Discontinuation of treatment with IFN-beta leads to exacerbation of experimental autoimmune encephalomyelitis in Lewis rats. Rapid reversal of the antiproliferative activity of IFN-beta and excessive expansion of autoreactive T cells as disease promoting mechanisms

Anti-inflammatory and cognitive effects of interferon-β1a (IFNβ1a) in a rat model of Alzheimer's disease

Background

Aβ_1-42 peptide abnormal production is associated with the development and maintenance of neuroinflammation and oxidative stress in brains from Alzheimer disease (AD) patients. Suppression of neuroinflammation may then represent a suitable therapeutic target in AD. We evaluated the efficacy of IFNβ1a in attenuating cognitive impairment and inflammation in an animal model of AD.

Methods

A rat model of AD was obtained by intra-hippocampal injection of Aβ_1-42 peptide (23 μg/2 μl). After 6 days, 3.6 μg of IFNβ1a was given subcutaneously (s.c.) for 12 days. Using the novel object recognition (NOR) test, we evaluated changes in cognitive function. Measurement of pro-inflammatory or anti-inflammatory cytokines, reactive oxygen species (ROS), and SOD activity levels was performed in the hippocampus. Data were evaluated by one-way ANOVA with Fisher’s Protected Least Significant Difference (PLSD) test.

Results

We showed that treatment with IFNβ1a was able to reverse memory impairment and to counteract microglia activation and upregulation of pro-inflammatory cytokines (IL-6, IL-1β) in the hippocampus of Aβ_1-42-injected rats. The anti-inflammatory cytokine IL-10, significantly reduced in the Aβ_1-42 animals, recovered to control levels following IFNβ1a treatment. IFNβ1a also reduced ROS and lipids peroxidation and increased SOD1 protein levels in the hippocampus of Aβ_1-42-injected rats.

Conclusion

This study shows that IFNβ1a is able to reverse the inflammatory and cognitive effects of intra-hippocampal Aβ_1-42 in the rat. Given the role played by inflammation in AD pathogenesis and the established efficacy of IFNβ1a in the treatment of inflammatory diseases of the central nervous system such as multiple sclerosis, its use may be a viable strategy to inhibit the pro-inflammatory cytokine and oxidative stress cascade associated with Aβ deposition in the hippocampus of AD patients.

Enhanced in vivo efficacy of a type I interferon superagonist with extended plasma half-life in a mouse model of multiple sclerosis

IFNβ is a common therapeutic option to treat multiple sclerosis. It is unique among the family of type I IFNs in that it binds to the interferon receptors with high affinity, conferring exceptional biological properties. We have previously reported the generation of an interferon superagonist (dubbed YNSα8) that is built on the backbone of a low affinity IFNα but modified to exhibit higher receptor affinity than even for IFNβ. Here, YNSα8 was fused with a 600-residue hydrophilic, unstructured N-terminal polypeptide chain comprising proline, alanine, and serine (PAS) to prolong its plasma half-life via "PASylation." PAS-YNSα8 exhibited a 10-fold increased half-life in both pharmacodynamic and pharmacokinetic assays in a transgenic mouse model harboring the human receptors, notably without any detectable loss in biological potency or bioavailability. This long-lived superagonist conferred significantly improved protection from MOG35-55-induced experimental autoimmune encephalomyelitis compared with IFNβ, despite being injected with a 4-fold less frequency and at an overall 16-fold lower dosage. These data were corroborated by FACS measurements showing a decrease of CD11b(+)/CD45(hi) myeloid lineage cells detectable in the CNS, as well as a decrease in IBA(+) cells in spinal cord sections determined by immunohistochemistry for PAS-YNSα8-treated animals. Importantly, PAS-YNSα8 did not induce antibodies upon repeated administration, and its biological efficacy remained unchanged after 21 days of treatment. A striking correlation between increased levels of CD274 (PD-L1) transcripts from spleen-derived CD4(+) cells and improved clinical response to autoimmune encephalomyelitis was observed, indicating that, at least in this mouse model of multiple sclerosis, CD274 may serve as a biomarker to predict the effectiveness of IFN therapy to treat this complex disease.

