Altered levels of phospholipases C, diacylglycerols, endocannabinoids, and N-acylethanolamines in patients with hereditary angioedema due to FXII mutation.

BACKGROUND: Hereditary angioedema (HAE) is a rare genetic disorder characterized by local, self-limiting edema due to temporary increase in vascular permeability. HAE with normal C1 esterase inhibitor (C1INH) activity includes the form with mutations in the F12 gene encoding for coagulation factor XII (FXII-HAE) causing an overproduction of bradykinin (BK) leading to angioedema attack. BK binding to B2 receptors (BK2R) leads to an activation of phospholipase C (PLC) and subsequent generation of second messengers: diacylglycerols (DAGs) and possibly the endocannabinoids (eCBs), 2-arachidonoylglycerol (2-AG) and anandamide (AEA), and eCB-related N-acylethanolamines [palmitoylethanolamide (PEA) and oleoylethanolamide (OEA)]. To date, there are no data on the role of these lipid mediators in FXII-HAE. METHODS: Here, we analyzed plasma levels of PLC, DAGs, and eCBs in 40 patients with FXII-HAE and 40 sex- and age-matched healthy individuals. RESULTS: Plasma PLC activity was increased in FXII-HAE patients compared to controls. Concentrations of DAG 18:1-20:4, a lipid second messenger produced by PLC, were higher in FXII-HAE compared to controls, and positively correlated with PLC activity and cleaved high molecular kininogen (cHK). Also the concentrations of the DAG metabolite, 2-AG were altered in FXII-HAE. AEA and OEA were decreased in FXII-HAE patients compared to controls; by contrast, PEA, was increased. The levels of all tested mediators did not differ between symptomatic and asymptomatic patients. Moreover, C1INH-HAE patients had elevated plasma levels of PLC, which correlated with cHK, but the levels of DAGs and eCBs were the same as controls. CONCLUSIONS: BK overproduction and BKR2 activation are linked to alteration of PLCs and their metabolites in patients with FXII-HAE. Our results may pave way to investigations on the functions of these mediators in the pathophysiology of FXII-HAE, and provide new potential biomarkers and therapeutic targets.

The international WAO/EAACI guideline for the management of hereditary angioedema-The 2021 revision and update.

Hereditary angioedema (HAE) is a rare and disabling disease for which early diagnosis and effective therapy are critical. This revision and update of the global WAO/EAACI guideline on the diagnosis and management of HAE provides up-to-date guidance for the management of HAE. For this update and revision of the guideline, an international panel of experts reviewed the existing evidence, developed 28 recommendations, and established consensus by an online DELPHI process. The goal of these recommendations and guideline is to help physicians and their patients in making rational decisions in the management of HAE with deficient C1 inhibitor (type 1) and HAE with dysfunctional C1 inhibitor (type 2), by providing guidance on common and important clinical issues, such as: (1) How should HAE be diagnosed? (2) When should HAE patients receive prophylactic on top of on-demand treatment and what treatments should be used? (3) What are the goals of treatment? (4) Should HAE management be different for special HAE patient groups such as children or pregnant/breast-feeding women? and (5) How should HAE patients monitor their disease activity, impact, and control? It is also the intention of this guideline to help establish global standards for the management of HAE and to encourage and facilitate the use of recommended diagnostics and therapies for all patients.

Novel hereditary angioedema linked with a heparan sulfate 3-O-sulfotransferase 6 gene mutation.

