Impending HCC diagnosis in patients with cirrhosis after HCV cure features a natural killer cell signature

BACKGROUND AND AIMS

The risk of developing HCC in chronically infected patients with AQ2 HCV with liver cirrhosis is significantly elevated. This risk remains high even after a sustained virological response with direct-acting antivirals. To date, disease-associated signatures of NK cells indicating HCC development are unclear.

APPROACH AND RESULTS

This study investigated NK cell signatures and functions in 8 cohorts covering the time span of HCC development, diagnosis, and onset. In-depth analysis of NK cell profiles from patients with cirrhosis who developed HCC (HCV-HCC) after sustained virological response compared with those who remained tumor-free (HCV-noHCC) revealed increasingly dissimilar NK cell signatures over time. We identified expression patterns with persistently high frequencies of TIM-3 and CD38 on NK cells that were largely absent in healthy controls and were associated with a high probability of HCC development. Functional assays revealed that the NK cells had potent cytotoxic features. In contrast to HCV-HCC, the signature of HCV-noHCC converged with the signature found in healthy controls over time. Regarding tissue distribution, single-cell sequencing showed high frequencies of these cells in liver tissue and the invasive margin but markedly lower frequencies in tumors.

CONCLUSIONS

We show that HCV-related HCC development has profound effects on the imprint of NK cells. Persistent co-expression of TIM-3hi and CD38 + on NK cells is an early indicator for HCV-related HCC development. We propose that the profiling of NK cells may be a rapid and valuable tool to assess the risk of HCC development in a timely manner in patients with cirrhosis after HCV cure.

Individual Epitope-Specific CD8+ T Cell Immune Responses Are Shaped Differently during Chronic Viral Infection

A hallmark in chronic viral infections are exhausted antigen-specific CD8⁺ T cell responses and the inability of the immune system to eliminate the virus. Currently, there is limited information on the variability of epitope-specific T cell exhaustion within one immune response and the relevance to the T cell receptor (TCR) repertoire. The aim of this study was a comprehensive analysis and comparison of three lymphocytic choriomeningitis virus (LCMV) epitope-specific CD8⁺ T cell responses (NP396, GP33 and NP205) in a chronic setting with immune intervention, e.g., immune checkpoint inhibitor (ICI) therapy, in regard to the TCR repertoire. These responses, though measured within the same mice, were individual and independent from each other. The massively exhausted NP396-specific CD8⁺ T cells revealed a significantly reduced TCR repertoire diversity, whereas less-exhausted GP33-specific CD8⁺ T cell responses were rather unaffected by chronicity in regard to their TCR repertoire diversity. NP205-specific CD8⁺ T cell responses showed a very special TCR repertoire with a prominent public motif of TCR clonotypes that was present in all NP205-specific responses, which separated this from NP396- and GP33-specific responses. Additionally, we showed that TCR repertoire shifts induced by ICI therapy are heterogeneous on the epitope level, by revealing profound effects in NP396-, less severe and opposed effects in NP205-, and minor effects in GP33-specific responses. Overall, our data revealed individual epitope-specific responses within one viral response that are differently affected by exhaustion and ICI therapy. These individual shapings of epitope-specific T cell responses and their TCR repertoires in an LCMV mouse model indicates important implications for focusing on epitope-specific responses in future evaluations for therapeutic approaches, e.g., for chronic hepatitis virus infections in humans.

Application of CT contrast medium is not associated with an increased risk for acute kidney injury in patients with decompensated cirrhosis

BACKGROUND

Acute kidney injury (AKI) is a frequent complication in patients with decompensated cirrhosis. Studies reported conflicting results regarding the nephrotoxic potential of iodinated contrast medium (CM) for computer tomography (CT).

AIM

To investigate the impact of diagnostic CM application on kidney function in patients with decompensated cirrhosis.

METHODS

First, we evaluated the impact of diagnostic CM-CT on AKI incidence in a cross-sectional approach. Second, we analysed 28-day AKI incidence post-CM-CT in patients with impaired kidney function (i.e., creatinine >133 μmoL/L). Third, we excluded all patients with relevant interventions besides CM-CT. All remaining patients were matched via propensity score matching (PPSM) and further analysed. Last, we validated the results in an independent dataset of prospectively collected registry data of 118 patients with decompensated cirrhosis. Here, plasma samples were analysed regarding neutrophil-gelatinase-associated-lipocalin (NGAL).

