The international WAO/EAACI guideline for the management of hereditary angioedema-The 2017 revision and update.

Hereditary Angioedema (HAE) is a rare and disabling disease. Early diagnosis and appropriate therapy are essential. This update and revision of the global guideline for HAE provides up-to-date consensus recommendations for the management of HAE. In the development of this update and revision of the guideline, an international expert panel reviewed the existing evidence and developed 20 recommendations that were discussed, finalized and consented during the guideline consensus conference in June 2016 in Vienna. The final version of this update and revision of the guideline incorporates the contributions of a board of expert reviewers and the endorsing societies. The goal of this guideline update and revision is to provide clinicians and their patients with guidance that will assist them in making rational decisions in the management of HAE with deficient C1-inhibitor (type 1) and HAE with dysfunctional C1-inhibitor (type 2). The key clinical questions covered by these recommendations are: (1) How should HAE-1/2 be defined and classified?, (2) How should HAE-1/2 be diagnosed?, (3) Should HAE-1/2 patients receive prophylactic and/or on-demand treatment and what treatment options should be used?, (4) Should HAE-1/2 management be different for special HAE-1/2 patient groups such as pregnant/lactating women or children?, and (5) Should HAE-1/2 management incorporate self-administration of therapies and patient support measures?

Phase II study results of a replacement therapy for hereditary angioedema with subcutaneous C1-inhibitor concentrate.

BACKGROUND: Hereditary angioedema (HAE) due to C1 inhibitor deficiency manifests as recurrent swelling attacks that can be disabling and sometimes fatal. Long-term prophylaxis with twice-weekly intravenous injections of plasma-derived C1-inhibitor (pdC1-INH) has been established as an effective treatment. Subcutaneous (SC) administration of pdC1-INH has not been studied in patients with HAE. METHODS: This open-label, dose-ranging, crossover study (COMPACT Phase II) was conducted in 18 patients with type I or II HAE who received two of twice-weekly 1500, 3000, or 6000 IU SC doses of highly concentrated volume-reduced CSL830 for 4 weeks each. The mean trough plasma levels of C1-INH functional activity, C1-INH and C4 antigen levels during Week 4, and overall safety and tolerability were evaluated. The primary outcome was model-derived steady-state trough C1-INH functional activity. RESULTS: After SC CSL830 administration, a dose-dependent increase in trough functional C1-INH activity was observed. C1-INH and C4 levels both increased. The two highest dose groups (3000 and 6000 IU) achieved constant C1-INH activity levels above 40% values, a threshold that was assumed to provide clinical protection against angioedema attacks. Compared with intravenous injection, pdC1-INH SC injection with CSL830 showed a lower peak-to-trough ratio and more consistent exposures. All doses were well tolerated. Mild-to-moderate local site reactions were noted with pain and swelling being the most common adverse event. CONCLUSIONS: Subcutaneous volume-reduced CSL830 was well tolerated and led to a dose-dependent increase in physiologically relevant functional C1-INH plasma levels. A clinical outcome study of SC CSL830 in patients with HAE warrants further investigation.

Classification, diagnosis, and approach to treatment for angioedema: consensus report from the Hereditary Angioedema International Working Group.

Angioedema is defined as localized and self-limiting edema of the subcutaneous and submucosal tissue, due to a temporary increase in vascular permeability caused by the release of vasoactive mediator(s). When angioedema recurs without significant wheals, the patient should be diagnosed to have angioedema as a distinct disease. In the absence of accepted classification, different types of angioedema are not uniquely identified. For this reason, the European Academy of Allergy and Clinical Immunology gave its patronage to a consensus conference aimed at classifying angioedema. Four types of acquired and three types of hereditary angioedema were identified as separate forms from the analysis of the literature and were presented in detail at the meeting. Here, we summarize the analysis of the data and the resulting classification of angioedema.

Evidence-based recommendations for the therapeutic management of angioedema owing to hereditary C1 inhibitor deficiency: consensus report of an International Working Group.

