Environmental basis of primary biliary cholangitis.

Autoimmunity is a consequence of both genetic and environmental factors, occurring in genetically susceptible hosts with environmental triggers. While genome-wide association studies have revealed a number of susceptible genes contributing to etiology, the environmental triggers remain poorly understood. Primary biliary cholangitis, formally known as primary biliary cirrhosis, is considered a model autoimmune disease for which our group has extensively evaluated environmental factors involved in its etiology. Bacterial infection and xenobiotics have been proposed as candidate environmental factors that may explain tolerance breakdown and production of primary biliary cholangitis-specific antimitochondrial autoantibodies. Large-scale case-control studies have consistently detected an association of primary biliary cholangitis with urinary tract infections caused by Escherichia coli, as E. coli PDC-E2 is molecularly similar to human PDC-E2, the immunodominant target of AMAs. Another bacterium of interest is Novosphingobium aromaticivorans, a ubiquitous xenobiotic-metabolizing bacterium that produces lipoylated proteins, which are highly reactive with sera from primary biliary cholangitis patients. Regarding xenobiotics, case-control studies have suggested that frequent use of nail polish is associated with an increased susceptibility to primary biliary cholangitis. We found that 2-octynamide, the conjugate derived from 2-octynoic acid present in cosmetics, lipsticks, and some chewing gums, was unique in both its quantitative structure-activity relationship analysis and reactivity with primary biliary cholangitis sera. 2-nonyamide is another xenobiotic that also has the optimal chemical structure for xenobiotic modification of the PDC-E2 epitope, as demonstrated by the enhanced epitope recognition with AMA-positive PBC sera. Moreover, we found that C57BL/6 mice immunized with 2-octynoic acid-BSA possess many of the features characteristic to primary biliary cholangitis. Impact statement Autoimmunity is believed to develop in genetically susceptible hosts with triggers from the environment. Researchers have recently demonstrated that bacteria and xenobiotics commonly present in our environment are potential triggers of tolerance breakdown against autoantigens and autoimmunity, particularly in primary biliary cholangitis (PBC). The link between xenobiotics and PBC has been further confirmed with the establishment of PBC model mice by immunizing mice with xenobiotics.

Diagnosis of fish and shellfish allergies.

Seafood allergy is a hypersensitive disorder with increasing prevalence worldwide. Effective and accurate diagnostic workup for seafood allergy is essential for clinicians and patients. Parvalbumin and tropomyosin are the most common fish and shellfish allergens, respectively. The diagnosis of seafood allergies is complicated by cross-reactivity among fish allergens and between shellfish allergens and other arthropods. Current clinical diagnosis of seafood allergy is a complex algorithm that includes clinical assessment, skin prick test, specific IgE measurement, and oral food challenges. Emerging diagnostic strategies, such as component-resolved diagnosis (CRD), which uses single allergenic components for assessment of epitope specific IgE, can provide critical information in predicting individualized sensitization patterns and risk of severe allergic reactions. Further understanding of the molecular identities and characteristics of seafood allergens can advance the development of CRD and lead to more precise diagnosis and improved clinical management of seafood allergies.

Proteomic analysis reveals distinctive protein profiles involved in CD8+ T cell-mediated murine autoimmune cholangitis.

Autoimmune cholangitis arises from abnormal innate and adaptive immune responses in the liver, and T cells are critical drivers in this process. However, little is known about the regulation of their functional behavior during disease development. We previously reported that mice with T cell-restricted expression of a dominant negative form of transforming growth factor beta receptor type II (dnTGFßRII) spontaneously develop an autoimmune cholangitis that resembles human primary biliary cholangitis (PBC). Adoptive transfer of CD8+ but not CD4+ T cells into Rag1-/- mice reproduced the disease, demonstrating a critical role for CD8+ T cells in PBC pathogenesis. Herein, we used SOMAscan technology to perform proteomic analysis of serum samples from dnTGFßRII and B6 control mice at different ages. In addition, we analyzed CD8 protein profiles after adoptive transfer of splenic CD8+ cells into Rag1-/- recipients. The use of the unique SOMAscan aptamer technology revealed critical and distinct profiles of CD8 cells, which are key to biliary mediation. In total, 254 proteins were significantly increased while 216 proteins were significantly decreased in recipient hepatic CD8+ cells compared to donor splenic CD8+ cells. In contrast to donor splenic CD8+ cells, recipient hepatic CD8+ cells expressed distinct profiles for proteins involved in chemokine signaling, focal adhesion, T cell receptor and natural killer cell-mediated cytotoxicity pathways.