RESULTS

Of the 611 included patients, 98 (16%) received CM-CT. CM-CT was not associated with AKI in the cross-sectional approach (CM-CT:8% vs. no CM-CT:15%; p = 0.08). Furthermore, CM-CT was not associated with higher 28-day AKI incidence among patients with impaired kidney function (HR:0.79; 95% CI 0.45-1.38; p = 0.40). The PPSM cohort revealed no association between CM-CT and AKI or severe AKI (HR:1.28, p = 0.45 and HR:1.62; p = 0.43). Moreover, CM-CT did not result in worsening of kidney function after CM application. In the validation cohort, CM-CT was also not linked to AKI (p = 0.85) and NGAL levels were not increased in those with CM-CT (CM-CT:309 ng/ml vs. No CM-CT:266 ng/ml, p = 0.35).

CONCLUSION

Decompensated cirrhosis per se should not preclude diagnostic CM-CT.

Reverse inflammaging: Long-term effects of HCV cure on biological age

BACKGROUND & AIMS

Chronic hepatitis C virus (HCV) infection can be cured with direct-acting antivirals (DAAs). However, not all sequelae of chronic hepatitis C appear to be completely reversible after sustained virologic response (SVR). Recently, chronic viral infections have been shown to be associated with biological age acceleration defined by the epigenetic clock. The aim of this study was to investigate whether chronic HCV infection is associated with epigenetic changes and biological age acceleration and whether this is reversible after SVR.

METHODS

We included 54 well-characterized individuals with chronic hepatitis C who achieved SVR after DAA therapy at three time points: DAA treatment initiation, end of treatment, and long-term follow-up (median 96 weeks after end of treatment). Genome-wide DNA methylation status was determined in peripheral blood mononuclear cells (PBMCs) and used to calculate epigenetic age acceleration (EAA) using Horvath's clock.

RESULTS

Individuals with HCV had an overall significant EAA of 3.12 years at baseline compared with -2.61 years in the age- and sex-matched reference group (p <0.00003). HCV elimination resulted in a significant long-term increase in DNA methylation dominated by hypermethylated CpGs in all patient groups. Accordingly, EAA decreased to 1.37 years at long-term follow-up. The decrease in EAA was significant only between the end of treatment and follow-up (p = 0.01). Interestingly, eight individuals who developed hepatocellular carcinoma after SVR had the highest EAA and showed no evidence of reversal after SVR.

CONCLUSIONS

Our data contribute to the understanding of the biological impact of HCV elimination after DAA therapy and demonstrate that HCV elimination can lead to "reverse inflammaging". In addition, our data support the potential use of biological age as a biomarker for HCV sequelae after SVR.

IMPACT AND IMPLICATIONS

Chronic hepatitis C virus infection is now curable with direct-acting antivirals, but it remains unclear whether hepatitis C sequelae are fully reversible after viral elimination. Our results suggest that epigenetic changes or acceleration of biological age are reversible in principle, but this requires time, while a lack of reversibility appears to be associated with the development of hepatocellular carcinoma. While most clinical risk scores now take chronological age into account, it may be worthwhile to explore how biological age might improve these scores in the future. Biological age may be a cornerstone for the individualized clinical assessment of patients in the future, as it better reflects patients' lifestyle and environmental exposures over decades.

Impact of HBsAg and HBcrAg levels on phenotype and function of HBV-specific T cells in patients with chronic hepatitis B virus infection

OBJECTIVE

Hepatitis B virus (HBV)-specific T cells are main effector cells in the control of HBV infection and hepatitis B surface antigen (HBsAg) is suggested to be a critical factor in the impaired immune response, a hallmark of chronic HBV infection. In addition to HBsAg, other viral markers such as hepatitis B core-related antigen (HBcrAg) are available, but their potential association with HBV-specific immune responses is not defined yet, which will be important if these markers are used for patient stratification for novel therapies aimed at functional HBV cure.

DESIGN

We analysed T cell responses in 92 patients with hepatitis B e antigen negative chronic HBV infection with different HBsAg and HBcrAg levels. Overlapping peptides were used for in vitro response analyses (n=57), and HBV core₁₈-specific and polymerase (pol)₄₅₅-specific CD8⁺ T cells were assessed in human leukocyte antigen (HLA)-A*02 patients (n=35). In addition, in vitro responsiveness to anti-programmed cell death-ligand 1 (anti-PD-L1) was investigated.

