The effect of interleukin-10 on apoptosis in macrophages stimulated by oxLDL

Marked anti-atheromatous effects of the anti-inflammatory cytokine interleukin-10 (IL-10) were observed in several lipid-driven animal models of arteriosclerosis. We have previously demonstrated that IL-10 significantly inhibited lipid uptake in macrophages induced by oxLDL (Wang et al., 2008; Yang et al., 2008b). In this study, we investigated whether IL-10 affects the apoptosis related gene BCL2L11 and BMF expression in macrophages treated with oxLDL from THP-1 cells, which served as macrophage models. Cell apoptosis assays were performed by flow cytometry. Expression of the apoptosis related genes BCL2L11 and BMF mRNA was quantified by real-time RT-PCR (mRNA expression) and Western blotting (protein expression). IL-10 markedly blocked oxLDL induced cells undergoing early stage apoptosis. In the foam cell group, as compared with the macrophage group, the percentage of apoptosis increased by 100%. Here the expression of BCL2L11 was 45% (mRNA) and 41% (protein) elevated, while the expression of BMF was 54% (mRNA) and 44% (protein) elevated. When macrophages were co-stimulated by 100 mg/l oxLDL and 20 μg/l IL-10 for 24 h, compared with the foam cell group, the percentage of the apoptosis decreased by 21%, the expression of apoptosis related gene BMF was inhibited, the expression of mRNA and protein was both depressed by 23% and 20%, respectively, but the BCL2L11 expression was unchanged. These results may explain why decrement of early stage apoptosis cells was observed during co-stimulation and raise the possibility that IL-10 reduces foam cell undergoing apoptosis partly through down-regulating the expression of BMF, which demonstrates a critical role of IL-10 in anti-atherogenesis.