Evidence for the contribution of the gut microbiome to obesity and its reversal

Gut microbiota diversity in obese rats treated with intermittent fasting, probiotic-fermented camel milk with or without dates and their combinations

Dietary alternatives help effectively in obesity management. The present study examines the gut microbiota diversity in obesity-induced rats treated with intermittent fasting, fermented camel milk (FCM), and FCM-incorporated Sukkari date or their combinations. The metagenomic analysis of the gut microbiome through 16 S rRNA revealed 226 families, 499 genera, and 879 bacterial species. In the taxonomy distributions and heatmap analysis, Bacteroidota (i.e., Prevotella) had the uppermost relative abundance in groups before treatments (Before_Groups, most samples clustered in one sub-cluster) reached 80.50% in sample S11 (Before_G2), whereas Firmicutes (i.e., Lactobacillus) presented the dominant in groups after treatments (After_Groups, generality samples grouped in another sub-cluster) and counted 70.86% in sample S88 (After_G6), reflecting potential short-chain fatty acids production. The alpha and beta diversity explored by Shannon and PCoA indices presented high diversity in most groups after treatment. Deferribacterota and Fusobacteriota, in addition to Stenotrophomonas and Listeria, were the key phylotypes in the treated groups at the Phylum and genus levels, respectively. The proposed functional pathways involving mannan, rhamnose I, glucose, and xylose degradation were the most supported pathways in After_Groups with potential carbohydrate degradation. Eventually, intermittent fasting and probiotic fermented camel milk increased microbiome diversity and accelerated weight loss, preventing health issues.

Next Steps in Efforts to Address the Obesity Epidemic

Obesity prevalence continues to rise globally at alarming rates, with adverse health and economic implications. In this state-of-the-art review, we provide an analysis of selected evidence about the current knowledge in the obesity literature, including a synthesis of current challenges in obesity and its determinants. In addition, we review past and current efforts to combat the obesity epidemic, highlighting both successful efforts and areas for further development. Last, we offer insights into the next steps to address the obesity epidemic and advance the field of obesity through both research and practice by (a) adopting a systems perspective, (b) fostering cross-sector and community collaborations, (c) advancing health equity, (d) narrowing the research-to-practice and research-to-policy gaps with multidisciplinary approaches, and (e) embracing complementary approaches for concurrent obesity prevention and treatment.

Potential of queen bee larvae as a dietary supplement for obesity management: modulating the gut microbiota and promoting liver lipid metabolism

Queen bee larvae (QBL) have been consumed as both a traditional food and medicine in China for thousands of years; however, their specific benefits for human health, particularly their potential anti-obesity property, remain underexplored. This study investigated the anti-obesity effect of QBL freeze-dried powder (QBLF) on high-fat diet (HFD) induced obesity in mice and explored the underlying mechanisms. Our findings showed that QBLF effectively reduced body weight, fasting blood glucose levels, lipid accumulation, and inflammation in HFD mice. 16S rRNA sequencing revealed that QBLF significantly modulated the gut microbiota disrupted by an HFD, notably increasing the relative abundance of beneficial microbes such as Ileibacterium, Clostridium sensu stricto 1, Incertae sedis, Streptococcus, Lactococcus, Clostridia UCG-014, and Lachnospiraceae UCG-006, which were inversely associated with obesity-related phenotypes in the mice. RNA sequencing analysis further demonstrated that QBLF intervention upregulated the expression of genes involved in liver lipid metabolism, including Pck1, Cyp4a10, Cyp4a14, and G6pc, while downregulating genes associated with the inflammatory response, such as Cxcl10, Ccl2, Traf1, Mapk15, Lcn2, and Fosb. These results suggested that QBLF can ameliorate HFD-induced obesity through regulating the gut microbiota, promoting liver lipid metabolism, and reducing inflammatory response.

