Optimization of Statin-Loaded Delivery Nanoparticles for Treating Chronic Liver Diseases by Targeting Liver Sinusoidal Endothelial Cells.

In this study, we developed functionalized polymeric micelles (FPMs) loaded with simvastatin (FPM-Sim) as a drug delivery system to target liver sinusoidal endothelial cells (LSECs) for preserving liver function in chronic liver disease (CLD). Polymeric micelles (PMs) were functionalized by coupling peptide ligands of LSEC membrane receptors CD32b, CD36 and ITGB3. Functionalization was confirmed via spectroscopy and electron microscopy. In vitro and in vivo FPM-Sim internalization was assessed by means of flow cytometry in LSECs, hepatocytes, Kupffer and hepatic stellate cells from healthy rats. Maximum tolerated dose assays were performed in healthy mice and efficacy studies of FPM-Sim were carried out in bile duct ligation (BDL) and thioacetamide (TAA) induction rat models of cirrhosis. Functionalization with the three peptide ligands resulted in stable formulations with a greater degree of in vivo internalization in LSECs than non-functionalized PMs. Administration of FPM-Sim in BDL rats reduced toxicity relative to free simvastatin, albeit with a moderate portal-pressure-lowering effect. In a less severe model of TAA-induced cirrhosis, treatment with FPM-CD32b-Sim nanoparticles for two weeks significantly decreased portal pressure, which was associated with a reduction in liver fibrosis, lower collagen expression as well as the stimulation of nitric oxide synthesis. In conclusion, CD32b-FPM stands out as a good nanotransporter for drug delivery, targeting LSECs, key inducers of liver injury.

Proteomic Analysis of Dysfunctional Liver Sinusoidal Endothelial Cells Reveals Substantial Differences in Most Common Experimental Models of Chronic Liver Diseases.

Molecular markers of dedifferentiation of dysfunctional liver sinusoidal endothelial cells (LSEC) have not been fully elucidated. We aimed at deciphering the molecular profile of dysfunctional LSEC in different pathological scenarios. Flow cytometry was used to sort CD11b-/CD32b+ and CD11b-/CD32b- LSEC from three rat models of liver disease (bile duct ligation-BDL; inhaled carbon tetrachloride-CCl4; and high fat glucose/fructose diet-HFGFD). A full proteomic profile was performed applying nano-scale liquid chromatography tandem mass spectrometry (nLC-MS) and analyzed with PEAKS software. The percentage of CD32b- LSEC varied across groups, suggesting different capillarization processes. Both CD32+ and CD32b- LSEC from models are different from control LSEC, but differently expressed proteins in CD32b- LSEC are significantly higher. Heatmaps evidenced specific protein expression patterns for each model. Analysis of biological significance comparing dysfunctional CD32b- LSEC with specialized CD32b+ LSEC from controls showed central similarities represented by 45 common down-regulated proteins involved in the suppression of the endocytic machinery and 63 common up-regulated proteins associated with the actin-dependent cytoskeleton reorganization. In summary; substantial differences but also similarities in dysfunctional LSEC from the three most common models of liver disease were found, supporting the idea that LSEC may harbor different protein expression profiles according to the etiology or disease stage.

Smart and eco-friendly N-isopropylacrylamide and cellulose hydrogels as a safe dual-drug local cancer therapy approach.

Local cancer treatment by in situ injections of thermo-responsive hydrogels (HG) offers several advantages over conventional systemic anti-cancer treatments. In this work, a biodegradable and multicompartmental HG composed of N-isopropylacrylamide, cellulose, citric acid, and ceric ammonium nitrate was developed for the controlled release of hydrophilic (doxorubicin) and hydrophobic (niclosamide) drugs. The formulation presented ideal properties regarding thermo-responsiveness, rheological behavior, drug release profile, biocompatibility, and biological activity in colon and ovarian cancer cells. Cellulose was found to retard drugs release rate, being only 4 % of doxorubicin and 30 % of niclosamide released after 1 week. This low release was sufficient to cause cell death in both cell lines. Moreover, HG demonstrated a proper injectability, in situ prevalence, and safety profile in vivo. Overall, the HG properties, together with its natural and eco-friendly composition, create a safe and efficient platform for the local treatment of non-resectable tumors or tumors requiring pre-surgical adjuvant therapy.

