Limits...
Deficiency of the cyclin kinase inhibitor p21(WAF-1/CIP-1) promotes apoptosis of activated/memory T cells and inhibits spontaneous systemic autoimmunity.

Lawson BR, Baccala R, Song J, Croft M, Kono DH, Theofilopoulos AN - J. Exp. Med. (2004)

Bottom Line: Absence of p21 resulted in enhanced Fas/FasL-mediated activation-induced T cell death, increased activation of procaspases 8 and 3, and loss of mitochondrial transmembrane potential.Increased apoptosis was also associated with p53 up-regulation and a modest shift in the ratio of Bax/Bcl-2 toward the proapoptotic Bax.Thus, modulation of the cell cycle pathway may be a novel approach to reduce apoptosis-resistant pathogenic lymphocytes and to ameliorate systemic autoimmunity.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.

ABSTRACT
A characteristic feature of systemic lupus erythematosus is the accumulation of activated/memory T and B cells. These G0/G1-arrested cells express high levels of cyclin-dependent kinase inhibitors such as p21, are resistant to proliferation and apoptosis, and produce large amounts of proinflammatory cytokines. Herein, we show that ablation of p21 in lupus-prone mice allows these cells to reenter the cell cycle and undergo apoptosis, leading to autoimmune disease reduction. Absence of p21 resulted in enhanced Fas/FasL-mediated activation-induced T cell death, increased activation of procaspases 8 and 3, and loss of mitochondrial transmembrane potential. Increased apoptosis was also associated with p53 up-regulation and a modest shift in the ratio of Bax/Bcl-2 toward the proapoptotic Bax. Proliferation and apoptosis of B cells were also increased in p21-/- lupus mice. Thus, modulation of the cell cycle pathway may be a novel approach to reduce apoptosis-resistant pathogenic lymphocytes and to ameliorate systemic autoimmunity.

Show MeSH

Related in: MedlinePlus

Enhanced Fas/FasL-mediated apoptosis of p21−/− T cells from male BXSB mice. (a) Increased anti-Fas induced apoptosis of p21−/− T cells. LN cells (n = 3 mice/group) were first stimulated with 10 μg/ml of soluble anti-CD3 and 5 μg/ml CD28 for 48 h and then with 5 μg/ml anti-Fas antibody and analyzed for percentage of apoptotic (Annexin V+PI−) CD4+ T cells. (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. *, P < 0.05. (b) Increased caspase 8 and 3 activation and reduced mitochrondrial membrane potential (ΔΨm) in p21−/− T cells after induction of AICD. T cells (n = 3 mice/group) were stimulated with 0.1 μg/ml of soluble anti-CD3, religated with 10 μg/ml of plate-bound anti-CD3, and analyzed by FACS® for activation of caspases 8 and 3 and for change in mitochondrial transmembrane potential. The percentage of cells expressing activated caspases 8 or 3 and reduced ΔΨm is indicated (mean ± SEM). P < 0.05 between p21+/+ and p21−/− for all time points shown. (c) Fas blockade inhibits AICD of p21+/+ and p21−/− T cells. T cells (n = 3 mice/group) were stimulated with 0.1 μg/ml of soluble anti-CD3 for 48 h, religated with 10 μg/ml of plate-bound anti-CD3 in the presence or absence of 10 μg/ml of blocking anti-FasL antibody, and analyzed for Annexin V positivity. Similar inhibition was also observed after treatment with Fas-blocking soluble Fas/Fc. (♦) BXSB p21−/− mice plus anti-FasL. (▪) BXSB p21+/+ mice plus anti-FasL. (⋄) BXSB p21−/− mice. (□) BXSB p21+/+ mice. *, P < 0.05 for untreated (⋄ or □) versus anti-FasL–treated groups (♦ or ▪) at 48 and 72 h, and for untreated p21−/− (⋄) versus p21+/+ (□) mice at 72 h.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2211831&req=5

