Treatment of Life-Threatening ACE-Inhibitor-Induced Angioedema

gC1qR Antibody Can Modulate Endothelial Cell Permeability in Angioedema

Angioedema is characterized by swelling of the skin or mucous membranes. Overproduction of the vasodilator bradykinin (BK) is an important contributor to the disease pathology, which causes rapid increase in vascular permeability. BK formation on endothelial cells results from high molecular weight kininogen (HK) interacting with gC1qR, the receptor for the globular heads of C1q, the first component of the classical pathway of complement. Endothelial cells are sensitive to blood-flow-induced shear stress and it has been shown that shear stress can modulate gC1qR expression. This study aimed to determine the following: (1) how BK or angioedema patients' (HAE) plasma affected endothelial cell permeability and gC1qR expression under shear stress, and (2) if monoclonal antibody (mAb) 74.5.2, which recognizes the HK binding site on gC1qR, had an inhibitory effect in HK binding to endothelial cells. Human dermal microvascular endothelial cells (HDMECs) grown on Transwell inserts were exposed to shear stress in the presence of HAE patients' plasma. Endothelial cell permeability was measured using FITC-conjugated bovine serum albumin. gC1qR expression and HK binding to endothelial cell surface was measured using solid-phase ELISA. Cell morphology was quantified using immunofluorescence microscopy. The results demonstrated that BK at 1 µg/mL, but not HAE patients' plasma and/or shear stress, caused significant increases in HDMEC permeability. The mAb 74.5.2 could effectively inhibit HK binding to recombinant gC1qR, and reduce HAE patients' plasma-induced HDMEC permeability change. These results suggested that monoclonal antibody to gC1qR, i.e., 74.5.2, could be potentially used as an effective therapeutic reagent to prevent angioedema.

Clinical Features and Disease Course of Primary Angioedema Patients in a Tertiary Care Hospital

Purpose

To give a better understanding of primary AE, the clinical characteristics and the possible therapeutic approaches.

Background

Angioedema (AE) is a non-pitting, non-itching swelling of skin or mucosa. The symptom can become life-threatening if located in the airways. Primary (monosymptomatic) AE is a manifestation of several different diseases and the diagnosis is not always straight-forward. The aetiological and pathophysiological factors of primary AE are not completely clarified. There is a need for further investigation.

Patients and Methods

This was a retrospective cohort study of patients referred to an outpatient dermatology clinic in a tertiary care hospital for clinical assessment due to primary AE in the period from 1996 to 2014.

Results

A total of 315 patients were identified with primary AE. The most frequent subtype was idiopathic AE (42.5%) and the second most common was angiotensin-converting enzymeinhibitor (ACEi)-induced AE (31.1%). Three patients were diagnosed with hereditary AE and one patient was diagnosed with acquired C1-inhibitor deficiency. At least 107 (34.0%) patients had established histaminergic AE. More than 1/3 of the patients were treated in an emergency room or hospitalized due to AE. A 98.1% of patients had experienced AE in the head and neck area. Seven patients were in the need of acute airway intervention. Six of these had ACEi-induced AE. Female sex and smoking were found to be risk factors for developing AE.

Conclusion

The most frequent diagnoses were histaminergic-, non-histaminergic idiopathic AE and ACEi-induced AE, whereas complement C1-inhibitor deficiency was rare. Histaminergic AE made up a substantial group of patients with primary AE. Even though there are different pathophysiological causes of AE, many cases have overlapping clinical manifestations, which make diagnosis and treatment difficult.