Skip to main content
Figure 4 | Arthritis Research & Therapy

Figure 4

From: Tumor necrosis factor alpha and adalimumab differentially regulate CD36 expression in human monocytes

Figure 4

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