The Effect of Inflammation on Microbiota Composition in Colorectal Cancer

Sammanfattning

Dysbiosis, an imbalance in the gut microbiota, has been associated with the development of colorectal cancer (CRC). This study aims to contribute to the understanding of this potential correlation by analysing the diversity and composition of the colonic microbiota in untreated mice and mice treated with AOM/DSS, which are known to induce CRC. The study also aims to investigate differences in microbiota diversity and composition between the sexes. Already sequenced genetic data were examined using various statistical methods. Alpha diversity analysis was done to measure the variety of present species within the groups that the mice were divided into. Beta diversity analysis was done to determine how different the groups of mice were in comparison to each other with regard to their species content. Three methods for differential abundance analysis (DAA) were applied to identify differences in abundance of specific bacterial species between the study groups. The alpha diversity analysis did not indicate any significant differences in diversity between any groups. On the other hand, the beta diversity analysis showed significant differences in diversity between treated and untreated mice, specifically between treated and untreated females. The results of the beta diversity analysis are consistent with the DAA which resulted in differentially abundant species for the same comparisons. In the DAA, the species Muribaculumsp002492595 and species belonging to the anti-oncogenic bacterial family Lachnospiraceae was found to be more abundant in untreated mice, while the genus Bacteroides was more abundant in treated mice. The results of the study, that is, the differences in microbial diversity between treated and untreated mice and the specific differentially abundant species that were found, are important for further research and the long-term goal of using the microbiota to develop novel diagnostics and treatments for CRC.