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Hereditary angioedema (HAE) is a rare, potentially life‐threatening genetic disorder characterized by recurrent attacks of swelling. Local vasodilation and vascular leakage are stimulated by the vasoactive peptide bradykinin, which is excessively produced due to dysregulation of the activated factor XII (FXIIa)‐driven kallikrein–kinin system. There is a need for novel treatments for HAE that provide greater efficacy, improved quality of life, minimal adverse effects, and reduced treatment burden over current first‐line therapies. FXIIa is emerging as an attractive therapeutic target for interference with HAE attacks. In this review, we draw on preclinical, experimental animal, and in vitro studies, providing an overview on targeting FXIIa as the basis for pharmacologic interference in HAE. We highlight that there is a range of FXIIa inhibitors in development for different therapeutic areas. Of these, garadacimab, an FXIIa‐targeted inhibitory monoclonal antibody, is the most advanced and has shown potential as a novel long‐term prophylactic treatment for patients with HAE in clinical trials. The evidence from these trials is summarized and discussed, and we propose areas for future research where targeting FXIIa may have therapeutic potential beyond HAE. [ABSTRACT FROM AUTHOR]

Hereditary angioedema is a rare, genetic disorder characterized by painful, debilitating and potentially life-threatening angioedema attacks in subcutaneous and submucosal tissue. While usually unpredictable, attacks can be provoked by a variety of triggers including physical injury and certain medication and are often preceded by prodromal symptoms. Hereditary angioedema has a profound influence on the patients' lives. The fundamental cause of hereditary angioedema in almost all patients is a mutation in the SERPING1 gene leading to a deficiency in C1-inhibitor. Subsequently, the contact activation cascade and kallikrein-kinin pathway are insufficiently inhibited, resulting in excessive bradykinin production triggering vascular leakage. While C1-inhibitor is an important regulator of the intrinsic coagulation pathway, fibrinolytic system and complement cascade, patients do not have an increased risk of coagulopathy, autoimmune conditions or immunodeficiency disorders. Hereditary angioedema is diagnosed based on C1-inhibitor level and function. Genetic analysis is only required in rare cases where hereditary angioedema with normal C1-inhibitor is found. In recent years, new, highly specific therapies have greatly improved disease control and angioedema-related quality of life. This article reviews the clinical picture of hereditary angioedema, the underlying pathophysiology, diagnostic process and currently available as well as investigational therapeutic options. [ABSTRACT FROM AUTHOR]

Background and Purpose: Psoriasis is an autoimmune inflammatory skin disease, featuring microvascular abnormalities and elevated levels of bradykinin. Contact activation of Factor XII can initiate the plasma kallikrein‐kinin cascade, producing inflammation and angioedema. The role of Factor XII in psoriasis is unknown. Experimental Approach: The effects of deficiency of Factor XII or its enzymatic substrate, prekallikrein, were examined in the imiquimod‐induced mouse model of psoriasis. Skin microcirculation was assessed using intravital confocal microscopy and laser Doppler flowmeter. A novel antibody blocking Factor XII activation was evaluated for psoriasis prevention. Key Results: Expression of Factor XII was markedly up‐regulated in human and mouse psoriatic skin. Genetic deletion of Factor XII or prekallikrein, attenuated imiquimod‐induced psoriatic lesions in mice. Psoriatic induction increased skin microvascular blood perfusion, causing vasodilation, hyperpermeability and angiogenesis. It also promoted neutrophil‐vascular interaction, inflammatory cytokine release and enhanced Factor XII / prekallikrein enzymatic activity with elevated bradykinin. Factor XII or prekallikrein deficiency ameliorated these microvascular abnormalities and abolished bradykinin increase. Antagonism of bradykinin B2 receptors reproduced the microvascular protection of Factor XII / prekallikrein deficiency, attenuated psoriatic lesions, and prevented protection by Factor XII / prekallikrein deficiency against psoriasis. Furthermore, treatment of mice with Factor XII antibody alleviated experimentally induced psoriasis and suppressed microvascular inflammation. Conclusion and Implications: Activation of Factor XII promoted psoriasis via prekallikrein‐dependent formation of bradykinin, which critically mediated psoriatic microvascular inflammation. Inhibition of contact activation represents a novel therapeutic strategy for psoriasis. [ABSTRACT FROM AUTHOR]

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Evidence suggests that angiotensin-converting enzyme inhibitors (ACEIs) may increase metabolic rate by promoting thermogenesis, potentially through enhanced fat oxidation and improved insulin. More research is, however, needed to understand this intricate process. In this study, we used 22 lines from the Drosophila Genetic Reference Panel to assess the metabolic rate of virgin female and male flies that were either fed a standard medium or received lisinopril for one week or five weeks. We demonstrated that lisinopril affects the whole-body metabolic rate in Drosophila melanogaster in a genotype-dependent manner. However, the effects of genotypes are highly context-dependent, being influenced by sex and age. Our findings also suggest that lisinopril may increase the Drosophila metabolic rate via the accumulation of a bradykinin-like peptide, which, in turn, enhances cold tolerance by upregulating Ucp4b and Ucp4c genes. Finally, we showed that knocking down Ance, the ortholog of mammalian ACE in Malpighian/renal tubules and the nervous system, leads to opposite changes in metabolic rate, and that the effect of lisinopril depends on Ance in these systems, but in a sex- and age-specific manner. In conclusion, our results regarding D. melanogaster support existing evidence of a connection between ACEI drugs and metabolic rate while offering new insights into this relationship. [ABSTRACT FROM AUTHOR]

Myocardial ischemia causes the release of bradykinin, which activates afferent nerve endings in the ventricular epicardium. This elicits a sympathetically mediated increase in arterial pressure and heart rate, referred to as the cardiogenic sympathetic afferent reflex. The rostroventrolateral medulla (RVLM) is a key sympathetic brain stem site for regulating cardiovascular activity. This study aimed to determine the importance of non‐barosensitive nociception sympathetic activity and the role of glutamate receptor activation of RVLM neurons in the cardiogenic sympathetic afferent reflex. We tested the hypothesis that inhibition of barosensitive sympathetic activity attenuates but does not abolish the reflex response to cardiac visceral afferents. Renal sympathetic nerve activity (RSNA), arterial pressure, and heart rate responses to epicardial bradykinin application were recorded in anesthetized rats before and after bilateral RVLM microinjection of either GABAA agonist muscimol, ionotropic glutamate receptor antagonist kynurenic acid, N‐methyl‐d‐aspartate (NMDA) receptor antagonist 2‐amino‐5‐ phosphonopentanoic acid (AP5), or non‐NMDA antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX). Baroreceptor loading‐induced inhibition of barosensitive activity attenuated the bradykinin‐induced RSNA response (93 ± 14% increase) and tachycardia (18 ± 3 bpm). While RVLM muscimol microinjection abolished the RSNA response (1.6 ± 4.2% from baseline, 0.49 ± 0.38 μV*s), surprisingly, it did not abolish the tachycardia (27 ± 4 bpm). Kynurenic acid microinjection blocked the arterial pressure and RSNA responses, while AP5 or CNQX only attenuated the responses. These data suggest that nociception‐sensitive sympathetic activity that does not appear to be barosensitive is also involved in the cardiogenic sympathetic afferent reflex. Importantly, while muscimol and kynurenic acid abolished the arterial pressure and RSNA response, neither affected the tachycardia, suggesting an alternate cardiac pathway independent of RVLM. [ABSTRACT FROM AUTHOR]

