Contribution of bradykinin B(1) and B(2) receptors in allergen-induced bronchial hyperresponsiveness

Down-Expression of Kinin Receptors in Allergic Nasal Polyps Epithelia: An Immunohistochemistry Study

OBJECTIVES

To investigate the expression of B1 and B2 receptors in patients with nasal polyps (NPs) compared to controls.

STUDY DESIGN

Retrospective case series.

SETTINGS

Single academic center.

SUBJECTS AND METHODS

Nasal biopsies of patients with NPs were compared to inferior turbinates of control patients. Comparisons included basic demographics and comorbidities, intensity of inflammation, and immunohistochemical staining of B1 and B2 receptors measured by immunohistochemistry staining scores (ISSs).

RESULTS

A total of 41 patients were enrolled, with 21 patients (51.2%) in the NP group and 20 patients as controls. No differences were found in the prevalence of allergic comorbidities and smoking between the groups. The NP group demonstrated significantly higher prevalence of moderate and severe mononuclear infiltrates compared to the control group (57.1% vs 5.3%, P < .001). The NP group had significantly lower B1 expression in smooth muscle compared to the control group (mean ISS 0.22 vs 1.56, P < .001, respectively) and significantly more B2 expression in epithelial cells (mean ISS 1.81 vs 0, P < .001, respectively).

CONCLUSION

Patients with NPs exhibit different expression patterns of B1 and B2 compared to control patients. This implies that bradykinin receptor regulation participates in the pathogenesis of NPs.

Cigarette Smoke Particles-Induced Airway Hyperreactivity in Vivo and in Vitro

Cigarette smoke is a well-known strong risk factor for inducing airway hyperreactivity (AHR), but the underlying molecular mechanisms are not fully understood. In the present study, mouse in-vivo and in-vitro models were used to study effects of dimethyl sulfoxide (DMSO)-extracted cigarette smoke particles (DSP) on the airway, and to explore the underlying molecular mechanisms that are involved in DSP-induced AHR. In mouse in-vivo model, DSP (0.75, 1.5 or 3 µL/mL) was administered intranasally daily for 7 d. At the end of this period, lung functions were measured with flexiVent™. The results showed that the mice exhibited AHR in a dose-dependent manner following methacholine inhalation in vivo. In mouse in-vitro organ culture model, exposure of mouse tracheal segments to DSP (0.1 µL/mL) with or without the following pharmacological inhibitors: specific c-Jun-N-terminal kinase (JNK) inhibitor SP600125 (10 µM) or the anti-inflammatory drug dexamethasone (1 µM). DSP-induced bradykinin receptor-mediated airway contraction with increased mRNA and protein expressions for bradykinin B1 and B2 receptors could be significantly reduced by SP600125 or dexamethasone. In conclusion, the present study demonstrates that DSP could induce AHR in vivo and in vitro. In addition to this, the upregulation of bradykinin receptors in airway is most likely one of the underlying molecular mechanisms involved.

Bradykinin in asthma: Modulation of airway inflammation and remodelling

Bradykinin, a pro-inflammatory molecule, and its related peptides have been studied for their effects on acute reactions in upper and lower airways, where they can be synthesised and metabolized after exposure to different stimuli including allergens and viral infection. Bradykinin B₁ and B₂ receptors are constitutively expressed in the airways on several residential and/or immune cells. Their expression can also be induced by inflammatory mediators, usually associated with eosinophil and neutrophil recruitment, such as IL-4, IL-13, TNF-α, IL-6 and IL-8, via intracellular MAPK and NF-κB signalling. In turn, the latters up-regulate both bradykinin receptors. Bradykinin activates epithelial/endothelial and immune cells, neurons and mesenchymal cells (such as fibroblasts, myofibroblasts and smooth muscle cells), which are implicated in the development of airway chronic inflammation, responsiveness and remodelling (a major feature of severe asthma). This review highlights the role of bradykinin and its receptors in respect to chronic inflammatory response involving eosinophils/neutrophils and to vascular/matrix-related airway remodelling in asthmatic airways. This scenario is especially important for understanding the mechanisms involved in the pathogenesis of eosinophilic and/or neutrophilic asthma and hence their therapeutic approach.

Kinin B1 receptors as a therapeutic target for inflammation

INTRODUCTION

Kinins are peptide mediators exerting their pro-inflammatory actions by the selective stimulation of two distinct G-protein coupled receptors, termed BKB1R and BKB2R. While BKB2R is constitutively expressed in a multitude of tissues, BKB1R is hardly expressed at baseline but highly inducible by inflammatory mediators. In particular, BKB1R was shown to be involved in the pathogenesis of numerous inflammatory diseases. Areas covered: This review intends to evaluate the therapeutic potential of substances interacting with the BKB1R. To this purpose we summarize the published literature on animal studies with antagonists and knockout mice for this receptor. Expert Opinion: In most cases the pharmacological inhibition of BKB1R or its genetic deletion was beneficial for the outcome of the disease in animal models. Therefore, several companies have developed BKB1R antagonists and tested them in phase I and II clinical trials. However, none of the developed BKB1R antagonists was further developed for clinical use. We discuss possible reasons for this failure of translation of preclinical findings on BKB1R antagonists into the clinic.

Plasma contact system activation drives anaphylaxis in severe mast cell-mediated allergic reactions

BACKGROUND

Anaphylaxis is an acute, potentially lethal, multisystem syndrome resulting from the sudden release of mast cell-derived mediators into the circulation.

OBJECTIVES AND METHODS

We report here that a plasma protease cascade, the factor XII-driven contact system, critically contributes to the pathogenesis of anaphylaxis in both murine models and human subjects.

RESULTS

Deficiency in or pharmacologic inhibition of factor XII, plasma kallikrein, high-molecular-weight kininogen, or the bradykinin B2 receptor, but not the B1 receptor, largely attenuated allergen/IgE-mediated mast cell hyperresponsiveness in mice. Reconstitutions of factor XII null mice with human factor XII restored susceptibility for allergen/IgE-mediated hypotension. Activated mast cells systemically released heparin, which provided a negatively charged surface for factor XII autoactivation. Activated factor XII generates plasma kallikrein, which proteolyzes kininogen, leading to the liberation of bradykinin. We evaluated the contact system in patients with anaphylaxis. In all 10 plasma samples immunoblotting revealed activation of factor XII, plasma kallikrein, and kininogen during the acute phase of anaphylaxis but not at basal conditions or in healthy control subjects. The severity of anaphylaxis was associated with mast cell degranulation, increased plasma heparin levels, the intensity of contact system activation, and bradykinin formation.

