Insights into the effects of chronic combined chromium-nickel exposure on colon damage in mice through transcriptomic analysis and in vitro gastrointestinal digestion assay.

Heavy metals interact with each other in a coexisting manner to produce complex combined toxicity to organisms. At present, the toxic effects of chronic co-exposure to heavy metals hexavalent chromium [Cr(VI)] and divalent nickel [Ni(II)] on organisms are seldom studied and the related mechanisms are poorly understood. In this study, we explored the mechanism of the colon injury in mice caused by chronic exposure to Cr or/and Ni. The results showed that, compared with the control group, Cr or/and Ni chronic exposure affected the body weight of mice, and led to infiltration of inflammatory cells in the colon, decreased the number of goblet cells, fusion of intracellular mucus particles and damaged cell structure of intestinal epithelial. In the Cr or/and Ni exposure group, the activity of nitric oxide synthase (iNOS) increased, the expression levels of MUC2 were significantly down-regulated, and those of ZO-1 and Occludin were significantly up-regulated. Interestingly, factorial analysis revealed an interaction between Cr and Ni, which was manifested as antagonistic effects on iNOS activity, ZO-1 and MUC2 mRNA expression levels. Transcriptome sequencing further revealed that the expression of genes-related to inflammation, intestinal mucus and tight junctions changed obviously. Moreover, the relative contents of Cr(VI) and Ni(II) in the Cr, Ni and Cr+Ni groups all changed with in-vitro gastrointestinal （IVG）digestion, especially in the Cr+Ni group. Our results indicated that the chronic exposure to Cr or/and Ni can lead to damage to the mice colon, and the relative content changes of Cr(VI) and Ni(II) might be the main reason for the antagonistic effect of Cr+Ni exposure on the colon damage.

The macrophage polarization in allergic responses induced by tropomyosin of Macrobrachium nipponense in cell and murine models.

Macrophages are one of the important immune cells, which play important roles in innate and adaptive immune. However, the roles of macrophages in food allergy are not thoroughly understood. To investigate the roles of macrophages during food allergy, we focused on the relationship between macrophage polarization and allergic responses induced by tropomyosin (TM) in the present study. Arg 1 and CD206 expressions in the TM group were significantly higher than those of the PBS group, while iNOS and TNF-α expressions were no obvious difference, moreover, the morphology of macrophages stimulated by TM was similar to that of M2 macrophages. These results indicated macrophages were mainly polarized toward M2 phenotypes in vitro. The antibodies, mMCP-1, histamine and cytokines, revealed that macrophages could participate in food allergy, and macrophage polarization was associated with changes in allergic-related factors. The cytokine levels of M2 phenotypes were significantly higher than those of M1 phenotypes in peripheral blood. The mRNA expressions and protein levels of Arg1 and iNOS in the jejunum and peritoneal cells indicated that M2 phenotypes were the major macrophage in these tissues compared with M1 phenotypes. Hence, macrophage polarization plays an important role in food allergy.

Effects of chronic Cr and Ni co-exposure on liver inflammation and autophagy in mice by regulating the TLR4/mTOR pathway.

Exposure to Cr and/or Ni can have widespread implications on the environment and health. However, the specific toxic effects of chronic Cr and Ni co-exposure on mice liver have not been reported. To ascertain the combined toxic effects of chronic Cr and Ni co-exposure on liver damage in mice, 80 6-week-old female C57BL/6 J mice were randomly divided into 4 groups: the Con group, Cr group (Cr+6 50 mg/L), Ni group (Ni+2 110 mg/L), and Cr + Ni group (Cr+6 50 mg/L + Ni+2 110 mg/L). The trial period lasted for 16 weeks. The results showed that Cr+6 and/or Ni+2 increased liver weight and liver index (P < 0.05) in mice, caused histological abnormality and ultrastructural damage, and micronutrients imbalance in mice liver. These findings serve as the basis for subsequent experiments. Compared with the individual exposure group, chronic Cr and Ni co-exposure resulted in decreased levels and activities of ALT, AST, MDA, T-AOC, and T-SOD (P < 0.05) in liver tissue, and decreased the mRNA expression levels of the TLR4/mTOR pathway related factors (TLR4, TRAM, TRIF, TBK-1, IRF-3, MyD88, IRAK-4, TRAF6, TAK-1, IKKß, NF-κB, IL-1ß, IL-6, TNFα, ULK1, Beclin 1, LC3) (P < 0.05) and decreased the protein expression levels of the factors (TLR4, MyD88, TRAF6, NF-κB p50, IL-6, TNFα, ULK1, LC3II/LC3I) (P < 0.05). Moreover, factorial analysis revealed the interaction between Cr and Ni, which was manifested as antagonistic effects on Cr concentration, Ni concentration, and TLR4, MyD88, NF-κB, mTOR, LC3, and p62 mRNA expression levels. In conclusion, the TLR4/mTOR pathway as a mechanism through which chronic Cr and Ni co-exposure induce liver inflammation and autophagy in mice, and there was an antagonistic effect between Cr and Ni. The above results provided a theoretical basis for understanding the underlying processes.

