The role of TLR4 receptor in the stress response of lymphocytes

: In vitro effects of low-level electromagnetic waves (8.18 GHz, frequency swings within 1 s, intensity 1 microW/cm, exposure for 1 h) and low-energy laser light (He-Ne laser with 632.8 nm, 0.2 mW/cm, dose 1.2 x 10(-2) J/cm2) on the expression of receptor protein TLR4, which is known as a part of the system for microbal toxin recognition, were studied in mouse lymphocytes. In addition, TLR4 expression was examined in situations when stress responses to low-level nonionizing radiation were modified by the antibiotic geldanamycin, which suppresses the activity of the heat shock protein Hsp90. It was found that low-level microwaves significantly raised the amount of TLR4; in contrast, laser light decreased the expression of the receptor in lymphocytes. In cells pretreated with geldanamycin, the TLR4 expression in irradiated cells was reduced to minimum levels, much lower than control values. The results showed that TLR4, which is involved in specific binding of toxin from gram-negative bacteria, can regulate cell responses to signals of other origin, in particular to nonionizig radiation, including low-level microwaves and laser light.