Massimo Cugno

Plasma bradykinin in angio-oedema

BACKGROUND Bradykinin is believed to be the main mediator of symptoms in hereditary (HA) and acquired (AA) angio-oedema due to C1 esterase inhibitor deficiency, as well as in angio-oedema that complicates treatment with inhibitors of angiotensin-converting enzyme (ACE). Difficulties in the measurement of kinin concentrations, however, have so far precluded the demonstration of an incontrovertible change in plasma bradykinin concentrations in these disorders. By developing a reliable assay we have been able to follow bradykinin concentrations during attacks and during remission in HA and in AA, and also in a patient treated with an ACE-inhibitor. METHODS Liquid-phase extraction, high-performance liquid chromatography, and RIA were used for specific measurement of plasma bradykinin concentrations in 22 patients with HA and in 22 healthy volunteers of similar age and sex distribution. Four patients with AA and one hypertensive patient treated with the ACE inhibitor captopril were also studied. FINDINGS Among the healthy volunteers plasma bradykinin concentration was inversely proportional to age. The geometric mean plasma bradykinin concentration in the healthy volunteers was 2.2 fmol/mL (SD 2.2), compared with 3.9 fmol/mL (3.7) among patients with HA during remission (p=0.095). Bradykinin was also high in the patients with AA (10.4 fmol/mL [1.6]). During acute attacks of oedema, in both HA and AA, plasma bradykinin rose to two to 12 times the upper limit of normal. Infusion of C1-esterase inhibitor (the deficient factor in both HA and AA) immediately lowered bradykinin concentrations. In the patient receiving the ACE-inhibitor captopril, bradykinin concentration was very high at 47 fmol/mL during an acute attack of angio-oedema, but normal at 3.2 fmol/mL in remission after withdrawal of the drug. INTERPRETATION A sensitive method for measurement of plasma bradykinin provided the means to show that concentrations of this peptide decrease with age in healthy people. Although the differences between patients in remission and healthy controls did not reach statistical significance, there were substantial rises in bradykinin during acute attacks of hereditary, acquired, or captopril-induced angio-oedema.

Bradykinin-Mediated Angioedema

To the Editor: Angioedema is a nonitchy, pale swelling of subcutaneous or submucosal tissue that tends to recur chronically and can become life-threatening if the swelling occurs in the upper airwa...

Bradykinin and the pathophysiology of angioedema

Angioedema has different causes and different clinical presentations. Some types of angioedema may be mediated by bradykinin. We measured plasma levels of bradykinin-(1-9)nonapeptide by radioimmunoassay after high-performance liquid chromatography in patients with different types of angioedema during acute attacks and/or in remission, i.e. hereditary C1-inhibitor deficiency, angiotensin converting enzyme (ACE) inhibitor treatment, idiopathic non histaminergic and responders to antihistamines. Eleven patients with the deficiency of C1-inhibitor had very high levels of bradykinin during acute attacks of angioedema (18.0-90.0 pM) (normal range 0.2-7.1 pM). In three patients with history of ACE inhibitor-related angioedema, plasma bradykinin was high during ACE inhibitor treatment (62.0, 8.9 and 27.0 pM) and in a fourth patient was 47.0 pM during an acute attack and decreased by 93% to 3.2 pM after withdrawal of the ACE inhibitor. The patient with idiopathic angioedema, during an acute attack involving the right arm, had high levels of bradykinin in the venous blood refluent from the angioedematous arm (20.0 pM) while in the contralateral arm bradykinin levels were normal (6.6 pM), similarly to what we previously observed in cases of brachial angioedema due to C1-inhibitor deficiency. The four patients with angioedema responsive to antihistamines had normal levels of bradykinin even during acute attacks (5.7, 3.4, 4.7 and 1.2 pM). In one of these patients who had a brachial angioedema, bradykinin levels were normal in the venous blood refluent from both arms. Bradykinin is involved in hereditary C1-inhibitor deficiency angioedema, in ACE inhibitor-related angioedema, and in idiopathic non-histaminergic angioedema, while bradykinin is not related to allergen-dependent or idiopathic angioedema that are responsive to antihistamines.

Aminopeptidase P in individuals with a history of angio-oedema on ACE inhibitors

Angio-oedema is a rare but potentially life threatening side-effect of angiotensin-converting-enzyme (ACE) inhibitor treatment. Identification of individuals at risk of this adverse effect is not possible. Angio-oedema is associated with raised concentrations of bradykinin, which is mainly inactivated by ACE. We assessed the plasma activity of two other enzymes that catabolise bradykinin (aminopeptidase P and carboxypeptidase N) in 39 hypertensive patients with a history of angio-oedema during ACE inhibitor treatment and in 39 hypertensive patients who had never had ACE inhibitor associated side-effects. Patients with previous angio-oedema had a lower plasma activity of aminopeptidase P than did those who never presented with angio-oedema (p=0 003). Our data suggest that low plasma concentrations of aminopeptidase P could be a predisposing factor for development of angio-oedema in patients treated with ACE inhibitors.

