B2 Receptor Antagonist Research Articles

Surface megalin expression is a target to the inhibitory effect of bradykinin on the renal albumin endocytosis

Megalin-mediated albumin endocytosis plays a critical role in albumin reabsorption in proximal tubule (PT) epithelial cells (PTECs). Some studies have pointed out the modulatory effect of bradykinin (BK) on urinary protein excretion, but its role in PT protein endocytosis has not yet been determined. Here, we studied the possible correlation between BK and albumin endocytosis in PT. Using LLC-PK1 cells, a model of PTECs, we showed that BK specifically inhibited megalin-mediated albumin endocytosis. This inhibitory effect of BK was mediated by B2 receptor (B2R) because it was abolished by HOE140, an antagonist of B2R, but it was not affected by Lys-des-Arg9-BK, an antagonist of B1. BK induced the stall of megalin in EEA1+ endosomes, but not in LAMP1+ lysosomes, leading to a decrease in surface megalin expression. In addition, we showed that BK, through B2R, activated calphostin C-sensitive protein kinase C, which mediated its effect on the surface megalin expression and albumin endocytosis. These results reveal an important modulatory mechanism of PT albumin endocytosis by BK, which opens new possibilities to understanding the effect of BK on urinary albumin excretion.

Bradykinin receptors in GtoPdb v.2021.3

Bradykinin (or kinin) receptors (nomenclature as agreed by the NC-IUPHAR subcommittee on Bradykinin (kinin) Receptors [91]) are activated by the endogenous peptides bradykinin (BK), [des-Arg9]bradykinin, Lys-BK (kallidin), [des-Arg10]kallidin, [Phospho-Ser6]-Bradykinin, T-kinin (Ile-Ser-BK), [Hyp3]bradykinin and Lys-[Hyp3]-bradykinin. Variation in pharmacology and activity of B1 and B2 receptor antagonists at species orthologs has been documented. icatibant (Hoe140, Firazir) is approved in North America and Europe for the treatment of acute attacks of hereditary angioedema.

Recognition and Management of Hereditary Angioedema: Best Practices for Dermatologists.

ObjectiveThe goal of this article is to discuss the importance of differentiating hereditary angioedema (HAE) from other types of angioedema, describe advances in HAE management, especially long-term prophylaxis (LTP), and offer practical recommendations for dermatologists.CommentaryWhile HAE is rare, dermatologists are likely to encounter patients with this condition at some point over the course of their clinical practice due to the fact that HAE episodes typically involve subcutaneous swelling and sometimes erythema marginatum. HAE is characterized by recurrent episodes of painful and/or disabling bradykinin-mediated angioedema. Unfortunately, HAE is commonly mistaken for other conditions such as allergic and other mast cell-mediated angioedema, but has very different treatment requirements. Delayed diagnosis of HAE can result in years of avoidable debilitating symptoms, inappropriate treatment, potentially unnecessary invasive intervention, and reduced quality of life, and can be life threatening. Thus, timely identification of HAE is essential to ensure appropriate clinical management. Patients with HAE have either deficiency or dysfunction of the C1 inhibitor (C1INH) protein that inhibits proteases in the contact, complement, and fibrinolytic systems. Pathway-specific HAE treatments include C1INH replacement, kallikrein inhibitors, and bradykinin receptor antagonists. Treatment options for managing acute attacks include C1INH replacement (plasma-derived or recombinant formulations), icatibant (kallikrein inhibitor), and ecallantide (bradykinin B2 receptor antagonist). In the past 5 years, several new options for LTP have been approved, including a subcutaneous plasma-derived C1INH formulation and two kallikrein inhibitors (lanadelumab; berotralstat). Optimal management of HAE entails the creation of a comprehensive management plan that addresses both acute and long-term patient needs and includes input from an HAE expert and the patient/caregivers.

