Effects of High-Fructose Corn Syrup on Bone Health and Gastrointestinal Microbiota in Growing Male Mice

Analysis of the causal relationship between gut microbiota and bone remodeling growth factor from the gene association

BACKGROUND

A growing body of evidence indicates a close association between the gut microbiota (GM) and the bone remodeling (BR) process, raising suspicions that the GM may actively participate in BR by modulating the levels of growth factors. However, the precise causal relationship between them remains unclear. Due to many confounding factors, many microorganisms related to BR growth factors have not been identified. We aimed to elucidate the causal relationship between the GM and BR growth factors.

METHODS

We evaluated the genome-wide association study (GWAS) summary statistics for GM and five common growth factors associated with BR: namely, bone morphogenetic proteins (BMP), transforming growth factors(TGF), insulin growth factors (IGFs), epidermal growth factors (EGFs), and fibroblast growth factors (FGF). The causal relationship between the GM and BR growth factors was studied by double-sample Mendelian randomized analysis. We used five Mendelian randomization (MR) methods, including inverse variance-weighted (IVW), MR-Egger, simple mode, weighted median, and weighted model methods.

RESULTS

Through MR analysis, a total of 56 bacterial genera were co-identified as associated with BMP, TGF, IGF, EGF, and FGF. Among them, eight genera were found to have a causal relationship with multiple growth factors: Marvinbryantia was causally associated with BMP-6 (P = 0.018, OR = 1.355) and TGF-β2 (P = 0.002, OR = 1.475); Lachnoclostridium, BMP-7 (P = 0.021, OR = 0.73) and IGF-1 (P = 0.046, OR = 0.804); Terrisporobacter, TGF-β (P = 0.02, OR = 1.726) and FGF-23 levels (P = 0.016, OR = 1.76); Ruminiclostridium5, TGF-β levels (P = 0.024, OR = 0.525) and FGFR-2 (P = 0.003, OR = 0.681); Erysipelatoclostridium, TGF-β2 (P = 0.001, OR = 0.739) and EGF and its receptor (EGFR) (P = 0.012, OR = 0.795); Eubacterium_brachy_group, FGFR-2 (P = 0.045, OR = 1.153) and EGF (P = 0.013, OR = 0.7); Prevotella9 with EGFR (P = 0.022, OR = 0.818) and FGFR-2 (P = 0.011, OR = 1.233) and Faecalibacterium with FGF-23 (P = 0.02, OR = 2.053) and IGF-1 (P = 0.005, OR = 0.843).

CONCLUSION

We confirmed the causal relationship between the GM and growth factors related to BR, which provides a new perspective for the study of BR, through targeted regulation of specific bacteria to prevent and treat diseases and growth factor-mediated BR disorders.

Fructose dose-dependently influences colon barrier function by regulation of some main physical, immune, and biological factors in rats

Little is known about the effects of fructose on colonic function. Here, forty-eight 7-week-old male SD rats were randomly divided into four groups and given 0, 7.5%, 12.75%, and 35% fructose in diet for 8 weeks respectively to investigate the regulatory influence of fructose on colonic barrier function. The exact amount of fructose intake was tracked and recorded. We showed that fructose affects colonic barrier function in a dose-dependent manner. High-fructose at a dose of 1.69±0.23 g/kg/day could damage the physical barrier function of the colon by down-regulating expression of tight junction proteins (ZO-1 and occludin) and mucus layer biomarkers (MUC2 and TFF3). High fructose reduced sIgA and the anti-inflammatory cytokine (IL-10), induced abdominal fat accumulation and pro-inflammatory cytokines (IL-6 and IL-8), leading to colon inflammation and immune barrier dysfunction. In addition, high-fructose altered the biological barrier of the colon by decreasing the abundance of Blautia, Ruminococcus, and Lactobacillius, and increasing the abundance of Allobaculum at the genus level, leading to a reduction in short-chain fatty acids (SCFAs), amino acids, and carbohydrates, etc. Low fructose at a dose of 0.31±0.05 g/kg/day showed no adverse effects on the colonic barrier. The ability of fructose to affect the colonic barrier through physical, immune, and biological pathways provides additional insight into the intestinal disorders caused by high-fructose diets.

