Niamh Nolan

Resident human hepatitis lymphocytes are phenotypically different from circulating lymphocytes

BACKGROUND/AIMS Murine and human studies have documented the existence of subpopulations of lymphocytes in particular tissues that differ phenotypically and functionally from those in peripheral blood and may mature locally. Since little is known about lymphocyte subpopulations in the normal human liver, we have analysed the surface phenotypes of lymphocytes isolated from liver specimens taken from 15 donors at the time of liver transplantation, and compared these with those of peripheral blood lymphocytes. METHODS Hepatic lymphocytes were prepared by mechanical dissociation and enzymatic digestion of liver tissue. The cells were stained with a panel of monoclonal antibodies (CD3, CD4, CD8, CD19, CD56, gammadeltaTCR, alphabetaTCR, CD8alpha-chain, CD8alphabeta dimer), and analysed by flow cytometry. In situ characterisation of hepatic lymphocytes was by haematoxylin and eosin staining of fixed liver sections and by immunohistochemical staining for common leukocyte antigen and CD3. RESULTS Significant numbers of hepatic T lymphocytes were localised to the portal tracts and parenchyma of normal liver specimens. Flow cytometry revealed that the CD4/CD8 ratio (1:3.5) was consistently reversed compared with that in peripheral blood (2:1). Other lymphocyte populations identified include double positive CD3+CD4+CD8+ cells which accounted for a mean of 5.5% (range 3-11.6%) of hepatic CD3+ cells compared with 1.3% in blood (range 0.7-3.6%; p < 0.007), and double negative CD3+ CD4-8- cells (14.5%; range 2.7-29% compared with 5.0%; range 2.1-10.8%, p < 0.02). Over 15% (range 6.8-34%) of all hepatic CD3+ cells expressed a gammadeltaTCR compared to 2.7% (range 0.9-4.7%) of CD3+ peripheral blood lymphocytes (p < 0.004) and almost 50% of these coexpressed CD8. The CD8 alpha-chain was expressed without the beta-chain (CD8alpha+beta-) by 15.4% (range 4-29.1%) of hepatic T cells, but this phenotype was undetectable among peripheral blood lymphocytes (p < 0.009). Cells expressing both the T cell marker CD3 and the natural killer cell marker CD56 constituted 31.6% (range 14-54%) of all hepatic CD3+ lymphocytes but were rarely present amongst peripheral blood lymphocytes (0-6%; p < 0.0001). CONCLUSIONS These data are the first to describe and quantify unconventional T lymphocyte subpopulations in the normal adult human liver which may have specialised functions in regional immune responses and which may differentiate locally. These findings have important implications for our understanding of hepatic immunoregulation and the pathogenic mechanisms involved in viral and immune-mediated liver disease and allograft rejection.

Distinct MHC class I and II alleles are associated with hepatitis C viral clearance, originating from a single source

The role of cytotoxic T lymphocyte responses, restricted by human leukocyte antigen (HLA) class I alleles, is recognized as highly significant in the successful clearance of hepatitis C virus (HCV). The frequency of class I alleles in females inoculated with HCV genotype 1b from a single source was examined for an association with outcome. Class I typing was performed using polymerase chain reaction sequence‐specific primers in 227 female subjects: 141 had chronic infection and 86 had viral clearance. Statistical analysis included χ2 testing and multiple logistic regression analysis. A*03, B*27, and Cw*01 occurred more frequently in those with viral clearance (39.5%, 14%, and 9.3%, respectively) compared with those with chronic infection (19.1%, 2.1%, and 1.4%, respectively; P ≤ .005). B*08 occurred more often in those with chronic infection compared with viral clearance (39.7% vs. 19.8%; P = .002). In combination with previously reported class II allele associations, over 75% that successfully eliminate HCV carry either A*03, DRB1*0101, or *0401, compared with only 37% of those with chronic infection (P < .0001). The haplotypes A*03‐B*07‐DRB1*15‐DQB1*0602 and A*02‐B*27‐Cw*01‐DRB1*0101‐DQB1*0501 are associated with viral clearance (P = .004 and .01, respectively). By multiple logistic regression analysis, the alleles A*03, B*27, DRB1*0101, *0401, and *15 are associated with viral clearance, and B*27 has the strongest association (odds ratio [OR] 7.99). The haplotype A*01‐B*08‐Cw*07‐DRB1*03011‐DQB1*0201 is associated with chronic infection (P = .002), being independent for DQB1*0201 (OR 0.27). In conclusion, certain class I alleles are associated with outcome in this homogenous cohort. More significantly, either HLA‐A*03, ‐DRB1*0101, or ‐*0401 are carried by an overwhelming majority of those subjects who successfully clear HCV. (HEPATOLOGY 2004;40:108–114.)

