Repressed miR-34a Expression Dictates the Cell Fate to Corneal Endothelium Failure

Proliferator-Activated Receptor Alpha Inhibits Abnormal Extracellular Matrix Accumulation and Maintains Energy Metabolism in Late-Onset Fuchs Endothelial Corneal Dystrophy

Purpose

Fuchs endothelial corneal dystrophy (FECD) is the most common corneal endothelial dystrophy and guttae are crucial in causing progressive loss of corneal endothelium. This study aimed to find a way to inhibit the formation of guttae in FECD.

Methods and Results

Mitochondria fatty acid β-oxidation (FAO) and tricarboxylic acid (TCA) cycle processes were negatively enriched in the FECD group according to gene set enrichment analysis in GSE171830. In vivo UV-A-induced late-onset FECD mouse model were established. After irradiation, aged proliferator-activated receptor alpha (PPARα-/-) mice manifested greater corneal opacity, cornea edema, and varied corneal endothelial cell morphology compared with wild-type mice. The total metabolites in cornea of aged PPARα-/- mice and wild-type mice were detected by mass spectrometry. Metabolites of the FAO pathway were decreased in corneas of PPARα-/- mice, coincident with enzymes of FAO decreased in GSE171830. The score for FAO energy metabolism was negatively related to that of the TGF-β pathway according to gene set variation analysis. The express of alpha smooth muscle actin (αSMA) and Col1a were increased in aged PPARα-/- mice and small interfering PPARα B4G12 cell lines. After irradiation, activation or overexpression of PPARα demonstrated reduced corneal endothelial damage and reversal of Descemet membrane thickening, along with downregulation of fibrosis-related genes such as αSMA and collagen type I alpha 1 (Col1a). In vitro experiments revealed that fenofibrate could reverse fibrosis and damage of cell-to-cell connections induced by TGF-β. Additionally, fenofibrate was found to alleviate mitochondrial damage in B4G12 and increase oxygen consumption rates after TGF-β treatment.

Conclusions

Overall, we suggested that the overexpression or activation of PPARα can inhibit FAO energy dysfunction of corneal endothelium and the abnormal extracellular matrix formation in Descemet's membrane, which is the primary pathology of FECD. Thus, PPARα may be a potential target for attenuating the progression of FECD.

Evolution of therapeutic strategy based on oxidant-antioxidant balance for fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) stands as the most prevalent primary corneal endothelial dystrophy worldwide, posing a significant risk to corneal homeostasis and clarity. Corneal endothelial cells exhibit susceptibility to oxidative stress, suggesting a nuanced relationship between oxidant-antioxidant imbalance and FECD pathogenesis, irrespective of FECD genotype. Given the constrained availability of corneal transplants, exploration into non-surgical interventions becomes crucial. This encompasses traditional antioxidants, small molecule compounds, biologics, and diverse non-drug therapies, such as gene-related therapy, hydrogen therapy and near infrared light therapy. This review concentrates on elucidating the mechanisms behind oxidant-antioxidant imbalance and the evolution of strategies to restore oxidant-antioxidant balance in FECD. It provides a comprehensive overview of both conventional and emerging therapeutic approaches, offering valuable insights for the advancement of non-surgical treatment modalities. The findings herein might establish a robust foundation for future research and the therapeutic strategy of FECD.

Twelve-year outcome of Rho-associated protein kinase inhibitor eye drop treatment for Fuchs endothelial corneal dystrophy: A case study

Purpose

To report the safety, efficacy, and long-term outcome in a case of Fuchs endothelial corneal dystrophy (FECD) treated by Rho-associated protein kinase (ROCK)-inhibitor eye drops in combination with removal of degenerated corneal endothelial cells (CECs) subsequent to transcorneal freezing.

Observations

A 52-year-old Japanese man diagnosed with early-stage FECD developed central corneal edema with decreased visual acuity (VA) in his left eye and was treated by ROCK inhibitor eye drops (Y-27632 10mM) q.i.d. for 1 week starting immediately subsequent to the removal of the damaged CECs via 2-mm-diameter transcorneal freezing in May 18, 2010. Before treatment, the best-corrected VA (BCVA) was 20/20 OD and 20/63 OS, and the central corneal thickness in the left eye was 643 μm and specular microscopy image at the central cornea was not detected due to edema. Corneal transparency recovered, and the BCVA improved to 20/20 within two weeks. At 12 years post treatment, the cornea in left eye remained transparent without corneal edema, and the CEC density at the central cornea was 1294 cells/mm² and the central corneal thickness was 581 μm. The annual decrease of CECs at the central cornea was 1.1%, and VA was maintained at 20/25. Multiple guttae were observed in the peripheral region, but few in the central region were removed by transcorneal freezing treatment, and relatively normal and healthy CECs were observed.

