Additionally, the NF-B pathway is important in eosinophil activation and survival [44]. those observed in the saline-treated control mice. As shown in Figure 2BC2G, the OVA-induced increases in these cytokines in both BALF (Figure 2BC2D) and lung tissues (Figure 2EC2G) were significantly reduced by the administration of Baicalein. We further explored the effect of Baicalein on the Th2 response by assessing the mRNA expression levels of these cytokines. As shown in Figure 3AC3C, the administration of Baicalein relieved the OVA-induced increase in IL-4, IL-5, and IL-13 mRNA expression levels. Open in a separate window Figure 2 Baicalein reduces OVA-induced Th2 inflammation. The OVA/Al(OH)3 model is characterized by Th2-driven airway inflammation. To determine the effect of Baicalein on Th2 airway inflammation, ELISA was performed to detect the levels of IgE in serum (A) and IL-4, IL-5, and IL-13 in BALF (BCD) and lung homogenate (ECG) (results are presented as the mean SEM. n = 6 mice per group; ## 0.01 compared with the control group; 0.05, 0.01 compared with the OVA/Vehicle group). Open in a separate window Figure 3 Baicalein inhibits OVA-induced IL-4, IL-5, and IL-13 expression at the mRNA level. The mRNA levels of IL-4 (A), IL-5 (B), and IL-13 (C) were determined by using RT-qPCR and were normalized to those of -actin. (Results are presented as the mean SEM; n = 6 mice per group. 0.01 vs the control group; 0.05, 0.01 vs the OVA/Vehicle group). Baicalein suppresses OVA-induced inflammatory cell recruitment To further determine the effect of Baicalein on OVA-induced airway inflammation, hematoxylin and eosin (H&E) staining was conducted. As shown in Figure 4A and ?and4B,4B, Baicalein markedly relieved the infiltration of inflammatory cells into the peribronchiolar and perivascular connective tissues. Furthermore, asthmatic mice after OVA inhalation presented thickened airway walls and confined lumens and shed tracheal epithelial cells, suggesting that Baicalein treatment relieves these pathologic changes. Open in a separate window Figure 4 Baicalein suppresses OVA-induced inflammatory cell recruitment. (A) Histologic lung sections were stained with H&E, which showed that Baicalein reduces inflammatory cell recruitment and infiltration into the airway. Image are shown at 200 magnification with a scale bar representing 100 m. (B) Lung inflammatory scores were assessed by histological analysis of lung tissues. STA-21 Baicalein reduced the numbers of total cells (C) and eosinophils (D) in BALF following OVA STA-21 challenge (Results are presented as the mean SEM. n = 6 mice per group; 0.01 compared with STA-21 the control group; 0.05, 0.01 compared with the OVA/Vehicle group). BALF was collected 24 h after the last OVA aerosol challenge, EBR2 and the total and differential cell counts were determined. OVA challenge significantly increased the total cell (Figure 4C) and eosinophil counts (Figure 4D) in BALF compared to those in control mice. The oral administration of Baicalein drastically decreased the total cell and eosinophil counts compared to those in the saline-administered control mice. Baicalein attenuates OVA-induced mucus production The formation of mucus in small and large bronchioles is an important aspect of allergic lung inflammation, and goblet cell hyperplasia and submucosal gland hypertrophy in asthmatic airways can be seen even in some patients with newly diagnosed asthma [28]. As visualized by Periodic Acid Schiff (PAS) staining, OVA exposure increased mucus production by airway epithelial cells (Figure 5AC5B). However, Baicalein treatment significantly decreased the production and secretion of mucus. In.