CD68 and acute kidney injury: Compared to the bilirubin or nPLBR group, the proportion of CD68+ macrophages and TNF‐α in the kidneys of AKI‐damaged rats treated with hyaluronic acid (HA) coated ε‐polylysine‐bilirubin conjugate (PLBR) nanoparticle (nHA/PLBR) was significantly decreased (Figure 4B,C).[124] This indicates that bilirubin has a significant protective role in AKI by reducing monocyte infiltration.