Increased sensitivity to bradykinin among African Americans

BACKGROUND

Angioedema is a potentially life-threatening side effect of angiotensin-converting enzyme (ACE) inhibitors. Although the mechanism of angioedema is not certain, bradykinin has been implicated in its pathogenesis. Compared with Caucasians, African Americans are at an increased risk of ACE inhibitor-associated angioedema, independent of ACE inhibitor dose or concurrent medications. Because urinary kallikrein levels are decreased in African Americans with hypertension, we hypothesized that endogenous bradykinin levels may be decreased in African Americans and that they therefore may be more sensitive to ACE inhibitor-induced increases in bradykinin or to exogenous bradykinin.

OBJECTIVE

To test this hypothesis, we measured the wheal response to intradermal injection of bradykinin in salt-replete hypertensive and normotensive African Americans and Caucasians.

METHODS

Two doses of bradykinin, 1 microgram and 10 micrograms, were administered on separate days in a randomized, double-blind fashion.

RESULTS

Higher bradykinin dose (analysis of variance: F = 38.33, p < 0.001), African American race (analysis of variance: F = 17.90, p < 0.001), and hypertension (analysis of variance: F = 4.37, p = 0.05) were all associated with an increased wheal response to bradykinin.

CONCLUSION

These data provide additional support for racial differences in the kallikrein-kinin system and also implicate abnormalities of the tissue kallikrein-kinin system in essential hypertension.

Efficacy and tolerability of Icatibant (Hoe 140) in patients with moderately severe chronic bronchial asthma

Bradykinin (BK) has been identified as a mediator in human bronchial asthma. The current phase II study was designed as a multicentered, double blinded, randomized, placebo-controlled, parallel-group pilot study to investigate the efficacy of the B2 BK receptor antagonist Icatibant in adult patients with chronic asthma. Patients were treated t.i.d. with 900 micrograms or 3000 micrograms of nebulized Icatibant, or placebo. Treatment was for 4 weeks, followed by a 2-week placebo run-out. Icatibant was very well tolerated, and led to a dose-dependent improvement in objective pulmonary function tests (PFTs) measured by the investigators (e.g. FEV1 and PEFR). At 3 mg t.i.d., a statistically significant difference (p < 0.001) between Icatibant and placebo of about 10% was achieved after 4 weeks of treatment for all PFTs. At 900 micrograms t.i.d., the improvement in PFTs was smaller. By contrast, no clinically relevant improvement in global symptom score (nor a reduction of rescue medication) was found when compared with placebo. The observed improvement in objective PFTs started between weeks one and two, gradually increased until the end of active treatment, and slowly decreased during the placebo run-out phase, suggesting an anti-inflammatory effect. No acute bronchodilator effect was found. In conclusion, Icatibant showed a profile expected for an anti-inflammatory asthma drug.

Role of tachykinins in bronchoconstriction induced by intravenous administration of bradykinin in guinea-pigs

To elucidate the role of tachykinins in bronchoconstriction induced by intravenous administration of bradykinin (Bk), we studied the effects of FK224, a neurokinin-1 (NK1) and neurokinin-2 (NK2) receptor antagonist, on the bronchoconstriction induced by intravenous (i.v.) administration of Bk (5-100 micrograms.kg-1) in guinea-pigs. Total pulmonary resistance -(RL) was measured using a pressure-volume sensitive body plethysmograph in anaesthetized artificially ventilated guinea-pigs pretreated with atropine (1 mg.kg-1) and propranolol (1 mg.kg-1). In the control group, i.v. administration of Bk produced a dose-dependent increase in RL. In animals pretreated with FK224, bronchoconstriction induced by higher doses of Bk (10, 50 and 100 micrograms.kg-1) was significantly reduced, whilst the bronchoconstriction caused by lower doses of Bk (5 and 7.5 micrograms.kg-1) was not. Pretreatment with a combination of FK224 and indomethacin markedly inhibited the bronchoconstriction induced by each dose of Bk compared with the groups pretreated with FK224 alone. Although pretreatment with indomethacin alone significantly reduced RL at a high dose of Bk (50 micrograms.kg-1), the reduction was significantly lower than that produced by a combination of FK224 and indomethacin. These results suggest that intravenous administration of a high dose of bradykinin causes bronchoconstriction both by cyclo-oxygenase products and by release of tachykinins.

