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Kinin receptors B1 and B2 are involved in migration and invasion in gastric, glioma, and cervical cancer cells, among others. However, the role of kinin receptors in breast cancer cells has been poorly studied. We aimed to reveal the impact of B1 and B2 receptors on migration and invasion in breast cancer cells and demonstrate their capacity to modulate in vivo tumor growth. MDA-MB-231, MCF-7, and T47D cells treated with Lys-des[Arg9]bradykinin (LDBK) or bradykinin (BK) were used to evaluate migration and invasion. Des-[Arg9]-Leu8-BK and HOE-140 were used as antagonists for the B1 and B2 receptors. MDA-MB-231 cells incubated or not with antagonists were subcutaneously inoculated in BALBc NOD/SCID mice to evaluate tumor growth. LDBK and BK treatment significantly increased migration and invasion in breast cancer cells, effects that were negated when antagonists were used. The use of antagonists in vivo inhibited tumor growth. Moreover, the migration and invasion induced by kinins in breast cancer cells were inhibited when focal adhesion kinase (FAK) and Src inhibitors were used. The novelty revealed in our work is that B1 and B2 receptors activated by LDBK and BK induce migration and invasion in breast cancer cells via a mechanism that involves the FAK–Src signaling pathway, and the antagonism of both receptors in vivo impairs breast tumor growth. [ABSTRACT FROM AUTHOR]

Abstract Background The kallikrein-kinin system is a key regulatory cascade involved in blood pressure maintenance, hemostasis, inflammation and renal function. Currently, approved drugs remain limited to the rare disease hereditary angioedema. However, growing interest in this system is indicated by an increasing number of promising drug candidates for further indications. Methods To provide an overview of current drug development, a two-stage literature search was conducted between March and December 2023 to identify drug candidates with targets in the kallikrein-kinin system. First, drug candidates were identified using PubMed and Clinicaltrials.gov. Second, the latest publications/results for these compounds were searched in PubMed, Clinicaltrials.gov and Google Scholar. The findings were categorized by target, stage of development, and intended indication. Results The search identified 68 drugs, of which 10 are approved, 25 are in clinical development, and 33 in preclinical development. The three most studied indications included diabetic retinopathy, thromboprophylaxis and hereditary angioedema. The latter is still an indication for most of the drug candidates close to regulatory approval (3 out of 4). For the emerging indications, promising new drug candidates in clinical development are ixodes ricinus-contact phase inhibitor for thromboprophylaxis and RZ402 and THR-149 for the treatment of diabetic macular edema (all phase 2). Conclusion The therapeutic impact of targeting the kallikrein-kinin system is no longer limited to the treatment of hereditary angioedema. Ongoing research on other diseases demonstrates the potential of therapeutic interventions targeting the kallikrein-kinin system and will provide further treatment options for patients in the future.

Background: The kallikrein-kinin system is a key regulatory cascade involved in blood pressure maintenance, hemostasis, inflammation and renal function. Currently, approved drugs remain limited to the rare disease hereditary angioedema. However, growing interest in this system is indicated by an increasing number of promising drug candidates for further indications. Methods: To provide an overview of current drug development, a two-stage literature search was conducted between March and December 2023 to identify drug candidates with targets in the kallikrein-kinin system. First, drug candidates were identified using PubMed and Clinicaltrials.gov. Second, the latest publications/results for these compounds were searched in PubMed, Clinicaltrials.gov and Google Scholar. The findings were categorized by target, stage of development, and intended indication. Results: The search identified 68 drugs, of which 10 are approved, 25 are in clinical development, and 33 in preclinical development. The three most studied indications included diabetic retinopathy, thromboprophylaxis and hereditary angioedema. The latter is still an indication for most of the drug candidates close to regulatory approval (3 out of 4). For the emerging indications, promising new drug candidates in clinical development are ixodes ricinus-contact phase inhibitor for thromboprophylaxis and RZ402 and THR-149 for the treatment of diabetic macular edema (all phase 2). Conclusion: The therapeutic impact of targeting the kallikrein-kinin system is no longer limited to the treatment of hereditary angioedema. Ongoing research on other diseases demonstrates the potential of therapeutic interventions targeting the kallikrein-kinin system and will provide further treatment options for patients in the future. [ABSTRACT FROM AUTHOR]