BACKGROUND: Hereditary angioedema (HAE) is a potentially fatal disorder resulting in recurrent attacks of severe swelling. It may be associated with a genetic deficiency of functional C1 inhibitor or with normal C1 inhibitor (HAEnCI). In families with HAEnCI, HAE-linked mutations in the F12, PLG, KNG1, ANGPT1, or MYOF genes have been identified. In many families with HAEnCI the genetic cause of the disease is currently unknown. OBJECTIVE: The aim of this study was to identify a novel disease-linked mutation for HAEnCI. METHODS: The study methods comprised whole exome sequencing, Sanger sequencing analysis, pedigree analysis, bioinformatic analysis of the mutation, and biochemical analysis of parameters of the kallikrein-kinin (contact) system. RESULTS: By performing whole exome sequencing on a multigenerational family with HAEnCI we were able to identify the heparan sulfate (HS)-glucosamine 3-O-sulfotransferase 6 (HS3ST6) mutation c.430A>T (p.Thr144Ser) in all 3 affected family members who were sequenced. This gene encodes HS-glucosamine 3-O-sulfotransferase 6 (3-OST-6), which is involved in the last step of HS biosynthesis. The p.Thr144Ser mutation is likely to affect the interaction between 2 ß-sheets stabilizing the active center of the 3-OST-6 protein. CONCLUSIONS: We conclude that mutant 3-OST-6 fails to transfer sulfo groups to the 3-OH position of HS, resulting in incomplete HS biosynthesis. This likely affects cell surface interactions of key players in angioedema formation and is a novel mechanism for disease development.

Prevention of Hereditary Angioedema Attacks with a Subcutaneous C1 Inhibitor.

BACKGROUND: Hereditary angioedema is a disabling, potentially fatal condition caused by deficiency (type I) or dysfunction (type II) of the C1 inhibitor protein. In a phase 2 trial, the use of CSL830, a nanofiltered C1 inhibitor preparation that is suitable for subcutaneous injection, resulted in functional levels of C1 inhibitor activity that would be expected to provide effective prophylaxis of attacks. METHODS: We conducted an international, prospective, multicenter, randomized, double-blind, placebo-controlled, dose-ranging, phase 3 trial to evaluate the efficacy and safety of self-administered subcutaneous CSL830 in patients with type I or type II hereditary angioedema who had had four or more attacks in a consecutive 2-month period within 3 months before screening. We randomly assigned the patients to one of four treatment sequences in a crossover design, each involving two 16-week treatment periods: either 40 IU or 60 IU of CSL830 per kilogram of body weight twice weekly followed by placebo, or vice versa. The primary efficacy end point was the number of attacks of angioedema. Secondary efficacy end points were the proportion of patients who had a response (≥50% reduction in the number of attacks with CSL830 as compared with placebo) and the number of times that rescue medication was used. RESULTS: Of the 90 patients who underwent randomization, 79 completed the trial. Both doses of CSL830, as compared with placebo, reduced the rate of attacks of hereditary angioedema (mean difference with 40 IU, -2.42 attacks per month; 95% confidence interval [CI], -3.38 to -1.46; and mean difference with 60 IU, -3.51 attacks per month; 95% CI, -4.21 to -2.81; P<0.001 for both comparisons). Response rates were 76% (95% CI, 62 to 87) in the 40-IU group and 90% (95% CI, 77 to 96) in the 60-IU group. The need for rescue medication was reduced from 5.55 uses per month in the placebo group to 1.13 uses per month in the 40-IU group and from 3.89 uses in the placebo group to 0.32 uses per month in the 60-IU group. Adverse events (most commonly mild and transient local site reactions) occurred in similar proportions of patients who received CSL830 and those who received placebo. CONCLUSIONS: In patients with hereditary angioedema, the prophylactic use of a subcutaneous C1 inhibitor twice weekly significantly reduced the frequency of acute attacks. (Funded by CSL Behring; COMPACT EudraCT number, 2013-000916-10 , and ClinicalTrials.gov number, NCT01912456 .).

Hereditary angioedema in children and adolescents - A consensus update on therapeutic strategies for German-speaking countries.

BACKGROUND/METHODS: At a consensus meeting in August 2018, pediatricians and dermatologists from German-speaking countries discussed the therapeutic strategy for the treatment of pediatric patients with type I and II hereditary angioedema due to C1 inhibitor deficiency (HAE-C1-INH) for Germany, Austria, and Switzerland, taking into account the current marketing approval status. HAE-C1-INH is a rare disease that usually presents during childhood or adolescence with intermittent episodes of potentially life-threatening angioedema. Diagnosis as early as possible and an optimal management of the disease are important to avoid ineffective therapies and to properly treat swelling attacks. This article provides recommendations for developing appropriate treatment strategies in the management of HAE-C1-INH in pediatric patients in German-speaking countries. An overview of available drugs in this age-group is provided, together with their approval status, and study results obtained in adults and pediatric patients. RESULTS/CONCLUSION: Currently, plasma-derived C1 inhibitor concentrates have the broadest approval status and are considered the best available option for on-demand treatment of HAE-C1-INH attacks and for short- and long-term prophylaxis across all pediatric age-groups in German-speaking countries. For on-demand treatment of children aged 2 years and older, recombinant C1-INH and bradykinin-receptor antagonist icatibant are alternatives. For long-term prophylaxis in adolescents, the parenteral kallikrein inhibitor lanadelumab has recently been approved and can be recommended due to proven efficacy and safety.

