Roxithromycin inhibits nuclear factor kappaB signaling and endoplasmic reticulum stress in intestinal epithelial cells and ameliorates experimental colitis in mice

Abstract

Roxithromycin is known to have anti-inflammatory and immunoregulatory activity. However, little information is available on the effect of roxithromycin in intestinal inflammation. The aim of this study was to investigate the effect of roxithromycin on NF– κB signaling and ER stress in intestinal epithelial cells (IECs) and the effect of roxithromycin on dextran sulfate sodium (DSS)-induced acute colitis in a murine model. HCT116 cells and COLO205 cells were pretreated with roxithromycin and then stimulated with tumor necrosis factor-α (TNF-α). Interleukin (IL)-8 expression was determined by real-time reverse transcription–polymerase chain reaction. Nuclear factor kappaB (NF-κB) DNA-binding activity and IκB phosphorylation/degradation were evaluated by electrophoretic mobility shift assay and Western blot analysis. The molecular markers of endoplasmic reticulum stress, including p-JNK, phosphorylated eukaryotic initiation factor 2 (p-eIF2α), C/EBP homologous protein (CHOP), and X-box binding protein 1 (XBP1) were evaluated using western blotting and PCR. Mice were given 4% DSS for five days with or without roxithromycin. Primary IECs were isolated from mice with DSS-induced colitis. Roxithromycin significantly inhibited the upregulated expression of IL-8. Pretreatment with roxithromycin markedly attenuated NF-κB DNA-binding activity and IκB phosphorylation/degradation. CHOP and XBP1 mRNA expression were enhanced in the presence of TNF-α, and it was dampened by pretreatment of roxithromycin. c-Jun-N-terminal kinase (JNK) phosphorylation and the level of p-eIF2α were also downregulated by the pretreatment of roxithromycin. Roxithromycin significantly reduced the severity of DSS-induced murine colitis, as assessed by the disease activity index, colon length, and histology. In addition, the DSS-induced phospho-IκB kinase activation was significantly decreased in roxithromycin-pretreated mice. Finally, IκB degradation was reduced in primary IECs from mice treated with roxithromycin. These results suggest that roxithromycin may have potential usefulness in the treatment of inflammatory bowel disease.