The microbiome's influence on obesity: mechanisms and therapeutic potential

In 2023, the World Obesity Atlas Federation concluded that more than 50% of the world's population would be overweight or obese within the next 12 years. At the heart of this epidemic lies the gut microbiota, a complex ecosystem that profoundly influences obesity-related metabolic health. Its multifaced role encompasses energy harvesting, inflammation, satiety signaling, gut barrier function, gut-brain communication, and adipose tissue homeostasis. Recognizing the complexities of the cross-talk between host physiology and gut microbiota is crucial for developing cutting-edge, microbiome-targeted therapies to address the global obesity crisis and its alarming health and economic repercussions. This narrative review analyzed the current state of knowledge, illuminating emerging research areas and their implications for leveraging gut microbial manipulations as therapeutic strategies to prevent and treat obesity and related disorders in humans. By elucidating the complex relationship between gut microflora and obesity, we aim to contribute to the growing body of knowledge underpinning this critical field, potentially paving the way for novel interventions to combat the worldwide obesity epidemic.

The relationship between dietary index for gut microbiota and diabetes

This study aims to explore the relationship between the Dietary Index for Gut Microbiota (DI-GM) and diabetes. In recent years, there has been increasing attention to the role of the gut microbiome in regulating host metabolism. However, the relationship between DI-GM and the risk of diabetes has not been sufficiently studied. This study utilized relevant data from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. Multiple logistic regression analysis was conducted to explore the relationship between DI-GM and the risk of diabetes. The dose-response relationship between DI-GM and the risk of diabetes was observed using restricted cubic splines (RCS). Threshold effect analysis was performed based on RCS results. Subgroup analyses were used to conduct a sensitivity analysis of the relationship between DI-GM and the risk of diabetes. The results from multiple logistic regression analysis indicated a significant negative correlation between DI-GM and the risk of diabetes (OR, 0.954, 95%CI, 0.918-0.991). RCS results also showed a significant nonlinear negative relationship between DI-GM and the risk of diabetes (P < 0.001, P for nonlinear = 0.010). The threshold effect analysis revealed that when DI-GM was below 6.191, there was a significant negative correlation between DI-GM and the risk of diabetes (OR, 0.921, 95% CI, 0.876-0.969). However, when DI-GM exceeded 6.191, the relationship between DI-GM and the risk of diabetes was no longer significant. Subgroup analysis revealed that the negative correlation between DI-GM and the risk of diabetes remained significant in Whites, participants with a poverty-income ratio > 3.5, body mass index > 24, current drinkers, never or current smokers, and those without chronic kidney disease (P < 0.05). This study demonstrates a nonlinear negative correlation between DI-GM and the risk of diabetes. Maintaining DI-GM above 6.191 may help prevent diabetes.

High-dose thiamine supplementation ameliorates obesity induced by a high-fat and high-fructose diet in mice by reshaping gut microbiota

Introduction

Thiamine (vitamin B1) in the gut is crucial for maintaining intestinal homeostasis and host health. Our previous study identified significantly lower levels of fecal thiamine in individuals with obesity; however, its potential and mechanisms for alleviating obesity induced by a high-fat and high-fructose diet (HFFD) remain unclear. Therefore, in the present study, the effects of high-dose thiamine supplementation on HFFD-induced obesity and gut microbiota dysbiosis were investigated.

Methods

HFFD-fed mice were supplemented with high-dose thiamine for eight weeks. Biochemical analysis and histological analysis were conducted to assess phenotypic changes. Fecal 16S rRNA gene sequencing was performed to analyze alterations in the gut microbiota.

Results

The results showed that high-dose thiamine supplementation for eight weeks could significantly alleviate symptoms of HFFD-induced obesity and improve HFFD-induced intestinal epithelial barrier dysfunction by enhancing the tight junction function. Furthermore, oral administration of high-dose thiamine also regulated HFFD-induced gut microbiota dysbiosis by reshaping its structure and composition of gut microbiota, such as increasing the relative abundance of Actinobacteria and Bifidobacterium pseudolongum, and reducing the relative abundance of Proteobacteria and Ruminococcus gnavus, accompanied by decreased level of gut-derived endotoxin. Finally, significant correlations were found between obesity-related phenotypes and gut microbiota through correlation analysis.

