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Evidence for the contribution of the hemozoin synthesis pathway of the murine Plasmodium yoelii to the resistance to artemisinin-related drugs.

Witkowski B, Lelièvre J, Nicolau-Travers ML, Iriart X, Njomnang Soh P, Bousejra-Elgarah F, Meunier B, Berry A, Benoit-Vical F - PLoS ONE (2012)

Bottom Line: Finally, we confirmed that artemisinins act also like quinolines against Plasmodium via hemozoin production inhibition.These results should help both to reinforce the artemisinins activity and avoid emergence and spread of endoperoxides resistance by focusing in adequate drug partners design.Such considerations appear crucial in the current context of early artemisinin resistance in Asia.

View Article: PubMed Central - PubMed

Affiliation: CNRS, Laboratoire de Chimie de Coordination, and Université de Toulouse Paul Sabatier, UPS, INPT, LCC, Toulouse, France.

ABSTRACT
Plasmodium falciparum malaria is a major global health problem, causing approximately 780,000 deaths each year. In response to the spreading of P. falciparum drug resistance, WHO recommended in 2001 to use artemisinin derivatives in combination with a partner drug (called ACT) as first-line treatment for uncomplicated falciparum malaria, and most malaria-endemic countries have since changed their treatment policies accordingly. Currently, ACT are often the last treatments that can effectively and rapidly cure P. falciparum infections permitting to significantly decrease the mortality and the morbidity due to malaria. However, alarming signs of emerging resistance to artemisinin derivatives along the Thai-Cambodian border are of major concern. Through long-term in vivo pressures, we have been able to select a murine malaria model resistant to artemisinins. We demonstrated that the resistance of Plasmodium to artemisinin-based compounds depends on alterations of heme metabolism and on a loss of hemozoin formation linked to the down-expression of the recently identified Heme Detoxification Protein (HDP). These artemisinins resistant strains could be able to detoxify the free heme by an alternative catabolism pathway involving glutathione (GSH)-mediation. Finally, we confirmed that artemisinins act also like quinolines against Plasmodium via hemozoin production inhibition. The work proposed here described the mechanism of action of this class of molecules and the resistance to artemisinins of this model. These results should help both to reinforce the artemisinins activity and avoid emergence and spread of endoperoxides resistance by focusing in adequate drug partners design. Such considerations appear crucial in the current context of early artemisinin resistance in Asia.

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Scheme of Heme catabolim pathways in Plasmodium.Pathway A: GSH mediated heme catabolism. Pathway B: hemozoin biocrystallisation heme mediated catabolism. The pathway B is the standard way of heme catobolism, in majority present in sensitive and revertant lines instead of way A should be predominant in the resistance selected lines presented here. CYT : cytoplasm; FV: food vacuole; RBC: red blood cell.
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pone-0032620-g007: Scheme of Heme catabolim pathways in Plasmodium.Pathway A: GSH mediated heme catabolism. Pathway B: hemozoin biocrystallisation heme mediated catabolism. The pathway B is the standard way of heme catobolism, in majority present in sensitive and revertant lines instead of way A should be predominant in the resistance selected lines presented here. CYT : cytoplasm; FV: food vacuole; RBC: red blood cell.

Mentions: As pyhdp is still not annotated in available databases (PlasmoDB, GeneBank), a partial sequencing of pyhdp was therefore carried out (Figure 6). No SNP were found to explain the lowered concentration of Hz in the selected lines. Nevertheless, mRNA quantification revealed that HDP was statistically under expressed in resistant lines compared with the Y-control line (p = 0.017) (Figure 3B) whereas the gene coding for HDP protein couldn't be deleted in Plasmodium highlighting the crucial presence of that gene for parasite viability [23]. This last finding corroborated the results obtained for the Hz concentrations in the resistant lines, thus confirming that HDP expression might be linked to lysosomotropic drug multi-resistance (Figure 7). This lower expression could be explained by the useless transcription of that gene upon the possible diminution of the Hz synthesis pathway. And thus the decrease in the Hz-based heme degradation pathway suggested the existence of a substitute pathway necessary to eliminate the toxic free heme (Figure 7). As a plausible alternative pathway was via glutathione-mediated heme detoxification [24], a comparison of the reduced glutathione (GSH) concentrations in the resistant lines versus the Y-control was carried out. The results showed that the concentrations of GSH were statistically higher in the resistant lines tested (p = 0.002) (Table 5). As expected, the GSH concentrations fell dramatically after the release of drug pressure to reach the level observed in the Y-control line (Table 5).


