Matrix metalloproteinase-II (MMP-II, 72-kd type IV collagenase, or gelatinase) is one of the gene families of zinc enzymes capable of degrading extracellular matrix molecules, and specifically of degrading type IV and V collagens, gelatin, fibronectin, and elastin. In this study, we used both the liver fibrosis model and the reversibility model of experimental cirrhosis to clarify how MMP-II participates in liver fibrosis of rats. To produce fibrosis model, rats received subcutaneous injections of CCl4 twice weekly for 7, 9, or 14 weeks. For the reversibility model, rats were treated with CCl4 three times a week for 8 weeks and killed at 3, 7, 14, 28, or 42 days after discontinuation of treatment. MMP-II gene expression was studied by Northern hybridization technique, and gelatinase activity of MMP-II was examined by zymography using gelatin substrate. At the same time, an immunohistochemical study using anti-type IV collagen antibody was carried out. In liver fibrosis model, nodule formation was established at 14 weeks. Immunodeposit of type IV collagen was increased in wide fibrous septa and was clearly observed along sinusoidal wall. Gene expression of MMP-II increased up to 7 to 12 times compared with that of controls, with the expression rate being maximum at an intermediate stage of fibrosis. Zymography showed the expressions of both 65-kd latent MMP-II, which is confirmed to be activated by adding p-aminophenylmercuric acetate, and 62-kd active MMP-II during fibrosis. The expression of both forms increased 13 to 28 times as the fibrosis progressed.(ABSTRACT TRUNCATED AT 250 WORDS)

ABSTRACT— Monospecific antibodies, directed against type IV collagen and laminin, were used to clarify the process of sinusoidal capillarization in rats after carbon tetrachloride (CCl4) intoxication by the direct immunoperoxidase method. After acute intoxication, both type IV collagen and laminin were increased in the area of hepatic necrosis, adjacent to the central veins; however, sinusoidal capillarization was not found. During chronic intoxication, deposition of laminin was co‐distributed with that of type IV collagen, but deposition proceeded more slowly than that of the type IV collagen. Deposition of laminin was increased in the Disse space. Sinusoidal capillarization was noted as thick deposition of both antigens by light microscopy. Immunoelectron microscopy showed that both components were continuously present in the Disse space. Intracellularly, both antigens were found in the rough endoplasmic reticulum (RER) of fat‐storing cells (FSC) and endothelial cells, and these cells showed morphological changes, becoming slender and flattened. In contrast, few immunoreactive products of the two components were observed in the hepatocytes. These findings suggest that type IV collagen and laminin are indispensable for the establishment of sinusoidal capillarization, and that FSC play an important role in the production of both components.

Inflammatory fibroid polyp (IFP) is a rare benign tumor originating from the submucosa of the gastrointestinal tract. Most are found in the stomach, with only one previous case reported in the rectum. IFPs are typically larger than 1 cm in diameter and present symptoms. Colonoscopic examination of an asymptomatic 66-year-old man revealed a small submucosal tumor, 3 mm in diameter, in the rectum. The lesion was completely resected by endoscopic submucosal dissection (ESD) and was histopathologically diagnosed as IFP. We report herein a very rare rectal IFP that could be treated and diagnosed with ESD.

ABSTRACT— Immunolocalization of Type I, Type III and Type IV collagens, laminin and prolyl hydroxylase (PH), a key enzyme in collagen synthesis, was examined to clarify the fibrotic process in chronic, active liver disease. In piecemeal necrosis of chronic, active hepatitis (CAH) and active liver cirrhosis (LC), fat‐storing cells (FSCs) and transitional cells (TSCs), containing abundant rough endoplasmic reticulum (RER), were increased in number and stained intensely for PH. Immunodeposits of extracellular matrix (ECM) components were found in the RER, Golgi apparatus (GA) and vesicles of these cells, especially in cases with marked inflammation. On the other hand, in the periportal areas of chronic, persistent hepatitis (CPH) or inactive LC, immunoreaction of ECM components was seldom found in the RER of FSCs and TSCs. In the portal tract, immunodeposits of ECM components were seldom found in the organelles of fibroblasts, although ECM was increased there. These findings indicate that FSCs and TSCs in piecemeal necrosis might play a role in the production of ECM components in the progression of fibrosis during the development of chronic active liver disease. In addition, ECM component production by FSCs and TSCs is associated with marked inflammation.

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