Effects of Bacillus Calmette-Guerin on airway inflammation, T helper cell differentiation and serum OVA-specific IgE levels in a mouse model of asthma
Objective To investigate the effects of Bacillus Calmette-Guerin(BCG) on airway inflamma- tion, T helper cell differentiation and serum OVA-specific IgE levels in a mouse model of asthma. Methods C57BL/6 mice were sensitized and challenged by ovabumin (OVA) as positive group(n=8), and mice were treat- ed by saline as a negative group(n=6). Mice were infected with BCG two weeks before the first OVA challenge as BCG treated group(n=8). Peribronchial and perivascular eosinophilia, goblet cell hyperplasia index and mucus overproduction index, IL-5 and IFN-γconcentrations in the supematant, T-bet and GATA-3 mRNA expression lev- els in lung tissue and serum OVA-specific IgE levels were tested. Results Peribronchial and perivascular eosino- philia of BCG treated group was (65.09±32.58)/mm~2, which was significantly depressed compared to that in positive group (941.86±592.03)/mm~2 (P0.05). Goblet cell hyperplasia index in BCG treated group was lower than that in positive group [(19.25±12.27)/mm vs (54.39±24.50)/mm, P0.001]; mucus overproduction index in BCG treated group was also lower than that in positive group [(6.47±3.94) % vs (15.53±11.38)%, P0.001]. The concentration of IL-5 was lower in BCG treated group than that in positive group [(83.40±11.33) pg/ml vs (192.30±44.30) pg/ml, P0.01]. The concentration of IFN-γwas higher in BCG treated group than that in positive group [(28.69±6.05) pg/ml vs (18.12±3.78) pg/ml, P0.01]. The ratio of T- bet and GATA-3 mRNA was higher in BCG treated group than that in positive group [(1.02±0.18) vs (0.74±0.07), P0.01]. The level of serum OVA-specific IgE was lower in BCG treated group as comparing group [(0.61±0.27) vs (1.05±0.45), P0.05]. Conclusion These findings suggest that BCG can inhibit airway eosinophilia and mucus overproduction, influence the expression of T-bet and GATA-3, depress the expression of IL-5, elevate the expression of IFN-γand inhibit serum OVA-specific IgE levels in a mouse model of asthma.