The impaired immune regulation of autoimmune hepatitis is linked to a defective galectin-9/tim-3 pathway

In autoimmune hepatitis (AIH), liver-damaging CD4 T cell responses are associated with defective CD4(pos) CD25(pos) regulatory T cells (T-regs). Galectin-9 (Gal9), a β-galactosidase-binding protein expressed by T-regs, is key to their function, inhibiting T helper 1 immune responses by binding T cell immunoglobulin and mucin domain 3 (Tim-3) on CD4 effector cells. We investigated whether impaired immunoregulation in AIH results from reduced expression of Gal9 in T-regs and/or Tim-3 on CD4 effector cells. Circulating Gal9(pos) CD4(pos) CD25(pos) and Tim-3(pos) CD4(pos) CD25(neg) T cell phenotype was assessed by flow cytometry in 75 AIH patients. To evaluate whether Tim-3 expression renders CD4(pos) CD25(neg) T cells amenable to T-reg control, purified CD4(pos) CD25(neg) Tim-3(pos) (Tim-3(pos)) and CD4(pos) CD25(neg) Tim-3(neg) (Tim-3(neg)) cells were cocultured with T-regs. To determine whether Gal9 expression is essential to function, T-regs were treated with small interfering RNA (siRNA) to repress Gal-9 translation; T-reg suppressor function was assessed by proliferation. In AIH, Tim-3(pos) cells within CD4(pos) CD25(neg) cells and their T-bet(pos) and RORC(pos) subsets were fewer and contained higher numbers of interferon-γ (IFNγ)(pos) and interleukin (IL)-17(pos) cells than healthy subjects (HS). In AIH and HS, Tim-3(pos) cells proliferated less vigorously and were more susceptible to T-reg control than Tim-3(neg) cells. In AIH, Gal9(pos) T-regs were fewer and contained less FOXP3(pos), IL-10(pos), and transforming growth factor β(pos) and more IFNγ(pos) and IL-17(pos) cells than HS. siRNA treatment of Gal-9(pos) T-regs drastically reduced T-reg ability to suppress CD4(pos) CD25(neg) and Tim-3(pos) cell proliferation in AIH and HS. Tim-3(pos) cell percentage correlated inversely with aminotransferase and CD25(neg) T-bet(pos) cell values.

CONCLUSION

Reduced levels of Tim-3 on CD4(pos) CD25(neg) effector cells and of Gal9 in T-regs contribute to impaired immunoregulation in AIH by rendering effector cells less prone to T-reg control and T-regs less capable of suppressing.

Inhibition of interleukin-17 promotes differentiation of CD25⁻ cells into stable T regulatory cells in patients with autoimmune hepatitis

BACKGROUND & AIMS

Patients with autoimmune hepatitis (AIH) have reduced numbers and function of CD4+CD25(high)FOXP3+ T regulatory cells (Tregs). Tregs can be generated from CD25⁻ (ngTreg) cells, which suppress the immune response less efficiently than Tregs. We investigated whether their differentiation into T-helper (Th)17 cells, an effector subset that has the same CD4+ progenitors as Tregs, accounts for the reduced suppressive functions of ngTregs. We investigated whether blocking interleukin (IL)-17 increased the immunosuppressive activity of Tregs.

METHODS

ngTregs were generated from 36 patients with AIH and 23 healthy subjects (controls). During Treg differentiation, expression of IL-17 was inhibited by physical removal of IL-17-secreting cells, exposure to recombinant transforming growth factor β or neutralizing antibodies against IL-6 and IL-1β (to promote differentiation of ngTregs vs Th17 cells), small inhibitory RNAs specific for the Th17 transcription factor RORC, or a combination of all these approaches.

RESULTS

ngTregs from patients with AIH contained greater proportions of IL-17+ and RORC+ cells than Tregs from controls. All approaches to inhibit IL-17 increased expression of FOXP3 by ngTregs and their suppressive functions. Inhibition of IL-17 led to development of ngTregs that were phenotypically stable and did not acquire proinflammatory properties after exposure to IL-6 and IL-1β.

