Involvement of endogenous kinins in the pathogenesis of peptidoglycan-induced arthritis in the Lewis rat

Lipoxin A4-Mediated p38 MAPK Signaling Pathway Protects Mice Against Collagen-Induced Arthritis

The aim of the article was to study the mechanism of Lipoxin A4 (LXA4)-mediated p38 MAPK pathway protecting mice against collagen-induced arthritis (CIA). The impact of LXA4 (0, 5, 10, 15 nM) on synoviocytes proliferation of CIA mice was detected using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. CIA mice were treated with LXA4, SB203580 (a p38 inhibitor), and/or anisomycin (a p38 agonist), and the arthritis severity score in each mouse was determined. The gene or protein expressions were detected with Western Blotting, ELISA, or qRT-PCR. LXA4 inhibited the synoviocytes proliferation of CIA mice with decreased levels of TNF-α, IL-6, IL-1β, and IFN-γ and reduced p-p38/total p38 expression in synoviocytes in a dose-dependent manner. LXA4 levels were decreased in synovial tissues and plasma of CIA mice, but p-p38/total p38 expression was increased in synovial tissues. LXA4 could downregulate p-p38/total p38 expression in synovial tissues of CIA mice. Both LXA4 and SB203580 reduced arthritis severity score of CIA mice with the reduction of synovial tissue hyperplasia and inflammatory cell infiltration. CIA mice treated with LXA4 and SB203580 had lower levels of TNF-α, IL-6, IL-1β, and IFN-γ, accompanying decreased MDA as well as increased SOD, CAT,and GPx. However, anisomycin could reverse the protect effects of LXA4 on CIA mice regarding the abovementioned inflammatory factors and oxidative stress indexes. LXA4 protected mice against collagen-induced arthritis via inhibiting p38 MAPK signaling pathway, which may be a potential new therapeutic target for rheumatoid arthritis.

A critical role for plasma kallikrein in the pathogenesis of autoantibody-induced arthritis

The plasma kallikrein-kinin system (KKS) consists of serine proteases, prekallikrein (pKal) and factor XII (FXII), and a cofactor, high-MW kininogen (HK). Upon activation, activated pKal and FXII cleave HK to release bradykinin. Activation of this system has been noted in patients with rheumatoid arthritis, and its pathogenic role has been characterized in animal arthritic models. In this study, we generated 2 knockout mouse strains that lacked pKal and HK and determined the role of KKS in autoantibody-induced arthritis. In a K/BxN serum transfer-induced arthritis (STIA) model, mice that lacked HK, pKal, or bradykinin receptors displayed protective phenotypes in joint swelling, histologic changes in inflammation, and cytokine production; however, FXII-deficient mice developed normal arthritis. Inhibition of Kal ameliorated arthritis severity and incidence at early stage STIA and reduced the levels of major cytokines in joints. In addition to releasing bradykinin from HK, Kal directly activated monocytes to produce proinflammatory cytokines, up-regulated their C5aR and FcRIII expression, and released C5a. Immune complex increased pKal activity, which led to HK cleavage. The absence of HK is associated with a decrease in joint vasopermeability. Thus, we identify a critical role for Kal in autoantibody-induced arthritis with pleiotropic effects, which suggests that it is a new target for the inhibition of arthritis.-Yang, A., Zhou, J., Wang, B., Dai, J., Colman, R. W., Song, W., Wu, Y. A critical role for plasma kallikrein in the pathogenesis of autoantibody-induced arthritis.

Bradykinin Expression in Synovial Tissues and Synovial Fluids Obtained from Patients with Internal Derangement of the Temporomandibular Joint

Bradykinin has been implicated in the pathogenesis of inflammatory arthritis by virtue of the potent pro-inflammatory properties. The purpose of this study is to investigate the expression of bradykinin in patients with internal derangement of the temporomandibular joint (TMJ). We examined 33 TMJ synovial biopsy specimens from 31 patients with internal derangement of the TMJ by an immunohistochemical technique using specific antibodies. We also determined the concentration of bradykinin in 20 synovial fluids from 18 patients with TMJ internal derangement by enzyme-linked immunosorbent assay. These data were compared with those of the control subjects. Bradykinin was predominantly localized in the synovial lining cell layer of TMJ samples obtained from patients with TMJ internal derangement. Bradykinin was also detected in 19 patients' TMJ synovial fluids and the average of bradykinin concentration in the synovial fluids of patients was higher than that of the healthy controls. Although a statistically significant correlation was not observed, these findings support the hypothesis that bradykinin may also be involved in the pathogenesis of TMJ pain and synovitis.

