Metabolisms
Abstract
Muscle weakness and wasting are defining features of cancer-induced cachexia. Mitochondrial stress occurs before atrophy in certain muscles, but the possibility of heterogeneous responses between muscles and across time remains unclear. Using mice inoculated with Colon-26 (C26) cancer, we demonstrate that specific force production was reduced in quadriceps and diaphragm at 2 weeks in the absence of atrophy. At this time, pyruvate-supported mitochondrial respiration was lower in quadriceps while mitochondrial H2O2 emission was elevated in diaphragm. By 4 weeks, atrophy occurred in both muscles, but specific force production increased to control levels in quadriceps such that reductions in absolute force were due entirely to atrophy. Specific force production remained reduced in diaphragm. Mitochondrial respiration increased and H2O2 emission was unchanged in both muscles vs control while mitochondrial creatine sensitivity was reduced in quadriceps. These findings indicate muscle weakness precedes atrophy and is linked to heterogeneous mitochondrial alterations that could involve adaptive responses to metabolic stress. Eventual muscle-specific restorations in force and bioenergetics highlight how the effects of cancer on one muscle do not predict the response in another muscle. Exploring heterogeneous responses of muscle to cancer may reveal new mechanisms underlying distinct sensitivities, or resistance, to cancer cachexia.
Authors
Luca J. Delfinis, Catherine A. Bellissimo, Shivam Gandhi, Sara N. DiBenedetto, Madison C. Garibotti, Arshdeep K. Thuhan, Stavroula Tsitkanou, Megan E. Rosa-Caldwell, Fasih A. Rahman, Arthur J. Cheng, Michael P. Wiggs, Uwe Schlattner, Joe Quadrilatero, Nicholas P. Greene, Christopher G.R. Perry
Abstract
Acute lung injury (ALI) is a severe form of lung inflammation causing acute respiratory distress syndrome in patients. ALI pathogenesis is closely linked to uncontrolled alveolar inflammation. We hypothesize that specific enzymes of the glycolytic pathway could function as key regulators of alveolar inflammation. Therefore, we screened isolated alveolar epithelia from mice exposed to ALI induced by injurious ventilation to assess their metabolic responses. These studies pointed us towards a selective role for isoform 3 of the 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3). Pharmacologic inhibition or genetic deletion of Pfkfb3 in alveolar epithelia (Pfkfb3loxp/loxp SPC-ER-Cre+ mice) was associated with profound increases in ALI during injurious mechanical ventilation or acid installation. Studies in genetic models linked Pfkfb3 expression and function to hypoxia-inducible factor Hif1a. Intra-tracheal pyruvate instillation not only reconstituted Pfkfb3loxp/loxp or Hif1aloxp/loxp SPC ER Cre+ mice, but pyruvate was also effective in ALI treatment of wild-type mice. Finally, proof-of-principle studies in human lung biopsies confirmed increased PFKFB3 staining in injured lungs and co-localized PFKFB3 to alveolar epithelia. These studies reveal a specific role for PFKFB3 in counter-balancing alveolar inflammation and lay the groundwork for novel metabolic therapeutic approaches during ALI.
Authors
Christine U. Vohwinkel, Nana Burns, Ethan Coit, Xiaoyi Yuan, Eszter K. Vladar, Christina Sul, Eric P. Schmidt, Peter Carmeliet, Kurt Stenmark, Eva S. Nozik, Rubin M. Tuder, Holger K. Eltzschig
Abstract
Dihydrolipoamide dehydrogenase (DLD) deficiency is a recessive mitochondrial disorder caused by depletion of DLD from α-ketoacid dehydrogenase complexes. Caenorhabditis elegans animal models of DLD deficiency generated by graded feeding of dld-1(RNAi) revealed that full or partial reduction of DLD-1 expression recapitulated increased pyruvate levels typical of pyruvate dehydrogenase complex deficiency and significantly altered animal survival and health, with reductions in brood size, adult length, and neuromuscular function. DLD-1 deficiency dramatically increased mitochondrial unfolded protein stress response induction and adaptive mitochondrial proliferation. While ATP levels were reduced, respiratory chain enzyme activities and in vivo mitochondrial membrane potential were not significantly altered. DLD-1 depletion directly correlated with the induction of mitochondrial stress and impairment of worm growth and neuromuscular function. The safety and efficacy of dichloroacetate, thiamine, riboflavin, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), l-carnitine, and lipoic acid supplemental therapies empirically used for human DLD disease were objectively evaluated by life span and mitochondrial stress response studies. Only dichloroacetate and thiamine showed individual and synergistic therapeutic benefits. Collectively, these C. elegans dld-1(RNAi) animal model studies demonstrate the translational relevance of preclinical modeling of disease mechanisms and therapeutic candidates. Results suggest that clinical trials are warranted to evaluate the safety and efficacy of dichloroacetate and thiamine in human DLD disease.
