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Biomedical subjects

L Biancone

Publications and source records attributed to L Biancone.

At least 91 records · Page 5Linked to original sources
PubMed1993

Spontaneous cytotoxicity of intestinal intraepithelial lymphocytes: clues to the mechanism.

Human intestinal intraepithelial lymphocytes (IEL) demonstrate target cell-restricted spontaneous cytotoxic (SC) activity that is due to CD2+CD3+CD8+CD16-CD56- effector cells; they kill epithelial cell (EC) tumours (such as DLD-1 colon cancer cells), but not natural killer (NK)-sensitive K-562 cells. The present study shows that the measured levels of SC activities by IEL correlated with those of autologous lamina propria lymphocytes (LPL), but not with those of peripheral blood lymphocytes (PBL). Also, the susceptibilities of DLD-1 cell clones to lysis by IEL and PBL effector cells did not correlate, suggesting different mechanisms of lysis. Antibody blocking experiments showed that the main surface molecules involved in lysis depended on the effector cell type: alpha E beta 7 (HML-1) on IEL and CD16 on PBL. No antibody-dependent cell-mediated cytotoxicity (ADCC) was demonstrated by IEL, even after stimulation with interferon-gamma (IFN-gamma). Few IEL expressed Fc receptors for IgG. This study describes further differences between the SC activities of IEL and PBL.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1993

Ulcerative colitis serum recognizes the M(r) 40K protein on colonic adenocarcinoma cells for antibody-dependent cellular cytotoxicity.

Antibodies in ulcerative colitis (UC) serum promote antibody-dependent cellular cytotoxicity (ADCC) against colon cancer cells. The target molecules on the cells recognized by the antibody are unknown. This study examines the role of the M(r) 40K colon epithelial protein in this process. Serum from 29 UC patients, but not from 19 patients with Crohn's disease, significantly (p < 0.001) induced more cytotoxicity than did normal serum against DLD-1 colon cancer cells which are known to express the M(r) 40K protein. Peripheral blood lymphocytes but not polymorphonuclear leukocytes showed ADCC. Anti-M(r) 40K monoclonal antibodies significantly (p < 0.001) inhibited the UC-serum-induced ADCC, but not the spontaneous cytotoxicity. These results suggest the involvement of the M(r) 40K protein in ADCC induced by UC serum.

Adenocarcinoma↗
PubMed1993

Role of the membrane attack complex of complement in lung injury mediated by antibodies to endothelium.

The potential pathogenic role of the membrane attack complex (MAC) of the complement system was investigated in two models of lung injury mediated by antibodies to angiotensin-converting enzyme (ACE), an endothelial cell enzyme. In the first model, acute and fatal lung edema was induced in rabbits by intravenous administration of divalent anti-ACE antibodies. These animals died acutely. C6-deficient rabbits tolerated anti-ACE antibodies without apparent ill effects. On the other hand, C6-deficient rabbits reconstituted with C6 and then receiving anti-ACE antibodies developed acute pulmonary edema and died. These results indicate that the MAC is required for the pathogenesis of this lung injury. In the second model, intravenous administration of monovalent anti-ACE Fab fragments over 4 consecutive days induced fatal interstitial pneumonitis in normal rabbits. For C6-deficient rabbits there was a reduced inflammatory response, and no animals died, implicating a mediator function for the MAC in this model as well. These results demonstrate that MAC is an important mediator of acute pulmonary edema induced by divalent antibodies to an endothelial antigen. Moreover, the complement system was also, to some extent, involved in the recruitment of inflammatory cells leading to the development of interstitial pneumonitis in the experimental lung injury induced by monovalent anti-ACE Fab fragments that 'per se' do not activate complement.

Acute Disease↗
PubMed1993

Detection of platelet-activating factor in plasma of patients with streptococcal nephritis.

The purpose of this study was to evaluate whether platelet-activating factor (PAF) is released in the plasma of patients with acute poststreptococcal glomerulonephritis, because previous studies have shown an involvement of platelets in the active phase of this disease. The results of this study indicate that PAF bioactive material is released in significant amounts in the plasma of 49 out of 50 patients with acute poststreptococcal glomerulonephritis. The observed release of PAF was not a direct consequence of the bacterial infection, because it was minimal or absent in patients with streptococcal infection without glomerular involvement. PAF bioactive material extracted and purified from the plasma of patients was shown to be chemically and biologically identical to the synthetic C-16 PAF (1-O-hexadecyl-2-acetyl-sn-glyceryl 3-phosphorylcholine).

