Cell isolation

Peripheral blood was collected by retro-orbital bleeding, and erythrocytes were lysed in RBC lysis buffer (BioLegend). Spleen, draining LNs, femurs, tibia, and heart were excised after vascular perfusion with cold PBS. Minced spleen and LNs and flushed BM were strained through 40-µm nylon mesh (BD Biosciences) and further subjected to RBC lysis. The naive and inflamed hearts were minced and digested with 450 U/ml collagenase I, 125 U/ml collagenase XI, 60 U/ml DNase I, and 60 U/ml hyaluronidase (Sigma-Aldrich) in PBS for 1 h at 37°C while shaking. For cell sorting, single-cell suspensions of heart tissue from indicated animals were made as described above and stained to identify indicated cell populations. Cells were sorted on a FACS Aria II cell sorter (BD Biosciences) directly into either RLT lysis buffer (Qiagen) for subsequent RNA isolation or complete medium for cell culture experiments.