OBJECTIVEThis work was intended to investigate the effect of acrolein fog exposure on the ratio of CD4⁺CD25⁺ regulatory T cells (Treg) and expression of transcription factor Foxp3 in asthmatic rats.

METHODSSixty 6 - 8 weeks male Wistar rats were randomly divided into 4 groups according to random number table (15 rats for each group) which were control group (animals were treated with saline), aerosolized ovalbumin (OVA) exposure group, acrolein exposure group and combined OVA and acrolein fog exposure group, respectively. The rats were exposed to air or/and to saline or OVA aerosol for 6-8 weeks respectively.24 h after the last challenge, 4 ml of peripheral blood and lung tissue were collected from each rat. The percentage of CD4⁺CD25⁺ T cells was determined by flow cytometry analysis. The concentration of interleukin-4 (IL-4) and γ-interferon (IFN-γ) in peripheral blood and lung homogenates were measured by ELISA. The protein expression of Foxp3 in the lung was detected by Western blotting.

RESULTSThe percentage of CD4⁺CD25⁺T cells in aerosolized OVA group ((6.23 ± 1.11)%) was significantly lower than that in the normal saline group ((9.97 ± 1.23)%) (P < 0.01). The percentage of CD4⁺CD25⁺ T cells ((3.26 ± 0.84)%) in OVA combined acrolein fog exposure group was remarkably lower than that in the aerosolized OVA exposure group and in the normal saline group (P < 0.01). IL-4 in both plasma and lung ((22.57 ± 4.34), (0.86 ± 0.12) ng/L) was significantly increased in the OVA exposed rats compared with the normal saline group ((11.57 ± 2.86), (0.31 ± 0.10) ng/L) (P < 0.01). Further remarkable increase in IL-4 of both plasma and lung tissue was observed in the group exposed to both OVA and acrolein ((34.32 ± 6.21), (1.45 ± 0.32)ng/L) compared with the aerosolized OVA exposure group and the normal saline group (P < 0.05). γ-IFN of plasma and lung tissue in OVA exposed group ((59.67 ± 20.12), (0.56 ± 0.17) ng/L) was significantly decreased compared with the normal saline group ((151.74 ± 56.68), (1.54 ± 0.21) ng/L) (P < 0.01), and a further remarkable decrease in IFN-γ of plasma and lung tissue was observed in the group exposed to both OVA and acrolein ((10.12 ± 2.57), (0.49 ± 0.10) ng/L) compared with the aerosolized OVA exposure group and the normal saline group (P < 0.05). Protein expression of Foxp3 in the aerosolized OVA group (8.07 ± 0.24) was lower than that in the normal saline group (10.25 ± 0.31) (P < 0.01), while the protein expression of Foxp3 in OVA combined acrolein fog exposure group (6.38 ± 0.32) was lower than that in the normal saline group and the aerosolized OVA exposure group (P < 0.01).

CONCLUSIONThe number of CD4⁺CD25⁺ Treg cells and the expression of Foxp3 were likely to be altered by acrolein fog exposure, which might play an important role in acrolein induced Th1/Th2 imbalance in asthmatic rats.