Mapping the human oral and gut fungal microbiota in patients with metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated steatotic liver disease and the gut microbiome: pathogenic insights and therapeutic innovations

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major cause of liver disease worldwide, and our understanding of its pathogenesis continues to evolve. MASLD progresses from steatosis to steatohepatitis, fibrosis, and cirrhosis, and this Review explores how the gut microbiome and their metabolites contribute to MASLD pathogenesis. We explore the complexity and importance of the intestinal barrier function and how disruptions of the intestinal barrier and dysbiosis work in concert to promote the onset and progression of MASLD. The Review focuses on specific bacterial, viral, and fungal communities that impact the trajectory of MASLD and how specific metabolites (including ethanol, bile acids, short chain fatty acids, and other metabolites) contribute to disease pathogenesis. Finally, we underscore how knowledge of the interaction between gut microbes and the intestinal barrier may be leveraged for MASLD microbial-based therapeutics. Here, we include a discussion of the therapeutic potential of prebiotics, probiotics, postbiotics, and microbial-derived metabolites.

Intervention effects of Er Miao san on metabolic syndrome in Bama miniature pigs

BACKGROUND

Metabolic syndrome (MS) refers to a cluster of metabolic disorders characterized by systemic chronic inflammation. Er Miao San (EMS) is a classic traditional Chinese medicine compound containing Phellodendron amurense and Atractylodis rhizome at a ratio of 1:1, proven to be effective against inflammatory diseases in clinical practice. Nevertheless, the precise functions of EMS in treating MS and its underlying mechanism have yet to be elucidated.

PURPOSE

This study focuses on the intervention effects of EMS on high humidity exposure and high sugar-fat diet (HHSF)-induced MS in pigs.

STUDY DESIGN

Blood biochemical indices and metabolome analysis were employed to confirm the successful establishment of the MS model, and the preliminary evaluation of the intervention effect of EMS was conducted. Subsequently, a parallel microbiota analysis of the tongue and cecum was combined with metabolomic analysis, histopathologic examination, and other molecular biological detection to further assess the administration mechanism of EMS.

RESULTS

The results demonstrated that EMS significantly reduced the excessive weight gain rate, fat accumulation, hyperlipidemia, hyperglycemia, and systemic inflammation while improving serum metabolic disorder in MS pigs. Moreover, microbiota analysis indicates that EMS restored the diversity and composition of oral-gut microbiota by increasing the proportions of Lactobacillus (gut), Roseburia (gut), Faecalibacterium (gut), CF231 (gut), Streptococcus (gut), Prevotella (gut), while decreasing those of Chryseobacterium (oral), Corynebacterium (oral), Clostridium (oral), Oscillospira (gut), and Turicibacter (oral, gut). Subsequently, EMS up-regulated the concentrations of acetic acid, butyric acid, propionic acid, while down-regulated isobutyric acid and isovaleric acid. This resulted in a suppression of HDAC3 expression and an increase of SCL16A1 expression in the colon. Notably, the changes in acetic acid and butyric acid showed a strong correlation with gut microbiota. Additionally, EMS reduced the serum level of lipopolysaccharide (LPS) and enhanced epithelial barrier integrity by inhibiting the LPS-TLR4/MyD88/NF-κB pathways.

CONCLUSIONS

EMS was found to ameliorate MS by alleviating the dysbiosis of the oral-gut microbiota and serum metabolome, thereby improving gut barrier and reducing systemic inflammation. These findings suggest that EMS holds promise as a therapeutic agent for MS.