Glioblastomas synthesize, bear receptors for, and respond to bradykinin, triggering migration and proliferation. Since centrifugal migration into uninvolved surrounding brain tissue occurs early in the course of glioblastoma, this attribute defeats local treatment attempts and is the primary reason current treatments almost always fail. Stopping bradykinin-triggered migration would be a step closer to control of this disease. The recent approval and marketing of an oral plasma kallikrein inhibitor, berotralstat (Orladeyo™), and pending FDA approval of a similar drug, sebetralstat, now offers a potential method for reducing local bradykinin production at sites of bradykinin-mediated glioblastoma migration. Both drugs are approved for treating hereditary angioedema. They are ideal for repurposing as a treatment adjunct in glioblastoma. Furthermore, it has been established that peritumoral edema, a common problem during the clinical course of glioblastoma, is generated in large part by locally produced bradykinin via kallikrein action. Both brain edema and the consequent use of corticosteroids both shorten survival in glioblastoma. Therefore, by (i) migration inhibition, (ii) growth inhibition, (iii) edema reduction, and (iv) the potential for less use of corticosteroids, berotralstat may be of service in treatment of glioblastoma, slowing disease progression. This paper recounts the details and past research on bradykinin in glioblastoma and the rationale of treating it with berotralstat. [ABSTRACT FROM AUTHOR]

Escin, extracted from horse chestnut (Aesculus hippocastanum) has anti-edema and anti-inflammatory effects. It is used to treat several clinical conditions, including venous insufficiency, pain, inflammation, and edema. Considering escin's pharmacodynamic, the inhibition of the bradykinin pathway represents a particular effect, decreasing the local edema and conferring an advantage in comparison to other compounds. In this narrative review, we described the effects of escin considering its effects on bradykinin pathway. [ABSTRACT FROM AUTHOR]

Abstract Myocardial ischemia causes the release of bradykinin, which activates afferent nerve endings in the ventricular epicardium. This elicits a sympathetically mediated increase in arterial pressure and heart rate, referred to as the cardiogenic sympathetic afferent reflex. The rostroventrolateral medulla (RVLM) is a key sympathetic brain stem site for regulating cardiovascular activity. This study aimed to determine the importance of non‐barosensitive nociception sympathetic activity and the role of glutamate receptor activation of RVLM neurons in the cardiogenic sympathetic afferent reflex. We tested the hypothesis that inhibition of barosensitive sympathetic activity attenuates but does not abolish the reflex response to cardiac visceral afferents. Renal sympathetic nerve activity (RSNA), arterial pressure, and heart rate responses to epicardial bradykinin application were recorded in anesthetized rats before and after bilateral RVLM microinjection of either GABAA agonist muscimol, ionotropic glutamate receptor antagonist kynurenic acid, N‐methyl‐d‐aspartate (NMDA) receptor antagonist 2‐amino‐5‐ phosphonopentanoic acid (AP5), or non‐NMDA antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX). Baroreceptor loading‐induced inhibition of barosensitive activity attenuated the bradykinin‐induced RSNA response (93 ± 14% increase) and tachycardia (18 ± 3 bpm). While RVLM muscimol microinjection abolished the RSNA response (1.6 ± 4.2% from baseline, 0.49 ± 0.38 μV*s), surprisingly, it did not abolish the tachycardia (27 ± 4 bpm). Kynurenic acid microinjection blocked the arterial pressure and RSNA responses, while AP5 or CNQX only attenuated the responses. These data suggest that nociception‐sensitive sympathetic activity that does not appear to be barosensitive is also involved in the cardiogenic sympathetic afferent reflex. Importantly, while muscimol and kynurenic acid abolished the arterial pressure and RSNA response, neither affected the tachycardia, suggesting an alternate cardiac pathway independent of RVLM.

Glioblastomas synthesize, bear receptors for, and respond to bradykinin, triggering migration and proliferation. Since centrifugal migration into uninvolved surrounding brain tissue occurs early in the course of glioblastoma, this attribute defeats local treatment attempts and is the primary reason current treatments almost always fail. Stopping bradykinin-triggered migration would be a step closer to control of this disease. The recent approval and marketing of an oral plasma kallikrein inhibitor, berotralstat (Orladeyo™), and pending FDA approval of a similar drug, sebetralstat, now offers a potential method for reducing local bradykinin production at sites of bradykinin-mediated glioblastoma migration. Both drugs are approved for treating hereditary angioedema. They are ideal for repurposing as a treatment adjunct in glioblastoma. Furthermore, it has been established that peritumoral edema, a common problem during the clinical course of glioblastoma, is generated in large part by locally produced bradykinin via kallikrein action. Both brain edema and the consequent use of corticosteroids both shorten survival in glioblastoma. Therefore, by (i) migration inhibition, (ii) growth inhibition, (iii) edema reduction, and (iv) the potential for less use of corticosteroids, berotralstat may be of service in treatment of glioblastoma, slowing disease progression. This paper recounts the details and past research on bradykinin in glioblastoma and the rationale of treating it with berotralstat.

An efficient calculation tool for rigorously optimizing the instrument parameters of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) is demonstrated in this work. Optimization of MALDI‐TOF MS has been an experience‐based, time‐consuming process without a rigorous theoretical principle. Based on the comprehensive calculation model reported previously, we developed a software tool, MAXTOF, to rapidly determine instrument parameters providing ultimate mass resolving power (MRP). The software conducts big data analysis of most instrument parameters to predict the MRP, including instrument dimensions, voltages, mass‐to‐charge ratio of ions, and ion extraction delay. It can complete the calculation in seconds, providing parameters that serve as the starting point for subsequent optimization that greatly accelerates the optimization process. Experimental validation using a commercial instrument demonstrates MAXTOF's efficacy in predicting optimal parameters and enhancing MRP. The predicted ion extraction delays for bradykinin fragment, P14R polypeptide, and insulin chain B ions were within 5% of the values observed through long‐term optimization. The observed MRP of those ions ranged from 2800 to 4500. Results show that the method and software are highly advantageous for fast and precise measurements. [ABSTRACT FROM AUTHOR]

The present study investigates the distribution and dynamics of gonadotropin-releasing hormone I (GnRH I) and bradykinin in the air-breathing catfish, Heteropneustes fossilis, in relation to the reproductive cycle. Changes in bradykinin, bradykinin B2-receptor, and ovarian GnRH I regulation were demonstrated during the reproductive cycle. The localization of GnRH I, bradykinin, and their respective receptors in the ovaries was investigated by immunohistochemistry, while their levels were quantified by slot/western blot followed by densitometry. GnRH I and its receptor were mainly localized in the cytoplasm of oocytes during the early previtellogenic phase. However, as the follicles grew larger, immunoreactivity was observed in the granulosa and theca cells of the late previtellogenic follicles. The ovaries showed significantly higher expression of GnRH I protein and its receptor during the early to mid-previtellogenic phase, suggesting their involvement in follicular development. Bradykinin and bradykinin B 2 -receptor showed a distribution pattern similar to that of GnRH I and its receptor. This study further suggested the possibility that bradykinin regulates GnRH I synthesis in the ovary. Thus, we show that the catfish ovary has a GnRH-bradykinin system and plays a role in follicular development and oocyte maturation in H. fossilis. • Catfish, Heteropneustes fossilis ovary possess GnRH I and bradykinin system. • GnRH I and bradykinin and their receptors are present in the same cell types during different phase of reproductive cycle. • GnRH I, bradykinin and their receptors were highest during previtellogenic phase which decreased in later phases. • We hypothesized bradykinin may act as a regulator of GnRH in the ovaries of H. fossilis. [ABSTRACT FROM AUTHOR]

