High Metabolic Demand Research Articles

Cellular metabolic adaptations in rheumatoid arthritis and their therapeutic implications.

Activation of endothelium and immune cells is fundamental to the initiation of autoimmune diseases such as rheumatoid arthritis (RA), and it results in trans-endothelial cell migration and synovial fibroblast proliferation, leading to joint destruction. In RA, the synovial microvasculature is highly dysregulated, resulting in inefficient oxygen perfusion to the synovium, which, along with the high metabolic demands of activated immune and stromal cells, leads to a profoundly hypoxic microenvironment. In inflamed joints, infiltrating immune cells and synovial resident cells have great requirements for energy and nutrients, and they adapt their metabolic profiles to generate sufficient energy to support their highly activated inflammatory states. This shift in metabolic capacity of synovial cells enables them to produce the essential building blocks to support their proliferation, activation and invasiveness. Furthermore, it results in the accumulation of metabolic intermediates and alteration of redox-sensitive pathways, affecting signalling pathways that further potentiate the inflammatory response. Importantly, the inflamed synovium is a multicellular tissue, with cells differing in their metabolic requirements depending on complex cell-cell interactions, nutrient supply, metabolic intermediates and transcriptional regulation. Therefore, understanding the complex interplay between metabolic and inflammatory pathways in synovial cells in RA will provide insight into the underlying mechanisms of disease pathogenesis.

Anatomy of the heart of the leatherback turtle.

Non‐crocodylian reptiles have hearts with a single ventricle, which is partially separated by a muscular ridge that provides some separation of blood flows. An exceptional situation exists in monitor lizards and pythons, where the ventricular left side generates a much higher systolic blood pressure than the right side, thus resembling mammals and birds. This functional division of the ventricle depends on a large muscular ridge and may relate to high metabolic demand. The large leatherback turtle (<1000 kg), with its extensive migrations and elevated body temperatures, may have similar adaptations. We report on the anatomy of the hearts of two leatherback turtles. One stranded in Ballum, Denmark in 2020, and was examined in detail, supplemented by observations and photos of an additional stranding specimen from Canada. The external morphology of the leatherback heart resembles that of other turtles, but it is large. We made morphometric measurements of the Ballum heart and created an interactive 3D model using high‐resolution MRI. The volume of the ventricle was 950 ml, from a turtle of 300 kg, which is proportionally almost twice as large as in other reptiles. The Ballum heart was compared to MRI scans of the hearts of a tortoise, a python, and a monitor lizard. Internally, the leatherback heart is typical of non‐crocodylian reptiles and did not contain the well‐developed septation found in pythons and monitor lizards. We conclude that if leatherback turtles have exceptional circulation needs, they are sustained with a relatively large but otherwise typical non‐crocodylian reptile heart.

Chinese natural compound decreases pacemaking of rabbit cardiac sinoatrial cells by targeting second messenger regulation of f-channels.

Tongmai Yangxin (TMYX) is a complex compound of the Traditional Chinese Medicine (TCM) used to treat several cardiac rhythm disorders; however, no information regarding its mechanism of action is available. In this study we provide a detailed characterization of the effects of TMYX on the electrical activity of pacemaker cells and unravel its mechanism of action. Single-cell electrophysiology revealed that TMYX elicits a reversible and dose-dependent (2/6 mg/ml) slowing of spontaneous action potentials rate (-20.8/-50.2%) by a selective reduction of the diastolic phase (-50.1/-76.0%). This action is mediated by a negative shift of the If activation curve (-6.7/-11.9 mV) and is caused by a reduction of the cyclic adenosine monophosphate (cAMP)-induced stimulation of pacemaker channels. We provide evidence that TMYX acts by directly antagonizing the cAMP-induced allosteric modulation of the pacemaker channels. Noticeably, this mechanism functionally resembles the pharmacological actions of muscarinic stimulation or β-blockers, but it does not require generalized changes in cytoplasmic cAMP levels thus ensuring a selective action on rate. In agreement with a competitive inhibition mechanism, TMYX exerts its maximal antagonistic action at submaximal cAMP concentrations and then progressively becomes less effective thus ensuring a full contribution of If to pacemaker rate during high metabolic demand and sympathetic stimulation.

