The diagnosis of HEV infection is technically challenging and should be made simultaneously with RT-PCR methods, viral load quantification and serological markers. In immunosuppressed children who develop chronic hepatitis, the prevalence of HEV is high and could explain the chronic liver inflammation potentially leading to cirrhosis. Re-infection by different HEV strains from zoonotic transmission can result in progressive liver disease in immunocompromised children.

Background Autoimmune hepatitis (AIH) in humans is a severe inflammatory liver disease, characterized by interface hepatitis, the presence of circulating autoantibodies and hyper-gammaglobulinemia. There are two types of AIH, type-1 (AIH-1) and type-2 (AIH-2) characterized by distinct autoimmune serology. Patients with AIH-1 are positive for anti-smooth muscle and/or anti-nuclear (SMA/ANA) autoantibodies whereas patients with AIH-2 have anti-liver kidney microsomal type 1 (anti-LKM1) and/or anti-liver cytosol type 1 (anti-LC1) autoantibodies. Cytochrome P4502D6 (CYP2D6) is the antigenic target of anti-LKM1 and formiminotransferase cyclodeaminase (FTCD) is the antigenic target of anti-LC1. It is known that AIH, both type-1 and type-2, is strongly linked to the Human Leukocyte Antigen (HLA) alleles -DR3, -DR4 and -DR7. However, the direct evidence of the association of HLA with AIH is lacking. Methods We developed a novel mouse model of AIH using the HLA-DR3 transgenic mouse on the non-obese diabetic (NOD) background (HLA-DR3 NOD) by immunization of HLA-DR3− and HLA-DR3+ NOD mice with a DNA plasmid, coding for human CYP2D6/FTCD fusion protein. Results Immunization with CYP2D6/FTCD leads to a sustained elevation of alanine aminotransferase (ALT), development of ANA and anti-LKM1/anti-LC1 autoantibodies, chronic immune cell infiltration and parenchymal fibrosis on liver histology in HLA-DR3+ mice. Immunized mice also showed an enhanced Th1 immune response and paucity of the frequency of regulatory T-cell (Treg) in the liver. Moreover, HLA-DR3+ mice with exacerbated AIH showed reduced diversity and total load of gut bacteria. Conclusion Our humanized animal model has provided a novel experimental tool to further elucidate the pathogenesis of AIH and to evaluate the efficacy and safety of immunoregulatory therapeutic interventions in vivo.

NK-cell resistance to transduction is a major technical hurdle for developing NK-cell immunotherapy. By using Baboon envelope pseudotyped lentiviral vectors (BaEV-LVs) encoding eGFP, we obtained a transduction rate of 23.0 ± 6.6% (mean ± SD) in freshly-isolated human NK-cells (FI-NK) and 83.4 ± 10.1% (mean ± SD) in NK-cells obtained from the NK-cell Activation and Expansion System (NKAES), with a sustained transgene expression for at least 21 days. BaEV-LVs outperformed Vesicular Stomatitis Virus type-G (VSV-G)-, RD114-and Measles Virus (MV)-pseudotyped LVs (p < 0.0001). mRNA expression of both BaEV receptors, ASCT1 and ASCT2, was detected in FI-NK and NKAES, with higher expression in NKAES. Transduction with BaEV-LVs encoding for CAR-CD22 resulted in robust CAR-expression on 38.3 ± 23.8% (mean ± SD) of NKAES cells, leading to specific killing of NK-resistant pre-BALL -RS4;11 cell line. Using a larger vector encoding a dual CD19/CD22-CAR, we were able to transduce and re-expand dual-CAR-expressing NKAES, even with lower viral titer. These dual-CAR-NK efficiently killed both CD19 KO-and CD22 KO-RS4;11 cells. Our results suggest that BaEV-LVs may efficiently enable NK-cell biological studies and translation of NK-cell-based immunotherapy to the clinic.

Autoimmune hepatitis (AIH) is characterized by a loss of immunological tolerance to hepatocytes. Patients respond well to immunosuppression but progression to endstage liver disease occurs in 10%-20% of cases, leading to liver transplantation. Using a murine model of type 2 AIH, we identified susceptibility factors for autoimmune hepatitis and attempted to restore immunological tolerance to liver autoantigens. An increased ectopic expression of a liver autoantigen (FTCD) in the thymus leading to reduced numbers of circulating autoreactive T cells was sufficient to prevent development of AIH in mice. However, in the presence of a reduced central tolerance to FTCD, a strong regulatory T-cell response was able to inhibit proliferation of liver-specific autoreactive T cells and prevent AIH. Development of a severe AIH stemmed from reduced numbers of functional regulatory T cell (Tregs) leading to an increased proliferation of FTCD-specific autoreactive T and B cells. Adoptive transfer of ex vivo expanded CXCR31 Tregs in mice with AIH efficiently targeted the inflamed liver, restored peripheral tolerance to FTCD, and induced remission of AIH. Conclusion: Peripheral tolerance to liver autoantigens in AIH is paramount. Autologous infusion of ex vivo expanded CXCR31 Tregs in AIH patients could be an effective therapeutic approach to restore peripheral tolerance and induce remission of AIH. (HEPATOLOGY 2013;57:217-227)

TTV infection is widespread, and its replication is closely related to immune status and viral coinfection. High TTV viremia is not associated with hepatitis after OLT, but, conversely, liver inflammatory activity impairs TTV replication.

