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Neuroinflammation and dysregulated energy metabolism are linked to motor neuron degeneration in amyotrophic lateral sclerosis (ALS). The egl-9 family hypoxia-inducible factor (EGLN) enzymes, also known as prolyl hydroxylase domain (PHD) enzymes, are metabolic sensors regulating cellular inflammation and metabolism. Using an oligonucleotide-based and a genetic approach, we showed that the downregulation of Egln2 protected motor neurons and mitigated the ALS phenotype in two zebrafish models and a mouse model of ALS. Single-nucleus RNA sequencing of the murine spinal cord revealed that the loss of EGLN2 induced an astrocyte-specific downregulation of interferon-stimulated genes, mediated via the stimulator of interferon genes (STING) protein. In addition, we found that the genetic deletion of EGLN2 restored this interferon response in patient induced pluripotent stem cell (iPSC)-derived astrocytes, confirming the link between EGLN2 and astrocytic interferon signaling. In conclusion, we identified EGLN2 as a motor neuron protective target normalizing the astrocytic interferon-dependent inflammatory axis in vivo , as well as in patient-derived cells. [Display omitted] • Egln2 knockdown rescues motor axonopathy in both C9- and SOD1-ALS zebrafish • Egln2 deletion mitigates ALS phenotypes in SOD1-ALS mice and prolongs survival • EGLN2 deletion normalizes STING-induced interferon response in ALS astrocytes Germeys et al. identify EGLN2 as an ALS target that, when downregulated, protects motor neurons and mitigates the ALS phenotype in ALS zebrafish and mice. Using snRNA-seq and CRISPR-Cas9-edited patient iPSCs, they show that the downregulation of EGLN2 normalizes the STING-induced astrocytic interferon response in vivo and in patient-derived cells. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2005.12.023 Byline: Carmen Ruiz de Almodovar (1), Aernout Luttun (1), Peter Carmeliet (1) Abstract: In this issue of Cell, examine the role of hematopoietic cells in the formation of new blood vessels. They show that organ-specific expression of vascular endothelial growth factor (VEGF) is sufficient to mobilize and recruit hematopoietic cells from the bone marrow to the blood, but retention of the proangiogenic subpopulation of hematopoietic cells in peripheral organs requires an additional factor, stromal-derived factor 1 (SDF-1). Author Affiliation: (1) The Center for Transgene Technology and Gene Therapy, Flanders Interuniversity Institute for Biotechnology, University of Leuven, B-3000 Leuven, Belgium

Summary Glucagon, the principal hyperglycemic hormone, is secreted from pancreatic islet α cells as part of the counter-regulatory response to hypoglycemia. Hence, secretory output from α cells is under high demand in conditions of low glucose supply. Many tissues oxidize fat as an alternate energy substrate. Here, we show that glucagon secretion in low glucose conditions is maintained by fatty acid metabolism in both mouse and human islets, and that inhibiting this metabolic pathway profoundly decreases glucagon output by depolarizing α cell membrane potential and decreasing action potential amplitude. We demonstrate, by using experimental and computational approaches, that this is not mediated by the K ATP channel, but instead due to reduced operation of the Na + -K + pump. These data suggest that counter-regulatory secretion of glucagon is driven by fatty acid metabolism, and that the Na + -K + pump is an important ATP-dependent regulator of α cell function. [ABSTRACT FROM AUTHOR]

Summary AXL is activated by its ligand GAS6 and is expressed in triple-negative breast cancer cells. In the current study, we report AXL expression in HER2-positive (HER2 + ) breast cancers where it correlates with poor patient survival. Using murine models of HER2 + breast cancer, Axl, but not its ligand Gas6, was found to be essential for metastasis. We determined that AXL is required for intravasation, extravasation, and growth at the metastatic site. We found that AXL is expressed in HER2 + cancers displaying epithelial-to-mesenchymal transition (EMT) signatures where it contributes to sustain EMT. Interfering with AXL in a patient-derived xenograft (PDX) impaired transforming growth factor β (TGF-β)-induced cell invasion. Last, pharmacological inhibition of AXL specifically decreased the metastatic burden of mice developing HER2 + breast cancer. Our data identify AXL as a potential anti-metastatic co-therapeutic target for the treatment of HER2 + breast cancers. [ABSTRACT FROM AUTHOR]

Summary Hippocampal neurogenesis is important for certain forms of cognition, and failing neurogenesis has been implicated in neuropsychiatric diseases. The neurogenic capacity of hippocampal neural stem/progenitor cells (NSPCs) depends on a balance between quiescent and proliferative states. Here, we show that the rate of fatty acid oxidation (FAO) regulates the activity of NSPCs. Quiescent NSPCs show high levels of carnitine palmitoyltransferase 1a (Cpt1a)-dependent FAO, which is downregulated in proliferating NSPCs. Pharmacological inhibition and conditional deletion of Cpt1a in vitro and in vivo leads to altered NSPC behavior, showing that Cpt1a-dependent FAO is required for stem cell maintenance and proper neurogenesis. Strikingly, manipulation of malonyl-CoA, the metabolite that regulates levels of FAO, is sufficient to induce exit from quiescence and to enhance NSPC proliferation. Thus, the data presented here identify a shift in FAO metabolism that governs NSPC behavior and suggest an instructive role for fatty acid metabolism in regulating NSPC activity. [ABSTRACT FROM AUTHOR]

