Periodic Reporting for period 1 - MECoCaM (Human gut Microbiome, gene Expression and Colorectal Cancer: Assigning causal roles from a novel Mendelian randomization perspective.)
Période du rapport: 2018-09-03 au 2020-09-02
Colorectal cancer (CRC) is the fourth leading cause of cancer-related deaths in the world and its burden is expected to increase by 60% to more than 1.1 million cancer deaths by 2030. Among CRC risk factors, the contribution of the microbial ecosystem in the gut (gut microbiome) to CRC is not well understood. Some correlations between a microbe and cancer stages have been observed, but only Fusobacterium has shown consistent evidence as risk factor. Additionally, the enrichment of a microbe at a tumour site does not directly assume causation. Rather, microbes may find a carcinogenic ambient as underused nutritional niche (reverse causation) or external exposures can be independently influencing both microbial and host cell proliferation (confounding).
In order to reveal causal associations between microbiota and CRC risk and its biological mechanism, in this project, we assessed the potential causal effect of microbiota on host colon gene expression and on CRC risk, using genetic instruments under a Mendelian randomization approach.
The results did not clarify the role of microbiota to CRC risk; however, their reflected the effect of the gut microbiota composition in the gene expression of a healthy colon tissue. This can be used as a reference dataset for microbiome-based therapies in colon diseases, such as CRC and inflammatory bowel diseases.
In order to reveal causal associations between microbiota and CRC risk and its biological mechanism, in this project, we assessed the potential causal effect of microbiota on host colon gene expression and on CRC risk, using genetic instruments under a Mendelian randomization approach.
The results did not clarify the role of microbiota to CRC risk; however, their reflected the effect of the gut microbiota composition in the gene expression of a healthy colon tissue. This can be used as a reference dataset for microbiome-based therapies in colon diseases, such as CRC and inflammatory bowel diseases.
Initially, using genetic instruments for gut microbiota from The Flemish Gut Flora Project (FGFP), we identified weak association between microbiome taxa and CRC risk, and we could not appraise the role of microbiota to CRC risk. This was done in collaboration with Prof. Nicholas Timpson from the School of Social and Community Medicine of the University of Bristol in UK.
Analysing 350 gut healthy tissue samples we identified 15,542 genes expressed in the gut that clustered in 22 modules of gene co-expression (correlated gene expression). Then, during the secondment performed at the APC Microbiome Institute at the University of Cork under the supervision of Prof. Paul O’Toole, we distinguished 245 different bacterial taxa, most of them clustered in 28 modules of co-abundance (correlated taxa), and 14 of these clusters influenced the gene expression of 17 modules of gene co-expression.
The methodology and results were disseminated in international conferences as poster or oral presentations for the scientific audience, and as videos at the IDIBELL Youtube channel for the general audience. Scientific publications will be ready by 2021.
Analysing 350 gut healthy tissue samples we identified 15,542 genes expressed in the gut that clustered in 22 modules of gene co-expression (correlated gene expression). Then, during the secondment performed at the APC Microbiome Institute at the University of Cork under the supervision of Prof. Paul O’Toole, we distinguished 245 different bacterial taxa, most of them clustered in 28 modules of co-abundance (correlated taxa), and 14 of these clusters influenced the gene expression of 17 modules of gene co-expression.
The methodology and results were disseminated in international conferences as poster or oral presentations for the scientific audience, and as videos at the IDIBELL Youtube channel for the general audience. Scientific publications will be ready by 2021.
We described for first time the effect of the gut microbiota composition in the gene expression of a healthy colon tissue, and generated a reference dataset for microbiome-based therapies in colon diseases, such as CRC and inflammatory bowel diseases. These results are paving the way to guide a state-of-art multidisciplinary approach to the microbiome-based therapies, a research field with great success in the following decade.