Mast cell degranulation and bradykinin-induced angioedema - searching for the missing link.

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.

Analgesic and Psychotropic Effects of a New Bradykinin Antagonist.

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.

An Overview of Hereditary Angioedema for the Primary Care Physician.

Hereditary angioedema is a rare autosomal dominant condition characterized by episodes of swelling of the upper airway, intestines, and skin. The disorder is characterized by deficiency in C1 esterase inhibitor (C1-INH) or a decrease in functional C1-INH. Treatment options include on demand therapy (treatment of acute attacks), long-term prophylaxis, and short-term prophylaxis. Corticosteroids, epinephrine, and antihistamines are not effective for this form of angioedema. The high mortality in patients undiagnosed underscores a need for broader physician awareness to identify these patients and initiate therapy.

Increased Prolylcarboxypeptidase Expression Can Serve as a Biomarker of Senescence in Culture.

Prolylcarboxypeptidase (PRCP, PCP, Lysosomal Pro-X-carboxypeptidase, Angiotensinase C) controls angiotensin- and kinin-induced cell signaling. Elevation of PRCP appears to be activated in chronic inflammatory diseases [cardiovascular disease (CVD), diabetes] in proportion to severity. Vascular endothelial cell senescence and mitochondrial dysfunction have consistently been shown in models of CVD in aging. Cellular senescence, a driver of age-related dysfunction, can differentially alter the expression of lysosomal enzymes due to lysosomal membrane permeability. There is a lack of data demonstrating the effect of age-related dysfunction on the expression and function of PRCP. To explore the changes in PRCP, the PRCP-dependent prekallikrein (PK) pathway was characterized in early- and late-passage human pulmonary artery endothelial cells (HPAECs). Detailed kinetic analysis of cells treated with high molecular weight kininogen (HK), a precursor of bradykinin (BK), and PK revealed a mechanism by which senescent HPAECs activate the generation of kallikrein upon the assembly of the HK-PK complex on HPAECs in parallel with an upregulation of PRCP and endothelial nitric oxide (NO) synthase (eNOS) and NO formation. The NO production and expression of both PRCP and eNOS increased in early-passage HPAECs and decreased in late-passage HPAECs. Low activity of PRCP in late-passage HPAECs was associated with rapid decreased telomerase reverse transcriptase mRNA levels. We also found that, with an increase in the passage number of HPAECs, reduced PRCP altered the respiration rate. These results indicated that aging dysregulates PRCP protein expression, and further studies will shed light into the complexity of the PRCP-dependent signaling pathway in aging.

Cellular localization and seasonal variation of GnRH and Bradykinin in the ovary of Heteropneustes fossilis (Bloch.) during its reproductive cycle.

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 B2-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.

Bradykinin protects nucleus pulposus cells from tert-butyl hydroperoxide-induced damage and delays intervertebral disc degeneration.

Intervertebral disc degeneration (IVDD) is a leading cause of degenerative spinal disorders, involving complex biological processes. This study investigates the role of the kallikrein-kinin system (KKS) in IVDD, focusing on the protective effects of bradykinin (BK) on nucleus pulposus cells (NPCs) under oxidative stress. Clinical specimens were collected, and experiments were conducted using human and rat primary NPCs to elucidate BK's impact on tert-butyl hydroperoxide (TBHP)-induced oxidative stress and damage. The results demonstrate that BK significantly inhibits TBHP-induced NPC apoptosis and restores mitochondrial function. Further analysis reveals that this protective effect is mediated through the BK receptor 2 (B2R) and its downstream PI3K/AKT pathway. Additionally, BK/PLGA sustained-release microspheres were developed and validated in a rat model, highlighting their potential therapeutic efficacy for IVDD. Overall, this study sheds light on the crucial role of the KKS in IVDD pathogenesis and suggests targeting the B2R as a promising therapeutic strategy to delay IVDD progression and promote disc regeneration.

Inhibitory mechanisms of docosahexaenoic acid on carbachol-, angiotensin II-, and bradykinin-induced contractions in guinea pig gastric fundus smooth muscle.

