Bradykinin Levels Research Articles

Novel Vasoregulatory Aspects of Hereditary Angioedema: the Role of Arginine Vasopressin, Adrenomedullin and Endothelin-1

The elevation of bradykinin (BK) level during attacks of hereditary angioedema due to C1-Inhibitor deficiency (C1-INH-HAE) is well known. We previously demonstrated that endothelin-1 (ET-1) level also increases during C1-INH-HAE attacks. Although BK and ET-1 are both potent vasoactive peptides, the vasoregulatory aspect of the pathomechanism of C1-INH-HAE has not yet been investigated. Hence we studied the levels of vasoactive peptides in controls and in C1-INH-HAE patients, as well as evaluated their changes during C1-INH-HAE attacks. The levels of arginine vasopressin (AVP), adrenomedullin (ADM) and ET-1 were measured in the plasma of 100 C1-INH-HAE patients in inter-attack periods and of 111 control subjects, using BRAHMS Kryptor technologies. In 18 of the 100 C1-INH-HAE patients, the levels of vasoactive peptides were compared in blood samples obtained during attacks, or in inter-attack periods. AVP, ADM and ET-1 levels were similar in inter-attack samples from C1-INH-HAE patients and in the samples of controls, although cardiovascular risk has an effect on the levels of vasoactive peptides in both groups. The levels of all three vasoactive peptides increased during C1-INH-HAE attacks. Moreover, the levels of ET-1 and ADM as well as their changes during attacks were significantly correlated. This study demonstrated that vascular regulation by vasoactive peptides is affected during C1-INH-HAE attacks. Our results suggest that the cooperation of several vasoactive peptides may be necessary to counterbalance the actions of excess BK, and to terminate the attacks. This may reveal a novel pathophysiological aspect of C1-INH-HAE.

Nanofiltrated C1-esterase-inhibitor in the prophylactic treatment of bradykinin-mediated angioedema.

Patients suffering from bradykinin-induced angioedema show recurrent swelling of subcutaneous and submucosal structures. Increased bradykinin levels lead to an increase in vascular permeability and edema formation. Current therapy consists of B2 bradykinin receptor antagonists, C1-esterase-inhibitor (C1-INH) concentrate, or the kallikrein inhibitor ecallantide. In most cases the treatment of acute attacks is sufficient. Prophylactic therapy is recommended only in severe cases. C1-INHc has been shown a safe and efficient option. Its effect on the quality of life has not yet been analyzed. Patients with inadequate disease control despite an "on-demand therapy" including C1-INHc and/or the B2 receptor antagonist icatibant were switched to long-term prophylaxis consisting in an individual dose of intravenous C1-INHc (Cinryze). None of the patients had been previously treated with ecallantide. Disease-specific quality-of-life questionnaires and patient records were used for evaluation. Disease control, quality of life, adverse events, and administered dosage per month were compared for 6 months on on-demand therapy and the following 6 months under prophylactic therapy. Data of seven patients with hereditary angioedema (HAE) and one patient with acquired angioedema were evaluated. Prophylactic therapy with Cinryze led to a significant and clinically relevant reduction in the overall attack frequency from 6.7 to 2.3 per month without relevant side effects. The frequency of severe attacks was reduced by 89% and quality of life significantly improved. Prophylaxis with Cinryze led to a significantly improved quality of life in our cohort of patients with high-frequency bradykinin-induced angioedema attacks that were not sufficiently treated with on-demand medication.

Specific immunotherapy with mugwort pollen allergoid reduce bradykinin release into the nasal fluid.

