Hematology
Abstract
Typ515 (W515) mutations in the protein MPL are one of key driver mutations promoting BCR/ABL-negative myeloproliferative neoplasms (MPNs), but their effects on hematopoietic stem cells (HSCs) and MPN-related hematological abnormalities have not been studied in physiological contexts. Here, we established a MplW514L knock-in mouse model which largely mimics human MPLW515L mutation during hematopoiesis. The mutant mice developed an essential thrombocythemia (ET)-like MPN phenotypes, displaying excess megakaryopoiesis and thrombocytosis and progressive myelofibrosis. Mechanistically we observed that MplW514L-conditioned HSC compartment had a unique disease-initiating capacity however it did not exhibit a obvious advantage of competitive repopulation over wild-type control. Notably, single-cell analysis and flow cytometry profiles support that MplW514L expression led to a significant expansion of megakaryocyte-biased stem cell fate within the HSC pool. Finally, JAK2 inhibitor treatment phenotypically alleviated the ET signs but failed to eliminate the disease-initiating HSCs. These findings underscore the etiology of physiological expression of MPLW515L mutation in HSCs, and also provide a valuable in vivo model to evaluate potential therapeutic options for patients with MPLW515L-positive MPN.
Authors
Shujing Zhang, Jingjing Liu, yuan li, Yi Wang, Lingling Wang, Miaomiao Xu, Yanxia Li, Ge Dong, Shanshan Wang, Yanmei Li, Zhigang Cai, Baobing Zhao
Abstract
BACKGROUND. Genetically engineered porcine livers are being developed as a bridge therapy for acute liver failure, providing detoxification and restoration of hepatic protein synthesis. Severe xenograft-associated severe thrombocytopenia remains a major limitation, and human mechanistic data are scarce. METHODS. Platelet kinetics were characterized in three human decedents undergoing extracorporeal cross-circulation with transgenic porcine livers. Platelet counts, transfusion requirements, and clearance patterns were assessed to distinguish consumption from marrow suppression or hypersplenism. Antibody- and complement-directed inhibitors were administered to test immune-mediated mechanisms. Mechanistic studies focused on porcine von Willebrand factor (pVWF)–dependent platelet activation, including ex vivo blockade with the anti-VWF nanobody caplacizumab, a vWF-directed antibody fragment that prevents vWF–platelet binding. A fourth decedent received caplacizumab during porcine liver perfusion. RESULTS. In all three initial cases, 80%–90% of circulating and transfused platelets were rapidly cleared, a pattern inconsistent with marrow suppression or hypersplenism. Antibody and complement inhibition failed to ameliorate thrombocytopenia. Recipient plasma induced robust pVWF-mediated platelet activation analogous to human Type IIb von Willebrand disease, which was completely abrogated ex vivo by caplacizumab. In a fourth decedent treated with caplacizumab, aberrant platelet activation was prevented, though full hematologic recovery was limited by pre-existing disseminated intravascular coagulation (DIC). CONCLUSIONS. Early thrombocytopenia during porcine liver xenotransplantation appears to be primarily driven by pVWF-mediated platelet activation rather than by classical immune or splenic mechanisms. Targeted VWF blockade with agents such as caplacizumab may mitigate platelet loss and improve the safety profile of extracorporeal porcine liver support in acute liver failure.
Authors
Liang Zhao, Sokratis A. Apostolidis, Aae Suzuki, Amrita Sarkar, Qian Guo, Felix Li, Alex Sagar, John I. Fallon, Mohamed A. Elzawahry, Syed Hussain Abbas, Leanne Lanieri, Kristen Getchell, Susan C. Low, Kim M. Olthoff, Emma E. Furth, Brendan J. Keating, Peter Friend, Mortimer Poncz, Abraham Shaked, Charles S. Abrams
Abstract
N6-methyladenosine (m6A) is a prevalent modification of mammalian mRNA. Increasing evidence has documented diverse roles of m6A in normal cell physiology and diseases. However, its functional role in erythropoiesis remains poorly understood. In this study, we found that deletion of Mettl3 using EpoR-Cre mouse led to microcytic/hypochromic anemia due to defective erythropoiesis along with impaired hemoglobin biosynthesis. Mechanically, Mettl3 deficiency disrupted nucleotide biosynthesis which induced DNA damage, leading to apoptosis of CFU-E cells and cell cycle arrest of erythroblasts. Integrated m6A sequencing and RNA-seq analysis along with biochemical studies identified Mthfd1, a key enzyme involved in nucleotide biosynthesis, as a Mettl3 direct target gene. Furthermore, deletion of Mettl3 led to decreased expression of Mthfd1 accompanied by a shortage of nucleotides dTMP and IMP in erythroid cells. Additionally, inhibition of METTL3 in human erythroid cells led to similar phenotypic and molecular changes, indicating conserved role of METTL3 in human and murine erythropoiesis. Our findings have identified a METTL3-m6A-MTHFD1 axis that plays a critical role in erythropoiesis by maintaining genome stability of erythroid cells via regulation of nucleotide biosynthesis. These findings provide important insights into the regulatory mechanisms of erythropoiesis and may have implications for underlying the mechanisms of anemias.
