Segment-selective absorption of lysozyme in the intestine

Takano, Mikihisa; Koyama, Yuka; Nishikawa, Hiromi; Murakami, Teruo; Yumoto, Ryoko

doi:10.1016/j.ejphar.2004.08.041

Cited by 39 publications

(36 citation statements)

References 23 publications

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“…The mRNA expressions of cytokeratin 19, caveolin-1␣, and two endocytic receptors, megalin and cubilin, were analyzed as described previously (38). Total RNA was isolated from RLE-6TN cells (passages 43 and 61 for cytokeratin 19 and cubilin, passage 46 for caveolin-1␣, and passage 38 for megalin) and from rat lung and renal cortex with Mag Extractor-RNA.…”

Section: Methodsmentioning

confidence: 99%

Clathrin-mediated endocytosis of FITC-albumin in alveolar type II epithelial cell line RLE-6TN

Yumoto¹,

Nishikawa²,

Okamoto³

et al. 2006

American Journal of Physiology-Lung Cellular and Molecular Phys

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-We examined mechanisms of FITC-albumin uptake by alveolar type II epithelial cells using cultured RLE-6TN cells. Alkaline phosphatase activity and the expression of cytokeratin 19 mRNA, which are characteristic features of alveolar type II epithelial cells, were detected in RLE-6TN cells. The uptake of FITCalbumin by the cells was time and temperature dependent and showed the saturation kinetics of high-and low-affinity transport systems. FITC-albumin uptake was inhibited by native albumin, by chemically modified albumin, and by metabolic inhibitors and bafilomycin A 1, an inhibitor of vacuolar H ϩ -ATPase. Confocal laser scanning microscopic analysis after FITCalbumin uptake showed punctate localization of fluorescence in the cells, which was partly localized in lysosomes. FITC-albumin taken up by the cells gradually degraded over time, as shown by fluoroimage analyzer after SDS-PAGE. The uptake of FITC-albumin by RLE-6TN cells was not inhibited by nystatin, indomethacin, or methyl-␤-cyclodextrin (inhibitors of caveolae-mediated endocytosis) but was inhibited by phenylarsine oxide and chlorpromazine (inhibitors of clathrin-mediated endocytosis) in a concentration-dependent manner. Uptake was also inhibited by potassium depletion and hypertonicity, conditions known to inhibit clathrin-mediated endocytosis. These results indicate that the uptake of FITC-albumin in cultured alveolar type II epithelial cells, RLE-6TN, is mediated by clathrin-mediated but not by caveolae-mediated endocytosis, and intracellular FITC-albumin is gradually degraded in lysosomes. Possible receptors involved in this endocytic system are discussed. albumin clearance; caveolae-mediated endocytosis; endocytic receptor; modified albumin; protein transport THE DISTAL AIR SPACES OF THE lung (alveolar region) are lined with a continuous epithelium comprising two major types of epithelial cells, type I and type II. Type I epithelial cells have a squamous morphology and cover ϳ90 -95% of the alveolar surface area. Type II cells are cuboidal epithelial cells and cover ϳ5-10% of the surface area, although the number of type II cells in alveolar epithelia is similar to or more than that of type I cells. Type II cells also serve as progenitors of type I cells (13,40). Alveolar lining fluid contains various physiologically important proteins such as albumin, immunoglobulin G, and transferrin. The concentration of albumin in alveolar fluid is usually much lower than that in the blood, whereas the concentration would increase to 40 -65% of plasma level in hydrostatic pulmonary edema and to 75-95% in lung injury pulmonary edema. The clearance of serum proteins from the alveolar space is a critical process in recovery from pulmonary edema and in maintaining the normal alveolar milieu (17,22). Therefore, understanding the mechanisms of protein transport in alveolar epithelial cells is important for the development of better therapeutic approaches. In addition, such information could provide new insights into improved strategies for pulmonary delivery of ex...

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Section: Methodsmentioning

confidence: 99%

Clathrin-mediated endocytosis of FITC-albumin in alveolar type II epithelial cell line RLE-6TN

Yumoto¹,

Nishikawa²,

Okamoto³

et al. 2006

American Journal of Physiology-Lung Cellular and Molecular Phys

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“…Megalin is a membrane protein molecule that binds to various protein molecules such as lysozyme [29], and is highly expressed in the ileal epithelium [34,36]. In lysozyme absorption, however, megalin might not be important and the cationic charge of lysozyme might be important in the rat small intestine [36]. In general, the intestinal epithelial surface is anionically charged, and intestinal absorption of a protein is, at least partially, determined by its cationic charge [26,36].…”

Section: Source Of Bactericidal Peptides In Rat Alimentary Tractmentioning

confidence: 99%

“…Thus, the apices of the intestinal villi are a site of active absorption of some molecules and particulates. Megalin is a membrane protein molecule that binds to various protein molecules such as lysozyme [29], and is highly expressed in the ileal epithelium [34,36]. In lysozyme absorption, however, megalin might not be important and the cationic charge of lysozyme might be important in the rat small intestine [36].…”

Section: Source Of Bactericidal Peptides In Rat Alimentary Tractmentioning

confidence: 99%

“…In lysozyme absorption, however, megalin might not be important and the cationic charge of lysozyme might be important in the rat small intestine [36]. In general, the intestinal epithelial surface is anionically charged, and intestinal absorption of a protein is, at least partially, determined by its cationic charge [26,36]. Lysozyme and defensin molecules are strongly cationic charged [6].…”

