Rexinoid NEt-3IB Promotes Resident Macrophage Gene Expression and Mitigates Desiccation-Induced Ocular Surface Disease

Purpose: To evaluate the effects of rexinoid NEt-3IB on desiccating stress-induced dry eye, as well as monocyte/macrophage gene expression and cellular trajectory. Methods: Eyes were topically treated with rexinoid NEt-3IB (5 µM) or vehicle three times a day for 5 days of desiccating stress-induced dry eye. Single-cell RNA sequencing (RNA-seq) profiled gene expression in conjunctival immune cells. RNA-seq was also used to evaluate gene expression in lipopolysaccharide (LPS)-stimulated, dexamethasone-treated (Dex, 1 µM), or NEt-3IB-treated (1-1000 nM) cultured monocytes. Cellular state trajectory and latent time were inferred with scVelo, and latent-time-associated genes were identified using Monocle 3. Permeability to Oregon Green-labeled dextran was used to assess corneal barrier, and conjunctival goblet cell parameters were measured in periodic acid-Schiff (PAS)-stained wholemounts. Results: NEt-3IB significantly stimulated homeostatic, phagocytotic, and anti-inflammatory gene expression and suppressed inflammatory gene signatures in conjunctival monocyte/macrophage cells compared to vehicle (Padj < 0.05). Latent time trajectory analysis and flow cytometry further revealed that NEt-3IB preserved resident macrophage-associated gene and protein expression. Compared to vehicle, corneal labeled dextran uptake was lower (P = 0.001) and conjunctival goblet cell total (P = 0.001) and single-cell (P = 0.01) areas were higher in the NEt-3IB group. The impact of NEt-3IB on differentially expressed genes in cultured monocytes mirrored its effects in vivo. NEt-3IB and dexamethasone suppressed inflammatory mediator expression; however, NEt-3IB enhanced the expression of homeostatic factors, including Igf1 and Il10. Conclusions: Rexinoid NEt-3IB suppresses inflammatory and stimulates homeostatic gene expression in the monocyte/macrophage lineage and desiccation-induced ocular surface disease. Rexinoid therapy may prove to be a novel approach to treat dry eye by stimulating endogenous production of homeostatic/anti-inflammatory factors.