Metabolism of stromal and immune cells in health and disease

Review: Synovial Cell Metabolism and Chronic Inflammation in Rheumatoid Arthritis

Metabolomic studies of body fluids show that immune-mediated inflammatory diseases such as rheumatoid arthritis (RA) are associated with metabolic disruption. This is likely to reflect the increased bioenergetic and biosynthetic demands of sustained inflammation and changes in nutrient and oxygen availability in damaged tissue. The synovial membrane lining layer is the principal site of inflammation in RA. Here, the resident cells are fibroblast-like synoviocytes (FLS) and synovial tissue macrophages, which are transformed toward overproduction of enzymes that degrade cartilage and bone and cytokines that promote immune cell infiltration. Recent studies have shown metabolic changes in both FLS and macrophages from RA patients, and these may be therapeutically targetable. However, because the origins and subset-specific functions of synoviocytes are poorly understood, and the signaling modules that control metabolic deviation in RA synovial cells are yet to be explored, significant additional research is needed to translate these findings to clinical application. Furthermore, in many inflamed tissues, different cell types can forge metabolic collaborations through solute carriers in their membranes to meet a high demand for energy or biomolecules. Such relationships are likely to exist in the synovium and have not been studied. Finally, it is not yet known whether metabolic change is a consequence of disease or whether primary changes to cellular metabolism might underlie or contribute to the pathogenesis of early-stage disease. In this review article, we collate what is known about metabolism in synovial tissue cells and highlight future directions of research in this area.

Glucose transporters in cancer - from tumor cells to the tumor microenvironment

Solute carriers of the glucose transporter (GLUT) family mediate the first step for cellular glucose usage. The upregulation of GLUTs has been reported in numerous cancer types as a result of perturbation of gene expression or protein relocalization or stabilization. Because they enable to sustain the energy demand required by tumor cells for various biochemical programs, they are promising targets for the development of anticancer strategies. Recently, important biological insights have come from the fine crystal structure determination of several GLUTs; these advances will likely catalyze the development of new selective inhibitory compounds. Furthermore, deregulated glucose metabolism of nontumor cells in the tumor mass is beginning to be appreciated and could have major implications for our understanding of how glucose uptake by specific cell types influences the behavior of neighboring cells in the same microenvironment. In this review, we discuss some of the deregulation mechanisms of glucose transporters, their genetic and pharmacological targeting in cancer, and new functions they may have in nontumor cells of the tumor environment or beyond glucose uptake for glycolysis.

Comparative assessment of Graves' disease and main extrathyroidal manifestation, Graves' ophthalmopathy, by non-targeted metabolite profiling of blood and orbital tissue

Graves' disease (GD) is an autoimmune disorder that causes the overproduction of thyroid hormones and consequent cascade of systemic metabolism dysfunction. Moreover, Graves' ophthalmopathy (GO) is the main extrathyroidal manifestation of Graves' disease (GD). The goal of the study was to identify metabolic signatures in association with diagnostic biomarkers of GD without GO and GO, respectively. Ninety metabolites were profiled and analyzed based on a non-targeted primary metabolite profiling from plasma samples of 21 GD patients without GO, 26 subjects with GO, and 32 healthy subjects. Multivariate statistics showed a clear discrimination between healthy controls and disease group (R2Y = 0.518, Q2 = 0.478) and suggested a biomarker panel consisting of 10 metabolites. Among them, most of metabolites showed the positive association with the levels of thyrotropin receptor antibodies. With combination of proline and 1,5-anhydroglucitol, which were identified as GO-specific modulators, the re-constructed biomarker model greatly improved the statistical power and also facilitated simultaneous discrimination among healthy control, GO, and GD without GO groups (AUC = 0.845-0.935). Finally, the comparative analysis of tissue metabolite profiles from GO patients proposed putative metabolic linkage between orbital adipose/connective tissues and the biofluidic consequences, in which fumarate, proline, phenylalanine, and glycerol were coordinately altered with the blood metabolites.

The interplay between metabolic remodeling and immune regulation in glioblastoma

The fields of tumor metabolism and immune oncology have both independently received considerable attention over the last several years. The majority of research in tumor metabolism has largely focused on the Warburg effect and its resulting biologic consequences, including energy and macromolecule production. However, recent investigations have identified elegant, multifaceted strategies by which alterations in tumor metabolism can also contribute to a potent tolerogenic immune environment. One of the most notable is increased tryptophan metabolism through activation of indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO). However, this pathway represents one of numerous metabolic pathways that may modulate the immune system. For example, metabolites associated with aerobic glycolysis, adenosine, arginine, and prostaglandin metabolism have all been implicated in cancer-mediated immune tolerance and represent attractive therapeutic targets. In this review, we will provide an overview of the emerging interface between these 2 timely areas of cancer research and provide an overview of strategies currently being tested to target these next-generation metabolic immune checkpoints.

Macrophage MicroRNAs as Therapeutic Targets for Atherosclerosis, Metabolic Syndrome, and Cancer

Macrophages play a crucial role in the innate immune system and contribute to a broad spectrum of pathologies in chronic inflammatory diseases. MicroRNAs (miRNAs) have been demonstrated to play important roles in macrophage functions by regulating macrophage polarization, lipid metabolism and so on. Thus, miRNAs represent promising diagnostic and therapeutic targets in immune disorders. In this review, we will summarize the role of miRNAs in atherosclerosis, metabolic syndrome, and cancer by modulating macrophage phenotypes, which has been supported by in vivo evidence.

Biochemistry of proinflammatory macrophage activation

In the last decade, metabolism has been recognized as a major determinant of immunological processes. During an inflammatory response, macrophages undergo striking changes in their metabolism. This metabolic reprogramming is governed by a complex interplay between metabolic enzymes and metabolites of different pathways and represents the basis for proper macrophage function. It is now evident that these changes go far beyond the well-known Warburg effect and the perturbation of metabolic targets is being investigated as a means to treat infections and auto-immune diseases. In the present review, we will aim to provide an overview of the metabolic responses during proinflammatory macrophage activation and show how these changes modulate the immune response.

Whole Organ Tissue Vascularization: Engineering the Tree to Develop the Fruits

Tissue engineering aims to regenerate and recapitulate a tissue or organ that has lost its function. So far successful clinical translation has been limited to hollow organs in which rudimental vascularization can be achieved by inserting the graft into flaps of the omentum or muscle fascia. This technique used to stimulate vascularization of the graft takes advantage of angiogenesis from existing vascular networks. Vascularization of the engineered graft is a fundamental requirement in the process of engineering more complex organs, as it is crucial for the efficient delivery of nutrients and oxygen following in-vivo implantation. To achieve vascularization of the organ many different techniques have been investigated and exploited. The most promising results have been obtained by seeding endothelial cells directly into decellularized scaffolds, taking advantage of the channels remaining from the pre-existing vascular network. Currently, the main hurdle we need to overcome is achieving a fully functional vascular endothelium, stable over a long time period of time, which is engineered using a cell source that is clinically suitable and can generate, in vitro, a yield of cells suitable for the engineering of human sized organs. This review will give an overview of the approaches that have recently been investigated to address the issue of vascularization in the field of tissue engineering of whole organs, and will highlight the current caveats and hurdles that should be addressed in the future.

