Aggregates Dramatically Alter Fibrin Ultrastructure.

Among the many factors influencing fibrin formation and structure (concentration, temperature, composition, pH, etc.), it has been suggested that the polydispersity of fibrinogen may play an important role. We propose here a detailed investigation of the influence of this parameter on fibrin multiscale structure. Two commercial fibrinogen preparations were used, a monodisperse and a polydisperse one. First, the respective compositions of both fibrinogen preparations were thoroughly determined by measuring the fibrin-stabilizing factor; fibronectin; α, ß, and γ intact chain contents; the γ/γ' chains ratio; the N-glycosylation; and the post-translational modifications. Slight variations between the composition of the two fibrinogen preparations were found that are much smaller than the compositional variations necessary to alter significantly fibrin multiscale structure as observed in the literature. Conversely, multiangle laser light scattering-coupled size exclusion chromatography and dynamic light scattering measurements showed that the polydisperse preparation contains significant amounts of aggregates, whereas the other preparation is essentially monodisperse. The multiscale structure of the fibrins produced from those two fibrinogen preparations was determined by using x-ray scattering, spectrophotometry, and confocal microscopy. Results show that fibers made from the aggregate-free fibrinogen present a crystalline longitudinal and lateral structure and form a mikado-like network. The network produced from the aggregates containing fibrinogen looks to be partly built around bright spots that are attributed to the aggregate. The multiscale structure of mixtures between the two preparations shows a smooth evolution, demonstrating that the quantity of aggregates is a major determining factor for fibrin multiscale structure. Indeed, the effect of a few percent in the mass of aggregates is larger than any other effect because of compositional differences under the same reaction conditions. Finally, we propose a mechanistic interpretation of our results, which points at a direct role of the aggregates during polymerization, which disrupts the ideal ordering of monomers inside fibrin protofibrils and fibers.

Gene- and exon-expression profiling reveals an extensive LPS-induced response in immune cells in patients with cirrhosis.

BACKGROUND & AIMS: Lipopolysaccharide (LPS)-expressing bacteria cause severe inflammation in cirrhotic patients. The global gene response to LPS is unknown in cirrhotic immune cells. METHODS: Gene-expression profiling using Affymetrix Human Exon Array analyzed the expression of 14,851 genes in LPS-stimulated peripheral blood mononuclear cells (PBMCs) from 4 patients with cirrhosis and 4 healthy subjects. We performed validation studies using RT-qPCR in LPS-stimulated PBMCs from 52 patients and 9 healthy subjects and investigated the association of gene induction with mortality in 26 patients. RESULTS: Gene-expression profiling of LPS-stimulated cirrhotic cells showed 509 upregulated genes and 1588 downregulated genes. In LPS-stimulated "healthy" cells, 952 genes were upregulated and 838 genes downregulated. The 741 LPS-regulated genes shared by cirrhotic and "healthy" cells were involved in cytokine production/activity and induction of "immune paralysis". Comparison of functions associated with the 1356 genes, specifically regulated by LPS in cirrhotic cells, to functions of the 1049 genes, specifically regulated in "healthy" cells, allowed to define a cirrhosis-specific phenotype. Unlike in "healthy" cells, LPS failed to induce an interferon-mediated program in cirrhotic cells. In cirrhotic PBMCs, LPS specifically induced certain molecules involved in apoptosis and downregulated molecules involved in endocytic trafficking. RT-qPCR experiments showed that LPS-stimulated cirrhotic PBMCs had an enhanced induction of certain proinflammatory cytokines and chemokines. In the prognosis study, higher ex vivo LPS-induction of the inflammatory genes IL6 and CXCL5 was a significant predictor of mortality. CONCLUSIONS: Our results show that LPS-stimulated cirrhotic PBMCs exhibit an extensive and often unexpected transcriptional response.

Glycogen synthase kinase 3 involvement in the excessive proinflammatory response to LPS in patients with decompensated cirrhosis.

