. 2017 Jan 4;25(1):192-204.

doi: 10.1016/j.ymthe.2016.09.001. Epub 2017 Jan 4.

Macrophage-Derived mir-155-Containing Exosomes Suppress Fibroblast Proliferation and Promote Fibroblast Inflammation during Cardiac Injury

Chunxiao Wang¹, Congcong Zhang¹, Luxin Liu¹, Xi A¹, Boya Chen¹, Yulin Li², Jie Du³

Affiliations

¹ Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China; The Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing 100029, China; Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Collaborative Innovative Research Center for Cardiovascular Diseases, Beijing 100029, China.
² Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China; The Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing 100029, China; Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Collaborative Innovative Research Center for Cardiovascular Diseases, Beijing 100029, China. Electronic address: lyllyl_1111@163.com.
³ Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China; The Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing 100029, China; Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Collaborative Innovative Research Center for Cardiovascular Diseases, Beijing 100029, China. Electronic address: jdu@bcm.edu.

PMID: 28129114
PMCID: PMC5363311
DOI: 10.1016/j.ymthe.2016.09.001

Macrophage-Derived mir-155-Containing Exosomes Suppress Fibroblast Proliferation and Promote Fibroblast Inflammation during Cardiac Injury

Chunxiao Wang et al. Mol Ther. 2017.

. 2017 Jan 4;25(1):192-204.

doi: 10.1016/j.ymthe.2016.09.001. Epub 2017 Jan 4.

Authors

Chunxiao Wang¹, Congcong Zhang¹, Luxin Liu¹, Xi A¹, Boya Chen¹, Yulin Li², Jie Du³

Affiliations

¹ Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China; The Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing 100029, China; Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Collaborative Innovative Research Center for Cardiovascular Diseases, Beijing 100029, China.
² Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China; The Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing 100029, China; Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Collaborative Innovative Research Center for Cardiovascular Diseases, Beijing 100029, China. Electronic address: lyllyl_1111@163.com.
³ Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China; The Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Beijing 100029, China; Beijing Institute of Heart Lung and Blood Vessel Diseases, Beijing Collaborative Innovative Research Center for Cardiovascular Diseases, Beijing 100029, China. Electronic address: jdu@bcm.edu.

PMID: 28129114
PMCID: PMC5363311
DOI: 10.1016/j.ymthe.2016.09.001

Abstract

Inflammation plays an important role in cardiac injuries. Here, we examined the role of miRNA in regulating inflammation and cardiac injury during myocardial infarction. We showed that mir-155 expression was increased in the mouse heart after myocardial infarction. Upregulated mir-155 was primarily presented in macrophages and cardiac fibroblasts of injured hearts, while pri-mir-155 was only expressed in macrophages. mir-155 was also presented in exosomes derived from macrophages, and it can be transferred into cardiac fibroblasts by macrophage-derived exosomes. A mir-155 mimic or mir-155 containing exosomes inhibited cardiac fibroblast proliferation by downregulating Son of Sevenless 1 expression and promoted inflammation by decreasing Suppressor of Cytokine Signaling 1 expression. These effects were reversed by the addition of a mir-155 inhibitor. In vivo, mir-155-deficient mice showed a significant reduction of the incidence of cardiac rupture and an improved cardiac function compared with wild-type mice. Moreover, transfusion of wild-type macrophage exosomes to mir-155^-/- mice exacerbated cardiac rupture. Finally, the mir-155-deficient mice exhibited elevated fibroblast proliferation and collagen production, along with reduced cardiac inflammation in injured heart. Taken together, our results demonstrate that activated macrophages secrete mir-155-enriched exosomes and identify macrophage-derived mir-155 as a paracrine regulator for fibroblast proliferation and inflammation; thus, a mir-155 inhibitor (i.e., mir-155 antagomir) has the potential to be a therapeutic agent for reducing acute myocardial-infarction-related adverse events.

Keywords: cardiac fibroblast; inflammation; mir-155; myocardial infarction; proliferation.

