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| 2. |
- Erjefält, Jonas, et al.
(författare)
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Airway epithelial repair: breathtakingly quick and multipotentially pathogenic
- 1997
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Ingår i: Thorax. - 1468-3296. ; 52:11, s. 1010-1012
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Tidskriftsartikel (refereegranskat)abstract
- Epithelial shedding, even to the point of airway denudation, had already been described as a common and unifying feature of asthma by the latter half of the 19th century. However, the repair processes that specifically follow the shedding-like loss of epithelial cells have only recently been examined in vivo. This paper discusses the exceedingly fast epithelial restitution and the potential pathogenic sequelae to epithelial shedding alone that have been unravelled. Epithelial cytoprotection emerges as an important property of future therapeutic drugs for the treatment of airways inflammatory conditions.
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| 3. |
- Erjefält, Jonas
(författare)
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Airway epithelial shedding: Morphological and functional aspects in vivo.
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Epithelial damage may contribute to the pathology in airway diseases such as asthma and rhinitis. However, the distribution of epithelial shedding in inflammatory airway diseases and, particularly, the ensuing repair processes are largely unknown. In the present studies we have developed novel in vivo techniques to explore epithelial repair mechanisms and associated tissue responses occuring in guinea-pig trachea after mechanical-induced epithelial shedding or an allergic inflammation. The results emerging from the studies of mechanichal shedding and repair include: morphological characterisation of prompt dedifferentiation of both ciliated and secretory epithelial cells into repair cells that with a high speed migrate to cover the denuded basement membrane. Another major finding was that epithelial shedding, by itself, evoked several disease-like tissue responses such as plasma exudation, hypersecretion, and infiltration and activation of neutrophils and eosinophils. Repeated treatment with a potent topical glucocorticoid (budesonide) did not affect the speedy epithelial restitution and its associated tissue responses. A novel technique was developed to selectively remove columnar epithelial cells to demonstrate that also airway basal cells have a capacity to promptly assume a barrier structure. In vivo allergen challenge, selectively of the large airways, produced crater-like damage sites in the epithelium. Dedifferentiated repair cells were present at the floor and the borders of these damage sites. Activated granulocytes and extravasated plasma proteins abounded in the airways, particularly in association with the damage sites. In conclusion this thesis demonstrates that epithelial repair after mechanical or allergen-induced epithelial shedding is a speedy an efficient process with the participation of basal, secretory, and ciliated cells in a milieu of plasma exudates and leukocytes. This thesis further shows that in allergic inflammation patchy epithelial damage areas are dynamic sites where damage and repair processes occur simultaneously and where plasma exudates and activated leukocytes accumulate. If transferable to human airways the present observations on sequelae to epithelial shedding suggest that epithelial restitution processes quickly restore a barrier structure but causes also effects that significantly contribute to the pathology and pathophysiology observed in inflammatory airway diseases.
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| 4. |
- Erjefält, Jonas, et al.
(författare)
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Allergen challenge-induced extravasation of plasma in mouse airways
- 1998
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Ingår i: Clinical and Experimental Allergy. - : Wiley. - 1365-2222 .- 0954-7894. ; 28:8, s. 1013-1020
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Mouse models are extensively used to study genetic and immunological mechanisms of potential importance to inflammatory airway diseases, e.g. asthma. However, the airway pathophysiology in allergic mice has received less attention. For example, plasma extravasation and the ensuing tissue-deposition of plasma proteins, which is a hallmark of inflammation, has not been examined in allergic mice. OBJECTIVE: This study aims to examine the vascular permeability and the distribution of plasma proteins in mouse airways following exposure to allergen and serotonin. METHODS: Extravasated plasma was quantified by a dual isotop technique using intravascular (131I-albumin) and extrasvascular (125I-albumin) plasma tracers. Histological visualization of fibrinogen and colloidal gold revealed the tissue distribution of extravasated plasma. RESULTS: Allergen aerosol exposure (3% OVA, 15min) of sensitized animals resulted in a marked plasma extravasation response in the trachea (P < 0.01) and the bronchi but not in the lung parenchyma. A similar extravasation response was induced by serotonin (P<0.001). Extravasating vessels (assessed by Monastral blue dye) were identified as intercartilaginous venules. Extravasated plasma abounded in the subepithelial tissue but was absent in the epithelium and airway lumen. The allergen-induced response was dose-dependently inhibited by iv administration of formoterol (P < 0.001), a vascular antipermeability agent. CONCLUSION: The present study demonstrates that serotonin and allergen challenge of sensitized mice increase airway venular permeability to cause transient extravasation and lamina propria distribution of plasma in the large airways. We suggest that the extravasation response is a useful measure of the intensity and the distribution of active inflammation
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| 5. |
- Erjefält, Jonas, et al.
