PURPOSE. Oxidative stress, characterized by an excessive production of reactive oxygen intermediates has been suggested to play a role in the pathogenesis of age-related macular degeneration (AMD). We examined the association of urinary F2-isoprostanes (F2-IsoPs), a marker of lipid peroxidation and the most reliable marker of oxidative damage with AMD.
METHODS.We included 238 adults with AMD and 390 age-and sex-matched controls without AMD who participated in a population-based cross-sectional study in Singapore (Singapore Chinese Eye Study, 2009-2011. AMD was graded from retinal photographs using the Wisconsin Age-Related Maculopathy Grading System. Urinary-free F2-IsoPs (pmol/mmol of creatinine) were measured by gas chromatography mass spectrometry (GC-MS). The association between F2-IsoPs and AMD was examined using unconditional logistic regression models adjusted for potential confounders including smoking, body mass index (BMI), blood pressure, total and high-density lipoprotein cholesterol, and history of cardiovascular disease.
RESULTS.Higher levels of F2-IsoPs were associated with AMD independent of potential confounders. Compared to quartile 1 (Q1) of F2-IsoPs, the multivariable odds ratio (95% confidence interval) of AMD in quartiles 2, 3, and 4 were 2.05 (1.26-3.32), 1.80 (1.10-2.94), and 1.76 (1.06-2.94), respectively. In subgroup analyses comparing Q4 to Q1, this association was stronger in women, those with BMI less than 25 kg/m 2 and those with hypertension, but no significant interaction was found (P interaction > 0.1 for each strata).CONCLUSIONS. Higher levels of urinary F2-IsoPs levels were associated with AMD independent of potential confounders in Chinese adults.Keywords: age-related macular degeneration, Asians, isoprostane, oxidative stress A ge-related macular degeneration (AMD) is a leading cause of irreversible blindness in older adults worldwide.1,2 Globally, 170 million adults have AMD, exerting a significant socioeconomic burden on healthcare systems.2,3 Despite significant research over decades, the pathogenesis of AMD is still not clear, and robust systemic biomarkers of AMD have not been identified yet. 4 Oxidative stress, characterized by an imbalance between excessive generation of reactive oxygen species (ROS) and their degradation by antioxidants, has recently been proposed to play a significant role in the pathogenesis of AMD. [5][6][7] With advancing age, the retina becomes more susceptible to oxidative stress and damage to the retinal pigment epithelium (RPE) occurs early in the natural history of AMD.8 At physiological concentrations, ROS are involved in cell signaling and regulation of immune responses. 9 However, disproportionate levels of ROS with concurrent impairment of enzymatic and nonenzymatic antioxidants damage cellular proteins, membrane lipids, and DNA that eventually lead to tissue injury, cellular death 10 resulting in accumulation of detrimental products including intracellular lipofuscin, and extracellular drusen.
6Oxidation of membrane lipids or lipid pero...