Toward solving the etiological mystery of primary biliary cholangitis.

Primary biliary cholangitis (PBC) is considered a model autoimmune disease due to its signature AMA autoantibody, female predominance and relatively specific portal infiltration and cholestasis. The identification and cloning of the major mitochondrial autoantigens, recognized by AMA, have served as an immunologic platform to identify the earliest events involved in loss of tolerance. Despite the relative high concordance rate in identical twins, genome wide association studies have not proven clinically useful and have led to suggestions of epigenetic events. To understand the natural history and etiology of PBC, several murine models have been developed including spontaneous models, models induced by chemical xenobiotic immunization and by "designer" mice with altered interferon metabolism. Herein, we describe five such models including 1) NOD.c3c4 mice, 2) dominant negative form of transforming growth factor (TGF)-ß receptor type II (dnTGFßRII) mice, 3) interleukin (IL)-2Rα-/- mice 4) ARE Del-/-mice and 5) 2-octynoic acid conjugated bovine serum albumin (2OA-BSA) immunized mice. Individually there is no perfect murine model but collectively the models point to loss of tolerance to PDC-D2, the major mitochondrial autoantigen, as the earliest event that occurs before clinical disease is manifest. Although there is no direct association of AMA titer and PBC disease progression it is noteworthy that the triad of PBC monocytes, biliary apotopes and AMA leads to an intense proinflammatory cytokine burst. Further the recurrence of PBC after liver transplantation indicates that, due to MHC restriction, disease activity must include not only adaptive immunity but also innate immune mechanisms. We postulate that successful treatment of PBC may require a personalized approach with therapies designed for different stages of disease.

Screening and identification of mimotopes of the major shrimp allergen tropomyosin using one-bead-one-compound peptide libraries.

The one-bead-one-compound (OBOC) combinatorial peptide library is a powerful tool to identify ligand and receptor interactions. Here, we applied the OBOC library technology to identify mimotopes specific to the immunoglobulin E (IgE) epitopes of the major shellfish allergen tropomyosin. OBOC peptide libraries with 8-12 amino acid residues were screened with serum samples from patients with shellfish allergy for IgE mimotopes of tropomyosin. Twenty-five mimotopes were identified from the screening and their binding reactivity to tropomyosin-specific IgE was confirmed by peptide ELISA. These mimotopes could be divided into seven clusters based on sequence homology, and epitope mapping by EpiSearch of the clustered mimotopes was performed to characterize and confirm the validity of mimotopes. Five out of six of the predicted epitopes were found to overlap with previously identified epitopes of tropomyosin. To further confirm the mimicry potential of mimotopes, BALB/c mice were immunized with mimotopes conjugated to keyhole limpet hemocyanin and assayed for their capacity to induce tropomyosin-specific antibodies. BALB/c mice that received mimotope immunization were found to have an elevated level of tropomyosin-specific immunoglobulin G, but not mice that received an irrelevant mimotope. This study pioneers the successful application of the OBOC libraries using whole sera to screen and identify multiple shrimp allergen mimotopes and validates their mimicry potential using in vitro, in vivo, and in silico methods.Cellular & Molecular Immunology advance online publication, 14 september 2015; doi:10.1038/cmi.2015.83.

The modulation of co-stimulatory molecules by circulating exosomes in primary biliary cirrhosis.

Exosomes are nanoparticles of endocytic origin, secreted by a myriad of cell populations that are attracting increased attention by virtue of their ability to modulate cell-to-cell communications. They are also attracting attention in a variety of immunological issues, including autoimmunity and, in particular, their ability to regulate cytokine and chemokine activation. Primary biliary cirrhosis (PBC) is considered a model autoimmune disease, which has a highly focused cytotoxic response against biliary epithelial cells. We have isolated exosomes from plasma from 29 patients with PBC and 30 healthy controls (HCs), and studied the effect of these exosomes on co-stimulatory molecule expression and cytokine production in mononuclear cell populations using an ex vivo system. We also identified the microRNA (miRNA) populations in PBC compared to HC exosomes. We report herein that although exosomes do not change cytokine production, they do significantly alter co-stimulatory molecule expression on antigen-presenting populations. Further, we demonstrated that CD86 up-regulated expression on CD14+ monocytes, whereas CD40 up-regulated on CD11c+ dendritic cells by exosomes from patients with PBC. In addition, there were differences of miRNA expression of circulating exosomes in patients with PBC. These data have significant importance based on observations that co-stimulatory molecules play a differential role in the regulation of T-cell activation. Our observation indicated that aberrant exosomes from PBC selectively induce expression of co-stimulatory molecules in different subset of antigen-presenting cells. These alterations may involve in pathogenesis of autoimmune liver disease.Cellular & Molecular Immunology advance online publication, 21 September 2015; doi:10.1038/cmi.2015.86.

