搜索结果: 'EasySep'

Efficient generation of antibodies by B cells is one of the prerequisites of protective immunity. B cell activation by cognate antigens via B cell receptors (BCRs),or pathogen-associated molecules through pattern-recognition receptors,such as Toll-like receptors (TLRs),leads to transcriptional and metabolic changes that ultimately transform B cells into antibody-producing plasma cells or memory cells. BCR signaling and a number of steps downstream of it rely on coordinated action of cellular membranes and the actin cytoskeleton,tightly controlled by concerted action of multiple regulatory proteins,some of them exclusive to B cells. Here,we dissect the role of Missing-In-Metastasis (MIM),or Metastasis suppressor 1 (MTSS1),a cancer-associated membrane and actin cytoskeleton regulating protein,in B cell-mediated immunity by taking advantage of MIM knockout mouse strain. We show undisturbed B cell development and largely normal composition of B cell compartments in the periphery. Interestingly,we found that MIM-/- B cells are defected in BCR signaling in response to surface-bound antigens but,on the other hand,show increased metabolic activity after stimulation with LPS or CpG. In vivo,MIM knockout animals exhibit impaired IgM antibody responses to immunization with T cell-independent antigen. This study provides the first comprehensive characterization of MIM in B cells,demonstrates its regulatory role for B cell-mediated immunity,as well as proposes new functions for MIM in tuning receptor signaling and cellular metabolism,processes,which may also contribute to the poorly understood functions of MIM in cancer. View Publication

Leukocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase plays a key role in host defense and immune regulation. Genetic defects in NADPH oxidase result in chronic granulomatous disease (CGD),characterized by recurrent bacterial and fungal infections and aberrant inflammation. Key drivers of hyper-inflammation induced by fungal cell walls in CGD are still incompletely defined. Here,we found that CGD (CYBB-null) neutrophils produced higher amounts of leukotriene B4 (LTB4) in vitro following activation with zymosan or Immune complexes,as compared to wild type (WT) neutrophils. This correlated with increased calcium influx in CGD neutrophils,which is restrained in WT neutrophils by the electrogenic activity of the NADPH oxidase. Increased LTB4 generation by CGD neutrophils was also augmented by paracrine cross-talk with the LTB4 receptor BLT1. CGD neutrophils formed more numerous and larger clusters in the presence of zymosan in vitro compared to WT,which was also LTB4- and BLT1-dependent. In zymosan-induced lung inflammation,focal neutrophil infiltrates were increased in CGD compared to WT mice and associated with higher LTB4 levels. Inhibiting LTB4 synthesis or antagonizing the BLT1 receptor following zymosan challenge reduced lung neutrophil recruitment in CGD to WT levels. Thus,LTB4 was the major driver of excessive neutrophilic lung inflammation in CGD mice in the early response to fungal cell walls,likely by a dysregulated feed-forward loop involving amplified neutrophil production of LTB4. This study identifies neutrophil LTB4 generation as a target of NADPH oxidase regulation,which could potentially be exploited therapeutically to reduce excessive inflammation in CGD. View Publication

Interpreting how multicellular interactions in the tumor affect resistance pathways to BRAF and MEK1/2 MAPK inhibitors (MAPKi) remains a challenge. To investigate this,we profiled global ligand-receptor interactions among tumor and stromal/immune cells from biopsies of MAPK-driven disease. MAPKi increased tumor-associated macrophages (TAMs) in some patients,which correlated with poor clinical response,and MAPKi coamplified bidirectional tumor-TAM signaling via receptor tyrosine kinases (RTKs) including AXL,MERTK,and their ligand GAS6. In xenograft tumors,intravital microscopy simultaneously monitored in situ single-cell activities of multiple kinases downstream of RTKs,revealing MAPKi increased TAMs and enhanced bypass signaling in TAM-proximal tumor cells. As a proof-of-principle strategy to block this signaling,we developed a multi-RTK kinase inhibitor nanoformulation that accumulated in TAMs and delayed disease progression. Thus,bypass signaling can reciprocally amplify across nearby cell types,offering new opportunities for therapeutic design. View Publication

