Plasma cell-free DNA (cfDNA), a marker of disease severity in sepsis, is a recognized driver of thromboinflammation and a potential therapeutic target. In sepsis, plasma cfDNA is mostly derived from neutrophil extracellular trap (NET) degradation. Proposed NET-directed therapeutic strategies include preventing NET formation or accelerating NET degradation. However, NET digestion liberates pathogens and releases cfDNA that promote thrombosis and endothelial cell injury. We propose an alternative strategy of cfDNA and NET stabilization with chemokine platelet factor 4 (PF4, CXCL4). We previously showed that human PF4 (hPF4) enhances NET-mediated microbial entrapment. We now show that hPF4 interferes with thrombogenicity of cfDNA and NETs by preventing their cleavage to short-fragment and single-stranded cfDNA that more effectively activates the contact pathway of coagulation. In vitro, hPF4 also inhibits cfDNA-induced endothelial tissue factor surface expression and von Willebrand factor release. In vivo, hPF4 expression reduced plasma thrombin-antithrombin (TAT) levels in animals infused with exogenous cfDNA. Following lipopolysaccharide challenge, Cxcl4–/– mice had significant elevation in plasma TAT, cfDNA, and cystatin C levels, effects prevented by hPF4 infusion. These results show that hPF4 interacts with cfDNA and NETs to limit thrombosis and endothelial injury, an observation of potential clinical benefit in the treatment of sepsis.
Anh T.P. Ngo, Abigail Skidmore, Jenna Oberg, Irene Yarovoi, Amrita Sarkar, Nate Levine, Veronica Bochenek, Guohua Zhao, Lubica Rauova, M. Anna Kowalska, Kaitlyn Eckart, Nilam S. Mangalmurti, Ann Rux, Douglas B. Cines, Mortimer Poncz, Kandace Gollomp
Patients with Down syndrome (DS, trisomy 21, T21) are at increased risk of transient abnormal myelopoiesis (TAM) and acute megakaryoblastic leukemia (ML-DS). Both TAM and ML-DS require prenatal somatic mutations in GATA1, resulting in the truncated isoform GATA1s. The mechanism by which individual chromosome 21 (HSA21) genes synergize with GATA1s for leukemic transformation is challenging to study, in part due to limited human cell models with wild type GATA1 or GATA1s. HSA21-encoded DYRK1A is overexpressed in ML-DS and may be a therapeutic target. To determine how DYRK1A influences hematopoiesis in concert with GATA1s, we used gene editing to disrupt all 3 alleles of DYRK1A in isogenic T21 induced pluripotent stem cells (iPSCs) with and without the GATA1s mutation. Unexpectedly, hematopoietic differentiation revealed that DYRK1A loss combined with GATA1s leads to increased megakaryocyte proliferation and decreased maturation. This proliferative phenotype was associated with upregulation of D-type cyclins and hyperphosphorylation of Rb to allow E2F release and de-repression of its downstream targets. Notably, DYRK1A loss had no effect in T21/wtGATA1 megakaryocytes. These surprising results suggest that DYRK1A and GATA1 may synergistically restrain megakaryocyte proliferation in Trisomy 21 and that DYRK1A inhibition may not be a therapeutic option for GATA1s-associated leukemias.
Ying Ting Sit, Kaoru Takasaki, Hyun Hyung An, Yan Xiao, Christian Hurtz, Peter Gearhart, Zhe Zhang, Paul Gadue, Deborah French, Stella T. Chou
Hereditary spherocytosis (HS) is the most common non-immune hereditary chronic hemolytic anemia after hemoglobinopathies. The genetic defects in membrane function causing HS leads to perturbation of red cell metabolome, with altered glycolysis. In mice genetically lacking protein 4.2 (4.2-/-, Epb42), a murine model of HS, we show increased expression of pyruvate kinase (Pk) isoforms in whole and fractioned red cells in conjunction with abnormalities in the glycolytic pathway and in GSH system. Mitapivat, a PKs activator, metabolically re-programs 4.2-/- mouse red cells with amelioration of glycolysis and GSH cycle. This results in improved osmotic fragility, reduced phosphatidyl-serine (PS) positivity and decrease in erythroid vesicles release in vitro. Mitapivat treatment significantly decreases erythrophagocytosis and beneficially impacts iron homeostasis. In mild/moderate HS, the beneficial effect of splenectomy is still controversial. Here, we show that splenectomy improves anemia in 4.2-/- mice and that mitapivat is non-inferior to splenectomy. An additional benefit of mitapivat treatment is lower expression of markers of inflammatory vasculopathy in 4.2-/- mice with or without splenectomy, indicating a multi-systemic action of mitapivat. These findings support the notion that mitapivat treatment should be considered for symptomatic HS.
