A metagenome-wide association study of gut microbiome and visceral fat accumulation

Integrative metagenomic analysis reveals distinct gut microbial signatures related to obesity

Obesity is a metabolic disorder closely associated with profound alterations in gut microbial composition. However, the dynamics of species composition and functional changes in the gut microbiome in obesity remain to be comprehensively investigated. In this study, we conducted a meta-analysis of metagenomic sequencing data from both obese and non-obese individuals across multiple cohorts, totaling 1351 fecal metagenomes. Our results demonstrate a significant decrease in both the richness and diversity of the gut bacteriome and virome in obese patients. We identified 38 bacterial species including Eubacterium sp. CAG:274, Ruminococcus gnavus, Eubacterium eligens and Akkermansia muciniphila, and 1 archaeal species, Methanobrevibacter smithii, that were significantly altered in obesity. Additionally, we observed altered abundance of five viral families: Mesyanzhinovviridae, Chaseviridae, Salasmaviridae, Drexlerviridae, and Casjensviridae. Functional analysis of the gut microbiome indicated distinct signatures associated to obesity and identified Ruminococcus gnavus as the primary driver for function enrichment in obesity, and Methanobrevibacter smithii, Akkermansia muciniphila, Ruminococcus bicirculans, and Eubacterium siraeum as functional drivers in the healthy control group. Additionally, our results suggest that antibiotic resistance genes and bacterial virulence factors may influence the development of obesity. Finally, we demonstrated that gut vOTUs achieved a diagnostic accuracy with an optimal area under the curve of 0.766 for distinguishing obesity from healthy controls. Our findings offer comprehensive and generalizable insights into the gut bacteriome and virome features associated with obesity, with the potential to guide the development of microbiome-based diagnostics.

Construction and Identification of a Breast Bioreactor for Human-Derived Hypoglycemic Protein Amylin

The mammary gland of mammals can generate numerous bioactive proteins. To express the human amylin protein in the mammary glands of domestic animals, we engineered a transgenic mammary gland bioreactor. For this study, we produced transgenic mice through prokaryotic microinjection. RT-PCR, qPCR, and Western blotting confirmed the presence of transgenes in the mice. The ELISA assay indicated an amylin yield of approximately 1.44 μg/mL in the mice milk. Further research revealed that consuming milk containing amylin resulted in a slight, but insignificant enhancement in food consumption, blood sugar equilibrium, and glucose tolerance. The influence of amylin-fortified milk on the abundance of fecal strains in mice was examined, and a significant difference in the quantity of strains needed for fatty acid synthesis and metabolism was discovered. The amylin protein gathered from humans is safe to consume, as no harmful effects were detected in the mice. Our study examined the production of human amylin using a new safety strategy that could potentially alleviate diabetic symptoms in the future through oral administration of milk containing amylin.

Microbiome and metabolome dysbiosis analysis in impaired glucose tolerance for the prediction of progression to diabetes mellitus

Gut microbiota and circulating metabolite dysbiosis predate important pathological changes in glucose metabolic disorders; however, comprehensive studies on impaired glucose tolerance (IGT), a diabetes mellitus (DM) precursor, are lacking. Here, we perform metagenomic sequencing and metabolomics on 47 pairs of individuals with IGT and newly diagnosed DM and 46 controls with normal glucose tolerance (NGT); patients with IGT are followed up after 4 years for progression to DM. Analysis of baseline data reveals significant differences in gut microbiota and serum metabolites among the IGT, DM, and NGT groups. In addition, 13 types of gut microbiota and 17 types of circulating metabolites showed significant differences at baseline before IGT progressed to DM, including higher levels of Eggerthella unclassified, Coprobacillus unclassified, Clostridium ramosum, L-valine, L-norleucine, and L-isoleucine, and lower levels of Eubacterium eligens, Bacteroides faecis, Lachnospiraceae bacterium 3_1_46FAA, Alistipes senegalensis, Megaspaera elsdenii, Clostridium perfringens, α-linolenic acid, 10E,12Z-octadecadienoic acid, and dodecanoic acid. A random forest model based on differential intestinal microbiota and circulating metabolites can predict the progression from IGT to DM (AUC = 0.87). These results suggest that microbiome and metabolome dysbiosis occur in individuals with IGT and have important predictive values and potential for intervention in preventing IGT from progressing to DM.

Interactome Analysis of Visceral Adipose Tissue Elucidates Gene Regulatory Networks and Novel Gene Candidates in Obesity

Objective

Visceral adiposity is associated with increased proinflammatory activity, insulin resistance, diabetes risk and mortality rate. Numerous individual genes have been associated with obesity, but studies investigating gene-regulatory networks in human visceral obesity are lacking.

Methods

We analyzed gene-regulatory networks in human visceral adipose tissue (VAT) from 48 obese and 11 non-obese Chinese subjects using gene co-expression and network construction with RNA-sequencing data. We also conducted RNA interference-based tests on selected genes for adipocyte differentiation effects.

Results

A scale-free gene co-expression network was constructed from 360 differentially expressed genes between obese and non-obese VAT (absolute log fold-change >1, FDR<0.05) with edge probability >0.8. Gene regulatory network analysis identified candidate transcription factors associated with differentially expressed genes. Fifteen subnetworks (communities) displayed altered connectivity patterns between obese and non-obese networks. Genes in pro-inflammatory pathways showed increased network connectivities in obese VAT whereas the oxidative phosphorylation pathway displayed reduced connections (enrichment FDR<0.05). Functional screening via RNA interference identified SOX30 and OSBPL3 as potential network-derived gene candidates influencing adipocyte differentiation.

Conclusions

This interactome-based approach highlights the network architecture, identifies novel candidate genes, and leads to new hypotheses regarding network-assisted gene regulation in obese vs. non-obese VAT.What is already known about this subject?: Visceral adipose tissue (VAT) is associated with increased levels of proinflammatory activity, insulin resistance, diabetes risk and mortality rate.Gene expression studies have identified candidate genes associated with proinflammatory function in VAT.What are the new findings in your manuscript?: Using integrative network-science, we identified co-expression and gene regulatory networks that are differentially regulated in VAT samples from subjects with and without obesityWe used functional testing (adipocyte differentiation) to validate a subset of novel candidate genes with minimal prior reported associations to obesityHow might your results change the direction of research or the focus of clinical practice: Network biology-based investigation provides a new avenue to our understanding of gene function in visceral adiposityFunctional validation screen allows for the identification of novel gene candidates that may be targeted for the treatment of adipose tissue dysfunction in obesity.

