Effects of Christensenella minuta lipopolysaccharide on RAW 264.7 macrophages activation

Achieving healthy aging through gut microbiota-directed dietary intervention: Focusing on microbial biomarkers and host mechanisms

BACKGROUND

Population aging has become a primary global public health issue, and the prevention of age-associated diseases and prolonging healthy life expectancies are of particular importance. Gut microbiota has emerged as a novel target in various host physiological disorders including aging. Comprehensive understanding on changes of gut microbiota during aging, in particular gut microbiota characteristics of centenarians, can provide us possibility to achieving healthy aging or intervene pathological aging through gut microbiota-directed strategies.

AIM OF REVIEW

This review aims to summarize the characteristics of the gut microbiota associated with aging, explore potential biomarkers of aging and address microbiota-associated mechanisms of host aging focusing on intestinal barrier and immune status. By summarizing the existing effective dietary strategies in aging interventions, the probability of developing a diet targeting the gut microbiota in future is provided.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review is focused on three key notions: Firstly, gut microbiota has become a new target for regulating health status and lifespan, and its changes are closely related to age. Thus, we summarized aging-associated gut microbiota features at the levels of key genus/species and important metabolites through comparing the microbiota differences among centenarians, elderly people and younger people. Secondly, exploring microbiota biomarkers related to aging and discussing future possibility using dietary regime/components targeted to aging-related microbiota biomarkers promote human healthy lifespan. Thirdly, dietary intervention can effectively improve the imbalance of gut microbiota related to aging, such as probiotics, prebiotics, and postbiotics, but their effects vary among.

Christensenella minuta interacts with multiple gut bacteria

Introduction

Gut microbes form complex networks that significantly influence host health and disease treatment. Interventions with the probiotic bacteria on the gut microbiota have been demonstrated to improve host well-being. As a representative of next-generation probiotics, Christensenella minuta (C. minuta) plays a critical role in regulating energy balance and metabolic homeostasis in human bodies, showing potential in treating metabolic disorders and reducing inflammation. However, interactions of C. minuta with the members of the networked gut microbiota have rarely been explored.

Methods

In this study, we investigated the impact of C. minuta on fecal microbiota via metagenomic sequencing, focusing on retrieving bacterial strains and coculture assays of C. minuta with associated microbial partners.

Results

Our results showed that C. minuta intervention significantly reduced the diversity of fecal microorganisms, but specifically enhanced some groups of bacteria, such as Lactobacillaceae. C. minuta selectively enriched bacterial pathways that compensated for its metabolic defects on vitamin B1, B12, serine, and glutamate synthesis. Meanwhile, C. minuta cross-feeds Faecalibacterium prausnitzii and other bacteria via the production of arginine, branched-chain amino acids, fumaric acids and short-chain fatty acids (SCFAs), such as acetic. Both metagenomic data analysis and culture experiments revealed that C. minuta negatively correlated with Klebsiella pneumoniae and 14 other bacterial taxa, while positively correlated with F. prausnitzii. Our results advance our comprehension of C. minuta's in modulating the gut microbial network.

Conclusions

C. minuta disrupts the composition of the fecal microbiota. This disturbance is manifested through cross-feeding, nutritional competition, and supplementation of its own metabolic deficiencies, resulting in the specific enrichment or inhibition of the growth of certain bacteria. This study will shed light on the application of C. minuta as a probiotic for effective interventions on gut microbiomes and improvement of host health.

Gut commensal Christensenella minuta modulates host metabolism via acylated secondary bile acids

A strong correlation between gut microbes and host health has been observed in numerous gut metagenomic cohort studies. However, the underlying mechanisms governing host-microbe interactions in the gut remain largely unknown. Here we report that the gut commensal Christensenella minuta modulates host metabolism by generating a previously undescribed class of secondary bile acids with 3-O-acylation substitution that inhibit the intestinal farnesoid X receptor. Administration of C. minuta alleviated features of metabolic disease in high fat diet-induced obese mice associated with a significant increase in these acylated bile acids, which we refer to as 3-O-acyl-cholic acids. Specific knockout of intestinal farnesoid X receptor in mice counteracted the beneficial effects observed in their wild-type counterparts. Finally, we showed that 3-O-acyl-CAs were prevalent in healthy humans but significantly depleted in patients with type 2 diabetes. Our findings indicate a role for C. minuta and acylated bile acids in metabolic diseases.