C1-inhibitor deficiency and angioedema: molecular mechanisms and clinical progress

C1 inhibitor (C1-INH, also known as SERPING1) can be deficient in plasma as a result of genetic or acquired conditions, and this causes an episodic, local increase in vascular permeability in the subcutaneous and submucosal layers, identified as angioedema (hereditary or acquired). Bradykinin, the mediator of the increase in vascular permeability, is released on inappropriate activation of the contact system, which is controlled by C1 inhibitor. Therapy aims to reverse or prevent angioedema. Advances in understanding the complex effects of C1-INH deficiency at the molecular level have led to new molecular-targeted approaches. Three new treatments, an inhibitor of kallikrein to prevent bradykinin release, an antagonist of the bradykinin receptor to prevent its action and a recombinant human C1-INH produced in transgenic animals, are under clinical evaluation currently. Here, we review the molecular mechanisms underlying angioedema due to C1-inhibitor deficiency and clinical progress using molecular-targeted interventions.

Angioedema due to angiotensin-converting enzyme inhibitors.

Angiotensin-converting enzyme (ACE) inhibitor associated angioedema was detected in 39 subjects (17%) of 231 consecutive patients examined in the last 5 years at our out-patient clinic for symptoms of angioedema without urticaria. In these patients, angioedema was most commonly localized to the face. The duration of ACE-inhibitor treatment at the onset of angioedema ranged from 1 day to 8 years with a median of 6 months. The time elapsed between onset of angioedema and withdrawal of ACE-inhibitor ranged from 1 day to 10 years with a median of 10 months. Delayed diagnosis is explained by the unusual characteristics of this adverse reaction: angioedema may start years after beginning the treatment and then it recurs irregularly. In fact, ACE-inhibitors seem to facilitate angioedema in predisposed subjects, rather than causing it with an allergic or idiosyncratic mechanism. Thus, while Cl-inhibitor levels are usually normal in subjects developing ACE-inhibitor-dependent angioedema, we found that ACE-inhibitors caused angioedema in Cl-inhibitor-deficient patients. Because the main inactivator of bradykinin is kininase II, which is identical with ACE, it is believed that bradykinin mediates ACE-inhibitor-dependent angioedema. We had the possibility to examine the plasma bradykinin levels in one ACE-inhibitor-treated patient during an angioedema attack and we found very high levels, but we did not find an increase of break-down products of high-molecular-weight-kininogen as observed during acute attacks in hereditary angioedema. Bradykinin fell to normal levels during remission after withdrawal of the drug. These observations indicate that in ACE-inhibitor-induced angioedema, contrary to hereditary angioedema, the reduction of bradykinin catabolic rate plays a predominant role.

Expression of cytokines, chemokines and other effector molecules in two prototypic autoinflammatory skin diseases, pyoderma gangrenosum and sweet's syndrome

Pyoderma gangrenosum (PG) and Sweets syndrome (SS) are two inflammatory skin diseases presenting with painful ulcers and erythematous plaques, respectively; both disorders have a debilitating clinical behaviour and PG is potentially life‐threatening. Recently, PG and SS have been included among the autoinflammatory diseases, which are characterized by recurrent episodes of sterile inflammation, without circulating autoantibodies and autoreactive T cells. However, an autoinflammatory pattern clearly supporting this inclusion has never been demonstrated. We studied 16 patients with PG, six with SS and six controls, evaluating, using a sandwich‐based protein antibody array method, the expression profile of inflammatory effector molecules in PG, SS and normal skin. The expressions of interleukin (IL)‐1 beta and its receptor I were significantly higher in PG (P = 0·0001 for both) and SS (P = 0·004–0·040) than in controls. In PG, chemokines such as IL‐8 (P = 0·0001), chemokine (C‐X‐C motif) ligand (CXCL) 1/2/3 (P = 0·002), CXCL 16 (P = 0·003) and regulated upon activation normal T cell expressed and secreted (RANTES) (P = 0·005) were over‐expressed. In SS, IL‐8 (P = 0·018), CXCL 1/2/3 (P = 0·006) and CXCL 16 (P = 0·036) but not RANTES were over‐expressed, suggesting that chemokine‐mediated signals are lower than in PG. Fas/Fas ligand and CD40/CD40 ligand systems were over‐expressed in PG (P = 0·0001 for Fas, P = 0·009 for Fas ligand, P = 0·012 for CD40, P = 0·0001 for CD40 ligand), contributing to tissue damage and inflammation, while their role seems to be less significant in SS. Over‐expression of cytokines/chemokines and molecules amplifying the inflammatory network supports the view that PG and SS are autoinflammatory diseases. The differences in expression profile of inflammatory effectors between these two disorders may explain the stronger local aggressiveness in PG than SS.