RESULTS

HBV-specific T cell responses were not affected by HBsAg levels, but rather by age and CD4⁺ T cell responses were highest in patients with low HBcrAg levels. The phenotypes and functionality of HBV core₁₈-specific and pol₄₅₅-specific CD8⁺ T cells differed, but HBsAg and HBcrAg levels did not affect their profiles. Blocking with anti-PD-L1 could restore HBV-specific T cells, but the effect was significantly higher in T cells isolated from patients with low HBsAg and in particular low HBcrAg.

CONCLUSION

Our data suggest that age and HBcrAg rather than HBsAg, are associated with HBV-specific T cell responses. Finally, very low antigen levels indicated by HBsAg and in particular HBcrAg may influence T cell response to checkpoint inhibition.

Metamizole-Associated Risks in Decompensated Hepatic Cirrhosis

BACKGROUND

Because of the increased risk of acute renal failure (ARF), the use of cyclooxygenase (COX) inhibitors is not recommended in patients with decompensated hepatic cirrhosis. Metamizole is not a classic COX inhibitor, but there are insufficient data to support its safe use. In this study, we investigate the effect of metamizole on the risk of ARF in these patients.

METHODS

Metamizole use, ARF incidence, and patient mortality were examined in a large, retrospective, exploratory cohort and validated with data from a prospective registry.

RESULTS

523 patients were evaluated in the exploratory cohort. Metamizole use at baseline was documented in 110 cases (21%) and was independently associated with the development of ARF, severe (grade 3) ARF, and lower survival without liver transplantation at follow-up on day 28 (HR: 2.2, p < 0.001; HR: 2.8, p < 0.001; and HR: 2.6, p < 0.001, respectively). Interestingly, the risk of ARF depended on the dose of metamizole administered (HR: 1.038, p < 0.001). Compared to patients who were treated with opioids, the rate of ARF was higher in the metamizole group (49% vs. 79%, p = 0.014). An increased risk of ARF with metamizole use was also demonstrated in the independent validation cohort (p < 0.001).

CONCLUSION

Metamizole therapy, especially at high doses, should only be used with a high level of caution in patients with decompensated cirrhosis.

COVID-19 immune signatures reveal stable antiviral T cell function despite declining humoral responses

Cellular and humoral immunity to SARS-CoV-2 is critical to control primary infection and correlates with severity of disease. The role of SARS-CoV-2-specific T cell immunity, its relationship to antibodies, and pre-existing immunity against endemic coronaviruses (huCoV), which has been hypothesized to be protective, were investigated in 82 healthy donors (HDs), 204 recovered (RCs), and 92 active COVID-19 patients (ACs). ACs had high amounts of anti-SARS-CoV-2 nucleocapsid and spike IgG but lymphopenia and overall reduced antiviral T cell responses due to the inflammatory milieu, expression of inhibitory molecules (PD-1, Tim-3) as well as effector caspase-3, -7, and -8 activity in T cells. SARS-CoV-2-specific T cell immunity conferred by polyfunctional, mainly interferon-γ-secreting CD4⁺ T cells remained stable throughout convalescence, whereas humoral responses declined. Immune responses toward huCoV in RCs with mild disease and strong cellular SARS-CoV-2 T cell reactivity imply a protective role of pre-existing immunity against huCoV.

Pilot Study Using Machine Learning to Identify Immune Profiles for the Prediction of Early Virological Relapse After Stopping Nucleos(t)ide Analogues in HBeAg-Negative CHB

