Vessel-Guided Mesohepatectomy for Liver Partition and Staged Major Parenchyma-Sparing Hepatectomies with Super-Selective Portal Vein Embolization or Enhanced ALPPS to Achieve R0 Resection for Colorectal Liver Metastases at the Hepatocaval Confluence.

Background. R0 minor parenchyma-sparing hepatectomy (PSH) is feasible for colorectal liver metastases (CRLM) in contact with hepatic veins (HV) at hepatocaval confluence since HV can be reconstructed, but in the case of contact with the first-order glissonean pedicle (GP), major hepatectomy is mandatory. To pursue an R0 parenchyma-sparing policy, we proposed vessel-guided mesohepatectomy for liver partition (MLP) and eventually combination with liver augmentation techniques for staged major PSH. Methods. We analyzed 15 consecutive vessel-guided MLPs for CRLM at the hepatocaval confluence. Patients had a median of 11 (range: 0-67) lesions with a median diameter of 3.5 cm (range: 0.0-8.0), bilateral in 73% of cases. Results. Grade IIIb or more complications occurred in 13%, median hospital stay was 14 (range: 6-62) days, 90-day mortality was 0%. After a median follow-up of 17.5 months, 1-year OS and RFS were 92% and 62%. In nine (64%) patients, MLP was combined with portal vein embolization (PVE) or ALPPS to perform staged R0 major PSH. Future liver remnant (FLR) volume increased from a median of 15% (range: 7-20%) up to 41% (range: 37-69%). Super-selective PVE was performed in three (33%) patients and enhanced ALPPS (e-ALPPS) in six (66%). In two e-ALPPS an intermediate stage of deportalized liver PSH was necessary to achieve adequate FLR volume. Conclusions. Vessel-guided MLP may transform the liver in a paired organ. In selected cases of multiple bilobar CRLM, to guarantee oncological radicality (R0), major PSH is feasible combining advanced surgical parenchyma sparing with liver augmentation techniques when FLR volume is insufficient.

Exploring the Outcome of Disappearance or Small Remnants of Colorectal Liver Metastases during First-Line Chemotherapy on Hepatobiliary Contrast-Enhanced and Diffusion-Weighted MR Imaging.

We aimed to evaluate the outcome of the disappearance or small remnants of colorectal liver metastases during first-line chemotherapy assessed by hepatobiliary contrast-enhanced and diffusion-weighted MR imaging (DW-MRI). Consecutive patients with at least one disappearing liver metastasis (DLM) or small residual liver metastases (≤10 mm) assessed by hepatobiliary contrast-enhanced and DW-MRI during first-line chemotherapy were included. Liver lesions were categorized into three groups: DLM; residual tiny liver metastases (RTLM) when ≤5 mm; small residual liver metastases (SRLM) when >5mm and ≤10 mm. The outcome of resected liver metastases was assessed in terms of pathological response, whereas lesions left in situ were evaluated in terms of local relapse or progression. Fifty-two outpatients with 265 liver lesions were radiologically reviewed; 185 metastases fulfilled the inclusion criteria: 40 DLM, 82 RTLM and 60 SRLM. We observed a pCR rate of 75% (3/4) in resected DLM and 33% (12/36) of local relapse for DLM left in situ. We observed a risk of relapse of 29% and 57% for RTLM and SRLM left in situ, respectively, and a pCR rate of about 40% overall for resected lesions. DLM assessed via hepatobiliary contrast-enhanced and DW-MRI very probably indicates a complete response. The surgical removal of small remnants of liver metastases should always be advocated whenever technically possible.

Impact of baseline gadoxetic acid-enhanced liver magnetic resonance and diffusion-weighted imaging in resectable colorectal liver metastases: A prospective, monocentric study.

