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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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C57BL/6 and A/J mice infected with T. cruzi differ in cardiac and hepatic histopathology, tissue injury and parasite load.A/J and C57BL/6 mice were infected i.p. with 1000 trypomastigotes of the Y strain of T. cruzi. Infected animals were euthanized 15 days postinfection, and cardiac muscle and liver were collected and processed as described in Material and Methods. (A) Tissue samples were stained with hematoxylin-eosin to determine the presence of inflammatory infiltrates. Representative micrographs of C57BL/6 and A/J tissues are shown. Arrows indicate the presence of infiltrates of mononuclear cells in the myocardium and among the hepatocytes; the scale bar represents 100 µm. (B–C) Inflammatory infiltrates in the heart (B) and liver (C) were determined by counting nuclei of infiltrating cells after staining the organ sections with hematoxylin-eosin. (D–E) Lesions in the heart (D) and liver (E) of infected mice were estimated by quantifying the levels of creatine kinase enzyme (CK-MB) and alanine transaminase (ALT), respectively. (F–G) Parasite loads in the heart (F) and liver (G) of infected mice were determined by quantitative real time PCR using specific primers for T. cruzi (as described in Material and Methods). Data are representative of those found in three independent experiments. (*) indicates P<0.05.
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pone-0056347-g003: C57BL/6 and A/J mice infected with T. cruzi differ in cardiac and hepatic histopathology, tissue injury and parasite load.A/J and C57BL/6 mice were infected i.p. with 1000 trypomastigotes of the Y strain of T. cruzi. Infected animals were euthanized 15 days postinfection, and cardiac muscle and liver were collected and processed as described in Material and Methods. (A) Tissue samples were stained with hematoxylin-eosin to determine the presence of inflammatory infiltrates. Representative micrographs of C57BL/6 and A/J tissues are shown. Arrows indicate the presence of infiltrates of mononuclear cells in the myocardium and among the hepatocytes; the scale bar represents 100 µm. (B–C) Inflammatory infiltrates in the heart (B) and liver (C) were determined by counting nuclei of infiltrating cells after staining the organ sections with hematoxylin-eosin. (D–E) Lesions in the heart (D) and liver (E) of infected mice were estimated by quantifying the levels of creatine kinase enzyme (CK-MB) and alanine transaminase (ALT), respectively. (F–G) Parasite loads in the heart (F) and liver (G) of infected mice were determined by quantitative real time PCR using specific primers for T. cruzi (as described in Material and Methods). Data are representative of those found in three independent experiments. (*) indicates P<0.05.

Mentions: Variability in the pattern of tissue invasion by T. cruzi parasites in infected individuals is often observed in Chagas disease. Likewise, previous reports showed that genetic variation between mice strains was influenced by tissue tropism in chronic models of experimental infection by a single strain of T. cruzi[30]. Because our initial data indicated much variation among mouse strains in the parasitemia induced by T. cruzi, we investigated the replication of the parasite, the inflammatory response and the extent of the tissue damage in the hearts and livers of the infected mice. Examination of the tissue sections 15 days postinfection revealed distinct patterns of inflammatory infiltration between the A/J and C57BL/6 mice. As observed in Fig. 3A, the hearts of the infected C57BL/6 mice were more highly infiltrated by inflammatory cells than were those of the infected A/J mice. By contrast, the hepatic tissue of the A/J mice showed a higher inflammatory infiltrate than did that of the C57BL/6 mice (Fig. 3A). These phenotypes were further confirmed by quantifying the number of cells in the inflammatory infiltrate in these organs (Fig. 3B, C). To evaluate the extent of the tissue damage, we quantified the activity of the serological enzymatic markers of tissue injury: cardiac creatine kinase (CK-MB) and hepatic alanine aminotransferase (ALT). Our data showed that the CK-MB and ALT activities were higher in the tissue samples from the A/J mice compared with the C57BL/6 mice (Fig. 3D, E). Importantly, the accurate estimation of the extent of the organ lesions by the organ-specific enzyme activity analysis suggests that the A/J mice suffered worse damage to both organs despite their reduced cardiac inflammatory infiltrate. These findings support the hypothesis that the cardiac lesion induced by T. cruzi more likely resulted from tissue destruction induced by parasite replication than from damage triggered by the inflammatory infiltrate itself. Importantly, the reduced cardiac inflammatory response of the A/J mice coincided with a higher cardiac burden of T. cruzi than was observed in the C57BL/6 mice (Fig. 3F). We also observed a tendency for a higher hepatic parasite burden in the infected A/J mice compared with their C57BL/6 counterparts (Fig. 3G). Collectively, these data indicate that the C57BL/6 mice differ from the A/J mice not only in resistance to lethal infection and parasitemia, but also in tissue lesion, inflammatory response and parasite burden in the organs. These features support further investigation of these two inbred mouse strains to determine the genetic basis for the immune response that leads to resistance to infection.


