title: Renal-targeting triptolide-glucosamine conjugate exhibits lower toxicity and superior efficacy in attenuation of ischemia/reperfusion renal injury in rats.
abstract: OBJECTIVE
  We previously reported a novel triptolide (TP)-glucosamine conjugate (TPG) that specifically accumulated in kidneys and protected renal function from acute ischemia/reperfusion (I/R) injury in rats. In this study we further examined the molecular mechanisms underlying the renoprotective action of TPG.
  
  
  METHODS
  The renal-targeting of TPG was investigated in a human proximal renal tubular epithelial cell line (HK-2) by measuring cell uptake of TP or TPG. The effects of TP or TPG on cell cycle distribution and apoptosis rate of HK-2 cells were assessed, and the activities of caspase-3 and caspase-9 were also measured. SD rats were subjected to bilateral renal ischemia by temporarily clamping both renal pedicles. The rats were administered TP (4.17 μmol·kg-1·d-1, iv) or TPG (4.17 μmol·kg-1·d-1, iv) for 3 d before the renal surgery. The kidneys were harvested after 24 h of recovery from the surgery. The levels of oxidative stress, proinflammatory cytokines, chemotactic cytokines and intracellular adhesion molecules in kidneys were examined.
  
  
  RESULTS
  The uptake of TPG in HK-2 cells was 2-3 times higher than that of TP at the concentrations tested. Furthermore, TPG targeting the proximal tubules was mediated through interactions with megalin receptors. TP (40-160 nmol/L) concentration-dependently increased G2/M arrest, apoptosis and caspase-3/caspase-9 activity in HK-2 cells, whereas the same concentrations of TPG did not show those features when compared with the control group. In I/R-treated rats, TPG administration caused more robust down-regulation of proinflammatory cytokines (TNF-α, IL-6, IL-1, TGF-β) and chemotactic cytokines (MCP-1) in the kidneys compared with TP administration, suggesting the inhibition of the proliferation and accumulation of lymphocytes. And TPG administration also caused more prominent inhibition on the levels of oxidative stress and intracellular adhesion molecules in the kidneys, compared with TP administration.
  
  
  CONCLUSIONS
  The renal-targeting TPG is more effective and less toxic than TP, in amelioration of I/R-induced rat renal injury, which may provide a new avenue for the treatment of acute kidney injury.
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Lin
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Gong
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
authors.forename: Xun
authors.initials: X
authors.lastname: Sun
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
authors.forename: Zhi-Rong
authors.initials: ZR
authors.lastname: Zhang
mesh_terms: D058186:Acute Kidney Injury / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D002465:Cell Movement; D004224:Diterpenes / Q000627:therapeutic use* / Q000633:toxicity; D005944:Glucosamine / Q000627:therapeutic use* / Q000633:toxicity; D006801:Humans; D007511:Ischemia / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D007668:Kidney / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D007684:Kidney Tubules / Q000378:metabolism / Q000473:pathology; D007962:Leukocytes / Q000502:physiology; D015227:Lipid Peroxidation; D008297:Male; D058990:Molecular Targeted Therapy; D009336:Necrosis; D018384:Oxidative Stress; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology
chemical_list: D015815:Cell Adhesion Molecules; D004224:Diterpenes; D005944:Glucosamine; C110936:Havcr1 protein, rat