[Effects of ozone exposure on percentage of CD4(+)CD25(high)Foxp(3+) regulatory T cells and mRNA expression of Foxp3 in asthmatic rats].
OBJECTIVE
To investigate the effects of low-concentration ozone exposure on the percentage of CD4(+)CD25(high)Foxp(3+) regulatory T cells and the mRNA expression of transcription factor Foxp3 in asthmatic rats.


METHODS
Sixty male Wistar rats were randomly divided into 4 groups (n = 15 for each): normal control group, ovalbumin (OVA) exposure group, ozone exposure group, and OVA+ozone exposure group. The OVA exposure group was sensitized and challenged with OVA to establish an asthma model; the normal control group inhaled aerosolized saline; the ozone exposure group inhaled low-concentration ozone; the OVA+ozone exposure group inhaled low-concentration ozone before being challenged with aerosolized OVA every day. The percentage of CD4(+)CD25(high)Foxp(3+) regulatory T cells in CD4(+) T cells was determined by flow cytometry. The levels of interferon-γ (INF-γ) and interleukin 4 (IL-4) in peripheral blood and lung tissue were measured by enzyme-linked immunosorbent assay. The mRNA expression of Foxp3 in lung tissue was measured by PCR.


RESULTS
The percentages of CD4(+)CD25(high)Foxp(3+) regulatory T cells in OVA exposure group (6.12±1.03%) and ozone exposure group (5.87±1.26%) were significantly lower than that in normal control group (9.85±1.34%), and the percentage of CD4(+)CD25(high)Foxp(3+) regulatory T cells in OVA+ozone exposure group (3.31±0.85%) was significantly lower than those in normal control group and OVA exposure group (P < 0.01). The levels of IL-4 in plasma and lung tissue in OVA exposure group (plasma: 21.83±5.12 ng/L; lung tissue: 0.89±0.13 ng/L) were significantly higher than those in normal control group (plasma: 10.58±2.73 ng/L; lung tissue: 0.32±0.11 ng/L) (P < 0.01). The levels of IL-4 in plasma and lung tissue in OVA+ozone exposure group (plasma: 35.47±7.24 ng/L; lung tissue: 1.50±0.42 ng/L) were significantly higher than those in normal control group and OVA exposure group (P < 0.01). The levels of INF-γ in plasma and lung tissue in OVA exposure group (plasma: 61.78±23.45 ng/L; lung tissue: 0.69±0.21 ng/L] were significantly lower than those in normal control group [plasma: 158.89±60.23 ng/L; lung tissue: 1.86±0.29) (P < 0.01). The levels of INF-γ in plasma and lung tissue in OVA+ozone exposure group (plasma: 10.28±2.63 ng/L; lung tissue: 0.41±0.12 ng/L) were significantly lower than those in normal control group and OVA exposure group (P < 0.01). The mRNA expression of Foxp3 was significantly lower in the OVA+ ozone exposure group than in the normal control group (P < 0.05).


CONCLUSIONS
Low-concentration ozone exposure may decrease the number of CD4(+)CD25(high)Foxp(3+) regulatory T cells and inhibit the mRNA expression of Foxp3 to promote Th1/Th2 imbalance in asthmatic rats, suggesting that ozone exposure may be one of factors that induce asthma attack.
Department of Clinical Laboratory, The fifth Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China.
Ming
M
Wei
Ling
L
Tu
Ying-hong
YH
Liang
Jia
J
Liu
Yan-jie
YJ
Gong
Jun-hua
JH
Zhang
Yi-hua
YH
Zhang
D000818:Animals; D001249:Asthma / Q000378:metabolism*; D004781:Environmental Exposure; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D007371:Interferon-gamma / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008297:Male; D010126:Ozone / Q000009:adverse effects*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000378:metabolism*; D058408:Th1-Th2 Balance
D051858:Forkhead Transcription Factors; C500522:Foxp3 protein, rat; D012333:RNA, Messenger; D015847:Interleukin-4; D010126:Ozone; D007371:Interferon-gamma