A Nine-Strain Bacterial Consortium Improves Portal Hypertension and Insulin Signaling and Delays NAFLD Progression In Vivo.

The gut microbiome has a recognized role in Non-alcoholic fatty liver disease (NAFLD) and associated comorbidities such as Type-2 diabetes and obesity. Stool transplantation has been shown to improve disease by restoring endothelial function and insulin signaling. However, more patient-friendly treatments are required. The present study aimed to test the effect of a defined bacterial consortium of nine gut commensal strains in two in vivo rodent models of Non-alcoholic steatohepatitis (NASH): a rat model of NASH and portal hypertension (PHT), and the Stelic animal (mouse) model (STAM™). In both studies the consortium was administered orally q.d. after disease induction. In the NASH rats, the consortium was administered for 2 weeks and compared to stool transplant. In the STAM™ study administration was performed for 4 weeks, and the effects compared to vehicle or Telmisartan at the stage of NASH/early fibrosis. A second group of animals was followed for another 3 weeks to assess later-stage fibrosis. In the NASH rats, an improvement in PHT and endothelial function was observed. Gut microbial compositional changes also revealed that the consortium achieved a more defined and richer replacement of the gut microbiome than stool transplantation. Moreover, liver transcriptomics suggested a beneficial modulation of pro-fibrogenic pathways. An improvement in liver fibrosis was then confirmed in the STAM™ study. In this study, the bacterial consortium improved the NAFLD activity score, consistent with a decrease in steatosis and ballooning. Serum cytokeratin-18 levels were also reduced. Therefore, administration of a specific bacterial consortium of defined composition can ameliorate NASH, PHT, and fibrosis, and delay disease progression.

Synergic effect of atorvastatin and ambrisentan on sinusoidal and hemodynamic alterations in a rat model of NASH.

In non-alcoholic steatohepatitis (NASH), decreased nitric oxide and increased endothelin-1 (ET-1, also known as EDN1) released by sinusoidal endothelial cells (LSEC) induce hepatic stellate cell (HSC) contraction and contribute to portal hypertension (PH). Statins improve LSEC function, and ambrisentan is a selective endothelin-receptor-A antagonist. We aimed to analyse the combined effects of atorvastatin and ambrisentan on liver histopathology and hemodynamics, together with assessing the underlying mechanism in a rat NASH model. Diet-induced NASH rats were treated with atorvastatin (10 mg/kg/day), ambrisentan (30 mg/kg/day or 2 mg/kg/day) or a combination of both for 2 weeks. Hemodynamic parameters were registered and liver histology and serum biochemical determinations analysed. Expression of proteins were studied by immunoblotting. Conditioned media experiments were performed with LSEC. HSCs were characterized by RT-PCR, and a collagen lattice contraction assay was performed. Atorvastatin and ambrisentan act synergistically in combination to completely normalize liver hemodynamics and reverse histological NASH by 75%. Atorvastatin reversed the sinusoidal contractile phenotype, thus improving endothelial function, whereas ambrisentan prevented the contractile response in HSCs by blocking ET-1 response. Additionally, ambrisentan also increased eNOS (also known as Nos3) phosphorylation levels in LSEC, via facilitating the stimulation of endothelin-receptor-B in these cells. Furthermore, the serum alanine aminotransferase of the combined treatment group decreased to normal levels, and this group exhibited a restoration of the HSC quiescent phenotype. The combination of atorvastatin and ambrisentan remarkably improves liver histology and PH in a diet-induced NASH model. By recovering LSEC function, together with inhibiting the activation and contraction of HSC, this combined treatment may be an effective treatment for NASH patients.

Steatosis as main determinant of portal hypertension through a restriction of hepatic sinusoidal area in a dietary rat nash model.

