Cold Vs Hot Snare Endoscopic Resection of Large Nonpedunculated Colorectal Polyps: Randomized Controlled German CHRONICLE Trial.

BACKGROUND & AIMS: Endoscopic mucosal resection (EMR) is standard therapy for nonpedunculated colorectal polyps ≥20 mm. It has been suggested recently that polyp resection without current (cold resection) may be superior to the standard technique using cutting/coagulation current (hot resection) by reducing adverse events (AEs), but evidence from a randomized trial is missing. METHODS: In this randomized controlled multicentric trial involving 19 centers, nonpedunculated colorectal polyps ≥20 mm were randomly assigned to cold or hot EMR. The primary outcome was major AE (eg, perforation or postendoscopic bleeding). Among secondary outcomes, major AE subcategories, postpolypectomy syndrome, and residual adenoma were most relevant. RESULTS: Between 2021 and 2023, there were 396 polyps in 363 patients (48.2% were female) enrolled for the intention-to-treat analysis. Major AEs occurred in 1.0% of the cold group and in 7.9% of the hot group (P = .001; odds ratio [OR], 0.12; 95% CI, 0.03-0.54). Rates for perforation and postendoscopic bleeding were significantly lower in the cold group, with 0% vs 3.9% (P = .007) and 1.0% vs 4.4% (P = .040). Postpolypectomy syndrome occurred with similar frequency (3.1% vs 4.4%; P = .490). After cold resection, residual adenoma was found more frequently, with 23.7% vs 13.8% (P = .020; OR, 1.94; 95% CI, 1.12-3.38). In multivariable analysis, lesion diameter of ≥4 cm was an independent predictor for major AEs (OR, 3.37) and residual adenoma (OR, 2.47) and for high-grade dysplasia/cancer for residual adenoma (OR, 2.92). CONCLUSIONS: Cold resection of large, nonpedunculated colorectal polyps appears to be considerably safer than hot EMR; however, at the cost of a higher residual adenoma rate. Further studies have to confirm to what extent polyp size and histology can determine an individualized approach. German Clinical Trials Registry (Deutsches Register Klinischer Studien), Number DRKS00025170.

Hepatitis D virus infection, innate immune response and antiviral treatments in stem cell-derived hepatocytes.

BACKGROUND: Human pluripotent stem cell (hPSC)-derived hepatocyte-like cells (HLCs) are a valuable model to investigate host-pathogen interactions of hepatitis viruses in a mature and authentic environment. Here, we investigate the susceptibility of HLCs to the hepatitis delta virus (HDV). METHODS: We differentiated hPSC into HLCs, and inoculated them with infectious HDV produced in Huh7NTCP . HDV infection and cellular response was monitored by RTqPCR and immunostaining. RESULTS: Cells undergoing hepatic differentiation become susceptible to HDV after acquiring expression of the viral receptor Na+ -taurocholate co-transporting polypeptide (NTCP) during hepatic specification. Inoculation of HLCs with HDV leads to detection of intracellular HDV RNA and accumulation of the HDV antigen in the cells. Upon infection, the HLCs mounted an innate immune response based on induction of the interferons IFNB and L, and upregulation of interferon-stimulated genes. The intensity of this immune response positively correlated with the level of viral replication and was dependant on both the JAK/STAT and NFκB pathway activation. Importantly, this innate immune response did not inhibit HDV replication. However, pre-treatment of the HLCs with IFNα2b reduced viral infection, suggesting that ISGs may limit early stages of infection. Myrcludex efficiently abrogated infection and blocked innate immune activation. Lonafarnib treatment of HDV mono infected HLCs on the other hand led to exacerbated viral replication and innate immune response. CONCLUSION: The HDV in vitro mono-infection model represents a new tool to study HDV replication, its host-pathogen interactions and evaluate new antiviral drugs in cells displaying mature hepatic functions.

Learning curve of endoscopic submucosal dissection (ESD) with prevalence-based indication in unsupervised Western settings: a retrospective multicenter analysis.

