Andrew Li
Research Mentor: Yasmina Laouar
Mentor Department: Microbiology and Immunology, Medicine
Author(s): Andrew Li, Yasmina Laouar, Xin Sun
Session: Session 4 (1:00 PM – 1:50 PM)
Presentation Type: Poster 27
Abstract
The most common mouse strain used in research laboratories is the C57BL/6 mouse due to their genetic proximity to humans, traditionally housed in Specific Pathogen-free (SPF) environments which limit microbial exposure, ensure animal welfare, and create optimal experimental reproducibility. But the environment humans live in is greatly different from the pristine conditions of the SPF mouse, meaning the traditional SPF model creates gaps in our understanding of how the introduction of pathogens could affect immune system compositions. A solution to this gap is the dirty mouse model, in which mice are introduced to controlled pathogens/microbes. Despite growing interest, the immunological basis of dirty mouse models remains largely unexplored. In our research, we analyzed the immune cell compositions in mice with different levels of microbe exposure, including mice housed under SPF condition, co-housed mice (SPF mice housed with pet store mice), and pet store mice. We collected cell samples from 13 lymphoid and non-lymphoid organs for analysis. We utilized flow cytometry to analyze the expression of cell markers that define immune cell subsets. Focusing on the stem cell panel derived from the bone marrow cells, we exclude the mature immune cells using multiple lineage markers. The remaining immature cells consist of Hematopoietic Stem cells and Progenitor Cells (HSPCs) which self-renew and differentiate into mature blood cells. The remaining markers are used to break down the HSPCs into more specific categories, allowing for more targeted cell analysis. Because immature HSPCs directly control the development of mature cells, analyzing the differences in their expression allows us to assess how microbial contact influences stem cell renewal, a key process of immune system development. By comparing HSPCs across distinct housing conditions, this study defines how microbial exposure reshapes bone marrow immune activity, with lasting consequences for downstream immune lineages.