IntroductionA pathomechanism of allergic rhinitis is complex. A neurogenic mechanism seems to play a significant role in this phenomenon.AimThe evaluation of influence of specific immunotherapy of mugwort pollen allergic patients on the bradykinin concentration in the nasal lavage fluid.Material and methodsThe study included 22 seasonal allergic rhinitis patients. Thirty persons with monovalent allergy to mugwort pollen, confirmed with skin prick tests and allergen-specific immunoglobulin E, underwent a 3-year-long allergen immunotherapy with the mugwort extract (Allergovit, Allergopharma, Germany). The control group was composed of 9 persons with polyvalent sensitivity to pollen, who were treated with pharmacotherapy. Before the allergen-specific immunotherapy (AIT) and in subsequent years before the pollen seasons, a provocation allergen test with the mugwort extract was performed, together with collection of nasal fluids, where bradykinin concentration was determined according to Proud method.ResultsThere were similar levels of bradykinin in both groups at baseline prior to therapy (AIT group: 584.0 ±87.2 vs. controls 606.3 ±106.5 pg/ml) and changes after allergen challenge 1112.4 ±334.8 vs. 1013.3 ±305.9 pg/ml as well. The bradykinin concentration in nasal lavage fluid after mugwort challenge in 1 year was lower in the AIT group (824.1 ±184.2 pg/ml vs. 1000.4 ±411.5 pg/l; p < 005) with a further significant decrease after the 2nd and 3rd year of specific immunotherapy. Significant reduction of symptoms and medications use was observed in hyposensitized patients.ConclusionsA decreased level of bradykinin as a result of AIT suggests that some of the symptomatic benefits of AIT may be related to the reduced release of bradykinin into nasal secretions. These values correlate with clinical improvement within the course of treatment.

The Use of Plasma-Derived Complement C1-Esterase Inhibitor Concentrate (Berinert®) in the Treatment of Angiotensin Converting Enzyme-Inhibitor Related Angioedema.

Angioedema of the upper airways is a severe and potentially life-threatening condition. The incidence has been increasing in the past two decades, primarily due to pharmaceuticals influencing the generation or degradation of the vasoactive molecule bradykinin. Plasma-derived C1-esterase inhibitor concentrate is a well-established treatment option of hereditary and acquired complement C1-esterase inhibitor deficiency, which are also mediated by an increased level of bradykinin resulting in recurrent angioedema. We here present a case of severe angiotensin converting enzyme-inhibitor related angioedema (ACEi-AE) of the hypopharynx that completely resolved rapidly after the infusion of plasma-derived C1-inhibitor concentrate adding to the sparse reports in the existing literature.

Long-term antihypertensive effects of far-infrared ray irradiated from wooden board in spontaneously hypertensive rats.

BackgroundFar-infrared ray (FIR) has been widely used in promoting health and has been shown to exert beneficial effects in vascular function. The non-thermal effect of FIR has been found to play a significant role in the protective effect on some vascular-related diseases, but its protective effects and use against hypertension have not been clearly presented.MethodsIn the present study, by using a wooden board coated with FIR-irradiated materials, we evaluated the long-term antihypertensive effect on spontaneously hypertensive rats (SHRs) in the environment in contact with the FIR-irradiated wooden board. SHRs were placed on the wooden board with or without FIR radiation for 4 weeks.ResultsThe systolic blood pressure (BP) of SHRs undergoing different treatments was measured weekly using a tail-cuff method. FIR radiation significantly reduced the systolic BP of the SHRs along with a decreasing plasma level of angiotensin II and an increasing plasma level of bradykinin. In addition, long-term contact of FIR did not significantly affect the BP in normotensive Wistar Kyoto rats (WKYs).ConclusionsOur results provided the evidence based on which FIR radiation could be considered an effective non-pharmacological choice for preventing hypertension.

Ca(2+) signals mediated by bradykinin type 2 receptors in normal pancreatic stellate cells can be inhibited by specific Ca(2+) channel blockade.