C16 peptide shown to prevent leukocyte infiltration and alleviate detrimental inflammation in acute allergic encephalomyelitis model

Integrins are important adhesion receptors for leukocytes binding to endothelial cellular adhesion molecules. Previous studies have suggested that blocking relevant integrins might prevent leukocyte infiltration and suppress clinical and pathological features of neuroinflammatory disease. Experimental autoimmune encephalomyelitis (EAE), a rodent model of Multiple sclerosis (MS), is characterized by chronic inflammatory disorder of the central nervous system in which circulating leukocytes enter the brain and spinal cord leading to inflammation, myelin damage and subsequent paralysis. To prove this hypothesis and explore a promising application for MS treatment, the effects of C16, an ανβ3 integrin-binding peptide, were tested in vitro and in vivo by transendothelial assay, electron microscopy observation, multiple histological and immunohistochemical staining. The results showed C16 inhibited transendothelial migration of the C8166-CD4 lymphoblast cells, and alleviated extensive spinal cord and brain infiltration of leukocytes and macrophages in the EAE model. Furthermore, a significant amelioration of astrogliosis and a dramatic decrease in demyelination and axonal loss were observed in C16 treated animals. The attenuating inflammatory progression may improve the regional environment and trigger further neuroprotective effects on myelin and axons, all this suggests that C16 peptide may be a promising therapeutic agent for multiple sclerosis.

Rescue from acute neuroinflammation by pharmacological chemokine-mediated deviation of leukocytes

Background

Neutrophil influx is an important sign of hyperacute neuroinflammation, whereas the entry of activated lymphocytes into the brain parenchyma is a hallmark of chronic inflammatory processes, as observed in multiple sclerosis (MS) and its animal models of experimental autoimmune encephalomyelitis (EAE). Clinically approved or experimental therapies for neuroinflammation act by blocking leukocyte penetration of the blood brain barrier. However, in view of unsatisfactory results and severe side effects, complementary therapies are needed. We have examined the effect of chlorite-oxidized oxyamylose (COAM), a potent antiviral polycarboxylic acid on EAE.

Methods

EAE was induced in SJL/J mice by immunization with spinal cord homogenate (SCH) or in IFN-γ-deficient BALB/c (KO) mice with myelin oligodendrocyte glycoprotein peptide (MOG_35-55). Mice were treated intraperitoneally (i.p.) with COAM or saline at different time points after immunization. Clinical disease and histopathology were compared between both groups. IFN expression was analyzed in COAM-treated MEF cell cultures and in sera and peritoneal fluids of COAM-treated animals by quantitative PCR, ELISA and a bioassay on L929 cells. Populations of immune cell subsets in the periphery and the central nervous system (CNS) were quantified at different stages of disease development by flow cytometry and differential cell count analysis. Expression levels of selected chemokine genes in the CNS were determined by quantitative PCR.

Results

We discovered that COAM (2 mg i.p. per mouse on days 0 and 7) protects significantly against hyperacute SCH-induced EAE in SJL/J mice and MOG_35-55-induced EAE in IFN-γ KO mice. COAM deviated leukocyte trafficking from the CNS into the periphery. In the CNS, COAM reduced four-fold the expression levels of the neutrophil CXC chemokines KC/CXCL1 and MIP-2/CXCL2. Whereas the effects of COAM on circulating blood and splenic leukocytes were limited, significant alterations were observed at the COAM injection site.

Conclusions

These results demonstrate novel actions of COAM as an anti-inflammatory agent with beneficial effects on EAE through cell deviation. Sequestration of leukocytes in the non-CNS periphery or draining of leukocytes out of the CNS with the use of the chemokine system may thus complement existing treatment options for acute and chronic neuroinflammatory diseases.

