Biomedical subjects

G Frendl

Publications and source records attributed to G Frendl.

11 recordsLinked to original sources

PubMed1995

Receptors involved in carbohydrate binding modulate intestinal epithelial-neutrophil interactions.

Neutrophil (polymorphonuclear neutrophil) migration across epithelial barriers is a common morphologic feature of many diseases. Previous studies show that PMN-epithelial interactions are dependent on the PMN beta 2-integrin CD11b/18; however, nothing is known about surface carbohydrates and PMN-epithelial interactions. Here we investigate the role of carbohydrates on PMN-epithelial interactions using PMN and cultured monolayers of the intestinal epithelial cell line T84. Addition of the carbohydrates mannose 6-phosphate (Man-6-P) and glucose 6-phosphate (Glu-6-P), but not fructose 1-phosphate (Fru-1-P) inhibited transmigration by > or = 70%. Likewise, more complex carbohydrates, such as fucoidin and the Man-6-P-rich polysaccharide PPME selectively inhibited PMN transepithelial migration. These carbohydrates were found to be inhibitory in the apical-to-basolateral direction as well as the basolateral-to-apical direction, indicating a lack of polarity. This panel of related carbohydrates, however, was not effective in modulating short-term adhesion of PMN to epithelial monolayers, indicating that carbohydrate ligands may modulate different steps in the transmigration cascade. Finally, addition of functionally inhibitory monoclonal antibodies specific for the selectins (CD62E, CD62L, and CD62P) revealed no observable effect on PMN transmigration. These studies suggest that cell surface carbohydrates may play a role in inflammatory processes of the intestine.

Carbohydrate Metabolism↗

PubMed1995

Complement-mediated loss of endothelium-dependent relaxation of porcine coronary arteries. Role of the terminal membrane attack complex.

Reperfusion of the ischemic myocardium results in the loss of endothelium-dependent relaxation. We have shown recently that the alternate complement pathway is activated immediately on reperfusion of the ischemic porcine myocardium. We hypothesized that complement activation directly attenuates endothelium-dependent relaxation of porcine coronary arteries. Bradykinin (BK) or substance P concentration-dependently relaxed precontracted (U46619, 50 nmol/L) left anterior descending coronary artery (LAD) rings in vitro. Addition of zymosan to human (10%) or porcine (10%) serum for 30 minutes significantly (P < 0.05) increased the EC50 of BK-induced LAD relaxation from 4 +/- 1 to 418 +/- 159 nmol/L (n = 8) and from 9 +/- 3 to 281 +/- 132 nmol/L (n = 7), respectively. Similarly, addition of zymosan to 10% human serum (HS) for 30 minutes increased the EC50 of substance P-induced LAD relaxation from 0.4 +/- 0.1 to 30 +/- 14 nmol/L (n = 9, P < .05). Basal release of nitric oxide was reduced significantly in LAD rings exposed to zymosan-activated HS compared with HS alone. Addition of soluble CR1 (sCR1, 10 nmol/L) to zymosan-activated HS preserved BK-induced relaxation (EC50) of the LAD rings (control, 4 +/- 1 nmol/L; sCR1 + zymosan+serum, 2 +/- 1 nmol/L; n = 6). Zymosan-activated C8-depleted HS (10%) did not attenuate the EC50 of BK-induced coronary artery relaxation (3 +/- 1 to 3 +/- 1 nmol/L, n = 7, P = NS). Zymosan-activated C8-depleted HS plus C8 (6 micrograms/mL) increased the EC50 of BK-induced coronary artery relaxation from 4 +/- 1 to 423 +/- 141 nmol/L (n = 12, P < .05). We have further demonstrated that C5b-9 complexes can be found on the luminal surface of LAD endothelial cells after 5 minutes of exposure to zymosan-activated HS by using C5b-9 reactive monoclonal antibody fluorescent immunohistochemistry and confocal microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Monocyte chemoattractant protein-1 regulates adhesion molecule expression and cytokine production in human monocytes.