Hereditary angioedema in a single family with specific mutations in both plasminogen and SERPING1 genes.

BACKGROUND: Hereditary angioedema (HAE) is a group of genetic diseases characterized by recurrent, painful and potentially lethal tissue swelling. The most common form results from mutations in the SERPING1 gene, leading to reduced function of complement 1 inhibitor (C1-INH). Rarer forms with normal C1-INH may arise from mutations in the coagulation factor F12 gene, but mostly the genetic background is unknown. Recently, a novel HAE mutation in the plasminogen (PLG) gene was shown. PATIENTS AND METHODS: We analyzed the various clinical manifestations of HAE in 14 related patients using clinical data, biochemical analysis for C1-INH and C4 as well as gene sequencing. RESULTS: Patients' symptoms were assigned to two different forms of HAE. In ten patients suffering from swelling of the lips or tongue but not of the extremities, a mutation in the PLG gene (c.988A>G) was found whereas in the only four patients with swelling of the gastrointestinal tract and extremities, a mutation in the SERPING1 gene (c.1480C>T) was identified. In two cases this was additional to PLG c.988A>G. CONCLUSIONS: This unique finding of two different HAE-specific mutations in a large family not only explains the divergent phenotypes but also supports a genotype-phenotype correlation showing that abdominal attacks and swelling of the extremities are common with HAE-C1-INH but unusual with HAE-PLG.

[Hereditary angioedema]. / Hereditäres Angioödem.

Hereditary angioedema (HAE) encompasses a heterogeneous group of diseases with similar phenotypes but different underlying genotypes. Specific clinical signs may point to HAE as opposed to histaminergic angioedema: the typical prolonged development of angioedema over time, positive family history, a lack of response to antihistamines and steroids and response to bradykinin antagonists are typical signs of HAE. The different types of HAE may be associated with a severe clinical course. They are life-long conditions and are still potentially life-threatening. The quality of life of patients with HAE may be considerably impaired. Management plans should be individualized, which is facilitated by the variety of specific medicastions available.

Deficiency of plasminogen activator inhibitor 2 in plasma of patients with hereditary angioedema with normal C1 inhibitor levels.

BACKGROUND: Hereditary angioedema with normal C1 inhibitor levels (HAE-N) is associated with a Factor XII mutation in 30% of subjects; however, the role of this mutation in the pathogenesis of angioedema is unclear. OBJECTIVE: We sought evidence of abnormalities in the pathways of bradykinin formation and bradykinin degradation in the plasma of patients with HAE-N both with and without the mutation. METHODS: Bradykinin was added to plasma, and its rate of degradation was measured by using ELISA. Plasma autoactivation was assessed by using a chromogenic assay of kallikrein formation. Plasminogen activator inhibitors (PAIs) 1 and 2 were also measured by means of ELISA. RESULTS: PAI-1 levels varied from 0.1 to 4.5 ng/mL (mean, 2.4 ng/mL) in 23 control subjects, from 0.0 to 2 ng/mL (mean, 0.54 ng/mL) in patients with HAE-N with a Factor XII mutation (12 samples), and from 0.0 to 3.7 ng/mL (mean, 1.03 ng/mL) in patients with HAE-N without a Factor XII mutation (11 samples). PAI-2 levels varied from 25 to 87 ng/mL (mean, 53.8 ng/mL) in control subjects and were 0 to 25 ng/mL (mean, 4.3 ng/mL) in patients with HAE-N with or without the Factor XII mutation. Autoactivation at a 1:2 dilution was abnormally high in 8 of 17 patients with HAE-N (4 in each subcategory) and could be corrected by supplemental C1 inhibitor in 4 of them. Bradykinin degradation was markedly abnormal in 1 of 23 patients with HAE-N and normal in the remaining 22 patients. CONCLUSIONS: Bradykinin degradation was normal in all but 1 of 23 patients with HAE-N studied. By contrast, there was a marked abnormality in PAI-2 levels in patients with HAE-N that is not seen in patients with C1 inhibitor deficiency. PAI-1 levels varied considerably, but a statistically significant difference was not seen. A link between excessive fibrinolysis and bradykinin generation that is estrogen dependent is suggested.

