T cell clonal expansions detected in patients with primary biliary cirrhosis express CX3CR1

Antigen-driven CD8 + T cell clonal expansion is a prominent feature of MASH in humans and mice

Background and Aims

Chronic liver disease due to metabolic dysfunction-associated steatohepatitis (MASH) is a rapidly increasing global epidemic. MASH progression is a consequence of the complex interplay between inflammatory insults and dysregulated hepatic immune responses. T lymphocytes have been shown to accumulate in the liver during MASH, but the cause and consequence of T cell accumulation in the liver remain unclear. Our study aimed to define the phenotype and T cell receptor diversity of T cells from human cirrhotic livers and an animal model of MASH to begin resolving their function in disease.

Approach and Results

In these studies, we evaluated differences in T cell phenotype in the context of liver disease we isolated liver resident T cell populations from individuals with cirrhosis and a murine model of MASH. Using both 5' single cell sequencing and flow cytometry we defined the phenotype and T cell receptor repertoire of liver resident T cells during health and disease.

Conclusions

MASH-induced cirrhosis and diet-induced MASH in mice resulted in the accumulation of activated and clonally expanded T cells in the liver. The clonally expanded T cells in the liver expressed markers of chronic antigenic stimulation, including PD1 , TIGIT and TOX . Overall, this study establishes for the first time that T cells undergo antigen-dependent clonal expansion and functional differentiation during the progression of MASH. These studies could lead to the identification of potential antigenic targets that drive T cell activation, clonal expansion, and recruitment to the liver during MASH.

Expression of E-cadherin by CD8+ T cells promotes their invasion into biliary epithelial cells

The presence of CD8+ T cells in the cytoplasm of biliary epithelial cells (BEC) has been correlated with biliary damage associated with primary biliary cholangitis (PBC). Here, we characterise the mechanism of CD8+ T cell invasion into BEC. CD8+ T cells observed within BEC were large, eccentric, and expressed E-cadherin, CD103 and CD69. They were also not contained within secondary vesicles. Internalisation required cytoskeletal rearrangements which facilitated contact with BEC. Internalised CD8+ T cells were observed in both non-cirrhotic and cirrhotic diseased liver tissues but enriched in PBC patients, both during active disease and at the time of transplantation. E-cadherin expression by CD8+ T cells correlated with frequency of internalisation of these cells into BEC. E-cadherin+ CD8+ T cells formed β-catenin-associated interactions with BEC, were larger than E-cadherin- CD8+ T cells and invaded into BEC more frequently. Overall, we unveil a distinct cell-in-cell structure process in the liver detailing the invasion of E-cadherin+ CD103+ CD69+ CD8+ T cells into BEC.

Immunologic Responses and the Pathophysiology of Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is an autoimmune liver disease with a female predisposition and selective destruction of intrahepatic small bile ducts leading to nonsuppurative destructive cholangitis. It is characterized by seropositivity of antimitochondrial antibodies or PBC-specific antinuclear antibodies, progressive cholestasis, and typical liver histologic manifestations. Destruction of the protective bicarbonate-rich umbrella is attributed to the decreased expression of membrane transporters in biliary epithelial cells (BECs), leading to the accumulation of hydrophobic bile acids and sensitizing BECs to apoptosis. A recent X-wide association study reveals a novel risk locus on the X chromosome, which reiterates the importance of Treg cells.

Identification of Immune Microenvironment Changes and the Expression of Immune-Related Genes in Liver Cirrhosis

