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While coronavirus disease 2019 (COVID-19) begins as a respiratory infection, it progresses as a systemic disease involving multiorgan microthromboses that underly the pathology. SARS-CoV-2 enters host cells via attachment to the angiotensin-converting enzyme 2 (ACE2) receptor. ACE2 is widely expressed in a multitude of tissues, including the lung (alveolar cells), heart, intestine, kidney, testis, gallbladder, vasculature (endothelial cells), and immune cells. Interference in ACE2 signaling could drive the aforementioned systemic pathologies, such as endothelial dysfunction, microthromboses, and systemic inflammation, that are typically seen in patients with severe COVID-19. ACE2 is a component of the renin–angiotensin system (RAS) and is intimately associated with the plasma kallikrein-kinin system (KKS). As many papers are published on the role of ACE and ACE2 in COVID-19, we will review the role of bradykinin, and more broadly the KSS, in SARS-CoV-2-induced vascular dysfunction. Furthermore, we will discuss the possible therapeutic interventions that are approved and in development for the following targets: coagulation factor XII (FXII), tissue kallikrein (KLK1), plasma kallikrein (KLKB1), bradykinin (BK), plasminogen activator inhibitor (PAI-1), bradykinin B1 receptor (BKB1R), bradykinin B2 receptor (BKB2R), ACE, furin, and the NLRP3 inflammasome. Understanding these targets may prove of value in the treatment of COVID-19 as well as in other virus-induced coagulopathies in the future. [ABSTRACT FROM AUTHOR]

As of April 20, 2020, over time, the COVID‐19 pandemic has resulted in 157 970 deaths out of 2 319 066 confirmed cases, at a Case Fatality Rate of ~6.8%. With the pandemic rapidly spreading, and health delivery systems being overwhelmed, it is imperative that safe and effective pharmacotherapeutic strategies are rapidly explored to improve survival. In this paper, we use established and emerging evidence to propose a testable hypothesis that, a vicious positive feedback loop of des‐Arg(9)‐bradykinin‐ and bradykinin‐mediated inflammation → injury → inflammation, likely precipitates life threatening respiratory complications in COVID‐19. Through our hypothesis, we make the prediction that the FDA‐approved molecule, icatibant, might be able to interrupt this feedback loop and, thereby, improve the clinical outcomes. This hypothesis could lead to basic, translational, and clinical studies aimed at reducing COVID‐19 morbidity and mortality. [ABSTRACT FROM AUTHOR]

Skeletal muscle tissue retains a remarkable regenerative capacity due to the activation of resident stem cells that in pathological conditions or after tissue damage proliferate and commit themselves into myoblasts. These immature myogenic cells undergo differentiation to generate new myofibers or repair the injured ones, giving a strong contribution to muscle regeneration. Cytokines and growth factors, potently released after tissue injury by leukocytes and macrophages, are not only responsible of the induction of the initial inflammatory response, but can also affect skeletal muscle regeneration. Growth factors exploit sphingosine kinase (SK), the enzyme that catalyzes the production of sphingosine 1-phosphate (S1P), to exert their biological effects in skeletal muscle. In this paper we show for the first time that bradykinin (BK), the leading member of kinin/kallikrein system, is able to induce myogenic differentiation in C2C12 myoblasts. Moreover, evidence is provided that SK1, the specific S1P-transporter spinster homolog 2 (Spns2) and S1P 2 receptor are involved in the action exerted by BK, since pharmacological inhibition/antagonism or specific down-regulation significantly alter BK-induced myogenic differentiation. Moreover, the molecular mechanism initiated by BK involves a rapid translocation of SK1 to plasma membrane, analyzed by time-lapse immunofluorescence analysis. The present study highlights the role of SK1/Spns2/S1P receptor 2 signaling axis in BK-induced myogenic differentiation, thus confirming the crucial involvement of this pathway in skeletal muscle cell biology. [ABSTRACT FROM AUTHOR]

Prolyl peptidases of the MEROPS S28 family are of particular interest because they are key enzymes in the digestion of proline-rich peptides. A BLAST analysis of the Aspergillus oryzae genome revealed sequences coding for four proteases of the S28 family. Three of these proteases, AoS28A, AoS28B, and AoS28C, were previously characterized as acidic prolyl endopeptidases. The fourth protease, AoS28D, showed high sequence divergence with other S28 proteases and belongs to a phylogenetically distinct cluster together with orthologous proteases from other Aspergillus species. The objective of the present paper was to characterize AoS28D protease in terms of substrate specificity and activity. AoS28D produced by gene overexpression in A. oryzae and in Pichia pastoris was a 70-kDa glycoprotein with a 10-kDa sugar moiety. In contrast with other S28 proteases, AoS28D did not hydrolyze internal Pro-Xaa bonds of several tested peptides. Similarly, to human lysosomal Pro-Xaa carboxypeptidase, AoS28D demonstrated selectivity for cleaving C-terminal Pro-Xaa bonds which are resistant to carboxypeptidases of the S10 family concomitantly secreted by A. oryzae. Therefore, AoS28D could act in synergy with these enzymes during sequential degradation of a peptide from its C-terminus. [ABSTRACT FROM AUTHOR]