CONCLUSIONS

In summary, the data collectively show a role of the contact system in patients with anaphylaxis and support the hypothesis that targeting bradykinin generation and signaling provides a novel and alternative treatment strategy for anaphylactic attacks.

Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

INTRODUCTION

Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments.

METHODS

Segments were cultured for 24h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry.

RESULTS

The organ culture procedure markedly increased bradykinin- (selective B₂ receptor agonist) and des-Arg⁹-bradykinin- (selective B₁ receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE₂. The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg⁹-bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B₂ receptors, but not those on B₁. Dexamethasone completely abolished kinin-induced relaxations.

CONCLUSION

It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in some patients with asthma.

MAPK/NF-κB-dependent upregulation of kinin receptors mediates airway hyperreactivity: a new perspective for the treatment

Airway hyperreactivity (AHR) is a major feature of asthmatic and inflammatory airways. Cigarette smoke exposure, and bacterial and viral infections are well-known environmental risk factors for AHR, but knowledge about the underlying molecular mechanisms on how these risk factors lead to the development of AHR is limited. Activation of intracellular mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B (NF-κB) and their related signal pathways including protein kinase C (PKC), phosphoinositide 3-kinase (PI3K) and protein kinase A (PKA) signaling pathways may result in airway kinin receptor upregulation, which is suggested to play an important role in the development of AHR. Environmental risk factors trigger the production of pro-inflammatory mediators such as tumor necrosis factor-α (TNF-α) and interleukins (ILs) that activate intracellular MAPK- and NF-κB-dependent inflammatory pathways, which subsequently lead to AHR via kinin receptor upregulation. Blockage of intracellular MAPK/NF-κB signaling prevents kinin B₁ and B₂ receptor expression in the airways, resulting in a decrease in the response to bradykinin (kinin B₂ receptor agonist) and des-Arg⁹-bradykinin (kinin B₁ receptor agonist). This suggests that MAPK- and NF-κB-dependent kinin receptor upregulation can provide a novel option for treatment of AHR in asthmatic as well as in other inflammatory airway diseases.

Intranasal administration of poly(I:C) and LPS in BALB/c mice induces airway hyperresponsiveness and inflammation via different pathways

Background

Bacterial and viral infections are known to promote airway hyperresponsiveness (AHR) in asthmatic patients. The mechanism behind this reaction is poorly understood, but pattern recognizing Toll-like receptors (TLRs) have recently been suggested to play a role.

Materials and Methods

To explore the relation between infection-induced airway inflammation and the development of AHR, poly(I:C) activating TLR3 and LPS triggering TLR4, were chosen to represent viral and bacterial induced interactions, respectively. Female BALB/c or MyD88-deficient C57BL/6 mice were treated intranasally with either poly(I:C), LPS or PBS (vehicle for the control group), once a day, during 4 consecutive days.

Results

When methacholine challenge was performed on day 5, BALB/c mice responded with an increase in airway resistance. The maximal resistance was higher in the poly(I:C) and LPS treated groups than among the controls, indicating development of AHR in response to repeated TLR activation. The proportion of lymphocytes in broncheoalveolar lavage fluid (BALF) increased after poly(I:C) treatment whereas LPS enhanced the amount of neutrophils. A similar cellular pattern was seen in lung tissue. Analysis of 21 inflammatory mediators in BALF revealed that the TLR response was receptor-specific. MyD88-deficient C57BL/6 mice responded to poly (I:C) with an influx of lymphocytes, whereas LPS caused no inflammation.

Conclusion

In vivo activation of TLR3 and TLR4 in BALB/c mice both caused AHR in conjunction with a local inflammatory reaction. The AHR appeared to be identical regardless of which TLR that was activated, whereas the inflammation exhibited a receptor specific profile in terms of both recruited cells and inflammatory mediators. The inflammatory response caused by LPS appeared to be dependent on MyD88 pathway. Altogether the presented data indicate that the development of AHR and the induction of local inflammation might be the result of two parallel events, rather than one leading to another.

Up-regulation of bradykinin B2 receptor by Pseudomonas aeruginosa via the NF-κB pathway

As the first line of host defense, inflammatory responses in response to bacterial infection are initiated by the production of a range of mediators. Infection of Pseudomonas aeruginosa has been shown to stimulate the production of bradykinin (BK), which is known as a universal mediator for the induction of inflammatory reaction via the predominant interaction with the bradykinin B2 receptor (B2R). Thus, the interaction between BK and B2R represents an important host innate response against invading P. aeruginosa. However, the contribution of P. aeruginosa to the up-regulation of B2R expression remains unclear. Here, we report that P. aeruginosa is potent in inducing the expression of B2R at the mRNA and protein levels in a dose- and time-dependent manner. Components produced and secreted from P. aeruginosa could play an essential role in inducing B2R expression, and the secreted components are not under the control of Type III secretion system or quorum sensing. B2R expression in response to P. aeruginosa is mediated by the induction of cellular signaling that leads to the activation of transcription factor NF-κB. Thus, this study demonstrates that P. aeruginosa is able to up-regulate the expression of B2R during infection via the NF-κB signaling pathway.

