Alterations of gut microbiota contribute to the progression of unruptured intracranial aneurysms

The oral microbiota: new insight into intracranial aneurysms

BACKGROUND

Intracranial aneurysms (IAs) are a significant clinical concern, with detection rates increasing due to advances in imaging technologies. However, precise mechanisms underlying their pathophysiology remain incompletely understood. Recent evidence suggests a pivotal role of oral microbiota dysbiosis, particularly periodontal pathogens, in systemic inflammation that may contribute to IA development and rupture.

OBJECTIVE

This review aims to critically evaluate the association between oral microbiota dysbiosis and the pathogenesis of IAs, with a focus on the molecular and immunological mechanisms by which oral pathogens influence vascular pathology.

METHODS

We conducted a comprehensive analysis of the literature regarding the impact of oral microbial dysbiosis on IA pathophysiology, emphasizing the role of specific pathogenic species, such as Porphyromonas gingivalis. The review explores how these pathogens may mediate chronic inflammation through hematogenous spread, gut microbiome alterations, and neuroinflammatory processes, leading to vascular remodeling and cerebrovascular instability.

RESULTS

The findings suggest that oral microbial dysbiosis, particularly the presence of pathogenic bacteria, is implicated in the systemic inflammatory response that exacerbates the structural integrity of the cerebrovascular wall. Chronic inflammatory states induced by oral pathogens contribute to extracellular matrix degradation, impaired vascular remodeling, and an increased susceptibility to IA rupture.

CONCLUSIONS

The findings highlight the importance of maintaining oral microbiota homeostasis as a potential therapeutic target for preventing IAs. Interventions aimed at restoring oral microbial balance may represent a novel strategy for reducing the burden of IA formation and rupture, highlighting the need for an integrated approach to oral health and IAs prevention.

Gut microbiota characteristics and prognostic value in patients with aneurysmal subarachnoid hemorrhage: A clinical study

BACKGROUND

This study aims to explore the characteristics of gut microbiota in the aneurysmal subarachnoid hemorrhage (aSAH) group and the healthy control group, as well as in the good prognosis group and the poor prognosis group. It also investigates the relationship between the severity of aSAH and gut microbiota, and the predictive value of gut microbiota for the prognosis outcome of patients with aSAH.

METHODS

Stool samples from 22 patients with aSAH and 11 healthy controls were subjected to metagenomic sequencing, and species annotations were obtained through the taxonomic information database corresponding to the NR database. The characteristics of the gut microbiota in the aSAH group versus the healthy control group, and the good prognosis group versus the poor prognosis group were analyzed.The correlations between differential microbiota and clinical hematology markers between the aSAH and control groups and between gut microbiota and aSAH severity were analyzed. The prognosis of patients with aSAH after three months was assessed. Finally, gut microbiota with significant effects were screened for potential as biomarkers, and the predictive value of gut microbiota for different prognostic outcomes in patients with aSAH was explored.

RESULTS

Gut microbiota composition, diversity, and abundance differed significantly between patients in the aSAH group and the control group. Additionally, the composition, diversity, and abundance differed between patients with good and poor prognosis. Five dominant genera--Bacillus, Eggerthia, Hominisplanchenecus, Carnobacterium, and Bifidobacterium were identified as potential biomarkers for predicting aSAH outcomes.

CONCLUSION

Patients with aSAH have altered gut microbiota composition, structure, and diversity compared with the healthy population. These alterations may be potential biomarkers for aSAH diagnosis and outcome prediction.

The aspartate superpathway in gut microbiota-related metabolic pathways mediates immune cell protection against COPD and IPF: a Mendelian randomization analysis

BACKGROUND

Both genetic and environmental factors can influence idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) development. The gut microbiota plays crucial roles in maintaining tissue homeostasis. Dysregulation of the gut microbiota can result in disease. However, whether the alteration of the gut microbiota influences IPF and COPD remains unknown.

RESEARCH QUESTION

What is the causal relationship between IPF, COPD and the gut microbiota-related metabolic pathways? What are the potential intermediate mediators in this relationship?

STUDY DESIGN AND METHODS

Intersect the gut microbiota and its metabolic pathways associated with IPF and COPD. Utilizing summary data from GWAS in public databases, a two-sample Mendelian randomization (MR) analysis was conducted on the gut microbiota-related metabolic pathway, the aspartate superpathway, in relation to IPF and COPD. Furthermore, we employed a two-step MR to quantify the proportion of influence mediated by monocytes and cDCs on the aspartate superpathway in relation to IPF and COPD.

RESULTS

The MR analysis found that the aspartate superpathway decreased the risk of developing IPF and COPD. Monocytes and cDCs acted as intermediary substances, participating in this with influence proportions of 7.88% and 6.27%, respectively.

INTERPRETATION

There is a causal link between the gut microbiota-related metabolic pathway, the aspartate superpathway, and IPF and COPD, where the influence is partially mediated by monocytes and cDCs. In clinical practice, we increase the focus on gut microbiota-mediated immune cells in relation to IPF and COPD.

Exploring the Role of Gut Microbiota and Probiotics in Acute Pancreatitis: A Comprehensive Review

Acute pancreatitis (AP) is a common and potentially severe gastrointestinal condition characterized by acute inflammation of the pancreas. The pathophysiology of AP is multifactorial and intricate, involving a cascade of events that lead to pancreatic injury and systemic inflammation. The progression of AP is influenced by many factors, including genetic predispositions, environmental triggers, and immune dysregulation. Recent studies showed a critical involvement of the gut microbiota in shaping the immune response and modulating inflammatory processes during AP. This review aims to provide a comprehensive overview of the emerging role of gut microbiota and probiotics in AP. We analyzed the implication of gut microbiota in pathogenesis of AP and the modification during an acute attack. The primary goals of microbiome-based therapies, which include probiotics, prebiotics, antibiotics, fecal microbiota transplantation, and enteral nutrition, are to alter the composition of the gut microbial community and the amount of metabolites derived from the microbiota. By resetting the entire flora or supplementing it with certain beneficial organisms and their byproducts, these therapeutic approaches aim to eradicate harmful microorganisms, reducing inflammation and avoiding bacterial translocation and the potential microbiota-based therapeutic target for AP from nutrition to pre- and probiotic supplementation to fecal transplantation.

Odoribacter splanchnicus-A Next-Generation Probiotic Candidate

As an important intestinal microorganism, Odoribacter splanchnicus frequently appears in high-throughput sequencing analyses, although pure culture research on this microorganism is not as advanced. It is widely present in the mammalian gut and is closely associated with the health status of the host and the incidence of various diseases. In recent years, changes in the abundance of O. splanchnicus have been found to be positively or negatively correlated with health issues, such as obesity, metabolic syndrome, diabetes, and intestinal inflammation. It may exhibit a dual protective or promotional role in specific diseases. Thus, it may play an important role in regulating host metabolism, immune response, and intestinal homeostasis. Additional research has revealed that O. splanchnicus can synthesize various metabolites, especially short-chain fatty acids (SCFAs), which play a key role in promoting intestinal health, enhancing energy metabolism, improving insulin resistance, and regulating immune responses in the host. Therefore, O. splanchnicus is a strong candidate for "next-generation probiotics", and its potential probiotic function provides novel ideas for the development of functional foods and the prevention and treatment of metabolic and intestinal inflammatory diseases. These findings can help develop new biological treatment strategies and optimize health management plans.

Taurine levels and long-term adverse cerebrovascular risk in moyamoya disease: A prognostic perspective study

BACKGROUND

Taurine has been proven to play a significant role in cardiovascular and cerebrovascular diseases, but its relationship with moyamoya disease (MMD) remains unclear. This study aims to investigate the association between serum taurine levels and long-term adverse cerebrovascular events in patients with MMD after revascularization.

METHODS

This study involved 352 patients with MMD, from whom comprehensive clinical data and blood samples were collected. Serum taurine levels were measured using liquid chromatography-tandem mass spectrometry, and the relationship between serum taurine concentration and various blood indices was evaluated. Cerebrovascular adverse events included transient ischemic attack, ischemic stroke, and hemorrhagic stroke. Taurine, analyzed as a continuous variable, was found to predict a cut-off for postoperative cerebrovascular adverse events in MMD patients at 842.52 μmol/L. The impact of serum taurine levels on the risk of cerebrovascular events was analyzed using Kaplan-Meier (KM) curves, and univariate and multivariate Cox regression analyses were performed to identify predictive factors for postoperative prognosis.

RESULTS

Grouping MMD patients by serum taurine levels revealed that higher taurine levels were significantly associated with a lower proportion of hemorrhagic MMD (p = 0.044). Compared with ischemic MMD, patients with hemorrhagic MMD had lower taurine concentrations (p = 0.005). KM curves showed that the incidence of postoperative cerebrovascular adverse events in the high taurine group was significantly lower than in the low taurine group (p = 0.026). Univariate Cox regression analysis indicated that higher taurine concentrations significantly reduced the risk of postoperative cerebrovascular adverse events (Hazard Ratio [HR] = 0.334, 95 % Confidence Interval [CI] = 0.121-0.923, p = 0.035). Furthermore, the multivariate Cox regression model confirmed that taurine level is an independent predictor of long-term adverse cerebrovascular events, with the high concentration group showing a significantly reduced risk.