Liver inflammation and the immune response have been recognized as critical contributors to cirrhosis pathogenesis. Immunity-related genes (IRGs) play an essential role in immune cell infiltration and immune reactions; however, the changes in the immune microenvironment and the expression of IRGs involved in cirrhosis remain unclear. CD45+ liver cell single-cell RNA (scRNA) sequencing data (GSE136103) from patients with cirrhosis were analyzed. The clusters were identified as known cell types through marker genes according to previous studies. GO and KEGG analyses among differentially expressed genes (DEGs) were performed. DEGs were screened to identify IRGs based on the ImmPort database. The protein-protein interaction (PPI) network of IRGs was generated using the STRING database. IRGs activity was calculated using the AUCell package. RNA microarray expression data (GSE45050) of cirrhosis were analyzed to confirm common IRGs and IRGs activity. Relevant regulatory transcription factors (TFs) were identified from the Human TFDB database. A total of ten clusters were obtained. CD8+ T cells and NK cells were significantly decreased in patients with cirrhosis, while CD4+ T memory cells were increased. Enrichment analyses showed that the DEGs focused on the regulation of immune cell activation and differentiation, NK-cell mediated cytotoxicity, and antigen processing and presentation. Four common TFs, IRF8, NR4A2, IKZF3, and REL were expressed in both the NK cluster and the DEGs of liver tissues. In conclusion, we proposed that the reduction of the CD8+ T cell cluster and NK cells, as well as the infiltration of CD4+ memory T cells, contributed to immune microenvironment changes in cirrhosis. IRF8, NR4A2, IKZF3, and REL may be involved in the transcriptional regulation of NK cells in liver fibrosis. The identified DEGs, IRGs, and pathways may serve critical roles in the development and progression of liver fibrosis.

Effect of LncRNA XIST on Immune Cells of Primary Biliary Cholangitis

Objective

Primary biliary cholangitis (PBC) is an autoimmune disease with significant gender difference. X chromosome inactivation (XCI) plays important roles in susceptibility to diseases between genders. This work focuses on the differences of LncRNA XIST in several defined immune cells populations as well as its effects on naive CD4+ T cells proliferation and differentiation in patients with PBC.

Methods

NKs, B cells, CD4+ T, and CD8+ T cells were separated by MicroBeads from peripheral blood mononuclear cells (PBMCs) of PBC patients and healthy control (HC). The expression levels of LncRNA XIST in these immune cells were quantified by qRT-PCR and their subcellular localized analyzed by FISH. Lentivirus were used to interfere the expression of LncRNA XIST, and CCK8 was used to detect the proliferation of naive CD4+ T cells in PBC patients. Finally, naive CD4+ T cells were co-cultured with the bile duct epithelial cells (BECs), and the effects of LncRNA XIST on the typing of naive CD4+ T cells and related cytokines were determined by qRT-PCR and ELISA.

Results

The expression levels of LncRNA XIST in NKs and CD4+ T cells in PBC patients were significantly higher than those in HC, and were primarily located at the nucleus. LncRNA XIST could promote the proliferation of naive CD4+ T cells. When naive CD4+ T cells were co-cultured with BECs, the expressions of IFN-γ, IL-17, T-bet and RORγt in naive CD4+ T cells were decreased.

Conclusion

LncRNA XIST was associated with lymphocyte abnormalities in patients with PBC. The high expression of LncRNA XIST could stimulate proliferation and differentiation of naive CD4+ T cells, which might account for the high occurrence of PBC in female.

Characteristics of serum chemokine profile in primary biliary cholangitis

Although chemokines have been believed to exert a pivotal role in pathogenesis of primary biliary cholangitis (PBC), comprehensive analysis of circulating chemokine profile in PBC has been little performed. The aim of this study is to determine serum chemokine profile and to explore its association with the development and progression of PBC. Sixty PBC patients and 30 healthy controls (HC) were enrolled. The sera were detected for 14 chemokines using multiplex immunoassay. The expression of CD3 and CD68 in the portal area of liver tissues was determined by immunohistochemistry in 6 PBC patients. The characteristics of chemokine profile in PBC were analyzed. Serum concentrations of most chemokines were higher, but TARC/CCL17, MDC/CCL22 and ENA-78/CXCL5 were lower in PBC patients than those in HC (all P < 0.05). Most of increased chemokines remained significant in both early and advanced PBC patients. PBC stage was correlated inversely with MCP-4/CCL13(r = -0.373), TARC/CCL17(r = -0.365), ENA-78/CXCL5 (r = -0.418) and I-TAC/CXCL11(r = -0.262), but positively with fractalkine/CX3CL1(r = 0.325). There were significant correlations between serum levels of IP-10/CXCL10 (r = 0.971, P = 0.001) and I-TAC/CXCL11 (r = 0.883, P = 0.020) and CD3 expression within the portal area, and between MIP-3α/CCL20 and CD68 expression within the portal area (r = 0.886, P = 0.019). In PBC patients, there were significant correlations among each other of MCP-4/CCL13, TARC/CCL17, MDC/CCL22, CTACK/CCL27, ENA-78/CXCL5, IP-10/CXCL10, I-TAC/CXCL11, excepting correlations of CTACK/CCL27 with IP-10/CXCL10 and I-TAC/CXCL11. Also, there were strong correlations among each other of CCL3/MIP-1α, CCL4/MIP-1β and IL-8/CXCL8. The only negative correlation was found in the serum between fractalkine/CX3CL1 and TARC/CCL17 (r = -0.311, P = 0.016). Serum levels of most chemokines are increasing throughout the development and progression of PBC, with the exception of chemokines, mainly attractive for neutrophil and eosinophil (e.g. ENA-78/CXCL5, MCP-4/CCL13), decreasing in advanced PBC, and of chemokines, dominantly responsible for Th2 chemotaxis (e.g. TARC/CCL17), decreasing in early PBC and associating negatively with PBC progression.

