Global response of Plasmodium falciparum to hyperoxia: a combined transcriptomic and proteomic approach

Background: Over its life cycle, the Plasmodium falciparum parasite is exposed to different environmental conditions, particularly to variations in O-2 pressure. For example, the parasite circulates in human venous blood at 5% O-2 pressure and in arterial blood, particularly in the lungs, at 13% O-2 pressure. Moreover, the parasite is exposed to 21% O-2 levels in the salivary glands of mosquitoes. Methods: To study the metabolic adaptation of P. falciparum to different oxygen pressures during the intraerythrocytic cycle, a combined approach using transcriptomic and proteomic techniques was undertaken. Results: Even though hyperoxia lengthens the parasitic cycle, significant transcriptional changes were detected in hyperoxic conditions in the late-ring stage. Using PS 6.0 (TM) software (Ariadne Genomics) for microarray analysis, this study demonstrate up-expression of genes involved in antioxidant systems and down-expression of genes involved in the digestive vacuole metabolism and the glycolysis in favour of mitochondrial respiration. Proteomic analysis revealed increased levels of heat shock proteins, and decreased levels of glycolytic enzymes. Some of this regulation reflected post-transcriptional modifications during the hyperoxia response. Conclusions: These results seem to indicate that hyperoxia activates antioxidant defence systems in parasites to preserve the integrity of its cellular structures. Moreover, environmental constraints seem to induce an energetic metabolism adaptation of P. falciparum. This study provides a better understanding of the adaptive capabilities of P. falciparum to environmental changes and may lead to the development of novel therapeutic targets.