TMAO Promotes NLRP3 Inflammasome Activation of Microglia Aggravating Neurological Injury in Ischemic Stroke Through FTO/IGF2BP2

IGF2BP2 orchestrates global expression and alternative splicing profiles associated with glioblastoma development in U251 cells

Glioblastoma (GBM) is a highly invasive and malignant central nervous system tumor with a median survival duration of 15 months despite multimodal therapy. The insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) has been implicated in various cancers and is known to regulate RNA metabolism and alternative splicing (AS). However, its role in GBM remains unclear. Overexpression of IGF2BP2 led to significant alterations in gene expression, with 472 genes upregulated and 99 downregulated. Gene ontology (GO) analysis indicated enrichment in immune-related biological processes. Notably, IGF2BP2 was found to regulate AS events, with 1372 regulated AS genes (RASGs) and 2096 significantly distinct ASEs identified. Furthermore, IGF2BP2 selectively bound to 3' and 5' untranslated regions (UTRs) via GG[AU]C motifs, and IFIH1 was identified as a direct binding partner and upregulated gene upon IGF2BP2 overexpression. Functional enrichment analysis suggested that IGF2BP2 influences pathways related to RNA splicing and immune responses. Our findings demonstrate that IGF2BP2 plays a crucial role in GBM by modulating the transcriptome and AS events. The upregulation of immune-related genes and the regulation of AS by IGF2BP2 highlight its potential as a therapeutic target in GBM, particularly for immunotherapy. The study provides a foundation for further investigation into the molecular mechanisms of IGF2BP2 in GBM and its implications for cancer treatment.

A gender perspective on diet, microbiome, and sex hormone interplay in cardiovascular disease

A unique interplay between body and environment embeds and reflects host-microbiome interactions that contribute to sex-differential disease susceptibility, symptomatology, and treatment outcomes. These differences derive from individual biological factors, such as sex hormone action, sex-divergent immune processes, X-linked gene dosage effects, and epigenetics, as well as from their interaction across the lifespan. The gut microbiome is increasingly recognized as a moderator of several body systems that are thus impacted by its function and composition. In humans, biological sex components further interact with gender-specific exposures such as dietary preferences, stressors, and life experiences to form a complex whole, requiring innovative methodologies to disentangle. Here, we summarize current knowledge of the interactions among sex hormones, gut microbiota, immune system, and vascular health and their relevance for sex-differential epidemiology of cardiovascular diseases. We outline clinical implications, identify knowledge gaps, and place emphasis on required future studies to address these gaps. In addition, we provide an overview of the caveats associated with conducting cardiovascular research that require consideration of sex/gender differences. While previous work has inspected several of these components separately, here we call attention to further translational utility of a combined perspective from cardiovascular translational research, gender medicine, and microbiome systems biology.

Gut microbiome-derived metabolites in Alzheimer's disease: Regulation of immunity and potential for therapeutics

Alzheimer's disease (AD) is the most common neurodegenerative disorder and cause of dementia. Despite the prevalence of AD, there is a lack of effective disease modifying therapies. Recent evidence indicates that the gut microbiome (GMB) may play a role in AD through its regulation of innate and adaptive immunity. Gut microbes regulate physiology through their production of metabolites and byproducts. Microbial metabolites may be beneficial or detrimental to the pathogenesis and progression of inflammatory diseases. A better understanding of the role GMB-derived metabolites play in AD may lead to the development of therapeutic strategies for AD. In this review, we summarize the function of bioactive GMB-derived metabolites and byproducts and their roles in AD models. We also call for more focus on this area in the gut-brain axis field in order to create effective therapies for AD.

Association of trimethylamine oxide and its precursors with cognitive impairment: a systematic review and meta-analysis

Objectives

The role of trimethylamine oxide (TMAO) in patients with cognitive impairment remains controversial. This study aimed to assess the association between TMAO and its precursors and the prevalence of cognitive impairment.

Methods

PubMed, Embase, and Web of Science databases were searched for studies that met the inclusion criteria from their inception to 14 September 2024, and references were manually searched to identify any additions. Odds ratio (OR) was assessed by random-effects modeling, subgroup analyses to identify potential sources of heterogeneity, and the Newcastle-Ottawa Scale (NOS) and the Agency for Healthcare Research and Quality (AHRQ) Inventory for qualitative evaluation.