Acute Disease↗
PubMed1993

Lansoprazole and Helicobacter pylori infection.

Helicobacter pylori-associated gastritis is present in virtually all patients with duodenal ulcer (DU). Eradication of H pylori is associated with a highly significant decline in the recurrence rates of DU, indicating that treatments aimed at eradicating H pylori are mandatory in these patients. The novel proton pump inhibitor lansoprazole exhibits a potent antiulcer effect and, in vitro, a direct antibacterial effect against H pylori. Conflicting data have been reported on the question of whether lansoprazole is bactericidal against H pylori in vivo when administered alone. The aim of this double-blind trial was to address this issue further by comparing the effects of two different 4-week regimens (lansoprazole alone or in combination with amoxicillin) on H pylori infection in patients with DU. Patients were assessed before and after the 4-week treatment and 3 months after stopping the study medication. The ulcer healing rates at 4 weeks were similar for the two treatments while there was a trend for higher recurrence rates at 4 months in patients receiving lansoprazole alone. The frequency of high-grade H pylori infection was significantly lower in the lansoprazole and amoxicillin group both at 4 weeks (84% clearing) and 4 months. After 4 weeks of treatment there were no patients with residual H pylori-positive active antral gastritis in the lansoprazole and amoxicillin group compared with 25% in the lansoprazole alone group. Neither treatment significantly affected the IgG antibody response to H pylori either at the circulatory or the mucosal level. In contrast, the mucosal H pylori-specific IgA response was significantly enhanced after 4 weeks and more markedly after treatment with lansoprazole.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1993

Role of platelet activating factor in hemodialysis.

A complex array of inflammatory mediators are generated as a consequence of blood contact with hemodialysis (HD) membranes. Beside complement activation, other mediators are involved in cell activation, and are thought possibly to be responsible for early and long-term multiple changes in immunity infection, hypercatabolism, beta 2-microglobulin generation and hemostatic mechanisms. Previous studies from our laboratories have established platelet activating factor (PAF) as one of the mediators generated by complement-dependent or independent mechanisms of cell interaction with hemodialysis membranes. Recent studies on the production of PAF from endotoxin-primed polymorphonuclear neutrophils in a closed miniaturized circuit, and on the effect of PAF in mediating endotoxin- and cytokine-induced leukocyte adherence to HD membranes, highlight so far undescribed new roles of this mediator in biocompatibility.

Blood Physiological Phenomena↗
PubMed1993

Effect of cytokines on the cytoskeleton of resident glomerular cells.

Resident glomerular cells have complex cytoskeletal organizations relevant to maintaining functional and structural integrity. The ability of cells to change shape, develop coordinate directed movements, replicate and interact with contiguous cells or extracellular matrix depends on cytoskeletal functions. Several cytokines directly or indirectly change cytoskeletal organization. Cytokines may alter cytoskeletal organization in cultured glomerular epithelial and mesangial cells and vascular endothelial cells mainly by mechanisms involving production of secondary mediators, such as PAF and leukotrienes that stimulate cell contraction, or PGE2 and PGI2 that stimulate cell relaxation. Consequent assembly and disassembly of microfilaments leads to functional responses of cells that may account for the physiopathological changes induced by cytokines in vivo.

Animals↗
PubMed1992

Salmonella typhimurium porins stimulate platelet-activating factor synthesis by human polymorphonuclear neutrophils.

Porins, a family of hydrophobic proteins located in the outer membrane of cell-wall of Gram-negative bacteria, were shown to stimulate the synthesis and release of platelet-activating factor (PAF), a 1-O-alkyl-2-acetyl-sn-glycerol-3-phosphorylcholine mediator of inflammation and endotoxic shock produced by polymorphonuclear neutrophils. PAF synthesis was independent either from contamination by LPS or generation of TNF. Experiments with labeled precursors demonstrated that PAF was synthesized via the remodeling pathway that involves acetylation of 1-O-alkyl-sn-glyceryl-3-phosphorylcholine generated from 1-O-alkyl-2-acyl-sn-glyceryl-3-phosphorylcholine by phospholipase A2 (PLA2) activity. Porins, indeed, induced a sustained PLA2-dependent mobilization of [14C]arachidonic acid that was inhibited by p-bromodiphenacylbromide. p-Bromodiphenacylbromide, an inhibitor of PLA2, also blocked PAF synthesis by preventing the mobilization of 2-lyso-PAF, the substrate for PAF-specific acetyltransferase. The addition of 2-lyso-PAF restored PAF synthesis. The activity of acetyl CoA:2-lyso-PAF acetyltransferase was transiently increased in porin-stimulated PMN and the [3H]acetyl group was incorporated in the synthetized PAF after cell preincubation with [3H]acetyl CoA. The activation of PAF synthesis by porins as well as its release were dependent on extracellular Ca2+. Porins by forming trans-membrane channels determined a sustained influx of 45Ca2+ into the cytosol. As shown by inhibitors of Ca(2+)-calmodulin complexes, calmodulin mediated the Ca(2+)-dependent activation of enzymes involved in PAF synthesis.

