Delivery of STAT3 through Extracellular Vesicles: basis of a new possible therapeutic approach for the treatment of Autosomal Dominant Hyper-IgE Syndrome (AD-HIES)

Autosomal Dominant Hyper-IgE syndrome (AD-HIES) is a rare primary immunodeficiency and multisystem disorder characterized by recurrent infections, complex somatic features and increased innate immune response. Dominant negative mutations in the signal transducer and activator of transcription 3 (STAT3) gene underlie most AD-HIES cases. Impairment of STAT3 functionality leads to compromised development of TH17 cells, a subset of CD4+ T cells responsible for host defence, resulting in the clinical features of AD-HIES. To date, no specific treatments are available, and the main therapeutic approaches are limited to supportive treatment and antimicrobial prophylaxis. Thus, the development of new therapeutic strategies represents an urgent need. Here we proposed the restoration of STAT3 signalling by Extracellular Vesicles (EVs)-mediated administration of fully functional wild type STAT3. A novel recombinant fusion construct of STAT3 tagged with EGFP was produced using a baculovirus-based expression system and characterized from a biochemical and biophysical point of view. EGFP-STAT3 was encapsulated in EVs isolated from B-lymphoblastoid cells conditioned medium using a saponin-assisted method. The obtained EVs were characterized by fluorescence detection, western blotting, and Nanoparticle Tracking Analysis. In addition, the internalization of EGFP-STAT3 was demonstrated by proteolysis reaction. The EVs delivery potential of EGFP-STAT3 was successfully assessed in an in vitro cellular model using confocal microscopy. The obtained results constitute the scientific background for further development of a new possible therapeutic approach for the treatment of AD-HIES.