Time-course analysis of cardiac and serum galectin-3 in viral myocarditis after an encephalomyocarditis virus inoculation

Figures

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  Fig 1. Time-course of representative microphotographs of H&E staining, Azan staining for fibrotic lesions, and immunohistochemistry for galectin-3 and Iba1 in heart tissues at 0, 12, 24, 48, 96 hours, 7 and 10 days after intraperitoneal inoculation of EMCV. For both H&E and Azan staining, notable changes was not observed until 48 hours after EMCV inoculation. Infiltration of inflammatory cells and fibrosis was observed 96 hours after inoculation. Inflammation and fibrosis peaked at 7 days after inoculation. At 0, 12 and 24 hours, there were no galectin-3 and Iba1-positive cell in heart tissues. At 48 hours after EMCV inoculation, interstitial infiltration of a few cells was detected by both galectin-3 and Iba1 immunohistochemistry, and this infiltration was greater at 96 hours. It peaked on day 7 and was observed until day 10. Scale bar = 100 μm.

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  Fig 2. Immunofluorescence images confirming the co-localization of galectin-3 and Iba1 immunoreactivity in activated macrophages/histiocytes in myocarditis lesion 96 hours after EMCV inoculation. Galectin-3 and Iba1 were expressed in the same cells of merged photograph, indicating that infiltrating galectin-3 positive cells are macrophages. Scale bar = 100 μm.

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  Fig 3. Quantification and association between the galectin-3 positive cell number and the degree of fibrosis. A, The number of galectin-3 positive cells (determined by immunohistochemistry) showing myocardial infiltration was counted at each time point. B, The degree of myocardial fibrosis (determined by of Azan staining) was quantified as percentage of fibrotic area to total myocardial tissue at each time point. C, Association between galectin-3 positive cell number and degree of fibrosis. The galectin-3 positive cell numbers were positively correlated with the degree of myocardial fibrosis. *Statistically different from each group (p < 0.05), determined by ANOVA.

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  Fig 4. A, The serum level of galectin-3. Serum level of galectin-3 increased markedly 96 hours after virus inoculation, and continued to increase until 7 days. Data suggest there is an association between serum galectin-3 level and galectin-3 positive cell numbers or fibrosis in the cardiac tissues. *Statistically different from each group (p < 0.05), determined by ANOVA. B, Association between galectin-3 positive cell number and serum levels of galectin-3. The galectin-3 positive cell numbers were positively correlated with serum levels of galectin-3. *Statistically different from each group (p < 0.05), determined by ANOVA.

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  Fig 5. Immunohistochemistory of galectin-3 in the cardiac tissue of δ-SG KO mice which is the model of dilated cardiomyopathy (DCM). The infiltration of galectin-3 positive cells were shown. Arrows indicate galection-3 postitive cells. Scale bar = 50 μm.