Conclusion

Our findings suggest that the potential mechanism by which high-dose thiamine supplementation alleviated HFFD-induced obesity might involve reshaping gut microbiota and restoring the intestinal barrier, thereby ameliorating gut microbiota-related endotoxemia.

Association between a body shape index and colorectal cancer in US population: a cross-sectional study based on NHANES

Background

Colorectal cancer (CRC) is linked to obesity, particularly visceral fat. A more accurate measure of visceral fat accumulation is offered by a body shape index (ABSI). Currently, the direct application of the ABSI to populations with varying ethnic backgrounds might be restricted. Moreover, there is less evidence about the correlation between ABSI and CRC among individuals from different ethnical backgrounds.

Methods

A total of 40,998 individuals who took part in the National Health and Nutrition Examination Survey (NHANES) spanning from 2003 to 2023 were subjected to analysis. Logistic regression was utilized to examine the associations between the ABSI and the risk of CRC. In addition, restricted cubic spline curves (RCS) were utilized, and subgroup analyses along with interaction tests were also carried out. The receiver operating characteristic curve (ROC) was employed to predict the risk of CRC relying on various anthropometric indicators.

Results

After adjusting for covariates, ABSI demonstrated a positive association with the incidence of CRC (OR = 1.03 [95% CI: 1.01-1.05], p = 0.018). Individuals in the upper quartile of ABSI exhibited a greater prevalence of CRC than those in the lower quartile (OR = 1.88 [95% CI: 1.19-2.96], p = 0.006). RCS analysis indicated a nonlinear correlation between ABSI and CRC (P for nonlinear = 0.030). Subgroup analysis indicated a notable interaction between age and BMI subgroups (interaction p < 0.05), and ROC curves indicated that the ABSI was effective in predicting CRC risk (AUC = 0.658), demonstrating good sensitivity, particularly in individuals under 60 years of age.

Conclusion

A positive correlation exists between ABSI levels and the increased incidence of CRC among U.S. adults. This is especially true for people under 60 years of age (40-60 years), with a BMI below 25 kg/m2, and those with a BMI of 30 kg/m2 or beyond. ABSI can be used as a simple anthropometric predictor of CRC.

Revisiting the role of IL-27 in obesity-related metabolic diseases: safeguard or perturbation?

The prevalence of metabolic diseases, such as obesity, has been steadily increasing in recent years, posing a significant threat to public health. Therefore, early identification and intervention play a crucial role. With the deepening understanding of the etiology of metabolic diseases, novel therapeutic targets are emerging for the treatment of obesity, lipid metabolism disorders, cardiovascular and cerebrovascular diseases, glucose metabolism disorders, and other related metabolic conditions. IL-27, as a multi-potent cytokine, holds great promise as a potential candidate target in this regard. This article provides a comprehensive review of the latest findings on IL-27 expression and signal transduction in the regulation of immune inflammatory cells, as well as its implications in obesity and other related metabolic diseases. Furthermore, it explores the potential of IL-27 as a novel therapeutic target for the treatment of obesity and metabolic disorders. Finally, an overview is presented on both the opportunities and challenges associated with targeting IL-27 for therapeutic interventions.

Investigating the uncertain causal link between gut microbiota and glaucoma: A genetic correlation and Mendelian randomisation study

BACKGROUND

Glaucoma is the most common cause of irreversible blindness, and gut microbiota (GM) is associated with glaucoma. Whether this association represents a causal role remains unknown. This study aims to assess the potential association and causal link between GM and various forms of glaucoma, emphasising the need for cautious interpretation of the strength of these associations.

METHODS

Employing a two-sample bidirectional Mendelian randomisation (MR) framework with false discovery rate correction and various sensitivity analyses, supplemented by genetic correlation analysis via linkage disequilibrium score regression (LDSC) and colocalisation for European summary-level data between MiBioGen consortium and FinnGen Study, we sought to explore the relationship between GM and glaucoma.

