Research Article
Abstract
A single bout of exercise improves muscle insulin sensitivity for up to 48 hours via AMPK. Limb ischemia activates AMPK in muscle, and subsequent reperfusion enhances insulin-stimulated vasodilation, potentially eliciting a more pronounced exercise effect with reduced workload. We investigated the combined effect of upper leg intermittent ischemia/reperfusion (IIR) and continuous knee-extension exercise on muscle insulin sensitivity regulation. We found that IIR exercise potentiated AMPK activation and muscle insulin sensitivity. The potentiating effect of IIR exercise on muscle insulin sensitivity was associated with increased insulin-stimulated blood flow in parallel with enhanced phosphorylation of endothelial nitric oxide synthase. Metabolomics analyses demonstrated a suppression of muscle medium-chain acylcarnitines during IIR exercise, which correlated with insulin sensitivity and was consistent with findings in isolated rat muscle treated with decanoyl-l-carnitine. Collectively, combining IIR with low- to moderate-intensity exercise may represent a promising intervention to effectively enhance muscle insulin sensitivity. This approach could offer potential for mitigating muscle insulin resistance in clinical settings and among individuals with lower physical activity levels.
Authors
Kohei Kido, Janne R. Hingst, Johan Onslev, Kim A. Sjøberg, Jesper B. Birk, Nicolas O. Eskesen, Tongzhu Zhou, Kentaro Kawanaka, Jesper F. Havelund, Nils J. Færgeman, Ylva Hellsten, Jørgen F.P. Wojtaszewski, Rasmus Kjøbsted
Abstract
Treatment options for advanced liver disease and hepatocellular carcinoma (HCC) are limited, and strategies to prevent HCC development are lacking. Aiming to discover therapeutic targets, we combined genome-wide transcriptomic analysis of liver tissues from patients with advanced liver disease and HCC and a cell-based system predicting liver disease progression and HCC risk. Computational analysis predicted peroxiredoxin 2 (PRDX2) as a candidate gene mediating hepatocarcinogenesis and HCC risk. Analysis of tissues from patients with HCC confirmed a perturbed expression of PRDX2 in cancer. In vivo perturbation studies in mouse models for hepatocarcinogenesis driven by metabolic dysfunction–associated steatohepatitis showed that specific Prdx2 KO in hepatocytes improved metabolic liver functions, restored AMPK activity, and prevented HCC development by suppressing oncogenic signaling. Perturbation studies in HCC cell lines, a cell line–derived xenograft mouse model, and patient-derived HCC spheroids revealed that PRDX2 also mediates cancer initiation, cancer cell proliferation, and survival through its antioxidant activity. Targeting PRDX2 may therefore be a strategy to prevent HCC development in metabolic liver disease.
Authors
Emilie Crouchet, Eugénie Schaeffer, Marine A. Oudot, Julien Moehlin, Cloé Gadenne, Frank Jühling, Hussein El Saghire, Naoto Fujiwara, Shijia Zhu, Fahmida Akter Rasha, Sarah C. Durand, Anouk Charlot, Clara Ponsolles, Romain Martin, Nicolas Brignon, Fabio Del Zompo, Laura Meiss-Heydmann, Marie Parnot, Nourdine Hamdane, Danijela Heide, Jenny Hetzer, Mathias Heikenwälder, Emanuele Felli, Patrick Pessaux, Nathalie Pochet, Joffrey Zoll, Brian Cunniff, Yujin Hoshida, Laurent Mailly, Thomas F. Baumert, Catherine Schuster
Abstract
Allergic diseases have reached epidemic proportions globally, calling attention to the need for better treatment and preventive approaches. Herein, we developed allergen-encoding messenger RNA (mRNA)–lipid nanoparticle (LNP) strategies for both therapy and prevention of allergic responses. Immunization with allergen-encoded mRNA-LNPs modulated T cell differentiation, inhibiting the generation of T helper type 2 and type 17 cells upon allergen exposure in experimental asthma models induced by ovalbumin, and naturally occurring house dust mite (HDM) and the major HDM allergen Der p1. Allergen-specific mRNA-LNP treatment attenuated clinicopathology in both preventive and established allergy models, including reduction in eosinophilia, mucus production, and airway hypersensitivity, while enhancing production of allergen-specific IgG antibodies and maintaining low IgE levels. Additionally, allergen-specific mRNA-LNP vaccines in mice elicited a CD8+CD38+KLRG– T cell response as seen following SARS-CoV-2 mRNA vaccination in humans, underscoring a conserved immune mechanism across species, regardless of the mRNA-encoded protein. Notably, mRNA-LNP vaccination in combination with an mTOR inhibitor reduced the CD8+ T cell response without affecting the vaccine-induced anti-allergic effect in the preventive model of asthma. This technology renders allergen-specific mRNA-LNP therapy a promising approach for prevention and treatment of allergic diseases.
