The filarial parasite Onchocerca volvulus generates the lipid mediator prostaglandin E2

Prostaglandins exhibit regulatory effects on the vascular and immune system. Prostaglandin E2 (PGE2) modulates T helper (Th) cell and effector cell functional reactivity, thereby promoting Th2 responses. We found significant expression of PGE2 in male and female Onchocerca volvulus. Using immunohistology, PGE2 was predominantly detected in the hypodermis of adult O. volvulus, the metabolically most active tissue of the filaria. In contrast, the muscles were PGE2-negative and the epithelia of intestine and uterus and male genital tract showed only weak staining. Oocytes were well labeled whereas embryos and sperms did not react. Less pronounced PGE2 staining was observed in some dermal microfilariae. The expression of PGE2 was found independent of antifilarial (ivermectin) as well as anti-endobacterial (doxycycline) treatment of O. volvulus-infected patients. PGE2 was also demonstrated in extracts of adult worms by high-performance liquid chromatography–mass spectrometry. Release of PGE2 from live or moribund filariae can affect the host ´ s metabolism and immune response in favor of the filarial parasite.