Extracellular vesicles (EVs) are increasingly recognized as important mediators of intercellular communication. In this study, we aimed to further characterize the role of macrophage-derived EVs in immune responses against hepatitis C virus (HCV) and the potential of polyunsaturated fatty acids (PUFAs) to modulate this modality of innate immunity. To this end, EVs were isolated from interferon-stimulated macrophage cultures or from serum of patients with acute or chronic hepatitis C. EVs were characterized by electron microscopy, flow cytometry, RNA-sequencing, and Western blot analysis. The effect of EVs on replication of HCV was assessed in coculture models. Functional analyses were performed to assess the impact of PUFAs on EV-mediated antiviral immunity. We found that macrophages secreted various cytokines shortly after stimulation with type I and II IFN, which orchestrated a fast but short-lasting antiviral state. This rapid innate immune answer was followed by the production of macrophage-derived EVs, which induced a late, but long-lasting inhibitory effect on HCV replication. Of note, exposure of macrophages to PUFAs, which are important regulators of immune responses, dampened EV-mediated antiviral immune responses. Finally, EVs from patients with hepatitis C exhibited long-lasting antiviral activities during IFN therapy as well. The antiviral effect of EVs from Caucasian and Japanese patients differed, which may be explained by different nutritional uptake of PUFAs. In conclusion, our data indicate that macrophage-derived EVs mediate long-lasting inhibitory effects on HCV replication, which may bridge the time until efficient adaptive immune responses are established, and which can be blunted by PUFAs.

Vaccination against SARS-CoV-2 infection is currently approved and shows favorable outcomes, but little known about antibody responses in solid organ transplant recipients, since these patients are known to have an impaired immune response upon vaccination and have not been included in admission studies. We therefore analyzed immunogenicity in 43 liver transplant (LT) recipients in a median of 15 days (IQR, 12–24) after receiving two doses of the mRNA-based SARS-CoV-2 vaccine BNT162b2 following the standard protocol, and compared these results to a control group consisting of 20 healthcare workers (HCWs). Thirty-four of the 43 (79%) LT recipients developed antibodies, compared to 20 out of 20 (100%) in the control group (p = 0.047). The median SARS-CoV-2 IgG titer was significantly lower in the LT recipients compared to the control group (216 vs. >2080 BAU/mL, p = 0.0001). Age and sex distribution was similar in the LT patients that developed antibodies after vaccination compared to those who did not. Interestingly, the patients who received mycophenolate mofetil exhibited a reduced vaccination response compared to the other LT patients (5 of 11 (45.5%) vs. 29 of 32 (90.6%), p = 0.004). In conclusion, our data reveal lower immunogenicity of SARS-CoV-2 vaccine BNT162b2 in LT patients compared to the control group, but still show superior results compared to other solid organ transplant recipients reported so far.

Introduction: Acute-on-chronic liver failure (ACLF) is characterized by high levels of systemic inflammation and parallel suppression of innate immunity, whereas little is known about adaptive immune immunity in ACLF. We therefore aimed to characterize the development of the adaptive immune system during the progression of liver cirrhosis to ACLF. Patients with compensated/stable decompensated liver cirrhosis, acute decompensation of liver cirrhosis, or ACLF were recruited from a prospective cohort study. Comprehensive immunophenotyping was performed using high dimensional flow cytometry. Replication of Torque teno (TT) virus was quantified as a marker of immunosuppression. High frequencies of detectable TT virus were observed already in patients with compensated/stable decompensated liver cirrhosis compared to healthy controls (>50% vs. 19%), suggesting relatively early occurrence of immunosuppression in cirrhosis. In line, profoundly reduced numbers of distinct innate and adaptive immune cell populations were observed before ACLF development. These changes were accompanied by parallel upregulation of co-stimulatory (e.g. CD40L, OX40, CD69, GITR, TIM-1) and inhibitory immune checkpoints (e.g. PDPN, PROCR, 2B4, TIGIT) on CD4+ and CD8+ T cells, which again preceded the development of ACLF. On a functional basis, the capacity of CD4+ and CD8+ T cells to produce pro-inflammatory cytokines upon stimulation was strongly diminished in patients with acute decompensation of liver cirrhosis and ACLF.Conclusion: Impaired innate and—in particular—adaptive cellular immunity occurs relatively early in the pathogenesis of liver cirrhosis and precedes ACLF. This may contribute to the development of ACLF by increasing the risk of infections in patients with liver cirrhosis.

