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Biomedical subjects

S Ruhl

Publications and source records attributed to S Ruhl.

At least 19 recordsLinked to original sources
PubMed2005

Proteins in whole saliva during the first year of infancy.

During the first year of an infant's life, the oral environment is subject to drastic changes that coincide with the eruption of teeth. Proteins in saliva are important for protecting oral surfaces and provide receptors for bacterial adhesins. The objective of this longitudinal study was to monitor the general composition and expression of proteins in whole saliva of infants, to prove the hypothesis that expression of certain proteins changes during infant development, and might be associated with tooth eruption. The results showed a remarkable constancy in the overall pattern of salivary proteins and glycoproteins during infancy. Exceptions were the mucins and albumin. The mucins are expressed differentially, with first MUC7 and later MUC5B being predominant. Albumin, a marker of serum leakage, started to rise in whole saliva preceding tooth eruption. Thus, the expression of only few proteins appears to be changed during infant development.

Albumins↗
PubMed2004

Salivary proteins and cytokines in drug-induced gingival overgrowth.

Little is known about the involvement of saliva in gingival overgrowth (GO). It was hypothesized that, in this situation, the composition of saliva is altered. Thus, proteins, albumin, cytokines, and growth factors in whole and glandular saliva were investigated. Differences between glandular and gingival contributions to the composition of saliva were explored in patients medicated with cyclosporin who exhibited GO (responders), those without GO (non-responders), and non-medicated subjects (controls). In whole saliva, interleukin-1alpha (IL-1alpha), IL-6, IL-8, epidermal growth factor (EGF), nerve growth factor (NGF), and albumin were detected, but in glandular saliva only EGF and NGF were identified. Albumin and IL-6 differed significantly between responders and controls, although the overall profile of salivary proteins remained unchanged. Thus, inflammatory cytokines and albumin are confined to whole saliva and are associated with GO, whereas its content of EGF and NGF appears unaffected by cyclosporin.

Albumins↗
PubMed2004

Salivary receptors for the proline-rich protein-binding and lectin-like adhesins of oral actinomyces and streptococci.

Colonization of the tooth surface by actinomyces and viridans group streptococci involves the attachment of these bacteria to adsorbed salivary components of the acquired enamel pellicle. The hypothesis that this attachment depends on specific adhesins has now been assessed from the binding of bacteria with well-defined adhesive properties to blots of SDS-PAGE-separated parotid and submandibular-sublingual (SM-SL) saliva. Streptococcus sanguis and type 2 fimbriated Actinomyces naeslundii, which bound terminal sialic acid and Galbeta1-3GalNAc, respectively, recognized only a few SM-SL salivary components, primarily MG2. In contrast, type 1 fimbriated A. naeslundii and S. gordonii, which bound purified proline-rich proteins (PRPs), recognized several other components from both SM-SL and parotid saliva. Significantly, bacteria that lacked PRP-binding and the lectin-like activities detected by binding to MG2 failed to bind any immobilized salivary component. These findings suggest the involvement of specific adhesins in bacterial recognition of many adsorbed salivary proteins and glycoproteins.

Actinomyces↗
PubMed2002

Adhesion of viridans group streptococci to sialic acid-, galactose- and N-acetylgalactosamine-containing receptors.

The binding of 10 viridans group streptococci to sialic acid-, galactose (Gal)- and N-acetylgalactosamine (GalNAc)-containing receptors was defined by analysis of the interactions between these bacteria and structurally defined glycoconjugates, host cells and other streptococci. All interactions with sialic acid-containing receptors were Ca(2+)-independent as they were not affected by ethyleneglycoltetraacetic acid (EGTA), whereas all interactions with Gal- and GalNAc-containing receptors were Ca(2+)-dependent. Recognition of sialic acid-, Gal- and GalNAc-containing receptors varied widely among the strains examined, in a manner consistent with the association of each of the three lectin-like activities with a different bacterial cell surface component.

Acetylgalactosamine↗
PubMed2000

Identification of polymorphonuclear leukocyte and HL-60 cell receptors for adhesins of Streptococcus gordonii and Actinomyces naeslundii.