BACKGROUND & AIMS: In decompensated cirrhosis, the early innate immune response to the Toll-like receptor 4 (TLR4) agonist, lipopolysaccharides (LPS), is characterized by a hyper-production of pro-inflammatory cytokines and hypo-production of the anti-inflammatory cytokine IL-10. In LPS-stimulated non-cirrhotic immune cells, the constitutively active glycogen synthase kinase (GSK) 3 favors pro- vs. anti-inflammatory cytokines, by acting on gene induction. However, in these cells, TLR4 dampens its own pro-inflammatory response by inducing early (within minutes) AKT-mediated phosphorylation of GSK3ß (one of two GSK3 isoforms) on Ser9. Phosphorylation of GSK3ß (Ser9) inhibits its activity, decreases pro-inflammatory cytokines, and increases IL-10. Thus, we investigated the role of GSK3 in LPS-induced cytokine production by peripheral blood mononuclear cells (PBMCs) or monocytes from patients with advanced cirrhosis and normal subjects. METHODS: Cells were pre-incubated with or without GSK3 inhibitor (SB216763 or lithium chloride) for 1h and then stimulated with LPS. Cytokine production was assessed at mRNA and secreted proteins levels, by real-time RT-PCR at 1h and ELISA at 20 h, respectively. GSK3ß phosphorylation was assessed using Western blotting. RESULTS: In cirrhotic and normal PBMCs pretreated with GSK3 inhibitors, LPS-induced production of pro-inflammatory proteins TNF-α and IL-12p40 was significantly decreased while that of IL-10 was increased. LPS-induced, AKT-mediated phosphorylation of GSK3ß on Ser9 found in normal monocytes, was abolished in cirrhotic cells. CONCLUSIONS: GSK3 is involved in the early TLR4-mediated pro-inflammatory response in patients with decompensated cirrhosis. This was associated with a defect in AKT-mediated GSK3ß phosphorylation resulting in unrestricted 'pro-inflammatory' activity of the enzyme.

In vivo hepatic endoplasmic reticulum stress in patients with chronic hepatitis C.

In hepatocytes, the accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes ER stress and the unfolded protein response (UPR), mediated by the ER-resident stress sensors ATF-6, IRE1, and PERK. UPR-responsive genes are involved in the fate of ER-stressed cells. Cells carrying hepatitis C virus (HCV) subgenomic replicons exhibit in vitro ER stress and suggest that HCV inhibits the UPR. Since in vivo ER homeostasis is unknown in livers with chronic HCV infection, we investigated ER stress and the UPR in liver samples from untreated patients with chronic hepatitis C (CHC), in comparison with normal livers. Electron microscopy, western blotting, and real-time RT-PCR were used in liver biopsy specimens. Electron microscopy identified features showing ER stress in hepatocyte samples from patients with CHC; however, 'ER-stressed' hepatocytes were found in clusters (3-5 cells) that were scattered in the liver parenchyma. Western blot analysis confirmed the existence of hepatic ER stress by showing activation of the three ER stress sensors ATF-6, IRE1, and PERK in CHC. Real-time RT-PCR showed no significant induction of UPR-responsive genes in CHC. In contrast, genes involved in the control of diffuse processes such as liver proliferation, inflammation, and apoptosis were significantly induced in CHC. In conclusion, livers from patients with untreated CHC exhibit in vivo hepatocyte ER stress and activation of the three UPR sensors without apparent induction of UPR-responsive genes. This lack of gene induction may be explained by the inhibiting action of HCV per se (as suggested by in vitro studies) and/or by our finding of the localized nature of hepatocyte ER stress.

Ex vivo effects of high-density lipoprotein exposure on the lipopolysaccharide-induced inflammatory response in patients with severe cirrhosis.

