Plasma Kallikrein-kinin System Research Articles

A Role for Activation of the Kallikrein-Kinin System in the Homing Property of Endothelial Progenitor Cells.

The plasma kallikrein–kinin system (KKS) plays an important role in inflammation, thrombosis and vascular pathology. Activation of the KKS results in bradykinin release, which increases vascular permeability and modulates inflammatory responses. Circulating endothelial progenitor cells (EPCs) home to ischemic and inflamed tissues and participate in the vasculogenesis. However, the homing mechanism remains poorly understood. We now report that activation of the KKS regulates the homing property of EPCs using in vivo and in vitro approaches. We have previously shown that the Lewis rat, which displays a mutant kininogen (Ser511Ala), is susceptible to peptidoglycan-polysaccharide (PG-PS)- induced systemic inflammation including arthritis and displays activation of the KKS and increased bradykinin levels. CD34-positive EPCs were isolated from bone marrow of disease-free Lewis rats by Ficoll gradient centrifugation. After culture in EGM2 on collagen surfaces for 7 days, a single colony with cobblestone-like morphology appeared and was subjected to large-scale expansion. Compared with differentiated rat lung microvessel endothelial cells (rLMECs), rat EPCs expressed similar levels of endothelial cell lineage marker mRNA such as VE-cadherin, CD31, vWF and uPAR. EPCs exclusively expressed hematopoietic progenitor cell markers, Sca-1 and CD34. Both of EPCs and rLMECs expressed bradykinin type 2 receptor (B2R) but not B1R. To observe the in vivo mobilization of EPCs, EPCs were labeled with carboxyfluorescein diacetate, succinimidyl ester (CFDA-SE) and injected into Lewis rats in which inflammation/arthritis was induced by PG-PS. Two weeks after PG-PS injection, pannus formed in the synovial tissues, representing the entry into the chronic phase of arthritis. The fluorescently-labeled EPCs were selectively detected in the inflamed synovium of PG-PS-treated rats, but not that of disease-free rats. As detected by confocal microscopy, implanted EPCs formed new blood vessels in the inflamed synovial tissues. To further investigate the mechanism by which the KKS regulates EPC mobilization, we observed that bradykinin (a B2R agonist), but not des-Arg9-bradykinin (a B1R agonist), stimulated EPC transmigration through confluent rLMEC layer at 100 and 1000 nM (P<0.01 and P<0.001, respectively). Bradykinin did not affect EPC adhesion to rLMECs. Priming by tumor necrosis factor a (TNFa), a major inflammatory cytokine, induced transendothelial migration of EPCs by 100 nM des-Arg9- bradykinin (168.56 ± 9.56 vs 96.02 ± 10.23, P<0.001). The priming effect resulted from TNFa induction of B1R mRNA. As determined by RT-PCR, rat EPCs expressed mRNA of multiple homing receptors including chemokine (C-X-C motif) receptor 4, CD49d and CD62-E, but not CD11a. Thus, activation of the KKS regulates the homing property of EPCs, which constitutes an additional mechanism for involvement of the KKS in the vasculogenesis. B2R predominantly mediates transendothelial migration of normal EPCs, whereas B1R seems responsible for that of inflamed EPCs. Kinins and cytokines such as TNFa may synergize to regulate the mobilization of EPCs. These observations provide a new insight into understanding the role of the KKS in vascular pathology and inflammation.

Deletion of murine kininogen gene 1 (mKng1) causes loss of plasma kininogen and delays thrombosis

AbstractHigh-molecular-weight kininogen (HK) plays an important role in the assembly of the plasma kallikrein-kinin system. While the human genome contains a single copy of the kininogen gene, 3 copies exist in the rat (1 encoding K-kininogen and 2 encoding T-kininogen). Here, we confirm that the mouse genome contains 2 homologous kininogen genes, mKng1 and mKng2, and demonstrate that these genes are expressed in a tissue-specific manner. To determine the roles of these genes in murine development and physiology, we disrupted mKng1, which is expressed primarily in the liver. mKng1−/− mice were viable, but lacked plasma HK and low-molecular-weight kininogen (LK), as well as ΔmHK-D5, a novel kininogen isoform that lacks kininogen domain 5. Moreover, despite normal tail vein bleeding times, mKng1−/− mice displayed a significantly prolonged time to carotid artery occlusion following Rose Bengal administration and laser-induced arterial injury. These results suggest that a single gene, mKng1, is responsible for production of plasma kininogen, and that plasma HK contributes to induced arterial thrombosis in mice.

