The role and characterization of circulating microvesicles as early predictors of development of autoimmune rheumatic diseases

Autoimmune-mediated rheumatic diseases (ARD) encompass complex conditions often affecting young adults, representing a major cause of morbidity and disability. Early recognition of ARD would significantly improve patient prognosis while reducing the burden of health-related costs. To date, available biomarkers do not efficiently predict progression from very early stages to a definite ARD, thereby delaying a certain diagnosis. Growing evidence highlights a role for extracellular vesicles (EVs) in modulation of the immune response. EVs are small membrane-surrounded particles released by several cell types that shape the immune response via delivery of their specific content, mainly consisting of proteins and nucleic acids. Abnormalities in the EVs pool have been shown across several ARD which are not present in healthy individuals. Increased levels of circulating EVs which carry nuclear antigens and peculiar miRNA, or express Toll Like receptors and MHC-II molecules were suggested to promote inflammation in systemic lupus erythematosus, while other microRNA patterns were shown to associate with response or refractoriness to treatment in rheumatoid arthritis. However, whether EVs modifications substantially precede the onset of a full-blown ARD is not known.

Our aim is to investigate features of circulating EVs (number, size, surface markers and protein/RNA cargo) in a wide population of individuals with unspecific symptoms or immunological abnormalities suggestive for an impending ARD and to assess EVs capability to predict progression towards a definite ARD.

Subjects presenting with inflammatory arthralgias, skin rashes, fever of unknown origin, cytopenia and/or laboratory abnormalities will be recruited in three rheumatology Italian referral centers and followed-up with complete medical re-evaluation and blood sampling at regular timepoints or until development of a full-blown ARD.

The baseline and ongoing composition of the EVs pool will be analyzed and correlated with modifications in the clinical phenotype. The value of EVs patterns in predicting progression towards a definite ARD will be appropriately assessed and the feasibility of a composite predictive model integrating EVs information with available traditional biomarkers will be evaluated.

The process will be performed through the integration of diverse techniques including EVs isolation via size exclusion chromatography, analysis of protein and miRNA cargo through western blot and Next Generation Sequencing (NGS), respectively, evaluation of EVs direct immunomodulatory effect on resident cells through in vitro functional assays. The laboratory analysis will be followed by appropriate bioinformatics and statistical analysis, entailing the joint effort of clinicians and basic scientists.

At the end of our study, we expect to have gained a better understanding of the role of EVs in the development of ARD and to submit them as potential biomarkers in defining disease progression.