Causal relationship between gut microbiota with subcutaneous and visceral adipose tissue: a bidirectional two-sample Mendelian Randomization study

Background

Numerous studies have revealed associations between gut microbiota and adipose tissue. However, the specific functional bacterial taxa and their causal relationships with adipose tissue production in different regions of the body remain unclear.

Methods

We conducted a bidirectional two-sample Mendelian Randomization (MR) study using aggregated data from genome-wide association studies (GWAS) for gut microbiota and adipose tissue. We employed methods such as inverse variance weighted (IVW), MR Egger, weighted median, simple mode, and weighted mode to assess the causal relationships between gut microbiota and subcutaneous adipose tissue (SAT) as well as visceral adipose tissue (VAT). Cochran's Q test, MR-Egger regression intercept analysis, and MR-PRESSO were used to test for heterogeneity, pleiotropy, and outliers of the instrumental variables, respectively. Reverse MR was employed to evaluate the reverse causal relationships between SAT, VAT, and gut microbiota with significant associations.

Results

IVW results demonstrated that Betaproteobacteria were protective factors for SAT production (OR = 0.88, 95% CI: 0.80-0.96, p = 0.005) and VAT production (OR = 0.91, 95% CI: 0.83-0.99, p = 0.030). Various bacterial taxa including Ruminococcaceae UCG002 (OR = 0.94, 95% CI: 0.89-0.99, p = 0.017), Methanobacteria class (OR = 0.96, 95% CI: 0.92-1.00, p = 0.029), and Burkholderiales (OR = 0.90, 95% CI: 0.83-0.98, p = 0.012) were associated only with decreased SAT production. Rikenellaceae RC9 gut group (OR = 1.05, 95% CI: 1.02-1.10, p = 0.005), Eubacterium hallii group (OR = 1.08, 95% CI: 1.01-1.15, p = 0.028), Peptococcaceae (OR = 1.08, 95% CI: 1.01-1.17, p = 0.034), and Peptococcus (OR = 1.05, 95% CI: 1.00-1.10, p = 0.047) were risk factors for SAT production. Meanwhile, Eubacterium fissicatena group (OR = 0.95, 95% CI: 0.91-0.99, p = 0.019), Turicibacter (OR = 0.93, 95% CI: 0.88-0.99, p = 0.022), and Defluviitaleaceae UCG011 (OR = 0.94, 95% CI: 0.89-0.99, p = 0.024) were protective factors for VAT production. Furthermore, Bacteroidetes (OR = 1.09, 95% CI: 1.01-1.17, p = 0.018), Eubacterium eligens group (OR = 1.09, 95% CI: 1.01-1.19, p = 0.037), Alloprevotella (OR = 1.05, 95% CI: 1.00-1.10, p = 0.038), and Phascolarctobacterium (OR = 1.07, 95% CI: 1.00-1.15, p = 0.042) were associated with VAT accumulation. Additionally, reverse MR revealed significant associations between SAT, VAT, and Rikenellaceae RC9 gut group (IVW: OR = 1.57, 95% CI: 1.18-2.09, p = 0.002) as well as Betaproteobacteria (IVW: OR = 1.14, 95% CI: 1.01-1.29, p = 0.029), both acting as risk factors. Sensitivity analyzes during bidirectional MR did not identify heterogeneity or pleiotropy.

Conclusion

This study unveils complex causal relationships between gut microbiota and SAT/VAT, providing novel insights into the diagnostic and therapeutic potential of gut microbiota in obesity and related metabolic disorders.

Social and psychological adversity are associated with distinct mother and infant gut microbiome variations

Health disparities are driven by underlying social disadvantage and psychosocial stressors. However, how social disadvantage and psychosocial stressors lead to adverse health outcomes is unclear, particularly when exposure begins prenatally. Variations in the gut microbiome and circulating proinflammatory cytokines offer potential mechanistic pathways. Here, we interrogate the gut microbiome of mother-child dyads to compare high-versus-low prenatal social disadvantage, psychosocial stressors and maternal circulating cytokine cohorts (prospective case-control study design using gut microbiomes from 121 dyads profiled with 16 S rRNA sequencing and 89 dyads with shotgun metagenomic sequencing). Gut microbiome characteristics significantly predictive of social disadvantage and psychosocial stressors in the mothers and children indicate that different discriminatory taxa and related pathways are involved, including many species of Bifidobacterium and related pathways across several comparisons. The lowest inter-individual gut microbiome similarity was observed among high-social disadvantage/high-psychosocial stressors mothers, suggesting distinct environmental exposures driving a diverging gut microbiome assembly compared to low-social disadvantage/low-psychosocial stressors controls (P = 3.5 × 10-5 for social disadvantage, P = 2.7 × 10-15 for psychosocial stressors). Children's gut metagenome profiles at 4 months also significantly predicted high/low maternal prenatal IL-6 (P = 0.029), with many bacterial species overlapping those identified by social disadvantage and psychosocial stressors. These differences, based on maternal social and psychological status during a critical developmental window early in life, offer potentially modifiable targets to mitigate health inequities.

Impact of dietary interventions on pre-diabetic oral and gut microbiome, metabolites and cytokines

Diabetes and associated comorbidities are a global health threat on the rise. We conducted a six-month dietary intervention in pre-diabetic individuals (NCT03222791), to mitigate the hyperglycemia and enhance metabolic health. The current work explores early diabetes markers in the 200 individuals who completed the trial. We find 166 of 2,803 measured features, including oral and gut microbial species and pathways, serum metabolites and cytokines, show significant change in response to a personalized postprandial glucose-targeting diet or the standard of care Mediterranean diet. These changes include established markers of hyperglycemia as well as novel features that can now be investigated as potential therapeutic targets. Our results indicate the microbiome mediates the effect of diet on glycemic, metabolic and immune measurements, with gut microbiome compositional change explaining 12.25% of serum metabolites variance. Although the gut microbiome displays greater compositional changes compared to the oral microbiome, the oral microbiome demonstrates more changes at the genetic level, with trends dependent on environmental richness and species prevalence in the population. In conclusion, our study shows dietary interventions can affect the microbiome, cardiometabolic profile and immune response of the host, and that these factors are well associated with each other, and can be harnessed for new therapeutic modalities.

