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.

PLAUR splicing pattern in hereditary angioedema patients' monocytes and macrophages.

BACKGROUND: The PLAUR gene encodes the urokinase-like plasminogen activator receptor (uPAR) and may undergo alternative splicing. Excluding cassette exons 3, 5 and 6 from the transcript results in truncated protein variants whose precise functions have not been elucidated yet. The PLAUR gene is one of several expressed in myeloid cells, where uPAR participates in different cellular processes, including the contact activation system and kallikrein-kinin system, which play an important role in hereditary angioedema (HAE) pathogenesis. A hypothesis about the PLAUR splicing pattern impact on HAE severity was tested. METHODS AND RESULTS: The RT-PCR quantified by capillary electrophoresis was used. Although no significant difference in alternative transcript frequency was observed between healthy volunteers and HAE patients, a significant increase in all cassette exon inclusion variants was revealed during monocyte-to-macrophage differentiation. CONCLUSIONS: PLAUR alternative splicing in monocytes and macrophages neither was different between HAE patients and healthy controls, nor reflected disease severity. However, the results showed an PLAUR splicing pattern was changing during monocyte-to-macrophage differentiation, but the significance of these changes is unknown and awaits future clarification.

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.

Hereditary Angioedema: Diagnosis, Clinical Implications, and Pathophysiology.

Hereditary angioedema (HAE) is an autosomal dominant disorder caused by a mutation in the C1 esterase inhibitor gene. HAE affects 1/50,000 people worldwide. Three main types of HAE exist: type I, type II, and type III. Type I is characterized by a deficiency in C1-INH. C1-INH is important in the coagulation complement, contact systems, and fibrinolysis. Most HAE cases are type I. Type I and II HAE result from a mutation in the SERPING1 gene, which encodes C1-INH. Formally known as type III HAE is typically an estrogen-dependent or hereditary angioedema with normal C1-INH activity. Current guidelines now recommend subdividing hereditary angioedema with normal C1 esterase inhibitor gene (HAE-nl-C1-INH formerly known as HAE type III) based on underlying mutations such as in kininogen-1 (HAE-KNG1), plasminogen gene (PLG-HAE), myoferlin gene mutation (MYOF-HAE), heparan sulfate-glucosamine 3-sulfotransferase 6 (HS3ST6), mutation in Hageman factor (factor XII), and in angiopoietin-1 (HAE-ANGPT-1). The clinical presentation of HAE varies between patients, but it usually presents with nonpitting angioedema and occasionally abdominal pain. Young children are typically asymptomatic. Those affected by HAE usually present with symptoms in their early 20s. Symptoms can arise as a result of stress, infection, or trauma. Laboratory testing shows abnormal levels of C1-INH and high levels of bradykinin. C4 and D-dimer levels can also be monitored if an acute HAE attack is suspected. Acute treatment of HAE can include IV infusions of C1-INH, receptor antagonists, and kallikrein inhibitors. Short- and long-term prophylaxis can also be administered to patients with HAE. First-line therapies for long-term prophylaxis also include IV infusion of C1-INH. This review aims to thoroughly understand HAE, its clinical presentation, and how to treat it.

[Clinical and genetic studies of a family with hereditary angioedema].

Objective: To diagnose a large family of patients with hereditary angioedema, and to study its inheritance pattern and gene locus. Methods: A retrospective analysis was carried out from August 2021 to February 2022 in a proband (female, 48 years old) and 12 family members who underwent medical history collection and laboratory examinations in the Department of Otorhinolaryngology and Head and Neck Surgery, the Second Hospital of Shanxi Medical University. The clinical data of members and non-affected members [including 7 males and 5 females, aged 12-78 (median 24) years old], were drawn a family map while confirming the diagnosis. Whole exome sequencing technology was used to detect the genetic sequence of the proband and to verify its family members to map the genetic pedigree of the mutation. Results: The inheritance pattern of the family was autosomal dominant, and 8 members of the family were diagnosed with hereditary angioedema by laboratory examination, including 7 cases of type I and 1 case of type Ⅱ. Whole exome sequencing analysis was performed on 2 patients with 2 phenotypes, and it was found that they both carried the same pathogenic mutation locus, which was c.890-2A>G. The family members were verified by next-generation sequencing, and it was found that all members of the family who had a history of edema contained this mutation site, while the younger brother of the proband who had no history of edema did not have this mutation. Conclusion: Both type Ⅰ and type Ⅱ phenotypes are present in this hereditary angioedema family, and the mutation of SERPING1 gene c.890-2A>G causes the onset of each patient in this family.

