Clostridium difficile toxin B-induced colonic inflammation is mediated by the FOXO3/PPM1B pathway in fetal human colon epithelial cells.

Clostridium difficile (C. difficile) toxin B (TcdB) is as an inflammatory enterotoxin that accounts for manifestations of widespread healthcare-associated C. difficile infection, including colonic inflammation. The present work explored the molecular mechanism by which TcdB activates innate immunity and stimulates pro-inflammatory cytokine release. Fetal human colon epithelial cells (FHCs) were treated with recombinant TcdB protein. Cell growth inhibition and apoptosis were measured with Cell Counting Kit-8 and Annexin V-fluorescein isothiocyanate Apoptosis Detection Kit, respectively. Flow cytometry analysis was also performed. Inflammatory cytokine induction was determined with enzykeme-linked immunosorbent assay analyses. Protein expression was assessed by western blot analysis. Gene overexpression and knockdown were performed with lentiviral transduction. Real-time quantitative polymerase chain reaction was used to examine gene expression. Dual-luciferase reporter assays and chromatin immunoprecipitation were implemented to explore transcriptional regulation. Mouse colon tissues were analyzed with hematoxylin and eosin staining. The results show that TcdB-induced cell growth and apoptosis and enhanced expression of interleukin-6 and tumor necrosis factor alpha in FHCs. We identified protein phosphatase magnesium-dependent 1B (PPM1B) as the key mediator promoting the phosphorylation of nuclear factor-κB p65, which accounted for the increase in pro-inflammatory cytokines. The findings demonstrate that PPM1B expression is directly regulated by the AKT/FOXO3 signaling pathway in FHCs. We confirmed the molecular mechanism with in vivo studies using a mouse model infected with C. difficile and treated with a phosphoinositide 3-kinase/AKT signaling inhibitor. In conclusion, TcdB induces inflammation in human colon epithelial cells by regulating the AKT/FOXO3/PPM1B pathway.

[Overexpression of miR-31 regulates TLR4/NF-κB signaling pathway and apoptotic protein in colitis model mice].

Objective: To investigate the effects of miR-31 on TLR4/NF-κB signaling pathway and apoptosis-related proteins in dextran sulfate sodium (DSS) induced mouse colon colitis. Methods: ① Mouse model of colon colitis: 1% DSS was used to induce mouse ulcerative colitis (UC). Fourteen FVB non-transgenic mice were randomly divided into control group (n= 6), DSS group (n= 8), and 16 FVB miR-31 transgenic mice were randomly divided into miR-31 overexpression group (n= 8), miR-31 overexpression +DSS group (n= 8). DSS was dissolved in water and administered to mice by drinking water. The DSS group and miR-31+DSS group drank 1% DSS water in the first week, normal sterilized water in the second week, and 1% DSS water in the third week, after 5 weeks, the modeling was completed, then the colon tissues of the mice were collected. Western blot and IHC were used to detect the expressions of NF-κB p65, TLR4, Bax and Bcl-2 proteins in mouse colon tissue, TUNEL was used to detect apoptosis of mouse colon tissues. ② Cell culture experiments: Transfection of miR-31mimic and inhibitor by lipofectamine resulted in overexpression or knockdown of miR-31 in human colon epithelial cell line HCT 116 cells, each group was repeated three times and cells were collected 48 h later, Western blot was used to detect the expressions of NF-κB p65 and TLR4 protein. Results: ① In animal experiments, compared with the control group, the expression levels of NF-κB p65, TLR4 protein and apoptotic cell index in the DSS group and miR-31 overexpression group in mouse colon tissue were significantly increased (P＜0.05 or P＜0.01), and the Bcl-2 / Bax ratio was significantly reduced (P＜0.05 or P＜0.01); and compared with the DSS group, the expression levels of NF-κB p65, TLR4 protein and apoptotic cell index in the miR-31+DSS group were significantly increased (P＜0.01), while the Bcl-2/Bax ratio was significantly decreased (P＜0.01). ② In cell experiments, compared with the control group, the expression levels of NF-κB p65 and TLR4 protein in the over-expressed miR-31 group of HCT 116 cells were significantly increased (P＜0.05 or P＜0.01), the expressions of NF-κB p65 and TLR4 protein in miR-31 knockdown group were decreased (P＜0.05). Conclusion: miR-31 promotes the development of colitis by promoting TLR4/NF-κB signaling pathway and mediating apoptosis of intestinal epithelial cells.