Christensenella minuta, a new candidate next-generation probiotic: current evidence and future trajectories

Background

As the field of probiotic research continues to expand, new beneficial strains are being discovered. The Christensenellaceae family and its newly described member, Christensenella minuta, have been shown to offer great health benefits. We aimed to extensively review the existing literature on these microorganisms to highlight the advantages of their use as probiotics and address some of the most challenging aspects of their commercial production and potential solutions.

Methods

We applied a simple search algorithm using the key words "Christensenellaceae" and "Christensenella minuta" to find all articles reporting the biotherapeutic effects of these microorganisms. Only articles reporting evidence-based results were reviewed.

Results

The review showed that Christensenella minuta has demonstrated numerous beneficial properties and a wider range of uses than previously thought. Moreover, it has been shown to be oxygen-tolerant, which is an immense advantage in the manufacturing and production of Christensenella minuta-based biotherapeutics. The results suggest that Christensenellaceae and Christensenella munita specifically can play a crucial role in maintaining a healthy gut microbiome. Furthermore, Christensenellaceae have been associated with weight management. Preliminary studies suggest that this probiotic strain could have a positive impact on metabolic disorders like diabetes and obesity, as well as inflammatory bowel disease.

Conclusion

Christensenellaceae and Christensenella munita specifically offer immense health benefits and could be used in the management and therapy of a wide range of health conditions. In addition to the impressive biotherapeutic effect, Christensenella munita is oxygen-tolerant, which facilitates commercial production and storage.

Christensenella strain resources, genomic/metabolomic profiling, and association with host at species level

The gut commensal bacteria Christensenellaceae species are negatively associated with many metabolic diseases, and have been seen as promising next-generation probiotics. However, the cultured Christensenellaceae strain resources were limited, and their beneficial mechanisms for improving metabolic diseases have yet to be explored. In this study, we developed a method that enabled the enrichment and cultivation of Christensenellaceae strains from fecal samples. Using this method, a collection of Christensenellaceae Gut Microbial Biobank (ChrisGMB) was established, composed of 87 strains and genomes that represent 14 species of 8 genera. Seven species were first described and the cultured Christensenellaceae resources have been significantly expanded at species and strain levels. Christensenella strains exerted different abilities in utilization of various complex polysaccharides and other carbon sources, exhibited host-adaptation capabilities such as acid tolerance and bile tolerance, produced a wide range of volatile probiotic metabolites and secondary bile acids. Cohort analyses demonstrated that Christensenellaceae and Christensenella were prevalent in various cohorts and the abundances were significantly reduced in T2D and OB cohorts. At species level, Christensenellaceae showed different changes among healthy and disease cohorts. C. faecalis, F. tenuis, L. tenuis, and Guo. tenuis significantly reduced in all the metabolic disease cohorts. The relative abundances of C. minuta, C. hongkongensis and C. massiliensis showed no significant change in NAFLD and ACVD. and C. tenuis and C. acetigenes showed no significant change in ACVD, and Q. tenuis and Geh. tenuis showed no significant change in NAFLD, when compared with the HC cohort. So far as we know, this is the largest collection of cultured resource and first exploration of Christensenellaceae prevalences and abundances at species level.

Repressing effect of transformed ginsenoside Rg3-mix against LPS-induced inflammation in RAW264.7 macrophage cells

BACKGROUND

Rg3-ginsenoside, a protopanaxadiol saponin, is a well-known adaptogen used for the prevention of cancer and inflammation. However, despite its distinct biological activity, the concentration of Rg3 in the total ginseng extract is insufficient for therapeutic applications. This study aims to convert PPD-class of major ginsenosides into a mixture of minor ginsenoside, to analyze its immune-regulatory role in macrophage cells.

