Gut microbiota derived bile acid metabolites maintain the homeostasis of gut and systemic immunity

Effects of Grape Seed Proanthocyanidins on Growth Performance, Jejunal Antioxidant Capacity, Gut Microbial Diversity, and Metabolites in Kangle Chickens

This study examined the effects of dietary supplementation with grape seed proanthocyanidins (GSPs) on the growth performance, serum biochemistry, jejunal antioxidant capacity, and jejunal microbiota and metabolites in Chinese indigenous Kangle chicken. In this experiment, 120 female Kangle chickens aged 30 days old were randomly allocated into three treatment groups: a control group (CON) fed a standard diet and two experimental groups fed diets supplemented with 200 mg/kg (LGSP) or 400 mg/kg (HGSP) of GSPs. The experiment consisted of a 7-day adaptation period followed by a 30-day feeding trial. The results demonstrated that GSP supplementation did not significantly improve their average daily gain or feed efficiency. However, the HGSP group showed significant improvements in their liver and jejunal indices, a reduced jejunal crypt depth, and increased villus-height-to-crypt-depth ratios compared to these values in the CON group. Furthermore, the HGSP group also exhibited elevated concentrations of cholesterol in their serum. Additionally, the oxidative stress levels were probably reduced in the jejuna of the HGSP group, as evidenced by reduced malondialdehyde (MDA) contents. Although jejunal microbial diversity remained unchanged, the metabolomic analysis identified significant upregulation of jejunal metabolites, particularly those associated with free radical scavenging, protein nutrition, and bile acid metabolism, which would be beneficial for maintaining intestinal health. These findings indicate that supplementing their diet with 400 mg/kg of GSPs could improve the health of Kangle chickens, underscoring their potential as a functional feed additive in the production of indigenous Chinese chickens.

Interplay between the gut microbiota, its metabolites and carcinogens

The gut microbiota is a complex and dynamic community of microorganisms that reside in the gastrointestinal tract, playing a critical role in the host. It produces many metabolites, such as bile acids, which play an important role in the metabolism of the host. One area of particular interest is its involvement in the development and treatment of cancer. Carcinogens, which are substances known to promote cancer formation and development, are present in various sources in our daily lives, including cigarettes, barbecues, and moldy foods. The types, amounts, and metabolism of carcinogens have been closely linked to cancer risk, underscoring the importance of understanding their interplay with the gut microbiota. Numerous studies have demonstrated significant differences in the composition and function of the gut microbiota in individuals with cancer compared to healthy individuals. The gut microbiota and its metabolites have been shown to influence the metabolism of various carcinogens, thereby affecting cancer progression. While much attention has been paid to the relationship between the gut microbiota and cancer risk, the potential interplay between the gut microbiota and carcinogens has received less focus. This review aims to emphasize the importance of exploring the interplay between the gut microbiota with its metabolites and carcinogens in cancer development and therapy. By uncovering the mechanisms of the interplay, new approaches for cancer prevention and treatment can be developed.

Murine norovirus allosteric escape mutants mimic gut activation

Murine norovirus (MNV) undergoes large conformational changes in response to the environment. The T=3 icosahedral capsid is composed of 180 copies of ~58 kDa VP1 that has N-terminal (N), shell (S), and C-terminal protruding (P) domains. In phosphate-buffered saline, the P domains are loosely tethered to the shell and float ~15 Å above the surface. At conditions found in the gut (i.e., low pH with high metal ion and bile salt concentrations), the P domain rotates and drops onto the shell with intra P domain changes that enhance receptor interactions while blocking antibody binding. Two of our monoclonal antibodies (2D3 and 4F9) have broad strain recognition, and the only escape mutants, V339I and D348E, are located on the C'D' loop and ~20 Å from the epitope. Here, we determined the cryo-EM structures of V339I and D348E at neutral pH +/-metal ions and bile salts. These allosteric escape mutants have the activated conformation in the absence of gut triggers. Since this conformation is not recognized by antibodies, it explains how these mutants evade antibody recognition. Dynamic simulations of the P domain further suggest that movement of the C'D' loop may be the rate-limiting step in the conformational change and that V339I increases the motion of the A'B'/E'F' loops compared to the wild-type (WT), facilitating the transition to the activated state. These findings have important implications for norovirus vaccine design since they uncover a form of the viral capsid that should lend superior immune protection against subsequent challenge by wild-type virus.IMPORTANCEImmune protection from norovirus infection is notoriously transient in both humans and mice. Our results strongly suggest that this is likely because the "activated" form of the virus found in gut conditions is not recognized by antibodies created in the circulation. By reversibly presenting one structure in the gut and a completely different antigenic structure in circulation, the gut tissue can be infected in subsequent challenges, while extraintestinal organs are protected. We find here that allosteric escape mutants to the most broadly neutralizing antibodies thwart recognition by transitioning to the activated state without the need for gut triggers (i.e., bile, low pH, or metal ions). These findings are significant because it is now feasible to present the activated form of the virus to the immune system (for example, as a vaccine) to better protect the gut tissue for longer periods of time.

The functions of gut microbiota-mediated bile acid metabolism in intestinal immunity

BACKGROUND

Bile acids, derived from cholesterol in the liver, consist a steroidal core. Primary bile acids and secondary bile acids metabolized by the gut microbiota make up the bile acid pool, which modulate nuclear hormone receptors to regulate immunity. Disruptions in the crosstalk between bile acids and the gut flora are intimately associated with the development and course of gastrointestinal inflammation.

AIM OF REVIEW

This review provides an extensive summary of bile acid production, transport and metabolism. It also delves into the impact of bile acid metabolism on the body and explores the involvement of bile acid-microbiota interactions in various disease states. Furthermore, the potential of targeting bile acid signaling as a means to prevent and treat inflammatory bowel disease is proposed.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, we primarily address the functions of bile acid-microbiota crosstalk in diseases. Firstly, we summarize bile acid signalling and the factors influencing bile acid metabolism, with highlighting the immune function of microbially conjugated bile acids and the unique roles of different receptors. Subsequently, we emphasize the vital role of bile acids in maintaining a healthy gut microbiota and regulating the intestinal barrier function, energy metabolism and immunity. Finally, we explore differences of bile acid metabolism in different disease states, offering new perspectives on restoring the host's health and the gastrointestinal ecosystem by targeting the gut microbiota-bile acid-bile acid receptor axis.

Comparative analysis of different Phyllostachys species on gut microbiome and fecal metabolome in giant pandas (Ailuropoda melanoleuca)

The influences of different bamboo species on the microbiome and metabolome of giant pandas (Ailuropoda melanoleuca) remain understudied. The aim of this study was to investigate the effects of different Phyllostachys species on the gut microbial communities and fecal metabolite profiles in giant pandas. Metagenome and metabolome were performed on the feces of giant pandas fed with different Phyllostachys species (P. edulis, P. iridescens, P. glauca, and P. violascens). The results of metagenome showed that dietary with P. glauca could notably decrease the microbial Shannon index. The relative abundances of both Cellulosilyticum and Pseudomonas were enhanced after dietary with P. iridescens, suggesting P. iridescens could enhance the cellulose-degrading function in giant pandas. However, dietary with P. glauca or P. violascens could increase the relative abundances of certain pathogenic bacteria (Escherichia, Shigella, and Klebsiella). Metabolomics analysis further revealed that all experimental groups exhibited notably elevated levels of fecal flavonoids and fatty acids. In addition, the correlation analysis showed that certain nutrients of bamboo leaves (mainly crude protein and Cu) were significantly correlated with several differential gut bacteria and fecal metabolites. Based on the present results, P. iridescens might be a substitute for the routinely used Phyllostachys species (P. edulis) in the captive management of giant pandas. The results have revealed that bamboo species is an important factor affecting the gut microbiota and fecal metabolites in giant pandas. Our results could provide important information about bamboo species-induced alterations on the microbiome and metabolome in giant pandas.

The Role of Bile Acid in Immune-Mediated Skin Diseases

Immune-mediated skin disorders arise from dysfunctional immune responses, instigating inflammatory dermatoses and a reduced quality of life. The complex pathogenesis likely involves genetic risks, environmental triggers and aberrant immune activation. An emerging body of evidence suggests that bile acid disturbances may critically promote immune pathology in certain skin conditions. Bile acids synthesised from cholesterol regulate nutrient metabolism and immune cell function via nuclear receptors and G protein-coupled receptors (GPCRs). Altered bile acid profiles and receptor expression have been identified in psoriasis, atopic dermatitis (AD) and autoimmune blistering diseases. Disruptions in bile acid signalling affect the inflammatory and metabolic pathways linked to these disorders. Targeting components of the bile acid axis represents a promising therapeutic strategy. This review elucidates the intricate links between bile acid homeostasis and immune dysfunction in inflammatory skin diseases, synthesising evidence that targeting bile acid pathways may unlock innovative therapeutic avenues. This study compiles clinical and experimental data revealing disrupted bile acid signalling and composition in various immune-mediated dermatoses, highlighting the emerging significance of bile acids in cutaneous immune regulation.