Interactions of oral streptococci and actinomyces with polymorphonuclear leukocytes (PMNs), mediated by sialic acid- and Gal/GalNAc-reactive adhesins, respectively, result in activation of the PMNs and thereby may contribute to the initiation of oral inflammation. Sialidase treatment of PMNs or HL-60 cells abolished adhesion of Streptococcus gordonii but was required for adhesion of Actinomyces naeslundii. The same effects of sialidase were noted for adhesion of these bacteria to a major 150-kDa surface glycoprotein of either PMNs or undifferentiated HL-60 cells and to a 130-kDa surface glycoprotein of differentiated HL-60 cells. These glycoproteins were both identified as leukosialin (CD43) by immunoprecipitation with a specific monoclonal antibody (MAb). Adhesion of streptococci and actinomyces to a 200-kDa minor PMN surface glycoprotein was also detected by bacterial overlay of untreated and sialidase-treated nitrocellulose transfers, respectively. This glycoprotein was identified as leukocyte common antigen (CD45) by immunoprecipitation with a specific MAb. CD43 and CD45 both possess extracellular mucinlike domains in addition to intracellular domains that are implicated in signal transduction. Consequently, the interactions of streptococci and actinomyces with the mucinlike domains of these mammalian cell surface glycoproteins result not only in adhesion but, in addition, may represent the initial step in PMN activation by these bacteria.

Actinomyces↗
PubMed1997

A specific cell surface antigen of Streptococcus gordonii is associated with bacterial hemagglutination and adhesion to alpha2-3-linked sialic acid-containing receptors.

A Ca2+-independent lectin activity for alpha2-3-linked sialic acid-containing receptors is associated with Streptococcus gordonii DL1 (Challis) but not with a spontaneous mutant, strain D102, that specifically lacks hemagglutinating activity. Comparison of crossed-immunoelectrophoresis patterns of parent and mutant sonicated cell extracts identified a unique antigen (Hs antigen) in the parent cell extract that was purified by DEAE Sephacel column chromatography and by a wheat germ agglutinin (WGA) lectin affinity column. The purified antigen formed a single arc in crossed immunoelectrophoresis with anti-DL1 serum and migrated as a diffuse band above the 200-kDa marker in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoelectron microscopy with specific anti-Hs antibody revealed labeling of structures in the fibrillar layer of strain DL1 and no labeling of fibrillar structures on strain D102. Rabbit anti-DL1 serum and anti-Hs Fab inhibited the hemagglutinating activity of strain DL1, and the inhibition was specifically neutralized by purified Hs antigen. Anti-Hs Fab did not inhibit the hemagglutinating activities of several heterologous S. gordonii strains; however, these bacteria were agglutinated by anti-Hs immunoglobulin G and also by WGA. In contrast, two S. gordonii strains that lacked hemagglutinating activity did not react with anti-Hs antibody or with WGA. These findings associate the sialic acid-binding lectin activity of S. gordonii DL1 with a specific fibrillar antigen, which is composed of protein and WGA reactive carbohydrate, and indicate that cross-reactive antigens occur on other strains of this species that possess hemagglutinating activity.

Animals↗
PubMed1997

Specific inhibitors of bacterial adhesion: observations from the study of gram-positive bacteria that initiate biofilm formation on the tooth surface.

Oral surfaces are bathed in secretory antibodies and other salivary macromolecules that are potential inhibitors of specific microbial adhesion. Indigenous Gram-positive bacteria that colonize teeth, including viridans streptococci and actinomyces, may avoid inhibition of adhesion by host secretory molecules through various strategies that involve the structural design and binding properties of bacterial adhesins and receptors. Further studies to define the interactions of these molecules within the host environment may suggest novel approaches for the control of oral biofilm formation.

Actinomyces↗
PubMed1996

Recognition of immunoglobulin A1 by oral actinomyces and streptococcal lectins.

Actinomyces naeslundii and Streptococcus gordonii, oral bacteria that possess Gal/GalNAc- and sialic acid-reactive lectins, respectively, were adherent to immobilized secretory immunoglobulin A (IgA) and two IgA1 myeloma proteins but not to two IgA2 myeloma proteins. Apparently, O-linked oligosaccharides at the hinge region of the IgA1 heavy chain are receptors for lectin-mediated adhesion of these bacteria.

