Glucagon regulates glucose and lipid metabolism and also promotes weight loss. Thus, therapeutics stimulating glucagon-receptor (GCGR) signaling are promising for obesity treatment; however, the underlying mechanism(s) have yet to be fully elucidated. We previously identified that hepatic GCGR signaling increases circulating Fibroblast Growth Factor 21 (FGF21), a potent regulator of energy balance. We reported that mice deficient for liver Fgf21 are partially resistant to GCGR-mediated weight loss, implicating FGF21 as a regulator of glucagon’s weight-loss effects. FGF21 signaling requires an obligate co-receptor (B-Klotho, KLB), with expression limited to adipose tissue, liver, pancreas, and brain. We hypothesized that the GCGR-FGF21 system mediates weight loss through a central mechanism. Mice deficient for neuronal Klb (Klb∆CNS) exhibit a partial reduction in body weight with chronic GCGR-agonism (via IUB288) compared to controls (p<0.0001), supporting a role for central FGF21 signaling in GCGR-mediated weight loss. Substantiating these results, mice with central KLB inhibition via a pharmacological KLB antagonist (1153) also display partial weight loss (p<0.0001). Central KLB, however, is dispensable for GCGR-mediated improvements in plasma cholesterol and liver triglycerides. Together, these data suggest GCGR-agonism mediates part of its weight loss properties through central KLB and has implications for future treatments against obesity and metabolic syndrome.
Shelly R. Nason, Jessica P. Antipenko, Natalie Presedo, Stephen E. Cunningham, Tanya H. Pierre, Teayoun Kim, Jodi R. Paul, Cassie L. Holleman, Martin E. Young, Karen L. Gamble, Brian Finan, Richard DiMarchi, Chad S. Hunter, Alexei Kharitonenkov, Kirk M. Habegger
Computational models based on recent maps of the red blood cell proteome suggest that mature erythrocytes may harbor targets for common drugs. This prediction is relevant to red blood cell storage in the blood bank, in which the impact of small molecule drugs or other xenometabolites deriving from dietary, iatrogenic or environmental exposures (“exposome”) may alter erythrocyte energy and redox metabolism and, in so doing, affect red cell storage quality and post-transfusion efficacy. To test this prediction, here we provide a comprehensive characterization of the blood donor exposome, including the detection of common prescription and over-the-counter drugs in 250 units donated by healthy volunteers from the REDS-III RBC Omics study. Based on high-throughput drug screenings of 1,366 FDA-approved drugs, we report a significant impact of ~65% of the tested drugs on erythrocyte metabolism. Machine learning models built using metabolites as predictors were able to accurately predict drugs for several drug classes/targets (bisphosphonates, anticholinergics, calcium channel blockers, adrenergics, proton-pump inhibitors, antimetabolites, selective serotonin reuptake inhibitors, and mTOR) suggesting that these drugs have a direct, conserved, and significant impact on erythrocyte metabolism. As a proof of principle, here we show that the antiacid ranitidine – though rarely detected in the blood donor population – has a strong effect on RBC markers of storage quality in vitro. We thus show that ranitidine supplementation to blood units could improve erythrocyte metabolism and storage quality when supplemented to blood bags, through mechanisms involving sphingosine 1-phosphate-dependent modulation of erythrocyte glycolysis and/or direct binding to hemoglobin.
Travis Nemkov, Davide Stefanoni, Aarash Bordbar, Aaron Issaian, Bernhard O. Palsson, Larry J. Dumont, Ariel M. Hay, Anren Song, Yang Xia, Jasmina S. Redzic, Elan Z. Eisenmesser, James C. Zimring, Steve Kleinman, Kirk C. Hansen, Michael Busch, Angelo D’Alessandro
Subjects with obesity frequently have elevated serum vasopressin levels, noted by the stable analog, copeptin. Vasopressin acts primarily to reabsorb water via urinary concentration. However, fat is also a source of metabolic water, raising the possibility that vasopressin might have a role in fat accumulation. Fructose has also been reported to stimulate vasopressin. Here we tested the hypothesis that fructose induced metabolic syndrome is mediated by vasopressin. Orally administered fructose, glucose or high fructose corn syrup increased vasopressin (copeptin) concentrations and was mediated by fructokinase, an enzyme specific for fructose metabolism. Suppressing vasopressin with hydration both prevented and ameliorated fructose-induced metabolic syndrome. The vasopressin effects were mediated by the Vasopressin 1b receptor, as Vasopressin 1b receptor knockout mice were completely protected while V1a knockout paradoxically showed worse metabolic syndrome. The mechanism is likely mediated in part by de novo expression of V1b in the liver that amplifies fructokinase expression in response to fructose. Thus, our studies document a new role for vasopressin in water conservation via the accumulation of fat as a source of metabolic water. Clinically, it also suggests that increased water intake may be a beneficial way to both prevent or treat metabolic syndrome.
