Akkermansia muciniphila protects mice against an emerging tick-borne viral pathogen

Bavachinin causes cholestasis by down-regulating BAAT expression and disrupting glycocholic acid synthesis in human liver organoids

Psoraleae Fructus (Bu Gu Zhi, BGZ) is extensively utilized for dermatological and osseous disorders in China. BGZ-induced liver injury has become one of the major concerns, which predominantly cause cholestasis, with the pathogenesis not being fully elucidated. Currently, studies on hepatotoxic mechanisms of BGZ have mainly been conducted on 2D cell culture systems or rodent models, which may not fully encapsulate human pathophysiology. Therefore, we generated human liver organoids (HLOs) from healthy donor(s) for living-related liver transplantation to explore the hepatotoxic mechanism. We identified bavachinin (BVC) as the most hepatotoxic component for cholestasis. After validating by CLF tests, we identified BVC caused cholestasis by down-regulating BAAT, which catalyzes the amidation of bile acids. We also found that up-regulating BAAT with harmaline could mitigate cholestasis and enhance cell viabilities in HLOs. We further demonstrated that glycocholic acid (GCA) levels decreased in BVC-treated HLOs. Supplementation of GCA to BVC-treated HLOs significantly improved cell viabilities. Collectively, our data suggested that BVC impaired the GCA synthesis by down-regulating the expression of BAAT, thereby inducing cholestasis.

Indole lactic acid derived from Akkermansia muciniphila activates the aryl hydrocarbon receptor to inhibit ferroptosis in ischemic stroke

Ischemic stroke concurrent with gut microbiome dysbiosis induces intestinal damage, which exacerbates cerebral infarction. Probiotic or prebiotic interventions that reverse gut microbiome dysbiosis can promote recovery after ischemic stroke. Akkermansia muciniphila (AKK) safeguards intestinal health and is a promising probiotic; however, its role in ischemic stroke remains unclear. In this study, we found that live AKK, but not pasteurized AKK, mitigated ischemic-stroke-induced neurological injury, reduced cerebral infarction, and enhanced both blood-brain and intestinal barrier integrity. Moreover, the AKK supernatant reduced intestinal and cerebral injury, demonstrating efficacy comparable to that of live AKK. Metabolomic analysis revealed that the AKK supernatant was significantly enriched in indole lactic acid (ILA), a tryptophan metabolite. ILA levels were elevated in the serum and brains of pseudo-germ-free stroke rats administered AKK. Exogenous gavage with ILA mitigated ischemic-stroke-induced brain and intestinal damage. Mechanistically, ILA activated the aryl hydrocarbon receptor (AhR) and the nuclear transcription factor Nrf2, leading to the upregulation of SLC7A11 and GPX4 protein expression. This attenuated lipid peroxidation and intracellular iron accumulation triggered by ischemic stroke. Notably, intervention with the AhR inhibitor CH223191 abrogated the protective effects of ILA in ischemic stroke rats. These findings suggest that the therapeutic efficacy of AKK in ischemic stroke is at least partially attributable to ILA-mediated ferroptosis inhibition via AhR activation. AKK was selectively enriched by Puerariae lobatae Radix-resistant starch (PRS), promoting ILA generation more effectively than inulin and β-glucan. AKK and PRS synergistically alleviated ischemic-stroke-induced impairments, outperforming monomicrobial or prebiotic treatment alone. These findings reveal the unique mechanisms of AKK in ischemic stroke and provide a viable strategy for the clinical treatment of ischemic stroke through a novel synbiotic combination.

Lactobacillus plantarum reduces polystyrene microplastic induced toxicity via multiple pathways: A potentially effective and safe dietary strategy to counteract microplastic harm

Plastic materials, ubiquitous in daily life, degrade into microplastics (MPs) that can accumulate in humans through the food chain, leading to health issues. While some antioxidants have been shown to mitigate the toxicity caused by MPs exposure, they are only effective at high doses, which can be harmful to human health when ingested in excess. Concurrently, Lactobacillus species have demonstrated the ability to adsorb onto micro- and nano-plastics (MNPs), with certain strains exhibiting high antioxidant activity. In this study, Lactobacillus plantarum strains with varying antioxidant capacities and affinities for polystyrene nanoparticles (PS-NPs) were utilized to investigate their effects on toxicity induced by exposure to PS-MPs. The results indicated that the antioxidant capabilities of Lactobacillus plantarum can reduce oxidative damage caused by PS-MPs exposure, and their ability to bind with PS-MNPs can reduce the body's PS-MPs content and increase fecal PS-MPs content, thereby reducing toxicity. Notably, the strain 89-L1, which possesses low antioxidant activity and low binding affinity for PS-MNPs, also reduced toxicity, potentially through repairing the intestinal barrier and modulating bile acid (BAs) metabolism. Our findings suggest that the mechanisms by which Lactobacillus plantarum reduces PS-MPs-induced toxicity extend beyond antioxidant and binding capabilities; the repair of the intestinal barrier and modulation of BAs metabolism also play significant roles in reducing toxicity caused by PS-MPs exposure and may act partially independently of these capacities. This study provides a theoretical basis for the future development of strategies for Lactobacillus plantarum to reduce toxicity caused by exposure to MPs.

Enterococcus faecalis Exerts Neuroprotective Effects via the Vagus Nerve in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disease worldwide. Current treatment methods for PD are unable to halt disease progression. The gut microbiota contributes to the neurodevelopment of PD; however, the gut-brain connections and underlying neural bases that regulate this complex behavior are not yet clear. Enterococcus faecalis (EF) is a common commensal bacterium of the gut and a common pathogen associated with hospital-acquired infections. Here, we demonstrated the significant therapeutic effects of a non-pathogenic strain of EF (EF ATCC19433) on PD. In this study, we established a mouse model of PD by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We found that EF treatment alleviated behavioral impairment, dopaminergic neuronal loss, blood-brain barrier damage, and neuroinflammation induced by MPTP in the mice. Additionally, 16S rRNA sequencing revealed that dysbiosis of PD-related microbial communities induced by MPTP was reversed by EF treatment. Moreover, EF treatment relieved gastrointestinal dysfunction in the mice. The therapeutic efficacy of EF in MPTP-induced PD mice is markedly diminished when the activity of EF is lost. Further mechanistic studies indicated that the neuroprotective effects of EF in PD were associated with the vagus nerve pathway. Following the surgical severance of the vagus nerve through subdiaphragmatic vagotomy, the protective effects of EF on PD were markedly diminished. Our study suggests that EF can alleviate neurofunctional impairments and gastrointestinal disorders associated with PD, indicating that gut-derived microbes influence brain function through the vagus nerve pathway.

Alterations of the gut commensal akkermansia muciniphila in patients with COVID-19

Dysbiosis of gut microbiota is well established in coronavirus disease 2019 (COVID-19). While studies have attempted to establish a link between the gut commensal Akkermansia muciniphila (A. muciniphila) and COVID-19, the findings have been inconsistent and sometimes controversial. The intestinal microbial abundance information of COVID-19 patients was acquired and analysed from GMrepo database. Subsequently, A. muciniphila's metabolites, target-genes, and metabolite-target relationships was extracted from GutMGene database. Lastly, coronascape module in Metascape database is used for gene annotation and enrichment analysis in various host cells and tissues after SARS-CoV-2 infection. The results indicated that, in comparison to the health people, A. muciniphila was significantly elevated in COVID-19 patients. This bacterium was found to be associated with heightened expression of IL-10, TLR2, TLR4, CLGN, CLDN4, TJP2, and TJP3, while concurrently experiencing a reduction in the expression of IL-12A and IL-12B in humans. The regulatory genes of A. muciniphila primarily enhance responses to viruses and cytokines, positively regulate cell migration, and control epithelial cell proliferation. Our study revealed a significant increase in the gut commensal A. muciniphila in COVID-19 patients. This bacterium can modulate host immune responses and may also serve as a probiotic with antiviral properties.

Metabolic Profiling Reveals Potential Prognostic Biomarkers for SFTS: Insights into Disease Severity and Clinical Outcomes

Background/Objectives: Severe fever with thrombocytopenia syndrome (SFTS) is a viral infection primarily found in Asia, with a case fatality rate of about 10%. Despite its increasing prevalence, the underlying pathogenic mechanisms remain poorly understood, limiting the development of effective therapeutic interventions. Methods: We employed an untargeted metabolomics approach using liquid chromatography-mass spectrometry (LC-MS) to analyze serum samples from 78 SFTS patients during the acute phase of their illness. Differential metabolic features between survival and fatal cases were identified through multivariate statistical analysis. Furthermore, we constructed a metabolic prognostic model based on these biomarkers to predict disease severity. Results: Significant alterations were observed in four key metabolic pathways: sphingolipid metabolism, biosynthesis of phenylalanine, tyrosine, and tryptophan, primary bile acid biosynthesis, and phenylalanine metabolism. Elevated levels of phenyllactic acid and isocitric acid were strongly associated with adverse outcomes and demonstrated high discriminatory power in distinguishing fatal cases from survivors. The metabolic prognostic model incorporating these biomarkers achieved a sensitivity of 75% and a specificity of 90% in predicting disease severity. Conclusions: Our findings highlight the pivotal role of metabolic dysregulation in the pathogenesis of SFTS and suggest that targeting specific metabolic pathways could open new avenues for therapeutic development. The identification of prognostic biomarkers provides a valuable tool for early risk stratification and timely clinical intervention, potentially improving patient outcomes.