Bradykinin-induced lung inflammation and bronchoconstriction: role in parainfluenze-3 virus-induced inflammation and airway hyperreactivity

Inhaled bradykinin causes bronchoconstriction in asthmatic subjects but not nonasthmatics. To date, animal studies with inhaled bradykinin have been performed only in anesthetized guinea pigs and rats, where it causes bronchoconstriction through sensory nerve pathways. In the present study, airway function was recorded in conscious guinea pigs by whole-body plethysmography. Inhaled bradykinin (1 mM, 20 s) caused bronchoconstriction and influx of inflammatory cells to the lungs, but only when the enzymatic breakdown of bradykinin by angiotensin-converting enzyme and neutral endopeptidase was inhibited by captopril (1 mg/kg i.p.) and phosphoramidon (10 mM, 20-min inhalation), respectively. The bronchoconstriction and cell influx were antagonized by the B(2) kinin receptor antagonist 4-(S)-amino-5-(4-{4-[2,4-dichloro-3-(2,4-dimethyl-8-quinolyloxymethyl)phenylsulfonamido]-tetrahydro-2H-4-pyranylcarbonyl}piperazino)-5-oxopentyl](trimethyl)ammonium chloride hydrochloride (MEN16132) when given by inhalation (1 and 10 μM, 20 min) and are therefore mediated via B(2) kinin receptors. However, neither intraperitioneal MEN16132 nor the peptide B(2) antagonist icatibant, by inhalation, antagonized these bradykinin responses. Sensitization of guinea pigs with ovalbumin was not sufficient to induce airway hyperreactivity (AHR) to the bronchoconstriction by inhaled bradykinin. However, ovalbumin challenge of sensitized guinea pigs caused AHR to bradykinin and histamine. Infection of guinea pigs by nasal instillation of parainfluenza-3 virus produced AHR to inhaled histamine and lung influx of inflammatory cells. These responses were attenuated by the bradykinin B(2) receptor antagonist MEN16132 and H-(4-chloro)DPhe-2'(1-naphthylalanine)-(3-aminopropyl)guanidine (VA999024), an inhibitor of tissue kallikrein, the enzyme responsible for lung synthesis of bradykinin. These results suggest that bradykinin is involved in virus-induced inflammatory cell influx and AHR.

Transcriptional activity of genes-encoding kinin B1 and B2 receptors and kinin-dependent genes in nasal polyps

PURPOSE

The pro-inflammatory effects of kinins are mediated by two bradykinin receptors: BR1 and BR2. The aim of this study was to evaluate the expression profile of kinin receptor genes by an estimation of mRNA levels in human nasal polyps (NP) and normal mucosa (NM).

MATERIAL AND METHODS

BR1 and BR2-dependent genes differentially transcribed in NP were investigated using oligonucleotide microarray technology. The mRNA copy number of BR1, BR2 and TIMP1 genes was assessed by QRT-PCR. Thirty six eosinophilic (ENP), 17 neutrophilic nasal polyps (NNP) and 28 NM samples were included into the study.

RESULTS

Among 92 genes encoding proteins involved in signal transduction via B1 and B2 kinin receptors TIMP1 was found to be 2,63-fold higher in the NP than in NM. Increased TIMP1 gene expression was proved by QRT-PCR (p=0,003). Moreover two genes: FOS and PTGS1 presented higher (3,82- and 4,27-fold, respectively) expression in NM compared to NP tissues. In QRT-PCR analysis insignificantly higher expression of gene encoding BR1 in ENP [2564 mRNA copies/microg RNA (22-32863)] compared with NM [1426 copies mRNA (15-27995)] was found. mRNA expression for the BR2 in ENP [9872 copies mRNA (19-244832)] was insignificantly higher than in NM [5753 copies (46-199658)]. BR2 mRNA was the predominant transcript in most NP and NM samples followed by BR1 mRNA (p<0,01). There was a positive correlation between the expression of BR1 and BR2 in the ENP (r=0,91; p<0,01) and NNP (r=0,6; p<0,01).

CONCLUSIONS

We did not document any changes in the expression profile of kinin receptors in the analyzed groups, which may suggest that kinin receptors do not make an important contribution in the etiology of NP.

Nicotine enhances murine airway contractile responses to kinin receptor agonists via activation of JNK- and PDE4-related intracellular pathways

Background

Nicotine plays an important role in cigarette-smoke-associated airway disease. The present study was designed to examine if nicotine could induce airway hyperresponsiveness through kinin receptors, and if so, explore the underlying mechanisms involved.

Methods

Murine tracheal segments were cultured for 1, 2 or 4 days in serum-free DMEM medium in presence of nicotine (1 and 10 μM) or vehicle (DMSO). Contractile responses induced by kinin B₁ receptor agonist, des-Arg⁹-bradykinin, and B₂ receptor agonist, bradykinin, were monitored with myographs. The B₁ and B₂ receptor mRNA expressions were semi-quantified using real-time PCR and their corresponding protein expressions assessed with confocal-microscopy-based immunohistochemistry. Various pharmacological inhibitors were used for studying intracellular signaling pathways.

Results

Four days of organ culture with nicotine concentration-dependently increased kinin B₁ and B₂ receptor-mediated airway contractions, without altering the kinin receptor-mediated relaxations. No such increase was seen at day 1 or day 2. The airway contractile responses to 5-HT, acetylcholine and endothelin receptor agonists remained unaffected by nicotine. Two different neuronal nicotinic receptor antagonists MG624 and hexamethonium blocked the nicotine-induced effects. The enhanced contractile responses were accompanied by increased mRNA and protein expression for both kinin receptors, suggesting the involvement of transcriptional mechanisms. Confocal-microscopy-based immunohistochemistry showed that 4 days of nicotine treatment induced activation (phosphorylation) of c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase 1 and 2 (ERK1/2) and p38. Inhibition of JNK with its specific inhibitor SP600125 abolished the nicotine-induced effects on kinin receptor-mediated contractions and reverted the enhanced receptor mRNA expression. Administration of phosphodiesterase inhibitors (YM976 and theophylline), glucocorticoid (dexamethasone) or adenylcyclase activator (forskolin) suppressed the nicotine-enhanced airway contractile response to des-Arg⁹-bradykinin and bradykinin.

Conclusions

Nicotine induces airway hyperresponsiveness via transcriptional up-regulation of airway kinin B₁ and B₂ receptors, an effect mediated via neuronal nicotinic receptors. The underlying molecular mechanisms involve activation of JNK- and PDE4-mediated intracellular inflammatory signal pathways. Our results might be relevant to active and passive smokers suffering from airway hyperresponsiveness, and suggest new therapeutic targets for the treatment of smoke-associated airway disease.

