Medical Literature - 2005

A direct role for C1 inhibitor in regulation of leukocyte adhesion

Cai S, Dole VS, Bergmeier W, Scafidi J, Feng H, Wagner DD, et al 5/2005 Journal of Immunology

Plasma C1 inhibitor (C1INH) is a natural inhibitor of complement and contact system proteases. Heterozygosity for C1INH deficiency results in hereditary angioedema, which is mediated by bradykinin. Treatment with plasma C1INH is effective not only in patients with hereditary angioedema, but also in a variety of other disease models, in which such therapy is accompanied by diminished neutrophil infiltration. The underlying mechanism has been explained primarily as a result of the inhibition of the complement and contact systems. We have shown that C1INH expresses the sialyl-Lewis(x) tetrasaccharide on its N-linked glycan, via which it binds to E- and P-selectins and interferes with leukocyte-endothelial adhesion in vitro. Here we show that both native C1INH and reactive center cleaved C1INH significantly inhibit selectin-mediated leukocyte adhesion in several in vitro and in vivo models, whereas N-deglycosylated C1INH loses such activities. The data support the hypothesis that C1INH plays a direct role in leukocyte-endothelial cell adhesion, that the activity is mediated by carbohydrate, and that it is independent of protease inhibitory activity. Direct involvement of C1INH in modulation of selectin-mediated cell adhesion may be an important mechanism in the physiologic suppression of inflammation, and may partially explain its utility in therapy of inflammatory diseases.

May 15;174(10):6462-6466

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A phase I study of recombinant human C1 inhibitor in asymptomatic patients with hereditary angioedema

van Doorn MB, Burggraaf J, van Dam T, Eerenberg A, Levi M, Hack CE, et al 10/2005 Journal of Allergy & Clinical Immunology

BACKGROUND: Hereditary angioedema (HAE) is a congenital disorder with recurrent attacks of localized swelling of submucosal tissue, subcutaneous tissue, or both caused by a deficiency of the plasma protein C1 inhibitor (C1 esterase inhibitor [C1INH]).

OBJECTIVE: We sought to evaluate the effects of recombinant human C1INH (rhC1INH) isolated from the milk of transgenic rabbits in 12 asymptomatic patients with HAE.

METHODS: rhC1INH was intravenously administered at doses of 6.25 to 100 U/kg on 2 occasions.

RESULTS: rhC1INH appeared safe and was well tolerated. The course of functional C1INH in plasma showed a full initial recovery (dose-normalized maximum concentration of about 0.02 U/mL/U/kg) and a dose-dependent clearance of rhC1INH. After infusion of rhC1INH at 100 U/kg, a clearance of approximately 13 mL/min, a half-life of approximately 3 hours, and a volume of distribution of approximately 3 L were observed. Infusion at this dose led to functional C1INH levels in plasma of at least twice the normal level for about 2 hours and greater than 0.4 U/mL for about 9 hours. rhC1INH displayed dose-dependent biologic activity by increasing the C4 level, which was about 2-fold at 12 hours after rhC1INH at 100 U/kg, and decreasing levels of cleaved C4.

CONCLUSION: The observed safety profile and biologic activity of rhC1INH warrants further clinical studies to assess its efficacy in treating HAE attacks.


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Adverse effects of danazol prophylaxis on the lipid profiles of patients with hereditary angioedema

Szeplaki G, Varga L, Valentin S, Kleiber M, Karadi I, Romics L, et al 4/2005 Journal of Allergy & Clinical Immunology

BACKGROUND: Hereditary angioedema (HAE) is a rare disorder caused by the deficiency of the C1-inhibitor gene (C1INH) . Patients experience recurrent bouts of edema, which can occur in almost any region of the body. As regards the treatment of the disease, danazol (an attenuated androgen) is used, among other agents, for long-term prophylaxis.

OBJECTIVE: The aim of this study was to investigate the possible adverse effects of danazol on serum lipid profile, as well as to ascertain whether danazol treatment is associated with an increased risk of atherosclerosis.

METHODS: Serum concentrations of total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides, apolipoprotein A-I, apolipoprotein B-100, and lipoprotein(a) were compared between danazol-treated patients with HAE and 2 control groups (ie, patients who did not receive long-term danazol prophylaxis and untreated healthy subjects).

RESULTS: Serum concentrations of HDL ( P = .0002 and P < .0001) and apolipoprotein A-I ( P = .0015 and P < .0001) were significantly lower, whereas LDL ( P = .0129 and P = .0127) and apolipoprotein B-100 ( P = .0456 and P = .0013) were higher in the danazol-treated patients compared with the 2 control groups, respectively. No significant difference was found in total cholesterol, triglyceride, or lipoprotein(a) levels. Patients who received danazol had an 11.6 (95% CI, 2.7-49.7) times higher risk for abnormally low HDL levels and a 4.4 (95% CI, 1.2-16.0) times lower risk for high LDL concentrations.