Short-term and long-term high-fat diet promote metabolic disorder through reprogramming mRNA m6A in white adipose tissue by gut microbiota

BACKGROUND

Although short-term high-fat diet (S-HFD) and long-term high-fat diet (L-HFD) induce metabolic disorder, the underlying epigenetic mechanism is still unclear.

RESULTS

Here, we found that both 4 days of S-HFD and 10 weeks of L-HFD increased mRNA m6A level in epididymal white adipose tissue (eWAT) and impaired metabolic health. Interestingly, S-HFD activated transposable elements (TEs), especially endogenous retroviruses (ERVs) in eWAT, while L-HFD activated long interspersed elements (LINEs). Subsequently, we demonstrated that both S-HFD and L-HFD increased m6A level of Ehmt2 and decreased EHMT2 protein expression and H3K9me2 level, accounting for activation of ERVs and LINEs. Overexpression of EHMT2 in eWAT or inhibition of ERVs and LINEs by antiviral therapy improved metabolic health under HFD feeding. Notably, we found that both short-term and long-term HFD feeding increased Fimicutes/Bacteroidota ratio and decreased the gut microbiome health index. Fecal microbiota transplantation (FMT) experiments demonstrated that gut microbiota from S-HFD and L-HFD was responsible for increased m6A level in eWAT, resulting in glucose intolerance and insulin insensitivity. Furthermore, we identified that both S-HFD and L-HFD increased the abundance of the gut microbial metabolite homogentisic acid (HGA), and HGA level was positively correlated with unclassified_f__Lachnospiraceae which was both increased in S-HFD and L-HFD feeding mice. Administration of HGA increased the m6A level of Ehmt2 and decreased the EHMT2 protein expression and H3K9me2 level in eWAT, leading to metabolic disorder in mice.

CONCLUSIONS

Together, this study reveals a novel mechanism that S-HFD and L-HFD induce metabolism disorder through gut microbiota-HGA-m6A-Ehmt2-ERV/LINE signaling. These findings may provide a novel insight for prevention and treatment of metabolism disorder upon short-term or long-term dietary fat intake. Video Abstract.

The worldview of Akkermansia muciniphila, a bibliometric analysis

Akkermansia muciniphila (A. muciniphila), a critical bacterium within the gut microbiota, plays a key role in human health and immunomodulation. Since its identification in 2004, A. muciniphila has emerged as a significant agent in treating metabolic diseases, gastroenterological diseases, and tumor immunotherapy. Its rapid ascent in scientific translation underscores its importance in gut microbiome research. However, there has been a lack of visualization and analysis of the rapidly occurring commercialization in this field, which has critically hindered insights into the current knowledge structure and understanding of the cutting-edge of the discipline. This study employs the Web of Science Core Collection (WOSCC) and Innography platforms to provide the first comprehensive analysis of A. muciniphila's academic progresses and commercialization over the past two decades, highlighting its growing prominence in global health research. Our analysis delineates that, following the academic trajectory, the evolution of A. muciniphila patents from foundational research through to application development and maturity, with particular emphasis on its expansive potential in emerging fields, including gastroenterological disorders, non-alcoholic fatty liver disease, cancer immunotherapy, stress management, and neurodegenerative disease treatment. Concluding, A. muciniphila presents as a next-generation probiotic with vast implications for human health. Our findings provide essential insights for future research and product development, contributing to the advancement of this burgeoning field.

Quercetin-Driven Akkermansia Muciniphila Alleviates Obesity by Modulating Bile Acid Metabolism via an ILA/m6A/CYP8B1 Signaling

Global health is increasingly challenged by the growing prevalence of obesity and its associated complications. Quercetin, one of the most important dietary flavonoids, is being explored as an effective therapy for obesity with its mechanism remains understudied. Here in this study, it is demonstrated that quercetin intervention significantly reverses obesity-related phenotypes through reshaping the overall structure of microbiota, especially boosting colonization of the beneficial gut commensal Akkermansia muciniphila (A. muciniphila). Enrichment of A. muciniphila leads to generate more indole-3-lactic acid (ILA) to upregulate the expression of 12α-hydroxylase (CYP8B1) via fat mass and obesity-associated protein (FTO)/ N6-methyladenosine (m6A)/YTHDF2 manner, thereby facilitating cholesterol converts to cholic acid (CA). CA in turn drastically suppresses lipid accumulation via activating the farnesoid X receptor (FXR) in adipose tissue. This work introduces a novel therapeutic target for addressing obesity and expands upon the current limited understanding of the mediator function of m6A modifications in microorganism-influenced bile acid (BA) metabolism.

Development of a novel multi-epitope mRNA vaccine candidate to combat SFTSV pandemic

Severe Fever with Thrombocytopenia Syndrome virus (SFTSV) is a novel identified pathogen, despite two decades of research on SFTSV, the potential widespread threats pose a significant challenge for researchers in developing new treatment and prevention methods. In this present, we have developed a multi-epitope mRNA vaccine for SFTSV and valid it with in silico methods. We screened 9 immunodominant epitopes for cytotoxic T cells (CTL), 7 for helper T cells (HTL), and 8 for Linear B-cell (LBL) based on promising candidate protein Gn, Gc, Np, and NSs. All predicted epitopes demonstrated strong antigenicity without any potential harm to humans. Additionally, the high conservancy is required to cover different strains. All epitopes as well as adjuvants were constructed into a final vaccine, which was further assesd by calculating of physicochemical properties. Then, we docked the vaccine protein with immune receptors and analyzed the complexes with dynamic simulations to evaluate its affinity to receptors. Finally, the vaccine sequence was constructed into a mRNA sequence. The constructed vaccine is a potential candidate for combating SFTSV by stimulating protective humoral and cellular immune responses.

Neuroprotective Effects of Paeonia lactiflora Through the Regulation of Gut Dubosiella in an MPTP-Induced Parkinson's Disease Mouse Model

Emerging evidence suggests that changes in the composition of the gut microbiota may play an important role in the pathogenesis of Parkinson's disease (PD). Paeonia lactiflora Pall., a traditional Chinese medicinal herb belonging to the genus Paeonia, is commonly used in Chinese medicinal practice for the treatment of PD. However, the specific mechanisms of its action remain poorly understood. This study aimed to further determine the neuroprotective properties of Paeonia lactiflora Pall. water extract (PWE) in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model, and to investigate its potential implications for the pathogenesis of PD. A PD mouse model was established via the intraperitoneal administration of MPTP, followed by the assessment of motor function using behavioral tests. Western blotting and histopathological analysis were used to measure the levels of dopaminergic (DAergic) neurodegeneration-related factors in the midbrain (containing the substantia nigra (SN)) and striatum. 16S rRNA gene sequencing and metabolomic analysis were applied to identify differences in the gut microbiota and metabolites, respectively. Our results indicate that PWE effectively protects against MPTP-induced motor deficits, loss of DAergic neurons, blood-brain barrier (BBB) damage, and neuroinflammation in PD. The protective effects of PWE against PD are mediated through modulation of the gut microbiota, specifically by an increase in the abundance of the genus Dubosiella. In this study, we selected D. newyorkensis as a representative strain of the genus, and determined its therapeutic effects in an MPTP-induced PD mouse model. Our preliminary findings suggest that the neuroprotective effects of D. newyorkensis may be related to the production of serum indoleacetic acid.

Conjugated bile acids alleviate acute pancreatitis through inhibition of TGR5 and NLRP3 mediated inflammation

INTRODUCTION

Severe acute pancreatitis (SAP) is a crucial gastrointestinal disease characterized by systemic inflammatory responses and persistent multiple organ failure. The role of bile acids (BAs) in diverse inflammatory diseases is increasingly recognized as crucial, but the underlying role of BA conjugation remains elusive.

OBJECTIVES

Our study aim to investigate the potential role of conjugated bile acids in SAP and reveal the molecular mechanisms underlying its regulatory effects. We hypothesized that taurochenodeoxycholic acid (TCDCA) and glycochenodeoxycholic acid (GCDCA) could protect SAP through inhibiting the activation of NLRP3 inflammasomes via the TGR5 pathway in macrophages.

