Preliminary Study On Injury And Molecular Mechanism Of Fumonisin B₁ In Intestinal Tract Of Mice

Fumonisin B₁?Fumonisin B₁,FB₁?is a mycotoxin that can widely contaminate crops and seriously endanger the health of animals through the food chain.FB₁ is closely related to swine pulmonary edema,horse leukoencephalomalacia,poultry diarrhea,liver and kidney damage in various animals,and human esophageal cancer and gastrointestinal diseases.The intestine is not only the main place for the body to digest and absorb nutrients,but also an important defensive organ against harmful substances.However,there are few studies on intestinal damage caused by FB₁,and the molecular mechanism of intestinal damage caused by it is not clear.In this experiment,FB₁ was extracted from fumonisins-containing corn.FB₁ in the extract was detected qualitatively and quantitatively by HPLC-FLD,and FB₁ feed with concentration of 5mg/kg was prepared by using the extract;Eighty male Kunming mice were randomly divided in two groups:control group feeding normal feed and experimental group feeding experimental feed.The tissues of duodenum,ileum,cecum and colon were collected after euthanasia on 21d and 42d.In an attempt to investigate the damage effect of FB₁ on the intestinal tract and its molecular mechanism,the following aspects were studied:Pathological analysis was performed by HE staining.The m RNA expression levels of 7 kinds of inflammatory cytokines,Keap1-Nrf2-HO-1antioxidant signal pathway,11 kinds of CYP450 enzyme system gene and their corresponding xenobiotic nuclear receptors such as aryl hydrocarbon receptor?AHR?,constitutive androstane receptor?CAR?and pregnane X receptor?PXR?were detected by fluorescence quantitative PCR.The protein expression levels of 6 kinds of inflammatory cytokines and xenobiotic nuclear receptors AHR?CAR?PXR were detected by western blot technique.The results were as follows:?1?The concentration of FB₁ in the extract was 351.03165?g/ml.?2?FB₁ destroyed the intestinal mucosal layer structure of mice,causing epithelial cell proliferation,telangiectasia,villus and epithelial shedding,atrophy or necrosis in crypt and inflammatory cell infiltration.?3?In the 21d experimental group,FB₁ up-regulated the m RNA expression of IL-1?in duodenum and ileum,NF-?B,TNF-?,TNF-R1,TNF-R2,COX-2,IL-6 in caecum,NF-?B,TNF-R1,TNF-R2,IL-1?in colon,and the protein expression of TNF-?,IL-1?,IL-10 in duodenum,IL-1?,NF-?Bp65 in ileum,NF-?Bp65,TNF-?,IL-1?,IL-10in caecum,IL-4 in colon.In the 42d experimental group,FB₁ up-regulated the m RNA expression of NF-?B,TNF-R1,TNF-R2,IL-1?in duodenum,TNF-?,IL-6 in ileum,NF-?B,TNF-?,TNF-R2,IL-6,IL-1?in caecum,TNF-R1,IL-1?in colon,and the protein expression of NF-?Bp65,IL-1?,IL-4,IL-10 in duodenum,IL-1?,IL-4 in ileum,NF-?Bp65,IL-4 in caecum,IL-4 in colon.?4?The m RNA expression of duodenal Nrf2,caecal Keap1,ileac and colonic Nrf2,HO-1 in the 21d experimental group were increased by FB₁,and the m RNA expression levels of ileac and caecal Keap1,colonic Nrf2 and HO-1 were increased in the 42d experimental group?5?In the 21d experimental group,FB1 increased the m RNA expression of CYP2b1,CYP2b9,CYP2b10,CYP3 family,CAR,PXR,and CYP1a1 m RNA and AHR protein expression in duodenum;Up-regulated Ileac CYP3a11 and PXR m RNA expression;Rose m RNA expression in colonic CYP2b1,CYP3a11 and PXR.In the 42d experimental group,FB₁ caused the m RNA expression of CYP2b4,CYP2b9,CYP2b10,CYP2e1,CYP2f2,CYP2j5 and CAR to rising,and up-regulated the m RNA expression of CYP1,CYP3 family with the protein expression of AHR,PXR in ileum;Added the m RNA expression of CYP1,CYP2 family,the expression of AHR,CAR protein and m RNA,the m RNA expression of CYP3 family and the protein expression of PXR in cecum?except CYP2b1?;The results showed that FB₁ containing 5mg/kg in feed could cause pathological damage in different intestinal tissues of mice,and the injury involved three molecular mechanisms:affecting the expression level of inflammatory cytokines,causing inflammatory reaction and reducing intestinal immune function;Interfering with the transcriptional level of Keap1-Nrf2-HO-1 antioxidant signaling pathway,reducing antioxidant function and disrupting the balance of intestinal redox state;Inducing Xenobiotic nuclear receptors AHR,CAR,PXR to regulate the expression of CYP450enzyme system...