Trimethylamine-N-oxide promotes osteoclast differentiation and oxidative stress by activating NF-κB pathway.

BACKGROUND: Senile osteoporosis may be caused by an imbalance in intestinal flora and oxidative stress. Trimethylamine-N-oxide (TMAO), a metabolite of dietary choline dependent on gut microbes, has been found to be significantly increased in osteoporosis. However, the role of TMAO in bone loss during osteoporosis remains poorly understood. In this study, we examined the impact of TMAO on osteoclast differentiation and bone resorption in an in vitro setting. METHODS: Osteoclast differentiation was induced by incubating RAW 264.7 cells in the presence of Receptor Activator for Nuclear Factor-κB Ligand (RANKL) and macrophage-stimulating factor (M-CSF). Flow cytometry, TRAP staining assay, CCK-8, and ELISA were employed to investigate the impact of TMAO on osteoclast differentiation and bone resorption activity in vitro. For mechanistic exploration, RT-PCR and Western blotting were utilized to assess the activation of the NF-κB pathway. Additionally, protein levels of secreted cytokines and growth factors were determined using suspension array technology. RESULTS: Our findings demonstrate that TMAO enhances RANKL and M-CSF-induced osteoclast formation and bone resorption in a dose-dependent manner. Mechanistically, TMAO triggers the upregulation of the NF-κB pathway and osteoclast-related genes (NFATc1, c-Fos, NF-κB p65, Traf6, and Cathepsin K). Furthermore, TMAO markedly elevated the levels of oxidative stress and inflammatory factors. CONCLUSIONS: In conclusion, TMAO enhances RANKL and M-CSF-induced osteoclast differentiation and inflammation in RAW 264.7 cells by activating the NF-κB signaling pathway. These findings offer a new rationale for further academic and clinical research on osteoporosis treatment.

Network and Experimental Pharmacology on Mechanism of Yixintai Regulates the TMAO/PKC/NF-κB Signaling Pathway in Treating Heart Failure.

Objective: This study aims to explore the mechanism of action of Yixintai in treating chronic ischemic heart failure by combining bioinformatics and experimental validation. Materials and Methods: Five potential drugs for treating heart failure were obtained from Yixintai (YXT) through early mass spectrometry detection. The targets of YXT for treating heart failure were obtained by a search of online databases. Gene ontology (GO) functional enrichment analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analyses were conducted on the common targets using the DAVID database. A rat heart failure model was established by ligating the anterior descending branch of the left coronary artery. A small animal color Doppler ultrasound imaging system detected cardiac function indicators. Hematoxylin-eosin (HE), Masson's, and electron microscopy were used to observe the pathological morphology of the myocardium in rats with heart failure. The network pharmacology analysis results were validated by ELISA, qPCR, and Western blotting. Results: A total of 107 effective targets were obtained by combining compound targets and eliminating duplicate values. PPI analysis showed that inflammation-related proteins (TNF and IL1B) were key targets for treating heart failure, and KEGG enrichment suggested that NF-κB signaling pathway was a key pathway for YXT treatment of heart failure. Animal model validation results indicated the following: YXT can significantly reduce the content of intestinal microbiota metabolites such as trimethylamine oxide (TMAO) and improve heart failure by improving the EF and FS values of heart ultrasound in rats and reducing the levels of serum NT-proBNP, ANP, and BNP to improve heart failure. Together, YXT can inhibit cardiac muscle hypertrophy and fibrosis in rats and improve myocardial ultrastructure and serum IL-1ß, IL-6, and TNF-α levels. These effects are achieved by inhibiting the expressions of NF-κB and PKC. Conclusion: YXT regulates the TMAO/PKC/NF-κB signaling pathway in heart failure.

Trimethylamine-N-oxide aggravated the sympathetic excitation in D-galactose induced aging rats by down-regulating P2Y12 receptor in microglia.

