Corneal alkali injury induces retinopathy via inflammation that is preventable with anti-TNF-α treatment

Abstract

Purpose : Ocular alkali burns can lead to blindness, even if promptly treated, due to cornea and retina damage. Our recent work ruled out the possibility of direct physical damage, as the cause of retinal injury. Instead, we found that upregulation of tumor necrosis factor alpha (TNF-α) causes blood-retinal barrier disruption and activation of retinal immune cells and retinal damage. We now explore the role of myeloid cells and retinal glial cells in retinal degeneration in alkali burns.

Methods : C57BL/6J, CX3CR1^+/eGFP and TNFRSF1A1B^-/- mice were used. Bone marrow chimerism was achieved by transferring CX3CR1^+/eGFP donor cells into busulfan-myelodepleted C57BL/6J mice. Corneal alkali burns were performed using a filter paper soaked with 1N NaOH, placed on cornea for 20 seconds, and then irrigated with saline for 15 minutes. Anti-TNF-α treatment (6.25mg/kg of infliximab intraperitoneally) was given promptly after irrigation. Mice were euthanized at 24 hours after the burn and the eyes were studied by quantitative PCR, flow cytometry, immunofluorescence and confocal microscopy.

Results : Cornea alkali burn induced significant corneal and retinal cell death at 24 hours and significant accumulation of CD45⁺CD11b⁺Ly6C⁺ immune cells in the iris (268-fold increase) of which 40% expressed MHC-II. This led to a marked upregulation of inflammatory cytokine genes, such as TNF-α (iris: 90-fold; retina: 50-fold) and IL-1β (iris: 190-fold; retina: 200-fold). Burns in the bone marrow chimera model showed that CX3CR1⁺ macrophages (3.64%±2.0% of CD45⁺ cells versus 0.58%±0.58% in controls) have crossed the blood-retinal barrier and entered into the retina. Subsequently this was associated with astrocyte and Müller glial cell activation, as indicated by GFAP upregulation (p<0.05) and further release of inflammatory mediators. Prompt anti-TNF-α treatment suppressed immune cell activation and CX3CR1⁺ cell infiltration, and led to retinal protection. The protective role of prompt anti-TNF-α therapy was further validated by using TNFRSF1A1B^-/- mice.

Conclusions : Corneal alkali burns cause significant retinal damage via cytokine upregulation and activation/infiltration of immune cells. Prompt inhibition of TNF-α by using monoclonal antibody inhibits monocyte infiltration and glial cell activation and protects the retina. Therefore, anti-TNF-α therapy may be a useful adjunct to standard emergency therapy after burns.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.