Figure 5. Phenotypic analysis of myocardial-infiltrating macrophages in miR-155^−/− and WT mice during CVB3-induced VM.

miR-155^−/− and WT mice received 1 × 10⁵ PFU of CVB3 i.p. on day 0, and hearts were collected on day 7 post-infection. Myocardial infiltrating leukocytes were isolated from the hearts after enzymatic digestion. (A) The percentage and absolute numbers of F4/80⁺ cells were analyzed by FACS. (B) Infiltrating CD45⁺ leukocytes are subsetted by bivariate analysis of F4/80 and CD11b expression, revealing distinct populations: UL, F4/80⁻CD11b^high monocytes; UR, F4/80⁺CD11b^high macrophages; CD206 and CD301 expression were then determined by FACS, based on gates set from F4/80⁺ macrophages. (C) Arginase activity of sorted F4/80⁺ macrophages was assessed by an assay of urea production from arginine substrate and was normalized to cell counts. (D) NOS2, Arg1, FIZZ1, and YM-1 of sorted F4/80⁺ macrophages were determined by real-time PCR. Experiments were repeated three times in triplicate with 10 mice per group. Bar graph data are presented as mean ± SD; **P < 0.01 and ***P < 0.001 as compared with WT.