Sodium butyrate promotes gastrointestinal development of preweaning bull calves via inhibiting inflammation, balancing nutrient metabolism, and optimizing microbial community functions

Butyrate promotes the growth and gastrointestinal development of calves. But, the mechanisms behind its effects on signaling pathways of the gastrointestinal tract and rumen microbiome is unclear. This study aimed to reveal transcriptomic pathways of gastrointestinal epithelium and microbial community in response to butyrate supplementation in calves fed a high fiber starter. Fourteen Holstein bull calves (39.9 ± 3.7 kg, 14 d of age) were assigned to 2 groups (sodium butyrate group, SB; control group, Ctrl). The SB group received 0.5% SB supplementation. At d 51, the calves were slaughtered to obtain samples for analysis of the transcriptome of the rumen and jejunum epithelium as well as ruminal microbial metagenome. Sodium butyrate supplementation resulted in a higher performance in average daily gain and development of jejunum and rumen papillae. In both the rumen and jejunum epithelium, SB down-regulated pathways related to inflammation including NF-κB (PPKCB, CXCL8, CXCL12), interleukin-17 (IL17A, IL17B, MMP9), and chemokine (CXCL12, CCL4, CCL8) and up-regulated immune pathways including the intestinal immune network for immunoglobulin A (IgA) production (CD28). Meanwhile, in the jejunum epithelium, SB regulated pathways related to nutritional metabolism including nitrogen metabolism (CA1, CA2, CA3), synthesis and degradation of ketone bodies (HMGCS2, BDH1, LOC100295719), fat digestion and absorption (PLA2G2F, APOA1, APOA4), and the PPAR signaling pathway (FABP4, FABP6, CYP4A11). The metagenome showed that SB greatly increased the relative abundance of Bacillus subtilis and Eubacterium limosum, activated ruminal microbial carbohydrate metabolism pathways and increased the abundance of carbohydrate hydrolysis enzymes. In conclusion, butyrate exhibited promoting effects on growth and gastrointestinal development by inhibiting inflammation, enhancing immunity and energy harvesting, and activating microbial carbohydrate metabolism. These findings provide new insights into the potential mechanisms behind the beneficial effects of butyrate in calf nutrition.

The gut microbiome and regional fat distribution: Findings from the Baltimore Longitudinal Study of Aging

OBJECTIVE

The aim of this study was to examine associations of gut microbiome diversity and composition with directly measured regional fat distribution, including central fat, in a large community-based cohort.

METHODS

A cross-sectional investigation was conducted in the Baltimore Longitudinal Study of Aging (N = 815, 55.2% female, 65.9% White). The fecal microbiome was assessed using whole-genome shotgun metagenomic sequencing, and trunk and leg fat was measured using dual x-ray absorptiometry. Multivariable-adjusted associations of regional fat measures, BMI, or waist circumference with microbiome alpha diversity metrics, microbiome beta diversity metrics, and species differential abundance (verified using two compositional statistical approaches) were examined.

RESULTS

Trunk fat, leg fat, BMI, and waist circumference all significantly explained similar amounts of variance in microbiome structure. Differential abundance testing identified 11 bacterial species significantly associated with at least one measure of body composition or anthropometry. Ruminococcus gnavus was strongly and consistently associated with trunk fat mass, which is congruent with prior literature.

CONCLUSIONS

Microbiome diversity and composition, in particular higher abundance of Ruminococcus gnavus, were associated with greater trunk fat, in addition to other measures of obesity. Longitudinal studies are needed to replicate these findings, and if replicated, randomized trials are needed to determine whether interventions targeting microbiome features such as abundance of Ruminococcus gnavus can lead to reductions in trunk fat and its metabolic sequelae.

Visceral adipose tissue-directed human kallistatin gene therapy improves adipose tissue remodeling and metabolic health in obese mice

OBJECTIVE

Adipose tissue remodeling is a dynamic process that is pathologically expedited in the obese state and is closely related to obesity-associated disease progression. This study aimed to explore the effects of human kallistatin (HKS) on adipose tissue remodeling and obesity-related metabolic disorders in mice fed with a high-fat diet (HFD).

METHODS

Adenovirus-mediated HKS cDNA (Ad.HKS) and a blank adenovirus (Ad.Null) were constructed and injected into the epididymal white adipose tissue (eWAT) of 8-weeks-old male C57B/L mice. The mice were fed normal or HFD for 28 days. The body weight and circulating lipids levels were assessed. Intraperitoneal glucose tolerance test (IGTT) and insulin tolerance test (ITT) were also performed. Oil-red O staining was used to assess the extent of lipid deposition in the liver. Immunohistochemistry and HE staining were used to measure HKS expression, adipose tissue morphology, and macrophage infiltration. Western blot and qRT-PCR were used to evaluate the expression of adipose function-related factors.

RESULTS

At the end of the experiment, the expression of HKS in the serum and eWAT of the Ad.HKS group was higher than in the Ad.Null group. Furthermore, Ad.HKS mice had lower body weight and decreased serum and liver lipid levels after four weeks of HFD feeding. IGTT and ITT showed that HKS treatment maintained balanced glucose homeostasis. Additionally, inguinal white adipose tissue (iWAT) and eWAT in Ad.HKS mice had a higher number of smaller-size adipocytes and had less macrophage infiltration than Ad.Null group. HKS significantly increased the mRNA levels of adiponectin, vaspin, and eNOS. In contrast, HKS decreased RBP4 and TNFα levels in the adipose tissues. Western blot results showed that local injection of HKS significantly upregulated the protein expressions of SIRT1, p-AMPK, IRS1, p-AKT, and GLUT4 in eWAT.