Results

Nine studies involving 82,246 participants were included in the analysis. Meta-analyses suggested that elevated TMAO levels were strongly associated with an increased risk of cognitive impairment (OR: 1.39, 95% confidence interval [95%CI]: 1.09-1.77, p < 0.05, I2:60%), and consistent results were obtained across all subgroups examined and sensitivity analyses. However, in the TMAO dose-response meta-analysis and TMAO precursor meta-analyses, the results were not significantly different (dietary choline: OR: 0.93, 95%CI: 0.78-1.10, p = 0.385, I2:68%, plasma choline: OR: 0.65, 95%CI: 0.41-1.02, p = 0.063, I2:76%, plasma betaine: OR: 0.74, 95%CI: 0.52-1.05, p = 0.094, I2:61%).

Conclusion

We found that high TMAO concentrations were positively associated with the risk of cognitive impairment. TMAO is expected to be a potential risk predictor and therapeutic target for cognitive impairment. However, more high-quality studies are needed to further investigate the dose relationship between circulating TMAO concentrations and cognitive impairment.

Systematic review registration

PROSPERO, identifier: CRD42023464543.

Potential Trimethylamine (TMA)-Producing Bacteria in patients with chronic kidney disease undergoing hemodialysis

INTRODUCTION

Trimethylamine (TMA), produced by gut microbiota, is the precursor of trimethylamine-N-oxide (TMAO), a uremic toxin that accumulates in patients with chronic kidney disease (CKD). Elevated TMAO plasma levels are associated with cardiovascular complications and CKD progression.

OBJECTIVE

To evaluate the association between gut microbiota composition and TMAO plasma levels in CKD patients undergoing hemodialysis (HD).

METHODS

This is a cross-sectional study with 25 patients evaluated (60% female, 53 (18) years, body mass index (BMI) 25.8 (6.75) Kg/m2). They were divided into two groups according to their TMAO plasma levels: normal (≤ 7.4 μM) and high (> 7.4 μM). Uremic toxins such as indoxyl sulfate (IS), p-cresyl sulfate (pCS), and indol acetic acid (IAA) were measured with RP-HPLC, and TMAO plasma levels were quantified using LC-MS/MS. Fecal DNA was extracted with a commercial kit, PCR amplified the V4 region of the 16S rRNA gene, and short-read sequencing was performed on the Illumina platform. Dietary intake, anthropometric measurements, and inflammation markers were also evaluated. Nrf2, NF-κB, IL-1β, and NLRP3 mRNA expressions were measured from peripheral blood mononuclear cells (PBMC) using quantitative real-time polymerase chain reaction (qPCR).

RESULTS

There were significant positive correlations between TMAO and plasma levels of pCS, NLPR3 inflammasome mRNA expression, serum phosphorus levels, and negative correlations with dietary lipid intake. The group with TMAO > 7.4 μM showed an increase in the microbiome abundance of Saccharibacteria (genus incertae sedis), Colidextribacter, Dorea, and Staphylococci genera, and a decrease in abundance in the genera Lachnospira, Lactobacilli, and Victivallis. TMAO plasma level was positively correlated with the abundance of bacteria of the genera Colidextribacter and Helicobacter and was negatively correlated with Sphingomanos, Lachnospira, Streptomyces, and Bacillus genera.

CONCLUSION

Saccharibacteria (genus incertae sedis), Colidextribacter, Dorea, and Staphylococci genera showed higher abundance in patients with high TMAO levels. In addition, we observed that elevated plasma TMAO levels are associated with inflammation markers, dietary lipid intake, and serum phosphorus levels in patients undergoing HD.

Long noncoding RNA H19 knockdown promotes angiogenesis via IMP2 after ischemic stroke

AIMS

This study aimed to explore the effects of long noncoding RNA (lncRNA) H19 knockdown on angiogenesis and blood-brain barrier (BBB) integrity following cerebral ischemia/reperfusion (I/R) and elucidate their underlying regulatory mechanisms.

