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A parent-of-origin effect determines the susceptibility of a non-informative F1 population to Trypanosoma cruzi infection in vivo.

Silva GK, Cunha LD, Horta CV, Silva AL, Gutierrez FR, Silva JS, Zamboni DS - PLoS ONE (2013)

Bottom Line: The development of Chagas disease is determined by a complex interaction between the genetic traits of both the protozoan parasite, T. cruzi, and the infected host.This effect is unlikely to result from imprinted genes because the inheritance of this susceptibility was affected by the direction of the parental crossing.Future linkage studies may reveal the locus and genes participating on the host resistance process reported herein.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, University of São Paulo, Medical School Ribeirão Preto, FMRP/USP, Ribeirão Preto, São Paulo, Brazil.

ABSTRACT
The development of Chagas disease is determined by a complex interaction between the genetic traits of both the protozoan parasite, T. cruzi, and the infected host. This process is regulated by multiple genes that control different aspects of the host-parasite interaction. While determination of the relevant genes in humans is extremely difficult, it is feasible to use inbred mouse strains to determine the genes and loci responsible for host resistance to infection. In this study, we investigated the susceptibility of several inbred mouse strains to infection with the highly virulent Y strain of T. cruzi and found a considerable difference in susceptibility between A/J and C57BL/6 mice. We explored the differences between these two mouse strains and found that the A/J strain presented higher mortality, exacerbated and uncontrolled parasitemia and distinct histopathology in the target organs, which were associated with a higher parasite burden and more extensive tissue lesions. We then employed a genetic approach to assess the pattern of inheritance of the resistance phenotype in an F1 population and detected a strong parent-of-origin effect determining the susceptibility of the F1 male mice. This effect is unlikely to result from imprinted genes because the inheritance of this susceptibility was affected by the direction of the parental crossing. Collectively, our genetic approach of using the F1 population suggests that genes contained in the murine chromosome X contribute to the natural resistance against T. cruzi infection. Future linkage studies may reveal the locus and genes participating on the host resistance process reported herein.

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Macrophages from A/J mice are more susceptible to T. cruzi infection than those from C57BL/6 mice.Bone marrow-derived macrophages (BMDMs) from A/J and C57BL/6 mice were infected at a multiplicity of infection of 5 with trypomastigotes of the Y strain of T. cruzi. At 48 h postinfection, cells were fixed and stained with Giemsa. (A) Representative micrographs of infected cells. Arrows indicate the intracellular amastigotes; arrowheads indicate the macrophage nuclei. The scale bar represents 20 µm. (B) Percentage of parasite-infected BMDMs containing 1 to 3, 4 to 6, 7 to 9, 10 to 15, or >15 amastigotes per cell. A total of 100 infected cells were scored in each of the 6 distinguished replicates. Data are expressed as the mean ± standard deviation of the 6 replicates. The experiment shown is representative of those found in three independent experiments. (*) indicates P<0.05.
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pone-0056347-g002: Macrophages from A/J mice are more susceptible to T. cruzi infection than those from C57BL/6 mice.Bone marrow-derived macrophages (BMDMs) from A/J and C57BL/6 mice were infected at a multiplicity of infection of 5 with trypomastigotes of the Y strain of T. cruzi. At 48 h postinfection, cells were fixed and stained with Giemsa. (A) Representative micrographs of infected cells. Arrows indicate the intracellular amastigotes; arrowheads indicate the macrophage nuclei. The scale bar represents 20 µm. (B) Percentage of parasite-infected BMDMs containing 1 to 3, 4 to 6, 7 to 9, 10 to 15, or >15 amastigotes per cell. A total of 100 infected cells were scored in each of the 6 distinguished replicates. Data are expressed as the mean ± standard deviation of the 6 replicates. The experiment shown is representative of those found in three independent experiments. (*) indicates P<0.05.

Mentions: The early manifestations of T. cruzi infection in humans and in experimental models of infection support an important role of innate immunity for successfully controlling the initial replication of the parasites. Macrophages are an important host cell for the outcome of T. cruzi infection; therefore, strain differences in the capacity to control the initial phase of infection could involve differences in the capacity of these cells to restrict the multiplication of the parasites. To verify whether genetic differences between the C57BL/6 and A/J strains influence the effectiveness of their innate immune responses to T. cruzi, we evaluated parasite multiplication in BMDMs obtained from these two mouse strains. The BMDMs obtained from the A/J and C57BL/6 mice were infected with the trypomastigote form of T. cruzi at an MOI of 5. After infection for 48 h, the intracellular amastigotes were stained and their quantity microscopically scored. We found that the number of amastigote parasites within the cytoplasm of the infected BMDMs differed greatly between these two mouse strains (Fig. 2A). The A/J-derived BMDMs contained higher parasite loads, with an average of 10.1±1.2 amastigotes per cell. In contrast, the BMDMs from the C57BL/6 mice averaged only 5.8±0.8 amastigotes per cell. The internalization of the trypomastigote form of T. cruzi by the BMDMs from these two mice strains was similar, as assessed by estimating the number of intracellular parasites after infection for 4 h (data not shown). Therefore, the data shown in Fig. 2 suggest that intrinsic genetic differences between these two strains play a role in their ability to restrict the intracellular replication of T. cruzi.