Effects of intranasal challenge with histamine, bradykinin and prostaglandin on middle ear pressure and blood flow in cynomolgus monkeys

Previous studies documented a significant increase in middle ear pressure following intranasal challenges with ascaris antigen or histamine in sensitized cynomolgus monkeys. To confirm that effects and investigate the mechanism, 4 monkeys were intranasally challenged at separate sessions with histamine (10 mg), bradykinin (1, 10 mg) and prostaglandin D2 (PgD2, 0.5, 1.0 mg) and followed for 90 min. Before and after challenge, middle ear pressure, mucosal blood flow, heart rate, blood pressure, body temperature and the partial pressures of O2 and CO2 in the venous blood were measured. The results showed that while bradykinin challenge had no effect on these measures, PgD2 provoked increased middle ear pressure, and histamine resulted in a biphasic pattern of increasing pressures followed by decreasing pressures. The pattern of change in middle ear pressure after histamine challenge was explicable by a mechanism involving transmucosal gas exchange, while that for PgD2 was related to increased mucosal inflammation. These results document the development of positive middle ear pressures during provoked nasal inflammation and may have relevance to similar observations in the clinical setting.

Anaphylactoid reactions during hemodialysis

Taken together, with the wide-spread use of ACE-inhibitors within the dialysis population, a novel type of hypersensitivity reaction has been recognized, which may occur not only during hemodialysis but also during other forms of extracorporeal therapy. From the data available today, it seems that such reactions are triggered by negatively charged biomaterials which are capable to activate factor XII, leading among others to the generation of bradykinin. Normally this kinin is rapidly degraded by the serine proteinase kininase II. Thus, in the absence of ACE inhibitors plasma bradykinin levels increase only moderately during dialysis with AN69 membranes and clinically most patients are free of symptoms. However, once kininase II, which is identical with converting enzyme, is blocked by ACE inhibitors, plasma levels may increase more than 100-fold and patients will suffer from severe anaphylaxis. Based on our present knowledge, the consequences for clinical medicine are straightforward. It is mandatory to avoid the combination of negatively charged membranes or other biomaterials with ACE inhibitor therapy. As there are many different membranes available, this should be no unsurmountable problem in the setting of clinical hemodialysis.

Contrast media algogenic potential in peripheral arteriography. Potentiation of bradykinin-induced pain in the rat

RATIONALE AND OBJECTIVES

Contrast media (CM) with minimal algogenic (pain causing) potential in animal models of peripheral arteriography are still able to produce vascular pain in humans; the poor predictive value of preclinical evaluation led us to develop a more sensitive method based on CM potentiation of bradykinin effects in the rat.

METHODS

Behavioral pain responses and histologic alterations of the arteries were determined after intrafemoral injection of bradykinin to saline- or CM-pretreated rats. Pain reactions were compared with those elicited by single and repeated CM injections.

RESULTS

Contrast media enhanced bradykinin-induced pain was dose dependent with the following potency order: iopamidol > iopromide > ZK 139129 > ZK 119095. Vasodilation and alterations of the arterial internal layer also were seen. Iopromide produced this sensitization at doses that did not elicit evident pain reactions per se.

CONCLUSION

The method proved to be a highly sensitive preclinical discriminant of CM algogenic potential.

Effect of hypertonic NaCl-starch-solution on oedema of different pathogenesis

Small volumes of hypertonic NaCl-solutions have been proven to restore haemodynamics in hypovolemic shock patients. Topic of this study was to investigate whether bolus application of 7.5% NaCl-6.5% starch-solution (HSS) apart from its relevance in shock might be an effective therapy in oedema. Considering differential therapeutic aspects, the volume effects of 7.2 ml HSS were tested in three types of oedema: hydrostatic oedema induced by venous congestion (n = 6), oedema caused by bradykinin injection (n = 6), and proteinase-induced oedema (n = 6). The arterial, venous pressure and weight changes indicating volume shifts between intra- and extravascular space were continuously monitored in 36 isolated perfused rabbit hindlimbs. Oedema formation was induced corresponding to a weight gain of 18-20 g. Subsequently 7.2 ml HSS were injected into the extracorporeal circulation system containing 200 ml cell free, isoosmotic perfusate. Six experiments of each oedema group without HSS-application served as controls. 75-100% of oedema formation could be remobilised via bolus application of HSS within 5 min in all types of oedema. A persisting weight reduction was detectable in the hydrostatic and bradykinin oedema, whereas in the elastase oedema the initial weight loss was followed by a regain of weight up to 180% of initial oedema formation at 120 min after HSS-application. The results show that, due to the osmotic gradient induced by bolus application of HSS, the hydrostatic and bradykinin oedema can be permanently remobilised, whereas the therapeutic effect during proteinase oedema is only short-lasting due to an irreversible damage of barrier function.

