Gut commensal Alistipes as a potential pathogenic factor in colorectal cancer

Abstract Although previous research has shown that inflammation is associated with development of colorectal cancer (CRC), questions remain about whether inflammatory factor-secreting bacteria play a crucial role in CRC development. The potential role of gut microbiota in secreting inflammatory factors involved in the development of CRC among Chinese patients was explored in this study. 16S rRNA sequencing was utilized to evaluate the distinct microbial characteristics between patients with CRC and colorectal adenoma. Serum levels of inflammatory factors and the expression level of LRG1 tissue protein were studied. The correlation between gut microbiota and inflammatory signaling was analyzed to explore potential molecular mechanisms of CRC. Compared with the adenoma group, CRC patients exhibit distinct pathologies. Moreover, elevated levels of CEA, erythrocytes and haemoglobin in the blood of CRC patients were found. In addition, CRC patients have significantly higher levels of TNF-α, IL-6, IL-10, LRG1 and TGF-β1 when compared with adenoma patients. Spearman correlation analysis revealed that LRG1 was positively related to IL-6 and TNF-α, respectively. The correlation analysis result of TGF-β1 was consistent with the above. Furthermore, we found that the relative abundance of gut commensal Alistipes was significantly elevated in CRC patients. Moreover, a positive correlation between Alistipes and inflammatory signaling was also found. The results suggest that gut commensal Alistipes is a key bacterium with pro-inflammatory properties in the development of CRC. TNF-α and IL-6 associated with Alistipes might activate LRG1-TGF-β1 signaling which contributed to the pathogenesis of CRC.