Platelet-derived growth factor and transforming growth factor beta synergistically potentiate inflammatory mediator synthesis by fibroblast-like synoviocytes.

Abstract

INTRODUCTION:

The objective of this study was to model the effects of transforming growth factor beta (TGF-beta) and platelet-derived growth factor (PDGF), both present in rheumatoid arthritis (RA) synovia, on the behavior of fibroblast-like synoviocytes (FLS) in response to pro-inflammatory cytokine (interleukin (IL)1beta, tumor necrosis factor-alpha (TNFalpha)) challenge.

METHODS:

Gene and protein expression by fibroblast-like synoviocytes in vitro was studied by quantitative Polymerase Chain Reaction (qPCR), ELISA and multiplex bead cytokine assays. Intracellular signaling pathway activation was determined by Western blot for phospho-kinases and the use of specific inhibitors.

RESULTS:

In combination, TGF-beta and PDGF (2GF) synergistically augmented TNFalpha- or IL1beta-induced matrix metalloproteinase 3 (MMP3), IL6, IL8, and macrophage inflammatory protein 1 alpha (MIP1alpha) secretion by FLS. Other FLS-derived mediators remained unaffected. Individually, neither growth factor significantly potentiated TNFalpha or IL1beta-induced MMP3 secretion, and only slightly enhanced IL6. The effect of 2GF on TNFalpha-induced gene expression was transcriptionally mediated; blocked by imatinib mesylate; and occurred even if 2GF was added as much as four hours prior to TNFalpha. In addition, a 15-minute pulse of 2GF four hours prior to TNFalpha stimulation yielded a synergistic response. The extracellular-signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K) signaling pathways were induced for at least four hours by 2GF, as demonstrated by persistently upregulated levels of phospho-Akt and phospho-ERK. However, pharmacologic inhibitor studies demonstrated that the potentiating action of 2GF was dependent on PI3 kinase only, and not on ERK.

CONCLUSIONS:

The combination of PDGF and TGF-beta dramatically potentiates FLS response to cytokines in a receptor-mediated and PI3 kinase-dependent fashion. These data suggest that 2GF contribute to synovitis by directing synovial fibroblasts toward a more aggressive phenotype in response to TNFalpha. Therefore, inhibition of growth factor signaling may constitute a complementary therapeutic approach to cytokine-targeted treatments for RA.

• Authors: Sanna Rosengren, Maripat Corr, David L Boyle
• Journal: Arthritis research & therapy (Arthritis Res Ther) Vol. 12 Issue 2 Pg. R65 ( 2010) ISSN: 1478-6362 [Electronic] England
• PMID: 20380722 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Benzamides
• Cytokines
• Matrix Metalloproteinase Inhibitors
• Piperazines
• Platelet-Derived Growth Factor
• Protein Kinase Inhibitors
• Proto-Oncogene Proteins c-sis
• Pyrimidines
• RNA, Messenger
• Transforming Growth Factor beta
• Becaplermin
• Imatinib Mesylate
• Matrix Metalloproteinases

Topics

• Becaplermin
• Benzamides
• Cells, Cultured
• Cytokines (genetics, metabolism)
• Drug Synergism
• Fibroblasts (cytology, drug effects, metabolism)
• Gene Expression
• Humans
• Imatinib Mesylate
• Matrix Metalloproteinase Inhibitors
• Matrix Metalloproteinases (genetics, metabolism)
• Piperazines (pharmacology)
• Platelet-Derived Growth Factor (pharmacology)
• Protein Kinase Inhibitors (pharmacology)
• Proto-Oncogene Proteins c-sis
• Pyrimidines (pharmacology)
• RNA, Messenger (metabolism)
• Signal Transduction (drug effects)
• Synovial Membrane (cytology, drug effects, metabolism)
• Transforming Growth Factor beta (pharmacology)