Transcriptional analysis of liver tissue from indeterminate pediatric acute liver failure patients

Background and Aims: Many patients with indeterminate pediatric acute liver failure (PALF) have evidence of T-cell driven immune injury, however the precise inflammatory pathways have not been well defined. We have thus characterized the hepatic cytokine and transcriptional signatures of PALF patients. Approach and Results: Retrospective review was performed on 22 children presenting with indeterminate (IND-PALF; n=17) or other diagnoses (DX-PALF; n=6) with available archived liver tissue. Specimens were stained for CD8 T-cells and scored as dense, moderate, or minimal. Measurement of immune analytes and RNA-sequencing (RNA-seq) were performed on whole liver tissue. Immune analyte data was analyzed by principal component analysis, and RNA-seq was analyzed by unsupervised hierarchical clustering, differential gene expression, and gene set enrichment analysis. Most IND-PALF patients (94%) had dense/moderate CD8 staining and were characterized by Th1 immune analytes including TNFα, IFNγ, IL-1β, IL-12, CXCL9, and CXCL12. Transcriptional analyses identified 2 transcriptional PALF phenotypes. Most patients in Group 1 (91%) had IND-PALF and dense/moderate CD8 staining. This group was characterized by increased expression of genes and cell-subset specific signatures related to innate inflammation, T-cell activation, and antigen stimulation. Group 1 also expressed significantly higher levels of gene signatures for T-regulatory cells, macrophages, Th1 cells, T effector memory cells, cytotoxic T-cells, and activated dendritic cells (p-adj <0.05). In contrast, patients in Group 2 exhibited increased expression for genes involved in metabolic processes. Conclusions: IND-PALF patients have evidence of a Th1 mediated inflammatory response driven by IFNγ. Transcriptional analyses suggest a complex immune network may regulate an immune-driven PALF phenotype with less evidence of metabolic processes. These findings provide novel insight into mechanisms of hepatic injury in PALF, areas for future research, and potential therapeutic targets. RNA sequencing of frozen liver tissue from 22 children with acute liver failure and 2 normal controls