The kallikrein–kinin system consists of the two kininogen substrates present in the blood plasma, and two serine proteases: the plasma and tissue kallikreins. The action of the latter on kininogens produces small peptides, the kinins, short-lived, but endowed by powerful pharmacologic actions on blood vessels and other tissues. Many recent and exciting therapeutic developments in the field are briefly summarized. Notably, various novel strategies are being clinically developed to inhibit the formation of bradykinin or block its receptors in the management of hereditary angioedema. The interventions include orally bioavailable drugs, biotechnological proteins, and gene therapy. These approaches are currently explored in a variety of other inflammatory and thrombotic disorders. Harnessing controlled kinin formation is also of potential therapeutic interest, as shown by the clinical development of recombinant tissue kallikrein for ischemic stroke and renal disease. The biomarkers of kinin-mediated disorders, frequently implicating edemas, include the consumption of kininogen(s), plasma kallikrein activity, and the detection of circulating kinin metabolites such as fragments BK1–5 and BK2–9. Novel opportunities to clinically apply the underexploited drugs of the kallikrein–kinin system are briefly reviewed. This personal perspective is offered by an observer of and a participant in drug characterization throughout the last four decades.

The kallikrein–kinin system consists of the two kininogen substrates present in the blood plasma, and two serine proteases: the plasma and tissue kallikreins. The action of the latter on kininogens produces small peptides, the kinins, short-lived, but endowed by powerful pharmacologic actions on blood vessels and other tissues. Many recent and exciting therapeutic developments in the field are briefly summarized. Notably, various novel strategies are being clinically developed to inhibit the formation of bradykinin or block its receptors in the management of hereditary angioedema. The interventions include orally bioavailable drugs, biotechnological proteins, and gene therapy. These approaches are currently explored in a variety of other inflammatory and thrombotic disorders. Harnessing controlled kinin formation is also of potential therapeutic interest, as shown by the clinical development of recombinant tissue kallikrein for ischemic stroke and renal disease. The biomarkers of kinin-mediated disorders, frequently implicating edemas, include the consumption of kininogen(s), plasma kallikrein activity, and the detection of circulating kinin metabolites such as fragments BK1–5 and BK2–9. Novel opportunities to clinically apply the underexploited drugs of the kallikrein–kinin system are briefly reviewed. This personal perspective is offered by an observer of and a participant in drug characterization throughout the last four decades. [ABSTRACT FROM AUTHOR]

Abstract Background Tibial fracture is associated with inflammatory reaction leading to severe pain syndrome. Bradykinin receptor activation is involved in inflammatory reactions, but has never been investigated in fracture pain. Methods This study aims at defining the role of B1 and B2-kinin receptors (B1R and B2R) in a closed tibial fracture pain model by using knockout mice for B1R (B1KO) or B2R (B2KO) and wild-type (WT) mice treated with antagonists for B1R (SSR 240612 and R954) and B2R (HOE140) or vehicle. A cyclooxygenase (COX) inhibitor (ketoprofen) and an antagonist (SB366791) of Transient Receptor Potential Vaniloid1 (TRPV1) were also investigated since these pathways are associated with BK-induced pain in other models. The impact on mechanical and thermal hyperalgesia and locomotion was assessed by behavior tests. Gene expression of B1R and B2R and spinal cord expression of c-Fos were measured by RT-PCR and immunohistochemistry, respectively. Results B1KO and B2KO mice demonstrated a reduction in post-fracture pain sensitivity compared to WT mice that was associated with decreased c-Fos expression in the ipsilateral spinal dorsal horn in B2KO. B1R and B2R mRNA and protein levels were markedly enhanced at the fracture site. B1R and B2R antagonists and inhibition of COX and TRPV1 pathways reduced pain in WT. However, the analgesic effect of the COX-1/COX-2 inhibitor disappeared in B1KO and B2KO. In contrast, the analgesic effect of the TRPV1 antagonist persisted after gene deletion of either receptor. Conclusions It is suggested that B1R and B2R activation contributes significantly to tibial fracture pain through COX. Hence, B1R and B2R antagonists appear potential therapeutic agents to manage post fracture pain.