Authors
Yrina Rochman, Michael Kotliar, Andrea M. Klingler, Mark Rochman, Mohamad-Gabriel Alameh, Jilian R. Melamed, Garrett A. Osswald, Julie M. Caldwell, Jennifer M. Felton, Lydia E. Mack, Julie Hargis, Ian P. Lewkowich, Artem Barski, Drew Weissman, Marc E. Rothenberg
Abstract
Through a combination of single-cell/single-nucleus RNA-Seq (sc/snRNA-Seq) data analysis, immunohistochemistry, and primary macrophage studies, we have identified pathogenic macrophages characterized by Tet methylcytosine dioxygenase 3 (TET3) overexpression (Toe-Macs) in 3 major human diseases associated with chronic inflammation: metabolic dysfunction–associated steatohepatitis (MASH), non–small cell lung cancer (NSCLC), and endometriosis. These macrophages are induced by common factors present in the disease microenvironment (DME). Crucially, the universal reliance on TET3 overexpression among these macrophages enabled their selective elimination as a single population, irrespective of heterogeneity in other molecular markers. In mice, depleting these macrophages via myeloid-specific Tet3 KO markedly mitigated disease progression, and the therapeutic effects were recapitulated pharmacologically using a TET3-specific small-molecule degrader. Through an unexpected mode of action, TET3 epigenetically regulated the expression of multiple genes key to the generation and maintenance of an inflammatory/immunosuppressive DME. We propose that Toe-Macs are a unifying feature of pathogenic macrophages that could be therapeutically targeted to treat MASH, NSCLC, endometriosis, and potentially other chronic inflammatory diseases.
Authors
Beibei Liu, Yangyang Dai, Zixin Wang, Jiahui Song, Yushu Du, Haining Lv, Stefania Bellone, Yang-Hartwich Yang, Andrew Kennedy, Songying Zhang, Muthukumaran Venkatachalapathy, Yulia Surovtseva, Penghua Wang, Gordon G. Carmichael, Hugh S. Taylor, Xuchen Zhang, Da Li, Yingqun Huang
Abstract
The role of endothelial dysfunction in tubulointerstitial fibrosis associated with chronic kidney disease (CKD) is not well understood. In this study, we demonstrate that the activation of the endothelial tyrosine kinase TIE2 alleviates renal pathology in experimental CKD in mice. TIE2 activation was achieved using a human angiopoietin-2–binding and TIE2-activating antibody (ABTAA) or through adult-induced endothelium-specific knockout of the vascular endothelial protein tyrosine phosphatase gene (Veptp). Both methods markedly protected CKD mice from endothelial dysfunction, peritubular capillary loss, tubular epithelial injury, and tubulointerstitial fibrosis. Conversely, silencing TIE2 through adult-induced endothelium-specific knockout of the Tie2 gene exacerbated CKD pathology. Additionally, we found that endothelial dysfunction promoted renal fibrosis not through endothelial-to-mesenchymal transition, as previously expected, but by inducing the expression of profibrotic PDGFB in tubular epithelial cells, a process that is inhibited by TIE2 activation. Our findings suggest that TIE2 activation via ABTAA warrants investigation as a therapy in human CKD, where there is a substantial unmet medical need.