A peek into cancer-associated fibroblasts: origins, functions and translational impact

In malignant tumors, cancer cells adapt to grow within their host tissue. As a cancer progresses, an accompanying host stromal response evolves within and around the nascent tumor. Among the host stromal constituents associated with the tumor are cancer-associated fibroblasts, a highly abundant and heterogeneous population of cells of mesenchymal lineage. Although it is known that fibroblasts are present from the tumor's inception to the end-stage metastatic spread, their precise functional role in cancer is not fully understood. It has been suggested that cancer-associated fibroblasts play a key role in modulating the behavior of cancer cells, in part by promoting tumor growth, but evolving data also argue for their antitumor actions. Taken together, this suggests a putative bimodal function for cancer-associated fibroblasts in oncogenesis. As illustrated in this Review and its accompanying poster, cancer-associated fibroblasts are a dynamic component of the tumor microenvironment that orchestrates the interplay between the cancer cells and the host stromal response. Understanding the complexity of the relationship between cancer cells and cancer-associated fibroblasts could offer insights into the regulation of tumor progression and control of cancer.

Summary: Cancer-associated fibroblasts constitute a functionally heterogeneous mesenchymal cell population in the tumor microenvironment. This ‘At a glance’ article reviews their origin and their pro- and antitumor properties.

NRF2 regulates endothelial glycolysis and proliferation with miR-93 and mediates the effects of oxidized phospholipids on endothelial activation

Phospholipids, such as 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC), are the major components of cell membranes. Their exposure to reactive oxygen species creates oxidized phospholipids, which predispose to the development of chronic inflammatory diseases and metabolic disorders through endothelial activation and dysfunction. Although the effects of oxidized PAPC (oxPAPC) on endothelial cells have been previously studied, the underlying molecular mechanisms evoking biological responses remain largely unknown. Here, we investigated the molecular mechanisms of oxPAPC function with a special emphasis on NRF2-regulated microRNAs (miRNAs) in human umbilical vein endothelial cells (HUVECs) utilizing miRNA profiling, global run-on sequencing (GRO-seq), genome-wide NRF2 binding model, and RNA sequencing (RNA-seq) with miRNA overexpression and silencing. We report that the central regulators of endothelial activity, KLF2 for quiescence, PFKFB3 for glycolysis, and VEGFA, FOXO1 and MYC for growth and proliferation, are regulated by transcription factor NRF2 and the NRF2-regulated miR-106b∼25 cluster member, miR-93, in HUVECs. Mechanistically, oxPAPC was found to induce glycolysis and proliferation NRF2-dependently, and oxPAPC-dependent induction of the miR-106b∼25 cluster was mediated by NRF2. Additionally, several regulatory loops were established between NRF2, miR-93 and the essential regulators of healthy endothelium, collectively implying that NRF2 controls the switch between the quiescent and the proliferative endothelial states together with miR-93.

S100A4 promotes lung tumor development through β-catenin pathway-mediated autophagy inhibition

Autophagy has emerged as a critical pathway in tumor development. S100A4 plays important roles in tumor metastasis, but its role in regulating autophagy has not been well characterized. In this study, we found that S100A4 was significantly upregulated in lung adenocarcinoma tissues. Clinical investigation demonstrated that high expression level of S100A4 was associated with tumor size and advanced tumor grades of lung adenocarcinoma patients. Moreover, our results revealed that extracellular S100A4 or overexpression of S100A4 inhibited starvation-induced autophagy and promoted cell proliferation in lung cancer cells in vitro; whereas small interfering RNA (siRNA)-mediated suppression of S100A4 increased autophagy and reduced cell viability in both A549 and LLC cells. Additionally, S100A4 inhibited starvation-induced autophagy to promote tumor cell viability via the Wnt pathway. Increased expression of β-catenin consistently led to a decreased LC3-II protein abundance. Further, the inhibitory effect of S100A4 on autophagy and its promotion role in cell proliferation was abolished in A549 and LLC cells using the receptor for advanced glycation end products (RAGE)-specific inhibitor (FPS-ZM1). S100A4-deficient mice showed retarded tumor development. This effect was well correlated with increased expression of autophagy markers. Our findings demonstrate that S100A4 promotes lung tumor development through inhibiting autophagy in a β-catenin signaling and S100A4 receptor RAGE-dependent manner, which provides a novel mechanism of S100A4-associated promotion of tumor development.

A cleavage product of Polycystin-1 is a mitochondrial matrix protein that affects mitochondria morphology and function when heterologously expressed

Recent studies have reported intrinsic metabolic reprogramming in Pkd1 knock-out cells, implicating dysregulated cellular metabolism in the pathogenesis of polycystic kidney disease. However, the exact nature of the metabolic changes and their underlying cause remains controversial. We show herein that Pkd1 k o /ko renal epithelial cells have impaired fatty acid utilization, abnormal mitochondrial morphology and function, and that mitochondria in kidneys of ADPKD patients have morphological alterations. We further show that a C-terminal cleavage product of polycystin-1 (CTT) translocates to the mitochondria matrix and that expression of CTT in Pkd1 ko/ko cells rescues some of the mitochondrial phenotypes. Using Drosophila to model in vivo effects, we find that transgenic expression of mouse CTT results in decreased viability and exercise endurance but increased CO2 production, consistent with altered mitochondrial function. Our results suggest that PC1 may play a direct role in regulating mitochondrial function and cellular metabolism and provide a framework to understand how impaired mitochondrial function could be linked to the regulation of tubular diameter in both physiological and pathological conditions.

RIPK3 promotes kidney fibrosis via AKT-dependent ATP citrate lyase

Renal fibrosis is a common pathogenic response to injury in chronic kidney disease (CKD). The receptor-interacting protein kinase-3 (RIPK3), a regulator of necroptosis, has been implicated in disease pathogenesis. In mice subjected to unilateral ureteral obstruction-induced (UUO-induced) or adenine diet-induced (AD-induced) renal fibrosis, models of progressive kidney fibrosis, we demonstrate increased kidney expression of RIPK3. Mice genetically deficient in RIPK3 displayed decreased kidney fibrosis and improved kidney function relative to WT mice when challenged with UUO or AD. In contrast, mice genetically deficient in mixed-lineage kinase domain-like protein (MLKL), a downstream RIPK3 target, were not protected from UUO-induced kidney fibrosis. We demonstrate a pathway by which RIPK3 promotes fibrogenesis through the AKT-dependent activation of ATP citrate lyase (ACL). Genetic or chemical inhibition of RIPK3 suppressed the phosphorylation of AKT and ACL in response to TGF-β1 in fibroblasts. Inhibition of AKT or ACL suppressed TGF-β1-dependent extracellular matrix production and myofibroblast differentiation in fibroblasts. Pharmacological inhibition of ACL suppressed UUO-induced kidney fibrosis. RIPK3 expression was highly regulated in human CKD kidney. In conclusion, we identify a pathway by which RIPK3 promotes kidney fibrosis independently of MLKL-dependent necroptosis as a promising therapeutic target in CKD.

