title: The inhibition of lipopolysaccharide-induced macrophage inflammation by 4 compounds in Hypericum perforatum extract is partially dependent on the activation of SOCS3.
abstract: Our previous studies found that 4 compounds, namely pseudohypericin, amentoflavone, quercetin, and chlorogenic acid, in Hypericum perforatum ethanol extract synergistically inhibited lipopolysaccharide (LPS)-induced macrophage production of prostaglandin E2 (PGE2). Microarray studies led us to hypothesize that these compounds inhibited PGE2 production by activating suppressor of cytokine signaling 3 (SOCS3). In the current study, siRNA was used to knockdown expression of SOCS3 in RAW 264.7 macrophages and investigated the impact of H. perforatum extract and the 4 compounds on inflammatory mediators and cytokines. It was found that the SOCS3 knockdown significantly compromised the inhibition of PGE2 and nitric oxide (NO) by the 4 compounds, but not by the extract. The 4 compounds, but not the extract, decreased interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), while both lowered interleukine-1β. SOCS3 knockdown further decreased IL-6 and TNF-α. Pseudohypericin was the major contributor to the PGE2 and NO inhibition in cells treated with the 4 compounds, and its activity was lost with the SOCS3 knockdown. Cyclooxygenase-2 (COX-2) and inducible NO synthase protein expression were not altered by the treatments, while COX-2 activity was decreased by the extract and the 4 compounds and increased by SOCS3 knockdown. In summary, it was demonstrated that the 4 compounds inhibited LPS-induced PGE2 and NO through SOCS3 activation. The reduction of PGE2 can be partially attributed to COX-2 enzyme activity, which was significantly elevated with SOCS3 knockdown. At the same time, these results also suggest that constituents in H. perforatum extract were alleviating LPS-induced macrophage response through SOCS3 independent mechanisms.
authors.affiliation: The Center for Research on Botanical Dietary Supplements, Iowa State University, Ames, IA 50011, United States. huangnan@iastate.edu
authors.forename: Nan
authors.initials: N
authors.lastname: Huang
authors.forename: Ludmila
authors.initials: L
authors.lastname: Rizshsky
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Hauck
authors.forename: Basil J
authors.initials: BJ
authors.lastname: Nikolau
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Murphy
authors.forename: Diane F
authors.initials: DF
authors.lastname: Birt
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000494:pharmacology; D044946:Biflavonoids / Q000737:chemistry / Q000494:pharmacology; D002460:Cell Line; D002726:Chlorogenic Acid / Q000737:chemistry / Q000494:pharmacology; D016207:Cytokines / Q000276:immunology; D015232:Dinoprostone / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D055785:Gene Knockdown Techniques; D020902:Hypericum / Q000737:chemistry*; D007249:Inflammation / Q000276:immunology*; D018836:Inflammation Mediators / Q000276:immunology; D008070:Lipopolysaccharides / Q000009:adverse effects*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D051379:Mice; D009569:Nitric Oxide / Q000737:chemistry; D010569:Perylene / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D011794:Quercetin / Q000737:chemistry / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000737:chemistry / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D000893:Anti-Inflammatory Agents; D044946:Biflavonoids; D016207:Cytokines; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D034741:RNA, Small Interfering; C491411:Socs3 protein, mouse; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D002726:Chlorogenic Acid; D009569:Nitric Oxide; D000431:Ethanol; D010569:Perylene; C011164:amentoflavone; D011794:Quercetin; D015232:Dinoprostone; C056602:pseudohypericin