Loss of Sbds in zebrafish leads to neutropenia and pancreas and liver atrophy

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Abstract

Shwachman-Diamond syndrome (SDS) is characterized by exocrine pancreatic insufficiency, neutropenia, and skeletal abnormalities. Biallelic mutations in SBDS, which encodes a ribosome maturation factor, are found in 90% of SDS cases. Sbds-/- mice are embryonic lethal. Using CRISPR/Cas9 editing, we created sbds-deficient zebrafish strains. Sbds protein levels progressively decreased and became undetectable at 10 days post fertilization (dpf). Polysome analysis revealed decreased 80S ribosomes. Homozygous mutant fish developed normally until 15 dpf. Mutant fish subsequently have stunted growth and shows signs of atrophy in pancreas, liver, and intestine. In addition, neutropenia occurred by 5 dpf. Upregulation of tp53 mRNA did not occur until 10 dpf and inhibition of proliferation correlating with death by 21 dpf. Transcriptome analysis showed tp53 activation through upregulation of genes involved in cell cycle arrest, cdkn1a and ccng1, and apoptosis, puma and mdm2. However, elimination of Tp53 function did not prevent lethality. Because of growth retardation and atrophy of intestinal epithelia, we studied the effects of starvation on wildtype fish. Starved wildtype fish showed intestinal atrophy, zymogen granule loss, and tp53 upregulation – similar to the mutant phenotype. In addition, there was reduction in neutral lipid storage and ribosomal protein amount, similar to the mutant phenotype. Thus, loss of Sbds in zebrafish phenocopies much of the human disease and is associated with growth arrest and tissue atrophy, particularly of the gastrointestinal system, at the larval stage. A variety of stress responses, some associated with Tp53, contribute to pathophysiology of SDS.

Authors

Usua Oyarbide, Arish N. Shah, Wilmer Amaya-Mejia, Matthew Snyderman, Margaret Kell, Daniela Allende, Eliezer Calo, Jacek Topczewski, Seth Corey

Regulation of glycolysis and the Warburg effect in wound healing

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Abstract

One of the most significant adverse post-burn responses is abnormal scar formation, such as keloids. Despite its prolificacy, the underlying pathophysiology of keloid development is unknown. We recently demonstrated that NLRP3 inflammasome, the master regulator of inflammatory and metabolic responses (e.g. aerobic glycolysis), is essential for physiological wound healing. Therefore, burn patients who develop keloids may exhibit altered immunometabolic responses at the site of injury, which interferes with normal healing and portends keloid development. Here, we confirmed keloid NLRP3 activation (caspase-1 (p<0.05), IL1β (p<0.05), IL18 (p<0.01)) and upregulation in Glut1 (p<0.001) and glycolytic enzymes. Burn skin similarly displayed enhanced glycolysis and Glut1 expression (p<0.01). However, Glut1 was significantly higher in keloid compared to non-keloid burn patients (>2 standard deviations above mean). Targeting aberrant glucose metabolism with shikonin, a pyruvate kinase M2 inhibitor, dampened NLRP3-mediated inflammation (caspase-1 (p<0.05), IL1β (p<0.01)) and improved healing in vivo. In summary, burn skin exhibited evidence of Warburg-like metabolism, similar to keloids. Targeting this altered metabolism could change the trajectory towards normal scarring, indicating the clinical possibility of shikonin for abnormal scar prevention.

Authors

Roohi Vinaik, Dalia Barayan, Christopher Auger, Abdikarim Abdullahi, Marc G. Jeschke

AAV9 gene transfer of cMyBPC N-terminal domains ameliorates cardiomyopathy in cMyBPC deficient mice