Key points Bradykinin may play a role in the autodigestive disease acute pancreatitis, but little is known about its pancreatic actions.In this study, we have investigated bradykinin‐elicited Ca2+ signal generation in normal mouse pancreatic lobules.We found complete separation of Ca2+ signalling between pancreatic acinar (PACs) and stellate cells (PSCs). Pathophysiologically relevant bradykinin concentrations consistently evoked Ca2+ signals, via B2 receptors, in PSCs but never in neighbouring PACs, whereas cholecystokinin, consistently evoking Ca2+ signals in PACs, never elicited Ca2+ signals in PSCs.The bradykinin‐elicited Ca2+ signals were due to initial Ca2+ release from inositol trisphosphate‐sensitive stores followed by Ca2+ entry through Ca2+ release‐activated channels (CRACs). The Ca2+ entry phase was effectively inhibited by a CRAC blocker.B2 receptor blockade reduced the extent of PAC necrosis evoked by pancreatitis‐promoting agents and we therefore conclude that bradykinin plays a role in acute pancreatitis via specific actions on PSCs. Normal pancreatic stellate cells (PSCs) are regarded as quiescent, only to become activated in chronic pancreatitis and pancreatic cancer. However, we now report that these cells in their normal microenvironment are far from quiescent, but are capable of generating substantial Ca2+ signals. We have compared Ca2+ signalling in PSCs and their better studied neighbouring acinar cells (PACs) and found complete separation of Ca2+ signalling in even closely neighbouring PACs and PSCs. Bradykinin (BK), at concentrations corresponding to the slightly elevated plasma BK levels that have been shown to occur in the auto‐digestive disease acute pancreatitis in vivo, consistently elicited substantial Ca2+ signals in PSCs, but never in neighbouring PACs, whereas the physiological PAC stimulant cholecystokinin failed to evoke Ca2+ signals in PSCs. The BK‐induced Ca2+ signals were mediated by B2 receptors and B2 receptor blockade protected against PAC necrosis evoked by agents causing acute pancreatitis. The initial Ca2+ rise in PSCs was due to inositol trisphosphate receptor‐mediated release from internal stores, whereas the sustained phase depended on external Ca2+ entry through Ca2+ release‐activated Ca2+ (CRAC) channels. CRAC channel inhibitors, which have been shown to protect PACs against damage caused by agents inducing pancreatitis, therefore also inhibit Ca2+ signal generation in PSCs and this may be helpful in treating acute pancreatitis.

Angiotensin converting enzyme inhibition increases ADMA concentration in patients on maintenance hemodialysis--a randomized cross-over study.

BackgroundEndothelial dysfunction occurs in patients with end-stage renal disease (ESRD) and is associated with increased cardiovascular morbidity and mortality. Asymmetric dimethylarginine (ADMA) contributes to endothelial dysfunction in ESRD. In the general population, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) decrease ADMA levels, but no study has compared the effect of these drugs in patients with ESRD on maintenance hemodialysis (MHD).MethodsWe evaluated the effect of 1-week treatment with ramipril (5 mg/d), valsartan (160 mg/d), and placebo on ADMA levels in 15 patients on MHD in a double-blind, placebo-controlled, three x three cross-over study.ResultsWe found that ADMA levels were increased at baseline and throughout the dialysis session during ramipril treatment (p < 0.001 compared to both, placebo and valsartan). Ramipril did not increase ADMA levels in a study of patients without ESRD, suggesting that factors related to ESRD or hemodialysis contribute to the ACE inhibitor-induced increase in ADMA. We have previously shown that ACE inhibition increases bradykinin (BK) levels during hemodialysis. We therefore evaluated the effect of bradykinin on ADMA production in A549 cells; a cell line that expresses BK receptors. Incubation with BK increased intracellular ADMA concentration through BK B2-receptor stimulation.ConclusionThese data indicate that short-term ACE inhibition increases ADMA in patients on MHD whereas ARBs do not. In vitro studies further suggest that this may occur through BK-mediated increase in ADMA production during ACE inhibition.Trial registrationClinicaltrials.gov NCT00732069 August 6 2008 and NCT00607672 February 4 2008Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-015-0162-x) contains supplementary material, which is available to authorized users.

Incidence of hypotension and acute hypotensive transfusion reactions following platelet concentrate transfusions.

Platelet concentrates (PCs) are associated with transfusion reactions involving hypotension, particularly bradykinin-mediated acute hypotensive transfusion reactions. This study aims to determine the incidence of hypotensive events and more specifically acute hypotensive transfusion reaction associated with PC transfusions. We also sought to ascertain whether these reactions are associated with elevated bradykinin levels. This is a prospective descriptive study of PCs administered at Sainte-Justine Hospital over 28 months. All PCs administered during this period were screened for hypotension through review of all transfusion-associated reaction reports (TARRs) sent to the blood bank. All residual PC bags were returned to the blood bank. TARRs associated with hypotension were reviewed by adjudicators that established the imputability of the PC transfusion to the reaction. Bradykinin levels were sampled in the first 168 PC bags returned to the blood bank. Levels were compared between PCs associated with hypotension and control PCs not associated with hypotension. A total of 3672 PC bags were returned to the blood bank; 25 PCs were associated with hypotension. Adjudicators ascertained that five hypotensive events were imputable to PCs of which one was an acute hypotensive transfusion reaction (incidence: 0·03%). Bradykinin level in the latter PC was 10 pg/ml, whereas levels were 226·2 ± 1252 pg/ml in the 143 control PCs. Our results show a low incidence of hypotension after PC transfusion. We identified only one acute hypotensive transfusion reaction. No correlation between bradykinin level and the occurrence of acute hypotensive reactions could be observed given that only one event was identified.

