Trimethylamine-N-Oxide Promotes Vascular Calcification Through Activation of NLRP3 (Nucleotide-Binding Domain, Leucine-Rich-Containing Family, Pyrin Domain-Containing-3) Inflammasome and NF-κB (Nuclear Factor κB) Signals

The serum levels of gasdermin D in uremic patients and its relationship with the prognosis: a prospective observational cohort study

OBJECTIVE

This study aimed to explore the serum levels of gasdermin D (GSDMD) in uremic (end-stage kidney disease, ESKD) patients and their correlation with vascular calcification (VC) and clinical results.

METHODS

This prospective observational cohort study enrolled 213 ESKD patients who were undergoing regular maintenance hemodialysis (MHD) for > 3 months in our hospital from August 2019 to July 2022. The abdominal aortic calcification score (AACS) was used to assess the VC condition of patients with ESKD. Serum GSDMD, caspase-1, interleukin (IL)-6, IL-1β, IL-18 and C-reactive protein (CRP) levels were measured using enzyme-linked immunosorbent assay (ELISA). Demographic and clinical data were obtained. All patients were followed up for 1 year, and patients with major adverse cardiovascular events (MACE) were defined as having a poor prognosis. All data used SPSS 26.0 to statistical analyses.

RESULTS

The serum total cholesterol (TC) levels of patients in the AACS > 4 group were significantly elevated compared with those in the AACS ≤ 4 group. In addition, ESKD patients with an AACS > 4 had significantly higher serum levels of GSDMD, caspase-1, IL-6, IL-18 and IL-1β. Moreover, Pearson's analysis supported a positive correlation between GSDMD and caspase-1, IL-6, and IL-1β. In addition, we found that GSDMD levels were positively correlated with the clinical data (AACS scores and serum TC levels) of patients with ERSD. Additionally, ROC curves showed that the serum levels of GSDMD could be a potential predictive biomarker of moderate/severe VC and prognosis in patients with ESKD. Finally, the results of logistic regression indicated that GSDMD and AACS scores were risk factors for poor prognosis in patients with ESKD.

CONCLUSION

Serum GSDMD levels were remarkably elevated in patients with ESKD with moderate/severe calcification. In addition, serum levels of GSDMD could be a potential predictive biomarker of moderate/severe VC and prognosis in patients with ESKD.

Let food be your medicine - dietary fiber

Dietary fiber (DF) cannot be digested and absorbed by the digestive tract, nor can it provide the energy needed to be burned for metabolic activities. Therefore, from the 1950s to the 1980s, DF received little attention in nutrition studies. With in-depth research and developments in global nutrition, people have gradually paid attention to the fact that DF occupies an essential position in the structure of nutrition, and it can ensure the healthy development of human beings. As early as 390 B.C., the ancient Greek physician Hippocrates proposed, "Let your food be your medicine, and your medicine be your food". This concept has been more systematically validated in modern scientific research, with numerous epidemiological studies showing that the dietary intake of DF-rich foods such as whole grains, root vegetables, legumes, and fruits has the potential to regulate the balance of the gut microbiota and thereby prevent diseases. However, the crosstalk between different types of DF and the gut microbiota is quite complex, and the effects on the organism vary. In this paper, we discuss research on DF and the gut microbiota and related diseases, aiming to understand the relationship between all three better and provide a reference basis for the risk reduction of related diseases.

Multi-metabolomics and intestine microbiome analysis: YZC extract ameliorates septic-ALI by modulating intestine microbiota to reduce TMAO/NLRP3 signaling

BACKGROUND

Sepsis causes inflammation in response to infection, often leading to acute lung injury (ALI). Yazhicao (Commelina communis L., YZC) is widely distributed in the global tropics and has good anti-respiratory inflammatory activity; however, the protection of YZC against septic-ALI has not been established.

PURPOSE

The role of YZC in septic-ALI will be investigated in this study.

METHODS AND RESULTS

In this study, YZC was shown to inhibit excessive inflammation and alleviate septic-ALI. Network pharmacology predicts that Quercetin, Acacetin and Diosmetin have the potential to serve as the pharmacological substance basis of YZC in alleviating septic-ALI. The metabolomics results indicated that YZC could improve the metabolic disorders caused by septic-ALI, which were mostly concerned with energy metabolism and amino acid metabolism, with Trimethylamine (TMA)/Trimethylamine N-oxide (TMAO) being potential small molecule metabolic markers for the clinical diagnosis and treatment of septic-ALI. YZC inhibits the initiation and progression of septic-ALI by controlling the TMA/TMAO metabolites. Our results also suggest that YZC protects the intestinal barrier from damage. Furthermore, our research indicated that YZC reduces TMAO synthesis by inhibiting TMA production through remodeling the intestine microbiota. We investigated the mechanism of YZC-mediated protection against septic-ALI and showed that YZC reduced the expression of proteins associated with NLRP3 inflammatory vesicles in the lung by inhibiting the expression of NF-κB.

CONCLUSION

These results show that YZC inhibits the NF-κB/NLRP3 signaling pathway by regulating metabolic and intestinal flora disorders in septic-ALI mice to reduce TMAO synthesis. This study presents a theoretical groundwork for the advancement of novel medications and clinical use of YZC to enhance septic-ALI and furnishes a theoretical rationale for regulating intestinal microbiota as a therapeutic instrument to treat sepsis and septic-ALI.

Systemic impacts of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) on heart, muscle, and kidney related diseases

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease (NAFLD), is the most common liver disorder worldwide, with an estimated global prevalence of more than 31%. Metabolic dysfunction-associated steatohepatitis (MASH), formerly known as non-alcoholic steatohepatitis (NASH), is a progressive form of MASLD characterized by hepatic steatosis, inflammation, and fibrosis. This review aims to provide a comprehensive analysis of the extrahepatic manifestations of MASH, focusing on chronic diseases related to the cardiovascular, muscular, and renal systems. A systematic review of published studies and literature was conducted to summarize the findings related to the systemic impacts of MASLD and MASH. The review focused on the association of MASLD and MASH with metabolic comorbidities, cardiovascular mortality, sarcopenia, and chronic kidney disease. Mechanistic insights into the concept of lipotoxic inflammatory "spill over" from the MASH-affected liver were also explored. MASLD and MASH are highly associated (50%-80%) with other metabolic comorbidities such as impaired insulin response, type 2 diabetes, dyslipidemia, hypertriglyceridemia, and hypertension. Furthermore, more than 90% of obese patients with type 2 diabetes have MASH. Data suggest that in middle-aged individuals (especially those aged 45-54), MASLD is an independent risk factor for cardiovascular mortality, sarcopenia, and chronic kidney disease. The concept of lipotoxic inflammatory "spill over" from the MASH-affected liver plays a crucial role in mediating the systemic pathological effects observed. Understanding the multifaceted impact of MASH on the heart, muscle, and kidney is crucial for early detection and risk stratification. This knowledge is also timely for implementing comprehensive disease management strategies addressing multi-organ involvement in MASH pathogenesis.

TMAO Impairs Mouse Aortic Vasodilation by Inhibiting TRPV4 Channels in Endothelial Cells

Trimethylamine oxide (TMAO) is an intestinal flora metabolite associated with risk of cardiovascular diseases. Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable ion channel that is essential for vasodilation and endothelial function. Currently, there are few studies on the effect of TMAO on TRPV4 channels. In the present study, Ca2+ imaging of vascular tissue showed that TMAO inhibited TRPV4-mediated Ca2+ influx into aortic endothelial cells in a dose-dependent manner. Furthermore, a whole-cell patch clamp assay showed that TMAO blocked TRPV4-mediated cation currents. Notably, results of aortic vascular tension measurement showed that TMAO impaired endothelium-dependent vasodilation in mouse aortic vessels through the TRPV4-NO pathway. Our results indicated that TMAO inhibited Ca2+ entry in endothelial cells and impaired vasodilation through the TRPV4-NO pathway in mice. These results provide scientific evidence for novel pathogenic mechanisms underlying the role of TMAO in cardiovascular disease.

