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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.

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Enhanced proliferation and apoptosis, and reduced late secondary immunoglobulin responses of p21−/− B cells from male BXSB mice. (a) Increased p21 expression in B cells from older male BXSB mice. Sorted B cells (CD19+) from 3-mo-old wild-type male or female BXSB mice (n = 5 mice/group) were analyzed by RNase protection assay for expression of p21 and L32 (control). (b) Increased proliferation of p21−/− B cells after IgM cross-linking. Splenocytes (n = 3 mice/group) were stimulated with 10 μg/ml of soluble goat F(ab′)2 anti–mouse IgM in the presence of IL-4 and assessed for [3H]thymidine incorporation (mean ± SEM cpm). (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. (c) Enhanced AICD of p21−/− B cells. Annexin V positivity of B cells was assessed after anti-IgM stimulation with 10 μg/ml of soluble goat F(ab′)2 anti–mouse IgM (n = 3 mice/group). (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. (d) Anti-TNP antibody levels after primary and secondary immunizations. 2-mo-old male BXSB p21−/− and p21+/+ mice (n = 4 mice/group) were injected s.c. with 100 μg TNP-KLH emulsified in CFA. Secondary responses were assessed by boosting mice s.c. with 100 μg TNP-KLH in saline on day 21. Mice were bled at the indicated times, and serum was analyzed by ELISA. (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. *, P < 0.05 by Student's t test.
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fig6: Enhanced proliferation and apoptosis, and reduced late secondary immunoglobulin responses of p21−/− B cells from male BXSB mice. (a) Increased p21 expression in B cells from older male BXSB mice. Sorted B cells (CD19+) from 3-mo-old wild-type male or female BXSB mice (n = 5 mice/group) were analyzed by RNase protection assay for expression of p21 and L32 (control). (b) Increased proliferation of p21−/− B cells after IgM cross-linking. Splenocytes (n = 3 mice/group) were stimulated with 10 μg/ml of soluble goat F(ab′)2 anti–mouse IgM in the presence of IL-4 and assessed for [3H]thymidine incorporation (mean ± SEM cpm). (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. (c) Enhanced AICD of p21−/− B cells. Annexin V positivity of B cells was assessed after anti-IgM stimulation with 10 μg/ml of soluble goat F(ab′)2 anti–mouse IgM (n = 3 mice/group). (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. (d) Anti-TNP antibody levels after primary and secondary immunizations. 2-mo-old male BXSB p21−/− and p21+/+ mice (n = 4 mice/group) were injected s.c. with 100 μg TNP-KLH emulsified in CFA. Secondary responses were assessed by boosting mice s.c. with 100 μg TNP-KLH in saline on day 21. Mice were bled at the indicated times, and serum was analyzed by ELISA. (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. *, P < 0.05 by Student's t test.

Mentions: As reported for T cells, B cells from lupus-predisposed mice have also been shown to be both arrested in G1 and apoptosis resistant (10, 41). Indeed, we detected high p21 levels in male, but not female, B cells (Fig. 6 a). Accordingly, activation with anti-IgM plus IL-4 induced higher proliferation (Fig. 6 b; P < 0.05), and cross-linking with anti-IgM resulted in accelerated and enhanced apoptosis of p21−/− compared with wild-type B cells (Fig. 6 c; P < 0.05).


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 proliferation and apoptosis, and reduced late secondary immunoglobulin responses of p21−/− B cells from male BXSB mice. (a) Increased p21 expression in B cells from older male BXSB mice. Sorted B cells (CD19+) from 3-mo-old wild-type male or female BXSB mice (n = 5 mice/group) were analyzed by RNase protection assay for expression of p21 and L32 (control). (b) Increased proliferation of p21−/− B cells after IgM cross-linking. Splenocytes (n = 3 mice/group) were stimulated with 10 μg/ml of soluble goat F(ab′)2 anti–mouse IgM in the presence of IL-4 and assessed for [3H]thymidine incorporation (mean ± SEM cpm). (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. (c) Enhanced AICD of p21−/− B cells. Annexin V positivity of B cells was assessed after anti-IgM stimulation with 10 μg/ml of soluble goat F(ab′)2 anti–mouse IgM (n = 3 mice/group). (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. (d) Anti-TNP antibody levels after primary and secondary immunizations. 2-mo-old male BXSB p21−/− and p21+/+ mice (n = 4 mice/group) were injected s.c. with 100 μg TNP-KLH emulsified in CFA. Secondary responses were assessed by boosting mice s.c. with 100 μg TNP-KLH in saline on day 21. Mice were bled at the indicated times, and serum was analyzed by ELISA. (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. *, P < 0.05 by Student's t test.
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fig6: Enhanced proliferation and apoptosis, and reduced late secondary immunoglobulin responses of p21−/− B cells from male BXSB mice. (a) Increased p21 expression in B cells from older male BXSB mice. Sorted B cells (CD19+) from 3-mo-old wild-type male or female BXSB mice (n = 5 mice/group) were analyzed by RNase protection assay for expression of p21 and L32 (control). (b) Increased proliferation of p21−/− B cells after IgM cross-linking. Splenocytes (n = 3 mice/group) were stimulated with 10 μg/ml of soluble goat F(ab′)2 anti–mouse IgM in the presence of IL-4 and assessed for [3H]thymidine incorporation (mean ± SEM cpm). (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. (c) Enhanced AICD of p21−/− B cells. Annexin V positivity of B cells was assessed after anti-IgM stimulation with 10 μg/ml of soluble goat F(ab′)2 anti–mouse IgM (n = 3 mice/group). (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. (d) Anti-TNP antibody levels after primary and secondary immunizations. 2-mo-old male BXSB p21−/− and p21+/+ mice (n = 4 mice/group) were injected s.c. with 100 μg TNP-KLH emulsified in CFA. Secondary responses were assessed by boosting mice s.c. with 100 μg TNP-KLH in saline on day 21. Mice were bled at the indicated times, and serum was analyzed by ELISA. (•) BXSB p21−/− mice. (○) BXSB p21+/+ mice. *, P < 0.05 by Student's t test.
Mentions: As reported for T cells, B cells from lupus-predisposed mice have also been shown to be both arrested in G1 and apoptosis resistant (10, 41). Indeed, we detected high p21 levels in male, but not female, B cells (Fig. 6 a). Accordingly, activation with anti-IgM plus IL-4 induced higher proliferation (Fig. 6 b; P < 0.05), and cross-linking with anti-IgM resulted in accelerated and enhanced apoptosis of p21−/− compared with wild-type B cells (Fig. 6 c; P < 0.05).

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