Identification of lipopolysaccharide binding site on high molecular weight kininogen

Plasma kallikrein kinin system (KKS) activation along with its cellular receptors expression are increased after injury and in patients with septic shock, hypotensive bacteremia and rhesus monkey infected with Salmonella typhimurium. KKS signaling cascade is activated by activated factor XII (FXIIa, Hageman factor)- and prolylcarboxypeptidase (PRCP)-dependent pathways on endothelial cells. Among the many entities that comprise the KKS, high molecular weight kininogen (HK), a bradykinin precursor, is critical in the assembly and activation of this system. HK is primarily expressed in the liver and secreted into the bloodstream. The activation of the KKS influences the permeability of the endothelium by liberating bradykinin (BK) from HK. BK is a potent inflammatory peptide which stimulates constitutive bradykinin B2 and inducible B1 receptors to release nitric oxide and prostacyclin. Regardless of the triggers, PK can only be activated on HK bound to the artificial negatively charged or to cell membrane surfaces. Since LPS has a negatively charged moiety and the ability to induce inflammatory responses in human, we determined the interaction between LPS and HK. HKH19 (HK cell binding site) and heparin inhibited LPS binding to HK with IC 50s of 15 nM and 20 μg/ml, respectively. C1-inhibitor and N-acetylglucosamine glycan inhibited LPS binding to HK with IC 50s of about 10 μg/ml and 10 mM, respectively. This novel study underscores the implication of HK in infection. We propose that HKH19, heparin, and C1-inhibitor present therapeutic potential for the treatment of sepsis and hypotensive bacteremia.

Deletion of Murine Kininogen Gene 1 (mKNG1) Causes Loss of Plasma Kininogen and Delays Thrombosis.

High molecular weight kininogen (HK) plays an important role in the assembly of the plasma kallikrein-kinin system. While the human genome contains a single copy of the kininogen gene, three copies exist in the rat (one encoding K-kininogen and two encoding T-kininogen). Here, we confirm that the mouse genome contains two homologous kininogen genes, mKng1 and mKng2. These genes are located on chromosome 16 in a head to head orientation with ∼ 30 kB intervening sequence, and are expressed in a tissue-specific manner. To determine the roles of these genes in murine development and physiology, we disrupted mKng1, which is expressed primarily in the liver. mKng1−/ − mice were viable, and immunoblotting using anti-bradykinin antibodies indicated a marked reduction in plasma HK and low molecular weight kininogen (LK), as well as ΔmHK-D5, a novel kininogen isoform that lacks kininogen domain 5. Clotting studies were also consistent with marked HK deficiency. Moreover, despite normal tail vein bleeding times, mKng1−/− mice displayed a significantly prolonged time to carotid artery occlusion following Rose Bengal administration and laser induced arterial injury. These results suggest that a single gene, mKng1, is responsible for production of plasma kininogen, and that plasma high molecular weight kininogen may contribute to induced arterial thrombosis in mice.

Cleaved High Molecular Weight Kininogen (HKa) and Kininostatin (D5) Induce Apoptosis and Inhibit Migration and Invasion of Human Prostate Cancer Cells by Preventing AKT Phosphorylation and Cyclin D1 Synthesis and Disrupting the Interaction of UPAR and EGFR.

Tumor metastasis is a major factor in the mortality rate in human prostate cancer. Upregulation and activation of EGFR and/or uPAR in a variety of cancers have been shown to be associated with poor prognosis. HK, a component of the plasma kallikrein-kinin system, can be hydrolyzed by plasma kallikrein to bradykinin and HKa. HKa and D5 both have been demonstrated to have potent anti-angiogenic activity in vitro and in vivo. We previously published that D5 directly inhibits human colon carcinoma cell (HCT-116) proliferation in vitro by blocking the G1/S transition in the cell cycle. We now show that HKa [100 nM] inhibits the migration of human prostate tumor cell (DU145) about 50%. Cyclin D1 can activate p21 and p27 with concomitant cell migration. DU145 cells rapidly increase cyclin D1 synthesis in response to bFGF [1.2 nM]. HKa suppresses cyclin D1 expression as shown by Western blotting as well as cell immunoflourescence. Stimulation by bFGF or VEGF results in clustering of uPAR and EGFR on the surface of DU145 cells. Immunoflourescence shows that the addition of HKa disrupts the co-localization of uPAR and EGFR. HKa or a monoclonal antibody against uPAR decreases the phosphorylation of EGFR at Tyr 1173. The phosphorylation of ERK and AKT, which are downstream effectors of EGFR, is also inhibited by HKa. Kininostatin [300nM] induced apoptosis of human prostate cancer cells challenged with uPA [50 nM] or EGF [6.7 nM]. Matrigel invasion assay reveals that HKa [100 nM] decreases the invading cell number by 90%. These novel data indicate that HKa and kininostatin induce apoptosis and inhibit migration and invasion of human prostate cancer cells, indicating the therapeutic potential of kininostatin in metastasis human prostate cancer.

