Figure 4 From: Tumor necrosis factor alpha and adalimumab differentially regulate CD36 expression in human monocytes Mechanisms involved in the regulation of CD36 expression by adalimumab. (a) The increase in CD36 membrane expression induced by adalimumab is not inhibited by a peroxisome proliferator-activated receptor (PPAR)γ antagonist (GW9662). Monocytes were incubated with macrophage-serum-free medium (M-SFM) alone (control), or with M-SFM containing either adalimumab (Ada; 1 μg/ml), GW9662 (GW; 2 μM), or adalimumab combined with GW9662 for 24 h, and the membrane expression of CD36 was quantified using flow cytometry. Data represent the geometric mean ± standard error (SE) of the fluorescence measured in three experiments in duplicate. *Significantly different from the control (p < 0.05). (b) Adalimumab induces ROS production. Monocytes were incubated with Hanks balanced salt solution (HBSS) alone (control), or with HBSS containing adalimumab (Ada; 1 μg/ml) for 1 h. Reactive oxygen species production was measured by chemiluminescence in the presence of 5-amino-2,3-dihydro-1,4-phthalazinedione in a thermostatically controlled luminometer. Data represent total chemiluminescence emission (area under the curve) for 1 h, measured in three experiments. *Significantly different from the control (p < 0.05). (c) The increase in CD36 membrane expression induced by adalimumab is inhibited by an anti-oxidant (Trolox). Monocytes were incubated with M-SFM alone (control), or with M-SFM containing either adalimumab (Ada; 1 μg/ml), Trolox® (1 μM), or adalimumab combined with Trolox® for 24 h and the membrane expression of CD36 was quantified using flow cytometry. Data represent the geometric mean ± SE of the fluorescence measured in three experiments in duplicate. *Significantly different from the control (p < 0.05). (d) The increase in CD36 membrane expression induced by adalimumab is inhibited by a NADPH inhibitor (diphenylene iodonium chloride (DPI)). Monocytes were incubated with M-SFM alone (control), or with M-SFM containing either adalimumab (Ada; 1 μg/ml), DPI (1 μM), or adalimumab combined with DPI for 24 h and the membrane expression of CD36 was quantified using flow cytometry. Data represent the geometric mean ± SE of the fluorescence measured in three experiments in duplicate. *Significantly different from the control (p < 0.05).Back to article page