Long-term activation of TLR3 by poly(I:C) induces inflammation and impairs lung function in mice

BACKGROUND

The immune mechanisms associated with infection-induced disease exacerbations in asthma and COPD are not fully understood. Toll-like receptor (TLR) 3 has an important role in recognition of double-stranded viral RNA, which leads to the production of various inflammatory mediators. Thus, an understanding of TLR3 activation should provide insight into the mechanisms underlying virus-induced exacerbations of pulmonary diseases.

METHODS

TLR3 knock-out (KO) mice and C57B6 (WT) mice were intranasally administered repeated doses of the synthetic double stranded RNA analog poly(I:C).

RESULTS

There was a significant increase in total cells, especially neutrophils, in BALF samples from poly(I:C)-treated mice. In addition, IL-6, CXCL10, JE, KC, mGCSF, CCL3, CCL5, and TNFalpha were up regulated. Histological analyses of the lungs revealed a cellular infiltrate in the interstitium and epithelial cell hypertrophy in small bronchioles. Associated with the pro-inflammatory effects of poly(I:C), the mice exhibited significant impairment of lung function both at baseline and in response to methacholine challenge as measured by whole body plethysmography and an invasive measure of airway resistance. Importantly, TLR3 KO mice were protected from poly(I:C)-induced changes in lung function at baseline, which correlated with milder inflammation in the lung, and significantly reduced epithelial cell hypertrophy.

CONCLUSION

These findings demonstrate that TLR3 activation by poly(I:C) modulates the local inflammatory response in the lung and suggest a critical role of TLR3 activation in driving lung function impairment. Thus, TLR3 activation may be one mechanism through which viral infections contribute toward exacerbation of respiratory disease.

Double-stranded RNA increases kinin B1 receptor expression and function in human airway epithelial cells

Increased levels of kinins have been detected within the airways during upper respiratory viral infections (URIs). Rhinovirus, the major URI associated with acute exacerbations of asthma, is an ssRNA virus that primarily infects the airway epithelium and produces dsRNA during replication. We asked whether dsRNA could increase the expression of kinin receptors in airway epithelial cells, thereby potentiating the inflammatory consequences of kinin generation. Human airway epithelial cell line BEAS-2B was stimulated with the dsRNA analog Poly I:C and kinin receptor expression detected by quantitative RT-PCR as well as radioligand binding. Poly I:C induced an increase in B1 and B2 receptor mRNA levels in BEAS-2B and primary human normal bronchial epithelial cells. At the cell surface, only B1 receptor expression was increased by Poly I:C. Furthermore, pretreatment of BEAS-2B cells with Poly I:C enhanced the induction of phospho-ERK following B1 receptor ligand stimulation. To investigate whether these finding had potential in vivo relevance, we assessed B1 receptor expression in nasal tissue obtained from 8 normal human subjects with URIs and 3 control subjects. Five of the URI subjects demonstrated increased B1 receptor mRNA compared to the 3 control subjects. We suggest that increased expression of B1 receptor in the human airway following a URI could increase the risk of an exacerbation of asthma by contributing to increased inflammation in the airway.

Sleep apnea is associated with bronchial inflammation and continuous positive airway pressure-induced airway hyperresponsiveness

BACKGROUND

Obstructive sleep apnea syndrome (OSA) is associated with systemic and upper airway inflammation. Pharyngeal inflammation has a potential role in upper airway collapse, whereas systemic inflammation relates to cardiovascular morbidity. However, the presence of an inflammatory involvement of lower airway has been poorly investigated.

OBJECTIVE

The aim of the study was to demonstrate an inflammatory process at the bronchial level in patients with OSA and to analyze effects of continuous positive airway pressure (CPAP) application and humidification on bronchial mucosa.

METHODS

The study was conducted by using sequential induced sputum for cell analysis and IL-8 production, nitric oxide exhalation measurement, and methacholine challenge before and after CPAP.

RESULTS

Bronchial neutrophilia and a high IL-8 concentration were observed in untreated OSA compared with controls (75% +/- 20% vs 43% +/- 12%, P < .05; and 25.02 +/- 9.43 ng/mL vs 8.6 +/- 3.7 ng/mL, P < .001, respectively). IL-8 in sputum supernatant was correlated to apnea hypopnea index (P < .01; r = 0.81). After 1 month of CPAP, this inflammatory pattern remained unchanged, and an increase in airway hyperresponsiveness (AHR) was observed (P < .001).

CONCLUSION

Obstructive sleep apnea syndrome is associated with bronchial inflammation. Our data demonstrate CPAP effect on the development of AHR, possibly facilitated by the pre-existing inflammation. Both issues should be evaluated during long-term CPAP use.

CLINICAL IMPLICATIONS

Results showing a spontaneous bronchial inflammation in OSA and the development of a CPAP-related AHR require a long-term follow-up to evaluate consequences on chronic bronchial obstruction.

IL-1beta-induced transcriptional up-regulation of bradykinin B1 and B2 receptors in murine airways

Hyperresponsiveness to bronchoconstrictor stimuli is a major pathophysiologic feature of asthma, but the molecular mechanisms behind this are not fully understood. The release of TNF-alpha and IL-1beta during the inflammatory process is believed to play an important role in airway hyperresponsiveness. We have previously demonstrated, using a murine in vitro model of chronic airway inflammation, that TNF-alpha up-regulated bradykinin B(1) and B(2) receptors in the airway smooth muscle. By using the same model, the present study was designed to investigate the effects of IL-1beta and its interaction with TNF-alpha on the expression of bradykinin B(1) and B(2) receptors in mouse tracheal smooth muscle. IL-1beta up-regulated bradykinin B(1) and B(2) receptor expression and increased contractile response to bradykinin B(1) and B(2) receptor agonists (des-Arg(9)-bradykinin and bradykinin, respectively) in the tracheal smooth muscle. Transcriptional inhibitor actinomycin D, c-Jun N-terminal kinase (JNK) inhibitors SP600125 and TAT-TI-JIP(153-163), but not extracellular signal-regulated kinase 1 and 2 (ERK 1/2) inhibitor PD98059, significantly attenuated this up-regulation, indicating that a transcriptional mechanism and intracellular JNK signal transduction pathway were involved. In addition, IL-1beta did not affect bradykinin B(1) and B(2) receptor mRNA stability. Remicade, an anti-TNF-alpha antibody, markedly suppressed IL-1beta-induced up-regulation of bradykinin B(1) and B(2) receptors, suggesting that TNF-alpha was involved in the up-regulation, which is further supported by the fact that IL-1beta enhanced TNF-alpha mRNA expression in the tracheae. Intracellular JNK pathway and TNF-alpha might provide key links between inflammatory mediators like IL-1beta and airway hyperresponsiveness to bradykinin.

