Gut microbiota composition reflects disease progression, severity and outcome, and dysfunctional immune responses in patients with hypertensive intracerebral hemorrhage

The Effect of Probiotics on the Prognostication of the Neutrophil-to-Lymphocyte Ratio in Severe Multi-Trauma Patients

BACKGROUND

The ratio of neutrophils to lymphocytes [NLR] is one of the most accepted prognostic indices and demonstrates a positive correlation with the severity of a disease. Given that probiotics exerted immunomodulatory properties and thus positively affected lymphocytopenia induction in severely ill patients, we performed a post hoc analysis in the ProVAP protocol to investigate whether probiotics affected the prognostication of NLR in respect to ventilator-associated pneumonia in multi-trauma patients. This cohort mandatorily involved severe traumatic brain injury patients.

METHODS

The white blood cell data of all patients, after being retrieved for the days 0 and 7, were statistically assessed in respect to neutrophils, lymphocytes and NLR among the 4 sub-groups of the study: placebo/no-VAP, placebo/VAP, probiotics/no-VAP, and probiotics/VAP.

RESULTS

Lymphopenia was dominant in placebo sub-groups, while an increased level of lymphocytes was prominent in probiotics sub-groups. This resulted in an increase [p = 0.018] in the NLR value in the probiotics/VAP group in relation to the probiotics/no-VAP cohort; this was an increase of half the value of the placebo/VAP [p < 0.001], while the NLR value in placebo/no-VAP group increased almost four-fold in relation to probiotics/no-VAP [p < 0.001]. Additionally, the ROC curve for probiotic-treated patients revealed a NLR7 cut-off value of 7.20 as a prognostic factor of VAP (AUC: 78.6%, p = 0.015, 95% CI: 62.6-94.5%), having a high specificity of 90.2% and a sensitivity of 42.9%.

CONCLUSIONS

NLR may considered a credible prognostic biomarker in multi-trauma patients since it can evaluate the immunomodulatory benefits of probiotic treatment. However, the results of the present post hoc analysis should be interpreted meticulously until further evaluation, since they may be basically species- or strain-specific.

The role of short-chain fatty acids in central nervous system diseases: A bibliometric and visualized analysis with future directions

Background

Short-chain fatty acids (SCFAs) are thought to play a key role in the microbe-gut-brain axis and involve in the pathogenesis of a variety of neurological diseases. This study aimed to identify research hotspots and evolution trends in SCFAs in central nervous diseases (CNS) and examine current research trends.

Methods

The bibliometric analysis was performed using CiteSpace, and the results were visualized via network maps.

Results

From 2002 to 2022, 480 publications in the database met the criteria. On the country level, China produced the highest number of publications, while the United States had the highest centrality. On the institutional level, University College Cork contributed to the most publications, and John F. Cryan from this university was the key researcher with considerable academic influence. The article, the role of short-chain fatty acids in microbiota-gut-brain, written by Boushra Dalile et al., in 2019 was the most cited article. Furthermore, the journal Nutrients had the maximum number of publications, while Plos One was the most cited journal. "Gut microbiome", "SCFAs", and "central nervous system" were the three most frequent keywords. Among them, SCFAs had the highest centrality. "Animal model" was the keyword with the highest burst strength, with the latest burst keywords being "social behavior", "pathogenesis", and "insulin sensitive". In addition, the research topics on SCFAs in CNS diseases from 2002 to 2022 mainly focused on following aspects: SCFAs plays a key role in microbe-gut-brain crosstalk; The classification and definition of SCFAs in the field of CNS; Several CNS diseases that are closely related to SCFAs research; Mechanism and translational studies of SCFAs in the CNS diseases. And the hotspots over the past 5 years have gradually increased the attention to the therapeutic potential of SCFAs in the CNS diseases.