MO067DELETION AND BLOCKAGE OF KININ B1 RECEPTOR EXACERBATES CISPLATIN-INDUCED CKD

Abstract Background and Aims Kinins plays a major role in immune response, where kinin B2 receptor is constitutively expressed and kinin B1 receptor is induced under inflammatory stimuli. Kinin B1 receptor deletion and blockage has been shown to have beneficial effects in some models of renal diseases. Multiple acute renal insults, even if followed by renal recovery, is a risk factor for the future development of chronic kidney disease (CKD) and end-stage renal disease (ESRD). Our main objective was to determine the importance of kinin B1 receptor in tubulointerstitial fibrosis induced by ongoing cisplatin treatment. Method Male C57/Bl6 mice were divided in 3 groups, vehicle, cisplatin, cisplatin + R715 (kinin B1 receptor antagonist). Animals has been treated with multiple doses of cisplatin (7mg/kg i.p) once a week during 4 weeks and R715 (0.8mg/kg i.p) 48, 24 and 1 hour prior to cisplatin injections. We also used B1KO mice (C57Bl6 background) and WT mice (littermates). Mice were euthanized after 30 days of last cisplatin injection. Renal parameters, histology, real time PCR were performed to investigate renal injury, inflammation and fibrosis. Results Cisplatin treatment increases most of renal parameters, renal injury and fibrosis markers. Deletion of B1 receptor exacerbates significantly creatinine (WT CIS 0,60+0,03 B1KO 0,76+0,01 mg/dL), urea (WT CIS 111,8+5,638 B1KO CIS 240,8+28,60 mg/dL), and protein excretion (WT CIS 0,0058+0,0011 B1KO CIS 0,0121+0,0007 mg/24h). Association of cisplatin with R715 increased creatinine levels (veh 0,43+0,03 cis+R715 0,64+0,04 mg/dL), exacerbates urea (cis 95,51 + 3,926 cis+R715 158,9+14,40 mg/dL) and protein excretion (cis 0,012+0,002 cis+R715 0,018+0,003 mg/24h). Renal injury markers such as KIM-1 and TNF-a showed no significant differences. NGAL expression exacerbates (cis 2,53+0,44 cis+R715 5,66+1,34) and tubular injury score (cis 0,130+0,021 cis+R715 0,191+0,020) is higher in cisplatin+R715 group. Fibrosis markers a-SMA (cis 2,56+0,43 cis+R715 4,67+0,99), Col4 (cis 2,57+0,39 cis+R715 5,14+1,01) and Vimentin (2,69+0,31 cis+R715 4,62+0,98) were exacerbated in cisplatin treatment associated with R715. Picrosirius red staining were used to asses tubulointerstitial fibrosis, and we confirmed that R715 treatment here also exacerbates fibrosis (cis 0,225+0,025 cis+R715 0,345+0,042). Conclusion Here we show that both deletion and blockage of kinin B1 receptor has deleterious effects in renal injury and fibrosis induced by ongoing cisplatin treatment.

Process Intensification for the Purification of Peptidomimetics: The Case of Icatibant through Multicolumn Countercurrent Solvent Gradient Purification (MCSGP)

Biopharmaceuticals are subjected to very strict purity requirements to be marketed. At the same time, peptides and other biomolecules are industrially synthesized through techniques (e.g., solid-phase synthesis) often leading to the formation of many impurities with molecular characteristics very similar to the target product. Therefore, the purification of these mixtures via preparative chromatography can be very challenging. This typically involves ternary or central-cut separations, characterized by chromatograms where the central peak, corresponding to the target product, exhibits significant overlapping on both sides with impurities slightly more or less adsorbable. In single-column (batch) preparative chromatography, this leads to a typical yield-purity tradeoff, meaning that high purity can be obtained at the cost of low yield and vice versa, with obvious consequences on the overall production costs. This study demonstrates how this limitation can be alleviated using the continuous countercurrent operating mode, conducted on a multicolumn system, as a tool for process intensification. In particular, the Multicolumn Countercurrent Solvent Gradient Purification (MCSGP) process has been applied to the purification of an industrial crude mixture of icatibant, which is a peptidomimetic antagonist of bradykinin B2-receptor that has been recently also considered for the treatment of patients affected by COVID-19 disease. It is shown that MCSGP allows conjugating process simplicity (using only two columns) with a significant improvement in process performance, compared to the corresponding batch process. This includes all process performance parameters: yield, productivity, and buffer consumption for a given purity specification of icatibant.

