Co-exposure to inorganic arsenic and fluoride prominently disrupts gut microbiota equilibrium and induces adverse cardiovascular effects in offspring rats

Alterations of gut microbiota and its metabolomics in children with 6PPDQ, PBDE, PCB, and metal(loid) exposure

The composition and metabolites of the gut microbiota can be altered by environmental pollutants. However, the effect of co-exposure to multiple pollutants on the human gut microbiota has not been sufficiently studied. In this study, gut microorganisms and their metabolites were compared between 33 children from Guiyu, an e-waste dismantling and recycling area, and 34 children from Haojiang, a healthy environment. The exposure level was assessed by estimating the daily intake (EDI) of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), 6PPD-quinone (6PPDQ), and metal(loid)s in kindergarten dust. Significant correlations were found between the EDIs of 6PPDQ, BDE28, PCB52, Ni, Cu, and the composition of gut microbiota and specific metabolites. The Bayesian kernel machine regression model showed negative correlations between the EDIs of five pollutants (6PPDQ, BDE28, PCB52, Ni, and Cu) and the composition of gut microbiota. The EDIs of these five pollutants were positively correlated with the levels of the metabolite 2,4-diaminobutyric acid, while negatively correlated with the levels of d-erythro-sphingosine and d-threitol. Our study suggests that exposure to 6PPDQ, BDE28, PCB52, Ni, and Cu in kindergarten dust is associated with alterations in the composition and metabolites of the gut microbiota. These alterations may be associated with children's health.

Intestinal microbiota by angiotensin receptor blocker therapy exerts protective effects against hypertensive damages

Dysbiosis of the gut microbiota has been implicated in hypertension, and drug-host-microbiome interactions have drawn considerable attention. However, the influence of angiotensin receptor blocker (ARB)-shaped gut microbiota on the host is not fully understood. In this work, we assessed the alterations of blood pressure (BP), vasculatures, and intestines following ARB-modified gut microbiome treatment and evaluated the changes in the intestinal transcriptome and serum metabolome in hypertensive rats. Hypertensive patients with well-controlled BP under ARB therapy were recruited as human donors, spontaneously hypertensive rats (SHRs) receiving normal saline or valsartan were considered animal donors, and SHRs were regarded as recipients. Histological and immunofluorescence staining was used to assess the aorta and small intestine, and 16S rRNA amplicon sequencing was performed to examine gut bacteria. Transcriptome and metabonomic analyses were conducted to determine the intestinal transcriptome and serum metabolome, respectively. Notably, ARB-modified fecal microbiota transplantation (FMT), results in marked decreases in systolic BP levels, collagen deposition and reactive oxygen species accumulation in the vasculature, and alleviated intestinal structure impairments in SHRs. These changes were linked with the reconstruction of the gut microbiota in SHR recipients post-FMT, especially with a decreased abundance of Lactobacillus, Aggregatibacter, and Desulfovibrio. Moreover, ARB-treated microbes contributed to increased intestinal Ciart, Per1, Per2, Per3, and Cipc gene levels and decreased Nfil3 and Arntl expression were detected in response to ARB-treated microbes. More importantly, circulating metabolites were dramatically reduced in ARB-FMT rats, including 6beta-Hydroxytestosterone and Thromboxane B2. In conclusion, ARB-modified gut microbiota exerts protective roles in vascular remodeling and injury, metabolic abnormality and intestinal dysfunctions, suggesting a pivotal role in mitigating hypertension and providing insights into the cross-talk between antihypertensive medicines and the gut microbiome.

