## 4 Discussion
It can be regarded as another possible mechanism for their expectorant activities. The lung weight index, defined as the proportion of lung weight to body weight, is commonly regarded both generally and biochemically as a reliable indicator of vascular permeability and edema [37,58]. Similar to the ovalbumin-induced asthmatic mouse model [59], mice exposed to PM\({}_{2.5}\) through instillation methods demonstrated increased microvascular leakage, leading to heightened lung congestion and edema [2,3]. In the present study, noticeable lung focal congestion with enlargement was also observed in the PM\({}_{2.5}\) control mice relative to the intact vehicle control upon gross inspection. Remarkable increases in gross congestional regions (%), as well as lung relative and absolute weights, were observed in the PM\({}_{2.5}\) control relative to the intact vehicle controls. However, noticeable decreases in gross congestional regions (%) and lung absolute and relative weights were noticed in all AJ (400-100 mg/kg)-supplied mice in a dose-dependent manner. Notably, mice treated with 400 mg/kg of AJ exhibited beneficial inhibitory effects on PM\({}_{2.5}\)-induced lung congestion, enlargement, and the corresponding increases in both absolute and relative lung weights, similar to the effects seen with 250 mg/kg of AX. These findings suggest that the oral supply of AJ from 400 to 100 mg/kg effectively inhibited the PM\({}_{2.5}\)-induced lung congestive edema and the associated elevations in lung index relative to the impact of AX at 250 mg/kg. The effects were particularly pronounced in the AJ (400 mg/kg) group, indicating a dose-dependent response, potentially via promising mucolytic, expectorant, or anti-inflammatory effects. The histomorphometric index, ASA (%/mm\({}^{2}\)), is indicative of pulmonary function and gas exchange capacity, with decreases suggesting reduced lung surface area and capacity, which are commonly seen in various lung diseases [18,19,24,37,60]. PAS staining identifies mucous-producing cells, with a higher intensity indicating greater activity [18,19,61] and increased bronchial mucosa thickness, and PAS+ cells associated with expectorant effects [16,17,18,19]. Apoptosis, a regulated process causing cell death, is marked by chromatin condensation and apoptosis, with cleaved caspase-3 as a key executioner [62]. PM\({}_{2.5}\) exposure increases cleaved caspase-3 in lung tissue, indicating apoptosis and damage [63, 64], while oxidative stress from PM\({}_{2.5}\) interrupts the oxidative defense system and mediates mitochondria-dependent apoptosis [65]. COX-2, an enzyme crucial for prostaglandin synthesis and inflammation, is also involved in lung damage induced by PM\({}_{2.5}\)[66, 67]. Decreased COX-2 immunoreactivity signals the beneficial effects of treatments on inflammation [68, 69]. In mice, PM\({}_{2.5}\)-induced pulmonary injuries include inflammatory cell infiltration and alveolar septum thickening [2, 3, 70, 71], with histopathological observations showing hyperplasia of PAS+ mucus-producing cells, decreased ASA, increased bronchial mucosa thickness, and elevated cleaved COX-2 and caspase-3 activity after PM\({}_{2.5}\) exposure. Oral supply of AJ (400-100 mg/kg) increased ASA and decreased septal thickness, inflammatory infiltration, and apoptosis markers in a dose-dependent manner, with AJ at 400 mg/kg showing effects comparable to AX at 250 mg/kg. AJ also increased PAS+ cell numbers and bronchial mucosa thickness, indicating potent expectorant activity [16]. These findings indicate that AJ offers substantial pulmonary protection against PM\({}_{2.5}\)-induced injuries through its anti-inflammatory and mucolytic properties, supporting its potential as a candidate for respiratory health products. These results align with previous studies demonstrating AJ's protective effects against human diseases [23, 32, 33].