The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manu­script met the ICMJE "uniform requirements" for biomedical papers. [ABSTRACT FROM AUTHOR]

Abstract: In a previous paper we showed that bradykinin (BK), interacting with its B2 receptor, inhibits proximal tubule Na+-ATPase activity but does not change (Na+ +K+)ATPase activity. The aim of this paper was to investigate the molecular mechanisms involved in B2-mediated modulation of proximal tubule Na+-ATPase by BK. To abolish B1 receptor-mediated effects, all experiments were carried out in the presence of (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Leu), des-Arg9-[Leu8]-BK (DALBK), a specific antagonist of B1 receptor. A dual effect on the Na+-ATPase activity through the B2 receptor was found: short incubation times (1–10 min) stimulate the enzyme activity; long incubation times (10–60 min) inhibit it. The stimulatory effect of BK is mediated by activation of phosphoinositide-specific phospholipase C β (PI-PLCβ)/protein kinase C (PKC); its inhibitory action is mediated by Ca2+-independent phospholipase A2 (iPLA2). Prior activation of the PI-PLCβ/PKC pathway is required to activate the iPLA2-mediated inhibitory phase. These results reveal a new mechanism by which BK can modulate renal sodium excretion: coupling between B2 receptor and activation of membrane-associated iPLA2. [Copyright &y& Elsevier]

In this paper, bradykinin (BK), an endogenous peptide hormone, which is involved in a number of physiological and pathophysiological processes was deposited onto the colloidal Au nanoparticles. The surface-enhanced Raman spectroscopy (SERS) was used to determine the adsorption mode of BK under different environmental conditions, including: excitation wavelengths (514.5 nm and 785.0 nm), pH of aqueous sol solutions (from pH = 3 to pH = 11), and size of the colloidal nanoparticles (10, 20, and 50 nm). The metal surface plasmon of the colloidal suspended Au nanoparticles was examined by ultraviolet-visible (UV–vis) spectroscopy. The results showed that the C -terminal part of BK plays a crucial role in the adsorption process onto the colloidal suspended Au particles. The Phe 5/8 and Arg 9 residues of BK mainly participate in the interactions with the colloidal Au nanoparticles. At acidic pH of the solution (pH = 3), the BK COO − terminal group through the both oxygen atoms strongly binds to the Au nanoparticles. The Phe 5 /Phe 8 rings adopt tilted orientation with respect to the colloidal Au nanoparticles with diameters of 10 and 20 nm. As the particle size increases to 50 nm, the flat orientation of the Phe ring(s) with respect to the Au nanoparticles is observed. [ABSTRACT FROM AUTHOR]

Stroke is the third leading cause of death in the Western world. Ischemic stroke is characterized by a rapid loss of brain function due to disturbance in the blood supply to a part of the brain. Due to fixed intracranial space, any increase in intracranial fluid volume, or progressive brain edema formation, contributes to further deterioration of the already impaired brain function. Bradykinin increases blood-brain barrier permeability and raises intracranial capillary blood pressure by arterial dilatation and venous constriction leading to brain edema formation. The aim of this paper is to summarize the recent research in the field of bradykinin function (structure, synthesis, signaling pathways, mechanism of action) followed by characterization of different types of brain edema development related to ischemic brain injury, together with the involvement of bradykinin in edema formation. Since there is currently no causal treatment addressing brain edema after ischemic stroke, specific bradykinin receptor antagonists are proposed as a possible new therapeutic approach. [ABSTRACT FROM AUTHOR]

Information about several papers discussed at the Bradykinin Symposium 2012 held on August 23-24, 2012 at Charité-Universit&#228tsmedizin Berlin, Germany is presented. Topics include activation of the plasma bradykinin-forming cascade, similarities and differences of the bradykinin in the lung, nose and skin and the animal models of hereditary angioedema (HAE) that is considered to be a clue for the mechanisms and the therapy.

