High glucose decreases collagenase expression and increases TIMP expression in cultured human peritoneal mesothelial cells.
BACKGROUND
Peritoneal fibrosis (PF), a serious problem in long-term continuous ambulatory peritoneal dialysis (CAPD) patients, is characterized by extracellular matrix (ECM) accumulation which results from an imbalance between the synthesis and the degradation of ECM components. Previous studies have demonstrated that ECM synthesis is increased in human peritoneal mesothelial cells (HPMCs) under high glucose conditions, but the effects of high glucose on degradative pathways have not been fully explored. This study was undertaken to elucidate the effects of high glucose on these proteolytic processes in cultured HMPCs.


METHODS
HPMCs were isolated from human omentum and were exposed to 5.6 mM glucose (NG), 5.6 mM glucose +34.4 mM mannitol (NG + M), or 40 mM glucose (HG) with or without PKC inhibitor (PKCi). Real-time PCR and western blot were performed to determine collagenases (MMP-1, -8 and -13) and TIMPs (TIMP-1 and -2) mRNA and protein expression, respectively. The individual activities of collagenases in culture media were determined by ELISA.


RESULTS
Types I and III collagen protein expression were significantly increased in HG-conditioned media compared to NG media (P < 0.05). The MMP-1, -8 and -13/GAPDH mRNA ratios were significantly lower in HPMCs exposed to HG medium compared to NG cells by 64, 52 and 37%, respectively, and their protein expression by 76, 42 and 49%, respectively, in HG- vs NG-conditioned media. The activities of collagenases in HG-conditioned media were also significantly lower than those in NG media (P < 0.05). In contrast, HG significantly increased TIMPs mRNA ratios and protein expression in HPMCs. These changes in collagenase and TIMP expression induced by HG were abrogated upon pre-treatment with PKCi.


CONCLUSIONS
In conclusion, impaired matrix degradation may contribute to ECM accumulation in PF.
Kim
Jin-Ju
JJ
Yonsei University College of Medicine, Department of Internal Medicine, 134 Shinchon-Dong Seodaemoon-Gu, Seoul, Korea, 120-752.
Li
Jin-Ji
JJ
Kim
Kyung Sik
KS
Kwak
Seung-Jae
SJ
Jung
Dong-Sub
DS
Ryu
Dong-Ryeol
DR
Yoo
Tae-Hyun
TH
Choi
Hoon Young
HY
Han
Seung Hyeok
SH
Kim
Hyung Jong
HJ
Yoon
Soo Young
SY
Han
Dae Suk
DS
Kang
Shin-Wook
SW
D002478:Cells, Cultured; D017364:Collagenases / Q000096:biosynthesis* / Q000235:genetics; D004847:Epithelial Cells / Q000378:metabolism*; D024022:Fibrillar Collagens / Q000378:metabolism; D005355:Fibrosis; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D010537:Peritoneum / Q000166:cytology* / Q000473:pathology*; D012333:RNA, Messenger / Q000096:biosynthesis; D019714:Tissue Inhibitor of Metalloproteinases / Q000096:biosynthesis*
D024022:Fibrillar Collagens; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D017364:Collagenases; D005947:Glucose