A prostaglandin (PG), PGE2, mediates both cellular and humoral immune responses of insects. Spodoptera exigua (Lepidoptera: Noctuidae) biosynthesizes PGE2 by an unknown enzyme. This study predicted the enzyme, which is a novel membrane-bound prostaglandin E synthase-2 (mPGES-2). The transcriptional expression analysis showed the mPGES-2 is inducible to immune challenge. After RNA interference (RNAi), the hemocyte nodulation and expression of eleven antimicrobial peptides were significantly impaired. The RNAi effect was rescued by addition of PGE2 suggesting that mPGES-2 is crucial for immune responses mediated by PGE2.

Cyclooxygenase-2 (COX-2)-mediated prostaglandin E2 (PGE2) plays a key role in development and progression of inflammatory responses and Porphyromonas gingivalis is a common endodontic pathogen. In this study, we investigated induction of COX-2 and PGE2 by P. gingivalis in human dental pulp cells (HDPCs). P. gingivalis increased expression of COX-2, but not that of COX-1. Increased levels of PGE2 were released from P. gingivalis-infected HDPCs and this PGE2 increase was blocked by celecoxib, a selective COX-2 inhibitor. P. gingivalis activated all three types of mitogen-activated protein kinases (MAPKs). P. gingivalis-induced activation of nuclear factor-κB (NF-κB) was demonstrated by the results of phosphorylation of NF-κ B p65 and degradation of inhibitor of κB-α (IκB-α). Pharmacological inhibition of each of the three types of MAPKs and NF-κB substantially attenuated P. gingivalisinduced PGE2 production. These results suggest that P. gingivalis should promote endodontic inflammation by stimulating dental pulp cells to produce PGE2.

Arabis glabra is a localized common rhizomatous flowering plant, This plant is often used in Korean traditional systems of medicine as a remedy for blood cleaning, detoxification, abscess, gastrospasm, arthritis, contraction and diarrhea. Generally drugs that are used for arthritis have antinociceptive and anti-inflammatory properties. However, validity of the anti-inflammatory activity has not been scientifically investigated so far. Therefore, the aim of this study was to investigate the anti-inflammatory potential of A. glabra using the ethanolic extract and its sub-fractions. To evaluate the anti-inflammatory effects, we examined the inflammatory mediators such as nitric oxide (NO) and prostaglandin E2 (PGE2) on RAW 264.7macrophages. Our results indicated that hexane and chloroform fraction significantly inhibited the LPSinduced NO and PGE2 production in the cells. The hexane fraction inhibitory activity for NO tests with IC50 values showed in 21.0 ㎍/㎖. The chloroform fraction inhibitory activity for PGE2 tests with IC50 values showed in 18.0 ㎍/㎖. These efficacy are expected to be able to present the potential for the development of health functional food for the prevention inflammatory diseases because it has sufficient preventive medical possibilities. Further, it is determined that it is necessary to further study the mechanism of cytokine and protein expression associated with inflammation.

Prostaglandin (PG) E2 is an important mediator of skin wound healing without excessive scarring and gastric ulcer healing. However, PGE2 has a short lifetime in vivo because it is metabolized rapidly by 15-hydroxyprostaglandin dehydrogenase (15-PGDH). Ethanol extract of Eriobotryae folium (EFEE) elevated intracellular and extracellular PGE2 levels in HaCaT cells and inhibited 15-PGDH (ED50 : 168.4μg/mL) with relatively low cytotoxicity (IC50 : 250.0μg/mL). Real-time PCR analysis showed that mRNA expression of cyclooxygenase (COX)-1 and COX-2 enzymes were increased and prostaglandin transporter (PGT) was decreased in HaCaT cells by EFEE. Moreover, wound healing effect of EFEE (168.4μg/mL) was comparable to that of TGF-β1 (300 pg/mL) as a positive control. These results demonstrate that EFEE may be valuable therapeutic materials for the treatment of PGE2 level dependent diseases.

To search for immunoactive natural products exerting anti-inflammatory activity, we have evaluated the effects on the water extracts of Artemisia princeps Pampanini (APP) on lipopolysaccharide-induced nitric oxide (NO), tumor necrosis factor-α (TNF-α), and prostaglandin E2 (PGE2) production by RAW 264.7 macrophage cell line. Our data indicate that this extract is a potent inhibitor of NO production and it also significantly decreased PGE2 and TNF-α production. Consistent with these results, the protein and mRNA expression level of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) was inhibited by water extracts of APP in a dose-dependent manner. These results suggest that APP may exert anti-inflammatory and analgesic effects possibly by suppressing the inducible NO synthase and COX-2 expressions.