Conclusions and importance

The findings in this case suggest the potential long-term safety and efficacy of the medical therapy by ROCK-inhibitor eye drop for early-stage FECD.

The Interplay between Metabolites and MicroRNAs in Aqueous Humor to Coordinate Corneal Endothelium Integrity

Purpose

The purpose of the study was to clarify the interplay between metabolites and microRNAs (miRs) in the aqueous humor (AqH) of bullous keratopathy (BK) patients to retain human corneal endothelium (HCE) integrity.

Design

Prospective, comparative, observational study.

Participants

A total of 55 patients with BK and 31 patients with cataract (Cat) as control.

Methods

A biostatic analysis of miRs and metabolites in the AqH, hierarchical clustering, and a least absolute shrinkage and selection operator (Lasso) analysis were employed. The miR levels in AqH of BK (n = 18) and Cat (n = 8) patients were determined using 3D-Gene human miR chips. Hierarchical clusters of metabolites detected by liquid chromatography-mass spectrometry or gas chromatography-mass spectrometry in AqH specimens from 2 disease groups, BK (total n = 55) and Cat (total n = 31), were analyzed twice to confirm the reproducibility. The analytical procedure applied for investigating the association between metabolites and miRs in AqH was the exploratory data analysis of biostatistics to avoid any kind of prejudice. This research procedure includes a heat-map, cluster analysis, feature extraction techniques by principal component analysis, and a regression analysis method by Lasso. The cellular and released miR levels were validated using reverse transcription polymerase chain reaction and mitochondria membrane potential was assessed to determine the functional features of the released miRs.

Main Outcome Measures

Identification of interacting metabolites and miRs in AqH attenuating HCE degeneration.

Results

The metabolites that decreased in the AqH of BK patients revealed that 3-hydroxyisobutyric acid (HIB), 2-aminobutyric acid (AB) and branched-chain amino acids, and serine were categorized into the same cluster by hierarchical clustering of metabolites. The positive association of HIB with miR-34a-5p was confirmed (P = 0.018), and the Lasso analysis identified the interplay between miR-34a-5p and HIB, between miR-24-3p and AB, and between miR-34c-5p and serine (P = 0.041, 0.027, and 0.009, respectively). 3-hydroxyisobutyric acid upregulated the cellular miR-34a expression, mitochondrial membrane potential, and release of miR-184 in dedifferentiated cultured HCE cells.

Conclusions

Metabolites and miRs in AqH may synchronize in ensuring the integrity of the HCE to maintain efficient dehydration from the stroma.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Cellular Interplay Through Extracellular Vesicle miR-184 Alleviates Corneal Endothelium Degeneration

OBJECTIVE

The objective of the study was to reveal the presence of cellular interplay through extracellular vesicle (EV) microRNAs (miRs), to dampen the vicious cycle to degenerate human corneal endothelium (HCE) tissues.

DESIGN

Prospective, comparative, observational study.

METHODS

The miR levels in neonate-derived corneal tissues, in the aqueous humor (AqH) of bullous keratoplasty and cataract patients, as well as in the culture supernatant (CS) and EV of cultured human corneal endothelial cells (hCECs), were determined using 3D-Gene human miR chips and then validated using the real-time polymerase chain reaction. The extracellularly released miRs were profiled after the forced downregulation of cellular miR-34a, either by an miR-34a inhibitor or exposure to H₂O₂. The senescence-associated secretory phenotypes and mitochondrial membrane potential (MMP) were assessed to determine the functional features of the released miRs.

MAIN OUTCOME MEASURES

Identification of functional miRs attenuating HCE degeneration.

RESULTS

The miRs in AqH were classified into 2 groups: expression in 1 group was significantly reduced in neonate-derived tissues, whereas that in the other group remained almost constant, independent of aging. The miR-34a and -29 families were typical in the former group, whereas miR-184 and -24-3p were typical in the latter. Additionally, a larger amount of the latter miRs was detected in AqH compared with those of the former miRs. There was also a greater abundance of miR-184 and -24-3p in hCECs, EV, and CS in fully mature CD44^-/dull hCEC, leading to sufficient clinical tissue regenerative capacity in cell injection therapy. The repression of cellular miR-34a, either due to miR-34a inhibitors or exposure to oxidative stress, unexpectedly resulted in the elevated release of miR-184 and -24-3p. Secretions of VEGF, interleukin 6, monocyte chemotactic protein-1, and MMP were all repressed in both mature CD44^-/dull and degenerated CD44⁺⁺⁺ hCEC, transfected with an miR-184 mimic.

CONCLUSIONS

The elevated release of miR-184 into AqH may constitute cellular interplay that prevents the aggravation of HCE degeneration induced by oxidative stress, thereby sustaining tissue homeostasis in HCE.