Hypertonic saline downregulate the production level of lipopolysaccharide-induced migration inhibitory factor in THP-1 cells

PURPOSE Macrophage migration inhibitory factor (MIF) may serve as a general marker for systemic inflammation in septic and nonseptic acute critical illness. Additionally, our previous experiment has demonstrated that immunosuppressant Prostaglandin E(2) (PGE(2)) lowered MIF levels and inhibited T-cells proliferation when compared to control levels. The addition of hypertonic saline (HTS) increased MIF production as compared with PGE(2)-stimulated T-cells in concordance with restore PGE(2)-suppressed T-cells proliferation. Generally, HTS has been well known for its anti-inflammatory effect so far. Therefore, the experiments were conducted to evaluate MIF after stimulating lipopolysaccharide (LPS) either in the presence or absence of HTS in monocyte, in response to early phase injury. METHODS Human acute monocytic leukemic cell line (THP-1) cells were cultured in RPMI media, to a final concentration of 1 × 10(6) cells/mL. The effect of HTS on LPS-induced MIF was evaluated in monocyte with 1 µg/mL LPS. HTS at 10, 20 or 40 mmol/L above isotonicity was added. MIF concentrations of the supernatant were determined by enzyme-linked immunosorbent assay, and cell lysates were used for Western blots analysis to determine the MIF expression. RESULTS MIF concentrations in the cell supernatant increased in LPS-induced cells compared to control cells. Also, levels of MIF protein expression were higher in LPS stimulating cells. However, the addition of HTS to LPS stimulated cell restored MIF concentrations and MIF expression. CONCLUSION The role of HTS in maintaining physiological balance in human beings, at least in part, should be mediated through the MIF pathway.