Shortened Activated Partial Thromboplastin Time May Help in Diagnosing Hereditary and Acquired Angioedema.

OBJECTIVE: To evaluate whether activated partial thromboplastin time (APTT) could be used in the laboratory diagnosis of hereditary or acquired angioedema (HAE or AAE) with and without C1 inhibitor (C1-INH) deficiency. METHODS: In a prospective investigation, APTT and other coagulation parameters were determined in 149 adult patients with various types of angioedema and in 26 healthy participants (HP). RESULTS: Mean APTT was significantly shortened in HAE-C1-INH type I (p < 0.0001) and type II (p = 0.0017) and in AAE-C1-INH (p < 0.0001) compared to the HP. APTT was shortened under the reference range (26-36 s) in 33/45 (73.3%) patients with HAE-C1-INH, 10/15 (66.7%) patients with AAE-C1-INH, 4/27 (14.8%) patients with HAE with normal C1-INH, 1/32 (3.1%) patients with histaminergic angioedema, 4/30 (13.3%) patients with nonhistaminergic angioedema and in 2/26 (7.7%) HP. Thus, a shortened APTT was obtained in 8-9 times more patients with angioedema due to C1-INH deficiency when compared to patients with various forms of angioedema with normal C1-INH and also to HP. CONCLUSIONS: A shortened APTT may help to diagnose HAE-C1-INH and AAE-C1-INH when determination of C1-INH is not yet available.

Efficacy of Different Medical Therapies for the Treatment of Acute Laryngeal Attacks of Hereditary Angioedema due to C1-esterase Inhibitor Deficiency.

BACKGROUND: Hereditary angioedema (HAE) is a rare disease characterized by C1-esterase inhibitor (C1-INH) deficiency, resulting in periodic attacks of acute edema, which can be life-threatening if they occur in the upper airway. No head-to-head comparisons of different treatment options for acute HAE attacks are available. Because immediate symptom relief is critical for potentially life-threatening laryngeal attacks, it is important to determine the treatment option that provides optimal treatment response. OBJECTIVE: Review and compare data from clinical studies that evaluated the efficacy and safety of treatments for laryngeal HAE attacks. METHODS: We conducted an indirect comparison of clinical outcomes from prospective studies for treatment of 881 acute laryngeal attacks with plasma-derived C1-INH concentrate (pdC1-INH) at fixed doses (500 or 1000 U) or a body weight-adjusted dose (20 U/kg), recombinant C1-INH concentrate at a fixed dose (2100 U), or a body weight-adjusted dose (50 U/kg), icatibant (30 mg), or ecallantide (30 mg). Comparisons included time to onset of symptom relief and need for re-dosing or emergency procedures. RESULTS: The median time to onset of symptom relief ranged between 15 min and approximately 2 h, and was shortest with body weight-adjusted doses of pdC1-INH. The proportion of laryngeal attacks with re-dosing ranged between 0% and 72%. No re-dosing was needed after treatment with a single body weight-adjusted dose of pdC1-INH (48 attacks). CONCLUSIONS: Available data suggest that among different HAE treatments, body weight-adjusted pdC1-INH (20 U/kg) provides the most reliable treatment response for treatment of laryngeal HAE attacks.

Coagulation Factor XII Gene Mutation in Brazilian Families with Hereditary Angioedema with Normal C1 Inhibitor.

