Expansion of dysfunctional CD56-CD16+ NK cells in chronic hepatitis B patients.

BACKGROUND & AIMS: Natural killer (NK) cells are primary innate effector cells that play an important role in the control of human viral infections. During chronic viral infection, NK cells undergo significant changes in phenotype, function and subset distribution, including the appearance of CD56-CD16+ (CD56-) NK cells, previously identified in chronic human immunodeficiency virus (HIV) and hepatitis C virus infection. However, the presence of CD56- NK cells in the pathogenesis of chronic hepatitis B (CHB) remains unknown. METHODS: Phenotype and function of CD56- NK cells from patients with CHB (n = 28) were assessed using flow cytometry and in vitro stimulation with HBV antigen. RESULTS: CHB patients had a higher frequency of CD56- NK cells compared to healthy controls in peripheral blood (6.2% vs 1.4%, P < .0001). Compared to CD56+ NK cells, CD56- NK cells had increased expression of inhibitory receptors, and reduced expression of activating receptors, as measured by MFI and qPCR. CD56- NK cells were less responsive to target cell and cytokine stimulation compared to their CD56+ counterparts. In addition, CD56- NK cells demonstrated defective dendritic cells (DCs) interactions resulting in reduced DCs maturation, lower expression of NK CD69 and impaired capacity of NK cells to eliminate immature DCs in co-culture studies. Finally, frequency of CD56- NK cells was positively correlated with serum HBV DNA levels. CONCLUSION: Chronic HBV infection induces the expansion of highly dysfunctional of CD56- NK cells that likely contribute to inefficient innate and adaptive antiviral immune response in chronic HBV infection.

HBV vaccination and HBV infection induces HBV-specific natural killer cell memory.

OBJECTIVE: Vaccination against hepatitis B virus (HBV) confers protection from subsequent infection through immunological memory that is traditionally considered the domain of the adaptive immune system. This view has been challenged following the identification of antigen-specific memory natural killer cells (mNKs) in mice and non-human primates. While the presence of mNKs has been suggested in humans based on the expansion of NK cells following pathogen exposure, evidence regarding antigen-specificity is lacking. Here, we demonstrate the existence of HBV-specific mNKs in humans after vaccination and in chronic HBV infection. DESIGN: NK cell responses were evaluated by flow cytometry and ELISA following challenge with HBV antigens in HBV vaccinated, non-vaccinated and chronic HBV-infected individuals. RESULTS: NK cells from vaccinated subjects demonstrated higher cytotoxic and proliferative responses against autologous hepatitis B surface antigen (HBsAg)-pulsed monocyte-derived dendritic cells (moDCs) compared with unvaccinated subjects. Moreover, NK cell lysis of HBsAg-pulsed moDCs was significantly higher than that of hepatitis B core antigen (HBcAg)-pulsed moDCs (non-vaccine antigen) or tumour necrosis factor α-activated moDCs in a NKG2D-dependent manner. The mNKs response was mediated by CD56dim NK cells coexpressing CD57, CD69 and KLRG1. Further, mNKs from chronic hepatitis B patients exhibited greater degranulation against HBcAg-pulsed moDCs compared with unvaccinated or vaccinated patients. Notably, mNK activity was negatively correlated with HBV DNA levels. CONCLUSIONS: Our data support the presence of a mature mNKs following HBV antigen exposure either through vaccination or infection. Harnessing these antigen specific, functionally active mNKs provides an opportunity to develop novel treatments targeting HBV in chronic infection.

Hepatitis C Virus (HCV) Eradication With Interferon-Free Direct-Acting Antiviral-Based Therapy Results in KLRG1+ HCV-Specific Memory Natural Killer Cells.