Authors
Chynna N. Broxton, Prabhjot Kaur, Manuela Lavorato, Smruthi Ganesh, Rui Xiao, Neal D. Mathew, Eiko Nakamaru-Ogiso, Vernon E. Anderson, Marni J. Falk
Abstract
Rosacea is a chronic skin disorder characterized by abnormal neurovascular and inflammatory conditions on the central face. Despite increasing evidence suggests that rosacea is associated with metabolic disorders, the role of metabolism in rosacea pathogenesis remains unknown. Here, via targeted metabolomics approach, we characterized significantly altered metabolic signatures in rosacea patients, especially for amino acid-related metabolic pathways. Among these, glutamic acid and aspartic acid are highlighted and positively correlated with the disease severity in rosacea patients. We further demonstrated that glutamic acid and aspartic acid can facilitate the development of erythema and telangiectasia, typical features of rosacea, in the skin of mice. Mechanistically, glutamic acid and aspartic acid stimulate the production of vasodilation-related neuropeptides from peripheral neuron and keratinocytes, and induce the release of nitric oxide from endothelial cells and keratinocytes. Interestingly, we provided evidence showing that doxycycline can improve the symptoms of rosacea patients possibly by targeting amino acid metabolic pathway. These findings reveal that abnormal amino acid metabolism promotes neurovascular reactivity in rosacea, and raise the possibility of targeting dysregulated metabolism as a promising strategy for clinical treatment.
Authors
Tangxiele Liu, Wenqin Xiao, Mengting Chen, Rui Mao, San Xu, Qinqin Peng, Zhixiang Zhao, Qian Wang, Hongfu Xie, Zhili Deng, Ji Li
Abstract
BACKGROUND Insulin resistance of the brain can unfavorably affect long-term weight maintenance and body fat distribution. Little is known if and how brain insulin sensitivity can be restored in humans. We aimed to evaluate the effects of an exercise intervention on insulin sensitivity of the brain and how this relates to exercise-induced changes in whole-body metabolism and behavior.METHODS In this clinical trial, sedentary participants who were overweight and obese underwent an 8-week supervised aerobic training intervention. Brain insulin sensitivity was assessed in 21 participants (14 women, 7 men; age range 21–59 years; BMI range 27.5–45.5 kg/m2) using functional MRI, combined with intranasal administration of insulin, before and after the intervention.RESULTS The exercise program resulted in enhanced brain insulin action to the level of a person of healthy weight, demonstrated by increased insulin-induced striatal activity and strengthened hippocampal functional connectivity. Improved brain insulin action correlated with increased mitochondrial respiration in skeletal muscle, reductions in visceral fat and hunger, as well as improved cognition. Mediation analyses suggest that improved brain insulin responsiveness helps mediate the peripheral exercise effects leading to healthier body fat distribution and reduced perception of hunger.CONCLUSION Our study demonstrates that an 8-week exercise intervention in sedentary individuals can restore insulin action in the brain. Hence, the ameliorating benefits of exercise toward brain insulin resistance may provide an objective therapeutic target in humans in the challenge to reduce diabetes risk factors.TRIAL REGISTRATION ClinicalTrials.gov (NCT03151590).FUNDING BMBF/DZD 01GI0925.