D-Limonene Alleviates Oxidative Stress Injury of the Testis Induced by Arsenic in Rat

Long-term exposure to arsenic can lead to testicular damage and lower sperm quality in males, which is mediated by increased arsenic-induced oxidative stress and other damage mechanisms. D-Limonene, which is rich in oranges, lemons, oranges, grapes and other natural fruits, can relieve doxorubicin (DOX)-induced kidney injury and CCL4-induced cardiac toxicity by inhibiting oxidative stress and inflammatory response. The antioxidant and anti-inflammatory properties of D-limonene motivate us to further explore whether it can reduce arsenic-induced testicular injury. To verify this scientific hypothesis, testicular pathology, testicular oxidative stress levels and sperm motility were determined after intervention with D-limonene in rats chronically exposed to arsenic. As expected, long-term arsenic exposure caused testicular tissue structure disturbances, increased levels of oxidative stress, and decreased sperm activation, all of which were significantly inhibited due to treatment with D-limonene. In conclusion, our data reveal a previously unproven beneficial effect of D-limonene, namely that D-limonene can inhibit arsenic-induced testicular injury, and also provide theoretical and experimental basis for the application of D-limonene in the treatment of arsenic-induced testicular injury.

Didactical approaches and insights into environmental processes and cardiovascular hazards of arsenic contaminants

Arsenic, as a metalloid, has the ability to move and transform in different environmental media. Its widespread contamination has become a significant environmental problem and public concern. Arsenic can jeopardize multiple organs through various pathways, influenced by environmental bioprocesses. This article provides a comprehensive overview of current research on the cardiovascular hazards of arsenic. A bibliometric analysis revealed that there are 376 papers published in 145 journals, involving 40 countries, 631 institutions, and 2093 authors, all focused on arsenic-related concerns regarding cardiovascular health. China and the U.S. have emerged as the central hubs of collaborative relationships and have the highest number of publications. Hypertension and atherosclerosis are the most extensively studied topics, with redox imbalance, apoptosis, and methylation being the primary mechanistic clues. Cardiovascular damage caused by arsenic includes arrhythmia, cardiac remodeling, vascular leakage, and abnormal angiogenesis. However, the current understanding is still inadequate over cardiovascular impairments, underlying mechanisms, and precautionary methods of arsenic, thus calling an urgent need for further studies to bridge the gap between environmental processes and arsenic hazards.

Could the gut microbiota be capable of making individuals more or less susceptible to environmental toxicants?

Environmental toxicants are chemical substances capable to impair environmental quality and exert adverse effects on humans and other animals. The main routes of exposure to these pollutants are through the respiratory tract, skin, and oral ingestion. When ingested orally, they will encounter trillions of microorganisms that live in a community - the gut microbiota (GM). While pollutants can disrupt the GM balance, GM plays an essential role in the metabolism and bioavailability of these chemical compounds. Under physiological conditions, strategies used by the GM for metabolism and/or excretion of xenobiotics include reductive and hydrolytic transformations, lyase and functional group transfer reactions, and enzyme-mediated functional transformations. Simultaneously, the host performs metabolic processes based mainly on conjugation, oxidation, and hydrolysis reactions. Thus, due to the broad variety of bacterial enzymes present in GM, the repertoire of microbial transformations of chemicals is considered a key component of the machinery involved in the metabolism of pollutants in humans and other mammals. Among pollutants, metals deserve special attention once contamination by metals is a worldwide problem, and their adverse effects can be observed even at very low concentrations due to their toxic properties. In this review, bidirectional interaction between lead, arsenic, cadmium, and mercury and the host organism and its GM will be discussed given the most recent literature, presenting an analysis of the ability of GM to alter the host organism's susceptibility to the toxic effects of heavy metals, as well as evaluating the extent to which interventions targeting the microbiota could be potential initiatives to mitigate the adverse effects resulting from poisoning by heavy metals. This study is the first to highlight the overlap between some of the bacteria found to be altered by metal exposure and the bacteria that also aid the host organism in the metabolism of these metals. This could be a key factor to determine the beneficial species able to minimize the toxicity of metals in future therapeutic approaches.

