Exploring disease-specific metabolite signatures in hereditary angioedema patients.

Introduction: Hereditary angioedema (HAE) is a rare, life-threatening autosomal dominant genetic disorder caused by a deficient and/or dysfunctional C1 esterase inhibitor (C1-INH) (type 1 and type 2) leading to recurrent episodes of edema. This study aims to explore HAE patients' metabolomic profiles and identify novel potential diagnostic biomarkers for HAE. The study also examined distinguishing HAE from idiopathic angioedema (AE). Methods: Blood plasma samples from 10 HAE (types 1/2) patients, 15 patients with idiopathic AE, and 20 healthy controls were collected in Latvia and analyzed using LC-MS based targeted metabolomics workflow. T-test and fold change calculation were used to identify metabolites with significant differences between diseases and control groups. ROC analysis was performed to evaluate metabolite based classification model. Results: A total of 33 metabolites were detected and quantified. The results showed that isovalerylcarnitine, cystine, and hydroxyproline were the most significantly altered metabolites between the disease and control groups. Aspartic acid was identified as a significant metabolite that could differentiate between HAE and idiopathic AE. The mathematical combination of metabolites (hydroxyproline * cystine)/(creatinine * isovalerylcarnitine) was identified as the diagnosis signature for HAE. Furthermore, glycine/asparagine ratio could differentiate between HAE and idiopathic AE. Conclusion: Our study identified isovalerylcarnitine, cystine, and hydroxyproline as potential biomarkers for HAE diagnosis. Identifying new biomarkers may offer enhanced prospects for accurate, timely, and economical diagnosis of HAE, as well as tailored treatment selection for optimal patient care.

Repeated attacks of hereditary angioedema in pediatric female.

A 16-year-old female presented to an outpatient clinic with a 13-year history of recurrent episodes of abdominal pain, vomiting and mild cutaneous swelling, either spontaneously or following minor trauma. The episodes occurred every 1-2 months. There was no family history of a similar complaint or hereditary angio-oedema (HAE). At the age of 16, evaluation confirmed the diagnosis of HAE type II, characterised by low C4 levels and reduced C1 esterase inhibitor function. The patient was prescribed tranexamic acid 1 g twice daily as well as C1 esterase inhibitor used as rescue medication during symptomatic episodes. This case report emphasises the importance of considering a diagnosis of HAE in patients with recurrent, unexplained abdominal pain, even in the absence of a positive family history of HAE.Abbreviations: ANA Antinuclear antibodies; C1-INH C1-inhibitor; CBC Complete blood count; FMF Familial Mediterranean fever; HAE Hereditary angioedema; IBD Inflammatory bowel diseases; SDP Solvent detergent-treated plasma; SLE Lupus erythematosus.

Transmission patterns of C1-INH deficiency hereditary angioedema favors a wild-type male offspring: Our experience at Chandigarh, India.

BACKGROUND: Deficiency of C1-inhibitor (C1-INH) protein, caused by pathogenic variants in the Serpin family G member 1 (SERPING1) gene, is the commonest pathophysiological abnormality (in ∼95 % cases) in patients with hereditary angioedema (HAE). C1-INH protein provides negative control over kallikrein-kinin system (KKS). Although the inheritance of the HAE-C1-INH is autosomal dominant, female predominance has often been observed in patients with HAE. OBJECTIVE: To analyze the risk of transmission of SERPING1 gene variant from father or mother to their offspring. METHODS: Pedigree charts of 42 families with a confirmed diagnosis of HAE-C1-INH and a pathogenic variant in the SERPING1 gene were analysed. Patients with HAE who had had at least one child were included for analyses to assess the risk of transmission from the father or mother to their offspring. RESULTS: Overall, 49 % (189/385) of all offspring inherited the genetic defect. In the subgroup analyses, 54.8 % (90/164) female offspring and 44.8 % (99/221; p < 0.02) male offspring inherited the genetic defect. Inheritance of the genetic defect was significantly lower in male offspring. Fathers with SERPING1 gene variant had a statistically significant skewed transmission of the wild type to the male offspring as compared to the variant (57.8 % wild type vs. 42.1 % variant; p < 0.02), whereas no statistically significant difference was found when a father transmitted the variant to a female offspring. Mothers with SERPING1 gene variant had no statistically significant difference in variant transmission to male or female offsprings. CONCLUSION: Results of the study suggest that the transmission pattern of SERPING1 gene variant favours the transmission of wild-type alleles in males, especially when the father is the carrier; hence, overall, fewer males and more female offspring inherited the variant. This could be because of a selection of wild-type male sperms during spermatogenesis, as the KLK system has been reported to play a crucial role in the regulation of spermatogenesis. Although, a similar pattern was observed in the maternal transmission of the SERPING1 gene variant; the difference was not statistically significant, likely because of a small sample size.

