OBJECTIVE

To investigate the efficacy and mechanism of subcutaneously given recombinant Der p 2 entrapped PLGA nanoparticles (DEPN) on mouse model with allergic airway inflammation.

METHODS

40 BALB/c mice were randomly divided into 5 groups, group A (normal control) were treated with saline (100 microl) all the time, groups B, C, D and E were sensitized intraperitoneally with crude dust mite extracts (10 microg) and then subcutaneously treated respectively with PBS (100 microl), 2 mg empty PLGA (EP), 100 microg rDerp2, and 2 mg DEPN (loaded with 100 microg rDerp 2) for 3 times, once per day, followed by intranasal challenge of 50 microg rDer p 2. One day post challenge, mice were sacrificed and bronchoalveolar lavage fluid (BALF) was collected. Number of the total cells and eosinophils was determined, and airway inflammation and mucus secretion were analyzed by haematoxylin and eosin (H&E) staining and periodic acid-Schiff (PAS) staining. Level of cytokines in the supernatant of splenocyte culture was assayed by ELISA. Level of rDer p 2 specific IgG2a and IgE in the sera was determined by ELISA.

RESULTS

The lung histology showed development of eosinophil infiltration in the airway of mice in groups B and C. The lung inflammation and mucus secretion in groups D and E were significantly alleviated than that of groups B and C. Number of total cells (63.50+/-5.12) and eosinophils (15.32+/-3.04) in BALF decreased in group B. Compared with group B, the number of total cells in groups D (55.3+/-5.20) x 10(4) /ml and E (41.00+/-4.91) x 10(4)/ml greatly decreased (P<0.05), and same with that of eosinophils in groups D (9.56+/-1.09) x 10(4) /ml and E (3.22+/-0.31) x 10(4)/ml. The rDerp 2 specific IgE and IgG2a antibodies in group B were 1.14+/-0.105 and 0.14+/-0.07 respectively. The level of specific IgE was significantly lower (P<0.01) in groups D (0.93+/-0.04) and E (0.77+/-0.09), and that of IgG2a in groups D (1.02+/-0.01) and E (1.17+/-0.46) were significantly higher (P<0.01) than that in group B. The level of IL-4 and IFN-gamma in BALF in group B were (78.90+/-6.07) pg/ml and (27.30+/-3.51) pg/ml respectively. IL-4 in groups D and E was (55.6+/-3.79) pg/ml and (48.6+/-4.50)pg/ml respectively, significantly lower (P<0.01) than that of group B; while IFN-gamma (68.50+/-2.87) pg/ml in group E was significantly higher than that of group B (P<0.01). IL-4 released from cultured splenocytes in groups D and E was (56.30+/-4.85) pg/ml and (40.20+/-4.36) pg/ml respectively, significantly lower than that in group B (81.2+/-6.84 pg/ml) (P<0.01). The released IFN-gamma in group E was (70.20+/-3.85) pg/ml, significantly higher than in group B (34.60+/-2.25) pg/ml (P<0.01).

CONCLUSION

DEPN can inhibit airway allergic inflammation, its mechanism may be relevant to a balance of Th1 and Th2.