D0636 - History of Tonsillectomy Is Seen to Have a Minimal Impact on the Small Intestinal Microbiome

Introduction: Tonsillar tissue is an important immune reservoir and serves as an early activator of the immune system. Despite the link with infection and immunity, to date there is no study examining the effect of tonsillectomy on the small bowel microbiome. Here, we compare small bowel microbial profiles in subjects with or without tonsillectomy.

Methods: The REIMAGINE study is a novel large-scale study using validated methods for duodenal aspirate collection and microbiome sequencing in subjects undergoing upper endoscopy without colon prep. Subjects were divided into 2 groups: Self-reported undergoing a tonsillectomy (T+), and those who did not undergo a tonsillectomy (T-). Groups were matched for sex, age ±5 years, and BMI ±3 kg/m². Duodenal aspirates were collected, and microbial DNA isolated using the MagAttract PowerSoilDNA Kit. V3 and V4 libraries were sequenced on MiSeq. Reference based Operational Taxonomic Unit clustering was performed using SILVA v132 database. Taxonomic analyses were performed with CLC Microbial Genomics Module v.2.5 and MicrobiomeAnalyst. Blood was collected for inflammatory biomarkers and biochemical analysis, including lipid and glucose profiles.

Results: 253 subjects were included (T+, N=126, mean age = 62±15, mean BMI = 26.12±5.55) (T-, N=127, mean age = 63±13, mean BMI = 25.62±5.75). There was no significant difference in blood level of any analyte between groups. There was no statistical difference in duodenal microbial alpha-diversity (P >0.05) or beta-diversity (P >0.05) between the T+ group and T- group (Fig1a,b). The most prevalent phylum in the core duodenal microbiome of the T+ group was Firmicutes, followed by Actinobacteria and Proteobacteria. While Firmicutes was also the most prevalent phylum in the T- group, Proteobacteria moved up in rank to the second most prevalent phylum, and Actinobacteria dropped to third most prevalent. There were no major higher order taxonomic differences between T+ and T- groups (Fig1c). At genus level, Streptococcus (FC= 0.1, FDR P-value=1) (an organism known to infect the oropharynx) was not significantly different between groups. The only genus change observed was an increase in the relative abundance of Granulicatella in the T+ group (FC= 2.02, FDR P-value=0.01).

Discussion: Our findings demonstrate that history of tonsillectomy was associated with very few changes in the small bowel microbiome. Of note, organisms such as Streptococcus were not altered in subjects with prior tonsillectomy.