Mathematical modeling of cancer metabolism

Systemic approaches are needed and useful for the study of the very complex issue of cancer. Modeling has a central position in these systemic approaches. Metabolic reprogramming is nowadays acknowledged as an essential hallmark of cancer. Mathematical modeling could contribute to a better understanding of cancer metabolic reprogramming and to identify new potential ways of therapeutic intervention. Herein, I review several alternative approaches to metabolic modeling and their current and future impact in oncology.

Targeting metabolic abnormalities to reverse fibrosis in iatrogenic laryngotracheal stenosis

OBJECTIVE

Management of laryngotracheal stenosis (LTS) remains primarily surgical, with a critical need to identify targets for adjuvant therapy. Laryngotracheal stenosis scar fibroblasts exhibit a profibrotic phenotype with distinct metabolic shifts, including an increased glycolysis/oxidative phosphorylation ratio. This study examines the effects of the glutamine antagonist 6-diazo-5-oxo-l-norleucine (DON) on collagen production, gene expression, proliferation, and metabolism of human LTS-derived fibroblasts in vitro.

METHOD

Paired normal and scar-derived fibroblasts isolated from subglottic and proximal tracheal tissue in patients with iatrogenic laryngotracheal stenosis (iLTS) were cultured. Proliferation rate, gene expression, protein production, and cellular metabolism were assessed in two conditions: 1) fibroblast growth medium, and 2) fibroblast growth medium with 1 × 10-4 M DON.

RESULTS

DON treatment reduced cellular proliferation rate (n = 7, P =  0.0150). Expression of genes collagen 1 and collagen 3 both were reduced (n = 7, P =  0.0102, 0.0143, respectively). Soluble collagen production decreased (n = 7, P =  0.0056). As measured by the rate of extracellular acidification, glycolysis and glycolytic capacity decreased (n = 7, P =  0.0082, 0.0003, respectively). adenosine triphosphate (ATP) production and basal respiration decreased (n = 7, P = 0.0045, 0.0258, respectively), determined by measuring the cellular rate of oxygen consumption.

CONCLUSION

The glutamine antagonist DON reverses profibrotic changes by inhibiting both glycolysis and oxidative phosphorylation in iLTS scar fibroblasts. In contrast to untreated iLTS scar fibroblasts, collagen gene expression, protein production, metabolic rate, and proliferation were significantly reduced. These results suggest DON and/or its derivatives as strong candidates for adjuvant therapy in the management of iatrogenic laryngotracheal stenosis. Enzymes involved in glutamine metabolism inhibited by DON offer targets for future investigation.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:E59-E67, 2018.

Isolation, identification, and characterization of novel nanovesicles

Extracellular microvesicles (EVs) have been recognized for many potential clinical applications including biomarkers for disease diagnosis. In this study, we identified a major population of EVs by simply screening fluid samples with a nanosizer. Unlike other EVs, this extracellular nanovesicle (named HG-NV, HG-NV stands for HomoGenous nanovesicle as well as for Huang-Ge- nanovesicle) can be detected with a nanosizer with minimal in vitro manipulation and are much more homogenous in size (8–12 nm) than other EVs. A simple filtration platform is capable of separating HG-NVs from peripheral blood or cell culture supernatants. In comparison with corresponding exosome profiles, HG-NVs released from both mouse and human breast tumor cells are enriched with RNAs. Tumor derived HG-NVs are more potent in promoting tumor progression than exosomes. In summary, we identified a major subset of EVs as a previously unrecognized nanovesicle. Tumor cell derived HG-NVs promote tumor progression. Molecules predominantly present in breast tumor HG-NVs have been identified and characterized. This discovery may have implications in advancing both microvesicle biology research and clinical management including potential used as a biomarker.

Tissue-specific endothelial cells: a promising approach for augmentation of soft tissue repair in orthopedics

Biologics are playing an increasingly significant role in the practice of modern medicine and surgery in general and orthopedics in particular. Cell-based approaches are among the most important and widely used modalities in orthopedic biologics, with mesenchymal stem cells and other multi/pluripotent cells undergoing evaluation in numerous preclinical and clinical studies. On the other hand, fully differentiated endothelial cells (ECs) have been found to perform critical roles in homeostasis of visceral tissues through production of an adaptive panel of so-called "angiocrine factors." This newly discovered function of ECs renders them excellent candidates for novel approaches in cell-based biologics. Here, we present a review of the role of ECs and angiocrine factors in some visceral tissues, followed by an overview of current cell-based approaches and a discussion of the potential applications of ECs in soft tissue repair.

Glucose monitoring in living cells with single fluorescent protein-based sensors

Glucose is the main source of energy and carbon in organisms and plays a central role in metabolism and cellular homeostasis. However, the sensitive fluctuation of glucose in living cells is difficult to monitor. Thus, we developed a series of ratiometric, highly responsive, single fluorescent protein-based glucose sensors of wide dynamic range by combining a circularly permuted yellow fluorescent protein with a bacterial periplasmic glucose/galactose-binding protein. We used these sensors to monitor glucose transport in living Escherichia coli cells, and found that the cells take up glucose within 10 min to maintain physiological glucose levels, and observed the differences in glucose uptake and glucose metabolism between wild-type and Mlc knockout cells. These sensors can be specific and simple tools for glucose detection in vitro and non-invasive tools for real-time monitoring of glucose metabolism in vivo.

Glucose is the main source of energy and carbon in organisms and plays a central role in metabolism and cellular homeostasis.

A New Perspective on the Heterogeneity of Cancer Glycolysis

Tumors are dynamic metabolic systems which highly augmented metabolic fluxes and nutrient needs to support cellular proliferation and physiological function. For many years, a central hallmark of tumor metabolism has emphasized a uniformly elevated aerobic glycolysis as a critical feature of tumorigenecity. This led to extensive efforts of targeting glycolysis in human cancers. However, clinical attempts to target glycolysis and glucose metabolism have proven to be challenging. Recent advancements revealing a high degree of metabolic heterogeneity and plasticity embedded among various human cancers may paint a new picture of metabolic targeting for cancer therapies with a renewed interest in glucose metabolism. In this review, we will discuss diverse oncogenic and molecular alterations that drive distinct and heterogeneous glucose metabolism in cancers. We will also discuss a new perspective on how aberrantly altered glycolysis in response to oncogenic signaling is further influenced and remodeled by dynamic metabolic interaction with surrounding tumor-associated stromal cells.

