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Caspase-8 inactivation in T cells increases necroptosis and suppresses autoimmunity in Bim-/- mice.

Bohgaki T, Mozo J, Salmena L, Matysiak-Zablocki E, Bohgaki M, Sanchez O, Strasser A, Hakem A, Hakem R - J. Cell Biol. (2011)

Bottom Line: Dysregulation of either the extrinsic or intrinsic apoptotic pathway can lead to various diseases including immune disorders and cancer.In addition to its role in the extrinsic apoptotic pathway, caspase-8 plays nonapoptotic functions and is essential for T cell homeostasis.We show that, similar to caspase-8(-/-) T cells, Bim(-/-) T cells that also lack caspase-8 displayed elevated levels of necroptosis and that inhibition of this cell death process fully rescued the survival and proliferation of these cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada.

ABSTRACT
Dysregulation of either the extrinsic or intrinsic apoptotic pathway can lead to various diseases including immune disorders and cancer. In addition to its role in the extrinsic apoptotic pathway, caspase-8 plays nonapoptotic functions and is essential for T cell homeostasis. The pro-apoptotic BH3-only Bcl-2 family member Bim is important for the intrinsic apoptotic pathway and its inactivation leads to autoimmunity that is further exacerbated by loss of function of the death receptor Fas. We report that inactivation of caspase-8 in T cells of Bim(-/-) mice restrained their autoimmunity and extended their life span. We show that, similar to caspase-8(-/-) T cells, Bim(-/-) T cells that also lack caspase-8 displayed elevated levels of necroptosis and that inhibition of this cell death process fully rescued the survival and proliferation of these cells. Collectively, our data demonstrate that inactivation of caspase-8 suppresses the survival and proliferative capacity of Bim(-/-) T cells and restrains autoimmunity in Bim(-/-) mice.

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Casapse-8 loss in Bim−/− T cells perturbs their pattern of cytokine production. (A) Gene expression levels of IL-2, IFN-γ, IL-4, and TNF in tcasp8−/−Bim−/−, tcasp8−/−, Bim−/−, and WT peripheral T cells stimulated with anti-CD3/anti-CD28 antibodies for 6 h. (B) Representative flow cytometric analysis of the intracellular levels of IL-2 in peripheral T cells stimulated with anti-CD3/anti-CD28 antibodies for 6 h. (C and D) Representative flow cytometric analysis of the intracellular levels of IFN-γ, IL-4, and IL-10 in CD4+ T cells under Th1- or Th2-specific culture conditions. (C) The ovals indicate IFN-γ+ (top) and IL-4+ cells (bottom). (D) The ovals indicate IL-10+ cells. *, P < 0.05 compared with WT control; •, P < 0.05 compared with tcasp8−/− control; Δ, P < 0.05 compared with Bim−/− control. Data are derived from three independent experiments of young mice for each genotype. Histograms represent the mean ± SEM (error bars).
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fig4: Casapse-8 loss in Bim−/− T cells perturbs their pattern of cytokine production. (A) Gene expression levels of IL-2, IFN-γ, IL-4, and TNF in tcasp8−/−Bim−/−, tcasp8−/−, Bim−/−, and WT peripheral T cells stimulated with anti-CD3/anti-CD28 antibodies for 6 h. (B) Representative flow cytometric analysis of the intracellular levels of IL-2 in peripheral T cells stimulated with anti-CD3/anti-CD28 antibodies for 6 h. (C and D) Representative flow cytometric analysis of the intracellular levels of IFN-γ, IL-4, and IL-10 in CD4+ T cells under Th1- or Th2-specific culture conditions. (C) The ovals indicate IFN-γ+ (top) and IL-4+ cells (bottom). (D) The ovals indicate IL-10+ cells. *, P < 0.05 compared with WT control; •, P < 0.05 compared with tcasp8−/− control; Δ, P < 0.05 compared with Bim−/− control. Data are derived from three independent experiments of young mice for each genotype. Histograms represent the mean ± SEM (error bars).