Immune Cell Trafficking to the Liver

The human liver is an organ with a diverse array of immunologic functions. Its unique anatomic position that leads to it receiving all the mesenteric venous blood, combined with its unique micro anatomy, allows it to serve as a sentinel for the body's immune system. Hepatocytes, biliary epithelial cells, Kupffer cells, stellate cells, and liver sinusoidal endothelial cells express key molecules that recruit and activate innate and adaptive immunity. Additionally, a diverse array of lymphoid and myeloid immune cells resides within and traffics to the liver in specific circumstances. Derangement of these trafficking mechanisms underlies the pathophysiology of autoimmune liver diseases, nonalcoholic steatohepatitis, and liver transplantation. Here, we review these pathways and interactions along with potential targets that have been identified to be exploited for therapeutic purposes.

Immune system and cholangiocytes: A puzzling affair in primary biliary cholangitis

Primary biliary cholangitis (PBC) is a cholestatic liver disease characterized by the destruction of the small and medium bile ducts. Its pathogenesis is still unknown. Despite the genome wide association study findings, the therapies targeting the cytokines pathway, tested so far, have failed. The concept of the biliary epithelium as a key player of the PBC pathogenesis has emerged over the last few years. It is now well accepted that the biliary epithelial cells (BECs) actively participate to the genesis of the damage. The chronic stimulation of BECs via microbes and bile changes the cell phenotype toward an active state, which, across the production of proinflammatory mediators, can recruit, retain, and activate immune cells. The consequent immune system activation can in turn damage BECs. Thus, the crosstalk between both innate and adaptive immune cells and the biliary epithelium creates a paracrine loop responsible for the disease progression. In this review, we summarize the evidence provided in literature about the role of BECs and the immune system in the pathogenesis of PBC. We also dissect the relationship between the immune system and the BECs, focusing on the unanswered questions and the future potential directions of the translational research and the cellular therapy in this area.

The challenges of primary biliary cholangitis: What is new and what needs to be done

Primary Biliary Cholangitis (PBC) is an uncommon, chronic, cholangiopathy of autoimmune origin and unknown etiology characterized by positive anti-mitochondrial autoantibodies (AMA), female preponderance and progression to cirrhosis if left untreated. The diagnosis is based on AMA- or PBC-specific anti-nuclear antibody (ANA)-positivity in the presence of a cholestatic biochemical profile, histologic confirmation being mandatory only in seronegative cases. First-line treatment is ursodeoxycholic acid (UDCA), which is effective in preventing disease progression in about two thirds of the patients. The only approved second-line treatment is obeticholic acid. This article summarizes the most relevant conclusions of a meeting held in Lugano, Switzerland, from September 23rd-25th 2018, gathering basic and clinical scientists with various background from around the world to discuss the latest advances in PBC research. The meeting was dedicated to Ian Mackay, pioneer in the field of autoimmune liver diseases. The role of liver histology needs to be reconsidered: liver pathology consistent with PBC in AMA-positive individuals without biochemical cholestasis is increasingly reported, raising the question as to whether biochemical cholestasis is a reliable disease marker for both clinical practice and trials. The urgent need for new biomarkers, including more accurate markers of cholestasis, was also widely discussed during the meeting. Moreover, new insights in interactions of bile acids with biliary epithelia in PBC provide solid evidence of a role for impaired epithelial protection against potentially toxic hydrophobic bile acids, raising the fundamental question as to whether this bile acid-induced epithelial damage is the cause or the consequence of the autoimmune attack to the biliary epithelium. Strategies are needed to identify difficult-to-treat patients at an early disease stage, when new therapeutic approaches targeting immunologic pathways, in addition to bile acid-based therapies, may be effective. In conclusion, using interdisciplinary approaches, groundbreaking advances can be expected before long in respect to our understanding of the etiopathogenesis of PBC, with the ultimate aim of improving its treatment.

