401 - Dysbiosis induces age-dependent alterations in T cell subsets

Sunday, April 30, 2023

3:30 PM – 6:00 PM ET

Poster Number: 401
Publication Number: 401.334

Mariana R. Brewer, Cohen Children's Medical Center, New Hyde Park, NY, United States; Daniel Yu, The Feinstein Institutes for Medical Research, Manhasset, NY, United States; Clifford S. Deutschman, Cohen Children's Medical Center/Northwell Health, Manhasset, NY, United States; Matthew D. Taylor, Cohen Children's Medical Center, New Hyde Park, NY, United States

Presenting Author(s)

MB

Mariana R. Brewer, MD (she/her/hers)

Neonatology Attending
Cohen Children's Medical Center
New Hyde Park, New York, United States

Background: The microbiome and the T cell repertoire develop in parallel as we age. Broad-spectrum antibiotics have been used to interrupt normal microbiomic development and to induce dysbiosis. The effect of microbiomic development on the developing T cell repertoire has not been described. We hypothesize that altering microbiomic development will affect the development of the T cell repertoire.

Objective: Our objective is to characterize the effect of antibiotic-induced dysbiosis on the developing T cell repertoire.

Design/Methods:

Broad-spectrum enteral antibiotics (1gm/L of vancomycin, gentamicin, metronidazole, ampicillin in 2% sucrose) or vehicle (2% sucrose) were administered to 5-wk and 9-wk-old C57BL/6 mice for three continuous wks (n=5 in each group). Following treatment, at 8-wks and 12-wks, mice were euthanized, and spleens were harvested for flow cytometry to examine T cell subsets. Statistical significance (p< 0.05) was determined using 2-way ANOVA with Sidak’s correction for multiple comparisons.

Results: After induction of dysbiosis, all mice developed megacolon. At 8-wks old, dysbiotic mice had a lower absolute number of splenic T cells. Antibiotic-exposed mice also had lower numbers of total CD4 T cells and CD4 memory, naïve, and terminal effector T cell subsets. Although the absolute number of CD8 T cells was not affected by dysbiosis in either age group, 8-wk-old dysbiotic mice had a lower proportion of effector memory CD8 T cells than their unexposed counterparts. In contrast, the absolute number and proportion of regulatory T cells (FoxP3+ CD4+) was higher in 8-wk-old antibiotic exposed mice. Dysbiosis did not affect T cell total or subset numbers in 12-wk-old mice, but it did influence T cell activation. Specifically, antibiotic-exposed 12-wk-old mice had a higher proportion of CD69-positive memory, total CD4, and memory CD4 T cells compared to unexposed mice. Differences in CD69 expression were not noted in 8-wk-old mice.

Conclusion(s): Dysbiosis affects the T cell repertoire differently in young mice compared to older mice. Dysbiosis induction at 5 wks of age led to significant differences in the absolute numbers of various T cell subsets, which were not noted when dysbiosis was induced at 9 wks of age. In contrast, dysbiosis at 12 wks showed differences in the state of activation of CD4 T cells, specifically within the memory CD4 T cell subset. These results show that antibiotic exposure and the resultant dysbiosis, affect T cells differently based on age and could result in a differential effect on immune function.