Angioedema owing to hereditary deficiency of C1 inhibitor (HAE) is a rare, life-threatening, disabling disease. In the last 2 years, the results of well-designed and controlled trials with existing and new therapies for this condition have been published, and new treatments reached the market. Current guidelines for the treatment for HAE were released before the new trials and before the new treatments became available and were essentially based on observational studies and expert opinion. To provide evidence-based HAE treatment guidelines supported by the new studies, a conference was held in Gargnano del Garda, Italy, from September 26 to 29, 2010. The meeting hosted 58 experienced HAE expert physicians, representatives of pharmaceutical companies and representatives of HAE patients' associations. Here, we report the topics discussed during the meeting and evidence-based consensus about management approaches for HAE in adult/adolescent patients.

Corticosteroid-induced gene expression in allergen-challenged asthmatic subjects taking inhaled budesonide.

BACKGROUND AND PURPOSE: Inhaled corticosteroids (ICS) are the cornerstone of asthma pharmacotherapy and, acting via the glucocorticoid receptor (GR), reduce inflammatory gene expression. While this is often attributed to a direct inhibitory effect of the GR on inflammatory gene transcription, corticosteroids also induce the expression of anti-inflammatory genes in vitro. As there are no data to support this effect in asthmatic subjects taking ICS, we have assessed whether ICS induce anti-inflammatory gene expression in subjects with atopic asthma. EXPERIMENTAL APPROACH: Bronchial biopsies from allergen-challenged atopic asthmatic subjects taking inhaled budesonide or placebo were subjected to gene expression analysis using real-time reverse transcriptase-PCR for the corticosteroid-inducible genes (official gene symbols with aliases in parentheses): TSC22D3 [glucocorticoid-induced leucine zipper (GILZ)], dual-specificity phosphatase-1 (MAPK phosphatase-1), both anti-inflammatory effectors, and FKBP5 [FK506-binding protein 51 (FKBP51)], a regulator of GR function. Cultured pulmonary epithelial and smooth muscle cells were also treated with corticosteroids before gene expression analysis. KEY RESULTS: Compared with placebo, GILZ and FKBP51 mRNA expression was significantly elevated in budesonide-treated subjects. Budesonide also increased GILZ expression in human epithelial and smooth muscle cells in culture. Immunostaining of bronchial biopsies revealed GILZ expression in the airways epithelium and smooth muscle of asthmatic subjects. CONCLUSIONS AND IMPLICATIONS: Expression of the corticosteroid-induced genes, GILZ and FKBP51, is up-regulated in the airways of allergen-challenged asthmatic subjects taking inhaled budesonide. Consequently, the biological effects of corticosteroid-induced genes should be considered when assessing the actions of ICS. Treatment modalities that increase or decrease GR-dependent transcription may correspondingly affect corticosteroid efficacy.

Abstracts from the North American Rhinology & Allergy Conference, February 3, 2011, Puerto Rico.

INTRODUCTION: To establish the efficacy of bepotastine besilate ophthalmic solution (bepotastine) 1.5%, a dual acting histamine H1 receptor antagonist approved for treatment of ocular itching associated with allergic conjunctivitis, compared to placebo in relieving ocular itching and redness for subjects with active allergic rhinoconjunctivitis. METHODS: A randomized, double-masked, placebo-controlled, confirmatory natural exposure study of bepotastine 1.5% and placebo was conducted during allergy season at 12 clinical sites throughout the U.S. Following a 7-day screening period, eligible subjects ≥12 years old were assigned in a 1:1 ratio to dosing OU b.i.d. either bepotastine 1.5% (n = 123) or placebo (n = 122). Subjects recorded instantaneous grades for their ocular symptoms prior to their next dose for 14 consecutive days. Clinically significant reduction in ocular sign or symptom grades between treatment groups required p ≤ 0.05 as determined by ANCOVA analysis. RESULTS: Significant clinical effectiveness with bepotastine 1.5% was demonstrated over the 2-week treatment period in comparison to placebo in the intent-to-treat population for reducing mean instantaneous grades for both ocular itching (p = 0.007) and redness (p = 0.001). Investigator rating of efficacy over the 2-week treatment period across response categories was also superior for bepotastine 1.5% compared to placebo (p = 0.024). Only one subject discontinued participation in the study due to an adverse event. CONCLUSIONS: These data support bepotastine 1.5% as an effective treatment for allergen-induced signs and symptoms in a clinical study designed to closely resemble the conditions under which patients with allergic rhinoconjunctivitis would require treatment.