Authors
Riikka Pietilä, Amanda Marks-Hultström, Liqun He, Sami Nanavazadeh, Susan E. Quaggin, Christer Betsholtz, Marie Jeansson
Abstract
The persistent challenge of sepsis-related mortality underscores the necessity for deeper insights. Our multicenter, cross-age cohort study identified insulin-like growth factor binding protein 6 (IGFBP6) as a critical regulator in sepsis diagnosis, prognosis, and mortality risk evaluation. Mechanistically, IGFBP6 engages in IGF-independent binding to prohibitin2 (PHB2) on epithelial cells, driving PHB2 tyrosine phosphorylation during sepsis. This process disrupts STAT1 phosphorylation, nuclear translocation, and its recruitment to the CCL2 promoter, ultimately impairing CCL2 transcription and macrophage chemotaxis. Crucially, PHB2 silencing via siPHB2 and STAT1 activation using 2-NP restored CCL2 expression in vitro and in vivo, improving bacterial clearance and survival in septic mice. Concurrently, IGFBP6 compromised macrophage bactericidal activity by inhibiting Akt phosphorylation, reducing ROS/IL-1β production and phagocytic capacity — defects reversible by Akt agonist SC79. Collectively, IGFBP6 emerges as an endogenous driver of sepsis pathogenesis, positioning it as a dual diagnostic biomarker and therapeutic target. Intervention strategies targeting IGFBP6-mediated signaling may offer transformative approaches for sepsis management.
Authors
Kai Chen, Ying Hu, Xiaoyan Yu, Hong Tang, Yanting Ruan, Yue Li, Xun Gao, Qing Zhao, Hong Wang, Xuemei Zhang, David Paul Molloy, Yibing Yin, Dapeng Chen, Zhixin Song
Abstract
Molnupiravir is an antiviral medicine that induces lethal copying errors during SARS-CoV-2 RNA replication. Molnupiravir reduced hospitalization in one pivotal trial by 50% and had variable effects on reducing viral RNA levels in three separate trials. We used mathematical models to simulate these trials and closely recapitulated their virologic outcomes. Model simulations suggested lower antiviral potency against pre-Omicron SARS-CoV-2 variants than against Omicron. We estimated that in vitro assays underestimated in vivo potency by 6- to 7-fold against Omicron variants. Our model suggested that because polymerase chain reaction detects molnupiravir mutated variants, the true reduction in non-mutated viral RNA was underestimated by approximately 0.4 log10 in the two trials conducted while Omicron variants dominated. Viral area under the curve estimates differed significantly between non-mutated and mutated viral RNA. Our results reinforce past work suggesting that in vitro assays are unreliable for estimating in vivo antiviral drug potency and suggest that virologic endpoints for respiratory virus clinical trials should be catered to the drug mechanism of action.
Authors
Shadisadat Esmaeili, Katherine Owens, Ugo Avila-Ponce de Leon, Joseph F. Standing, David M. Lowe, Shengyuan Zhang, James A. Watson, William H.K. Schilling, Jessica Wagoner, Stephen J. Polyak, Joshua T. Schiffer
Abstract
Both adipocytes and hepatocytes have the capacity to store fat, but the factor(s) that determine fat distribution between these cell types remain unknown. In mice fed a high-fat diet, fat initially accumulates predominantly in adipocytes, while hepatic fat accumulation mainly emerges after the onset of epididymal adipocyte death that results in elevated free fatty acids to promote lipid accumulation in hepatocytes. However, it remains unclear whether other signals after adipocyte death are required to direct and/or promote hepatocytes to store fat and subsequently trigger metabolic dysfunction–associated steatotic liver disease (MASLD, formerly known as nonalcoholic fatty liver disease). Using genetically modified mouse models combined with bulk and single-cell RNA-Seq analysis, we demonstrated that visceral adipocyte death induced an accumulation of S100A8+ macrophages in the liver, which was partially induced by fatty acids and apoptotic adipocyte–derived extracellular vesicles. Macrophage-specific deletion of the S100a8 gene reduced hepatic fat accumulation and MASLD severity in mice. Mechanistically, S100A8+ macrophages suppressed cellular communication network factor 3 (CCN3), a negative regulator of CD36, thereby enhancing CD36 expression in hepatocytes. In conclusion, adipocyte death promotes hepatic infiltration of S100A8+ macrophages, which drive hepatocyte lipid storage and subsequently promote MASLD progression through CD36 upregulation, partially mediated by CCN3 suppression.