Gut microbiome and NAFLD: impact and therapeutic potential

Non-Alcoholic Fatty Liver Disease (NAFLD) affects approximately 32.4% of the global population and poses a significant health concern. Emerging evidence underscores the pivotal role of the gut microbiota-including bacteria, viruses, fungi, and parasites-in the development and progression of NAFLD. Dysbiosis among gut bacteria alters key biological pathways that contribute to liver fat accumulation and inflammation. The gut virome, comprising bacteriophages and eukaryotic viruses, significantly shapes microbial community dynamics and impacts host metabolism through complex interactions. Similarly, gut fungi maintain a symbiotic relationship with bacteria; the relationship between gut fungi and bacteria is crucial for overall host health, with certain fungal species such as Candida in NAFLD patients showing detrimental associations with metabolic markers and liver function. Additionally, the "hygiene hypothesis" suggests that reduced exposure to gut parasites may affect immune regulation and metabolic processes, potentially influencing conditions like obesity and insulin resistance. This review synthesizes current knowledge on the intricate interactions within the gut microbiota and their associations with NAFLD. We highlight the therapeutic potential of targeting these microbial communities through interventions such as probiotics, prebiotics, and fecal microbiota transplantation. Addressing the complexities of NAFLD requires comprehensive strategies that consider the multifaceted roles of gut microorganisms in disease pathology.

The oral-gut microbiome axis in breast cancer: from basic research to therapeutic applications

As a complicated and heterogeneous condition, breast cancer (BC) has posed a tremendous public health challenge across the world. Recent studies have uncovered the crucial effect of human microbiota on various perspectives of health and disease, which include cancer. The oral-gut microbiome axis, particularly, have been implicated in the occurrence and development of colorectal cancer through their intricate interactions with host immune system and modulation of systemic inflammation. However, the research concerning the impact of oral-gut microbiome axis on BC remains scarce. This study focused on comprehensively reviewing and summarizing the latest ideas about the potential bidirectional relation of the gut with oral microbiota in BC, emphasizing their potential impact on tumorigenesis, treatment response, and overall patient outcomes. This review can reveal the prospect of tumor microecology and propose a novel viewpoint that the oral-gut microbiome axis can be a breakthrough point in future BC studies.

Advances in the study of oral microbiota and metabolism associated fatty liver disease: a systematic review

Objective

The oral microbiota is the second largest microbiota in the human body and has a significant impact on human health. Recent evidence suggests that dysbiosis of the oral microbiota may be associated with the development of metabolism-associated fatty liver disease (MAFLD). This review aimed to validate the relationship between oral microbial diversity and the development of MAFLD.

Methods

A systematic evaluation was performed based on PRISMA guidelines. Three independent reviewers searched for relevant literature in several databases, including PubMed/Medline, Web of Science, and Scopus, with a search date ranging from the establishment of the databases to June 2024.

Results

A total of 1278 publications were initially screened, including five cross-sectional studies, seven case-control studies, one cohort study, and one retrospective study. These studies included a total of 3335 patients with MAFLD, 254 patients with MASH, and 105 patients with liver cirrhosis. All 14 included studies concluded that there was a correlation or potential correlation between oral microbiota and MAFLD. Seven studies found that the composition of the oral microbiota in MAFLD patients differed from that of healthy controls, and specific oral bacteria may be associated with an increased incidence of MAFLD. At the phylum level, several studies found differences in the abundance of the phyla Firmicutes, Proteobacteria, and Clostridia compared to healthy controls. Additionally, a study on oral fungi found significant differences in the phyla Proteobacteria and in the genus Staphylococcus between patients with MAFLD and healthy controls. At the genus level, Porphyromonas was studied most frequently, with all 8 studies identifying infection with Porphyromonas as a significant risk factor for pathological progression in MAFLD. Furthermore, a dysbiosis in the ratio of Porphyromonas gingivalis./Porphyromonas anomalies may be an important marker of MAFLD progression.

Conclusion

There is an important association between the diversity of oral microbiota composition and MAFLD. This finding suggests the importance of oral health assessment and monitoring for the prevention or intervention of MAFLD.

Can salivary and skin microbiome become a biodetector for aging-associated diseases? Current insights and future perspectives

Growth and aging are fundamental elements of human development. Aging is defined by a decrease in physiological activities and higher illness vulnerability. Affected by lifestyle, environmental, and hereditary elements, aging results in disorders including cardiovascular, musculoskeletal, and neurological diseases, which accounted for 16.1 million worldwide deaths in 2019. Stress-induced cellular senescence, caused by DNA damage, can reduce tissue regeneration and repair, promoting aging. The root cause of many age-related disorders is inflammation, encouraged by the senescence-associated secretory phenotype (SASP). Aging's metabolic changes and declining immune systems raise illness risk via promoting microbiome diversity. Stable, individual-specific skin and oral microbiomes are essential for both health and disease since dysbiosis is linked with periodontitis and eczema. Present from birth to death, the human microbiome, under the influence of diet and lifestyle, interacts symbiotically with the body. Poor dental health has been linked to Alzheimer's and Parkinson's diseases since oral microorganisms and systemic diseases have important interactions. Emphasizing the importance of microbiome health across the lifetime, this study reviews the understanding of the microbiome's role in aging-related diseases that can direct novel diagnosis and treatment approaches.