Characterisation and mechanisms of bradykinin-evoked pain in man using iontophoresis

Bradykinin (BK) is an inflammatory mediator that can evoke oedema and vasodilatation, and is a potent algogen signalling via the B1 and B2 G-protein coupled receptors. In naïve skin, BK is effective via constitutively expressed B2 receptors (B2R), while B1 receptors (B1R) are purported to be upregulated by inflammation. The aim of this investigation was to optimise BK delivery to investigate the algesic effects of BK and how these are modulated by inflammation. BK iontophoresis evoked dose- and temperature-dependent pain and neurogenic erythema, as well as thermal and mechanical hyperalgesia (P < 0.001 vs saline control). To differentiate the direct effects of BK from indirect effects mediated by histamine released from mast cells (MCs), skin was pretreated with compound 4880 to degranulate the MCs prior to BK challenge. The early phase of BK-evoked pain was reduced in degranulated skin (P < 0.001), while thermal and mechanical sensitisation, wheal, and flare were still evident. In contrast to BK, the B1R selective agonist des-Arg9-BK failed to induce pain or sensitise naïve skin. However, following skin inflammation induced by ultraviolet B irradiation, this compound produced a robust pain response. We have optimised a versatile experimental model by which BK and its analogues can be administered to human skin. We have found that there is an early phase of BK-induced pain which partly depends on the release of inflammatory mediators by MCs; however, subsequent hyperalgesia is not dependent on MC degranulation. In naïve skin, B2R signaling predominates, however, cutaneous inflammation results in enhanced B1R responses.

Metallopeptidase activities in hereditary angioedema: effect of androgen prophylaxis on plasma aminopeptidase P

BACKGROUND

Aminopeptidase P (APP) plays an important role in the catabolism of kinins in human plasma, mostly for des-Arg(9)-bradykinin. Impaired degradation of this active bradykinin metabolite was found to be associated with a decreased APP activity in hypertensive patients who experienced angioedema while being treated with angiotensin I-converting enzyme inhibitors. The pathophysiology of hereditary angioedema is presently attributed only to a quantitative/qualitative C1 inhibitor (CI-INH) defect with increased bradykinin release.

OBJECTIVES

In the context of androgen prophylaxis, increased CI-INH function cannot fully explain protection from angioedema attacks alone because of the limited reversion of the CI-INH defects. Therefore we hypothesized that androgen prophylaxis could enhance plasma APP activity.

METHODS

Patients with hereditary angioedema were investigated for plasma metallopeptidase activities responsible for kinin catabolism (APP, angiotensin I-converting enzyme, and carboxypeptidase N) and for CI-INH function in treated and untreated patients.

RESULTS

APP activity was asymmetrically distributed in untreated patients (n = 147): the mean value was significantly lower than the value in a reference healthy and unmedicated population (n = 116; P < or = .001). Prophylaxis with androgen induced a significant increase in APP activity (P < or = .001), whereas it did not affect the other metallopeptidase activities. In both patient groups, APP activity showed a significant inverse relationship to disease severity (P < or = .001).

CONCLUSION

In addition to the effect on circulating CI-INH levels, the increase in APP levels brought on by androgens could contribute to a more effective control of the kinin accumulation considered to be responsible for the symptoms of angioedema.

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(50)s of 15nM and 20 microg/ml, respectively. C1-inhibitor and N-acetylglucosamine glycan inhibited LPS binding to HK with IC(50)s of about 10 microg/ml and 10mM, 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.

A variant in XPNPEP2 is associated with angioedema induced by angiotensin I-converting enzyme inhibitors

Angiotensin I-converting enzyme inhibitors (ACEi), which are used to treat common cardiovascular diseases, are associated with a potentially life-threatening adverse reaction known as angioedema (AE-ACEi). We have previously documented a significant association between AE-ACEi and low plasma aminopeptidase P (APP) activity. With eight large pedigrees, we hereby demonstrate that this quantitative trait is partially regulated by genetic factors. We tested APP activity using a variance-component QTL analysis of a 10-cM genomewide microsatellite scan enriched with seven markers over two candidate regions. We found significant linkage (LOD = 3.75) to a locus that includes the XPNPEP2 candidate gene encoding membrane-bound APP. Mutation screening of this QTL identified a large coding deletion segregating in one pedigree and an upstream single-nucleotide polymorphism (C-2399A SNP), which segregates in the remaining seven pedigrees. Measured genotype analysis strongly suggests that the linkage signal for APP activity at this locus is accounted for predominantly by the SNP association. In a separate case-control study (20 cases and 60 controls), we found significant association of this SNP to ACEi-induced AE (P=.0364). In conclusion, our findings provide supporting evidence that the C-2399A variant in XPNPEP2 is associated with reduced APP activity and a higher incidence of AE-ACEi.

The role of plasma high molecular weight kininogen in experimental intestinal and systemic inflammation

Inflammation is accompanied by activation of the plasma kallikrein-kinin system (KKS). KKS activation has been demonstrated in a variety of inflammatory human diseases. To further explore the participation of KKS in arthritis and inflammatory bowel disease, we used two experimental animal models in arthritis and enterocolitis. We found that activation of KKS is associated with arthritis induced by intraperitoneal injection of peptidoglycan-polysaccharide polymers (PG-PS) as well as the enterocolitis and systemic inflammation induced also by PG-PS when injected into the intestinal wall of genetically susceptible Lewis rats. We postulated that KKS participates in the pathogenesis of inflammatory reactions involved in cellular injury, coagulation, fibrinolysis, kinin formation, complement activation, cytokine secretion, and release of proteases. We demonstrated that therapy with a specific plasma kallikrein inhibitor modulated the experimental enterocolitis, arthritis, and systemic inflammation. The fact that deficiency of plasma high molecular weight kininogen in the genetically susceptible Lewis rat results in decreased chronic enterocolitis and systemic inflammation also supports our hypothesis. We suggest that KKS plays a similar role in idiopathic human intestinal inflammatory disease and arthritis, making kallikrein-kinin system proteins appealing targets for drug therapy in chronic inflammatory diseases such as rheumatoid arthritis and Crohn's disease.