CONCLUSIONS

Low serum taurine levels are associated with a higher risk of long-term adverse cerebrovascular events following MMD revascularization. This suggests the significant potential of serum taurine as a prognostic biomarker for postoperative outcomes.

CLINICAL TRIAL REGISTRY NUMBER

URL: https://www.chictr.org.cn/. Unique identifier: ChiCTR2200061889.

Decreased Lactococcus lactis and Propionic Acid in Feces of Patients with Moyamoya Disease: Possible Implications of Immune Dysregulation

INTRODUCTION

Moyamoya disease (MMD) is a cerebrovascular disease characterized by progressive steno-occlusive lesions in the terminal portion of the internal carotid artery. Despite its unknown etiology, immune dysregulation is regarded as a critical trigger for delineating the pathophysiology of MMD. The gut microbiota produces short-chain fatty (SCFA) and organic acids, influencing immune regulation and vascular remodeling. We aimed to characterize the gut microbiota in patients with MMD.

METHODS

Sixteen patients with MMD and sixteen healthy controls (CON) were included in this study. We performed 16S rRNA sequencing of fecal samples, analyzed microbiome diversity and composition, and quantified SCFA and organic acid levels using liquid chromatography.

RESULTS

There were no significant differences in α- and β-diversities among feces from the MMD patients and CON. However, 16S rRNA sequencing identified defective Lactococcus lactis (0 ± 0 in the MMD patients vs. 0.026 ± 0.084 in healthy CON, p = 0.0181) and abundant Gordinobacter pamelaeae (0.030 ± 0.039 in the patients vs. 0.001 ± 0.005 in healthy CON, p = 0.003) are strongly linked to MMD. Propionic acid levels were significantly lower in feces of the MMD patients compared to healthy CON (0.83 ± 0.34 mg/g in the MMD patients vs. 1.20 ± 0.55 mg/g in healthy CON, p = 0.028).

CONCLUSION

Decreased L. lactis can result in reduced lactic acid and propionic acid levels in the feces of the patients. This imbalance in the gut microbiome and SCFA/organic acid levels could contribute to immune dysregulation underlying the vascular remodeling seen in MMD.

Bacterial DNA in patients with ruptured intracranial aneurysms: Investigating the potential role of periodontal and gut microbiota

BACKGROUND AND OBJECTIVES

Chronic periodontal bacterial infections and disruptions in gut microbiota are responsible for systemic inflammation, which may contribute to the rupture of intracranial aneurysm. This study aimed to assess the presence of bacterial DNA from Fusobacterium nucleatum and Escherichia coli within arterial tissues of intracranial aneurysms.

METHODOLOGY

A comprehensive cross-sectional study was conducted, applying stringent inclusion and exclusion criteria to carefully select the study population from patients admitted to the Division of Neurosurgery at Hospital das Clínicas, University of São Paulo. Samples were collected post-aneurysm microsurgical clipping, preserving their integrity for subsequent DNA extraction. Polymerase chain reaction (PCR) techniques were employed to identify bacterial DNA within these samples.

RESULTS

In total, 36 patient samples underwent a detailed analysis. The presence of Escherichia coli DNA exhibited a statistically significant correlation with the occurrence of ruptured intracranial aneurysms (Qualitative Odds Ratio [OR] 4.3 [1.01 - 23.4] and Quantitative OR 0.99 [0.99-1.0], Student's t-test [P = 0.9]). However, the presence of Fusobacterium nucleatum DNA did not demonstrate a statistically significant correlation with ruptured intracranial aneurysms (Qualitative OR 1.52 [0.4-6.1] and Quantitative OR 0.04 [0.01-5.22 ×108], Student's t-test [P = 0.78]).

CONCLUSION

The identification of Escherichia coli bacterial DNA in arterial tissues was positively associated with the occurrence of ruptured intracranial aneurysms, suggesting a potential role for these microorganisms in aneurysm pathogenesis and rupture. The development of therapeutic and prophylactic strategies can be established through future research endeavors.

Targeting gut S. aureofaciens Tü117 serves as a new potential therapeutic intervention for the prevention and treatment of hypertension

Currently, the regulation of specific gut microbial metabolism for the development and/or treatment of hypertension remains largely unexplored. Here, we show that α-lipomycin, produced by Streptomyces aureofaciens (S. aureofaciens) Tü117, is upregulated in the serum of high-salt diet (HSD) mice and patients with essential hypertension. α-lipomycin causes vasodilation impairment involving transient receptor potential vanilloid 4 (TRPV4)-mediated nitric oxide and endothelium-derived hyperpolarizing factor pathways in mice. We also find that Lactobacillus plantarum (L. plantarum) CCFM639 attenuates the increase in blood pressure (BP) potentially through inhibiting the proliferation of S. aureofaciens Tü117 in mice. An exploratory intervention trial indicates that L. plantarum CCFM639 supplementation reduces BPs in subjects newly diagnosed with pre-hypertension or stage 1 hypertension without antihypertensive medication. Our findings provide evidence for a role of S. aureofaciens Tü117-associated α-lipomycin elevation in the pathogenesis of HSD-induced hypertension, highlighting that targeting gut bacteria serves as a new therapeutic intervention for hypertension.

Animal Models of Intracranial Aneurysms: History, Advances, and Future Perspectives

Intracranial aneurysms (IA) are a disease process with potentially devastating outcomes, particularly when rupture occurs leading to subarachnoid hemorrhage. While some candidates exist, there is currently no established pharmacological prevention of growth and rupture. The development of prophylactic treatments is a critical area of research, and preclinical models using animals play a pivotal role. These models, which utilize various species and induction methods, each possess unique characteristics that can be leveraged depending on the specific aim of the study. A comprehensive understanding of these models, including their historical development, is crucial for appreciating the advantages and limitations of aneurysm research in animal models.We summarize the significant roles of animal models in IA research, with a particular focus on rats, mice, and large animals. We discuss the pros and cons of each model, providing insights into their unique characteristics and contributions to our understanding of IA. These models have been instrumental in elucidating the pathophysiology of IA and in the development of potential therapeutic strategies.A deep understanding of these models is essential for advancing research on preventive treatments for IA. By leveraging the unique strengths of each model and acknowledging their limitations, researchers can conduct more effective and targeted studies. This, in turn, can accelerate the development of novel therapeutic strategies, bringing us closer to the goal of establishing an effective prophylactic treatment for IA. This review aims to provide a comprehensive view of the current state of animal models in IA research.

Investigating the role of gut microbiota in hemorrhagic stroke: Evidence from causal analysis

BACKGROUND

Hemorrhagic stroke is potentially fatal and debilitating. Previous studies have indicated a potential correlation between gut microbiota and hemorrhagic stroke.

METHODS

We conducted a two-sample Mendelian randomization (MR) study to assess the potential causal effects of gut microbiota on hemorrhagic stroke, including nontraumatic intracranial hemorrhage (ntICH), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH). The inverse variance weighted (IVW) method was employed as the primary MR evaluation approach. Complementary methods of MR‒Egger, simple mode, weighted mode, and weighted median were utilized for validation. Heterogeneity and pleiotropy were assessed using Cochran's Q and MR‒Egger intercept tests. MR-PRESSO and leave-one-out analyses were employed to identify instrumental outliers.

RESULTS

The IVW estimates demonstrated significant causal associations between ntICH and taxa from two classes (Clostridia, Methanobacteria), one order (Methanobacteriales), two families (Clostridiales vadin BB60 group, Methanobacteriaceae), and two genera (Catenibacterium, unknown genus id. 1000000073) (P<0.05). Subgroup analyses revealed causal links between ICH and taxa from two classes (Clostridia, Methanobacteria), two orders (Methanobacteriales, Rhodospirillales), two families (Acidaminococcaceae, Methanobacteriaceae), and four genera (Butyricimonas, Catenibacterium, Lachnospiraceae UCG010, unknown genus id.2755) (P<0.05). Furthermore, for the SAH subgroup, we identified causal associations with taxa from one family (Rikenellaceae) and six genera (Alloprevotella, Enterorhabdus, Hungatella, Lachnoclostridium, Parabacteroides, Ruminococcus gauvreauii group) (P<0.05). These findings remained robust across all sensitivity tests.

CONCLUSIONS

Our findings provide support for the causal effects of specific gut microbial taxa on hemorrhagic stroke and identify promising targets for its prevention and therapy. Further research is warranted to validate these associations.