BACKGROUND: Liver magnetic resonance imaging (MRI) utilizing hepatocyte-specific contrast agent and diffusion-weighted imaging (DWI) is currently used to properly stage colorectal liver metastases (CRLM) in patients candidate to liver surgery. However, the added value of liver MRI in choosing the treatment strategy in resectable CRLM over computed tomography (CT)-scan is not clear. PATIENTS AND METHODS: This is a prospective monocentric collection of consecutive cases of patients with CRLM conceived with the aim to assess the added value of liver MRI in changing the initial treatment strategy planned according to CT-scan. Potential changes in the initially planned strategy were defined as: - from upfront surgery to perioperative chemotherapy (fluoropyrimidine and oxaliplatin) - from upfront surgery to first-line systemic therapy (doublet or triplet plus a biological agent) - from perioperative chemotherapy to first-line systemic therapy. Hypothesising that MRI may induce a change in the choice of the treatment strategy in the 20% of cases (alternative hypothesis), against a null hypothesis of 5%, with one-tailed alpha and beta errors of 0.05 and 0.20 respectively, 27 patients were needed. The added value of liver MRI would have been considered clinically meaningful if at least 4 changes in the treatment strategy were observed. RESULTS: Among 27 enrolled patients, upfront surgery and perioperative chemotherapy strategies were chosen in 17 (63%) and 10 (37%) cases, respectively, based on CT-scan. After liver MRI, additional liver lesions were found in 8 patients (30%) and the initial strategy was changed in 7 patients (26%) (4 initially deemed candidate to upfront surgery and 3 initially sent to perioperative chemotherapy) that were treated with first-line systemic therapy. CONCLUSIONS: Our results support the indication of the current guidelines on the routine use of liver MRI in the initial workup of patients with resectable CRLM with an MRI-driven changes of initial treatment plan in a relevant percentage of cases.

Management and Treatment of Patients with Chronic Hepatitis B: Towards Personalized Medicine.

The currently available antiviral treatments (Peg-Interferon-α and Nucleos(t)ide Analogues, NA) for chronic hepatitis B (CHB) achieve a functional cure (serum HBsAg and HDV-DNA clearance) of HBV infection in a limited number of patients. Nevertheless, the continuous pharmacological suppression of viral replication by NA halts liver disease progression lowering the risk of HCC development and improving the survival. In the near future, to fully exploit the potential of old and new drugs for HBV treatment a personalized approach to the patients will be required according to an accurate definition of their virologic, immunologic and clinical profile.

Upper transversal hepatectomy with double hepatic vein resection and reconstruction to treat colorectal cancer liver metastases at the hepatocaval confluence: a strategy to achieve R0 liver-sparing resection.

BACKGROUND: Repeated hepatectomies in the therapeutic route of patients with colorectal liver metastases (CRLM) may improve their long term survival. Hepatic vein (HV) resection and reconstruction allows parenchyma-sparing hepatectomy (PSH) and R0 resections for CRLM in contact with one HV. We aimed at verifying the feasibility of PSH with double HV resection and direct reconstruction for CRLM in contact with two HVs at the hepatocaval confluence. METHODS: Out of 106 consecutive PSH performed for CRLM deep-located in segments I-IVa-VII-VIII, four (3.7%) PSH were performed with resection of CRLM en bloc with two adjacent HVs which were both reconstructed with double direct HV anastomosis: 3 cases between right-HV and middle-HV and 1 case between middle-HV and left-HV. Two patients had previously undergone liver resection. Three patients had one single lesion and one had 5 CRLMs. RESULTS: Median size of CRLMs in contact with HVs was 25 mm (range 22-30 mm). At histological examination, all resections were R0 except one R1-vascular (detachment from glissonean pedicle): in all cases at least one HV and in 1 case both HVs were infiltrated by the tumor cells. After median follow-up of 18 (range 3.5-41.2) months, all HVs were patent. All patients were alive and in good general conditions, and 3 patients were disease free (one of them following a liver re-resection). One patient experienced a grade IIIa complication. Median hospital-stay was 11 (range 9-13) days. CONCLUSION: In patients with CRLMs involving two adjacent HVs at the hepatocaval confluence, liver resection with double HV resection and direct reconstruction is feasible and may be considered to guarantee oncological radicality (R0) and spare health parenchyma.