Ca2+ signalling of kinins in cells expressing rat, mouse and human B1/B2-receptor

With respect to functional aspects, the kallikrein–kinin-system can be divided into a plasma kallikrein–kinin-system and a tissue kallikrein–kinin-system. At least four functional kinin peptides act via two different G-protein-coupled receptors, an inducible B1-receptor and a constitutively expressed B2-receptor. B1R and B2R couple to Gq/11 and lead via phospholipase C to Ca2+ mobilization. In humans both, bradykinin and kallidin are agonists on the B2-receptor. In contrast, bradykinin is believed to be the only kinin acting on the B2R in rats and mice. However, recently we have isolated a kallidin-like-peptide from plasma and urine of rats.Until now the kinin ligand–receptor interactions were mainly characterized in binding studies. However, receptor affinity does not inevitably correspond with the intrinsic activity of an agonist.The aim of the present study was to investigate intracellular calcium mobilization to quantify mouse, rat and human B1- and B2-receptor activation by bradykinin, kallidin, des-Arg9-bradykinin, des-Arg10-kallidin, and of the two novel rat kinins, kallidin-like-peptide and des-Arg10-kallidin-like-peptide.In cells stably expressing the human, rat, and mouse B2-receptor, respectively, bradykinin, kallidin, and kallidin-like-peptide were nearly equipotent (EC50, 10−12M) at eliciting Ca2+-transients. Their des-Arg-derivatives were 103-fold less potent.In cells expressing B1-receptor the des-Arg derivatives elicited Ca2+-signals at an EC50 in the order of 10−9M. Major differences between these peptides could not be observed. Bradykinin, kallidin, and kallidin-like-peptide caused a Ca2+-signal at substantially higher concentrations in the order of 10−7M.The data show that des-Arg9-bradykinin, des-Arg10-kallidin, and des-Arg10-kallidin-like-peptide are equipotent agonists at the B1-receptor. Bradykinin, kallidin and kallidin-like-peptide are equipotent agonists at the B2-receptor.

The plasma kallikrein-kinin system: its evolution from contact activation.

The plasma kallikrein-kinin system consists of the proteins factor XII (FXII), prekallikrein (PK), and high molecular weight kininogen. It was first recognized as a surface-activated coagulation system that is activated when blood or plasma interacts with artificial surfaces. Although surface-activated contact activation occurs in vivo in the case of tissue destruction or a developing thrombus, the physiologic basis for the activation and function of this system has not been delineated. New investigations indicate that there is a proteolytic pathway on cells for PK activation independent of FXII. This pathway for PK with subsequent FXII activation indicates physiologic activities. These activities include blood pressure regulation and modulation of thrombosis risk independently of hemostasis. Furthermore, they include regulation of endothelial cell proliferation, angiogenesis and apoptosis through a cellular-based, outside-in signaling system. The present characterizations of this system, which incorrectly had been thought to initiate coagulation, represent an evolution of understanding in this field.