Modular lung ventilation in Boa constrictor.

The evolution of constriction and of large prey ingestion within snakes are key innovations that may explain the remarkable diversity, distribution and ecological scope of this clade, relative to other elongate vertebrates. However, these behaviors may have simultaneously hindered lung ventilation such that early snakes may have had to circumvent these mechanical constraints before those behaviors could evolve. Here, we demonstrate that Boa constrictor can modulate which specific segments of ribs are used to ventilate the lung in response to physically hindered body wall motions. We show that the modular actuation of specific segments of ribs likely results from active recruitment or quiescence of derived accessory musculature. We hypothesize that constriction and large prey ingestion were unlikely to have evolved without modular lung ventilation because of their interference with lung ventilation, high metabolic demands and reliance on sustained lung convection. This study provides a new perspective on snake evolution and suggests that modular lung ventilation evolved during or prior to constriction and large prey ingestion, facilitating snakes' remarkable radiation relative to other elongate vertebrates.

Mitochondria in cone photoreceptors act as microlenses to enhance photon delivery and confer directional sensitivity to light.

Mammalian photoreceptors aggregate numerous mitochondria, organelles chiefly for energy production, in the ellipsoid region immediately adjacent to the light-sensitive outer segment to support the high metabolic demands of phototransduction. However, these complex, lipid-rich organelles are also poised to affect light passage into the outer segment. Here, we show, via live imaging and simulations, that despite this risk of light scattering or absorption, these tightly packed mitochondria “focus” light for entry into the outer segment and that mitochondrial remodeling affects such light concentration. This “microlens”-like feature of cone mitochondria delivers light with an angular dependence akin to the Stiles-Crawford effect (SCE), providing a simple explanation for this essential visual phenomenon that improves resolution. This new insight into the optical role of mitochondria is relevant for the interpretation of clinical ophthalmological imaging, lending support for the use of SCE as an early diagnostic tool in retinal disease.

Effects of physical therapy with neuromuscular electrical stimulation in acute and late septic shock patients: A randomised crossover clinical trial.

BackgroundPatients with sepsis and immobility in the intensive care unit are associated with muscle weakness, and early mobilisation can counteract it. However, during septic shock, mobilisation is often delayed due to the severity of the illness. Neuromuscular electrical stimulation (NMES) may be an alternative to mobilise these patients early. This study aims to identify whether NMES performed within the first 72 hours of septic shock diagnosis or later is safe from a metabolic perspective.MethodsThis is the analysis of two randomised controlled crossover studies. Patients with acute septic shock (within the first 72 hours of diagnosis) and sepsis and septic shock in the late phase (after 72 hours of diagnosis) were eligible. Patients were submitted in a random order to the intervention protocol (dorsal decubitus position with the lower limbs raised and NMES) and control (dorsal decubitus position with the lower limbs raised without NMES). The patients were allocated in group 1 (intervention and control) or group 2 (control and intervention) with a wash-out period of 4 to 6 hours. Metabolic variables were evaluated by indirect calorimetry.ResultsSixteen patients were analysed in the acute septic shock study and 21 in the late sepsis/septic shock study. There were no significant differences between Oxygen Consumption (VO2) values in the acute phase of septic shock when the baseline period, intervention, and control protocols were compared (186.59 ± 46.10; 183.64 ± 41.39; 188.97 ± 44.88, p>0.05- expressed in mL/Kg/min). The same was observed when the VO2 values in the late phase were compared (224.22 ± 53.09; 226.20 ± 49.64; 226.79 ± 58.25, p>0.05). The other metabolic variables followed the same pattern, with no significant differences between the protocols. When metabolic variables were compared between acute to late phase, significant differences were observed (p<0.05).ConclusionsAs metabolic rates in septic shock patients had no increase during NMES, either in the first 72 hours of diagnosis or later, NMES can be considered safe from a metabolic viewpoint, even despite the higher metabolic demand in the acute phase of shock.Trial registrationNCT03193164; NCT03815994. Registered on June 5, 2017; November 13, 2018 (clinicaltrials.gov/).