Treatment with nucleos(t)ide analogues (NAs) may be stopped after 1-3 years of hepatitis B virus DNA suppression in hepatitis B e antigen (HBeAg)-negative patients according to Asian Pacific Association for the Study of Liver and European Association for the Study of Liver guidelines. However, virological relapse (VR) occurs in most patients. We aimed to analyze soluble immune markers (SIMs) and use machine learning to identify SIM combinations as predictor for early VR after NA discontinuation. A validation cohort was used to verify the predictive power of the SIM combination. In a post hoc analysis of a prospective, multicenter therapeutic vaccination trial (ABX-203, NCT02249988), hepatitis B surface antigen, hepatitis B core antigen, and 47 SIMs were repeatedly determined before NA was stopped. Forty-three HBeAg-negative patients were included. To detect the highest predictive constellation of host and viral markers, a supervised machine learning approach was used. Data were validated in a different cohort of 49 patients treated with entecavir. VR (hepatitis B virus DNA ≥ 2,000 IU/mL) occurred in 27 patients. The predictive value for VR of single SIMs at the time of NA stop was best for interleukin (IL)-2, IL-17, and regulated on activation, normal T cell expressed and secreted (RANTES/CCL5) with a maximum area under the curve of 0.65. Hepatitis B core antigen had a higher predictive power than hepatitis B surface antigen but lower than the SIMs. A supervised machine-learning algorithm allowed a remarkable improvement of early relapse prediction in patients treated with entecavir. The combination of IL-2, monokine induced by interferon γ (MIG)/chemokine (C-C motif) ligand 9 (CCL9), RANTES/CCL5, stem cell factor (SCF), and TNF-related apoptosis-inducing ligand (TRAIL) was reliable in predicting VR (0.89; 95% confidence interval: 0.5-1.0) and showed viable results in the validation cohort (0.63; 0.1-0.99). Host immune markers such as SIMs appear to be underestimated in guiding treatment cessation in HBeAg-negative patients. Machine learning can help find predictive SIM patterns that allow a precise identification of patients particularly suitable for NA cessation.

TOX defines the degree of CD8+ T cell dysfunction in distinct phases of chronic HBV infection

OBJECTIVE

Chronic hepatitis B virus (HBV) infection is characterised by HBV-specific CD8+ T cell dysfunction that has been linked to Tcell exhaustion, a distinct differentiation programme associated with persisting antigen recognition. Recently, Thymocyte Selection-Associated High Mobility Group Box (TOX) was identified as master regulator of CD8+ T cell exhaustion. Here, we addressed the role of TOX in HBV-specific CD8+ T cell dysfunction associated with different clinical phases of infection.

DESIGN

We investigated TOX expression in HBV-specific CD8+ T cells from 53 HLA-A*01:01, HLA-A*11:01 and HLA-A*02:01 positive patients from different HBV infection phases and compared it to hepatitis C virus (HCV)-specific, cytomegalovirus (CMV)-specific, Epstein-Barr virus (EBV)-specific and influenza virus (FLU)-specific CD8+ T cells. Phenotypic and functional analyses of virus-specific CD8+ T cells were performed after peptide-loaded tetramer-enrichment and peptide-specific expansion.

RESULTS

Our results show that TOX expression in HBV-specific CD8+ T cells is linked to chronic antigen stimulation, correlates with viral load and is associated with phenotypic and functional characteristics of T-cell exhaustion. In contrast, similar TOX expression in EBV-specific and CMV-specific CD8+ T cells is not linked to T-cell dysfunction suggesting different underlying programmes. TOX expression in HBV-specific CD8+ T cells is also affected by targeted antigens, for example, core versus polymerase. In HBV-specific CD8+ T cells, TOX expression is maintained after spontaneous or therapy-mediated viral control in chronic but not self-limiting acute HBV infection indicating a permanent molecular imprint after chronic but not temporary stimulation.

CONCLUSION

Our data highlight TOX as biomarker specific for dysfunctional virus-specific CD8+ T cells in the context of an actively persisting infection.

MAIT Cells Are Enriched and Highly Functional in Ascites of Patients With Decompensated Liver Cirrhosis

BACKGROUND AND AIMS

Patients with advanced liver cirrhosis have an increased susceptibility to infections. As part of the cirrhosis-associated immune dysfunction, mucosal-associated invariant T (MAIT) cells, which have the capacity to respond to bacteria, are severely diminished in circulation and liver tissue. However, MAIT cell presence and function in the peritoneal cavity, a common anatomical site for infections in cirrhosis, remain elusive. In this study, we deliver a comprehensive investigation of the immune compartment present in ascites of patients with decompensated liver cirrhosis, and focus especially on MAIT cells.

