INTRODUCTION:Primary sclerosing cholangitis (PSC) is a rare chronic cholestatic disease with heterogeneous phenotypes that may lead to liver transplantation and/or end-stage liver disease. Its multifactorial etiopathogenesis remains uncertain, but gut-liver axis and bile composition and excretion are widely demonstrated to influence the immune-mediated fibrogenic reactive cascade.AREAS COVERED:Different experimental therapeutic options are under investigation, mainly aiming at modulating bile acids excretion, limiting inflammatory-cascade reactions, and changing intestinal microbiota composition; none of them yet demonstrated to prolong transplant-free survival.This review provides a comprehensive description of the experimental drugs recently tested and/or currently under investigation. A bibliographical search was performed in PubMed, MEDLINE, EMBASE, OVID, and clinicaltrial.gov until July 2021.EXPERT OPINION:The heterogeneity and poor prevalence of PSC, its uncertain pathophysiology, and the lack of surrogate endpoints are the major challenges in drug discovery. Strategies that synergistically target microbiota, bile acids, and liver fibrosis are needed. In parallel, we must enhance biomarkers discovery to develop surrogate endpoints, as biochemical markers' fluctuations over the time hamper their effectiveness. Magnetic resonance cholangiopancreatography tools that accurately measure bile duct changes represent a potential marker for disease monitoring. A collaboration between academia, research consortia, patient's associations, and industry is required.

Receptor activator of nuclear factor-kappa B (RANK) is a member of the tumor necrosis factor alpha (TNFα) superfamily of cytokines; its only known ligand is RANKL, and their interaction triggers re...

Microbial cells significantly outnumber human cells in the body, and the microbial flora at mucosal sites are shaped by environmental factors and, less intuitively, act on host immune responses, as demonstrated by experimental data in germ-free and gnotobiotic studies. Our understanding of this link stems from the established connection between infectious bacteria and immune tolerance breakdown, as observed in rheumatic fever triggered by Streptococci via molecular mimicry, epitope spread and bystander effects. The availability of high-throughput techniques has significantly advanced our capacity to sequence the microbiome and demonstrated variable degrees of dysbiosis in numerous autoimmune diseases, including rheumatoid arthritis, type 1 diabetes, multiple sclerosis and autoimmune liver disease. It remains unknown whether the observed differences are related to the disease pathogenesis or follow the therapeutic and inflammatory changes and are thus mere epiphenomena. In fact, there are only limited data on the molecular mechanisms linking the microbiota to autoimmunity, and microbial therapeutics is being investigated to prevent or halt autoimmune diseases. As a putative mechanism, it is of particular interest that the apoptosis of intestinal epithelial cells in response to microbial stimuli enables the presentation of self-antigens, giving rise to the differentiation of autoreactive Th17 cells and other T helper cells. This comprehensive review will illustrate the data demonstrating the crosstalk between intestinal microbiome and host innate and adaptive immunity, with an emphasis on how dysbiosis may influence systemic autoimmunity. In particular, a gut-liver axis involving the intestinal microbiome and hepatic autoimmunity is elucidated as a paradigm, considering its anatomic and physiological connections.

Tick-borne diseases (TBDs) are emerging and reemerging diseases transmitted by ticks, which portray wide heterogeneity and global distribution. TBDs may present acute clinical pictures that resemble those of autoimmune diseases (i.e., musculoskeletal symptoms, cutaneous involvement, neurologic impairment, renal failure, etc.), and in some cases infection is considered a triggering factor for autoimmunity (e.g., rheumatoid arthritis, autoimmune thyroid disease, vasculitides). The clinician should consider TBDs among the differential diagnoses when approaching autoimmune-like signs in areas of tick infestation. Epidemiological setting (e.g., endemic areas, seasons) and an accurate diagnostic approach (i.e., clinical history, physical examination and laboratory tests) are necessary to confirm TBDs. Further, control and prevention of TBDs is warranted. Research in the fields of ticks microbiome and vaccination (i.e., wildlife and humans) are ahead to control vector transmission and bacterial infection. This review offers a comprehensive update on TBDs and their relationship with autoimmunity.

