The Relationship Among Oxidative and Anti-Oxidative Parameters and Myeloperoxidase in Subjects With Obstructive Sleep Apnea Syndrome

Role of Oxidative Stress in the Occurrence and Development of Cognitive Dysfunction in Patients with Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea syndrome (OSAS) causes recurrent apnea and intermittent hypoxia at night, leading to several complications such as cognitive dysfunction. However, the molecular mechanisms underlying cognitive dysfunction in OSAS are unclear, and oxidative stress mediated by intermittent hypoxia is an important mechanism. In addition, the improvement of cognitive dysfunction in patients with OSAS varies by different treatment regimens; among them, continuous positive airway pressure therapy (CPAP) is mostly recognized for improving cognitive dysfunction. In this review, we discuss the potential mechanisms of oxidative stress in OSAS, the common factors of affecting oxidative stress and the Links between oxidative stress and inflammation in OSAS, focusing on the potential links between oxidative stress and cognitive dysfunction in OSAS and the potential therapies for neurocognitive dysfunction in patients with OSAS mediated by oxidative stress. Therefore, further analysis on the relationship between oxidative stress and cognitive dysfunction in patients with OSAS will help to clarify the etiology and discover new treatment options, which will be of great significance for early clinical intervention.

The effects of disease severity and comorbidity on oxidative stress biomarkers in obstructive sleep apnea

PURPOSE

Ischemia-modified albumin (IMA), total oxidant status (TOS), and total antioxidant status (TAS) are biomarkers used to evaluate oxidative stress status in various diseases including obstructive sleep apnea (OSA). In this study, we investigated the effects of disease severity and comorbidity on IMA, TOS and TAS levels in OSA.

METHODS

Patients with severe OSA (no-comorbidity, one comorbidity, and multiple comorbidities) and mild-moderate OSA (no-comorbidity, one and multiple comorbidities), and healthy controls were included in the study. Polysomnography was applied to all cases and blood samples were taken from each participant at the same time of day. ELISA was used to measure IMA levels in serum samples and colorimetric commercial kits were used to perform TOS and TAS analyses. In addition, routine biochemical analyses were performed on all serum samples.

RESULTS

A total of 74 patients and 14 healthy controls were enrolled. There was no statistically significant difference between the disease groups according to gender, smoking status, age, body mass index (BMI), HDL, T3, T4, TSH, and B12 (p > 0.05). As the severity of OSA and comorbidities increased, IMA, TOS, apnea-hypopnea index (AHI), desaturation index (T90), cholesterol, LDL, triglyceride, AST, and CRP values increased significantly (p < 0.05). On the other hand, TAS, minimum desaturation, and mean desaturation values decreased significantly (p < 0.05).

CONCLUSIONS

We concluded that IMA, TOS, and TAS levels may indicate OSA-related oxidative stress, but as the severity of OSA increases and with the presence of comorbidity, IMA and TOS levels may increase and TAS levels decrease. These findings suggest that disease severity and presence/absence of comorbidity should be considered in studies on OSA.

Causal relationship between levels of myeloperoxidase and obstructive sleep apnea: a bidirectional two-sample Mendelian randomization study

Background

Several observational studies have investigated the association between myeloperoxidase (MPO) and obstructive sleep apnea (OSA). However, the nature of this relationship remains uncertain due to potential selection and confounding biases. To resolve this, we conducted a bidirectional two-sample Mendelian randomization (MR) study to scrutinize the causal relationship between MPO and OSA.

Methods

Instrumental variables (IVs) for OSA were sourced from the publicly available FinnGen dataset, encompassing 38,998 OSA cases and 336,659 controls. Data on MPO were sourced from a study of 21,758 individuals conducted by the European Bioinformatics Institute (EBI). The primary MR analysis utilized the inverse-variance weighted (IVW) method, with MR-Egger intercept and leave-one-out methods assessing pleiotropy and Cochran's Q test determining heterogeneity.

Results

The IVW analysis indicated a causal relationship between heightened MPO levels and an increased incidence of OSA. Individuals with elevated MPO levels manifested a higher propensity to develop OSA, exhibiting an odds ratio (OR) of 1.075 and a 95% confidence interval (CI) of 1.011-1.143 (p = 0.021). Conversely, the reciprocal analysis unveiled no significant association between OSA and heightened MPO levels (p = 0.643). No directional pleiotropy was identified through the MR-Egger intercept test (p > 0.05).

Conclusion

Our study provides evidence of an association between elevated MPO levels and an increased incidence of OSA. However, OSA does not necessarily lead to elevated MPO levels. When patients present with high MPO levels, screening for OSA may be advisable, considering their clinical characteristics.

Current Smoking Determines the Levels of Circulating MPO and MMP-9 in Adults with Coronary Artery Disease and Obstructive Sleep Apnea

(1) Background: Obstructive sleep apnea (OSA) is common in patients with coronary artery disease (CAD), in which a rupture of atherosclerotic plaques and oxidative stress play a role in the initiation and progression of the disorder. Circulating levels of myeloperoxidase (MPO), as an oxidative stress marker, as well as matrix metalloproteinase-9 (MMP-9), as a destabilizer of plaques, are known to be elevated in patients with CAD and are associated with worse prognosis. Some studies have suggested that OSA is associated with MPO and MMP-9, but the effect of OSA on these biomarkers in cardiac cohorts is unknown. (2) Aims: We addressed the determinants of high MPO and MMP-9 in a CAD cohort with concomitant OSA. (3) Materials and Methods: The current study was a secondary analysis of the RICCADSA trial that was conducted in Sweden between 2005 and 2013. A total of 502 revascularized CAD patients with OSA (apnea-hypopnea index [AHI] ≥ 15 events/h; n = 391) or no-OSA (AHI < 5 events/h; n = 101), based on a home sleep apnea test, and who had blood samples at baseline were included in the analysis. The patients were dichotomized into a high or low MPO and MMP-9 groups, based on the median cut-off values. (4) Results: The mean age of the participants was 63.9 (±8.6), and 84% of the study cohort were men. Median values of MPO and MMP-9 levels were 116 ng/mL and 269 ng/mL, respectively. In different multivariate linear and logistic regression models, neither OSA nor OSA severity in terms of AHI and oxygenation indices were associated with the high MPO and MMP-9 levels. Current smoking was significantly associated with both high MPO (odds ratio [OR] 1.73, 95% confidence interval [CI] 1.06-2.84; p = 0.030) and high MMP-9 levels (OR 2.41, 95% CI 1.44-4.03; p < 0.001), respectively. Other significant determinants were revealed as beta blocker use (OR 1.81, 95% CI 1.04-3.16; p = 0.036) for high MPO as well as male sex (OR 2.07, 95% CI 1.23-3.50; p = 0.006) and calcium antagonist use (OR 1.91, 95% CI 1.18-3.09; p = 0.008) for high MMP-9 levels. (5) Conclusions: Current smoking, but not OSA, was significantly associated with high MPO and MMP-9 levels in this revascularized CAD cohort. Smoking status should be seriously taken into consideration while evaluating the effects of OSA and its treatment on long-term adverse cardiovascular outcomes in adults with CAD.