Hereditäres Angioödem durch C1-Inhibitor-Mangel

[Drug-induced angioedema : Focus on bradykinin]

On a pathophysiological level, angioedema can be differentiated into histamine- and bradykinin-mediated types. The prototype drug-associated, bradykinin-mediated form of angioedema is angiotensin-converting enzyme (ACE) inhibitor-induced angioedema. The hypothesized cause is a decrease in bradykinin degradation via ACE inhibition. In this scenario, other bradykinin-degrading enzymes assume major importance. When the effect of these enzymes is also diminished, e. g., due to genetic variants or external factors, compensation for the inhibition of ACE may be insufficient. An increased risk of angioedema has also been reported for other drugs, particularly when prescribed in combination with ACE inhibitors. Here, the suspected cause also relates to the degradation of bradykinin. When angioedema arises within the context of concomitant ACE inhibitor use, additive bradykinin degradation effects may be implicated.

Hoffmann T, Bock B, Nordmann-Kleiner M, Trainotti S, Greve J. Angioedema

BACKGROUND

Acute angioedema of the upper airways can be life-threatening. An important distinction is drawn between mast-cell-mediated angioedema and bradykinin-mediated angioedema; the treatment of these two entities is fundamentally different.

METHODS

This review is based on pertinent articles retrieved by a selective search in PubMed and on guidelines concerning the treatment of angioedema. The authors draw on their own clinical experience in their assessment of the literature.

RESULTS

In the emergency clinical situation, the most important information comes from accompanying manifestations such as itching and urticaria and from the patient's drug history and family history. When angioedema affects the head and neck, securing the upper airways is the highest priority. Angioedema is most commonly caused by mast-cell mediators, such as histamine. This type of angioedema is sometimes accompanied by urticaria and can be effectively treated with antihistamines or glucocorticoids. In case of a severe allergic reaction or anaphylaxis, epinephrine is given intramuscularly in a dose that is adapted to the patient's weight (150 μg for body weight >10 kg, 300 μg for body weight >30 kg). Bradykinin-mediated angioedema may arise as either a hereditary or an acquired tendency. Acquired angioedema can be caused by angiotensin converting enzyme (ACE) inhibitors and by angiotensin II receptor blockers. Bradykinin-mediated angioedema should be treated specifically with C1-esterase inhibitor concentrates or bradykinin-2 receptor antagonists.

CONCLUSION

Angioedema of the upper airways requires a well-coordinated diagnostic and therapeutic approach. Steroids and antihistamines are very effective against mast-cell-mediated angioedema, but nearly useless against bradykinin-mediated angioedema. For angioedema induced by ACE inhibitors, no causally directed treatment has yet been approved.

Prophylaxis in hereditary angioedema (HAE) with C1 inhibitor deficiency

Hereditary angioedema (HAE) is a rare congenital disorder characterized by recurrent episodes of subcutaneous or submucosal edema. Laryngeal manifestations can be life-threatening. In the majority of cases, the disease can be adequately treated with an on-demand approach--in some cases, however, short- or long-term prophylaxis is indicated. Attenuated androgens used to be the drugs of choice, but they are associated with considerable side effects and no longer commercially available in the German-speaking countries of the EU. They are currently being replaced by more effective and more tolerable agents such C1-inhibitors, the kallikrein inhibitor ecallantide, and the B2 receptor antagonist icatibant, which have recently obtained market authorization. These new drugs have had a major impact, especially on the indications and procedures for long-term prophylaxis. According to the most recent international consensus papers and our own experience, self-administered C1-inhibitors are now the first option for long-term prophylactic therapy. The decision for prophylaxis should no longer be based on single parameters such as the frequency of attacks but on adequate overall disease control including quality of life. More drugs are currently being developed, which may lead to further changes in the treatment algorithms of HAE.

[Bradykinin-induced angioedema: Definition, pathogenesis, clinical presentation, diagnosis and therapy]

The incidence of bradykinin-induced angioedema is considerably lower than that of histamine-induced forms; however, the same is true for the clinician's knowledge of this condition. Bradykinin-induced angioedemas include hereditary angioedema (HAE), as well as acquired forms induced by drugs or antibody formation, e.g., during the course of oncologic disease. Drug-induced forms affect almost exclusively the head and neck region, and are thus important for the otorhinolaryngologist. Clear differentiation between histamine-induced angioedema (e. g., connected to allergy/urticaria) and bradykinin-induced angioedema is essential for selection of the specific treatment and may be lifesaving. Antihistamines and cortisone derivatives have no relevant effect in bradykinin induced-angioedema, whereas blood-derived C1 esterase inhibitor and bradykinin receptor 2 antagonists represent effective therapeutic options--both for acute and prophylactic treatment.

