OBJECTIVETo investigate the effect of hydrogen dioxide (H(2)O(2)) on the release and translocation of high mobility group box 1 release (HMGB1) from normal human bronchiolar epithelial cells (HBE).

METHODSMTT assay was used to assess the viability of HBE135-E6E7 cells exposed to different concentrations of H(2)O(2). The expression and location of HMGB1 in the cytoplasm, nuclei and culture medium of the exposed cells were determined using Western blotting and immunofluorescence assay.

RESULTSExposure to 125 µmmol/L H(2)O(2) did not obviously affect the cell viability. At the concentration of 250 µmmol/L, H(2)O(2) significantly decreased the cell viability (P<0.05), but significant cell death occurred only after exposure to 400 µmmol/L H(2)O(2) (P=0.000). Compared with the control cells, the cells exposed to 12.5, 125 and 250 µmmol/L H(2)O(2) for 24 h showed significantly increased levels of HMGB1 in the culture medium (P<0.05), and exposure to 125 µmmol/L H(2)O(2) for 12 and 24 h also caused significantly increased HMGB1 level (P<0.05). Exposure to 125 µmmol/L H(2)O(2) for 24 h significantly increased HMGB1 expression in the cytoplasm but decreased its expression in the nucleus. HMGB1 translocation from the nuclei to the cytoplasm and to the plasmalemma occurred after 125 µmmol/L H(2)O(2) exposure for 12 h and 24 h, respectively.

CONCLUSIONH(2)O(2) can induce HMGB1 translocation and release in human bronchial epithelial cells, suggesting the involvement of HMGB1 in airway oxidative stress in chronic inflammatory diseases such as asthma and COPD.