The Role of Bradykinin Receptors in Hereditary Angioedema Due to C1-Inhibitor Deficiency.

BACKGROUND: Hereditary angioedema (HAE) is a rare, genetic disease caused by the decreased level or function of the C1 inhibitor. The primary mediator of symptoms in HAE is bradykinin acting through its two receptors, namely receptors 1 (BR1) and 2 (BR2). Although BR2 is well characterized, the role of BR1 remains unclear. OBJECTIVE: To study the role of bradykinin receptors 1 (BR1) in the etiopathogenesis of HAE. METHODS: A total of 70 individuals, 40 patients with HAE, and 30 healthy subjects were recruited to the study. HAE was diagnosed in accordance with the international guideline. The level of bradykinin receptors was determined in populations of CD3+, CD4+, CD8+, and CD14++CD16-, CD14++CD16+ monocytes. In addition, the level of disease activity-specific markers was measured. RESULTS: There were statistically significant differences in the subpopulation of lymphocytes and monocytes between patients with HAE compared to healthy subjects. The level of BR1 and BR2 on PBMCs was comparable in healthy subjects and HAE patients during remission with significant overexpression of both receptors, triggered by HAE attack. Moreover, a significant increase in TNF-alpha and IL-1 plasma levels was observed among HAE patients. CONCLUSIONS: BR1 expression may play an important role in the pathomechanism of HAE.

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.

Hereditary angioedema. Diagnosis in an asymptomatic elderly woman / Angioedema hereditario. Diagnóstico en una mujer mayor asintomática

Abstract Hereditary angioedema (HAE) is a rare disease with an autosomal dominant heredity pattern, due to mutations in the gene encoding the C1 esterase inhibitor. The onset of symptoms usually occurs during childhood. Clinically, it is characterized by repeated episodes of angioedema that may affect the skin, abdomen and larynx/pharynx. The occurrence of attacks and their severity are unpredictable and can be fatal without the appropriate treatment. We present the case of an asymptomatic 65-year-old woman, with a history of three adult children diagnosed with HAE. Despite the high probabilities of being a carrier of the mutation, she had not been previously studied. Diagnosis of HAE in a family member would require screening of all at-risk relatives. Early diagnosis is essential to establish a correct and timely therapeutic strategy in order to reduce the morbidity and mortality associated with the disease.

Resumen El angioedema hereditario (HAE) es una enfermedad rara, con un patrón de herencia autosómico dominante, debida a mutaciones en el gen que codifica el inhibidor de la C1 esterasa. El inicio de los síntomas suele ocurrir durante la infancia. Clínicamente se caracteriza por episodios recurrentes de angioedema que pueden afectar la piel, el abdomen y la laringe/faringe. La ocurrencia de los ataques y su gravedad son imprevisibles, y puede resultar fatal sin el tratamiento apropiado. Presentamos el caso de una mujer de 65 años de edad, asintomática, con antecedente de tres hijos adultos con diagnóstico de HAE, quién pese a la alta probabilidad de ser portadora de la mutación, no había sido estudiada previamente. El diagnóstico de HAE en un integrante de la familia obligaría a realizar estudios de cribado en todos los familiares en riesgo. El diagnóstico temprano resulta fundamental para establecer una estrategia terapéutica correcta y oportuna, disminuyendo así la morbimortalidad asociada a la enfermedad.

High Estrogen States in Hereditary Angioedema: a Spectrum.