Myocardial angiogenesis induced by exercise training involves a regulatory mechanism mediated by kinin receptors

ABSTRACT Objective: To demonstrate that the kallikrein-kinin system (KKS) is upstream of angiogenic signaling pathway, and to determine the role of the kinin B1 and B2 receptors in myocardial angiogenesis induced by exercise training. Methods: Forty Wistar rats were randomly assigned to an exercise control (EC) group, a B1 receptor antagonist (B1Ant) group, a B2 receptor antagonist (B2Ant) group, and a double receptor antagonist ((B1+ B2)Ant) group. A myocardial infarction model was employed. Animals in all groups received 30 min of exercise training for 4 weeks. The expression of VEGF and eNOS, capillary supply, and apoptosis rate were evaluated. Results: The mRNA and protein expression of VEGF and eNOS showed similar trends in all groups, and were lowest in the (B1+ B2) Ant group, and highest in the EC group. Levels of VEGF and eNOS mRNA were significantly lower in the B1Ant group than in the B2Ant group (p< .001 and p< .05, respectively). VEGF and eNOS protein in the B1Ant group was also significantly lower (p< .01 and p< .05, respectively) than in the B2Ant group. The capillary numbers in the (B1+ B2) Ant group were significantly lower than in the EC group (395.8 ± 105 vs. 1127.9 ± 192.98, respectively). The apoptosis rate of cardiomyocytes was highest in the (B1+ B2) Ant group. Conclusion: KKS may act as an upstream signal transduction pathway for angiogenic factors in myocardial angiogenesis. The B1 and B2 receptors exert additive effects, and the B1 receptor has the most prominent role in mediating KKS-induced myocardial angiogenesis.

Real-world off-label use of icatibant for acute management of non-hereditary angioedema.

We retrospectively examined the indications and efficacy of off-label use of the bradykinin B2 receptor antagonist icatibant. The clinical heterogeneity, variability of response to icatibant and lack of efficacy of adrenaline described in this audit highlights both the need for biomarkers that can rapidly distinguish between histaminergic and non-histaminergic angioedema, and for guidelines to improve the utility of icatibant in the non-hereditary angioedema setting.

A case of hereditary angioedema due to C1-inhibitor deficiency with recurrent abdominal pain diagnosed 40 years after the occurrence of the initial symptom

Hereditary angioedema due to C1-inhibitor deficiency (HAE-C1-INH) is a rare disease, which induces an acute attack of angioedema mediated by bradykinin. HAE-C1-INH can cause serious abdominal pain when severe edema develops in the gastrointestinal tract. However, because it takes a long time, 13.8 years on average in Japan, from the occurrence of the initial symptom to the diagnosis due to low awareness of the disease, undiagnosed HAE-C1-INH patients sometimes undergo unnecessary surgical procedures for severe abdominal pain. We herein present a 56-year-old patient with HAE-C1-INH, who underwent numerous abdominal operations. He frequently needed hospitalization with the administration of opioid due to severe abdominal pain. However, after he was accurately diagnosed with HAE-C1-INH at 55 years of age, he could start self-administration for an acute attack with icatibant, a selective bradykinin B2 receptor antagonist. Consequently, he did not need hospitalizing for ten months after the beginning of the treatment. A series of an accurate diagnosis and appropriate treatment for HAE-C1-INH improved his quality of life. Thus, HAE-C1-INH should be considered, when we meet patients with unidentified recurrent abdominal pain. This case highlights significance of an early diagnosis and appropriate treatment for HAE-C1-INH.

Inhibitors of angiotensin I converting enzyme potentiate fibromyalgia-like pain symptoms via kinin receptors in mice