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Abstract

Decreased cardiac myosin-binding protein C (cMyBPC) expression due to inheritable mutations is thought to contribute to the hypertrophic cardiomyopathy (HCM) phenotype, suggesting increasing cMyBPC content is of therapeutic benefit. In vitro assays show cMyBPC N-terminal domains (NTDs) contain structural elements necessary and sufficient to modulate acto-myosin interactions, but it is unknown if they can regulate in vivo myocardial function. To test if NTDs can recapitulate the effects of full-length (FL) cMyBPC in rescuing cardiac function in a cMyBPC-null mouse model of HCM, we assessed the efficacy of AAV9 gene transfer of a cMyBPC NTD containing domains C0C2 and compared its therapeutic potential with AAV9-FL gene replacement. AAV9 vectors were administered systemically at neonatal day 1, when early-onset disease phenotypes begin to manifest. A comprehensive analysis of in vivo and in vitro function was performed following cMyBPC gene transfer. Our results show that a systemic injection of AAV9-C0C2 gene transfer significantly improved cardiac function (e.g. 52.24±1.69 ejection fraction in C0C2 treated group compared to 40.07±1.97 in control cMyBPC-/- group, p<0.05) and reduced the histopathologic signs of cardiomyopathy. Furthermore, C0C2 significantly slowed and normalized the accelerated cross-bridge kinetics (32.41% decrease of krel) found in cMyBPC-/- control myocardium. Results indicate that C0C2 can rescue biomechanical defects of cMyBPC deficiency and the NTD may be a target region for therapeutic myofilament kinetic manipulation.

Authors

Jiayang Li, Ranganath Mamidi, Chang Yoon Doh, Joshua B. Holmes, Nikhil Bharambe, Rajesh Ramachandran, Julian E. Stelzer

Resolvin D1 supports skeletal myofiber regeneration via actions on myeloid and muscle stem cells

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Abstract

Specialized pro-resolving mediators (SPMs) actively limit inflammation and expedite its resolution by modulating leukocyte recruitment and function. Here we profiled intramuscular lipid mediators via LC-MS based metabolipidomics following myofiber injury and investigated the potential role of SPMs in skeletal muscle inflammation and repair. Both pro-inflammatory eicosanoids and SPMs increased following myofiber damage induced by either intramuscular injection of barium chloride or synergist ablation-induced functional muscle overload. Daily systemic administration of the SPM resolvin D1 (RvD1) as an immunoresolvent limited the degree and duration of inflammation, enhanced regenerating myofiber growth, and improved recovery of muscle strength. RvD1 suppressed inflammatory cytokine expression, enhanced polymorphonuclear cell clearance, modulated the local muscle stem cell response, and polarized intramuscular macrophages to a more pro-regenerative subset. RvD1 had minimal direct impact on in-vitro myogenesis but directly suppressed myokine production and stimulated macrophage phagocytosis, showing that SPMs can modulate both infiltrating myeloid and resident muscle cell populations. These data reveal the efficacy of immunoresolvents as a novel alternative to classical anti-inflammatory interventions in the management of muscle injuries to modulate inflammation while stimulating tissue repair.

Authors

James F. Markworth, Lemuel A. Brown, Eunice Lim, Carolyn Floyd, Jacqueline Larouche, Jesus A. Castor-Macias, Kristoffer B. Sugg, Dylan C. Sarver, Peter C. D. Macpherson, Carol S. Davis, Carlos A. Aguilar, Krishna Rao Maddipati, Susan V. Brooks

Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonist

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Abstract

Tirzepatide (LY3298176) is a dual GIP and GLP-1 receptor agonist under development for the treatment of type 2 diabetes mellitus (T2DM), obesity, and non-alcoholic steatohepatitis. Early phase trials in T2DM indicate that tirzepatide improves clinical outcomes beyond those achieved by a selective GLP-1 receptor agonist. Therefore, we hypothesized that the integrated potency and signaling properties of tirzepatide provide a unique pharmacological profile tailored for improving broad metabolic control. Here, we establish methodology for calculating occupancy of each receptor for clinically efficacious doses of the drug. This analysis reveals a greater degree of engagement of tirzepatide for the GIP receptor (GIPR) than the GLP-1 receptor (GLP-1R), corroborating an imbalanced mechanism of action. Pharmacologically, signaling studies demonstrate that tirzepatide mimics the actions of native GIP at the GIPR but show bias at the GLP-1R to favor cAMP generation over β-arrestin recruitment, coincident with a weaker ability to drive GLP-1R internalization compared with GLP-1. Experiments in primary islets reveal β-arrestin1 limits the insulin response to GLP-1, but not GIP or tirzepatide, suggesting the biased agonism of tirzepatide enhances insulin secretion. Imbalance toward GIPR, combined with distinct signaling properties at the GLP-1R, together may account for the promising efficacy of this new investigational agent.

