bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of megakaryocytopoiesis by human macrophage-stimulating protein, the ligand for the RON receptor.
Authors: Banu N , Price D J , London R , Deng B , Mark M , Godowski P J , Avraham H 
Published: December 2022

Abstract
We observed that human megakaryocytes expressed the heterodimeric tyrosine kinase RON, which serves as a receptor for macrophage-stimulating protein (MSP). MSP appears to be structurally related to hepatocyte growth factor (HGF), which is a pleiotropic growth factor for a broad spectrum of tissues and cell types. The effects of human rMSP and rHGF on permanent human megakaryocytic cell lines as well as on human and murine primary marrow megakaryocytes were studied. MSP enhanced the maturation of the primary bone marrow megakaryocytes and human megakaryocytic cell lines, CMK and DAMI, as assessed by an increase in ploidy content. The increase in ploidy was blocked by specific Abs for MSP and by anti-IL-6 Abs. MSP treatment of primary human marrow megakaryocytes, DAMI cells, or CMK cells resulted in enhanced secretion of IL-6. The addition of MSP to cultures of immature murine megakaryoblasts showed a significant growth response, similar to that of exogenous IL-6. This increased growth of immature murine megakaryoblasts in response to MSP was abrogated either by Abs against MSP or by neutralizing mAbs to IL-6. HGF, over a range of concentrations (10 to 100 ng/ml) alone or in combination with IL-3, granulocyte-macrophage-CSF, or IL-6, had no effect on differentiation of human or murine marrow megakaryocytes. These results indicate that megakaryocytes express a novel tyrosine kinase receptor (RON), and that its ligand, MSP, appears capable of regulating megakaryocyte maturation, possibly via an autocrine mechanism mediated by induction of the cytokine IL-6.
Endotoxin-induced activation of the nuclear transcription factor kappa B and expression of E-selectin messenger RNA in hepatocytes, Kupffer cells, and endothelial cells in vivo.
Authors: Essani N A , McGuire G M , Manning A M , Jaeschke H 
Published: December 2022

Abstract
Endotoxin causes neutrophil sequestration in the liver and severe vascular and parenchymal cell injury. Inducible adhesion molecules such as intercellular adhesion molecule-1 and selectins are involved in neutrophil recruitment to an inflammatory site in vivo. The objective of our study was to characterize the translocation of the nuclear factor kappa B (NF-kappa B) from the cytoplasm to the nucleus (NF-kappa B activation) during endotoxemia using the electrophoretic mobility shift assay and to investigate its role in regulation of E-selectin gene transcription in liver cells in vivo. Administration of 0.5 mg/kg Salmonella enteritidis endotoxin to male Fischer rats induced a drastic but transient activation of NF-kappa B at the whole liver level. Major subunits identified were p50 (NF-kappa B1), p65 (RelA), and c-Rel, but not p52 (NF-kappa B2). Isolation of liver cells from control animals induced substantial NF-kappa B activation in Kupffer cells and endothelial cells and minor activation in hepatocytes. One hour after endotoxin treatment in vivo, NF-kappa B was uniformly activated in all isolated cells. At 5 h, NF-kappa B activation was reduced to various degrees in all cell types, with hepatocytes showing only a moderate decrease. Northern blot analysis indicated no E-selectin mRNA in all control cells; however, at 1 h, endotoxin induced E-selectin gene transcription transiently in endothelial cells and in Kupffer cells but not in hepatocytes. These data support the hypothesis that NF-kappa B activation is important for E-selectin gene transcription in hepatic vascular lining cells. However, the fact that hepatic parenchymal cells, despite NF-kappa B activation do not express E- selectin mRNA, suggests that NF-kappa B activation alone is not sufficient for E-selectin gene transcription in vivo.
Loss of high affinity transforming growth factor-beta 1 (TGF-beta 1) binding to a nephritogenic T cell results in absence of growth inhibition by TGF-beta 1 and augmented nephritogenicity.
Authors: Bailey N C , Frishberg Y , Kelly C J 
Published: December 2022

