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Counter-regulation of T cell effector function by differentially activated p38.

Alam MS, Gaida MM, Ogawa Y, Kolios AG, Lasitschka F, Ashwell JD - J. Exp. Med. (2014)

Bottom Line: Unlike the MAP kinase (MAPK) cascade that phosphorylates p38 on the activation loop, T cell receptor (TCR) signaling results in phosphorylation on Tyr-323 (pY323, alternative pathway).Notably, UVB treatment of human psoriatic lesions reduced skin-infiltrating p38 pY323(+) T cell IRF4 and IL-17 production.Thus, distinct mechanisms of p38 activation converge on NFATc1 with opposing effects on T cell immunity, which may underlie the beneficial effect of phototherapy on psoriasis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Immune Cell Biology, Center for Cancer Research; Dermatology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.

ABSTRACT
Unlike the MAP kinase (MAPK) cascade that phosphorylates p38 on the activation loop, T cell receptor (TCR) signaling results in phosphorylation on Tyr-323 (pY323, alternative pathway). Using mice expressing p38α and p38β with Y323F substitutions, we show that alternatively but not MAPK cascade-activated p38 up-regulates the transcription factors NFATc1 and IRF4, which are required for proliferation and cytokine production. Conversely, activation of p38 with UV or osmotic shock mitigated TCR-mediated activation by phosphorylation and cytoplasmic retention of NFATc1. Notably, UVB treatment of human psoriatic lesions reduced skin-infiltrating p38 pY323(+) T cell IRF4 and IL-17 production. Thus, distinct mechanisms of p38 activation converge on NFATc1 with opposing effects on T cell immunity, which may underlie the beneficial effect of phototherapy on psoriasis.

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Effect of UV on skin-infiltrating T cells. (A) Mice were exposed or not to UV radiation as described in Materials and methods and, 1 h later, skin sections were obtained and immunostained for CD3 (not depicted) and dual phospho-p38 (pT180/pY182). Phospho-p38–positive T cells are indicated with arrowheads, keratinocytes with arrows, and dermal fibroblasts with asterisks. Bars: 200 µm (left); 100 µm(right). Data are representative of five mice per group from two independent experiments. (B) Purified CD4+ T cells from the skin of UV treated or untreated mice were stimulated in vitro with anti-CD3/CD28 for 24 h, and Irf4 mRNA expression was measured by real-time PCR. Results are the mean ± SEM of two independent experiments with a total of 5 mice per group. *, P < 0.05, NS, not statistically significant (unpaired two-tailed Student’s t test). (C) Immunohistochemical staining of human psoriatic skin lesions with anti-CD3 or phospho-p38 Y323 (p38 pY323)-specific antibodies. The insets in the middle pane show the T cell–poor and T cell–rich areas that are enlarged in the left and right panes for CD3 and the top and bottom panes for p38 pY323. Arrows indicate examples of p38 pY323-positive cells (n = 3 patients; Bars: 1 mm (middle); 50 µm (outer panels). (D) Immunofluorescence staining for p38 pY323 (cyan), IRF4 (green), IL-17A (red), and the corresponding isotype control of representative psoriatic skin lesions biopsies before and after UVB treatment (Bar, 100 µm). (E) Quantitation of p38 pY323+ cells that are also positive for IRF4 and IL-17A (triple positive) in the skin of 6 patients before treatment and 3 of these after UVB treatment. *, P < 0.05. NS, not significant (unpaired two-tailed Student’s t test).
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fig5: Effect of UV on skin-infiltrating T cells. (A) Mice were exposed or not to UV radiation as described in Materials and methods and, 1 h later, skin sections were obtained and immunostained for CD3 (not depicted) and dual phospho-p38 (pT180/pY182). Phospho-p38–positive T cells are indicated with arrowheads, keratinocytes with arrows, and dermal fibroblasts with asterisks. Bars: 200 µm (left); 100 µm(right). Data are representative of five mice per group from two independent experiments. (B) Purified CD4+ T cells from the skin of UV treated or untreated mice were stimulated in vitro with anti-CD3/CD28 for 24 h, and Irf4 mRNA expression was measured by real-time PCR. Results are the mean ± SEM of two independent experiments with a total of 5 mice per group. *, P < 0.05, NS, not statistically significant (unpaired two-tailed Student’s t test). (C) Immunohistochemical staining of human psoriatic skin lesions with anti-CD3 or phospho-p38 Y323 (p38 pY323)-specific antibodies. The insets in the middle pane show the T cell–poor and T cell–rich areas that are enlarged in the left and right panes for CD3 and the top and bottom panes for p38 pY323. Arrows indicate examples of p38 pY323-positive cells (n = 3 patients; Bars: 1 mm (middle); 50 µm (outer panels). (D) Immunofluorescence staining for p38 pY323 (cyan), IRF4 (green), IL-17A (red), and the corresponding isotype control of representative psoriatic skin lesions biopsies before and after UVB treatment (Bar, 100 µm). (E) Quantitation of p38 pY323+ cells that are also positive for IRF4 and IL-17A (triple positive) in the skin of 6 patients before treatment and 3 of these after UVB treatment. *, P < 0.05. NS, not significant (unpaired two-tailed Student’s t test).

