2 results
Microbiome transfer between IL-1RI-/- and wild-type mice during high or low-fat feeding alters metabolic tissue functionality but not glucose homeostasis.
- Jessica C. Ralston, Kathleen A.J. Mitchelson, Gina M. Lynch, Tam T.T. Tran, Conall R. Strain, Yvonne M. Lenighan, Elaine B. Kennedy, Fiona C. McGillicuddy, Paul W. O'Toole, Helen M. Roche
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E92
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Reduced inflammatory signaling (IL-1RI-/-) alters metabolic responses to dietary challenges (1). Inflammasome deficiency (e.g. IL-18-/-, Asc-/-) can modify gut microbiota concomitant with hepatosteatosis; an effect that was transferable to wild-type (WT) mice by co-housing (2). Taken together, this evidence suggests that links between diet, microbiota and IL-1RI-signaling can influence metabolic health. Our aim was to determine whether IL-1RI-mediated signaling interacted with the gut microbiome to impact metabolic tissue functionality in a diet-specific fashion. Male WT (C57BL/J6) and IL-1RI-/- mice were fed either high-fat diet (HFD; 45% kcal) or low-fat diet (LFD; 10% kcal) for 24 weeks and were housed i) separately by genotype or ii) with genotypes co-housed together (i.e. isolated vs shared microbial environment; n = 8–10 mice per group). Glucose tolerance and insulin secretion response (1.5 g/kg i.p.), gut microbiota composition and caecal short-chain fatty acids (SCFA) were assessed. Liver and adipose tissue were harvested and examined for triacylglycerol (TAG) formation, cholesterol and metabolic markers (Fasn, Cpt1α, Pparg, Scd1, Dgat1/2), using histology, gas-chromatography and RT-PCR, respectively. Statistical analysis included 1-way or 2-way ANOVA, where appropriate, with Bonferroni post-hoc correction. Co-housing significantly affected gut microbiota composition, illustrated by clustering in PCoA (unweighted UniFrac distance) of co-housed mice but not their single-housed counterparts, on both HFD and LFD. The taxa driving these differences were primarily from Lachnospiraceae and Ruminococcaceae families. Single-housed WT had lower hepatic weight, TAG, cholesterol levels and Fasn despite HFD, an effect lost in their co-housed counterparts, who aligned more to IL-1RI-/- hepatic lipid status. Hepatic Cpt1α was lowest in co-housed WT. Adipose from IL-1RI-/- groups on HFD displayed increased adipocyte size and reduced adipocyte number compared to WT groups, but greater lipogenic potential (Pparg, Scd1, Dgat2) alongside a blunted IL-6 response to pro-inflammatory stimuli (~32%, P = 0.025). Whilst caecal SCFA concentrations were not different between groups, single-housed IL-1RI-/- adipocytes showed greatest sensitivity to SCFA-induced lipogenesis. Interestingly, differences in tissue functionality and gut microbiome occurred despite unaltered glucose tolerance; although there was a trend for phenotypic transfer of body weight via co-housing. For all endpoints examined, similar genotype/co-housing effects were observed for both HFD and LFD with the greatest impacts seen in HFD-fed mice. In conclusion, while the gut microbiome may be an important consideration in dietary interventions, these results question the magnitude of its impact in relation to the IL-1RI-dependent immunometabolism-glucose homeostasis axis.
Baker's yeast (1→3)-β-D-glucan Influences Insulin Sensitivity in Mice with Humanized Obese Diabetic Microbiome in High-Fat Diet-Induced Obesity
- Kathleen A. J. Mitchelson, Elena de Marco Castro, Cara M. Hueston, Gina M. Lynch, Elaine A. Keogh, Tam T.T. Tran, Klara Vlckova, Helen M. Roche, Paul W. O'Toole
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E627
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AbstractIntroduction
β-glucans are naturally occurring polysaccharides which have isoform specific immunomodulatory and metabolic properties(1). Certain yeast (1→3)-β-D-glucan isoforms improve cholesterol(2), glucose(3) and lipid homeostasis(4). Feeding (1→3)-β-D-glucan alters the microbiome of high-fat diet (HFD) induced obese (DIO)/type 2 diabetic (T2D) mice(5). Here we investigated the potential impact of baker's yeast (1→3)-β-D-glucan in mice humanized with gut microbiomes from either obese healthy versus obese diabetic subjects on immune-metabolism within the context of high-fat feeding.
MethodsC57Bl/6J male mice received an antibiotic cocktail of Ampicillin, Metronidazole, Vancomycin, Imipenem and Ciprofloxacin HCl in their drinking water for 6 weeks to diminish the endogenous gut microbiota. Mice were inoculated with microbiota samples obtained from obese healthy (OBH) or diabetic (OBD) humans twice daily for 3 days by oral dosing. Mice were fed a low-fat diet (LFD) (10% kcal) for 4 weeks followed by HFD (45% kcal) with/without baker's yeast (1→3)-β-D-glucan (βG), for 9 weeks. Weight, feed intake, glucose tolerance (1.5g/kg), insulin tolerance (0.5U/kg), hepatic and skeletal lipid levels were examined. Tissue specific molecular markers of metabolism and inflammation, and gut microbiome analysis are being determined to compliment the phenotypic data.
ResultsOBH mice were more glucose tolerant and insulin sensitive than OBD mice, despite equal weight gain and adipose tissue mass. Fasting HOMA-IR, attributable to higher insulin concentrations, was higher in OBD compared to OBH mice. βG supplementation reduced HOMA-IR in OBD mice (P < 0.0611). Hepatic triacylglycerol (TAG) and cholesterol levels were also higher in OBD mice, which were prevented by βG supplementation. Hepatic proteomic, caecal microbiomic and metabolomic analysis is on-going in order to ascertain the impact of the OBD versus OBH dysbosis with/without βG supplementation with specific attention on immune-metabolism.