We studied the inhibitory actions of docosahexaenoic acid (DHA) on the contractions induced by carbachol (CCh), angiotensin II (Ang II), and bradykinin (BK) in guinea pig (GP) gastric fundus smooth muscle (GFSM), particularly focusing on the possible inhibition of store-operated Ca2+ channels (SOCCs). DHA significantly suppressed the contractions induced by CCh, Ang II, and BK; the inhibition of BK-induced contractions was the strongest. Although all contractions were greatly dependent on external Ca2+, more than 80% of BK-induced contractions remained even in the presence of verapamil, a voltage-dependent Ca2+ channel inhibitor. BK-induced contractions in the presence of verapamil were not suppressed by LOE-908 (a receptor-operated Ca2+ channel (ROCC) inhibitor) but were suppressed by SKF-96365 (an SOCC and ROCC inhibitor). BK-induced contractions in the presence of verapamil plus LOE-908 were strongly inhibited by DHA. Furthermore, DHA inhibited GFSM contractions induced by cyclopiazonic acid (CPA) in the presence of verapamil plus LOE-908 and inhibited the intracellular Ca2+ increase due to Ca2+ addition in CPA-treated 293T cells. These findings indicate that Ca2+ influx through SOCCs plays a crucial role in BK-induced contraction in GP GFSM and that this inhibition by DHA is a new mechanism by which this fatty acid inhibits GFSM contractions.

Effects of intrarenal pelvic infusion of tumour necrosis factor-α and interleukin 1-ß on reno-renal reflexes in anaesthetised rats.

OBJECTIVE: Reno-renal reflexes are disturbed in cardiovascular and hypertensive conditions when elevated levels of pro-inflammatory mediators/cytokines are present within the kidney. We hypothesised that exogenously administered inflammatory cytokines tumour necrosis factor alpha (TNF-α) and interleukin (IL)-1ß modulate the renal sympatho-excitatory response to chemical stimulation of renal pelvic sensory nerves. METHODS: In anaesthetised rats, intrarenal pelvic infusions of vehicle [0.9% sodium chloride (NaCl)], TNF-α (500 and 1000 ng/kg) and IL-1ß (1000 ng/kg) were maintained for 30 min before chemical activation of renal pelvic sensory receptors was performed using randomized intrarenal pelvic infusions of hypertonic NaCl, potassium chloride (KCl), bradykinin, adenosine and capsaicin. RESULTS: The increase in renal sympathetic nerve activity (RSNA) in response to intrarenal pelvic hypertonic NaCl was enhanced during intrapelvic TNF-α (1000 ng/kg) and IL-1ß infusions by almost 800% above vehicle with minimal changes in mean arterial pressure (MAP) and heart rate (HR). Similarly, the RSNA response to intrarenal pelvic adenosine in the presence of TNF-α (500 ng/kg), but not IL-1ß, was almost 200% above vehicle but neither MAP nor HR were changed. There was a blunted sympatho-excitatory response to intrapelvic bradykinin in the presence of TNF-α (1000 ng/kg), but not IL-1ß, by almost 80% below vehicle, again without effect on either MAP or HR. CONCLUSION: The renal sympatho-excitatory response to renal pelvic chemoreceptor stimulation is modulated by exogenous TNF-α and IL-1ß. This suggests that inflammatory mediators within the kidney can play a significant role in modulating the renal afferent nerve-mediated sympatho-excitatory response.

Aerobic physical training reduces severe asthma phenotype involving kinins pathway.

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-1ß, 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-1ß, 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.

Pulsed Direct Current Arc-Induced Nanoelectrospray Ionization Mass Spectrometry.

