pathway. CONCLUSION The decreased expression of four miRNAs that dysregulate TCR signalling in PBC CD4+ T cells was identified. miR-425 was demonstrated as an inflammatory regulator of PBC via N-Ras upregulation. Therefore, the restoration of decreased miR-425 or the suppression of N-Ras may be a promising immunotherapeutic strategy against PBC. LAY SUMMARY Primary biliary cholangitis (PBC) is an autoimmune liver disease, but the causes are unknown. MicroRNAs are molecules known to regulate biological signals. In this study, four microRNAs were identified as being decreased in PBC patients, leading to activation of T cell receptor signalling pathways, involved in inflammation. One particular target, N-Ras, could be an attractive and novel immunotherapeutic option for PBC. TRANSCRIPT PROFILING Microarray data are deposited in GEO (GEO accession: GSE93172).