TRPV1 corneal neuralgia mutation: Enhanced pH response, bradykinin sensitization, and capsaicin desensitization.

The factors that contribute to pain after nerve injury remain incompletely understood. Laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) are common surgical techniques to correct refractive errors. After LASIK or PRK, a subset of patients suffers intense and persistent pain, of unknown origin, described by patients as feeling like shards of glass in their eye. Here, we evaluated a TRPV1 variant, p.V527M, found in a 49-y-old woman who developed corneal pain after LASIK and subsequent PRK enhancement, reporting an Ocular Surface Disease Index score of 100. Using patch-clamp and Ca2+ imaging, we found that the V527M mutation enhances the response to acidic pH. Increasing proton concentration induced a stronger leftward shift in the activation curve of V527M compared to WT, resulting in channel activity of the mutant in acidic pH at more physiological membrane potentials. Finally, comparing the responses to consecutive applications of different agonists, we found in V527M channels a reduced capsaicin-induced desensitization and increased sensitization by the arachidonic acid metabolite 12-hydroxyeicosatetraenoic acid (12-HETE). We hypothesize that the increased response in V527M channels to protons and enhanced sensitization by 12-HETE, two inflammatory mediators released in the cornea after tissue damage, may contribute to the pathogenesis of corneal neuralgia after refractive surgery.

A mechanism for hereditary angioedema caused by a methionine-379-to-lysine substitution in kininogens.

ABSTRACT: Hereditary angioedema (HAE) is associated with episodic kinin-induced swelling of the skin and mucosal membranes. Most patients with HAE have low plasma C1-inhibitor activity, leading to increased generation of the protease plasma kallikrein (PKa) and excessive release of the nanopeptide bradykinin from high-molecular-weight kininogen (HK). However, disease-causing mutations in at least 10% of patients with HAE appear to involve genes for proteins other than C1-inhibitor. A point mutation in the Kng1 gene encoding HK and low-molecular weight kininogen (LK) was identified recently in a family with HAE. The mutation changes a methionine (Met379) to lysine (Lys379) in both proteins. Met379 is adjacent to the Lys380-Arg381 cleavage site at the N-terminus of the bradykinin peptide. Recombinant wild-type (Met379) and variant (Lys379) versions of HK and LK were expressed in HEK293 cells. PKa-catalyzed kinin release from HK and LK was not affected by the Lys379 substitutions. However, kinin release from HK-Lys379 and LK-Lys379 catalyzed by the fibrinolytic protease plasmin was substantially greater than from wild-type HK-Met379 and LK-Met379. Increased kinin release was evident when fibrinolysis was induced in plasma containing HK-Lys379 or LK-Lys379 compared with plasma containing wild-type HK or LK. Mass spectrometry revealed that the kinin released from wild-type and variant kininogens by PKa is bradykinin. Plasmin also released bradykinin from wild-type kininogens but cleaved HK-Lys379 and LK-Lys379 after Lys379 rather than Lys380, releasing the decapeptide Lys-bradykinin (kallidin). The Met379Lys substitutions make HK and LK better plasmin substrates, reinforcing the relationship between fibrinolysis and kinin generation.

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.

Deucrictibant for angioedema due to acquired C1-inhibitor deficiency: A randomized-controlled trial.

BACKGROUND: Angioedema due to acquired C1-inhibitor deficiency is a very rare but serious disease, with an estimated prevalence of 1 per 500,000 persons. There are no approved therapies to treat or prevent angioedema swelling in patients with this condition. Deucrictibant is a specific, orally bioavailable, competitive antagonist of the bradykinin B2 receptor currently under investigation for hereditary angioedema. OBJECTIVE: Our aim was to assess the efficacy and safety of deucrictibant as acute and prophylactic treatment for angioedema due to acquired C1-inhibitor deficiency. METHODS: A 2-part, randomized, double-blind, placebo-controlled crossover study was conducted. In Part 1, 4 consecutive angioedema attacks were treated with 3 doses of deucrictibant (10 mg, 20 mg, and 30 mg) or placebo. In Part 2, deucricibant, 20 mg, or placebo was administered twice daily for 2 treatment periods of 8 weeks. RESULTS: Three patients were enrolled; of those 3 patients, 1 completed both study parts and 2 completed only Part 2. In Part 1, a reduction in attack severity was observed in the 3 attacks treated with deucrictibant as opposed to an increase in severity of the attack treated with placebo. In Part 2, the individual mean monthly attack rates were 2.0, 0.6, and 1.0 during the placebo period and 0.0 across all patients during treatment with deucrictibant. There were no severe adverse events and 1 self-limiting treatment-emergent adverse event (abdominal pain). CONCLUSIONS: Deucrictibant has the potential to effectively and safely treat and prevent angioedema attacks due to acquired C1-inhibitor deficiency.

