Gut microbiota dysbiosis is associated with gastrointestinal mucositis, a common chemotherapy-induced toxicity. Vitamin (Vit)D deficiency correlates with higher cancer incidence and gut inflammation, likely due to VitD’s anti-inflammatory, immune-regulatory, and microbiome-modulatory properties. We aimed to examine how VitD deficiency impacts gut microbiota composition and diversity in mice undergoing chemotherapy treatment.
C57Bl/6 male mice (n=6/group) consumed diet containing 1000 IU/kg or 0 IU/kg of VitD, generating VitD replete or deficient mice, respectively, for five weeks pre-chemotherapy. Five days pre-chemotherapy, mice received daily subcutaneous injections for seven days of 6.25 mg/kg 25-hydroxyvitamin-D (25D), 500ng/kg VD1-6 (catabolism inhibitor), 25D + VD1-6 (VitD treatments) or saline (vehicle control). After five days, mice received 300 mg/kg of 5-fluorouracil (5-FU) or saline, and humanely killed 48 hours later.
Colon contents were aseptically collected, and DNA was extracted. PacBio Long Read Sequencing was conducted (Australian Genomics Research Facility) and analysed using CLC-Genomics Workbench Software (Version 23.0, Qiagen), assessing microbial relative abundance and alpha diversity at the family level.
In vitD deficiency alone the relative abundance of Erysipelotrichacea was higher and the relative abundance of Coprobacteraceae, Muribacteria, Bacteriodaceae and Marinifilaceae was lower compared to VitD-replete mice. After 5-FU administration during VitD deficiency, the relative abundances of Akkermansiaceae, Coprobacteracaea, Muribaculacaea and Bacteroidaceae were higher, and Lachnospiraceae and Eryslpelotrichaceae relative abundance lowered compared with VitD-deficient mice. VitD treatments preserved microbiota composition, the relative abundance of Lachnospiraceae was higher in all VitD treatment groups, and Lactobacillaceae relative abundance was higher within some treatment groups. Alpha diversity significantly decreased with VitD deficiency. VitD treatments did not increase alpha diversity compared with VitD deficiency, despite a trend with VD1-6.
5-FU disrupts gut microbiota composition and diversity, exacerbated by VitD deficiency. VitD treatments (VD1-6, 25D and 25D/VD1-6) can mitigate some microbiota changes caused by 5-FU in VitD-deficient mice.