Mentions: CD4+ T cells play important roles in humoral and cellular immune responses, and are also involved in autoimmunity (Zhu et al., 2010). The most prominent subsets of CD4+ T cells are T helper (Th) cells Th1, Th2, and Th17 and regulatory T cells (Treg), as defined by their patterns of cytokine production and functions (Zhu et al., 2010). Cytokines play important roles in the immune system and are critical for inflammation, hematopoietic cell growth, and homeostasis (O’Shea et al., 2002; Kunz and Ibrahim, 2009; O’Shea and Paul, 2010). T cell cytokine production patterns can affect lymphocyte homeostasis and the development of autoimmunity (Feldmann, 2008; O’Shea and Paul, 2010). As the effector memory T cells were abnormally increased in old tcasp8−/−Bim−/−, tcasp8−/−, and Bim−/− mice compared with WT littermates, and as tcasp8−/− mice develop a lymphoproliferative disorder and Bim−/− mice develop systemic autoimmune disease (Bouillet et al., 1999; Salmena and Hakem, 2005), we examined the profile of cytokine production in tcasp8−/−Bim−/− mice and their littermate controls at the mRNA level and at the single cell level. First, we assessed the pattern of cytokine production in peripheral T cells and Treg (CD4+CD25+FoxP3+). As previously described (Ludwinski et al., 2009), the expression levels of interleukin 2 (IL-2), IL-6, IFN-γ, and IL-4 genes were reduced in T cells from Bim−/− mice compared with WT littermates (Figs. 4 A and S3 A). The levels of IL-2 mRNA and intracellular cytokines were comparable between tcasp8−/− and WT activated T cells (Fig. 4, A and B). In contrast, activated tcasp8−/− T cells displayed abnormally increased levels of IFN-γ and IL-6 mRNA, whereas expression of IL-4 mRNA was decreased compared with WT controls (Figs. 4 A and S3 A). When cytokine mRNA levels were examined in anti-CD3/anti-CD28 antibody-stimulated tcasp8−/−Bim−/− T cells, IL-2, IL-6, and IL-17A expression were found to be similar to those of Bim−/− T cells, whereas increased levels of IFN-γ and decreased levels of IL-4 and TNF were observed compared with Bim−/− control T cells (Fig. 4, A and B; and Fig. S3 A). Examination of Treg in spleens and LN of young mice indicated no difference in their ratio in tcasp8−/−Bim−/− mice compared with single mutant animals and WT littermates (Fig. S3 B).


Caspase-8 inactivation in T cells increases necroptosis and suppresses autoimmunity in Bim-/- mice.

Bohgaki T, Mozo J, Salmena L, Matysiak-Zablocki E, Bohgaki M, Sanchez O, Strasser A, Hakem A, Hakem R - J. Cell Biol. (2011)

Casapse-8 loss in Bim−/− T cells perturbs their pattern of cytokine production. (A) Gene expression levels of IL-2, IFN-γ, IL-4, and TNF in tcasp8−/−Bim−/−, tcasp8−/−, Bim−/−, and WT peripheral T cells stimulated with anti-CD3/anti-CD28 antibodies for 6 h. (B) Representative flow cytometric analysis of the intracellular levels of IL-2 in peripheral T cells stimulated with anti-CD3/anti-CD28 antibodies for 6 h. (C and D) Representative flow cytometric analysis of the intracellular levels of IFN-γ, IL-4, and IL-10 in CD4+ T cells under Th1- or Th2-specific culture conditions. (C) The ovals indicate IFN-γ+ (top) and IL-4+ cells (bottom). (D) The ovals indicate IL-10+ cells. *, P < 0.05 compared with WT control; •, P < 0.05 compared with tcasp8−/− control; Δ, P < 0.05 compared with Bim−/− control. Data are derived from three independent experiments of young mice for each genotype. Histograms represent the mean ± SEM (error bars).
© Copyright Policy - openaccess
Related In: Results  -  Collection

