Autoimmune Liver Injury Research Articles

Stellate Cell Activation and Imbalanced Expression of TGF-β1/TGF-β3 in Acute Autoimmune Liver Lesions Induced by ConA in Mice.

Objective. To study the pathogenic feature of liver injury, activation of hepatic stellate cells, and dynamic expression of TGF-β1/TGF-β3 to reveal their role in liver injury induced by ConA. Methods. Mice were randomly divided into control group and ConA treatment group. ConA (20 mg/kg) was injected through vena caudalis in ConA treatment group; the controls received the same volume of saline injection. After injection for 2 h, 8 h, 24 h, and 48 h, animals were terminated. Blood, liver, and spleen were harvested. Liver function and histopathology were studied. α-SMA, vimentin, TGF-β1, and TGF-β3 were detected. Results. After ConA injection, liver damage started to increase. Expression of α-SMA, vimentin, TGF-β1, and TGF-β3 was significantly enhanced; all above indicators reached peak at 8 h; but from 24 h after ConA injection, TGF-β3 expression began to decline, while the TGF-β1/TGF-β3 ratio at 48 h was significantly lower than control. Conclusion. (1) Autoimmune liver injury induced by ConA showed time-based features, in which the most serious liver lesions happened at 8 h after ConA injection. (2) Early activation of HSC and imbalance expression of TGF-β1 and TGF-β3 existed in ConA-induced acute autoimmune liver injury, which may be associated with liver dysfunction and the mechanisms of progression to fibrosis.

Effects of kinsenoside, a potential immunosuppressive drug for autoimmune hepatitis, on dendritic cells/CD8+ T cells communication in mice.

KD treatment elicits immunosuppression against autoimmune liver injury by targeting VEGFR2, followed by diminishing the cross-talk of metabolism-related PI3K-AKT and inflammation-related JAK2-STAT3 pathways, and thereby disrupts DC-induced cross-priming of CD8+ T cell responses. (Hepatology 2016;64:2135-2150).

Autoimmune hepatitis: From mechanisms to therapy

Autoimmune hepatitis (AIH) is a progressive inflammatory hepatopathy and an important cause of end-stage liver disease. Its aetiology remains unknown, though both genetic and environmental factors are involved in its development. The major mechanism of autoimmune liver damage involves immune reactions against host liver antigens. Numerical and functional defects of regulatory T-cells play a permissive role enabling autoimmune liver injury to occur and persist. The most typical features of AIH are female preponderance, hypergammaglobulinaemia, seropositivity for circulating autoantibodies and a picture of interface hepatitis on histology. Two types of AIH are distinguished according to serological profile: AIH type 1 patients are positive for anti-nuclear and/or anti-smooth muscle antibodies, whereas AIH type 2 patients are defined by the positivity for anti-liver kidney microsomal type 1 antibody and/or for anti-liver cytosol type 1 antibody. Clinical manifestations are variable, and AIH onset is often ill-defined, frequently mimicking acute hepatitis; its course may be fluctuating. AIH responds to immunosuppressive treatment in the majority of cases. Steroids with or without azathioprine should be instituted promptly upon diagnosis. Remission is achieved in some 80% of patients. For the remaining 20% of patients, alternative immunosuppressive agents such as mycophenolate mofetil and calcineurin inhibitors are an option. Liver transplantation should be considered for those patients who progress to cirrhosis and develop complications of end-stage liver disease, as well as for those presenting with acute liver failure; outcomes are excellent, although the disease may recur in the allograft.

Immunology of hepatic diseases during pregnancy.

The mother's immune system has to adapt to pregnancy accepting the semi-allograft fetus and preventing harmful effects to the developing child. Aberrations in feto-maternal immune adaptation may result in disease of the mother, such as liver injury. Five pregnancy-associated liver disorders have been described so far, however, little is known concerning immune alterations promoting the respective disease. These liver disorders are pre-eclampsia, hemolysis, elevated liver enzymes, low platelet count (HELLP), acute fatty liver, hyperemesis gravidarum, and intrahepatic cholestasis of pregnancy. On the other hand, pre-existing autoimmune liver injury of the mother can be affected by pregnancy. This review intends to summarize current knowledge linking feto-maternal immunology and liver inflammation with a special emphasis on novel potential biomarkers.

MicroRNA-674-5p/5-LO axis involved in autoimmune reaction of Concanavalin A-induced acute mouse liver injury.