The role of plasma high molecular weight kininogen in experimental intestinal and systemic inflammation

Inflammation is accompanied by activation of the plasma kallikrein-kinin system (KKS). KKS activation has been demonstrated in a variety of inflammatory human diseases. To further explore the participation of KKS in arthritis and inflammatory bowel disease, we used two experimental animal models in arthritis and enterocolitis. We found that activation of KKS is associated with arthritis induced by intraperitoneal injection of peptidoglycan-polysaccharide polymers (PG-PS) as well as the enterocolitis and systemic inflammation induced also by PG-PS when injected into the intestinal wall of genetically susceptible Lewis rats. We postulated that KKS participates in the pathogenesis of inflammatory reactions involved in cellular injury, coagulation, fibrinolysis, kinin formation, complement activation, cytokine secretion, and release of proteases. We demonstrated that therapy with a specific plasma kallikrein inhibitor modulated the experimental enterocolitis, arthritis, and systemic inflammation. The fact that deficiency of plasma high molecular weight kininogen in the genetically susceptible Lewis rat results in decreased chronic enterocolitis and systemic inflammation also supports our hypothesis. We suggest that KKS plays a similar role in idiopathic human intestinal inflammatory disease and arthritis, making kallikrein-kinin system proteins appealing targets for drug therapy in chronic inflammatory diseases such as rheumatoid arthritis and Crohn's disease.

Acute adverse reactions associated with angiotensin-converting enzyme inhibitors: genetic factors and therapeutic implications

Angiotensin-converting enzyme inhibitors (ACEIs) have been used in the treatment of various cardiovascular diseases. Despite the therapeutic benefits of ACEIs, there are several reported side effects, including chronic cough, angioedema and anaphylactoid reactions. These adverse events cannot be explained by the vasodilatory effects of this group of medications. Preliminary studies have shown that patients with a history of developing these side effects have a lower activity of an enzyme called aminopeptidase-P. This enzyme has an important role in degrading bradykinin. This defect in enzymatic activity can be partially explained by genetic variation. Using genome-wide screening strategies, the locus (loci), gene(s) and untimely polymorphisms that explain the low enzymatic activity and side effects can be identified.

Increased Kinin Levels and Decreased Responsiveness to Kinins During Aging

Kinins are vasoactive peptides released from precursors called kininogens, and serum levels of both T- and K-kininogens increase dramatically as rats age. Kinin release is tightly regulated, and here we show that serum kinin levels also increase with age, from 63 +/- 16 nmol/L in young Fisher 344 rats to 398 +/- 102 nmol/L in old animals. Both K- and T-kininogens contribute sequentially to this increase, with the increase in middle-aged animals being driven primarily by K-kininogen, whereas the further augmentation in older rats occurs by increasing T-kininogen. By measuring ERK activation, we show that aorta endothelial cells from old animals are hyporesponsive to exogenous bradykinin. However, if serum kinin levels are experimentally decreased by lipopolysaccharide treatment, then the endothelial response to bradykinin is re-established. These results indicate that serum levels of kinins increase with age, whereas the responsiveness of target cells to kinins is reduced in these same animals.

Expression and distribution of kinin B1 receptor in the rat brain and alterations induced by diabetes in the model of streptozotocin

A role for kinin B1 receptors was suggested in the spinal cord and peripheral organs of streptozotocin (STZ)-diabetic rats. The present study aims at determining whether B1 receptors are also induced and over-expressed in the brain of STZ-rats at 2, 7, and 21 days post-treatment. This was addressed by in situ hybridization using the [35S]-UTPalphaS-labeled riboprobe and by in vitro autoradiography with the radioligand [125I]-HPP-des-Arg10-Hoe 140. In control rats, B1 receptor mRNA was found widely distributed in many brain regions. Low mRNA levels were found in thalamus and hypothalamus (7-12 nCi/g) while high mRNA signals were detected in cortical regions and hippocampus (18-29 nCi/g). In diabetic rats, B1 receptor mRNA was markedly increased in hippocampus, temporal/parietal cortices and amygdala at 2 and 7 days (+88 to +150%). Low densities of B1 receptor binding sites were detected in all analyzed regions in control rats (0.18-0.37 fmol/mg tissue). In diabetic rats, B1 receptor binding sites were significantly increased in hippocampus, amygdala, temporal/parietal, and perhinal/piriform cortices (+ 55 to + 165 %) at 7 days only. Results highlight an early but transient and reversible up-regulation of B1 receptors in specific brain regions of STZ-diabetic rats. This may offer the advantage of reducing putative central side effects with B1 receptor antagonists if used for the treatment of diabetic complications in the periphery.