Experimental autoimmune encephalomyelitis (EAE) as a model for multiple sclerosis (MS)

Experimental autoimmune encephalomyelitis (EAE) is the most commonly used experimental model for the human inflammatory demyelinating disease, multiple sclerosis (MS). EAE is a complex condition in which the interaction between a variety of immunopathological and neuropathological mechanisms leads to an approximation of the key pathological features of MS: inflammation, demyelination, axonal loss and gliosis. The counter-regulatory mechanisms of resolution of inflammation and remyelination also occur in EAE, which, therefore can also serve as a model for these processes. Moreover, EAE is often used as a model of cell-mediated organ-specific autoimmune conditions in general. EAE has a complex neuropharmacology, and many of the drugs that are in current or imminent use in MS have been developed, tested or validated on the basis of EAE studies. There is great heterogeneity in the susceptibility to the induction, the method of induction and the response to various immunological or neuropharmacological interventions, many of which are reviewed here. This makes EAE a very versatile system to use in translational neuro- and immunopharmacology, but the model needs to be tailored to the scientific question being asked. While creating difficulties and underscoring the inherent weaknesses of this model of MS in straightforward translation from EAE to the human disease, this variability also creates an opportunity to explore multiple facets of the immune and neural mechanisms of immune-mediated neuroinflammation and demyelination as well as intrinsic protective mechanisms. This allows the eventual development and preclinical testing of a wide range of potential therapeutic interventions.

Interferon regulatory factor-7 modulates experimental autoimmune encephalomyelitis in mice

Background

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS) with unknown etiology. Interferon-β (IFN-β), a member of the type I IFN family, is used as a therapeutic for MS and the IFN signaling pathway is implicated in MS susceptibility. Interferon regulatory factor 7 (IRF7) is critical for the induction and positive feedback regulation of type I IFN. To establish whether and how endogenous type I IFN signaling contributes to disease modulation and to better understand the underlying mechanism, we examined the role of IRF7 in the development of MS-like disease in mice.

Methods

The role of IRF7 in development of EAE was studied by immunizing IRF7-KO and C57BL/6 (WT) mice with myelin oligodendrocyte glycoprotein using a standard protocol for the induction of EAE. We measured leukocyte infiltration and localization in the CNS using flow cytometric analysis and immunohistochemical procedures. We determined levels of CD3 and selected chemokine and cytokine gene expression by quantitative real-time PCR.

Results

IRF7 gene expression increased in the CNS as disease progressed. IRF7 message was localized to microglia and infiltrating leukocytes. Furthermore, IRF7-deficient mice developed more severe disease. Flow cytometric analysis showed that the extent of leukocyte infiltration into the CNS was higher in IRF7-deficient mice with significantly higher number of infiltrating macrophages and T cells, and the distribution of infiltrates within the spinal cord was altered. Analysis of cytokine and chemokine gene expression by quantitative real-time PCR showed significantly greater increases in CCL2, CXCL10, IL-1β and IL17 gene expression in IRF7-deficient mice compared with WT mice.

Conclusion

Together, our findings suggest that IRF7 signaling is critical for regulation of inflammatory responses in the CNS.

Animal models of multiple sclerosis--potentials and limitations

Experimental autoimmune encephalomyelitis (EAE) is still the most widely accepted animal model of multiple sclerosis (MS). Different types of EAE have been developed in order to investigate pathogenetic, clinical and therapeutic aspects of the heterogenic human disease. Generally, investigations in EAE are more suitable for the analysis of immunogenetic elements (major histocompatibility complex restriction and candidate risk genes) and for the study of histopathological features (inflammation, demyelination and degeneration) of the disease than for screening of new treatments. Recent studies in new EAE models, especially in transgenic ones, have in connection with new analytical techniques such as microarray assays provided a deeper insight into the pathogenic cellular and molecular mechanisms of EAE and potentially of MS. For example, it was possible to better delineate the role of soluble pro-inflammatory (tumor necrosis factor-α, interferon-γ and interleukins 1, 12 and 23), anti-inflammatory (transforming growth factor-β and interleukins 4, 10, 27 and 35) and neurotrophic factors (ciliary neurotrophic factor and brain-derived neurotrophic factor). Also, the regulatory and effector functions of distinct immune cell subpopulations such as CD4+ Th1, Th2, Th3 and Th17 cells, CD4+FoxP3+ Treg cells, CD8+ Tc1 and Tc2, B cells and γδ+ T cells have been disclosed in more detail. The new insights may help to identify novel targets for the treatment of MS. However, translation of the experimental results into the clinical practice requires prudence and great caution.

