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Refractoriness of eryptotic red blood cells to Plasmodium falciparum infection: a putative host defense mechanism limiting parasitaemia.

Totino PR, Daniel-Ribeiro CT, Ferreira-da-Cruz Mde F - PLoS ONE (2011)

Bottom Line: Schizont parasitized RBC concentrated by magnetic separation were cultured with eryptotic RBC obtained by ionomycin treatment and, then, parasite growth was evaluated in Giemsa-stained thin blood smears.While parasites infected and developed normally in control non-eryptotic RBC, cultures performed with eryptotic RBC had a marked decrease in parasitaemia.It was noteworthy a great number of free merozoites in eryptotic RBC cultures, indicating that these cells were not susceptible to invasion.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Malaria Research, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brasil.

ABSTRACT
Recently, we have described that apoptosis-like process of red blood cells (RBC) - eryptosis - in malaria is not restricted to parasitized cells, occurring also in non-parasitized RBC (nRBC). Besides to pathogenic proprieties, apoptosis also participates in the innate defense trough restriction of intracellular pathogens propagation. In the present study, we investigated the capacity of P. falciparum parasites to infect eryptotic RBC. Schizont parasitized RBC concentrated by magnetic separation were cultured with eryptotic RBC obtained by ionomycin treatment and, then, parasite growth was evaluated in Giemsa-stained thin blood smears. While parasites infected and developed normally in control non-eryptotic RBC, cultures performed with eryptotic RBC had a marked decrease in parasitaemia. It was noteworthy a great number of free merozoites in eryptotic RBC cultures, indicating that these cells were not susceptible to invasion. We suggest that although eryptosis could be involved in malaria pathogenesis, it could also acting protectively by controlling parasite propagation.

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Effect of ionomycin in P. falciparum parasite growth.Asynchronous cultures (0 h) were maintained for 18 h in presence of ionomycin or lysates of non-treated (nL) or ionomycin-treated (iL) RBC and, then, parasite growth was evaluated in Giemsa-stained thin blood smears. Non-treated cultures were used as control. Data represent mean±S.D. of parasitaemia of the cultures performed in fiveplicate. *** indicates significant difference (p<0.001; ANOVA) from initial culture (0 h).
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pone-0026575-g003: Effect of ionomycin in P. falciparum parasite growth.Asynchronous cultures (0 h) were maintained for 18 h in presence of ionomycin or lysates of non-treated (nL) or ionomycin-treated (iL) RBC and, then, parasite growth was evaluated in Giemsa-stained thin blood smears. Non-treated cultures were used as control. Data represent mean±S.D. of parasitaemia of the cultures performed in fiveplicate. *** indicates significant difference (p<0.001; ANOVA) from initial culture (0 h).

Mentions: As expected, P. falciparum parasites infected and developed normally in control non-eryptotic RBC (Figure 2), showing after 16 and 60 h of culture (periods in which parasite invasion was evaluated) a significant increase of 258,5% and 493,6% in parasitaemia, respectively, when compared with initial culture (0 h). Conversely, cultures performed with eryptotic RBC had a marked decrease of 82.3% in parasitaemia after 16 h, reaching 98.9% of reduction at 60 h (Figure 2). It was noteworthy a great number of free merozoites adhered or not to eryptotic RBC after 16 h of culture (Figure 2B), indicating that these cells were not susceptible to invasion. In addition, developing parasites in cultures maintained with eryptotic RBC were only observed in cells showing normal size (Figure 2B – 36 and 60 h), which should correspond to the RBC non-susceptible to ionomycin-induced eryptosis (Figure 1) or those remained after the procedure of pRBC concentration (see material and methods). The presence of developing parasite in ionomycin-treated RBC should indicate that ionomycin pre-treatment did not interfere with parasite viability. Indeed, lysate of ionomycin-treated RBC or, even, ionomycin alone were not able to inhibit parasite growth in culture (Figure 3).


