Background:Intestinal microbiota dysbiosis and impaired intestinal barrier,leading to bacterial translocation,are involved in acute pancreatitis(AP)exacerbation.Antimicrobial peptides participate in the regulation of intestinal microbiota,yet their changes and roles in the course of AP are unclear.Aims:To investigate the dynamic changes and significance of antimicrobial peptides in the ileum and pancreas among three classical AP models.Methods:Three AP mouse models were established by using cathelicidin plus lipopolysaccharide(CAE+LPS),sodium taurocholate(N-Tau)and L-arginine(L-Arg),respectively.The pathological changes of pancreatic and ileal tissues were observed and scored.Real-time PCR was applied to detect the expression levels of the proinflammatory cytokines,and antimicrobial peptides including lysozyme(LZM),secretory phospholipase A2(sPLA2),angiogenin 4(Ang4),regenerating islet-derived protein 3(REG3)family,β-defensin family,cathelicidin-related antimicrobial peptide(CRAMP),and glycoprotein 2(GP2)in ileum and/or pancreas.The association between expressions of antimicrobial peptides and the injuries of pancreas and ileum was analyzed.Results:Pancreatic and ileal injuries could be observed in all three AP models in different time points with various degrees.The pathological scores of the CAE+LPS and N-Tau models reached the highest level and then declined from 0-72 h,while those of L-Arg model progressively increased within 72 hours.Compared with the corresponding controls,the mRNA levels of LZM,sPLA2,and Ang4 in ileal tissue,and the mRNA levels of CRAMP,GP2,and β-defensins in pancreatic tissue,were generally downregulated in all three AP models(all P<0.05).CAE+LPS and N-Tau models showed a trend of initial decrease followed by partial recovery,while L-Arg model exhibited a gradual downregulation trend.The mRNA levels of REG3β and REG3γ in ileum upregulated and reached the peak at 48 h or 24 h and downregulated significantly at 72 h in all three AP models(all P<0.05);while in pancreatic tissue,both REG3β and REG3γ were generally upregulated in all three AP models(all P<0.05),but fell back in CAE+LPS and N-Tau models at 72 h.The mRNA levels of ileal β-defensins upregulated significantly in the early stage of the disease(12 h)in all three AP models(all P<0.05),and then gradually decreased.Spearman correlation coefficient analysis showed that the expressions of ileal LZM,sPLA2,and Ang4,as well as the pancreatic CRAMP,GP2,and β-defensins,were significantly negatively correlated with the pancreatic and ileal pathological scores in all three AP models(all P<0.05);but the expression of REG3β in the pancreas was significantly positively correlated with the pancreatic and ileal pathological scores(all P<0.05).Conclusions:The expressions of LZM,sPLA2,and Ang4 in the ileum,as well as the expressions of CRAMP,GP2,β-defensin family,and REG3β in the pancreas of the three classical AP models,dynamically changed with the severity of the disease.Ileal and pancreatic antimicrobial peptides may affect the injuries of pancreas and intestine during AP by regulating intestinal microbiota.
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