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Abstract Background Insulin dependent (i.e., "type 1") diabetes mellitus (T1DM) is considered to be a T cell mediated disease in which TH1 and Tc autoreactive cells attack the pancreatic islets. Among the beta-cell antigens implicated in T1DM, glutamic acid decarboxylase (GAD) 65 appears to play a key role in the development of T1DM in humans as well as in non-obese diabetic (NOD) mice, the experimental model for this disease. It has been shown that shifting the immune response to this antigen from TH1 towards TH2, via the administration of GAD65 peptides to young NOD mice, can suppress the progression to overt T1DM. Accordingly, various protocols of "peptide immunotherapy" of T1DM are under investigation. However, in mice with experimental autoimmune encephalomyelitis (EAE), another autoimmune TH1 mediated disease that mimics human multiple sclerosis, anaphylactic shock can occur when the mice are challenged with certain myelin self peptides that initially were administered with adjuvant to induce the disease. Results Here we show that NOD mice, that spontaneously develop T1DM, can develop fatal anaphylactic reactions upon challenge with preparations of immunodominant GAD65 self peptides after immunization with these peptides to modify the development of T1DM. Conclusions These findings document severe anaphylaxis to self peptide preparations used in an attempt to devise immunotherapy for a spontaneous autoimmune disease. Taken together with the findings in EAE, these results suggest that peptide therapies designed to induce a TH1 to TH2 shift carry a risk for the development of anaphylactic reactivity to the therapeutic peptides.

Our objective was to analyze longitudinal cellular and humoral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in people with multiple sclerosis (pwMS) on B-cell depleting treatment (BCDT) compared to pwMS without immunotherapy. We further evaluated the impact of COVID-19 infection and vaccination timing. PwMS ( n = 439) on BCDT (ocrelizumab, rituximab, ofatumumab) or without immunotherapy were recruited for this prospective cohort study between June 2021 and June 2022. SARS-CoV-2 spike-specific antibodies and interferon-γ release of CD4 and CD8 T-cells upon stimulation with spike protein peptide pools were analyzed at different timepoints (after primary vaccination, 3 and 6 months after primary vaccination, after booster vaccination, 3 months after booster). Humoral response to SARS-CoV-2 was consistently lower whereas T-cell response was higher in patients with BCDT compared to controls. Cellular and humoral responses decreased over time after primary vaccination and increased again upon booster vaccination, with significantly higher antibody titers after booster than after primary vaccination in both untreated and B-cell-depleted pwMS. COVID-19 infection further led to a significant increase in SARS-CoV-2-specific responses. Despite attenuated B-cell responses, a third vaccination for patients with BCDT seems recommendable, since at least partial protection can be expected from the strong T-cell response. Moreover, our data show that an assessment of T-cell responses may be helpful in B-cell-depleted patients to evaluate the efficacy of SARS-CoV-2 vaccination.

Background and Objectives: Our objective was to investigate cellular and humoral immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in a cohort of people with multiple sclerosis (pwMS) on pulsed B-cell-depleting treatment (BCDT). In particular, we intended to evaluate a possible association between immune responses and the timing of vaccination under BCDT., Methods: We conducted a cross-sectional study among pwMS on pulsed BCDT or without disease-modifying treatment after completed SARS-CoV-2 vaccination. Samples were collected during routine clinical visits at the Multiple Sclerosis Center Dresden, Germany, between June 2021 and September 2021. Blood was analyzed for SARS-CoV-2 spike protein-specific antibodies and interferon-γ release of CD4 and CD8 T cells on stimulation with spike protein peptide pools. Lymphocyte subpopulations and total immunoglobulin levels in the blood were measured as part of clinical routine., Results: We included 160 pwMS in our analysis, comprising 133 pwMS on BCDT (n = 132 on ocrelizumab and n = 1 on rituximab) and 27 without disease-modifying treatment. Humoral and cellular anti-SARS-CoV-2 responses were reciprocally regulated by the time between the last BCDT cycle and vaccination. Although antibody responses increased with prolonged intervals between the last BCDT cycle and vaccination, CD4 and CD8 T-cell responses were higher in pwMS vaccinated at early time points after the last BCDT cycle compared with untreated pwMS. T-cellular vaccination responses correlated with total, CD3 CD4, and partly with CD3 CD8 lymphocyte counts. Humoral responses correlated with CD19 lymphocyte counts. Status post coronavirus disease 2019 infection led to significantly increased SARS-CoV-2-specific T-cell and antibody responses., Discussion: Delaying BCDT is currently discussed as a strategy to optimize humoral responses to SARS-CoV-2 vaccination. However, T cells represent an important line of defense against SARS-CoV-2 infection as well, especially in light of emerging variants of concern. We observed enhanced CD4 and CD8 T-cellular responses in pwMS receiving vaccination at early time points after their last BCDT cycle. These data may influence clinical decision making with respect to vaccination strategies in patients receiving BCDT., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

