{Reference Type}: Journal Article {Title}: Association between Circulating T Cells and the Gut Microbiome in Healthy Individuals: Findings from a Pilot Study. {Author}: Vivek S;Shen YS;Guan W;Onyeaghala G;Oyenuga M;Staley C;Karger AB;Prizment AE;Thyagarajan B; {Journal}: Int J Mol Sci {Volume}: 25 {Issue}: 13 {Year}: 2024 Jun 21 {Factor}: 6.208 {DOI}: 10.3390/ijms25136831 {Abstract}: Though the microbiome's impact on immune system homeostasis is well documented, the effect of circulating T cells on the gut microbiome remains unexamined. We analyzed data from 50 healthy volunteers in a pilot trial of aspirin, using immunophenotyping and 16S rRNA sequencing to evaluate the effect of baseline T cells on microbiome changes over 6 weeks. We employed an unsupervised sparse canonical correlation analysis (sCCA) and used multivariable linear regression models to evaluate the association between selected T cell subsets and selected bacterial genera after adjusting for covariates. In the cross-sectional analysis, percentages of naïve CD4+ T cells were positively associated with a relative abundance of Intestinimonas, and the percentage of activated CD8+ T cells was inversely associated with Cellulosibacter. In the longitudinal analysis, the baseline percentages of naïve CD4+ T cells and activated CD4+ T cells were inversely associated with a 6-week change in the relative abundance of Clostridium_XlVb and Anaerovorax, respectively. The baseline percentage of terminal effector CD4+ T cells was positively associated with the change in Flavonifractor. Notably, the microbiome taxa associated with T cell subsets exclusively belonged to the Bacillota phylum. These findings can guide future experimental studies focusing on the role of T cells in impacting gut microbiome homeostasis.