iNOS/NOX-mediated stress, telomerase activity, and hTERT expression as potential biomarkers in sleep apnea

Obstructive sleep apnea (OSA) is a sleep disorder caused by recurrent upper airway obstruction during sleep. This study aims to evaluate NADPH oxidase (NOX)/inducible nitric oxide synthase (iNOS)-mediated stress biomarkers in sleep apnea patients. In addition, human telomerase reverse transcriptase (hTERT) expression and telomerase activity were analyzed to elucidate the relationship between sleep apnea and cellular aging processes. The study included 47 OSA patients and 45 healthy control subjects. Telomerase enzyme activity and hTERT levels were measured to evaluate the relationship between OSA and cellular senescence mechanisms. Oxidative/nitrosative stress was analysed by measuring total oxidant/antioxidant status (TOS/TAS), oxidative stress index (OSI), NOX, total and native thiol, disulfide, iNOS, nitric oxide (NO), and 3-nitrotyrosine (3-NT). A significant increase in NOX, TOS, OSI, iNOS, 3-NT, NO, and a substantial decrease in SOD, TAS, total thiol, native thiol, and disulfide levels were found in the serum of OSA patients. A significant decrease was detected in both telomerase activity (p < 0.05) and hTERT levels (p < 0.001) in OSA patients, and the reduction in hTERT levels was statistically more pronounced. A positive correlation was found between the apnea-hypopnoea index and iNOS. hTERT level showed high discriminative performance in diagnosing OSA with an AUC value of 0.875. Decreased hTERT-mediated cellular responses and increased oxidative/nitrosative modifications at the macromolecular level are among the basic mechanisms of OSA pathogenesis.