[Mucosal diseases from an allergological perspective]

The oral allergy syndrome is one of the most common form of food allergy and manifests as contact urticaria of the oral mucosa after consumption of cross reacting foods. Whereas allergic contact stomatitis often occurs due to dental materials, allergic contact cheilitis is usually a reaction due to topical therapeutics like herpes ointments or lip care products. As late type reactions are more frequent than immediate type reactions in the anogenital mucosa, contact dermatitis in this area should be identified via epicutaneous testing. In case of contact urticaria at the genital mucosa, a semen allergy or a latex allergy should be given due consideration as a possible cause. Angioedemas, which are mostly common histamine mediated, usually prefer skin areas with loose connective tissue such as the oral or genital mucosa. Fixed drug eruption also occurs preferentially in these areas. Bullous drug-induced skin reactions (e.g., SJS and TEN) are characterized by severe hemorrhagic, erosive affections of mucous membranes.

Nanofiltrated C1-esterase-inhibitor in the prophylactic treatment of bradykinin-mediated angioedema

BACKGROUND

Patients suffering from bradykinin-induced angioedema show recurrent swelling of subcutaneous and submucosal structures. Increased bradykinin levels lead to an increase in vascular permeability and edema formation. Current therapy consists of B2 bradykinin receptor antagonists, C1-esterase-inhibitor (C1-INH) concentrate, or the kallikrein inhibitor ecallantide. In most cases the treatment of acute attacks is sufficient. Prophylactic therapy is recommended only in severe cases. C1-INHc has been shown a safe and efficient option. Its effect on the quality of life has not yet been analyzed.

STUDY DESIGN AND METHODS

Patients with inadequate disease control despite an "on-demand therapy" including C1-INHc and/or the B2 receptor antagonist icatibant were switched to long-term prophylaxis consisting in an individual dose of intravenous C1-INHc (Cinryze). None of the patients had been previously treated with ecallantide. Disease-specific quality-of-life questionnaires and patient records were used for evaluation. Disease control, quality of life, adverse events, and administered dosage per month were compared for 6 months on on-demand therapy and the following 6 months under prophylactic therapy.

RESULTS

Data of seven patients with hereditary angioedema (HAE) and one patient with acquired angioedema were evaluated. Prophylactic therapy with Cinryze led to a significant and clinically relevant reduction in the overall attack frequency from 6.7 to 2.3 per month without relevant side effects. The frequency of severe attacks was reduced by 89% and quality of life significantly improved.

CONCLUSION

Prophylaxis with Cinryze led to a significantly improved quality of life in our cohort of patients with high-frequency bradykinin-induced angioedema attacks that were not sufficiently treated with on-demand medication.

Urticaria

Urticaria is a very common skin disease which was already described in the ancient world. Questions still remain about its pathogenesis and management remain open. Compared to other common skin diseases, the published evidence is rather low. The clinical symptoms with pruritic transient wheals and/or angioedema are caused by mediators (particularly histamine) released by activated mast cells and basophils. The mechanism of target cell activation has not been clarified in detail for most urticaria subtypes. Different urticaria subtypes should be distinguished. Spontaneous forms are more common than inducible forms. Chronic urticaria and urticaria in certain age groups (children, pregnancy) can be difficult to manage. Therefore, international consensus resulting in the regular update of urticaria guidelines can be very helpful. Currently, these updated guidelines include a three-step treatment algorithm for chronic spontaneous urticaria. Only the first step of this algorithm, second generation H1-antihistamine in standard dose, utilized approved drugs. However after omalizumab was established as a third line choice in the guideline algorithm, it has approved in many countries for chronic spontaneous urticaria without response to H1-antihistamines. The exact mechanism of action of omalizumab in urticaria has not been fully elucidated. Unrevealing this mechanism might result in a deeper understanding of urticaria pathogenesis and the development of further therapeutic strategies.

Komplementsystem und Komplementdefekte

Unter den Mechanismen, die zum Selbstschutz des Körpers beitragen, ist das Komplementsystem von herausragender Bedeutung. Als Teil der angeborenen Abwehr ist es jederzeit verfügbar und somit bereits in der Präimmunphase von unschätzbarem Wert, bevor es zur Bereitstellung spezifischer Antikörper und T-Lymphozyten kommt. Zu seinen Effektorfunktionen zählen neben der lytischen Zerstörung pathogener Mikroorganismen die Beseitigung von Immunkomplexen, die Opsonisierung nicht nur von Krankheitserregern, sondern auch von autoantigenem Material für eine effiziente Phagozytose sowie die Rekrutierung und Aktivierung von Entzündungszellen. Darüber hinaus moduliert das Komplementsystem aber auch die Antwort des erworbenen Immunsystems. Außerdem wird in zunehmendem Maße die Rolle des Komplementsystems in so unterschiedlichen biologischen Prozessen wie der Hämatopoese, Fortpflanzung und der Organregeneration deutlich, so dass die Vorstellung von Komplement als reinem Abwehrsystem erweitert werden muss zu einem mit vielen biologischen Funktionen vernetzten und steuernden System zur Aufrechterhaltung der Homöostase.

Etwa 5 % aller Plasmaproteine sind Komplementfaktoren, die zum überwiegenden Teil in der Leber und durch Makrophagen synthetisiert werden. Aber auch Fibroblasten, Epithelzellen der Lunge und des Magen-Darmtraktes und weitere Gewebszellen, wie Astrozyten, Haut-und Muskelzellen, sind prinzipiell zur Synthese zumindest bestimmter Komplementproteine fähig.