IDDF2018-ABS-0149 Manipulation of gut microbiota in in vitro model of colorectal cancer: positive effects of lactobacillus rhamnosus against fusobacterium nucleatum

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Abstract

Background

Colorectal cancer (CRC), a leading cause of morbidity and mortality worldwide, is affecting more than 1.36 million people every year. It is a well-known multifactorial disease, and the aetiology is a complex interaction between genetic, lifestyle and environmental factors. However, there has been a general consensus exists that the composition of the human intestinal microbiota is linked to health status. They mainly play a role in modulating normal gut immune function, and most of them are largely beneficial to human. Fusobacterium nucleatum is an anaerobic oral commensal and a periodontal pathogen associated with a wide spectrum of human diseases. Findings from human and animal models have revealed that fusobacterium nucleatum plays a role in colorectal carcinogenesis by suppressing the immune response of the hosts to tumour. The aim of the present study is to determine the role of a probiotic strain in competing with a selected colorectal cancer pathogen.

Methods

Thus, lactobacillus rhamnosus was investigated in vitro to examine its ability to protect, displace and compete with fusobacterium nucleatum. In this study, three different types of assay (protection assay, displacement assay and competitive assay) were performed using SW480, a colorectal cancer cell line as a host cell. Cell proliferation assay was applied to determine the proliferation rate of the cells by measuring the cell metabolic activity.

Results

In a competitive assay, lactobacillus rhamnosus showed greater ability of adherence to host cells than fusobacterium nucleatum with a ratio of 1400:1. Lactobacillus rhamnosus could significantly decrease the proliferation rate induced by fusobacterium nucleatum in protection assay (p<0.001). In addition, the proliferation rate induced by fusobacterium nucleatum was also decreased up to 48.6% in displacement assay by lactobacillus rhamnosus.

Conclusions

This finding may suggest that lactobacillus rhamnosus could help limiting cell proliferation of the cancerous cells in response to pathogens. In conclusion, lactobacillus rhamnosus has a positive impact in reducing the risk of colorectal cancer and possibly an option for preventive.

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