This study explores the innovative field of pulsed direct current arc-induced nanoelectrospray ionization mass spectrometry (DCAI-nano-ESI-MS), which utilizes a low-temperature direct current (DC) arc to induce ESI during MS analyses. By employing a 15 kV output voltage, the DCAI-nano-ESI source effectively identifies various biological molecules, including angiotensin II, bradykinin, cytochrome C, and soybean lecithin, showcasing impressive analyte signals and facilitating multicharge MS in positive- and negative-ion modes. Notably, results show that the oxidation of fatty acids using a DC arc produces [M + O - H]- ions, which aid in identifying the location of C═C bonds in unsaturated fatty acids and distinguishing between isomers based on diagnostic ions observed during collision-induced dissociation tandem MS. This study presents an approach for identifying the sn-1 and sn-2 positions in phosphatidylcholine using phosphatidylcholine and nitrate adduct ions, accurately determining phosphatidylcholine molecular configurations via the Paternò-Büchi reaction. With all the advantages above, DCAI-nano-ESI holds significant promise for future analytical and bioanalytical applications.

Bradykinin attenuates endothelial-mesenchymal transition following cardiac ischemia-reperfusion injury.

AIMS: Endothelial-mesenchymal transition (EndMT) is a crucial pathological process contributing to cardiac fibrosis. Bradykinin has been found to protect the heart against fibrosis. Whether bradykinin regulates EndMT has not been determined. MATERIALS AND METHODS: Rats were subjected to ligation of the left anterior descending coronary artery for 1 h and subsequent reperfusion to induce cardiac ischemia-reperfusion (IR) injury. Bradykinin (0.5 µg/h) was infused by an osmotic pump implanted subcutaneously at the onset of reperfusion. Fourteen days later, the functional, histological, and molecular analyses were performed to investigate the changes in cardiac fibrosis and EndMT. Human coronary artery endothelial cells were utilized to determine the molecular mechanisms in vitro. RESULTS: Bradykinin treatment improved cardiac function and decreased fibrosis following cardiac IR injury, accompanied by ameliorated EndMT and increased nitric oxide (NO) production. In vitro experiments found that bradykinin mitigated transforming growth factor ß1 (TGFß1)-induced EndMT. Significantly, the bradykinin B2 receptor antagonist or endothelial nitric oxide synthase inhibitor abolished the effects of bradykinin on EndMT inhibition, indicating that the bradykinin B2 receptor and NO might mediate the effects of bradykinin on EndMT inhibition. CONCLUSION: Bradykinin plays an essential role in the process of cardiac fibrosis. Bradykinin preserves the cellular signature of endothelial cells, preventing them from EndMT following cardiac IR injury, possibly mediated by bradykinin B2 receptor activation and NO production.

Comprehensive Analysis of Coupled Proline Cis-Trans States in Bradykinin Using ωBP-REMD Simulations.

It is well-known that proline (Pro) cis-trans isomerization plays a decisive role in the folding and stabilization of proteins. The conformational coupling between isomerization states of different Pro residues in proteins during conformational adaptation processes is not well understood. In the present work, we investigate the coupled cis-trans isomerization of three Pro residues using bradykinin (BK), a partially unstructured nonapeptide hormone, as a model system. We use a recently developed enhanced-sampling molecular dynamics method (ω-bias potential replica exchange molecular dynamics; ωBP-REMD) that allows us to exhaustively sample all combinations of Pro isomer states and obtain converged probability densities of all eight state combinations within 885 ns ωBP-REMD simulations. In agreement with experiment, the all-trans state is seen to be the preferred isomer of zwitterionic aqueous BK. In about a third of its structures, this state presents the characteristic C-terminal ß-turn conformation; however, other isomer combinations also contribute significantly to the structural ensemble. Unbiased probabilities can be projected onto the peptide bond dihedral angles of the three Pro residues. This unveils the interdependence of the individual Pro isomerization states, i.e., a possible coupling of the different Pro isomers. The cis/trans equilibrium of a Pro residue can change by up to 2.5 kcal·mol-1, depending on the isomerization state of other Pro residues. For example, for Pro7, the simulations indicate that its cis state becomes favored compared to its trans state when Pro2 is switched from the trans state to the cis state. Our findings demonstrate the efficiency of the ωBP-REMD methodology and suggest that the coupling of Pro isomerization states may play an even more decisive role in larger folded proteins subject to more conformational restraints.