Monocytes play a critical role in defending the host against foreign organisms and in regulating the behavior of other cells. Monocytes circulate as nonadherent cells in the blood and migrate as adherent cells through tissues. Adhesion molecules mediate not only cell adhesion, but also migration, phagocytosis, and many other adhesion-dependent functions. Monocyte chemoattractant protein-1 (MCP-1) is thought to be responsible for monocyte recruitment in acute inflammatory conditions and may be an important mediator in chronic inflammation. In this study, immunofluorescence flow cytometry was used to determine whether MCP-1 can regulate the cell surface expression of adhesion molecules, particularly beta-2 and alpha-4 integrins and the leukocyte adhesion molecule-1. We found that MCP-1 induced expression of CD11c (p150,95 alpha-subunit) and CD11b (Mac-1 alpha-subunit), and caused little or no change of CD11a (lymphocyte function-associated Ag-1 alpha-subunit), very late activation Ag-4, or leukocyte adhesion molecule-1. We demonstrated that antibodies to beta-2 and alpha-4 integrins inhibited MCP-1-induced monocyte chemotaxis. We also showed that MCP-1 is capable of inducing IL-1 and IL-6, but not TNF production of monocytes. These results indicate that MCP-1 is not only a chemoattractant but also a novel cytokine with the capacity to regulate several parameters of monocyte function.

Antigens, CD↗

PubMed1992

Interleukin 3: from colony-stimulating factor to pluripotent immunoregulatory cytokine.

IL-3 is best known as a multicolony-stimulating factor, produced by T-cells, mast cells and eosinophils. Based on its broad spectrum of hemopoietic growth factor activity, the role of IL-3 in the homeostasis of leukocytes is apparent, although the precise mechanisms of this process are yet to be determined. The fact that activated T-helper cells are one of the most potent sources of IL-3 suggests an additional role for IL-3 in the regulation of the immune response. Although the presence of IL-3 receptors on monocytes has been demonstrated, the role of IL-3 in regulating macrophage functions was not clear until recently. We have demonstrated a unique spectrum of macrophage activating properties of IL-3, distinct from that of IFN gamma, IL-4 and other CSFs. These novel macrophage activating properties of IL-3 include its capacity to directly induce the expression of Ia antigens and members of the beta 2 integrin family (e.g. CD11a/CD18[LFA-1]), as well as to contribute to the regulation of cytokine production (IL-1, IL-6 and TNF alpha). Moreover, we observed a significant synergy between IL-3 and IFN gamma in the induction of Ia and LFA-1, as well as between IL-3 and LPS in the induction of Ia and macrophage cytokines. Our data suggest that IL-3 may help control the antigen presentation (AP) capacity of macrophage via the regulation of Ia, beta 2 integrins and macrophage cytokines. It is also possible that the differential state of activation of macrophages that we demonstrated following their induction with IL-3, IFN gamma or IL-3+IFN gamma results in the development of functionally distinct AP cells. Further immunoregulatory properties of IL-3 were observed in vivo by Kimoto and colleagues when IL-3 administration led to profound enhancement of the T-cell-dependent immune response, with no changes in the antibody response to T-cell-independent antigens. Thus, in vitro and in vivo data both confer an immunoregulatory role for IL-3 in the development of the immune response, most likely via its effects on the antigen presenting cells (macrophages). This review will summarize evidence documenting a range of immunoregulatory properties of IL-3 and discuss the mechanisms of action of IL-3.

Animals↗

PubMed1990

Aberrant regulation of IL-1 expression in macrophages from young autoimmune-prone mice.

