Navegando por Palavras-chave "mast cell"
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- ItemSomente MetadadadosDiscriminating between the activities of human cathepsin G and chymase using fluorogenic substrates(Wiley-Blackwell, 2011-08-01) Korkmaz, Brice; Jegot, Gwenhael; Lau, Laurie C.; Thorpe, Michael; Pitois, Elodie; Juliano, Luiz [UNIFESP]; Walls, Andrew F.; Hellman, Lars; Gauthier, Francis; Univ Tours; Southampton Gen Hosp; Uppsala Univ; Universidade Federal de São Paulo (UNIFESP)Cathepsin G (CG) (EC 3.4.21.20) and chymase (EC 3.4.21.39) are two closely-related chymotrypsin-like proteases that are released from cytoplasmic granules of activated mast cells and/or neutrophils. We investigated the potential for their substrate-binding subsites to discriminate between their substrate specificities, aiming to better understand their respective role during the progression of inflammatory diseases. in addition to their preference for large aromatic residues at P1, both preferentially accommodate small hydrophilic residues at the S1' subsite. Despite significant structural differences in the S2' subsite, both prefer an acidic residue at that position. the Ala226/Glu substitution at the bottom of the CG S1 pocket, which allows CG but not chymase to accommodate a Lys residue at P1, is the main structural difference, allowing discrimination between the activities of these two proteases. However, a Lys at P1 is accommodated much less efficiently than a Phe, and the corresponding substrate is cleaved by beta 2-tryptase (EC 3.4.21.59). We optimized a P1 Lys-containing substrate to enhance sensitivity towards CG and prevent cleavage by chymase and beta 2-tryptase. the resulting substrate (ABZ-GIEPKSDPMPEQ-EDDnp) [ where ABZ is O-aminobenzoic acid and EDDnp is N-(2,4-dinitrophenyl)-ethylenediamine] was cleaved by CG but not by chymase and tryptase, with a specificity constant of 190 mM(-1).s(-1). This allows the quantification of active CG in cells or tissue extracts where it may be present together with chymase and tryptase, as we have shown using a HMC-1 cell homogenate and a sputum sample from a patient with severe asthma.
- ItemSomente MetadadadosDoes Preoperative Electrical Stimulation of the Skin Alter the Healing Process?(Elsevier B.V., 2011-04-01) Borba, Graziela Maria Chacon [UNIFESP]; Hochman, Bernardo [UNIFESP]; Liebano, Richard E.; Enokihara, Milvia M. S. S. [UNIFESP]; Ferreira, Lydia Masako [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Univ City São Paulo UNICIDBackground. in vitro studies have demonstrated that electrical current may affect fibroblast proliferation and synthesis of collagen fibers. in humans, the application of electrical current by positioning the positive electrode on skin wounds resulted in thinner hypertrophic scars. the aim of this study was to evaluate the effects of preoperative electrical stimulation on cutaneous wound healing in rats.Materials and Methods. Forty rats were divided into two groups of 20 animals each. in the control group, an incision was made on the back of the animals. in the stimulation group, a preoperative electrical stimulation was applied using a rectangular pulse current at a frequency of 7.7 Hz, and intensity of 8 mA, for 30 min, with the positive electrode placed on the back of the animal, and the negative electrode placed on the abdominal wall. Following, an incision was made on their back. Biopsy was carried out on postoperative day 7 and 14, and histologic analysis was performed.Results. the number of newly formed vessels, fibroblasts, and type III collagen fibers in the stimulation group on postoperative day 7 were greater than those in the control group.Conclusions. Preoperative positive-polarity electrical stimulation positively affects angiogenesis and fibroblast proliferation. (C) 2011 Elsevier Inc. All rights reserved.
- ItemSomente MetadadadosGap junctions between mast cells and fibroblasts in the developing avian eye(Karger, 1995-01-01) Oliani, Sonia Maria [UNIFESP]; Girol, Ana Paula [UNIFESP]; Smith, Ricardo Luiz [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Mast cells are present in the eye of chick embryos from the 14th day onward, displaying metachromatic granules, mainly in the iris anterior surface and pectinate ligament, Ultrastructurally these cells show electron-dense granules and a few thin and short cytoplasmic projections in close contact with fibroblasts. Sometimes these contacts are extensive, with long fibroblast projections partially involving the mast cells. Gap junctions between mast cells and fibroblasts are observed only in the eyes of 16- and 20-day-old embryos. These intercellular specializations are represented by a close apposition of cytoplasmic membranes with an extension up to 300 nm. Gap junctions between mast cells and fibroblasts were not observed previously in vivo or in vitro, although in vitro studies have shown that a number of functionally critical interactions may occur between these cells. Our morphological findings suggest that, in vivo, fibroblasts interact with mast cells and may influence their maturation.