Identification and characterization of plasma kallikrein–kinin system inhibitors from salivary glands of the blood‐sucking insect Triatoma infestans

Two plasma kallikrein-kinin system inhibitors in the salivary glands of the kissing bug Triatoma infestans, designated triafestin-1 and triafestin-2, have been identified and characterized. Reconstitution experiments showed that triafestin-1 and triafestin-2 inhibit the activation of the kallikrein-kinin system by inhibiting the reciprocal activation of factor XII and prekallikrein, and subsequent release of bradykinin. Binding analyses showed that triafestin-1 and triafestin-2 specifically interact with factor XII and high molecular weight kininogen in a Zn2+-dependent manner, suggesting that they specifically recognize Zn2+-induced conformational changes in factor XII and high molecular weight kininogen. Triafestin-1 and triafestin-2 also inhibit factor XII and high molecular weight kininogen binding to negatively charged surfaces. Furthermore, they interact with both the N-terminus of factor XII and domain D5 of high molecular weight kininogen, which are the binding domains for biological activating surfaces. These results suggest that triafestin-1 and triafestin-2 inhibit activation of the kallikrein-kinin system by interfering with the association of factor XII and high molecular weight kininogen with biological activating surfaces, resulting in the inhibition of bradykinin release in an animal host during insect blood-feeding.

The plasma kallikrein-kinin system and risk of cardiovascular disease in men.

The plasma kallikrein-kinin system (PKKS) has been implicated in cardiovascular disease, but activation of the PKKS has not been directly probed in individuals at risk of coronary heart disease (CHD) or stroke. To determine the involvement of the PKKS, including factor XI, in cardiovascular disease occurring in a nested case-control study from the Second Northwick Park Heart Study (NPHS-II). After a median follow-up of 10.7 years, 287 cases of CHD and stroke had been recorded and 542 age-matched controls were selected. When FXIIa-C1 esterase inhibitor (C1-inhibitor) concentrations were divided into tertiles (lowest tertile as reference), the odds ratios (ORs) at 95% CIs for CHD were 0.52 (0.34-0.80) in the middle tertile and 0.73 (0.49-1.09) in the highest tertile (P = 0.01 for the overall difference; P = 0.01 for CHD and stroke combined). For kallikrein-C1-inhibitor complexes, the ORs for stroke were 0.29 (0.12-0.72) and 0.67 (0.30-1.52) in the middle and high tertiles, respectively (P = 0.02). FXIIa-C1-inhibitor and kallikrein-C1-inhibitor complexes were negatively related to smoking and fibrinogen (P < 0.005). FXIa-inhibitor complexes correlated strongly with FXIIa-inhibitor complexes. Lower levels of inhibitory complexes of the PKKS enzymes and particularly of FXIIa contribute to the risk of CHD and stroke in middle-aged men. This observation supports the involvement of the PKKS in atherothrombosis.

Myeloperoxidase Interacts with Endothelial Cell-Surface Cytokeratin 1 and Modulates Bradykinin Production by the Plasma Kallikrein-Kinin System

During an inflammatory state, functional myeloperoxidase (MPO) is released into the vessel as a result of intravascular neutrophil degradation. One mechanism of resulting cellular injury involves endothelial internalization of MPO, which causes oxidative damage and impairs endothelial signaling. We report the discovery of a protein that facilitates MPO internalization, cytokeratin 1 (CK1), identified using affinity chromatography and mass spectrometry. CK1 interacts with MPO in vitro, even in the presence of 100% human plasma, thus substantiating biological relevance. Immunofluorescent microscopy confirmed that MPO added to endothelial cells can co-localize with endogenously expressed CK1. CK1 acts as a scaffolding protein for the assembly of the vasoregulatory plasma kallikrein-kinin system; thus we explored whether MPO and high molecular weight kininogen (HK) reside on CK1 together or whether they compete for binding. The data support cooperative binding of MPO and HK on cells such that MPO masked the plasma kallikrein cleavage site on HK, and MPO-generated oxidants caused inactivation of both HK and kallikrein. Collectively, interactions between MPO and the components of the plasma kallikrein-kinin system resulted in decreased bradykinin production. This study identifies CK1 as a facilitator of MPO-mediated vascular responses and thus provides a new paradigm by which MPO affects vasoregulatory systems.

Fifty years of research on the plasma kallikrein-kinin system: From protein structure and function to cell biology and in-vivo pathophysiology

Fifty years of research on the plasma kallikrein-kinin system: From protein structure and function to cell biology and in-vivo pathophysiology -

Contribution of Coagulation Pathways and Fibrinolysis in Generation of Kinins.