Summary Peripheral tolerance is crucial for avoiding activation of self-reactive T cells to tissue-restricted antigens . Sterile tissue injury can break peripheral tolerance, but it is unclear how autoreactive T cells get activated in response to self. An example of a sterile injury is myocardial infarction (MI). We hypothesized that tissue necrosis is an activator of dendritic cells (DCs), which control tolerance to self-antigens. DC subsets of a murine healthy heart consisted of IRF8-dependent conventional (c)DC1, IRF4-dependent cDC2, and monocyte-derived DCs. In steady state, cardiac self-antigen α-myosin was presented in the heart-draining mediastinal lymph node (mLN) by cDC1s, driving the proliferation of antigen-specific CD4 + TCR-M T cells and their differentiation into regulatory cells (Tregs). Following MI, all DC subsets infiltrated the heart, whereas only cDCs migrated to the mLN. Here, cDC2s induced TCR-M proliferation and differentiation into interleukin-(IL)-17/interferon-(IFN)γ-producing effector cells. Thus, cardiac-specific autoreactive T cells get activated by mature DCs following myocardial infarction. [ABSTRACT FROM AUTHOR]

Summary Hypoxic tumor-associated macrophages (TAMs) acquire angiogenic and immunosuppressive properties. Yet it remains unknown if metabolic changes influence these functions. Here, we argue that hypoxic TAMs strongly upregulate the expression of REDD1, a negative regulator of mTOR. REDD1-mediated mTOR inhibition hinders glycolysis in TAMs and curtails their excessive angiogenic response, with consequent formation of abnormal blood vessels. Accordingly, REDD1 deficiency in TAMs leads to the formation of smoothly aligned, pericyte-covered, functional vessels, which prevents vessel leakiness, hypoxia, and metastases. Mechanistically, highly glycolytic REDD1-deficient TAMs outcompete endothelial cells for glucose usage that thwarts vascular hyperactivation and promotes the formation of quiescent vascular junctions. Tuning down glycolysis in REDD1 knockout TAMs re-establishes abnormal angiogenesis and metastases. On this basis, we prove that the anti-tumor effect of mTOR inhibitors is partly countered by the deleterious outcome of these drugs on TAMs. Our data provide a functional link between TAM metabolism and tumor angiogenesis. [ABSTRACT FROM AUTHOR]

Summary Neuronal function is highly sensitive to changes in oxygen levels, but how hypoxia affects dendritic spine formation and synaptogenesis is unknown. Here we report that hypoxia, chemical inhibition of the oxygen-sensing prolyl hydroxylase domain proteins (PHDs), and silencing of Phd2 induce immature filopodium-like dendritic protrusions, promote spine regression, reduce synaptic density, and decrease the frequency of spontaneous action potentials independently of HIF signaling. We identified the actin cross-linker filamin A (FLNA) as a target of PHD2 mediating these effects. In normoxia, PHD2 hydroxylates the proline residues P2309 and P2316 in FLNA, leading to von Hippel-Lindau (VHL)-mediated ubiquitination and proteasomal degradation. In hypoxia, PHD2 inactivation rapidly upregulates FLNA protein levels because of blockage of its proteasomal degradation. FLNA upregulation induces more immature spines, whereas Flna silencing rescues the immature spine phenotype induced by PHD2 inhibition. [ABSTRACT FROM AUTHOR]

Summary Cell-based therapy is a promising strategy in regenerative medicine, but the poor survival rate of the implanted cells remains a major challenge and limits clinical translation. We preconditioned periosteal cells to the hypoxic and ischemic environment of the bone defect site by deleting prolyl hydroxylase domain-containing protein 2 (PHD2), resulting in hypoxia-inducible factor 1 alpha (HIF-1α) stabilization. This strategy increased postimplantation cell survival and improved bone regeneration. The enhanced cell viability was angiogenesis independent but relied on combined changes in glutamine and glycogen metabolism. HIF-1α stabilization stimulated glutaminase-mediated glutathione synthesis, maintaining redox homeostasis at baseline and during oxidative or nutrient stress. Simultaneously, HIF-1α signaling increased glycogen storage, preventing an energy deficit during nutrient or oxygen deprivation. Pharmacological inhibition of PHD2 recapitulated the adaptations in glutamine and glycogen metabolism and, consequently, the beneficial effects on cell survival. Thus, targeting cellular metabolism is an appealing strategy for bone regeneration and cell-based therapy in general. [ABSTRACT FROM AUTHOR]

