Effects of Digested Onion Extracts on Intestinal Gene Expression: An Interspecies Comparison Using Different Intestine Models

Abstract

Human intestinal tissue samples are barely accessible to study potential health benefits of nutritional compounds. Numbers of animals used in animal trials, however, need to be minimalized. Therefore, we explored the applicability of in vitro (human Caco-2 cells) and ex vivo intestine models (rat precision cut intestine slices and the pig in-situ small intestinal segment perfusion (SISP) technique) to study the effect of food compounds. In vitro digested yellow (YOd) and white onion extracts (WOd) were used as model food compounds and transcriptomics was applied to obtain more insight into which extent mode of actions depend on the model. The three intestine models shared 9,140 genes which were used to compare the responses to digested onions between the models. Unsupervised clustering analysis showed that genes up- or down-regulated by WOd in human Caco-2 cells and rat intestine slices were similarly regulated by YOd, indicating comparable modes of action for the two onion species. Highly variable responses to onion were found in the pig SISP model. By focussing only on genes with significant differential expression, in combination with a fold change > 1.5, 15 genes showed similar onion-induced expression in human Caco-2 cells and rat intestine slices and 2 overlapping genes were found between the human Caco-2 and pig SISP model. Pathway analyses revealed that mainly processes related to oxidative stress, and especially the Keap1-Nrf2 pathway, were affected by onions in all three models. Our data fit with previous in vivo studies showing that the beneficial effects of onions are mostly linked to their antioxidant properties. Taken together, our data indicate that each of the in vitro and ex vivo intestine models used in this study, taking into account their limitations, can be used to determine modes of action of nutritional compounds and can thereby reduce the number of animals used in conventional nutritional intervention studies.

Lactobacillus acidophilus Attenuates Salmonella-Induced Stress of Epithelial Cells by Modulating Tight-Junction Genes and Cytokine Responses

“…Total RNA was isolated as reported previously ( de Wit et al, 2016 ). Total RNA was quantified with the Nano-drop ® ND-1000 Spectrophotometer (Thermo Scientific, Wilmington, DE, United States) at OD 260 nm and the purity was expressed with OD 260 nm /OD 280 nm .…”

“…RNAs of each independent Caco-2 experiment were hybridized to Affymetrix Human Gene 1.1 ST arrays according to standard Affymetrix protocols as described previously ( de Wit et al, 2016 ). Quality control of the datasets was performed using Bioconductor packages ( Gentleman et al, 2004 ) integrated in an on-line pipeline ( Lin et al, 2011 ).…”

The Influence of Plants from the Alliaceae Family on Morphological Parameters of the Intestine in Atherogenic Rats

“…Research conducted so far on the role of garlic and onions in the prevention and alleviation of the course of diseases and ailments of the digestive tract is apparently insufficient, inconsistent, incomplete, and often contradictory. Moreover, they relate to various forms of garlic and onion use (fresh vegetables, fresh extract, freeze-dried forms, oil, and isolated compounds), supplementation time and dose, and finally various animal research models (e.g., rats [67][68][69][70][71][72][73], mice [74], pigs [75], broilers, and chickens [76][77][78][79]) with induced injuries of the gastrointestinal tract [67,69,71,73,74] or infected with pathogenic microorganisms [74]. In the available literature, no information was found on the effect of the addition of raw Alliaceae plants, administered in an atherogenic diet, on morphological changes in the intestine.…”