Neuroinflammatory gene expression profiles of reactive glia in the substantia nigra suggest a multidimensional immune response to alpha synuclein inclusions.

Parkinson's disease (PD) pathology is characterized by alpha-synuclein (α-syn) aggregates, degeneration of dopamine neurons in the substantia nigra pars compacta (SNpc), and neuroinflammation. The presence of reactive glia correlates with deposition of pathological α-syn in early-stage PD. Thus, understanding the neuroinflammatory response of microglia and astrocytes to synucleinopathy may identify therapeutic targets. Here we characterized the neuroinflammatory gene expression profile of reactive microglia and astrocytes in the SNpc during early synucleinopathy in the rat α-syn pre-formed fibril (PFF) model. Rats received intrastriatal injection of α-syn PFFs and expression of immune genes was quantified with droplet digital PCR (ddPCR), after which fluorescent in situ hybridization (FISH) was used to localize gene expression to microglia or astrocytes in the SNpc. Genes previously associated with reactive microglia (Cd74, C1qa, Stat1, Axl, Casp1, Il18, Lyz2) and reactive astrocytes (C3, Gbp2, Serping1) were significantly upregulated in the SN of PFF injected rats. Localization of gene expression to SNpc microglia near α-syn aggregates identified a unique α-syn aggregate microglial gene expression profile characterized by upregulation of Cd74, Cxcl10, Rt-1a2, Grn, Csf1r, Tyrobp, C3, C1qa, Serping1 and Fcer1g. Importantly, significant microglial upregulation of Cd74 and C3 were only observed following injection of α-syn PFFs, not α-syn monomer, confirming specificity to α-syn aggregation. Serping1 expression also localized to astrocytes in the SNpc. Interestingly, C3 expression in the SNpc localized to microglia at 2- and 4-months post-PFF, but to astrocytes at 6-months post-PFF. We also observed expression of Rt1-a2 and Cxcl10 in SNpc dopamine neurons. Cumulatively our results identify a dynamic, yet reproducible gene expression profile of reactive microglia and astrocytes associated with early synucleinopathy in the rat SNpc.

Efficacy and Safety of Rituximab-Based Treatments in Angioedema With Acquired C1-Inhibitor Deficiency.

BACKGROUND: Angioedema (AE) due to acquired C1-inhibitor (C1-INH) deficiency (AAE-C1-INH) is related to excessive consumption of C1-INH or to anti-C1-INH antibodies, and is frequently associated with lymphoproliferative syndromes or monoclonal gammopathies. Standard of care for prophylactic treatment in this condition is not established. Rituximab may be effective to prevent attacks, especially if the lymphoid hemopathy is controlled, but data are scarce. OBJECTIVE: To evaluate efficacy of rituximab in AAE-C1-INH. METHODS: A retrospective multicenter study was carried out in France, including patients with AAE-C1-INH treated with rituximab between April 2005 and July 2019. RESULTS: Fifty-five patients with AAE-C1-INH were included in the study, and 23 of them had an anti-C1-INH antibody. A lymphoid malignancy was identified in 39 patients, and a monoclonal gammopathy in 9. There was no associated condition in 7 cases. Thirty patients received rituximab alone or in association with chemotherapy (n = 25). Among 51 patients with available follow-up, 34 patients were in clinical remission and 17 patients had active AE after a median follow-up of 3.9 years (interquartile range, 1.5-7.7). Three patients died. The presence of anti-C1-INH antibodies was associated with a lower probability of AE remission (hazard ratio, 0.29 [95% CI, 0.12-0.67]; P = .004). Relapse was less frequent in patients with lymphoma (risk ratio, 0.27 [95% CI, 0.09-0.80]; P = .019) and in patients treated with rituximab and chemotherapy (risk ratio, 0.31 [95% CI, 0.12-0.79]; P = .014). CONCLUSIONS: Rituximab is an efficient and well-tolerated therapeutic option in AE, especially in lymphoid malignancies and in the absence of detectable anti-C1-INH antibodies.

