Intestinal Microbiota Metabolism and Atherosclerosis

Three-Dimensional Scaffolds for Intestinal Cell Culture: Fabrication, Utilization, and Prospects

The intestine is a visceral organ that integrates absorption, metabolism, and immunity, which is vulnerable to external stimulus. Researchers in the fields such as food science, immunology, and pharmacology have committed to developing appropriate in vitro intestinal cell models to study the intestinal absorption and metabolism mechanisms of various nutrients and drugs, or pathogenesis of intestinal diseases. In the past three decades, the intestinal cell models have undergone a significant transformation from conventional two-dimensional cultures to three-dimensional (3D) systems, and the achievements of 3D cell culture have been greatly contributed by the fabrication of different scaffolds. In this review, we first introduce the developing trend of existing intestinal models. Then, four types of scaffolds, including Transwell, hydrogel, tubular scaffolds, and intestine-on-a-chip, are discussed for their 3D structure, composition, advantages, and limitations in the establishment of intestinal cell models. Excitingly, some of the in vitro intestinal cell models based on these scaffolds could successfully mimic the 3D structure, microenvironment, mechanical peristalsis, fluid system, signaling gradients, or other important aspects of the original human intestine. Furthermore, we discuss the potential applications of the intestinal cell models in drug screening, disease modeling, and even regenerative repair of intestinal tissues. This review presents an overview of state-of-the-art scaffold-based cell models within the context of intestines, and highlights their major advances and applications contributing to a better knowledge of intestinal diseases. Impact statement The intestine tract is crucial in the absorption and metabolism of nutrients and drugs, as well as immune responses against external pathogens or antigens in a complex microenvironment. The appropriate experimental cell model in vitro is needed for in-depth studies of intestines, due to the limitation of animal models in dynamic control and real-time assessment of key intestinal physiological and pathological processes, as well as the "R" principles in laboratory animal experiments. Three-dimensional (3D) scaffold-based cell cultivation has become a developing tendency because of the superior cell proliferation and differentiation and more physiologically relevant environment supported by the customized 3D scaffolds. In this review, we summarize four types of up-to-date 3D cell culture scaffolds fabricated by various materials and techniques for a better recapitulation of some essential physiological and functional characteristics of original intestines compared to conventional cell models. These emerging 3D intestinal models have shown promising results in not only evaluating the pharmacokinetic characteristics, security, and effectiveness of drugs, but also studying the pathological mechanisms of intestinal diseases at cellular and molecular levels. Importantly, the weakness of the representative 3D models for intestines is also discussed.

Gut microbiota and microbiota-derived metabolites in cardiovascular diseases

ABSTRACT

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

Effects of Unconventional Work and Shift Work on the Human Gut Microbiota and the Potential of Probiotics to Restore Dysbiosis

The work environment is a factor that can significantly influence the composition and functionality of the gut microbiota of workers, in many cases leading to gut dysbiosis that will result in serious health problems. The aim of this paper was to provide a compilation of the different studies that have examined the influence of jobs with unconventional work schedules and environments on the gut microbiota of workers performing such work. As a possible solution, probiotic supplements, via modulation of the gut microbiota, can moderate the effects of sleep disturbance on the immune system, as well as restore the dysbiosis produced. Rotating shift work has been found to be associated with an increase in the risk of various metabolic diseases, such as obesity, metabolic syndrome, and type 2 diabetes. Sleep disturbance or lack of sleep due to night work is also associated with metabolic diseases. In addition, sleep disturbance induces a stress response, both physiologically and psychologically, and disrupts the healthy functioning of the gut microbiota, thus triggering an inflammatory state. Other workers, including military, healthcare, or metallurgy workers, as well as livestock farmers or long-travel seamen, work in environments and schedules that can significantly affect their gut microbiota.

