Experimental Studies On The Effects Of Deoxynivalenol On Immunological Function In Vitro And In Vivo

Objectives: Trichothecene mycotoxin is a group of structurally similar fungal secondary metabolites that are capable of producing a wide range of toxic effects. Deoxynivalenol (DON, vomitoxin), a most commonly seen trichothecene mycotoxins mainly produced by some Fusarium fungi, is the deoxyderivative of nivalenol. DON contamination of grains is a very common phenomenon worldwidely. DON is one of the predominating contaminating mycotoxins in the grains and foodstuffs in the high incidence area of esophageal cancer in China. Previous studies showed that DON could inhibit synthesis of biological macromolecules in animals and have some negative effects on immune system. Nevertheless, there are still some problems and doubts need to be further elucidated. Most previous experiments on immunotoxic effects of DON were carried out in vitro and mainly involved cytokine secretion. Few works on how to preclude immunotoxic effects of DON were carried out. It is known to all that immune system is a very complex biological system, including complement system, cytokine secretion, adhesion molecule, apoptosis and proliferation of immune cells and processing and transport of antigen. Therefore, to completely evaluate immunotoxic effects of DON, it is very important and necessary to further explore the effects of DON on apoptosis and proliferation of immune cells and processing and transport of antigen and how to how to preclude immunotoxic effects of DON. To further elucidate the effects of DON on immunological function in vitro and in vivo and explore the putative effects of DON exposure on the carcinogenesis of esophageal cancer in the high incidence area, the following studies were carried out:1. Effects of deoxynivalenol at different concentrations on apoptosis and proliferation of mouse thymocytes in vivo were studied with animal experiment, electron microscoPIc observation, DNA agarose gel electrophoresis and flow cytometric analyses.2. Effects of riboflavin and ascorbic acid on the apoptosis and proliferation inhibition of thymocytes induced by DON in KM mice were studied with animal experiment, DNA agarose gel electrophoresis and flow cytometric DNA content analysis.3. The effects of DON at different concentrations on HLA-Ⅰexpression of human peripheral blood mononuclear cells in vitra at protein level were studied with flow cytometric analyses and western blotting.4. TAP-1 and LMP-2　expression of human peripheral blood mononuclear cells treated with DON at different concentrations were studied with reverse transcription-polymerase chain reaction(RT-PCR) and flow cytometric analysis.Methods: 1 Determination of apoptosis and proliferation of thymocytes in KM mice treated with DON in vivo 48 KM mice were randomLy divided into 6 groups: control group, DON 0.5mg/kg, 1mg/kg, 2mg/kg, 4mg/kg and 8mg/kg group. Eight mice in each group. The mice were respectively treated with saline and different concentration DON solutions by intraperitoneal injection. All mice were killed by exsanguinations from femoral artery, 12h after intraperitoneal injection. Fresh thymus specimens were prepared for FCM single cell suspension, DNA abstraction and election microscoPIc specimen. The apoptosis and proliferation of mouse thymocytes treated with deoxynivalenol at different concentrations were determined with electron microscoPIc observation, DNA agarose gel electrophoresis and flow cytometric analyses.2 Determination of thymocytes apoptosis and proliferation inhibition induced by DON after riboflavin and ascorbic acidpretreatment in KM mice in vivo 118 KM mice were randomLy divided into 14 groups: control group, DON (4mg/kg) group, riboflavin (1.25mg/kg and 10mg/kg) groups, ascorbic acid (25mg/kg and 100mg/kg) groups, riboflavin pretreatment (1.25mg/kg, 2.5mg/kg, 5.0mg/kg and 10.0mg/kg)+DON (4mg/kg) groups, ascorbic acid pretreatment (25mg/kg, 50mg/kg, 75mg/kg and 100mg/kg) +DON (4mg/kg) groups, 8 mice in each group. The mice in riboflavin groups, ascorbic acid groups, riboflavin pretre...