# Evaluation of Yukmiijihwang-Tang as a Novel Preventive Agent in Ovalbumin-Induced Murine Asthma
## 4 Discussion  
In this study, we explored the potential effects of YJT against an OVA-induced murine model of asthma. YJT exhibited inhibitory effects on inflammatory cell infiltration and cytokine production in BALF and lung tissues, significantly mitigated the mucus production and oxidative stress caused by OVA, and downregulated NF-kB phosphorylation in lung tissues. Asthma, which is characterized by persistent airway inflammation, is a chronic respiratory disease. Its etiology involves the multifaceted interplay of diverse factors that generate intricate pathogenic mechanisms [31]. When introduced into the respiratory system, ovalbumin serves as a specific allergen, stimulating the bronchial epithelium to produce TSLP via the NF-kB signaling pathway [32]. TSLP elicits immune responses, including T-cell sensitization [33], and the T cells initiate a Th2-cell response characterized by GATA3-mediated NF-kB signaling [34]. This cascade prompts the inflammation-provoking secretion of various cytokines, including IL-4, IL-5, and IL-13, which are pivotal for the initiation of airway inflammation [35]. IL-4 triggers the upregulation of vascular cell adhesion molecule (VCAM)-1 on vascular endothelial cells to promote the migration of lymphocytes, monocytes, and eosinophils to inflammatory sites. It additionally enhances eosinophilic inflammation by amplifying chemotaxis and elevatingotaxin expression [35; 36]. IL-5 also regulates the migration and survival of eosinophils. Upon activation by IL-5, eosinophils undergo degranulation and release cytokines with antimicrobial effects that induce damage to adjacent cells and tissues [37]. IL-13 critically influences IgE synthesis, leading to excessive mucus production and airway hyperresponsiveness [38]. Meanwhile, the inflammatory cytokine TNF\(\alpha\) is secreted by antigen-activated M1 macrophages [39]. TNF\(\alpha\) induces mast cells to produce histamine and serves as a chemoattractant for neutrophils and eosinophils, making it a crucial factor in inflammation [40]. Direct stimulation by IL-13 and TNF\(\alpha\) increases the production of TSLP by epithelial cells [28; 41]. This enhanced TSLP prompts Th2 cells to increase cytokine secretion, thereby exacerbating asthma symptoms [28; 42]. Here, we show that the administration of YJT significantly decreased inflammatory cell infiltration into lung tissues, inflammatory cell counts in BALF, and the production of Th2 cytokines and other related cytokines in BALF. These findings strongly suggest that YJT can suppress the inflammatory response associated with asthma. Figure 8: Effect of YJT on phospho-NF-kB activity in lung tissues. Phospho-NF-kB, NF-kB, and \(\beta\)-actin expression in lung tissues was assessed by Western blotting. NC, negative control; OVA, ovalbumin-exposed mice; OVA+DEX, dexamethasone administered and ovalbumin-exposed mice; OVA+YJT100, YJT (100 mg/kg) and ovalbumin-exposed mice; OVA+YJT300, YJT (300 mg/kg) and ovalbumin-exposed mice. Results are presented as means \(\pm\) SD (\({}^{\pi}\)_p_\(<\) 0.05 compared with the NC group; \({}^{\pi}\)_p_\(<\) 0.05, \({}^{\pi\ast}\)_p_\(<\) 0.01 compared with the OVA group). The Th2 inflammatory response contributes to increasing mucus secretion by upregulating glycoprotein, which is the main component of mucin [35]. Th2 interleukins also contribute to MUC5 AC expression via NF-\(\kappa\)B signaling within goblet cells [43]. IL-4 stimulates mucin production by goblet cells and airway epithelial cells [44], while IL-5 enhances eosinophil recruitment to further stimulate goblet cells [37]. IL-13 not only induces goblet cell hyperplasia but also impairs their ciliary functions [45]. Together, these cytokines create a situation that enhances mucus production, which exacerbates respiratory symptoms by causing airway obstruction, persistent coughing, and breathing difficulty. The excess mucus also traps irritants, leading to further inflammation and contributing to the severity of asthma [46].