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Biomedical subjects

S F Ziegler

Publications and source records attributed to S F Ziegler.

At least 19 recordsLinked to original sources
PubMed2002

Magnitude of the inflammatory response to cardiopulmonary bypass and its relation to adverse clinical outcomes.

INTRODUCTION: Cardiopulmonary bypass (CPB) induces an inflammatory response believed to contribute to postoperative morbidity. We hypothesized that the magnitude of the inflammatory response following CPB would be associated with adverse clinical outcomes. METHODS: Twenty-nine patients had plasma TNF, IL-6, IL-8, elastase, histamine, complement C5a, and complement C3a measured by ELISA before, during, and after cardiac operations employing CPB. Inflammatory mediator levels were analyzed with respect to outcomes. RESULTS: Mediator levels peaked at 4 h post-CPB and either returned to baseline or substantially decreased by 24 h. Patients with peak mediator levels above the median for the group as a whole were classified as 'hyper-responders'; those with levels below the median were classified as 'normal responders'. While IL-8, C3a, and IL-6 levels were independently associated with adverse outcomes, TNF, histamine, and C5a levels were not. Elastase levels trended towards adverse outcomes. IL-8 'hyper-responders' experienced significantly greater postoperative weight gain and had higher IL-8 levels at 24 h (p<0.05), with trends towards renal impairment and protracted supplemental oxygen requirements. C3a 'hyper-responders' strongly trended towards increased bleeding, delayed extubation, greater postoperative weight gain, and decreased levels of independent functioning at discharge (p < or = 0.10). IL-6 'hyper-responders' experienced significantly more postoperative bleeding, delayed extubation, and higher IL-6 levels at 24 h compared to 'normal responders' (p < 0.05). They strongly trended towards greater postoperative weight gain and decreased levels of independent functioning at discharge (p < or = 0.10). CONCLUSIONS: Patients who have an exaggerated inflammatory response to CPB tend to bleed more, require more respiratory support, demonstrate greater capillary leak via weight gain, and display a decline in independent functioning relative to normal responders. Thus, it appears that the magnitude of the inflammatory response to CPB adversely influences clinical outcomes.

Aged↗
PubMed2001

The amount of scurfin protein determines peripheral T cell number and responsiveness.

In the absence of the recently identified putative transcription factor scurfin, mice develop a lymphoproliferative disorder resulting in death by 3 wk of age from a pathology that resembles TGF-beta or CTLA-4 knockout mice. In this report, we characterize mice that overexpress the scurfin protein and demonstrate that these animals have a dramatically depressed immune system. Mice transgenic for the Foxp3 gene (which encodes the scurfin protein) have fewer T cells than their littermate controls, and those T cells that remain have poor proliferative and cytolytic responses and make little IL-2 after stimulation through the TCR. Although thymic development appears normal in these mice, peripheral lymphoid organs, particularly lymph nodes, are relatively acellular. In a separate transgenic line, forced expression of the gene specifically in the thymus can alter thymic development; however, this does not appear to affect peripheral T cells and is unable to prevent disease in mice lacking a functional Foxp3 gene, indicating that the scurfin protein acts on peripheral T cells. The data indicate a critical role for the Foxp3 gene product in the function of the immune system, with both the number and functionality of peripheral T cells under the aegis of the scurfin protein.

Animals↗
PubMed2001

Scurfin (FOXP3) acts as a repressor of transcription and regulates T cell activation.

We have recently identified and cloned Foxp3, the gene defective in mice with the scurfy mutation. The immune dysregulation documented in these mice and in humans with mutations in the orthologous gene indicates that the foxp3 gene product, scurfin, is involved in the regulation of T cell activation and differentiation. The autoimmune state observed in these patients with the immune dysregulation polyendocrinopathy, enteropathy, X-linked syndrome, or X-linked autoimmunity-allergic dysregulation syndrome also points to a critical role for scurfin in the regulation of T cell homeostasis. FOXP3 encodes a novel member of the forkhead family of transcription factors. Here we demonstrate that this structural domain is required for nuclear localization and DNA binding. Scurfin, transiently expressed in heterologous cells, represses transcription of a reporter containing a multimeric forkhead binding site. Upon overexpression in CD4 T cells, scurfin attenuates activation-induced cytokine production and proliferation. We have identified FKH binding sequences adjacent to critical NFAT regulatory sites in the promoters of several cytokine genes whose expression is sensitive to changes in SFN abundance. Our findings indicate that the ability of scurfin to bind DNA, and presumably repress transcription, plays a paramount role in determining the amplitude of the response of CD4 T cells to activation.