APPROACH AND RESULTS

To study this, matched peripheral blood and ascites fluid were collected from 35 patients with decompensated cirrhosis, with or without spontaneous bacterial peritonitis (SBP). MAIT cell phenotype and function were analyzed using high-dimensional flow cytometry, and the obtained data were compared with the blood samples of healthy controls (n = 24) and patients with compensated cirrhosis (n = 11). We found circulating MAIT cells to be severely decreased in patients with cirrhosis as compared with controls. In contrast, in ascites fluid, MAIT cells were significantly increased together with CD14⁺ CD16⁺ monocytes, innate lymphoid cells, and natural killer cells. This was paralleled by elevated levels of several pro-inflammatory cytokines and chemokines in ascites fluid as compared with plasma. Peritoneal MAIT cells displayed an activated tissue-resident phenotype, and this was corroborated by increased functional responses following stimulation with E. coli or interleukin (lL)-12 + IL-18 as compared with circulating MAIT cells. During SBP, peritoneal MAIT cell frequencies increased most among all major immune cell subsets, suggestive of active homing of MAIT cells to the site of infection.

CONCLUSIONS

Despite severely diminished MAIT cell numbers and impaired phenotype in circulation, peritoneal MAIT cells remain abundant, activated, and highly functional in decompensated cirrhosis and are further enriched in SBP. This suggests that peritoneal MAIT cells could be of interest for immune-intervention strategies in patients with decompensated liver cirrhosis and SBP.

Soluble immune markers in the different phases of chronic hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection may follow four different consecutive phases, which are defined by virology as well as biochemical markers and differ in terms of prognosis and need for antiviral treatment. Currently, host responses reflected by immune markers are not considered in this definition. We aimed to study soluble immune markers and their distribution in different phases of chronic HBV infection. In this cross-sectional retrospective study, we investigated a panel of 14 soluble immune markers (SIM) including CXCL10 in 333 patients with chronic HBV infection. In a small cohort of HBeAg positive patients we analyzed SIM before and after HBeAg seroconversion and compared seroconverters to patients with unknown outcome. Significant differences were documented in the levels of several SIM between the four phases of chronic HBV infection. The most pronounced difference among all investigated SIM was observed for CXCL10 concentrations with highest levels in patients with hepatitis. TGF-β and IL-17 revealed different levels between HBeAg negative patients. HBeAg positive patients with HBeAg seroconversion presented higher amounts of IL-12 before seroconversion compared to HBeAg positive patients with unknown follow up. SIM such as CXCL10 but also IL-12, TGF-β and IL-17 may be useful markers to further characterize the phase of chronic HBV infection.

Hepatitis B virus-specific T cell responses after stopping nucleos(t)ide analogue therapy in HBeAg-negative chronic hepatitis B

BACKGROUND & AIMS

Treatment with nucleos(t)ide analogues (NA) leads to hepatitis B virus (HBV) DNA suppression in most patients with chronic hepatitis B (CHB), but HBV surface antigen (HBsAg) loss rates are low. Upon NA discontinuation, HBV DNA can return rapidly with ensuing alanine aminotransferase flares and induction of cytokines. Several studies reported higher HBsAg loss rates after stopping therapy, but at present it is unclear if cell-mediated immune responses are altered after treatment discontinuation. The aim of this study was to characterise T cell responses during the early phase of virological relapse, following discontinuation of NA therapy in HBeAg-negative patients.

METHODS

A total of 15 HBeAg-negative patients with CHB on long-term NA treatment were included in a prospective study and subjected to structured NA discontinuation. T cell responses were studied at the end of NA therapy and 4, 8 and 12 weeks thereafter.

RESULTS

The T cell phenotype of patients with CHB on long-term NA therapy was markedly different compared to healthy individuals, but was only slightly altered after discontinuation of therapy. T cells from patients with HBsAg loss expressed low levels of KLRG1 and PD-1 at all time-points and high levels of Ki-67 and CD38 at week 12 after treatment cessation. In vitro peptide stimulated HBV-specific T cell responses were increased in several patients after NA cessation. Blocking of PD-L1 further enhanced HBV-specific T cell responses, especially after discontinuation of therapy.

CONCLUSION

Relapse of active HBV replication after stopping therapy may trigger an immunological environment that enhances the responsiveness of HBV-specific T cells in vitro. Together with other immune interventions, this approach might be of interest for the development of novel therapeutic options to induce HBsAg loss in CHB.

