title: Cell-specific delivery of a transforming growth factor-beta type I receptor kinase inhibitor to proximal tubular cells for the treatment of renal fibrosis.
abstract: OBJECTIVE
  Activation of tubular epithelial cells by transforming growth factor-beta (TGF-beta) plays an important role in the pathogenesis of renal tubulointerstitial fibrosis. We developed a renally accumulating conjugate of a TGF-beta type-I receptor kinase inhibitor (TKI) and evaluated its efficacy in vitro and in vivo.
  
  
  METHODS
  TKI was conjugated to the protein Lysozyme (LZM) via a platinum-based linker. TKI-LZM was evaluated in human tubular cells (HK-2) for its anti-fibrotic activity. Plasma, kidney and urine drug levels after a single intravenous dose of TKI-LZM in rats were determined by HPLC or immunodetection. Anti-fibrotic effects of TKI-LZM were examined in the unilateral ureteral obstruction (UUO) model.
  
  
  RESULTS
  TKI-LZM conjugate was successfully synthesized at an 1:1 drug/carrier ratio, and inhibited TGF-beta1-induced procollagen-1alpha1 gene expression in HK-2 cells. In vivo, TKI-LZM accumulated rapidly in tubular cells and provided a local depot for 3 days. Interestingly, a single dose of TKI-LZM inhibited the activation of tubular cells and fibroblasts in UUO rats and reduced renal inflammation. In contrast, free TKI at an equimolar (low) dosage exhibited little effects.
  
  
  CONCLUSIONS
  Inhibition of TGF-beta signaling by local drug delivery is a promising antifibrotic strategy, and demonstrated the important role of tubular activation in renal fibrosis.
authors.affiliation: Department of Pharmacokinetics and Drug Delivery, Groningen Research Institute for Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands. J.Prakash@rug.nl
authors.forename: Jai
authors.initials: J
authors.lastname: Prakash
authors.forename: Martin H
authors.initials: MH
authors.lastname: de Borst
authors.forename: Annemiek M
authors.initials: AM
authors.lastname: van Loenen-Weemaes
authors.forename: Marie
authors.initials: M
authors.lastname: Lacombe
authors.forename: Frank
authors.initials: F
authors.lastname: Opdam
authors.forename: Harry
authors.initials: H
authors.lastname: van Goor
authors.forename: Dirk K F
authors.initials: DK
authors.lastname: Meijer
authors.forename: Frits
authors.initials: F
authors.lastname: Moolenaar
authors.forename: Klaas
authors.initials: K
authors.lastname: Poelstra
authors.forename: Robbert J
authors.initials: RJ
authors.lastname: Kok
mesh_terms: D000818:Animals; D002460:Cell Line; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D000090602:Collagen Type I, alpha 1 Chain; D004195:Disease Models, Animal; D004337:Drug Carriers; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D005355:Fibrosis; D006801:Humans; D007275:Injections, Intravenous; D007674:Kidney Diseases / Q000188:drug therapy* / Q000201:enzymology / Q000209:etiology / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D008297:Male; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011720:Pyrazoles / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014517:Ureteral Obstruction / Q000150:complications* / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology
chemical_list: D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D004337:Drug Carriers; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; D053773:Transforming Growth Factor beta1; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625843:Tgfbr1 protein, rat; D009113:Muramidase