Endothelial Rab7 GTPase mediates tumor growth and metastasis in lysosomal acid lipase-deficient mice

Tumors depend on their microenvironment for sustained growth, invasion, and metastasis. In this environment, endothelial cells (ECs) are an important stromal cell type interacting with malignant cells to facilitate tumor angiogenesis and cancer cell extravasation. Of note, lysosomal acid lipase (LAL) deficiency facilitates melanoma growth and metastasis. ECs from LAL-deficient (lal-/-) mice possess enhanced proliferation, migration, and permeability of inflammatory cells by activating the mammalian target of rapamycin (mTOR) pathway. Here we report that lal-/- ECs facilitated in vivo tumor angiogenesis, growth, and metastasis, largely by stimulating tumor cell proliferation, migration, adhesion, and transendothelial migration via increased expression of IL-6 and monocyte chemoattractant protein 1 (MCP-1). This prompted us to look for lysosomal proteins that are involved in lal-/- EC dysfunctions. We found that lal-/- ECs displayed increased expression of Rab7, a late endosome/lysosome-associated small GTPase. Moreover, Rab7 and mTOR were co-increased and co-localized to lysosomes and physically interacted in lal-/- ECs. Rab7 inhibition reversed lal-/- EC dysfunctions, including decreasing their enhanced migration and permeability of tumor-stimulatory myeloid cells, and suppressed EC-mediated stimulation of in vitro tumor cell transmigration, proliferation, and migration and in vivo tumor growth and metastasis. Finally, Rab7 inhibition reduced overproduction of reactive oxygen species and increased IL-6 and MCP-1 secretion in lal-/- ECs. Our results indicate that metabolic reprogramming resulting from LAL deficiency enhances the ability of ECs to stimulate tumor cell proliferation and metastasis through stimulation of lysosome-anchored Rab7 activity.

Organoiridium Photosensitizers Induce Specific Oxidative Attack on Proteins within Cancer Cells

Strongly luminescent iridium(III) complexes, [Ir(C,N)2 (S,S)]+ (1) and [Ir(C,N)2 (O,O)] (2), containing C,N (phenylquinoline), O,O (diketonate), or S,S (dithione) chelating ligands, have been characterized by X-ray crystallography and DFT calculations. Their long phosphorescence lifetimes in living cancer cells give rise to high quantum yields for the generation of 1 O2 , with large 2-photon absorption cross-sections. 2 is nontoxic to cells, but potently cytotoxic to cancer cells upon brief irradiation with low doses of visible light, and potent at sub-micromolar doses towards 3D multicellular tumor spheroids with 2-photon red light. Photoactivation causes oxidative damage to specific histidine residues in the key proteins in aldose reductase and heat-shock protein-70 within living cancer cells. The oxidative stress induced by iridium photosensitizers during photoactivation can increase the levels of enzymes involved in the glycolytic pathway.

Exploring Metabolic Configurations of Single Cells within Complex Tissue Microenvironments

Over the past years, plenty of evidence has emerged illustrating how metabolism supports many aspects of cellular function and how metabolic reprogramming can drive cell differentiation and fate. Here, we present a method to assess the metabolic configuration of single cells within their native tissue microenvironment via the visualization and quantification of multiple enzymatic activities measured at saturating substrate conditions combined with subsequent cell type identification. After careful validation of the approach and to demonstrate its potential, we assessed the intracellular metabolic configuration of different human immune cell populations in healthy and tumor colon tissue. Additionally, we analyzed the intercellular metabolic relationship between cancer cells and cancer-associated fibroblasts in a breast cancer tissue array. This study demonstrates that the determination of metabolic configurations in single cells could be a powerful complementary tool for every researcher interested to study metabolic networks in situ.

Functional coupling of human pancreatic islets and liver spheroids on-a-chip: Towards a novel human ex vivo type 2 diabetes model

Human in vitro physiological models studying disease and drug treatment effects are urgently needed as more relevant tools to identify new drug targets and therapies. We have developed a human microfluidic two-organ-chip model to study pancreatic islet–liver cross-talk based on insulin and glucose regulation. We have established a robust co-culture of human pancreatic islet microtissues and liver spheroids maintaining functional responses up to 15 days in an insulin-free medium. Functional coupling, demonstrated by insulin released from the islet microtissues in response to a glucose load applied in glucose tolerance tests on different days, promoted glucose uptake by the liver spheroids. Co-cultures maintained postprandial glucose concentrations in the circulation whereas glucose levels remained elevated in both single cultures. Thus, insulin secreted into the circulation stimulated glucose uptake by the liver spheroids, while the latter, in the absence of insulin, did not consume glucose as efficiently. As the glucose concentration fell, insulin secretion subsided, demonstrating a functional feedback loop between the liver and the insulin-secreting islet microtissues. Finally, inter-laboratory validation verified robustness and reproducibility. Further development of this model using tools inducing impaired glucose regulation should provide a unique in vitro system emulating human type 2 diabetes mellitus.

The gestational power of mast cells in the injured tissue

The inflammatory response expressed after wound healing would be the recapitulation of systemic extra-embryonic functions, which would focus on the interstitium of the injured tissue. In the injured tissue, mast cells, provided for a great functional heterogeneity, could play the leading role in the re-expression of extra-embryonic functions, i.e., coelomic-amniotic and trophoblastic-vitelline. Moreover, mast cells would favor the production of a gastrulation-like process, which in certain tissues and organs would induce the regeneration of the injured tissue. Therefore, the engraftment of mesenchymal stem cells and mast cells, both with an extra-embryonic regenerative phenotype, would achieve a blastema, from the repaired and regenerated injured tissue, rather than by fibrosis, which is commonly made through wound-healing.

Tumor microenvironment heterogeneity: challenges and opportunities

The tumor microenvironment (TME) has been recognized as an integral component of malignancies in breast and prostate tissues, contributing in confounding ways to tumor progression, metastasis, therapy resistance and disease recurrence. Major components of the TME are immune cells, fibroblasts, pericytes, endothelial cells, mesenchymal stroma/stem cells (MSCs), and extracellular matrix (ECM) components. Herein, we discuss the molecular and cellular heterogeneity within the TME and how this presents unique challenges and opportunities for treating breast and prostate cancers.

Foundations of Immunometabolism and Implications for Metabolic Health and Disease

Highly ordered interactions between immune and metabolic responses are evolutionarily conserved and paramount for tissue and organismal health. Disruption of these interactions underlies the emergence of many pathologies, particularly chronic non-communicable diseases such as obesity and diabetes. Here, we examine decades of research identifying the complex immunometabolic signaling networks and the cellular and molecular events that occur in the setting of altered nutrient and energy exposures and offer a historical perspective. Furthermore, we describe recent advances such as the discovery that a broad complement of immune cells play a role in immunometabolism and the emerging evidence that nutrients and metabolites modulate inflammatory pathways. Lastly, we discuss how this work may eventually lead to tangible therapeutic advancements to promote health.