CONCLUSIONS: Our findings indicate that the long-term use of danazol is associated with an increased risk for early atherosclerosis in patients with HAE. Consequently, monitoring of HDL and LDL levels at regular intervals is recommended during follow-up.


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Kaplan AP, Greaves MW 9/2005 Journal of the American Academy of Dermatologya (Journal of the American Academy of Dermatologya (J.Am.Acad.Dermatol.)

UNLABELLED: Although first described more than 130 years ago, the pathophysiology, origin, and management of the several types of angioedema are poorly understood by most dermatologists. Although clinically similar, angioedema can be caused by either mast cell degranulation or activation of kinin formation. In the former category, allergic and nonsteroidal anti-inflammatory drug-induced angioedema are frequently accompanied by urticaria. Idiopathic chronic angioedema is also usually accompanied by urticaria, but can occur without hives. In either case, an autoimmune process leading to dermal mast cell degranulation occurs in some patients. In these patients, histamine-releasing IgG anti-FcepsilonR1 autoantibodies are believed to be the cause of the disease, removal or suppression by immunomodulation being followed by remission. Angiotensin-converting enzyme inhibitor-induced angioedema is unaccompanied by hives, and is caused by the inhibition of enzymatic degradation of tissue bradykinin. Hereditary angioedema, caused by unchecked tissue bradykinin formation, is recognized biochemically by a low plasma C’4 and low quantitative or functional C’1 inhibitor. Progress has now been made in understanding the molecular genetic basis of the two isoforms of this dominantly inherited disease. Recently, a third type of hereditary angioedema has been defined by several groups. Occurring exclusively in women, it is not associated with detectable abnormalities of the complement system. Angioedema caused by a C’1 esterase inhibitor deficiency can also be acquired in several clinical settings, including lymphoma and autoimmune connective tissue disease. It can also occur as a consequence of specific anti-C’1 esterase autoantibodies in some patients. We have reviewed the clinical features, diagnosis, and management of these different subtypes of angioedema. LEARNING OBJECTIVE: After completing this learning activity, participants should be aware of the classification, causes, and differential diagnosis of angioedema, the molecular basis of hereditary and non-hereditary forms of angioedema, and be able to formulate a pathophysiology-based treatment strategy for each of the subtypes of angioedema. [References: 115].

quiz 389-92; Sep;53(3):373-388

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Basic and clinical immunology

Chinen J, Shearer WT 8/2005 Journal of Allergy & Clinical Immunology

The authors selected articles published in the literature from January 2004 through December 2004 that were relevant to the areas of basic and clinical immunology. Several articles explored the development of TH1 or TH2 response and the role of the monocyte-T cell interaction. Others were articles describing the action of drugs commonly used in asthma to inhibit cytokine responses and the anti-inflammatory role of nonimmune pulmonary cells present in the lung. Several reports show how dendritic cells are being developed as vehicles for DNA vaccines aimed at stimulating cellular responses, an advance of great importance for HIV researchers working on vaccines, who are concerned about the different ways HIV evades the immune response. Other publications described Toll-like receptors in diverse cells, including mast cells and CD4+ T cells, for the recognition of viruses and bacteria. In the area of clinical immunology, an updated classification for primary immunodeficiencies with more than 100 identified genes responsible for these diseases and the report on the second clinical trial of gene therapy for X-linked severe combined immunodeficiency syndrome were published. Significant advances included the clinical prognosis in common variable immunodeficiency for patients presenting with lung pathology, the safety of live vaccines in partial DiGeorge syndrome, the report of patients with complete DiGeorge syndrome with the presence of peripheral blood T cells, the clinical spectrum of patients with NF-kappaB essential modifier (NEMO) gene deficiency, the publication of a consensus algorithm for the management of hereditary angioedema, and the report of immune restoration syndrome in pediatric HIV infection. [References: 54].


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C1 inhibitor deficiency: consensus document

Gompels MM, Lock RJ, Abinun M, Bethune CA, Davies G, Grattan C, et al 3/2005 Clinical & Experimental Immunology

We present a consensus document on the diagnosis and management of C1 inhibitor deficiency, a syndrome characterized clinically by recurrent episodes of angio-oedema. In hereditary angio-oedema, a rare autosomal dominant condition, C1 inhibitor function is reduced due to impaired transcription or production of non-functional protein. The diagnosis is confirmed by the presence of a low serum C4 and absent or greatly reduced C1 inhibitor level or function. The condition can cause fatal laryngeal oedema and features indistinguishable from gastrointestinal tract obstruction. Attacks can be precipitated by trauma, infection and other stimulants. Treatment is graded according to response and the clinical site of swelling. Acute treatment for severe attack is by infusion of C1 inhibitor concentrate and for minor attack attenuated androgens and/or tranexamic acid. Prophylactic treatment is by attenuated androgens and/or tranexamic acid. There are a number of new products in trial, including genetically engineered C1 esterase inhibitor, kallikrein inhibitor and bradykinin B2 receptor antagonist. Individual sections provide special advice with respect to diagnosis, management (prophylaxis and emergency care), special situations (childhood, pregnancy, contraception, travel and dental care) and service specification. [References: 138].