CONCLUSIONS

Blocking Th17 allows ngTregs to differentiate into functionally stable immune inhibitory cells; this approach might be developed for therapy of patients with AIH.

Autoimmune hepatitis after liver transplantation

Liver transplantation is an effective treatment for patients with end-stage acute and chronic autoimmune hepatitis. However, despite the good outcomes reported, disease recurrence is relatively common in the allograft. In addition, autoimmunity and autoimmune liver disease can arise de novo after transplantation for non-autoimmune liver disorders. Little is known about the mechanisms by which autoimmune diseases develop after liver transplantation, but genetic factors, molecular mimicry, impaired regulatory T-cell responses, and exposures to new alloantigens might be involved. Regardless of the pathogenic mechanisms, it is important to remain aware of the existence of recurrent and de novo autoimmune hepatitis after liver transplantation; these disorders are similar to classic autoimmune hepatitis and are therefore not treated with standard antirejection strategies.

A clinical prediction rule and platelet count predict esophageal varices in children

BACKGROUND & AIMS

The validation of noninvasive tests to diagnose esophageal varices is a priority in children because repeated endoscopic evaluations are too invasive. We measured the ability of a previously developed noninvasive clinical prediction rule (CPR) to predict the presence of esophageal varices in children.

METHODS

We analyzed data from 108 children, younger than age 18, who received endoscopies at 8 centers, to assess portal hypertension from chronic liver disease or portal vein obstruction. Blood test and abdominal ultrasound scan results were obtained within 4 months of endoscopy. Grading of varices identified by endoscopy was confirmed by independent blinded review. Spleen size, based on data from the ultrasound scan, was expressed as a standard deviation score relative to normal values for age.

RESULTS

Of the children studied, 74 had esophageal varices (69%), including 35 with large varices (32%). The best noninvasive predictors of esophageal varices of any size were as follows: platelet:spleen size z-score ratio (area under the receiver operating characteristic curve [AUROC], 0.84; 95% confidence interval [CI] 0.75-0.93), CPR (AUROC, 0.80; 95% CI, 0.70-0.91), and platelet count (AUROC, 0.79; 95% CI, 0.69-0.90). The positive predictive values for the CPR and platelet count were 0.87 and 0.86, the negative predictive values were 0.64 and 0.63, the positive likelihood ratios were 3.06 and 2.76, and the negative likelihood ratios were 0.64 and 0.63, respectively. Based on positive and negative predictive values, the most accurate noninvasive tests were the CPR and platelet counts.

CONCLUSIONS

Noninvasive tests such as CPR and platelet count can assist in triaging children for endoscopy to identify esophageal varices.

Autoimmune liver diseases in children - what is different from adulthood?

Autoimmune liver disorders in childhood include autoimmune hepatitis, autoimmune sclerosing cholangitis and de novo autoimmune hepatitis after liver transplant. These inflammatory liver disorders are characterised histologically by interface hepatitis, biochemically by elevated transaminase levels and serologically by autoantibodies and increased levels of immunoglobulin G. Autoimmune hepatitis is particularly aggressive in children and progresses rapidly unless immunosuppressive treatment is started promptly. With appropriate treatment 80% of patients achieve remission and long-term survival. Autoimmune sclerosing cholangitis responds to the same treatment used for autoimmune hepatitis in regards to parenchymal inflammation, but bile duct disease progresses in about 50% of cases, leading to a worse prognosis and higher transplantation requirement; it has a high recurrence rate post-liver transplant. De novo autoimmune hepatitis after liver transplant affects children transplanted for non-autoimmune conditions and responds well to the same treatment schedule used for autoimmune hepatitis, but not to the schedule used for acute rejection.