Arachidonic Acid↗
PubMed1992

Porins and lipopolysaccharide stimulate platelet activating factor synthesis by human mesangial cells.

Porins, a family of hydrophobic proteins located in the outer membrane of the cell wall of gram-negative bacteria and lipopolysaccharide (LPS), were shown to stimulate the synthesis of platelet activating factor (PAF), a phospholipid mediator of inflammation and endotoxic shock, by cultured human glomerular mesangial cells (MC). The synthesis of PAF induced by porins was rapid (peak at 20 min) and independent either from contamination by LPS or from generation of an endotoxin-induced cytokine such as tumor necrosis factor (TNF) since it was not prevented by cycloheximide, an inhibitor of protein synthesis or anti-TNF blocking antibodies. LPS also stimulated PAF synthesis by MC. However, the kinetic of PAF synthesis induced by LPS was biphasic with an early and transient peak at 10 minutes and a second and sustained peak at three to six hours. This second peak required an intact protein synthesis and was prevented by anti-TNF antibodies, suggesting the dependency on LPS-induced synthesis of TNF. Experiments with labeled precursors demonstrated that in MC, either after stimulation with porins or LPS, PAF was synthesized via the remodeling pathway that involves acetylation of 1-0-alkyl-sn-glyceryl-3-phosphorylcholine (2-lyso-PAF) generated from 1-0-alkyl-2-acyl-sn-glyceryl-3-phosphorylcholine by phospholipase A2 (PLA2) activity. Porins and LPS, indeed, induced PLA2-dependent mobilization of [14C]-arachidonic acid that was inhibited by p-bromodiphenacylbromide (PBDB). PBDB, an inhibitor of PLA2, also blocked PAF synthesis by preventing the mobilization of 2-lyso-PAF, the substrate for PAF-specific acetyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Outer Membrane Proteins↗
PubMed1992

Production of tumor necrosis factor-alpha in patients on hemodiafiltration.

The systemic production of tumor necrosis factor (TNF)-alpha was evaluated in uremic patients before and after hemodiafiltration (HDF) and paired filtration dialysis (PFD) and in the interdialytic period. Both HDF and PFD were performed using polysulfone dialyzers with either standard or ultrapure dialysis fluid. TNF-alpha was quantitated by using a specific biological assay based on its cytotoxic effect on a TNF-sensitive human melanoma cell line SK-MEL-109. Postdialytic mean plasma TNF-alpha levels decreased, albeit not significantly, in regard to predialytic values. These results differ from those obtained in patients on HDF using other high-permeability membranes such as polymethylmethacrylate and polyacrylonitrile (AN 69) as recently described by us. Of interest, the adoption of ultrapure dialysis fluid resulted in a marked reduction in the interdialytic production of TNF-alpha. These results suggest that the enhanced production of TNF-alpha in patients dialyzed with high-permeability membranes is mainly dependent upon the bacteriological purity of dialysis fluid.

Adult↗
PubMed1992

Platelet-activating factor biosynthesis by cultured mesangial cells is modulated by proteinase inhibitors.

Rat mesangial cells stimulated with calcium ionophore A23187 and phagocytosis were shown to produce platelet-activating factor (PAF), a mediator of inflammation and endotoxic shock. In the study presented here, the cultured human mesangial but not epithelial cells synthetized PAF not only in response to calcium ionophore A23187 and phagocytosis of immunoglobulin G-coated latex beads, but also after stimulation with cytokines such as tumor necrosis factor-alpha and interleukin-1 beta. PAF synthetized after stimulation with A23187 and to a lesser extent with phagocytosis was partially released. In contrast, PAF synthesized by stimulation with tumor necrosis factor-alpha and interleukin-1 beta remained cell associated. Experiments with labeled precursors demonstrated that PAF was synthetized via the remodeling pathway that involves the activation of phospholipase A2 and of an acetyl-coenzymeA:2-lyso-PAF acetyltransferase. Synthetic inhibitors of serine proteases as well as plasma alpha 1-proteinase inhibitor inhibited the activation of phospholipase A2 detected as release of (14C) arachidonic acid and the activation of acetyl-CoA:2-lyso-PAF acetyltransferase at concentrations 100-fold lower than those present in plasma. This raises the question about the ability of mesangial cells to synthetize PAF in vivo. However, the inhibitory effect of plasma alpha 1-proteinase inhibitor may be abrogated by oxidative inactivation due to a concomitant stimulation of mesangial cell respiratory burst or in zones of close contact among cells or matrix, which have been shown to exclude antiproteinases.