Effects of human recombinant-interferon β in experimental autoimmune encephalomyelitis in guinea pigs

CONTEXT

Although clinical data for beneficial effects of Betaferon, human recombinant-interferon (r-IFN) β-1b, are accumulating, what is less evident is how and why it works.

OBJECTIVE

The present study was carried out to examine whether Betaferon suppresses progression of experimental autoimmune encephalomyelitis (EAE).

MATERIALS AND METHODS

The EAE model was employed in guinea pigs in vivo, and mononuclear cell proliferation and 2',5'-oligoadenylate synthetase activity were assessed in vitro.

RESULTS

Betaferon was more reactive in two assays of guinea pigs, mitogen-induced proliferation of peripheral blood mononuclear cells and 2',5'-oligoadenylate synthetase activity of blood, than in rats and rabbits. Guinea pigs were immunized actively by antigen, porcine myelin basic protein. The neurological deficits were assessed by clinical signs scored daily. Guinea pig Betaferon, replaced with guinea pig albumin (GPA), at 1.2 and 12.0 MIU/kg/day or vehicle was administered subcutaneously daily for 20 days in the immunized guinea pigs. GPA-Betaferon suppressed the manifestation of ataxia or more progression of chronic neurological deficits significantly at 1.2 MIU/kg (p <0.05). Two out of 10 animals manifested no clinical signs in the GPA-Betaferon-treated group with the higher dose, while all animals were worsened with typical clinical signs of EAE in the vehicle group where mononuclear cell infiltrates around blood vessels were seen in the spinal cord of vehicle-treated animals.

DISCUSSION AND CONCLUSION

Human r-IFN β-1b attenuates progression of neurological deficits in the EAE model of guinea pigs with evidence for higher susceptibility of animal cells/tissues to the human cytokine, in contrast with rodents and rabbits.

Mouse models for multiple sclerosis: historical facts and future implications

Multiple sclerosis (MS) is an inflammatory and demyelinating condition of the CNS, characterized by perivascular infiltrates composed largely of T lymphocytes and macrophages. Although the precise cause remains unknown, numerous avenues of research support the hypothesis that autoimmune mechanisms play a major role in the development of the disease. Pathologically similar lesions to those seen in MS can be induced in laboratory rodents by immunization with CNS-derived antigens. This form of disease induction, broadly termed experimental autoimmune encephalomyelitis, is frequently the starting point in MS research with respect to studying pathogenesis and creating novel treatments. Many different EAE models are available, each mimicking a particular facet of MS. These models all have common ancestry, and have developed from a single concept of immunization with self-antigen. We will discuss the major changes in immunology research, which have shaped the EAE models we use today, and discuss how current animal models of MS have resulted in successful treatments and more open questions for researchers to address.

Experimental autoimmune encephalomyelitis in Lewis rats: IFN-beta acts as a tolerogenic adjuvant for induction of neuroantigen-dependent tolerance

