The Hepatic Microcirculation in Experimental Cirrhosis a Scanning Electron Microscopy Study of Microcorrosion Casts

The experimental model of liver cirrhosis induced by intragastric administration of CCl4 reproduces not only the histological picture of the postnecrotic cirrhosis but also its pathophysiological features. Corrosion casts of livers affected by CCl4-induced cirrhosis show the loss of the lobular pattern. Once the cirrhosis has completely developed, the whole microvascular bed appears to be composed of groups of sinusoid nodules of diameters varying between 0.3 and 1.5 mm.. Pre- and post-sinusoidal vessels and anastomoses between the former and the latter are mainly located at the perinodular spaces. This microvascular situation modifies the normal perfusion gradient within the parenchyma. Nevertheless, it can allow a still viable function

Vasopressin regulates the growth of the biliary epithelium in polycystic liver disease

The neurohypophysial hormone arginine vasopressin (AVP) acts by three distinct receptor subtypes: V1a, V1b, and V2. In the liver, AVP is involved in ureogenesis, glycogenolysis, neoglucogenesis and regeneration. No data exist about the presence of AVP in the biliary epithelium. Cholangiocytes are the target cells in a number of animal models of cholestasis, including bile duct ligation (BDL), and in several human pathologies, such as polycystic liver disease characterized by the presence of cysts that bud from the biliary epithelium. In vivo, liver fragments from normal and BDL mice and rats as well as liver samples from normal and ADPKD patients were collected to evaluate: (i) intrahepatic bile duct mass by immunohistochemistry for cytokeratin-19; and (ii) expression of V1a, V1b and V2 by immunohistochemistry, immunofluorescence and real-time PCR. In vitro, small and large mouse cholangiocytes, H69 (non-malignant human cholangiocytes) and LCDE (human cholangiocytes from the cystic epithelium) were stimulated with vasopressin in the absence/presence of AVP antagonists such as OPC-31260 and Tolvaptan, before assessing cellular growth by MTT assay and cAMP levels. Cholangiocytes express V2 receptor that was upregulated following BDL and in ADPKD liver samples. Administration of AVP increased proliferation and cAMP levels of small cholangiocytes and LCDE cells. We found no effect in the proliferation of large mouse cholangiocytes and H69 cells. Increases were blocked by preincubation with the AVP antagonists. These results showed that AVP and its receptors may be important in the modulation of the proliferation rate of the biliary epithelium

Vasopressin induces cholangiocyte proliferation in experimental cholestasis and in Polycystic Liver Disease

The hormone vasopressin (hereafter AVP) is a neuropeptide mainly synthesized in the brain’s hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei, works by three distinct receptor subtypes: V1a, V1b, and V2 [1]. In liver, AVP is involved in glycogenolysis and neoglucogenesis and regenerative processes [2]. Cholangiocytes are the cells that line the biliary ducts and they are the target in a number of animal models of cholestasis including bile duct ligation (BDL) and in several human pathologies such as polycystic liver disease (PLD) characterized by the presence of numerous cysts within the liver that arise from biliary epithelium [3]. Since no data exist about the presence and the role of AVP and receptors in biliary epithelium, we aimed to evaluate the effects of AVP in experimental model of cholestasis and in course of PLD. In vivo, normal and BDL liver fragments from rats, normal and PLD from human patients were collected to evaluate: (i) intrahepatic bile duct mass (IBDM) by immunohistochemistry for citokeratin-19 (CK-19); and (ii) expression of V1a, V1b and V2 by immunohistochemistry, immunofluorescence and real time PCR. In vitro, small and large mouse cholangiocytes, H69 (non-malignant human cholangiocytes) and LCDE (human cholangiocytes from cystic epithelium) were stimulated with AVP in the absence/presence of antagonists such as OPC-31260 and Tolvaptan, before assessing cellular growth by MTT proliferation assay, cAMP levels by a RIA kit and the expression of some angiogenic factors, such as platelet-derived growth factor (PDGF) and Angiopoietins (Ang-1 and Ang-2). Cholangiocytes express V2 receptor that was upregulated following BDL and in course of polycystic disease. Treatment with AVP of cholangiocyte cultures increased proliferation, cAMP levels and expression of PDGF, Ang-1, Ang-2 in small cholangiocytes and LCDE cells. These increments were blocked by pre-incubation with the AVP antagonists. Our results showed that AVP play an important role in growth of the biliary epithelium during cholestasis and in cystic epithelium in course of PLD acting on the cAMP signalling pathway and increasing angiogenic factors. Additional studies are necessary, but these first results may be considered important in the regulation of the biliary growth/loss in course of cholangiopathies

Role of Cassia angustifolia on hepatic toxicity in Wistar rats

Background. Cassia angustifolia L. (senna) is traditionally used as a laxative for the short-term treatment of acute constipation and as a purgative before diagnostic endoscopy. Among several adverse reactions in literature, hepatotoxicity (Sonmez et al., Gastroenterol. Belg., 2005;68:385-7) and portal vein thrombosis (Soyuncu et al., Clin. Toxicol. Phila, 2008;46:774-7) have been reported. Present study was aimed to evaluate the long-term effects of C. angustifolia by both in vivo (oral administration to rats) and in vitro (liver cell cultures) approaches. Materials and methods. In vivo, experiments were performed in Wistar rats, after oral administration of senna leaf extract (12 and 58 mg/kg/day) for 4 or 8 weeks. Serum was used for biochemical analysis. Liver samples were used for hystomorphological and immunohistochemical examination (Gaudio E. et al., Gastroenterology. 2006;130:1270-82) along with the determination of oxidative stress parameters. Cytotoxicity was assessed on Buffalo normal Rat Liver cell line (BRL-3A) by the Trypan blue assay and the MTT reduction method after 24 h of exposure. Results. In Wistar rats the extract did not induce any significant change in animal body weight, food and water consumption, enzyme activities, hystomorphological hepatic characteristics, levels of reduced glutathione, and MDA formation, at either time or dosage level. In BRL-3A cells the substance induced concentration-dependent cytotoxicity. Conclusions. C. angustifolia, at doses about 10 and 50 times higher than those used in humans (during a lapse of time corresponding to a chronic administration) does not affect liver morphology and hepatic function indices in rats. In vitro senna extract is cytotoxic at concentrations at least 2000 fold higher than those obtainable in vivo. Nevertheless, in humans the safety of C. angustifolia should be further monitored, in terms of patient-related factors