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fig4: Casapse-8 loss in Bim−/− T cells perturbs their pattern of cytokine production. (A) Gene expression levels of IL-2, IFN-γ, IL-4, and TNF in tcasp8−/−Bim−/−, tcasp8−/−, Bim−/−, and WT peripheral T cells stimulated with anti-CD3/anti-CD28 antibodies for 6 h. (B) Representative flow cytometric analysis of the intracellular levels of IL-2 in peripheral T cells stimulated with anti-CD3/anti-CD28 antibodies for 6 h. (C and D) Representative flow cytometric analysis of the intracellular levels of IFN-γ, IL-4, and IL-10 in CD4+ T cells under Th1- or Th2-specific culture conditions. (C) The ovals indicate IFN-γ+ (top) and IL-4+ cells (bottom). (D) The ovals indicate IL-10+ cells. *, P < 0.05 compared with WT control; •, P < 0.05 compared with tcasp8−/− control; Δ, P < 0.05 compared with Bim−/− control. Data are derived from three independent experiments of young mice for each genotype. Histograms represent the mean ± SEM (error bars).
Mentions: CD4+ T cells play important roles in humoral and cellular immune responses, and are also involved in autoimmunity (Zhu et al., 2010). The most prominent subsets of CD4+ T cells are T helper (Th) cells Th1, Th2, and Th17 and regulatory T cells (Treg), as defined by their patterns of cytokine production and functions (Zhu et al., 2010). Cytokines play important roles in the immune system and are critical for inflammation, hematopoietic cell growth, and homeostasis (O’Shea et al., 2002; Kunz and Ibrahim, 2009; O’Shea and Paul, 2010). T cell cytokine production patterns can affect lymphocyte homeostasis and the development of autoimmunity (Feldmann, 2008; O’Shea and Paul, 2010). As the effector memory T cells were abnormally increased in old tcasp8−/−Bim−/−, tcasp8−/−, and Bim−/− mice compared with WT littermates, and as tcasp8−/− mice develop a lymphoproliferative disorder and Bim−/− mice develop systemic autoimmune disease (Bouillet et al., 1999; Salmena and Hakem, 2005), we examined the profile of cytokine production in tcasp8−/−Bim−/− mice and their littermate controls at the mRNA level and at the single cell level. First, we assessed the pattern of cytokine production in peripheral T cells and Treg (CD4+CD25+FoxP3+). As previously described (Ludwinski et al., 2009), the expression levels of interleukin 2 (IL-2), IL-6, IFN-γ, and IL-4 genes were reduced in T cells from Bim−/− mice compared with WT littermates (Figs. 4 A and S3 A). The levels of IL-2 mRNA and intracellular cytokines were comparable between tcasp8−/− and WT activated T cells (Fig. 4, A and B). In contrast, activated tcasp8−/− T cells displayed abnormally increased levels of IFN-γ and IL-6 mRNA, whereas expression of IL-4 mRNA was decreased compared with WT controls (Figs. 4 A and S3 A). When cytokine mRNA levels were examined in anti-CD3/anti-CD28 antibody-stimulated tcasp8−/−Bim−/− T cells, IL-2, IL-6, and IL-17A expression were found to be similar to those of Bim−/− T cells, whereas increased levels of IFN-γ and decreased levels of IL-4 and TNF were observed compared with Bim−/− control T cells (Fig. 4, A and B; and Fig. S3 A). Examination of Treg in spleens and LN of young mice indicated no difference in their ratio in tcasp8−/−Bim−/− mice compared with single mutant animals and WT littermates (Fig. S3 B).

Bottom Line: Dysregulation of either the extrinsic or intrinsic apoptotic pathway can lead to various diseases including immune disorders and cancer.In addition to its role in the extrinsic apoptotic pathway, caspase-8 plays nonapoptotic functions and is essential for T cell homeostasis.We show that, similar to caspase-8(-/-) T cells, Bim(-/-) T cells that also lack caspase-8 displayed elevated levels of necroptosis and that inhibition of this cell death process fully rescued the survival and proliferation of these cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada.

ABSTRACT
Dysregulation of either the extrinsic or intrinsic apoptotic pathway can lead to various diseases including immune disorders and cancer. In addition to its role in the extrinsic apoptotic pathway, caspase-8 plays nonapoptotic functions and is essential for T cell homeostasis. The pro-apoptotic BH3-only Bcl-2 family member Bim is important for the intrinsic apoptotic pathway and its inactivation leads to autoimmunity that is further exacerbated by loss of function of the death receptor Fas. We report that inactivation of caspase-8 in T cells of Bim(-/-) mice restrained their autoimmunity and extended their life span. We show that, similar to caspase-8(-/-) T cells, Bim(-/-) T cells that also lack caspase-8 displayed elevated levels of necroptosis and that inhibition of this cell death process fully rescued the survival and proliferation of these cells. Collectively, our data demonstrate that inactivation of caspase-8 suppresses the survival and proliferative capacity of Bim(-/-) T cells and restrains autoimmunity in Bim(-/-) mice.

Show MeSH
Related in: MedlinePlus