Modeling Hepatocellular Carcinoma Cells Dynamics by Serological and Imaging Biomarkers to Explain the Different Responses to Sorafenib and Regorafenib.

In advanced HCC, tyrosine-kinase inhibitors obtain partial responses (PR) in some patients and complete responses (CR) in a few. Better understanding of the mechanism of response could be achieved by the radiomic approach combining digital imaging and serological biomarkers (α-fetoprotein, AFP and protein induced by vitamin K absence-II, PIVKA-II) kinetics. A physic-mathematical model was developed to investigate cancer cells and vasculature dynamics in three prototype patients receiving sorafenib and/or regorafenib and applied in seven others for validation. Overall four patients showed CR, two PR, two stable-disease (SD) and two progressive-disease (PD). The rate constant of cancer cells production was higher in PD than in PR-SD and CR (median: 0.398 vs. 0.325 vs. 0.316 C × day-1). Therapy induced reduction of neo-angiogenesis was greater in CR than in PR-SD and PD (median: 83.2% vs. 29.4% and 2.0%), as the reduction of cell-proliferation (55.2% vs. 7.6% and 0.7%). An additional dose-dependent acceleration of tumor vasculature decay was also observed in CR. AFP and cancer cells followed the same kinetics, whereas PIVKA-II time/dose dependent fluctuations were influenced also by tissue ischemia. In conclusion, pending confirmation in a larger HCC cohort, modeling serological and imaging biomarkers could be a new tool for systemic therapy personalization.

MR imaging features of multiple biliary hamartomas (Von Meyenburg Complex): A pictorial review and differential diagnosis.

Biliary hamartomas (BHs) are rare malformative cystic/cystic-like lesions of the liver affecting the biliary tree, named after Hanns von Meyenburg who described them for the first time and still known with this eponym to this day. They usually lack clinical symptoms, and abnormalities in liver function tests are unusual; thus, it is typically an incidental finding of liver imaging. Despite being benign lesions, BHs can pose clinical challenges; the first one is differential diagnosis with other more relevant pathological conditions. Therefore, knowledge of MR imaging findings of BHs is helpful for a prompt and correct diagnosis, avoiding unnecessary invasive procedures and/or an excessive number of radiological investigations. This pictorial review is aimed to depict the most typical MR imaging features of multiple biliary hamartomas (von Meyenburg Complex), in order to familiarize the diagnosis and facilitate the differentiation from other hepato-biliary cystic diseases.

Epidemiological, demographic and clinical data on chronic viral hepatitis C in Tuscany.

BACKGROUND: Recent introduction of direct antiviral agents (DAAs) has completely changed the scenario regarding hepatitis C virus (HCV) treatment. Certain countries' economic health programs prioritize DAAs according to specific clinical features of HCV-infected patients. The aim of this study was to define epidemiological, demographic and clinical characteristics of HCV-infected patients in the Tuscany region of central Italy. METHODS: We enrolled HCV patients with chronic viral hepatitis who were referred to the outpatient services of 16 hospitals in Tuscany from 1 January 2015 to 31 December 2015. Case report forms contained patient information including main demographic data, blood chemistry data, viral hepatitis markers, instrumental evaluations (liver biopsy or transient elastometry, liver ultrasound), eligibility for DAAs, and liver transplantation or therapy already in progress. RESULTS: Of all patients considered, 2919 HCV patients were enrolled (mean age: 57.44 ± 15.15; 54% males, 46% females). All routes of transmission were well represented (intravenous drug use in 20.7%; nosocomial/dental care in 20.6%; and coagulation factors/blood transfusions in 13.3%). Diabetes was the highest represented comorbidity (20.8%), followed by metabolic syndrome (15.5%) and ischemic heart disease (6.2%). The most prevalent HCV genotypes were 1b (47.4%) and 2 (16.5%). In the whole cohort of patients, 32.8% were cirrhotic (40 patients were listed for liver transplantation). Signs of portal hypertension were present mostly in the group older than 45 years (92.3%). Extrahepatic HCV-related diseases were present in 13.3% of cases (cryoglobulinemic syndrome in 58.3% and B-cell non-Hodgkin's lymphoma in 10.5%). CONCLUSIONS: Our study provides evidence of a high prevalence of epidemiological changes in HCV infection with a major prevalence of advanced liver disease, such as portal hypertension, in this elderly cohort of patients.

