Commensal microbiota affects ischemic stroke outcome by regulating intestinal γδ T cells

An altered gut microbiome in pre-eclampsia: cause or consequence

Hypertensive disorders of pregnancy, including pre-eclampsia, are a leading cause of serious and debilitating complications that affect both the mother and the fetus. Despite the occurrence and the health implications of these disorders there is still relatively limited evidence on the molecular underpinnings of the pathophysiology. An area that has come to the fore with regard to its influence on health and disease is the microbiome. While there are several microbiome niches on and within the body, the distal end of the gut harbors the largest of these impacting on many different systems of the body including the central nervous system, the immune system, and the reproductive system. While the role of the microbiome in hypertensive disorders, including pre-eclampsia, has not been fully elucidated some studies have indicated that several of the symptoms of these disorders are linked to an altered gut microbiome. In this review, we examine both pre-eclampsia and microbiome literature to summarize the current knowledge on whether the microbiome drives the symptoms of pre-eclampsia or if the aberrant microbiome is a consequence of this condition. Despite the paucity of studies, obvious gut microbiome changes have been noted in women with pre-eclampsia and the individual symptoms associated with the condition. Yet further research is required to fully elucidate the role of the microbiome and the significance it plays in the development of the symptoms. Regardless of this, the literature highlights the potential for a microbiome targeted intervention such as dietary changes or prebiotic and probiotics to reduce the impact of some aspects of these disorders.

Exploring the common mechanism of vascular dementia and inflammatory bowel disease: a bioinformatics-based study

Objective

Emerging evidence has shown that gut diseases can regulate the development and function of the immune, metabolic, and nervous systems through dynamic bidirectional communication on the brain-gut axis. However, the specific mechanism of intestinal diseases and vascular dementia (VD) remains unclear. We designed this study especially, to further clarify the connection between VD and inflammatory bowel disease (IBD) from bioinformatics analyses.

Methods

We downloaded Gene expression profiles for VD (GSE122063) and IBD (GSE47908, GSE179285) from the Gene Expression Omnibus (GEO) database. Then individual Gene Set Enrichment Analysis (GSEA) was used to confirm the connection between the two diseases respectively. The common differentially expressed genes (coDEGs) were identified, and the STRING database together with Cytoscape software were used to construct protein-protein interaction (PPI) network and core functional modules. We identified the hub genes by using the Cytohubba plugin. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were applied to identify pathways of coDEGs and hub genes. Subsequently, receiver operating characteristic (ROC) analysis was used to identify the diagnostic ability of these hub genes, and a training dataset was used to verify the expression levels of the hub genes. An alternative single-sample gene set enrichment (ssGSEA) algorithm was used to analyze immune cell infiltration between coDEGs and immune cells. Finally, the correlation between hub genes and immune cells was analyzed.

Results

We screened 167 coDEGs. The main articles of coDEGs enrichment analysis focused on immune function. 8 shared hub genes were identified, including PTPRC, ITGB2, CYBB, IL1B, TLR2, CASP1, IL10RA, and BTK. The functional categories of hub genes enrichment analysis were mainly involved in the regulation of immune function and neuroinflammatory response. Compared to the healthy controls, abnormal infiltration of immune cells was found in VD and IBD. We also found the correlation between 8 shared hub genes and immune cells.

Conclusions

This study suggests that IBD may be a new risk factor for VD. The 8 hub genes may predict the IBD complicated with VD. Immune-related coDEGS may be related to their association, which requires further research to prove.

Gut Microbiota Shape Oligodendrocyte Response after Traumatic Brain Injury

White matter injury (WMI) is thought to be a major contributor to long-term cognitive dysfunctions after traumatic brain injury (TBI). This damage occurs partly due to apoptotic death of oligodendrocyte lineage cells (OLCs) after the injury, triggered directly by the trauma or in response to degenerating axons. Recent research suggests that the gut microbiota modulates the inflammatory response through the modulation of peripheral immune cell infiltration after TBI. Additionally, T-cells directly impact OLCs differentiation and proliferation. Therefore, we hypothesized that the gut microbiota plays a critical role in regulating the OLC response to WMI influencing T-cells differentiation and activation. Gut microbial depletion early after TBI chronically reduced re-myelination, acutely decreased OLCs proliferation, and was associated with increased myelin debris accumulation. Surprisingly, the absence of T-cells in gut microbiota depleted mice restored OLC proliferation and remyelination after TBI. OLCs co-cultured with T-cells derived from gut microbiota depleted mice resulted in impaired proliferation and increased expression of MHC-II compared with T cells from control-injured mice. Furthermore, MHC-II expression in OLCs appears to be linked to impaired proliferation under gut microbiota depletion and TBI conditions. Collectively our data indicates that depletion of the gut microbiota after TBI impaired remyelination, reduced OLCs proliferation with concomitantly increased OLC MHCII expression and required the presence of T cells. This data suggests that T cells are an important mechanistic link by which the gut microbiota modulate the oligodendrocyte response and white matter recovery after TBI.

Brain-Heart Axis and the Inflammatory Response: Connecting Stroke and Cardiac Dysfunction

BACKGROUND

In recent years, the mechanistic interaction between the brain and heart has been explored in detail, which explains the effects of brain injuries on the heart and those of cardiac dysfunction on the brain. Brain injuries are the predominant cause of post-stroke deaths, and cardiac dysfunction is the second leading cause of mortality after stroke onset.

SUMMARY

Several studies have reported the association between brain injuries and cardiac dysfunction. Therefore, it is necessary to study the influence on the heart post-stroke to understand the underlying mechanisms of stroke and cardiac dysfunction. This review focuses on the mechanisms and the effects of cardiac dysfunction after the onset of stroke (ischemic or hemorrhagic stroke).

KEY MESSAGES

The role of the site of stroke and the underlying mechanisms of the brain-heart axis after stroke onset, including the hypothalamic-pituitary-adrenal axis, inflammatory and immune responses, brain-multi-organ axis, are discussed.

Association of plasma sphingosine-1-phosphate levels with disease severity and prognosis after intracerebral hemorrhage

Purpose

Sphingosine-1-phosphate (S1P) is a signaling lipid involved in many biological processes, including inflammatory and immune regulatory responses. The study aimed to determine whether admission S1P levels are associated with disease severity and prognosis after spontaneous intracerebral hemorrhage (ICH).

Methods

Data of 134 patients with spontaneous ICH and 120 healthy controls were obtained from Biological Resource Sample Database of Intracerebral Hemorrhage at the First Affiliated Hospital of Zhengzhou University. Plasma S1P levels were measured. Regression analyses were used to analyze the association between S1P levels and admission and 90-day modified Rankin scale (mRS) scores. Receiver operating characteristic (ROC) curves assessed the predictive value of S1P levels for ICH severity and prognosis.

Results

Patients with ICH exhibited elevated plasma S1P levels compared to the control group (median 286.95 vs. 239.80 ng/mL, p < 0.001). When divided patients into mild-to-moderate and severe groups according to their mRS scores both at admission and discharge, S1P levels were significantly elevated in the severe group compared to the mild-to-moderate group (admission 259.30 vs. 300.54, p < 0.001; 90-day 275.24 vs. 303.25, p < 0.001). The patients were divided into three groups with different concentration gradients, which showed significant statistical differences in admission mRS scores (3 vs. 4 vs. 5, p < 0.001), 90-day mRS scores (2.5 vs. 3 vs. 4, p < 0.001), consciousness disorders (45.5% vs. 68.2% vs. 69.6%, p = 0.033), ICU admission (29.5% vs. 59.1% vs. 89.1%, p < 0.001), surgery (15.9% vs. 47.7% vs. 82.6%, p < 0.001), intraventricular hemorrhages (27.3% vs. 61.4% vs. 65.2%, p < 0.001) and pulmonary infection (25% vs. 47.7% vs. 84.8%, p < 0.001). Multivariate analysis displayed that S1P level was an independent risk factor for disease severity (OR = 1.037, 95% CI = 1.020-1.054, p < 0.001) and prognosis (OR = 1.018, 95% CI = 1.006-1.030, p = 0.003). ROC curves revealed a predictive value of S1P levels with an area under the curve of 0.7952 (95% CI = 0.7144-0.8759, p < 0.001) for disease severity and 0.7105 (95% CI = 0.6227-0.7983, p < 0.001) for prognosis.

