参考文献

Hematopoietic clones with leukemogenic mutations arise in healthy people as they age,but progression to acute myeloid leukemia (AML) is rare. Recent evidence suggests that the microenvironment may play an important role in modulating human AML population dynamics. To investigate this concept further,we examined the combined and separate effects of an oncogene (c-MYC) and exposure to IL3,GM-CSF and SCF on the experimental genesis of a human AML in xenografted immunodeficient mice. Initial experiments showed that normal human CD34+ blood cells transduced with a lentiviral MYC vector and then transplanted into immunodeficient mice produced a hierarchically organized,rapidly fatal and serially transplantable blast population,phenotypically and transcriptionally similar to human AML cells,but only in mice producing IL3,GM-CSF and SCF transgenically,or in regular mice in which the cells were exposed to IL3 or GM-CSF delivered using a co-transduction strategy. In their absence,the MYC+ human cells produced a normal repertoire of lymphoid and myeloid progeny in transplanted mice for many months but,upon transfer to secondary mice producing the human cytokines,the MYC+ cells rapidly generated AML. Indistinguishable diseases were also obtained efficiently from both primitive (CD34+CD38-) and late (GMPs) cells. These findings underscore the critical role that these cytokines can play in activating a malignant state in normally differentiating human hematopoietic cells in which MYC expression has been deregulated. They also introduce a robust experimental model of human leukemogenesis to further elucidate key mechanisms involved and test strategies to suppress them. View Publication

Scleroderma (SSc) is an autoimmune connective tissue disease characterized by immune dysregulation,vasculopathy,and fibrosis. We have previously demonstrated that low Fli1 expression in SSc fibroblasts and endothelial cells plays an important role in SSc pathogenesis. Cells of myeloid and lymphoid origin also express Fli1 and are dysregulated in patients with SSc,playing key roles in disease pathogenesis. However,the role for immune Fli1 in SSc is not yet clear. Our aim was to elucidate whether Fli1 contributes to the immune dysregulation seen in SSc. Comparison of the expression of Fli1 in monocytes,B- and T-cell fractions of PBMCs isolated from SSc patients and healthy controls (HC),showed an increase in Fli1 levels in monocytes. We used siRNA transfected human myeloid cells and mouse peritoneal macrophages obtained from Fli1 flox/flox LysMCre+/+ mice,and found that markers of alternative macrophage activation were increased with Fli1 deletion. Coculture of Fli1-deficient myeloid cells and primary human or mouse fibroblasts resulted in a potent induction of collagen type I,independent of TGF$\beta$ upregulation. We next analyzed global gene expression profile in response to Fli1 downregulation,to gain further insight into the molecular mechanisms of this process and to identify differentially expressed genes in myeloid cells. Of relevance to SSc,the top most upregulated pathways were hallmark IFN-$\gamma$ and IFN-$\alpha$ response. Additionally,several genes previously linked to SSc pathogenesis and fibrosis in general were also induced,including CCL2,CCL7,MMP12,and CXCL10. ANKRD1,a profibrotic transcription co-regulator was the top upregulated gene in our array. Our results show that Fli1-deficient myeloid cells share key features with cells from SSc patients,with higher expression of profibrotic markers and activation of interferon responsive genes,thus suggesting that dysregulation of Fli1 in myeloid cells may contribute to SSc pathogenesis. View Publication

Circulating tumour cell (CTC) enumeration and profiling has been established as a valuable clinical tool in many solid malignancies. A key challenge in CTC research is the limited number of cells available for study. Ex vivo CTC culture permits expansion of these rare cell populations for detailed characterisation,functional assays including drug sensitivity testing,and investigation of the pathobiology of metastases. We report for the first time the establishment and characterisation of two continuous CTC lines from patients with gastroesophageal cancer. The two cell lines (designated UWG01CTC and UWG02CTC) demonstrated rapid tumorigenic growth in immunodeficient mice and exhibit distinct genotypic and phenotypic profiles which are consistent with the tumours of origin. UWG02CTC exhibits an EpCAM+,cytokeratin+,CD44+ phenotype,while UWG01CTC,which was derived from a patient with metastatic neuroendocrine cancer,displays an EpCAM-,weak cytokeratin phenotype,with strong expression of neuroendocrine markers. Further,the two cell lines show distinct differences in drug and radiation sensitivity which match differential cancer-associated gene expression pathways. This is strong evidence implicating EpCAM negative CTCs in metastasis. These novel,well characterised,long-term CTC cell lines from gastroesophageal cancer will facilitate ongoing research into metastasis and the discovery of therapeutic targets. View Publication