Authors
Yukun Guan, Yeonsoo Kim, Yang Wang, Ye Eun Cho, Xiaogang Xiang, Seung-Jin Kim, Tiantian Yao, Dechun Feng, Seonghwan Hwang, Bin Gao
Abstract
Solute carrier (SLC) transporters govern the selective transport of diverse molecules across cell membranes, controlling fundamental metabolic and cellular processes. Despite genetic evidence implicating SLC transporters in a variety of human diseases, this family of proteins represents an underexplored target class for therapeutic drug discovery. Here, we discovered a selective potentiator of SLC39A8, a metal transporter associated with inflammatory bowel disease, schizophrenia, and cardiovascular and metabolic disorders. We conducted a drug repurposing screen, identifying efavirenz as a potentiator of manganese and cadmium uptake by SLC39A8 and subsequently generated structure-activity relationships to guide design of analogs. Computational pocket identification methodology and molecular dynamic simulations revealed a ligandable, cryptic pocket that, together with functional mutagenesis, indicated direct target engagement and allosteric modulation. Our findings demonstrate how the combination of experimental data and computational tools represents a powerful synergy that can enhance scientific outcomes. This integrated approach allowed for iterative feedback where insights from experiments informed the model refinements and computational predictions guided future experimental designs. Furthermore, our data established that SLC39A8 transporter activity can be increased pharmacologically, potentially opening avenues for SLC transporter drug discovery.
Authors
Kelly L. Damm-Ganamet, Clara Moon, Alan D. Wickenden, Mark Tichenor, Yunhui Ge, Eduardo V. Mercado-Marin, Brian Chiou, Ayla Manughian-Peter, Taraneh Mirzadegan, Jennifer D. Venable, Ramnik J. Xavier, Jennifer E. Towne, Daniel B. Graham, Jacqueline Perrigoue
Abstract
Sulfite oxidase (SOX) deficiency is a rare inborn error of cysteine metabolism resulting in severe neurological damage. In patients, sulfite accumulates to toxic levels, causing a rise in the downstream products S-sulfocysteine, which mediates excitotoxicity, and thiosulfate, a catabolic intermediate/product of hydrogen sulfide (H2S) metabolism. Here, we report a full-body knockout mouse model for SOX deficiency (SOXD) with a severely impaired phenotype. Among the urinary biomarkers, thiosulfate showed a 45-fold accumulation in SOXD mice, representing the major excreted S-metabolite. Consistently, we found increased plasma H2S, which was derived from sulfite-induced release from persulfides, as demonstrated in vitro and in vivo. Mass spectrometry analysis of total protein persulfidome identified a major loss of S-persulfidation in 20% of the proteome, affecting enzymes in amino acids, fatty acid metabolism, and cytosolic iron-sulfur cluster biogenesis. Urinary amino acid profiles indicated metabolic rewiring and mitochondrial dysfunction, thus identifying an altered H2S metabolism and persulfidation in SOXD. Finally, oxidized glutathione and glutathione trisulfide were able to scavenge sulfite in vitro and in vivo, extending the lifespan of SOXD mice and providing a mechanistic concept of sulfite scavenging for the treatment of this severe metabolic disorder of cysteine catabolism.
Authors
Chun-Yu Fu, Joshua B. Kohl, Filip Liebsch, Davide D’Andrea, Tamás Ditrói, Seiryo Ogata, Franziska Neuser, Max Mai, Anna T. Mellis, Emilia Kouroussis, Masanobu Morita, Titus Gehling, José Angel Santamaria-Araujo, Sin Yuin Yeo, Heike Endepols, Michaela Křížková, Viktor Kozich, Marcus Krueger, Julia B. Hennermann, Uladzimir Barayeu, Takaaki Akaike, Peter Nagy, Milos Filipovic, Guenter Schwarz
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ISSN: 0021-9738 (print), 1558-8238 (online)