Conclusion

Higher admission S1P is associated with worse initial disease severity and 90-day functional outcomes in intracerebral hemorrhage.

Neutrophils Mediate Protection Against Colitis and Carcinogenesis by Controlling Bacterial Invasion and IL22 Production by γδ T Cells

Neutrophils are the most abundant leukocytes in human blood and play a primary role in resistance against invading microorganisms and in the acute inflammatory response. However, their role in colitis and colitis-associated colorectal cancer is still under debate. This study aims to dissect the role of neutrophils in these pathologic contexts by using a rigorous genetic approach. Neutrophil-deficient mice (Csf3r-/- mice) were used in classic models of colitis and colitis-associated colorectal cancer and the role of neutrophils was assessed by histologic, cellular, and molecular analyses coupled with adoptive cell transfer. We also performed correlative analyses using human datasets. Csf3r-/- mice showed increased susceptibility to colitis and colitis-associated colorectal cancer compared with control Csf3r+/+ mice and adoptive transfer of neutrophils in Csf3r-/- mice reverted the phenotype. In colitis, Csf3r-/- mice showed increased bacterial invasion and a reduced number of healing ulcers in the colon, indicating a compromised regenerative capacity of epithelial cells. Neutrophils were essential for γδ T-cell polarization and IL22 production. In patients with ulcerative colitis, expression of CSF3R was positively correlated with IL22 and IL23 expression. Moreover, gene signatures associated with epithelial-cell development, proliferation, and antimicrobial response were enriched in CSF3Rhigh patients. Our data support a model where neutrophils mediate protection against intestinal inflammation and colitis-associated colorectal cancer by controlling the intestinal microbiota and driving the activation of an IL22-dependent tissue repair pathway.

The immune system in neurological diseases: What innate-like T cells have to say

The immune system classically consists of 2 lines of defense, innate and adaptive, both of which interact with one another effectively to protect us against any pathogenic threats. Importantly, there is a diverse subset of cells known as innate-like T cells that act as a bridge between the innate and adaptive immune systems and are pivotal players in eliciting inflammatory immune responses. A growing body of evidence has demonstrated the regulatory impact of these innate-like T cells in central nervous system (CNS) diseases and that such immune cells can traffic into the brain in multiple pathological conditions, which can be typically attributed to the breakdown of the blood-brain barrier. However, until now, it has been poorly understood whether innate-like T cells have direct protective or causative properties, particularly in CNS diseases. Therefore, in this review, our attention is focused on discussing the critical roles of 3 unique subsets of unconventional T cells, namely, natural killer T cells, γδ T cells, and mucosal-associated invariant T cells, in the context of CNS diseases, disorders, and injuries and how the interplay of these immune cells modulates CNS pathology, in an attempt to gain a better understanding of their complex functions.

Novel subsets of peripheral immune cells associated with promoting stroke recovery in mice

AIMS

Peripheral immune cells infiltrating into the brain trigger neuroinflammation after an ischemic stroke. Partial immune cells reprogram their function for neural repair. Which immune cells promote ischemic brain recovery needs further identification.

METHODS

We performed single-cell transcriptomic profiling of CD45high immune cells isolated from the ischemic hemisphere at subacute (5 days) and chronic (14 days) stages after ischemic stroke.

RESULTS

A subset of phagocytic macrophages was associated with neuron projection regeneration and tissue remodeling. We also identified a unique type of T cells with highly expressed macrophage markers, including C1q, Apoe, Hexb, and Fcer1g, which showed high abilities in tissue remodeling, myelination regulation, wound healing, and anti-neuroinflammation. Moreover, natural killer cells decreased cytotoxicity and increased energy and metabolic function in the chronic stage after ischemic stroke. Two subgroups of neutrophils upregulated CCL signals to recruit peripheral immune cells and released CXCL2 to keep self-recruiting at the chronic stage.

CONCLUSIONS

We identified subsets of peripheral immune cells that may provide potential therapeutic targets for promoting poststroke recovery.

Lead exposure exacerbates liver injury in high-fat diet-fed mice by disrupting the gut microbiota and related metabolites

Lead (Pb) is a widespread toxic endocrine disruptor that could cause liver damage and gut microbiota dysbiosis. However, the causal relationship and underlying mechanisms between the gut microbiota and Pb-induced liver injury are unclear. In this study, we investigated the metabolic toxicity caused by Pb exposure in normal chow (Chow) and high-fat diet (HFD) mice and confirmed the causal relationship by fecal microbial transplantation (FMT) and antibiotic cocktail experiments. The results showed that Pb exposure exacerbated HFD-induced hepatic lipid deposition, fibrosis, and inflammation, but it had no significant effect on Chow mice. Pb increased serum lipopolysaccharide (LPS) levels and induced intestinal inflammation and barrier damage by activating TLR4/NFκB/MLCK in HFD mice. Furthermore, Pb exposure disrupted the gut microbiota, reduced short-chain fatty acid (SCFA) concentrations and the colonic SCFA receptors, G protein-coupled receptor (GPR) 41/43/109A, in HFD mice. Additionally, Pb significantly inhibited the hepatic GPR109A-mediated adenosine 5'-monophosphate-activated protein kinase (AMPK) pathway, resulting in hepatic lipid accumulation. FMT from Pb-exposed HFD mice exacerbated liver damage, disturbed lipid metabolic pathways, impaired intestinal barriers, and altered the gut microbiota and metabolites in recipient mice. However, mice exposed to HFD + Pb and HFD mice had similar levels of these biomarkers in microbiota depleted by antibiotics. In conclusion, our study provides new insights into gut microbiota dysbiosis as a potential novel mechanism for human health related to liver function impairment caused by Pb exposure.

Luminol-conjugated cyclodextrin biological nanoparticles for the treatment of severe burn-induced intestinal barrier disruption

Background

The breakdown of intestinal barrier integrity occurs after severe burn injury and is responsible for the subsequent reactions of inflammation and oxidative stress. A new protective strategy for the intestinal barrier is urgently needed due to the limitations of the traditional methods. Recently, the application of nanoparticles has become one of the promising therapies for many inflammation-related diseases or oxidative damage. Herein, we developed a new anti-inflammatory and antioxidant nanoparticle named luminol-conjugated cyclodextrin (LCD) and aimed to evaluate its protective effects in severe burn-induced intestinal injury.

Methods

First, LCD nanoparticles, engineered with covalent conjugation between luminol and β-cyclodextrin (β-CD), were synthesized and examined. Then a mouse burn model was successfully established before the mouse body weight, intestinal histopathological manifestation, permeability, tight junction (TJ) expression and pro-inflammatory cytokines were determined in different groups. The proliferation, apoptosis, migration and reactive oxygen species (ROS) of intestinal epithelial cells (IECs) were assessed. Intraepithelial lymphocytes (IELs) were isolated and cultured for analysis by flow cytometry.

Results

LCD nanoparticle treatment significantly relieved the symptoms of burn-induced intestinal injury in the mouse model, including body weight loss and intestinal permeability abnormalities. Moreover, LCD nanoparticles remarkably recovered the mechanical barrier of the intestine after severe burn, renewed TJ structures, promoted IEC proliferation and migration, and inhibited IEC apoptosis. Mechanistically, LCD nanoparticles dramatically alleviated pro-inflammation factors (tumor necrosis factor-α, IL-17A) and ROS accumulation, which could be highly involved in intestinal barrier disruption. Furthermore, an increase in IL-17A and the proportion of IL-17A+Vγ4+ γδ T subtype cells was also observed in vitro in LPS-treated Vγ4+ γδ T cells, but the use of LCD nanoparticles suppressed this increase.