Harnessing the Power of Probiotics: Boosting Immunity and Safeguarding against Various Diseases and Infections

The human microbiome, a diverse microorganism community, crucially defends against pathogens. Probiotics, postbiotics, and paraprobiotics alone and in combination are potent in countering fungal and waterborne infections, particularly against viral threats. This review focuses on the mechanisms of the microbiome against viral infections, emphasizing probiotic interventions. Certain Lactic Acid Bacteria (LAB) strains effectively eliminate toxic aflatoxin B1 (AFB1) from microfungi-produced mycotoxins. LAB binding to AFB1 persists post-gastric digestion, and pre-incubation with mycotoxins reduces probiotic adhesion to mucus. Oral probiotic administration in animals increases mycotoxin excretion, reducing associated health risks. Bifidobacterium longum and Lactobacillus rhamnosus show exceptional efficacy in removing cyanobacterial toxin microcystin-LR from drinking water. Engineered probiotics promise advanced therapeutic applications for metabolic disorders, Alzheimer's, and type 1 diabetes, serving as diagnostic tools for detecting pathogens and inflammation markers. In antimicrobial peptide production, genetically modified probiotics producing human β-defensin 2 (HBD2) treat Crohn's disease with implemented biocontainment strategies preventing unintended environmental impacts.

Untargeted metabolomics to detect and identify plasma metabolic signatures associated with intracranial aneurysm and its rupture

The biological basis for metabolic differences between unruptured and ruptured intracranial aneurysm (UIA and RIA) populations and their potential role in triggering IA rupture remain unclear. The aim of this study was to analyze the plasma metabolic profiles of patients with UIA and RIA using an untargeted metabolomic approach and to develop a model for early rupture classification. Plasma samples were analyzed using an ultra-high-performance liquid chromatography high-resolution tandem mass spectrometry-based platform. Least absolute shrinkage and selection operator regression and random forest machine learning methods were employed for metabolite feature selection and predictive model construction. Among 49 differential plasma metabolites identified, 31 were increased and 18 were decreased in the plasma of RIA patients. Five key metabolites-canrenone, piperine, 1-methyladenosine, betaine, and trigonelline-were identified as having strong potential to discriminate between UIA and RIA patients. This combination of metabolites demonstrated high diagnostic accuracy, with an area under the curve exceeding 0.95 in both the training and validation datasets. Our finding highlights the significance of plasma metabolites as potential biomarkers for early detection of IA rupture risk, offering new insights for clinical practice and future research on IA management.

Multiple omics reveal link between the microbiota-gut-brain axis and intracranial aneurysm rupture

Intracranial aneurysms (IAs) are benign cerebrovascular maladies characterized by wall dilatation in the intracranial arteries. Nevertheless, spontaneous aneurysmal rupture can cause a life-threatening spontaneous subarachnoid hemorrhage (SAH). Emerging evidence indicates potential associations between gut dysbiosis and IAs pathogenesis, though the relationship with IA rupture remains unclear. This research analyzed 124 fecal samples for microbiomics and 160 for metabolomics, with the discovery and validation sets established for cross-validation. We identified differential gut microbiota and metabolites associated with ruptured intracranial aneurysms (RIAs) and developed a superior risk assessment model. Subsequent integrative analyses and validation revealed a significant link between disrupted unsaturated fatty acid and essential amino acid metabolic pathways and IA rupture, driven by alterations in gut microbiota. This study underscores the potential association between the gut-brain axis and IA rupture, while also highlighting gut microbiota dysbiosis as a potential risk factor for IA rupture and providing biomarkers for assessment.

Modification of Intestinal Flora Can Improve Host Metabolism and Alleviate the Damage Caused by Chronic Hypoxia

Prolonged exposure to hypoxic conditions can lead to reduced appetite, stunted growth, systemic inflammation, and pulmonary hypertension. Previous studies have indicated a correlation between gut dysbiosis and the development of hypoxia-related hazards. We designed an experiment to investigate the effect of microbiota on mitigating hypoxic damage. Gut microbiota from high-altitude-adapted species (Ochotona curzoniae) were transplanted into Sprague Dawley (SD) rats, which were then housed in a simulated 6000 m altitude environment for 30 days. After the experiment, we conducted analyses on average daily weight gain (ADG), feed conversion ratio (FCR), mean pulmonary artery pressure (mPAP), gut flora, and fecal metabolism. The results demonstrated that the ADG in the transplantation group (2.98 ± 0.17 g) was significantly higher than in the control groups (2.68 ± 0.19 g and 2.26 ± 0.13 g) (p < 0.05). The FCR was reduced in the transplantation group (6.30 ± 0.33 g) compared to the control groups (8.20 ± 1.15 g and 8.83 ± 0.45 g) (p < 0.05). The mPAP was decreased in the transplantation group (38.1 ± 1.13 mmHg) compared to the control groups (43.4 ± 1.30 mmHg and 43.5 ± 1.22 mmHg) (p < 0.05). Multi-omics analysis revealed that Lachnospiraceae, Desulfovibrionaceae, and specific amino acid metabolic pathways play crucial roles in hypoxia and are associated with both inflammation and nutritional metabolism. This study proposes a novel approach to the treatment of hypoxic pulmonary hypertension and holds potential significance for improving high-altitude developmental potential.

The gut microbiome and serum metabolome are altered and interrelated in patients with intracranial atherosclerotic stenosis

OBJECTIVES

To evaluate the relationship among the gut microbiome, serum metabolites and the Intracranial atherosclerosis stenosis.

MATERIALS AND METHODS

Integrated analysis of 16S rDNA sequencing of fecal samples and untargeted serum metabolomics was applied to identify alterations in the gut microbiome and serum metabolome in 29 Intracranial atherosclerosis stenosis patients and 29 healthy control individuals.

RESULTS

Compared to healthy control individuals, the abundances of forty-five genera and one hundred seventy-seven metabolites were significantly altered in Intracranial atherosclerosis stenosis patients. At the species level, the Intracranial atherosclerosis stenosis group exhibited higher abundances of Bacteroidetes and lower abundances of Megaphaera and Muribacoccaceae. Microbial functional prediction analysis revealed enhanced activity of bacterial chemotaxis and oxidative phosphorylation within the Intracranial atherosclerosis stenosis group. In terms of metabolomic findings, the levels of dulcitol were significantly increased in the Intracranial atherosclerosis stenosis group. The levels of specific metabolites within the phosphatidylcholine and lysophosphatidylcholine families, such as PC (14:0e/24:4) and LPC 20:5, were increased, while the levels of certain other specific metabolites were decreased. Dysregulation of certain pathways, such as unsaturated fatty acid metabolism, arginine and proline metabolism may be involved in the development of Intracranial atherosclerosis stenosis. Correlation analysis of the gut microbiome and metabolites revealed a positive correlation between Bacteroides and multiple metabolites, such as Acar 12:3 and PC (8:0/22:6).

CONCLUSIONS

Our analysis revealed that Bacteroides is a key bacterial genus in gut dysbiosis and may be related to the development of Intracranial atherosclerosis stenosis.

Evidence for a Role of Gut Microbiota and Probiotics in Aneurysmal Pathogenesis and Possible Therapeutics: A Systematic Review of the Literature

INTRODUCTION

Several studies investigated the implication of the gut microbiota (GM) in the formation and progression of aneurysms, suggesting a key role for GM metabolites in aneurysmal pathogenesis and prognosis.

AIM

This systematic review aims to collect key findings concerning the impact of gut bacterial compositions, GM-related metabolites, probiotics administration, and inflammatory markers in aneurysmal development and rupture.

METHODS

A PubMed, Medline, Embase, and Web of Science database search was conducted in accordance with PRISMA guidelines for systematic reviews, targeting all studies assessing the GM's role in aneurysms till 2023.

RESULTS

Data from 19 out of 292 non-duplicated studies were included. Based on the published literature, aneurysmal incidents in several locations were accompanied by an alteration in specific intestinal bacteria that may affect the prognosis of the aneurysm. The gut dysbiosis was also accompanied by modifications in the metabolic pathways. Hence, the administration of specific probiotics showed a significant implication in reversing the GM-related changes that were affecting the aneurysm, leading to a decrease in its severity, a better prognosis, and even serving as a prophylactic approach.

CONCLUSIONS

The outcomes of this review highlight the role of GM in the pathogenesis of aneurysms, assessing some involved mechanistic pathways such as gut dysbiosis, inflammation, and the alteration of gut-derived metabolites levels, which orient new research on developing therapeutic strategies.

The value of systemic immune inflammation index, white blood cell to platelet ratio, and homocysteine in predicting the instability of small saccular intracranial aneurysms

Inflammation has a destructive effect on the homeostasis of the vascular wall, which is involved in the formation, growth, and rupture of human intracranial aneurysms (IAs) disease progression. However, inflammation-related markers have not been well studied in the risk stratification of unruptured IAs. The purpose of this study was to investigate the predictive value of serum inflammatory markers in the unstable progression of small saccular intracranial aneurysms (SIAs). This study retrospectively included 275 patients with small SIAs (aneurysm diameter less than or equal to 7 mm), to compare the level difference of serum inflammatory complex marker systemic immune-inflammatory index (SII), white blood cell to platelet ratio (WPR), and homocysteine (Hcy) in patients with stable (asymptomatic unruptured) and unstable (symptomatic unruptured, ruptured) small SIAs. 187 patients (68%) had aneurysm-related compression symptoms and rupture outcomes. In the multivariate logistic regression after adjusting for baseline differences, SII, WPR, and Hcy were independent risk factors for the instability of small SIAs, the prediction model combined with other risk factors (previous stroke history, aneurysm irregularity) showed good predictive ability for the instability of small SIAs, with an area under the curve of 0.905. In addition, correlation analysis showed that SII, WPR, and Hcy also had significant differences in patients with symptomatic unruptured and ruptured small SIAs, and higher inflammation levels often promoted the disease progression of small SIAs. Higher levels of SII, WPR and Hcy can be used as independent predictors of instability of small SIAs. As an economical and convenient biomarker, it is crucial for clinical treatment strategies of stable small SIAs.