CONCLUSIONS

HKS injection in eWAT improves HFD-induced adipose tissue remodeling and function, thus significantly improving weight gain and dysregulation of glucose and lipid homeostasis in mice.

Bifidobacterium lactis IDCC 4301 Exerts Anti-Obesity Effects in High-Fat Diet-Fed Mice Model by Regulating Lipid Metabolism

SCOPE

Chronic hypernutrition promotes lipid accumulation in the body and excessive lipid accumulation leads to obesity. An increase in the number and size of adipocytes, a characteristic of obesity is closely associated with adipose dysfunction. Recent in vitro and in vivo studies have shown that probiotics may prevent this dysfunction by regulating lipid metabolism. However, the mechanisms of action of probiotics in obesity are not fully understood and their usage for treating obesity remains limited.

METHODS AND RESULTS

Bifidobacterium lactis IDCC 4301 is selected for its anti-obesity potential after evaluating inhibitory activity of pancreatic lipase and cholesterol reducing activity. Next, this study investigates the roles of B. lactis IDCC 4301 on lipid metabolism in 3T3-L1 preadipocytes and high-fat diet (HFD)-fed mice. B. lactis IDCC 4301 inhibits cell differentiation and lipid accumulation by suppressing the expression of adipogenic enzymes in 3T3-L1 cells. Moreover, the administration of B. lactis IDCC 4301 decreases body and adipose tissue weight, improves serum lipid levels, and downregulates adipogenic mRNA expression in HFD-fed mice. Additionally, metabolomic analysis suggests that 2-ketobutyrate should be a possible target compound against obesity.

CONCLUSIONS

B. lactis IDCC 4301 may be used as an alternative treatment for obesity.

Application of High-Throughput Sequencing (HTS) to Enhance the Well-Being of an Endangered Species (Malayan Tapir): Characterization of Gut Microbiome Using MG-RAST

The Tapirus indicus, also known as Malayan tapir, has been listed as a rapidly declining animal species in the past decades, along with being declared and categorized as an endangered species by the International Union for Conservation of Nature (IUCN) 2016. This tapir species is geographically distributed across several countries in Southeast Asia such as Peninsular Malaysia, Indonesia (Sumatra), South Thailand, and Myanmar. Amongst these countries, the Peninsula Malaysia forest is recorded to contain the highest number of Malayan tapir population. Unfortunately, in the past decades, the population of Malayan tapirs has declined swiftly due to serious deforestation, habitat fragmentation, and heavy vehicle accidents during road crossings at forest routes. Concerned by this predicament, the Department of Wildlife and National Parks (DWNP) Peninsular Malaysia collaborated with a few local universities to conduct various studies aimed at increasing the population number of tapirs in Malaysia. Several studies were conducted with the aim of enhancing the well-being of tapirs in captivity. Veterinarians face problems when it comes to selecting healthy and suitable tapirs for breeding programs at conservation centers. Conventional molecular methods using high-throughput sequencing provides a solution in determining the health condition of Malayan tapirs using the Next-Generation Sequencing (NGS) technology. Unaware by most, gut microbiome plays an important role in determining the health condition of an organism by various aspects: (1) digestion control; (2) benefiting the immune system; and (3) playing a role as a "second brain." Commensal gut bacterial communities (microbiomes) are predicted to influence organism health and disease. Imbalance of unhealthy and healthy microbes in the gut may contribute to weight gain, high blood sugar, high cholesterol, and other disorders. In infancy, neonatal gut microbiomes are colonized with maternal and environmental flora, and mature toward a stable composition in two to three years. Interactions between the microorganism communities and the host allow for the establishment of microbiological roles. Identifying the core microbiome(s) are essential in the prediction of diseases and changes in environmental behavior of microorganisms. The dataset of 16S rRNA amplicon sequencing of Malayan tapir was deposited in the MG-RAST portal. Parameters such as quality control, taxonomic prediction (unknown and predicted), diversity (rarefaction), and diversity (alpha) were analyzed using sequencing approaches (Amplicon sequencing). Comparisons of parameters, according to the type of sequencing, showed significant differences, except for the prediction variable. In the Amplicon sequencing datasets, the parameters Rarefaction and Unknown had the highest correlation, while Alpha and Predicted had the lowest. Firmicutes, Bacteroidetes, Proteobacteria, Bacilli, and Bacteroidia were the most representative genera in Malayan tapir amplicon sequences, which indicated that most of the tapirs were healthy. However, continuous assessment to maintain the well-being of tapir for long term is still required. This chapter focuses on the introduction of 16S rRNA amplicon metagenomics in analyzing Malayan tapir gut microbiome dataset.

Precision Nutrition: Recent Advances in Obesity

"Precision nutrition" is an emerging area of nutrition research that focuses on understanding metabolic variability within and between individuals and helps develop customized dietary plans and interventions to maintain optimal individual health. It encompasses nutritional genomic (gene-nutrient interactions), epigenetic, microbiome, and environmental factors. Obesity is a complex disease that is affected by genetic and environmental factors and thus a relevant target of precision nutrition-based approaches. Recent studies have shown significant associations between obesity phenotypes (body weight, body mass index, waist circumference, and central and regional adiposity) and genetic variants, epigenetic factors (DNA methylation and noncoding RNA), microbial species, and environment (sociodemographics and physical activity). Additionally, studies have also shown that the interactions between genetic variants, microbial metabolites, and epigenetic factors affect energy balance and adiposity. These include variants in FTO, MC4R, PPAR, APOA, and FADS genes, DNA methylation in CpG island regions, and specific miRNAs and microbial species such as Firmicutes, Bacteriodes, Clostridiales, etc. Similarly, studies have shown that microbial metabolites, folate, B-vitamins, and short-chain fatty acids interact with miRNAs to influence obesity phenotypes. With the advent of next-generation sequencing and analytical approaches, the advances in precision nutrition have the potential to lead to new paradigms, which can further lead to interventions or customized treatments specific to individuals or susceptible groups of individuals. This review highlights the recent advances in precision nutrition as applied to obesity and projects the importance of precision nutrition in obesity and weight management.