Autoimmune hepatitis (AIH) is known as a T cell–mediated disease. However, AIH patients refractory to conventional treatment have been successfully treated with anti‐CD20‐mediated B‐cell depletion. The aim of this project was to understand the immunological changes underlying the AIH remission caused by B‐cell depletion in an experimental model of AIH. C57BL/6 AIH mice, xenoimmunized with DNA coding for human liver antigens, were treated with a single dose of depleting mouse anti‐CD20 antibody at the peak of liver inflammation. Liver inflammation, alanine aminotransferase levels, chemokine (C‐X‐C) ligand 10 expression, and circulating B‐cell, autoantibody, and total immunoglobulin G levels were monitored following depletion. T‐cell and B‐cell phenotype and function were characterized. Administration of a single dose of anti‐CD20 resulted in a drastic reduction of liver inflammation accompanied by a significant reduction of alanine aminotransferase levels and of proinflammatory chemokine (C‐X‐C) ligand 10 expression. The treatment did not result in significant changes in total immunoglobulin G levels or autoantibodies. There were significantly more naive and less antigen‐experienced CD4+ and CD8+ T cells, and T‐cell proliferation was significantly reduced following anti‐CD20 treatment. B cells served as antigen‐presenting cells to CD4+ T cells. Anti‐CD20 treatment also led to a profound reduction of T follicular helper cells. Conclusion: B cells play an active role in the pathogenesis of AIH in antigen presentation processes and the modulation of T‐cell functions and influence the T follicular helper–cell population; this active role of B cells could explain the success of B‐cell depletion for remission of AIH despite its classification as a T cell–mediated autoimmune liver disease. (Hepatology 2015;62:1511–1523)

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Autoimmune hepatitis (AIH), like many autoimmune diseases, is most prevalent in young women. The immunological basis of this age and sex susceptibility bias was investigated in a murine model of AIH. Xenoimmunization of 7-week-old female C57BL/6 mice resulted in more severe AIH with higher levels of liver inflammation, serum alanine aminotransferase, specific T-cell cytotoxicity, and autoantibody than younger and older females. Vaccinated males developed minimal liver inflammation and higher percentages of CD4 FoxP31 regulatory T cell in peripheral blood mononuclear cells, spleen, and liver than females. Regulatory T cells (Tregs) were virtually absent in liver-lymphocytes infiltrates of females. Castration of C57BL/6 mice, with or without 17b-estradiol supplementation, did not modify susceptibility in males, nor Treg numbers, suggesting minimal contribution of testosterone and estradiol to autoimmune hepatitis (AIH) susceptibility. Xenoimmunized Aire(1/0) mouse displayed similar AIH susceptibility, sex bias, and Tregs numbers as C57BL/6 mice, suggesting that susceptibility in females is not the result of less stringent thymic central tolerance. Autoreactive B cell response against formiminotransferase-cyclodeaminase correlated with disease activity, possibly linking B-cell autoreactivity and AIH pathogenesis. Conclusion: Peripheral tolerance and development of regulatory T cells after self-mimicking antigen exposure, and not sexual hormone nor central tolerance, are the main factors for susceptibility to AIH in females. (HEPATOLOGY 2010;51:1789-1798 P revalence of most autoimmune diseases shows a striking sex difference, with women being affected more often than men.1,2 The ratio of female patients to male ranges from 20:1 in Sjögren's syndrome, to 3:2 in multiple sclerosis.2 Less frequently, the ratio approaches 1:1, as in ulcerative colitis and diabetes.2 In autoimmune hepatitis (AIH), the female to male ratio ranges from 3:1 in type 1 AIH to 9:1 in type 2 AIH. 3Differences in the immune response have also been observed between women and men. Higher level of antibodies and stronger T cell activation are observed in women after vaccination. 4 Women also have higher absolute numbers of CD4 þ T cells and produce higher levels of Th1 cytokines than men.5 Age also affects immune responses, including incidence of several autoimmune diseases. In AIH, 40% of cases of type 1 are diagnosed before the age of 18 years, with a mean age at onset of 10 years, 6,7 and 80% of cases of type 2 are diagnosed before the age of 18 years, with a mean age at onset of 6.5 years.6,7 A second peak of incidence of AIH has also been reported in women after menopause.8 These prepubertal and postmenopausal peaks of incidence suggest that the hormonal status could influence susceptibility to AIH.Research on autoimmune diseases sex bias is scarce. Studies on AIH susceptibility factors, including its sex bias, have been severely limited by the lack of experimental models. Recently, a murine experimental model of AIH has been produced 9 in whi...