Non-peptide antagonists for kinin B1 receptors: new insights into their therapeutic potential for the management of inflammation and pain

Kinin B1 and B2 receptors are central to the aetiology of pain and inflammation. Constitutive B2 receptors are commonly associated with the acute phase of inflammation and nociception, whereas the inducible B1 receptors are mostly linked to the chronic or persistent phase (or both). Therefore, selective, orally active kinin B1 receptor antagonists could be potentially therapeutic. B1 receptor antagonists have long been exclusively peptides, but recently a few non-peptide representatives have been identified. The clinical potential of these non-peptide molecules has not yet been evaluated, but they might have a role in treating persistent inflammation and pain, especially when no satisfactory therapy is available. This review summarizes recent advances in the identification and the potential therapeutic properties of these molecules.

Effect of novel selective non-peptide kinin B(1) receptor antagonists on mouse pleurisy induced by carrageenan

Two novel selective non-peptide kinin B(1) receptor antagonists, the benzodiazepine antagonist and SSR240612, were evaluated in carrageenan-induced mouse pleurisy. The peptide R-715 (0.5 mg/kg, i.p.) and the non-peptide benzodiazepine (3 mg/kg, i.p.) antagonists significantly decreased cellular migration (predominantly neutrophils), without altering plasma exudation. SSR240612 (1 mg/kg, i.p.) diminished total cells and neutrophils, besides exudation. Oral administration of SSR240612 (10 mg/kg) also reduced total cell and neutrophil counts. Only the benzodiazepine antagonist inhibited the lung myeloperoxidase activity. No tested antagonist significantly altered the lung and pleural TNFalpha and IL-1beta production. We provide interesting evidence on the anti-inflammatory in vivo effects of non-peptide B(1) receptor antagonists.

Peptide and non-peptide bradykinin receptor antagonists: role in allergic airway disease

Kinins are proinflammatory peptides that mediate a variety of pathophysiological responses. These actions occur through stimulation of two pharmacologically distinct receptor subtypes B1 and B2. In both human and animal airways, the majority of kinin-induced effects including bronchoconstriction, increases in vascular permeability and mucus secretion and cholinergic and sensory nerve stimulation appear to be bradykinin B2-receptor mediated. Peptidic and non-peptidic receptor antagonists have been developed as potential therapeutic agents. These antagonists are effective in blocking kinin-induced effects in a variety of animal models and in some instances, have been used effectively in animal models of allergic airway disease to alleviate allergen-induced pathophysiological airway responses. This review summarizes relevant studies supporting the evidence that bradykinin B2 receptor antagonism and/or upstream inhibition of tissue kallikrein will be beneficial in the treatment of inflammatory airway diseases.

TGF-beta potentiates airway smooth muscle responsiveness to bradykinin

The molecular mechanisms by which bradykinin induces excessive airway obstruction in asthmatics remain unknown. Transforming growth factor (TGF)-beta has been involved in regulating airway inflammation and remodeling in asthma, although it is unknown whether TGF-beta can modulate bradykinin-associated bronchial hyperresponsiveness. To test whether TGF-beta directly modulates airway smooth muscle (ASM) responsiveness to bradykinin, isolated murine tracheal rings were used to assess whether TGF-beta alters ASM contractile responsiveness to bradykinin. Interestingly, we found TGF-beta-treated murine rings (12.5 ng/ml, 18 h) exhibited increased expression of bradykinin 2 (B(2)) receptors and became hyperreactive to bradykinin, as shown by increases in maximal contractile responses and receptor distribution. We investigated the effect of TGF-beta on bradykinin-evoked calcium signals since calcium is a key molecule regulating ASM excitation-contraction coupling. We reported that TGF-beta, in a dose- (0.5-10 ng/ml) and time- (2-24 h) dependent manner, increased mRNA and protein expression of the B(2) receptor in cultured human ASM cells. Maximal B(2) receptor protein expression that colocalized with CD44, a marker of membrane cell surface, occurred after 18 h of TGF-beta treatment and was further confirmed using fluorescence microscopy. TGF-beta (2.5 ng/ml, 18 h) also increased bradykinin-induced intracellular calcium mobilization in fura-2-loaded ASM cells. TGF-beta-mediated enhancement of calcium mobilization was not attenuated with indomethacin, a cyclooxygenase inhibitor. These data demonstrate for the first time that TGF-beta may play a role in mediating airway hyperresponsiveness to bradykinin seen in asthmatics by enhancing ASM contractile responsiveness to bradykinin, possibly as a result of increased B(2) receptor expression and signaling.

International union of pharmacology. XLV. Classification of the kinin receptor family: from molecular mechanisms to pathophysiological consequences

Kinins are proinflammatory peptides that mediate numerous vascular and pain responses to tissue injury. Two pharmacologically distinct kinin receptor subtypes have been identified and characterized for these peptides, which are named B1 and B2 and belong to the rhodopsin family of G protein-coupled receptors. The B2 receptor mediates the action of bradykinin (BK) and lysyl-bradykinin (Lys-BK), the first set of bioactive kinins formed in response to injury from kininogen precursors through the actions of plasma and tissue kallikreins, whereas the B(1) receptor mediates the action of des-Arg9-BK and Lys-des-Arg9-BK, the second set of bioactive kinins formed through the actions of carboxypeptidases on BK and Lys-BK, respectively. The B2 receptor is ubiquitous and constitutively expressed, whereas the B1 receptor is expressed at a very low level in healthy tissues but induced following injury by various proinflammatory cytokines such as interleukin-1beta. Both receptors act through G alpha(q) to stimulate phospholipase C beta followed by phosphoinositide hydrolysis and intracellular free Ca2+ mobilization and through G alpha(i) to inhibit adenylate cyclase and stimulate the mitogen-activated protein kinase pathways. The use of mice lacking each receptor gene and various specific peptidic and nonpeptidic antagonists have implicated both B1 and B2 receptors as potential therapeutic targets in several pathophysiological events related to inflammation such as pain, sepsis, allergic asthma, rhinitis, and edema, as well as diabetes and cancer. This review is a comprehensive presentation of our current understanding of these receptors in terms of molecular and cell biology, physiology, pharmacology, and involvement in human disease and drug development.