The causality between gut microbiota and ankylosing spondylitis: Insights from a bidirectional two-sample Mendelian randomization analysis

BACKGROUND

The association between gut microbiota and ankylosing spondylitis (AS) has been reported in the literature; however, whether the two are correlative is unclear.

METHODS

Single nucleotide polymorphisms associated with the gut microbiome composition and AS (968 AS cases and 336 191 controls) were obtained from published genome-wide association studies in this two-sample Mendelian randomization (MR) study. The causal relationship between gut microbiota and AS was estimated using the inverse-variance weighted method, and the robustness of our findings was confirmed through a comprehensive series of sensitivity analyses.

RESULTS

Anaerotruncus (OR = 0.9984, 95% CI, 0.9968-0.9999, p = .0405) and Ruminococcaceae UCG002 (OR = 0.9989, 95% CI, 0.9979-0.9999, p = .0375) were protective against AS. Defluviitaleaceae (OR = 1.0015, 95% CI, 1.0005-1.0025, p = .0048), Butyricicoccus (OR = 1.0016, 95% CI, 1.0001-1.0032, p = .0429), Coprococcus 3 (OR = 1.0016, 95% CI, 1.0000-1.0032, p = .0463), and Defluviitaleaceae UCG011 (OR = 1.0016, 95% CI, 1.0005-1.0027, p = .0041) exhibited significant positive correlations with heightened susceptibility to AS. Reverse MR revealed that AS does not affect the gut microbial composition.

CONCLUSION

Our study has established a genetically-based causal relationship between gut microbiota and AS. This finding suggests that we may be able to target and regulate specific bacterial groups in the gut to prevent and treat AS.

A High-Fat, High-Cholesterol Diet Promotes Intestinal Inflammation by Exacerbating Gut Microbiome Dysbiosis and Bile Acid Disorders in Cholecystectomy

Patients with post-cholecystectomy (PC) often experience adverse gastrointestinal conditions, such as PC syndrome, colorectal cancer (CRC), and non-alcoholic fatty liver disease (NAFLD), that accumulate over time. An epidemiological survey further revealed that the risk of cholecystectomy is associated with high-fat and high-cholesterol (HFHC) dietary intake. Mounting evidence suggests that cholecystectomy is associated with disrupted gut microbial homeostasis and dysregulated bile acids (BAs) metabolism. However, the effect of an HFHC diet on gastrointestinal complications after cholecystectomy has not been elucidated. Here, we aimed to investigate the effect of an HFHC diet after cholecystectomy on the gut microbiota-BA metabolic axis and elucidate the association between this alteration and the development of intestinal inflammation. In this study, a mice cholecystectomy model was established, and the levels of IL-Iβ, TNF-α, and IL-6 in the colon were increased in mice fed an HFHC diet for 6 weeks. Analysis of fecal BA metabolism showed that an HFHC diet after cholecystectomy altered the rhythm of the BA metabolism by upregulating liver CPY7A1, CYP8B1, and BSEP and ileal ASBT mRNA expression levels, resulting in increased fecal BA levels. In addition, feeding an HFHC diet after cholecystectomy caused a significant dysbiosis of the gut microbiota, which was characterized by the enrichment of the metabolic microbiota involved in BAs; the abundance of pro-inflammatory gut microbiota and related pro-inflammatory metabolite levels was also significantly higher. In contrast, the abundance of major short-chain fatty acid (SCFA)-producing bacteria significantly decreased. Overall, our study suggests that an HFHC diet after cholecystectomy promotes intestinal inflammation by exacerbating the gut microbiome and BA metabolism dysbiosis in cholecystectomy. Our study also provides useful insights into the maintenance of intestinal health after cholecystectomy through dietary or probiotic intervention strategies.

