Factor VII activating protease (FSAP) is not essential in the pathophysiology of angioedema in patients with C1 inhibitor deficiency.

BACKGROUND: Excessive bradykinin (BK) generation from high molecular weight kininogen (HK) by plasma kallikrein (PK) due to lack of protease inhibition is central to the pathophysiology of hereditary angioedema (HAE). Inadequate protease inhibition may contribute to HAE through a number of plasma proteases including factor VII activating protease (FSAP) that can also cleave HK. OBJECTIVE: To investigate the interaction between FSAP and C1 inhibitor (C1Inh) and evaluate the potential role of FSAP in HAE with C1Inh deficiency. MATERIALS AND METHODS: Plasma samples from 20 persons with HAE types 1 or 2 in remission were studied and compared to healthy controls. We measured and compared antigenic FSAP levels, spontaneous FSAP activity, FSAP generation potential, activation of plasma pre-kallikrein (PPK) by FSAP, and the formation of FSAP-C1Inh and FSAP-alpha2-antiplasmin (FSAP-α2AP) complexes. Furthermore, we measured HK cleavage and PK activation after activation of endogenous pro-FSAP and after addition of exogenous FSAP. RESULTS: In plasma from HAE patients, there is increased basal FSAP activity compared to healthy volunteers. HAE plasma exhibits decreased formation of FSAP-C1Inh complexes and increased formation of FSAP-α2AP complexes in histone-activated plasma. Although exogenous FSAP can cleave HK in plasma, this was not seen when endogenous plasma pro-FSAP was activated with histones in either group. PK was also not activated by FSAP in plasma. CONCLUSION: In this study, we established that FSAP activity is increased and the pattern of FSAP-inhibitor complexes is altered in HAE patients. However, we did not find evidence suggesting that FSAP contributes directly to HAE attacks.

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.

How do patients and physicians communicate about hereditary angioedema in the United States?

BACKGROUND: Hereditary angioedema (HAE) is a rare disease that manifests as recurrent and debilitating angioedema attacks, significantly impacting patients' quality of life. OBJECTIVE: To assess communication dynamics between patients with HAE and treating physicians and the impact this has on the treatment of HAE in the United States. METHODS: This observational study used an institutional review board-approved protocol to collect four sources of patient-physician communication data from the period between January 2015 and May 2017: in-office conversations between patients aged ≥18 years with HAE and physicians, follow-up dictations with physicians, telephone interviews with patients and physicians, and publicly available social media posts from patients. Participant language was qualitatively assessed and key communication elements and communication gaps identified. RESULTS: Twenty-five in-office conversations, 14 follow-up physician dictations, and 17 telephone interviews were conducted with a total of 29 unique patients, 4 caregivers, and 14 physicians. In-office conversations were generally physician-driven and focused primarily on symptom frequency, location, and severity; lexicon from both parties centered on "episodes" and "swelling." During visits, impact on quality of life was not routinely assessed by physicians nor discussed proactively by patients; however, during telephone interviews and online, patients frequently described the multifaceted burden of HAE. Patients highlighted the difficulties they experience by using repetition, emphasis, and metaphors; they also varied the descriptors used for attacks depending on the communication goal. Physicians used intensifiers to emphasize the necessity of rescue medication access, whereas prophylactic treatments were positioned as an option for frequent or laryngeal attacks. CONCLUSION: Vocabulary differences suggest that the full impact of HAE is not consistently communicated by patients to physicians during clinical visits, indicating the potential for misaligned understanding of disease burden. A patient-driven, rather than physician-driven approach to the discussions may elicit valuable information that could help to optimize treatment approaches.

Effect of COVID-19 on hereditary angioedema activity and quality of life.