Conclusion

The research of SCFAs in CNS diseases is attracting growing attention. However, there is a lack of cooperation between countries and institutions, and additional measures are required to promote cooperation. The current evidence for an association between SCFAs and CNS diseases is preliminary and more work is needed to pinpoint the precise mechanism. Moreover, large-scale clinical trials are needed in the future to define the therapeutic potential of SCFAs in CNS diseases.

The Causality between Gut Microbiota and Hypertension and Hypertension-related Complications: A Bidirectional Two-Sample Mendelian Randomization Analysis

BACKGROUND

Recent studies have highlighted a connection between gut microbiota and hypertension, yet the precise nature of this relationship remains unclear.

OBJECTIVE

This research aims to analyze the causal link between gut microbiota and hypertension, along with associated complications, utilizing two-sample bidirectional Mendelian randomization (MR).

MATERIALS AND METHODS

Summary data from genome-wide association studies (GWAS) meta-analyses, including gut microbiota GWAS data from 24 cohorts, and the latest GWAS data for hypertension-related conditions were acquired. Employing various MR methods, including Inverse-variance weighted (IVW), MR-Egger, Weighted Median, Simple Mode, and Weighted Mode, we investigated the association between gut microbiota and hypertension-related conditions. Sensitivity analyses were conducted for result stability, and reverse MR analysis assessed the potential for reverse causality.

RESULTS

The Mendelian randomization analysis involving 199 microbial taxa and four phenotypes identified 46 microbial taxa with potential causal links to hypertension and its complications. Following Bonferroni correction, genus.Victivallis showed a robust causal relationship with hypertension (OR = 1.08, 95% CI = 1.04-1.12, P = 9.82e-5). This suggests an 8% increased risk of hypertension with each unit rise in genus.Victivallis abundance.

CONCLUSION

In conclusion, this study establishes a causal connection between gut microbiota and hypertension, along with common associated complications. The findings unveil potential targets and evidence for future hypertension and complication treatment through gut microbiota interventions, offering a novel avenue for therapeutic exploration.

Mechanisms and Clinical Implications of Human Gut Microbiota-Drug Interactions in the Precision Medicine Era

The human gut microbiota, comprising trillions of microorganisms residing in the gastrointestinal tract, has emerged as a pivotal player in modulating various aspects of human health and disease. Recent research has shed light on the intricate relationship between the gut microbiota and pharmaceuticals, uncovering profound implications for drug metabolism, efficacy, and safety. This review depicted the landscape of molecular mechanisms and clinical implications of dynamic human gut Microbiota-Drug Interactions (MDI), with an emphasis on the impact of MDI on drug responses and individual variations. This review also discussed the therapeutic potential of modulating the gut microbiota or harnessing its metabolic capabilities to optimize clinical treatments and advance personalized medicine, as well as the challenges and future directions in this emerging field.

Genetically predicted causality between gut microbiota, blood metabolites, and intracerebral hemorrhage: a bidirectional Mendelian randomization study

Background

Recent research linked changes in the gut microbiota and serum metabolite concentrations to intracerebral hemorrhage (ICH). However, the potential causal relationship remained unclear. Therefore, the current study aims to estimate the effects of genetically predicted causality between gut microbiota, serum metabolites, and ICH.

Methods

Summary data from genome-wide association studies (GWAS) of gut microbiota, serum metabolites, and ICH were obtained separately. Gut microbiota GWAS (N = 18,340) were acquired from the MiBioGen study, serum metabolites GWAS (N = 7,824) from the TwinsUK and KORA studies, and GWAS summary-level data for ICH from the FinnGen R9 (ICH, 3,749 cases; 339,914 controls). A two-sample Mendelian randomization (MR) study was conducted to explore the causal effects between gut microbiota, serum metabolites, and ICH. The random-effects inverse variance-weighted (IVW) MR analyses were performed as the primary results, together with a series of sensitivity analyses to assess the robustness of the results. Besides, a reverse MR was conducted to evaluate the possibility of reverse causation. To validate the relevant findings, we further selected data from the UK Biobank for analysis.