Overexpression of miR-31 regulates TLR4/NF-κB signaling pathway and apoptotic protein in colitis model mice / 中国应用生理学杂志

To investigate the effects of miR-31 on TLR4/NF-κB signaling pathway and apoptosis-related proteins in dextran sulfate sodium (DSS) induced mouse colon colitis. Methods: ① Mouse model of colon colitis: 1% DSS was used to induce mouse ulcerative colitis (UC). Fourteen FVB non-transgenic mice were randomly divided into control group (n= 6), DSS group (n= 8), and 16 FVB miR-31 transgenic mice were randomly divided into miR-31 overexpression group (n= 8), miR-31 overexpression +DSS group (n= 8). DSS was dissolved in water and administered to mice by drinking water. The DSS group and miR-31+DSS group drank 1% DSS water in the first week, normal sterilized water in the second week, and 1% DSS water in the third week, after 5 weeks, the modeling was completed, then the colon tissues of the mice were collected. Western blot and IHC were used to detect the expressions of NF-κB p65, TLR4, Bax and Bcl-2 proteins in mouse colon tissue, TUNEL was used to detect apoptosis of mouse colon tissues. ② Cell culture experiments: Transfection of miR-31mimic and inhibitor by lipofectamine resulted in overexpression or knockdown of miR-31 in human colon epithelial cell line HCT 116 cells, each group was repeated three times and cells were collected 48 h later, Western blot was used to detect the expressions of NF-κB p65 and TLR4 protein. ① In animal experiments, compared with the control group, the expression levels of NF-κB p65, TLR4 protein and apoptotic cell index in the DSS group and miR-31 overexpression group in mouse colon tissue were significantly increased (P＜0.05 or P＜0.01), and the Bcl-2 / Bax ratio was significantly reduced (P＜0.05 or P＜0.01); and compared with the DSS group, the expression levels of NF-κB p65, TLR4 protein and apoptotic cell index in the miR-31+DSS group were significantly increased (P＜0.01), while the Bcl-2/Bax ratio was significantly decreased (P＜0.01). ② In cell experiments, compared with the control group, the expression levels of NF-κB p65 and TLR4 protein in the over-expressed miR-31 group of HCT 116 cells were significantly increased (P＜0.05 or P＜0.01), the expressions of NF-κB p65 and TLR4 protein in miR-31 knockdown group were decreased (P＜0.05). miR-31 promotes the development of colitis by promoting TLR4/NF-κB signaling pathway and mediating apoptosis of intestinal epithelial cells.

Effect of magnesium-calcium alloy extract on matrix metalloproteinase-9 and matrix metalloproteinase inhibitor-3 in human colonic epithelial cells / 新乡医学院学报