This study aimed to determine whether trimethylamine N-oxide (TMAO) was involved in sympathetic activation in aging and the underlying mechanisms. Our hypothesis is TMAO reduces P2Y12 receptor (P2Y12R) and induces microglia-mediated inflammation in the paraventricular nucleus (PVN), then leading to sympathetic activation in aging. This study involved 18 young adults and 16 old adults. Aging rats were established by injecting D-galactose (D-gal, 200 mg/kg/d) subcutaneously for 12 weeks. TMAO (120 mg/kg/d) or 1% 3, 3-dimethyl-l-butanol (DMB) was administrated via drinking water for 12 weeks to investigate their effects on neuroinflammation and sympathetic activation in aging rats. Plasma TMAO, NE and IL-1ß levels were higher in old adults than in young adults. In addition, standard deviation of all normal to normal intervals (SDNN) and standard deviation of the average of normal to normal intervals (SDANN) were lower in old adults and negatively correlated with TMAO, indicating sympathetic activation in old adults, which is associated with an increase in TMAO levels. Treatment of rats with D-gal showed increased senescence-associated protein levels and microglia-mediated inflammation, as well as decreased P2Y12R protein levels in PVN. Plasma TMAO, NE and IL-1ß levels were increased, accompanied by enhanced renal sympathetic nerve activity (RSNA). While TMAO treatment exacerbated the above phenomenon, DMB mitigated it. These findings suggest that TMAO contributes to sympathetic hyperactivity in aging by downregulating P2Y12R in microglia and increasing inflammation in the PVN. These results may provide promising new target for the prevention and treatment of aging and aging-related diseases.

Shizukaol C alleviates trimethylamine oxide-induced inflammation through activating Keap1-Nrf2-GSTpi pathway in vascular smooth muscle cell.

BACKGROUND: Cardiovascular disease is one of the main causes of global mortality, and there is an urgent need for effective treatment strategies. Gut microbiota-dependent metabolite trimethylamine-N-oxide (TMAO) promotes the development of cardiovascular diseases, and shizukaol C, a natural sesquiterpene isolated from Chloranthus multistachys with various biological activities, might exhibit beneficial role in preventing TMAO-induced vascular inflammation. PURPOSE: The purpose of this study was to investigate the anti-inflammatory effects and the underlying mechanisms of shizukaol C on TMAO-induced vascular inflammation. METHODS: The effect and underlying mechanism of shizukaol C on TMAO-induced adhesion molecules expression, bone marrow-derived macrophages (BMDM) adhesion to VSMC were evaluated by western blot, cell adhesion assay, co-immunoprecipitation, immunofluorescence assay, and quantitative Real-Time PCR, respectively. To verify the role of shizukaol C in vivo, TMAO-induced vascular inflammation model were established using guidewire-induced injury on mice carotid artery. Changes in the intima area and the expression of GSTpi, VCAM-1, CD68 were examined using haematoxylin-eosin staining, and immunofluorescence assay. RESULTS: Our data demonstrated that shizukaol C significantly suppressed TMAO-induced adhesion molecule expression and the bone marrow-derived macrophages (BMDM) adhesion in vascular smooth muscle cells (VSMC). Mechanically, shizukaol C inhibited TMAO-induced c-Jun N-terminal kinase (JNK)-nuclear factor-kappa B (NF-κB)/p65 activation, and the JNK inhibition was dependent on the shizukaol C-mediated glutathione-S-transferase pi (GSTpi) expression. By further molecular docking and protein-binding analysis, we demonstrated that shizukaol C directly binds to Keap1 to induce Nrf2 nuclear translocation and upregulated GSTpi expression. Consistently, our in vivo experiment showed that shizukaol C elevated the expression level of GSTpi in carotid arteries and alleviates TMAO-induced vascular inflammation. CONCLUSION: Shizukaol C exerts anti-inflammatory effects in TMAO-treated VSMC by targeting Keap1 and activating Nrf2-GSTpi signaling and resultantly inhibits the downstream JNK-NF-κB/p65 activation and VSMC adhesion, and alleviates TMAO-induced vascular inflammation in vivo, suggesting that shizukaol C may be a potential drug for treating TMAO-induced vascular diseases.

Gut microbiome and metabolomic profiles reveal the antiatherosclerotic effect of indole-3-carbinol in high-choline-fed ApoE-/- mice.

