B cell targeted therapy in autoimmunity

Systems biology and artificial intelligence analysis highlights the pleiotropic effect of IVIg therapy in autoimmune diseases with a predominant role on B cells and complement system

Intravenous immunoglobulin (IVIg) is used as treatment for several autoimmune and inflammatory conditions, but its specific mechanisms are not fully understood. Herein, we aimed to evaluate, using systems biology and artificial intelligence techniques, the differences in the pathophysiological pathways of autoimmune and inflammatory conditions that show diverse responses to IVIg treatment. We also intended to determine the targets of IVIg involved in the best treatment response of the evaluated diseases. Our selection and classification of diseases was based on a previously published systematic review, and we performed the disease characterization through manual curation of the literature. Furthermore, we undertook the mechanistic evaluation with artificial neural networks and pathway enrichment analyses. A set of 26 diseases was selected, classified, and compared. Our results indicated that diseases clearly benefiting from IVIg treatment were mainly characterized by deregulated processes in B cells and the complement system. Indeed, our results show that proteins related to B-cell and complement system pathways, which are targeted by IVIg, are involved in the clinical response. In addition, targets related to other immune processes may also play an important role in the IVIg response, supporting its wide range of actions through several mechanisms. Although B-cell responses and complement system have a key role in diseases benefiting from IVIg, protein targets involved in such processes are not necessarily the same in those diseases. Therefore, IVIg appeared to have a pleiotropic effect that may involve the collaborative participation of several proteins. This broad spectrum of targets and 'non-specificity' of IVIg could be key to its efficacy in very different diseases.

Nanoparticle-based non-viral CRISPR delivery for enhanced immunotherapy

The CRISPR Cas9 system has received considerable attention due to its simplicity, efficiency, and high precision for gene editing. The development of various therapeutic applications of the CRISPR system is under active research. In particular, its proven effects and promise in immunotherapy are of note. CRISPR/Cas9 components can be transported in various forms, such as plasmid DNA, mRNA of the Cas9 protein with gRNA, or a ribonucleoprotein complex. Even with its proven gene editing superiority, there are limitations in delivering the CRISPR system to target cells. CRISPR systems can be delivered via physical methods, viral vectors, or non-viral carriers. The development of diverse types of nanoparticles that could be used as non-viral carriers could overcome the disadvantages of physical techniques and viral vectors such as low cell viability, induction of immune response, limited loading capacity, and lack of targeting ability. Herein, we review the recent developments in applications of CRISPR system-mediated non-viral carriers in immunotherapy, depending on the targeting cell types, and discuss future research directions.

The emerging role of complement in neuromuscular disorders

The complement cascade is a key arm of the immune system that protects the host from exogenous and endogenous toxic stimuli through its ability to potently regulate inflammation, phagocytosis, and cell lysis. Due to recent clinical trial successes and drug approvals for complement inhibitors, there is a resurgence in targeting complement as a therapeutic approach to prevent ongoing tissue destruction in several diseases. In particular, neuromuscular diseases are undergoing a recent focus, with demonstrated links between complement activation and disease pathology. This review aims to provide a comprehensive overview of complement activation and its role during the initiation and progression of neuromuscular disorders including myasthenia gravis, amyotrophic lateral sclerosis, and Duchenne muscular dystrophy. We will review the preclinical and clinical evidence for complement in these diseases, with an emphasis on the complement-targeting drugs in clinical trials for these indications.

The modified vaccination technique designed to prevent and cure acute and chronic disorders

In spite of enormous efforts there have been no solutions to date for preventing/terminating certain acute and chronic disorders of humans by vaccination or drugs. Yet it is well understood that if the target antigen (ag) could be presented appropriately to the cells of the immune system then solutions could be found. Recently, the Barabas research group has introduced and described the third vaccination method - called modified vaccination technique (MVT) - which has the ability to provide a corrective immune response in experimental animals with an autoimmune kidney disease. Injections of immune complexes - made up of the target ag and specific non-pathogenic IgM antibodies directed against the target ag - achieved downregulation of pathogenic immune responses and tolerance to self was regained. Utilizing the immune system's natural abilities to respond to corrective information, the MVT technique was able to prevent an autoimmune kidney disease from occurring (prophylactic effect) in experimental animals, and when present, terminating it (therapeutic effect) specifically and without measurable side effects.It is predicted that the application of the MVT will have the potential in the future to revolutionize the preventative and therapeutic options for dealing with chronic disorders in humans (such as autoimmune disease, cancer and acute chronic infections) and achieve cures.

Antibody-initiated beneficial and harmful immune responses

A critical function of the immune system is to maintain tolerance to self by corrective immune responses throughout life, including preventing or correcting changes that may interfere with organ function and architectural integrity. These changes have two broad categories, namely (1) exogenous antigen-induced mishaps (e.g., due to bacterial, viral or fungal infections) and (2) endogenous antigen-caused ailments initiated by modified self-antigens derived from damaged organs following exposure to smoke, certain drugs, chemicals, infectious agents, radiation, etc., resulting in autoimmune diseases or cancer. In some cases, cells of the immune system are unable to respond with a corrective antibody response. For example, presentation of a modified self-antigen can initiate a pathogenic IgG immune response, thereby causing an autoimmune disease. Furthermore, if cancer-associated antigens are not appropriately presented to the cells of the immune system, there is failure to mount a specific pathogenic lytic IgG autoantibody response for recognition and elimination of cancer-associated antigens, and as a consequence, the cancer continues to proliferate.The third vaccination technique that we have developed and designated a modified vaccination technique (MVT) is able to correct these immunological mishaps. The premise of the MVT is that it can prevent both exogenous (infectious and contagious diseases) and endogenous (autoimmune diseases and cancer) antigen-caused diseases, as well as terminate established diseases. Therefore, by exploiting the immune system's natural abilities to make corrective responses, it has both prophylactic and therapeutic actions, with minimal side effects.