Autoimmune hepatitis is characterized, in part, by the pathways involving cysteinyl-leukotriene metabolites of arachidonic acid, the dynamics of which remain unclear. Here, we explored post-transcriptional regulation in the 5-lipoxygenase (5-LO) pathway of arachidonic acid in a Concanavalin A (Con A) induced mouse model. We found that Con A administration lead to 5-LO overexpression and cysteinyl-leukotriene release in early hepatic injury, which was attenuated by cyclosporin A pretreatment. Subsequent microarray and qRT-PCR analysis further showed that microRNA-674-5p (miR-674-5p) displayed a significant decrease in expression in Con A-damaged liver. Noting that miR-674-5p harbors a potential binding region for 5-LO, we further transfected hepatic cell lines with overexpressing miR-674-5p mimic and discovered a negative regulating effect of miR-674-5p on 5-LO expression in the presence of IL-6 or TNF-α. These findings suggest that miR-674-5p might be a negative regulator in 5-LO mediated autoimmune liver injury, representing a compelling avenue towards future therapeutic interventions.

Autoimmune hepatitis: From mechanisms to therapy

Autoimmune hepatitis (AIH) is a progressive inflammatory hepatopathy and an important cause of end-stage liver disease. Its aetiology remains unknown, though both genetic and environmental factors are involved in its development. The major mechanism of autoimmune liver damage involves immune reactions against host liver antigens. Numerical and functional defects of regulatory T-cells play a permissive role enabling autoimmune liver injury to occur and persist. The most typical features of AIH are female preponderance, hypergammaglobulinaemia, seropositivity for circulating autoantibodies and a picture of interface hepatitis on histology. Two types of AIH are distinguished according to serological profile: AIH type 1 patients are positive for anti-nuclear and/or anti-smooth muscle antibodies, whereas AIH type 2 patients are defined by the positivity for anti-liver kidney microsomal type 1 antibody and/or for anti-liver cytosol type 1 antibody. Clinical manifestations are variable, and AIH onset is often ill-defined, frequently mimicking acute hepatitis; its course may be fluctuating. AIH responds to immunosuppressive treatment in the majority of cases. Steroids with or without azathioprine should be instituted promptly upon diagnosis. Remission is achieved in some 80% of patients. For the remaining 20% of patients, alternative immunosuppressive agents such as mycophenolate mofetil and calcineurin inhibitors are an option. Liver transplantation should be considered for those patients who progress to cirrhosis and develop complications of end-stage liver disease, as well as for those presenting with acute liver failure; outcomes are excellent, although the disease may recur in the allograft.

Dendritic cell-CD8+ T cell communication is essential for Kinsenoside, a potential immunosuppression drug for autoimmune hepatitis

Abstract Autoimmune hepatitis (AIH) is a chronic auto-immune inflammation against liver tissue. Here, using T cell-deficient mice, acute AIH mice model and a novel AIH mice model induced by dendritic cells loaded with murine hepatocellular carcinoma cells (DC/Hepa1–6) vaccination, we reveal that Kinsenoside (KD), a major component of Anoectochilus roxburghii, has an powerful therapeutic effect on AIH by limiting the metabolism of immune cells such as DCs and CD8+ T cells, which results in the immunosuppression against autoimmune liver injury. The immunosuppressive and anti-inflammatory effect of KD is triggered by increased the expression of co-inhibitory molecules PD-L1/PD-1 to inhibit DC cross-priming of CD8+ T cell responses but not modulate the hepatotoxicity of CD8+ T cells directly. Furthermore, KD reduces immune cells metabolism and executes immunosuppressive and anti-inflammatory action by binding to the potential target VEGFR2 and blocking the cross-talk of metabolism related PI3K-AKT and inflammation related JAK2-STAT3 signaling pathways.

ДИНАМИКА ПАТОМОРФОЛОГИЧЕСКИХ ИЗМЕНЕНИЙ В ИШЕМИЗИРОВАННОМ СПИННОМ МОЗГЕ КРЫС ПОСЛЕ ЛЕЧЕНИЯ РЕКОМБИНАНТНЫМ ЭРИТРОПОЭТИНОМ (ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ)

Aim. To study how experimental autoimmune liver injury in mother influences morphofunctional features of monocyte development in the bone marrow of progeny. Materials and methods. The subjects of study were female Wistar rats with experimental liver injury and their progeny on days 30 and 60 of postnatal development divided into two groups: control and experimental. Chronic autoimmune liver injury was modeled using BCG vaccine via subcutaneous immunization with periodic intraperitoneal administration of liver antigen each three days. Results. The study showed that absolute cell count at all stages of development in the experimental group of animals decreased in comparison with the control group. Besides, the decrease was observed in PAS positive cell number, acid phosphatase activity and level of alpha-glycerophosphate dehydrogenase in monocyte series of the bone marrow and in peripheral blood monocytes of the groups of animals under observation. Conclusion. Mothers with experimental autoimmune hepatobiliary disorder give birth to progeny with disturbance expressed in functional immaturity of monocytes.