Direct acting antiviral therapies rapidly clear chronic hepatitis C virus (HCV) infection and restore natural killer (NK) cell function. We investigated NK-cell memory formation following HCV clearance by examining NK-cell phenotype and responses from control and chronic HCV patients before and after therapy following sustained virologic response at 12 weeks post therapy (SVR12). NK-cell phenotype at SVR12 differed significantly from paired pretreatment samples, with an increase in maturation markers CD16, CD57, and KLRG1. HCV patients possessed stronger cytotoxic responses against HCV-infected cells as compared to healthy controls; a response that further increased following SVR12. The antigen-specific response was mediated by KLRG1+ NK cells, as demonstrated by increased degranulation and proliferation in response to HCV antigen only. Our data suggest that KLRG1+ HCV-specific memory NK cells develop following viral infection, providing insight into their role in HCV clearance and relevance with regard to vaccine design.

KLRG1+ natural killer cells exert a novel antifibrotic function in chronic hepatitis B.

BACKGROUND & AIMS: Natural killer (NK) cells are known to exert strong antiviral activity. Killer cell lectin-like receptor subfamily G member 1 (KLRG1) is expressed by terminally differentiated NK cells and KLRG1-expressing lymphocytes are known to expand following chronic viral infections. We aimed to elucidate the previously unknown role of KLRG1 in the pathogenesis of chronic hepatitis B (CHB). METHODS: KLRG1+ NK cells were taken from the blood and liver of healthy individuals and patients with CHB. The phenotype and function of these cells was assessed using flow cytometry and in vitro stimulation. RESULTS: Patients with CHB had a higher frequency of KLRG1+ NK cells compared to healthy controls (blood 13.4 vs. 2.3%, p <0.0001 and liver 23.4 vs. 2.6%, p <0.01). KLRG1+ NK cells were less responsive to K562 and cytokine stimulation, but demonstrated enhanced cytotoxicity (9.0 vs. 4.8%, p <0.05) and IFN-γ release (8.0 vs. 1.5%, p <0.05) via antibody dependent cellular cytotoxicity compared to their KLRG1- counterparts. KLRG1+ NK cells possessed a mature phenotype, demonstrating stronger cytolytic activity and IFN-γ secretion against hepatic stellate cells (HSCs) than KLRG1- NK cells. Moreover, KLRG1+ NK cells more effectively induced primary HSC apoptosis in a TRAIL-dependent manner. Increased KLRG1+ NK cell frequency in the liver and blood was associated with lower fibrosis stage (F0/F1) in patients with CHB. Finally, the expression of CD44, degranulation and IFN-γ production were all increased in KLRG1+ NK cells following stimulation with osteopontin, the CD44 ligand, suggesting that HSC-derived osteopontin may cause KLRG1+ NK cell activation. CONCLUSIONS: KLRG1+ NK cells likely play an antifibrotic role during the natural course of CHB infection. Harnessing this antifibrotic function may provide a novel therapeutic approach to treat liver fibrosis in patients with CHB. LAY SUMMARY: Individuals that are chronically infected with hepatitis B virus (HBV) possess an increased number of immune cells, called natural killer (NK) cells expressing the surface marker KLRG1 in the blood and liver. Here, we demonstrate that these specific NK cells are able to kill activated stellate cells in the liver. Because activated stellate cells contribute to liver scarring, i.e. fibrosis, and subsequent liver dysfunction in individuals with chronic HBV infection, KLRG1+ NK cells are a novel immune cell type that can limit liver scarring.

Improved prediction of fibrosis in chronic hepatitis C using measures of insulin resistance in a probability index.

We sought to develop a clinically useful index comprising standard and physiologically relevant variables to predict the probability of significant hepatic fibrosis in subjects with chronic hepatitis C virus (HCV) infection. Fibrosis was graded as mild (stages F0 or F1) or significant (stages F2-F4). Thirty-five clinical and laboratory parameters were analyzed initially in 176 patients with detectable HCV RNA to derive a fibrosis probability index (FPI) to predict significant fibrosis. This index then was validated in a second group of 126 subjects. Among 18 variables associated with severe fibrosis on univariate analysis, multiple logistic regression analysis identified age, aspartate aminotransferase (AST), total cholesterol level, insulin resistance (by homeostasis model), and past alcohol intake as independent predictors of significant fibrosis. The area under the receiver operating characteristic (ROC) curves was 0.84 for the initial cohort and 0.77 for the validation cohort. In the initial cohort, the sensitivity of the FPI based on these five predictors was 96%, and the negative predictive value was 93% at a score of >/=0.2. At scores >/=0.8, the FPI was 94% specific and had a positive predictive value of 87%. In conclusion, an FPI using routinely assessed markers and incorporating a measure of insulin resistance can reliably predict the probability of significant hepatic fibrosis in most patients with chronic HCV infection. Such an index should prove useful to guide decision making regarding the need for liver biopsy, and potentially for avoiding or deferring biopsy in a large proportion of patients with mild liver disease.

