Butyrate Prevents the Pathogenic Anemia-Inflammation Circuit by Facilitating Macrophage Iron Export.

Most patients with inflammatory bowel disease (IBD) develop anemia, which is attributed to the dysregulation of iron metabolism. Reciprocally, impaired iron homeostasis also aggravates inflammation. How this iron-mediated, pathogenic anemia-inflammation crosstalk is regulated in the gut remains elusive. Herein, it is for the first time revealed that anemic IBD patients exhibit impaired production of short-chain fatty acids (SCFAs), particularly butyrate. Butyrate supplementation restores iron metabolism in multiple anemia models. Mechanistically, butyrate upregulates ferroportin (FPN) expression in macrophages by reducing the enrichment of histone deacetylase (HDAC) at the Slc40a1 promoter, thereby facilitating iron export. By preventing iron sequestration, butyrate not only mitigates colitis-induced anemia but also reduces TNF-α production in macrophages. Consistently, macrophage-conditional FPN knockout mice exhibit more severe anemia and inflammation. Finally, it is revealed that macrophage iron overload impairs the therapeutic effectiveness of anti-TNF-α antibodies in colitis, which can be reversed by butyrate supplementation. Hence, this study uncovers the pivotal role of butyrate in preventing the pathogenic circuit between anemia and inflammation.

Butyrate reverses ferroptosis resistance in colorectal cancer by inducing c-Fos-dependent xCT suppression.

Ferroptosis has emerged to be a promising approach in cancer therapies; however, colorectal cancer (CRC) is relatively insensitive to ferroptosis. Exactly how the gut microenvironment impacts the ferroptotic sensitivity of CRC remains unknown. Herein, by performing metabolomics, we discovered that butyrate concentrations were significantly decreased in CRC patients. Butyrate supplementation sensitized CRC mice to ferroptosis induction, showing great in vivo translatability. Particularly, butyrate treatment reduced ferroptotic resistance of cancer stem cells. Mechanistically, butyrate inhibited xCT expression and xCT-dependent glutathione synthesis. Moreover, we identified c-Fos as a novel xCT suppressor, and further elucidated that butyrate induced c-Fos expression via disrupting class I HDAC activity. In CRC patients, butyrate negatively correlated with tumor xCT expression and positively correlated with c-Fos expression. Finally, butyrate was found to boost the pro-ferroptotic function of oxaliplatin (OXA). Immunohistochemistry data showed that OXA non-responders exhibited higher xCT expression compared to OXA responders. Hence, butyrate supplementation is a promising approach to break the ferroptosis resistance in CRC.

Isosteviol attenuates DSS-induced colitis by maintaining intestinal barrier function through PDK1/AKT/NF-κB signaling pathway.

Inflammatory bowel diseases (IBD) are chronic debilitating inflammatory disorders of the gastrointestinal tract that is characterized by intestinal epithelial barrier dysfunction and excessive activation of the mucosal immune system. Isosteviol (IS) has been reported to possess anti-inflammatory properties. In this study, we aimed to investigate effects and mechanisms of IS against intestinal inflammation. C57BL/6 mice were randomly divided into Sham, IS, dextran sodium sulfate (DSS), and DSS + IS groups. In vivo colitis model was established using 3.0 % DSS. In vitro, tumor necrosis factor-α (TNF-α)-treated Caco-2 cells were used as an inflammatory model. Clinical characteristics, histological performance, proinflammatory cytokine expression, and intestinal barrier function were measured. In addition, activation of the pyruvate dehydrogenase kinase 1/protein kinase B/nuclear factor-κB (PDK1/AKT/NF-κB) signaling pathway was determined by western blotting and quantitative polymerase chain reaction. The results showed that IS mitigated DSS-induced colitis by reducing body weight loss, colonic shortening, and disease activity index score, and by inhibiting expressions of proinflammatory cytokines IL-1ß, IL-6, and TNF-α. IS restored impaired barrier function by regulating tight junctions and intestinal epithelial permeability. Furthermore, we found that IS ameliorated intestinal barrier injury by regulating PDK1/AKT/NF-κB signaling pathway. In conclusion, our results demonstrate that IS attenuates experimental colitis by preserving intestinal barrier function, probably mediated by PDK1/AKT/NF-κB signaling pathway. These findings highlight the potential of IS as a therapeutic agent for IBD.

Mannose metabolism normalizes gut homeostasis by blocking the TNF-α-mediated proinflammatory circuit.

Mannose is a naturally occurring sugar widely consumed in the daily diet; however, mechanistic insights into how mannose metabolism affects intestinal inflammation remain lacking. Herein, we reported that mannose supplementation ameliorated colitis development and promoted colitis recovery. Macrophage-secreted inflammatory cytokines, particularly TNF-α, induced pathological endoplasmic reticulum stress (ERS) in intestinal epithelial cells (IECs), which was prevented by mannose via normalization of protein N-glycosylation. By preserving epithelial integrity, mannose reduced the inflammatory activation of colonic macrophages. On the other hand, mannose directly suppressed macrophage TNF-α production translationally by reducing the glyceraldehyde 3-phosphate level, thus promoting GAPDH binding to TNF-α mRNA. Additionally, we found dysregulated mannose metabolism in the colonic mucosa of patients with inflammatory bowel disease. Finally, we revealed that activating PMM2 activity with epalrestat, a clinically approved drug for the treatment of diabetic neuropathy, elicited further sensitization to the therapeutic effect of mannose. Therefore, mannose metabolism prevents TNF-α-mediated pathogenic crosstalk between IECs and intestinal macrophages, thereby normalizing aberrant immunometabolism in the gut.

