Quercetin inhibits macrophage inflammatory response activated by TREM-1 and reduces LPS induced acute lung injury in mice / 中国医师杂志

ABSTRACT

Objective:To observe the therapeutic effect of quercetin (QUE) on triggering receptor expressed on myeloid cells (TREM-1) activated macrophage inflammation and lipopolysaccharide (LPS) induced acute lung injury (ALI) in mice, and explore its possible mechanism.Methods:In vitro cell experiment The primary peritoneal macrophages of mice were collected by intraperitoneal injection of 3% calcium mercaptan acetate. The collected cells were divided into blank control group, dimethylsulfoxide (DMSO) vehicle group, TREM-1 agonist group (10 μg/ml), QUE group (10 μmol/L) and TREM-1 agonist + QUE group (cells were pretreated with 10 μmol/L QUE for 30 min before adding agonist). Enzyme linked immunosorbent assay (ELISA) was used to detect the secretion of interleukin (IL)-1β, tumor necrosis factor (TNF)-α and IL-6 in the culture supernatant of primary macrophages; To observe the effect of QUE on LPS-induced TREM-1 protein levels, macrophages were divided into normal control group, LPS group (100 ng/ml) and LPS+ QUE treatment group [macrophages were pretreated with 10 μmol/L QUE for 2 hours, and then incubated with LPS (100 ng/ml) for 16 hours]. Western blot was used to detect the expression of TREM-1 protein. In animal experiments 80 male C57BL/6 mice were randomly divided into 4 groups (20 in each group) normal control group, ALI model group, QUE group and QUE treatment group (LPS+ QUE). In the ALI model group, the ALI model was established by intratracheal injection of 5 mg/kg LPS; The mouse ALI model was established by intratracheal injection of LPS 5 mg/kg in the QUE treatment group, and then intraperitoneal injection of 15 mg/kg QUE. The control group was given the same amount of normal saline intratracheal followed by intraperitoneal injection of DMSO, and the QUE group was given the same amount of normal saline intratracheal followed by intraperitoneal injection of 15 mg/kg QUE. Hematoxylin-eosin (HE) staining was used to observe the pathological changes of lung tissue in each group; Inflammatory cells including IL-1β, TNF- α and IL-6 in bronchoalveolar lavage fluid (BLAF) of mice in each group were counted ; The expression of TREM-1 mRNA and protein in lung tissue of mice in each group was detected by real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) and Western blot. Results:In vitro cell experiment the secretion of IL-1β, TNF-α and IL-6 in the supernatant of primary macrophages in TREM-1 agonist group was higher than those in DMSO vehicle group, while the secretion of IL-1β, TNF-αand IL-6 in the supernatant of primary macrophages in TREM-1 agonist + QUE group were lower than that of TREM-1 agonist group (all P<0.001). The expression of TREM-1 protein in LPS group was higher than that in control group ( P<0.05), while the expression of TREM-1 protein in LPS + QUE group was lower than that in LPS group ( P<0.05). Animal experiments showed that compared with the control group, the ALI model group had higher lung pathological injury score, more total cells, macrophages and neutrophils in BALF and increased TNF-α, IL-6, IL-1β content (all P<0.001). The above indexes in QUE group were lower than those in ALI model group (all P<0.001). The results of qRT-PCR and Western blot showed that compared with the control group, the expression of TREM-1 mRNA and protein in the lung tissue of ALI model group was increased, while the expression of TREM-1 mRNA and protein in the lung tissue of QUE group was lower than that of ALI model group (all P<0.05). Conclusions:Quercetin can inhibit TREM-1 activation, reduce macrophage inflammatory response and LPS induced acute lung injury in mice.