Ultrastructural immunoperoxidase demonstration of autologous albumin in the alveolar capillary membrane and in the alveolar lining material in normal rats.

Bignon, J; Chahinian, P; Feldmann, Gérard; Sapin, Catherine

doi:10.1083/jcb.64.2.503

Cited by 46 publications

(18 citation statements)

References 24 publications

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“…Autologous IgG is found in alveolar epithelial cell coats, tubular myelin, and free granular deposits, whereas autologous albumin is present on the surfaces of type II pneumocytes and in vesicles located on type I cells (9,10). Other investigators showed that type I and type II cells take up ferritin and horseradish peroxidase into vesicles (47,98,123), whereas type II cells internalize SP-A from the alveolar space by receptormediated endocytosis (94).…”

Section: Pathways and Mechanisms Of Lung Protein Clearancementioning

confidence: 99%

Protein transport across the lung epithelial barrier

Kim

Malik

2003

American Journal of Physiology-Lung Cellular and Molecular Phys

181

130

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. Because concentrations of plasma proteins in alveolar fluid can increase in injured lungs (such as with permeability edema and inflammation), understanding how alveolar epithelium handles protein transport is needed to develop therapeutic measures to restore alveolar homeostasis. This review provides an update on recent findings on protein transport across the alveolar epithelial barrier. The use of primary cultured rat alveolar epithelial cell monolayers (that exhibit phenotypic and morphological traits of in vivo alveolar epithelial type I cells) has shown that albumin and IgG are absorbed via saturable processes at rates greater than those predicted by passive diffusional mechanisms. In contrast, secretory component, the extracellular portion of the polymeric immunoglobulin receptor, is secreted into alveolar fluid. Transcytosis involving caveolae and clathrincoated pits is likely the main route of alveolar epithelial protein transport, although relative contributions of these internalization steps to overall protein handling of alveolar epithelium remain to be determined. The specific pathways and regulatory mechanisms responsible for translocation of proteins across lung alveolar epithelium and regulation of the cognate receptors (e.g., 60-kDa albumin binding protein and IgG binding FcRn) expressed in alveolar epithelium need to be elucidated. alveolar epithelial cells; albumin; secretory component; immunoglobulin G MACROMOLECULE TRANSPORT ACROSS alveolar epithelium has been investigated over the years, but little is known to date concerning the mechanisms and underlying pathways regulating transalveolar protein clearance. Alveolar protein clearance is fundamental to the resolution of the transudate and exudate after hydrostatic-and especially high permeability-type pulmonary edema. The inability to clear excess proteins from air spaces is associated with poor prognosis in patients with alveolar flooding pulmonary edema. Clearance of edema fluid via active ion transport processes raises the oncotic pressure that, in the absence of efficient clearance mechanisms for proteins, slows alveolar fluid clearance. Patients with acute respiratory distress syndrome (ARDS), for example, have large quantities of precipitated protein in their air spaces (3), and nonsurvivors have three times more protein in their air spaces than survivors (21). In addition, excess serum proteins in alveolar edema fluid may lead to precipitation and modification of proteins (e.g., by reactive oxygen and nitrogen species). Although macrophages may contribute to clearance of the excess proteins, the integrity of the alveolar epithelial barrier may not be readily re-

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Section: Pathways and Mechanisms Of Lung Protein Clearancementioning

confidence: 99%

Protein transport across the lung epithelial barrier

Kim

Malik

2003

American Journal of Physiology-Lung Cellular and Molecular Phys

181

130

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“…However, the ruthenium red-positive material in both the hypophase and the matrix of tubular-myelin figures observed, is presumed to be glycoprotein, even though the acid mucopolysaccharide nature cannot be completely ruled out. Because concanavalin A-reactive carbohydrate (9,27) and protein (4,5,45) have also been demonstrated in both the hypophase and the matrix of tubular-myelin figures. In addition, it has been indicated by Luft (25) that ruthenium red can react not only with acid mucopolysaccharide, but also with protein, other polysaccharide, phospholipid and nucleic acid.…”