BACKGROUND: The metabolites produced from choline contribute to atherosclerosis (AS) pathogenesis, and the gut microbiota is redundantly essential for this process. Indole-3-carbinol (I3C), found in cruciferous vegetables such as broccoli, cabbage, cauliflower and brussels sprouts, helps prevent hyperlipidemia, maintain the gut microbiota balance, and decrease the production of trimethylamine-N-oxide (TMAO) from choline in the diet. PURPOSE: The objective of this research was to investigate the impact of I3C on choline-induced AS and to further elucidate the underlying mechanism involved. METHODS: AS models of high-choline-induced ApoE-/- mice and TMAO-promoted foamy macrophages were established to observe the effect of I3C on the formation of atherosclerotic plaques and foam cells and changes in AS-related indicators (including blood biochemical indicators, TMA, TMAO, SRA, and SRB1), and integrated analyses of the microbiome and metabolome were used to reveal the mechanism of action of I3C. RESULTS: We found that I3C inhibited high-choline-induced atheroma formation (50-100 mg/kg/d, in vivo) and slightly improved the lipid profile (15 mg/kg/d, in vivo). Moreover, I3C suppressed lipid influx at a concentration of 40 µmol/L in vitro, enhanced the diversity of the gut microbiota and the abundance of the phylum Verrucomicrobia, and consequently modified the gut microbial metabolites at a dosage of 50 mg/kg/d in the mice. Associative analyses based on microbiome and metabolomics revealed that 1-methyladenosine was a key modulator of the protective effect of I3C against AS in high-choline-induced ApoE-/- mice. CONCLUSION: These findings demonstrate for the first time that I3C ameliorates AS progression through remodeling of the gut microbiome and metabolomics, which paves the way for the possible therapeutic use of this vegetable-derived natural compound and may reduce the clinical severity of AS-related cardiovascular diseases.

Trimethylamine N-oxide impairs ß-cell function and glucose tolerance.

ß-Cell dysfunction and ß-cell loss are hallmarks of type 2 diabetes (T2D). Here, we found that trimethylamine N-oxide (TMAO) at a similar concentration to that found in diabetes could directly decrease glucose-stimulated insulin secretion (GSIS) in MIN6 cells and primary islets from mice or humans. Elevation of TMAO levels impairs GSIS, ß-cell proportion, and glucose tolerance in male C57BL/6 J mice. TMAO inhibits calcium transients through NLRP3 inflammasome-related cytokines and induced Serca2 loss, and a Serca2 agonist reversed the effect of TMAO on ß-cell function in vitro and in vivo. Additionally, long-term TMAO exposure promotes ß-cell ER stress, dedifferentiation, and apoptosis and inhibits ß-cell transcriptional identity. Inhibition of TMAO production improves ß-cell GSIS, ß-cell proportion, and glucose tolerance in both male db/db and choline diet-fed mice. These observations identify a role for TMAO in ß-cell dysfunction and maintenance, and inhibition of TMAO could be an approach for the treatment of T2D.

Tangeretin Mitigates Trimethylamine Oxide Induced Arterial Inflammation by Disrupting Choline-Trimethylamine Conversion through Specific Manipulation of Intestinal Microflora.

Previous studies have revealed the microbial metabolism of dietary choline in the gut, leading to its conversion into trimethylamine (TMA). Polymethoxyflavones (PMFs), exemplified by tangeretin, have shown efficacy in mitigating choline-induced cardiovascular inflammation. However, the specific mechanism by which these compounds exert their effects, particularly in modulating the gut microbiota, remains uncertain. This investigation focused on tangeretin, a representative PMFs, to explore its influence on the gut microbiota and the choline-TMA conversion process. Experimental results showed that tangeretin treatment significantly attenuated the population of CutC-active bacteria, particularly Clostridiaceae and Lactobacillus, induced by choline chloride in rat models. This inhibition led to a decreased efficiency in choline conversion to TMA, thereby ameliorating cardiovascular inflammation resulting from prolonged choline consumption. In conclusion, tangeretin's preventive effect against cardiovascular inflammation is intricately linked to its targeted modulation of TMA-producing bacterial activity.

Activation of free fatty acid receptors, FFAR1 and FFAR4, ameliorates ulcerative colitis by promote fatty acid metabolism and mediate macrophage polarization.