Introduction: Guillain-Barre syndrome is the most common cause of acute flaccid paralysis worldwide. Microorganisms such as Campylobacter jejuni, Cytomegalovirus, Epstein-Barr virus, Mycoplasma pneumoniae, Haemophilus influenzae and Zika virus have been linked to the disease. The most common clinical variants are acute inflammatory demyelinating polyneuropathy and acute motor axonal neuropathy. Plasma exchange and intravenous immunoglobulins are the standard therapy for the disease.Areas covered: research to elucidate the pathophysiology of Guillain-Barre syndrome has led to the development of drugs directed towards new potential therapeutic targets. This review offers a comprehensive view of the current treatment based upon the physiopathology.Expert opinion: patients with Guillain-Barre syndrome need a multidisciplinary approach, limitation to walk unaided and disability score are indicators for treatment as well as the presence of autonomic dysfunction and pain. Admission to intensive care units should be considered for those patients presenting with respiratory failure, bulbar involvement and progression of the disease. Research aimed to deciphering the pathophysiology of the disease, discovering new biomarkers and establishing algorithms of prediction of both the disease and its outcomes is warranted.

Autoimmune Polyglandular Syndrome type 1 (APS-1) is a subtype of the autoimmune polyendocrine syndrome characterized by the simultaneous or sequential dysfunction of multiple endocrine or non-endocrine glands. A clinical diagnosis of APS-1 is typically based on the presence of at least two of three following criteria: chronic mucocutaneous candidiasis, hypoparathyroidism and adrenal insufficiency. The first identified causative mutated gene for APS-1 is autoimmune regulator (AIRE) encoding a critical transcription factor, which is primarily expressed in the medullary thymic epithelial cells (mTECs) for generating central immune tolerance. A wide range of chronic, debilitating complications, with no obvious correlation with genetics, makes a diagnosis of APS-1 challenging early in the disease course. Managing APS-1 is difficult due to its complexity, especially the intricate relationships within manifestations and genetic mutations. The past decades have witnessed dramatic progress in elucidating the function of AIRE and conducting large-scale cohort studies in APS-1. However, no clear evidence-based guidelines have been established in APS-1. In this review, we provide a detailed critical overview of the study history, epidemiology, clinical features, and related mechanisms of autoimmunity in APS-1, as well as currently available therapies for this autoimmune disorder.

Myeloid cells play a major role in the sensitization to liver injury, particularly in chronic inflammatory liver diseases with a biliary or hepatocellular origin, and the interplay between myeloid cells and the liver may explain the increased incidence of hepatic osteodystrophy. The myeloid cell-liver axis involves several mature myeloid cells as well as immature or progenitor cells with the complexity of the liver immune microenvironment aggravating the mist of cell differentiation. The unique positioning of the liver at the junction of the peripheral and portal circulation systems underlines the interaction of myeloid cells and hepatic cells and leads to immune tolerance breakdown. We herein discuss the scenarios of different chronic liver diseases closely modulated by myeloid cells and illustrate the numerous potential targets, the understanding of which will ultimately steer the development of solid immunotherapeutic regimens. Ultimately, we are convinced that an adequate modulation of the liver microenvironment to modify the functional and quantitative characteristics of myeloid cells will be a successful approach to treating chronic liver diseases of different etiologies.

Guillain–Barré syndrome (GBS) and transverse myelitis (TM) both represent immunologically mediated polyneuropathies of major clinical importance. Both are thought to have a genetic predisposition, but as of yet no specific genetic risk loci have been clearly defined. Both are considered autoimmune, but again the etiologies remain enigmatic. Both may be induced via molecular mimicry, particularly from infectious agents and vaccines, but clearly host factor and co-founding host responses will modulate disease susceptibility and natural history. GBS is an acute inflammatory immune-mediated polyradiculoneuropathy characterized by tingling, progressive weakness, autonomic dysfunction, and pain. Immune injury specifically takes place at the myelin sheath and related Schwann-cell components in acute inflammatory demyelinating polyneuropathy, whereas in acute motor axonal neuropathy membranes on the nerve axon (the axolemma) are the primary target for immune-related injury. Outbreaks of GBS have been reported, most frequently related to Campylobacter jejuni infection, however, other agents such as Zika Virus have been strongly associated. Patients with GBS related to infections frequently produce antibodies against human peripheral nerve gangliosides. In contrast, TM is an inflammatory disorder characterized by acute or subacute motor, sensory, and autonomic spinal cord dysfunction. There is interruption of ascending and descending neuroanatomical pathways on the transverse plane of the spinal cord similar to GBS. It has been suggested to be triggered by infectious agents and molecular mimicry. In this review, we will focus on the putative role of infectious agents as triggering factors of GBS and TM.

