Effect Of Berberine On Pro-inflammatory Cytokine Production By ARPE-19Cells Following Stimulation With TNF-α

Purpose: Berberine (BBR) is a well known drug used in traditionalmedicine and has been shown to possess anti-inflammatory properties.Whether it can affect the production of inflammatory cytokines by retinalpigment epithelial (RPE) cells is not yet clear and was therefore the subjectof our study.Methods: ARPE-19cells were cultured with TNF-α in the presence orabsence of BBR for different time points.Concentrations of IL-6, IL-8andMCP-1in the supernatant were measured using an enzyme-linkedimmunesorbent assay (ELISA). mRNAexpression of these cytokines wasmeasured by real-time polymerase chain reaction (real-time PCR).Phosphorylation of p38mitogen-activated protein kinase (MAPK),extracellular signal-regulated kinase (ERK1/2) and c-Jun N-terminalkinases (JNK) was measured by western-blot.Thesignal transductionmechanisms involved in cytokine production were evaluated using variousinhibitors respectively for p38, ERK1/2and JNK.Results: TNF-α significantly increased the expression of IL-6, IL-8 and MCP-1in ARPE-19cells at both the protein and mRNA levels. Itpromoted the phosporylation of p38, ERK1/2and JNK. Inhibitoryexperiments showed that IL-6was modulated by p38whereas IL-8andMCP-1were modulated by p38, ERK1/2and JNK signal pathways. BBRremarkablyinhibited the expression of IL-6, IL-8and MCP-1at bothprotein and mRNA levels and down-regulated the phoshorylation of p38,ERK1/2and JNK upon stimulation with TNF-α.Conclusion:The present results suggested that BBR significantlyinhibits the expression of inflammatory cytokines in ARPE-19cells andthat the inhibitory effect is mediated by down-regulating p38, ERK1/2andJNK pathways.