Monitoring "de novo" autoimmune hepatitis (LKM positive) by serum type-IV collagen after liver transplant: a paediatric case

Rethinking de novo immune hepatitis, an old concept for liver allograft rejection: Relevance of glutathione S-transferase T1 mismatch

Antibody-mediated rejection (AMR) in liver transplantation has long been underestimated. The concept of the liver as an organ susceptible to AMR has emerged in recent years, not only in the context of the major histocompatibility complex with the presence of HLA donor-specific antibodies, but also with antigens regarded as “minor”, whose role in AMR has been demonstrated. Among them, antibodies against glutathione S-transferase T1 have been found in 100% of patients with de novo autoimmune hepatitis (dnAIH) when studied. In its latest update, the Banff Working Group for liver allograft pathology proposed replacing the term dnAIH with plasma cell (PC)-rich rejection. Antibodies to glutathione S-transferase T1 (GSTT1) in null recipients of GSTT1 positive donors have been included as a contributory but nonessential feature of the diagnosis of PC-rich rejection. Also in this update, non-organ-specific anti-nuclear or smooth muscle autoantibodies are no longer included as diagnostic criteria. Although initially found in a proportion of patients with PC-rich rejection, the presence of autoantibodies is misleading since they are not disease-specific and appear in many different contexts as bystanders. The cellular types and proportions of the inflammatory infiltrates in diagnostic biopsies have been studied in detail very recently. PC-rich rejection biopsies present a characteristic cellular profile with a predominance of T lymphocytes and a high proportion of PCs, close to 30%, of which 16.48% are IgG4⁺. New data on the relevance of GSTT1-specific T lymphocytes to PC-rich rejection will be discussed in this review.

De novo autoimmune hepatitis in liver transplant: State-of-the-art review

In the two past decades, a number of communications, case-control studies, and retrospective reports have appeared in the literature with concerns about the development of a complex set of clinical, laboratory and histological characteristics of a liver graft dysfunction that is compatible with autoimmune hepatitis. The de novo prefix was added to distinguish this entity from a pre-transplant primary autoimmune hepatitis, but the globally accepted criteria for the diagnosis of autoimmune hepatitis have been adopted in the diagnostic algorithm. Indeed, de novo autoimmune hepatitis is characterized by the typical liver necro-inflammation that is rich in plasma cells, the presence of interface hepatitis and the consequent laboratory findings of elevations in liver enzymes, increases in serum gamma globulin and the appearance of non-organ specific auto-antibodies. Still, the overall features of de novo autoimmune hepatitis appear not to be attributable to a univocal patho-physiological pathway because they can develop in the patients who have undergone liver transplantation due to different etiologies. Specifically, in subjects with hepatitis C virus recurrence, an interferon-containing antiviral treatment has been indicated as a potential inception of immune system derangement. Herein, we attempt to review the currently available knowledge about de novo liver autoimmunity and its clinical management.

Incidence and risk factors associated with de novo autoimmune hepatitis after liver transplantation

BACKGROUND/AIMS

De novo autoimmune hepatitis (AIH) describes the development of hepatitis with autoimmune features in liver transplant (LT) patients without prior diagnosis of AIH. We aimed to evaluate the incidence and risk factors for de novo AIH.

METHODS

A cohort of 576 patients with LT for aetiologies other than AIH was evaluated.

RESULTS

De novo AIH was diagnosed in 17 patients (3%) with an overall incidence of 4.0 cases per 1000 patient-years. By univariate Cox analysis, patients who received cyclosporine A had lower risk (HR 0.24, 95% CI 0.07-0.80, P = 0.02), whereas patients who had female donors (HR 3.03, 95% CI 1.11-8.25, P = 0.03), donors ≥40-years (HR 6.95, 95% CI 1.93-25.03, P = 0.003), and those who received tacrolimus (HR 4.39, 95% CI 1.47-13.13, P = 0.008) and mycophenolate mofetil (HR 6.37, 95% CI 1.62-25.13, P = 0.008) had higher risk. Survival was similar in patients with de novo AIH compared with the LT population (mean survival time, 17 ± 1.5 vs. 16 ± 0.5 years, Log-rank test; P = 0.4).

CONCLUSIONS

The incidence of de novo AIH is low and does not impact on long-term survival. Recipients of female or older donor grafts, or recipients using tacrolimus, or mycophenolate mofetil as part of their immunosuppressive regimen have a higher risk of de novo AIH, whereas LT recipients maintained on cyclosporine A have a lower risk.