LncRNA29RIK in macrophages promotes LPS-mediated sensitivity to obesity

Lipopolysaccharide (LPS, endotoxin) -mediated signaling of caspase-4 (human) and -11 (rodent) can induce the maturation of inflammatory cytokine IL-1β and cell pyroptosis, which is associated with the pathophysiology of many diseases such as obesity. However, the process by which LPS induces inflammation through caspase 4/11 is not fully understood. We found here that lncRNA29RIK plays a key role in LPS-mediated maturation of inflammatory cytokine IL-1β and pyroptosis of macrophages. Mechanistic ally, the binding of caspase 4/11 to LPS requires lncRNARIK to cause activation of the caspase 4/11 complex, which ultimately caused inflammation to promote sensitivity to high fat diet (HFD) -mediated obesity. Notably, lncRNA29RIK expression can be up-regulated by LPS. This lncRNA29 is highly conserved between humans and mice. Taken together, these results suggest that lncRNA29RIK determines the occurrence and progression of LPS-related diseases such as obesity.

Huang-qin decoction alleviates deoxycholic acid-induced colorectal cancer in mice by regulating gut microbiota

ETHNOPHARMACOLOGICAL RELEVANCE

Huangqin Decoction (HQD), a traditional Chinese medicine (TCM) formula documented in Shang Han Lun, has demonstrated safety and efficacy in the treatment of ulcerative colitis (UC). Recent studies also suggest that HQD exerts therapeutic effects on colorectal cancer (CRC). However, the underlying mechanisms remain unclear.

AIMS OF THE STUDY

This study aimed to investigate the therapeutic effects of HQD on CRC and explore its potential mechanisms of action.

METHODS

The active ingredients and potential targets of HQD were identified through network pharmacology-based analyses. The CRC-related targets were compared with those of HQD. Shared targets were subjected to Gene Ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and a protein-protein interaction (PPI) network was constructed. Additionally, APCmin/+ mice were treated with 0.2 % deoxycholic acid (DCA) and gavaged with low or high doses of HQD. Tumor morphology was assessed using hematoxylin and eosin (HE) staining. Immunohistochemical staining was performed to evaluate the expression of Ki-67, Caspase-3, and MUC2 in the intestine. Periodic acid-Schiff (PAS) and PAS-alcian blue (PAS-AB) staining were utilized to detect mucin distribution and the number of goblet cells in the intestines of the mice. The mRNA expression levels of interleukin 6 (IL-6), mitogen-activated protein kinase 8 (MAPK8), vascular endothelial growth factor A (VEGFA), epidermal growth factor receptor (EGFR), albumin (ALB), and Caspase 3 (CASP3) were quantified using quantitative reverse-transcription PCR (qRT-PCR). Immunofluorescence was employed to assess the degree of apoptosis. Additionally, 16S ribosomal RNA gene sequencing, sequence curation and annotation, and metagenomic sequencing were performed to analyze changes in the composition of the mouse intestinal microbiota and related functions and signaling pathways.

RESULTS

The active ingredients of HQD were identified. GO and KEGG pathway enrichment analyses indicated that the shared targets were primarily involved in tumor suppression. HQD effectively treated DCA-induced CRC in mice. Furthermore, positive PAS and PAS-AB staining was significantly increased in the intestines of mice treated with HQD. HQD enhanced the abundance of Lachnospiraceae, Firmicutes, Fusobacteria, and Clostridium, while reducing the abundance of Eggerthellales. Additionally, HQD modulated secondary bile acid metabolism, carbohydrate synthesis, and other energy metabolism pathways, which may underlie its therapeutic effects.

CONCLUSION

HQD effectively treated CRC in mice, and its mechanisms of action may be related to the regulation of the gut microbiota.

Gut microbiota derived indole-3-acetic acid ameliorates precancerous inflammatory intestinal milieu to inhibit tumorigenesis through IL-35

BACKGROUND

Gut microbiota can significantly alter the risk or progression of cancer by maintaining gut immune system homeostasis. However, the exact mechanism by which the gut microbiota and its metabolites influence colorectal tumorigenesis is unclear.

METHODS

The roles of tryptophan metabolite indole-3-acetic acid (IAA) in inflammation and tumor development were investigated in dextran sodium sulfate (DSS) and azoxymethane (AOM)-DSS mouse models with or without IAA supplementation and with or without Lactobacillus reuteri-produced IAA. Pregnane X receptor (PXR) knockout (KO) mice and aryl hydrocarbon receptor KO mice were used to explore the mechanism by which IAA regulates interleukin (IL)-35 expression. IL-35+ immune cells were stimulated in vitro and analyzed by flow cytometry. Additionally, metabolites were analyzed by liquid chromatography-mass spectrometry.

RESULTS

We found that IAA, a metabolite of tryptophan produced in the gut by L. reuteri, can inhibit the development of colitis by inducing IL-35 expression in immunosuppressant cells. HuREG3αIECtg mice had high levels of intestinal microbiota-derived IAA, and these mice were resistant to AOM-DSS-induced cancer. Patients with colorectal cancer also had low peripheral blood levels of IAA. Further studies revealed that IAA-producing L. reuteri alleviated colitis symptoms and inhibited colon tumors by inducing macrophages, T cells, and B cells to produce IL-35. Finally, PXR KO completely abolished the effects of IAA on immune cells.

CONCLUSION

We demonstrate that gut microbiota-derived IAA can improve the precancerous colon inflammatory environment through IL-35, thereby inhibiting tumorigenesis, suggesting that IAA may be a preventive factor for colitis-related cancers.

Microbiota-produced immune regulatory bile acid metabolites control central nervous system autoimmunity

The commensal gut microbiota has a role in the pathogenesis of extra-intestinal autoimmune diseases such as multiple sclerosis (MS) with unknown mechanisms. Deoxycholic acid (DCA) and lithocholic acid (LCA) are secondary bile acid metabolites (BAMs) produced from primary bile acids by gut microbiota that play key immune regulatory functions by promoting FOXP3+ regulatory T (Treg) cell differentiation at the expense of Th17 cells. Here, we show that bacteria releasing enzymes responsible for secondary BAMs production are under-represented in the gut of MS patients, resulting in significantly reduced intestinal concentration of DCA and immune dysregulation with increased percentage of Th17 cells. We validated our human findings in a preclinical model of MS by showing that DCA/LCA administration prevents experimental autoimmune encephalomyelitis (EAE) by dampening Th17 cell differentiation and the effector phenotype of myelin-reactive T cells. Our data highlight the key role of immune regulatory BAMs for the prevention of central nervous system (CNS) autoimmunity.

Suppressed intestinal secondary bile acids in moxifloxacin-induced hyperglycemia: studies in normal and diabetic GK rats

Objective

Moxifloxacin (MFLX) frequently induces dysglycemia when used in the treatment of infectious diseases, particularly in patients with diabetes. However, the mechanism through which MFLX affects host glucose metabolism remains unclear. This study aimed to investigate the possible mechanism underlying MFLX-induced hyperglycemia.

Methods

In this study, we investigated the short-term (3 days) and long-term (14 days) effects of MFLX on glucose metabolism in normal and type 2 diabetic GK rats. After oral administration of 40 mg/kg of MFLX, blood glucose, insulin, GLP-1, and fibroblast growth factor 15 (FGF15) levels in the blood of rats, as well as bile acids in both blood and feces, and gut microbiota, were examined. Liver and ileum tissues were promptly harvested for detecting the expression of hepatic 7α-hydroxylase (CYP7A1) and intestinal Takeda G-protein-coupled receptor 5 (TGR5) and farnesoid X receptor (FXR). In addition, we explored the effect of secondary bile acids (SBAs) on GLP-1 secretion in NCI-H716 cells, and observed the direct effect of MFLX on the expression of CYP7A1 in HepG2 cells and TGR5, FXR in NCI-H716 cells.

Results

It was demonstrated that MFLX induced hyperglycemia in diabetic rats, with a more pronounced reduction in serum insulin, GLP-1, and FGF15 levels than observed in normal rats. Gut microbiota associated with SBAs metabolism were significantly reduced, leading to decreased intestinal deoxycholic acid (DCA) and lithocholic acid (LCA). In vitro studies revealed that DCA and LCA (25 μM, 50 μM, and 100 μM) promoted GLP-1 secretion in a concentration-dependent manner in NCI-H716 cells. Meanwhile, we observed that the expression of intestinal TGR5 and FXR significantly downregulated, whereas CYP7A1 expression in liver was increased in GK rats after MFLX treatment. MFLX itself (0.1 μM, 1 μM, and 10 μM) did not directly altered TGR5 or FXR expressions in NCI-H716 cells, nor did it alter CYP7A1 expression in HepG2 cells, which indicated that the impact of MFLX on glucose metabolism was primarily induced by changes in bile acids metabolism resulting from alterations in the gut microbiota.