Clinical Evaluation of Pediatric Patients with Hereditary Angioedema.

Hereditary angioedema is a rare, potentially life-threatening disease. There is a lack of data describing the clinical course of hereditary angioedema (HAE) in children. We aimed to evaluate the clinical characteristics of pediatric patients with hereditary angioedema: The age of disease onset, age at diagnosis, the frequency of angioedema attacks, the total number of attacks before diagnosis, the regions where angioedema attacks were observed, accompanying abdominal pain, and serum levels of C4 and C1 esterase inhibitor were obtained and recorded. In addition, the results of SERPING1 (C1INH) gene sequence analysis of the patients in this group were also collected from medical records and recorded. While none of the patients reported a skin rash as a symptom of attack, there was formication observed in the region of angioedema in 46.9% (n = 15) of the patients and pruritus in 6.2% (n = 2) of the patients. At disease onset, the complaints of the patients regarding location of edema were on the hands of 32.3% (n = 10), on the feet of 9.7% (n = 3), on the faces of 25.7% (n = 8), and abdominal attacks in 32.3% of the patients (n = 10). Four different variants, one of which was novel, were detected in the SERPING1 gene in eight different families. The results of this study suggest that hereditary angioedema is diagnosed only when the patient requests examination following recurrent angioedema. Severe laryngeal edema attacks in patients without a diagnosis of HAE are fatal at a higher rate than attacks in patients with a diagnosis. Thus, awareness of the symptoms of HAE is necessary, and correct diagnosis is essential to proper treatment.

Uncovering the true burden of hereditary angioedema due to C1-inhibitor deficiency: A focus on the Asia-Pacific region.

Hereditary angioedema (HAE) due to C1-inhibitor deficiency or dysfunction is a rare genetic disorder that causes recurrent episodes of swelling in various parts of the body. Treatment goals of HAE aim to "normalize" life for all patients; however, lack of diagnostic facilities and limited access to effective treatment options in developing nations cause delays in diagnosis and place a significant burden on patients. In this review, we aim to highlight the burden of disease caused by C1-inhibitor HAE across the Asia-Pacific region, considering its epidemiology, morbidity and mortality, and socioeconomic and psychological impact. We also review the availability of guideline-recommended diagnostic facilities and treatments, and how patients are currently managed. Data were collected from published literature and HAE experts in the region, who provided information regarding diagnosis and management in their countries. Current practice was reviewed against international guidelines, as well as local guidelines/consensus used in Australia, Japan, and China. Suggestions are provided for improving the time to diagnosis in the region, increasing access to guideline-recommended treatments, and providing support to reduce the burden on patients and caregivers. There is an urgent need to improve HAE services and provide access to life-saving treatment in developing countries, and efforts should be made to increase awareness of guideline recommendations in high-income economies that do not currently provide long-term prophylactic treatments.

Pathogenic variant in SERPING1 gene causing autosomal dominant hereditary angioedema in early childhood.

A female in early childhood presented with 6 months of transient swelling of multiple areas of her body, often, but not always, associated with minor trauma. Labs drawn were significant for low C4, low CH50, low C1 esterase inhibitor (C1-INH) antigen and low C1-INH function, which is concerning for hereditary angioedema (HAE) with abnormal C1-INH. Genetic testing through the Invitae Hereditary Angioedema Panel revealed a variant in the SERPING1 gene, c.686-7C>G (Intronic), which was classified as a variant of unknown significance, but is likely pathogenic given patient's clinical presentation and recent functional proof of pathogenicity. HAE should be recognised in paediatric patients even without family history. Recognising the symptoms of HAE and confirming diagnosis in early childhood has become more important recently as the first prophylactic therapy, lanadelumab, was approved in February 2023 for long-term prophylaxis in early childhood, which can significantly improve morbidity and quality of life.

How Does Pregnancy and Type of Delivery Affect the Clinical Course of Hereditary Angioedema?