BACKGROUND. Classically, there are two main pathways by which kinins are generated: the plasma and tissue kallikrein-kinin systems. Each of this complex multi-protein system includes tissue or plasma kallikrein, which generate kinins from high or low molecular weight kininogen. In addition to plasma and tissue kallikreins, other serine proteases may have a kinin-forming capacity.OBJECTIVES. The main purpose of this study was to characterize the kininogenase activity of plasma kallikrein, thrombin (factor IIa), factor Xa, and plasmin in a purified system. We also aimed at characterizing the kinetic profile of generation of kinins in a whole blood system where coagulation and fibrinolysis were monitored by thromboelastography.METHODS. Bradykinin (BK) released from both low and high molecular weight kininogens and quantified with a specific competitive enzyme immunoassay was used to calculate the kinetic parameters for the different kininogenase activities. Physicochemical and pharmacological characterization of immunoreactive kinins confirm their nature. The kinetic profile of kinin generation was studied during the process of coagulation which was initiated with kaolin or with tissue factor and monitored by thromboelastography.RESULTS. BK was released not only by plasma kallikrein; both plasmin and factor Xa hydrolyzed high molecular kininogen to produce BK. In the case of thrombin, the release of both BK and kallidin was detected from low and high molecular weight kininogen. When applied to whole blood, this analytical approach indicated that the kinin-forming capacity of the coagulation intrinsic pathway was higher than that of the extrinsic pathway. The triggering of fibrinolysis by tissue plasminogen activator dramatically potentiated the release of des-Arg9-BK.CONCLUSIONS. Although plasma kallikrein is considered as being the main kinin-forming enzyme, other serine proteases of the coagulation and the fibrinolysis pathways are able to generate kinins and could play a role in different pathologies where kinins are potentially involved.

Mediator Responses in Surgical Infections

Surgical infections, and sepsis in particular, are characterized by extensive release of mediators. Our laboratories have been interested in understanding how these substances contribute to morbidity and mortality during various stages of surgical infections in order to develop new and more effective therapeutics and treatment strategies. In a series of in vitro studies, human plasma was exposed to lipopolysaccharide (LPS), and whole blood was treated with peptidoglycan from Staphylococcus aureus. The activity of peptidoglycan also was studied in the rat, and LPS infusion was tested in dog and pig models. In a clinical study, the relation of serum LPS to multiple organ dysfunction and failure was studied in patients in the surgical intensive care unit. Exposure of plasma to LPS led to formation of bradykinin, activation of the plasma kallikrein-kinin system, and reduction of kallikrein inhibitor capacity. The coagulation, fibrinolysis, and complement cascades were activated. Peptidoglycan caused rapid release of tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 from macrophages and activation of the genes encoding pro-inflammatory and anti-inflammatory cytokines. In the rat, peptidoglycan induced cytokine release, caused liver and kidney dysfunction, and induced matrix metalloproteinase-9 (MMP-9) activity in the liver and lung. In the dog and pig, LPS caused substantial activation of plasma proteases. Clinically, a finding of LPS in the plasma was associated with multiple organ dysfunction and failure. These patients also revealed substantial activation of the plasma cascade systems, as well as systemic cytokine release. On the basis of these observations, we developed a monitoring system to recognize early signs of infection.

Interaction of High Molecular Weight Kininogen with Endothelial Cell Receptors suPAR, gC1qR and Cytokeratin 1 by Surface Plasmon Resonance (BiaCore).

