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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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Forced premature expression of the antiinflammatory cytokine IL-10 impairs normal muscle repair. (A) Recombinant IL-10 or IGF-1 (used as a control) was injected twice during the early stages of regeneration after CTX injury (Inj.). 7-d injured gastrocnemius muscles obtained from vehicle-treated mice or mice treated with IL-10 at 7 d postinjury (P.I.) were stained with an anti-eMHC antibody, and the mean area of regenerating myofibers was calculated. Bar, 50 µm. (B) WT satellite cells were cultured in GM for 24 h with 10 ng/ml IL-10, 30 ng/ml TNF, or a combination of both. (left) Cells were incubated for 1 h with BrdU, and positive cells were quantified. (right) Satellite cells were cultured in DM for 48 h with the same treatment, and Myogenin and MCK expression was analyzed. (C) Single myofibers, with their associated satellite cells, isolated from mouse muscles were cultured ex vivo in GM as in B for 72 h. Satellite cells were stained for Myogenin (Mgn; green) and TO-PRO-3 (red), and the number of positive cells in each fiber was counted. Bar, 100 µm. NT, nontreated cells. Means ± SEM of at least three experiments. **, P < 0.01.
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fig4: Forced premature expression of the antiinflammatory cytokine IL-10 impairs normal muscle repair. (A) Recombinant IL-10 or IGF-1 (used as a control) was injected twice during the early stages of regeneration after CTX injury (Inj.). 7-d injured gastrocnemius muscles obtained from vehicle-treated mice or mice treated with IL-10 at 7 d postinjury (P.I.) were stained with an anti-eMHC antibody, and the mean area of regenerating myofibers was calculated. Bar, 50 µm. (B) WT satellite cells were cultured in GM for 24 h with 10 ng/ml IL-10, 30 ng/ml TNF, or a combination of both. (left) Cells were incubated for 1 h with BrdU, and positive cells were quantified. (right) Satellite cells were cultured in DM for 48 h with the same treatment, and Myogenin and MCK expression was analyzed. (C) Single myofibers, with their associated satellite cells, isolated from mouse muscles were cultured ex vivo in GM as in B for 72 h. Satellite cells were stained for Myogenin (Mgn; green) and TO-PRO-3 (red), and the number of positive cells in each fiber was counted. Bar, 100 µm. NT, nontreated cells. Means ± SEM of at least three experiments. **, P < 0.01.

Mentions: To test whether the premature expression of antiinflammatory cytokines in MKP-1−/− muscle macrophages (overlapping with that of proinflammatory cytokines) might contribute in part to the inefficient repair of MKP-1−/− muscles, we tried to recapitulate this mixed inflammatory status in injured WT muscle and analyzed the consequences on new myofiber growth. Local delivery of IL-10 early after WT muscle injury (2 and 4 d after CTX injection, when proinflammatory cytokine expression is predominant) reduced the CSA of newly forming fibers measured at 7 d after injury compared with saline-treated contralateral damaged muscle (Fig. 4 A). As a control, no reduction of myofiber CSA was observed after IGF-1 (insulin-like growth factor 1) administration. These in vivo results were complemented with two ex vivo satellite cell–based models. Treatment with IL-10 was found to reverse the proproliferative effect of TNF on cultured satellite cells, as shown by BrdU incorporation (Fig. 4 B, left) and cell counting (after 5 d in culture, TNF increased the number of satellite cells by 25 ± 3.5% over WT numbers), whereas TNF/IL-10 co-stimulation did not have a proproliferative effect. Conversely, the differentiation-promoting effect of IL-10 on satellite cells, as shown by enhanced Myogenin and muscle creatine kinase (MCK) expression, was abolished by cotreatment with TNF (Fig. 4 B, right). Finally, in isolated single myofibers from adult mouse muscle, the simultaneous addition of TNF and IL-10 for 72 h reduced the number of Myogenin+ satellite cells per fiber (Fig. 4 C). Thus, timely, sequential expression of pro- and antiinflammatory cytokines produced by specific macrophage subsets appears critical to allow, first, satellite cell proliferation and, later, their differentiation and fusion into myofibers. Consistent with this, premature initiation of the antiinflammatory cytokine program in injured WT muscle with IL-10 (mimicking MKP-1 loss) led to inefficient tissue healing.


