Inhibition effect of recombinant human brain natriuretic peptide in oxidised low-density-liporotein induced oxidative stress and inflammatory respones of macrophages

Objective To investigate the inhibition effect of recombinant human brain natriuretic peptide (rhBNP) in regulating oxidised low density lipoprotein (ox-LDL) induced oxidative stress and inflammatory responses in macrophage. Methods A model of ox-LDL-induced macrophage injury was established to evaluate the effect of rhBNP and divided into 3 groups: control group, 100 μg/ml ox-LDL group, 100 μg/ml ox-LDL+ 10-9 mol/L rhBNP group. Confocal microscopy was used to determine the cellular reactive oxygen species (ROS) levels. Reverse transcription polymerase chain reaction (RT-PCR) and colourimetry were used to detect the mRNA expression and activity, respectively, of superoxide dismutase (SOD) and malonaldehyde (MDA). Additionally, use enzyme-linked immunosorbent method (ELISA) to measure the IL-37 levels in cell culture medium of each group. Results Compared with the control group, intracellular ROS levels increased (527.30%±36.20% vs. 100.00%±0.00%), SOD mRNA expression and activity decreased [0.53±0.18 vs. 1.00±0.00, (256.60±8.20)U/ml vs. (355.80±9.58)U/ml], MDA mRNA expression and content increased [1.59±0.23 vs. 1.00±0.00, (29.40±1.68)nmol/ml vs. (5.94±0.51)nmol/ml], the level of IL-37 decreased [(48.05±3.01)ng/L vs. (57.82±2.26)ng/L] in the 100 μg/ml ox-LDL group (all P<0.05); these effects were significantly counteracted by 10-9 mol/L rhBNP [237.30%±30.62%, 0.90±0.07, (310.40±2.97)U/ml, 1.14±0.10, (20.54±1.55)nmol/ml, (53.06±1.87)ng/L, all P<0.05]. Conclusions rhBNP may up-regulate IL-37 levels by increasing SOD expression and activity, and inhibit ox-LDL-induced macrophage oxidative stress and inflammatory. Key words: Recombinant human brain natriuretic peptide; THP-1 macrophages; Oxidized low-density lipoprotein; Superoxide dismutase; Malondialdehyde; Interleukin-37