TREM2 and Hypercholesterolemia: In response to d-flow under hypercholesterolemia, all MΦ clusters significantly accumulated, most notably MΦ3 and MΦ4 that highly expressed the markers of foam cells (Trem2, Lgals3, Gpnmb, Spp1, Lpl, and Fabp5) (Figure 4B, 4C Panels 9–10).