The interaction between mycotoxins and bile acids

Fungal toxins are secondary metabolites of fungi. Animals consuming feed containing fungal toxins can cause liver damage, abnormal liver detoxification function, and metabolic disorders of cholesterol and bile acids. Bile acids are converted from cholesterol in the liver through multiple biosynthetic steps, and are of great significance in maintaining the normal function of the liver, gallbladder, and intestines. They are also closely related to the prevention of diseases such as arteriosclerosis and gallstones. In addition, bile acids can alleviate the damage of fungal toxins to the body. The following will discuss the mutual influence between fungal toxins and bile acids.

The effect of mycotoxins on bile acids

Mycotoxins entering the liver will interfere with the metabolism of Very Low Density Lipoprotein (VLDL) and High Density Lipoprotein (HDL), leading to hypercholesterolemia and atherosclerosis. Exposure to mycotoxins leads to a decrease in cholesterol levels and expression of cholesterol biosynthesis genes in the liver, including HMGCS1, FDPS, SOLE, EBP, FDFTI, and VLDLR. When piglets are exposed to toxic levels of aflatoxin AFB1, the expression of genes regulating cholesterol and fatty acid homeostasis (ABC8, SCD1, LDLR, and FASN) changes. In addition, treatment of rats with aflatoxin AFB1 significantly reduced the levels of cholesterol derivatives (cholesterol, cholesterol esters, chenodeoxycholic acid, dihydroxycholesterol, hydroxycholesterol, and 5-cholesterol) involved in the conversion of cholesterol to bile acid in their feces. The bile acids synthesized by the liver enter the small intestine and play a role in promoting lipid digestion and absorption. In the ileum, most bile acids are reabsorbed into the bloodstream and circulate back to the liver through the portal vein. Intestinal inflammation can affect the reabsorption of bile acids and interfere with the enterohepatic circulation of bile acids. DON exposure can disrupt the active transport of bile acids in Caco-2 intestinal epithelial cells and reduce the expression of bile acid transporters OST α, IBABP, and ASBT in the cells. In summary, ingestion of mycotoxins can disrupt the homeostasis of cholesterol and bile acids.

Bile acids affect the metabolism and excretion process of mycotoxins

Fungal toxins are lipophilic, and ingested fungal toxins can bind to lipoproteins and be isolated by cholesterol on the surface of lipoprotein particles. This isolation effect helps reduce the toxicity of fungal toxins to the body. Bile acids combine with other substances in the intestine to form a mixture, which may include mycotoxins. In such a mixture, bile acids can promote the excretion of mycotoxins, reduce their retention time in the body, and thus lower the potential harm of mycotoxins to the body. In addition, bile acids affect the absorption rate and degree of food and toxins in the intestine, which in turn affects the concentration and distribution of mycotoxins in the body. In aquaculture, supplementing bile acids to regulate the level of bile acids in the body can interfere with the absorption process of mycotoxins and reduce their harm to the body. Moreover, bile acids affect the metabolic pathways of mycotoxins, altering the structure and activity of their metabolites, thereby affecting the biological effects of mycotoxins.

Fungal toxins affect the synthesis of cholesterol and bile acids in the liver, disrupt the absorption of bile acids in the intestine, and lead to an imbalance of bile acid homeostasis in the body; Bile acids affect the excretion, absorption, and metabolism of mycotoxins, regulating the concentration and biological effects of toxins in the body, thereby reducing the harm of mycotoxins to organisms. In summary, there are complex and important interactions between mycotoxins and bile acids.

Author: Li Yanwei

Original article: Mechanism of lithocholic acid in alleviating liver damage induced by aflatoxin B1 in piglets

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