High-fat diet-induced dysbiosis mediates MCP-1/CCR2 axis-dependent M2 macrophage polarization and promotes intestinal adenoma-adenocarcinoma sequence.

High-fat diet (HFD) is a well-known risk factor for gut microbiota dysbiosis and colorectal cancer (CRC). However, evidence relating HFD, gut microbiota and carcinogenesis is limited. Our study aimed to demonstrate that HFD-induced gut dysbiosis promoted intestinal adenoma-adenocarcinoma sequence. In clinical study, we found that HFD increased the incidence of advanced colorectal neoplasia (AN). The expression of monocyte chemoattractant protein 1 (MCP-1), CC chemokine receptor 2 (CCR2) and CD163 in CRC patients with HFD was significantly higher than that in CRC patients with normal diet. When it comes to the Apc mice, HFD consumption could induce gut dysbiosis and promote intestinal carcinogenesis, accompanying with activation of MCP-1/CCR2 axis that recruited and polarized M2 tumour-associated macrophages. Interestingly, transfer of faecal microbiota from HFD-fed mice to another batch of Apc mice in the absence of HFD could also enhance carcinogenesis without significant body weight gain and induced MCP-1/CCR2 axis activation. HFD-induced dysbiosis could also be transmitted. Meanwhile, antibiotics cocktail treatment was sufficient to inhibit HFD-induced carcinogenesis, indicating the vital role of dysbiosis in cancer development. Conclusively, these data indicated that HFD-induced dysbiosis accelerated intestinal adenoma-adenocarcinoma sequence through activation of MCP-1/CCR2 axis, which would provide new insight into better understanding of the mechanisms and prevention for HFD-related CRC.