Expression of airway mucus-associated proteins in rats with chronic obstructive pulmonary disease with a cold-dryness...

To reveal the effects on expression of airway mucus-associated proteins in rats with chronic obstructive pulmonary disease (COPD) and a cold-dryness symptom pattern induced by elastase and smoking.

The COPD model was established with an elastase dose into the trachea combined with exposure to smoking; the COPD model cold-dryness symptom pattern was further developed by exposure to a cold, dry environment. After 90 days, pathologic lung sections, inflammatory cytokine levels (measured by enzyme linked immunosorbent assay), mRNA and protein expression of mucus-associated proteins and aquaporins (measured by real-time polymerase chain reaction and western blots) were examined.

Cytokines interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) in the COPD and the cold-dryness symptom pattern COPD groups were all significantly higher than in controls (each P < 0.01). IL-6 and IL-8 levels were higher in the cold-dryness symptom pattern COPD group than in the COPD group (each P < 0.05). The AQP5 mRNA expression in the cold-dryness symptom pattern COPD and COPD groups was lower than in the control group (P < 0.01), and that in the cold-dryness symptom pattern COPD group was lower than the COPD group (P < 0.05). The expression of MUC5AC and MUC5B mRNAs in the cold-dryness symptom pattern COPD group and COPD group was higher than in the control group (each P < 0.01), and that in the cold-dryness symptom pattern COPD group was higher than the COPD group (P < 0.01, and P < 0.05, respectively). The ratio of MUC5AC mRNA/MUC5B mRNA was COPD group < the cold-dryness symptom pattern COPD group < the control group. AQP4 and AQP5 protein expression in the cold-dryness symptom pattern COPD group was lower than that in the COPD group which was lower again than in the control group. MUC5AC and MUC5B expression in the cold-dryness symptom pattern COPD group was higher than in the COPD group and higher again than in the control group.

Cold-dryness affects the expression of mucus-associated protein mRNA and its corresponding proteins, reducing the secretion of aquaporins and increasing the secretion of mucins. Imbalance in aquaporins and mucins can affect the function of mucus, increasing airway obstruction.