The preventive effect of Glycyrrhiza polysaccharide on lipopolysaccharide-induced acute colitis in mice by modulating gut microbial communities

Acute colitis is characterised by an unpredictable onset and causes intestinal flora imbalance together with microbial migration, which leads to complex parenteral diseases. Dexamethasone, a classic drug, has side effects, so it is necessary to use natural products without side effects to prevent enteritis. Glycyrrhiza polysaccharide (GPS) is an α-d-pyranoid polysaccharide with anti-inflammatory effects; however, its anti-inflammatory mechanism in the colon remains unknown. This study investigated whether GPS reduces the lipopolysaccharide (LPS)-induced inflammatory response in acute colitis. The results revealed that GPS attenuated the upregulation of tumour necrosis factor-α, interleukin (IL)-1β, and IL-6 in the serum and colon tissues and significantly reduced the malondialdehyde content in colon tissues. In addition, the 400 mg/kg GPS group showed higher relative expressions of occludin, claudin-1, and zona occludens-1 in colon tissues and lower concentrations of diamine oxidase, D-lactate, and endotoxin in the serum than the LPS group did, indicating that GPS improved the physical and chemical barrier functions of colon tissues. GPS increased the abundance of beneficial bacteria, such as Lactobacillus, Bacteroides, and Akkermansia, whereas pathogenic bacteria, such as Oscillospira and Ruminococcus were inhibited. Our findings indicate that GPS can effectively prevent LPS-induced acute colitis and exert beneficial effects on the intestinal health.

Microbiota-related metabolites fueling the understanding of ischemic heart disease

Up-to-date knowledge of gut microbial taxa associated with ischemic heart disease (IHD). Microbial metabolites for mechanistic dissection of IHD pathology. Microbiome-based therapies in IHD prevention and treatment.

Effects of intestinal bacteria on cardiovascular disease

In the long process of human evolution, the Intestinal Bacteria has become intimately related to human health, producing many metabolites in the intestines that can affect cardiovascular disease. Today, the incidence of cardiovascular disease is rising, its treatment is becoming increasingly important, and new therapeutic targets are needed. Here we describe the effects of trimethylamine oxide (TMAO), lipid metabolism, phenolic compounds, indole sulfate (IS), oleuropein (OL), and hydroxytyrosol (HT) on atherosclerosis, heart failure, hypertension, and other cardiovascular diseases, as well as their mechanism of action. This study provides new ideas, new methods, and new directions for the treatment of cardiovascular disease.

Manipulation of Gut Microbiota as a Key Target for Crohn's Disease

Crohn's disease (CD) is an inflammatory bowel disease (IBD) sub-type characterized by transmural chronic inflammation of the gastrointestinal tract. Research indicates a complex CD etiology involving genetic predisposition and immune dysregulation in response to environmental triggers. The chronic mucosal inflammation has been associated with a dysregulated state, or dysbiosis, of the gut microbiome (bacteria), mycobiome (fungi), virome (bacteriophages and viruses), and archeaome (archaea) further affecting the interkingdom syntrophic relationships and host metabolism. Microbiota dysbiosis in CD is largely described by an increase in facultative anaerobic pathobionts at the expense of strict anaerobic Firmicutes, such as Faecalibacterium prausnitzii. In the mycobiome, reduced fungal diversity and fungal-bacteria interactions, along with a significantly increased abundance of Candida spp. and a decrease in Saccharomyces cerevisiae are well documented. Virome analysis also indicates a significant decrease in phage diversity, but an overall increase in phages infecting bacterial groups associated with intestinal inflammation. Finally, an increase in methanogenic archaea such as Methanosphaera stadtmanae exhibits high immunogenic potential and is associated with CD etiology. Common anti-inflammatory medications used in CD management (amino-salicylates, immunomodulators, and biologics) could also directly or indirectly affect the gut microbiome in CD. Other medications often used concomitantly in IBD, such as antibiotics, antidepressants, oral contraceptives, opioids, and proton pump inhibitors, have shown to alter the gut microbiota and account for increased susceptibility to disease onset or worsening of disease progression. In contrast, some environmental modifications through alternative therapies including fecal microbiota transplant (FMT), diet and dietary supplements with prebiotics, probiotics, and synbiotics have shown potential protective effects by reversing microbiota dysbiosis or by directly promoting beneficial microbes, together with minimal long-term adverse effects. In this review, we discuss the different approaches to modulating the global consortium of bacteria, fungi, viruses, and archaea in patients with CD through therapies that include antibiotics, probiotics, prebiotics, synbiotics, personalized diets, and FMT. We hope to provide evidence to encourage clinicians and researchers to incorporate these therapies into CD treatment options, along with making them aware of the limitations of these therapies, and indicate where more research is needed.