Actinomyces↗
PubMed1995

Putative glycoprotein and glycolipid polymorphonuclear leukocyte receptors for the Actinomyces naeslundii WVU45 fimbrial lectin.

Recognition of receptors on sialidase-treated polymorphonuclear leukocytes (PMNs) by the Gal/GalNAc lectin associated with the type 2 fimbriae of certain strains of actinomyces results in activation of the PMNs, phagocytosis, and destruction of the bacteria. In the present study, plant lectins were utilized as probes to identify putative PMN receptors for the actinomyces lectin. The Gal-reactive lectin from Ricinus communis (RCAI), the Gal/GalNAc-reactive lectins from R. communis (RCAII) and Bauhinia purpurea (BPA), as well as the Gal beta 1-3GalNAc-specific lectins from Arachis hypogaea (PNA) and Agaricus bisporus (ABA) inhibited killing of Actinomyces naeslundii WVU45 by sialidase-treated PMNs. These five lectins detected a 130-kDa surface-labeled glycoprotein on nitrocellulose transfers of PMN extracts separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This glycoprotein was revealed only after treatment of the transfers with sialidase, a condition analogous to the sialidase dependence of the lectin-mediated biological responses of the PMNs to the actinomyces. The mannose-reactive lectin concanavalin A did not inhibit killing of the actinomyces and failed to detect the 130-kDa glycoprotein but did block PMN-dependent killing of Escherichia coli B, a bacterium that possesses mannose-sensitive fimbriae. Therefore, the PMN glycoprotein receptor for A. naeslundii is clearly distinct from those recognized by E. coli. Two major putative glycolipid receptors were also identified by actinomyces and RCAI overlays on sialidase-treated thin-layer chromatograms of PMN gangliosides. Thus, both a 130-kDa glycoprotein and certain gangliosides are implicated in the attachment of the actinomyces to PMNs.

Actinomyces↗
PubMed1993

Interferon-gamma antagonizes interleukin-6-induced expression of interleukin-4 receptors in murine myeloid cells by a transcriptional mechanism.

The murine myeloid leukemia cell line M1 induced by interleukin-6 (IL-6) is a model system to study the differentiation of blast cells to mature macrophages. We have recently shown that IL-6 induces the expression of the IL-4 receptor (IL-4R) in these cells. In the present study we investigate the mechanism of action of interferon-gamma (IFN-gamma), an antagonist of IL-4 in numerous cells and a cofactor in both induction and suppression of myelopoiesis, on the expression of IL-4R. Flow cytometry shows that IFN-gamma downregulates the IL-6-induced expression of IL-4R whereas it has no such effect on the high-affinity receptors for monomeric IgG2a (Fc gamma RI). As demonstrated by Scatchard analysis, the number of IL-4R decreases by more than 50% after IFN-gamma treatment whereas the receptor affinity remains unchanged. Northern analysis shows that this decrease is paralleled by a decrease in IL-4R mRNA but not Fc gamma RI or lysozyme mRNA. Nuclear run-on analysis shows that IFN-gamma suppresses the IL-6-induced transcription of the IL-4R gene, whereas actinomycin-D chase experiments showed no change of IL-4R mRNA stability. Furthermore, the production of soluble IL-4R protein is suppressed by IFN-gamma as well. These data explain how IL-4R can be modulated by IFN-gamma in myeloid cells and are consistent with the myelosuppressive capacity of IFN-gamma.

Animals↗
PubMed1993

Dissociation of early and late markers of murine myeloid differentiation by interferon-gamma and interleukin-6.

Murine myeloid leukemia M1 cells undergo terminal differentiation to mature macrophages after stimulation with interleukin-6 (IL-6). This process can be monitored by measuring the expression of early markers such as the high affinity receptor for monomeric IgG2a (Fc gamma RI) and Ia antigen followed by late markers such as lysozyme production and finally morphological changes from blast cells to mature macrophages. The same early markers that are expressed on M1 cells after induction with IL-6 are also expressed on monocytic cells after activation with interferon-gamma (IFN gamma). We used IL-6 and IFN gamma to investigate whether the early stages of M1 cell differentiation could be accomplished without commitment of the cells to terminal differentiation. Cytofluorometry shows that the expression of the same early differentiation markers (Fc gamma RI and Ia antigen) that are inducible by IL-6 on M1 cells can be induced by IFN gamma as well. However, stimulation with IFN gamma, in contrast to IL-6, does not induce the late differentiation markers such as lysozyme production, phagocytic activity, and morphological changes. Northern analysis supports these findings in that expression of Fc gamma RI mRNA is induced by either cytokine, whereas expression of mRNA for lysozyme is inducible by IL-6 only. Nuclear run-on analysis reveals that the changes in steady state mRNA levels of both Fc gamma RI and lysozyme are regulated by a transcriptional mechanism. These data suggest that early stages in the process of myeloid differentiation can be separately induced by IFN gamma and thus are independent from the later events induced by IL-6.