Results

MR analysis results revealed a nominal association (p < 0.05) between 17 gut microbial taxa, 31 serum metabolites, and ICH. Among gut microbiota, the higher level of genus Eubacterium xylanophilum (odds ratio (OR): 1.327, 95% confidence interval (CI):1.154-1.526; Bonferroni-corrected p = 7.28 × 10-5) retained a strong causal relationship with a higher risk of ICH after the Bonferroni corrected test. Concurrently, the genus Senegalimassilia (OR: 0.843, 95% CI: 0.778-0.915; Bonferroni-corrected p = 4.10 × 10-5) was associated with lower ICH risk. Moreover, after Bonferroni correction, only two serum metabolites remained out of the initial 31 serum metabolites. One of the serum metabolites, Isovalerate (OR: 7.130, 95% CI: 2.648-19.199; Bonferroni-corrected p = 1.01 × 10-4) showed a very strong causal relationship with a higher risk of ICH, whereas the other metabolite was unidentified and excluded from further analysis. Various sensitivity analyses yielded similar results, with no heterogeneity or directional pleiotropy observed.

Conclusion

This two-sample MR study revealed the significant influence of gut microbiota and serum metabolites on the risk of ICH. The specific bacterial taxa and metabolites engaged in ICH development were identified. Further research is required in the future to delve deeper into the mechanisms behind these findings.

Gut microbiota as predictors of the occurrence of high on-treatment platelet reactivity in acute ischemic stroke patients

Introduction

In this study, we aimed to investigate the association between gut microbiota and high on-treatment platelet reactivity (HTPR) in patients with acute ischemic stroke (AIS).

Methods

We enrolled a total of 48 AIS patients, including 19 HTPR patients and 29 non-high on-treatment platelet reactivity (NHTPR) patients, along with 10 healthy controls. Clinical and laboratory data, as well as stool samples, were collected from all participants. The composition and function of gut microbiota were assessed using 16S rRNA sequencing. Differences in the gut microbiota between the two groups were analyzed, and a diagnostic model based on the gut microbiota was established using random forest model.

Results

HTPR patients exhibited a decreased microbial richness compared to NHTPR patients. Additionally, the relative abundance of unidentified_Clostridia and Ralstonia was lower in HTPR patients. Significant differences in biological functions, such as toxoplasmosis, were observed between the two groups. The combination of Ralstonia, unidentified-Clostridia, Mailhella, Anaerofustis, and Aggregatibacter showed excellent predictive ability for HTPR occurrence (AUC=0.896). When comparing AIS patients with healthy controls, alterations in the microbiota structure were observed in AIS patients, with imbalances in short-chain fatty acid-producing bacteria and pathogenic bacteria. Significant differences in biological functions, such as oxidative phosphorylation, were noted between the two groups. The combination of Alloprevotella, Terrisporobacter, Streptococcus, Proteus, and unidentified_Bacteria exhibited strong predictive power for AIS occurrence (AUC=0.994).

Conclusions

This study is the first to uncover the microbial characteristics of HTPR in AIS patients and demonstrate the predictive potential of specific bacterial combinations for HTPR occurrence.

The causal effects between gut microbiota and hemorrhagic stroke: a bidirectional two-sample Mendelian randomization study

Background

Recent studies have suggested that the composition of gut microbiota (GM) may change after intracerebral hemorrhage. However, the causal inference of GM and hemorrhagic stroke is unknown. Mendelian Randomization (MR) is an effective research method that removes confounding factors and investigates the causal relationship between exposure and outcome. This study intends to explore the causal relationship between GM and hemorrhagic stroke with the help of MR.

Methods

Univariable and multivariable MR analyses were performed using summary statistics of the GM (n = 18,340) in the MiBioGen consortium vs. the FinnGen consortium R9 summary statistics (intracerebral hemorrhage, subarachnoid hemorrhage, and nontraumatic intracranial hemorrhage). Causal associations between gut microbiota and hemorrhagic stroke were analyzed using inverse variance weighted, MR-Egger regression, weighted median, weighted mode, simple mode, and MR-PRESSO. Cochran's Q statistic, MR-Egger regression, and leave-one-out analysis were used to test for multiplicity and heterogeneity of instrumental variables. Separate reverse MR analyses were performed for microbiota found to be causally associated with hemorrhagic stroke in the forward MR analysis. Also, multivariate MR analyses were conducted after incorporating common confounders.

