Inflammatory cytokines mediate C-C (monocyte chemotactic protein 1) and C-X-C (interleukin 8) chemokine expression in human pleural fibroblasts.
ABSTRACT Current knowledge implicates pleural mesothelial cells as mainly responsible for inflammatory responses in the pleural space. However, a vast body of recent evidence underscores the important role of fibroblasts in the process of inflammation in several types of tissues. We hypothesize that HPFBs (human pleural fibroblasts) play an important role in pleural responses and also when activated by bacterial endotoxin LPS (lipopolysaccharide), IL-1 beta (interleukin-1 beta), or TNF-alpha (tumor necrosis factor-alpha) release of C-C and C-X-C chemokines-specifically, MCP-1 and IL-8. Our results show that pleural fluid-isolated human fibroblasts release IL-8 and MCP-1 upon stimulation with IL-1 beta, TNF-alpha, and LPS in both a concentration- and time-dependent manner. RT-PCR (reverse-transcriptase-polymerase chain reaction) studies have also confirmed IL-8- and MCP-1-specific mRNA expression in activated pleural fibroblasts. On the time-dependent response curve, IL-8 was found in maximum concentrations at 144 hr, whereas MCP-1 continued to increase even after 196 hr following stimulation. IL-1 beta induced the maximum release of IL-8 (800-fold) and MCP-1 (164-fold), as compared to the controls. TNF-alpha induced a 95-fold increase in IL-8 and an 84-fold increase in MCP-1 levels, as compared to the controls. Collectively, our results show that human pleural fibroblasts contribute to the inflammatory cascade in the pleural space.
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ABSTRACT: Monocyte chemoattractant protein-1 (MCP-1) has been implicated in many inflammatory and autoimmune diseases. The G-protein-coupled receptor CCR-2B is probably the most important MCP-1 receptor in vivo, and loss of MCP-1 effector function alone is sufficient to impair monocytic trafficking in inflammation models. MCP-1 signalling appears to be a relevant target, especially in rheumatoid arthritis (RA). In RA patients, MCP-1 is produced by synovial cells and infiltrating monocytes, plasma MCP-1 concentrations correlate with swollen joint count, and elevated serum MCP-1 concentrations were found in juvenile RA in patients with active disease. Modulation of MCP-1 signalling in experimental RA showed beneficial effects on inflammation and joint destruction. With respect to chronic neuroinflammation, a critical role for MCP-1 has been established in animal models for multiple sclerosis. In acute neuroinflammation, experimental evidence for a detrimental role of MCP-1 in stroke and excitotoxic injury has been found. Several selective small molecular weight CCR-2B antagonists and MCP-1-blocking antibodies have been described. The proof for the validity of targeting MCP-1 signalling in disease, however, has yet to be established in clinical trials.Expert Opinion on Therapeutic Targets 03/2003; 7(1):35-48. DOI:10.1517/14728126.96.36.199 · 4.90 Impact Factor
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ABSTRACT: Monocyte/macrophage infiltration to the subendothelial space of arterial wall is a critical initial step in atherogenesis, in which CC chemokine ligand 2 (CCL2)/monocyte chemoattractant protein-1 (MCP-1) is thought to play a key role. This study investigated the effectiveness of phosphodiesterase inhibitors, including the nonselective pentoxifylline (PTX) and the selective type III (cilostamide) and type IV (denbufylline) inhibitors, on cytokine-induced CCL2/MCP-1 production in cultured rat vascular smooth muscle cells (VSMCs), and the signal transduction mechanisms whereby they act. Our results showed that tumor necrosis factor (TNF)-alpha induced a marked increase in CCL2/MCP-1 production in dose- and time-dependent manners. 2-(2-Amino-3-methoxyphenyl)-4H-1-benzopyran-4-one (PD98059), 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio) butadiene (U0126) [both inhibitors of p42/44 mitogen-activated protein kinase (MAPK) kinase], and anthra[1hyphen]9-cd]pyrazol-6(2H)-one (SP600125) [an inhibitor of c-Jun NH(2)-terminal kinases (JNKs)] attenuated TNF-alpha-induced CCL2/MCP-1 production, without affecting I-kappaBalpha degradation or p65/nuclear factor-kappaB (NF-kappaB) nuclear translocation. PD98059 abolished TNF-alpha-activated p42/44 MAPK phosphorylation and c-Fos up-regulation, whereas SP600125 inhibited TNF-alpha-activated JNK and c-Jun phosphorylation. The NF-kappaB inhibitor carbobenzoxy-l-leucyl-l-leucyl-l-leucinal (MG132) attenuated TNF-alpha-induced CCL2/MCP-1 production in the presence of increased phospho-JNK and phospho-c-Jun levels. When SP600125 was added simultaneously, MG132 completely inhibited TNF-alpha-induced CCL2/MCP-1 production. Finally, the pretreatment of VSMCs with PTX or cilostamide, but not denbufylline, reduced TNF-alpha-induced CCL2/MCP-1 production, which was preceded by attenuation of p65/NF-kappaB nuclear translocation, p42/44 MAPK, and JNK-c-Jun phosphorylation, and c-Fos up-regulation. These data indicate that TNF-alpha-stimulated CCL2/MCP-1 production in rat VSMCs is dually regulated by activator protein-1 (AP-1) and NF-kappaB pathways, and inhibition of type III phosphodiesterase contributes substantially to the suppressive effect of PTX on CCL2/MCP-1 production via down-regulation of AP-1 and NF-kappaB signals.Journal of Pharmacology and Experimental Therapeutics 07/2004; 309(3):978-86. DOI:10.1124/jpet.103.062620 · 3.86 Impact Factor
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ABSTRACT: The role played by resident pleural macrophages in the initiation of pleural inflammation is currently unclear. To evaluate the role of resident pleural macrophages in the initiation of inflammation. We have used a conditional macrophage ablation strategy to determine the role of resident pleural macrophages in the regulation of neutrophil recruitment in a murine model of experimental pleurisy induced by the administration of carrageenan and formalin- fixed Staphylococcus aureus. Conditional macrophage ablation mice express the human diphtheria toxin receptor under the control of the CD11b promoter such that the administration of diphtheria toxin induces ablation of nearly 97% of resident macrophages. Ablation of resident pleural macrophages before the administration of carrageenan or S. aureus dramatically reduced neutrophil influx into the pleural cavity. In the carrageenan model, the reduction in neutrophil infiltration was associated with marked early reduction in the level of macrophage inflammatory protein 2 as well as reduced levels of various cytokines, including tumor necrosis factor alpha, interleukin 6, and interleukin 10. Adoptive transfer of nontransgenic macrophages partially restored neutrophil infiltration. We also stimulated macrophage-depleted and nondepleted pleural cell populations with carrageenan in vitro and determined the production of chemokines and cytokines. Chemokine and cytokine production was markedly reduced by macrophage depletion, reinforcing the role of resident pleural macrophages in the generation of mediators that initiate acute inflammation. These studies indicate a critical role for resident pleural macrophages in sensing perturbation to the local microenvironment and orchestrating subsequent neutrophil infiltration.American Journal of Respiratory and Critical Care Medicine 04/2006; 173(5):540-7. DOI:10.1164/rccm.200504-538OC · 11.99 Impact Factor