ASC/Caspase-1-activated endothelial cells pyroptosis is involved in vascular injury induced by arsenic combined with high-fat diet

Environmental arsenic (As) or high-fat diet (HFD) exposure alone are risk factors for the development of cardiovascular disease (CVDs). However, the effects and mechanisms of co-exposure to As and HFD on the cardiovascular system remain unclear. The current study aimed to investigate the combined effects of As and HFD on vascular injury and shed some light on the underlying mechanisms. The results showed that co-exposure to As and HFD resulted in a significant increase in serum lipid levels and significant lipid accumulation in the aorta of rats compared with exposure to As or HFD alone. Meanwhile, the combined exposure altered blood pressure and disrupted the morphological structure of the abdominal aorta in rats. Furthermore, As combined with HFD exposure upregulated the expression of vascular endothelial cells pyroptosis-related proteins (ASC, Pro-caspase-1, Caspase-1, IL-18, IL-1β), as well as the expression of vascular endothelial adhesion factors (VCAM-1 and ICAM-1). More importantly, we found that with increasing exposure time, vascular injury-related indicators were significantly higher in the combined exposure group compared with exposure to As or HFD alone, and the vascular injury was more severe in female rats compared with male rats. Taken together, these results suggested that the combination of As and HFD induced vascular endothelial cells pyroptosis through activation of the ASC/Caspase-1 pathway. Therefore, vascular endothelial cells pyroptosis may be a potential molecular mechanism for vascular injury induced by As combined with HFD exposure.

Identifying Serum Metabolites and Gut Bacterial Species Associated with Nephrotoxicity Caused by Arsenic and Fluoride Exposure

Co-contamination of arsenic (As) and fluoride (F) is widely distributed in groundwater, which are known risk factors for the nephrotoxicity. Emerging evidence has linked environmentally associated nephrotoxicity with the disturbance of gut microbiota and blood metabolites. In this study, we generated gut microbiota and blood metabolomic profile and identified multiple serum metabolites and gut bacteria species, which were associated with kidney injury on rat model exposed to As and F alone or combined. Combined As and F exposure significantly increased creatinine level. Abnormal autophagosomes and lysosome were observed, and the autophagic genes were enhanced in kidney tissue after single and combined As and F exposure. The metabolome data showed that single and combined As and F exposure remarkably altered the serum metabolites associated with the proximal tubule reabsorption function pathway, with glutamine and alpha-ketoglutarate level decreased in all exposed group. Furthermore, phosphatidylethanolamine (PE), the key contributor of autophagosomes, was decreased significantly in As and F + As exposed groups during the screen of autophagy-animal pathway. Multiple altered gut bacterial microbiota at phylum and species levels post As and F exposure were associated with targeted kidney injury, including p_Bacteroidetes, s_Chromohalobacter_unclassified, s_Halomonas_unclassified, s_Ignatzschineria_unclassified, s_Bacillus_subtilis, and s_Brevundimonas_sp._NA6. Meanwhile, our analysis indicated that As and F co-exposure possessed an interactive influence on gut microbiota. In conclusion, single or combined As and F exposure leads to the disruption of serum metabolic and gut microbiota profiles. Multiple metabolites and bacterial species are identified and associated with nephrotoxicity, which have potential to be developed as biomarkers of As and/or F-induced kidney damage.

Fisetin attenuates arsenic and fluoride subacute co-exposure induced neurotoxicity via regulating TNF-α mediated activation of NLRP3 inflammasome

