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A sufficient role of MHC class I molecules on hepatocytes in anti-plasmodial activity of CD8 (+) T cells in vivo.

Huang J, Tsao T, Zhang M, Rai U, Tsuji M, Li X - Front Microbiol (2015)

Bottom Line: Presently, there is only one CD8(+) epitope, SYVPSAEQI, derived from the circumsporozoite protein of Plasmodium yoelii (PyCS), that mediates anti-malarial protection and is presented in the context of a K(d) molecule.We found that the adoptive transfer of a PyCS-specific CD8(+) T-cell line resulted in a significant inhibition of the parasite burden in the liver of Alb-K(d) Tg, as well as MHC-I-K(d) Tg mice, but not of C57BL/6 mice.These results indicate that the K(d) molecule expressed by hepatocytes is sufficient in mediating the anti-plasmodial activity of PyCS-specific CD8(+) T cells in vivo.

View Article: PubMed Central - PubMed

Affiliation: HIV and Malaria Vaccine Program, Aaron Diamond AIDS Research Center - The Rockefeller University New York, NY, USA.

ABSTRACT
Although CD8(+) T cells are shown to mediate the protective immunity against the liver stages of malaria parasites in mice, whether the direct presentation of malaria antigen by major histocompatibility complex (MHC) class I molecules expressed on the liver of infected host is required for anti-plasmodial activity of CD8(+) T cells is still unknown. Presently, there is only one CD8(+) epitope, SYVPSAEQI, derived from the circumsporozoite protein of Plasmodium yoelii (PyCS), that mediates anti-malarial protection and is presented in the context of a K(d) molecule. Therefore, to investigate the mode of anti-plasmodial activity of CD8+ T cells, we have previously generated C57BL/6 transgenic (Tg) mice, in which a K(d) molecule is expressed only on hepatocyte (Alb-K(d)) or dendritic cell (DC; CD11c-K(d)), by using albumin promoter or CD11c promoter, respectively. We have also generated MHC-I-K(d) Tg mice, which express the K(d) molecule under the MHC class I (MHC-I) promoter, as a positive control. From splenocytes collected from CD11c-K(d) Tg mice immunized with a synthetic peptide, SYVPSAEQI, which corresponds to the CD8(+) T-cell epitope of PyCS, emulsified in incomplete Freund's adjuvant , a PyCS-specific CD8(+) T-cell line was generated. This PyCS-specific CD8(+)T-cell line was then adoptively transferred into a cohort of either MHC-K(d) Tg or Alb-K(d) Tg mice listed above, as well as wild-type C57BL/6 mice. Then both transferred and non-transferred mice were challenged with live malaria parasites. We found that the adoptive transfer of a PyCS-specific CD8(+) T-cell line resulted in a significant inhibition of the parasite burden in the liver of Alb-K(d) Tg, as well as MHC-I-K(d) Tg mice, but not of C57BL/6 mice. These results indicate that the K(d) molecule expressed by hepatocytes is sufficient in mediating the anti-plasmodial activity of PyCS-specific CD8(+) T cells in vivo.

No MeSH data available.


Related in: MedlinePlus

Inhibition of Plasmodium yoeli liver stage development in MHC-Kd mice and Alb-Kd mice upon adoptive transfer of PyCS-specific CD8+ T cells, as determined by a real-time qRT-PCR. Each mouse of MHC-Kd Tg mice, Alb-Kd Tg mice, and wild-type C57BL/6J mice (three mice per group) received 1 × 107cells of a PyCS-specific CD8+ T-cell line intravenously. Twenty-four hours later, the transferred, as well as non-transferred Tg mice and wild-type C57BL/6 mice, were challenged by 1 × 104 viable P. yoelii sporozoites. After 42 h, the parasite burden in the liver was determined by measuring the relative copy number of parasite-specific 18S rRNA to that of mouse GAPDH using a real-time qRT-PCR. The mice that do not receive PyCS-specific CD8+ T-cell transfer served as negative controls. Error bars represent means ± SEM (n = 3). A value of p < 0.05 was considered statistically significant, whereas N.S. means “not significant.”
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Figure 2: Inhibition of Plasmodium yoeli liver stage development in MHC-Kd mice and Alb-Kd mice upon adoptive transfer of PyCS-specific CD8+ T cells, as determined by a real-time qRT-PCR. Each mouse of MHC-Kd Tg mice, Alb-Kd Tg mice, and wild-type C57BL/6J mice (three mice per group) received 1 × 107cells of a PyCS-specific CD8+ T-cell line intravenously. Twenty-four hours later, the transferred, as well as non-transferred Tg mice and wild-type C57BL/6 mice, were challenged by 1 × 104 viable P. yoelii sporozoites. After 42 h, the parasite burden in the liver was determined by measuring the relative copy number of parasite-specific 18S rRNA to that of mouse GAPDH using a real-time qRT-PCR. The mice that do not receive PyCS-specific CD8+ T-cell transfer served as negative controls. Error bars represent means ± SEM (n = 3). A value of p < 0.05 was considered statistically significant, whereas N.S. means “not significant.”