Authors
Linlin Zhang, Huizhi Zhao, Shihui Wang, Xueting Wu, Donghao Liu, Hengchao Zhang, Qianqian Yang, Ying Cheng, Xiuyun Wu, Jiangwei Zhao, Shijie Zhang, Huan Zhang, Haojian Zhang, Qiaozhen Kang, Lixiang Chen, Xiuli An, Xiaoli Qu
Abstract
SEL1L is a well-known protein in the ER-associated degradation (ERAD) pathway. While it is known to be expressed in platelets, SEL1L has never been shown to play an active role. Here, we present evidence that SEL1L regulates platelet function. We first identified SEL1L through the study of Atypical Equine Thrombasthenia (AET), an autosomal recessive platelet disorder found in thoroughbred horses. A missense variant in SEL1L (c.1810A>G p.Ile604Val) was found in AET-affected horses, which we show is associated with decreased protein expression. SEL1L is intracellular in equine platelets and localizes to the surface upon activation with thrombin. Platelets from homozygous horses exhibited substantially decreased spreading on immobilized collagen. Human megakaryocytes were found to have 2 SEL1L protein isoforms that increase in expression during megakaryopoiesis, although only 1 isoform was delivered to mature platelets. Studies using inducible mouse and constitutive zebrafish KOs demonstrated that SEL1L is necessary for efficient platelet or thrombocyte (fish equivalent) adhesion to sites of endothelial injury. These data reveal a previously undescribed and conserved role for the ERAD pathway in the etiology of AET and platelet function, and GWAS data suggest that it may play a role in human platelet disorders as well.
Authors
Anna R. Dahlgren, Francesca Careddu, Jeffrey W. Norris, Christian A. Di Buduo, Livia Stanger, Reheman Adili, Erin M. Kropp, Qing Li, Michael Holinstat, Ida Biunno, Alessandra Balduini, Fern Tablin, Jordan A. Shavit, Carrie J. Finno
Abstract
BACKGROUND Chronic graft-versus-host disease (cGVHD) is a major contributor to nonrelapse mortality (NRM) following hematopoietic cell transplantation (HCT). Whether machine-learning (ML) models with biomarkers improve the accuracy for predicting future cGVHD/NRM is not established.METHODS We developed BIOPREVENT (BIOmarkers PREVENTion), a ML algorithm using data from 1,310 HCT recipients, incorporating 7 plasma proteins measured at Day 90/100 post-HCT and 9 clinical variables. Patients were divided into training and validation datasets. ML models — including CoxXGBoost, Group SCAD, Adaptive Group Lasso, Random Survival Forests, and Bayesian Additive Regression Trees (BART) — were used to estimate time-varying Area Under the ROC Curve (AUCt) at Days 180, 270, 360, and 540. Deep learning models were also evaluated.RESULTS ML models with biomarkers outperformed clinical-only models for predicting cGVHD, with BART and CoxXGBoost achieving AUCt greater than 0.65 at 1 year. For NRM, models with biomarkers achieved AUCt ranging from 0.75–0.91. Deep learning did not outperform other ML approaches. BART consistently demonstrated high predictive accuracy and was selected for the final BIOPREVENT model. Calibration curves aligned with observed values. Variable importance analysis identified MMP3 and CXCL9 as key for cGVHD prediction and IL1RL1 and sCD163 for NRM. Cumulative incidences of cGVHD and NRM differed significantly based on BIOPREVENT-defined cutpoints.CONCLUSION BIOPREVENT accurately predicts individual risk of future cGVHD and NRM using biomarkers at 3 months post-HCT. A publicly available R Shiny web application supports its clinical use. Further studies are needed to explore its role in guiding preemptive therapy.TRIAL REGISTRATION BMTCTN 0201, BMTCTN 1202, and NCT02194439.FUNDING R01CA264921, U10HL069294, U24HL138660, R01HD074587, and P01HL158505.