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Figures

**Figure 1**
The mir-155 Expression Is Increased in Heart after AMI (A) Shown is qRT-PCR analysis of mir-155 relative folds to U6 expression in the infarcted heart 7 days after myocardial infarction (MI) (n = 3 per group). Data are mean ± SEM. Paired t test was used. **p < 0.01 versus Sham operation. (B) qRT-PCR shows the mir-155 relative folds to U6 expression in cardiomyocytes (CM), cardiac fibroblasts (CF), and macrophages (Mφ) isolated from the sham-operated and infarcted hearts (n = 3 per group). Data are mean ± SEM. Paired t test was used.*p < 0.05 versus Sham. ^$p < 0.05 versus Sham operation. (C) Shown is the pri-mir-155 relative folds to GAPDH in cardiomyocytes (CM), cardiac fibroblasts (CF), and macrophages (Mφ) isolated from the sham-operated and infarcted hearts (n = 3 per group). Data are mean ± SEM. Paired t test was used. **p < 0.01 versus Sham operation.

**Figure 2**
Activated Macrophages Secrete Exosomes that Are Taken up by Cardiac Fibroblasts (A) Flow chart depicts the differential centrifugation protocol. Macrophages were first stimulated by lipopolysaccharide (LPS) or Ang II for 24 hr. Exosomes were then collected by differential centrifugation. (B) Shown are the representative Electron microscopy pictures for exosomes isolated from macrophage stimulated by PBS, LPS, or AngII. Scale bar, 1 nm. (C) Representative western blotting shows the exosome marker Alix, macrophage marker CD68, Endoplasmic reticulum (ER) marker Grp94 and calnexin, Golgi marker GM130, Mitochondria marker cytochrome c (CYC1), Nucleus marker histones (HIST*H*), and Argonaute/RISC complex marker AGO on macrophages and exosomes isolated from macrophage stimulated by PBS, LPS, or AngII. (D) RNA content of the same protein amount of exosomes derived from macrophage stimulated with PBS, LPS, or AngII (n = 3 per group). *p < 0.05 versus exosome derived from PBS-treated macrophage. (E) Shown are confocal images of macrophages stained with DilC₁₆3, a phospholipid membrane dye (top), and cardiac fibroblasts after incubation with exosomes from stained macrophage for 48 hr (bottom). Scale bar, 10 μm.

**Figure 3**
Macrophage-Secreted mir-155 Can Be Transferred into Cardiac Fibroblasts (A) qRT-PCR shows the relative folds of mir-155 to U6 expression in macrophage and macrophage-secreted exosomes stimulated with LPS or Ang II (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus PBS. ^$p < 0.05 versus exosome isolated from PBS-treated macrophages. (B) The mir-155 relative folds to U6 expression in 1 × 10⁵ cardiac fibroblasts co-cultured with exosomes (40 μg/ml) isolated from PBS or Ang-II-stimulated macrophages (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus CF+exo^PBS-Mφ. (C) The relative folds of pri-mir-155 expression to GAPDH in cardiac fibroblasts co-cultured with exosomes isolated from PBS or Ang-II-stimulated macrophages (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus CF+exo^PBS-Mφ. (D) mir-155 relative folds to U6 expression are detected by qRT-PCR in WT cardiac fibroblasts co-cultured with the supernatant of AngII-stimulated WT macrophages and the supernatant of AngII-stimulated mir-155 deficiency (mir-155^−/−) macrophages that were stimulated by Ang II for 48 hr (n = 3 per group). Data are mean ± SEM. Paired t test was used. **p < 0.01 versus Ang II. (E) qRT-PCR shows the mir-155 relative folds to U6 expression in WT cardiac fibroblasts co-cultured with the supernatant of WT macrophage stimulated by Ang II for 24 hr or exosome-depleted macrophage supernatant (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus basal medium. ^$p < 0.05 versus Mφ supernatant. (F) qRT-PCR analysis of mir-155 relative folds to U6 expression in mir-155^−/− cardiac fibroblasts after respectively incubation with exosomes from PBS or Ang-II-stimulated WT macrophages or exosomes from Ang-II-stimulated mir-155^−/− macrophages (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus exo^{PBS-WT Mφ}. ^$p < 0.05 versus exo^{Ang II-WT Mφ}.