Primary biliary cholangitis (PBC), formerly called primary biliary cirrhosis, is a chronic cholestatic disease characterized by an autoimmune-mediated destruction of small and medium-sized intrahepatic bile ducts. Originally PBC was considered to be rare and almost invariably fatal, mainly because the diagnosis was made in patients presenting with advanced symptomatic disease (jaundice and decompensated cirrhosis). However, the development of a reproducible indirect immunofluorescence assay for antimitochondrial antibody made it possible to diagnose the disease at an earlier stage, and introduction of ursodeoxycholic acid therapy as the first-line therapy for PBC drastically changed PBC-related mortality. At present, patients with an early histological stage have survival rates similar to those of an age- and sex-matched control population. Although 30% of patients treated with ursodeoxycholic acid may exhibit incomplete responses, obeticholic acid and drugs currently in development are expected to be effective for these patients and improve outcomes. Meanwhile, more etiology and immunopathology studies using new technologies and novel animal models are needed to dissect variances of clinical course, treatment response, and outcome in each patient with PBC. Precision medicine that is individualized for each patient on the basis of the cause identified is eagerly awaited.

Immunoglobulin G4-related disease (IgG4-RD) is a recently described systemic inflammatory disease characterized by increased serum IgG4 concentrations, lymphoplasmacytic infiltrations, storiform fibrosis, and obliterative phlebitis. However, although IgG4-RD has become increasingly recognized, the number of patients with IgG4-RD remains unclear. Data from several studies indicate that patients who have a T-helper type 2 (Th2-) dominant immune response, which leads to the hyperproduction of Th2 cytokines, then progress to IgG4-RD. Glucocorticoids are the most common treatment for IgG4-RD and generally, patients have a good response-a characteristic of IgG4-RD. However, relapses during the tapering of glucocorticoid therapy are common. Second-line therapy after glucocorticoids includes immunosuppressant agents. Although the long-term outcome still remains unclear, there is increased interest in the relationships between IgG-RD and malignancies. In this review, the authors provide a detailed overview of the geoepidemiology, pathogenesis, diagnostic features, treatment, and prognosis of IgG4-RD.

Tattoos are defined as the introduction of exogenous pigments into the dermis in order to produce a permanent design. This process may occur unintentional or may be deliberately administered for cosmetic or medical reasons. Tattoos have been around for over 5000 years and over time have evolved to represent a common cosmetic practice worldwide. Currently, adverse reactions are relatively rare and generally unpredictable and predominantly include immune-mediated reactions and skin infections. Along with better healthcare standards and more stringent public health mandates such as the provision of disposable needles, major infectious complications related to hepatitis and human retroviral infections have decreased significantly. When they do occur, skin infections are most frequently associated with Staphylococcus aureus or Streptococcus pyogenes. The aim of this study is to review the types and rates of medical complications of permanent tattoos. PubMed search and search dates were open ended. Acute local inflammation is the most common complication, but infections, allergic contact dermatitis, and other inflammatory or immune responses that are not well-characterized may occur. As many patients with immune reactions to tattoos do not react on skin or patch testing, it is postulated that the antigens contained in dyes or pigments are such small molecules that they need to be haptenized in order to become immunogenic. Red ink is associated more frequently with long-term reactions, including granulomatous and pseudolymphomatous phenomena or morphea-like lesions and vasculitis. Exacerbation of preexisting psoriasis, atopic dermatitis, and pyoderma gangrenosum may occur after tattooing. There is no well-defined association between cancer and tattoos. The treatment of tattoo-related complications may include local destructive measures (cryotherapy, electro-surgery, dermabrasion, chemical destruction, ablative laser destruction), surgical excision, and thermolysis of the pigment using Q-switched laser therapy.