Pathogenesis of autoimmune hepatitis

The mechanisms underlying the pathogenesis of autoimmune hepatitis are not fully understood, though there is growing evidence that genetic predisposition, molecular mimicry and/or impairment of regulatory T-cells are involved in the initiation and perpetuation of the autoimmune liver attack. The histological picture of interface hepatitis, characterized by a dense portal mononuclear cell infiltrate, was the first to suggest an autoaggressive cellular immune attack in the pathogenesis of this condition. Liver damage is likely to be orchestrated by CD4(pos) T-cells recognizing an autoantigenic liver peptide. For autoimmunity to arise, the peptide must be presented by antigen-presenting cells to naïve CD4(pos) T-helper (Th0) cells. Once activated, Th0-cells can differentiate into Th1-, Th2-, or Th17-cells, initiating a cascade of immune reactions that are determined by the cytokines they produce. Autoantigen recognition and the above effector mechanisms are opposed by regulatory T-cells, a cell subset numerically and functionally impaired in autoimmune hepatitis.

Sirolimus as renal and immunological rescue agent in pediatric liver transplant recipients

CNI have improved the outcome of LT. However, their inherent potential to nephrotoxic and sometimes-inadequate immunosuppressive effect has lead to the usage of newer drugs like SRL. Aim of this study was to review children who received SRL. Thirty-seven (20 women) children post-LT, median age 10.4 yr (0.8-17.4) with a minimum follow-up of six months comprised the study group. Indications for SRL were biopsy-proven resistant acute allograft rejection (n = 12), early CR (n = 12), and CNI-induced nephropathy with MMF intolerance (n = 11). In two patients, the indication was the recurrence of BSEP disease in the allograft. In patients with acute rejection, AST normalized in 10/12 patients. In patients with CR, AST normalized in 6/12 patients. Those with renal impairment showed improvement in their creatinine levels from a mean baseline of 99-56.7 μm (p = 0.03) and their mean cystatin C was 1.02 after SRL. Side effects leading to discontinuation of SRL were seen in three patients. SRL was effective in rescuing patients with acute and chronic allograft rejection and improving renal function in CNI-induced nephropathy group.

Hepatocellular carcinoma in biliary atresia: King's College Hospital experience

OBJECTIVES

To establish risks for development of hepatocellular carcinoma (HCC) in children with biliary atresia (BA), the most common chronic liver disease of childhood.

STUDY DESIGN

In our tertiary referral center database we have identified children with BA who had development of or have been incidentally found to have HCC. Their demographic, clinical, radiologic, and histologic features were analyzed.

RESULTS

Between 1990 and 2008, 387 infants were diagnosed with BA at our center. Of these, three (0.8 %) who underwent operation at a median age of 68 (range 66 to 71) days had development of a histologically proven HCC detected at a median age of 2.1 (range 1.8 to 4.9) years. Another two, referred later, were diagnosed with HCC on their liver explants at ages 1.1 and 17.75 years, respectively. Overall, two had elevated serum levels of alpha-fetoprotein. All five children underwent successful liver transplantation at a median age of 2.1 years (range 1.1 to 17.75) and remain well after a median of 2.5 (range 2 to 5.7) years.

CONCLUSION

HCC develops in a small percentage of children with BA. Serum alpha-fetoprotein levels and ultrasound screening are helpful but not absolute markers of the malignant change. In the absence of the extrahepatic involvement, liver transplantation represents an effective treatment.

Autoimmune liver disease: news and perspectives

Autoimmune liver disorders in childhood include autoimmune hepatitis and autoimmune sclerosing cholangitis. These inflammatory liver disorders are characterised histologically by interface hepatitis, biochemically by elevated transaminase levels and serologically by autoantibodies and increased levels of immunoglobulin G. Autoimmune hepatitis is particularly aggressive in children and progresses rapidly unless immunosuppressive treatment is started promptly. With appropriate treatment 80% of patients achieve remission and long-term survival. Autoimmune sclerosing cholangitis responds to the same treatment used for autoimmune hepatitis in regards to parenchymal inflammation, but bile duct disease progresses in about 50% of cases, leading to a worse prognosis and higher transplantation requirement; it has a high recurrence rate post liver transplant. New strategies aiming at treating unresponsive patients and at curbing specifically the liver autoimmune attack, without provoking unwanted systemic side effects, are being investigated and may be available within the next 5 years.