Objective To investigate the effect of different concentrations of magnesium-calcium alloy extract on the expression of matrix metalloproteinase-9 (MMP9) and tissue inhibitor of metalloproteinase-3 (TIMP3) in human colonic epithelial NCM460 cells.Methods The different concentrations of extracts (the volume fraction was 10％,50％ and 100％ respectively) were made with magnesium-calcium alloy.The 5 × 106 L-1 NCM460 suspension was randomly divided into control group,experimental group 1,experimental group 2 and experimental group 3.The cells in the control group were cultured by 2 000 μL high glucose Dulbecco's modified Eagle's medium (containing 10％ volume fraction of fetal bovine serum).The cells in the experimental group 1,2 and 3 were cultured by 2 000 μL magnesium-calcium alloy extract with volume fraction of 10％,50％ and 100％ respectively.The expressions of MMP9 and TIMP3 mRNA in NCM460 cells was detected by real-time fluorescence quantitative polymerase chain reaction,and the expression of MMP9 and TIMP3 protein in NCM460 cells was detected by Western blot at after one,three and five days of cultivation respectively.Results The expression of MMP9 mRNA and TIMP3 mRNA in NCM460 cells of the experimental group 1,2 and 3 was significantly lower than that in the control group after one day of cultivation (P ＜ 0.05).After three and five days of cultivation,the expression of MMP9 mRNA in NCM460 cells of the experimental group 1 was significantly lower than that in the control group (P ＜ 0.05),but the expression of MMP9 mRNA in the NCM460 cells of the experimental group 2 and 3 was significantly higher than that in the control group and the experimental group 1 (P ＜ 0.05).The expression of MMP9 mRNA in NCM460 cells of the experimental group 3 was significantly higher than that in the experimental group 2 after five days of cultivation (P ＜ 0.05).The expression of MMP9 mRNA in NCM460 cells of the experimental group 1,2 and 3 after three and five days of cultivation was significantly higher than that after one day of cultivation(P ＜ 0.05).There was no significant difference in the expression of MMP9 mRNA in NCM460 cells of the experimental group 1 between three and five days of cultivation (P ＞ 0.05).The expression of MMP9 mRNA in NCM460 cells of the experimental group 2 and 3 after five days of cultivation was significantly higher than that after three days of cultivation(P ＜ 0.05).The expression of TIMP3 mRNA in NCM460 cells of the experimental group 2 and 3 was significantly higher than that in the experimental group 1 after one day of euhivation (P ＜ 0.05).After three days of cultivation,the expression of TIMP3 mRNA in NCM460 cells of the experimental group 1,2 and 3 was significantly lower than that in the control group (P ＜ 0.05);the expression of TIMP3 mRNA in NCM460 cells of the experimental group 2 was significantly lower than that in the experimental group 1 and 3 (P ＜ 0.05).After five days of cultivation,the expression of TIMP3 mRNA in NCM460 cells of the experimental group 1,2 and 3 was significantly higher than that in the control group (P ＜ 0.05).The expression of TIMP3 mRNA in NCM460 cells after three and five days of cultivation was significantly higher than that after one day of cultivation (P ＜ 0.05),and the expression of TIMP3 after five days of cultivation was significantly higher than that after three days of cultivation in the experimental group 1 (P ＜ 0.05).The expression of TIMP3 mRNA in NCM460 cells after three days of cultivation was significantly lower than that after one day of cultivation (P ＜ 0.05),and the expression of TIMP3 after five days of cultivation was significantly higher than that after one and three days of cultivation in the experimental group 2 (P ＜ 0.05).The expression of TIMP3 mRNA in NCM460 cells after five days of cultivation was significantly higher than that after one and three days of cultivation in the experimental group 3 (P ＜ 0.05).After five days of cultivation,there was no significant difference in the expression of MMP9 protein in NCM460 cells between the experimental group 1 and control group (P ＞ 0.05),the expression of MMP9 protein in NCM460 cells of the experimental group 2 and 3 was significantly higher than that in the control group and the experimental group 1 (P ＜ 0.05),but there was no significant difference in the expression of MMP9 protein in NCM460 cells between the experimental group 2 and 3 (P ＞ 0.05).After five days of cultivation,the expression of TIMP3 protein in NCM460 cells of the experimental group 1,2 and 3 was significantly higher than that in the control group (P ＜0.05);but there was no significant difference in the expression of TIMP3 protein in NCM460 cells among the experimental group 1,2and 3 (P ＞ 0.05).Conclusions The high concentration of magnesium-calcium alloy extract has certain influence on the expression of MMP9 and TIMP3 gene in NCM460 cells,which may lead to the early inflammatory reaction,and the mechanism may be related to the calcium ion concentration in the extract.