Purpose: Despite high initial response rates with cytoreductive surgery,conventional chemotherapy and the incorporation of biologic agents,ovarian cancer patients often relapse and die from their disease. New approaches are needed to improve patient outcomes. This study was designed to evaluate the antitumor activity of NEO-201 monoclonal antibody (mAb) in preclinical models of ovarian cancer where the NEO-201 target is highly expressed. Experimental Design: Functional analysis of NEO-201 against tumor cell lines was performed by antibody-dependent cellular cytotoxicity (ADCC) assays. Binding of NEO-201 to tumor tissues and cell lines were determined by immunohistochemistry (IHC) and flow cytometry,respectively. Further characterization of the antigen recognized by NEO-201 was performed by mass spectrometry. Ovarian cancer models were used to evaluate the anti-tumor activity of NEO-201 in vivo. NEO-201 at a concentration of 250 g/mouse was injected intraperitoneally (IP) on days 1,4,and 8. Human PBMCs were injected IP simultaneously as effector cells. Results: Both IHC and flow cytometry revealed that NEO-201 binds prominently to the colon,pancreatic,and mucinous ovarian cancer tissues and cell lines. Immunoprecipitation of the antigen recognized by NEO-201 was performed in human ovarian,colon,and pancreatic cancer cell lines. From these screening,carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) and CEACAM6 were identified as the most likely targets of NEO-201. Our results confirmed that NEO-201 binds different types of cancers; the binding is highly selective for the tumor cells without cross reactivity with the surrounding healthy tissue. Functional analysis revealed that NEO-201 mediates ADCC killing against human ovarian and colorectal carcinoma cell lines in vitro. In addition,NEO-201 inhibited tumor growth in the presence of activated human PBMCs in orthotopic mouse models of both primary and metastatic ovarian cancer. Importantly,NEO-201 prolonged survival of tumor-bearing mice. Conclusions: These data suggested that NEO-201 has an antitumor activity against tumor cells expressing its antigen. Targeting an antigen expressed in tumors,but not in normal tissues,allows patient selection for optimal treatment. These findings strongly indicate that NEO-201 warrants clinical testing as both a novel therapeutic and diagnostic agent for treatment of ovarian carcinomas. A first in human clinical trial evaluating NEO-201 in adults with chemo-resistant solid tumors is ongoing at the NIH clinical Center. View Publication

The discovery of TMEM173/STING-dependent innate immunity has recently provided guidance for the prevention and management of inflammatory disorders. Here,we show that myeloid TMEM173 occupies an essential role in regulating coagulation in bacterial infections through a mechanism independent of type I interferon response. Mechanistically,TMEM173 binding to ITPR1 controls calcium release from the endoplasmic reticulum in macrophages and monocytes. The TMEM173-dependent increase in cytosolic calcium drives Gasdermin D (GSDMD) cleavage and activation,which triggers the release of F3,the key initiator of blood coagulation. Genetic or pharmacological inhibition of the TMEM173-GSDMD-F3 pathway blocks systemic coagulation and improves animal survival in three models of sepsis (cecal ligation and puncture or bacteremia with Escherichia coli or Streptococcus pneumoniae infection). The upregulation of the TMEM173 pathway correlates with the severity of disseminated intravascular coagulation and mortality in patients with sepsis. Thus,TMEM173 is a key regulator of blood clotting during lethal bacterial infections. View Publication

A continuing quest for specific inhibitors of proinflammatory cytokines brings promise for effective therapies designed for inflammatory and autoimmune disorders. Cefazolin,a safe,first-generation cephalosporin antibiotic,has been recently shown to specifically interact with interleukin 15 (IL-15) receptor subunit $\alpha$ (IL-15R$\alpha$) and to inhibit IL-15-dependent TNF-$\alpha$ and IL-17 synthesis. The aim of this study was to elucidate cefazolin activity against IL-2,IL-4,IL-15 and IL-21,i.e. four cytokines sharing the common cytokine receptor $\gamma$ chain ($\gamma$c). In silico,molecular docking unveiled two potential cefazolin binding sites within the IL-2/IL-15R$\beta$ subunit and two within the $\gamma$c subunit. In vitro,cefazolin decreased proliferation of PBMC (peripheral blood mononuclear cells) following IL-2,IL-4 and IL-15 stimulation,reduced production of IFN-$\gamma$,IL-17 and TNF-$\alpha$ in IL-2- and IL-15-treated PBMC and in IL-15 stimulated natural killer (NK) cells,attenuated IL-4-dependent expression of CD11c in monocyte-derived dendritic cells and suppressed phosphorylation of JAK3 in response to IL-2 and IL-15 in PBMC,to IL-4 in TF-1 (erythroleukemic cell line) and to IL-21 in NK-92 (NK cell line). The results of the study suggest that cefazolin may exert inhibitory activity against all of the $\gamma$c receptor-dependent cytokines,i.e. IL-2,IL-4,IL-7,IL-9,IL-15 and IL-21. View Publication