BACKGROUND & AIMS: Portal hypertension (PH) can be present in pre-cirrhotic stages, even in absence of fibrosis in non-alcoholic steatohepatitis (NASH) patients. Liver endothelial dysfunction (ED) has been shown as responsible for this effect in short-term dietary animal models. We evaluated the persistence of PH and underlying mechanisms in a long-term rat model of NASH. METHODS: Sprague-Dawley rats were fed 8 or 36 weeks with control diet or high-fat high-glucose/fructose diet. Metabolic parameters, histology, ED and haemodynamics were characterized. Structural characteristics of liver sections were analysed using image analysis. RESULTS: Both interventions reproduced NASH histological hallmarks (with steatosis being particularly increased at 36 weeks), but neither induced fibrosis. The 36-week intervention induced a significant increase in portal pressure (PP) compared to controls (12.1 vs 8.7 mmHg, P < .001) and the 8-week model (10.7 mmHg, P = .006), but all features of ED were normalized at 36 weeks. Image analysis revealed that the increased steatosis at 36-week was associated to an increase in hepatocyte area and a significant decrease in the sinusoidal area, which was inversely correlated with PP. The analysis provided a critical sinusoidal area above which animals were protected from developing PH and below which sinusoidal flux was compromised and PP started to increase. CONCLUSION: Liver steatosis per se (in absence of fibrosis) can induce PH through a decrease in the sinusoidal area secondary to the increase in hepatocyte area in a long-term diet-induced rat model of NASH. Image analysis of the sinusoidal area might predict the presence of PH.

Simvastatin-loaded polymeric micelles are more effective and less toxic than conventional statins in a pre-clinical model of advanced chronic liver disease.

Chronic liver disease (CLD) has no effective treatments apart from reducing its complications. Simvastatin has been tested as vasoprotective drug in experimental models of CLD showing promising results, but also limiting adverse effects. Two types of Pluronic® carriers loading simvastatin (PM108-simv and PM127-simv) as a drug delivery system were developed to avoid these toxicities while increasing the therapeutic window of simvastatin. PM127-simv showed the highest rates of cell internalization in rat liver sinusoidal endothelial cells (LSECs) and significantly lower toxicity than free simvastatin, improving cell phenotype. The in vivo biodistribution was mainly hepatic with 50% of the injected PM found in the liver. Remarkably, after one week of administration in a model of CLD, PM127-simv demonstrated superior effect than free simvastatin in reducing portal hypertension. Moreover, no signs of toxicity of PM127-simv were detected. Our results indicate that simvastatin targeted delivery to LSEC is a promising therapeutic approach for CLD.

Restoration of liver sinusoidal cell phenotypes by statins improves portal hypertension and histology in rats with NASH.

Non-alcoholic steatohepatitis (NASH) is a common chronic liver disorder in developed countries, with the associated clinical complications driven by portal hypertension (PH). PH may precede fibrosis development, probably due to endothelial dysfunction at early stages of the disease. Our aim was to characterize liver sinusoidal endothelial cell (LSEC) dedifferentiation/capillarization and its contribution to PH in NASH, together with assessing statins capability to revert endothelial function improving early NASH stages. Sprague-Dawley rats were fed with high fat glucose-fructose diet (HFGFD), or control diet (CD) for 8 weeks and then treated with simvastatin (sim) (10 mg·kg-1·day-1), atorvastatin (ato) (10 mg·kg-1·day-1) or vehicle during 2 weeks. Biochemical, histological and hemodynamic determinations were carried out. Sinusoidal endothelial dysfunction was assessed in individualized sorted LSEC and hepatic stellate cells (HSC) from animal groups and in whole liver samples. HFGFD rats showed full NASH features without fibrosis but with significantly increased portal pressure compared with CD rats (10.47 ± 0.37 mmHg vs 8.30 ± 0.22 mmHg; p < 0.001). Moreover, HFGFD rats showed a higher percentage of capillarized (CD32b-/CD11b-) LSEC (8% vs 1%, p = 0.005) showing a contractile phenotype associated to HSC activation. Statin treatments caused a significant portal pressure reduction (sim: 9.29 ± 0.25 mmHg, p < 0.01; ato: 8.85 ± 0.30 mmHg, p < 0.001), NASH histology reversion, along with significant recovery of LSEC differentiation and a regression of HSC activation to a more quiescent phenotype. In an early NASH model without fibrosis with PH, LSEC transition to capillarization and HSC activation are reverted by statin treatment inducing portal pressure decrease and NASH features improvement.

Restoration of a healthy intestinal microbiota normalizes portal hypertension in a rat model of nonalcoholic steatohepatitis.