Conclusion

Our studies showed MFLX more likely to cause hyperglycemia when used in diabetic states and highlighted the critical role of gut microbiota-SBAs-TGR5/FXR pathway in MFLX-induced hyperglycemia.

Role of the microbiome in regulation of the immune system

Immune health and metabolic functions are intimately connected via diet and the microbiota. Immune cells are continuously exposed to a wide range of microbes and microbial-derived compounds, with important mucosal and systemic ramifications. Microbial fermentation of dietary components in vivo generates thousands of molecules, some of which are integral components of the molecular circuitry that regulates immune and metabolic functions. These in turn protect against aberrant inflammatory or hyper-reactive processes and promote effector immune responses that quickly eliminate pathogens, such as SARS-CoV-2. Potent tolerance mechanisms should ensure that these immune cells do not over-react to non-pathogenic factors (e.g. food proteins), while maintaining the ability to respond to infectious challenges in a robust, effective and well controlled manner. In this review we examine the factors and mechanisms that shape microbiota composition and interactions with the host immune system, their associations with immune mediated disorders and strategies for intervention.

Assessing the causal effect of genetically predicted metabolites and metabolic pathways on vitiligo: Evidence from Mendelian randomization and animal experiments

Vitiligo is a common chronic skin depigmentation disorder that seriously decreases the patients' overall quality of life. Human blood metabolites could contribute to unraveling the underlying biological mechanisms of vitiligo. We used GWAS summary statistics to assess the causal association between genetically predicted 1400 serum metabolites and vitiligo risk by Mendelian randomization (MR). Then, after constructing the mouse model of vitiligo, we did non-targeted metabolomics analysis on the mouse serum and validated MR's pathway enrichment results ulteriorly. In the initial phase, MR analysis revealed causative associations between 36 metabolites and vitiligo risk, including 8 metabolite ratios and 28 individual metabolites (19 known and 9 unknown metabolites). In the validation stage, 7 metabolites were successfully validated. Of the 28 individual metabolites, most are related to lipid metabolism. Genetically predicted higher 4-oxo-retinoic acid showed the strongest protective effect on vitiligo, while the most potent risk effect was the increase in quinate. The metabolites associated with vitiligo risk are mainly enriched in alpha-linolenic acid metabolism, linoleic acid metabolism, arginine biosynthesis and metabolism pathways, validated through the serum metabolomics of vitiligo mouse. By integrating genomics and metabolomics, this study provides new insights into the association between metabolites and vitiligo, highlighting the potential roles of specific metabolites in the pathogenesis of vitiligo. These metabolites associated with vitiligo could serve as new biomarkers, further research could help to reveal how these metabolites influence specific pathways in the development of vitiligo.

Bile acids and their receptors in hepatic immunity

Similarly to conventional steroids, bile acids function as signaling molecules, acting on a family of membrane and nuclear receptors. The best-characterized bile acid-regulated receptors are the farnesoid X receptor, activated by primary bile acids, and the G-protein-coupled bile acid receptor 1 (also known as Takeda G protein-coupled receptor 5), which is activated by secondary bile acids, such as lithocholic acid (LCA) and deoxycholic acid. Both the farnesoid X receptor and G-protein-coupled bile acid receptor 1 are expressed in cells of innate immunity, monocytes/macrophages, and natural killer cells. Their activation in these cells provides counter-regulatory signals that are inhibitory in nature and attenuate inflammation. In recent years, however, it has been increasingly appreciated that bile acids biotransformations by intestinal microbiota result in the formation of chemically different secondary bile acids that potently regulate adaptive immunity. The 3-oxoLCA and isoalloLCA, two LCA derivatives, bind receptors such as the retinoic acid receptor-related orphan receptor gamma t (RORγt) and the vitamin D receptor (VDR) that are expressed only by lymphoid cells, extending the regulatory role of bile acids to T cells, including T-helper 17 cells and type 3 innate lymphoid cells (ILC3). In this novel conceptual framework, bile acids have emerged as one of the main components of the postbiota, the waste array of chemical mediators generated by the intestinal microbiota. Deciphering the interaction of these mediators with the immune system in the intestine and liver is a novel and fascinating area of bile acid renaissance.

Alginate oligosaccharides relieve estrogen-deprived osteosarcopenia by affecting intestinal Th17 differentiation and systemic inflammation through the manipulation of bile acid metabolism

Alginate oligosaccharides (AOS) have gained attention for their capacity to regulate human health as prebiotics. Osteosarcopenia is a progressive disease of the musculoskeletal system and result in heavy burden of patients. Studies suggest that gut microbiota is involved in the pathogenesis of osteosarcopenia, whether AOS can improve the symptoms of osteosarcopenia by modulating gut microbiota remains to be elucidated. In this study, we proved that 200 mg/kg body weight AOS (MW = 4.9 kDa, G/M = 1.88) treatment significantly increased bone mass, boosted muscle function, and promoted gut barrier integrity in ovariectomized (OVX) mice. After AOS treatment, a marked reduction in the proportion of intestinal Th17 subsets and in peripheral levels of relevant inflammatory cytokines was observed compared to the OVX group. 16S rRNA sequencing indicated that AOS treatment could restore the imbalance of gut microbiota caused by estrogen deficiency. Additionally, the impact of AOS on bile acid changes was revealed according to metabolomics. In particular, the Th17 differentiation inhibitor, such as isoLCA, were significantly upregulated after AOS treatment. In conclusion, AOS can alleviate the symptoms of osteoporosis by modulating the relative abundance of gut microbiota and bile acid metabolism, thereby reducing the proportion of intestinal Th17 cells and peripheral Inflammation.

Fecal microbiota transplantation promotes functional recovery in mice with spinal cord injury by modulating the spinal cord microenvironment

BACKGROUND

spinal cord injury (SCI) disrupts the gut microbiota, worsening the injury's impact. Fecal microbiota transplantation (FMT) is increasingly recognized as a promising strategy to improve neural function post-SCI, yet its precise mechanisms are still far from clear. The present study aims to elucidate how FMT influences motor function recovery and its underlying mechanisms utilizing a SCI mouse model.

METHODS

Mice with SCI received FMT from healthy donors. We used 16 S rRNA amplicon sequencing to analyze the alterations of gut microbes. Pathological alterations in the spinal cord tissue, including neuronal survival, axonal regeneration, cell proliferation, and neuroinflammation, were assessed among experimental groups. Additionally, RNA sequencing (RNA-seq) was used to explore alterations in relevant signaling pathways.

RESULTS

Significant shifts in gut microbiota composition following SCI were observed through 16 S rRNA analysis. On day 7 post-SCI, the FMT group exhibited a significantly higher diversity of gut microbiota compared to the ABX group, with the composition in the FMT group more closely resembling that of healthy mice. FMT promoted neuronal survival and axonal regeneration, leading to notable improvements in motor function compared to control mice. Immunofluorescence staining showed increased neuronal survival, alleviated extracellular matrix (ECM) deposition, diminished glial scar formation, and reduced inflammation in FMT-treated mice. RNA-seq analysis indicated that FMT induced transcriptomic changes associated with material metabolism, ECM remodeling, and anti-inflammatory responses.

CONCLUSIONS

FMT restored gut microbiota balance in SCI mice, mitigated inflammation, and promoted ECM remodeling, establishing an optimal environment for neural recovery. These findings demonstrated that FMT may represent a valuable approach to enhance functional recovery following SCI.

Immunobiology of bile and cholangiocytes

The biliary tract is now recognized as an immune organ, and within the biliary tract, both bile and cholangiocytes play a key role in maintaining immune defense and homeostasis. First, immunoreactive proteins such as secretory IgA provide local antimicrobial effects. Second, bile acids (BAs) protect the biliary tree from immune-related injury through receptor signaling, mainly via the membrane-bound receptor TGR5 on cholangiocytes. Third, the biliary microbiota, similar to the intestinal microbiota, contributes to sustaining a stable physiobiological microenvironment. Fourth, cholangiocytes actively modulate the expression/release of adhesion molecules and cytokines/chemokines and are involved in antigen presentation; additionally, cholangiocyte senescence and apoptosis also influence immune responses. Conversely, aberrant bile composition, altered BA profiles, imbalances in the biliary microbiota, and cholangiocyte dysfunction are associated with immune-mediated cholangiopathies, including primary biliary cholangitis, primary sclerosing cholangitis, and biliary atresia. While current therapeutic agents that modulate BA homeostasis and receptor signaling have shown promise in preclinical and clinical studies, future research on biliary/intestinal microbiota and cholangiocyte function should focus on developing novel therapeutic strategies for treating cholangiopathies.

