Abstract
Purpose:
We have observed that UVB corneal injuries heal faster than equivalent nitrogen mustard (NM)-induced wounds. Our overall goal is to elucidate what mechanisms that are involved in the delay of corneal wound healing after mustard injury.
Methods:
Rabbit corneal organ cultures were exposed to nitrogen mustard (NM) or UVB at doses that result in 60% epithelial-stromal separation at 24 hr post exposure. Corneal cultures were allowed to heal for 7 days, then were processed for H and E staining, immunofluorescence, and Western blot analysis .
Results:
UVB-exposed corneas reestablished epithelial-stromal integrity within 7 days of exposure, but equivalent corneal injury due to NM exposure was only partially healed by 7 days. In areas where the epithelial-stromal junction was reestablished in NM-exposed corneas, the number of fibroblasts residing in the anterior stroma after 7 days was greatly reduced, and repopulation lagged behind that of UVB-treated corneas. Local areas where the epithelial-stromal junction was imperfectly reformed were often observed in NM-exposed corneas, but not in UVB exposed corneas at 7 days post exposure. Immunofluorescence analysis of organ cultured corneas demonstrated that the expression of the furin was still elevated 7 days after NM exposure. Interestingly, ADAMTS4 was expressed in UVB-exposed corneas for 3 days after exposure, while in NM-exposed corneas ADAMTS4 persisted for 5 days after exposure. The expression level of the enzyme was about 5 times greater in NM-exposed than in UVB treated corneas.
Conclusions:
The difference in healing time of equivalent corneal injuries induced by NM-exposure versus UVB-exposure may be related to the extended activity of enzymes like furin and ADAMTS4.
Keywords: 482 cornea: epithelium •
765 wound healing •
519 extracellular matrix