Beryllium-induced TNF-alpha production is transcription-dependent in chronic beryllium disease

Beryllium (Be)-antigen presentation to Be-specific CD4(+) T cells from the lungs of patients with chronic beryllium disease (CBD) results in T cell proliferation and TNF-alpha secretion. We tested the hypothesis that Be-induced, CBD bronchoalveolar lavage (BAL) T cell, transcription-dependent, TNF-alpha secretion was accompanied by specific transcription factor upregulation. After 6 h of Be stimulation, CBD BAL cells produced a median of 883 pg/ml TNF-alpha (range, 608-1,275 pg/ml) versus 198 pg/ml (range, 116-245 pg/ml) by unstimulated cells. After 12 h CBD BAL cells produced a median of 2,963 pg/ml (range, 99-9,424 pg/ml) TNF-alpha versus 55 pg/ml (range, 0-454) by unstimulated cells. Using real-time RT-PCR, Be-stimulated TNF-alpha production at 6 h was preceded by a 5-fold increase in TNF-alpha pre-mRNA copy number:beta-actin copy number (Be median ratio 0.21; unstimulated median ratio 0.04). The median ratio of mature TNF-alpha mRNA:beta-actin mRNA was upregulated 1.4-fold (Be median ratio 0.17; unstimulated median ratio 0.12). Be exposure in the presence of the transcription inhibitor pentoxifylline (PTX) decreased CBD BAL cell TNF-alpha pre-mRNA levels > 60%, whereas treatment with the mRNA splicing inhibitor 2-aminopurine (2AP) decreased levels 40% relative to Be exposure alone. PTX treatment decreased mature TNF-alpha mRNA levels 50% while 2AP decreased levels > 80%, relative to Be exposure alone. Beryllium exposure specifically upregulated transcription factors AP-1 and NF-kappaB. The data suggest that Be exposure induces transcription-dependent TNF-alpha production, potentially due to upregulation of specific transcription factors.

Am J Respir Cell Mol Biol. 2007 Feb;36(2):191-200. doi: 10.1165/rcmb.2006-0021TR. Epub 2006 Sep 15.

PMID:16980557 | PMC:PMC2176111 | DOI:10.1165/rcmb.2006-0021TR