Double-stranded RNA increases kinin B1 receptor expression and function in human airway epithelial cells.

Increased levels of kinins have been detected within the airways during upper respiratory viral infections (URIs). Rhinovirus, the major URI associated with acute exacerbations of asthma, is an ssRNA virus that primarily infects the airway epithelium and produces dsRNA during replication. We asked whether dsRNA could increase the expression of kinin receptors in airway epithelial cells, thereby potentiating the inflammatory consequences of kinin generation. Human airway epithelial cell line BEAS-2B was stimulated with the dsRNA analog Poly I:C and kinin receptor expression detected by quantitative RT-PCR as well as radioligand binding. Poly I:C induced an increase in B1 and B2 receptor mRNA levels in BEAS-2B and primary human normal bronchial epithelial cells. At the cell surface, only B1 receptor expression was increased by Poly I:C. Furthermore, pretreatment of BEAS-2B cells with Poly I:C enhanced the induction of phospho-ERK following B1 receptor ligand stimulation. To investigate whether these finding had potential in vivo relevance, we assessed B1 receptor expression in nasal tissue obtained from 8 normal human subjects with URIs and 3 control subjects. Five of the URI subjects demonstrated increased B1 receptor mRNA compared to the 3 control subjects. We suggest that increased expression of B1 receptor in the human airway following a URI could increase the risk of an exacerbation of asthma by contributing to increased inflammation in the airway.

Endothelin-1 (ET-1) decreases human bronchial epithelial cell migration and proliferation: implications for airway remodeling in asthma.

The respiratory epithelium is a protective barrier that also functions as an interactive metabolically active component of the lung. The healing and repair of the epithelium involves initial migration of epithelial cells, and subsequent proliferation. The purpose of our study was to assess the effect of inflammatory mediators, in particular endothelin-1 (ET-1), on bronchial epithelial cell proliferation and migration. Under the conditions studied, ET-1 slows proliferation of human bronchial epithelial cells, compared to control (p < 0.01). The presence of ET-1 results in slower migration of epithelial cells compared to control (p < 0.04). Based on these in vitro findings, ET-1 could potentially lead to inhibition of repair of the lung epithelium and enhanced remodeling.

Chemoattractant-stimulated NF-kappaB activation is dependent on the low molecular weight GTPase RhoA.

Chemoattractants bind to seven transmembrane-spanning, G-protein-coupled receptors on monocytes and neutrophils and induce a variety of functional responses, including activation of the transcription factor NF-kappaB. The signaling mechanisms utilized by chemoattractants to activate NF-kappaB in human peripheral blood monocytes are poorly defined. We previously demonstrated that fMet-Leu-Phe (fMLP) stimulates NF-kappaB activation, and this function of fMLP requires phosphatidylinositol 3-kinase (PI3K). Here we present evidence that fMLP activates RhoA and that fMLP-induced NF-kappaB activation requires this small GTPase. Stimulation of monocytes with fMLP rapidly activated RhoA as well as NF-kappaB, and their activation was markedly reduced by pertussis toxin treatment. Pretreatment of monocyte with a RhoA inhibitor, C3 transferase from Clostridium botulinum, effectively blocked fMLP-induced NF-kappaB activation as well as interleukin-1beta gene expression. A dominant negative form of RhoA (T19N) also inhibited fMLP-stimulated reporter gene expression in a kappaB-dependent manner. Cotransfection of the monocytic THP1 cells with a constitutively active form of RhoA (Q63L) with the promoter reporter plasmid results in a marked increase in NF-kappaB-mediated reporter gene expression. Furthermore, the PI3K inhibitors wortmannin and LY294002 block RhoA activation induced by fMLP. These results demonstrate that low molecular weight GTPase RhoA is a novel signal transducer for fMLP-induced NF-kappaB activation and Galpha(i) or Galpha(o) class of heterotrimeric G proteins likely mediate RhoA activation via PI3K in human peripheral blood monocytes.

