039 Functional profile of circulating eosinophils in atopic dermatitis

Atopic dermatitis (AD) may be accompanied by an increase in blood eosinophil (Eos) levels. A role for Eos in the pathophysiology of this disease is therefore suspected but not yet elucidated and justifies the need to clarify their functional profile. We conducted a prospective monocentric study that assessed the Eos phenotype between patients with moderate to severe AD (aged over 18 who fulfilled with AD UK working party criteria and presented a moderate or severe form of AD defined by SCORAD score ≥ 25 and/or EASI score ≥ 7) and healthy subjects (aged over 18, without atopic comorbidities or immunomodulatory treatment). Patients were included between December 2020 and April 2021. We included 23 patients (mean age at 33 y-o) and 14 healthy control subjects (HCS). Mean SCORAD was at 56.9. DA patients had a mean blood Eos level of 322.7/mm3 (vs 130.2/mm3 in HCS, p<0.0001). Mean fluorescence intensity of surface expression of CD125 (p=0,04), CD63 (p=0.01), CRTH2 (p=0.0002) and CCR3 (p<0.0001) were lower on Eos in AD patients compared to HCS. Conversely, CD69 surface expression was increased in AD patients (p=0.006). This profile was consistent with a higher level of Eotaxin-2 (p=0,0003), IL-3 (p=0,02) and TARC (p<0,0001) in the serum of AD patients. IL-4, IL-13 and IL-5 serum levels tended to be significatively higher compared with HCS. The phenotypic profile of circulating Eos from AD patients is distinct from HCS, reinforcing the concept of “priming” profile of Eos which are being functionally programmed to act in a tissue. This specific profile of Eos in AD justifies a better understanding of the exact role of Eos in AD.