The contribution of the WNT pathway to the therapeutic effects of montelukast in experimental murine airway inflammation induced by ovalbumin and lipopolysaccharide.

The wingless/integrase-1 (WNT) pathway involved in the pathogenesis of inflammatory airway diseases has recently generated considerable research interest. Montelukast, a leukotriene receptor antagonist, provides therapeutic benefits in allergic asthma involving eosinophils. We aimed to investigate the role of the WNT pathway in the therapeutic actions of montelukast (MT) in a mixed type of allergic-acute airway inflammation model induced by ovalbumin (OVA) and lipopolysaccharide (LPS) in mice. Female mice were sensitized with intraperitoneal OVA-Al(OH)3 administration in the initiation phase and intranasal OVA followed by LPS administration in the challenge phase. The mice were divided into eight groups: control, asthmatic, and control/asthmatic treated with XAV939 (inhibitor of the canonical WNT pathway), LGK-974 (inhibitor of the secretion of WNT ligands), or MT at different doses. The inhibition of the WNT pathway prevented tracheal 5-HT and bradykinin hyperreactivity, while only the inhibition of the canonical WNT pathway partially reduced 5-HT and bradykinin contractions compared to the inflammation group. Therefore, MT treatment hindered 5-HT and bradykinin hyperreactivity associated with airway inflammation. Furthermore, MT prevented the increases in the phosphorylated GSK-3ß and WNT5A levels, which had been induced by airway inflammation, in a dose-dependent manner. Conversely, the MT application caused a further increase in the fibronectin levels, while there was no significant alteration in the phosphorylation of the Smad-2 levels in the isolated lungs of the mice. The MT treatment reversed the increase in the mRNA expression levels of interleukin-17A. An increase in eosinophil and neutrophil counts was observed in bronchoalveolar lavage fluid samples obtained from the mice in the inflammation group, which was hampered by the MT treatment. The inhibition of the WNT pathway did not alter inflammatory cytokine expression or cell infiltration. The WNT pathway mediated the therapeutic effects of MT due to the inhibition of GSK-3ß phosphorylation as well as the reduction of WNT5A levels in a murine airway inflammation model.

Chemical modification of bradykinin-polymer conjugates for optimum delivery of nanomedicines to tumors.

We recently prepared pH-responsive HPMA copolymer conjugates of bradykinin (P-BK), which release BK in response to the acidic tumor microenvironment, and found that administration of P-BK increased the tumor accumulation and therapeutic efficacy of nanomedicine. Because the release of BK from P-BK determines its onset of action, P-BKs with different release rates were prepared, and their properties were evaluated. The release kinetics were significantly altered by substitution proximal to hydrazone bond, release constant of methyl-substituted P-BK (P-MeBK) was approximately 4- and 80-fold higher than that of cyclopropyl-substituted P-BK (P-CPBK) and phenyl-substituted P-BK (P-PhBK). None of the P-BKs were active, but the release of BK restored their BK-like activity. Pre-administration of the P-BKs increased the tumor accumulation of nanomedicine in C26 tumor-bearing mice by 2- and 1.4-fold for P-MeBK and P-PhBK at 3 and 6 h. Altogether, this study provides insights into the design of pH-responsive nanodrugs with the desired release properties to target acidic lesions such as cancer and inflammation.

Maximakinin reversed H2O2 induced oxidative damage in rat cardiac H9c2 cells through AMPK/Akt and AMPK/ERK1/2 signaling pathways.