The autoimmune immunopathology occurring in multiple sclerosis (MS) is sustained by myelin-specific and -nonspecific CD8 + T cells. We have previously shown that, in MS, activated T cells undergoing apoptosis induce a CD8 + T cell response directed against antigens that are unveiled during the apoptotic process, namely caspase-cleaved structural proteins such as non-muscle myosin and vimentin. Here, we have explored in vivo the development and the function of the immune responses to cryptic apoptosis-associated epitopes (AEs) in a well-established mouse model of MS, experimental autoimmune encephalomyelitis (EAE), through a combination of immunization approaches, multiparametric flow cytometry, and functional assays. First, we confirmed that this model recapitulated the main findings observed in MS patients, namely that apoptotic T cells and effector/memory AE-specific CD8 + T cells accumulate in the central nervous system of mice with EAE, positively correlating with disease severity. Interestingly, we found that AE-specific CD8 + T cells were present also in the lymphoid organs of unprimed mice, proliferated under peptide stimulation in vitro, but failed to respond to peptide immunization in vivo, suggesting a physiological control of this response. However, when mice were immunized with AEs along with EAE induction, AE-specific CD8 + T cells with an effector/memory phenotype accumulated in the central nervous system, and the disease severity was exacerbated. In conclusion, we demonstrate that AE-specific autoimmunity may contribute to immunopathology in neuroinflammation., (© 2021. The Author(s).)

The extrusion of DNA traps contributes to a key mechanism in which innate immune cells clear pathogens or induce sterile inflammation. Here we provide evidence that CD4 + T cells, a critical regulator of adaptive immunity, release extracellular threads of DNA on activation. These DNA extrusions convey autocrine costimulatory signals to T lymphocytes and can be detected in lymph nodes isolated during the priming phase of experimental autoimmune encephalomyelitis (EAE), a CD4 + T cell-driven mouse model of multiple sclerosis. Pharmacologic inhibition of mitochondrial reactive oxygen species (mtROS) abolishes the extrusion of DNA by CD4 + T cells, reducing cytokine production in vitro and T cell priming against myelin in vivo. Moreover, mtROS blockade during established EAE markedly ameliorates disease severity, dampening autoimmune inflammation of the central nervous system. Taken together, these experimental results elucidate a mechanism of intrinsic immune costimulation mediated by DNA threads released by activated T helper cells, and identify a potential therapeutic target for such disorders as multiple sclerosis, neuromyelitis optica, and CD4 + T cell-mediated disorders., Competing Interests: The authors declare no conflict of interest.

Objective: To investigate the effects of targeting the high-affinity receptor for immunoglobulin E (FcεRI), that plays a central role in allergic responses and is constitutively expressed on mast cells and basophils, in clinical disease and autoimmune T-cell response in experimental MS., Methods: Experimental autoimmune encephalomyelitis (EAE) was induced in C57BL/6 mice by immunization with myelin oligodendrocyte glycoprotein 35-55. Anti-FcεRI α-chain antibody was administered intraperitoneally. CNS immunohistochemistry, flow cytometry analysis of immune cell populations, IgE and histamine serum concentration, immune cell proliferation, and cytokine measurement were performed. In BALB/c mice, EAE was induced by immunization with myelin proteolipid protein 185-206., Results: Treatment with anti-FcεRIα antibody resulted in exacerbation of EAE and increased CNS inflammation in C57BL/6 mice. Treated mice displayed long-lasting complete depletion of basophils in the blood stream and peripheral lymphoid organs and increased antigen-induced immune cell proliferation and production of interferon-γ, interleukin (IL)-17, IL-6, and granulocyte-macrophage colony-stimulating factor. In BALB/c mice, which are T-helper (Th) 2 prone and resistant to EAE, treatment with anti-FcεRIα antibody restored susceptibility to EAE., Conclusion: Our observations that anti-FcεRIα antibody increases Th1 and Th17 responses against myelin antigen and exacerbates EAE suggest that FcεRI, basophils, and possibly other FcεRI-bearing cells that might be affected by this antibody play important roles in influencing the severity of CNS autoimmunity.