Chemotherapy Related Angioedema.

Chemotherapy Related Angioedema.

Role of plasma high-molecular-weight-kininogen in the pathogenesis of inflammatory bowel disease (MUC5P.748)

Abstract High-molecular-weight kininogen (HK) is a major component of plasma kallikrein-kinin system (KKS), its cleavage products bradykinin and HKa are proinflammatory. Clinical observations have shown that KKS activation and HK cleavage are involved in inflammatory bowel disease (IBD). However, the pathogenic role of HK in IBD have never been characterized using a genetic approach. Our goal is to characterize the role of HK in the pathogenesis of IBD，using HK-deficient (Kng1-/-) mice we recently generated. Dextran sulfate sodium (DSS)-induced colitis in mice were induced by 2.5% (wt/vol) DSS in drinking water for 7 days. Plasma bradykinin level in wild-type (WT) mice was elevated on day 7 (p&amp;lt;0.001). Weight loss index and disease activity index (DAI) of DSS-treated Kng1-/- mice were significantly lower than those of WT mice (p&amp;lt;0.05). Kng1-/- mice had a decrease in colonic cytokines (TNF-α, IL-1β, IL-6 and INF-γ) and myeloperoxidase (MPO) levels (p&amp;lt;0.001). As indicated by H&amp;E staining, Kng1-/- mice exhibited a reduced colonic tissue damage and neutrophil infiltration in colonic lamina propria (p&amp;lt;0.001). Similar with Kng1-/- mice, the mice lacking double bradykinin receptors (B1RB2R-/-) exhibited an amelioration of DSS-induced colitis, including the amelioration of weight loss, DAI, colonic tissue damage, and colonic cytokine levels. This study provides the first genetic evidence demonstrating that HK and its cleavage product bradykinin play a critical role in the pathogenesis of IBD.

Effect of Bushenwenyanghuayu decoction on nerve growth factor and bradykinin/bradykinin B1 receptor in a endometriosis dysmenorrhea mouse model

ObjectiveTo observe the effects of Bushenwenyanghuayu decoction (BD), a Traditional Chinese Medicine (TCM), on the serum concentration of nerve growth factor (NGF) and bradykinin (BK), and protein and mRNA levels of NGF and bradykinin B1 receptor (BKB1R) in a mouse model of endometriosis dysmenorrhea. MethodsSeventy-five experimental female BALB/c mice were randomly divided into five groups, 15 mice each: sham, model, BD high dose (61.67 g/kg), BD low dose (15.42 g/kg), and gestrinone (0.4 mg/kg) groups. All the mice except for those in the sham group underwent auto-transplantation surgery and were gavaged estradiol valerate (0.5 mg/kg, daily for 12 days) after surgery. On the 12th day, 1 h after administration, writhing response was induced by intraperitoneal injection of oxytocin at 2 U/mouse. The writhing frequency and latency were recorded and the volume of the ectopic foci was measured. The concentration of serum NGF and BK was detected by enzyme-linked immunosorbent assay, the protein expression of NGF and BKB1R was tested by immunohistochemistry and western blotting, and NGF and BKB1R mRNAs were detected by real-time PCR. ResultsCompared with the model group, the volume of the ectopic foci in the treatment groups was significantly lower (P < 0.01), the writhing frequency was decreased (P < 0.05), and the writhing latency was prolonged (P < 0.01). Compared with the sham group, serum NGF and BK levels in the model group were significantly increased (P < 0.01). There were positive correlations for writhing frequency among the NGF and BK groups (P < 0.01). The serum NGF and BK levels were significantly lower in the treatment groups than the model group (P < 0.05). The protein expression of NGF, BKB1R was significantly decreased in the treatment groups compared with the model group (P < 0.01). NGF and BKB1R mRNA expression was significantly decreased in the treatment groups compared with the model group (P < 0.01). ConclusionNGF and BK/BKB1R may play an important role in the development of endometriosis-associated dysmenorrhea, and BD was found to inhibit the development of endometriosis and relieve dysmenorrhea by influencing NGF and BK/BKB1R mRNA and protein levels.