Maximakinin (MK), a homolog of bradykinin (BK), is extracted from skin venom of the Chinese toad Bombina maxima. Although MK has a good antihypertensive effect, its effect on myocardial cells is unclear. This study investigates the protective effect of MK on hydrogen peroxide (H2O2)-induced oxidative damage in rat cardiac H9c2 cells and explores its mechanism of action. A 3-(4,5-Dimethyl-2-Thiazolyl)-2,5-Diphenyl Tetrazolium Bromide (MTT) assay was selected to detect the effect of MK on H9c2 cell viability, while flow cytometry was used to investigate the influence of MK and H2O2 on intracellular reactive oxygen species (ROS) levels. Protein expression changes were detected by western blot. In addition, specific protein inhibitors were applied to confirm the induction of ROS-related signaling pathways by MK. MTT assay results show that MK significantly reversed H2O2-induced cell growth inhibition. Flow cytometry Dichlorodihydrofluorescein diacetate (DCFH-DA) staining shows that MK significantly reversed H2O2-induced increases in intracellular ROS production in H9c2 cells. Moreover, the addition of specific protein inhibitors suggests that MK reverses H2O2-induced oxidative damage by activating AMP-activated protein kinase (AMPK)/protein kinase B (Akt) and AMPK/extracellular-regulated kinase 1/2 (ERK1/2) pathways. Finally, an inhibitor of bradykinin B2 receptors (B2Rs), HOE-140, was applied to investigate potential targets of MK in H9c2 cells. HOE-140 significantly blocked induction of AMPK/Akt and AMPK/ERK1/2 pathways by MK, suggesting a potentially important role for B2Rs in MK reversing H2O2-induced oxidative damage. Above all, MK protects against oxidative damage by inhibiting H2O2-induced ROS production in H9c2 cells. The protective mechanism of MK may be achieved by activation of B2Rs to activate downstream AMPK/Akt and AMPK/ERK1/2 pathways.

Structural Characterization and Rat Aortic Vascular Reactivity of Bradykinin-Potentiating Peptides (BPPs) from the Snake Venom of Bothrops moojeni from Delta do Parnaíba Region, Brazil.

Snake venoms contain various bradykinin-potentiating peptides (BPPs). First studied for their vasorelaxant properties due to angiotensin converting enzyme (ACE) inhibition, these molecules present a range of binding partners, among them the argininosuccinate synthase (AsS) enzyme. This has renewed interest in their characterization from biological sources and the evaluation of their pharmacological activities. In the present work, the low molecular weight fraction of Bothrops moojeni venom was obtained and BPPs were characterized by mass spectrometry. Eleven BPPs or related peptides were sequenced, and one of them, BPP-Bm01, was new. Interestingly, some oxidized BPPs were detected. The three most abundant peptides were BPP-Bm01, BPP-Bax12, and BPP-13a, and their putative interactions with the AsS enzyme were investigated in silico. A binding cavity for these molecules was predicted, and docking studies allowed their ranking. Three peptides were synthesized and submitted to vasorelaxation assays using rat aortic rings. While all BPPs were active, BPP-Bm01 showed the highest potency in this assay. This work adds further diversity to BPPs from snake venoms and suggests, for the first time, a putative binding pocket for these molecules in the AsS enzyme. This can guide the design of new and more potent AsS activators.

Meta-analysis of ACE inhibitor-induced angioedema identifies novel risk locus.

BACKGROUND: Angioedema is a rare but potentially life-threatening adverse drug reaction in patients receiving angiotensin-converting enzyme inhibitors (ACEis). Research suggests that susceptibility to ACEi-induced angioedema (ACEi-AE) involves both genetic and nongenetic risk factors. Genome- and exome-wide studies of ACEi-AE have identified the first genetic risk loci. However, understanding of the underlying pathophysiology remains limited. OBJECTIVE: We sought to identify further genetic factors of ACEi-AE to eventually gain a deeper understanding of its pathophysiology. METHODS: By combining data from 8 cohorts, a genome-wide association study meta-analysis was performed in more than 1000 European patients with ACEi-AE. Secondary bioinformatic analyses were conducted to fine-map associated loci, identify relevant genes and pathways, and assess the genetic overlap between ACEi-AE and other traits. Finally, an exploratory cross-ancestry analysis was performed to assess shared genetic factors in European and African-American patients with ACEi-AE. RESULTS: Three genome-wide significant risk loci were identified. One of these, located on chromosome 20q11.22, has not been implicated previously in ACEi-AE. Integrative secondary analyses highlighted previously reported genes (BDKRB2 [bradykinin receptor B2] and F5 [coagulation factor 5]) as well as biologically plausible novel candidate genes (PROCR [protein C receptor] and EDEM2 [endoplasmic reticulum degradation enhancing alpha-mannosidase like protein 2]). Lead variants at the risk loci were found with similar effect sizes and directions in an African-American cohort. CONCLUSIONS: The present results contributed to a deeper understanding of the pathophysiology of ACEi-AE by (1) providing further evidence for the involvement of bradykinin signaling and coagulation pathways and (2) suggesting, for the first time, the involvement of the fibrinolysis pathway in this adverse drug reaction. An exploratory cross-ancestry comparison implicated the relevance of the associated risk loci across diverse ancestries.