Potentiation of des-Arg9-Kallidin-Induced Vasoconstrictor Responses by Metallopeptidase Inhibition in Isolated Human Umbilical Artery

Several metallopeptidases have been reported to be involved in bradykinin (BK) B(1) receptor agonist metabolism. Our goal was to evaluate in vitro roles of metallopeptidases [e.g., neutral endopeptidase (NEP), aminopeptidase M (APM), and angiotensin-converting enzyme (ACE)] as functional inactivators of the selective BKB(1) receptor agonist Lys-des-Arg(9)-BK (DAKD) in isolated human umbilical artery (HUA) rings. Concentration-response curves (CRCs) to DAKD were performed after a 5-h incubation period. Treatment with 10 microM phosphoramidon (NEP inhibitor) or 10 microM amastatin (APM inhibitor) potentiated DAKD-elicited responses, whereas 1 microM captopril (ACE inhibitor) had no significant effects. However, when the three enzymes were simultaneously inhibited, a significant potentiation over responses obtained under concurrent NEP and aminopeptidase M inhibition was observed. In contrast, responses induced by the peptidase resistant BKB(1) receptor agonist Sar-D-Phe(8)-des-Arg(9)-BK were not modified by triple peptidase inhibition. In addition, endothelial denudation failed to alter DAKD-induced responses in HUA. Finally, in the presence of NEP, ACE, and APM inhibition, Lys-des-Arg(9)-[Leu(8)]-BK, the potent BKB(1) receptor antagonist, produced a parallel, concentration-dependent, rightward shift of DAKD CRCs. The obtained pK(B) (8.57) and the Schild slope not different from unity are in agreement with an interaction at a single homogeneous BKB(1) receptor population. In summary, this work constitutes the first pharmacological evidence that metallopeptidases NEP, APM, and ACE represent a relevant inactivation mechanism of the endogenous BKB(1) receptor agonist DAKD in isolated HUA.

Infection-Induced Kinin B1Receptors in Human Pulmonary Fibroblasts: Role of Intact Pathogens and p38 Mitogen-Activated Protein Kinase-Dependent Signaling

Kinin B(1) receptors (B(1)R) are involved in many pathophysiological processes, and its expression is up-regulated in inflammatory pulmonary disease. Although bacteria can generate kinin peptides, the molecular signaling mechanisms regulating B(1)R during infection by intact pathogens is unknown. The serious opportunistic clinical isolate Burkholderia cenocepacia (B. cen.) belongs to the important B. cepacia complex (Bcc) of gram-negative pathogens that rapidly causes fatal pulmonary disease in hospitalized and immunocompromised patients and those with cystic fibrosis. We demonstrate here that B. cen. infection induced a rapid increase in B(1)R mRNA (1 h) proceeded by an increase in B(1)R protein expression (2 h), without affecting B(2) receptor expression in human pulmonary fibroblasts. The B(1)R response was dose-dependent and maximal by 6 to 8 h (3- to 4-fold increase), however, brief B. cen. infection could sustain B(1)R up-regulation. In contrast, nonclinical Bcc phytopathogens were much less B(1)R inducive. The protein synthesis inhibitor cycloheximide and transcriptional inhibitor actinomycin D abrogated the B(1) response to B. cen. indicating de novo B(1)R synthesis. B. cen. activated p38 mitogen-activated protein kinase (MAPK), and blocking p38 MAPK with the specific inhibitor 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB 203580) dramatically reduced B. cen.-induced B(1)R. Furthermore, B. cen. regulation of B(1)R was diminished by the anti-inflammatory glucocorticoid dexamethasone. In conclusion, this study is the first demonstration that infection with intact pulmonary pathogens like B. cen. positively modulates the selective expression of B(1)R. Thus, providing evidence that B(1)R regulation may be an important and novel mechanism in the inflammatory cascade in response to chronic pulmonary infection and disease.

Kinin B1 receptors: key G-protein-coupled receptors and their role in inflammatory and painful processes

Kinins are a family of peptides implicated in several pathophysiological events. Most of their effects are likely mediated by the activation of two G-protein-coupled receptors: B(1) and B(2). Whereas B(2) receptors are constitutive entities, B(1) receptors behave as key inducible molecules that may be upregulated under some special circumstances. In this context, several recent reports have investigated the importance of B(1) receptor activation in certain disease models. Furthermore, research on B(1) receptors in the last years has been mainly focused in determining the mechanisms and pathways involved in the process of induction. This was essentially favoured by the advances obtained in molecular biology studies, as well as in the design of selective and stable peptide and nonpeptide kinin B(1) receptor antagonists. Likewise, development of kinin B(1) receptor knockout mice greatly helped to extend the evidence about the relevance of B(1) receptors during pathological states. In the present review, we attempted to remark the main advances achieved in the last 5 years about the participation of kinin B(1) receptors in painful and inflammatory disorders. We have also aimed to point out some groups of chronic diseases, such as diabetes, arthritis, cancer or neuropathic pain, in which the strategic development of nonpeptidic oral-available and selective B(1) receptor antagonists could have a potential relevant therapeutic interest.

