Therapeutic effect of MK2 inhibitor on experimental murine dry eye

Abstract

PURPOSE. To investigate the role of mitogen-activated protein kinase-activated protein kinase-2 (MK2) in ocular surface damage of dry eye. METHODS. MK2 inhibition was performed in mice subjected to desiccating stress (DS) by topical application of MK2 inhibitor (MK2i) or vehicle eye drops. The total and phosphorylated MK2 in conjunctiva were detected by Western blot. The phenol red cotton test was used to measure tear production, and Oregon green dextran staining was performed to assess corneal epithelial barrier function. PAS staining was used to quantify conjunctival goblet cells. Immunofluorescent staining and quantitative RT-PCR were used to assess the expression of matrix metalloproteinase (MMP)-3 and -9 in corneal epithelium. Apoptosis in ocular surface was assessed by TUNEL and immunofluorescent staining for activated caspase-3 and -8. Inflammation was evaluated by CD4+ T-cell infiltration and production of T helper (Th) cytokines, including IFN-γ, IL-13, and IL-17A in conjunctiva. RESULTS. DS promoted MK2 activation in conjunctiva. Compared with vehicle control mice, MK2i-treated mice showed increased tear production, decreased goblet cell loss, and improved corneal barrier function. Topical MK2 inhibition decreased the expression of MMP-3 and -9 in corneal epithelium, and suppressed cell apoptosis in ocular surface under DS. Topical MK2 inhibition decreased CD4+ T-cell infiltration, with decreased production of IFN-γ and IL-17A and increased production of IL-13 in conjunctiva. CONCLUSIONS. Topical MK2 inhibition effectively alleviated ocular surface damage via suppressing cell apoptosis and CD4+ T-cell-mediated inflammation in ocular surface of dry eye.