The Relationship of Omental and Subcutaneous Adipocyte Size to Metabolic Disease in Severe Obesity

Objective Several studies have reported the existence of a subgroup of obese individuals with normal metabolic profiles. It remains unclear what factors are responsible for this phenomenon. We proposed that adipocyte size might be a key factor in the protection of metabolically healthy obese (MHO) individuals from the adverse effects of obesity. Subjects Thirty-five patients undergoing bariatric surgery were classified as MHO (n = 15) or metabolically unhealthy obese (MUO, n = 20) according to cut-off points adapted from the International Diabetes Federation definition of the metabolic syndrome. Median body mass index (BMI) was 48 (range 40–71). Results There was a moderate correlation between omental adipocyte size and subcutaneous adipocyte size (r = 0.59, p<0.05). The MHO group had significantly lower mean omental adipocyte size (80.9±10.9 µm) when compared with metabolically unhealthy patients (100.0±7.6 µm, p<0.0001). Mean subcutaneous adipocyte size was similar between the two groups (104.1±8.5 µm versus 107.9±7.1 µm). Omental, but not subcutaneous adipocyte size, correlated with the degree of insulin resistance as measured by HOMA-IR (r = 0.73, p<0.0005), as well as other metabolic parameters including triglyceride/HDL-cholesterol ratio and HbA1c. Twenty-eight patients consented to liver biopsy. Of these, 46% had steatohepatitis and fibrosis. Fifty percent (including all the MHO patients) had steatosis only. Both omental and subcutaneous adipocyte size were significantly associated with the degree of steatosis (r = 0.66, p<0.0001 and r = 0.63, p<0.005 respectively). However, only omental adipocyte size was an independent predictor of the presence or absence of fibrosis. Conclusion Metabolically healthy individuals are a distinct subgroup of the severely obese. Both subcutaneous and omental adipocyte size correlated positively with the degree of fatty liver, but only omental adipocyte size was related to metabolic health, and possibly progression from hepatic steatosis to fibrosis.

Decrease in hepatic CD56+ T cells and Vα24+ natural killer T cells in chronic hepatitis C viral infection

BACKGROUND/AIMS The intrahepatic immune system is likely to play a key role in determining the outcome of hepatitis C virus (HCV) infection. The hepatic lymphocyte repertoire is characterised by high CD8/CD4 T cell ratios and large numbers of gamma delta T cells, natural killer (NK) cells, NK T cells and NK receptor-positive T cells. It is not known which of these populations contribute to immunity against HCV or immune pathology. METHODS To explore the relative contributions of lymphocyte subpopulations, we have compared the intrahepatic lymphocyte repertoires and cytokine expression in 13 patients with mild chronic hepatitis C infection, 14 with end-stage hepatitis C cirrhosis and five histologically normal livers by flow cytometry and immunohistochemistry. RESULTS CD4(+) T cells bearing alpha beta T cell receptors (TCR) were significantly expanded in livers with chronic HCV infection while CD56(+) alpha beta T cells and V alpha 24 TCR-positive T cells were significantly depleted. Expanded CD4(+)T cells were predominantly Th1 cells, producing interferon-gamma but not interleukin-4. CONCLUSIONS Failure to resolve HCV infection may be due to deficient innate and/or memory immune responses, while Th1 cells may mediate immune pathology.

Expansion of innate CD5pos B cells expressing high levels of CD81 in hepatitis C virus infected liver.