Real life experiences in HCV management in 2018.

INTRODUCTION: Hepatitis C virus (HCV) infection is a major cause of chronic liver disease, with approximately 71 million chronically infected individuals worldwide. Treatment of chronic hepatitis C has considerably improved in the last few years thanks to the introduction of direct-acting antivirals able to achieve sustained virological response in more than 95% of patients. Successful anti-HCV treatment can halt liver disease progression and solve the HCV-related extra-hepatic manifestations, eventually reducing liver-related and overall mortality. Areas covered: With the aim to respond to unmet needs in patient's identification, universal access to antiviral therapy and treatment optimization in specific setting of HCV-infected patients, a group of Italian experts met in Stresa in May 2018. The summary of the considerations arising from this meeting and the final statements are reported in this paper. Expert commentary: All the advances on HCV cure may have a real clinical impact not only in individual patients but also at the social health level if they are applied to all infected patients, independently from the stage of liver disease. Further improvements are needed in order to attain HCV elimination, such as the development of an enhanced screening program working in parallel to the present treatment options.

Techniques of parenchyma-sparing hepatectomy for the treatment of tumors involving the hepatocaval confluence: A reliable way to assure an adequate future liver remnant volume.

BACKGROUND: Parenchyma-sparing hepatectomy techniques allow a lesser volume resection (<3 adjacent segments) for tumors involving the hepatic veins at the hepatocaval confluence, assuring adequate volume of the future liver remnant. We report the ability to perform parenchyma-sparing hepatectomy as planned from the preoperative imaging and the type of vascular intervention used to preserve hepatic outflow. METHODS: We analyzed 60 consecutive parenchyma-sparing hepatectomies in 54 patients for 7 primary and 53 metastatic tumors (48 colorectal), located in segments I, VII, VIII, or IVa and involving the hepatocaval confluence. Patients had a median of 2 (range: 1-18) lesions with median diameter of 4 cm (range: 1.2-16.5), which were bilateral in 43%. RESULTS: A parenchyma-sparing hepatectomy was performed in all of the 60 cases, only one case required the resection of 3 adjacent segments. In 16 (27%) hepatic veins-resections, the outflow was assured by preservation of the inferior-right-hepatic veins in 3 (5%), of the communicating-veins in 4 (7%), of the middle-hepatic veins in 3 (4%; middle-hepatic veins patch-reconstruction in 2 cases), by polytetrafluoroethylene-grafts in 4 (7%), and by hepatic veins-anastomosis in 2 (3%). In 15 (25%) cases, the hepatic veins were resected tangentially and reconstructed by direct suture venorraphy. In 29 (48%) cases, the hepatic veins were skeletonized from the tumor. Grade IIIb to IV complications occurred in 7%, median hospital-stay was 9 days, and 90-day mortality occurred in one cirrhotic patient. Median overall and disease-free survivals were 72 and 16 months (median follow-up: 34 months). CONCLUSION: A lesser volume parenchyma-sparing hepatectomy rather than a formal major hepatectomy for tumors involving the hepatocaval confluence can be performed with a low rate of major complications (7%). Parenchyma-sparing hepatectomy should be considered in highly selected patients when evaluating liver resection for tumors involving the hepatocaval confluence based on appropriate and accurate preoperative imaging.

