Differential regulation of microRNA in ocular wound healing

Pterygium is a relatively common human ocular surface fibroproliferative disease that affects vision. Endogenously produced microRNA (miRNA) regulates gene expression in various ocular surface diseases and possibly pterygium. We aimed to investigate the role of miRNA in pterygium. Paired human pterygium and conjunctival tissues were obtained from patients diagnosed with primary pterygium. miRNA microarray profiling identified statistically significant miRNA changes which were matched to reciprocal significant changes in their target transcripts. We employed quantitative real-time polymerase chain reaction and found that hsa-miR-766 was up-regulated (2.57-fold) whilst hsa-miR-215 was down-regulated (0.49-fold) in pterygium compared to conjunctival control. Localization of miRNA was performed using in-situ hybridization. Transcript levels of predicted hsa-miR-766 targets, nuclear receptor subfamily 4, group A, member 1 and epidermal growth factor-containing fibulin-like extracellular matrix protein 1, were down-regulated in pterygium compared to conjunctiva by 0.53- and 0.64-fold, respectively. Collagens type 3, alpha 1 and type 4, alpha 2, both targets of hsa-miR-215, were up-regulated in pterygium by 3.01- and 3.11-fold, respectively. These changes were confirmed in the protein levels using immunofluorescent staining. Derangement of hsa-miR-766 and hsa-miR-215 may cause dysregulation of matrix rearrangement, cell proliferation and adhesion proteins, resulting in pterygium formation. Targeting miRNA may be a possible therapeutic approach in this disease. 3 pterygium samples and 3 matched conjuctiva samples from patients diagnosed with primary pterygium. A pool of all 6 samples was used as the common reference.