PubMed Health⌕ Search

Biomedical subjects

P Conti

Publications and source records attributed to P Conti.

At least 109 records · Page 6Linked to original sources
PubMed1992

Inhibition of interleukin-1 beta mRNA expression and interleukin-1 alpha and beta secretion by a specific human recombinant interleukin-1 receptor antagonist in human peripheral blood mononuclear cells.

The transcription and translation of interleukin-1 (IL-1) may have a pleiotropic effect on the immune system and inflammatory diseases. Recently it has been reported that human monocytes not only produce IL-1 but also induce, with adherent IgG, the secretion of an IL-1 receptor antagonist (IL-1Ra), which can play an essential in vivo and in vitro role in the regulation of IL-1 activity. Recombinant human (rh) IL-1Ra is structurally similar to IL-1 beta but with no IL-1-like activity, and specifically binds to the IL-1 receptor. To more fully evaluate and clarify the inhibitory effect of rhIL-1 receptor antagonist on IL-1 we have studied the influence of rhIL-1Ra on IL-1 transcription and translation. In this report we show that IL-1 beta mRNA from peripheral blood mononuclear cells (PBMC) is strongly inhibited (66%) when rhIL-1Ra (250 ng/ml) was added to cultured cells activated with lipopolysaccharide (LPS) (100 ng/ml) for 4 hr, determined with the slot blot analysis. The addition of exogenous rhIL-1 beta to the cell culture diminished the inhibitory effect (44%). Moreover, we report that the block of IL-1 mRNA transcription consequently leads to the inhibition of IL-1 alpha and IL-1 beta secretion in human PBMC, as measured by ELISA method. In fact, herein we show that LPS activates human PBMC to secrete IL-1 beta and IL-1 alpha, an effect inhibited, in a dose-dependent fashion by rhIL-1Ra (0.025-250 ng/ml) in an overnight incubation. Since IL-1 is a strong inducer of IL-1 synthesis in vivo and in vitro, in our study we used rh IL-1 alpha to stimulate the secretion of IL-1 beta in human PBMC. This activation, carried out overnight, also provoked the release of IL-1 beta in a dose-dependent manner, which was strongly inhibited by rhIL-1Ra used at different concentrations (0.025-250 ng/ml). The inhibitory effect exerted by IL-1Ra on human PBMC IL-1 mRNA transcription and the down-regulation of secretion of IL-1 beta stimulated by IL-1 alpha, may contribute to therapeutic effects in inflammatory diseases such as rheumatoid arthritis and other autoimmune diseases.(ABSTRACT TRUNCATED AT 400 WORDS)

Cells, Cultured↗
PubMed1991

Human recombinant interleukin-1 receptor antagonist inhibits lymphocyte blastogenesis induced by concanavalin A. Restorative effect of hrIL-1.

Interleukin-1 (IL-1), mainly produced by monocyte-macrophages, is a polypeptide cytokine with pleiotropic biological effects. IL-1 plays an important role in mediating immune response and inflammation. Recently a natural inhibitor to IL-1 has been discovered, interleukin-1 receptor antagonist (IL-1ra), produced by human monocytes cultured on adherent IgG which binds to the IL-1 receptors. In our study we found that the pretreatment of cells with serial dilutions of IL-1ra (250 ng/ml-2.5 pg/ml) inhibits, in a dose-dependent manner, lymphocyte DNA synthesis stimulated with Con A (10 micrograms/ml). IL-1ra did not have any effect on resting peripheral blood mononuclear cells (PBMC). Time course experiments show that IL-1ra at 250 ng/ml has its maximum inhibitory effect on lymphocyte blastogenesis when cells are pretreated 2 h before Con A. No effect was found when hrIL-1ra was added after Con A. Moreover, hrIL-1ra also inhibits the enhancing effects of exogenous hrIL-1 (400, 200, 100 and 50 ng/ml) on lymphocytes stimulated with Con A; while when hrIL-1ra was used on cells treated with only Con A, the inhibition was more pronounced. When PBMC were removed from monocytes, by adherence, the Con A-treated lymphocytes were not influenced by 2 h pretreatment of hrIL-1ra; while a strong inhibition was found when exogenous hrIL-1 was added at different concentrations. In addition, hrIL-1ra also inhibits the enhancing effect of hrIL-2 on lymphocyte DNA synthesis. In another set of experiments PBMC were pretreated with hrIL-1ra (250 ng/ml) for 2 h and then added LPs (10 ng/ml) and IL-1 alpha generation was determined using ELISA. In these experiments IL-1ra completely abolished the generation of IL-1 alpha. These data suggest that hrIL-1ra exhibits a dose-response inhibition of lymphocyte blastogenesis induced by Con A, probably through the down-regulation of IL-1 synthesis necessary as an early signal for T-cell activation and IL-2 production.

