D3.415 - Galectin-10 Expression in Plasma-Derived Extracellular Vesicles of Patients with Eosinophilic Esophagitis: a Pilot Study

Eosinophilic Esophagitis (EoE) is a chronic, T2/eosinophilic inflammatory disease caused by genetic, environmental factors along with epithelial barrier dysfunction. To date, EoE diagnosis and monitoring rely on eosinophil (Eos) count in biopsies of esophageal mucosa (EM). Therefore, there is a compelling need for alternative non-invasive markers for diagnosis and management of EoE. Previous studies identified in EM of EoE patients a subset of CD16⁺ Eos with impaired immune-suppressive function, partially mediated by the Eos-specific protein Galectin-10 (Gal-10), which was also released in EM through extracellular vesicles (EVs). Both EM CD16⁺ Eos and Gal-10⁺EVs correlated with response to therapy.

In this pilot study we isolated plasma EVs from patients with EoE, healthy and disease control subjects and investigated the expression of Gal-10, to evaluate if EM Gal-10⁺EVs is reflected in peripheral blood EVs and thus, it could potentially act as peripheral EoE biomarker. Informed consent was obtained from all subjects. Plasma samples (1mL) were processed for EV isolation by differential ultracentrifugation. Nanoparticles Tracking Analysis (NTA) was used to characterize EV concentration and size distribution; expression of specific EV markers, CD9 and CD63, and Gal-10 was obtained by Western blot (WB).

Along with clinical and EM Eos count, plasma EVs were isolated from EoE (n=4), eosinophilic non-GI diseases [atopic dermatitis (AD) n=2, hypereosinophilia (HE) n=1], non-eosinophilic GI disease [achalasia (AC) n=3] and healthy controls [(HC) (n=2)] individuals. EoE samples were evaluated pre-(T0) and post-(T1) treatments: food elimination diet (n=3) and topical budesonide (n=1). Treatment response (R)/non-response (NR) (n=2 each) was assessed by T1 EM Eos count.  NTA identified EV particles with a mode diameter (76,6-145,3nm) compatible with exosomes (<200nm). Plasma EV protein concentrations ranged from 27 to 165 μg/mL. WB analysis revealed expression of EV markers CD9 and CD63 in all samples; Gal-10 was undetectable in HC and AC EV samples but clearly expressed in EoE (3 out of 4) and eosinophilic diseases (AD, HE). In T1, EoE NR patients Gal-10 remained elevated while in one R patient EVs concentration and Gal-10 levels were reduced.

This pilot study reports the detection of Gal-10⁺EV in plasma of EoE patients. If confirmed in larger studies, Gal-10⁺EVs may reflect high EM Eos and may be evaluated as a non-invasive marker for EoE diagnosis and/or follow-up.