Irritant contact dermatitis (ICD) is a nonspecific skin inflammation caused by irritants, leading to itch and pain. We tested whether differential responses to histamine-dependent and -independent pruritogens can be evoked in ICD induced by sodium lauryl sulfate (SLS). An ICD mouse model was established with 5% SLS in acetone versus a vehicle topically applied for 24 h to the cheek. Site-directed itch- and pain-like behaviors, occurring spontaneously and in response to mechanical, thermal, and chemical stimuli (histamine, ß-alanine, BAM8-22, and bradykinin) applied to the cheek, were recorded before (day 0) and after irritant removal (days 1, 2, 3, and 4). Skin inflammation was assessed through visual scoring, ultrasound, and measurements of skin thickness. SLS-treated mice exhibited hyperalgesia-like behavior in response to mechanical and heat stimuli on day 1 compared to the controls. SLS mice exhibited more spontaneous wipes (pain) but not scratching bouts (itch) on day 1. Pruritogen injections caused more scratching but not wiping in SLS-treated mice compared to the controls. Only bradykinin increased wiping behavior compared to saline. SLS-treated mice developed noticeable erythema, scaling, and increased skin thickness on days 1 and 2. SLS induced cutaneous inflammation and behavioral signs of spontaneous pain and itching, hyperalgesia to mechanical and heat stimuli and a chemical algogen, and enhanced itch response to pruritogens. These sensory reactions preceded the inflammation peak and lasted up to two days. [ABSTRACT FROM AUTHOR]

Hereditary angioedema is a potentially life-threatening autosomal dominant connology dition, causing attacks of angioedema due to failure to regulate bradykinin. Nearly all cases of hereditary angioedema are caused by mutations in the gene encoding Cl inhibitor, SERPINGl. Cl inhibitor is a multifunctional protein produced in the liver that regulates the kallikrein-kinin system at multiple points. An infant with genetically confirmed hereditary angioedema and low Cl inhibitor levels (but withand out previous episodes of angioedema) underwent liver tranSplantatiOn for biliary atresia, an unrelated condition. Liver transplantation led to normalization of the Cl inhibitor level and function. To our knowledge, this represents the first patient to be potentially cured of hereditary angioedema. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate BK pathway dysregulation among and between COVID-19 survivors and the deceased. METHODOLOGY: This case-control study was performed between 2020 and 2022 in Imam Hasan Hospital, Bojnurd, Iran. SARS-CoV-2 infected patients, comprising 40 deceased and 15 surviving patients, were recruited according to specific inclusion and exclusion criteria. A blood sample was taken from subjects during the disease. Blood BK levels in subjects (the groups of patients (55) and control (15)) were measured by the ELISA technique. All patients were selected from individuals over 18 years old with real-time PCR-proven SARS-CoV-2 infection. Also, the studied patients did not have metabolic syndrome (blood pressure, abdominal obesity, diabetes, cardiovascular disease). SPSS version 26 was used to compare the means. RESULTS: The blood serum BK level was significantly related to the outcome of COVID-19 disease (P=0.006) using a multiple logistic regression test. A week before death, a significant increase in the blood BK levels among deceased patients compared to survivors was seen (p=0.0001). The probability of death in patients with SARS-CoV-2 infection linearly increased by 4% (OR = 1.04) for each pg/ml increase in the BK level. CONCLUSION: There is a close relationship between the rise in BK concentration during a COVID-19 infection and the disease outcome. [ABSTRACT FROM AUTHOR]

Background/Aim. Kallikreins (KLKs) are a group of serine protease enzymes capable of cleaving protein peptide bonds. Besides, they are proteolytic enzymes that mediate the conversion of kininogen (alpha 2-globulin) to bradykinin or kallidin. T he aim o f t he s tudy w as t o examine whether KLK8 might serve as a novel stress biomarker. Methods. Twenty-four students (17 female and 7 male) were included in the study. The general and dental health of the students were evaluated in the appropriate anamnesis format. Unstimulated samples were collected by Sarstedt ® saliva collection tubes as recommended: 08.00-- 09.00 am, 12.00, and 2.00--3.00 pm on the exam day. KLK levels were measured by a KLK8 Human ELISA kit. Results. The salivary KLK8 levels in the morning (1.25 ± 0.26 pg/mL) were statistically significantly lower than the KLK8 levels pre-exam [at 12.00 (2.89 ± 0.85 pg/mL)] (p = 0.0006). There was also a significant difference in salivary KLK8 levels between pre- and post-exam (1.69 ± 0.39) time points (p = 0.0005). Conclusion. These results s how t hat the d ifferences i n s alivary K LK8 l evels might be related to the degree of stress, indicating that KLK8 may serve as a novel stress biomarker. [ABSTRACT FROM AUTHOR]

Background: Neural progenitor cells (NPCs) can be cultivated from developing brains, reproducing many of the processes that occur during neural development. They can be isolated from a variety of animal models, such as transgenic mice carrying mutations in amyloid precursor protein (APP) and presenilin 1 and 2 (PSEN 1 and 2), characteristic of familial Alzheimer's disease (fAD). Modulating the development of these cells with inflammation-related peptides, such as bradykinin (BK) and its antagonist HOE-140, enables the understanding of the impact of such molecules in a relevant AD model. Results: We performed a global gene expression analysis on transgenic neurospheres treated with BK and HOE-140. To validate the microarray data, quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) was performed on 8 important genes related to the immune response in AD such as CCL12, CCL5, CCL3, C3, CX3CR1, TLR2 and TNF alpha and Iba-1. Furthermore, comparative analysis of the transcriptional profiles was performed between treatments, including gene ontology and reactome enrichment, construction and analysis of protein-protein interaction networks and, finally, comparison of our data with human dataset from AD patients. The treatments affected the expression levels of genes mainly related to microglia-mediated neuroinflammatory responses, with BK promoting an increase in the expression of genes that enrich processes, biological pathways, and cellular components related to immune dysfunction, neurodegeneration and cell cycle. B2 receptor inhibition by HOE-140 resulted in the reduction of AD-related anomalies caused in this system. Conclusions: BK is an important immunomodulatory agent and enhances the immunological changes identified in transgenic neurospheres carrying the genetic load of AD. Bradykinin treatments modulate the expression rates of genes related to microglia-mediated neuroinflammation. Inhibiting bradykinin activity in Alzheimer's disease may slow disease progression. [ABSTRACT FROM AUTHOR]

Bradykinin (BK), a well-studied mediator of physiological and pathological processes in the peripheral system, has garnered less attention regarding its function in the central nervous system, particularly in behavioural regulation. This review delves into the historical progression of research focused on the behavioural effects of BK and other drugs that act via similar mechanisms to provide new insights into the pathophysiology and pharmacotherapy of psychiatric disorders. Evidence from experiments with animal models indicates that BK modulates defensive reactions associated with panic symptoms and the response to acute stressors. The mechanisms are not entirely understood but point to complex interactions with other neurotransmitter systems, such as opioids, and intracellular signalling cascades. By addressing the existing research gaps in this field, we present new proposals for future research endeavours to foster a new era of investigation regarding BK's role in emotional regulation. Implications for psychiatry, chiefly for panic and depressive disorders are also discussed. [ABSTRACT FROM AUTHOR]