Sex differences have been well documented within hereditary angioedema (HAE) over the past several decades. Females often experience more frequent and more intense attacks compared to their male counterparts. Additionally, elevated estrogen levels-as seen in pregnancy and use of oral contraceptives-is a widely known trigger for angioedema attacks. In this review article, we will outline how estrogens' downstream effects increase bradykinin, a potent vasodilator and key mediator of HAE. Estrogen-dependent HAE is a rare disorder that provides insight into the relationship between HAE and estrogens. Females affected by this subtype of HAE only experience attacks when under "high estrogen states," such as during pregnancy and when taking exogenous estrogens (most commonly, oral contraceptives). This unique phenotype has been documented in individuals with an activating Factor XII mutation. Thus, based on this clear genotype-phenotype relationship, we conclude that Factor XII may be key in our understanding of estrogens' role in HAE. Lastly, we propose that the sex differences seen in HAE be viewed as a spectrum from exacerbation to underlying genetic mutations in Factor XII.

Screening for Plasminogen Mutations in Hereditary Angioedema Patients.

Hereditary angioedema (HAE) is a rare disease belonging to the group of bradykinin-mediated angioedemas, characterized by recurring edematous episodes involving the subcutaneous and/or submucosal tissues. Most cases of HAE are caused by mutations in the SERPING1 gene encoding C1-inhibitor (C1-INH-HAE); however, mutation analysis identified seven further types of HAE: HAE with Factor XII mutation (FXII-HAE), with plasminogen gene mutation (PLG-HAE), with angiopoietin-1 gene mutation (ANGPT1-HAE), with kininogen-1 gene mutation (KNG1-HAE), with a myoferlin gene mutation (MYOF-HAE), with a heparan sulfate-glucosamine 3-sulfotransferase 6 (HS3ST6) mutation, and hereditary angioedema of unknown origin (U-HAE). We sequenced DNA samples stored from 124 U-HAE patients in the biorepository for exon 9 of the PLG gene. One of the 124 subjects carried the mutation causing a lysine to glutamic acid amino acid exchange at position 330 (K330E). Later, the same PLG mutation was identified in the patient's son. The introduction of new techniques into genetic testing has increased the number of genes identified. As shown by this study, a biorepository creates the means for the ex-post analysis of recently identified genes in stored DNA samples of the patients. This makes the diagnosis more accurate with the possibility of subsequent family screening and the introduction of appropriate therapy.

Hereditary angioedema: a disease seldom diagnosed by pediatricians

Abstract Objectives: To describe the hereditary angioedema to improve awareness of this condition and reduce diagnostic delay. Data sources: Relevant articles in the MEDLINE database through PubMed. Data synthesis: Hereditary angioedema is rare and has an autosomal dominant pattern of inheritance. Its onset occurs mainly in childhood, but there is an important delay in the diagnosis. In the most frequent phenotype, there is a quantitative and/or functional deficiency in the C1esterase inhibitor protein, which regulates the activation of the complement, contact and fibrinolysis systems with greater formation of bradykinin, the main mediator of angioedema. There is a third type, the hereditary angioedema with a normal C1 inhibitor level, which is rare in children. Clinical manifestations are characterized by recurrent angioedema attacks, mainly in the extremities, abdomen and upper airways, which can progress to asphyxia and death. The main triggers are mechanical trauma, infections and stress. The diagnosis is attained by patient clinical picture and decreased serum levels of C4 and C1esterase inhibitor or its function. In hereditary angioedema with a normal C1 inhibitor, there is no change in these parameters, thus requiring a genetic study. Treatment is based on the use of attack medications and long and short-term prophylaxis. Conclusions: Hereditary angioedema is little known by pediatricians due to the significant delay in diagnosis of this condition, whose onset usually begins in childhood. The presence of recurrent angioedema that does not respond to treatment with antihistamines, corticosteroids and adrenaline should increase the diagnostic suspicion.