A monoclonal antibody against kininogen reduces inflammation in the HLA-B27 transgenic rat

The human leukocyte antigen B27 (HLA-B27) transgenic rat is a model of human inflammatory bowel disease, rheumatoid arthritis and psoriasis. Studies of chronic inflammation in other rat models have demonstrated activation of the kallikrein–kinin system as well as modulation by a plasma kallikrein inhibitor initiated before the onset of clinicopathologic changes or a deficiency in high-molecular-mass kininogen. Here we study the effects of monoclonal antibody C11C1, an antibody against high-molecular-mass kininogen that inhibits the binding of high-molecular-mass kininogen to leukocytes and endothelial cells in the HLA-B27 rat, which was administered after the onset of the inflammatory changes. Thrice-weekly intraperitoneal injections of monoclonal antibody C11C1 or isotype IgG₁ were given to male 23-week-old rats for 16 days. Stool character as a measure of intestinal inflammation, and the rear limbs for clinical signs of arthritis (tarsal joint swelling and erythema) were scored daily. The animals were killed and the histology sections were assigned a numerical score for colonic inflammation, synovitis, and cartilage damage. Administration of monoclonal C11C1 rapidly decreased the clinical scores of pre-existing inflammatory bowel disease (P < 0.005) and arthritis (P < 0.001). Histological analyses confirmed significant reductions in colonic lesions (P = 0.004) and synovitis (P = 0.009). Decreased concentrations of plasma prekallikrein and high-molecular-mass kininogen were found, providing evidence of activation of the kallikrein–kinin system. The levels of these biomarkers were reversed by monoclonal antibody C11C1, which may have therapeutic potential in human inflammatory bowel disease and arthritis.

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.

Cannabidiol-transdermal delivery and anti-inflammatory effect in a murine model

Cannabidiol (CBD) is a new drug candidate for treatment of rheumatic diseases. However, its oral administration is associated with a number of drawbacks. The objective of this study was to design a transdermal delivery system for CBD by using ethosomal carriers. CBD ethosomes were characterized by transmission electron microscopy, confocal laser scanning microscopy and differential scanning calorimetry. Results indicated that CBD and phosphatidylcholine form an eutectic mixture. In vivo application of ethosomal CBD to CDI nude mice produced a significant accumulation of the drug in the skin and in the underlying muscle. Upon transdermal application of the ethosomal system to the abdomen of ICR mice for 72 h, steady-state levels were reached at about 24 h and lasted at least until the end of the experiment, at 72 h. Furthermore, transdermal application of ethosomal CBD prevented the inflammation and edema induced by sub-plantar injection of carrageenan in the same animal model. In conclusion, ethosomes enable CBD's skin permeation and its accumulation in a depot at levels that demonstrate the potential of transdermal CBD to be used as an anti-inflammatory treatment.

Interactions between bradykinin (BK) and cell adhesion molecule (CAM) expression in peptidoglycan‐polysaccharide (PG‐PS)‐induced arthritis

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.

Bradykinin antagonists reduce leukocyte-endothelium interactions after global cerebral ischemia

The aim of the present study was to evaluate the influence of bradykinin on microcirculatory changes and outcome after global cerebral ischemia (15 minute) in Mongolian gerbils. The cerebral microcirculation was investigated by fluorescent intravital microscopy. Survival and functional outcome was evaluated up to 4 d after ischemia. Animals were treated with the selective B(1) and B(2) receptor antagonists B 9858 and CP 0597, respectively, and the nonselective B(1)/B(2) receptor antagonist B 9430. Leukocyte activation was significantly reduced by all antagonists as indicated by a significant decrease in the number of rolling (33 +/- 20, 6 +/- 8, 9 +/- 10, and 13 +/- 10) and adherent leukocytes (9 +/- 7, 3 +/- 4, 1 +/- 1, and 2 +/- 3. 100 microm(-1) x min(-1) in controls and in animals treated with B(1), B(2), and B(1)/B(2) antagonist, respectively). Arteriolar diameters were significantly reduced during reperfusion (35 +/- 11 before and 27 +/- 8 microm 40 minutes after ischemia) in animals treated with the B(2) antagonist. The postischemic hypoperfusion, however, was not affected. Mortality was significantly higher in animals treated with the B(1) and the B(1)/B(2) antagonist. The authors concluded that bradykinin is involved in postischemic disturbances of cerebral microcirculation. The therapeutic effect of specific bradykinin receptor antagonists on functional outcome, however, remains unclear.

Chronic intestinal inflammation and angiogenesis in genetically susceptible rats is modulated by kininogen deficiency

Genetically susceptible Lewis rats injected in the intestinal wall with peptidoglycan-polysaccharide (PG-APS) polymers develop chronic granulomatous enterocolitis associated with activation of the kallikrein-kinin system. To elucidate the role of high-molecular-weight kininogen (HK), we backcrossed Brown Norway rats having an HK deficiency with Lewis rats for five generations. Two new strains were produced, wild-type F5 (F5WT) and HK deficient (F5HKd), each with a approximately 97% Lewis genome. The HK values of F5WT rat plasma and F5HKd rat plasma were 0.62 +/- 0.20 and 0.08 +/- 0.03 U/ml, respectively. Among the inflammatory changes, the mean gross gut, total intestinal histologic and liver granuloma score and the white blood count were significantly lower in the F5HKd than the F5WT rats. Plasma T-kininogen was significantly less in F5HKd. Angiogenesis (mean vascular density) in the cecum was decreased significantly in F5HKd compared to F5WT. These results indicate the importance of the kallikrein-kinin system in this model of chronic enterocolitis and systemic inflammation.