Sugar or Fat?-Metabolic Requirements for Immunity to Viral Infections

The realization that an intricate link exists between the metabolic state of immune cells and the nature of the elicited immune responses has brought a dramatic evolution to the field of immunology. We will focus on how metabolic reprogramming through the use of glycolysis and fatty-acid oxidation (sugar or fat) regulates the capacity of immune cells to mount robust and effective immune responses. We will also discuss how fine-tuning sugar and fat metabolism may be exploited as a novel immunotherapeutic strategy to fight viral infections or improve vaccine efficacy.

The brain and immune system prompt energy shortage in chronic inflammation and ageing

Sequelae frequently seen in patients with chronic inflammatory diseases, such as fatigue, depressed mood, sleep alterations, loss of appetite, muscle wasting, cachectic obesity, bone loss and hypertension, can be the result of energy shortages caused by an overactive immune system. These sequelae can also be found in patients with chronic inflammatory diseases that are in remission and in ageing individuals, despite the immune system being less active in these situations. This Perspectives article proposes a new way of understanding situations of chronic inflammation (such as rheumatic diseases) and ageing based on the principles of evolutionary medicine, energy regulation and neuroendocrine-immune crosstalk. A conceptual framework is provided to enable physicians and scientists to better understand the signs and symptoms of chronic inflammatory diseases and long-term disease consequences resulting from physical and mental inactivity.

Endothelial adenosine A2a receptor-mediated glycolysis is essential for pathological retinal angiogenesis

Adenosine/adenosine receptor-mediated signaling has been implicated in the development of various ischemic diseases, including ischemic retinopathies. Here, we show that the adenosine A2a receptor (ADORA2A) promotes hypoxia-inducible transcription factor-1 (HIF-1)-dependent endothelial cell glycolysis, which is crucial for pathological angiogenesis in proliferative retinopathies. Adora2a expression is markedly increased in the retina of mice with oxygen-induced retinopathy (OIR). Endothelial cell-specific, but not macrophage-specific Adora2a deletion decreases key glycolytic enzymes and reduces pathological neovascularization in the OIR mice. In human primary retinal microvascular endothelial cells, hypoxia induces the expression of ADORA2A by activating HIF-2α. ADORA2A knockdown decreases hypoxia-induced glycolytic enzyme expression, glycolytic flux, and endothelial cell proliferation, sprouting and tubule formation. Mechanistically, ADORA2A activation promotes the transcriptional induction of glycolytic enzymes via ERK- and Akt-dependent translational activation of HIF-1α protein. Taken together, these findings advance translation of ADORA2A as a therapeutic target in the treatment of proliferative retinopathies and other diseases dependent on pathological angiogenesis.Pathological angiogenesis in the retina is a major cause of blindness. Here the authors show that adenosine receptor A2A drives pathological angiogenesis in the oxygen-induced retinopathy mouse model by promoting glycolysis in endothelial cells via the ERK/Akt/HIF-1α pathway, thereby suggesting new therapeutic targets for disease treatment.

YAP/TAZ regulates sprouting angiogenesis and vascular barrier maturation

Angiogenesis is a multistep process that requires coordinated migration, proliferation, and junction formation of vascular endothelial cells (ECs) to form new vessel branches in response to growth stimuli. Major intracellular signaling pathways that regulate angiogenesis have been well elucidated, but key transcriptional regulators that mediate these signaling pathways and control EC behaviors are only beginning to be understood. Here, we show that YAP/TAZ, a transcriptional coactivator that acts as an end effector of Hippo signaling, is critical for sprouting angiogenesis and vascular barrier formation and maturation. In mice, endothelial-specific deletion of Yap/Taz led to blunted-end, aneurysm-like tip ECs with fewer and dysmorphic filopodia at the vascular front, a hyper-pruned vascular network, reduced and disarranged distributions of tight and adherens junction proteins, disrupted barrier integrity, subsequent hemorrhage in growing retina and brain vessels, and reduced pathological choroidal neovascularization. Mechanistically, YAP/TAZ activates actin cytoskeleton remodeling, an important component of filopodia formation and junction assembly. Moreover, YAP/TAZ coordinates EC proliferation and metabolic activity by upregulating MYC signaling. Overall, these results show that YAP/TAZ plays multifaceted roles for EC behaviors, proliferation, junction assembly, and metabolism in sprouting angiogenesis and barrier formation and maturation and could be a potential therapeutic target for treating neovascular diseases.

Cellular metabolism of tumor-associated macrophages - functional impact and consequences

Macrophages are innate immune cells that play a role not only in host defense against infections, but also in the pathophysiology of autoimmune and autoinflammatory disorders, as well as cancer. An important feature of macrophages is their high plasticity, with high ability to adapt to environmental changes by adjusting their cellular metabolism and immunological phenotype. Macrophages are one of the most abundant innate immune cells within the tumor microenvironment that have been associated with tumor growth, metastasis, angiogenesis and poor prognosis. In the context of cancer, however, so far little is known about metabolic changes in macrophages, which have been shown to determine functional fate of the cells in other diseases. Here, we review the current knowledge regarding the cellular metabolism of tumor-associated macrophages (TAMs) and discuss its implications for cell function. Understanding the regulation of the cellular metabolism of TAMs may reveal novel therapeutic targets for treatment of malignancies.

Similarities in the Metabolic Reprogramming of Immune System and Endothelium

Cellular metabolism has been known for its role in bioenergetics. In recent years, much light has been shed on the reprogrammable cellular metabolism underlying many vital cellular processes, such as cell activation, proliferation, and differentiation. Metabolic reprogramming in immune and endothelial cells (ECs) is being studied extensively. These cell compartments are implicated in inflammation and pathogenesis of many diseases but their similarities in metabolic reprogramming have not been analyzed in detail. One of the most notable metabolic reprogramming is the Warburg-like effect, famously described as one of the hallmarks of cancer cells. Immune cells and ECs can display this phenotype that is characterized by a metabolic switch favoring glycolysis over oxidative phosphorylation (OXPHOS) in aerobic conditions. Though energy-inefficient, aerobic glycolysis confers many benefits to the respiring cells ranging from higher rate of adenosine triphosphate production to maintaining redox homeostasis. Chemical and biological regulators either promote or perturb this effect. In this review, nitric oxide, hypoxia-inducible factor, and adenosine monophosphate-activated protein kinase have been discussed for their common involvement in metabolic reprogramming of both systems. From in vitro and animal studies, various discrepancies exist regarding the effects of those regulators on metabolic switch. However, it is generally accepted that glycolysis favors inflammatory reactions while OXPHOS favors anti-inflammatory processes. The reasons for such observation are currently subject of intense studies and not completely understood. Finally, metabolic reprogramming in immune cells and ECs does not limit to the physiological state in health but can also be observed in pathological states, such as atherosclerosis and cancer. These new insights provide us with a better understanding of the similarities in metabolic reprogramming across a number of cell types, which could pave the way for future research and possible metabolic-based therapeutics.