Unnecessary Abdominal Surgeries in Attacks of Hereditary Angioedema with Normal C1 Inhibitor.

Hereditary angioedema (HAE) is an autosomal dominant disease mostly due to the deficiency of C1 inhibitor (C1-INH). HAE with normal C1-INH was first described in 2000 and associated with mutations in the coagulation factor XII in 2006. Both diseases are associated with high bradykinin production, resulting in increased vascular permeability. Gastrointestinal edema due to HAE can be misdiagnosed as acute abdomen and unnecessary surgical procedures may be performed. The present study evaluates the prevalence of surgical procedures and/or acute abdomen in HAE patients with the coagulation factor XII mutation. It is a retrospective study where patients were diagnosed with recurrent angioedema without urticaria, normal C1-INH levels, and positive family history of angioedema. All patients were evaluated for the known mutations located at exon 9 of the F12 gene. Medical records were evaluated and questionnaires were applied to 52 patients with normal C1-INH levels (age range 13-76 years; 47/52, 90.38% women; 5/52, 9.61% men). F12 mutation was present in 32/52 patients (61.5%). Acute abdominal pain was diagnosed in 16/52 (30.76%) patients, appendicitis in 9/16 (56.2%), and undetermined diagnosis in 7/16 (43.7%). Among patients diagnosed with acute abdominal pain, 13/16 (81.2%) underwent surgery and 3/16 (18.7%) improved without surgical intervention. We conclude that many HAE patients with coagulation factor XII mutation were misdiagnosed with acute abdomen and subjected to unnecessary invasive procedures. It is critical to disseminate information about this rare mutation in patients with otherwise normal C1-INH activity, in order to speed up diagnosis and avoid misconduct.

Treatment of Hereditary Angioedema.

Hereditary angioedema due to C1-esterase inhibitor deficiency (C1-INH-HAE) is a rare autosomal dominant disease. In the last decade, new drugs and new indications for old drugs have played a role in the management of C1-INH-HAE. This review examines current therapy for C1-INH-HAE and provides a brief summary of drugs that are under development. Increased knowledge of the pathophysiology of C1-INH-HAE has been crucial for advances in the field, with inhibition of the kallikrein-kinin system (plasma kallikrein, activated factor XII) as a key area in the discovery of new drugs, some of which are already marketed for treatment of C1-INH-HAE. Pharmacological treatment is based on 3 pillars: treatment of acute angioedema attacks (on-demand treatment), short-term (preprocedure) prophylaxis, and long-term prophylaxis. The 4 drugs that are currently available for the treatment of acute angioedema attacks (purified plasma-derived human C1 esterase inhibitor concentrate, icatibant acetate, ecallantide, recombinant human C1 esterase inhibitor) are all authorized for self-administration, except ecallantide. Purified plasma-derived human C1 esterase inhibitor concentrate is the treatment of choice for short-term prophylaxis. Tranexamic acid, danazol, intravenous and subcutaneous nanofiltered purified plasma-derived human C1 esterase inhibitor concentrate, and lanadelumab can be used for long-term prophylaxis. New drugs are being investigated, mainly as long-term prophylaxis, and are aimed at blocking the kallikrein-kinin system by means of antiprekallikrein, antikallikrein, and anti-activated FXII action.

Angioedema without urticaria: novel findings which must be measured in clinical setting.

PURPOSE OF REVIEW: Angioedema without urticaria is composed of an increasing subtype's variety and presents a challenging diagnosis. This review summarizes the subtypes recently described and subsequent new findings helpful within their classification. RECENT FINDINGS: New methods to measure cleaved high molecular weight kininogen and activated plasma kallikrein have emerged as potential biochemical tests to identify bradykinin-mediated angioedema. Three new subtypes of hereditary angioedema (HAE) with normal C1 inhibitor were described in the past two years: HAE due to mutation in plasminogen gene, in kininogen gene, and in angiopoietin-1 gene; implicating the fibrinolytic and contact systems, and the regulation of vasculature, respectively. The understanding of some mechanisms in angioedema has been improved, compatible to the dominant-negative for some C1 inhibitor variants; furthermore, the increased activation of truncated F12 mutants by plasma kallikrein; and the diminished binding of angiopoietin-1 to its receptor. SUMMARY: The validation of biomarkers for the contact system activation could be beneficial in differentiating bradykinin - from histaminergic-mediated angioedema. Currently, the available laboratorial tests are still somewhat restricted to the evaluation of the complement activation and the mediators of nonhistaminergic and nonbradykinin-mediated angioedema remain to be identified.

