Blocking of thromboxane A2 receptor attenuates airway mucus hyperproduction induced by cigarette smoke.

Cigarette smoking is one of the risk factors for chronic obstructive pulmonary disease (COPD). In this study, we investigated the effects of thromboxane A2 (TxA2) receptor antagonists on airway mucus production induced by cigarette smoke. Rats were exposed to cigarette smoke 1h/day, 6 days/week for 4 weeks. Seratrodast (2, 5, 10mg/kg day) was administered intragastrically prior to smoke exposure. Thromboxane B2 (TxB2) in the bronchoalveolar lavage fluid and lung tissues was determined by enzyme immunoassay. Airway mucus production was determined by alcin-blue/periodic acid sthiff (AB-PAS) staining, Muc5ac immunohistochemical staining, and RT-PCR. The phosphorylation of ERK and p38 was evaluated by Western blotting. Seratrodast reduced the overproduction of TxB2 in both bronchoalveolar lavage fluid and lung tissues. Cigarette smoke exposure markedly increased AB/PAS-stained goblet cells and rat Muc5ac expression in the airway, which was significantly attenuated by seratrodast administration. The induced phosphorylation of ERK and p38 was also attenuated by seratrodast. TxA2 receptor antagonist could reduce Muc5ac production induced by cigarette smoke in vivo, possibly through the mitogen-activated protein kinases (MAPK) signaling pathway.

Blockade of advanced glycation end product formation attenuates bleomycin-induced pulmonary fibrosis in rats.

BACKGROUND: Advanced glycation end products (AGEs) have been proposed to be involved in pulmonary fibrosis, but its role in this process has not been fully understood. To investigate the role of AGE formation in pulmonary fibrosis, we used a bleomycin (BLM)-stimulated rat model treated with aminoguanidine (AG), a crosslink inhibitor of AGE formation. METHODS: Rats were intratracheally instilled with BLM (5 mg/kg) and orally administered with AG (40, 80, 120 mg/kg) once daily for two weeks. AGEs level in lung tissue was determined by ELISA and pulmonary fibrosis was evaluated by Ashcroft score and hydroxyproline assay. The expression of heat shock protein 47 (HSP47), a collagen specific molecular chaperone, was measured with RT-PCR and Western blot. Moreover, TGFbeta1 and its downstream Smad proteins were analyzed by Western blot. RESULTS: AGEs level in rat lungs, as well as lung hydroxyproline content and Ashcroft score, was significantly enhanced by BLM stimulation, which was abrogated by AG treatment. BLM significantly increased the expression of HSP47 mRNA and protein in lung tissues, and AG treatment markedly decreased BLM-induced HSP47 expression in a dose-dependent manner (p < 0.05). In addition, AG dose-dependently downregulated BLM-stimulated overexpressions of TGFbeta1, phosphorylated (p)-Smad2 and p-Smad3 protein in lung tissues. CONCLUSION: These findings suggest AGE formation may participate in the process of BLM-induced pulmonary fibrosis, and blockade of AGE formation by AG treatment attenuates BLM-induced pulmonary fibrosis in rats, which is implicated in inhibition of HSP47 expression and TGFbeta/Smads signaling.

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

OBJECTIVE: To examine the effects of YM976, a phosphodiesterase (PDE)4 inhibitor, on mucin hypersecretion of airway stimulated with acrolein. METHODS: 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. RESULTS: 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). CONCLUSION: YM976 inhibits airway inflammatory response and airway mucin hypersecretion induced by acrolein.