Animals↗
PubMed2001

Disruption of a new forkhead/winged-helix protein, scurfin, results in the fatal lymphoproliferative disorder of the scurfy mouse.

Scurfy (sf) is an X-linked recessive mouse mutant resulting in lethality in hemizygous males 16-25 days after birth, and is characterized by overproliferation of CD4+CD8- T lymphocytes, extensive multiorgan infiltration and elevation of numerous cytokines. Similar to animals that lack expression of either Ctla-4 or Tgf-beta, the pathology observed in sf mice seems to result from an inability to properly regulate CD4+CD8- T-cell activity. Here we identify the gene defective in sf mice by combining high-resolution genetic and physical mapping with large-scale sequence analysis. The protein encoded by this gene (designated Foxp3) is a new member of the forkhead/winged-helix family of transcriptional regulators and is highly conserved in humans. In sf mice, a frameshift mutation results in a product lacking the forkhead domain. Genetic complementation demonstrates that the protein product of Foxp3, scurfin, is essential for normal immune homeostasis.

Amino Acid Motifs↗
PubMed2000

Cloning of the murine thymic stromal lymphopoietin (TSLP) receptor: Formation of a functional heteromeric complex requires interleukin 7 receptor.

The cellular receptor for murine thymic stromal lymphopoietin (TSLP) was detected in a variety of murine, but not human myelomonocytic cell lines by radioligand binding. cDNA clones encoding the receptor were isolated from a murine T helper cell cDNA library. TSLP receptor (TSLPR) is a member of the hematopoietin receptor family. Transfection of TSLPR cDNA resulted in only low affinity binding. Cotransfection of the interleukin 7 (IL-7)Ralpha chain cDNA resulted in conversion to high affinity binding. TSLP did not activate cells from IL-7Ralpha(-/)- mice, but did activate cells from gammac(-/)- mice. Thus, the functional TSLPR requires the IL-7Ralpha chain, but not the gammac chain for signaling.

Amino Acid Sequence↗
PubMed2000

Cloning of a receptor subunit required for signaling by thymic stromal lymphopoietin.

Signaling by type I cytokines involves the formation of receptor homodimers, heterodimers or higher order receptor oligomers. Here we report the cloning of a type I cytokine receptor subunit that is most closely related to the common cytokine receptor gamma chain (gamma c). Binding and crosslinking experiments demonstrate that this protein is the receptor for a recently described interleukin 7 (IL-7)-like factor, thymic stromal lymphopoietin (TSLP). Binding of TSLP to the thymic stromal lymphopoietin receptor (TSLPR) is increased markedly in the presence of the IL-7 receptor alpha chain (IL-7R alpha). IL-7R alpha-expressing but not parental 32D cells proliferate in the presence of exogenous TSLP. Moreover, a combination of IL-7R alpha and TSLPR is required for TSLP-dependent activation of a STAT5-dependent reporter construct. Thus it is shown that IL-7R alpha is a component of both the IL-7 and TSLP receptors, which helps to explain why deletion of the gene that encodes IL-7R alpha affects the lymphoid system more severely than deletion of the gene encoding IL-7 does. Cloning of TSLPR should facilitate an understanding of TSLP function and its signaling mechanism.

Amino Acid Sequence↗
PubMed1999

Requirement for stat5 in thymic stromal lymphopoietin-mediated signal transduction.

Thymic stromal lymphopoietin (TSLP) is a newly identified cytokine that uniquely promotes B lymphopoiesis to the B220+/IgM+ immature B cell stage. In addition, TSLP shares many biological properties with the related cytokine IL-7. This can be explained by the finding that the receptor complexes for TSLP and IL-7 both contain the IL-7R alpha-chain; IL-7Ralpha is paired with the common gamma-chain (gammac) in the IL-7 receptor complex and the unique TSLP-R chain in the TSLP receptor complex. Although TSLP and IL-7 both induce tyrosine phosphorylation of the transcription factor Stat5, only IL-7-mediated signal transduction could be associated with activation of Janus family kinases (Jaks). Because Stat5 phosphorylation following cytokine stimulation is generally mediated by Jaks, the lack of Jak activation after TSLP treatment suggested the possibility that tyrosine-phosphorylated Stat5 may be nonfunctional. Herein, we demonstrate that TSLP induces a functional Stat5 transcription factor in that TSLP stimulation results in Stat5-DNA complex formation and transcription of the Stat5-responsive gene CIS. We also show that the TSLP receptor complex is functionally reconstituted using TSLP-R and IL-7Ralpha and that TSLP-mediated signal transduction requires Stat5. Moreover, TSLP-mediated signaling is inhibited by suppressor of cytokine signaling (SOCS)-1 and a kinase-deficient version of Tec but not by kinase-deficient forms of Jak1 and Jak2.

