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p38/MKP-1-regulated AKT coordinates macrophage transitions and resolution of inflammation during tissue repair.

Perdiguero E, Sousa-Victor P, Ruiz-Bonilla V, Jardí M, Caelles C, Serrano AL, Muñoz-Cánoves P - J. Cell Biol. (2011)

Bottom Line: Repair of damaged tissue requires the coordinated action of inflammatory and tissue-specific cells to restore homeostasis, but the underlying regulatory mechanisms are poorly understood.Conversely, miR-21-AKT interference altered homeostasis during tissue repair.This novel regulatory mechanism involving the appropriate balance of p38, MKP-1, miR-21, and AKT activities may have implications in chronic inflammatory degenerative diseases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cell Biology Group, Department of Experimental and Health Sciences, Pompeu Fabra University, 08003 Barcelona, Spain.

ABSTRACT
Repair of damaged tissue requires the coordinated action of inflammatory and tissue-specific cells to restore homeostasis, but the underlying regulatory mechanisms are poorly understood. In this paper, we report new roles for MKP-1 (mitogen-activated protein kinase [MAPK] phosphatase-1) in controlling macrophage phenotypic transitions necessary for appropriate muscle stem cell-dependent tissue repair. By restricting p38 MAPK activation, MKP-1 allows the early pro- to antiinflammatory macrophage transition and the later progression into a macrophage exhaustion-like state characterized by cytokine silencing, thereby permitting resolution of inflammation as tissue fully recovers. p38 hyperactivation in macrophages lacking MKP-1 induced the expression of microRNA-21 (miR-21), which in turn reduced PTEN (phosphatase and tensin homologue) levels, thereby extending AKT activation. In the absence of MKP-1, p38-induced AKT activity anticipated the acquisition of the antiinflammatory gene program and final cytokine silencing in macrophages, resulting in impaired tissue healing. Such defects were reversed by temporally controlled p38 inhibition. Conversely, miR-21-AKT interference altered homeostasis during tissue repair. This novel regulatory mechanism involving the appropriate balance of p38, MKP-1, miR-21, and AKT activities may have implications in chronic inflammatory degenerative diseases.

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Early p38-induced IL-1β stimulates the later expression of the antiinflammatory cytokines IL-10 and TGFβ in cultured macrophages. (A) Primary macrophages were cultured in vitro and stimulated with LPS. At the time of stimulation, or after 1.5 h, cells were treated or not treated with SB203580 (SB) for the indicated times. Comparative qPCR analysis. NT, nontreated cells. (B) Primary macrophages were treated with LPS ± SB203580, cycloheximide (CHX), or actinomycin D (Act D). (C) As in B, cells were treated with an IL-1β neutralizing antibody, control IgG antibody, or recombinant IL-1β for 24 h (in this case, in the absence of LPS). Means ± SEM of at least three experiments. *** or #, P < 0.001; **, P < 0.01; *, P < 0.05.
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fig5: Early p38-induced IL-1β stimulates the later expression of the antiinflammatory cytokines IL-10 and TGFβ in cultured macrophages. (A) Primary macrophages were cultured in vitro and stimulated with LPS. At the time of stimulation, or after 1.5 h, cells were treated or not treated with SB203580 (SB) for the indicated times. Comparative qPCR analysis. NT, nontreated cells. (B) Primary macrophages were treated with LPS ± SB203580, cycloheximide (CHX), or actinomycin D (Act D). (C) As in B, cells were treated with an IL-1β neutralizing antibody, control IgG antibody, or recombinant IL-1β for 24 h (in this case, in the absence of LPS). Means ± SEM of at least three experiments. *** or #, P < 0.001; **, P < 0.01; *, P < 0.05.

Mentions: Next, we aimed to investigate further the direct requirement of p38 to regulate this pro- to antiinflammatory macrophage transition. SB203580 treatment of WT macrophages (initiated at the same time or after endotoxin stimulation) reduced both the early proinflammatory (IL-1β and TNF) and the late antiinflammatory (TGFβ and IL-10) waves of cytokine expression (Fig. 5 A). Similar results were obtained when HMGB1 was used as an initiating stimulus (unpublished results). In addition, the late IL-10 and TGFβ mRNA induction in these cells was blocked by actinomycin D and by cycloheximide (CHX; Fig. 5 B), suggesting the requirement of a newly synthesized protein intermediate for antiinflammatory cytokine expression. When the function of IL-1β was blocked with an IL-1β neutralizing antibody, the late LPS-dependent IL-10 and TGFβ induction in macrophages was significantly reduced (Fig. 5 C). Conversely, recombinant IL-1β was able to induce the expression of both antiinflammatory cytokines (in the absence of LPS; Fig. 5 C). Interestingly, this latter effect did not require de novo protein synthesis but was dependent on p38 activity, as indicated from combined treatments with recombinant IL-1β/CHX and IL-1β/SB203580, respectively (unpublished data). This data strongly supports the direct action of IL-1β on antiinflammatory gene expression mediated by p38. Hence, in response to an initial insult, the early macrophage proinflammatory response (i.e., IL-1β and likely also TNF production) is required for the activation of the subsequent antiinflammatory response (i.e., IL-10 and TGFβ production), which in turn may help to terminate the overall inflammatory reaction. Collectively, this indicates that the p38–MKP-1–controlled transition of macrophages from a pro- to an antiinflammatory phenotype appears critical, first, to counter the early proinflammatory cytokine environment in the damaged tissue, and, second, to directly stimulate satellite cell–mediated differentiation and fusion to newly forming myofibers, thus ensuring timely and successful tissue regeneration.


p38/MKP-1-regulated AKT coordinates macrophage transitions and resolution of inflammation during tissue repair.

