Molecular Determinants of Neutrophil Extracellular Vesicles That Drive Cartilage Regeneration in Inflammatory Arthritis.

Objective: This study was undertaken to establish the potential therapeutic profile of neutrophil-derived extracellular vesicles (EVs) in experimental inflammatory arthritis and associate pharmacological activity with specific EV components, focusing on microRNAs.

Methods: Neutrophil EVs were administered intra-articularly through a prophylactic or therapeutic protocol to male C57BL/6 mice undergoing serum-transfer-induced inflammatory arthritis. Transcriptomic analysis of knees was performed on joints following EV administration, naive and arthritic mice (untreated; n = 4/group) and EV-treated diseased mice (intra-articular administration) with contralateral (vehicle-treated; n = 8/group). Comparison of healthy donor and patients with rheumatoid arthritis (RA) neutrophil EVs was performed.

Results: EVs afforded cartilage protection with an increase in collagen-II and reduced collagen-X expression within the joint. To gain mechanistic insights, RNA sequencing of the arthritic joints was conducted. A total of 5,231 genes were differentially expressed (P < 0.05), with 257 unique to EV treatment. EVs affected key regenerative pathways involved in joint development, including Wnt and Notch signaling. This wealth of genomic alteration prompted to identify microRNAs in EVs, 10 of which are associated with RA. As a proof of concept, we focused on miR-455-3p, which was detected in both healthy donor and RA EVs. EV addition to chondrocyte cultures elevated miR-455-3p and exerted anticatabolic effects upon interleukin-1β stimulation; these effects were blocked by actinomycin or miR-455-3p antagomir.

Conclusion: Neutrophils from patients with RA yielded EVs with composition, efficacy, and miR-455-3p content similar to those of healthy volunteers, suggesting that neutrophil EVs could be developed as an autologous treatment to protect and repair joint tissue of patients affected by inflammatory arthritides.