To Eat and to Be Eaten: Mutual Metabolic Adaptations of Immune Cells and Intracellular Bacterial Pathogens upon Infection

Intracellular bacterial pathogens (IBPs) invade and replicate in different cell types including immune cells, in particular of the innate immune system (IIS) during infection in the acute phase. However, immune cells primarily function as essential players in the highly effective and integrated host defense systems comprising the IIS and the adaptive immune system (AIS), which cooperatively protect the host against invading microbes including IBPs. As countermeasures, the bacterial pathogens (and in particular the IBPs) have developed strategies to evade or reprogram the IIS at various steps. The intracellular replication capacity and the anti-immune defense responses of the IBP's as well as the specific antimicrobial responses of the immune cells of the innate and the AIS depend on specific metabolic programs of the IBPs and their host cells. The metabolic programs of the immune cells supporting or counteracting replication of the IBPs appear to be mutually exclusive. Indeed, recent studies show that upon interaction of naïve, metabolically quiescent immune cells with IBPs, different metabolic activation processes occur which may result in the provision of a survival and replication niche for the pathogen or its eradication. It is therefore likely that within a possible host cell population subsets exist that are metabolically programmed for pro- or anti-microbial conditions. These metabolic programs may be triggered by the interactions between different bacterial agonistic components and host cell receptors. In this review, we summarize the current status in the field and discuss metabolic adaptation processes within immune cells of the IIS and the IBPs that support or restrict the intracellular replication of the pathogens.

Critical Role of Glucose Metabolism in Rheumatoid Arthritis Fibroblast-like Synoviocytes

OBJECTIVE

Up-regulation of glucose metabolism has been implicated not only in tumor cell growth but also in immune cells upon activation. However, little is known about the metabolite profile in rheumatoid arthritis (RA), particularly in fibroblast-like synoviocytes (FLS). This study was undertaken to evaluate whether changes in glucose metabolism in RA FLS could play a role in inflammation and joint damage.

METHODS

Synovium and FLS were obtained from patients with RA and patients with osteoarthritis (OA). The rate of glycolysis after stimulation of FLS with lipopolysaccharide and platelet-derived growth factor BB was measured using glycolysis stress test technology. FLS function was evaluated using a glycolysis inhibitor, 2-deoxy-d-glucose (2-DG). After stimulation of the FLS, a migration scratch assay, MTT assay, and enzyme-linked immunosorbent assay were performed to measure the effect of 2-DG on FLS migration, viability of the FLS, and cytokine secretion, respectively. IRDye 800CW 2-DG was used to assess glucose uptake in the arthritic joints and stromal cells of mice after K/BxN mouse serum transfer. The mice were injected daily, intraperitoneally, with 3-bromopyruvate (BrPa; 5 mg/kg) to assess the effect of inhibition of glycolysis in vivo.

RESULTS

Compared to human OA FLS, the balance between glycolysis and oxidative phosphorylation was shifted toward glycolysis in RA FLS. Glucose transporter 1 (GLUT1) messenger RNA (mRNA) expression correlated with baseline functions of the RA FLS. Glucose deprivation or incubation of the FLS with glycolytic inhibitors impaired cytokine secretion and decreased the rate of proliferation and migration of the cells. In a mouse model of inflammatory arthritis, GLUT1 mRNA expression in the synovial lining cells was observed, and increased levels of glucose uptake and glycolytic gene expression were detected in the stromal compartment of the arthritic mouse joints. Inhibition of glycolysis by BrPa, administered in vivo, significantly decreased the severity of arthritis in this mouse model.

CONCLUSION

Targeting metabolic pathways is a novel approach to understanding the mechanisms of disease. Inhibition of glycolysis may directly modulate synoviocyte-mediated inflammatory functions and could be an effective treatment strategy for arthritis.

Fuelling the mechanisms of asthma: Increased fatty acid oxidation in inflammatory immune cells may represent a novel therapeutic target

BACKGROUND

Increasing evidence has shown the close link between energy metabolism and the differentiation, function, and longevity of immune cells. Chronic inflammatory conditions such as parasitic infections and cancer trigger a metabolic reprogramming from the preferential use of glucose to the up-regulation of fatty acid oxidation (FAO) in myeloid cells, including macrophages and granulocytic and monocytic myeloid-derived suppressor cells. Asthma is a chronic inflammatory condition where macrophages, eosinophils, and polymorphonuclear cells play an important role in its pathophysiology.

OBJECTIVE

We tested whether FAO might play a role in the development of asthma-like traits and whether the inhibition of this metabolic pathway could represent a novel therapeutic approach.

METHODS

OVA- and house dust mite (HDM)-induced murine asthma models were used in this study.

RESULTS

Key FAO enzymes were significantly increased in the bronchial epithelium and inflammatory immune cells infiltrating the respiratory epithelium of mice exposed to OVA or HDM. Pharmacologic inhibition of FAO significantly decreased allergen-induced airway hyperresponsiveness, decreased the number of inflammatory cells, and reduced the production of cytokines and chemokines associated with asthma.

CONCLUSIONS AND CLINICAL RELEVANCE

These novel observations suggest that allergic airway inflammation increases FAO in inflammatory cells to support the production of cytokines, chemokines, and other factors important in the development of asthma. Inhibition of FAO by re-purposing existing drugs approved for the treatment of heart disease may provide a novel therapeutic approach for the treatment of asthma.

Kinetic analysis, size profiling, and bioenergetic association of DNA released by selected cell lines in vitro

Although circulating DNA (cirDNA) analysis shows great promise as a screening tool for a wide range of pathologies, numerous stumbling blocks hinder the rapid translation of research to clinical practice. This is related directly to the inherent complexity of the in vivo setting, wherein the influence of complex systems of interconnected cellular responses and putative DNA sources creates a seemingly arbitrary representation of the quantitative and qualitative properties of the cirDNA in the blood of any individual. Therefore, to evaluate the potential of in vitro cell cultures to circumvent the difficulties encountered in in vivo investigations, the purpose of this work was to elucidate the characteristics of the DNA released [cell-free DNA (cfDNA)] by eight different cell lines. This revealed three different forms of cfDNA release patterns and the presence of nucleosomal fragments as well as actively released forms of DNA, which are not only consistently observed in every tested cell line, but also in plasma samples. Correlations between cfDNA release and cellular origin, growth rate, and cancer status were also investigated by screening and comparing bioenergetics flux parameters. These results show statistically significant correlations between cfDNA levels and glycolysis, while no correlations between cfDNA levels and oxidative phosphorylation were observed. Furthermore, several correlations between growth rate, cancer status, and dependency on aerobic glycolysis were observed. Cell cultures can, therefore, successfully serve as closed-circuit models to either replace or be used in conjunction with biofluid samples, which will enable sharper focus on specific cell types or DNA origins.

