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Session: Nutritional Immunology and Inflammation (Poster Theater Flash Session 21)

(PTFS21-02-24) Human Milk Oligosaccharides and Bifidobacteria Infantis Interactively Shape Mouse Splenic Immune Responses

Tuesday, July 2, 2024
8:04 AM – 8:08 AM CT
Location:  W185A-C
Objectives: To determine the influence of human milk oligosaccharides and Bifidobacterium longum subsp. Infantis ATCC 1569 on immune response in a germ-free mouse model. 

Methods: 21-day-old germ-free mice (C57BI/6) were randomly assigned to four groups (n =10/group). The human milk oligosaccharides (HMOs) group was gavaged with 15 mg/day of pooled HMOs (2'-fucosyllactose, 3'-sialyllactose and lacto-N-neotetraose) throughout the 14-day experimental period. The B. Infantis (BI) group was gavaged with 1x109 CFU BI/d on d1, 4 and 9, while the BI +HMOs group was gavaged with pooled HMOs and BI. The control group (CON) was gavaged with phosphate-buffered saline. At termination, tissue weights (spleen, kidney, brain, and caecum) were recorded. Further, splenic immune cell populations were assessed using flow cytometry. Flow cytometry data were analyzed using a beta-regression model in R to evaluate the main effects of BI and HMO and BI × HMO interaction effects on immune response.

Results: Spleen weight (% of body weight) was higher, while caecum weight was lower in mice receiving HMO vs BI. An interaction of BI×HMO on adaptive immune cells, e.g., CD4+ helper T-cell type 1 cells, was observed with higher relative abundance (%) in the HMO vs BI and HMO+BI group (4.7% vs 3.5%, 3.8%), whereas dendritic cells were higher in the HMO+BI group vs HMO group (2.2% vs 1.1%). CD4+ cells were higher in BI groups with and without HMO (63.1%, 64.6%) vs CON (60.3%), while CD8+ cells were lower in BI groups with and without HMO (33.9%; 32.2%) compared to the CON (36.6%). In addition, TH17 cells were elevated in the BI group vs HMO group (1.3% vs 0.9%). In comparison, the Innate Lymphoid Cell (ILC) type 2 cell population were higher in the HMO group vs BI and HMO+BI groups (1.6 vs, 1.2%, 0.8%), while ILC1 cells were lower in BI relative to all the groups (34.2% vs 43.7%, 43.8%, 44.5%). ILC3 cells were higher in the HMO compared to all the other groups (2.2% vs 1.5%, 1.6%, 1.7%).

Conclusions: HMOs and BI shape innate and adaptive T cell populations differently, with an interaction of BI and HMOs on helper and cytotoxic T cells in gnotobiotic mice. This research highlights the distinct and interactive effects of BI and HMO on immune responses.

Funding Sources: USDA-ARS