Tolerance, loss of tolerance and regaining tolerance to self by immune-mediated events

Autoimmunity has both beneficial and harmful aspects. Beneficial aspects include: (1) removal of released intracytoplasmic antigens (ags) (cells at the end of their life span or damaged by outside agents) by specific nonpathogenic IgM autoantibodies and mononuclear cells and (2) recognition and elimination of cancerous cells. In contrast, harmful aspects include: (1) mounting a pathogenic autoimmune response against a tissue-derived ag, a 'modified self,' resulting in autoimmune disease and (2) inability to recognize and eliminate a cancerous clone. The immune system continuously faces internal and external influences; however, even when it is compromised or overwhelmed, it will still endeavor to regain and maintain tolerance to self. To promote this, we developed a 'modified vaccination technique' (MVT) (described as the third vaccination method after active and passive immunizations). It has two components: purified exogenous/endogenous ag (i.e., target ag) and a high-titer-specific antibody (ab) against the target ag made into an immune complex (IC) with predetermined immune-inducing components. The MVT works by ab information transfer (production of same class of immunoglobulin with the same specificity against the target ag that is present in the vaccine), thereby re-establishing tolerance to self (caused by exogenous/endogenous ags) following repeated administration of appropriate ICs. This vaccination technique can be used both prophylactically and therapeutically, and it mimics the immune system's natural abilities to respond to corrective information specifically, rapidly, safely and with minimal side effects and makes this approach a novel solution for many disorders that are difficult or impossible to cure or manage.

Cyclic Peptides for Effective Treatment in a Long-Term Model of Graves Disease and Orbitopathy in Female Mice

A model for human Graves disease in mice was used to compare several treatment approaches. The mice received regular adenovirus (Ad) thyroid-stimulating hormone receptor (TSHR) A subunit immunizations (injections every 4 weeks). The generation of anti-TSHR antibodies, enlarged thyroid sizes (goiter), elevated serum thyroxine levels, retro-orbital fibrosis, and cardiac involvement (tachycardia and hypertrophy) were consistently observed over 9 months. Treatment of established disease in these mice using cyclic peptides that mimic one of the cylindrical loops of the TSHR leucine-rich repeat domain improved or cured all investigated parameters after six consecutive monthly injections. The first significant beneficial effects were observed 3 to 4 months after starting these therapies. In immunologically naïve mice, administration of any of the cyclic peptides did not induce any immune response. In contrast, monthly injections of the full antigenic TSHR A domain as fusion protein with immunoglobulin G crystallizable fragment induced clinical signs of allergy in Ad-TSHR-immunized mice and anti-TSHR antibodies in naïve control mice. In conclusion, cyclic peptides resolved many clinical findings in a mouse model of established Graves disease and orbitopathy. In contrast to blocking TSHR by allosteric modulation, the approach does not incur a direct receptor antagonism, which might offer a favorable side effect profile.

Review of Mouse Models of Graves' Disease and Orbitopathy-Novel Treatment by Induction of Tolerance

Various approaches have been used to model human Graves' disease in mice, including transfected fibroblasts, and plasmid or adenoviral immunisations with the extracellular A subunit of the human thyrotropin receptor (TSHR). Some of these models were only observed for a short time period or were self-limiting. A long-term model for human Graves' disease was established in mice using continuing immunisations (4-weekly injections) with recombinant adenovirus expressing TSHR. Generation of TSHR binding cAMP-stimulatory antibodies, thyroid enlargement and alterations, elevated serum thyroxin levels, tachycardia and cardiac hypertrophy were maintained for at least 9 months in all Ad-TSHR-immunised mice. Here, we show that these mice suffer from orbitopathy, which was detected by serial orbital sectioning and histomorphometry. Attempts to treat established Graves' disease in preclinical mouse model studies have included small molecule allosteric antagonists and specific antagonist antibodies which were isolated from hypothyroid patients. In addition, novel peptides have been conceived which mimic the cylindrical loops of the TSHR leucine-rich repeat domain, in order to re-establish tolerance toward the antigen. Here, we show preliminary results that one set of these peptides improves or even cures all signs and symptoms of Graves' disease in mice after six consecutive monthly injections. First beneficial effects were observed 3-4 months after starting these therapies. In immunologically naïve mice, administration of the peptides did not induce any immune response.

Refractory necrotizing scleritis successfully treated with adalimumab

Necrotizing scleritis is the most severe and destructive form of scleritis with vision-threatening sequelae. It is divided into with inflammation and without inflammation (scleromalacia perforans). Adalimumab is a tumour necrosis factor (TNF)-inhibiting anti-inflammatory medication licensed for the treatment of rheumatoid and psoriatic arthritis, ankylosing spondylitis and inflammatory bowel disease (in the USA). We report two cases of necrotizing scleritis successfully treated with adalimumab.

