Gut Microbiota-Derived Tryptophan Metabolite Indole-3-aldehyde Ameliorates Aortic Dissection.

Tryptophan, an essential dietary amino acid, is metabolized into various metabolites within both gut microbiota and tissue cells. These metabolites have demonstrated potential associations with panvascular diseases. However, the specific relationship between tryptophan metabolism, particularly Indole-3-aldehyde (3-IAId), and the occurrence of aortic dissection (AD) remains unclear. 3-IAId showed an inverse association with advanced atherosclerosis, a risk factor for AD. In this study, we employed a well-established ß-aminopropionitrile monofumarate (BAPN)-induced AD murine model to investigate the impact of 3-IAId treatment on the progression of AD. Our results reveal compelling evidence that the administration of 3-IAId significantly mitigated aortic dissection and rupture rates (BAPN + 3-IAId vs. BAPN, 45% vs. 90%) and led to a notable reduction in mortality rates (BAPN + 3-IAId vs. BAPN, 20% vs. 55%). Furthermore, our study elucidates that 3-IAId exerts its beneficial effects by inhibiting the phenotype transition of vascular smooth muscle cells (VSMCs) from a contractile to a synthetic state. It also mitigates extracellular matrix degradation, attenuates macrophage infiltration, and suppresses the expression of inflammatory cytokines, collectively contributing to the attenuation of AD development. Our findings underscore the potential of 3-IAId as a promising intervention strategy for the prevention of thoracic aortic dissection, thus providing valuable insights into the realm of vascular disease management.

Oxidative compensation mechanism of Fe-S synergetic inhibition of Cd activity in paddy field during flooding and drainage.

It is known that the transformation of Fe and S forms in soil affects the migration and activity of Cd, but the coordinated regulation of Cd activity by Fe and S under different redox conditions is still unclear. Here, Diffusive gradients in thin films (DGT), an in-situ monitoring technique, is used to explore the difference of the regulation of Cd activity in paddy fields with ferrihydrite (FH) and ferrihydrite coprecipitated by sulfate (FH-S) under the flooding and drainage conditions. The addition of FH-S and FH significantly reduced the activity of Cd (Dissolved, Exchanged, and CDGT-Cd). Compared with pure FH, the adsorption extent of Cd in FH was enhanced by increasing concentrations of SO42- (i.e., S/Fe ratio), which is attributed to the decrease in the crystallinity of FH by sulfate. During soil flooding, the addition of FH-S promoted the production of metal sulfide (CdS and FeS/FeS2). The activity of Cd increased after drainage, while the FH-S treatment groups delayed the release of Cd. After 30 days of drainage, the concentration of Cd in FH-S treatment groups decreased by 28.9-44.1 % compared with the control group. The fresh FeS/FeS2 is not the main adsorbent for fixing Cd, and due to the existence of oxidation compensation mechanism, the preferential oxidation of FeS/FeS2 delays the release of Cd in the drainage stage. Our study shed new light on the mechanism of Fe-S synergistic regulation of Cd and remediation of Cd-contaminated soils.

Mechanisms of S cooperating with Fe and Mn to regulate the conversion of Cd and Cu during soil redox process revealed by LDHs-DGT technology.

The activity changes of Cd and Cu in paddy field were strongly influenced by the transformation of S, Fe and Mn species. However, in the process of soil redox, how S cooperates with Fe/Mn to regulate the law and mechanism of Cd and Cu speciation transformation still needs to be studied. In this study, we used DGT technology based on layer double hydroxides (LDHs) combined with pore water sampling to investigate soil redox changes, rice growth, and the effects of different forms of sulfur (S0, SO42-) on soil Cd and Cu activities. The results showed that the concentrations of CDGT-Cd and Cu in the soil decreased rapidly in the anaerobic stage, but increased slowly in the oxidative stage. Multiple regression analysis showed that the changes of Cu and Cd concentrations mainly depended on the changes of Fe/Mn morphology. Sulfur treatment promoted the dissolution of Fe/Mn oxides in the short term (<48 h), and the activities of CDGT-Fe, Mn, and Cd increased simultaneously, but CDGT-Cu was not affected. However, after long-term anaerobic conditions (>10 d), sulfur addition reduced the activities of CDGT-Cd and Cu, and decreased the uptake of Cd and Cu by rice. During sulfate reduction, the sulfur addition treatment group resulted in a 24.5-50.2 % decrease in CDGT-Fe, indicating that sulfur addition may delay the release of Cd and Cu after rice planting by promoting the formation of FeS/FeS2. In addition, in the anaerobic stage, Cu formed sulfide before Cd and was fixed, and the higher thermodynamic stability of CuS would promote the dissolution of CdS in the oxidation stage. Overall, soil flooding with sulfur to enhance the generation of metal sulfides and secondary iron ores provides an opportunity to use sulfur as an environmentally friendly modifier to coordinate Fe, Mn to improve heavy metal-contaminated soils.