Brain tumors are the leading cause of cancer-related death in children. Genomic studies have provided insights into molecular subgroups and oncogenic drivers of pediatric brain tumors that may lead to novel therapeutic strategies. To evaluate new treatments,better preclinical models adequately reflecting the biological heterogeneity are needed. Through the Children's Oncology Group ACNS02B3 study,we have generated and comprehensively characterized 30 patient-derived orthotopic xenograft models and seven cell lines representing 14 molecular subgroups of pediatric brain tumors. Patient-derived orthotopic xenograft models were found to be representative of the human tumors they were derived from in terms of histology,immunohistochemistry,gene expression,DNA methylation,copy number,and mutational profiles. In vivo drug sensitivity of targeted therapeutics was associated with distinct molecular tumor subgroups and specific genetic alterations. These models and their molecular characterization provide an unprecedented resource for the cancer community to study key oncogenic drivers and to evaluate novel treatment strategies. View Publication

The incidence of Merkel cell carcinoma (MCC),a rare and highly metastatic skin malignancy,has sharply increased in the last decade. Clinical biomarkers are urgently needed for MCC prognosis,treatment response monitoring,and early diagnosis of relapse. The clinical interest of circulating tumors cells (CTCs) has been validated in many solid cancers. The aim of this study was to compare CTC detection and characterization in blood samples of patients with MCC using the CellSearch System and the RosetteSep -DEPArray workflow,an innovative procedure to enrich,detect and isolate single CTCs. In preliminary experiments (using spiked MCC cell lines) both methods allowed detecting very few MCC cells. In blood samples from 19 patients with MCC at different stages,CellSearch detected MCC CTCs in 26{\%} of patients,and the R-D workflow in 42{\%} of patients. The detection of CTC-positive patients increased to 52{\%} by the cumulative positivity rate of both methodologies. Moreover,Merkel cell polyomavirus DNA,involved in MCC oncogenesis,was detected in tumor biopsies,but not in all single CTCs from the same patient,reflecting the tumor heterogeneity. Our data demonstrate the possibility to detect,isolate and characterize CTCs in patients with MCC using two complementary approaches. View Publication

Seasonal and pandemic influenza infection remains a major public health concern worldwide. Driving robust humoral immunity has been a challenge given preexisting,often cross-reactive,immunity and in particular,poorly immunogenic avian antigens. To overcome immune barriers,the adjuvant MF59 has been used in seasonal influenza vaccines to increase antibody titers and improve neutralizing activity,translating to a moderate increase in protection in vulnerable populations. However,its effects on stimulating antibody effector functions,including NK cell activation,monocyte phagocytosis,and complement activity,all of which have been implicated in protection against influenza,have yet to be defined. Using systems serology,we assessed changes in antibody functional profiles in individuals who received H5N1 avian influenza vaccine administered with MF59,with alum,or delivered unadjuvanted. MF59 elicited antibody responses that stimulated robust neutrophil phagocytosis and complement activity. Conversely,vaccination with MF59 recruited NK cells poorly and drove moderate monocyte phagocytic activity,both likely compromised because of the induction of antibodies that did not bind FCGR3A. Collectively,defining the humoral antibody functions induced by distinct adjuvants may provide a path to designing next-generation vaccines that can selectively leverage the humoral immune functions,beyond binding and neutralization,resulting in better protection from infection. View Publication

During viral infections viruses express molecules that interfere with the host-cell death machinery and thus inhibit cell death responses. For example the viral FLIP (vFLIP) encoded by Kaposi's sarcoma-associated herpesvirus interacts and inhibits the central cell death effector,Caspase-8. In order to analyze the impact of anti-apoptotic viral proteins,like vFlip,on liver physiology in vivo,mice expressing vFlip constitutively in hepatocytes (vFlipAlbCre+) were generated. Transgenic expression of vFlip caused severe liver tissue injury accompanied by massive hepatocellular necrosis and inflammation that finally culminated in early postnatal death of mice. On a molecular level,hepatocellular death was mediated by RIPK1-MLKL necroptosis driven by an autocrine TNF production. The loss of hepatocytes was accompanied by impaired bile acid production and disruption of the bile duct structure with impact on the liver-gut axis. Notably,embryonic development and tissue homeostasis were unaffected by vFlip expression. In summary our data uncovered that transgenic expression of vFlip can cause severe liver injury in mice,culminating in multiple organ insufficiency and death. These results demonstrate that viral cell death regulatory molecules exhibit different facets of activities beyond the inhibition of cell death that may merit more sophisticated in vitro and in vivo analysis. View Publication

