Sequential polymicrobial infections lead to CNS inflammatory disease: possible involvement of bystander activation in heterologous immunity

Critical evaluation on roles of macrophagic myofasciitis and aluminum adjuvants in HPV vaccine-induced adverse events

Cervical cancer is caused by human papillomavirus (HPV) infection, which is preventable by HPV vaccines. In Japan, the HPV vaccination rate has remained extremely low due to the concerns for alleged neuropsychological symptoms or "diverse symptoms" following injections of two HPV vaccines, Cervarix and Gardasil, in HPV vaccine lawsuits. In the lawsuits, the attorneys' group has used several manuscripts proposing that aluminum (Al) adjuvant contained in HPV vaccines causes an immune-mediated disease, called macrophagic myofasciitis (MMF), as well as pathology in the central nervous system (CNS). We scientifically evaluated these manuscripts describing the "Al adjuvant-induced pathologies," particularly MMF. Although MMF patients have been reported to develop clinical symptoms/signs in various organs, including the CNS, muscle biopsy of the patients and animal experiments demonstrated that MMF pathology was localized only at the injected muscle. No muscle pathology which characterizes MMF was observed in any other muscles; thus, the systemic and neurological signs of MMF cases were irrelevant to localized MMF pathology. We evaluated that MMF-like pathology was induced as a local inflammatory response following vaccinations; MMF pathology was not the cause of systemic inflammation or "diverse symptoms." Lastly, MMF cases have been reported after vaccinations with Al-hydroxide-containing vaccines exclusively. As Al-hydroxide is a component of Cervarix, but not Gardasil, "diverse symptoms" following two HPV vaccinations in Japan cannot be explained by MMF. Our evaluation would help readers understand the validity of the manuscripts on the role of Al adjuvants or MMF for the alleged "diverse symptoms."

Examining pathogenic concepts of autoimmune hepatitis for cues to future investigations and interventions

BACKGROUND

Multiple pathogenic mechanisms have been implicated in autoimmune hepatitis, but they have not fully explained susceptibility, triggering events, and maintenance or escalation of the disease. Furthermore, they have not identified a critical defect that can be targeted. The goals of this review are to examine the diverse pathogenic mechanisms that have been considered in autoimmune hepatitis, indicate investigational opportunities to validate their contribution, and suggest interventions that might evolve to modify their impact. English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed. Genetic and epigenetic factors can affect susceptibility by influencing the expression of immune regulatory genes. Thymic dysfunction, possibly related to deficient production of programmed cell death protein-1, can allow autoreactive T cells to escape deletion, and alterations in the intestinal microbiome may help overcome immune tolerance and affect gender bias. Environmental factors may trigger the disease or induce epigenetic changes in gene function. Molecular mimicry, epitope spread, bystander activation, neo-antigen production, lymphocytic polyspecificity, and disturbances in immune inhibitory mechanisms may maintain or escalate the disease. Interventions that modify epigenetic effects on gene expression, alter intestinal dysbiosis, eliminate deleterious environmental factors, and target critical pathogenic mechanisms are therapeutic possibilities that might reduce risk, individualize management, and improve outcome. In conclusion, diverse pathogenic mechanisms have been implicated in autoimmune hepatitis, and they may identify a critical factor or sequence that can be validated and used to direct future management and preventive strategies.

Bystander T Cells: A Balancing Act of Friends and Foes

T cell responses are essential for appropriate protection against pathogens. T cell immunity is achieved through the ability to discriminate between foreign and self-molecules, and this relies heavily on stringent T cell receptor (TCR) specificity. Recently, bystander activated T lymphocytes, that are specific for unrelated epitopes during an antigen-specific response, have been implicated in diverse diseases. Numerous infection models have challenged the classic dogma of T cell activation as being solely dependent on TCR and major histocompatibility complex (MHC) interactions, indicating an unappreciated role for pathogen-associated receptors on T cells. We discuss here the specific roles of bystander activated T cells in pathogenesis, shedding light on the ability of these cells to modulate disease severity independently from TCR recognition.

Making Mouse Models That Reflect Human Immune Responses

Humans are infected with a variety of acute and chronic pathogens over the course of their lives, and pathogen-driven selection has shaped the immune system of humans. The same is likely true for mice. However, laboratory mice we use for most biomedical studies are bred in ultra-hygienic environments, and are kept free of specific pathogens. We review recent studies that indicate that pathogen infections are important for the basal level of activation and the function of the immune system. Consideration of these environmental exposures of both humans and mice can potentially improve mouse models of human disease.

