Human cardiac fibroblasts express ICAM-1, E-selectin and CXC chemokines in response to proinflammatory cytokine stimulation

Neutrophil attraction and adhesion to endothelial cells occurs via well defined mechanisms, yet the ability of other cell types to express neutrophil-binding adhesion molecules is not well studied. Cardiac fibroblasts (CF) are a key cell type involved in repair of the infarcted myocardium, a scenario in which neutrophil recruitment is perceived to be detrimental. Here we determined the effects of proinflammatory cytokines on expression of neutrophil-binding adhesion molecules and neutrophil-attracting chemokines in CF cultured from multiple patients, and explored the underlying regulatory mechanisms. An adhesion molecule focused RT-PCR array identified 5 transcripts that were increased markedly in human CF treated with the proinflammatory cytokine interleukin-1 (IL-1, 10 ng/ml, 6 h); including intercellular cell adhesion molecule (ICAM-1) and E-selectin. Real-time RT-PCR verified the array data and immunoblotting confirmed cytokine-induced ICAM-1 and E-selectin protein expression. Treatment with a panel of pharmacological inhibitors identified the NF-κB pathway as mediating IL-1-induced ICAM-1 and E-selectin mRNA and protein expression. Additionally, E-selectin expression in human CF was markedly potentiated by the JNK inhibitor SP600125, but this was not observed when a more selective inhibitor ((L)-JNKI-1) was used, or in human vascular endothelial cells. IL-1 also stimulated CF to secrete the neutrophil chemoattractant CXCL8 via a p38- and NF-κB-dependent mechanism, as well as inducing CXCL1, CXCL2 and CXCL5 mRNA expression. In conclusion, human CF express neutrophil-binding adhesion molecules and neutrophil chemoattractants in response to proinflammatory cytokines suggesting that, in addition to EC, CF may play an important role in regulating neutrophil recruitment into the infarcted myocardium.