Abstract:

Objective To investigate the effects of curcumin on mRNA expression of cytokines related to Toll-like receptor （TLR） 4 signaling in THP-1 cells. Methods After pretreatment with different concentrations （50, 25, 12.5 mg/L） of curcumin or dexamethasone for 12 hours, THP-1 cells were stimulated by lipopolysaccharide （LPS, 1 mg/L） for 4 hours followed by the collection of cells. Then total RNA was isolated from these cells and subjected to reverse transcription-polymerase chain reaction （RT-PCR） for the detection of mRNA expression of tumor necrosis factor receptor-associated factor 6 （TRAF6）, interleukin-1 receptor-associated kinase （IRAK1） and nuclear factor （NF）-κB. THP-1 cells without pretreatment or stimulation served as negative control, and those only stimulated with LPS served as LPS group. Results After stimulation with LPS （1 mg/L） for 4 hours, the mRNA expressions of TRAF6, IRAK1 and NF-κB were significantly upregulated in THP-1 cells compared with negative control cells （t = 38.69, 39.13, 23.99, all P < 0.01）. Curcumin of 50 mg/L and 25 mg/L significantly inhibited the mRNA expressions of TRAF6, IRAK1 and NF-κB upregulated by LPS with an inhibition rate of more than 50% （all P < 0.01）. Conclusions Certain concentrations of curcumin can inhibit the mRNA expressions of TRAF6, IRAK1 and NF-κB，which demonstrates the regulatory effect of curcumin on the mRNA expressions of TLR4 signaling pathway-associated cytokines.

Key words: Curcumin, TNF receptor-associated factor 6, Interleukin-1 receptor-associated kinases, NF-kappa B, Cell line