In this paper, the surface-enhanced Raman scattering (SERS) spectra of the potent B2 bradykinin receptor antagonists, [D-Arg0,Hyp3,Thi5,8,L-Pip7]BK, Aaa[D-Arg0,Hyp3,Thi5,8,L-Pip7]BK, [D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK, and Aaa[D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK, were measured when immobilized onto a highly specific electrochemically roughened SERS-active Ag substrate characterized by the formation of a 50 - 150 nm Ag islands on its surface. The observed SERS bands corresponding to different vibrational modes of the molecule, attached to or near Ag, and the variations in these bands resulting from competitive interactions of the functional groups of the peptides with the SERS-active Ag surfaces and reorientation occurring over time of adsorption were analyzed in this study. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the surface-enhanced Raman scattering (SERS) spectra of the potent B2 bradykinin receptor antagonists, [D-Arg0,Hyp3,Thi5,8,L-Pip7]BK, Aaa[D-Arg0,Hyp3,Thi5,8,L-Pip7]BK, [D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK, and Aaa[D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK, were measured when immobilized onto a colloidal assembly of apparently randomly adhering Ag spheres with diameters of approximately 20 - 25 nm. The observed SERS bands corresponding to different vibrational modes of the molecule, attached to or near Ag, and the variations in these bands resulting from competitive interactions of the functional groups of the peptides with the SERS-active Ag surfaces were analyzed in this study. Briefly, it was shown that Pip, in generally in vertical orientation, and Thi, in the edge-on position, relative to the colloidal Ag surface interacted with this surface through their lone electron pairs on the nitrogen and sulfur atoms, respectively. The imide bond of the X-Pro peptide linkage and the guanidine group of Arg were involved in the adsorption process. In addition, it was demonstrated that the specific differences in the amino acid sequences slightly influenced the mode of adsorption. For example, Aaa in Aaa[D-Arg0,Hyp3,Thi5,8,L-Pip7]BK and Aaa[D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK and D-Phe (vertical with respect to the colloidal Ag surface) in [D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK, and Aaa[D-Arg0,Hyp3,Thi5,D-Phe7,L-Pip8]BK assisted in the adsorption of these peptides onto the colloidal Ag particles. To discuss these spectral alterations due to the different surface adsorption mechanisms of these peptides, the spectral changes were analyzed according to the adsorption process and Fourier-transform-Raman spectra. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Cellular membranes have relevant roles in processes related to proteases like human kallikreins and cathepsins. As enzyme and substrate may interact with cell membranes and associated co-factors, it is important to take into account the behavior of peptide substrates in the lipid environment. In this paper we report an study based on energy transfer in two bradykinin derived peptides labeled with the donor-acceptor pair Abz/Eddnp ( ortho-aminobenzoic acid/N-[2,4-dinitrophenyl]-ethylenediamine). Time-resolved fluorescence experiments were performed in phosphate buffer and in the presence of large unilamelar vesicles of phospholipids, and of micelles of sodium dodecyl sulphate (SDS). The decay kinetics were analyzed using the program CONTIN to obtain end-to-end distance distribution functions f(r). Despite of the large difference in the number of residues the end-to-end distance of the longer peptide (9 amino acid residues) is only 20 % larger than the values obtained for the shorter peptide (5 amino acid residues). The proline residue, in position 4 of the bradykinin sequence promotes a turn in the longer peptide chain, shortening its end-to-end distance. The surfactant SDS has a strong disorganizing effect, substantially broadening the distance distributions, while temperature increase has mild effects in the flexibility of the chains, causing small increase in the distribution width. The interaction with phospholipid vesicles stabilizes more compact conformations, decreasing end-to-end distances in the peptides. Anisotropy experiments showed that rotational diffusion was not severely affected by the interaction with the vesicles, suggesting a location for the peptides in the surface region of the bilayer, a result consistent with small effect of lipid phase transition on the peptides conformations. [ABSTRACT FROM AUTHOR]

James Black believed that analysis of biological assays provides insights into the operation of physiological control systems. In this paper, we illustrate this point in three ‘cardiovascular’ assays. The first determined the half-life (t½) of ‘endothelium-derived relaxing factor’ (EDRF), using bradykinin to release EDRF, which produced concentration-related relaxations of a precontracted artery. With the introduction of time delays between the source of EDRF and the assay artery, there were rightward shifts in dose-response curves, which provided the basis of calculating t½. The second assay determined the roles of noradrenaline reuptake and prejunctional α2-adrenoceptor activity on transmitter concentration at sympathetic synapses with atria and resistance vessels. In the former, the reuptake role was paramount, whilst prejunctional receptor activity was dominant at vascular synapses, owing to anatomical differences. The third assay provided in vivo estimates of the enhancement of the total peripheral resistance responses to constrictor and dilator stimuli owing to the structural changes in hypertension. Major nonlinearities in the dose-response curve obscured this enhancement. Their effect was avoided by deriving extended dose-response curves from combined constrictor and dilator data, permitting calculation of the enhancement over the range between the nonlinearities. [ABSTRACT FROM AUTHOR]

Selective protein labeling with a small molecular probe is a versatile method for elucidating protein functions in living cells. In this paper, we report a covalent labeling method of tag-fused G-protein coupled receptor (GPCR) proteins expressing on cell surfaces utilizing small functional molecules. This method employs the selective and rapid reaction of a peptide tag and a molecular probe, which comprises the cysteine-containing short CA6D4x2 tag (CAAAAAADDDDGDDDD) and a tetranuclear Zn(ll)-DpaTyr probe containing a reactive ct-chloroacetyl moiety. The covalent labeling of tag-fused GPCRs such as bradykinin receptor (B2R) and acetylcholine receptor (ml AchR) selectively proceeded under physiological conditions during short incubation (10-30 min) with Zn(ll)-DpaTyr probes bearing various functional groups. Labeling with fluorophore-appended Zn(ll)-DpaTyr probes enabled visualization of the GPCRs on the surface of HEK293 cells by fluorescence. Labeling with the biotin-appended probe allowed introduction of a biotin unit into the GPCRs. This biotin label was utilized for fluorescence bioimaging studies and postlabeling blotting analysis of the labeled GPCRs by use of the specific biotin-streptavidin interaction. The utility of this labeling method was demonstrated in several function analyses of GPCRs, such as fluorescence visualization of the stimuli-responsive internalization of GPCRs and pH change in endosomes containing the internalized GPCRs. [ABSTRACT FROM AUTHOR]