Immunological abnormalities in patients with primary biliary cholangitis

Primary biliary cholangitis (PBC), an autoimmune liver disease occurring predominantly in women, is characterized by high titers of serum anti-mitochondrial antibodies (AMAs) and progressive intrahepatic cholestasis. The immune system plays a critical role in PBC pathogenesis and a variety of immune cell subsets have been shown to infiltrate the portal tract areas of patients with PBC. Amongst the participating immune cells, CD4 T cells are important cytokine-producing cells that foster an inflammatory microenvironment. Specifically, these cells orchestrate activation of other immune cells, including autoreactive effector CD8 T cells that cause biliary epithelial cell (BEC) injury and B cells that produce large quantities of AMAs. Meanwhile, other immune cells, including dendritic cells (DCs), natural killer (NK) cells, NKT cells, monocytes, and macrophages are also important in PBC pathogenesis. Activation of these cells initiates and perpetuates bile duct damage in PBC patients, leading to intrahepatic cholestasis, hepatic damage, liver fibrosis, and eventually cirrhosis or even liver failure. Taken together, the body of accumulated clinical and experimental evidence has enhanced our understanding of the immunopathogenesis of PBC and suggests that immunotherapy may be a promising treatment option. Herein, we summarize current knowledge regarding immunological abnormalities of PBC patients, with emphasis on underlying pathogenic mechanisms. The differential immune response which occurs over decades of disease activity suggests that different therapies may be needed at different stages of disease.

Chronic Autoimmune Epithelitis in Sjögren's Syndrome and Primary Biliary Cholangitis: A Comprehensive Review

Within the spectrum of autoimmune diseases, Sjögren's syndrome and primary biliary cholangitis are exemplary and can be coined as chronic epithelitis based on their frequent coexistence in clinical practice and the highly specific immune-mediated injury of the small bile ducts and the exocrine glands. The pathogenic mechanisms underlying the diseases are similar, with apoptosis being the key element leading to organ-specific immune-mediated injury directed against the small bile ducts and salivary gland epithelia, respectively along with similar epidemiological features, such as female predominance and the age of onset in the fifth decade of life. Indeed, novel insights into the pathogenesis of the diseases have been obtained in recent years, including a better definition of the role of B and T cells, particularly Th17 cells, and the mechanisms of autoantibody-mediated tissue injury, with anti-mitochondrial antibodies and SS-A/SS-B being identified as specific for primary biliary cholangitis and Sjögren's syndrome, respectively. These findings have opened the possibility to new targeted therapies, but most clinical needs remain unmet, particularly from a therapeutic standpoint where options diverge, with bile acids being the predominant treatment strategy in primary biliary cholangitis and immunomodulators being used to treat Sjögren's syndrome. Here we provide a comprehensive review of the most recent findings on the pathogenesis, clinical manifestations and therapeutic options for Sjögren's syndrome and primary biliary cholangitis, respectively, while stressing the common traits between these conditions. Our cumulative hypothesis is that similarities outnumber differences and that this may prove advantageous towards a better management of patients.

Review article: chemokines as orchestrators of autoimmune hepatitis and potential therapeutic targets

BACKGROUND

Chemokines contribute to the pathogenesis of autoimmune hepatitis by directing the migration and positioning of inflammatory and immune cells within the liver.

AIM

Describe the liver-infiltrating effector cell populations in autoimmune hepatitis, indicate the chemokines that influence their migration, describe the role of chemokines in hepatic fibrosis and identify chemokine-directed treatment opportunities.

METHODS

Studies cited in Pub Med from 1972 to 2014 for autoimmune hepatitis, chemokines in liver disease, pathogenesis of autoimmune hepatitis and chemokine therapy were selected.