Cells, Cultured↗
PubMed1991

Inhibition of leukotriene B4 in neutrophils by lipoxins A4 and B4.

Lipoxins are derived from the oxygenation products of arachidonic acid in human leukocytes. They have exhibited selective biological effects different from those of other eicosanoids. We have examined the effect of lipoxin A4 and B4 (LXA4, LXB4) on the production of leukotriene B4 (LTB4) in human neutrophils. Cultured human polymorphonuclear leukocytes were preincubated with LXA and B and their ability to inhibit LTB4 generation was assessed after incubation with calcium ionophore A23187. We found that the pretreatment of neutrophils with lipoxins inhibit the release of LTB4 by A23187 stimulated PMNs. Our data suggests that LXA4 and B4 can contribute to immunosuppression in an inflammatory state via the inhibition of LTB4 synthesis.

Calcimycin↗
PubMed1991

Reduced mitogen stimulation of DNA synthesis in human lymphocytes by a human recombinant interleukin-1 receptor antagonist.

The monokine interleukin-1 is produced by monocytes/macrophages after antigen/LPS stimulation and is an important early signal for the activation of resting T cells to become antigen specific T cells. However, little is known about the regulation and inhibition of IL-1. Recently, a new monokine has been described, generated by human macrophages, called interleukin-1 receptor antagonist (IL-1ra). This new monokine adheres to IL-1 in solution and blocks IL-1 receptor binding. IL-1ra is a glycoprotein structurally similar to IL-1 beta but having no interleukin-1-like activity. Using as a model mitogen (PHA 20 micrograms/ml)-stimulated lymphocyte DNA synthesis, we found that hrIL-1ra (30 min lymphocyte pretreatment) inhibits [3H]thymidine incorporation in a dose-dependent manner. This effect is most probably due to the inhibition of endogenous IL-1, which is a very important signal for T cell activation. The inhibition was maximum at the highest hrIL-1ra concentration used (250 ng/ml). However, when hrIL-1ra was added 2 h after PHA (20 micrograms/ml), a little, if any, inhibition of lymphocyte proliferation was found. The addition of hrIL-1ra simultaneously to the cell cultures with [3H]thymidine [( 3H]TdR) 6 h before the end of culture incubation did not significantly modify the results compared to the cells treated with PHA alone, indicating no interference of hrIL-1ra on [3H]TdR lymphocyte incorporation. We also found that the antibody anti-IL-1 beta inhibits mitogen stimulated lymphocyte DNA synthesis in dose-dependent concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA↗
PubMed1991

Activation of human natural killer cells by lipopolysaccharide and generation of interleukin-1 alpha, beta, tumour necrosis factor and interleukin-6. Effect of IL-1 receptor antagonist.

The presence in the body of an antigen species or a bacterial lipopolysaccharide (LPS) has a pleiotropic effect on the immune system activating macrophages, lymphocytes and natural killer (NK) cells. Recently it has been reported that human macrophages not only secrete interleukin-1 (IL-1) but also its inhibitor, called IL-1 receptor antagonist (IL-1ra), structurally similar to IL-1 beta, but with no IL-1-like activity and which binds to the IL-1 receptor. In this study we show that LPS stimulates NK cell activity and IL-1ra potentiates the stimulatory effect of human recombinant interleukin-2 (hrIL-2) on NK cell activity. In addition, we found that hrIL-1ra inhibits DNA synthesis in lymphocyte culture stimulated with phytohaemagglutinin (PHA) (20 micrograms/ml), presumably via IL-1 inhibition. We also found that LPS is a potent stimulator of monokines: IL-6, tumour necrosis factor-alpha (TNF-alpha), and IL-1 beta, as determined by radioimmunoassay method, and interferon-gamma (IFN-gamma), IL-2, TNF-alpha and IL-1 alpha, as determined by ELISA method, in peripheral blood mononuclear cells (PBMC). We used PBMC as effector cells since LPS requires the presence of accessory cells to activate lymphocytes and bind to the HLA-DR molecule on accessory cells. The effect of LPS on PBMC cytotoxicity has been compared with an endotoxin-free extract of Escherichia coli, OM-8990, which did not provoke cytokine production nor did it cause enhancement of NK cell activity. We found that human recombinant IL-1ra potentiates the stimulatory effect of IL-2 on NK cell activity, similar to hrIL-1 beta. The potentiation of IL-2 in stimulating NK cell activity by IL-1ra is not yet understood. Since IL-1ra is a part of the IL-1 family, it may work in a similar fashion to IL-1, which also potentiates IL-2 to enhance NK cell activity but has been shown not to be directly important in tumour cell killing. In addition, hrIL-1ra can amplify the effect of IL-2 on NK activity, possibly by inhibiting the cyclo-oxygenase products, which are immunosuppressive and are generated in antigen-stimulated PBMC cultures. The generation of IFN-gamma by PBMC after treatment with LPS strongly suggests that the enhancement of NK cell activity may be indirectly due to IFN production.