RESULTS

While certain microbial taxa showed potential associations with glaucoma subtypes (e.g., Erysipelotrichaceae with primary angle closure glaucoma, Senegalimassilia with exfoliation glaucoma), the overall findings suggest a complex and not definitively causal relationship between GM and glaucoma. Notably, reverse MR analysis did not establish a significant causal effect of glaucoma on GM composition, and no consistent genetic correlations were observed between GM and glaucoma.

CONCLUSIONS

While our study provides some evidence of associations between specific GM taxa and glaucoma, the results underscore the complexity of these relationships and the need for further research to clarify the potential causal links. The findings highlight the importance of interpreting the gut-eye axis with caution and suggest that while GM may play a role in glaucoma, it is unlikely to be a predominant causal factor.

The interplay of gut microbiota, obesity, and depression: insights and interventions

The gut microbiome, body weight, and related comorbidities are intricately linked through a complex interaction of microbial, genetic, environmental, and psychological factors. Alterations in gut microbiota can contribute to the development of weight disorders and depressive symptoms, with the potential for these relationships to be bidirectional. Effective management of these interconnected conditions often involves a combination of lifestyle modifications and psychological support. Medical interventions, including treatments for obesity, antidiabetic drugs, antidepressants, antibiotics, and probiotics, can have beneficial and detrimental effects on gut microbiota and mental health. Further research is needed to better understand their impact on gut microbiome and mental health in the context of obesity.

The relationship between body roundness index and depression: A cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) 2011-2018

BACKGROUND

Depression is linked to obesity. The body roundness index (BRI) provides a more accurate assessment of body and visceral fat levels than the body mass index or waist circumference. However, the association between BRI and depression is unclear. Therefore, we investigated this relationship using the National Health and Nutrition Examination Survey (NHANES) database.

METHODS

In this population-based cross-sectional study, data from 18,654 adults aged ≥20 years from the NHANES 2011-2018 were analyzed. Covariates, including age, gender, race/ethnicity, education level, marital status, poverty-income ratio, alcohol status, smoking status, hypertension, diabetes mellitus, cardiovascular disease, energy intake, physical activity, total cholesterol, and triglycerides were adjusted in multivariable logistic regression models. In addition, smooth curve fitting, subgroup analysis, and interaction testing were conducted.

RESULTS

After adjusting for covariates, BRI was positively correlated with depression. For each one-unit increase in BRI, the prevalence of depression increased by 8 % (odds ratio = 1.08, 95 % confidence interval = 1.05-1.10, P < 0.001).

LIMITATIONS

As this was a cross-sectional study, we could not determine a causal relationship between BRI and depression. Patients with depression in this study were not clinically diagnosed with major depressive disorder.

CONCLUSION

BRI levels were positively related to an increased prevalence of depression in American adults. BRI may serve as a simple anthropometric index to predict depression.

RiboSnake - a user-friendly, robust, reproducible, multipurpose and documentation-extensive pipeline for 16S rRNA gene microbiome analysis

Background

Next-generation sequencing for microbial communities has become a standard technique. However, the computational analysis remains resource-intensive. With declining costs and growing adoption of sequencing-based methods in many fields, validated, fully automated, reproducible and flexible pipelines are increasingly essential in various scientific fields.

Results

We present RiboSnake, a validated, automated, reproducible QIIME2-based pipeline implemented in Snakemake for analysing 16S rRNA gene amplicon sequencing data. RiboSnake includes pre-packaged validated parameter sets optimized for different sample types, from environmental samples to patient data. The configuration packages can be easily adapted and shared, requiring minimal user input.

Conclusion

RiboSnake is a new alternative for researchers employing 16S rRNA gene amplicon sequencing and looking for a customizable and user-friendly pipeline for microbiome analyses with in vitro validated settings. By automating the analysis with validated parameters for diverse sample types, RiboSnake enhances existing methods significantly. The workflow repository can be found on GitHub (https://github.com/IKIM-Essen/RiboSnake).

