Differential regulation of cyclooxygenases 1 and 2 by interleukin-1 beta, tumor necrosis factor-alpha, and transforming growth factor-beta 1 in human lung fibroblasts

Abstract

In the present studies we found that incubation of human lung fibroblasts with transforming growth factor-beta 1 (TGF-beta 1) potentiated the interleukin-1 beta (IL-1 beta) and/or tumor necrosis factor-alpha (TNF-alpha)-stimulated production of prostaglandin E2 (PGE2). Analysis of fibroblast proteins showed the induction of cyclooxygenase-1 (Cox-1) by TGF-beta 1 and the induction of Cox-2 by IL-1 beta and TNF-alpha. The levels of transcripts for Cox-1 were minimally modified by IL-1 beta or TNF-alpha, however, they were increased by 12-fold by TGF-beta 1. Transcripts for Cox-2 were induced by IL-1 beta or TNF-alpha and their induction was potentiated by TGF-beta 1. TGF-beta 1 alone did not induce Cox-2 transcripts. In vitro transcription assays showed that IL-1 beta and TNF-alpha increased the transcription of the Cox-2 gene, whereas TGF-beta 1 had no effect. Addition of TGF-beta did not increase further the transcription of Cox-2 in IL-1 beta-treated cells, but increased the stability of the corresponding transcripts. The transcription rate of the Cox-1 gene was not increased by any of the cytokines studied. In summary, we demonstrate that the potentiation of PGE2 production by TGF-beta 1 in IL-1 beta and TNF-alpha-treated fibroblasts is the result of transcriptional stimulation of the Cox-2 gene by IL-1 beta and TNF-alpha and the stabilization of the resulting transcripts by TGF-beta 1.