We here report the discovery and early characterization of Compound 3, a representative of a novel class of small molecule bradykinin (BK) B2 receptor antagonists, and its superior profile to the prior art B2 receptor antagonists Compound 1 and Compound 2. Compound 3, Compound 2, and Compound 1 are highly potent antagonists of the human recombinant B2 receptor (Kb values 0.24, 0.95, and 1.24 nM, respectively, calcium mobilization assay). Compound 3 is more potent than the prior art compounds and icatibant in this assay (Kb icatibant 2.81 nM). The compounds also potently inhibit BK-induced contraction of endogenous B2 receptors in a human isolated umbilical vein bioassay. The potencies of Compound 3, Compound 2, Compound 1, and icatibant are (pA2 values) 9.67, 9.02, 8.58, and 8.06 (i.e. 0.21, 0.95, 2.63, and 8.71 nM), respectively. Compound 3 and Compound 2 were further characterized. They inhibit BK-induced c-Fos signaling and internalization of recombinant human B2 receptors in HEK293 cells, and do not antagonize the venous effects mediated by other G protein-coupled receptors in the umbilical vein model, including the bradykinin B1 receptor. Antagonist potency of Compound 3 at cloned cynomolgus monkey, dog, rat, and mouse B2 receptors revealed species selectivity, with a high antagonist potency for human and monkey B2 receptors, but several hundred-fold lower potency for the other B2 receptors. The in vitro off-target profile of Compound 3 demonstrates a high degree of selectivity over a wide range of molecular targets, including the bradykinin B1 receptor. Compound 3 showed a lower intrinsic clearance in the microsomal stability assay than the prior art compounds. With an efflux ratio of 1.0 in the Caco-2 permeability assay Compound 3 is predicted to be not a substrate of efflux pumps. In conclusion, we discovered a novel chemical class of highly selective and very potent B2 receptor antagonists, as exemplified by Compound 3. The compound showed excellent absorption in the Caco-2 assay, predictive of good oral bioavailability, and favourable metabolic stability in liver microsomes. Compound 3 has provided a significant stepping stone towards the discovery of the orally bioavailable B2 antagonist PHA-022121, currently in phase 1 clinical development.

We here report the discovery and early characterization of Compound 3, a representative of a novel class of small molecule bradykinin (BK) B2 receptor antagonists, and its superior profile to the prior art B2 receptor antagonists Compound 1 and Compound 2. Compound 3, Compound 2, and Compound 1 are highly potent antagonists of the human recombinant B2 receptor (Kb values 0.24, 0.95, and 1.24 nM, respectively, calcium mobilization assay). Compound 3 is more potent than the prior art compounds and icatibant in this assay (Kb icatibant 2.81 nM). The compounds also potently inhibit BK-induced contraction of endogenous B2 receptors in a human isolated umbilical vein bioassay. The potencies of Compound 3, Compound 2, Compound 1, and icatibant are (pA2 values) 9.67, 9.02, 8.58, and 8.06 (i.e. 0.21, 0.95, 2.63, and 8.71 nM), respectively. Compound 3 and Compound 2 were further characterized. They inhibit BK-induced c-Fos signaling and internalization of recombinant human B2 receptors in HEK293 cells, and do not antagonize the venous effects mediated by other G protein-coupled receptors in the umbilical vein model, including the bradykinin B1 receptor. Antagonist potency of Compound 3 at cloned cynomolgus monkey, dog, rat, and mouse B2 receptors revealed species selectivity, with a high antagonist potency for human and monkey B2 receptors, but several hundred-fold lower potency for the other B2 receptors. The in vitro off-target profile of Compound 3 demonstrates a high degree of selectivity over a wide range of molecular targets, including the bradykinin B1 receptor. Compound 3 showed a lower intrinsic clearance in the microsomal stability assay than the prior art compounds. With an efflux ratio of 1.0 in the Caco-2 permeability assay Compound 3 is predicted to be not a substrate of efflux pumps. In conclusion, we discovered a novel chemical class of highly selective and very potent B2 receptor antagonists, as exemplified by Compound 3. The compound showed excellent absorption in the Caco-2 assay, predictive of good oral bioavailability, and favourable metabolic stability in liver microsomes. Compound 3 has provided a significant stepping stone towards the discovery of the orally bioavailable B2 antagonist PHA-022121, currently in phase 1 clinical development. [ABSTRACT FROM AUTHOR]