Characterization of two distinct immortalized endothelial cell lines, EA.hy926 and HMEC-1, for in vitro studies: exploring the impact of calcium electroporation, Ca2+ signaling and transcriptomic profiles.

BACKGROUND: Disruption of Ca2+ homeostasis after calcium electroporation (CaEP) in tumors has been shown to elicit an enhanced antitumor effect with varying impacts on healthy tissue, such as endothelium. Therefore, our study aimed to determine differences in Ca2+ kinetics and gene expression involved in the regulation of Ca2+ signaling and homeostasis, as well as effects of CaEP on cytoskeleton and adherens junctions of the established endothelial cell lines EA.hy926 and HMEC-1. METHODS: CaEP was performed on EA.hy926 and HMEC-1 cells with increasing Ca2+ concentrations. Viability after CaEP was assessed using Presto Blue, while the effect on cytoskeleton and adherens junctions was evaluated via immunofluorescence staining (F-actin, α-tubulin, VE-cadherin). Differences in intracellular Ca2+ regulation ([Ca2+]i) were determined with spectrofluorometric measurements using Fura-2-AM, exposing cells to DPBS, ionomycin, thapsigargin, ATP, bradykinin, angiotensin II, acetylcholine, LaCl3, and GdCl3. Molecular distinctions were identified by analyzing differentially expressed genes and pathways related to the cytoskeleton and Ca2+ signaling through RNA sequencing. RESULTS: EA.hy926 cells, at increasing Ca2+ concentrations, displayed higher CaEP susceptibility and lower survival than HMEC-1. Immunofluorescence confirmed CaEP-induced, time- and Ca2+-dependent morphological changes in EA.hy926's actin filaments, microtubules, and cell-cell junctions. Spectrofluorometric Ca2+ kinetics showed higher amplitudes in Ca2+ responses in EA.hy926 exposed to buffer, G protein coupled receptor agonists, bradykinin, and angiotensin II compared to HMEC-1. HMEC-1 exhibited significantly higher [Ca2+]i changes after ionomycin exposure, while responses to thapsigargin, ATP, and acetylcholine were similar in both cell lines. ATP without extracellular Ca2+ ions induced a significantly higher [Ca2+]i rise in EA.hy926, suggesting purinergic ionotropic P2X and metabotropic P2Y receptor activation. RNA-sequencing analysis showed significant differences in cytoskeleton- and Ca2+-related gene expression, highlighting upregulation of ORAI2, TRPC1, TRPM2, CNGA3, TRPM6, and downregulation of TRPV4 and TRPC4 in EA.hy926 versus HMEC-1. Moreover, KEGG analysis showed upregulated Ca2+ import and downregulated export genes in EA.hy926. CONCLUSIONS: Our finding show that significant differences in CaEP response and [Ca2+]i regulation exist between EA.hy926 and HMEC-1, which may be attributed to distinct transcriptomic profiles. EA.hy926, compared to HMEC-1, displayed higher susceptibility and sensitivity to [Ca2+]i changes, which may be linked to overexpression of Ca2+-related genes and an inability to mitigate changes in [Ca2+]i. The study offers a bioinformatic basis for selecting EC models based on research objectives.

Tranexamic acid for angiotensin converting enzyme inhibitor induced angioedema: A retrospective multicenter study.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Potential Pathways and Pathophysiological Implications of Viral Infection-Driven Activation of Kallikrein-Kinin System (KKS).

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.