Different sites of xenoantigen delivery lead to a virally induced late‐onset hepatitis in mice through molecular mimicry

Epidemiological and laboratory evidences led to the hypothesis that molecular mimicry between viruses and self-proteins could be linked to the onset of autoimmune hepatitis (AIH). Hepatotropic viruses could be good candidates, as a pro-inflammatory environment may facilitate the development of AIH. The aims of this study were to test a virus ability to induce an AIH through molecular mimicry and the influence of hepatic inflammation in this process. C57BL/6 mice were injected i.v. or i.m. with recombinant adenoviral vectors (RecAdV) encoding for human type 2 AIH antigens to target xenoantigens expression in the liver and to create a transient hepatitis (i.v.) or for 'peripheral' xenoantigens expression (i.m.). Liver injury and B-cell response were evaluated. Late-onset hepatitis was observed 8 months after i.v. or i.m. RecAdV injections, despite presence or absence of an initial transient hepatitis. Intensity of B-cell response was similar for both type of injections, but the Ig isotypes produced were different. B-cell autoimmune response spread to several liver proteins. Liver autoimmune response can be initiated using molecular mimicry over a long period of time, validating the hit-and-run hypothesis. Initial liver inflammatory injury is neither necessary, nor detrimental to the development of AIH. These results highlight the significance of initial events on the pathogenesis of autoimmune liver injury.

Mesalamine‐induced B7‐H1 expression on hepatic stellate cells attenuates autoimmune liver injury

Hepatic stellate cells (HSCs) have immune regulatory functions. Mesalamine is an effective immune regulatory drug for inflammatory bowel disease. Thus, we hypothesized that mesalamine may also modulate the immune regulatory functions of HSCs. Since B7-H1 plays a crucial role in regulating T-cell apoptosis, we evaluated if mesalamine induces B7-H1 expression on HSCs, and if so, whether mesalamine attenuates autoimmune liver injury in vivo. LX-2 cells, an immortalized human HSC cell line, and human peripheral T-cells were used in this study. B7-H1 expression on LX-2 cells following mesalamine treatment was examined by using flow cytometry. Cell viability was analyzed by MTS assay. Concanavalin-A (ConA) mice hepatitis model was used for in vivo study. Flow cytometry showed that mesalamine treatment increased the B7-H1-expressing LX-2 cell fraction from 45.4% to 88.2%, of which increment is equivalent to that of positive control (29.9%, interferon γ-treated cells). Human T-cells incubated with LX-2 cells showed significantly less cell viability in the presence of mesalamine than cells without mesalamine treatment (P < 0.001). Histological examination revealed that hepatic necroinflammation was significantly attenuated by mesalamine pretreatment (P = 0.019), although serum levels of aminotransferases were not significantly reduced. During the 24-h period following ConA injection, 1 of 10 mice pretreated with mesalamine and 3 of 10 mice without pretreatment died. These results demonstrate that mesalamine enhances B7-H1 expression on HSCs, and thus, induces T-cell apoptosis and attenuates autoimmune liver injury.

The study on the response of Th1/Th2 cytokines to autoimmune acute liver injury in mice

The study on the response of Th1/Th2 cytokines to autoimmune acute liver injury in mice

64 ANTIGEN-SPECIFIC REGULATORY T-CELLS IN AUTOIMMUNE HEPATITIS TYPE 2: CYTOKINE PROFILE AND EFFECT OF SEMI-MATURE DENDRITIC CELLS ON SUPPRESSOR FUNCTION

Primary Biliary Cirrhosis is an autoimmune liver disease that predominantly affects middle-aged women, characterized by lymphocytic infiltration in portal tracts and destruction of intrahepatic small bile ducts, causing liver fibrosis and eventually liver failure. The histopathology is presumably mediated by CD8 T cells. Here, we describe a novel mouse model which shows gender differences similar to the female predominance observed in PBC patients. Adoptive cell transfer experiments of OVA-specific CD8+ T cells into K14-Ovap transgenic mice were performed. K14-Ovap mice express the antigenic SINFEKL peptide (residues 257–264 of OVA) under the control of human keratinocyte-specific promoter which directs expression in biliary epithelial cells. OT1 CD8+ T cells were injected intraperitoneally in male and female mice and survival rate, serum transaminases and histologic sections of the liver were analysed. Serum transaminase levels were significantly increased in female recipient mice in comparison to PBS control animals after adoptive transfer of 4×106 OT1 CD8+ T cells (**p < 0.009). In contrast transaminase levels of male mice recipient did not increase even after transfer of 10×106 OT1 CD8+ T cells. After adoptive transfer of 4×106 OT1 CD8+ T cells, histopathologic examinations of female mice showed peribiliary lymphocytic infiltrates and granuloma like lesions, whereas in male mice no histological lesions were seen. On day 6 after adoptive transfer of 20×106 and 10×106 OT1 CD8+ T cells 100% of female recipient mice died. Survival rate increased with transfer of lower cells numbers (4×106 survival rate of 80%). Male mice which received the corresponding cell numbers survived. In previously described models of PBC the immunopathology develops equally in male and female mice, in contrast to the female predominance in humans. In our model female mice showed a higher susceptibility against OT1 CD8+ T cell mediated hepatobiliary injury. We here describe an inducible, gender affected, immune-mediated model of PBC which could serve as an important tool to study gender effects on early autoimmune liver injury.

