Role of TGF-beta1, extracellular matrix, and matrix metalloproteinase in the healing process of the pancreas after induction of acute necrotizing pancreatitis using arginine in rats.
BACKGROUND
Pancreatic tissues are almost completely restored to normal after an attack of acute pancreatitis, once the cause of the disease is removed. Transforming growth factor (TGF)-beta and extracellular matrix (ECM) are known to play an important role in the process of wound healing in pathologic diseases. Tissue repair is a process regulated by a balance between synthesis and degradation of ECM.


OBJECTIVE
To elucidate the role of TGF-beta, ECM, and matrix metalloproteinase (MMP) in the process of regeneration occurring after acute necrotizing pancreatitis.


METHODS
Acute necrotizing pancreatitis was induced by intraperitoneal injection of 500 mg/100 g body weight of L-arginine in male Wistar rats. Expression of TGF-beta1 and ECM messenger RNA (mRNA) was determined by Northern blot analysis, and that of MMP-1 and MMP-2 mRNA was examined by the reverse transcription polymerase chain reaction (RT-PCR). Immunoreactivity for ECM components, TGF-beta1, and MMP-2 in the pancreas was assessed by using a monoclonal antibody.


RESULTS
TGF-beta1 mRNA expression reached a peak value on day 2.5, with a decrease on day 3, and reached the control level on day 7. Procollagen types III and IV and fibronectin mRNA reached a peak value on day 2.5, whereas the expression level of procollagen type I mRNA was maximal on day 3, and gradually decreased to control levels by day 7. MMP-2 mRNA was significantly elevated on day 3, and peaked on day 5, whereas MMP-1 mRNA levels did not change throughout the observation period. Immunoreactivity for MMP-2 was observed around disrupted acinar cells and interstitial spaces on day 3, and maximally on day 7. Immunoreactivity for fibronectin was detected around disrupted acinar cells and interstitial spaces. On day 7, it was less than on day 5 around disrupted acinar cells and interstitial spaces, whereas in the regenerated acinar cells, it was undetected.


CONCLUSIONS
Our results show that TGF-beta1 mRNA expression peaked earlier than that of ECM mRNA. Furthermore, increased level of the MMP-2 transcript was followed by disappearance of fibronectin. Our findings suggest that TGF-beta1 plays an important role in ECM production in the early phase of acute pancreatitis, and that MMP-2 is involved in the subsequent healing process.
Kihara
Y
Y
Third Department of Internal Medicine, University of Occupational and Environmental Health, Japan, School of Medicine, Kitakyushu.
Tashiro
M
M
Nakamura
H
H
Yamaguchi
T
T
Yoshikawa
H
H
Otsuki
M
M
D000818:Animals; D001120:Arginine; D015152:Blotting, Northern; D024061:Collagen Type III / Q000235:genetics; D024141:Collagen Type IV / Q000032:analysis / Q000235:genetics; D005109:Extracellular Matrix / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000235:genetics; D005353:Fibronectins / Q000032:analysis / Q000235:genetics; D015870:Gene Expression; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000235:genetics; D020778:Matrix Metalloproteinase 2 / Q000235:genetics; D020782:Matrix Metalloproteinases / Q000502:physiology*; D010179:Pancreas / Q000503:physiopathology; D019283:Pancreatitis, Acute Necrotizing / Q000139:chemically induced / Q000503:physiopathology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000502:physiology*; D053773:Transforming Growth Factor beta1
D024061:Collagen Type III; D024141:Collagen Type IV; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D012333:RNA, Messenger; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D001120:Arginine; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020781:Matrix Metalloproteinase 1