BACKGROUND AND AIMS: As there is still no consensus about the adequate training strategy for ESD in Western countries, we evaluated unsupervised prevalence-based learning curves including detailed organ-specific subgroup analysis. METHODS: The first 120 ESDs of four operators (n = 480) were divided into three groups (1: ESD 1-40, 2: ESD 41-80, 3: ESD 81-120). Outcome parameters were rates of technical success, en bloc and R0 resection, the resection speed, rates of conversion to EMR, curative resection, adverse events, surgery due to adverse events, and recurrence. In addition, we analyzed the achievement of quality benchmarks indicating levels of expertise. RESULTS: After exclusion of pretreated lesions, 438 procedures were enrolled in the final analysis. Technical success rates were > 96% with significant improvements regarding rate of en bloc resection (from 82.6 to 91.2%), resection speed (from 4.54 to 7.63 cm2/h), and rate of conversion to EMR (from 22.0 to 8.1%). No significant differences could be observed for rates of R0 resection (65.9 vs. 69.6%), curative resection (55.8 vs. 55.7%), adverse events (16.3 vs. 11.7%), surgery due to adverse events (1.5 vs. 1.3%), and recurrence (12.5 vs. 4.5%). Subgroup and benchmark analysis revealed an improvement in esophageal, gastric, and rectal ESD with achievement of competence levels for the esophagus and stomach within 80 and most of the benchmarks for proficiency level within 120 procedures. Some of the benchmarks could also be achieved in rectal ESD. CONCLUSIONS: This trial confirms safety and feasibility of unsupervised ESD along the initial learning curve with prevalence-based indication and exclusion of colonic cases.

Characteristics and endoscopic treatment of interventional and non-interventional iatrogenic colorectal perforations in centers with high endoscopic expertise: a retrospective multicenter study.

BACKGROUND: Iatrogenic colorectal perforation is a rare event with a relevant mortality and the need for surgical therapy in around ¾ of cases. METHODS: In this retrospective multicentric cohort study iatrogenic colorectal perforations from 2004 to 2021 were analyzed. Primary outcome parameters were incidence and clinical success of 1st line endoscopic treatment. Comparative analysis of interventional and non-interventional perforations was performed and predictors for clinical success of endoscopic therapy were identified. RESULTS: From 103,570 colonoscopies 213 (0.2%) iatrogenic perforations were identified. 68.4% were interventional (80 during polypectomy/EMR, 54 during ESD and 11 for other reasons) and 31.6% non-interventional perforations (39 by the tip, 19 by the shaft, 7 by inversion, two by biopsy and one by distension). Incidence of 1st line endoscopic therapy was 61.0% and clinical success 81.5%. Other non-surgical therapies were conducted in 8.9% with clinical success in 94.7% of cases. In interventional perforations both incidence and clinical success of 1st line endoscopic therapy were significantly higher compared to non-interventional perforations [71.7% vs. 38.2% (p < 0.01) resp. 86.5% vs. 61.5% (p < 0.01)]. Mortality was 2.3% and significantly lower in the group of interventional perforations (0.7% vs. 5.9%, p = 0.037). Multivariable analysis revealed perforation size < 5 mm as only independent predictor for clinical success of 1st line endoscopic treatment [OR 14.85 (1.57-140.69), p = 0.019]. CONCLUSIONS: Endoscopic therapy is treatment of choice in the majority of iatrogenic colorectal perforations. In case of interventional perforations it is highly effective but only a minority of non-interventional perforations are good candidates for endoscopic treatment.

Predictive Factors for the Outcome of Unsupervised Endoscopic Submucosal Dissection During the Initial Learning Curve with Prevalence-Based Indication.

BACKGROUND: For an adequate educational strategy of ESD in non-Asian settings with prevalence-based indication it is essential to define adequate lesions, suitable for the beginner without on-site expert-supervision. AIMS: We analyzed possible predictors for outcome parameters of effectiveness and safety during the initial learning curve. METHODS: The first 120 ESDs of four operators (n = 480), performed between 2007 and 2020 in four tertiary hospitals, were enrolled. Uni-/multivariable regression analysis was done with sex, age, pretreated lesion, lesion size, organ, and organ-based localization as possible independent predictors for en bloc resection (EBR), complication, and resection speed. RESULTS: Rates of EBR, complication, and resection speed were 84.5%, 14.2%, and 6.20 (± 4.45) cm2/h. Independent predictors for EBR were pretreated lesion (OR 0.27 [0.13-0.57], p < 0.001) and non-colonic ESD (OR 2.29 [1.26-4.17] (rectum)/5.72 [2.36-13.89] (stomach)/7.80 [2.60-23.42] (esophagus), p < 0.001), for complication pretreated lesion (OR 3.04 [1.46-6.34], p < 0.001) and lesion size (OR 1.02 [1.004-1.04], p = 0.012) and for resection speed pretreated lesion (RC - 3.10 [- 4.39 to - 1.81], p < 0.001), lesion size (RC 0.13 [0.11-0.16], p < 0.001) and male patient (RC - 1.11 [- 1.85 to - 0.37], p < 0.001). We found no significant difference in the incidence of technically unsuccessful resections in esophageal (1/84), gastric (3/113), rectal (7/181), and colonic (3/101) ESDs (p = 0.76). Technical failure was mainly caused by complication and fibrosis/pretreatment. CONCLUSION: During the initial learning curve of an unsupervised ESD program with prevalence-based indication, pretreated lesions and colonic ESDs should be avoided. In contrast, lesion size and organ-based localizations have less predictive value for the outcome.

