Neurogenic heterotopic ossification (NHO) is the formation of ectopic bone generally in muscles surrounding joints following spinal cord or brain injury. We investigated the mechanisms of NHO formation in 64 patients and a mouse model of spinal cord injury–induced NHO. We show that marrow from human NHOs contains hematopoietic stem cell (HSC) niches, in which mesenchymal stromal cells (MSCs) and endothelial cells provide an environment supporting HSC maintenance, proliferation, and differentiation. The transcriptomic signature of MSCs from NHOs shows a neuronal imprinting associated with a molecular network required for HSC support. We demonstrate that oncostatin M (OSM) produced by activated macrophages promotes osteoblastic differentiation and mineralization of human muscle-derived stromal cells surrounding NHOs. The key role of OSM was confirmed using an experimental model of NHO in mice defective for the OSM receptor (OSMR). Our results provide strong evidence that macrophages contribute to NHO formation through the osteogenic action of OSM on muscle cells within an inflammatory context and suggest that OSM/OSMR could be a suitable therapeutic target. Altogether, the evidence of HSCs in ectopic bones growing at the expense of soft tissue in spinal cord/brain-injured patients indicates that inflammation and muscle contribute to HSC regulation by the brain-bone-blood triad.
Frédéric Torossian, Bernadette Guerton, Adrienne Anginot, Kylie A. Alexander, Christophe Desterke, Sabrina Soave, Hsu-Wen Tseng, Nassim Arouche, Laetitia Boutin, Irina Kulina, Marjorie Salga, Beulah Jose, Allison R. Pettit, Denis Clay, Nathalie Rochet, Erica Vlachos, Guillaume Genet, Charlotte Debaud, Philippe Denormandie, François Genet, Natalie A. Sims, Sébastien Banzet, Jean-Pierre Levesque, Jean-Jacques Lataillade, Marie-Caroline Le Bousse-Kerdilès
Sickle cell disease (SCD) results from a point mutation in the β-globin gene forming hemoglobin S (HbS), which polymerizes in deoxygenated erythrocytes, triggering recurrent painful vaso-occlusive crises and chronic hemolytic anemia. Reactivation of fetal Hb (HbF) expression ameliorates these symptoms of SCD. Nuclear factor (erythroid derived-2)–like 2 (Nrf2) is a transcription factor that triggers cytoprotective and antioxidant pathways to limit oxidative damage and inflammation and increases HbF synthesis in CD34+ stem cell–derived erythroid progenitors. We investigated the ability of dimethyl fumarate (DMF), a small-molecule Nrf2 agonist, to activate γ-globin transcription and enhance HbF in tissue culture and in murine and primate models. DMF recruited Nrf2 to the γ-globin promoters and the locus control region of the β-globin locus in erythroleukemia cells, elevated HbF in SCD donor–derived erythroid progenitors, and reduced hypoxia-induced sickling. Chronic DMF administration in SCD mice induced HbF and increased Nrf2-dependent genes to detoxify heme and limit inflammation. This improved hematological parameters, reduced plasma-free Hb, and attenuated inflammatory markers. Chronic DMF administration to nonanemic primates increased γ-globin mRNA in BM and HbF protein in rbc. DMF represents a potential therapy for SCD to induce HbF and augment vasoprotection and heme detoxification.
Sriram Krishnamoorthy, Betty Pace, Dipti Gupta, Sarah Sturtevant, Biaoru Li, Levi Makala, Julia Brittain, Nancy Moore, Benjamin F. Vieira, Timothy Thullen, Ivan Stone, Huo Li, William E. Hobbs, David R. Light
Non–transferrin-bound iron (NTBI) and free hemoglobin (Hb) accumulate in circulation following stored RBC transfusions. This study investigated transfusion, vascular disease, and mortality in guinea pigs after stored RBC transfusion alone and following cotransfusion with apo-transferrin (apo-Tf) and haptoglobin (Hp). The effects of RBC exchange transfusion dose (1, 3, and 9 units), storage period (14 days), and mortality were evaluated in guinea pigs with a vascular disease phenotype. Seven-day mortality and the interaction between iron and Hb as cocontributors to adverse outcome were studied. Concentrations of iron and free Hb were greatest after transfusion with 9 units of stored RBCs compared with fresh RBCs or stored RBCs at 1- and 3-unit volumes. Nine units of stored RBCs led to mortality in vascular diseased animals, but not normal animals. One and 3 units of stored RBCs did not cause a mortality effect, suggesting the concomitant relevance of NTBI and Hb on outcome. Cotransfusion with apo-Tf or Hp restored survival to 100% following 9-unit RBC transfusions in vascular diseased animals. Our data suggest that increases in plasma NTBI and Hb contribute to vascular disease–associated mortality through iron-enhanced Hb oxidation and enhanced tissue injury.