Invited Session II: Retinal mechanisms mediating vision: Mitochondria in cone photo-receptors act as microlenses to enhance photon delivery and confer directional sensitivity to light

Mitochondria are cellular organelles chiefly intended for energy production. Mammalian photoceptors aggregate numerous mitochondria in the ellipsoid region immediately adjacent to their light-sensitive outer segments to support the high metabolic demands of phototransduction. However, these complex, lipid-rich organelles are also poised to affect the passage of light into the outer segment, an essential step in the transduction of physical energy into cellular signals. Here we show, via live-imaging and computational modeling, that despite this risk of light scattering or absorption, such tightly packed mitochondria concentrate light for entry into the outer segment. Intriguingly, this "microlens"-like feature of cone mitochondria delivers light with an angular dependence akin to the Stiles-Crawford effect (SCE), providing a simple explanation for this essential visual phenomenon that improves resolution. Given the pivotal role that photoreceptor mitochondria play in multiple retinal degenerative diseases, this new insight into their optical properties provides critical information for the accurate interpretation of non-invasive ophthalmic imaging results and lends support for using SCE as an early diagnostic tool.

High Iron and Iron Household Protein Contents in Perineuronal Net-Ensheathed Neurons Ensure Energy Metabolism with Safe Iron Handling.

A subpopulation of neurons is less vulnerable against iron-induced oxidative stress and neurodegeneration. A key feature of these neurons is a special extracellular matrix composition that forms a perineuronal net (PN). The PN has a high affinity to iron, which suggests an adapted iron sequestration and metabolism of the ensheathed neurons. Highly active, fast-firing neurons—which are often ensheathed by a PN—have a particular high metabolic demand, and therefore may have a higher need in iron. We hypothesize that PN-ensheathed neurons have a higher intracellular iron concentration and increased levels of iron proteins. Thus, analyses of cellular and regional iron and the iron proteins transferrin (Tf), Tf receptor 1 (TfR), ferritin H/L (FtH/FtL), metal transport protein 1 (MTP1 aka ferroportin), and divalent metal transporter 1 (DMT1) were performed on Wistar rats in the parietal cortex (PC), subiculum (SUB), red nucleus (RN), and substantia nigra (SNpr/SNpc). Neurons with a PN (PN+) have higher iron concentrations than neurons without a PN: PC 0.69 mM vs. 0.51 mM, SUB 0.84 mM vs. 0.69 mM, SN 0.71 mM vs. 0.63 mM (SNpr)/0.45 mM (SNpc). Intracellular Tf, TfR and MTP1 contents of PN+ neurons were consistently increased. The iron concentration of the PN itself is not increased. We also determined the percentage of PN+ neurons: PC 4%, SUB 5%, SNpr 45%, RN 86%. We conclude that PN+ neurons constitute a subpopulation of resilient pacemaker neurons characterized by a bustling iron metabolism and outstanding iron handling capabilities. These properties could contribute to the low vulnerability of PN+ neurons against iron-induced oxidative stress and degeneration.

Interplay between mitochondrial reactive oxygen species, oxidative stress and hypoxic adaptation in facioscapulohumeral muscular dystrophy: Metabolic stress as potential therapeutic target

Facioscapulohumeral muscular dystrophy (FSHD) is characterised by descending skeletal muscle weakness and wasting. FSHD is caused by mis-expression of the transcription factor DUX4, which is linked to oxidative stress, a condition especially detrimental to skeletal muscle with its high metabolic activity and energy demands. Oxidative damage characterises FSHD and recent work suggests metabolic dysfunction and perturbed hypoxia signalling as novel pathomechanisms. However, redox biology of FSHD remains poorly understood, and integrating the complex dynamics of DUX4-induced metabolic changes is lacking.Here we pinpoint the kinetic involvement of altered mitochondrial ROS metabolism and impaired mitochondrial function in aetiology of oxidative stress in FSHD. Transcriptomic analysis in FSHD muscle biopsies reveals strong enrichment for pathways involved in mitochondrial complex I assembly, nitrogen metabolism, oxidative stress response and hypoxia signalling. We found elevated mitochondrial ROS (mitoROS) levels correlate with increases in steady-state mitochondrial membrane potential in FSHD myogenic cells. DUX4 triggers mitochondrial membrane polarisation prior to oxidative stress generation and apoptosis through mitoROS, and affects mitochondrial health through lipid peroxidation. We identify complex I as the primary target for DUX4-induced mitochondrial dysfunction, with strong correlation between complex I-linked respiration and cellular oxygenation/hypoxia signalling activity in environmental hypoxia. Thus, FSHD myogenesis is uniquely susceptible to hypoxia-induced oxidative stress as a consequence of metabolic mis-adaptation. Importantly, mitochondria-targeted antioxidants rescue FSHD pathology more effectively than conventional antioxidants, highlighting the central involvement of disturbed mitochondrial ROS metabolism. This work provides a pathomechanistic model by which DUX4-induced changes in oxidative metabolism impair muscle function in FSHD, amplified when metabolic adaptation to varying O2 tension is required.

