Signal transduction mechanism of Chlamydia pneumoniae in down-regulating the expression of ABCA1 and ABCG1 from THP-1-derived macrophages / 中国病理生理杂志

ABSTRACT

AIM: To investigate the signal transduction mechanism of Chlamydia pneumoniae (Cpn) in down-regulating the expression of ATP binding cassette A1 (ABCA1) and ATP binding cassette G1 (ABCG1),the key molecules in cholesterol efflux and atherogenesis,from THP-1-derived macrophages. METHODS: Cpn was propagated in Hep-2 cells. THP-1 monocytes were induced into macrophages by 160 nmol/L phorbol myristate acetate (PMA) for 48 h,and were randomly allocated into 4 groups to incubate continually control group,50 mg/L low density lipoprotein (LDL); Cpn infection group,Cpn (1×10~6 IFU) and 50 mg/L LDL; Cpn and SP600125 (a special JNK inhibiter) group,THP-1 macrophages were previously treated with different concentrations (1-20 μmol/L) of SP600125 for 1 h,and then infected with Cpn (1×10~6 IFU) and 50 mg/L LDL; SP600125 group,SP600125(20 μmol/L)and 50 mg/L LDL. The expressions of ABCA1/ABCG1 and peroxisome proliferator-activated receptor γ (PPARγ) from each group were detected then. The cholesterol efflux was detected by enzyme-fluorescence. The expressions of ABCA1/ABCG1 and PPARγ mRNA and protein were determined by RT-PCR and Western blotting,respectively. RESULTS: Cpn not only down-regulated the ABCA1/ABCG1 expression,but also down-regulated the expression of PPARγ,which regulated the ABCA1/ABCG1 genes transcriptions. However,the mentioned effects of Cpn infection were restrained by the special JNK inhibitor SP600125 in a dose-dependent manner. CONCLUSION: Chlamydia pneumoniae may down-regulate ABCA1/ABCG1 expression from THP-1-derived macrophages via JNK-PPARγ signal transduction pathway.