Gene expression profiling of non-alcoholic steatohepatitis using gene set enrichment analysis

Aim: Non-alcoholic steatohepatitis (NASH) is a subset of non-alcoholic fatty liver disease (NAFLD) and sometimes progresses to cirrhosis and liver failure. In this study we analyzed the expression profile of genes and biological pathways involved in NASH in comparison with non-NASH by gene set enrichment analysis (GSEA) employing a DNA microarray technique. Methods: mRNA from liver biopsy specimens was collected from a group of NASH patients and a group of non-NASH patients. We analyzed the relative abundance of mRNA using high-density oligonucleotide microarrays containing probes for 54 675 known genes, and investigated the pathogenetic mechanisms of NASH by means of a powerful technique for analyzing molecular profiling data, GSEA. Results: The results showed that the level of expression of 27 gene sets was significantly higher and the level of expression of 25 gene sets was significantly lower in the NASH samples than in the non-NASH samples. Based on these results we created an online, publicly available, searchable database containing the data for the gene expression profiles of the NASH patients (http://www2.genome.rcast.u-tokyo.ac.jp/__/NASH/NASH_GSEA2/). Conclusion: Our data revealed differences in expression of many gene sets that are involved in the pathogenesis of NASH.