Conclusions

Taken together, these findings demonstrate that LCD nanoparticles have the protective ability to ameliorate intestinal barrier disruption and provide a therapeutic intervention for burn-induced intestinal injury.

Influence of the brain‑gut axis on neuroinflammation in cerebral ischemia‑reperfusion injury (Review)

Stroke, a debilitating cerebrovascular ailment, poses significant threats to human life and health. The intricate interplay between the gut‑brain‑microbiota axis (GBMA) and cerebral ischemia‑reperfusion has increasingly become a focal point of scientific exploration, emerging as a pivotal research avenue in stroke pathophysiology. In the present review, the authors delved into the nexus between the GBMA and neuroinflammation observed post‑stroke. The analysis underscored the pivotal roles of histone deacetylase 3 and neutrophil extracellular traps subsequent to stroke incidents. The influence of gut microbial compositions and their metabolites, notably short‑chain fatty acids and trimethylamine N‑oxide, on neuroinflammatory processes, was further elucidated. The involvement of immune cells, especially regulatory T‑cells, and the intricate signaling cascades including cyclic GMP‑AMP synthase/stimulator of interferon genes/Toll‑like receptor, further emphasized the complex regulatory mechanisms of GBMA in cerebral ischemia/reperfusion injury (CI/RI). Collectively, the present review offered a comprehensive perspective on the metabolic, immune and inflammatory modulations orchestrated by GBMA, augmenting the understanding of its role in neuroinflammation following CI/RI.

Trimethylamine-N-oxide and cerebral stroke risk: A review

Trimethylamine-N-oxide (TMAO) is a gut microbiota-derived metabolite produced by the action of gut microbiota and the hepatic enzyme Flavin Mono‑oxygenase 3 (FMO3). TMAO level has a positive correlation with the risk of cardiovascular events, including stroke, and their level is influenced mainly by dietary choice and the action of liver enzyme FMO3. TMAO plays a role in the development of atherosclerosis plaque, which is one of the causative factors of the stroke event. Preclinical and clinical investigations on the TMAO and associated stroke risk, severity, and outcomes are summarised in this review. In addition, mechanisms of TMAO-driven vascular dysfunction are also discussed, such as inflammation, oxidative stress, thrombus and foam cell formation, altered cholesterol and bile acid metabolism, etc. Post-stroke inflammatory cascades involving activation of immune cells, i.e., microglia and astrocytes, result in Blood-brain-barrier (BBB) disruption, allowing TMAO to infiltrate the brain and further aggravate inflammation. This event occurs as a result of the activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome pathway through the release of inflammatory cytokines and chemokines that further aggravate the BBB and initiate further recruitment of immune cells in the brain. Thus, it's likely that maintaining TMAO levels and associated gut microbiota could be a promising approach for treating and improving stroke complications.

The role of gut microbiota in cerebrovascular disease and related dementia

In recent years, increasing evidence suggests that commensal microbiota may play an important role not only in health but also in disease including cerebrovascular disease. Gut microbes impact physiology, at least in part, by metabolizing dietary factors and host-derived substrates and then generating active compounds including toxins. The purpose of this current review is to highlight the complex interplay between microbiota, their metabolites. and essential functions for human health, ranging from regulation of the metabolism and the immune system to modulation of brain development and function. We discuss the role of gut dysbiosis in cerebrovascular disease, specifically in acute and chronic stroke phases, and the possible implication of intestinal microbiota in post-stroke cognitive impairment and dementia, and we identify potential therapeutic opportunities of targeting microbiota in this context. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Gamma-delta T cells suppress microbial metabolites that activate striatal neurons and induce repetitive/compulsive behavior in mice

Intestinal γδ T cells play an important role in shaping the gut microbiota, which is critical not only for maintaining intestinal homeostasis but also for controlling brain function and behavior. Here, we found that mice deficient for γδ T cells (γδ-/-) developed an abnormal pattern of repetitive/compulsive (R/C) behavior, which was dependent on the gut microbiota. Colonization of WT mice with γδ-/- microbiota induced R/C behavior whereas colonization of γδ-/- mice with WT microbiota abolished the R/C behavior. Moreover, γδ-/- mice had elevated levels of the microbial metabolite 3-phenylpropanoic acid in their cecum, which is a precursor to hippurate (HIP), a metabolite we found to be elevated in the CSF. HIP reaches the striatum and activates dopamine type 1 (D1R)-expressing neurons, leading to R/C behavior. Altogether, these data suggest that intestinal γδ T cells shape the gut microbiota and their metabolites and prevent dysfunctions of the striatum associated with behavior modulation.

Cornuside protects against ischemic stroke in rats by suppressing the IL-17F/TRAF6/NF-κB pathway via the brain-gut axis

Ischemic stroke is a serious neurological disease with limited therapeutic options; thus, it is particularly important to find effective treatments. Restoration of gut microflora diversity is an important factor in the treatment of ischemic stroke, but the mechanism remains unclear. Cornuside is known for its unique anti-inflammatory and circulation-promoting effects; however, whether it can effectively treat ischemic stroke and its therapeutic mechanisms remain unknown. In this study, we used a rat middle cerebral artery occlusion-reperfusion model (MCAO/R) to mimic ischemic stroke in humans and to assess the cerebral protective effects of cornuside in rats with ischemic stroke. Using 16S rRNA sequencing and RNA sequencing, we explored the cornuside mechanism in the brain-gut axis that confers protection against ischemic stroke. In conclusion, cornuside can inhibit the IL-17F/TRAF6/NF-κB pathway by improving the dysregulation of intestinal microflora, and reduce intestinal inflammation and neuroinflammation, which treated ischemic stroke rats.

Protective effects of butyrate on cerebral ischaemic injury in animal models: a systematic review and meta-analysis

Introduction

Cerebral ischaemic stroke is a common disease that poses a serious threat to human health. Butyrate is an important metabolite of intestinal microorganisms. Recent studies have shown that butyrate has a significant protective effect in animal models of cerebral ischaemic injury.

Objective

The aim of this study was to evaluate the protective effect of butyrate on cerebral ischaemic stroke by meta-analysis, aiming to provide a scientific basis for the clinical application of butyrate in patients with cerebral ischaemia.

Materials and methods

A systematic search was conducted for all relevant studies published before 23 January 2024, in PubMed, Web of Science, Cochrane Library, and Embase. Methodological quality was assessed using Syrcle's risk of bias tool for animal studies. Data were analysed using Rev Man 5.3 software.

Results

A total of nine studies were included, and compared with controls, butyrate significantly increased BDNF levels in the brain (SMD = 2.33, 95%CI = [1.20, 3.47], p < 0.005) and P-Akt expression (SMD = 3.53, 95% CI = [0.97, 6.10], p < 0.05). Butyrate also decreased IL-β levels in the brain (SMD = -2.02, 95% CI = [-3.22, -0.81], p < 0.005), TNF-α levels (SMD = -0.86, 95% CI = [-1.60, -0.12], p < 0.05), and peripheral vascular IL-1β levels (SMD = -2.10, 95%CI = [-3.59, -0.61], p < 0.05). In addition, butyrate reduced cerebral infarct volume (MD = -11.29, 95%CI = [-17.03, -5.54], p < 0.05), mNSS score (MD = -2.86, 95%CI = [-4.12, -1.60], p < 0.005), foot fault score (MD = -7.59, 95%CI = [-9.83, -5, 35], p < 0.005), and Morris water maze time (SMD = -2.49, 95%CI = [-4.42, -0.55], p < 0.05).

Conclusion

The results of this study indicate that butyrate has a protective effect on cerebral ischaemic stroke in animal models, and the mechanism is related to reducing inflammation and inhibiting apoptosis. It provides an evidence-based basis for the future clinical development of butyrate in the treatment of ischaemic stroke.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, CRD42023482844.