The functions of macrophages that lead to effective host responses are critical for protection against Staphylococcus aureus. Deep tissue-invading S. aureus initially countered by macrophages trigger macrophage accumulation and induce inflammatory responses through surface receptors, especially toll-like receptor 2 (TLR2). Here, we found that macrophages formed sporadic aggregates in the liver during infection. Within those aggregates, macrophages co-localized with T cells and were indispensable for their infiltration. In addition, we have focused on the mechanisms underlying the polarization of macrophages in Forkhead box transcription factor O1 (FoxO1) conditional knockout Lys (Cre/+) FoxO1 (fl/fl) mice following S. aureus infection and report herein that macrophage M1-M2 polarization via TLR2 is intrinsically regulated by FoxO1. Indeed, for effective FoxO1 activity, stimulation of TLR2 is essential. However, following S. aureus challenge, there was a decrease in macrophage FoxO1, with increased phosphorylation of FoxO1 because of TLR2-mediated activation of PI3K/Akt and c-Raf/MEK/ERK pathway. Following infection in Lys (Cre/+) FoxO1 (fl/fl) mice, mice became more susceptible to S. aureus with reduced macrophage aggregation in the liver and attenuated Th1 and Th17 responses. FoxO1 abrogation reduced M1 pro-inflammatory responses triggered by S. aureus and enhanced M2 polarization in macrophages. In contrast, overexpression of FoxO1 in macrophages increased pro-inflammatory mediators and functional surface molecule expression. In conclusion, macrophage FoxO1 is critical to promote M1 polarization and maintain a competent T cell immune response against S. aureus infection in the liver. FoxO1 regulates macrophage M1-M2 polarization downstream of TLR2 dynamically through phosphorylation.

In most autoimmune diseases the serologic hallmarks of disease precede clinical pathology by years. Therefore, the use of animal models in defining early disease events becomes critical. We took advantage of a “designer” mouse with dysregulation of interferon gamma (IFNγ) characterized by prolonged and chronic expression of IFNγ through deletion of the IFNγ 3′‐untranslated region adenylate uridylate‐rich element (ARE). The ARE‐Del‐/‐ mice develop primary biliary cholangitis (PBC) with a female predominance that mimics human PBC that is characterized by up‐regulation of total bile acids, spontaneous production of anti‐mitochondrial antibodies, and portal duct inflammation. Transfer of CD4 T cells from ARE‐Del‐/‐ to B6/Rag1‐/‐ mice induced moderate portal inflammation and parenchymal inflammation, and RNA sequencing of liver gene expression revealed that up‐regulated genes potentially define early stages of cholangitis. Interestingly, up‐regulated genes specifically overlap with the gene expression signature of biliary epithelial cells in PBC, implying that IFNγ may play a pathogenic role in biliary epithelial cells in the initiation stage of PBC. Moreover, differentially expressed genes in female mice have stronger type 1 and type 2 IFN signaling and lymphocyte‐mediated immune responses and thus may drive the female bias of the disease. Conclusion: Changes in IFNγ expression are critical for the pathogenesis of PBC. (Hepatology 2016;64:1189‐1201)

