OBJECTIVEOver the past several decades, there has been a significant increase in allergy and asthma in the world, which correlates with alterations in microflora and widespread use of antibiotics. The authors have developed a mouse model of antibiotics-induced microbiota disruption. In that model, mice were challenged by intranasal exposure to Aspergillus fumigatus allergens to explore the relation of allergic airway response and intestinal microflora disruption.

METHODSSixty female BALB/c mice were divided at random into 6 groups with 10 mice in each. (1) First antibiotic therapy group: the mice were given oral cefoperazone for 7 days, on day 7, mice were inoculated with Candida albicans (10(9)/ml, 50 microl) orally. (2) First control group: the mice were treated as first antibiotic therapy group, but cefoperazone and Candida albicans were replaced by saline. The mice in groups (1) and (2) were sacrificed on day 8, and cecal contents were collected for quantitative analysis of the intestinal bacterial flora. (3) Antibiotic therapy and challenge group: the mice were treated as the first antibiotic therapy group, then challenged (day 9 and 16) by intranasal exposure to Aspergillus fumigatus allergen. (4) Second antibiotic therapy group: the mice were treated as the first antibiotic therapy group, then challenged (day 9 and 16) by intranasal exposure to saline. (5) Challenge group: the mice were treated as the first control group, then challenged (day 9 and 16) by intranasal exposure to Aspergillus fumigatus allergen. (6) Second control group: the mice were treated as the first control group, then challenged (day 9 and 16) by intranasal exposure to saline. The mice in (3) - (6) group were killed for analysis of allergic airway response on day 19.

RESULTSThe quantity of Enterobacteriaceae, Enterococcus, Bifidobacterium and Lactobacillus in first antibiotic therapy group was significantly lower than that in the first control group, the quantity of Candida albicans increased in the first antibiotic therapy group as compared with the first control group. Mice intestinal microflora were disrupted with weight reduction and increased moisture in feces. After challenging with Aspergillus fumigatus allergens via intranasal inhalation, the total cell count, eosinophils, lymphocytes and neutrophils increased in BALF, especially in bronchoalveolar lavage fluid (BALF) from the mice in antibiotic therapy and challenge groups. IL-4 level in BALF from antibiotic therapy and challenge group (45.35 +/- 2.36) pg/ml was higher than that in the second control group (35.32 +/- 2.53) pg/ml. The expression of GATA-3 mRNA in the mice lung tissue (0.569 +/- 0.023) was higher than that in the second control group (0.410 +/- 0.020), and the ratios of T-bet/GATA-3 (0.578 +/- 0.021) decreased as compared with that in the second control group (0.804 +/- 0.035). IFN-gamma level in BALF from any group was not significantly different. In the absence of antibiotics, mice exposed to Aspergillus fumigatus allergen did not develop an allergic response in the airways.

CONCLUSIONSThe allergic (Th2) immune response can be induced by airway challenge with Aspergillus fumigatus allergen in the mice in which the intestinal microflora disruption resulted from antibiotic therapy, this result suggests that the intestinal microflora disruption resulted from antibiotic therapy is a risk factor for allergy and asthma.