To explore the potential mechanism of morin in improving airway inflammation in asthma.

In animal experiments, rats were randomly divided into four groups, with 10 rats in each group: animal control group, animal model group [ovalbumins (OVA)-induced], animal experimental-L group (OVA-induced + 10 mg·kg^-1 morin), animal experimental-M (OVA-induced+30 mg·kg^-1 morin) and the experimental-H group (OVA-induced+100 mg·kg^-1 morin). After 4 weeks of treatment, bronchoalveolar lavage fluid (BALF) and serum were collected for subsequent use, and lung tissues were harvested. Western blot assay was used to detect the expression of murine double minute 2(MDM2) protein; enzyme-linked immunosorbent assay (ELISA) assay was employed to determine the expression of inflammatory factors in BALF; and real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) assay was applied to measure the mRNA expressions of tumor protein 53 (p53) and BCL-2 associated X protein (Bax). In cell experiments, 16HBE cells were randomly assigned to four groups: cell blank group, cell model group [treated with 50 μg·L^-1 interleukin(IL)-13], cell experimental group (treated with 65 μmol·L^-1 morin+IL-13), si-NC group(transfected with si-NC, then treated with 65 μmol·L^-1 morin+IL-13) and si-MDM2 group (transfected with si-MDM2, then treated with 65 μmol·L^-1 morin+IL-13). After 48 hours of treatment, TdT mediated dUDP nick end labeling(Tunel) assay was used to detect the cell apoptosis rate; Western blot assay was performed to determine protein expression and P53 ubiquitination level.

In animal experiments, the levels of MDM2 protein in the animal control group, animal model group, animal experimental-L group, animal experimental-M and animal experimental-H group were 0.65±0.05, 0.32±0.03, 0.41±0.06, 0.46±0.04 and 0.51±0.05, respectively; the levels of BALF-IL-13 were (15.44±1.19), (55.43±3.90), (48.79±4.88), (37.25±4.59) and (25.64±1.64) pg·mL^-1, respectively; the relative expression levels of p53 mRNA were 1.00±0.14, 1.75±0.13, 1.51±0.12, 1.44±0.09 and 1.24±0.14, respectively; the relative expression levels of Bax mRNA were 1.00±0.14, 1.94±0.16, 1.75±0.17, 1.62±0.17 and 1.39±0.09, respectively; when comparing the animal model group with the animal control group, and the animal experimental-L, -M, -H groups with the animal model group respectively, the differences of the above indicators were all statistically significant (P<0.05, P<0.01). In cell experiment, the apoptosis rates of cells in cell blank group, cell model group, cell experimental group, si-NC group and si-MDM2 group were (3.94±0.27), (31.76±2.39), (19.93±1.91), (18.14±2.50) and (25.97±1.74)%, respectively; the realtive expression levels of MDM2 protein were 0.91±0.09, 0.44±0.05, 0.66±0.08, 0.68±0.05 and 0.21±0.04, respectively; when comparing the cell model group with the cell blank group, the cell experimental group with the cell model group, the si-MDM2 group with the si-NC group, the differences of the above indicators were all statistically significant (all P<0.01).

Morin may alleviate asthmatic airway inflammation and cell apoptosis by upregulating MDM2 ubiquitination to regulate p53.