Anti-inflammatory actions of ripasudil ameliorate experimental autoimmune uveoretinitis in the acute phase.

Introduction: Rho-associated protein kinases (ROCKs) are a key regulator of T cell function, influencing a wide range of processes from activation to differentiation. Experimental autoimmune uveoretinitis (EAU) is an animal model of human non-infectious uveitis. This study aimed to evaluate the suppressive effects of ripasudil, a ROCK inhibitor, on ocular inflammation when administered from the onset of EAU and to elucidate the underlying mechanisms of its inhibitory effects.

Methods: EAU was induced in wild-type C57BL/6 mice by immunisation with IRBP peptide. Ripasudil or its vehicle, PBS, was intraperitoneally administered daily starting from 8 days post-immunisation. Clinical and histopathological examinations and analysis of T cell activation state were conducted. In addition, T cell gene expression profiles in the relevant immune functions were identified using single-cell RNA sequencing (scRNA-seq).

Results: The development of EAU was significantly attenuated and T cell activation and Th1 cell differentiation were significantly inhibited in mice with ripasudil (RIP-EAU) compared with mice with PBS (PBS-EAU), scRNA-seq using splenic T cells indicated that genes involved in the ROCK signalling pathway were highly expressed in low-differentiated Th1/Th17 cells, intermediate Th1 cells and differentiated Th1 cells. In addition, although differentiated Th1 and Th17 cells constituted similar proportions between PBS-EAU and RIP-EAU mice, RIP-EAU mice exhibited fewer low-differentiated Th1/Th17 cells and intermediate Th1 cells compared with PBS-EAU mice.

Conclusion: Ripasudil suppressed EAU when administered from the onset of the disease by inhibiting cells that strongly express genes involved in the ROCK signalling pathway and differentiate into Th1 cells.