Mentions: Now that we generated a PyCS-specific CD8+ T-cell line having more than two third of the cells specific to SYVPSAEQI peptide, we sought to address one of the key questions regarding the manner in which CD8+ T cells recognize and eliminate the hepatic stage of malaria in vivo. More specifically, we aimed to determine the role of MHC-I molecules expressed on hepatocytes in mediating CD8+ T cells’ recognition of malaria-infected hepatocytes and their anti-plasmodial activity in vivo. For this purpose, we adoptively transferred 1 × 107 cells of PyCS-specific CD8+ T-cell line to three groups (three mice each): MHC-I-Kd Tg mice (as a positive control), Alb-Kd Tg mice and wild-type C57BL/6 mice (as a negative control). Respective Tg mice that do not receive the PyCS-specific CD8+ T-cell transfer were used as a negative control for each group of transferred Tg mice. All experimental mice were then challenged with 1 × 104 live P. yoelii sporozoites. Forty-two hours after the challenge, the livers were collected from challenged mice, and the liver parasite burden was determined by measuring the parasite-specific rRNA by real-time PCR and quantified by a ratio of the absolute copy number of parasite-specific 18S rRNA to that of mouse GAPDH. After the P. yoelii sporozoites challenge, the PyCS-specific CD8+ T-cell line inhibited almost 50% of the parasite burden in the liver of MHC-I-Kd Tg mice, but not in C57BL/6 mice (Figure 2). Most importantly, a PyCS-specific CD8+ T-cell line transferred to Alb-Kd Tg mice could inhibit (55%) the liver stage development as potently as those transferred to MHC-I-Kd Tg mice. These results indicate that Kd molecules expressed on hepatocytes are sufficient in mediating the anti-parasitic effect of PyCS-specific CD8+ T cells in vivo.


A sufficient role of MHC class I molecules on hepatocytes in anti-plasmodial activity of CD8 (+) T cells in vivo.

Huang J, Tsao T, Zhang M, Rai U, Tsuji M, Li X - Front Microbiol (2015)

Inhibition of Plasmodium yoeli liver stage development in MHC-Kd mice and Alb-Kd mice upon adoptive transfer of PyCS-specific CD8+ T cells, as determined by a real-time qRT-PCR. Each mouse of MHC-Kd Tg mice, Alb-Kd Tg mice, and wild-type C57BL/6J mice (three mice per group) received 1 × 107cells of a PyCS-specific CD8+ T-cell line intravenously. Twenty-four hours later, the transferred, as well as non-transferred Tg mice and wild-type C57BL/6 mice, were challenged by 1 × 104 viable P. yoelii sporozoites. After 42 h, the parasite burden in the liver was determined by measuring the relative copy number of parasite-specific 18S rRNA to that of mouse GAPDH using a real-time qRT-PCR. The mice that do not receive PyCS-specific CD8+ T-cell transfer served as negative controls. Error bars represent means ± SEM (n = 3). A value of p < 0.05 was considered statistically significant, whereas N.S. means “not significant.”
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Related In: Results  -  Collection