INTRODUCTION: Knowledge on the clinical course of hereditary angioedema (HAE) during pregnancy, delivery, and breastfeeding is very limited. In this study, we aimed to evaluate the course of HAE during these periods. METHODS: The HAE attacks C1-INH prophylaxis before and during pregnancy and during breastfeeding, and the delivery types were retrospectively determined. The severity of attacks was assessed by a 10-point Visual Analogue Scale (VAS). RESULTS: We evaluated 88 pregnancies in 48 HAE patients among whom 20 were primiparous. Among those who had a HAE diagnosis during pregnancy (n = 34), the median attack numbers before pregnancy, during pregnancy, breastfeeding, and after breastfeeding were 17, 39, 24, and 14 (before pregnancy vs. pregnancy, p < 0.001; during pregnancy vs. breastfeeding, p = 0.001). The mean VASs (SD) were 6.59 (1.82), 8.33 (1.58), 7.32 (1.66), and 6.95 (1.90) (before pregnancy vs. pregnancy, p < 0.001; during pregnancy vs. breastfeeding, p = 0.016), respectively. Among those who received a HAE diagnosis after pregnancy (n = 54), the number (59.3%) and the severity (60%) of HAE attacks were high in pregnancy. 47 of the deliveries were normal vaginal delivery (NVD). Regional anesthesia was applied in 8 NVDs. 20 of caesarean deliveries were performed under general anesthesia, and 21 were under spinal anesthesia. Lowest numbers of attacks were found in patients who did not receive anesthesia during NVD (p = 0.001). CONCLUSION: The course of HAE can be worse during pregnancy and breastfeeding. NVD is related to fewer HAE attacks and prophylaxis with C1-INH during NVD is not necessary to prevent a HAE attack.

Systematic Approach Revealed SERPING1 Splicing-Affecting Variants to be Highly Represented in the Czech National HAE Cohort.

Hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE) is a rare and life-threatening condition characterized by recurrent localized edema. We conducted a systematic screening of SERPING1 defects in a cohort of 207 Czech patients from 85 families with C1-INH-HAE. Our workflow involved a combined strategy of sequencing extended to UTR and deep intronic regions, advanced in silico prediction tools, and mRNA-based functional assays. This approach allowed us to detect a causal variant in all families except one and to identify a total of 56 different variants, including 5 novel variants that are likely to be causal. We further investigated the functional impact of two splicing variants, namely c.550 + 3A > C and c.686-7C > G using minigene assays and RT-PCR mRNA analysis. Notably, our cohort showed a considerably higher proportion of detected splicing variants compared to other central European populations and the LOVD database. Moreover, our findings revealed a significant association between HAE type 1 missense variants and a delayed HAE onset when compared to null variants. We also observed a significant correlation between the presence of the SERPING1 variant c.-21 T > C in the trans position to causal variants and the frequency of attacks per year, disease onset, as well as Clinical severity score. Overall, our study provides new insights into the genetic landscape of C1-INH-HAE in the Czech population, including the identification of novel variants and a better understanding of genotype-phenotype correlations. Our findings also highlight the importance of comprehensive screening strategies and functional analyses in improving the C1-INH-HAE diagnosis and management.

Hereditary Angioedema.

Hereditary angioedema (HAE) is a rare autosomal dominant genetic disorder that usual results from a decreased level of functional C1-INH and clinically manifests with intermittent attacks of swelling of the subcutaneous tissue or submucosal layers of the respiratory or gastrointestinal tracts. Laboratory studies and radiographic imaging have limited roles in evaluation of patients with acute attacks of HAE except when the diagnosis is uncertain and other processes must be ruled out. Treatment begins with assessment of the airway to determine the need for immediate intervention. Emergency physicians should understand the pathophysiology of HAE to help guide management decisions.

Restriction of C1-inhibitor activity in hereditary angioedema by dominant-negative effects of disease-associated SERPING1 gene variants.

