Association of Bacteroides acidifaciens relative abundance with high-fibre diet-associated radiosensitisation

Abstract

BackgroundPatients with pelvic malignancies often receive radiosensitising chemotherapy with radiotherapy to improve survival, however this is at the expense of increased normal tissue toxicity, particularly in elderly patients. Here we explore if an alternative, low-cost and non-toxic approach can achieve radiosensitisation in mice transplanted with human bladder cancer cells. Other investigators have shown slower growth of transplanted tumours in mice fed high-fibre diets. We hypothesised that mice fed a high-fibre diet would have improved tumour control following ionising radiation (IR) and that this would be mediated through the gut microbiota.ResultsWe investigated the effects of four different diets (low fibre, soluble high fibre, insoluble high fibre and mixed soluble/insoluble high fibre diets) on tumour growth in immunodeficient mice implanted with human bladder cancer flank xenografts and treated with ionising radiation, simultaneously investigating the composition of their gut microbiomes by 16S rRNA sequencing. A significantly higher relative abundance of Bacteroides acidifaciens was seen in the gut (faecal) microbiome of the soluble high fibre group, and the soluble high fibre diet resulted in delayed tumour growth after irradiation compared to the other groups. Within the soluble high fibre group, responders to irradiation had significantly higher abundance of B. acidifaciens than non-responders. When all mice fed with different diets were pooled, an association was found between the survival time of mice and relative abundance of B. acidifaciens. The gut microbiome in responders was predicted to be enriched for carbohydrate metabolism pathways and in vitro experiments on the transplanted human bladder cancer cell line suggested a role for microbial-generated short-chain fatty acids and/or other metabolites in the enhanced radiosensitivity of the tumour cells.ConclusionsSoluble high fibre diets sensitised tumour xenografts to irradiation and this phenotype was associated with modification of the microbiome and positively correlated with B. acidifaciens abundance. Our findings might be exploitable for improving radiotherapy response in human patients.

A potential probiotic- Lachnospiraceae NK4A136 group: Evidence from the restoration of the dietary pattern from a high-fat diet

“…7 and 8d). Bacteriodes acidifaciens has been reported that it prevents obesity and improves insulin sensitivity [32] and its abundance elevates in the high ber dietary [31,48]. In our study, CD dietary contained 5.3 % crude ber, 15.4 % neutral detergent ber, and 6.3 % acid detergent ber.…”

“…The short-chain fatty acid (SCFA)producing bacteria such as Lachnospira, Akkermannsia, Bi dobacterium, Lactobacillus, Ruminococcus, Roseburia, Clostridium, Faecalibacterium, and Dorea was a signi cant decrease in human receiving low ber diet [29,30].. In addition, intestinal Bacteroides acidifaciens were increases in mice fed a high ber diet [31] and played a role in obesity prevention and improves insulin sensitivity in mice [32]. Notably, HFD has also been linked to enhanced tumorigenicity of colonocytes [33,34].…”

The role of dietary supplements, including biotics, glutamine, polyunsaturated fatty acids and polyphenols, in reducing gastrointestinal side effects in patients undergoing pelvic radiotherapy: A systematic review and meta-analysis

“…Preclinical studies have shown that prebiotics can enhance the efficacy of chemotherapy and radiotherapy [42,43], in terms of tumour control. As most modern neoadjuvant/radical pelvic radiotherapy regimens (except prostate cancer) include chemotherapy, and with the current interest in combined brachy-EBRT dose-escalation in prostate cancer, the future clinical applicability of biotics in clinical practice should be rigorously evaluated in terms of both tumour control and sparing of normal tissue toxicities in these modern settings.…”

Undaria pinnatifida improves obesity-related outcomes in association with gut microbiota and metabolomics modulation in high-fat diet-fed mice

“…Growing evidence indicates that gut microbiota contributes to keeping homeostasis of host metabolism (Peron et al 2020;Rooks and Garrett 2016). Previous studies reported that gut microbiota regulation using dietary fibers exerts beneficial effects on host health (Then et al 2020) and alleviates obesity-related metabolic diseases (Wang et al 2020). Makki et al (2018) reviewed the effect of dietary fiber on gut microbiota in host health and several diseases.…”