Study of angiopoietin and plasminogen genes in hereditary angioedema

SUMMARY OBJECTIVE To investigate the presence of the Angiopoietin 1 (ANGPT1) and Plasminogen (PLG) mutations in patients with Hereditary Angioedema (HAE) and normal C1 esterase inhibitor (C1-INH) levels, who do not harbor the F12 gene mutation. METHODS Patients clinically diagnosed with HAE but without C1-INH deficiency or dysfunction and F12 gene mutation were evaluated. DNA extraction, quantification, and dilution were performed at a concentration of 100 ng/µL, followed by a DNA amplification (PCR) for molecular evaluation of exon 2 of the ANGPT1 gene and exon 9 of the PLG gene for identification of mutations c.807G>T / p.A119S and c.988A>G / p.K330E, respectively. The PCR product was evaluated in 1% agarose gel electrophoresis. Sequencing was performed using the Sanger method. The electropherograms were analyzed using the FASTA® program. RESULTS DNA samples from 15 women were sequenced. Their ages ranged from 10 to 60 years and the normal C1 esterase and C4 inhibitor serum levels ranged from 22 to 39 mg/dL and from 10 to 40 mg/dL, respectively. No mutations were detected in the analyzed exons of ANGPT1 and PLG. However, a single-nucleotide polymorphism (SNP) was detected in two homozygotic and five heterozygotic patients. CONCLUSION Further studies are needed to evaluate these SNPs and scrutinize their potential for use as molecular markers of HAE and as novel therapeutic targets.

RESUMO OBJETIVO Investigar a presença das mutações no gene Angiopoietina (ANGPT1) e gene Plasminogênio (PLG) em pacientes com Angioedema Hereditário (AEH) com inibidor C1 esterase (C1-INH) normal e negativos para mutação do gene F12. MÉTODOS Foram avaliados pacientes com diagnóstico clínico de AEH sem deficiência ou disfunção de C1-INH e negativos para mutação do gene F12. Realizou-se extração, quantificação e diluição do DNA a uma concentração de 100 ng/uL, em seguida amplificação do DNA (PCR) para avaliação molecular do exon 2 do gene ANGPT1 e do exon 9 do gene PLG para identificação das mutações c.807G>T.p.A119S e c.988A>G p.K330E, respectivamente. O produto da PCR foi avaliado em eletroforese em gel de agarose 1%. Foi realizado o sequenciamento pelo método de Sanger. As análises dos eletroferogramas foram realizadas pelo programa FASTA®. RESULTADOS Foram sequenciadas amostras de 15 mulheres, idade entre 10 e 60 anos, com níveis séricos de inibidor de C1 esterase e C4 normais variando de 22 a 39mg/dL e 10 a 40mg/dL, respectivamente. Não foram identificadas mutações nos éxons analisados dos genes ANGPT1 e PLG. Entretanto no gene PLG foram encontrados polimorfismo de nucleotídeo único (SNP), em duas pacientes homozigotas e cinco heterozigotas. CONCLUSÃO Mais estudos sobre SNP são necessários para esclarecer estes achados pois eles podem ser utilizados como marcadores moleculares do AEH e alvo para novos tratamentos.

Hereditary angioedema: Screening of first-degree blood relatives and earlier diagnosis.

