Anti-allergic and anti-inflammatory effects of Gastrodia elata Blume extract in ovalbumin-induced asthma rat model.

Background: Allergic asthma is a chronic inflammatory disease in which bronchial inflammation causes narrowing of the bronchi when exposed to allergens, resulting in coughing, wheezing, and difficulty breathing. Gastrodia elata Blume (GEB) is a perennial Orchidaceae plant native to alpine areas and is known to be effective in anti-inflammatory and anticonvulsants. This study evaluated the anti-inflammatory and anti-allergic effects of GEB extract in a rat model of allergic asthma induced by ovalbumin. This study evaluated the anti-inflammatory and anti-allergic effects of GEB extract in a rat model of allergic asthma induced by ovalbumin. Twenty-four 6-week-old Wistar rats were divided into three groups: control group (CON), ovalbumin (OVA) -induced group, and GEB treatment group. Except for the CON group, the remaining groups were sensitized to OVA by intraperitoneal injection, and asthma was induced by OVA intranasal instillation. The CON and OVA groups were administered distilled water, and the GEB group was administered 7 g/kg of GEB extract for 11 days.

Results: Serum total IgE levels were decreased in the GEB group compared to the OVA group. Also, lung IL-4, IL-5, and IL-13 levels were significantly lower in the GEB group than in the OVA group. Histopathological analysis using hematoxylin and eosin and periodic acid Schiff staining, the tracheal and alveolar walls of the OVA group were thickened, and there was increased infiltration of inflammatory cells in the bronchi, perivascular, and alveolar spaces. As for lung damage caused by OVA, GEB treatment reduced the infiltration of inflammatory cells into the bronchi and blood vessels, and the alveolar spaces were maintained, showing a structure similar to that of the CON group. Immunohistochemical analysis showed that IL-4, IL-5, CD206, and MPO expression levels were reduced in the GEB group compared to the OVA group.

Conclusions: This suggests that GEB treatment has an anti-inflammatory and anti-allergic effect by reducing the levels of IgE and the cytokines IL-4, IL-5, and IL-13 and ameliorating histopathological changes in an asthma rat model.