Time dependent impact of copper oxide nanomaterials on the expression of genes associated with oxidative stress, metal binding, inflammation and mucus secretion in single and co-culture intestinal in vitro models

Sorbitol Destroyed Intestinal Microfold Cells (M Cells) Development through Inhibition of PDE4-Mediated RANKL Expression

Objective

Microfold cells (M cells) are specific intestinal epithelial cells for monitoring and transcytosis of antigens, microorganisms, and pathogens in the intestine. However, the mechanism for M-cell development remained elusive.

Materials and Methods

Real-time polymerase chain reaction, immunofluorescence, and western blotting were performed to analyze the effect of sorbitol-regulated M-cell differentiation in vivo and in vitro, and luciferase and chromatin Immunoprecipitation were used to reveal the mechanism through which sorbitol-modulated M-cell differentiation.

Results

Herein, in comparison to the mannitol group (control group), we found that intestinal M-cell development was inhibited in response to sorbitol treatment as evidenced by impaired enteroids accompanying with decreased early differentiation marker Annexin 5, Marcksl1, Spib, sox8, and mature M-cell marker glycoprotein 2 expression, which was attributed to downregulation of receptor activator of nuclear factor kappa-В ligand (RANKL) expression in vivo and in vitro. Mechanically, in the M-cell model, sorbitol stimulation caused a significant upregulation of phosphodiesterase 4 (PDE4) phosphorylation, leading to decreased protein kinase A (PKA)/cAMP-response element binding protein (CREB) activation, which further resulted in CREB retention in cytosolic and attenuated CREB binds to RANKL promoter to inhibit RANKL expression. Interestingly, endogenous PKA interacted with CREB, and this interaction was destroyed by sorbitol stimulation. Most importantly, inhibition of PDE4 by dipyridamole could rescue the inhibitory effect of sorbitol on intestinal enteroids and M-cell differentiation and mature in vivo and in vitro.

Conclusion

These findings suggested that sorbitol suppressed intestinal enteroids and M-cell differentiation and matured through PDE4-mediated RANKL expression; targeting to inhibit PDE4 was sufficient to induce M-cell development.

The Involvement of Lactic Acid Bacteria and Their Exopolysaccharides in the Biosorption and Detoxication of Heavy Metals in the Gut

Heavy metal pollution has become one of the most important global environmental issues. The human health risk posed by heavy metals encountered through the food chain and occupational and environmental exposure is increasing, resulting in a series of serious diseases. Ingested heavy metals might disturb the function of the gut barrier and cause toxicity to organs or tissues in other sites of the body. Probiotics, including some lactic acid bacteria (LAB), can be used as an alternative strategy to detoxify heavy metals in the host body due to their safety and effectiveness. Exopolysaccharides (EPS) produced by LAB possess varied chemical structures and functional properties and take part in the adsorption of heavy metals via keeping the producing cells vigorous. The main objective of this paper was to summarize the roles of LAB and their EPS in the adsorption and detoxification of heavy metals in the gut. Accumulated evidence has demonstrated that microbial EPS play a pivotal role in heavy metal biosorption. Specifically, EPS-producing LAB have been reported to show superior absorption, tolerance, and efficient abatement of the toxicity of heavy metals in vitro and/or in vivo to non-EPS-producing species. The mechanisms underlying EPS-metal binding are mainly related to the negatively charged acidic groups and unique steric structure on the surface of EPS. However, whether the enriched heavy metals on the bacterial cell surface increase toxicity to local mammal cells or tissues in the intestine and whether they are released during excretion remain to be elucidated.

Mucin2 regulated by Ho1/p38/IL-10 axis plays a protective role in polystyrene nanoplastics-mediated intestinal toxicity