Animals↗
PubMed1993

Soluble interleukin-4 receptor production by murine myeloid progenitor cells: induction by interleukin-6 and interferon-gamma.

Soluble cytokine receptors, molecules that can selectively modulate the effects of a single cytokine, have generated great interest both as indicators of disease and as targeted immunotherapeutic agents. However, cellular sources for soluble cytokine receptors are not well characterized and the regulation of soluble receptor production is not clear. We recently found that interleukin 6 (IL-6) induces the expression of membrane-bound interleukin 4 (IL-4) receptors (mIL-4R) in the murine myeloid leukemia M1 cell line. In the present study we show that IL-6 induces the expression and secretion of the soluble form of the IL-4 receptor (sIL-4R) in these cells as well, with the protein accumulating for up to 72 hours in the cell supernatants. This inducible production of sIL-4R protein is accompanied by the induction of mRNA specific for sIL-4R. In mature bone marrow (BM)-derived macrophages sIL-4R expression can be induced by exposure to either IL-6 or interferon-gamma (IFN gamma). The data suggest that myeloid cells exposed to inflammatory stimuli are one possible source for sIL-4R enabling them to modulate the effects of IL-4 on the immune response by the regulated production of the soluble receptor for this cytokine.

Animals↗
PubMed1992

Interleukin 1 augments the expression of the interleukin 2 receptor alpha-chain in interleukin 6-stimulated myeloid cells by a transcriptional and posttranscriptional mechanism.

We have recently shown that interleukin 6 (IL-6) induces transient expression of the alpha-chain of the interleukin 2 receptor (IL-2R alpha) in the murine leukemia myeloid M1 cell line. Others have reported that IL-6 and interleukin 1 (IL-1) synergistically enhance the expression of IL-2R alpha in T cells. Thus, in the present study, we investigated whether IL-1 affects the kinetics of IL-6-induced IL-2R alpha expression in M1 cells. By cytofluorometry, we find that surface expression of IL-2R alpha at 24 h after induction by IL-6 is strongly enhanced by IL-1. However, IL-1 does not change the transient kinetics of expression of IL-2R alpha. Binding data and Scatchard analysis support these results and show an increase from 3100 to 17,620 low-affinity IL-2 binding sites per cell without any change in affinity after induction of M1 cells by the combination of IL-6 and IL-1. By Northern analysis, we find that the increase in IL-2R alpha surface expression after treatment with IL-6 and IL-1 occurs in parallel with an increase in IL-2R alpha but not IL-2R beta mRNA expression. By nuclear run-on analysis and actinomycin-D chase experiments, we find that the increase in IL-2R alpha mRNA expression is due to both an increase in IL-2R alpha gene transcription and to an increase in IL-2R alpha mRNA stability. These data suggest that the IL-6-induced expression of IL-2R alpha can be specifically up-regulated by IL-1, however, without affecting the transient nature in expression of IL-2R alpha.

Acute Disease↗
PubMed1992

Transient expression of the IL-2 receptor alpha-chain in IL-6-induced myeloid cells is regulated by autocrine production of prostaglandin E2.