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Current and future therapy for hereditary angioedema

Zuraw BL 1/2005 Clinical Immunology

Hereditary angioedema (HAE) is an autosomal dominant disease characterized by recurrent episodes of potentially life-threatening angioedema. Attacks of angioedema in HAE patients typically last 3 or more days, begin during childhood, and continue to occur throughout life. Tragically, patients with HAE continue to die as a direct consequence of the disease. Minimizing the morbidity and mortality associated with HAE requires both effective treatment of acute attacks as well as strategies to prevent HAE attacks. While there is currently no effective therapy available in the United States for the treatment of acute attacks of HAE, several molecules have demonstrated impressive efficacy in this setting, and it is likely that one or more of these new drugs will become available in the United States soon. This article will review both the current and the future therapeutic options for the treatment of HAE. [References: 63].


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Emergency treatment of acute attacks in hereditary angioedema due to C1 inhibitor deficiency: what is the evidence?

Longhurst HJ 5/2005 Int.J.Clin.Pract.

Hereditary angioedema (HAE) is caused by a deficiency in C1 esterase-inhibitor (C1-INH) and is characterised by skin swelling, abdominal pain and episodes of upper respiratory tract obstruction. Oedema of the larynx can result in rapid asphyxiation and requires emergency treatment. Three treatment options for emergency treatment of HAE are reviewed: fresh frozen plasma, solvent/detergent-treated plasma and C1-INH concentrate. It is concluded that while all three treatment options are theoretically effective in the emergency treatment of HAE, C1-INH is the treatment of choice. [References: 31].


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Hereditary angioedema

Frank MM 12/2005 Immunology & Allergy Clinics of North America

PURPOSE OF REVIEW: Major advances have been made in understanding the clinical signs and symptoms, the pathophysiology and the treatment of hereditary angioedema. This disease that often begins in childhood is caused by partial absence of the plasma protein C1-inhibitor. At the present time five pharmaceutical companies are planning or conducting clinical trials of a variety of agents to treat acute attacks of this illness. Here we review our current understanding of this illness and the current approaches to treatment.

RECENT FINDINGS: This disease is often missed in childhood or confused with other illness. The clinical signs and symptoms are reviewed. The importance of the kinin generating pathway and bradykinin in causing edema has become central to our understanding of pathophysiology. The many new approaches to therapy all appear promising.

SUMMARY: Currently we have effective chronic therapy for this disease, although available drugs have real or potential difficulties in use in children. In the future it is likely that effective therapy for acute attacks of disease will become available in the US. It is important to recognize the clinical manifestations of this potentially fatal illness and to understand the therapeutic options. [References: 31].


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Treatment with C1 inhibitor concentrate in abdominal pain attacks of patients with hereditary angioedema

Bork K, Meng G, Staubach P, Hardt J 11/2005 Transfusion

BACKGROUND: Abdominal edema attacks in patients with hereditary angioedema are often extremely painful, associated with vomiting and diarrhea, and have a high potential for causing recurrent disability of the patient. STUDY DESIGN AND METHODS: Intraindividual comparison of retrospective data in 75 hereditary angioedema patients comprising 4,834 abdominal attacks treated with C1 inhibitor concentrate versus 17,444 untreated abdominal attacks. RESULTS: The mean duration of abdominal attacks was 92.0 hours (SD, 40.8 hr) when untreated compared to 39.9 hours (SD, 30.0 hr) when treated. Patients reported a mean maximal pain score of 8.6 (SD, 1.7; range, 1-10) for untreated attacks compared to 4.5 (SD, 2.9) when treated. Vomiting occurred in 83.3 percent of untreated attacks and in 6.0 percent of treated attacks, respectively. Diarrhea was reported in 41.8 percent of untreated attacks and in 11.0 percent of treated attacks, whereas cardiovascular collapse due to hypovolemia was observed in 3.5 percent of untreated attacks versus 0.1 percent in treated attacks. Mean time to relief of symptoms was 53.5 minutes when treated early compared to 114 minutes when treatment was delayed. No drug-related adverse or serious adverse events were observed as far as the injections were performed correctly. CONCLUSION: C1 inhibitor concentrate is highly effective and safe in treating abdominal attacks in patients suffering from hereditary angioedema.


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Funding for Canadian Hereditary Angioedema Network has been generously provided by unrestricted grants from:


CSL Behring


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