bluuebunny/crossref_metadata_2025_split huggingface dataset:
P-Selectin Glycoprotein Ligand-1 Is Essential for Adhesion to P-Selectin But Not E-Selectin in Stably Transfected Hematopoietic Cell Lines
Authors: Snapp Karen R. , Wagers Amy J. , Craig Ron , Stoolman Lloyd M. , Kansas Geoffrey S. 
Published: October 2019

AbstractP-selectin (CD62P) is a member of the selectin family of adhesion molecules involved in the regulation of leukocyte traffic. P-selectin glycoprotein ligand-1 (PSGL-1) is a mucin-like molecule that is thought to be a primary ligand for P-selectin. The interaction of P-selectin with PSGL-1 results in leukocyte rolling and recruitment of leukocytes to sites of inflammation and tissue injury. However, expression of PSGL-1 protein alone is insufficient for binding to P-selectin. Several posttranslational modifications of PSGL-1, including sialylation, sulfation, and fucosylation by α1,3-fucosyltransferase(s) (FucT), are required for functional interaction with P-selectin. Recently, several groups have reported that PSGL-1 might also serve as a ligand for E-selectin. Differential posttranslational modifications of PSGL-1 may determine whether it can interact with either P- or E-selectin or both. To determine whether PSGL-1 is essential for adhesion to P- or E-selectin, we have constructed and analyzed a panel of stably transfected K562 cells. K562 cells express FucT-IV but not FucT-VII or PSGL-1, and do not bind to either E- or P-selectin. K562 cells transfected with PSGL-1 cDNA also did not bind to either P- or E-selectin. Binding to P-selectin occurred only when K562 cells were cotransfected with both FucT-VII and PSGL-1. In contrast, expression of FucT-VII alone was sufficient for E-selectin binding. These data demonstrate that expression of PSGL-1 is not required for adhesion of a stably transfected hematopoietic cell line to E-selectin, and suggest that FucT-IV alone cannot properly modify PSGL-1, expressed in transfected K562 cells, to bind P-selectin.
Thrombotic Thrombocytopenic Purpura and Sporadic Hemolytic-Uremic Syndrome Plasmas Induce Apoptosis in Restricted Lineages of Human Microvascular Endothelial Cells
Authors: Mitra Debashis , Jaffe Eric A. , Weksler Babette , Hajjar Katherine A. , Soderland Carl , Laurence Jeffrey 
Published: October 2019

AbstractThrombotic thrombocytopenic purpura (TTP) and sporadic hemolytic-uremic syndrome (HUS) are thrombotic microangiopathies that occur in the absence of an inflammatory response. Ultrastructural features of tissues involved in TTP/sporadic HUS suggest an apoptotic process. Consistent with these findings, we observed that TTP plasmas induce apoptosis in primary human endothelial cells (EC) of dermal microvascular but not umbilical vein origin (Laurence et al, Blood 87:3245, 1996). We now document the ability of plasmas from both TTP and sporadic HUS patients, but not from a patient with childhood/diarrhea-associated HUS, to induce apoptosis and expression of the apoptosis-associated molecule Fas (CD95) in restricted lineages of microvascular EC. EC of small vessel dermal, renal, and cerebral origin were susceptible to induction of Fas and an apoptotic cell death. In contrast, microvascular EC of pulmonary and hepatic origin, as well as EC of a large vessel, coronary artery, were resistant to both processes. This dichotomy parallels the in vivo pathology of TTP/sporadic HUS, with notable sparing of the pulmonary and hepatic microvasculature. Apoptotic EC also had some features of a procoagulant phenotype, including depressed production of prostaglandin I2 (prostacyclin). These phenomena support the pathophysiologic significance of microvascular EC apoptosis in TTP, extend it to a related disorder (sporadic HUS), and suggest consideration of apoptosis inhibitors in the experimental therapeutics of these syndromes.
Specific Accumulation of Circulating Monocytes and Polymorphonuclear Leukocytes on Platelet Thrombi in a Vascular Injury Model
Authors: Kirchhofer Daniel , Riederer Markus A. , Baumgartner Hans R. 
Published: October 2019