Machine learning framework for gut microbiome biomarkers discovery and modulation analysis in large-scale obese population

BACKGROUND

The gut microbiome has proven to be an important factor affecting obesity; however, it remains a challenge to identify consistent biomarkers across geographic locations and perform precisely targeted modulation for obese individuals.

RESULTS

This study proposed a systematic machine learning framework and applied it to 870 human stool metagenomes across five countries to obtain comprehensive regional shared biomarkers and conduct a personalized modulation analysis. In our pipeline, a heterogeneous ensemble feature selection diagram is first developed to determine an optimal subset of biomarkers through the aggregation of multiple techniques. Subsequently, a deep reinforcement learning method was established to alter the targeted composition to the desired healthy target. In this manner, we can realize personalized modulation by counterfactual inference. Consequently, a total of 42 species were identified as regional shared biomarkers, and they showed good performance in distinguishing obese people from the healthy group (area under curve (AUC) =0.85) when demonstrated on validation datasets. In addition, by pooling all counterfactual explanations, we found that Akkermansia muciniphila, Faecalibacterium prausnitzii, Prevotella copri, Bacteroides dorei, Bacteroides eggerthii, Alistipes finegoldii, Alistipes shahii, Eubacterium sp. _CAG_180, and Roseburia hominis may be potential broad-spectrum targets with consistent modulation in the multi-regional obese population.

CONCLUSIONS

This article shows that based on our proposed machine-learning framework, we can obtain more comprehensive and accurate biomarkers and provide modulation analysis for the obese population. Moreover, our machine-learning framework will also be very useful for other researchers to further obtain biomarkers and perform counterfactual modulation analysis in different diseases.

Increased abundance of Ruminococcus gnavus in gut microbiota is associated with moyamoya disease and non-moyamoya intracranial large artery disease

Moyamoya disease (MMD) is a rare cerebrovascular disease endemic in East Asia. The p.R4810K mutation in RNF213 gene confers a risk of MMD, but other factors remain largely unknown. We tested the association of gut microbiota with MMD. Fecal samples were collected from 27 patients with MMD, 7 patients with non-moyamoya intracranial large artery disease (ICAD) and 15 control individuals with other disorders, and 16S rRNA were sequenced. Although there was no difference in alpha diversity or beta diversity between patients with MMD and controls, the cladogram showed Streptococcaceae was enriched in patient samples. The relative abundance analysis demonstrated that 23 species were differentially abundant between patients with MMD and controls. Among them, increased abundance of Ruminococcus gnavus > 0.003 and decreased abundance of Roseburia inulinivorans < 0.002 were associated with higher risks of MMD (odds ratio 9.6, P = 0.0024; odds ratio 11.1, P = 0.0051). Also, Ruminococcus gnavus was more abundant and Roseburia inulinivorans was less abundant in patients with ICAD than controls (P = 0.046, P = 0.012). The relative abundance of Ruminococcus gnavus or Roseburia inulinivorans was not different between the p.R4810K mutant and wildtype. Our data demonstrated that gut microbiota was associated with both MMD and ICAD.

Association between gut microbiota and preeclampsia-eclampsia: a two-sample Mendelian randomization study

BACKGROUND

Several recent observational studies have reported that gut microbiota composition is associated with preeclampsia. However, the causal effect of gut microbiota on preeclampsia-eclampsia is unknown.

METHODS

A two-sample Mendelian randomization study was performed using the summary statistics of gut microbiota from the largest available genome-wide association study meta-analysis (n=13,266) conducted by the MiBioGen consortium. The summary statistics of preeclampsia-eclampsia were obtained from the FinnGen consortium R7 release data (5731 cases and 160,670 controls). Inverse variance weighted, maximum likelihood, MR-Egger, weighted median, weighted model, MR-PRESSO, and cML-MA were used to examine the causal association between gut microbiota and preeclampsia-eclampsia. Reverse Mendelian randomization analysis was performed on the bacteria that were found to be causally associated with preeclampsia-eclampsia in forward Mendelian randomization analysis. Cochran's Q statistics were used to quantify the heterogeneity of instrumental variables.

RESULTS

Inverse variance weighted estimates suggested that Bifidobacterium had a protective effect on preeclampsia-eclampsia (odds ratio = 0.76, 95% confidence interval: 0.64-0.89, P = 8.03 × 10^-4). In addition, Collinsella (odds ratio = 0.77, 95% confidence interval: 0.60-0.98, P = 0.03), Enterorhabdus (odds ratio = 0.76, 95% confidence interval: 0.62-0.93, P = 8.76 × 10^-3), Eubacterium (ventriosum group) (odds ratio = 0.76, 95% confidence interval: 0.63-0.91, P = 2.43 × 10^-3), Lachnospiraceae (NK4A136 group) (odds ratio = 0.77, 95% confidence interval: 0.65-0.92, P = 3.77 × 10^-3), and Tyzzerella 3 (odds ratio = 0.85, 95% confidence interval: 0.74-0.97, P = 0.01) presented a suggestive association with preeclampsia-eclampsia. According to the results of reverse MR analysis, no significant causal effect of preeclampsia-eclampsia was found on gut microbiota. No significant heterogeneity of instrumental variables or horizontal pleiotropy was found.

CONCLUSIONS

This two-sample Mendelian randomization study found that Bifidobacterium was causally associated with preeclampsia-eclampsia. Further randomized controlled trials are needed to clarify the protective effect of probiotics on preeclampsia-eclampsia and their specific protective mechanisms.

