ABSTRACT
Objective:To investigate the regulatory effect of WNT1-inducible signaling pathway protein 2(WISP2)on macrophage polarization in palmitic acid(PA)and lipopolysaccharide(LPS)-induced inflammation.Methods:The macrophage cell line RAW264.7 was treated with different concentrations of WISP2 protein, and cell viability was determined by means of luminescence assay using Cell-Titer Glo to determine the concentration of WISP2.The cells were divided into control group, palmitic acid group, palmitic acid combined with different concentrations of WISP2 group(10 μg/L and 100 μg/L)and lipopolysaccharide group, lipopolysaccharide combined with different concentrations of WISP2 group(10 μg/L and 100 μg/L). mRNA expression of M1 and M2 macrophages phenotype of each group were detected by real-time quantitative polymerase chain reaction.The protein expression of important inflammatory factors, TNF-α and IL-6, were evaluated by ELISA.Results:Compared with the control group, both 10 μg/L and 100 μg/L WISP2 groups had no effect on the activity of RAW264.7 cells, but significantly up-regulated the expression of various inflammatory factors, including Tnfα(1.877±0.039, 2.202±0.034, F=309.7, P<0.001), Il6(1.418±0.056, 1.506±0.059, F=81.39, P<0.001), Mcp1(1.620±0.014, 1.982±0.125, F=71.45, P<0.001), Ccl3(1.892±0.118, 1.942±0.132, F=32.93, P<0.001), and iNos(1.691±0.201, 1.548±0.090, F=13.60, P<0.05). mRNA in macrophages, and significantly down-regulated the expression of anti-inflammatory factors, including Tgfβ(1.376±0.025, 2.152±0.107, F=1.846, P<0.05), CD206(2.123±0.031, 3.139±1.663, F=8.037, P<0.05), Il4(2.098±0.464, 2.494±0.141, F=48.68, P<0.01), and Il10(1.303±0.216, 1.574±0.274, F=5.774, P<0.05)mRNA, causing M1 type macrophage polarization.Compared with the control group, 100 μmol/L palmitic acid could mildly but significantly increase the expression of inflammatory factors such as TNF-α and IL-6 at the transcriptional and protein levels.Compared with palmitic acid stimulation alone, the combination of palmitic acid and WISP2 further promoted the protein expression of macrophage inflammatory factors TNF-α[(589.4±17.0)ng/L, (692.6±83.4)ng/L, F=56.38, P<0.05], IL-6[(15.13±1.14)ng/L, (13.33±1.22)ng/L, F=23.32, P<0.001]and the mRNA expression of chemokines Mcp1(160±9.796, 140±18.91, F=141.1, P<0.0001)and C cl3(17.76±1.92, 14.41±1.27, F=125.2, P<0.0001). Compared with the control group, 100 μg/L lipopolysaccharide strongly stimulated the expression of inflammatory factors such as TNF-α[(3444±423)ng/L, F=71.20, P<0.0001]and IL-6[(497.0±41.2)ng/L, F=63.50, P<0.0001]in macrophages at the protein level.Compared with lipopolysaccharide stimulation alone, the combination of lipopolysaccharide and WISP2 further significantly up-regulated the mRNA expression of chemokines Mcp1(106.8±8.7, 118.7±4.6, F=251.5, P<0.0001)and Ccl3(35.3±12.5, 116.4±4.5, F=160.1, P<0.0001). Conclusions:The adipokine WISP2 can promote M1 macrophage polarization in palmitic acid and lipopolysaccharide-induced inflammation, and it had distinct regulation in macrophage polarization under different inflammatory response conditions.