Celastrol Ameliorates Inflammation in Human Retinal Pigment Epithelial Cells by Suppressing NF-κB Signaling

• Published in: Journal of ocular pharmacology and therapeutics Vol. 35; no. 2; p. 116
• Main Authors: Zhang, Jingyue, Zhou, Kewen, Zhang, Xinyu, Zhou, Yeqi, Li, Zhen, Shang, Fu
• Format: Journal Article
• Language: English
• Published: United States 01.03.2019
• Subjects: Cells, Cultured; Humans; Inflammation - drug therapy; Inflammation - pathology; NF-kappa B - antagonists & inhibitors; NF-kappa B - metabolism; Ophthalmic Solutions - administration & dosage; Ophthalmic Solutions - pharmacology; Retinal Pigment Epithelium - drug effects; Retinal Pigment Epithelium - metabolism; Retinal Pigment Epithelium - pathology; Signal Transduction - drug effects; Triterpenes - administration & dosage; Triterpenes - pharmacology; NF-κB signaling; celastrol; retinal pigment epithelial cell; inflammation; age-related macular degeneration
• ISSN: 1557-7732
• DOI: 10.1089/jop.2018.0092

Celastrol is a triterpenoid quinine methide that exerts important biological effects on a variety of disease models. In this study, we aim to assess the ability of celastrol to inhibit lipopolysaccharide (LPS)-induced inflammation in retinal pigment epithelial (RPE) cells. Primary cultures of human RPE (HRPE) cells and ARPE-19 cell lines were treated with celastrol alone or in combination with LPS. The cytotoxic effect of celastrol on RPE cells was determined by the CCK-8 assay. Protein and mRNA levels of inflammatory cytokines, including IL-6, IL-8, and MCP-1, were detected by flow cytometry or by real-time fluorescent quantitative PCR, respectively. The levels of phosphorylated intermediates in the NF-κB signaling pathway (such as IκBα/β and p65) and MAPK signaling pathway (p38MAPK, SAPK/JNK, and p42/p44MAPK) were detected by western blotting. Celastrol significantly inhibited LPS-induced expression of protein and mRNA expression levels encoding the proinflammatory cytokines, IL-6, IL-8, and MCP-1, in both HRPE and ARPE-19 cells. Cell viability and apoptosis assays revealed that celastrol had no apparent cytotoxic effect and it inhibited apoptosis of RPE cells at concentrations of less than 1 μM. Mechanistically, RPE cells that were pretreated with celastrol exhibited a substantial decrease in phosphorylation of the NF-κB pathway regulators, IKKα/β and IκBα, and subsequently inactivated P65, suggesting that celastrol ameliorates LPS-induced inflammation by suppressing the NF-κB signaling pathway. Our results provide evidence that celastrol is a potent anti-inflammatory agent in RPE cells and it may have potential applications in prevention and treatment of age-related macular degeneration.