METHODS

To test our hypothesis, we used BA-CoA: amino acid N-acyltransferase knockout (Baat-/-) mice and established SAP mouse models using caerulein- and sodium taurocholate- induced. We utilized a range of methods, including pathology sections, qRT-PCR, immunofluorescence, Western blotting, and ELISA, to identify the mechanisms of regulation.

RESULTS

BA-CoA: Amino acid N-acyltransferase knockout (Baat-/-) mice significantly exacerbated pancreatitis by increasing pancreatic and systemic inflammatory responses and pancreatic damage in SAP mouse models. Moreover, the serum TCDCA levels in Baat-/- mice were lower than those in wild-type (WT) mice with or without SAP, and GCDCA and TCDCA showed stronger anti-inflammatory effects than chenodeoxycholic acid (CDCA) in vitro. TCDCA treatment alleviated SAP in a Takeda G protein-coupled receptor 5 and NOD-like receptor family, pyrin domain containing 3-dependent manner in vivo. Reinforcing our conclusions from the mouse study, clinical SAP patients exhibited decreased serum content of conjugated BAs, especially GCDCA, which was inversely correlated with the severity of systemic inflammatory responses.

CONCLUSION

Conjugated bile acids significantly inhibit NLRP3 inflammasome activation by activating TGR5 pathway, thereby alleviating pancreatic immunopathology. The results provide new insights into the variability of clinical outcomes and paves the way for developing more effective therapeutic interventions for AP.

Current insights into human pathogenic phenuiviruses and the host immune system

Phenuiviruses are a class of segmented negative-sense single-stranded RNA viruses, typically consisting of three RNA segments that encode four distinct proteins. The emergence of pathogenic phenuivirus strains, such as Rift Valley fever phlebovirus (RVFV) in sub-Saharan Africa, Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV) in East and Southeast Asia, and Heartland Virus (HRTV) in the United States has presented considerable challenges to global public health in recent years. The innate immune system plays a crucial role as the initial defense mechanism of the host against invading pathogens. In addition to continued research aimed at elucidating the epidemiological characteristics of phenuivirus, significant advancements have been made in investigating its viral virulence factors (glycoprotein, non-structural protein, and nucleoprotein) and potential host-pathogen interactions. Specifically, efforts have focused on understanding mechanisms of viral immune evasion, viral assembly and egress, and host immune networks involving immune cells, programmed cell death, inflammation, nucleic acid receptors, etc. Furthermore, a plethora of technological advancements, including metagenomics, metabolomics, single-cell transcriptomics, proteomics, gene editing, monoclonal antibodies, and vaccines, have been utilized to further our understanding of phenuivirus pathogenesis and host immune responses. Hence, this review aims to provide a comprehensive overview of the current understanding of the mechanisms of host recognition, viral immune evasion, and potential therapeutic approaches during human pathogenic phenuivirus infections focusing particularly on RVFV and SFTSV.

Vaginal lactobacilli produce anti-inflammatory β-carboline compounds

The optimal vaginal microbiome is a Lactobacillus-dominant community. Apart from Lactobacillus iners, the presence of Lactobacillus species is associated with reduced vaginal inflammation and reduced levels of pro-inflammatory cytokines. Loss of Lactobacillus-dominance is associated with inflammatory conditions, such as bacterial vaginosis (BV). We have identified that Lactobacillus crispatus, a key vaginal bacterial species, produces a family of β-carboline compounds with anti-inflammatory activity. These compounds suppress nuclear factor κB (NF-κB) and interferon (IFN) signaling downstream of multiple pattern recognition receptors in primary human cells and significantly dampen type I IFN receptor (IFNAR) activation in monocytes. Topical application of an anti-inflammatory β-carboline compound, perlolyrine, was sufficient to significantly reduce vaginal inflammation in a mouse model of genital herpes infection. These compounds are enriched in cervicovaginal lavage (CVL) of healthy people compared with people with BV. This study identifies a family of compounds by which vaginal lactobacilli mediate host immune homeostasis and highlights a potential therapeutic avenue for vaginal inflammation.

Intermittent Fasting Improves Insulin Resistance by Modulating the Gut Microbiota and Bile Acid Metabolism in Diet-Induced Obesity

SCOPE

Adipose tissue macrophages (ATMs) are crucial in the pathogenesis of insulin resistance (IR). Intermittent fasting (IF) is an effective intervention for obesity. However, the underlying mechanism by which IF improves IR remains unclear.

METHODS AND RESULTS

Male C57BL/6J mice are fed chow-diet and high-fat diet (HFD) for 12 weeks, then is randomized into ad libitum feeding or every other day fasting for 8 weeks. Markers of ATMs and expression of uncoupling protein 1 (UCP-1) are determined. Gut microbiota and bile acids (BAs) are profiled using 16S rRNA sequencing and targeted metabolomics analysis. Results indicate that IF improves IR in HFD-induced obesity. IF decreases ATM infiltration, pro-inflammatory M1 gene expression, and promotes white adipose tissue (WAT) browning by elevating UCP-1 expression. IF restructures microbiota composition, significantly expanding the abundance of Verrucomicrobia particularly Akkermansia muciniphila, with the decrease of that of Firmicutes. IF increases the level of total BAs and alters the composition of BAs with higher proportion of 12α-hydroxylated (12α-OH) BAs. The changes in these BAs are correlated with differential bacteria.

CONCLUSION

The findings indicate that IF improves IR partially mediated by the interplay between restructured gut microbiota and BAs metabolism, which has implications for the dietary management in obesity.

Postbiotics are a candidate for new functional foods

Accumulating studies have highlighted the great potential of postbiotics in alleviating diseases and protecting host health. Compared with traditional functional foods (such as probiotics and prebiotics), postbiotics have the advantages of a single composition, high physiological activity, long shelf life, easy absorption, and high targeting, etc. The development of postbiotics has led to a wide range of potential applications in functional food and drug development. However, the lack of clinical trial data, mechanism analyses, safety evaluations, and effective regulatory frameworks has limited the application of postbiotic products. This review describes the definition, classification, sources, and preparation methods of postbiotics, the progress and mechanism of preclinical and clinical research in improving host diseases, and their application in food. Strengthen understanding of the recognition and development of related products to lay a theoretical foundation.

Taurolithocholic acid protects against viral haemorrhagic fever via inhibition of ferroptosis

Bile acids are microbial metabolites that can impact infection of enteric and hepatitis viruses, but their functions during systemic viral infection remain unclear. Here we show that elevated levels of the secondary bile acid taurolithocholic acid (TLCA) are associated with reduced fatality rates and suppressed viraemia in patients infected with severe fever with thrombocytopenia syndrome virus (SFTSV), an emerging tick-borne haemorrhagic fever virus. TLCA inhibits viral replication and mitigates host inflammation during SFTSV infection in vitro, and indirectly suppresses SFTSV-mediated induction of ferroptosis by upregulating fatty acid desaturase 2 via the TGR5-PI3K/AKT-SREBP2 axis. High iron and ferritin serum levels during early infection were correlated with decreased TLCA levels and fatal outcomes in SFTSV-infected patients, indicating potential biomarkers. Furthermore, treatment with either ferroptosis inhibitors or TLCA protected mice from lethal SFTSV infection. Our findings highlight the therapeutic potential of bile acids to treat haemorrhagic fever viral infection.

STING-mediated IL-6 Inhibits OATP1B1 Expression via the TCF4 Signaling Pathway in Cholestasis

BACKGROUND AND AIMS

Organic anion-transporting polypeptides (OATPs) play a crucial role in the transport of bile acids and bilirubin. In our previous study, interleukin 6 (IL-6) reduced OATP1B3 levels in cholestatic disease. However, it remains unclear whether IL-6 inhibits OATP1B1 expression in cholestatic diseases. This study aimed to investigate whether IL-6 can inhibit OATP1B1 expression and explore the underlying mechanisms.

METHODS

The effect of stimulator of interferon genes (STING) signaling on inflammatory factors was investigated in a cholestatic mouse model using RT-qPCR and enzyme-linked immunosorbent assay. To assess the impact of inflammatory factors on OATP1B1 expression in hepatocellular carcinoma, we analyzed OATP1B1 expression by RT-qPCR and Western Blot after treating PLC/PRF/5 cells with TNF-α, IL-1β, and IL-6. To elucidate the mechanism by which IL-6 inhibits OATP1B1 expression, we examined the expression of the OATP1B1 regulator TCF4 in PLC/PRF/5 and HepG2 cells using RT-qPCR and Western Blot. The interaction mechanism between β-catenin/TCF4 and OATP1B1 was investigated by knocking down β-catenin/TCF4 through siRNA transfection.

RESULTS

The STING inhibitor decreased inflammatory factor levels in the cholestatic mouse model, with IL-6 exhibiting the most potent inhibitory effect on OATP1B1. IL-6 downregulated β-catenin/TCF4, leading to decreased OATP1B1 expression. Knocking-down β-catenin/TCF4 counteracted the β-catenin/TCF4-mediated repression of OATP1B1.

