Figure 6.

MIP-1α expression by palmitate and/or TNF-α, in presence or absence of oxidative stress. To test whether the oxidative stress was induced by palmitate and/or TNF-α, THP-1 cells were treated with H₂O₂ (10 mM for 10 h), palmitate, TNF-α, as well as palmitate+TNF-α and the intracellular expression of reactive oxygen species (ROS) was measured by DCFH-DA assay as described in Section Materials and Methods. The representative flow cytometry data obtained from three independent determinations with similar results show the increased ROS expression in THP-1 cells treated with (A) H₂O₂ (SI = 23.10), (B) palmitate (SI = 5.89), (C) TNF-α (SI = 2.73), and (D) palmitate+TNF-α (SI = 33.86), indicating induction of the oxidative stress by all treatments. (E) ROS induction by H₂O₂ was higher (P = 0.002) than that induced by palmitate or TNF-α, but lower (P = 0.008) than that co-induced by palmitate and TNF-α. Next, THP-1 cells were treated with vehicle (control); palmitate; TNF-α; and palmitate+TNF-α, in the presence or absence of H₂O₂. The representative data (mean ± SEM) obtained from three independent determinations with similar results show the upregulated expression of (F) MIP-1α transcripts and (G) MIP-1α secreted protein in the presence of H₂O₂ (All P < 0.05); except the MIP-1α gene expression co-induced by palmitate and TNF-α, with or without H₂O₂ (P = 0.98). MFI: mean fluorescence intensity; SI: staining index. ** denotes P-value < 0.01.