Bradykinin causes airway hyperresponsiveness and enhances maximal airway narrowing. Role of microvascular leakage and airway edema

The relationship between bronchial edema and airway responsiveness was studied in cats in situ. Five cats were exsanguinated, and the bronchial arteries were perfused. We monitored pulmonary resistance (RL), and the provocative dose of acetylcholine (ACh) required to produce a 300% increase in RL (PD300) was determined. Bronchial vascular permeability was measured by quantifying extravasation of Evans blue (EB) dye. Bradykinin (BK) and ACh were administered via the bronchial arteries to increase leakage and bronchoconstriction, respectively. BK preperfusion (for 30 min) significantly increased bronchial vascular permeability to four times the control values (p < 0.05). BK preperfusion did not alter baseline RL but caused hyperresponsiveness to ACh, with log [PD300 (mole)] of -6.53 +/- 0.42 (mean +/- SD) and -6.90 +/- 0.30, before and after BK, respectively (p < 0.01). Furthermore, the maximal airway narrowing after BK was 58% higher than before BK (p < 0.01). Histologic study showed peribronchial edema after BK. The enhancement of maximal airway narrowing was significantly correlated with the degree of EB dye extravasation. These results suggest that BK causes airway hyperresponsiveness to ACh and increases maximal airway narrowing, possibly because of airway edema.

Hypotensive effects of Lys-des-Arg9-bradykinin and metabolically protected agonists of B1 receptors for kinins

B1 receptors for kinins are selectively stimulated by bradykinin (BK) or Lys-BK (kallidin) fragments without the C terminal arginine residue. The present study was performed using an established in vivo model of B1 receptor-mediated cardiovascular action. Rabbits pretreated with bacterial lipopolysaccharide (LPS) (25 micrograms/kg) and anesthetized 5 h later exhibit acute and transient hypotension in response to intra-arterial boluses of B1 receptor agonists. The naturally occurring B1 agonist Lys-des-Arg9-BK was more potent than des-Arg9-BK in the in vivo model, but the effect of either natural sequence was brief. Evidence derived from previous in vitro experiments suggests these peptides may be substrates for angiotensin I converting enzyme (ACE). In addition, Lys-des-Arg9-BK is hydrolyzed in vitro by aminopeptidase M. Therefore, we tested the hypotensive effects of Lys-des-Arg9-BK analogs selectively protected against ACE activity (Lys-[D-Phe8]des-Arg9-BK) or against both ACE and aminopeptidase M (Sar-[D-Phe8]des-Arg9-BK). Both analogs were found to elicit a biphasic response consisting of a brief hypotensive effect followed by a prolonged hypotensive state. Indomethacin prevented only the second, prolonged phase of the hypotension induced by the metabolically protected analogs. The duration of hypotensive episodes induced by Lys-des-Arg9-BK was increased in rabbits pretreated with either captopril, an ACE inhibitor, or the aminopeptidase M inhibitor amastatin, consistent with the prolonged effect of metabolically protected analogs. An infusion of the B1 agonist Sar-[D-Phe8]des-Arg9-BK (1 microgram/min) in lipopolysaccharide-pretreated rabbits led to a very important and persistent hypotensive state that was not prevented by indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

[Significance of tachyphylaxis induced by repeated bradykinin inhalation in bronchial asthma]

Bradykinin (Bk) is a potent bronchoconstrictor agent which may contribute to the pathogenesis of bronchial asthma. Recently we have shown that repeated bronchial challenge with this agonist in asthmatics produced a specific loss of responsiveness. In vitro studies suggest that this phenomenon may be due to generation of protective prostaglandins. In this study we investigated whether flurbiprofen (F) pretreatment inhibited Bk tachyphylaxis. The efficacy of F was demonstrated by the total suppression of whole blood TxB2 formation. In addition, a time-course study of the tachyphylactic response was carried out. Refractoriness in response to inhaled Bk occurred in all subjects. The mean PC20 Bk increased from 0.07 to 0.41 mg/ml with consecutive inhalation tests after placebo. Even in the presence of demonstrable cyclooxygenase inhibition, no effect of F was observed in inhibiting Bk tachyphylaxis the mean PC20 Bk still increasing from 0.10 to 0.47 mg/ml. Tachyphylaxis was still present at 6 h, but not in all subjects at 24 h. This study demonstrated that release of protective prostaglandins in the airway after Bk stimulation does not account for the loss of responsiveness following repeated exposure to Bk. At least 24 h should separate Bk inhalations to avoid tachyphylaxis. A possible mechanism of this phenomenon is discussed.

