Key result
MUG1 reduces Lgals3-driven neutrophil degranulation by ~64% and their ratio correlates with post-MI wall thickness.
Why the study?
While neutrophil to macrophage communication after myocardial infarction has been explored, macrophage-to-neutrophil communication has been understudied.
p-value: p=<0.001
Macrophage-secreted MUG1 and Lgals3 have opposing effects on neutrophil degranulation after myocardial infarction, playing a key role in regulating infarct wall thinning.
Inflammation presides early after myocardial infarction (MI) as a key event in cardiac wound healing. Ischemic cardiomyocytes secrete inflammatory cues to stimulate infiltration of leukocytes, predominantly macrophages and neutrophils. Infiltrating neutrophils degranulate to release a series of proteases including matrix metalloproteinase (MMP)-9 to break down extracellular matrix and remove necrotic myocytes to create space for the infarct scar to form. While neutrophil to macrophage communication has been explored, the reverse has been understudied. We used a proteomics approach to catalogue the macrophage secretome at MI day 1. Murinoglobulin-1 (MUG1) was the highest-ranked secreted protein (4.1-fold upregulated at MI day 1 vs. day 0 pre-MI cardiac macrophages, p = 0.004). By transcriptomics evaluation, galectin-3 (Lgals3) was 2.2-fold upregulated (p = 0.008) in MI day 1 macrophages. We explored the direct roles of MUG1 and Lgals3 on neutrophil degranulation. MUG1 blunted while Lgals3 amplified neutrophil degranulation in response to phorbol 12-myristate 13-acetate or interleukin-1β, as measured by MMP-9 secretion. Lgals3 itself also stimulated MMP-9 secretion. To determine if MUG1 regulated Lgals3, we co-stimulated neutrophils with MUG1 and Lgals3. MUG1 limited degranulation stimulated by Lgals3 by 64% (p < 0.001). In vivo, MUG1 was elevated in the infarct region at MI days 1 and 3, while Lgals3 increased at MI day 7. The ratio of MUG1 to Lgals3 positively correlated with infarct wall thickness, revealing that MUG1 attenuated infarct wall thinning. In conclusion, macrophages at MI day 1 secrete MUG1 to limit and Lgals3 to accentuate neutrophil degranulation to regulate infarct wall thinning.
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Chalise et al. (2022) studied Myocardial infarction. MUG1 and Lgals3 was evaluated on Neutrophil degranulation (MMP-9 secretion) (p=<0.001). MUG1 limited neutrophil degranulation stimulated by Lgals3 by 64% (p<0.001), and their in vivo ratio positively correlated with infarct wall thickness after myocardial infarction.
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