Gut microbiota diversity is associated with cardiorespiratory fitness in post-primary treatment breast cancer survivors.

NEW FINDINGS: What is the central question of this study? Does the link between cardiorespiratory fitness and gut microbiota diversity persist after adjusting for the potential effects of percentage body fat and activity-related energy expenditure (AEE)? What is the main finding and its importance? This is the first study to examine the link between cardiorespiratory fitness and gut microbiota diversity while accounting for the underlying effects of percentage body fat and free-living AEE. Results from the present work suggest that cardiorespiratory fitness, not physical activity, is a superior correlate of gut microbiota diversity among post-primary treatment, non-metastatic breast cancer survivors. ABSTRACT: Cancer treatment uniquely triggers multiple physiological shifts detrimental to overall health. Although previous research indicates a link between the gut microbiota and cardiorespiratory fitness, it is unclear whether these findings are attributable to potential underlying effects of percentage body fat or free-living activity energy expenditure (AEE). The microbe composition of faecal specimens from 37 breast cancer survivors was determined using 16S microbiome analyses. Individual-sample microbiota diversity (α-diversity) and between-sample community differences (ß-diversity) were examined. Peak oxygen uptake ( V̇O2peak ) was estimated from a graded exercise test consistent with the modified Naughton protocol, in which exercise terminates at 85% of age-predicted maximal heart rate. The AEE was measured over 10 days using doubly labelled water, wherein the percentage body fat was calculated from total body water. Pearson correlations revealed α-diversity indices (Chao1, observed species, PD whole tree and Shannon) to be positively associated with V̇O2peak (r = 0.34-0.51; P < 0.05), whereas the percentage of maximal heart rate during stages 1-4 of the graded exercise test (r = -0.34 to -0.50; P < 0.05) and percentage body fat (r = -0.32 to -0.41; P < 0.05) were negatively associated with the same α-diversity indices. Multiple linear regression models showed that V̇O2peak accounted for 22 and 26% of the variance in taxonomic richness (observed species) and phylogenic diversity after adjustment for percentage body fat and menopausal status. Unweighted UniFrac (ß-diversity) was significant for several outcomes involving cardiorespiratory fitness, and significant taxa comparisons were found. Associations between gut microbiota and free-living AEE were not found. Results from the present work suggest that cardiorespiratory fitness, not physical activity, is a superior correlate of gut microbiota diversity.

Gut microbiota composition associated with alterations in cardiorespiratory fitness and psychosocial outcomes among breast cancer survivors.

PURPOSE: In this proof-of-concept pilot study, our purpose was to determine correlations between gut microbiota composition and alterations in cardiorespiratory fitness and psychosocial outcomes among post-primary treatment breast cancer survivors (BCS). METHODS: Composition of the gut microbiota in BCS (n = 12) was assessed at baseline (M0) and at the end of 3 months (M3) using Illumina MiSeq DNA Sequencing of the 16S rRNA gene. Gut microbiota composition was analyzed using the QIIME bioinformatics software and represented through diversity metrics and taxa analyses. Cardiorespiratory fitness, fatigue, anxiety, depression, and sleep dysfunction were assessed at M0 and M3 via the submaximal treadmill test, Fatigue Symptom Inventory, Hospital Anxiety and Depression Scale, and Pittsburgh Sleep Quality Index, respectively. RESULTS: Increased fatigue interference in BCS was associated with increased mean within-sample Shannon diversity (organism richness and evenness) (p = 0.009). Weighted UniFrac analysis (shifts in taxa relative abundance) revealed significant differences in between-sample (beta) diversity for changes in fatigue interference (p = 0.01) and anxiety (p = 0.022), with a trend observed for fatigue intensity and sleep dysfunction (p < 0.1). Unweighted UniFrac analysis (shifts in taxa types) found significant beta diversity differences for cardiorespiratory fitness (p = 0.026). Prior to false discovery correction (FDR), changes in fitness, fatigue, anxiety, and sleep dysfunction were associated with the frequency of certain gut bacteria genera (e.g., Faecalibacterium, Prevotella, Bacteroides) (p < 0.05). CONCLUSIONS: Correlations may exist between alterations in gut microbiota composition and longitudinal changes in cardiorespiratory fitness, fatigue, and anxiety in BCS. Further research examining the role of the microbiota-gut-brain axis in exercise-induced effects on psychosocial outcomes in BCS is warranted.