C-Reactive Protein Does Not Directly Induce Tissue Factor in Human Monocytes

Abstract

Objective-It is generally assumed that C-reactive protein (CRP) induces synthesis of tissue factor (TF) in monocytic cells, thereby potentially initiating intravascular blood coagulation. We aimed to elucidate the mechanism of CRP-induced TF expression in monocytes and monocyte-derived macrophages (MDMs) in vitro. Methods and Results-Monocytes were isolated from the blood of healthy donors and cultured with or without CRP or lipopolysaccharide (LPS) to study the time course of TF antigen and TF mRNA expression. Addition of 100 g/mL CRP did not result in a significant increase in TF antigen (range: 9 to 163 pg/10 6 cells, nϭ11) and TF mRNA (relative number of TF transcripts; N TF ϭ0.01 to 0.33), when compared with nonstimulated cells (TF antigen 7 to 46 pg/10 6 cells, N TF ϭ0.01 to 0.13). Variation of CRP concentration and exposure time did not affect the TF response. Similar results were obtained in monocytes cultured in suspension and in MDMs. In contrast, TF was strongly induced by 10 g/mL LPS (TF antigen 1125 to 6120 pg/10 6 cells, N TF ϭ5.94 to 23.43). Cultured monocytes did express FcR␥II, a putative CRP receptor, and addition of CRP induced a 7-fold increase in the production of monocyte chemoattractant protein-1 (MCP-1). Interestingly, CRP addition to peripheral blood mononuclear cells (PBMCs) did result in TF expression on monocytic cells. Conclusions-The

C-Reactive Protein is not an Independent Risk Factor for Ventricular Thrombus

“…However an experimental study by Paffen et al contradicts this claim. 4 Our clinical observations are consistent with this view.…”

“…2 CRP promotes innate immunity by binding complement factor C1q to activate the classical complement pathway. 4 Elevated CRP levels have been found to correlate with higher risk for future adverse cardiac events in patients with acute myocardial infarction 5,6 stable and unstable coronary artery disease. 7,8 and peripheral arterial reconstruction 9 CRP is an independent predictor of cardiovascular risk.…”

Serum Amyloid A Induces Monocyte Tissue Factor

“…Cell-mediated immunity via cytokines originating from lymphocytes and direct monocyte-lymphocyte interaction via CD40 ligation are known to participate in the process (18,41). We and others demonstrated that lymphocytes are absolutely required for monocyte TF induction by CRP, and contribute, in part, to LPS induction of monocyte TF (19,42). Depletion of lymphocytes from PBMC reduced SAA and LPS-induced PCA by ϳ50%, indicating that lymphocytes contribute to optimal TF induction by SAA.…”

“…Soluble RAGE [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] (sRAGE) and the reverse peptide were synthesized by manual solid-phase synthesis using 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate-mediated couplings with Boc in situ neutralization chemistry (27) and purified by preparative reverse-phase HPLC using a C 18 column. Fractions containing the pure proteins were rerun on analytical HPLC, and masses were confirmed by electrospray ionization mass spectrometry (21,765.5 Ϯ 1.0, calculated: 2,177.2).…”

“…To determine whether induction may occur via RAGE, SAA or LPS was preincubated with sRAGE [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] peptide antagonist containing the RAGE ligand-binding domain, and PBMC was stimulated 2 h later. Fig.…”