BACKGROUND/AIMS Association of hepatitis C virus (HCV) with increased autoantibodies, mixed cryoglobulinaemia, non-Hodgkins B-cell lymphoma and increased peripheral innate (CD5(pos)) B cells suggests a role for B-lymphocytes in the pathogenesis of HCV-infection. METHODS Flow cytometry was used to estimate CD5(pos) B cell levels and CD81 co-expression in chronic HCV infection. Viral load was assessed using PCR. RESULTS We demonstrate expansion of innate B cells in HCV-infected liver from patients with fibrosis score less than stage II (39%, % of total B cells, P=0.002) and end stage HCV cirrhosis (20%, P<0.05) compared with normal liver (8%). Expression of CD81, a signal transducing molecule and putative HCV receptor, was significantly increased on peripheral blood CD5(pos) B cells compared with conventional B cells (P=0.0001). Higher levels of CD81 on CD5(pos) B cells were more dramatic in the liver of HCV-infected individuals. However, no significant difference was observed in the viral load of CD5(pos)CD81(High) B cells and CD5(neg)CD81(Low) B cells. CONCLUSIONS Increased expression of CD81 on innate B cells, a population that is expanded in the livers and peripheral blood of chronic HCV-infected patients, suggests a role in viral specific activation and clonal proliferation in chronic HCV infection.

The MHC is a major determinant of viral status, but not fibrotic stage, in individuals infected with hepatitis C

BACKGROUND & AIMS In hepatitis C infection, several studies have examined the role of the major histocompatibility complex (MHC) in determining outcome, with variable results. To clarify the importance of MHC, we examined class II DR and DQ antigens in a homogenous cohort of women exposed to hepatitis C genotype 1b from a single inoculum. METHODS Of 243 participants, 95 had spontaneous viral clearance and 148 are chronically infected. The frequencies of HLA class II DR and DQ antigens were compared between the 2 groups and between liver biopsy findings of 145 chronically infected subjects. RESULTS DRB1*0101 and DQB1*0501 alleles were more frequent in subjects who sustained viral clearance than in chronically infected subjects (32.3% and 36.8% vs. 8.8% and 14.2%, respectively; P = 0.002). DRB1*03011 and DQB1*0201 occurred more frequently in chronically infected subjects than in those who cleared the virus (41.5% and 42.6% vs. 16.7% and 15.8%, respectively; P = 0.001). Both DRB1*03011 and DQB1*0201 were significantly less frequent in those with higher inflammatory scores on liver biopsy. CONCLUSIONS We show that in a homogenous cohort of women infected with the same hepatitis C virus, several HLA antigens are associated with either viral clearance or persistence. This suggests a strong role for host immunogenetic factors in determining outcome in hepatitis C infection.

Modern management of pyogenic hepatic abscess: a case series and review of the literature

BackgroundPyogenic hepatic abscesses are relatively rare, though untreated are uniformly fatal. A recent paradigm shift in the management of liver abscesses, facilitated by advances in diagnostic and interventional radiology, has decreased mortality rates. The aim of this study was to review our experience in managing pyogenic liver abscess, review the literature in this field, and propose guidelines to aid in the current management of this complex disease.MethodsDemographic and clinical details of all patients admitted to a single institution with liver abscess over a 5 year period were reviewed. Clinical presentation, aetiology, diagnostic work-up, treatment, morbidity and mortality data were collated.ResultsOver a 5 year period 11 patients presented to a single institution with pyogenic hepatic abscess (55% males, mean age 60.3 years). Common clinical features at presentation were non-specific constitutional symptoms and signs. Aetiology was predominantly gallstones (45%) or diverticular disease (27%). In addition to empiric antimicrobial therapy, all patients underwent radiologically guided percutaneous drainage of the liver abscess at diagnosis and only 2 patients required surgical intervention, including one 16-year old female who underwent hemi-hepatectomy for a complex and rare Actinomycotic abscess. There were no mortalities after minimum follow-up of one year.ConclusionsPyogenic liver abscesses are uncommon, and mortality has decreased over the last two decades. Antimicrobial therapy and radiological intervention form the mainstay of modern treatment. Surgical intervention should be considered for patients with large, complex, septated or multiple abscesses, underlying disease or in whom percutaneous drainage has failed.

