Robust ocular inflammatory response to an immune allergic eye disease challenge in a novel murine IKZF1 transgenic model associated with Steven’s Johnson’s Syndrome.

Abstract

Purpose : To characterize the ocular phenotype of a novel transgenic mouse strain with a constitutional ocular expression of the IKZF1 isoform, found in humans to be associated with Steven’s-Johnson’s syndrome (SJS), after immune challenge using the allergic eye disease (AED) model.

Methods : IKZF1 transgenic mice (IK-Tg) were provided by Ueta et al. Experiments were carried out on wild-type (WT) Balb/c and IK-Tg mice aged 8-10 weeks. Both strains underwent immunization followed by a sequential topical challenge using an established model of AED. Clinical eye disease was assessed using (1) an established composite score (2) Meibomian gland plugging, and (3) fluorescein corneal photographs. The challenge-response of each group was compared by calculating the endpoint to baseline change in each score (Δ). Mann-Whitney test was used with a p<0.05 cutoff. Molecularly, flow cytometry was used to quantify conjunctival immune cell and submandibular lymph nodes (SMLN) cytokine expression. Fold-increase from unchallenged counterparts was calculated and results of the challenged groups were analyzed descriptively.

Results : After AED challenge, IK-Tg eyes had a significantly larger increase in composite ocular score (Δ ocular score: 5.6 [5.1,6.25] vs 4.8 [4.3,5.25], p=0.001) and Meibomian gland plugging (Δ plugs: 7 [4.25,9] vs 5 [4,6], p=0.01) plus a trend towards higher increase in corneal staining (Δ fluorescein staining: 3.5 [2.25,5] vs 1 [1,3], p=0.06) compared to challenged WT eyes [n=22/group] (Figure 1). In addition, challenged IK-Tg mice had a higher increase in % eosinophilic composition (5.1 vs 4.3-fold increase) and a higher overall % composition of neutrophils (11% vs 2%) in the conjunctival CD45 population compared to challenged WT mice [n=10/group]. Compared to their unchallenged counterparts, both groups experienced increased CD4 cytokine expression in the SMLNs with IK-Tg having a larger increase in IFN-gamma (1.5 vs 1.1 folds), a lower increase in IL-13 (1.9 vs 2.3 folds), and a similar increase in IL-17 (2.8 vs 2.9 folds) % expression change [n=10/group].

Conclusions : IK-Tg mice are characterized by a unique disease phenotype responding distinctly to immune challenge resulting in added exaggeration of ocular disease which can model the hypersensitivity of ocular inflammatory disorders, more specifically, SJS.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.