Relation between ultrastructural localization, changes in caveolin-1, and capillarization of liver sinusoidal endothelial cells in human hepatitis C-related cirrhotic liver - PubMed (original) (raw)
Relation between ultrastructural localization, changes in caveolin-1, and capillarization of liver sinusoidal endothelial cells in human hepatitis C-related cirrhotic liver
Hitoshi Yamazaki et al. J Histochem Cytochem. 2013 Feb.
Abstract
Most vascular endothelial cells are continuously exposed to shear stress in vivo. Caveolae are omega-shaped membrane invaginations in endothelial cells (ECs) and are enriched in cholesterol, caveolins, and signaling molecules. This study was designed to elucidate the ultrastructural localization and change in caveolin-1 expression within human liver sinusoidal endothelial cells (LSECs) during the progression of cirrhosis caused by hepatitis C, using tissue sections prepared via perfusion-fixation. Normal control liver specimens and hepatitis C-related Child-Pugh A and C cirrhotic liver specimens were studied. Caveolin-1 in the liver sinusoids was examined via immunohistochemistry, Western blotting, and immunoelectron microscopy. In control liver tissue, caveolin-1 was localized on caveolae mainly in arterial and portal endothelial cells of the portal tract and was also found on vesicles and some fenestrae in LSECs around the central vein. In cirrhotic liver tissue, aberrant caveolin-1 expression was observed on caveolae-like structures in LSECs. Caveolin-1 was especially overexpressed in late-stage cirrhosis. This study demonstrates that caveolin-1 is strongly expressed within caveolae-like structures and associated vesicles within LSECs of the hepatitis C-related cirrhotic liver. These findings suggest a direct association of caveolin-1 in the process of differentiation of LSECs in cirrhosis-mediated capillarization.
Conflict of interest statement
Declaration of Conflicting Interests: The authors declared a potential conflict of interest (e.g. a financial relationship with the commercial organizations or products discussed in this article) as follows: Hiroaki Yokomori received research grants from MSD, Chugai pharmaceutical Co. Ltd, Daiichi Sankyo Co. Ltd., Dainippon Sumitomo Pharma Co., Ltd., Zeria Pharmaceutical Co. Ltd., Otsuka Pharmaceutical Co. Ltd, and lecture fees from Otsuka Pharmaceutical Co. Ltd.
Figures
Figure 1.
Immunohistochemical distribution of caveolin-1 in control liver (a–c), Child-Pugh A cirrhotic liver (d–f), and Child-Pugh C cirrhotic liver (g–i). P, portal tract; C, central vein; Ao, hepatic artery. White arrowheads denote hepatic artery or central vein or portal vein. Black arrowheads denote hepatic sinusoid. (a–c) Control liver tissue. Immunohistochemistry revealed caveolin-1 in the hepatic artery, capillary venule, and portal vein in the portal tract (P) and is detected in the hepatic sinusoidal lining cells around pericentral zone 3. (a) Low magnification. (b) High magnification of periportal region. (c) High magnification of pericentral region. (d–f): Child-Pugh A liver tissue. In early stage cirrhotic liver, caveolin-1 expression is evident mainly at sites of proliferated capillary arteries and sinusoidal lining cells in the peripheral regions of nodules. (d) Low magnification. (e) High magnification of regenerated fibrotic region. (f) High magnification of hepatic sinusoid. (g–i) Child-Pugh C liver tissue. In late-stage cirrhotic liver, the intensity of caveolin-1 immunoreactivity is enhanced mainly on sinusoidal lining cells in the regenerated nodules and in peripheral regions of nodules and fibrous septa. Caveolin-1 immunoreactivity is more intense in severely fibrotic tissue. (g) Low magnification. (h) High magnification of regenerated fibrotic region. (i) High magnification of hepatic sinusoid. Bar = 153 µm for a, d, and g. Bar = 32 µm for b, c, e, f, h, and i.
Figure 2.