B-Lymphocyte Subsets↗
PubMed1999

Cellular and molecular characterization of the scurfy mouse mutant.

Mice hemizygous (Xsf/Y) for the X-linked mutation scurfy (sf) develop a severe and rapidly fatal lymphoproliferative disease mediated by CD4+CD8- T lymphocytes. We have undertaken phenotypic and functional studies to more accurately identify the immunologic pathway(s) affected by this important mutation. Flow cytometric analyses of lymphoid cell populations reveal that scurfy syndrome is characterized by changes in several phenotypic parameters, including an increase in Mac-1+ cells and a decrease in B220+ cells, changes that may result from the production of extremely high levels of the cytokine granulocyte-macrophage CSF by scurfy T cells. Scurfy T cells also exhibit strong up-regulation of cell surface Ags indicative of in vivo activation, including CD69, CD25, CD80, and CD86. Both scurfy and normal T cells are responsive to two distinct signals provided by the TCR and by ligation of CD28; scurfy cells, however, are hyperresponsive to TCR ligation and exhibit a decreased requirement for costimulation through CD28 relative to normal controls. This hypersensitivity may result, in part, from increased costimulation through B7-1 and B7-2, whose expression is up-regulated on scurfy T cells. Although the specific defect leading to this hyperactivation has not been identified, we also demonstrate that scurfy T cells are less sensitive than normal controls to inhibitors of tyrosine kinases such as genistein and herbimycin A, and the immunosuppressant cyclosporin A. One interpretation of our data would suggest that the scurfy mutation results in a defect, which interferes with the normal down-regulation of T cell activation.

Abatacept↗
PubMed1999

Thymic stromal lymphopoietin: a cytokine that promotes the development of IgM+ B cells in vitro and signals via a novel mechanism.

A novel cytokine from a thymic stromal cell line (thymic stromal lymphopoietin (TSLP)) promotes the development of B220+/IgM+ immature B cells when added to fetal liver cultures, long term bone marrow cultures, or bone marrow cells plated in semisolid medium. Because the activities of TSLP overlap with those of IL-7 in some in vitro assays, we compared the signaling mechanisms employed by TSLP and IL-7. Proliferation of a factor-dependent pre-B cell line (NAG8/7) in response to either TSLP or IL-7 was inhibited by anti-IL-7R alpha mAbs, suggesting that the functional TSLP receptor complex uses IL-7R alpha. In contrast, three different Abs to the common cytokine receptor gamma-chain had no effect on the response of these cells to TSLP, indicating that the functional TSLP receptor complex does not use the common cytokine receptor gamma-chain. Both cytokines induced activation of Stat5, but only IL-7 induced activation of the Janus family kinases Jak1 and Jak3. In fact, TSLP failed to activate any of the four known Janus family kinases, suggesting that Stat5 phosphorylation is mediated by a novel mechanism. Taken together, these data support the idea that TSLP can make unique contributions to B lymphopoiesis and indicate that it does so by mechanisms distinct from IL-7.

Animals↗
PubMed1998

Defective IL7R expression in T(-)B(+)NK(+) severe combined immunodeficiency.

Severe combined immunodeficiency (SCID) is caused by multiple genetic defects. The most common form of SCID, X-linked SCID (XSCID), results from mutations in IL2RG (ref. 4), which encodes the common cytokine receptor gamma chain (gamma(c)) that is shared by the IL-2, IL-4, IL-7, IL-9 and IL-15 receptors. In XSCID and SCID resulting from mutations in JAK3, which encodes a Janus family tyrosine kinase that couples to gamma(c) and is required for gamma(c)-dependent signalling, T- and natural killer (NK)-cells are decreased but B-cell numbers are normal (T(-)B(+)NK(-)SCID). Some SCID patients lack T cells but retain NK cells. Given diminished T-cell development in Il7- or Il7r-deficient mice and that Il/7r-deficient mice have NK cells, we hypothesized that T(-)B(+)NK(+) SCID might result from defective IL-7 signalling, although apparent differences in the role of the IL-7/IL-7R pathway in humans and mice in T-cell and B-cell development have been suggested. We now demonstrate that defective IL7R expression causes T(-)B(+)NK(+) SCID, indicating that the T-cell, but not the NK-cell, defect in XSCID results from inactivation of IL-7Ralpha signalling.

Animals↗
PubMed1996

Molecular characterization of a nonneuronal human UNC18 homolog.

