Uptake of polypeptide fragments of proteins by rat intestine in vitro and in vivo

Kj, Bloch; Ja, Wright; Sm, Bishara; Mb, Bloch

doi:10.1016/0016-5085(88)90361-7

Cited by 15 publications

(6 citation statements)

References 15 publications

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“…The method by which the human gut might absorb such large protein fragments is unclear although the transcytosis of IgG in the neonatal rat has been reported ( 107 , 108 ) and an increased permeability of tight junctions may permit the passage of larger peptides. Bloch et al ( 109 ) demonstrated that 125 I-labelled polypeptide fragments (6–20 kDa) from a pepsin digestion of bovine serum albumin were transferred from the mucosal to the serosal surface of the enterocytes when infused into everted jejunual gut sacs of rats. In subsequent in vivo studies they found that nanogram amounts of unlabelled immunoreactive fragments were detected by RIA of mesenteric and portal venous blood following their infusion into the jejunum.…”

Section: Evidence For the Absorption Of Peptides From The Healthy Gutmentioning

confidence: 99%

Are intact peptides absorbed from the healthy gut in the adult human?

2014

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For over 100 years it was believed that dietary protein must be completely hydrolysed before its constituent amino acids could be absorbed via specific amino acid transport systems. It is now known that the uptake of di- and tripeptides into the enterocyte is considerable, being transported across the intestinal endothelium by the PepT1 H+/peptide co-transporter. There is also evidence that some di- and tripeptides may survive cytosolic hydrolysis and be transported intact across the basolateral membrane. However, other than antigen sampling, the transport of larger intact macromolecules across the intestinal endothelium of the healthy adult human remains a controversial issue as there is little unequivocal in vivo evidence to support this postulation. The aim of the present review was to critically evaluate the scientific evidence that peptides/proteins are absorbed by healthy intestinal epithelia and pass intact into the hepatic portal system. The question of the absorption of oliogopeptides is paramount to the emerging science of food-derived bioactive peptides, their mode of action and physiological effects. Overall, we conclude that there is little unequivocal evidence that dietary bioactive peptides, other than di- and tripeptides, can cross the gut wall intact and enter the hepatic portal system in physiologically relevant concentrations.

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Section: Evidence For the Absorption Of Peptides From The Healthy Gutmentioning

confidence: 99%

Are intact peptides absorbed from the healthy gut in the adult human?

2014

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“…However, the presence of circulating anti-gliadin antibody had little effect on the amounts of radiolabclled gliadin re covered from the serum or tissues after feeding. It has been shown previously that despite crossing the mucosa [19,20], intact dietary antigens and polypeptide fragments thereof are cleared within 18-22 h from the circulation [20]. Our data suggest that specific IgG antibody has little overall effect on this process.…”

Section: Discussionmentioning

confidence: 46%

Specific Circulating Anti-Gliadin IgG-Class Antibody Does Not Mediate Intestinal Enteropathy in Gliadin-Fed Mice

Smart

Trejdosiewicz²,

Howdle³

1992

Int Arch Allergy Immunol

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The effects of specific circulating IgG antibody on the uptake of dietary antigen and in the generation of intestinal enteropathy have been investigated in Balb/c mice bred on a gluten-free diet. A monoclonal IgG1 antibody (GD3) was prepared against gliadin. After adoptive transfer into mice, this antibody was capable of mediating a type III hypersensitivity response in vivo to footpad challenge with gliadin. The titres of circulating GD3, as estimated in vitro by ELISA, correlated well with the degree of inflammation at sites of type III responses in vivo. Following footpad challenge with gliadin, titres of circulating GD3 antibody were reduced. GD3 antibody was tested for its ability to mediate inflammatory responses in vivo in the intestinal mucosa of mice fed with gliadin. Circulating GD3 antibody was removed selectively and specifically by dietary gliadin, compared to feeding with bovine serum albumin or maintenance on a gliadin-free diet only. However, we were unable to demonstrate any pathological changes in the intestine as a result of possible local antigen-antibody complex formation or deposition. Using radio-iodinated gliadin as a trace marker, no significant retention of gliadin in the intestinal mucosa was found in mice pre-injected with GD3 antibody. These data suggest that circulating IgG antibody has little effect on dietary antigen uptake in the gut, and alone is insufficient to mediate an enteropathy.

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“…Diffe rent approache s have be en re porte d to study BBM± prote in interactions and to characte rize deve lopme ntal change s in BBM structure . Be side histochemical studie s (23,24) and utilization of isolate d enterocyte s (25) and of gut sacs (3,13,26,27) , BBM vesicle s have bee n use d. As the smalle st unit for studying membrane structure and function (28) , BBM vesicle s allow description of e nte rocytic binding structure s in detail, at the same time reducing the complexity of the inve stigate d syste m. Binding characte ristics of rat BBM ve sicle s for food prote ins and le ctins have bee n asse ssed in centrifugation and ® ltration binding assays (14, 16, 29 ± 33) . A conside rable drawback of the se methods was the ir low sensitivity in de tecting weak food prote in binding.…”

Section: Discussionmentioning

confidence: 99%

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Bolte¹,

Knauss²,

Metzdorf³

et al. 1998

Digestive Diseases and Sciences

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To investigate maturational changes of membrane food protein binding capacity, we studied binding characteristics of brush border membranes isolated from small intestines of newborn and adult rats. Binding of biotinylated gliadin peptides, cow's milk proteins (alpha-casein, beta-lactoglobulin, alpha-lactalbumin, bovine serum albumin) and lectins was assessed by a sensitive chemiluminescence blot assay. We found specific food protein binding with regard to saturation and inhibition. Maximal binding of most food proteins and several lectins to brush border membranes of newborn and adult rats was comparable, whereas binding of beta-lactoglobulin was substantially less. Common or adjoining binding sites for the different food proteins tested were indicated by corresponding membrane protein binding patterns and by inhibition properties of unrelated proteins. Compared to newborns, adult membrane vesicles as well as isolated membrane proteins showed higher binding capacities. Thus postnatal maturation of small intestinal brush border membranes correlated with increased food protein binding capacity.

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Uptake of polypeptide fragments of proteins by rat intestine in vitro and in vivo

Cited by 15 publications

References 15 publications

Are intact peptides absorbed from the healthy gut in the adult human?

Are intact peptides absorbed from the healthy gut in the adult human?

Specific Circulating Anti-Gliadin IgG-Class Antibody Does Not Mediate Intestinal Enteropathy in Gliadin-Fed Mice

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