Multi-omics analysis of kidney tissue metabolome and proteome reveals the protective effect of sheep milk against adenine-induced chronic kidney disease in mice

Chronic kidney disease (CKD) is characterized by impaired renal function and is associated with inflammation, oxidative stress, and fibrosis. Sheep milk contains several bioactive molecules with protective effects against inflammation and oxidative stress. In the current study, we investigated the potential renoprotective effects of sheep milk and the associated mechanisms of action in an adenine-induced CKD murine model. Sheep milk delayed renal chronic inflammation (e.g., significant reduction in levels of inflammatory factors Vcam1, Icam1, Il6, and Tnfa), fibrosis (significant reduction in levels of fibrosis factors Col1a1, Fn1, and Tgfb), oxidative stress (significant increase in levels of antioxidants and decrease in oxidative markers), mineral disorders, and renal injury in adenine-treated mice (e.g. reduced levels of kidney injury markers NGAL and KIM-1). The combined proteomics and metabolomics analyses showed that sheep milk may affect the metabolic processes of several compounds, including proteins, lipids, minerals, and hormones in mice with adenine-induced chronic kidney disease. In addition, it may regulate the expression of fibrosis-related factors and inflammatory factors through the JAK1/STAT3/HIF-1α signaling pathway, thus exerting its renoprotective effects. Therefore, sheep milk may be beneficial for patients with CKD and should be evaluated in preclinical and clinical studies.

Relationship between arginine methylation and vascular calcification

In patients on maintenance hemodialysis (MHD), vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD), which is the primary cause of death in chronic kidney disease (CKD). The main component of VC in CKD is the vascular smooth muscle cells (VSMCs). VC is an ordered, dynamic activity. Under the stresses of oxidative stress and calcium-‑phosphorus imbalance, VSMCs undergo osteogenic phenotypic transdifferentiation, which promotes the formation of VC. In addition to traditional epigenetics like RNA and DNA control, post-translational modifications have been discovered to be involved in the regulation of VC in recent years. It has been reported that the process of osteoblast differentiation is impacted by catalytic histone or non-histone arginine methylation. Its function in the osteogenic process is comparable to that of VC. Thus, we propose that arginine methylation regulates VC via many signaling pathways, including as NF-B, WNT, AKT/PI3K, TGF-/BMP/SMAD, and IL-6/STAT3. It might also regulate the VC-related calcification regulatory factors, oxidative stress, and endoplasmic reticulum stress. Consequently, we propose that arginine methylation regulates the calcification of the arteries and outline the regulatory mechanisms involved.

Regulated vascular smooth muscle cell death in vascular diseases

Regulated cell death (RCD) is a complex process that involves several cell types and plays a crucial role in vascular diseases. Vascular smooth muscle cells (VSMCs) are the predominant elements of the medial layer of blood vessels, and their regulated death contributes to the pathogenesis of vascular diseases. The types of regulated VSMC death include apoptosis, necroptosis, pyroptosis, ferroptosis, parthanatos, and autophagy-dependent cell death (ADCD). In this review, we summarize the current evidence of regulated VSMC death pathways in major vascular diseases, such as atherosclerosis, vascular calcification, aortic aneurysm and dissection, hypertension, pulmonary arterial hypertension, neointimal hyperplasia, and inherited vascular diseases. All forms of RCD constitute a single, coordinated cell death system in which one pathway can compensate for another during disease progression. Pharmacologically targeting RCD pathways has potential for slowing and reversing disease progression, but challenges remain. A better understanding of the role of regulated VSMC death in vascular diseases and the underlying mechanisms may lead to novel pharmacological developments and help clinicians address the residual cardiovascular risk in patients with cardiovascular diseases.

Pyroptosis of Vascular Smooth Muscle Cells as a Potential New Target for Preventing Vascular Diseases

Vascular remodeling is the adaptive response of the vessel wall to physiological and pathophysiological changes, closely linked to vascular diseases. Vascular smooth muscle cells (VSMCs) play a crucial role in this process. Pyroptosis, a form of programmed cell death characterized by excessive release of inflammatory factors, can cause phenotypic transformation of VSMCs, leading to their proliferation, migration, and calcification-all of which accelerate vascular remodeling. Inhibition of VSMC pyroptosis can delay this process. This review summarizes the impact of pyroptosis on VSMCs and the pathogenic role of VSMC pyroptosis in vascular remodeling. We also discuss inhibitors of key proteins in pyroptosis pathways and their effects on VSMC pyroptosis. These findings enhance our understanding of the pathogenesis of vascular remodeling and provide a foundation for the development of novel medications that target the control of VSMC pyroptosis as a potential treatment strategy for vascular diseases.

Applied physiology: gut microbiota and antimicrobial therapy

The gut microbiota plays an important role in maintaining human health and in the pathogenesis of several diseases. Antibiotics are among the most commonly prescribed drugs and have a significant impact on the structure and function of the gut microbiota. The understanding that a healthy gut microbiota prevents the development of many diseases has also led to its consideration as a potential therapeutic target. At the same time, any factor that alters the gut microbiota becomes important in this approach. Exercise and antibacterial therapy have a direct effect on the microbiota. The review reflects the current state of publications on the mechanisms of intestinal bacterial involvement in the pathogenesis of cardiovascular, metabolic, and neurodegenerative diseases. The physiological mechanisms of the influence of physical activity on the composition of the gut microbiota are considered. The mechanisms of the common interface between exercise and antibacterial therapy will be considered using the example of several socially important diseases. The aim of the study is to show the physiological relationship between the effects of exercise and antibiotics on the gut microbiota.

Role of gut microbiota in doxorubicin-induced cardiotoxicity: from pathogenesis to related interventions

Doxorubicin (DOX) is a broad-spectrum and highly efficient anticancer agent, but its clinical implication is limited by lethal cardiotoxicity. Growing evidences have shown that alterations in intestinal microbial composition and function, namely dysbiosis, are closely linked to the progression of DOX-induced cardiotoxicity (DIC) through regulating the gut-microbiota-heart (GMH) axis. The role of gut microbiota and its metabolites in DIC, however, is largely unelucidated. Our review will focus on the potential mechanism between gut microbiota dysbiosis and DIC, so as to provide novel insights into the pathophysiology of DIC. Furthermore, we summarize the underlying interventions of microbial-targeted therapeutics in DIC, encompassing dietary interventions, fecal microbiota transplantation (FMT), probiotics, antibiotics, and natural phytochemicals. Given the emergence of microbial investigation in DIC, finally we aim to point out a novel direction for future research and clinical intervention of DIC, which may be helpful for the DIC patients.

Research progress on the association between trimethylamine/trimethylamine-N-oxide and neurological disorders

Trimethylamine-N-oxide (TMAO) is a common intestinal metabolite. The Choline in the nutrient forms TMA under the action of the gut microbiota, which passes through the liver and eventually forms TMAO. Initial studies of TMAO focused on cardiovascular disease, but as research progressed, TAMO's effects were found to be multisystem and closely related to the development of neurological diseases. Intestinal tract is the organ with the largest concentration of bacteria in human body, and the composition and metabolism of gut microbiota affect human health. As a two-way communication axis connecting the central nervous system and the gastrointestinal tract, the brain-gut axis provides the structural basis for TMAO to play its role. This article will review the correlation between TMA/TMAO and neurological diseases in order to find new directions and new targets for the treatment of neurological diseases.

Oxidized phospholipid POVPC contributes to vascular calcification by triggering ferroptosis of vascular smooth muscle cells

Vascular calcification is an actively regulated biological process resembling bone formation, and osteogenic differentiation of vascular smooth muscle cells (VSMCs) plays a crucial role in this process. 1-Palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3-phosphocholine (POVPC), an oxidized phospholipid, is found in atherosclerotic plaques and has been shown to induce oxidative stress. However, the effects of POVPC on osteogenic differentiation and calcification of VSMCs have yet to be studied. In the present study, we investigated the role of POVPC in vascular calcification using in vitro and ex vivo models. POVPC increased mineralization of VSMCs and arterial rings, as shown by alizarin red staining. In addition, POVPC treatment increased expression of osteogenic markers Runx2 and BMP2, indicating that POVPC promotes osteogenic transition of VSMCs. Moreover, POVPC increased oxidative stress and impaired mitochondria function of VSMCs, as shown by increased ROS levels, impairment of mitochondrial membrane potential, and decreased ATP levels. Notably, ferroptosis triggered by POVPC was confirmed by increased levels of intracellular ROS, lipid ROS, and MDA, which were decreased by ferrostatin-1, a ferroptosis inhibitor. Furthermore, ferrostatin-1 attenuated POVPC-induced calcification of VSMCs. Taken together, our study for the first time demonstrates that POVPC promotes vascular calcification via activation of VSMC ferroptosis. Reducing the levels of POVPC or inhibiting ferroptosis might provide a novel strategy to treat vascular calcification.