Different statistical modeling methods (SMMs) are used for nonlinear system classification and regression. On the basis of Bayesian probabilistic inference, Gaussian process (GP) is preliminarily used in the field of quantitative structure-activity relationship (QSAR) but has not yet been applied to quantitative sequence-activity model (QSAM) of biosystems. This paper proposes the application of GP as an alternative tool for the QSAM modeling of peptides. To investigate the modeling performance of GP, three classical peptide panels were used: Angiotensin-I converting enzyme inhibitory dipeptides, bradykinin-potentiating pentapeptides and cationic antimicrobial pentadecapeptides. On this basis, we made a comprehensive comparison between the GP and some widely used SMMs such as PLS, artificial neural network (ANN) and support vector machine (SVM), and gave the conclusions as follow: (1) for those of structurally complicated peptides, particularly the polypeptides, linear PLS was incapable of capturing all dependences hidden in the peptide systems, (2) even in assistance with the monitoring technique, ANN was inclined to be overtrained in the cases of insufficient number of peptide samples, (3) SVM and GP performed best for the three peptide panels. Moreover, since GP was able to correlate the linear and nonlinear-hybrid relationship, it was slightly superior to SVM at most peptide sets. [ABSTRACT FROM AUTHOR]

Endothelial cells produce NO by activation of constitutive nitric oxide synthase (NOS) and transcription of inducible NOS (iNOS). We have previously shown that melatonin, in the nanomolar range, inhibits activation of constitutive NOS, and in the present paper, we evaluated whether it could interfere with the expression of iNOS, which is activated by lipopolysaccharide (LPS), a major component of gram-negative bacteria cell walls. Primary cultures of rat endothelial cells were loaded with fluorescent probe for NO detection. Nuclear factor kappa B (NF-κB) translocation in endothelial cells elicited by LPS was measured by electromobility shift assay, and the vasodilation of aortic rings was accessed by recording isometric contraction. Melatonin in a micromolar but not in a nanomolar range inhibits the NO production induced by LPS. This effect is not dependent on the activation of G protein-coupled melatonin receptors. The nuclear NF-κB translocation is a process necessary for iNOS transcription, and melatonin also inhibits its translocation. LPS induced vasodilation only in endothelium-intact aortic rings, and melatonin (10 μm) inhibits the vasodilation. Here, we show that concentrations compatible with nocturnal melatonin surge (nm) did not interfere with the activity of iNOS. Considering that micromolar melatonin concentrations could be locally achieved through production by activated immune competent cells, extra-pineal melatonin could have a protective effect against tissue injury. We propose that melatonin blocked the LPS-induced vasodilation by inhibiting the NF-κB pathway. Finally, we propose that the effect of melatonin on vascular reactivity is one of the mechanisms that underlies the protective effect of this indolamine against LPS. [ABSTRACT FROM AUTHOR]

Hereditary angioedema (HAE) is an autosomal dominant disease that manifests as intermittent acute swellings of the skin and mucosal surfaces, which, in the gastrointestinal tract and larynx, may even be fatal. HAE results from functional deficiency of the C1 inhibitor (C1INH) protein, which plays a key role in the classical pathway of complement activation. C1INH is the sole inhibitor of the activated proteases C1r and C1s, and is the major regulator of activated coagulation Factor XII and plasma kallikrein, which limits the generation of the vasoactive peptide bradykinin. In this paper, we report on the genetic analysis of 173 families (including 326 members) with a clinical diagnosis of HAE. Direct sequencing, Southern blotting and quantitative PCR by the MLPA method were used to screen for mutations in C1INH (SERPING1). In 142 families (82.1%), a causative C1INH gene mutation could be identified. A total of 80 novel point mutations of C1INH not published previously were detected in 96 pedigrees (including 172 members). Our results corroborate C1INH (SERPING1) deficiency as a disease of extreme allelic heterogeneity with almost each individual family carrying their own mutation. Routine molecular genetic analysis is an effective way of confirming the clinical diagnosis and identifying mutation carriers early on before any clinical manifestation becomes apparent. It is, therefore, a valuable tool in prevention and adequate treatment of acute and life-threatening oedema. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Symptoms in non-allergic non-infectious perennial rhinitis (NANIPER) are characteristically trigged by non-specific irritants. Hyper-responsiveness to cold dry air has been demonstrated in NANIPER. Bradykinin is a peptide involved in allergic inflammation. Neurally mediated hyper-responsiveness to bradykinin has been demonstrated in allergic rhinitis. The purpose of the present study was to investigate whether hyper-responsiveness to bradykinin is present in NANIPER. Normal subjects ( n = 13) and subjects with NANIPER ( n = 10) were subjected to a nasal bradykinin challenge protocol. Secretory responses were measured using filter paper disks, and congestive responses measured using acoustic rhinometry. Compared to normal subjects, with NANIPER had a greater secretory response to control challenge with Hartman’s solution. On the other hand, the normal ipsilateral secretory and congestive response to bradykinin was absent in NANIPER. Subjects with NANIPER did not demonstrate any evidence of reflex responses to bradykinin, and no evidence of nasal hyper-responsiveness to bradykinin. Hyper-responsiveness to bradykinin is absent in NANIPER. These results suggest that autonomic hyporesponsiveness rather than neural hyper-responsiveness may be an important factor in the etiology of NANIPER. [ABSTRACT FROM AUTHOR]