The Gut Microbial Regulation of Epigenetic Modification from a Metabolic Perspective

Obesity is a global health challenge that has received increasing attention in contemporary research. The gut microbiota has been implicated in the development of obesity, primarily through its involvement in regulating various host metabolic processes. Recent research suggests that epigenetic modifications may serve as crucial pathways through which the gut microbiota and its metabolites contribute to the pathogenesis of obesity and other metabolic disorders. Hence, understanding the interplay between gut microbiota and epigenetic mechanisms is crucial for elucidating the impact of obesity on the host. This review primarily focuses on the understanding of the relationship between the gut microbiota and its metabolites with epigenetic mechanisms in several obesity-related pathogenic mechanisms, including energy dysregulation, metabolic inflammation, and maternal inheritance. These findings could serve as novel therapeutic targets for probiotics, prebiotics, and fecal microbiota transplantation tools in treating metabolic disruptions. It may also aid in developing therapeutic strategies that modulate the gut microbiota, thereby regulating the metabolic characteristics of obesity.

Quantitative and dynamic profiling of human gut core microbiota by real-time PCR

The human gut microbiota refers to a diverse community of microorganisms that symbiotically exist in the human intestinal system. Altered microbial communities have been linked to many human pathologies. However, there is a lack of rapid and efficient methods to assess gut microbiota signatures in practice. To address this, we established an appraisal system containing 45 quantitative real-time polymerase chain reaction (qPCR) assays targeting gut core microbes with high prevalence and/or abundance in the population. Through comparative genomic analysis, we selected novel species-specific genetic markers and primers for 31 of the 45 core microbes with no previously reported specific primers or whose primers needed improvement in specificity. We comprehensively evaluated the performance of the qPCR assays and demonstrated that they showed good sensitivity, selectivity, and quantitative linearity for each target. The limit of detection ranged from 0.1 to 1.0 pg/µL for the genomic DNA of these targets. We also demonstrated the high consistency (Pearson's r = 0.8688, P < 0.0001) between the qPCR method and metagenomics next-generation sequencing (mNGS) method in analyzing the abundance of selected bacteria in 22 human fecal samples. Moreover, we quantified the dynamic changes (over 8 weeks) of these core microbes in 14 individuals using qPCR, and considerable stability was demonstrated in most participants, albeit with significant individual differences. Overall, this study enables the simple and rapid quantification of 45 core microbes in the human gut, providing a promising tool to understand the role of gut core microbiota in human health and disease. KEY POINTS: • A panel of original qPCR assays was developed to quantify human gut core microbes. • The qPCR assays were evaluated and compared with mNGS using real fecal samples. • This method was used to dynamically profile the gut core microbiota in individuals.

Approaches to teaching about mechanisms of obesity in undergraduate pathophysiology courses

Views of obesity as a consequence of "lack of willpower" or other behavioral choices, rather than a complex array of biological and other factors, are quite common among undergraduate students. Many undergraduates in prenursing or biology programs have little exposure to the physiology and pathophysiology of obesity, including learning about leptin and other hormones involved in appetite control. I developed materials for teaching about the pathophysiology of obesity in two different pathophysiology courses: one designed as a survey of pathophysiology topics for prenursing majors, and the other designed as an in-depth exploration of the molecular and cellular basis of selected diseases for upper-division biology majors. In the molecular basis of disease course, obesity is covered as part of a unit organized around metabolic syndrome. The discussion includes molecular and cellular mechanisms that link obesity to several other diseases, including type 2 diabetes and atherosclerosis. This article briefly describes the approaches I have taken for teaching obesity to two different undergraduate student populations and lists several resources that may be useful tools for teaching about obesity.NEW & NOTEWORTHY This article describes approaches for teaching obesity in an allied health major pathophysiology course, and, additionally, in an upper-division biology major course on the cellular and molecular basis of disease.