Aqueous extract of Gumiganghwal‐tang, traditional herbal medicine, reduces pulmonary fibrosis through transforming growth factor‐β1/Smad signaling pathway in murine model of chronic asthma

Abstract

Gumiganghwal‐tang is a traditional herbal prescription that is widely used for the treatment of the cold and inflammatory diseases in Korea and other Asian countries. In this study, we investigated the protective effects of aqueous extract of Gumiganghwal‐tang (GGTW) against airway inflammation and pulmonary fibrosis using a mouse model of chronic asthma. Chronic asthma generated by sensitizing and inhalation BALB/c mice with intraperitoneal injection and nebulized 1% ovalbumin (OVA) for 4 weeks. GGTW (100 mg/kg or 200 mg/kg) was also administered by oral gavage once a day for 4 weeks. We investigated the production of Th2 cytokines, chemokine and transforming growth factor (TGF)‐β 1 in bronchoalveolar lavage fluid (BALF), the levels of immunoglobulin (Ig)E in plasma, and the expression of TGF‐β 1, Smad‐3 and collagen in lung tissue. Our results revealed that GGTW decreased the production of Th2 cytokines, chemokine and TGF‐β 1 in BALF, and attenuated levels of total and OVA‐specific IgE in plasma. Moreover, GGTW significantly reduced the expression of TGF‐β 1, Smad‐3 and collagen deposition in lung tissue. These results indicate that GGTW reduces the airway inflammation and pulmonary fibrosis via regulation of Th2 cytokines and TGF‐β1/Smad‐3 pathway, providing a potential treatment for chronic asthma.