Bradykinin (BK) has various physiological and pathological roles. Medicinal chemistry efforts targeted toward the widely expressed BK B2 receptor (B2R), a G-protein-coupled receptor, were primarily aimed at developing antagonists. The only B2R antagonist in clinical use is the peptide icatibant, approved to abort attacks of hereditary angioedema. However, the anti-inflammatory applications of B2R antagonists are potentially wider. Furthermore, the B2R antagonists notoriously exhibit species-specific pharmacological profiles. Classical smooth muscle contractility assays are exploited over a time scale of several hours and support determining potency, competitiveness, residual agonist activity, specificity, and reversibility of pharmacological agents. The contractility assay based on the isolated human umbilical vein, expressing B2R at physiological density, was introduced when investigating the first non-peptide B2R antagonist (WIN 64338). Small ligand molecules characterized using the assay include the exquisitely potent competitive antagonist, Pharvaris Compound 3 or the partial agonist Fujisawa Compound 47a. The umbilical vein assay is also useful to verify pharmacologic properties of special peptide B2R ligands, such as the carboxypeptidase-activated latent agonists and fluorescent probes. Furthermore, the proposed agonist effect of tissue kallikrein on the B2R has been disproved using the vein. This assay stands in between cellular and molecular pharmacology and in vivo studies.

Background: Alzheimer’s disease is mainly characterized by remarkable neurodegeneration in brain areas related to memory formation. This progressive neurodegeneration causes cognitive impairment, changes in behavior, functional disability, and even death. Our group has demonstrated changes in the kallikrein–kinin system (KKS) in Alzheimer’s disease (AD) experimental models, but there is a lack of evidence about the role of the KKS in Alzheimer’s disease. Aim: In order to answer this question, we evaluated the potential of the kinin B2 receptors (BKB2R) to modify AD characteristics, particularly memory impairment, neurodegeneration, and Aβ peptide deposition. Methods: To assess the effects of B2, we used transgenic Alzheimer’s disease mice treated with B2 receptor (B2R) agonists and antagonists, and performed behavioral and biochemical tests. In addition, we performed organotypic hippocampal culture of wild-type (WT) and transgenic (TG) animals, where the density of cytokines, neurotrophin BDNF, activated astrocyte marker S100B, and cell death were analyzed after treatments. Results: Treatment with the B2R agonist preserved the spatial memory of transgenic mice and decreased amyloid plaque deposition. In organotypic hippocampal culture, treatment with B2R agonist decreased cell death, neuroinflammation, and S100B levels, and increased BDNF release. Conclusions: Our results indicate that the kallikrein–kinin system plays a beneficial role in Alzheimer’s disease through B2R activation. The use of B2R agonists could, therefore, be a possible therapeutic option for patients diagnosed with Alzheimer’s disease.

