Cardiac fibroblasts play an important role in the regulation of the extracellular matrix and are newly recognized as inflammatory supporter cells. Interferon (IFN)-gamma is known to counteract transforming growth factor (TGF)-beta 1-induced myofibroblast differentiation. This study aims at investigating in vitro how IFN-gamma affects TGF-beta 1-induced monocyte attraction. Therefore, C4 fibroblasts and fibroblasts obtained by outgrowth culture from the left ventricle (LV) of male C57BL6/j mice were stimulated with TGF-beta 1, IFN-gamma and TGF-beta 1 + IFN-gamma. Confirming previous studies, IFN-gamma decreased the TGF-beta 1-induced myofibroblast differentiation, as obviated by lower collagen I, III, alpha-smooth muscle actin (alpha-SMA), lysyl oxidase (Lox)-1 and lysyl oxidase-like (LoxL)-2 levels in TGF-beta 1 + IFN-gamma-versus TGF-beta 1-stimulated cardiac fibroblasts. TGF-beta 1 + IFN-gamma-stimulated C4 and cardiac fibroblasts displayed a higher CC-chemokine ligand (CCL) 2, CCL7 and chemokine C-X3-C motif ligand (Cx3CL1) release versus sole TGF-beta 1- stimulated fibroblasts. Analysis of migrated monocyte subsets towards the different conditioned media further revealed that sole TGF-beta 1- and IFN-gamma-conditioned media particularly attracted Ly6C(low) and Ly6C(high) monocytes, respectively, as compared to control media. In line with theses findings, TGF-beta 1 + IFN-gamma-conditioned media led to a lower Ly6C(low)/Ly6C(high) monocyte migration ratio compared to sole TGF-beta 1 treatment. These differences in monocyte migration reflect the complex interplay of pro-inflammatory cytokines and pro-fibrotic factors in cardiac remodelling and inflammation.
