Association between gut microbiome and T lymphocytes among different primary tumor sites of patients with metastatic colorectal cancer.

Abstract

e16013 Background: Different primary tumor sites could impact colorectal cancer (CRC)’s survival outcomes and treatment effects. Previous studies had found that gut micro-biome distributions were different between left and right colon cancer(LCC, RCC). Out study aimed to further investigate the association between micro-biome and T lymphocytes among different tumor sites of patients with metastatic CRC. Methods: Between April 2018 and Mars 2019, we enrolled 40 metastatic CRC patients in Xiyuan Hospital of China Academy of Chinese Medical Sciences, Beijing, China. We collected patients’ stool samples for micro-biome analysis by 16s rRNA sequencing approaches, as well as patients’ blood samples to analyses T lymphocyte subsets by flow cytometry methods. The study had been proved by ethics committee of Xiyuan Hospital (2016XLA122-1). All patients consented before enrollment. Results: Among 40 patients, 28% were female, with average age of 63±15 years old. There were 10 RCC, 9 LCC and 21 rectal cancer(RC) patients. Alpha diversity analysis showed that sobs index of the micro-biome of patients with RC and RC was significantly higher than whom were RCC(254.89±99, 247±89 versus.[vs.]101.17±51, p= 0.001). PCoA analysis on OTU level detected that first principal component[PC1] (26.24%) could be separated significantly between RCC and LCC( p= 0.048), as well as between RC and RCC (PC1,14.17%, p= 0.024). Community analysis showed that the proportion of Bacteroidetes was significantly higher in patients with RCC than whom with LCC and RC( p= 0.009). Conversely, the proportion of Firmicutes, Proteobacteria and Verrucomicrobia were higher in LCC patients than others( p= 0.37, 0.047 and 0.032 respectively). Canonical Correlation Analysis (CCA) analysis proved that the CD4+ and CD8+ T cells counts were environmental factors, which were significantly associated with certain micro-biome and samples from different tumor sites( p= 0.037 and 0.01 respectively). Trends showed that CD4+ T cells were positively related with samples of RC and bacteria parabacteroides and bifidobacterium, while CD8+ T cells were positively related with samples of RCC and bacteria Lachnospira, Sutterella and Bacteroides. Conclusions: In our study, we found that patients with LCC and RC had more beneficial gut micro-biome than whom with RCC. In addition, such difference might be associated with body T cell immunity.