Determination of Oxidative Stress Markers in the Aqueous Humor and Corneal Tissues of Patients With Congenital Hereditary Endothelial Dystrophy

Abstract

Purpose: The aim of this study is to determine the presence of oxidative stress markers in the aqueous humor (AH) and corneal tissues of patients with congenital hereditary endothelial dystrophy (CHED). Methods: Interventional prospective study was undertaken to quantify levels of ascorbic acid and glutathione in the AH of patients with CHED. AH was collected from patients undergoing keratoplasty and levels of ascorbic acid and glutathione were determined using biochemical assays and measured spectrophotometrically. AH collected from pediatric patients with cataract were used as control. Corneal sections of patients who underwent penetrating keratoplasty were obtained, and presence of glutathione peroxidase 1, catalase, and superoxide dismutase was determined by immunohistochemistry. Tissue sections obtained from cadaveric corneas unsuitable for clinical transplant were used as control. Results: Significantly increased ascorbic acid levels were determined in patients with CHED (605.6 ± 158.9 μM) compared with those in controls (190.5 ± 74.72 μM). However, a trend toward reduced level of glutathione was detected in patients with CHED compared with that in the controls. Increased glutathione peroxidase 1 staining and reduced expression of catalase was detected in corneal tissues of patients with CHED compared with those in control corneal tissues. There was no apparent changes observed in the expression of superoxide dismutase in the corneal sections obtained from patients with CHED. Conclusions: To the best of our knowledge, this is the first study to determine the levels of ascorbic acid and glutathione in AH of patients with CHED. Our data suggest the presence of oxidative stress in CHED that might be responsible for the pathological changes in patients with CHED.

Corneal Edema in Inducible Slc4a11 Knockout Is Initiated by Mitochondrial Superoxide Induced Src Kinase Activation

“…Oxidative stress is the main contributor to the pathophysiological process of FECD and CHED [25][26][27]. In the Slc4a11 KO, the lack of NH 3 -activated mitochondrial uncoupling hyperpolarizes the mitochondrial membrane potential, leading to excessive superoxide production [3].…”

Investigation of the functional impact of CHED- and FECD4-associated SLC4A11 mutations in human corneal endothelial cells

“…Characterized as an electrogenic membrane transporter that functions as either an ammonia (NH 3 )-sensitive H + transporter or NH 3 :H + co-transporter, SLC4A11 exhibits enhanced inward H + flux when perfused with NH 4 Cl [31,32]. While still currently debated, SLC4A11 is hypothesized to have multiple roles in CEnC [33], which include: playing a role in transmembrane water flux; [34] facilitating glutamine catabolism to reduce ammonia-related oxidative stress in CEnC; [35][36][37] functioning as an ammonium-activated mitochondrial uncoupler to prevent mitochondrial membrane potential hyperpolarization and reduce superoxide production; [38] promoting endothelial pump activity by facilitating lactate:H+ flux across the corneal endothelium to maintain corneal clarity; [39,40] aiding in cell adhesion to the Descemet membrane via its extracellular loops; [41] and functioning as an NRF2-activated oxidative stress response protein via NRF2-binding sites within the SLC4A11 promoter [42][43][44].…”