METHODS

A middle cerebral artery occlusion/reperfusion model was used to induce cerebral I/R injury. The cerebral infarct volume and neurological impairment were assessed using 2,3,5-triphenyl-tetrazolium chloride staining and neurobehavioral tests, respectively. Relevant proteins were evaluated using western blotting and immunofluorescence staining. Additionally, a bioinformatics website was used to predict the potential target genes of lncRNA H19. Finally, a rescue experiment was conducted to confirm the potential mechanism.

RESULTS

Silencing of H19 significantly decreased the cerebral infarct volume, enhanced the recovery of neurological function, mitigated BBB damage, and stimulated endothelial cell proliferation following ischemic stroke. Insulin-like growth factor 2 mRNA-binding protein 2 (IMP2) is predicted to be a potential target gene for lncRNA H19. H19 knockdown increased IMP2 protein expression and IMP2 inhibition reversed the protective effects of H19 inhibition.

CONCLUSION

Downregulation of H19 enhances angiogenesis and mitigates BBB damage by regulating IMP2, thereby alleviating cerebral I/R injury.

Exploring Mechanism of Electroacupuncture in Modulating Neuroinflammation Based on Intestinal Flora and Its Metabolites

Neuroinflammatory responses play an important role in the pathogenesis of various diseases, particularly those affecting the central nervous system. Inhibition of neuroinflammation is a crucial therapeutic strategy for the management of central nervous system disorders. The intestinal microbial-gut-brain axis serves as a key regulatory pathway that modulates neuroinflammatory processes. Intestinal flora metabolites such as short-chain fatty acids, indoles and their derivatives, lipopolysaccharides, trimethylamine oxide, and secondary bile acids exert direct or indirect effects on neuroinflammation. Studies have shown that electroacupuncture (EA) modulates the composition of the intestinal microbiota and its metabolites, while also suppressing neuroinflammation by targeting the TLR4/NF- κ B, NLRP3/caspase-1, and microglial cell M2-type transformation pathways. This review discusses the mechanisms by which EA regulates neuroinflammation via intestinal microbiota and its metabolites, providing information and a foundation for further investigation of the precise therapeutic mechanisms of EA in neurological disorders.

Benefits of Taurisolo in Diabetic Patients with Peripheral Artery Disease

Trimethyl-N-oxide (TMAO) has been linked to peripheral artery disease (PAD). TaurisoloⓇ is a natural, balanced phytocomplex containing resveratrol, quercetin, catechins, procianidins, gallic acid, and caffeic acid. Numerous studies have shown that TaurisoloⓇ reduces the damage of TMAO and exerts a protective effect on endothelial cells (ECs). The aim of this randomized, double-blind, single-center study was to evaluate the effects of TaurisoloⓇ on claudication in patients with PAD (Rutheford grade I, category II, Fontaine Classification: Stage IIA, American Medical Association Whole Person Impairment Classification: Class 0-WPI 0%) in two parallel groups of 31 patients. The primary outcomes were an increase in the pain-free walking distance and the ankle/brachial pressure index at the beginning and at the end of the treatment with Taurisolo. The secondary endpoint was the serum TMAO changes. The claudication distance improved by 14.1% in the Taurisolo group and by 2.0% in the placebo group, while the maximal distance increased by 15.8% and 0.6% only, respectively (both p < 0.05). The TMAO plasma levels decreased from 3.97 ± 2.13 micromole/L to 0.87 ± 0.48 (p < 0.0001) in the treated group. All these changes were highly significant both in univariate mixed models as well as in the adjusted model. Ultimately, TaurisoloⓇ might be an effective intervention to ameliorate intermittent claudication.

Pharmacological inhibition of mTORC1 reduces neural death and damage volume after MCAO by modulating microglial reactivity

Ischemic stroke is a sudden and acute disease characterized by neuronal death, increment of reactive gliosis (reactive microglia and astrocytes), and a severe inflammatory process. Neuroinflammation is an early event after cerebral ischemia, with microglia playing a leading role. Reactive microglia involve functional and morphological changes that drive a wide variety of phenotypes. In this context, deciphering the molecular mechanisms underlying such reactive microglial is essential to devise strategies to protect neurons and maintain certain brain functions affected by early neuroinflammation after ischemia. Here, we studied the role of mammalian target of rapamycin (mTOR) activity in the microglial response using a murine model of cerebral ischemia in the acute phase. We also determined the therapeutic relevance of the pharmacological administration of rapamycin, a mTOR inhibitor, before and after ischemic injury. Our data show that rapamycin, administered before or after brain ischemia induction, reduced the volume of brain damage and neuronal loss by attenuating the microglial response. Therefore, our findings indicate that the pharmacological inhibition of mTORC1 in the acute phase of ischemia may provide an alternative strategy to reduce neuronal damage through attenuation of the associated neuroinflammation.