Detection of C1 inhibitor mutations in patients with hereditary angioedema.

BACKGROUND: Hereditary angioedema (HAE) results from a deficiency in the functional level of C1 inhibitor caused by mutations in the C1 inhibitor gene. The mutations responsible for HAE have been shown to be heterogeneous. OBJECTIVE: Because the identification of C1 inhibitor mutations may depend, in part, on the technique used to screen for mutations, we screened the entire C1 inhibitor coding region to identify mutations in a cohort of patients with HAE. METHODS: By using single-stranded conformational polymorphism analysis, 24 subjects with HAE from 16 different kindreds were screened for C1 inhibitor polymorphisms. C1 inhibitor mutations were identified by sequencing the exons containing identified polymorphisms. RESULTS: All 24 subjects with HAE had identifiable polymorphisms, involving exons 2, 3, 4, 5, or 8. Fourteen different C1 inhibitor mutations were identified: 8 missense, 1 nonsense, 4 frameshift, and 1 small deletion mutations. No large deletions or duplications were found. Nine of the 14 mutations represent newly recognized C1 inhibitor mutations, 6 of which involve exon 4. CONCLUSIONS: Single-stranded conformational polymorphism is an effective approach for identifying new mutations in HAE. Elucidation of the range of C1 inhibitor mutations causing HAE is important for both defining which residues are required for C1 inhibitor secretion or function and providing the basis for future studies to define the relationship between the C1 inhibitor genotype and disease severity.

fMet-Leu-Phe stimulates proinflammatory cytokine gene expression in human peripheral blood monocytes: the role of phosphatidylinositol 3-kinase.

The fMLP-stimulated release of proinflammatory cytokines such as IL-1 by human peripheral blood monocytes is an important component of the inflammatory process. The signaling mechanisms used by fMLP to stimulate the release of cytokines are still incompletely understood. We previously demonstrated that fMLP-stimulated NF-kappaB activation in PBMC and now we present evidence that the lipid products of phosphatidylinositol 3-kinase (PI 3-kinase) are required for fMLP-stimulated activation of NF-kappaB. Pretreatment with the PI 3-kinase inhibitors, wortmannin and LY294002, effectively blocked fMLP-induced IL-1beta gene expression as well as NF-kappaB activation. Transient transfection of THP1 cells with a dominant-negative mutant of the PI 3-kinase p85 subunit also abrogated fMLP-induced kappaB activity. These results suggest a potential role of fMLP in the transcription of proinflammatory cytokines and provide the first evidence that such regulation may occur through PI 3-kinase activity.

Mechanisms and regulation of polymorphonuclear leukocyte and eosinophil adherence to human airway epithelial cells.

