Hereditary and acquired complement component 1 esterase inhibitor deficiency: a review for the hematologist

Epidemiology, economic, and humanistic burden of hereditary angioedema: a systematic review

BACKGROUND

This systematic study aims to assess the global epidemiologic, economic, and humanistic burden of illness associated with all types of hereditary angioedema.

METHODS

A systematic search for articles reporting the epidemiologic, economic, and humanistic burden associated with patients with HAE was conducted using English and Chinese literature databases from the inception to May 23, 2022. The selected studies were assessed for their quality and risk of bias. The study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses and registered with the International Prospective Register of Systematic Reviews (PROSPERO; CRD42022352377).

RESULTS

In total, 65 articles that met the search inclusion criteria reported 10,310 patients with HAE, of whom 5861 were female patients. Altogether, 4312 patients (81%) and 479 patients (9%) had type 1 and type 2 HAE, respectively, whereas 422 patients (8%) had HAE-normal C1-INH. The overall prevalence of all types of HAE was between 0.13 and 1.6 cases per 100,000. The mean or median delay from the first onset of a symptom of HAE to confirmed diagnosis ranged from 3.9 to 26 years. The estimated risk of death from asphyxiation was 8.6% for patients with HAE. Hospitalization, medication, unnecessary surgeries, doctor visits, specialist services, and nursing costs are direct expenses that contribute to the growing economic burden. The indirect cost accounted mostly due to missing work ($3402/year) and loss of productivity ($5750/year). Furthermore, impairment of QoL as reported by patient-reported outcomes was observed. QoL measures identified depression, anxiety, and stress to be the most common symptoms for adult patients and children.

CONCLUSION

This study highlights the importance of early diagnosis and the need for improving awareness among health care professionals to reduce the burden of HAE on patients and society.

Patient-physician interactions in hereditary angioedema-Key learnings from the coronavirus disease 2019 pandemic

BACKGROUND

The coronavirus disease pandemic and its containing measures have caused concerns for patients with hereditary angioedema (HAE) and their treating physicians. Both faced challenges surrounding interaction, and communication had to adapt to facilitate appropriate management. Specifically, the pandemic resulted in reduced in-person contact in clinics. Where possible, telemedicine appointments were offered and treatment outside the hospital setting was encouraged. BODY: The pandemic markedly affected patient-physician communication, which is essential to maintain partnerships and optimize care. Although patients with HAE are often experts in their condition, guidance by their physicians is essential, especially with the recent shift toward patient-centered management for rare diseases and shared decision-making (SDM). SDM enables patients to take control of their disease and allows the risks and benefits of treatment to be discussed with their physicians. This review explores perspectives from patients and physicians in the HAE clinical setting, particularly regarding their experiences with communication throughout the pandemic. We discuss the importance of SDM in rare diseases such as HAE, factors that impact effective communication, and potential solutions.

CONCLUSION

Since patient-centered care and SDM have particular relevance in rare diseases in general, we believe our findings could be transferrable and applicable in the management of other rare diseases.

Complement therapeutics are coming of age in rheumatology

The complement system was described over 100 years ago, and it is well established that activation of this pathway accompanies the great majority of autoimmune and inflammatory diseases. In addition, over three decades of work in murine models of human disease have nearly universally demonstrated that complement activation is upstream of tissue injury and the engagement of pro-inflammatory mechanisms such as the elaboration of cytokines and chemokines, as well as myeloid cell recruitment and activation. With that background, and taking advantage of advances in the development of biologic and small-molecule therapeutics, the creation and clinical evaluation of complement therapeutics is now rapidly expanding. This article reviews the current state of the complement therapeutics field, with a focus on their use in diseases cared for or consulted upon by rheumatologists. Included is an overview of the activation mechanisms and components of the system, in addition to the mechanisms by which the complement system interacts with other immune system constituents. The various therapeutic approaches to modulating the system in rheumatic and autoimmune diseases are reviewed. To understand how best to clinically assess the complement system, methods of its evaluation are described. Finally, next-generation therapeutic and diagnostic advances that can be envisioned for the future are discussed.