Angioedema After Use of Recombinant Tissue-Type Plasminogen Activators in Stroke.

Angioedema without concomitant urticaria is a well-known complication of treatment with the recombinant tissue-type plasminogen activator (r-tPA) alteplase and its genetically modified variant tenecteplase. It is potentially lethal when causing airway obstruction and can require intubation. The latest guideline for the early management of patients with acute ischemic stroke from the American Heart Association/American Stroke Association advises to treat this complication initially by interfering with the histamine pathway. This article aims to clarify the pathophysiological mechanism of r-tPA-induced angioedema and provides several arguments that this condition is primarily bradykinin-mediated and hence should be treated initially by intervening with the bradykinin pathway. Second, other-less frequently reported-adverse symptoms after r-tPA therapy and their proposed pathophysiological mechanisms leading to specific treatment are described. This manuscript describes the need for an update of the section "3.5 IV alteplase" from the American Heart Association/American Stroke Association guideline to treat this r-tPA-induced angioedema adequately and prevent potentially fatal outcomes.

Intestinal barrier function in the naked mole-rat: an emergent model for gastrointestinal insights.

The intestinal barrier plays a crucial role in homeostasis by both facilitating the absorption of nutrients and fluids and providing a tight shield to prevent the invasion by either pathogen or commensal microorganisms. Intestinal barrier malfunction is associated with systemic inflammation, oxidative stress, and decreased insulin sensitivity, which may lead to the dysregulation of other tissues. Therefore, a deeper understanding of physiological aspects related to an enhanced barrier function is of significant scientific and clinical relevance. The naked mole-rat has many unusual biological features, including attenuated colonic neuron sensitivity to acid and bradykinin and resistance to chemical-induced intestinal damage. However, insight into their intestinal barrier physiology is scarce. Here, we observed notable macroscopic and microscopic differences in intestinal tissue structure between naked mole-rats and mice. Moreover, naked mole-rats showed increased number of larger goblet cells and elevated mucus content. In measuring gut permeability, naked mole-rats showed reduced permeability compared with mice, measured as transepithelial electrical resistance, especially in ileum. Furthermore, intestinal ion secretion induced by serotonin, bradykinin, histamine, and capsaicin was significantly reduced in naked mole-rats compared with mice, despite the expression of receptors for all these agonists. In addition, naked mole-rats exhibited reduced prosecretory responses to the nonselective adenylate cyclase activator forskolin. Collectively, these findings indicate that naked mole-rats possess a robust and hard-to-penetrate gastrointestinal barrier that is resistant to environmental and endogenous irritants. Naked mole-rats may therefore provide valuable insights into the physiology of the intestinal barrier and set the stage for the development of innovative and effective therapies.NEW & NOTEWORTHY This is the first study to characterize the intestinal function of naked mole-rats. We found that these animals show a robust gut tissue structure, displaying thicker intestinal layers, longer villi, and larger crypts. Naked mole-rats showed more and larger goblet cells, with increased mucus content. Intestinal permeability, especially in the ileum, was substantially lower than that of mice. Finally, naked mole-rats showed reduced intestinal anion secretion in response to serotonin, bradykinin, histamine, capsaicin, and forskolin.

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.

A mechanism for hereditary angioedema caused by a lysine 311-to-glutamic acid substitution in plasminogen.

