D1.346 - Immunology and epithelial barrier dysfunction in EGPA: the possible role of new biomarkers in stratifying disease risk and severity for precision medicine
Background
Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare systemic inflammatory disease involving blood vessels and resulting in different clinic phenotypes. Severe eosinophilic asthma (SEA), chronic rhinosinusitis with nasal polyps (CRSwNP) are associated with blood eosinophilia in the major part of EGPA patients. We aim to evaluate the demographics, biological and clinical features of EGPA patients to detect potential biomarkers useful to an early diagnosis, to assess the disease severity and evolution and to therapy response prediction.
Method
A total of 33 EGPA patients have been included. The patients’ demographic, biological and clinical characteristics have been analyzed. All the patients underwent pulmonary functional tests and electroneurography. Blood eosinophil count (BEC), eosinophilic cationic protein (ECP), antineutrophil cytoplasmic antibodies (pANCA and cANCA), total and specific anti-staphylococcal enterotoxins IgE (SE-IgE), serum free light chains (FLCs) k and λ have been measured as blood biomarkers.
Results
The mean age was 60.0 years, 48.5% of patients were male and 51.5% were female. 82.8% of patients were never smokers, 10.3% current smokers and 6.9% former smokers. SEA was present in 100% and CRSwNP in 88.5% of patients; 60.7% of patients presented peripheral neuropathy. The mean FEV1 was 74%.
All patients were treated with ICS/LABA, 29.6% with ICS/LABA/LAMA. ICS daily dose was high, medium or low in 32%, 60% and 8% of patients, respectively. OCS daily dose was >7.5 mg in 80.8% of patients. 48% were treated with biologics and 27% were treated with immunosuppressive drugs.
The mean BEC was 1950.0 cells/mm3. cANCA and pANCA were positive in 10.3% and 24.1% of patients, respectively. The mean value of ECP was 60.0 ug/L. 54.2% of patients presented SE-IgE. Serum FLCs k and λ were 21.1 and 15.7 mg/L, respectively; the mean FLC- k/FLC- λ ratio was 0.1.
A significant correlation between the OCS dose and and the serum level of FLCs λ has been observed (p=0.0085) Moreover, a correlation between the dose of OCS and the sensitization to SE was observed despite it was not statistically significant.
The value of FEV1 was significantly lower in cANCA positive patients (p=0.005664).
Conclusion
Our results confirm the limited power of ANCA as disease biomarkers in EGPA. The BEC should be associated with the dosage of serum ECP that could be used as an indicator of eosinophilic activity and tissue damage. The presence of SE-IgE could be considered as a marker of epithelial barrier damage in EGPA. The FLC-λ could be used as a marker of OCS exposure, OCS-linked damage and treatment response in EGPA patients.