Abstract
Transforming growth factor-beta (TGF-beta) affects cellular proliferation and differentiation and has been linked to the development of pathologic extracellular matrix production characteristic of progressive renal disease. TGF-beta 1 is conventionally regarded as having growth-inhibitory activity on T lymphocytes. The growth-regulatory activity of TGF-beta 1 depends on the interaction of TGF-beta 1 with its receptors, especially the type I and II receptors. In this study, we describe a CD4+ nephritogenic T cell clone that, unlike a sister clone with an identical TCR Ag receptor, is not growth inhibited by TGF-beta 1, nor is its nephritogenicity affected by exogenous TGF-beta 1. Although this TGF-beta-resistant T cell clone expresses both type I and II TGF-beta receptors on the cell surface, the affinity of this interaction is markedly diminished compared with that of the sister T cell clone, which does undergo growth arrest in response to extracellular TGF-beta 1. The resistant T cell clone expresses one mutant allele for the type I TGF-beta receptor. This mutation consists of a leucine to glutamine substitution at codon 122, a conserved amino acid in the transmembrane domain. We speculate that this mutation alters the interaction between the type I and II TGF-beta receptors following recognition of ligand by the type II receptor.
Estrogen suppression of connective tissue deposition in a murine model of peritoneal adhesion formation.
Authors: Frazier-Jessen M R , Mott F J , Witte P L , Kovacs E J 
Published: December 2022

Abstract
Estrogen's involvement in inflammation and wound healing is poorly understood. To examine the role of estrogen in peritoneal adhesion formation, we gave ovariectomized female C57BL/6 mice time-release pellets containing placebo, 0.05 mg 17 beta-estradiol (low E2), or 5 mg 17 beta-estradiol (high E2) before i.p. injection of talc in saline or saline alone. Analyses of abdominal wall connective tissue thickness and peritoneal cell populations were performed. Talc-treated mice receiving low and high E2 replacement had a decreased amount of abdominal connective tissue deposition (29% and 65% decrease, respectively) as compared with talc-treated mice receiving placebo pellets. At high E2 replacement, the difference in connective tissue deposition was significant statistically (p less than 0.01). Immunohistochemical analysis revealed that the number of macrophages in adhesion tissue was proportionate to the amount of connective tissue present, regardless of the circulating levels of E2. Northern blot analysis of abdominal wall tissue showed that five of six talc-treated animals given placebo expressed mRNA for the murine monocyte chemoattractant protein-1 (MCP-1), JE. Conversely, only one of five talc-treated animals that received E2 replacement expressed JE/MCP-1 mRNA, suggesting that the hormone may inhibit connective tissue deposition by altering the production of chemotactic factors. Furthermore, E2 suppressed talc-induced expression of JE/MCP-1 mRNA in murine macrophages. Since macrophages play a central role in the wound healing process, these studies suggest that E2 inhibition of adhesion formation could be mediated by suppressing macrophage activation and/or recruitment to inflammatory sites.
Extrahepatic secreted complement C3 contributes to circulating C3 levels in humans.
Authors: Naughton M A , Botto M , Carter M J , Alexander G J , Goldman J M , Walport M J 
Published: December 2022

Abstract
The majority of complement protein C3 is synthesized by the liver, but many other cell types produce small amounts of functionally active C3. The overall contribution of such extrahepatic C3 production to the total circulating C3 level is unknown. Bone marrow and extrahepatic C3 productions were quantified in bone marrow transplant (BMT) and liver transplant (LT) recipients, respectively, where a mismatch for the C3 allotypes distinguished by the mAb HAV 4-1 had occurred. In the BMT group, donor-derived C3 was detected by ELISA and immunoblotting techniques. It contributed to 0.1 to 2.6% of the total circulating C3 during the immediate post-BMT period in response to inflammatory stimuli. Cell culture and immunostaining techniques demonstrated that monocytes were the source of the C3. By 6 wk following BMT, donor-derived C3 levels had decreased to below the detection limit of the assays. By contrast in the LT group, total extrahepatic C3 levels were higher (3.1-5.7% of the total circulating C3) and remained stable for up to 1 yr post-LT. This study demonstrates that extrahepatic derived C3 forms a larger proportion of the circulating C3 levels than was considered previously and that in the resting state, most of this extrahepatically derived C3 comes from nonmyeloid sources. In addition, monocytes, which in the resting state contribute negligible amounts of C3, have the potential when stimulated to contribute significantly to the total systemic C3 pool. These findings highlight the importance of locally secreted complement proteins.
Hydroxamate-based metalloprotease inhibitor blocks shedding of L-selectin adhesion molecule from leukocytes: functional consequences for neutrophil aggregation.
Authors: Bennett T A , Lynam E B , Sklar L A , Rogelj S 
Published: December 2022