Authors

Francis S. Willard, Jonathan D. Douros, Maria B. N. Gabe, Aaron D. Showalter, David B. Wainscott, Todd M. Suter, Megan E. Capozzi, Wijnand J. C. van der Velden, Cynthia. Stutsman, Guemalli R. Cardona, Shweta Urva, Paul J. Emmerson, Jens J. Holst, David A. D'Alessio, Matthew P. Coghlan, Mette M. Rosenkilde, Jonathan E. Campbell, Kyle W. Sloop

ANGPTL8 has both endocrine and autocrine effects on substrate utilization

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Abstract

The angiopoietin-like protein ANGPTL8 (A8) is one of three ANGPTLs (A8, A3, A4) that coordinate changes in triglyceride (TG) delivery to tissues by inhibiting lipoprotein lipase (LPL), an enzyme that hydrolyzes TG. Previously we showed that A8, which is expressed in liver and adipose tissue, is required to redirect dietary TG from oxidative to storage tissues following food intake. Here we show that A8 from liver and adipose tissue have different roles in this process. Mice lacking hepatic A8 have no circulating A8, high intravascular LPL activity, low plasma TG levels, and evidence of decreased delivery of dietary lipids to adipose tissue. In contrast, mice lacking A8 in adipose tissue have higher postprandial TG levels and no alteration in fatty acid composition in adipocytes. Expression of A8, together with A4, in cultured cells reduced A4 secretion and A4-mediated LPL inhibition. Thus, hepatic A8 (with A3) acts in an endocrine fashion to inhibit intravascular LPL in oxidative tissues, whereas A8 in adipose tissue enhances LPL activity by autocrine/paracrine inhibition of A4. These combined actions of A8 ensure that TG stores are rapidly replenished and sufficient energy is available until the next meal.

Authors

Federico Oldoni, Haili Cheng, Serena Banfi, Viktoria Gusarova, Jonathan C. Cohen, Helen H. Hobbs

Wiskott-Aldrich syndrome protein restricts cGAS-STING activation by dsDNA immune complexes

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Abstract

Dysregulated sensing of self nucleic acid is a leading cause of autoimmunity in multifactorial and monogenic diseases. Mutations in Wiskott-Aldrich syndrome protein (WASp), a key regulator of cytoskeletal dynamics in immune cells, cause autoimmune manifestations and increased production of type-I interferons by innate cells. Here we show that complexes of self-DNA and autoantibodies (DNA-IC) contribute to elevated interferon levels via activation of the cGAS-STING pathway of cytosolic sensing. Mechanistically, lack of endosomal F-actin nucleation by WASp causes a delay in endolysosomal maturation and prolongs the transit time of ingested DNA-IC. Stalling in maturation-defective organelles facilitates leakage of DNA-IC into the cytosol, promoting activation of the TBK1-STING pathway. Genetic deletion of STING, STING and cGAS chemical inhibitors abolish interferon production and rescue systemic activation of interferon stimulated genes in vivo. These data unveil the contribution of cytosolic self-nucleic acid sensing in WAS and underscore the importance of WASp-mediated endosomal actin remodelling to prevent innate activation.

Authors

Giulia Maria Piperno, Asma Naseem, Giulia Silvestrelli, Roberto Amadio, Nicoletta Caronni, Karla Evelia Cervantes Luevano, Nalan Liv, Judith Klumperman, Andrea Colliva, Hashim Ali, Francesca Graziano, Philippe Benaroch, Hans Haecker, Richard N. Hanna, Federica Benvenuti

Regulator combinations identify systemic sclerosis patients with more severe disease

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Abstract

Systemic sclerosis (SSc) is a heterogeneous autoimmune disorder that results in skin fibrosis, autoantibody production and internal organ dysfunction. We previously identified four ‘intrinsic’ subsets of SSc based upon skin gene expression that are found across organ systems. Gene expression regulators that underlie the SSc intrinsic subsets, or are associated with clinical covariates, have not been systematically characterized. Here we present a computational framework to calculate the activity scores of gene expression regulators and identify their associations with SSc clinical outcomes. We find regulator activity scores can reproduce the intrinsic molecular subsets with distinct sets of regulators identified for inflammatory, fibroproliferative and normal-like samples. Regulators most highly correlated with modified Rodnan skin score (MRSS) also varied by intrinsic subset. We identify a subgroup of fibroproliferative/inflammatory SSc patients with more severe pathophenotypes. We further identify a subgroup of SSc patients that had higher MRSS and increased likelihood of interstitial lung disease. Using an independent cohort, we show this group was most likely to show forced vital capacity decline over a period of 36 – 54 months. Our results demonstrate an association between the activation of regulators, gene expression subsets and clinical variables that can identify SSc patients with more severe disease.