Patients with hereditary angioedema (HAE) experience episodes of bradykinin (BK)-induced swelling of skin and mucosal membranes. The most common cause is reduced plasma activity of C1 inhibitor, the main regulator of the proteases plasma kallikrein (PKa) and factor XIIa (FXIIa). Recently, patients with HAE were described with a Lys311 to glutamic acid substitution in plasminogen (Plg), the zymogen of the protease plasmin (Plm). Adding tissue plasminogen activator to plasma containing Plg-Glu311 vs plasma containing wild-type Plg (Plg-Lys311) results in greater BK generation. Similar results were obtained in plasma lacking prekallikrein or FXII (the zymogens of PKa and FXIIa) and in normal plasma treated with a PKa inhibitor, indicating Plg-Glu311 induces BK generation independently of PKa and FXIIa. Plm-Glu311 cleaves high and low molecular weight kininogens (HK and LK, respectively), releasing BK more efficiently than Plm-Lys311. Based on the plasma concentrations of HK and LK, the latter may be the source of most of the BK generated by Plm-Glu311. The lysine analog ε-aminocaproic acid blocks Plm-catalyzed BK generation. The Glu311 substitution introduces a lysine-binding site into the Plg kringle 3 domain, perhaps altering binding to kininogens. Plg residue 311 is glutamic acid in most mammals. Glu311 in patients with HAE, therefore, represents reversion to the ancestral condition. Substantial BK generation occurs during Plm-Glu311 cleavage of human HK, but not mouse HK. Furthermore, mouse Plm, which has Glu311, did not liberate BK from human kininogens more rapidly than human Plg-Lys311. This indicates Glu311 is pathogenic in the context of human Plm when human kininogens are the substrates.

Kinin-kallikrein system: New perspectives in heart failure.

Heart failure (HF) is a pervasive clinical challenge characterized by compromised cardiac function and reduced quality of life. The kinin-kallikrein system (KSS), a multifaceted peptide cascade, has garnered substantial attention due to its potential role in HF. Through activation of B1 and/or B2 receptors and downstream signaling, kinins modulate various physiological processes, including inflammation, coagulation, pain, blood pressure control, and vascular permeability. Notably, aberrations in KKS components have been linked to HF risk. The elevation of vasodilatory bradykinin (BK) due to kallikrein activity reduces preload and afterload, while concurrently fostering sodium reabsorption inhibition. However, kallikrein's conversion of prorenin to renin leads to angiotensinsII upregulation, resulting in vasoconstriction and fluid retention, alongside increased immune cell activity that fuels inflammation and cardiac remodeling. Importantly, prolonged KKS activation resulting from volume overload and tissue stretch contributes to cardiac collagen loss. The conventional renin-angiotensin-aldosterone system (RAAS) inhibitors used in HF management may inadvertently intensify KKS activity, exacerbating collagen depletion and cardiac remodeling. It is crucial to balance the KKS's role in acute cardiac damage, which may temporarily enhance function and metabolic parameters against its detrimental long-term effects. Thus, KKS blockade emerges as a promising strategy to impede HF progression. By attenuating the link between immune system function and tissue damage, KKS inhibition can potentially reduce cardiac remodeling and alleviate HF symptoms. However, the nuanced roles of BK in various acute conditions necessitate further investigation into the sustained benefits of kallikrein inhibitors in patients with chronic HF.

Understanding COVID-19 outcome: Exploring the prognostic value of soluble biomarkers indicative of endothelial impairment.

Host proteins released by the activated endothelial cells during SARS-CoV-2 infection are implicated to be involved in coagulation and endothelial dysfunction. However, the underlying mechanism that governs the vascular dysfunction and disease severity in COVID-19 remains obscure. The study evaluated the serum levels of Bradykinin, Kallikrein, SERPIN A, and IL-18 in COVID-19 (N-42 with 20 moderate and 22 severe) patients compared to healthy controls (HC: N-10) using ELISA at the day of admission (DOA) and day 7 post-admission. The efficacy of the protein levels in predicting disease severity was further determined using machine learning models. The levels of bradykinins and SERPIN A were higher (P ≤ 0.001) in both severe and moderate cases on day 7 post-admission compared to DOA. All the soluble proteins studied were found to elevated (P ≤ 0.01) in severe compared to moderate in day 7 and were positively correlated (P ≤ 0.001) with D-dimer, a marker for coagulation. ROC analysis identified that SERPIN A, IL-18, and bradykinin could predict the clinical condition of COVID-19 with AUC values of 1, 0.979, and 1, respectively. Among the models trained using univariate model analysis, SERPIN A emerged as a strong prognostic biomarker for COVID-19 disease severity. The serum levels of SERPIN A in conjunction with the coagulation marker D-dimer, serve as a predictive indicator for COVID-19 clinical outcomes. However, studies are required to ascertain the role of these markers in disease virulence.