Sebetralstat is a novel, potent, and selective oral plasma kallikrein inhibitor drug candidate in clinical development for the on-demand treatment of hereditary angioedema (HAE). Upon binding, sebetralstat induces a conformational change in the active site of plasma kallikrein, which contributes to its high potency (Ki 3 nM) and selectivity (>1500 fold) against other serine proteases. Its physiochemical properties promote both rapid dissolution in the stomach and rapid absorption in the upper intestine that contribute to its fast and efficient absorption. A single oral administration of sebetralstat rapidly provides near-complete inhibition of plasma kallikrein and blockade of high-molecular-weight kininogen cleavage as early as 15 min, which drives its clinical efficacy. In a phase 2 clinical trial, sebetralstat significantly reduced the time to beginning of symptom relief (p < 0.0001) with median times of 1.6 h (95% CI: 1.5–3.0) with sebetralstat versus 9.0 h (4.0–17.2) with placebo. KONFIDENT (NCT05259917) is a phase 3 clinical trial assessing the on-demand use of sebetralstat for HAE. If successful, this trial could support the approval of sebetralstat as the first noninvasive, on-demand treatment option to rapidly halt HAE attacks and provide fast symptom relief. [ABSTRACT FROM AUTHOR]

Carcinoid syndrome (CS) is a debilitating disease that affects approximately 20% of patients with neuroendocrine neoplasms (NEN). Due to the increasing incidence and improved overall survival of patients with NEN over recent decades, patients are increasingly suffering from chronic and refractory CS symptoms. At present, symptom control is hampered by an incomplete understanding of the pathophysiology of this syndrome. This systematic review is the first to critically appraise the available evidence for the various hormonal mediators considered to play a causative role in CS. Overall, evidence for the putative mediators of CS was scarce and often of poor quality. Based on the available literature, data are only sufficient to agree on the role of serotonin as a mediator of CS-associated diarrhea and fibrosis. A direct role for tachykinins and an indirect role of catecholamines in the pathogenesis of CS is suggested by several studies. Currently, there is insufficient evidence to link histamine, bradykinin, kallikrein, prostaglandins, or motilin to CS. To summarize, available literature only sufficiently appoints serotonin and suggests a role for tachykinins and catecholamines as mediators of CS, with insufficient evidence for other putative mediators. Descriptions of CS should be revised to focus on these proven hormonal associations to be more accurate, and further research is needed into other potential mediators. [ABSTRACT FROM AUTHOR]

Introduction: A novel LDL (low‐density lipoprotein) apheresis therapeutic option, Rheocarna, has garnered attention as an alternative therapy for chronic limb‐threating ischemia (CLTI). Bradykinin‐mediated vasodilation is involved in the effects of LDL apheresis and a decrease in blood pressure (BP), but the changes in bradykinin concentration during Rheocarna therapy are unknown. Methods: The study involved patients with CLTI treated with Rheocarna at our hospital, from April 2022 to August 2023. Results: After Rheocarna therapy, skin ulcers improved in 80% of the patients. Circuit coagulation was observed in two patients with high fibrinogen levels. A decrease in BP was observed at approximately the same time when the bradykinin concentration peaked. The peak bradykinin concentration in a patient undergoing hemodialysis at the same time was considerably lower than that in the other patients. Conclusion: This is the first report on the changes in bradykinin concentration under Rheocarna therapy. [ABSTRACT FROM AUTHOR]

BackgroundCleaved high-molecular-weight kininogen (HKa) is a disease state biomarker of kallikrein-kinin system (KKS) activation in patients with hereditary angioedema due to C1 inhibitor deficiency (HAE-C1INH), the endogenous inhibitor of plasma kallikrein (PKa).ObjectiveDevelop an HKa-specific enzyme-linked immunosorbent assay (ELISA) to monitor KKS activation in the plasma of HAE-C1INH patients.MethodsA novel HKa-specific antibody was discovered by antibody phage display and used as a capture reagent to develop an HKa-specific ELISA.ResultsSpecific HKa detection following KKS activation was observed in plasma from healthy controls but not in prekallikrein-, high-molecular-weight kininogen-, or coagulation factor XII (FXII)-deficient plasma. HKa levels in plasma collected from HAE-C1INH patients in a disease quiescent state were higher than in plasma from healthy controls and increased further in HAE-C1INH plasma collected during an angioedema attack. The specificity of the assay for PKa-mediated HKa generation in minimally diluted plasma activated with exogenous FXIIa was demonstrated using a specific monoclonal antibody inhibitor (lanadelumab, IC50 = 0.044 µM).ConclusionsAn ELISA was developed for the specific and quantitative detection of HKa in human plasma to support HAE-C1INH drug development. Improved quantification of the HKa biomarker may facilitate further pathophysiologic insight into HAE-C1INH and other diseases mediated by a dysregulated KKS and may enable the design of highly potent inhibitors targeting this pathway.

Sebetralstat is a novel, potent, and selective oral plasma kallikrein inhibitor drug candidate in clinical development for the on-demand treatment of hereditary angioedema (HAE). Upon binding, sebetralstat induces a conformational change in the active site of plasma kallikrein, which contributes to its high potency (Ki 3 nM) and selectivity (>1500 fold) against other serine proteases. Its physiochemical properties promote both rapid dissolution in the stomach and rapid absorption in the upper intestine that contribute to its fast and efficient absorption. A single oral administration of sebetralstat rapidly provides near-complete inhibition of plasma kallikrein and blockade of high-molecular-weight kininogen cleavage as early as 15 min, which drives its clinical efficacy. In a phase 2 clinical trial, sebetralstat significantly reduced the time to beginning of symptom relief (p < 0.0001) with median times of 1.6 h (95% CI: 1.5–3.0) with sebetralstat versus 9.0 h (4.0–17.2) with placebo. KONFIDENT (NCT05259917) is a phase 3 clinical trial assessing the on-demand use of sebetralstat for HAE. If successful, this trial could support the approval of sebetralstat as the first noninvasive, on-demand treatment option to rapidly halt HAE attacks and provide fast symptom relief.

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.

Initiation of the bradykinin generation cascade is responsible for the occurrence of attacks in some types of angioedema without wheals. Hereditary angioedema due to C1 inhibitor deficiency (HAE-C1-INH) is one such clinical entity. In this paper, we explore the existing evidence that mast cells (MCs) degranulation may contribute to the activation of the kallikrein-kinin system cascade, followed by bradykinin formation and angioedema. We present the multidirectional effects of MC-derived heparin and other polyanions on the major components of the kinin-kallikrein system, particularly on the factor XII activation. Although, bradykinin- and histamine-mediated symptoms are distinct clinical phenomena, they share some common features, such as some similar triggers and a predilection to occur at sites where mast cells reside, namely the skin and mucous membranes. In addition, recent observations indicate a high incidence of hypersensitivity reactions associated with MC degranulation in the HAE-C1-INH patient population. However, not all of these can be explained by IgE-dependent mechanisms. Mast cell-related G protein-coupled receptor-X2 (MRGPRX2), which has recently attracted scientific interest, may be involved in the activation of MCs through a different pathway. Therefore, we reviewed MRGPRX2 ligands that HAE-C1-INH patients may be exposed to in their daily lives and that may affect MCs degranulation. We also discussed the known inter-and intra-individual variability in the course of HAE-C1-INH in relation to factors responsible for possible variability in the strength of the response to MRGPRX2 receptor stimulation. The above issues raise several questions for future research. It is not known to what extent a prophylactic or therapeutic intervention targeting the pathways of one mechanism (mast cell degranulation) may affect the other (bradykinin production), or whether the number of mast cells at a specific body site and their reactivity to triggers such as pressure, allergens or MRGPRX2 agonists may influence the occurrence of HAE-C1-INH attacks at that site. [ABSTRACT FROM AUTHOR]

