Emodin ameliorates glucose-induced morphologic abnormalities and synthesis of transforming growth factor beta1 and fibronectin by human peritoneal mesothelial cells.
OBJECTIVE
Excessive synthesis and deposition of matrix proteins by peritoneal mesothelial cells can lead to structural and functional changes in the peritoneal membrane, jeopardizing the long-term efficacy of peritoneal dialysis (PD). Prolonged exposure to high glucose concentrations in PD fluid has been implicated as a major stimulus to matrix accumulation, through the induction of transforming growth factor beta1 (TGFbeta1). This study investigated the effect of emodin (3-methyl-1,6,8-trihydroxyanthraquinone) on TGFbeta1 and fibronectin (FN) synthesis in human peritoneal mesothelial cells (HPMCs) under high glucose concentration.


METHODS
The HPMCs were preconditioned in either 5 mmol/L or 30 mmol/L D-glucose for 2 weeks prior to the addition of emodin. Cell viability was assessed by MTT assay and lactate dehydrogenase (LDH) release. Morphology of HPMCs was studied by phase-contrast microscopy. Modulation of TGFbeta1 and FN synthesis at transcription and translation were investigated by reverse transcriptase polymerase chain reaction (RT-PCR), ELISA, and Western blot analysis.


RESULTS
When cultured under 30 mmol/L D-glucose, HPMCs demonstrated increased cell volume, multinucleation, and denudation of the monolayer, as compared with cells cultured under a physiologic (5 mmol/L) glucose concentration. High glucose concentration induced TGFbeta1 synthesis by HPMCs (217.17 +/- 14.88 pg/mL at 5 mmol/L D-glucose vs 370.33 +/- 20.67 pg/mL at 30 mmol/L D-glucose, p < 0.0001), and FN synthesis was induced at transcription and translation. Mannitol at 30 mmol/L did not affect HPMC morphology; matrix synthesis was also unaltered. Administration of emodin together with 30 mmol/L D-glucose resulted in amelioration of cell enlargement and exfoliation, and abrogation of TGFbeta1 induction (370.33 +/- 20.67 pg/mL for 30 mmol/L D-glucose alone vs 260.50 +/- 17.89 pg/mL for 30 mmol/L D-glucose + emodin, p < 0.0001). Synthesis of FN induced by high glucose was also reduced by 40% in the presence of emodin.


CONCLUSIONS
These findings provide the first evidence that emodin can ameliorate high glucose-induced matrix synthesis in HPMCs by suppression of TGFbeta1. Emodin may thus be useful in preserving peritoneal integrity in PD.
Yung
S
S
Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, PR China.
Liu
Z H
ZH
Lai
K N
KN
Li
L S
LS
Chan
T M
TM
D015153:Blotting, Western; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004642:Emodin / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D004848:Epithelium / Q000378:metabolism / Q000473:pathology; D005353:Fibronectins / Q000096:biosynthesis* / Q000235:genetics; D015870:Gene Expression; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D008353:Mannitol / Q000494:pharmacology; D010530:Peritoneal Dialysis; D010537:Peritoneum / Q000378:metabolism* / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000096:biosynthesis* / Q000235:genetics; D053773:Transforming Growth Factor beta1
D005353:Fibronectins; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D008353:Mannitol; D005947:Glucose; D004642:Emodin