Ginkgolide A reduces airway inflammation in a neutrophil-predominant murine model of asthma via suppression of immune response of helper T cell 17 / 中国中西医结合急救杂志

ABSTRACT

Objective To determine the effects of ginkgolide A (GA) in a neutrophil-predominant murine model of asthma and explore underlying mechanisms. Methods Thirty-five female BALB/c mice were randomly divided into sham operation group (Sham group), asthma group, dexamethasone intervention control group (DEX group), low dose GA intervention group (L-GA group) and high dose GA intervention group (H-GA group), with 7 mice in each group. The asthma model was induced by intraperitoneal injection of 20 μg ovalbumin (OVA) and 75 μL Fluorine complete adjuvant (FCA) on day 0, 14 and 21, and challenged 30 minutes with 5% OVA atomization on days 22-24 consecutively; phosphate buffer (PBS) was sensitized and stimulated in Sham group. The mice in L-GA group and H-GA group were intraperitoneally injected with GA of 40 mg/kg and 80 mg/kg at 1 hour before each challenge, while the mice in DEX group were intraperitoneally injected with dexamethasone of 1 mg/kg. After 24 hours of the last OVA stimulation, the airway resistance was measured at the time of 0, 3, 6, 12, 25, 50 g/L acetylmethacholine aerosol stimulation. The total number of cells and cell classification in bronchoalveolar lavage fluid (BALF) were counted. The transforming growth factor-β1 (TGF-β1) and interleukin-17 (IL-17) in BALF were detected by enzyme linked immunosorbent assay (ELISA). The proportion of helper T cell 17 (Th17) to CD4+ T cell in lung tissue was detected by flow cytometry, and the pathological characteristics of lung tissue were evaluated. Results Compared with the Sham group, the airway hyper responsiveness (AHR), the total cells, the neutrophil counts, the levels of TGF-β1, IL-17 in BALF, and the proportion of Th17 cells in the lung tissue in the asthma group were significantly increased, obvious inflammatory cell infiltration and collagen fiber deposition around airway were observed, and airway inflammation score and mucus score were significantly increased. Compared with the asthma group, low and high doses of GA significantly reduced AHR, and there was a significant difference in airway resistance at the time of 50 g/L acetylmethacholine stimulation (cmH2O·s-1·mL-1 5.29±0.40, 3.99±0.57 vs. 7.34±0.77, both P < 0.05); the total cells, neutrophil counts, and levels of TGF-β1, IL-17 in BALF, and the proportion of Th17 cells in lung tissue were significantly decreased [total cells count (×104/L) 21.00±1.00, 17.00±1.02 vs. 27.50±2.50; neutrophil count (×104/L) 12.600±0.600, 10.610±0.210 vs. 16.875±1.125; TGF-β1 (ng/L) 371.40±107.80, 289.60±70.76 vs. 551.90±68.34; IL-17 (ng/L) 60.75±11.79, 44.77±7.09 vs. 122.50±38.87; the proportion of Th17 cells (5.53±0.40)%, (3.76±1.10)% vs. (8.30±1.19)%, all P < 0.05]; inflammatory cell infiltration around the airway and mucus secretion was significantly reduced, airway inflammation score and mucus score were significantly decreased (2.16±0.28, 1.16±0.28 vs. 3.77±0.25; 1.33±0.58, 1.17±0.29 vs. 3.67±0.58, all P < 0.05). The AHR, total cells, neutrophil counts, and IL-17 level in BALF, the proportion of Th17 cells in lung tissue and airway inflammation score decreased more obviously with the increase of GA dosage (all P < 0.05). For index mentioned above, no significant differences were observed between DEX group and asthma group. Conclusion GA treatment was effective in a murine model of neutrophil-predominant asthma via inhibiting response in the immune cells Th17.