Cytokine Inhibition of Fibroblast-Induced Gel Contraction Is Mediated by PGE₂and NO Acting Through Separate Parallel Pathways

Abstract

Contraction of three-dimensional collagen gels is a model of the contraction that characterizes normal healing and remodeling after injury. In the current study, we evaluated the hypothesis that a number of inflammatory factors, including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, and interferon (IFN)-gamma, modulate this process by induction of prostaglandin (PG) E(2) and nitric oxide (NO) production and that these secondary mediators function in an autocrine or paracrine manner to modulate contraction. Human fetal lung fibroblasts (HFL) were cultured in type I collagen gels and floated in medium containing TNF-alpha, IL-1 beta, or IFN-gamma alone or in combination (cytomix). All cytokines inhibited the contraction significantly. The potency order was IL-1 beta, TNF-alpha, IFN-gamma. The cytomix was no more potent than was IL-1 beta alone. PGE(2) production was increased by TNF-alpha (5.0 versus 0.16 ng/ml, P < 0.01), IL-1 beta (5.3 versus 0.16 ng/ml, P < 0.01), and cytomix (5.9 versus 0.16 ng/ml, P < 0.01), and was completely inhibited by indomethacin. Indomethacin (P < 0.05) and L-NG-monomethyl arginine citrate (L-NMMA) (P < 0.05) alone both partially attenuated the inhibition of contraction caused by cytokines alone or by cytomix. Indomethacin and L-NMMA together attenuated inhibition more than either alone (P < 0.05). Exogenous PGE(2) and exogenous NO donors (DETA nononate and 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium chloride) inhibited the contraction significantly. The protein kinase A inhibitor KT5270 and the protein kinase G inhibitor Rp-pCPT-cGMPS attenuated the inhibition induced by PGE(2) and NO, respectively. In summary, PGE(2) and NO appear to function in parallel as autocrine/paracrine mediators of cytokine-driven fibroblast inhibition of the contraction of collagen gels and may contribute to remodeling during repair and inflammation in lung disorders.

Red blood cells increase secretion of matrix metalloproteinases from human lung fibroblasts in vitro

“…Both fibroblast proliferation and protein production in the gels differ markedly from those in monolayer cultures (3). If the gels are floating in cell culture medium the fibroblasts will contract the gels, and this contraction can be modified by a variety of exogenous agents, which either simulate or inhibit the collagen gel contraction (11,48,54,57). In vivo, tissue remodeling is a complex process and can play an important role in many pathophysiological processes in which altered tissue structure leads to loss of function.…”

5-Lipoxygenase and cyclooxygenase regulate wound closure in NIH/3T3 fibroblast monolayers

“…In vivo, in tissue containing multiple cell types, fibroblasts would precede endothelial cells into denuded areas (36) such that the release of arachidonate metabolites from fibroblasts to coordinate their own spreading, bridging, and migration would also likely influence surrounding endothelial, smooth muscle, and neural cells. Endothelial wound closure in small scrape wounds of corneal and vascular endothelium have been reported to occur primarily by enlargement and flattening, or spreading, of peripheral wound cells adjacent to the wound gap (10,30).…”

iNOS affects matrix production in distal lung fibroblasts from patients with mild asthma

“…In other studies, higher doses of exogenous NO have been shown to affect proliferation rate (39) and collagen synthesis (40) and inhibit fibroblast-mediated gel contraction (41). However, high doses of NO may cause peroxynitrite formation, induce oxidative DNA damages and apoptosis (39) and impair collagen synthesis due to toxicity (40).…”