Effects of interferon treatment response on liver complications of chronic hepatitis C: 9-year follow-up study.

OBJECTIVES: Fibrotic severity, biochemical indices of poor liver function, and sporadic transmission are independent predictors of liver complications among people with chronic hepatitis C. After accounting for these factors, we tested whether interferon treatment or the treatment response reduces the rate of liver cancer, liver-related death or transplantation, and other liver complications during extended follow-up. METHODS: Liver clinic cohort of 455 patients with histologically proven chronic hepatitis C was followed prospectively for median 9 yr (IQ 6, 11 yr); 384 received interferon, 343 completed a treatment course. Liver complications were assessed in relation to treatment and treatment response in univariate and multivariate models, and survival to onset of liver-related complications was determined. RESULTS: The annual incidence of total liver complications was 1.5% in treated and 2.9% in untreated patients and appeared quasilinear throughout 9-yr follow-up. Interferon treatment did not influence the rate of liver complications. However, the rate of complications increased exponentially with transition of the treatment response from sustained viral response (SVR), through response-relapse to nonresponse (or no treatment). By univariate analysis, response to interferon treatment was a significant predictor of complications. After adjustment for fibrosis score, serum albumin concentration and mode of transmission in a multivariate model, treatment response just failed to reach significance (p= 0.058) as a predictor of outcome. CONCLUSIONS: Response to antiviral therapy, and particularly SVR, appears to reduce liver complications in chronic hepatitis C. However, in the absence of an antiviral treatment response, a course of interferon does not reduce risks of liver cancer or liver failure.

Transjugular liver biopsy effecting changes in clinical management.

Although transjugular liver biopsies are frequently performed in patients with impaired blood coagulation, their impact on effecting changes in clinical management has not been assessed. We reviewed our experience with 43 consecutive transjugular liver biopsies performed over 3 years (1998-2000) at Westmead Hospital, Sydney, Australia. The technical success, procedural complication rates and subsequent management of these patients were ascertained from the medical case records. Forty-two (28 men) patients were studied. The indications for liver biopsy were as follows: assessment of hepatitis/cirrhosis status (n = 21), evaluation of liver dysfunction following bone marrow transplantation (n = 19) and miscellaneous (n = 2). All liver biopsies were performed with a Cook 20-G transjugular cutting needle device. Adequate histological samples were obtained in 42 (98%) of the 43 biopsies performed. The pre-biopsy diagnoses were confirmed by histology in 28 cases (65%). A change in clinical diagnosis was observed in 12 (28%) patients, and there were changes to subsequent management in all 12 patients. Four patients developed procedural complications, including small neck haematomas in two patients and a self-limiting biliary fistula in one. The only major complication was an extracapsular bleed from a hepatic laceration. This patient required emergency surgery but recovered. Transjugular liver biopsies can be effectively and safely performed in high-risk patients with impaired coagulation. They aid accurate histological appraisal of liver dysfunction in these patients and influence clinical decision-making.

Changes in antipyrine clearance and platelet count, but not conventional liver tests, correlate with fibrotic change in chronic hepatitis C: value for predicting fibrotic progression.