RESULTS

T helper type 17 lymphocytes expressing CXCR3 and CCR6 are attracted to the liver by the secretion of CXCL9, CXCL10 and CXCL11. These cells recruit pro-inflammatory T helper type 1 lymphocytes expressing CXCR3 and CCR5 by secreting CXCL10. Resident natural killer T cells expressing CXCR6 migrate in response to the local secretion of CXCL16, and they modulate the inflammatory response. T helper type 2 lymphocytes expressing CCR4 are attracted by CCL17 and CCL22, and they dampen the expansion of pro-inflammatory cells. Regulatory T cells expressing CXCR3 are attracted by the secretion of CXCL9, and they help dampen the pro-inflammatory responses. CCL2, CCL3, CCL5, CXCL4, CXCL10 and CXCL16 promote fibrosis by activating or attracting hepatic stellate cells, and CX3CL1 may prevent fibrosis by affecting the apoptosis of monocytes.

CONCLUSIONS

Chemokines are requisites for mobilising, directing and positioning the effector cells in immune-mediated liver disease. They are feasible therapeutic targets in autoimmune hepatitis, and the evaluation of monoclonal antibodies that neutralise the pro-inflammatory ligands or designer peptides that block receptor activity are investigational opportunities.

Significance of oestrogen-related receptor γ on biliary epithelial cells in the pathogenesis of primary biliary cirrhosis

AIMS

Oestrogen has been speculated to play an important role in the pathogenesis of primary biliary cirrhosis (PBC), which mainly affects middle-aged and old-aged females because biliary epithelial cells (BECs) are known to express oestrogen receptors (ERs). Oestrogen-related receptors (ERRs) are constitutively active without oestrogen and competitively inhibit the ER-dependent effects of oestrogen. We clarified the effects of oestrogen and the significance of ERRs along with their association with the pathogenesis of cholangiopathy in PBC.

METHODS

We investigated the expression of ERs and ERRs and the apoptosis-related cell kinetics in BECs using cultured human BECs and human liver specimens.

RESULTS

Although cultured human BECs and the interlobular bile ducts in the liver expressed ERβ, in cultured BECs, oestrogen treatment did not induce significant cell proliferation but increased the expression of a negative cell proliferation regulator (14-3-3σ protein). The cultured BECs constantly expressed ERRα and ERRγ, and oestrogen downregulated the ERRγ expression. Furthermore, the ERRγ expression was determined in the intrahepatic bile ducts and was stronger in the middle-aged and old-aged females, particularly those with PBC, than in the younger females. The ERRγ ligand activated a transcription factor, SP1, and enhanced the expression of the pro-apoptotic Bcl-2 family molecules and Bcl-2 inhibitor-induced apoptosis in cultured BECs.

CONCLUSIONS

Although oestrogen downregulates the ERRγ expression, the increased ERRγ expression under oestrogen-deficient conditions increases the susceptibility to Bcl-2 family-mediated apoptosis in cultured human BECs of females, particularly those with PBC. Understanding the oestrogen-mediated cell kinetics is important for elucidating the pathogenesis of cholangiopathy in PBC.

Chemokine-chemokine receptor CCL2-CCR2 and CX3CL1-CX3CR1 axis may play a role in the aggravated inflammation in primary biliary cirrhosis

BACKGROUND AND AIMS

Senescent cells can alter local tissue environments by secretion of various senescence-associated secretory phenotypes (SASP), such as cytokines and chemokines. Given senescent biliary epithelial cells (BECs) in damaged small bile ducts in primary biliary cirrhosis (PBC) show increased expression of chemokines CCL2 and CX3CL1 as SASP, we further examined an involvement of CCL2/CCR2 and CX3CL1/CX3CR1 systems in the pathogenesis of PBC.

METHODS

We examined immunohistochemically the expression of CCR2, CX3CR1, CCL2 and CX3CL1 in livers taken from the patients with PBC (n = 45) and control livers (n = 78), such as chronic viral hepatitis (CVH; n = 39). CCR2 or CX3CR1-expressing cells were characterized by double immunofluorescence with CD3, CD4, CD8, CD56 or CD68.

RESULTS

CCR2 is expressed in round cells, epithelioid cells and dendritic cells and most CCR2-positive cells were CD68-positive. Infiltration of CCR2-positive cells in the intraepithelial layer or around small bile ducts was significantly more extensive in PBC than CVH and normal liver (p < 0.05) and was significantly correlated with the expression of CCL2 in BECs (p < 0.01). Most CX3CR1-expressing inflammatory cells were CD3-positive T cells (CD8 > CD4). Infiltration of CX3CR1-positive cells in the intraepithelial layer and around small bile ducts was significantly more extensive in PBC than control livers (p < 0.05) and was significantly correlated with the expression of CX3CL1 in BECs (p < 0.05).

