| 1. |
- Erjefält, Jonas, et al.
(författare)
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Association between inflammation and epithelial damage-restitution processes in allergic airways in vivo
- 1997
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Ingår i: Clinical and Experimental Allergy. - : Wiley. - 1365-2222 .- 0954-7894. ; 27:11, s. 1344-1355
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Associations between allergen challenge-induced sites of epithelial damage and the distribution of leucocytes and extravasated plasma remain unexplored. OBJECTIVE: To study neutrophils, eosinophils, and fibrinogen at allergen challenge-induced patchy epithelial damage-restitution sites in guinea-pig trachea. METHODS: After local challenge tracheal tissue (cryo sections and whole-mounts) and lumen (selective tracheal lavage) were examined at 1, 5, and 24 h. Eosinophils, neutrophils and fibrinogen were identified by histochemistry. RESULTS: Neutrophils increased markedly in tracheal lavage fluids and in tissue and were strongly associated with the challenge-induced epithelial craters of damage-restitution. At 1 and 24 h eosinophils were increased in the tracheal lumen whereas the surrounding tissue displayed a reversed pattern. Gels rich in fibrinogen, neutrophils, and eosinophils were present in epithelial crater areas, protruding into the lumen. Clusters of free eosinophil granules, Cfegs, released through lysis of eosinophils, and neutrophils with long cytoplasmatic protrusions abounded in these crater areas. CONCLUSION: The present findings provide important new insights into allergic airways where sites of epithelial damage-restitution processes emerge as the major loci for eosinophil, neutrophil, and plasma protein activities, the latter likely causing leukocyte adhesion and activation in vivo. The distribution of eosinophils in this study suggests roles of these cells both in airway mucosa and in regional lymph nodes. Based on the present study we also propose that lysis of eosinophils and Cfegs generation are a major paradigm for activation of these cells in vivo.
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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 barrier formation by airway basal cells
- 1997
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Ingår i: Thorax. - 1468-3296. ; 52:3, s. 213-217
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Epithelial shedding processes in airway inflammation and defence may produce damaged areas where basal cells are the main remaining epithelial cell type. The present study examines the capacity of basal cells to form an epithelial barrier structure after loss of columnar epithelial cells. METHODS: A technique was developed which allows selective removal of columnar epithelial cells from isolated airways. A drop of tissue adhesive glue was applied on the mucosal surface shortly after excision of guinea pig trachea and human bronchus. Gentle removal of the glue, together with attached columnar cells, left a single layer of cobbled, solitary basal cells. The tissue was kept in culture media. Morphological changes of the basal cells were monitored by immuno-histochemistry and scanning and transmission electron microscopy at several time points. RESULTS: After 20 minutes the basal cells had undergone extensive flattening and established contact with each other. The basement membrane thus became covered by a poorly differentiated epithelium in both guinea pig and human airways. Abundant interdigitating cytoplasmic protrusions were observed at cell borders. CONCLUSIONS: Basal cells promptly flatten out to cover the basement membrane at loss of neighbouring columnar cells. These data may explain why the epithelial barrier function may be uncompromised in desquamative airway diseases. Furthermore, they suggest the possibility that sacrificial release of columnar epithelial cells and prompt creation of a barrier structure constitute important roles of basal cells in airway defence against severe insults.
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| 4. |
- 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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| 5. |
- 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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| 6. |
- Erjefält, Jonas, et al.
(författare)
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Prompt epithelial damage and restitution processes in allergen challenged guinea-pig trachea in vivo
- 1997
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Ingår i: Clinical and Experimental Allergy. - : Wiley. - 1365-2222 .- 0954-7894. ; 27:12, s. 1458-1470
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Little is known about the induction and the morphology of epithelial damage, and of the ensuing epithelial restitution processes in allergic airways. OBJECTIVE: To examine epithelial damage and restitution in allergen challenged guinea-pig trachea. METHODS: Whole-mount techniques, transmission and scanning electron microscopy, cryosectioning, and histochemical staining were used. Cell proliferation was monitored by BrdU-immunohistochemistry. RESULTS: Allergen challenge produced patchy, crater-like, and leucocyte-rich epithelial damage sites. At 1, 5, and 24 h damage was associated with poorly differentiated epithelial restitution cells. Already at 1 h the epithelial craters had a floor of flattened restitution cells and the damaged areas comprised < 1% of the mucosal surface area (whole-mount preparations). In contrast, cryo sections displayed large areas (approximately 20%, 1 h) of denudation. Epithelial, and subepithelial (fibroblasts, smooth muscle) proliferation was increased 5 and 24 h after challenge (P < 0.01). CONCLUSION: Within 1 h allergen challenge has induced patchy damage sites where epithelial restitution is already advanced; although easily produced by cryosectioning frank denudation was not evident in whole-mount preparations. The present findings may explain the well maintained, functional tightness of allergic airways displaying epithelial damage, shedding, and even denudation. The present data also suggest the possibility that epithelial damage-restitution may be causative to allergic airway remodelling.
