Pulmonary drug-metabolizing enzyme in alveolar macrophages in relation to cigarette smoking

Presence of phenol UDP-glucuronosyltransferase in bovine alveolar macrophages and bronchial epithelial cells

Pulmonary organ and cells are the primary target of atmospheric pollutants. Phenol UDP-glucuronosyltransferase (UGT) was found in bovine alveolar macrophage cells by immunohistochemical staining and also was observed in bronchial epithelial cells of the lung. A high level of activity of UGT, which is one of the phase II drug-metabolizing enzymes, toward 1-naphthol was observed in the microsomes of both cell types. By Western blotting analysis, a 54-kDa band was detected in alveolar macrophage cells and in bovine lung using polyclonal antibodies against a purified rat UGT, which catalyze the glucuronidation of various phenolic xenobiotics such as 1-naphthol and have the same molecular mass (54 kDa). Reverse transcriptase-polymerase chain reaction (RT-PCR) amplified the common cDNA region in UGT1A subfamily isoforms, indicating that UGT1A subfamily isoform was expressed in alveolar macrophages and in bronchial epithelial cells of the lung. These results suggest that phenol UGT act as a primary barrier against various phenolic chemicals in the lung.

Cigarette smoking protects mononuclear blood cells of carcinogen exposed workers from additional work exposure-induced DNA single strand breaks

DNA single-strand breaks in mononuclear blood cells (MNC) of taxi drivers, painters, ethylene oxide-exposed sterilization workers, metal workers, and car mechanics were detected by alkaline filter elution and compared to smoking and non-smoking control persons. Cigarette smoking caused a small but statistically significant increase in control persons (13.5%). In all occupationally exposed groups except the car mechanics, statistically significant increases of DNA single-strand breaks were detected in non-smokers compared to non-smoking controls or comparing groups with high and low exposure. For non-smoking workers the increase in DNA single-strand breaks was found to be 22% for taxi drivers, 60% for painters, 70% for ethylene oxide-exposed workers, and 69% for metal workers compared to control persons. For smokers, however, the increase in DNA single-strand breaks caused by additional occupational exposure was smaller and did not reach statistical significance in any of the occupational groups investigated in this study. Since a high level of glutathione may help to detoxify electrophilic DNA-damaging agents we measured the concentration of total glutathione in MNC of smoking and non-smoking control persons. The glutathione concentration was 13% higher in smokers, but statistical significance was weak (p < 0.05; t-test). Thus cigarette smoking, which represents a highly significant risk factor in carcinogenesis by itself, protects on the other hand against some additional genotoxic insults.