Fibromyalgia is a potentially disabling chronic disease, characterized by widespread pain and a range of comorbidities such as hypertension. Among the mechanisms involved in fibromyalgia-like pain symptoms are kinins and their B1 and B2 receptors. Moreover, angiotensin I converting enzyme (ACE) inhibitors, commonly used as antihypertensive drugs, can enhance pain by blocking the degradation of peptides such as substance P and bradykinin, besides enhancing kinin receptors signalling. We investigated the effect of ACE inhibitors on reserpine-induced fibromyalgia-like pain symptoms and the involvement of kinins in this effect in mice. Nociceptive parameters (mechanical and cold allodynia and overt nociception) were evaluated after ACE inhibitors administration in mice previously treated with reserpine. The role of kinin B1 and B2 receptors was investigated using pharmacological antagonism. Additionally, bradykinin levels, as well as the activity of ACE and kininase I, were measured in the sciatic nerve, spinal cord and cerebral cortex of the mice. The ACE inhibitors enalapril and captopril enhanced reserpine-induced mechanical allodynia, and this increase was prevented by kinin B1 and B2 receptor antagonists. Substance P and bradykinin caused overt nociception and increased mechanical allodynia in animals treated with reserpine. Reserpine plus ACE inhibitors increased bradykinin-related peptide levels and inhibited ACE activity in pain modulation structures. Since hypertension is a frequent comorbidity affecting fibromyalgia patients, hypertension treatment with ACE inhibitors in these patients should be reviewed once this could enhance fibromyalgia-like pain symptoms. Thus, the treatment of hypertensive patients with fibromyalgia could include other classes of antihypertensive drugs, different from ACE inhibitors.

Receptor mechanism of infarct-limiting effect of adaptation to normobaric hypoxia

The aim of the study was to investigate the involvement of bradykinin, cannabinoid and vanilloid (TRPV1 channel) receptors in the implementation of the infarct-limiting effect of chronic normobaric hypoxia (CNH). Materials and methods . The study was performed on male Wistar rats ( n = 117) weighing 250–300 g. Adaptation to CNH was modeled for 21 days at 12% pO 2 , 0.3% pCO 2 and normal atmospheric pressure. A day after adaptation of rats to CNH coronary artery occlusion (45 min) and reperfusion (2 h) was performed. In the study the following compounds were used: selective cannabinoid CB1 receptor antagonist rimonabant (1 mg/kg), selective cannabinoid CB2 receptor antagonist AM630 (2.5 mg/kg), selective bradykinin B2 receptor antagonist HOE140 (50 μg/kg), and vanilloid receptor (TRPV1 channel) antagonist capsazepine (3 mg/kg). All antagonists were administered 15 min before coronary artery occlusion. Results. Adaptation to normobaric hypoxia promoted the formation of the pronounced infarct-limiting effect. The blockade of B2 receptor eliminated the infarct-limiting effect of CNH. Blockade of cannabinoid or vanilloid receptors did not affect the infarct-limiting effect of CNH. Conclusion . The infarct-limiting effect of CNH depends on the activation of B2 receptor, and the adaptive increase in cardiac tolerance to ischemia/reperfusion does not depend on cannabinoid or vanilloid receptors.

Renal fibrosis due to multiple cisplatin treatment is exacerbated by kinin B1 receptor antagonism.

Cisplatin is a widely used chemotherapeutic drug, but its side effects are a major limiting factor. Nephrotoxicity occurs in one third of patients undergoing cisplatin treatment. The acute tubular injury caused by cisplatin often leads to a defective repair process, which translates into chronic renal disorders. In this way, cisplatin affects tubular cells, and maladaptive tubules regeneration will ultimately result in tubulointerstitial fibrosis. Kinins are well known for being important peptides in the regulation of inflammatory stimuli, and kinin B1 receptor deficiency and antagonism have been shown to be beneficial against acute cisplatin nephrotoxicity. This study aimed to analyze the effects of kinin B1 receptor deletion and antagonism against repeated cisplatin-induced chronic renal dysfunction and fibrosis. Both the deletion and the antagonism of B1 receptor exacerbated cisplatin-induced chronic renal dysfunction. Moreover, the inhibition of B1 receptor increased tubular injury and tubulointerstitial fibrosis after repeated treatment with cisplatin. The balance between M1/M2 macrophage polarization plays an important role in renal fibrosis. Kinin B1 receptor antagonism had no impact on M1 markers when compared to cisplatin. However, YM1, an M2 marker and an important molecule for the wound healing process, was decreased in mice treated with kinin B1 receptor antagonist, compared to cisplatin alone. Endothelin-1 levels were also increased in mice with B1 receptor inhibition. This study showed that kinin B1 receptor inhibition exacerbated cisplatin-induced chronic renal dysfunction and fibrosis, associated with reduced YM1 M2 marker expression, thus possibly affecting the wound healing process.