Authors
Stephanie Kullmann, Thomas Goj, Ralf Veit, Louise Fritsche, Lore Wagner, Patrick Schneeweiss, Miriam Hoene, Christoph Hoffmann, Jürgen Machann, Andreas Niess, Hubert Preissl, Andreas L. Birkenfeld, Andreas Peter, Hans-Ulrich Häring, Andreas Fritsche, Anja Moller, Cora Weigert, Martin Heni
Abstract
Obesity-induced asthma responds poorly to all current pharmacological interventions, including steroids; suggesting that classic, eosinophilic inflammation is not a mechanism. As insulin resistance and hyperinsulinemia are common in obese individuals and associated with increased risk of asthma, we used diet-induced obese mice to study how insulin induces airway hyperreactivity. Inhaled 5-HT or methacholine induced dose dependent bronchoconstriction that was significantly potentiated in obese mice. Cutting the vagus nerves eliminated bronchoconstriction in both obese and non-obese animals indicating it was mediated by a neural reflex. There was significantly greater density of airway sensory nerves in obese than in non-obese mice. Deleting insulin receptors on sensory nerves prevented the increase in sensory nerve density and prevented airway hyperreactivity in obese mice with hyperinsulinemia. Our data demonstrate that high levels of insulin drives obesity-induced airway hyperreactivity by increasing sensory innervation of the lung. Therefore, pharmacological interventions to control metabolic syndrome and limit reflex-mediated bronchoconstriction may be a more effective approach to reduce asthma exacerbations in obese and asthmatic patients.
Authors
Gina N. Calco, Jessica N. Maung, David B. Jacoby, Allison D. Fryer, Zhenying Nie
Abstract
Puberty is associated with transient insulin resistance that normally recedes at the end of puberty; however, in overweight children insulin resistance persists leading to an increased risk of type 2 diabetes. The mechanisms whereby pancreatic β cells adapt to pubertal insulin resistance, and how they are affected by the metabolic status, have not been investigated. Here we show that puberty is associated with a transient increase in β-cell proliferation in rats and humans of both sexes. In rats, β-cell proliferation correlated with a rise in growth hormone (GH) levels. Serum from pubertal rats and humans promoted β-cell proliferation, suggesting the implication of a circulating factor. In pubertal rat islets, expression of genes of the GH/serotonin (5-HT) pathway underwent changes consistent with proliferative effect. Inhibition of the pro-proliferative 5-HT receptor isoform HTR2B blocked the increase in β-cell proliferation in pubertal islets ex vivo and in vivo. Peri-pubertal metabolic stress blunted β-cell proliferation during puberty and led to altered glucose homeostasis later in life. This study identifies a role of GH/GHR/5-HT/HTR2B signaling in the control of β-cell mass expansion during puberty and a mechanistic link between pubertal obesity and the risk of developing type 2 diabetes.
Authors
Anne-Laure Castell, Clara Goubault, Mélanie Ethier, Grace Fergusson, Caroline Tremblay, Marie Baltz, Dorothée Dal Soglio, Julien Ghislain, Vincent Poitout
Abstract
BACKGROUND. Apolipoprotein CIII is a regulator of triglyceride (TG) metabolism, and due to its association with risk of cardiovascular disease, is an emergent target for pharmacological intervention. The impact of substantially lowering apoC-III on lipoprotein metabolism is not clear. METHODS. We investigated the kinetics of apolipoproteins B48 and B100 in chylomicrons, VLDL1, VLDL2, IDL and LDL in subjects heterozygous for a loss-of-function (LOF) mutation in the APOC3 gene. Studies were conducted in the post-prandial state to provide a more comprehensive view of the influence of this protein on TG transport. RESULTS. Compared to non-LOF subjects, a genetically-determined decrease in apoC-III resulted in marked acceleration of lipolysis of triglyceride-rich lipoproteins (TRL), increased removal of VLDL remnants from the bloodstream, and a substantial decrease in circulating levels of VLDL1, VLDL2 and IDL particles. Production rates for apolipoprotein B48-containing chylomicrons and apoB100-containing VLDL1 and VLDL2 were not different between LOF carriers and non-carriers. Likewise, the rate of production of LDL was not affected by the lower apoC-III level, nor was the concentration of LDL-apoB100 or its clearance rate. CONCLUSION. These findings indicate that apoC-III lowering will have a marked effect on TRL and remnant metabolism, with possibly significant consequences for cardiovascular disease prevention. TRIAL REGISTRATIONS. Clinical Trials NCT04209816 and NCT01445730 FUNDING. This project was funded by grants from Swedish Heart-Lung Foundation, Swedish Research Council, ALF grant from the Sahlgrenska University Hospital, Novo Nordisk Foundation, Sigrid Juselius Foundation, Helsinki University Hospital Government Research funds, Finnish Heart Foundation, and Finnish Diabetes Research Foundation.
