Systemic sclerosis is a multisystem autoimmune disease characterized by vascular dysfunction, immune dysregulation, and progressive tissue fibrosis. Cardiopulmonary complications and peripheral vascular involvement are the principal causes of disability and mortality.

Extracellular vesicles (EVs) have emerged as key mediators of paracrine intercellular communication. Preclinical studies further suggest that EVs mediate long-range inter-organ communication through the circulation. However, the inability to directly track EV trafficking in vivo in humans has limited the understanding of their contribution to systemic inter-organ communication.

The investigators propose that systemic sclerosis provides a unique human model for investigating circulating EV-mediated inter-organ communication in a multisystem disease. The central hypothesis is that arteriovenous differences in the molecular and cellular characteristics of circulating EVs reflect their dynamic exchange between individual organs and the bloodstream, and that these differences are associated with disease severity. Comparison of EVs across the circulation, rather than relying exclusively on peripheral blood samples, enables a more direct assessment of organ-specific EV release and uptake.

Characterizing EV dynamics along the circulatory pathway has the potential to identify novel biomarkers and therapeutic targets for systemic sclerosis while providing fundamental insights into EV-mediated inter-organ communication in humans.