Targeting Trimethylamine N-Oxide: A New Therapeutic Strategy for Alleviating Atherosclerosis

Atherosclerosis (AS) is one of the most common cardiovascular diseases (CVDs), and there is currently no effective drug to reverse its pathogenesis. Trimethylamine N-oxide (TMAO) is a metabolite of the gut flora with the potential to act as a new risk factor for CVD. Many studies have shown that TMAO is involved in the occurrence and development of atherosclerotic diseases through various mechanisms; however, the targeted therapy for TMAO remains controversial. This article summarizes the vital progress made in relation to evaluations on TMAO and AS in recent years and highlights novel probable approaches for the prevention and treatment of AS.

Influence of different regimens of volumetric therapy on perioperative intestinal flora in the surgical patients with pancreas tumor, a randomized controlled trial study

Background

It is not clear whether the perioperative intestinal microenvironment of patients undergoing pancreatic tumor surgery is affected by intraoperative fluid therapy.

Method

Fifty-eight patients who underwent a confined excision of pancreas mass at this center were enrolled. The patients were grouped according to the random number table in these two groups: the liberal fluid infusion (LFI) group and the goal-directed fluid therapy (GDFT) group. Perioperative anesthesia management was carried out by the same team of anesthesiologists according to a preset anesthetic protocol. Fecal samples were collected twice: within 2 days before the surgery and at 6 to 8 days postoperatively. The collected fecal samples were sequenced through microbial diversity high-throughput 16 s-rDNA; and the differential changes of intestinal flora were analyzed.

Results

Main components of flora in the sample were significantly different between LFI and GDFT groups. As shown by the difference in species, in GDFT group, more constituent bacteria participated in the metabolism inside human body and the restoration of coagulation function, including: prevotella, roseburia, lachnospiracea, dialister and clostridium (P < 0.05); in LFI group, more constituent bacteria were opportunistic pathogenic bacteria, including: enterococcus, pseudomonas aeruginosa, and acinetobacter baumannii (P < 0.05).

Conclusion

For surgical patients with pancreas tumor, there are significant differences of intestinal flora in diversity between GDFT and LFI. GDFT seems to play a more important role in protection and restoration of intestinal flora.

Clinical trial registration

ChiCTR2000035187.

Danggui Buxue Decoction Ameliorates Idiopathic Pulmonary Fibrosis through MicroRNA and Messenger RNA Regulatory Network

OBJECTIVE

To develop a putative microRNA (miRNA) and messenger RNA (mRNA) regulatory network of Danggui Buxue decoction's (DGBXD) amelioration of idiopathic pulmonary fibrosis (IPF).

METHODS

The Gene Expression Omnibus (GEO) database was used to identify differentially expressed miRNAs (DE-miRNAs) and differentially expressed mRNAs (DE-mRNAs). Using miRNet, the predicted target genes of identified DE-miRNAs were estimated, and then the target genes of DE-miRNAs in IPF were comprehensively examined. The Enrichr database was used to conduct functional enrichment and pathway enrichment. Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) was employed to obtain the target genes of DGBXD as well as active compounds. A putative miRNA-mRNA regulatory network of DGBXD acting on IPF was developed by intersecting the target genes of DGBXD with the DE-miRNA target genes in IPF. A bleomycin-induced mouse model was established and used to perform histopathology as well as real-time quantitative polymerase chain reaction (qRT-PCR) analyses of some miRNA-mRNA pairs.

