The cardiac lymphatic system stimulates resolution of inflammation following myocardial infarction
Joaquim Miguel Vieira, … , David G. Jackson, Paul R. Riley
Joaquim Miguel Vieira, … , David G. Jackson, Paul R. Riley
Published July 9, 2018
Citation Information: J Clin Invest. 2018;128(8):3402-3412. https://doi.org/10.1172/JCI97192.
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Research Article Inflammation Vascular biology

The cardiac lymphatic system stimulates resolution of inflammation following myocardial infarction

Abstract

Myocardial infarction (MI) arising from obstruction of the coronary circulation engenders massive cardiomyocyte loss and replacement by non-contractile scar tissue, leading to pathological remodeling, dysfunction, and ultimately heart failure. This is presently a global health problem for which there is no effective cure. Following MI, the innate immune system directs the phagocytosis of dead cell debris in an effort to stimulate cell repopulation and tissue renewal. In the mammalian adult heart, however, the persistent influx of immune cells, coupled with the lack of an inherent regenerative capacity, results in cardiac fibrosis. Here, we reveal that stimulation of cardiac lymphangiogenesis with VEGF-C improves clearance of the acute inflammatory response after MI by trafficking immune cells to draining mediastinal lymph nodes (MLNs) in a process dependent on lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1). Deletion of Lyve1 in mice, preventing docking and transit of leukocytes through the lymphatic endothelium, results in exacerbation of chronic inflammation and long-term deterioration of cardiac function. Our findings support targeting of the lymphatic/immune cell axis as a therapeutic paradigm to promote immune modulation and heart repair.

Authors

Joaquim Miguel Vieira, Sophie Norman, Cristina Villa del Campo, Thomas J. Cahill, Damien N. Barnette, Mala Gunadasa-Rohling, Louise A. Johnson, David R. Greaves, Carolyn A. Carr, David G. Jackson, Paul R. Riley

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Figure 3

LYVE-1 is required for immune cell clearance after MI.

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LYVE-1 is required for immune cell clearance after MI. (A and B) CD68 (g...
(A and B) CD68 (green) immunostaining of sections derived from control and Lyve1–/– intact hearts, documenting the presence of resident macrophages throughout the myocardium of mutant hearts, compared with controls. DAPI (blue) labels cell nuclei. (C) Quantification of resident macrophages (CD45+CD11b+Ly6G–F4/80+) in the intact adult heart by flow cytometry. Data are presented as mean ± SEM; control, n = 4 hearts; Lyve1–/–, n = 4 hearts. No significant differences were observed (unpaired, 2-tailed Student’s t test). (D and E) Whole-mount immunostaining for VEGFR-3 (red) revealing comparable superficial lymphatic networks with lymphangiogenic capillary tips in control and Lyve1–/– hearts on day 7 after MI. (F and G) Vegfc and Ccl21 expression analysis by qRT-PCR showing no differences in expression levels in control and Lyve1–/– hearts on day 7 after MI. Data are presented as mean ± SEM; control, n = 4 hearts; Lyve1–/–, n = 6 hearts. (H–L) Characterization of the immune cell content in control and Lyve1–/– hearts collected on day 7 after MI and analyzed by flow cytometry using antibodies against CD45 (pan-leukocyte marker), CD11b (CD45+CD11b+, myeloid cells), Ly6G (CD45+CD11b+Ly6G+, neutrophils), F4/80 (CD45+CD11b+Ly6G–F4/80+, macrophages), and CD11c (CD45+CD11b+Ly6G–F4/80–CD11c+, dendritic cells). Data are presented as mean ± SEM; control, n = 7 hearts; Lyve1–/–, n = 5 hearts. Significant differences were calculated using an unpaired, 2-tailed Student’s t test (*P ≤ 0.05, **P ≤ 0.01). (M–P) CD68 (green) and TUNEL (red) immunostaining of sections derived from control (M and N) and Lyve1–/– (O and P) hearts on day 7 after MI. (N and P) Magnified views of boxes shown in M and O. DAPI (blue) labels cell nuclei. White arrowheads mark rare macrophages undergoing apoptosis (CD68+TUNEL+). Note increased CD68 expression in Lyve1–/– compared with controls. Scale bars: A, B, M, and O, 100 μm; D and E, 200 μm; N and P, 20 μm.