Section: Resultsmentioning

confidence: 99%

“…Kikkawa et al (22) have reported with the use of fixation by immersion of the whole lung that the colloidal iron-positive material is observed on the microvillous surface of the type II cell but not on the surface of the type I cell. Bignon et al (4,5) and Sueishi et al (45) have demonstrated the presence of proteins in the hypophase and in the matrix material of tubular-myelin figures using the perfusionfixation technique. Roth (42), with the use of immersion-fixation of the whole lung, 647 and Nir and Pease (32), with the use of fixation by vascular perfusion, have demonstrated that the distribution of the concanavalin A-reactive carbohydrate apparently coincides with the distribution of protein demonstrated by Bignon et al (4,5) and Sueishi et al (45), suggesting both may be associated as a glycoprotein.…”

mentioning

confidence: 99%

Ultrahistochemical Study of Mucopolysaccharide at the Surface of the Alveolar Epithelium in a Rat Lung

Iwatsuki

1980

Acta Histochem. Cytochem

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The ultrastructural localization of mucopolysaccharide in the pulmonary alveolus of a rat was studied by means of the colloidal iron reaction, the ruthenium red staining and the phosphotungstic acid (PTA) staining. Colloidal iron-positive material was observed in a thin layer, 15-25 nm in thickness, closely attached to the luminal surface of the alveolar epithelium. The superficial layer, the hypophase, and the tubular-myelin figures, however, lacked the colloidal iron reactivity.Ruthenium red-positive material was observed on the luminal surface of the alveolar epithelium as well as in the hypophase.In the ultrathin sections stained with PTA (pH 0.4 and 1.5), the microvillous surface of the type II cell was densely stained, whereas the luminal surface of the type I cell was not discernible.The results suggest that acid mucopolysaccharide is not involved in the surfactant lining, but may be in existence as a surface coat on the alveolar epithelium; the surface coat on the type II cell differs chemically from that on the type I cell.Since Macklin (28) first described the presence of a lining layer on the alveolar surface, a number of histochemical and ultrahistochemical studies indicated that the lining layer consisted of neutral lipids (12, 23, 31), phospholipids (1, 6, 11, 12), proteins (20, 34) and mucopolysaccharides having affinities for colloidal iron (3,16,17,24,28,29), periodic acid-Schiff (3, 6, 9, 27), alcian blue (27), low iron diamine (27), ruthenium red (1,7,17,29, 33), chromic phosphotungstic acid (PTA) (1), concanavalin A (41) and high iron diamine (19). However, no relationship of these components to the surfactant lining was apparent, since in those experiments most of the surfactant lining was removed during the fixation procedure.Weibel and Gil (47) and Gil and Weibel (14) observed with the use of fixation by vascular perfusion that the surfactant lining of the pulmonary alveoli had two phases, namely an osmiophilic superficial layer (epiphase) and a homogeneous basal layer (hypophase). Kikkawa (21) obtained similar results by immersion-fixation of the whole lung. Thereafter, it has become possible by taking advantage of these fixation procedures to demonstrate the precise localization of surfactant components. Kikkawa et al. (22) have reported with the use of fixation by immersion of the whole lung that the colloidal iron-positive material is observed on the microvillous surface of the type II cell but not on the surface of the type I cell. Bignon et al. (4,5) and Sueishi et al. (45) have demonstrated the presence of proteins in the hypophase and in the matrix material of tubular-myelin figures using the perfusionfixation technique. Roth (42), with the use of immersion-fixation of the whole lung, 646

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“…However, many other studies haye been made which neither support phospholipid secretion by the Clara cell nor phagocytic activity for the type II cell. The major protein component of pulmonary lavage effluents is albumin which has been shown, using immunochemical methods, to be a normal constituent of the extracellular lining (27). Similar immunochemical methods have been used to show the presence of IgG at the lining (28).…”

Section: The Extracellular Liningmentioning

confidence: 99%