Disrupting N-glycan expression on tumor cells boosts chimeric antigen receptor T cell efficacy against solid malignancies.

Immunotherapy with chimeric antigen receptor (CAR)–engineered T cells showed exceptional successes in patients with refractory B cell malignancies. However, first-in-human studies in solid tumors revealed unique hurdles contributing to poor demonstration of efficacy. Understanding the determinants of tumor recognition by CAR T cells should translate into the design of strategies that can overcome resistance. Here, we show that multiple carcinomas express extracellular N-glycans, whose abundance negatively correlates with CAR T cell killing. By knocking out mannoside acetyl-glucosaminyltransferase 5 (MGAT5) in pancreatic adenocarcinoma (PAC), we showed that N-glycans protect tumors from CAR T cell killing by interfering with proper immunological synapse formation and reducing transcriptional activation, cytokine production, and cytotoxicity. To overcome this barrier, we exploited the high metabolic demand of tumors to safely inhibit N-glycans synthesis with the glucose/mannose analog 2-deoxy-d-glucose (2DG). Treatment with 2DG disrupts the N-glycan cover on tumor cells and results in enhanced CAR T cell activity in different xenograft mouse models of PAC. Moreover, 2DG treatment interferes with the PD-1–PD-L1 axis and results in a reduced exhaustion profile of tumor-infiltrating CAR T cells in vivo. The combined 2DG and CAR T cell therapy was successful against multiple carcinomas besides PAC, including those arising from the lung, ovary, and bladder, and with different clinically relevant CAR specificities, such as CD44v6 and CEA. Overall, our results indicate that tumor N-glycosylation regulates the quality and magnitude of CAR T cell responses, paving the way for the rational design of improved therapies against solid malignancies.

Heat Shock Protein 90 as Therapeutic Target for CVDs and Heart Ageing.

Cardiovascular diseases (CVDs) are the leading cause of death globally, representing approximately 32% of all deaths worldwide. Molecular chaperones are involved in heart protection against stresses and age-mediated accumulation of toxic misfolded proteins by regulation of the protein synthesis/degradation balance and refolding of misfolded proteins, thus supporting the high metabolic demand of the heart cells. Heat shock protein 90 (HSP90) is one of the main cardioprotective chaperones, represented by cytosolic HSP90a and HSP90b, mitochondrial TRAP1 and ER-localised Grp94 isoforms. Currently, the main way to study the functional role of HSPs is the application of HSP inhibitors, which could have a different way of action. In this review, we discussed the recently investigated role of HSP90 proteins in cardioprotection, atherosclerosis, CVDs development and the involvements of HSP90 clients in the activation of different molecular pathways and signalling mechanisms, related to heart ageing.

The Role of Branched Chain Amino Acids for Heart Failure in Children

Heart failure is an abnormality of the heart’s structure or function, causing impairment in oxygen delivery to peripheral tissue. The most common causes of heart failure in children are congenital heart disease and cardiomyopathies. Impairment in cardiac function will affect nutritional status such as higher metabolic demands, lower intake, nutrients malabsorption, and failure to thrive. About 86% children with chronic heart failure had malnutrition. Branched chain amino acids (BCAAs) are essential amino acids that involved in protein synthesis, muscle atrophy prevention, and regulating biogenesis of mitochondrial for cardiac energy formation. This review elucidates current findings on BCAAs supplementation for children with heart failure.

