Possible role of heme oxygenase-1 and prostaglandins in the pathogenesis of cerebral malaria: heme oxygenase-1 induction by prostaglandin D(2) and metabolite by a human astrocyte cell line

Abstract

Astrocytes are the most abundant cells in the central nervous system that play roles in maintaining the blood-brain-barrier and in neural injury, including cerebral malaria, a severe complication of Plasmodium falciparum infection. Prostaglandin (PG) D(2) is abundantly produced in the brain and regulates the sleep response. Moreover, PGD(2) is a potential factor derived from P. falciparum within erythrocytes. Heme oxygenase-1 (HO-1) is catalyzing enzyme in heme breakdown process to release iron, carbon monoxide, and biliverdin/bilirubin, and may influence iron supply to the P. falciparum parasites. Here, we showed that treatment of a human astrocyte cell line, CCF-STTG1, with PGD(2) significantly increased the expression levels of HO-1 mRNA by RT-PCR. Western blot analysis showed that PGD(2) treatment increased the level of HO-1 protein, in a dose- and time-dependent manner. Thus, PGD(2) may be involved in the pathogenesis of cerebral malaria by inducing HO-1 expression in malaria patients.

Keywords: Plasmodium falciparum; astrocyte; cerebral malaria; heme oxygenase; iron; prostaglandin D2.

Fig. 1

Effects of PGD₂ and 15dPGJ₂ on HO-1 and HO-2 proteins in CCF-STTG1 cells. CCF-STTG1 human astrocyte cells were treated with PGD₂ (A) or 15d-PGJ₂ (B) at final concentration 0.5, 1, 5, or 10 µM for the indicated time from 3 to 24 hr and then harvested for preparation of proteins. Shown are the Western blots used for HO-1 and HO-2 protein. Each lane contained 30 µg proteins prepared from CCF-STTG1 cells. A bottom panel shows β-actin as an internal control. The data shown are from 1 of 2 independent experiments.

Fig. 2

Expression of HO-1 mRNA by PGD₂ and 15dPGJ₂ in CCF-STTG1 astrocyte cells. CCF-STTG1 cells were treated with PGD₂ or 15d-PGJ₂ at final concentration 0.5, 1, 5, or 10 µM for the indicated time from 3 to 24 hr and then harvested for RNA preparation. cDNA were prepared for RT-PCR using Platinum® SYBR® Green qPCR SuperMix-UDG cocktail (Invitrogen). Shown are representative of the relative HO-1 mRNA and HO-2 mRNA expression of PGD₂ (A, B) or 15d-PGJ₂ (C, D) induction. The data were obtained by dividing the intensity value for each sample with 0-hr untreated control cells, which reflected a basal expression level.