Abstract Several G protein-coupled receptors are present in lipid rafts. We have shown that most of the P2Y 2 receptor (P2Y 2 R) protein is fractionated into lipid rafts in COS 7 cells. In the same cells, about 25–30% of the bradykinin B2 receptor (B2R) protein is also fractionated into lipid rafts. When both P2Y 2 R and B2R are co-expressed, the distribution of P2Y 2 R remained unchanged, but more B2R shifted into the raft fraction. This indicates that the interaction between both receptors recruited B2R into the lipid rafts. After 15 min of UTP stimulation, both receptors almost completely disappeared from the cell surface by endocytosis as observed with a confocal fluorescence microscope. Furthermore, with bradykinin stimulation for 15 min, portions of both receptors disappeared from the cell surface and were endocytosed. As we reported previously with both CHO-K1 cells and HEK 293 cells, continuous stimulation of COS7 cells with GT1b and CSC resulted in the disappearance of both P2Y 2 R and B2R from the cell membrane surface. Thus, both P2Y 2 R and B2R migrate into membrane rafts and are endocytosed in parallel with signal crosstalk, clearly indicating that both closely interact on membrane rafts. The P2Y 2 R N -glycosylation deficient mutant does not migrate to the cell surface. It remains predominantly in the endoplasmic reticulum and is fractionated into raft fractions. In the presence of this glycosylation mutant, most of B2R remains in the endoplasmic reticulum, and is fractionated into the raft fraction. These findings demonstrate that in the membrane rafts of the endoplasmic reticulum, both receptors are already closely associated, and B2R shifts into the rafts by affinity with P2Y 2 R. Highlights • P2Y 2 R recruits bradykinin B2R to lipid rafts. • B2R does not affect lipid raft distribution of P2Y 2 R. • Signal crosstalk between P2Y 2 R and B2R occurs in lipid rafts. • Association of P2Y 2 R with both lipid rafts and B2R occurs in the ER. [ABSTRACT FROM AUTHOR]

It is known that bradykinin (BK) B2 receptor (B2R) is expressed in the collecting duct (CD) cells of the newborn rat kidney, but little is known about its role during early postnatal life. Therefore, we hypothesize that BK could participate in the mechanisms that mediate CD formation during the postnatal renal development. Performing primary cultures, combined with biochemical, immunocytochemical, and time‐lapse analysis, we studied the role of BK in CD cell behavior isolated from renal papilla of neonatal rats. A reverse relationship was observed between B2R expression and the degree of CD epithelial cell sheet maturation. BK stimulation induced CD cell association upon B2R activation. The lack of B2R expression in cells showing mature adherens junctions suggested that BK is mostly involved in early adhesive events, thus favoring the initial formation of CD during development. Time‐lapse analysis revealed that BK induced a high protrusive activity of CD cells, denoted by ruffle formation and lamellipodia extension. PI3K was involved in the BK‐induced CD cell‐cell association and the acquisition of the migratory phenotype since, when inhibited, membrane ruffles, and filopodia between cells diminished. Results indicate that the actions of BK mediated by PI3K activation were due to the downstream Akt and Rac pathways. This study, performed with CD cells that were not genetically manipulated, provides new experimental evidence supporting a novel role of BK in rat renal CD organization. As B2R blockade results in abnormal tubular differentiation, our results contribute to better understanding the etiology of human congenital renal malformation and diseases. [ABSTRACT FROM AUTHOR]

Bradykinin-related peptides (BRPs) are one of the most extensively studied frog secretions-derived peptide families identified from many amphibian species. The diverse primary structures of BRPs have been proven essential for providing valuable information in understanding basic mechanisms associated with drug modification. Here, we isolated, identified and characterized a dodeca-BRP (RAP-L1, T6-BK), with primary structure RAPLPPGFTPFR, from the skin secretions of Chinese large odorous frogs, Odorrana livida. This novel peptide exhibited a dose-dependent contractile property on rat bladder and rat ileum, and increased the contraction frequency on rat uterus ex vivo smooth muscle preparations; it also showed vasorelaxant activity on rat tail artery smooth muscle. In addition, the analogue RAP-L1, T6, L8-BK completely abolished these effects on selected rat smooth muscle tissues, whilst it showed inhibition effect on bradykinin-induced rat tail artery relaxation. By using canonical antagonist for bradykinin B1 or B2 type receptors, we found that RAP-L1, T6-BK -induced relaxation of the arterial smooth muscle was very likely to be modulated by B2 receptors. The analogue RAP-L1, T6, L8-BK further enhanced the bradykinin inhibitory activity only under the condition of co-administration with HOE140 on rat tail artery, suggesting a synergistic inhibition mechanism by which targeting B2 type receptors. [ABSTRACT FROM AUTHOR]

