Pudilan Anti-inflammatory Oral Liquid and Organic Acid Component from Taraxaci Herba Attenuate Allergic Asthma in Young Mice through Toll-like Receptor 2/Toll-like Receptor 4 Signaling Pathway

Abstract

Allergic asthma (AA) is a chronic airway inflammatory disease characterized by airway hyper-responsiveness (AHR). Pudilan anti-inflammatory oral liquid (PDL) along with its main medicinal material, Taraxaci Herba (Taraxacum mongolicum Hand.-Mazz, TH) has been widely used to treat upper respiratory tract infections. Research has shown that the major ingredient of TH, the organic acid component (OAC), possesses favorable AA activity. However, the attenuated effects of PDL and OAC from TH (TH-OAC) on AA and their possible mechanisms remain poorly understood. This study analyzed the attenuating effects of PDL and TH-OAC on AA and the underlying mechanisms. Young BALB/c mice were sensitized and stimulated to develop asthma using ovalbumin. Histological examinations were performed by hematoxylin and eosin staining. Western blotting, immunohistochemistry, and protein expression detection of toll-like receptor 2 (TLR2), TLR4, and orosomucoid 1-like protein 3 (ORMDL3) were performed to detect the presence of inflammatory components in the lung tissue. The messenger RNA (mRNA) expression levels were determined using quantitative real-time polymerase chain reaction. Results showed that PDL and TH-OAC alleviated augmented AHR and typical asthmatic pathological changes, including inflammatory infiltration and thickening of the alveolar wall. They also significantly reduced the levels of the immunoglobulin E, IL-4, IL-5, IL-6, tumor necrosis factor-α, and Nitric oxide (NO) in lung tissues of mice. Protein and mRNA expression levels of TLR2, TLR4, and ORMDL3 were downregulated following treatment with PDL and TH-OAC. PDL and TH-OAC can reduce asthma-induced inflammatory damage to the bronchi. These results provide a theoretical basis for the treatment of asthma in clinical settings.