Chapter 16 - Neurological effects of respiratory dysfunction

The respiratory and the nervous systems are closely interconnected and are maintained in a fine balance. Central mechanisms maintain strict control of ventilation due to the high metabolic demands of brain which depends on a continuous supply of oxygenated blood along with glucose. Moreover, brain perfusion is highly sensitive to changes in the partial pressures of carbon dioxide and oxygen in blood, which in turn depend on respiratory function. Ventilatory control is strictly monitored and regulated by the central nervous system through central and peripheral chemoreceptors, baroreceptors, the cardiovascular system, and the autonomic nervous system. Disruption in this delicate control of respiratory function can have subtle to devastating neurological effects as a result of ensuing hypoxia or hypercapnia. In addition, pulmonary circulation receives entire cardiac output and this may act as a conduit to transmit infections and also for metastasis of malignancies to brain resulting in neurological dysfunction. Furthermore, many neurological paraneoplastic syndromes can have underlying lung malignancies resulting in respiratory dysfunction. It is essential to understand the underlying mechanisms and the resulting manifestations in order to prevent and effectively manage the many neurological effects of respiratory dysfunction. This chapter explores the various neurological effects of respiratory dysfunction with focus on their pathophysiology, etiologies, clinical features and long-term neurological sequelae.

Evolution of the N-Terminal Regulation of Cardiac Troponin I for Heart Function of Tetrapods: Lungfish Presents an Example of the Emergence of Novel Submolecular Structure to Lead the Capacity of Adaptation.

Troponin-based Ca2+ regulation of striated muscle contraction emerged approximately 700 million years ago with largely conserved functions during evolution. Troponin I (TnI) is the inhibitory subunit of troponin and has evolved into three muscle type-specific isoforms in vertebrates. Cardiac TnI is specifically expressed in the adult heart and has a unique N-terminal extension implicating a specific value during natural selection. The N-terminal extension of cardiac TnI in higher vertebrates contains β-adrenergic-regulated protein kinase A (PKA) phosphorylation sites as a mechanism to enhance cardiac muscle relaxation and facilitate ventricular filling. Phylogenic studies showed that the N-terminal extension of cardiac TnI first emerged in the genomes of early tetrapods as well as primordial lobe-finned fishes such as the coelacanth whereas it is absent in ray-finned fish. This apparently rapid evolution of β-adrenergic regulation of cardiac function suggests a high selection value for the heart of vertebrate animals on land to work under higher metabolic demands. Sequencing and PKA phosphorylation data showed that lungfish cardiac TnI has evolved with an amphibian-like N-terminal extension with prototype PKA phosphorylation sites while its overall structure remained fish like. The data demonstrate that the submolecular structure of TnI may evolve ahead of the whole protein for cardiac muscle contractility to adapt to new environmental conditions. Understanding the evolution of the β-adrenergic regulation of TnI and cardiac adaptation to the increased energetic demands of life on land adds knowledge for the treatment of human heart diseases and failure.

Improved Vascularization and Survival of White Compared to Brown Adipose Tissue Grafts in the Dorsal Skinfold Chamber.

Fat grafting is a frequently applied procedure in plastic surgery for volume reconstruction. Moreover, the transplantation of white adipose tissue (WAT) and brown adipose tissue (BAT) increasingly gains interest in preclinical research for the treatment of obesity-related metabolic defects. Therefore, we herein directly compared the vascularization capacity and survival of WAT and BAT grafts. For this purpose, size-matched grafts isolated from the inguinal WAT pad and the interscapular BAT depot of C57BL/6N donor mice were syngeneically transplanted into the dorsal skinfold chamber of recipient animals. The vascularization and survival of the grafts were analyzed by means of intravital fluorescence microscopy, histology, and immunohistochemistry over an observation period of 14 days. WAT grafts showed an identical microvascular architecture and functional microvessel density as native WAT. In contrast, BAT grafts developed an erratic microvasculature with a significantly lower functional microvessel density when compared to native BAT. Accordingly, they also contained a markedly lower number of CD31-positive microvessels, which was associated with a massive loss of perilipin-positive adipocytes. These findings indicate that in contrast to WAT grafts, BAT grafts exhibit an impaired vascularization capacity and survival, which may be due to their higher metabolic demand. Hence, future studies should focus on the establishment of strategies to improve the engraftment of transplanted BAT.