We identified individuals with variations in ACTL6B,a component of the chromatin remodeling machinery including the BAF complex. Ten individuals harbored bi-allelic mutations and presented with global developmental delay,epileptic encephalopathy,and spasticity,and ten individuals with de novo heterozygous mutations displayed intellectual disability,ambulation deficits,severe language impairment,hypotonia,Rett-like stereotypies,and minor facial dysmorphisms (wide mouth,diastema,bulbous nose). Nine of these ten unrelated individuals had the identical de novo c.1027G{\textgreater}A (p.Gly343Arg) mutation. Human-derived neurons were generated that recaptured ACTL6B expression patterns in development from progenitor cell to post-mitotic neuron,validating the use of this model. Engineered knock-out of ACTL6B in wild-type human neurons resulted in profound deficits in dendrite development,a result recapitulated in two individuals with different bi-allelic mutations,and reversed on clonal genetic repair or exogenous expression of ACTL6B. Whole-transcriptome analyses and whole-genomic profiling of the BAF complex in wild-type and bi-allelic mutant ACTL6B neural progenitor cells and neurons revealed increased genomic binding of the BAF complex in ACTL6B mutants,with corresponding transcriptional changes in several genes including TPPP and FSCN1,suggesting that altered regulation of some cytoskeletal genes contribute to altered dendrite development. Assessment of bi-alleic and heterozygous ACTL6B mutations on an ACTL6B knock-out human background demonstrated that bi-allelic mutations mimic engineered deletion deficits while heterozygous mutations do not,suggesting that the former are loss of function and the latter are gain of function. These results reveal a role for ACTL6B in neurodevelopment and implicate another component of chromatin remodeling machinery in brain disease. View Publication

Drug-induced gastrointestinal toxicity (GIT) is a common treatment-emergent adverse event that can negatively impact dosing,thereby limiting efficacy and treatment options for patients. An in vitro assay of GIT is needed to address patient variability,mimic the microphysiology of the gut,and accurately predict drug-induced GIT. Primary human ileal organoids (termed 'enteroids') have proven useful for stimulating intestinal stem cell proliferation and differentiation to multiple cell types present in the gut epithelium. Enteroids have enabled characterization of gut biology and the signaling involved in the pathogenesis of disease. Here,enteroids were differentiated from four healthy human donors and assessed for culture duration-dependent differentiation status by immunostaining for gut epithelial markers lysozyme,chromogranin A,mucin,and sucrase isomaltase. Differentiated enteroids were evaluated with a reference set of 31 drugs exhibiting varying degrees of clinical incidence of diarrhea,a common manifestation of GIT that can be caused by drug-induced thinning of the gut epithelium. An assay examining enteroid viability in response to drug treatment demonstrated 90{\%} accuracy for recapitulating the incidence of drug-induced diarrhea. The human enteroid viability assay developed here presents a promising in vitro model for evaluating drug-induced diarrhea. View Publication

Exposure to thalidomide during a critical window of development results in limb defects in humans and non-human primates while mice and rats are refractory to these effects. Thalidomide-induced teratogenicity is dependent on its binding to cereblon (CRBN),the substrate receptor of the Cul4A-DDB1-CRBN-RBX1 E3 ubiquitin ligase complex. Thalidomide binding to CRBN elicits subsequent ubiquitination and proteasomal degradation of CRBN neosubstrates including SALL4,a transcription factor of which polymorphisms phenocopy thalidomide-induced limb defects in humans. Herein,thalidomide-induced degradation of SALL4 was examined in human induced pluripotent stem cells (hiPSCs) that were differentiated either to lateral plate mesoderm (LPM)-like cells,the developmental ontology of the limb bud,or definitive endoderm. Thalidomide and its immunomodulatory drug (IMiD) analogs,lenalidomide,and pomalidomide,dose-dependently inhibited hiPSC mesendoderm differentiation. Thalidomide- and IMiD-induced SALL4 degradation can be abrogated by CRBN V388I mutation or SALL4 G416A mutation in hiPSCs. Genetically modified hiPSCs expressing CRBN E377V/V388I mutant or SALL4 G416A mutant were insensitive to the inhibitory effects of thalidomide,lenalidomide,and pomalidomide on LPM differentiation while retaining sensitivity to another known limb teratogen,all-trans retinoic acid (atRA). Finally,disruption of LPM differentiation by atRA or thalidomide perturbed subsequent chondrogenic differentiation in vitro. The data here show that thalidomide,lenalidomide,and pomalidomide affect stem cell mesendoderm differentiation through CRBN-mediated degradation of SALL4 and highlight the utility of the LPM differentiation model for studying the teratogenicity of new CRBN modulating agents. View Publication

