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29 EW GLAUCOMA June 2018 Contact information Liu: YUTLIU@augusta.edu the researchers used, counts how many copies of the miRNA are in the sample, which Dr. Liu said is more accurate than amplification. Overall, three miRNAs were significantly different in the POAG group compared to healthy controls, and five miRNAs in the exfoliation group were significantly different compared to controls. Drewry et al. found that none of the miRNAs identified were previously linked to glaucoma but noted miR-122-5p might target three glaucoma-asso- ciated genes. In addition, further analysis revealed that the miRNAs are involved in potential glaucoma pathways, Drewry et al. wrote. Dr. Liu said he, in collaboration with other researchers, is looking at miRNA from structures from donor eyes without glaucoma—Schlemm's canal endothelial cells, trabecular meshwork cells, the ciliary body, the iris, and cornea—in an effort to "build the whole profile of microR- NA along the anterior chamber to make correlations between different tissues with aqueous humor because aqueous humor has exchanges with every surrounding tissue. Any of these tissues can contribute to this pool, and then the microRNA in the aqueous humor can be engulfed by the neighboring tissue," Dr. Liu explained. The next step, he con- tinued, is to compare miRNA in the tissues of patients who have glau- coma to evaluate if expression has changed. "We are collaborating with other scientists right now to look at primary human-derived trabecular meshwork cells from a glaucoma state vs. normal to see what kind of microRNA expression changed and then look at what kind of messenger RNA (mRNA) changed with expres- sion because microRNA regulates expression of mRNA in a negative way. We plan to do a correlation of microRNA with their predicted targets in these glaucoma cells," Dr. Liu said. This research, Dr. Liu explained, could identify one of miRNA's specific targets related to cellular function. If one miRNA is found to affect cellular function of trabecular meshwork cells, for example, per- haps leading to a change in stiffness or contractibility because of its effect on a protein or enzyme, drugs could be targeted to that protein or enzyme to preserve tissue function. Dr. Liu also pointed out the potential of miRNA being used as a biomarker in serum testing for exfo- liation glaucoma, which he noted is a systemic disease. "It's an underdiagnosed dis- ease and if we have some systemic markers from human blood, I think it would provide more tools for screening and more awareness," he said. For this type of research to continue, Dr. Liu said it is important to obtain aqueous humor samples, which can only be collected at the time of cataract surgery with patient consent. "During cataract surgery, the aqueous humor will be drained out and other saline solution will replace it to maintain eye pressure … the aqueous humor will be wast- ed during surgery, but if we have a chance to get patients to agree to donate that part, that's great for the research," Dr. Liu said. "Without their contribution, this research would not be possible. All the re- sources were from my collaborators at Vanderbilt University and Duke University." EW Reference 1. Drewry MD, et al. Differentially expressed microRNAs in the aqueous humor of patients with exfoliation glaucoma or primary open-angle glaucoma. Hum Mol Genet. 2018;27:1263–1275. Editors' note: Dr. Liu has no financial interests related to his comments. " We plan to do a correlation of microRNA with their predicted targets in these glaucoma cells. " —Yutao Liu, PhD

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