RESULTS

Fourteen upmodulated DE-miRNAs and six downmodulated DE-miRNAs were screened. The downstream target genes of upmodulated and downmodulated DE-miRNAs were predicted. Subsequently, 1160 upmodulated DE-mRNAs and 1427 downmodulated DE-mRNAs were identified. Then, target genes of DE-miRNAs comprising 49 downmodulated and 53 upmodulated target genes were further screened to perform functional enrichment and pathway enrichment analyses. Subsequently, 196 target genes of DGBXD were obtained from TCMSP, with six downregulated target genes and six upregulated target genes of DGBXD acting on IPF being identified. A promising miRNA-mRNA regulatory network of DGBXD acting on IPF was developed in this study. Moreover, mir-493 together with its target gene Olr1 and mir-338 together with Hif1a were further validated by qRT-PCR.

CONCLUSION

This study proposed detailed possible processes of miRNA-mRNA modulatory axis in IPF and constructed a prospective IPF-related miRNA-mRNA modulatory network with the aim of alleviating IPF with DGBXD.

Nutraceuticals in the Modulation of the Intestinal Microbiota: Current Status and Future Directions

Pharmaceutical interest in the human intestinal microbiota has increased considerably, because of the increasing number of studies linking the human intestinal microbial ecology to an increasing number of non-communicable diseases. Many efforts at modulating the gut microbiota have been made using probiotics, prebiotics and recently postbiotics. However, there are other, still little-explored opportunities from a pharmaceutical point of view, which appear promising to obtain modifications of the microbiota structure and functions. This review summarizes all in vitro, in vivo and clinical studies demonstrating the possibility to positively modulate the intestinal microbiota by using probiotics, prebiotics, postbiotics, essential oils, fungus and officinal plants. For the future, clinical studies investigating the ability to impact the intestinal microbiota especially by using fungus, officinal and aromatic plants or their extracts are required. This knowledge could lead to effective microbiome modulations that might support the pharmacological therapy of most non-communicable diseases in a near future.

Pathobiological Relationship of Excessive Dietary Intake of Choline/L-Carnitine: A TMAO Precursor-Associated Aggravation in Heart Failure in Sarcopenic Patients

The microecological environment of the gastrointestinal tract is altered if there is an imbalance between the gut microbiota phylases, resulting in a variety of diseases. Moreover, progressive age not only slows down physical activity but also reduces the fat metabolism pathway, which may lead to a reduction in the variety of bacterial strains and bacteroidetes' abundance, promoting firmicutes and proteobacteria growth. As a result, dysbiosis reduces physiological adaptability, boosts inflammatory markers, generates ROS, and induces the destruction of free radical macromolecules, leading to sarcopenia in older patients. Research conducted at various levels indicates that the microbiota of the gut is involved in pathogenesis and can be considered as the causative agent of several cardiovascular diseases. Local and systematic inflammatory reactions are caused in patients with heart failure, as ischemia and edema are caused by splanchnic hypoperfusion and enable both bacterial metabolites and bacteria translocation to enter from an intestinal barrier, which is already weakened, to the blood circulation. Multiple diseases, such as HF, include healthy microbe-derived metabolites. These key findings demonstrate that the gut microbiota modulates the host's metabolism, either specifically or indirectly, by generating multiple metabolites. Currently, the real procedures that are an analogy to the symptoms in cardiac pathologies, such as cardiac mass dysfunctions and modifications, are investigated at a minimum level in older patients. Thus, the purpose of this review is to summarize the existing knowledge about a particular diet, including trimethylamine, which usually seems to be effective for the improvement of cardiac and skeletal muscle, such as choline and L-carnitine, which may aggravate the HF process in sarcopenic patients.