Groundwater is considered safe, however, the occurrence of contaminants like arsenic and fluoride has raised a major healthcare concern. Clinical studies suggested that arsenic and fluoride co-exposure induced neurotoxicity, however efforts to explore safe and effective management of such neurotoxicity are limited. Therefore, we investigated the ameliorative effect of Fisetin against arsenic and fluoride subacute co-exposure-induced neurotoxicity, and associated biochemical and molecular changes. Male BALB/c mice Arsenic (NaAsO₂: 50mg/L) and fluoride (NaF: 50mg/L) were exposed to drinking water and fisetin (5, 10, and 20mg/kg/day) was administered orally for 28 days. The neurobehavioral changes were recorded in the open field, rotarod, grip strength, tail suspension, forced swim, and novel object recognition test. The co-exposure resulted in anxiety-like behaviour, loss of motor coordination, depression-like behaviour, and loss of novelty-based memory, along with enhanced prooxidant, inflammatory markers and loss of cortical and hippocampal neurons. The treatment with fisetin reversed the co-exposure-induced neurobehavioral deficit along with restoration of redox & inflammatory milieu, and cortical and hippocampal neuronal density. Apart from antioxidants, inhibition of TNF-α/ NLRP3 expression has been suggested as one of the plausible neuroprotective mechanisms of Fisetin in this study.

Urinary microbiota and metabolic signatures associated with inorganic arsenic-induced early bladder lesions

Inorganic arsenic (iAs) contamination in drinking water is a global public health problem, and exposure to iAs is a known risk factor for bladder cancer. Perturbation of urinary microbiome and metabolome induced by iAs exposure may have a more direct effect on the development of bladder cancer. The aim of this study was to determine the impact of iAs exposure on urinary microbiome and metabolome, and to identify microbiota and metabolic signatures that are associated with iAs-induced bladder lesions. We evaluated and quantified the pathological changes of bladder, and performed 16S rDNA sequencing and mass spectrometry-based metabolomics profiling on urine samples from rats exposed to low (30 mg/L NaAsO₂) or high (100 mg/L NaAsO₂) iAs from early life (in utero and childhood) to puberty. Our results showed that iAs induced pathological bladder lesions, and more severe effects were noticed in the high-iAs group and male rats. Furthermore, six and seven featured urinary bacteria genera were identified in female and male offspring rats, respectively. Several characteristic urinary metabolites, including Menadione, Pilocarpine, N-Acetylornithine, Prostaglandin B1, Deoxyinosine, Biopterin, and 1-Methyluric acid, were identified significantly higher in the high-iAs groups. In addition, the correlation analysis demonstrated that the differential bacteria genera were highly correlated with the featured urinary metabolites. Collectively, these results suggest that exposure to iAs in early life not only causes bladder lesions, but also perturbs urinary microbiome composition and associated metabolic profiles, which shows a strong correlation. Those differential urinary genera and metabolites may contribute to bladder lesions, suggesting a potential for development of urinary biomarkers for iAs-induced bladder cancer.

Co-exposure to arsenic and fluoride to explore the interactive effect on oxidative stress and autophagy in myocardial tissue and cell

Co-contamination of arsenic and fluoride is widely distributed in groundwater. However, little is known about the interactively influence of arsenic and fluoride, especially the combined mechanism in cardiotoxicity. Cellular and animal models exposure to arsenic and fluoride were established to assess the oxidative stress and autophagy mechanism of cardiotoxic damage using the factorial design, a widely used statistical method for assessing two factor interventions. In vivo, combined exposure to high arsenic (50 mg/L) and high fluoride (100 mg/L) induced myocardial injury. The damage is accompanied by accumulation of myocardial enzyme, mitochondrial disorder, and excessive oxidative stress. Further experiment identified that arsenic and fluoride induced the accumulation of autophagosome and increased expression level of autophagy related genes during the cardiotoxicity process. These findings were further demonstrated through the in vitro model of arsenic and fluoride-treated the H9c2 cells. Additionally, combined of arsenic-fluoride exposure possesses the interactively influence on oxidative stress and autophagy, contributing to the myocardial cell toxicity. In conclusion, our data suggest that oxidative stress and autophagy are involved in the process of cardiotoxic injury, and that these indicators showed interaction effect in response to the combined exposure of arsenic and fluoride.

Does fluoride exposure impact on the human microbiome?