OBJECTIVE: We tested whether fibrotic progression in chronic hepatitis C could be predicted by liver tests, antipyrine clearance, or platelet count. METHODS: In 58 patients (6 untreated, 52 interferon-treated), a second liver biopsy was taken median 4.5 yr after first histologic diagnosis. We used receiver operating characteristic curves to determine whether changes in conventional liver tests, antipyrine clearance, or platelet count were predictive of altered hepatic fibrosis score. RESULTS: Apart from a weak association with change in ALT, conventional liver tests (albumin, bilirubin, prothrombin time) failed to correlate with changes (Delta) in hepatic fibrosis, but there were significant correlations between deltaantipyrine clearance or deltaplatelet count and deltafibrosis score (p < 0.01). As indicated by areas under the receiver operating characteristic curves, the diagnostic accuracy of deltaantipyrine clearance for fibrotic progression was 68%; for Deltaplatelet count it was 80%. With defined cut-off values (-0.05 ml/min/kg for deltaantipyrine clearance; -41 x 10(9)/L for deltaplatelet count), the negative predictive values for fibrotic progression were 85% with antipyrine clearance and 89% with platelet count. Corresponding positive predictive values were 48% and 91%, respectively. CONCLUSIONS: Changes in antipyrine clearance and platelet count are more sensitive than conventional tests for indicating fibrotic change in chronic hepatitis C. Both could be used to reliably identify those who do not have fibrotic progression, and platelet count also has a high positive predictive value for disease progression.

Effectiveness of interferon alfa-2b/ribavirin combination therapy for chronic hepatitis C in a clinic setting.

AIM: To determine effectiveness of treatment for hepatitis C outside clinical trials, by testing the hypothesis that apparent effectiveness and tolerability of interferon alfa-2b/ribavirin combination therapy would be less in a hospital liver clinic setting. DESIGN: Retrospective analysis of all patients in one centre commencing interferon alfa-2b/ribavirin therapy, but not in clinical trials, between 1998 and 2000. MAIN OUTCOME MEASURES: Effectiveness as sustained virological response (SVR); tolerability as premature discontinuation of treatment. RESULTS: The 121 patients had similar demographic and viral characteristics as those in Australian trials (age, 44 +/- 10 years; males, 66%; genotype 1, 44%; genotype 3, 36%), but 38% had advanced fibrosis, including 17% with cirrhosis. Sixty (50%) were previously untreated, 38 (31%) had relapsed after initial response (response relapse) and 23 (19%) were non-responders to interferon monotherapy. Sustained viral response (SVR) was achieved in 53% of patients overall: 47% of patients with genotype 1 HCV, 71% of patients with genotype 3. For patients with genotype 1 HCV, SVR was 43% in those previously untreated, 63% in response relapsers, and 38% in non-responders. Corresponding SVRs for genotype 3 were 65%, 87% and 33%. These results are similar to those obtained in published trials. Only 7% of our patients discontinued treatment because of adverse effects, fewer than reported in most clinical trials. Dose reduction was required in 18% of patients. CONCLUSIONS: In a hospital clinic setting the effectiveness of interferon alfa-2b/ribavirin combination therapy appears equivalent to published results from clinical trials.

Genotype-specific mechanisms for hepatic steatosis in chronic hepatitis C infection.

BACKGROUND: Hepatic steatosis is common in hepatitis C, but the relative importance of host and viral factors is controversial. In the present prospective study, we examined metabolic factors associated with non-alcoholic fatty liver and viral genotype as predictors of steatosis and fibrosis in chronic hepatitis C infection. METHODS: In 124 chronic hepatitis C patients, the association between liver histology and the following was investigated: demographic and anthropometric data, alcohol intake, alanine aminotransferase (ALT), total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, triglyceride, transferrin saturation, ferritin, insulin, c-peptide, glucose and insulin resistance (homeostasis model). RESULTS: By multivariate analysis, genotype 3 was associated with increased steatosis grade (P = 0.02). There were significant pairwise interactions between genotype 3 status and total cholesterol (P = 0.01), current alcohol intake (P = 0.04) and serum ALT (P = 0.01). This showed that the etiology of steatosis was different in patients with genotype 3 and those with non-genotype 3 chronic hepatitis C infection. In genotype 3 patients, the degree of steatosis was inversely associated with serum cholesterol (P = 0.005) and positively associated with serum triglyceride (P = 0.02). There was no association between body mass index (BMI) and the extent of steatosis. Among patients with other genotypes, the steatosis grade was strongly influenced by BMI (P < 0.0001) and serum ALT (P < 0.01). Independent predictors of fibrosis were age (P = 0.001), past alcohol intake (P = 0.04), ALT (P = 0.002), serum insulin (P = 0.001) and portal inflammation (P < 0.001). CONCLUSIONS: Hepatitis C genotype 3 may interfere with pathways of hepatic lipid metabolism, whereas increased BMI appears to be a more important pathogenic factor in other genotypes. Although steatosis and BMI were not associated with hepatic fibrosis, their relationship with serum insulin suggests that metabolic factors related to insulin action could influence fibrogenesis in hepatitis C.