Prevalence of obstetric complications in multiple pregnancies treated at Hospital José Carrasco Arteaga - IESS, Cuenca-Ecuador from JUne 2014 to June 2019

BACKGROUND: Multiple pregnancy is the development of two or more fetuses simultaneously; but being the human species uniparous par excellence, MP is sensitive to the appearance of complications that affect both the mother and the fetuses, due to the high metabolic demand, hyperplacentation, and uterine distention. Among the most common obstetric and metabolic complications in women with MP are: premature delivery, hypertensive disorders of pregnancy, intrauterine growth restriction, premature rupture of membranes, gestational diabetes, anemia, urinary tract infection, hypothyroidism, and postpartum hemorrhage. The aim of this study is to identify the prevalence and risk factors related to obstetric and metabolic complications in multiple pregnancies. METHODS: An observational, descriptive and correlational cross-sectional study was carried out in the city of Cuenca, at Hospital José Carrasco Arteaga –IESS, during the period of June 2014 to June 201, in the department of obstetrics and gynecology (OBGYN), with a sample of 64 patients with multiple pregnancies. RESULTS: The results showed that 71.42% of the patients presented some of the studied complications. Preterm delivery was the most common obstetric complication, occurring in 79.7% of the patients, followed by preeclampsia, which occurred in 23.5%; while the most frequent metabolic complication was urinary tract infection ( in 37.5% of the patients), followed by anemia, which occurred in 25% of the patients. A statistically significant association (p&lt;0.05) was found between the patient`s age and the presence of premature rupture of membranes. CONCLUSION: 71.42% of women with multiple pregnancy had obstetric or other type of complications. Preterm delivery was the most frequent complication, followed by urinary tract infections, anemia, and preeclampsia. A significant association was found between the age of the mother and the occurrence of premature rupture of membranes.

CSIG-23. ELONGATION CONTROL OF mRNA TRANSLATION DRIVES GROUP 3 MEDULLOBLASTOMA ADAPTATION TO NUTRIENT DEPRIVATION

Abstract Group 3 affiliation and MYC genetic amplification are associated with poor life expectancy and substantial morbidity in children suffering from medulloblastoma (MB). However, the high metabolic demand induced by MYC-driven transformation sensitizes MYC-overexpressing MB to cell death under conditions of nutrient deprivation (ND). Additionally, MYC-driven transformation is known to promote mitochondrial oxidative phosphorylation (OXPHOS). We previously reported that eukaryotic Elongation Factor Kinase 2 (eEF2K), the master regulator of mRNA translation elongation, promotes survival of MYC-overexpressing tumors under ND. Interestingly, eEF2K is overexpressed in MYC-driven MB and our preliminary proteomics data highlight large-scale alterations in OXPHOS components affecting eEF2K deficient MB cells. We therefore hypothesized that eEF2K activity is required for the selective translation of mRNAs needed for efficient OXPHOS, and for the progression of MYC-driven MB. We pefrormed Multiplexed enhanced Protein Dynamic Mass Spectrometry in eEF2K knockdown MYC-overexpressing D425 MB cells to identify mRNAs selectively translated upon eEF2K activation. Messenger RNAs encoding multiple (9 out of 10 detected) components of the mitochondrial OXPHOS pathway are selectively translated upon eEF2K activation. Inactivation of eEF2K by genetic KO leads to the disassembly of electron transport chain (ETC) complexes I-IV without affecting mRNA levels of their respective components. Consistently, eEF2K KO MB cells display decreased mitochondrial membrane potential and 20% increased proton leak thorough the mitochondrial membrane. In addition, eEF2K inactivation results in increased Group 3 MB cell death under ND and doubles survival of MB bearing mice fed with calorie restricted diets (p&amp;lt; 0.05). Control of mRNA translation elongation by eEF2K is critical for mitochondrial ETC complex assembly and efficient OXPHOS in MYC-overexpressing MB, likely representing an adaptive response by which MYC-driven MB cells cope with acute metabolic stress. Future therapeutic studies will aim to combine eEF2K inhibition with caloric restriction mimetic drugs as eEF2K activity appears critical under metabolic stress conditions.