Up-regulation of bradykinin receptors in a murine in-vitro model of chronic airway inflammation

Tumour necrosis factor-alpha (TNF-alpha) is a mediator with a likely role in chronic airway inflammation and airway hyperresponsiveness. In the present study, mouse tracheal segments were cultured for 1, 4 or 8 days in the absence and presence of TNF-alpha. Contractile response of cultured segments to des-Arg9-bradykinin and bradykinin was assessed in myographs and mRNA for bradykinin B1 and B2 receptors was quantified by real-time polymerase chain reaction. Both contraction to des-Arg9-bradykinin and bradykinin, mediated via bradykinin B1 and B2 receptors, respectively, and mRNA levels for these receptors were up-regulated following culture. These responses were markedly increased in segments treated with TNF-alpha. Experiments with SP600125 (anthrax(1,9-cd)pyrazol-6(2H)-one) and PD98059 (2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one) demonstrated that both intracellular c-Jun N-terminal kinase and extracellular signal-regulated kinase 1/2 pathways were implicated in this process. Thus, TNF-alpha causes an increase of bradykinin contractility in mouse trachea, which at least partly is due to a transcriptional increase of bradykinin receptors.

Airway hyperresponsiveness to bradykinin induced by allergen challenge in actively sensitised Brown Norway rats

The mechanism(s) of bradykinin-induced bronchoconstriction was investigated in the Brown Norway (BN) rat model of allergic asthma. Bronchoconstrictor responses to i.v. bradykinin in BN rats were maximally augmented 24 h following challenge with allergen and declined at later time points. Histological evaluation of the inflammatory status of the lungs after ovalbumin (OA) challenge showed a marked inflammatory response, which was maximal at 24 h and declined thereafter. However, pretreatment with budesonide did not inhibit the augmented bronchoconstrictor response to bradykinin 24 h after allergen challenge. The selective B1 receptor agonist, Lys-[desArg9]-BK had no bronchoconstrictor effects, whereas the selective B2 receptor antagonist, HOE 140, abolished the response to bradykinin in OA-challenged animals. The augmented response to bradykinin was not affected by methysergide, indomethacin, disodium cromoglycate, iralukast, the 5-lipoxygenase inhibitor, CGS8515, or the NK2 receptor antagonist, SR48968. It was, however, partially inhibited by atropine both in saline- and OA-challenged animals. Pretreatment with captopril and thiorphan markedly potentiated responses to bradykinin both in saline- and OA-challenged animals. Thus, augmentation of the bronchoconstrictor response to bradykinin occurs in actively sensitised BN rats 24 h after challenge with OA and is associated with marked pulmonary inflammation. The response is entirely B2 receptor mediated and approximately 50% of the response is cholinergic. However, mast cell activation, the products of the cyclooxygenase or 5-lipoxygenase pathways and tachykinins are not involved. Peptidase inhibition mimics the effect of allergen challenge on the bronchoconstrictor response to bradykinin and it remains possible that the mechanism of the augmented response to bradykinin following allergen challenge involves downregulation of peptidase activity as a consequence of the inflammatory response.

Kinins are involved in the development of allergic nasal hyperresponsiveness in guinea pigs

We evaluated roles of kinins in allergen-induced nasal blockage and sneezing, and development of nasal hyperresponsiveness to leukotriene D4 in a Japanese cedar pollen-induced allergic rhinitis model of guinea pigs. Sensitised guinea pigs were repeatedly challenged by pollen inhalation once every week. Neither a bradykinin B1 receptor antagonist, des-Arg9-[Leu8]bradykinin nor a bradykinin B2 receptor antagonist, icatibant suppressed allergen-induced sneezing and nasal blockage. However, development of nasal hyperresponsiveness to leukotriene D4 was significantly suppressed by them. The amount of bradykinin in nasal cavity lavage fluid was immediately increased after the challenge. In non-sensitised animals, hyperresponsiveness to leukotriene D4 was developed by a bradykinin B2 receptor agonist, bradykinin, but not by a bradykinin B1 receptor agonist, des-Arg10-kallidin, while in the sensitised-challenged animal, both agonists developed hyperresponsiveness. In conclusion, the nasal hyperresponsiveness appeared to be induced by kinins produced in response to the antigen challenge through activation of not only bradykinin B2 but also B1 receptors.

Functional characterization and biomarker identification in the Brown Norway model of allergic airway inflammation

1. The antigen-induced inflammatory response in the Brown Norway rat is a model commonly used to assess the impact of novel compounds on airway eosinophilia. A detailed functional, cellular and molecular characterization of this model has not yet been performed within a single study. This information together with the temporal changes in this phenomenon should be known before this model can be used, with confidence, to elucidate the mechanisms of action of novel anti-inflammatory drugs. 2. Antigen challenge caused an accumulation of eosinophils in lung tissue 24 h after challenge. Accumulation of CD2(+) T cells was not apparent until after 72 h. 3. Interestingly, mRNA for the Th2 type cytokines interleukin (IL)-4, IL-5 and IL-13 and eotaxin were elevated in lung tissue after challenge and the expression of IL-13 and eotaxin protein increased at around 8-12 h. The temporal changes in both the biomarker production and the functional responses are important factors to consider in protocol design prior to initiating a compound screening program. 4. A neutralising antibody (R73) against alphabeta-TCR caused a significant reduction in T cell numbers accompanied by a significant suppression of eosinophil accumulation. 5. Airway hyperreactivity (AHR) was not apparent in this specific Brown Norway model in sensitized animals after a single or multiple challenges although eosinophil influx was seen in the same animals. 6. In conclusion, this is a convenient pre-clinical model (incorporating the measurement of biomarkers and functional responses) for screening novel small molecule inhibitors and/or biotherapeutics targeted against T cell/eosinophil infiltration/activation.