Abstract
L-selectin is an adhesion molecule that mediates the recruitment of neutrophils to inflammatory sites and initiates the migration of lymphocytes into the peripheral lymph nodes. In response to cell activation, L-selectin is shed from the cell surface, and altered levels of functional soluble L-selectin are detected in the plasma of patients suffering from numerous inflammatory diseases as well as AIDS. The mechanism that regulates L-selectin shedding is poorly understood. Here we show that a hydroxamate-based metalloprotease inhibitor, N-(D,L-[2-(hydroxyaminocarbonyl)- methyl]-4-methylpentano)-L-3-(tert-butyl)-alanyl-L-alanine, 2-aminoethyl amide, which blocks leukocyte TNF, TNF receptor, and IL-6 receptor release, also inhibits L-selectin shedding from neutrophils, eosinophils, and lymphocytes. Moreover, we show that such inhibition of L-selectin shedding profoundly affects neutrophil aggregation and permits reaggregation in the presence of a heterologous stimulus.
Ligation of CD40 influences the function of human Ig-secreting B cell hybridomas both positively and negatively.
Authors: Bergman M C , Attrep J F , Grammer A C , Lipsky P E 
Published: December 2022

Abstract
The effect of ligation of CD40 on the proliferation and Ig secretion of a battery of human Ig-secreting hybridomas was examined to determine the regulatory activity of this surface molecule on B cells after initial activation. B cell hybridomas were generated by fusing activated peripheral blood B cells with SPAZ-4, a non-Ig-secreting fusion partner, and were cloned before analysis. All hybridomas expressed CD40 comparably. These hybridomas were stimulated with either recombinant baculovirus-expressed membrane-bound CD40L or a soluble murine CD40L/CD8 construct in the presence or the absence of various cytokines. Concentrations of CD40L that saturated 40 to 100% of CD40 induced initial homotypic aggregation followed by Fas (CD95)-independent apoptosis, with resultant decreases in growth and Ig secretion. Concentrations of CD40L that saturated 15 to 25% of CD40 also stimulated aggregation of all hybridomas. However, proliferation and Ig secretion of 9 of 13 IgM-secreting hybridomas, but none of 14 IgG- or IgA-secreting hybridomas, were enhanced by these concentrations of CD40L. These responses were independent of interactions mediated by the adhesion pair CD1la/CD18-CD54. These results indicate that the impact of CD40 ligation on human Ig-secreting hybridomas varies with the extent of CD40 engagement and depending on whether the hybridoma derived from an activated B cell that had previously undergone switch recombination.
Il-7 supports D-J but not V-DJ rearrangement of TCR-beta gene in fetal liver progenitor cells.
Authors: Tsuda S , Rieke S , Hashimoto Y , Nakauchi H , Takahama Y 
Published: December 2022

Abstract
The rearrangement of TCR-beta gene, one of the earliest events in T cell development, consists of two consecutive steps: D-J rearrangement and V-DJ rearrangement. The present study examined the signals supporting D-J beta and V-DJ beta rearrangements during early T cell development from progenitor cells that reside in fetal liver. We have found that there is an interval of 1 to 2 days between D-J beta and V-DJ beta rearrangements during the early T cell development from fetal liver progenitor cells in deoxyguanosine-treated thymus lobes. We have also found that IL-7, a cytokine expressed in the subcapsular area of the thymus, can promote D-J beta rearrangement of fetal liver progenitor cells, and that anti-IL-7 and anti-IL-7R Abs inhibit the D-J beta rearrangement and further T cell development of fetal liver progenitor cells in the thymus environment. Interestingly, unlike the thymus environment, IL-7 alone was not capable of supporting V-DJ beta rearrangement in the fetal liver cell cultures. These results indicate that D-J beta rearrangement during fetal liver-derived early T cell development is supported in the thymus by IL-7. Furthermore, the present results demonstrate that IL-7, supporting D-J beta rearrangement, does not promote V-DJ beta rearrangement of fetal liver progenitor cells, suggesting that intrathymic molecules promoting V-DJ beta rearrangement are distinct from IL-7 that supports the D-J beta rearrangement.
Identification and characterization of a C(K/R)TC motif as a common epitope present in all subtypes of hepatitis B surface antigen.
Authors: Qiu X , Schroeder P , Bridon D 
Published: December 2022