Isolated Angioedema: A Review of Classification and Update on Management

OBJECTIVE

The purpose of this article is to review the various types of angioedema including diagnosis and treatment.

DATA SOURCES

PubMed search of articles in the English language various types of angioedema STUDY SELECTION: Articles on the subject matter were selected and reviewed.

RESULTS

Herein, a case based approach is presented for discussing the major types of angioedema including: hereditary angioedema (HAE) TypesI/II and normal complement, acquired angioedema, Angiotensin converting enzyme (ACE) induced angioedema, as well as histaminergic and non-histaminergic angioedema. Emerging treatments of HAE including targets of pre-kalikrein, DNA vector technology replacing C1INH protein, and CRIPSR technology targeting PKK among many others are explored. In addition, other causes as well as mimickers of angioedema are briefly reviewed. Finally, a novel algorithm is proposed to help guide the treating physician through the work up and management of patients with suspected idiopathic angioedema unresponsive to conventional therapy with antihistamines.

CONCLUSION

Over the years, many strides have been made in both understanding the pathophysiology of various types of angioedema as well as expansion of treatment options. It is important for clinicians to be aware of current and emerging treatment options. We provide a novel practical algorithm to guide clinicians in challenging cases of idiopathic angioedema refractory to antihistamines.

Acquired C1-inhibitor deficiency due to splenic marginal zone lymhoma: Case Report

We present the case of a 67-year-old woman who suffered recurrent episodes of angioedema of the face and larynx. After thorough biochemical investigations, an acquired deficiency of C1-INH was suspected. To evaluate a potential underlying malignancy, a whole-body FDG-PET/CT was performed and showed solely a marked splenomegaly pointing towards a splenic marginal zone lymphoma, which was confirmed by pathological examination.With this case, we discuss the pathophysiology, diagnosis and management of recurrent acquired angioedema attacks as the first presentation of an underlying lymphoproliferative disease.

C1-Inhibitor: Structure, Functional Diversity and Therapeutic Development

Human C1-Inhibitor (C1INH), also known as C1-esterase inhibitor, is an important multifunctional plasma glycoprotein that is uniquely involved in a regulatory network of complement, contact, coagulation, and fibrinolytic systems. C1INH belongs to a superfamily of serine proteinase inhibitor (serpins) and exhibits its inhibitory activities towards several target proteases of plasmatic cascades, operating as a major anti-inflammatory protein in the circulation. In addition to its inhibitory activities, C1INH is also involved in non-inhibitory interactions with some endogenous proteins, polyanions, cells and infectious agents. While C1INH is essential for multiple physiological processes, it is better known for its deficiency with regards to Hereditary Angioedema (HAE), a rare autosomal dominant disease clinically manifested by recurrent acute attacks of increased vascular permeability and edema. Since the link was first established between functional C1INH deficiency in plasma and HAE in the 1960s, tremendous progress has been made in the biochemical characterization of C1INH and its therapeutic development for replacement therapies in patients with C1INH-dependent HAE. Various C1INH biological activities, recent advances in the HAE-targeted therapies, and availability of C1INH commercial products have prompted intensive investigation of the C1INH potential for treatment of clinical conditions other than HAE. This article provides an updated overview of the structure and biological activities of C1INH, its role in HAE pathogenesis, and recent advances in the research and therapeutic development of C1INH; it also considers some trends for using C1INH therapeutic preparations for applications other than angioedema, from sepsis and endotoxin shock to severe thrombotic complications in COVID-19 patients.

Bradykinin-Mediated Angioedema: An Update of the Genetic Causes and the Impact of Genomics

Recurrent episodes of bradykinin-mediated angioedema (Bk-AE) can associate with acquired or hereditary conditions, the former most commonly developing secondarily to a pharmacological treatment. Despite successful genomic advances that have led to the identification of a large number of disease genes irrespective of disease prevalence, their application to Bk-AE has barely occurred. As a consequence, the genetic causes of Bk-AE remain poorly understood, obstructing the identification of patient subtypes and the development of precision medicine strategies. This review provides an update of the genetic studies completed to date on the acquired forms, which have almost exclusively focused on Bk-AE secondarily to the angiotensin-converting enzyme inhibitor treatment, and the blooming subdivision of the hereditary forms established by the identification of novel causal genes with next-generation sequencing (NGS) technology-based exome studies in genetically undiagnosed patients. Finally, based on the diverse benefits that are offered by the technology, we present arguments favoring the use of holistic NGS approaches as first-tier genetic tests as a promise to reduce the diagnostic odyssey of patients with suspected hereditary forms of Bk-AE.

