Abstract A04: Effects of aspirin intervention on health and disease-associated oral bacterial taxa
Authors: Chinedu Guillaume C. , Staley Christopher M. , Demmer Ryan T. , Aasma Shaukat , Church Tim R. , Prizment Anna E. 
Published: December 2020

Abstract
Background: Several bacterial taxa that are consistently enriched in the gut microbiome of CRC cases are also found in the oral cavity. They exhibit phenotypic traits such as adherence to host epithelial cells, mucus degradation, and biofilm formation, which promote bacterial survival in the colon and may play a role in both oral disease and colorectal carcinogenesis by stimulating an inflammatory response. We evaluated the effect of a 6-week aspirin intervention on the relative abundance of oral bacterial taxa in a randomized placebo-controlled trial.
Methods: Fifty healthy subjects, 50-75 years old, were randomized to receive either aspirin (N=30) or placebo (N=20) for 6 weeks. Oral samples were collected at baseline and after treatment (6 weeks) and amplicon sequencing of the V4 region of the 16S rRNA gene was done using Illumina MiSeq technology. The data were analyzed using the standard DADA2 workflow. We used linear regression analysis, PERMANOVA, and negative binomial regressions (DESeq2 package) to assess the association between intervention assignment (aspirin vs. placebo) and α-diversity, β-diversity, and fold change in specific taxa, after adjustment for age, gender, and BMI at baseline and postintervention. Intervention assignment was hypothesized to influence the following bacterial taxa a priori: Fusobacterium, Porphyromonas, Prevotella, Gemella, Neisseria, Streptococcus, Haemophilus, Campylobacter, Veillonella, Actinomyces based on previous studies. We estimated the association between aspirin use and the changes in the relative abundance of the specified taxa from pre- to post-treatment (baseline to week 6) using a mixed-effect regression model (lme4 package) with a binomial distribution in which the log of odds ratio (β estimate) for the interaction term compared aspirin to placebo intervention for post- versus pretreatment.
Results: Aspirin treatment was not associated with α- or β- diversity at baseline or postintervention. However, the change in relative abundance of 8 out of the 10 prespecified taxa over time differed between the aspirin and placebo groups. In the aspirin group, there were greater increases in the relative abundances of Neisseria, Streptococcus, Actinomyces, and greater decreases in the relative abundance of Prevotella, Veillonella, Fusobacterium, and Porphyromonas.
Conclusions: These preliminary findings suggest that aspirin may change the relative abundance of oral taxa associated with oral dysbiosis or CRC. Further studies are needed to understand the impact that the duration and dosage of the aspirin intervention may have on the oral microbiome.
Citation Format: Guillaume C. Chinedu, Christopher M. Staley, Ryan T. Demmer, Shaukat Aasma, Tim R. Church, Anna E. Prizment. Effects of aspirin intervention on health and disease-associated oral bacterial taxa [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr A04.