PAMP protects intestine from Enterohemorrhagic Escherichia coli infection through destroying cell membrane and inhibiting inflammatory response.

Proadrenomedullin N-terminal 20 peptide (PAMP) is elevated in sepsis, but the function and possible mechanism of PAMP in bacterial infection is elusive. This study is aim to evaluate the role of PAMP in the interaction between the Enterohemorrhagic E. coli (EHEC) and the host barrier. Our results showed that PAMP alleviated the EHEC-induced disruption of goblet cells and mucosal damage in the intestine, increased the expression of occludin in the colon of EHEC-infected mice, and reduced the proinflammatory cytokines level in serum significantly compared with the control group. Meanwhile, lipopolysaccharide (LPS) stimulation could dose-dependently induce the expression of preproADM, the precursor of PAMP, in human intestinal epithelial cell (HIEC) and human umbilical vein endothelial cell (HUVEC). In addition, PAMP inhibited the growth of EHEC O157:H7 and destroyed the inner and outer membrane. At low concentration, PAMP attenuated the EHEC virulence genes including hlyA and eaeA, which was also confirmed from reduced hemolysis to red cells and adhesion to HIEC. These results indicated that EHEC infection would modulate the expression of PAMP in intestinal epithelium or vascular endothelium, and in turn exerted a protective effect in EHEC induced infection by rupturing the bacterial cell membrane and attenuating the bacterial virulence.