Interferon-γ upregulates retinoic acid-inducible gene-I in human pericardial mesothelial cells

Objectives - Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH box family proteins and serves as an intracellular signalling molecule involved in the regulation of various genes. Mesothelial cells are active in generating a variety of bioactive factors, and RIG-I may serve as a potential intracellular molecule regulating part of these factors. We have addressed the expression of RIG-I in pericardial mesothelial cells. Methods and results - Cultures of human mesothelial cells separated during cardiac surgery were established. Interferon (IFN)-gamma was found to stimulate the expression, in cultured mesothelial cells, of RIG-I mRNA and protein in time- and concentration-dependent manners. We also performed immunohistochemical analysis of heart tissues to examine the expression of RIG-I in mesothelial cells. Intense immunoreactivity was detected in reactive pericardial mesothelial cells in non-specific pericarditis and in dilated cardiomyopathy. Conclusion - RIG-I may be involved in the inflammatory reaction in pericardial mesothelial cells.