Authors
Marja-Riitta Taskinen, Elias Björnson, Niina Matikainen, Sanni Söderlund, Joel Rämo, Mari-Mia Ainola, Antti Hakkarainen, Carina Sihlbom, Annika Thorsell, Linda Andersson, Per-Olof Bergh, Marcus Henricsson, Stefano Romeo, Martin Adiels, Samuli Ripatti, Markku Laakso, Chris J. Packard, Jan Borén
Abstract
Obesity is an important risk factor for atrial fibrillation (AF), but a better mechanistic understanding of obesity-related atrial fibrillation is required. Serum glucocorticoid kinase 1 (SGK1) is a kinase positioned within multiple obesity-related pathways, and prior work has shown a pathologic role of SGK1 signaling in ventricular arrhythmias. We validated a mouse model of obesity-related AF using wild type mice fed a high fat diet. RNA sequencing of atrial tissue demonstrated substantial differences in gene expression, with enrichment of multiple SGK1-related pathways, and we confirmed upregulated of SGK1 transcription, activation, and signaling in obese atria. Mice expressing a cardiac specific dominant negative SGK1 were protected from obesity-related AF, through effects on atrial electrophysiology, action potential characteristics, structural remodeling, inflammation, and sodium current. Overall, this study demonstrates the promise of targeting SGK1 in a mouse model of obesity-related AF.
Authors
Aneesh Bapat, Guoping Li, Ling Xiao, Ashish Yeri, Maarten Hulsmans, Jana Grune, Masahiro Yamazoe, Maximillian J. Schloss, Yoshiko Iwamoto, Justin G. Tedeschi, Xinyu Yang, Matthias Nahrendorf, Anthony Rosenzweig, Patrick T. Ellinor, Saumya Das, David Milan
Abstract
Immune checkpoint blockade (ICB) therapy has achieved breakthroughs in the treatment of advanced non-small cell lung cancer (NSCLC). Nevertheless, the low response due to immuno-cold tumor microenvironment (TME) largely limits the application of ICB therapy. Based on the glycolytic/cholesterol synthesis axis, a stratification framework for EGFR wild-type NSCLC was developed to summarize the metabolic features of immuno-cold and immuno-hot tumors. The cholesterol subgroup displays the worst prognosis in immuno-cold NSCLC with significant enrichment of the cholesterol gene signature, indicating targeting cholesterol synthesis is essential for the therapy for immuno-cold NSCLC. Statin, the inhibitor for cholesterol synthesis, can suppress the aggressiveness of NSCLC in vitro and in vivo and also drastically reverse immuno-cold to an inflamed phenotype in vivo which exhibited a higher response to ICB therapy. Moreover, both our in-house data and meta-analysis further support that statin can significantly enhance ICB efficacy. In terms of preliminary mechanisms, statin could transcriptionally inhibit PD-L1 expression and induce ferroptosis in NSCLC cells. Overall, we reveal the significance of cholesterol synthesis in NSCLC and demonstrate the improved therapeutic efficacy of ICB in combination with statin. These findings could provide a innovative clinical insight to treat NSCLC patients with immuno-cold tumors.
Authors
Wenjun Mao, Yun Cai, Danrong Chen, Guanyu Jiang, Yongrui Xu, Ruo Chen, Fengxu Wang, Xuehai Wang, Mingfeng Zheng, Xinyuan Zhao, Jie Mei
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