Filovirus Antiviral Activity of Cationic Amphiphilic Drugs Is Associated with Lipophilicity and Ability To Induce Phospholipidosis.

Several cationic amphiphilic drugs (CADs) have been found to inhibit cell entry of filoviruses and other enveloped viruses. Structurally unrelated CADs may have antiviral activity, yet the underlying common mechanism and structure-activity relationship are incompletely understood. We aimed to understand how widespread antiviral activity is among CADs and which structural and physico-chemical properties are linked to entry inhibition. We measured inhibition of Marburg virus pseudoparticle (MARVpp) cell entry by 45 heterogeneous and mostly FDA-approved CADs and cytotoxicity in EA.hy926 cells. We analyzed correlation of antiviral activity with four chemical properties: pKa, hydrophobicity (octanol/water partitioning coefficient; ClogP), molecular weight, and distance between the basic group and hydrophobic ring structures. Additionally, we quantified drug-induced phospholipidosis (DIPL) of a CAD subset by flow cytometry. Structurally similar compounds (derivatives) and those with similar chemical properties but unrelated structures (analogues) to those of strong inhibitors were obtained by two in silico similarity search approaches and tested for antiviral activity. Overall, 11 out of 45 (24%) CADs inhibited MARVpp by 40% or more. The strongest antiviral compounds were dronedarone, triparanol, and quinacrine. Structure-activity relationship studies revealed highly significant correlations between antiviral activity, hydrophobicity (ClogP > 4), and DIPL. Moreover, pKa and intramolecular distance between hydrophobic and hydrophilic moieties correlated with antiviral activity but to a lesser extent. We also showed that in contrast to analogues, derivatives had antiviral activity similar to that of the seed compound dronedarone. Overall, one-quarter of CADs inhibit MARVpp entry in vitro, and antiviral activity of CADs mostly relies on their hydrophobicity yet is promoted by the individual structure.

Delayed onset of smooth muscle cell differentiation leads to hydroureter formation in mice with conditional loss of the zinc finger transcription factor gene Gata2 in the ureteric mesenchyme.

The establishment of the peristaltic machinery of the ureter is precisely controlled to cope with the onset of urine production in the fetal kidney. Retinoic acid (RA) has been identified as a signal that maintains the mesenchymal progenitors of the contractile smooth muscle cells (SMCs), while WNTs, SHH, and BMP4 induce their differentiation. How the activity of the underlying signalling pathways is controlled in time, space, and quantity to activate coordinately the SMC programme is poorly understood. Here, we provide evidence that the Zn-finger transcription factor GATA2 is involved in this crosstalk. In mice, Gata2 is expressed in the undifferentiated ureteric mesenchyme under control of RA signalling. Conditional deletion of Gata2 by a Tbx18cre driver results in hydroureter formation at birth, associated with a loss of differentiated SMCs. Analysis at earlier stages and in explant cultures revealed that SMC differentiation is not abrogated but delayed and that dilated ureters can partially regain peristaltic activity when relieved of urine pressure. Molecular analysis identified increased RA signalling as one factor contributing to the delay in SMC differentiation, possibly caused by reduced direct transcriptional activation of Cyp26a1, which encodes an RA-degrading enzyme. Our study identified GATA2 as a feedback inhibitor of RA signalling important for precise onset of ureteric SMC differentiation, and suggests that in a subset of cases of human congenital ureter dilatations, temporary relief of urine pressure may ameliorate the differentiation status of the SMC coat. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Chronic hepatitis delta virus infection leads to functional impairment and severe loss of MAIT cells.

