Lymphatic dysfunction and ZFP36 deficiency contribute to myxomatous valve degeneration in Marfan syndrome mice
Can Tan, Ziyou Ren, Shreya Kurup, Xianpeng Liu, Zhi-Dong Ge, Shodai Suzuki, Pritika Jakka, Cheryl Tang, M. Luisa Iruela-Arispe, Tsutomu Kume
Can Tan, Ziyou Ren, Shreya Kurup, Xianpeng Liu, Zhi-Dong Ge, Shodai Suzuki, Pritika Jakka, Cheryl Tang, M. Luisa Iruela-Arispe, Tsutomu Kume
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Research Article Cardiology Development Vascular biology

Lymphatic dysfunction and ZFP36 deficiency contribute to myxomatous valve degeneration in Marfan syndrome mice

Abstract

Enhanced TGF-β signaling caused by mutations in Fibrillin-1 (FBN1) in patients with Marfan syndrome (MFS) leads to myxomatous degeneration of the mitral valve (MDMV). MDMV can result in mitral valve prolapse, severe regurgitation, and sudden cardiac death. However, it remains unknown whether lymphatic vessel (LV) dysfunction contributes to MDMV development in MFS. Here, we show that lymphangiogenesis in murine mitral valves (MVs) begins postnatally. However, this process is inhibited in a mouse MFS model, Fbn1 mutant (Fbn1C1039G/+) mice, accompanied by disrupted lymphatic cell-cell junctions, impaired lymphatic drainage, and an abnormally widespread distribution of MHCII+ infiltrating macrophages. Treatment of Fbn1 mutant mice with VEGF-C156S, a selective VEGFR3 agonist, stimulates the ERK and Akt pathways, increases LV density in MVs, and ameliorates MDMV. Fbn1 mutant MVs display disorganized valvular endothelial cells (VECs) and decreased expression of the antiinflammatory modulator Zfp36 (zinc finger protein 36) in VECs and immune cells. Treatment with FTY720 (fingolimod), a ZFP36 activator and S1P antagonist, rescues MDMV phenotypes in Fbn1 mutant mice by reducing immune cell infiltration and restoring lymphatic cell junctions and drainage. These findings suggest that the Fbn1 mutation causes LV hypoplasia and defective lymphatic drainage in MVs, driven in part by proinflammatory VECs, leading to MFS-related MDMV.

Authors

Can Tan, Ziyou Ren, Shreya Kurup, Xianpeng Liu, Zhi-Dong Ge, Shodai Suzuki, Pritika Jakka, Cheryl Tang, M. Luisa Iruela-Arispe, Tsutomu Kume

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Figure 3

VEGF-C156S promotes lymphatic growth in the MVs and ameliorates MV thickening in Fbn1 mutant mice by activating the ERK and Akt signaling pathways.

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VEGF-C156S promotes lymphatic growth in the MVs and ameliorates MV thick...
(A) Timeline for the VEGF-C156S treatment in B–J. (B) Representative confocal images of whole-mount aLs at P14 under PBS (vehicle control) and VEGF-C156S treatment. Yellow dashed lines indicate the proximal edge of leaflets. Scale bars: 200 μm. (C) Quantification of LV density in aLs based on the data shown in B. Data are mean ± SEM, ordinary 1-way ANOVA, each symbol represents 1 mouse. N = 5-6, male/female = 2:4, 3:3, 3:2, and 3:2 in the WT-PBS, Fbn1-PBS, WT-VEGF-C156S, and Fbn1-VEGF-C156S groups, respectively. **P < 0.01. (D) Resliced 2D images from the 3D image stacks of whole-mount MV leaflets along the midline of each leaflet. Blue dashed line indicates the root of leaflets. Scale bars: 200 μm. (E) Quantification of MV leaflet thickness based on the data shown in D. Data are mean ± SEM, ordinary 1-way ANOVA test for aLs, unpaired 2-tailed Student’s t test for pLs, each symbol represents 1 mouse. N = 5, male/female = 2:3. ***P < 0.001, ****P < 0.0001. (F–J) Representative confocal images of LVs labeled with p-ERK1/2 (F) or p-Akt (I) in the boxed region of aLs at P14 (G) and quantification of fluorescence intensity (FI) of these markers in LECs (H and J). Scale bars: 50 μm (F), 20 μm (I). Data are mean ± SEM in H and J, ordinary 1-way ANOVA, each symbol represents 1 mouse. N = 6-7 in H, male/female = 2:4 in PBS-treated WT, 4:3 in other groups; N = 5-8 in J, 2-5 males and 3 females. *P < 0.05.