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.

Repeated doses of captopril induce airway hyperresponsiveness by modulating the TRPV1 receptor in rats.

Although TRPV1 receptors play an essential role in the adverse effects on the airways following captopril treatment, there is no available evidence of their involvement in treatment regimens involving repeated doses of captopril. Comparing the difference in these two treatment regimens is essential since captopril is a continuous-use medication. Thus, this study explored the role of the transient receptor potential vanilloid 1 (TRPV1) in the effects of captopril on rat airways using two treatment regimens. Airway resistance, bronchoalveolar lavage (BAL), and histological and immunohistochemical analyses were conducted in rats administered with single or repeated doses of captopril. This study showed that the hyperresponsiveness to bradykinin and capsaicin in captopril-treated rats was acute. Treatment with the selective B2 antagonist, HOE140 reduced bradykinin hyperresponsiveness and abolished capsaicin exacerbation in single-dose captopril-treated rats. Likewise, degeneration of TRPV1-positive neurones also reduced hyperresponsiveness to bradykinin. Single-dose captopril treatment increased leukocyte infiltration in the BAL when compared with the vehicle and this increase was reduced by TRPV1-positive neurone degeneration. However, when compared with the vehicle treatment, animals treated with repeated doses of captopril showed an increase in leukocyte influx as early as 1 h after the last captopril treatment, but this effect disappeared after 24 h. Additionally, an increase in TRPV1 expression occurred only in animals who received repeated captopril doses and the degeneration of TRPV1-positive neurones attenuated TRPV1 upregulation. In conclusion, these data strongly indicate that a treatment regimen involving multiple doses of captopril not only enhances sensitisation but also upregulates TRPV1 expression. Consequently, targeting TRPV1 could serve as a promising strategy to reduce the negative impact of captopril on the airways.

Icatibant averting mechanical ventilation in acute ischemic stroke patient with alteplase-induced orolingual angioedema.

BACKGROUND AND PURPOSE: Orolingual angioedema (OA) represents a rare but life-threatening complication among patients with acute ischemic stroke treated with intravenous thrombolysis with alteplase. Novel agents, including icatibant, are recommended in resistant patients with alteplase-induced OA who have failed to respond to first-line therapies including corticosteroids, antihistamines, and/or adrenaline. METHODS: We present a patient with alteplase-induced OA who showed substantial clinical improvement following the administration of icatibant. RESULTS: We describe a 71-year-old woman with known arterial hypertension under treatment with angiotensin-converting enzyme inhibitor, who presented with acute ischemic stroke in the territory of the right middle cerebral artery and received intravenous alteplase. During intravenous thrombolysis, the case was complicated with OA without any response to standard anaphylactic treatment including corticosteroids, dimetindene, and adrenaline. Thirty minutes after symptom onset, icatibant, a synthetic selective bradykinin B2-receptor antagonist, was administered subcutaneously. Substantial symptomatic resolution was observed only following the icatibant administration. CONCLUSIONS: This case highlights the effectiveness of icatibant in the acute management of alteplase-induced OA. In particular, icatibant administration, following first-line therapies including corticosteroids, antihistamines, and/or adrenaline, may avert tracheostomy and intubation in resistant and refractory cases with OA following intravenous thrombolysis for acute ischemic stroke.

Kinin B1 receptor and TLR4 interaction in inflammatory response.

