Abstract
Insulin and glucagon are described as having opposing actions on hepatic glycogen metabolism. However, here we showed that their coordinated action promoted glycogen turnover and meal glucose storage. In mice, pharmacological doses of insulin or glucagon failed to alter hepatic glycogen, but the combination produced a robust decrease in glycogen content. Additivity between insulin and glucagon was also seen with the activation of hepatic insulin signaling intermediates. This signaling pathway drove glycogen synthesis, suggesting concurrent actions on glycogen breakdown and repletion. A mixed nutrient meal, which stimulates an increase in both insulin and glucagon, enhanced the incorporation of dietary glucose into hepatic glycogen. This was much more pronounced than the effects of glucose alone, which only stimulated insulin secretion. These findings revealed that glucagon is required for efficient hepatic glucose storage when acting in concert with insulin. Coordinated insulin-glucagon signaling, thus, emerged as a critical mechanism for hepatic glycogen cycling, challenging the classical paradigm that these hormones work in opposition.
Authors
Nidhi Kejriwal, David Bouslov, Cheyenne R. Castle, Riya S. Karve, Galina A. Arkharova, Ashot Sargsyan, Daniel J. Drucker, Guo-Fang Zhang, David A. D’Alessio, Jonathan E. Campbell, Megan E. Capozzi
Abstract
Macrophages, endowed with remarkable phenotypic plasticity, are essential for orchestrating injury responses and regulating iron homeostasis. Given the central role of ferritin heavy chain (FtH) as a molecular rheostat linking iron sequestration to redox-dependent signaling, we examined how myeloid FtH governs renal iron trafficking and ensuing oxidative stress pathways during acute kidney injury (AKI). Transcriptome analysis revealed coupling of FtH deficiency in monocytes and macrophages with activation of ferroptosis, a regulated cell death associated with iron accumulation. Moreover, myeloid FtH deletion worsened AKI, increasing leukocyte infiltration and iron deposition, together with ferroptosis-associated gene induction, oxidative stress, and lipid peroxidation. Notably, α-synuclein (SNCA), an iron-binding protein and the main pathological driver of Parkinson’s disease, was robustly induced both by FtH deficiency and following AKI. Mechanistic studies showed that monomeric SNCA exhibits ferrireductase activity, amplifying redox cycling and promoting ferroptotic cell death. Furthermore, SNCA expression was elevated in kidney pathologies characterized by leukocyte expansion in both mouse models and human cohorts, suggesting that inflammatory microenvironments promote SNCA accumulation and redox imbalance. These findings define a macrophage FtH/SNCA regulatory axis as a key driver of ferroptosis in AKI, implicating SNCA as a pathological nexus between iron dyshomeostasis and inflammatory kidney injury.
Authors
Tanima Chatterjee, Sarah Machado, Kellen Cowen, Mary E. Miller, Bronte Johnson, Yanfeng Zhang, Laura A. Volpicelli-Daley, Lauren A. Fielding, Rudradip Pattanayak, Frida Rosenblum, László Potor, György Balla, Jozsef Balla, Christian Faul, Abolfazl Zarjou
Abstract
Although the pathogenic role of autoantibodies targeting the podocyte protein THSD7A in membranous nephropathy (MN) is well described, the consequences of autoantibody binding for podocyte homeostasis and the function of THSD7A remain unclear. Here, we induced an MN model in control and podocyte-specific Thsd7a-KO (Thsd7a–/–) mice using rabbit anti-THSD7A antibodies, followed by transcriptome and proteome analyses. Anti-THSD7A antibodies in WT mice caused significant loss of key slit diaphragm (SD) proteins, such as nephrin and NEPH1, without transcriptional downregulation. Glomeruli showed substantial transcriptomic and proteomic reconfiguration indicative of extensive podocyte injury, including disruptions in podocyte adhesion, cytoskeletal dynamics, and marked upregulation of ubiquitin-proteasome system components, cathepsins, and ADAM proteases. Notably, experiments in C3-deficient mice revealed that proteolytic activation and SD protein loss are driven by complement-independent pathways. Thsd7a–/– mice only displayed a mild phenotype under basal conditions, and they were completely protected from MN development upon anti-THSD7A antibody transfer. Finally, interactome analysis identified a protein complex, including THSD7A and integrin α3, linking THSD7A complexes to pathogenic regulation of cytoskeleton, adhesion, and membrane signaling in MN. Thus, anti-THSD7A antibodies induce profound molecular reconfiguration, including dysregulated proteolytic systems via a complement-independent pathway, revealing potential therapeutic targets in MN.
