Heterogeneity of liver cells expressing procollagen types I and IV in vivo

Abstract

The extracellular matrix of fibrotic liver is predominantly produced by mesenchymal cells, the in vivo phenotype of which is poorly defined. We report on the application of combined immunohistology and in situ hybridization with [35S]-labeled alpha 1(I) and alpha 1(IV) procollagen RNA probes. In CCl4-treated rats, all alpha 1(I) procollagen-producing cells were vimentin positive but cytokeratin negative; over 90% expressed desmin, a marker of rat liver stellate cells. alpha 1(I) Procollagen-expressing, desmin-negative cells were confined to portal tract and perivascular stroma. Similarly, alpha 1(I) procollagen gene transcripts were, in all instances, colocalized with vimentin in human liver. In fibrotic specimens, over 70% of these cells expressed alpha-actin. Antibodies against epithelial, endothelial, and Kupffer cells, granulocytes, and lymphocytes did not react with alpha 1(I) procollagen RNA-expressing cells. Localization, morphology, and immunophenotype of alpha 1(I) procollagen-expressing cells indicated stellate cells and portal/vascular fibroblasts, but not epithelial cells, to be sources of hepatic interstitial collagen. However, most alpha 1(IV)-expressing human liver cells were identified as endothelial cells, the remaining cells were (myo-)fibroblastic and bile duct epithelial cells, but not hepatocytes. This indicates synthesis of procollagen type IV from both sides of the basement membrane and suggests an active participation of endothelial cells in the process of sinusoidal capillarization.

The ecto-nucleoside triphosphate diphosphohydrolase NTPDase2/CD39L1 is expressed in a novel functional compartment within the liver

“…14,24 Molecular expression of NTPDase2 was determined using RT-PCR with NTPDase2-specific oligonucleotide primers (Fig. 6A).…”

Global analysis of host tissue gene expression in the invasive front of colorectal liver metastases

“…As expected, several positive genes in the upregulated group were ECM genes, namely, procollagen I, whose upregulation in the invasion front was confirmed by qPCR and immunohistochemistry, procollagens III, IV, V and VI, fibrillin 1, fibulin 2, lumican, SPARC and laminin B1. All these gene products are secreted by HSCs during the development of hepatic fibrosis [34][35][36][37][38][39] or in activated cultured myofibroblasts. 40,41 The ECM gene tenascin has been reported to be deposited close to HSCs within colorectal liver metastases 42 and to be associated with poor prognosis in intrahepatic cholangiocarcinoma.…”

Focal overexpression of insulin-like growth factor 2 by hepatocytes and cholangiocytes in viral liver cirrhosis

“…Informed consent was obtained prior to surgery. Preparation of slides and frozen sections (5 mm) was done as described (Herbst et al, 1997). Formalin-fixed, paraffin-embedded mature placenta served as control for immunohistology on paraffin sections.…”

“…Authenticity of the probe was verified by restriction endonuclease digestion and partial sequence analysis. Run-off transcription and 35 S-labelling of RNA probes with [ 35 S] UTP and [ 35 S] CTP were performed as described previously (Herbst et al, 1997).…”

“…In situ hybridisation in combination with immunohistology was carried out as described (Herbst et al, 1997) with monoclonal antibodies specific for cytokeratins, vimentin, desmin, and smooth muscle a-actin (clones MNF116, V9, D33, and 1A4, respectively). The antibodies were visualised by the APAAP method (Cordell et al, 1984) with affinity-purified mouse polyclonal antibodies to rabbit IgG, rabbit antibodies to mouse IgG, APAAP complex at a dilution of 1 : 40, and new fuchsin as the alkaline phosphatase substrate.…”