BACKGROUND: Hereditary angioedema (HAE) with normal C1 inhibitor (C1-INH) is a rare disorder. Mutations of the gene encoding coagulation factor XII have been identified in a subset of patients with this condition. Our aim was to investigate mutations in the F12 gene in patients with HAE with normal C1-INH from Brazil. METHODS: We studied 5 Brazilian families with index female patients who presented with recurrent angioedema with normal C1-INH and C4 levels. Genomic DNA was isolated from whole blood and PCR was performed. Mutations were detected by the sequencing of exon 9 of the F12 gene and allelic discrimination. RESULTS: The c.983C>A (p.Thr328Lys) mutation was identified in 16 subjects, from 4 of the 5 families studied, including 8 patients with symptoms of HAE with normal C1-INH (87.5% women) and 8 subjects asymptomatic for HAE (25% women). Mean age at onset of symptoms among the FXII-HAE patients was 13.8 years (range 6-25 years). Recurrent abdominal pain (100%) and subcutaneous angioedema (87.5%) were the most frequent clinical presentations. Two patients presented with associated laryngeal edema. In keeping with previous observations in patients with both C1-INH-HAE and HAE with normal C1-INH, all 7 women with FXII-HAE reported triggering or worsening of symptoms upon intake of estrogen-containing oral contraceptives and/or pregnancy. CONCLUSIONS: We report for the first time in Brazil a mutation in the F12 gene as a likely cause of HAE with normal C1-INH in patients with recurrent attacks of angioedema and/or abdominal pain. A higher frequency of abdominal pain attacks and onset of symptoms at a younger age were observed among Brazilian patients when compared to those from other parts of the world.

Efficacy of C1 esterase inhibitor concentrate in treatment of cutaneous attacks of hereditary angioedema.

BACKGROUND: Although treatment with C1 esterase inhibitor (C1-INH) concentrate is well established for hereditary angioedema (HAE) attacks in general, data that assess its efficacy for cutaneous attack treatment are sparse. OBJECTIVE: To assess efficacy of plasma-derived, nanofiltered C1-INH concentrate for cutaneous attack treatment by comparing treated attacks from the uncontrolled I.M.P.A.C.T.2 study with historical data for untreated attacks. METHODS: Cutaneous attack data from patients with HAE who were treated for cutaneous edema with 20 IU/kg body weight C1-INH concentrate in the uncontrolled I.M.P.A.C.T.2 study (38 patients) were compared with data from untreated patients from an historical data base (46 patients) and included subset analyses for facial edema (treated group, 21 patients; untreated group, 33 patients) and peripheral edema (30 patients in each group). Average attack duration (AAD) per patient was the efficacy end point used to compare treated and untreated patients. Differences were assessed with a Wilcoxon test (primary analysis) and a log-rank test; AAD per patient was analyzed descriptively and graphically with Kaplan-Meier curves. RESULTS: The AAD per patient of all cutaneous attacks or facial and peripheral cutaneous attack subsets was significantly faster with C1-INH treatment than without treatment (Wilcoxon and log-rank tests, both p < 0.0001 for all comparisons). Mean AADs per patient for all, facial, and peripheral attacks were 2.04, 1.45, and 2.16 days, respectively, in the C1-INH-treated group, and were 3.74, 4.45, and 2.98 days, respectively, in the untreated group. Kaplan-Meier curves corroborated the observed group differences. CONCLUSION: Treatment of cutaneous HAE attacks (all attacks or facial and peripheral attack subsets) with 20 IU/kg C1-INH concentrate provided faster attack resolution compared with no treatment.

Icatibant, a new bradykinin-receptor antagonist, in hereditary angioedema.