Effect of Differences in the Microbiome of Cyp17a1-Deficient Mice on Atherosclerotic Background

CYP17A1 is a cytochrome P450 enzyme that has 17-alpha-hydroxylase and C17,20-lyase activities. Cyp17a11 deficiency is associated with high body mass and visceral fat deposition in atherosclerotic female ApoE knockout (KO, d/d or -/-) mice. In the present study, we aimed to investigate the effects of diet and Cyp17a1 genotype on the gut microbiome. Female Cyp17a1 (d/d) × ApoE (d/d) (DKO) and ApoE (d/d) (controls) were fed either standard chow or a Western-type diet (WTD), and we demonstrated the effects of genetics and diet on the body mass of the mice and composition of their gut microbiome. We found a significantly lower alpha diversity after accounting for the ecological network structure in DKO mice and WTD-fed mice compared with chow-fed ApoE(d/d). Furthermore, we found a strong significant positive association of the Firmicutes vs. Bacteroidota ratio with body mass and the circulating total cholesterol and triglyceride concentrations of the mice when feeding the WTD, independent of the Cyp17a1 genotype. Further pathway enrichment and network analyses revealed a substantial effect of Cyp17a1 genotype on associated cardiovascular and obesity-related pathways involving aspartate and L-arginine. Future studies are required to validate these findings and further investigate the role of aspartate/L-arginine pathways in the obesity and body fat distribution in our mouse model.

Gut microbiota metabolites as integral mediators in cardiovascular diseases (Review)

Cardiovascular diseases (CVDs), such as atherosclerosis, hypertension, myocardial infarction and diabetic heart disease, are associated with high morbidity and mortality rates worldwide, and may also induce multiple organ failure in their later stages, greatly reducing the long-term survival of the patients. There are several causes of CVDs, but after nearly a decade of investigation, researchers have found that CVDs are usually accompanied by an imbalance of gut microbiota and a decreased abundance of flora. More importantly, the metabolites produced by intestinal flora, such as trimethylamine and trimethylamine N-oxide, bile acids, short-chain fatty acids and aromatic amino acids, exert different effects on the occurrence and development of CVDs, as observed in the relevant pathways in the cells, which may either promote or protect against CVD occurrence. It is known that changes in the intestinal flora following antibiotic administration, diet supplementation with probiotics, or exercise, can interfere with the composition of the intestinal flora and may represent an effective approach to preventing or treating CVDs. The focus of this review was the analysis of gut microbiota metabolites to elucidate their effects on CVDs and to identify the most cost-effective and beneficial methods for treating CVDs with minimal side effects.

Gut Microbiota, Atherosclerosis, and Therapeutic Targets

Several studies have gathered interest in the relationship between gut microbiota and atherosclerosis. Gut microbiota and its metabolites, such as trimethylamine-N-oxide, and gut dysbiosis play an important role in the development of atherosclerosis. Also, inflammation, derived by the intestinal tract, adds another mechanism through which the ecosystem of the human body affects the metabolic diseases and, furthermore, cardiovascular diseases. The scientific world should fixate the understanding of the exact physiologic and pathophysiologic mechanisms for atherogenesis by gut microbiota and through that, new ways for novel therapeutic targets will be available in the coming years. This review summarizes the latest data on this matter.

Probiotics maintain the intestinal microbiome homeostasis of the sailors during a long sea voyage

