Effects of macrophages depletion on lipopolysaccharide-induced renal and extra-renal inflammatory response in mice

Objective: To study the effect of macrophages depletion through selective colony-stimulating factor 1(CSF 1) receptor inhibitor GW2580 on inflammatory response induced by lipopolysaccharide(LPS) in mice. Methods: Nine male mice were divided equally into three groups and sacrificed on the 0th, 4th and 7th day after administration of GW2580 (160 mg/kg), respectively. The single cell suspension of spleen were prepared and subjected to flow cytometry assay, the percentage of macrophages in spleen cells at each time point was measured and the depletion efficiency of GW2580 on macrophages was evaluated. Another 9 mice were divided into normal control group, LPS group and GW2580+LPS group with 3 mice in each group. The normal control group were sacrificed without any treatment, the mice in LPS group were sacrificed 16 hours after intraperitoneal injection of LPS, and the mice in GW2580+LPS group were injected with LPS intraperitoneally after administration of GW2580 intragastrically for 1 week and sacrificed 16 hours later. Enzyme linked immunosorbent assay (ELISA) was used to determine the level of tumor necrosis factor-alpha (TNF-α) expression in serum of mice. The creatinine in blood and urinary protein were measured and the histological changes of kidney tissue were compared among the 3 groups. Results: The GW2580 significantly reduce the number of macrophages in the spleen of mice, and the percentages of macrophages in total spleen cells were 7.42%, 4.78% and 3.50% on 0 th, 4 th and 7 th day (P<0.05) after GW2580 administration. LPS raised the level of TNF-α in LPS group (126.4±16.47 pg/mL) (1 pg/mL=1 ng/L) significantly, while the GW2580+LPS and normal control group were below the detection limit of 31.3 pg/mL(P<0.05). Compared with LPS group, GW2580+LPS group had lower level of TNF-α and less renal pathological injury with less inflammatory cells infiltration and alleviated vacuolar degeneration of kidney tubules. Conclusions: GW2580 could reduce the level of the TNF-α by depleting macrophages, alleviating renal injury caused by LPS -induced inflammation