Abstract: Bradykinin (BK) is involved in a wide variety of pathophysiological processes. Potent BK peptide antagonists can be developed introducing constrained unnatural amino acids, necessary to force the secondary structure of the molecule. In this paper, we report a structure–activity relationship study of two peptide analogues of the potent B2 antagonist HOE 140 by replacing the D-Tic-Oic dipeptide with conformationally constrained dipeptide mimetic β-turn inducers. [Copyright &y& Elsevier]

Abstract: The bradykinin 1 (B1) receptor is upregulated during times of inflammation and is important for maintaining inflamed and chronic pain states. Blocking this receptor has been shown to reverse and/or ameliorate pain and inflammation in animal models. In this report, we describe a new class of B1 receptor antagonists that contain the piperidine acetic acid tetralin core. A structure–activity relationship for these analogs is described in this paper. The most potent compounds from this class have IC50s<20nM in a B1 receptor functional assay. One of these compounds, 13g, shows modest oral bioavailability in rats. [Copyright &y& Elsevier]

It has always been assumed that electrical contact at the capillary outlet is a necessary requirement when coupling capillary electrophoresis (CE) with electrospray ionization mass spectrometry (ESI-MS). In this study, we used a pulled bare-capillary tip as the ES! emitter, but neither was it coated with any electrically conductive materials nor was a high external voltage applied on its outlet. In this paper, we demonstrate that this straightforward approach may be used to generate multiply charged ions of proteins and peptides through electrospray ionization. Our results indicate that peptides and proteins, including bradykinin, cytochrome c, myoglobin, and tryptic digest products that elute from a pulled bare-capybara tip can be detected directly by ESI-MS using the tapered bare- capillary interface. Thus, we have demonstrated that CE and ESI-MS may be combined successfully without the need to modify the outlet of the capillary tip with an electrically contacting material. [ABSTRACT FROM AUTHOR]

Abstract: Novel effects of naturally occurring peptides are continuing to be discovered, and their mechanisms of actions as well as interactions with other substances, organs, and systems have been elucidated. Synthetic analogs may have actions similar or antagonistic to the endogenous peptides, and both the native peptides and analogs have potential as drugs or drug targets. The journal Peptides publishes many leading articles on the structure–activity relationship of peptides as well as outstanding reviews on some families of peptides. Complementary to the reviews, here we extract information from the original papers published during the past five years in Peptides (1999–2003) to summarize the effects of different classes of peptides, their modulation by other chemicals and various pathophysiological states, and the mechanisms by which the effects are exerted. Special attention is given to peptides related to feeding, pain, and other behaviors. By presenting in condensed form the effects of peptides which are essential for systems biology, we hope that this summary of existing knowledge will encourage additional novel research to be presented in Peptides. [Copyright &y& Elsevier]

Cathepsins V and L have high identity and few structural differences. In this paper, we reported a comparative study of the hydrolytic activities of recombinant human cathepsins V and L using fluorescence resonance energy transfer peptides derived from Abz-KLRSSKQ-EDDnp (Abz=ortho-aminobenzoic acid and EDDnp=N-(2,4-dinitrophenyl)ethylenediamine). Five series of peptides were synthesized to map the S3 to subsites. The cathepsin V subsites S1 and S3 present a broad specificity while cathepsin L has preference for positively charged residues. The S2 subsites of both enzymes require hydrophobic residues with preference for Phe and Leu. The and subsites of cathepsins V and L are less specific. Based on these data we designed substrates to explore the electrostatic potential differences of them. Finally, the kininogenase activities of these cathepsins were compared using synthetic human kininogen fragments. Cathepsin V preferentially released Lys-bradykinin while cathepsin L released bradykinin. This kininogenase activity by cathepsins V and L was also observed from human high and low molecular weight kininogens. [Copyright &y& Elsevier]

Recently, we demonstrated that bradykinin (BK) counteracts the stimulatory effect of Ang-(1–7) on the Na+-ATPase activity from basolateral membrane of the proximal tubule through B2 receptor. In the present paper, the signaling pathway involved in the inhibitory response of the Na+-ATPase activity to BK was investigated. The following results indicate that the phospholipase A2 (PLA2)/COX/prostaglandin E (PGE2) pathway is implicated in this process: (1) The inhibitory effect of BK on Ang-(1–7)-stimulated enzyme is abolished in a dose-dependent manner by quinacrine (10−9;-10−6M), a nonspecific PLA2 inhibitor, and by PACOCF3 (10−7M), an inhibitor of a Ca2+-independent PLA2. However, AACOCF3 (2×10−4 M), an inhibitor of the cytosolic PLA2, does not modify the inhibitory effect of BK. (2) The inhibitory effect of BK on the Ang-(1–7)-stimulated enzyme is reversed by cyclooxygenase (COX) inhibitors diclofenac (10−12 M) and indomethacin (10−12 M). (3) PGE2 (10−12–10−5 M) inhibits the Na+-ATPase activity in a dose dependent manner. (4)The inhibitory effects of PGE2 and BK on the Na+-ATPase activity are not cumulative. (5) PGE2 (10−12–10−8 M) counteracts the stimulatory effect of Ang-(1–7) on the enzyme activity in a dose-dependent manner. [Copyright &y& Elsevier]