Long-term treatment of hereditary angioedema with attenuated androgens: a survey of a 13-year experience.

Fifty-six patients affected with hereditary angioedema have been followed during long-term prophylaxis with attenuated androgens. The treatment was started in patients who had one or more severe attacks per month. In 24 patients, the therapy lasted for more than 5 years. The minimal effective dose usually did not exceed 2 mg/day of stanozolol or 200 mg/day of danazol. Only in two patients were these doses not sufficient to achieve the complete disappearance of symptoms. Irregular menstruation, but rarely amenorrhea, was the only significant side effect. One patient had to stop the therapy because of laboratory signs of hepatic cell necrosis. In one patient, danazol was administered during the last 8 weeks of pregnancy without side effects for the mother but with transient signs of virilization for the female baby. To find a biochemical marker for the minimal effective dose of androgen derivatives, we measured the plasma levels of C1 C1 INH complexes at different doses of stanozolol in four patients with hereditary angioedema. We found that these complexes, elevated before treatment, promptly reverted to normal values during androgen therapy and remained normal with any reduction of the dose of the drug as long as the patient remained symptom free. Therefore, the measurement of C1 C1 INH complexes appears to reflect the activity of the disease and not the amount of androgen that is administered.

Discontinuation of Eculizumab Maintenance Treatment for Atypical Hemolytic Uremic Syndrome: A Report of 10 Cases

Atypical hemolytic uremic syndrome (aHUS) is a life-threatening thrombotic microangiopathy, and as many as 70% of patients with aHUS have mutations in the genes encoding complement regulatory proteins. Eculizumab, a humanized recombinant monoclonal antibody targeting C5, has been used successfully in patients with aHUS since 2009. The standard maintenance treatment requires life-long eculizumab therapy, but the possibility of discontinuation has not yet been tested systematically. We report the safety of discontinuing eculizumab treatment in 10 patients who stopped treatment with the aim of minimizing the risk of adverse reactions, reducing the risk of meningitis, and improving quality of life while also reducing the considerable treatment costs. Disease activity was monitored closely at home by means of urine dipstick testing for hemoglobin. During the cumulative observation period of 95 months, 3 of the 10 patients experienced relapse within 6 weeks of discontinuation, but then immediately resumed treatment and completely recovered. Our experience supports the possibility of discontinuing eculizumab therapy with strict home monitoring for early signs of relapse in patients with aHUS who achieve stable remission.

Role of inflammatory cells, cytokines and matrix metalloproteinases in neutrophil-mediated skin diseases

Pyoderma gangrenosum (PG) is a rare, immune‐mediated inflammatory skin disease presenting with painful ulcers having undermined edges. Less commonly, bullous and vegetative variants exist. Histology consists of a neutrophil‐rich dermal infiltrate. We characterized immunohistochemically the infiltrate in different variants of PG and in another neutrophilic dermatosis as Sweets syndrome. We studied 21 patients with PG, eight with Sweets syndrome and 20 controls, evaluating skin immunoreactivity for inflammatory cell markers (CD3, CD163 and myeloperoxidase), cytokines [tumour necrosis factor (TNF)‐α, interleukin (IL)‐8 and IL‐17], metalloproteinases (MMP‐2 and MMP‐9) and vascular endothelial growth factor (VEGF). Immunoreactivities of CD3, CD163, myeloperoxidase, TNF‐α, IL‐8, IL‐17, MMP‐2, MMP‐9 and VEGF were significantly higher in both PG and Sweets syndrome than in controls (P = 0·0001). Myeloperoxidase (neutrophil marker), IL‐8 (cytokine chemotactic for neutrophils) and MMP‐9 (proteinase‐mediating tissue damage) were expressed more significantly in both ulcerative and bullous PG than in vegetative PG as well as in Sweets syndrome (P = 0·008–P = 0·0001). In ulcerative PG, the expression of CD3 (panT cell marker) and CD163 (macrophage marker) were significantly higher in wound edge than wound bed (P = 0·0001). In contrast, the neutrophil marker myeloperoxidase was expressed more significantly in wound bed than wound edge (P = 0·0001). Our study identifies PG as a paradigm of neutrophil‐mediated inflammation, with proinflammatory cytokines/chemokines and MMPs acting as important effectors for the tissue damage, particularly in ulcerative and bullous PG where damage is stronger. In ulcerative PG, the wound bed is the site of neutrophil‐recruitment, whereas in the wound edge activated T lymphocytes and macrophages pave the way to ulcer formation.