The challenging conditions encountered during long sea voyages increase the risk of health-threatening physiological and psychological stress for sailors compared with land-based workers. However, how the intestinal microbiota responds to a long sea voyage and whether there is a feasible approach for protecting gut health during sea voyage are still unexplored. Here, we designed a 30-d longitudinal study including a placebo group (n = 42) and a probiotic group (n = 40) and used shotgun metagenomic sequencing to explore the impacts of sea voyage on the intestinal microbiome of sailors. By comparing the intestinal microbiome of subjects in the placebo group at baseline (d 0) and at the end of the sea voyage (d 30), we observed an alteration in the intestinal microbiome during the long sea voyage based on the microbial structure; the results revealed an increase in the species Streptococcus gordonii and Klebsiella pneumoniae as well as a decrease in some functional features. However, the change in the microbial structure of sailors in the probiotic group between d 0 and d 30 was limited, which indicated a maintenance effect of probiotics on intestinal microbiome homeostasis. At the metagenomic strain level, a generally positive correlation was observed between probiotics and the strains belonging to Bifidobacterium longum and Bifidobacterium animalis, whereas a common negative correlation was observed between probiotics and Clostridium leptum; this result revealed the potential mechanism of maintaining intestinal microbiome homeostasis by probiotics. The present study provided a feasible approach for protecting gut health during a long sea voyage.

Gut Microbiota beyond Bacteria-Mycobiome, Virome, Archaeome, and Eukaryotic Parasites in IBD

The human microbiota is a diverse microbial ecosystem associated with many beneficial physiological functions as well as numerous disease etiologies. Dominated by bacteria, the microbiota also includes commensal populations of fungi, viruses, archaea, and protists. Unlike bacterial microbiota, which was extensively studied in the past two decades, these non-bacterial microorganisms, their functional roles, and their interaction with one another or with host immune system have not been as widely explored. This review covers the recent findings on the non-bacterial communities of the human gastrointestinal microbiota and their involvement in health and disease, with particular focus on the pathophysiology of inflammatory bowel disease.

Gut microbiota and cardiovascular disease: opportunities and challenges

Coronary artery disease (CAD) is the most common health problem worldwide and remains the leading cause of morbidity and mortality. Over the past decade, it has become clear that the inhabitants of our gut, the gut microbiota, play a vital role in human metabolism, immunity, and reactions to diseases, including CAD. Although correlations have been shown between CAD and the gut microbiota, demonstration of potential causal relationships is much more complex and challenging. In this review, we will discuss the potential direct and indirect causal roots between gut microbiota and CAD development via microbial metabolites and interaction with the immune system. Uncovering the causal relationship of gut microbiota and CAD development can lead to novel microbiome-based preventative and therapeutic interventions. However, an interdisciplinary approach is required to shed light on gut bacterial-mediated mechanisms (e.g., using advanced nanomedicine technologies and incorporation of demographic factors such as age, sex, and ethnicity) to enable efficacious and high-precision preventative and therapeutic strategies for CAD.

Early Programming of Adult Systemic Essential Hypertension

Cardiovascular diseases are being included in the study of developmental origins of health and disease (DOHaD) and essential systemic hypertension has also been added to this field. Epigenetic modifications are one of the main mechanisms leading to early programming of disease. Different environmental factors occurring during critical windows in the early stages of life may leave epigenetic cues, which may be involved in the programming of hypertension when individuals reach adulthood. Such environmental factors include pre-term birth, low weight at birth, altered programming of different organs such as the blood vessels and the kidney, and living in disadvantageous conditions in the programming of hypertension. Mechanisms behind these factors that impact on the programming include undernutrition, oxidative stress, inflammation, emotional stress, and changes in the microbiota. These factors and their underlying causes acting at the vascular level will be discussed in this paper. We also explore the establishment of epigenetic cues that may lead to hypertension at the vascular level such as DNA methylation, histone modifications (methylation and acetylation), and the role of microRNAs in the endothelial cells and blood vessel smooth muscle which participate in hypertension. Since epigenetic changes are reversible, the knowledge of this type of markers could be useful in the field of prevention, diagnosis or epigenetic drugs as a therapeutic approach to hypertension.