Bradykinin B2 receptor (B2R) and angiotensin-(1-7) Mas receptor (MasR)-mediated effects are physiologically interconnected. The molecular basis for such cross talk is unknown. It is hypothesized that the cross talk occurs at the receptor level. We investigated B2R-MasR heteromerization and the functional consequences of such interaction. B2R fused to the cyan fluorescent protein and MasR fused to the yellow fluorescent protein were transiently coexpressed in human embryonic kidney293T cells. Fluorescence resonance energy transfer analysis showed that B2R and MasR formed a constitutive heteromer, which was not modified by their agonists. B2R or MasR antagonists decreased fluorescence resonance energy transfer efficiency, suggesting that the antagonist promoted heteromer dissociation. B2R-MasR heteromerization induced an 8-fold increase in the MasR ligand-binding affinity. On agonist stimulation, the heteromer was internalized into early endosomes with a slower sequestration rate from the plasma membrane, compared with single receptors. B2R-MasR heteromerization induced a greater increase in arachidonic acid release and extracellular signal-regulated kinase phosphorylation after angiotensin-(1-7) stimulation, and this effect was blocked by the B2R antagonist. Concerning serine/threonine kinase Akt activity, a significant bradykinin-promoted activation was detected in B2R-MasR but not in B2R-expressing cells. Angiotensin-(1-7) and bradykinin elicited antiproliferative effects only in cells expressing B2R-MasR heteromers, but not in cells expressing each receptor alone. Proximity ligation assay confirmed B2R-MasR interaction in human glomerular endothelial cells supporting the interaction between both receptors in vivo. Our findings provide an explanation for the cross talk between bradykinin B2R and angiotensin-(1-7) MasR-mediated effects. B2R-MasR heteromerization induces functional changes in the receptor that may lead to long-lasting protective properties. [ABSTRACT FROM AUTHOR]

The centrally acting antitussive opiate derivative, noscapine, has been claimed to be a non-competitive bradykinin B 2 receptor antagonist. Raloxifene, a selective estrogen receptor modulator, was predicted to bind the bradykinin B 2 receptor and to exert a partial agonist activity. These intriguing claims suggest that new molecular scaffolds ("chemotypes") may be identified for small molecule ligands of kinin receptors and that some off-target effects of noscapine or raloxifene may be mediated by bradykinin B 2 receptors. An established contractile bioassay for ligands of the bradykinin B 2 receptor, the isolated human umbilical vein, was exploited to characterize the inhibitory effect of noscapine and raloxifene on the B 2 receptor-mediated contractile response to bradykinin. Observed effects were compared with those of the peptide antagonist icatibant, a potent, selective and competitive B 2 receptor antagonist. Our results indicate that neither noscapine (2.5 µM) nor raloxifene (20 µM) behave as B 2 receptor antagonists in concentrations that vastly exceeded an effective concentration of the control antagonist, icatibant; further, none of these drugs had direct contractile effects. It is suggested that the previously reported B 2 receptor inhibitory effect of noscapine, a putative sigma-receptor agonist, might result from an indirect physiological antagonism, while raloxifene did not appear to have any significant affinity for the B 2 receptors. [ABSTRACT FROM AUTHOR]