RESULTS

Using heat and organic acid treatment, three major ginsenosides, Rc, Rd, and Rb1, were converted into a mixture of minor ginsenosides, GRg3-mix [Rg3(S), Rg3(R), Rg5, and Rk1]. Purity and content analysis of the transformed compound were performed using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), compared with their standards. Preceding with the anti-inflammatory activity of GRg3-mix, lipopolysaccharide (LPS)-stimulated murine RAW264.7 macrophage cells were treated with various concentrations of GRg3-mix (6.25, 12.5, 25, and 50 μg/mL). The cell viability assay revealed that the level of cell proliferation was increased, while the nitric oxide (NO) assay showed that NO production decreased dose-dependently in activated RAW264.7 cells. The obtained results were compared to those of pure Rg3(S) ≥ 98% (6.25, 12.5, and 25 μg/mL). Preliminary analysis of the CCK-8 and NO assay demonstrated that GRg3-mix can be used as an anti-inflammatory mediator, but mRNA and protein expression levels were evaluated for further confirmation. The doses of GRg3-mix significantly suppressed the initially upregulated mRNA and protein expression of inflammation-related enzymes and cytokines, namely inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear transcription factor kappa B (NF-κB), tumor necrosis factor (TNF-α), and interleukins (IL-6 and IL1B), as measured by reverse transcription-polymerase chain reaction and western blotting.

CONCLUSIONS

Our pilot data confirmed that the mixture of minor ginsenosides, namely GRg3-mix, has high anti-inflammatory activity and has an easy production procedure.

Christensenella regulated by Huang-Qi-Ling-Hua-San is a key factor by which to improve type 2 diabetes

There is a lot of evidence that oral hypoglycemic drugs work by affecting gut microbes, but the key strains responsible for this effect are not well known. Huang-Qi-Ling-Hua-San (HQLHS), composed of Astragalus Membranaceus, Ganoderma lucidum, Inonotus obliquus, and Momordica charantia L., is a specially designed Chinese medicine formula to treat type 2 diabetes (T2D). In this study, a mouse model of T2D induced by high-fat diet and streptozotocin was used to explore the mechanism of HQLHS in improving hyperglycemia and hyperlipidemia through multiple rounds of animal experiments, such as HQLHS feeding, fecal microbiota transplantation (FMT), and live bacteria feeding, so as to explore the potential target intestinal flora in its hypoglycemic effect. Results show that such specific taxa as Bifidobacterium, Turicibacter, Alistipes, Romboutsia, and Christensenella were identified to be preferably enriched by HQLHS and then assumed to be the target microbes. Herein, FMT was used to test if the upregulated beneficial bacteria by HQLHS play a therapeutic role. The strain Christensenella minuta DSM 22607 and the strain Christensenella timonensis DSM 102800 were selected to test the beneficial effect of Christensenella taxa on T2D. Diabetic animals supplemented with these strains showed the improvement in blood glucose and lipid metabolism, the promotion of GLP-1 secretion, the increase in antioxidant capacity, the inhibition of hepatic gluconeogenesis, the suppression of intestinal glucose absorption, the enhancement of intestinal barrier, reduced LPS-induced inflammation, and the reduction of branched amino acids (BCAAs) content in the liver. Overall, these data demonstrate that Christensenella plays a beneficial role in T2D and is a target for the action of HQLHS therapy.

Over-feeding the gut microbiome: A scoping review on health implications and therapeutic perspectives

The human gut microbiome has gained increasing attention over the past two decades. Several findings have shown that this complex and dynamic microbial ecosystem can contribute to the maintenance of host health or, when subject to imbalances, to the pathogenesis of various enteric and non-enteric diseases. This scoping review summarizes the current knowledge on how the gut microbiota and microbially-derived compounds affect host metabolism, especially in the context of obesity and related disorders. Examples of microbiome-based targeted intervention strategies that aim to restore and maintain an eubiotic layout are then discussed. Adjuvant therapeutic interventions to alleviate obesity and associated comorbidities are traditionally based on diet modulation and the supplementation of prebiotics, probiotics and synbiotics. However, these approaches have shown only moderate ability to induce sustained changes in the gut microbial ecosystem, making the development of innovative and tailored microbiome-based intervention strategies of utmost importance in clinical practice. In this regard, the administration of next-generation probiotics and engineered microbiomes has shown promising results, together with more radical intervention strategies based on the replacement of the dysbiotic ecosystem by means of fecal microbiota transplantation from healthy donors or with the introduction of synthetic communities specifically designed to achieve the desired therapeutic outcome. Finally, we provide a perspective for future translational investigations through the implementation of bioinformatics approaches, including machine and deep learning, to predict health risks and therapeutic outcomes.

