Fatty Acid Uptake in T Cell Subsets Using a Quantum Dot Fatty Acid Conjugate

Megan E Muroski,Peng Zhang,Jason Miska,Aida Rashidi,Maciej S Lesniak,Haley Moore,Alan L Chang,Yu Han,Aurora Lopez-Rosas

doi:10.1038/s41598-017-05556-x

Megan E Muroski, Peng Zhang + Show 7 more

Open Access

https://doi.org/10.1038/s41598-017-05556-x

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Abstract

Fatty acid (FA) metabolism directly influences the functional capabilities of T cells in tumor microenvironments. Thus, developing tools to interrogate FA-uptake by T cell subsets is important for understanding tumor immunosuppression. Herein, we have generated a novel FA-Qdot 605 dye conjugate with superior sensitivity and flexibility to any of the previously commercially available alternatives. For the first time, we demonstrate that this nanoparticle can be used as a specific measure of fatty acid uptake by T cells both in-vitro and in-vivo. Flow cytometric analysis shows that both the location and activation status of T cells determines their FA uptake. Additionally, CD4+ Foxp3+ regulatory T cells (Tregs) uptake FA at a higher rate than effector T cell subsets, supporting the role of FA metabolism for Treg function. Furthermore, we are able to simultaneously detect glucose and fatty acid uptake directly within the tumor microenvironment. Cumulatively, our results suggest that this novel fluorescent probe is a powerful tool to understand FA utilization within the tumor, thereby providing an unprecedented opportunity to study T cell FA metabolism in-vivo.

Highlights

Tregs are a potently immunosuppressive subset of CD4+ T cells expressing the transcription factor Foxp[39], which accumulates in most solid tumors[10] including glioblastoma multiforme[11,12,13]
We demonstrate the ability to both append multiple lengths of Fatty acid (FA) to quantum dots and to append FA to broad-spectrum color quantum dots. This versatility allowed us to address the relative contribution of fatty acid uptake versus glucose uptake by T cells in-vivo, which, to our knowledge, is the first time this has been achieved
We have described a new method for determining fatty acid uptake of distinct T cell populations in-vivo

Summary

Introduction

Tregs are a potently immunosuppressive subset of CD4+ T cells expressing the transcription factor Foxp[39], which accumulates in most solid tumors[10] including glioblastoma multiforme[11,12,13]. The only method to simultaneously measure glucose and fatty acid uptake is based on fluorescent dyes with almost identical spectral characteristics[16, 17] This severely hampers the ability to understand the inherent complexity and heterogeneous nature of T cells. Determining cellular energy utilization within distinct cell subsets provides researchers with potential strategies for future cancer and immunotherapy applications To address these questions, we have developed a sensor for fatty acid uptake using fatty acids conjugated to the surface of a quantum dot. We demonstrate the ability to both append multiple lengths of FA to quantum dots and to append FA to broad-spectrum color quantum dots This versatility allowed us to address the relative contribution of fatty acid uptake versus glucose uptake by T cells in-vivo, which, to our knowledge, is the first time this has been achieved

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