Antibiotic exposure is associated with minimal gut microbiome perturbations in healthy term infants

BACKGROUND

The evolving infant gut microbiome influences host immune development and later health outcomes. Early antibiotic exposure could impact microbiome development and contribute to poor outcomes. Here, we use a prospective longitudinal birth cohort of n = 323 healthy term African American children to determine the association between antibiotic exposure and the gut microbiome through shotgun metagenomics sequencing as well as bile acid profiles through liquid chromatography-mass spectrometry.

RESULTS

Stool samples were collected at ages 4, 12, and 24 months for antibiotic-exposed (n = 170) and unexposed (n = 153) participants. A short-term substudy (n = 39) collected stool samples at first exposure, and over 3 weeks following antibiotics initiation. Antibiotic exposure (predominantly amoxicillin) was associated with minimal microbiome differences, whereas all tested taxa were modified by breastfeeding. In the short-term substudy, we observed microbiome differences only in the first 2 weeks following antibiotics initiation, mainly a decrease in Bifidobacterium bifidum. The differences did not persist a month after antibiotic exposure. Four species were associated with infant age. Antibiotic exposure was not associated with an increase in antibiotic resistance gene abundance or with differences in microbiome-derived fecal bile acid composition.

CONCLUSIONS

Short-term and long-term gut microbiome perturbations by antibiotic exposure were detectable but substantially smaller than those associated with breastfeeding and infant age.

Inter-organ metabolic interaction networks in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a multisystem metabolic disorder, marked by abnormal lipid accumulation and intricate inter-organ interactions, which contribute to systemic metabolic imbalances. NAFLD may progress through several stages, including simple steatosis (NAFL), non-alcoholic steatohepatitis (NASH), cirrhosis, and potentially liver cancer. This disease is closely associated with metabolic disorders driven by overnutrition, with key pathological processes including lipid dysregulation, impaired lipid autophagy, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and local inflammation. While hepatic lipid metabolism in NAFLD is well-documented, further research into inter-organ communication mechanisms is crucial for a deeper understanding of NAFLD progression. This review delves into intrahepatic networks and tissue-specific signaling mediators involved in NAFLD pathogenesis, emphasizing their impact on distal organs.

Gut microbiota contributes to the intestinal and extraintestinal immune homeostasis by balancing Th17/Treg cells

Gut microbiota is generally considered to play an important role in host health due to its extensive immunomodulatory activities. Th17 and Treg cells are two important CD4+ T cell subsets involved in immune regulation, and their imbalance is closely tied to many immune diseases. Recently, abundant researches have highlighted the importance of gut microbiota in supporting intestinal and extraintestinal immunity through the balance of Th17 and Treg cells. Here, we presented a comprehensive review of these findings. This review first provided an overview of gut microbiota, along with Th17/Treg cell differentiation and cytokine production. Subsequently, the review summarized the regulatory effects of gut microbiota (in terms of species, components, and metabolites) on the Th17/Treg cell balance in the local intestines and extraintestinal organs, such as lung, liver, brain, kidney, and bone. Specifically, the Th17 and Treg cells that can be modulated by gut microbiota originate not only from the gut and extraintestinal organs, but also from peripheral blood and spleen. Then, the microbial therapeutics, including probiotics, prebiotics, postbiotics, and fecal microbiota transplantation (FMT), were also reviewed because of their therapeutic potentials in addressing intestinal and extraintestinal diseases via the Th17/Treg axis. Finally, the review discussed the clinical applications and future study prospects of microbial therapeutics by targeting the Th17/Treg cell balance. In conclusion, this review focused on elucidating the regulatory effects of gut microbiota in balancing Th17/Treg cells to maintain intestinal and extraintestinal immune homeostasis, contributing to the further development and promotion of microbial therapeutics.

Bile Acids in Inflammatory Bowel Disease: From Pathophysiology to Treatment

Inflammatory bowel disease (IBD) is a chronic condition that affects about 7 million people worldwide, and new therapies are needed. Understanding the complex roles that bile acids (BAs) play in IBD may lead to the development of novel IBD treatments independent of direct immunosuppression. This review discusses the latest discoveries in the roles BAs play in IBD pathogenesis and explores how these discoveries offer promising new therapeutic targets to treat IBD and improve patient outcomes. Several therapies discussed include specific BA receptor (BAR) agonists, dietary therapies, supplements, probiotics, and mesenchymal stem cell therapies that have all been shown to decrease IBD disease activity.

Gut Microbial Dysbiosis and Implications in Solid Organ Transplantation

The gut microbiome has been shown to play a significant role in solid organ transplantation, potentially influencing graft function and patient outcomes. Dysbiosis, characterized by reduced microbial diversity and an increase in pathogenic taxa, has been linked to higher incidences of allograft rejection, graft dysfunction, and post-transplant mortality. Several studies suggest that the gut microbiome might be able to serve as both a biomarker and a therapeutic target, potentially guiding personalized immunosuppressive therapies and other interventions to improve outcomes after solid organ transplantation. As summarized in this review, clinical studies have shown that specific microbial shifts correlate with adverse outcomes, including acute rejection and chronic allograft dysfunction. As research surrounding the relationship between the gut microbiome and solid organ transplant progresses, the integration of microbial analysis into clinical practice has the potential to revolutionize post-transplant care, offering new avenues to improve graft survival and patient quality of life. This review aims to provide a comprehensive overview of the relationship between gut microbial dysbiosis and transplantation outcomes, emphasizing the impact on kidney, liver, lung, and heart transplant recipients.

Medium chain triglycerides alleviate non-alcoholic fatty liver disease through bile acid-mediated FXR signaling pathway: A comparative study with common vegetable edible oils

With the global epidemic trend of obesity, non-alcoholic fatty liver disease (NAFLD) has become a significant cause of chronic liver disease, seriously affecting human health. Medium-chain triglycerides (MCT) with a fatty acid chain length varying between 6 and 10 carbon atoms (most sources from coconut and palm kernel oils), which exhibited activities to improve lipid metabolism, prevent cardiovascular diseases, and enhance immunity. However, the efficacy differences and potential mechanisms between MCT and traditional long-chain vegetable oils (palm oil, PA; high oleic peanut oil, OA) in obesity-induced NAFLD were still unclear. The present study treated obesity-induced NAFLD mice with different dietary lipids for 16 weeks. The results showed that MCT supplements significantly improved abnormal elevation of weight gain and blood lipids and reduced hepatic lipid accumulation to a greater extent than PA and OA. Furthermore, bile acid profiling results indicated that MCT significantly changed the composition of bile acids in the liver, reduced the concentrations of cholic acid (CA), deoxycholic acid (DCA), β-muricholic acid (β-MCA), and ursodeoxycholic acid (UDCA) and increased the concentrations of chenodeoxycholic Acid (CDCA), taurochenodeoxycholic acid （TCDCA), hyodeoxycholic acid (HDCA), and taurohyodeoxycholic acid (THDCA). Mechanistically, MCT supplement upregulated FXR signal and inhibited the expression of key genes for triglyceride synthesis in the liver, thereby reducing hepatic lipid accumulation. In summary, MCT exerted a superior effect on PA and OA in improving obesity-induced NAFLD. These results provided new evidence for the application of MCT in treating NAFLD.

Metabolomics study of dietary Pleurotus eryngii β-type glycosidic polysaccharide on colitis induced by dextran sodium sulfate in mice - Exploration for the potential metabolic indicators in urine and serum

Pleurotus eryngii, an edible mushroom recognized for its potent polysaccharides, demonstrates significant regulatory effects on metabolic processes. β-glucan (WPEP) derived from P. eryngii has been noted for its therapeutic potential, exhibiting notable benefits in alleviating colonic inflammation and restructuring gut microbiota in mice treated with dextran sodium sulfate (DSS). This study focuses on utilizing DSS-induced colitis mice to explore the efficacy and underlying mechanisms of WPEP in ameliorating colitis, employing a metabolomics approach analyzing urine and serum. The findings reveal that WPEP administration effectively regulates metabolic imbalances in DSS mice, impacting purine metabolism, pentose and glucuronic acid interconversion, amino acid metabolism, primary bile acid biosynthesis, citric acid cycle, and lipid metabolism. Furthermore, WPEP demonstrates a capacity to modulate colitis by regulating diverse metabolic pathways, consequently influencing intestinal barrier integrity, motility, inflammation, oxidative stress, and immunity. These insights suggest that WPEP is a promising food component for managing inflammatory bowel diseases.