Ana Andres-Hernando, Thomas J. Jensen, Masanari Kuwabara, David J. Orlicky, Christina Cicerchi, Nanxing Li, Carlos A. Roncal-Jimenez, Gabriela E. Garcia, Takuji Ishimoto, Paul S. Maclean, Petter Bjornstad, Laura Gabriela Sanchez-Lozada, Mehmet Kanbay, Takahiko Nakagawa, Richard Johnson, Miguel Lanaspa
Limited experimental evidence bridges nutrition and cancer immunosurveillance. Here, we show that ketogenic diet (KD) or its principal ketone body, 3-hydroxybutyrate (3HB), most specifically in an intermittent scheduling, induced T cell-dependent tumor growth retardation of aggressive tumor models. In conditions in which anti-PD-1, alone or in combination with anti-CTLA-4, failed to reduce tumor growth in mice receiving a standard diet, KD or oral supplementation of 3HB reestablished therapeutic responses. Supplementation of KD with sucrose (which breaks ketogenesis, abolishing 3HB production) or with a pharmacological antagonist of the 3HB receptor GPR109A abolished the antitumor effects. Mechanistically, 3HB prevented the ICB-linked upregulation of PD-L1 on myeloid cells while favoring the expansion of CXCR3+ T cells. KD induced compositional changes of the gut microbiota with distinct species such as Eisenbergiella massiliensis commonly emerging in mice and humans subjected to carbohydrate low diet interventions and highly correlating with serum concentrations of 3HB. Altogether, these results demonstrate that KD induces a 3HB-mediated antineoplastic effect that relies on T-cell mediated cancer immunosurveillance.
Gladys Ferrere, Maryam Tidjani Alou, Peng Liu, Anne-Gaëlle Goubet, Marine Fidelle, Oliver Kepp, Sylvère Durand, Valerio Iebba, Aurélie Fluckiger, Romain Daillère, Cassandra Thelemaque, Claudia Grajeda-Iglesias, Carolina Alves Costa Silva, Fanny Aprahamian, Deborah Lefevre, Liwei Zhao, Bernhard Ryffel, Emeline Colomba, Monica Arnedos, Damien Drubay, Conrad Rauber, Didier Raoult, Francesco Asnicar, Tim Spector, Nicola Segata, Lisa Derosa, Guido Kroemer, Laurence Zitvogel.
Extra-pulmonary manifestations of COVID-19 are associated with a much higher mortality rate. Yet, little is known about the pathogenesis of systemic complications of COVID-19. Here, we create a murine model of SARS-CoV-2 induced severe systemic toxicity and multi-organ involvement by expressing the human ACE2 transgene in multiple tissues via viral delivery followed by systemic administration of SARS-CoV-2. The animals develop a profound phenotype within 7 days with severe weight loss, morbidity and failure to thrive. We demonstrate there is metabolic suppression of oxidative phosphorylation and the tri-carboxylic acid (TCA) cycle in multiple organs with neutrophilia, lymphopenia and splenic atrophy mirroring human COVID-19 phenotypes. Animals had a significantly lower heart rate and electron microscopy demonstrated myofibrillar disarray and myocardial edema, a common pathogenic cardiac phenotype in human COVID-19. We perform metabolomic profiling of peripheral blood and identify a panel of TCA cycle metabolites that serve as biomarkers of depressed oxidative phosphorylation. Finally, we observed that SARS-CoV-2 induces epigenetic changes of DNA methylation, that affects expression of immune response genes and could in part contribute to COVID-19 pathogenesis. Our model suggests that SARS-CoV-2 induced metabolic reprogramming and epigenetic changes in internal organs could contribute to systemic toxicity and lethality in COVID-19.
