OBJECTIVETo study the effects of alltrans retinoic acid (ATRA) on airway responsiveness, airway remodeling and expression of matrix metalloproteinase-9 (MMP-9) protein in rats with asthma.

METHODSForty rats were randomly divided into five groups: asthma model, normal saline (control), ATRA treatment, cotton oil treatment and budesonide treatment (n=8 each). Asthma was induced by ovalbumin sensitization and challenge in the asthma model, and the ATRA, cotton oil or budesonide treatment groups. ATRA (50 μg/kg), cotton oil (1 mL) or budesonide (0.32 mg/kg) was administered before ovalbumin challenge in the three treatment groups. Airway responsiveness was assessed. The lung tissues were sampled to detect airway remodeling and the expression of MMP-9 protein by immunohistochemistry.

RESULTSThe expression of MMP-9 in lung tissues in the ATRA treatment group was significantly higher than that in the control group, but the airway responsiveness in the ATRA treatment group was not significantly different from that in the control group. The airway responsiveness and the expression of MMP-9 in lung tissues were significantly reduced in the ATRA treatment group compared with the asthma model group. The airway remodeling was significantly improved in the ATRA treatment group compared with the asthma model group.

CONCLUSIONSATRA may alleviate airway hyperresponsiveness and airway remodeling possibly through decreasing the protein expression of MMP-9 in rats with asthma.