The Gut Microbiota and Its Metabolites and Their Association with the Risk of Autoimmune Thyroid Disease: A Mendelian Randomization Study

Objectives: Observational research shows associations of the gut microbiota and its metabolites with autoimmune thyroid disease (AITD), but the causality is undetermined. Methods: Two-sample Mendelian randomization (MR) was employed to analyze the association of the gut microbiota and its metabolites with AITD. A total of 119 gut microbiotas and nine fecal/circulating metabolites were the exposures. AITD, Graves' disease (GD), and Hashimoto's thyroiditis (HT) were the outcomes. Inverse-variance weighting (IVW) was primarily used to assess causality; Cochran's Q was used to assess heterogeneity. Sensitivity analyses (weighted median, MRPRESSO regression, MRPRESSO intercept, MRPRESSO global, Steiger filtering, leave-one-out) were conducted to assess causal estimate robustness. Multivariable MR (MVMR) was used to estimate the effects of body mass index (BMI) and alcohol consumption frequency on causality. Results: The outcomes were potentially causally associated with 22 gut microbiotas and three metabolites. After multiple-test correction, 3-indoleglyoxylic acid retained significant causality with AITD (IVW: odds ratio [OR] = 1.09, 95% confidence interval [CI] = 1.05-1.14, p = 2.43 × 10-5, FDR = 0.009). The sensitivity analyses were confirmatory (weighted median: OR = 1.06, 95% CI = 1.01-1.12, p = 0.025; MRPRESSO: OR = 1.09, 95% CI = 1.15-1.14, p = 0.001). MVMR revealed no confounding effects on this association (BMI: OR = 1.21, 95% CI =1.08-1.35, p = 0.001; drinks/week: OR = 1.22, 95% CI = 1.04-1.43, p = 0.014). Conclusions: MR revealed no significant causal effects of the gut microbiota on the outcomes. However, MR revealed the causal effects of 3-indoleglyoxylic acid on the risk of AITD.

Narrative Review: Advancing Dysbiosis Treatment in Onco-Hematology with Microbiome-Based Therapeutic Approach

This review explores the complex relationship between gut dysbiosis and hematological malignancies, focusing on graft-versus-host disease (GvHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. We discuss how alterations in microbial diversity and composition can influence disease development, progression, and treatment outcomes in blood cancers. The mechanisms by which the gut microbiota impacts these conditions are examined, including modulation of immune responses, production of metabolites, and effects on intestinal barrier function. Recent advances in microbiome-based therapies for treating and preventing GvHD are highlighted, with emphasis on full ecosystem standardized donor-derived products. Overall, this review underscores the growing importance of microbiome research in hematology-oncology and its potential to complement existing treatments and improve outcomes for thousands of patients worldwide.

Microbiota-gut-brain axis: Natural antidepressants molecular mechanism

BACKGROUND

Major depressive disorder (MDD) is a severe mental health condition characterized by persistent depression, impaired cognition, and reduced activity. Increasing evidence suggests that gut microbiota (GM) imbalance is closely linked to the emergence and advancement of MDD, highlighting the potential significance of regulating the "Microbiota-Gut-Brain" (MGB) axis to impact the development of MDD. Natural products (NPs), characterized by broad biological activities, low toxicity, and multi-target characteristics, offer unique advantages in antidepressant treatment by regulating MGB axis.

PURPOSE

This review was aimed to explore the intricate relationship between the GM and the brain, as well as host responses, and investigated the mechanisms underlying the MGB axis in MDD development. It also explored the pharmacological mechanisms by which NPs modulate MGB axis to exert antidepressant effects and addressed current research limitations. Additionally, it proposed new strategies for future preclinical and clinical applications in the MDD domain.

METHODS

To study the effects and mechanism by which NPs exert antidepressant effects through mediating the MGB axis, data were collected from Web of Science, PubMed, ScienceDirect from initial establishment to March 2024. NPs were classified and summarized by their mechanisms of action.

RESULTS

NPs, such as flavonoids,alkaloids,polysaccharides,saponins, terpenoids, can treat MDD by regulating the MGB axis. Its mechanism includes balancing GM, regulating metabolites and neurotransmitters such as SCAFs, 5-HT, BDNF, inhibiting neuroinflammation, improving neural plasticity, and increasing neurogenesis.

CONCLUSIONS

NPs display good antidepressant effects, and have potential value for clinical application in the prevention and treatment of MDD by regulating the MGB axis. However, in-depth study of the mechanisms by which antidepressant medications affect MGB axis will also require considerable effort in clinical and preclinical research, which is essential for the development of effective antidepressant treatments.

The expression of intestinal Cyp2c55 is regulated by the microbiota and inflammation

Although the mutualistic relationship between the intestinal microbiota and the human host is crucial for maintaining health, the underlying mechanisms of this relationship remain unclear. In the present study, aiming to elucidate the regulatory mechanisms governing the Cyp2c55 expression, which is predominantly observed in colonic tissues, germ-free, antibiotic-administered and colitic mice, as well as mouse colonoids, were used as experimental models. RNA sequencing showed comparable decreases in the colonic Cyp2c55 expression in germ-free and antibiotic-administered mice, when compared with that in specific pathogen-free mice. Furthermore, administration of dextran sulfate sodium decreased the Cyp2c55 expression in colitic mice. For these mice, a Pearson correlation analysis also showed a positive correlation between the Cyp2c55 expression and unconjugated bile acids (BAs), including chenodeoxycholic, muricholic, deoxycholic, lithocholic, and ursodeoxycholic acids, as well as taurine (T)-conjugated secondary BAs, including deoxycholic acid. Moreover, bacterial genera, such as Muribaculaceae and unclassified Lachnospiraceae, also exhibited a positive correlation with these BAs. While administration of an agonist of the pregnane X receptor (PXR) increased the Cyp2c55 expression in mouse colonoids, inflammatory cytokines decreased it. In conclusion, Cyp2c55 was highly expressed in the colonic epithelial cells of mice in a microbiota-dependent manner. The underlying mechanism seemed to involve a BA-mediated PXR activation. In addition, the colonic expression of Cyp2c55 was regulated by the inflammatory response. Although the physiological function of Cyp2c55 remains largely unidentified, our findings suggested that Cyp2c55 may play a role in the mutualistic interaction between the intestinal microbiota and the intestinal homeostasis.

Regulation of gut microbiota on immune cell ferroptosis: A novel insight for immunotherapy against tumor

Gut microbiota contributes to the homeostasis of immune system and is related to various diseases such as tumorigenesis. Ferroptosis, a new type of cell death, is also involved in the disease pathogenesis. Recent studies have found the correlations of gut microbiota mediated ferroptosis and immune cell death. Gut microbiota derived immunosuppressive metabolites, which can promote differentiation and function of immune cells, tend to inhibit ferroptosis through their receptors, whereas inflammatory metabolites from gut microbiota also affect the differentiation and function of immune cells and their ferroptosis. Thus, it is possible for gut microbiota to regulate immune cell ferroptosis. Indeed, gut microbiota metabolite receptor aryl hydrocarbon receptor (AhR) can affect ferroptosis of intestinal intraepithelial lymphocytes, leading to disease pathogenesis. Since immune cell ferroptosis in tumor microenvironment (TME) affects the occurrence and development of tumor, the modulation of gut microbiota in these cell ferroptosis might influence on the tumorigenesis, and also immunotherapy against tumors. Here we will summarize the recent advance of ferroptosis mediated by gut microbiota metabolites, which potentially acts as regulator(s) on immune cells in TME for therapy against tumor.

Effect of Gegen Qinlian Decoction on the regulation of gut microbiota and metabolites in type II diabetic rats

Gegen Qinlian Decoction (GGQLT) is a traditional Chinese herbal medicine that has been reported to have a significant therapeutic effect in the management of type II diabetes mellitus (T2DM). In this study, we constructed a T2DM rat model by feeding a high-fat diet and injecting streptozotocin (STZ) and tested the effects of feeding GGQLT and fecal transplantation on the physiological indices, microbiota, and metabolism of rats. The results showed that the administration of GGQLT can significantly improve the growth performance of rats and has a remarkable antihyperlipidemic effect. In addition, GGQLT altered the composition of gut microbiota by increasing beneficial bacteria such as Coprococcus, Bifidobacterium, Blautia, and Akkermansia. In addition, GGQLT elevated levels of specific bile acids by metabolomic analysis, potentially contributing to improvements in lipid metabolism. These findings suggest that GGQLT may have beneficial effects on T2DM by influencing lipid metabolism and gut microbiota. However, further studies are needed to elucidate its mechanisms and assess clinical applications.