Can rituximab induce long-term disease remission in patients with intra-ocular non-infectious inflammation?

Treatment of non-infectious uveitis is based primarily on the use of systemic corticosteroids and second-line immunosuppressive drugs. However, their extensive side effect profile, particularly for steroids, has led to the increased use of other immunosuppressive drugs, as sparing capacity agents. Rituximab is an anti-CD20 chimeric antibody, often given as a single course of 2 infusions, resulting in complete depletion of peripheral mature B cells. While it is licensed to treat refractory systemic lymphoma patients, it has also shown promising results in systemic auto-immune diseases, where a single course of treatment is able to achieve long-term clinical remission. Treatment with rituximab has been reported for various ocular conditions, suggesting it may be effective in inducing long-term disease control and other systemic immunosuppressive agents can be reduced or discontinued. When disease relapse occurs, a further course or courses can be given with good results. This review summarizes the current evidence regarding the role of rituximab in treating non-infectious uveitis.

Immunopathological events initiated and maintained by pathogenic IgG autoantibodies in an experimental autoimmune kidney disease

The experimental models of Heymann nephritis (HN) and slowly progressive Heymann nephritis (SPHN) give us rare opportunities to investigate the etiologies and pathogenesis of two immunopathological processes in rats leading to: (1) autoimmune disease, where the autoimmune disease HN and SPHN is initiated and maintained by cross-reactive pathogenic IgG autoantibodies (aabs) directed against the renal proximal convoluted tubules' brush border (BB) cells - where the nephritogenic antigen (ag) is produced and localized - damaging and releasing BB associated nephritogenic ag into the circulation which in turn contributes to continuation of the autoimmune disease; and (2) immune complex glomerulonephritis, where the glomerular injury is initiated, proceeding into a chronic progressive disease by depositing immune complexes (ICs) - made up of a glomerular epithelial cell produced endogenous nephritogenic ag and the developing pathogenic IgG aab directed against the nephritogenic ag, and complement components - on the epithelial side of the glomerular basement membrane. We also observed how the normally functioning immune system is able to avert autoimmune disease developments by circulating specific non-pathogenic IgM aabs clearing the system of intracytoplasmic ags released from cells at the end of their life spans or following damage by toxic agents. We also described how an autoimmune disease SPHN can be prevented and when present terminated by the implementation of a new vaccination technique we have developed and call modified vaccination technique. By increasing the specific IgM aab production against the native nephritogenic ag - by injecting ICs made up of: [nephritogenic ag X homologous anti-nephritogenic ag IgM ab] in slight ag excess into SPHN rats - pathogenic IgG aab producing native and modified nephritogenic ags were removed from the circulation and termination of the autoimmune disease causing immune events was achieved. Even though HN and SPHN are not well-known disease models, their studies are important because the etiologies and pathogenesis of two conditions - that can also occur in humans, namely autoimmune diseases and membranous glomerulonephritis - can be simultaneously investigated.

Anti-CD 20 monoclonal antibody (rituximab) treatment for inflammatory ocular diseases

Rituximab is a monoclonal antibody directed against the CD20 antigen expressed on B cells and widely used in the treatment of non-Hodgkin's lymphoma and rheumatoid arthritis. There is a growing amount of literature which suggests that rituximab may be useful for inflammatory ocular diseases and intraocular lymphoma. Few cases have been reported on treatment of refractory scleritis, peripherative ulcerative keratitis, uveitis and ocular surface inflammatory disorders. Rituximab may be effective in the treatment of ocular inflammatory diseases in particular the most aggressive, recalcitrant and sight-threatening forms of inflammation such as uveitis associated to juvenile idiopathic arthritis. We review the literature covering the use of Rituximab in these conditions and report our results on the efficacy of Rituximab in the treatment of 8 children with very severe and long-standing uveitis who failed to respond to one or more TNF blockers. Our patients showed improvement in activity of uveitis, reduction of concomitant corticosteroids and immunosuppressants after a mean follow-up time of 14.87 months on rituximab. No serious adverse events were encountered in our treated patients. Although further studies are needed for assessing the efficacy of rituximab and the exact dosing regimen, rituximab may be considered as a treatment alternative in patients with the most aggressive forms of inflammatory ocular diseases who fail to respond to conventional and anti-TNF immunosuppressive agents.

Activation-induced cytidine deaminase and aberrant germinal center selection in the development of humoral autoimmunities

Humoral immunity, which is the branch of the immune system governed by B cells, protects the body from extracellular pathogens through the secretion of immunoglobulins. Given the unpredictability of exogenous antigens, B cells must be accommodating to numerous genetic alterations to mold immunoglobulin specificity to recognize offending pathogens. Abnormalities in this process leave the host susceptible to permanent pathological modifications and in particular humoral autoimmunities in which secreted immunoglobulins mistake host proteins as pathogenic targets. Underlying the development of self-reactive immunoglobulins is activation-induced cytidine deaminase (AID), a mutagenic enzyme responsible for modifying the specificity of B cells by producing point mutations at the immunoglobulin gene locus. Ideally, these mutations result in an increased affinity for exogenous antigens. However, in pathological scenarios, these mutations produce or enhance a B cell's ability to target the host. AID-induced mutations occur in the germinal center microenvironment of peripheral lymphoid tissue, where pathogenic B-cell clones must evade overwhelming selection pressures to be released systemically. Recent research has revealed numerous genes and pathways responsible for eliminating self-reactive clones within the germinal center. On the basis of these studies, this review aims to clarify the link between AID and the generation of pathogenic immunoglobulins. Furthermore, it describes the selective pressures that pathogenic B cells must bypass within the germinal center to secrete immunoglobulins that ultimately result in disease.

