Differences in nasal cellular infiltrates between allergic children and age-matched controls.
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Little is known about the cellular infiltrates in the nasal mucosa of children. This study was set up to compare the nasal cellular infiltrates in biopsy specimens from allergic children and controls. Atopic children were distinguished from controls on the basis of symptoms of allergic rhinitis and/or asthma, total serum immunoglobulin (Ig)E, family history and specific serum IgE to food and aeroallergens. Fifteen allergic patients (median age 4.3 yrs) and 15 age-matched nonallergic control subjects were evaluated. The number of cells positive for CD1a, CD4, CD8, CD19, CD68, chymase, tryptase, IgE and major basic protein was determined in the mucosa of the inferior turbinate. A significantly higher number of IgE-positive cells and mast cells was found in the epithelia of the allergic group. In the lamina propria, higher numbers of IgE-positive cells and eosinophils were found. Langerhans' cells positive for IgE were only seen in allergic children with specific serum IgE against aeroallergens. These children also had a higher number of IgE-positive mast cells compared to controls and atopic children without specific serum IgE. These results show that the nasal cellular infiltrates of allergic children differ from nonallergic control subjects. Prior to the detection of specific serum immunoglobulin E, cellular changes can be found in the nasal mucosa of atopic children. (+info)
Effects of substance P on human colonic mucosa in vitro.
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Previous studies indicated that the peptide substance P (SP) causes Cl--dependent secretion in animal colonic mucosa. We investigated the effects of SP in human colonic mucosa mounted in Ussing chamber. Drugs for pharmacological characterization of SP-induced responses were applied 30 min before SP. Serosal, but not luminal, administration of SP (10(-8) to 10(-6) M) induced a rapid, monophasic concentration and Cl--dependent, bumetanide-sensitive short-circuit current (Isc) increase, which was inhibited by the SP neurokinin 1 (NK1)-receptor antagonist CP-96345, the neuronal blocker TTX, the mast cell stabilizer lodoxamide, the histamine 1-receptor antagonist pyrilamine, and the PG synthesis inhibitor indomethacin. SP caused TTX- and lodoxamide-sensitive histamine release from colonic mucosa. Two-photon microscopy revealed NK1 (SP)-receptor immunoreactivity on nerve cells. The tyrosine kinase inhibitor genistein concentration dependently blocked SP-induced Isc increase without impairing forskolin- and carbachol-mediated Isc increase. We conclude that SP stimulates Cl--dependent secretion in human colon by a pathway(s) involving mucosal nerves, mast cells, and the mast cell product histamine. Our results also indicate that tyrosine kinases may be involved in this SP-induced response. (+info)
Inflammatory mast cells up-regulate angiogenesis during squamous epithelial carcinogenesis.
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Expression of HPV16 early region genes in basal keratinocytes of transgenic mice elicits a multistage pathway to squamous carcinoma. We report that infiltration by mast cells and activation of the matrix metalloproteinase MMP-9/gelatinase B coincides with the angiogenic switch in premalignant lesions. Mast cells infiltrate hyperplasias, dysplasias, and invasive fronts of carcinomas, but not the core of solid tumors, where they degranulate in close apposition to capillaries and epithelial basement membranes, releasing mast-cell-specific serine proteases MCP-4 (chymase) and MCP-6 (tryptase). MCP-6 is shown to be a mitogen for dermal fibroblasts that proliferate in the reactive stroma, whereas MCP-4 can activate progelatinase B and induce hyperplastic skin to become angiogenic in an in vitro bioassay. Notably, premalignant angiogenesis is abated in a mast-cell-deficient (KITW/KITWWv) HPV16 transgenic mouse. The data indicate that neoplastic progression in this model involves exploitation of an inflammatory response to tissue abnormality. Thus, regulation of angiogenesis during squamous carcinogenesis is biphasic: In hyperplasias, dysplasias, and invading cancer fronts, inflammatory mast cells are conscripted to reorganize stromal architecture and hyperactivate angiogenesis; within the cancer core, upregulation of angiogenesis factors in tumor cells apparently renders them self-sufficient at sustaining neovascularization. (+info)
Leukocytes infiltrate the myometrium during human parturition: further evidence that labour is an inflammatory process.