Microbiota metabolites in bone: Shaping health and Confronting disease

The intricate interplay between the gut microbiota and bone health has become increasingly recognized as a fundamental determinant of skeletal well-being. Microbiota-derived metabolites play a crucial role in dynamic interaction, specifically in bone homeostasis. In this sense, short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate, indirectly promote bone formation by regulating insulin-like growth factor-1 (IGF-1). Trimethylamine N-oxide (TMAO) has been found to increase the expression of osteoblast genes, such as Runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein-2 (BMP2), thus enhancing osteogenic differentiation and bone quality through BMP/SMADs and Wnt signaling pathways. Remarkably, in the context of bone infections, the role of microbiota metabolites in immune modulation and host defense mechanisms potentially affects susceptibility to infections such as osteomyelitis. Furthermore, ongoing research elucidates the precise mechanisms through which microbiota-derived metabolites influence bone cells, such as osteoblasts and osteoclasts. Understanding the multifaceted influence of microbiota metabolites on bone, from regulating homeostasis to modulating susceptibility to infections, has the potential to revolutionize our approach to bone health and disease management. This review offers a comprehensive exploration of this evolving field, providing a holistic perspective on the impact of microbiota metabolites on bone health and diseases.

Cardiovascular Consequences of Uremic Metabolites: an Overview of the Involved Signaling Pathways

The crosstalk of the heart with distant organs such as the lung, liver, gut, and kidney has been intensively approached lately. The kidney is involved in (1) the production of systemic relevant products, such as renin, as part of the most essential vasoregulatory system of the human body, and (2) in the clearance of metabolites with systemic and organ effects. Metabolic residue accumulation during kidney dysfunction is known to determine cardiovascular pathologies such as endothelial activation/dysfunction, atherosclerosis, cardiomyocyte apoptosis, cardiac fibrosis, and vascular and valvular calcification, leading to hypertension, arrhythmias, myocardial infarction, and cardiomyopathies. However, this review offers an overview of the uremic metabolites and details their signaling pathways involved in cardiorenal syndrome and the development of heart failure. A holistic view of the metabolites, but more importantly, an exhaustive crosstalk of their known signaling pathways, is important for depicting new therapeutic strategies in the cardiovascular field.

Biomolecular Actions by Intestinal Endotoxemia in Metabolic Syndrome

Metabolic syndrome (MetS) is a combination of metabolic disorders that concurrently act as factors promoting systemic pathologies such as atherosclerosis or diabetes mellitus. It is now believed to encompass six main interacting conditions: visceral fat, imbalance of lipids (dyslipidemia), hypertension, insulin resistance (with or without impairing both glucose tolerance and fasting blood sugar), and inflammation. In the last 10 years, there has been a progressive interest through scientific research investigations conducted in the field of metabolomics, confirming a trend to evaluate the role of the metabolome, particularly the intestinal one. The intestinal microbiota (IM) is crucial due to the diversity of microorganisms and their abundance. Consequently, IM dysbiosis and its derivate toxic metabolites have been correlated with MetS. By intervening in these two factors (dysbiosis and consequently the metabolome), we can potentially prevent or slow down the clinical effects of the MetS process. This, in turn, may mitigate dysregulations of intestinal microbiota axes, such as the lung axis, thereby potentially alleviating the negative impact on respiratory pathology, such as the chronic obstructive pulmonary disease. However, the biomolecular mechanisms through which the IM influences the host's metabolism via a dysbiosis metabolome in both normal and pathological conditions are still unclear. In this study, we seek to provide a description of the knowledge to date of the IM and its metabolome and the factors that influence it. Furthermore, we analyze the interactions between the functions of the IM and the pathophysiology of major metabolic diseases via local and systemic metabolome's relate endotoxemia.

Research development on gut microbiota and vulnerable atherosclerotic plaque

The relationship between gut microbiota and its metabolites with cardiovascular disease (CVD) has been proven. In this review, we aim to conclude the potential mechanism of gut microbiota and its metabolites on inducing the formation of vulnerable atherosclerotic plaque, and to discuss the effect of intestinal metabolites, including trimethylamine-N-oxide (TMAO), lipopolysaccharide (LPS), phenylacetylglutamine (PAG), short-chain fatty acids (SCFAs) on plaque stability. Finally, we include the impact of gut microbiota and its metabolites on plaque stability, to propose a new therapeutic direction for coronary heart disease. Gut microbiota regulation intervenes the progress of arteriosclerosis, especially on coronary atherosclerosis, by avoiding or reducing the formation of vulnerable plaque, to lower the morbidity rate of myocardial infarction.

Intestinal microbiota regulates the gut-thyroid axis: the new dawn of improving Hashimoto thyroiditis

Intestinal microbiota plays an indispensable role in the host's innate immune system, which may be related to the occurrence of many autoimmune diseases. Hashimoto thyroiditis (HT) is one of the most common autoimmune diseases, and there is plenty of evidence indicating that HT may be related to genetics and environmental triggers, but the specific mechanism has not been proven clearly. Significantly, the composition and abundance of intestinal microbiota in patients with HT have an obvious difference. This phenomenon led us to think about whether intestinal microbiota can affect the progress of HT through some mechanisms. By summarizing the potential mechanism of intestinal microflora in regulating Hashimoto thyroiditis, this article explores the possibility of improving HT by regulating intestinal microbiota and summarizes relevant biomarkers as therapeutic targets, which provide new ideas for the clinical diagnosis and treatment of Hashimoto thyroiditis.

Interorgan communication in neurogenic heterotopic ossification: the role of brain-derived extracellular vesicles

Brain-derived extracellular vesicles participate in interorgan communication after traumatic brain injury by transporting pathogens to initiate secondary injury. Inflammasome-related proteins encapsulated in brain-derived extracellular vesicles can cross the blood‒brain barrier to reach distal tissues. These proteins initiate inflammatory dysfunction, such as neurogenic heterotopic ossification. This recurrent condition is highly debilitating to patients because of its relatively unknown pathogenesis and the lack of effective prophylactic intervention strategies. Accordingly, a rat model of neurogenic heterotopic ossification induced by combined traumatic brain injury and achillotenotomy was developed to address these two issues. Histological examination of the injured tendon revealed the coexistence of ectopic calcification and fibroblast pyroptosis. The relationships among brain-derived extracellular vesicles, fibroblast pyroptosis and ectopic calcification were further investigated in vitro and in vivo. Intravenous injection of the pyroptosis inhibitor Ac-YVAD-cmk reversed the development of neurogenic heterotopic ossification in vivo. The present work highlights the role of brain-derived extracellular vesicles in the pathogenesis of neurogenic heterotopic ossification and offers a potential strategy for preventing neurogenic heterotopic ossification after traumatic brain injury. Brain-derived extracellular vesicles (BEVs) are released after traumatic brain injury. These BEVs contain pathogens and participate in interorgan communication to initiate secondary injury in distal tissues. After achillotenotomy, the phagocytosis of BEVs by fibroblasts induces pyroptosis, which is a highly inflammatory form of lytic programmed cell death, in the injured tendon. Fibroblast pyroptosis leads to an increase in calcium and phosphorus concentrations and creates a microenvironment that promotes osteogenesis. Intravenous injection of the pyroptosis inhibitor Ac-YVAD-cmk suppressed fibroblast pyroptosis and effectively prevented the onset of heterotopic ossification after neuronal injury. The use of a pyroptosis inhibitor represents a potential strategy for the treatment of neurogenic heterotopic ossification.

Trimethylamine N-oxide promotes abdominal aortic aneurysm by inducing vascular inflammation and vascular smooth muscle cell phenotypic switching

OBJECTIVE

Inflammation and vascular smooth muscle cell (VSMC) phenotypic switching are implicated in the pathogenesis of abdominal aortic aneurysm (AAA). Trimethylamine N-oxide (TMAO) has emerged as a crucial risk factor in cardiovascular diseases, inducing vascular inflammation and calcification. We aimed to evaluate the effect of TMAO on the formation of AAA.

