PURPOSE: Lifitegrast ophthalmic solution 5%, an LFA-1 antagonist, is indicated for treatment of dry eye disease (DED). This study assessed the mechanism of action of lifitegrast in a murine model of DED.

METHODS: DED was induced in 6-8-week-old mice by exposure to controlled environmental chamber and subcutaneous injections of scopolamine. Mice were treated with topical lifitegrast (or normal saline [NS]) TID. DED severity was assessed with corneal fluorescein score (CFS), and T cells were quantified by flow cytometry (FC) of corneal single-cell suspensions. In vitro T cell proliferation assay was performed using naïve T cells from draining lymph nodes (dLNs) and dendritic cells (DCs). Expression of chemokine receptors on dLNs T cells was assessed by RT-PCR and FC. In adoptive transfer experiments, T cells from DED mice treated with lifitegrast or NS were transferred to (1) NS-treated DED mice to assess limbal vascular sticking efficacy (adhesion) of CD4+ T cells (number of sticking/rolling cells) and (2) RAG knockout mice; DED severity and T cells (in corneas and dLNs) were assessed after 5 days.

RESULTS: CFS was significantly reduced and tear secretion was significantly improved after 15 days of lifitegrast versus NS treatment in DED mice (P<0.05). In vitro proliferation of T cells isolated from dLNs was 50% lower in the presence of lifitegrast versus NS (P<0.05), suggesting inhibition of T cell-DC synapse formation. Compared with NS treatment, lifitegrast treatment resulted in reduction of IFNγ-secreting CD4+ T cells (Th1) in the dLNs, recruitment of T cells to the cornea, and significant reductions in CXCR3 and CCR4 chemokine receptor expression by FC and CXCR3 mRNA levels in dLNs CD4+ T cells (P<0.05). The limbal vascular sticking efficacy of CD4+ T cells was significantly decreased following adoptive transfer of CD4+ T cells to NS-treated DED mice from lifitegrast-treated DED mice compared with transfer of CD4+ T cells from NS-treated DED mice after 15 days. Adoptively transferred CD4+ T cells from lifitegrast-treated versus NS-treated DED mice to RAG knockout mice resulted in significant reduction of CFS (P<0.05) and 60% reduction in CD4+ T cell recruitment into cornea, with no change in recruitment in dLNs.

CONCLUSIONS: These results demonstrate that topical lifitegrast has an effect beyond the ocular surface, directly on dLNs, through inhibition of T cell-DC synapse formation.