Portal hypertension (PH) drives most of the clinical complications in chronic liver diseases. However, its progression in nonalcoholic steatohepatitis (NASH) and its association with the intestinal microbiota (IM) have been scarcely studied. Our aim was to investigate the role of the IM in the mechanisms leading to PH in early NASH. The experimental design was divided in two stages. In stage 1, Sprague-Dawley rats were fed for 8 weeks a high-fat, high-glucose/fructose diet (HFGFD) or a control diet/water (CD). Representative rats were selected as IM donors for stage 2. In stage 2, additional HFGFD and CD rats underwent intestinal decontamination, followed by IM transplantation with feces from opposite-diet donors (heterologous transplant) or autologous fecal transplant (as controls), generating four groups: CD-autotransplanted, CD-transplanted, HFGFD-autotransplanted, HFGFD-transplanted. After IM transplantation, the original diet was maintained for 12-14 days until death. HFGFD rats developed obesity, insulin resistance, NASH without fibrosis but with PH, intrahepatic endothelial dysfunction, and IM dysbiosis. In HFGFD rats, transplantation with feces from CD donors caused a significant reduction of PH to levels comparable to CD without significant changes in NASH histology. The reduction in PH was due to a 31% decrease of intrahepatic vascular resistance compared to the HFGFD-autotransplanted group (P < 0.05). This effect occurs through restoration of the sensitivity to insulin of the hepatic protein kinase B-dependent endothelial nitric oxide synthase signaling pathway. CONCLUSION: The IM exerts a direct influence in the development of PH in rats with diet-induced NASH and dysbiosis; PH, insulin resistance, and endothelial dysfunction revert when a healthy IM is restored. (Hepatology 2018;67:1485-1498).

A Nitric Oxide-Donating Statin Decreases Portal Pressure with a Better Toxicity Profile than Conventional Statins in Cirrhotic Rats.

Statins present many beneficial effects in chronic liver disease, but concerns about safety exist. We evaluated the hepatic effects of a nitric oxide-releasing atorvastatin (NCX 6560) compared to conventional statins. Simvastatin, atorvastatin and NCX 6560 were evaluated in four-week bile duct-ligated rats (BDL) simulating decompensated cirrhosis and in thirteen-week carbon tetrachloride (CCl4) intoxicated rats, a model of early cirrhosis. In the BDL model, simvastatin treated rats showed high mortality and the remaining animals presented muscular and hepatic toxicity. At equivalent doses, NCX 6560 eliminated hepatic toxicity and reduced muscular toxicity (60-74%) caused by atorvastatin in the more advanced BDL model; toxicity was minimal in the CCl4 model. Atorvastatin and NCX 6560 similarly reduced portal pressure without changing systemic hemodynamics in both models. Atorvastatin and NCX 6560 caused a mild decrease in liver fibrosis and inflammation and a significant increase in intrahepatic cyclic guanosine monophosphate. NCX 6560 induced a higher intrahepatic vasoprotective profile (activated endothelial nitric oxide synthase and decreased platelet/endothelial cell adhesion molecule-1), especially in the CCl4 model, suggesting a higher benefit in early cirrhosis. In conclusion, NCX 6560 improves the liver profile and portal hypertension of cirrhotic rats similarly to conventional statins, but with a much better safety profile.

Correction: Gamma-Secretase-Dependent and -Independent Effects of Presenilin1 on ß-Catenin·Tcf-4 Transcriptional Activity.

[This corrects the article DOI: 10.1371/journal.pone.0004080.].

The renal effects of droxidopa are maintained in propranolol treated cirrhotic rats.

BACKGROUND & AIMS: Droxidopa improves hemodynamic and renal alterations of cirrhotic rats without changing portal pressure. We aimed to evaluate the effects of a combined treatment with droxidopa and non-selective beta-blockers or statins in order to decrease portal pressure, while maintaining droxidopa beneficial effects. METHODS: Acute studies combining droxidopa with carvedilol, propranolol or atorvastatin in four-week bile-duct ligated (BDL) rats and a chronic study combining propranolol and droxidopa for 5 days in CCl4 -cirrhotic rats were performed. Hemodynamic values were registered and biochemical parameters from blood and urine samples analyzed. RESULTS: Bile-duct ligated rats treated with carvedilol + droxidopa showed no changes in mean arterial pressure (MAP) and portal pressure (PP) compared to vehicles. Atorvastatin + droxidopa combination also failed to reduce PP, but maintained the beneficial increase in MAP and superior mesenteric artery resistance (SMAR) and decrease in blood flow (SMABF) caused by droxidopa. In contrast, the acute administration of propranolol + droxidopa significantly reduced PP maintaining a mild increase in MAP and improving, in an additive way, the decrease in SMABF and increase in SMAR caused by droxidopa. This combination also preserved droxidopa diuretic effect. When chronically administered to CCl4 -cirrhotic rats, propranolol + droxidopa caused a decrease in PP, a significant reduction in SMABF and an increase in SMAR. The combination did not alter liver function and droxidopa diuretic and natriuretic effect, and even improved free water clearance. CONCLUSION: Droxidopa could be effective for the renal alterations of cirrhotic patients on propranolol therapy and the combination of both drugs may balance the adverse effects of each treatment.