Despite vaccination programs and direct antiviral treatments, the incidence of virus-related hepatocellular carcinoma (HCC) remains high, while ultrasound-based detection rates for early-stage HCC is continuously low. To address this insufficiency, we set out to characterize whether the GALAD score, which incorporates gender, age, and serum levels of AFP, AFP isoform L3 (AFP-L3), and des-gamma-carboxy-prothrombin (DCP), can improve early-stage HCC detection in a Caucasian HBV/HCV cohort. In a retrospective German single-center study, 182 patients with HBV, 223 with HCV and 168 with other etiology (OE) of chronic liver disease (CLD) were enrolled. HCC was confirmed in 52 HBV, 84 HCV and 60 OE CLD patients. The diagnostic performance of the single biomarkers in HCC detection was compared to the GALAD model. At initial diagnosis, most patients were at (very) early BCLC 0 (n = 14/7%) or A (n = 56/29%) or intermediate stage BCLC B (n = 93/47%) HCC in all three subgroups. In the BCLC 0/A cohort, GALAD exhibited an AUC of 0.94 discriminating HCC from non-HCC, surpassing AFP (AUC 0.86), AFP-L3 (AUC 0.83) and DCP (AUC 0.83). In the HBV population, GALAD achieved an AUC of 0.96, in HCV an AUC of 0.98 and in OE an AUC of 0.99, clearly superior to the biomarkers alone. Furthermore, in HCV patients GALAD showed a significantly higher specificity (89%) versus AFP (64%) alone. In chronic viral hepatitis, the GALAD model showed superior performance in detection of early-stage HCC, while exhibiting higher specificity in HCV patients compared to AFP alone. We conclude that the GALAD score shows potential for HCC surveillance in Caucasian HBV/HCV patients.

The efficacy of antibiotic prophylaxis to prevent spontaneous bacterial peritonitis (SBP) in patients colonized with multidrug-resistant organisms (MDROs) is unknown. We evaluated the effectiveness of fluoroquinolone-based SBP prophylaxis in an era and area of frequent antibiotic resistance. This is a prospective observational study in patients with liver cirrhosis and an indication for fluoroquinolone-based prophylaxis of SBP. Patients were recruited and followed in a large German tertiary reference center with comprehensive microbiological and clinical monitoring performed at baseline and after 30, 60, 90, and 180 days of prophylaxis. Overall, 77 patients received antibiotic prophylaxis for an average of 93 days. Baseline prevalence of colonization with MDROs was high (N = 39, 50.6%). At least one de novo MDRO was detected in 27 patients (35.1%) during antibiotic prophylaxis; 33 patients (42.9%) developed secondary infections, including 14 cases (17.9%) of infections with MDROs, and 13 cases (16.9%) of de novo/recurrent SBP. Thirty patients (39.0%) died during follow-up. Significantly higher risks of SBP development during antibiotic prophylaxis were observed for patients with versus without any apparent MDROs (P = .009), vancomycin-resistant enterococci (P = .008), multidrug-resistant gram-negative bacteria (P = .016), or quinolone-resistant gram-negative bacteria (QR-GNB) (P = .015). In competing risk analysis, QR-GNB were independently associated with prophylaxis failure (hazard ratio, 3.39; P = .045) and infections with QR-GNB were independently associated with death before SBP (subdistribution hazard risk, 6.47; P = .034). Antibiotic prophylaxis of SBP appears to be less efficient in patients with known MDROs. Regular MDRO screening seems to be useful to tailor treatment of secondary infections and re-evaluate antibiotic prophylaxis in case of selection of quinolone resistance.