Pharmacological inhibition of fatty acid-binding protein 4 alleviated kidney inflammation and fibrosis in hyperuricemic nephropathy

Hyperuricemia is an independent risk factor for chronic kidney disease (CKD). Excessive uric acid (UA) level in the blood leads to hyperuricemic nephropathy (HN), which is characterized by glomerular hypertension, arteriolosclerosis and tubulointerstitial fibrosis. Fatty acid binding protein 4 (FABP4) is a potential mediator of inflammatory responses which contributes to renal interstitial fibrosis. However, the roles of FABP4 in HN remains unknown. In the study, a mouse model of HN induced by feeding a mixture of adenine and potassium oxonate, severe kidney injury and interstitial fibrosis, as well as the increased kidney-expressed FABP4 protein level were evident, accompanied by the activation of inflammatory responses. Oral administration of BMS309403, a highly selective FABP4 inhibitor, improved renal dysfunction, inhibited the mRNA level of KIM-1 and NGAL, as well as reduced the expression of proinflammatory cytokines and fibrotic proteins in the injured kidneys. BMS309403 treatment also inhibited the FABP4 activity and further suppressed the activation of JAK2-STAT3 and NF-kB P65 signaling pathways in the hyperuricemia-injured kidneys and UA-stimulated human tubular epithelial (HK-2) cells, respectively. In summary, our study for the first time demonstrated that FABP4 played a crucial role in kidney inflammation and fibrosis via the regulation of JAK2-STAT3 and NF-kB P65 pathways in HN mice. The results suggested that FABP4 inhibition might be a promising therapeutic strategy for HN.