Purpose: The retina contains a number of vasoactive neuropeptides and corresponding receptors, but the role of these neuropeptides for tone regulation of retinal arterioles has not been studied in detail. Methods: Porcine arterioles with preserved perivascular retinal tissue were mounted in a wire myograph, and the tone was measured after the addition of increasing concentrations of bradykinin, vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), substance P (SP), calcitonin gene‐related peptide (CGRP) and brain natriuretic peptide (BNP). The experiments were performed during inhibition of the synthesis of nitric oxide (NO), prostaglandins and dopamine and were repeated after removal of the perivascular retinal tissue. Results: Bradykinin, VIP and CGRP induced significant concentration‐dependent dilatation and NPY significant concentration‐dependent contraction of the arterioles in the presence of perivascular retinal tissue (p < 0.03 for all comparisons) but not on isolated arterioles. BNP and SP had no effect on vascular tone. The NOS inhibitor L‐NAME reduced bradykinin‐ and VIP‐induced relaxation (p < 0.001 for both comparisons), whereas none of the other inhibitors influenced the vasoactive effects of the studied neuropeptides. Conclusion: The effects of neuropeptides on the tone of retinal arterioles depend on the perivascular retinal tissue and may involve effects other than those mediated by nitric oxide, prostaglandins and adrenergic compounds. Investigation of the mechanisms underlying the vasoactive effect of neuropeptides may be important for understanding and treating retinal diseases where disturbances in retinal flow regulation are involved in the disease pathogenesis. [ABSTRACT FROM AUTHOR]

Angiotensin converting enzyme inhibitors (ACE-Is) prevent the breakdown of bradykinin and can lead to life threatening angioedema. Tranexamic acid is an antifibrinolytic that inhibits formation of precursors involved in bradykinin synthesis and, in case reports, has been described as a potential treatment for ACE-I angioedema. This retrospective study included patients who presented to the emergency department (ED) from January 2018 to August 2021 with angioedema while taking an ACE-I. Patients who received tranexamic acid (treatment group) were compared with patients who did not receive tranexamic acid (control group). Primary outcome was length of stay (LOS). Secondary outcomes evaluated included ICU admissions, intubations, and safety events. A total of 262 patients were included in this study (73 treatment; 189 control). Overall, the median ED LOS was longer in the treatment group than controls (20.9 h vs 4.8 h, p < 0.001). ICU admission rates were higher in the treatment group (45% vs 16%, p < 0.001). More patients were intubated in the treatment group (12% vs 3%, p = 0.018). No difference was seen between the treatment group and the controls for return within 7 days, complications related to thrombosis, and death. In patients presenting with severe angioedema symptoms who were admitted to the hospital, median LOS was not different between the two groups (58.7 h vs 55.7 h, p = 0.61). Patients who received tranexamic acid had increased ED LOS, rates of ICU admission, and need for intubation. This finding may be related to the severity of presentation. Administration of tranexamic acid appears safe to use in ACE-I angioedema. Prospective randomized controlled studies should be considered to determine whether tranexamic acid is an effective treatment for ACE-I angioedema. [ABSTRACT FROM AUTHOR]

The vasoactive peptide bradykinin (BK) is an important member of the renin–angiotensin system. Its discovery is tightly interwoven with snake venom research, because it was first detected in plasma following the addition of viper venom. While the fact that venoms liberate BK from a serum globulin fraction is well described, its destruction by the venom has largely gone unnoticed. Here, BK was found to be cleaved by snake venom metalloproteinases in the venom of Echis ocellatus, one of the deadliest snakes, which degraded its dabsylated form (DBK) in a few minutes after Pro7 (RPPGFSP↓FR). This is a common cleavage site for several mammalian proteases such as ACE, but is not typical for matrix metalloproteinases. Residual protease activity < 5% after addition of EDTA indicated that DBK is also cleaved by serine proteases to a minor extent. Mass spectrometry-based protein analysis provided spectral proof for several peptides of zinc metalloproteinase-disintegrin-like Eoc1, disintegrin EO4A, and three serine proteases in the venom. [ABSTRACT FROM AUTHOR]

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]

Introduction: Aerobic physical training (APT) reduces eosinophilic airway inflammation, but its effects and mechanisms in severe asthma remain unknown. Methods: An in vitro study employing key cells involved in the pathogenesis of severe asthma, such as freshly isolated human eosinophils, neutrophils, and bronchial epithelial cell lineage (BEAS-2B) and lung fibroblasts (MRC-5 cells), was conducted. Additionally, an in vivo study using male C57Bl/6 mice, including Control (Co; n = 10), Trained (Exe; n = 10), house dust mite (HDM; n = 10), and HDM + Trained (HDM + Exe; n = 10) groups, was carried out, with APT performed at moderate intensity, 5x/week, for 4 weeks. Results: HDM and bradykinin, either alone or in combination, induced hyperactivation in human neutrophils, eosinophils, BEAS-2B, and MRC-5 cells. In contrast, IL-10, the primary anti-inflammatory molecule released during APT, inhibited these inflammatory effects, as evidenced by the suppression of numerous cytokines and reduced mRNA expression of the B1 receptor and ACE-2. The in vivo study demonstrated that APT decreased bronchoalveolar lavage levels of bradykinin, IL-1β, IL-4, IL-5, IL-17, IL-33, TNF-α, and IL-13, while increasing levels of IL-10, klotho, and IL-1RA. APT reduced the accumulation of polymorphonuclear cells, lymphocytes, and macrophages in the peribronchial space, as well as collagen fiber accumulation, epithelial thickness, and mucus accumulation. Furthermore, APT lowered the expression of the B1 receptor and ACE-2 in lung tissue and reduced bradykinin levels in the lung tissue homogenate compared to the HDM group. It also improved airway resistance, tissue resistance, and tissue damping. On a systemic level, APT reduced total leukocytes, eosinophils, neutrophils, basophils, lymphocytes, and monocytes in the blood, as well as plasma levels of IL-1β, IL-4, IL-5, IL-17, TNF-α, and IL-33, while elevating the levels of IL-10 and IL-1RA. Conclusion: These findings indicate that APT inhibits the severe asthma phenotype by targeting kinin signaling. [ABSTRACT FROM AUTHOR]

Typical pathogenic bacteria of the genus Bordetella cause respiratory diseases, many of which are characterized by severe coughing in host animals. In human infections with these bacteria, such as whooping cough, coughing imposes a heavy burden on patients. The pathophysiology of this severe coughing had long been uncharacterized because convenient animal models that reproduce Bordetella‐induced cough have not been available. However, rat and mouse models were recently shown as useful for understanding, at least partially, the causative factors and the mechanism of Bordetella‐induced cough. Many types of coughs are induced under various physiological conditions, and the neurophysiological pathways of coughing are considered to vary among animal species, including humans. However, the neurophysiological mechanisms of the coughs in different animal species have not been entirely understood, and, accordingly, the current understanding of Bordetella‐induced cough is still incomplete. Nevertheless, recent research findings may open the way for the development of prophylaxis and therapeutic measures against Bordetella‐induced cough. [ABSTRACT FROM AUTHOR]