Treatment of angiotensin receptor blocker-induced angioedema: A case series.

Angiotensin II receptor antagonists have been proposed as a replacement therapy after the occurrence of either an angiotensin converting enzyme (ACE) inhibitor-induced angioedema or cough. However, recent studies indicate that angioedema is associated with elevated bradykinin levels in a small fraction of patients treated with angiotensin-II-receptor blockers, suggesting a common pathophysiological mechanism. To date, a standard treatment for angiotensin II receptor blocker-induced angioedema does not exist. We present a case series of patients admitted to our hospital due to angioedema induced by an angiotensin II receptor blocker. The patients were either treated with either icatibant (n = 3) or prednisolone-21-hydrogen succinate/clemastine (n = 5). Both patient groups were compared with an untreated patient cohort (n = 3). All patients were previously diagnosed with essential hypertonia. Icatibant was an effective therapy for angiotensin II receptor blocker-induced angioedema. Full symptom recovery was achieved after 5 to 7 hours, whereas symptom remission occurred within 27 to 52 and 24 to 54 hours in patients treated with Solu-Decortin prednisolone/clemastine and untreated patients, respectively. The recovery time for icatibant was similar to that described in previous studies regarding the therapeutic efficacy of icatibant for the treatment of hereditary angioedema and patients suffering from angiotensin converting enzyme inhibitor-induced angioedema. Icatibant is a safe and effective substance for the treatment of angiotensin II receptor blocker-induced angioedema. Although the pathophysiology of angiotensin II receptor blocker-induced angioedema remains unclear, it appears to be associated with the bradykinin pathway.

Hemodynamics and vasoactive substance levels during renal congestion that occurs in the anhepatic phase of liver transplantation.

To explore hemodynamics and vasoactive substance levels during renal vein congestion that occurs in the anhepatic phase of liver transplantation. New Zealand rabbits received ligation of the hepatic pedicle, supra-hepatic vena cava and infra-hepatic vena cava [anhepatic phase group (APH); n = 8], the renal veins (RVL; n = 8), renal veins and hepatic pedicle [with the inferior vena cava left open) (RVHP; n = 8)], or a sham operation (SOP; n = 8). Hemodynamic parameters (systolic, diastolic, and mean arterial blood pressures) and the levels of serum bradykinin (BK) and angiotensin II (ANGII) were measured at baseline (0 min), and 10 min, 20 min, 30 min, and 45 min after the surgery. Correlation analyses were performed to evaluate the associations between hemodynamic parameters and levels of vasoactive substances. All experimental groups (APH, RVL, and RVHP) showed significant decreases in hemodynamic parameters (systolic, diastolic, and mean arterial blood pressures) compared to baseline levels, as well as compared to the SOP controls (P < 0.05 for all). In contrast, BK levels were significantly increased compared to baseline in the APH, RVL, and RVHP groups at all time points measured (P < 0.05 for all), whereas no change was observed in the SOP controls. There were no significant differences among the experimental groups for any measure at any time point. Further analyses revealed that systolic, diastolic, and mean arterial blood pressures were all negatively correlated with BK levels, and positively correlated with ANGII levels in the APH, RVL, and RVHP groups (P < 0.05 for all). In the anhepatic phase of orthotopic liver transplantation, renal vein congestion significantly impacts hemodynamic parameters, which correlate with serum BK and ANGII levels.

Role of Bradikynin in the Mechanism of Ischemic Preconditioning of the Heart. Prospects of Bradykinin Application in Cardiosurgical Praxis

Bradykinin level is increased in myocardium in response to short-term ischemia/reperfusion that is one of the evidences of its trigger role in ischemic preconditioning (IP). Pharmacological induced increase of endogenous bradykinin and kallidin-like peptide levels in myocardium enhances cardiac tolerance to impact of ischemia/reperfusion. Experiments with genetically modified mice indicate that kinins are involved in preconditioning but they are not the only trigger of IP. The B2-receptor blocking abolishes antiarrhythmic, infarct reducing effects ofpreconditioning, eliminates IP-induced cardiac tolerance to oxidative stress. Exogenous bradykinin mimics inotropic and cardioprotective effects of IP but does not mimic antiarrhythmic effect of preconditioning. The intracoronary or intravenous bradykinin infusion enhances human heart resistance to ischemia/reperfusion. Implementation of the cardioprotective effect of IP is provided by the activation of multiple signaling pathways that involve: B2-receptor, calcitonin gene-related peptide, NO-synthase, guanylyl cyclase, cGMP, protein kinase G, mitochondrial KATP channels, reactive oxygen species, kinases C, ERK andAkt. To increase of the human heart tolerance to ischemia/reperfusion is necessary to develop B2-receptor agonists devoid hypotensive and pro-inflammatory properties.