Abstract
The a determinant of hepatitis B surface antigen (HBsAg) is the most critical determinant for both diagnosis and immunoprophylaxis of the hepatitis B virus. We have used synthetic peptides and an anti-a mAb to identify a peptide sequence corresponding to amino acid residues 117 to 128 of HBsAg as an antigenic epitope contributing to the a determinant. Compared to the native protein HBsAg, the cyclic form of the peptide (aa 117-128) is only 20-fold less effective, whereas the linear form of the peptide is 160-fold less effective in the inhibition of mAb binding to HBsAg. Based on these results, we have postulated a previously unidentified disulfide bond between residue Cysl21 and Cysl24. Individual substitution of amino acids in the peptide (aa 117-128) with alanine identified three residues Cys121, Thr123, and Cys124 as the most critical residues for mAb recognition. Substitution of alanine for any one of the three residues caused a substantial loss in binding free energy (greater than 4.5 kcal/mol). Sequence analysis indicated that the C(K/R)TC motif is highly conserved among 100 subtypes and mutants of HBsAg isolates. Collectively, these results show that the cyclic C(K/R)TC motif is an essential part of the a determinant of HBsAg. Synthetic peptides containing the C(K/R)TC motif are potentially useful as alternative hepatitis B vaccines and as diagnostic reagents for the detection of the hepatitis B virus.
Modulation of endogenous IL-1 beta and IL-1 receptor antagonist results in opposing effects on HIV expression in chronically infected monocytic cells.
Authors: Goletti D , Kinter A L , Hardy E C , Poli G , Fauci A S 
Published: December 2022

Abstract
A proportion of HIV-infected individuals experience episodes of localized or systemic bacterial infections caused by Gram-negative bacteria. Many of the clinical side effects of these infections are associated with the production of proinflammatory cytokines, which are induced primarily by LPS, a constituent of the bacterial cell wall of Gram-negative bacteria. The present study examines the mechanisms involved in LPS-mediated induction of HIV expression in U1 cells, a promonocytic cell line chronically infected with HIV. Stimulation of U1 cells by LPS alone induced minimal levels of HIV expression, which was significantly enhanced by granulocyte-macrophage colony-stimulating factor (GM-CSF). Costimulation of U1 cells with LPS plus GM-CSF resulted in the accumulation of steady-state levels of HIV RNA; however, only a weak induction of HIV long terminal repeat-driven transcription, which was not associated with the activation of the cellular transcription factor nuclear factor-kappa B, was noted. Costimulation of cells with LPS plus GM-CSF induced the production of proinflammatory cytokines, IL-8, IL-1 beta and IL-6, but not TNF-alpha. IL-1 receptor antagonist (ra) inhibited LPS enhancement of HIV expression in GM-CSF-stimulated cells, suggesting that endogenous IL-1 was involved in LPS-mediated viral production. In this regard, anti-inflammatory cytokines inhibited LPS plus GM-CSF-stimulated HIV expression, and this effect closely correlated with inhibition of IL-1 beta release and, in particular, with up-regulation of endogenous IL-1ra production. Thus, the balance between an endogenously produced viral inducer (IL-1 beta ) and an inhibitor (IL-1ra) may represent an important pathway leading to modulation of HIV expression from monocytic cells.
IL-10 production is enhanced in human T cells by IL-12 and IL-6 and in monocytes by tumor necrosis factor-alpha.
Authors: Daftarian P M , Kumar A , Kryworuchko M , Diaz-Mitoma F 
Published: December 2022

Abstract
IL-10, an immunoregulatory cytokine produced by T cells and monocytes, inhibits the expression of inflammatory and hemopoietic cytokines as well as its own expression. To evaluate the regulation of IL-10 production by T cells and monocytes, we measured IL-10 levels by ELISA in supernatants of PHA-stimulated PBMC following depletion of either T cells or monocytes. IL-10 production was significantly down-regulated in both T cell- and monocyte-depleted PBMC compared with undepleted PBMC, and IL-10 production could be restored by the addition of monocyte-conditioned medium (supernatant of PHA-stimulated, T cell-depleted PBMC), suggesting that IL-10 production by T cells is regulated by a monokine(s) produced by activated monocytes. To further clarify the monokine(s) responsible for IL-10 induction, we stimulated monocyte-depleted PBMC, purified CD4+, and CD8+ T cells with PHA and measured IL-10 production by ELISA and semiquantitative reverse transcriptase-PCR following monokine(s) addition. Addition of IL-6 and IL-12 enhanced IL-10 production in monocyte-depleted PBMC in a dose-dependent and additive manner. Furthermore, anti-IL-6 and anti-IL-12 Abs neutralized the IL-10-inductive effect of monocyte-conditioned medium. Similarly, IL-12 and IL-6 induced IL-10 production by purified CD4+ and CD8+ T cells. With respect to regulation of IL-10 produced by monocytes, TNF-alpha was found to induce IL-10 production by resting as well as by LPS-stimulated purified monocytes/macrophages. Taken together, these findings suggest that IL-10 production by human T cells and monocytes is differentially regulated. IL-12 and/or IL-6 can induce the expression of IL-10 by PHA-stimulated T cells, whereas TNF-alpha induces IL-10 production by monocytes. Since IL-10 inhibits the production of IL-6, IL-12, and TNF-alpha, these results may indicate a potential mechanism of negative feedback regulation of the immune response.
Multiple interactive residues of recognition: elucidation of discontinuous epitopes with linear peptides.
Authors: Gao B , Esnouf M P 
Published: December 2022