APPROACH AND RESULTS

Here, we showed that TMAO was elevated in plasma from AAA patients compared with nonaneurysmal subjects by liquid chromatography‒mass spectrometry (LC‒MS) detection. Functional studies revealed that increased TMAO induced by feeding a choline-supplemented diet promoted Ang II-induced AAA formation. Immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), and Western blot analyses revealed that TMAO induced macrophage infiltration and inflammatory factor release. Conversely, inhibition of TMAO by supplementation with DMB suppressed AAA formation and the inflammatory response. Molecular studies revealed that TMAO regulated VSMC phenotypic switching. Flow cytometry analyses showed that TMAO induces macrophage M1-type polarization. Furthermore, pharmacological intervention experiments suggested that the nuclear factor-κB (NF-κB) signaling pathway was critical for TMAO to trigger AAA formation.

CONCLUSIONS

TMAO promotes AAA formation by inducing vascular inflammation and VSMC phenotypic switching through activation of the NF-κB signaling pathway. Thus, TMAO is a prospective therapeutic AAA target.

Isoflavones Effects on Vascular and Endothelial Outcomes: How Is the Gut Microbiota Involved?

Isoflavones are a group of (poly)phenols, also defined as phytoestrogens, with chemical structures comparable with estrogen, that exert weak estrogenic effects. These phytochemical compounds have been targeted for their proven antioxidant and protective effects. Recognizing the increasing prevalence of cardiovascular diseases (CVD), there is a growing interest in understanding the potential cardiovascular benefits associated with these phytochemical compounds. Gut microbiota may play a key role in mediating the effects of isoflavones on vascular and endothelial functions, as it is directly implicated in isoflavones metabolism. The findings from randomized clinical trials indicate that isoflavone supplementation may exert putative effects on vascular biomarkers among healthy individuals, but not among patients affected by cardiometabolic disorders. These results might be explained by the enzymatic transformation to which isoflavones are subjected by the gut microbiota, suggesting that a diverse composition of the microbiota may determine the diverse bioavailability of these compounds. Specifically, the conversion of isoflavones in equol-a microbiota-derived metabolite-seems to differ between individuals. Further studies are needed to clarify the intricate molecular mechanisms behind these contrasting results.

Gut microbiota-dependent phenylacetylglutamine in cardiovascular disease: current knowledge and new insights

Phenylacetylglutamine (PAGln) is an amino acid derivate that comes from the amino acid phenylalanine. There are increasing studies showing that the level of PAGln is associated with the risk of different cardiovascular diseases. In this review, we discussed the metabolic pathway of PAGln production and the quantitative measurement methods of PAGln. We summarized the epidemiological evidence to show the role of PAGln in diagnostic and prognostic value in several cardiovascular diseases, such as heart failure, coronary heart disease/atherosclerosis, and cardiac arrhythmia. The underlying mechanism of PAGln is now considered to be related to the thrombotic potential of platelets via adrenergic receptors. Besides, other possible mechanisms such as inflammatory response and oxidative stress could also be induced by PAGln. Moreover, since PAGln is produced across different organs including the intestine, liver, and kidney, the cross-talk among multiple organs focused on the function of this uremic toxic metabolite. Finally, the prognostic value of PAGln compared to the classical biomarker was discussed and we also highlighted important gaps in knowledge and areas requiring future investigation of PAGln in cardiovascular diseases.

Mice, rats, and guinea pigs differ in FMOs expression and tissue concentration of TMAO, a gut bacteria-derived biomarker of cardiovascular and metabolic diseases

INTRODUCTION

Increased plasma trimethylamine oxide (TMAO) is observed in cardiovascular and metabolic diseases, originating from the gut microbiota product, trimethylamine (TMA), via flavin-containing monooxygenases (FMOs)-dependent oxidation. Numerous studies have investigated the association between plasma TMAO and various pathologies, yet limited knowledge exists regarding tissue concentrations of TMAO, TMAO precursors, and interspecies variability.

METHODS

Chromatography coupled with mass spectrometry was employed to evaluate tissue concentrations of TMAO and its precursors in adult male mice, rats, and guinea pigs. FMO mRNA and protein levels were assessed through PCR and Western blot, respectively.

RESULTS

Plasma TMAO levels were similar among the studied species. However, significant differences in tissue concentrations of TMAO were observed between mice, rats, and guinea pigs. The rat renal medulla exhibited the highest TMAO concentration, while the lowest was found in the mouse liver. Mice demonstrated significantly higher plasma TMA concentrations compared to rats and guinea pigs, with the highest TMA concentration found in the mouse renal medulla and the lowest in the rat lungs. FMO5 exhibited the highest expression in mouse liver, while FMO3 was highly expressed in rats. Guinea pigs displayed low expression of FMOs in this tissue.

CONCLUSION

Despite similar plasma TMAO levels, mice, rats, and guinea pigs exhibited significant differences in tissue concentrations of TMA, TMAO, and FMO expression. These interspecies variations should be considered in the design and interpretation of experimental studies. Furthermore, these findings may suggest a diverse importance of the TMAO pathway in the physiology of the evaluated species.

Prevotella copri promotes vascular calcification via lipopolysaccharide through activation of NF-κB signaling pathway

Emerging evidence indicates that alteration of gut microbiota plays an important role in chronic kidney disease (CKD)-related vascular calcification (VC). We aimed to investigate the specific gut microbiota and the underlying mechanism involved in CKD-VC. We identified an increased abundance of Prevotella copri (P. copri) in the feces of CKD rats (induced by using 5/6 nephrectomy followed by a high calcium and phosphate diet) with aortic calcification via amplicon sequencing of 16S rRNA genes. In patients with CKD, we further confirmed a positive correlation between abundance of P. copri and aortic calcification scores. Moreover, oral administration of live P. copri aggravated CKD-related VC and osteogenic differentiation of vascular smooth muscle cells in vivo, accompanied by intestinal destruction, enhanced expression of Toll-like receptor-4 (TLR4), and elevated lipopolysaccharide (LPS) levels. In vitro and ex vivo experiments consistently demonstrated that P. copri-derived LPS (Pc-LPS) accelerated high phosphate-induced VC and VSMC osteogenic differentiation. Mechanistically, Pc-LPS bound to TLR4, then activated the nuclear factor κB (NF-κB) and nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome signals during VC. Inhibition of NF-κB reduced NLRP3 inflammasome and attenuated Pc-LPS-induced VSMC calcification. Our study clarifies a novel role of P. copri in CKD-related VC, by the mechanisms involving increased inflammation-regulating metabolites including Pc-LPS, and activation of the NF-κB/NLRP3 signaling pathway. These findings highlight P. copri and its-derived LPS as potential therapeutic targets for VC in CKD.

Biomimetic Grapefruit-Derived Extracellular Vesicles for Safe and Targeted Delivery of Sodium Thiosulfate against Vascular Calcification

As the prevalence of vascular calcification (VC), a strong contributor to cardiovascular morbidity and mortality, continues to increase, the need for pharmacologic therapies becomes urgent. Sodium thiosulfate (STS) is a clinically approved drug for therapy against VC; however, its efficacy is hampered by poor bioavailability and severe adverse effects. Plant-derived extracellular vesicles have provided options for VC treatment since they can be used as biomimetic drug carriers with higher biosafety and targeting abilities than artificial carriers. Inspired by natural grapefruit-derived extracellular vesicles (EVs), we fabricated a biomimetic nanocarrier comprising EVs loaded with STS and further modified with hydroxyapatite crystal binding peptide (ESTP) for VC-targeted delivery of STS. In vitro, the ESTP nanodrug exhibited excellent cellular uptake capacity by calcified vascular smooth muscle cells (VSMCs) and subsequently inhibited VSMCs calcification. In the VC mice model, the ESTP nanodrug showed preferentially the highest accumulation in the calcified arteries compared to other treatment groups. Mechanistically, the ESTP nanodrug significantly prevented VC via driving M2 macrophage polarization, reducing inflammation, and suppressing bone-vascular axis as demonstrated by inhibiting osteogenic phenotype trans-differentiation of VSMCs while enhancing bone quality. In addition, the ESTP nanodrug did not induce hemolysis or cause any damage to other organs. These results suggest that the ESTP nanodrug can prove to be a promising agent against VC without the concern of systemic toxicity.