CONCLUSIONS

STING-mediated IL-6 up-regulation may inhibit OATP1B1, leading to reduced transport of bile acids and bilirubin by OATP1B1. This may contribute to altered pharmacokinetics in patients with diseases associated with increased IL-6 production.

Role of gut microbiota in Crohn's disease pathogenesis: Insights from fecal microbiota transplantation in mouse model

BACKGROUND

Inflammatory bowel disease, particularly Crohn's disease (CD), has been associated with alterations in mesenteric adipose tissue (MAT) and the phenomenon termed "creeping fat". Histopathological evaluations showed that MAT and intestinal tissues were significantly altered in patients with CD, with these tissues characterized by inflammation and fibrosis.

AIM

To evaluate the complex interplay among MAT, creeping fat, inflammation, and gut microbiota in CD.

METHODS

Intestinal tissue and MAT were collected from 12 patients with CD. Histological manifestations and protein expression levels were analyzed to determine lesion characteristics. Fecal samples were collected from five recently treated CD patients and five control subjects and transplanted into mice. The intestinal and mesenteric lesions in these mice, as well as their systemic inflammatory status, were assessed and compared in mice transplanted with fecal samples from CD patients and control subjects.

RESULTS

Pathological examination of MAT showed significant differences between CD-affected and unaffected colons, including significant differences in gut microbiota structure. Fetal microbiota transplantation (FMT) from clinically healthy donors into mice with 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced CD ameliorated CD symptoms, whereas FMT from CD patients into these mice exacerbated CD symptoms. Notably, FMT influenced intestinal permeability, barrier function, and levels of proinflammatory factors and adipokines. Furthermore, FMT from CD patients intensified fibrotic changes in the colon tissues of mice with TNBS-induced CD.

CONCLUSION

Gut microbiota play a critical role in the histopathology of CD. Targeting MAT and creeping fat may therefore have potential in the treatment of patients with CD.

The influence of Akkermansia muciniphila on intestinal barrier function

Intestinal barriers play a crucial role in human physiology, both in homeostatic and pathological conditions. Disruption of the intestinal barrier is a significant factor in the pathogenesis of gastrointestinal inflammatory diseases, such as inflammatory bowel disease. The profound influence of the gut microbiota on intestinal diseases has sparked considerable interest in manipulating it through dietary interventions, probiotics, and fecal microbiota transplantation as potential approaches to enhance the integrity of the intestinal barrier. Numerous studies have underscored the protective effects of specific microbiota and their associated metabolites. In recent years, an increasing body of research has demonstrated that Akkermansia muciniphila (A. muciniphila, Am) plays a beneficial role in various diseases, including diabetes, obesity, aging, cancer, and metabolic syndrome. It is gaining popularity as a regulator that influences the intestinal flora and intestinal barrier and is recognized as a 'new generation of probiotics'. Consequently, it may represent a potential target and promising therapy option for intestinal diseases. This article systematically summarizes the role of Am in the gut. Specifically, we carefully discuss key scientific issues that need resolution in the future regarding beneficial bacteria represented by Am, which may provide insights for the application of drugs targeting Am in clinical treatment.

The first diagnosis of Severe Fever with Thrombocytopenia Syndrome caused by tick-borne Severe Fever with Thrombocytopenia Syndrome virus in Chongqing, China: A case report and literature review

BACKGROUND

Severe Fever with Thrombocytopenia Syndrome (SFTS) is a tick-borne disease caused by the SFTS virus (SFTSV) which has the potential to become a pandemic and is currently a major public health concern.

CASE PRESENTATION

We present the case of a 74-year-old female from an urban area of Chongqing, with leukocytopenia, thrombocytopenia, organ function, inflammatory, blood coagulation, and immune abnormalities. SFTSV infection was confirmed through molecular detection and metagenomic next-generation sequencing (mNGS) analysis, indicating a diagnosis of SFTS due to the patient's history of tick bites. The patient received symptomatic and supportive therapy, including antibiotics, antiviral treatment, and antifungal therapy, and finally discharged from the hospital on day 18.

CONCLUSIONS

This study highlights the need for increased awareness, early diagnosis, and prompt treatment for tick-borne SFTS. It also provides a comprehensive understanding of the disease's characteristics, pathogenesis, detection methods, and available treatments.

Anti-inflammatory action of silver nanoparticles in vivo: systematic review and meta-analysis

The aim of this study was to systematically review the literature to investigate whether silver nanoparticles (AgNPs) have an anti-inflammatory effect in vivo. The guidelines of PRISMA were applied, and a registration was made in PROSPERO. A personalized search of the PubMed, Web of Science, Scopus, Embase, Lilacs, and Google Scholar databases was conducted in September 2023. For the data analysis, the inverse variance in the random effects model was used. The tools of SYRCLE and GRADE were used to assess the risk of bias and the certainty of evidence, respectively. From the 9185 identified studies, 5685 duplicate studies were excluded; 52 were read in full text, and 7 were included in this review. Six studies were evaluated by the meta-analysis, and an increase in anti-inflammatory molecules (SMD -5.22; PI [-6.50, -3.94]) and an increase in anti-inflammatory ones (SMD 5.75; PI [3.79, 7.72]) were observed. Qualitative analysis showed a reduction in pro-inflammatory proteins and in the COX-2 pathway. It was concluded that AgNPs present an anti-inflammatory action in vivo through mechanisms involving the reduction of pro-inflammatory molecules and proteins, the increase of anti-inflammatory molecules, and selective inhibition of the COX-2 pathway.

Ginsenoside Rh4 inhibits colorectal cancer via the modulation of gut microbiota-mediated bile acid metabolism

INTRODUCTION

Dysbiosis of the gut microbiota is emerging as a pivotal factor in the pathogenesis of colorectal cancer (CRC). Ginsenoside Rh4 (Rh4) is an active compound isolated from ginseng with beneficial effects in modulating intestinal inflammation and gut microbiota dysbiosis, but how Rh4 regulates the gut microbiota to alleviate CRC remains underexplored.

OBJECTIVES

We investigated the impact of Rh4 on CRC and the mechanism of its action in inhibiting CRC via modulation of gut microbiota.

METHODS

We used the AOM/DSS model and employed transcriptomics, genomics and metabolomics techniques to explore the inhibitory impact of Rh4 on CRC. Furthermore, we employed experiments involving antibiotic treatment and fecal microbiota transplantation (FMT) to investigate the role of the gut microbiota. Finally, we elucidated the pivotal role of key functional bacteria and metabolites regulated by Rh4 in CRC.

RESULTS

Our research findings indicated that Rh4 repaired intestinal barrier damage caused by CRC, alleviated intestinal inflammation, and inhibited the development of CRC. Additionally, Rh4 inhibited CRC in a gut microbiota-dependent manner. Rh4 increased the diversity of gut microbiota, enriched the probiotic Akkermansia muciniphila (A. muciniphila), and alleviated gut microbiota dysbiosis caused by CRC. Subsequently, Rh4 regulated A. muciniphila-mediated bile acid metabolism. A. muciniphila promoted the production of UDCA by enhancing the activity of 7α-hydroxysteroid dehydrogenase (7α-HSDH). UDCA further activated FXR, modulated the TLR4-NF-κB signaling pathway, thus inhibiting the development of CRC.

CONCLUSION

Our results confirm that Rh4 inhibits CRC in a gut microbiota-dependent manner by modulating gut microbiota-mediated bile acid metabolism and promoting the production of UDCA, which further activates the FXR receptor and regulates the TLR4-NF-κB signaling pathway. Our results confirm that Rh4 has the potential to be used as a modulator of gut microbiota for preventing and treatment of CRC.

Intestinal linoleic acid contributes to the protective effects of Akkermansia muciniphila against Listeria monocytogenes infection in mice

Akkermansia muciniphila pretreatment mitigated Listeria monocytogenes infection in mice. A. muciniphila improved gut microbiota disturbed by L. monocytogenes infection and significantly increased the level of intestinal linoleic acid in mice. Linoleic acid strengthened the intestinal epithelial barrier and reduced pathogen translocation partly by regulating NF-κB/MLCK pathway in a GPR40-dependent manner.

Diet-driven differential response of Akkermansia muciniphila modulates pathogen susceptibility

The erosion of the colonic mucus layer by a dietary fiber-deprived gut microbiota results in heightened susceptibility to an attaching and effacing pathogen, Citrobacter rodentium. Nevertheless, the questions of whether and how specific mucolytic bacteria aid in the increased pathogen susceptibility remain unexplored. Here, we leverage a functionally characterized, 14-member synthetic human microbiota in gnotobiotic mice to deduce which bacteria and functions are responsible for the pathogen susceptibility. Using strain dropouts of mucolytic bacteria from the community, we show that Akkermansia muciniphila renders the host more vulnerable to the mucosal pathogen during fiber deprivation. However, the presence of A. muciniphila reduces pathogen load on a fiber-sufficient diet, highlighting the context-dependent beneficial effects of this mucin specialist. The enhanced pathogen susceptibility is not owing to altered host immune or pathogen responses, but is driven by a combination of increased mucus penetrability and altered activities of A. muciniphila and other community members. Our study provides novel insights into the mechanisms of how discrete functional responses of the same mucolytic bacterium either resist or enhance enteric pathogen susceptibility.