Polymorphonuclear leukocytes (PMN) and eosinophils (Eos) are important cellular participants in a variety of acute and chronic inflammatory reactions in the airway. Histologic evidence has implicated direct interactions between these two subsets of leukocytes and airway epithelial cells during inflammation. A comprehensive characterization and comparison of physiologic stimuli and adhesion molecule involvement in granulocyte-epithelial-cell interactions done with nontransformed human airway epithelial cells has not been reported. We therefore examined the regulation and biochemical mechanisms governing granulocyte-epithelial-cell adhesion, using either purified PMN or Eos and primary cultures of human bronchial epithelial cells (HBECs). We investigated the involvement of a number of proinflammatory signals associated with allergic and nonallergic airway inflammation, as well as the contribution of several epithelial and leukocyte adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and members of the beta(1), beta(2), and beta(7) integrin families. ICAM-1 was expressed at low levels on cultured HBECs and was markedly upregulated after stimulation with interferon (IFN)-gamma or, to a lesser extent, with tumor necrosis factor (TNF)-alpha or interleukin (IL)-1. VCAM-1 was not present on resting HBECs, and was not upregulated after stimulation with IFN-gamma, IL-1, IL-4, or TNF-alpha. PMN adhesion to HBECs could be induced either through activation of PMN with IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), or C5a, but not with IL-5 or by preactivation of HBECs with TNF-alpha or IFN-gamma. Blocking antibody studies indicated that PMN-HBEC adherence depended on beta(2) integrins, primarily alpha(M)beta(2) (Mac-1). Adherence of Eos to HBECs could be induced through activation of Eos with IL-5, GM-CSF, or C5a, but not with IL-8 or by prior activation of HBECs with TNF-alpha of IFN-gamma. Maximal adhesion of Eos and PMN required pretreatment of HBECs with either TNF-alpha or IFN-gamma in addition to leukocyte activation. Adherence of Eos to unstimulated HBECs was mediated through both beta(1) and beta(2) integrins, whereas adhesion of Eos to activated HBECs was dominated by beta(2) integrins. Adhesion of both Eos and PMN was inhibited by treatment of HBECs with blocking antibodies to ICAM-1. Differential utilization of beta(1) and beta(2) integrins by Eos, depending on the activation state of the epithelium, is a novel finding and may affect activation and/or recruitment of Eos in airway tissue. Mechanisms of adhesion of HBECs to Eos and PMN, as evidenced by the different responsiveness of the two latter types of cells to IL-8 and IL-5, may account for a prevalence of Eos over PMN in certain airway diseases.

Requirement of phosphatidylinositol 3-kinase activity for bradykinin stimulation of NF-kappaB activation in cultured human epithelial cells.

The signaling mechanisms utilized by bradykinin (BK) to activate the transcription factor nuclear factor kappaB (NF-kappaB) are poorly defined. We previously demonstrated that BK-stimulated NF-kappaB activation requires the small GTPase RhoA. We present evidence that BK-induced NF-kappaB activation both activates and requires phosphatidylinositol 3-kinase (PI 3-kinase) in A549 human epithelial cells. Pre-treatment with the PI 3-kinase-specific inhibitors, wortmannin, and LY294002 effectively blocked BK-induced PI 3-kinase activity. Wortmannin and LY294002 also abolished BK-induced NF-kappaB activation, as did transient transfection with a dominant negative mutant of the p85 subunit. BK-stimulated PI 3-kinase activity and NF-kappaB activation were sensitive to pertussis but not cholera toxin, suggesting that the B2 BK receptors transducing the response were coupled to Galphai or Galphao heterotrimeric G proteins. Tumor necrosis factor alpha (TNFalpha) also stimulated increased PI 3-kinase activity, however TNFalpha-stimulated NF-kappaB activation was not affected by the PI 3-kinase inhibitors or the p85 dominant negative mutant. These findings provide evidence that BK-induced NF-kappaB activation utilizes a signaling pathway that requires activity of both RhoA and PI 3-kinase and is distinct from the signaling pathway utilized by TNFalpha. Furthermore, we show that the p85 regulatory subunit is required for activation of PI 3-kinase activity by this G protein-coupled receptor.

Induction of human B2 bradykinin receptor mRNA and membrane receptors by IFNgamma.