**Figure 4**
mir-155-Containing Macrophage Exosomes Suppress the Proliferation of Recipient Cardiac Fibroblasts by Downregulating Sos1 Protein (A) Go and Pathway analysis were performed on mir-155 target genes predicted by TargetScan base. (B) Shown is the BrdU staining and quantification of BrdU positive cells of cardiac fibroblasts treated with mir-155 mimic or control mimic RNAs for 48 hr (n = 3 per group). *p < 0.05 versus control mimic. Scale bar, 100 nm. (C) Shown is quantification of BrdU staining of cardiac fibroblasts treated with exosomes isolated from PBS or Ang-II-stimulated WT macrophages or exosomes from Ang-II-stimulated mir-155^−/− macrophages (n = 3 per group). *p < 0.05 versus exo^{PBS-WT Mφ}. ^$p < 0.05 versus exo^{Ang II-Mφ}. (D) Shown is BrdU staining of WT exosomes-treated cardiac fibroblasts transfected with control inhibitor or mir-155 inhibitor (n = 3 per group). *p < 0.05 versus PBS. ^$p < 0.05 versus fibroblast treated with exo^{Ang II-Mφ} and control inhibitor. (E) The predicted mir-155 seed sequence in the Sos1 3′-UTR region is shown. (F) The graph shows the effect of mir-155 on wild-type and mutated Sos1 luciferase reporter assay (n = 3 per group). *p < 0.05 versus control mimic. (G) Western blotting analysis and quantification of Sos1 protein level in lysates of cardiac fibroblasts transfected with mir-155 mimic or control mimic RNAs (n = 3 per group). *p < 0.05 versus control mimic. (H) qRT-PCR analysis of Sos1 relative folds to GAPDH in cardiac fibroblasts stimulated with PBS or Ang II is shown (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus PBS. (I) Western blotting analysis and quantification of Sos1 protein level of cardiac fibroblasts transfected with si-control or si-Sos1 (n = 3 per group). *p < 0.05 versus si-control. (J) Representative images of BrdU positive cells of cardiac fibroblasts transfected with si-control or si-Sos1 (right panel). Bar graph shows quantification of BrdU positive cells (left panel) (n = 3 per group). *p < 0.05 versus si-control. Scale bar, 100 nm.

**Figure 5**
mir-155-Containing Macrophage Exosome Aggravates Fibroblasts Inflammation by Regulation of Socs1/Stat3 Signaling (A and B) Respectively showed the mRNA (A) and protein (B) level of IL-1β, IL-6, TNF-α, and CCL2 expression in cardiac fibroblasts transfected with control mimic or mir-155 mimic (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus control mimic. (C) Representative western blotting images and quantification of Socs1, phosphorylated Stat3 (p-Stat3), and total Stat3 (t-Stat3) in cardiac fibroblasts transfected with control mimic or mir-155 mimic (n = 3 per group). *p < 0.05 versus control mimic. (D and E) Shown are the mRNA and protein level of IL-1β, IL-6, TNF-α, and CCL2 in WT exosomes-treated cardiac fibroblasts with or without mir-155 inhibitor (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus PBS. ^$p < 0.05 versus fibroblast treated with exo^{Ang II-Mφ} and control inhibitor.