OBJECTIVE: To investigate the mechanism of action of fatty acid receptors, FFAR1 and FFAR4, on ulcerative colitis (UC) through fatty acid metabolism and macrophage polarization. METHODS: Dextran sulfate sodium (DSS)-induced mouse model of UC mice was used to evaluate the efficacy of FFAR1 (GW9508) and FFAR4 (GSK137647) agonists by analyzing body weight, colon length, disease activity index (DAI), and histological scores. Real-time PCR and immunofluorescence analysis were performed to quantify the levels of fatty acid metabolizing enzymes and macrophage makers. FFA-induced lipid accumulation in RAW264.7 cells was visualized by Oil Red O staining analysis, and cells were collected to detect macrophage polarization by flow cytometry. RESULTS: The combination of GW9508 and GSK137647 significantly improved DSS-induced UC symptoms, caused recovery in colon length, and decreased histological injury. GW9508 + GSK137647 treatment upregulated the expressions of CD206, lipid oxidation enzyme (CPT-1α) and anti-inflammatory cytokines (IL-4, IL-10, IL-13) but downregulated those of CD86, lipogenic enzymes (ACC1, FASN, SCD1), and pro-inflammatory cytokines (IL-1ß, IL-6, TNF-α). Combining the two agonists decreased FFA-induced lipid accumulation and increased CD206 expression in cell-based experiments. CONCLUSION: Activated FFAR1 and FFAR4 ameliorates DSS-induced UC by promoting fatty acid metabolism to reduce lipid accumulation and mediate M2 macrophage polarization.

TMAO promotes vascular endothelial cell pyroptosis via the LPEAT-mitophagy pathway.

Trimethylamine N-oxide (TMAO) is a novel risk factor for atherosclerosis, and its underlying regulatory mechanisms are under intensive investigation. Inflammation-related vascular endothelial damage is the major driver in atherogenic process. Pyroptosis, a type of proinflammatory programmed cell death, has been proved to promote the initiation and progression of atherosclerosis. In our study, we found that TMAO triggered endothelial cells excessive mitophagy, thereby facilitating pyroptosis. This process is mediated by the upexpression of phosphatidylethanolamine acyltransferase (LPEAT). These findings provide insights into TMAO-induced vascular endothelial cell damage and suggest that LPEAT may be a valuable target for the prevention and treatment of atherosclerosis.

Structurally different chemical chaperones show similar mechanical roles with independent molecular mechanisms.

Osmolytes are well known to protect the protein structure against different chemical and physical denaturants. Since their actions with protein surfaces are mechanistically complicated and context dependent, the underlying molecular mechanism is not fully understood. Here, we combined single-molecule magnetic tweezers and molecular dynamics (MD) simulation to explore the mechanical role of osmolytes from two different classes, trimethylamine N-oxide (TMAO) and trehalose, as mechanical stabilizers of protein structure. We observed that these osmolytes increase the protein L mechanical stability by decreasing unfolding kinetics while accelerating the refolding kinetics under force, eventually shifting the energy landscape toward the folded state. These osmolytes mechanically stabilize the protein L and plausibly guide them to more thermodynamically robust states. Finally, we observed that osmolyte-modulated protein folding increases mechanical work output up to twofold, allowing the protein to fold under a higher force regime and providing a significant implication for folding-induced structural stability in proteins.

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.

Gut microbiota metabolite TMAO promoted lipid deposition and fibrosis process via KRT17 in fatty liver cells in vitro.

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide but still lacks specific treatment modalities. The gut microbiota and its metabolites have been shown to be intimately involved in NAFLD development, participating in and regulating disease progression. Trimethylamine N-oxide (TMAO), a metabolite highly dependent on the gut microbiota, has been shown to play deleterious regulatory roles in cardiovascular disease, but the relationship between it and NAFLD lacks validation from basic experiments. This research applied TMAO intervention by constructing fatty liver cell models in vitro to observe its effect on fatty liver cells and potential key genes and performed siRNA interference on the gene to verify the action. The results showed that TMAO intervention promoted the appearance of more red-stained lipid droplets in Oil-red O staining results, increased triglyceride (TG) levels and increased mRNA levels of liver fibrosis-related genes, and also identified one of the key genes, keratin17 (KRT17) via transcriptomics. Following the reduction in its expression level, under the same treatment, there were decreased red-stained lipid droplets, decreased TG levels, decreased indicators of impaired liver function as well as decreased mRNA levels of liver fibrosis-related genes. In conclusion, the gut microbiota metabolite TMAO could promote lipid deposition and fibrosis process via the KRT17 gene in fatty liver cells in vitro.

Contractile effect of trimethylamine and trimethylamine-n-oxide on isolated human umbilical arteries.

