All-trans Retinoic Acid Promotes Repair Of Corneal Epithelial Injury By Inhibiting Apoptosis And Promoting Tight Junction Remodeling

Objective All-trans retinoic acid(ATRA)is known to improve corneal epithelial defects.The effect of ATRA on apoptosis and remodeling of tight junction on corneal epithelial cell during the repair of corneal epithelial injury in rats was studied by using all-trans retinoic acid(ATRA)to treat the injured corneal epithelium.The possible mechanism is also discussed.Methods Normal male SD rats were divided into left and right eye groups,left eye as solvent control group and right eye as ATRA treatment group(medicated group).Three days after adaptive feeding,rats were anesthetized with 10% chloral hydrate.The ophthalmic surgical blade scraped the cornea and established a rat corneal epithelial damage repair model.Three days after adaptive feeding,rats were anesthetized with 10% chloral hydrate.The ophthalmic surgical blade scraped the cornea and established a rmodel of corneal epithelial injury repair in vivo.The effect of ATRA on wound closure was observed by measuring the wound area of the cornea with a digital camera.The apoptosis of the corneal tissue during the repair process was determined by TUNEL.The expression and distribution of apoptosis-related protein Bax in corneal epithelial tissues was determined by immunofluorescence assay(IF).The changes of corneal tissue permeability in the process of injury repair under different treatments was determined by permeability test.The expression of apoptosis-related proteins Bax,Bcl-2,procaspases-3,Caspases-3,procaspases-9,Caspases-9,mitogen-activated protein kinase(MAPK)signaling pathway protein,tight junction protein ZO-1,occludin and migration related proteins MLCK,p-MLC in corneal epithelial tissue after ATRA treatment were determined by Western blot.Results Successfully replicated corneal epithelial damage repair model.The rate of corneal injury repair in the 0.5 mmol/L ATRA drip treatment group was significantly higher than that in the control group,indicating that the repair of corneal epithelial damage was promoted by ATRA.The results of TUNEL showed that the apoptosis of corneal epithelial cells was decreased after ATRA treatment,which was less than that of CT group and blank group,indicated that ATRA could significantly reduce apoptosis of corneal epithelial cells.The results of IF showed that ATRA could decrease the expression of bax in corneal epithelium,and the results of tissue permeability experiment showed that ATRA could reduce corneal epithelial permeability during healing.ATRA effectively inhibited the expression of proapoptotic protein Bax(P<0.05),up-regulated the expression of apoptosis inhibitory protein bcl-2(P<0.05),which showed a certain anti-apoptotic effect.Meanwhile,the expression of Procaspases-9 and Procaspases-3 was up-regulated(P<0.05),and the expression of Caspases-3 and Caspases-9 were down-regulated(P<0.05).ATRA could also regulated the phosphorylation level of p38 ? ERK ? JNK in MAPK signaling pathway,whitch the phosphorylation level of p38 and ERK was down-regulated and the phosphorylation level of JNK was up-regulated.ATRA also up-regulated the expression of ZO-1,occludin protein in epithelial cells at a certain stage of injury,and down-regulated the expression of MLCK with inhibited the phosphorylation of MLC.