Background: The demonstration that severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) enters the cell via the angiotensin-converting enzyme 2 receptor has raised concerns that, in hereditary angioedema (HAE), a disease characterized by bradykinin-mediated angioedema attacks, coronavirus disease 2019 (COVID-19) may trigger angioedema attacks, increase the frequency and/or severity of attacks, or cause more severe symptoms of COVID-19. Objective: The objective was to evaluate the severity of COVID-19 in patients with HAE, the course of HAE attacks, angioedema activity, and the quality-of-life scores during COVID-19 pandemic. Methods: Patients diagnosed with HAE for at least 6 months were included in the study. The 7-day Angioedema Activity Score and the Angioedema Quality of Life (AE-QoL) Questionnaire were first completed at the onset of the pandemic between March 12 and June 1, 2020, then during SARS-CoV-2 infection, and in the third month after recovering from COVID-19. Results: Ten of 67 patients with HAE (14.9%) were diagnosed with COVID-19. The median (interquartile range) age of the 10 patients diagnosed with COVID-19 was 35.5 years (28.0-55.0 years). Six of the 10 patients (60%) were women. During COVID-19, five of the 10 patients (50%) had no angioedema attack. Two patients with severe HAE experienced a significant increase in angioedema activity during COVID-19 compared with their basal activity scores. The remaining three patients had a similar or lower attack frequency than their basal level. Four (40%) of the 10 patients had a relative increase in their attacks during the convalescence period. There was no statistically significant difference among pre-COVID-19, during COVID-19 and post-COVID-19 periods in function, mood, fear and/or shame, nutrition, and total scores of the AE-QoL Questionnaire although the fear dimension was relatively more affected (p = 0.06). Conclusion: Although the sample size was small, analysis of our data supported that the symptoms of COVID-19 were not more severe in HAE. Also, there was no significant difference in the AE-QoL Questionnaire scores, the frequency, and severity of angioedema attacks during the course of COVID-19 in the patients with HAE.

A novel murine in vivo model for acute hereditary angioedema attacks.

Hereditary Angioedema (HAE) is a rare genetic disease generally caused by deficiency or mutations in the C1-inhibitor gene, SERPING1, a member of the Serpin family. HAE results in acute attacks of edema, vasodilation, GI pain and hypotension. C1INH is a key inhibitor of enzymes controlling complement activation, fibrinolysis and the contact system. In HAE patients, contact system activation leads to uncontrolled production of bradykinin, the vasodilator responsible for the characteristic symptoms of HAE. In this study, we present the first physiological in vivo model to mimic acute HAE attacks. We evaluate hypotension, one of the many hallmark symptoms of acute HAE attacks using Serping1 deficient mice (serping1-/-) and implanted telemetry. Attacks were induced by IV injection of a silica nanoparticle (SiNP) suspension. Blood pressure was measured in real time, in conscious and untethered mice using implanted telemetry. SiNP injection induced a rapid, reversible decrease in blood pressure, in the presence of angiotensin converting enzyme (ACE) inhibition. We also demonstrate that an HAE therapeutic, ecallantide, can prevent HAE attacks in this model. The in vivo murine model described here can facilitate the understanding of acute HAE attacks, support drug development and ultimately contribute to improved patient care.

Therapeutic management of hereditary angioedema: past, present, and future.

Hereditary angioedema is a rare disease that can often be disabling or even life threatening because of the unpredictable, self-limiting, and localized swelling episodes involving cutaneous, subcutaneous, and mucosal sites. The last decades revealed a spectrum of possibilities to control the disease through the development of effective therapies that changed the life of many patients and families worldwide. This review summarizes the current literature regarding the general management and therapeutic approach in patients with hereditary angioedema, both with and without C1 inhibitor deficiency. Medications already available in the market and new drugs in different research stages of development are addressed. Recent decades saw a huge leap in identifying mechanisms of angioedema and developing modern safe and effective medications to both treat acute angioedema manifestations and control disease activity via prophylactic therapy. Further improvement is still needed, together with improving global accessibility of diagnostic tools and effective medications. Whether novel drugs will demonstrate a sustained cost/effectiveness ratio will be answered in the years to come when we will witness whether a majority of the patients will benefit from these major advances.

Angioedema without wheals: a clinical update.