Microbial Profile and Genetic Polymorphism of Predominant Species in Some Traditional Fermented Seafoods of the Hainan Area in China

Fermented fish, fermented shrimp and fermented crab are traditionally prepared seafoods that are commonly consumed in the Hainan area in China. We studied the microbial diversity and metabolic pathways in traditional fermented seafoods using high-throughput sequencing technology, and based on our previous research, we also compared the differences between fermented seafood and fermented vegetables. The alpha diversity of fermented seafood was higher than that of fermented vegetables and attained the highest level in fermented shrimp. The dominant genera in fermented seafood were different from those of fermented vegetables. Furthermore, we analyzed the 16S rDNA gene polymorphisms (SNPs) of the same dominant species (Lactobacillus plantarum and Lactobacillus fermentum) in two fermented environments, which showed that most of the mutations occurred in fermented vegetables and that fermenting environment might be the major factor for these mutations. This research provides us with new insights into beneficial microbial resources in regard to microbial diversity and genetic polymorphisms and lays a foundation for the subsequent development and utilization of beneficial microorganisms.

The microbiome and inborn errors of metabolism: Why we should look carefully at their interplay?

Research into the influence of the microbiome on the human body has been shedding new light on diseases long known to be multifactorial, such as obesity, mood disorders, autism, and inflammatory bowel disease. Although inborn errors of metabolism (IEMs) are monogenic diseases, genotype alone is not enough to explain the wide phenotypic variability observed in patients with these conditions. Genetics and diet exert a strong influence on the microbiome, and diet is used (alone or as an adjuvant) in the treatment of many IEMs. This review will describe how the effects of the microbiome on the host can interfere with IEM phenotypes through interactions with organs such as the liver and brain, two of the structures most commonly affected by IEMs. The relationships between treatment strategies for some IEMs and the microbiome will also be addressed. Studies on the microbiome and its influence in individuals with IEMs are still incipient, but are of the utmost importance to elucidating the phenotypic variety observed in these conditions.

Lactobacillus plantarum HNU082-derived improvements in the intestinal microbiome prevent the development of hyperlipidaemia

Restricted by research techniques, the probiotic-derived changes in the microbiome and microbial metabolites correlated with the potential prevention of hyperlipidaemia have remained undiscovered. In the present research, a metagenomic approach was applied to describe Lactobacillus plantarum HNU082 consumption-derived changes in the intestinal microbiome and their correlation with the occurrence and development of hyperlipidaemia. Principal coordinate analysis based on UniFrac distances indicated that the intestinal microbiota was profoundly altered in the hyperlipidaemia group, and probiotic consumption regulated the bias in the intestinal microbial structure in hyperlipidaemia. Bifidobacterium, Lactobacillus, Akkermansia and Faecalibacterium were significantly increased in the probiotic group, and the genera Clostridium, Natranaerovirga and Odoribacter were significantly increased in the hyperlipidaemia group. Further analysis based on metabolic pathways revealed that pyruvate metabolism, glycerolipid metabolism, propanoate metabolism, and fatty acid biosynthesis were enriched in the probiotic and control groups. In contrast, the pathways of secondary bile acid and lipopolysaccharide biosynthesis were enriched in the hyperlipidaemia group. Finally, we constructed a network to better explain the potential mechanism of hyperlipidaemia prevention. The present basic research will promote our understanding of the probiotic action mechanism in hyperlipidaemia therapy and provide new insight into the design and application of probiotic-containing functional foods.

Evolving targets for the treatment of atherosclerosis

Atherosclerosis is a progressive disease of large arteries and a leading cause of cardiovascular diseases and stroke. Chronic inflammation, aberrant immune response, and disturbances to key enzymes involved with lipid metabolism are characteristic features of atherosclerosis. Apart from targeting the derangements in lipid metabolism, therapeutic modulation to regulate chronic inflammation and the immune system response may prove to be very promising strategies in the management of atherosclerosis. In recent years, various targets have been studied for the treatment of atherosclerosis. PCSK9, a serine protease, actively targets the LDL-R and causes lysosomal degradation, which leads to excessive accumulation of LDL-C. Regulatory T cells (Tregs) and Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) affects the adaptive and innate immune response, respectively, and thus, therapeutic intervention of either of these targets would directly modulate disease progression. Advanced atherosclerotic lesions are characterized by an accumulation of apoptotic cells. Cluster of differentiation-47 (CD47), an anti-phagocytic known as the "don't eat me" signaling molecule, inhibits efferocytosis, which causes accumulation of cell debris in plaque. ADAMTS and Notch signaling potentially affect the formation of neointima by modulation of extracellular matrix components such as macrophages and vascular smooth muscle cells. This review provides insights on the molecular targets for therapeutic intervention of atherosclerosis, their effect at various stages of atherosclerosis development, and the therapies that have been designed and currently being evaluated in clinical trials.