LAY SUMMARY

Relapse of hepatitis B virus replication after discontinuation of nucleos(t)ide analogue therapy in certain patients with chronic hepatitis B may alter the phenotype of T cells and enhance the responsiveness of hepatitis B virus-specific T cells to in vitro peptide stimulation. Blocking PD-L1 can further augment these hepatitis B virus-specific T cell responses. Interestingly, T cells of patients that subsequently achieve hepatitis B surface antigen loss are less exhausted at all time-points after stopping treatment and display a higher proliferative capacity 12-weeks after treatment discontinuation. These findings contribute to the understanding of the immunological events that occur during discontinuation of nucleos(t)ide analogue therapy.

Hepatitis E virus ORF 1 induces proliferative and functional T-cell responses in patients with ongoing and resolved hepatitis E

BACKGROUND AND AIMS

Hepatitis E virus (HEV) is a major cause of acute viral hepatitis with >3 million symptomatic cases per year accounting for 70 000 HEV-related deaths. HEV-specific T-cell responses have been investigated against structural proteins expressed by open reading frames (ORF) 2 and 3. T-cell responses against non-structural HEV proteins encoded by ORF1 are hardly studied. The aim of this study was to determine HEV ORF1-specific T-cell responses in comparison to ORF2/3 in patients exposed to HEV.

METHODS

HEV-specific CD4⁺ and CD8⁺ T-cell responses against HEV genotype 3 were investigated in patients with acute and chronic hepatitis E as well as in HEV seropositive and seronegative individuals. HEV-specific T-cell responses were determined by proliferation and intracellular cytokine assay upon stimulation of PBMCs with HEV-specific overlapping peptide pools spanning the entire HEV genome. HEV-antigen was measured using an anti-HEV antigen-specific ELISA.

RESULTS

Broad HEV ORF1-specific T-cell responses were detected in patients with acute, resolved and chronic hepatitis E without distinct dominant regions. The magnitude and frequency in recognition of ORF1-specific T-cell responses were similar compared to responses against HEV ORF2/3. Longitudinal studies of HEV-specific T-cell responses displayed similar behaviour against structural and non-structural proteins. HEV-antigen levels were inversely correlated with HEV-specific T-cell responses.

CONCLUSIONS

HEV-specific T-cell responses are detectable against the entire HEV genome including the non-structural proteins. HEV-specific T-cell responses are associated with control of HEV infection. These findings have implications for the design of HEV vaccines.

Hepatitis E virus-induced primary cutaneous CD30(+) T cell lymphoproliferative disorder

BACKGROUND & AIM

Several types of unexplained extra-hepatic manifestations, including haematological disorders, have been reported in the context of hepatitis E virus (HEV) infection. However, the underlying mechanism(s) of these manifestations are unknown. We provide evidence that HEV has an extra-hepatic endothelial tropism that can engage cutaneous T cells towards clonality.

METHODS

A patient with a CD30(+) cutaneous T cell lymphoproliferative disorder (T-LPD) and biopsy-proven chronic HEV infection received three rounds of oral ribavirin treatment, administered either without or with interferon, and eventually achieved a sustained virologic response (SVR). Pathologic, virologic and immunologic investigations were carried out on biopsied skin lesion, and peripheral blood mononuclear cells between the 2nd and 3rd round of antiviral treatment and biopsied liver.

RESULTS

Remission of T-LPD was observed upon antiviral treatment, and the patient remained in complete remission after achieving SVR. The T cell analysis showed large CD30(+) lymphocytes surrounding the blood vessels within the CD8(+) T cell infiltrate. HEV was detected within dermal microvascular endothelial cells using immunofluorescence staining, in situ hybridisation and electron microscopy. Infiltrating T cells mostly comprised memory CD8(+) T cells with a tissue-resident memory T cell phenotype. Overall, 98% of extracted T cells were CD8(+) T cells with aVβ signature skewed towards Vβ4 and with an oligoclonal profile. T cell clones from T-LPD were more like T cells in the liver than T cells in the blood [odds ratio=4.55, (3.70-5.60), p<0.0001]. No somatic mutations were found in the T-LPD exomes.

CONCLUSION

HEV has an extra-hepatic tissue tropism in humans, including dermal endothelium, and can induce CD30(+) T-LPD that is sensitive to antivirals.

