TLR4 and acute kidney injury: Biglycan can activate the downstream MyD88 and NF-κB inflammatory signaling pathway by binding to TLR2 and TLR4, inducing the infiltration of various immune cells such as T-cells and neutrophils, polarization of M1 macrophages, and production of TNF-α, IL-1β, C-C motif chemokine ligand 2 (CCL2) and CCL5, thereby exacerbating the inflammatory injury in IRI-induced AKI (139–141).