Fig. 4.

Comparison of immature and mature scars in Dsg2^MT mice identify macrophages as the predominant immune cell population in both and shows that increased expression of inflammation-associated cytokines is strongly reduced in mature scars. a The micrographs show tissue cryosections that were obtained from 4 and 12 week-old Dsg2^MT mice (immature scars [n = 3] and mature scars [n = 4], respectively) and corresponding wild-type Dsg2^WT mice (WT; n = 3–5) after reaction with antibodies directed against various immune cell-specific surface antigens. All images are shown at the same magnification (scale bar in the picture at the upper left corner). Note that CD11b⁺ and F4/80⁺ macrophages are the predominant immune cell type in immature and mature scars and that the number of CD3⁺ T cells is higher in immature than in mature scars. Typical round-shaped CD4⁺ T cells are present in immature scars, whereas primarily spindle-shaped CD4⁺ cells are detected in mature scars. CD8a⁺ cells were only rarely detected in Dsg2^MT and control hearts (arrowheads). b Tukey's whisker plots show the results of qRT-PCR analyses assessing the mRNA expression (normalized relative quantification; NRQ) of inflammation-associated cytokines in total hearts of Dsg2^MT (n = 5–7) and Dsg2^WT mice (n = 5–7) at 4 and 12 weeks. They are significantly upregulated in Dsg2^MT mice of both age groups compared to the wild-type controls (broken lines). However, their expression decreases with age. The non-parametric Mann Whitney test was applied to compare Dsg2^WT and Dsg2^MT expression within each age group. *p < 0.05 and **p < 0.01. More detailed statistic data are provided in Supplementary Table 5