BACKGROUND: Hereditary angioedema is characterized by recurrent attacks of angioedema of the skin, larynx, and gastrointestinal tract. Bradykinin is the key mediator of symptoms. Icatibant is a selective bradykinin B2 receptor antagonist. METHODS: In two double-blind, randomized, multicenter trials, we evaluated the effect of icatibant in patients with hereditary angioedema presenting with cutaneous or abdominal attacks. In the For Angioedema Subcutaneous Treatment (FAST) 1 trial, patients received either icatibant or placebo; in FAST-2, patients received either icatibant or oral tranexamic acid, at a dose of 3 g daily for 2 days. Icatibant was given once, subcutaneously, at a dose of 30 mg. The primary end point was the median time to clinically significant relief of symptoms. RESULTS: A total of 56 and 74 patients underwent randomization in the FAST-1 and FAST-2 trials, respectively. The primary end point was reached in 2.5 hours with icatibant versus 4.6 hours with placebo in the FAST-1 trial (P=0.14) and in 2.0 hours with icatibant versus 12.0 hours with tranexamic acid in the FAST-2 trial (P<0.001). In the FAST-1 study, 3 recipients of icatibant and 13 recipients of placebo needed treatment with rescue medication. The median time to first improvement of symptoms, as assessed by patients and by investigators, was significantly shorter with icatibant in both trials. No icatibant-related serious adverse events were reported. CONCLUSIONS: In patients with hereditary angioedema having acute attacks, we found a significant benefit of icatibant as compared with tranexamic acid in one trial and a nonsignificant benefit of icatibant as compared with placebo in the other trial with regard to the primary end point. The early use of rescue medication may have obscured the benefit of icatibant in the placebo trial. (Funded by Jerini; ClinicalTrials.gov numbers, NCT00097695 and NCT00500656.)

Treatment with C1-esterase inhibitor concentrate in type I or II hereditary angioedema: a systematic literature review.

Hereditary angioedema (HAE) due to C1 esterase inhibitor (HAE-C1-INH) deficiency is a rare genetic disorder presenting with recurrent episodes of skin swellings, abdominal pain attacks, and potentially fatal laryngeal edema. This study was designed to review the efficacy and safety of pasteurized, human, plasma-derived C1-INH concentrate for the treatment of patients with HAE-C1-INH. A systematic search of electronic databases up to December 2011 was performed without language or date restrictions. Two reviewers completed the study selection using predefined inclusion criteria, tabulated, and analyzed the data. The data were inappropriate for meta-analysis; thus, a qualitative synthesis was performed. We identified 89 studies (≍2000 patients) that investigated C1-INH. Replacement therapy with C1-INH significantly shortened time to onset of symptom relief in HAE attacks compared with placebo in a randomized controlled trial, and similar improvements were consistently reported in observational and descriptive studies, accompanied by improvements in patients' quality of life. C1-INH has been shown to be effective for patients receiving home therapy and short- and long-term prophylaxis. Treatment with C1-INH was generally well tolerated. Administration of C1-INH was not associated with transmission of viruses or development of autoantibodies irrespective of treatment duration. This research provides additional confirmation of the efficacy of C1-INH in the treatment and prevention of HAE attacks. C1-INH is generally safe and well tolerated and has an excellent safety record for over 25 years of clinical use.

Fatal laryngeal attacks and mortality in hereditary angioedema due to C1-INH deficiency.

BACKGROUND: Hereditary angioedema due to C1 inhibitor deficiency (HAE-C1-INH) is characterized by relapsing skin swellings, abdominal pain attacks, and, less frequently, potentially life-threatening laryngeal attacks. OBJECTIVE: This study determined the mortality of patients with and without the diagnosis of HAE-C1-INH and analyzed fatal laryngeal attacks. METHODS: A cohort of 728 patients from 182 families with HAE-C1-INH was evaluated for death cases by analyzing pedigrees. Detailed information on fatal laryngeal attacks in 36 patients was obtained by questioning relatives and treating physicians. RESULTS: Of the 214 patients who had died, 70 asphyxiated during a laryngeal attack. Mortality by asphyxiation was higher in patients with undiagnosed HAE-C1-INH (63 cases) than in patients with diagnosed HAE-C1-INH (7 cases). The lifespan of asphyxiated patients with undiagnosed HAE-C1-INH was on average ∼31 years shorter than patients with undiagnosed HAE-C1-INH who died of other causes. Three phases were distinguished in the fatal laryngeal attacks. Phase 1, the predyspnea phase, lasted on average for 3.7 ± 3.2 hours (range, 0-11 hours). Phase 2, the dyspnea phase, lasted on average for 41 ± 49 minutes (range, 2 minutes to 4 hours). Phase 3, the loss of consciousness phase, lasted on average for 8.9 ± 5.1 minutes (range, 2-20 minutes). CONCLUSIONS: The high mortality in patients with undiagnosed HAE-C1-INH underscores the need to identify these patients and diagnose their condition. The analysis of fatal laryngeal attacks gives further insight into their course, thus helping to avoid fatalities in the future.