A cDNA clone encoding a human homolog of the Caenorhabditis elegans unc-18 gene was identified following random sequencing of clones from IL-2-activated human NK cells. This cDNA clone is related to the nonneuronal Munc-18b and so has been called Hunc-18b. The Hunc-18b transcripts were found in most human tissues, with the exception of brain and skeletal muscle, and in cells from all lymphoid lineages. The Hunc-18b gene was localized to human chromosome 19p13.2-p13.3, and the mouse homolog, Munc-18b, was mapped to the proximal region of mouse Chromosome 8.

Amino Acid Sequence↗
PubMed1995

Granulocyte colony-stimulating factor rapidly activates a distinct STAT-like protein in normal myeloid cells.

Binding of granulocyte colony-stimulating factor (G-CSF) to normal myeloid cells activates the protein tyrosine kinases Lyn and Syk and results in the immediate early upregulation of G-CSF receptor (R) mRNA. In our studies of the signaling pathways activated by G-CSF that are coupled to proliferation and differentiation of myeloid cells, we examined whether G-CSF activated a latent transcription factor belonging to the STAT protein family. Electrophoretic mobility shift assays (EMSAs) of nuclear extracts from G-CSF-stimulated human myeloid cells showed the rapid activation of a DNA-binding protein that bound to the high-affinity serum-inducible element (hSIE) and migrated with mobility similar to serum inducible factor (SIF)-A (Stat3 homodimer). The G-CSF-stimulated SIF-A complex (G-SIF-A) did not bind to duplex oligonucleotides used to purify and characterize other Stat proteins (Stat1-6). In addition, antibodies raised against Stat1-6 failed to supershift the G-SIF-A complex or interfere with its formation. Based on its binding to the hSIE and lack of antigenic cross-reactivity with other known STAT proteins that bind to this element, it is likely that G-SIF-A is composed of a distinct member of the STAT protein family. EMSAs of whole-cell extracts prepared from cell lines containing full-length and truncated mutants of the G-CSFR showed that activation of G-SIF-A did not correlate with proliferation; rather, optimal activation requires the distal half of the cytosolic domain of the G-CSFR that is essential for differentiation. Activation of G-SIF-A, therefore, may be an early G-CSFR-coupled event that is critical for myeloid maturation.

B-Lymphocytes↗
PubMed1995

Distinct regions of the granulocyte colony-stimulating factor receptor are required for tyrosine phosphorylation of the signaling molecules JAK2, Stat3, and p42, p44MAPK.

The protein tyrosine kinases JAK1 and JAK2 are phosphorylated tyrosine after the interaction of granulocyte colony-stimulating factor (G-CSF) with its transmembrane receptor. So too is Stat3, a member of the STAT family of transcriptional activators thought to be activated by the JAK kinases. Truncated G-CSF receptor (G-CSF-R) mutants were used to determine the different regions of the cytoplasmic domain necessary for tyrosine phosphorylation of the signaling molecules JAK2, Stat3, and p42, p44MAPK. We have shown that G-CSF-induced tyrosine phosphorylation and kinase activation of JAK2 requires the membrane proximal 57 amino acids of the cytoplasmic domain. In contrast, maximal Stat3 tyrosine phosphorylation required amino acids 96 to 183 of the G-CSF-R cytoplasmic domain, Stat3 DNA binding could occur with a receptor truncated 96 amino acids from the transmembrane domain and containing a single tyrosine residue, but was reduced in comparison with the full-length receptor. Together with the tyrosine phosphorylation of Stat3, this finding suggests that additional Stat3 does not appear to be required for proliferation. MAP kinase tyrosine phosphorylation correlated with both the proliferative response and JAK2 activation.

Amino Acid Sequence↗
PubMed1995

Modulation of human G-CSF receptor mRNA and protein in normal and leukemic myeloid cells by G-CSF and retinoic acid.

Granulocyte colony-stimulating factor (G-CSF) is produced by several cell types throughout the body and has a variety of effects on neutrophils and their precursors, which are mediated by binding to its receptor. It is not yet known what physiologic factors modulate G-CSF receptor mRNA expression in these cells. We studied the effect of G-CSF on freshly isolated neutrophils and bone marrow cells from normal human subjects and on myeloid leukemic cell lines. We found that G-CSF receptor mRNA levels were maintained by G-CSF in neutrophils but not in bone marrow cells. Of the leukemic cell lines tested, K562 and BV173, both of which contain the bcr-abl translocation, neither expressed G-CSF receptor mRNA. Whereas G-CSF did not affect mRNA levels for its receptor in myeloid leukemic cell lines, exposure of the acute promyelocytic cell line, NB4, to all-trans retinoic acid induced a striking increase in G-CSF receptor mRNA expression and resulted in increased G-CSF receptor surface expression. The effect of retinoic acid on G-CSF receptor mRNA on NB4 cells occurred early, before morphologic evidence of differentiation, and required protein synthesis. All-trans retinoic acid also upregulated G-CSF receptor mRNA in the myeloid leukemia cell line HL-60. Thus, maintenance of G-CSF receptor on neutrophils by G-CSF may extend the duration of ligand responsiveness. Furthermore, the ability of retinoic acid to up-regulate G-CSF receptor may account for the synergistic effect of G-CSF and retinoic acid in differentiation induction of acute promyelocytic leukemia.

