RESUMO
【Objective】 To explore the effect of B lymphocytes on cardiac structure and function and myocardial immune cells during heart development. 【Methods】 Echocardiography, immunofluorescence staining and flow cytometry were used to evaluate the composition of immune cells of the heart and the cardiac structure and function in wild-type (WT) mice and B-lymphocyte-deficient (μMT) mice, respectively. 【Results】 Compared with those of μMT mice, the ratio of heart weight to mouse weight (P<0.05), left ventricular mass (P<0.05) and the cross-sectional area of myocardial cells WT mice were significantly increased, while the ventricular ejection fraction was significantly decreased (P<0.05). The results of mRNA sequencing showed that WT mice and μMT mice differentially expressed genes were mainly enriched in the signal pathway of heart development and hypertrophic cardiomyopathy. The results of flow cytometry showed that WT mice had more Ly6g+ neutrophils, CD4+ positive T cells (P<0.001) and CD8+T cells (P<0.05) compared with μMT mice. 【Conclusion】 B-lymphocyte depletion alters the composition of cardiomyocyte immune cells, reduces left ventricular mass, and increases myocardial contractility.
RESUMO
【Objective】 To explore B lymphocytes’ role and mechanisms in angiotensinⅡ/phenylephrine (AngⅡ/PE) induced cardiomyopathy so as to understand the role of inflammatory cells in myocardial injury. 【Methods】 AngⅡ/PE was administered to wild-type (WT) and B cells deficiency (μMT) mice for 14 days or 28 days. The mice were analyzed by blood pressure measurement, echocardiography imaging, flow cytometry, and histology. Cardiac fibrosis was evaluated by Masson staining. 【Results】 Compared with the control group, the left ventricular mass (P<0.01), heart mass/tibia length ratio (P<0.01) and cross-sectional area of cardiomyocytes in AngⅡ/PE group were significantly increased (P<0.01). After 2 weeks of AngⅡ/PE treatment, B lymphocytes (P<0.05), CD45+ leukocytes (P<0.05), CD64-Ly6C+ monocytes (P<0.05), CD64+Ly6C-macrophages (P<0.05) and Ly6g+ neutrophils (P<0.05) were recruited in myocardial tissue. Compared with WT_AngⅡ/PE group, the heart weight/tibia length ratio (P<0.05), left ventricular weight (P<0.05) and myocardial cell cross-sectional area (P<0.05) of μMT_AngⅡ/PE mice were significantly improved. CD45+Ly6C+CD64- monocytes (P<0.05) and CD45+Ly6C-CD64+ macrophages (P<0.05) were significantly decreased. 【Conclusion】 B lymphocytes deficiency improves AngⅡ/PE induced cardiac hypertrophy by reducing the infiltration of CD45+Ly6C+CD64- monocytes and CD45+Ly6C- CD64+ macrophages.