Lilian Varga

Management of hereditary angioedema in pediatric patients

Hereditary angioneurotic edema is a rare disorder caused by the congenital deficiency of C1 inhibitor. Recurring angioedematous paroxysms that most commonly involve the subcutis (eg, extremities, face, trunk, and genitals) or the submucosa (eg, intestines and larynx) are the hallmarks of hereditary angioneurotic edema. Edema formation is related to reduction or dysfunction of C1 inhibitor, and conventional therapy with antihistamines and corticosteroids is ineffective. Manifestations occur during the initial 2 decades of life, but even today there is a long delay between the onset of initial symptoms and the diagnosis of hereditary angioneurotic edema. Although a variety of reviews have been published during the last 3 decades on the general management of hereditary angioneurotic edema, little has been published regarding management of pediatric hereditary angioneurotic edema. Thus, we review our experience and published data to provide an approach to hereditary angioneurotic edema in childhood.

Recombinant human C1-inhibitor in the treatment of acute angioedema attacks.

BACKGROUND: Patients with hereditary C1‐inhibitor deficiency have recurrent attacks of angioedema, preferably treated with C1‐inhibitor concentrate. A recombinant human C1‐inhibitor (rHuC1INH) was developed, derived from milk from transgenic rabbits. This study was undertaken to investigate the effects of rHuC1INH in the treatment of acute angioedema attacks in patients with a hereditary C1‐inhibitor deficiency.

Diversity in Intrinsic Strengths of the Human Complement System: Serum C4 Protein Concentrations Correlate with C4 Gene Size and Polygenic Variations, Hemolytic Activities, and Body Mass Index

Among the genes and proteins of the human immune system, complement component C4 is extraordinary in its frequent germline variation in the size and number of genes. Definitive genotypic and phenotypic analyses were performed on a central European population to determine the C4 polygenic and gene size variations and their relationships with serum C4A and C4B protein concentrations and hemolytic activities. In a study population of 128 healthy subjects, the number of C4 genes present in a diploid genome varied between two to five, and 77.4% of the C4 genes belonged to the long form that contains the endogenous retrovirus HERV-K(C4). Intriguingly, higher C4 serum protein levels and higher C4 hemolytic activities were often detected in subjects with short C4 genes than those with long genes only, suggesting a negative epistatic effect of HERV-K(C4) on the expression of C4 proteins. Also, the body mass index appeared to affect the C4 serum levels, particularly in the individuals with medium or high C4 gene dosages, a phenomenon that was dissimilar in several aspects from the established correlation between body mass index and serum C3. As expected, there were strong, positive correlations between total C4 gene dosage and serum C4 protein concentrations, and between serum C4 protein concentrations and C4 hemolytic activities. There were also good correlations between the number of long genes with serum levels of C4A, and the number of short genes with serum levels of C4B. Thus, the polygenic and gene size variations of C4A and C4B contribute to the quantitative traits of C4 with a wide range of serum protein levels and hemolytic activities, and consequently the power of the innate defense system.

Studies on the interactions between C-reactive protein and complement proteins

Several studies have investigated the interactions between C‐reactive protein (CRP) and various complement proteins but none of them took into consideration the different structural forms of CRP. The aim of our study was to investigate whether the different antigenic forms of CRP are able to bind C1q, to trigger activation of the C1 complex and to study the ability of the various CRP forms to bind complement factor H (FH) and C4b‐binding protein (C4BP). Interactions between various CRP forms and complement proteins were analysed in enzyme‐linked immunosorbent assay and surface plasmon resonance tests and activation of the C1 complex was followed in a reconstituted system using purified C1q, C1r and C1s in the presence of C1‐INH. Native, ligand‐unbound CRP activated the classical pathway weakly. After binding to phosphocholine, native CRP bound C1q and significantly activated C1. Native CRP complexed to phosphocholine did not bind the complement regulatory proteins FH and C4BP. After disruption of the pentameric structure of CRP, as achieved by urea‐treatment or by site‐directed mutagenesis, C1q binding and C1 activation further increased and the ability of CRP to bind complement regulatory proteins was revealed. C1q binds to CRP through its globular head domain. The binding sites on CRP for FH and C4BP seemed to be different from that of C1q. In conclusion, in parallel with the increase in the C1‐activating ability of different CRP structural variants, the affinity for complement regulatory proteins also increased, providing the biological basis for limitation of excess complement activation.

The efficacy of short-term danazol prophylaxis in hereditary angioedema patients undergoing maxillofacial and dental procedures

PURPOSE This study evaluated the efficacy of short-term danazol prophylaxis in hereditary angioedema patients undergoing maxillofacial or dental procedures. PATIENTS AND METHODS Twelve patients with a history of edema after dental procedures were administered danazol (600 mg/d) 4 days preoperatively and 4 days postoperatively. The serum levels of complement components were determined preoperatively and postoperatively as well as at 6, 12 and 24 hours in six patients. RESULTS None of the 12 patients developed angioneurotic edema. The serum levels of the complement components were decreased immediately after surgery and returned to normal within 24 hours. CONCLUSION The short-term prophylactic use of danazol in patients with hereditary angioedema undergoing oral surgery is an effective preventive measure.

