Abstract
Purpose:
To investigate the ocular fluid microRNA profiles of aqueous and vitreous and to explore the difference and similarities of microRNA species in normal vs. diabetic retinopathy patients as potential biomarkers.
Methods:
Blood, aqueous and vitreous samples were collected from 10 controls (macular pucker or macular hole patients) and 10 patients with diabetes undergoing vitreoretinal surgery. Samples were stored at -80oC. MicroRNAs were isolated using QIAgen microRNeasy kit, quantified on BioAnalyzer, labeled with FlashTag kit and profiled on Affymetrix GeneChip miRNA 2.0 microarrays. Data analysis was done using miRNAQCtool (Affymetrix) and IPA- Ingenuity Pathway Analysis software.
Results:
Our comparison of circulatory microRNA population of aqueous and vitreous humor showed that out of total of 847 miRNA probes on the Affymetrix GeneChip miRNA 2.0 we found 25 being common for both aqueous and vitreous samples, and an additional 11 being unique for aqueous, and 7 unique for vitreous. The most abundant common microRNAs are members of the families hsa miR-218, regulation of vascular patterning and vascular guidance cues , hsa-miR-193, differentiation of telocytes, stromal cells between blood vessels and neurons, with a role in intercellular signaling, and miR-let-7, regulation of retinal Muller glia dedifferentiation and retinal regeneration in teleosts . Our data suggests that there is a set of circulatory microRNAs which might have differential abundance in diabetic retinopathy patients compared to the control. Data suggests that TGF-beta pathway is the common target for microRNAs upregulated in aqueous and vitreous. We identified potential diabetic pre-retinopathy biomarker miR-20b, whose loss was established in plasma of diabetic patients, and it can be detected only in vitreous of diabetic pre-retinopathy patient, and not in diabetics with retinopathy. On the other hand, established diabetic plasma biomarker miR-126, which is also lost in diabetic patient’s plasma, is not present in aqueous or vitreous.
Conclusions:
The comparative profiling of circulatory microRNAs shows that these molecular species are present in aqueous and vitreous fluids. A small number of circulatory microRNAs have shown differential presence in normal vs. diabetic retinopathy, offering promise for further study on use of ocular fluids for further diagnostic or therapeutic purposes.
Keywords: 499 diabetic retinopathy •
427 aqueous •
533 gene/expression