Background: Hereditary angioedema (HAE) with C1 inhibitor (C1INH) deficiency is an inherited disease characterized by sudden, recurrent episodes of edema that involve the skin, gastrointestinal tract, respiratory tract, and other organs. Objective: Because it takes a long time from the first symptoms to diagnosis, we aimed to identify HAE in untested first-degree blood relatives among some of our patients with HAE in our outpatient clinic at Hospital Universitário Clementino Fraga (HUCFF), Federal University of Rio de Janeiro. Methods: Untested first-degree relatives of patients with HAE C1INH, even those who were asymptomatic, were identified and invited to participate. Those who agreed to participate answered a specific questionnaire and had a blood sample collected for complement testing. Results: Fifty untested first-degree relatives of 30 index patients with HAE C1INH were identified, and both groups were analyzed. The mean ± standard deviation (SD) age of the index patients group was 37.08 ± 16.56 years (range, 13-73 years), with a high frequency in women (n = 24 [80.0%]). Most of them had severe (n = 23 [76.7%]) and moderate (n = 7 [23.3%]) attacks. None were asymptomatic. The mean ± SD time between the first symptoms and diagnosis was 20.2 ± 11.06 years (range, 0-48 years) in that group. In the first-degree relatives group, 30 new cases of HAE C1INH (60%) were identified. Conclusion: We found that there was a long time between early manifestations and a diagnosis of HAE. First-degree relatives of patients with HAE patients are at risk for having the disease. Sixty percent were newly diagnosed with HAE and with C1INH deficiency in our study. So, screening of family members, including individuals who were asymptomatic, is the key for earlier diagnosis and effective treatment.

THE JEREMIAH METZGER LECTURE NOVEL THERAPEUTIC STRATEGIES OF ALLERGIC AND IMMUNOLOGIC DISORDERS.

Advances in understanding the immunological basis and mechanisms underlying allergic and immunologic disorders have led to effective but costly long-term and repetitive biologic therapies. Gene therapy is a rapidly advancing technology, in which a single administration of an adeno-associated virus encoding the therapeutic protein or monoclonal antibody may provide effective long-term therapy for allergic and immunologic disorders. In this review, we summarize the recent studies from our laboratory developing gene therapy strategies to treat hereditary angioedema and peanut allergy. The unraveling of the pathogenesis of immune-based disorders, including hereditary deficiencies of components of the immune system and allergic disorders, has led to the development of therapies using parenteral administration of recombinant proteins or monoclonal antibodies (1). While many of these therapies are highly effective, they are limited by the half-life of the therapeutic protein or antibody, requiring repetitive administration of days to weeks (2-15). The focus of recent work in our laboratory has been to solve this problem by substituting protein/monoclonal antibody administration with gene therapy, where current technology allows for a single administration of the gene coding for a protein or antibody to provide persistent expression of effective levels of the therapeutic protein or antibody. Gene therapy is a drug delivery platform which uses genetic material, usually in the form of coding exons of the therapeutic gene, to correct, compensate for, or prevent the development of an abnormal phenotype (16). Originally conceptualized as a strategy to treat rare hereditary disorders, gene therapy is being developed for a wide range of human disorders, including common acquired conditions (17-20). In this review, we will describe how we have adopted gene therapy technology to develop therapies for immune-related disorders, using as examples hereditary angioedema, an inherited autosomal dominant disorder, and peanut allergy, a common acquired allergic disorder.

Population pharmacokinetics of subcutaneous C1-inhibitor for prevention of attacks in patients with hereditary angioedema.