Phosphatases of regenerating liver are key regulators of metabolism in cancer cells - role of Serine/Glycine metabolism.

Purpose of reviewPhosphatases of regenerating liver (PRL) are dual-specificity phosphatases and comprise three members, PRL-1, -2 and -3. Despite the importance of PRLs as oncoproteins, there is no consensus function for this family of phosphatases. In the current review paper, we summarize recent findings on the role of PRLs in metabolic regulation.Recent findingsReprogramming of cellular metabolism is a cancer hallmark. Glucose is the major source of energy in cells. Glucose metabolism occurs through the glycolysis and can continue through the pathways such as serine synthesis pathway or the tricarboxylic acid cycle (TCA). Magnesium (Mg2+), the second most abundant cation in cells, plays an essential role in energy production by acting as a cofactor for most enzymes involved in glycolysis and in TCA. Recent findings have shown that the PRL family has a role in metabolic reprogramming mediated by (1) Mg2+ homeostasis, (2) shifting the energy source preference to glucose consumption and fueling serine/glycine pathway and (3) regulating PI3 kinase/Mammalian target of rapamycin complex. Both the phosphatase and nonphosphatase activity of PRLs appear to be important for its oncogenic role.SummaryThe PRL family contributes to the metabolic plasticity of cancer cells and, thereby, allows cancer cells to meet the high metabolic demands required for cell proliferation.

Reduced Intensity Hematopoietic Cell Transplantation Improves Cerebral Hemodynamics in Children with Sickle Cell Disease