- ItemSomente MetadadadosInflammation-induced modulation of cellular galectin-1 and-3 expression in a model of rat peritonitis(Birkhauser Verlag Ag, 2006-03-01) Gil, C. D.; Cooper, D.; Rosignoli, G.; Perretti, M.; Oliani, S. M.; UNESP; Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP); Queen Mary Sch Med & DentObjective and design: To investigate the effect of galectin-1 (Gal-1) and -3 (Gal-3) on leukocyte migration and analyze the expression of both galectins in inflammatory cells using a model of rat peritonitis.Material or Subjects: Sprague-Dawley rats (n = 4 per group).Treatment: Peritonitis was induced in animals through intraperitoneal injection of carrageenin (1.5 mg/kg) and rat mesenteries were analyzed at different time points (0, 4, 24 and 48h). for pharmacological treatment, rats received intravenous injection of Gal-1 or -3 (3 mu g/kg) followed by carrageenin.Methods: Western blotting and immunoelectron microscopy analysis. Statistical analysis was performed using ANOVA followed by Bonferroni test.Results: Pharmacological treatment with Gal-1, but not Gal-3, inhibited (similar to 50%) leukocyte recruitment into the peritoneal cavity at 4h time-point. in this early phase, immunogold staining of mesenteries showed a diminished Gal-3 expression in degranulated mast cells and Gal-1 in transmigrated neutrophils (similar to 20% reduction compared to intravascular cells). in the later phases (24 and 48 h), leukocyte turnover was associated with augmented Gal-1 expression in neutrophils and macrophages and Gal-3 in mast cells and macrophages.Conclusions: These results point to a balanced expression of cell-associated-Gal-1/Gal-3 and might impact on the development of new therapeutic strategies for inflammatory diseases.
- ItemSomente MetadadadosPolycationic peptides as inhibitors of mast cell serine proteases(Elsevier B.V., 2003-04-01) Lundequist, A.; Juliano, M. A.; Juliano, L.; Pejler, G.; Swedish Univ Agr Sci; Universidade Federal de São Paulo (UNIFESP)When mast cells are activated, e.g. during allergic responses, they secrete the serine proteases chymase and tryptase, which both are complex-bound to heparin proteoglycan in vivo. Previous reports have demonstrated potent pro-inflammatory effects of both tryptase and chymase in different animal models, suggesting that these serine proteases may be relevant targets for therapeutic intervention. Recent investigations have shown that heparin-binding compounds can cause tryptase inhibition and it has been suggested that the inhibitory activity of such compounds is due to interference with the binding of heparin to tryptase. Here we tested various polycationic peptides for their ability to inhibit heparin-free human recombinant betaI-tryptase. We demonstrate powerful direct inhibition of tryptase (IC50 values similar to 1-100 nM) by poly-Arg and poly-Lys of different molecular weights. Poly-Arg and poly-Lys showed predominantely competitive inhibition kinetics, although decreases in the k(cat) values for the chromogenic substrate S-2288 were also observed. Peptides built up from heparin-binding motifs were also inhibitors of tryptase, albeit of lower efficiency than poly-Arg/Lys. Tryptase inhibition was strongly dependent on the size of the polycationic peptides. the various polycationic peptides were also inhibitory for heparin-dependent activities of chymase. the tryptase inhibition caused by the polycationic peptides could be reversed by adding heparin. After heparin-induced rescue of tryptase activity, the major part of the tryptase activity was sensitive to inhibition by bovine pancreatic trypsin inhibitor, whereas tryptase before addition of polycationic peptide was completely resistant. Taken together, our findings indicate that polycationic peptides can be used as powerful agents for combined inhibition of mast cell tryptase and chymase. (C) 2003 Elsevier Science Inc. All rights reserved.