Abstract
The discontinuous epitopes of beta-factor XIIa for three mAbs were mapped by a linear peptide-based immunoblotting technique, referred to as multiple interactive residues of recognition. The Abs were incubated with a set of overlapping synthetic peptides, deduced from the cDNA sequences of beta-factor XIIa, on a polymer membrane, and the signal was amplified by an ECL assay. Several discrete sequences of the protein were recognized by each Ab. The recognized peptides were further characterized using alanine substitution analogues and peptides of different lengths. The discontinuous epitopes found for each Ab were formed by several peptides and were composed of 20 to 31 residues. The sequence FLQEA was recognized by all three Abs and was the immunodominant peptide. Abs 201/9 and 2/15 bound to very similar discontinuous sequences, but with subtle differences. The sequences 76RLHEAFSP83, 88HDLALLRLQE97, 178GFLEG182, 146FLQEA150, and 237IRE239 formed the epitope for mAb 201/9, whereas 76RLHEAFSP83, 90LALLRLQE97, 146FLQEA150, and 235AWIREHT241 formed the epitope for Ab 2/15. The third Ab 202/7 recognized the sequences 79EAFSP83, 93LRLQE97, 133WGHQF137, and 146FLQEA150. We suggest that these sequences represent the sites to which the Abs bind. This procedure provides a sensitive and convenient tool to elucidate discontinuous epitopes for the binding of Abs, receptor ligand-binding sites, or enzyme inhibitor binding sites.
Identification, molecular cloning, biologic properties, and tissue distribution of a novel isoform of murine low-affinity IgG receptor homologous to human Fc gamma RIIB1.
Authors: Latour S , Fridman W H , Daëron M 
Published: December 2022

Abstract
A cryptic splice donor site in the first intracytoplasmic (IC) exon of the murine Fc gamma RIIB gene generates a previously unknown Fc gamma RIIB isoform. Three membrane Fc gamma RIIB polypeptides of 37, 32, and 30 kDa were immunoprecipitated by Fc gamma RIIB-specific Abs, and three Fc gamma RIIB cDNAs of 1071, 987, and 930 bp were amplified by reverse transcriptase-PCR with Fc gamma RIIB-specific oligonucleotides from the mastocytoma cells P815. The 1071-bp cDNA contains all sequences of IC exons and encodes the 37-kDa Fc gamma RIIB1 isoform. The 930-bp cDNA lacks sequences of the first IC exon and encodes the 30-kDa Fc gamma RIIB2 isoform. The 987-bp cDNA has an 84-nucleotide deletion of the first IC exon 3' sequences. When stably transfected in the lymphoma B cells IIA1.6, or in the mast cells RBL-2H3, this cDNA encoded 32-kDa Fc gamma RIIB whose biologic properties were undistinguishable from those of Fc gamma RIIB1: they inhibited B cell activation when coaggregated to B cell receptors and capped when aggregated at 37 degrees C, but failed to mediate endocytosis or phagocytosis. Sequences responsible for capping and inhibition of internalization, previously assigned to sequences encoded by the first IC exon, can thus be mapped in the 19 N-terminal residues. These residues are highly conserved in human Fc gamma RIIB1. The 87-bp first IC exon of the human gene ends by a single splice site in the downstream intron and encodes a 19-amino acid insertion. The 32-kDa Fc gamma RIIB is the murine homologue of human Fc gamma RIIB1. We propose to name it Fc gamma RIIB1'. Fc gamma RIIB1' was expressed in myeloid and lymphoid cell lines, in normal spleen cells, and in resting or LPS-activated B cells.