Cytokine-Ag fusion proteins represent a novel approach for induction of Ag-specific tolerance and may constitute an efficient therapy for autoimmune disease. This study addressed whether a fusion protein containing rat IFN-beta and the encephalitogenic 73-87 determinant of myelin basic protein (i.e., the neuroantigen, or NAg) could prevent or treat experimental autoimmune encephalomyelitis (EAE) in Lewis rats. The optimal structure of the fusion protein was comprised of the rat IFN-beta cytokine as the N-terminal domain with an enterokinase (EK) linker to the NAg domain. Both cytokine and NAg domains had full biological activity. Subcutaneous administration of 1 nmol of IFNbeta-NAg fusion protein in saline on days -21, -14, and -7 before encephalitogenic challenge on day 0 resulted in a substantial attenuation of EAE. In contrast, administration of IFN-beta or NAg alone did not affect susceptibility to EAE. The covalent attachment of IFN-beta and NAg was not necessary, because separate injections of IFN-beta and NAg at adjacent sites were as effective as injection of IFNbeta-NAg for prevention of disease. When treatment was initiated after disease onset, the rank order of inhibitory activity was as follows: the IFNbeta-NAg fusion protein > or = a mixture of IFN-beta plus NAg > IFN-beta > NAg. The novel finding that IFN-beta acts as a tolerogenic adjuvant as well as a tolerogenic fusion partner may have significance for development of tolerogenic vaccines.

Animal models of multiple sclerosis for the development and validation of novel therapies - potential and limitations

Various types of experimental autoimmune encephalomyelitis (EAE) reflect some of the pathogenetic, clinical, and therapeutic features of the different forms of multiple sclerosis (MS), thereby, providing some, albeit limited, insight into the molecular and cellular basis of the human disease. Specific questions of MS therapy including the search for new therapeutic targets and strategies and their validation require investigations in different available EAE models. A survey is given of experimental therapeutic approaches that are currently under study with the most promising examples of monoclonal antibodies, gene therapy, stem cell transplantation and orally applied small molecular weight disease-modifying drugs. Reasons for therapy failure and adverse side-effects of some experimental trials are discussed. Precaution is advised, if results of new experimental approaches are translated into clinical practice.

Flupirtine as neuroprotective add-on therapy in autoimmune optic neuritis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system that results in persistent impairment in young adults. During chronic progressive disease stages, there is a strong correlation between neurodegeneration and disability. Current therapies fail to prevent progression of neurological impairment during these disease stages. Flupirtine, a drug approved for oral use in patients suffering from chronic pain, was used in a rat model of autoimmune optic neuritis and significantly increased the survival of retinal ganglion cells, the neurons that form the axons of the optic nerve. When flupirtine was combined with interferon-beta, an established immunomodulatory therapy for MS, visual functions of the animals were improved during the acute phase of optic neuritis. Furthermore, flupirtine protected retinal ganglion cells from degeneration in a noninflammatory animal model of optic nerve transection. Although flupirtine was shown previously to increase neuronal survival by Bcl-2 up-regulation, this mechanism does not appear to play a role in flupirtine-mediated protection of retinal ganglion cells either in vitro or in vivo. Instead, we showed through patch-clamp investigations that the activation of inwardly rectifying potassium channels is involved in flupirtine-mediated neuroprotection. Considering the few side effects reported in patients who receive long-term flupirtine treatment for chronic pain, our results indicate that this drug is an interesting candidate for further evaluation of its neuroprotective potential in MS.

A fusion protein consisting of IL-16 and the encephalitogenic peptide of myelin basic protein constitutes an antigen-specific tolerogenic vaccine that inhibits experimental autoimmune encephalomyelitis

To test a novel concept for the generation of tolerogenic vaccines, fusion proteins were constructed encompassing a tolerogenic or biasing cytokine and the major encephalitogenic peptide of guinea pig myelin basic protein (GPMBP; i.e., neuroantigen or NAg). The cytokine domain was predicted to condition APC while simultaneously targeting the covalently linked encephalitogenic peptide to the MHC class II Ag processing pathway of those conditioned APC. Rats were given three s.c. injections of cytokine-NAg in saline 1-2 wk apart and then at least 1 wk later were challenged with NAg in CFA. The rank order of tolerogenic activity in the Lewis rat model of EAE was NAgIL16 > IL2NAg > IL1RA-NAg, IL13NAg >or= IL10NAg, GPMBP, GP69-88, and saline. NAgIL16 was also an effective inhibitor of experimental autoimmune encephalomyelitis when administered after an encephalitogenic challenge during the onset of clinical signs. Covalent linkage of the NAg and IL-16 was required for inhibition of experimental autoimmune encephalomyelitis. These data identify IL-16 as an optimal cytokine partner for the generation of tolerogenic vaccines and indicate that such vaccines may serve as Ag-specific tolerogens for the treatment of autoimmune disease.

