Fig. 1

HDAC6 inhibitors suppress HDAC6-induced inflammatory responses. a, b Primary peritoneal macrophages (n = 3) were pretreated for 1 h with the indicated concentrations with CKD-506 or tubastatin (TBA) and then transfected with a control (pcDNA3.1 [pc]) or HDAC6 expression vector (1 μg/ml). At 48 h post-transfection, the levels of TNF-α (a) and IL-6 (b) in the culture medium were measured by ELISA. c, d RAW 264.7 cells (n = 3) were pretreated for 1 h with CKD-506 and then transiently co-transfected with an NF-κB (c) or AP-1 (d) promoter-luciferase expression vector, a β-galactosidase plasmid (pCMV-lacZ), and a control or HDAC6 expression vector. After 48 h, the luciferase activity in transfected cells was determined. Luciferase activity was normalized to that of β-galactosidase and expressed as -fold change over the control level. Data are expressed as the mean ± SEM of three independent experiments. *p < 0.05, **p < 0.01, and ***p < 0.001, compared with HDAC6-transfected cells. e, f PBMCs from RA patients (n = 5) were pretreated for 1 h with increasing concentrations of CKD-506 and then stimulated with LPS (100 ng/ml). Production TNF-α and IL-6 in the supernatant was measured using an ELISA. All data represent the mean value ± SEM. *p < 0.05, **p < 0.01 compared with no CKD-506 treatment. pc, plasmid control; TNF, tumor necrosis factor; IL, interleukin; TBA, tubastatin