Deriving Conventional Dendritic Cells from ER-Hoxb8 Immortalized Hematopoietic Stem and Progenitor Cells & Evaluating CD36 Dependent Uptake of Oxidized Low-Density Lipoprotein in Type 1 Conventional Dendritic Cells
Date
2024-04-19
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Abstract
Dendritic cells (DCs) play a crucial role in immunity, acting as professional antigen presenting cells (APCs) that bridge the innate and adaptive immune systems through antigen presentation. Among DC subtypes, type 1 conventional dendritic cells (cDC1s) excel in cross-presentation, which allows for the loading of processed antigen onto MHC I and is believed to be the primary means by which naïve CD8 T cells are converted into effector CD8 T cells. Despite comprising a small fraction of the total leukocyte population, cDC1s are disproportionately important in tumor environments, where their presence correlates with improved patient survival and treatment response across multiple cancers. However, studying cDCs poses challenges due to limited tools and inefficient methods for obtaining primary murine cDC1s. To address this, we developed a system that consistently provides high yields of cDCs, utilizing an easily accessible cell line of immortalized cDC progenitors. Using fluorescence activated cell sorting (FACS), we enriched an FLT3L-driven Hoxb8-immortalized hematopoietic stem and progenitor (HSPC) cell line to obtain a pre-cDC progenitor population. We then optimized existing methods of obtaining cDCs from bone marrow to consistently obtain cDC populations from our immortalized cDC progenitor cell line. Subsequently, we confirmed that this approach yields cDC subset compositions comparable to those obtained using established primary bone marrow protocols. Additionally, we investigated the role of CD36, a receptor for oxidized low-density lipoprotein (oxLDL), in cDC1s. We demonstrated a significant reduction in oxLDL uptake in cDCs lacking CD36, as well as in cDCs under the influence of macropinocytosis inhibiting drugs, suggesting that CD36-assisted macropinocytosis facilitates oxLDL uptake in cDC1s, ultimately leading to lipid body formation akin to macrophage foam cells. After replicating a commonly observed decrease in cross-presentation abilities in lipid-laden cDC1s, we provided a potential mechanism for this impairment, suggesting that a disruption in the recruitment of apolipoprotein 7c (APOL7C), which is vital to successful cross presentation, may be attributed to a significant oxLDL-dependent delay in phagosomal maturation. In summary, our research sheds light on the interplay between CD36, oxLDL, and cDC1s, offering valuable insights for future cDC studies and providing a promising tool for investigating their roles in immunity and disease.
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Keywords
Dendritic Cell, Immunology, CD36, Hematopoiesis, Antigen Presentation, Cross Presentation, cDC1, oxLDL, Phagocytosis, Endocytosis, Phagosome Maturation, Apolipoprotein, T Cell
Citation
Moore, M. R. (2024). Deriving conventional dendritic cells from ER-Hoxb8 immortalized hematopoietic stem and progenitor cells & evaluating CD36 dependent uptake of oxidized low-density lipoprotein in type 1 conventional dendritic cells (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.