Gene- and exon-expression profiling reveals an extensive LPS-induced response in immune cells in patients with cirrhosis

Abstract

Background & aims: Lipopolysaccharide (LPS)-expressing bacteria cause severe inflammation in cirrhotic patients. The global gene response to LPS is unknown in cirrhotic immune cells.

Methods: Gene-expression profiling using Affymetrix Human Exon Array analyzed the expression of 14,851 genes in LPS-stimulated peripheral blood mononuclear cells (PBMCs) from 4 patients with cirrhosis and 4 healthy subjects. We performed validation studies using RT-qPCR in LPS-stimulated PBMCs from 52 patients and 9 healthy subjects and investigated the association of gene induction with mortality in 26 patients.

Results: Gene-expression profiling of LPS-stimulated cirrhotic cells showed 509 upregulated genes and 1588 downregulated genes. In LPS-stimulated "healthy" cells, 952 genes were upregulated and 838 genes downregulated. The 741 LPS-regulated genes shared by cirrhotic and "healthy" cells were involved in cytokine production/activity and induction of "immune paralysis". Comparison of functions associated with the 1356 genes, specifically regulated by LPS in cirrhotic cells, to functions of the 1049 genes, specifically regulated in "healthy" cells, allowed to define a cirrhosis-specific phenotype. Unlike in "healthy" cells, LPS failed to induce an interferon-mediated program in cirrhotic cells. In cirrhotic PBMCs, LPS specifically induced certain molecules involved in apoptosis and downregulated molecules involved in endocytic trafficking. RT-qPCR experiments showed that LPS-stimulated cirrhotic PBMCs had an enhanced induction of certain proinflammatory cytokines and chemokines. In the prognosis study, higher ex vivo LPS-induction of the inflammatory genes IL6 and CXCL5 was a significant predictor of mortality.

Conclusions: Our results show that LPS-stimulated cirrhotic PBMCs exhibit an extensive and often unexpected transcriptional response.