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Hypergravity Provokes a Temporary Reduction in CD4+CD8+ Thymocyte Number and a Persistent Decrease in Medullary Thymic Epithelial Cell Frequency in Mice.

Tateishi R, Akiyama N, Miyauchi M, Yoshinaga R, Sasanuma H, Kudo T, Shimbo M, Shinohara M, Obata K, Inoue J, Shirakawa M, Shiba D, Asahara H, Yoshida N, Takahashi S, Morita H, Akiyama T - PLoS ONE (2015)

Bottom Line: We investigated the effects of hypergravity (2G) on murine thymic cells.Interestingly, a surgical lesion of the inner ear's vestibular apparatus inhibited these hypergravity effects.Overall, data suggest that 2G causes a temporary reduction of DP and a persistent reduction of mature mTECs in a vestibular system-dependent manner, and also dysregulates mTEC gene expression without involving the vestibular system.

View Article: PubMed Central - PubMed

Affiliation: Division of Cellular and Molecular Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan; Mouse epigenetics project, ISS/Kibo experiment, Japan Aerospace Exploration Agency, JAXA, Tsukuba, Japan.

ABSTRACT
Gravity change affects many immunological systems. We investigated the effects of hypergravity (2G) on murine thymic cells. Exposure of mice to 2G for three days reduced the frequency of CD4+CD8+ thymocytes (DP) and mature medullary thymic epithelial cells (mTECs), accompanied by an increment of keratin-5 and keratin-8 double-positive (K5+K8+) TECs that reportedly contain TEC progenitors. Whereas the reduction of DP was recovered by a 14-day exposure to 2G, the reduction of mature mTECs and the increment of K5+K8+ TEC persisted. Interestingly, a surgical lesion of the inner ear's vestibular apparatus inhibited these hypergravity effects. Quantitative PCR analysis revealed that the gene expression of Aire and RANK that are critical for mTEC function and development were up-regulated by the 3-day exposure and subsequently down-regulated by the 14-day exposure to 2G. Unexpectedly, this dynamic change in mTEC gene expression was independent of the vestibular apparatus. Overall, data suggest that 2G causes a temporary reduction of DP and a persistent reduction of mature mTECs in a vestibular system-dependent manner, and also dysregulates mTEC gene expression without involving the vestibular system. These data might provide insight on the impact of gravity change on thymic functions during spaceflight and living.

No MeSH data available.


Related in: MedlinePlus

The short-term hypergravity exposure causes a reduction of CD4+CD8+ double positive thymocytes in a vestibular apparatus-dependent manner.(A) Ratio of thymic weight to body weight (left) and total thymic cell number (right) of mice exposed to 2 g gravity (labeled as 2G) for 3 day or normal gravity control (labeled as C). Vestibular apparatus were surgically disrupted in some groups of mice (labeled as VL). N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and **P < 0.01 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (B) Flow cytometric analysis of thymocytes in mice exposed to 2G for 3 days. Thymocytes were analyzed by staining with CD4 and CD8α antibodies (left figures). Numbers in panels indicates percentage of each fraction. Percentages of CD4- and CD8-double positive thymocytes (CD4+CD8+DP) in total thymocytes are summarized in right figures. Mice were exposed to 2 g gravity (2G) for 3 days. “C” indicates 1G control. Vestibular apparatus are surgically disrupted in some groups of mice (VL). N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (C) Cell numbers of CD4+CD8+ (CD4+CD8+DP), CD4+CD8- (CD4SP), CD4-CD8+ (CD8SP), and CD4-CD8- (DN) fractions in mice exposed to 2G for 3days. N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test).
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pone.0141650.g001: The short-term hypergravity exposure causes a reduction of CD4+CD8+ double positive thymocytes in a vestibular apparatus-dependent manner.(A) Ratio of thymic weight to body weight (left) and total thymic cell number (right) of mice exposed to 2 g gravity (labeled as 2G) for 3 day or normal gravity control (labeled as C). Vestibular apparatus were surgically disrupted in some groups of mice (labeled as VL). N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and **P < 0.01 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (B) Flow cytometric analysis of thymocytes in mice exposed to 2G for 3 days. Thymocytes were analyzed by staining with CD4 and CD8α antibodies (left figures). Numbers in panels indicates percentage of each fraction. Percentages of CD4- and CD8-double positive thymocytes (CD4+CD8+DP) in total thymocytes are summarized in right figures. Mice were exposed to 2 g gravity (2G) for 3 days. “C” indicates 1G control. Vestibular apparatus are surgically disrupted in some groups of mice (VL). N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (C) Cell numbers of CD4+CD8+ (CD4+CD8+DP), CD4+CD8- (CD4SP), CD4-CD8+ (CD8SP), and CD4-CD8- (DN) fractions in mice exposed to 2G for 3days. N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test).

Mentions: Mice were exposed to 2G by chronic centrifugation. Exposure to 2G for 3 days significantly resulted in a reduction of thymic weight and the number of cells as compared to the control 1G mice (Fig 1A), which is consistent with previous studies [10, 11]. To investigate the role of the vestibular apparatus in 2G-dependent effects, we performed surgery for lesion of the inner ear’s vestibular apparatus (VL) in some mice [33]. Impressively, thymic involution due to 2G exposure was remarkably alleviated in VL mice (Fig 1A). This suggests that sensing gravity change by the vestibular apparatus triggers 2G-depenent thymic involution.


Hypergravity Provokes a Temporary Reduction in CD4+CD8+ Thymocyte Number and a Persistent Decrease in Medullary Thymic Epithelial Cell Frequency in Mice.