Trimethylamine N-Oxide as a Mediator Linking Peripheral to Central Inflammation: An In Vitro Study

In this study, the plausible role of trimethylamine N-oxide (TMAO), a microbiota metabolite, was investigated as a link between peripheral inflammation and the inflammation of the central nervous system using different cell lines. TMAO treatment favored the differentiation of adipocytes from preadipocytes (3T3-L1 cell line). In macrophages (RAW 264.7 cell line), which infiltrate adipose tissue in obesity, TMAO increased the expression of pro-inflammatory cytokines. The treatment with 200 μM of TMAO seemed to disrupt the blood-brain barrier as it induced a significant decrease in the expression of occludin in hCMECs. TMAO also increased the expression of pro-inflammatory cytokines in primary neuronal cultures, induced a pro-inflammatory state in primary microglial cultures, and promoted phagocytosis. Data obtained from this project suggest that microbial dysbiosis and increased TMAO secretion could be a key link between peripheral and central inflammation. Thus, TMAO-decreasing compounds may be a promising therapeutic strategy for neurodegenerative diseases.

Beyond the Basics: Unraveling the Complexity of Coronary Artery Calcification

Coronary artery calcification (CAC) is mainly associated with coronary atherosclerosis, which is an indicator of coronary artery disease (CAD). CAC refers to the accumulation of calcium phosphate deposits, classified as micro- or macrocalcifications, that lead to the hardening and narrowing of the coronary arteries. CAC is a strong predictor of future cardiovascular events, such as myocardial infarction and sudden death. Our narrative review focuses on the pathophysiology of CAC, exploring its link to plaque vulnerability, genetic factors, and how race and sex can affect the condition. We also examined the connection between the gut microbiome and CAC, and the impact of genetic variants on the cellular processes involved in vascular calcification and atherogenesis. We aimed to thoroughly analyze the existing literature to improve our understanding of CAC and its potential clinical and therapeutic implications.

Dietary antioxidants and vascular calcification: From pharmacological mechanisms to challenges

Vascular calcification (VC), an actively regulated process, has been recognized as an independent and strong predictor of cardiovascular disease (CVD) and mortality worldwide. Diet has been shown to have a major role in the progression of VC. Oxidative stress (OS), a common pro-calcification factor, is closely related to VC, and evidence strongly suggests that dietary antioxidants directly prevent VC. Herein, we provided an overview of OS and its key role in VC and underlined the mechanisms of harmful effects of OS on VC. Furthermore, we introduced dietary antioxidants, and discussed about surrounding the challenges of dietary antioxidants in VC management. This review will benefit future research about the effects of dietary antioxidants on cardiovascular health.

Phenylacetylglutamine and trimethylamine N-oxide: Two uremic players, different actions

BACKGROUND

Chronic kidney disease (CKD) patients exhibit a heightened cardiovascular (CV) risk which may be partially explained by increased medial vascular calcification. Although gut-derived uremic toxin trimethylamine N-oxide (TMAO) is associated with calcium-phosphate deposition, studies investigating phenylacetylglutamine's (PAG) pro-calcifying potential are missing.

METHODS

The effect of TMAO and PAG in vascular calcification was investigated using 120 kidney failure patients undergoing living-donor kidney transplantation (LD-KTx), in an observational, cross-sectional manner. Uremic toxin concentrations were related to coronary artery calcification (CAC) score, epigastric artery calcification score, and markers of established non-traditional risk factors that constitute to the 'perfect storm' that drives early vascular aging in this patient population. Vascular smooth muscle cells were incubated with TMAO or PAG to determine their calcifying effects in vitro and analyse associated pathways by which these toxins may promote vascular calcification.

RESULTS

TMAO, but not PAG, was independently associated with CAC score after adjustment for CKD-related risk factors in kidney failure patients. Neither toxin was associated with epigastric artery calcification score; however, PAG was independently, positively associated with 8-hydroxydeoxyguanosine. Similarly, TMAO, but not PAG, promoted calcium-phosphate deposition in vitro, while both uremic solutes induced oxidative stress.

CONCLUSIONS

In conclusion, our translational data confirm TMAO's pro-calcifying effects, but both toxins induced free radical production detrimental to vascular maintenance. Our findings suggest these gut-derived uremic toxins have different actions on the vessel wall and therapeutically targeting TMAO may help reduce CV-related mortality in CKD.

Phosphate burden induces vascular calcification through a NLRP3-caspase-1-mediated pyroptotic pathway

AIMS

The aim of this study is to clarify the role of NLRP3 inflammasome in phosphate burden-induced vascular smooth muscle cell (VSMC) calcification.

MAIN METHODS

VSMC calcification was induced using a high concentration of inorganic phosphate. After pharmacological inhibition or genetic silencing of the NLRP3 inflammasome, pyroptosis, or potassium efflux, the cells were examined by RT-qPCR, immunofluorescence, and western blotting to identify the NLRP3-mediated pathway for VSMC calcification.

KEY FINDINGS

Calcified VSMCs with α-smooth muscle actin (α-SMA) disarray presented features of pyroptosis, including caspase-1 maturation, cleaved gasdermin D (GSDMD), and a high supernatant level of lactate dehydrogenase A. Pharmacological inhibitions of caspase-1 and pyroptosis attenuated VSMC calcification, whereas interleukin-1β receptor antagonism did not. Unlike canonical NLRP3 activation, osteogenic VSMCs did not upregulate NLRP3 expression. However, NLRP3 genetic silencing or inhibitions, which targets different domains of the NLRP3 protein, could ameliorate VSMC calcification by aborting caspase-1 and GSDMD activation. Furthermore, potassium efflux through the inward-rectifier potassium channel, and not through the P2X7 receptor, triggered NLRP3 inflammasome activation and VSMC calcification.

SIGNIFICANCE

In the present study, we identified a potassium efflux-triggered NLRP3-caspase-1-mediated pyroptotic pathway for VSMC calcification that is unique and different from the canonical NLRP3 inflammasome activation. Therefore, targeting this pathway may serve as a novel therapeutic strategy for vascular calcification.

Insights into the intestinal toxicity of foodborne mycotoxins through gut microbiota: A comprehensive review

Mycotoxins, which are fungal metabolites, pose a significant global food safety concern by extensively contaminating food and feed, thereby seriously threatening public health and economic development. Many foodborne mycotoxins exhibit potent intestinal toxicity. However, the mechanisms underlying mycotoxin-induced intestinal toxicity are diverse and complex, and effective prevention or treatment methods for this condition have not yet been established in clinical and animal husbandry practices. In recent years, there has been increasing attention to the role of gut microbiota in the occurrence and development of intestinal diseases. Hence, this review aims to provide a comprehensive summary of the intestinal toxicity mechanisms of six common foodborne mycotoxins. It also explores novel toxicity mechanisms through the "key gut microbiota-key metabolites-key targets" axis, utilizing multiomics and precision toxicology studies with a specific focus on gut microbiota. Additionally, we examine the potential beneficial effects of probiotic supplementation on mycotoxin-induced toxicity based on initial gut microbiota-mediated mycotoxicity. This review offers a systematic description of how mycotoxins impact gut microbiota, metabolites, and genes or proteins, providing valuable insights for subsequent toxicity studies of mycotoxins. Furthermore, it lays a theoretical foundation for preventing and treating intestinal toxicity caused by mycotoxins and advancing food safety practices.

Emerging Evidence Linking the Liver to the Cardiovascular System: Liver-derived Secretory Factors

Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality worldwide. Recently, accumulating evidence has revealed hepatic mediators, termed as liver-derived secretory factors (LDSFs), play an important role in regulating CVDs such as atherosclerosis, coronary artery disease, thrombosis, myocardial infarction, heart failure, metabolic cardiomyopathy, arterial hypertension, and pulmonary hypertension. LDSFs presented here consisted of microbial metabolite, extracellular vesicles, proteins, and microRNA, they are primarily or exclusively synthesized and released by the liver, and have been shown to exert pleiotropic actions on cardiovascular system. LDSFs mainly target vascular endothelial cell, vascular smooth muscle cells, cardiomyocytes, fibroblasts, macrophages and platelets, and further modulate endothelial nitric oxide synthase/nitric oxide, endothelial function, energy metabolism, inflammation, oxidative stress, and dystrophic calcification. Although some LDSFs are known to be detrimental/beneficial, controversial findings were also reported for many. Therefore, more studies are required to further explore the causal relationships between LDSFs and CVDs and uncover the exact mechanisms, which is expected to extend our understanding of the crosstalk between the liver and cardiovascular system and identify potential therapeutic targets. Furthermore, in the case of patients with liver disease, awareness should be given to the implications of these abnormalities in the cardiovascular system. These studies also underline the importance of early recognition and intervention of liver abnormalities in the practice of cardiovascular care, and a multidisciplinary approach combining hepatologists and cardiologists would be more preferable for such patients.