Hereditary angioedema (HAE) is a rare disease caused by a genetic alteration of the SERPING1 gene and characterized by recurrent attacks of angioedema that involve the skin, and the mucosae of the gastrointestinal tract and upper airways, which significantly affect the quality of life of patients. Nowadays there are effective drugs for both 1. treating acute attacks and 2. preventing attacks with a long-term prophylaxis. However, there are some unmet needs for HAE treatment, and therefore several novel molecules are under active testing for this clinical condition. Novel drugs will simplify the mode of administration (oral versus parenteral for both on demand treatment or long-term prophylaxis), prolong the interval between administrations (up to 3–6 months of efficacy with a single administration), target more specifically the central enzymes involved in the generation of bradykinin, the ultimate mediator of angioedema (prekallikrein, activated plasma kallikrein or activated factor XII), and potentially determine a definitive cure for the disease by genetic manipulation of the altered gene (SERPING1) or other downstream genes (KLKB1). In this review we provide a panoramic view of all new medications that are under active experimentation and will probably transform and enrich all of the therapeutic armamentarium for treating this disease. [ABSTRACT FROM AUTHOR]

Introduction: Although as of today, the hypothesis of bradykinin storm in COVID-19 cannot be directly confirmed, many theoretical assumptions and empirical data support its validity. Aim: The purpose of this article is, using the example of a clinical case, to draw attention to the need for further study of the pathogenesis and clinical manifestations of COVID-19 and post-COVID-19 syndrome, considering the assessment of various theories, including bradykinin storm hypothesis. Case study: We analysed the data from a young male patient with post-COVID-19 syndrome who referred to a consultant and expressed complaints of palpitation, blood pressure increase, muscle weakness, feeling of fear, hypochondria, sleep disturbances, and reduced working performance. Results and discussion: We found a high degree of autonomic dysregulation (predominantly sympathetic hyperactivation), anxiety, and sleep disorder. There was no hypertension, though ambulatory blood pressure monitoring allowed to determine the status of non-dipper. Patient's blood tests after COVID-19 revealed a decrease in the plasma level of aldosterone, a significant increase in both homocysteine blood level and free cortisol in urine, and mild transient isolated increase in free triiodothyronine. All abnormal blood test parameters turned to normal in 3 months after the onset of COVID-19. We assume that the clinical symptoms and changes in a number of laboratory parameters of the presented case may be associated with the effects of bradykinin storm. Conclusions: This clinical case suggests continuing the discussion about the potential role of bradykinin storm in the clinical course of COVID-19 and post-COVID-19 syndrome. [ABSTRACT FROM AUTHOR]

Angiotensin-converting enzyme (ACE) inhibitors are used primarily in the treatment of hypertension, heart failure, and in the acute phase of myocardial infarction. Lisinopril [N2-[(1S)-1-car-boxy-3-phenylpropyl]-L-lysyl-L-proline], enalapril [(S)-1-[N-[1-(ethoxycarbonyl)-3-phenylpropyl]-L-alanyl]-L-proline] and ramipril [2-aza-bicyclo-[3.3.0]-octane-3-carboxylic acid] are all five-membered heterocycles and three of the most prevalent ACE inhibitors in clinical use worldwide. ACE inhibitor-induced angioedema (AE) is clinically characterized by self-limited edema of the dermis and subcutaneous lipid tissue, localized on face skin, oral mucosa and tongue in most cases. However, severe episodes of intestinal AE misdiagnosed as acute appendicitis and laryngeal AE requiring incubation have been reported. The pathophysiology of ACE inhibitor-induced angioedema is attributed to the accumulation of bradykinin, which is a potent vasodilator with proinflammatory activity that is normally degraded by angiotensin-converting enzyme (ACE) and aminopeptidase P; however, a small proportion of treated patients is affected. Given that patients do not respond to anti-H1 antihistamines and steroids, early clinical recognition and discontinuation of the ACE inhibitors are the treatments of choice for the long-term management of ACE inhibitor- induced angioedema. The search period of the present review was set up until November 2023, and its aim is to shed light on the broader context of ACE inhibitor-induced angioedema, exploring aspects such as clinical presentation, pathophysiology, and therapeutic considerations in this potentially life-threatening condition. The exploration of alternative drug options such as angiotensin II receptor blockers, the potential association of coadministration of DPP-4 inhibitors with ACE inhibitors, the presentation of angioedema and the significant clinical importance of this condition are also discussed. By focusing on the chemical structure of ACE inhibitors, specifically their nitrogen-based heterocycles—an attribute shared by over 880 drugs approved by the FDA within the pharmaceutical industry—this review emphasizes the pivotal role of nitrogen scaffolds in drug design and underscores their relevance in ACE inhibitor pharmacology. [ABSTRACT FROM AUTHOR]

A bradykinin B1 receptors antagonist PAV-0056, an 1,4-benzodiazepin-2-one derivative, intragastrically administrated to mice at doses of 0.1 and 1 mg/kg causes analgesia in the "formalin test" not inferior to that of diclofenac sodium (10 mg/kg) and tramadol (20 mg/kg). PAV-0056 at doses of 0.1 and 10 mg/kg has no anxiolytic and central muscle relaxant effects in mice and does not damage the gastric mucosa in rats. Based on the results of the conditioned place preference test, PAV-0056 also does not induce addiction in mice. [ABSTRACT FROM AUTHOR]

Transient receptor potential vanilloid type‐1 (TRPV1) channels play key roles in chronic pain conditions and are modulated by different inflammatory mediators to elicit heat sensitisation. Bradykinin is a 9‐amino acid peptide chain that promotes inflammation. The aim of present study is to investigate how bradykinin and prostaglandin receptors (EP3 and EP4) modulate the sensitisation of TRPV1‐mediated responses. Calcium imaging studies of rat dorsal root ganglion (DRG) neurons were employed to investigate the desensitizing responses of TRPV1 ion channels by capsaicin, and the re‐sensitization of TRPV1 by bradykinin, then to explore the role EP3 and EP4 receptors in mediating these bradykinin‐dependent effects. Immunocytochemistry was used to study the co‐expression and distribution of EP4, TRPV1, COX‐1 and B2 in rat DRG neurons. Desensitization was seen upon repeated capsaicin application, we show that bradykinin‐mediated sensitization of capsaicin‐evoked calcium responses in rat DRG neurons occurs is dependent on COX‐1 activity and utilizes a pathway that involves EP4 but not EP3 receptors. Immunocytochemical techniques revealed that EP4, TRPV1, COX‐1 and B2 proteins are expressed mainly in small diameter (<1000 μm2) cell bodies of rat DRG neurons which are typically nociceptors. The present study provides suggestive evidence for a potential signalling pathway through which bradykinin may regulate TRPV1 ion channel function via EP4 receptors. In addition to confirming existing knowledge, the anatomical distribution and colocalization of these proteins in DRG neurons as revealed by this study offer valuable insight. [ABSTRACT FROM AUTHOR]

Hereditary angioedema (HAE) is a rare disease caused by a genetic alteration of the SERPING1 gene and characterized by recurrent attacks of angioedema that involve the skin, and the mucosae of the gastrointestinal tract and upper airways, which significantly affect the quality of life of patients. Nowadays there are effective drugs for both 1. treating acute attacks and 2. preventing attacks with a long-term prophylaxis. However, there are some unmet needs for HAE treatment, and therefore several novel molecules are under active testing for this clinical condition. Novel drugs will simplify the mode of administration (oral versus parenteral for both on demand treatment or long-term prophylaxis), prolong the interval between administrations (up to 3–6 months of efficacy with a single administration), target more specifically the central enzymes involved in the generation of bradykinin, the ultimate mediator of angioedema (prekallikrein, activated plasma kallikrein or activated factor XII), and potentially determine a definitive cure for the disease by genetic manipulation of the altered gene (SERPING1) or other downstream genes (KLKB1). In this review we provide a panoramic view of all new medications that are under active experimentation and will probably transform and enrich all of the therapeutic armamentarium for treating this disease.

