Postprint: A citrus extract containing flavanones represses plasminogen activator inhibitor-1 (PAI-1) expression and regulates multiple inflammatory, tissue repair, and fibrosis genes in human colon fibroblasts

The consumption of flavonoid-rich <i>Citrus</i> extracts has been associated with multiple beneficial effects including anti-inflammatory properties, but the potential effects on the inflammatory responses in the gut have not been thoroughly investigated. We used microarrays to search for molecular changes induced in human colon fibroblasts in response to the exposure to a flavanone-rich bitter orange extract under physiologically representative conditions. Dietary nontoxic levels of the predigested extract induced moderate but significant changes in the expression of genes associated with tissue repair and inflammation. Among the top regulated genes, plasminogen activator inhibitor 1 (PAI-1) was downregulated, and the matrix metallopeptidase 12 (MMP-12) was upregulated (mRNA and protein levels). Both proteins are involved in extracellular matrix (ECM) remodeling and fibroblast migration. The extract also affected the fibroblast migration and reduced monocyte adhesion, but the response was different in unstimulated cells and in cells pretreated with TNF-α. Collectively, these results were indicative of a moderate activation of the colon fibroblast inflammation-related function after exposure to the extract. Further investigations are required to identify the in vivo role of this <i>Citrus</i> derived extract in the maintenance of the normal balance in the intestine and in the pathogenesis of inflammatory diseases.