Suppressive effects of PG201, an antiarthritic botanical formulation, on lipopolysaccharide-induced inflammatory mediators in Raw264.7 cells

Abstract

PG201, an ethanol extract from a mixture of 12 herbs, has strong antiarthritic activity. To understand the molecular mechanisms underlying its anti-inflammatory effects, PG201-mediated suppression of inflammatory mediators was studied in Raw264.7, a mouse macrophage cell line. PG201 decreased the expression of interleukin (IL)-1 β, IL-6 and CC chemokine ligand-2, but not tumor necrosis factor- α, at the protein and mRNA levels in lipopolysaccharide-stimulated Raw264.7 cells. Results from a gel retardation assay indicated that PG201 substantially reduced the DNA-binding activity of the activator protein-1 and cyclic adenosine monophosphate-responsive element-binding protein transcription factors, but not nuclear factor- κB. Western blot and Northern blot analyses showed that PG201 reduced inducible nitric oxide synthase and cytosolic phospholipase A2 (cPLA2) protein expression, but did not affect mRNA expression, ultimately resulting in decreased nitric oxide and prostaglandin E2. The protein expression of cPLA2 was decreased by PG201 in the presence of cycloheximide, an inhibitor of translation, suggesting that PG201 may facilitate the degradation of cPLA2. Taken together, these results suggest that PG201 selectively affects the expression of proteins that play key roles in the inflammatory response at transcriptional and post-translational levels.