Serum leptin in NASH correlates with hepatic steatosis but not fibrosis: a manifestation of lipotoxicity?

Nonalcoholic steatohepatitis (NASH) is a disorder characterized by hepatic steatosis, inflammation, and fibrosis. Leptin is an adipocyte-derived antiobesity hormone that in rodents prevents "lipotoxicity" by limiting triglyceride accumulation and also regulates matrix deposition (fibrosis) during wound healing. We therefore determined serum leptin levels in patients with NASH to determine whether relationships existed between leptin levels and severity of hepatic steatosis or fibrosis. We used a radioimmunoassay to determine serum [total] leptin concentrations in 27 men and 20 women with NASH and 47 controls matched for gender and body mass index (BMI; and partly for age). Serum leptin values were correlated with hepatic steatosis, fibrosis, and inflammation (each categorized semiquantitatively on liver histology), and with anthropometric indices, serum lipids, glucose, insulin, c-peptide, and alanine aminotransferase (ALT) levels. Compared with the controls, mean serum leptin levels were raised in both men and women with NASH (men 14 +/- 11 ng/mL vs. 7.2 +/- 4.1 ng/mL, P =.003; women 35 +/- 16 ng/mL vs. 15 +/- 8.2 ng/mL, P <.001). Leptin values correlated with serum c-peptide levels but not with BMI. In a multivariate analysis, serum leptin (P =.027), serum c-peptide (P =.001), and age (P =.027) were selected as independent predictors of the severity of hepatic steatosis. However, serum leptin was not an independent predictor of hepatic inflammation or fibrotic severity. In conclusion, hyperleptinemia occurs in NASH and is not explained simply by gender, obesity, or the presence of type 2 diabetes. Furthermore, leptin levels correlate directly with the severity of hepatic steatosis but not with inflammation or fibrosis. We propose that the relationship between leptin and steatosis reflects a pathogenic role of leptin in hepatic insulin resistance and/or a failure of the antisteatotic actions of leptin ("peripheral leptin resistance").

HFE mutations, hepatic iron, and fibrosis: ethnic-specific association of NASH with C282Y but not with fibrotic severity.

There is conflicting evidence regarding inheritance of hemochromatosis gene (HFE) mutations and influence of hepatic iron deposition as cofactors for development of fibrosis in patients with nonalcoholic steatohepatitis (NASH). We studied hepatic iron content (Perls' stain grade), frequency of HFE mutations, and serum iron indices in 93 patients with NASH from a multiethnic background; 59 (63%) were of Anglo-Celtic origin. Data on C282Y mutations were available for all 93 patients and on H63D for 69 patients. Respective controls were 206 (for C282Y, 141 [69%] of whom were Anglo-Celtic) and 180 (for H63D) blood donors. Hyperferritinemia was present in 38 patients (40%) with NASH, but transferrin saturation was increased (>55%) in only 5 (5%). Liver biopsy specimens showed advanced fibrosis in 31 (33%) (cirrhosis in 20%). Altogether, 9 biopsy specimens (10%) showed increased iron: 7 (8%) with grade 2 and 2 (2%) with grade 3 iron staining. Only 1 biopsy specimen with increased iron showed advanced fibrosis. The frequency of C282Y heterozygosity was increased in Anglo-Celtic patients with NASH compared with ethnic blood donor controls (22% vs. 9.2%; P =.035); there were no C282Y homozygotes in the NASH cohort. Although there was a trend toward higher serum ferritin levels among C282Y heterozygotes with NASH, there were no differences in histologic grades of steatosis, inflammation, or fibrosis between individuals with and without C282Y. The frequencies of compound C282Y/H63D heterozygotes (n = 1) or H63D heterozygotes (n = 10) were not increased in NASH. Multivariate analysis identified female sex, diabetes mellitus, and more severe liver inflammation but not HFE mutations, serum ferritin, iron saturation, or hepatic iron staining as independent predictors of hepatic fibrosis. In conclusion, hepatic iron is not a factor linked to hepatic fibrogenesis in patients with NASH. HFE mutations do not confer an additional risk of hepatic fibrosis in this disorder.