The higher prevalence of multiple sclerosis (MS) in females, along with the modulation of disease activity observed during pregnancy and the post-partum period, has suggested a hormonal influence in MS. Even if prolactin (PRL) does not belong to the sex hormones family, its crucial role in female reproduction and lactation has prompted great efforts to understand if PRL could represent a gender factor in the pathogenesis of MS and experimental autoimmune encephalomyelitis (EAE), the animal model for this disease. Extensive literature has documented a remarkable immune-stimulating potential for this hormone, indicating PRL as a disease-promoting factor in MS and EAE. However, recent work has pointed out that PRL is endowed with important neuroprotective and remyelinating properties and has encouraged a reinterpretation of the involvement of this hormone in MS. In this review we summarize both the protective functions that PRL exerts in central nervous system tissue as well as the inflammatory activity of this hormone in the context of autoimmune responses against myelin. Last, we draw future lines of research that might help to better clarify the impact of PRL on MS pathology., Competing Interests: The authors declare no conflict of interest.

Omenn syndrome (OS) is caused by hypomorphic Rag mutations and characterized by a profound immunodeficiency associated with autoimmune-like manifestations. Both in humans and mice, OS is mediated by oligoclonal activated T and B cells. The role of microbial signals in disease pathogenesis is debated. Here, we show that Rag2(R229Q) knock-in mice developed an inflammatory bowel disease affecting both the small bowel and colon. Lymphocytes were sufficient for disease induction, as intestinal CD4 T cells with a Th1/Th17 phenotype reproduced the pathological picture when transplanted into immunocompromised hosts. Moreover, oral tolerance was impaired in Rag2(R229Q) mice, and transfer of wild-type (WT) regulatory T cells ameliorated bowel inflammation. Mucosal immunoglobulin A (IgA) deficiency in the gut resulted in enhanced absorption of microbial products and altered composition of commensal communities. The Rag2(R229Q) microbiota further contributed to the immunopathology because its transplant into WT recipients promoted Th1/Th17 immune response. Consistently, long-term dosing of broad-spectrum antibiotics (ABXs) in Rag2(R229Q) mice ameliorated intestinal and systemic autoimmunity by diminishing the frequency of mucosal and circulating gut-tropic CCR9(+) Th1 and Th17 T cells. Remarkably, serum hyper-IgE, a hallmark of the disease, was also normalized by ABX treatment. These results indicate that intestinal microbes may play a critical role in the distinctive immune dysregulation of OS., (© 2016 Rigoni et al.)

We developed a novel therapeutic strategy for Alzheimer's disease (AD) exploiting the properties of a natural variant of Amyloid-β (Aβ) carrying the A2V substitution, which protects heterozygous carriers from AD by its ability to interact with wild-type Aβ, hindering conformational changes and assembly thereof. As prototypic compound we designed a six-mer mutated peptide (Aβ1-6A2V), linked to the HIV-related TAT protein, which is widely used for brain delivery and cell membrane penetration of drugs. The resulting molecule [Aβ1-6A2VTAT(D)] revealed strong anti-amyloidogenic effects in vitro and protected human neuroblastoma cells from Aβ toxicity. Preclinical studies in AD mouse models showed that short-term treatment with Aβ1-6A2VTAT(D) inhibits Aβ aggregation and cerebral amyloid deposition, but a long treatment schedule unexpectedly increases amyloid burden, although preventing cognitive deterioration. Our data support the view that the AβA2V-based strategy can be successfully used for the development of treatments for AD, as suggested by the natural protection against the disease in human A2V heterozygous carriers. The undesirable outcome of the prolonged treatment with Aβ1-6A2VTAT(D) was likely due to the TAT intrinsic attitude to increase Aβ production, avidly bind amyloid and boost its seeding activity, warning against the use of the TAT carrier in the design of AD therapeutics.