Cytotoxicity, Immunologic↗
PubMed1990

Lipoxins A4 and B4 inhibit leukotriene B4 generation from human neutrophil leukocyte suspensions.

Lipoxins A4 and B4 (5,6,15L-trihydroxy-7,9,11,13-eicosatetraenoic and 5D,14,15-trihydroxy-6,8,10,12-eicosatetraenoic acids, respectively) were examined in several biological systems and have proven to have many different activities from those of other eicosanoids. Cultured human polymorphonuclear leukocytes were preincubated with LXA and B and their ability to inhibit leukotriene B4 generation was assessed after incubation with the calcium ionophore A23187. The preincubation time of neutrophils with lipoxin A4 and B4 was 15 min. After that time the cells were incubated for 6 min with A23187 (5 microM) for the release of LTB4. We found that the pretreatment of neutrophils with lipoxins inhibited the release of LTB4 by A23187-stimulated PMNs. Nordihydroguaiaretic acid (NDGA) (10 microM), used as a control, strongly inhibited the generation of LTB4. Since LTB4 has been shown to be a modulator of cellular immunity, our data suggest that lipoxin A4 and B4 can contribute to the immunosuppression via inhibition of LTB4 generation. Moreover, the inhibition of LTB4 by lipoxins in neutrophils could have an important regulatory role in inflammation.

Calcimycin↗
PubMed1990

Leukocyte inhibitory factor activates human neutrophils and macrophages to release leukotriene B4 and thromboxanes.

Recent evidence has proved that cytokines can stimulate the production of 5-lipoxygenase products. Leukotriene B4 (LTB4) is a major mediator of leukocyte activation in acute inflammatory reactions, which produce chemotaxis, lysosomal enzyme release, and cell aggregation. Leukocyte inhibitory factor (LIF) also causes biological responses related to inflammation, i.e., LIF directly induces specific granule secretion by polymorphonuclears (PMNs) and potentiates many formyl-methionyl-leucyl-phenylalanine (FMLPs) mediated responses. Since arachidonic acid products are important mediators of inflammation, we have studied the effects of LIF on the arachidonic acid cascade products LTB4 and thromboxane A2 (TxA2). Resuspended at a final concentration of greater than 95% polymorphonuclear PMNs were isolated and tested with some cytokines on the release of LTB4 and TxA2. Peripheral blood mononuclear cells were isolated and seeded in Petri dishes and incubated for 60 min. Adherent macrophages were used for the cytokine stimulation study. Both types of leukocytes were treated with LIF, interleukin 6 (IL 6), and granulocyte-monocyte colony stimulating factor (GM-CSF) at different concentrations, and test agents A23187 and FMLP. Radioimmunoassay for LTB4 and TxB2 was determined by the resulting supernatants. Treatment of PMNs and macrophages with LIF at different concentrations proved to generate significant increases in LTB4 and TxA2 production. This was compared with IL 6 and GM-CSF, which had no effects. In these experiments, TxA2 generations could not be attributed to platelet contamination of PMN suspensions. The quantity of platelet contamination was not sufficient to influence how much TxB2 was produced. The similarities of LIF to other arachidonate stimulating cytokines suggest a similar mode of action in producing hematologic changes typical of tissue injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcimycin↗
PubMed1990

[Side effects of spinal nerve root radiography. How to reduce them?].

