title: The osteoprotegerin/tumor necrosis factor related apoptosis-inducing ligand axis in the kidney.
abstract: OBJECTIVE
  Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a cytokine belonging to the TNF superfamily. TRAIL may modulate cell survival and proliferation through interaction with two different receptors, TRAIL-R1 and TRAIL-R2. The actions of TRAIL are regulated by three decoy receptors, TRAIL-R3, TRAIL-R4 and osteoprotegerin (OPG). There is evidence that both TRAIL and OPG are expressed by renal cells. The OPG/TRAIL axis has been recently linked to the pathogenesis of renal damage and, in particular, diabetic nephropathy.
  
  
  RESULTS
  In patients with kidney diseases, serum TRAIL and OPG levels are increased in parallel and are significantly associated with each other. In diabetic nephropathy, the renal expression of TRAIL and OPG is elevated, and in tubular cells proinflammatory cytokines enhance TRAIL expression. Additionally, a high-glucose microenvironment sensitizes tubular cells to apoptosis induced by TRAIL, whereas OPG counteracts the actions of TRAIL in cultured cells.
  
  
  CONCLUSIONS
  It seems that the expression and levels of TRAIL and OPG at serum and kidney levels are crucial for the pathogenesis of kidney diseases, and in particular diabetic nephropathy. Although further studies are necessary to clarify the exact role of the OPG/TRAIL axis in the kidney, this system seems to hold promise to provide therapeutic approaches for the management of renal damage.
  
  
  BACKGROUND
  See the Video Supplementary Digital Content 1 (http://links.lww.com/CONH/A5).
authors.affiliation: Diabetes Centre, A.S.S. 1 Triestina, Trieste, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Candido
mesh_terms: D000818:Animals; D017209:Apoptosis; D003928:Diabetic Nephropathies / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D053244:Osteoprotegerin / Q000378:metabolism*; D051436:Renal Insufficiency, Chronic / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*
chemical_list: D053244:Osteoprotegerin; D053221:TNF-Related Apoptosis-Inducing Ligand