The Association between Gut Microbiome and Pregnancy-Induced Hypertension: A Nested Case–Control Study

(1) Background: Pregnancy-induced hypertension (PIH) is associated with obvious microbiota dysbiosis in the third trimester of pregnancy. However, the mechanisms behind these changes remain unknown. Therefore, this study aimed to explore the relationship between the gut microbiome in early pregnancy and PIH occurrence. (2) Methods: A nested case–control study design was used based on the follow-up cohort. Thirty-five PIH patients and thirty-five matched healthy pregnant women were selected as controls. The gut microbiome profiles were assessed in the first trimester using metagenomic sequencing. (3) Results: Diversity analyses showed that microbiota diversity was altered in early pregnancy. At the species level, eight bacterial species were enriched in healthy controls: Alistipes putredinis, Bacteroides vulgatus, Ruminococcus torques, Oscillibacter unclassified, Akkermansia muciniphila, Clostridium citroniae, Parasutterella excrementihominis and Burkholderiales bacterium_1_1_47. Conversely, Eubacterium rectale, and Ruminococcus bromii were enriched in PIH patients. The results of functional analysis showed that the changes in these different microorganisms may affect the blood pressure of pregnant women by affecting the metabolism of vitamin K₂, sphingolipid, lipid acid and glycine. (4) Conclusion: Microbiota dysbiosis in PIH patients begins in the first trimester of pregnancy, and this may be associated with the occurrence of PIH. Bacterial pathway analyses suggest that the gut microbiome might lead to the development of PIH through the alterations of function modules.

Association of Gut Microbiota with Atherogenic Dyslipidemia, and Its Impact on Serum Lipid Levels after Bariatric Surgery

Gut microbiota has been suggested to modulate circulating lipids. However, the relationship between the gut microbiota and atherogenic dyslipidemia (AD), defined as the presence of both low HDL-C and hypertriglyceridemia, is not fully understood. Moreover, because obesity is among the main causes of secondary AD, it is important to analyze the effect of gut microbiota composition on lipid profiles after a weight loss intervention. We compared the microbial diversity and taxonomic composition in patients with AD (n = 41) and controls (n = 38) and sought correlations of genera abundance with serum lipid levels in 20 patients after weight loss induced by Roux-en-Y gastric bypass (RYGB) surgery. Gut microbiota composition was profiled using next-generation sequencing of 16S rRNA. Gut microbiota diversity was significantly lower in atherogenic dyslipidemia. Moreover, relative abundance of two genera with LDA score >3.5 (Megasphaera and LPS-producing Escherichia-Shigella), was significantly higher in AD subjects, while the abundance of four short chain fatty acids (SCFA) producing-genera (Christensenellaceae R-7, Ruminococcaceae UCG-014; Akkermansia and [Eubacterium] eligens group) was significantly higher in controls. Notably, [Eubacterium] eligens group abundance was also significantly associated with higher HDL-C levels in RYGB patients one year after surgery. Although dietary polyunsaturated fatty acid/saturated fatty acid (PUFA/SFA) ratio and PUFA intake were higher in controls than in AD subjects, of the four genera differentiated in cases and controls, only Akkermansia abundance showed a positive and significant correlation with PUFA/SFA ratio. Our results suggest that SCFA-producing bacteria promote a healthy lipid homeostasis, while the presence of LPS-producing bacteria such Escherichia-Shigella may contribute to the development of atherogenic dyslipidemia.

Neck circumference predicts development of carotid intima-media thickness and carotid plaque: A community-based longitudinal study

BACKGROUND AND AIMS

Carotid intima-media thickness (C-IMT) is an important index for evaluating subclinical atherosclerosis. Neck circumference (NC), a new anthropometric index of the upper body fat, is closely related to cardiovascular disease (CVD) and CVD risk factors. This study investigated the relationship between NC, C-IMT, and carotid plaque in a community-based cohort.

METHODS AND RESULTS

Participants recruited from Shanghai communities were followed up for 1.1-2.9 years. All participants underwent anthropometric and biochemical measurements. Elevated NC was defined as NC ≥ 38.5 cm and NC ≥ 34.5 cm in men and women, respectively. Elevated C-IMT, determined by ultrasound, was defined as a level higher than the 75th percentile in the study population (>0.75 mm). In total, 1189 participants without carotid plaque at baseline were included, with an average age of 59.6 ± 7.3 years. After a mean follow-up of 2.1 ± 0.2 years, 203 participants developed carotid plaques. After adjusting for various atherosclerosis risk factors, the logistic regression showed that the higher NC group had a significantly greater risk of developing carotid plaque than the lower NC group (odds ratio [OR], 1.55; 95% confidence interval [CI], 1.12-2.14; P = 0.008). Of those without carotid plaque at follow-up, 495 participants developed elevated C-IMT. Compared to the lower NC group, the higher NC group had a significantly increased risk of elevated C-IMT (OR, 1.49; 95% CI, 1.14-1.95; P = 0.003).

CONCLUSION

Higher NC was significantly positively correlated with the risk of carotid plaque and elevated C-IMT.

Vascular Calcification and the Gut and Blood Microbiome in Chronic Kidney Disease Patients on Peritoneal Dialysis: A Pilot Study

Vascular calcification (VC) is a frequent condition in chronic kidney disease (CKD) and a well-established risk factor for the development of cardiovascular disease (CVD). Gut dysbiosis may contribute to CVD and inflammation in CKD patients. Nonetheless, the role of gut and blood microbiomes in CKD-associated VC remains unknown. Therefore, this pilot study aimed to explore the link between gut and blood microbiomes and VC in CKD patients on peritoneal dialysis (CKD-PD). Our results showed relative changes in specific taxa between CKD-PD patients with and without VC, namely Coprobacter, Coprococcus 3, Lactobacillus, and Eubacterium eligens group in the gut, and Cutibacterium, Pajaroellobacter, Devosia, Hyphomicrobium, and Pelomonas in the blood. An association between VC and all-cause mortality risk in CKD-PD patients was also observed, and patients with higher mortality risk corroborate the changes of Eubacterium eligens in the gut and Devosia genus in the blood. Although we did not find differences in uremic toxins, intestinal translocation markers, and inflammatory parameters among CKD-PD patients with and without VC, soluble CD14 (sCD14), a nonspecific marker of monocyte activation, positively correlated with VC severity. Therefore, gut Eubacterium eligens group, blood Devosia, and circulating sCD14 should be further explored as biomarkers for VC, CVD, and mortality risk in CKD.