Authors
Ming Huang, Moritz Lassé, Silke Dehde, Felicitas E. Hengel, Fatih Demir, Anja M. Billing, Ning Song, Larissa Seifert, Oliver Kretz, Florian Grahammer, Ulf Panzer, Sebastian Brähler, Tobias B. Huber, Gunther Zahner, Markus M. Rinschen, Nicola M. Tomas
Abstract
Adipocytes exist along a functional spectrum: white adipocytes are energy storing, and brown adipocytes have thermogenic capacity such that activation may counteract obesity-related disease. In between are UCP1-expressing beige adipocytes, which can transition between these two energetic states. We previously showed that bone morphogenetic protein 7 (BMP7), a member of the TGF-β superfamily, enables differentiation of brown preadipocytes to mature thermogenic cells. To see whether immortalized, clonal human white and brown preadipocytes (hWAs and hBAs, respectively) would become more thermogenic in response to BMP exposure, we treated them with BMP7 or BMP4 for the first 7 days of a 30-day differentiation protocol. In hBAs, absence of either BMP7 or BMP4 led to lower expression of brown-specific markers and oxygen consumption relative to 7 days with either BMP. hWAs treated for 7 days with either BMP did not increase expression of thermogenic protein UCP1 nor induce a brown-like transcription profile. However, BMP-treated hWAs produced adipocytes that had higher basal and drug-induced maximal oxygen consumption, which was UCP1-independent and due substantially to the futile creatine cycle. Our results demonstrate that energetically quiescent hWAs can be pushed into an energy-expending phenotype without transdifferentiation into beige adipocytes, providing a new approach to treat obesity-related metabolic disease.
Authors
Kelly T. Long, Cheryl Cero, Sahara L. Ali, Nhuquynh Nguyen, Adrienne R. Guarnieri, Ju Hee Kim, Young Jae Bahn, Jurgen Heymann, Jonathan M. Dreyfuss, Sushil G. Rane, Yu-Hua Tseng, Aaron M. Cypess
Abstract
Moderate hyperoxia (30%–60% O2) in premature infants promotes bronchial airway hyperresponsiveness (AHR) via airway smooth muscle (ASM), a key regulator of bronchoconstriction, bronchodilation, and remodeling. Understanding how O2 exposure drives long-term bronchial changes in prematurity is critical for developing therapies for airway disease across the lifespan. Premature lungs have immature antioxidant defenses, potentially due to disrupted mitochondrial dynamics, increasing susceptibility to O2-induced oxidative stress. Thus, mitochondrial homeostasis is highly relevant to ASM dysfunction and airway disease. We propose that hyperoxia in prematurity promotes mitochondrial dysfunction, and that the gasotransmitter hydrogen sulfide (H2S) mitigates O2-induced mitochondrial damage in developing ASM. Human fetal ASM (fASM) cells were exposed to moderate hyperoxia to investigate the effects of exogenous H2S donors (GYY4137, AP39) and stabilization of cystathionine β-synthase (CBS), an H2S biosynthetic enzyme, on mitochondrial structure and function. Hyperoxia impaired fASM cell mitochondrial integrity, while H2S donors in particular, or CBS stabilization attenuated adverse O2 effects on mitochondrial morphology, ROS, respiration, calcium regulation, and contractility. These findings highlight the therapeutic potential of H2S in the premature lung exposed to moderate hyperoxia.