Type 2 hereditary angioedema treated with acute exacerbation with icatibant: A case report

Hereditary angioedema (HAE) is a rare autosomal dominant disorder caused by genetic deficiency or decreased function of C1-es terase inhibitor. It is characterized by swelling of subcutaneous and submucosal tissues of the extremities, gastrointestinal tract, and upper airways which can be life-threatening. Thus, early recognition and treatment of the disease are important. Short- and long-term prophylaxes are used to decrease the severity and frequency of attacks. Icatibant is a selective bradykinin B2-receptor antago nist, earlier treatment of acute attacks and hospital admission. The authors present a case of 47-year-old woman who was diag nosed with type II HAE, danazol as a long term. Her symptoms improved dramatically after drug treatment. The unpredictability and recurrence of HAE attacks could have a negative impact on social life and quality of life. This case shows that timely and proper treat ment could improve quality of life and reduce morbidity and mortality. (Allergy Asthma Respir Dis 2021;9:180-183)

The role of TRPA1 and TRPV4 channels in bronchoconstriction and plasma extravasation in airways of rats treated with captopril

Angiotensin-converting enzyme inhibitors (ACEis) may cause adverse airway events, such as cough and angioedema, due to a reduction in bradykinin breakdown and consequent activation of bradykinin type 2 receptor (B2 receptor). Recent studies have shown that bradykinin can also sensitize pro-inflammatory receptors such as the transient receptor potential ankyrin 1 (TRPA1) and vanilloid 4 (TRPV4), which are implicated in several inflammatory airway diseases. Based on these considerations, the aim of this study was to understand the role of TRPA1 and TRPV4 channels in the bronchoconstrictive response and plasma extravasation in the trachea of rats pretreated with captopril. Using methods to detect alterations in airway resistance and plasma extravasation, we found that intravenous (i.v.) administration of bradykinin (0.03–0.3 μmol/kg, B2 receptor agonist), allyl isothiocyanate (100–1000 μmol/kg, TRPA1 agonist) or GSK1016790A (0.01–0.1 μmol/kg, TRPV4 agonist), but not des-arg9-bradykinin (DABK; 100–300 μmol/kg, B1 receptor agonist), induced bronchoconstriction in anaesthetized rats. In doses that did not cause significant bronchoconstriction, bradykinin (0.03 μmol/kg) or allyl isothiocyanate (100 μmol/kg), but not GSK1016790A (0.01 μmol/kg) or DABK (300 μmol/kg) induced an increased bronchoconstrictive response in rats pretreated with captopril (2.5 mg/kg, i.v.). On the other hand, in rats pretreated with captopril (5 mg/kg, i.v.), an increased bronchoconstrictive response to GSK1016790A (0.01 μmol/kg) was observed. The bronchoconstrictive response induced by bradykinin in captopril-pretreated rats was inhibited by intratracheal treatment (i.t.) with HC030031 (300 μg/50 μl; 36 ± 9%) or HC067047 (300 μg/50 μl; 35.1 ± 16%), for TRPA1 and TRPV4 antagonists, respectively. However, the co-administration of both antagonists did not increase this inhibition. The bronchoconstriction induced by allyl isothiocyanate in captopril-pretreated rats (2.5 mg/kg) was inhibited (58.3 ± 8%) by the B2 receptor antagonist HOE140 (10 nmol/50 μl, i.t.). Similarly, the bronchoconstriction induced by GSK1016790A in captopril-pretreated rats (5 mg/kg) was also inhibited (84.2 ± 4%) by HOE140 (10 nmol/50 μl, i.t.). Furthermore, the plasma extravasation induced by captopril on the trachea of rats was inhibited by pretreatment with HC030031 (47.2 ± 8%) or HC067047 (38.9 ± 8%). Collectively, these findings support the hypothesis that TRPA1 and TRPV4, via a B2 receptor activation-dependent pathway, are involved in the plasma extravasation and bronchoconstriction induced by captopril, making them possible pharmacological targets to prevent or remediate ACEi-induced adverse respiratory reactions.

