Noninvasive rapid detection of metabolic adaptation in activated human T lymphocytes by hyperpolarized 13C magnetic resonance

Abstract

The metabolic shift induced in human CD4 + t lymphocytes by stimulation is characterized by an upregulation of glycolysis, leading to an augmentation in lactate production. this adaptation has already been highlighted with various techniques and reported in several previous studies. We herein propose a method to rapidly and noninvasively detect the associated increase in flux from pyruvate to lactate catalyzed by lactate dehydrogenase using hyperpolarized 13 c magnetic resonance, a technique which can be used for in vivo imaging. it was shown that the conversion of hyperpolarized 13 c-pyruvate to 13 C-lactate during the one-minute measurement increased by a mean factor of 3.6 in T cells stimulated for 5 days as compared to resting T cells. This method can be extended to other metabolic substrates and is therefore a powerful tool to noninvasively analyze t cell metabolism, possibly in vivo.Our dual parallel measurements (activated vs. resting T cells) could be extended to a larger number of parallel measurements using an integrated microfluidic system 46 , for instance to compare T cells that have been stimulated for a number of different time periods in a single measurement. HP 13 C MR can also be used to directly and noninvasively analyze the behavior of T cells in presence of antigens, possibly in vivo. Since it is well known that cancer cells will also compete for pyruvate 21 , HP [1-13 C]pyruvate might however not be the ideal substrate to detect T cell activation in the tumor microenvironment and alternative HP 13 C tracers shall be tested. We therefore plan on extending the proposed method to other metabolic substrates such as fatty acid and glutamine, the uptake and metabolism of which is also known to be altered in T lymphocytes upon activation 11 .

Multi‐sample measurement of hyperpolarized pyruvate‐to‐lactate flux in melanoma cells

“…This effect arises because the gyromagnetic ratio of deuterium is ~7‐fold weaker than that of protium, leading to weaker dipolar interactions 30 . Previous methods of multiple‐sample spectral acquisition using a single dissolution have been limited to two 31 or three 32 independent samples. The method we present here, combining a microcoil design allowing for rapid cell suspension sample load/unload/reload capability and the extended hyperpolarized lifetime of [1‐ 13 C] pyruvate dissolved in D 2 O, enabled up to eight reproducible high‐throughput measurements of pyruvate‐to‐lactate metabolic flux in multiple independent samples using a single HP dissolution.…”

Hyperpolarized 13C magnetic resonance imaging for noninvasive assessment of tissue inflammation

“…This metabolic signature was detectable through hyperpolarized [1‐ 13 C]pyruvate to [1‐ 13 C]lactate flux in an in vitro T cell culture 56 . As with the macrophage models, increased [1‐ 13 C]lactate (the sum of both intracellular and extracellular lactate) production was associated with increased expression of LDH and an increased lactate/pyruvate ratio in stimulated cultures compared with resting state T cells 54,56 …”

“…Activation of regulatory T cells rapidly increases their metabolic demand to sustain proliferation and function; this is largely met by upregulation of glycolysis. A recent study of soluble anti‐CD28–activated human T cells demonstrated the applicability of hyperpolarized 13 C MRS for measurements of immune cell function 56 . Stimulated regulatory T cells exhibit a similar pattern in their metabolic shift to that seen in macrophages, with an upregulation of glycolysis leading to increased lactate production 56 .…”

“…A recent study of soluble anti‐CD28–activated human T cells demonstrated the applicability of hyperpolarized 13 C MRS for measurements of immune cell function 56 . Stimulated regulatory T cells exhibit a similar pattern in their metabolic shift to that seen in macrophages, with an upregulation of glycolysis leading to increased lactate production 56 . This metabolic signature was detectable through hyperpolarized [1‐ 13 C]pyruvate to [1‐ 13 C]lactate flux in an in vitro T cell culture 56 .…”

Glycolytic metabolism of pathogenic T cells enables early detection of GvHD by13C-MRI

“…To overcome this limitation 13 C-labeled metabolites detected by spectroscopic magnetic resonance imaging (MRI) have become increasingly used for functional imaging primarily in the setting of malignancy [25][26][27][28][29][30] , and more recently in other inflammatory conditions 31,32 . Ex vivo dynamic nuclear hyperpolarization (DNP) of the 13 C-pyruvate tracer prior to infusion has improved the sensitivity of its MRI detection to allow real-time spectroscopic measurement of in vivo glycolytic activity within tissues in preclinical and clinical studies 33,34 . An additional benefit of this methodology is the lack of exposure to radioactivity from the tracer and/or scanner.…”