Fluoride is added to drinking water in some countries to prevent tooth decay (caries). There is no conclusive evidence that community water fluoridation (CWF) at WHO recommended concentrations for caries prevention has any harmful effects. However, research is ongoing regarding potential effects of ingested fluoride on human neurodevelopment and endocrine dysfunction. Simultaneously, research has emerged highlighting the significance of the human microbiome in gastrointestinal and immune health. In this review we evaluate the literature examining the effect of fluoride exposure on the human microbiome. Unfortunately, none of the studies retrieved examined the effects of ingested fluoridated water on the human microbiome. Animal studies generally examined acute fluoride toxicity following ingestion of fluoridated food and water and conclude that fluoride exposure can detrimentally perturb the normal microbiome. These data are difficult to extrapolate to physiologically relevant human exposure dose ranges and the significance to humans living in areas with CWF requires further investigation. Conversely, evidence suggests that the use of fluoride containing oral hygiene products may have beneficial effects on the oral microbiome regarding caries prevention. Overall, while fluoride exposure does appear to impact the human and animal microbiome, the long-term consequences of this requires further study.

Contemporary Comprehensive Review on Arsenic-Induced Male Reproductive Toxicity and Mechanisms of Phytonutrient Intervention

Arsenic (As) is a poisonous metalloid that is toxic to both humans and animals. Drinking water contamination has been linked to the development of cancer (skin, lung, urinary bladder, and liver), as well as other disorders such as diabetes and cardiovascular, gastrointestinal, neurological, and developmental damage. According to epidemiological studies, As contributes to male infertility, sexual dysfunction, poor sperm quality, and developmental consequences such as low birth weight, spontaneous abortion, and small for gestational age (SGA). Arsenic exposure negatively affected male reproductive systems by lowering testicular and accessory organ weights, and sperm counts, increasing sperm abnormalities and causing apoptotic cell death in Leydig and Sertoli cells, which resulted in decreased testosterone synthesis. Furthermore, during male reproductive toxicity, several molecular signalling pathways, such as apoptosis, inflammation, and autophagy are involved. Phytonutrient intervention in arsenic-induced male reproductive toxicity in various species has received a lot of attention over the years. The current review provides an in-depth summary of the available literature on arsenic-induced male toxicity, as well as therapeutic approaches and future directions.

Fluoride induced leaky gut and bloom of Erysipelatoclostridium ramosum mediate the exacerbation of obesity in high-fat-diet fed mice

INTRODUCTION

Fluoride is widely presented in drinking water and foods. A strong relation between fluoride exposure and obesity has been reported. However, the potential mechanisms on fluoride-induced obesity remain unexplored. Objectives and methods The effects of fluoride on the obesity were investigated using mice model. Furthermore, the role of gut homeostasis in exacerbation of the obesity induced by fluoride was evaluated. Results The results showed that fluoride alone did not induce obesity in normal diet (ND) fed mice, whereas, it could trigger exacerbation of obesity in high-fat diet (HFD) fed mice. Fluoride impaired intestinal barrier and activated Toll-like receptor 4 (TLR4) signaling to induce obesity, which was further verified in TLR4^-/- mice. Furthermore, fluoride could deteriorate the gut microbiota in HFD mice. The fecal microbiota transplantation from fluoride-induced mice was sufficient to induce obesity, while the exacerbation of obesity by fluoride was blocked upon gut microbiota depletion. The fluoride-induced bloom of Erysipelatoclostridium ramosum was responsible for exacerbation of obesity. In addition, a potential strategy for prevention of fluoride-induced obesity was proposed by intervention with polysaccharides from Fuzhuan brick tea. Conclusion Overall, these results provide the first evidence of a comprehensive cross-talk mechanism between fluoride and obesity in HFD fed mice, which is mediated by gut microbiota and intestinal barrier. E. ramosum was identified as a crucial mediator of fluoride induced obesity, which could be explored as potential target for prevention and treatment of obesity with exciting translational value.

