Effects of CPAP on visceral adipose tissue in patients with obstructive sleep apnea: a meta-analysis.

PURPOSE: The efficacy of obstructive sleep apnea (OSA) treatment with continuous positive airway pressure (CPAP) on visceral adipose tissue (VAT) yielded conflicting results. This meta-analysis was performed to assess whether OSA treatment with CPAP could reduce VAT. METHODS: The PubMed, Cochrane Library, Embase, and Web of Science were searched before April 2019. Information on characteristics of study participants, pre- and post-CPAP treatment of VAT, and study design was utilized for analysis. Standardized mean difference (SMD) and 95% confidence interval (CI) were used to fully analyze the overall effects. Eleven studies were obtained and the meta-analysis was performed using RevMan v.5.2 and STATA 12.0. RESULTS: A total of 11 studies (16 cohorts) were pooled into meta-analysis, which included 398 patients. The value of VAT before and after CPAP treatment showed no change in OSA patients (SMD = - 0.02, 95% CI - 0.16 to 0.12, z = 0.24, p = 0.81). Subgroup analyses were further conducted, which revealed that age, gender distribution, baseline body mass index, daily duration, CPAP therapy duration, measure, sample size, and study design did not affect the results. CONCLUSIONS: This meta-analysis revealed that CPAP therapy has no effect on VAT in OSA patients. Further large-scale, well-designed randomized controlled trials are required to address this issue.

miR-146a-5p Mediates Intermittent Hypoxia-Induced Injury in H9c2 Cells by Targeting XIAP.

MicroRNAs (miRNAs) have emerged as key modulators in the pathophysiologic processes of cardiovascular diseases. However, its function in cardiac injury induced by obstructive sleep apnea (OSA) remains unknown. The aim of the current study was to identify the effect and potential molecular mechanism of miR-146a-5p in intermittent hypoxia(IH)- induced myocardial damage. We exposed H9c2 cells to IH condition; the expression levels of miR-146a-5p were detected by RT-qPCR. Cell viability, cell apoptosis, and the expressions of apoptosis-associated proteins were assessed via Cell Counting Kit-8 (CCK-8), flow cytometry, and western blotting, respectively. Target genes of miR-146a-5p were confirmed by dual-luciferase reporter assay. IH remarkably lowered viability but enhanced cell apoptosis. Concomitantly, the miR-146a-5p expression level was increased in H9c2 cells after IH. Subsequent experiments showed that IH-induced injury was alleviated through miR-146a-5p silence. X-linked inhibitor of apoptosis protein (XIAP) was predicted by bioinformatics analysis and further confirmed as a direct target gene of miR-146a-5p. Surprisingly, the effect of miR-146a-5p inhibition under IH may be reversed by downregulating XIAP expression. In conclusion, our results demonstrated that miR-146a-5p could attenuate viability and promote the apoptosis of H9c2 by targeting XIAP, thus aggravating the H9c2 cell injury induced by IH, which could enhance our understanding of the mechanisms for OSA-associated cardiac injury.