Alessandro Matte, Anand Babu Wilson, Federica Gevi, Enrica Federti, Antonio Recchiuti, Giulia Ferri, Anna Maria Brunati, Mario Angelo Pagano, Roberta Russo, Christophe Leboeuf, Anne Janin, Anna Maria Timperio, Achille Iolascon, Elisa Gremese, Lenny Dang, Narla Mohandas, Carlo Brugnara, Lucia De Franceschi
Overexpression of Phosphatases of Regenerating Liver 2 (PRL2), detected in numerous diverse cancers, is often associated with increased severity and poor patient prognosis. PRL2-catalyzed tyrosine dephosphorylation of the tumor suppressor PTEN results in increased PTEN degradation, and has been identified as a mechanism underlying PRL2 oncogenic activity. Overexpression of PRL2, coincident with reduced PTEN protein, is frequently observed in Acute Myeloid Leukemia (AML) patients. In the current study, a PTEN-knockdown AML animal model was generated to assess the impact of conditional PRL2 inhibition on the level of PTEN protein and the development and progression of AML. Inhibition of PRL2 resulted in a significant increase in median animal survival, from 40 weeks to greater than 60 weeks. The prolonged survival reflected delayed expansion of aberrantly differentiated hematopoietic stem cells into leukemia blasts, resulting in extended time required for clinically relevant leukemia blast accumulation in the bone marrow niche. Leukemia blast suppression following PRL2 inhibition was correlated with an increase in PTEN, and downregulation of AKT/mTOR regulated pathways. These observations directly established, in a disease model, the viability of PRL2 inhibition as a therapeutic strategy for improving clinical outcomes in AML and potentially other PTEN-deficient cancers by slowing cancer progression.
Colin Carlock, Yunpeng Bai, Allison Paige-Hood, Qinglin Li, Frederick Nguele Meke, Zhong-Yin Zhang
Thrombosis is a common complication of advanced cancer. Yet the cellular mechanisms linking malignancy to thrombosis are poorly understood. The unfolded protein response (UPR) is an ER stress response associated with advanced cancers. A proteomic evaluation of plasmas from gastric and non-small cell lung cancer patients who were monitored prospectively for venous thromboembolism demonstrated increased levels of UPR-related markers in plasmas of patients who developed clots compared to those who did not. Release of procoagulant activity into supernatants of gastric, lung, and pancreatic cancer cells was enhanced by UPR induction and blocked by antagonists of the UPR receptors IRE1α or PERK. Release of extracellular vesicles bearing tissue factor (EVTF) from pancreatic cancer cells was inhibited by siRNA-mediated knockdown of IRE1α/XBP1 or PERK pathways. Induction of UPR did not increase TF synthesis, but rather stimulated localization of TF to the cell surface. UPR-induced TF delivery to EVTFs was inhibited by Arf1 knockdown or GBF1 antagonism, confirming the role of vesicular trafficking. Our findings show that UPR activation results in increased vesicular trafficking leading to release of prothrombotic EVTFs, thus providing a mechanistic link between ER stress and cancer-associated thrombosis.