**Figure 6**
mir-155 and mir-155-Containing Exosomes Led to Cardiac Rupture and Adverse Prognosis of Myocardial Infarction (A) Survival curves of WT mice and mir-155^−/− mice after AMI (n = 60 for WT mice and n = 48 for mir-155^−/− mice) *p < 0.05 versus WT. (B) Prevalence of death caused by cardiac rupture after AMI (n = 60 for WT mice and n = 48 for mir-155^−/− mice). (C) Representative Masson trichrome staining and immunohistochemical staining of Collagen I and α-SMA on infarcted area of WT and mir-155^−/− heart tissue 7 days after AMI (n = 9 per group). Scale bar, 100 nm. (D) Quantification of fibrosis, the ratio of α-SMA positive staining and Collagen I positive staining to total myocardial tissue (n = 9 per group). *p < 0.05 versus WT mice after MI. (E) qRT-PCR showed the relative folds of α-SMA, Collagen I, and Collagen III to GAPDH on infarcted heart of WT and mir-155^−/− mice (n = 9 for WT mice and n = 11 for mir-155^−/− mice). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus WT Sham. ^$p < 0.05 versus WT mice after MI. (F) Shown are LVEF, LVFS, LVEDD, and LVESD of WT and mir-155^−/− mice 7 days after AMI by echocardiography analysis. *p < 0.05 versus WT mice after MI. (G) Flow chart depicting the transfusion experiment design. (H) Shown is the mir-155 relative folds to U6 expression in the heart of mir-155^−/− mice transfused with saline, mir-155^−/− Mφ-secreted exosomes (200 μg) and WT Mφ-secreted exosomes (100 or 200 μg) (n = 3 for mir-155^−/− mice transfected with saline or exo^{KO Mφ}-200 μg, n = 4 for mir-155^−/− transfected with exo^WT Mφ). *p < 0.05 versus mir-155^−/− mice transfected with exo^{KO Mφ}-200 μg. (I) Prevalence of death because of cardiac rupture after acute myocardial infarction in mir-155^−/− mice transfused with saline, mir-155^−/− Mφ-secreted exosomes (200 μg), or WT Mφ-secreted exosomes (100 or 200 μg). (J) Shown is Masson trichrome staining and quantification of fibrosis on infarcted area of saline, mir-155^−/− Mφ-secreted exosomes (200 μg) or WT Mφ-secreted exosomes (100 or 200 μg) transfused heart tissue 7 days after AMI (n = 3 for mir-155^−/− mice transfected with saline or exo^{KO Mφ}-200 μg, n = 4 for mir-155^−/− transfected with exo^WT Mφ). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus mir-155^−/− mice transfected with exo^{KO Mφ}-200 μg. Scale bar, 100 nm.

**Figure 7**
mir-155 Deficiency Increases Fibroblasts Proliferation and Decreases Inflammation (A) Western blotting analysis and quantification of Sos1 expression in the heart of infarcted WT and mir-155^−/− mice (n = 9 per group). *p < 0.05 versus WT mice after MI. (B) Shown is BrdU staining and quantification of BrdU positive cells of proliferative cells in infarcted heart (n = 3 per group). *p < 0.05 versus WT mice after MI. Scale bar, 100 nm. (C) Western blotting analysis and quantification of Socs1 expression in the heart of infarcted WT and mir-155^−/− mice (n = 9 per group). *p < 0.05 versus WT mice after MI. (D) Shown are H&E staining on the infarcted area of WT and mir-155^−/− heart tissue 7 days after AMI (n = 9 per group). Scale bar, 100 nm. (E) Real-time PCR analysis of IL-1β, IL-6, TNF-α, and CCL-2 mRNA levels in WT and mir-155^−/− mouse hearts (n = 9 for WT mice and n = 11 for mir-155^−/− mice). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus WT mice after MI. (F) Western blotting analysis and quantification of Sos1 and Socs1 expression in the heart of mir-155^−/− mice transfused with AngII-stimulated mir-155^−/− Mφ-secreted exosomes (exo^{AngII-KO Mφ}) or AngII-stimulated WT Mφ-secreted exosomes (exo^{AngII-WT Mφ}). n = 3 per group. *p < 0.05 versus exo^{AngII-KO Mφ}. (G) Shown is the IL-1β, IL-6, TNF-α, and CCL2 relative folds to GAPDH expression in the heart of mir-155^−/− mice transfused with AngII-stimulated mir-155^−/− Mφ-secreted exosomes (exo^{AngII-KO Mφ}) or AngII-stimulated WT Mφ-secreted exosomes (exo^{AngII-WT Mφ}) (n = 3 per group). Data are mean ± SEM. Paired t test was used. *p < 0.05 versus exo^{AngII-KO Mφ}.

**Figure 8**
Summarize the Role of mir-155-Containing Mφ Exosomes on Cardiac Fibroblasts Proliferation and Inflammation During cardiac injury, activated macrophages secrete mir-155-enriched exosomes that are transported into cardiac fibroblasts. Macrophage-derived mir-155 suppresses proliferation and promotes inflammation of fibroblast, which leads to cardiac rupture after AMI.

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References

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Macrophage-Derived mir-155-Containing Exosomes Suppress Fibroblast Proliferation and Promote Fibroblast Inflammation during Cardiac Injury

Affiliations

Macrophage-Derived mir-155-Containing Exosomes Suppress Fibroblast Proliferation and Promote Fibroblast Inflammation during Cardiac Injury

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