High-salt diet inhibits maturation and killing function of NK cells in mice

Abstract

Objective To investigate the effects of high-salt diet on the maturation and function of NK cells. Methods Mouse models of normal salt diet (NSD) and high salt diet (HSD) were established by feeding food and drinking water with different salt content. The expression of CD27 and CD11b was used to define the NK cell maturation subsets, and the early activation of cells was labeled by CD69. Flow cytometry was employed to analyze the distribution of NK cell subsets and activation in NSD and HSD mice. The IFN-γ production level of NK cells from mice treated with polyI: C for 18 h in vivo and stimulated with PMA/Ionomycin for 4 h in vitro was detected by flow cytometry. Cytotoxic activity of NK cells was determined through the YAC-1 killing experiment in vivo. Results HSD showed no effect on the percentage of NK cells in the liver, spleen, bone marrow and peripheral blood, but inhibited the expression of CD69 in liver and spleen NK cells (P < 0.01). The percentage of immature NK cells (CD27+CD11b-) subsets was significantly higher in the liver, spleen and bone marrow from HSD mice when compared to those in NSD mice (P < 0.05), while the percentage of mature M1 NK cell subsets (CD27+CD11b+) as well as DX5+NK1.1+ mature NK cells were markedly lower in HSD mice (P < 0.05), suggesting that HSD inhibits the maturation of NK cells. The expression of IFN-γ in NK cells of HSD mice was lower than that of NSD mice (P < 0.01), indicating that HSD inhibited NK cell function. Moreover, YAC-1 in vivo killing experiment showed that the percentage and absolute number of residual YAC-1 cells in the abdominal cavity of HSD mice were higher than those of NSD mice (P < 0.01), indicating that HSD inhibited the cytotoxicity of NK cells. Conclusion HSD inhibits the maturation of NK cells as well as the activation and function of NK cells.

Keywords

• high-salt diet
• nk cells
• cd27
• cd11b
• ifn-γ
• yac-1 cells