Role of the mediators in pulmonary hyperreactivity: the cocktail interaction hypothesis

Pulmonary hyperreactivity is a common feature in asthma. In the present study we investigated the possible role of different mediators in the genesis of this phenomenon. In particular the ability of prostaglandin D2 (PGD2), substance P (SP) and bradykinin (BK) to potentiate acetylcholine (ACh)-induced bronchospasm was assessed in anaesthetized and mechanically ventilated guinea-pigs. Threshold doses of PGD2, SP and BK significantly enhanced ACh-induced bronchospasm in normal guinea-pigs, even if a different trend in the onset and duration of the phenomenon was observed. Ovalbumin (OA) active sensitization modified the ability of the three compounds tested to positively interact with ACh. Beta-adrenoceptor blockade due to propranolol treatment increased the positive interaction between the three compounds and ACh. The role of PGD2, SP and BK in the genesis of pulmonary hyperreactivity is proposed and the relevance of mediator-mediator interaction during adrenergic imbalance is discussed.

Nasal provocation with bradykinin induces symptoms of rhinitis and a sore throat

Kinins are generated in nasal secretions during allergic reactions and during induced rhinovirus colds. To determine if kinins may contribute to the symptomatology of these inflammatory reactions, 8 subjects were challenged with increasing doses of bradykinin or with placebo. Levels of albumin, histamine, and N-alpha-tosyl-L-arginine methyl ester (TAME)-esterase were measured in nasal lavages, and symptom scores were noted. No symptoms or increases in mediators or protein were observed after placebo challenge. Symptom scores increased in a dose-dependent manner, however, in response to bradykinin challenge. Increased symptoms were associated with significant increases in albumin and TAME-esterase activity, but no increases in histamine were observed. Nasal conductance measurements confirmed that bradykinin induces dose-dependent unilateral obstruction in the challenged nostril. Other common symptoms were rhinorrhea and, of particular relevance to rhinovirus infections, a persistent sore throat. We conclude that bradykinin causes increased vascular permeability and rhinitis, which are independent of mast cell mediator release. Kinins may, therefore, contribute to the symptomatology of inflammatory reactions of the upper airways, including the common cold.

Bradykinin, plasma protein fraction, and hypotension

A directive from the Food and Drug Administration indicates that the use of plasma protein fraction (PPF) is contraindicated during cardiopulmonary bypass because of possible hypotension. Bradykinin has been implicated as the cause of this hypotension. Bradykinin levels were measured by radioimmunoassay in PPF and in 5% albumin and were found to be consistently elevated in the former and occasionally in the latter. The addition of PPF to pump primes resulted in significantly elevated levels of bradykinin, which rapidly cleared, indicating that extrapulmonary sites of bradykinin inactivation were efficient. The potential hypotensive effect of PPF was observed by determining the change in mean perfusion pressure in two groups of patients: one group with a 3,000 ml crystalloid prime and the other with a prime of 2,000 ml of crystalloid and 1,000 ml of PPF. There was no significant difference in the perfusion pressure between the two groups at any point, and the hypotensive effects seen in both groups were readily treated, suggesting that the directive against the use of PPF during cardiopulmonary bypass may be unnecessarily restrictive.

Reactions to rapid infusion of stable plasma protein solution during large volume plasma exchange

Five per cent heat treated stable plasma protein solution (SPPS) has been rapidly infused into 25 patients, as fluid replacement during large volume plasmapheresis. Reactions were produced in 20 patients. Subjective symptoms of flushing, nasal stuffiness, fullness and throbbing in the head, colicky abdominal pain, metallic taste or apprehension were observed in 16 patients, and 11 patients became hypotensive with an average systolic pressure of 70 mm Hg. These observations support earlier reports of hypotension due to rapid SPPS infusion, and document the occurrence of subjective symptoms which may be the harbingers of a hypotensive reaction. In view of the known presence of a bradykinin-like substance in some heat treated plasma protein solutions, hypotension during SPPS infusion should be interpreted with caution in the light of these findings.

A kinin model of mediation for food and chemical sensitivities: biobehavioral implications

The plasma peptide hormone bradykinin is hypothesized to be a major mediator of the multiple-system functional symptomatology of adverse food and other chemical reactions. It is postulated that native foods as organic chemicals could act cumulatively with other stresses to mobilize directly the kinin-forming enzyme system.