Alpha-lipoic acid protects against aortic aneurysm and dissection by improving vascular smooth muscle cell function.

Alpha-Lipoic acid (ALA) plays a protective role in a variety of vascular diseases, however, its effect on aortic aneurysm and dissection (AAD) has not been reported. In this study, we found that Alpha-Lipoic Acid treatment significantly improved the AAD and AAA development, which was demonstrated by ameliorated aneurysmal dilation, decreased aortic dissection and aneurysm incidence, improved aortic morphology and inhibited elastin degradation. ALA blunted extra-cellular matrix degradation, vascular smooth muscle cell (VSMC) loss and phenotype transformation. Moreover, the protective effect of ALA on VSMCs may be related to the amelioration of mitochondrial dysfunction. In conclusion, our study revealed that ALA exerts inhibitory effects against progression of AAD, thus suggesting that ALA may be a novel therapeutic molecule for AAD.

Effect of foliar and root exposure to polymethyl methacrylate microplastics on biochemistry, ultrastructure, and arsenic accumulation in Brassica campestris L.

Despite the serious risk of microplastic pollution in the roots and leaves of crops, the phytotoxicity of microplastics (introduced via different exposure routes) in leafy vegetables remain insufficiently understood. Here, the effects of the root and foliar exposure of polymethyl methacrylate microplastic (PMMAMPs) on phytotoxicity, As accumulation, and subcellular distribution were investigated in rapeseed (Brassica campestris L). The relative chlorophyll content under PMMAMPs treatment decreased with time, and the 0.05 g L-1 root exposure decreased it significantly (by 9.97-20.48%, P < 0.05). In addition, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX) activities in rapeseed were more sensitive to PMMAMPs introduced through root exposure than through foliar exposure. There was dose-dependent ultrastructural damage, and root exposure had a greater impact than foliar exposure on root tip cells and chloroplasts. PMMAMPs entered the shoots and roots of rapeseed through root exposure. Under foliar exposure, PMMAMPs promoted As accumulation in rapeseed by up to 75.6% in shoots and 68.2% in roots compared to that under control (CK). As content in cell wall under PMMAMP treatments was 3.6-5.3 times higher than that of CK, as indicated by subcellular component results. In general, root exposure to PMMAMPs resulted in a stronger physiological impact and foliar exposure led to increased As accumulation in rapeseed.

How do controlled-release fertilizer coated microplastics dynamically affect Cd availability by regulating Fe species and DOC content in soil?

Microplastics (MPs) affect the accumulation of heavy metals by regulating the soil environment. However, studies on the dynamic effects of microplastics on the available states of heavy metals in soil are lacking. In particular, how controlled-release fertilizer coated microplastics can synergistically change the avsilable states of heavy metals in soil by affecting soil physical and chemical properties and microbial community structure is still lacking. The dynamic effect of polyurethane (PU) MPs on the effective state of soil cadmium (Cd; DGTCd), at different particle sizes and concentrations, was studied in situ by diffusive gradient in thin-films (DGT) for the first time. The bioavailability, soil chemical properties, and microbial effects of PU MPs on Cd depend on PU particle size and concentration; high-concentration (1 %) PU MPs cause a significant increase in DGT-Cd concentration. The addition of PU MPs decreased soil pH and dissolved organic carbon (DOC), while increasing the absolute zeta value, Fe(II) and Mn(II), in a manner dependent on particle size, concentration, and culture time. Correlation analysis combined with path analysis showed that PU MPs affected the effective state of Cd by changing soil properties, among which Fe(II) content and DOC were important factors controlling the activation of Cd. Meanwhile, changes in soil properties and heavy metal availability correlated significantly with microbial community composition, suggesting that PU MPs may indirectly impact heavy metal activity by affecting microorganisms and functional genes associated with C and Fe cycling. Therefore, when the concentration of PU MPs is higher than 1 %, we should strengthen ecological risk prevention and control of the compound pollution of controlled-release fertilizer coated microplastics and heavy metals in farmland soil.

Flooding-drainage regulate the availability and mobility process of Fe, Mn, Cd, and As at paddy soil.

Speciation changes in Fe and Mn during the soil flooding-drainage process strongly affect the Cd and As bioavailability in paddy soils. However, owing to a lack of in-situ dynamic monitoring technology, the regularity and mechanism of synergetic changes in Fe, Mn, Cd, and As in paddy soils have not been sufficiently studied. Diffusive gradients in thin films (DGT) were used to investigate the dissolution/transformation process of FeMn oxides and their effects on the bioavailability of Cd and As in three contaminated paddy fields that underwent incubated flooding for 40 d followed by a 20 d oxidation period. In-situ monitoring showed that the labile Cd concentrations decreased rapidly upon flooding but bioavailability of As increased significantly, with As and Cd concentrations largely depending upon Fe (II) content. We discovered that the transformation pathway of Iron Oxide-LDH (FeII-FeIII)-Goethite was the key process in reducing the activity of soil Cd. A higher Mn/Fe ratio and lower organic matter content delayed the Fe reduction process, which subsequently delayed Cd immobilization. Mobilization of Cd upon soil drainage was caused by a decrease in soil pH resulting in the release of Cd from secondary minerals.