Angiotensin-converting enzyme inhibitor-associated angioedema is characterized by a slower degradation of des-arginine(9)-bradykinin

Angioedema (AE) is a rare but potentially life-threatening side effect of therapy with inhibitors of angiotensin-converting enzyme (ACE), the main bradykinin (BK)- inactivating metallopeptidase in humans. The pathogenesis of ACE inhibitor (ACEi)- associated AE (AE+) is presently unknown, although there is increasing evidence of a kinin role. We analyzed the metabolism of endogenous BK (B(2) receptor agonist) and its active metabolite, des-Arg(9)-BK (B(1) receptor agonist), in the presence of an ACEi during in vitro contact activation of plasma from hypertensive patients (n = 39) who presented AE+. Kinetic parameters were compared with those measured in a control group (AE-) of hypertensive patients (n = 39) who never manifested any acute or chronic side effects while treated with an ACEi. The different kinetic parameters were analyzed using a mathematical model (y = k t(alpha) e(-beta t)) previously applied to a normal, healthy population. The slope of BK degradation, but not its formation from high-molecular-weight kininogen, was lower in AE+ patients when compared with the AE- controls. des-Arg(9)-BK accumulation during the kinetic measurements was significantly higher in AE+ plasma. This accumulation of the B(1) agonist in AE+ patients paralleled its half-life of degradation. In conclusion, our results show, for the first time, that an abnormality of endogenous des-Arg(9)-BK degradation exists in the plasma of patients with ACEi-associated AE, suggesting that its pathogenetic mechanism lies in the catabolic site of kinin metabolism.

Kininogen deficiency modulates chronic intestinal inflammation in genetically susceptible rats

Genetically susceptible Lewis rats injected in the intestinal wall with peptidoglycan-polysaccharide (PG-APS) polymers develop chronic granulomatous enterocolitis concomitant with activation of the kallikrein-kinin system. To elucidate the role of high-molecular-weight kininogen (HK) in chronic enterocolitis, we back crossed Brown-Norway rats having a HK deficiency with Lewis rats for five generations. Two new strains were produced, wild-type F5 (F5WT) and HK deficient (F5HKd), each with a approximately 97% Lewis genome. The HK values of F5WT and F5HKd rat plasma were 0.62 +/- 0.20 and 0.08 +/- 0.03 U/ml, respectively. In PG-APS-injected rats, chronic inflammation was measured by using gross gut score, histological inflammation, liver granuloma, and white blood cell count. The mean gross gut scores were significantly lower in the F5HKd than in the F5WT rats. Plasma T-kininogen was significantly less in F5HKd. These results indicate the importance of the kallikrein-kinin system in this model of chronic enterocolitis and systemic inflammation.

Effects of captopril and omapatrilat on early post-myocardial infarction survival and cardiac hemodynamics in rats: interaction with cardiac cytokine expression

The purpose of this study was to evaluate and compare the effects of simultaneous angiotensin-converting enzyme (ACE) and neutral endopeptidase 24.11 (NEP) inhibition by the vasopeptidase inhibitor omapatrilat (10 and 40 mg x kg(-1) x day(-1)) with those of the selective ACE inhibitor captopril (160 mg x kg(-1) x day(-1)) on survival, cardiac hemodynamics, and cytokine mRNA expression in left ventricular (LV) tissues 4 days after myocardial infarction (MI) in rats. The effects of the co-administration of both B1 and B2 kinin receptor antagonists (2.5 mg x kg(-1) x day(-1) each) with and without omapatrilat were also evaluated to assess the role of bradykinin (BK) during this post-MI period. Both omapatrilat and captopril treatments improve early (4 days) post-MI survival when started 4 h post-MI. The use of kinin receptor antagonists had no significant effect on survival in untreated MI rats and omapatrilat-treated MI rats. This improvement in survival with omapatrilat and captopril is accompanied by a reduced LV end-diastolic pressure (LVEDP) and pulmonary congestion. The use of kinin receptor antagonists had little effect on cardiac hemodynamics or morphologic measurements. Acute MI significantly increased the expression of cardiac cytokines (TNF-alpha, TGF-beta1, and IL-10). Captopril significantly attenuated this activation, while omapatrilat had variable effects: sometimes increasing but generally not changing activation depending on the cytokine measured and the dose of omapatrilat used. The co-administration of both kinin receptor antagonists attenuates the increase in expression of cardiac TNF-alpha and TGF-beta1 after omapatrilat treatment. Taken together, these results would suggest that despite very marked differences in the way these drugs modified the expression of cardiac cytokines, both omapatrilat and captopril improved early (4 days) post-MI survival and cardiac function to a similar extent.