Peptides that display bradykinin-potentiating activity have been obtained from a number of distinct sources, such as snake venoms, fibrinogen, and casein. This paper describes the characterization of two new peptides generated by tryptic hydrolysis of casein. No homology was found with other known vasoactive or vasopotentiating peptides, especially by the lack of Ile-Pro-Pro motif. The peptides EMPFPK and YPVEPFTE, corresponding to the gamma casein sequence (108-113 and 114-121, respectively), displayed a selective potentiating activity on isolated guinea pig ileum for bradykinin. Besides, the octapeptide YPVEPFTE showed an in vitro competitive inhibitor effect on angiotensin-converting enzyme and thimet oligopeptidase and presented an opiate-like activity, increasing two times the latence time in the hot-plate assay. The results suggest that the isolated bioactive peptides act on conversion and/or inactivation of endogenous peptides by enzymes such as angiotensin-converting enzyme and thimet oligopeptidase by modifying several systemic responses such as blood-pressure regulation and in pain response. [ABSTRACT FROM AUTHOR]

Recently, we demonstrated that angiotensin-(1–7) (Ang-(1–7)) stimulates the Na+-ATPase activity through a losartan-sensitive angiotensin receptor, whereas bradykinin inhibits the enzyme activity through the B2 receptor [Regul. Pept. 91 (2000) 45; Pharmacol. Rev. 32 (1980) 1]. In the present paper, the effect of bradykinin (BK) on Ang-(1–7)-stimulated Na+-ATPase activity was evaluated. Preincubation of Na+-ATPase with 10−9 M Ang-(1–7) increases enzyme activity from 7.9±0.9 to 14.1±1.5 nmol Pi mg−1 min−1, corresponding to an increase of 79% (p<0.05). This effect is reverted by bradykinin in a dose-dependent manner (10−14–10−8 M), reaching maximal inhibitory effect at 10−9 M. Des-Arg9 bradykinin (DABK), an agonist of B1 receptor, at the concentrations of 10−9–10−7 M, does not mimic the BK inhibitory effect, and des-Arg9-[Leu8]-BK (DALBK), a B1 receptor antagonist, at the concentrations of 10−10–10−7 M, does not prevent the inhibitory effect of BK on Ang-(1–7)-stimulated enzyme. On the other hand, HOE 140, an antagonist of B2 receptor, abolishes the inhibitory effect of BK on the Ang-(1–7)-stimulated enzyme in a dose-dependent manner, reaching maximal effect at 10−7 M. Taken together, these data indicate that stimulation of B2 receptors by BK can counteract the stimulatory effect of Ang-(1–7) on the proximal tubule Na+-ATPase activity. [Copyright &y& Elsevier]

Abstract: The present paper describes the synthesis and some pharmacological properties of two new bradykinin analogues containing the ethylene-bridged dipeptide Phe-Phe in their molecules. In a further two peptides this modification was combined with acylation of the N-terminus with 1-adamantaneacetic acid. Finally, we synthesized four analogues by removing the Ser[sup 6] residue from the four peptides mentioned above. The activity of the new analogues was assayed on isolated rat uterus (RUT) and in rat blood pressure tests (BPT). The results clearly indicate that the proposed modification, alone or in combination with other changes, resulted in either a drop in antiuterotonic activity or even in conversion to an agonism. Although this tendency is not so distinct in blood pressure assays, the antagonistic potency of the new analogues is also diminished. Nevertheless, it was demonstrated that the d-amino acid in position 7 which, until recently, was considered necessary for antagonism, may be replaced, together with the amino acid occupying position 8, by a suitable, sterically restricted L,L-dipeptide unit. [ABSTRACT FROM AUTHOR]

In a previous paper, we have shown that bradykinin (Bk) and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulate arachidonic acid release from HEL-30 keratinocytes along a Bk-B2 receptor G-protein-coupled pathway or a protein kinase C-dependent mechanism, respectively. Here we show a cytosolic PLA2 (cPLA2) to be responsible for this effect. This enzyme exhibited a marked acyl-group specificity towards arachidonic acid. It was activated by Ca++ in micromolar concentrations and partially translocated from the cytoplasmic to the membrane fraction upon Ca++ treatment. Translocation was also observed upon treatment of cells with either Bk or TPA. However, only with Bk was a corresponding increase of the cytoplasmic Ca++ level observed, whereas TPA-induced translocation occurred at basal Ca++ concentrations. Indirect evidence for a G protein to be involved in Bk- but not TPA-dependent cPLA2 activation was provided using non-hydrolyzable GTP derivatives. It is concluded that keratinocyte cPLA2 plays a critical role in the initiation by exogenous and endogenous factors of the eicosanoid cascade in skin. [ABSTRACT FROM AUTHOR]