BACKGROUND: Long-term prophylaxis with subcutaneous (SC) administration of a highly concentrated plasma-derived C1-esterase inhibitor (C1-INH) formulation was recently approved by the Food and Drug Administration for hereditary angioedema (HAE) attack prevention. OBJECTIVE: To characterize the population pharmacokinetics of C1-INH (SC) (HAEGARDA® ; CSL Behring) in healthy volunteers and HAE patients, and assess the variability and influence of covariates on pharmacokinetics. METHODS: C1-INH functional activity data obtained after administration of various C1-INH (intravenous; IV) and C1-INH (SC) doses from 1 study in healthy volunteers (n = 16) and 2 studies in subjects with HAE (n = 108) were pooled to develop a population pharmacokinetic model (NONMEM v7.2). Pharmacokinetic parameters derived from steady-state simulations based on the final model were also evaluated. RESULTS: C1-INH functional activity following C1-INH (SC) administration was described by a linear one-compartment model with first-order absorption and elimination, with inter-individual variability in all parameters tested. The mean population bioavailability of C1-INH (SC), and pharmacokinetic parameters for clearance (CL), volume of distribution, and absorption rate were estimated to be ~43%, 1.03 mL/hour/kg, 0.05 L/kg and 0.0146 hour-1 , respectively. The effect of bodyweight on CL of C1-INH functional activity was included in the final model, estimated to be 0.74. Steady-state simulations of C1-INH functional activity vs time profiles in 1000 virtual HAE patients revealed higher minimum functional activity (Ctrough ) levels after twice-weekly dosing with 40 IU/kg (~40%) and 60 IU/kg (~48%) compared with 1000 IU IV (~30%). Based on the population pharmacokinetic model, the median time to peak concentration was ~59 hours and the median apparent plasma half-life was ~69 hours. CONCLUSIONS AND CLINICAL RELEVANCE: Twice-weekly bodyweight-adjusted dosing of C1-INH (SC) exhibits linear pharmacokinetics and dose-dependent increases in Ctrough levels at each dosing interval. In this analysis, SC dosing led to maintenance of higher Ctrough levels than IV dosing.

The complex alteration in the network of IL-17-type cytokines in patients with hereditary angioedema.

Hereditary angioedema (HAE) is a rare autosomic-dominant disorder characterized by a deficiency of C1 esterase inhibitor which causes episodic swellings of subcutaneous tissues, bowel walls and upper airways that are disabling and potentially life-threatening. We evaluated n = 17 patients with confirmed HAE diagnosis during attack and remission state and n = 19 healthy subjects. The samples were tested for a panel of IL (Interleukin)-17-type cytokines (IL-1ß, IL-6, IL-10, granulocyte-macrophage colony stimulating factor (GM-CSF), IL-17, IL-21, IL-22, IL-23) and transforming growth factor-beta (TGF-ß) subtypes. Data indicate that there are variations of cytokine levels in HAE subjects comparing the condition during the crisis respect to the value in the remission phase, in particular type 17 signature cytokines are increased, whereas IL-23 is unmodified and TGF-ß3 is significantly reduced. When comparing healthy and HAE subjects in the remission state, we found a significant difference for IL-17, GM-CSF, IL-21, TGF-ß1 and TGF-ß2 cytokines. These results confirm and extend our previous findings indicating that in HAE there is operating an inflammatory activation process, which involves also T helper 17 (Th17) cytokines and TGF-ß isoforms, associated with localized angioedema attacks and characterized by elevated bradykinin levels.

Coagulation factor XII in thrombosis and inflammation.

Combinations of proinflammatory and procoagulant reactions are the unifying principle for a variety of disorders affecting the cardiovascular system. The factor XII-driven contact system starts coagulation and inflammatory mechanisms via the intrinsic pathway of coagulation and the bradykinin-producing kallikrein-kinin system, respectively. The biochemistry of the contact system in vitro is well understood; however, its in vivo functions are just beginning to emerge. Challenging the concept of the coagulation balance, targeting factor XII or its activator polyphosphate, provides protection from thromboembolic diseases without interfering with hemostasis. This suggests that the polyphosphate/factor XII axis contributes to thrombus formation while being dispensable for hemostatic processes. In contrast to deficiency in factor XII providing safe thromboprotection, excessive FXII activity is associated with the life-threatening inflammatory disorder hereditary angioedema. The current review summarizes recent findings of the polyphosphate/factor XII-driven contact system at the intersection of procoagulant and proinflammatory disease states. Elucidating the contact system offers the exciting opportunity to develop strategies for safe interference with both thrombotic and inflammatory disorders.