Protective effects of fecal microbiota transplantation against ischemic stroke and other neurological disorders: an update

The bidirectional communication between the gut and brain or gut-brain axis is regulated by several gut microbes and microbial derived metabolites, such as short-chain fatty acids, trimethylamine N-oxide, and lipopolysaccharides. The Gut microbiota (GM) produce neuroactives, specifically neurotransmitters that modulates local and central neuronal brain functions. An imbalance between intestinal commensals and pathobionts leads to a disruption in the gut microbiota or dysbiosis, which affects intestinal barrier integrity and gut-immune and neuroimmune systems. Currently, fecal microbiota transplantation (FMT) is recommended for the treatment of recurrent Clostridioides difficile infection. FMT elicits its action by ameliorating inflammatory responses through the restoration of microbial composition and functionality. Thus, FMT may be a potential therapeutic option in suppressing neuroinflammation in post-stroke conditions and other neurological disorders involving the neuroimmune axis. Specifically, FMT protects against ischemic injury by decreasing IL-17, IFN-γ, Bax, and increasing Bcl-2 expression. Interestingly, FMT improves cognitive function by lowering amyloid-β accumulation and upregulating synaptic marker (PSD-95, synapsin-1) expression in Alzheimer's disease. In Parkinson's disease, FMT was shown to inhibit the expression of TLR4 and NF-κB. In this review article, we have summarized the potential sources and methods of administration of FMT and its impact on neuroimmune and cognitive functions. We also provide a comprehensive update on the beneficial effects of FMT in various neurological disorders by undertaking a detailed interrogation of the preclinical and clinical published literature.

Effects of an Akt-activating peptide obtained from walnut protein degradation on the prevention of memory impairment in mice

Akt acts as a central protein influencing multiple pathologies in neurodegenerative diseases including AD and PD, and using Akt activators is a promising management strategy. The current study characterized the effects of an Akt-activating peptide (Glu-Pro-Glu-Val-Leu-Pro, EPEVLR) obtained from walnut protein degradation on D-gal-induced memory impairment in mice. EPEVLR was obtained by hydrolysis of walnut proteins, identification of peptide sequences, and screening for molecular docking sequentially. The MWM test in mice indicated that the oral administration of EPEVLR (80, 200 and 400 mg per kg per day) significantly (p < 0.05) reversed D-gal-induced memory impairment. WB tests of the mouse hippocampus confirmed that EPEVLR could activate Akt by promoting its phosphorylation. In addition, further characterization (including TEM, ELISA, and immunohistochemistry) related to Akt phosphorylation showed lower Aβ and p-tau levels, as well as more autophagosomes than those in the model group. Moreover, the EPEVLR treatment significantly increased Lactobacillus abundance and reduced Helicobacter abundance in the gut microbiome and caused up-regulation of SCFAs and down-regulation of LPS of serum metabolites. Therefore, EPEVLR ingestion reversed cognitive impairment symptoms, possibly related to the activation of Akt and regulation of the intestinal flora pathway. Consumption of an EPEVLR-containing diet is beneficial for treating cognitive dysfunction.

Fecal microbiota transplantation unveils sex-specific differences in a controlled cortical impact injury mouse model

Introduction

Contusion type of traumatic brain injury (TBI) is a major cause of locomotor disability and mortality worldwide. While post-TBI deleterious consequences are influenced by gender and gut dysbiosis, the sex-specific importance of commensal gut microbiota is underexplored after TBI. In this study, we investigated the impact of controlled cortical impact (CCI) injury on gut microbiota signature in a sex-specific manner in mice.

Methods

We depleted the gut microflora of male and female C57BL/6 mice using antibiotic treatment. Thereafter, male mice were colonized by the gut microbiota of female mice and vice versa, employing the fecal microbiota transplantation (FMT) method. CCI surgery was executed using a stereotaxic impactor (Impact One™). For the 16S rRNA gene amplicon study, fecal boli of mice were collected at 3 days post-CCI (dpi).

Results and discussion

CCI-operated male and female mice exhibited a significant alteration in the genera of Akkermansia, Alistipes, Bacteroides, Clostridium, Lactobacillus, Prevotella, and Ruminococcus. At the species level, less abundance of Lactobacillus helveticus and Lactobacillus hamsteri was observed in female mice, implicating the importance of sex-specific bacteriotherapy in CCI-induced neurological deficits. FMT from female donor mice to male mice displayed an increase in genera of Alistipes, Lactobacillus, and Ruminococcus and species of Bacteroides acidifaciens and Ruminococcus gnavus. Female FMT-recipient mice from male donors showed an upsurge in the genus Lactobacillus and species of Lactobacillus helveticus, Lactobacillus hamsteri, and Prevotella copri. These results suggest that the post-CCI neurological complications may be influenced by the differential gut microbiota perturbation in male and female mice.

What we need to know about the germ-free animal models

The gut microbiota (GM), as a forgotten organ, refers to the microbial community that resides in the gastrointestinal tract and plays a critical role in a variety of physiological activities in different body organs. The GM affects its targets through neurological, metabolic, immune, and endocrine pathways. The GM is a dynamic system for which exogenous and endogenous factors have negative or positive effects on its density and composition. Since the mid-twentieth century, laboratory animals are known as the major tools for preclinical research; however, each model has its own limitations. So far, two main models have been used to explore the effects of the GM under normal and abnormal conditions: the isolated germ-free and antibiotic-treated models. Both methods have strengths and weaknesses. In many fields of host-microbe interactions, research on these animal models are known as appropriate experimental subjects that enable investigators to directly assess the role of the microbiota on all features of physiology. These animal models present biological model systems to either study outcomes of the absence of microbes, or to verify the effects of colonization with specific and known microbial species. This paper reviews these current approaches and gives advantages and disadvantages of both models.

The interplay between microbiota and brain-gut axis in epilepsy treatment

The brain-gut axis plays a vital role in connecting the cognitive and emotional centers of the brain with the intricate workings of the intestines. An imbalance in the microbiota-mediated brain-gut axis extends far beyond conditions like Irritable Bowel Syndrome (IBS) and obesity, playing a critical role in the development and progression of various neurological disorders, including epilepsy, depression, Alzheimer's disease (AD), and Parkinson's disease (PD). Epilepsy, a brain disorder characterized by unprovoked seizures, affects approximately 50 million people worldwide. Accumulating evidence suggests that rebuilding the gut microbiota through interventions such as fecal microbiota transplantation, probiotics, and ketogenic diets (KD) can benefit drug-resistant epilepsy. The disturbances in the gut microbiota could contribute to the toxic side effects of antiepileptic drugs and the development of drug resistance in epilepsy patients. These findings imply the potential impact of the gut microbiota on epilepsy and suggest that interventions targeting the microbiota, such as the KD, hold promise for managing and treating epilepsy. However, the full extent of the importance of microbiota in epilepsy treatment is not yet fully understood, and many aspects of this field remain unclear. Therefore, this article aims to provide an overview of the clinical and animal evidence supporting the regulatory role of gut microbiota in epilepsy, and of potential pathways within the brain-gut axis that may be influenced by the gut microbiota in epilepsy. Furthermore, we will discuss the recent advancements in epilepsy treatment, including the KD, fecal microbiota transplantation, and antiseizure drugs, all from the perspective of the gut microbiota.

The Role of the Gut Microbiome in the Development of Acute Pancreatitis

With the explosion research on the gut microbiome in the recent years, much insight has been accumulated in comprehending the crosstalk between the gut microbiota community and host health. Acute pancreatitis (AP) is one of the gastrointestinal diseases associated with significant morbidity and subsequent mortality. Studies have elucidated that gut microbiota are engaged in the pathological process of AP. Herein, we summarize the major roles of the gut microbiome in the development of AP. We then portray the association between dysbiosis of the gut microbiota and the severity of AP. Finally, we illustrate the promises and challenges that arise when seeking to incorporate the microbiome in acute pancreatitis treatment.

