Effects of high glucose and lysophosphatidylcholine (LPC) on RAW264.7 macrophages during Nocardia farcinica infection

Abstract

Objective To investigate the effects of high glucose and lysophosphatidylcholine (LPC) on the immune function of in vitro cultured macrophages during Nocardia farcinica infection. Methods RAW264.7 macrophages were cultured in vitro under different conditions as follows: routine culture (control group), 50 mmol/L glucose (high glucose group), 10 mg/L LPC (LPC groupⅠ), 25 mg/L LPC (LPC groupⅡ) and 50 mmol/L glucose+ 25 mg/L LPC (high glucose and LPC group). The activity of macrophages in each group was tested after 6, 12, 24 and 36 h of culture. After 24 h of culture, macrophages were collected from every group and co-cultured with Nocardia farcinica. Dynamic phagocytosis rates were detected at 1, 2, 3, 4, 5 and 6 h after co-culture. Toxic effects of Nocardia farcinica on macrophages and concentrations of IL-10 and TNF-α were measured at 1, 3 and 6 h after co-culture. Results Macrophages in all four experimental groups showed decreased activity as compared with those in the control group (P<0.01). Phagocytosis of Nocardia farcinica by macrophages was also reduced by high glucose and LPC. Phagocytosis rates of high glucose group and LPC groupⅡ at 1 and 2 h, LPC groupⅠat 1, 2 and 3 h, and high glucose and LPC group at 1, 2, 3 and 4 h after co-culture were significantly lower than that of the control group (P<0.05 or P<0.01). Compared with the control group, significantly reduced toxic effects on macrophages caused by Nocardia farcinica was observed in the experimental groups (P<0.05 or P<0.01). Compared with the control group, LPC groupsⅠand Ⅱ and high glucose and LPC group had decreased secretion of IL-10 at 3 h, and high glucose group and LPC groupⅠhad decreased secretion of TNF-α at 1 h (P<0.05). Conclusion Culture macrophages under the conditions of high glucose and LPC would reduce their activity and impair their ability to phagocytose Nocardia farcinica. Moreover, high glucose and LPC might have impacts on the toxic effects of Nocardia farcinica on macrophages and the secretion of IL-10 and TNF-α. Key words: Nocardia farcinica; RAW264.7 macrophage; High glucose; Lysophosphatidylcholine; Phagocytosis