(författare)
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Allergen-induced eosinophil cytolysis is a primary mechanism for granule protein release in human upper airways
- 1999
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Ingår i: American Journal of Respiratory and Critical Care Medicine. - 1535-4970. ; 160:1, s. 304-312
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Tidskriftsartikel (refereegranskat)abstract
- Cytotoxic eosinophil granule proteins are considered important in the pathogenesis of allergic airway diseases such as rhinitis and asthma. To explore the cellular mechanisms behind eosinophil granule release in human allergic airways, 16 symptom-free patients with seasonal allergic rhinitis were challenged daily with allergen during 1 wk. Nasal lavage samples and biopsies, obtained before and 24 h after the last allergen exposure, were processed for immunohistochemical and electron microscopic analysis. The allergen challenges produced nasal symptoms, marked tissue eosinophilia, and an increase in lavage fluid levels of eosinophil cationic protein (ECP). The nasal mucosa areas with intense extracellular immunoreactivity for ECP were associated with abundant free eosinophil granules. Electron microscopy confirmed the free granules and revealed that all mucosal eosinophils were involved in granule release, either by cytolysis (33%) or piecemeal degranulation (PMD) (67%). Resting or apoptotic eosinophils were not observed. Cytolytic eosinophils had less signs of intracellular granule release (p < 0. 001) and a higher content of intact granules (p < 0.001) compared with viable eosinophils in the same tissue. This study demonstrates eosinophil cytolysis (ECL) as a distinct mechanism for granule mediator release in human allergic airway mucosa. The nature and extent of the ECL and its product (i.e., protein-laden extracellular granules) indicate that allergen-induced cytolysis is a primary and major mechanism for the release of eosinophil proteins in human allergic airway inflammation in vivo.
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| 6. |
- 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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| 7. |
- Erjefält, Jonas, et al.
(författare)
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Cytolysis and piecemeal degranulation as distinct modes of activation of airway mucosal eosinophils
- 1998
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Ingår i: Journal of Allergy and Clinical Immunology. - 1097-6825. ; 102:2, s. 286-294
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cytotoxic eosinophil granule proteins are considered important in the pathogenesis of inflammatory airway diseases, including asthma, rhinitis, and polyposis. However, little is known about the mechanisms involved in the deposition of these tissue-damaging granular products in vivo. OBJECTIVE: We sought to determine the occurrence of degranulating eosinophils, those with morphologic evidence of cytolysis with associated clusters of free eosinophil granules (Cfegs), and to identify the frequency of apoptotic eosinophils in inflamed upper airway tissue. METHODS: Eosinophil-rich nasal polyps were processed for transmission electron microscopy and for light microscopic evaluation of whole-mount preparations subjected to deep tissue staining for eosinophil peroxidase. RESULTS: The mean proportion of eosinophil subtypes were intact and resting (6.8%), intact but degranulating (83%), cytolytic or Cfegs (9.9%), and apoptotic (0.0%). All degranulating eosinophils exhibited piecemeal degranulation. The occurrence of Cfegs was confirmed in nonsectioned whole-mount preparations. Depending on the appearance of their core and matrix, the specific granules were divided into four subtypes, and a degranulation index (altered per total granules) was calculated for each eosinophil. Cytolytic eosinophils had a much lower degranulation index than intact eosinophils present in the same tissue (P < .001). CONCLUSIONS: These data indicate that eosinophil cytolysis is present in human airway mucosa, that its occurrence is not an artifact of the means of tissue handling, and that cytolysis of eosinophils may occur without prior extensive degranulation. We suggest that eosinophil cytolysis is a major activation mechanism, which occurs along with, but is distinct from, other types of degranulation.
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| 8. |
- 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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| 9. |
- Erjefält, Jonas, et al.
(författare)
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Eosinophils, neutrophils, and venular gaps in the airway mucosa at epithelial removal-restitution
- 1996
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Ingår i: American Journal of Respiratory and Critical Care Medicine. - 1535-4970. ; 153:5, s. 1666-1674
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Tidskriftsartikel (refereegranskat)abstract
- Shedding of epithelium, increased venular permeability, and traffic of activated eosinophils and neutrophils may characterize asthmatic airways. This in vivo study involving briefly anesthetized guinea pigs examines whether epithelial denudation itself affects airway venules and granulocytes. Using an oral probe, a de-epithelialized tracheal zone (0.8 x 30 mm) was produced without bleeding or damage to the basement membrane. After 10 min, 2, 8, and 48 h, the tracheal tissue was examined by scanning and transmission electron microscopy. Silver staining revealed endothelial cell borders. Histochemistry identified neutrophils and eosinophils. Confirming previous observations, epithelial restitution started promptly and occurred speedily under a plasma exudation-derived, leukocyte-rich gel. Ten minutes after de-epithelialization, venular gaps (silver dots) were recognized as plasma exudation sites and, separately, silver rings at endothelial cell borders indicated attachment and extravasation of leukocytes. Tissue neutrophils were increased from 10 min to 48 h. Normally occurring eosinophils decreased in numbers during re-epithelialization, partly due to migration into the airway lumen and local cell death. Clusters of extracellular eosinophil granules were increased from 10 min to 8 h. Gentle removal of airway epithelium thus produced venular gaps, infiltration of neutrophils, and migration, activation, and death of eosinophils. Epithelial shedding-restitution processes may cause part of the microvascular and leukocyte changes that occur in inflammatory airway diseases.
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| 10. |
- 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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