T cells dynamically rewire their metabolism during an immune response. We applied single-cell RNA sequencing to CD8+ T cells activated and differentiated in vitro in physiological medium to resolve these metabolic dynamics. We identify a differential time-dependent reliance of activating T cells on the synthesis versus uptake of various non-essential amino acids, which we corroborate with functional assays. We also identify metabolic genes that potentially dictate the outcome of T cell differentiation, by ranking them based on their expression dynamics. Among them, we find asparagine synthetase (Asns), whose expression peaks for effector T cells and decays toward memory formation. Disrupting these expression dynamics by ASNS overexpression promotes an effector phenotype, enhancing the anti-tumor response of adoptively transferred CD8+ T cells in a mouse melanoma model. We thus provide a resource of dynamic expression changes during CD8+ T cell activation and differentiation, and identify ASNS expression dynamics as a modulator of CD8+ T cell differentiation. [Display omitted] • scRNA-seq defines the metabolic dynamics of activating/differentiating CD8+ T cells • The expression dynamics of ASNS modulate the outcome of CD8+ T cell differentiation • ASNS overexpression enhances CD8+ T cell effector function and anti-tumor responses T cells dynamically rewire their metabolism during an immune response. Fernández-García et al. use single-cell RNA sequencing on CD8+ T cells transitioning in vitro through the immune response cascade to unravel these dynamics and find a crucial role of asparagine synthetase expression in modulating effector T cell differentiation, function, and anti-tumor responses. [ABSTRACT FROM AUTHOR]

Growth factor therapies to induce angiogenesis and thereby enhance the blood perfusion, hold tremendous potential to address the shortcomings of current impaired wound care modalities. Vascular endothelial growth factor stimulates (VEGF) wound healing via multiple mechanisms. Poly(lactic- co -glycolic acid) (PLGA) supplies lactate that accelerates neovascularization and promotes wound healing. Hence, we hypothesized that the administration of VEGF encapsulated in PLGA nanoparticles (PLGA-VEGF NP) would promote fast healing due to the sustained and combined effects of VEGF and lactate. In a splinted mouse full thickness excision model, compared with untreated, VEGF and PLGA NP, PLGA-VEGF NP treated wounds showed significant granulation tissue formation with higher collagen content, re-epithelialization and angiogenesis. The cellular and molecular studies revealed that PLGA-VEGF NP enhanced the proliferation and migration of keratinocytes and upregulated the expression of VEGFR2 at mRNA level. We demonstrated the combined effects of lactate and VEGF for active healing of non-diabetic and diabetic wounds. From the Clinical Editor The study of wound healing has been under a tremendous amount of research over recent years. In diabetic wounds, vasculopathy leading to localized ischemia would often result in delayed 
wound healing. In this article, the authors encapsulated vascular endothelial growth factor stimulates (VEGF) in PLGA nanoparticles and studies the potential pro-healing effects. It was found that the combination of these two components provided synergistic actions for healing. The encouraging results should provide a basis for combination therapy in the future. [ABSTRACT FROM AUTHOR]

Summary Metabolic switches in various immune cell subsets enforce phenotype and function. In the present study, we demonstrate that the active form of vitamin D, 1,25-dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ), induces human monocyte-derived tolerogenic dendritic cells (DC) by metabolic reprogramming. Microarray analysis demonstrated that 1,25(OH) 2 D 3 upregulated several genes directly related to glucose metabolism, tricarboxylic acid cycle (TCA), and oxidative phosphorylation (OXPHOS). Although OXPHOS was promoted by 1,25(OH) 2 D 3 , hypoxia did not change the tolerogenic function of 1,25(OH) 2 D 3 -treated DCs. Instead, glucose availability and glycolysis, controlled by the PI3K/Akt/mTOR pathway, dictate the induction and maintenance of the 1,25(OH) 2 D 3 -conditioned tolerogenic DC phenotype and function. This metabolic reprogramming is unique for 1,25(OH) 2 D 3 , because the tolerogenic DC phenotype induced by other immune modulators did not depend on similar metabolic changes. We put forward that these metabolic insights in tolerogenic DC biology can be used to advance DC-based immunotherapies, influencing DC longevity and their resistance to environmental metabolic stress. [ABSTRACT FROM AUTHOR]

A functional electron transport chain (ETC) is crucial for supporting bioenergetics and biosynthesis. Accordingly, ETC inhibition decreases proliferation in cancer cells but does not seem to impair stem cell proliferation. However, it remains unclear how stem cells metabolically adapt. In this study, we show that pharmacological inhibition of complex III of the ETC in skeletal stem and progenitor cells induces glycolysis side pathways and reroutes the tricarboxylic acid (TCA) cycle to regenerate NAD+ and preserve cell proliferation. These metabolic changes also culminate in increased succinate and 2-hydroxyglutarate levels that inhibit Ten-eleven translocation (TET) DNA demethylase activity, thereby preserving self-renewal and multilineage potential. Mechanistically, mitochondrial malate dehydrogenase and reverse succinate dehydrogenase activity proved to be essential for the metabolic rewiring in response to ETC inhibition. Together, these data show that the metabolic plasticity of skeletal stem and progenitor cells allows them to bypass ETC blockade and preserve their self-renewal. [Display omitted] • Skeletal stem/progenitor cells can proliferate upon electron transport chain blockade • Succinate dehydrogenase is reversed with fumarate functioning as electron acceptor • Pyruvate and aspartate are critical for NAD+ regeneration and proliferation • Metabolic changes prevent DNA demethylation and preserve self-renewal Blocking mitochondrial respiration decreases proliferation in tumor cells but not in stem cells, although mechanistic insight is lacking. Tournaire et al. report that skeletal progenitors bypass this inhibition by reversing succinate dehydrogenase activity and using alternative NAD+ regenerating pathways. This metabolic plasticity maintains proliferation and self-renewal, improving bone regeneration. [ABSTRACT FROM AUTHOR]

