[The preventive effect of bacillus Calmette-Guerin vaccination in early life on airway inflammation and mucus production in a murine model of asthma].

OBJECTIVE

To investigate the preventive effect of bacillus Calmette-Guerin (BCG) vaccination in early life on airway inflammation and mucus production in a murine model of asthma.

METHODS

Twenty-five newborn C57BL/6 mice were divided into three groups including group A (saline sensitized/challenged mice, n = 8), group B [ovalbumin (OVA) sensitized/challenged mice, n = 9], group C (OVA sensitized/challenged mice treated by BCG in early life, n = 8). Mice in group C were subcutaneously injected by 25 microl BCG (10(3) CFU) four times at 0 week, 1st week, 2nd week and 3rd week of age respectively, while mice in group A and B were injected by the same volume of saline solution. Mice were sensitized on day 42 and 56 by saline (group A) or OVA (group B and C) and challenged from day 66 to 68 by saline (group A) or OVA (group B and C) repeatedly. Samples were collected at 48 h after the last OVA challenge. The outcome measurements included eosinophil count in bronchoalveolar lavage fluid (BALF), periodic acid-schiff reaction (PAS) staining of lung tissues, the goblet cell hyperplasia ratio (HR) and the epithelial cell mucus occupying ratio (MOR). The mRNA expression of mucus gene (MUC5AC) was measured by reverse trancription-polymerase chain reaction (RT-PCR).

RESULTS

The total cells in BALF in group B (123.8 +/- 14.5) x 10(4)/ml] and that in group C [(77.4 +/- 14.1) x 10(4)/ml] were increased significantly as compared with that in group A [(15.0 +/- 1.4) x 10(4)/ml, P < 0.01, P < 0.01], but there was no significant difference between group B and group C (P > 0.05). The number of eosinophils in BALF in group B [(78.220 +/- 11.770) x 10(4)/ml] and that in group C [(24.430 +/- 7.020) x 10(4)/ml] were increased significantly when compared with that in group A [(0.090 +/- 0.020) x 10(4)/ml, P < 0.01, P < 0.05], and that in group C was significantly reduced when compared with that in group B (P < 0.01). The HR and MOR in group B [(41.80 +/- 4.09)/mm, (28.43 +/- 2.75)% respectively] and those in group C [(21.58 +/- 5.09)/mm, (9.43 +/- 2.30)% respectively] were increased significantly when compared with those in group A [(3.00 +/- 1.20)/mm, (0.75 +/- 0.29)% respectively, P < 0.01, P < 0.01], but those in group C were significantly reduced when compared with those in group B (P < 0.01). The mRNA expression of MUC5AC in group B (1.07 +/- 0.03) and that in group C (0.86 +/- 0.05) were increased significantly when compared with that in group A (0.64 +/- 0.08, P < 0.01, P < 0.01), but that in group C were significantly reduced when compared with that in group B (P < 0.01).

CONCLUSION

BCG vaccination in early life can inhibit the development of airway inflammation and mucus production in a murine model of asthma.