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| 7. |
- Greiff, Lennart, et al.
(författare)
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Effects of topical platelet activating factor on the guinea-pig tracheobronchial mucosa in vivo
- 1997
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 160:4, s. 387-391
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Tidskriftsartikel (refereegranskat)abstract
- Platelet activating factor (PAF) has been reported to produce a variety of airway effects including epithelial damage and increased airway-lung absorption of hydrophilic tracers. The present study examines effects of PAF on the guinea-pig tracheobronchial mucosa in vivo. Vehicle with and without PAF (4.0 and 8.0 nmol) was superfused onto the tracheobronchial mucosa. The levels of 125I-albumin, previously given intravenously, were determined in tracheobronchial lavage fluids as an index of mucosal exudation of plasma. The mucosa was also examined by scanning electron microscopy. In separate animals, 99mTc-DTPA (a low molecular weight, 492 Da, hydrophilic tracer) was superfused onto the mucosal surface through an oro-tracheal catheter, together with vehicle or PAF (8.0 nmol). A gamma camera determined the disappearance rate of 99mTc-DTPA from the airways as an index of mucosal absorption. PAF produced dose-dependent mucosal exudation of plasma up to 20-fold greater than control (P < 0.001). However, PAF did not damage the epithelium and the absorption ability of the airway mucosa was unaffected. The results, in contrast to previous reports, suggest that PAF may not readily damage the airway mucosa even at large exudative doses of the agent. The present finding support the view that the plasticity of the epithelial junctions allows the creation of valve-like paracellular pathways for unidirectional clearance of extravasated plasma into the airway lumen. We suggest that endogenous PAF may participate in first line respiratory defence reactions by causing lumenal entry of bulk plasma without harming the epithelium.
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| 8. |
- Korsgren, Magnus, et al.
(författare)
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Allergic eosinophil-rich inflammation develops in lungs and airways of B cell-deficient mice
- 1997
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Ingår i: Journal of Experimental Medicine. - 1540-9538. ; 185:5, s. 885-892
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Tidskriftsartikel (refereegranskat)abstract
- Immunoglobulins (Ig), particularly IgE, are believed to be crucially involved in the pathogenesis of asthma and, equally, in allergic models of the disease. To validate this paradigm we examined homozygous mutant C57BL/6 mice, which are B cell deficient, lacking all Ig. Mice were immunized intraperitoneally with 10 micrograms ovalbumin (OVA) plus alum, followed by daily (day 14-20) 30 min exposures to OVA aerosol (OVA/OVA group). Three control groups were run: OVA intraperitoneally plus saline (SAL) aerosol (OVA/SAL group); saline intraperitoneally plus saline aerosol; saline intraperitoneally plus OVA aerosol (n = 6-7). Lung and large airway tissues obtained 24 h after the last OVA or SAL exposure were examined by light microscopy and transmission electron microscopy (TEM). The Ig-deficient mice receiving OVA/ OVA treatment had swollen and discolored lungs and exhibited marked eosinophilia both in large airway subepithelial tissue (49.2 +/- 12.0 cells/mm basement membrane [BM] versus OVA/ SAL control 1.2 +/- 0.3 cells/mm BM; P < 0.001), and perivascularly and peribronchially in the lung (49.3 +/- 9.0 cells/unit area versus OVA/SAL control 2.6 +/- 0.6 cells/unit area; P < 0.001). The eosinophilia extended to the regional lymph nodes. TEM confirmed the subepithelial and perivascular localization of eosinophils. Mucus cells in large airway epithelium increased from 1.5 +/- 0.8 (OVA/SAL mice) to 39.5 +/- 5.7 cells/mm BM in OVA/OVA treated mice (P < 0.001). OVA/SAL mice never differed from the other control groups. Corresponding experiments in wild-type mice (n = 6-7 in each group) showed qualitatively similar but less pronounced eosinophil and mucus cell changes. Macrophages and CD4+ T cells increased in lungs of all OVA/OVA-treated mice. Mast cell number did not differ but degranulation was detected only in OVA/OVA-treated wild-type mice. Immunization to OVA followed by OVA challenges thus cause eosinophil-rich inflammation in airways and lungs of mice without involvement of B cells and Ig.