Mentions: To ask if activation of p38 via a stress pathway could affect T cell responses in a biologically relevant setting, we characterized p38 activation and Irf4-induction in T cells from UV-treated skin. Once after exposure to the minimum erythema dose (MED) of UV there was a marked increase in dual-phospho p38 in keratinocytes, dermal fibroblasts, and skin-resident T cells (Fig. 5 A). Strikingly, TCR-mediated stimulation of CD4+ T cells isolated from UV-treated skin induced Irf4 at much lower levels than in T cells from untreated skin, whereas there was relatively little effect on Irf8 (Fig. 5 B).


Counter-regulation of T cell effector function by differentially activated p38.

Alam MS, Gaida MM, Ogawa Y, Kolios AG, Lasitschka F, Ashwell JD - J. Exp. Med. (2014)

Effect of UV on skin-infiltrating T cells. (A) Mice were exposed or not to UV radiation as described in Materials and methods and, 1 h later, skin sections were obtained and immunostained for CD3 (not depicted) and dual phospho-p38 (pT180/pY182). Phospho-p38–positive T cells are indicated with arrowheads, keratinocytes with arrows, and dermal fibroblasts with asterisks. Bars: 200 µm (left); 100 µm(right). Data are representative of five mice per group from two independent experiments. (B) Purified CD4+ T cells from the skin of UV treated or untreated mice were stimulated in vitro with anti-CD3/CD28 for 24 h, and Irf4 mRNA expression was measured by real-time PCR. Results are the mean ± SEM of two independent experiments with a total of 5 mice per group. *, P < 0.05, NS, not statistically significant (unpaired two-tailed Student’s t test). (C) Immunohistochemical staining of human psoriatic skin lesions with anti-CD3 or phospho-p38 Y323 (p38 pY323)-specific antibodies. The insets in the middle pane show the T cell–poor and T cell–rich areas that are enlarged in the left and right panes for CD3 and the top and bottom panes for p38 pY323. Arrows indicate examples of p38 pY323-positive cells (n = 3 patients; Bars: 1 mm (middle); 50 µm (outer panels). (D) Immunofluorescence staining for p38 pY323 (cyan), IRF4 (green), IL-17A (red), and the corresponding isotype control of representative psoriatic skin lesions biopsies before and after UVB treatment (Bar, 100 µm). (E) Quantitation of p38 pY323+ cells that are also positive for IRF4 and IL-17A (triple positive) in the skin of 6 patients before treatment and 3 of these after UVB treatment. *, P < 0.05. NS, not significant (unpaired two-tailed Student’s t test).
© Copyright Policy - openaccess
Related In: Results  -  Collection