Diabetic Nephropathy Induced by Increased Ace Gene Dosage Is Associated with High Renal Levels of Angiotensin (1-7) and Bradykinin.

Population studies have shown an association between diabetic nephropathy (DN) and insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene (ACE in humans, Ace in mice). The aim was to evaluate the modulation of Ace copies number and diabetes mellitus (DM) on renal RAS and correlate it with indicators of kidney function. Increased number of copies of the Ace gene, associated with DM, induces renal dysfunction. The susceptibility to the development of DN in 3 copies of animals is associated with an imbalance in activity of RAS enzymes leading to increased synthesis of Ang II and Ang-(1–7). Increased concentration of renal Ang-(1–7) appears to potentiate the deleterious effects triggered by Ang II on kidney structure and function. Results also show increased bradykinin concentration in 3 copies diabetic group. Taken together, results indicate that the deleterious effects described in 3 copies diabetic group are, at least in part, due to a combination of factors not usually described in the literature. Thus, the data presented here show up innovative and contribute to understanding the complex mechanisms involved in the development of DN, in order to optimize the treatment of patients with this complication.

A crossover randomized comparative study of zofenopril and ramipril on cough reflex and airway inflammation in healthy volunteers.

BackgroundPersistent dry cough is a well known unwanted effect of Angiotensin-Converting Enzyme inhibitors (ACE-i). Animal studies have shown that the ACE-i zofenopril has a less tussigenic effect compared to the widely used ACE-i ramipril. The aim of this study was to compare cough sensitivity to inhaled tussigens, as well as spontaneous cough in response to the administration of zofenopril and ramipril in healthy volunteers; pharmacokinetic (PK) data of both zofenopril and ramipril, as well as their respective active forms, zofenoprilat and ramiprilat, was also collected.MethodsForty healthy volunteers were enrolled in a randomized crossover study. Patients were administered zofenopril calcium salt (test drug) coated tablets, 30 mg daily dose or ramipril (reference drug) tablets, 10 mg daily dose, for 7 consecutive days in two periods separated by a 21-day wash-out period. Cough sensitivity to capsaicin and citric acid was assessed as the concentration of each tussigenic agent causing at least 2 (C2) or 5 coughs (C5); spontaneous cough was also monitored throughout the study. PK parameters of zofenopril, ramipril and their active forms, were collected for each of the two study periods. Airway inflammation, as assessed by fractional exhaled nitric oxide (FeNO) and bradykinin (BK) levels, were measured prior to and following each treatment period.ResultsRamipril, but not zofenopril, increased (p < 0.01) cough sensitivity to both tussigenic agents as assessed by C2. With citric acid, C5 values calculated after both ramipril and zofenopril administration were significantly (p < 0.05 and p < 0.01, respectively) lower than corresponding control values. With both ACE-i drugs, spontaneous cough was infrequently reported by subjects.Zofenopril/zofenoprilat PK analysis showed higher area under the curve of plasma concentration, τ values (ng/ml x h) than ramipril/ramiprilat (zofenopril vs. ramipril, 84.25 ± 34.47 vs. 47.40 ± 21.30; and zofenoprilat vs. ramiprilat, 653.67 ± 174.91 vs. 182.26 ± 61.28).Both ACE-i drugs did not affect BK plasma levels; in contrast, ramipril, but not zofenopril, significantly increased control FeNO values (from 24 ± 9.6 parts per billion [PPB] to 33 ± 16 PPB; p < 0.01).ConclusionsZofenopril has a more favourable profile when compared to ramipril as shown by a reduced pro-inflammatory activity and less impact on the cough reflex.

Lethal migration: the bradykinin story.