Micro/nano-plastics (MPs/NPs) are a newly discovered environmental pollutant that can be ingested by humans through food and drinking water. In this study we evaluated the impact of MPs/NPs on the intestinal barrier and its mechanism. Doses of MPs/NPs were used to treat Caco-2/HT29-MTX in-vitro model and in-vivo model. In in-vitro model, 20 nm polystyrene nanoplastics (PS-NPs) had higher cytotoxicity than larger particles (200 nm and 2000 nm), and led to the increase of the permeability along with the decreased expression of tight junction proteins. Intriguingly, 20 nm PS-NPs elevated the expression of MUC2 simultaneously. Further studies revealed that PS-NPs increased the expression of HO1 through ROS generation, and then activated p38 to elevate IL-10 secretion in Caco-2 cell. The IL-10 secreted by Caco-2 cell promoted the expression of MUC2 in HT29-MTX cell through STAT1/3. Elevated MUC2 expression alleviates the cytotoxicity of PS-NPs. Besides, increased intestinal permeability and up-regulation of MUC2 through Ho1/p38/IL-10 pathway was also observed in 20 nm PS-NPs treated mouse model. In conclusion, PS-NPs can induce the intestinal toxicity and result in the increased adaptive expression of MUC2 to resist this adverse effect. People with inadequate mucin expression need to pay more attention to the toxicity of PS-NPs. This study provided a valuable insight for clarifying the mechanism and potential risk of intestinal toxicity induced by nanoplastics.

Effects of wildfire ashes on aquatic invertebrates: First molecular approach on Chironomus riparius larvae

The wildfire magnification in recent years has raised increasing concern about their adverse impacts on the environment. Wildfires are recognized as an important source of diffuse pollution for the nearby aquatic systems being potentially toxic to aquatic life. Albeit previous studies with wildfire runoff/ashes observed effects in aquatic organisms, to date, different severity origins of ashes and their impact at the sub-organismal level on aquatic biota have not been assessed. In this work, the molecular response of Chironomus riparius exposed to wildfire with low (LS) and high (HS) severity ashes from burnt Pine plantations was evaluated by employing an array of 42 genes related to crucial metabolic pathways by Real time-PCR. IV instar larvae were exposed for 72 h to aqueous extract of ashes (12.5 %, 25 %, 50 %, 75 % and 100 %) prepared from LS and HS ashes. Mn, Zn, and Pb were the metals found at highest concentration in both ash extracts, for HS notable Cd, Mn and Cr presence. From the 42 genes studied only 4 were not altered (22 genes modulated their response by LS and 38 genes in the case of HS) showing the opposite response at 100% with downregulated by LS and upregulated by HS. The 12.5 %, 25 %, 100 % HS and 25 % LS were the main modulators, confirmed by the integrative biomarkers response (IBR). Remarkable genotoxicity was generated by ashes even activating the apoptosis response, and endocrine disruption observed could modify the development. Moreover, detoxification and stress response were strongly activated, limiting the organism's future response to external aggressions. The employment of this novelty approach with molecular tools act as early alarm signal preventing greater damages. Overall, wildfire ashes showed to be a significant environmental disruptor to C. riparius even at lower concentration and the short exposure time employed, emphasizing the strong impact of wildfires on aquatic systems.

New insights into the interaction between duodenal toxicity and microbiota disorder under copper exposure in chicken: Involving in endoplasmic reticulum stress and mitochondrial toxicity

Copper (Cu) has been widely used in industrial agricultural production, but excess use can lead to toxic effect on host physiology, which poses a threaten to public hygiene. However, the relationship between gut microbiota and Cu-induced intestinal toxicity is unclear. Here, we identified that intestinal flora disturbance was related to duodenal toxicity under Cu exposure. We found that excess Cu disturbed gut microbiota homeostasis, resulting in Cu accumulation and intestinal damage. In addition, Cu considerably increased intestinal permeability by reducing expression of tight junction proteins (Claudlin-1, Occludin, and ZO-1). Meanwhile, Cu could induce endoplasmic reticulum stress, mitophagy, and mitochondria-mediated apoptosis in the duodenum, with the evidence by the elevated levels of GRP78, GRP94, LC3Ⅱ/LC3Ⅰ and Caspase-3 protein expression. Correlation analysis showed that Melainabacteria was closely related to tight junction proteins and endoplasmic reticulum stress of duodenum, indicating that disturbance of intestinal flora may aggravate the toxic effect of Cu. Therefore, our results suggest that the destruction of intestinal flora induced by excessive Cu may further lead to intestinal barrier damage, ultimately leading to endoplasmic reticulum stress, mitophagy and apoptosis. This research provides a new insight into interpretation of the interrelationship between microbiota disorder and duodenal toxicity under Cu exposure.