Microbial colony sequencing combined with metabolomics revealed the effects of chronic hexavalent chromium and nickel combined exposure on intestinal inflammation in mice.

The pollution and toxic effects of hexavalent chromium [Cr(VI)] and divalent nickel [Ni(II)] have become worldwide public health issues. However, the potential detailed effects of chronic combined Cr(VI) and Ni exposure on colonic inflammation in mice have not been reported. In this study, 16S rDNA sequencing, metabolomics data analysis, qPCR and other related experimental techniques were used to comprehensively explore the mechanism of toxic damage and the inflammatory response of the colon in mice under the co-toxicity of chronic hexavalent chromium and nickel. The results showed that long-term exposure to Cr(VI) and/or Ni resulted in an imbalance of trace elements in the colon of mice with significant inflammatory infiltration of tissues. Moreover, Cr(VI) and/or Ni poisoning upregulated the expression levels of IL-6, IL-18, IL-1ß, TNF-α, IFN-γ, JAK2 and STAT3 mRNA, and downregulated IL-10 mRNA, which was highly consistent with the trend in protein expression. Combined with multiomics analysis, Cr(VI) and/or Ni could change the α diversity and ß diversity of the gut microbiota and induce significant differential changes in metabolites such as Pyroglu-Glu-Lys, Val-Asp-Arg, stearidonic acid, and 20-hydroxyarachidonic acid. They are also associated with disorders of important metabolic pathways such as lipid metabolism and amino acid metabolism. Correlation analysis revealed that there was a significant correlation between gut microbes and metabolites (P < 0.05). In summary, based on the advantages of comprehensive analysis of high-throughput sequencing sets, these results suggest that chronic exposure to Cr(VI) and Ni in combination can cause microbial flora imbalances, induce metabolic disorders, and subsequently cause colonic damage in mice. These data provide new insights into the toxicology and molecular mechanisms of Cr(VI) and Ni.

Phosphatidylethanolamine-binding protein 4 deficiency exacerbates carbon tetrachloride-induced liver fibrosis by regulating the NF-κB signaling pathway.

Liver fibrosis is a pathological process which can progress to hepatocirrhosis, even hepatocellular carcinoma. Phosphatidylethanolamine-binding protein 4 (PEBP4) is a secreted protein involved in regulating many molecular pathways, whereas its roles in diseases including hepatic fibrosis remain undefined. The nuclear factor-κappa B (NF-κB) signaling pathway has been found to be involved in the development of liver fibrosis. In this study, we generated a hepatocyte-conditional knockout (CKO) mouse model of PEBP4, and explored the potential functions of PEBP4 on liver fibrosis and the NF-κB signaling pathway in a mouse model of carbon tetrachloride (CCl4)-induced liver fibrosis. We demonstrated that PEBP4 CKO aggravated CCl4-triggered liver fibrosis, as evidenced by altered histopathology, an increase in the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and hydroxyproline (HYP) levels, and more collagen deposition, as well as by enhanced expression of fibrotic markers including α-smooth muscle actin (α-SMA), collagen I and collagen III. Mechanistically, PEBP4 deficiency activated the NF-κB signaling pathway, as indicated by increased phosphorylation of NF-κB p65 and inhibitor protein κB inhibitor-α (IκB-α), and nuclear NF-κB p65 expression in the fibrotic liver. Notably, the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) partially blocked the activation of the NF-κB pathway, and reversed the pro-fibrotic effect of PEBP4 deletion in CCl4-treated mice. Together, these results suggest that PEBP4 deficiency results in aggravation of liver fibrosis and activation of the NF-κB signaling pathway, supporting a novel concept that PEBP4 is a crucial player in hepatic fibrosis, but also might be a negative regulator of the NF-κB signaling in liver fibrosis.

Hepatocyte-Conditional Knockout of Phosphatidylethanolamine Binding Protein 4 Aggravated LPS/D-GalN-Induced Acute Liver Injury via the TLR4/NF-κB Pathway.

