Related Experiment Videos
Deferoxamine inhibition of malaria is independent of host iron status
1Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Oxford, United Kingdom.
Abstract:
The mechanism whereby deferoxamine (DF) inhibits the growth of malaria parasites was studied in rats infected with Plasmodium berghei. Peak parasitemia was 32.6% (day 14) in untreated controls and 0.15% (day 7) in rats receiving 0.33 mg/g in 8 hourly DF injections, subcutaneously. DF inhibition of parasite growth was achieved without any reduction in transferrin saturation or hemoglobin synthesis and with only a partial (56%) depletion of hepatic iron stores. Dietary iron depletion resulted in anemia (hematocrit 25 vs. 46%), microcytosis (MCV 54 vs. 60 fl), and reduced transferrin saturation (17 vs. 96%) without any effect on infection (peak parasitemia 30 vs. 36%). Similarly, parenteral iron loading with ferric citrate over 10 d (75 mg iron/kg) failed to aggravate infection. In a search for evidence of direct interaction between DF and parasitized erythrocytes, gel filtration and ultrafiltration was performed on hemolysates obtained from in vivo 59Fe-labeled parasitized erythrocytes. This showed that 1.1-1.9% of the intracellular radioiron was located in a chelatable, labile iron pool. Incubation of intact cells with 0-500 microM DF resulted in a proportional increase in intracellular iron chelation, and the chelation of all available labile intracellular iron was completed within 6 h. These observations indicate that the severity of P. berghei infection in rats and its in vivo suppression by DF are independent of host iron status and suggest that DF inhibition of malaria involves intracellular chelation of a labile iron pool in parasitized erythrocytes.
Insights
Deferoxamine (DF) effectively inhibits malaria parasite growth by chelating intracellular iron within red blood cells, independent of the host's overall iron status. This mechanism offers a new perspective on malaria treatment strategies.
Area of Science:
- Malariology
- Pharmacology
- Hematology
Background:
- Deferoxamine (DF) is known to inhibit malaria parasite growth.
- The precise mechanism of DF's action, particularly its relationship with host iron metabolism, requires further elucidation.
Purpose of the Study:
- To investigate the mechanism by which deferoxamine (DF) inhibits Plasmodium berghei malaria parasite growth in rats.
- To determine if DF's efficacy is dependent on host iron status or involves direct interaction with parasitized erythrocytes.
Main Methods:
- Assessing parasite growth and host iron parameters (transferrin saturation, hemoglobin synthesis, hepatic iron stores) in DF-treated and untreated rats.
- Inducing iron deficiency and iron overload in rats to evaluate their impact on infection severity and DF efficacy.
- Utilizing radiolabeled iron (59Fe) and biochemical assays (gel filtration, ultrafiltration) to identify and quantify chelatable iron within parasitized erythrocytes.
Main Results:
- DF significantly inhibited P. berghei parasitemia without altering host transferrin saturation or hemoglobin synthesis, and with only partial depletion of hepatic iron.
- Dietary iron depletion or parenteral iron loading did not affect malaria infection severity.
- A small, labile, chelatable iron pool was identified within parasitized erythrocytes, and DF effectively chelated this intracellular iron within 6 hours.
Conclusions:
- The anti-malarial effect of deferoxamine in P. berghei infected rats is independent of host iron status.
- Deferoxamine's mechanism of action involves the direct intracellular chelation of a labile iron pool within parasitized erythrocytes.
- Targeting intracellular iron in infected erythrocytes presents a potential therapeutic strategy for malaria.