Summary: Various tumors metastasize via lymph vessels and lymph nodes to distant organs. Even though tumors are hypoxic, the mechanisms of how hypoxia regulates lymphangiogenesis remain poorly characterized. Here, we show that hypoxia reduced vascular endothelial growth factor C (VEGF-C) transcription and cap-dependent translation via the upregulation of hypophosphorylated 4E-binding protein 1 (4E-BP1). However, initiation of VEGF-C translation was induced by hypoxia through an internal ribosome entry site (IRES)-dependent mechanism. IRES-dependent VEGF-C translation was independent of hypoxia-inducible factor 1α (HIF-1α) signaling. Notably, the VEGF-C IRES activity was higher in metastasizing tumor cells in lymph nodes than in primary tumors, most likely because lymph vessels in these lymph nodes were severely hypoxic. Overall, this transcription-independent but translation-dependent upregulation of VEGF-C in hypoxia stimulates lymphangiogenesis in tumors and lymph nodes and may contribute to lymphatic metastasis. [Copyright &y& Elsevier]

Vascular endothelial (VE) cadherin can influence vascular morphogenesis. Research findings reveal that VE-cadherin plays a vital role in controlling vascular endothelial growth factor-A-mediated endothelial survival through a pathway that involves the cytoplasmic domain of VE-cadherin, beta-catenin, vascular endothelial growth factor receptor-2 and P13-kinase. A relationship was also established which links the inhibition of normal vascular development with the loss or truncation of VE-cadherin.

Endothelial cells (ECs) are quiescent for years but can plastically switch to angiogenesis. Vascular sprouting relies on the coordinated activity of migrating tip cells at the forefront and proliferating stalk cells that elongate the sprout. Past studies have identified genetic signals that control vascular branching. Prominent are VEGF, activating tip cells, and Notch, which stimulates stalk cells. After the branch is formed and perfused, ECs become quiescent phalanx cells. Now, emerging evidence has accumulated indicating that ECs not only adapt their metabolism when switching from quiescence to sprouting but also that metabolism regulates vascular sprouting in parallel to the control by genetic signals. [Copyright &y& Elsevier]

Summary: The delivery of blood-borne molecules conveying metabolic information to neural networks that regulate energy homeostasis is restricted by brain barriers. The fenestrated endothelium of median eminence microvessels and tight junctions between tanycytes together compose one of these. Here, we show that the decrease in blood glucose levels during fasting alters the structural organization of this blood-hypothalamus barrier, resulting in the improved access of metabolic substrates to the arcuate nucleus. These changes are mimicked by 2-deoxyglucose-induced glucoprivation and reversed by raising blood glucose levels after fasting. Furthermore, we show that VEGF-A expression in tanycytes modulates these barrier properties. The neutralization of VEGF signaling blocks fasting-induced barrier remodeling and significantly impairs the physiological response to refeeding. These results implicate glucose in the control of blood-hypothalamus exchanges through a VEGF-dependent mechanism and demonstrate a hitherto unappreciated role for tanycytes and the permeable microvessels associated with them in the adaptive metabolic response to fasting. [ABSTRACT FROM AUTHOR]

Background: Patients with long QT syndrome (LQTS) are at increased risk not only for ventricular arrhythmias but also for atrial pathology including atrial fibrillation (AF). Some patients with “lone” AF carry Na+-channel mutations. Objective: The purpose of this study was to determine the mechanisms underlying atrial pathology in LQTS. Methods: In mice with a heterozygous knock-in long QT syndrome type 3 (LQT3) mutant of the cardiac Na+ channel (ΔKPQ-SCN5A) and wild-type (WT) littermates, atrial size, function, and electrophysiologic parameters were measured in intact Langendorff-perfused hearts, and histologic analysis was performed. Results: Atrial action potential duration, effective refractory period, cycle length, and PQ interval were prolonged in ΔKPQ-SCN5A hearts (all P <.05). Flecainide (1 μM) reversed atrial action potential duration prolongation and induced postrepolarization refractoriness (P <.05). Arrhythmias were infrequent during regular rapid atrial rate in both WT and ΔKPQ-SCN5A but were inducible in 15 (38%) of 40 ΔKPQ-SCN5A and 8 (29%) of 28 WT mice upon extrastimulation. Pacing protocols generating rapid alterations in rate provoked atrial extrasystoles and arrhythmias in 6 (66%) of 9 ΔKPQ-SCN5A but in 0 (0%) of 6 WT mice (P <.05). Atrial diameter was increased by nearly 10% in ΔKPQ-SCN5A mice >5 months old without increase in fibrotic tissue. Conclusion: Murine hearts bearing an LQT3 mutation show abnormalities in atrial electrophysiology and subtle changes in atrial dimension, including an atrial arrhythmogenic phenotype on provocation. These results support clinical data suggesting that LQTS mutations can cause atrial pathology and arrhythmogenesis and indicate that murine sodium channel LQTS models may be useful for exploring underlying mechanisms. [ABSTRACT FROM AUTHOR]

