## 4 Discussion  
We found that TQ alleviated inflammation in mice with OVA-induced AR. Particularly, TQ ethanol extract alleviated AR-related symptoms such as nasal rubbing and sneezing and histological transformations such as thickness of nasal mucosa and epithelial cells. It also reduced serum levels of Th1/2-type inflammatory cytokines and OVA-specific and total IgE. AR is characterized as a chronic inflammatory condition of the nasal mucosa, resulting from an overproduction of Th2 cytokines, including IL-4, IL-5, and IL-13, in comparison to Th1 cytokines. Eosinophils are known to cause clinical features of AR including tissue damage. IL-4 is generally produced in Th2 cells. It plays a crucial role in B cell activation and IgE antibody generation by promoting B cell differentiation and proliferation [32]. IL-5 is released by Th2 cells and mast cells [33]. It promotes the growth and differentiation of eosinophils and activates mature eosinophils [34]. IgE is mainly regulated by IL-4, IL-13, and IFN-\(\gamma\). It binds strongly to the cell surface of mast cells or basophils to secrete toxic amine compounds such as histamine and serotonin, causing severe hypersensitivity symptoms. Thus, it is an important factor in allergic reactions [35]. In this study, serum levels of TNF-\(\alpha\), IL-4, IL-5, IL-6, and IgE were significantly reduced in the group treated with 50% EtOH extract of TQ compared to the AR group (Figures 2 and 3). Also, we considered that a significant decrease in IgE levels in only a high dose of TQ 50% EtOH extract may be due to the regulation of Th2 cytokines. Only a high dose of TQ 50% EtOH extract significantly inhibited both Th2 cytokines such as IL-4 and IL-5. This result is similar to previous reports that the production of IgE is regulated by Th2 cytokines [36; 37]. These results indicate that the TQ ethanol extract can inhibit the Th1/2 cytokines and IgE, thereby suppressing inflammation and allergic reactions in rhinitis. Pathological changes such as severe submucosal edema, damage to the nasal mucosal epithelium, loss of ciliated cells, thickening of olfactory groove, and increased number of mast cells, eosinophils, and mucus-secreting goblet cells will appear in nasal mucosal tissues during AR [38]. In Figure 4, the epithelium thickness of nasal mucosa was increased due to damage caused by infiltration of eosinophil leukocytes in the nasal mucosa of the AR group. However, the group treated with TQ 50% EtOH extract showed a significant reduction of the thickness of nasal septum and epithelium in nasal mucosa compared to the AR group (Figure 4). This result means that TQ can alleviate AR by reducing pathological changes. Caffeic acid, a water-soluble natural polyphenic compound, and rosmarinic acid, an ester of caffeic acid and 3,4-dihydroxypropyllactic acid, are extensively existed in herbal medicines [39; 40]. They are commonly found in plants of the Labiatae family [41; 42; 43]. Therefore, CA and RA have been used as standard components of _Thymus_ species [44; 45]. With reference to previous reports, we analyzed both components in the ethanol extract of TQ. We found that CA and RA were present in the ethanol extract of TQ at 0.26 and 8.51 mg/g, respectively (Figure 5). Indeed, some previous studies have reported that CA has an anti-allergic effect against asthma and dermatitis [46; 47; 48]. RA can also alleviate AR in clinical trials and animal experiments [49; 50; 51; 52]. Therefore, we suggest that the therapeutic effect of TQ ethanol extract upon AR is attributed to CA and RA. The treatment goal of current medicines for AR is to rest on symptoms. Anti-histamines, anti-leukotrienes, nasal or oral glucocorticoids, and decongestants are the commonly used therapeutic options to relieve of symptoms during AR [53]. However, they have only partially inhibiting effects as well as often side effects such as headache, nasal and throat irritation, nosebleeds, and dryness of eyes, mouth, and nasal [54].