Authors
Michael J. Martens, Debjani Dutta, Yongzi Yu, Lisa E. Rein, Jerome Ritz, Brent R. Logan, Sophie Paczesny
Abstract
Authors
Maiko Sezaki, Tian Li, Mingzhe Pan, Zhihong Wang, Jie Bai, Justin G. Horowitz, Julia Z. Xu, Gang Huang
Abstract
Myelodysplastic syndromes (MDSs) are malignant hematopoietic stem and progenitor cell (HSPC) disorders that lead to ineffective blood production with poor outcomes. We previously showed that F-box only protein 11 (FBXO11) is downregulated in MDS, and here we report how this event contributes to disease progression. Integration of multiomics data revealed that the SCF-FBXO11 complex regulates spliceosome and ribosome components in a nucleophosmin 1 (NPM1)-centric network. FBXO11 facilitates the ubiquitylation of NPM1, whereby deletion of FBXO11 results in the reorganization of NPM1 and a de-repression of alternative splicing. Label-free total quantitative proteomics demonstrated that the FBXO11-NPM1 interactome was markedly downregulated in cells from patients with CD34+ MDS. In addition, we discovered that MYC was evicted from the FBXO11 promoter by TLR2 activation, revealing that it was a MYC target gene and explaining why FBXO11 expression was decreased in MDS. In MDS mouse models, genetic ablation of Fbxo11 exacerbated neutropenia concomitant with a profound decrease in NPM1 protein levels. Finally, we discovered rare mutations in FBXO11, which mapped to a previously unstudied functional intrinsically disordered region (IDR) in the N-terminus responsible for binding NPM1. These data support a model in which FBXO11 rewires RNA binding and ribosomal subnetworks through ubiquitylation of NPM1, ultimately restricting MDS progression.
Authors
Madeline Niederkorn, Lavanya Bezavada, Anitria Cotton, Lance E. Palmer, Lahiri Konada, Trent Hall, Vishwajeeth R. Pagala, Jinbin Zhai, Zuo-Fei Yuan, Yingxue Fu, Jacob A. Steele, Shilpa Narina, Andrew Schild, Chengzhou Wu, Sarah Aminov, Michael Schieber, Erin McGovern, Aaron B. Taylor, Sandeep Gurbuxani, Peng Xu, Peng Ji, Laura J. Janke, Anthony A. High, Guolian Kang, Shondra M. Pruett-Miller, Mitchell Weiss, Amit Verma, Raajit K. Rampal, John D. Crispino
Abstract
WHIM syndrome is an immunodeficiency caused by autosomal dominant hyperfunctional mutations in chemokine receptor CXCR4 that promote panleukopenia due to BM retention. We previously reported a preclinical gene therapy protocol involving allele-nonspecific Cxcr4 CRISPR/Cas9 inactivation, leveraging the known in vivo dominance of Cxcr4+/o (+, WT; o, inactivated) hematopoietic stem cells (HSCs) for autologous BM engraftment and leukocyte reconstitution over HSCs with other Cxcr4 genotypes. Here, we show that without BM conditioning, this approach is not able to correct leukopenia in WHIM mice. We therefore modified the protocol by adding conditioning with a non-genotoxic CD117-targeted immunotoxin, CD117-antibody-saporin-conjugate (CD117-ASC). With this change, donor-derived blood cells rapidly reached ~95% chimerism after transplantation, which was stable without adverse events for more than 400 days. Mice receiving edited HSCs showed rapid normalization of absolute myeloid cell counts, the key blood subset responsible for WHIM syndrome. In competitive transplants using equal numbers of edited and unedited donor HSCs, over 80% of blood cells originated from the edited population, predominantly with the Cxcr4+/o genotype. These results provide proof of principle that CRISPR/Cas9-mediated inactivation of the Cxcr4 disease allele, combined with non-genotoxic HSC-targeted conditioning, may offer a safe and effective gene therapy strategy generalizable to all WHIM mutations.