Integrated metagenomic and metabolomic analysis reveals distinctive stage-specific gut-microbiome-derived metabolites in intracranial aneurysms

OBJECTIVE

Our study aimed to explore the influence of gut microbiota and their metabolites on intracranial aneurysms (IA) progression and pinpoint-related metabolic biomarkers derived from the gut microbiome.

DESIGN

We recruited 358 patients with unruptured IA (UIA) and 161 with ruptured IA (RIA) from two distinct geographical regions for conducting an integrated analysis of plasma metabolomics and faecal metagenomics. Machine learning algorithms were employed to develop a classifier model, subsequently validated in an independent cohort. Mouse models of IA were established to verify the potential role of the specific metabolite identified.

RESULTS

Distinct shifts in taxonomic and functional profiles of gut microbiota and their related metabolites were observed in different IA stages. Notably, tryptophan metabolites, particularly indoxyl sulfate (IS), were significantly higher in plasma of RIA. Meanwhile, upregulated tryptophanase expression and indole-producing microbiota were observed in gut microbiome of RIA. A model harnessing gut-microbiome-derived tryptophan metabolites demonstrated remarkable efficacy in distinguishing RIA from UIA patients in the validation cohort (AUC=0.97). Gut microbiota depletion by antibiotics decreased plasma IS concentration, reduced IA formation and rupture in mice, and downregulated matrix metalloproteinase-9 expression in aneurysmal walls with elastin degradation reduction. Supplement of IS reversed the effect of gut microbiota depletion.

CONCLUSION

Our investigation highlights the potential of gut-microbiome-derived tryptophan metabolites as biomarkers for distinguishing RIA from UIA patients. The findings suggest a novel pathogenic role for gut-microbiome-derived IS in elastin degradation in the IA wall leading to the rupture of IA.

Colorectal cancer-specific microbiome in peripheral circulation and cancer tissues

Introduction

Accumulating evidence has supported that gut microbiota and metabolite profiles play indispensable roles in the pathogenesis of colorectal cancer (CRC), which ranks as the third most common cancer and the second leading cause of cancer-related deaths worldwide. However, alterations in tumoral or circulating microbiomes in CRC remain incompletely understood. It has been well-documented that tissue or serum microbiomes with low microbial biomass could be screened by use of 2bRAD sequencing for microbiome (2bRAD-M) at the species resolution.

Methods

In order to validate the microbial biomarkers distinguishing CRC and the variations in microorganisms present in serum and tumors, we performed 2bRAD-M to characterize the microbiomes in serum and cancer tissues of CRC patients with and without lymph node or liver metastasis.

Results

The composition of dominated microbiota in serum was different from that of tissue samples, while the microbial community composition of tumors was similar to that of the tumor-adjacent tissues. The analysis of α-diversity and β-diversity has revealed notable variations in serum microbiota diversities in CRC patients, particularly those with liver metastasis. Multiple CRC-specific microbial species, such as Moraxella A cinereus, Flavobacterium sp001800905, and Acinetobacter albensis, were identified in serum. Complicated functions and KEGG pathways were also confirmed in CRC according to the metastasis status.

Discussion

This study has found significant alterations in the microbial compositions and diversities in CRC and CRC-specific microbial species in both circulation and cancer tissues, which may serve as promising biomarkers for the screening, diagnosis and prognosis prediction of CRC. In particular, CRC-specific bacterial taxa are promising markers, holding transformative potentials in establishing personalized screening and risk stratification, refining much earlier non-invasive diagnostic approaches, and enhancing diagnostic sensitivity.

Oral bacterial genic expression detection in aneurysm wall of a French population sample - preliminary monocentric study

INTRODUCTION

The etiology of brain aneurysms remains poorly understood. Finnish research suggests that oral bacteria might contribute to the development and rupture of brain aneurysms. Previous studies by our team have not confirmed these findings, likely due to methodological differences. We aimed to replicate the Finnish study with a French population, using the same primers and comparing the results to internal controls.

METHODS

We used RT-qPCR to retrospectively analyze the expression of oral bacterial genes in eight patients. During surgical procedures, four tissue types were consistently sampled from each patient: the aneurysmal wall, the superficial temporal artery (STA), the middle meningeal artery (MMA), and the dura mater (DM). Results were expressed as fold differences employing the 2-∆∆Ct method, and statistical analyses were performed accordingly.

RESULTS

Our cohort included eight patients, evenly split into ruptured and unruptured groups. The sex distribution was balanced (4 females, 4 males). We observed DNA expression from oral bacteria in all sampled tissues; however, there were no significant differences between the ruptured and unruptured groups.

CONCLUSION

We detected oral bacterial gene expression in the aneurysmal wall, STA, MMA, and DM in a sample of French patients. Although limited by the small sample size, our results suggest a potential role for bacterial involvement in vascular invasiveness related to bacteremia. These findings do not definitively link oral bacteria to the pathogenesis of aneurysm development and rupture.

Hydroxytyrosol Alleviates Intestinal Oxidative Stress by Regulating Bile Acid Metabolism in a Piglet Model

Infants and young animals often suffer from intestinal damage caused by oxidative stress, which may adversely affect their overall health. Hydroxytyrosol, a plant polyphenol, has shown potential in decreasing intestinal oxidative stress, but its application and mechanism of action in infants and young animals are still inadequately documented. This study selected piglets as a model to investigate the alleviating effects of hydroxytyrosol on intestinal oxidative stress induced by diquat and its potential mechanism. Hydroxytyrosol improved intestinal morphology, characterized by higher villus height and villus height/crypt depth. Meanwhile, hydroxytyrosol led to higher expression of Occludin, MUC2, Nrf2, and its downstream genes, and lower expression of cytokines IL-1β, IL-6, and TNF-α. Both oxidative stress and hydroxytyrosol resulted in a higher abundance of Clostridium_sensu_stricto_1, and a lower abundance of Lactobacillus and Streptococcus, without a significant effect on short-chain fatty acids levels. Oxidative stress also led to disorders in bile acid (BA) metabolism, such as the lower levels of primary BAs, hyocholic acid, hyodeoxycholic acid, and tauroursodeoxycholic acid, which were partially restored by hydroxytyrosol. Correlation analysis revealed a positive correlation between these BA levels and the expression of Nrf2 and its downstream genes. Collectively, hydroxytyrosol may reduce oxidative stress-induced intestinal damage by regulating BA metabolism.

Aspirin treatment for unruptured intracranial aneurysms: Focusing on its anti-inflammatory role

Intracranial aneurysms (IAs), as a common cerebrovascular disease, claims a worldwide morbidity rate of 3.2%. Inflammation, pivotal in the pathogenesis of IAs, influences their formation, growth, and rupture. This review investigates aspirin's modulation of inflammatory pathways within this context. With IAs carrying significant morbidity and mortality upon IAs rupture and current interventions limited to surgical clipping and endovascular coiling, the quest for pharmacological options is imperative. Aspirin's role in cardiovascular prevention, due to its anti-inflammatory effects, presents a potential therapeutic avenue for IAs. In this review, we examine aspirin's efficacy in experimental models and clinical settings, highlighting its impact on the progression and rupture risks of unruptured IAs. The underlying mechanisms of aspirin's impact on IAs are explored, with its ability examined to attenuate endothelial dysfunction and vascular injury. This review may provide a theoretical basis for the use of aspirin, suggesting a promising strategy for IAs management. However, the optimal dosing, safety, and long-term efficacy remain to be established. The implications of aspirin therapy are significant in light of current surgical and endovascular treatments. Further research is encouraged to refine aspirin's clinical application in the management of unruptured IAs, with the ultimate aim of reducing the incidence of aneurysms rupture.

Longitudinal multi-omics analysis uncovers the altered landscape of gut microbiota and plasma metabolome in response to high altitude

BACKGROUND

Gut microbiota is significantly influenced by altitude. However, the dynamics of gut microbiota in relation to altitude remains undisclosed.

METHODS

In this study, we investigated the microbiome profile of 610 healthy young men from three different places in China, grouped by altitude, duration of residence, and ethnicity. We conducted widely targeted metabolomic profiling and clinical testing to explore metabolic characteristics.

