TY  - JOUR
N1  - © 2023 Esposito, Kontra, Giacomassi, Manou-Stathopoulou, Brown, Stratton, Verykokou, Buccafusca, Stevens, Nissim, Lewis and Pfeffer. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
TI  - Identification of autoantigens and their potential post-translational modification in EGPA and severe eosinophilic asthma
EP  - 14
Y1  - 2023/06/02/
AV  - public
VL  - 14
JF  - Frontiers in Immunology
KW  - Eosinophil
KW  -  autoantibodies
KW  -  autoantigens
KW  -  oxidative modification
KW  -  diagnostic test
KW  -  TREM1
KW  -  eosinophil peroxidase
KW  -  NETosis
A1  - Esposito, Ilaria
A1  - Kontra, Ioanna
A1  - Giacomassi, Chiara
A1  - Manou-Stathopoulou, Sotiria
A1  - Brown, James
A1  - Stratton, Richard
A1  - Verykokou, Galateia
A1  - Buccafusca, Roberto
A1  - Stevens, Michael
A1  - Nissim, Ahuva
A1  - Lewis, Myles J
A1  - Pfeffer, Paul E
ID  - discovery10184013
N2  - BACKGROUND: 
The chronic airway inflammation in severe eosinophilic asthma (SEA) suggests potential autoimmune aetiology with unidentified autoantibodies analogous to myeloperoxidase (MPO) in ANCA-positive EGPA (eosinophilic granulomatosis with polyangiitis). Previous research has shown that oxidative post-translational modification (oxPTM) of proteins is an important mechanism by which autoantibody responses may escape immune tolerance. Autoantibodies to oxPTM autoantigens in SEA have not previously been studied.


METHODS: 
Patients with EGPA and SEA were recruited as well as healthy control participants. Autoantigen agnostic approach: Participant serum was incubated with slides of unstimulated and PMA-stimulated neutrophils and eosinophils, and autoantibodies to granulocytes were identified by immunofluorescence with anti-human IgG FITC antibody. Target autoantigen approach: Candidate proteins were identified from previous literature and FANTOM5 gene set analysis for eosinophil expressed proteins. Serum IgG autoantibodies to these proteins, in native and oxPTM form, were detected by indirect ELISA.


RESULTS: 
Immunofluorescence studies showed that serum from patients with known ANCA stained for IgG against neutrophils as expected. In addition, serum from 9 of 17 tested SEA patients stained for IgG to PMA-stimulated neutrophils undergoing NETosis. Immunofluorescent staining of eosinophil slides was evident with serum from all participants (healthy and with eosinophilic disease) with diffuse cytoplasmic staining except for one SEA individual in whom subtle nuclear staining was evident. FANTOM5 gene set analysis identified TREM1 (triggering receptor expressed on myeloid cells 1) and IL-1 receptor 2 (IL1R2) as eosinophil-specific targets to test for autoantibody responses in addition to MPO, eosinophil peroxidase (EPX), and Collagen-V identified from previous literature. Indirect ELISAs found high concentrations of serum autoantibodies to Collagen-V, MPO, and TREM1 in a higher proportion of SEA patients than healthy controls. High concentrations of serum autoantibodies to EPX were evident in serum from both healthy and SEA participants. The proportion of patients with positive autoantibody ELISAs was not increased when examining oxPTM compared to native proteins.


DISCUSSION: 
Although none of the target proteins studied showed high sensitivity for SEA, the high proportion of patients positive for at least one serum autoantibody shows the potential of more research on autoantibody serology to improve diagnostic testing for severe asthma.

CLINICAL TRIAL REGISTRATION:  
ClinicalTrials.gov, identifier, NCT04671446.
SN  - 1664-3224
UR  - https://doi.org/10.3389/fimmu.2023.1164941
PB  - FRONTIERS MEDIA SA
ER  -