High fat diets induce early changes in gut microbiota that may serve as markers of ulterior altered physiological and biochemical parameters related to metabolic syndrome. Effect of virgin olive oil in comparison to butter

Butter and virgin olive oil (EVOO) are two fats differing in their degree of saturation and insaponifiable fraction. EVOO, enriched in polyphenols and other minority components, exerts a distinct effect on health. Using next generation sequencing, we have studied early and long-term effects of both types of fats on the intestinal microbiota of mice, finding significant differences between the two diets in the percentage of certain bacterial taxa, correlating with hormonal, physiological and metabolic parameters in the host. These correlations are not only concomitant, but most noticeably some of the changes detected in the microbial percentages at six weeks are correlating with changes in physiological values detected later, at twelve weeks. Desulfovibrionaceae/Desulfovibrio/D. sulfuricans stand out by presenting at six weeks a statistically significant higher percentage in the butter-fed mice with respect to the EVOO group, correlating with systolic blood pressure, food intake, water intake and insulin at twelve weeks. This not only suggests an early implication in the probability of developing altered physiological and biochemical responses later on in the host lifespan, but also opens the possibility of using this genus as a marker in the risk of suffering different pathologies in the future.

Ambient NO2 exposure induced cardiotoxicity associated with gut microbiome dysregulation and glycerophospholipid metabolism disruption

An average daily increase of 10 μg/m³ in NO₂ concentrations could lead to an increased mortality in cardiovascular, cerebrovascular of 1.89%, 2.07%, but the mechanism by which NO₂ contributes to cardiotoxicity is rarely reported. In order to assess the cardiotoxicity of NO₂ inhalation (5 ppm), we firstly investigate the change of gut microbiota, serum metabonomics and cardiac proteome. Non-targeted LC-MS/MS metabonomics showed that NO₂ stress could perturb the glycerophospholipid metabolism in the serum, which might destabilize the bilayer configuration of cardiac lipid membranes. Furthermore, we observed that NO₂ inhalation caused augmented intercellular gap and inflammatory infiltration in the heart. Although 16 S rRNA gene amplification sequencing demonstrated that NO₂ exposure did not influence the intestinal microbial abundance and diversity, but glycerophospholipid metabolism disruption might be finally reflected in gut microbiom dysregulation, such as Sphingomonas, Koribacter, Actinomarina and Bradyrhizobium Turicibacter, Rothia, Globicatella and Aerococcus. Proteome mining revealed that differentially expressed genes (DEGs) in the heart after NO₂ stress were involved in necroptosis, mitophagy and ferroptosis. We further revealed that NO₂ increased the number of cardiac mitochondria with depletion of cristae by regulating the expression of Mfn2 and Hsp70. This study indicating Mfn2-meidcated imbalanced mitochondrial dynamics as a potential mechanism after NO₂-induced heart injury and suggesting microbiome dysregulation/glycerophospholipid metabolism exerts critical roles in cardiotoxicity caused by NO₂.

Combined effects of arsenic and 2,2-dichloroacetamide on different cell populations of zebrafish liver

Arsenic (As) and disinfection by-products are important health risk factors in the water environment. However, their combined effects on different cell populations in the liver are not well known. Here, zebrafish were exposed to 100 μg/L As, 300 μg/L 2,2-dichloroacetamide (DCAcAm), and their combination for 23 days. Then transcriptome profiles of cell populations in zebrafish liver were analyzed by single-cell RNA sequencing (scRNA-seq). A total of 13,563 cells were obtained, which were identified as hepatocytes, hepatic duct cells, endothelial cells and macrophages. Hepatocytes were the main target cell subtype of As and DCAcAm exposures. DCAcAm exposure induced higher toxicity in male hepatocytes, which specifically changed amino acid metabolism, response to hormone and cofactor metabolism. However, As exposure caused higher toxicity in female hepatocytes, which altered lipid metabolism, carbon metabolism, and peroxisome. Combined exposure to As and DCAcAm decreased toxicities in hepatocytes compared to each one alone. Female hepatocytes had higher tolerance to co-exposure of As and DCAcAm than male hepatocytes. Further, combined exposure to As and DCAcAm induced functional changes in macrophages similar to As alone groups, which mainly altered the transfer of sterol and cholesterol. Hepatic duct cells and endothelial cells were not influenced by exposures to As and DCAcAm. This study for the first time highlights the cell-specific combined responses of As and DCAcAm in zebrafish liver, which provide useful information for their health risk assessment in a co-exposure environment.

