BACKGROUND Selective blocking of HDAC6 has become a promising strategy in treating inflammatory bowel disease. CKD-506 is a novel isoform-selective inhibitor of histone deacetylase 6. The present study was performed to evaluate the effect of CKD-506 on the NF-κB signaling pathway in intestinal epithelial cells (IECs) and macrophages and on murine models of acute and chronic colitis.

METHODS RAW264RAW264.7 murine macrophages and COLO 205 human IECs were pretreated with CKD-506 and then stimulated with lipopolysaccharides (LPS). Cytokine expression of TNF-α, interleukin (IL)-6, IL-8, and IL-10 was measured by ELISA. The effect of CKD-506 on NF-κB signaling was evaluated by Western blotting of IκBα phosphorylation/degradation and electrophoretic mobility shift assay. In vivo studies were performed using a dextran sulfate sodium (DSS)-induced acute colitis model, a chronic colitis model in IL-10 knockout mice, and an adoptive transfer model. Colitis was quantified by the disease activity index, colon length, and histopathologic evaluation.

RESULTS CKD-506 suppressed the expression of pro-inflammatory cytokines such as IL-6, IL-8, and TNF-α in IECs and macrophages. CKD-506 strongly inhibited IκBα phosphorylation/degradation and the DNA-binding activity of NF-κB. Oral administration of CKD-506 attenuated DSS-induced acute colitis and chronic colitis in IL-10-/- and adoptive transfer models. CKD-506 ameliorated weight loss, disease activity, and histopathologic score in colitis mice and downregulated IκBα phosphorylation and pro-inflammatory cytokine production significantly.

CONCLUSIONS CKD-506 blocked NF-κB signaling in IECs and macrophages and ameliorated experimental acute and chronic murine colitis models, which suggests that CKD-506 is a promising candidate for inflammatory bowel disease treatment as a small molecular medicine.