Endothelial cell metabolism in health and disease: impact of hypoxia

In contrast to the general belief, endothelial cell (EC) metabolism has recently been identified as a driver rather than a bystander effect of angiogenesis in health and disease. Indeed, different EC subtypes present with distinct metabolic properties, which determine their function in angiogenesis upon growth factor stimulation. One of the main stimulators of angiogenesis is hypoxia, frequently observed in disease settings such as cancer and atherosclerosis. It has long been established that hypoxic signalling and metabolism changes are highly interlinked. In this review, we will provide an overview of the literature and recent findings on hypoxia-driven EC function and metabolism in health and disease. We summarize evidence on metabolic crosstalk between different hypoxic cell types with ECs and suggest new metabolic targets.

Macrophage NOS2 in Tumor Leukocytes

SIGNIFICANCE

Leukocytes and especially macrophages are a major cellular constituent of the tumor mass. The tumor microenvironment not only determines their activity but in turn these cells also contribute to tumor initiation and progression. Recent Advances: Proinflammatory stimulated macrophages upregulate inducible nitric oxide synthase (NOS2) and produce high steady-state NO concentrations. NO provokes tumor cell death by initiating apoptosis and/or necrosis. Mechanisms may comprise p53 accumulation, immunestimulatory activities, and an increased efficacy of chemo- and/or radiotherapy. However, the potential cytotoxic activity of macrophages often is compromised in the tumor microenvironment and instead a protumor activity of macrophages dominates. Contributing factors are signals generated by viable and dying tumor cells, attraction and activation of myeloid-derived suppressor cells, and hypoxia. Limited oxygen availability not only attenuates NOS2 activity but also causes accumulation of hypoxia-inducible factors 1 and 2 (HIF-1/HIF-2). Activation of the HIF system is tightly linked to NO formation and affects the expression of macrophage phenotype markers that in turn add to tumor progression.

CRITICAL ISSUES

To make use of the cytotoxic arsenal of activated macrophages directed against tumor cells, it will be critical to understand how, when, and where these innate immune responses are blocked and whether it will be possible to reinstall their full capacity to kill tumor cells.

FUTURE DIRECTIONS

Low-dose irradiation or proinflammatory activation of macrophages in the tumor microenvironment may open options to boost NOS2 expression and activity and to initiate immunestimulatory features of NO that may help to restrict tumor growth. Antioxid. Redox Signal. 26, 1023-1043.

Effects of Notch signalling pathway on the relationship between vascular endothelial dysfunction and endothelial stromal transformation in atherosclerosis

At present, with the improvement of living standards and population aging, the incidence of cardiovascular and cerebrovascular disease is on the rise and has been a serious threat to human health. Statistics show that the current death caused by cardiovascular and cerebrovascular disease has become the first cause of death has been increasing year by year. Therefore, studies on coronary heart disease and atherosclerosis (AS) have become a hot topic in clinical and basic research. In this study, the question of the effect of Notch signalling pathway on the relationship between endothelial dysfunction and endothelial stromal transformation in AS was studied in depth. Based on our results, we drew conclusions as follows. First, the Notch signalling pathway was activated in the atherosclerotic model; secondly, the Notch signalling pathway was demonstrated to enhance AS by promoting vascular endothelial dysfunction; thirdly, it was demonstrated that the Notch signalling pathway was mediated by promoting endothelial and to enhance AS; finally, we confirmed the endothelial function through the Notch signalling pathway to affect the transformation of endothelial stroma to achieve synergistic AS effect. The results of this study have a good guiding significance for the important role of Notch signalling in AS and indicate the ability to influence endothelial function and endothelial stromal transformation by intervening Notch signalling pathway and can affect the relationship between them, and thus eventually achieve the treatment of AS.

Fibroblast-like synoviocyte metabolism in the pathogenesis of rheumatoid arthritis

An increasing number of studies show how changes in intracellular metabolic pathways alter tumor and immune cell function. However, little information about metabolic changes in other cell types, including synovial fibroblasts, is available. In rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) are the most common cell type at the pannus–cartilage junction and contribute to joint destruction through their production of cytokines, chemokines, and matrix-degrading molecules and by migrating and invading joint cartilage. In this review, we show that these cells differ from healthy synovial fibroblasts, not only in their marker expression, proto-oncogene expression, or their epigenetic changes, but also in their intracellular metabolism. These metabolic changes must occur due to the stressful microenvironment of inflamed tissues, where concentrations of crucial nutrients such as glucose, glutamine, and oxygen are spatially and temporally heterogeneous. In addition, these metabolic changes will increase metabolite exchange between fibroblast and other synovial cells, which can potentially be activated. Glucose and phospholipid metabolism as well as bioactive lipids, including sphingosine-1-phosphate and lysophosphatidic acid, among others, are involved in FLS activation. These metabolic changes likely contribute to FLS involvement in aspects of immune response initiation or abnormal immune responses and strongly contribute to joint destruction.

Integrated functions of membrane-type 1 matrix metalloproteinase in regulating cancer malignancy: Beyond a proteinase

Membrane‐type 1 matrix metalloproteinase (MT1‐MMP) is expressed in different types of invasive and proliferative cells, including cancer cells and stromal cells. MT1‐MMP cleaves extracellular matrix proteins, membrane proteins and other pericellular proteins, thereby changing the cellular microenvironment and regulating signal activation. Critical roles of protease activity in cancer cell proliferation, invasion and metastasis have been demonstrated by many groups. MT1‐MMP also has a non‐protease activity in that it inhibits the oxygen‐dependent suppression of hypoxia‐inducible factors (HIFs) via Munc18‐1‐interacting protein 3 (Mint3) and thereby enhances the expression of HIF target genes. Elevated HIF activity in MT1‐MMP‐expressing cancer cells is a fundamental mechanism underlying the Warburg effect, a well‐known phenomenon where malignant cancer cells exhibit a higher rate of glucose metabolism. Because specific intervention of HIF activation by MT1‐MMP suppresses tumor formation by cancer cells in mice, both the proteolytic and non‐proteolytic activities of MT1‐MMP are important for tumor malignancy and function in an integrated manner. In this review, we summarize recent findings relating to how MT1‐MMP activates HIF and its effects on cancer cells and stromal cells.