Section: Source Of Bactericidal Peptides In Rat Alimentary Tractmentioning

confidence: 99%

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Immunohistochemical Study on the Secretory Host Defense System of Bactericidal Peptides in Rat Digestive Organs

Yokoo

Miyata

Udayanga

et al. 2011

The Journal of Veterinary Medical Science

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ABSTRACT. To clarify the fundamental regulation mechanism against indigenous bacterial proliferation in the alimentary tract, we immunohistochemically examined the localization of 4 bactericidal peptides (BP) in the rat digestive exocrine glands. In the upper alimentary tract, lysozyme was detected in the gustatory, extraorbital lacrimal and parotid glands. Secretory phospholipase A2 (sPLA2) was detected in the extraorbital lacrimal glands. -defensin1 was detected in the gustatory and extraorbital lacrimal glands. -defensin2 was detected in the Harderian glands. In the stomach, -defensins were detected in the gastric superficial epithelial cells. In the small and large intestines, only lysozyme and sPLA2 were detected in the Paneth cells. In the cecum, all 4 BP were detected in the middle to apical portions of the crypts, and only sPLA2 was detected in the basal portion. No BP were localized in other exocrine glands associated with the alimentary tract. In addition, all 4 BP were also detected in the columnar epithelial cells of the apical portions of intestinal villi. In the intestinal superficial epithelial cells, lysozyme and -defensins were detected in the ascending colon, whereas only -defensin1 was detected in the descending colon and rectum. These results suggest that BP are mainly secreted from exocrine tissues in the initial portion of the digestive tract and play a role in host defense against indigenous bacteria throughout the digestive tract. Part of the BP in the chyme might be absorbed by the epithelium at the most inner sites of mucosae in the small and large intestines.KEY WORDS: bactericidal peptides, digestive organs, exocrine glands, immunohistochemistry, indigenous bacteria.

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“…22) The mechanisms of the absorption of macromolecules include paracellular passage and transcellular endocytosis. [27][28][29][30][31] Intestinal epithelial cells possess a negatively charged surface like other cells. The electrostatic interaction of protein with the intestinal epithelial cells may be a factor determining its intestinal absorption.…”

Section: Discussionmentioning

confidence: 99%

Enhancement of Gastrointestinal Absorption of Ovalbumin Caused by Spermine Induces an Increase in Plasma Histamine Levels in Mice Sensitized to Ovalbumin

Sugita

Takao

Sugino

et al. 2011

Biological & Pharmaceutical Bulletin

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The polyamines spermidine and spermine (SPM) and their precursor putrescine are ubiquitous polycationic compounds found in all mammalian cells. [1][2][3][4][5] These compounds are essential for the maintenance of cell growth in many tissues, and intracellular levels of polyamines are maintained within narrow limits.The polyamines are present in variable amounts in almost all food or foodstuffs. In humans, a typical diet might contribute hundreds of micromoles of polyamines per day to the gut lumen, 6,7) and ingested food may be the major source of polyamines in the lumen of the upper small bowel. Exogenous polyamines play a role in the maintenance of normal growth and function of the intestinal tract. 8,9) Oral administration of SPM induces precocious maturation of the intestine. [10][11][12][13][14][15] Oral polyamines have also been shown to have beneficial effects on healing 16,17) and prevention [18][19][20] of gastrointestinal damage.The gastrointestinal tract acts as a barrier against the invasion of exogenous proteins into the body. This barrier function is due to enzymes that degrade the proteins and also due to impermeability of the proteins to the membrane due to their large molecular weight. Because most food-originated proteins are digested in the gastrointestinal tract before absorption, naturally occurring protein uptake from the intestinal epithelium should be low. In reality, however, the barrier function of the small intestinal epithelium in mammals is incomplete and, to a limited extent, macromolecules can pass from the lumen into the circulation. 21,22) In an in situ loop study and in an in vivo oral absorption study, we showed that polyamines, especially SPM, can enhance the intestinal absorption of fluorescein isothiocyanatelabeled dextran (molecular weight (MW) 4400, FD-4), a hydrophilic model macromolecule, without causing any significant damage in the intestinal tract in rats.23) We also suggested that the absorption-enhancing mechanism of SPM partly includes opening the tight junctions of the epithelium via the paracellular route by measuring FD-4 permeation and transepithelial electrical resistance in the human intestinal Caco-2 cell line. We have speculated that excess absorption of macromolecules by the action of SPM, one of the compounds in food, has widespread health effects. Thus, modulation of the gastrointestinal epithelial barrier by ingested luminal polyamines may influence the induction of food allergies. Gastrointestinal permeability enhanced by daily ingestion of polyamines plays a part in the regulation of the induction of tolerance because oral tolerance induction is related to the gradual and continuous absorption of a food allergen. 24,25) In contrast, after sensitization to an antigen, an increase in gastrointestinal permeability by polyamines may facilitate the absorption of the allergen into the circulation and lead to an anaphylactic response as an immediate hypersensitivity reaction to the antigen.The aim of this study was to determine whether an SPMinduced increase...

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Segment-selective absorption of lysozyme in the intestine

Cited by 39 publications

References 23 publications

Clathrin-mediated endocytosis of FITC-albumin in alveolar type II epithelial cell line RLE-6TN

Clathrin-mediated endocytosis of FITC-albumin in alveolar type II epithelial cell line RLE-6TN

Immunohistochemical Study on the Secretory Host Defense System of Bactericidal Peptides in Rat Digestive Organs

Enhancement of Gastrointestinal Absorption of Ovalbumin Caused by Spermine Induces an Increase in Plasma Histamine Levels in Mice Sensitized to Ovalbumin

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