## 3 Results  
### Revealing the Impact of Allergen Exposure on Epithelial Barrier Integrity Through TEER Monitoring  
Transepithelial electrical resistance measurements were employed to assess the integrity of the bronchial epithelial barrier following exposure to various allergen conditions. TEER values, expressed as percentages relative to the pre-exposure baseline, were recorded at multiple time points over a 72 h period (Figure 3) to evaluate the extent of epithelial barrier disruption. At the 72-h mark, the degree of epithelial resistance alteration was quantified as a percentage of the pre-exposure values, providing a comparative measure of barrier integrity loss. Every experimental group demonstrated statistically significant differences in TEER values when compared to the control group. Furthermore, an interesting remark is that all groups exhibit an initial TEER increase within the first four hours, followed by a clear and progressive decline at later time points. The dose-response relationship observed among the combined HDM+RW (HR) exposure groups revealed that HR 100 demonstrated a significant decrease of 51.86% \(\pm\) 4.98% compared to the pre-exposure TEER values (\(p<0.0001\)), while HR 50 exhibited a more modest decline of 68.81% \(\pm\) 3.27% (\(p=0.0001\)). The HR 25 group showed the least impairment, with TEER values of 79.71% \(\pm\) 4.42% (\(p=0.01\)). Therefore, higher concentrations of HR (HR100 and HR50) lead to a significant decrease in TEER over time, indicating a loss of epithelial barrier integrity. The data presented are illustrated in Figure 3A. These findings suggest that higher concentrations of RW and HDM allergen extracts lead to a more pronounced reduction in epithelial barrier integrity. Statistically, no significant difference was observed between HR 25 and HR 50. However, significant differences were found between HR 25 and HR 100 (\(p<0.0001\)), as well as between HR 50 and HR 100 (\(p<0.05\)). To further investigate the impact of specific allergenic proteins, exposures to preparations containing the allergenic molecules from these extracts were assessed. The DAM 100 condition, which included Der p 1, Amb a 1, Amb a 11 and Amb a 12 corresponding to 100 ug/mL allergen extracts, resulted in a significant TEER reduction of 64.95% \(\pm\) 5.05% (\(p<0.0001\)). In contrast, the DAM 50 condition (corresponding to 50 ug/mL of allergen extract) led to a more modest reduction in TEER values of 76.54% \(\pm\) 4.17% (\(p<0.01\)). Interestingly, AM 100 containing only the mixture of ragweed allergens (Amb a 1, Amb a 11 and Amb a 12) corresponding to 100 ug/mL of allergen extract exhibited TEER values of 74.15% \(\pm\) 6.14% (\(p<0.01\)), suggesting that the inclusion of Der p 1 may enhance the barrier-disrupting effects when combined with ragweed allergens. The data are graphically depicted in Figure 3B. Exposure to RW 200 led to a reduction in TEER, with values decreasing to \(52.14\%\pm 4.88\%\) relative to the baseline (\(p\) = 0.0001). In contrast, HDM 200 exposure resulted in a more pronounced decline in TEER values (47.87% \(\pm\) 3.91%, \(p\) = 0.0001), indicating a stronger effect of HDM on epithelial barrier modulation. Notably, the combined HR 200 condition produced the most significant reduction in TEER (44.18% \(\pm\) 6.19%, \(p\) = 0.0001), suggesting that the synergistic interaction between RW and HDM allergens exerts a more substantial impact on epithelial permeability than either allergen alone at the same concentration. The corresponding data are displayed in Figure 3C. The TEER reduction induced by the positive control, the 5% Triton-X, on NHBE cells was assessed at 30 min post-treatment, revealing an extreme decline in barrier integrity (8.21% \(\pm\) 2.14%, \(p\) < 0.0001).