Authors
Ji-Liang Gao, Zhanzhuo Li, Rafael Calderon-Perez, Antonia Pavek, Lina Kim, David H. McDermott, Philip M. Murphy
Abstract
Aged individuals with somatic TP53 mutations manifest clonal hematopoiesis (CH) and are at high risk of developing myeloid neoplasms. However, the underlying mechanisms are not fully understood. Here we show that inflammatory stress confers a competitive advantage to p53 mutant hematopoietic stem and progenitor cells (HSPCs) by activating the NLRP1 inflammasome and increasing the secretion of pro-inflammatory cytokines such as IL-1β, inhibiting wild type (WT) HSPC fitness in a paracrine fashion. During aging, mutant p53 dysregulates pre-mRNA splicing in HSPCs, leading to enhanced NF-κB activation and increased secretion of IL-1β and IL-6, thereby generating a chronic inflammatory bone marrow microenvironment. Furthermore, blocking IL-1β with IL-1β neutralizing antibody or inhibiting IL-1β secretion using gasdermin D (GSDMD) inhibitor decreases the fitness of p53 mutant HSPCs. Thus, our findings uncover an important role for mutant p53 in regulating inflammatory signaling in CH and suggest that curbing inflammation may prevent the progression of TP53-mutant clonal hematopoiesis to myeloid neoplasms.
Authors
Sisi Chen, Sergio Barajas, Sasidhar Vemula, Yuxia Yang, Ed Simpson, Hongyu Gao, Rudong Li, Farzaneh Behzadnia, Sarah C. Nabinger, David A. Schmitz, Hongxia Chen, Wenjie Cai, Shiyu Xiao, Ruyue Luo, Mohammed Abdullahel Amin, Maegan L. Capitano, James P. Ropa, Aidan Fahey, Shuyi Zhou, Tiffany M. Mays, Magdalena Sotelo, Hao Pan, Sophie K. Hu, Sophia Veranga, Moiez Ali, Maria Shumilina, Reuben Kapur, Kehan Ren, Yuzhi Jia, Huiping Liu, Irum Khan, Yasmin Abaza, Jessica K. Altman, Elizabeth A. Eklund, Lucy A. Godley, Christine R. Zhang, Peng Ji, Seth L. Masters, Ben A. Croker, H. Scott Boswell, George E. Sandusky, Zhonghua Gao, Lindsey D. Mayo, Sharon A. Savage, Stephanie Halene, Yali Dou, Leonidas C. Platanias, Madina Sukhanova, Yunlong Liu, Omar Abdel-Wahab, Yan Liu
Abstract
Recent studies suggest that prediabetes is an independent risk factor for cardiovascular thrombotic events. However, the mechanisms that may promote platelet activation and thrombosis in prediabetes remain elusive. To determine mechanisms linking prediabetes and thrombosis as a function of age, we recruited prediabetic and normoglycemic Veterans in young and middle-age groups. Compared to normoglycemic subjects, platelets from those with prediabetes exhibited increased activation, mitochondrial-oxidant load, mitochondrial-membrane hyperpolarization, and greater thrombus formation ex vivo regardless of age. Preincubation of platelets with mitochondria targeted antioxidants such as superoxide dismutase (SOD) mimetic or Mito quinol (MitoQ), rescued this prothrombotic phenotype. These phenotypes were recapitulated in C57BL6/J mice exhibiting early onset of glucose intolerance when fed high fat (HF) diet for two weeks. Treatment of HF-fed mice with a SOD-mimetic or MitoQ, or genetic overexpression of catalase within mitochondria, not only lowered mitochondrial-oxidants, hyperpolarization, Ca2+ levels and platelet activation, but also protected against increased potential for carotid and pulmonary thrombosis. We also observed a bidirectional regulation of platelet activation by Ca2+ and mitochondrial oxidants. These findings support the idea that mitochondrial-oxidant dependent platelet activation induces a prothrombotic state in clinical prediabetes and preclinical models of short-term glucose intolerance and can be reversed by mitochondria-targeted antioxidants.
Authors
Azaj Ahmed, Pooja Yadav, Melissa Jensen, Katharine Geasland, Jagadish S. Swamy, Douglas R. Spitz, E. Dale Abel, Diana Jalal, Sanjana Dayal
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)