The role of intestinal microbiota in development of irinotecan toxicity and in toxicity reduction through dietary fibres in rats.
CPT-11 is a drug used as chemotherapy for colorectal cancer. CPT-11 causes toxic side-effects in patients. CPT-11 toxicity has been attributed to the activity of intestinal microbiota, however, intestinal microbiota may also have protective effects in CP!-11 chemotherapy. This study aimed to elucidate mechanisms through which microbiota and dietary fibres could modify host health. Rats bearing a Ward colon carcinoma were treated with a two-cycle CPT-11/5-fluorouracil therapy recapitulating clinical therapy of colorectal cancer. Animals were fed with a semi-purified diet or a semi-purified diet was supplemented with non-digestible carbohydrates (isomalto-oligosaccharides, resistant starch, fructo-oligosaccharides, or inulin) in 3 independent experiments. Changes in intestinal microbiota, bacteria translocating to mesenteric lymphnodes, cecal GUD activity, and cecal SCFA production, and the intestinal concentration of CPT-11 and its metabolites were analysed. Non-digestible carbohydrates significantly influenced feed intake, body weight and other indicators of animal health. The identification of translocating bacteria and their quantification in cecal microbiota indicated that overgrowth of the intestine by opportunistic pathogens was not a major contributor to CPT-11 toxicity. Remarkably, fecal GUD activity positively correlated to body weight and feed intake but negatively correlated to cecal SN-38 concentrations and IL1-β. The reduction in CPT-11 toxicity by non-digestible carbohydrates did not correlate to stimulation of specific bacterial taxa. However, cecal butyrate concentrations and feed intake were highly correlated. The protective role of intestinal butyrate production was substantiated by a positive correlation of the host expression of MCT1 (monocarboxylate transporter 1) with body weight as well as a positive correlation of the abundance of bacterial butyryl-CoA gene with cecal butyrate concentrations. These correlations support the interpretation that the influence of dietary fibre on CPT-11 toxicity is partially mediated by an increased cecal production of butyrate.
University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada.
Xiaoxi B
XB
Lin
University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada ; Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.
Arazm
A
Farhangfar
The Center of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada.
Rosica
R
Valcheva
Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.
Michael B
MB
Sawyer
The Center of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada.
Levinus
L
Dieleman
University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada ; University of Bonn, Department of Nutritional and Food Sciences, Bonn, Germany.
Andreas
A
Schieber
University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada.
Michael G
MG
Gänzle
Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.
Vickie
V
Baracos
D000818:Animals; D002087:Butyrates / Q000378:metabolism; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000633:toxicity; D002432:Cecum / Q000187:drug effects / Q000201:enzymology; D004043:Dietary Fiber / Q000494:pharmacology*; D005227:Fatty Acids / Q000096:biosynthesis; D005260:Female; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects* / Q000382:microbiology*; D000077146:Irinotecan; D064307:Microbiota / Q000187:drug effects*; D051381:Rats
D002087:Butyrates; D004043:Dietary Fiber; D005227:Fatty Acids; D000077146:Irinotecan; D005966:Glucuronidase; D002166:Camptothecin