Targeted Delivery of Avacopan via Sortase A-Modified Extracellular Vesicles Attenuates Endotoxin-Induced Retinal Inflammation

Uveitis is a prevalent ocular inflammatory condition and a major contributor to global vision impairment. The inflammatory cascade activates the Complement System, resulting in the production of C5a, which interacts with its receptor C5aR1 on microglia, promoting excessive neutrophil recruitment and Reactive Oxygen Species (ROS) bursts. In this study, we develop a targeted drug delivery system by conjugating small extracellular vesicles with the microglia-binding peptide MG1 using Sortase A. The C5aR1 antagonist Avacopan was loaded into the modified EVs via extrusion. Using a lipopolysaccharide (LPS)-induced endotoxin-induced uveitis (EIU) model, we evaluate the effects of MG1-EVs/Ava on ocular inflammatory pathology, microglial migration, and retinal cytokine expression. In vitro assays are performed to assess the cytotoxicity of Avacopan as well as its impact on ROS generation and pro-inflammatory cytokine production. In addition, data-independent acquisition (DIA) proteomics analysis is conducted to explore the downstream signaling pathways involved in MG1-EVs/Ava-mediated therapeutic effects. In rescue experiments, siRNA-mediated knockdown of MAPK9 reverses the downregulation of C5aR1 and pro-inflammatory cytokines, further supporting its role in mediating the therapeutic effects of MG1-EVs/Ava. The findings of this study demonstrate both the therapeutic efficacy and mechanistic basis of MG1-EVs/Ava, highlighting its potential as a promising treatment strategy for infectious uveitis.

complement; drug delivery; exosomes; extracellular vesicles; inflammation; microglia; uveitis.