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Phytoecdysteroids as modulators of the Toxoplasma gondii growth rate in human and mouse cells.

Dzitko K, Grzybowski MM, Pawełczyk J, Dziadek B, Gatkowska J, Stączek P, Długońska H - Parasit Vectors (2015)

Bottom Line: Additionally, the tested phytoecdysteroids did not stimulate the in vitro secretion of the essential protective cytokines (IFN-γ, IL-2 and IL-10), neither by human nor by murine immune cells involved in an effective intracellular killing of the parasite.However, taking into account the possible stimulating effect of ecdysteroids on some opportunistic parasites (such as Toxoplasma or Strongyloides) further studies are necessary and should focus on the mechanisms of their action, which directly or indirectly enhance the parasite growth.Since ecdysteroids are considered as potential drugs, it is essential to determine their effect on various parasitic pathogens, which may infect the host at the same time, especially in immunocompromised individuals.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunoparasitology, Faculty of Biology and Environmental Protection, University of Łódź, Banacha 12/16, 90-237, Łódź, Poland. dzika@biol.uni.lodz.pl.

ABSTRACT

Background: Searching for new effective drugs against human and animal toxoplasmosis we decided to test the anti-Toxoplasma potential of phytoecdysteroids (α-ecdysone and 20-hydroxyecdysone) characterized by the pleiotropic activity on mammalian organisms including the enhancement of host's anti-parasitic defence. This objective was accomplished by the in vitro evaluation of T. gondii growth in phytoecdysteroid-treated immunocompetent cells of selected hosts: humans and two strains of inbred mice with genetically determined different susceptibility to toxoplasmosis.

Methods: Peripheral mononuclear blood cells were isolated from Toxoplasma-positive and Toxoplasma-negative women (N = 43) and men (N = 21). Non-infected mice (C57BL/6, N = 10 and BALB/c, N = 14) and mice (BALB/c, N = 10) challenged intraperitoneally with 5 tissue cysts of the T. gondii DX strain were also used in this study as a source of splenocytes. The effects of phytoecdysteroids on the viability of human PBMC and mouse splenocytes were evaluated using the MTT assay. The influence of phytoecdysteroids on PBMCs, splenocytes and T. gondii proliferation was measured using radioactivity tests (the level of 3[H] uracil incorporation by toxoplasms or 3[H] thymidine by PBMCs and splenocytes), which was confirmed by quantitative Real-Time PCR. Statistical analysis was performed using SigmaStat 3.5 (Systat Software GmbH). The best-fit IC50 curves were plotted using GraphPad Prism 6.0 (GraphPad Software, Inc.).

Results: Our results showed that phytoecdysteroids promote the multiplication of Toxoplasma in cultures of human or murine immune cells, in contrast to another apicomplexan parasite, Babesia gibsoni. Additionally, the tested phytoecdysteroids did not stimulate the in vitro secretion of the essential protective cytokines (IFN-γ, IL-2 and IL-10), neither by human nor by murine immune cells involved in an effective intracellular killing of the parasite.

Conclusions: Judging by the effect of phytoecdysteroids on the T. gondii proliferation, demonstrated for the first time in this study, it seems that these compounds should not be taken into consideration as potential medications to treat toxoplasmosis. Phytoecdysteroids included in the food are most likely not harmful for human or animal health but certain nutrients containing ecdysteroids at high concentrations could promote T. gondii proliferation in chronically infected and immunocompromised individuals. In order to assess the real impact of ecdysteroids on the course of natural T. gondii invasion, in vivo research should be undertaken because it cannot be ruled out that the in vivo effect will be different than the in vitro one. However, taking into account the possible stimulating effect of ecdysteroids on some opportunistic parasites (such as Toxoplasma or Strongyloides) further studies are necessary and should focus on the mechanisms of their action, which directly or indirectly enhance the parasite growth. Since ecdysteroids are considered as potential drugs, it is essential to determine their effect on various parasitic pathogens, which may infect the host at the same time, especially in immunocompromised individuals.

No MeSH data available.


Related in: MedlinePlus

Estimation of IC50 [μg/mL] values of sulfadiazine, pyrimethamine and hydroxyurea in T. gondii infected human PBMCs
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Fig2: Estimation of IC50 [μg/mL] values of sulfadiazine, pyrimethamine and hydroxyurea in T. gondii infected human PBMCs

Mentions: It was also found that the addition of concanavalin A to the tested cultures did not affect the final level of T. gondii proliferation; most likely because the host cells were unable to respond to a mitogen as quickly as the invasion of the parasites occurred. For comparative purposes we tested parallelly three different chemical agents able to restrict RH T. gondii growth: sulfadiazine and pirymethamine (used as recommended drugs in the therapy of toxoplasmosis) as well as hydroxyurea (used in anti-tumor therapy or in research) as a positive controls. In Fig. 2 we present the IC50 values for sulfadiazine (IC50 = 2495.91 μg/mL), pyrimethamine (IC50 = 14.69 μg/mL) and hydroxyurea (IC50 = 4.74 μg/mL) against RH T. gondii proliferating in normal human cells (PBMCs) at the parasite-host cell ratio of 2:1. Numerous studies proved that T. gondii susceptibility to a drug depends both on the invading strain and the host cells to be infected. Using the RH strain and different normal host cells, i.e., human MRC-5 [32], Vero [33], HFF [34] the IC50 values of sulfadiazine ranged from 2.5 to 77 μg/mL. In contrast to this, the use of human carcinoma HEp-2 [35] or HeLa [36] cells changed the IC50 to, 600–700 or >1000 μg/mL, respectively. As our observations reveal, the determination of the IC50 for a certain parasite strain is closely related to the type of host cells and also to the parasite load used.Fig. 2


Phytoecdysteroids as modulators of the Toxoplasma gondii growth rate in human and mouse cells.