Background & Aims: Hypoxia inducible factor (HIF) prolyl hydroxylase inhibitors are protective in mouse models of inflammatory bowel disease (IBD). Here, we investigated the therapeutic target(s) and mechanism(s) involved. Methods: The effect of genetic deletion of individual HIF-prolyl hydroxylase (PHD) enzymes on the development of dextran sulphate sodium (DSS)–induced colitis was examined in mice. Results: PHD1−/−, but not PHD2+/− or PHD3−/−, mice were less susceptible to the development of colitis than wild-type controls as determined by weight loss, disease activity, colon histology, neutrophil infiltration, and cytokine expression. Reduced susceptibility of PHD1−/− mice to colitis was associated with increased density of colonic epithelial cells relative to wild-type controls, which was because of decreased levels of apoptosis that resulted in enhanced epithelial barrier function. Furthermore, with the use of cultured epithelial cells it was confirmed that hydroxylase inhibition reversed DSS-induced apoptosis and barrier dysfunction. Finally, PHD1 levels were increased with disease severity in intestinal tissue from patients with IBD and in colonic tissues from DSS-treated mice. Conclusions: These results imply a role for PHD1 as a positive regulator of intestinal epithelial cell apoptosis in the inflamed colon. Genetic loss of PHD1 is protective against colitis through decreased epithelial cell apoptosis and consequent enhancement of intestinal epithelial barrier function. Thus, targeted PHD1 inhibition may represent a new therapeutic approach in IBD. [ABSTRACT FROM AUTHOR]

Unraveling the mechanism VEGF-receptors modulating metabolism has therapeutic implications. In this issue, Robciuc et al. (2016) demonstrate that VEGF-B, by displacing VEGF-A from VEGFR1 and activating VEGFR2, increases adipose tissue vascularity, improves insulin sensitivity, diminishes obesity, and alleviates metabolic syndrome. [ABSTRACT FROM AUTHOR]

Aerobic organisms developed mechanisms to protect themselves against a shortage of oxygen (O2). Recent studies reveal that O2 sensors, belonging to the novel class of 2-oxoglutarate dependent iron(ii)-dioxygenases, have more important roles in metabolism than anticipated. Here, we provide a “metabolo-centric” overview of the role of the PHD/FIH members of this family in metabolism, in particular on how they regulate O2 supply and consumption, energy compensation and conservation, O2 conformance and hypoxia tolerance, redox and pH homeostasis, and other vital metabolic processes with implications in health and disease. These insights may offer novel opportunities for the treatment of ischemic diseases. [Copyright &y& Elsevier]

Abstract: VEGF was discovered almost 25 years ago, and its angiogenic activity has been extensively studied ever since. Accumulating evidence indicates, however, that VEGF also has direct effects on neuronal cells. VEGF exerts neuroprotective effects on various cultured neurons of the central nervous system. In vivo, VEGF controls the correct migration of facial branchiomotor neurons in the developing hindbrain and stimulates the proliferation of neural stem cells in enriched environments and after cerebral ischemia. Transgenic mice expressing reduced levels of VEGF develop late-onset motor neuron degeneration, reminiscent of amyotrophic lateral sclerosis (ALS), whereas reduced levels of VEGF have been implicated in a polyglutamine-induced model of motor neuron degeneration. Recent data further reveal that intracerebroventricular delivery of recombinant VEGF protein delays disease onset and prolongs survival of ALS rats, whereas intramuscular administration of a VEGF-expressing lentiviral vector increases the life expectancy of ALS mice by as much as 30%. Deciphering the precise role of VEGF at the neurovascular interface promises to uncover new insights into the development and pathology of the nervous system, helpful to design novel strategies to treat (motor) neurodegenerative disorders. [Copyright &y& Elsevier]