BACKGROUND & AIMS: Hepatitis delta virus (HDV) infection is the most severe form of viral hepatitis. Although HDV-associated liver disease is considered immune-mediated, adaptive immune responses against HDV are weak. Thus, the role of several other cell-mediated mechanisms such as those driven by mucosa-associated invariant T (MAIT) cells, a group of innate-like T cells highly enriched in the human liver, has not been extensively studied in clinical HDV infection. METHODS: MAIT cells from a sizeable cohort of patients with chronic HDV were analyzed ex vivo and in vitro after stimulation. Results were compared with MAIT cells from hepatitis B virus (HBV) monoinfected patients and healthy controls. RESULTS: Circulating MAIT cells were dramatically decreased in the peripheral blood of HDV-infected patients. Signs of decline were also observed in the liver. In contrast, only a modest decrease of circulating MAIT cells was noted in HBV monoinfection. Unsupervised high-dimensional analysis of residual circulating MAIT cells in chronic HDV infection revealed the appearance of a compound phenotype of CD38hiPD-1hiCD28loCD127loPLZFloEomesloHelioslo cells indicative of activation. Corroborating these results, MAIT cells exhibited a functionally impaired responsiveness. In parallel to MAIT cell loss, HDV-infected patients exhibited signs of monocyte activation and increased levels of proinflammatory cytokines IL-12 and IL-18. In vitro, IL-12 and IL-18 induced an activated MAIT cell phenotype similar to the one observed ex vivo in HDV-infected patients. These cytokines also promoted MAIT cell death, suggesting that they may contribute to MAIT cell activation and subsequent loss during HDV infection. CONCLUSIONS: These results suggest that chronic HDV infection engages the MAIT cell compartment causing activation, functional impairment, and subsequent progressive loss of MAIT cells as the HDV-associated liver disease progresses. LAY SUMMARY: Hepatitis delta virus (HDV) infection is the most severe form of viral hepatitis. We found that in patients with HDV, a subset of innate-like T cells called mucosa-associated invariant T cells (or MAIT cells), which are normally abundant in peripheral blood and the liver, are activated, functionally impaired and severely depleted.

SEC14L2, a lipid-binding protein, regulates HCV replication in culture with inter- and intra-genotype variations.

BACKGROUND & AIMS: The lipid-binding protein, SEC14L2, is crucial for the efficient viral replication of clinical hepatitis C virus (HCV) isolates in cell culture. Given the role of SEC14L2 in HCV replication, we aimed to study a large number of HCV positive sera carrying genotypes 1-4, to identify viral factors associated with efficient replication in culture. Additionally, we investigated whether 13 single nucleotide polymorphisms (SNPs) of SEC14L2 have an impact on RNA replication of naturally occurring HCV isolates. METHODS: We generated Huh-7.5 cell lines overexpressing SEC14L2 or 13 coding SNPs and tested 73 different HCV positive sera for in vitro replication. Furthermore, we genotyped a cohort of 262 patients with chronic HCV for the common SNP (rs757660) and investigated its effect on the clinical phenotype. RESULTS: HCV isolates from genotype 1, 2, 3 and 4 replicate in Huh-7.5 cells overexpressing SEC14L2. Interestingly, only subgenomic replicons from genotypes 1 and 3 showed enhanced replication whereas genotypes 2 and 4 remained unaffected. Furthermore, replication was independent of viral load. Importantly, all tested SNPs supported HCV RNA replication in vitro, while 1 SNP was associated with decreased SEC1L2 expression and viral RNA. All SNPs exhibited comparable cellular cholesterol and vitamin E abundance in naïve Huh-7.5 cells. CONCLUSIONS: This large screen of natural HCV isolates of 4 genotypes underscores the relevance of SEC14L2 as an in vitro HCV host factor. Additionally, SEC14L2 variants appear to recapitulate the wild-type enhancement of HCV replication. Variant rs191341134 showed a decreased effect due to lowered stability, whereas variant rs757660, a high prevalence mutant, showed a similar phenotype to the wild-type. LAY SUMMARY: Until the year 2015, consistent replication of patient-derived isolates of hepatitis C virus (HCV) in an in vitro model remained a limitation in HCV research. In 2015 a group of authors identified a protein named SEC14L2 that enabled the replication of HCV isolates in cell culture. We performed a large screen encompassing 73 isolates of 4 different HCV genotypes. Additionally, we replaced the natural SEC14L2 with 13 different mutants to test if the protein variation significantly altered its HCV replication enhancing functions. We showed that different genotypes of HCV react differently to the presence of this protein and the variants of the protein mimic the behavior of the wild-type.