RESULTS

Our findings revealed that as the Han individuals migrated from low altitude to high latitude, the gut microbiota gradually converged towards that of the Tibetan populations but reversed upon returning to lower altitude. Across different cohorts, we identified 51 species specifically enriched during acclimatization and 57 species enriched during deacclimatization to high altitude. Notably, Prevotella copri was found to be the most enriched taxon in both Tibetan and Han populations after ascending to high altitude. Furthermore, significant variations in host plasma metabolome and clinical indices at high altitude could be largely explained by changes in gut microbiota composition. Similar to Tibetans, 41 plasma metabolites, such as lactic acid, sphingosine-1-phosphate, taurine, and inositol, were significantly elevated in Han populations after ascending to high altitude. Germ-free animal experiments demonstrated that certain species, such as Escherichia coli and Klebsiella pneumoniae, which exhibited altitude-dependent variations in human populations, might play crucial roles in host purine metabolism.

CONCLUSIONS

This study provides insights into the dynamics of gut microbiota and host plasma metabolome with respect to altitude changes, indicating that their dynamics may have implications for host health at high altitude and contribute to host adaptation. Video Abstract.

Hungatella hathewayi bacteremia due to acute appendicitis: A case report and a narrative review

Hungatella species, including Hungatella hathewayi and Hungatella effluvii, previously identified as part of the Clostridium genus, are anaerobic bacteria primarily residing in the gut microbiome, with infrequent implications in human infections. This article presents the case of an 87-year-old Asian male admitted for a hyperosmolar hyperglycemic state with septic shock secondary to Hungatella hathewayi bacteremia originating from acute appendicitis. Remarkably, the bacterium was detected in the blood 48 hours before the emergence of clinical and radiographic evidence of acute appendicitis. Additionally, we conducted a literature review to identify all documented human infections caused by Hungatella species. Timely microbial identification in such cases is essential for implementing targeted antibiotic therapy and optimizing clinical outcomes.

Fecal calprotectin is a novel biomarker to predict the clinical outcomes of patients with ruptured intracranial aneurysm

BACKGROUND

Intracranial aneurysm (IA) is a common cerebrovascular disease and the leading cause of spontaneous subarachnoid hemorrhage. Recent evidence suggests that gut microbiota is involved in the pathophysiological process of IA through the gut-brain axis. However, the role of gut inflammation in the development of IA has yet to be clarified. Our study aimed to investigate whether fecal calprotectin (FC) level, a sensitive marker of gut inflammation, is correlated with the development of IA and the prognosis of patients with ruptured IA (RIA).

METHODS

182 patients were collected from January 2022 to January 2023, including 151 patients with IA and 31 healthy individuals. 151 IA patients included 109 patients with unruptured IA (UIA) and 42 patients with RIA. The FC level was measured by enzyme-linked immunosorbent assay. Other detailed information was obtained from an electronic medical record system.

RESULTS

Compared with healthy controls, the FC levels in patients with IA were increased (P < 0.0001). Patients with RIA had significantly higher FC levels than UIA patients (P < 0.0001). Moreover, the FC level in RIA patients with unfavorable outcomes was higher than in RIA patients with favorable outcomes. Logistic regression analysis showed that the elevated FC level was an independent risk factor for a 3-month poor prognosis in patients with RIA (OR=1.005, 95% CI = 1.000 -1.009, P = 0.044).

CONCLUSION

Fecal calprotectin level is significantly elevated in IA patients, especially those with RIA. FC is a novel biomarker of 3-month poor outcomes in RIA patients.

Bioinspired Fluorine Labeling for 19F NMR-Based Plasma Amine Profiling

Metabolite profiling serves as a powerful tool that advances our understanding of biological systems, disease mechanisms, and environmental interactions. In this study, we present an approach employing 19F-nuclear magnetic resonance (19F NMR) spectroscopy for plasma amine profiling. This method utilizes a highly efficient and reliable fluorine-labeling reagent, 3,5-difluorosalicylaldehyde, which effectively emulates pyridoxal phosphate, facilitating the formation of Schiff base compounds with primary amines. The fluorine labeling allows for distinct resolution of 19F NMR signals from amine mixtures, leading to precise identification and quantification of amine metabolites in human plasma. This advancement offers valuable tools for furthering metabolomics research.

Gut Microbiota, Metabolites, Circulating Cytokines and Growth Factors, Plasma Proteins, and Risk of Intracranial Aneurysms: A Two‐Sample Mendelian Randomization Study

Background: Increasing evidence implicates the gut microbiota, metabolites, circulating cytokines and growth factors, and plasma proteins as potential susceptibility factors for intracranial aneurysm (IA). However, due to their complexity, the causal relationship between these factors and IA remains unclear. Our goal was to determine whether these factors are causally associated with IA, UIA, and SAH and provide suggestions for the prevention and treatment of these cerebrovascular diseases.

Methods: Utilizing data from genome‐wide association studies (GWAS), we conducted a large‐scale Mendelian randomization (MR) analysis between these factors and diseases using five different models (Wald ratio, IVW, MR‐Egger, weighted median, and MRPRESSO). Several sensitivity analyses were also applied to ensure the robustness of the results.

Results: Our MR analysis revealed several significant causal relationships between 18 gut microbiota taxa (genus.Bilophila‐SAH, beta[95%CI] = −1.08[−1.61 ~ −0.54]), 55 blood metabolites (7‐alpha‐hydroxy‐3‐oxo‐4‐cholestenoate‐IA, beta[95%CI] = −2.78[−4.47 ~ −1.08]), 2 cytokines (IL‐6‐UIA, beta[95%CI] = 0.73[0.34 ~ 1.39]), 45 plasma proteins (RELT‐UIA, beta[95%CI] = −0.8[−1.22 ~ −0.38]), and IA, UIA, and SAH. Many of these were reported for the first time.

Conclusions: In conclusion, our study provides reference of the potential causal effects of gut microbiota, blood metabolites, cytokines, and plasma proteins on IA, UIA, and SAH. These findings may contribute to a better understanding of the pathogenesis and potential therapeutic targets for these cerebrovascular diseases.

Integrated analysis of gut metabolome, microbiome, and brain function reveal the role of gut-brain axis in longevity

The role of microbiota-gut-brain axis in modulating longevity remains undetermined. Here, we performed a multiomics analysis of gut metagenomics, gut metabolomics, and brain functional near-infrared spectroscopy (fNIRS) in a cohort of 164 participants, including 83 nonagenarians (NAs) and 81 non-nonagenarians (NNAs) matched with their spouses and offspring. We found that 438 metabolites were significantly different between the two groups; among them, neuroactive compounds and anti-inflammatory substances were enriched in NAs. In addition, increased levels of neuroactive metabolites in NAs were significantly associated with NA-enriched species that had three corresponding biosynthetic potentials: Enterocloster asparagiformis, Hungatella hathewayi and Oxalobacter formigenes. Further analysis showed that the altered gut microbes and metabolites were linked to the enhanced brain connectivity in NAs, including the left dorsolateral prefrontal cortex (DLPFC)-left premotor cortex (PMC), left DLPFC-right primary motor area (M1), and right inferior frontal gyrus (IFG)-right M1. Finally, we found that neuroactive metabolites, altered microbe and enhanced brain connectivity contributed to the cognitive preservation in NAs. Our findings provide a comprehensive understanding of the microbiota-gut-brain axis in a long-lived population and insights into the establishment of a microbiome and metabolite homeostasis that can benefit human longevity and cognition by enhancing functional brain connectivity.

The Role of Gut and Oral Microbiota in the Formation and Rupture of Intracranial Aneurysms: A Literature Review

In recent years, there has been a growing interest in the role of the microbiome in cardiovascular and cerebrovascular diseases. Emerging research highlights the potential role of the microbiome in intracranial aneurysm (IA) formation and rupture, particularly in relation to inflammation. In this review, we aim to explore the existing literature regarding the influence of the gut and oral microbiome on IA formation and rupture. In the first section, we provide background information, elucidating the connection between inflammation and aneurysm formation and presenting potential mechanisms of gut-brain interaction. Additionally, we explain the methods for microbiome analysis. The second section reviews existing studies that investigate the relationship between the gut and oral microbiome and IAs. We conclude with a prospective overview, highlighting the extent to which the microbiome is already therapeutically utilized in other fields. Furthermore, we address the challenges associated with the context of IAs that still need to be overcome.

PitNETs and the gut microbiota: potential connections, future directions

The role of the gut microbiome has been widely discussed in numerous works of literature. The biggest concern is the association of the gut microbiome with the central nervous system through the microbiome-brain-gut axis in the past ten years. As more and more research has been done on the relationship between the disease of the central nervous system and gut microbes. This fact is being revealed that gut microbes seem to play an important role from the onset and progression of the disease to clinical symptoms, and new treatments. As a special tumor of the central nervous system, pituitary neuroendocrine tumors (PitNETs)are closely related to metabolism, endocrinology, and immunity. These factors are the vectors through which intestinal microbes interact with the central nervous system. However, little is known about the effects of gut microbes on the PitNET. In this review, the relationship of gut microbiota in PitNETs is introduced, the potential effects of the gut-brain axis in this relationship are analyzed, and future research directions are presented.

