Subject(s)
Cardiovascular Diseases/prevention & control , Drinking/physiology , Exercise/physiology , Lactates/metabolism , Muscle, Smooth, Vascular/physiology , Animals , Cardiovascular Diseases/etiology , Female , Heart Function Tests , Humans , Hypertension/complications , Lactates/blood , Male , Mitochondria, Muscle/metabolism , Mitochondria, Muscle/physiology , Muscle, Smooth, Vascular/metabolism , Myocardial Contraction/physiology , Rats , Sensitivity and SpecificityABSTRACT
Non-specific markers of inflammation such as C-reactive protein (CRP) are associated statistically with an increased risk of atherosclerosis through mechanisms that have not yet been fully elucidated. We investigated the effects of CRP on several aspects of human monocyte biology, a cell type involved in the initiation and progression of atherosclerosis. Blood monocytes isolated from healthy men and premenopausal women (n = 9/group) were exposed to purified CRP (25 microg/ml) for 12 hours. Changes in gene expression were analyzed using a custom-made array containing oligonucleotide sequences of 250 genes expressed by activated monocytes and confirmed by quantitative PCR. CRP increased significantly the expression of the cytokines interleukin (IL)-1alpha, IL-1beta and IL-6, and the chemokines GRO-alpha, GRO-beta and IL-8. CRP also displayed anti-inflammatory effects through upregulation of liver X receptor (LXR) alpha and activin receptor expression, and down-regulation of alpha 2-macroglobulin expression. Increased LXRalpha mRNA expression in both monocytes and the monocytic cell lineTHP-1 was associated with increased LXRalpha protein expression and nuclear translocation, as well as increased ABCA1 mRNA expression, a target gene of LXRalpha. Western blot analysis revealed CRP-induced nuclear translocation of NF-kappaB and activation of p42/44, MAP and Akt kinases. CRP-induced LXRalpha mRNA expression was inhibited by anti-CD64 (FcgammaRI) antibodies and by p42/44 and PI3 kinase inhibitors. This hypothesis-generating study demonstrates that CRP modulates the expression of genes that contribute to both pro- and anti-inflammatory responses in human monocytes. Among these novel anti-inflammatory effects, we show clearly that CRP activates the LXRalpha pathway.
Subject(s)
Atherosclerosis/metabolism , C-Reactive Protein/metabolism , Cytokines/metabolism , DNA-Binding Proteins/metabolism , Gene Expression Regulation , Inflammation Mediators/metabolism , Inflammation/metabolism , Monocytes/metabolism , Receptors, Cytoplasmic and Nuclear/metabolism , Adult , Atherosclerosis/genetics , Atherosclerosis/prevention & control , Cell Line, Tumor , Cells, Cultured , Cytokines/genetics , DNA-Binding Proteins/genetics , Female , Gene Expression Profiling/methods , Humans , Inflammation/genetics , Inflammation/prevention & control , Lipopolysaccharide Receptors/analysis , Liver X Receptors , Male , Monocytes/immunology , Oligonucleotide Array Sequence Analysis , Orphan Nuclear Receptors , RNA, Messenger/metabolism , Receptors, Cytoplasmic and Nuclear/genetics , Recombinant Proteins/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Sex Factors , Signal Transduction/genetics , Time Factors , Up-RegulationABSTRACT
C-reactive protein (CRP) is an independent predictor of atherosclerosis and its complications. Monocytes/macrophages are implicated in this complex disease which is, among other mechanisms, characterised by angiogenesis. The aim of this study was to analyse whether CRP plays a role in VEGF-A regulation by monocytic cells. Our findings show that CRP up-regulates VEGF-A mRNA expression and protein excretion in THP-1 cells in a concentration- and time-dependent manner. Furthermore, we studied the signaling pathway underlying this effect. CRP increases VEGF-A expression via a PI3-kinase and an extracellular-signal-regulated kinase (ERK) 1/2 dependent pathway. Our results suggest that CRP could play a role in the angiogenesis process via immune cells such as monocytes.
Subject(s)
C-Reactive Protein/metabolism , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/metabolism , Monocytes/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Vascular Endothelial Growth Factor A/metabolism , Enzyme Inhibitors/pharmacology , Humans , MAP Kinase Signaling System , Neovascularization, Pathologic , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction , Time Factors , p38 Mitogen-Activated Protein Kinases/metabolismABSTRACT
Recently, we demonstrated that boron modulates the turnover of the extracellular matrix and increases TNFalpha release. In the present study, we used an in vitro test to investigate the direct effect of boron on specific enzymes (elastase, trypsin-like enzymes, collagenase and alkaline phosphatase) implicated in extracellular matrix turnover. Boron decreased the elastase and alkaline phosphatase activity, but had no effect on trypsin and collagenase activities. The effect of boron on the enzyme activities was also tested in fibroblasts considered as an in vivo test. In contrast to the results obtained in vitro, boron enhanced the trypsin-like, collagenase, and cathepsin D activities in fibroblasts. Boron did not modify the generation of free radicals compared to the control and did not seem to act on the intracellular alkaline phosphatase activity, However, as it did enhance phosphorylation, it can be hypothesized that boron may affect living cells via a mediator, which could be TNFalpha whose transduction signal involves a cascade of phosphorylations.