Patterns of Resistance-Associated Substitutions in Patients With Chronic HCV Infection Following Treatment With Direct-Acting Antivirals.

BACKGROUND & AIMS: Little is known about substitutions that mediate resistance of hepatitis C virus (HCV) to direct-acting antivirals (DAAs), due to the small number of patients with treatment failure in approval studies. It is important to identify resistance patterns to select effective salvage treatments. METHODS: We performed a comprehensive analysis for resistance-associated substitutions (RASs) in HCV genes (nonstructural protein [NS]3, NS5A, NS5B) targeted by DAAs. We compared NS3, NS5A, and NS5B sequences from 626 patients in Europe with DAA failure with sequences from 2322 DAA-naïve patients, infected with HCV genotypes 1 to 4. We considered RASs to be relevant if they were associated with DAA failure in patients or conferred a greater than twofold change in susceptibility compared with a reference strain in in vitro replicon assays. Data were collected on pretreatment status, DAA regimen, the treatment initiation date and duration, and virologic response. Patients who received at least 4 weeks of antiviral treatment were included in the analysis. RESULTS: RASs in NS3 associated with simeprevir or paritaprevir failure include R155K and D168E/V. In addition, several RASs were specifically associated with failure of simeprevir (Q80K/R in patients with genotype 1a or 4) or paritaprevir (Y56H in combination with D168V in patients with genotype 1b). Y93H in NS5A was the RAS most frequently associated with failure of daclatasvir, ledipasvir, or ombitasvir in patients with genotype 1b infection, and L31M was associated with failure of daclatasvir or ledipasvir, but not ombitasvir. RASs in NS5A were heterogeneous among patients with HCV genotype 1a or genotype 4 infections. In patients with HCV genotype 3, Y93H was associated with resistance to daclatasvir, but no RASs were associated with ledipasvir failure, pointing to a limited efficacy of ledipasvir in patients with genotype 3. Among patients failed by sofosbuvir-containing regimens, L159F was enriched in patients with genotype 1b (together with C316N) or genotype 3 infection, whereas the RAS S282T was rarely observed. CONCLUSIONS: We compared RASs in NS3, NS5A, and NS5B among patients failed by DAA therapy. Theses varied with the HCV genotype and subtype, and the different drug classes. These findings might be used to select salvage therapies.

Endoscopic biliary drainage in patients with cholangiocarcinoma - self-expanding metal versus polyethylene stents.

Background: Endoscopic biliary drainage is the standard of care for patients with cholangiocarcinoma (CCA)-induced, obstructive jaundice. Self-expanding metal stents are supposed to be superior to polyethylene stents in terms of reduction of interventions and costs. So far, there are only few real-life data with respect to stent selection and survival in this patient cohort. Methods: In this study, we retrospectively analyzed patients with CCA treated with endoscopic biliary drainage from 2000 to 2015 at Hannover Medical School, Germany. The aim of this study was to analyze whether metal stenting reduces the frequency of interventions and influences survival in a large, real-life cohort. Results: Overall, 422 patients with CCA were included in this study. Indication for endoscopic biliary drainage was most often obstructive jaundice (n = 397; 94.1%). Among these patients, 20 patients (5%) were initially treated with a metal stent and 38 (9.6%) received a metal stent in the subsequent course. Median number of interventions per month was 2.4-fold reduced following metal stenting. Patients first treated with a metal stent had a more advanced tumor stage and a significantly shorter median overall survival (mOS) compared to patients who received a metal stent subsequently (7.5 months vs. 15.2 months; p=.019). There was no difference in mOS for metal vs. polyethylene stenting following a propensity score match for the confounders curative resection and chemotherapy (13.2 vs. 13.7 months, p=.555). Conclusions: Our data confirm that metal stenting reduces the frequency of interventions, but does not influence OS. Metal stenting should be considered specifically in younger patients who are suitable for chemotherapy.

[Diseases and diagnosis of the biliary system : When does the gastroenterologist need the radiologist?] / Erkrankungen und Diagnostik der Gallenwege : Wann braucht der Gastroenterologe den Radiologen?