UNLABELLED: High-density lipoproteins (HDL) are known to neutralize lipopolysaccharide (LPS). Because patients with cirrhosis have lower HDL levels, this may contribute to LPS-induced ex vivo monocyte overproduction of proinflammatory cytokines. However, the effects of HDL on cytokine production by monocytes from patients with cirrhosis have never been studied. The aim of this study was to determine the effects of HDL on LPS-induced proinflammatory cytokine production in whole blood and isolated monocytes from patients with severe cirrhosis and controls. Plasma levels of HDL and cytokines were determined. The effects of reconstituted HDL (rHDL) on LPS-induced cytokine production in whole blood were assessed by cytokine array and on tumor necrosis factor alpha (TNF-alpha) and interleukin-10 (IL-10) production in isolated monocytes. Plasma HDL levels were significantly lower in patients with cirrhosis than in controls. Plasma levels of TNF-alpha and IL-6 were significantly higher in patients with cirrhosis than in controls. Incubation of rHDL with whole blood prevented LPS-induced TNF-alpha and IL-6 overproduction in patients with cirrhosis. LPS-induced TNF-alpha production and CD14 expression were significantly more marked in cirrhotic monocytes than in control monocytes, and both decreased significantly after rHDL incubation. LPS-induced down-regulation of scavenger receptor, class B, type I (SR-BI) expression was abolished in cirrhotic monocytes. CONCLUSIONS: This study shows that rHDL abolishes the LPS-induced overproduction of proinflammatory cytokines in whole blood from patients with severe cirrhosis. These results were confirmed in isolated monocytes from these patients. This suggests that administration of rHDL might be a useful strategy for the treatment of cirrhosis to limit LPS-induced cytokine overproduction.

[Argatroban in heparin-induced thrombocytopenia: A survey of prescribing practices and use in France]. / Argatroban et thrombopénie induite par l'héparine : observatoire des modalités de prescription et d'utilisation en France.

OBJECTIVE: A survey of prescribing practices was carried out in France to ensure that argatroban was used appropriately during the first 18months after it obtained marketing authorization for anticoagulation in adults with heparin-induced thrombocytopenia (HIT). METHODS: This observational study was proposed to public and private hospitals with at least 2 orders of argatroban. All patients who received at least one argatroban injection during the study period had to be included. Their demographic characteristics, the pathology causing heparin treatment, the indication of treatment with argatroban, as well as available real-life clinical and biological monitoring data were retrospectively collected. RESULTS: In the 23 participating centers, the drug was prescribed mainly by the following hospital units: surgery and intensive care (79.3%) (of which 18.3% cardiovascular), nephrology/hemodialysis (14.8%) and internal medicine (5.9%). Among the 169 patients included, with median age of 68 years, 118 (69.8%) had renal impairment (creatinine clearance <90mL/min). The HIT probability scoring and diagnostic tests used differed widely between the centers. The reasons for prescribing the drug were mainly suspected HIT (51.5%), declared confirmed HIT (21.3%) or a history of HIT (14.8%). Seventy-three (73) patients (43.2%) had thrombotic symptoms or a systemic reaction initially. The median initial dose prescribed was 0.5µg/kg/min (ranging from 0.05 to 4.42) and doses >2µg/kg/min were used during hemodialysis. More than half of the patients (58.6%) had no clinical complications. Most of the serious adverse reactions were hemorrhagic (11/12). CONCLUSION: This study illustrates the complexity of treatment for HIT and the need to be familiar with and follow guidelines on the management of HIT, especially for susceptible patients treated in intensive care units.

Protein array technology to investigate cytokine production by monocytes from patients with advanced alcoholic cirrhosis: An ex vivo pilot study.

AIM: In patients with advanced cirrhosis, little is known about the ability of peripheral blood monocytes to spontaneously produce signaling proteins such as cytokines. The aim of this ex vivo study was to evaluate cytokine production under baseline conditions and after stimulation by lipopolysaccharide (LPS), a toll-like receptor (TLR) agonist. METHODS: Peripheral blood monocytes were isolated from patients with advanced alcoholic cirrhosis (without ongoing bacterial infections) and normal subjects. Cells were left unstimulated or were stimulated with LPS. The abundance of 24 cytokines was measured using a filter-based, arrayed sandwich enzyme-linked immunosorbent assay (ELISA) in the supernatant of cultured monocytes. RESULTS: Cirrhotic monocytes spontaneously produced six proteins (TNF-alpha, IL-6, IL-8, MCP-1, RANTES and Gro), whereas normal monocytes produced only small amounts of IL-8 and RANTES. Analyses with the online gene set analysis toolkit WebGestalt (http://bioinfo.vanderbilt.edu/webgestalt) found enrichment for the six proteins in the human gene ontology subcategory (http://www.geneontology.org), Kyoto Encyclopedia of Genes and Genome pathways (http://www.genome.ad.jp/kegg/) and BioCarta pathways (http://www.biocarta.com/genes/index.asp) consistent with a proinflammatory phenotype of cirrhotic monocytes resulting from activated TLR signaling. Interestingly, LPS-elicited TLR engagement further increased the production of the six proteins and did not induce the secretion of any others, in particular the anti-inflammatory cytokine IL-10. LPS-stimulated normal monocytes produced TNF-alpha, IL-6, IL-8, MCP-1, RANTES, Gro and IL-10. CONCLUSION: In patients with advanced cirrhosis, peripheral blood monocytes spontaneously produce proinflammatory cytokines, presumably in response to unrestricted TLR signaling.

