Characterization, biodistribution and functional Studies of immune-therapeutic Exosomes: implications for inflammatory lung diseases and COVID 19

Abstract

Abstract Dendritic cell (DC)-derived exosomes (DC EXO), natural nanoparticles of endosomal origin, are under intense scrutiny in clinical trials for various inflammatory diseases. DC EXO are well-tolerated by the host and can be custom-tailored for immunomodulatory functions. Previously we documented the efficacy of immunoregulatory DCs EXO (regDCs EXO) as immunotherapy for inflammatory bone disease in-vivo. However, the on- and off-target effects of these therapeutic regDC EXO and how target signaling in acceptor cells is activated is unclear. In the present report, therapeutic regDC EXO were analyzed by high throughput proteomics, with non-therapeutic EXO from immature DCs and mature DCs as controls, to identify shared and distinct proteins and potential off-target proteins. The predominant expression in regDC EXO of immunoregulatory proteins as well as proteins involved in trafficking from the circulation to peripheral tissues, prompted us to investigate how these EXO are biodistributed to major organs after intravenous injection. Live animal imaging showed preferential accumulation of regDCs EXO in the lungs. In addition, TGFB1 in regDCs EXO sustained downstream regulatory signaling in acceptor DCs. Blocking experiments suggested that sustaining TGFB1 signaling require initial interaction of regDCs EXO with TGFB1R followed by internalization of regDCs EXO with TGFB1-TGFB1R complex. Finally, these regDCs EXO that contain immunoregulatory cargo and showed biodistribution to lungs could downregulate the main SARS-CoV-2 target receptor, ACE2 on recipient lung parenchymal cells via TGFB1 in-vitro. In conclusion, these results may have important immunotherapeutic implications for lung inflammatory disorders and COVID19.