Exploration of Crucial Mediators for Carotid Atherosclerosis Pathogenesis Through Integration of Microbiome, Metabolome, and Transcriptome

Background

Carotid atherosclerosis (CAS) is an important cause of stroke. Although interactions between the gut microbiome and metabolome have been widely investigated with respect to the pathogenesis of cardiovascular diseases, information regarding CAS remains limited.

Materials and Methods

We utilized 16S ribosomal DNA sequencing and untargeted metabolomics to investigate the alterations in the gut microbiota and plasma metabolites of 32 CAS patients and 32 healthy controls. The compositions of the gut microbiota differed significantly between the two groups, and a total of 11 differentially enriched genera were identified. In the metabolomic analysis, 11 and 12 significantly changed metabolites were screened in positive (POS) and negative (NEG) modes, respectively. α-N-Phenylacetyl-L-glutamine was an upregulated metabolite in CAS patients detected in both POS and NEG modes and had the highest | log₂(fold change)| in POS mode. In addition, transcriptomic analysis was performed using the GSE43292 dataset.

Results

A total of 132 differentially expressed genes (DEGs) were screened. Among the upregulated DEGs in CAS patients, FABP4 exhibited the highest | log₂(fold change)|. Furthermore, FABP4 was positively associated with Acidaminococcus and had the highest Spearman’s correlation coefficient and the most significant p-value among the microbiota–DEG pairs.

Conclusion

In this study, we investigated the potential “microbiota–metabolite–gene” regulatory axis that may act on CAS, and our results may help to establish a theoretical basis for further specialized study of this disease.

Abietic acid ameliorates psoriasis-like inflammation and modulates gut microbiota in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Abietic acid (AA), an antibacterial terpenoid, was initially isolated from rosin which has been used as a traditional Chinese medicine to treat psoriasis. In our previous works, we found that water-processed rosin (WPR) can alleviate imiquimod (IMQ)-induced psoriasis-like inflammation in mice. However, the efficacy of AA, the main component of WPR, against psoriasis remains unclear.

MATERIALS AND METHODS

In this study, we confirmed the anti-psoriasis efficacy of AA (40 mg/kg daily for 7 days) in IMQ-induced psoriasis-like inflammation BALB/c mouse model by the psoriasis area severity index (PASI), flow cytometry, ELISA, histopathological and immunohistochemical analysis. Furthermore, we detected the relative abundance of gut microbe using high-throughput 16S rRNA gene sequencing to validate whether AA modulate gut microbe.

RESULT

Oral administration of AA ameliorates IMQ-induced psoriasis-like skin inflammation through reducing PASI scores, regulating the balance of Th17/Treg cells in the mouse spleen, and downregulating the level of serum cytokines such as TNF-α, IL-17A, TGF-1β, and IL-23. 16S rRNA gene sequencing revealed that the relative abundance of gut bacteria related to inflammation, such as, Anaerotruncus and Christensenella at genus level were decreased, while Kurthia, Citrobacter, and Klebsiella at genus level were increased in AA group mice. Additionally, the correlation analysis illustrated that the key microbiota had a close relationship with the psoriasis-like inflammation related indexes.

CONCLUSION

AA might exert the anti-psoriasis effect via inhibiting Th17-related immune responses, hinting that it might be a candidate for treating psoriasis. Meanwhile, the alteration of intestinal microbiota by AA treatment is another possible explanation for the amelioration of imiquimod-induced psoriasis-like inflammation.

Meta-omics characteristics of intestinal microbiota associated to HBeAg seroconversion induced by oral antiviral therapy

Tenofovir and entecavir are currently designated as the preferred oral antiviral drugs for chronic hepatitis B. However, only less than 40% of patients can achieve HBeAg seroconversion. We aim at investigating the role of intestinal microbiome in HBeAg seroconversion induced by oral antiviral therapy and describe multi-omics characteristics of HBeAg seroconversion associated intestinal flora. In this study, we prospectively collected fecal samples at baseline from the patients with HBeAg positive chronic hepatitis B who would have oral antiviral therapy. 16S rDNA sequencing and metabolomics were performed. We identified HBeAg seroconversion-related microbial signature and constructed prediction model for HBeAg seroconversion. Thirty-seven of these subjects achieved HBeAg seroconversion within 156 weeks after the initiation of oral antiviral therapy, while 41 subjects remained HBeAg positive even after over 156 weeks of therapy. A computational statistical and machine learning approach allowed us to identify a microbial signature for HBeAg seroconversion. Using random forest method, we further constructed a classifier based on the microbial signature, with area under curve being 0.749 for the test set. Patients who achieved HBeAg seroconversion tended to have lower abundance of certain fecal metabolites such as essential amino acids, and several dipeptides. By analyzing the fecal microbiota from the patients with and without HBeAg seroconversion, we showed intestinal microbiome play a critical role in HBeAg seroconversion induced by oral antiviral therapy. We also identified intestinal microbial signature that is associated with HBeAg seroconversion after oral antiviral therapy.