High-density lipoprotein administration attenuates liver proinflammatory response, restores liver endothelial nitric oxide synthase activity, and lowers portal pressure in cirrhotic rats.

UNLABELLED: In patients with cirrhosis, endotoxic shock is a major complication of portal hypertension, which is related partly to intrahepatic endothelial nitric oxide synthase (eNOS) down-regulation. High-density lipoproteins (HDLs), whose plasma levels are reduced in cirrhosis, have an anti-inflammatory effect by neutralizing circulating lipopolysaccharide (LPS), and they increase eNOS activity in endothelial cells. Therefore, the aim of this study was to assess the effects of reconstituted high-density lipoprotein (rHDL) administration on the LPS-induced proinflammatory response, intrahepatic eNOS regulation, and portal hypertension in cirrhotic rats. Cirrhotic and control rats were pretreated with rHDL or saline and challenged with LPS or saline. The neutralization of LPS in HDL was assessed by the measurement of HDL-bound fluorescent LPS levels. Plasma tumor necrosis factor alpha (TNFalpha) and lipopolysaccharide binding protein (LBP) levels were measured. The expression of hepatic TNFalpha, LBP, inducible nitric oxide synthase (iNOS), and caveolin-1 (a major eNOS inhibitor) and the activity of protein kinase B (Akt; a major eNOS activator) and eNOS were determined. The portal pressure was measured. The plasma HDL levels were significantly lower in cirrhotic rats than in control rats. In cirrhotic rats, the plasma levels of HDL-bound fluorescent LPS were 50% lower than those in controls, and they were restored after rHDL administration. The plasma TNFalpha levels were significantly higher in LPS-challenged cirrhotic rats than in controls and significantly decreased after rHDL administration. rHDL administration decreased hepatic TNFalpha, LBP, iNOS, and caveolin-1 expression, restored hepatic eNOS and Akt activity, and significantly lowered the portal pressure and intrahepatic vascular resistance. CONCLUSION: In cirrhotic rats, rHDL administration decreases the hepatic proinflammatory signals induced by LPS, restores the hepatic eNOS activity, and lowers the portal pressure. This suggests that the decrease in circulating HDL in cirrhosis plays a role in the excessive proinflammatory response and intrahepatic eNOS down-regulation.

Comparison of the immunogenicity of different therapeutic preparations of human factor VIII in the murine model of hemophilia A.

Von Willebrand factor (VWF) has been proposed to reduce the immunogenicity of therapeutic factor VIII (FVIII) in patients with hemophilia A. Using FVIII-deficient mice, we compared the immunogenicity of different preparations of plasma-derived (pd) and recombinant (r) FVIII. Treatment of mice with pdFVIII induced significantly lower titers of FVIII inhibitors, as measured by ELISA and in vitro coagulation assays, compared with rFVIII. Furthermore, pre-incubation of rFVIII with excess VWF significantly reduced rFVIII immunogenicity. Our data confirm that pdFVIII induces lower levels of inhibitors than rFVIII, and that VWF is an immuno-chaperone molecule for FVIII.

Human immunoglobulins in intraocular inflammation.

