ABSTRACT
Bradykinin (BK), a vasoactive, proinflammatory nonapeptide, promotes cell adhesion molecule (CAM) expression, leukocyte sequestration, inter-endothelial gap formation, and protein extravasation in postcapillary venules. These effects are mediated by bradykinin-1 (B1R) and-2 (B2R) receptors. We delineated some of the mechanisms by which BK could influence chronic inflammation by altering CAM expression on leukocytes, endothelium, and synovium in joint sections of peptidoglycan-polysaccharide-injected Lewis rats. Blocking B1R results in significantly increased joint inflammation. Immunohistochemistry of the B1R antagonist group revealed increased leukocyte and synovial CD11b and CD54 expression and increased CD11b and CD44 endothelial expression. B2R antagonism decreased leukocyte and synovial CD44 and CD54 and endothelial CD11b expression. Although these findings implicate B2R involvement in the acute phase of inflammation by facilitating leukocyte activation (CD11b), homing (CD44), and transmigration (CD54). Treatment with a B2R antagonist did not affect the disease evolution in this model. In contrast, when both BK receptors are blocked, the aggravation of inflammation by B1R blockade is neutralized and there is no difference from the disease-untreated model. Our findings suggest that B1R and B2R signaling show physiologic antagonism. B1R signaling suggests involvement in down-regulation of leukocyte activation, transmigration, and homing. Further studies are needed to evaluate the B1 receptor agonist's role in this model.
Subject(s)
Arthritis/metabolism , Bradykinin/physiology , Cell Adhesion Molecules/biosynthesis , Endothelium, Vascular/drug effects , Leukocytes/drug effects , Synovial Membrane/drug effects , Animals , Arthritis/chemically induced , Arthritis/genetics , Arthritis, Rheumatoid/metabolism , Bradykinin/analogs & derivatives , Bradykinin/biosynthesis , Bradykinin/genetics , Bradykinin/pharmacology , Bradykinin B1 Receptor Antagonists , Bradykinin B2 Receptor Antagonists , CD11b Antigen/biosynthesis , CD11b Antigen/genetics , Cell Adhesion/drug effects , Cell Adhesion Molecules/genetics , Chemotaxis, Leukocyte/drug effects , Disease Models, Animal , Endothelium, Vascular/pathology , Female , Gene Expression Regulation/drug effects , Hyaluronan Receptors/biosynthesis , Hyaluronan Receptors/genetics , Intercellular Adhesion Molecule-1/biosynthesis , Intercellular Adhesion Molecule-1/genetics , L-Selectin/biosynthesis , L-Selectin/genetics , Leukocytes/metabolism , Male , Oligopeptides/pharmacology , Peptidoglycan/toxicity , Prekallikrein/analysis , Rats , Rats, Inbred Lew , Receptor, Bradykinin B1/physiology , Receptor, Bradykinin B2/physiology , Specific Pathogen-Free Organisms , Synovial Membrane/blood supply , Synovial Membrane/metabolism , Synovial Membrane/pathologyABSTRACT
Previously we demonstrated that domain 5 (D5) of high-molecular-weight kininogen (HK) inhibits neovascularization in the chicken chorioallantoic membrane (CAM) assay and further found that kallikrein cleaved HK (HKa) inhibited FGF2-and VEGF-induced neovascularization, and thus was antiangiogenic. In this study, we sought to demonstrate whether uncleaved HK stimulates neovascularization and thus is proangiogenic. The chick chorioallantoic membrane was used as an in ovo assay of angiogenesis. Low-molecular-weight kininogen stimulates angiogenesis, indicating that D5 is not involved. Bradykinin stimulates neovascularization equally to HK and LK and is likely to be responsible for the effect of HK. A murine monoclonal antibody to HK (C11C1) also recognizes a similar component in chicken plasma as detected by surface plasmon resonance. Angiogenesis induced by FGF2 and VEGF is inhibited by this monoclonal antibody and is a more potent inhibitor of neovascularization induced by VEGF than an integrin alphavbeta3 antibody (LM 609). Our postulate that C11C1 inhibits the stimulation of angiogenesis by HK was confirmed when either C11C1 or D5 completely inhibited angiogenesis in the CAM induced by HK. Growth of human fibrosarcoma (HT-1080) on the CAM was inhibited by GST-D5 and C11C1. These results indicate HK is proangiogenic probably by releasing bradykinin and that a monoclonal antibody directed to HK could serve as an antiangiogenic agent with a potential for inhibiting tumor angiogenesis and other angiogenesis-mediated disorders.