LAY SUMMARY

Hepatitis E virus (HEV) has an extra-hepatic tissue tropism and should be added to the list of viruses associated with lymphoproliferative disorders. As such, HEV should be part of the laboratory workup of any lymphoproliferation, particularly those of the T cell phenotype that involve the skin. In the context of HEV-associated cutaneous T cell lymphoproliferative disorders, antiviral treatment could be considered a first-line treatment instead of chemotherapy.

Cross-genotype-specific T-cell responses in acute hepatitis E virus (HEV) infection

Hepatitis E is an inflammatory liver disease caused by infection with the hepatitis E virus (HEV). In tropical regions, HEV is highly endemic and predominantly mediated by HEV genotypes 1 and 2 with >3 million symptomatic cases per year and around 70 000 deaths. In Europe and America, the zoonotic HEV genotypes 3 and 4 have been reported with continues increasing new infections per year. So far, little is known about T-cell responses during acute HEV genotype 3 infection. Therefore, we did a comprehensive study investigating HEV-specific T-cell responses using genotypes 3- and 1-specific overlapping peptides. Additional cytokines and chemokines were measured in the plasma. In four patients, longitudinal studies were performed. Broad functional HEV-specific CD4(+) and CD8(+) T-cell responses were detectable in patients acutely infected with HEV genotype 3. Elevated of pro- and anti-inflammatory cytokine levels during acute HEV infection correlated with ALT levels. Memory HEV-specific T-cell responses were detectable up to >1.5 years upon infection. Importantly, cross-genotype HEV-specific T-cell responses (between genotypes 1 and 3) were measurable in all investigated patients. In conclusion, we could show for the first time HEV-specific T-cell responses during and after acute HEV genotype 3 infection. Our data of cross-genotype HEV-specific T-cell responses might suggest a potential role in cross-genotype-specific protection between HEV genotypes 1 and 3.

Altered effector functions of NK cells in chronic hepatitis C are associated with IFNL3 polymorphism

Interferon α-mediated effector functions of NK cells may contribute to the control of HCV replication and the pathogenesis of liver disease. The single-nucleotide polymorphism rs12979860 near IFNL3 (previously known as IL28B) is important in response to IFN-α treatment and in spontaneous resolution of acute hepatitis C. The role of the IFNL3 polymorphism in NK cell function is unclear. Thus, we investigated the role of IFNL3 polymorphism in type I IFN-dependent regulation of NK cell functions in patients with cHC and healthy control subjects. We demonstrated a marked polarization of NK cells toward cytotoxicity in response to IFN-α stimulation in patients with hepatitis C. That TRAIL up-regulation was present, particularly in patients with the IFNL3-TT allele, was supported by a shift in the pSTAT-1:pSTAT-4 ratios toward pSTAT-1. In patients bearing the IFNL3-TT allele, NK cell effector function correlated with liver disease activity. In contrast, higher cytokine production of NK cells was observed in healthy individuals with the IFNL3-CC genotype, which may support spontaneous HCV clearance in acute infection. Overall, these findings show that the role of NK cells may differ in chronic infection vs. early antiviral defense and that the IFNL3 genotype differentially influences NK cell function.

Comprehensive phenotyping of regulatory T cells after liver transplantation

Regulatory T cells (Tregs) play an important role in controlling alloreactivity after solid organ transplantation, but they may also impair antiviral immunity. We hypothesized that the Treg frequency and the Treg phenotype are altered in hepatitis C virus (HCV)-infected recipients of liver transplantation (LT) with possible prognostic implications. Tregs from 141 individuals, including healthy individuals, LT recipients with or without persistent HCV infections, and nontransplant patients with chronic HCV, were studied. A comprehensive phenotypic analysis was performed with multicolor flow cytometry, which included standard Treg markers [CD4(+), CD25(hi), CD127(-), and FoxP3(+) in addition to HLA DR, CCR7, CD45RA, CD62L, CD49d, CD39, ICOS and LAP-TGFβ stainings. Healthy individuals and LT patients displayed similar Treg frequencies and largely comparable Treg phenotypes, which were stable over time after transplantation. In contrast, Tregs with a CD45RA(-) CCR7(-) effector phenotype were enriched in LT recipients with chronic HCV versus HCV-negative transplant patients. HCV infection, rather than LT, altered the expression of functional markers on Tregs. A principal component analysis revealed distinct Treg phenotypes in HCV-infected LT recipients with rejection and patients with recurrent graft HCV. In conclusion, Treg phenotypes are altered in HCV-infected LT patients. An investigation of Tregs may possibly help to distinguish recurrent HCV from graft rejection. Further functional studies are needed to define the role of Tregs in determining the balance between antiviral and allogenic immunity.