Effect of high-fructose consumption in pregnancy on the bone growth of offspring rats

Growing evidence suggests that bone health is programmed in early life. Maternal diet may influence the skeletal development of offspring. We aimed to determine the possible effects of high-fructose intake during pregnancy on different aspects of long bone morphology in the offspring of rats and to initially explore the possible mechanisms. Pregnant Sprague-Dawley rats were randomly divided into four groups and intragastrically administered the same dose of distilled water (CON, n = 12), 20 g/kg/day glucose (GLU, n = 12), 10 g/kg/day fructose (LFRU, n = 12), or 20 g/kg/day fructose (HFRU, n = 12) for 21 days during gestation. Computed tomography was used to analyze the cortical and cancellous bones of the distal femur of the offspring rats, and circulating bone metabolic biomarkers were measured using enzyme immunoassay. The results showed that high-fructose intake during pregnancy could decrease body weight, impair glucose metabolism, and increase serum leptin and uric acid in offspring. The offspring in the HFRU group had higher levels of the N-terminal propeptide of type I procollagen (PINP) and the C-telopeptide of type I collagen (CTX). The bone mean density (BMD), the total cross-sectional area inside the periosteal envelope (Tt.Ar), cortical bone area (Ct.Ar), medullary (or marrow) area (Ma.Ar), and trabecular mean density of the offspring in the HFRU group were lower than those in the CON group. Tartrate-resistant acid phosphatase (Trap) staining showed that high-fructose intake during pregnancy could increase the number of osteoclasts and increase the absorption area. Our results suggested that excessive fructose intake during pregnancy could inhibit skeletal development in offspring. Thus, attention to fructose intake during pregnancy is important for bone development in offspring.

Causal relationship in gut microbiota and upper urinary urolithiasis using Mendelian randomization

Background

Several reports in recent years have found an association between gut microbiota and upper urinary urolithiasis. However, the causal relationship between them remains to be clarified.

Methods

Genetic variation is used as a tool in Mendelian randomization for inference of whether exposure factors have a causal effect on disease outcomes. We selected summary statistics from a large genome-wide association study of the gut microbiome published by the MiBioGen consortium with a sample size of 18,340 as an exposure factor and upper urinary urolithiasis data from FinnGen GWAS with 4,969 calculi cases and 213,445 controls as a disease outcome. Then, a two-sample Mendelian randomization analysis was performed by applying inverse variance-weighted, MR-Egger, maximum likelihood, and weighted median. In addition, heterogeneity and horizontal pleiotropy were excluded by sensitivity analysis.

Results

IVW results confirmed that class Deltaproteobacteria (OR = 0.814, 95% CI: 0.666-0.995, P = 0.045), order NB1n (OR = 0.833, 95% CI: 0.737-0.940, P = 3.15 × 10^-3), family Clostridiaceae1 (OR = 0.729, 95% CI: 0.581-0.916, P = 6.61 × 10^-3), genus Barnesiella (OR = 0.695, 95% CI: 0.551-0.877, P = 2.20 × 10^-3), genus Clostridium sensu_stricto_1 (OR = 0.777, 95% CI: 0.612-0.986, P = 0.0380), genus Flavonifractor (OR = 0.711, 95% CI: 0.536-0.944, P = 0.0181), genus Hungatella (OR = 0.829, 95% CI: 0.690-0.995, P = 0.0444), and genus Oscillospira (OR = 0.758, 95% CI: 0.577-0.996, P = 0.0464) had a protective effect on upper urinary urolithiasis, while Eubacterium xylanophilum (OR =1.26, 95% CI: 1.010-1.566, P = 0.0423) had the opposite effect. Sensitivity analysis did not find outlier SNPs.

Conclusion

In summary, a causal relationship was found between several genera and upper urinary urolithiasis. However, we still need further randomized controlled trials to validate.

The associations of gut microbiota, endocrine system and bone metabolism

Gut microbiota is of great importance in human health, and its roles in the maintenance of skeletal homeostasis have long been recognized as the "gut-bone axis." Recent evidence has indicated intercorrelations between gut microbiota, endocrine system and bone metabolism. This review article discussed the complex interactions between gut microbiota and bone metabolism-related hormones, including sex steroids, insulin-like growth factors, 5-hydroxytryptamine, parathyroid hormone, glucagon-like peptides, peptide YY, etc. Although the underlying mechanisms still need further investigation, the regulatory effect of gut microbiota on bone health via interplaying with endocrine system may provide a new paradigm for the better management of musculoskeletal disorders.

