Fibroblast-specific IKK-β deficiency ameliorates angiotensin II–induced adverse cardiac remodeling in mice
Weiwei Lu, Zhaojie Meng, Rebecca Hernandez, Changcheng Zhou
Weiwei Lu, Zhaojie Meng, Rebecca Hernandez, Changcheng Zhou
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Research Article Cardiology

Fibroblast-specific IKK-β deficiency ameliorates angiotensin II–induced adverse cardiac remodeling in mice

Abstract

Cardiac inflammation and fibrosis contribute significantly to hypertension-related adverse cardiac remodeling. IκB kinase β (IKK-β), a central coordinator of inflammation through activation of NF-κB, has been demonstrated as a key molecular link between inflammation and cardiovascular disease. However, the cell-specific contribution of IKK-β signaling toward adverse cardiac remodeling remains elusive. Cardiac fibroblasts are one of the most populous nonmyocyte cell types in the heart that play a key role in mediating cardiac fibrosis and remodeling. To investigate the function of fibroblast IKK-β, we generated inducible fibroblast-specific IKK-β–deficient mice. Here, we report an important role of IKK-β in the regulation of fibroblast functions and cardiac remodeling. Fibroblast-specific IKK-β–deficient male mice were protected from angiotensin II–induced cardiac hypertrophy, fibrosis, and macrophage infiltration. Ablation of fibroblast IKK-β inhibited angiotensin II–stimulated fibroblast proinflammatory and profibrogenic responses, leading to ameliorated cardiac remodeling and improved cardiac function in IKK-β–deficient mice. Findings from this study establish fibroblast IKK-β as a key factor regulating cardiac fibrosis and function in hypertension-related cardiac remodeling.

Authors

Weiwei Lu, Zhaojie Meng, Rebecca Hernandez, Changcheng Zhou

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Figure 8

Deficiency of fibroblast IKK-β reduces angiotensin II–elicited cardiac macrophage infiltration.

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Deficiency of fibroblast IKK-β reduces angiotensin II–elicited cardiac m...
(A and B) Eight-week-old male IKKβfl/fl and IKKβΔFib mice were i.p. injected with 2 mg tamoxifen per day for 5 days. At the age of 10 weeks, those mice were infused with 1000 ng/kg/min of angiotensin II (Ang II) or vehicle control for 1 week. qPCR analysis of the mRNA levels of macrophage markers in the hearts of IKKβfl/fl and IKKβΔFib mice (n = 5, 2-way ANOVA; **P < 0.01 and ***P < 0.001) (A). Representative images of immunofluorescence staining (left) and the quantification (right) of CD68 in the hearts of IKKβfl/fl and IKKβΔFib mice (n = 3–4, 2-way ANOVA; **P < 0.01; scale bar: 50 μm). The nuclei were visualized with DAPI (blue) (B). (C) Cardiac fibroblasts (CFs) were isolated from IKKβfl/fl or IKKβΔFib mice and pretreated with 10–6 M of Ang II for 24 hours. CFs were cocultured with calcein acetoxymethyl–labeled peritoneal macrophages (PMs) from IKKβfl/fl mice for 2 hours. Adhered PMs were counted under a fluorescence microscope. Representative images (left) and the quantification (right) of adhered PMs were presented (n = 3; 2-way ANOVA; **P < 0.01, ***P < 0.001; scale bar: 200 μm). (D) PMs of IKKβfl/fl mice were seeded on the Matrigel-coated Transwell filters for 24 hours. The lower chambers were filled with the conditioned medium from cultured control or IKK-β–deficient CFs treated with vehicle control or 10–6 M of Ang II. PMs that infiltrated and migrated to the underside of Transwells were stained with hematoxylin and counted under the microscope. Representative images (left) and the quantification (right) of migrated PMs (n = 3, 2-way ANOVA; ***P < 0.001; scale bar: 100 μm). (E) PMs isolated from IKKβfl/fl were treated with conditioned medium from cultured control or IKK-β–deficient CFs treated with vehicle control or 10–6 M of Ang II. qPCR analysis was performed to measure the mRNA levels of inflammatory cytokines and adhesion molecules (n = 3, 2-way ANOVA; *P < 0.05, **P < 0.01, and ***P < 0.001).