Murine models of myeloid neoplasia show how leukemia infiltration alters the hematopoietic stem cell (HSC) niche to reinforce malignancy at the expense of healthy hematopoiesis. However,little is known about the bone marrow architecture in humans and its impact on clinical outcome. Here,we dissect the bone marrow niche in patients with acute myeloid leukemia (AML) at first diagnosis. We combined immunohistochemical stainings with global gene expression analyses from these AML patients and correlated them with clinical features. Mesenchymal stem and progenitor cells (MSPCs) lost quiescence and significantly expanded in the bone marrow of AML patients. Strikingly,their HSC- and niche-regulating capacities were impaired with significant inhibition of osteogenesis and bone formation in a cell contact-dependent manner through inhibition of cytoplasmic $\beta$-catenin. Assessment of bone metabolism by quantifying peripheral blood osteocalcin levels revealed 30{\%} lower expression in AML patients at first diagnosis than in non-leukemic donors. Furthermore,patients with osteocalcin levels ≤11 ng/mL showed inferior overall survival with a 1-year survival rate of 38.7{\%} whereas patients with higher osteocalcin levels reached a survival rate of 66.8{\%}. These novel insights into the human AML bone marrow microenvironment help translate findings from preclinical models and detect new targets which might pave the way for niche-targeted therapies in AML patients. View Publication

B cell acute lymphoblastic leukemia (B-ALL) blasts hijack the bone marrow (BM) microenvironment to form chemoprotective leukemic BM niches facilitating chemoresistance and,ultimately,disease relapse. However,the ability to dissect these evolving,heterogeneous interactions among distinct B-ALL subtypes and their varying BM niches is limited with current in vivo methods. Here,we demonstrated an in vitro organotypic leukemia-on-a-chip" model to emulate the in vivo B-ALL BM pathology and comparatively studied the spatial and genetic heterogeneity of the BM niche in regulating B-ALL chemotherapy resistance. We revealed the heterogeneous chemoresistance mechanisms across various B-ALL cell lines and patient-derived samples. We showed that the leukemic perivascular endosteal and hematopoietic niche-derived factors maintain B-ALL survival and quiescence (e.g. CXCL12 cytokine signal VCAM-1/OPN adhesive signals and enhanced downstream leukemia-intrinsic NF-$\kappa$B pathway). Furthermore we demonstrated the preclinical use of our model to test niche-cotargeting regimens which may translate to patient-specific therapy screening and response prediction." View Publication

Human regulatory T (Treg) cells are essential for immune homeostasis. The transcription factor FOXP3 maintains Treg cell identity,yet the complete set of key transcription factors that control Treg cell gene expression remains unknown. Here,we used pooled and arrayed Cas9 ribonucleoprotein screens to identify transcription factors that regulate critical proteins in primary human Treg cells under basal and proinflammatory conditions. We then generated 54,424 single-cell transcriptomes from Treg cells subjected to genetic perturbations and cytokine stimulation,which revealed distinct gene networks individually regulated by FOXP3 and PRDM1,in addition to a network coregulated by FOXO1 and IRF4. We also discovered that HIVEP2,to our knowledge not previously implicated in Treg cell function,coregulates another gene network with SATB1 and is important for Treg cell-mediated immunosuppression. By integrating CRISPR screens and single-cell RNA-sequencing profiling,we have uncovered transcriptional regulators and downstream gene networks in human Treg cells that could be targeted for immunotherapies. View Publication

Detection and characterization of rare circulating tumor cells (CTCs) in patients' blood is important for the diagnosis and monitoring of cancer. The traditional way of counting CTCs via fluorescent images requires a series of tedious experimental procedures and often impacts the viability of cells. Here we present a method for label-free detection of CTCs from patient blood samples,by taking advantage of data analysis of bright field microscopy images. The approach uses the convolutional neural network,a powerful image classification and machine learning algorithm to perform label-free classification of cells detected in microscopic images of patient blood samples containing white blood cells and CTCs. It requires minimal data pre-processing and has an easy experimental setup. Through our experiments,we show that our method can achieve high accuracy on the identification of rare CTCs without the need for advanced devices or expert users,thus providing a faster and simpler way for counting and identifying CTCs. With more data becoming available in the future,the machine learning model can be further improved and can serve as an accurate and easy-to-use tool for CTC analysis. View Publication