Systemic Characterization of the Gut Microbiota Profile after Single Mild Ischemic Stroke and Recurrent Stroke in Mice

It has been estimated that one in four stroke patients may have recurrent stroke within five years after they experienced the first stroke. Furthermore, clinical studies have shown that recurrent stroke negatively affects patient outcomes; the risk of disability and the death rate increase with each recurrent stroke. Therefore, it is urgent to find effective methods to prevent recurrent stroke. The gut microbiota has been proven to play an essential role after ischemic stroke, while sudden ischemia disrupts microbial dysbiosis, and the metabolites secreted by the microbiota also reshape the gut microenvironment. In the present study, we established a recurrent ischemic mouse model. Using this experimental model, we compared the survival rate and ischemic infarction between single MCAO and recurrent MCAO, showing that, when two surgeries were performed, the mouse survival rate dramatically decreased, while the infarction size increased. Fecal samples were collected on day 1, day 3 and day 7 after the first MCAO and day 9 (2 days after the second MCAO) for 16S sequencing, which provided a relatively comprehensive picture of the microbiota changes. By further analyzing the potential metabolic pathways, our data also highlighted several important pathways that were significantly altered after the first and recurrent stroke. In the present study, using an experimental mouse model, we showed that acute ischemic stroke, especially recurrent ischemia, significantly decreased the diversity of the gut microbiota.

Fecal microbiota transplantation regulates the microbiota-gut-spinal cord axis to promote recovery after spinal cord injury

Spinal cord injury (SCI) is devastating for patients, and currently lacks effective treatments. Dysbiosis commonly occurs after SCI and has significant immunomodulatory effects, but its impact on recovery remains unclear. The current study investigated the effects and mechanisms of fecal microbiota transplantation (FMT) in SCI. FMT was administered in a rat model of SCI and spinal pathology, inflammatory cytokines, and gut microbiome composition were assessed. Flow cytometry identified a source of interleukin (IL)-17 in spinal cord tissues, and carboxyfluorescein succimidyl ester labeling tracked γδ T cell migration. In vitro coculture was used to analyze the regulatory mechanisms of γδ T cells. Seahorse analysis was used to profile dendritic cell (DC) metabolism. Here we show that FMT improved spinal pathology and dampened post-injury inflammation. It also corrected post-SCI dysbiosis, increasing levels of the beneficial bacterium Akkermansia. The therapeutic effects of FMT were mediated by IL-17 produced by γδ T cells. FMT regulated γδ T cells via DC-T regulatory cell interaction, and induced metabolic reprogramming in DCs. These findings suggest that FMT represents a promising therapeutic approach for SCI, with potential to target IL-17+ γδ T cells. Elucidating the interconnected pathways between microbiota, immunity, and the spinal cord may facilitate novel treatment strategies.

The contribution of age-related changes in the gut-brain axis to neurological disorders

Trillions of microbes live symbiotically in the host, specifically in mucosal tissues such as the gut. Recent advances in metagenomics and metabolomics have revealed that the gut microbiota plays a critical role in the regulation of host immunity and metabolism, communicating through bidirectional interactions in the microbiota-gut-brain axis (MGBA). The gut microbiota regulates both gut and systemic immunity and contributes to the neurodevelopment and behaviors of the host. With aging, the composition of the microbiota changes, and emerging studies have linked these shifts in microbial populations to age-related neurological diseases (NDs). Preclinical studies have demonstrated that gut microbiota-targeted therapies can improve behavioral outcomes in the host by modulating microbial, metabolomic, and immunological profiles. In this review, we discuss the pathways of brain-to-gut or gut-to-brain signaling and summarize the role of gut microbiota and microbial metabolites across the lifespan and in disease. We highlight recent studies investigating 1) microbial changes with aging; 2) how aging of the maternal microbiome can affect offspring health; and 3) the contribution of the microbiome to both chronic age-related diseases (e.g., Parkinson's disease, Alzheimer's disease and cerebral amyloidosis), and acute brain injury, including ischemic stroke and traumatic brain injury.

Meningeal interleukin-17-producing T cells mediate cognitive impairment in a mouse model of salt-sensitive hypertension

Hypertension (HTN), a disease afflicting over one billion individuals worldwide, is a leading cause of cognitive impairment, the mechanisms of which remain poorly understood. In the present study, in a mouse model of HTN, we find that the neurovascular and cognitive dysfunction depends on interleukin (IL)-17, a cytokine elevated in individuals with HTN. However, neither circulating IL-17 nor brain angiotensin signaling can account for the dysfunction. Rather, IL-17 produced by T cells in the dura mater is the mediator released in the cerebrospinal fluid and activating IL-17 receptors on border-associated macrophages (BAMs). Accordingly, depleting BAMs, deleting IL-17 receptor A in brain macrophages or suppressing meningeal T cells rescues cognitive function without attenuating blood pressure elevation, circulating IL-17 or brain angiotensin signaling. Our data unveil a critical role of meningeal T cells and macrophage IL-17 signaling in the neurovascular and cognitive dysfunction in a mouse model of HTN.

Modulation of Alzheimer's disease brain pathology in mice by gut bacterial depletion: the role of IL-17a

Gut bacteria regulate brain pathology of Alzheimer's disease (AD) patients and animal models; however, the underlying mechanism remains unclear. In this study, 3-month-old APP-transgenic female mice with and without knock-out of Il-17a gene were treated with antibiotics-supplemented or normal drinking water for 2 months. The antibiotic treatment eradicated almost all intestinal bacteria, which led to a reduction in Il-17a-expressing CD4-positive T lymphocytes in the spleen and gut, and to a decrease in bacterial DNA in brain tissue. Depletion of gut bacteria inhibited inflammatory activation in both brain tissue and microglia, lowered cerebral Aβ levels, and promoted transcription of Arc gene in the brain of APP-transgenic mice, all of which effects were abolished by deficiency of Il-17a. As possible mechanisms regulating Aβ pathology, depletion of gut bacteria inhibited β-secretase activity and increased the expression of Abcb1 and Lrp1 in the brain or at the blood-brain barrier, which were also reversed by the absence of Il-17a. Interestingly, a crossbreeding experiment between APP-transgenic mice and Il-17a knockout mice further showed that deficiency of Il-17a had already increased Abcb1 and Lrp1 expression at the blood-brain barrier. Thus, depletion of gut bacteria attenuates inflammatory activation and amyloid pathology in APP-transgenic mice via Il-17a-involved signaling pathways. Our study contributes to a better understanding of the gut-brain axis in AD pathophysiology and highlights the therapeutic potential of Il-17a inhibition or specific depletion of gut bacteria that stimulate the development of Il-17a-expressing T cells.

Intestinal microbiota modulates neuroinflammatory response and brain injury after neonatal hypoxia-ischemia

Premature infants lack a normal intestinal microbial community and also at risk of perinatal hypoxic-ischemic (HI) brain injury, which is considered to be one of the major factors for motor, sensory, and cognitive deficits. We hypothesized that neonatal gut microbiota composition modulated the immune reaction and severity of neonatal H-I brain injury. Neonatal C57BL/6J mouse pups were exposed to H-I protocol consisting of permanent left carotid artery ligation, followed by 8% hypoxia for 60 min. Microbial manipulation groups included 1) antibiotic treatment, E18 (maternal) to P5; 2) antibiotic treatment E18 to P5 + E. coli gavage; 3) antibiotic treatment E18 to P5 + B. infantis gavage; and 4) saline to pups with dams getting fresh water. The extent of brain injury and recovery was measured on MRI. Edematous injury volume was significantly higher in E. coli group than that in B. infantis group and in fresh water group. Gene expression in brains of pro-inflammatory cytokines (IL1β, IL6, IL2, TNF-α and toll-like receptors 2-6) were elevated to a greater extent in the E. coli group at P10, no injury, and at P13, 72 hours after H-I relative to sham control and B. infantis groups. Significant effects of microbiome and brain injury and interaction of these factors were found in abundance of major phyla. The neuroinflammatory response and brain injury after neonatal hypoxia-ischemia are affected by intestinal microbiota, providing opportunities for therapeutic intervention through targeting the early colonization and development of the gut microbiota.