BACKGROUND: The aim of this study is to investigate the effect of trimethylamine (TMA) and trimethylamine-n-oxide (TMAO) on the contractility of human umbilical artery and the possible mechanisms involved. METHODS: Vasoactive responses to TMA and TMAO on human umbilical artery rings were measured in isolated organ baths. Cumulative dose-response curves for TMA and TMAO were obtained before and after incubation with atropine, yohimbine, prazosin, indomethacin, verapamil, and Ca+2 -free Krebs-Henselite solution. RESULTS: Administration of cumulative TMA and TMAO resulted in dose-dependent contraction at concentrations ranging from 10 to 100 mM on human umbilical artery rings. TMA-induced contractions were more potent than TMAO-induced contractions (TMA: -logEC50 = 1.00 ± 0.02, TMAO: -logEC50 = 0.57 ± 0.02). Contraction responses to TMA were significantly lower in the presence of verapamil and in the absence of external Ca+2 (p < 0.001, p < 0.05, respectively). CONCLUSION: Our results showed that TMA and TMAO caused vasoconstriction in isolated human umbilical artery rings. Our findings also indicated that TMA but not TMAO-induced vasoconstriction was partially dependent on extracellular Ca2+ and calcium influx through L-type Ca2+ channels. Our results suggest that TMA and TMAO may have the potential to contribute to cardiovascular diseases through their direct effect on vascular contractility in human arteries.

Urea ameliorates trimethylamine N-oxide-Induced aggregation of intrinsically disordered α-casein protein: the other side of the urea-methylamine counteraction.

Trimethylamine N-oxide (TMAO) is generally accumulated by organisms and cells to cope with denaturing effects of urea/hydrodynamic pressure on proteins and can even reverse misfolded or aggregated proteins so as to sustain proteostasis. However, most of the work regarding this urea-TMAO counteraction has been performed on folded proteins. Compelling evidence of aggregation of intrinsically disordered proteins (IDPs) like tau, α-synuclein, amyloid ß etc., by TMAO and its potential to impact various protein processes in absence of stressing agents (such as urea) suggests that the contrary feature of interaction profiles of urea and TMAO maximizes their chances of offsetting the perturbing effects of each other. Recently, our lab observed that TMAO induces aggregation of α-casein, a model IDP. In this context, the present study, for the first time, evaluated urea for its potential to counteract the TMAO-induced aggregation of α-casein. It was observed that, at the biologically relevant ratios of 2:1 or 3:1 (urea:TMAO), urea was able to inhibit TMAO-induced aggregation of α-casein. However, urea did not reverse the effects of TMAO on α-casein. In addition to this, α-casein in presence of 1:1 and 2:1 urea:TMAO working ratios show aggregation-induced cytotoxic effect on HEK-293, Neuro2A and HCT-116 cell lines but not in presence of 3:1 working ratio, as there was no aggregation at all. The study infers that the accumulation of TMAO alone in the cells, in absence of stress (such as urea), might result in loss of conformational flexibility and aggregation of IDPs in TMAO accumulating organisms.Communicated by Ramaswamy H. Sarma.

A Free Fatty Acid Synthetic Agonist Accelerates Wound Healing and Improves Scar Quality in Mice.

BACKGROUND: Impaired wound healing is a health problem around the world, and the search for a novel product to repair wounded skin is a major topic in the field. GW9508 is a synthetic molecule described as a selective agonist of free fatty acid receptors (FFARs) 1 and 4, and there is evidence of its anti-inflammatory effects on several organs of the body. PURPOSE: Here, we aimed to evaluate the effects of topical GW9508 on wound healing in mice. RESEARCH DESIGN: First, we used bioinformatic methods to determine the expression of FFAR1 and FFAR4 mRNA in the skin from a human cell atlas assembled with single-cell transcriptomes. Next, we employed 6-week-old C57BL6J mice with 2 wounds inflicted in the back. The mice were randomly divided into 2 groups, a control group, which received topical vehicle, and a treatment group, which received GW9508, for 12 days. The wound was monitored by photographic documentation every 2 days, and samples were collected at day 6 and 12 post injury for RT-PCR, western blot and histology analyses. RESULTS: FFAR1 and FFAR4 mRNA are expressed in skin cells in similar amounts to those in other tissues. Topical GW9508 accelerated wound healing and decreased gene expression of IL-10 and metalloproteinase 9 on days 6 and 12 post injury. It increased the quantity of Collagen I and improved the organization of collagen fibres. Conclusions: Our results show that GW9508 could be an attractive drug treatment for wounded skin. Future studies need to be performed to assess the impact of GW9508 in chronic wound models.

Novel protein-repellent and antibacterial polymethyl methacrylate dental resin in water-aging for 6 months.