Results

Based on the results of univariable and multivariate MR analyses, Actinobacteria (phylum) (OR, 0.80; 95%CI, 0.66-0.97; p = 0.025) had a protective effect against hemorrhagic stroke, while Rikenellaceae RC9 gut group (genus) (OR, 0.81; 95%CI, 0.67-0.99; p = 0.039) had a potential protective effect. Furthermore, Dorea (genus) (OR, 1.77; 95%CI, 1.27-2.46; p = 0.001), Eisenbergiella (genus) (OR, 1.24; 95%CI, 1.05-1.48; p = 0.013) and Lachnospiraceae UCG008 (genus) (OR, 1.28; 95%CI, 1.01-1.62; p = 0.041) acted as potential risk factors for hemorrhagic stroke. The abundance of Dorea (genus) (β, 0.05; 95%CI, 0.002 ~ 0.101; p = 0.041) may increase, and that of Eisenbergiella (genus) (β, -0.072; 95%CI, -0.137 ~ -0.007; p = 0.030) decreased after hemorrhagic stroke according to the results of reverse MR analysis. No significant pleiotropy or heterogeneity was detected in any of the MR analyses.

Conclusion

There is a significant causal relationship between GM and hemorrhagic stroke. The prevention, monitoring, and treatment of hemorrhagic stroke through GM represent a promising avenue and contribute to a deeper understanding of the mechanisms underlying hemorrhagic stroke.

Gastrointestinal Dysbiosis in Neuro-Critically Ill Patients: A Systematic Review of Case-Control Studies

The human gastrointestinal tract (GIT) has a rich and pre-programmed microbiome. This microbiome is essential for physiological functions such as digestion, immunity, metabolism, and structural integrity, and of prime concern to us in conducting this study is the nervous system communication. This two-way communication between the GIT and central nervous system (CNS) is known as the gut-brain axis (GBA) and has implications for neurocritical disease. A change in any factor relating to this microbiome is known as gut dysbiosis; this can lead to aberrant communication through the GBA and in turn, can contribute to disease states. The primary objective of this study is to determine the cause-specific dysbiotic organisms in neuro-critically ill patients and their effects. We performed this study by searching published literature as per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies that defined gastrointestinal dysbiosis in neuro-critically ill patients were retrieved using Boolean search from 2000 to 2023 via PubMed and Google Scholar and narrowed the results down to five prospective case-control studies. We performed their quality assessment. The results concluded that in neurocritical illnesses such as encephalitis, brain tumors, intracerebral hemorrhage, and ischemic stroke, fluctuations in specific microbiota correlated with disease severity and prognosis. Moreover, the inhabiting population of dysbiotic organisms in neuro-critically ill patients were different in different diseases and there were no similarities in the composition of gut microbiota in these diseases. Taking stroke patients as an example; increased Enterobacteriaceae and lower Lachnospiraceae microbiome levels were found in patients with a higher stroke dysbiosis index (SDI). Those patients who developed stroke-associated pneumonia (SAP) displayed higher levels of Enterococcus species. In conclusion, dysbiosis has a major effect on neuro-critically ill patients' disease states and dysbiotic organisms can be used as a biomarker for disease. Further prospective studies on this topic are warranted for potential neurological and prognostic correlations.

Association between oral microbial dysbiosis and poor functional outcomes in stroke-associated pneumonia patients

BACKGROUND

Despite advances in our understanding of the critical role of the microbiota in stroke patients, the oral microbiome has rarely been reported to be associated with stroke-associated pneumonia (SAP). We sought to profile the oral microbial composition of SAP patients and to determine whether microbiome temporal instability and special taxa are associated with pneumonia progression and functional outcomes.