Evidence for the contribution of the hemozoin synthesis pathway of the murine Plasmodium yoelii to the resistance to artemisinin-related drugs.

Witkowski B, Lelièvre J, Nicolau-Travers ML, Iriart X, Njomnang Soh P, Bousejra-Elgarah F, Meunier B, Berry A, Benoit-Vical F - PLoS ONE (2012)

Scheme of Heme catabolim pathways in Plasmodium.Pathway A: GSH mediated heme catabolism. Pathway B: hemozoin biocrystallisation heme mediated catabolism. The pathway B is the standard way of heme catobolism, in majority present in sensitive and revertant lines instead of way A should be predominant in the resistance selected lines presented here. CYT : cytoplasm; FV: food vacuole; RBC: red blood cell.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3293827&req=5

pone-0032620-g007: Scheme of Heme catabolim pathways in Plasmodium.Pathway A: GSH mediated heme catabolism. Pathway B: hemozoin biocrystallisation heme mediated catabolism. The pathway B is the standard way of heme catobolism, in majority present in sensitive and revertant lines instead of way A should be predominant in the resistance selected lines presented here. CYT : cytoplasm; FV: food vacuole; RBC: red blood cell.
Mentions: As pyhdp is still not annotated in available databases (PlasmoDB, GeneBank), a partial sequencing of pyhdp was therefore carried out (Figure 6). No SNP were found to explain the lowered concentration of Hz in the selected lines. Nevertheless, mRNA quantification revealed that HDP was statistically under expressed in resistant lines compared with the Y-control line (p = 0.017) (Figure 3B) whereas the gene coding for HDP protein couldn't be deleted in Plasmodium highlighting the crucial presence of that gene for parasite viability [23]. This last finding corroborated the results obtained for the Hz concentrations in the resistant lines, thus confirming that HDP expression might be linked to lysosomotropic drug multi-resistance (Figure 7). This lower expression could be explained by the useless transcription of that gene upon the possible diminution of the Hz synthesis pathway. And thus the decrease in the Hz-based heme degradation pathway suggested the existence of a substitute pathway necessary to eliminate the toxic free heme (Figure 7). As a plausible alternative pathway was via glutathione-mediated heme detoxification [24], a comparison of the reduced glutathione (GSH) concentrations in the resistant lines versus the Y-control was carried out. The results showed that the concentrations of GSH were statistically higher in the resistant lines tested (p = 0.002) (Table 5). As expected, the GSH concentrations fell dramatically after the release of drug pressure to reach the level observed in the Y-control line (Table 5).

Bottom Line: Finally, we confirmed that artemisinins act also like quinolines against Plasmodium via hemozoin production inhibition.These results should help both to reinforce the artemisinins activity and avoid emergence and spread of endoperoxides resistance by focusing in adequate drug partners design.Such considerations appear crucial in the current context of early artemisinin resistance in Asia.

View Article: PubMed Central - PubMed

Affiliation: CNRS, Laboratoire de Chimie de Coordination, and Université de Toulouse Paul Sabatier, UPS, INPT, LCC, Toulouse, France.

ABSTRACT
Plasmodium falciparum malaria is a major global health problem, causing approximately 780,000 deaths each year. In response to the spreading of P. falciparum drug resistance, WHO recommended in 2001 to use artemisinin derivatives in combination with a partner drug (called ACT) as first-line treatment for uncomplicated falciparum malaria, and most malaria-endemic countries have since changed their treatment policies accordingly. Currently, ACT are often the last treatments that can effectively and rapidly cure P. falciparum infections permitting to significantly decrease the mortality and the morbidity due to malaria. However, alarming signs of emerging resistance to artemisinin derivatives along the Thai-Cambodian border are of major concern. Through long-term in vivo pressures, we have been able to select a murine malaria model resistant to artemisinins. We demonstrated that the resistance of Plasmodium to artemisinin-based compounds depends on alterations of heme metabolism and on a loss of hemozoin formation linked to the down-expression of the recently identified Heme Detoxification Protein (HDP). These artemisinins resistant strains could be able to detoxify the free heme by an alternative catabolism pathway involving glutathione (GSH)-mediation. Finally, we confirmed that artemisinins act also like quinolines against Plasmodium via hemozoin production inhibition. The work proposed here described the mechanism of action of this class of molecules and the resistance to artemisinins of this model. These results should help both to reinforce the artemisinins activity and avoid emergence and spread of endoperoxides resistance by focusing in adequate drug partners design. Such considerations appear crucial in the current context of early artemisinin resistance in Asia.

Show MeSH
Related in: MedlinePlus