Gonadotropin-releasing hormone induces biliary proliferation by both paracrine and autocrine mechanisms

During cholestatic liver disease, there is dysregulation in the balance between biliary growth and loss. In bile ductligated (BDL) rats, this balance is modulated by neuroendocrine peptides via autocrine/paracrine pathways (1). Gonadotropinreleasing hormone (GnRH) is a trophic peptide hormone that modulates reproduc- tive function and proliferation in many cell types (2). We evaluated the autocrine role of GnRH in the regulation of cholangiocyte growth. The expression of GnRH receptors was evaluated in a normal mouse cholangiocyte cell line (NMC), sham and BDL rats. The effect of GnRH administration was evaluated in normal rats and in NMC. GnRH-induced biliary proliferation was evaluated by changes in intrahepatic bile duct mass (IBDM) by CK19 specific staining, the expression of proliferation and function markers. The expression and secretion of GnRH in NMC and isolated cholangiocytes was assessed. GnRH receptor subtypes GnRHR1 and GnRHR2 were expressed in biliary epithelium. Treatment with GnRH increased IBDM as well as proliferation and function markers in cholangiocytes. Transient knockdown and pharmacologic inhibition of GnRHR1 in NMC decreased proliferation. BDL cholangiocytes had increased expression of GnRH compared with normal rats, accompanied by increased GnRH secretion. In vivo and in vitro knockdown of GnRH decreased intrahepatic bile duct mass/cholangiocyte proliferation and fibrosis. GnRH secreted by cholangiocytes promotes biliary proliferation via an autocrine pathway. Disruption of GnRH/ GnRHR signaling may be important for the management of cholestatic liver diseases

Follicle-Stimulating Hormone influences biliary epithelium growth in Autosomal Dominant Polycystic Kidney Disease

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a genetic disorder characterized by the development of renal cysts and various extrarenal manifestations, such as hepatic cysts that bud from biliary epithelium (Alvaro et al., 2008; Onori et al., 2010). We previously showed that Follicle-Stimulating Hormone (FSH) is a trophic factor for the biliary cells in normal rat and in experimental model of bile duct ligation. (Mancinelli et al, 2009). From these data, we aimed to investigate the role of FSH on biliary epithelium in ADPKD. In vivo evaluation of FSH receptor, FSH, p-ERK and c-myc expression in liver fragments from normal and ADPKD patients and in vitro PCNA and cAMP levels in normal human cholangiocytes (H69) and in a cell line obtained from the epithelium lining the hepatic cysts (LCDE) was performed. We found that FSH induces the proliferation of the cystic epithelium and co-localize with p-ERK and c-myc, proteins activated in cAMP signalling mechanism. In vitro FSH sustains cellular growth by the activation of cAMP/ERK signalling pathway with or without the transient silencing of the FSH gene in LCDE by siRNA. These results indicate that FSH has an important role in cystic growth via the cAMP pathway. FSH candidates as a possible target for medical therapy of hepatic cysts during ADPKD

Effect of secretin on biliary epithelium growth by regulating expression of MicroRNA 125b and MicroRNA let7a in mice

Proliferating cholangiocytes have the capacity to respond and secrete several hormones and neuropeptides, including secretin (Onori et al., 2010). We investigated whether secretin secreted by S cells and cholangiocytes increases biliary proliferation in mice. Cholestasis was induced in secretin knockout (Sct-/-) and wild-type (control) mice by bile duct ligation (BDL) (Glaser et al., 2009). After 7 days of BDL, control and Sct-/- mice received tail-vein injections of morpholinos against microRNA 125b or let7a. One week later, liver tissues and cholangiocytes were collected and immunohistochemical, immunoblot, and real-time polymerase chain reaction assays were performed. Intrahepatic bile duct mass (IBDM) and proliferation were evaluated. Secretin secretion was measured in conditioned media from cholangiocytes and S cells. Secretin secretion was increased in supernatants from cholangiocytes and S cells after BDL in control mice. BDL Sct-/- mice had lower IBDM, reduced proliferation, and reduced production of VEGF and NGF compared with BDL control. BDL and control mice given morpholinos against microRNA 125b or let7a had increased IBDM, expression of VEGFA and NGF. Secretin regulated VEGF and NGF expression that negatively correlated with microRNA 125b and let7a levels in liver tissue. After liver injury, secretin produced by cholangiocytes and S cells reduces microRNA 125b and let7a levels, resulting in up-regulation of VEGF and NGF. Modulation of cholangiocyte expression of secretin could be a therapeutic approach for biliary diseases

Bioinformatics in Italy: BITS2011, the Eighth Annual Meeting of the Italian Society of Bioinformatics

The BITS2011 meeting, held in Pisa on June 20-22, 2011, brought together more than 120 Italian researchers working in the field of Bioinformatics, as well as students in Bioinformatics, Computational Biology, Biology, Computer Sciences, and Engineering, representing a landscape of Italian bioinformatics research