PTFE Graft as a "Bridge" to Communicating Veins Maturation in the Treatment of an Intrahepatic Cholangiocarcinoma Involving the 3 Hepatic Veins. The Minor-but-Complex Liver Resection.

BACKGROUND: Parenchyma-sparing liver surgery allows resecting hepatic veins (HV) at the hepatocaval confluence with minor (<3 adjacent segments) liver resections. PTFE graft can be used as a bridge to communicating-veins maturation to ensure the correct outflow of the spared liver. We present a video of an intrahepatic cholangiocarcinoma (IC) involving the three HV at the hepatocaval confluence treated with this approach. METHODS: In a 50-year old obese (BMI 44.8) male a 6-cm IC involving the hepatocaval confluence was identified during the follow-up for a kidney malignancy. At the preoperative CT scan the left HV was not detectable, the middle HV was incorporated within the tumor, and right HV had a 3-cm contact with the tumor. No communicating veins were evident at preoperative imaging. RESULTS: After a J-shape thoracophrenolaparotomy, the resection of segments II-III-IVa was partially extended to segment VIII-VII and I. The right HV was detached from the tumor, and the middle HV was reconstructed with a 7-mm ringed-armed PTFE graft anastomosed to V8. Surgery lasted 20 h and 55 min with an estimated blood loss of 3500 ml, but the postoperative course was uneventful and the patient was discharged on the 14th postoperative day. One month later the CT scan showed a patent PTFE graft with the maturation of communicating-veins. One year later a complete thrombosis of the PTFE graft was observed with normal liver perfusion and function, and the patient was disease-free. CONCLUSIONS: PTFE-based parenchyma-sparing liver resection is a new tool to treat tumors located at the hepatocaval confluence exploiting the maturation of intrahepatic communicating-veins between main HV.

Minor-but-Complex Liver Resection: An Alternative to Major Resections for Colorectal Liver Metastases Involving the Hepato-Caval Confluence.

Major hepatectomy (MH) is often considered the only possible approach for colorectal liver metastasis (CRLM) at the hepato-caval confluence (CC), but it is associated with high morbidity and mortality. With the aim to reduce MH, we developed the "minor-but-complex" (MbC) technique, which consists in the resection of less than 3 adjacent liver segments with exposure of the CC and preservation of hepatic outflow until spontaneous maturation of peripheral intrahepatic shunts between main hepatic veins. We have evaluated applicability and outcome of MbC resections for the treatment of CRLM involving the CC. In this retrospective cohort study, all consecutive liver resections (LR) performed for CRLM located in segments 1, 7, 8, or 4a were classified as MINOR - removal of <3 adjacent segments; MbC - removal of <3 adjacent segments with CC exposure; and MH - removal of ≥ 3 adjacent segments. The rate of avoided MH was obtained by the difference between the rate of potentially MH (PMH) plus potentially inoperable cases and the rate of the MH performed. Taking into account that postoperative mortality is mainly related to the amount of resected liver, MbC was compared with minor resections for safety, complexity, and outcome. Of the 59 LR analyzed, 29 (49.1%) were deemed PMH and 4 (6.8%) potentially inoperable. Eventually, MH was performed only in 8 (13.5%) with a decrease rate of 42.4%. Minor LR was performed in 23 (39.0%) and MbC LR in 28 (47.5%) patients. Among MbC cases, 32.1% had previous liver treatments, 39.3% required vascular reconstruction (no reconstructed vessel thrombosis occurred before maturation of peripheral intrahepatic shunts between main hepatic veins), and 7.1% had grade IIIb-IV complications, their median hospital stay was 9 days and 90-day mortality was 0%. After a median follow-up of 22.2 months, oncological results were comparable with those of minor resections. MbC hepatectomy lowers the need for MH and allows for the resection of potentially inoperable patients without negative impact on safety and survival.

