Study of Urinary Protein Biomarkers in Hereditary Angioedema.

Background: Hereditary angioedema (HAE) is a rare and potentially life-threatening disease, and diagnosis is often missed or delayed. We aimed to identify noninvasive urinary protein biomarkers and to evaluate their potential roles in diagnosis and evaluation of disease severity.

Methods: Using data-independent acquisition (DIA)-based urinary proteomics, we identified proteins that were differentially expressed between patients with HAE and healthy control (HC) groups. Then, the parallel reaction monitoring (PRM)-targeted proteomics method was used to validate promising biomarker candidates in other HAE patients and HCs. Furthermore, enzyme-linked immunosorbent assay (ELISA) was conducted to verify levels of several key proteins in HAE, histamine-mediated angioedema, and HCs.

Results: Differential expression between HAE patients and HCs was observed in 269 of the 2562 urinary proteins identified. In the biofunction analysis, these differentially expressed proteins were significantly enriched in leukocyte migration, adhesion of immune cells, endothelial cell development, permeability of the vascular system, and death of immune cells. Moreover, a biomarker panel (C1 esterase inhibitor, pro-epidermal growth factor, and kininogen-1) was validated in 2 independent clinical cohorts with area under the curve values of 0.910 and 0.949 for a diagnosis of HAE. Additionally, the urinary clusterin level was found to be significantly correlated with HAE severity scores (R=-0.758, P<.01).

Conclusions: This study describes the first application of a DIA-PRM-ELISA workflow to identify noninvasive urine biomarkers of HAE. The results will contribute to our understanding of the pathogenesis of HAE and may also provide a potential alternative method for diagnosis and evaluation of disease severity.