Gut Microbiota Disorder Contributes to the Production of IL-17A That Exerts Chemotaxis via Binding to IL-17RA in Endometriosis

Introduction

Endometriosis (EM) is a chronic estrogen-dependent condition characterized by the growth of endometrial-like tissue outside the uterus, posing a significant burden on reproductive-aged women. Previous research has shown a correlation between gut microbiota dysbiosis and interleukin-17A (IL-17A) in EM patients. IL-17A, a promising immunomodulatory molecule, exerts dual roles in human physiology, driving inflammatory diseases. However, the functions and origins of IL-17A in EM remain poorly characterized.

Methods

Single-cell data analysis was employed to characterize IL-17A activity in EM lesions. Fecal microbiota transplantation was conducted to explore the impact of gut microbiota on EM. Gut microbiota and bile acid metabolism were assessed via 16S rRNA sequencing and targeted metabolomics. Th17 cell proportions were measured using flow cytometry.

Results

High expression of IL-17 receptor A (IL-17RA) was observed in myeloid cell subpopulations within EM lesions and may be involved in the migration and recruitment of inflammatory cells in lesions. Elevated IL-17A levels were further validated in peritoneal and follicular fluids of EM patients. Dysregulated bile acid levels, particularly elevated chenodeoxycholic acid (CDCA) and ursodeoxycholic acid (UDCA), were found in the gut and peritoneal fluid of EM mouse models. Additional CDCA administration reduced EM lesions and modulated Th17 cell proportions, while UDCA showed no significant effects.

Discussion

Our findings shed light on the origins and functions of IL-17A in EM, implicating its involvement in lesion migration and recruitment. Dysregulated bile acid metabolism may contribute to EM pathogenesis, with CDCA exhibiting therapeutic potential.

Bile acid metabolism in health and ageing-related diseases

Bile acids (BAs) have surpassed their traditional roles as lipid solubilizers and regulators of BA homeostasis to emerge as important signalling molecules. Recent research has revealed a connection between microbial dysbiosis and metabolism disruption of BAs, which in turn impacts ageing-related diseases. The human BAs pool is primarily composed of primary BAs and their conjugates, with a smaller proportion consisting of secondary BAs. These different BAs exert complex effects on health and ageing-related diseases through several key nuclear receptors, such as farnesoid X receptor and Takeda G protein-coupled receptor 5. However, the underlying molecular mechanisms of these effects are still debated. Therefore, the modulation of signalling pathways by regulating synthesis and composition of BAs represents an interesting and novel direction for potential therapies of ageing-related diseases. This review provides an overview of synthesis and transportion of BAs in the healthy body, emphasizing its dependence on microbial community metabolic capacity. Additionally, the review also explores how ageing and ageing-related diseases affect metabolism and composition of BAs. Understanding BA metabolism network and the impact of their nuclear receptors, such as farnesoid X receptor and G protein-coupled receptor 5 agonists, paves the way for developing therapeutic agents for targeting BA metabolism in various ageing-related diseases, such as metabolic disorder, hepatic injury, cardiovascular disease, renal damage and neurodegenerative disease.

Gut microbiota-dependent modulation of pre-metastatic niches by Jianpi Yangzheng decoction in the prevention of lung metastasis of gastric cancer

AIM OF THE STUDY

To evaluate the in vitro and in vivo anti-metastasis efficacy of Jianpi Yangzheng (JPYZ) decoction against gastric cancer (GC) and its potential mechanisms.

MATERIALS AND METHODS

The distant metastasis of GC cells administered via tail vein injection was assessed using the pre-metastatic niche (PMN) model. 16S rRNA sequencing and GC-MS/MS were applied to determine the component of the gut microbiota and content of short-chain fatty acids (SCFAs) in feces of mice, respectively. The proportion of myeloid-derived suppressor cells (MDSCs) in the lung was evaluated by flow cytometry and immunofluorescence. Serum or tissue levels of inflammation factors including IL-6, IL-10 and TGF-β were determined by ELISA or Western blot respectively.

RESULTS

Injecting GC cells into the tail vein of mice led to the development of lung metastases and also resulted in alterations in the composition of gut microbiota and the levels of SCFAs produced. Nevertheless, JPYZ treatment robustly impeded the effect of GC cells administration. Mechanically, JPYZ treatment not only prevented the alteration in gut microbiota structure, but also restored the SCFAs content induced by GC cells administration. Specifically, JPYZ treatment recovered the relative abundance of genera Moryella, Helicobacter, Lachnoclostridium, Streptococcus, Tuzzerella, GCA-900066575, uncultured_Lachnospiraceae, Rikenellaceae_RC9_gut_group and uncultured_bacterium_Muribaculaceae to near the normal control levels. In addition, JPYZ abrogated MDSCs accumulation in the lung tissue and blocked inflammation factors overproduction in the serum and lung tissues, which subsequently impede the formation of the immunosuppressive microenvironment. Correlation analysis revealed that the prevalence of Rikenellaceae in the model group exhibited a positive correlation with MDSCs proportion and inflammation factor levels. Conversely, the scarcity of Muribaculaceae in the model group showed a negative correlation with these parameters. This suggests that JPYZ might exert an influence on the gut microbiota and their metabolites, such as SCFAs, potentially regulating the formation of the PMN and consequently impacting the outcome of GC metastasis.

CONCLUSION

These findings suggest that GC cells facilitate metastasis by altering the gut microbiota composition, affecting the production of SCFAs, and recruiting MDSCs to create a pro-inflammatory pre-metastatic niche. JPYZ decoction counteracts this process by reshaping the gut microbiota structure, enhancing SCFA production, and inhibiting the formation of the pre-metastatic microenvironment, thereby exerting an anti-metastatic effect.

Assessment of the Risk of Malnutrition or Frailty Among Patients Undergoing Liver Transplantation: A Hospital-Based Prospective Study

Objective

We aimed to explore the status of nutritional and frailty in patients undergoing liver transplantation and the associated influencing factors.

Methods

We conducted a follow-up analysis of 44 patients who underwent liver transplantation between 2021 and 2022. We followed up and recorded the nutritional status and risk of weakness at different time-points (days 1, 2, 3, 6, 9, and 12) postoperatively. Patient information regarding demographics, physical examination, medical history, and perioperative blood tests were collected. Binary logistic regression was applied to identify risk factors for weakness after liver transplantation.

Results

The cohort comprised 44 liver transplant recipients, with a mean age of 47.66 years (standard deviation=9.49 years). Initial analysis revealed that, compared to the group without nutritional risks, the group with nutritional risks displayed elevated age and preoperative blood ammonia levels one week post-surgery. Moreover, this group had reduced levels of albumin and total bile acid preoperatively. Patients with preoperative nutritional risks were also prone to similar risks 2 weeks postoperatively. Further, a correlation was observed between preoperative pulmonary infections and increased frailty risk 6 days postoperatively. At both 9 and 12 days postoperatively, patients with frailty risk exhibited higher preoperative white blood cell counts and ammonia levels than those without. Multivariable analysis, controlling for confounding factors, indicated a significant association between preoperative nutritional status and nutritional risk 2 weeks postoperatively, as well as a link between preoperative white blood cell count and frailty risk at 12 days postoperatively.

Conclusion

There was a significant correlation between preoperative nutritional status and nutritional risk 2 weeks after liver transplantation, and preoperative white blood cell count was an independent risk factor for weakness 12 days postoperatively. Preoperative nutritional management for patients could potentially mitigate the likelihood of adverse clinical outcomes.

Heat stress-induced dysbiosis of the gut microbiota impairs spermatogenesis by regulating secondary bile acid metabolism in the gut

Heat stress (HS) poses a substantial challenge to livestock. Studies have demonstrated that HS reduces fertility and leads to gut microbiota dysbiosis in bulls. However, the impact of the gut microbiota on fertility in bulls during HS is still unclear. Our research revealed that HS exposure decreased semen quality in bulls, and fecal microbiota transplantation (FMT) from heat-stressed bulls to recipient mice resulted in a significant decrease in number of testicular germ cells and epididymal sperm. Untargeted metabolomics methodology and 16S rDNA sequencing conjoint analysis revealed that Akkermansia muciniphila (A. muciniphila) seemed to be a key bacterial regulator of spermatogenesis after HS exposure. Moreover, the research indicated that A. muciniphila regulated secondary bile acid metabolism by promoting the colonization of bile salt hydrolase (BSH)-metabolizing bacteria, leading to increase of retinol absorption in the host gut and subsequently elevation of testicular retinoic acid level, thereby improving spermatogenesis. This study sheds light on the relationship between HS-induced microbiota dysbiosis and spermatogenesis, offering a potential therapeutic approach for addressing bull spermatogenic dysfunction triggered by HS exposure.