A potential mechanism for the increased sensitivity of inflamed tissues to bradykinin is the upregulation of bradykinin receptor expression. We report that recombinant human IFNgamma stimulated a concentration-dependent increase in cell surface bradykinin receptor expression in intact T24 human epithelial-like cells, determined by radioligand binding analysis. Analysis of specific [3H]-bradykinin binding revealed that IFNgamma-treated cells had a two- to threefold increase in bradykinin receptor number compared to the controls with no effect on receptor affinity. The ability of IFNgamma to stimulate increased bradykinin receptor expression was abrogated by treatment with either the transcription inhibitor actinomycin D or the protein synthesis inhibitor cycloheximide. IFNgamma enhanced steady-state human B2 bradykinin receptor mRNA expression in the T24 cells in a dose-dependent manner. B2 bradykinin receptor mRNA expression was increased as early as 1 h following IFNgamma stimulation, and continued to accumulate for 24 h. Bradykinin-stimulated intracellular calcium mobilization was also increased in IFNgamma-treated T24 cells compared to controls. The ability of IFNgamma to upregulate B2 bradykinin receptors in primary epithelial cells was demonstrated using cultured human airway epithelial cells. These observations suggest that increasing IFNgamma levels during inflammation may upregulate the expression of B2 bradykinin receptors, leading to increased sensitivity to bradykinin.

Role of the Rho GTPase in bradykinin-stimulated nuclear factor-kappaB activation and IL-1beta gene expression in cultured human epithelial cells.

Recent evidence suggests a novel role of bradykinin (BK) in stimulating gene transcription. This study examined the effect of BK on nuclear factor kappaB (NF-kappaB) activation and IL-1beta synthesis in human epithelial cells. Stimulation of A549 cells and primary bronchial epithelial cells with BK rapidly activated NF-kappaB. BK also increased the level of secreted immunoreactive IL-1beta in A549 culture supernatants, an effect that was blocked by actinomycin D and the B2 BK receptor antagonist HOE-140. The role of NF-kappaB activation in BK-induced IL-1beta synthesis was demonstrated by the ability of BK to stimulate increased chloramphenicol acetyltransferase (CAT) activity in A549 cells transfected with a reporter plasmid containing three kappaB enhancers from the IL-1beta gene, while deletion of the kappaB enhancer sequences eliminated BK-stimulated CAT activity. C3 transferase exoenzyme, an inhibitor of Rho, abolished BK-induced NF-kappaB activation at 10 microg/ml and significantly inhibited BK-stimulated IL-1beta synthesis at 5 microg/ml. A dominant-negative form of RhoA (T19N) inhibited BK-stimulated reporter gene expression in a dose-dependent and kappaB-dependent manner. Cotransfection of A549 cells with an expression vector encoding a constitutively active form of RhoA (Q63L) along with the IL-1beta promoter-CAT reporter plasmid resulted in a marked increase in NF-kappaB activity compared with transfection with the IL-1beta promoter-CAT reporter plasmid alone. These results demonstrate that BK stimulates NF-kappaB activation and IL-1beta synthesis in A549 cells, and that RhoA is both necessary and sufficient to mediate this effect.

Evaluation of a school-based asthma education program for inner-city children.

BACKGROUND: We have previously reported a high prevalence of current asthma-related symptoms affecting predominantly Hispanic, socioeconomically disadvantaged schoolchildren in Southeast San Diego. OBJECTIVE: We sought to assess the impact of a school-based education program on asthma outcomes. METHODS: In cooperation with the San Diego Unified Schools, we developed and implemented a school-based asthma education program. Based on the National Heart, Lung, and Blood Institute consensus guidelines for asthma, the five-session bilingual, interactive curriculum was conducted in 20-minute segments. Asthma knowledge was tested before and after the education program, and asthma severity was prospectively assessed at monthly intervals. Outcome parameters were compared in educated and control (noneducated) fourth grade students with asthma by using nonparametric techniques. RESULTS: After asthma education, students demonstrated improvement with increases in mean scores for: asthma knowledge quiz from 9.9 (SEM = 0.44, n = 34) to 13.7 (SEM = 0.30); peak flowmeter technique from 3.9 (SEM = 0.33, n = 32) to 6.4 (SEM = 0.29); and inhaler technique from 2.3 (SEM = 0.26, n = 32) to 4.3 (SEM = 0.26). All changes were highly significant (p < or = 0.00001 as determined by Wilcoxon matched-pairs signed-rank test). Mean score comparisons for asthmatic control students given paired examinations after a time interval matched with the educated students, did not reach statistical significance: quiz score of 11.3 (SEM = 0.80, n = 11) versus 10.9 (SEM = 0.68), peak flowmeter technique score of 2.6 (SEM = 0.50, n = 18) versus 3.1 (SEM = 0.37) , and inhaler technique score of 2.5 (SEM = 0.37, n = 18) versus 2.2 (SEM = 0.31). Prospective monthly data were collected on 27 educated and 15 control asthmatic subjects. Severity of asthma was not significantly different between groups at entry to the study. Symptom questionnaires, validated for functional asthma severity, revealed a significant reduction in mean symptom scores at 180 days for the educated (2.87, SEM = 0.447) versus the control (4.36, SEM = 0.573) groups (p = 0.0188 as determined by the Mann-Whitney U test). CONCLUSION: Child-centered asthma education can be successfully conducted in the school setting, resulting in increased asthma knowledge, improved skills for peak flowmeter and inhaler use, and a reduction in the severity of asthma symptoms.