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Figure 2: Inhibition of Plasmodium yoeli liver stage development in MHC-Kd mice and Alb-Kd mice upon adoptive transfer of PyCS-specific CD8+ T cells, as determined by a real-time qRT-PCR. Each mouse of MHC-Kd Tg mice, Alb-Kd Tg mice, and wild-type C57BL/6J mice (three mice per group) received 1 × 107cells of a PyCS-specific CD8+ T-cell line intravenously. Twenty-four hours later, the transferred, as well as non-transferred Tg mice and wild-type C57BL/6 mice, were challenged by 1 × 104 viable P. yoelii sporozoites. After 42 h, the parasite burden in the liver was determined by measuring the relative copy number of parasite-specific 18S rRNA to that of mouse GAPDH using a real-time qRT-PCR. The mice that do not receive PyCS-specific CD8+ T-cell transfer served as negative controls. Error bars represent means ± SEM (n = 3). A value of p < 0.05 was considered statistically significant, whereas N.S. means “not significant.”
Mentions: Now that we generated a PyCS-specific CD8+ T-cell line having more than two third of the cells specific to SYVPSAEQI peptide, we sought to address one of the key questions regarding the manner in which CD8+ T cells recognize and eliminate the hepatic stage of malaria in vivo. More specifically, we aimed to determine the role of MHC-I molecules expressed on hepatocytes in mediating CD8+ T cells’ recognition of malaria-infected hepatocytes and their anti-plasmodial activity in vivo. For this purpose, we adoptively transferred 1 × 107 cells of PyCS-specific CD8+ T-cell line to three groups (three mice each): MHC-I-Kd Tg mice (as a positive control), Alb-Kd Tg mice and wild-type C57BL/6 mice (as a negative control). Respective Tg mice that do not receive the PyCS-specific CD8+ T-cell transfer were used as a negative control for each group of transferred Tg mice. All experimental mice were then challenged with 1 × 104 live P. yoelii sporozoites. Forty-two hours after the challenge, the livers were collected from challenged mice, and the liver parasite burden was determined by measuring the parasite-specific rRNA by real-time PCR and quantified by a ratio of the absolute copy number of parasite-specific 18S rRNA to that of mouse GAPDH. After the P. yoelii sporozoites challenge, the PyCS-specific CD8+ T-cell line inhibited almost 50% of the parasite burden in the liver of MHC-I-Kd Tg mice, but not in C57BL/6 mice (Figure 2). Most importantly, a PyCS-specific CD8+ T-cell line transferred to Alb-Kd Tg mice could inhibit (55%) the liver stage development as potently as those transferred to MHC-I-Kd Tg mice. These results indicate that Kd molecules expressed on hepatocytes are sufficient in mediating the anti-parasitic effect of PyCS-specific CD8+ T cells in vivo.

Bottom Line: Presently, there is only one CD8(+) epitope, SYVPSAEQI, derived from the circumsporozoite protein of Plasmodium yoelii (PyCS), that mediates anti-malarial protection and is presented in the context of a K(d) molecule.We found that the adoptive transfer of a PyCS-specific CD8(+) T-cell line resulted in a significant inhibition of the parasite burden in the liver of Alb-K(d) Tg, as well as MHC-I-K(d) Tg mice, but not of C57BL/6 mice.These results indicate that the K(d) molecule expressed by hepatocytes is sufficient in mediating the anti-plasmodial activity of PyCS-specific CD8(+) T cells in vivo.

View Article: PubMed Central - PubMed

Affiliation: HIV and Malaria Vaccine Program, Aaron Diamond AIDS Research Center - The Rockefeller University New York, NY, USA.

ABSTRACT
Although CD8(+) T cells are shown to mediate the protective immunity against the liver stages of malaria parasites in mice, whether the direct presentation of malaria antigen by major histocompatibility complex (MHC) class I molecules expressed on the liver of infected host is required for anti-plasmodial activity of CD8(+) T cells is still unknown. Presently, there is only one CD8(+) epitope, SYVPSAEQI, derived from the circumsporozoite protein of Plasmodium yoelii (PyCS), that mediates anti-malarial protection and is presented in the context of a K(d) molecule. Therefore, to investigate the mode of anti-plasmodial activity of CD8+ T cells, we have previously generated C57BL/6 transgenic (Tg) mice, in which a K(d) molecule is expressed only on hepatocyte (Alb-K(d)) or dendritic cell (DC; CD11c-K(d)), by using albumin promoter or CD11c promoter, respectively. We have also generated MHC-I-K(d) Tg mice, which express the K(d) molecule under the MHC class I (MHC-I) promoter, as a positive control. From splenocytes collected from CD11c-K(d) Tg mice immunized with a synthetic peptide, SYVPSAEQI, which corresponds to the CD8(+) T-cell epitope of PyCS, emulsified in incomplete Freund's adjuvant , a PyCS-specific CD8(+) T-cell line was generated. This PyCS-specific CD8(+)T-cell line was then adoptively transferred into a cohort of either MHC-K(d) Tg or Alb-K(d) Tg mice listed above, as well as wild-type C57BL/6 mice. Then both transferred and non-transferred mice were challenged with live malaria parasites. We found that the adoptive transfer of a PyCS-specific CD8(+) T-cell line resulted in a significant inhibition of the parasite burden in the liver of Alb-K(d) Tg, as well as MHC-I-K(d) Tg mice, but not of C57BL/6 mice. These results indicate that the K(d) molecule expressed by hepatocytes is sufficient in mediating the anti-plasmodial activity of PyCS-specific CD8(+) T cells in vivo.

No MeSH data available.


Related in: MedlinePlus