Angioedema without wheals (urticaria) represents a heterogeneous group of clinically indistinguishable diseases of hereditary or acquired etiology. Hereditary angioedema is a rare inherited condition leading to recurrent, sometimes life-threatening angioedema attacks in subcutaneous tissues and gastrointestinal and oropharyngeal mucosa dating back to childhood or adolescence. Most of these patients have mutations in the SERPING1 gene, causing either low C1 inhibitor production (hereditary angioedema with C1 inhibitor deficiency type I) or the production of dysfunctional C1 inhibitor (hereditary angioedema with C1 inhibitor deficiency type II). Hereditary angioedema with normal C1 inhibitor has been defined later. Although C1 inhibitor concentration and function are in the normal range, it leads to typical hereditary angioedema symptoms owing to mutations in FXII, PLG, ANGPT1, KNG1, and MYOF genes. Patients who exhibit none of these genetic mutations despite having a similar clinical presentation are classified as having unknown hereditary angioedema. Fewer than 1 in 10 patients with C1 inhibitor deficiency have acquired angioedema with C1 inhibitor deficiency. The clinical presentation is very similar to that of hereditary angioedema, making it difficult to distinguish these 2 conditions clinically. Unlike hereditary angioedema, there are no genetic mutations, and family history and symptoms tend to appear later in life. Acquired angioedema with C1 inhibitor deficiency is commonly associated with lymphoproliferative and autoimmune diseases. Angioedema attacks might start 1 year before the underlying disease in acquired angioedema with C1 inhibitor deficiency. Approximately half of the patients admitted to the hospital for acute angioedema are patients receiving angiotensin-converting enzyme (ACE) inhibitor therapy. Angioedema typically occurs on the lips, tongue, mouth, pharynx, and subglottic regions. Patients may require hospitalization and intensive care monitoring owing to airway involvement. Idiopathic histaminergic acquired angioedema may be diagnosed only when any possible causes of histaminergic angioedema are excluded (foods, drugs, animal dander, aeroallergens, insect stings, latex, and others), and the symptoms respond well to antihistamine treatment. Idiopathic nonhistaminergic acquired angioedema should be considered when all other types of recurrent angioedema have been ruled out and patients do not respond to high-dose antihistamines. The lack of a standard biochemical laboratory test for patients with idiopathic histaminergic acquired angioedema, idiopathic nonhistaminergic acquired angioedema, angiotensin-converting enzyme inhibitor-induced acquired angioedema, and hereditary angioedema with normal C1 inhibitor makes the diagnosis more challenging. Future efforts should focus on increasing awareness of all the rare types of angioedema among physicians and developing more straightforward and more accessible diagnostic methods.

Quality of life in patients with hereditary angioedema in Canada.

BACKGROUND: Hereditary angioedema (HAE) is associated with decreased quality of life (QoL), which has typically been measured using a generic non-disease-specific questionnaire. OBJECTIVE: We aimed to assess the QoL in patients with HAE type I and II in Canada using a previously validated HAE-specific questionnaire. METHODS: An online questionnaire was sent to the members of two Canadian HAE patient groups to collect data on demographics, HAE clinical course, and QoL scores. All patients 18 years of age or older with HAE type I or II were eligible. The impact of the available clinical factors on the QoL scores was evaluated. Multiple linear regression was performed using clinically relevant factors to predict HAE QoL outcome. RESULTS: Among the 72 patients in the study, the mean total HAE QoL score was 102 (±23) (SD) on a scale of 25 to 135, with higher scores indicating better QoL. Although the total QoL scores correlated positively with patients' level of satisfaction and perceived control (P < .001 for both), it correlated negatively with the number of acute attacks (P = .03). Yet, the types of treatment did not have an impact on the QoL. Predictors, including sex, comorbidities, and the number of attacks, only explained 12% of the variance in the total QoL scores. CONCLUSION: HAE continues to impair QoL in Canadian patients despite receiving recommended treatment. Although the frequency of attacks affects QoL, patients' experience with their HAE care also affects QoL substantially. The study highlights the importance of considering patients' experience with their HAE care as physicians develop an appropriate management plan.

Pathophysiology and underlying mechanisms in hereditary angioedema.