AbstractThe adhesion of leukocytes to platelets deposited at the site of vascular injury may represent an important mechanism by which leukocytes contribute to hemostasis and thrombosis. In this study, we examined whether, in comparison with their distribution in circulating blood, certain leukocyte types are enriched at sites of platelet deposition. We used an experimental vascular injury model, in which human fibrillar collagen was exposed to anticoagulated human whole blood flowing through parallel-plate chambers (venous shear rate, 65/s). The platelet-adherent leukocytes were detached by EDTA treatment and analyzed by flow cytometry using cell-type–specific antibodies. The predominant leukocytes found in platelet thrombi were polymorphonuclear leukocytes, accounting for 76% of bound leukocytes (62% in circulating blood), whereas T and B lymphocytes did not significantly accumulate on thrombi, comprising a fraction of less than 5% (32% in circulating blood). Monocytes constituted 16% of platelet thrombus-bound leukocytes, which represents an almost fourfold enrichment as compared with their proportion in circulating blood. Almost identical results were obtained when we analyzed leukocytes adhering to platelet monolayers, which were formed by blocking glycoprotein IIb-IIIa, thus preventing platelet aggregation on top of the collagen-adherent platelets. Furthermore, leukocyte adhesion to platelet monolayers was completely inhibited by an anti-P-selectin antibody (50% inhibitory concentration, 0.3 μg/mL), whereas it reached a plateau at about 70% inhibition on platelet thrombi. This difference could be explained by a possible function of glycoprotein IIb-IIIa in leukocyte immobilization to thrombi or by the high local concentration of P-selectin in the growing thrombi. The results suggest that, because of their known abilities to promote coagulation and thrombolysis, the monocytes and polymorphonuclear leukocytes accumulating on forming platelet thrombi could play an important role in modulating thrombotic and hemostatic processes.
Clinical, Immunologic, and Genetic Features of an Autoimmune Lymphoproliferative Syndrome Associated With Abnormal Lymphocyte Apoptosis
Authors: Sneller Michael C. , Wang Jin , Dale Janet K. , Strober Warren , Middelton Lindsay A. , Choi Youngnim , Fleisher Thomas A. , Lim Megan S. , Jaffe Elaine S. , Puck Jennifer M. , Lenardo Michael J. , Straus Stephen E. 
Published: October 2019

AbstractProgrammed cell death (apoptosis) of activated lymphocytes is critical to immune homeostasis. The cell surface protein Fas (CD95) and its ligand play a pivotal role in regulating lymphocyte apoptosis, and defective expression of either Fas or Fas ligand results in marked over accumulation of mature lymphocytes and autoimmune disease in mice. The results of recent studies suggest that defective lymphocyte apoptosis caused by mutations of the Fas gene can result in a severe autoimmune lymphoproliferative syndrome (ALPS) in humans. To define the clinical, genetic, and immunologic spectrum of ALPS, 9 patients and their families were extensively evaluated with routine clinical studies, lymphocyte phenotyping, genotyping, and in vitro assays for lymphocyte apoptosis. Individual patients were followed up for 3 months to 6 years. ALPS was identified in 9 unrelated children as manifested by moderate to massive splenomegaly and lymphadenopathy, hypergammaglobulinemia, autoimmunity, B-cell lymphocytosis, and the expansion of an unusual population of CD4−CD8− T cells that express the α/β T-cell receptor (TCR). All patients showed defective lymphocyte apoptosis in vitro. Heterozygous mutations of the Fas gene were detected in 8 patients. One ALPS patient lacked a Fas gene mutation. Healthy relatives with Fas mutations were identified in 7 of 8 ALPS kindreds. These relatives also showed in vitro abnormalities of Fas-mediated lymphocyte apoptosis, but clinical features of ALPS were not present in the vast majority of these individuals. ALPS is a unique clinical syndrome in which in vitro abnormalities of lymphocyte apoptosis are associated with abnormal lymphoproliferation and autoimmunity. These findings provide evidence that apoptosis of activated lymphocytes is an important mechanism for maintaining immunologic homeostasis and self-tolerance in humans. Fas gene mutations account for impaired lymphocyte apoptosis in only a subset of patients with ALPS.
Plasmablastic Lymphomas of the Oral Cavity: A New Entity Associated With the Human Immunodeficiency Virus Infection
Authors: Delecluse H.J. , Anagnostopoulos I. , Dallenbach F. , Hummel M. , Marafioti T. , Schneider U. , Huhn D. , Schmidt-Westhausen A. , Reichart P.A. , Gross U. , Stein H. 
Published: October 2019

