Alaa Melhem

Human hepatic stem cells from fetal and postnatal donors

Human hepatic stem cells (hHpSCs), which are pluripotent precursors of hepatoblasts and thence of hepatocytic and biliary epithelia, are located in ductal plates in fetal livers and in Canals of Hering in adult livers. They can be isolated by immunoselection for epithelial cell adhesion molecule–positive (EpCAM+) cells, and they constitute ∼0.5–2.5% of liver parenchyma of all donor ages. The self-renewal capacity of hHpSCs is indicated by phenotypic stability after expansion for >150 population doublings in a serum-free, defined medium and with a doubling time of ∼36 h. Survival and proliferation of hHpSCs require paracrine signaling by hepatic stellate cells and/or angioblasts that coisolate with them. The hHpSCs are ∼9 μm in diameter, express cytokeratins 8, 18, and 19, CD133/1, telomerase, CD44H, claudin 3, and albumin (weakly). They are negative for α-fetoprotein (AFP), intercellular adhesion molecule (ICAM) 1, and for markers of adult liver cells (cytochrome P450s), hemopoietic cells (CD45), and mesenchymal cells (vascular endothelial growth factor receptor and desmin). If transferred to STO feeders, hHpSCs give rise to hepatoblasts, which are recognizable by cordlike colony morphology and up-regulation of AFP, P4503A7, and ICAM1. Transplantation of freshly isolated EpCAM+ cells or of hHpSCs expanded in culture into NOD/SCID mice results in mature liver tissue expressing human-specific proteins. The hHpSCs are candidates for liver cell therapies.

Treatment of chronic hepatitis B virus infection via oral immune regulation toward hepatitis B virus proteins.

OBJECTIVES:Hepatitis B virus (HBV) is a noncytopathic virus, and hepatocellular injury is mediated by a defective host antiviral immune response. We have previously shown that antiviral immunity can be modulated through oral feeding of viral proteins. The aims of this study were to determine the safety and efficacy of treatment of patients with chronic HBV by means of p.o. administration of HBV envelope proteins.METHODS:A total of 42 chronic HBV patients were treated p.o. with HBV envelope proteins (HBsAg+preS1+preS2), three times/wk for 20–30 wk, and followed for an additional 20 wk. Patients were monitored for HBV-DNA levels, liver enzymes, and liver histology. HBV-directed T cell immune modulation was assessed in vitro by HBV specific T cell-proliferation, cytotoxicity, IFNγ, and IL10 ELISPOT assays, and reverse transcription–polymerase chain reaction cytokines assay.RESULTS:Favorable response in one of the primary endpoints was achieved in 28/42 patients (66.6%) by means of p.o. immune regulation. A significant decrease in viral load was observed in 15 patients (35.7%). HBsAg/HBcAg biopsy scores improved in 41% and 57.1% of patients, respectively. Histological improvement in liver necroinflammatory score was noted in 12/40 patients (30%). In all, 80% showed biochemical response. Five of 19 HBeAg positive patients (26.3%) became negative for HBeAg. A favorable augmentation in anti-HBV specific T cell response, with increased HbsAg specific T cell proliferation (78%), cytotoxicity (75%), and IFNγ positive T cell clones (62.9%) was noted. In addition, a decrease in the IL10 γ positive T cell clones was achieved (48.1%). Natural killer T (NKT) lymphocytes increased significantly in all treated patients.CONCLUSIONS:Immune regulation of the anti-HBV immune response via p.o. administration of HBV envelope proteins alleviated the immune-mediated liver injury while augmenting the effective antiviral immunity.

Induction of oral immune regulation towards liver-extracted proteins for treatment of chronic HBV and HCV hepatitis: results of a phase I clinical trial

Abstract: 
Background: Anti‐viral immunity can be modulated via oral feeding of viral proteins. Hepatitis B and C viral (HBV, HCV)‐associated hepatocellular injury is mediated by a defective host anti‐viral immune response.

Immunomodulatory effects of plasminogen activators on hepatic fibrogenesis

Tissue‐type plasminogen activators (tPA) and urokinase‐type plasminogen activators (uPA) are involved in liver repair. We examined the potential immunomodulatory actions of uPA, tPA and uPA‐receptor (uPAR) in carbon‐tetrachloride‐induced hepatic fibrosis in wild‐type (WT), tPA−/−, uPA−/− and uPAR−/− mice. Carbon‐tetrachloride treatment increased fibrosis in four groups but significantly less in three knock‐out models. Serum cytokines and intrahepatic T cells elevated significantly following fibrosis process in WT animals but not in the knock‐out groups. In culture, uPA increased lymphocyte proliferation significantly in WT and uPA−/− but not uPAR−/− animals. Following uPA exposure in vivo, there was CD8 predominance. To isolate uPAs effect on lymphocytes, WT mice were irradiated sublethally and then reconstituted with WT or uPA−/− lymphocytes. In these animals fibrosis was decreased and T cells were reduced in the uPA−/− recipients. Based on these data we postulate that plasminogen activators affect fibrosis in part by liver‐specific activation of CD8 subsets that govern the fibrogenic activity of hepatic stellate cells.

Original contributionTreatment of chronic hepatitis B virus infection via oral immune regulation toward hepatitis B virus proteins

Treatment of chronic hepatitis B virus infection via oral immune regulation toward hepatitis B virus proteins