The Gut Microbial Signature of Gestational Diabetes Mellitus and the Association With Diet Intervention

Gestational diabetes mellitus (GDM) is a high-risk pregnancy complication that is associated with metabolic disorder phenotypes, such as abnormal blood glucose and obesity. The link between microbiota and diet management contributes to metabolic homeostasis in GDM. Therefore, it is crucial to understand the structure of the gut microbiota in GDM and to explore the effect of dietary management on the microbiota structure. In this study, we analyzed the composition of the gut microbiota between 27 GDM and 30 healthy subjects at two time points using Illumina HiSeq 2500 platform. The taxonomy analyses suggested that the overall bacteria clustered by diabetes status, rather than diet intervention. Of particular interest, the phylum Acidobacteria in GDM was significantly increased, and positively correlated with blood glucose levels. Moreover, Partial least-squares discriminant analysis (PLS-DA) revealed that certain genera in the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Lentisphaerae characterized the GDM gut microbiota. Correlation analysis indicated that blood glucose levels and BMI index were correlated with the relative abundance of SCFAS-producing genera. Through the comparison between the GDM and healthy samples with or without diet intervention, we discovered that the role of short-term diet management in GDM processes is associated with the change in the Firmicutes/Bacteroidetes ratio and some specific taxa, rather than an alternative gut microbial pattern. Our study have important implications for understanding the beneficial effects of diet intervention on the specific gut microbiota and thus possibly their metabolism in pregnant women with GDM.

Gut Microbiome Alterations in Patients With Visceral Obesity Based on Quantitative Computed Tomography

The gut microbiota is crucial in the pathogenesis of obesity. Abdominal obesity is known to significantly increase the risk of metabolic syndrome and cardiovascular disease, so further study is needed to investigate the changes of intestinal microorganisms in patients with excessive visceral fat. In our study, 41 people (n = 41) with normal body mass index (BMI) (18.5 ≤ BMI < 23.9) were included and divided into the low visceral fat area (L-VFA) group (n = 23, VFA < 100 cm²) and the high visceral fat area (H-VFA) group (n = 18, VFA ≥ 100 cm²). Several clinical indicators of the H-VFA group were significantly higher than those of the L-VFA group, including the waist circumference (WC), the fasting blood glucose (FBG), the triglyceride (TG), the total cholesterol (TC), the low-density lipoprotein cholesterol (LDL), the serum uric acid (SUA), the white blood cell count (WBC), the blood neutrophil count (NEC), and the blood lymphocyte count (LYC). Using whole-genome shotgun sequencing, we found that the types of the intestinal microbiota of H-VFA patients were different from those of the L-VFA patients, with 18 bacteria enriched in the H-VFA group and nine bacteria in the L-VFA group. A total of 16 species of gut microbes showed a strong correlation with VFA, and Escherichia coli has the strongest correlation, followed by Mitsuokella unclassified, Bifidobacterium longum, Escherichia unclassified, Ruminococcus torques, Dialister succinatiphilus, Eubacterium hallii, and Ruminococcus gnavus. Compared to the VFA, only two species show a strong correlation with BMI and WC. Further functional genetic studies suggested that the degradation of short-chain fatty acids (SCFAs) and the generation of lipopolysaccharide (LPS) might be related to visceral fat accumulation. Together, visceral fat was more closely correlated with the gut microbiome compared with BMI and WC. It suggested an intrinsic connection between the gut microbiome and visceral fat and its related metabolic disorders. Specific microbial species and pathways associated with visceral fat accumulation might contribute to new targeted therapies for visceral fat and its metabolic disorders.

Oolong tea extract alleviates weight gain in high-fat diet-induced obese rats by regulating lipid metabolism and modulating gut microbiota

Obesity is a serious global health issue and has become particularly prominent during the current COVID-19 pandemic. Tea is a traditional beverage in Asia and has been shown to provide...

Study on the differences of gut microbiota composition between phlegm-dampness syndrome and qi-yin deficiency syndrome in patients with metabolic syndrome

BACKGROUND

Metabolic syndrome (MS) is a group of complex medical conditions that can lead to serious cardiovascular and cerebrovascular diseases. According to the theory of traditional Chinese medicine (TCM), MS can be divided into two main subtypes termed 'phlegm-dampness syndrome' (TSZE) and 'qi-yin deficiency syndrome' (QYLX). At present, the research into intestinal microbiota of different TCM syndromes of MS and its association with clinical manifestation is lacking.

MATERIALS AND METHODS

Using 16S rRNA sequencing, we performed a cross-sectional analysis of human gut microbiota between two different TCM syndromes (QYLX and TSZE, n=60) of MS, and their differences with healthy participants (n=30).

RESULTS

We found that the QYLX and TSZE groups differ from the healthy control group in the overall gut microbiota composition, and some specific microbial taxa and functional pathways. Moreover, significantly differentially abundant taxa and distinct BMI-correlated taxa were observed between QYLX and TSZE groups, suggesting the potential contribution of gut microbiota to the distinction between the two TCM syndromes. The predicted functional profiles also showed considerable differences, especially pathways related to amino acid metabolism and lipopolysaccharide synthesis.

CONCLUSION

Our study highlights the gut microbiota's contribution to the differentiation between two TCM syndromes of MS and may provide the rationale for adopting different microbiota-directed treatment strategies for different TCM syndromes of MS in the future.

Impedance-based measures of muscle mass can be used to predict severity of hepatic steatosis in pediatric nonalcoholic fatty liver disease

OBJECTIVES

The objective of this study was to investigate the association between measures of body composition based on bioelectrical impedance analysis (BIA) and histologic severity of liver disease in a pediatric cohort with nonalcoholic fatty liver disease (NAFLD).

METHODS

This was a cross-sectional study of patients < 20 y old with histologically confirmed NAFLD followed in our Steatohepatitis Center from 2017 to 2019. Contemporaneous body-composition data were obtained using a multifrequency octopolar BIA device (InBody 370, InBody, Seoul, South Korea). BIA data collected were skeletal muscle mass, appendicular muscle mass, and percentage body fat. Skeletal and appendicular muscle mass were corrected for height (dividing by the square of height), generating their respective indices. Univariate linear and logistic regression, followed by multivariable logistic regression analyses, were used.

