The Role of Limbal Epithelial Stem Cells in Regulating Corneal (Lymph)angiogenic Privilege and the Micromilieu of the Limbal Niche following UV Exposure

Figure 4

Schematic representation of the impact of UVA and UVB exposure on the limbal epithelial niche: while short-term UVB irradiated limbal fibroblasts downregulate their prolymphangiogenic cytokines, they are no longer able to support the limbal epithelial stem cell phenotype while also causing inflammation. This way, the niche is disrupted and the proinflammatory shift causes the invasion of neutrophils and macrophages promoting neovascularisation (a). On the other hand, short-term UVA also causes a downregulation of proinflammatory and macrophage-attracting cytokines by the cells of the limbal niche. This model put forward the key function of limbal epithelial cells and fibroblasts following short-term UV exposure by employing a defence machinery against proinflammatory and pro(lymph)angiogenic events (b). Schematic picture based on [81, 122].