Persorption of IgG-Fc-Coated Particulates from Intestinal Lumen into Portal Blood via Villous Columnar Epithelial Cells in Rat Small Intestine

Abstract

ABSTRACT. Previously, the specific antibody-mediated persorption of antigenic molecules and particulates from the small-intestinal lumen into the peripheral blood was clarified in rats, but the intermediation of the receptor for the specific antibodies was not. In this study, the existence of receptor for the specific antibody was experimentally examined in the rat small intestine. Glutaraldehyde-fixed sheep erythrocytes (SEs) coated by Fc-fragments of IgG (IgG-Fc), (Fab′) 2 -fragments of IgG (IgG-Fab) or bovine serum albumin (BSA), were injected into 3 jejunal loops each 2 cm in length in non-orally pre-immunized rats, respectively. Thirty minutes after the injection, IgG-Fc-coated SEs were significantly more engulfed by villous columnar epithelial cells than Fab-or BSA-coated SEs. The most frequent absorption sites were the intestinal villous apices. The IgG-Fc-coated SEs were adhered to the striated borders and were engulfed by villous columnar epithelial cells. IgG-Fc-coated SEs passing through the epithelial cells were also detected in the subepithelial blood capillaries just beneath the villous epithelium, but not in the connective tissue and the lymph vessels. These findings suggest that the absorption of luminal antigenic particulates is probably mediated by the Fc-receptor, and that the absorbed antigenic particulates are directly transferred to the hepatic portal blood by passing through the endothelium of the subepithelial blood capillaries.

Ultrastructural Demonstration of the Absorption and Transportation of Minute Chylomicrons by Subepithelial Blood Capillaries in Rat Jejunal Villi

“…The number of persorbed particulates from the intestinal lumen is significantly greater in the portal blood than in the systemic circulating blood in rats [39]. Moreover, the direct crossing of the endothelium by sBCs has been histologically demonstrated by luminal administration of IgG-Fc fragment-coated particulates into the rat jejunum [40]. In the present study, the number of chylomicrons in the venules of the intestinal villi was greater than that in the arterioles in the submucosa.…”

“…On the other hand, a phenomenon known as “persorption,” by which various substances or particulates in the intestinal lumen are directly transported into the blood circulation without any digestion, has been reported in humans and various animal species [34]. In persorption, both specific antibodies against the ingested substances and epithelial receptors for IgG-Fc fragments probably play an important role [38,39,40]. Furthermore, the direct entry of luminal particulates into the sBCs has been histologically demonstrated in intestinal villi of the rat jejunum [40].…”

“…In persorption, both specific antibodies against the ingested substances and epithelial receptors for IgG-Fc fragments probably play an important role [38,39,40]. Furthermore, the direct entry of luminal particulates into the sBCs has been histologically demonstrated in intestinal villi of the rat jejunum [40]. From these reports, the sBCs in the intestinal villi are assumed to be special blood vessels that can absorb and transport macromolecules or particulates, including chylomicrons, from the extravascular tissue.…”

Effect of the First Feeding on Enterocytes of Newborn Rats

“…The role of the affinity of receptors to Fc fragments of IgG is important for apical endocytosis. Indeed, IgG-Fc-coated particulates, including even erythrocytes, are subjected to persorption from intestinal lumen via villous columnar epithelial cells in the small intestine [63]. In early embryonic development, access of maternally deposited nuclear proteins to the genome is temporally ordered via importin affinities [64].…”

Intestinal Macromolecular Transport Supporting Adaptive Immunity

“…However, although earlier studies suggested an association of apoptosis with persorption by morphologic appearance, GAP formation was not associated with goblet cell apoptosis as determined by immunofluorescence staining 39 . In addition, it has been observed that persorption was increased by antibody coating, suggesting that although this process may not require antibody coating, it may be facilitated by fragment crystallizable region (Fc)-receptor binding, 71 a process that has not been evaluated in antigen delivery by GAPs. In support of a link between persorption and GAP formation, persorption was inhibited by the panmuscarinic receptor agonist atropine and further induced by the acetylcholinesterase inhibitor prostigmine, 65 which increases acetylcholine levels.…”