Shen Li, Feiyang Ma, Tomohiro Yokota, Gustavo Garcia Jr., Amelia Palermo, Yijie Wang, Colin Farrell, Yu-Chen Wang, Rimao Wu, Zhiqiang Zhou, Calvin Pan, Marco Morselli, Michael A. Teitell, Sergey Ryazantsev, Gregory A. Fishbein, Johanna ten Hoeve, Valerie A. Arboleda, Joshua Bloom, Barbara J. Dillon, Matteo Pellegrini, Aldons J. Lusis, Thomas G. Graeber, Vaithilingaraja Arumugaswami, Arjun Deb
Enhanced energy expenditure in brown (BAT) and white (WAT) adipose tissues can be therapeutic against metabolic diseases. We examined the thermogenic role of adipose α/β-hydrolase domain-6 (ABHD6), which hydrolyzes monoacylglycerol (MAG), by employing adipose-specific ABHD6-KO mice. Control and KO mice show similar phenotype at room temperature and thermoneutral conditions. However, KO mice are resistant to hypothermia, which can be accounted for by the simultaneously increased lipolysis and lipogenesis of the thermogenic glycerolipid/free fatty acid (GL/FFA) cycle in visceral fat, despite unaltered UCP1 expression. Upon cold-stress, nuclear 2-MAG levels increase in visceral WAT of the KO mice. Evidence is provided that 2-MAG causes activation of PPARα in white adipocytes, leading to elevated expression and activity of GL/FFA cycle enzymes. In the ABHD6-ablated BAT, glucose and oxidative metabolism are elevated upon cold-induction, without changes in GL/FFA cycle and lipid turnover. Moreover, response to in vivo β3-adrenergic stimulation is comparable between KO and control mice. Our data reveal a MAG/PPARα/GL/FFA cycling metabolic signaling network in visceral adipose tissue, which contributes to cold-tolerance, and that adipose ABHD6 is a negative modulator of adaptive thermogenesis.
Pegah Poursharifi, Camille Attané, Yves Mugabo, Anfal Al-Mass, Anindya Ghosh, Clémence Schmitt, Shangang Zhao, Julian Guida, Roxane Lussier, Heidi Erb, Isabelle Chenier, Marie-Line Peyot, Erik Joly, Christophe Noll, André C. Carpentier, S.R. Murthy Madiraju, Marc Prentki
Background Severe acute malnutrition (SAM) is a major contributor to global mortality in children under 5 years. Mortality has decreased, however the long-term cardiometabolic consequences of SAM and its subtypes, severe wasting (SW) and edematous malnutrition (EM), are not well understood. We evaluated the metabolic profiles of adult SAM survivors using targeted metabolomic analyses. Methods This cohort study of 122 adult SAM survivors (SW=69, EM=53) and 90 age, sex and BMI-matched community participants (CPs) quantified serum metabolites using direct flow injection mass spectrometry combined with reverse-phase liquid chromatography. Univariate and sparse partial least square discriminant analyses (sPLS-DA) assessed differences in metabolic profiles and identified the most discriminative metabolites. Results 77 metabolite variables were significant in distinguishing between SAM survivors (28.4 ± 8.8 years, 24.0 ± 6.1 kg/m2) and CPs (28.4 ± 8.9 years, 23.3 ± 4.4 kg/m2) (mean ± SDs) in univariate and sPLS-DA models. Compared to CPs, SAM survivors had less liver fat, higher branched-chained amino acids (BCAAs), urea cycle metabolites and kynurenine-tryptophan (KT) ratio (p<0.001) and lower β-hydroxybutyric acid and acylcarnitine:free carnitine ratio (p<0.001) which were both associated with hepatic steatosis (p<0.001). SW and EM survivors had similar metabolic profiles as did stunted and non-stunted SAM survivors. Conclusions Adult SAM survivors have distinct metabolic profiles that suggest reduced β-oxidation and greater risk of type 2 diabetes (BCAAs, KT ratio, urea cycle metabolites) compared to community participants. This indicates that early childhood SAM exposure has long-term metabolic consequences that may worsen with age and require targeted clinical management. Funding Health Research Council of New Zealand Caribbean Public Health Agency Centre for Global Child Health, Hospital for Sick Children. DST is an Academic Fellow and a Restracomp Fellow at the Centre for Global Child Health GBG is a postdoctoral fellow of the Research Foundation Flanders (FWO).
