Limbal stem cell dysfunction induced by severe dry eye via activation of p38 MAPK signaling pathway

Abstract

Purpose : To investigate the fate of limbal stem cells in severe dry eye and the underlining mechanism.

Methods : A severe aqueous tear deficiency dry eye (SDE) Sprague Dawley (SD) rat model was established by removing the extra orbital and infraorbital lacrimal glands. The tear production, slit lamp and corneal fluorescein staining was applied to assess the characteristic of ocular surface in the model. qRT-PCR and immunofluorescence was used to investigate the expression of markers about corneal epithelium differentiation, proliferation, stemness, inflammatory response and p38 signaling pathway activity. The stemness of limbal stem cells was verified by the limbal epithelium colony-forming efficiency (CFE). The p38 inhibitor (SB203580) was applied in vivo model and the in vitro dry eye model by normal rat limbal epithelium cultured in the hyperosmolar medium.

Results : One month after the operation, rat aqueous tear secretion dramatically reduced, blood vessels invaded into central cornea, inflammatory cells infiltrated into limbal stroma. K12 and Pax6 expression was dramatically reduced, while K10, Sprr1b and MUC5AC were upregulated in the corneal epithelium of the SDE rats. The proliferation of limbal epithelium was upregulated while stem/progenitor marker ABCG2 expression and the limbal epithelial colony-forming efficiency was decreased under SDE condition. Furthermore, the p38 MAPK signaling pathway was activated in the limbal corneal epithelium of SDE rats. The abnormal differentiation and stemness loss of cornea epithelium could be reversed by applying p38 inhibitor in vivo and in vitro SDE model.

Conclusions : Severe dry eye could lead to limbal stem cell dysfunction and the activation of p38 MAPK signaling pathway plays an essential role in this process.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.