Adaptive immunity in the liver.

The anatomical architecture of the human liver and the diversity of its immune components endow the liver with its physiological function of immune competence. Adaptive immunity is a major arm of the immune system that is organized in a highly specialized and systematic manner, thus providing long-lasting protection with immunological memory. Adaptive immunity consists of humoral immunity and cellular immunity. Cellular immunity is known to have a crucial role in controlling infection, cancer and autoimmune disorders in the liver. In this article, we will focus on hepatic virus infections, hepatocellular carcinoma and autoimmune disorders as examples to illustrate the current understanding of the contribution of T cells to cellular immunity in these maladies. Cellular immune suppression is primarily responsible for chronic viral infections and cancer. However, an uncontrolled auto-reactive immune response accounts for autoimmunity. Consequently, these immune abnormalities are ascribed to the quantitative and functional changes in adaptive immune cells and their subsets, innate immunocytes, chemokines, cytokines and various surface receptors on immune cells. A greater understanding of the complex orchestration of the hepatic adaptive immune regulators during homeostasis and immune competence are much needed to identify relevant targets for clinical intervention to treat immunological disorders in the liver.

Extrahepatic malignancies in primary biliary cirrhosis: a comparative study at two European centers.

Limited information and divergent results are available on the prevalence/incidence, survival, and risk factors for developing extrahepatic malignancies (EMs) in primary biliary cirrhosis (PBC). The aim of the study was to analyze the epidemiology and survival rates for EM in PBC patients. The study was conducted on two series of patients followed up at two European centers (361 in Padova, Italy, and 397 in Barcelona, Spain) for a mean 7.7 ± 7 and 12.2 ± 7 years, respectively. The cancer incidence was compared with the standardized incidence ratios (SIRs) calculated using the Cancer Registry of the Veneto Region (Italy) and the Cancer Registry of Tarragona (Spain). Seventy-two patients developed EM. The prevalence of cases was similar in Padova (9.7 %) and Barcelona (9.4 %). The overall cancer incidence was similar to the expected incidence for the general population in the same geographical area (SIR = 1.2), and so was the crude EM rate (855.01 vs 652.86 per 100,000 patient-years, respectively, RR = 1.3). Logistic regression analysis showed that advanced histological stage and extrahepatic autoimmune diseases were significantly associated with the onset of EM. Survival was similar for PBC patients with and without EM (p = n.s.), and actual survival was similar to the one predicted by the Mayo model. The incidence of EM in PBC patients was found similar in Italy and Spain and no different from that of the general population. Advanced histological stage and extrahepatic autoimmune disease were risk factors significantly associated with EM developing in PBC. The onset of cancer in PBC patients does not influence the natural history of their liver disease.

Tropomyosin Is the Major Mollusk Allergen: Reverse Transcriptase Polymerase Chain Reaction, Expression and IgE Reactivity.

The complementary DNAs encoding tropomyosins of the abalone Haliotis diversicolor, the scallop Chlamys nobilis, and the mussel Perna viridis were amplified by reverse transcriptase polymerase chain reaction and thereafter cloned in plasmid vectors for expression. Immunoblot analysis showed that recombinant proteins of abalone, scallop, and mussel tropomyosin were reactive to serum IgE antibodies from subjects allergic to shellfish but not to nonallergic controls. Nucleotide and amino acid sequences of abalone, scallop, and mussel tropomyosins are highly similar (mostly > 55%) to those of crustacean allergens identified as tropomyosins. Absorption experiments showed that recombinant tropomyosins from the 3 mollusks were able to remove serum IgE reactivity against the 38-kDa tropomyosin of the organisms. These results demonstrate that tropomyosin is the major allergen among various common edible mollusks. Yet a comparison between the amino acid sequences of putative epitopes in crustaceans and mollusks suggests that the epitopes in the two groups may be distinct. Parsimony analysis of the nucleotide sequences of tropomyosin from different mollusks suggests that the tropomyosin gene sequence is a useful tool for phylogenetic analysis of this group of animals.