This paper describes the solution conformation of the vasoactive peptide hormone des-Arg9-bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe). 1. By ¹H-NMR spectroscopy we studied des-Arg9-bradykinin and its fragments bradykinin-(1-5), bradykinin-(1-6) in aqueous solution as a function of pH (titration) and in dimethylsulfoxide solution at two ionic states (cation and neutral ion species). 2. The preferred solution conformation which is most strongly stabilized in dimethylsulfoxide in the neutral ion species includes a distorted β-turn II involving the N-terminal sequence of Pro²-Pro²-Gly4-Phe5 and most likely a C7-type bend in the C-terminal part Ser-Pro-Phe. 3. A complete series of analogous ([Alan]des Arg9-bradykinin, with n = 1, 2 . . . 8) was then investigated by circular dichroism and ¹H-NMR spectroscopy in order to study the conformational role played by cach residue and to delineate the local and the long-range effects on conformation brought about by the Xaa→Ala substitutions. Chosen spectral parameters (circular dichroic spectra, chemical shift variations and vicinal coupling constants) characteristics of the preferred solution conformation of the native sequence of des-Arg9-bradykinin are followed from analogue to analogue. The important conformational role of the arginine-1 side chain and its positive charge and the spatial proximity of the N-terminal and C-terminal groups, i.e. the folded structure of the peptide can be inferred from these data. 4. A comparison of the biological activities of the analogues with the conformative pertubatins caused by the chemical alterations shows des-Arg9-bradykinin conformation and receptor affinity to be equally sensitive to single-residue substitutions. The correct orientation of the arginine-1 side chain, the precise geometry of the turn involving residues 2-5 and of the C-terminal Pro-Phe sequence are of primary importance. [ABSTRACT FROM AUTHOR]

Reports of Chagas disease are increasing in non-endemic populations across the globe. Apart from vector eradication and prevention efforts by public health organizations, current pharmacological interventions are sparse and show important side effects. In this issue of the BJP, Andrade et al. elegantly demonstrate a new pharmacological paradigm whereby Trypanosoma cruzi host cell invasion requires significant cross-talk between receptors for kinins and endothelins. It is shown, for example, that acting via both ETA and ETB receptors, endothelin-1 (ET-1) cooperates with the (TLR2/CXCR2/B2 kinin receptor) complex to activate inflammatory processes in response to invading trypomastigotes. This study by Andrade et al. prompts, however, several important questions, summarized in this Commentary, such as the putative role of chymase-dependent production of ET-1, the contentious protective role of ACE inhibitors in Chagasic patients, the unexplored role of de novo formed B1 receptors for kinins triggered by cytokines and the putative role of compartmentalized calcium pools in host cell invasion by trypomastigotes. LINKED ARTICLE This article is a commentary on Andrade et al., pp. 1333-1347 of this issue. To view this paper visit [ABSTRACT FROM AUTHOR]

In order to evaluate the utility of copper surfaces as spray initiators for mass spectrometric ionization sources, it is necessary to establish how efficient and reproducible the methodology is. To do this, a superhydrophobic and bare copper surface were used to ionize the singly and doubly charged peptides, bradykinin and leucine-enkephalin spiked with substance P as an internal standard, respectively. Both treated and bare copper surfaces were cut to 90, 60, and 30° angles. Calibration curves were constructed for both peptides on a superhydrophobic surface using covalently bonded trichloro(1H, 1H, 2H, 2H-perflourooctyl)silane-treated copper, and bare copper surface. The highest sensitivity for all peptides was observed using a 30 or 60° tip with the silane-treated copper. Limits of detection and quantitation for the 60° silane-treated surface for bradykinin were 6.01 × 10−3 μM and 2.00 × 10−2 μM respectively, with a R2 of 0.9959. Limits of detection and quantitation for the 30° silane-treated surface for leucine-enkephalin were 3.28 × 10−2 μM and 1.09 × 10−1 μM respectively, with a R2 of 0.9993. Image 1 • Copper surfaces were used as spray initiators similar to paper spray ionization. • Surfaces are reusable, have fixed geometry, and can be functionalized, and require minimal solvent to initiate a spray event. • Metalspray ionization was used to test sensitivity between bare copper and modified copper surfaces. • Copper was functionalized with trichloro(1 H , 1 H , 2 H , 2 H -perflourooctyl)silane to create a superhydrophobic surface. • Superhydrophobic surface displayed greater sensitivity and lower limits of quantitation compared to bare copper surface. [ABSTRACT FROM AUTHOR]