Changes in serum albumin during treatment of chronic hepatitis B with lamivudine: effects of response and emergence of drug resistance.

OBJECTIVES: In chronic hepatitis B patients treated with lamivudine, the incidence of drug resistance increases with the duration of therapy. The effect of drug resistance on hepatic synthetic function is not well defined. The aim of the present study was to assess the effect of lamivudine therapy on hepatic synthetic function in patients with moderately severe chronic hepatitis B and, particularly, to determine the effect of drug resistance. METHODS: Hepatic synthetic function was assessed using serial measurements of serum albumin in 38 patients (26 with cirrhosis) in an open-label treatment program. RESULTS: An initial antiviral response (hepatitis B virus [HBV] DNA undetectable by hybridization assay) occurred in all patients, and nine of 22 (41%) hepatitis B e antigen-positive cases underwent hepatitis B e antigen seroconversion. Among 29 patients with undetectable serum HBV DNA at the end of observation, the mean serum albumin concentration rose from 39.9 +/- 0.7 to 43.2 +/- 0.6 g/L, corresponding to a yearly increase of 1.85 g/L (p < 0.001). This was largely attributable to an increase among cirrhotic patients. Nine patients (24%) developed resistance to lamivudine, all after 12 months of treatment. Among them, the mean serum albumin concentration had increased from 39.6 +/- 1.2 to 42.9 +/- 0.8 g/L before resistance emerged, but then decreased to 39.3 +/- 1.7 g/L (p = 0.01) at the time of reappearance of HBV DNA. CONCLUSION: Suppression of viral replication by lamivudine improves hepatic synthetic function in chronic hepatitis B patients, but emergence of drug resistance is associated with a rapid decline in serum albumin, at least to pretreatment levels.

NASH and insulin resistance: Insulin hypersecretion and specific association with the insulin resistance syndrome.

Nonalcoholic steatohepatitis (NASH) is often linked with disorders that are clearly associated with insulin resistance (IR): obesity, type 2 diabetes mellitus, and hypertriglyceridemia. We tested the hypotheses that (1) IR is an essential requirement for the development of NASH and (2) a high association between IR and liver disease is relatively specific for NASH. We measured body mass index (BMI), waist/hip ratio, and fasting serum lipid, insulin, C-peptide, and glucose levels in 66 patients with NASH (21 with advanced fibrosis and 45 with mild fibrosis). IR was determined by the homeostasis model assessment (HOMA). We also determined the strength of the association of NASH with insulin resistance syndrome (IRS) as defined by World Health Organization criteria. To assess whether the finding of IR was relatively specific to NASH rather than simply to obesity or liver disease, we compared the results of a subset of 36 patients with less-severe NASH with 36 age- and sex-matched patients with chronic hepatitis C virus (HCV) of comparable fibrotic severity. IR was confirmed in 65 patients (98%) with NASH, and 55 (87%) fulfilled minimum criteria for IRS. IR was found in lean as well as in overweight and obese patients. The IR values and the prevalence of IRS (75% vs. 8.3%) were significantly higher in those with NASH than in comparable cases of HCV. Hyperinsulinemia was attributable to increased insulin secretion rather than decreased hepatic extraction. In conclusion, most patients with NASH have IRS, and there is a near-universal association between NASH and IR irrespective of obesity. IR is present in mild as well as advanced cases of NASH but is unusual in chronic HCV of similar fibrotic severity.