Exposure to the mycotoxin deoxynivalenol reduces the transport of conjugated bile acids by intestinal Caco-2 cells

Effects of Low and High Doses of Deoxynivalenol on Growth Performance, Blood Biochemistry, Histology, Metabolites, and Microbial Community in Adult Rats

Deoxynivalenol (DON) is a widespread mycotoxin which contaminates several crops, including maize, wheat, and barley. In this study, we investigated the effects of orally administered DON on growth performance, blood biochemistry, histology, the gut microbiome, and metabolism in rats. Six-week-old rats, acclimatized for one week, were subjected to different dietary treatments for 42 days, as follows: CON (control): 0.9% saline; T1: 0.5 ppm DON; T2: 50 ppm DON; and T3: 100 ppm DON. The T3 group had the lowest final body weight (298.5 ± 3.69 g) and average daily gain compared with the control group (338.9 ± 6.43 g, p < 0.05). The feed conversion ratio was highest in the T3 group (4.28 ± 0.28) compared with that in the control group (3.12 ± 0.13, p < 0.05). DON treatment significantly reduced serum levels of creatinine, amylase, urea nitrogen, and alkaline phosphatase, but not alanine aminotransferase. Fibrosis and apoptosis were exacerbated in various tissues with increasing DON concentration. The metabolite profiles of several tissues were significantly different in the DON-treated and control groups. In the cecum, DON treatment increased the abundance of Desulfobacteria, while decreasing that of Firmicutes. Our results indicate that DON levels above the maximum residue limit have serious health consequences for animals.

Antibiotics reduce intestinal bile acid reuptake in an in vitro model system

Enterohepatic circulation of bile acids is a highly efficient process that is important for bile acid homeostasis. The aim of the present study was to characterize the impact of a series of antibiotics (lincomycin, streptomycin, vancomycin and tobramycin) on the intestinal reuptake of conjugated bile acids (TCA, TCDCA, GCA and GCDCA) using a Caco-2 in vitro transwell model system. The results obtained demonstrate that both pre-exposure and co-exposure of the cells to an antibiotic and the bile acids, affected bile acid transport, to an extent that depended on the antibiotic, its concentration and the type of conjugated bile acid tested. Tobramycin, at concentrations in line with dose levels at which this antibiotic induced effects on bile acid homeostasis in vivo, appeared able to inhibit bile acid transport after pre-exposure of the cells, likely resulting from an effect on the expression of bile acid transporters via its effects on protein synthesis at ribosome level. Upon co-exposure of the Caco-2 cells to an antibiotic and the bile acids, all four antibiotics appeared to significantly reduce the transport of especially the conjugated bile acids TCDCA and GCDCA with a potency that decreased in the order vancomycin > tobramycin = streptomycin > lincomycin. The effects observed illustrate the possibility of using a new approach methodology (NAM) to study effects on intestinal bile acid reuptake.

In Vitro Digestion and Intestinal Absorption of Mycotoxins Due to Exposure from Breakfast Cereals: Implications for Children's Health

Breakfast cereals play a crucial role in children's diets, providing essential nutrients that are vital for their growth and development. Children are known to be more susceptible than adults to the harmful effects of food contaminants, with mycotoxins being a common concern in cereals. This study specifically investigated aflatoxin B1 (AFB1), enniatin B (ENNB), and sterigmatocystin (STG), three well-characterized mycotoxins found in cereals. The research aimed to address existing knowledge gaps by comprehensively evaluating the bioaccessibility and intestinal absorption of these three mycotoxins, both individually and in combination, when consumed with breakfast cereals and milk. The in vitro gastrointestinal method revealed patterns in the bioaccessibility of AFB1, ENNB, and STG. Overall, bioaccessibility increased as the food progressed from the stomach to the intestinal compartment, with the exception of ENNB, whose behavior differed depending on the type of milk. The ranking of overall bioaccessibility in different matrices was as follows: digested cereal > cereal with semi-skimmed milk > cereal with lactose-free milk > cereal with soy beverage. Bioaccessibility percentages varied considerably, ranging from 3.1% to 86.2% for AFB1, 1.5% to 59.3% for STG, and 0.6% to 98.2% for ENNB. Overall, the inclusion of milk in the ingested mixture had a greater impact on bioaccessibility compared to consuming the mycotoxins as a single compound or in combination. During intestinal transport, ENNB and STG exhibited the highest absorption rates when ingested together. This study highlights the importance of investigating the combined ingestion and transport of these mycotoxins to comprehensively assess their absorption and potential toxicity in humans, considering their frequent co-occurrence and the possibility of simultaneous exposure.

Complementary transcriptomic and proteomic analyses elucidate the toxicological molecular mechanisms of deoxynivalenol-induced contractile dysfunction in enteric smooth muscle cells

Deoxynivalenol (DON) is one of the frequent Fusarium mycotoxins and poses a serious threat to public health worldwide. DON-induced weight loss is tightly connected with its ability to decrease feed intake by influencing gastrointestinal tract (GIT) motility. Our previous reports indicated that DON interfered with intestinal motility by injuring the contractility of enteric smooth muscle cells (SMC). Here, we further explored the potential mechanisms by employing a complementary method of transcriptomics and proteomics using the porcine enteric smooth muscle cell line (PISMC) as an experimental model. The transcriptomic and proteomic data uncover that the expression of numerous extracellular matrix (ECM) proteins and multiple integrin subunits were downregulated in PISMC under DON exposure, suppressing the ECM-integrin receptor interaction and its mediated signaling. Furthermore, DON treatment could depress actin polymerization, as reflected by the upregulated expression of Rho GTPase-activating proteins and cofilin in PISMC. Meanwhile, the expression levels of downstream contractile apparatus genes were significantly inhibited after challenge with DON. Taken together, the current results suggest that DON inhibits enteric SMC contractility by regulating the ECM-integrin-actin polymerization signaling pathway. Our findings provide novel insights into the potential mechanisms behind the DON toxicological effects in the GIT of humans and animals.

Use of Physiologically Based Kinetic Modeling to Predict Deoxynivalenol Metabolism and Its Role in Intestinal Inflammation and Bile Acid Kinetics in Humans

Current points of departure used to derive health-based guidance values for deoxynivalenol (DON) are based on studies in laboratory animals. Here, an animal-free testing approach was adopted in which a reverse dosimetry physiologically based kinetic (PBK) modeling is used to predict in vivo dose response curves for DON's effects on intestinal pro-inflammatory cytokine secretion and intestinal bile acid reabsorption in humans from concentration-effect relationships for DON in vitro. The calculated doses for inducing a 5% added effect above the background level (ED5) of DON for increasing IL-1β secretion in intestinal tissue and for increasing the amounts in the colon lumen of glycochenodeoxycholic acid (GCDCA) were 246 and 36 μg/kg bw/day, respectively. These in vitro-in silico-derived ED5 values were compared to human dietary DON exposure levels, indicating that the risk of DON's effects on these end points occurring in various human populations cannot be excluded. This in vitro-in silico approach provides a novel testing strategy for hazard and risk assessment without using laboratory animals.