Lethal migration: the bradykinin story.

Modulation of the kallikrein/kinin system by the angiotensin-converting enzyme inhibitor alleviates experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Bradykinin is the end-product of the kallikrein/kinin system, which has been recognized as an endogenous target for combating CNS inflammation. Angiotensin-converting enzyme (ACE) inhibitors influence the kallikrein/kinin system and reportedly have immunomodulatory characteristics. The objectives of this study were to determine whether bradykinin is involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of MS, and whether bradykinin control by the ACE inhibitor could be a therapeutic target in MS. The ACE inhibitor enalapril (1·0 or 0·2 mg/kg/day) was administered orally to EAE mice and the serum levels of bradykinin and cytokines in EAE mice were analysed. As a result, the administration of enalapril increased serum bradykinin levels, decreased the clinical and pathological severity of EAE and attenuated interleukin-17-positive cell invasion into the CNS. Additionally, bradykinin receptor antagonist administration reduced the favourable effects of enalapril. Our results suggest that bradykinin is involved in the pathomechanism underlying CNS inflammation in EAE, possibly through inhibiting cell migration into CNS. Control of the kallikrein/kinin system using ACE inhibitors could be a potential therapeutic strategy in MS.

Abstract 230: Angiotensin-Converting Enzyme Inhibition Increases ADMA Concentration in Patients on Hemodialysis

Endothelial dysfunction occurs commonly in patients with end-stage renal disease (ESRD) and is associated with increased cardiovascular morbidity and mortality. Asymmetric dimethylarginine (ADMA), an inhibitor of nitric oxidase synthase, is elevated in patients with chronic kidney disease and contributes to endothelial dysfunction in ESRD. In the general population, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) decrease ADMA levels, but no study has compared the effect of these drugs in patients with ESRD on hemodialysis. We therefore evaluated the effect of one-week treatment with ramipril (5 mg/d), valsartan (160 mg/d) and placebo on ADMA levels in fifteen patients on hemodialysis in a previously published double-blind, placebo-controlled, 3X3 cross-over study. We found that ADMA levels were increased at baseline and throughout the dialysis session during ramipril treatment (Figure 1, p&lt;0.001 compared to both placebo and valsartan). Ramipril did not increase ADMA levels in a study of patients without ESRD, suggesting that factors related to ESRD or hemodialysis contribute to the ACE inhibitor-induced increase in ADMA levels. We have previously shown that ACE inhibition increases bradykinin (BK) levels during hemodialysis. Therefore, we evaluated the effect of BK on ADMA production in A549 cells; incubation with BK increased intracellular ADMA concentration through bradykinin B2- receptor (B2R) stimulation (Figure 2). In conclusion, ACE inhibition increases ADMA in patients on hemodialysis. Studies in vitro suggest that this could occur through a bradykinin-mediated increase in ADMA production.

Neutrophil elastase causes tissue damage that decreases host tolerance to lung infection with burkholderia species.

Two distinct defense strategies can protect the host from infection: resistance is the ability to destroy the infectious agent, and tolerance is the ability to withstand infection by minimizing the negative impact it has on the host's health without directly affecting pathogen burden. Burkholderia pseudomallei is a Gram-negative bacterium that infects macrophages and causes melioidosis. We have recently shown that inflammasome-triggered pyroptosis and IL-18 are equally important for resistance to B. pseudomallei, whereas IL-1β is deleterious. Here we show that the detrimental role of IL-1β during infection with B. pseudomallei (and closely related B. thailandensis) is due to excessive recruitment of neutrophils to the lung and consequent tissue damage. Mice deficient in the potentially damaging enzyme neutrophil elastase were less susceptible than the wild type C57BL/6J mice to infection, although the bacterial burdens in organs and the extent of inflammation were comparable between C57BL/6J and elastase-deficient mice. In contrast, lung tissue damage and vascular leakage were drastically reduced in elastase-deficient mice compared to controls. Bradykinin levels were higher in C57BL/6 than in elastase-deficient mice; administration of a bradykinin antagonist protected mice from infection, suggesting that increased vascular permeability mediated by bradykinin is one of the mechanisms through which elastase decreases host tolerance to melioidosis. Collectively, these results demonstrate that absence of neutrophil elastase increases host tolerance, rather than resistance, to infection by minimizing host tissue damage.