Abstract
BackgroundAngioedema without wheals (AE) is a symptom characterised by localised episodes of oedema presumably caused by kinin release from kininogen cleavage. It can result from a hereditary deficiency in C1 Inhibitor (C1Inh), but it can present with normal level of C1Inh. These forms are typically difficult to diagnose although enhanced kinin production is suspected or demonstrated in some cases.ObjectivesWe wanted to investigate bradykinin overproduction in all AE condition with normal C1Inh, excluding cases with enhanced kinin catabolism, and to propose this parameter as a disease biomarker.MethodsWe retrospectively investigated high molecular weight kininogen (HK) cleavage pattern, using gel electrophoresis and immunorevelation. Plasma samples were drawn using the same standardised procedure from blood donors or AE patients with normal C1Inh conditions, normal kinin catabolism, and without prophylaxis.ResultsCirculating native HK plasma concentrations were similar in the healthy men (interquartile range: 98–175μg/mL, n = 51) and in healthy women (90–176μg/mL, n = 74), while HK cleavage was lower (p<0.001) in men (0–5%) than women (3–9%). Patients exhibited lower native HK concentration (p<10−4; 21–117μg/mL, n = 31 for men; 0–84μg/mL, n = 41 for women) and higher HK cleavage (p<10−4; 10–30% and 14–89%, respectively) than healthy donors. Pathological thresholds were set at: <72μg/mL native HK, >14.4% HK cleavage for men; <38μg/mL; native HK, >33.0% HK cleavage for women, with >98% specificity achieved for all parameters. In plasma from patients undergoing recovery two months after oestrogen/progestin combination withdrawal (n = 13) or two weeks after AE attack (n = 2), HK cleavage was not fully restored, suggesting its use as a post-attack assay.ConclusionAs a diagnostic tool, HK cleavage can offer physicians supportive arguments for kinin production in suspected AE cases and improve patient follow-up in clinical trials or prophylactic management.
Highlights
Angioedema manifests as self-limiting oedema affecting the subcutaneous and sub-mucosal tissues
In Factor XII-related Angioedema without wheals (AE) (FXII-AE), causative mutations have been identified in the Factor XII encoding gene (OMIM 610618) [1,9,10,11], leading to pathological BK production [12]
Since BK is degraded by several peptidases, including angiotensin-converting enzyme (ACE), ACE inhibitor treatment can trigger AE (ACEi-AE, OMIM 300909) [1,5,18] but other BK degrading peptidases might be implicated [2,18]
Summary
Angioedema manifests as self-limiting oedema affecting the subcutaneous and sub-mucosal tissues It is most commonly associated with wheals in conjunction with urticaria, an histamine mediated-, mast cell degranulation related disease [1,2]. Angioedema without wheals (AE) is a symptom characterised by localised episodes of oedema presumably caused by kinin release from kininogen cleavage. It can result from a hereditary deficiency in C1 Inhibitor (C1Inh), but it can present with normal level of C1Inh. It can result from a hereditary deficiency in C1 Inhibitor (C1Inh), but it can present with normal level of C1Inh These forms are typically difficult to diagnose enhanced kinin production is suspected or demonstrated in some cases
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