β-Carotene extracted from Blakeslea trispora attenuates oxidative stress, inflammatory, hepatic injury and immune damage induced by copper sulfate in zebrafish (Danio rerio)

β-Carotene, as a kind of potent antioxidant compounds, has gained extensive attention. Blakeslea trispora, a filiform aerobic fungus, has been proposed as a natural source of β-carotene for commercial exploitation. However, it has not yet been investigated whether β-carotene extracted from Blakeslea trispora can attenuate oxidative stress, inflammatory, liver injury and immune damage of zebrafish (Danio rerio) exposed to copper sulfate (CuSO₄). In this study, we evaluated the effects of β-carotene on migration of GFP-labeled neutrophils, histological changes of liver, markers of oxidative, inflammatory cytokines and transaminase analysis, as well as the expression and activities of apoptosis, immune-related certain genes in zebrafish treated with different concentrations of β-carotene (0, 10, 20, 40 μg/mL) after exposure to CuSO₄. The results indicated that β-carotene reduced migration of neutrophils and released liver damage. What's more, β-carotene was found to reduce the index levels of oxidative stress response (HMOX-1, reactive oxygen species (ROS), NADPH, MDA), inflammatory factors (interleukine-1β (IL-1β), interleukine-6 (IL-6), interleukine-8 (IL-8), tumor necrosis factor-α (TNF-α)), liver function protein (AST, ALT) which increased by CuSO₄. β-Carotene also promoted the activities of SOD, GSH-Px, ACP, AKP and LZM and increased the protein of immune-related factors, IgM and IFN-γ after exposure to CuSO₄. Thus, our results demonstrate that β-carotene has an antioxidant, anti-inflammatory and hepatoprotective activity and participation in immunoregulation.

Nanoparticles Isolated From Porcine Bone Soup Ameliorated Dextran Sulfate Sodium-Induced Colitis and Regulated Gut Microbiota in Mice

Daily foods contain a great number of self-assembled nanoparticles (NPs) which were incidentally produced during food processing. These food incidental NPs can directly access the human gastrointestinal tract in high frequency and large quantities. Limited reports were focused on whether and how these food incidental NPs affected the gastrointestinal tissues and gut microbiota. In the present study, bone soup and its NPs both significantly ameliorated colitis symptoms in dextran sulfate sodium (DSS)-induced mice and inhibited the release of pro-inflammatory cytokines. They also restored intestinal microbiota dysbiosis by improving the diversity and richness of intestinal microbiota and regulating community composition, such as a remarkable increase in Muribaculaceae, Alistipes, and Alloprevotella, and a decrease in Helicobacter. Moreover, the correlation analysis showed that pro-inflammatory cytokines were negatively correlated with Muribaculaceae, Alloprevotella, and Alistipes, but positively correlated with Helicobacter. These findings suggest that the food incidental NPs can influence human health through regulating the inflammation of the gastrointestinal tissues and the gut microbiota.

Grouping Hypotheses and an Integrated Approach to Testing and Assessment of Nanomaterials Following Oral Ingestion

The risk assessment of ingested nanomaterials (NMs) is an important issue. Here we present nine integrated approaches to testing and assessment (IATAs) to group ingested NMs following predefined hypotheses. The IATAs are structured as decision trees and tiered testing strategies for each decision node to support a grouping decision. Implications (e.g., regulatory or precautionary) per group are indicated. IATAs integrate information on durability and biopersistence (dissolution kinetics) to specific hazard endpoints, e.g., inflammation and genotoxicity, which are possibly indicative of toxicity. Based on IATAs, groups of similar nanoforms (NFs) of a NM can be formed, such as very slow dissolving, highly biopersistent and systemically toxic NFs. Reference NMs (ZnO, SiO2 and TiO2) along with related NFs are applied as case studies to testing the oral IATAs. Results based on the Tier 1 level suggest a hierarchy of biodurability and biopersistence of TiO2 > SiO2 > ZnO, and are confirmed by in vivo data (Tier 3 level). Interestingly, our analysis suggests that TiO2 and SiO2 NFs are able to induce both local and systemic toxicity along with microbiota dysbiosis and can be grouped according to the tested fate and hazard descriptors. This supports that the decision nodes of the oral IATAs are suitable for classification and assessment of the toxicity of NFs.