Maternal exposure to different sizes of polystyrene microplastics during gestation causes metabolic disorders in their offspring.

Microplastics (MPs) are highly concerned environmental pollutants that are ubiquitous in the environmental and might affect human and animal health. In this study, we exposed pregnant mice to 0.5 and 5 µm with 100 and 1000 µg/L polystyrene MPs, then investigated maternal MPs exposure during gestation and evaluated the potential effects on the mice offspring (PND42). In the F1 offspring, the serum triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels and hepatic TC, TG levels were altered, while some of them were only significant in 5 µm MPs-treated group. Various serum metabolites including amino acids and acyl-carnitines were carried out by nonderivatized tandem mass spectrometry, there were 11 and 15 kinds of metabolites changes significantly in 0.5 and 5 µm MPs-treated groups, respectively. Furthermore, the changes of C0 and C0/(C16 + 18) indicators suggested the potential risk of fatty acid metabolism disorder, which was verified by hepatic genes expression. These results indicated that maternal exposure of two different sizes of polystyrene MPs increased risks of metabolic disorder in their offspring, and greater effects were observed in 5 µm MPs-treated groups. The data provides a preliminary exploration of the potential relationship between MPs and the risk metabolic disorder even in the next generation, which might offer new insights into the health risk assessment of MPs.

Chlorpyrifos exposure induces lipid metabolism disorder at the physiological and transcriptomic levels in larval zebrafish.

Chlorpyrifos (CPF) is a widely used insecticide in pest control, and it can affect aquatic animals by contaminating the water. In this study, larval zebrafish were exposed to CPF at concentrations of 30, 100 and 300 µg/l for 7 days. In the CPF-treated group, lipid droplet accumulation was reduced in larval zebrafish. The levels of triglyceride (TG), total cholesterol (TC), and pyruvate were also decreased after CPF exposure. Cellular apoptosis were significantly increased in the heart tissue after CPF exposure compared with the control. Transcription changes in cardiovascular genes were also observed. Through transcriptome analysis, we found that the transcription of 465 genes changed significantly, with 398 upregulated and 67 downregulated in the CPF-treated group, indicating that CPF exposure altered the transcription of genes. Among these altered genes, a number of genes were closely related to the glucose and lipid metabolism pathways. Furthermore, we also confirmed that the transcription of genes related to fatty acid synthesis, TC synthesis, and lipogenesis were significantly decreased in larval zebrafish after exposure to CPF. These results indicated that CPF exposure induced lipid metabolism disorders associated with cardiovascular toxicity in larval zebrafish.

Chronic exposure to low doses of Pb induces hepatotoxicity at the physiological, biochemical, and transcriptomic levels of mice.

Lead (Pb), a non-essential heavy metal, is a major global environmental contaminant with serious toxicological consequences. In the present study, the effects on hepatotoxicity of mice with chronic exposure to low doses of Pb were evaluated. While oral exposure to 0.03 or 0.1 mg/L Pb for 15 weeks in male adult mice had no significant effect on body weights, Pb exposure resulted in liver histopathological effects and increase of hepatic activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). In addition, hepatic reactive oxygen species (ROS) and malondialdehyde (MDA) significantly accumulated after treatment. Conversely, glutathione (GSH) decreased significantly in both 0.03 and 0.1 mg/L Pb-treated groups. Moreover, the hepatic activities of superoxide dismutase 1 (SOD) and catalase (CAT) increased significantly following treatment with 0.1 mg/L Pb for 15 weeks, concomitant with increases in transcriptions of hepatic Sod, Cat, and Gpx. Furthermore, transcriptions of hepatic metallothionein (MT), zinc transporter 5 (Znt5) and copper transporter 1 (Ctr1), and subsequent protein levels were also increased in liver of mice when exposed to 0.1 mg/L Pb for 15 weeks. In addition, the transcriptome data showed that Pb has substantial influence on several pathways, including PPAR signaling pathways, AMPK signaling pathways, fatty acid metabolism, and drug metabolism. Our data suggested that chronic Pb exposure could induce hepatotoxicity at the physiological, biochemical, and transcriptomic levels in mice.

Propamocarb exposure decreases the secretion of neurotransmitters and causes behavioral impairments in mice.