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| 9. |
- Korsgren, Magnus, et al.
(författare)
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Lack of systemic anaphylaxis and aeroallergen-induced airway plasma extravasation in allergic immunoglobulin-deficient mice
- 1999
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Ingår i: International Archives of Allergy and Immunology. - : S. Karger AG. - 1423-0097 .- 1018-2438. ; 118:1, s. 67-73
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In Ig-deficient mice allergen challenge-induced pulmonary late phase inflammation is at least as pronounced as in wild-type animals. This study investigates immediate hypersensitivity responses in these mice. METHODS: To examine the acute plasma extravasation response in airway tissue, immunized Ig-deficient and wild-type mice and sham-immunized wild-type controls were subjected to 15 min ovalbumin aerosol challenge. 125I-albumin was injected (i.v.) 1 min prior to challenge. Immediately after challenge 131I-albumin was injected and the experiment was terminated. Plasma and trachea were analyzed for 125I and 131I, and the amount of extravasated plasma in the trachea was calculated. To study the development of systemic anaphylaxis immunized Ig-deficient and wild-type animals received intravenous allergen challenge followed by determination of mast cell responses and plasma histamine levels. RESULTS: Allergen aerosol-exposed immunized wild-type mice exhibited marked plasma extravasation in the trachea (pd0.01 vs. wild-type controls), but in the corresponding Ig-deficient mice there was no increased extravasation. Immunized Ig-deficient mice receiving intravenous allergen challenge were resistant to anaphylactic shock. By contrast, the wild-type animals developed systemic anaphylaxis, accompanied by plasma extravasation, mast cell degranulation, elevated plasma histamine and rapid death. CONCLUSION: The present data are evidence that immunoglobulins are crucial for the development of immediate (type 1) responses. These findings together with our previous observations on late-phase pulmonary responses suggest that immediate hypersensitivity processes are unimportant for development of the late phase inflammation in the respiratory tract of mice.
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| 10. |
- Korsgren, Magnus, et al.
(författare)
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Neural expression and increased lavage fluid levels of secretoneurin in seasonal allergic rhinitis.
- 2003
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Ingår i: American Journal of Respiratory and Critical Care Medicine. - 1535-4970. ; 167:11, s. 1504-1508
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Tidskriftsartikel (refereegranskat)abstract
- Secretoneurin is a neuropeptide potentially involved in migration of eosinophils, monocytes, and dendritic cells. Whether secretoneurin is present in the human airway mucosa and whether it is released at ongoing allergic airway inflammation is currently unknown. In patients with allergic rhinitis, we have explored the occurrence of secretoneurin in nasal mucosal biopsies and lavage fluids before and during natural allergen exposure. Immunohistochemical analysis revealed an abundance of nerves displaying secretoneurin immunoreactivity, which were distributed predominantly around blood vessels and submucosal glands. A majority of nerve fibers containing vesicular acetylcholine transporter, tyrosine hydroxylase, calcitonin gene–related peptide, and vasoactive intestinal peptide were also secretoneurin-immunoreactive, indicating a localization of secretoneurin in cholinergic, adrenergic, and sensory nerves. Lavage fluid levels of secretoneurin were increased at allergen exposure (p < 0.01–0.05). Levels of secretoneurin did not correlate with eosinophil cationic protein ({rho} = 0.1, p = 0.7). We conclude that secretoneurin has a widespread occurrence in nasal mucosal nerves of patients with seasonal allergic rhinitis and that increased nasal lavage fluid levels of secretoneurin may characterize ongoing allergen exposure. These data favor a role of secretoneurin in the local traffic of immune cells in human airway mucosa.
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