OBJECTIVETo investigate the protective effect of suppressive oligodeoxynucleotides (Sup ODN) on interferon-γ (IFN-γ) and signal transducers and activators of transcription (pSTAT4) expression of Silica-induced pulmonary inflammation in Mice.

METHODSSixty Balb/c mice were randomly divided into 4 groups, normal control group, silicious group, suppressive oligodeoxynucleotides (Sup ODN) group, control oligodeoxynucleotides (Con ODN) group. Except the normal control group injected normal saline, the rest groups were induced by the intratracheal instillation of 0.1 ml (5 g/L) of sterilized silica suspension. Sup ODN group and Con ODN group were treated by i.p. injection of 0.3 ml (1mg/mL) of suppressive or control ODN 3 h before silica administration. After 7 days, the animals were killed and levels of IFN-γ were detected by ELISA. The pathologic changes in lung tissues of mice were observed with HE staining. Expressions of IFN-γ and pSTAT4 in lung tissue were detected with immunohistochemistry and quantified by Image-Pro Plus 7.0.

RESULTSHE staining showed that the lung tissue of silicious group were damaged seriously than Sup ODN group. Compared with the normal control group (serum: (280.1±41.3) pg/ml, lung tissue: (0.249±0.373), IFN-γ increased in silicious group (serum: (886.3±81.7) pg/ml, lung tissue: (0.270±0.300) (P < 0.05). Compared with the normal control group and Con ODN group [(894.5±91.6) pg/ml], IFN-γ in the serum of Sup ODN group decreased significantly (P < 0.01). Compared with the silicious group , IFN-γ in lung tissue decreased in Sup ODN group (0.241±0.250) (P < 0.05). Compared with the normal control group (0.279±0.353), pSTAT4 in lung tissue increased significantly in silicious group (0.313±0.231) (P < 0.01). Compared with the silicious group, pSTAT4 in lung tissue decreased significantly in Sup ODN group (0.269±0.523) (P < 0.01).

CONCLUSIONSup ODN attained protective effect on Silica treated mice by suppressing expression of IFN-γ and pSTAT4.