Reversed metabolic reprogramming as a measure of cancer treatment efficacy in rat C6 glioma model

Deuterium metabolic imaging for 3D mapping of glucose metabolism in humans with central nervous system lesions at 3T

PURPOSE

To explore the potential of 3T deuterium metabolic imaging (DMI) using a birdcage 2 H radiofrequency (RF) coil in both healthy volunteers and patients with central nervous system (CNS) lesions.

METHODS

A modified gradient filter, home-built 2 H volume RF coil, and spherical k-space sampling were employed in a three-dimensional chemical shift imaging acquisition to obtain high-quality whole-brain metabolic images of 2 H-labeled water and glucose metabolic products. These images were acquired in a healthy volunteer and three subjects with CNS lesions of varying pathologies. Hardware and pulse sequence experiments were also conducted to improve the signal-to-noise ratio of DMI at 3T.

RESULTS

The ability to quantify local glucose metabolism in correspondence to anatomical landmarks across patients with varying CNS lesions is demonstrated, and increased lactate is observed in one patient with the most active disease.

CONCLUSION

DMI offers the potential to examine metabolic activity in human subjects with CNS lesions with DMI at 3T, promising for the potential of the future clinical translation of this metabolic imaging technique.

Reduced Th1 response is associated with lower glycolytic activity in activated peripheral blood mononuclear cells after metabolic and bariatric surgery

BACKGROUND

Obesity promotes cellular immunometabolism changes that trigger the activation of macrophages and lymphocytes, leading to systemic inflammation. Activated leukocytes undergo metabolic reprogramming, increasing glycolytic activity.

OBJECTIVE

To examine whether the reduction in the inflammatory state associated with bariatric surgery is associated with decreased glycolytic activity in leukocytes. Setting Single-center, prospective observational study.

METHODS

This study involved 18 patients with obesity undergoing bariatric surgery. All measurements were performed preoperatively and six months postoperatively. Peripheral blood mononuclear cells and plasma were obtained to determine the glycolytic rate and mitochondrial membrane potential as surrogates of the metabolic switching and high-sensitivity C-reactive protein, adipokines, and CD69 expression as inflammatory and activation markers.

RESULTS

Glycolytic activity engaged by CD3/CD28 activation was reduced six months after bariatric surgery, associated with decreased levels of T helper (Th) 1 and Th17 signature cytokines. An overall reduction in inflammatory markers was observed, which correlated with a higher adiponectin/leptin ratio.

CONCLUSIONS

Metabolic and bariatric surgery-induced weight loss leads to reprogramming in T cells' metabolic machinery, resulting in reduced stimulation of glycolysis after activation, which may explain the decrease in systemic inflammation mediated by cytokines such as interferon-γ and interleukin-17A.

Measuring the Metabolic Evolution of Glioblastoma throughout Tumor Development, Regression, and Recurrence with Hyperpolarized Magnetic Resonance

Rapid diagnosis and therapeutic monitoring of aggressive diseases such as glioblastoma can improve patient survival by providing physicians the time to optimally deliver treatment. This research tested whether metabolic imaging with hyperpolarized MRI could detect changes in tumor progression faster than conventional anatomic MRI in patient-derived glioblastoma murine models. To capture the dynamic nature of cancer metabolism, hyperpolarized MRI, NMR spectroscopy, and immunohistochemistry were performed at several time-points during tumor development, regression, and recurrence. Hyperpolarized MRI detected significant changes of metabolism throughout tumor progression whereas conventional MRI was less sensitive. This was accompanied by aberrations in amino acid and phospholipid lipid metabolism and MCT1 expression. Hyperpolarized MRI can help address clinical challenges such as identifying malignant disease prior to aggressive growth, differentiating pseudoprogression from true progression, and predicting relapse. The individual evolution of these metabolic assays as well as their correlations with one another provides context for further academic research.

Current human brain applications and challenges of dynamic hyperpolarized carbon-13 labeled pyruvate MR metabolic imaging

The ability of hyperpolarized carbon-13 MR metabolic imaging to acquire dynamic metabolic information in real time is crucial to gain mechanistic insights into metabolic pathways, which are complementary to anatomic and other functional imaging methods. This review presents the advantages of this emerging functional imaging technology, describes considerations in clinical translations, and summarizes current human brain applications. Despite rapid development in methodologies, significant technological and physiological related challenges continue to impede broader clinical translation.

Preoperative imaging of glioblastoma patients using hyperpolarized 13C pyruvate: Potential role in clinical decision making

Background

Glioblastoma remains incurable despite treatment with surgery, radiation therapy, and cytotoxic chemotherapy, prompting the search for a metabolic pathway unique to glioblastoma cells.¹³C MR spectroscopic imaging with hyperpolarized pyruvate can demonstrate alterations in pyruvate metabolism in these tumors.