Chronic intraocular inflammation (IOI) is a heterogeneous group of rare diseases, which represents one of the leading causes of acquired and treatable blindness in adults. The main anatomical site of inflammation is the uveal tract, which is the vascular organ of the eye, but uveitis is now used to describe IOI more globally. In around 40% of the cases of uveitis an underlying systemic disease, often of autoimmune origin, can be identified. In autoimmune diseases with IOI, uveitis may be the first clinical manifestation and may represent the most severe sign. Studies in animal models, especially in experimental autoimmune uveitis (EAU), offer the opportunity to investigate the pathogenicity of these disorders. The conventional treatment of IOI includes corticosteroids and immunosuppressive agents, which are efficient in around one-half of the patients, but their effectiveness is also limited by their iatrogenicity. The effects of intravenous immunoglobulins (IVIGs) on ocular inflammation have been investigated in a wide spectrum of autoimmune/systemic diseases. Most of the publications are case series or open trials. They show favorable results in a subset of indications, including mainly ocular cicatricial pemphigoid (OCP), Vogt-Koyanagi-Harada (VKH) syndrome, or birdshot disease. Efficacy results are more debated in other conditions such as inflammatory demyelinating optic neuritis. In other diseases with IOI only case reports are available, suggesting that IVIGs may be of some interest. These observations support the need for controlled trials to demonstrate the efficacy of IVIGs and assess their potential steroid-sparing effect.

Intravenous immunoglobulins in autoimmune- or parvovirus B19-mediated pure red-cell aplasia.

Pure red-cell aplasia (PRCA) is defined as the absence of mature erythroid precursors in a bone marrow that otherwise exhibit normal cellularity. Acquired PRCA may occur in association with neoplasms (such as lymphoproliferative disorders), thymoma, autoimmune disorders, pregnancy, or as a consequence of chronic human parvovirus B19 (B19) infection in an immunologically incompetent host. PRCA may also develop after exposure to drugs (erythropoietin or tacrolimus). PRCA of autoimmune origin was first treated successfully with intravenous immunoglobulins (IVIg) more than 20 years ago. Since then, B19-associated PRCA in solid-organ transplant recipients and in human immunodeficiency virus (HIV)-infected patients has also been successfully treated with IVIg. Routine maintenance therapy is probably not indicated in HIV-infected patients with CD4+ counts above 300/microL, whereas repeated infusions might be necessary if CD4+ count is below 80.

Intravenous immunoglobulin in eye involvement.

Ocular inflammation may affect all eye layers: conjunctiva, sclera, uvea, and orbital tissues. The main eye involvement requiring a systemic treatment is uveitis, which represents a heterogeneous group of rare diseases, most of which are sight-threatening. In around 40% of uveitis cases an underlying systemic disease, often of autoimmune origin, can be identified. In autoimmune diseases with intraocular inflammation (IOI), uveitis may be the first clinical manifestation and may represent the most severe sign. Studies in animal models, especially in experimental autoimmune uveitis (EAU), offer the opportunity to investigate the pathogenicity of these disorders. The conventional treatment of IOI includes corticosteroids and immunosuppressive agents, which are efficient in around one-half of the patients; however, their effectiveness is also limited by their iatrogenicity. The effects of intravenous immunoglobulin (IVIg) on ocular inflammation have been investigated in a wide spectrum of autoimmune/systemic diseases. Most publications are case series or open trials. They show favorable results in a subset of indications including mainly ocular cicatricial pemphigoid, Vogt-Koyanagi-Harada syndrome, or birdshot disease. Efficacy results are more debated in other conditions, such as inflammatory demyelinating optic neuritis. In other diseases with IOI (Wegener disease, Behcet's disease, inflammatory myositis), only case reports are available, suggesting that IVIg may be of some interest. These observations support the need for controlled trials to demonstrate the efficacy of IVIg and assess their potential steroid-sparing effect.

Management of haemophilia A-inhibitor patients: clinical and regulatory perspectives.