BACKGROUND: The present study aimed to develop a novel protein-repellent and antibacterial polymethyl methacrylate (PMMA) dental resin with 2-methacryloyloxyethyl phosphorylcholine (MPC) and quaternary ammonium dimethylaminohexadecyl methacrylate (DMAHDM), and to investigate the effects of water-aging for 6 months on the mechanical properties, protein adsorption, and antibacterial activity of the dental resin. METHODS: Four groups were tested: PMMA control; PMMA + 3% MPC; PMMA + 1.5% DMAHDM; and PMMA + 3% MPC + 1.5% DMADDM in acrylic resin powder. Specimens were water-aged for 1 d, 3 months, and 6 months at 37 ℃. Their mechanical properties were then measured using a three-point flexure test. Protein adsorption was measured using a micro bicinchoninic acid (BCA) method. A human saliva microcosm model was used to inoculate bacteria on water-aged specimens and to investigate the live/dead staining, metabolic activity of biofilms, and colony-forming units (CFUs). RESULTS: The flexural strength and elastic modulus showed a significant loss after 6 months of water-ageing for the PMMA control (mean ± SD; n = 10); in contrast, the new protein repellent and antibacterial PMMA resin showed no strength loss. The PMMA-MPC-DMAHDM-containing resin imparted a strong antibacterial effect by greatly reducing biofilm viability and metabolic activity. The biofilm CFU count was reduced by about two orders of magnitude (p < 0.05) compared with that of the PMMA resin control. The protein adsorption was 20% that of a commercial composite (p < 0.05). Furthermore, the PMMA-MPC-DMAHDM-containing resin exhibited a long-term antibacterial performance, with no significant difference between 1 d, 3 months and 6 months (p > 0.05). CONCLUSIONS: The flexural strength and elastic modulus of the PMMA-MPC-DMAHDM-containing resin were superior to those of the PMMA control after 6 months of water-ageing. The novel PMMA resin incorporating MPC and DMAHDM exhibited potent and lasting protein-repellent and antibacterial properties.

NMR-Based Metabolomic Analysis for the Effects of Trimethylamine N-Oxide Treatment on C2C12 Myoblasts under Oxidative Stress.

The gut microbial metabolite trimethylamine N-oxide (TMAO) has received increased attention due to its close relationship with cardiovascular disease and type 2 diabetes. In previous studies, TMAO has shown both harmful and beneficial effects on various tissues, but the underlying molecular mechanisms remain to be clarified. Here, we explored the effects of TMAO treatment on H2O2-impaired C2C12 myoblasts, analyzed metabolic changes and identified significantly altered metabolic pathways through nuclear magnetic resonance-based (NMR-based) metabolomic profiling. The results exhibit that TMAO treatment partly alleviated the H2O2-induced oxidative stress damage of cells and protected C2C12 myoblasts by improving cell viability, increasing cellular total superoxide dismutase capacity, improving the protein expression of catalase, and reducing the level of malondialdehyde. We further showed that H2O2 treatment decreased levels of branched-chain amino acids (isoleucine, leucine and valine) and several amino acids including alanine, glycine, threonine, phenylalanine and histidine, and increased the level of phosphocholine related to cell membrane structure, while the TMAO treatment partially reversed the changing trends of these metabolite levels by improving the integrity of the cell membranes. This study indicates that the TMAO treatment may be a promising strategy to alleviate oxidative stress damage in skeletal muscle.

Analysis of Protein-Protein Interactions Identifies NECTIN2 as a Target of N,N-Bis (5-Ethyl-2-hydroxybenzyl) Methylamine for Inhibition of Lung Cancer Metastasis.