Debbie S. Thompson, Celine Bourdon, Paraskevi Massara, Michael S. Boyne, Terrence Forrester, Gerard Bryan Gonzales, Robert HJ Bandsma
Non-alcoholic fatty liver disease (NAFLD) is characterized by hepatic lipid accumulation. The transmembrane 6 superfamily member 2 (TM6SF2) E167K genetic variant associates with NAFLD and with reduced plasma triglyceride levels in humans. However, the molecular mechanisms underlying these associations remain unclear. We hypothesized that TM6SF2 E167K affects hepatic very low-density lipoprotein (VLDL) secretion, and studied the kinetics of apolipoprotein B100 (apoB100) and triglyceride metabolism in VLDL in homozygous subjects. In 10 homozygote TM6SF2 E167K carriers and 10 matched controls, we employed stable-isotope tracer and compartmental modeling techniques to determine apoB100 and triglyceride kinetics in the two major VLDL subfractions: large triglyceride-rich VLDL1 and smaller, less triglyceride-rich VLDL2. VLDL1-apoB100 production was markedly reduced in homozygote TM6SF2 E167K carriers compared to controls. Likewise, VLDL1-triglyceride production was 35% lower in the TM6SF2 E167K carriers. In contrast, the direct production rates for VLDL2-apoB100 and triglyceride were not different between carriers and controls. In conclusion, the TM6SF2 E167K genetic variant was linked to a specific reduction in hepatic secretion of large triglyceride-rich VLDL1. The impaired secretion of VLDL1 explains the reduced plasma triglyceride concentration, and provides a basis for understanding the lower risk of cardiovascular disease associated with the TM6SF2 E167K genetic variant. Trial registration: Clinical Trials NCT04209816
Jan Borén, Martin Adiels, Elias Björnson, Niina Matikainen, Sanni Söderlund, Joel T. Rämo, Marcus Ståhlman, Pietari Ripatti, Samuli Ripatti, Aarno Palotie, Rosellina M. Mancina, Antti Hakkarainen, Stefano Romeo, Chris J. Packard, Marja-Riitta Taskinen
Diabetic kidney disease (DKD) is the most common cause of severe renal disease worldwide and the single strongest predictor of mortality in diabetes patients. Kidney steatosis has emerged as a critical trigger in the pathogenesis of DKD; however, the molecular mechanism of renal lipotoxicity remains largely unknown. Our recent studies in genetic mouse models, human cell lines, and well-characterized patient cohorts have identified serine/threonine protein kinase (STK)25 as a critical regulator of ectopic lipid storage in several metabolic organs prone to diabetic damage. Here, we demonstrate that overexpression of STK25 aggravates renal lipid accumulation and exacerbates structural and functional kidney injury in a mouse model of DKD. Reciprocally, inhibiting STK25 signaling in mice ameliorates diet-induced renal steatosis and alleviates the development of DKD-associated pathologies. Further, we find that STK25 silencing in human kidney cells protects against lipid deposition as well as oxidative and endoplasmic reticulum stress. Together, our results suggest that STK25 regulates a critical node governing susceptibility to renal lipotoxicity and that STK25 antagonism could mitigate DKD progression.
Emmelie Cansby, Mara Caputo, Lei Gao, Nagaraj M. Kulkarni, Annika Nerstedt, Marcus Ståhlman, Jan Boren, Rando Porosk, Ursel Soomets, Matteo Pedrelli, Paolo Parini, Hanns-Ulrich Marschall, Jenny Nyström, Brian W. Howell, Margit Mahlapuu
Diabetic neuropathy is a major complication of diabetes. Current treatment options alleviate pain but do not stop the progression of the disease. At present, there are no approved disease-modifying therapies. Thus, developing more effective therapies remains a major unmet medical need. Seeking to better understand the molecular mechanisms driving peripheral neuropathy, as well as other neurological complications associated with diabetes, we performed spatiotemporal lipidomics, biochemical, ultrastructural, and physiological studies on PNS and CNS tissue from multiple diabetic preclinical models. We unraveled potentially novel molecular fingerprints underlying nerve damage in obesity-induced diabetes, including an early loss of nerve mitochondrial (cardiolipin) and myelin signature (galactosylceramide, sulfatide, and plasmalogen phosphatidylethanolamine) lipids that preceded mitochondrial, myelin, and axonal structural/functional defects; started in the PNS; and progressed to the CNS at advanced diabetic stages. Mechanistically, we provided substantial evidence indicating that these nerve mitochondrial/myelin lipid abnormalities are (surprisingly) not driven by hyperglycemia, dysinsulinemia, or insulin resistance, but rather associate with obesity/hyperlipidemia. Importantly, our findings have major clinical implications as they open the door to novel lipid-based biomarkers to diagnose and distinguish different subtypes of diabetic neuropathy (obese vs. nonobese diabetics), as well as to lipid-lowering therapeutic strategies for treatment of obesity/diabetes-associated neurological complications and for glycemic control.
Juan P. Palavicini, Juan Chen, Chunyan Wang, Jianing Wang, Chao Qin, Eric Baeuerle, Xinming Wang, Jung A. Woo, David E. Kang, Nicolas Musi, Jeffrey L. Dupree, Xianlin Han
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