Association of GSTO1, GSTO2, GSTP1, GPX1 and SOD2 polymorphism with primary open angle glaucoma

The causal effect of oxidative stress on the risk of glaucoma

Glaucoma is a complex multifactorial disease. Oxidative stress has been implicated in its pathogenesis. However, establishing a causal relationship between oxidative stress and glaucoma is challenging due to confounding and reverse causality. In this study, we performed bidirectional two-sample Mendelian randomization (MR) analyses based on genetic instrumental variables as proxies for 11 biomarkers of oxidative stress injury to investigate the causal relationship between oxidative stress and glaucoma. Eight significant associations were identified. Increased circulating levels of catalase (OR = 0.915, 95 % CI: 0.848-0.987, P = 0.022), retinol (OR = 0.481, 95 % CI: 0.248-0.932, P = 0.044) and superoxide dismutase (OR = 0.779, 95 % CI: 0. 616-0.986, P = 0.038) are associated with a decreased risk of glaucoma, whereas an increased myeloperoxidase level (OR = 2.145, 95 % CI: 1.119-4.111, P = 0.029) is associated with an increased risk of glaucoma. Glaucoma was causally associated with lower levels of total bilirubin (OR = 0.961, 95 % CI: 0.927-0.997, P = 0.039), glutathione peroxidase (OR = 0. 934, 95 % CI: 0.890-0.981, P = 0.006), paraoxonase (OR = 0.883, 95 % CI: 0.810-0.963, P = 0.005) and albumin (OR = 0.988, 95 % CI: 0.978-0.998, P = 0.014). The bidirectional MR analysis revealed a causal relationship between oxidative stress and glaucoma. These findings provide a greater understanding of the underlying mechanisms of glaucomatous neurodegeneration and imply a potential therapeutic approach for glaucoma through targeting oxidative stress pathways.

Analysis of Glaucoma Associated Genes in Response to Inflammation, an Examination of a Public Data Set Derived from Peripheral Blood from Patients with Hepatitis C

Introduction

Glaucoma is the second leading cause of blindness worldwide and despite its prevalence, there are still many unanswered questions related to its pathogenesis. There is evidence that oxidative stress and inflammation play a major role in disease progression. Glaucoma patients from several studies showed altered gene expression in leukocytes, revealing the possibility of using peripheral biomarkers to diagnose or stage glaucoma. The fact that glaucoma is associated with gene expression changes in tissues distant from the retina underscores the possible involvement of systemic oxidative stress and inflammation as potential contributing or compounding factors in glaucoma.

Methods

We assembled a list of oxidative stress and inflammatory markers related to glaucoma based on a review of the literature. In addition, we utilized publicly available data sets of gene expression values collected from peripheral blood mononuclear cells and macrophages from two patient groups: those chronically infected by the hepatitis C virus and those who have cleared it. Activation of the innate immune response can render cells or tissues more responsive to a second delayed proinflammatory stimulus. Additional gene expression data from these cells after subsequent polyinosinic:polycytidylic acid treatment, used to elicit an acute inflammatory response, allowed for the investigation of the acute inflammatory response in these groups. We used fold-change comparison values between the two patient groups to identify genes of interest.

Results

A comparison analysis identified 17 glaucoma biomarkers that were differentially expressed in response to HCV-mediated inflammation. Of these 17, six had significant p-values in the baseline vs treated values. Expression data of these genes were compared between patients who had cleared the Hepatitis C virus versus those who had not and identified three genes of interest for further study.

Discussion

These results support our hypothesis that inflammation secondary to Hepatitis C virus infection affects the expression of glaucoma biomarker genes related to the antioxidant response and inflammation. In addition, they provide several potential targets for further research into understanding the relationship between innate responses to viral infection and inflammatory aspects of glaucoma and for potential use as a predictive biomarker or pharmacological intervention in glaucoma.