BACKGROUND: Patients with hereditary angioedema experience recurrent, sometimes life-threatening, attacks of edema. It is a rare genetic disorder characterized by genetic and clinical heterogenicity. Most cases are caused by genetic variants in the SERPING1 gene leading to plasma deficiency of the encoded protein C1 inhibitor (C1INH). More than 500 different hereditary angioedema-causing variants have been identified in the SERPING1 gene, but the disease mechanisms by which they result in pathologically low C1INH plasma levels remain largely unknown. OBJECTIVES: The aim was to describe trans-inhibitory effects of full-length or near full-length C1INH encoded by 28 disease-associated SERPING1 variants. METHODS: HeLa cells were transfected with expression constructs encoding the studied SERPING1 variants. Extensive and comparative studies of C1INH expression, secretion, functionality, and intracellular localization were carried out. RESULTS: Our findings characterized functional properties of a subset of SERPING1 variants allowing the examined variants to be subdivided into 5 different clusters, each containing variants sharing specific molecular characteristics. For all variants except 2, we found that coexpression of mutant and normal C1INH negatively affected the overall capacity to target proteases. Strikingly, for a subset of variants, intracellular formation of C1INH foci was detectable only in heterozygous configurations enabling simultaneous expression of normal and mutant C1INH. CONCLUSIONS: We provide a functional classification of SERPING1 gene variants suggesting that different SERPING1 variants drive the pathogenicity through different and in some cases overlapping molecular disease mechanisms. For a subset of gene variants, our data define some types of hereditary angioedema with C1INH deficiency as serpinopathies driven by dominant-negative disease mechanisms.

Biochemistry, molecular genetics, and clinical aspects of hereditary angioedema with and without C1 inhibitor deficiency.

Hereditary angioedema (HAE) is a rare disorder characterized by cutaneous and submucosal swelling caused mostly by excessive local bradykinin production. Bradykinin is a vasoactive peptide generated by the limited proteolysis of high molecular weight kininogen (HMWK) by plasma kallikrein via the contact activation system. The contact activation system occurs not only in solution but also on the cell surface. Factor XII (FXII), prekallikrein, and HMWK are assembled on the endothelial cell surface via several proteins, including a trimer of a receptor for globular C1q domain in a Zn2+-dependent manner, and the reciprocal activation on the cell surface is believed to be physiologically important in vivo. Thus, the contact activation system leads to the activation of coagulation, complement, inflammation, and fibrinolysis. C1-inhibitor (C1-INH) is a plasma protease inhibitor that is a member of the serpin family. It mainly inhibits activated FXII (FXIIa), plasma kallikrein, and C1s. C1-INH hereditary deficiency induces HAE (HAE-C1-INH) due to excessive bradykinin production via the incomplete inhibition of plasma kallikrein and FXIIa through the low C1-INH level. HAE is also observed in patients with normal C1-INH (HAEnCI) who carry pathogenic variants in genes of factor XII, plasminogen, angiopoietin 1, kininogen, myoferlin, and heparan sulfate 3-O-sulfotransferase 6, which are associated with bradykinin production and/or vascular permeability. HAE-causing pathways triggered by pathogenic variants in patients with HAE-C1-INH and HAEnCI are reviewed and discussed.

Successful treatment of post-pericardiotomy syndrome via C1 inhibitor replacement therapy in a hereditary angioedema patient with Marfan syndrome.

BACKGROUND: Hereditary angioedema with C1 inhibitor deficiency (HAE-C1INH) is caused by dysfunctional C1-INH protein due to mutations in the SERPING1 gene encoding C1-INH. Marfan syndrome is a genetic connective tissue disease that affects the cardiovascular and ocular systems along with the skeletal system. In this case, we present the successful treatment of post-pericardiotomy syndrome unresponsive to classical therapy, which has not been described in the literature. The syndrome developed in a patient with hereditary angioedema (HAE) who underwent open heart surgery due to cardiac involvement in Marfan syndrome. CASE: A nine-year-old male HAE-C1INH patient underwent open heart surgery secondary to cardiac involvement caused by Marfan syndrome. To prevent HAE attacks, 1000 units of C1 inhibitor concentrate therapy were given 2 hours before and 24 hours after the operation. Post-pericardiotomy syndrome was diagnosed on the postoperative second day and ibuprofen 15 mg/kg/day (3 weeks) was started. Since there was no response to classical treatment on the 21st postoperative day, C1 inhibitor concentrate treatment was planned as 1000 units/ dose for 2 days a week considering a prolonged hereditary angioedema attack. In the second week of treatment, complete recovery was achieved for pericardial effusion with a total of 4 doses. CONCLUSIONS: We emphasize that in patients with hereditary angioedema undergoing this treatment, care should be taken in terms of complications that may be associated with the disease even if short-term prophylaxis is given before operations and that longer-term use of C1 inhibitor concentrate has a place in treatment.