Herein we will review the role of glycans in the immune system. Specific topics covered include: the glycosylation sites of IgE, IgM, IgD, IgE, IgA, and IgG; how glycans can encode "self" identity by functioning as either danger associated molecular patterns (DAMPs) or self-associated molecular patterns (SAMPs); the role of glycans as markers of protein integrity and age; how the glycocalyx can dictate the migration pattern of immune cells; and how the combination of Fc N-glycans and Ig isotype dictate the effector function of immunoglobulins. We speculate that the latter may be responsible for the well-documented association between alterations of the serum glycome and autoimmunity. Due to technological limitations, the extent of these autoimmune-associated glycan alterations and their role in disease pathophysiology has not been fully elucidated. Thus, we also review the current technologies available for glycan analysis, placing an emphasis on Multiple Reaction Monitoring (MRM), a rapid high-throughput technology that has great potential for glycan biomarker research. Finally, we put forth The Altered Glycan Theory of Autoimmunity, which states that each autoimmune disease will have a unique glycan signature characterized by the site-specific relative abundances of individual glycan structures on immune cells and extracellular proteins, especially the site-specific glycosylation patterns of the different immunoglobulin(Ig) classes and subclasses.

To the Editor: Primary biliary cirrhosis (PBC) is considered to be an autoimmune disorder. When not adequately responding to medical treatment, PBC often progresses to liver cirrhosis, necessitating liver transplantation.1 This constitutes a need for the development of animal models, both to unravel pathogenetic pathways and to test innovative therapeutic agents. Gershwin and his group have greatly contributed to this endeavor and in their most recent and intriguing manuscript successfully test a novel therapeutic approach in a well-established PBC model.2 In humans, antimitochondrial antibodies (AMAs, especially anti–PDC-E2) are the diagnostic hallmark of PBC.3 Accordingly, AMAs are being used to define PBC-like disease also in mice,4 even though alterations in serum liver tests or histological changes are sometimes minimal. In our view, however, use of AMAs to define PBC in mice is potentially misleading when insufficiently quantified. Using recombinant PDC-E2170-313,6 we established an enzyme-linked immunosorbent assay (ELISA) to quantify AMA reactivity in mouse and human serum, determining the half maximal effective concentration. We found significantly increased AMAs in dnTgfβ-R2 mice, a proposed PBC mouse model, at 3 months of age, in line with previous reports.4 However, their AMA titer was only 3.6-fold increased compared with wild-type littermates (Fig. 1A,B). In contrast, AMA reactivity in sera of human PBC patients was more than 2,500-fold increased compared with age-matched healthy controls (Fig. 1C,D). Subsequently, we studied AMA reactivity in a cohort of 24 wild-type female C57Bl/6 mice by comparing optical density in single dilutions (1:1,000) and found a significant increase with age from 0.35 ± 0.11 to 0.55 ± 0.30 and 1.05 ± 0.72 (optical density) at 3, 6, and 12 months of age, respectively (Fig. 1E). This age dependency was not found in a cohort of 116 female human controls (Fig. 1F). We conclude from these observations that (1) AMAs do not adequately define PBC-like disease in mice, (2) other immunologic and histologic features of PBC must instead be carefully evaluated in PBC models, and (3) the value of purely AMA-based PBC animal models to test therapeutic compounds should be re-evaluated. Anti–PDC-E2 signals of sera from (A) dnTgfβ-R2 mice (n = 14) and wild-type littermates (n = 7) and (C) PBC patients (n = 15) and healthy controls (n = 14) were determined following stepwise dilution with phosphate-buffered saline by ELISA. The half maximal effective concentration (EC50) was calculated from these titration curves for precise quantification of anti-AMA reactivity (B and D). *P < 0.05 (analysis of variance). Applying single dilutions (1:1,000), anti-PDC-E2 signals of (E) wild-type mice (n = 24) and (F) healthy human females (n = 116) were determined by ELISA, and optical density (OD) was correlated with age. *P < 0.05 (analysis of variance). Simon Hohenester M.D. Ulrich Beuers M.D. Juan F. Medina M.D., Ph.D. Ronald P. Oude Elferink Ph.D. Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands Division of Gene Therapy and Hepatology, CIMA, and School of Medicine, University of Navarra and Ciberehd, Pamplona, Spain