Hungatella hathewayi impairs the sensitivity of colorectal cancer cells to 5-FU through decreasing CDX2 expression

Hungatella hathewayi (H. hathewayi), also known as Clostridium hathewayi, has been reported to be accumulated in the colorectal cancer (CRC) samples. In addition, evidence has demonstrated that inoculation with H. hathewayi promotes the proliferation of colonic epithelial cells in mice. Herein, we explored H. hathewayi role in regulating the 5-fluorouracil (5-FU) resistance in CRC cells, and investigated the underlying mechanisms. H. hathewayi abundance in CRC tissues and the corresponding adjacent normal tissues was tested using qRT-PCR. Both parental and 5-FU resistance CRC cell lines were used to assess H. hathewayi role in regulating the 5-FU resistance of CRC cells using CCK-8, flow cytometry and animal experiments. H. hathewayi abundance was significantly increased in CRC tissues, and the high level of H. hathewayi was linked to lower overall survival rate. H. hathewayi treatment significantly weakened 5-FU effects on inhibiting cell growth and inducing cell apoptosis in CRC HCT116 and HT29 cells. In addition, H. hathewayi enhanced the 5-FU resistance of HCT116/5-FU and HT29/5-FU cells (the 5-FU resistance cell lines). In mechanism, H. hathewayi decreased the expression of CDX2, and increased the expression of nuclear accumulation of β-catenin. Overexpression of CDX2 abolished H. hathewayi-mediated enhancement in cell growth and inhibition in cell apoptosis in HCT116/5-FU and HT29/5-FU cells, as well as inhibited the expression and nuclear accumulation of β-catenin. In conclusion, H. hathewayi abundance was increased in CRC tissues, and the high level of H. hathewayi was linked to lower overall survival rate. In mechanisam, H. hathewayi treatment enhanced the 5-FU resistance of CRC cells through modulating CDX2/β-catenin signaling.

Potential application of peripheral blood biomarkers in intracranial aneurysms

Intracranial aneurysm (IA) counts are increasing yearly, with a high mortality and disability after rupture. Current diagnosis and treatment rely on costly equipment, lacking effective indicators for progression prediction and specific drugs for treatment. Recently, peripheral blood biomarkers, as common clinical test samples, reflecting the immune and inflammatory state of the body in real-time, have shown promise in providing additional information for risk stratification and treatment in IA patients, which may improve their outcomes after aneurysm rupture through anti-inflammatory therapy. Therefore, this paper reviewed the progress of potential biomarkers of IAs, including inflammatory blood indicators, cytokines, and blood lipids, aiming to aid individual management and therapy of aneurysms in clinical practices.

Gut microbiome in intracranial aneurysm growth, subarachnoid hemorrhage, and cerebral vasospasm: a systematic review with a narrative synthesis

Intracranial aneurysms (IA) are the most common cerebral vascular pathologies. Their rupture leads to the most dangerous subtype of stroke-aneurysmal subarachnoid hemorrhage (aSAH), which may be followed by cerebral vasospasm and ischemic sequelae. Recently, an imbalance within the intestinal microbiota, referred to as dysbiosis, was suggested to play a role in the formation, progression, and rupture of IA. As no systematic review on this topic exists, considering the significance of this matter and a lack of effective prophylaxis against IA or cerebral vasospasm, we aim to sum up the current knowledge regarding their associations with intestinal microbiome, identify the gaps, and determine future prospects. Scientific databases were systematically and independently searched by two authors from inception to 1st May 2023 for original articles regarding the role of intestinal microbiota in intracranial aneurysmal growth, aSAH occurrence, as well as in cerebral vasospasm following aSAH. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) checklist was followed in an abstraction process. The STROBE tool was applied to assess the risk of bias. This research was funded by the National Science Centre, Poland (grant number 2021/41/N/NZ2/00844). Of 302 records, four studies were included that fully met eligibility criteria. Studies reported (1) that the relative abundance of Hungatella hathewayi is a protective factor against aneurysm growth and rupture, resulting from the reduced inflammation and extracellular matrix remodeling in the cerebral arterial wall and from reduced metalloproteinase-mediated degradation of smooth muscle cells in cerebral vessels. (2) Relative abundance of Campylobacter ureolyticus is associated with aSAH. (3) No article has evaluated microbiota in relation to cerebral vasospasm following aSAH although there is an ongoing study. We concluded that intestinal microbiota might be a potential target for diagnostic and therapeutic tools to improve the management of cerebral aneurysms. However, more studies of prospective design are needed.

Gut microbiota in adults with moyamoya disease: characteristics and biomarker identification

Background and purpose

When it comes to the onset of moyamoya disease (MMD), environmental variables are crucial. Furthermore, there is confusion about the relationship between the gut microbiome, an environmental variable, and MMD. Consequently, to identify the particular bacteria that cause MMD, we examined the gut microbiome of MMD individuals and healthy controls (HC).

Methods

A prospective case-control investigation was performed from June 2021 to May 2022. The fecal samples of patients with MMD and HC were obtained. Typically, 16S rRNA sequencing was employed to examine their gut microbiota. The QIIME and R softwares were used to examine the data. The linear discriminant analysis effect size analysis was used to determine biomarkers. Multivariate analysis by linear models (MaAsLin)2 were used to find associations between microbiome data and clinical variables. Model performance was assessed using the receiver operating characteristic curve and the decision curve analysis.

Results

This investigation involved a total of 60 MMD patients and 60 HC. The MMD group's Shannon and Chao 1 indices were substantially lower than those of the HC cohort. β-diversity was significantly different in the weighted UniFrac distances. At the phylum level, the relative abundance of Fusobacteriota/Actinobacteria was significantly higher/lower in the MMD group than that in the HC group. By MaAsLin2 analysis, the relative abundance of the 2 genera, Lachnoclostridium and Fusobacterium, increased in the MMD group, while the relative abundance of the 2 genera, Bifidobacterium and Enterobacter decreased in the MMD group. A predictive model was constructed by using these 4 genera. The area under the receiver operating characteristic curve was 0.921. The decision curve analysis indicated that the model had usefulness in clinical practice.

Conclusions

The gut microbiota was altered in individuals with MMD, and was characterized by increased abundance of Lachnoclostridium and Fusobacterium and decreased abundance of Bifidobacterium and Enterobacter. These 4 genera could be used as biomarkers and predictors in clinical practice.

Gut microbiota and microbiota-derived metabolites in cardiovascular diseases

Cardiovascular diseases, including heart failure, coronary artery disease, atherosclerosis, aneurysm, thrombosis, and hypertension, are a great economic burden and threat to human health and are the major cause of death worldwide. Recently, researchers have begun to appreciate the role of microbial ecosystems within the human body in contributing to metabolic and cardiovascular disorders. Accumulating evidence has demonstrated that the gut microbiota is closely associated with the occurrence and development of cardiovascular diseases. The gut microbiota functions as an endocrine organ that secretes bioactive metabolites that participate in the maintenance of cardiovascular homeostasis, and their dysfunction can directly influence the progression of cardiovascular disease. This review summarizes the current literature demonstrating the role of the gut microbiota in the development of cardiovascular diseases. We also highlight the mechanism by which well-documented gut microbiota-derived metabolites, especially trimethylamine N-oxide, short-chain fatty acids, and phenylacetylglutamine, promote or inhibit the pathogenesis of cardiovascular diseases. We also discuss the therapeutic potential of altering the gut microbiota and microbiota-derived metabolites to improve or prevent cardiovascular diseases.

Gut microbiota aggravates neutrophil extracellular traps-induced pancreatic injury in hypertriglyceridemic pancreatitis

Hypertriglyceridemic pancreatitis (HTGP) is featured by higher incidence of complications and poor clinical outcomes. Gut microbiota dysbiosis is associated with pancreatic injury in HTGP and the mechanism remains unclear. Here, we observe lower diversity of gut microbiota and absence of beneficial bacteria in HTGP patients. In a fecal microbiota transplantation mouse model, the colonization of gut microbiota from HTGP patients recruits neutrophils and increases neutrophil extracellular traps (NETs) formation that exacerbates pancreatic injury and systemic inflammation. We find that decreased abundance of Bacteroides uniformis in gut microbiota impairs taurine production and increases IL-17 release in colon that triggers NETs formation. Moreover, Bacteroides uniformis or taurine inhibits the activation of NF-κB and IL-17 signaling pathways in neutrophils which harness NETs and alleviate pancreatic injury. Our findings establish roles of endogenous Bacteroides uniformis-derived metabolic and inflammatory products on suppressing NETs release, which provides potential insights of ameliorating HTGP through gut microbiota modulation.

Genetic Causal Association Between the Gut Microbiome and Intracranial Aneurysm and Subarachnoid Hemorrhage: A Two-Sample Mendelian Randomization Study

INTRODUCTION

The causal association between the gut microbiome and the risk of intracranial aneurysm (IA), subarachnoid hemorrhage (SAH), and unruptured aneurysm (uIA) is unclear.

METHODS

The single nucleotide polymorphisms concerning gut microbiome were retrieved from the gene-wide association study (GWAS) of the MiBioGen consortium. The summary-level datasets of IA and SAH were obtained from the GWAS meta-analysis of the International Stroke Genetics Consortium (ISGC). Inverse variance weighting (IVW) was utilized as the primary method, complemented with sensitivity analyses for pleiotropy and increasing robustness.