Authors
Colleen M. Bartman, Michael Thompson, Samantha K. Hamrick, Niyati A. Borkar, Daniel Pfeffer-Kleemann, Preetham Ravi, Marta Schiliro, Yak Nak, Christian Vivar Ramon, Li Drake, Y.S. Prakash, Christina Pabelick
Abstract
Heterogeneity in disease severity and treatment response in inflammatory bowel disease (IBD) likely evolves from individual differences in host-microbiota-immune interactions. Histological evaluation of intestinal biopsies is central to diagnosis, but histological parameters that define underlying immune mechanisms are limited. We investigated histological features that distinguish individual patient immune profiles in therapy-naive pediatric IBD patients (age 6–18 years) using biopsy immunohistochemistry and transcriptomics and plasma proteomics across two cohorts. High colonic epithelial expression of secretory leukocyte protease inhibitor (SLPI), a microbiota-induced regulator of epithelial function, occurred in IBD patients with high clinical disease activity and more severe endoscopic and microscopic disease activity. SLPI expression was related to increased neutrophil infiltration, transcriptomic signatures of activation, and genes known to associate with therapeutic resistance. High SLPI colocalized with high densities of IL-17–secreting cells and was associated with high plasma concentrations of Th17-related immune proteins. Additionally, patients with high intestinal SLPI had an intrinsically different immunotype, in which circulating neutrophils exhibited altered transcription of genes involved in neutrophil granule formation, phagocytosis, oxidative phosphorylation, and interferon signaling. Thus, high colonic SLPI expression at diagnosis associates with severe IBD, increased IL-17A–neutrophil pathway responses, and altered transcriptomic wiring of circulating neutrophils.
Authors
Sandrine Nugteren, Beatriz Calado, Ytje Simons-Oosterhuis, Daniëlle H. Hulleman-van Haaften, Willem K. Smits, Renz C.W. Klomberg, Bastiaan Tuk, Mohammed Charrout, Dicky J. Lindenbergh-Kortleve, Michail Doukas, Mathijs A. Sanders, Gregory van Beek, Johanna C. Escher, Lissy de Ridder, Maria Fernanda Pascutti, Janneke N. Samsom
Abstract
GLP-1 receptor (GLP-1R) agonists decrease blood glucose and body weight and reduce rates of cardiovascular and renal disease. Although GLP-1R activation lowers blood pressure (BP), the underlying mechanisms remain incompletely understood and have been attributed to weight loss and endothelial cell GLP-1R signaling. Here, we show that GLP-1Rs in vascular smooth muscle cells (VSMCs) are essential for semaglutide-mediated BP reduction in mice. In contrast, GLP-1Rs in Tie2+ endothelial or immune cells are not required for semaglutide to lower BP. The VSMC GLP-1R is dispensable for the effects of semaglutide on food intake, body weight, and blood glucose but is required for its actions to increase glomerular filtration rate and promote natriuresis. Systemic semaglutide administration resulted in proteomic changes in the renal artery and kidney in pathways related to platelet aggregation, fibrin clot formation, lipid metabolism, and proapoptotic signaling that are abolished in mice lacking VSMC GLP-1R expression. Moreover, semaglutide directly induced vasorelaxation in preconstricted mesenteric arteries ex vivo. Together, these findings identify VSMCs as a key cellular target linking GLP-1R activation to BP regulation, renal electrolyte excretion, and proteomic changes in renal artery and kidney.
Authors
Kyle D. Medak, Jacqueline A. Koehler, Laurie L. Baggio, Maria J. Gonzalez-Rellan, Chi Kin Wong, Xiemin Cao, Vivikta Rao, Sean Kao, Yu Cui, Jiayi Fu, Easton Liaw, M. Golam Kabir, Jie Zhang, Jin Wei, Daniel J. Drucker
Abstract
Immune checkpoint inhibitors (ICIs) can cause immune-related adverse events (irAEs), with acute interstitial nephritis (ICI-AIN) being the most common irAE. While the exact mechanism remains unclear, upregulation of IFN-γ and TNF-α pathways has been implicated. This study used a humanized chimeric PD-1/PD-L1 mouse model to assess renal effects of ICIs, alone or combined with proinflammatory cytokines, and to test if selective TNF-α blockade could prevent ICI-AIN. Mice were randomly divided into 4 experimental groups: Control, ICI-Only, ICI-Cytokines (ICI-Cyt), and ICI-Block (ICI-TNF-α blockade). Renal function and cytokine profiles were assessed, while kidney tissue was analyzed using microscopy and single-cell RNA-seq. Histology revealed increased renal infiltration of CD4+/CD8+ T cells in ICI-treated groups and decreased TNF-α expression following TNF-α blockade. Additionally, kidney tissue ELISA demonstrated reduced IFN-γ levels following TNF-α blockade. Plasma IL-6, MCP-1, and TNF-α were lower in ICI-Block mice. Single-cell RNA-seq revealed shifts in immune cell populations and genes of interest including Bcl2a1, Icos, Il18r1, Ccr2, and Jaml. This humanized model replicates ICI-AIN key features, revealing a synergistic role of ICIs and proinflammatory cytokines. TNF-α blockade demonstrated protective effects, supporting its potential role in mitigating the risk of ICI-AIN.