CLINICAL ISSUE: Biliary diseases require fast and rational use of diagnostic tests by both gastroenterologists and radiologists. STANDARD TREATMENT: Standard diagnostic workup includes transabdominal ultrasound, endoscopic retrograde cholangiography (ERC), endoscopic ultrasound, direct cholangioscopy, magnetic resonance cholangiopancreatography (MRI/MRCP), and computed tomography (CT). TREATMENT INNOVATIONS: Modular cholangioscopy is a novel diagnostic method. DIAGNOSTIC WORK-UP: The goal of diagnostic examinations is the determination of the location of obstructions and differentiation of benign from malignant lesions. ACHIEVEMENTS: Transabdominal ultrasound is risk-free and can show the gallbladder in great detail providing high diagnostic accuracy in most conditions. Endoscopic ultrasound, ERC and/or cholangioscopy are powerful tools to investigate the large bile ducts but are associated with inherent procedural risks. PRACTICAL RECOMMENDATIONS: Gall bladder diseases can often be diagnosed with transabdominal ultrasound alone. Bile duct disease often requires the use of endoscopic ultrasound, ERC and/or cholangioscopy.

Transjugular diagnostics in acute liver failure including measurements of hepatocentral venous biomarker gradients.

AIM: Acute liver failure (ALF) is a syndrome of severe liver injury that may need urgent liver transplantation and is associated with significant risk of death. Early outcome prediction and further possibilities to increase accuracy of prognosis scores are important. METHODS: We examined 30 patients with ALF, according to the novel criteria of the Intractable Hepato-Biliary Diseases Study Group, who underwent transjugular liver biopsy (TJLB) and investigated the relevance of histology for correct diagnosis and etiology. We assessed the suitability of necrosis (%), hepatic venous pressure gradients (HVPG), and hepatocentral venous gradients of serum biomarkers for outcome prediction. For this purpose, we calculated the difference of biomarker levels between hepatic vein (HV) and superior vena cava (SVC) blood samples. RESULTS: Histology of TJLB specimens contributed to finding the etiology in 83%. Necrosis (%) and HVPGs were not significantly different between outcome groups. In gradient measurements, caspase 3/7 activity and total cytokeratin 18 (CK-18) (M65) had significant and relevant levels different from zero. Although they were not accurate for outcome prediction, differences between outcome groups were detected in caspase activation: levels of caspase 3/7 activity in the HV and caspase-cleaved CK-18 (M30) in the SVC were significantly higher in spontaneously recovered patients. CONCLUSIONS: Our results underline the role of caspase activation in spontaneous recovery from ALF. Furthermore, the calculation of hepatocentral venous biomarker gradients could represent a new diagnostic tool whose clinical potential needs to be further investigated.

Scavenger receptor class B member 1 (SCARB1) variants modulate hepatitis C virus replication cycle and viral load.

BACKGROUND & AIMS: There are numerous coding and non-coding variants in the SCARB1 gene that encodes scavenger receptor class B member 1 (SR-BI), a key receptor for both high density lipoproteins and hepatitis C virus (HCV). Many have been linked to clinical phenotypes, yet their impact on the HCV replication cycle is incompletely understood. The aim of this study was to analyze the impact of these variants on the molecular biology and clinical course of HCV. METHODS: We analyzed key coding non-synonymous as well as non-coding SCARB1 variants using virological in vitro and human genetics approaches. RESULTS: Non-synonymous variants: S112F and T175A have greatly reduced HCV receptor function. When present on the cell surface, these variants are impaired in their ability to interact with HCV E2. Non-coding variants: The G allele in rs3782287 is associated with decreased viral load. Haplotype analysis confirmed these findings and identified haplotype rs3782287 A/rs5888 C as a risk allele associated with increased viral load. We also detected a trend towards lower hepatic SR-BI expression in individuals with the rs3782287 GG genotype associated with low viral load suggesting a potential underlying mechanism. CONCLUSION: Coding and non-coding genetic SCARB1 variants modulate the HCV replication cycle and possibly clinical features of hepatitis C. These findings underscore the relevance of SR-BI as an HCV receptor and contribute to our understanding of inter-individual variation in HCV infection. LAY SUMMARY: The cell surface receptor SR-BI (scavenger receptor class B member 1), is essential for hepatitis C virus (HCV) entry into hepatocytes. Variations in the gene coding this receptor influence infectivity and viral load. We analyzed these variations to gain a better understanding of inter-individual differences over the course of HCV infection.

