Christian Drouet

Increased Activity of Coagulation Factor XII (Hageman Factor) Causes Hereditary Angioedema Type III

Hereditary angioedema (HAE) is characterized clinically by recurrent acute skin swelling, abdominal pain, and potentially life-threatening laryngeal edema. Three forms of HAE have been described. The classic forms, HAE types I and II, occur as a consequence of mutations in the C1-inhibitor gene. In contrast to HAE types I and II, HAE type III has been observed exclusively in women, where it appears to be correlated with conditions of high estrogen levels--for example, pregnancy or the use of oral contraceptives. A recent report proposed two missense mutations (c.1032C-->A and c.1032C-->G) in F12, the gene encoding human coagulation factor XII (FXII, or Hageman factor) as a possible cause of HAE type III. Here, we report the occurrence of the c.1032C-->A (p.Thr328Lys) mutation in an HAE type III-affected family of French origin. Investigation of the F12 gene in a large German family did not reveal a coding mutation. Haplotype analysis with use of microsatellite markers is compatible with locus heterogeneity in HAE type III. To shed more light on the pathogenic relevance of the HAE type III-associated p.Thr328Lys mutation, we compared FXII activity and plasma levels in patients carrying the mutation with that of healthy control individuals. Our data strongly suggest that p.Thr328Lys is a gain-of-function mutation that markedly increases FXII amidolytic activity but that does not alter FXII plasma levels. We conclude that enhanced FXII enzymatic plasma activity in female mutation carriers leads to enhanced kinin production, which results in angioedema. Transcription of F12 is positively regulated by estrogens, which may explain why only women are affected with HAE type III. The results of our study represent an important step toward an understanding of the molecular processes involved in HAE type III and provide diagnostic and possibly new therapeutic opportunities.

Intracellular complement activation sustains T cell homeostasis and mediates effector differentiation.

Summary Complement is viewed as a critical serum-operative component of innate immunity, with processing of its key component, C3, into activation fragments C3a and C3b confined to the extracellular space. We report here that C3 activation also occurred intracellularly. We found that the T cell-expressed protease cathepsin L (CTSL) processed C3 into biologically active C3a and C3b. Resting T cells contained stores of endosomal and lysosomal C3 and CTSL and substantial amounts of CTSL-generated C3a. While “tonic” intracellular C3a generation was required for homeostatic T cell survival, shuttling of this intracellular C3-activation-system to the cell surface upon T cell stimulation induced autocrine proinflammatory cytokine production. Furthermore, T cells from patients with autoimmune arthritis demonstrated hyperactive intracellular complement activation and interferon-γ production and CTSL inhibition corrected this deregulated phenotype. Importantly, intracellular C3a was observed in all examined cell populations, suggesting that intracellular complement activation might be of broad physiological significance.

Hereditary angioedema with normal C1 inhibitor function: consensus of an international expert panel.

A new form of hereditary angioedema (HAE) with normal C1 inhibitor (C1INH) was first described in 2000. The lack of clear diagnostic criteria, the heterogeneity among affected patients, and the varying names given to this disease have led to substantial confusion among both physicians and patients. This study was designed to bring more clarity to the diagnosis and potential treatment of HAE with normal C1INH. An international symposium of experts was convened to review the field and develop consensus opinions that could help clinicians who evaluate and manage these patients. Criteria were developed for the diagnosis of HAE with normal C1INH in patients with recurrent angioedema in the absence of concurrent urticaria. In addition, potential therapeutic strategies are discussed. The consensus criteria developed during this symposium will allow physicians to better diagnose and treat patients with HAE with normal C1INH.

Disease expression in women with hereditary angioedema

OBJECTIVE Fluctuations in sex hormones can trigger angioedema attacks in women with hereditary angioedema. Combined oral contraceptive therapies, as well as pregnancy, can induce severe attacks. The course of angioedema may be very variable in different women. STUDY DESIGN Within the PREHAEAT project launched by the European Union, data on 150 postpubertal women with hereditary angioedema were collected in 8 countries, using a patient-based questionnaire. RESULTS Puberty worsened the disease for 62%. Combined oral contraceptives worsened the disease for 79%, whereas progestogen-only pills improved it for 64%. During pregnancies, 38% of women had more attacks, but 30% had fewer attacks. Vaginal delivery was usually uncomplicated. Attacks occurred within 48 hours in only 6% of cases. Those more severely affected during menses had more symptoms during pregnancies, suggesting a hormone-sensitive phenotype for some patients. CONCLUSION The course of angioedema in women with C1 inhibitor deficiency is affected by physiologic hormonal changes; consequently, physicians should take these into account when advising on management.