Gut microbiota alterations are associated with functional outcomes in patients of acute ischemic stroke with non-alcoholic fatty liver disease

Introduction

Patients with acute ischemic stroke (AIS) with non-alcoholic fatty liver disease (NAFLD) frequently have poor prognosis. Many evidences suggested that the changes in gut microbiota may play an important role in the occurrence and development of AIS patients with NAFLD. The purpose of this study was to explore microbial characteristics in patients of AIS with NAFLD, and the correlation between gut microbiota and functional outcomes.

Methods

The patients of AIS were recruited and divided into NAFLD group and non-NAFLD group. The stool samples and clinical information were collected. 16 s rRNA sequencing was used to analyze the characteristics of gut microbiota. The patients of AIS with NAFLD were followed-up to evaluate the functional outcomes of disease. The adverse outcomes were determined by modified Rankin scale (mRS) scores at 3 months after stroke. The diagnostic performance of microbial marker in predicting adverse outcomes was assessed by recipient operating characteristic (ROC) curves.

Results

Our results showed that the composition of gut microbiota between non-NAFLD group and NAFLD group were different. The characteristic bacteria in the patients of AIS with NAFLD was that the relative abundance of Dorea, Dialister, Intestinibacter and Flavonifractor were decreased, while the relative abundance of Enorma was increased. Moreover, the characteristic microbiota was correlated with many clinical parameters, such as mRS scores, mean arterial pressure and fasting blood glucose level. In addition, ROC models based on the characteristic microbiota or the combination of characteristic microbiota with independent risk factors could distinguish functional dependence patients and functional independence patients in AIS with NAFLD (area under curve is 0.765 and 0.882 respectively).

Conclusion

These findings revealed the microbial characteristics in patients of AIS with NAFLD, and further demonstrated the predictive capability of characteristic microbiota for adverse outcomes in patients of AIS with NAFLD.

Berberine Mediates the Production of Butyrate to Ameliorate Cerebral Ischemia via the Gut Microbiota in Mice

Ischemic stroke (IS) is a vascular disease group concomitant with high morbidity and mortality. Berberine is a bioactive substance and it has been known to improve stroke, but its mechanism is yet to be proven. Mice were fed with BBR for 14 days. Then, the mice were made into MCAO/R models. Neurological score, infarct volume, neuronal damage and markers associated with inflammation were detected. We tested the changes in intestinal flora in model mice after BBR administration using 16SrRNA sequencing. Chromatography-mass spectrometry was used to detect butyrate chemically. Tissue immunofluorescence was used to detect the changes in the microglia and astroglia in the mice brains. Our findings suggest that berberine improves stroke outcomes by modulating the gut microbiota. Specifically, after MCAO/R mice were given berberine, the beneficial bacteria producing butyric acid increased significantly, and the mice also had significantly higher levels of butyric acid. The administration of butyric acid and an inhibitor of butyric acid synthesis, heptanoyl-CoA, showed that butyric acid improved the stroke outcomes in the model mice. In addition, butyric acid could inhibit the activation of the microglia and astrocytes in the brains of model mice, thereby inhibiting the generation of pro-inflammatory factors IL-6, IL-1β and TNF-α as well as improving stroke outcomes. Our results suggest that berberine may improve stroke outcomes by modulating the gut flora to increase the abundance of butyric acid. These findings elucidate the mechanisms by which berberine improves stroke outcomes and provide some basis for clinical treatment.

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.

Immunomodulatory functions of microorganisms in tissue regenerative healing

External pathogenic microorganisms and commensal microorganisms in the body have either harmful or beneficial impacts on the regenerative repair of tissues, and the immune system plays a crucial regulatory role in this process. This review summarises our current understanding of microorganism-immune system interactions, with a focus on how these interactions impact the renewal and repair ability of tissues, including skin, bone, gut, liver, and nerves. This review concludes with a discussion of the mechanisms by which microbes act on various types of immune cells to affect tissue regeneration, offers potential strategies for using microbial therapies to enhance the regenerative repair function of tissues, and suggest novel therapeutic approaches for regenerative medicine. STATEMENT OF SIGNIFICANCE: Microbiological communities have crucial impacts on human health and illness by participating in energy collection and storage and performing various metabolic processes. External pathogenic microorganisms and commensal microorganisms in the body have either harmful or beneficial impacts on the regenerative repair of tissues, and the immune system plays a critical regulatory role in this process. This study reviews the important correlation between microorganisms and the immune system and investigates the mechanism of various microorganism that participate in the regeneration and repair of tissues and organs by modulating immune system.

Gut microbiota and traumatic central nervous system injuries: Insights into pathophysiology and therapeutic approaches

Traumatic brain injury and spinal cord injury are two distinct but fundamentally similar types of acute insults to the central nervous system (CNS) that often culminate in death or cognitive and motor impairment. Over the past decade, researchers have tapped into research to discover the potential role being played by gut bacteria in CNS. After an acute CNS injury, the altered composition of the gut microbiota disturbs the balance of the bidirectional gut-brain axis, aggravating secondary CNS injury, motor dysfunctions, and cognitive deficits, which worsens the patient's prognosis. Some of the well-known therapeutic interventions which can also be used as adjuvant therapy for alleviating CNS injuries include, the use of pro and prebiotics, fecal microbiota transplantation, and microbial engineering. In this review, we aim to discuss the importance of gut microbes in our nervous system, anatomy, and signaling pathways involved in regulating the gut-brain axis, the alteration of the gut microbiome in CNS injuries, and the therapeutic strategies to target gut microbiomes in traumatic CNS injuries.

Estradiol mediates colonic epithelial protection in aged mice after stroke and is associated with shifts in the gut microbiome

The gut is a major source of bacteria and antigens that contribute to neuroinflammation after brain injury. Colonic epithelial cells (ECs) are responsible for secreting major cellular components of the innate defense system, including antimicrobial proteins (AMP) and mucins. These cells serve as a critical regulator of gut barrier function and maintain host-microbe homeostasis. In this study, we determined post-stroke host defense responses at the colonic epithelial surface in mice. We then tested if the enhancement of these epithelial protective mechanisms is beneficial in young and aged mice after stroke. AMPs were significantly increased in the colonic ECs of young males, but not in young females after experimental stroke. In contrast, mucin-related genes were enhanced in young females and contributed to mucus formation that maintains the distance between the host and gut bacteria. Bacterial community profiling was done using universal amplification of 16S rRNA gene sequences. The sex-specific colonic epithelial defense responses after stroke in young females were reversed with ovariectomy and led to a shift from a predominately mucin response to the enhanced AMP expression seen in males after stroke. Estradiol (E2) replacement prior to stroke in aged females increased mucin gene expression in the colonic ECs. Interestingly, we found that E2 treatment reduced stroke-associated neuronal hyperactivity in the insular cortex, a brain region that interacts with visceral organs such as the gut, in parallel to an increase in the composition of Lactobacillus and Bifidobacterium in the gut microbiota. This is the first study demonstrating sex differences in host defense mechanisms in the gut after brain injury.