Prevention strategies for blood-borne viruses-in the Era of vaccines, direct acting antivirals and antiretroviral therapy.

Blood-borne viruses, such as hepatitis B virus, hepatitis C virus, human immunodeficiency virus, and the facultative blood-borne hepatitis E virus, are considered a major public health problem given that they are accountable for millions of deaths each year. Treatment options, including effective vaccine design, development of antiviral strategies and the implementation of antiretroviral therapy have improved substantially over the last couple of years and contribute to successful treatment and prevention of these infectious diseases. In this review, we summarise the current knowledge and concepts in prevention of transmission of these blood-borne viruses.

Modulation of HCV reinfection after orthotopic liver transplantation by fibroblast growth factor-2 and other non-interferon mediators.

OBJECTIVE: In HCV infected individuals graft infection occurs shortly after orthotopic liver transplantation (OLT). We aimed to describe the composition of the inflammatory response at this time, how it affects the HCV replication cycle and identify novel proviral and antiviral factors. DESIGN: We used a Luminex assay to quantify 50 inflammatory mediators in sera before and shortly after OLT. In vitro grown HCV based on the JFH-1 isolate were used to characterise the effects of patient sera and individual mediators on HCV. RESULTS: Although the mediator composition is highly variable between individuals, sera drawn immediately post-OLT significantly enhance HCV infectivity compared with control sera from before OLT in about half of the cases. Among 27 non-interferon inflammatory mediators fibroblast growth factor (FGF)-2 stood out as it enhanced HCV RNA replication and release of infectious particles. The effect was concentration-dependent and detectable in dividing and non-dividing cells. Moreover, pharmacological inhibition of FGF-2 receptor signalling abrogated the enhancing effect of FGF-2 and inhibited HCV replication in the absence of serum FGF-2 suggesting that HCV replication is dependent on basal activation of the FGF-2 triggered signalling pathway. Finally, in individuals with chronic HCV infection with high viral load, serum FGF-2 was significantly higher compared with those with low viral load. CONCLUSIONS: Although no single mediator may account for this effect, serum shortly post-OLT enhances HCV infection. FGF-2 is a novel endogenous driver of HCV replication and a potential therapeutic target.

Host cell mTORC1 is required for HCV RNA replication.

OBJECTIVE: Chronically HCV-infected orthotopic liver transplantation (OLT) recipients appear to have improved outcomes when their immunosuppressive regimen includes a mammalian target of rapamycin (mTOR) inhibitor. The mechanism underlying this observation is unknown. DESIGN: We used virological assays to investigate mTOR signalling on the HCV replication cycle. Furthermore, we analysed HCV RNA levels of 42 HCV-positive transplanted patients treated with an mTOR inhibitor as part of their immunosuppressive regimen. RESULTS: The mTOR inhibitor rapamycin was found to be a potent inhibitor for HCV RNA replication in Huh-7.5 cells as well as primary human hepatocytes. Half-maximal inhibition was observed at 0.01 µg/mL, a concentration that is in the range of serum levels seen in transplant recipients and does not affect cell proliferation. Early replication cycle steps such as cell entry and RNA translation were not affected. Knockdown of raptor, an essential component of mTORC1, but not rictor, an essential component of mTORC2, inhibited viral RNA replication. In addition, overexpression of raptor led to higher viral RNA replication, demonstrating that mTORC1, but not mTORC2, is required for HCV RNA replication. In 42 HCV-infected liver-transplanted or kidney-transplanted patients who were switched to an mTOR inhibitor, we could verify that mTOR inhibition decreased HCV RNA levels in vivo. CONCLUSIONS: Our data identify mTORC1 as a novel HCV replication factor. These findings suggest an underlying mechanism for the observed benefits of mTOR inhibition in HCV-positive OLT recipients and potentiate further investigation of mTOR-containing regimens in HCV-positive recipients of solid organ transplants.

The clinically approved drugs amiodarone, dronedarone and verapamil inhibit filovirus cell entry.