Inhibition of neuronal apoptosis and axonal regression ameliorates sympathetic atrophy and hemodynamic alterations in portal hypertensive rats.

BACKGROUND AND AIM: A neuronal pathway participates in the development of portal hypertension: blockade of afferent sensory nerves in portal vein ligated (PVL) rats simultaneously prevents brain cardiovascular regularory nuclei activation, neuromodulator overexpression in superior mesenteric ganglia, sympathetic atrophy of mesenteric innervation and hemodynamic alterations. Here we investigated in PVL rats alterations in neuromodulators and signaling pathways leading to axonal regression or apoptosis in the superior mesenteric ganglia and tested the effects of the stimulation of neuronal proliferation/survival by using a tyrosine kinase receptor A agonist, gambogic amide. RESULTS: The neuronal pathway was confirmed by an increased neuronal afferent activity at the vagal nodose ganglia and the presence of semaphorin3A in sympathetic pre-ganglionic neurons at the intermediolateral nucleus of the spinal cord of PVL rats. Expression of the active form of tyrosine kinase receptor A (phosphorylated), leading to proliferation and survival signaling, showed a significant reduction in PVL comparing to sham rats. In contrast, the apoptotic and axonal retraction pathways were stimulated in PVL, demonstrated by a significant overexpression of semaphorin 3A and its receptor neuropilin1, together with increases of cleaved caspase7, inactive poly(ADP-ribose) polymerase and Rho kinase expression. Finally, the administration of gambogic amide in PVL rats showed an amelioration of hemodynamic alterations and sympathetic atrophy, through the activation of survival pathways together with the inhibition of apoptotic cascades and Rho kinase mediated axonal regression. CONCLUSION: The adrenergic alteration and sympathetic atrophy in mesenteric vessels during portal hypertension is caused by alterations on neuromodulation leading to post-ganglionic sympathetic regression and apoptosis and contributing to splanchnic vasodilation.

Droxidopa, an oral norepinephrine precursor, improves hemodynamic and renal alterations of portal hypertensive rats.

UNLABELLED: We aimed to evaluate the effects of droxidopa (an oral synthetic precursor of norepinephrine) on the hemodynamic and renal alterations of portal hypertensive rats. Sham, portal vein-ligated (PVL), and 4-week biliary duct-ligated (BDL) rats received a single oral dose of droxidopa (25-50 mg/kg) or vehicle and hemodynamic parameters were monitored for 2 hours. Two groups of BDL and cirrhotic rats induced by carbon tetrachloride (CCl(4) ) were treated for 5 days with droxidopa (15 mg/kg, twice daily, orally); hemodynamic parameters and blood and urinary parameters were assessed. The droxidopa effect on the Rho kinase (RhoK) / protein kinase B (AKT) / endothelial nitric oxide synthase (eNOS) pathways was analyzed by western blot in superior mesenteric artery (SMA). The acute administration of droxidopa in PVL and BDL rats caused a significant and maintained increase in arterial pressure and mesenteric arterial resistance, with a significant decrease of mesenteric arterial and portal blood flow, without changing portal pressure and renal blood flow. Two-hour diuresis greatly increased. Carbidopa (DOPA decarboxylase inhibitor) blunted all effects of droxidopa. Chronic droxidopa therapy in BDL rats produced the same beneficial hemodynamic effects observed in the acute study, did not alter liver function parameters, and caused a 50% increase in 24-hour diuresis volume (7.4 ± 0.9 mL/100g in BDL vehicle versus 11.8 ± 2.5 mL/100g in BDL droxidopa; P = 0.01). Droxidopa-treated rats also showed a decreased ratio of p-eNOS/eNOS and p-AKT/AKT and increased activity of RhoK in SMA. The same chronic treatment in CCl(4) rats caused similar hemodynamic effects and produced significant increases in diuresis volume and 24-hour natriuresis (0.08 ± 0.02 mmol/100g in CCl(4) vehicle versus 0.23 ± 0.03 mmol/100g in CCl(4) droxidopa; P = 0.014). CONCLUSION: Droxidopa might be an effective therapeutic agent for hemodynamic and renal alterations of liver cirrhosis and should be tested in cirrhosis patients.