The physiologic activation of the plasma kallikrein kinin system (KKS) requires the assembly of these proteins on the cell membrane. High molecular weight kininogen (HK) binds to endothelial cells through an interaction with a multiprotein receptor complex that consist of: urokinase plasminogen activator receptor (uPAR), globular C1q receptor (gC1qR) and cytokeratin 1 (CK1). The affinity of HK and cleaved HK (Hka) for endothelial cells is KD=7–52 nM but the affinity for each of the three binding proteins is unknown. We first examined the direct binding of HK and Hka to the soluble receptor form of uPAR (suPAR), gC1qR and CK1 using surface plasmon resonance (BiaCore). We linked suPAR, gC1qR and CK1 (800–1100 pg/mm2) by amine coupling to a CM-5 chip and perfused HK and Hka at a concentration ranging from 50 to 400 nM in the presence or absence of 10 μM ZnCl2. A Langmuir binding model with local fit (stoichiometry of 1:1) was used to analyse kon (association rate constant), koff (dissociation rate constant) and KD (equilibrium dissociation constant) for HK and Hka.HKHkaKDkonkoffKDkonkoffImmobilized ProteinnMM-1s-1 x104s-1 x10-4nMM-1s-1 x104s-1 x10-4gC1qR0.8±0.712.3±5.00.8±0.50.7±0.524.4±10.91.4±0.5CK115.1±1.03.6±0.35.4±0.76.3±1.95.8±0.33.6±0.9suPAR2313.5±1465.31.0±0.7164.8±22.243.6±16.621.3±11.978.5±10.6The binding of HK and Hka to the three receptors was zinc dependent. The affinity for HK and Hka was gC1qR>CK1>suPAR. The high affinity for gC1qR and CK1 was similar for HK and Hka and was due to a very slow koff. The affinity for Hka compared to HK was 2.5-fold tighter for CK1 but 50-fold tighter for suPAR. A reversed immobiization was then performed. We immobilized HK, Hka and LK (800 pg/mm2) and suPAR, gC1qR and CK1 were flowed over the chip at a concentration ranging from 50 to 700 nM. Only gC1qR bound to immobilized HK and Hka, with a KD of 6.31± 2.8 pM for HK and 2.86±1.5 pM for Hka while the other 2 receptors did not bind. Receptor integrity was shown by preincubating HK or Hka with the pure receptors and observing competition with the immobilized receptors. Among the HK/Hka receptors, complex formation was only observed between gC1qR and immobiized CK1 with or without Hka indicating that a CK1-gC1qR complex can form independently of kininogen. This study indicates that although suPAR has the weakest affinity of the three receptors it is the only one that distinguishes between HK and Hka. Only one binary complex was revealed by this technique between CK1 and gC1qR. These results lay the foundation for anlayzing the affinity of these receptors in a cellular environment.

Contribution of the N-Terminal and C-Terminal Domains of Haemaphysalin to Inhibition of Activation of Plasma Kallikrein-Kinin System

Haemaphysalin is a kallikrein-kinin system inhibitor from hard tick Haemaphysalis longicornis, and consists of two Kunitz type protease inhibitor domains. Each domain as well as haemaphysalin inhibited intrinsic coagulation by inhibiting activation of the kallikrein-kinin system without affecting the amidolytic activities of intrinsic coagulation factors, indicating that both domains were involved in the inhibition through a similar mechanism to that for haemaphysalin. Reconstitution experiments showed that the C-terminal domain contributed more predominantly to this inhibition. Direct binding assaying showed that the C-terminal domain could bind to the cell-binding region of high molecular weight kininogen (HK), suggesting that it also binds to the cell-binding region of factor XII. Judging from these findings, the C-terminal domain may more effectively inhibit the association of factor XII and HK with the cell surface by binding to cell-binding regions, and hence would predominantly contribute to the inhibition of activation of the kallikrein-kinin system.

Identification and characterization of the plasma kallikrein-kinin system inhibitor, haemaphysalin, from hard tick, Haemaphysalis longicornis

The plasma kallikrein-kinin system inhibitor, haemaphysalin, from the hard tick, Haemaphysalis longicornis, was identified. It was found that haemaphysalin inhibited activation of the plasma kallikrein-kinin system by interfering with reciprocal activation between factor XII and prekallikrein. It did not, however, inhibit amidolytic activities of factor XIIa and kallikrein. Direct binding assay indicated that factor XII/XIIa and high molecular weight kininogen (HK) are the target molecules of haemaphysalin, and that Zn2+ ions are involved in the interactions of haemaphysalin with these target molecules. This suggests that haemaphysalin interacts with target molecules by recognizing their conformational changes induced by Zn2+ ions. Furthermore, haemaphysalin interacted with the fibronectin type II domain and domain D5, the cell binding domains of factor XII and HK, respectively. This finding suggests that haemaphysalin interferes with the association of factor XII and the prekallikrein-HK complex with a biologic activating surface by binding to these cell-binding domains, leading to inhibition of the reciprocal activation between factor XII and prekallikrein.

