IntroductionTight Junction Protein–2 (TJP-2) belongs to a family of proteins that are predominantly expressed at the junctions between epithelial cells. TJP-2 has been implicated in the progression of breast and pancreatic cancer through regulation of downstream signalling pathways responsible for invasion and metastasis. Recently, gene alterations in TJP-2 have been discovered in patients with progressive familial intrahepatic cholestasis leading us to hypothesise that TJP-2 might be differentially regulated in chronic liver disease and liver cancer. Our aim was to characterise the expression of TJP-2 in liver disease with a particular focus on malignancy.MethodsThe cellular localization and expression of TJP-2 in human liver tissue sections was studied using immunohistochemistry, multi-colour confocal immunofluorescence and immunocytochemistry. TJP-2 mRNA expression was quantified by qRT-PCR and protein expression was determined by western blotting of tissue lysates prepared from pathological control and diseased liver samples. Image J analysis was used to quantify expression of TJP-2 in chronic liver disease and liver cancers.ResultsTJP-2 expression in human tissue sections was significantly downregulated in chronic liver disease and liver cancer, specifically hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), when compared to pathological control tissue. The majority of TJP-2 protein was restricted to cellular junctions of biliary epithelial cells and hepatocytes in both pathological control and chronically diseased livers. In HCC and CCA tissue sections the protein was also found to adopt a characteristic perinuclear distribution, consistent with previous studies on pancreatic cancer cell lines. Western blotting and qRT-PCR studies revealed a significant decrease in TJP-2 expression in both chronic liver disease and primary liver cancer when compared to pathological control livers. Preliminary analysis of tissue samples taken from patients who had undergone hemihepatectomy for intrahepatic cholangiocarcinoma, and who were matched for anatomical location and tumour histology, suggested a correlation between TJP-2 expression and overall survival.ConclusionThis is the first report on TJP-2 expression in liver disease. TJP-2 was expressed on epithelial cells, with reduced mRNA and protein levels detected in chronic liver disease and liver cancer, suggesting that progressive loss of this molecule may contribute to altered epithelial function in hepatic injury and malignancy. Our data suggest that measurement of TJP-2 expression might have utility in the staging of liver cancer.Disclosure of InterestNone Declared

IntroductionInflammation of the liver drives the onset and progression of chronic liver diseases whilst fostering an environment where the formation of neoplastic tumours such as hepatocellular carcinomas (HCC) can occur. A key step in this process is leukocyte recruitment via hepatic sinusoidal endothelial cells. CD151, a member of the tetraspanin family, has been shown to regulate heterotypic partner proteins involved in leukocyte recruitment and therefore an understanding of the expression and function of CD151 in the liver could identify new organ-specific anti-inflammatory therapies.MethodsWe used immunohistochemistry, dual colour immunofluorescence co-localisation studies, qRT-PCR and western blotting to determine the cell specific expression of CD151 in pathological control liver, chronic liver diseases and tissue taken from patients with HCC. Cell-based ELISA, qRT-PCR and western blotting were then used to determine the regulation of CD151 expression by hepatic sinusoidal endothelial cells (HSEC) following growth factor and cytokine treatment to mimic inflammatory and tumourigenic environments. Flow-based adhesion assays were used to study the role of CD151 in the adhesion of Jurkat cells, a human T cell line, to HSEC monolayers with subsequent immunofluorescence analysis.ResultsIncreased CD151 protein expression was associated with areas of fibrosis and neovascularisation, particularly in parenchymal liver disease such as alcoholic and non-alcoholic fatty liver disease as well as in HCC. CD151 was highly expressed by HSEC both within liver tissue and in vitro. The expression of CD151 in HSEC was upregulated by stimulation with tumour cell line supernatant or a combination of hepatocyte and vascular endothelial growth factors. We found CD151 molecules clustering around adherent Jurkat cells following capture from flow by HSEC monolayers. Function-blocking antibodies to CD151 significantly reduced adherence of Jurkat under conditions of shear stress.ConclusionWe demonstrate for the first time the expression of CD151 on human sinusoidal endothelial cells and that this molecule is expressed in neovessels in chronic liver disease and HCC. We also demonstrate that CD151 is upregulated by pro-tumourigenic factors on HSEC and functionally plays a role in T cell adhesion to HSEC. These findings further our understanding of liver inflammation and lymphocyte recruitment to the organ, in both chronic and malignant disease, and could form the basis of a potential therapeutic target.Disclosure of InterestNone Declared