IntroductionAllogeneic hematopoietic cell transplantation (HCT) is increasingly being utilized in patients with sickle cell disease (SCD) to prevent progressive organ dysfunction, including for primary or secondary stroke prevention. However, outcomes after HCT have mostly been evaluated using broad measures such as overall survival and event free survival with limited direct physiologic evidence of improved cerebral hemodynamics. Cerebral blood flow (CBF; mL blood/100 g tissue/min) is increased in SCD to compensate for chronic anemia, reduced oxygen carrying capacity and to maintain adequate oxygen delivery to the brain tissue. In SCD patients, CBF is inversely associated with intelligence quotient (Strouse JJ, et al. Blood. 2006;108(1):379-381.) and working memory (Prussien KV, et al. Stroke. 2021;52(5):1830-1834.) and has been shown to improve with blood transfusions (Guilliams KP, et al. Blood. 2018;131(9):1012-1021.). Assessment of CBF may help predict long-term neurocognitive outcomes in patients with SCD and assess therapeutic responses to therapies. Additionally, the high metabolic demand of the brain potentially makes assessment of CBF a sensitive predictor of future multiorgan damage in patients with SCD and hence may be useful to help determine eligibility of patients for curative therapies.MethodsWe performed anatomical and hemodynamic magnetic resonance imaging (MRI) of the brain prior to, and at 6 months after HCT in children with SCD undergoing a reduced intensity conditioning based HCT on a clinical study (NCT04362293). All patients received pretransplant conditioning with hydroxyurea, azathioprine, alemtuzumab, thiotepa and low dose total body irradiation (200-400 cGy). All patients received an unmanipulated mobilized peripheral blood derived hematopoietic stem and progenitor cell graft. One patient who received the graft from a haploidentical (HAPLO) donor also received post-transplant cyclophosphamide. Graft versus host disease prophylaxis comprised of sirolimus. A 3-dimensional (3D) T1 sequence was used for gray/white matter segmentation. 3D-pulsed arterial spin labeling (ASL) perfusion imaging (3 mm isotropic) was acquired to measure resting CBF. Mean CBF values were calculated from gray matter. Mean ± standard deviation and median values for various variables are presented.ResultsFour consecutive patients had 2 serial MRIs performed (one before HCT and another 6 months after HCT). Median age at HCT was 14.5 years. Indications for HCT, donor type and whether patients were receiving chronic transfusion therapy (CTT) prior to HCT are indicated in the Table. No patient had prior evidence of overt stroke. All patients engrafted and had >99% donor myeloid chimerism at the time of the post-HCT imaging. Mean pre-HCT hemoglobin was 8.7 ± 0.8 g/dL (median 8.6 g/dL) and it increased to 12.5 ± 2.1 g/dL (median 12.4 g/dL) at 6 months after HCT. All patients exhibited elevated resting CBF values prior to HCT (123.8 ± 32.2 mL blood/100 g tissue/min, median 112.8 mL blood/100 g tissue/min), that decreased following HCT (71.1 ± 32.1 mL blood/100 g tissue/min, median 72.8 mL blood/100 g tissue/min) (Table and Figure). None of the patients had any clinical neurological complications or imaging evidence of new infarcts or anatomical abnormalities in the follow up period.ConclusionOur preliminary results indicate that it is feasible to quantify CBF in patients with SCD before and after HCT using MRI. We demonstrate that cerebral hemodynamics improve after HCT in children with SCD, indicated by a decrease in CBF to near normal values (normal CBF ~80 mL blood/100 g tissue/min). The more substantial changes (-50% and -78%) are seen in children who were not receiving CTT, suggesting that CTT might partially mitigate CBF elevation prior to HCT. Nevertheless, 2 patients receiving CTT prior to HCT also had a further modest decrease in CBF after HCT (-5% and -18%). We plan to follow these changes at serial time points annually after HCT and correlate them with changes in neurocognitive functioning and other functional MRI measures. Improved CBF is expected to reduce stroke risk and may also preserve or improve neurocognitive functioning, and prospective monitoring of these outcomes are underway.Data on all the study participants who have undergone an HCT and had 2 serial MRIs performed by the ASH annual meeting will be presented. [Display omitted] DisclosuresSharma: Vertex Pharmaceuticals/CRISPR Therapeutics: Other: Salary support paid to institution; Medexus Inc: Consultancy; CRISPR Therapeutics: Other, Research Funding; Novartis: Other: Salary support paid to institution; Spotlight Therapeutics: Consultancy; Vindico Medical Education: Honoraria. Triplett: Miltenyi: Other: Travel, meeting registration. Hankins: Vindico Medical Education: Consultancy; UpToDate: Consultancy; Global Blood Therapeutics: Consultancy; Bluebird Bio: Consultancy.

Targetable Pathways for Alleviating Mitochondrial Dysfunction in Neurodegeneration of Metabolic and Non-Metabolic Diseases.

Many neurodegenerative and inherited metabolic diseases frequently compromise nervous system function, and mitochondrial dysfunction and oxidative stress have been implicated as key events leading to neurodegeneration. Mitochondria are essential for neuronal function; however, these organelles are major sources of endogenous reactive oxygen species and are vulnerable targets for oxidative stress-induced damage. The brain is very susceptible to oxidative damage due to its high metabolic demand and low antioxidant defence systems, therefore minimal imbalances in the redox state can result in an oxidative environment that favours tissue damage and activates neuroinflammatory processes. Mitochondrial-associated molecular pathways are often compromised in the pathophysiology of neurodegeneration, including the parkin/PINK1, Nrf2, PGC1α, and PPARγ pathways. Impairments to these signalling pathways consequently effect the removal of dysfunctional mitochondria, which has been suggested as contributing to the development of neurodegeneration. Mitochondrial dysfunction prevention has become an attractive therapeutic target, and there are several molecular pathways that can be pharmacologically targeted to remove damaged mitochondria by inducing mitochondrial biogenesis or mitophagy, as well as increasing the antioxidant capacity of the brain, in order to alleviate mitochondrial dysfunction and prevent the development and progression of neurodegeneration in these disorders. Compounds such as natural polyphenolic compounds, bioactive quinones, and Nrf2 activators have been reported in the literature as novel therapeutic candidates capable of targeting defective mitochondrial pathways in order to improve mitochondrial function and reduce the severity of neurodegeneration in these disorders.