Contrastographic techniques with intrathecal injections (SRG, Myelo-CT) are widely employed in the diagnostic approach to lumbar pathologic conditions. These techniques allow pathologic changes to be demonstrated and the information they yield helps plan the correct surgical approach. However, these invasive examinations are seldom employed for the high incidence of side-effects. The latter are related to various causes, the identification of which can help reduce the side-effects themselves. The authors analyzed a study population of 522 patients subjected to radiculography, using needles of different gauges (18-23 G), and injected non-ionic contrast medium in doses ranging 5-10 ml. The incidence of side-effects was significantly higher in the patients suffering from usual headache (79/237 = 33%), in those under 40 (87/238 = 37%), and in female patients (86/221 = 39%). The incidence of side-effects was lower with fine needles (41/139 = 17%) and contrast medium in doses less than 8 ml (80/337 = 24%). The patients were divided into 4 subgroups according to the different doses of contrast medium administered and to needle gauges: the above parameters exhibited a percentage decrease (21/161 = 14%) with 21-23 G needles and 8 ml of contrast medium. The authors believe it possible to reduce side-effects by using fine needles and smaller doses of contrast medium.

Adolescent↗
PubMed1989

[Vertebral osteochondroma and trauma: a possible etiopathogenic correlation].

Three cases of vertebral osteochondroma are shown. The tumor was localized in the dorsal tract in two cases and in the lumbo-sacral junction in the other one. We found in all the cases, as a common anamnestic point, a clinical history of trauma. The etiopathological hypotheses are discussed and the hypothesis of a possible correlation between trauma and metaplastic osteochondromatosis is presented.

Adult↗
PubMed1988

Restoration of anti-interleukin-1 depressed natural killer activity by human recombinant interferon alpha or gamma, human recombinant interleukin-2 and indomethacin.

The lymphokines interleukin-2 and interferon alpha or gamma are synthesized and secreted by activated mononuclear cells (MC) and play a critical role in the proliferative expansion of T-lymphocyte effector cells during the immune response. The pretreatment of human peripheral blood mononuclear cells (PBMC) with antibody IgG against human interleukin-1 (IL-1) from normal rabbit serum, inhibited their natural killer (NK) activity against both myeloid (K562) and lymphoid (MOLT-4) cell lines. Percent specific lysis of tumor cells decreased by increasing the antibody anti-IL-1 dose in an almost linear fashion. When the effector cells were pretreated with human recombinant interleukin-2, human interferon alpha or gamma and indomethacin alone or in combination, the inhibitory effect of antibody against human IL-1 was almost totally reversed.

Cytotoxicity, Immunologic↗
PubMed1988

Recombinant interleukin 1 and tumor necrosis factor acting in synergy to release thromboxane, 6-KETO-PGF1 alpha and PGE2 by human neutrophils.

The cyclooxygenase pathway promotes formation of an endoperoxide that is the precursor of prostaglandins (PG), thromboxanes (Tx) and prostacyclins (PGI2), all of which have important biologic activities. In this study, we examined the ability of human polymorphonuclears (PMN) to synthesize TRxA2, 6-KETO-PGF1 alpha and PGE2 in response to human recombinant interleukin 1 (IL1) and tumor necrosis factor (TNF) alone and in combination. Blood was obtained from healthy donors and whole blood was centrifuged over Ficoll-Hypaque in 2% dextran for 30 min. PMNs were resuspended in Gey's buffer, exposed to the IL1 and TNF at 300 ng/ml and 0.5 ng/ml concentrations, and incubate for 30 min. at 10(6) cell/ml. Results indicate that IL1 and TNF alone have little or no effect on human neutrophils to synthesize TxA2, 6-KETO-PGF1 alpha and PGE2 production. This effect was completely inhibited by two non-steroidal anti-inflammatory drugs (i.e. indomethacin and proglumetacin).

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Lipoxin A augments release of thromboxane from human polymorphonuclear leukocyte suspensions.

Lipoxin A (LXA) is a novel eicosanoid, generated by the interactions of lipoxygenases, which has a variety of biological actions. When added to human polymorphonuclear leukocytes, LXA stimulated thromboxane formation which was monitored as TxB2 by radioimmunoassay. The compound augmented the formation of TxA2 stimulated by the ionophore of divalent cations (A23187). Formation of thromboxane was inhibited by two non-steroidal anti-inflammatory drugs (i.e. indomethacin and proglumetacin). Results of the present study indicate that LXA can provoke the release and transformation of endogenous arachidonic acid to thromboxane. Moreover, they suggest a relationship between lipoxin A and the formation of cyclooxygenase pathway products.

Calcimycin↗