Molecular Mechanisms Of CXCL17 And Its Mimetic Peptides To Relieve Intestinal Mycotoxin Injury

Mycotoxins are toxic compounds and secondary metabolites produced by fungi or molds.They are also frequently contacted by human beings and other animals in the daily diet process.With the acceleration of people’s life rhythm and rich diet,more and more potential mycotoxins enter the digestive tract system through the food chain.The mycotoxins can cause diarrhea,enteritis,even gastrointestinal cancer,and other diseases.Chemokine CXCL17 is highly expressed in gastrointestinal tissues.It had been identification recently.CXCL17 can inhibit intestinal inflammation and maintain the stability of the gastrointestinal immune system.In order to treat the toxic damage of mycotoxins on the human gastrointestinal tract,this study analyzed the function and mechanism of CXCL17 on relieving the toxin damage of mycotoxins in the gastrointestinal tract.And we also explored potential new therapeutic drugs in order to further improve diet safety and protect human health.The activation and protection mechanism of CXCL17 protein on toxin damage to intestinal tract caused by food-borne mycotoxins were investigated for the first time.Seven common food-borne mycotoxins were studying in this research,including Ochratoxin A,T-2 toxin,Fumonisin B1,Aflatoxin B1,Deoxynivalenol,Patulin and Zearalenone.Otherwise,two novel polypeptide drug molecules,CX1 and CX2,were also designed by computer-aided design technology based on the binding action of CXCL17 and CXCL17 receptor GRP35.All the biological activities of mimetic peptides were also study in this paper.In this study,it found that mycotoxins could promote the expression of CXCL17 after acting on intestinal epithelial cells.Mycotoxin could induce intestinal epithelial cells,Caco-2,to produce ROS molecules through dose and time effects.CXCL17 expression was induced by different doses of mycotoxins.However,this expression trend was reversed by ROS inhibitors and P38 and JNK pathway inhibitors.The above results showed that CXCL17 was correlated with mycotoxins in intestinal epithelial cells.By constructing the over-expression system and silencing system of CXCL17,the effects of CXCL17 on the expression of inflammatory cytokines(IL-6 and TNF-α)and apoptosis damage signal,including caspase-3/7 activity,Bcl-2/Bax expression level,mitochondrial membrane potential,PI dye membrane permeability,and tight junction protein expression level,caused by mycotoxins were discussed.The results showed that overexpression of CXCL17 could effectively alleviate the m RNA and protein levels of IL-6 and TNF-α induced by mycotoxins,while downregulation of CXCL17 can increase the expression level of the above inflammatory factors.Over-expression of CXCL17 could also effectively reduce caspase-3/7 activity,Bcl-2/Bax expression level,and mitochondrial membrane potential.It could also effectively reduce cell membrane damage.However,the downregulation of CXCL17 did not significantly alleviate the apoptosis injury.The results showed that CXCL17 had an important protective effect on intestinal damage caused by mycotoxins.The expression levels of PI3K/AKT and mTOR signal pathways were analyzed by Western blotting.The results showed that the above two signal pathways could be effectively activated after overexpression of CXCL17.The signal pathway inhibitors LY294002 and Rapamycin could effectively inhibit the anti-inflammatory and anti-apoptosis effects of CXCL17.Therefore,PI3K/mTOR signaling pathway played a key role in the protection and regulation of CXCL17.Furthermore,two CXCL17 mimetic peptides,CX1 and CX2,were designed and verified by computer-aided design technology.With the help of supercomputing server,after analyzing the interaction model between CXCL17 and GPR35,the mimetic peptides,CX1 and CX2,were screened from the mimetic peptide library of CXCL17.The biological toxicity of CX1 and CX2 and their recognition with GPR35 or Caco-2 cells were analyzed.The results showed that CX1 and CX2 could effectively bind to GPR35 receptor and Caco-2 cell membrane,but cytotoxicity would occur over 320 μM.In addition,the reversal effects of CX1 and CX2 on intestinal inflammation and apoptosis induced by mycotoxins were also verified.Combining the above results,CX1 and CX2 were effective CXCL17 mimetic peptides.In recent years,with the development of science and technology and the enhancement of human attention to diet health,the damage of mycotoxins to the digestive system has gradually become a research hotspot.This study was the first in-depth study on the protective effect of intestinal chemokine CXCL17 on mycotoxin intestinal injury and its related mechanisms.At the same time,two CXCL17 mimetic peptides CX1 and CX2 were designed and verified for the first time,which laid a solid foundation for further development of mycotoxin intestinal injury protection drugs.