Toxicity of Wheat Flour Proteins and Protein-Derived Peptides for In Vitro Developing Intestine from Rat Fetus

Abstract

A peptic-tryptic-cotazym (PTC) digest of a crude wheat gliadin preparation was obtained under experimental conditions simulating in vivo protein digestion and then fractionated into 10 peaks by ion-exchange chromatography. PTC-gliadin digest and one of its subfractions (coded as fraction 9 according to its elution pattern) were very active in inhibiting in vitro development and morphogenesis of small intestine from 17- and 18-day-old rat fetuses, whereas they were harmless for the culture of jejunum from 21-day-old fetuses. PTC-digest also induced extensive tissue degeneration and necrosis of in vitro cultured small intestinal mucosa from patients with active celiac disease (gluten-induced entheropathy), but did not cause any detectable effect on histologically normal human small intestinal mucosa. Some wheat albumin and gliadin fractions were also tested on in vitro developing small intestine from 17-day-old rat fetus. Among all the tested protein fractions, only one gliadin fraction (coded as alpha 10-gliadin from its gel electrophoretic mobility) exhibited a toxic effect; morphologic alterations induced by alpha 10-gliadin were similar to those induced by PTC-digest and fraction 9.

Intestinal Mucosa of Celiacs in Remission Is Unable To Abolish Toxicity of Gliadin Peptides on in Vitro Developing Fetal Rat Intestine And Cultured Atrophic Celiac Mucosa

“…The other fractions tested were less active or not active in these in vitro systems. The results therefore confirm previously published findings (22,24). The activity of gliadin peptides in the various in vitro systems we use appears to be in some way related to the in vivo toxicity in celiac disease, as the same fractions 9 and 2R have been shown to contain a large proportion of gliadin peptides that are toxic in vivo to celiac patients.…”

“…Sephadex. Fraction 9 of this digest is the most active in causing significant reduction in D-xylose absorption in celiac patients in remission (25), preventing the morphological recovery of the epithelium of the atrophic intestinal mucosa of celiac patients (26) and inhibiting the in vitro development and differentiation of the fetal rat intestine (22).…”

“…Gliadin and prolamin peptides from cereals that are toxic in celiac disease (wheat, rye, barley, and oats) are very active in inhibiting in vitro development and morphogenesis of small intestine from 17-day-old rat fetuses (22,23).…”

Early tissue transglutaminase–mediated response underlies K562(S)-cell gliadin-dependent agglutination

“…Alijet were obtained as previously described (8). Peptides α-9 (spanning position 57-68 of α-gliadin) and 31-43 were synthesized using fluorenylmethyloxycarbonyl (Fmoc) chemistry by Primm (Milan, Italy) (6,16).…”

“…These studies have suggested that different portion(s) of gliadin, ostensibly not the ones recognized by T cells, modulate an innate activation of celiac small intestine that sets the tone and intensity of the adaptive immune response induced by the immunodominant gliadin epitopes (6). Surprisingly, gliadin and prolamin preparations also show biological activity on celiac-unrelated in vitro systems, including intestinal epithelial cells lines, fetal rat jejunum, and K562(S) cells, a highly undifferentiated cell line isolated from an outgrowth of a patient with chronic myelogenous leukemia (7)(8)(9). K562(S) cells undergo agglutination within few minutes after contact with gluten digests.…”