IL-1 is a multifunctional, immunoregulatory polypeptide produced by many cell types. Because activated macrophages are a major source of IL-1 and have also been implicated in the pathogenesis of autoimmune disease, we investigated the regulation of IL-1 expression in several autoimmune-prone strains of mice. Peritoneal macrophages derived from the autoimmune-prone strains MRL/lpr, MRL/+, NZB, and NZB/W F1, as well as NZW, displayed transient expression of IL-1 in contrast to the stable expression characteristic of control normal strains including A. Thy, A/J, B10, B10.A, B10.D2, C57BL/6, BALB/c, and C3H/HeN. The down-regulation of IL-1 by macrophages from the autoimmune-prone mice was not attributable to inherently defective signal transduction because macrophages from both the normal and autoimmune-prone strains displayed substantial initial levels of cell-associated and secreted IL-1. However, during the first 2 to 3 days in culture, macrophages from autoimmune-prone mice became progressively refractory to both induction and maintenance of IL-1, a pattern that correlated with changes in the levels of IL-1 alpha and beta mRNA. The progressive reduction in IL-1 expression by macrophages from these autoimmune-prone strains was not due to a reduction in general metabolism or viability, because expression of cell surface antigens, including MHC class I and II Ag and LFA-1, was comparable to that of control macrophages. Because IL-1 plays a critical role in the homeostasis of a variety of cell lineages, defective expression, and maintenance of IL-1 (and perhaps other cytokines) by macrophages from the autoimmune-prone strains may contribute to the immune dysregulation that develops in these mice. Alternatively, cytokine dysregulation might not contribute directly to disease, but rather reflect a more basic defect related to specific signal transducing or gene regulatory pathways.

Animals↗

PubMed1990

Regulation of macrophage activation by IL-3. II. IL-3 and lipopolysaccharide act synergistically in the regulation of IL-1 expression.

We have previously reported that IL-3, a cytokine produced by both Th1 and Th2 type CD4+ T cells, displays macrophage-activating potential. IL-3, like IFN-gamma, readily induced functions related to Ag presentation (e.g., Ia and lymphocyte function-associated Ag-1 expression). However, in contrast to the response elicited by IFN-gamma, tumor cytotoxicity was not induced by IL-3. In this paper we have evaluated the capacity of IL-3 to regulate IL-1 expression. Our data demonstrate that although IL-3 alone was unable to induce the production of substantial IL-1 bioactivity in peritoneal exudate cells, it contributed synergistically to the induction of IL-1 bioactivity in the presence of suboptimal doses of LPS. It was of interest that IFN-gamma, which can also interact synergistically with LPS, was unable to complement the partial signals provided by IL-3 for the expression of IL-1 bioactivity, suggesting that IL-3 and IFN-gamma may be providing similar stimulatory signals in this respect. Our studies on the mechanism of synergy between IL-3 and LPS indicated that the effect of LPS did not appear to be mediated by the well-characterized LPS-inducible cytokines of macrophage origin (i.e., IL-1, alpha and beta, TNF-alpha, and IL-6). The best characterized function of IL-3 is its multicolony-stimulating activity as a CSF; in this context we also studied granulocyte-macrophage CSF and noted that it behaves similarly to IL-3 in that it can synergistically contribute to IL-1 induction. A similar, but more dramatic induction of IL-1 synthesis in response to IL-3 was demonstrated by the P388.D1 murine macrophage cell line. The kinetics and the molecular mechanism of the response of P388.D1 to IL-3 indicate several unique features of IL-3-induced IL-1 expression: 1) IL-3 itself induced IL-1 mRNA expression, which was unaccompanied by substantial production of bioactivity, either cell-associated or secreted into the culture supernatant; 2) IL-3 synergized with suboptimal doses of LPS to induce not only heightened IL-1 mRNA levels but bioactivity as well; and 3) IL-3, when combined with LPS, altered the kinetics of IL-1 message and bioactive protein production in response to LPS: IL-3 and LPS induced an early release (3 to 7 h poststimulation) of the IL-1 protein as well as a second peak of mRNA and bioactivity (at 12 to 36 h), which was not observed in response to either IL-3 or LPS alone.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

Regulation of macrophage activation by IL-3. I. IL-3 functions as a macrophage-activating factor with unique properties, inducing Ia and lymphocyte function-associated antigen-1 but not cytotoxicity.