Western blot analysis of caveolin-1 protein in human control and cirrhotic liver tissues. Samples containing 30 µg protein were subjected to SDS-PAGE and analyzed by Western blotting. Lanes a and b show Child-Pugh A cirrhotic liver samples. Lanes c and d show control liver samples. Lanes e and f show Child-Pugh C cirrhotic liver samples. Caveolin-1 protein expression is significantly more intense in Child-Pugh A and C cirrhotic liver compared with control.
Figure 3.
Transmission electron micrographs showing capillary endothelial cells in normal control liver tissue. Immunogold particles indicating caveolin-1 are observed in caveolae and partly some vesicles in capillary endothelial cell. Inset shows lower magnification. EC, capillary endothelial cell. Magnification: ×20,000 (bar: 200 nm). Inset magnification: ×2000 (bar: 1 µm). White arrowheads denote caveolae.
Figure 4.
Transmission electron micrographs showing portal venue in normal control liver tissue. Immunogold particles indicating caveolin-1 are found in caveolae in endothelial cells of the portal venule. EC, endothelial cell of the portal venule; H, hepatocyte; VSMC, vascular smooth muscle cell. Magnification: ×20,000 (bar: 200 nm). Inset shows lower magnification: ×2000 (bar: 1 µm). White arrowheads denote caveolae.
Figure 5.
Transmission electron micrographs showing liver sinusoidal endothelial cells around the portal tract in normal control liver tissue. Underneath the thin layer of fenestrated endothelium, the space of Disse shows the presence of microvilli and thin fibers of reticulin. Sinusoidal endothelial fenestrae have an average diameter of about 125 nm. Immunogold particles indicating caveolin-1 are found sparsely in liver sinusoidal endothelial cells. LSEC, liver sinusoidal endothelial cell; SEF, sinusoidal endothelial fenestrae; H, hepatocyte; S, hepatic sinusoid. Magnification: ×20,000 (bar: 200 nm). Inset shows lower magnification: ×2000 (bar: 1 µm).
Figure 6.
Transmission electron micrographs showing liver sinusoidal endothelial cells around the central vein in normal control liver tissue. Immunogold particles indicating caveolin-1 are found in vesicles and sparsely in fenestrae of liver sinusoidal endothelial cells. LSEC, liver sinusoidal endothelial cell; HSC, hepatic stellate cell; SEF, sinusoidal endothelial fenestrae; H, hepatocyte. Magnification: ×20,000 (bar: 200 nm). Inset shows lower magnification: ×2000 (bar: 1 µm). White arrowheads denote vesicles.
Figure 7.
Transmission electron micrographs showing capillary, vascular, and liver sinusoidal endothelial cells in cirrhotic liver tissue. In cirrhotic liver, capillarized sinusoidal endothelial cells are different from normal sinusoidal endothelial cells; their vacuolar apparatus (pinocytotic vesicles, endosomes, lysosomes, Golgi apparatus) is not developed. Immunogold particles indicating caveolin-1 are found in caveola-like structures in capillarized liver sinusoidal endothelial cells. LSEC, liver sinusoidal endothelial cell; HSC, hepatic stellate cell; H, hepatocyte; S, hepatic sinusoid. Magnification: ×20,000 (bar: 200 nm). Inset shows lower magnification: ×2000 (bar: 1 µm). White arrowhead denotes caveolae-like structure.
Figure 8.
Transmission electron micrographs showing capillary, vascular, and liver sinusoidal endothelial cells in cirrhotic liver tissue. In cirrhotic liver, the thin endothelial lining is closed by a diaphragm. A continuous basal lamina can be seen underneath the endothelium. Immunogold particles indicating caveolin-1 are found on vesicles and caveolae in capillarized liver sinusoidal endothelial cells. LSEC, liver sinusoidal endothelial cell; HSC, hepatic stellate cell; H, hepatocyte. Magnification: ×20,000 (bar: 200 nm). Inset shows lower magnification: ×2000 (bar: 1 µm). White arrowhead denotes caveolae-like structure.
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