CONCLUSION

CCL2 and CX3CL1 produced by senescent BECs may promote infiltration of corresponding CCR2 and CX3CR1-expressing cells and further aggravate inflammation in bile duct lesion in PBC.

Anti-CD40 ligand monoclonal antibody delays the progression of murine autoimmune cholangitis

While there have been significant advances in our understanding of the autoimmune responses and the molecular nature of the target autoantigens in primary biliary cirrhosis (PBC), unfortunately these data have yet to be translated into new therapeutic agents. We have taken advantage of a unique murine model of autoimmune cholangitis in which mice expressing a dominant negative form of transforming growth factor β receptor II (dnTGFβRII), under the control of the CD4 promoter, develop an intense autoimmune cholangitis associated with serological features similar to human PBC. CD40-CD40 ligand (CD40L) is a major receptor-ligand pair that provides key signals between cells of the adaptive immune system, prompting us to determine the therapeutic potential of treating autoimmune cholangitis with anti-CD40L antibody (anti-CD40L; MR-1). Four-week-old dnTGFβRII mice were injected intraperitoneally with either anti-CD40L or control immunoglobulin (Ig)G at days 0, 2, 4 and 7 and then weekly until 12 or 24 weeks of age and monitored for the progress of serological and histological features of PBC, including rigorous definition of liver cellular infiltrates and cytokine production. Administration of anti-CD40L reduced liver inflammation significantly to 12 weeks of age. In addition, anti-CD40L initially lowered the levels of anti-mitochondrial autoantibodies (AMA), but these reductions were not sustained. These data indicate that anti-CD40L delays autoimmune cholangitis, but the effect wanes over time. Further dissection of the mechanisms involved, and defining the events that lead to the reduction in therapeutic effectiveness will be critical to determining whether such efforts can be applied to PBC.

Liver immunology

The liver is the largest organ in the body and is generally regarded by nonimmunologists as having little or no lymphoid function. However, such is far from accurate. This review highlights the importance of the liver as a lymphoid organ. Firstly, we discuss experimental data surrounding the role of liver as a lymphoid organ. The liver facilitates tolerance rather than immunoreactivity, which protects the host from antigenic overload of dietary components and drugs derived from the gut and it is instrumental to fetal immune tolerance. Loss of liver tolerance leads to autoaggressive phenomena, which if not controlled by regulatory lymphoid populations, may lead to the induction of autoimmune liver diseases. Liver-related lymphoid subpopulations also act as critical antigen-presenting cells. The study of the immunological properties of liver and delineation of the microenvironment of the intrahepatic milieu in normal and diseased livers provides a platform to understand the hierarchy of a series of detrimental events that lead to immune-mediated destruction of the liver and the rejection of liver allografts. The majority of emphasis within this review will be on the normal mononuclear cell composition of the liver. However, within this context, we will discuss selected, but not all, immune-mediated liver disease and attempt to place these data in the context of human autoimmunity.

Autoimmunity in 2011

The mechanisms leading to the onset and perpetuation of systemic and tissue-specific autoimmune diseases are complex, and numerous hypotheses have been proposed or confirmed over the past 12 months. It is particularly of note that the number of articles published during 2011 in the major immunology and autoimmunity journals increased by 3 % compared to the previous year. The present article is dedicated to a brief review of the reported data and, albeit not comprehensive of all articles, is aimed at identifying common and future themes. First, clinical researchers were particularly dedicated to defining refractory forms of diseases and to discuss the use and switch of therapeutic monoclonal antibodies in everyday practice. Second, following the plethora of genome-wide association studies reported in most multifactorial diseases, it became clear that genomics cannot fully explain the individual susceptibility and additional environmental or epigenetic factors are necessary. Both these components were widely investigated, both in organ-specific (i.e., type 1 diabetes) and systemic (i.e., systemic lupus erythematosus) diseases. Third, a large number of 2011 works published in the autoimmunity area are dedicated to dissect pathogenetic mechanisms of tolerance breakdown in general or in specific conditions. While our understanding of T regulatory and Th17 cells has significantly increased in 2011, it is of note that most of the proposed lines of evidence identify potential targets for future treatments and should not be overlooked.

