CX3CL1 and renal fibrosis: Whereas Engel et al. (2015) report that CX3CR1 deficiency enhances renal fibrosis, Song et al. (2013), in their study on the role of the CX3CL1/CX3CR1 system in diabetic nephropathy, show that markers of renal inflammation, fibrosis and ECM (such as the fractional mesangial area, fibronectin and collagen) were significantly lower in diabetic CX3CR1 knockout (KO) mice compared to diabetic wild-type (WT) mice.