Triptolide Inhibits Lipopolysaccharide-Induced MUC5AC/5B Expression via Nuclear Factor-Kappa B in Human Airway Epithelial Cells / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The representative mucin genes in the human airway are MUC5AC and MUC5B, which are regulated by several inflammatory and anti-inflammatory substances. Triptolide (TPL), udenafil, betulinic acid, changkil saponin, and glucosteroid are some of the many anti-inflammatory substances that exist. TPL is a diterpenoid compound from the thunder god vine, which is used in traditional Chinese medicine for treatment of immune inflammatory diseases, such as rheumatoid arthritis, systemic lupus erythematosus, nephritis and asthma. However, the effects of TPL on mucin expression of human airway epithelial cells have yet to be reported. Hence, this study investigated the effect of TPL on lipopolysaccharide (LPS)-induced MUC5AC and MUC5B expression in human airway epithelial cells. SUBJECTS AND METHOD: The NCI-H292 cells and the primary cultures of human nasal epithelial cells were used to investigate the effects of TPL on LPS-induced MUC5AC and MUC5B expression using real-time polymerase chain reaction, enzyme immunoassay, and Western blot. RESULTS: TPL significantly decreased the LPS-induced MUC5AC and MUC5B mRNA expression and protein production. TPL also significantly decreased the nuclear factor-kappa B (NF-kB) phosphorylation. CONCLUSION: These results suggest that TPL down regulates MUC5AC and MUC5B expression via inhibition of NF-kB activation in human airway epithelial cells. This study may provide important information about the biological role of triptolide on mucus-secretion in airway inflammatory diseases and the development of novel therapeutic agents for controlling such diseases.

Effect of Polyinosinic-Polycytidylic Acid on MUC5B Expression in Human Airway Epithelial Cells / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Polyinosinic-polycytidylic acid (Poly I:C) is structurally similar to double-stranded RNA, and is known to induce various inflammatory mediators and to cause inflammatory reactions in airway epithelial cells. However, the effect of Poly I:C on secretion of mucins in human airway epithelial cells has been very rarely reported. In this study, the effect and brief signaling pathway of Poly I:C on the expression of mucin genes were investigated in human airway epithelial cells. MATERIALS AND METHOD: In mucin-producing human NCI-H292 airway epithelial cells and the primary cultures of normal human nasal epithelial cells, the effect and signaling pathway of Poly I:C on expression of mucin genes were investigated using reverse transcriptase-polymerase chain reaction, real-time PCR, enzyme immunoassay, and immunoblot analysis with specific inhibitors and small interfering RNA (siRNA) for mitogen-activated protein kinase (MAPK). RESULTS: Poly I:C induced the MUC5B expression, and activated the phosphorylation of ERK1/2 and p38 MAPK. U0126 (ERK1/2 MAPK inhibitor) and SB203580 (p38 MAPK inhibitor) inhibited the Poly I:C-induced MUC5B expression. In addition, the knockdown of ERK2 and p38 MAPK by siRNA significantly blocked the Poly I:C-induced MUC5B mRNA expression. CONCLUSION: Poly I:C induces the MUC5B expression via ERK2 and p38 MAPK signaling pathways in human airway epithelial cells. Therefore, Poly I:C may play a role in the regulation of mucus hypersecretion through MAPK signaling pathways in the human airway epithelial cells.

Effect of Multi-Walled Carbon Nanotubes on MUC5AC and MUC5B Expression in Airway Epithelial Cells / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Multi-walled carbon nanotubes (MWCNT) are one of the most commonly used nanomaterials to date. Recent studies have demonstrated that MWCNT increase immune response and allergic inflammation in airway epithelial cells. However, the effects of MWCNT on mucin in human airway epithelial cells have not been reported. Therefore, in the present study, the effect of MWCNT on MUC16, MUC5AC, and MUC5B expressions were investigated in human airway epithelial cells. SUBJECTS AND METHOD: In mucin-producing human NCI-H292 airway epithelial cells and primary cultures of normal nasal epithelial cells, the effects of MWCNT on MUC16, MUC5AC, and MUC5B expression were analyzed by reverse transcription polymerase chain reaction, real-time polymerase chain reaction, and enzyme-linked immunosorbent assay. RESULTS: In human NCI-H292 airway epithelial cells, MWCNT significantly induced the expression MUC5AC and MUC5B mRNA and the production of MUC5AC and MUC5B protein. However, MWCNT did not induce the expression of MUC16 mRNA. In the primary cultures of normal nasal epithelial cells, MWCNT also induced the expression of MUC5AC and MUC5B mRNA and the production of MUC5AC and MUC5B proteins. CONCLUSION: The results of this study demonstrate that MWCNT induces MUC5AC and MUC5B expression in human airway epithelial cells. These findings provide important information about the biological role of MWCNT on mucus-secretion in human airway epithelial cells.

Effects of Phytoestrogens on Glucose Metabolism in C57BL/KsOlaHsd-db/db Mice

This study was conducted to evaluate the antihyperglycemic effects of three phytoestrogens, genistein, coumestrol, and enterolactone, in type 2 diabetic animals. Forty male C57BL/KsOlaHsd-db/db mice were used as a diabetic animal model. The animals were divided into four groups and fed a phytoestrogen-free AIN-76 diet (control), or one of three phytoestrogen-supplemented (3.75 mg/100 g diet) AIN-76 diets for six weeks. During the experimental period, fasting blood glucose levels were measured on week 0, 2, 5, and 6 of the experiment, and oral glucose tolerance tests were performed on the 5th week. After the experimental period, blood concentrations of HbA1c, insulin, and glucagon were measured, and hepatic glycogen content and glucose regulating enzyme activities were analyzed. Fasting blood glucose, HbA1c level, and the area under the blood glucose curve in the oral glucose tolerance test were significantly lower in all of the phytoestrogen-supplemented groups compared to the control group. Plasma glucagon levels were also significantly lower in all of the phytoestrogen-supplemented groups compared to the control group. Hepatic glycogen level was significantly higher in the coumestrol-supplemented group compared to the other groups. However, there were no significant differences in the activities of glucokinase and glucose-6-phosphatase between the groups. These results suggest that all of the three major phytoestrogens tested in the present study were effective in lowering blood glucose levels in type 2 diabetic animals. However, further studies need to be conducted to elucidate the exact mechanism for the hypoglycemic effects of phytoestrogens.