Effect of Chronic Hepatitis C Virus Infection on Bone Disease in Postmenopausal Women

BACKGROUND & AIMS Limited data are available on the contribution of chronic HCV infection to the development of bone disease in postmenopausal women. We studied whether women who acquired HCV infection through administration of HCV genotype 1b-contaminated anti-D immunoglobulin from a single source had decreased bone mineral density (BMD) or altered levels of bone turnover markers (BTMs), compared with women who spontaneously resolved infection or age-matched healthy controls. METHODS From a cohort of postmenopausal Irish women, we compared BMD, determined by dual-energy x-ray absorptiometry, and a panel of BTMs in 20 women chronically infected with HCV (PCR(+)), 21 women who had spontaneously resolved infection (PCR(-)), and 23 age-matched healthy controls. RESULTS Levels of BTMs and BMD were similar in PCR(+) and PCR(-) women and healthy age-matched controls. However, there was an increased frequency of fractures in PCR(+) (n = 6) compared with PCR(-) women (n = 0, P = .007). PCR(+) women with fractures were postmenopausal for a longer time (median, 15.5, range, 5-20 years vs 4.5, range, 1-20 years in PCR(+) women without fractures; P = .033), had lower BMD at the hip (0.79, range, 0.77-0.9 g/cm(2) vs 0.96, range, 0.81-1.10 g/cm(2); P = .007), and had a lower body mass index (23.7, range 21.2-28.5 kg/m(2) vs 25.6, range 22.1-36.6 kg/m(2); P = .035). There was no difference in liver disease severity or BTMs in PCR(+) women with or without fractures. CONCLUSIONS Chronic HCV infection did not lead to discernable metabolic bone disease in postmenopausal women, but it might be a risk factor for bone fractures, so preventive measures should be introduced. To view this articles video abstract, go to the AGAs YouTube Channel.

Variant in CD209 promoter is associated with severity of liver disease in chronic hepatitis C virus infection

CD209, a c-type lectin expressed by dendritic cells (DCs), acts as a pathogen recognition receptor. A single nucleotide polymorphism (SNP) in the promoter region of CD209 (-336 A/G; rs4804803) affects transcription and is associated with the severity of tuberculosis and dengue fever. Because CD209 binds hepatitis C virus (HCV) glycoprotein-E2, we investigated this SNP in the context of chronic HCV infection. A total of 131 Irish women who had received HCV-contaminated anti-D-immunoglobulin and 79 healthy control subjects were genotyped. We found no association between rs4804803 and the risk of HCV chronicity. However, of those with chronic infection, possession of at least one g-allele was associated with more advanced liver disease, with significantly higher liver fibrosis scores and levels of alanine transaminase (ALT) observed. We conclude that rs4804803, an SNP in the CD209 promoter, contributes to severity of liver disease in chronic HCV infection.

Orthotopic liver transplantation for veno-occlusive disease complicating autologous bone marrow transplantation.

BACKGROUND Veno-occlusive disease of the liver is a serious and often life-threatening complication after bone marrow transplantation. Although risk factors for the development of veno-occlusive disease have been postulated, there is no precise method for accurately identifying those patients who are at risk and for whom early intervention and treatment would have maximum potential benefit. Liver transplantation has been advocated as a treatment for veno-occlusive disease in selected patients. METHODS In this report, we describe a patient who underwent liver transplantation for life-threatening veno-occlusive disease after autologous bone marrow transplantation for acute lymphoblastic leukemia. RESULTS Liver engraftment was achieved, but the patient developed Pneumocystis pneumonia, which failed to respond to pentamidine. The patient died 6 months after liver transplantation. CONCLUSIONS While acknowledging the limited experience of orthotropic liver transplantation in this patient population, we suggest its consideration as a feasible, potentially beneficial treatment option in patients with severe veno-occlusive disease after bone marrow transplantation.