Arsenic-fluoride co-exposure induced endoplasmic reticulum stress resulting in apoptosis in rat heart and H9c2 cells

Exposure to arsenic (As) or fluoride (F) has been shown to cause cardiovascular disease (CVDs). However, evidence about the effects of co-exposure to As and F on myocardium and their mechanisms remain scarce. Our aim was to fill the gap by establishing rat and H9c2 cell exposure models. We determined the effects of As and/or F exposure on the survival rate, apoptosis rate, morphology and ultrastructure of H9c2 cells; in addition, we tested the related genes and proteins of endoplasmic reticulum stress (ERS) and apoptosis in H9c2 cells and rat heart tissues. The results showed that As and/or F exposure induced early apoptosis of H9c2 cells and caused endoplasmic reticulum expansion. Additionally, the mRNA and protein expression levels of GRP78, PERK and CHOP in H9c2 cells were higher in the exposure groups than in the control group, and could be inhibited by 4-PBA. Furthermore, we found that As and/or F exposure increased the expression level of GRP78 in rat heart tissues, but interestingly, the expression level of CHOP protein was increased in the F and As groups, while significantly decreased in the co-exposure group. Overall, our results suggested that ERS-induced apoptosis was involved in the damage of myocardium by As and/or F exposure. In addition, factorial analysis results showed that As and F mainly play antagonistic roles in inducing myocardial injury, initiating ERS and apoptosis after exposure.

The Efficacy of Fecal Microbiota Transplantation in Experimental Autoimmune Encephalomyelitis: Transcriptome and Gut Microbiota Profiling

Objective

To study the protective effect of fecal microbiota transplantation (FMT) on experimental autoimmune encephalomyelitis (EAE) and reveal its potential intestinal microflora-dependent mechanism through analyses of the intestinal microbiota and spinal cord transcriptome in mice.

Method

We measured the severity of disease by clinical EAE scores and H&E staining. Gut microbiota alteration in the gut and differentially expressed genes (DEGs) in the spinal cord were analyzed through 16S rRNA and transcriptome sequencing. Finally, we analyzed associations between the relative abundance of intestinal microbiota constituents and DEGs.

Results

We observed that clinical EAE scores were lower in the EAE+FMT group than in the EAE group. Meanwhile, mice in the EAE+FMT group also had a lower number of infiltrating cells. The results of 16S rRNA sequence analysis showed that FMT increased the relative abundance of Firmicutes and Proteobacteria and reduced the abundance of Bacteroides and Actinobacteria. Meanwhile, FMT could modulate gut microbiota balance, especially via increasing the relative abundance of g_Adlercreutzia, g_Sutterella, g_Prevotella_9, and g_Tyzzerella_3 and decreasing the relative abundance of g_Turicibacter. Next, we analyzed the transcriptome of mouse spinal cord tissue and found that 1476 genes were differentially expressed between the EAE and FMT groups. The analysis of these genes showed that FMT mainly participated in the inflammatory response. Correlation analysis between gut microbes and transcriptome revealed that the relative abundance of Adlercreutzia was correlated with the expression of inflammation-related genes negatively, including Casp6, IL1RL2 (IL-36R), IL-17RA, TNF, CCL3, CCR5, and CCL8, and correlated with the expression of neuroprotection-related genes positively, including Snap25, Edil3, Nrn1, Cpeb3, and Gpr37.

Conclusion

Altogether, FMT may selectively regulate gene expression to improve inflammation and maintain the stability of the intestinal environment in a gut microbiota-dependent manner.