Faeces from malnourished colorectal cancer patients accelerate cancer progression

Backgroud: Malnutrition has been confirmed to play an important role in colorectal cancer (CRC) progression via the gut microenvironment. However, the characteristics of the gut microbiota or its potential biological mechanism in CRC remain inconclusive. Methods: In this work, Patient-Generated Subjective Global Assessment (PG-SGA) tool and 16sRNA sequencing were prepared to detect the variation in gut microbiota and the association between nutrition status and gut microbiota. RDA/CCA analysis was used to evaluate the relationship between faecal microbiota from malnourished CRC and clinical nutrition indicators. To investigate the mechanism of the gut microbiota in CRC, faecal samples from malnourished CRC patients were transplanted into C57BL/6J and DSS/AOM mouse models. Moreover, FACS and IHC were prepared to detect the infiltration of B cells and macrophages. qPCR and Elisa assays were performed to explore the expression of cytokines. Result: We found dramatic variation in the faecal microbiota among patients with different nutritional statuses, discovering that specific microbiota species, namely, Atopobium vaginae, Selenomonas sputigena and Faecalibacterium prausnitzii, may be considered diagnostic biomarkers in malnutrition and indicate poor prognosis. High expression level of A. vaginae in CRC tissues revealed the poorer overall survival compared with low expression level (Mean survival: 23.0 months vs 29.0 months). Faecal from malnourished colorectal cancer were found to be protumorigenic. More importantly, our evidence suggests that after faecal microbiota transplantation, B cells and macrophages are recruited to activate specific tumour immunity in CRC. Depletion of B cells significantly suppressed faecal microbiota-induced M2b polarization as well as the protumorigenic activity of tumour-associated macrophages in vivo. Conclusion: Faecal microbiota in CRC under malnutrition conditions exhibits specific characteristics that accelerate CRC progression and regulate B cells and macrophages. The use of specific faecal microbial species could be a feasible approach for identifying the malnutrition status of patients and demonstrating the poor prognosis of CRC. (c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study investigates the role of gut microbiota in colorectal cancer (CRC) under malnutrition conditions. The researchers found significant variations in the gut microbiota among patients with different nutritional statuses. Specific microbiota species were identified as potential diagnostic biomarkers for malnutrition and indicators of poor prognosis in CRC. Furthermore, the study demonstrated that after fecal microbiota transplantation, B cells and macrophages were recruited to activate specific tumor immunity in CRC. These findings highlight the importance of gut microbiota in CRC progression and its potential as a diagnostic tool.