Hereditary angio-oedema with normal C1-INH, developing recurrent acute abdomen after taking low-dose oestrogen-progestin: A case report.

Hereditary angio-oedema (HAE) is a rare genetic disease characterised by repeated episodes of temporary organ swelling. Three types of HAE are known, of which HAE with normal C1 inactivator is difficult to be diagnosed due to its lack of laboratory abnormalities. Here, we describe a case of HAE with normal C1 inactivator and recurrent acute abdomen following low-dose oestrogen-progestin therapy. Notably, genetic analysis by Sanger sequencing led to the identification of a recurrent heterozygous missense mutation c.988A > G (p.K330E) in the plasminogen (PLG) gene of the patient. Prophylactic tranexamic acid and on-demand selective bradykinin B2 receptor blockers are used to treat her symptoms.

Gene Mutations Linked to Hereditary Angioedema in Solitary Angioedema Patients With Normal C1 Inhibitor.

BACKGROUND: Chronic recurrent angioedema without wheals (CRA) with normal C1 inhibitor (C1-INH) that is unresponsive to antihistamines may involve patients with recurrent angioedema of unknown cause (ie, so-called non-histaminergic idiopathic angioedema) as well as patients with hereditary angioedema with normal C1-INH (HAEnCI) when HAEnCI occurs in only one family member. OBJECTIVE: To identify patients with one of type of HAEnCI in a group of patients with CRA with normal C1-INH that was unresponsive to antihistamines. METHODS: A total of 132 patients with CRA and normal C1-INH that was unresponsive to antihistamines underwent mutational and clinical analysis. The presence of hereditary angioedema-specific mutations in Factor XII, plasminogen, ANGPT1, KNG1, MYOF, and HS3ST6 genes was tested by Sanger sequencing. When an HAEnCI-causing mutation was identified, available asymptomatic relatives were genetically tested. RESULTS: In 116 of 132 solitary patients with CRA (87.9%), none of the six HAEnCI-linked mutations could be found. Ten patients (7.6%) had the Factor XII mutation c.983C>A (p.T328K) and six (4.5%) the plasminogen mutation c.988A>G (p.K330E). Other mutations linked to HAEnCI were not found in this patient series. In the 16 families with HAEnCI, 11 asymptomatic carriers of one of the HAEnCI-linked mutations were identified. CONCLUSIONS: A search for HAEnCI-linked mutations in patients with solitary CRA may lead to the detection of patients and families with HAEnCI. This is important because family members can be identified who are at risk for developing potentially life-threatening angioedema, although they were previously asymptomatic. Without genetic investigation, the risk for an HAEnCI would have remained undetected in these patients and asymptomatic relatives.

CU06-1004 alleviates vascular hyperpermeability in a murine model of hereditary angioedema by protecting the endothelium.

BACKGROUND: Over-release of the vasoactive peptide bradykinin (BK) due to mutation in the SERPING1 gene is the leading cause of hereditary angioedema (HAE). BK directly activates endothelial cells and increases vascular permeability by disrupting the endothelial barrier, leading to angioedema affecting face, lips, extremities, gastrointestinal tract, and larynx. Although various pharmacological treatment options for HAE became available during the last decade, they are presently limited and pose a major economic burden on patients. To identify additional therapeutic options for HAE, we evaluated the effect of CU06-1004, an endothelial dysfunction blocker, on BK-induced vascular hyperpermeability and the HAE murine model. METHODS: To investigate the effect of CU06-1004 on BK-induced vascular hyperpermeability in vivo, we pre-administrated WT mice with the drug and then induced vascular leakage through intravenous injection of BK and observed vascular alternation. Then, SERPING1 deficient mice were used for a HAE murine model. For an in vitro model, the HUVEC monolayer was pre-treated with CU06-1004 and then stimulated with BK. RESULTS: Bradykinin disrupted the endothelial barrier and formed interendothelial cell gaps, leading to hyperpermeability in vivo and in vitro. However, CU06-1004 treatment protected the endothelial barrier by suppressing Src and myosin light chain activation via BK and alleviated hyperpermeability. CONCLUSION: Our study shows that CU06-1004 oral administration significantly reduced vascular hyperpermeability in the HAE murine model by protecting the endothelial barrier function against BK stimulation. Therefore, protecting endothelium against BK with CU06-1004 could serve as a potential prophylactic/therapeutic approach for HAE patients.