Jin Hyen Baek, Ayla Yalamanoglu, Yamei Gao, Ricardo Guenster, Donat R. Spahn, Dominik J. Schaer, Paul W. Buehler
Myelofibrosis (MF) is a bone marrow disorder characterized by clonal myeloproliferation, aberrant cytokine production, extramedullary hematopoiesis, and bone marrow fibrosis. Although somatic mutations in
Lanzhu Yue, Matthias Bartenstein, Wanke Zhao, Wanting Tina Ho, Ying Han, Cem Murdun, Adam W. Mailloux, Ling Zhang, Xuefeng Wang, Anjali Budhathoki, Kith Pradhan, Franck Rapaport, Huaquan Wang, Zonghong Shao, Xiubao Ren, Ulrich Steidl, Ross L. Levine, Zhizhuang Joe Zhao, Amit Verma, Pearlie K. Epling-Burnette
Diffuse large B cell lymphoma (DLBCL) frequently harbors genetic alterations that activate the B cell receptor (BCR) and TLR pathways, which converge to activate NF-κB. While selective inhibition of BTK with ibrutinib causes clinical responses in relapsed DLBCL patients, most responses are partial and of a short duration. Here, we demonstrated that MyD88 silencing enhanced ibrutinib efficacy in DLBCL cells harboring MyD88 L265P mutations. Chemical downregulation of MyD88 expression with HDAC inhibitors also synergized with ibrutinib. We demonstrate that HDAC inhibitor regulation of MyD88 expression is mediated by STAT3. In turn, STAT3 silencing caused a decrease in MyD88 mRNA and protein levels, and enhanced the ibrutinib antilymphoma effect in MyD88 mutant DLBCL cells. Induced mutations in the STAT3 binding site in the MyD88 promotor region was associated with a decrease in MyD88 transcriptional activity. We also demonstrate that treatment with the HDAC inhibitor panobinostat decreased phosphorylated STAT3 binding to the MyD88 promotor. Accordingly, combined treatment with panobinostat and ibrutinib resulted in enhanced inhibition of NF-κB activity and caused regression of DLBCL xenografts. Our data provide a mechanistic rationale for combining HDAC inhibitors and ibrutinib for the treatment of DLBCL.
Patrizia Mondello, Elliott J. Brea, Elisa De Stanchina, Eneda Toska, Aaron Y. Chang, Myles Fennell, Venkatraman Seshan, Ralph Garippa, David A. Scheinberg, José Baselga, Hans-Guido Wendel, Anas Younes
Jan A. Burger, Kelvin W. Li, Michael J. Keating, Mariela Sivina, Ahmed M. Amer, Naveen Garg, Alessandra Ferrajoli, Xuelin Huang, Hagop Kantarjian, William G. Wierda, Susan O’Brien, Marc K. Hellerstein, Scott M. Turner, Claire L. Emson, Shih-Shih Chen, Xiao-Jie Yan, Dominik Wodarz, Nicholas Chiorazzi
In patients with sickle cell disease (SCD), the polymerization of intraerythrocytic hemoglobin S promotes downstream vaso-occlusive events in the microvasculature. While vaso-occlusion is known to occur in the lung, often in the context of systemic vaso-occlusive crisis and the acute chest syndrome, the pathophysiological mechanisms that incite lung injury are unknown. We used intravital microscopy of the lung in transgenic humanized SCD mice to monitor acute vaso-occlusive events following an acute dose of systemic lipopolysaccharide sufficient to trigger events in SCD but not control mice. We observed cellular microembolism of precapillary pulmonary arteriolar bottlenecks by neutrophil-platelet aggregates. Blood from SCD patients was next studied under flow in an in vitro microfluidic system. Similar to the pulmonary circulation, circulating platelets nucleated around arrested neutrophils, translating to a greater number and duration of neutrophil-platelet interactions compared with normal human blood. Inhibition of platelet P-selectin with function-blocking antibody attenuated the neutrophil-platelet interactions in SCD patient blood in vitro and resolved pulmonary arteriole microembolism in SCD mice in vivo. These results establish the relevance of neutrophil-platelet aggregate formation in lung arterioles in promoting lung vaso-occlusion in SCD and highlight the therapeutic potential of targeting platelet adhesion molecules to prevent acute chest syndrome.
Margaret F. Bennewitz, Maritza A. Jimenez, Ravi Vats, Egemen Tutuncuoglu, Jude Jonassaint, Gregory J. Kato, Mark T. Gladwin, Prithu Sundd
Jack D. Stopa, Donna Neuberg, Maneka Puligandla, Bruce Furie, Robert Flaumenhaft, Jeffrey I. Zwicker
Monique A.J. van Eijndhoven, Josée M. Zijlstra, Nils J. Groenewegen, Esther E.E. Drees, Stuart van Niele, S. Rubina Baglio, Danijela Koppers-Lalic, Hans van der Voorn, Sten F.W.M. Libregts, Marca H.M. Wauben, Renee X. de Menezes, Jan R.T. van Weering, Rienk Nieuwland, Lydia Visser, Anke van den Berg, Daphne de Jong, D. Michiel Pegtel
von Willebrand disease type 2B (VWD-type 2B) is characterized by gain-of-function mutations of von Willebrand factor (vWF) that enhance its binding to platelet glycoprotein Ibα and alter the protein’s multimeric structure. Patients with VWD-type 2B display variable extents of bleeding associated with macrothrombocytopenia and sometimes with thrombopathy. Here, we addressed the molecular mechanism underlying the severe macrothrombocytopenia both in a knockin murine model for VWD-type 2B by introducing the p.V1316M mutation in the murine
Alexandre Kauskot, Sonia Poirault-Chassac, Frédéric Adam, Vincent Muczynski, Gabriel Aymé, Caterina Casari, Jean-Claude Bordet, Christelle Soukaseum, Chantal Rothschild, Valérie Proulle, Audrey Pietrzyk-Nivau, Eliane Berrou, Olivier D. Christophe, Jean-Philippe Rosa, Peter J. Lenting, Marijke Bryckaert, Cécile V. Denis, Dominique Baruch
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