Type III hereditary angio-oedema: clinical and biological features in a French cohort

To cite this article: Vitrat‐Hincky V, Gompel A, Dumestre‐Perard C, Boccon‐Gibod I, Drouet C, Cesbron JY, Lunardi J, Massot C, Bouillet L. Type III hereditary angio‐oedema: clinical and biological features in a French cohort. Allergy 2010; 65: 1331–1336.

Defective glycosylation of coagulation factor XII underlies hereditary angioedema type III

Hereditary angioedema type III (HAEIII) is a rare inherited swelling disorder that is associated with point mutations in the gene encoding the plasma protease factor XII (FXII). Here, we demonstrate that HAEIII-associated mutant FXII, derived either from HAEIII patients or recombinantly produced, is defective in mucin-type Thr309-linked glycosylation. Loss of glycosylation led to increased contact-mediated autoactivation of zymogen FXII, resulting in excessive activation of the bradykinin-forming kallikrein-kinin pathway. In contrast, both FXII-driven coagulation and the ability of C1-esterase inhibitor to bind and inhibit activated FXII were not affected by the mutation. Intravital laser-scanning microscopy revealed that, compared with control animals, both F12-/- mice reconstituted with recombinant mutant forms of FXII and humanized HAEIII mouse models with inducible liver-specific expression of Thr309Lys-mutated FXII exhibited increased contact-driven microvascular leakage. An FXII-neutralizing antibody abolished bradykinin generation in HAEIII patient plasma and blunted edema in HAEIII mice. Together, the results of this study characterize the mechanism of HAEIII and establish FXII inhibition as a potential therapeutic strategy to interfere with excessive vascular leakage in HAEIII and potentially alleviate edema due to other causes.

Induction of thioredoxin by ultraviolet-A radiation prevents oxidative-mediated cell death in human skin fibroblasts

The present study analyzes the expression of the thioredoxin/thioredoxin reductase (Trx/TR) system in UVA-irradiated human skin fibroblasts. Irradiation increases the intracellular level of Trx and a time-dependent increase of Trx mRNA is observed. Our data indicate that Trx translocates from the cytoplasm to the nucleus. In addition, UV exposure results in an increase in TR synthesis. In order to evaluate the function of Trx/TR system, we investigated the antioxidant role of Trx in transient transfected cells. The ROS accumulation in UVA irradiated cells was assessed using flow cytometry. A 3-fold decrease in ROS production was observed in transiently transfected fibroblasts. These results indicate that Trx acts as an antioxidant protein in UVA irradiated fibroblasts. As ROS are inducers of cell death, this raises the question as to whether Trx is able to protect cells from apoptosis and/or necrosis induced by UVA. Six hours after UVA-irradiation, 29.92% of cells were annexin-V positive. This population was significantly reduced in Trx-transfected cells (8.58%). Moreover, this work demonstrates that Trx prevents the loss of the membrane potential of the mitochondria, the depletion of cellular ATP content, and the loss of cell viability induced by irradiation.

