TWEAK Signaling Pathway Blockade Slows Cyst Growth and Disease Progression in Autosomal Dominant Polycystic Kidney Disease

Background: In autosomal dominant polycystic kidney disease (ADPKD), cyst development and enlargement lead to end-stage kidney disease. Macrophage recruitment and interstitial inflammation have been shown to promote cyst growth. TWEAK is a TNF superfamily (TNFSF) cytokine that regulates inflammatory responses, cell proliferation and cell death, and its receptor Fn14 (TNFRSF12a) is expressed in macrophage and nephron epithelia. Methods: In order to evaluate the role of the TWEAK signaling pathway in cystic disease, we evaluated Fn14 expression in human and in an orthologous murine model of ADPKD. We also explored the cystic response to TWEAK signaling pathway activation and inhibition by peritoneal injection. Results: Meta-analysis of published animal models data of cystic disease reveals mRNA upregulation of several components of the TWEAK signaling pathway. We also observed that TWEAK and Fn14 were overexpressed in mouse ADPKD kidney cysts, while TWEAK was significantly high in urine and cystic fluid from ADPKD patients. TWEAK administration induced cystogenesis and increased cystic growth, worsening the phenotype in a murine ADPKD model. Anti-TWEAK antibodies significantly slowed the progression of ADPKD, preserved renal function, and improved survival. Furthermore, the anti-TWEAK cystogenesis reduction is related to decreased cell proliferation-MAPK signaling, decreased NF-κB pathway activation, slight reduction of fibrosis and apoptosis, and an indirect decrease of macrophage recruitment. Conclusions: This study identifies the TWEAK signaling pathway as a new disease mechanism involved in cystogenesis and cystic growth and may lead to a new therapeutic approach in ADPKD.