Serum autoantibodies for the diagnosis and management of autoimmune liver diseases

The spectrum of autoimmune liver diseases (AILD) includes primary biliary cirrhosis, primary sclerosing cholangitis and autoimmune hepatitis. The immunological mechanisms triggering the initiation and perpetuation of AILD remains unknown, while autoantigens are now recognized in most cases, and are generally nontraditional in their widespread distribution. Sensitive and specific methods for the detection of serum autoantibodies in patients affected by AILD represent a challenge for researchers and clinicians who desire to obtain an early and certain diagnosis as well as markers of disease control. To this regard, the use and interpretation of serum autoantibodies in AILD may be seen as paradigmatic for the large gaps in our knowledge based on the lack of true population-based studies. The present review article will critically discuss the available evidence on the use of autoantibody findings in the diagnosis or management of autoimmune liver disease.

Lymphoma-like T cell infiltration in liver is associated with increased copy number of dominant negative form of TGFβ receptor II

Hepatosplenic T cell lymphoma (HSTCL) is a distinct and lethal subtype of peripheral T cell lymphoma with an aggressive course and poor outcome despite multiagent chemotherapy. Contradictory literature, an unknown etiology, and poor response to treatment highlight the need to define the malignant process and identify molecular targets with potential for successful therapeutic interventions. Herein, we report that mice homozygously expressing a dominant negative TGFβRII (dnTGFβRII) under the control of the CD4 promoter spontaneously develop lymphoma-like T cell infiltration involving both spleen and liver. Splenomegaly, hepatomegaly and liver dysfunction were observed in homozygous dnTGFβRII mice between 10 weeks and 10 months of age associated with a predominant infiltration of CD4⁻CD8⁻TCRβ⁺NK1.1⁺ or CD8⁺TCRβ⁺NK1.1⁻ T cell subsets. Notch 1 and c-Myc expression at the mRNA levels were significantly increased and positively correlated with the cell number of lymphoid infiltrates in the liver of dnTGFβRII homozygous compared to hemizygous mice. Further, 2×10⁴ isolated lymphoma-like cells transplant disease by adoptive cell transfers. Collectively, our data demonstrate that increased copy number of dnTGFβRII is critical for development of lymphoma-like T cell infiltration.

Recent advances in understanding the pathogenesis of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic progressive cholestatic autoimmune liver disease characterized by the destruction of small intrahepatic bile ducts and the presence of highly specific serum antimitochondrial antibodies (AMAs). The human leukocyte antigen (HLA) gene has been proved to have strongest association with PBC susceptibility, and non-HLA genes, including IL12A, IL12RB2, STAT4, IRF5-TNPO3, ORMDL3/IKZF3, MMEL1, SPIB, CTLA-4, FCRL3 and A2BP1, are also closely associated with PBC susceptibility. Four AMAs including anti-M2, anti-M4, anti-M8 and anti-M9, and antinuclear antibodies (ANAs), such as antinuclear dot antibodies (SP100, PML, NDP52, SP140), antinuclear pore antibodies (gp210, p62), antinuclear envelope antibodies (Lamin and Lamin B receptor), and anti-centromere antibodies, may also be involved in the pathogenesis of PBC. The imbalance between Th17 cells and regulatory T lymphocytes (Treg) may also play an important role in the pathogenesis of PBC. In addition, senescence, autophagy, apoptosis of biliary epithelial cells (BECs), and environmental factors, such as Epstein-Barr virus (EBV) infection and smoking, may also contribute to the pathogenesis of PBC. Understanding of the mechanisms responsible for the pathogenesis of PBC has important implications for the treatment of PBC.

Xenobiotics and autoimmunity: does acetaminophen cause primary biliary cirrhosis?

The serologic hallmark of primary biliary cirrhosis (PBC) is the presence of antimitochondrial autoantibodies (AMAs) directed against the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2). The PBC-related autoepitope of PDC-E2 contains lipoic acid, and previous work has demonstrated that mimics of lipoic acid following immunization of mice lead to a PBC-like disease. Furthermore, approximately one-third of patients who have ingested excessive amounts of acetaminophen (paracetamol) develop AMA of the same specificity as patients with PBC. Quantitative structure-activity relationship (QSAR) data indicates that acetaminophen metabolites are particularly immunoreactive with AMA, and we submit that in genetically susceptible hosts, electrophilic modification of lipoic acid in PDC-E2 by acetaminophen or similar drugs can facilitate a loss of tolerance and lead to the development of PBC.