It is well known that the responses to vasoactive kinin peptides are mediated through the activation of two receptors termed bradykinin receptor B1 (B1R) and B2 (B2R). The physiologically prominent B2R subtype has certainly been the subject of more intensive efforts in structure-function studies and physiological investigations. However, the B1R activated by a class of kinin metabolites has emerged as an important subject of investigation within the study of the kallikrein-kinin system (KKS). Its inducible character under stress and tissue injury is therefore a field of major interest. Although the KKS has been associated with cardiovascular regulation since its discovery at the beginning of the last century, less is known about the B1R and B2R regulation in cardiovascular diseases like hypertension, myocardial infarction (MI) and their complications. This mini-review will summarize our findings on B1R and B2R regulation after induction of MI using a rat model. We will develop the hypothesis that differences in the expression of these receptors may be associated with a dual pathway of the KKS in the complex mechanisms of myocardial remodeling.

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Purpose: Radiation-induced heart disease (RIHD) is a delayed effect of radiotherapy for cancers of the chest, such as breast, esophageal, and lung. Kinins are small peptides with cardioprotective properties. We previously used a rat model that lacks the precursor kininogen to demonstrate that kinins are involved in RIHD. Here, we examined the role of the kinin B2 receptor (B2R) in early radiation-induced signaling in the heart. Materials and methods: Male Brown Norway rats received the B2R-selective antagonist HOE-140 (icatibant) via osmotic minipump from 5 days before until 4 weeks after 21 Gy local heart irradiation. At 4 weeks, signaling events were measured in left ventricular homogenates and nuclear extracts using western blotting and real-time polymerase chain reaction. Numbers of CD68-positive (monocytes/macrophages), CD2-positive (T-lymphocytes), and mast cells were measured using immunohistochemistry. Results: Radiation-induced c-Jun phosphorylation and nuclear translocation were enhanced by HOE-140. HOE-140 did not modify endothelial nitric oxide synthase (eNOS) phosphorylation or alter numbers of CD2-positive or mast cells, but enhanced CD68-positive cell counts in irradiated hearts. Conclusions: B2R signaling may regulate monocyte/macrophage infiltration and c-Jun signals in the irradiated heart. Although eNOS is a main target for kinins, the B2R may not regulate eNOS phosphorylation in response to radiation. [ABSTRACT FROM AUTHOR]

Background and purpose Aβ-induced neuronal toxicity and memory loss is thought to be dependent on neuroinflammation, an important event in Alzheimer's disease (AD). Previously, we demonstrated that the blockage of the kinin B 2 receptor (B 2 R) protects against the memory deficits induced by amyloid β (Aβ) peptide in mice. In this study, we aimed to investigate the role of B 2 R on Aβ-induced neuroinflammation in mice and the beneficial effects of B 2 R blockage in synapses alterations. Experimental approach The selective kinin B 2 R antagonist HOE 140 (50 pmol/site) was given by intracerebroventricular (i.c.v.) route to male Swiss mice 2 h prior the i.c.v. injection of Aβ 1–40 (400 pmol/site) peptide. Animals were sacrificed, at specific time points after Aβ 1–40 injection (6 h, 1 day or 8 days), and the brain was collected in order to perform immunohistochemical analysis. Different groups of animals were submitted to behavioral cognition tests on day 14 after Aβ 1–40 administration. Key results In this study, we report that the pre-treatment with the selective kinin B 2 R antagonist HOE 140 significantly inhibited Aβ-induced neuroinflammation in mice. B 2 R antagonism reduced microglial activation and the levels of pro-inflammatory proteins, including COX-2, iNOS and nNOS. Notably, these phenomena were accompanied by an inhibition of MAPKs (JNK and p38) and transcription factors (c-Jun and p65/NF-κB) activation. Finally, the anti-inflammatory effects of B 2 R antagonism provided significant protection against Aβ 1–40 -induced synaptic loss and cognitive impairment in mice. Conclusions and implications Collectively, these results suggest that B 2 R activation may play a critical role in Aβ-induced neuroinflammation, one of the most important contributors to AD progression, and its blockage can provide synapses protection. [ABSTRACT FROM AUTHOR]