Real-world outcomes in hereditary angioedema: first experience from the Icatibant Outcome Survey in the United Kingdom

Background

Hereditary angioedema (HAE) is a potentially life-threatening, bradykinin-mediated disease, often misdiagnosed and under-treated, with long diagnostic delays. There are limited real-world data on best-practice management of HAE in the UK.

Objectives

To characterize the clinical profile, management and outcomes of patients with HAE type I and II from three specialist centres in the UK using data from the Icatibant Outcome Survey (IOS; Shire, Zug, Switzerland), an international observational study monitoring safety and effectiveness of icatibant, a selective bradykinin B2 receptor antagonist.

Methods

We performed retrospective analyses of IOS data for patients with HAE type I and II from three centres in the UK and compared UK data with pooled IOS data from 10 countries (48 centres).

Results

Analyses included 73 UK and 579 non-UK patients with HAE type I or II. Median diagnostic delay was 6.2 and 5.9 years, respectively. Analysis of data collected from February 2008 to July 2016 included 286 icatibant-treated attacks in 58 UK patients and 2553 icatibant-treated attacks in 436 non-UK patients (median of 3.0 attacks per patient in both groups). More attacks were treated by icatibant self-administration in UK patients (95.8%) than in non-UK patients (86.8%, p < 0.001). Time to icatibant treatment, time to resolution and attack duration were not significantly different in the UK versus non-UK patients.

Conclusion

UK patients from the specialist centres studied report similar diagnostic delay and similar icatibant treatment outcomes to their non-UK counterparts. However, improvements in the timely diagnosis of HAE are still required.

Trial registration ClinicalTrials.gov NCT01034969

The Evolving Landscape for Complement Therapeutics in Rheumatic and Autoimmune Diseases

The complement system is increasingly understood to play major roles in the pathogenesis of human inflammatory and autoimmune diseases. Because of this situation, there are rapidly expanding commercial efforts to develop novel complement inhibitors and effector pathway-modulating drugs. This review provides insights into the evolving understanding of the complement system components, mechanisms of activation within and across the 3 pathways (classical, alternative, and lectin), how the pathways are normally controlled and then dysregulated in target tissues, and what diseases are known to be, in large part, complement-dependent through the successful development and approval of complement therapeutics in patients. Mechanisms of complement activation in rheumatoid arthritis, lupus, and thrombotic microangiopathies are also illustrated. In addition, the specific therapeutic drugs that are both approved and under development are discussed in the context of both nonrheumatic and rheumatic diseases. Finally, the methods by which the complement system can be assessed in humans through biomarker studies are outlined, with the goal of understanding, in specific patients, how the system is functioning.

Acquired C1 Inhibitor Deficiency

Acquired angioedema due to C1-INH deficiency (C1-INH-AAE) can occur when there are acquired (not inherited) deficiencies of C1-INH. A quantitative or functional C1-INH deficiency with negative family history and low C1q is diagnostic of C1-INH-AAE. The most common conditions associated with C1-INH-AAE are autoimmunity and B-cell lymphoproliferative disorders. A diagnosis of C1-INH-AAE can precede a diagnosis of lymphoproliferative disease and confers an increased risk for developing non-Hodgkin lymphoma. Treatment focuses on symptom control with therapies that regulate bradykinin activity (C1-INH concentrate, icatibant, ecallantide, tranexamic acid, androgens) and treatment of any underlying conditions.

Hereditary angioedema presenting as irritable bowel syndrome: a case of early closure

Abdominal pain is one of the most common reasons for outpatient and emergency department visits. We present one such case of early closure in a 32-year-old male with recurrent abdominal pain who was diagnosed with irritable bowel syndrome (IBS). Family history was suspicious for hereditary angioedema (HAE). The HAE workup came back positive, and the patient was started on prophylactic therapy, which led to an improvement in symptoms and quality of life. The purpose of this case is to create awareness among physicians to test for HAE in patients diagnosed with IBS who, based on their history or physical examination, have clinical suspicion for HAE.

