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. 2021 Apr;191(4):720–729. doi: 10.1016/j.ajpath.2021.01.003

Figure 1.

Figure 1

Pigment epithelium–derived factor (PEDF) enhances the suppressive phenotype of regulatory T cells in a murine model of dry eye disease (DED). Dendritic cells (DCs) are activated in response to the proinflammatory cytokines, released by corneal epithelium on exposure to desiccating stress, and migrate from the cornea to the draining lymph nodes (DLNs) to form the afferent arm of immunopathogenesis in DED. In the DLNs, DCs prime naïve T cells to generate proinflammatory cytokines secreting type 17 helper T (Th17) cells. The regulatory T cells (Tregs) are known to limit the interaction between DCs and naïve T cells, thereby preventing the generation of Th17 cells. However, in DED, Tregs are rendered dysfunctional, leading to loss of their immunosuppressive functions. This study shows a protective effect of recombinant PEDF (rPEDF) on Tregs in DED and subsequent amelioration of DED. CD86, cluster of differentiation 86; CTLA-4, cytotoxic T-lymphocyte–associated protein 4; FOXP3, forkhead box P3; GITR, glucocorticoid-induced TNFR-related protein; IFN-γ, interferon-γ; MHC, major histocompatibility complex; Th1, T helper cells type 1; TNF-α, tumor necrosis factor-α.