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.

The discovery of regional neurotoxicity-associated metabolic alterations induced by carbon quantum dots in brain of mice using a spatial metabolomics analysis

BACKGROUND

Recently, carbon quantum dots (CQDs) have been widely used in various fields, especially in the diagnosis and therapy of neurological disorders, due to their excellent prospects. However, the associated inevitable exposure of CQDs to the environment and the public could have serious severe consequences limiting their safe application and sustainable development.

RESULTS

In this study, we found that intranasal treatment of 5 mg/kg BW (20 µL/nose of 0.5 mg/mL) CQDs affected the distribution of multiple metabolites and associated pathways in the brain of mice through the airflow-assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI) technique, which proved effective in discovery has proven to be significantly alerted and research into tissue-specific toxic biomarkers and molecular toxicity analysis. The neurotoxic biomarkers of CQDs identified by MSI analysis mainly contained aminos, lipids and lipid-like molecules which are involved in arginine and proline metabolism, biosynthesis of unsaturated fatty acids, and glutamine and glutamate metabolism, etc. as well as related metabolic enzymes. The levels or expressions of these metabolites and enzymes changed by CQDs in different brain regions would induce neuroinflammation, organelle damage, oxidative stress and multiple programmed cell deaths (PCDs), leading to neurodegeneration, such as Parkinson's disease-like symptoms. This study enlightened risk assessments and interventions of QD-type or carbon-based nanoparticles on the nervous system based on toxic biomarkers regarding region-specific profiling of altered metabolic signatures.

CONCLUSION

These findings provide information to advance knowledge of neurotoxic effects of CQDs and guide their further safety evaluation.

Multiomics analysis investigating the impact of a high-fat diet in female Sprague-Dawley rats: alterations in plasma, intestinal metabolism, and microbial composition

Introduction

With improvements in living conditions, modern individuals exhibit a pronounced inclination towards a high-fat diet, largely because of its distinctive gustatory appeal. However, the association between high-fat diets and metabolic complications has largely been ignored, and metabolic diseases such as obesity and non-alcoholic fatty liver disease now constitute a major public health concern. Because high-fat diets increase the risk of metabolic diseases, a thorough investigation into the impact of high-fat diets on gut microbiota and metabolism is required.

Methods

We utilize 16S rRNA sequencing and untargeted metabolomics analysis to demonstrate that SD rats fed a high-fat diet exhibited marked alterations in gut microbiota and plasma, intestinal metabolism.

Results

Changes in gut microbiota included a decreased abundance at phylum level for Verrucomicrobiota, and a decreased abundance at genus level for Akkermansia, Ralstonia, Bacteroides, and Faecalibacterium. Additionally, significant changes were observed in both intestinal and plasma metabolite levels, including an upregulation of bile acid metabolism, an upregulation of glucose-lipid metabolism, and increased levels of metabolites such as norlithocholic acid, cholic acid, D-fructose, D-mannose, fructose lactate, and glycerophosphocholine. We also investigated the correlations between microbial communities and metabolites, revealing a significant negative correlation between Akkermansia bacteria and cholic acid.

Discussion

Overall, our findings shed light on the relationship between symbiotic bacteria associated with high-fat diets and metabolic biomarkers, and they provide insights for identifying novel therapeutic approaches to mitigate disease risks associated with a high-fat diet.

Restoration of Intestinal Microbiota After Inulin Supplementation Halted: The Secondary Effect of Supplemented Inulin

SCOPE

Consumption of inulin could affect the intestinal microbiota composition. Hereby, it is aimed to investigate the intestinal microbial community restoration process when the inulin supplementation is terminated (i.e., the secondary effect).

METHODS AND RESULTS

The current study investigates the response and restoration of intestinal microbiota to/after high (Inulin-H) and low (Inulin-L) dosage of inulin supplementation or sequential antibiotics and inulin (Anti-Inulin-L) supplementation, based on analysis of 16S rRNA gene sequences in C57BL/6 mice. The number of significantly changed genera in response to inulin is highest in Anti-Inulin-L (n = 66) group, followed by Inulin-H (n = 51) and Inulin-L (n = 38) group. After inulin supplementation stops, microbiota of all studied groups tend to recover to their original states, with highest percentage of inulin-responding microbes stay significantly different at Anti-Inulin-L (93.94%) group, followed by Inulin-H (74.51%) and Inulin-L (44.12%) groups. Of note, the relative abundance of some non-inulin-responding taxa significantly increases during restoration.

CONCLUSION

Sequential antibiotics and inulin supplementation induce greatest changes in the intestinal microbial composition, followed by high and low dosage of inulin. Additionally, the changes induce by supplemented inulin in the intestinal microbial community, provide a chance for some microbes to outcompete the other microbes during the spontaneous restoration.

Severe fever with thrombocytopenia syndrome virus infection shapes gut microbiome of the tick vector Haemaphysalis longicornis

BACKGROUND

Ticks serve as vectors for a diverse array of pathogens, including viruses responsible for both human and livestock diseases. Symbiotic bacteria hold significant potential for controlling tick-borne disease. However, the alteration of tick gut bacterial community in response to pathogen infection has not been analyzed for any tick-borne viruses. Here, the impact of severe fever with thrombocytopenia syndrome virus (SFTSV) infection on bacterial diversity in the gut of Haemaphysalis longicornis is investigated.

METHODS

Unfed tick females were artificially infected with SFTSV. The gut samples were collected and the genomic DNA was extracted. We then investigated alterations in gut bacterial composition in response to SFTSV infection through 16S rRNA gene sequencing.

RESULTS

The study found that a reduction in the number of operational taxonomic units (OTUs) in the tick gut following SFTSV infection. However, there were no significant changes in alpha diversity indices upon infection. Four genera, including Corynebacterium, Arthrobacter, Sphingomonas, and Escherichia, were identified as biomarkers for the tick gut without SFTSV infection. Notably, the predicted correlation network indicated that the biomarkers Sphingomonas and Escherichia exhibited positive correlations within the same subcommunity, which was altered upon viral infection.

CONCLUSIONS

These findings revealed that the change in tick gut bacterial composition upon SFTSV infection and could facilitate the discovery new target for tick-borne viral disease control.

Personalizing Oncolytic Immunovirotherapy Approaches

Development of successful cancer therapeutics requires exploration of the differences in genetics, metabolism, and interactions with the immune system among malignant and normal cells. The clinical observation of spontaneous tumor regression following natural infection with microorganism has created the premise of their use as cancer therapeutics. Oncolytic viruses (OVs) originate from viruses with attenuated virulence in humans, well-characterized vaccine strains of known human pathogens, or engineered replication-deficient viral vectors. Their selectivity is based on receptor expression level and post entry restriction factors that favor replication in the tumor, while keeping the normal cells unharmed. Clinical trials have demonstrated a wide range of patient responses to virotherapy, with subgroups of patients significantly benefiting from OV administration. Tumor-specific gene signatures, including antiviral interferon-stimulated gene (ISG) expression profile, have demonstrated a strong correlation with tumor permissiveness to infection. Furthermore, the combination of OVs with immunotherapeutics, including anticancer vaccines and immune checkpoint inhibitors [ICIs, such as anti-PD-1/PD-L1 or anti-CTLA-4 and chimeric antigen receptor (CAR)-T or CAR-NK cells], could synergistically improve the therapeutic outcome. Creating response prediction algorithms represents an important step for the transition to individualized immunovirotherapy approaches in the clinic. Integrative predictors could include tumor mutational burden (TMB), inflammatory gene signature, phenotype of tumor-infiltrating lymphocytes, tumor microenvironment (TME), and immune checkpoint receptor expression on both immune and target cells. Additionally, the gut microbiota has recently been recognized as a systemic immunomodulatory factor and could further be used in the optimization of individualized immunovirotherapy algorithms.

Akkermansia muciniphila-induced trained immune phenotype increases bacterial intracellular survival and attenuates inflammation

The initial exposure to pathogens and commensals confers innate immune cells the capacity to respond distinctively upon a second stimulus. This training capacity might play key functions in developing an adequate innate immune response to the continuous exposure to bacteria. However, the mechanisms involved in induction of trained immunity by commensals remain mostly unexplored. A. muciniphila represents an attractive candidate to study the promotion of these long-term responses. Here, we show that priming of macrophages with live A. muciniphila enhances bacterial intracellular survival and decreases the release of pro- and anti-inflammatory signals, lowering the production of TNF and IL-10. Global transcriptional analysis of macrophages after a secondary exposure to the bacteria showed the transcriptional rearrangement underpinning the phenotype observed compared to acutely exposed cells, with the increased expression of genes related to phagocytic capacity and those involved in the metabolic adjustment conducing to innate immune training. Accordingly, key genes related to bacterial killing and pro-inflammatory pathways were downregulated. These data demonstrate the importance of specific bacterial members in the modulation of local long-term innate immune responses, broadening our knowledge of the association between gut microbiome commensals and trained immunity as well as the anti-inflammatory probiotic potential of A. muciniphila.