C1q protein binds to the apoptotic nucleolus and causes C1 protease degradation of nucleolar proteins

In infection, complement C1q recognizes pathogen-congregated antibodies and elicits complement activation. Among endogenous ligands, C1q binds to DNA and apoptotic cells, but whether C1q binds to nuclear DNA in apoptotic cells remains to be investigated. With UV irradiation-induced apoptosis, C1q initially bound to peripheral cellular regions in early apoptotic cells. By 6 h, binding concentrated in the nuclei to the nucleolus but not the chromatins. When nucleoli were isolated from non-apoptotic cells, C1q also bound to these structures. In vivo, C1q exists as the C1 complex (C1qC1r2C1s2), and C1q binding to ligands activates the C1r/C1s proteases. Incubation of nucleoli with C1 caused degradation of the nucleolar proteins nucleolin and nucleophosmin 1. This was inhibited by the C1 inhibitor. The nucleoli are abundant with autoantigens. C1q binding and C1r/C1s degradation of nucleolar antigens during cell apoptosis potentially reduces autoimmunity. These findings help us to understand why genetic C1q and C1r/C1s deficiencies cause systemic lupus erythematosus.

Management of acute attacks of hereditary angioedema: role of ecallantide

Hereditary angioedema (HAE) is characterized as an episodic swelling disorder with autosomal dominant inheritance. Clinical features include nonpitting edema of external or mucosal body surfaces, and patients often present with swelling of the extremities, abdominal pain, and swelling of the mouth and throat, which can lead to asphyxiation. Patients with HAE classically have no associated urticaria, which is often referred to as nonhistaminergic angioedema. Treatment for HAE involves long-term prophylaxis, short-term prophylaxis, and management of acute attacks. Up until the past few years, acute HAE episodes were predominately treated with supportive measures. Three classes of medications have recently been approved by the US Food and Drug Administration (FDA) for the management of acute HAE attacks. Ecallantide, a recombinant protein that acts as a reversible inhibitor of kallikrein, is currently indicated for acute attacks of HAE in those aged ≥12 years. In two randomized, double-blind, placebo-controlled, multicenter trials, EDEMA3 and EDEMA4, patients treated with 30 mg of ecallantide demonstrated statistically significant improvement in symptoms compared to those on placebo. In addition to its use as treatment for HAE, ecallantide has been used off label in the management of nonhistaminergic angioedema, not due to HAE. Ecallantide has shown promise in the treatment of these other forms; however, data are limited to mainly case reports at this time. Ecallantide is generally a safe and well-tolerated medication; however, based on reports of anaphylaxis, ecallantide does contain a black box warning. Due to the risk of anaphylaxis, ecallantide cannot be self-administered and must be given by a health care professional. Overall, ecallantide is a safe and effective medication for the treatment of acute attacks of HAE.

Hereditary angioedema: what the gastroenterologist needs to know

Up to 93% of patients with hereditary angioedema (HAE) experience recurrent abdominal pain. Many of these patients, who often present to emergency departments, primary care physicians, general surgeons, or gastroenterologists, are misdiagnosed for years and undergo unnecessary testing and surgical procedures. Making the diagnosis of HAE can be challenging because symptoms and attack locations are often inconsistent from one episode to the next. Abdominal attacks are common and can occur without other attack locations. An early, accurate diagnosis is central to managing HAE. Unexplained abdominal pain, particularly when accompanied by swelling of the face and extremities, suggests the diagnosis of HAE. A family history and radiologic imaging demonstrating edematous bowel also support an HAE diagnosis. Once HAE is suspected, C4 and C1 esterase inhibitor (C1-INH) laboratory studies are usually diagnostic. Patients with HAE may benefit from recently approved specific treatments, including plasma-derived C1-INH or recombinant C1-INH, a bradykinin B2-receptor antagonist, or a kallikrein inhibitor as first-line therapy and solvent/detergent-treated or fresh frozen plasma as second-line therapy for acute episodes. Short-term or long-term prophylaxis with nanofiltered C1-INH or attenuated androgens will prevent or reduce the frequency and severity of episodes. Gastroenterologists can play a critical role in identifying and treating patients with HAE, and should have a high index of suspicion when encountering patients with recurrent, unexplained bouts of abdominal pain. Given the high rate of abdominal attacks in HAE, it is important for gastroenterologists to appropriately diagnose and promptly recognize and treat HAE, or refer patients with HAE to an allergist.

