Albumin-induced podocyte injury and protection are associated with regulation of COX-2

Kidney Int. 2014 Dec;86(6):1150-60. doi: 10.1038/ki.2014.196. Epub 2014 Jun 11.

Abstract

Albuminuria is both a hallmark and a risk factor for progressive glomerular disease, and results in increased exposure of podocytes to serum albumin with its associated factors. Here in vivo and in vitro models of serum albumin-overload were used to test the hypothesis that albumin-induced proteinuria and podocyte injury directly correlate with COX-2 induction. Albumin induced COX-2, MCP-1, CXCL1, and the stress protein HSP25 in both rat glomeruli and cultured podocytes, whereas B7-1 and HSP70i were also induced in podocytes. Podocyte exposure to albumin induced both mRNA and protein and enhanced the mRNA stability of COX-2, a key regulator of renal hemodynamics and inflammation, which renders podocytes susceptible to injury. Podocyte exposure to albumin also stimulated several kinases (p38 MAPK, MK2, JNK/SAPK, and ERK1/2), inhibitors of which (except JNK/SAPK) downregulated albumin-induced COX-2. Inhibition of AMPK, PKC, and NFκB also downregulated albumin-induced COX-2. Critically, albumin-induced COX-2 was also inhibited by glucocorticoids and thiazolidinediones, both of which directly protect podocytes against injury. Furthermore, specific albumin-associated fatty acids were identified as important contributors to COX-2 induction, podocyte injury, and proteinuria. Thus, COX-2 is associated with podocyte injury during albuminuria, as well as with the known podocyte protection imparted by glucocorticoids and thiazolidinediones. Moreover, COX-2 induction, podocyte damage, and albuminuria appear mediated largely by serum albumin-associated fatty acids.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / antagonists & inhibitors
  • Albuminuria / enzymology*
  • Animals
  • B7-1 Antigen / genetics
  • Cells, Cultured
  • Chemokine CCL2 / genetics
  • Chemokine CXCL1 / genetics
  • Cyclooxygenase 2 / drug effects
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / metabolism*
  • Enzyme Activation / drug effects
  • Fatty Acids / pharmacology
  • Gene Expression / drug effects
  • Glucocorticoids / pharmacology
  • HSP27 Heat-Shock Proteins / genetics
  • HSP70 Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / genetics
  • MAP Kinase Signaling System / drug effects
  • Mice
  • Molecular Chaperones
  • NF-kappa B / antagonists & inhibitors
  • Neoplasm Proteins / genetics
  • Podocytes / drug effects
  • Podocytes / enzymology*
  • Podocytes / pathology
  • Protein Kinase C / antagonists & inhibitors
  • RNA, Messenger / metabolism
  • Rats
  • Serum Albumin, Bovine / pharmacology*
  • Thiazolidinediones / pharmacology

Substances

  • B7-1 Antigen
  • Ccl2 protein, mouse
  • Ccl2 protein, rat
  • Chemokine CCL2
  • Chemokine CXCL1
  • Cxcl1 protein, mouse
  • Cxcl1 protein, rat
  • Fatty Acids
  • Glucocorticoids
  • HSP27 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • Heat-Shock Proteins
  • Hsbp1 protein, mouse
  • Hspb1 protein, rat
  • Molecular Chaperones
  • NF-kappa B
  • Neoplasm Proteins
  • RNA, Messenger
  • Thiazolidinediones
  • Serum Albumin, Bovine
  • Cyclooxygenase 2
  • Protein Kinase C
  • AMP-Activated Protein Kinases