RESULTS

Of the 79 children included (27% female, 73% male; 38% Hispanic; median age, 13 y; median body mass index Z-score, 2.43), the median NAFLD Activity Score was 4 (interquartile range, 3-5). In multivariable regression analyses, the skeletal muscle mass index was negatively associated with hepatic steatosis after controlling for confounders (odds ratio, 0.76; 95% confidence interval, 0.62-0.93). Similarly, the appendicular muscle mass index was negatively associated with severity of hepatic steatosis severity (odds ratio, 0.69; 95% confidence interval, 0.53-0.90). In contrast, percentage body fat was not associated with hepatic steatosis. NAFLD Activity Score, lobular inflammation, ballooning scores, and fibrosis stage were not associated with measures of body composition.

CONCLUSIONS

There is an inverse association between BIA-based measures of muscle mass and severity of hepatic steatosis in children with NAFLD. BIA data could further inform clinical decision making in this context.

Protein supplementation during an energy-restricted diet induces visceral fat loss and gut microbiota amino acid metabolism activation: a randomized trial

Interactions between diet and gut microbiota are critical regulators of energy metabolism. The effects of fibre intake have been deeply studied but little is known about the impact of proteins. Here, we investigated the effects of high protein supplementation (Investigational Product, IP) in a double blind, randomised placebo-controled intervention study (NCT01755104) where 107 participants received the IP or an isocaloric normoproteic comparator (CP) alongside a mild caloric restriction. Gut microbiota profiles were explored in a patient subset (n = 53) using shotgun metagenomic sequencing. Visceral fat decreased in both groups (IP group: − 20.8 ± 23.2 cm²; CP group: − 14.5 ± 24.3 cm²) with a greater reduction (p < 0.05) with the IP supplementation in the Per Protocol population. Microbial diversity increased in individuals with a baseline low gene count (p < 0.05). The decrease in weight, fat mass and visceral fat mass significantly correlated with the increase in microbial diversity (p < 0.05). Protein supplementation had little effects on bacteria composition but major differences were seen at functional level. Protein supplementation stimulated bacterial amino acid metabolism (90% amino-acid synthesis functions enriched with IP versus 13% in CP group (p < 0.01)). Protein supplementation alongside a mild energy restriction induces visceral fat mass loss and an activation of gut microbiota amino-acid metabolism.

Clinical trial registration: NCT01755104 (24/12/2012). https://clinicaltrials.gov/ct2/show/record/NCT01755104?term=NCT01755104&draw=2&rank=1.

A Metagenome-Wide Association Study of the Gut Microbiome and Metabolic Syndrome

Metabolic syndrome (MetS) is a wide-ranging disorder, which includes insulin resistance, altered glucose and lipid metabolism, and increased blood pressure and visceral obesity. MetS symptoms combine to result in a significant increase in cardiovascular risk. It is therefore critical to treat MetS in the early stages of the disorder. In this study, 123 MetS patients and 304 controls were recruited to determine whether the gut microbiome plays a role in MetS development and progression. By using whole-genome shotgun sequencing, we found that the gut microbiomes of MetS patients were different from those of controls, with MetS patients possessing significantly lower gut microbiome diversity. In addition, 28 bacterial species were negatively correlated with waist circumstance, with Alistipes onderdonkii showing the strongest correlation, followed by Bacteroides thetaiotaomicron, Clostridium asparagiforme, Clostridium citroniae, Clostridium scindens, and Roseburia intestinalis. These species were also enriched in controls relative to MetS patients. In addition, pathways involved in the biosynthesis of carbohydrates, fatty acids, and lipids were enriched in the MetS group, indicating that microbial functions related to fermentation may play a role in MetS. We also found that microbiome changes in MetS patients may aggravate inflammation and contribute to MetS diseases by inhibiting the production of short-chain fatty acids (SCFAs). Taken together, these results indicate the potential utility of beneficial gut microbiota as a potential therapeutic to alleviate MetS.

Metabolic surgery in China: present and future

Obesity and its related complications comprise a serious public health problem worldwide, and obesity is increasing in China. Metabolic surgery is a new type of treatment with unique advantages in weight loss and obesity-related metabolic complications. The pathogenesis of obesity is complex and not yet fully understood. Here, we review the current efficacy and safety of metabolic surgery, as well as recent progress in mechanistic studies and surgical procedures in China. The exciting and rapid advances in this field provide new opportunities for patients with obesity and strike a balance between long-term effectiveness and safety.

Gut Microbiota of Chinese Obese Children and Adolescents With and Without Insulin Resistance

OBJECTIVE

The intestinal flora of gut microbiota in obese Chinese children and adolescents with and without insulin resistance (IR) was analyzed, as well as associations between the gut microbiota and two serum cytokines related to glucose metabolism, adropin and angiopoietin-like 4 (ANGPTL4).

METHODS

Clinical data, fecal bacterial composition, glucose-related hormones, and serum adipokines (adropin and ANGPTL4) were analyzed in 65 Chinese children with exogenous obesity. The composition of the gut microbiota was determined by 16S rRNA-based metagenomics and IR was calculated using the homeostasis model assessment (HOMA).

RESULTS

The 65 obese subjects were divided into two groups: insulin sensitive (IS) (n=40, 57.5% males) or IR (n=25, 60% males). Principal coordinates analysis revealed that the gut microbiota samples from the IS group clustered together and separated partly from the IR group (p=0.008). By Mann-Whitney U-test, at a phylum level, a reduction of Firmicutes and an increase of Bacteroidetes in the IR subjects was observed. LEfSe analysis revealed that IS subject, when compared to their IR counterparts, harbored members of the order Coriobacteriales, Turicibacterales, Pasteurellales and family Turicibacteraceae, that were significantly more abundant. In contrast, the IR subjects had members of family Peptococcaceae that were significantly more prevalent than the IS subjects (all p<0.05). Spearman's correlation analysis revealed that serum ANGPTL4 was positively associated with genus Bacteroides, Butyricimonas, and Alistipes, and adropin was positively associated with genus Anaerostipes and Alistipes, and negatively associated with genus Blautia (all p<0.05).

CONCLUSION

In obese children, the gut microbiome in IR subjects was significantly discordant from the IS subjects, and the abundance of some metabolism-related bacteria correlated with the serum concentrations of adropin and ANGPTL4. These observations infer that the gut microbiota may be involved in the regulation of glucose metabolism in obesity.