| 1. |
- Elovsson, Sofia, et al.
(författare)
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Evaluation of nasal barrier dysfunction at acute- and late-phase reactions in a guinea pig model of allergic rhinitis
- 2005
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Ingår i: Vascular Pharmacology. - : Elsevier BV. - 1537-1891. ; 43:4, s. 267-276
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Tidskriftsartikel (refereegranskat)abstract
- Allergic rhinitis is a common disease characterized by the symptoms of pruritus, sneezing, hypersecretion and nasal blockage. Increased mucosal barrier permeability has been suggested to be an indicator for the severity of allergic rhinitis. This study investigates the passage of radiolabelled albumin from the nasal mucosal circulation into the lumen in guinea pigs intraperitoneally sensitized and intranasally challenged with antigen. In order to characterize the allergic rhinitis model, we evaluated a number of potential influencing factors in nasal plasma exudation, including antigen doses, volumes of antigen solution used, and animal position during the nasal lavage, and the conditions of nasal lavage. The number of eosinophils and levels of histamine and leukotriene B4 in the nasal lavage and eosinophils in the nasal mucosa were determined at the early and late phases after antigen challenge. We also compared the effects of topical nasal treatments for allergic rhinitis on nasal inflammatory responses. Our results demonstrate that, in the guinea pig nasal mucosa, topical challenge with antigens induces plasma exudation and histamine release at the acute-phase reaction, and plasma exudation and eosinophil infiltration at the late-phase reaction. These changes are similar to those reported in human allergic rhinitis. Alterations of nasal plasma exudation, histamine release and eosinophil influx were dependent upon the concentrations and volumes of antigens. An antihistamine inhibited the acute-phase reaction partially, whereas budesonide inhibited effects at the late-phase reaction. We suggest that this model of guinea pig allergic rhinitis with the early and late responses may be useful for high-throughout screening of new drugs.
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| 2. |
- Erjefält, Jonas, et al.
(författare)
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Effects of topical budesonide on epithelial restitution in vivo in guinea pig trachea
- 1995
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Ingår i: Thorax. - 1468-3296. ; 50:7, s. 785-792
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND--Continuous epithelial shedding and restitution processes may characterise the airways in diseases such as asthma. Epithelial restitution involves several humoral and cellular mechanisms that may potentially be affected by inhaled anti-asthma drugs. The present study examines the effect of a topical steroid on epithelial restitution in vivo in the guinea pig. METHODS--The airway epithelium was mechanically removed from well defined areas of guinea pig trachea without surgery and without damage to the basement membrane or bleeding. An anti-inflammatory dose of budesonide (1 mg) was administered repeatedly to the tracheal surface by local superfusion 24 hours before, at (0 hours), and 24 hours after the denudation. Migration of epithelial cells, formation of a plasma exudation-derived gel, and appearance of luminal leucocytes were recorded by scanning electron microscopy. Cell proliferation was visualised by bromodeoxyuridine immunohistochemistry and tissue neutrophils and eosinophils by enzyme histochemistry. RESULTS--Immediately after creation of the denuded zone ciliated and secretory cells on its border dedifferentiated, flattened out, and migrated speedily (mean (SE) 2.3 (0.3) micron/min) over the basement membrane. After 48 hours the entire denuded zone (800 microns wide) was covered by a tightly sealed epithelium; at this time increased proliferation was observed in new and old epithelium and subepithelial cells. Budesonide had no detectable effect on epithelial dedifferentiation, migration, sealing, or proliferation. Immediately after denudation and continuously during the migration phase plasma was extravasated creating a fibrinous gel rich in leucocytes, particularly neutrophils, over the denuded area. Budesonide had no effect on either the gel or the leucocyte density. CONCLUSIONS--These observations suggest that topical glucocorticoids may not interfere with a fast and efficient restitution of the epithelium in the airways.
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| 3. |
- Erjefält, Jonas, et al.
(författare)
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Epithelial pathways for luminal entry of bulk plasma
- 1995
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Ingår i: Clinical and Experimental Allergy. - : Wiley. - 1365-2222. ; 25:2, s. 187-195
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Tidskriftsartikel (refereegranskat)abstract
- Inflammatory challenges of the airway mucosa cause luminal entry of bulk plasma. Extravasation of plasma is well described but the routes for epithelial passage of plasma are largely unknown. Using colloidal gold (5 nm) as tracer we have now examined the fate of extravasated plasma in the airways. The tracer was given intravenously to anaesthetized, ovalbumin-sensitized guinea-pigs 2min prior to airway mucosal challenge with 12pmol ovalbumin (the dose was selected from a separate dose-response study). Tissue specimens were collected 30s, 3 and 6 min after end of challenge (separate time course experiments suggested that the peak rate of entry of plasma occurred at about 5 min). The colloidal gold particles were visualized by autometallographic silver intensification. The gold produced no circulatory disturbance and had a uniform vascular distribution with negligible adherence to vascular endothelium. After challenge gold was first widely distributed in the lamina propria. At 3 and 6 min the tracer was also in the epithelium and airway lumen. It appeared that plasma was moved distinctly between and all around each epithelial cell. Bright field-, scanning-, and transmission electron-microscopy indicated that the luminal entry of plasma did not affect the integrity of the epithelial lining. This study demonstrates that the plasma exudate moves across an intact epithelial layer through ubiquitous paracellular pathways. Even at a pronounced acute plasma exudation response exceedingly small amounts of plasma may pass around a single cell explaining the non-injurious nature of mucosal exudation of bulk plasma in health and disease.
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| 4. |
- Erjefält, Jonas, et al.
(författare)
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In vivo restitution of airway epithelium
- 1995
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Ingår i: Cell and Tissue Research. - 1432-0878. ; 281:2, s. 305-316
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Tidskriftsartikel (refereegranskat)abstract
- Epithelial shedding occurs in health and, extensively, in inflammatory airway diseases. This study describes deepithelialisation, reepithelialisation and associated events in guinea-pig trachea after shedding-like epithelial denudation in vivo. Mechanical deepithelialisation of an 800-microns wide tracheal zone was carried out using an orotracheal steel probe without bleeding or damage to the basement membrane. Reepithelialisation was studied by scanning- and transmission electron microscopy and light microscopy. Nerve fibres were examined by immunostaining. Cell proliferation was analysed by [3H]-thymidine autoradiography. Immediately after epithelial removal secretory and ciliated (and presumably basal) epithelial cells at the wound margin dedifferentiated, flattened and migrated rapidly (2-3 microns/min) over the denuded basement membrane. Within 8-15 h a new, flattened epithelium covered the entire deepithelialised zone. At 30 h a tight epithelial barrier was established and after 5 days the epithelium was fully redifferentiated. After completed migration an increased mitotic activity occurred in the epithelium and in fibroblasts/smooth muscle beneath the restitution zone. Reinnervating intraepithelial calcitonin gene-related peptide-containing nerve fibres appeared within 30 h. We conclude that (1) reproducible shedding-like denudation, without bleeding or damage to the basement membrane, can be produced in vivo; (2) secretory and ciliated cells participate in reepithelialisation by dedifferentiation and migration; (3) the initial migration is very fast in vivo; (4) shedding-like denudation may cause strong secretory and exudative responses as well as proliferation of epithelium, and fibroblasts/smooth muscle. Rapid restitution of airway epithelium may depend on contributions from the microcirculation and innervation.
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