| 1. |
|
|
| 2. |
- Erjefält, Jonas, et al.
(författare)
-
Association between inflammation and epithelial damage-restitution processes in allergic airways in vivo
- 1997
-
Ingår i: Clinical and Experimental Allergy. - : Wiley. - 1365-2222 .- 0954-7894. ; 27:11, s. 1344-1355
-
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.
|
|
| 3. |
- Erjefält, Jonas, et al.
(författare)
-
Effects of topical budesonide on epithelial restitution in vivo in guinea pig trachea
- 1995
-
Ingår i: Thorax. - 1468-3296. ; 50:7, s. 785-792
-
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.
|
|
| 4. |
- Erjefält, Jonas, et al.
(författare)
-
Eosinophils, neutrophils, and venular gaps in the airway mucosa at epithelial removal-restitution
- 1996
-
Ingår i: American Journal of Respiratory and Critical Care Medicine. - 1535-4970. ; 153:5, s. 1666-1674
-
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.
|
|
| 5. |
- Erjefält, Jonas, et al.
(författare)
-
Epithelial barrier formation by airway basal cells
- 1997
-
Ingår i: Thorax. - 1468-3296. ; 52:3, s. 213-217
-
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.
|
|
| 6. |
- Erjefält, Jonas, et al.
(författare)
-
Epithelial pathways for luminal entry of bulk plasma
- 1995
-
Ingår i: Clinical and Experimental Allergy. - : Wiley. - 1365-2222. ; 25:2, s. 187-195
-
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.
|
|
| 7. |
- Erjefält, Jonas, et al.
(författare)
-
In vivo restitution of airway epithelium
- 1995
-
Ingår i: Cell and Tissue Research. - 1432-0878. ; 281:2, s. 305-316
-
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.
|
|
| 8. |
- Erjefält, Jonas, et al.
(författare)
-
Microcirculation-derived factors in airway epithelial repair in vivo
- 1994
-
Ingår i: Microvascular Research. - : Elsevier BV. - 1095-9319 .- 0026-2862. ; 48:2, s. 161-178
-
Tidskriftsartikel (refereegranskat)abstract
- Airway epithelial repair, by cell migration over a denuded, intact basement membrane, occurs rapidly in vivo. The present study examines microcirculation-derived factors in the reepithelialization process in the guinea pig. A well-defined tracheal zone was gently deepithelialized; no bleeding occurred and the basement membrane was left intact. Plasma exudation was visualized by use of iv colloidal gold (diameter: 5 nm) or fluoresceinisothiocyanate-labeled dextran. Scanning and transmission electron microscopy confirmed the migration of epithelial cells and, additionally, allowed us to examine the presence of an extracellular matrix gel and leukocytes on the denuded basement membrane. Fibronectin was analyzed by immunocytochemistry. Following epithelial removal plasma promptly extravasates and produces a fibrin-fibronectin gel to cover the denuded basement membrane. Epithelial cells dedifferentiate, flatten, and migrate rapidly (several micron/min) beneath the plasma-derived gel. Within 30 min the gel contains numerous leukocytes, some of which are eosinophils. Plasma exudes into the gel until about 8 hr by which time the entire denuded zone (800 microns) is covered by squamous epithelium. The fibrin-fibronectin gel is suggested to be exclusively plasma-derived. In conclusion, reepithelialization in vivo occurs beneath a gel containing adhesive plasma proteins and leukocytes. We suggest that a plasma exudate provides immediate cover of denuded airway basement membrane and that plasma- and leukocyte-derived factors contribute essentially to reepithelialization in vivo.
|
|
| 9. |
- Erjefält, Jonas, et al.
(författare)
-
Mucosal nitric oxide may tonically suppress airways plasma exudation
- 1994
-
Ingår i: American Journal of Respiratory and Critical Care Medicine. - 1535-4970. ; 150:1, s. 227-232
-
Tidskriftsartikel (refereegranskat)abstract
- In a search for airway epithelial mechanisms that may affect the subepithelial microcirculation, we examined plasma exudation responses to NG-nitro-L-arginine-methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor. L-NAME was applied topically on the tracheal mucosa of guinea pigs that had previously received 125I-albumin and/or colloidal gold particles (5 nm) intravenously. Luminal entry of plasma was determined by the levels of 125I-albumin in tracheal lavage fluid. Topical L-NAME (2.2, 9, and 22 mumol), but not intravenous L-NAME (375 mumol/kg), produced plasma exudation into the airway lumen (p < 0.01 to p < 0.001). The L-NAME enantiomer NG-nitro-D-arginine-methyl ester (D-NAME, 9 mumol) produced no exudative response. Coadministration of L-arginine (27 mumol) abolished the L-NAME-induced exudation. The extravasated plasma was distributed in the lamina propria and between epithelial cells (colloidal gold). The epithelial surface structure (scanning electron microscopy) appeared intact. Staining with nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase suggested that epithelial basal may contain nitric oxide synthases. We suggest that endogenously released nitric oxide from epithelial or other superficial cells tonically suppresses the macromolecular permeability of the subepithelial microcirculation.
|
|
| 10. |
- Erjefält, Jonas, et al.
(författare)
-
Prompt epithelial damage and restitution processes in allergen challenged guinea-pig trachea in vivo
- 1997
-
Ingår i: Clinical and Experimental Allergy. - : Wiley. - 1365-2222 .- 0954-7894. ; 27:12, s. 1458-1470
-
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.
|
|