Function and therapeutic prospects of next-generation probiotic Akkermansia muciniphila in infectious diseases

Akkermansia muciniphila is a gram-negative bacterium that colonizes the human gut, making up 3-5% of the human microbiome. A. muciniphila is a promising next-generation probiotic with clinical application prospects. Emerging studies have reported various beneficial effects of A. muciniphila including anti-cancer, delaying aging, reducing inflammation, improving immune function, regulating nervous system function, whereas knowledge on its roles and mechanism in infectious disease is currently unclear. In this review, we summarized the basic characteristics, genome and phenotype diversity, the influence of A. muciniphila and its derived components on infectious diseases, such as sepsis, virus infection, enteric infection, periodontitis and foodborne pathogen induced infections. We also provided updates on mechanisms how A. muciniphila protects intestinal barrier integrity and modulate host immune response. In summary, we believe that A. muciniphila is a promising therapeutic probiotic that may be applied for the treatment of a variety of infectious diseases.

Intestinal dysbiosis exacerbates susceptibility to the anti-NMDA receptor encephalitis-like phenotype by changing blood brain barrier permeability and immune homeostasis

Changes in the intestinal microbiota have been observed in patients with anti-N-methyl-D-aspartate receptor encephalitis (NMDARE). However, whether and how the intestinal microbiota is involved in the pathogenesis of NMDARE susceptibility needs to be demonstrated. Here, we first showed that germ-free (GF) mice that underwent fecal microbiota transplantation (FMT) from NMDARE patients, whose fecal microbiota exhibited low short-chain fatty acid content, decreased abundance of Lachnospiraceae, and increased abundance of Verrucomicrobiota, Akkermansia, Parabacteroides, Oscillospirales, showed significant behavioral deficits. Then, these FMT mice were actively immunized with an amino terminal domain peptide from the GluN1 subunit (GluN1356-385) to mimic the pathogenic process of NMDARE. We found that FMT mice showed an increased susceptibility to an encephalitis-like phenotype characterized by more clinical symptoms, greater pentazole (PTZ)-induced susceptibility to seizures, and higher levels of T2 weighted image (T2WI) hyperintensities following immunization. Furthermore, mice with dysbiotic microbiota had impaired blood-brain barrier integrity and a proinflammatory condition. In NMDARE-microbiota recipient mice, the levels of Evan's blue (EB) dye extravasation increased, ZO-1 and claudin-5 expression decreased, and the levels of proinflammatory cytokines (IL-1, IL-6, IL-17, TNF-α and LPS) increased. Finally, significant brain inflammation, mainly in hippocampal and cortical regions, with modest neuroinflammation, immune cell infiltration, and reduced expression of NMDA receptors were observed in NMDARE microbiota recipient mice following immunization. Overall, our findings demonstrated that intestinal dysbiosis increased NMDARE susceptibility, suggesting a new target for limiting the occurrence of the severe phenotype of NMDARE.

Metabolic alterations in urine among the patients with severe fever with thrombocytopenia syndrome

BACKGROUND

The pathogenesis of severe fever with thrombocytopenia syndrome (SFTS) remained unclear. We aimed to profile the metabolic alterations in urine of SFTS patients and provide new evidence for its pathogenesis.

METHODS

A case-control study was conducted in the 154th hospital in China. Totally 88 cases and 22 controls aged ≥ 18 years were enrolled. The cases were selected from laboratory-confirmed SFTS patients. The controls were selected among SFTSV-negative population. Those with diabetes, cancer, hepatitis and other sexually transmitted diseases were excluded in both groups. Fatal cases and survival cases were 1:1 matched. Inter-group differential metabolites and pathways were obtained, and the inter-group discrimination ability was evaluated.

RESULTS

Tryptophan metabolism and phenylalanine metabolism were the top one important metabolism pathway in differentiating the control and case groups, and the survival and fatal groups, respectively. The significant increase of differential metabolites in tryptophan metabolism, including 5-hydroxyindoleacetate (5-HIAA), L-kynurenine (KYN), 5-hydroxy-L-tryptophan (5-HTP), 3-hydroxyanthranilic acid (3-HAA), and the increase of phenylpyruvic acid and decrease of hippuric acid in phenylalanine metabolism indicated the potential metabolic alterations in SFTSV infection. The increase of 5-HIAA, KYN, 5-HTP, phenylpyruvic acid and hippuric acid were involved in the fatal progress of SFTS patients.

CONCLUSIONS

Tryptophan metabolism and phenylalanine metabolism might be involved in the pathogenesis of SFTSV infection. These findings provided new evidence for the pathogenesis and treatment of SFTS.

Exploring gut-lung axis crosstalk in SARS-CoV-2 infection: Insights from a hACE2 mouse model

Based on the forefront of clinical research, there is a growing recognition that the gut microbiota, which plays a pivotal role in shaping both the innate and adaptive immune systems, may significantly contribute to the pathogenesis of coronavirus disease 2019 (COVID-19). Although an association between altered gut microbiota and COVID-19 pathogenesis has been established, the causative mechanisms remain incompletely understood. Additionally, the validation of the precise functional alterations within the gut microbiota relevant to COVID-19 pathogenesis has been limited by a scarcity of suitable animal experimental models. In the present investigation, we employed a newly developed humanized ACE2 knock-in (hACE2-KI) mouse model, capable of recapitulating critical aspects of pulmonary and intestinal infection, to explore the modifications in the gut microbiota following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Examination of fecal samples using 16S rRNA gene profiling unveiled a notable reduction in species richness and conspicuous alterations in microbiota composition at 6 days postinfection (dpi). These alterations were primarily characterized by a decline in beneficial bacterial species and an escalation in certain opportunistic pathogens. Moreover, our analysis entailed a correlation study between the gut microbiota and plasma cytokine concentrations, revealing the potential involvement of the Lachnospiraceae_NK4A136_group and unclassified_f_Lachnospiraceae genera in attenuating hyperinflammatory responses triggered by the infection. Furthermore, integration of gut microbiota data with RNA-seq analysis results suggested that the increased presence of Staphylococcus in fecal samples may signify the potential for bacterial coinfection in lung tissues via gut translocation. In summary, our hACE2-KI mouse model effectively recapitulated the observed alterations in the gut microbiota during SARS-CoV-2 infection. This model presents a valuable tool for elucidating gut microbiota-targeted strategies aimed at mitigating COVID-19.

Akkermansia muciniphila in infectious disease: A new target for this next-generation probiotic?

The common gastrointestinal commensal Akkermansia muciniphila is a mucin-degrading bacterium that is greatly reduced in individuals consuming a high-fat diet. Increasing evidence from a variety of clinical and pre-clinical studies suggests that oral supplementation with Akkermansia can improve metabolic health and moderate systemic inflammation. We and others have demonstrated a role for Akkermansia administration in protection against infectious disease and the outcome from sepsis. Very recent studies have indicated the molecular mechanisms by which A. muciniphila may interact with the host to influence systemic immune-regulation and control of microbial pathogenesis. Here we consider recent studies which demonstrate the efficacy of this potential next-generation probiotic in animal models of Salmonella Typhimurium, Listeria monocytogenes and Clostridioides difficile as well as influenza virus and phlebovirus. The potential mechanisms by which A. muciniphila may influence local and systemic immune responses are discussed.

Akkermansia in the gastrointestinal tract as a modifier of human health

Akkermansia sp are common members of the human gut microbiota. Multiple reports have emerged linking the abundance of A. muciniphila to health benefits and disease risk in humans and animals. This review highlights findings linking Akkermansia species in the gastrointestinal (GI) tract to health outcomes across a spectrum of disorders, encompassing those that affect the digestive, respiratory, urinary, and central nervous systems. The mechanism through which Akkermansia exerts a beneficial versus a detrimental effect on health is likely dependent on the genetic makeup of the host metabolic capacity and immunomodulatory properties of the strain, the competition or cooperation with other members of the host microbiota, as well as synergy with co-administered therapies.