Th17-biased RORγt transgenic mice become susceptible to a viral model for multiple sclerosis

In a viral model for multiple sclerosis (MS), Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), both immune-mediated tissue damage (immunopathology) and virus persistence have been shown to cause pathology. T helper (Th) 17 cells are a Th cell subset, whose differentiation requires the transcription factor retinoic acid-related orphan receptor (ROR) γt, secrete pro-inflammatory cytokines, including IL-17, and can antagonize Th1 cells. Although Th17 cells have been shown to play a pathogenic role in immune-mediated diseases or a protective role in bacterial and fungal infections, their role in viral infections is unclear. Using newly established Th17-biased RORγt Tg mice, we tested whether Th17 cells could play a pathogenic or protective role in TMEV-IDD by contributing to immunopathology and/or by modulating anti-viral Th1 immune responses. While TMEV-infected wild-type littermate C57BL/6 mice are resistant to TMEV-IDD, RORγt Tg mice developed inflammatory demyelinating lesions with virus persistence in the spinal cord. TMEV-infected RORγt Tg mice had higher levels of IL-17, lower levels of interferon-γ, and fewer CD8(+) T cells, without alteration in overall levels of anti-viral lymphoproliferative and antibody responses, compared with TMEV-infected wild-type mice. This suggests that a Th17-biased "gain-of-function" mutation could increase susceptibility to virus-mediated demyelinating diseases.

Unresolved issues in theories of autoimmune disease using myocarditis as a framework

Many theories of autoimmune disease have been proposed since the discovery that the immune system can attack the body. These theories include the hidden or cryptic antigen theory, modified antigen theory, T cell bypass, T cell-B cell mismatch, epitope spread or drift, the bystander effect, molecular mimicry, anti-idiotype theory, antigenic complementarity, and dual-affinity T cell receptors. We critically review these theories and relevant mathematical models as they apply to autoimmune myocarditis. All theories share the common assumption that autoimmune diseases are triggered by environmental factors such as infections or chemical exposure. Most, but not all, theories and mathematical models are unifactorial assuming single-agent causation of disease. Experimental and clinical evidence and mathematical models exist to support some aspects of most theories, but evidence/models that support one theory almost invariably supports other theories as well. More importantly, every theory (and every model) lacks the ability to account for some key autoimmune disease phenomena such as the fundamental roles of innate immunity, sex differences in disease susceptibility, the necessity for adjuvants in experimental animal models, and the often paradoxical effect of exposure timing and dose on disease induction. We argue that a more comprehensive and integrated theory of autoimmunity associated with new mathematical models is needed and suggest specific experimental and clinical tests for each major theory that might help to clarify how they relate to clinical disease and reveal how theories are related.

Antibodies as predictors of autoimmune diseases and cancer

BACKGROUND

Autoantibodies targeted against a variety of self-antigens are detected in autoimmune diseases and cancer. Emerging evidence has suggested the involvement of environmental factors such as infections and xenobiotics, and some dietary proteins and their antibodies in the pathogenesis of many autoimmune diseases. These antibodies appear in the blood years before presentation of symptoms in various disorders. Therefore, these antibodies may be used as biomarkers for early detection of various diseases.

OBJECTIVE

To provide an overview of antibody arrays that are measured against different human tissue antigens, crossreactive epitopes of infectious agents, dietary proteins, and haptenic chemicals in autoimmune diseases and cancer.

METHOD

Microarray analysis of antigen-antibody reaction.

CONCLUSION

The application of these antibody arrays to human autoimmune disease is expanding and is allowing for the identification of patterns or antibody signatures, thus establishing the premises for increased sensitivity and specificity of prediction, as well as positive predictive values. The presence of these antibodies would not necessarily mean that a patient would definitely become sick but may give a percentage of risk for different conditions that may develop over future months or years. Using this high-throughput microarray method, it is possible to screen rapidly for dozens of autoantibodies at low cost. This is an important factor in the implementation of autoantibody testing as a routine part of medical examinations.

Possible role of interleukin-17 in a prime/challenge model of multiple sclerosis

No one single pathogen has been identified as the causative agent of multiple sclerosis (MS). Alternately, the likelihood of an autoimmune event may be nonspecifically enhanced by different infectious agents. In a novel animal model of MS, SJL/J mice primed through infection with a recombinant vaccinia virus (VV) encoding myelin proteolipid protein (PLP) (VV(PLP)) were susceptible to a central nervous system (CNS) inflammatory disease following administration of a nonspecific immunostimulant [complete Freund's adjuvant (CFA) plus Bordetella pertussis (BP)]. Mononuclear cells isolated from the brains, but not the spleens, of VV(PLP)-primed CFA/BP challenged mice produced interleukin (IL)-17 and interferon-γ and transferred a CNS inflammatory disease to naïve SJL/J mice. Administration of curdlan, a T helper 17 cell inducer, unexpectedly resulted in less severe clinical and histological signs of disease, compared to CFA/BP challenged mice, despite the induction of IL-17 in the periphery. Further examination of the VV(PLP)-prime CFA/BP challenge model may suggest new mechanisms for how different pathogens associated with MS can protect or enhance disease.