Beta-interferon unbalances the peripheral T cell proinflammatory response in experimental autoimmune encephalomyelitis

Interferon beta (IFNbeta) is a widespread therapy for multiple sclerosis (MS). We have analyzed some critical features of the T cell activation process in lymph nodes after IFNbeta treatment of experimental autoimmune encephalomyelitis (EAE) in SJL mice. Prevention of clinical signs and drastic reduction of perivascular infiltrates in the central nervous system (CNS) were accompanied by alterations in nuclear DNA binding activity levels of NFkappaB and Stat6 transcription factors in lymph node cells (LNC). A decrease of active NFkappaB subunits in treated animals correlated with lower levels of the cytoplasmic phosphorylated form of IkappaBalpha. Results also showed that nuclear DNA binding activity of Stat6 was increased by IFNbeta treatment, as were the cytoplasmic levels of phosphorilated Stat6 (P-Stat6). These high levels of P-Stat6 in IFNbeta-treated animals were accompanied by an increase of IL-4 expression levels measured by real time PCR. In vitro experiments with the IL-4 producing clone D10.G4.1 indicates that the IFNbeta-mediated IL-4 induction is not an effect exclusive to MBP-reactive cells, and suggest that it could be mediated by mRNA stability enlargement. On the other hand, IFNbeta treatment of EAE produced no significant changes in peripheral IFNgamma expression and a striking decrease of IL-17. These findings suggest that the inhibition of NFkappaB activity, the increase of IL-4 expression and its signaling transduction, and the decrease of IL-17 may cooperate to some of the antiinflammatory effects of IFNbeta on EAE.

Effects of glatiramer acetate and interferon-beta on neurodegeneration in a model of multiple sclerosis: a comparative study

Axonal destruction and neuronal loss occur early during multiple sclerosis (MS), an autoimmune inflammatory central nervous system disease that frequently manifests with acute optic neuritis. Glatiramer acetate (GA) and interferon-beta-1b (IFN-beta-1b) are two immunomodulatory agents that have been shown to decrease the frequency of MS relapses. However, the question of whether these substances can slow neurodegeneration in MS patients is the subject of controversy. In a rat model of experimental autoimmune encephalomyelitis, we investigated the effects of GA and IFN-beta-1b on the survival of retinal ganglion cells (RGCs), the neurons that form the axons of the optic nerve. For each substance, therapy was started 14 days before immunization, on the day of immunization, or on the day of clinical disease onset. After myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis became clinically manifest, optic neuritis was monitored by recording visual evoked potentials. The function of RGCs was measured by electroretinograms. Although early GA or IFN-beta-1b treatment showed benefit on disease activity, only treatment with GA exerted protective effects on RGCs, as revealed by measuring neurodegeneration and neuronal function. Furthermore, we demonstrate that this GA-induced neuroprotection does not exclusively depend on the reduction of inflammatory infiltrates within the optic nerve.

Effects of interferon-beta-1a on neuronal survival under autoimmune inflammatory conditions

Interferon-beta-1a (IFN-beta-1a) is an approved treatment for multiple sclerosis (MS). It improves the disease course by reducing the relapse rate as well as the persistent neurological deficits. Recent MRI and post-mortem studies revealed that neuronal and axonal damage are most relevant for chronic disability in MS patients. We have characterized previously time course and mechanisms of neuronal apoptosis in a rat model of myelin oligodendrocyte glycoprotein (MOG)-induced optic neuritis. In this animal model, application of IFN-beta-1a three times per week slightly decreases the loss of retinal ganglion cells (RGCs), the neurons that form the axons within the optic nerve. In contrast to neurotrophic factors, this cytokine does not directly protect cultured RGCs from apoptosis. We conclude that IFN-beta-1a is a suitable candidate to be combined with a directly neuroprotective agent in order to further decrease axonal and neuronal degeneration in MS patients.

