Role of dihydroartemisinin in regulating prostaglandin E2 synthesis cascade and inflammation in endothelial cells.

Endothelial cells (ECs) are crucial in maintaining vascular homeostasis. Endothelial dysfunction was involved in many cardiovascular diseases (CVDs). Recently, antimalarial medicine artemisinin and its derivatives including dihydroartemisinin (DHA) were found to be beneficial in some diseases including CVDs. Prostaglandin (PG) E2 is a known inflammatory mediator and plays important roles in cardiovascular system. This study was to investigate the role of DHA in regulating cyclooxygenase (COX)/PGE synthase (PGES)/PGE2 cascade and inflammation in ECs. After DHA treatment, the mRNA and protein levels of COX-2 were strikingly upregulated in time- and dose-dependent manners. In contrast, COX-1 was significantly downregulated. As expected, inhibition of COX-1 or COX-2 further reduced PGE2 production after DHA treatment. Moreover, DHA enhanced microsomal PGE2 synthase (mPGES)-2 and moderately modulated cytosolic PGE2 synthase (cPGES) with no effect on mPGES-1 expression. Importantly, DHA significantly reduced PGE2 levels in line with the upregulation of 15-hydroxyprostaglandin dehydrogenase (15-PGDH, a key enzyme for prostaglandin degradation). Lastly, we observed that DHA not only reduced the PGE2 levels in tumor necrosis factor-α (TNF-α)-treated ECs but also blunted the upregulation of inflammatory cytokines of interleukin (IL)-6 and IL-1β induced by TNF-α or PGE2. These findings demonstrated an important role of DHA in regulating PGE2 synthesis cascade and inflammation in ECs, suggesting a potential of DHA for the treatment of inflammatory vascular diseases.