Effects of phosphodiesterase-4 inhibitor on the mucin secretion in airway stimulated with acrolein: experiment with rats

Abstract

To examine the effects of YM976, a phosphodiesterase (PDE)4 inhibitor, on mucin hypersecretion of airway stimulated with acrolein. Forty-eight SD rat were randomly divided into 6 equal groups. Twenty-four rats underwent gastric perfusion of YM976 0.5, 1.5, or 4.5 mgxkg(-1)xd(-1) (n=8 for each group) and then underwent aerosol inhalation of 3.0 ppm acrolein 6 hours per day for 12 days so as to establish rat models of airway mucus hypersecretion. Eight rats underwent aerosol inhalation of 3.0 ppm acrolein only for 12 days to establish rat models of airway mucus hypersecretion without any drug intervention (acrolein model group). Eight rats underwent gastric perfusion of 5% methylcellulose and then acrolein inhalation for 12 days (methylcellulose group), and another 8 rats underwent gastric perfusion of YM976 4.5 mg/kg once a day and then inhalation of normal saline for 12 days (YM976 control group). On the 13th day the rats were killed. Bronchoalveolar lavage fluid (BALF) was acquired for cell count, and ELISA was used to detect the levels of tumor necrosis factor (TNF)-alpha and cytokine-induced neutrophil chemoattractant (CINC)-1 in the BALF. The mucin level in the airway mucous membrane was detected by alcian blue(AB)/periodic acid-Schiff(PAS) method. Muc5ac protein was measured by immunohistochemical staining and Western-blotting, and Muc5ac mRNA was detected by RT-PCR. The percentages of positive AB/PAS staining of the acrolein model group and the 3 YM976 groups (0.5, 1.5, and 4.5 mgxkg(-1)xd(-1)) were 23.65+/-2.86, 22.63+/-2.12, 16.34+/-1.72, and 5.03+/-0.72 respectively. The integral optical density (IOD) levels of Muc5ac immunohistochemical staining of the methylcellulose group and the 3 YM976 groups were 0.54+/-0.05, 0.49+/-0.06, 0.32+/-0.04, and 0.22+/-0.04 respectively. The IOD of Muc5ac protein expression by Western-blotting of the methylcellulose group and the 3 YM976 groups were 1.177+/-0.190, 0.806+/-0.180, 0.303+/-0.061, and 0.134+/-0.035 respectively. The IOD of Muc5ac mRNA expression by RT-PCR of the methylcellulose group and the 3 YM976 groups were 0.246+/-0.021, 0.223+/-0.020, 0.161+/-0.012, and 0.097+/-0.011 respectively. The TNF-alpha and CINC-1 levels in the BALF of the methylcellulose group and the 3 YM976 groups were (96.77+/-2.31), (87.65+/-2.75), (73.56+/-2.62), and (52.23+/-2.79) microg/L respectively, and (145.75+/-4.43), (139.73+/-5.51), (95.34+/-5.13), and (65.74+/-5.62) microg/L respectively, all significantly higher than those of the normal control group [4.38+/-0.32, 0.12+/-0.02, 0.058+/-0.024, 0.061+/-0.006, (18.23+/-2.32) microg/L and (33.56+/-3.43) microg/L respectively, all P<0.05], but those of the YM976 1.5 mgxkg(-1)xd(-1) and 4.5 mgxkg(-1)xd(-1) groups being significantly lower than those of the methylcellulose group (both P<0.05). YM976 inhibits airway inflammatory response and airway mucin hypersecretion induced by acrolein.