title: Protective effects of L-type fatty acid-binding protein (L-FABP) in proximal tubular cells against glomerular injury in anti-GBM antibody-mediated glomerulonephritis.
abstract: BACKGROUND
  In glomerulonephritis (GN), an overload of free fatty acids (FFA) bound to albumin in urinary protein may induce oxidative stress in the proximal tubules. Human liver-type fatty acid-binding protein (hL-FABP) expressed in human proximal tubules, but not rodents, participates in intracellular FFA metabolism and exerts anti-oxidative effects on the progression of tubulointerstitial damage. We examined whether tubular enhancement of this anti-oxidative action modulates the progression of glomerular damage in immune-mediated GN in hL-FABP chromosomal gene transgenic (Tg) mice.
  
  
  METHODS
  Anti-glomerular basement membrane antibody-induced glomerulonephritis (anti-GBM GN) was induced in Tg and wild-type mice (WT). Proteinuria, histopathology, polymorphonuclear (PMN) influx, expression of tubulointerstitial markers for oxidative stress 4-hydroxy-2-Nonenal (HNE) and fibrosis (α-smooth muscle actin), proximal tubular damage (Kim-1), Peroxisome Proliferator-Activated Receptor γ (PPAR γ) and inflammatory cytokines [Monocyte Chemotactic Protein-1, tumor necrosis factor-alpha (TNF-α) and Transforming growth factor beta (TGF-β)] were analyzed. The mice were also treated with an angiotensin type II receptor blocker (ARB).
  
  
  RESULTS
  The urinary protein level in Tg mice decreased significantly during the acute phase (~Day 5). Tg mice survived for a significantly longer time than WT mice, with an attenuation of tubulointerstitial damage score and expression of each tubulointerstitial damage marker observed at Day 7. Expression of inflammatory cytokines on Day 7 was higher in WT mice than Tg mice and correlated strongly with PPARγ expression in WT mice, but not in Tg mice. Interestingly, Tg mice showed insufficient PMN influx at 3 and 6 h, with simultaneous elevation of urinary L-FABP and reduction in HNE expression. The two strains of mice showed different types of glomerular damage, with mild mesangial proliferation in Tg mice and severe endothelial swelling with vascular thrombosis in WT mice. The glomerular damage in Tg mice was improved by administration of an ARB.
  
  
  CONCLUSIONS
  The present experimental model suggests that tubular enhancement of L-FABP may protect mice with anti-GBM GN from progression of both tubulointerstitial and glomerular injury.
authors.affiliation: Department of Internal Medicine, Division of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan. yasu@juntendo.ac.jp
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kanaguchi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Ken
authors.initials: K
authors.lastname: Osaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sugaya
authors.forename: Satoshi
authors.initials: S
authors.lastname: Horikoshi
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tomino
mesh_terms: D000447:Aldehydes / Q000494:pharmacology; D057911:Angiotensin Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D001323:Autoantibodies / Q000633:toxicity*; D015153:Blotting, Western; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000652:urine; D005260:Female; D005921:Glomerulonephritis / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control*; D006801:Humans; D007249:Inflammation / Q000209:etiology / Q000517:prevention & control; D007687:Kidney Tubules, Proximal / Q000293:injuries / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D009395:Nephritis, Interstitial / Q000209:etiology / Q000517:prevention & control; D018384:Oxidative Stress; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D011507:Proteinuria / Q000209:etiology / Q000517:prevention & control; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D015996:Survival Rate; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D000447:Aldehydes; D057911:Angiotensin Receptor Antagonists; D001323:Autoantibodies; D018932:Chemokine CCL2; D015853:Cysteine Proteinase Inhibitors; D016207:Cytokines; C493319:FABP1 protein, human; D050556:Fatty Acid-Binding Proteins; D005230:Fatty Acids, Nonesterified; D047495:PPAR gamma; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; C051951:antiglomerular basement membrane antibody; C027576:4-hydroxy-2-nonenal