Elevated fractional donor-derived cell-free DNA during subclinical graft injury after liver transplantation.

Personalized immunosuppression (IS) promises to improve the balance of necessary control of alloreactivity and dose-dependent adverse effects of long-term IS such as kidney insufficiency, infections, and malignancies. The majority of liver transplantation (LT) recipients exhibit graft injuries (graft inflammation and/or fibrosis) that are not eligible for an IS reduction according to current Banff criteria, even when liver enzymes are normal or only marginally elevated. This cross-sectional study evaluated the noninvasive prediction of such subclinical graft injuries in surveillance liver biopsies via donor-derived cell-free DNA (dd-cfDNA). Absolute and fractional dd-cfDNA increased stepwise from patients without histological signs of rejection (n = 26) over subclinical graft injury (n = 61), including subclinical T cell-mediated rejection to clinical overt T cell-mediated rejection (n = 21). Thus, fractional plasma dd-cfDNA was significantly elevated paired to surveillance biopsies with relevant subclinical graft injury according to 2016 Banff criteria compared with those with minimal or absent histological graft injury. In contrast, the presence of donor-specific anti-human leukocyte antigen antibodies was not associated with the amount of dd-cfDNA. The sensitivity and specificity of fractional dd-cfDNA to noninvasively predict relevant subclinical graft injury was rather limited with 73% and 52% at the cutoff value of 2.1% fractional dd-cfDNA. The positive predictive value of fractional dd-cfDNA above 2.1% was 76% to noninvasively predict subclinical graft injury, calculated on the prevalence of graft injury in our prospective surveillance biopsy program, whereas the negative predictive values was not predictive (47%). In conclusion, dd-cfDNA has a rather limited diagnostic fidelity in addition to other noninvasive markers for the assessment of subclinical graft injury in personalized IS approaches after LT in a cross-sectional setting.

Preferential accumulation of T helper cells but not cytotoxic T cells characterizes benign subclinical rejection of human liver allografts.

Subclinical rejection (SCR) is a common event in protocol biopsies after liver transplantation (LT). So far the interpretation of the underlying histological changes and clinical significance is limited. Previous studies were restricted to SCR manifestations within the first weeks after transplantation with limited follow-up. We analyzed clinical data from our prospective protocol biopsy program and found late SCR (at least 3 months after transplantation) to be a common event (41/94 patients). SCR manifested much later than acute cellular rejection (ACR). In the second year after transplantation, the SCR incidence in protocol biopsies reached a plateau of approximately 25% and remained at this level until the latest observed manifestations more than 5 years after transplantation. During a median follow-up of 32 months after SCR, no acute or chronic rejection, relevant graft fibrosis, graft loss, or liver-related death occurred even without specific therapy for SCR. Immunophenotyping of liver biopsies during SCR showed that similar to ACR, the composition of intrahepatic T cells depended on the severity of histological rejection. However, SCR showed a different pattern of infiltrating T cells with a stronger accumulation of CD4(+) cells, an increasing CD4(+) /CD8(+) ratio, and an increasing CD4(+) forkhead box P3 (FOXP3)(+) regulatory T cell (Treg)/CD8(+) ratio, which was not seen in ACR. These intrahepatic T cell patterns were not reflected in the peripheral blood. In conclusion, late SCR after LT has a good clinical prognosis, and it seems safe to leave it untreated. This benign clinical course compared to ACR is associated with intrahepatic T cell infiltration patterns showing less cytotoxic T cells and more CD4(+) FOXP3(+) Tregs. Liver Transplantation 22 943-955 2016 AASLD.

Intrahepatic regulatory T cells in autoimmune hepatitis are associated with treatment response and depleted with current therapies.

BACKGROUND & AIMS: Autoimmune hepatitis (AIH) is a chronic autoimmune liver disease usually requiring life-long immunosuppression. The mechanisms for disease initiation and chronicity are largely unknown. A contribution of deficient regulatory T cells (Tregs) in the blood was controversially discussed recently. So far investigations in the target organ have been limited to single parameter analysis in untreated AIH. METHODS: We retrospectively analysed the pattern of liver infiltrating T, B and regulatory T cells quantitatively with simultaneous multicolour immunofluorescence before (n=45) and under (n=31) therapy in adult AIH type 1 (AIH-1) patients. RESULTS: Intrahepatic CD4(+) cells dominate over CD8(+) at diagnosis, but with increasing disease activity the CD4(+)/CD8(+) ratio approached one. While there is no change of Tregs in the blood, they are enriched with effector T cells (Teffs) within the liver of patients with untreated AIH-1 with a constant Treg/Teff ratio. Even more importantly, immunosuppression mostly with steroids and azathioprine caused a disproportional loss of intrahepatic Tregs. Patients reaching biochemical remission had higher intrahepatic Treg/Teff and Treg/B cell ratios compared to patients failing to reach remission. In vitro proliferation of Tregs seemed to be more suppressed by prednisolone than expansion of Teffs. Furthermore, intraportal B cells correlated with serum IgG suggesting an autochthonous intrahepatic IgG production. CONCLUSIONS: Intrahepatic Tregs are rather enriched than numerically deficient in untreated AIH-1. The disproportional decrease of intrahepatic Tregs during therapy might explain high relapse rates after discontinuation of immunosuppression. Thus, future therapies increasing intrahepatic immunoregulation might be better suited for long-term control of AIH.