A static magnetic field reduces lipopolysaccharide-induced proinflammatory cytokine levels of fibroblasts by altering membrane fluidity

Lipopolysaccharide (LPS) is one of the major substances that initiate an immune host response in microbial infections which results in cytotoxicity. In terms of the treatment of the immune response, much research on endotoxin tolerance that can reduce LPS-induced damages has been conducted. In this experiment, cultured fibroblasts were challenged with LPS in order to initiate an inflammatory reaction. Cell numbers and various proinflammatory cytokine levels were compared between a static magnetic field (SMF)-exposed group and an unexposed group. Our results showed that with LPS challenge, fibroblasts exposed to a 4000-G SMF demonstrated a higher cell density (8.28 +/- 0.14 10(4) cells/ml) when compared to the unexposed (control) group (4.5 +/- 0.16 10(4) cells/ml, p < 0.05). Meanwhile, levels of LPS-induced interleukin-1 beta and tumor necrosis factor-alpha in the SMF-exposed groups were significantly lower at 32.9% and 61.4% than those of the unexposed counterparts, respectively (p < 0.05). The change in the fluorescence anisotropy of TMA-DPH increased when cells were exposed to SMF. These results indicate that a static magnetic field may decrease LPS-induced proinflammatory cytokine levels by altering the membrane fluidity.