Up-regulation of functional kinin B1 receptors in allergic airway inflammation

B1 receptors are known to be induced during allergic airway inflammation in animal models. However, little is known regarding in vivo B1 receptor expression in humans. We examined B1 receptor mRNA expression in nasal tissue samples from allergic rhinitis and normal subjects. Allergic rhinitis subjects displayed significantly higher expression of B1 receptor mRNA than did the normal subjects, and nasal allergen challenge increased B1 receptor mRNA expression at 8 to 24 h time points in allergic rhinitis subjects. No significant difference was found in B2 receptor expression. To confirm B2 and B1 receptor functional activity, subjects were challenged with kinin agonists. Nasal challenge with the B1 receptor ligand, Lys-des-Arg-bradykinin (BK), activated extracellular signal-regulated kinase in allergic rhinitis, but not normal, subjects. Nasal challenge with the B2 receptor ligand, BK, activated extracellular signal-regulated kinase in both allergic rhinitis and normal subjects. The consequences of B1 receptor activation were investigated using the human airway epithelial cell lines A549 and BEAS-2B. We demonstrated that Lys-des-Arg-BK activates the transcription factor AP-1. Taken together, these results show that functional B1 receptors are induced in the airway during allergic inflammation and suggest that they participate in the regulation of gene expression.

Regulation of kinin receptors in airway epithelial cells by inflammatory cytokines and dexamethasone

The two kinin receptors, B(1) and B(2), are upregulated in inflammation and may play a role in diseases such as asthma. In pulmonary A549 cells, TNF-alpha or interleukin-1 beta dramatically increased bradykinin B(1) and B(2) receptor mRNA expression and this response was prevented by dexamethasone. In primary human bronchial epithelial cells, bradykinin B(1) receptor mRNA expression showed a similar trend, whereas bradykinin B(2) receptor showed almost constitutive expression. Radioligand-binding studies revealed significant increases in bradykinin B(2) receptor protein expression following both interleukin-1 beta and TNF-alpha treatment of A549 cells; however, no evidence was found for bradykinin B(1) receptor. Functionally, the bradykinin B(2) receptor ligand, bradykinin, but not the B(1) ligand, des-Arg(10)-kallidin, produced a marked increase in prostaglandin E(2) release when administered following interleukin-1 beta treatment. Arachidonic acid release in response to bradykinin was markedly enhanced by prior incubation with interleukin-1 beta and this was prevented by the prior addition of dexamethasone.

Species differences in bradykinin receptor-mediated responses of the airways

1. Bradykinin (BK) is a nine amino acid peptide (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) formed from the plasma precursor kininogen during inflammation and tissue injury. The actions of BK are mediated by G protein-coupled cell surface receptors, designated B1 and B2. 2. BK has a plethora of effects in the airways including bronchoconstriction, bronchodilation, stimulation of cholinergic and sensory nerves, mucus secretion, cough and oedema resulting from promotion of microvascular leakage. These airway effects are mediated in the main by the B2 receptor subtype. 3. BK acts mainly indirectly, primarily through airway nerve activation, but also by the release of prostanoids, thromboxanes and nitric oxide (NO). 4. Airway responses to BK have been studied in detail in guinea-pigs, mice, sheep and rats. This review describes the effects of BK in these species and draws comparison with its effects in normal humans and patients with respiratory diseases. 5. Despite its many and varied effects in the airways of animals and man, the exact contribution of BK to airways disease remains unclear.

Pathways for bradykinin formation and inflammatory disease

Bradykinin is formed by the interaction of factor XII, prekallikrein, and high-molecular-weight kininogen on negatively charged inorganic surfaces (silicates, urate, and pyrophosphate) or macromolecular organic surfaces (heparin, other mucopolysaccharides, and sulfatides) or on assembly along the surface of cells. Catalysis along the cell surface requires zinc-dependent binding of factor XII and high-molecular-weight kininogen to proteins, such as the receptor for the globular heads of the C1q subcomponent of complement, cytokeratin 1, and urokinase plasminogen activator receptor. These 3 proteins complex together within the cell membrane, and initiation depends on autoactivation of factor XII on binding to gC1qR (the receptor for the globular heads of the C1q subcomponent of complement). There is also a factor XII-independent bypass mechanism requiring a cell-derived cofactor or protease that activates prekallikrein. Bradykinin is degraded by carboxypeptidase N and angiotensin-converting enzyme. Angioedema that is bradykinin dependent results from hereditary or acquired C1 inhibitor deficiencies or use of angiotensin-converting enzyme inhibitors to treat hypertension, heart failure, diabetes, or scleroderma. The role for bradykinin in allergic rhinitis, asthma, and anaphylaxis is to contribute to tissue hyperresponsiveness, local inflammation, and hypotension. Activation of the plasma cascade occurs as a result of heparin release and endothelial-cell activation and as a secondary event caused by other pathways of inflammation.

Interactive contribution of NK(1) and kinin receptors to the acute inflammatory oedema observed in response to noxious heat stimulation: studies in NK(1) receptor knockout mice

1. Scald injury in Sv129+C57BL/6 mice induced a temperature and time dependent oedema formation as calculated by the extravascular accumulation of [(125)I]-albumin. Oedema formation was suppressed in NK(1) knockout mice compared to wildtypes at 10 (P<0.01) and 30 min (P<0.001). However, at 60 min a similar degree of extravasation was observed in the two groups. 2. Kinin B(1) (des-Arg(10) Hoe 140; 1 micromol kg(-1)) and B(2) (Hoe 140; 100 nmol kg(-1)) antagonists caused an inhibition of oedema in wildtype mice at 10 and 30 min (P<0.001), but not at 60 min or at 30 min in NK(1) receptor knockout mice. 3. The inhibition of thermic oedema by des-Arg(10) Hoe 140 was reversed by des-Arg(9) bradykinin (0.1 micromol kg(-1); P<0.01) and also observed with a second B(1) receptor antagonist (des-Arg(9) Leu(8) bradykinin; 3 micromol kg(-1); P<0.01). Furthermore des-Arg(10) Hoe 140 had no effect on capsaicin (200 microg ear(-1)) ear oedema, but this was significantly reduced with Hoe 140 (P<0.05). 4. Scalding induced a large neutrophil accumulation at 4 h, as assessed by myeloperoxidase assay (P<0.001). This was not suppressed by NK(1) receptor deletion or kinin antagonists. 5. These results confirm an essential role for the NK(1) receptor in mediating the early, but not the delayed phase of oedema formation or neutrophil accumulation in response to scalding. The results also demonstrate a pivotal link between the kinins and sensory nerves in the microvascular response to burn injury, and for the first time show a rapid involvement of the B(1) receptor in murine skin.