title: C-reactive protein augments interleukin-8 secretion in human peripheral blood monocytes.
abstract: C-reactive protein (CRP) is a powerful predictor and risk factor for cardiovascular diseases. The CXC- and CC-type chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) are important chemokines for leukocyte trafficking identified in atheromatous plaque expressed mainly by macrophages in humans. We assessed whether C-reactive protein could induce MCP-1 and IL-8 secretion. In human peripheral blood monocytes, C-reactive protein (12.5-50 microg/mL) increased IL-8, but not MCP-1 secretion in a time- (6-24 hours) and dose-dependent manner as detected by ELISA. C-reactive protein could augment the production of reactive oxygen species (ROS) as measured by chemiluminescence and inhibitors of NAD(P)H oxidase (DPI and PAO) and ROS scavengers (superoxide dismutase, catalase, and 1% dimethyl sulphoxide) abolished C-reactive protein-induced IL-8 secretion. Furthermore, relative quantity of IL-8 mRNA was significantly increased by C-reactive protein 50 microg/mLfor 12 hours, which could be inhibited by DPI 1 microM or superoxide dismutase (SOD) 250 U/mL. The inhibitors of ERK 1/2 (PD98059), p38 (SB203580) MAPK, and NF-kappaB (PDTC and MG132) significantly decreased C-reactive protein-induced IL-8 secretion in human monocytes. Also, agonists of peroxisome proliferator-activated receptor (PPAR) alpha (WY14643) and PPARgamma (troglitazone) could largely inhibit C-reactive protein responses. Thus, our data indicate that C-reactive protein at pathologic levels increases IL-8 secretion and mRNA via enhancing ROS derived mainly from NAD(P)H oxidase and the subsequent activation of ERK1/2, p38 MAPK, and NF-kappaB. The activation of PPARalpha/gamma can negatively regulate C-reactive protein-induced IL-8 production in human monocytes.
authors.affiliation: Department of Physiology and Key Laboratory of Molecular Cardiovascular Science of Education Ministry, Basic Medical College, Peking University, Beijing 100-083, China.
authors.forename: Liangqi
authors.initials: L
authors.lastname: Xie
authors.forename: Lina
authors.initials: L
authors.lastname: Chang
authors.forename: Youfei
authors.initials: Y
authors.lastname: Guan
authors.forename: Xian
authors.initials: X
authors.lastname: Wang
mesh_terms: D002097:C-Reactive Protein / Q000494:pharmacology*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D018932:Chemokine CCL2; D016209:Interleukin-8; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D002097:C-Reactive Protein