Vascular calcification: from the perspective of crosstalk

Vascular calcification (VC) is highly correlated with cardiovascular disease morbidity and mortality, but anti-VC treatment remains an area to be tackled due to the ill-defined molecular mechanisms. Regardless of the type of VC, it does not depend on a single cell but involves multi-cells/organs to form a complex cellular communication network through the vascular microenvironment to participate in the occurrence and development of VC. Therefore, focusing only on the direct effect of pathological factors on vascular smooth muscle cells (VSMCs) tends to overlook the combined effect of other cells and VSMCs, including VSMCs-VSMCs, ECs-VMSCs, Macrophages-VSMCs, etc. Extracellular vesicles (EVs) are a collective term for tiny vesicles with a membrane structure that are actively secreted by cells, and almost all cells secrete EVs. EVs docked on the surface of receptor cells can directly mediate signal transduction or transfer their contents into the cell to elicit a functional response from the receptor cells. They have been proven to participate in the VC process and have also shown attractive therapeutic prospects. Based on the advantages of EVs and the ability to be detected in body fluids, they may become a novel therapeutic agent, drug delivery vehicle, diagnostic and prognostic biomarker, and potential therapeutic target in the future. This review focuses on the new insight into VC molecular mechanisms from the perspective of crosstalk, summarizes how multi-cells/organs interactions communicate via EVs to regulate VC and the emerging potential of EVs as therapeutic methods in VC. We also summarize preclinical experiments on crosstalk-based and the current state of clinical studies on VC-related measures.

Lactobacillus rhamnosus GG aggravates vascular calcification in chronic kidney disease: A potential role for extracellular vesicles

AIMS

Lactobacillus rhamnosus GG (LGG) is a probiotic with great promise in future clinical application, which can significantly promote bone formation. However, the effect of LGG on CKD-related vascular calcification is unclear. In this study, we aimed to investigate the effect of LGG on CKD-related vascular calcification.

MATERIALS AND METHODS

After 2 weeks of 5/6 nephrectomy, CKD rats received a special diet (4 % calcium and 1.8 % phosphate) combined with 1,25-dihydroxyvitamin D3 to induce vascular calcification. Meanwhile, CKD rats in the LGG group were gavaged orally with LGG (1 × 109 CFU bacteria/day). 16S RNA amplicon sequencing was performed to analyze the effect of LGG treatment on gut microbiota composition. Furthermore, differential ultracentrifugation was utilized to extract EVs. The effects of EVs on vascular calcification were evaluated in rat VSMCs, rat aortic rings, and CKD rat calcification models. In this study, vascular calcification was assessed by microcomputed tomography analysis, alizarin red staining, calcium content determination, and the expression of osteogenic transcription factors RUNX2 and BMP2.

KEY FINDINGS

LGG remarkably aggravated vascular calcification. LGG supplementation significantly altered gut microbiota composition in CKD rats, particularly increasing Lactobacillus. Interestingly, EVs presented a significant promoting effect on the development of calcification. Finally, mechanistic analysis proved that EVs aggravated vascular calcification through PI3K/AKT signaling.

SIGNIFICANCE

These results do not support the supplementation of LGG in CKD-associated vascular calcification patients. Our study presented a fresh perspective on LGG with potential risks and adverse effects. CKD patients should use specific probiotic strains cautiously.

Increased circulating phenylacetylglutamine concentration elevates the predictive value of cardiovascular event risk in heart failure patients

BACKGROUND

Phenylacetylglutamine (PAGln)-a newly discovered microbial metabolite produced by phenylalanine metabolism-is reportedly associated with cardiovascular events via adrenergic receptors. Nonetheless, its association with cardiovascular outcomes in heart failure (HF) patients remains unknown.

OBJECTIVES

This study aimed to prospectively investigate the prognostic value of PAGln for HF.

METHODS

Plasma PAGln levels were quantified by liquid chromatography-tandem mass spectrometry. We first assessed the association between plasma PAGln levels and the incidence of adverse cardiovascular events in 3152 HF patients (including HF with preserved and reduced ejection fraction) over a median follow-up period of 2 years. The primary endpoint was the composite of cardiovascular death or heart transplantation. We then assessed the prognostic role of PAGln in addition to the classic biomarker N-terminal pro-B-type natriuretic peptide (NT-proBNP). The correlation between PAGln levels and β-blocker use was also investigated.

RESULTS

In total, 520 cardiovascular deaths or heart transplantations occurred in the HF cohort. Elevated PAGln levels were independently associated with a higher risk of the primary endpoint in a dose-response manner, regardless of HF subtype. Concurrent assessment of PAGln and NT-proBNP levels enhanced risk stratification among HF patients. PAGln further showed prognostic value at low NT-proBNP levels. Additionally, the interaction effects between PAGln and β-blocker use were not significant.

CONCLUSIONS

Plasma PAGln levels are an independent predictor of an increased risk of adverse cardiovascular events in HF. Our work could provide joint and complementary prognostic value to NT-proBNP levels in HF patients.

Inflammation and gut dysbiosis as drivers of CKD-MBD

Two decades ago, Kidney Disease: Improving Global Outcomes coined the term chronic kidney disease-mineral and bone disorder (CKD-MBD) to describe the syndrome of biochemical, bone and extra-skeletal calcification abnormalities that occur in patients with CKD. CKD-MBD is a prevalent complication and contributes to the excessively high burden of fractures and cardiovascular disease, loss of quality of life and premature mortality in patients with CKD. Thus far, therapy has focused primarily on phosphate retention, abnormal vitamin D metabolism and parathyroid hormone disturbances, but these strategies have largely proved unsuccessful, thus calling for paradigm-shifting concepts and innovative therapeutic approaches. Interorgan crosstalk is increasingly acknowledged to have an important role in health and disease. Accordingly, mounting evidence suggests a role for both the immune system and the gut microbiome in bone and vascular biology. Gut dysbiosis, compromised gut epithelial barrier and immune cell dysfunction are prominent features of the uraemic milieu. These alterations might contribute to the inflammatory state observed in CKD and could have a central role in the pathogenesis of CKD-MBD. The emerging fields of osteoimmunology and osteomicrobiology add another level of complexity to the pathogenesis of CKD-MBD, but also create novel therapeutic opportunities.

Research progress of diabetic retinopathy and gut microecology

According to the prediction of the International Diabetes Federation, global diabetes mellitus (DM) patients will reach 783.2 million in 2045. The increasing incidence of DM has led to a global epidemic of diabetic retinopathy (DR). DR is a common microvascular complication of DM, which has a significant impact on the vision of working-age people and is one of the main causes of blindness worldwide. Substantial research has highlighted that microangiopathy and chronic low-grade inflammation are widespread in the retina of DR. Meanwhile, with the introduction of the gut-retina axis, it has also been found that DR is associated with gut microecological disorders. The disordered structure of the GM and the destruction of the gut barrier result in the release of abnormal GM flora metabolites into the blood circulation. In addition, this process induced alterations in the expression of various cytokines and proteins, which further modulate the inflammatory microenvironment, vascular damage, oxidative stress, and immune levels within the retina. Such alterations led to the development of DR. In this review, we discuss the corresponding alterations in the structure of the GM flora and its metabolites in DR, with a more detailed focus on the mechanism of gut microecology in DR. Finally, we summarize the potential therapeutic approaches of DM/DR, mainly regulating the disturbed gut microecology to restore the homeostatic level, to provide a new perspective on the prevention, monitoring, and treatment of DR.

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

Objective

Stroke is a kind of cerebrovascular disease with high mortality. TMAO has been shown to aggravate stroke outcomes, but its mechanism remains unclear.

Materials and Methods

Mice were fed with 0.12% TMAO for 16 weeks. Then, mice were made into MCAO/R models. Neurological score, infarct volume, neuronal damage and markers associated with inflammation were assessed. Since microglia played a crucial role in ischemic stroke, microglia of MCAO/R mice were isolated for high-throughput sequencing to identify the most differentially expressed gene following TMAO treatment. Afterward, the downstream pathways of TMAO were investigated using primary microglia.

