Beryllium-stimulated apoptosis in macrophage cell lines.
In vitro stimulation of bronchoalveolar lavage cells from patients with chronic beryllium disease (CBD) induces the production of TNF-alpha. We tested the hypothesis that beryllium (Be)-stimulated TNF-alpha might induce apoptosis in mouse and human macrophage cell lines. These cell lines were selected because they produce a range of Be-stimulated TNF-alpha. The mouse macrophage cell line H36.12j produces high levels of Be-stimulated TNF-alpha. The mouse macrophage cell line P388D.1 produces low, constitutive, levels of TNF-alpha and does not up-regulate Be-stimulated TNF-alpha production. The DEOHS-1 human CBD macrophage cell line does not produce constitutive or Be-stimulated TNF-alpha. Apoptosis was determined by microscopic observation of propidium iodide stained fragmented nuclei in unstimulated and BeSO(4)-stimulated macrophage cell lines. BeSO(4) induced apoptosis in all macrophage cell lines tested. Beryllium-stimulated apoptosis was dose-responsive and maximal after 24 h of exposure to 100 microM BeSO(4). In contrast, unstimulated and Al(2)(SO(4))(3)-stimulated macrophage cell lines did not undergo apoptosis. The general caspase inhibitor BD-fmk inhibited Be-stimulated macrophage cell line apoptosis at concentrations above 50 microM. Our data show that Be-stimulated macrophage cell line apoptosis was caspase-dependent and not solely dependent on Be-stimulated TNF-alpha levels. We speculate that the release of Be-antigen from apoptotic macrophages may serve to re-introduce Be material back into the lung microenvironment, make it available for uptake by new macrophages, and thereby amplify Be-stimulated cytokine production, promoting ongoing inflammation and granuloma maintenance in CBD.
Sawyer
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RT
Division of Environmental and Occupational Health Sciences, Department of Medicine, D309 Neustadt, National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206, USA. sawyerr@njc.org
Fadok
V A
VA
Kittle
L A
LA
Maier
L A
LA
Newman
L S
LS
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001607:Berylliosis / Q000097:blood / Q000209:etiology / Q000473:pathology; D001608:Beryllium / Q000009:adverse effects / Q000494:pharmacology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002460:Cell Line; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016273:Occupational Exposure / Q000009:adverse effects; D010586:Phagocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D014409:Tumor Necrosis Factor-alpha; D001608:Beryllium