C. Blais et al., Serum metabolism of bradykinin and des-Arg(9)-bradykinin in patients with angiotensin-converting enzyme inhibitor-associated angioedema, IMMUNOPHARM, 43(2-3), 1999, pp. 293-302
Angioedema (AE) associated with angiotensin-converting enzyme inhibitors (A
CEi) is a rare, but potentially life-threatening adverse reaction. Several
studies have suggested that bradykinin (BK) is responsible for ACEi-induced
AE, but the mechanism remains unclear. We investigated the metabolism of B
K and des-Arg(9)-BK in the serum of 20 patients with a history of ACEi-asso
ciated AE and 21 control (C) subjects. Synthetic BK was incubated with the
sera for various periods of time and residual BK and generated des-Arg(9)-B
K were quantified by specific and sensitive enzyme immunoassays, No signifi
cant difference of half-life (t(1/2)) of both BK and des-Arg(9)-BK could be
measured between C subjects and patients with AE (AE) in absence of ACEi H
owever, an analysis according to the prolonged (+) or not (-) t(1/2) of des
-Arg(9)-BK allowed a new stratification of C subjects and AE patients in fo
ur subgroups. The preincubation of sera with enalaprilat at a concentration
inhibiting ACE significantly prevented the rapid degradation of BK and des
-Arg(9)-BK in these four subgroups. In presence of ACEi, a subgroup (50%) o
f AE patients (AE+) had a particularly significant rise of the t(1/2) of de
s-Arg(9)-BK. Once ACE was inhibited, the concentration or the nature of the
ACEi had no significant effect on the t(1/2) of des-Arg(9)-BK. However, a
test dilution of AE + sera with a control (C) serum showed that an enzyme d
efect rather than a circulating inhibitor could be responsible for the abno
rmal metabolism of des-Arg(9)-BK when ACE is inhibited. In conclusion, half
of the patients with ACEi-associated AE present in serum had an enzyme def
ect involved in the des-Arg(9)-BK metabolism leading to its accumulation. T
he B-1 agonist could be responsible, at least in part, for the local inflam
matory reaction associated with the AE. (C) 1999 Elsevier Science B.V. All
rights reserved.