Gene Expression Regulation↗
PubMed1995

Molecular characterization of the pan-B cell antigen CDw78 as a MHC class II molecule by direct expression cloning of the transcription factor CIITA.

Antibodies against a pan-B cell-surface marker have been statistically clustered to define the CDw78 antigen. Molecular characterization of the CDw78 antigen was performed to determine its functional role in T and B cell interactions. Screening a direct expression cDNA library, made from the Epstein-Barr virus-transformed, B lymphoblastoid cell line MP-1 with an anti-CDw78 mAb, we have isolated a 3.8 kb cDNA encoding the transcription factor CIITA, previously shown to transactivate human MHC class II expression. Using several anti-CD78 mAb, we observed induced expression of the CDw78 antigen on the surface of monkey CV-1/EBNA cells transfected with the CIITA cDNA clone. Apparently, recombinant human CIITA can regulate the expression of monkey MHC class II which is recognized by anti-human CDw78 mAb. The anti-human CDw78 mAb seem to recognize a monomorphic determinant of MHC class II. Expression of recombinant human MHC class II antigens in CV-1/EBNA cells was recognized by a panel of CDw78 mAb, as well as by anti-human MHC class II mAb. These data show that the CDw78 antigen is expressed as part of the MHC class II molecule and appears similar if not identical to the alpha beta heterodimeric MHC class II antigen.

Amino Acid Sequence↗
PubMed1994

Early lymphocyte expansion is severely impaired in interleukin 7 receptor-deficient mice.

Interleukin 7 (IL-7) stimulates the proliferation of B cell progenitors, thymocytes, and mature T cells through an interaction with a high affinity receptor (IL-7R) belonging to the hematopoietin receptor superfamily. We have further addressed the role of IL-7 and its receptor during B and T cell development by generating mice genetically deficient in IL-7R. Mutant mice display a profound reduction in thymic and peripheral lymphoid cellularity. Analyses of lymphoid progenitor populations in IL-7R-deficient mice define precisely those developmental stages affected by the mutation and reveal a critical role for IL-7R during early lymphoid development. Significantly, these studies indicate that the phase of thymocyte expansion occurring before the onset of T cell receptor gene rearrangement is critically dependent upon, and mediated by the high affinity receptor for IL-7.

Animals↗
PubMed1994

Signaling by the cytoplasmic domain of hematopoietin receptors involves two distinguishable mechanisms in hepatic cells.

The receptor for granulocyte colony stimulating factor (G-CSFR) and chimeric receptors consisting of the extracellular domain of G-CSFR and the transmembrane and cytoplasmic domain of the leukemia inhibitory factor receptor, gp130, or c-mpl function as homodimeric complexes. These receptors mediate a similar stimulation of gene transcription via separate regulatory elements of acute phase plasma protein genes. To identify the receptor regions within the cytoplasmic domains necessary for transcriptional regulation, the receptors were transiently expressed in rat hepatoma cells. Each receptor form reconstituted G-CSF-induced expression of a chloramphenicol acetyltransferase gene construct containing the cytokine response element of the rat alpha 1-acid glycoprotein gene. This regulation required the presence of two conserved sequence motifs (referred to as box 1 and box 2) in the cytoplasmic domains of each receptor. With the exception of G-CSFR-MPL chimera, the receptors also mediated a similarly high stimulation via the IL-6 response element of the rat beta-fibrinogen and hemopexin genes. Regulation of the IL-6 response element required, however, in addition to boxes 1 and 2, a third sequence motif (box 3). This motif is absent in the cytoplasmic domain of c-mpl, possibly explaining its inability to activate the IL-6 response element. When cells which express receptor forms with prominent box 3 function were treated with suramin, a ligand-independent gene stimulation via the IL-6 response element was observed. The suramin effect probably involves a receptor dimerization mediated by the extracellular G-CSFR domain and by the intracellular regions that include box 3.

Acute-Phase Proteins↗