Profiles of matrix metalloproteinase activity in equine tear fluid during corneal healing in 10 horses with ulcerative keratitis.

The research article explores the fluctuating levels of matrix metalloproteinases (MMPs), enzymes involved in breaking down tissues, in the tears of horses with corneal ulcers. The study found an initial high level of MMPs, which significantly dropped as the ulcers healed, indicating the potential use of MMP levels as a method to monitor the healing process.

Research Objectives and Methodology

• The primary objective of this research work was to study the levels of matrix metalloproteinases (MMPs) in the tear fluids of horses diagnosed with ulcerative keratitis and understand their role in the process of corneal healing and stromal remodeling.
• Researchers gathered tear fluid samples from both eyes of ten horses with ulcerative keratitis on the day they were admitted to the hospital, as well as at various intervals until the full healing of the cornea.
• The activity of two specific MMPs (MMP2 and MMP9) was measured using a method called quantitative gelatin zymography.
• Horses in the study received medical treatment consisting of topical applications of equine serum, antibiotics, atropine, and systemic anti-inflammatory drugs. Additionally, surgical procedures were conducted on some horses alongside the medical treatment.

Results and Findings

• The findings revealed a significant initial high level of MMP activity in the tear fluids of the diseased eye compared to the healthy eye. This level significantly diminished as the corneal ulcers healed. Specifically, MMP activity in these ulcerated eyes decreased by 82.4% between the first day of admission and the day when the ulcer was fully healed.
• Further, once the cornea was entirely healed, the level of MMP activity was not significantly different from that found in the healthy eye. This indicates the successful treatment of corneal ulcers, as reflected by reduced enzyme activity in the tears.
• Interestingly, the study also documented a decrease in MMP activity in the contralateral (or healthy) eye, but this change was not found to be statistically significant.

Conclusions and Implications

• The study concluded that high levels of enzymatic activity in the tear film during the initial stages of corneal ulcers in horses decrease significantly as the ulcers heal. Hence, successful medical or surgical treatment is critical in reducing tear film proteolytic activity, which reflects the improvement in the clinical signs of corneal ulceration.
• The research suggests that measuring MMP activity in tear film might be a practical method to monitor the progression of corneal healing in horses suffering from ulcerative keratitis. This approach can provide potential insights into refining treatment strategies and diagnosing the stage of healing.