Apoptotic Cell Death in Experimental Autoimmune Encephalomyelitis

Particularly in the vulnerable CNS with a low capacity for regeneration specialized mechanisms must be active for the fast and gentle elimination of dysregulated autoaggressive immune cells. In EAE, local apoptosis of autoimmune T-cells has been identified as a safe means for the removal of these unwanted cells. T-cell apoptosis in situ followed by phagocytic clearance of apoptotic remnants by glia assures a minimum of detrimental bystander damage to the local parenchyma and down-regulates the local inflammatory reaction. The pharmacological augmentation of local apoptosis of inflammatory effector cells might gain therapeutic importance also in human neuroimmunological diseases such as multiple sclerosis.

Laquinimod (ABR-215062) suppresses the development of experimental autoimmune encephalomyelitis, modulates the Th1/Th2 balance and induces the Th3 cytokine TGF-beta in Lewis rats

The new orally active drug laquinimod (ABR-215062) was evaluated in experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. EAE shares important immunological and clinical features with multiple sclerosis (MS). Doses of 16, 1.6 and 0.16 mg/kg/day laquinimod dose-dependently inhibited disease and showed better disease inhibitory effects as compared to roquinimex (Linomide). Furthermore, laquinimod inhibited the inflammation of both CD4+ T cells and macrophages into central nervous tissues, i.e. the spinal cord. It also changed the cytokine balance in favour of TH2/TH3 cytokines IL-4, IL-10 and TGF-beta. Laquinimod therefore represents a new orally active immunoregulatory drug without general immunosuppressive properties with a potential for the treatment of severe autoimmune diseases like MS.

Gene therapy for autoimmune diseases: quo vadis?

Biological therapies using antibodies and cytokines are becoming widespread for the treatment of chronic inflammatory autoimmune diseases. However, these treatments have several limitations - such as expense, the need for repeated injections and unwanted side-effects - that can be overcome by genetic delivery. This review summarizes the ingenuity, sophistication and variety of gene-therapy approaches that have been taken in the design of therapeutic molecules and vectors, the engineering of cells and the regulation of gene expression for the targeting of disease outcome. We focus our attention on multiple sclerosis, type 1 diabetes and rheumatoid arthritis.

Expression, purification, and characterization of rat interferon-β, and preparation of an N-terminally PEGylated form with improved pharmacokinetic parameters

To identify potential new clinical uses and routes of administration for human interferon-beta-1a (IFN-beta-1a), we have developed an expression and purification procedure for the preparation of highly purified rat interferon-beta (IFN-beta) suitable for testing in rat models of human disease. An expression vector containing the rat IFN-beta signal sequence and structural gene was constructed and transfected into Chinese hamster ovary (CHO) cells. The protein was purified from CHO cell conditioned medium and purified to > 99.5% purity using standard chromatographic techniques. Analytical characterization indicated that the protein was a heavily glycosylated monomeric protein, with two of the four predicted N-glycosylation sites occupied. Analysis of the attached oligosaccharides showed them to be a complex mixture of bi-antennary, tri-antennary, and tetra-antennary structures with a predominance of sialylated tri-antennary and tetra-antennary structures. Peptide mapping, N-terminal sequencing, and mass spectrometry confirmed the identity and integrity of the purified protein. The purified protein had a specific activity of 2.1x10(8)U/mg when assayed on rat RATEC cells, which is similar in magnitude to the potencies observed for murine IFN-beta and human IFN-beta-1a assayed on murine and human cells, respectively. We also prepared an N-terminally PEGylated form of rat IFN-beta in which a 20 kDa methoxy polyethylene glycol (PEG)-propionaldehyde was attached to the N-terminal alpha-amino group of Ile-1. The PEGylated protein, which retained essentially full in vitro antiviral activity, had improved pharmacokinetic parameters in rats as compared to the unmodified protein. Both the unmodified and PEGylated forms of rat IFN-beta will be useful for testing in rat models of human disease.

