Intraocular immune response in human uveitis: time to look beyond animal models.

PURPOSE: To review the current and future approaches to investigating the intraocular immune response in human uveitis.

DESIGN: Perspective METHODS: Review of currently available methods for investigating the immune response in ocular tissues and fluids in patients with intraocular inflammation/ uveitis. The advantages and disadvantages of human studies have been compared to those of animal models of uveitis.

RESULTS: Animal models, while being excellent tools for mechanistic studies, do not replicate the clinical and immunological heterogeneity of human uveitis. Opportunities for immunological studies in human uveitis are mostly limited to histological studies, or sampling of intraocular fluids and peripheral blood. Histopathological studies can be enhanced by revisiting published historical data, tissue repositories or autopsy specimens. Intraocular fluids can be investigated by a variety of techniques. Among these, flow cytometry and single cell RNA sequencing (scRNAseq) provide single cell resolution. While the current technology is costly and labor-intensive, scRNAseq is less limited by the low cellular yield from intraocular fluids and allows unbiased immune profiling enabling discovery of new cellular subsets. Immunological phenotypes uncovered from human data can be further investigated in animal studies.

CONCLUSION: The diversity of the intraocular immune response in uveitis patients remains challenging but can be studied by multiple techniques including histopathology, flow cytometry and scRNAseq. Human data can be combined with animal studies for translating uveitis research into novel therapies.