Loss of TLR-9 elicited no obvious effects as regards renal function or histology during AKI in the early phases (24–48 h), while TLR-9 KO attenuated renal fibrosis (as shown using fibronectin and collagen III) and epithelial-to-mesenchymal transition (EMT) [E-cadherin (E-Cad) and α-smooth muscle actin (α-SMA)] on the long-term after AKI through the inhibition of macrophages infiltration, especially M2 macrophages. The gene discussed is FN1; the disease is renal fibrosis.