OBJECTIVE: We aimed to broaden our understanding of a potential interaction between B1R and TLR4, considering earlier studies suggesting that lipopolysaccharide (LPS) may trigger B1R stimulation. METHODS: We assessed the impact of DBK and LPS on the membrane potential of thoracic aortas from C57BL/6, B1R, or TLR4 knockout mice. Additionally, we examined the staining patterns of these receptors in the thoracic aortas of C57BL/6 and in endothelial cells (HBMEC). RESULTS: DBK does not affect the resting membrane potential of aortic rings in C57BL/6 mice, but it hyperpolarizes preparations in B1KO and TLR4KO mice. The hyperpolarization mechanism in B1KO mice involves B2R, and the TLR4KO response is independent of cytoplasmic calcium influx but relies on potassium channels. Conversely, LPS hyperpolarizes thoracic aorta rings in both C57BL/6 and B1KO mice, with the response unaffected by a B1R antagonist. Interestingly, the absence of B1R alters the LPS response to potassium channels. These activities are independent of nitric oxide synthase (NOS). While exposure to DBK and LPS does not alter B1R and TLR4 mRNA expression, treatment with these agonists increases B1R staining in endothelial cells of thoracic aortic rings and modifies the staining pattern of B1R and TLR4 in endothelial cells. Proximity ligation assay suggests a interaction between the receptors. CONCLUSION: Our findings provide additional support for a putative connection between B1R and TLR4 signaling. Given the involvement of these receptors and their agonists in inflammation, it suggests that drugs and therapies targeting their effects could be promising therapeutic avenues worth exploring.

The future of therapeutic options for hereditary angioedema.

Hereditary angioedema (HAE) is a rare genetic condition causing unpredictable and severe episodes of angioedema that are debilitating and life-threatening. Moreover, HAE can be classified into HAE due to C1-esterase inhibitor deficiency (HAE-C1INH) or HAE with normal C1INH. Moreover, HAE-C1INH is subcategorized as types I and II based on deficient or dysfunctional circulating C1INH protein resulting from inherited or spontaneous mutations in the SERPING1 gene leading to uncontrolled factor XII/plasma kallikrein activation and excessive bradykinin production. Bradykinin-2 receptor activation leads to vasodilation, increased vascular permeability, and smooth muscle contractions, resulting in subcutaneous or submucosal fluid extravasation that can affect the face, extremities, airway, and gastrointestinal and genitourinary systems. Furthermore, HAE with normal C1INH is caused by either a known or unknown genetic mutation, and the mechanisms are less well-established but most forms are thought to be related to bradykinin signaling with a similar presentation as HAE-C1INH despite normal levels of C1INH protein and function. Current HAE management strategies include on-demand and prophylactic treatments which replace C1INH, reduce kallikrein activity, or block bradykinin binding to the bradykinin B2 receptor. With the advent of additional small molecule inhibitors, monoclonal antibodies, RNA-targeted therapies, gene therapies, and gene modification approaches, preclinical studies and human clinical trials are underway to further expand therapeutic options in HAE. This review article will briefly summarize current HAE treatments and provide an overview of potential future therapies for HAE.

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.

Platelet polyphosphates are proinflammatory and procoagulant mediators in vivo.

Platelets play a central role in thrombosis, hemostasis, and inflammation. We show that activated platelets release inorganic polyphosphate (polyP), a polymer of 60-100 phosphate residues that directly bound to and activated the plasma protease factor XII. PolyP-driven factor XII activation triggered release of the inflammatory mediator bradykinin by plasma kallikrein-mediated kininogen processing. PolyP increased vascular permeability and induced fluid extravasation in skin microvessels of mice. Mice deficient in factor XII or bradykinin receptors were resistant to polyP-induced leakage. PolyP initiated clotting of plasma via the contact pathway. Ablation of intrinsic coagulation pathway proteases factor XII and factor XI protected mice from polyP-triggered lethal pulmonary embolism. Targeting polyP with phosphatases interfered with procoagulant activity of activated platelets and blocked platelet-induced thrombosis in mice. Addition of polyP restored defective plasma clotting of Hermansky-Pudlak Syndrome patients, who lack platelet polyP. The data identify polyP as a new class of mediator having fundamental roles in platelet-driven proinflammatory and procoagulant disorders.

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.

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.

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.