Enhanced benzene-induced DNA damage in PMA-stimulated cells in vitro and in LPS-treated animals

The present study investigated the interaction between inflammatory reactio ns and benzene in vitro and in vivo with respect to oxidative DNA damage. I n the in vitro models the oxidative burst of cells was induced by the pretr eatment with phorbol myristate acetate (PMA) and in the in vivo models of i nflammation mice were pretreated with lipopolysaccharide (LPS). The oxidati ve DNA damage was indicated by 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG ) and strand breaks as assessed by alkaline single cell gel electrophoresis (SCGE, Comet assay). The results showed that combination of PMA and benzen e enhanced the level of 8-oxodG in DNA from mouse bone marrow cells by 197% , from human lymphocytes by 188% and from human neutrophils by 205% (p < .0 5). Pretreatment of mice with LPS and benzene resulted in an enhanced Comet score formation in bone marrow cells by 98% and in lymphocytes by 39% in C omet score (p < .05) and in an enhanced 8-oxodG level in bone marrow cells by 290%. The effects of the combined treatment with PMA/LPS and benzene exc eeded the sum of the effects induced by PMA/LPS or benzene alone. The produ ction of nitrate/nitrite showed a two fold increase in the supernatant from incubation of benzene and PMA-pretreated neutrophils. The increase in the 8-oxodG level in the human neutrophil incubation system demonstrated a corr elation with nitrate/nitrite production, indicating a possible relationship with the generation of reactive nitrogen species. (C) 1999 Elsevier Scienc e Inc.