# Impact of obstructive sleep apnea on gut microbiome of patients with symptomatic intracranial atherosclerotic stenosis

## TL;DR

This study finds that obstructive sleep apnea affects gut bacteria in patients with brain artery narrowing, altering harmful and beneficial microbes.

## Contribution

The study is the first to explore how obstructive sleep apnea impacts gut microbiota in patients with symptomatic intracranial atherosclerotic stenosis.

## Key findings

- Patients with OSAS showed increased harmful gut microbes like Escherichia-Shigella and decreased beneficial bacteria like Blautia.
- Microbial metabolic pathways related to biosynthesis were downregulated in OSAS patients.
- Changes in gut microbiota were significantly associated with the severity of sleep apnea (AHI).

## Abstract

Obstructive sleep apnea syndrome (OSAS) is positively associated with increased risks of ischemic stroke. Patients with stroke exhibit remarkable gut microbiota dysbiosis. However, the impact of OSAS on gut microbiota of patients with symptomatic intracranial atherosclerotic stenosis (sICAS), one of the most common causes of stroke, remains unknown.

This study included patients with sICAS, the severity of OSAS was defined by the apnea-hypopnea index (AHI). AHI < 5 was considered no sleep apnea, AHI 5–15 was defined as mild OSAS, AHI 15–30 as moderate OSAS, and AHI > 30 as severe OSAS. Fecal samples were collected and subjected to 16 s rRNA gene sequencing. PICRUSt2 was used to predict the functional properties of the bacterial communities.

In total, 99 sICAS patients were included, with No-OSAS (N = 22), Mild (N = 25), Moderate (N = 30), and Severe (N = 22). Patients with OSAS exhibited significantly altered gut microbiota composition compared to those without sleep apnea, characterized by increased abundances of pathogens such as Escherichia-Shigella and decreased abundances of beneficial microbes such as short-chain fatty acids-producing bacteria Blautia. Importantly, these microbes were significantly associated with AHI. Several microbial metabolic pathways such as Peptidoglycan biosynthesis, C5-branched dibasic acid metabolism, and Pantothenate and CoA biosynthesis were downregulated with OSAS.

OSAS is associated with gut dysbiosis and altered microbial metabolic functions in patients with sICAS.