Escin, extracted from horse chestnut (Aesculus hippocastanum) has anti-edema and anti-inflammatory effects. It is used to treat several clinical conditions, including venous insufficiency, pain, inflammation, and edema. Considering escin’s pharmacodynamic, the inhibition of the bradykinin pathway represents a particular effect, decreasing the local edema and conferring an advantage in comparison to other compounds. In this narrative review, we described the effects of escin considering its effects on bradykinin pathway.

Evidence suggests that angiotensin-converting enzyme inhibitors (ACEIs) may increase metabolic rate by promoting thermogenesis, potentially through enhanced fat oxidation and improved insulin. More research is, however, needed to understand this intricate process. In this study, we used 22 lines from the Drosophila Genetic Reference Panel to assess the metabolic rate of virgin female and male flies that were either fed a standard medium or received lisinopril for one week or five weeks. We demonstrated that lisinopril affects the whole-body metabolic rate in Drosophila melanogaster in a genotype-dependent manner. However, the effects of genotypes are highly context-dependent, being influenced by sex and age. Our findings also suggest that lisinopril may increase the Drosophila metabolic rate via the accumulation of a bradykinin-like peptide, which, in turn, enhances cold tolerance by upregulating Ucp4b and Ucp4c genes. Finally, we showed that knocking down Ance, the ortholog of mammalian ACE in Malpighian/renal tubules and the nervous system, leads to opposite changes in metabolic rate, and that the effect of lisinopril depends on Ance in these systems, but in a sex- and age-specific manner. In conclusion, our results regarding D. melanogaster support existing evidence of a connection between ACEI drugs and metabolic rate while offering new insights into this relationship.

Objective: Unusual clinical course. Background: Angioedema is non-pitting edema that occurs in the deep layers of the skin and subcutaneous tissue due to vascular leakage of plasma resulting from 1 of 2 major pathophysiological processes: mast cell-mediated angioedema and bradykinin-mediated angioedema. While it is a well-recognized adverse reaction of angiotensin-converting enzyme inhibitors, the association of angioedema with angiotensin receptor blockers is relatively less studied. Direct local trauma, although rarely, has been suggested to induce angioedema under certain conditions. We present a unique case of direct, local, trauma-related angioedema in a patient on an angiotensin receptor blocker. Case Report: The patient, an 83-year-old woman on telmisartan for hypertension, hit her neck against the edge of a chair during a fall. Shortly thereafter, she developed progressive airway compromise due to airway angioedema, as noted on direct laryngoscopy. A contrast CT scan of the neck also noted edema of the periglottic and supraglottic regions. She required intravenous corticosteroid administration and intubation in the emergency room and was successfully extubated 3 days after admission. She had no prior history of angioedema or allergy. We hypothesize that increased levels of circulatory bradykinin in the setting of telmisartan, combined with a local release of bradykinin from trauma, was the main pathophysiologic cause of the angioedema. Conclusions: This case report highlights the rare and often forgotten adverse reaction of angioedema with use of angiotensin receptor blockers and confirms the finding of local trauma as a possible trigger. [ABSTRACT FROM AUTHOR]

Microcirculatory and coagulation disturbances commonly occur as pathological manifestations of systemic viral infections. Research exploring the role of the kallikrein–kinin system (KKS) in flavivirus infections has recently linked microvascular dysfunctions to bradykinin (BK)-induced signaling of B2R, a G protein-coupled receptor (GPCR) constitutively expressed by endothelial cells. The relevance of KKS activation as an innate response to viral infections has gained increasing attention, particularly after the reports regarding thrombogenic events during COVID-19. BK receptor (B2R and B1R) signal transduction results in vascular permeability, edema formation, angiogenesis, and pain. Recent findings unveiling the role of KKS in viral pathogenesis include evidence of increased activation of KKS with elevated levels of BK and its metabolites in both intravascular and tissue milieu, as well as reports demonstrating that virus replication stimulates BKR expression. In this review, we will discuss the mechanisms triggered by virus replication and by virus-induced inflammatory responses that may stimulate KKS. We also explore how KKS activation and BK signaling may impact virus pathogenesis and further discuss the potential therapeutic application of BKR antagonists in the treatment of hemorrhagic and respiratory diseases. [ABSTRACT FROM AUTHOR]

The kallikrein–kinin system is a versatile regulatory network implicated in various biological processes encompassing inflammation, nociception, blood pressure control, and central nervous system functions. Its physiological impact is mediated through G-protein-coupled transmembrane receptors, specifically the B1 and B2 receptors. Dopamine, a key catecholamine neurotransmitter widely distributed in the CNS, plays a crucial role in diverse physiological functions including motricity, reward, anxiety, fear, feeding, sleep, and arousal. Notably, the potential physical interaction between bradykinin and dopaminergic receptors has been previously documented. In this study, we aimed to explore whether B2R modulation in catecholaminergic neurons influences the dopaminergic pathway, impacting behavioral, metabolic, and motor aspects in both male and female mice. B2R ablation in tyrosine hydroxylase cells reduced the body weight and lean mass without affecting body adiposity, substrate oxidation, locomotor activity, glucose tolerance, or insulin sensitivity in mice. Moreover, a B2R deficiency in TH cells did not alter anxiety levels, exercise performance, or motor coordination in female and male mice. The concentrations of monoamines and their metabolites in the substantia nigra and cortex region were not affected in knockout mice. In essence, B2R deletion in TH cells selectively influenced the body weight and composition, leaving the behavioral and motor aspects largely unaffected. [ABSTRACT FROM AUTHOR]

Simple Summary: Kinin receptors have been implicated in cancer migration, invasion, angiogenesis, and metastasis. However, research on the molecular changes that occur during glioma development remains incomplete. Therefore, we assessed differences in the expression of kinin receptors and kinin-dependent genes in forty-three patients with astrocytic gliomas of various tumor grades (G2, G3, and G4). In our study, we confirmed that kinins and their receptors are involved in the development of glioma. We also found genes whose expression change may have diagnostic and therapeutic significance. Kinins are a set of peptides present in tissues that are involved in the inflammatory response and cancer progression. However, studies showing the expression of kinin receptors in human glioma samples are still incomplete and contradictory. The aim of the present study was to ascertain the expression of BDKRB1 and BDKRB2 genes, as well as the level of B1R and B2R proteins in human gliomas, depending on the degree of malignancy. Additionally, representative kinin-dependent genes with altered expression were indicated. The expression profile of kinin-dependent genes was determined using oligonucleotide microarray technique. In addition, RT-qPCR was used to assess the expression level of selected differentiating genes. The location of kinin receptors in brain gliomas was assessed using immunohistochemical methods. The oligonucleotide microarray method was used to identify 12 mRNA IDs of kinin-related genes whose expression was upregulated or downregulated in gliomas of different grades. In immunohistochemically stained samples, the concentrations of BR1 and BR2 proteins, measured by optical density, were statistically significantly higher in grade G3 vs. G2 and G4 vs. G3. Increased expression of kinin receptors BDKRB1 and BDKRB2 in brain gliomas, depending on the degree of malignancy, suggests the involvement of kinins and their receptors in the disease's pathogenesis. Quantitative assessment of mRNA BDKRB1, PRKAR1A, MAP2K, and EGFR in patients with brain tumors may hold diagnostic and therapeutic significance. [ABSTRACT FROM AUTHOR]