Autoimmune hepatitis

Autoimmune hepatitis was one of the first liver diseases for which an effective treatment was developed and the benefit proven by randomized controlled trials. Nonetheless, both the diagnosis and the treatment of autoimmune hepatitis remain full of challenges. The clinical spectrum is very wide, ranging from subclinical non-progressive disease to fulminant hepatic failure. Diagnostic criteria based on elevation of IgG, demonstration of characteristic autoantibodies, and histological features of hepatitis in the absence of viral disease are very helpful. However, in some patients, diagnosis remains a clinical challenge. Adequately dosed steroids are the mainstay of remission induction treatment, while remission maintenance is best achieved by azathioprine. Therapeutic alternatives are required in a small group of patients responding insufficiently to these drugs or intolerant to their side effects.

Liver transplantation for propionic acidemia in children

Propionic acidemia (PA) is a rare inherited disorder of branched chain amino acid metabolism; despite improvements in conventional medical management, the long-term outcome remains disappointing. Liver transplantation (LT) has been proposed to minimize the risk of further metabolic decompensations and to improve the quality of life. We performed a retrospective review of all children with PA who underwent LT between 1987 and 2008. Five children were identified with a median age of 1.2 years (range = 0.7-4.1 years) at referral. Four of the children presented clinically at 3 weeks of age or less, and 1 child was diagnosed prenatally. All had metabolic acidosis and hyperammonemia. Two had seizures and required intensive care; this care included inotropic support and continuous venovenous hemofiltration in 1 child. The children were considered for elective LT for the following reasons: frequent metabolic decompensations (2), previous sibling death (2), and elective management (1). One child underwent auxiliary LT, and 4 children received orthotopic grafts (1 living related graft). The median age at LT was 1.5 years (range = 0.8-7.0 years). There was 1 retransplant 3 months after LT due to hepatic artery thrombosis. One year after LT, 1 patient suffered a metabolic stroke with minimal residual neurology. After a median follow-up of 7.3 years (range = 2.2-15.0 years), all the children had normal graft function and a good quality of life with a protein-unrestricted diet and no further metabolic decompensations. In conclusion, LT has a role in the management of PA: it reduces the risk of metabolic decompensation and improves the quality of life. The potential for the development of metabolic sequelae is not completely eliminated.

Guidance for clinical trials for children and adolescents with chronic hepatitis C

Most children with chronic hepatitis C are infected vertically, have a low natural seroconversion rate, and carry a lifetime risk of cirrhosis and cancer. Affected children are usually asymptomatic, and histological findings are mild with a low risk of progression, although 5% develop significant liver disease in childhood.The use of combination treatment with pegylated interferon-α and ribavirin has changed the outcome and prognosis for this disease, with approximately 60% of children achieving sustained viral clearance. Combination therapy is not ideal for children because pegylated interferon is administered subcutaneously, impairs growth velocity, and both interferon and ribavirin have significant adverse effects that affect compliance. In addition, approximately 50% of children infected with genotype 1 do not respond to therapy. Thus, additional treatment options are required including improvement in dosing, reduction in the length of treatment, and evaluation of new drugs, such as protease inhibitors, which could be more effective for patients infected with genotype 1.The primary goal of treatment is to eradicate the infection. The future clinical trial design should ensure that any new drugs demonstrate noninferiority to the present standard regimen in both children and adults. The measure for documenting substantial improvement above present therapy should be increased viral clearance rate or the same clearance rate, with a shorter duration of treatment and/or fewer adverse effects. We do not believe there is any need for a placebo arm because approved therapy is available and new treatments can be compared with present therapy.Safety measures should include the standard recommended laboratory investigations, growth parameters, quality-of-life or psychological measures, and a requirement for long-term follow-up for up to 5 years.