RESULTS

Five, seven, and six bacterial traits were found to have a causal effect on IA, SAH, and uIA, respectively (IVW, all P < 0.05). Family.Porphyromonadaceae and genus.Bilophila were common protective bacterial features for both SAH and uIA. The heterogeneity and pleiotropy analyses confirmed the robustness of IVW results.

CONCLUSION

Our study demonstrates that gut microbiomes may exert therapeutic effects on IA, uIA, and SAH, providing clinical implications for the development of novel biomarkers and therapeutic targets.

Identifying pyroptosis- and inflammation-related genes in intracranial aneurysms based on bioinformatics analysis

BACKGROUND

Intracranial aneurysm (IA) is the most common cerebrovascular disease, and subarachnoid hemorrhage caused by its rupture can seriously impede nerve function. Pyroptosis is an inflammatory mode of cell death whose underlying mechanisms involving the occurrence and rupture of IAs remain unclear. In this study, using bioinformatics analysis, we identified the potential pyroptosis-related genes (PRGs) and performed their inflammatory response mechanisms in IAs.

METHODS

The mRNA expression matrix of the IA tissue was obtained from the Gene Expression Omnibus database, and 51 PRGs were obtained from previous articles collected from PubMed. The differentially expressed PRGs (DEPRGs) were performed using R software. Subsequently, we performed enrichment analysis, constructed a protein-protein interaction network, performed weighted gene coexpression network analysis (WGCNA) and external validation using another dataset, and identified a correlation between hub genes and immune cell infiltration. Finally, the expression and tissue distribution of these hub genes in IA tissues were detected using Western blotting and immunohistochemical (IHC) staining.

RESULTS

In total, 12 DEPRGs associated with IA were identified in our analysis, which included 11 up-regulated and one down-regulated genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that the DEPRGs were mostly enriched in the NOD-like receptor signaling pathway, interleukin-1 beta production, and the inflammasome complex. Three hub genes, NLRP3, IL1B and IL18, were identified using Cytoscape software and the WGCNA correlation module, and external validation revealed statistically significant differences between the expression of these hub genes in the ruptured and unruptured aneurysm groups (p < 0.05). Furthermore, all AUC values were > 0.75. Immune cell infiltration analysis suggested that the hub genes are related to CD8 T cell, macrophages and mast cells. Finally, IHC staining revealed that the protein levels of these hub genes were higher in ruptured and unruptured IA tissues than in normal tissues (p < 0.05).

CONCLUSION

The results of bioinformatics analysis showed that pyroptosis is closely related to the formation and rupture of IA, and identified three potential hub genes involved in the pyroptosis and infiltration ofcells. Our findings may improve the understanding of the mechanisms underlying pyroptosis in IA.

Gut microbiota and cerebrovascular diseases: a Mendelian randomization study

Background

The causal relationship between gut microbiota and cerebrovascular disease remains unknown, despite several recent studies reporting an association between the two.

Methods

To assess this relationship, we conducted a two-sample Mendelian randomization (MR) using summary statistics data from published genome-wide association studies (GWAS). This analysis allowed us to identify bacterial taxa that may affect cerebrovascular disease. Furthermore, we performed reverse MR to further analyze the significant bacterial taxa. Finally, we conducted a two-step MR analysis to examine the mediating role of metabolic factors [systolic blood pressure (SBP), type 2 diabetes (T2D), and body mass index (BMI)] in the association between gut microbiota and cerebrovascular disease. Additionally, a series of sensitivity analyses were carried out to validate the robustness of our findings.

Results

Our results showed that a genetically predicted high abundance of family Porphyromonadaceae reduced the risk of intracranial aneurysms (IA). Moreover, using inverse variance weighted (IVW) estimates, we found a nominal causal relationship between seventeen gut microbiota and IA, as well as its subtypes. In the case of stroke and its subtypes, we observed a nominal causal relationship with thirteen, eleven, eleven, nine, and eight bacteria for AS, AIS, CES, LAS, and SVS, respectively. Reverse MR analysis showed no significant causal relationship between intracranial aneurysms and gut microbiota. However, we did find that genetically predicted any stroke (AS) and any ischemic stroke (AIS) reduced the abundance of family Clostridiaceae1 (OR: 0.74, 95% CI: 0.62-0.87, p = 3.39 × 10-4, and OR: 0.75, 95% CI: 0.66-0.87, p = 7.06 × 10-5, respectively). Furthermore, genetic prediction of AIS (OR: 0.87, 95% CI: 0.77-0.99, p = 3.05 × 10-2) was associated with a reduced abundance of the order Clostridiales. Moreover, genus Streptococcus exhibited effects on AS, AIS, and SVS which were mediated by T2D. Conversely, the association between genus Eubacterium brachy group and AIS was mediated by SBP. No significant heterogeneity of instrumental variables or horizontal pleiotropy was observed.

Conclusion

This MR analysis indicates that there exists a beneficial or detrimental causal effect of gut microbiota composition on cerebrovascular disease. And SBP and T2D may play mediating role in this process.

A Future Blood Test to Detect Cerebral Aneurysms

Intracranial aneurysms are reported to affect 2-5% of the population. Despite advances in the surgical management of this disease, diagnostic technologies have marginally improved and still rely on expensive or invasive imaging procedures. Currently, there is no blood-based test to detect cerebral aneurysm formation or quantify the risk of rupture. The aim of this review is to summarize current literature on the mechanism of aneurysm formation, specifically studies relating to inflammation, and provide a rationale and commentary on a hypothetical future blood-based test. Efforts should be focused on clinical-translational approaches to create an assay to screen for cerebral aneurysm presence and risk-stratify patients to allow for superior treatment timing and management. Cerebral Aneurysm Blood Test Considerations: There are multiple caveats to development of a putative blood test to detect cerebral aneurysm presence.

Association of gut microbiome with risk of intracranial aneurysm: a mendelian randomization study

OBJECTIVE

To investigate the potential causal link between genetic variants associated with gut microbiome and risk of intracranial aneurysm (IA) using two-sample mendelian randomization (MR).

METHODS

We performed two sets of MR analyses. At first, we selected the genome-wide statistical significant(P < 5 × 10^-8) single nucleotide polymorphisms (SNPs) as instrumental variables (IVs). Then, we selected the locus-wide significant (P < 1 × 10^-5) SNPs as IVs for the other set of analyses to obtain more comprehensive conclusions. Gut microbiome genetic association estimates were derived from a genome-wide association study (GWAS) of 18,473 individuals. Summary-level statistics for IA were obtained from 79,429 individuals, which included 7,495 cases and 71,934 controls.

RESULTS

On the basis of locus-wide significance level, inverse variance weighted(IVW) showed that Clostridia [(odds ratio (OR): 2.60; 95% confidence interval (CI): 1.00-6.72, P = 0.049)], Adlercreutzia (OR: 1.81; 95% CI: 1.10-2.99, P = 0.021) and Victivallis (OR: 1.38; 95% CI: 1.01-1.88, P = 0.044) were positively related with the risk of unruptured intracranial aneurysm(UIA); Weighted median results of MR showed Oscillospira (OR: 0.37; 95% CI: 0.17-0.84, P = 0.018) was negatively with the risk of UIA and Sutterella (OR: 1.84; 95% CI: 1.04-3.23, P = 0.035) was positively related with the risk of UIA; MR-Egger method analysis indicated that Paraprevotella (OR: 0.32; 95% CI: 0.13-0.80, P = 0.035) was negatively with the risk of UIA and Rhodospirillaceae (OR: 13.39; 95% CI: 1.44-124.47, P = 0.048) was positively related with the risk of UIA. The results suggest that Streptococcus (OR: 5.19; 95% CI: 1.25-21.56; P = 0.024) and Peptostreptococcaceae (OR: 4.92; 95% CI: 1.32-18.32; P = 0.018) may increase the risk of UIA according to genome-wide statistical significance thresholds.

CONCLUSION

This MR analysis indicates that there exists a beneficial or detrimental causal effect of gut microbiota composition on IAs.

Disordered gut microbiota promotes atrial fibrillation by aggravated conduction disturbance and unbalanced linoleic acid/SIRT1 signaling

Emerging evidence suggests an association of dysbiotic gut microbiota (GM) with atrial fibrillation (AF). The current study aimed to determine whether aberrant GM promotes AF development. A fecal microbiota transplantation (FMT) mouse model demonstrated that dysbiotic GM is sufficient to enhance AF susceptibility assessed by transesophageal burst pacing. Compared with recipients transplanted with GM obtained from healthy subjects (FMT-CH), the prolonged P wave duration and an enlarging tendency for the left atrium were detected in recipients transplanted with AF GM (FMT-AF). Meanwhile, the disrupted localizations of connexin 43 and N-cadherin and increased expression levels of phospho-CaMKII and phospho-RyR2, were observed in the atrium of FMT-AF, which indicated aggravated electrical remodeling caused by the altered gut flora. Specifically, exacerbated fibrosis disarray, collagen deposition, α-SMA expression, and inflammation in the atrium were also confirmed to be transmissible by the GM. Furthermore, deteriorated intestinal epithelial barrier and intestinal permeability, accompanied by disturbing metabolomic features in both feces and plasma, especially decreased linoleic acid (LA), were identified in FMT-AF mice. Subsequently, the anti-inflammatory role of LA among the imbalanced SIRT1 signaling discovered in the atrium of FMT-AF was confirmed in mouse HL-1 cells treated with LPS/nigericin, LA, and SIRT1 knockdown. This study provides preliminary insights into the causal role of aberrant GM in the pathophysiology of AF, suggesting the GM-intestinal barrier-atrium axis might participate in the vulnerable substrates for AF development, and the GM could be utilized as an environmental target in AF management.