Objectives: The purpose of this study was to determine the clinical and biophysical characteristics of a novel SCN5A mutation.Background: Brugada syndrome and isolated cardiac conduction defect have been linked to SCN5A mutations.Methods: Eleven members of a western European family underwent electrophysiologic investigations and mutation analysis of the SCN5A gene. Wild-type and mutant SCN5A channels were expressed in HEK293 cells, and whole cell currents were studied using patch clamp procedures.Results: A novel mutation, R376H, in the first pore segment of SCN5A variably causes Brugada syndrome and/or conduction disease in a single family. Biophysical analysis demonstrated a significant current reduction for the mutant, a pathophysiologic profile consistent with Brugada syndrome and isolated cardiac conduction defect. Among 11 family members, 9 were carriers of the mutation. The proband's initial presentation was a saddleback Brugada ECG, atrial flutter, and diffuse conduction disturbances. He had no inducible ventricular arrhythmias but experienced sudden cardiac death. His brother was affected by atrial flutter and had a clear conduction disorder, but he did not display baseline or evocable ECG signs of Brugada syndrome. He received an implantable cardioverter-defibrillator that delivered one appropriate shock after 1 year of follow-up. The phenotype in the family members was highly variable and ranged from noninducible and inducible asymptomatic carriers of the mutations to isolated conduction disease and to symptomatic Brugada syndrome.Conclusions: We describe the functional characterization of a novel SCN5A pore mutation, R376H, with variable clinical expression in the same family. Differentiating between electrophysiologic entities (Brugada syndrome-isolated cardiac conduction defect) is more challenging. Recognition of factors modifying the clinical presentation may be important for clinical decision making. [ABSTRACT FROM AUTHOR]

Studies of the last decades have revealed the importance of angiogenesis for normal growth and for the pathogenesis of numerous diseases. Much less studied is lymphangiogenesis, the growth of lymphatic vessels, which drain extravasated fluid, proteins, and cells and transport them back to the venous circulation. Nonetheless, insufficient lymphangiogenesis causes incapacitating lymphedema, while lymphatic growth around tumors may facilitate metastatic spread of malignant cells that ultimately kill the patient. The recent discovery of the key lymphangiogenic factors VEGF-C and VEGF-D and their receptor VEGFR-3 has allowed novel insights into how the lymphatic vessels and blood vessels coordinately grow and affect human disease. In addition, these studies have opened novel diagnostic and therapeutic avenues for the treatment of lymphedema and metastasis. This overview highlights the recent insights and developments in the field of lymphatic vascular research. [Copyright &y& Elsevier]

Vascular endothelial growth factor (VEGF)-mediated angiogenesis is an important part of bone formation. To clarify the role of VEGF isoforms in endochondral bone formation, we examined long bone development in mice expressing exclusively the VEGF120 isoform (VEGF120/120 mice). Neonatal VEGF120/120 long bones showed a completely disturbed vascular pattern, concomitant with a 35% decrease in trabecular bone volume, reduced bone growth and a 34% enlargement of the hypertrophic chondrocyte zone of the growth plate. Surprisingly, embryonic hindlimbs at a stage preceding capillary invasion exhibited a delay in bone collar formation and hypertrophic cartilage calcification. Expression levels of marker genes of osteoblast and hypertrophic chondrocyte differentiation were significantly decreased in VEGF120/120 bones. Furthermore, inhibition of all VEGF isoforms in cultures of embryonic cartilaginous metatarsals, through the administration of a soluble receptor chimeric protein (mFlt-1/Fc), retarded the onset and progression of ossification, suggesting that osteoblast and/or hypertrophic chondrocyte development were impaired. The initial invasion by osteoclasts and endothelial cells into VEGF120/120 bones was retarded, associated with decreased expression of matrix metalloproteinase-9. Our findings indicate that expression of VEGF164 and/or VEGF188 is important for normal endochondral bone development, not only to mediate bone vascularization but also to allow normal differentiation of hypertrophic chondrocytes, osteoblasts, endothelial cells and osteoclasts. [Copyright &y& Elsevier]

Sepsis is a potentially lethal syndrome resulting from a maladaptive response to infection. Upon infection, glucocorticoids are produced as a part of the compensatory response to tolerate sepsis. This tolerance is, however, mitigated in sepsis due to a quickly induced glucocorticoid resistance at the level of the glucocorticoid receptor. Here, we show that defects in the glucocorticoid receptor signaling pathway aggravate sepsis pathophysiology by lowering lactate clearance and sensitizing mice to lactate-induced toxicity. The latter is exerted via an uncontrolled production of vascular endothelial growth factor, resulting in vascular leakage and collapse with severe hypotension, organ damage, and death, all being typical features of a lethal form of sepsis. In conclusion, sepsis leads to glucocorticoid receptor failure and hyperlactatemia, which collectively leads to a lethal vascular collapse. [Display omitted] • GCs are essential to establish disease tolerance to sepsis • Genome-wide GC resistance leads to hypoglycemia and hyperlactatemia in sepsis • Hyperlactatemia in combination with GC resistance causes lethal shock • Inhibition of VEGF signaling prevents lactate-induced lethal shock Vandewalle et al. demonstrate that glucocorticoid resistance in sepsis causes dysfunctional gluconeogenesis, thereby contributing to hyperlactatemia. High lactate levels are not toxic by themselves, but when coupled with glucocorticoid resistance, the combination leads to acute toxicity through elevated vascular endothelial growth factor production, vascular leakage, hypotension, and organ damage. [ABSTRACT FROM AUTHOR]