AbstractWe report here a series of 16 highly malignant diffuse large B-cell lymphomas of the oral cavity with unique immunohistologic features. Fifteen of these developed in human immunodeficiency virus-positive patients. All cases displayed morphologic features of diffuse large-cell lymphomas but strikingly differed from them in that they showed a minimal or absent expression of the leukocyte common antigen as well as of the B-cell antigen CD20. Instead, the tumor cells showed a constant reaction with the plasma cell characteristic antibody VS38c and a frequent reaction with the CD79a antibody. This, in conjunction with a variable expression of cytoplasmic Ig and a monoclonal rearrangement of the Ig heavy chain gene in all of the three tested cases confirmed the B-cell nature, the clonal origin, and the plasmacellular differentiation of these neoplasms. The majority of these tumors were negative for the BCL-6 protein, with the remaining cases showing only a partial and weak expression of this antigen. An association with the Epstein-Barr virus (EBV) was found in 9 of 15 tested cases showing abundant EBV-encoded nuclear RNA transcripts in the absence of EBNA-2. Five of the EBV-positive cases variably expressed LMP-1. We propose to name these tumors plasmablastic lymphomas, in accordance with their morphologic and immunohistologic features. Knowledge of this lymphoma entity is important to avoid confusion with nonlymphoid malignancies due to the lack of commonly used lymphoid markers.
Negative Regulation of the Erythropoietin Gene Expression by the GATA Transcription Factors
Authors: Imagawa Shigehiko , Yamamoto Masayuki , Miura Yasusada 
Published: October 2019

AbstractWe examined regulation of the human erythropoietin (Epo) gene through the GATA sequence in the Epo promoter and showed that Hep3B and HepG2 cells express human GATA-2 (hGATA-2) mRNA and protein. Nuclear extracts of QT6 cells transfected with hGATA-1, 2, or 3 transcription factors showed specific binding to the GATA element in the human Epo gene promoter by gel mobility shift assay. Transient transfection of Hep3B cells with hGATA-1, 2, or 3 showed that each of these transcription factors significantly decreased the level of expression of Epo mRNA as assessed by a competitive polymerase chain reaction. Transient transfection of Hep3B cells with hGATA-1, 2, and 3 and an Epo-reporter gene (growth hormone [GH]) construct showed significant inhibition of the Epo promoter. Antisense oligonucleotide for hGATA-2 transcription factor significantly increased the Epo protein in Hep3B cells under 1% O2 for 24 hours incubation. Furthermore, transient transfection of Hep3B cells with hGATA-1, 2, and 3 and an Epo-reporter gene (luciferase) construct also showed significant inhibition of the Epo promoter. However, transfection of the mutated GATA sequence of the Epo-luciferase gene with hGATA-1, 2, and 3 interfere with the inhibition of the Epo promoter. We conclude that the hGATA-1, 2, and 3 transcription factors specifically bind to the GATA element in the human Epo gene promoter and negatively regulate Epo gene expression.
Administration of a CD31-Derived Peptide Delays the Onset and Significantly Increases Survival From Lethal Graft-Versus-Host Disease
Authors: Chen Yanfei , Schlegel Paul G. , Tran Namphuong , Thompson Diana , Zehnder James L. , Chao Nelson J. 
Published: October 2019

AbstractThe CD31 monoclonal antibody, LYP21, binds to the CD31 domain 6 and inhibits the human mixed-lymphocyte reaction (MLR) in a specific and dose-dependent fashion. A synthetic CD31 peptide based on human CD31 epitope (amino acids 551 to 574) recognized by LYP21 is equally effective in inhibiting the MLR. In this study, we used the murine homolog of CD31 peptide 551 to 574 and a control peptide to study the role of CD31 molecule on T-cell activation. In vitro, CD31 peptide inhibited the MLR across several major and minor histocompatibility differences in a specific and dose-dependent fashion, similar to the results observed in the human system. Maximal inhibition was achieved at a dose of 200 μg/mL. In the cytotoxic T-lymphocyte (CTL) assay, CD31 peptide inhibited CTL responses by 97%. To study the in vivo effect of this peptide, graft-versus-host disease (GVHD) across minor histocompatibility barriers was induced in the B10.D2 (H-2d) → BALB/c (H-2d) model. BALB/c recipients received CD31 peptide (100 μg/d), or phosphate-buffered saline (PBS), or control peptide (100 μg/d) intraperitoneally (IP) for the first 5 weeks. CD31 peptide delayed onset of graft-versus-host disease and significantly increased long-term survival. Twelve of 14 mice receiving CD31 peptide survived more than 100 days after transplantation, as compared with none of 10 mice receiving PBS and none of five mice receiving control peptide (P = .0001). Long-term engraftment of allogeneic bone marrow was documented in all transplanted mice by polymerase chain reaction (PCR) analysis of microsatellite region in the interleukin (IL)-1β gene. Our data suggest that the CD31 molecule has an important functional role in T-cell activation in vitro and in vivo.
CD44-Mediated Adhesiveness of Human Hematopoietic Progenitors to Hyaluronan Is Modulated by Cytokines
Authors: Legras Stéphane , Lévesque Jean-Pierre , Charrad Rachida , Morimoto Kohji , Le Bousse Caroline , Clay Denis , Jasmin Claude , Smadja-Joffe Florence 
Published: October 2019