Results

TMAO promoted the release of inflammatory cytokines in the brain of MCAO/R mice and promoted the activation of OGD/R microglial inflammasome, thereby exacerbating ischemic stroke outcomes. FTO/IGF2BP2 inhibited NLRP3 inflammasome activation in OGD/R microglia by downregulating the m6A level of NLRP3. TMAO can inhibit the expression of FTO and IGF2BP2, thus promoting the activation of NLRP3 inflammasome in OGD/R microglia. In conclusion, these results demonstrated that TMAO promotes NLRP3 inflammasome activation of microglia aggravating neurological injury in ischemic stroke through FTO/IGF2BP2.

Conclusion

Our results demonstrated that TMAO promotes NLRP3 inflammasome activation of microglia aggravating neurological injury in ischemic stroke through FTO/IGF2BP2. These findings explained the molecular mechanism of TMAO aggravating ischemic stroke in detail and provided molecular mechanism for clinical treatment.

Targeted inhibition of PTPN22 is a novel approach to alleviate osteogenic responses in aortic valve interstitial cells and aortic valve lesions in mice

BACKGROUND

Calcific aortic valve disease (CAVD) is the most prevalent valvular disease and has high morbidity and mortality. CAVD is characterized by complex pathophysiological processes, including inflammation-induced osteoblastic differentiation in aortic valve interstitial cells (AVICs). Novel anti-CAVD agents are urgently needed. Protein tyrosine phosphatase nonreceptor type 22 (PTPN22), an intracellular nonreceptor-like protein tyrosine phosphatase, is involved in several chronic inflammatory diseases, including rheumatoid arthritis and diabetes. However, it is unclear whether PTPN22 is involved in the pathogenesis of CAVD.

METHODS

We obtained the aortic valve tissue from human and cultured AVICs from aortic valve. We established CAVD mice model by wire injury. Transcriptome sequencing, western bolt, qPCR, and immunofluorescence were performed to elucidate the molecular mechanisms.

RESULTS

Here, we determined that PTPN22 expression was upregulated in calcific aortic valve tissue, AVICs treated with osteogenic medium, and a mouse model of CAVD. In vitro, overexpression of PTPN22 induced osteogenic responses, whereas siRNA-mediated PTPN22 knockdown abolished osteogenic responses and mitochondrial stress in the presence of osteogenic medium. In vivo, PTPN22 ablation ameliorated aortic valve lesions in a wire injury-induced CAVD mouse model, validating the pathogenic role of PTPN22 in CAVD. Additionally, we discovered a novel compound, 13-hydroxypiericidin A 10-O-α-D-glucose (1 → 6)-β-D-glucoside (S18), in a marine-derived Streptomyces strain that bound to PTPN22 with high affinity and acted as a novel inhibitor. Incubation with S18 suppressed osteogenic responses and mitochondrial stress in human AVICs induced by osteogenic medium. In mice with aortic valve injury, S18 administration markedly alleviated aortic valve lesions.

CONCLUSION

PTPN22 plays an essential role in the progression of CAVD, and inhibition of PTPN22 with S18 is a novel option for the further development of potent anti-CAVD drugs. Therapeutic inhibition of PTPN22 retards aortic valve calcification through modulating mitochondrial dysfunction in AVICs.

The role of microbial metabolites in diabetic kidney disease

Background

Growing evidence suggests a complex bidirectional interaction between gut microbes, gut-derived microbial metabolites, and diabetic kidney disease (DKD), known as the "gut-kidney axis" theory. The present study aimed to characterize the role of microbial metabolites in DKD.

Methods

Six-week-old db/db and littermate db/m mice were raised to 20 weeks old. The serum, urine, feces, liver, perinephric fat, and kidney were analyzed using liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based metabolomic analyses.

Results

The db/db mice showed obvious pathological changes and worse renal functions than db/m mice. Indoleacetaldehyde (IAld) and 5-hydroxy-l-tryptophan (5-HTP) in kidney samples, and serotonin (5-HT) in fecal samples were increased in the db/db group. Phosphatidylcholine (PC), phosphatidate (PA), and 1-acylglycerophosphocholine (lysoPC) were decreased in liver and serum samples of the db/db group, while PC and lysoPC were decreased in kidney and perinephric fat samples. Suggested metabolomic homeostasis was disrupted in DKD mice, especially glycerophospholipid and tryptophan metabolism, which are closely related to the gut microbiome.

Conclusions

Our findings reveal the perturbation of gut microbial metabolism in db/db mice with DKD, which may be useful for building a bridge between the gut microbiota and the progression of DKD and provide a theoretical basis for the intestinal treatment of DKD.

The Impacts of Animal-Based Diets in Cardiovascular Disease Development: A Cellular and Physiological Overview

Cardiovascular disease (CVD) is the leading cause of death in the United States, and diet plays an instrumental role in CVD development. Plant-based diets have been strongly tied to a reduction in CVD incidence. In contrast, animal food consumption may increase CVD risk. While increased serum low-density lipoprotein (LDL) cholesterol concentrations are an established risk factor which may partially explain the positive association with animal foods and CVD, numerous other biochemical factors are also at play. Thus, the aim of this review is to summarize the major cellular and molecular effects of animal food consumption in relation to CVD development. Animal-food-centered diets may (1) increase cardiovascular toll-like receptor (TLR) signaling, due to increased serum endotoxins and oxidized LDL cholesterol, (2) increase cardiovascular lipotoxicity, (3) increase renin-angiotensin system components and subsequent angiotensin II type-1 receptor (AT1R) signaling and (4) increase serum trimethylamine-N-oxide concentrations. These nutritionally mediated factors independently increase cardiovascular oxidative stress and inflammation and are all independently tied to CVD development. Public policy efforts should continue to advocate for the consumption of a mostly plant-based diet, with the minimization of animal-based foods.

Dietary Patterns, Gut Microbiota Remodeling, and Cardiometabolic Disease

The cardiovascular and metabolic disorders, collectively known as cardiometabolic disease (CMD), are high morbidity and mortality pathologies associated with lower quality of life and increasing health-care costs. The influence of the gut microbiota (GM) in dictating the interpersonal variability in CMD susceptibility, progression and treatment response is beginning to be deciphered, as is the mutualistic relation established between the GM and diet. In particular, dietary factors emerge as pivotal determinants shaping the architecture and function of resident microorganisms in the human gut. In turn, intestinal microbes influence the absorption, metabolism, and storage of ingested nutrients, with potentially profound effects on host physiology. Herein, we present an updated overview on major effects of dietary components on the GM, highlighting the beneficial and detrimental consequences of diet-microbiota crosstalk in the setting of CMD. We also discuss the promises and challenges of integrating microbiome data in dietary planning aimed at restraining CMD onset and progression with a more personalized nutritional approach.

Trimethylamine N-oxide is associated with long-term mortality risk: the multi-ethnic study of atherosclerosis

AIMS

Little is known about associations of trimethylamine N-oxide (TMAO), a novel gut microbiota-generated metabolite of dietary phosphatidylcholine and carnitine, and its changes over time with all-cause and cause-specific mortality in the general population or in different race/ethnicity groups. The study aimed to investigate associations of serially measured plasma TMAO levels and changes in TMAO over time with all-cause and cause-specific mortality in a multi-ethnic community-based cohort.

METHODS AND RESULTS

The study included 6,785 adults from the Multi-Ethnic Study of Atherosclerosis. TMAO was measured at baseline and year 5 using mass spectrometry. Primary outcomes were adjudicated all-cause mortality and cardiovascular disease (CVD) mortality. Secondary outcomes were deaths due to kidney failure, cancer, or dementia obtained from death certificates. Cox proportional hazards models with time-varying TMAO and covariates assessed the associations with adjustment for sociodemographics, lifestyles, diet, metabolic factors, and comorbidities. During a median follow-up of 16.9 years, 1704 participants died and 411 from CVD. Higher TMAO levels associated with higher risk of all-cause mortality [hazard ratio (HR): 1.12, 95% confidence interval (CI): 1.08-1.17], CVD mortality (HR: 1.09, 95% CI: 1.00-1.09), and death due to kidney failure (HR: 1.44, 95% CI: 1.25-1.66) per inter-quintile range, but not deaths due to cancer or dementia. Annualized changes in TMAO levels associated with higher risk of all-cause mortality (HR: 1.10, 95% CI: 1.05-1.14) and death due to kidney failure (HR: 1.54, 95% CI: 1.26-1.89) but not other deaths.