Vascular smooth muscle cells in intracranial aneurysms

Intracranial aneurysm (IA) is a severe cerebrovascular disease characterized by abnormal bulging of cerebral vessels that may rupture and cause a stroke. The expansion of the aneurysm accompanies by the remodeling of vascular matrix. It is well-known that vascular remodeling is a process of synthesis and degradation of extracellular matrix (ECM), which is highly dependent on the phenotype of vascular smooth muscle cells (VSMCs). The phenotypic switching of VSMC is considered to be bidirectional, including the physiological contractile phenotype and alternative synthetic phenotype in response to injury. There is increasing evidence indicating that VSMCs have the ability to switch to various phenotypes, including pro-inflammatory, macrophagic, osteogenic, foamy and mesenchymal phenotypes. Although the mechanisms of VSMC phenotype switching are still being explored, it is becoming clear that phenotype switching of VSMCs plays an essential role in IA formation, progression, and rupture. This review summarized the various phenotypes and functions of VSMCs associated with IA pathology. The possible influencing factors and potential molecular mechanisms of the VSMC phenotype switching were further discussed. Understanding how phenotype switching of VSMC contributed to the pathogenesis of unruptured IAs can bring new preventative and therapeutic strategies for IA.

The role of the gut microbiome and its metabolites in cerebrovascular diseases

The gut microbiome is critically involved in maintaining normal physiological function in the host. Recent studies have revealed that alterations in the gut microbiome contribute to the development and progression of cerebrovascular disease via the microbiota-gut-brain axis (MGBA). As a broad communication network in the human body, MGBA has been demonstrated to have significant interactions with various factors, such as brain structure and function, nervous system diseases, etc. It is also believed that the species and composition of gut microbiota and its metabolites are intrinsically linked to vascular inflammation and immune responses. In fact, in fecal microbiota transplantation (FMT) research, specific gut microbiota and downstream-related metabolites have been proven to not only participate in various physiological processes of human body, but also affect the occurrence and development of cerebrovascular diseases directly or indirectly through systemic inflammatory immune response. Due to the high mortality and disability rate of cerebrovascular diseases, new treatments to improve intestinal dysbacteriosis have gradually attracted widespread attention to better ameliorate the poor prognosis of cerebrovascular diseases in a non-invasive way. This review summarizes the latest advances in the gut microbiome and cerebrovascular disease research and reveals the profound impact of gut microbiota dysbiosis and its metabolites on cerebrovascular diseases. At the same time, we elucidated molecular mechanisms whereby gut microbial metabolites regulate the expression of specific interleukins in inflammatory immune responses. Moreover, we further discuss the feasibility of novel therapeutic strategies targeting the gut microbiota to improve the outcome of patients with cerebrovascular diseases. Finally, we provide new insights for standardized diagnosis and treatment of cerebrovascular diseases.

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.

Diagnosis of Unruptured Intracranial Aneurysm by High-Performance Serum Metabolic Fingerprints

Unruptured intracranial aneurysm (UIA) is a high-risk cerebrovascular saccular dilatation, the effective medical management of which depends on high-performance diagnosis. However, most UIAs are diagnosed incidentally during neurovascular imaging modalities, which are time-consuming and harmful (e.g., radiation). Serum metabolic fingerprints is a promising alternative for early diagnosis of UIA. Here, nanoparticle enhanced laser desorption/ionization mass spectrometry is applied to obtain high-performance UIA-specific serum metabolic fingerprints. Diagnostic performance with an area-under-the-curve (AUC) of 0.842 (95% confidence interval (CI): 0.783-0.891) is achieved by the constructed machine learning (ML) model, including ML algorithm selection and feature selection. Lactate, glutamine, homoarginine, and 3-methylglutaconic acid are identified as the metabolic biomarker panel, which showed satisfactory diagnosis (AUC of 0.812, 95% CI: 0.727-0.897) and effective growth risk assessment (p<0.05, two-tailed t-test) of UIAs. This work aims to promote the diagnostics of UIAs and metabolic biomarker screening for medical management.

Changed cecal microbiota involved in growth depression of broiler chickens induced by immune stress

A previous study identified genes and metabolites associated with amino acid metabolism, glycerophospholipid metabolism, and inflammatory response in the liver of broilers with immune stress. The present research was designed to investigate the effect of immune stress on the cecal microbiome in broilers. In addition, the correlation between altered microbiota and liver gene expression, the correlation between altered microbiota and serum metabolites were compared using the Spearman correlation coefficients. Eighty broiler chicks were randomly assigned to 2 groups with 4 replicate pens per group and 10 birds per pen. The model broilers were intraperitoneally injected of 250 µg/kg LPS at 12, 14, 33, and 35 d of age to induce immunological stress. Cecal contents were taken after the experiment and kept at -80°C for 16S rDNA gene sequencing. Then the Pearson's correlation between gut microbiome and liver transcriptome, between gut microbiome and serum metabolites were calculated using R software. The results showed that immune stress significantly changed microbiota composition at different taxonomic levels. KEGG pathways analysis suggested that these gut microbiota were mainly involved in biosynthesis of ansamycins, glycan degradation, D-glutamine and D-glutamate metabolism, valine, leucine, and isoleucine biosynthesis and biosynthesis of vancomycin group antibiotics. Moreover, immune stress increased the activities of metabolism of cofactors and vitamins, as well as decreased the ability of energy metabolism and digestive system. Pearson's correlation analysis identified several bacteria were positively correlated with the gene expression while a few of bacteria were negatively correlated with the gene expression. The results identified potential microbiota involvement in growth depression mediated by immune stress and provided strategies such as supplement of probiotic for alleviating immune stress in broiler chickens.

Paraburkholderia sabiae administration alters zebrafish anxiety-like behavior via gut microbial taurine metabolism

Interventions to the gut microbiome manipulate the gut-brain axis and could be useful in the treatment of anxiety and depression. In this study, we demonstrated that administration of the bacterium Paraburkholderia sabiae reduces anxiety-like behavior in adult zebrafish. P. sabiae administration increased the diversity of the zebrafish gut microbiome. Linear discriminant analysis Effect Size (LEfSe) analysis revealed that the populations of Actinomycetales including Nocardiaceae, Nocardia, Gordoniaceae, Gordonia, Nakamurellaceae, and Aeromonadaceae were reduced, whereas those of Rhizobiales including Xanthobacteraceae, Bradyrhizobiaceae, Rhodospirillaceae, and Pirellulaceae were increased in the gut microbiome. Functional analysis using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2) predicted that P. sabiae administration altered taurine metabolism in the zebrafish gut, and we demonstrated that P. sabiae administration increased the taurine concentration in the brain. Since taurine functions as an antidepressant neurotransmitter in vertebrates, our results suggest that P. sabiae could improve anxiety-like behavior in zebrafish via the gut-brain axis.

Plasma metabolic signatures for intracranial aneurysm and its rupture identified by pseudotargeted metabolomics

BACKGROUND AND AIMS

The vital metabolic signatures for IA risk stratification and its potential biological underpinnings remain elusive. Our study aimed to develop an early diagnosis model and rupture classification model by analyzing plasma metabolic profiles of IA patients.

MATERIALS AND METHODS

Plasma samples from a cohort of 105 participants, including 75 IA patients in unruptured and ruptured status (UIA, RIA) and 30 control participants were collected for comprehensive metabolic evaluation using ultra-high-performance liquid chromatography-mass spectrometry-based pseudotargeted metabolomics method. Furthermore, an integrated machine learning strategy based on LASSO, random forest and logistic regression were used for feature selection and model construction.

RESULTS

The metabolic profiling disturbed significantly in UIA and RIA patients. Notably, adenosine content was significantly downregulated in UIA, and various glycine-conjugated secondary bile acids were decreased in RIA patients. Enriched KEGG pathways included glutathione metabolism and bile acid metabolism. Two sets of biomarker panels were defined to discriminate IA and its rupture with the area under receiver operating characteristic curve of 0.843 and 0.929 on the validation sets, respectively.

CONCLUSIONS

The present study could contribute to a better understanding of IA etiopathogenesis and facilitate discovery of new therapeutic targets. The metabolite panels may serve as potential non-invasive diagnostic and risk stratification tool for IA.