Diagnosis, pathogenesis, and treatment of autoimmune hepatitis after liver transplantation

Autoimmune hepatitis can recur or appear de novo after liver transplantation, and it can result in hepatic fibrosis, graft loss, and re-transplantation. The goals of this review are to describe the prevalence, manifestations, putative pathogenic mechanisms, outcomes, and management of these occurrences. Autoimmune hepatitis recurs in 8-12 % of transplanted patients at 1 year and 36-68 % at 5 years. Recurrence may be asymptomatic and detected only by surveillance liver test abnormalities or protocol liver tissue examination. Autoantibodies that characterized the original disease, hypergammaglobulinemia, increased serum immunoglobulin G level, and histological findings of interface hepatitis, lymphoplasmacytic infiltration, perivenular hepatocyte necrosis, pseudo-rosetting, and acidophil bodies typify recurrence. Premature corticosteroid withdrawal and pre-transplant severity of the original disease are possible risk factors. De novo autoimmune hepatitis occurs in 1-7 % of patients 0.1-9 years after transplantation, especially in children. The appearance of autoantibodies may herald its emergence, and antibodies to glutathione-S-transferase T1 have been predictive of the disease. Recurrent disease may reflect recruitment of residual memory T lymphocytes and host-specific genetic predispositions, whereas de novo disease may reflect an allo-antigenic immune response and molecular mimicries that override self-tolerance. Treatment should be appropriate for autoimmune hepatitis and not based on anti-rejection drugs. Corticosteroid therapy alone or combined with azathioprine is the essential treatment. The substitution of mycophenolate mofetil for azathioprine and switch of the calcineurin inhibitor or its replacement with rapamycin have also been used for refractory disease. Re-transplantation has been necessary in 8-23 %.

Autoantibodies in autoimmune liver disease

Autoantibodies indicate an immune reactive state, but in liver disease they lack pathogenicity and disease specificity. Antinuclear antibodies, smooth muscle antibodies, antibodies to liver/kidney microsome type 1, antimitochondrial antibodies, and perinuclear antineutrophil cytoplasmic antibodies constitute the standard serological repertoire that should be assessed in all liver diseases of undetermined cause. Antibodies to soluble liver antigen/liver pancreas, asialoglycoprotein receptor, actin, liver cytosol type 1, nuclear antigens specific to primary biliary cirrhosis, and pore complex antigens constitute an investigational repertoire that promises to have prognostic and diagnostic value. These autoantibodies may emerge as predictors of treatment response and outcome. Antibodies to histones, doubled-stranded DNA, chromatin, and lactoferrin constitute a supplemental repertoire, and they support the immune nature of the liver disease. Final diagnoses and treatment strategies do not depend solely on serological markers. Autoantibodies are floating variables, and their behavior does not correlate closely with disease activity. There are no minimum levels of significant seropositivity, especially in children. Over-interpretation is the major pitfall in the clinical application of the serological results. New autoantibodies will emerge as the search for target antigens and key pathogenic pathways continues.

Autoimmune hepatitis after liver transplantation and other lessons of self-intolerance

Autoimmune hepatitis has been described as recurrent or de novo disease after transplantation. The legitimacy of these diagnoses and the bases for their occurrence are unknown. To better understand these aspects of allograft dysfunction, the purported pathogenic mechanisms of classical autoimmune hepatitis were reviewed and extrapolated to recurrent and de novo disease after transplantation. Loss of self-tolerance may relate to defects in the negative selection of autoreactive immunocytes and the clonal expansion of promiscuous lymphocytes that are cross-reactive to homologous antigens (molecular mimicry). Repopulation of the allograft with recipient antigen-presenting cells and the presence of primed promiscuous cytotoxic T cells within the recipient are likely factors for recurrent disease. Targets may be the same peptides that triggered the original disease, donor-derived class II antigens of the major histocompatibility complex, or homologous antigens associated with unidentified hepatotrophic viruses. De novo disease is probably due to similar mechanisms, but its predilection for children suggests that thymic dysfunction associated with cyclosporine treatment may be a factor. Corticosteroid therapy is effective in each condition. In conclusion, recurrent and de novo autoimmune hepatitis after transplantation are examples of self-intolerance. The mechanisms that perturb immunologic homeostasis in this human model of the classical disease must be studied more rigorously.