METHODS

This is a prospective, observational, single-center cohort study that examined patients with acute ischemic stroke (AIS) who were admitted within 24 h of experiencing a stroke event. The patients were divided into three groups based on the occurrence of pneumonia and the use of mechanical ventilation: nonpneumonia group, SAP group, and ventilator-associated pneumonia (VAP) group. We collected oral swabs at different time points post-admission and analyzed the microbiota using 16 S rRNA high-throughput sequencing. The microbiota was then compared among the three groups.

RESULTS

In total, 104 nonpneumonia, 50 SAP and 10 VAP patients were included in the analysis. We found that SAP and VAP patients exhibited significant dynamic differences in the diversity and composition of the oral microbiota and that the magnitude of this dysbiosis and instability increased during hospitalization. Then, by controlling the potential effect of all latent confounding variables, we assessed the changes associated with pneumonia after stroke and explored patients with a lower abundance of Streptococcus were more likely to suffer from SAP. The logistic regression analysis revealed that an increase in specific taxa in the phylum Actinobacteriota was linked to a higher risk of poor outcomes. A model for SAP patients based on oral microbiota could accurately predict 30-day clinical outcomes after stroke onset.

CONCLUSIONS

We concluded that specific oral microbiota signatures could be used to predict illness development and clinical outcomes in SAP patients. We proposed the potential of the oral microbiota as a non-invasive diagnostic biomarker in the clinical management of SAP patients.

CLINICAL TRIAL REGISTRATION

NCT04688138. Registered 29/12/2020, https://clinicaltrials.gov/ct2/show/NCT04688138 .

The Potential of Gut Microbiota in Prediction of Stroke-Associated Pneumonia

BACKGROUND

Stroke-associated pneumonia (SAP) is a common stroke complication, and the changes in the gut microbiota composition may play a role. Our study aimed to evaluate the predictive ability of gut microbiota for SAP.

METHODS

Acute ischemic stroke patients were prospectively enrolled and divided into two groups based on the presence or absence of SAP. The composition of gut microbiota was characterized by the 16S RNA Miseq sequencing. The gut microbiota that differed significantly between groups were incorporated into the conventional risk scores, the Acute Ischemic Stroke-Associated Pneumonia Score (AIS-APS), and the Age, Atrial fibrillation, Dysphagia, Sex, Stroke Severity Score (A2DS2). The predictive performances were assessed in terms of the area under the curve (AUC), the Net Reclassification Improvement (NRI), and the Integrated Discrimination Improvement (IDI) indices.

RESULTS

A total of 135 patients were enrolled, of whom 43 had SAP (31%). The short-chain fatty acids (SCFAs)-producing bacteria, such as Bacteroides, Fusicatenibacter, and Butyricicoccus, were decreased in the SAP group. The integrated models showed better predictive ability for SAP (AUC = 0.813, NRI = 0.333, p = 0.052, IDI = 0.038, p = 0.018, for AIS-APS; AUC = 0.816, NRI = 0.575, p < 0.001, IDI = 0.043, p = 0.007, for A2DS2) in comparison to the differential genera (AUC = 0.699) and each predictive score (AUCAISAPS = 0.777; AUCA2DS2 = 0.777).

CONCLUSIONS

The lower abundance of SCFAs-producing gut microbiota after acute ischemic stroke was associated with SAP and may play a role in SAP prediction.

Neuroinflammation in Acute Ischemic and Hemorrhagic Stroke

PURPOSE OF REVIEW

This review aims to provide an overview of neuroinflammation in ischemic and hemorrhagic stroke, including recent findings on the mechanisms and cellular players involved in the inflammatory response to brain injury.