Post-stroke immunosuppression: Exploring potential implications beyond infections

Stroke is a leading cause of mortality and disability. It occurs when cerebral blood flow is disrupted via vascular occlusion or rupture, causing tissue damage. Research has extensively examined the role of the immune response in stroke pathophysiology, focusing on infiltrated immune cells and inflammatory molecules. However, the stroke's impact on immune physiology remains underexplored. While initially stroke triggers the activation of peripheral inflammation, a subsequent profound immunosuppression occurs in a matter of hours/days. This response, potentially shielding the brain from excessive inflammation, significantly affects stroke patients. Beyond rendering patients more susceptible to infections, immunosuppression generates diverse consequences by disrupting immune system functions that are crucial for organ homeostasis. This review explores the effects of immunosuppression on stroke patients, shedding light on potential issues in immune organs such as the spleen and bone marrow, as well as non-immune organs like the small intestine, liver and heart. By synthesizing existing literature and offering additional insights, this manuscript highlights the multifaceted impact of post-stroke immunosuppression.

Targeting the blood-brain barrier to delay aging-accompanied neurological diseases by modulating gut microbiota, circadian rhythms, and their interplays

The blood-brain barrier (BBB) impairment plays a crucial role in the pathological processes of aging-accompanied neurological diseases (AAND). Meanwhile, circadian rhythms disruption and gut microbiota dysbiosis are associated with increased morbidity of neurological diseases in the accelerated aging population. Importantly, circadian rhythms disruption and gut microbiota dysbiosis are also known to induce the generation of toxic metabolites and pro-inflammatory cytokines, resulting in disruption of BBB integrity. Collectively, this provides a new perspective for exploring the relationship among circadian rhythms, gut microbes, and the BBB in aging-accompanied neurological diseases. In this review, we focus on recent advances in the interplay between circadian rhythm disturbances and gut microbiota dysbiosis, and their potential roles in the BBB disruption that occurs in AAND. Based on existing literature, we discuss and propose potential mechanisms underlying BBB damage induced by dysregulated circadian rhythms and gut microbiota, which would serve as the basis for developing potential interventions to protect the BBB in the aging population through targeting the BBB by exploiting its links with gut microbiota and circadian rhythms for treating AAND.

Regulatory T cells: A suppressor arm in post-stroke immune homeostasis

The activation of the immune system and the onset of pro- and anti-inflammatory responses play crucial roles in the pathophysiological processes of ischaemic stroke (IS). CD4+ regulatory T (Treg) cells is the main immunosuppressive cell population that is studied in the context of peripheral tolerance, autoimmunity, and the development of chronic inflammatory diseases. In recent years, more studies have focused on immune modulation after IS, and Treg cells have been demonstrated to be essential in the remission of inflammation, nerve regeneration, and behavioural recovery. However, the exact effects of Treg cells in the context of IS remain controversial, with some studies suggesting a negative correlation with stroke outcomes. In this review, we aim to provide a comprehensive overview of the current understanding of Treg cell involvement in post-stroke homeostasis. We summarized the literature focusing on the temporal changes in Treg cell populations after IS, the mechanisms of Treg cell-mediated immunomodulation in the brain, and the potential of Treg cell-based therapies for treatment. The purposes of the current article are to address the importance of Treg cells and inspire more studies to help physicians, as well as scientists, understand the whole map of immune responses during IS.

Gut microbiome-targeted therapies for Alzheimer's disease

The advent of high-throughput 'omics' technologies has improved our knowledge of gut microbiome in human health and disease, including Alzheimer's disease (AD), a neurodegenerative disorder. Frequent bidirectional communications and mutual regulation exist between the gastrointestinal tract and the central nervous system through the gut-brain axis. A large body of research has reported a close association between the gut microbiota and AD development, and restoring a healthy gut microbiota may curb or even improve AD symptoms and progression. Thus, modulation of the gut microbiota has become a novel paradigm for clinical management of AD, and emerging effort has focused on developing potential novel strategies for preventing and/or treating the disease. In this review, we provide an overview of the connection and causal relationship between gut dysbiosis and AD, the mechanisms of gut microbiota in driving AD progression, and the successes and challenges of implementing available gut microbiome-targeted therapies (including probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation) in preventive and/or therapeutic preclinical and clinical intervention studies of AD. Finally, we discuss the future directions in this field.

Sympathetic-Mediated Intestinal Cell Death Contributes to Gut Barrier Impairment After Stroke

Tissue injury induced by stroke is traditionally thought to be localised to the brain. However, there is an accumulating body of evidence to demonstrate that stroke promotes pathophysiological consequences in peripheral tissues including the gastrointestinal system. In this study, we investigated the mechanisms underlying gut permeability after stroke. We utilised the clinically relevant experimental model of stroke called permanent intraluminal middle cerebral artery occlusion (pMCAO) to examine the effect of cerebral ischaemia on the gut. We detected stroke-induced gut permeability at 5 h after pMCAO. At this timepoint, we observed significantly elevated intestinal epithelial cell death in post-stroke mice compared to their sham-operated counterparts. At 24 h after stroke onset when the gut barrier integrity is restored, our findings indicated that post-stroke intestinal epithelium had higher expression of genes associated with fructose metabolism, and hyperplasia of intestinal crypts and goblet cells, conceivably as a host compensatory mechanism to adapt to the impaired gut barrier. Furthermore, we discovered that stroke-induced gut permeability was mediated by the activation of the sympathetic nervous system as pharmacological denervation decreased the stroke-induced intestinal epithelial cell death, goblet cell and crypt hyperplasia, and gut permeability to baseline levels. Our study identifies a previously unknown mechanism in the brain-gut axis by which stroke triggers intestinal cell death and gut permeability.

Immune pathway activation in neurons triggers neural damage after stroke

Ischemic brain injury is a severe medical condition with high incidences in elderly people without effective treatment for the resulting neural damages. Using a unilateral mouse stroke model, we analyze single-cell transcriptomes of ipsilateral and contralateral cortical penumbra regions to objectively reveal molecular events with single-cell resolution at 4 h and 1, 3, and 7 days post-injury. Here, we report that neurons are among the first cells that sense the lack of blood supplies by elevated expression of CCAAT/enhancer-binding protein β (C/EBPβ). To our surprise, the canonical inflammatory cytokine gene targets for C/EBPβ, including interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α), are subsequently induced also in neuronal cells. Neuronal-specific silencing of C/EBPβ or IL-1β and TNF-α substantially alleviates downstream inflammatory injury responses and is profoundly neural protective. Taken together, our findings reveal a neuronal inflammatory mechanism underlying early pathological triggers of ischemic brain injury.

Intermittent Fasting on Neurologic Diseases: Potential Role of Gut Microbiota

As the global population ages, the prevalence of neurodegenerative diseases is surging. These disorders have a multifaceted pathogenesis, entwined with genetic and environmental factors. Emerging research underscores the profound influence of diet on the development and progression of health conditions. Intermittent fasting (IF), a dietary pattern that is increasingly embraced and recommended, has demonstrated potential in improving neurophysiological functions and mitigating pathological injuries with few adverse effects. Although the precise mechanisms of IF's beneficial impact are not yet completely understood, gut microbiota and their metabolites are believed to be pivotal in mediating these effects. This review endeavors to thoroughly examine current studies on the shifts in gut microbiota and metabolite profiles prompted by IF, and their possible consequences for neural health. It also highlights the significance of dietary strategies as a clinical consideration for those with neurological conditions.

γδ T cells: origin and fate, subsets, diseases and immunotherapy

The intricacy of diseases, shaped by intrinsic processes like immune system exhaustion and hyperactivation, highlights the potential of immune renormalization as a promising strategy in disease treatment. In recent years, our primary focus has centered on γδ T cell-based immunotherapy, particularly pioneering the use of allogeneic Vδ2+ γδ T cells for treating late-stage solid tumors and tuberculosis patients. However, we recognize untapped potential and optimization opportunities to fully harness γδ T cell effector functions in immunotherapy. This review aims to thoroughly examine γδ T cell immunology and its role in diseases. Initially, we elucidate functional differences between γδ T cells and their αβ T cell counterparts. We also provide an overview of major milestones in γδ T cell research since their discovery in 1984. Furthermore, we delve into the intricate biological processes governing their origin, development, fate decisions, and T cell receptor (TCR) rearrangement within the thymus. By examining the mechanisms underlying the anti-tumor functions of distinct γδ T cell subtypes based on γδTCR structure or cytokine release, we emphasize the importance of accurate subtyping in understanding γδ T cell function. We also explore the microenvironment-dependent functions of γδ T cell subsets, particularly in infectious diseases, autoimmune conditions, hematological malignancies, and solid tumors. Finally, we propose future strategies for utilizing allogeneic γδ T cells in tumor immunotherapy. Through this comprehensive review, we aim to provide readers with a holistic understanding of the molecular fundamentals and translational research frontiers of γδ T cells, ultimately contributing to further advancements in harnessing the therapeutic potential of γδ T cells.