fig4: Enhanced Fas/FasL-mediated apoptosis of p21−/− T cells from male BXSB mice. (a) Increased anti-Fas induced apoptosis of p21−/− T cells. LN cells (n = 3 mice/group) were first stimulated with 10 μg/ml of soluble anti-CD3 and 5 μg/ml CD28 for 48 h and then with 5 μg/ml anti-Fas antibody and analyzed for percentage of apoptotic (Annexin V+PI−) CD4+ T cells. (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. *, P < 0.05. (b) Increased caspase 8 and 3 activation and reduced mitochrondrial membrane potential (ΔΨm) in p21−/− T cells after induction of AICD. T cells (n = 3 mice/group) were stimulated with 0.1 μg/ml of soluble anti-CD3, religated with 10 μg/ml of plate-bound anti-CD3, and analyzed by FACS® for activation of caspases 8 and 3 and for change in mitochondrial transmembrane potential. The percentage of cells expressing activated caspases 8 or 3 and reduced ΔΨm is indicated (mean ± SEM). P < 0.05 between p21+/+ and p21−/− for all time points shown. (c) Fas blockade inhibits AICD of p21+/+ and p21−/− T cells. T cells (n = 3 mice/group) were stimulated with 0.1 μg/ml of soluble anti-CD3 for 48 h, religated with 10 μg/ml of plate-bound anti-CD3 in the presence or absence of 10 μg/ml of blocking anti-FasL antibody, and analyzed for Annexin V positivity. Similar inhibition was also observed after treatment with Fas-blocking soluble Fas/Fc. (♦) BXSB p21−/− mice plus anti-FasL. (▪) BXSB p21+/+ mice plus anti-FasL. (⋄) BXSB p21−/− mice. (□) BXSB p21+/+ mice. *, P < 0.05 for untreated (⋄ or □) versus anti-FasL–treated groups (♦ or ▪) at 48 and 72 h, and for untreated p21−/− (⋄) versus p21+/+ (□) mice at 72 h.

Mentions: Fas and FasL expression of anti-CD3– and anti-CD28–activated p21+/+ and p21−/− CD4 T cells was equivalent (unpublished data). However, anti-Fas–induced apoptosis of activated CD4 T cells was higher in p21-deficient T cells (Fig. 4 a). Accordingly, kinetic studies showed that the frequency of p21−/− T cells undergoing AICD that had converted initiator procaspase 8 and effector procaspase 3 to active caspases was significantly higher than wild-type cells at all time points (Fig. 4 b). Similarly, loss of mitochondrial transmembrane potential was more pronounced in p21−/− than p21+/+ cells (Fig. 4 b). However, AICD was inhibited in both types of T cells by either anti-FasL mAb (Fig. 4 c) or Fas/Fc (not depicted). Thus, as expected, the Fas/FasL pathway is the primary mediator of AICD in p21+/+ and p21−/− T cells, but the CD95 signaling cascade and associated events are amplified in p21−/− cells.


Deficiency of the cyclin kinase inhibitor p21(WAF-1/CIP-1) promotes apoptosis of activated/memory T cells and inhibits spontaneous systemic autoimmunity.

Lawson BR, Baccala R, Song J, Croft M, Kono DH, Theofilopoulos AN - J. Exp. Med. (2004)

Enhanced Fas/FasL-mediated apoptosis of p21−/− T cells from male BXSB mice. (a) Increased anti-Fas induced apoptosis of p21−/− T cells. LN cells (n = 3 mice/group) were first stimulated with 10 μg/ml of soluble anti-CD3 and 5 μg/ml CD28 for 48 h and then with 5 μg/ml anti-Fas antibody and analyzed for percentage of apoptotic (Annexin V+PI−) CD4+ T cells. (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. *, P < 0.05. (b) Increased caspase 8 and 3 activation and reduced mitochrondrial membrane potential (ΔΨm) in p21−/− T cells after induction of AICD. T cells (n = 3 mice/group) were stimulated with 0.1 μg/ml of soluble anti-CD3, religated with 10 μg/ml of plate-bound anti-CD3, and analyzed by FACS® for activation of caspases 8 and 3 and for change in mitochondrial transmembrane potential. The percentage of cells expressing activated caspases 8 or 3 and reduced ΔΨm is indicated (mean ± SEM). P < 0.05 between p21+/+ and p21−/− for all time points shown. (c) Fas blockade inhibits AICD of p21+/+ and p21−/− T cells. T cells (n = 3 mice/group) were stimulated with 0.1 μg/ml of soluble anti-CD3 for 48 h, religated with 10 μg/ml of plate-bound anti-CD3 in the presence or absence of 10 μg/ml of blocking anti-FasL antibody, and analyzed for Annexin V positivity. Similar inhibition was also observed after treatment with Fas-blocking soluble Fas/Fc. (♦) BXSB p21−/− mice plus anti-FasL. (▪) BXSB p21+/+ mice plus anti-FasL. (⋄) BXSB p21−/− mice. (□) BXSB p21+/+ mice. *, P < 0.05 for untreated (⋄ or □) versus anti-FasL–treated groups (♦ or ▪) at 48 and 72 h, and for untreated p21−/− (⋄) versus p21+/+ (□) mice at 72 h.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211831&req=5