Bortezomib delays the onset of factor VIII inhibitors in experimental hemophilia A, but fails to eliminate established anti-factor VIII IgG-producing cells

BACKGROUND

Replacement therapy with exogenous factor VIII to treat hemorrhages induces inhibitory anti-FVIII antibodies in up to 30% of patients with hemophilia A. Current approaches to eradicate FVIII inhibitors using high-dose FVIII injection protocols (immune tolerance induction) or anti-CD20 depleting antibodies (Rituximab) demonstrate limited efficacy; they are extremely expensive and/or require stringent compliance from the patients.

OBJECTIVES

To investigate whether the proteasome inhibitor bortezomib, which depletes plasmocytes, modulates the anti-FVIII immune response in FVIII-deficient mice.

METHODS AND RESULTS

Preventive 4-week treatment of naïve mice with bortezomib at the time of FVIII administration delayed the development of inhibitory anti-FVIII IgG, and depleted plasma cells as well as different lymphoid cell subsets. Conversely, curative treatment of inhibitor-positive mice for 10 weeks, along with FVIII administration, failed to eradicate FVIII inhibitors to extents that would be clinically relevant if achieved in patients. Accordingly, bortezomib did not eradicate anti-FVIII IgG-secreting plasmocytes that had homed to survival niches in the bone marrow, despite significant elimination of total plasma cells.

CONCLUSIONS

The data suggest that strategies for the efficient reduction of anti-FVIII IgG titers in patients with hemophilia A should rely on competition for survival niches for plasmocytes in the bone marrow rather than the mere use of proteasome inhibitors.

Distinct in vitro binding properties of the anti-CD20 small modular immunopharmaceutical 2LM20-4 result in profound and sustained in vivo potency in cynomolgus monkeys

Objectives. To characterize the in vitro binding and effector function properties of CD20-directed small modular immunopharmaceutical (SMIP) 2LM20-4, and to compare its in vivo B-cell depletion activity with the mutated 2LM20-4 P331S [no in vitro complement-dependent cytotoxicity (CDC)] and rituximab in cynomolgus monkeys.

Methods. Direct binding is examined in flow cytometry, confocal microscopy, scatchard and lipid raft assays. Effector function assays include CDC and Fc-mediated cellular toxicity. In the 6-month-long in vivo B-cell depletion study, single i.v. dosages of 1 or 10 mg/kg of anti-CD20 proteins were administered to monkeys and B-cell counts were monitored in peripheral blood, bone marrow and lymph nodes.

Results. 2LM20-4 has lower saturation binding to human primary B cells and recruits fewer CD20 molecules into lipid rafts compared with rituximab; however, it induces higher in vitro CDC. In competitive binding, 2LM20-4 only partially displaces rituximab, suggesting that it binds to a fraction of CD20 molecules within certain locations of the plasma membrane as compared with rituximab. In monkeys, 2LM20-4 had more sustained B-cell depletion activity than rituximab in peripheral blood and had significantly more profound and sustained activity than 2LM20-4 P331S and rituximab in the lymph nodes.

Conclusions. SMIP 2LM20-4, which binds to a fraction of CD20 molecules as compared with rituximab, has more potent in vitro CDC, and more potent and sustained B-cell depletion activity in cynomolgus monkeys. Our work has considerable clinical relevance since it provides novel insights related to the emerging B-cell depletion therapies in autoimmune diseases.

Therapeutic targeting of B cells for rheumatic autoimmune diseases

Autoreactive B cells are characterized by their ability to secrete autoantibodies directed against self-peptides. During the last decade, it has become increasingly apparent that B lymphocytes not only produce autoantibodies but also exert important regulatory roles independent of their function as antibody-producing cells. This is especially relevant in the context of autoimmunity, because autoreactive B cells have been shown to possess the ability to activate pathogenic T cells, to produce pro-inflammatory cytokines, and to promote the formation of tertiary lymphoid tissue in target organs. The production of monoclonal antibodies against B-cell-surface molecules has facilitated the characterization of several distinct B lymphocyte subsets. These cell-surface molecules have not only served as useful cell differentiation markers but have also helped to unravel the important biological functions of these cells. Some of these molecules, all of which are expressed on the cell surface, have proven to be effective therapeutic targets. In both animal models and in clinical assays, the efficient elimination of B lymphocytes has been shown to be useful in the treatment of rheumatoid arthritis and other autoimmune diseases. The treatment of most rheumatic autoimmune diseases relies mainly on the use of cytotoxic immunosuppressants and corticosteroids. Although this has resulted in improved disease survival, patients may nonetheless suffer severe adverse events and, in some cases, their relapse rate remains high. The increasing need for safer and more effective drugs along with burgeoning new insights into the pathogenesis of these disorders has fueled interest in biological agents; clinical trials involving the B-cell depletion agent rituximab have been especially promising. This article reviews the current knowledge of B-cell biology and pathogenesis as well as the modern therapeutic approaches for rheumatic autoimmune diseases focusing in particular on the targeting of B-cell-specific surface molecules and on the blocking of B-cell activation and survival.