Kinin receptors in pain and inflammation

Kinins are among the most potent autacoids involved in inflammatory, vascular and pain processes. These short-lived peptides, including bradykinin, kallidin and T-kinin, are generated during tissue injury and noxious stimulation. However, emerging evidence also suggests that kinins are stored in neuronal elements of the central nervous system (CNS) where they are thought to play a role as neuromediators in various cerebral functions, particularly in the control of nociceptive information. Kinins exert their biological effects through the activation of two transmembrane G-protein-coupled receptors, denoted bradykinin B(1) and B(2). Whereas the B(2) receptor is constitutive and activated by the parent molecules, the B(1) receptor is generally underexpressed in normal tissues and is activated by kinins deprived of the C-terminal Arg (des-Arg(9)-kinins). The induction and increased expression of B(1) receptor occur following tissue injury or after treatment with bacterial endotoxins or cytokines such as interleukin-1 beta and tumor necrosis factor-alpha. This review summarizes the most recent data from various animal models which convey support for a role of B(2) receptors in the acute phase of the inflammatory and pain response, and for a role of B(1) receptors in the chronic phase of the response. The B(1) receptor may exert a strategic role in inflammatory diseases with an immune component (diabetes, asthma, rheumatoid arthritis and multiple sclerosis). New information is provided regarding the role of sensory mechanisms subserving spinal hyperalgesia and intrapleural neutrophil migration that occur upon B(1) receptor activation in streptozotocin-treated rats, a model of insulin-dependent diabetes mellitus in which the B(1) receptor seems to be rapidly overexpressed. Although it is widely accepted that the blockade of kinin receptors with specific antagonists could be of benefit in the treatment of somatic and visceral inflammation and pain, recent molecular and functional evidence suggests that the activation of B(1) receptors with an agonist may afford a novel therapeutic approach in the CNS inflammatory demyelinating disorder encountered in multiple sclerosis by reducing immune cell infiltration (T-lymphocytes) into the brain. Hence, the B(1) receptor may exert either a protective or detrimental effect depending on the inflammatory disease. This dual function of the B(1) receptor deserves to be investigated further.

Bradykinin and des-Arg(9)-bradykinin metabolic pathways and kinetics of activation of human plasma

In the serum of 116 healthy individuals, exogenous bradykinin (BK) half-life (27 +/- 10 s) was lower than that of des-Arg(9)-BK (643 +/- 436 s) and was statistically different in men compared with women. The potentiating effect of an angiotensin-converting enzyme (ACE) inhibitor was, however, more extensive for BK (9.0-fold) than for des-Arg(9)-BK (2.2- fold). The activities of ACE, aminopeptidase P (APP), and kininase I were respectively 44 +/- 12, 22 +/- 9, and 62 +/- 10 nmol x min(-1) x ml(-1). A mathematical model (y = kt(alpha)e(-beta t), t > 0), applied to the BK kinetically released from endogenous high-molecular-weight kininogen (HK) during plasma activation in the presence of an ACE inhibitor, revealed a significant difference in the rate of formation of BK between men and women. For des-Arg(9)-BK, the active metabolite of BK, the rate of degradation was higher in women compared with men, correlating significantly with serum APP activity (r(2) = 0.6485, P < 0.001). In conclusion, these results constitute a basis for future pathophysiological studies of inflammatory processes where activation of the contact system of plasma and the kinins is involved.

Effects of the vasopeptidase inhibitor omapatrilat on cardiac endogenous kinins in rats with acute myocardial infarction

The purposes of this study were to evaluate and to compare the effects of simultaneous angiotensin-converting enzyme (ACE) and neutral endopeptidase 24.11 (NEP) inhibition by the vasopeptidase inhibitor omapatrilat (1 mg. kg(-1). day(-1)) with those of the selective ACE inhibitor enalapril (1 mg. kg(-1). day(-1)) on survival, cardiac hemodynamics, and bradykinin (BK) and des-Arg(9)-BK levels in cardiac tissues 24 h after myocardial infarction (MI) in rats. The effect of the co-administration of both B(1) and B(2) kinin receptor antagonists (2.5 mg. kg(-1). day(-1) each) with metallopeptidase inhibitors was also evaluated. The pharmacological treatments were infused subcutaneously using micro-osmotic pumps for 5 days starting 4 days before the ligation of the left coronary artery. Immunoreactive kinins were quantified by highly sensitive and specific competitive enzyme immunoassays. The post-MI mortality of untreated rats with a large MI was high; 74% of rats dying prior to the hemodynamic study. Mortality in the other MI groups was not significantly different from that of the untreated MI rats. Cardiac BK levels were not significantly different in the MI vehicle-treated group compared with the sham-operated rats. Both omapatrilat and enalapril treatments of MI rats significantly increased cardiac BK concentrations compared with the sham-operated group (P < 0.05). However, cardiac BK levels were significantly increased only in the MI omapatrilat-treated rats compared with the MI vehicle-treated group (P < 0.01). Cardiac des-Arg(9)-BK concentrations were not significantly modified by MI, and MI with omapatrilat or enalapril treatment compared with the sham-operated group. The co-administration of both kinin receptor antagonists with MI omapatrilat- and enalapril-treated rats had no significant effect on cardiac BK and des-Arg(9)-BK levels. Thus, the significant increase of cardiac BK concentrations by omapatrilat could be related to a biochemical or a cardiac hemodynamic parameter on early (24 h) post-MI state.

