Abstract P266: Molecular Markers of Endothelial Sensitivity to TNFα
TNF alpha mediated inflammation has been correlated with cardiovascular diseases. Significant interindividual variability to anti-TNF biologicals has been demonstrated in clinical trials. The objective of this study is to unravel the molecular markers of sensitivity to TNF which could be used as predictors of therapeutic efficacy or disease progression. We have isolated and tested a set of 20 HUVECs for their sensitivity to TNF as determined by up-regulation of pro-inflammatory genes such as the Intracellular Adhesion Molecule 1 (ICAM1) and the NADPH oxidase subunit 4 (NOX4). We found that 75% of HUVECs (15/20) responded strongly to TNF compared to the remaining 25% (5/20, p<0.01). Further studies on the TNF signaling pathway indicated that there was a positive correlation between strong response to TNF and higher basal mRNA and protein levels of the mitogen activated protein 3 kinase 1 (MAP3K1 or MEKK1). No further correlations where observed with other signaling components (i.e., TNF receptors, TRAFs, and other MAP3Ks, MAP2Ks or MAPKs). Strong responders also showed 1) increased upregulation of TNFR1 and TRAF5 protein and mRNA levels, 2) higher phosphorylation of JNK and p38 MAPKs and 3) stronger AP1-driven transcription as shown by luciferase assays. Weak responders showed increased TNF-dependent down-regulation of the TNF receptor 1 and of the MAP3K5 (aka Apoptosis-Signaling Kinase 1, ASK1) and TNF-mediated upregulation of the TNF receptor 2 compared to strong responders. Promoter and mRNA stability studies revealed that differences between strong and weak responders in MAP3K1 and MAP3K5 regulation occurs at the transcriptional level. Studies of promoter polymorphisms are undergoing. We conclude that MAP3K1 and MAP3K5 are novel molecular markers of endothelial sensitivity to TNF and future studies on these genes could reveal novel genetic markers for translational research.
- © 2011 by American Heart Association, Inc.