Molecular mimicry as a mechanism of autoimmune disease

A variety of mechanisms have been suggested as the means by which infections can initiate and/or exacerbate autoimmune diseases. One mechanism is molecular mimicry, where a foreign antigen shares sequence or structural similarities with self-antigens. Molecular mimicry has typically been characterized on an antibody or T cell level. However, structural relatedness between pathogen and self does not account for T cell activation in a number of autoimmune diseases. A proposed mechanism that could have been misinterpreted for molecular mimicry is the expression of dual T cell receptors (TCR) on a single T cell. These T cells have dual reactivity to both foreign and self-antigens leaving the host vulnerable to foreign insults capable of triggering an autoimmune response. In this review, we briefly discuss what is known about molecular mimicry followed by a discussion of the current understanding of dual TCRs. Finally, we discuss three mechanisms, including molecular mimicry, dual TCRs, and chimeric TCRs, by which dual reactivity of the T cell may play a role in autoimmune diseases.

CMV infection attenuates the disease course in a murine model of multiple sclerosis

Recent evidence in multiple sclerosis (MS) suggests that active CMV infection may result in more benign clinical disease. The goal of this pilot study was to determine whether underlying murine CMV (MCMV) infection affects the course of the Theiler's murine encephalitis virus (TMEV) induced murine model of MS. A group of eight TMEV-infected mice were co-infected with MCMV at 2 weeks prior to TMEV infection while a second group of TMEV-infected mice received MCMV two weeks post TMEV. We also used 2 control groups, where at the above time points MCMV was replaced with PBS. Outcome measures included (1) monthly monitoring of disability via rotarod for 8 months; (2) in vivo MRI for brain atrophy studies and (3) FACS analysis of brain infiltrating lymphocytes at 8 months post TMEV infection. Co-infection with MCMV influenced the disease course in mice infected prior to TMEV infection. In this group, rotarod detectable motor performance was significantly improved starting 3 months post-infection and beyond (p≤0.024). In addition, their brain atrophy was close to 30% reduced at 8 months, but this was only present as a trend due to low power (p = 0.19). A significant reduction in the proportion of brain infiltrating CD3+ cells was detected in this group (p = 0.026), while the proportion of CD45+ Mac1+ cells significantly increased (p = 0.003). There was also a strong trend for a reduced proportion of CD4+ cells (p = 0.17) while CD8 and B220+ cell proportion did not change. These findings support an immunomodulatory effect of MCMV infection in this MS model. Future studies in this co-infection model will provide insight into mechanisms which modulate the development of demyelination and may be utilized for the development of novel therapeutic strategies.

Experimental autoimmune encephalomyelitis as a testing paradigm for adjuvants and vaccines

Experimental autoimmune encephalomyelitis (EAE) is an experimental model for multiple sclerosis. EAE can be induced by inoculation with central nervous system (CNS) proteins or peptides emulsified in complete Freund's adjuvant. Protection from EAE, enhancement of EAE or subclinical priming for EAE can occur as a result of either live viral infection or DNA immunization with molecular mimics of CNS proteins or peptides. Here we review the published data describing modulation of EAE through administration of various CNS proteins/peptides introduced via live virus or plasmid DNA and modulation of EAE through choice of adjuvant (immunostimulating agents).

Studies in the modulation of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE), an experimental model for multiple sclerosis, can be induced through inoculation with several different central nervous system (CNS) proteins or peptides. Modulation of EAE, resulting in either protection from EAE or enhancement of EAE, can also be accomplished through either vaccination or DNA immunization with molecular mimics of self-CNS proteins. Previously published data on this method of EAE modulation will be reviewed. New data is presented, which demonstrates that EAE can also be modulated through the administration of the beta-(1,3)-D-glucan, curdlan. Dendritic cells stimulated by curdlan are involved in the differentiation of the interleukin-17 producing subset of CD4(+) T cells that are recognized effector cells in EAE. Using two different systems to study the effects of curdlan on EAE, it was found that curdlan increased the incidence of EAE and/or the severity of the disease course.

Potential triggers of MS

MS is an immune mediated disease of the central nervous system (CNS) characterized by demyelination, axonal damage and neurologic disability. The primary cause of this CNS disease remains elusive. Here we will address our current understanding of the role of viruses as potential environmental triggers for MS. Virus infections can act peripherally (outside the CNS) or within the CNS. The association of viral infections with demyelinating disease, in both animals and humans, will be discussed, as will the potential contributions of peripheral infection with Torque Teno virus, infection outside of and/or within the CNS with Epstein-Barr virus and infection within the CNS with Human Herpesvirus 6 to MS. An experimental animal model, Theiler's murine encephalomyelitis virus infection of susceptible strains of mice is an example of viral infections of the CNS as a prerequisite for demyelination. Finally, the proposition that multiple virus infections are required, which first prime the immune system and then trigger the disease, as a model where infections outside of the CNS lead to inflammatory changes within the CNS, for the development of a MS-like disease is explored.