Microbiota-derived acetate is associated with functionally optimal virus-specific CD8+ T cell responses to influenza virus infection via GPR43-dependent metabolic reprogramming

The microbiota-associated factors that affect host susceptibility and adaptive immunity to influenza A virus (IAV) infection have not been fully elucidated. By comparing the microbiota composition between survivors and mice that succumbed to IAV strain PR8 infection, we identified that the commensal bacterium Blautia coccoides protects antibiotics (Abx)-treated or germ-free (GF) mice from PR8 infection by inducing functionally optimal virus-specific CD8+ T cell responses. Administration of exogenous acetate reproduced the protective effect of B. coccoides monocolonization in Abx and GF mice, enhancing oxidative phosphorylation and glycolysis as well as secretion of IFN-γ and granzyme B in virus-specific CD8+ T cells, dependent on GPR43 signaling and acetyl-CoA synthetase 2. Thus, we have demonstrated that microbiota-derived acetate possesses an antiviral effect that induces an optimal virus-specific CD8+ T cell response to IAV PR8 infection via GPR43-dependent metabolic reprogramming.

Diet-driven differential response of Akkermansia muciniphila modulates pathogen susceptibility

The erosion of the colonic mucus layer by a dietary fiber-deprived gut microbiota results in heightened susceptibility to an attaching and effacing pathogen, Citrobacter rodentium. Nevertheless, the questions of whether and how specific mucolytic bacteria aid in the increased pathogen susceptibility remain unexplored. Here, we leverage a functionally characterized, 14-member synthetic human microbiota in gnotobiotic mice to deduce which bacteria and functions are responsible for the pathogen susceptibility. Using strain dropouts of mucolytic bacteria from the community, we show that Akkermansia muciniphila renders the host more vulnerable to the mucosal pathogen during fiber deprivation. However, the presence of A. muciniphila reduces pathogen load on a fiber-sufficient diet, highlighting the context-dependent beneficial effects of this mucin specialist. The enhanced pathogen susceptibility is not owing to altered host immune or pathogen responses, but is driven by a combination of increased mucus penetrability and altered activities of A. muciniphila and other community members. Our study provides novel insights into the mechanisms of how discrete functional responses of the same mucolytic bacterium either resist or enhance enteric pathogen susceptibility.

Novel tripeptide RKH derived from Akkermansia muciniphila protects against lethal sepsis

OBJECTIVE

The pathogenesis of sepsis is complex, and the sepsis-induced systemic proinflammatory phase is one of the key drivers of organ failure and consequent mortality. Akkermansia muciniphila (AKK) is recognised as a functional probiotic strain that exerts beneficial effects on the progression of many diseases; however, whether AKK participates in sepsis pathogenesis is still unclear. Here, we evaluated the potential contribution of AKK to lethal sepsis development.

DESIGN

Relative abundance of gut microbial AKK in septic patients was evaluated. Cecal ligation and puncture (CLP) surgery and lipopolysaccharide (LPS) injection were employed to establish sepsis in mice. Non-targeted and targeted metabolomics analysis were used for metabolites analysis.

RESULTS

We first found that the relative abundance of gut microbial AKK in septic patients was significantly reduced compared with that in non-septic controls. Live AKK supplementation, as well as supplementation with its culture supernatant, remarkably reduced sepsis-induced mortality in sepsis models. Metabolomics analysis and germ-free mouse validation experiments revealed that live AKK was able to generate a novel tripeptide Arg-Lys-His (RKH). RKH exerted protective effects against sepsis-induced death and organ damage. Furthermore, RKH markedly reduced sepsis-induced inflammatory cell activation and proinflammatory factor overproduction. A mechanistic study revealed that RKH could directly bind to Toll-like receptor 4 (TLR4) and block TLR4 signal transduction in immune cells. Finally, we validated the preventive effects of RKH against sepsis-induced systemic inflammation and organ damage in a piglet model.

CONCLUSION

We revealed that a novel tripeptide, RKH, derived from live AKK, may act as a novel endogenous antagonist for TLR4. RKH may serve as a novel potential therapeutic approach to combat lethal sepsis after successfully translating its efficacy into clinical practice.

Underestimated health risks: Dietary restriction magnify the intestinal barrier dysfunction and liver injury in mice induced by polystyrene microplastics

Microplastics (MPs) have gained significant attention due to their widespread presence in the environment. While studies have been conducted to investigate the risks associated with MPs, the potential effects of MPs on populations with varying dietary habits, such as dietary restriction (DR), remain largely undefined. The sensitivity of the body to invasive contaminants may increase due to insufficient food intake. Here, we aimed to investigate whether dietary restriction could affect the toxicity of MPs in mice. Following a 5-week exposure to 200 μg/L polystyrene microplastics (PSMPs), DR-PSMPs treatment group exhibited significant intestinal barrier dysfunction compared to ND-PSMPs treatment group, as determined by histopathological and biochemical analysis. Dietary restriction worsened liver oxidative stress and bile acid disorder in mice exposed to PSMPs. 16S rRNA sequencing analysis revealed that DR-PSMPs treatment caused alterations in gut microbiota composition, including the downregulation of probiotics abundance and upregulation of pathogenic bacteria abundance. The negative effects caused by PSMPs in mice with dietary restriction could attribute to increased MPs bioaccumulation, declined water intake, reduced probiotics abundance, and elevated pathogenic bacteria abundance, as well as the susceptibility of the dietary restriction individual. Our findings hint that the biological effects of contaminants could be affected by dietary habits.

Cholecystectomy Significantly Alters Gut Microbiota Homeostasis and Metabolic Profiles: A Cross-Sectional Study

Cholecystectomy (CCE) is a standard clinical treatment for conditions like gallstones and cholecystitis. However, its link to post-CCE syndrome, colorectal cancer, and nonalcoholic fatty liver disease has raised concerns. Additionally, studies have demonstrated the disruptive effects of CCE on gut microbiota homeostasis and bile acid (BA) metabolism. Considering the role of gut microbiota in regulating host metabolic and immune pathways, the use of dietary and probiotic intervention strategies to maintain a stable gut ecosystem after CCE could potentially reduce associated disease risks. Inter-study variations have made it challenging to identify consistent gut microbiota patterns after CCE, a prerequisite for targeted interventions. In this study, we first meta-analyzed 218 raw 16S rRNA gene sequencing datasets to determine consistent patterns of structural and functional changes in the gut microbiota after CCE. Our results revealed significant alterations in the gut microbiota's structure and function due to CCE. Furthermore, we identified characteristic gut microbiota changes associated with CCE by constructing a random model classifier. In the validation cohort, this classifier achieved an area under the receiver operating characteristic curve (AUC) of 0.713 and 0.683 when distinguishing between the microbiota of the CCE and healthy groups at the family and genus levels, respectively. Further, fecal metabolomics analysis demonstrated that CCE also substantially modified the metabolic profile, including decreased fecal short-chain fatty acid levels and disrupted BA metabolism. Importantly, dietary patterns, particularly excessive fat and total energy intake, influenced gut microbiota and metabolic profile changes post-CCE. These dietary habits were associated with further enrichment of the microbiota related to BA metabolism and increased levels of intestinal inflammation after CCE. In conclusion, our study identified specific alterations in gut microbiota homeostasis and metabolic profiles associated with CCE. It also revealed a potential link between dietary patterns and gut microbiota changes following CCE. Our study provides a theoretical basis for modulating gut microbiota homeostasis after CCE using long-term dietary strategies and probiotic interventions.

Cryptotanshinone alleviates radiation-induced lung fibrosis via modulation of gut microbiota and bile acid metabolism

Cryptotanshinone (CPT), a major biological active ingredient extracted from root of Salvia miltiorrhiza (Danshen), has shown several pharmacological activities. However, the effect of CPT on radiation-induced lung fibrosis (RILF) is unknown. In this study, we explored the protective effects of CPT on RILF from gut-lung axis angle, specifically focusing on the bile acid (BA)-gut microbiota axis. We found that CPT could inhibit the process of epithelial mesenchymal transformation (EMT) and suppress inflammation to reduce the deposition of extracellular matrix in lung fibrosis in mice induced by radiation. In addition, 16S rDNA gene sequencing and BAs-targeted metabolomics analysis demonstrated that CPT could improve the dysbiosis of gut microbiota and BA metabolites in RILF mice. CPT significantly enriched the proportion of the beneficial genera Enterorhabdus and Akkermansia, and depleted that of Erysipelatoclostridium, which were correlated with increased intestinal levels of several farnesoid X receptor (FXR) natural agonists, such as deoxycholic acid and lithocholic acid, activating the FXR pathway. Taken together, these results suggested that CPT can regulate radiation-induced disruption of gut microbiota and BAs metabolism of mice, and reduce the radiation-induced lung inflammation and fibrosis. Thus, CPT may be a promising drug candidate for treating RILF.