Blockage of the afferent sensitive pathway prevents sympathetic atrophy and hemodynamic alterations in rat portal hypertension.

BACKGROUND AND AIMS: Portal hypertension causes arterial vasodilation and sympathetic atrophy in the splanchnic area. We aimed to demonstrate a relationship between hemodynamic alterations and sympathetic atrophy by investigating a pathway from sensitive afferent signals to mesenteric sympathetic ganglia. METHODS: Experiments were conducted in sham and portal vein ligated (PVL) adult and neonatal rats treated with vehicle or capsaicin. Hemodynamic parameters, and immunohistochemistry, immunofluorescence and Western blot of different tissues were analysed. RESULTS: cFos expression in the brain supraoptic nuclei was used to confirm abrogation of the afferent signal in capsaicin-treated PVL rats (effectively afferent blocked). Neonatal and adult PVL afferent blocked rats showed simultaneous prevention of hemodynamic alterations and sympathetic atrophy (measured by tyrosine hydroxylase expression in nerve structures of splanchnic vasculature). Not effectively afferent blocked rats showed none of these effects, behaving as PVL vehicle. All capsaicin treated animals presented loss of calcitonin gene-related peptide in superior mesenteric artery and ganglia, whereas neuronal nitric oxide synthase remained unaffected. Neuronal markers semaphorin-3A, nerve growth factor, its precursor and p75 neurotrophic receptor, were significantly over-expressed in the PVL sympathetic ganglia compared with sham, but not in effectively afferent blocked rats. Semaphorin-3A staining in mesenteric ganglia co-localized with vesicular acetylcholine transporter, but not with adrenergic, nitrergic and sensory axons, suggesting that semaphorin-3A might originate in preganglionic neurons. CONCLUSION: These results indicate that the nervous system has a central role in the genesis of the circulatory abnormalities of portal hypertension, and support that mesenteric sympathetic atrophy contributes to splanchnic arterial vasodilation.

Physiopathology of splanchnic vasodilation in portal hypertension.

In liver cirrhosis, the circulatory hemodynamic alterations of portal hypertension significantly contribute to many of the clinical manifestations of the disease. In the physiopathology of this vascular alteration, mesenteric splanchnic vasodilation plays an essential role by initiating the hemodynamic process. Numerous studies performed in cirrhotic patients and animal models have shown that this splanchnic vasodilation is the result of an important increase in local and systemic vasodilators and the presence of a splanchnic vascular hyporesponsiveness to vasoconstrictors. Among the molecules and factors known to be potentially involved in this arterial vasodilation, nitric oxide seems to have a crucial role in the physiopathology of this vascular alteration. However, none of the wide variety of mediators can be described as solely responsible, since this phenomenon is multifactorial in origin. Moreover, angiogenesis and vascular remodeling processes also seem to play a role. Finally, the sympathetic nervous system is thought to be involved in the pathogenesis of the hyperdynamic circulation associated with portal hypertension, although the nature and extent of its role is not completely understood. In this review, we discuss the different mechanisms known to contribute to this complex phenomenon.

Atrophy of mesenteric sympathetic innervation may contribute to splanchnic vasodilation in rat portal hypertension.