CONCLUSION

Plasma TMAO levels were positively associated with mortality, especially deaths due to cardiovascular and renal disease, in a multi-ethnic US cohort.

Extrahepatic Outcomes of Nonalcoholic Fatty Liver Disease: Cardiovascular Diseases

Patients with nonalcoholic fatty liver disease (NAFLD) are at high risk of cardiovascular disease, including carotid atherosclerosis, coronary artery disease, heart failure, and arrhythmias. The risk is partially due to shared risk factors, but it may vary according to liver injury. A fatty liver may induce an atherogenic profile, the local necro-inflammatory changes of nonalcoholic steatohepatitis may enhance systemic metabolic inflammation, and fibrogenesis can run parallel in the liver and in the myocardium and precedes heart failure. The detrimental impact of a Western diet combines with polymorphisms in genes associated with atherogenic dyslipidemia. Shared clinical/diagnostic algorithms are needed to manage the cardiovascular risk in NAFLD.

Trimethylamine N-Oxide (TMAO) Inducing Endothelial Injury: UPLC-MS/MS-Based Quantification and the Activation of Cathepsin B-Mediated NLRP3 Inflammasome

TMAO is a new risk biomarker for cardiovascular disease. With trimethylammonium as its main chemical skeleton, TMAO is structurally similar to many endogenous metabolites, such as acetylcholine, carnitine, phosphorylcholine, etc. The mechanism of TMAO on the pathological process of CVD is still unclear. In this study, the quantitative analysis of plasma TMAO is conducted, and the contribution of Cathepsin B and NLRP3 inflammasome during the process of TMAO-induced endothelial injury was proposed and investigated at animal and cellular levels. Immunofluorescence assay was applied to represent the protein expression of Cathepsin B and NLRP3 inflammasome located at endothelial cells. The results showed that TMAO could disrupt endothelial cells permeability to induce endothelial injury, meanwhile, TMAO could increase NLRP3 inflammasome activation and promote the activity and expression of Cathepsin B in vitro and in vivo, whereas inhibition of NLRP3 inflammasome activation by MCC950 could protect the endothelial cells from TMAO associated endothelial injury via Cathepsin B. The study reveals that TMAO can cause endothelial injury via Cathepsin B-dependent NLRP3 inflammasome, and inhibition of Cathepsin B and NLRP3 inflammasome can reduce the TMAO-induced damage. The results provide new insight into the role of TMAO in CVD, which can be a potential therapeutic target for disease treatment and drug design.

Role of the Microbiome in Gut-Heart-Kidney Cross Talk

Homeostasis is a prerequisite for health. When homeostasis becomes disrupted, dysfunction occurs. This is especially the case for the gut microbiota, which under normal conditions lives in symbiosis with the host. As there are as many microbial cells in and on our body as human cells, it is unlikely they would not contribute to health or disease. The gut bacterial metabolism generates numerous beneficial metabolites but also uremic toxins and their precursors, which are transported into the circulation. Barrier function in the intestine, the heart, and the kidneys regulates metabolite transport and concentration and plays a role in inter-organ and inter-organism communication via small molecules. This communication is analyzed from the perspective of the remote sensing and signaling theory, which emphasizes the role of a large network of multispecific, oligospecific, and monospecific transporters and enzymes in regulating small-molecule homeostasis. The theory provides a systems biology framework for understanding organ cross talk and microbe-host communication involving metabolites, signaling molecules, nutrients, antioxidants, and uremic toxins. This remote small-molecule communication is critical for maintenance of homeostasis along the gut-heart-kidney axis and for responding to homeostatic perturbations. Chronic kidney disease is characterized by gut dysbiosis and accumulation of toxic metabolites. This slowly impacts the body, affecting the cardiovascular system and contributing to the progression of kidney dysfunction, which in its turn influences the gut microbiota. Preserving gut homeostasis and barrier functions or restoring gut dysbiosis and dysfunction could be a minimally invasive way to improve patient outcomes and quality of life in many diseases, including cardiovascular and kidney disease.

Modulation of Endothelial Function by TMAO, a Gut Microbiota-Derived Metabolite

Endothelial function is essential in the maintenance of systemic homeostasis, whose modulation strictly depends on the proper activity of tissue-specific angiocrine factors on the physiopathological mechanisms acting at both single and multi-organ levels. Several angiocrine factors take part in the vascular function itself by modulating vascular tone, inflammatory response, and thrombotic state. Recent evidence has outlined a strong relationship between endothelial factors and gut microbiota-derived molecules. In particular, the direct involvement of trimethylamine N-oxide (TMAO) in the development of endothelial dysfunction and its derived pathological outcomes, such as atherosclerosis, has come to light. Indeed, the role of TMAO in the modulation of factors strictly related to the development of endothelial dysfunction, such as nitric oxide, adhesion molecules (ICAM-1, VCAM-1, and selectins), and IL-6, has been widely accepted. The aim of this review is to present the latest studies that describe a direct role of TMAO in the modulation of angiocrine factors primarily involved in the development of vascular pathologies.

Intestinal Flora Metabolite Trimethylamine Oxide Is Inextricably Linked to Coronary Heart Disease

ABSTRACT

Atherosclerotic coronary heart disease is a common cardiovascular disease with high morbidity and mortality. In recent years, the incidence of coronary heart disease has gradually become younger, and biomarkers for predicting coronary heart disease have demonstrated valuable clinical prospects. Several studies have established an association between coronary heart disease and intestinal flora metabolites, including trimethylamine oxide (TMAO), which has attracted widespread attention from researchers. Investigations have also shown that plasma levels of TMAO and its precursors can predict cardiovascular risk in humans; however, TMAO's mechanism of action in causing coronary heart disease is not fully understood. This review examines TMAO's generation, the mechanism through which it causes coronary heart disease, and the approaches used to treat TMAO-caused coronary heart disease to possible avenues for future research on coronary heart disease and find new concepts for the treatment of the condition.

The role of gut-dependent molecule trimethylamine N-oxide as a novel target for the treatment of chronic kidney disease

Trimethylamine N-oxide (TMAO) is an intestinal uremic toxin molecule mainly excreted by the kidney. Therefore, the plasma TMAO concentration is significantly increased in chronic kidney disease (CKD) patients, and plasma TMAO can be cleared by dialysis. Furthermore, TMAO damage the kidney mainly through three mechanisms: oxidative stress, inflammation and endoplasmic reticulum stress. Clinical experiments have indicated that higher TMAO levels are strongly related to the elevated incidence and mortality of cardiovascular (CV) events in CKD patients. Moreover, experimental data have shown that high levels of TMAO directly aggravate atherosclerosis, thrombosis and enhance myocardial contractility, resulting in myocardial ischemia and stroke. Specially, there are currently four potential ways to reduce blood TMAO concentration or block the effect of TMAO, including reducing the intake of trimethylamine (TMA) precursors in the diet, regulating the intestinal flora to reduce TMA production, interrupting the role of flavin-dependent monooxygenase isoforms (FMOs) to reduce the generation of TMAO, and blocking the TMAO receptor protein kinase R-like endoplasmic reticulum kinase (PERK). We hope that more clinical studies and clinicians will focus on clinical treatment to reduce the concentration of TMAO and alleviate renal damage.

Gut Molecules in Cardiometabolic Diseases: The Mechanisms behind the Story

Atherosclerotic cardiovascular disease is the most common cause of morbidity and mortality worldwide. Diabetes mellitus increases cardiovascular risk. Heart failure and atrial fibrillation are associated comorbidities that share the main cardiovascular risk factors. The use of incretin-based therapies promoted the idea that activation of alternative signaling pathways is effective in reducing the risk of atherosclerosis and heart failure. Gut-derived molecules, gut hormones, and gut microbiota metabolites showed both positive and detrimental effects in cardiometabolic disorders. Although inflammation plays a key role in cardiometabolic disorders, additional intracellular signaling pathways are involved and could explain the observed effects. Revealing the involved molecular mechanisms could provide novel therapeutic strategies and a better understanding of the relationship between the gut, metabolic syndrome, and cardiovascular diseases.