Influence of Gut Microbiota-Mediated Immune Regulation on Response to Chemotherapy

The involvement of the gut microbiota in anti-cancer treatment has gained increasing attention. Alterations to the structure and function of the gut bacteria are important factors in the development of cancer as well as the efficacy of chemotherapy. Recent studies have confirmed that the gut microbiota and related metabolites influence the pharmacological activity of chemotherapeutic agents through interactions with the immune system. This review aims to summarize the current knowledge of how malignant tumor and chemotherapy affect the gut microbiota, how the gut microbiota regulates host immune response, and how interactions between the gut microbiota and host immune response influence the efficacy of chemotherapy. Recent advances in strategies for increasing the efficiency of chemotherapy based on the gut microbiota are also described. Deciphering the complex homeostasis maintained by the gut microbiota and host immunity provides a solid scientific basis for bacterial intervention in chemotherapy.

The impact of exercise on the gut microbiota in middle-aged amateur serious runners: a comparative study

Introduction

Exercise, health, and the gut microbiota (GM) are strongly correlated. Research indicates that professional athletes, especially ultra-marathon runners, have unique GM characteristics. However, more research has focused on elite athletes, with little attention given to amateur sports enthusiasts, especially those in the middle-aged population. Therefore, this study focuses on the impact of long-term running on the composition and potential functions of the GM in middle-aged individuals.

Methods

We compared the GM of 25 middle-aged serious runnerswith 22 sedentary healthy controls who had minimal exercise habitsusing 16S rRNA gene sequencing. Additionally, we assessed dietary habits using a food frequency questionnaire.

Results and Discussion

Statistical analysis indicates that there is no significant difference in dietary patterns between the control group and serious runners. Diversity analysis results indicate that there is no significant difference in α diversity between the two groups of GM, but there is a significant difference in β diversity. Analysis of the composition of GM reveals that Ruminococcus and Coprococcus are significantly enriched in serious runners, whereas Bacteroides, Lachnoclostridium, and Lachnospira are enriched in the control group. Differential analysis of functional pathway prediction results reveals significant differences in the functional metabolism levels of GM between serious runners and the control group. Further correlation analysis results indicate that this difference may be closely related to variations in GM. In conclusion, our results suggest that long-term exercise can lead to changes in the composition of the GM. These changes have the potential to impact the overall health of the individual by influencing metabolic regulation.

Muscularis macrophages controlled by NLRP3 maintain the homeostasis of excitatory neurons

Peristaltic movements in gut are essential to propel ingested materials through the gastrointestinal tract. Intestinal resident macrophages play an important role in this physiological function through protecting enteric neurons. However, it is incompletely clear how individuals maintain the homeostasis of gut motility. Here we found that NLRP3 is a critical factor in controlling loss of muscularis resident macrophages (MMs), and demonstrate that MMs are involved in the homeostasis of excitatory neurons such as choline acetyltransferase (ChAT)+ and vesicular glutamate transporter 2 (VGLUT2)+ but not inhibitory neuronal nitric oxide synthase (nNOS)+ neurons. NLRP3 knockout (KO) mice had enhanced gut motility and increased neurons, especially excitatory ChAT+ and VGLUT2+ neurons. Single cell analyses showed that there had increased resident macrophages, especially MMs in NLRP3 KO mice. The MM proportion in the resident macrophages was markedly higher than those in wild-type (WT) or caspase 1/11 KO mice. Deletion of the MMs and transplantation of the NLRP3 KO bone marrow cells showed that survival of the gut excitatory ChAT+ and VGLUT2+ neurons was dependent on the MMs. Gut microbiota metabolites β-hydroxybutyrate (BHB) could promote gut motility through protecting MMs from pyroptosis. Thus, our data suggest that MMs regulated by NLRP3 maintain the homeostasis of excitatory neurons.

Long-Term Triclocarban Exposure Induced Enterotoxicity by Triggering Intestinal AhR-Mediated Inflammation and Disrupting Microbial Community in Mice

Exposure to triclocarban (TCC), a commonly used antibacterial agent, has been shown to induce significant intestine injuries and colonic inflammation in mice. However, the detailed mechanisms by which TCC exposure triggered enterotoxicity remain largely unclear. Herein, intestinal toxicity effects of long-term and chronic TCC exposure were investigated using a combination of histopathological assessments, metagenomics, targeted metabolomics, and biological assays. Mechanically, TCC exposure caused induction of intestinal aryl hydrocarbon receptor (AhR) and its transcriptional target cytochrome P4501A1 (Cyp1a1) leading to dysfunction of the gut barrier and disruption of the gut microbial community. A large number of lipopolysaccharides (LPS) are released from the gut lumen into blood circulation owing to the markedly increased permeability and gut leakage. Consequently, toll-like receptor-4 (TLR4) and NF-κB signaling pathways were activated by high levels of LPS. Simultaneously, classic macrophage phenotypes were switched by TCC, shown with marked upregulation of macrophage M1 and downregulation of macrophage M2 that was accompanied by striking upregulation of proinflammatory factors such as Il-1β, Il-6, Il-17, and Tnf-α in the intestinal lamina propria. These findings provide new evidence for the TCC-induced enterotoxicity.

When inflammatory stressors dramatically change, disease phenotypes may transform between autoimmune hematopoietic failure and myeloid neoplasms

Aplastic anemia (AA) and hypoplastic myelodysplastic syndrome are paradigms of autoimmune hematopoietic failure (AHF). Myelodysplastic syndrome and acute myeloid leukemia are unequivocal myeloid neoplasms (MNs). Currently, AA is also known to be a clonal hematological disease. Genetic aberrations typically observed in MNs are detected in approximately one-third of AA patients. In AA patients harboring MN-related genetic aberrations, a poor response to immunosuppressive therapy (IST) and an increased risk of transformation to MNs occurring either naturally or after IST are predicted. Approximately 10%-15% of patients with severe AA transform the disease phenotype to MNs following IST, and in some patients, leukemic transformation emerges during or shortly after IST. Phenotypic transformations between AHF and MNs can occur reciprocally. A fraction of advanced MN patients experience an aplastic crisis during which leukemic blasts are repressed. The switch that shapes the disease phenotype is a change in the strength of extramedullary inflammation. Both AHF and MNs have an immune-active bone marrow (BM) environment (BME). In AHF patients, an inflamed BME can be evoked by infiltrated immune cells targeting neoplastic molecules, which contributes to the BM-specific autoimmune impairment. Autoimmune responses in AHF may represent an antileukemic mechanism, and inflammatory stressors strengthen antileukemic immunity, at least in a significant proportion of patients who have MN-related genetic aberrations. During active inflammatory episodes, normal and leukemic hematopoieses are suppressed, which leads to the occurrence of aplastic cytopenia and leukemic cell regression. The successful treatment of underlying infections mitigates inflammatory stress-related antileukemic activities and promotes the penetration of leukemic hematopoiesis. The effect of IST is similar to that of treating underlying infections. Investigating inflammatory stress-powered antileukemic immunity is highly important in theoretical studies and clinical practice, especially given the wide application of immune-activating agents and immune checkpoint inhibitors in the treatment of hematological neoplasms.

Role of innate T cells in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a destructive gastrointestinal disease primarily affecting preterm babies. Despite advancements in neonatal care, NEC remains a significant cause of morbidity and mortality in neonatal intensive care units worldwide and the etiology of NEC is still unclear. Risk factors for NEC include prematurity, very low birth weight, feeding with formula, intestinal dysbiosis and bacterial infection. A review of the literature would suggest that supplementation of prebiotics and probiotics prevents NEC by altering the immune responses. Innate T cells, a highly conserved subpopulation of T cells that responds quickly to stimulation, develops differently from conventional T cells in neonates. This review aims to provide a succinct overview of innate T cells in neonates, encompassing their phenotypic characteristics, functional roles, likely involvement in the pathogenesis of NEC, and potential therapeutic implications.

The dynamic shifts of IL-10-producing Th17 and IL-17-producing Treg in health and disease: a crosstalk between ancient "Yin-Yang" theory and modern immunology

The changes in T regulatory cell (Treg) and T helper cell (Th) 17 ratios holds paramount importance in ensuring internal homeostasis and disease progression. Recently, novel subsets of Treg and Th17, namely IL-17-producing Treg and IL-10-producing Th17 have been identified. IL-17-producing Treg and IL-10-producing Th17 are widely considered as the intermediates during Treg/Th17 transformation. These "bi-functional" cells exhibit plasticity and have been demonstrated with important roles in multiple physiological functions and disease processes. Yin and Yang represent opposing aspects of phenomena according to the ancient Chinese philosophy "Yin-Yang" theory. Furthermore, Yin can transform into Yang, and vice versa, under specific conditions. This theory has been widely used to describe the contrasting functions of immune cells and molecules. Therefore, immune-activating populations (Th17, M1 macrophage, etc.) and immune overreaction (inflammation, autoimmunity) can be considered Yang, while immunosuppressive populations (Treg, M2 macrophage, etc.) and immunosuppression (tumor, immunodeficiency) can be considered Yin. However, another important connotation of "Yin-Yang" theory, the conversion between Yin and Yang, has been rarely documented in immune studies. The discovery of IL-17-producing Treg and IL-10-producing Th17 enriches the meaning of "Yin-Yang" theory and further promotes the relationship between ancient "Yin-Yang" theory and modern immunology. Besides, illustrating the functions of IL-17-producing Treg and IL-10-producing Th17 and mechanisms governing their differentiation provides valuable insights into the mechanisms underlying the dynamically changing statement of immune statement in health and diseases.