This review aims to summarize the main pathophysiological events involved in the development of hereditary angioedema (OMIM#106100). Hereditary angioedema is a rare genetic disease inherited in an autosomal dominant manner and caused by a loss of control over the plasma contact system or kallikrein-kinin system, which results in unrestrained bradykinin generation or signaling. In patients with hereditary angioedema, BK binding to endothelial cells leads to recurrent episodes of swelling at subcutaneous or submucosal tissues that can be life threatening when affecting the upper respiratory tract. The disease can either present with hypocomplementemia owing to the presence of pathogenic variants in the gene encoding complement C1 inhibitor (hereditary angioedema with C1-inhibitor deficiency) or present with normocomplementemia and associate with elevated estrogen levels owing to gain-of-function variants in the genes encoding coagulation proteins involved in the kallikrein-kinin system (namely, coagulation FXII [FXII-associated hereditary angioedema], plasminogen [PLG-associated hereditary angioedema], and high-molecular-weight kininogen [KNG1-associated hereditary angioedema]). Moreover, in recent years, novel pathogenic variants have been described in the genes encoding angiopoietin 1 (ANGPT1-associated hereditary angioedema) and myoferlin (MYOF-associated hereditary angioedema), which further expand the pathophysiological picture of hereditary angioedema.

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

El angioedema hereditario por déficit del inhibidor de la C1 esterasa (AEH-C1-INH) es una enfermedad rara hereditaria autosómica dominante.En la última década nuevos fármacos y nuevas indicaciones de antiguos fármacos han llegado al área del AEH-C1-INH. En esta revisión se valora el conjunto de fármacos disponibles para el AEH-C1-INH, junto con los fármacos en desarrollo. Los avances en el conocimiento de la fisiopatología del AEH-C1-INH han sido fundamentales para este desarrollo, con la inhibición del sistema de calicreína-cininas (calicreína plasmática, factor XII activado) como un punto caliente para el descubrimiento de nuevos fármacos, algunos de los cuales ya han llegado al mercado del AEH-C1-INH.El tratamiento farmacológico se basa en tres pilares: tratamiento de los ataques agudos de angioedema (tratamiento a demanda), profilaxis a corto plazo o preprocedimiento, profilaxis a largo plazo.Hay actualmente 4 fármacos disponibles para el tratamiento de los ataques agudos de angioedema (concentrado plasmático purificado nanofiltrado del inhibidor de la C1 esterasa humana, acetato de icatibant, ecalantida, inhibidor recombinante de la C1 esterasa humana), todos ellos autorizados para autoadministración, excepto la ecalantida.El concentrado plasmático del inhibidor de la C1 esterasa humana es el tratamiento de elección como profilaxis a corto plazo.Como profilaxis a largo plazo se puede utilizar ácido tranexámico, danazol, concentrado plasmático del inhibidor de la C1 esterasa humano intravenoso y subcutáneo y lanadelumab.Se están investigando nuevos fármacos, fundamentalmente como profilaxis a largo plazo, dirigidos a bloquear el sistema calicreína cininas con acción anti precalicreína, anti calicreína y anti FXII activado

Hereditary angioedema: Pathophysiology (HAE type I, HAE type II, and HAE nC1-INH).

The pathophysiology of hereditary angioedema (HAE) in virtually all cases is the result of the uncontrolled production of the vasoactive peptide bradykinin. C1 inhibitor (C1-INH) is a serine protease inhibitor, which, under normal circumstances, is the regulator of critical enzymes that are active in the cascades that result in bradykinin generation. In the classic forms of HAE, C1-INH is not produced in sufficient quantities (<40% of normal) or the function is <40% of normal activity. The major pathway for the production of bradykinin is the "contact system," also known as the kallikrein-kinin system. This system begins with the activation of factor XII (FXII) to FXIIa, by a variety of physiologic and pathologic stimuli. FXIIa is a serine protease that binds to surfaces and cleaves prekallikrein to the active serine protease kallikrein. Kallikrein then cleaves high-molecular-weight kininogen to release the nonapeptide bradykinin. Bradykinin binds to the bradykinin ß2 receptor, which increases vascular permeability and allows the flow of fluids into the extracellular space and results in angioedema. The two major enzymes generated in this cascade FXIIa and kallikrein are inhibited by C1-INH, which is the major regulator of this cascade. Failure to adequately control the production of bradykinin is thus the major mechanism for HAE. Several other types of HAE in which C1-INH is not decreased (HAE nlC1-INH) have been described. The alterations in FXII and plasminogen (also a serine protease inhibited by C1-INH) like with classic HAE are the result of dysregulation of bradykinin generation. Only genetic alterations in angiopoietin-1 may not be related to bradykinin generation, rather related to the control of the effect of bradykinin on the vascular endothelium.