Summary Preeclampsia is the most frequent pregnancy-related complication worldwide with no cure. While a number of molecular features have emerged, the underlying causal mechanisms behind the disorder remain obscure. Here, we find that increased complex formation between angiotensin II AT1 and bradykinin B2, two G protein-coupled receptors with opposing effects on blood vessel constriction, triggers symptoms of preeclampsia in pregnant mice. Aberrant heteromerization of AT1-B2 led to exaggerated calcium signaling and high vascular smooth muscle mechanosensitivity, which could explain the onset of preeclampsia symptoms at late-stage pregnancy as mechanical forces increase with fetal mass. AT1-B2 receptor aggregation was inhibited by beta-arrestin-mediated downregulation. Importantly, symptoms of preeclampsia were prevented by transgenic ARRB1 expression or a small-molecule drug. Because AT1-B2 heteromerization was found to occur in human placental biopsies from pregnancies complicated by preeclampsia, specifically targeting AT1-B2 heteromerization and its downstream consequences represents a promising therapeutic approach. Graphical Abstract Highlights • The beta-arrestin-biased agonist, TRV027, targets AT1-B2 and prevents preeclampsia • AT1-B2 enhances the vascular sensitivity to angiotensin II and mechanical stimulation • Increased vascular AT1-B2 in pregnant mice is a sufficient cause for preeclampsia • Transgenic ARRB1 counteracts preeclampsia symptoms by downregulation of AT1-B2 This paper provides a mechanistic understanding of the causes of preeclampsia and uses the newly gained insights to explore treatment for the condition. [ABSTRACT FROM AUTHOR]

While the role of the brain kallikrein-kinin system in the development of various pathological processes, such as oedema formation following brain injury or induction of central hypertonia has generated major interest, the possible role of this system in nociceptive processing has received little attention. In their present paper, Mortari et al. (2007) show that bradykinin B2 receptor activation in the brain by the bradykinin analogue, Thr6-bradykinin, isolated from the venom of the social wasp, Polybia occidentalis potently reduces acute, noxious heat-evoked reflex responses in naive rats. The unknown underlying mechanism of this powerful antinociceptive effect reminds us that the supraspinal antinociceptive system is still a “black box” in many aspects and awaits thorough investigation.British Journal of Pharmacology (2007) 151, 721–722; doi:10.1038/sj.bjp.0707274; published online 29 May 2007 [ABSTRACT FROM AUTHOR]

A conference paper on the role of extracellular products of the mastitis-inducing pathogens, Escherichia coli (EC), and Staphylococcus aureus (SA) in the activation of bovine milk kallikreins is presented. The study indicated that the presence in milk of the pathogens is associated with elevated bradykinin (BK) levels. It showed that both EC and SA directly activate BK formation in milk by activating synthetic tissue- and plasma-kallikreins-like activity in the milk.

A conference paper about the role of gap junctions in the bradykinin-induced relaxation of the bovine pulmonary supernumerary arteries is presented. It discusses on how the assessment was made with the use of fresh bovine lungs including the different phases the tissue underwent. Further, it revealed that gap junctions does not contribute to the bradykinin-induced relaxation of bovine supernumerary arteries instead it involved in the mediation with nitric acid.

A conference paper about the non-cholinergic component of the bronchoconstrictor response to bradykinin (BK) is presented. It investigates the involvement of leukotrienes, tachykinins and the peptidases, angiotensin converting enzyme and neutral endopeptidase. It shows that the bronchoconstrictor response to BK is not mediated by leukotrienes or tachykinins.

A conference paper about the selectivity of the ascorbate blockade in the ciliary vascular bed and the occurrence of the blockade in the porcine left anterior descending coronary artery is presented. It reveals that bradykinin induces concentration-dependent and endothelium-derived hyperpolarizing factor (EDHF)-mediated vasodilatation. It concludes that ascorbate-induced blockade of EDHF-mediated vasodilatation in the bovine ciliary circulation appears to be selective.

A conference paper about the ability of large pulmonary arteries to utilize an endothelium-derived hyperpolarizing factor (EDHF) after removing nitric oxide or inhibiting guanylyl cyclase is presented. It discusses the effect of potassium channel blockers on the concentration response curve for bradykinin-induced relaxation. It concludes that bradykinin induces relaxation in this study.

There is now abundant evidence that treatment with angiotensin-converting enzyme inhibitors (ACE-I) ameliorates the progression of chronic renal disease. Attention has therefore focused on the role of the renin angiotensin-aldosterone (RAA) system in mediating the development of progressive glomerulosclerosis and angiotensin II (Ang II) has been implicated in several processes thought to be important in the pathogenesis of this entity. Conversely, ACE is also known to catalyse the breakdown of bradykinin. Thus, ACE-I treatment results in elevated bradykinin levels which may cause selective efferent arteriolar dilatation, suggesting an alternative explanation for the beneficial effects of this class of drugs in chronic renal disease. The development of specific angiotensin type 1 receptor antagonists (AT[sub1]RA) has provided a means of testing the relative importance of these two mechanisms. In addition, AT[sub1]RAs differ from ACE-I in their effect on the RAA system in other aspects which may represent therapeutic advantages. This paper reviews studies which have compared ACE-I and AT[sub1]RAs in several rat models of chronic renal disease. Most have found similar beneficial effects including amelioration of proteinuria and glomerulosclerosis, which suggests that the effects of ACE-I are due to a reduction in Ang II activity and not due to increased levels of bradykinin. One long-term study has suggested greater renal protection with candesartan than with enalapril. However, conclusions as regards the relative efficacy of these two groups of agents in ameliorating the progression of chronic renal disease await the results of further long-term studies. [ABSTRACT FROM AUTHOR]