Gut mycobiome alterations and implications for liver diseases

Chronic liver disease and its complications are a significant global health burden. Changes in fungal communities (mycobiome), an integral component of the gut microbiome, are associated with and contribute to the development of liver disease. Fungal dysbiosis can induce intestinal barrier dysfunction and allow fungal products to translocate to the liver causing progression of disease. This review explores recent progress in understanding the compositional and functional diversity of gut mycobiome signatures across different liver diseases. It delves into causative connections between gut fungi and liver diseases. We emphasize the significance of fungal translocation, with a particular focus on fungal-derived metabolites and immune cells induced by fungi, as key contributors to liver disease. Furthermore, we review the potential impact of the intrahepatic mycobiome on the progression of liver diseases.

A pilot study on the characterization and correlation of oropharyngeal and intestinal microbiota in children with type 1 diabetes mellitus

Background

Type 1 Diabetes Mellitus (T1DM) is one of the most common endocrine disorders of childhood and adolescence, showing a rapidly increasing prevalence worldwide. A study indicated that the composition of the oropharyngeal and gut microbiota changed in T1DM. However, no studies have yet associated the changes between the microbiomes of the oropharyngeal and intestinal sites, nor between the flora and clinical indicators. In this study, we examined the composition and characteristics of oropharyngeal and intestinal flora in patients with T1DM in compared to healthy children. We identified correlations between oropharyngeal and intestinal flora and evaluated their association with clinical laboratory tests in patients with T1DM.

Methods

The oropharyngeal and fecal samples from 13 T1DM and 20 healthy children were analyzed by high-throughput sequencing of the V3-V4 region of 16S rRNA. The associations between microbes and microorganisms in oropharyngeal and fecal ecological niches, as well as the correlation between these and clinical indicators were further analyzed.

Results

It was revealed that T1DM children had distinct microbiological characteristics, and the dominant oropharyngeal microbiota genus included Streptococcus, Prevotella, Leptotrichia, and Neisseria; that of intestinal microbiota included Blautia, Fusicatenibacter, Bacteroides, and Eubacterium_hallii_group. Furthermore, oropharyngeal Staphylococcus was significantly positively correlated with intestinal norank_f__Ruminococcaceae and Ruminococcus_torques_group in TIDM children. Moreover, in these children, differential genes in oropharyngeal and intestinal samples were enriched in metabolic pathways such as amino acid generation, fatty acid metabolism, and nucleotide sugar biosynthesis. Additionally, correlation analysis between the oropharyngeal/intestinal microbiome with laboratory tests showed significant correlations between several bacterial taxa in the oropharynx and intestines and glycated hemoglobin and C-peptide.

Conclusion

Unique microbial characteristics were found in the oropharynx and intestine in children with T1DM compared to healthy children. Positive correlations were found between changes in the relative abundance of oropharyngeal and gut microbiota in children with T1DM. Associations between the oropharyngeal/intestinal microbiota and laboratory investigations in children with T1DM suggest that the composition of the oropharyngeal and intestinal flora in children with T1DM may have some impact on glycemic control.

Oral Mycobiota: A Narrative Review

Numerous studies have proven the important role of the oral microbiota in health and disease. The dysfunctionality of the oral microbiota, known as dysbiosis, is incriminated in dental caries, periodontal disease, oral infectious diseases, oral cancer, and systemic disease. The lesser-known component of the oral microbiota, the mycobiota, is now assiduously investigated. Recent technological developments have helped foster the identification of new fungal species based on genomic research. Next-generation sequencing has expanded our knowledge about the diversity, architecture, and relationships of oral microorganisms within the oral cavity. The mycobiome structure and relationships with the bacteriome have been studied to identify a mycobiotic signature. This review aimed to emphasize the latest knowledge of the oral mycobiome.