AbstractAdhesive interactions between CD34+ hematopoietic progenitor cells (HPC) and bone marrow stroma are crucial for normal hematopoiesis, yet their molecular bases are still poorly elucidated. We have investigated whether cell surface proteoglycan CD44 can mediate adhesion of human CD34+ HPC to immobilized hyaluronan (HA), an abundant glycosaminoglycan of the bone marrow extracellular matrix. Our data show that, although CD34+ cells strongly express CD44, only 13.3% ± 1.1% spontaneously adheres to HA. Short-term methylcellulose assay showed that HA-adherent CD34+ cells comprised granulo-monocytic and erythroid committed progenitors (19.6% ± 2.5% and 7.3% ± 1.0% of the input, respectively). More primitive progenitors, such as pre–colony-forming units, also adhered to HA. Moreover, we found that CD44-mediated adhesion of CD34+ cells to HA could be enhanced by phorbol 12-myristate 13-acetate (PMA), the function-activating anti-CD44 monoclonal antibody H90, and cytokines such as granulocyte-monocyte colony-stimulating factor, interleukin-3 (IL-3), and stem cell factor. Enhancement through PMA required several hours, was protein-synthesis–dependent, and was associated with an increase of CD44 cell surface expression, whereas stimulation of adhesion by H90 monoclonal antibody and cytokines was very rapid and without alteration of CD44 expression. H90-induced activation occurred at 4°C and lasted for at least 2 hours, whereas activation by cytokines required incubation at 37°C and was transient. These data, which show for the first time that CD34+ HPC can directly adhere to HA via CD44, point out that this adhesive interaction to HA is a process that may also be physiologically regulated by cytokines.
Hereditary Variation in Platelet Integrin α2β1 Density Is Associated With Two Silent Polymorphisms in the α2 Gene Coding Sequence
Authors: Kunicki Thomas J. , Kritzik Marcie , Annis Douglas S. , Nugent Diane J. 
Published: October 2019

AbstractThe integrin α2β1 is a receptor for collagen that plays a fundamental role in the adhesion of blood platelets to the extracellular matrix. We previously reported that platelet α2β1 levels among randomly selected individuals can vary up to 10-fold and that this correlates with differences in adhesiveness to type-I or type-III collagens. We have now found two linked, allelic polymorphisms within the coding sequence of the α2 gene that correlate with receptor density, TTT/TTC at codon Phe224 and ACA/ACG at codon Thr246. By Southern blot hybridization of specific antisense DNA probes to segments of genomic DNA that encompass each coding region, we have determined the gene frequencies of each allele in a random donor population (n = 65) to be 0.585 (TTC ... ACG) and 0.415 (TTT ... ACA). There is a statistically significant correlation between the alleles TTT ... ACA (codons 224…246) and high receptor density (n = 30; P < .002), whereas the complimentary alleles TTC ... ACG are associated with low receptor density. Heterozygous individuals express intermediate levels of this receptor, and familial studies confirm that these allelic polymorphisms are inherited characteristics. These findings prove that the level of platelet α2β1 is an inherited trait. The molecular basis for receptor density remains to be determined, but our findings establish that these silent alleles within the coding sequence of the α2 gene are linked to the genetic basis for variation in receptor density.
Specific Inhibition of Thrombin-Induced Cell Activation by the Neutrophil Proteinases Elastase, Cathepsin G, and Proteinase 3: Evidence for Distinct Cleavage Sites Within the Aminoterminal Domain of the Thrombin Receptor
Authors: Renesto Patricia , Si-Tahar Mustapha , Moniatte Marc , Balloy Viviane , Van Dorsselaer Alain , Pidard Dominique , Chignard Michel 
Published: October 2019