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)

C57BL/6 and A/J mice infected with T. cruzi differ in cardiac and hepatic histopathology, tissue injury and parasite load.A/J and C57BL/6 mice were infected i.p. with 1000 trypomastigotes of the Y strain of T. cruzi. Infected animals were euthanized 15 days postinfection, and cardiac muscle and liver were collected and processed as described in Material and Methods. (A) Tissue samples were stained with hematoxylin-eosin to determine the presence of inflammatory infiltrates. Representative micrographs of C57BL/6 and A/J tissues are shown. Arrows indicate the presence of infiltrates of mononuclear cells in the myocardium and among the hepatocytes; the scale bar represents 100 µm. (B–C) Inflammatory infiltrates in the heart (B) and liver (C) were determined by counting nuclei of infiltrating cells after staining the organ sections with hematoxylin-eosin. (D–E) Lesions in the heart (D) and liver (E) of infected mice were estimated by quantifying the levels of creatine kinase enzyme (CK-MB) and alanine transaminase (ALT), respectively. (F–G) Parasite loads in the heart (F) and liver (G) of infected mice were determined by quantitative real time PCR using specific primers for T. cruzi (as described in Material and Methods). Data are representative of those found in three independent experiments. (*) indicates P<0.05.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3569416&req=5

pone-0056347-g003: C57BL/6 and A/J mice infected with T. cruzi differ in cardiac and hepatic histopathology, tissue injury and parasite load.A/J and C57BL/6 mice were infected i.p. with 1000 trypomastigotes of the Y strain of T. cruzi. Infected animals were euthanized 15 days postinfection, and cardiac muscle and liver were collected and processed as described in Material and Methods. (A) Tissue samples were stained with hematoxylin-eosin to determine the presence of inflammatory infiltrates. Representative micrographs of C57BL/6 and A/J tissues are shown. Arrows indicate the presence of infiltrates of mononuclear cells in the myocardium and among the hepatocytes; the scale bar represents 100 µm. (B–C) Inflammatory infiltrates in the heart (B) and liver (C) were determined by counting nuclei of infiltrating cells after staining the organ sections with hematoxylin-eosin. (D–E) Lesions in the heart (D) and liver (E) of infected mice were estimated by quantifying the levels of creatine kinase enzyme (CK-MB) and alanine transaminase (ALT), respectively. (F–G) Parasite loads in the heart (F) and liver (G) of infected mice were determined by quantitative real time PCR using specific primers for T. cruzi (as described in Material and Methods). Data are representative of those found in three independent experiments. (*) indicates P<0.05.
Mentions: Variability in the pattern of tissue invasion by T. cruzi parasites in infected individuals is often observed in Chagas disease. Likewise, previous reports showed that genetic variation between mice strains was influenced by tissue tropism in chronic models of experimental infection by a single strain of T. cruzi[30]. Because our initial data indicated much variation among mouse strains in the parasitemia induced by T. cruzi, we investigated the replication of the parasite, the inflammatory response and the extent of the tissue damage in the hearts and livers of the infected mice. Examination of the tissue sections 15 days postinfection revealed distinct patterns of inflammatory infiltration between the A/J and C57BL/6 mice. As observed in Fig. 3A, the hearts of the infected C57BL/6 mice were more highly infiltrated by inflammatory cells than were those of the infected A/J mice. By contrast, the hepatic tissue of the A/J mice showed a higher inflammatory infiltrate than did that of the C57BL/6 mice (Fig. 3A). These phenotypes were further confirmed by quantifying the number of cells in the inflammatory infiltrate in these organs (Fig. 3B, C). To evaluate the extent of the tissue damage, we quantified the activity of the serological enzymatic markers of tissue injury: cardiac creatine kinase (CK-MB) and hepatic alanine aminotransferase (ALT). Our data showed that the CK-MB and ALT activities were higher in the tissue samples from the A/J mice compared with the C57BL/6 mice (Fig. 3D, E). Importantly, the accurate estimation of the extent of the organ lesions by the organ-specific enzyme activity analysis suggests that the A/J mice suffered worse damage to both organs despite their reduced cardiac inflammatory infiltrate. These findings support the hypothesis that the cardiac lesion induced by T. cruzi more likely resulted from tissue destruction induced by parasite replication than from damage triggered by the inflammatory infiltrate itself. Importantly, the reduced cardiac inflammatory response of the A/J mice coincided with a higher cardiac burden of T. cruzi than was observed in the C57BL/6 mice (Fig. 3F). We also observed a tendency for a higher hepatic parasite burden in the infected A/J mice compared with their C57BL/6 counterparts (Fig. 3G). Collectively, these data indicate that the C57BL/6 mice differ from the A/J mice not only in resistance to lethal infection and parasitemia, but also in tissue lesion, inflammatory response and parasite burden in the organs. These features support further investigation of these two inbred mouse strains to determine the genetic basis for the immune response that leads to resistance to infection.

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