Single and joint toxicity of polymethyl methacrylate microplastics and As (V) on rapeseed (Brassia campestris L.).

Most microplastics and arsenic (As) have been released into farmland via industrial and agricultural activities, posing a potential threat to crop growth and food safety. Thus far, few studies have focused on the phytoxicity of microplastics and As to leafy vegetable. In this study, we evaluated the single and combined toxicological effects of polymethyl methacrylate (PMMA) and As(V) on rapeseed (Brassia campestris L.). Single treatments of two sizes of PMMA particles, namely PMMA nano-plastics (PMMANPs) and PMMA micro-plastics (PMMAMPs) and As(V) significantly (P < 0.05) inhibited the germination index (GI) of rapeseed. The IC50 indicates that PMMANPs were more toxic than PMMAMPs. Combine-pollution experiments demonstrated that the GI, biomass, root length, and sprout length of the rapeseed under the combined treatment were lower than those subjected to As(V) or PMMANPs single treatment. Analysis of variance showed that the interaction effects of PMMANPs and As(V) for GI and root length were significant, and there was synergistic interaction between PMMANPs and As(V) on rapeseed germination. PMMANPs promoted the accumulation of As in sprouts under high As(V) concentrations (40 and 60 mg/L). The activities of lipase in rapeseed generally increased under single and combined treatments of As(V) and PMMANPs, and while α-amylase activities first increased and then decreased with the increase of PMMANPs. It appears that the combined stress of microplastics and As(V) exhibited synergistic interaction on the growth of rapeseed.

Differences and mechanism of dynamic changes of Cd activity regulated by polymorphous sulfur in paddy soil.

Sulfur (S) can decrease the bioavailability of Cd in paddy soil, and therefore reduce Cd uptake by rice. However, the dynamic influence mechanism of different forms of sulfur on the bioavailability of cadmium in soil has not been systematically studied. In this study, we used Diffusive gradients in thin films (DGT) technology and soil pore water sampling technology to investigate the effects of different types of S application on the bioavailability of Cd. The three forms of S are elemental sulfur (S0), sodium sulfate (SO42-), and mercapto-grafted palygorskite (MP), which have been treated in six ways according to CK, SL, SH, SO42L, SO42H, MP (L and H are the low and high levels of treatments). The results showed that soluble and labile Cd concentration was quickly fixed after flooding but activated after rice transplantation. Both MP and SL treatments increased the content of dissolved organic carbon (DOC) and significantly reduced the accumulation of Cd in roots and grains. The Cd content of roots treated with MP was only 0.50 mg kg-1, which was 77.6% lower than the Cd content in CK (2.22 mg kg-1). S promotes the reduction and dissolution of Fe, and the formation of FeS/FeS2 is also one of the reasons for the low bioavailability of Cd, while the SH treatment has a greater effect on lowering pH, so the effect of fixing Cd is not obvious. In addition, SO42- treatment delays the soil reduction process, so it cannot effectively fix Cd. At the stage of rice maturity, dissolved Cd increased in S treatment, but MP treatment did not have this phenomenon. The possible reason was the consumption of DOC or the oxidation of CdS which caused Cd to enter the soil solution. Taken together, Fe-S play a critical role in controlling the mobilization of Cd in paddy systems.

Inhibition effect of sulfur on Cd activity in soil-rice system and its mechanism.

Sulfur (S) can regulate the mobility of cadmium (Cd) in soil and reduce Cd uptake by rice. However, the mechanism of how S affects soil properties and then regulates Cd mobility in rice growth through multiple factors is unclear. Diffusive gradients in thin films (DGT) and other in situ detection techniques, were innovatively used in this study. The effect of S on soil Cd mobility under flooded condition was analyzed in situ and the related mechanism was discussed. The results showed that the addition of S increased the level of dissolved organic oxygen (DOC), increased the concentration of Fe(Ⅱ) and S(-Ⅱ), and decreased the concentration of labile Cd in soil. Multiple regression analysis showed that Fe(Ⅱ), S(-Ⅱ), DOC were negatively correlated with labile Cd. S promoted the reduction of sulfate and iron and accelerated the formation of CdS and iron complexed Cd. The results of path analysis showed that the synergistic effect of S and Fe significantly inhibited the mobility of Cd. In particular, the mobility of Cd at tillering stage was greatly affected by S and Fe. Mercapto-palygorskite can effectively increase the concentration of Fe(Ⅱ),S(-Ⅱ) and DOC in soil, and reduce the harm of Cd to rice better than S0 and Na2SO4.