Obesity is an established risk factor for cancer in many tissues. In the mammalian intestine, a pro-obesity high-fat diet (HFD) promotes regeneration and tumorigenesis by enhancing intestinal stem cell (ISC) numbers, proliferation, and function. Although PPAR (peroxisome proliferator-activated receptor) nuclear receptor activity has been proposed to facilitate these effects, their exact role is unclear. Here we find that, in loss-of-function in vivo models, PPARα and PPARδ contribute to the HFD response in ISCs. Mechanistically, both PPARs do so by robustly inducing a downstream fatty acid oxidation (FAO) metabolic program. Pharmacologic and genetic disruption of CPT1A (the rate-controlling enzyme of mitochondrial FAO) blunts the HFD phenotype in ISCs. Furthermore, inhibition of CPT1A dampens the pro-tumorigenic consequences of a HFD on early tumor incidence and progression. These findings demonstrate that inhibition of a HFD-activated FAO program creates a therapeutic opportunity to counter the effects of a HFD on ISCs and intestinal tumorigenesis. [Display omitted] • HFD augments intestinal stemness through PPARδ and PPARα • A PPAR-FAO program enhances stemness and tumorigenicity in a HFD • Loss or inhibition of Cpt1a-mediated FAO blunts the HFD-enhancing effects in ISCs • Early intestinal tumors arising from HFD ISCs are highly sensitive to FAO inhibition Mana et al. demonstrate that a high-fat diet enhances intestinal stemness and tumorigenicity through a PPAR-FAO program. The PPAR family members δ and α redundantly activate a robust FAO program in stem cells where loss or inhibition of CPT1a (the mitochondrial long-chain FAO rate-controlling step) dampens these HFD effects. [ABSTRACT FROM AUTHOR]

Describes the molecular analysis of vascular development and disorders. Formation of blood vessels during embryogenesis; Role of blood vessels in the pathogenesis of vascular disorders; Involvement of fibroblast growth factor in angioblast differentiation.

Ectopic lipid deposition in muscle and liver is associated with the pathogenesis of type II diabetes. Hagberg et al. (2012) report that targeting the vascular endothelial growth factor (VEGF)-B restores insulin sensitivity and glucose tolerance by inhibiting endothelial-to-tissue lipid transport, opening promising avenues for diabetes therapy. [Copyright &y& Elsevier]

Pancreatic cancer is a rare but fatal form of cancer, the fourth highest in absolute mortality. Known risk factors include obesity, diet, and type 2 diabetes; however, the low incidence rate and interconnection of these factors confound the isolation of individual effects. Here, we use epidemiological analysis of prospective human cohorts and parallel tracking of pancreatic cancer in mice to dissect the effects of obesity, diet, and diabetes on pancreatic cancer. Through longitudinal monitoring and multi-omics analysis in mice, we found distinct effects of protein, sugar, and fat dietary components, with dietary sugars increasing Mad2l1 expression and tumor proliferation. Using epidemiological approaches in humans, we find that dietary sugars give a MAD2L1 genotype-dependent increased susceptibility to pancreatic cancer. The translation of these results to a clinical setting could aid in the identification of the at-risk population for screening and potentially harness dietary modification as a therapeutic measure. • Distinct roles for dietary fat, protein, and sugar on murine pancreatic cancer • Dietary glucose triggers Mad2l1 upregulation and tumor cell proliferation in mice • Gene-diet interaction identifies sugar-MAD2L1 link in human pancreatic cancer • Dietary plant fats were protective in human pancreatic cancer susceptibility Dooley et al. used parallel analysis of a murine pancreatic cancer model and a human prospective cohort to study the interaction of diet and pancreatic cancer. Both systems identify complex effects with different dietary components, converging on a link between dietary sugar and the cell-cycle checkpoint gene MAD2L1. [ABSTRACT FROM AUTHOR]

Leigh syndrome is a devastating mitochondrial disease for which there are no proven therapies. We previously showed that breathing chronic, continuous hypoxia can prevent and even reverse neurological disease in the Ndufs4 knockout (KO) mouse model of complex I (CI) deficiency and Leigh syndrome. Here, we show that genetic activation of the hypoxia-inducible factor transcriptional program via any of four different strategies is insufficient to rescue disease. Rather, we observe an age-dependent decline in whole-body oxygen consumption. These mice exhibit brain tissue hyperoxia, which is normalized by hypoxic breathing. Alternative experimental strategies to reduce oxygen delivery, including breathing carbon monoxide (600 ppm in air) or severe anemia, can reverse neurological disease. Therefore, unused oxygen is the most likely culprit in the pathology of this disease. While pharmacologic activation of the hypoxia response is unlikely to alleviate disease in vivo , interventions that safely normalize brain tissue hyperoxia may hold therapeutic potential. • The Ndufs4 KO mouse model of mitochondrial Leigh syndrome exhibits brain hyperoxia • Genetically activating the hypoxia transcriptional response is not beneficial • CO treatment and anemia reverse disease by decreasing oxygen delivery Leigh syndrome is a severe mitochondrial disorder. Here, Jain et al. show, in a mouse model of the disease, that excess oxygen in the brain is a likely cause of tissue damage and that distinct interventions that reduce oxygen delivery to the brain can prevent and even reverse the neurological disease, likely by normalizing tissue hyperoxia. [ABSTRACT FROM AUTHOR]