Murine visceral leishmaniasis: IgM and polyclonal B-cell activation lead to disease exacerbation

In visceral leishmaniasis, the draining LN (DLN) is the initial site for colonization and establishment of infection after intradermal transmission by the sand fly vector; however, little is known about the developing immune response within this site. Using an intradermal infection model, which allows for parasite visceralization, we have examined the ongoing immune responses in the DLN of BALB/c mice infected with Leishmania infantum. Although not unexpected, at early times post-infection there is a marked B-cell expansion in the DLN, which persists throughout infection. However, the characteristics of this response were of interest; as early as day 7 post-infection, polyclonal antibodies (TNP, OVA, chromatin) were observed and the levels appeared comparable to the specific anti-leishmania response. Although B-cell-deficient JhD BALB/c mice are relatively resistant to infection, neither B-cell-derived IL-10 nor B-cell antigen presentation appear to be primarily responsible for the elevated parasitemia. However, passive transfer and reconstitution of JhD BALB/c with secretory immunoglobulins, (IgM or IgG; specific or non-specific immune complexes) results in increased susceptibility to L. infantum infection. Further, JhD BALB/c mice transgenetically reconstituted to secrete IgM demonstrated exacerbated disease in comparison to WT BALB/c mice as early as 2 days post-infection. Evidence suggests that complement activation (generation of C5a) and signaling via the C5a receptor (CD88) is related to the disease exacerbation caused by IgM rather than cytokine levels (IL-10 or IFN-gamma). Overall these studies indicate that polyclonal B-cell activation, which is known to be associated with human visceral leishmaniasis, is an early and intrinsic characteristic of disease and may represent a target for therapeutic intervention.

Environmental factors and the induction of autoimmunity in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic cholestatic disease with an autoimmune pathogenesis and an unknown etiology, predominantly affecting postmenopausal women. The term PBC is a misnomer since most cases currently diagnosed have limited probability to develop cirrhosis. Antimitochondrial autoantibodies, elevated IgM and selective destruction of the intrahepatic bile ducts are the hallmarks of PBC. A permissive genetic background is critical in producing susceptibility despite limited associations with alleles within the MHC. The disease has incomplete concordance in monozygotic twins and its geoepidemiology suggests a role for environmental factors in the induction of PBC. This hypothesis is further supported by clinical (risk factors) and experimental evidence. Some of the factors incriminated model molecular mimicry by infectious agents and xenobiotic chemicals. Additional candidates are being proposed through large screening; all proposed associations ultimately require confirmation in animal models and clinical practice.

Effect of complement and its regulation on myasthenia gravis pathogenesis

Myasthenia gravis (MG) is primarily caused by antibodies directed towards the skeletal muscle acetylcholine receptor, leading to muscle weakness. Although these antibodies may induce compromise of neuromuscular transmission by blocking acetylcholine receptor function or antigenic modulation, the predominant mechanism of injury to the neuromuscular junction is complement-mediated lysis of the postsynaptic membrane. The vast majority of data to support the role of complement derives from experimentally acquired MG (EAMG). In this article, we review studies that demonstrate the central role of complement in EAMG and MG pathogenesis along with the emerging role of complement in T- and B-cell function, as well as the potential for complement inhibitor-based therapy to treat human MG.

Immunotherapy of autoimmune diabetes by nasal administration of tandem glutamic acid decarboxylase 65 peptides

Mucosally induced tolerance is an attractive strategy for immunotherapy of autoimmune diseases. Treatment of nonobese diabetic (NOD) mice with a mixture of autoantigen peptides is better geared toward slowing the progression of late stage type 1 diabetes (T1D) than treatment with any of the peptides alone. In this study, we constructed a fusion protein CTB-GADIII. It contains cholera toxin B subunit (CTB) and three tandem peptides derived from glutamic acid decarboxylase 65 (GAD65), p217-236, p524-538 and p290-306. The purified renatured pentamer fusion protein was effective in inhibiting the development of diabetes in NOD mice when the mice were nasally immunized three times (8w, 10w and 12w). Prevention of diabetes was associated with special humoral immune tolerance against tandem peptides GADIII. These data indicate that using CTB as a vaccine carrier, tandem GAD65 peptides can prevent T1D in NOD mice at the late stage of disease.

A double-edged sword in B-cell-targeted therapy for inflammatory diseases

Cells of the immune system, including B cells, perform inflammatory functions against microbial invasion, accompanied by anti-inflammatory responses to avoid host damage. B-cell-depletion therapy using anti-CD20 monoclonal antibodies against inflammatory diseases has beneficial or adverse effects depending on the timing and/or microenvironment in which they are used. To achieve effective B-cell-targeted therapy, it is necessary to identify and understand the modes of action of pathogenic and regulatory B cells, which include antibody production, formation of immune complexes, cytokine and chemokine production, cytotoxic killing, lymphoid neogenesis and antigen presentation. B cells interact with multiple cells, including dendritic cells, T cells and natural killer T cells, creating a complex regulatory network. Specific targeting of B-cell subsets and/or their interaction partners might lead to clinical benefits with minimal host damage.