Oluwatoyosi Muse, Rushad Patell, Christian G. Peters, Moua Yang, Emale El-Darzi, Sol Schulman, Anna Falanga, Marina Marchetti, Laura Russo, Jeffrey I. Zwicker, Robert Flaumenhaft
Posttransplant cyclophosphamide (PTCy) is associated with a low incidence of chronic graft-versus-host disease (cGVHD) following hematopoietic stem cell (HSC) transplantation. Previous studies have shown the important roles of B cell immunity in cGVHD development. Here, we investigated the long-term reconstitution of B lymphopoiesis after PTCy using murine models. We first demonstrated that the immune homeostatic abnormality leading to cGVHD is characterized by an initial increase in effector T cells in the bone marrow and subsequent B and Treg cytopenia. PTCy, but not cyclosporine A or rapamycin, inhibits the initial alloreactive T cell response, which restores intra-bone marrow B lymphogenesis with a concomitant vigorous increase in Tregs. This leads to profound changes in posttransplant B cell homeostasis, including decreased B cell activating factors, increased transitional and regulatory B cells, and decreased germinal center B cells. To identify the cells responsible for PTCy-induced B cell tolerance, we selectively depleted Treg populations that were graft or HSC derived using DEREG mice. Deletion of either Treg population without PTCy resulted in critical B cytopenia. PTCy rescued B lymphopoiesis from graft-derived Treg deletion. In contrast, the negative effect of HSC-derived Treg deletion could not be overcome by PTCy, indicating that HSC-derived Tregs are essential for maintaining favorable B lymphopoiesis following PTCy. These findings define the mechanisms by which PTCy restores homeostasis of the B cell lineage and reestablishes immune tolerance.
Yuichi Sumii, Takumi Kondo, Shuntaro Ikegawa, Takuya Fukumi, Miki Iwamoto, Midori Filiz Nishimura, Hiroyuki Sugiura, Yasuhisa Sando, Makoto Nakamura, Yusuke Meguri, Takashi Matsushita, Naoki Tanimine, Maiko Kimura, Noboru Asada, Daisuke Ennishi, Yoshinobu Maeda, Ken-ichi Matsuoka
Loss of function mutations in the DNA methyltransferase 3A (DNMT3A) are seen in a large number of AML patients with normal cytogenetics and are frequently associated with poor prognosis. DNMT3A mutations are an early pre-leukemic event, which when combined with other genetic lesions result in full blown leukemia. Here, we show that loss of Dnmt3a in HSC/Ps results in myeloproliferation, which is associated with hyperactivation of the PI3Kinase pathway. PI3Kα/β or the PI3Kα/δ inhibitor treatment partially corrects myeloproliferation, although the partial rescue is more efficient in response to the PI3Kα/β inhibitor treatment. In vivo RNA-seq analysis on drug treated Dnmt3a–/– HSC/Ps showed a reduction in the expression of genes associated with chemokines, inflammation, cell attachment and extracellular matrix compared to controls. Remarkably, drug treated leukemic mice showed a reversal in the enhanced fetal liver HSC like gene signature observed in vehicle treated Dnmt3a–/– LSK cells as well as a reduction in the expression of genes involved in regulating actin cytoskeleton-based functions including the RHO/RAC GTPases. In a human PDX model bearing DNMT3A mutant AML, PI3Kα/β inhibitor treatment prolonged their survival and rescued the leukemic burden. Our results identify a new target for treating DNMT3A mutation driven myeloid malignancies.
Lakshmi Reddy Palam, Baskar Ramdas, Katelyn M. Pickerell, Santhosh Kumar Pasupuleti, Rahul Kanumuri, Annamaria Cesarano, Megan Szymanski, Bryce M. Selman, Utpal P. Davé, George Sandusky, Fabiana Perna, Sophie Paczesny, Reuben Kapur
To better characterize the heterogeneity of multiple myeloma (MM), we profiled plasma cells (PCs) and their B cell lymphopoiesis in the BM samples from patients with monoclonal gammopathy of undetermined significance, smoldering MM, and active MM by mass cytometry (CyTOF) analysis. Characterization of intra- and interneoplastic heterogeneity of malignant plasmablasts and PCs revealed overexpression of the MM SET domain (MMSET), Notch-1, and CD47. Variations in upregulation of B cell signaling regulators (IFN regulatory factor 4 [IRF-4], CXCR4, B cell lymphoma 6 [Bcl-6], c-Myc, myeloid differentiation primary response protein 88 [MYD88], and spliced X box-binding protein 1 [sXBP-1]) and aberrant markers (CD319, CD269, CD200, CD117, CD56, and CD28) were associated with different clinical outcomes in clonal PC subsets. In addition, prognosis was related to heterogeneity in subclonal expression of stemness markers, including neuroepithelial stem cell protein (Nestin), SRY-box transcription factor 2 (Sox2), Krüppel-like factor 4 (KLF-4), and Nanog. Furthermore, we have defined significantly elevated levels of MMSET, MYD88, c-Myc, CD243, Notch-1, and CD47 from hematopoietic stem cells to PCs in myeloma B cell lymphopoiesis, noted even in premalignant conditions, with variably modulated expression of B cell development regulators, including IRF-4, Bcl-2, Bcl-6, and sXBP-1; aberrant PC markers (such as CD52, CD44, CD200, CD81, CD269, CD117, and CXCR4); and stemness-controlling regulators, including Nanog, KLF-4, octamer-binding transcription factor 3/4 (Oct3/4), Sox2, and retinoic acid receptor α2 (RARα2). This study provides the rationale for precise molecular profiling of patients with MM by CyTOF technology to define disease heterogeneity and prognosis.