Kinin B1 receptor is involved in mechanical nociception in a fibromyalgia-like model in mice

Fibromyalgia-like models in mice induced by reserpine have opened a new avenue to understanding the molecular mechanisms behind this complex and incapacitating pain syndrome. The kinin B1 receptor (B1R) contributes to mechanical allodynia and acute coping behavior in mice with inflammatory and immunological disorders. This study has replicated previous data where amine depletion induced by reserpine significantly decreased the dopamine and serotonin levels in the prefrontal cortex (PFC), hippocampus (HPC), and spinal cord of mice. The animals subjected to the reserpine fibromyalgia model also showed decreased paw withdrawal threshold (PWT) and increased the immobility time in the forced swimming test (FST). Genetic ablation of B1R or pharmacological blockade by selective kinin B1R antagonist R-715 (acute i.p. treatment) counteracted the mechanical allodynia and increased immobility time induced by reserpine. However, neither pharmacological nor genetic inhibition of B1R reversed monoamine depletion. Our data confirm that reserpine induced a fibromyalgia-like phenotype in mice and reiterated the role of B1R on acute coping behavior and nociception modulation.

Review of icatibant use in the Winnipeg Regional Health Authority

BackgroundThis is a retrospective review of the Winnipeg Regional Health Authority’s (WRHA) angioedema patients who were dispensed icatibant in hospital. Icatibant is a bradykinin B2 receptor antagonist indicated for Hereditary Angioedema (HAE) types I and II and is used off-label for HAE with normal C1INH (HAE-nC1INH) and ACE-inhibitor induced angioedema (ACEIIAE). The WRHA’s use of icatibant is regulated by the Allergist on call. We characterized icatibant's use and the timeline from patient presentation, compared the real-world experience with the FAST-3 trial and hypothesized the factors which may affect response to icatibant.MethodsBackground data were collected on patients. Angioedema attack-related data included administered medications, performed investigations and the timeline to endpoints such as onset of symptom relief. Data was analyzed in R with the package “survival.” Time-to-event data was analyzed using the Peto–Peto Prentice method or Mann–Whitney U-test. Data was also compared with published clinical trial data using the Sign Test. Fisher’s Exact Test was used to produce descriptive statistics.ResultsOverall, 21 patients accounted for 23 angioedema attacks treated with icatibant. Approximately half the patients had a diagnosis of HAE-nC1IHN and half of ACEIIAE. Of those presenting with angioedema, 65% were first treated with conventional medication. Patients without a prior angioedema diagnosis were evaluated only 40–50% of the time for C4 levels or C1INH function or level. The median time from patients’ arrival to the emergency department until the Allergy consultant’s response was 1.77 h. Patients with HAE-nC1IHN had median times to onset of symptom relief and final clinical outcome (1.13 h, p = 0.34; 3.50 h, p = 0.11) similar to those reported in FAST-3 for HAE I/II. Patients with ACEIIAE had longer median times to onset of symptom relief (4.86 h, p = 0.01) than predicted.ConclusionsHAE-nC1INH may be an appropriate indication for treatment with icatibant. Conversely, the results of this study do not support the use of icatibant for the treatment of ACEIIAE, concordant with a growing body of literature. Patients should be stratified into groups of more- or less-likely icatibant-responders through history and laboratory investigations in order to prevent potential delays.

P152 PHA-022121, A SELECTIVE BRADYKININ-B2-RECEPTOR ANTAGONIST, IS SAFE AND SHOWS RAPID ORAL BIOAVAILABILITY IN HUMANS

Bradykinin B2 receptor antagonism has been demonstrated to be effective in treating acute HAE attacks, but is currently not available as oral treatment. PHA-022121 is a first-in-class oral small molecule, highly selective for B2 receptor antagonist with superior potency and pharmacological activity in animal models.

Binding Mode Exploration of B1 Receptor Antagonists' by the Use of Molecular Dynamics and Docking Simulation-How Different Target Engagement Can Determine Different Biological Effects.