Progress in tumor-associated macrophage (TAM)-targeted therapeutics

As an essential innate immune population for maintaining body homeostasis and warding off foreign pathogens, macrophages display high plasticity and perform diverse supportive functions specialized to different tissue compartments. Consequently, aberrance in macrophage functions contributes substantially to progression of several diseases including cancer, fibrosis, and diabetes. In the context of cancer, tumor-associated macrophages (TAMs) in tumor microenvironment (TME) typically promote cancer cell proliferation, immunosuppression, and angiogenesis in support of tumor growth and metastasis. Oftentimes, the abundance of TAMs in tumor is correlated with poor disease prognosis. Hence, significant attention has been drawn towards development of cancer immunotherapies targeting these TAMs; either depleting them from tumor, blocking their pro-tumoral functions, or restoring their immunostimulatory/tumoricidal properties. This review aims to introduce readers to various aspects in development and evaluation of TAM-targeted therapeutics in pre-clinical and clinical stages.

Alpha-Ketoglutarate Curbs Differentiation and Induces Cell Death in Mesenchymal Stromal Precursors with Mitochondrial Dysfunction

Increased concentrations of reactive oxygen species (ROS) originating from dysfunctional mitochondria contribute to diverse aging-related degenerative disorders. But so far little is known about the impact of distinct ROS on metabolism and fate of stromal precursor cells. Here, we demonstrate that an increase in superoxide anion radicals due to superoxide dismutase 2 (Sod2) deficiency in stromal precursor cells suppress osteogenic and adipogenic differentiation through fundamental changes in the global metabolite landscape. Our data identify impairment of the pyruvate and l-glutamine metabolism causing toxic accumulation of alpha-ketoglutarate in the Sod2-deficient and intrinsically aged stromal precursor cells as a major cause for their reduced lineage differentiation. Alpha-ketoglutarate accumulation led to enhanced nucleocytoplasmic vacuolation and chromatin condensation-mediated cell death in Sod2-deficient stromal precursor cells as a consequence of DNA damage, Hif-1α instability, and reduced histone H3 (Lys27) acetylation. These findings hold promise for prevention and treatment of mitochondrial disorders commonly associated with aged individuals. Stem Cells 2017;35:1704-1718.

The vicious circle of hypometabolism in neurodegenerative diseases: Ways and mechanisms of metabolic correction

Hypometabolism, characterized by decreased brain glucose consumption, is a common feature of many neurodegenerative diseases. Initial hypometabolic brain state, created by characteristic risk factors, may predispose the brain to acquired epilepsy and sporadic Alzheimer's and Parkinson's diseases, which are the focus of this review. Analysis of available data suggests that deficient glucose metabolism is likely a primary initiating factor for these diseases, and that resulting neuronal dysfunction further promotes the metabolic imbalance, establishing an effective positive feedback loop and a downward spiral of disease progression. Therefore, metabolic correction leading to the normalization of abnormalities in glucose metabolism may be an efficient tool to treat the neurological disorders by counteracting their primary pathological mechanisms. Published and preliminary experimental results on this approach for treating Alzheimer's disease and epilepsy models support the efficacy of metabolic correction, confirming the highly promising nature of the strategy. © 2017 Wiley Periodicals, Inc.

Reenergizing T cell anti-tumor immunity by harnessing immunometabolic checkpoints and machineries

T cells patrol our bodies preventing pathogenic infections and malignant cell outgrowth. However, T cells must be properly controlled because aberrant or persistent T cell responses can damage tissues and contribute to autoimmune diseases and other chronic inflammatory diseases including metabolic syndrome. One regulatory mechanism utilized in immune cells is immunometabolic regulation, which ensures immune cells properly respond to systemic and peripheral metabolic cues. Recent work has suggested that deregulated metabolism in tumor cells creates a microenvironmental barrier for mounting effective anti-tumor immune responses. Here, we discuss how tumor cells evade immunosurveillance by modulating metabolic checkpoints in immune cells and discuss how memory T cells could provide effective anti-tumor responses by sustaining metabolic fitness and longevity.

Deciphering the mechanism of Huang-Lian-Jie-Du-Decoction on the treatment of sepsis by formula decomposition and metabolomics: Enhancement of cholinergic pathways and inhibition of HMGB-1/TLR4/NF-κB signaling

Sepsis is the major cause of morbidity and mortality in surgical patients. Huang-Lian-Jie-Du-Decoction (HLJDD), a well-known Chinese herb formula, has long been used for the treatment of sepsis. In this investigation, by leaving one herb out each time, the four component herbs of HLJDD were reformulated to four HLJDD variants Form1-4, corresponding to the removal of Phellodendri Chinensis Cortex, Scutellariae Radix, Gardeniae Fructu and Coptidis Rhizoma, respectively. Metabolomics approach combined with histological inspection, biochemical measurement and molecular biology was used to investigate the treatment effects of HLJDD and its four variants on cecal ligation and puncture (CLP) model of sepsis, which were compared to decipher the formulating principles of HLJDD. Our results showed that HLJDD exhibit the strongest therapeutic effects in the CLP models as compared with the four variants, which could be ascribed to its most significant enhancement of cholinergic anti-inflammatory pathway and inhibition of HMGB-1/TLR4/NF-κB signaling pathway. Most of all, metabolites changed specifically between groups of HLJDD and its four variants were related with the exceptional treatment effects of HLJDD.

Glutaminase 1 plays a key role in the cell growth of fibroblast-like synoviocytes in rheumatoid arthritis

Background

The recent findings of cancer-specific metabolic changes, including increased glucose and glutamine consumption, have provided new therapeutic targets for consideration. Fibroblast-like synoviocytes (FLS) from rheumatoid arthritis (RA) patients exhibit several tumor cell-like characteristics; however, the role of glucose and glutamine metabolism in the aberrant proliferation of these cells is unclear. Here, we evaluated the role of these metabolic pathways in RA-FLS proliferation and in autoimmune arthritis in SKG mice.

Methods

The expression of glycolysis- or glutaminolysis-related enzymes was evaluated by real-time polymerase chain reaction (PCR) and Western blotting, and the intracellular metabolites were evaluated by metabolomic analyses. The effects of glucose or glutamine on RA-FLS cell growth were investigated using glucose- or glutamine-free medium. Glutaminase (GLS)1 small interfering RNA (siRNA) and the GLS1 inhibitor compound 968 were used to inhibit GLS1 in RA-FLS, and compound 968 was used to study the effect of GLS1 inhibition in zymosan A-injected SKG mice.

Results

GLS1 expression was increased in RA-FLS, and metabolomic analyses revealed that glutamine metabolism was increased in RA-FLS. RA-FLS proliferation was reduced under glutamine-deprived, but not glucose-deprived, conditions. Cell growth of RA-FLS was inhibited by GLS1 siRNA transfection or GLS1 inhibitor treatment. Treating RA-FLS with either interleukin-17 or platelet-derived growth factor resulted in increased GLS1 levels. Compound 968 ameliorated the autoimmune arthritis and decreased the number of Ki-67-positive synovial cells in SKG mice.

Conclusions

Our results suggested that glutamine metabolism is involved in the pathogenesis of RA and that GLS1 plays an important role in regulating RA-FLS proliferation, and may be a novel therapeutic target for RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1283-3) contains supplementary material, which is available to authorized users.