Clinical presentation of hereditary angioedema.

Hereditary angioedema (HAE) is a rare, autosomal dominant disease caused by a deficiency in the C1-inhibitor protein. It is characterized by recurrent episodes of nonpruritic, nonpitting, subcutaneous or submucosal edema that typically involves the extremities or the gastrointestinal tract. However, the genitourinary tract, face, oropharynx, and/or larynx may be affected as well. Symptoms often begin in childhood, worsen at puberty, and persist throughout life, with unpredictable severity. Patients who are untreated may have frequent attacks, with intervals that can range from every few days to rare episodes. Minor trauma and stress are frequent precipitants of swelling episodes, but many attacks occur without clear triggers. HAE attacks may be preceded by a prodrome and/or be accompanied by erythema marginatum. The swelling typically worsens over the first 24 hours, before gradually subsiding over the subsequent 48 to 72 hours. Although oropharyngeal swelling is less frequent, more than half of patients have had at least one episode of laryngeal angioedema during their lifetime. Attacks may start in one location and spread to another before resolving. HAE attacks that involve the abdomen or oropharynx have been associated with significant morbidity and mortality. Abdominal attacks can cause severe abdominal pain, nausea, and vomiting. Bowel sounds are often diminished or silent, and guarding and rebound tenderness may be present on physical examination. These findings may lead to unnecessary abdominal imaging and procedures. Fluid shifts into the interstitial space or peritoneal cavity can cause clinically significant hypotension. Laryngeal edema poses the greatest risk for patients with HAE. Although prompt diagnosis and treatment improves outcomes, the variable presentation of HAE can make it difficult to diagnose.

C1-inhibitor Deficiency Induces Myositis-like Symptoms Via the Deposition of the Membrane Attack Complex in the Muscle.

We herein report a 56-year-old Japanese woman who had been diagnosed with hereditary angioedema. She experienced progressing muscle weakness and pain in the upper and lower extremities. Blood tests revealed a marked increase in creatine kinase levels; however, myositis-specific autoantibodies were not detected. Serum C1-inhibitor activity and C4 levels were low. A muscle biopsy showed mild muscle fiber necrosis and C5b-9 deposition in the endomysial capillary vessel walls and sarcolemma, mimicking necrotizing myopathy. These results suggest that C1-inhibitor deficiency induces myositis-like symptoms through the activation of the complement pathway and deposition of the membrane attack complex in the muscles.

Life-threatening laryngeal attacks in hereditary angioedema patients.

BACKGROUND: Hereditary angioedema due to C1-inhibitor deficiency (HAE-C1INH) is a rare genetic disease that runs in the family. As a result of the disease, acute swellings of the subcutaneous tissue and mucous membranes of the digestive and respiratory systems, including the larynx, occur. Any attack of the disease involving the throat and larynx is particularly dangerous and requires knowledge of clinical determinants of the disease and its proper management. MATERIALS AND METHODS: The study included adult consecutive HAE-C1INH patients having follow-up visits in our centre. The group was examined with a structured clinical questionnaire, concerning the last 6 months and focusing particularly on laryngeal swelling attacks. RESULTS: 55 subjects (F/M - 35/20, age range - 18-76) were included in the study. Laryngeal attacks occurred in 19 individuals (34.5%): 1-3, 4-6, and ≥7 attacks in 9, 8 and 2 patients, respectively, two of whom required intubation. In comparison to other patients, subjects with laryngeal attacks were characterised by significantly more frequent: (1) facial attacks, (2) severe disease activity, (3) the occurrence of female patients, (4) mental stress as a trigger of attacks. All patients with laryngeal attacks had a rescue medication at home and 15/19 (78%) patients could use it at home. Most of them used plasma-derived C1-inhibitor 17/19 (89.5%) and icatibant, 8/19 (42.1%). DISCUSSION: HAE-C1INH patients with laryngeal attacks require particular attention. Proper training regarding the identification of these patients, adequate management, access to emergency services and emergency drugs are essential to ensure the safety of subjects with this localization of HAE-C1INH attacks.