Drug-induced angioedema: experience of Italian emergency departments

Acute angioedema represents a cause of admission to the emergency department requiring rapid diagnosis and appropriate management to prevent airway obstruction. Several drugs, including angiotensin-converting enzyme inhibitors (ACE-I), nonsteroidal anti-inflammatory drugs (NSAIDs) and oral antidiabetics, have been reported to induce angioedema. The aim of this prospective observational study conducted in a setting of routine emergency care was to evaluate the incidence and extent of drug-induced non-histaminergic angioedema in this specific clinical setting, and to identify the class of drugs possibly associated with angioedema. Patients admitted to seven different emergency departments (EDs) in Rome with the diagnosis of angioedema and urticaria were enrolled during a 6-month period. Of the 120,000 patients admitted at the EDs, 447 (0.37 %) were coded as having angioedema and 655 (0.5 %) as having urticaria. After accurate clinical review, 62 cases were defined as drug-induced, non-histaminergic angioedema. NSAIDs were the most frequent drugs (taken by 22 out of 62 patients) associated with the angioedema attack. Of the remaining patients, 15 received antibiotic treatment and 10 antihypertensive treatment. In addition, we observed in our series some cases of angioedema associated with drugs (such as antiasthmatics, antidiarrheal and antiepileptics) of which there are few descriptions in the literature. The present data, which add much needed information to the existing limited literature on drug-induced angioedema in the clinical emergency department setting, will provide more appropriate diagnosis and management of this potentially life-threatening adverse event.

C1-esterase inhibitor deficiency in pediatric heart transplant recipients: incidence and findings on ultrasound

BACKGROUND

Acquired angioedema of the bowel caused by a deficiency of C1-esterase inhibitor can lead to severe abdominal pain with sudden onset, mimicking an acute surgical abdomen. In contrast to hereditary angioedema, which usually manifests in childhood, acquired angioedema is broadly recognized to affect people older than 40 years.

OBJECTIVE

To determine the incidence of acquired angioedema in a cohort of pediatric heart transplant recipients and assess imaging findings on ultrasonography.

MATERIALS AND METHODS

A cohort of 207 children and adolescents who had undergone heart transplantation were assessed at regular follow-up examinations for incidence of acquired angioedema. All patients received ACE inhibitors and immune inhibitors. Control examinations carried out in 3-month intervals included history, assessment of clinical symptoms, physical examination, US of the abdomen and laboratory blood analysis. In addition, if clinical symptoms were newly encountered, children were admitted between regularly scheduled intervals. We analyzed results of abdominal US for pathological findings of the bowel, and we assessed imaging findings in children diagnosed with acquired angioedema.

RESULTS

Acquired angioedema was diagnosed in 3/207 patients (2 girls ages 16 and 17 years and 1 boy age 9 months). These children presented with sudden onset of severe abdominal pain. The bowel wall was thickened in the presence of ascites. After a mean of 72 h, abdominal pains resolved. Thickening of bowel loops dissolved and ascites disappeared.

CONCLUSION

Single episodes of acquired angioedema were encountered in 1.4% of our series of pediatric heart transplant recipients. Radiologists should be familiar with this disease so they can diagnose it on US imaging.

Angiotensin converting enzyme inhibitor-induced gastrointestinal angioedema: a case series and literature review

GOALS

The objective of this study was to better understand the presenting signs and symptoms of angiotensin converting enzyme (ACE) inhibitor-induced gastrointestinal angioedema, review the medical literature related to this condition, and bring this diagnosis to the attention of clinicians.

