The inhibitory effect of quercetin on IL-6 production by LPS-stimulated neutrophils.
Quercetin is a herbal flavonoid derived from various foods of plant origin and plays a role in anti-inflammation. Although a number of researches in the field have been done, the mechanism of anti-inflammatory effect of quercetin should be further clarified. In the present study, we investigated the effects of quercetin on IL-6 production by LPS-stimulated neutrophils in human. Neutrophils were were pre-treated with quercetin at the final concentrations of ranging from 0-80 microM for 30 min, or not treated, and then incubated in the presence or absence of lipopolysaccharide (LPS) at a final concentration of 100 ng/ml for indicated time. The secretion level of IL-6 in the culture supernatants was assayed by ELISA, the intracellular level of IL-6 was detected by flow cytometry and the expression of IL-6 mRNA was analyzed by RT-PCR. The experiment results showed that neutrophils cultured with medium or quercetin alone did not express IL-6, but LPS (100 ng/ml) induced IL-6 expression of neutrophils. However, after pre-treatment of neutrophils with quercetin (40 microM) for 30 min, the inducible effects of LPS on the increase of IL-6 secretion, intracellular IL-6 level and IL-6 mRNA expression by neutrophils were abrogated. IL-6 is one of the important pro-inflammatory factors, especially in early phage of inflammation. Thus, our data suggested that quercetin might exert its anti-inflammatory effect through negatively modulating pro-inflammatory factors, such as IL-6. The inhibitory effects of quercetin on IL-6 production by neutrophils may provide a theoretical basis on future therapy of inflammation.
Liu
Jiajia
J
Laboratory of Molecular Biology, Luzhou Medical College, Luzhou 646000, Sichuan, China.
Li
Xin
X
Yue
Yang
Y
Li
Juan
J
He
Tao
T
He
Yanzheng
Y
D002478:Cells, Cultured; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D015394:Molecular Structure; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism*; D011794:Quercetin / Q000737:chemistry / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics
D015850:Interleukin-6; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011794:Quercetin