Co-immunization of mice with a retroviral DNA vaccine and GITRL-encoding plasmid augments vaccine-induced protection against retrovirus infection

After more than 30 years of research a HIV vaccine is still not at hand. DNA vectors expressing viral antigens are very safe vaccines, but so far they have not been efficient enough to induced broad protective immunity against retroviruses. One strategy to enhance the efficiency of DNA vaccines is to augment effector T-cell priming against viral components by manipulating regulatory T-cell functions (Treg). Glucocorticoid-induced tumor necrosis factor receptor (GITR) is a molecule that is constitutively expressed on CD4(+) Treg cells, and antibodies or natural ligands binding this molecule can impair Treg cell suppression. Here we demonstrate using the retroviral Friend virus (FV) mouse model, that co-immunization of FV antigens along with GITR-ligand (GITRL) encoding plasmids protected mice efficiently against a FV challenge. On the other hand, treatment of DNA-vaccinated mice with alpha-GITR antibody did not improve vaccine-induced protection at all. Thus, for an effective priming of immunity against FV, GITRL and viral antigens might have to be expressed within the same local environment. The data suggest that limitations in DNA vaccination can be overcome by co-expressing co-stimulatory molecules that potentially manipulate the function of Treg cells during priming of anti-retroviral immunity.

CpG oligodeoxynucleotides allow for effective adoptive T-cell therapy in chronic retroviral infection

Adoptive T-cell therapy in cancer or chronic viral infections is often impeded by the development of functional impairment of the transferred cells. To overcome this therapeutic limitation we combined adoptive transfer of naive, virus-specific CD8+ T cells with immunostimulative CpG oligodeoxynucleotides (ODNs) in mice chronically infected with the Friend retrovirus. The CpG-ODN co-injection prevented the T cells from developing functional defects in IFNgamma and granzyme production and degranulation of cytotoxic molecules. Thus, the transferred T cells were able to reduce chronic viral loads when combined with CpG-ODNs. This strategy provides a new approach for developing successful adoptive T-cell therapy against chronic infections.

Kinetics of CD8+ effector T cell responses and induced CD4+ regulatory T cell responses during Friend retrovirus infection

Cytolytic CD8+ T cells are critical for the control of acute Friend virus (FV) infection yet they fail to completely eliminate the virus during chronic infection because they are functionally impaired by regulatory T cells (Treg). We performed a kinetic analysis of T cell responses during FV infection to determine when dysfunction of CD8+ T cells and suppressive activity of CD4+ regulatory T cells develops. At 1 week post infection, virus-specific CD8+ T cells with effector phenotype and cytolytic potential expanded. Peak expansion was found at 12 days post infection, correlating with peak viral loads. After 2 weeks when viral loads dropped, numbers of activated CD8+ T cells started to decline. However, a population of virus-specific CD8+ T cells with effector phenotype was still detectable subsequently, but these cells had lost their ability to produce granzymes and to degranulate cytotoxic molecules. Contemporaneous with the development of CD8+ T cell dysfunction, different CD4+ T cell populations expressing cell surface markers for Treg and the Treg-associated transcription factor Foxp3 expanded. Transfer as well as depletion experiments indicated that regulatory CD4+ cells developed during the second week of FV infection and subsequently suppressed CD8+ T cell functions, which was associated with impaired virus clearance.

Effective treatment of retrovirus-induced suppression of antibody responses with CpG oligodeoxynucleotides

Most retroviruses induce severe immunosuppression during acute infection. We have used the Friend retrovirus mouse model to demonstrate that immunostimulatory B-type CpG oligodeoxynucleotides (ODN) have a protective effect against retrovirus-induced suppression of antibody responses to potent B-cell antigens. CD8+ T cells were critical for effective treatment with CpG-ODN, since in vivo depletion of these cells from treated mice impaired protection from retrovirus-induced immunosuppression. Protection also required IFN-gamma, as neutralization of this cytokine abolished the therapeutic effect of CpG-ODN. These findings may have implications for the treatment of immunosuppressive virus infections.