Propamocarb (PM) is a type of fungicide, which is widely used in the greenhouse-based production of vegetables and fruits globally. It has been considered to have generally low toxicity. However, the teratogenicity or neurotoxicity for mammals remains unclear. In this study, we aimed to explore its effect on the secretion of neurotransmitters and behavioral impairments. Male adult mice were exposed to 10 and 40 mg/L PM for 2 weeks (acute exposure) or 3 and 10 mg/L PM for 10 weeks (chronic exposure). It was observed that acute or chronic exposure to PM changed the levels of serotonin (5-HT) and dopamine in the serum and colon and the transcription of TPH2 and DRD2 in the colons of mice. In addition, the locomotor test, the open field test, and the Morris water maze analysis also showed that acute exposure to PM caused behavioral impairments to some extent. The results obtained in the present study indicated that PM has the potential to induce neurotoxicity in animals.

Chlorpyrifos disturbs hepatic metabolism associated with oxidative stress and gut microbiota dysbiosis in adult zebrafish.

Chlorpyrifos (CPF) is widely used in agriculture and is considered one of the most toxic pesticides to fish. In this study, adult male zebrafish were exposed to CPF at concentrations of 30, 100 and 300 µg/L for 21 days. It was observed that CPF not only induced oxidative stress but also caused gut microbiota dysbiosis in the gut. The malondialdehyde (MDA) levels increased, and the glutathione (GSH) contents decreased in the gut of the CPF-treated group. For the gut microbiota, at the phylum level, the relative abundance of Proteobacteria showed a significant change after CPF exposure. At the genus level, approximately 25 types of bacteria in the gut changed significantly. In addition, based on a gas chromatography combined with mass spectrometry (GC/MS) analysis, we found that 98 metabolites significantly influenced the zebrafish liver, and these changed metabolites were tightly related to several pathways, including glucose and lipid metabolism, the tricarboxylic acid (TCA) cycle, and amino acid metabolism. Furthermore, the transcriptional levels of some genes related to glycolysis and lipid metabolism decreased significantly in the livers of CPF-treated zebrafish. These results indicated that CPF exposure could induce hepatic glucose and lipid metabolism disorders in adult zebrafish. Taken together, our results suggest that CPF exposure causes hepatic lipid metabolism disorders that are associated with gut oxidative stress and microbiota dysbiosis in adult zebrafish.

Effects of polystyrene microplastics on the composition of the microbiome and metabolism in larval zebrafish.

Microplastics are major pollutants in marine environment and may have health effects on aquatic organisms. In this study, we used two sizes (5 and 50 µm diameter) of fluorescent and virgin polystyrene microplastics to analyze the adverse effects on larval zebrafish. In our study, we evaluated the effects on larval zebrafish after exposure to 100 and 1000 µg/L of two sizes of polystyrene microplastics for 7 days. Our results show that polystyrene microplastics could cause alterations in the microbiome at the phylum and genus levels in larval zebrafish, including changes in abundance and diversity of the microbiome. In addition, metabolomic analysis suggested that exposure to polystyrene microplastics induced alterations of metabolic profiles in larval zebrafish, and differential metabolites were involved in energy metabolism, glycolipid metabolism, inflammatory response, neurotoxic response, nucleic acid metabolism, oxidative stress. Polystyrene microplastics also significantly decreased the activities of catalase and the content of glutathione. In addition, the results of gene transcription analysis showed that exposure to polystyrene microplastics induced changes in glycolysis-related genes and lipid metabolism-related genes, confirming that polystyrene microplastics disturbed glycolipid and energy metabolism. Taken together, the results obtained in the present study indicated that the potential effects of environmental microplastics on aquatic organisms should not be ignored.

Short-term propamocarb exposure induces hepatic metabolism disorder associated with gut microbiota dysbiosis in adult male zebrafish.

Propamocarb (PM) is a pesticide that is widely used to protect cucumbers and other plants from downy mildew. Recently, some studies indicated that PM exposure had potential toxic effects in animals. In this study, adult male zebrafish were exposed to 100 and 1000 µg/l PM for 7 days to assess its effects on metabolism and the gut microbiota. We observed a significant decrease in triglyceride (TG) in the livers of zebrafish that were exposed to 1000 µg/l PM for 7 days. At the same time, some genes related to glycolysis and lipid metabolism in the livers of zebrafish, including hexokinase-1 (HK1), pyruvate kinase (PK), acyl-CoA oxidase (Aco), peroxisome proliferator activated receptor alpha (Ppar-α), apolipoprotein A-IV-like (Apo), Acetyl CoA carboxylase-1 (Acc1), diacylglycerol acyltransferase (Dgat), and fatty acid synthase (Fas), were also decreased significantly after PM exposure. Based on GC-MS metabolomics analysis, a total of 48 metabolites changed significantly in the 1000 µg/l PM treatment group in comparison with the control group. These altered metabolites were mainly associated with the glycolysis, amino acid metabolism, and lipid metabolism pathways. Interestingly, we further found that the 1000 µg/l PM treatment group also showed significant elevations in Proteobacteria, Bacteroidetes, and Firmicutes at the phylum level. Sequencing of the 16S rRNA gene in the V3-V4 region also showed a significant change in the abundance and diversity of the gut microbiota in the 1000 µg/l PM treatment group. Our results indicated that exposure to PM for a short time could induce hepatic metabolic disorders and gut microbiota dysbiosis in adult male zebrafish.