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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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p38–MKP-1 balance is required for efficient skeletal muscle repair. (A) Number of F4/80-positive macrophages in WT muscle at the indicated times postinjury (P.I.) that were obtained by flow cytometry. Total number of cells per milligram of CTX-injured muscle tissue was calculated. (B) Phospho-p38– and phospho–c-Jun (as an indicator of activated JNK)–positive macrophages (P-p38 and P-cJun, respectively) were counted in immunostained cryosections of gastrocnemius muscles obtained from WT mice 3, 6, and 10 d after injury (see pictures in Fig. S1 C). (C) Gene expression analysis by RT-PCR in isolated macrophage populations at the indicated times after injury. (D) As in A, number of F4/80-positive macrophages in WT and MKP-1−/− mice per milligram of injured muscle tissue. (E) As in B, phospho-p38– and phospho–c-Jun–positive macrophages from WT and MKP-1−/− mice at the indicated times after injury (see pictures in Fig. S1 C). (F) Muscle cryosections were stained with an anti-eMHC antibody. Bar, 50 µm. (G) As in F, cryosections were stained with H/E, and the mean area of regenerating myofibers was calculated (see pictures in Fig. S1). Means ± SEM of at least three experiments. ***, P < 0.001; **, P < 0.01; *, P < 0.05.
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fig1: p38–MKP-1 balance is required for efficient skeletal muscle repair. (A) Number of F4/80-positive macrophages in WT muscle at the indicated times postinjury (P.I.) that were obtained by flow cytometry. Total number of cells per milligram of CTX-injured muscle tissue was calculated. (B) Phospho-p38– and phospho–c-Jun (as an indicator of activated JNK)–positive macrophages (P-p38 and P-cJun, respectively) were counted in immunostained cryosections of gastrocnemius muscles obtained from WT mice 3, 6, and 10 d after injury (see pictures in Fig. S1 C). (C) Gene expression analysis by RT-PCR in isolated macrophage populations at the indicated times after injury. (D) As in A, number of F4/80-positive macrophages in WT and MKP-1−/− mice per milligram of injured muscle tissue. (E) As in B, phospho-p38– and phospho–c-Jun–positive macrophages from WT and MKP-1−/− mice at the indicated times after injury (see pictures in Fig. S1 C). (F) Muscle cryosections were stained with an anti-eMHC antibody. Bar, 50 µm. (G) As in F, cryosections were stained with H/E, and the mean area of regenerating myofibers was calculated (see pictures in Fig. S1). Means ± SEM of at least three experiments. ***, P < 0.001; **, P < 0.01; *, P < 0.05.

Mentions: In response to injury, two subsets of macrophages are sequentially present in regenerating skeletal muscle. In acute injury models, damaged tissue first recruits Ly-6Chigh monocytes/macrophages that exhibit a proinflammatory cytokine activation profile, whereas at later stages, macrophages within muscle switch their phenotype to become predominantly Ly-6Clow, showing an antiinflammatory profile (Arnold et al., 2007). To determine whether the p38–MKP-1 inflammatory pathway is involved in this regenerative response to tissue injury, we characterized by cell sorting (FACS) the different macrophage populations present in muscle of wild-type (WT) mice (by cell number and activation profile) after injection of cardiotoxin (CTX) and analyzed their p38–MKP-1 activity over time. As shown in Fig. 1 A, proinflammatory Ly-6Chigh macrophages constituted the predominant population from day 1 to 3, decreasing thereafter. At later time points, Ly-6Clow macrophages were the most abundant, but their number was progressively reduced, paralleling tissue healing (Fig. 1 A).


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)

p38–MKP-1 balance is required for efficient skeletal muscle repair. (A) Number of F4/80-positive macrophages in WT muscle at the indicated times postinjury (P.I.) that were obtained by flow cytometry. Total number of cells per milligram of CTX-injured muscle tissue was calculated. (B) Phospho-p38– and phospho–c-Jun (as an indicator of activated JNK)–positive macrophages (P-p38 and P-cJun, respectively) were counted in immunostained cryosections of gastrocnemius muscles obtained from WT mice 3, 6, and 10 d after injury (see pictures in Fig. S1 C). (C) Gene expression analysis by RT-PCR in isolated macrophage populations at the indicated times after injury. (D) As in A, number of F4/80-positive macrophages in WT and MKP-1−/− mice per milligram of injured muscle tissue. (E) As in B, phospho-p38– and phospho–c-Jun–positive macrophages from WT and MKP-1−/− mice at the indicated times after injury (see pictures in Fig. S1 C). (F) Muscle cryosections were stained with an anti-eMHC antibody. Bar, 50 µm. (G) As in F, cryosections were stained with H/E, and the mean area of regenerating myofibers was calculated (see pictures in Fig. S1). Means ± SEM of at least three experiments. ***, P < 0.001; **, P < 0.01; *, P < 0.05.
© Copyright Policy - openaccess
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3198158&req=5

fig1: p38–MKP-1 balance is required for efficient skeletal muscle repair. (A) Number of F4/80-positive macrophages in WT muscle at the indicated times postinjury (P.I.) that were obtained by flow cytometry. Total number of cells per milligram of CTX-injured muscle tissue was calculated. (B) Phospho-p38– and phospho–c-Jun (as an indicator of activated JNK)–positive macrophages (P-p38 and P-cJun, respectively) were counted in immunostained cryosections of gastrocnemius muscles obtained from WT mice 3, 6, and 10 d after injury (see pictures in Fig. S1 C). (C) Gene expression analysis by RT-PCR in isolated macrophage populations at the indicated times after injury. (D) As in A, number of F4/80-positive macrophages in WT and MKP-1−/− mice per milligram of injured muscle tissue. (E) As in B, phospho-p38– and phospho–c-Jun–positive macrophages from WT and MKP-1−/− mice at the indicated times after injury (see pictures in Fig. S1 C). (F) Muscle cryosections were stained with an anti-eMHC antibody. Bar, 50 µm. (G) As in F, cryosections were stained with H/E, and the mean area of regenerating myofibers was calculated (see pictures in Fig. S1). Means ± SEM of at least three experiments. ***, P < 0.001; **, P < 0.01; *, P < 0.05.
Mentions: In response to injury, two subsets of macrophages are sequentially present in regenerating skeletal muscle. In acute injury models, damaged tissue first recruits Ly-6Chigh monocytes/macrophages that exhibit a proinflammatory cytokine activation profile, whereas at later stages, macrophages within muscle switch their phenotype to become predominantly Ly-6Clow, showing an antiinflammatory profile (Arnold et al., 2007). To determine whether the p38–MKP-1 inflammatory pathway is involved in this regenerative response to tissue injury, we characterized by cell sorting (FACS) the different macrophage populations present in muscle of wild-type (WT) mice (by cell number and activation profile) after injection of cardiotoxin (CTX) and analyzed their p38–MKP-1 activity over time. As shown in Fig. 1 A, proinflammatory Ly-6Chigh macrophages constituted the predominant population from day 1 to 3, decreasing thereafter. At later time points, Ly-6Clow macrophages were the most abundant, but their number was progressively reduced, paralleling tissue healing (Fig. 1 A).

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