Chronic cold environment regulates rheumatoid arthritis through modulation of gut microbiota-derived bile acids

The pathologies of many diseases are influenced by environmental temperature. As early as the classical Roman age, people believed that exposure to cold weather was bad for rheumatoid arthritis (RA). However, there is no direct evidence supporting this notion, and the molecular mechanisms of the effects of chronic cold exposure on RA remain unknown. Here, in a temperature-conditioned environment, we found that chronic cold exposure aggravates collagen-induced arthritis (CIA) by increasing ankle swelling, bone erosion, and cytokine levels in rats. Furthermore, in chronic cold-exposed CIA rats, gut microbiota dysbiosis was identified, including a decrease in the differential relative abundance of the families Lachnospiraceae and Ruminococcaceae. We also found that an antibiotic cocktail suppressed arthritis severity under cold conditions. Notably, the fecal microbiota transplantation (FMT) results showed that transplantation of cold-adapted microbiota partly recapitulated the microbiota signature in the respective donor rats and phenocopied the cold-induced effects on CIA rats. In addition, cold exposure disturbed bile acid profiles, in particular decreasing gut microbiota-derived taurohyodeoxycholic acid (THDCA) levels. The perturbation of bile acids was also associated with activation of the TGR5-cAMP-PKA axis and NLRP3 inflammasome. Oral THDCA supplementation mitigated the arthritis exacerbation induced by chronic cold exposure. Our findings identify an important role of aberrant gut microbiota-derived bile acids in cold exposure-related RA, highlighting potential opportunities to treat cold-related RA by manipulating the gut microbiota and/or supplementing with THDCA.

The regulation of tissue-specific farnesoid X receptor on genes and diseases involved in bile acid homeostasis

Bile acids (BAs) facilitate the absorption of dietary lipids and vitamins and have also been identified as signaling molecules involved in regulating their own metabolism, glucose and lipid metabolism, as well as immunity. Disturbances in BA homeostasis are associated with various enterohepatic and metabolic diseases, such as cholestasis, nonalcoholic steatohepatitis, inflammatory bowel disease, and obesity. As a key regulator, the nuclear orphan receptor farnesoid X receptor (FXR, NR1H4) precisely regulates BA homeostasis by transcriptional regulation of genes involved in BA synthesis, metabolism, and enterohepatic circulation. FXR is widely regarded as the most potential therapeutic target. Obeticholic acid is the only FXR agonist approved to treat patients with primary biliary cholangitis, but its non-specific activation of systemic FXR also causes high-frequency side effects. In recent years, developing tissue-specific FXR-targeting drugs has become a research highlight. This article provides a comprehensive overview of the role of tissue-specific intestine/liver FXR in regulating genes involved in BA homeostasis and briefly discusses tissue-specific FXR as a therapeutic target for treating diseases. These findings provide the basis for the development of tissue-specific FXR modulators for the treatment of enterohepatic and metabolic diseases associated with BA dysfunction.

Houttuynia cordata thunb. alleviates inflammatory bowel disease by modulating intestinal microenvironment: a research review

Inflammatory bowel disease (IBD) is a complex group of chronic intestinal diseases, the cause of which has not yet been clarified, but it is widely believed that the disorder of the intestinal microenvironment and its related functional changes are key factors in the development of the disease. Houttuynia cordata thunb. is a traditional plant with abundant resources and long history of utilization in China, which has attracted widespread attention in recent years due to its potential in the treatment of IBD. However, its development and utilization are limited owing to the aristolochic acid alkaloids contained in it. Therefore, based on the relationship between the intestinal microenvironment and IBD, this article summarizes the potential mechanisms by which the main active ingredients of Houttuynia cordata thunb., such as volatile oils, polysaccharides, and flavonoids, and related traditional Chinese medicine preparations, such as Xiezhuo Jiedu Formula, alleviate IBD by regulating the intestinal microenvironment. At the same time, combined with current reports, the medicinal and edible safety of Houttuynia cordata thunb. is explained for providing ideas for further research and development of Houttuynia chordate thunb. in IBD disease, more treatment options for IBD patients, and more insights into the therapeutic potential of plants with homology of medicine and food in intestinal diseases, and even more diseases.

Insights into the liver-eyes connections, from epidemiological, mechanical studies to clinical translation

Maintenance of internal homeostasis is a sophisticated process, during which almost all organs get involved. Liver plays a central role in metabolism and involves in endocrine, immunity, detoxification and storage, and therefore it communicates with distant organs through such mechanisms to regulate pathophysiological processes. Dysfunctional liver is often accompanied by pathological phenotypes of distant organs, including the eyes. Many reviews have focused on crosstalk between the liver and gut, the liver and brain, the liver and heart, the liver and kidney, but with no attention paid to the liver and eyes. In this review, we summarized intimate connections between the liver and the eyes from three aspects. Epidemiologically, we suggest liver-related, potential, protective and risk factors for typical eye disease as well as eye indicators connected with liver status. For molecular mechanism aspect, we elaborate their inter-organ crosstalk from metabolism (glucose, lipid, proteins, vitamin, and mineral), detoxification (ammonia and bilirubin), and immunity (complement and inflammation regulation) aspect. In clinical application part, we emphasize the latest advances in utilizing the liver-eye axis in disease diagnosis and therapy, involving artificial intelligence-deep learning-based novel diagnostic tools for detecting liver disease and adeno-associated viral vector-based gene therapy method for curing blinding eye disease. We aim to focus on and provide novel insights into liver and eyes communications and help resolve existed clinically significant issues.

Metabolic Clues to Bile Acid Patterns and Prolonged Survival in Patients with Metastatic Soft-Tissue Sarcoma Treated with Trabectedin

Metastatic soft-tissue sarcomas (mSTS) encompass a highly heterogeneous group of rare tumours characterized by different clinical behaviours and outcomes. Currently, prognostic factors for mSTS are very limited, posing significant challenges in predicting patient survival. Within a cohort of 39 mSTS patients undergoing trabectedin treatment, it was remarkable to find one patient who underwent 73 cycles of trabectedin achieving an unforeseen clinical outcome. To identify contributing factors to her exceptional long-term survival, we have explored circulation metabolomics and biohumoral biomarkers to uncover a potential distinct host biochemical phenotype. The long-term survival patient compared with the other mSTS patients exhibited a distinctive metabolic profile characterized by remarkably higher levels of ursodeoxycholic acid (UDCA) derivatives and vitamin D and lower levels of lithocholic acid (LCA) derivatives, as well as reduced levels of inflammatory C-Reactive Protein 4 (C-RP4) biomarker. Despite its exploratory nature, this study reveals a potential association between specific bile acid metabolic profiles and mSTS patients' prognosis. Enhanced clinical understanding of the interplay between bile acid metabolism and disease progression could pave the way for new targeted therapeutic interventions which may improve the overall survival of mSTS patients.

Chronic Heat Stress Affects Bile Acid Profile and Gut Microbiota in Broilers

Heat stress (HS) can inhibit the growth performance of broilers and cause substantial economic losses. Alterations in bile acid (BA) pools have been reported to be correlated with chronic HS, yet the specific mechanism and whether it is related to gut microbiota remains unclear. In this study, 40 Rugao Yellow chickens were randomly selected and distributed into two groups (20 broilers in each group) when reaching 56-day age: a chronic heat stress group (HS, 36 ± 1 °C for 8 h per day in the first 7 days and 36 ± 1 °C for 24 h in the last 7 days) and a control group (CN, 24 ± 1 °C for 24 h within 14 days). Compared with the CN group, total BAs' serum content decreased, while cholic acid (CA), chenodeoxycholic acid (CDCA), and taurolithocholic acid (TLCA) increased significantly in HS broilers. Moreover, 12α-hydroxylase (CYP8B1) and bile salt export protein (BSEP) were upregulated in the liver, and the expression of fibroblast growth factor 19 (FGF19) decreased in the ileum of HS broilers. There were also significant changes in gut microbial composition, and the enrichment of Peptoniphilus was positively correlated with the increased serum level of TLCA. These results indicate that chronic HS disrupts the homeostasis of BA metabolism in broilers, which is associated with alterations in gut microbiota.