Associations between Macronutrients Intake and Bone Mineral Density: A Longitudinal Analysis of the Health Workers Cohort Study Participants

OBJECTIVE

This study aimed to evaluate the association between macronutrient intake and bone mineral density (BMD) using non-substitution and substitution statistical approaches.

DESIGN

Longitudinal analysis.

SETTINGS AND PARTICIPANTS

1,317 adults in the Health Worker Cohort Study in Mexico.

MEASUREMENTS

These participants were assessed at baseline (2004-2006) and follow-up (2010-2012). Dietary intakes were assessed using validated food frequency questionnaires. BMD at the different sites was performed by dual-energy X-ray absorptiometry (DXA). Hybrid-mixed effects regression models were performed to evaluate the associations of interest.

RESULTS

Cross-sectional associations were found between fiber intake and higher total hip and femoral neck BMD in women and longitudinal associations with loss of femoral neck BMD in men. An increase in 5% energy intake from carbohydrate was associated with a BMD loss at several site in women and total hip and femoral neck in men. In both sexes, an increase in 5% energy intake of animal protein or fat was associated with a site-specific BMD gain after six years. Substitution analysis showed that the energy intake replacement from fat or carbohydrate by protein had an increase in BMD at different sites in women; while in men, it was only significant when replacing carbohydrate. Substitution of protein or fat by carbohydrates was associated with lower BMD in women, and only protein replacement by carbohydrates in men.

CONCLUSION

Our findings suggest that carbohydrate intake was associated with loss of BMD, while animal protein and fat intake was associated with gain of BMD among the Mexican population. Macronutrient substitutions resulted in significant associations; however, additional studies are needed to confirm these findings.

Liver Transcriptome and Gut Microbiome Analysis Reveals the Effects of High Fructose Corn Syrup in Mice

High fructose corn syrup (HFCS) is a viscous mixture of glucose and fructose that is used primarily as a food additive. This article explored the effect of HFCS on lipid metabolism-expressed genes and the mouse gut microbiome. In total, ten 3-week-old male C57BL/6J mice were randomly divided into two groups, including the control group, given purified water (Group C) and 30% HFCS in water (Group H) for 16 weeks. Liver and colonic content were collected for transcriptome sequencing and 16S rRNA gene sequencing, respectively. HFCS significantly increased body weight, epididymal, perirenal fat weight in mice (p < 0.05), and the proportion of lipid droplets in liver tissue. The expression of the ELOVL fatty acid elongase 3 (Elovl3) gene was reduced, while Stearoyl-Coenzyme A desaturase 1 (Scd1), peroxisome proliferator activated receptor gamma (Pparg), fatty acid desaturase 2 (Fads2), acyl-CoA thioesterase 2 (Acot2), acyl-CoA thioesterase 2 (Acot3), acyl-CoA thioesterase 4 (Acot4), and fatty acid binding protein 2 (Fabp2) was increased in Group H. Compared with Group C, the abundance of Firmicutes was decreased in Group H, while the abundance of Bacteroidetes was increased, and the ratio of Firmicutes/Bacteroidetes was obviously decreased. At the genus level, the relative abundance of Bifidobacterium, Lactobacillus, Faecalibaculum, Erysipelatoclostridium, and Parasutterella was increased in Group H, whereas that of Staphylococcus, Peptococcus, Parabacteroides, Donghicola, and Turicibacter was reduced in Group H. Pparg, Acot2, Acot3, and Scd1 were positively correlated with Erysipelatoclostridium and negatively correlated with Parabacteroides, Staphylococcus, and Turicibacter. Bifidobacterium was negatively correlated with Elovl3. Overall, HFCS affects body lipid metabolism by affecting the expression of lipid metabolism genes in the liver through the gut microbiome.