Inhibitors to factor VIII (FVIII) are alloantibodies directed against epitopes able to neutralise FVIII procoagulant activity. They may render FVIII replacement therapy ineffective. They represent the most severe complication of haemophilia A. At least three mechanisms of FVIII neutralisation activity by anti-FVIII antibodies have been described: (1) steric hindrance; (2) recognition of neo-epitopes and (3) catalytic activity. The Nijmegen modification of the Bethesda is the recommended method for inhibitor surveillance. The occurrence of inhibitors is a relatively frequent and early event in previously untreated patients. Conversely, it is rare in previously treated patients. Therapeutic strategies for managing inhibitors include: inhibitor eradication, haemostatic management of bleeding episodes and/or surgery and supportive care. For high responding inhibitors, immune tolerance induction (ITI) is the strategy for achieving antigen-specific tolerance to FVIII. ITI success rate ranges commonly between 60% and 80%. For treatment of patients with high-titre, high-responding inhibitors, 'by-pass' therapy is generally recommended. Activated prothrombin complex concentrates represent the historically primary 'by-pass' treatment. Recombinant factor VIIa has also been widely used as a by-passing agent. Considering the small patient population, it has to be considered that full immunogenicity data cannot be collected premarketing authorisation. Thus, stringent follow-up of patients in the post-authorisation phase is required.

In vivo altered unfolded protein response and apoptosis in livers from lipopolysaccharide-challenged cirrhotic rats.

BACKGROUND/AIMS: Endoplasmic reticulum (ER)-related unfolded protein response (UPR) is mediated by PKR-like ER kinase (PERK), ATF6 and IRE1. PERK phosphorylates eukaryotic translation initiation factor-2alpha (eIF2alpha) to attenuate protein synthesis, including in NF-kappaB-dependent antiapoptotic proteins. We hypothesized that an altered UPR in the liver may sensitize cirrhotic livers to LPS-induced, TNFalpha-mediated apoptosis. Thus, we examined in vivo UPR and NF-kappaB activity in livers from cirrhotic and normal LPS-challenged rats. METHODS: Livers were harvested in rats that did or did not receive LPS. RESULTS: Under baseline conditions, no UPR was found in normal livers while PERK/eIF2alpha and ATF6 pathways were activated in cirrhotic livers. After LPS, in normal livers, the PERK/eIF2alpha pathway was transiently activated. ATF6 and IRE1 were activated. In cirrhotic livers, the PERK/eIF2alpha pathway remained elevated. ATF6 and IRE1 pathways were altered. LPS-induced, NF-kappaB-dependent antiapoptotic proteins increased in normal livers whereas their expression was blunted at the posttranscriptional level in cirrhotic livers. CONCLUSIONS: Cirrhotic livers exhibit partial UPR activation in the basal state and full UPR, although altered, after LPS challenge. Sustained eIF2alpha phosphorylation, a hallmark of cirrhotic liver UPR, is associated with a lack of LPS-induced accumulation of NF-kappaB-dependent antiapoptotic proteins which may sensitize cirrhotic livers to LPS/TNFalpha-mediated apoptosis.

Comparison of outcome in patients with cirrhosis and ascites following treatment with albumin or a synthetic colloid: a randomised controlled pilot trail.

BACKGROUND: The question of which colloid (albumin or synthetic colloids) used for plasma expansion following paracentesis or other complications requiring fluid loading in patients with cirrhosis remains controversial. AIMS: To compare outcome and hospital-related cost in patients with cirrhosis treated with 20% human albumin with those treated with a synthetic colloid (3.5% polygeline). METHODS: The primary end point was occurrence of a first liver-related complication. RESULTS: When the trial was prematurely discontinued because of safety concerns about bovine-derived products, 30 patients were assigned to receive albumin and 38 were assigned to receive a synthetic colloid. Sixty-three patients were included for ascites removal by paracentesis and five patients for ascites removal by paracentesis and renal impairment. The median time to first liver-related complication was not significantly longer in the albumin group (20 vs. 7 days). However, the total number of liver-related complications adjusted to a 100-day period was significantly lower in the albumin group. The median hospital cost for a 30-day period was significantly lower in the albumin group (1915 euros vs. 4612 euros). CONCLUSIONS: In patients with cirrhosis and ascites, human albumin appears to be more effective in preventing liver-related complications than synthetic colloid. This may be associated with decreased hospital costs.