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)

Forced premature expression of the antiinflammatory cytokine IL-10 impairs normal muscle repair. (A) Recombinant IL-10 or IGF-1 (used as a control) was injected twice during the early stages of regeneration after CTX injury (Inj.). 7-d injured gastrocnemius muscles obtained from vehicle-treated mice or mice treated with IL-10 at 7 d postinjury (P.I.) were stained with an anti-eMHC antibody, and the mean area of regenerating myofibers was calculated. Bar, 50 µm. (B) WT satellite cells were cultured in GM for 24 h with 10 ng/ml IL-10, 30 ng/ml TNF, or a combination of both. (left) Cells were incubated for 1 h with BrdU, and positive cells were quantified. (right) Satellite cells were cultured in DM for 48 h with the same treatment, and Myogenin and MCK expression was analyzed. (C) Single myofibers, with their associated satellite cells, isolated from mouse muscles were cultured ex vivo in GM as in B for 72 h. Satellite cells were stained for Myogenin (Mgn; green) and TO-PRO-3 (red), and the number of positive cells in each fiber was counted. Bar, 100 µm. NT, nontreated cells. Means ± SEM of at least three experiments. **, P < 0.01.
© Copyright Policy - openaccess
Related In: Results  -  Collection

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

fig4: Forced premature expression of the antiinflammatory cytokine IL-10 impairs normal muscle repair. (A) Recombinant IL-10 or IGF-1 (used as a control) was injected twice during the early stages of regeneration after CTX injury (Inj.). 7-d injured gastrocnemius muscles obtained from vehicle-treated mice or mice treated with IL-10 at 7 d postinjury (P.I.) were stained with an anti-eMHC antibody, and the mean area of regenerating myofibers was calculated. Bar, 50 µm. (B) WT satellite cells were cultured in GM for 24 h with 10 ng/ml IL-10, 30 ng/ml TNF, or a combination of both. (left) Cells were incubated for 1 h with BrdU, and positive cells were quantified. (right) Satellite cells were cultured in DM for 48 h with the same treatment, and Myogenin and MCK expression was analyzed. (C) Single myofibers, with their associated satellite cells, isolated from mouse muscles were cultured ex vivo in GM as in B for 72 h. Satellite cells were stained for Myogenin (Mgn; green) and TO-PRO-3 (red), and the number of positive cells in each fiber was counted. Bar, 100 µm. NT, nontreated cells. Means ± SEM of at least three experiments. **, P < 0.01.
Mentions: To test whether the premature expression of antiinflammatory cytokines in MKP-1−/− muscle macrophages (overlapping with that of proinflammatory cytokines) might contribute in part to the inefficient repair of MKP-1−/− muscles, we tried to recapitulate this mixed inflammatory status in injured WT muscle and analyzed the consequences on new myofiber growth. Local delivery of IL-10 early after WT muscle injury (2 and 4 d after CTX injection, when proinflammatory cytokine expression is predominant) reduced the CSA of newly forming fibers measured at 7 d after injury compared with saline-treated contralateral damaged muscle (Fig. 4 A). As a control, no reduction of myofiber CSA was observed after IGF-1 (insulin-like growth factor 1) administration. These in vivo results were complemented with two ex vivo satellite cell–based models. Treatment with IL-10 was found to reverse the proproliferative effect of TNF on cultured satellite cells, as shown by BrdU incorporation (Fig. 4 B, left) and cell counting (after 5 d in culture, TNF increased the number of satellite cells by 25 ± 3.5% over WT numbers), whereas TNF/IL-10 co-stimulation did not have a proproliferative effect. Conversely, the differentiation-promoting effect of IL-10 on satellite cells, as shown by enhanced Myogenin and muscle creatine kinase (MCK) expression, was abolished by cotreatment with TNF (Fig. 4 B, right). Finally, in isolated single myofibers from adult mouse muscle, the simultaneous addition of TNF and IL-10 for 72 h reduced the number of Myogenin+ satellite cells per fiber (Fig. 4 C). Thus, timely, sequential expression of pro- and antiinflammatory cytokines produced by specific macrophage subsets appears critical to allow, first, satellite cell proliferation and, later, their differentiation and fusion into myofibers. Consistent with this, premature initiation of the antiinflammatory cytokine program in injured WT muscle with IL-10 (mimicking MKP-1 loss) led to inefficient tissue healing.

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