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Inflammatory mediators in the cervix, placenta and fetal membranes play a crucial role in human parturition. The aim of this study was to determine whether the upper and lower segments of the myometrium are infiltrated by inflammatory cells during pregnancy and parturition. Myometrial biopsies were obtained from non-pregnant women, and pregnant women at term before and after the onset of spontaneous labour. Subpopulations of inflammatory cells were identified using immunocytochemistry. The intercellular adhesion molecules, 1 and 2, platelet endothelial cell adhesion molecule, vascular cell adhesion molecule and E-selectin were immunolocalized to investigate their involvement in leukocyte accumulation. Histological analysis demonstrated that inflammatory cells, predominantly neutrophils and macrophages, infiltrate human myometrium during spontaneous labour at term. The infiltrate is predominant in the lower uterine segment but is also present in the upper segment. Increased expression of E-selectin was found on the vascular endothelium of biopsies obtained during labour, suggesting a role for this molecule in the accumulation of leukocytes. These results suggest that inflammatory cell infiltration is part of the physiological mechanisms that occur in the myometrium during parturition. Further understanding of this process may suggest new strategies aimed at preventing preterm delivery. (+info)
SLP-76 deficiency impairs signaling via the high-affinity IgE receptor in mast cells.
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SLP-76 is an adapter protein expressed in T cells and myeloid cells that is a substrate for ZAP-70 and Syk. SLP-76-deficient mice exhibit a profound block in T-cell development. We found that although SLP-76 is expressed in mouse mast cells, SLP-76(-/-) mice have normal numbers of mast cells in their skin and bronchi. SLP-76(-/-) mice are resistant to IgE-mediated passive anaphylaxis. SLP-76(-/-) mice sensitized with IgE anti-dinitrophenyl (DNP) and then challenged with DNP-HSA developed only mild and transient tachycardia, failed to increase their plasma histamine level, and all survived the antigen challenge. Bone marrow-derived mast cells (BMMCs) from SLP76(-/-) mice failed to release beta-hexosaminidase and to secrete IL-6 after FcepsilonRI cross-linking. Tyrosine phosphorylation of phospholipase C-gamma1 (but not of Syk) and calcium mobilization in response to IgE cross-linking were reduced in SLP-76-deficient BMMCs. These results suggest that SLP-76 plays an important role in FcepsilonRI-mediated signaling in mast cells. (+info)
Immunohistochemical localisation of the matrix metalloproteinases MMP-3 and MMP-9 within the airways in asthma.
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BACKGROUND: The matrix metalloproteinase (MMP) enzymes MMP-3 and MMP-9 have relevance to the chronic structural airway changes in asthma. These proteinases can be generated by structural and inflammatory cells, and have the ability to degrade proteoglycans and thus potentially enhance airway fibrosis and smooth muscle proliferation through their ability to release and activate latent matrix bound growth factors. METHODS: Immunostaining for MMP-3 and MMP-9 as well as for mast cells, eosinophils, and neutrophils was undertaken in acetone fixed and glycolmethacrylate embedded endobronchial biopsy specimens obtained by fibreoptic bronchoscopy under local anaesthesia. The findings from 17 asthmatic subjects (nine with mild to moderate non-steroid treated asthma and eight with chronic persistent steroid-dependent asthma) were compared with those from eight healthy controls. The cell associated MMP immunoreactivity was co-localised to mast cells, eosinophils, or neutrophils and represented as cells/mm2, based on the area of the biopsy specimen. Extracellular matrix immunoreactivity was assessed by an image analysis system and visually with ranking and the two approaches were compared. RESULTS: The biopsy specimens from asthmatic subjects contained significantly more eosinophils (p<0. 001) than those from the non-asthmatic subjects. Both MMP-9 and MMP-3 immunoreactivity could be identified in endobronchial biopsy specimens. Gelatinase B (MMP-9) immunoreactivity was prominent within the extracellular matrix as well as exhibiting distinct cell immunoreactivity which predominantly co-localised to neutrophils. Stromelysin (MMP-3) was co-localised to mast cells, eosinophils, and neutrophils as well as being present in the epithelium, the lamina reticularis and, to a lesser extent, the extracellular matrix. There was no significant difference in the extent of matrix immunoreactivity for either MMP-3 or MMP-9 between healthy controls or subjects with mild or severe asthma. CONCLUSION: Although immunostaining cannot distinguish between active and inactive forms of MMPs, the presence of MMP-3 and MMP-9 within endobronchial biopsy specimens, the co-localisation to inflammatory cells of relevance to asthma (mast cells and eosinophils), and the identification of matrix binding, indicative of MMP-matrix interactions, points to the potential for disease related changes in MMP release that influence airway remodelling in asthma. (+info)
Suppressive effect of distinct bradykinin B2 receptor antagonist on allergen-evoked exudation and leukocyte infiltration in sensitized rats.