BACKGROUND/AIM: Metastasis negatively affects the survival of lung cancer patients, however, relatively few compounds have potential in metastasis suppression. This study investigated the molecular targets of N,N-bis (5-ethyl-2-hydroxybenzyl) methylamine (EMD) for metastatic inhibition. MATERIALS AND METHODS: Proteins were analyzed by proteomic and bioinformatic analyses. Protein-protein interaction (PPI) networks were created with the Search Tool for the Retrieval of Interacting Genes. The Kyoto Encyclopedia of Genes and Genomes database and hub genes were used to determine dominant pathways. Immunofluorescence and western blot analyses validated the proteomic results and investigated signaling pathways in NCI-H23 lung cancer cells. RESULTS: A total of 1,751 proteins were common to the control, EMD and N,N-bis(5-methoxy-2-hydroxybenzyl) methylamine (MeMD) groups; 1,980 different proteins were categorized using metastatic capacity category and analyzed for unique proteins affected by EMD. Fifteen proteins were associated with cell adhesion and six with cell migration. Nectin cell adhesion molecule 2 (NECTIN2) was expressed in the control and MeMD-treated groups but not the EMD-treated group, suggesting NECTIN2 as an EMD target. PPI network showed association of NECTIN2 with proteins regulating cancer metastasis. Kyoto Encyclopedia of Genes and Genomes pathways revealed that NECTIN2 is an upstream target of cytoskeletal regulation via SRC signaling. Western blot and immunofluorescence analyses confirmed that EMD suppressed NECTIN2, and its downstream targets, including p-SRC (Y146 and Y527) and the epithelial-to-mesenchymal transition markers tight junction protein 1, vimentin, ß-catenin, snail family transcriptional repressor 1 (SNAI1), and SNAI2, while increasing E-cadherin. CONCLUSION: EMD suppressed NECTIN2-induced activation of EMT signaling. These data support the development of EMD to prevent metastasis of lung cancer.

Effects of thermal cycling on mechanical and antibacterial durability of bioactive low-shrinkage-stress nanocomposite.

OBJECTIVES: Recent studies developed low-shrinkage-stress composite with remineralizing and antibacterial properties to combat secondary caries and increase restoration longevity. However, their long-term durability in thermal cycling is unclear. The objectives of this study were to develop an antibacterial, remineralizing and low-shrinkage-stress composite, and to investigate its durability in thermal cycling for 20,000 cycles, equivalent to two years of clinical life. METHODS: The resin consisted of urethane dimethacrylate (UDMA) and triethylene glycol divinylbenzyl ether (TEG-DVBE). Composites were made with 5% dimethylaminohexadecyl methacrylate (DMAHDM) and 20% of nanoparticles of amorphous calcium phosphate (NACP). Composites were thermal cycled at 5°C and 55°C for 20,000 cycles. A human salivary biofilm model was used to evaluate antibiofilm activity before and after thermal cycling. RESULTS: After 20,000 cycles, the flexural strength of bioactive low-shrinkage-stress composite matched commercial control with no antibacterial activity (p > 0.05). Surface roughness was clinically acceptable at less than 0.2 µm. UV+NACP+DMAHDM composite reduced the total microorganisms, total streptococci, and mutans streptococci by 2-5 logs, compared to commercial composite. Biofilm lactic acid production was reduced by 11 folds. The antibacterial performance was maintained after thermal cycling, with no decrease after 20,000 cycles. CONCLUSIONS: Bioactive low-shrinkage-stress composite possessed good mechanical properties that matched commercial composite both before and after thermal cycling. The new composite had potent antibacterial activity, which was maintained and did not decrease after thermal cycling. CLINICAL SIGNIFICANCE: The new bioactive low-shrinkage-stress composite could reduce polymerization shrinkage stress and release calcium and phosphate ions, with good mechanical properties and strong antibacterial function that were durable after thermal cycling. These properties indicate great potential for inhibiting recurrent caries and increasing the restoration longevity.

PRMT5 critically mediates TMAO-induced inflammatory response in vascular smooth muscle cells.

A high plasma level of the choline-derived metabolite trimethylamine N-oxide (TMAO) is closely related to the development of cardiovascular disease. However, the underlying mechanism remains unclear. In the present study, we demonstrated that a positive correlation of protein arginine methyltransferase 5 (PRMT5) expression and TMAO-induced vascular inflammation, with upregulated vascular cell adhesion molecule-1 (VCAM-1) expression in primary rat and human vascular smooth muscle cells (VSMC) in vitro. Knockdown of PRMT5 suppressed VCAM-1 expression and the adhesion of primary bone marrow-derived macrophages to TMAO-stimulated VSMC. VSMC-specific PRMT5 knockout inhibited vascular inflammation with decreased expression of VCAM-1 in mice. We further identified that PRMT5 promoted VCAM-1 expression via symmetrical demethylation of Nuclear factor-κB p65 on arginine 30 (R30). Finally, we found that TMAO markedly induced the expression of nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) and production of reactive oxygen species, which contributed to PRMT5 expression and subsequent VCAM-1 expression. Collectively, our data provide novel evidence to establish a Nox4-PRMT5-VCAM-1 in mediating TMAO-induced VSMC inflammation. PRMT5 may be a potential target for the treatment of TMAO-induced vascular diseases.