A parent-of-origin effect determines the susceptibility of a non-informative F1 population to Trypanosoma cruzi infection in vivo.

Silva GK, Cunha LD, Horta CV, Silva AL, Gutierrez FR, Silva JS, Zamboni DS - PLoS ONE (2013)

Macrophages from A/J mice are more susceptible to T. cruzi infection than those from C57BL/6 mice.Bone marrow-derived macrophages (BMDMs) from A/J and C57BL/6 mice were infected at a multiplicity of infection of 5 with trypomastigotes of the Y strain of T. cruzi. At 48 h postinfection, cells were fixed and stained with Giemsa. (A) Representative micrographs of infected cells. Arrows indicate the intracellular amastigotes; arrowheads indicate the macrophage nuclei. The scale bar represents 20 µm. (B) Percentage of parasite-infected BMDMs containing 1 to 3, 4 to 6, 7 to 9, 10 to 15, or >15 amastigotes per cell. A total of 100 infected cells were scored in each of the 6 distinguished replicates. Data are expressed as the mean ± standard deviation of the 6 replicates. The experiment shown is representative of those found in three independent experiments. (*) indicates P<0.05.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3569416&req=5

pone-0056347-g002: Macrophages from A/J mice are more susceptible to T. cruzi infection than those from C57BL/6 mice.Bone marrow-derived macrophages (BMDMs) from A/J and C57BL/6 mice were infected at a multiplicity of infection of 5 with trypomastigotes of the Y strain of T. cruzi. At 48 h postinfection, cells were fixed and stained with Giemsa. (A) Representative micrographs of infected cells. Arrows indicate the intracellular amastigotes; arrowheads indicate the macrophage nuclei. The scale bar represents 20 µm. (B) Percentage of parasite-infected BMDMs containing 1 to 3, 4 to 6, 7 to 9, 10 to 15, or >15 amastigotes per cell. A total of 100 infected cells were scored in each of the 6 distinguished replicates. Data are expressed as the mean ± standard deviation of the 6 replicates. The experiment shown is representative of those found in three independent experiments. (*) indicates P<0.05.
Mentions: The early manifestations of T. cruzi infection in humans and in experimental models of infection support an important role of innate immunity for successfully controlling the initial replication of the parasites. Macrophages are an important host cell for the outcome of T. cruzi infection; therefore, strain differences in the capacity to control the initial phase of infection could involve differences in the capacity of these cells to restrict the multiplication of the parasites. To verify whether genetic differences between the C57BL/6 and A/J strains influence the effectiveness of their innate immune responses to T. cruzi, we evaluated parasite multiplication in BMDMs obtained from these two mouse strains. The BMDMs obtained from the A/J and C57BL/6 mice were infected with the trypomastigote form of T. cruzi at an MOI of 5. After infection for 48 h, the intracellular amastigotes were stained and their quantity microscopically scored. We found that the number of amastigote parasites within the cytoplasm of the infected BMDMs differed greatly between these two mouse strains (Fig. 2A). The A/J-derived BMDMs contained higher parasite loads, with an average of 10.1±1.2 amastigotes per cell. In contrast, the BMDMs from the C57BL/6 mice averaged only 5.8±0.8 amastigotes per cell. The internalization of the trypomastigote form of T. cruzi by the BMDMs from these two mice strains was similar, as assessed by estimating the number of intracellular parasites after infection for 4 h (data not shown). Therefore, the data shown in Fig. 2 suggest that intrinsic genetic differences between these two strains play a role in their ability to restrict the intracellular replication of T. cruzi.

Bottom Line: The development of Chagas disease is determined by a complex interaction between the genetic traits of both the protozoan parasite, T. cruzi, and the infected host.This effect is unlikely to result from imprinted genes because the inheritance of this susceptibility was affected by the direction of the parental crossing.Future linkage studies may reveal the locus and genes participating on the host resistance process reported herein.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, University of São Paulo, Medical School Ribeirão Preto, FMRP/USP, Ribeirão Preto, São Paulo, Brazil.

ABSTRACT
The development of Chagas disease is determined by a complex interaction between the genetic traits of both the protozoan parasite, T. cruzi, and the infected host. This process is regulated by multiple genes that control different aspects of the host-parasite interaction. While determination of the relevant genes in humans is extremely difficult, it is feasible to use inbred mouse strains to determine the genes and loci responsible for host resistance to infection. In this study, we investigated the susceptibility of several inbred mouse strains to infection with the highly virulent Y strain of T. cruzi and found a considerable difference in susceptibility between A/J and C57BL/6 mice. We explored the differences between these two mouse strains and found that the A/J strain presented higher mortality, exacerbated and uncontrolled parasitemia and distinct histopathology in the target organs, which were associated with a higher parasite burden and more extensive tissue lesions. We then employed a genetic approach to assess the pattern of inheritance of the resistance phenotype in an F1 population and detected a strong parent-of-origin effect determining the susceptibility of the F1 male mice. This effect is unlikely to result from imprinted genes because the inheritance of this susceptibility was affected by the direction of the parental crossing. Collectively, our genetic approach of using the F1 population suggests that genes contained in the murine chromosome X contribute to the natural resistance against T. cruzi infection. Future linkage studies may reveal the locus and genes participating on the host resistance process reported herein.

Show MeSH
Related in: MedlinePlus