Refractoriness of eryptotic red blood cells to Plasmodium falciparum infection: a putative host defense mechanism limiting parasitaemia.

Totino PR, Daniel-Ribeiro CT, Ferreira-da-Cruz Mde F - PLoS ONE (2011)

Effect of ionomycin in P. falciparum parasite growth.Asynchronous cultures (0 h) were maintained for 18 h in presence of ionomycin or lysates of non-treated (nL) or ionomycin-treated (iL) RBC and, then, parasite growth was evaluated in Giemsa-stained thin blood smears. Non-treated cultures were used as control. Data represent mean±S.D. of parasitaemia of the cultures performed in fiveplicate. *** indicates significant difference (p<0.001; ANOVA) from initial culture (0 h).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198779&req=5

pone-0026575-g003: Effect of ionomycin in P. falciparum parasite growth.Asynchronous cultures (0 h) were maintained for 18 h in presence of ionomycin or lysates of non-treated (nL) or ionomycin-treated (iL) RBC and, then, parasite growth was evaluated in Giemsa-stained thin blood smears. Non-treated cultures were used as control. Data represent mean±S.D. of parasitaemia of the cultures performed in fiveplicate. *** indicates significant difference (p<0.001; ANOVA) from initial culture (0 h).
Mentions: As expected, P. falciparum parasites infected and developed normally in control non-eryptotic RBC (Figure 2), showing after 16 and 60 h of culture (periods in which parasite invasion was evaluated) a significant increase of 258,5% and 493,6% in parasitaemia, respectively, when compared with initial culture (0 h). Conversely, cultures performed with eryptotic RBC had a marked decrease of 82.3% in parasitaemia after 16 h, reaching 98.9% of reduction at 60 h (Figure 2). It was noteworthy a great number of free merozoites adhered or not to eryptotic RBC after 16 h of culture (Figure 2B), indicating that these cells were not susceptible to invasion. In addition, developing parasites in cultures maintained with eryptotic RBC were only observed in cells showing normal size (Figure 2B – 36 and 60 h), which should correspond to the RBC non-susceptible to ionomycin-induced eryptosis (Figure 1) or those remained after the procedure of pRBC concentration (see material and methods). The presence of developing parasite in ionomycin-treated RBC should indicate that ionomycin pre-treatment did not interfere with parasite viability. Indeed, lysate of ionomycin-treated RBC or, even, ionomycin alone were not able to inhibit parasite growth in culture (Figure 3).

Bottom Line: Schizont parasitized RBC concentrated by magnetic separation were cultured with eryptotic RBC obtained by ionomycin treatment and, then, parasite growth was evaluated in Giemsa-stained thin blood smears.While parasites infected and developed normally in control non-eryptotic RBC, cultures performed with eryptotic RBC had a marked decrease in parasitaemia.It was noteworthy a great number of free merozoites in eryptotic RBC cultures, indicating that these cells were not susceptible to invasion.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Malaria Research, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brasil.

ABSTRACT
Recently, we have described that apoptosis-like process of red blood cells (RBC) - eryptosis - in malaria is not restricted to parasitized cells, occurring also in non-parasitized RBC (nRBC). Besides to pathogenic proprieties, apoptosis also participates in the innate defense trough restriction of intracellular pathogens propagation. In the present study, we investigated the capacity of P. falciparum parasites to infect eryptotic RBC. Schizont parasitized RBC concentrated by magnetic separation were cultured with eryptotic RBC obtained by ionomycin treatment and, then, parasite growth was evaluated in Giemsa-stained thin blood smears. While parasites infected and developed normally in control non-eryptotic RBC, cultures performed with eryptotic RBC had a marked decrease in parasitaemia. It was noteworthy a great number of free merozoites in eryptotic RBC cultures, indicating that these cells were not susceptible to invasion. We suggest that although eryptosis could be involved in malaria pathogenesis, it could also acting protectively by controlling parasite propagation.

Show MeSH
Related in: MedlinePlus