Curcumin affects ox‑LDL‑induced IL‑6, TNF‑α, MCP‑1 secretion and cholesterol efflux in THP‑1 cells by suppressing the TLR4/NF‑κB/miR33a signaling pathway
- Yi Zhong
- Cheng Liu
- Jian Feng
- Jia‑Fu Li
- Zhong‑Cai Fan
Affiliations: Department of Cardiology, Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China, Department of Cardiovascular Ultrasound and Cardiac Function, Sichuan Provincial People's Hospital, Chengdu, Sichuan 610000, P.R. China
- Published online on: June 19, 2020 https://doi.org/10.3892/etm.2020.8915
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The aim of the present study was to study the molecular mechanism of how curcumin decreases the formation of ox‑LDL induced human monocyte macrophage foam cells, promotes the efflux of cholesterol and reduces the secretion of inflammatory cytokines. In vitro cultured THP‑1 cells were induced to become macrophages using phorbol‑12‑myristate-13‑acetate. The cells were then pre‑treated with curcumin before inducing the foam cell model by addition of oxidized low‑density lipoprotein (ox‑LDL). Western blot assays were used to detect expression levels of toll‑like receptor (TLR)4, nuclear factor κB (NF‑κB), NF‑κB inhibitor α (IκBα), phosphorylated‑IκBα and ATP binding cassette transporter (ABC)A1. Reverse transcription‑quantitative PCR was employed to examine mRNA levels of TLR4, microRNA (miR)33a and ABCA1. ELISAs were used to detect inflammatory factors, including tumor necrosis factor (TNF)‑α, monocyte chemotactic protein (MCP)‑1 and interleukin (IL)‑6. ox‑LDL successfully induced the foam cell model, promoted phosphorylation of IκBα, promoted nuclear translocation of NF‑κB, promoted the expression of TLR4 and miR33a, and promoted the secretion of TNF‑α, MCP‑1 and Il‑6. Additionally, ox‑LDL reduced the expression of ABCA1 and cholesterol efflux. However, pretreatment with curcumin increased the expression of ABCA1 and cholesterol efflux and suppressed secretion of TNF‑α, MCP‑1 and Il‑6. TLR4 antibodies, the NF‑κB blocker, PDTC, and the miR33a inhibitor also reduced the abnormal transformations induced by ox‑LDL. Curcumin promoted cholesterol efflux by suppressing the TLR4/NF‑κB/miR33a signaling pathway, and reduced the formation of foam cells and the secretion of inflammatory factors.