Autoantigen-specific regulatory T cells, a potential tool for immune-tolerance reconstitution in type-2 autoimmune hepatitis

Effector CD4 and CD8 T cell immune responses to cytochrome P450IID6 (CYP2D6), the autoantigen of autoimmune hepatitis type 2 (AIH-2), are permitted by a numerical and functional impairment of CD4(pos) CD25(high) regulatory T cells (T-regs). We aimed to investigate whether T-regs specific for CYP2D6 immunodominant regions and restricted by the appropriate human leukocyte antigen (HLA)-DR molecule can be generated in patients with AIH-2 and can control CD4 and CD8 T cell effectors targeting identical or overlapping CYP2D6 regions. CYP2D6-specific regulatory T cells (CYP2D6 T-regs) were obtained from peptide-pulsed monocyte-depleted peripheral blood mononuclear cells of 17 patients with AIH-2, who were positive for the predisposing HLA-DR7 and/or HLA-DR3 alleles. Their antigen specificity was assessed by cytofluorimetry using HLA class II tetramers and their cytokine profile by intracellular staining. T-reg ability to suppress was ascertained by measuring reduction of CD4(pos) CD25(neg) cell proliferation/effector cytokine secretion and of CD8 T cell cytotoxicity. The most efficient suppression of effector T cell proliferation, inflammatory cytokine release, and cytotoxicity was obtained by coculturing T-regs with CYP2D6-peptide-loaded semimature dendritic cells (smDCs), and smDC-CYP2D6 T-regs also expressed high levels of FOXP3 (forkhead box P3). Possession of the appropriate HLA-DR molecule and recognition of the CYP2D6 autoantigenic sequence were critical to the synergistic smDC-CYP2D6 T-reg immunoregulatory functions, and lack of either element led to poor control of responder cell proliferation and cytokine secretion. Moreover, interferon-γ neutralization significantly boosted the suppressive ability of CYP2D6 T-regs.

CONCLUSION

T-regs generated under CYP2D6-specific conditions and cocultured with smDCs are highly effective at controlling autoreactive T cells, thus providing the basis for a powerful and tailored form of immunotherapy for AIH-2.

Pharmacological management of autoimmune hepatitis

INTRODUCTION

Without prompt immunosuppressive treatment, autoimmune hepatitis is a devastating, albeit rare, liver disease. It affects both adults and children, being particularly aggressive in the latter. Eighty per cent of patients respond satisfactorily to treatment; the other 20% progress to end-stage liver disease and require transplantation.

AREAS COVERED

This review emphasizes the importance of a timely diagnosis of autoimmune hepatitis and provides a practical guide for its treatment. The authors summarize the treatment options available for autoimmune hepatitis and stress that most patients respond successfully to standard treatment with prednisolone and azathioprine, two well-tried and inexpensive drugs. The authors also review the options for difficult-to-treat patients (non-responders and frequent relapsers), for whom newer immunosuppressive agents--usually employed as anti-rejection drugs--have been tried with variable success.

EXPERT OPINION

Autoimmune hepatitis is exquisitely responsive to immunosuppression but treatment must be started as soon as possible to achieve full remission and halt progression of liver disease. New strategies aiming at treating the unresponsive patients and at specifically curbing the liver autoimmune attack, without provoking unwanted systemic side effects, are being investigated and may be available within the next 5 years.