AbstractThe aim of this study was to investigate the inhibitory effects of human leukocyte elastase (HLE), cathepsin G (Cat G), and proteinase 3 (PR3) on the activation of endothelial cells (ECs) and platelets by thrombin and to elucidate the underlying mechanisms. Although preincubation of ECs with HLE or Cat G prevented cytosolic calcium mobilization and prostacyclin synthesis induced by thrombin, these cell responses were not affected when triggered by TRAP42-55, a synthetic peptide corresponding to the sequence of the tethered ligand (Ser42-Phe55) unmasked by thrombin on cleavage of its receptor. Using IIaR-A, a monoclonal antibody directed against the sequence encompassing this cleavage site, flow cytometry analysis showed that the surface expression of this epitope was abolished after incubation of ECs with HLE or Cat G. Further experiments conducted with platelets indicated that not only HLE and Cat G but also PR3 inhibited cell activation induced by thrombin, although they were again ineffective when TRAP42-55 was the agonist. Similar to that for ECs, the epitope for IIaR-A disappeared on treatment of platelets with either proteinase. These results suggested that the neutrophil enzymes proteolyzed the thrombin receptor dowstream of the thrombin cleavage site (Arg41-Ser42) but left intact the TRAP42-55 binding site (Gln83-Ser93) within the extracellular aminoterminal domain. The capacity of these proteinases to cleave five overlapping synthetic peptides mapping the portion of the receptor from Asn35 to Pro85 was then investigated. Mass spectrometry studies showed several distinct cleavage sites, ie, two for HLE (Val72-Ser73 and Ile74-Asn75), three for Cat G (Arg41-Ser42, Phe55-Trp56 and Tyr69-Arg70), and one for PR3 (Val72-Ser73). We conclude that this singular susceptibility of the thrombin receptor to proteolysis accounts for the ability of neutrophil proteinases to inhibit cell responses to thrombin.
Phosphatidylserine Externalization Is a Downstream Event of Interleukin-1β–Converting Enzyme Family Protease Activation During Apoptosis
Authors: Naito Mikihiko , Nagashima Kimie , Mashima Tetsuo , Tsuruo Takashi 
Published: October 2019

AbstractPhosphatidylserine (PS), a class of acidic phospholipids, normally localizes on the internal surface of cellular plasma membranes. The internal PS is externalized when cells undergo apoptosis; however, the mechanism for this is largely unknown. To study the mechanism of PS externalization during development of apoptosis, we examined the correlation between the activation of interleukin-1β–converting enzyme (ICE) family protease and PS externalization in human monocytic leukemia U937 cells and in their apoptosis-resistant variants, UK711 and UK110, after treatment with etoposide and anti-Fas antibody. We found that PS externalization accompanied the development of apoptosis and the activation of ICE family proteases in these cell lines. Furthermore, inhibitors of ICE family proteases, Z-Asp and Z-VAD, prevented apoptosis and PS externalization in etoposide-treated U937 cells. These results indicate that PS externalization is a downstream event of ICE family protease activation during apoptosis development. Because ICE family proteases play a crucial role in apoptosis, PS externalization could be a rational and useful marker for the development of apoptosis.
Specificity of Effector T Lymphocytes in Autologous Graft-Versus-Host Disease: Role of the Major Histocompatibility Complex Class II Invariant Chain Peptide
Authors: Hess Allan D. , Bright Emilie C. , Thoburn Christopher , Vogelsang Georgia B. , Jones Richard J. , Kennedy M. John 
Published: October 2019

AbstractAdministration of the immunosuppressive drug cyclosporine after autologous bone marrow transplantation induces a systemic autoimmune syndrome resembling graft-versus-host disease (GVHD). This syndrome termed autologous GVHD has significant antitumor activity. Associated with autologous GVHD is the development of T lymphocytes that recognize major histocompatibility complex (MHC) class II determinants, including self. The present studies attempted to characterize and define the molecular specificity of the effector T lymphocytes in autologous GVHD induced in patients with metastatic breast cancer. The results suggest that the effector cells associated with human autologous GVHD are CD8+ T lymphocytes expressing the α/β T-cell receptor. Additional studies show that the effector T cells recognize MHC class II antigens in association with a peptide from the invariant chain (CLIP). Pretreatment of autologous lymphoblast target cells with anti-CLIP antibody completely blocked lysis mediated by autologous GVHD effector T cells. On the other hand, force loading this peptide markedly enhanced the susceptibility of the target cells to recognition by the autoreactive T cells. The recognition of the MHC class II CLIP complex may account for the novel specificity of the effector T cells associated with human autologous GVHD. Moreover, identification of the target peptide may allow for the development of novel immunotherapeutic strategies to enhance the antitumor efficacy of autologous GVHD.