The alpha-chain of the interleukin 2 receptor (IL-2R alpha) is expressed on monocytes and macrophages after activation by bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). In the present study, we investigated whether the expression of IL-2R alpha is associated with the process of differentiation of myeloid cells to mature macrophages and how this expression is regulated. The murine myeloid M1 cell line, which can be induced by leukemia inhibitory factor (LIF) or interleukin 6 (IL-6) to differentiate from blast cells to mature macrophages, was used as a model system for myeloid differentiation. Bone marrow (BM)-derived macrophages were used as mature myeloid cells. Cytofluorometry revealed that IL-2R alpha is transiently expressed during M1 cell differentiation, with peak levels 24 h after induction by LIF or IL-6, whereas the high affinity receptor for monomeric IgG2a (FcR), a surface marker typical for macrophage differentiation, continues to rise up to 72 h. BM-derived macrophages already express FcR but not IL-2R alpha. IL-2R alpha expression is induced on these cells after treatment by IL-6 for up to 48 h. Treatment of IL-6-induced M1 cells with indomethacin permitted a sustained expression of IL-2R alpha beyond 24 h, and this effect was reversed by the addition of prostaglandin E2 (PGE2). Northern analysis showed that in M1 cells the expression of mRNA for IL-2R alpha, but not for IL-2R beta, is also transient, indicating that cell surface expression of IL-2R alpha is regulated at the mRNA level. These data show that inducers of macrophage differentiation such as LIF and IL-6 can induce a transient expression of the IL-2R alpha-chain in differentiating murine myeloid M1 cells and that autocrine production of PGE2 is involved in the control of the transient expression of this receptor. However, induction of expression of IL-2R alpha by IL-6 appears to be independent of differentiation because it can be induced on fully differentiated BM-derived macrophages as well.

Animals↗
PubMed1991

Regulation of interleukin-4 receptors on murine myeloid progenitor cells by interleukin-6.

Interleukin-4 (IL-4) is a T-cell-derived cytokine that regulates induction of proliferation of resting B cells and acts on various other immunocompetent cells, such as monocytes/macrophages and mast cells, as well as hematopoietic progenitor cells. On hematopoietic progenitor cells, cooperation with another cytokine (such as granulocyte-macrophage colony-stimulating factor [GM-CSF], G-CSF, IL-3, or IL-6) is required to render the cells responsive to IL-4. The present study was undertaken to determine if such an interaction entails induction of IL-4 receptor (IL-4R) expression. Using the murine myeloid leukemia M1 cell line and mature, bone marrow (BM)-derived macrophages, we investigated whether IL-4R expression can be induced during differentiation. We detected no high-affinity IL-4R on the surface of either cell, but with exposure to IL-6 a significant induction of IL-4R was measured on both cell types by fluorescence-activated cell sorter analysis. This increase in IL-4R was first noted 6 hours after exposure of the cells to IL-6 and continued to increase up to 48 hours. By RNase protection analysis we found that the expression of IL-4R mRNA also appeared within 6 hours, continuing to increase up to 48 hours. Nuclear run-on assays showed that this increase in steady-state level of IL-4R mRNA results from a transcriptional activation of the IL-4R gene. These data suggest that regulation of IL-4R expression by IL-6 is under transcriptional control.

Animals↗
PubMed1990

Adenosine and its derivatives control human monocyte differentiation into highly accessory cells versus macrophages.

Human peripheral blood monocytes have been found to undergo a transitory state of high accessory activity before they fully become macrophages. Time kinetics were done to follow this accessory potential. Studying the regulation of accessory activity, we have found that monocyte-derived accessory cells (m-AC) pass through two phases of development, which both are adversely controlled by cyclic nucleotides. Phase I is positively correlated by intracellular cAMP increase and can be arrested by adenosine 3';5' cyclic monophosphate (cAMP) and synergystic agents. In addition to cAMP, non-cyclic adenine nucleotides and adenosine also mimic all cAMP effects. This behavior is explained by the known presence of surface 5' nucleotidase and adenosine receptor, which in turn leads to activation of adenylate cyclase. At phase II serum is required to convert m-AC into macrophages. In the absence of serum, cells were arrested in the m-AC state. Adenine nucleotides effectively counteract the serum induction leading to the development of m-AC even in the presence of serum. Monocyte/macrophage markers such as Fc receptors and non-specific esterase strictly correlate negatively with the expression of accessory activity. Morphologically, the appearance of veils positively correlates with all experimental situations of high accessory activity. Therefore, it is evident that serum contains regulatory factors that strongly modify the accessory potency of the m-AC via the cyclic nucleotide system, thus presenting a potent immunoregulatory principle at the beginning of the immune cascade.

Adenosine↗