Altered regulation of mRNA and miRNA expression in epithelial and stromal tissue of keratoconus corneas [miRNA]

Purpose: To evaluate conjunctival cell microRNA and mRNA expression in relation to observed phenotype and genotype of aniridia-associated keratopathy (AAK) in a cohort of subjects with congenital aniridia. Methods: Using impression cytology, bulbar conjunctival cells were sampled from 20 subjects with congenital aniridia and 20 age and sex-matched healthy control subjects. RNA was extracted and microRNA and mRNA analysis was performed using microarrays. Results were related to the presence and severity of AAK determined by a standardized clinical grading scale and to the genotype (PAX6 mutation?) determined by clinical genetics. Results: Of the 2549 microRNAs analyzed, 21 were differentially expressed relative to controls. Among these miR-204-5p, an inhibitor of corneal neovascularization, was downregulated 26.8-fold, while miR-5787 and miR-224-5p were upregulated 2.8 and 2.4-fold relative to controls, respectively. At the mRNA level, 539 transcripts were differentially expressed, among these FOSB and FOS were upregulated 17.5 and 9.7-fold respectively, and JUN by 2.9-fold, all components of the AP-1 transcription factor complex. Pathway analysis revealed dysregulation of several enriched pathways including PI3K-Akt, MAPK, and Ras signaling pathways in aniridia. For several microRNAs and transcripts, expression levels aligned with AAK severity, while in very mild cases with missense or non-PAX6 coding mutations, gene expression was only minimally altered. Conclusion: In aniridia, specific factors and pathways are strongly dysregulated in conjunctival cells, suggesting that the conjunctiva in aniridia is abnormally maintained in a pro-angiogenic and proliferative state, promoting the aggressivity of AAK in a mutation-dependent manner. Transcriptional profiling of conjunctival cells at the microRNA and mRNA levels presents a powerful, minimally-invasive means to assess the regulation of cell dysfunction at the ocular surface. MiRNA and mRNA expression profiles of epithelial and stromal cells from 8 patients with keratoconus compared to controls