A multifaceted imbalance of T cells with regulatory function characterizes type 1 autoimmune hepatitis

Immunotolerance is maintained by regulatory T cells (Tregs), including CD4(+)CD25(hi), CD8(+)CD28(-), gammadelta, and CD3(+)CD56(+) [natural killer T (NKT)] cells. CD4(+)CD25(hi) cells are impaired in children with autoimmune hepatitis (AIH). Little is known about Tregs in adults with AIH. The aim of this study was to investigate the frequency and function of Treg subsets in adult patients with AIH during periods of active disease and remission. Forty-seven AIH patients (16 with active disease and 31 in remission) and 28 healthy controls were studied. Flow cytometry was used to evaluate surface markers and function-related intracellular molecules in gammadelta, CD8(+)CD28(-), NKT, and CD4(+)CD25(hi) cells. CD4(+)CD25(hi) T cell function was determined by the ability to suppress proliferation and interferon gamma (IFN-gamma) production by CD4(+)CD25(-) target cells. Liver forkhead box P3-positive (FOXP3(+)) cells were sought by immunohistochemistry. In AIH patients, particularly during active disease, CD4(+)CD25(hi) T cells were fewer, expressed lower levels of FOXP3, and were less effective at inhibiting target cell proliferation versus healthy controls. Moreover, although the numbers of CD8(+)CD28(-) T cells were similar in AIH patients and healthy controls, NKT cells were numerically reduced, especially during active disease, and produced lower quantities of the immunoregulatory cytokine interleukin-4 versus controls. In contrast, gammadelta T cells in AIH patients were more numerous versus healthy controls and had an inverted Vdelta1/Vdelta2 ratio and higher IFN-gamma and granzyme B production; the latter was correlated to biochemical indices of liver damage. There were few FOXP3(+) cells within the portal tract inflammatory infiltrate.

CONCLUSION

Our data show that the defect in immunoregulation in adult AIH is complex, and gammadelta T cells are likely to be effectors of liver damage.

Differences in presentation and progression between severe FIC1 and BSEP deficiencies

BACKGROUND & AIMS

Progressive familial intrahepatic cholestasis (PFIC) with normal serum levels of gamma-glutamyltranspeptidase can result from mutations in ATP8B1 (encoding familial intrahepatic cholestasis 1 [FIC1]) or ABCB11 (encoding bile salt export pump [BSEP]). We evaluated clinical and laboratory features of disease in patients diagnosed with PFIC, who carried mutations in ATP8B1 (FIC1 deficiency) or ABCB11 (BSEP deficiency). Our goal was to identify features that distinguish presentation and course of these two disorders, thus facilitating diagnosis and elucidating the differing consequences of ATP8B1 and ABCB11 mutations.

METHODS

A retrospective multi-center study was conducted, using questionnaires and chart review. Available clinical and biochemical data from 145 PFIC patients with mutations in either ATP8B1 (61 "FIC1 patients") or ABCB11 (84 "BSEP patients") were evaluated.

RESULTS

At presentation, serum aminotransferase and bile salt levels were higher in BSEP patients; serum alkaline phosphatase values were higher, and serum albumin values were lower, in FIC1 patients. Elevated white blood cell counts, and giant or multinucleate cells at liver biopsy, were more common in BSEP patients. BSEP patients more often had gallstones and portal hypertension. Diarrhea, pancreatic disease, rickets, pneumonia, abnormal sweat tests, hearing impairment, and poor growth were more common in FIC1 patients. Among BSEP patients, the course of disease was less rapidly progressive in patients bearing the D482G mutation.

CONCLUSIONS

Severe forms of FIC1 and BSEP deficiency differed. BSEP patients manifested more severe hepatobiliary disease, while FIC1 patients showed greater evidence of extrahepatic disease.

N-acetylcysteine improves the viability of human hepatocytes isolated from severely steatotic donor liver tissue

Hepatocyte transplantation is dependent on the availability of good quality human hepatocytes isolated from donor liver tissue. Hepatocytes obtained from livers rejected for transplantation on the grounds of steatosis are often of low viability and not suitable for clinical use. The aim of this study was to evaluate the effects of the antioxidant N-acetylcysteine (NAC) on the function of hepatocytes isolated from steatotic donor livers. Human hepatocytes were isolated from 10 severely steatotic (>60%) donor livers rejected for transplantation. The left lateral segment of the donor liver was dissected into two equal size pieces and randomized to NAC or control. NAC (5 mM) was added to the first perfusion buffer of the standard collagenase digestion technique. Cells from tissues perfused with NAC had a significantly higher mean viability (81.1 ± 1.7% vs. 66.0 ± 4.7%; p = 0.003) and cell attachment (1.08 ± 0.26 vs. 0.67 ± 0.18 OD units; p = 0.012). Addition of NAC during isolation of human hepatocytes from steatotic donor liver tissue significantly improved the outcome of cell isolation. Further studies are needed to investigate the mechanism(s) of this effect. Incorporation of NAC in the hepatocyte isolation protocol could increase the availability of hepatocytes for transplantation.