Acute liver injury (ALI) is a disease that seriously threatens human health and life, and a dysregulated inflammation response is one of the main mechanisms of ALI induced by various factors. Phosphatidylethanolamine binding protein 4 (PEBP4) is a secreted protein with multiple biological functions. At present, studies on PEBP4 exist mainly in the field of tumors and rarely in inflammation. This study aimed to explore the potential roles and mechanisms of PEBP4 on lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced ALI. PEBP4 was downregulated after treatment with LPS/D-GalN in wild-type mice. PEBP4 hepatocyte-conditional knockout (CKO) aggravated liver damage and repressed liver functions, including hepatocellular edema, red blood cell infiltration, and increased aspartate aminotransferase (AST)/alanine aminotrans-ferase (ALT) activities. The inflammatory response was promoted through increased neutrophil infiltration, myeloperoxidase (MPO) activities, and cytokine secretions (interleukin-1ß, IL-1ß; tumor necrosis factor alpha, TNF-α; and cyclooxygenase-2, COX-2) in PEBP4 CKO mice. PEBP4 CKO also induced an apoptotic effect, including increasing the degree of apoptotic hepatocytes, the expressions and activities of caspases, and pro-apoptotic factor Bax while decreasing anti-apoptotic factor Bcl-2. Furthermore, the data demonstrated the levels of Toll-like receptor 4 (TLR4), phosphorylation-inhibitor of nuclear factor kappaB Alpha (p-IκB-α), and nuclear factor kappaB (NF-κB) p65 were upregulated, while the expressions of cytoplasmic IκB-α and NF-κB p65 were downregulated after PEBP4 CKO. More importantly, both the NF-κB inhibitor (Ammonium pyrrolidinedithiocarbamate, PDTC) and a small-molecule inhibitor of TLR4 (TAK-242) could inhibit TLR4/NF-κB signaling activation and reverse the effects of PEBP4 CKO. In summary, the data suggested that hepatocyte-conditional knockout of PEBP4 aggravated LPS/D-GalN-induced ALI, and the effect is partly mediated by activation of the TLR4/NF-κB signaling pathway.

Inhibitory effect and mechanism of exogenous mammalian sterile 20-like kinase 1 on the growth of human colorectal cancer.

The present study aimed to observe the inhibitory effect and preliminary mechanism of exogenous mammalian sterile 20-like kinase 1 (MST1) on the growth of colorectal cancer SW480 cells. The SW480 cells were randomly divided into the following groups: Control, empty enhanced green fluorescent protein (EGFP) plasmid (pEGFP-N1), MST1 EGFP plasmid (pEGFP-MST1), 20 µmol/l fluorouracil (5-FU) and pEGFP-MST1 + 5-FU. An MTS colorimetric assay was used to detect cell viability, Hoechst 33342 staining was used to observe cell apoptosis, and western blotting and immunohistochemistry were used to detect the levels of the proteins MST1, yes-associated protein (YAP), phospho-YAP1 (Ser127), p53 and p53 upregulated modulator of apoptosis (PUMA). In addition, nude mice were injected with SW480 cells to assess the tumor inhibition rates. Compared with the control group, the growth inhibition and apoptosis rates, the levels of MST1, p53 and PUMA, and the ratios of phospho-YAP1/YAP in the pEGFP-MST1 and pEGFP-MST1 + 5-FU groups were increased significantly (P<0.01). Additionally, relative to the control group, the tumor inhibition rates in the nude mice transplanted with SW480 cells of the pEGFP-MST1 and pEGFP-MST1 + 5-FU groups were 48.52±1.63 and 87.28±2.58%, respectively, and the positive rates of phospho-YAP1 (Ser127) protein in nuclei increased significantly (P<0.01). Overall, exogenous MST1 effectively inhibited the proliferation and growth of transplanted human colorectal cancer cells and promoted cancer cell apoptosis. The mechanism involved may be associated with the increase of intracellular phospho-YAP1 (Ser127) protein.

Taurine induces the apoptosis of breast cancer cells by regulating apoptosis-related proteins of mitochondria.

Taurine (Tau), the most abundant free amino acid in humans has numerous potential health benefits through its antioxidant and anti-inflammatory properties. However, limited studies have assessed its effect on tumors and the antitumor mechanism remains unknown. The present study investigated the cellular and molecular changes induced by Tau, leading to the induction of apoptosis in human breast cancer cell lines MCF-7 and MDA-MB-231. MCF-7 is p53 proficient (p53+/+) and MDA-MB-231 is a p53 null mutant (p53-/-). Cell proliferation and viability were assessed by MTT. Flow cytometry and hoechst33342 fluorescent staining were employed to detect apoptosis. Spectrophotometry was used to detect caspase-3 activity. Reverse transcription-polymerase chain reaction and western blot analysis were used to detect the levels of mRNA and proteins of p53-upregulated modulator of apoptosis (PUMA), Bax and Bcl-2. Finally, the affect of Tau on the growth of MDA-MB-231-cell-nude mice xenografts was examined. In the study, Tau inhibited growth and induced apoptosis of the two cell lines in a concentration- and time-dependent manner. Notably, the inhibitory effect of Tau on p53-/- cancer cells was clearly significant compared to the p53+/+ cancer cells. Further studies showed that Tau promoted apoptosis in human breast cancer cells and inhibited the growth of tumor in nude mice by inducing the expression of PUMA, which further up- and downregulated the expression of Bax and Bcl-2 protein, giving rise to increased activation of caspase-3. Collectively, these results indicate that Tau is a potent candidate for the chemotherapy of breast cancer through increasing the PUMA expression independent of p53 status.