Authors
Victor D. Cuenca Narvaez, Coraima Nava Chavez, Omar Al Refai, Johanna E.J. Jacobs, Luis E. Gutierrez, Song Zhang, Xiaoyan Li, Jacob B. Hirdler, Michael F. Romero, Joerg Herrmann, Xiaogang Li, Haidong Dong, Alfonso Eirin, Sandra M. Herrmann
Abstract
Viral lower respiratory tract infections are common early in life and are associated with long-term development of asthma, a chronic condition defined by reversible airflow obstruction secondary to inflammation. Understanding the immunological mechanism connecting these two pathologies observed early in life becomes imperative to guide therapeutic measures. To investigate this connection, neonatal (days 4–6) or adult mice were infected with human metapneumovirus (HMPV) followed by a secondary HMPV infection 6 weeks later. Mice initially infected as neonates demonstrated increased mucus production, eosinophil recruitment, airway hyperresponsiveness, and Th2 T cell differentiation after rechallenge compared with adult mice rechallenged with HMPV. Neonatal HMPV infection led to formation of Th2 clonally expanded tissue-resident memory (TRM) T cells that were absent after adult HMPV. FTY720-mediated disruption of lymphocyte circulation demonstrated that TRMs contributed to pathology. Local depletion of lung CD4+ T cells and JAK2 inhibition mitigated pathology. These findings suggest TRMs uniquely generated after early-life viral infection can contribute to Th2-driven asthma pathology.
Authors
Emma E. Brown, Jie Lan, Olivia B. Parks, Li Fan, Dequan Lou, Alysia McCray, Lisa Mathews, Alexander J. Wardropper, Anna Shull, Michelle L. Manni, Heth R. Turnquist, Kong Chen, Taylor Eddens
Abstract
Mitochondrial dysfunction devastates the heart in major cardiovascular diseases, yet the mechanisms governing mitochondrial quality control remain elusive. We discovered that TIGAR (TP53-induced glycolysis and apoptosis regulator) deficiency established profound cardiac protection through developmental epigenetic programming of Parkin expression. Using mice with whole-body and cardiomyocyte-specific TIGAR knockout, we demonstrated remarkable cardioprotection following myocardial infarction with maintained ejection fraction, and complete resistance to diet-induced cardiac hypertrophy despite comparable weight gain. TIGAR deficiency triggered dramatic increases in Parkin expression across all somatic tissues except testes, where Parkin levels remained extraordinarily high (100-fold greater than cardiac levels) regardless of TIGAR status, revealing tissue-specific regulatory mechanisms. This protection was entirely Parkin dependent, as double-knockout mice lost all cardioprotective benefits. Crucially, adult TIGAR manipulation failed to alter Parkin levels, demonstrating that this pathway operated exclusively during critical developmental windows to program lifelong cardiac resilience. Whole-genome bisulfite sequencing identified reduced DNA methylation in Prkn intron 10 as the key regulatory mechanism, with CRISPR deletion dramatically increasing Parkin expression in multiple cell lines. Our findings reveal how early cardiac metabolism programs lifelong cardiac function through epigenetic mechanisms, and identify developmental metabolic programming as a potential therapeutic target for preventing both ischemic heart disease and metabolic cardiomyopathy.
Authors
Yan Tang, Stanislovas S. Jankauskas, Li Liu, Xujun Wang, Alus M. Xiaoli, Fajun Yang, Gaetano Santulli, Daorong Feng, Jeffrey E. Pessin
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