Objective: To investigate the potential role of prokineticin 2 (PK2), a bioactive peptide involved in multiple biological functions including immune modulation, in CNS autoimmune demyelinating disease., Methods: We investigated the expression of PK2 in mice with experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS), and in patients with relapsing-remitting MS. We evaluated the biological effects of PK2 on expression of EAE and on development of T-cell response against myelin by blocking PK2 in vivo with PK2 receptor antagonists. We treated with PK2 immune cells activated against myelin antigen to explore the immune-modulating effects of this peptide in vitro., Results: Pk2 messenger RNA was upregulated in spinal cord and lymph node cells (LNCs) of mice with EAE. PK2 protein was expressed in EAE inflammatory infiltrates and was increased in sera during EAE. In patients with relapsing-remitting MS, transcripts for PK2 were significantly increased in peripheral blood mononuclear cells compared with healthy controls, and PK2 serum concentrations were significantly higher. A PK2 receptor antagonist prevented or attenuated established EAE in chronic and relapsing-remitting models, reduced CNS inflammation and demyelination, and decreased the production of interferon (IFN)-γ and interleukin (IL)-17A cytokines in LNCs while increasing IL-10. PK2 in vitro increased IFN-γ and IL-17A and reduced IL-10 in splenocytes activated against myelin antigen., Conclusion: These data suggest that PK2 is a critical immune regulator in CNS autoimmune demyelination and may represent a new target for therapy.

Wiskott-Aldrich Syndrome protein (WASP) is a key regulator of the actin cytoskeleton in hematopoietic cells. Defective expression of WASP leads to multiple abnormalities in different hematopoietic cells. Despite severe impairment of T cell function, WAS patients exhibit a high prevalence of autoimmune disorders. We attempted to induce EAE, an animal model of organ-specific autoimmunity affecting the CNS that mimics human MS, in Was(-/-) mice. We describe here that Was(-/-) mice are markedly resistant against EAE, showing lower incidence and milder score, reduced CNS inflammation and demyelination as compared to WT mice. Microglia was only poorly activated in Was(-/-) mice. Antigen-induced T-cell proliferation, Th-1 and -17 cytokine production and integrin-dependent adhesion were increased in Was(-/-) mice. However, adoptive transfer of MOG-activated T cells from Was(-/-) mice in WT mice failed to induce EAE. Was(-/-) mice were resistant against EAE also when induced by adoptive transfer of MOG-activated T cells from WT mice. Was(+/-) heterozygous mice developed an intermediate clinical phenotype between WT and Was(-/-) mice, and they displayed a mixed population of WASP-positive and -negative T cells in the periphery but not in their CNS parenchyma, where the large majority of inflammatory cells expressed WASP. In conclusion, in absence of WASP, T-cell responses against a CNS autoantigen are increased, but the ability of autoreactive T cells to induce CNS autoimmunity is impaired, most probably because of an inefficient T-cell transmigration into the CNS and defective CNS resident microglial function.

Mast cells (MCs) are best known as key immune players in immunoglobulin E (IgE)-dependent allergic reactions. In recent years, several lines of evidence have suggested that MCs might play an important role in several pathological conditions, including autoimmune disorders such as multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Since their first description in MS plaques in the late 1800s, much effort has been put into elucidating the contribution of MCs to the development of central nervous system (CNS) autoimmunity. Mouse models of MC-deficiency have provided a valuable experimental tool for dissecting MC involvement in MS and EAE. However, to date there is still major controversy concerning the function of MCs in these diseases. Indeed, although MCs have been classically proposed as having a detrimental and pro-inflammatory role, recent literature has questioned and resized the contribution of MCs to the pathology of MS and EAE. In this review, we will present the main evidence obtained in MS and EAE on this topic, and discuss the critical and controversial aspects of such evidence.