Application of intelligent tongue image analysis in Conjunction with microbiomes in the diagnosis of MAFLD

Background

Metabolic associated fatty liver disease (MAFLD) is a widespread liver disease that can lead to liver fibrosis and cirrhosis. Therefore, it is essential to develop early diagnosic and screening methods.

Methods

We performed a cross-sectional observational study. In this study, based on data from 92 patients with MAFLD and 74 healthy individuals, we observed the characteristics of tongue images, tongue coating and intestinal flora. A generative adversarial network was used to extract tongue image features, and 16S rRNA sequencing was performed using the tongue coating and intestinal flora. We then applied tongue image analysis technology combined with microbiome technology to obtain an MAFLD early screening model with higher accuracy. In addition, we compared different modelling methods, including Extreme Gradient Boosting (XGBoost), random forest, neural networks(MLP), stochastic gradient descent(SGD), and support vector machine(SVM).

Results

The results show that tongue-coating Streptococcus and Rothia, intestinal Blautia, and Streptococcus are potential biomarkers for MAFLD. The diagnostic model jointly incorporating tongue image features, basic information (gender, age, BMI), and tongue coating marker flora (Streptococcus, Rothia), can have an accuracy of 96.39%, higher than the accuracy value except for bacteria.

Conclusion

Combining computer-intelligent tongue diagnosis with microbiome technology enhances MAFLD diagnostic accuracy and provides a convenient early screening reference.

Role of gut microbiota on regulation potential of Dendrobium officinale Kimura & Migo in metabolic syndrome: In-vitro fermentation screening and in-vivo verification in db/db mice

ETHNOPHARMACOLOGICAL RELEVANCE

Dendrobium officinale Kimura & Migo (DEN) is a traditional medicine in China since Han dynasty. Decoction of its stem is often used in the treatment of Type-II diabetes (T2D), which is a typical metabolic disease accompanied with the impaired metabolic function of blood glucose and lipid.

AIM OF THE STUDY

Our study aimed to investigate the role of gut microbiota in differentiating DEN from different sources and its related pathway in the alleviation of metabolic syndromes induced by T2D.

MATERIALS AND METHODS

The aqueous extracts of four commercially available Dendrobium (DEN-1∼4) were prepared and screened through an in-vitro fermentation system. Based on their alterations in monosaccharide composition and short chain fatty acids (SCFA) formation during fermentation with db/db faecal fluid, one DEN extract was selected for further in vivo verification. The selected Dendrobium (DEN-4) was orally administered to db/db mice for 16 days once daily at the dosage of 200 mg/kg followed by evaluating its effect on blood glucose level, liver function and intestinal microenvironment including alterations of intestinal integrity and gut microbiota composition. In addition, liver metabolomics analysis was employed to reveal the related metabolic pathways.

RESULTS

Different extent of SCFA formation and utilization of monosaccharides were observed for the extracts of four DEN from different sources with a negative correlation between SCFA level and the ratio of Utilized glucose/Utilized mannose observed in the in-vitro fermentation system with db/db faecal fluid. DEN-4 with the highest SCFA formation during the in-vitro fermentation was selected and exhibited significantly hypoglycaemic effect in db/db mice with the alleviation of hepatic steatosis and impaired lipid homeostasis. Further mechanistic studies revealed that orally administered DEN-4 could improve the intestinal integrity of db/db mice via elevating their tight junction protein (ZO-1 and Occludin) expression in the colon and improve the diversity of gut microbiota with enhanced formation of SCFA. Moreover, metabolomics and KEGG pathway analysis of liver tissues suggested that the alleviated metabolic syndrome in db/db mice by DEN-4 might possibly be achieved through activation of PPAR pathway.

CONCLUSION

Our current study not only revealed the potential of gut microbiota in differentiating DEN from different sources, but also demonstrated that DEN exhibited its beneficial effect on the T2D induced metabolic syndrome possibly through enhancement of intestinal integrity and activation of PPAR pathway via gut-liver axis in db/db mice.