The clinical spectrum and immunobiology of parainfectious neuromyelitis optica (Devic) syndromes

In a subgroup of patients with neuromyelitis optica (NMO), a severe inflammatory demyelinating disorder of autoimmune origin characterized by recurrent attacks of optic neuritis and longitudinally extensive transverse myelitis, a parainfectious pathogenesis may play a central role. We systematically evaluated such reports in the literature published between 1975 and 2009 in order to characterize parainfectious NMO syndromes. Identified were 25 cases, whereof 11 were in association with viral and 14 with bacterial pathogens. Sufficient clinical and paraclinical information was available in 16 patients (11 women). Median age was 8 years for children and 32 years for adults. Acute febrile illness preceding or in close relation with neurological symptoms was most common and the association with varicella-zoster virus and Mycobacterium pneumonia most frequent. In the majority, the course was monophasic (88%) and disability sustained (with complete recovery in only 25%). Seven patients fulfilled the revised NMO diagnosis criteria of 2006; none was seropositve for aquaporin-4 antibodies. Immune mechanisms potentially involved in parainfectious NMO syndromes include bystander activation, molecular mimicry, and the exacerbation of a pre-existing central nervous system (CNS) disorder by a systemic infection. However, current studies are not sufficient to define the place of parainfectious NMO syndromes within the spectrum of inflammatory disorders of the CNS.

Comparison of three anti-CCP antibody tests and rheumatoid factor in RA and control patients

It was the aim of this study to compare the diagnostic properties of two second generation anti-CCP antibodies assays (Quanta Lite CCP, Inova and EliA CCP, Phadia) with an assay containing a new antigen mixture (Quanta Lite CCP 3, Inova) and RF IgM.

METHODS

Sera from 86 RA patients and 90 control patients with other diseases, such as infections, connective tissue diseases, or other rheumatic diseases, were analysed using the four different methods. Specificity (84.4%) and PPV (80.3%) were lowest for RF IgM and highest for EliA CCP (specificity 97.8%, PPV 96.7%), the other values being close to those of EliA CCP. Sensitivity was highest for Quanta Lite CCP (73.3%). Efficiency was highest for Quanta Lite CCP (84.1%) at the lower cut off followed by EliA CCP at both cut offs (83.0%). The discrimination between RA sera (mean value 407.67 U/ml) and control sera (4.54 U/ml) and the relative risk (23.34) were best for EliA CCP. The results of this study reveal that there was no advantage of the anti-CCP antibodies assay applying a new antigen mixture (Quanta Lite CCP 3 ELISA) compared to two second generation anti-CCP antibodies assays (Quanta Lite CCP ELISA and EliA CCP).

Development of a Murine model to dissect the CpG-oligonucleotide-enhancement of the killing of human B Cells by rituximab

As a model to dissect the effects of CpG-oligonucleotides (CpG) on rituximab (RTX)-mediated therapeutic killing of autoimmune or malignant B lymphocytes, nude mice were grafted with Daudi human B cells. These mice were then injected with RTX alone or together with CpG. The human B cell aggregate was measured, and the reactive infiltrate analyzed after selective depletion of murine circulating cells. Macrophages (MØ) were identified in infiltrates, but not polymorphonuclear neutrophils (PMN), as confirmed by the failure of quantitative polymerase chain reaction to detect transcripts for PMN-specific myeloperoxidase in graft extracts. Evidence that MØ predominate over PMN in the anti-B cell RTX-induced immune mechanisms, include the presence of MØ-derived cytokines, and the lack of consequences of depletion of NK cells or B lymphocytes on the CpG-mediated effects on RTX. Interestingly however, removal of circulating PMN reduced the number of MØ attracted by the Daudi B cells. Our interpretation that CpG-induced complement activation is required for PMN to influence MØ was first based on overproduction of C5a in treated mice. This excess was due to the binding of the inhibitor of the alternative pathway of complement to CpG, as demonstrated by the elution of factor H from CpG-affinity-chromatography columns. Thus MØ are recruited to the tissue in the presence of C5a, and exploited locally by RTX.

Autoantibody IgG subclasses to recombinant antigens and the role of bacterial stimuli in primary biliary cirrhosis

AIM

Serum antimitochondrial antibody (AMA) of the IgG2 and IgG3 subclasses has been reported to be predominant in patients with primary biliary cirrhosis from developed countries. No data are available as to the significance of AMA subtypes in Japanese primary biliary cirrhosis (PBC) patients who have previously manifested unique serological features, nor it is known whether AMA subclasses are influenced by bacterial stimuli, as suggested by the molecular theory of PBC. We undertook a three-step study to address these questions.

METHODS

First, Japanese PBC sera were tested using the established triple recombinant antigen (pML-MIT3) to find AMA subclass distribution. Second, we used the three recombinant mitochondrial antigens in PBC sera of Japanese and USA patients to explore the ethnic difference. Third, we used CpG oligodeoxynucleotides and a B cell mitogen to challenge ex vivo peripheral leukocytes from indirect immunofluorescence (IIF)-AMA-positive patients with Japanese PBC.

RESULTS

We detected most frequently IgG2-AMA followed by IgG3-AMA, with the latter being more common in IIF-AMA-positive cases, and demonstrated that the IgG3 reactivity against the dominant antigen was significantly higher in PBC sera from the USA. We determined that the bacterial stimulus was superior to the mitogen at inducing a predominant production of IgG2-AMA and CD20+ B cell activation.