Autoimmune hepatitis type 2 associated with an unexpected and transient presence of primary biliary cirrhosis-specific antimitochondrial antibodies: a case study and review of the literature

Background

Unlike other autoimmune liver diseases, primary biliary cirrhosis (PBC) has never been reported in early childhood, while type 2 autoimmune hepatitis (AIH) is eminently a paediatric disease.

Case presentation

We describe a case of type 2 AIH with serological positivity for PBC-specific anti-mitochondrial antibodies (AMA) in a 3-year old girl. We found this observation intriguing as AMA and indeed an overlap with PBC are virtually absent in Type 2 AIH, a pediatric form of AIH which is distinct precisely because it is characterized by pathognomonic anti-liver kidney microsomal type 1 (LKM-1) showing a remarkable antigen-specificity directed against cytochrome P4502D6. We also review the literature in relation to AMA positivity in paediatric age and adolescence. In our case, the presence of AIH-2-specific anti-LKM-1 and PBC-specific AMA was confirmed by indirect immunofluorescence (IIF), and immunoblotting and ELISA based on recombinant mitochondrial antigens. The clinical, laboratory and histological features of the child are given in detail. Interestingly the mother was AMA positive without other features of PBC. The child was successfully treated with immunosuppression and five years after the original diagnosis is on a low dose of prednisolone and azathioprine, with no signs of relapse. Anti-LKM-1 antibodies are still present in low titres. AMA were detectable for the first 4 years after the diagnosis and disappeared later.

Conclusion

This is the first case report in the literature of AIH type 2 with an unexpected PBC-specific AMA positivity in a young child. Response to immunosuppressive treatment was satisfactory and similar to that described in AIH. A review of published reports on AMA positivity in paediatric age shows that the antibody may arise in the context of immunodeficiency and is variably associated with liver damage.

Biosensors for immune cell analysis-A perspective

Massively parallel analysis of single immune cells or small immune cell colonies for disease detection, drug screening, and antibody production represents a "killer app" for the rapidly maturing microfabrication and microfluidic technologies. In our view, microfabricated solid-phase and flow cytometry platforms of the future will be complete with biosensors and electrical/mechanical/optical actuators and will enable multi-parametric analysis of cell function, real-time detection of secreted signals, and facile retrieval of cells deemed interesting.

Sercarzian immunology--In memoriam. Eli E. Sercarz, 1934-2009

During his long career as a principal investigator and educator, Eli Sercarz trained over 100 scientists. He is best known for developing hen egg white lysozyme (HEL) as a model antigen for immunologic studies. Working in his model system Eli furthered our understanding of antigen processing and immunologic tolerance. His work established important concepts of how the immune system recognizes antigenic determinants processed from whole protein antigens; specifically he developed the concepts of immunodominance and crypticity. Later in his career he focused more on autoimmunity using a variety of established animal models to develop theories on how T cells can circumvent tolerance induction and how an autoreactive immune response can evolve over time. His theory of "determinant spreading" is one of the cornerstones of our modern understanding of autoimmunity. This review covers Eli's entire scientific career outlining his many seminal discoveries.

Primary biliary cirrhosis and Sjögren's syndrome: autoimmune epithelitis

Primary biliary cirrhosis (PBC) has been often coined a model autoimmune disease based on the homogeneity amongst patients, the frequency and similarity of antimitochondrial antibodies, including the highly directed immune response to pyruvate dehydrogenase (PDC-E2). A significant number of patients with PBC suffer from sicca and amongst these, there are patients who also have classic Sjögren's syndrome. Indeed, both PBC and Sjögren's syndrome are characterized by inflammation of target epithelial elements. Both diseases can be considered on the basis of a number of other related clinical aspects, including proposed unique apoptotic features of the target tissue, the role of secretory IgA, and the frequency with which both diseases overlap with each other. Indeed, PBC may be considered a Sjögren's syndrome of the liver, whereas Sjögren's syndrome can be equally discussed as PBC of the salivary glands. Dissection of the genetic predispositions for both diseases and especially the molecular basis of effector mechanisms, will become critical elements in developing new therapies.