Adaptive immunity in autoimmune hepatitis

The histological lesion of interface hepatitis, with its dense portal cell infiltrate consisting of lymphocytes, monocytes/macrophages and plasma cells, was the first to suggest an autoaggressive cellular immune attack in the pathogenesis of autoimmune hepatitis (AIH). Immunohistochemical studies, focused on the phenotype of inflammatory cells infiltrating the liver parenchyma, have shown a predominance of alphabeta-T cells. Amongst these cells, the majority have been CD4 helper/inducers, while a sizeable minority have consisted of CD8 cytotoxic/suppressors. Lymphocytes on non-T cell lineage included natural killer cells, monocytes/macrophages and B lymphocytes. For autoimmunity to arise, the self-antigenic peptide, embraced by an human leukocyte antigen (HLA) class II molecule, must be presented to an uncommitted T helper (T(H)0) lymphocyte by professional antigen-presenting cells. Once activated and according to the presence in the milieu of interleukin 12 (IL-12) or IL-4, T(H)0 lymphocytes can differentiate into T(H)1 cells, which are pivotal to macrophage activation; enhance HLA class I expression, rendering liver cells vulnerable to CD8 T-cell attack; and induce HLA class II expression on hepatocytes; or they can differentiate into T(H)2 cells, which produce IL-4, IL-10 and IL-13, cytokines favouring autoantibody production by B lymphocytes. Autoantigen recognition is tightly controlled by regulatory mechanisms, such as those exerted by CD4+CD25(high) regulatory T cells. Numerical and functional regulatory T cell impairment characterises AIH and permits the perpetuation of effector immune responses with ensuing persistent liver destruction. Advances in the study of autoreactive T cells stem mostly from AIH type 2, where the main autoantigen, cytochrome P450IID6 (CYP2D6), is known to enable characterisation of antigen-specific immune responses.

A single center experience of donation after cardiac death liver transplantation in pediatric recipients

Many centers are now performing DCD adult LT. There has been a reluctance to transplant pediatric recipients with DCD livers due to concern over the medium to long-term outcome. We describe the outcome of 14 children (median age seven yr, 8 months-16 yr) that underwent LT with DCD grafts from July 2001 to December 2007. Donors had a median age of 23 yr (10-64), intensive care stay of five d (2-14) and bilirubin of 9 mmol/L (6-60). Median warm and cold ischemic time was 16 min (11-29) and seven h (5.5-8.4). Livers were transplanted as a whole organ (4), reduced graft (8), formal split (1) or auxiliary transplant (1). Compared to DBD recipients AST was significantly higher on the first three post-operative days and there was no difference in the INR, bilirubin or GGT out to 12 months. There were no biliary or vascular complications and patient and graft survival is 100% at a median follow-up of 41.8 months (1.7-74 months). LT with DCD grafts in pediatric recipients can be performed with low morbidity and excellent short-to-medium term patient and graft outcome.

Long-term outcome and management of hepatopulmonary syndrome in children

We aim to report a single center experience of the management and long term outcome of HPS in pediatric liver transplant recipients. A retrospective review of children with HPS from 1990 to 2004.