Tateishi R, Akiyama N, Miyauchi M, Yoshinaga R, Sasanuma H, Kudo T, Shimbo M, Shinohara M, Obata K, Inoue J, Shirakawa M, Shiba D, Asahara H, Yoshida N, Takahashi S, Morita H, Akiyama T - PLoS ONE (2015)

The short-term hypergravity exposure causes a reduction of CD4+CD8+ double positive thymocytes in a vestibular apparatus-dependent manner.(A) Ratio of thymic weight to body weight (left) and total thymic cell number (right) of mice exposed to 2 g gravity (labeled as 2G) for 3 day or normal gravity control (labeled as C). Vestibular apparatus were surgically disrupted in some groups of mice (labeled as VL). N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and **P < 0.01 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (B) Flow cytometric analysis of thymocytes in mice exposed to 2G for 3 days. Thymocytes were analyzed by staining with CD4 and CD8α antibodies (left figures). Numbers in panels indicates percentage of each fraction. Percentages of CD4- and CD8-double positive thymocytes (CD4+CD8+DP) in total thymocytes are summarized in right figures. Mice were exposed to 2 g gravity (2G) for 3 days. “C” indicates 1G control. Vestibular apparatus are surgically disrupted in some groups of mice (VL). N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (C) Cell numbers of CD4+CD8+ (CD4+CD8+DP), CD4+CD8- (CD4SP), CD4-CD8+ (CD8SP), and CD4-CD8- (DN) fractions in mice exposed to 2G for 3days. N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test).
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4626100&req=5

pone.0141650.g001: The short-term hypergravity exposure causes a reduction of CD4+CD8+ double positive thymocytes in a vestibular apparatus-dependent manner.(A) Ratio of thymic weight to body weight (left) and total thymic cell number (right) of mice exposed to 2 g gravity (labeled as 2G) for 3 day or normal gravity control (labeled as C). Vestibular apparatus were surgically disrupted in some groups of mice (labeled as VL). N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and **P < 0.01 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (B) Flow cytometric analysis of thymocytes in mice exposed to 2G for 3 days. Thymocytes were analyzed by staining with CD4 and CD8α antibodies (left figures). Numbers in panels indicates percentage of each fraction. Percentages of CD4- and CD8-double positive thymocytes (CD4+CD8+DP) in total thymocytes are summarized in right figures. Mice were exposed to 2 g gravity (2G) for 3 days. “C” indicates 1G control. Vestibular apparatus are surgically disrupted in some groups of mice (VL). N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test). (C) Cell numbers of CD4+CD8+ (CD4+CD8+DP), CD4+CD8- (CD4SP), CD4-CD8+ (CD8SP), and CD4-CD8- (DN) fractions in mice exposed to 2G for 3days. N = 10 for C and 2G, N = 8 for C with VL, and N = 9 for 2G with VL. The asterisks indicate statistical significance at ***P < 0.001 and *P < 0.05 (Student’s t-test). NS indicates that the difference is not significant (Student’s t-test).
Mentions: Mice were exposed to 2G by chronic centrifugation. Exposure to 2G for 3 days significantly resulted in a reduction of thymic weight and the number of cells as compared to the control 1G mice (Fig 1A), which is consistent with previous studies [10, 11]. To investigate the role of the vestibular apparatus in 2G-dependent effects, we performed surgery for lesion of the inner ear’s vestibular apparatus (VL) in some mice [33]. Impressively, thymic involution due to 2G exposure was remarkably alleviated in VL mice (Fig 1A). This suggests that sensing gravity change by the vestibular apparatus triggers 2G-depenent thymic involution.

Bottom Line: We investigated the effects of hypergravity (2G) on murine thymic cells.Interestingly, a surgical lesion of the inner ear's vestibular apparatus inhibited these hypergravity effects.Overall, data suggest that 2G causes a temporary reduction of DP and a persistent reduction of mature mTECs in a vestibular system-dependent manner, and also dysregulates mTEC gene expression without involving the vestibular system.

View Article: PubMed Central - PubMed

Affiliation: Division of Cellular and Molecular Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan; Mouse epigenetics project, ISS/Kibo experiment, Japan Aerospace Exploration Agency, JAXA, Tsukuba, Japan.

ABSTRACT
Gravity change affects many immunological systems. We investigated the effects of hypergravity (2G) on murine thymic cells. Exposure of mice to 2G for three days reduced the frequency of CD4+CD8+ thymocytes (DP) and mature medullary thymic epithelial cells (mTECs), accompanied by an increment of keratin-5 and keratin-8 double-positive (K5+K8+) TECs that reportedly contain TEC progenitors. Whereas the reduction of DP was recovered by a 14-day exposure to 2G, the reduction of mature mTECs and the increment of K5+K8+ TEC persisted. Interestingly, a surgical lesion of the inner ear's vestibular apparatus inhibited these hypergravity effects. Quantitative PCR analysis revealed that the gene expression of Aire and RANK that are critical for mTEC function and development were up-regulated by the 3-day exposure and subsequently down-regulated by the 14-day exposure to 2G. Unexpectedly, this dynamic change in mTEC gene expression was independent of the vestibular apparatus. Overall, data suggest that 2G causes a temporary reduction of DP and a persistent reduction of mature mTECs in a vestibular system-dependent manner, and also dysregulates mTEC gene expression without involving the vestibular system. These data might provide insight on the impact of gravity change on thymic functions during spaceflight and living.

No MeSH data available.


Related in: MedlinePlus