Allergy to penicillin is the most commonly reported antibiotic allergy. However, most patients who report a positive history of a prior reaction to penicillin are not found to be allergic to penicillin upon skin testing. Often, this history is vague or based on a parent's recollection of an event that occurred in the distant past. Avoidance of penicillin based on self-reported allergic history alone often leads to the use of an alternate antibiotic with greater cost or side effect profile. Patients with a negative skin test to both major and minor determinants may generally be given penicillin, with a statistical risk of developing an allergic reaction similar to that observed in the general population. A more cautious approach in these cases where the degree of suspicion is low, an allergic etiology is unproven, or there is a negative skin test, is to do a graded challenge. If the skin test is positive, an alternate antibiotic should be used. If, however, an alternate antibiotic is not available, then desensitization may be performed, but there are limitations to desensitization as well, and tolerance is not permanent. Avoidance of cephalosporins may be recommended in cases of penicillin allergy, but newer generation cephalosporins have demonstrate less cross-reactivity to penicillin than earlier generation ones. Desensitization protocols for cephalosporins are available but not standardized. The mechanisms of antibiotic sensitization are not clearly understood.

The pathophysiology of non-traumatic osteonecrosis is more complex than that of traumatic osteonecrosis, and corticosteroid-induced osteonecrosis presents the greatest challenge because of the multiple effects of corticosteroids on multi-system pathways; these pathways include the effects of corticosteroids on osteoblast differentiation, osteoblast and osteoclast apoptosis, lipid metabolism, coagulation pathways, and calcium metabolism. These pathways are frequently interrelated with each other, which makes the pathogenesis even more difficult to understand. Host factors and underlying disease have been shown to play a significant role in the risk of developing osteonecrosis, and our understanding of the pathogenesis must be able to explain why some patients are at greater risk than others. Identification of genetic variants that convey additional risk will also help to personalize the way we deliver care, both in the prevention and treatment of osteonecrosis. Further understanding of the intricate immunologic and genetic pathways contributing to osteonecrosis is at the forefront of research and may soon lead to viable and less invasive non-surgical therapeutic strategies.

Amyloidosis is defined as the extracellular accumulation at systemic or organ-specific level of insoluble low molecular weight protein fibrils manifesting a beta pleated sheet configuration and a characteristic staining pattern. Several different types of proteins may lead to this phenomenon, and amyloidosis is defined by the biochemical nature of the protein in the deposits and further classified according to whether the deposits are localized or systemic, acquired or inherited, and by the resulting clinical phenotype. Amyloidosis includes subtypes such as light chain, associated with serum amyloid A protein, heritable and familial forms, dialysis-related disease, and organ-specific conditions. The pathogenesis and clinical features of these clinical and pathological entities will be critically discussed in this review article.

Cholestatic liver disorders are caused by genetic defects, mechanical aberrations, toxins, or dysregulations in the immune system that damage the bile ducts and cause accumulation of bile and liver tissue damage. They have common clinical manifestations and pathogenic features that include the responses of cholangiocytes and hepatocytes to injury. We review the features of bile acid transport, tissue repair and regulation, apoptosis, vascular supply, immune regulation, and cholangiocytes that are associated with cholestatic liver disorders. We now have a greater understanding of the physiology of cholangiocytes at the cellular and molecular levels, as well as genetic factors, repair pathways, and autoimmunity mechanisms involved in the pathogenesis of disease. These discoveries will hopefully lead to new therapeutic approaches for patients with cholestatic liver disease.

The critical function of the immune system is to discriminate self from non-self. Tolerance against self-antigens is a highly regulated process and, in order to maintain it, the immune system must be able to distinguish self-reactive lymphocytes as they develop. The presence of autoantibodies is the consequence of breakdown of tolerance and, although they are an important serological feature of autoimmune diseases, their presence is not exclusive of these conditions. Antibodies against self-antigens are also found in cancer, during massive tissue damage and even in healthy subjects. Natural autoantibodies provide immediate protection against infection and also prevent inflammation by facilitating the clearance of oxidized lipids, oxidized proteins, and apoptotic cells; their role in development of autoimmunity is still unclear. Detection of serum autoantibodies in clinical practice has become more available to clinicians worldwide while providing a powerful diagnostic tool. This review discusses the clinical significance of autoantibodies, their pathogenic mechanisms in autoimmune diseases and, finally, illustrates the technology available for appropriate autoantibody detection.