Gut Microbiota Metabolites and Risk of Major Adverse Cardiovascular Disease Events and Death: A Systematic Review and Meta-Analysis of Prospective Studies

BACKGROUND

Gut microbial metabolites have been implicated as novel risk factors for cardiovascular events and premature death. The strength and consistency of associations between blood concentrations of the gut microbial metabolites, trimethylamine-N-oxide (TMAO) and its precursors, with major adverse cardiovascular events (MACE) or death have not been comprehensively assessed. We quantified associations of blood concentrations of TMAO and its precursors with risks of MACE and mortality.

METHODS AND RESULTS

PubMed and Embase databases were searched up, and a total of 19 prospective studies from 16 publications (n=19 256, including 3315 incident cases) with quantitative estimates of the associations of TMAO with the development of MACE or death were included in our main analysis. Multivariate-adjusted relative risks (RRs) were used when these were available. Elevated concentrations of TMAO were associated with a pooled RR of 1.62 (95% CI, 1.45, 1.80; P_{heterogeneity}=0.2; I²=23.5%) for MACE compared with low TMAO levels, and 1 study of black participants influenced the heterogeneity of the association. After excluding the data of blacks, the RRs were not different according to body mass index, prevalence of diabetes mellitus, history of cardiovascular diseases, and kidney dysfunction. Furthermore, elevated TMAO concentrations were associated with a pooled RR of 1.63 (1.36, 1.95) for all-cause mortality. Individuals with elevated concentrations of TMAO precursors (l-carnitine, choline, or betaine) had an approximately 1.3 to 1.4 times higher risk for MACE compared to those with low concentrations.

CONCLUSIONS

Elevated concentrations of TMAO and its precursors were associated with increased risks of MACE and all-cause mortality independently of traditional risk factors.

Trimethylamine N-oxide prime NLRP3 inflammasome via inhibiting ATG16L1-induced autophagy in colonic epithelial cells

Recently, the intricate relationship between Trimethylamine N-oxide (TMAO) and inflammatory bowel disease (IBD) is of growing interest. The NLRP3 inflammasome plays crucial roles in gut homeostasis and determining the severity of inflammation in IBD, however, the precise roles of the NLRP3 inflammasome in IBD are still debated. ATG16L1 mediates the cellular degradative process of autophagy and is considered a critical regulator of inflammation based on its genetic association with IBD. Whether TMAO prime NLRP3 inflammasome via ATG16L1-induced autophagy remains unclear. This study observed the expression of ATG16L1, LC3-II and p62 and activation of NLRP3 inflammasome stimulated by TMAO in fetal human colon cells (FHCs), aiming to elucidate the mechanism by which the TMAO may contribute to colonic epithelial inflammation. Our results demonstrated that TMAO significantly inhibited ATG16L1, LC3-II and p62 expression, and triggered the activated NLRP3 inflammasome and production of ROS in a dose- and time-dependent manner. Furthermore, TMAO-mediated effects were observably reversed by over-expression ATG16L1 and siRNA-mediated knockdown NLRP3.The present results support the hypothesis that TMAO may be involved in the pathogenesis of IBD by impacting ATG16L1-induced autophagy and activating NLRP3 inflammasome, suggesting a potential therapeutic targets for the treatment of IBD and TMAO-associated complications.