Nrf2 aqueous humor shows a higher concentration when GFAP is low in patients with diabetic cataracts versus those with senile cataracts

Abstract

Oxidative stress is involved in aging and ocular diseases, so it is necessary to evaluate the serum and aqueous humor concentrations of Nrf2 and GFAP as possible indicators of neuro-oxidative damage in patients with senile or diabetic cataracts. Observational, prospective, cross-sectional, and comparative study; we obtain serum and aqueous humor samples from patients with senile cataracts (reference group) or diabetic cataracts. Concentrations of Nrf2 and GFAP were determined by the ELISA technique, compared with the Student´s t-test, and correlated with Spearman´s Rho test. Eighty patients included, 36 with senile and 44 with diabetic cataracts. The glucose concentration was 40.75 mg/dL higher in the diabetic group (p < 0.001), as well as the proportion of systemic arterial hypertension (p = 0.02). Concentrations of Nrf2 and GFAP were only quantifiable in the aqueous humor samples, showing opposed values between the groups (Nrf2 was significantly superior in patients with diabetic cataracts, and GFAP higher in patients with age-related cataracts, without statistical difference); positive correlations were higher in when diabetic cataracts exist (r = 0.59). Our findings suggest an accentuated response of the Nrf2 pathway by the significant increase of this molecule in patients with diabetes and cataracts possibly to compensate for the ROS overexpression, meanwhile in patients with senile cataracts, GFAP has higher (but non-statistical) concentrations, maybe due to a lower Nrf2 modulation.