Urticaria, angioedema, and autoimmunity.

Until relatively recently, the pathophysiologic significance of the recognized associations between autoimmunity and swelling was largely unknown. It has now become clear that autoimmunity can play a critical role in the pathogenesis of chronic urticaria and acquired C1-INH deficiency with angioedema. Chronic urticaria has been associated with antithyroid autoantibodies, anti-IgE autoantibodies, and anti-Fc epsilon RI autoantibodies. The latter two autoantibodies are particularly interesting in that they have been shown to be capable of directly causing mast cell degranulation. It appears likely, therefore, that most cases of chronic urticaria will ultimately be considered an autoimmune disease rather than an allergic disease. The link between autoimmunity and the development of acquired C1-INH deficiency is also of interest. Recent studies suggest that the majority of acquired C1-INH deficiency patients have anti-C1-INH autoantibodies that appear to be responsible for the development of the C1-INH deficiency. In addition, both chronic urticaria and C1-INH deficiency can be associated with other autoimmune diseases, although the importance of these associations remains to be determined. Recognition of the role of autoantibodies in the pathogenesis of chronic urticaria and acquired C1-INH deficiency has altered the range of diagnostic and therapeutic approaches that need to be considered in approaching patients with chronic urticaria or acquired C1-INH deficiency. Future progress in understanding the genesis of these diseases may help elucidate the mechanism of autoantibody generation.

Analysis of an exon 1 polymorphism of the B2 bradykinin receptor gene and its transcript in normal subjects and patients with C1 inhibitor deficiency.

The B2 bradykinin receptor (B2BKR) mediates most of the inflammatory actions of bradykinin. To evaluate its potential role in allergic diseases, we assessed the structure of the human B2BKR gene. Screening a human placenta genomic DNA library identified only clones containing exons 2 and 3. Human placenta and colon tissues were used for 5' rapid amplification of complementary DNA ends to identify nine exon 1 clones, each containing one 9 bp and two 1 bp deletions compared with published sequences. Exon 1 genomic polymerase chain reaction of human leukocyte DNA revealed two distinct products, which were shown to differ by the presence or absence of the 9 bp deletion. Alleles with the 9 bp deletion were designated as (-)21-29, whereas alleles without the deletion were designated as (+)21-29. Genomic polymerase chain reaction in 39 Caucasian, 31 African-American, and 32 Asian normal subjects revealed a highly significant difference in the allelic frequency of the two genotypes, primarily because of an absence of the (+)21-29 allele in Asian subjects. Analysis of steady-state B2BKR messenger RNA levels by reverse-transcription polymerase chain reaction in heterozygous normal subjects revealed consistently higher expression of (-)21-29 transcripts. To investigate the potential clinical significance of the exon 1 polymorphism, 21 patients with angioedema and C1 inhibitor deficiency were genotyped. None were homozygous for the (+)21-29 allele (p = 0.0088 compared with normal subjects). In contrast, two patients with immunochemical evidence of hereditary angioedema without history of clinical angioedema were (+)21-29 homozygous. These results suggest that the B2BKR genotype may influence clinical status in diseases characterized by involvement of bradykinin.