Betaine alleviates cognitive impairment induced by homocysteine through attenuating NLRP3-mediated microglial pyroptosis in an m6A-YTHDF2-dependent manner

Dementia, with homocysteine (Hcy) as an important risk factor, is a severe public health problem in the aging society. Betaine serves as a methyl donor and plays an important role in reducing Hcy. However, the effects and mechanisms of betaine on Hcy-induced cognitive impairment remain unclear. Firstly, SD rats were injected with Hcy (400 μg/kg) through vena caudalis, and betaine (2.5 % w/v) was supplemented via drinking water for 14 days. Betaine supplementation could attenuate Hcy-induced cognitive impairment in the Y maze and novel object recognition tests by repairing brain injury. Meanwhile, microglial activation was observed to be inhibited by betaine supplementation using immunofluorescence and sholl analysis. Secondly, HMC3 cells were treated with betaine, which was found to decrease the ROS level, ameliorate cell membrane rupture, reduce the release of LDH, IL-18 and IL-1β, and attenuate the damage of microglia to neurons. Mechanistically, betaine alleviates cognitive impairment by inhibiting microglial pyroptosis via reducing the expressions of NLRP3, ASC, pro-caspase-1, cleaved-caspase-1, GSDMD, GSDMD-N, IL-18 and IL-1β. Betaine treatment can increase SAM/SAH ratio, confirming its enhancement on methylation capacity. Furthermore, betaine treatment was found to enhance N6-methyladenosine (m6A) modification of NLRP3 mRNA, and reduced the NLRP3 mRNA stability through increasing the expression of the m6A reader YTH N6-methyladenosine RNA binding protein 2 (YTHDF2). Finally, silencing YTHDF2 could reverse the inhibitory effect of betaine on pyroptosis. Our data demonstrated that betaine attenuated Hcy-induced cognitive impairment by suppressing microglia pyroptosis via inhibiting the NLRP3/caspase-1/GSDMD pathway in an m6A-YTHDF2-dependent manner.

FTO-Mediated m6A Modification of FTH1 Inhibits Ferroptosis of Neurons in Neonatal Cerebral Hypoxic Ischemia

FTO alpha-ketoglutarate dependent dioxygenase (FTO) is aberrantly expressed in brain disorders. However, the roles of FTO in neonatal hypoxic-ischemic brain injury (HIE) are still unclear. This study aims to investigate the potential of FTO in neonatal HIE. Oxygen-glucose deprivation (OGD) was used to establish HIE in vitro. mRNA levels were detected by real-time reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). Protein expression was detected by Western blot. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), ferrous iron (Fe2+) and glutathione (GSH) was detected by specific kit. m6A sites were analyzed using SRAMP and further verify by methylated RNA immunoprecipitation (MeRIP) assay. Cell proliferation was determined by Cell Counting Kit-8 (CCK-8) assay. Cell death was determined by propidium iodide (PI) staining. FTO was downregulated in patients with neonatal HIE and OGD-treated neurons. Moreover, FTO mRNA expression was decreased in ferroptosis inducer, especially ferric ammonium citrate (FAC). However, overexpression of FTO inhibited the ferroptosis of neurons. Moreover, FTO-mediated N6-methyladenosine (m6A) modification of ferritin heavy chain 1 (FTH1) suppressed its mRNA expression and stability, inhibiting its protein expression. However, overexpression of FTH1 abrogated the effects of FTO and promoted the ferroptosis of neurons. In summary, FTO functions as a protective role in neonatal HIE via inhibiting FTH1 signaling. Thence, targeting may be a promising strategy for FTO neonatal HIE.

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.