Methods

Three patients with diagnostic MRI suggestive of a glioblastoma were scanned at 3 T 1–2 days prior to tumor resection using a ¹³C/¹H dual-frequency RF coil and a ¹³C/¹H-integrated MR protocol, which consists of a series of ¹H MR sequences (T₂ FLAIR, arterial spin labeling and contrast-enhanced [CE] T₁) and ¹³C spectroscopic imaging with hyperpolarized [1-¹³C]pyruvate. Dynamic spiral chemical shift imaging was used for ¹³C data acquisition. Surgical navigation was used to correlate the locations of tissue samples submitted for histology with the changes seen on the diagnostic MR scans and the ¹³C spectroscopic images.

Results

Each tumor was histologically confirmed to be a WHO grade IV glioblastoma with isocitrate dehydrogenase wild type. Total hyperpolarized ¹³C signals detected near the tumor mass reflected altered tissue perfusion near the tumor. For each tumor, a hyperintense [1-¹³C]lactate signal was detected both within CE and T₂-FLAIR regions on the ¹H diagnostic images (P = .008). [¹³C]bicarbonate signal was maintained or decreased in the lesion but the observation was not significant (P = .3).

Conclusions

Prior to surgical resection, ¹³C MR spectroscopic imaging with hyperpolarized pyruvate reveals increased lactate production in regions of histologically confirmed glioblastoma.

Optical and magnetic resonance imaging approaches for investigating the tumour microenvironment: state-of-the-art review and future trends

The tumour microenvironment (TME) strongly influences tumorigenesis and metastasis. Two of the most characterized properties of the TME are acidosis and hypoxia, both of which are considered hallmarks of tumours as well as critical factors in response to anticancer treatments. Currently, various imaging approaches exist to measure acidosis and hypoxia in the TME, including magnetic resonance imaging (MRI), positron emission tomography and optical imaging. In this review, we will focus on the latest fluorescent-based methods for optical sensing of cell metabolism and MRI as diagnostic imaging tools applied both in vitro and in vivo. The primary emphasis will be on describing the current and future uses of systems that can measure intra- and extra-cellular pH and oxygen changes at high spatial and temporal resolution. In addition, the suitability of these approaches for mapping tumour heterogeneity, and assessing response or failure to therapeutics will also be covered.

Confocal investigation on colocalization between tubulin posttranslational modifications and associated proteins in rat C6 glioma cells

Glioblastoma multiforme is the most lethal brain tumor. In the study of mechanisms underlying its development attention has been paid to the microtubular network of its cells, mainly on βIII tubulin, considered as a marker of malignancy. In the present work, we chose to investigate the tubulin code in glioblastoma cells, analyzing the degree of interaction between tubulin post-translational modifications and different proteins associated with them. The pattern of diverse associated proteins such as EB-1, CLIP-170 and kinesin-1 and their degree of co-distribution with the most abundant post-translational tubulin modifications (tyrosination, acetylation and polyglutamylation) were evaluated. Through immunofluorescence we have shown that EB-1, CLIP-170 and kinesin-1 were well detectable in glioblastoma cells. The double fluorescence and colocalization index between the post-translational modifications of tubulin and associated proteins showed that tyrosinated α-tubulin has significantly high affinity with EB-1, CLIP-170 and kinesin-1, while for acetylated and polyglutamylated tubulin, the degree of interaction with the three associated proteins evaluated was less apparent. Data presented in this paper underline the importance of a thorough analysis of the microtubular mechanics in glioblastoma cells. This may suggest new experimental therapeutic approaches able to act more selectively on the microtubular network of cells in this type of cancer.

MRI of [2-13 C]Lactate without J-coupling artifacts

PURPOSE

Imaging of [2-¹³ C]lactate, a metabolic product of [2-¹³ C]pyruvate, is over considerable interest in hyperpolarized ¹³ C studies. However, artifact-free imaging of a J-coupled nuclear spin species can be challenging due to the peak-splitting induced by the spin-spin interactions. In this work, two new techniques resolving these J-modulated artifacts are presented.

THEORY AND METHODS

The Product Operator Formalism (POF) of density matrix theory is used to both numerically and analytically derive the coherences arising during radiofrequency excitation and readout of a J-coupled spin system. A combination of computer simulations and experiments with [2-¹³ C]lactate and ¹³ C-formate phantoms are then used to verify the performance of two imaging methods. In the first approach, a quadrature imaging technique is used to eliminate scalar coupling artifacts via the combination of in-phase and quadrature images acquired at echo times differing by 1/2J with an echoplanar readout. The second approach employs a highly narrowband RF excitation pulse to image a single peak from the J-coupled doublet.

RESULTS

Simulations using a numerical Shepp-Logan phantom, in vitro experiments using thermally polarized [2-¹³ C]lactate, thermally and hyperpolarized ¹³ C-formate phantoms, and in vivo imaging of [2-¹³ C]lactate produced in rat brain following injection of hyperpolarized [2-¹³ C]pyruvate show artifact-free images and demonstrate potential utility of these methods.

CONCLUSION

The quadrature imaging and the narrowband excitation techniques resolve the J-coupling induced ghosting and blurring artifacts present with conventional MRI of J-coupled signals such as [2-¹³ C]lactate.