Optimization of in vitro HBV replication and HBsAg production in HuH7 cell line.

The Gunther's vector-free method (GM), using PCR-amplified full length HBV-DNA (fl-HBV-DNA), is currently the best in vitro HBV replication system despite the low intracellular HBV-DNA production. The replication efficiency and HBsAg secretion of 12 isolates from HBsAg/HBeAg positive sera by GM, Monomer-Linear-Sticky-Ends-DNA (MLSE) and Monomer-Circular-Closed (MCC) were compared in HuH7 cells. Eight of twelve genomes (67%) were replication competent by GM; however direct sequencing (DS) showed that more than 80% of input DNA was undigested in spite of SapI treatment. Replication Intermediates (RI) were detected earlier (24 vs. 48h) and in higher amounts (2.51±0.32 and 6.43±0.43 fold) by MCC than GM or MLSE. By MCC 10 of 12 genomes (83%) were replication competent and 7 produced high RI levels. RI and HBsAg kinetics correlated positively in MCC (R=0.696, p=0.017 overall; R=0.928, p=0.008), but not in GM (R=-0.437, p=0.179 overall; R=-0.395, p=0.439) in genotype D isolates. In conclusion, HBV-DNA circularization prior transfection improves in vitro viral replication and replication competent HBsAg production, mimicking better the in vivo conditions.

A novel immunosuppressive strategy combined with preemptive antiviral therapy improves the eighteen-month mortality in HCV recipients transplanted with aged livers.

BACKGROUND: Donor's age and immunosuppression influence the severity of hepatitis C virus (HCV) recurrence. We analyzed the 18-month mortality in 302 consecutive HCV recipients, divided into three groups, with homogeneous immunosuppression and preemptive antiviral therapy in the last group. PATIENTS: Group 1: one hundred thirty-three patients (1996-2000) mainly received a triple therapy (steroids- cyclosporine A [CyA]-azathioprine); first line treatment of biopsy-proven acute rejection (BPAR) was with steroid boluses; second-line with OKT3. Group 2: ninety-one patients (2001-2003) mainly received a double therapy (steroids-CyA) and induction with anti-CD25 antibody; first-line BPAR treatment was increased dose/switch of the calcineurin inhibitor; second-line steroid boluses; third-line extracorporeal photopheresis (ECP). Group 3: seventy-eight patients (2004-June 2006) mainly received a monotherapy (CyA) associated with ECP and induction with anti-CD25 antibody; first-line BPAR treatment was increased dose/switch of calcineurin inhibitor with increased ECP frequency, second-line steroid boluses, and third-line retransplantation. RESULTS: Median donor's age increased from 54 (13-84) years in group 1 to 60 (10-93) years in group 2 and 66 (17-84) years in group 3 (P<0.001). Overall mortality in groups 1, 2, and 3 decreased from 28.6% to 22% and 10.2% respectively (P = 0.003); HCV-related mortality from 7.5% and 12.1% to 1.3%, respectively (P = 0.029). BPAR were 33.8% in group 1 and 9.0% in group 3. Applicability of the preemptive antiviral therapy in group 3 was 69.2%. Sustained viral clearance occurred in 38.9% of 36 patients who completed the protocol. At multivariate analysis, a single-drug immunosuppressive regimen was the only variable independently associated with survival (P=0.05). CONCLUSION: Low and steady immunosuppression combined with preemptive antiviral therapy significantly improved the short-term mortality of HCV recipients transplanted with aged organs. Prolonged follow-up will assess whether this benefit is maintained in the long run.

Liver stiffness in the hepatitis B virus carrier: a non-invasive marker of liver disease influenced by the pattern of transaminases.

