title: Tumor necrosis factor alpha stimulates cathepsin K and V activity via juxtacrine monocyte-endothelial cell signaling and JNK activation.
abstract: Inflammation and damage promote monocyte adhesion to endothelium and cardiovascular disease (CVD). Elevated inflammation and increased monocyte-endothelial cell interactions represent the initial stages of vascular remodeling associated with a multitude of CVDs. Cathepsins are proteases produced by both cell types that degrade elastin and collagen in arterial walls, and are upregulated in CVD. We hypothesized that the inflammatory cytokine tumor necrosis factor alpha (TNFα) and monocyte binding would stimulate cathepsins K and V expression and activity in endothelial cells that may be responsible for initiating local proteolysis during CVD. Confluent human aortic endothelial cells were stimulated with TNFα or THP-1 monocyte co-cultures, and multiplex cathepsin zymography was used to detect changes in levels of active cathepsins K, L, S, and V. Direct monocyte-endothelial cell co-cultures stimulated with TNFα generated maximally observed cathepsin K and V activities compared to either cell type alone (n = 3, p < 0.05) by a c-Jun N-terminal kinase (JNK)-dependent manner. Inhibition of JNK with SP6000125 blocked upregulation of cathepsin K activity by 49 % and cathepsin V by 81 % in endothelial cells. Together, these data show that inflammatory cues and monocyte-endothelial cell interactions upregulate cathepsin activity via JNK signaling axis and identify a new mechanism to target toward slowing the earliest stages of tissue remodeling in CVD.
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Keegan
authors.forename: Catera L
authors.initials: CL
authors.lastname: Wilder
authors.forename: Manu O
authors.initials: MO
authors.lastname: Platt
mesh_terms: D000873:Anthracenes / Q000494:pharmacology; D056657:Cathepsin K / Q000378:metabolism*; D002403:Cathepsins / Q000378:metabolism*; D002448:Cell Adhesion; D002450:Cell Communication; D002460:Cell Line; D018920:Coculture Techniques; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D042783:Endothelial Cells / Q000201:enzymology*; D004789:Enzyme Activation; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D009000:Monocytes / Q000502:physiology*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology*
chemical_list: D000873:Anthracenes; D014409:Tumor Necrosis Factor-alpha; C432165:pyrazolanthrone; D051057:Proto-Oncogene Proteins c-akt; D048670:MAP Kinase Kinase 4; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C534130:CTSK protein, human; D056657:Cathepsin K; C117627:CTSV protein, human