B cell subsets contribute to myocardial protection by inducing neutrophil apoptosis after ischemia and reperfusion
Fangyang Huang, Jialiang Zhang, Hao Zhou, Tianyi Qu, Yan Wang, Kexin Jiang, Yutong Liu, Yuanning Xu, Mao Chen, Li Chen
Fangyang Huang, Jialiang Zhang, Hao Zhou, Tianyi Qu, Yan Wang, Kexin Jiang, Yutong Liu, Yuanning Xu, Mao Chen, Li Chen
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Research Article Cardiology Immunology

B cell subsets contribute to myocardial protection by inducing neutrophil apoptosis after ischemia and reperfusion

Abstract

A robust, sterile inflammation underlies myocardial ischemia and reperfusion injury (MIRI). Several subsets of B cells possess the immunoregulatory capacity that limits tissue damage, yet the role of B cells in MIRI remains elusive. Here, we sought to elucidate the contribution of B cells to MIRI by transient ligation of the left anterior descending coronary artery in B cell–depleted or –deficient mice. Following ischemia and reperfusion (I/R), regulatory B cells are rapidly recruited to the heart. B cell–depleted or –deficient mice exhibited exacerbated tissue damage, adverse cardiac remodeling, and an augmented inflammatory response after I/R. Rescue and chimeric experiments indicated that the cardioprotective effect of B cells was not solely dependent on IL-10. Coculture experiments demonstrated that B cells induced neutrophil apoptosis through contact-dependent interactions, subsequently promoting reparative macrophage polarization by facilitating the phagocytosis of neutrophils by macrophages. The in vivo cardioprotective effect of B cells was undetectable in the absence of neutrophils after I/R. Mechanistically, ligand-receptor imputation identified FCER2A as a potential mediator of interactions between B cells and neutrophils. Blocking FCER2A on B cells resulted in a reduction in the percentage of apoptotic neutrophils, contributing to the deterioration of cardiac remodeling. Our findings unveil a potential cardioprotective role of B cells in MIRI through mechanisms involving FCER2A, neutrophils, and macrophages.

Authors

Fangyang Huang, Jialiang Zhang, Hao Zhou, Tianyi Qu, Yan Wang, Kexin Jiang, Yutong Liu, Yuanning Xu, Mao Chen, Li Chen

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Figure 10

The identification of the molecule on B cells that induced neutrophil apoptosis.

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The identification of the molecule on B cells that induced neutrophil ap...
(A) tSNE plot from the pooled single-cell RNA sequencing of noncardiomyocyte cells from hearts at 1 and 3 days after myocardial ischemia. (B) Dot plot visualization of the top 5 different marker genes in each cluster. Dot size represents the percentage of expression per cluster; color gradient represents average expression levels per cell. (C) The chord diagram shows the significant inferred interaction from the source cell type (i.e., B cells) with the target cell type (i.e., neutrophils). The arrow thickness is proportional to the calculated communication probability. (D) FCER2A expression levels on circulating B cells of sham-operated or post-I/R mice. (E) CD18 expression levels on neutrophils in heart of sham-operated or post-I/R mice. (F) Representative flow cytometry images for the detection and quantification of apoptotic neutrophils in each group. In the presence of LPS (100 ng/mL), freshly isolated neutrophils were cultured for 12 hours with or without B cells that were preincubated with anti-CD22 (10 μg/mL), anti-FCER2A (10 μg/mL), or vehicle. (G) The violin plot shows Fcer2a expression levels in each cluster after myocardial ischemia. (H) Mice were injected with anti-FCER2A antibody (150 μg per mouse, i.p.) or isotype immediately after I/R. The apoptotic neutrophils from hearts were detected by flow cytometry 3 days after myocardial ischemia. The percentage of annexin V+ neutrophils was quantified. (I) Representative images of immunofluorescent staining show the interaction between Ly6G+ neutrophils and CD19+ B cells in heart sections of mice 3 days after MIRI. The experiments were independently replicated twice. Scale bars: 50 μm. Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 by 1-way ANOVA test followed by Tukey’s post hoc test (D, E, I, and H); differences between 2 groups were compared by unpaired, 2-tailed t test (F). αFCER2A, anti-FCER2A antibody; FMO, fluorescence minus one; I/R, ischemia and reperfusion.