fig4: Enhanced Fas/FasL-mediated apoptosis of p21−/− T cells from male BXSB mice. (a) Increased anti-Fas induced apoptosis of p21−/− T cells. LN cells (n = 3 mice/group) were first stimulated with 10 μg/ml of soluble anti-CD3 and 5 μg/ml CD28 for 48 h and then with 5 μg/ml anti-Fas antibody and analyzed for percentage of apoptotic (Annexin V+PI−) CD4+ T cells. (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. *, P < 0.05. (b) Increased caspase 8 and 3 activation and reduced mitochrondrial membrane potential (ΔΨm) in p21−/− T cells after induction of AICD. T cells (n = 3 mice/group) were stimulated with 0.1 μg/ml of soluble anti-CD3, religated with 10 μg/ml of plate-bound anti-CD3, and analyzed by FACS® for activation of caspases 8 and 3 and for change in mitochondrial transmembrane potential. The percentage of cells expressing activated caspases 8 or 3 and reduced ΔΨm is indicated (mean ± SEM). P < 0.05 between p21+/+ and p21−/− for all time points shown. (c) Fas blockade inhibits AICD of p21+/+ and p21−/− T cells. T cells (n = 3 mice/group) were stimulated with 0.1 μg/ml of soluble anti-CD3 for 48 h, religated with 10 μg/ml of plate-bound anti-CD3 in the presence or absence of 10 μg/ml of blocking anti-FasL antibody, and analyzed for Annexin V positivity. Similar inhibition was also observed after treatment with Fas-blocking soluble Fas/Fc. (♦) BXSB p21−/− mice plus anti-FasL. (▪) BXSB p21+/+ mice plus anti-FasL. (⋄) BXSB p21−/− mice. (□) BXSB p21+/+ mice. *, P < 0.05 for untreated (⋄ or □) versus anti-FasL–treated groups (♦ or ▪) at 48 and 72 h, and for untreated p21−/− (⋄) versus p21+/+ (□) mice at 72 h.
Mentions: Fas and FasL expression of anti-CD3– and anti-CD28–activated p21+/+ and p21−/− CD4 T cells was equivalent (unpublished data). However, anti-Fas–induced apoptosis of activated CD4 T cells was higher in p21-deficient T cells (Fig. 4 a). Accordingly, kinetic studies showed that the frequency of p21−/− T cells undergoing AICD that had converted initiator procaspase 8 and effector procaspase 3 to active caspases was significantly higher than wild-type cells at all time points (Fig. 4 b). Similarly, loss of mitochondrial transmembrane potential was more pronounced in p21−/− than p21+/+ cells (Fig. 4 b). However, AICD was inhibited in both types of T cells by either anti-FasL mAb (Fig. 4 c) or Fas/Fc (not depicted). Thus, as expected, the Fas/FasL pathway is the primary mediator of AICD in p21+/+ and p21−/− T cells, but the CD95 signaling cascade and associated events are amplified in p21−/− cells.

Bottom Line: Absence of p21 resulted in enhanced Fas/FasL-mediated activation-induced T cell death, increased activation of procaspases 8 and 3, and loss of mitochondrial transmembrane potential.Increased apoptosis was also associated with p53 up-regulation and a modest shift in the ratio of Bax/Bcl-2 toward the proapoptotic Bax.Thus, modulation of the cell cycle pathway may be a novel approach to reduce apoptosis-resistant pathogenic lymphocytes and to ameliorate systemic autoimmunity.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.

ABSTRACT
A characteristic feature of systemic lupus erythematosus is the accumulation of activated/memory T and B cells. These G0/G1-arrested cells express high levels of cyclin-dependent kinase inhibitors such as p21, are resistant to proliferation and apoptosis, and produce large amounts of proinflammatory cytokines. Herein, we show that ablation of p21 in lupus-prone mice allows these cells to reenter the cell cycle and undergo apoptosis, leading to autoimmune disease reduction. Absence of p21 resulted in enhanced Fas/FasL-mediated activation-induced T cell death, increased activation of procaspases 8 and 3, and loss of mitochondrial transmembrane potential. Increased apoptosis was also associated with p53 up-regulation and a modest shift in the ratio of Bax/Bcl-2 toward the proapoptotic Bax. Proliferation and apoptosis of B cells were also increased in p21-/- lupus mice. Thus, modulation of the cell cycle pathway may be a novel approach to reduce apoptosis-resistant pathogenic lymphocytes and to ameliorate systemic autoimmunity.

Show MeSH
Related in: MedlinePlus