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Objective To investigate the effect of Dectin-1 on the release of inflammatory factors interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α) in rat tracheal epithelial cells (RTECs) stimulated with heat-treated Candida glabrata (C.glabrata).Methods RTECs cultivated in vitro were randomly divided into three groups,including control group(RTECs + sterile normal saline),fungal stimulation group(RTECs + heat-treated C.glabrata),and inhibitor intervention group(RTECs + laminarin + heat-treated C.glabrata),cells were harvested after incubation for 0,2,4,6 hours respectively,cell survival rate was determined by MTT method,expression of Dectin-1 was analyzed by Western Blot,expression of IL-10 and TNF-α were detected by enzyme-linked immunosorbent assay (ELISA).Results Heat-treated C.glabrata destroyed cell structure and reduced cell survival rate.At the beginning of the culture (0 h),cell survival rate,expressions of Dectin-1,IL-10 and TNF-α among three groups were all not significantly different(all P＞0.05).After incubation for 2,4,6 hours,expressions of Dectin-1,IL-10 and TNF-α in fungal stimulation group and inhibitor intervention group were both significantly higher than control group;expressions of Dectin-1,IL-10,and TNF-α in inhibitor intervention group was lower than fungal stimulation group(all P＜0.05).The expressions of IL-10 in inhibitor intervention group at 0 h and 2 h was not significantly different,expressions of Dectin-1,IL-10,and TNF-α in fungal stimulation group and inhibitor intervention group at different incubation periods were significantly different(all P＜0.05).Conclusion Dectin-1 is an important receptor for RTECs to recognize the heat-treated C.glabrata,it induces the release of IL-10 and TNF-α,and mediate the occurrence of inflammation.
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BACKGROUND: Hypersecretion of mucin due to goblet cell hyperplasia is frequently encountered in many chronic airway diseases, such as chronic bronchitis, bronchiectasis, bronchial asthma and cystic fibrosis. Even in normal individuals, viral infection or bacterial pneumonia frequently provoke huge amounts of bronchial secretions which may cause airway obstruction. The production of mucin was regulated by epidermal growth factor (EGF) in vitro. To know whether this EGF system regulates mucin secretion in vivo and Pseudomonas also stimulates the mucin secretion by the same pathway, we studied these relationships in the cultured rat tracheal epithelial cells. METHODS: Rat tracheal epithelial cells were obtained by pronase dissociation from the male Fisher 344 rats. When cells became confluent, they were divided into 6 groups and stimulated with either EGF for 24 hours or Pseudomonas extracts for 12 hours with or without selective EGF-R tyrosine kinase inhibitor tyrphostin AG1478. RESULTS: We found that both EGF and Pseudomonas extracts phosphorylated the tyrosine residue in the EGF receptor from the rat tracheal epithelial cells and this tyrosine phosphorylation was nearly completely blocked by selective EGF-R tyrosine kinase inhibitor tyrphostin AG1478. The mucin secretion was also stimulated by either EGF or Pseudomonas extracts but more strong secretion of mucin and MUC5AC gene expression in the rat tracheal epithelial cell was done by Pseudomonas extracts. CONCLUSION: These data suggest that Pseudomonas secretes the mucin by way of the EGF receptor and MUC5AC gene expression and the inhibitors of EGF receptor tyrosine phosphorylation would be useful to prevent the huge production of mucin due to Pseudomonas aeruginosa lung infection.