BRADYKININ RECEPTOR 2 ANTAGONIST (ICATIBANT) FOR HEREDITARY ANGIOEDEMA TYPE III ATTACKS

In 2000, a new type of hereditary angioedema (HAE) without C1 esterase inhibitor (C1-INH) deficiency, HAE type III, was reported.1,2 It occurred especially in women, and the diagnosis was based on recurrent attacks of subcutaneous or submucosal edema, no chronic relapsing urticaria, familial history, and normal C1INH protein and activity levels. Recent findings3 suggest that bradykinin may play a role in the pathogenesis of angioedema. The morbidity and mortality of HAE are related to abdominal attacks and laryngeal edema. Symptoms seem to be induced or worsened by estrogen.4 In these patients, C1-INH function is normal, and a missense gain-of-function mutation in the F12 gene can be found.5 Treatments for HAE type III are not established, but tranexamic acid seems to be effective for prophylaxis of symptoms. Until recently, the main shortterm treatment for severe HAE attacks was C1-INH concentrate.4 A new therapeutic agent, icatibant, a bradykinin B2 receptor antagonist, is effective for the treatment of HAE with C1-INH deficiency. The efficacy and safety of icatibant in patients with HAE (type I or II) presenting with moderate to severe cutaneous or abdominal attacks were tested in 2 double-blind, randomized, multicenter, phase 3 trials, FAST (For Angioedema Subcutaneous Treatment) 1 and 2.6 We report treatment outcomes in 3 women who fulfilled the diagnosis criteria of HAE type III (Table 1). Patients presented with recurrent severe abdominal attacks, edema of the face, and a family history of angioedema. The C1-INH function was moderately low when the patients took an estrogen-containing contraceptive pill or during pregnancy but was normal after it was discontinued or after delivery. We previously described these data in another patient with HAE type III.7 Levels of C1-INH protein and C4 were normal. All 3 patients had no mutation in the SERPING1 gene. Patient 1 had an identified mutation in the F12 gene. Patient 1 received 1 subcutaneous injection of icatibant, 30 mg, for a severe abdominal attack. Symptom improvement began 30 minutes later, with complete resolution of symptoms by 1 hour after icatibant administration. Patient 2 presented with an unusual severe abdominal attack combined with facial edema. An increase in her dose of tranexamic acid did not improve symptoms. She received an injection of icatibant. Symptoms were relieved within 2 hours. Patient 3 was treated for a severe abdominal attack. After the first injection of icatibant, relief of symptoms occurred within 30 minutes. Symptom recurrence after 6 hours necessitated a second injection of icatibant, which resulted in rapid alleviation of symptoms. For all the patients, icatibant administration was followed by a transient local erythematic reaction at the site of injection. No other adverse reactions to icatibant were noted in the 3 patients. We therefore conclude that icatibant is a safe and effective symptomatic treatment for severe attacks in patients with HAE type III.

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.

A case of hereditary angio‐oedema type III presenting with C1‐inhibitor cleavage and a missense mutation in the F12 gene

1 Suzuki Y, Inagi R, Ando T et al. Human herpesvirus 6 infection as a risk factor for the development of severe drug-induced hypersensitivity syndrome. Arch Dermatol 1998; 134:1108–12. 2 Shiohara T, Inaoka M, Kano Y. Drug-induced hypersensitivity syndrome (DIHS): a reaction induced by a complex interplay among herpesviruses and antiviral and antidrug immune responses. Allergol Int 2006; 55:1–8. 3 Kano Y, Hirahara K, Sakuma K, Shiohara T. Several herpesviruses can reactivate in a severe drug-induced multiorgan reaction in the same sequential order as in graft-versus-host disease. Br J Dermatol 2006; 155:301–6. 4 Zaia JA. Viral infections associated with bone marrow transplantation. Hematol Oncol Clin North Am 1990; 4:603–23. 5 Zhang C, Todorov I, Zhang Z et al. Donor CD4+ T and B cells in transplants induce chronic graft-versus-host disease with autoimmune manifestations. Blood 2006; 107:2993–3001. 6 Ichiki Y, Bowlus CL, Shimoda S et al. T cell immunity and graftversus-host disease. Autoimmun Rev 2006; 5:1–9. 7 Jones-Caballero M, Fernandez-Herrera J, Cordoba-Guijarro S et al. Sclerodermatous graft-versus-host disease after donor leucocyte infusion. Br J Dermatol 1998; 139:889–92. 8 Schaffer JV, McNiff JM, Seropian S et al. Lichen sclerosus and eosinophilic fasciitis as manifestations of chronic graft-versus-host disease: expanding the sclerodermoid spectrum. J Am Acad Dermatol 2005; 53:591–601. 9 White JML, Devereux S, Pagliuca A et al. Koebnerizing sclerodermatous graft-versus-host disease caused by donor lymphocyte infusion and interferon-a. Br J Dermatol 2006; 155:621–3. 10 Chosidow O, Bagot M, Vernant JP et al. Sclerodermatous chronic graft-versus-host disease. Analysis of seven cases. J Am Acad Dermatol 1992; 26:49–55.