Eradication of Helicobacter pylori and improvement of hereditary angioneurotic oedema

Helicobacter pylori infection is thought to be a causal factor in various dermatological disorders. We assessed the frequency of H pylori infection in 65 patients with hereditary angioneurotic oedema. We measured the serum concentration of antibodies against H pylori and did the carbon-14-urease breath test in patients with positive H pylori serology. 19 of 65 patients had H pylori infection. All patients with infection, and 11 of 46 without infection, had a history of recurrent episodes of acute abdominal pain. We successfully eradicated H. pylori infection in 18 patients. The frequency of abdominal symptoms was significantly higher in the infected group (p=0.002 after adjustment for age). In nine of 19 patients with dyspepsia, the frequency of oedematous episodes decreased from 100 over 10 months before eradication to 19 during the 10-month follow-up period. Screening for, and eradication of, H pylori infection seems to be justified in patients with hereditary angioneurotic oedema.

Strong complement activation after acute ischemic stroke is associated with unfavorable outcomes

OBJECTIVE According to data from animal models, complement activation plays a major role in the brain injury after acute ischemic stroke. Scarce findings are, however, available on the detection of complement activation products in stroke patients. METHODS We have measured plasma levels of the five complement activation products (C1rC1sC1inh, C4d, C3a, C5a and SC5b-9) in samples of 26 patients with ischemic stroke upon admission. Twenty-six patients with severe carotid atherosclerosis served as patient controls. RESULTS Levels of two activation products (SC5b-9 and C4d)) were significantly elevated in the plasma of stroke patients, SC5b-9 levels, exhibited significant positive correlation with the clinical severity of stroke, the severity of neurological deficit, as well as with the level of functional disability. CONCLUSION These findings suggest that complement activation plays an active role in the development of brain infarct. The measurement of complement activation products might help to determine the clinical prognosis after acute ischemic stroke. Furthermore, there is potential usefulness of complement modulating therapy in ischemic stroke.

Functional C1-inhibitor diagnostics in hereditary angioedema: assay evaluation and recommendations.

Hereditary angioedema (HAE) is an autosomal dominant disease characterized by recurrent episodes of potentially life-threatening angioedema. The most widespread underlying genetic deficiency is a heterozygous deficiency of the serine protease inhibitor C1 esterase inhibitor (C1-Inh). In addition to low C4 levels, the most important laboratory parameter for correct diagnosis of HAE or angioedema due to acquired C1-Inh deficiency is reduced C1-Inh function (fC1-Inh). No direct recommendations about the assays for fC1-Inh or sample handling conditions are available, although this would prove especially useful when a laboratory first starts to offer assays on fC1-Inh for HAE diagnosis. In the present study we evaluated the performance of fC1-Inh assays in the 15 different laboratories that are specialised in HAE diagnostics and assessed inter-laboratory variation with each laboratory using their own assays and standards. A double-blind survey was conducted using plasma/serum samples from healthy donors and HAE patients and the uniformity of HAE diagnosis was evaluated. It can be concluded that the diagnosis of fC1-Inh deficiency was made correctly in most cases in this survey. We can recommend the chromogenic assay for the determination of fC1-Inh, while the complex ELISA needs further investigation.

Erythema marginatum preceding an acute oedematous attack of hereditary angioneurotic oedema.

Henriette Farkas1, George Harmat2, Andrea Fay3, Bela Fekete4, Istvan Karadi4, Beata Visy1 and Lilian Varga5 1Allergology & Angioedema Outpatient Clinic and 3Dermatology Outpatient Clinic, Semmelweis University, Kutvolgyi Clinical Centre, Kutvolgyi ut 4., H-1125 Budapest, Hungary. 2First Department of Paediatrics, Madarasz Children’s Hospital, Budapest, Hungary. 4Third Department of Internal Medicine, Semmelweis University, Budapest, Hungary. 5Complement Laboratory, National Institute of Haematology and Immunology, Budapest, Hungary. E-mail: farkash@kut.sote.hu

Ultrasonography in the diagnosis and monitoring of ascites in acute abdominal attacks of hereditary angioneurotic oedema.

Background Hereditary angioneurotic oedema (HAE) is a rare cause of ascites. As acute abdominal attacks of the disease can mimic surgical emergencies, prompt and accurate diagnosis is essential. This study was undertaken to evaluate the usefulness of serial abdominal ultrasound (US) examinations. Patients and methods Seventy patients with HAE were followed up for almost a decade. All patients presenting with an acute oedematous attack underwent abdominal US, which was then repeated 24 and 48 h after appropriate therapy. Results Twenty-two acute oedematous attacks with abdominal complaints severe enough to justify hospital admission occurred in the study population. Abdominal US performed during the attack showed oedematous thickening of the intestinal wall in 80% of cases and invariably demonstrated the presence of free peritoneal fluid in all patients. Rapid symptomatic relief achieved by treatment was accompanied by the significant regression of US abnormalities. Conclusions Transitory ascites demonstrated by abdominal US is a clue to the diagnosis of an acute abdominal attack of HAE. The possibility of HAE should always be considered whenever unexplained abdominal pain recurs with or without ascites.