The kallikrein-kininogen-kinin system: lessons from the quantification of endogenous kinins

The purpose of the present review is to describe the place of endogenous kinins, mainly bradykinin (BK) and des-Arg(9)-BK in the kallikrein-kininogen-kinin system, to review and compare the different analytical methods reported for the assessment of endogenous kinins, to explain the difficulties and the pitfalls for their quantifications in biologic samples and finally to see how the results obtained by these methods could complement and extend the pharmacological evidence of their pathophysiological role.

Anomaly of the des-Arg9-bradykinin metabolism associated with severe hypotensive reactions during blood transfusions: a preliminary study

BACKGROUND

Severe hypotensive reactions have been described after the transfusion of platelets or red cells through negatively-charged bedside white cell-reduction filters. The possibility of a role for bradykinin (BK) in the genesis of these reactions has been raised.

STUDY DESIGN AND METHODS

To understand if an anomaly of BK metabolism is associated with these reactions, the metabolism of BK and des-Arg9-BK was studied in the sera of four patients who presented with a severe hypotensive transfusion reaction. Tests were performed in the absence and the presence of complete in vitro inhibition of angiotensin-converting enzyme (ACE) activity by enalaprilat.

RESULTS

In the presence of ACE inhibition (enalaprilat), the half-life (t1/2) of BK measured in the sera of patients who presented with a severe hypotensive transfusion reaction (361 +/- 90 sec) was not significantly different from that measured in the sera of normal controls (249 +/- 16 sec). In the presence of ACE inhibition (enalaprilat), the t1/2 of des-Arg9-BK was significantly greater in patients who presented with a severe hypotensive transfusion reaction (1549 +/- 319 sec) than in normal controls (661 +/- 38 sec) (p < 0.001).

CONCLUSION

A metabolic anomaly mainly affecting the degradation of des-Arg9-BK could be responsible for its accumulation in vivo. Des-Arg9-BK could be responsible, at least in part, for severe hypotensive transfusion reactions.

Plasma and tissue kallikrein in arthritis and inflammatory bowel disease

To ascertain the participation of the plasma kallikrein-kinin system (KKS) in arthritis and inflammatory bowel disease, we used two rat models resembling rheumatoid arthritis and Crohn's disease. Proteoglycan-polysaccharide from group A streptococcus (PG-APS) produced chronic destructive inflammation and systemic response in the genetically susceptible Lewis rat, in the joints when injected intraperitoneally and in the bowel when injected into the gut wall. In both models, the KKS is activated, as evidenced by decreased prekallikrein, factor XI and high molecular weight kininogen. A specific plasma kallikrein inhibitor, Bz-Pro-Phe-boroarginine, reverses the plasma changes as well as the clinical gross and microscopic pathology of both the experimental arthritis and the inflammatory bowel disease in the genetically susceptible rats. We have also shown that the tissue kallikrein system is involved in the intestinal inflammatory changes. Intestinal tissue kalikrein (ITK) is localized in goblet cells in both normal and inflamed tissue. In chronic granulomatous inflammation, ITK is localized in macrophages. ITK decreases in chronic inflammation, probably due to secretion, since the mRNA is unchanged. Kallikrein binding protein, the ITK inhibitor, decreases due to enzyme-inhibitor complexes. Both plasma and tissue kallikrein are appealing targets for drug therapy of rheumatoid arthritis and Crohn's disease.

Increase in blood bradykinin concentration after eccentric weight-training exercise in men

The purpose of this study was to verify the possible appearance in the blood of bradykinin (BK) and des-Arg(9)-bradykinin (des-Arg(9)-BK) after eccentric exercise in 13 male subjects. Eccentric exercise (5 x 10 leg presses at 120% maximal voluntary concentric contraction) resulted in muscle damage and inflammation, as suggested by the significant increase in serum creatine kinase activity (from 204 +/- 41 to 322 +/- 63 U/l 12 h postexercise) and by severe lasting pain, which also peaked at 12 h postexercise. Blood BK and des-Arg(9)-BK concentrations were measured by competitive enzyme immunoassays using highly specific polyclonal rabbit IgG. Des-Arg(9)-BK concentration was not modified (preexercise: 44 +/- 14 pmol/l; pooled postexercise: 47 +/- 4 pmol/l). In contrast, BK concentration significantly increased immediately after the exercise session (68 +/- 9 vs. 42 +/- 3 pmol/l preexercise) and returned to basal values at 12, 24, and 48 h (pooled value: 40 +/- 4 pmol/l). This observation suggests that the inflammatory process due to eccentric exercise-induced muscle damage could be mediated in part by BK.