The Plasma and Tissue Kininogen-kallikrein-kinin System: Role in the Cardiovascular System

Bradykinin and Lys-bradykinin are potent peptide mediators implicated in several physiopathological effects in mammals. They act through activation of G-protein-coupled constitutive B(2) or inducible kinin B(1) receptors linked to signaling pathways involving increased intracellular Ca(++) concentrations and/or release of mediators including arachidonic acid metabolites, NO and EDHF. In the cardiovascular system, the kallikrein-kinin system exerts a fine control of vascular smooth muscle tone and arterial blood pressure, and plays a significant cardioprotective effect. This has been lately confirmed in experimental studies employing transgenic mice overexpressing human tissue kallikrein and animals with knockout of kinin B(1) and B(2) receptor gene. Disturbances in this system are associated with arterial hypertension, myocardial ischaemia and other clinical complications. Inhibitors of kininase II (angiotensin-converting enzyme) have been prescribed successfully to patients with cardiovascular diseases, but there is still a great interest in developing drugs or pharmacological strategies that augment the activity of kininogen-kallikrein-kinin system in pathological conditions. Delivery of adenovirus vector containing the human tissue kallikrein gene (gene kallikrein therapy) has emerged as a great potential to satisfy these conditions. This review provides a summary of plasma and tissue kallikrein-kinin system, focusing on the pharmacological properties, kinin receptors and drugs reported to interfere with their actions. The modulatory effects of the kallikrein-kinin system on cardiovascular system, particularly in regulating smooth muscle tone and arterial blood pressure and in preventing myocardium ischaemia have also been explored in the review.

B14 フタトゲチマダニ唾液腺由来カリクレイン-キニン系インヒビターに関する研究

B14 フタトゲチマダニ唾液腺由来カリクレイン-キニン系インヒビターに関する研究

A Monoclonal Antibody to High-Molecular Weight Kininogen Is Therapeutic in a Rodent Model of Reactive Arthritis

We reported that high-molecular weight kininogen is proangiogenic by releasing bradykinin and that a monoclonal antibody to high-molecular weight kininogen, C11C1, blocked its binding to endothelial cells. We now test if this antibody can prevent arthritis and systemic inflammation in a Lewis rat model. We studied 32 animals for 16 days. Group I (negative control) received saline intraperitoneally. Group II (disease-treated) received peptidoglycan-polysaccharide simultaneously with C11C1. Group III (disease-untreated) received peptidoglycan-polysaccharide simultaneously with isotype-matched mouse IgG. Group IV (disease-free-treated) and group V (disease-free isotype-treated) received saline and C11C1 or mouse IgG. Analysis of joint diameter changes showed a decrease in the C11C1 disease-treated group compared to the disease-untreated group. The hind paw inflammatory score showed a decrease in the intensity and extent of inflammation between the disease-untreated and the C11C1 disease-treated group. Prekallikrein, high-molecular weight kininogen, factor XI, and factor XII were decreased in the disease-untreated group compared to the C11C1 disease-treated group. T-kininogen was increased in the disease-untreated group when compared with the C11C1 disease-treated group. Disease-free groups IV and V did not show any sign of inflammation at any time. This study shows that monoclonal antibody C11C1 attenuates plasma kallikrein-kinin system activation, local and systemic inflammation, indicating therapeutic potential in reactive arthritis.

Human Kininogen Gene Is Transactivated by the Farnesoid X Receptor

Human kininogen belongs to the plasma kallikreinkinin system. High molecular weight kininogen is the precursor for two-chain kinin-free kininogen and bradykinin. It has been shown that the two-chain kinin-free kininogen has the properties of anti-adhesion, anti-platelet aggregation, and anti-thrombosis, whereas bradykinin is a potent vasodilator and mediator of inflammation. In this study we show that the human kininogen gene is strongly up-regulated by agonists of the farnesoid X receptor (FXR), a nuclear receptor for bile acids. In primary human hepatocytes, both the endogenous FXR agonist chenodeoxycholate and synthetic FXR agonist GW4064 increased kininogen mRNA with a maximum induction of 8-10-fold. A more robust induction of kininogen expression was observed in HepG2 cells, where kininogen mRNA was increased by chenodeoxycholate or GW4064 up to 130-140-fold as shown by real time PCR. Northern blot analysis confirmed the up-regulation of kininogen expression by FXR agonists. To determine whether kininogen is a direct target of FXR, we examined the sequence of the kininogen promoter and identified a highly conserved FXR response element (inverted repeat, IR-1) in the proximity of the kininogen promoter (-66/-54). FXR/RXRalpha heterodimers specifically bind to this IR-1. A construct of a minimal promoter with the luciferase reporter containing this IR-1 was transactivated by FXR. Deletion or mutation of this IR-1 abolished FXR-mediated promoter activation, indicating that this IR-1 element is responsible for the promoter transactivation by FXR. We conclude that kininogen is a novel and direct target of FXR, and bile acids may play a role in the vasodilation and anti-coagulation processes.