Akkermansia muciniphila: A potential target and pending issues for oncotherapy

In the wake of the development of metagenomic, metabolomic, and metatranscriptomic approaches, the intricate interactions between the host and various microbes are now being progressively understood. Numerous studies have demonstrated evident changes in gut microbiota during the process of a variety of diseases, such as diabetes, obesity, aging, and cancers. Notably, gut microbiota is viewed as a potential source of novel therapeutics. Currently, Next-generation probiotics (NGPs) are gaining popularity as therapeutic agents that alter the gut microbiota and affect cancer development. Akkermansia muciniphila (A. muciniphila), a representative commensal bacterium, has received substantial attention over the past decade as a promising NGP. The components and metabolites of A. muciniphila can directly or indirectly affect tumorigenesis, in particular through its effects on antitumor immunosurveillance, including the stimulation of pattern recognition receptors (PRRs), which also leads to better outcomes in a variety of situations, including the prevention and curation of cancers. In this article, we systematically summarize the role of A. muciniphila in tumorigenesis (involving gastrointestinal and non-gastrointestinal cancers) and in tumor therapy. In particular, we carefully discuss some critical scientific issues that need to be solved for the future using A. muciniphila as a representative beneficial bacterium in tumor treatment, which might provide bright clues and assistance for the application of drugs targeting A. muciniphila in clinical oncotherapy.

A High-Fat, High-Cholesterol Diet Promotes Intestinal Inflammation by Exacerbating Gut Microbiome Dysbiosis and Bile Acid Disorders in Cholecystectomy

Patients with post-cholecystectomy (PC) often experience adverse gastrointestinal conditions, such as PC syndrome, colorectal cancer (CRC), and non-alcoholic fatty liver disease (NAFLD), that accumulate over time. An epidemiological survey further revealed that the risk of cholecystectomy is associated with high-fat and high-cholesterol (HFHC) dietary intake. Mounting evidence suggests that cholecystectomy is associated with disrupted gut microbial homeostasis and dysregulated bile acids (BAs) metabolism. However, the effect of an HFHC diet on gastrointestinal complications after cholecystectomy has not been elucidated. Here, we aimed to investigate the effect of an HFHC diet after cholecystectomy on the gut microbiota-BA metabolic axis and elucidate the association between this alteration and the development of intestinal inflammation. In this study, a mice cholecystectomy model was established, and the levels of IL-Iβ, TNF-α, and IL-6 in the colon were increased in mice fed an HFHC diet for 6 weeks. Analysis of fecal BA metabolism showed that an HFHC diet after cholecystectomy altered the rhythm of the BA metabolism by upregulating liver CPY7A1, CYP8B1, and BSEP and ileal ASBT mRNA expression levels, resulting in increased fecal BA levels. In addition, feeding an HFHC diet after cholecystectomy caused a significant dysbiosis of the gut microbiota, which was characterized by the enrichment of the metabolic microbiota involved in BAs; the abundance of pro-inflammatory gut microbiota and related pro-inflammatory metabolite levels was also significantly higher. In contrast, the abundance of major short-chain fatty acid (SCFA)-producing bacteria significantly decreased. Overall, our study suggests that an HFHC diet after cholecystectomy promotes intestinal inflammation by exacerbating the gut microbiome and BA metabolism dysbiosis in cholecystectomy. Our study also provides useful insights into the maintenance of intestinal health after cholecystectomy through dietary or probiotic intervention strategies.

A genetic system for Akkermansia muciniphila reveals a role for mucin foraging in gut colonization and host sterol biosynthesis gene expression

Akkermansia muciniphila, a mucophilic member of the gut microbiota, protects its host against metabolic disorders. Because it is genetically intractable, the mechanisms underlying mucin metabolism, gut colonization and its impact on host physiology are not well understood. Here we developed and applied transposon mutagenesis to identify genes important for intestinal colonization and for the use of mucin. An analysis of transposon mutants indicated that de novo biosynthesis of amino acids was required for A. muciniphila growth on mucin medium and that many glycoside hydrolases are redundant. We observed that mucin degradation products accumulate in internal compartments within bacteria in a process that requires genes encoding pili and a periplasmic protein complex, which we term mucin utilization locus (MUL) genes. We determined that MUL genes were required for intestinal colonization in mice but only when competing with other microbes. In germ-free mice, MUL genes were required for A. muciniphila to repress genes important for cholesterol biosynthesis in the colon. Our genetic system for A. muciniphila provides an important tool with which to uncover molecular links between the metabolism of mucins, regulation of lipid homeostasis and potential probiotic activities.

Comparing steamed and wine-stewed Rehmanniae Radix in terms of Yin-nourishing effects via metabolomics and microbiome analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Rehmanniae Radix Praeparata (RRP), the processed root of Rehmannia glutinosa, has been widely used to treat Yin deficiency syndrome in traditional Chinese medicine. RRP is available in two forms: processed by steaming with water (SRR) or processed by stewing with yellow rice wine (WRR). Previous work has documented chemical differences in the secondary metabolomes and glycomes of SRR and WRR.

AIM OF THE STUDY

This study aimed to compare SRR and WRR in terms of Yin-nourishing effects via metabolomics and microbiome analysis.

MATERIALS AND METHODS

ICR mice were orally administered with thyroxine for 14 d to induce Yin deficiency. Changes in biochemical indices and histopathology were detected. Serum metabolomics analysis and microbial 16S rRNA sequencing were performed to compare the therapeutic effects and mechanisms between SRR and WRR in treating thyroxine-induced Yin deficiency.

RESULTS

Both SRR and WRR decreased serum T3, T4 and MDA levels, and increased SOD activity. SRR more effectively decreased serum Cr, and ameliorated kidney injury, while WRR showed better regulation on ratio of cAMP/cGMP and serum TSH, and relieved thyroid injury. Both SRR and WRR regulated tyrosine, glycerophospholipid, and linoleic acid metabolism and the citric acid cycle. Additionally, SRR regulated fatty acid metabolism, while WRR influenced alanine, aspartate and glutamate metabolism, and bile acid biosynthesis. SRR significantly enriched the genera Staphylococcus and Bifidobacterium in the gut microbiome, while WRR significantly enriched the genera Akkermansia, Bacteroides and Parabacteroides, and decreased the abundance of Lactobacillus.

CONCLUSIONS

SRR displayed better protective effects on kidney, while WRR showed stronger effects on thyroid in thyroxine-induced Yin deficient mice. These differences might be due to different regulating effects of SRR and WRR on the metabolome and gut microbiota.

The tick saliva peptide HIDfsin2 promotes the tick-borne virus SFTSV replication in vitro by enhancing p38 signal pathway

Pathogens co-evolved with ticks to facilitate blood collection and pathogen transmission. Although tick saliva was recently found to be rich in bioactive peptides, it is still elusive which saliva peptide promotes virus transmission and which pathways are invovled. Here, we used a saliva peptide HIDfsin2 and a severe fever with thrombocytopenia syndrome virus (SFTSV) both carried by the tick Haemaphysalis longicornis to elucidate the relationship between tick saliva components and tick-borne viruses. HIDfsin2 was found to promote the replication of SFTSV in a dose-dependent manner in vitro. HIDfsin2 was further revealed to MKK3/6-dependently magnify the activation of p38 MAPK. The overexpression, knockdown and phosphorylation site mutation of p38α indicated that p38 MAPK activation facilitated SFTSV infection in A549 cells. Moreover, the blockade of p38 MAPK activation significantly suppressed SFTSV replication. Differently, HIDfsin2 or pharmacological inhibition of p38 MAPK activation had no effect on a mosquito-borne Zika virus (ZIKV). All these results showed that HIDfsin2 specifically promoted SFTSV replication through the MKK3/6-dependent enhancement of p38 MAPK activation. Our study provides a new perspective on the transmission of tick-borne viruses under natural conditions, and supports that the blockade of p38 MAPK activation can be a promising strategy against the mortal tick-borne virus SFTSV.

Small molecule metabolites: discovery of biomarkers and therapeutic targets

Metabolic abnormalities lead to the dysfunction of metabolic pathways and metabolite accumulation or deficiency which is well-recognized hallmarks of diseases. Metabolite signatures that have close proximity to subject's phenotypic informative dimension, are useful for predicting diagnosis and prognosis of diseases as well as monitoring treatments. The lack of early biomarkers could lead to poor diagnosis and serious outcomes. Therefore, noninvasive diagnosis and monitoring methods with high specificity and selectivity are desperately needed. Small molecule metabolites-based metabolomics has become a specialized tool for metabolic biomarker and pathway analysis, for revealing possible mechanisms of human various diseases and deciphering therapeutic potentials. It could help identify functional biomarkers related to phenotypic variation and delineate biochemical pathways changes as early indicators of pathological dysfunction and damage prior to disease development. Recently, scientists have established a large number of metabolic profiles to reveal the underlying mechanisms and metabolic networks for therapeutic target exploration in biomedicine. This review summarized the metabolic analysis on the potential value of small-molecule candidate metabolites as biomarkers with clinical events, which may lead to better diagnosis, prognosis, drug screening and treatment. We also discuss challenges that need to be addressed to fuel the next wave of breakthroughs.