TNF-α Suppression Attenuates Limbal Stem Cell Damage in Ocular Injury.

Abstract

Ocular chemical injuries often cause uveal inflammation, upregulation of TNF-α at the limbus, and subsequent limbal stem cell (LSC) damage. In this study, we investigate the protective role of TNF-α suppression in LSC survival. Corneal alkali injuries were performed using NaOH as previously described by our group. Anterior chamber pH elevation in the absence of corneal alkali exposure was achieved by cannulation. A CX3CR1+/EGFP::CCR2+/RFP bone marrow chimera was used to study the role of innate immune cells in LSC damage, which was assessed by TUNEL assay, ABCB5, cytokeratin 12 and 13 staining, flow cytometry, in situ hybridization, and qPCR. Corneal neovascularization and conjunctivalization were evaluated by light microscopy. Intraperitoneal injection of 6.25 mg/kg infliximab was administered after irrigation. A TNFR1/2 knockout mouse was used to confirm the findings by a second method. Systemic administration of 6.25 mg/kg infliximab suppressed uveal inflammation after anterior chamber pH elevation or corneal alkali injury and led to reduction of TNF-α secreting CCR2+ and CX3CR1+ monocytes in the basal limbal tissue. In turn, this led to LSC survival (P < 0.01) and allowed reestablishment of K12+ epithelium (P < 0.05) on the injured cornea. Moreover, it led to less corneal neovascularization, conjunctivalization, and scarring, as compared with untreated animals. The protective effect of TNF-α suppression was confirmed in TNFR1/2 knockout mice. Prompt systemic administration of TNF-α inhibitor prevents LSC deficiency and facilitates corneal reepithelialization after alkali burn. TNF-α suppression may benefit the outcomes of other ocular injuries that cause LSC deficiency.