Modulation of Hepatic Fibrosis by c-Jun-N-Terminal Kinase Inhibition

c-Jun N-terminal kinase (JNK) is activated by multiple profibrogenic mediators; JNK activation occurs during toxic, metabolic, and autoimmune liver injury. However, its role in hepatic fibrogenesis is unknown. JNK phosphorylation was detected by immunoblot analysis and confocal immunofluorescent microscopy in fibrotic livers from mice after bile duct ligation (BDL) or CCl(4) administration and in liver samples from patients with chronic hepatitis C and non-alcoholic steatohepatitis. Fibrogenesis was investigated in mice given the JNK inhibitor SP600125 and in JNK1- and JNK2-deficient mice following BDL or CCl(4) administration. Hepatic stellate cell (HSC) activation was determined in primary mouse HSCs incubated with pan-JNK inhibitors SP600125 and VIII. JNK phosphorylation was strongly increased in livers of mice following BDL or CCl(4) administration as well as in human fibrotic livers, occurring predominantly in myofibroblasts. In vitro, pan-JNK inhibitors prevented transforming growth factor (TGF) beta-, platelet-derived growth factor-, and angiotensin II-induced murine HSC activation and decreased platelet-derived growth factor and TGF-beta signaling in human HSCs. In vivo, pan-JNK inhibition did not affect liver injury but significantly reduced fibrosis after BDL or CCl(4). JNK1-deficient mice had decreased fibrosis after BDL or CCl(4), whereas JNK2-deficient mice displayed increased fibrosis after BDL but fibrosis was not changed after CCl(4). Moreover, patients with chronic hepatitis C who displayed decreased fibrosis in response to the angiotensin receptor type 1 blocker losartan showed decreased JNK phosphorylation. JNK is involved in HSC activation and fibrogenesis and represents a potential target for antifibrotic treatment approaches.

Genomics of Liver Fibrosis and Cirrhosis

Hepatic fibrosis is the response to chronic injury from viral, toxic, metabolic, cholestatic, or autoimmune liver injury. However, only a minority of affected individuals develop advanced fibrosis or cirrhosis, suggesting that modifiers determine the individual risk. Aside from well-established progression factors including gender, duration of exposure to the disease, and ethnicity, unknown host genetic factors are likely to influence disease progression and prognosis. Potential genetic susceptibility loci are single nucleotide polymorphisms in fibrosis-associated genes, point mutations, microsatellites, and haplotype blocks composed of genes pivotal for fibrosis development. However, the study of complex polygenetic diseases poses numerous pitfalls in contrast to the elucidation of monogenetic (i.e., Mendelian) diseases. Many publications on the role of certain genetic variants in modulating the progression of hepatic fibrosis have been limited by inadequate study design and low statistical power. At present, powerful research strategies are being developed that allow the application of knowledge derived from the successful sequencing of the human genome that will help to translate our newly acquired insight into practical improvements for research activities and medical practice.

HCV core expression in hepatocytes protects against autoimmune liver injury and promotes liver regeneration in mice†

Hepatitis C virus (HCV) infection causes acute and chronic liver disease often leading to liver cirrhosis and hepatocellular carcinoma. Numerous studies have shown that despite induction of virus specific immunity, a curative response is often not attained; this has led to the hypothesis that HCV genes modulate immunity, thereby enabling chronic infections. This study examined the effects on immune-mediated liver injury in transgenic mice expressing core protein throughout the body and bone marrow chimeras expressing core protein in either the lymphoid compartment or liver parenchyma. Presence of core protein in the liver parenchyma but not in lymphoid cells protects from autoimmune hepatitis induced by mitogen concanavalin A (ConA). Consistent with this observation, core transgenic hepatocytes are relatively resistant to death induced by anti-Fas antibody and tumor necrosis factor alpha (TNFalpha). This protective effect is associated with preferential activation of signal transducer and activation of transcription factor 3 (STAT3) versus STAT1 in livers of ConA-injected animals. In agreement with this effect of core protein on the Janus kinase (JAK)-STAT signaling pathway, transgenic mice accelerate liver regeneration after partial hepatectomy but are not protected from hepatocyte death. In conclusion, HCV core inhibits STAT1 and stimulates STAT3 activation, which protects infected hepatocytes from attack by the cell-mediated immune system and promotes their proliferation.