Acetyltransferases↗
PubMed1991

Serum immunomodulatory factors in gastrointestinal diseases. A 30-50-kD serum fraction in Crohn's disease capable of modulating lymphocyte activation.

We tested the hypothesis that serum factors present in Crohn's disease interfere with the process of lymphocyte activation. The mitogen-induced proliferation and the expression of early activation antigens by normal lymphocytes cultured in the presence of either Crohn's disease sera or sera from different controls were evaluated. The mitogen-induced proliferation was significantly impaired in the presence of Crohn's disease sera. These sera markedly inhibited the mitogen-induced interleukin-2 receptor (IL-2R) expression (48% inhibition), while the effect of sera on the expression of the transferrin receptor and the 4F2 antigen was much less pronounced. Diafiltration experiments showed that the inhibitory effect was confined to a 30-50-kD serum fraction. Such a serum property was not related to the patients' disease activity and disappeared after surgical removal of the affected bowel. The capability of inhibiting the mitogen-induced IL-2R expression was not restricted to Crohn's disease and was observed with sera from other inflammatory and neoplastic gastrointestinal disorders. This study indicates that a marked inhibition of the IL-2R is a mechanism underlying the immunosuppressive property of the serum in Crohn's disease and in other gastrointestinal conditions.

Adult↗
PubMed1991

The presence in experimental animals of a colon specific Mr 40,000 protein(s) with relevance to ulcerative colitis.

In patients with ulcerative colitis a colon tissue bound IgG and serum antibodies against an Mr 40,000 colonic protein(s) has been identified. Using an anti-Mr 40,000 protein monoclonal antibody, 7E12H12, by an immunocytochemical method, the protein was localised in human tissue exclusively to colonic epithelial cells. In this study the presence of the Mr 40,000 protein was assessed in experimental animals by the direct and inhibition enzyme linked immunosorbent assays (ELISAs) using the anti-Mr 40,000 protein monoclonal antibody, 7E12H12 (IgM isotype). In addition, a total of 129 specimens including colon, small intestine, gall bladder, biliary tract, and kidney from nine strains of rats and mice, and from human tissue were studied by the immunocytochemical method using 7E12H12. All colon specimens from both humans and animals reacted with 7E12H12 in the immunocytochemical and ELISA assays. None of the non-colonic organs reacted with 7E12H12. While in human colon 7E12H12 recognised the absorptive epithelial cells, in all the animals it recognised mainly the colonic goblet cells. Extracts of animal colon but not of small intestine inhibited the binding of 7E12H12 to the human colon extract. This study shows the presence of an organ specific Mr 40,000 colonic epithelial protein(s) in humans and experimental animals. A differing cellular localisation of the Mr 40,000 protein(s) in human v animal tissue was also shown. Further characterisation of the Mr 40,000 protein(s) may provide important clues regarding the autoimmune mechanisms in ulcerative colitis.

Animals↗
PubMed1987

Peripheral and intestinal lymphocyte activation after in vitro exposure to cow's milk antigens in normal subjects and in patients with Crohn's disease.

We studied in Crohn's disease and controls the in vitro activation of either peripheral (PBMNC) or intestinal (LPMNC) mononuclear cells in response to the cow's milk antigen beta-lactoglobulin (Blg). The activation of mononuclear cells was investigated by analyzing the kinetics of the transferrin receptor (T9 antigen) and interleukin 2 receptor (Tac antigen) expression. In both controls and Crohn's disease patients Blg (1 microgram/ml) induced a significant (P less than 0.01) increase of T9 and Tac expression by both PBMNC and LPMNC cultured for 3 days. After Blg exposure the counts of T9- and Tac-bearing cells were significantly (P less than 0.05) higher in PBMNC cultures from healthy controls than in those from patients with Crohn's disease. In both groups peripheral T-enriched cell suspensions did not express T9 and Tac when stimulated with Blg but were restored to express either antigen by the addition of 10% autologous adherent cells. In LPMNC cultures from patients with Crohn's disease the Tac expression after 3 days of Blg stimulation was significantly (P less than 0.05) higher than in the autologous PBMNC. Data from this study indicate that in both controls and patients with Crohn's disease lymphocytes sensitized to Blg occur in the circulation as well as in the gut lamina propria. Our data also suggest that in Crohn's disease an increased proportion of lymphocytes sensitized to Blg are recruited from the circulation into the site of the intestinal lesion.