CONCLUSION

Our data cumulatively supported the hypothesis that IgG2 AMA subtypes are predominant in PBC and suggest that this might be favored by an innate immune reaction against bacterial particles, such as CpG DNA.

The role of environmental factors in primary biliary cirrhosis

The etiology of primary biliary cirrhosis (PBC) is enigmatic, although it is clearly related to a combination of genetic predisposition and environmental stimulation. PBC is a chronic autoimmune cholestatic liver disease that occurs throughout the world with a reported latitudinal gradient in prevalence and incidence. PBC is also characterized by a 60% concordance in monozygotic twins and is considered a model autoimmune disease because of several features common to other conditions and the relatively homogeneous serological and biochemical features. Several risk factors have been suggested to be associated with PBC, including exposure to infectious agents and chemical xenobiotics. This review will attempt to place such factors in perspective.

The weight of interleukin-6 in B cell-related autoimmune disorders

Interleukin (IL)-6 is a prevailing factor of polyclonal B-cell activation of B cells, and thereby of their tolerance breach. Its receptor (R) complex consists of a transducing unit, and a membrane-bound or soluble protein. Many activities ascribed to this cytokine are generated by the soluble IL-6R. Evidence has however been gleaned in autoimmune diseases that the system is instrumental in rheumatoid arthritis (RA), Sjögren's syndrome and systemic lupus erythematosus (SLE). To gain insight into the understanding of the mechanisms behind these observations, a prime example is the recombination-activating gene (Rag) machinery in B lymphocytes. It is interesting that the expression of Rags is favored by IL-6, and repressed by anti-IL-6R antibody (Ab) in RA and SLE. Not surprisingly, clinical benefits are reported in the treatment of autoimmune disorders with anti-IL-6R Ab, and other perspectives about to be open in biotherapy.

B cells contribute to ischemia/reperfusion-mediated tissue injury

Multiple elements are known to participate in ischemia/reperfusion (I/R)-mediated tissue injury. Amongst them, B cells have been shown to contribute by the production of antibodies that bind to ischemic cells and fix complement. It is currently unknown whether B cells participate through antibody-independent mechanisms in the pathogenesis of I/R. In a mesenteric I/R model we found that B cells infiltrate the injured intestine of normal and autoimmune mice 2h after reperfusion is established. B cell depletion protected mice from the development of I/R-mediated intestinal damage. The protection conferred by B cell depletion was significantly greater in MRL/lpr mice. Finally, we show that ischemic tissue expressed the B cell-attractant CXCL13 and infiltrating B cells expressed the corresponding receptor CXCR5. Our data grant B cells an antibody-independent role in the pathogenesis of intestinal I/R and suggest that B cells accumulate in the injured tissue in response to the chemokine CXCL13.

Long term treatment of rheumatoid arthritis with rituximab

B cells play an important role in the pathogenesis of rheumatoid arthritis (RA). Rituximab is a chimeric monoclonal antibody that depletes B-cells by binding to the CD20 surface antigen that has been approved for the treatment of RA. Its efficacy has been clearly demonstrated by different clinical trials and, recently, in long-term observational studies. The use of rituximab in clinical practice has highlighted its efficacy and safety over more than 5 years of treatment, as well as to try to understand the timing for retreatment of patients relapsing after a good initial response.

Preliminary study on the immunologic background of good clinical outcome in rheumatoid arthritis patients after one month therapy with leflunomide

This preliminary study focuses on early peripheral cellular immune changes after 1 month therapy with leflunomide, in 18 patients with severe rheumatoid arthritis, previously treated with methotrexate. A good clinical outcome of disease was documented and we showed that a particular target of short-time leflunomide therapy in rheumatoid arthritis was the peripheral innate immune system (NK cells and the population of granulocytes developing phagocytosis and superoxide anion production when challenged ex vivo with zymosan particles). Meanwhile, the high inter-individual variability of adaptive immunity required data analysis in subgroups of patients. We showed that the abnormal increase of peripheral leukocytes counts, or the decrease towards normal values of the CD4:CD8 lymphocytes ratio, or the inhibition of uridine uptake by ex vivo activated lymphocytes were consistent with a positive clinical evolution, proved by the reduction of tender/swollen joints, morning stiffness duration or acute phase response. We emphasized that significant benefits of short-term leflunomide therapy were associated with functional suppression of peripheral B lymphocytes. Hence, the positive evolution of rheumatoid arthritis patients seemed to be specifically linked to early drug-induced changes of trafficking or uridine metabolism of mononuclear cells.

The role of DC-STAMP in maintenance of immune tolerance through regulation of dendritic cell function

Regulation of dendritic cell (DC) function is critical for maintaining self-tolerance and preventing autoimmunity. The dendritic cell-specific transmembrane protein (DC-STAMP) plays a key role in cell-cell fusion of osteoclasts and foreign body giant cells, but though originally identified in DCs, its specific roles there remain undefined. Here, we report that aged DC-STAMP-deficient mice display several systemic autoimmune symptoms such as spontaneous lymphoproliferation, splenomegaly associated with infiltration of T cells in several organs and increased serum anti-double-stranded DNA antibody production. Although a lack of DC-STAMP did not inhibit DC differentiation or proliferation, antigen presentation activity of DC-STAMP-deficient DCs was significantly up-regulated in both class I and II pathways through increased phagocytotic activity compared with wild-type DCs, an activity likely leading to autoimmunity. Our results indicate that DC-STAMP is required for proper regulation of DC activity and maintenance of immune self-tolerance.

