Effects of positive airway pressure therapy on cardiovascular and metabolic markers in males with obstructive sleep apnea

Association between elevated homocysteine levels and obstructive sleep apnea hypopnea syndrome: a systematic review and updated meta-analysis

Objective

This study aimed to distinguish between healthy controls and patients with OSAHS regarding homocysteine (HCY) levels and investigate how individuals with OSAHS respond to continuous positive airway pressure ventilation (CPAP) in terms of serum and plasma HCY levels.

Methods

To ascertain published articles about OSAHS, an exhaustive search was performed across medical databases, encompassing PubMed, Web of Science, EMBASE, CNKI, and Cochrane Library, until January 2, 2024. This study reviewed the literature regarding HCY levels in individuals with OSAHS and control groups, HCY levels under pre- and post-CPAP treatment, the Pearson/Spearman correlation coefficients between HCY levels and apnea-hypopnea index (AHI), and the hazard ratio (HR) of HCY levels concerning the occurrence of major adverse cerebrocardiovascular events (MACCEs) in patients with OSAHS. Meta-analyses were performed using weighted mean difference (WMD), correlation coefficients, and HR as effect variables. The statistical analysis was conducted using the R 4.1.2 and STATA 11.0 software packages.

Results

In total, 33 articles were selected for the final analysis. The OSAHS group exhibited significantly higher serum/plasma HCY levels than the control group (WMD = 4.25 μmol/L, 95% CI: 2.60-5.91, P< 0.001), particularly among individuals with moderate and severe OSAHS. Additionally, subgroup analysis using mean age, ethnicity, mean body mass index, and study design type unveiled significantly elevated levels of HCY in the serum/plasma of the OSAHS group compared to the control group. CPAP treatment can significantly decrease serum/plasma HCY levels in patients with OSAHS. Moreover, elevated HCY levels in individuals with OSAHS could be one of the risk factors for MACCEs (adjusted HR = 1.68, 95% CI = 1.10-2.58, P = 0.017). AHI scores show a positive correlation with serum/plasma HCY levels.

Conclusion

Patients with OSAHS had elevated serum/plasma HCY levels compared to healthy controls; however, CPAP therapy dramatically decreased HCY levels in patients with OSAHS. In patients with OSAHS, elevated HCY levels were linked with an increased risk of MACCEs, and HCY was positively connected with AHI values. HCY levels may serve as a useful clinical indicator for determining the severity and efficacy of OSAHS treatments.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024498806.

Redox-Oligomeric State of Peroxiredoxin-2 and Glyceraldehyde-3-Phosphate Dehydrogenase in Obstructive Sleep Apnea Red Blood Cells under Positive Airway Pressure Therapy

In this study, we examined the effect of six months of positive airway pressure (PAP) therapy on Obstructive Sleep Apnea (OSA) red blood cell (RBC) proteome by two dimensional difference gel electrophoresis (2D-DIGE) - based proteomics followed by Western blotting (WB) validation. The discovered dysregulated proteins/proteoforms are associated with cell death, H2O2 catabolic/metabolic process, stress response, and protein oligomerization. Validation by nonreducing WB was performed for peroxiredoxin-2 (PRDX2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) by using antibodies against the sulfinylated/sulfonylated cysteine of these proteins to better evaluate their redox-oligomeric states under OSA and/or in response to PAP therapy. The results indicated that the redox-oligomeric state of GAPDH and PRDX2 involving overoxidation by sulfinic/sulfonic acids were differentially modulated in OSA RBC, which might be compromising RBC homeostasis. PAP therapy by restoring this modulation induced a higher oligomerization of overoxidized GAPDH and PRDX2 in some patients that could be associated with eryptosis and the chaperone "gain" of function, respectively. This varied response following PAP may result from the complex interplay between OSA and OSA metabolic comorbidity. Hence, information on the redox status of PRDX2 and GAPDH in RBC will help to better recognize OSA subtypes and predict the therapeutic response in these patients. GAPDH monomer combined with body mass index (BMI) and PRDX2 S-S dimer combined with homeostatic model assessment for insulin resistance (HOMA-IR) showed to be very promising biomarkers to predict OSA and OSA severity, respectively.

Plasma Homocysteine and Autonomic Nervous Dysfunction: Association and Clinical Relevance in OSAS

Objective

Elevated plasma homocysteine (Hcy) is an independent risk factor for cardiovascular diseases, but the precise mechanism of Hcy in cardiovascular disease remains elusive. This study is aimed at evaluating the association between Hcy levels and autonomic nervous system and at investigating their clinical relevance in obstructive sleep apnea syndrome (OSAS).

Methods

A total of 191 subjects with OSAS were enrolled for this cross-sectional study. Heart rate variability (HRV) represents the status of the autonomic nervous system and is a well-known index that allows studying the autonomic modulation. HRV and polysomnography parameters were collected based on Holter monitors and polysomnography system. The software computed all the basic HRV parameters including SDANN, SDNN and pNN50. Correlation analyses between Hcy and HRV parameters and echocardiographic parameters were performed.

Results

Compared with the mild-moderate OSAS group, the prevalence of male and smoking and Hcy levels were considerably higher in the severe OSAS group (P = 0.01, P = 0.02, and P = 0.01, respectively). Also, there were significant linear relationships between Hcy quartiles with the proportion of severe OSAS (P = 0.01 for the trend). Interesting, there is a negative linear correlation between SDANN and Hcy quartiles (P = 0.02 for the trend). Spearman's correlation analysis showed a significant negative correlation between SDANN and Hcy levels (r = -0.17, P = 0.02). Interestingly, the relationship of it remains significant after adjustment for clinical covariates (r = -0.15, P = 0.04). However, echocardiographic parameters were not significantly correlated with Hcy or HRV parameters (all P > 0.05).

Conclusions

Elevated plasma Hcy level is linearly correlated with cardiac autonomic nervous function disorders in patients with OSAS.