Authors

Yue Wang, Jennifer M. Franks, Monica Yang, Diana M. Toledo, Tammara A. Wood, Monique Hinchcliff, Michael L. Whitfield

Glioma patient profiling reveals the dominant immune suppressive adenosine axis is refractory to immune function restoration

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Abstract

Purpose: There is a rapidly evolving portfolio of immune therapeutic modulators, but the relative incidence of immune targets in human gliomas is unknown. In order to prioritize available immune therapeutics, immune profiling across glioma grades was conducted followed by preclinical determinations of therapeutic effect in immune competent mice harboring gliomas. Methods: CD4+ and CD8+ T cells and CD11b+ myeloid cells were isolated from the blood of healthy donors and the blood and tumors of newly diagnosed and recurrent glioma patients and profiled for the expression of immune modulatory targets with an available therapeutic. Preclinical murine models of glioma were used to assess therapeutic efficacy of agents targeting the most frequently expressed immune targets. Immune effector function was analyzed in the setting of glioma induced immune suppression. Results: In glioma patients, the adenosine-CD73-CD39 immune suppressive pathway was most frequently expressed, followed by PD-1. CD73 expression was upregulated on immune cells by 2-hydroxygluterate in IDH1 mutant glioma patients. In multiple murine glioma models, including those that express CD73, adenosine receptor inhibitors demonstrated a modest therapeutic response; however, the addition of other inhibitors of the adenosine pathway did not further enhance this therapeutic effect. Although adenosine receptor inhibitors could recover immunological effector functions in T cells after the engagement of this pathway, immune recovery was impaired in the presence of gliomas, indicating that irreversible immune exhaustion limits the effectiveness of inhibitors of the adenosine pathway in glioma patients. Conclusions: This study illustrates vetting steps that should be considered prior to clinical trial implementation for immunotherapy resistant cancers including testing an agents ability to restore immunological function in the context of intended use.

Authors

Martina Ott, Karl-Heinz Tomaszowski, Anantha Marisetty, Ling-Yuan Kong, Jun Wei, Maya Duna, Katia Blumberg, Xiaorong Ji, Carmen B Jacobs, Gregory N. Fuller, Lauren A. Langford, Jason T. Huse, James P. Long, Jian Hu, Shulin Li, Jeffrey S. Weinberg, Sujit Prabhu, Raymond Sawaya, Sherise D. Ferguson, Ganesh Rao, Frederick F. Lang, Michael A. Curran, Amy B. Heimberger

Tubular HIPK2 is a key contributor to renal fibrosis

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Abstract

Using the global Hipk2-null mice in various models of kidney disease, we previously demonstrated the central role of homeodomain interacting protein kinase 2 (HIPK2) in the development of renal fibrosis. However, whether the renal tubular epithelial cell (RTEC)-specific HIPK2 function significantly contributed to renal fibrogenesis had not been established. Herein, using RTEC-specific HIPK2 null mice and transgenic mice with RTEC-specific overexpression of the wildtype (WT) or kinase-dead (KD) mutant of HIPK2, we now show that the modulation of tubular HIPK2 expression and activity can profoundly affect renal fibrosis development in vivo. The loss of HIPK2 expression in RTECs resulted in a marked diminution of renal fibrosis in mouse models of unilateral obstruction (UUO) and HIV-associated nephropathy (HIVAN) in Tg26 mice, which was associated with the reduction of Smad3 activation and downstream expression of profibrotic markers. Conversely, the overexpression of WT HIPK2 in RTECs accentuated the extent of renal fibrosis in the setting of UUO, HIVAN, and folic acid nephropathy (FAN) in mice. Importantly, the overexpression of HIPK2 KD mutant or administration of BT173, an allosteric inhibitor of HIPK2-Smad3 interaction, markedly attenuated the renal fibrosis in these mouse models of kidney disease, indicating that HIPK2 requires both the kinase activity and its interaction with Smad3 to promote TGF--mediated renal fibrosis. Together, these results establish an important RTEC-specific role of HIPK2 in kidney fibrosis and further substantiates the inhibition of HIPK2 as a therapeutic approach toward renal fibrosis.

Authors

Wenzhen Xiao, Jing E, Li Bao, Ying Fan, Yuanmeng Jin, Andrew Wang, David Bauman, Zhengzhe Li, Ya-Li Zheng, Ruijie Liu, Kyung Lee, John Cijiang He