Mast cell (MC)-deficient c-Kit mutant Kit(W/W-v) mice are protected against experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, suggesting a detrimental role for MCs in this disease. To further investigate the role of MCs in EAE, we took advantage of a recently characterized model of MC deficiency, Kit(W-sh/W-sh). Surprisingly, we observed that myelin oligodendrocyte glycoprotein (MOG)(35-55)-induced chronic EAE was exacerbated in Kit(W-sh/W-sh) compared with Kit(+/+) mice. Kit(W-sh/W-sh) mice showed more inflammatory foci in the central nervous system (CNS) and increased T-cell response against myelin. To understand whether the discrepant results obtained in Kit(W-sh/W-sh) and in Kit(W/W-v) mice were because of the different immunization protocols, we induced EAE in these two strains with varying doses of MOG(35-55) and adjuvants. Although Kit(W-sh/W-sh) mice exhibited exacerbated EAE under all immunization protocols, Kit(W/W-v) mice were protected from EAE only when immunized with high, but not low, doses of antigen and adjuvants. Kit(W-sh/W-sh) mice reconstituted systemically, but not in the CNS, with bone marrow-derived MCs still developed exacerbated EAE, indicating that protection from disease could be exerted by MCs mainly in the CNS, and/or by other cells possibly dysregulated in Kit(W-sh/W-sh) mice. In summary, these data suggest to reconsider MC contribution to EAE, taking into account the variables of using different experimental models and immunization protocols.

Histamine may contribute to the pathology of MS and its animal model EAE. We explored the effects of histamine and specific HR agonists on activation and migratory capacity of myelin-autoreactive T cells. We show that histamine in vitro inhibits proliferation and IFN-γ production of mouse T cells activated against PLP(139-151). These effects were mimicked by the H1R agonist HTMT and the H2R agonist dimaprit and were associated with reduced activation of ERK½ kinase and with increased levels of cell cycle inhibitor p27Kip-1, both involved in T cell proliferation and anergy. H1R and H2R agonists reduced spontaneous and chemokine-induced adhesion of autoreactive T cells to ICAM-1 in vitro and blocked firm adhesion of these cells in inflamed brain microcirculation in vivo. Thus histamine, through H1R and H2R, inhibits activation of myelin-autoreactive T cells and their ability to traffic through the inflamed BBB. Strategies aimed at interfering with the histamine axis might have relevance in the therapy of autoimmune disease of the CNS.

The development of inflammatory diseases implies inactivation of regulatory T (Treg) cells through mechanisms that still are largely unknown. Here we showed that mast cells (MCs), an early source of inflammatory mediators, are able to counteract Treg inhibition over effector T cells. To gain insight into the molecules involved in their interplay, we set up an in vitro system in which all 3 cellular components were put in contact. Reversal of Treg suppression required T cell-derived interleukin-6 (IL-6) and the OX40/OX40L axis. In the presence of activated MCs, concomitant abundance of IL-6 and paucity of Th1/Th2 cytokines skewed Tregs and effector T cells into IL-17-producing T cells (Th17). In vivo analysis of lymph nodes hosting T-cell priming in experimental autoimmune encephalomyelitis revealed activated MCs, Tregs, and Th17 cells displaying tight spatial interactions, further supporting the occurrence of an MC-mediated inhibition of Treg suppression in the establishment of Th17-mediated inflammatory responses.

Induction of T helper 1 (Th1) to Th2 deviation through administration of self- or altered self-peptides holds promise for treatment of autoimmunity. However, administration of self-peptides in models of autoimmunity can result in anaphylactic reactions. Although both IgE and IgG1 antibodies might be involved in the development of anaphylaxis to myelin peptides in experimental autoimmune encephalomyelitis in mice, the effector cells and molecules involved are not fully understood. Here we show that systemic anaphylaxis to the self-antigen myelin oligodendrocyte glycoprotein (MOG) 35-55 can occur in mice lacking mast cells (Kit(W)/Kit(W-v) mice) or histamine (histidine decarboxylase-deficient mice), but is prevented in mice lacking IL-4. Treatment of mice with CV6209, a platelet-activating factor antagonist, slightly reduced the incidence of anaphylaxis to self-MOG35-55 in this model, but more effectively protected mice against anaphylaxis to this peptide when self-MOG35-55 was administered in a different immunization protocol that omitted the use of Bordetella pertussis toxin as an adjuvant at the time of immunization. Thus, anaphylactic reactions to self-MOG can occur in the absence of mast cells or histamine, key elements of the classical IgE-, mast cell-, and histamine-dependent pathway of anaphylaxis.