RECENT FINDINGS

Neuroinflammation is a crucial process following acute ischemic stroke (AIS) and hemorrhagic stroke (HS). In AIS, neuroinflammation is initiated within minutes of the ischemia onset and continues for several days. In HS, neuroinflammation is initiated by blood byproducts in the subarachnoid space and/or brain parenchyma. In both cases, neuroinflammation is characterized by the activation of resident immune cells, such as microglia and astrocytes, and infiltration of peripheral immune cells, leading to the release of pro-inflammatory cytokines, chemokines, and reactive oxygen species. These inflammatory mediators contribute to blood-brain barrier disruption, neuronal damage, and cerebral edema, promoting neuronal apoptosis and impairing neuroplasticity, ultimately exacerbating the neurologic deficit. However, neuroinflammation can also have beneficial effects by clearing cellular debris and promoting tissue repair. The role of neuroinflammation in AIS and ICH is complex and multifaceted, and further research is necessary to develop effective therapies that target this process. Intracerebral hemorrhage (ICH) will be the HS subtype addressed in this review. Neuroinflammation is a significant contributor to brain tissue damage following AIS and HS. Understanding the mechanisms and cellular players involved in neuroinflammation is essential for developing effective therapies to reduce secondary injury and improve stroke outcomes. Recent findings have provided new insights into the pathophysiology of neuroinflammation, highlighting the potential for targeting specific cytokines, chemokines, and glial cells as therapeutic strategies.

The Role of Gut Microbiota in Blood-Brain Barrier Disruption after Stroke

Growing evidence has proved that alterations in the gut microbiota have been linked to neurological disorders including stroke. Structural and functional disruption of the blood-brain barrier (BBB) is observed after stroke. In this context, there is pioneering evidence supporting that gut microbiota may be involved in the pathogenesis of stroke by regulating the BBB function. However, only a few experimental studies have been performed on stroke models to observe the BBB by altering the structure of gut microbiota, which warrant further exploration. Therefore, in order to provide a novel mechanism for stroke and highlight new insights into BBB modification as a stroke intervention, this review summarizes existing evidence of the relationship between gut microbiota and BBB integrity and discusses the mechanisms of gut microbiota on BBB dysfunction and its role in stroke.

Intracranial hemorrhage management in the multi-omics era

Intracranial hemorrhage (ICH) is a devastating disorder. Neuroprotective strategies that prevent tissue injury and improve functional outcomes have been identified in multiple animal models of ICH. However, these potential interventions in clinical trials produced generally disappointing results. With progress in omics, studies of omics data, including genomics, transcriptomics, epigenetics, proteomics, metabolomics, and the gut microbiome, may help promote precision medicine. In this review, we focused on introducing the applications of all omics in ICH and shed light on all of the considerable advantages to systematically analyze the necessity and importance of multiple omics technology in ICH.

Interplay between Gut Microbiota and NLRP3 Inflammasome in Intracerebral Hemorrhage

The pathophysiological process of intracerebral hemorrhage (ICH) is very complex, involving various mechanisms such as apoptosis, oxidative stress and inflammation. As one of the key factors, the inflammatory response is responsible for the pathological process of acute brain injury and is associated with the prognosis of patients. Abnormal or dysregulated inflammatory responses after ICH can aggravate cell damage in the injured brain tissue. The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a multiprotein complex distributed in the cytosol, which can be triggered by multiple signals. The NLRP3 inflammasome is activated after ICH, thus promoting neuroinflammation and aggravating brain edema. In addition, there is evidence that the gut microbiota is crucial in the activation of the NLRP3 inflammasome. The gut microbiota plays a key role in a variety of CNS disorders. Changes in the diversity and species of the gut microbiota affect neuroinflammation through the activation of the NLRP3 inflammasome and the release of inflammatory cytokines. In turn, the gut microbiota composition can be influenced by the activation of the NLRP3 inflammasome. Thereby, the regulation of the microbe-gut-brain axis via the NLRP3 inflammasome may serve as a novel idea for protecting against secondary brain injury (SBI) in ICH patients. Here, we review the recent evidence on the functions of the NLRP3 inflammasome and the gut microbiota in ICH, as well as their interactions, during the pathological process of ICH.