AIM: To investigate the usefulness of transient elastography by Fibroscan (FS), a rapid non-invasive technique to evaluate liver fibrosis, in the management of chronic hepatitis B virus (HBV) carriers. METHODS: In 297 consecutive HBV carriers, we studied the correlation between liver stiffness (LS), stage of liver disease and other factors potentially influencing FS measurements. In 87 chronic hepatitis B (CHB) patients, we monitored the FS variations according to the spontaneous or treatment-induced variations of biochemical activity during follow-up. RESULTS: FS values were 12.3 +/- 3.3 kPa in acute hepatitis, 10.3 +/- 8.8 kPa in chronic hepatitis, 4.3 +/- 1.0 kPa in inactive carriers and 4.6 +/- 1.2 kPa in blood donors. We identified the cut-offs of 7.5 and 11.8 kPa for the diagnosis of fibrosis >or= S3 and cirrhosis respectively, showing 93.9% and 86.5% sensitivity, 88.5% and 96.3% specificity, 76.7% and 86.7% positive predictive value (PPV), 97.3% and 96.3% negative predictive value (NPV) and 90.1% and 94.2% diagnostic accuracy. At multivariate analysis in 171 untreated carriers, fibrosis stage (t = 13.187, P < 0.001), active vs inactive HBV infection (t = 6.437, P < 0.001), alanine aminotransferase (ALT) (t = 4.740, P < 0.001) and HBV-DNA levels (t = or-2.046, P = 0.042) were independently associated with FS. Necroinflammation score (t = 2.158, > 10/18 vs

Comparable functions of plasmacytoid and monocyte-derived dendritic cells in chronic hepatitis C patients and healthy donors.

BACKGROUND/AIMS: Dendritic cells (DCs) play a key role in immune responses through antigen presentation and cytokine secretion. Hepatitis C virus (HCV) is able to escape elimination by the immune system and often establishes a chronic infection. To investigate whether DC dysfunction is involved in this process, we have studied monoycte-derived DCs (Mo-DCs) and plasmacytoid DCs (pDCs), which produce large amounts of IFN-alpha, from chronic HCV patients and healthy donors. METHODS: We have assessed TNF-alpha and IFN-alpha production by pDCs using intracellular staining after total PBMCs stimulation with unmethylated CG dinucleotides (CpGs). The induction of allogeneic T cell proliferation by immature Mo-DCs was measured using the MLR assay. The up-regulation of maturation markers and the production of TNF-alpha in response to LPS were analyzed using flow cytometry and ELISA, respectively. RESULTS: We have detected comparable frequencies of pDCs producing TNF-alpha and IFN-alpha in both chronic HCV patients and healthy donors and we have found that immature Mo-DCs from both patients and donors similarly induce allogeneic T cell proliferation and mature and secrete TNF-alpha in response to LPS. CONCLUSIONS: Our results demonstrate that both pDC and Mo-DCs are not impaired in HCV infected patients.

Association of hepatitis C virus envelope proteins with exosomes.

As the human tetraspanin CD81 binds hepatitis C virus (HCV) envelope glycoprotein E2, we addressed the role CD81 may play in cellular trafficking of HCV envelope proteins. Studies on HCV life cycle are complicated by the lack of a robust cell culture system; we therefore transfected mammalian cells with HCV E1-E2 cDNA, with or without human CD81 (huCD81) cDNA. In the absence of huCD81, HCV envelope proteins are almost completely retained in the endoplasmic reticulum. Instead, when huCD81 is present, a fraction of HCV envelope proteins passes through the Golgi apparatus, matures acquiring complex sugars and is found extracellularly associated with exosomes. These are 60-100-nm membrane vesicles enriched in tetraspanins, released into the extracellular milieu by many cell types and having fusogenic activity. We also report that human plasma contains exosomes and that in HCV patients, viral RNA is associated with these circulating vesicles. We propose that the HCV-CD81 complex leaves cells in the form of exosomes, circulates in this form and exploits the fusogenic capabilities of these vesicles to infect cells even in the presence of neutralizing antibodies.