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Show All Figures
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fig5: Effect of UV on skin-infiltrating T cells. (A) Mice were exposed or not to UV radiation as described in Materials and methods and, 1 h later, skin sections were obtained and immunostained for CD3 (not depicted) and dual phospho-p38 (pT180/pY182). Phospho-p38–positive T cells are indicated with arrowheads, keratinocytes with arrows, and dermal fibroblasts with asterisks. Bars: 200 µm (left); 100 µm(right). Data are representative of five mice per group from two independent experiments. (B) Purified CD4+ T cells from the skin of UV treated or untreated mice were stimulated in vitro with anti-CD3/CD28 for 24 h, and Irf4 mRNA expression was measured by real-time PCR. Results are the mean ± SEM of two independent experiments with a total of 5 mice per group. *, P < 0.05, NS, not statistically significant (unpaired two-tailed Student’s t test). (C) Immunohistochemical staining of human psoriatic skin lesions with anti-CD3 or phospho-p38 Y323 (p38 pY323)-specific antibodies. The insets in the middle pane show the T cell–poor and T cell–rich areas that are enlarged in the left and right panes for CD3 and the top and bottom panes for p38 pY323. Arrows indicate examples of p38 pY323-positive cells (n = 3 patients; Bars: 1 mm (middle); 50 µm (outer panels). (D) Immunofluorescence staining for p38 pY323 (cyan), IRF4 (green), IL-17A (red), and the corresponding isotype control of representative psoriatic skin lesions biopsies before and after UVB treatment (Bar, 100 µm). (E) Quantitation of p38 pY323+ cells that are also positive for IRF4 and IL-17A (triple positive) in the skin of 6 patients before treatment and 3 of these after UVB treatment. *, P < 0.05. NS, not significant (unpaired two-tailed Student’s t test).
Mentions: To ask if activation of p38 via a stress pathway could affect T cell responses in a biologically relevant setting, we characterized p38 activation and Irf4-induction in T cells from UV-treated skin. Once after exposure to the minimum erythema dose (MED) of UV there was a marked increase in dual-phospho p38 in keratinocytes, dermal fibroblasts, and skin-resident T cells (Fig. 5 A). Strikingly, TCR-mediated stimulation of CD4+ T cells isolated from UV-treated skin induced Irf4 at much lower levels than in T cells from untreated skin, whereas there was relatively little effect on Irf8 (Fig. 5 B).

Bottom Line: Unlike the MAP kinase (MAPK) cascade that phosphorylates p38 on the activation loop, T cell receptor (TCR) signaling results in phosphorylation on Tyr-323 (pY323, alternative pathway).Notably, UVB treatment of human psoriatic lesions reduced skin-infiltrating p38 pY323(+) T cell IRF4 and IL-17 production.Thus, distinct mechanisms of p38 activation converge on NFATc1 with opposing effects on T cell immunity, which may underlie the beneficial effect of phototherapy on psoriasis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Immune Cell Biology, Center for Cancer Research; Dermatology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.

ABSTRACT
Unlike the MAP kinase (MAPK) cascade that phosphorylates p38 on the activation loop, T cell receptor (TCR) signaling results in phosphorylation on Tyr-323 (pY323, alternative pathway). Using mice expressing p38α and p38β with Y323F substitutions, we show that alternatively but not MAPK cascade-activated p38 up-regulates the transcription factors NFATc1 and IRF4, which are required for proliferation and cytokine production. Conversely, activation of p38 with UV or osmotic shock mitigated TCR-mediated activation by phosphorylation and cytoplasmic retention of NFATc1. Notably, UVB treatment of human psoriatic lesions reduced skin-infiltrating p38 pY323(+) T cell IRF4 and IL-17 production. Thus, distinct mechanisms of p38 activation converge on NFATc1 with opposing effects on T cell immunity, which may underlie the beneficial effect of phototherapy on psoriasis.

Show MeSH
Related in: MedlinePlus