Erythropoietin (EPO) is of great interest as a therapy for many of the central nervous system (CNS) diseases and its administration is protective in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Endogenous EPO is induced by hypoxic/ischemic injury, but little is known about its expression in other CNS diseases. We report here that EPO expression in the spinal cord is induced in mouse models of chronic or relapsing-remitting EAE, and is prominently localized to motoneurons. We found a parallel increase of hypoxia-inducible transcription factor (HIF)-1 alpha, but not HIF-2 alpha, at the mRNA level, suggesting a possible role of non-hypoxic factors in EPO induction. EPO mRNA in the spinal cord was co-expressed with interferon (IFN)-gamma and tumor necrosis factor (TNF), and these cytokines inhibited EPO production in vitro in both neuronal and glial cells. Given the known inhibitory effect of EPO on neuroinflammation, our study indicates that EPO should be viewed as part of the inflammatory/anti-inflammatory network in MS.

There is considerable evidence that multiple sclerosis (MS) is an immune-mediated disease characterized by infiltration of inflammatory cells into the CNS and demyelination. Several myelin proteins may be encephalitogenic, including myelin basic protein, proteolipid protein and myelin oligodendrocyte glycoprotein (MOG), the latter being expressed on the external layer of myelin sheaths and hence accessible to antibody attack. We investigated MOG autoreactivity in serum and cerebrospinal fluid (CSF) by ELISA, employing the recombinant extracellular domain of MOG as antigen. We tested serum samples from 262 MS patients (175 relapsing-remitting, 43 primary progressive and 44 secondary progressive), 131 patients with other neurological diseases (OND) and 307 healthy controls. No patients or controls were receiving immunomodulating treatments. We found anti-MOG antibodies in the serum of 13.7% MS patients, mainly in those with secondary progressive MS (25%), in 13.7% of OND patients and in 6.2% of controls. We found a direct correlation (R(2) = 0.6, P = 0.002) between disease severity and anti-MOG titer only in patients with primary and secondary progressive MS. Anti-MOG antibodies were present in the CSF of 11.4% MS patients and 18.9% OND patients. Intrathecal synthesis of anti-MOG antibodies was demonstrated in four (4.5%) of MS patients and no OND patients. Anti-MOG antibodies are not specific for MS; however, they may characterize a subset of MS patients and this may be revealed by serial assays in relation to changing disease phase.

The diversity of autoimmune responses poses a formidable challenge to the development of antigen-specific tolerizing therapy. We developed 'myelin proteome' microarrays to profile the evolution of autoantibody responses in experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis (MS). Increased diversity of autoantibody responses in acute EAE predicted a more severe clinical course. Chronic EAE was associated with previously undescribed extensive intra- and intermolecular epitope spreading of autoreactive B-cell responses. Array analysis of autoantigens targeted in acute EAE was used to guide the choice of autoantigen cDNAs to be incorporated into expression plasmids so as to generate tolerizing vaccines. Tolerizing DNA vaccines encoding a greater number of array-determined myelin targets proved superior in treating established EAE and reduced epitope spreading of autoreactive B-cell responses. Proteomic monitoring of autoantibody responses provides a useful approach to monitor autoimmune disease and to develop and tailor disease- and patient-specific tolerizing DNA vaccines.

Background: Insulin dependent (i.e., "type 1") diabetes mellitus (T1DM) is considered to be a T cell mediated disease in which TH1 and Tc autoreactive cells attack the pancreatic islets. Among the beta-cell antigens implicated in T1DM, glutamic acid decarboxylase (GAD) 65 appears to play a key role in the development of T1DM in humans as well as in non-obese diabetic (NOD) mice, the experimental model for this disease. It has been shown that shifting the immune response to this antigen from TH1 towards TH2, via the administration of GAD65 peptides to young NOD mice, can suppress the progression to overt T1DM. Accordingly, various protocols of "peptide immunotherapy" of T1DM are under investigation. However, in mice with experimental autoimmune encephalomyelitis (EAE), another autoimmune TH1 mediated disease that mimics human multiple sclerosis, anaphylactic shock can occur when the mice are challenged with certain myelin self peptides that initially were administered with adjuvant to induce the disease., Results: Here we show that NOD mice, that spontaneously develop T1DM, can develop fatal anaphylactic reactions upon challenge with preparations of immunodominant GAD65 self peptides after immunization with these peptides to modify the development of T1DM., Conclusions: These findings document severe anaphylaxis to self peptide preparations used in an attempt to devise immunotherapy for a spontaneous autoimmune disease. Taken together with the findings in EAE, these results suggest that peptide therapies designed to induce a TH1 to TH2 shift carry a risk for the development of anaphylactic reactivity to the therapeutic peptides.