Commensal Obligate Anaerobic Bacteria and Health: Production, Storage, and Delivery Strategies

In the last years several human commensals have emerged from the gut microbiota studies as potential probiotics or therapeutic agents. Strains of human gut inhabitants such as Akkermansia, Bacteroides, or Faecalibacterium have shown several interesting bioactivities and are thus currently being considered as food supplements or as live biotherapeutics, as is already the case with other human commensals such as bifidobacteria. The large-scale use of these bacteria will pose many challenges and drawbacks mainly because they are quite sensitive to oxygen and/or very difficult to cultivate. This review highlights the properties of some of the most promising human commensals bacteria and summarizes the most up-to-date knowledge on their potential health effects. A comprehensive outlook on the potential strategies currently employed and/or available to produce, stabilize, and deliver these microorganisms is also presented.

The human gut bacteria Christensenellaceae are widespread, heritable, and associated with health

The Christensenellaceae, a recently described family in the phylum Firmicutes, is emerging as an important player in human health. The relative abundance of Christensenellaceae in the human gut is inversely related to host body mass index (BMI) in different populations and multiple studies, making its relationship with BMI the most robust and reproducible link between the microbial ecology of the human gut and metabolic disease reported to date. The family is also related to a healthy status in a number of other different disease contexts, including obesity and inflammatory bowel disease. In addition, Christensenellaceae is highly heritable across multiple populations, although specific human genes underlying its heritability have so far been elusive. Further research into the microbial ecology and metabolism of these bacteria should reveal mechanistic underpinnings of their host-health associations and enable their development as therapeutics.

High rejection rate of polysaccharides by microfiltration benefits Christensenella minuta and acetic acid production in an anaerobic membrane bioreactor for sludge fermentation

Substrates, the microbial community, and volatile fatty acids (VFAs) are interacting factors in anaerobic fermentation. In this paper, a microfiltration membrane was installed in a conventional reactor for sludge anaerobic fermentation, and changes in the VFA composition and the microbial community structure after the application were monitored. The membrane rejected much more polysaccharide than protein. VFA production, mainly acetic acid, was greatly enhanced by the membrane separation. The glycolytic species Christensenella minuta was significantly enriched. The explanation was inferred to be the higher retention rate of polysaccharide compared with proteins by the microfiltration. However, surprisingly, another polysaccharide using genus, Parabacteroides, did not benefit from the application of the membrane separation, suggesting more complicated mechanisms might be involved.

Biotechnology of health-promoting bacteria

Over the last decade, there has been an increasing scientific and public interest in bacteria that may positively contribute to human gut health and well-being. This interest is reflected by the ever-increasing number of developed functional food products containing health-promoting bacteria and reaching the market place as well as by the growing revenue and profits of notably bacterial supplements worldwide. Traditionally, the origin of probiotic-marketed bacteria was limited to a rather small number of bacterial species that mostly belong to lactic acid bacteria and bifidobacteria. Intensifying research efforts on the human gut microbiome offered novel insights into the role of human gut microbiota in health and disease, while also providing a deep and increasingly comprehensive understanding of the bacterial communities present in this complex ecosystem and their interactions with the gut-liver-brain axis. This resulted in rational and systematic approaches to select novel health-promoting bacteria or to engineer existing bacteria with enhanced probiotic properties. In parallel, the field of gut microbiomics developed into a fertile framework for the identification, isolation and characterization of a phylogenetically diverse array of health-promoting bacterial species, also called next-generation therapeutic bacteria. The present review will address these developments with specific attention for the selection and improvement of a selected number of health-promoting bacterial species and strains that are extensively studied or hold promise for future food or pharma product development.