INCLUSION CRITERIA

liver disease or portal hypertension, hypoxemia (PaO(2) < 70 mmHg or SaO(2) < 95%) and intrapulmonary shunting documented by macroaggregated albumin scan ratio of >4% (classified mild group [<20%], moderate group [20-40%] and severe group [>40%]). Resolution of HPS post-liver transplant was defined as PaO(2) > 70 mmHg or SaO(2) > 95%. Eighteen children (six male [34%], median age at diagnosis of HPS 8.6 [1-15.5] yr) had HPS: biliary atresia (n = 8), idiopathic biliary cirrhosis (n = 4), progressive intrahepatic cholestasis (n = 2), miscellaneous (n = 4). The majority had mild shunting (n = 8). Fourteen underwent transplantation with resolution of HPS in 13. Six developed complications: hepatic artery thrombosis (n = 4), biliary (n = 2). Four children died (28%), two pretransplant. There was a tendency towards shunt fraction worsening to a slower degree over time. One-yr survival rate post-transplant was 93%. Median PaO(2) was significantly lower in non-survivors compared to survivors (43 vs. 55.2 mmHg, p = 0.03). There was correlation between oxygen parameters pretransplant and time to HPS resolution post-transplant. HPS is reversible after transplant, but is associated with increasing mortality and morbidity.

Aetiopathogenesis of autoimmune hepatitis

Interface hepatitis, histological hallmark of autoimmune hepatitis (AIH), is a dense portal mononuclear cell infiltrate invading the parenchyma, consisting of CD4 and CD8 T-lymphocytes, monocytes/macrophages and plasma cells. What triggers AIH is unknown, but there is evidence that failure of immune homeostasis plays a permissive role allowing liver autoantigen-specific cells to attack hepatocytes. Damage is likely to be orchestrated by CD4 T-lymphocytes recognizing an autoantigenic liver peptide. For autoimmunity to arise, the peptide, embraced by an HLA class II molecule, must be presented to naïve CD4 T-helper (T(H)0) cells by professional antigen-presenting cells. Once activated, T(H)0 cells can differentiate into T(H)1 cells, which are pivotal to macrophage activation, enhance HLA class I expression, rendering liver cells vulnerable to CD8 T-cell attack, and induce HLA class II expression on hepatocytes; or into T(H)2 cells producing IL-4, IL-10 and IL-13, cytokines favouring autoantibody production by B-lymphocytes. Autoantigen recognition is tightly controlled by regulatory mechanisms, such as those exerted by CD4+CD25+ regulatory T-cells (T-regs). Numerical and functional T-reg impairment characterizes AIH, particularly during active disease. Advances in the study of autoreactive T-cells stem mostly from AIH type 2, where the main autoantigen, CYP2D6, is known enabling characterization of antigen-specific immune responses. Monocyte involvement in the autoimmune liver attack has been recently reported.

Autoantibodies and their antigens in autoimmune hepatitis

Autoantibody detection assists in the diagnosis and allows differentiation of autoimmune hepatitis (AIH) type 1 (AIH-1), characterized by antinuclear antibody (ANA) and/or smooth muscle antibody (SMA), and type 2 (AIH-2), distinguished by the presence of antibodies to liver-kidney microsome type 1 (anti-LKM1) and/or antibodies to liver cytosol type 1 (anti-LC1). Detection of atypical perinuclear antineutrophil cytoplasmic antibodies (pANCA) and anti-soluble liver antigen (SLA) antibodies can act as an additional pointer toward the diagnosis of AIH, particularly in the absence of the conventional autoantibodies. Routine autoantibody testing by indirect immunofluorescence has been recently complemented by molecular assays based on purified or recombinant antigens. Although the AIH-1-specific ANA and SMA targets need better definition, those of anti-LKM1 and anti-LC1 in AIH-2 have been clearly identified; the fine specificity of antibody reactivity and its clinical relevance to disease pathogenesis are the focus of ongoing investigation. This article critically discusses the current knowledge of the diagnostic and clinical significance of AIH-related autoantibody reactivities, focusing on key issues that the physician needs to be aware of to be able to request the appropriate testing and to interpret correctly the laboratory results within the clinical context of the patient.