The origin and function of blood IgM+IgD+CD27+ B cells is controversial,and they are considered a heterogeneous population. Previous staining of circulating B cells of healthy donors with rotavirus fluorescent virus-like particles allowed us to differentiate two subsets of IgM+IgD+CD27+: IgMhi and IgMlo B cells. Here,we confirmed this finding and compared the phenotype,transcriptome,in vitro function,and Ig gene repertoire of these two subsets. Eleven markers phenotypically discriminated both subsets (CD1c,CD69,IL21R,CD27,MTG,CD45RB,CD5,CD184,CD23,BAFFR,and CD38) with the IgMhi phenotypically resembling previously reported marginal zone B cells and the IgMlo resembling both na{\{i}}ve and memory B cells. Transcriptomic analysis showed that both subpopulations clustered close to germinal center-experienced IgM only B cells with a Principal Component Analysis but differed in expression of 78 genes. Moreover IgMhi B cells expressed genes characteristic of previously reported marginal zone B cells. After stimulation with CpG and cytokines significantly (p {\textless} 0.05) higher frequencies (62.5{\%}) of IgMhi B cells proliferated compared with IgMlo B cells (35.37{\%}) and differentiated to antibody secreting cells (14.22{\%} for IgMhi and 7.19{\%} for IgMlo). IgMhi B cells had significantly (p {\textless} 0.0007) higher frequencies of mutations in IGHV and IGKV regions IgMlo B cells had higher usage of IGHJ6 genes (p {\textless} 0.0001) and both subsets differed in their HCDR3 properties. IgMhi B cells shared most of their shared IGH clonotypes with IgM only memory B cells and IgMlo B cells with IgMhi B cells. These results support the notion that differential expression of IgM and IgD discriminates two subpopulations of human circulating IgM+IgD+CD27+ B cells with the IgMhi B cells having similarities with previously described marginal zone B cells that passed through germinal centers and the IgMlo B cells being the least differentiated amongst the IgM+CD27+ subsets." View Publication

BACKGROUND Lymphotoxin $\beta$ receptor (LT$\beta$R) plays important roles in the development of the immune system and immune response. At the cellular level,ligand-bound LT$\beta$R activates the pro-inflammatory NF-$\kappa$B pathway but the detailed mechanisms regulating its signaling remain unknown. Understanding them is of high importance since LT$\beta$R and its ligands are promising therapeutic targets. Here,we studied the consequences of perturbed cellular cholesterol content on LT$\beta$R-induced NF-$\kappa$B signaling. METHODS To modulate cholesterol availability and/or level in lung carcinoma A549 and H2228,and endothelial HUVEC cells different treatment regimens with filipin,methyl-$\beta$-cyclodextrin and simvastatin were applied. LT$\beta$R localization was studied by confocal microscopy. The activity of LT$\beta$R-induced NF-$\kappa$B pathway was assessed by measuring the levels of NF-$\kappa$B pathway inhibitor I$\kappa$B$\alpha$ and phosphorylation of RelA transcription factor by Western blotting. The NF-$\kappa$B transcriptional response,production of chemokines and adhesion molecules were examined by qRT-PCR,ELISA,and Western blotting,respectively. Adherence of different types of primary immune cells to epithelial A549 cells and endothelial HUVECs was measured fluorometrically. Interactions of LT$\beta$R with its protein partners were investigated by immunoprecipitation. RESULTS We showed that filipin-mediated sequestration of cholesterol or its depletion from the plasma membrane with methyl-$\beta$-cyclodextrin impaired LT$\beta$R internalization and potentiated LT$\beta$R-dependent activation of the canonical branch of the NF-$\kappa$B pathway. The latter was manifested by enhanced degradation of I$\kappa$B$\alpha$ inhibitor,elevated RelA phosphorylation,substantial increase in the expression of NF-$\kappa$B target genes encoding,among others,cytokines and adhesion molecules known to play important roles in immune response. It was followed by robust secretion of CXCL8 and upregulation of ICAM1,that favored the adhesion of immune cells (NK and T cells,neutrophils) to A549 cells and HUVECs. Mechanistically,we showed that cholesterol depletion stabilized interactions of ligand-stimulated LT$\beta$R with modified forms of TRAF2 and NEMO proteins. CONCLUSIONS Our results showed that the reduction of the plasma membrane content of cholesterol or its sequestration strongly potentiated signaling outcome initiated by LT$\beta$R. Thus,drugs modulating cholesterol levels could potentially improve efficacy of LT$\beta$R-based therapies. Video abstract. View Publication