Bradykinin is a peptide implicated in inflammatory pain in both humans and rodents. In rodent sensory neurons, activation of B1 and B2 bradykinin receptors induces neuronal hyperexcitability. Recent evidence suggests that human and rodent dorsal root ganglia (DRG), which contain the cell bodies of sensory neurons, differ in the expression and function of key GPCRs and ion channels; whether bradykinin receptor expression and function are conserved across species has not been studied in depth. In this study, we used human DRG tissue from organ donors to provide a detailed characterization of bradykinin receptor expression and bradykinin-induced changes in the excitability of human sensory neurons. We found that B2 and, to a lesser extent, B1 receptors are expressed by human DRG neurons and satellite glial cells. B2 receptors were enriched in the nociceptor subpopulation. Using patch-clamp electrophysiology, we found that acute bradykinin increases the excitability of human sensory neurons, whereas prolonged exposure to bradykinin decreases neuronal excitability in a subpopulation of human DRG neurons. Finally, our analyses suggest that donor's history of chronic pain and age may be predictors of higher B1 receptor expression in human DRG neurons. Together, these results indicate that acute bradykinin-induced hyperexcitability, first identified in rodents, is conserved in humans and provide further evidence supporting bradykinin signaling as a potential therapeutic target for treating pain in humans. [ABSTRACT FROM AUTHOR]

Moyamoya disease (MMD) is a rare disorder of the cerebrovascular system. It is a steno‐occlusive disease that involves angiogenesis and blood–brain barrier (BBB) disruption. Bradykinin (BK), its metabolite des‐Arg9‐BK, and receptor (B1R) affect angiogenesis and BBB integrity. In this study, we aimed to investigate the changes in BK, B1R and des‐Arg9‐BK levels in the serum and brain tissues of patients with MMD and explore the underlying mechanism of these markers in MMD. We obtained the serum samples and superficial temporal artery (STA) tissue of patients with MMD from the Department of Neurosurgery of the Jining First People's Hospital. First, we measured BK, des‐Arg9‐BK and B1R levels in the serum of patients by means of ELISA. Next, we performed immunofluorescence to determine B1R expression in STA tissues. Finally, we determined the underlying mechanism through Western blot, angiogenesis assay, immunofluorescence, transendothelial electrical resistance and transcytosis assays. Our results demonstrated a significant increase in the BK, des‐Arg9‐BK and B1R levels in the serum of patients with MMD compared to healthy controls. Furthermore, an increase in the B1R expression level was observed in the STA tissues of patients with MMD. BK and des‐Arg9‐BK could promote the migratory and proliferative abilities of bEnd.3 cells and inhibited the formation of bEnd.3 cell tubes. In vitro BBB model showed that BK and des‐Arg9‐BK could reduce claudin‐5, ZO‐1 and occluding expression and BBB disruption. To the best of our knowledge, our results show an increase in BK and B1R levels in the serum and STA tissues of patients with MMD. BK and Des‐Arg9‐BK could inhibit angiogenesis, promote migratory and proliferative capacities of cells, and disrupt BBB integrity. Therefore, regulating BK, des‐Arg9‐BK and B1R levels in the serum and the brain could be potential strategies for treating patients with MMD. [ABSTRACT FROM AUTHOR]

Simple Summary: Snakes are reptiles that have evolved over a period of approximately 170 million years, adapting to life in different habitats, including water (rivers and oceans), on the ground, in trees, and underground. The distance from the heart to the brain is known to be shorter in arboreal snakes compared to terrestrial ones, indicating that differences in habitat may also affect vascular response. In this study, we attempted to characterize vasoreactivity in the Tokara habu, a semi-arboreal snake. The Tokara habu snakes demonstrated a number of relaxation responses to various vasoactive substances, and they showed complex vasoreactivity, a contrast to the simple vasoreactivity seen in terrestrial snakes. These results suggest that the Tokara habu's distinctive, complex vasoreactivity may reflect adaptation to its semi-arboreal environment. Comparisons of vascular responses may be useful as a new approach to behavioral and ecological studies for species that are difficult to observe in the field. Vasoreactivity is relatively well documented in terrestrial snakes but has previously been investigated in only one semi-arboreal snake species. Consequently, the extent to which vasoreactivity is common across snake taxa or varies by habitat is unclear. The Tokara habu (Protobothrops tokarensis) is a semi-arboreal snake endemic to only two small adjacent Japanese islands, and hence a useful species for further investigation of vasoreactivity. We evaluated responses to known vasoactive substances in thoracic aortas isolated from Tokara habu. Under resting tension, noradrenaline and angiotensin II induced concentration-dependent contraction, but acetylcholine, serotonin (5-hydroxytriptamine; 5-HT), and isoproterenol induced relaxation followed by contraction. Histamine and rattlesnake bradykinin had no effect. Experiments with receptor-specific antagonists suggest that M1 and M3 receptors are involved in the acetylcholine-induced response; 5-HT1, 5-HT2, and 5-HT7 receptors in the serotonin-induced response; and β1 and β2 adrenoceptors in isoproterenol-induced relaxation. This is the first report on such response patterns in snakes (including serotonin- and isoproterenol-induced relaxation). Nitric oxide may be involved in acetylcholine-induced relaxation but not in the responses to serotonin or isoproterenol. In contrast to the uniform vasoreactivity observed in terrestrial snakes, the vasoreactivity of semi-arboreal snakes may be governed by diverse regulatory mechanisms. [ABSTRACT FROM AUTHOR]

Bradykinin (BK) has been recognized as a stimulant for matrix metalloproteinase (MMP)-9 expression, contributing to neuroinflammation. Modulating the BK/MMP-9 pathway offers potential in the treatment of neuroinflammatory disorders. Rhamnetin (RNT), a flavonoid compound known for its antioxidant and anti-inflammatory effects, has shown promise. However, the specific mechanisms through which RNT inhibits BK-induced MMP-9 expression remain unclear. Therefore, this study aims to delve into the intricate mechanisms underlying this process. Here, we initially demonstrated that RNT effectively attenuated BK-induced MMP-9 expression and its associated cell migration in rat brain astrocyte-1 (RBA-1) cells. Further investigation revealed that BK-driven MMP-9 protein, mRNA, and promoter activity linked to cell migration relied on c-Src, Pyk2, EGFR, PDGFR, PI3K/Akt, JNK1/2, and c-Jun. This was validated by the inhibition of these effects through specific inhibitors, a finding substantiated by the introduction of siRNAs targeting these signaling molecules. Notably, the phosphorylated levels of these signaling components induced by BK were significantly reduced by their respective inhibitors and RNT, underscoring the inhibitory role of RNT in this process. These findings indicate that, in RBA-1 cells, RNT diminishes the heightened induction of MMP-9 triggered by BK through the inhibition of c-Src/Pyk2/PDGFR and EGFR/PI3K/Akt/JNK1/2-dependent AP-1 activation. This suggests that RNT holds promise as a potential therapeutic approach for addressing neuroinflammation in the brain. [ABSTRACT FROM AUTHOR]