Regulation of rat pulmonary artery endothelial cell transforming growth factor-beta production by IL-1 beta and tumor necrosis factor-alpha.
Recent studies suggest that transforming growth factor-beta (TGF-beta) production is up-regulated at sites of tissue injury, inflammation and repair, or fibrosis. Endothelial cells represent a potentially important in vivo source of TGF-beta; however, the identity of endogenous modulators of TGF-beta production by these cells remains unclear. To address this issue, the effects of the cytokines, IL-1 beta, and TNF-alpha on TGF-beta production by rat pulmonary artery endothelial cells were examined. Conditioned media from cells treated with 0 to 20 ng/ml IL-1 beta and/or TNF-alpha were assayed for TGF-beta activity using a mink lung epithelial cell line. The results show that rat pulmonary artery endothelial cells secreted undetectable amounts of active TGF-beta in the absence of cytokines. However, upon acidification of the conditioned media before assay, a time-dependent increase in TGF-beta activity was noted in media from both untreated and cytokine-treated cells. However, both IL-1 beta and TNF-alpha treatment caused the secretion of significantly greater amounts of TGF-beta activity than control cells, in a dose-dependent manner, with maximal response obtained at cytokine doses of greater than 10 ng/ml. At equivalent doses of cytokine tested, the magnitude of the response was significantly greater with IL-1 beta. These responses were paralleled by increases in steady state mRNA levels for TGF-beta 1. Addition of both cytokines resulted in a synergistic response. Synergism with IL-1 beta was also noted with the fibrogenic agent bleomycin. Kinetic studies indicated that a minimum of 4 h of treatment with either IL-1 beta or TNF-alpha was required for detection of significant increases in either secreted TGF-beta activity or steady state TGF-beta 1 mRNA levels. Thus, endothelial cells could play a role in various TGF-beta-dependent processes in vivo, in situations wherein IL-1 beta and/or TNF-alpha may be present at comparable concentrations.
Phan
S H
SH
Department of Pathology, University of Michigan Medical School, Ann Arbor 48109.
Gharaee-Kermani
M
M
McGarry
B
B
Kunkel
S L
SL
Wolber
F W
FW
D000818:Animals; D001761:Bleomycin / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004730:Endothelium, Vascular / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology*; D011651:Pulmonary Artery; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000096:biosynthesis* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D007375:Interleukin-1; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D001761:Bleomycin