Adult↗
PubMed1987

Activation of peripheral blood and intestinal lamina propria lymphocytes in Crohn's disease. In vivo state of activation and in vitro response to stimulation as defined by the expression of early activation antigens.

In the present study the state of activation of either peripheral blood and intestinal lamina propria mononuclear cells in Crohn's disease was defined by investigating the expression of early activation antigens (namely the 4F2 antigen, the transferrin receptor and the interleukin-2 receptor). The expression of 4F2 and T9 antigens was greatly increased--in the peripheral blood and in the intestinal lamina propria whereas the proportion of interleukin-2 receptor bearing cells was much less pronounced. The counts of early activation antigens bearing cells in the lamina propria were quite comparable with those of the autologous peripheral cells. In the peripheral blood counts of 4F2 and T9 positive cells were very high in patients with active Crohn's disease but patients with quiescent disease also had a significantly raised proportion of 4F2 and T9 bearing cells. Only in those patients with no evidence of macroscopic disease (namely those resected without recurrence) the counts of early activation antigens bearing cells were within the normal range. The in vitro mitogen induced expression of early activation antigens on either peripheral and intestinal mononuclear cells of patients with Crohn's disease proved to be both quantitatively and qualitatively similar to that of the controls showing the full expression of 4F2, transferrin receptor, and interleukin-2 receptor. While demonstrating that in Crohn's disease there was no intrinsic defect of generation and expression of growth factors receptors by peripheral and intestinal lymphocytes, these results showed that there was a divergence in the expression of early activation antigens in vivo and in vitro. This would indicate that in Crohn's disease there is an in vivo increased population of preactivated rather than fully activated lymphocytes consisting of 4F2 and T9 bearing cells. The high proportion of these cells in the peripheral blood and in the intestine suggests that a chronic immune activation is present in these patients outside as well as within the affected bowel.

Adult↗
PubMed1987

HLA-DR antigens on colonic epithelial cells in inflammatory bowel disease: I. Relation to the state of activation of lamina propria lymphocytes and to the epithelial expression of other surface markers.

The colonic epithelial expression of HLA-DR molecules and of other markers of cell membrane perturbation was investigated by immunofluorescence in biopsy specimens from patients with ulcerative colitis and Crohn's disease. It was found that in virtually all specimens from either groups showing active inflammation there was a diffuse epithelial expression of HLA-DR molecules. There was no relation between the grading of active inflammation and the epithelial expression of HLA-DR antigens. The epithelium of virtually all specimens from the macro and microscopically uninvolved areas of patients with active colitis and from patients with histologically quiescent colitis showed no detectable expression of HLA-DR molecules. The counts of isolated lamina propria lymphocytes expressing the transferrin receptor and the interleukin 2 receptor were higher in specimens with HLA-DR+ epithelium than in those with a HLA-DR- epithelium. Twenty-nine of the 35 (83%) HLA-DR positive specimens proved to express the 4F2 antigen on their epithelium and 19 (54%) were positive for the transferrin receptor. All sections positive for either the 4F2 antigen or the transferrin receptor were also HLA-DR positive while all HLA-DR negative sections were also negative for either of the two other markers. Data in this study suggest that in active IBD the epithelial participation in active inflammation is associated with a sequence of cell membrane rearrangements, and that the expression of HLA-DR molecules is a part of this sequence.

Antigens, Surface↗
PubMed1985

T cell differentiation antigens expressed by peripheral blood lymphocytes in Crohn's disease.

The aim of the present study was to investigate whether an imbalance of peripheral blood immunoregulatory T cells is a feature of Crohn's disease. The cluster of differentiation antigens 3,4 and 8 were investigated and the relative prevalence of PBL expressing each antigen was defined using a panel of three monoclonal antibodies (OKT3, OTK4 and OKT8). A significant decrease in the OKT3 and OKT4 positive cells was found in CD patients as compared with healthy controls. No significant difference was observed between patients and controls in the proportion of T8 positive cells and in the T4/T8 ratio. While confirming a significant decrease of circulating total resting T cells in patient with CD, the results of this study indicate that the disease is not primarily related to an imbalance of the proportion of the T cells subsets.

Adult↗