## 4 Discussion  
As far as we are aware, this is the first pilot study to analyze the association between the intestinal microbiome and atherosclerosis in adult patients with OSA, with and without atherosclerosis. LEfSe, alpha and beta diversity, PCA analyses as well as plots show relative abundances were made for a detailed analysis of the differences between the two groups. Furthermore, we examined the correlation between the alpha diversity and the maximal CCA IMT, as well as the difference between the atherosclerotic and non-atherosclerotic samples for each microbe at genus taxonomic level. Figure 17: The median and the interquartile range of the fractions of _Peptostreptococcaceae_. Figure 18: The candidate microbes at the genus taxonomic level without correction in the two groups. With LEfSe analysis at 4 taxonomic levels, we found in total 15 taxa significantly more abundant in the non-atherosclerotic group and 10 taxa in the atherosclerotic group. With alpha diversity analyses at phylum and genus taxonomic levels, we did not find a significant difference between the two groups. With beta diversity analyses at 4 taxonomic levels, we did not find visible clustering in the PCoA space. With PCAs at 4 taxonomic levels, we did not find visible clustering in PCA space. We discovered that higher maximal CCA IMT is significantly correlated with lower phylum-level diversity. This preliminary finding is consistent with another study [5], in which [PERSON] et al. examined 92 adult Caucasian people from the Moscow region with no clinical cardiovascular or other chronic diseases and found a higher IMT within the cluster of lower alpha diversity after carotid ultrasound examinations and stool sample 165 rRNA sequencing. It should be noted that the presence of OSA was not investigated. They also reported links between certain bacteria and various metabolic status, such as a higher proportion of _Prerotella_--which is included in our results as one of the candidate microbes in the atherosclerotic group--being associated with general and abdominal obesity. Although there was no significant difference in alpha diversity between groups with high and normal IMT in our previous study [4], this can be attributed to the smaller sample size compared to the Moscow study. Gut dysbiosis has been linked to many risk factors for atherosclerosis, including diabetes [29; 30], obesity [30; 31], and smoking [32]; whereas the normal microbiota (commensal bacteria) has been shown to possibly protect against the development of atherosclerosis [33]. Aside from various microbial metabolites, one possible pathological process is the dysbiosis-associated leaky gut-induced immune response by the host. Dysbiosis leads to the translocation of lipopolysaccharide-LPS to the bloodstream by compromising the gut barrier, LPS can activate Toll-like receptor 4 signaling and decrease reverse cholesterol transport (RCT) to exacerbate atherosclerosis [34; 35; 36]. The relationship between the gut microbiome and disease is a complex process and is still under investigation, where our preliminary findings support the importance of dysbiosis in the development of atherosclerosis. We discovered a significantly lower level of _Peptostreptococcaceae_ in atherosclerotic subjects, which contradicts previous research. Using computer-assisted image processing to calculate the amount of atherosclerosis and 165 rRNA sequencing for microbiome profiling, [PERSON] et al. tested whether intermittent hypoxia (IH) or intermittent hypercapnia (IC) changes the metabolome and microbiota to cause a pro-atherosclerotic condition after 4-week IH or IC conditions. They found that _Peptostreptococcaceae_ increased in relative abundance two weeks before atherosclerosis appeared, demonstrating that _Peptostreptococcaceae_ contributes to the development of IH- and IC-induced atherosclerosis in Apolipoprotein E knock-out mice (ApoE\(-\)/\(-\)) [17].