The kinin B1 receptor plays a critical role in the chronic phase of pain and inflammation. The development of B1 antagonists peaked in recent years but almost all promising molecules failed in clinical trials. Little is known about these molecules’ mechanisms of action and additional information will be necessary to exploit the potential of the B1 receptor. With the aim of contributing to the available knowledge of the pharmacology of B1 receptors, we designed and characterized a novel class of allosteric non-peptidic inhibitors with peculiar binding characteristics. Here, we report the binding mode analysis and pharmacological characterization of a new allosteric B1 antagonist, DFL20656. We analyzed the binding of DFL20656 by single point mutagenesis and radioligand binding assays and we further characterized its pharmacology in terms of IC50, B1 receptor internalization and in vivo activity in comparison with different known B1 antagonists. We highlighted how different binding modes of DFL20656 and a Merck compound (compound 14) within the same molecular pocket can affect the biological and pharmacological properties of B1 inhibitors. DFL20656, by its peculiar binding mode, involving tight interactions with N114, efficiently induced B1 receptor internalization and evoked a long-lasting effect in an in vivo model of neuropathic pain. The pharmacological characterization of different B1 antagonists highlighted the effects of their binding modes on activity, receptor occupancy and internalization. Our results suggest that part of the failure of most B1 inhibitors could be ascribed to a lack of knowledge about target function and engagement.

Kinin B2 Receptor Activation Prevents the Evolution of Alzheimer's Disease Pathological Characteristics in a Transgenic Mouse Model.

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.

Hereditary Angioedema Due to C1-Inhibitor Deficiency in Romania: First National Study, Diagnostic and Treatment Challenges.

Hereditary angioedema (HAE) is a rare genetic potentially life-threatening disease characterized by episodic non-pruritic subcutaneous and submucosal edema attacks in different parts of the body. To assess the status of Romanian HAE patients after the recent introduction of a new therapy through a nationwide program. This cross-sectional observational study included patients from the Romanian HAE Registry. The study included 84 patients with HAE type I (91.7%) and type II (8.3%). The mean delay in diagnosis was 2.4 years in children and 16.7 years in adults (p=0.019). Stress and tiredness were the most frequent trigger factors. The majority of the HAE episodes involved subcutaneous (89.3%), abdominal (77.4%), genital (51.2%), facial (41.7%), and laryngeal (39.3%) symptoms during the preceding 12 months. One or several misdiagnoses were reported in 83.33% patients and 44.1 % of the patients were subjected to or proposed unnecessary surgery during abdominal episodes. Plasma-derived C1-INH (pdC1-INH) and recombinant C1-INH (rhC1-INH) were respectively used in 10 (11.9%) and 13 (15.5%) of the HAE patients for life-threatening attacks over the past 12 months. Forty-three (51.19%) patients practiced home treatment with subcutaneous injection of the bradykinin B2-receptor antagonist for acute HAE attacks. The significantly lower delay observed in children suggests an improvement in the awareness of C1-INH-HAE among physicians in recent years. The management of HAE in Romania has been somewhat enhanced as the majority of HAE patients have recently gained access to pdC1-INH, rhC1-INH, and bradykinin B2-receptor antagonist.

In Vitro Modeling of Bradykinin-Mediated Angioedema States.

Kinins (peptides related to bradykinin, BK) are formed from circulating substrates, the kininogens, by the action of two proteases, the kallikreins. The only clinical application of a BK receptor ligand, the B2 receptor antagonist icatibant, is the treatment of the rare hereditary angioedema (HAE) caused by the deficiency of C1-esterase inhibitor (C1-INH). Less common forms of HAE (genetic variants of factor XII, plasminogen, kininogen) are presumably mediated by increased BK formation. Acquired forms of BK-mediated angioedema, such as that associated with angiotensin-I converting enzyme (ACE) inhibition, are also known. Antibody-based analytical techniques are briefly reviewed, and support that kinins are extremely short-lived, prominently cleared by ACE. Despite evidence of continuous activation of the kallikrein–kinin system in HAE, patients are not symptomatic most of the time and their blood or plasma obtained during remission does not generate excessive immunoreactive BK (iBK), suggesting effective homeostatic mechanisms. HAE-C1-INH and HAE-FXII plasmas are both hyperresponsive to fibrinolysis activation. On another hand, we suggested a role for the alternate tissue kallikrein–kinin system in patients with a plasminogen mutation. The role of the BK B1 receptor is still uncertain in angioedema states. iBK profiles under in vitro stimulation provide fresh insight into the physiopathology of angioedema.