Here we report that IL-3 (also referred to as multi-CSF because of its colony-stimulating activity on a variety of hemopoietic cell lineages) can function as a macrophage-activating factor (MAF). IL-3 was able to regulate the expression of class II MHC Ag and the cellular interaction molecule lymphocyte function-associated Ag-1 on the surface of murine peritoneal exudate cells. The kinetics of IL-3-induced Ia expression appeared to be distinct from that induced by either IFN-gamma, IL-4, or granulocyte-macrophage-CSF. IL-3 was also distinguished from these factors by the finding that it did not induce macrophage tumoricidal activity. In addition to its inherent MAF activities, IL-3 also showed a marked synergy with low doses of LPS (0.05 to 0.5 ng/ml) as well as IFN-gamma in Ia induction. When lymphocyte function-associated Ag-1 expression was evaluated, the effects of these stimuli appeared to be only additive. Although LPS has been shown to inhibit IFN-gamma-induced Ia expression, in our experiments this property of LPS is manifest only when present at doses greater than or equal to 50 ng/ml. At lower concentrations, LPS potentiated both IL-3- and IFN-gamma-induced class II MHC Ag expression. Data presented here also suggest that the synergistic interactions between low doses of LPS and IL-3 are not mediated by known LPS-inducible cytokines of macrophage origin, because rIL-1, TNF-alpha, or IL-6 did not enhance the response to IL-3. Because IL-3 can also participate in the regulation of IL-1 expression, it appears that IL-3 can function as a MAF which selectively regulates the accessory cell characteristics required for Ag presentation, as opposed to the cytolytic functions of the macrophage.

Animals↗

PubMed1985

Effect of dialysable leukocyte extract on the mononuclear leukocytes in Hodgkin's disease.

Therapy with dialysable leukocyte extract repeated 6 times, had a beneficial effect on the impaired functions of mononuclear leukocytes in Hodgkin's disease. The decreased phagocytosis and chemotaxis of monocytes increased almost to the values of healthy controls. There was no significant change in the C3b receptor activity of the patients' monocytes but their pathologically increased EA rosette formation showed some correction during dialysable leukocyte extract therapy. The number of T cells bearing histamine and IgG Fc receptors was reduced initially and increased during therapy but this effect was only temporary. The results suggest that the stimulating effect of dialysable leukocyte extract on cellular immunity was due partly to the correction of mononuclear phagocyte functions rather than an effect on lymphocyte subpopulations in Hodgkin's disease. The beneficial effect of transfer factor on mononuclear phagocyte function may affect the rate of tumour progression and reduce the number of severe infections in patients with Hodgkin's disease.

Antigen-Antibody Complex↗

PubMed1980

Monocyte chemotaxis and effect of levamisole in Hodgkin's disease.

Monocyte chemotaxis and its response to levamisole were studied in patients with Hodgkin's disease. Levamisole caused a significant improvement of the deficient monocyte chemotaxis of the patients. By enhancing monocyte functions including chemotaxis, levamisole may contribute to the improvement of cellular immune reactivity, thus increasing the resistance to infections and prolonging the periods of remission.

Chemotaxis, Leukocyte↗

PubMedDate not supplied

Monocyte functions in patients with mixed connective tissue disease.

The authors investigated the number and functions of peripheral blood monocytes in patients with mixed connective tissue disease. Moderate monocytopenia was detected in the active stage of the disease. There was a close correlation between the sensitized sheep red blood cell binding capacity of monocytes and the elevated levels of circulating immune complexes. The yeast phagocytosis of monocytes and the chemotactic activity were normal in patients with mixed connective tissue disease. C3b receptor mediated phagocytosis of monocytes decreased in the active and inactive stages of the disease. This study suggests that the decreased function of C3b receptors of monocytes is related to the pathogenesis of this disease.

Adolescent↗

PubMedDate not supplied

Polymorphonuclear functions in patients with mixed connective tissue disease.

Polymorphonuclear leukocytes (PMNs) from 29 patients with mixed connective tissue disease (MCTD) were studied "in vitro" for their phagocytic and chemotactic function as well as for granulocyte alkaline phosphatase (GAP) activity. Fc-receptor expression detected by EA-rosette formation was comparable to the control. Yeast-phagocytosis, C3b-receptor mediated phagocytosis and chemotaxis of PMNs, however, significantly decreased in MCTD. At the same time, photometric measure of alkaline phosphatase activity indicated a nearly two fold increase in PMNs from patients with MCTD. Although no correlation was found between PMN functions and the activity of the disease, PMN disorders may play a role in pathogenesis of these connective tissue disorders.

Adult↗