Antigenic complementarity between coxsackie virus and streptococcus in the induction of rheumatic heart disease and autoimmune myocarditis

A variety of clinical, epidemiological, and experimental data suggest that rheumatic heart disease and autoimmune myocarditis are not only similar in their pathogenesis, but may often be due to combined infections with coxsackie virus (CX) and streptococcus A bacteria (SA). This paper reviews the evidence for this hypothesis, provides some new experimental data supporting the hypothesis, and suggests specific experiments for testing it. While, it is well-established that the M protein of SA mimics myosin, we demonstrate using homology search tools that various CX proteins mimic actin. We further demonstrate that antibody against CX recognizes actin as an antigen, and that anti-actin antibodies recognize CX antigen. Thus, anti-CX antibodies may also target muscle. Moreover, since myosin and actin are molecularly complementary, it follows that some SA and CX proteins may be molecularly complementary. Some antibodies against these complementary proteins in SA and CX should therefore act like idiotype-antiidiotype antibodies. We show that, indeed, CX and SA antibodies precipitate each other. Thus, it is possible that combined CX-SA infections produce more severe disease by producing pairs of idiotypic antibodies that act like antiidiotypic antibodies as well, thereby, disregulating immune control and triggering an autoimmune reaction against both myosin and actin simultaneously. We predict that combinations of the appropriate actin- and myosin-like antigens from CX and SA will, therefore, be much more autoimmunogenic than antigens from CX or SA alone, and that the combination will not require use of adjuvants or self-proteins that many current protocols require. It is possible that co-infections involving CX or SA with other infectious agents may produce similarly enhanced disease.

Antibodies as predictors of complex autoimmune diseases and cancer

The pathologic role of autoantibodies in many autoimmune diseases is widely accepted. An enzyme immunoassay was used for measurement of antibodies against disease-specific antigens and etiologic agents for cross-reactive antigens associated with them. This antibody assay was applied to a panel of antigens for the detection of different neuroautoimmune diseases that included multiple sclerosis, motor peripheral neuropathies, multifocal motor neuropathy, amyotrophic lateral sclerosis, pediatric autoimmune neuropsychiatric disorder associated with streptococcal infection. We studied women with pregnancies complicated by neural tube defect, neuroborreliosis, autism and patients with possible somatic hypermutation. Antibodies were also measured against antigens and etiologic agents associated with primary biliary cirrhosis and chronic obstructive pulmonary disease. And, finally, antibodies were measured against several tumor antigens or peptides which are expressed in prostatic, breast and colon tissues. This panel of different autoantibodies was applied to 290 patients with neuroautoimmune disorders, cancer, and possible somatic hypermutation. The levels of these antibodies against different tissue-specific antigens and etiologic agents associated with them were significantly elevated in patients versus controls. We hope that this novel 96 antigen-specific ELISA will be used in additional studies that will prove its clinical efficacy, not only for the early diagnosis of many neuroautoimmune, liver and lung autoimmune disorders, but also for prognosis and the implementation of preventive steps for many complex diseases.

Axonal degeneration as a self-destructive defense mechanism against neurotropic virus infection

Theiler's murine encephalomyelitis virus (TMEV) and other neurotropic virus infections result in degeneration of each component of the neuron: apoptosis of the cell body, axonal (Wallerian) degeneration, and dendritic and synaptic pathology. In general, axonal degeneration is detrimental for hosts. However, axonal degeneration can be beneficial in the case of infection with neurotropic viruses that spread in the CNS using axonal transport. C57BL/Wld(S) (Wld(S), Wallerian degeneration slow mutant) mice are protected from axonal degeneration. Wld(S) mice infected with the neurovirulent GDVII strain of TMEV are more resistant to virus infection than wild-type mice, suggesting that axonal preservation contributes to the resistance. By contrast, infection with the less virulent Daniels strain of TMEV results in high levels of virus propagation in the CNS, suggesting that prolonged survival of axons in Wld(S) mice favors virus spread. Thus, axonal degeneration might be a beneficial self-destruct mechanism that limits the spread of neurotropic viruses, in the case of less virulent virus infection. We hypothesize that neurons use 'built-in' self-destruct protection machinery (compartmental neurodegeneration) against neurotropic virus infection, since the CNS is an immunologically privileged site. Early induction of apoptosis in the neuronal cell body limits virus replication. Wallerian degeneration of the axon prevents axonal transport of virus. Dendritic and synaptic degeneration blocks virus transmission at synapses. Thus, the balance between neurodegeneration and virus propagation may be taken into account in the future design of neuroprotective therapy.