Etiopathogenesis of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune disease of the liver characterized by progressive bile duct destruction eventually leading to cirrhosis and liver failure. The serological hallmark of the disease is the presence of circulating antimitochondrial antibodies (AMA). These reflect the presence of autoreactive T and B cells to the culprit antigens, the E2 subunits of mitochondrial 2-oxo-acid dehydrogenase enzymes, chiefly pyruvate dehydrogenase (PDC-E2). The disease results from a combination of genetic and environmental risk factors. Genetic predisposition is indicated by the higher familial incidence of the disease particularly among siblings and the high concordance rate among monozygotic twins. Environmental triggering events appear crucial to disrupt a pre-existing unstable immune tolerance of genetic origin allowing, after a long latency, the emergence of clinical disease. Initiating mimotopes of the vulnerable epitope of the PDC-E2 autoantigen can be derived from microbes that utilize the PDC enzyme or, alternatively, environmental xenobiotics/chemical compounds that modify the structure of native proteins to make them immunogenic. A further alternative as a source of antigen is PDC-E2 derived from apoptotic cells. In the effector phase the biliary ductular cell, by reason of its proclivity to express the antigen PDC-E2 in the course of apoptosis, undergoes a multilineage immune attack comprised of CD4⁺ and CD8⁺ T cells and antibody. In this article, we critically review the available evidence on etiopathogenesis of PBC and present interpretations of complex data, new developments and theories, and nominate directions for future research.

New functions for an iron storage protein: the role of ferritin in immunity and autoimmunity

Ferritin is a ubiquitous and specialised protein involved in the intracellular storage of iron; it is also present in serum and other biological fluids, although its secretion processes are still unclear. We here review evidence supporting the hypothesis that macrophages play a role in the production and secretion of extracellular ferritin, as well as evidence supporting a novel function as a signalling molecule and immune regulator. In particular, H-ferritin, which inhibits the proliferation of lymphoid and myeloid cells, may be regarded as a negative regulator of human and murine hematopoiesis. The idea that it also acts as a signalling protein has been supported by the cloning and characterisation of the specific H-ferritin receptor TIM-2, a member of the TIM gene family. A number of studies of the mouse TIM gene family indicate that this protein plays an important role in immune-mediated diseases. This last finding, together with the fact that ferritin acts as an immuno-suppressor, has allowed us to formulate hypotheses regarding the possible role of alterations of H-ferritin/TIM-2 binding/signalling in the pathogenesis of autoimmune diseases.

Disturbances in B- and T-cell homeostasis in rheumatoid arthritis: suggested relationships with antigen-driven immune responses

Naïve and memory B- and T-cell subsets were examined with three-color flow cytometry in the peripheral blood of patients with rheumatoid arthritis (RA) in comparison with healthy controls, and their association with disease duration, activity and autoantibodies was investigated in order to reveal potential imprints of antigen-specific immune response in RA. The B-cell population consisted of significantly less naïve (58.1+/-3.9% versus 68.7+/-3.7%; p=0.04), and more IgD-/CD27+ memory B cells (19.6+/-2.1% versus 13.7+/-2.1%; p=0.04) compared to healthy subjects. In addition, strong correlation was demonstrated between disease duration and the percentage of memory B cells (p<0.0001). Increased CD8+ terminally differentiated effector memory/central memory T-cell ratio (1.35+/-0.35 versus 0.84+/-0.24) was also detected in RA patients compared with controls, which also correlated with the duration of RA (p=0.005). The frequency of memory B cells and CD8+ effector memory T cells correlated with the proportion of CD4+ effector memory lymphocytes, suggesting cooperation between immune cells. Our results reflect disturbances in B- and T-cell homeostasis characterized by the accumulation of memory B cells and a shift towards CD8+ terminally differentiated effector memory T cells in RA, suggesting ongoing, antigen-driven immune response and accelerated differentiation of B and T lymphocytes into effector cells.

Naturally occurring B-cell autoreactivity: A critical overview

In over one century of research in immunology marked progress in the scientific knowledge and the implications derived from it has been made. At the same time several contradictory and seemingly opposing results have been obtained. The term autoimmunity is still conceived by many as a term directly related to an immunopathological state. However, strong evidence exist that not only the immune system is able to recognize self-constituents, but it appears also that this property is essential for homeostasis. Direct or indirect alterations of such self-recognition properties of the immune system may contribute to pathology. In this review, the most recent advances in the field of naturally occurring B-cell autoreactivity in health as well as in disease are presented and discussed.

Autoimmunity and pathophysiology

Several matters concerning the term "Autoimmunity" have arisen the last two decades. Most researchers agree that a degree of natural autoimmunity in the absence of disease is needed for the development of effective immune responses against infectious agents or cancer cells. Individuals, however, with suitable genetic background and after exposure to certain environmental triggers (such as UV radiation, bacteria, viruses, etc) may develop an exaggerated immune response against self leading to the development of several autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus etc. In this context, a the meeting on "Autoimmunity: Physiological and Pathophysiological Aspects" was held on May in Athens, Greece aiming to bring together and discuss different points of view of the principal investigators that have contributed in the development of this field during the last years. Several aspects of both natural and pathological autoimmunity as well as the possible links between these two states are presented by leading authorities of the field in this special issue.