Advances in the study of IL-17 in neurological diseases and mental disorders

Interleukin-17 (IL-17), a cytokine characteristically secreted by T helper 17 (Th17) cells, has attracted increasing attention in recent years because of its importance in the pathogenesis of many autoimmune or chronic inflammatory diseases. Recent studies have shown that neurological diseases and mental disorders are closely related to immune function, and varying degrees of immune dysregulation may disrupt normal expression of immune molecules at critical stages of neural development. Starting from relevant mechanisms affecting immune regulation, this article reviews the research progress of IL-17 in a selected group of neurological diseases and mental disorders (autism spectrum disorder, Alzheimer's disease, epilepsy, and depression) from the perspective of neuroinflammation and the microbiota-gut-brain axis, summarizes the commonalities, and provides a prospective outlook of target application in disease treatment.

The role of the indoles in microbiota-gut-brain axis and potential therapeutic targets: A focus on human neurological and neuropsychiatric diseases

At present, a large number of relevant studies have suggested that the changes in gut microbiota are related to the course of nervous system diseases, and the microbiota-gut-brain axis is necessary for the proper functioning of the nervous system. Indole and its derivatives, as the products of the gut microbiota metabolism of tryptophan, can be used as ligands to regulate inflammation and autoimmune response in vivo. In recent years, some studies have found that the levels of indole and its derivatives differ significantly between patients with central nervous system diseases and healthy individuals, suggesting that they may be important mediators for the involvement of the microbiota-gut-brain axis in the disease course. Tryptophan metabolites produced by gut microbiota are involved in multiple physiological reactions, take indole for example, it participates in the process of inflammation and anti-inflammatory effects through various cellular physiological activities mediated by aromatic hydrocarbon receptors (AHR), which can influence a variety of neurological and neuropsychiatric diseases. This review mainly explores and summarizes the relationship between indoles and human neurological and neuropsychiatric disorders, including ischemic stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, cognitive impairment, depression and anxiety, and puts forward that the level of indoles can be regulated through various direct or indirect ways to improve the prognosis of central nervous system diseases and reverse the dysfunction of the microbiota-gut-brain axis. This article is part of the Special Issue on "Microbiome & the Brain: Mechanisms & Maladies".

Prolonged administration of total glucosides of paeony improves intestinal immune imbalance and epithelial barrier damage in collagen-induced arthritis rats based on metabolomics-network pharmacology integrated analysis

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by synovial inflammation and joint damage with complex pathological mechanisms. In recent years, many studies have shown that the dysregulation of intestinal mucosal immunity and the damage of the epithelial barrier are closely related to the occurrence of RA. Total glucosides of paeony (TGP) have been used clinically for the treatment of RA in China for decades, while the pharmacological mechanism is still uncertain. The purpose of this study was to investigate the regulatory effect and mechanism of TGP on intestinal immunity and epithelial barrier in RA model rats. The results showed that TGP alleviated immune hyperfunction by regulating the ratio of CD3+, CD4+ and CD8+ in different lymphocyte synthesis sites of the small intestine, including Peyer's patches (PPs), intraepithelial lymphocytes (IELs), and lamina propria lymphocytes (LPLs). Specially, TGP first exhibited immunomodulatory effects on sites close to the intestinal lumen (IELs and LPLs), and then on PPs far away from the intestinal lumen as the administration time prolonged. Meanwhile, TGP restores the intestinal epithelial barrier by upregulating the ratio of villi height (V)/crypt depth (C) and expression of tight junction proteins (ZO-1, occludin). Finally, the integrated analysis of metabolomics-network pharmacology was also used to explore the possible regulation mechanism of TGP on the intestinal tract. Metabolomics analysis revealed that TGP reversed the intestinal metabolic profile disturbance in CIA rats, and identified 32 biomarkers and 163 corresponding targets; network pharmacology analysis identified 111 potential targets for TGP to treat RA. By intersecting the results of the two, three key targets such as ADA, PNP and TYR were determined. Pharmacological verification experiments showed that the levels of ADA and PNP in the small intestine of CIA rats were significantly increased, while TGP significantly decreased their ADA and PNP levels. In conclusion, purine metabolism may play an important role in the process of TGP improving RA-induced intestinal immune imbalance and impaired epithelial barrier.

Enteroendocrine cell regulation of the gut-brain axis

Enteroendocrine cells (EECs) are an essential interface between the gut and brain that communicate signals about nutrients, pain, and even information from our microbiome. EECs are hormone-producing cells expressed throughout the gastrointestinal epithelium and have been leveraged by pharmaceuticals like semaglutide (Ozempic, Wegovy), terzepatide (Mounjaro), and retatrutide (Phase 2) for diabetes and weight control, and linaclotide (Linzess) to treat irritable bowel syndrome (IBS) and visceral pain. This review focuses on role of intestinal EECs to communicate signals from the gut lumen to the brain. Canonically, EECs communicate information about the intestinal environment through a variety of hormones, dividing EECs into separate classes based on the hormone each cell type secretes. Recent studies have revealed more diverse hormone profiles and communication modalities for EECs including direct synaptic communication with peripheral neurons. EECs known as neuropod cells rapidly relay signals from gut to brain via a direct communication with vagal and primary sensory neurons. Further, this review discusses the complex information processing machinery within EECs, including receptors that transduce intraluminal signals and the ion channel complement that govern initiation and propagation of these signals. Deeper understanding of EEC physiology is necessary to safely treat devastating and pervasive conditions like irritable bowel syndrome and obesity.

Mood swings are causally associated with intracranial aneurysm subarachnoid hemorrhage: A Mendelian randomization study

BACKGROUND

Mood swings have been observed in patients with intracranial aneurysm (IA), but it is still unknown whether mood swings can affect IA.

AIM

To explore the causal association between mood swings or experiencing mood swings and IA through a two-sample Mendelian randomization (MR) study.

METHODS

Summary-level statistics of mood swings, experiencing mood swings, IA, aneurysm-associated subarachnoid hemorrhage (aSAH), and non-ruptured IA (uIA) were collected from the genome-wide association study. Two-sample MR and various sensitivity analyses were employed to explore the causal association between mood swings or experiencing mood swings and IA, or aSAH, or uIA. The inverse-variance weighted method was used as the primary method.

RESULTS

Genetically determined mood swings (odds ratio [OR] = 5.23, 95% confidence interval (95%CI): 1.65-16.64, p = .005) and experiencing mood swings (OR = 2.50, 95%CI: 1.37-4.57, p = .003) were causally associated with an increased risk of IA. Mood swings (OR = 5.67, 95%CI: 1.40-23.04, p = .015) and experiencing mood swings were causally associated with the risk of aSAH (OR = 2.91, 95%CI: 1.47-5.75, p = .002). Neither mood swings (OR = 1.95, 95%CI: .31-12.29, p = .478) nor experiencing mood swings (OR = 1.20, 95%CI: .48-3.03, p = .693) were associated with uIA.

CONCLUSIONS

Mood swings and experiencing mood swings increased the risk of IA and aSAH incidence. These results suggest that alleviating mood swings may reduce IA rupture incidence and aSAH incidence.