OBJECTIVES: Filoviruses such as Ebola virus and Marburg virus cause a severe haemorrhagic fever syndrome in humans for which there is no specific treatment. Since filoviruses use a complex route of cell entry that depends on numerous cellular factors, we hypothesized that there may be drugs already approved for human use for other indications that interfere with signal transduction or other cellular processes required for their entry and hence have anti-filoviral properties. METHODS: We used authentic filoviruses and lentiviral particles pseudotyped with filoviral glycoproteins to identify and characterize such compounds. RESULTS: We discovered that amiodarone, a multi-ion channel inhibitor and adrenoceptor antagonist, is a potent inhibitor of filovirus cell entry at concentrations that are routinely reached in human serum during anti-arrhythmic therapy. A similar effect was observed with the amiodarone-related agent dronedarone and the L-type calcium channel blocker verapamil. Inhibition by amiodarone was concentration dependent and similarly affected pseudoviruses as well as authentic filoviruses. Inhibition of filovirus entry was observed with most but not all cell types tested and was accentuated by the pre-treatment of cells, indicating a host cell-directed mechanism of action. The New World arenavirus Guanarito was also inhibited by amiodarone while the Old World arenavirus Lassa and members of the Rhabdoviridae (vesicular stomatitis virus) and Bunyaviridae (Hantaan) families were largely resistant. CONCLUSIONS: The ion channel blockers amiodarone, dronedarone and verapamil inhibit filoviral cell entry.

Different requirements for scavenger receptor class B type I in hepatitis C virus cell-free versus cell-to-cell transmission.

Hepatitis C virus (HCV) is believed to initially infect the liver through the basolateral side of hepatocytes, where it engages attachment factors and the coreceptors CD81 and scavenger receptor class B type I (SR-BI). Active transport toward the apical side brings the virus in close proximity of additional entry factors, the tight junction molecules claudin-1 and occludin. HCV is also thought to propagate via cell-to-cell spread, which allows highly efficient virion delivery to neighboring cells. In this study, we compared an adapted HCV genome, clone 2, characterized by superior cell-to cell spread, to its parental genome, J6/JFH-1, with the goal of elucidating the molecular mechanisms of HCV cell-to-cell transmission. We show that CD81 levels on the donor cells influence the efficiency of cell-to-cell spread and CD81 transfer between neighboring cells correlates with the capacity of target cells to become infected. Spread of J6/JFH-1 was blocked by anti-SR-BI antibody or in cells knocked down for SR-BI, suggesting a direct role for this receptor in HCV cell-to-cell transmission. In contrast, clone 2 displayed a significantly reduced dependence on SR-BI for lateral spread. Mutations in E1 and E2 responsible for the enhanced cell-to-cell spread phenotype of clone 2 rendered cell-free virus more susceptible to antibody-mediated neutralization. Our results indicate that although HCV can lose SR-BI dependence for cell-to-cell spread, vulnerability to neutralizing antibodies may limit this evolutionary option in vivo. Combination therapies targeting both the HCV glycoproteins and SR-BI may therefore hold promise for effective control of HCV dissemination.

The spike protein of the emerging betacoronavirus EMC uses a novel coronavirus receptor for entry, can be activated by TMPRSS2, and is targeted by neutralizing antibodies.

The novel human coronavirus EMC (hCoV-EMC), which recently emerged in Saudi Arabia, is highly pathogenic and could pose a significant threat to public health. The elucidation of hCoV-EMC interactions with host cells is critical to our understanding of the pathogenesis of this virus and to the identification of targets for antiviral intervention. Here we investigated the viral and cellular determinants governing hCoV-EMC entry into host cells. We found that the spike protein of hCoV-EMC (EMC-S) is incorporated into lentiviral particles and mediates transduction of human cell lines derived from different organs, including the lungs, kidneys, and colon, as well as primary human macrophages. Expression of the known coronavirus receptors ACE2, CD13, and CEACAM1 did not facilitate EMC-S-driven transduction, suggesting that hCoV-EMC uses a novel receptor for entry. Directed protease expression and inhibition analyses revealed that TMPRSS2 and endosomal cathepsins activate EMC-S for virus-cell fusion and constitute potential targets for antiviral intervention. Finally, EMC-S-driven transduction was abrogated by serum from an hCoV-EMC-infected patient, indicating that EMC-S-specific neutralizing antibodies can be generated in patients. Collectively, our results indicate that hCoV-EMC uses a novel receptor for protease-activated entry into human cells and might be capable of extrapulmonary spread. In addition, they define TMPRSS2 and cathepsins B and L as potential targets for intervention and suggest that neutralizing antibodies contribute to the control of hCoV-EMC infection.