Dzitko K, Grzybowski MM, Pawełczyk J, Dziadek B, Gatkowska J, Stączek P, Długońska H - Parasit Vectors (2015)

Estimation of IC50 [μg/mL] values of sulfadiazine, pyrimethamine and hydroxyurea in T. gondii infected human PBMCs
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4536731&req=5

Fig2: Estimation of IC50 [μg/mL] values of sulfadiazine, pyrimethamine and hydroxyurea in T. gondii infected human PBMCs
Mentions: It was also found that the addition of concanavalin A to the tested cultures did not affect the final level of T. gondii proliferation; most likely because the host cells were unable to respond to a mitogen as quickly as the invasion of the parasites occurred. For comparative purposes we tested parallelly three different chemical agents able to restrict RH T. gondii growth: sulfadiazine and pirymethamine (used as recommended drugs in the therapy of toxoplasmosis) as well as hydroxyurea (used in anti-tumor therapy or in research) as a positive controls. In Fig. 2 we present the IC50 values for sulfadiazine (IC50 = 2495.91 μg/mL), pyrimethamine (IC50 = 14.69 μg/mL) and hydroxyurea (IC50 = 4.74 μg/mL) against RH T. gondii proliferating in normal human cells (PBMCs) at the parasite-host cell ratio of 2:1. Numerous studies proved that T. gondii susceptibility to a drug depends both on the invading strain and the host cells to be infected. Using the RH strain and different normal host cells, i.e., human MRC-5 [32], Vero [33], HFF [34] the IC50 values of sulfadiazine ranged from 2.5 to 77 μg/mL. In contrast to this, the use of human carcinoma HEp-2 [35] or HeLa [36] cells changed the IC50 to, 600–700 or >1000 μg/mL, respectively. As our observations reveal, the determination of the IC50 for a certain parasite strain is closely related to the type of host cells and also to the parasite load used.Fig. 2

Bottom Line: Additionally, the tested phytoecdysteroids did not stimulate the in vitro secretion of the essential protective cytokines (IFN-γ, IL-2 and IL-10), neither by human nor by murine immune cells involved in an effective intracellular killing of the parasite.However, taking into account the possible stimulating effect of ecdysteroids on some opportunistic parasites (such as Toxoplasma or Strongyloides) further studies are necessary and should focus on the mechanisms of their action, which directly or indirectly enhance the parasite growth.Since ecdysteroids are considered as potential drugs, it is essential to determine their effect on various parasitic pathogens, which may infect the host at the same time, especially in immunocompromised individuals.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunoparasitology, Faculty of Biology and Environmental Protection, University of Łódź, Banacha 12/16, 90-237, Łódź, Poland. dzika@biol.uni.lodz.pl.

ABSTRACT

Background: Searching for new effective drugs against human and animal toxoplasmosis we decided to test the anti-Toxoplasma potential of phytoecdysteroids (α-ecdysone and 20-hydroxyecdysone) characterized by the pleiotropic activity on mammalian organisms including the enhancement of host's anti-parasitic defence. This objective was accomplished by the in vitro evaluation of T. gondii growth in phytoecdysteroid-treated immunocompetent cells of selected hosts: humans and two strains of inbred mice with genetically determined different susceptibility to toxoplasmosis.

Methods: Peripheral mononuclear blood cells were isolated from Toxoplasma-positive and Toxoplasma-negative women (N = 43) and men (N = 21). Non-infected mice (C57BL/6, N = 10 and BALB/c, N = 14) and mice (BALB/c, N = 10) challenged intraperitoneally with 5 tissue cysts of the T. gondii DX strain were also used in this study as a source of splenocytes. The effects of phytoecdysteroids on the viability of human PBMC and mouse splenocytes were evaluated using the MTT assay. The influence of phytoecdysteroids on PBMCs, splenocytes and T. gondii proliferation was measured using radioactivity tests (the level of 3[H] uracil incorporation by toxoplasms or 3[H] thymidine by PBMCs and splenocytes), which was confirmed by quantitative Real-Time PCR. Statistical analysis was performed using SigmaStat 3.5 (Systat Software GmbH). The best-fit IC50 curves were plotted using GraphPad Prism 6.0 (GraphPad Software, Inc.).

Results: Our results showed that phytoecdysteroids promote the multiplication of Toxoplasma in cultures of human or murine immune cells, in contrast to another apicomplexan parasite, Babesia gibsoni. Additionally, the tested phytoecdysteroids did not stimulate the in vitro secretion of the essential protective cytokines (IFN-γ, IL-2 and IL-10), neither by human nor by murine immune cells involved in an effective intracellular killing of the parasite.

Conclusions: Judging by the effect of phytoecdysteroids on the T. gondii proliferation, demonstrated for the first time in this study, it seems that these compounds should not be taken into consideration as potential medications to treat toxoplasmosis. Phytoecdysteroids included in the food are most likely not harmful for human or animal health but certain nutrients containing ecdysteroids at high concentrations could promote T. gondii proliferation in chronically infected and immunocompromised individuals. In order to assess the real impact of ecdysteroids on the course of natural T. gondii invasion, in vivo research should be undertaken because it cannot be ruled out that the in vivo effect will be different than the in vitro one. However, taking into account the possible stimulating effect of ecdysteroids on some opportunistic parasites (such as Toxoplasma or Strongyloides) further studies are necessary and should focus on the mechanisms of their action, which directly or indirectly enhance the parasite growth. Since ecdysteroids are considered as potential drugs, it is essential to determine their effect on various parasitic pathogens, which may infect the host at the same time, especially in immunocompromised individuals.

No MeSH data available.


Related in: MedlinePlus