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1. Bradykinin is suggested to play a role in the pathophysiology of several acute and chronic diseases, including allergic disorders such as asthma. In the present study, we have investigated the importance of bradykinin in mediating allergic inflammation in rats. 2. To this end we have tested the effects of the B2 receptor antagonists Hoe 140, FR173657 or FR172357 on the pleural inflammatory response triggered by intrapleural (i.pl.) injection of allergen (ovalbumin, 12 microg cavity(-1)) in 14 day-actively sensitized Wistar rats. Analysis of the pleural fluid effluent revealed a sequence of mast cell-dependent inflammatory events, including early protein exudation and neutrophilia and late pleural eosinophil influx. 3. Local treatment with Hoe 140 (0.1 and 1 microg cavity(-1)), FR173657 (1 and 10 microg cavity(-1)) or FR172357 (1 and 10 microg cavity(-1)) inhibited dose-dependently allergen-induced mast cell activation with impairment of pleural plasma leakage, neutrophil accumulation and late eosinophil influx. 4. Moreover, the B2 receptor antagonists also dose-dependently inhibited the allergic like inflammatory pleurisy triggered by bradykinin (50 microg cavity(-1)), which is characterized by acute mast cell degranulation, protein leakage and pleural eosinophil infiltration. 5. Taken together, our findings provide substantial evidence to suggest that bradykinin acting on its B2 receptors play a critical role in mediating allergic mast cell-dependent inflammation in rats, and suggest that B2 receptor antagonists may be useful therapeutically to control allergic dysfunction. (+info)
Human tryptases alpha and beta/II are functionally distinct due, in part, to a single amino acid difference in one of the surface loops that forms the substrate-binding cleft.
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Tryptases alpha and beta/II were expressed in insect cells to try to ascertain why human mast cells express these two nearly identical granule proteases. In contrast to that proposed by others, residue -3 in the propeptide did not appear to be essential for the three-dimensional folding, post-translational modification, and/or activation of this family of serine proteases. Both recombinant tryptases were functional and bound the active-site inhibitor diisopropyl fluorophosphate. However, they differed in their ability to cleave varied trypsin-susceptible chromogenic substrates. Structural modeling analyses revealed that tryptase alpha differs from tryptase beta/II in that it possesses an Asp, rather than a Gly, in one of the loops that form its substrate-binding cleft. A site-directed mutagenesis approach was therefore carried out to determine the importance of this residue. Because the D215G derivative of tryptase alpha exhibited potent enzymatic activity against fibrinogen and other tryptase beta/II-susceptible substrates, Asp215 dominantly restricts the substrate specificity of tryptase alpha. These data indicate for the first time that tryptases alpha and beta/II are functionally different human proteases. Moreover, the variation of just a single amino acid in the substrate-binding cleft of a tryptase can have profound consequences in the regulation of its enzymatic activity and/or substrate preference. (+info)