<p>Differential miRNA Expression: Signature for Glaucoma in Pseudoexfoliation</p>

Abstract

To investigate the microRNA (miRNA) profile in patients with different stages of pseudoexfoliation (PXF). Methods: Peripheral blood of patients with PXF (naïve to medical therapy and with no systemic disease/drugs) with ocular hypertension (OHT) and pseudoexfoliation glaucoma (PXG) was evaluated in triplicate for miRNA profiling using polymerase chain reaction (PCR) arrays. Those identified in the discovery stage were validated with evaluation of serum transforming growth factor-β1 (TGF-β1) levels by ELISA. The downstream targets of TGF-β1 and unfolded protein response (UPR) were analyzed using reverse transcriptionquantitative polymerase chain reaction (RT-qPCR). Predicted targets of the identified miRNA and KEGG pathway analysis were done using miRbase and DIANA tools mirPathv3.1. Results: We found hsa-miR-122-5p, hsa-miR-124-3p and hsa-miR-424-5p to be upregulated in PXG targeting 3 specific pathways namely TGF-β1, fibrosis/ECM and proteoglycan metabolism with common effectors like SMAD/3/2. The unfolded protein response (UPR) genes were significantly downregulated in all stages of PXF suggesting this as the key mechanism for protein aggregates in PXF syndrome. Serum TGF-β1 was significantly upregulated as disease progressed to later stages in PXG. This elevation in advanced stages was associated with significantly differential expression of downstream pathways and fibrotic genes in OHT compared to PXG predominantly through the SMAD3, a canonical pathway marker. Conclusion: Circulatory miRNA differentially regulating TGF-β1 and downstream targets including UPR genes may be the key mechanisms for glaucoma onset in PXF.

TGFβ1, MMPs and cytokines profiles in ocular surface: Possible tear biomarkers for pseudoexfoliation

“…Concentration of TGFβ1 was evaluated in our previous study [ 20 ] and as expected these results are consistent with our previous results as we found in tears and AH, its expression is higher in PXG as compared to PXF or control. The MMP-9 and MMP-2 activities in serum were significantly upregulated in PXF and PXG compared to control while MMP-9 significantly downregulated in PXG when compared to PXF ( Fig 2d and 2e ).…”

“…The intensity of antibody immunostaining was scored as: 0 (none), 1 (weak), 2 (moderate), and 3 (strong). Total immunostaining scores, which combined intensity and distribution of immunostaining, were ranked as low (intensity 0–1 and distribution 0–4, or intensity 2 and distribution 0–1) or high (intensity 2–3 and distribution 2–4) [ 20 , 21 ].…”

Primary Human Trabecular Meshwork Model for Pseudoexfoliation

“…Lower concentration of 5 ng/mL showed asymmetric changes with different molecules getting upregulated at different time points suggesting the pro-fibrotic activity was maximally upregulated at 10 ng/mL of TGF-β1 after 24 h of sustained exposure. Since misfolded proteins seen in pseudoexfoliation recruits the Unfolded protein response (UPR) pathway and the inflammatory cytokines, we evaluated the expression of UPR genes X-box-binding protein 1 ( XBP1 ) and Chaperon containing TCP1 subunit 4 ( CCT4 ) that we found earlier to be downregulated in patients with advanced pseudoexfoliation glaucoma [ 15 ]. Consistent with our earlier study, we found XBP1 and CCT4 to be downregulated in vitro after 48 h exposure of 10 ng/mL TGF-β1 ( Figure 3 f).…”

“…We also found decreasing tear and aqueous MMP9 activity, with increased inflammatory cytokine levels, in severe PXG eyes compared to primary glaucoma [ 14 ], suggesting that the elevated TGF levels somehow were important for molecular events that causes the disease. We also found serum levels to parallel the levels in the aqueous and tears with several key miRNA driven by TGF-β1 to be upregulated in eyes with ocular hypertension (OHT) and PXG [ 15 ]. This was also associated with downregulation of several unfolded protein response (UPR) genes, a key mechanism of abnormal ECM homeostasis in PXF.…”

miRNAs and Genes Involved in the Interplay between Ocular Hypertension and Primary Open-Angle Glaucoma. Oxidative Stress, Inflammation, and Apoptosis Networks

“…Oxidative/nitrosative stress plays a pivotal role in POAG pathogenesis [ 12 , 15 , 39 ]; we may hypothesize that in the course of glaucoma, the pro-oxidants may induce the expression of miR-26b-5p, as reflected in this work [ 39 , 40 , 41 ]. Interestingly, hsa-miR-26b-5p has recently been involved in pseudoexfoliative glaucoma through interaction with the TGFR1 and TGR2 part of SMAD2 [ 42 ].…”