BACKGROUND

Angioedema occurs in 0.1% to 0.7% of patients treated with ACE inhibitors and ACE inhibitors account for 20% to 30% of all angioedema cases presenting to emergency departments. However, only recently have ACE inhibitors been recognized as a cause of angioedema of the gastrointestinal tract. Patients with this disease present with one or more episodes of abdominal pain associated with nausea, vomiting, and/or diarrhea.

STUDY

We present four cases of ACE inhibitor-induced gastrointestinal angioedema seen at a single institution and review the literature of other case reports.

RESULTS

Review of the medical literature identified 27 case reports of ACE inhibitor-induced angioedema of the gastrointestinal tract. Multiple ACE inhibitors were implicated in these case reports suggesting that this disease is a class effect of ACE inhibitors. In cases where the race of the patient was stated, 50% were identified as being African American. Ascities was described as a radiographic finding in 16 of 27 cases. There were no reported cases of paracentesis or ascitic fluid analysis described in any of the identified case reports.

CONCLUSIONS

This series highlights ascites as a key feature that distinguishes ACE inhibitor-induced gastrointestinal angioedema from infectious enteritis. This series also confirms the increased incidence of this condition among African American women, an unpredictable interval between medication initiation and the development of symptoms, and the heightened probability of symptom recurrence if ACE inhibitors are not discontinued. ACE inhibitor-induced gastrointestinal angioedema is a rare cause of acute abdominal complaints, but is likely underdiagnosed and should be considered in the differential diagnosis of all individuals taking ACE inhibitors with such symptoms. Early recognition of ACE inhibitor-induced gastrointestinal angioedema may avoid recurrent episodes or costly, invasive evaluations.

Diagnosing angioedema

Angioedema usually occurs within the setting of allergic diseases or urticaria, but situations occur in which angioedema itself represents a disease, such as in hereditary angioedema. Evaluation of patients for recurrent angioedema without wheals must take into account both specific clinical signs and symptoms and specialized laboratory testing.

Risk of angioedema following invasive or surgical procedures in HAE type I and II--the natural history

Background

Hereditary angioedema (HAE), caused by deficiency in C1-inhibitor (C1-INH), leads to unpredictable edema of subcutaneous tissues with potentially fatal complications. As surgery can be a trigger for edema episodes, current guidelines recommend preoperative prophylaxis with C1-INH or attenuated androgens in patients with HAE undergoing surgery. However, the risk of an HAE attack in patients without prophylaxis has not been quantified.

Objectives

This analysis examined rates of perioperative edema in patients with HAE not receiving prophylaxis.

Methods

This was a retrospective analysis of records of randomly selected patients with HAE type I or II treated at the Frankfurt Comprehensive Care Centre. These were examined for information about surgical procedures and the presence of perioperative angioedema.

Results

A total of 331 patients were included; 247 underwent 700 invasive procedures. Of these procedures, 335 were conducted in 144 patients who had not received prophylaxis at the time of surgery. Categories representing significant numbers of procedures were abdominal (n = 113), ENT (n = 71), and gynecological (n = 58) procedures. The rate of documented angioedema without prophylaxis across all procedures was 5.7%; in 24.8% of procedures, the presence of perioperative angioedema could not be excluded, leading to a maximum potential risk of 30.5%. Predictors of perioperative angioedema could not be identified.

Conclusion

The risk of perioperative angioedema in patients with HAE type I or II without prophylaxis undergoing surgical procedures ranged from 5.7% to 30.5% (CI 3.5–35.7%). The unpredictability of HAE episodes supports current international treatment recommendations to consider short-term prophylaxis for all HAE patients undergoing surgery.

Current status of implementation of self-administration training in various regions of Europe, Canada and the USA in the management of hereditary angioedema

Results from a 16-question survey about self-administration of hereditary angioedema (HAE) therapy, administered in Europe, Canada and the USA, were used to guide discussion at an international HAE expert meeting. The aim was to capture information about current practice in self-administered HAE therapy in these countries, including self-administration training, the key benefits of switching to self-administration, the barriers to self-administration and trends in self-administration. Overall, switching to self-administration therapy is looked upon favourably from both patient and clinician perspectives by virtue of the potential improvement in quality of life arising from optimisation of therapy and early intervention. The recent changes to product licences allowing self-administration provide additional options for the management of HAE.