Analysis of mRNA from multiple sclerosis lesions revealed increased amounts of transcripts for several genes encoding molecules traditionally associated with allergic responses, including prostaglandin D synthase, histamine receptor type 1 (H1R), platelet activating factor receptor, Ig Fc epsilon receptor 1 (Fc epsilon RI), and tryptase. We now demonstrate that, in the animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), mediated by T helper 1 (Th1) T cells, histamine receptor 1 and 2 (H1R and H2R) are present on inflammatory cells in brain lesions. Th1 cells reactive to myelin proteolipid protein expressed more H1R and less H2R than Th2 cells. Pyrilamine, an H1R antagonist, blocked EAE, and the platelet activating factor receptor antagonist CV6209 reduced the severity of EAE. EAE severity was also decreased in mice with disruption of the genes encoding Ig Fc gamma RIII or both Fc gamma RIII and Fc epsilon RI. Prostaglandin D synthase and tryptase transcripts were elevated in EAE brain. Taken together, these data reveal extensive involvement of elements of the immune response associated with allergy in autoimmune demyelination. The pathogenesis of demyelination must now be viewed as encompassing elements of both Th1 responses and "allergic" responses.

Microarray analysis of multiple sclerosis (MS) lesions obtained at autopsy revealed increased transcripts of genes encoding inflammatory cytokines, particularly interleukin-6 and -17, interferon-gamma and associated downstream pathways. Comparison of two poles of MS pathology--acute lesions with inflammation versus 'silent' lesions without inflammation--revealed differentially transcribed genes. Some products of these genes were chosen as targets for therapy of experimental autoimmune encephalomyelitis (EAE) in mice. Granulocyte colony-stimulating factor is upregulated in acute, but not in chronic, MS lesions, and the effect on ameliorating EAE is more pronounced in the acute phase, in contrast to knocking out the immunoglobulin Fc receptor common gamma chain where the effect is greatest on chronic disease. These results in EAE corroborate the microarray studies on MS lesions. Large-scale analysis of transcripts in MS lesions elucidates new aspects of pathology and opens possibilities for therapy.

An expanded polyglutamine domain in huntingtin underlies the pathogenic events in Huntington disease (HD), characterized by chorea, dementia and severe weight loss, culminating in death. Transglutaminase (TGase) may be critical in the pathogenesis, via cross-linking huntingtin. Administration of the TGase competitive inhibitor, cystamine, to transgenic mice expressing exon 1 of huntingtin containing an expanded polyglutamine repeat, altered the course of their HD-like disease. Cystamine given intraperitoneally entered brain where it inhibited TGase activity. When treatment began after the appearance of abnormal movements, cystamine extended survival, reduced associated tremor and abnormal movements and ameliorated weight loss. Treatment did not influence the appearance or frequency of neuronal nuclear inclusions. Unexpectedly, cystamine treatment increased transcription of one of the two genes shown to be neuroprotective for polyglutamine toxicity in Drosophila, dnaj (also known as HDJ1 and Hsp40 in humans and mice, respectively). Inhibition of TGase provides a new treatment strategy for HD and other polyglutamine diseases.

Multiple sclerosis is a demyelinating disease, characterized by inflammation in the brain and spinal cord, possibly due to autoimmunity. Large-scale sequencing of cDNA libraries, derived from plaques dissected from brains of patients with multiple sclerosis (MS), indicated an abundance of transcripts for osteopontin (OPN). Microarray analysis of spinal cords from rats paralyzed by experimental autoimmune encephalomyelitis (EAE), a model of MS, also revealed increased OPN transcripts. Osteopontin-deficient mice were resistant to progressive EAE and had frequent remissions, and myelin-reactive T cells in OPN-/- mice produced more interleukin 10 and less interferon-gamma than in OPN+/+ mice. Osteopontin thus appears to regulate T helper cell-1 (TH1)-mediated demyelinating disease, and it may offer a potential target in blocking development of progressive MS.