Aspirin intervention, inflammation and the oral microbiome

Abstract

Specific pro-inflammatory oral taxa have been shown to be increased in the gut microbiome of individuals with colorectal cancer (CRC). Aspirin is associated with decreased risk of colorectal cancer, potentially by modulating the gut and the oral microbiome. However, it remains unclear how pro-inflammatory oral taxa would respond to anti-inflammatory agents such as aspirin. In this dissertation, we aimed to evaluate the effect of aspirin intervention on specific pro-inflammatory oral taxa and inferred functional traits linked to inflammation in a 6-week double-blind placebo-controlled trial.In the first manuscript, we evaluated the effect of aspirin intervention on the relative abundance of pro-inflammatory oral taxa. We found that the change over-time in the relative abundance of 9 out of the 12 pre-specified taxa at the genus level, and 1 out of 2 pre-specified taxa at the family level differed between the aspirin and placebo groups. These preliminary findings suggest that aspirin may change the relative abundance of oral taxa associated with inflammation. In manuscript 2, we evaluated the effect of aspirin intervention on the relative abundance of inferred functional traits linked to the pro-inflammatory bacterial metabolite, lipopolysaccharide (LPS). We did not find an association between aspirin intervention and the change in relative abundance of inferred functional traits for LPS. However, we observed a positive correlation between the relative abundance of pro-inflammatory oral taxa and the relative abundance of inferred functional traits for LPS. These findings are in line with the current literature on bacterial virulence factors. Lastly, we investigated whether inflammation-related oral taxa and inflammation-related gut taxa are correlated and whether oral and gut microbiome communities respond similarly to aspirin. Our results show that aspirin may induce changes in oral and gut alpha diversity in a similar fashion. In addition, our findings of an inverse correlation between SCFA-producing gut taxa and pro-inflammatory oral taxa suggest that studying oral taxa may be important to understanding the link between inflammation and the gut microbiome. Overall, these findings are in line with a growing body of evidence highlighting the role of the oral microbiome in chronic inflammatory disorders of the intestine, including CRC.