Jana Jakubikova, Danka Cholujova, Gabor Beke, Teru Hideshima, Lubos Klucar, Merav Leiba, Krzysztof Jamroziak, Paul G. Richardson, Efstathios Kastritis, David M. Dorfman, Kenneth C. Anderson
Reactivation of human cytomegalovirus (HCMV) from latency is a frequent complication following hematopoietic stem cell transplantation (HSCT). The development of acute graft-versus-host disease (GVHD) is a significant risk factor for HCMV disease. Using a murine GVHD model in animals latently infected with murine CMV (MCMV) we studied preventive and therapeutic interventions in this high-risk scenario of HSCT. Mice latently infected with MCMV reactivated MCMV and developed disseminated MCMV infection concomitant with the manifestations of GVHD. Dissemination was accompanied by accelerated mortality. We demonstrate that MCMV reactivation and dissemination was modulated by MCMV-specific antibodies, thus demonstrating in vivo protective activity of antiviral antibodies. However, the efficacy of serum therapy required repetitive doses of high titer immune serum secondary to the shortened serum half-life of IgG in animals with GvHD. In a complementary approach, treatment of GVHD by adoptive transfer of donor-derived regulatory T cells facilitated production of MCMV-specific antibodies from newly developing donor-derived B cells. Together, our findings strongly suggest that antibodies play a major role in controlling recurrent MCMV infection that follows GVHD and argue for reassessing the potential of antibody treatments as well as therapeutic strategies that enhance de novo antibody development against HCMV.
Martina Seefried, Nadine Hundhausen, Irena Kroeger, Maike Büttner-Herold, Petra Hoffmann, Matthias Edinger, Evelyn Ullrich, Friederike Berberich-Siebelt, William J. Britt, Michael Mach, Thomas H. Winkler
Primary atopic disorders are a group of inborn errors of immunity that skew the immune system toward severe allergic disease. Defining the biology underlying these extreme monogenic phenotypes reveals shared mechanisms underlying common polygenic allergic disease and identifies potential drug targets. Germline gain-of-function (GOF) variants in JAK1 are a cause of severe atopy and eosinophilia. Modeling the JAK1GOF (p.A634D) variant in both zebrafish and human induced pluripotent stem cells (iPSCs) revealed enhanced myelopoiesis. RNA-Seq of JAK1GOF human whole blood, iPSCs, and transgenic zebrafish revealed a shared core set of dysregulated genes involved in IL-4, IL-13, and IFN signaling. Immunophenotypic and transcriptomic analysis of patients carrying a JAK1GOF variant revealed marked Th cell skewing. Moreover, long-term ruxolitinib treatment of 2 children carrying the JAK1GOF (p.A634D) variant remarkably improved their growth, eosinophilia, and clinical features of allergic inflammation. This work highlights the role of JAK1 signaling in atopic immune dysregulation and the clinical impact of JAK1/2 inhibition in treating eosinophilic and allergic disease.
Catherine M. Biggs, Anna Cordeiro-Santanach, Sergey V. Prykhozhij, Adam P. Deveau, Yi Lin, Kate L. Del Bel, Felix Orben, Robert J. Ragotte, Aabida Saferali, Sara Mostafavi, Louie Dinh, Darlene Dai, Katja G. Weinacht, Kerry Dobbs, Lisa Ott de Bruin, Mehul Sharma, Kevin Tsai, John J. Priatel, Richard A. Schreiber, Jacob Rozmus, Martin C.K. Hosking, Kevin E. Shopsowitz, Margaret L. McKinnon, Suzanne Vercauteren, Michael Seear, Luigi D. Notarangelo, Francis C. Lynn, Jason N. Berman, Stuart E. Turvey
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