Perdiguero E, Sousa-Victor P, Ruiz-Bonilla V, Jardí M, Caelles C, Serrano AL, Muñoz-Cánoves P - J. Cell Biol. (2011)

Early p38-induced IL-1β stimulates the later expression of the antiinflammatory cytokines IL-10 and TGFβ in cultured macrophages. (A) Primary macrophages were cultured in vitro and stimulated with LPS. At the time of stimulation, or after 1.5 h, cells were treated or not treated with SB203580 (SB) for the indicated times. Comparative qPCR analysis. NT, nontreated cells. (B) Primary macrophages were treated with LPS ± SB203580, cycloheximide (CHX), or actinomycin D (Act D). (C) As in B, cells were treated with an IL-1β neutralizing antibody, control IgG antibody, or recombinant IL-1β for 24 h (in this case, in the absence of LPS). Means ± SEM of at least three experiments. *** or #, P < 0.001; **, P < 0.01; *, P < 0.05.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3198158&req=5

fig5: Early p38-induced IL-1β stimulates the later expression of the antiinflammatory cytokines IL-10 and TGFβ in cultured macrophages. (A) Primary macrophages were cultured in vitro and stimulated with LPS. At the time of stimulation, or after 1.5 h, cells were treated or not treated with SB203580 (SB) for the indicated times. Comparative qPCR analysis. NT, nontreated cells. (B) Primary macrophages were treated with LPS ± SB203580, cycloheximide (CHX), or actinomycin D (Act D). (C) As in B, cells were treated with an IL-1β neutralizing antibody, control IgG antibody, or recombinant IL-1β for 24 h (in this case, in the absence of LPS). Means ± SEM of at least three experiments. *** or #, P < 0.001; **, P < 0.01; *, P < 0.05.
Mentions: Next, we aimed to investigate further the direct requirement of p38 to regulate this pro- to antiinflammatory macrophage transition. SB203580 treatment of WT macrophages (initiated at the same time or after endotoxin stimulation) reduced both the early proinflammatory (IL-1β and TNF) and the late antiinflammatory (TGFβ and IL-10) waves of cytokine expression (Fig. 5 A). Similar results were obtained when HMGB1 was used as an initiating stimulus (unpublished results). In addition, the late IL-10 and TGFβ mRNA induction in these cells was blocked by actinomycin D and by cycloheximide (CHX; Fig. 5 B), suggesting the requirement of a newly synthesized protein intermediate for antiinflammatory cytokine expression. When the function of IL-1β was blocked with an IL-1β neutralizing antibody, the late LPS-dependent IL-10 and TGFβ induction in macrophages was significantly reduced (Fig. 5 C). Conversely, recombinant IL-1β was able to induce the expression of both antiinflammatory cytokines (in the absence of LPS; Fig. 5 C). Interestingly, this latter effect did not require de novo protein synthesis but was dependent on p38 activity, as indicated from combined treatments with recombinant IL-1β/CHX and IL-1β/SB203580, respectively (unpublished data). This data strongly supports the direct action of IL-1β on antiinflammatory gene expression mediated by p38. Hence, in response to an initial insult, the early macrophage proinflammatory response (i.e., IL-1β and likely also TNF production) is required for the activation of the subsequent antiinflammatory response (i.e., IL-10 and TGFβ production), which in turn may help to terminate the overall inflammatory reaction. Collectively, this indicates that the p38–MKP-1–controlled transition of macrophages from a pro- to an antiinflammatory phenotype appears critical, first, to counter the early proinflammatory cytokine environment in the damaged tissue, and, second, to directly stimulate satellite cell–mediated differentiation and fusion to newly forming myofibers, thus ensuring timely and successful tissue regeneration.

Bottom Line: Repair of damaged tissue requires the coordinated action of inflammatory and tissue-specific cells to restore homeostasis, but the underlying regulatory mechanisms are poorly understood.Conversely, miR-21-AKT interference altered homeostasis during tissue repair.This novel regulatory mechanism involving the appropriate balance of p38, MKP-1, miR-21, and AKT activities may have implications in chronic inflammatory degenerative diseases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cell Biology Group, Department of Experimental and Health Sciences, Pompeu Fabra University, 08003 Barcelona, Spain.

ABSTRACT
Repair of damaged tissue requires the coordinated action of inflammatory and tissue-specific cells to restore homeostasis, but the underlying regulatory mechanisms are poorly understood. In this paper, we report new roles for MKP-1 (mitogen-activated protein kinase [MAPK] phosphatase-1) in controlling macrophage phenotypic transitions necessary for appropriate muscle stem cell-dependent tissue repair. By restricting p38 MAPK activation, MKP-1 allows the early pro- to antiinflammatory macrophage transition and the later progression into a macrophage exhaustion-like state characterized by cytokine silencing, thereby permitting resolution of inflammation as tissue fully recovers. p38 hyperactivation in macrophages lacking MKP-1 induced the expression of microRNA-21 (miR-21), which in turn reduced PTEN (phosphatase and tensin homologue) levels, thereby extending AKT activation. In the absence of MKP-1, p38-induced AKT activity anticipated the acquisition of the antiinflammatory gene program and final cytokine silencing in macrophages, resulting in impaired tissue healing. Such defects were reversed by temporally controlled p38 inhibition. Conversely, miR-21-AKT interference altered homeostasis during tissue repair. This novel regulatory mechanism involving the appropriate balance of p38, MKP-1, miR-21, and AKT activities may have implications in chronic inflammatory degenerative diseases.

Show MeSH
Related in: MedlinePlus