BACKGROUND AND AIMS: Portal hypertension is associated with downregulation of mRNA and proteins involved in adrenergic transmission in the superior mesenteric artery (SMA) in portal vein-ligated (PVL) and cirrhotic rats. We aimed to investigate whether SMA adrenergic dysfunction was accompanied by sympathetic nerve structural changes and whether it was extensive to resistance mesenteric arteries. We also attempted to localize the origin of mRNA of specific adrenergic genes. METHODS AND RESULTS: In situ hybridization showed tyrosine hydroxylase (Th) mRNA expression in neuronal bodies of superior mesenteric ganglia and inside axonal fibres surrounding proximal SMA sections. Comparison of SMA by Th immunohistochemistry, both in PVL and bile duct-ligated (BDL) rats, demonstrated a significant decrease in the number of nervous structures (69% PVL; 62% BDL), total nervous area (70% PVL; 52% BDL) and Th-stained nervous area (89% PVL; 64% BDL) compared with sham rats. A strong correlation was detected between the Th-stained nervous area and the haemodynamic parameters, mainly with SMA resistance (r=0.9, P<0.001 for PVL and r=0.75, P=0.018 for BDL). Western blot analysis of Th, dopamine beta-hydroxylase and synaptosome-associated protein of 25 kDa indicated a significant inhibition in protein expression (35-58%) in mesenteric resistance arteries from both portal hypertension models compared with sham. By contrast, nervous structure analysis and protein expression in renal arteries showed no differences between sham and PVL rats. CONCLUSION: Portal hypertension is associated with sympathetic nerve atrophy/regression in the mesenteric arterial vasculature that could contribute to the splanchnic vasodilation associated with portal hypertension.

Gamma-secretase-dependent and -independent effects of presenilin1 on beta-catenin.Tcf-4 transcriptional activity.

Presenilin1 (PS1) is a component of the gamma-secretase complex mutated in cases of Familial Alzheimer's disease (FAD). PS1 is synthesized as a 50 kDa peptide subsequently processed to two 29 and 20 kDa subunits that remain associated. Processing of PS1 is inhibited by several mutations detected in FAD patients. PS1 acts as negative modulator of beta-catenin.Tcf-4 transcriptional activity. In this article we show that in murine embryonic fibroblasts (MEFs) the mechanisms of action of the processed and non-processed forms of PS1 on beta-catenin.Tcf-4 transcription are different. Whereas non-processed PS1 inhibits beta-catenin.Tcf-4 activity through a mechanism independent of gamma-secretase and associated with the interaction of this protein with plakoglobin and Tcf-4, the effect of processed PS1 is prevented by gamma-secretase inhibitors, and requires its interaction with E- or N-cadherin and the generation of cytosolic terminal fragments of these two cadherins, which in turn destabilize the beta-catenin transcriptional cofactor CBP. Accordingly, the two forms of PS1 interact differently with E-cadherin or beta-catenin and plakoglobin: whereas processed PS1 binds E-cadherin with high affinity and beta-catenin or plakoglobin weakly, the non-processed form behaves inversely. Moreover, contrarily to processed PS1, that decreases the levels of c-fos RNA, non-processed PS1 inhibits the expression c-myc, a known target of beta-catenin.Tcf-4, and does not block the activity of other transcriptional factors requiring CBP. These results indicate that prevention of PS1 processing in FAD affects the mechanism of repression of the transcriptional activity dependent on beta-catenin.

Down-regulation of genes related to the adrenergic system may contribute to splanchnic vasodilation in rat portal hypertension.

BACKGROUND/AIMS: Splanchnic vasodilation initiates the hyperdynamic syndrome in portal hypertension. We aimed to explore molecular mechanisms involved in the development of mesenteric vasodilation in portal hypertension. METHODS: Superior mesenteric artery (SMA) samples from portal vein ligated (PVL) and sham rats were compared in a time course experiment using DNA microarrays. Selected genes were quantified by qRT-PCR in PVL and cirrhotic rats. Inmunohistochemistry of tyrosine hydroxylase (Th) and norepinephrine was assessed in SMA sections of PVL and sham rats. Western blot analysis of Th, dopamine beta-hydroxylase (Dbh) and synaptosome-associated protein (Snap-25) was performed in SMA and jejunum samples from the animal models. RESULTS: Fifty differentially expressed genes implicated in neurotransmission, especially adrenergic, were detected in SMA samples from PVL rats. Sequential analysis showed a profound down-regulation at 14 days in PVL rats. These down-regulated genes were confirmed by RT-PCR in SMA from PVL and cirrhotic rats. Th and NE detection by immunohistochemistry was reduced in PVL compared to sham. Th, Dbh and Snap-25 expression was lower in SMA from 14-day PVL and cirrhotic rats compared to sham and control rats, respectively. CONCLUSIONS: Genetic down-regulation of genes related to the adrenergic system might have a role in splanchnic vasodilation of portal hypertension.