Angiogenesis is crucial for the development of the blood vasculature during embryogenesis, but also contributes to cancer and other diseases. While therapeutic targeting of endothelial cells (ECs) through growth factor inhibition is limited by insufficient efficacy and resistance, a new paradigm for modulating angiogenesis by targeting EC metabolism has emerged. Findings from the past decade highlight how ECs adapt their metabolism to proliferate or migrate during vessel sprouting, or to maintain the vascular barrier and protect themselves against oxidative stress in the high-oxygen environment they are exposed to in healthy conditions. We overview key endothelial metabolic pathways underlying the different EC phenotypes, as well as potential opportunities for targeting EC metabolism in therapeutic settings. We postulated in 2009 that the formation of new blood vessels by ECs requires adaptations of EC metabolic pathways, a concept that now has been experimentally validated. ECs exhibit remarkable plasticity both at the phenotypic and metabolic (transcriptome) levels. Preclinical studies have revealed that targeting specific EC metabolic pathways can offer antiangiogenic benefits. The challenge will be to translate these findings to the clinic. [ABSTRACT FROM AUTHOR]

Background & Aims Histamine sensitizes the nociceptor transient reporter potential channel V1 (TRPV1) and has been shown to contribute to visceral hypersensitivity in animals. We investigated the role of TRPV1 in irritable bowel syndrome (IBS) and evaluated if an antagonist of histamine receptor H1 (HRH1) could reduce symptoms of patients in a randomized placebo-controlled trial. Methods By using live calcium imaging, we compared activation of submucosal neurons by the TRPV1 agonist capsaicin in rectal biopsy specimens collected from 9 patients with IBS (ROME 3 criteria) and 15 healthy subjects. The sensitization of TRPV1 by histamine, its metabolite imidazole acetaldehyde, and supernatants from biopsy specimens was assessed by calcium imaging of mouse dorsal root ganglion neurons. We then performed a double-blind trial of patients with IBS (mean age, 31 y; range, 18–65 y; 34 female). After a 2-week run-in period, subjects were assigned randomly to groups given either the HRH1 antagonist ebastine (20 mg/day; n = 28) or placebo (n = 27) for 12 weeks. Rectal biopsy specimens were collected, barostat studies were performed, and symptoms were assessed (using the validated gastrointestinal symptom rating scale) before and after the 12-week period. Patients were followed up for an additional 2 weeks. Abdominal pain, symptom relief, and health-related quality of life were assessed on a weekly basis. The primary end point of the study was the effect of ebastine on the symptom score evoked by rectal distension. Results TRPV1 responses of submucosal neurons from patients with IBS were potentiated compared with those of healthy volunteers. Moreover, TRPV1 responses of submucosal neurons from healthy volunteers could be potentiated by their pre-incubation with histamine; this effect was blocked by the HRH1 antagonist pyrilamine. Supernatants from rectal biopsy specimens from patients with IBS, but not from the healthy volunteers, sensitized TRPV1 in mouse nociceptive dorsal root ganglion neurons via HRH1; this effect could be reproduced by histamine and imidazole acetaldehyde. Compared with subjects given placebo, those given ebastine had reduced visceral hypersensitivity, increased symptom relief (ebastine 46% vs placebo 13%; P = .024), and reduced abdominal pain scores (ebastine 39 ± 23 vs placebo 62 ± 22; P = .0004). Conclusions In studies of rectal biopsy specimens from patients, we found that HRH1-mediated sensitization of TRPV1 is involved in IBS. Ebastine, an antagonist of HRH1, reduced visceral hypersensitivity, symptoms, and abdominal pain in patients with IBS. Inhibitors of this pathway might be developed as a new treatment approach for IBS. ClinicalTrials.gov no: NCT01144832 . [ABSTRACT FROM AUTHOR]

Background & Aims: Portal hypertension is responsible for the major complications associated with cirrhosis. Angiogenesis has been associated with the pathophysiology of portal hypertension. We investigated the role of placental growth factor (PlGF) and tested the effects of monoclonal antibodies against PlGF (αPlGF) in a mouse model of portal hypertension. Methods: Using a mouse model of prehepatic portal hypertension, we measured PlGF levels in the mesenteric tissue at different time points. We used knockout mice and αPlGF to determine the role of PlGF in the splanchnic hyperdynamic system and portosystemic collateral formation, examining its effects before and after portal hypertension was induced. Results: PlGF was significantly up-regulated in the mesenteric tissue of mice with portal hypertension. Compared with wild-type animals, the vascular density in the mesentery was reduced in PlGF knockout hypertensive mice, preventing collateral formation and attenuation of mesenteric artery flow without affecting portal pressure. In the prevention study, αPlGF showed similar findings as in the knockout study. In mice with portal hypertension, administration of αPlGF resulted in a 32% decrease in portal pressure, compared with mice given immunoglobulin G1 (control). Conclusions: Pathologic angiogenesis in the mesenteric tissues of mice with portal hypertension is mediated by PlGF. Blocking PlGF could be an effective strategy for reducing collateral formation and lowering portal pressure; further research into the effects in cirrhosis is warranted. [Copyright &y& Elsevier]