Abstract
Purpose :
Both exfoliation glaucoma (XFG) and primary open-angle glaucoma (POAG) have been linked to decreased outflow of aqueous humor (AH). Our study aims to elucidate the factors involved by analyzing the microRNA (miRNA) expression profiles of AH samples from patients with POAG and XFG compared to non-glaucoma controls.
Methods :
Individual AH samples (50-100 µL) were collected from POAG and XFG patients and controls during surgical procedure. Total RNA was extracted using the Exiqon miRCURY RNA Isolation Kit and was characterized with the Agilent Bioanalyzer. miRNA expression was measured in 12 POAG samples, 12 XFG samples, and 11 controls using the NanoString Human v3 miRNA Expression Assay for 800 miRNAs. Data normalization and differential expression (DE) analysis were done using the nSolver 3.0 software and the limma Bioconductor package. miRTarBase, Ingenuity Pathway Analysis, and WebGestalt were used to analyze miRNA target interactions. The miRNA expression was validated using droplet digital PCR.
Results :
Overall, 205, 295, and 195 total miRNAs were identified in the POAG, XFG, and control samples, respectively. With a p-value ≤ 0.05 and an absolute log2 fold change ≥ 0.6, our DE analysis identified 3 miRNAs (miR-125b-5p, miR-302d-3p, and miR-451a) significantly different between POAG and controls, 5 miRNAs (miR-122-5p, miR-3144-3p, miR-320a, miR-320e, and miR-630) between XFG and controls, and 1 miRNA (miR-302d-3p) between POAG and XFG. While none of these miRNAs have been previously linked to glaucoma, miR-122-5p may target two known glaucoma genes: OPTN and TMCO1. Pathway analysis revealed that these miRNAs are also involved in potential glaucoma pathways, such as metabolism, cell death, and cell motility. Of the DE miRNAs, miR-125-5p and miR-320a are highly expressed in human ciliary body, cornea, and trabecular meshwork, whereas miR-451a has low expression in these tissues.
Conclusions :
Using the NanoString technology, we have successfully profiled the miRNA expression in human AH from patients with POAG and XFG and identified several POAG or XFG-associated miRNAs in AH, some of which may impact glaucoma-related genes and pathways. Further investigation into these miRNAs may help us better understand the pathogenesis of glaucoma subtypes and provide novel therapeutic targets.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.