Abstract
Purpose :
Innate lymphoid cells (ILCs) are important mediators of mucosal inflammation and autoimmunity but have not been studied in association with intraocular disease. To test for a role of ILCs in uveitis, we used flow cytometry to quantify and characterize ILC populations in three mouse models.
Methods :
Experimental autoimmune uveitis (EAU), endotoxin-induced uveitis (EIU), and primed mycobacterial uveitis (PMU) were induced in C57BL/6J mice. Vitreous and retina were separated from the extra-retinal uveal tissues (choroid/iris/aqueous). ILCs were identified as CD45+, lineage -, CD127+, CD90.2+ mononuclear cells. Additional surface markers were used to identify ILC1s (NK1.1), ILC2s (ST2), and ILC3s (cKit). The impact of ILC deficiency on uveitis severity was tested in two forms of innate uveitis (EIU and acute PMU) using IL2rg-/- Rag2-/- mice which lack ILCs.
Results :
Naive retinas demonstrate no ILC1s or ILC2s and rare ILC3s (0.24% of CD45+ cells). In uveitis due to an innate stimulus (PAMPs), retinal ILC1s increased significantly during peak inflammation representing 1.46% of ocular CD45+ cells in EIU at 18h and 0.93% of CD45+ cells in PMU eyes 24h after uveitis induction. In contrast, at peak inflammation in EAU, the ILC1 population 0.70% of CD45+ is notably smaller than the ILC2 (7.07%, p = 0.001) and ILC3 (2.34%, p= 0.223) populations. A longitudinal analysis in the PMU model demonstrated that during the transition from an acute PAMP mediated uveitis to a chronic T cell mediated uveitis (day 7), ILC2s constitute 15.06% of CD45+ cells in the retina which is significantly more than ILC1s, 3.06% (p<0.0001) and ILC3s, 4.97% (p=0.0006). And these differences persist through at least day 21 with ILC2s constituting 10.31% of retinal CD45+ cells, ILC1s, 4.44% (p=0.0148) and ILC3s, 6.10% (p=0.4792). Acute uveitis clinical OCT scores were significantly decreased PMU and EIU in animals lacking ILCs.
Conclusions :
Our study is the first to identify the presence of ILCs in the retinas of animals with uveitis. Our data suggest that ILC1s are the first to respond to innate/PAMP initiated acute uveitis and are proinflammatory. In contrast, ILC2s and ILC3s enter the retina later in disease and only in association with adaptive immune responses. Further study will be required to determine the roles of ILC2s and ILC3s in the retina during uveitis.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.