Abstract:

Objective To investigate the effect and mechanism of Shewanella algae（S.algae）and its specific lipopolysaccharide（LPS）on colorectal adenoma（CRA）. Methods Twenty⁃four female C57BL/6J mice were divided into four groups：the control group，the AOM/DSS group，the AOM/DSS+LPS group，and the AOM/ DSS+S.algae group. qRT⁃PCR and immunohistochemistry（IHC）were used to detect the level of macrophages and the proliferation and cycle of tumor cells in mice. qRT⁃PCR and ELISA were used to evaluate the change of tumor inflammatory microenvironment. The expression of the TLR4/NF ⁃ κB pathway proteins in mice was detected by Western Blot. In vitro experiments were conducted to verify the effects of M1 macrophages and S.algae specific LPS on the proliferation，migration and cycle of colorectal tumor cells. Results Compared with the AOM/DSS group， the degree of atypical hyperplasia of intestinal epithelial cells and the level of M1 macrophage increased，the expression of cell proliferation，cyclin and proinflammatory factor also increased，and TLR4/NF ⁃κB pathway was activated after S.algae and its LPS intervention. In vitro studies have also shown that S.algae and its LPS can promote the proliferation，migration and cycle of colorectal tumor cells. Conclusions S.algae specific LPS may promote the occurrence and development of colorectal adenoma through M1 macrophages.

Key words:

colorectal adenoma, shewanella algae, lipopolysaccharide, macrophages