Serum metabolism of bradykinin and des-Arg9-bradykinin in patients with angiotensin-converting enzyme inhibitor-associated angioedema

Angioedema (AE) associated with angiotensin-converting enzyme inhibitors (ACEi) is a rare, but potentially life-threatening adverse reaction. Several studies have suggested that bradykinin (BK) is responsible for ACEi-induced AE, but the mechanism remains unclear. We investigated the metabolism of BK and des-Arg9-BK in the serum of 20 patients with a history of ACEi-associated AE and 21 control (C) subjects. Synthetic BK was incubated with the sera for various periods of time and residual BK and generated des-Arg9-BK were quantified by specific and sensitive enzyme immunoassays. No significant difference of half-life (t1/2) of both BK and des-Arg9-BK could be measured between C subjects and patients with AE (AE) in absence of ACEi. However, an analysis according to the prolonged (+) or not (-) t1/2 of des-Arg9-BK allowed a new stratification of C subjects and AE patients in four subgroups. The preincubation of sera with enalaprilat at a concentration inhibiting ACE significantly prevented the rapid degradation of BK and des-Arg9-BK in these four subgroups. In presence of ACEi, a subgroup (50%) of AE patients (AE + ) had a particularly significant rise of the t1/2 of des-Arg9-BK. Once ACE was inhibited, the concentration or the nature of the ACEi had no significant effect on the t1/2 of des-Arg9-BK. However, a test dilution of AE + sera with a control (C) serum showed that an enzyme defect rather than a circulating inhibitor could be responsible for the abnormal metabolism of des-Arg9-BK when ACE is inhibited. In conclusion, half of the patients with ACEi-associated AE present in serum had an enzyme defect involved in the des-Arg9-BK metabolism leading to its accumulation. The B1 agonist could be responsible, at least in part, for the local inflammatory reaction associated with the AE.

Absence of effect of chronic angiotensin II type 1 receptor blockade on endogenous kinin concentrations-induced paw edema model in the rat

The effects of chronic treatment with losartan. an AT1 receptor antagonist, on the tissue content of bradykinin (BK) and des-Arg9-BK and on their pharmacological effects were examined in the carrageenan-induced paw edema model (0.5% solution, 50 microl/paw) in the rat. These effects were compared with those of angiotensin-converting enzyme inhibitors (ACEi). For this purpose, rats were chronically treated with losartan (3, 10 and 30 mg/kg/day) and enalapril or quinapril (1 mg/kg/day). Endogenous BK and des-Arg9-BK tissue contents at the site of local inflammation were measured by highly sensitive and specific enzyme immunoassays. Losartan 3 mg/kg/day for 7, 14 and 28 days had no significant effect on carrageenan-induced paw edema, but both losartan 10 and 30 mg/kg/day for 14 days significantly increased the hindpaw volume by 50% at 3 h and by 59% at 5 h. These effects, similar to those measured for ACEi, were inhibited by icatibant, a B2 kinin receptor antagonist (32.5 nmol/paw), that reduced carrageenan-induced paw edema to the level seen in vehicle-treated rats. In the same model, and contrary to ACEi, losartan 3, 10 and 30 mg/kg/day for 14 days had no significant effect on endogenous BK and des-Arg9-BK levels in the local inflammatory site or on circulating and tissue ACE activities. These results show, at least in that model, that the potentiating effects of losartan on carrageenan-induced paw edema are independent of the concentrations of endogenous kinins.

Specific inhibition of plasma kallikrein modulates chronic granulomatous intestinal and systemic inflammation in genetically susceptible rats

The kallikrein-kinin (K-K) (contact) system is activated during acute and chronic relapsing phases of enterocolitis induced in genetically susceptible Lewis rats by intramural injection of peptidoglycan-polysaccharide (PG-APS). Using the selective plasma kallikrein inhibitor P8720, we investigate whether activation of the K-K system plays a primary role in chronic granulomatous intestinal and systemic inflammation in this model. Group I (negative control) received human serum albumin intramurally. Group II (treatment) received PG-APS intramurally and P8720 orally. Group III (positive control) received PG-APS intramurally and albumin orally. P8720 attenuated the consumption of the contact proteins, high molecular weight kininogen (P<0.03), and factor XI (P<0.04) in group II vs. group III. P8720 decreased chronic intestinal inflammation measured by blinded gross (P<0.01) and histologic (P<0.0005) scores as well as systemic complications (arthritis, splenomegaly, hepatomegaly, leukocytosis, and acute-phase reaction) (P<0.01) in group II as compared with group III. We conclude that relapsing chronic enterocolitis and systemic complications are in part due to plasma K-K system activation, and that inhibition of this pathway is a potential therapeutic approach to human inflammatory bowel disease and associated extraintestinal manifestations.

Kinin receptors

Rapid developments are expected in the molecular pharmacology of both B1, and B2 types of kinin receptors, since the underlying genetic structures are now known and widely studied. The consequences of kinin receptor duality and physiopathological regulation have not yet been fully appreciated. Medicinal chemistry is also an active front of research in kinin pharmacology, as more effective drugs targeted at kinin receptors are regularly reported. Various complementary molecular approaches (the receptor binding, cloning, immunoreacting, mutagenesis, inactivation, the study of regulation, allelic polymorphisms, and so forth) are expanding our knowledge of the role of kinins in allergy, inflammation, and singularly, renal medicine.