Interferon-beta blocks infiltration of inflammatory cells and reduces infarct volume after ischemic stroke in the rat

The inflammatory response that exacerbates cerebral injury after ischemia is an attractive therapeutic target: it progresses over days and strongly contributes to worsening of the neurologic outcome. The authors show that, after transient ischemic injury to the rat brain, systemic application of interferon-beta (IFN-beta), a cytokine with antiinflammatory properties, attenuated the development of brain infarction. Serial magnetic resonance imaging (MRI) showed that IFN-beta treatment reduced lesion volume on diffusion-weighted MRI by 70% (P < 0.01) at 1 day after stroke. IFN-beta attenuated the leakage of contrast agent through the blood-brain barrier (P < 0.005), indicating a better-preserved blood-brain barrier integrity. Both control and IFN-beta-treated animals showed a similar degree of relative hyperperfusion of the lesioned hemisphere, indicating that neuroprotection by IFN-beta was not mediated by improved cerebral perfusion as assessed 24 hours after stroke onset. IFN-beta treatment resulted in an 85% reduction (P < 0.0001) in infarct volume 3 weeks later, as determined from T2-weighted MRI and confirmed by histology. This effect was achieved even when treatment was started 6 hours after stroke onset. Quantitative immunohistochemistry at 24 hours after stroke onset showed that IFN-beta almost completely prevented the infiltration of neutrophils and monocytes into the brain. Gelatinase zymography showed that this effect was associated with a decrease in matrix metalloproteinase-9 expression. In conclusion, treatment with the antiinflammatory cytokine IFN-beta affords significant neuroprotection against ischemia/reperfusion injury, and within a relatively long treatment window. Because IFN-beta has been approved for clinical use, it may be rapidly tested in a clinical trial for its efficacy against human stroke.

Interferon-beta prevents cytokine-induced neutrophil infiltration and attenuates blood-brain barrier disruption

Inflammation can contribute to brain injury, such as that resulting from ischemia or trauma. The authors have previously shown that the cytokine interferon-beta (IFN-beta) affords protection against ischemic brain injury, which was associated with a diminished infiltration of neutrophils and a reduction in blood-brain barrier (BBB) disruption. The goal of the current study was to directly assess the effects of IFN-beta on neutrophil infiltration, with the use of an in vivo assay of neutrophil infiltration with relevance to ischemic brain injury. Intrastriatal injection of recombinant rat cytokine-induced neutrophil chemoattractant-1, a member of the interleukin-8 family (1 microg in 1 microl), triggered massive infiltration of neutrophils and extensive BBB disruption 6 hours later, as measured using immunofluorescence microscopy and magnetic resonance imaging in the rat, respectively. Depleting the animals of neutrophils before interleukin-8 injection prevented BBB disruption. Treatment with IFN-beta (5 x 106 U/kg) almost completely prevented neutrophil infiltration and attenuated BBB damage. Gelatinase zymography showed matrix metalloproteinase-9 expression in the ipsilateral striatum after interleukin-8 injection. Both neutrophil depletion and IFN-beta treatment downregulated matrix metalloproteinase-9. IFN-beta has already been approved for human use as a treatment for the chronic inflammatory disorder multiple sclerosis. The potential value of IFN-beta as a treatment that can attenuate acute brain inflammation is considered.

Erythropoietin exerts an anti-inflammatory effect on the CNS in a model of experimental autoimmune encephalomyelitis

In recent work we reported that systemically administered erythropoietin (EPO) crosses the blood-brain barrier and has protective effects in animal models of cerebral ischemia, brain trauma and in a rat model of experimental autoimmune encephalomyelitis (EAE). Here we characterize the effect of systemic EPO on the inflammatory component of actively induced, acute EAE in Lewis rats. Administration of EPO at doses of 500-5000 U/kg bw i.p., daily from day 3 after immunization with myelin basic protein (MBP), delayed the onset of EAE and decreased its clinical score at peak time (days 12-13). Immunohistochemical analysis of the spinal cord using anti-glial fibrillary acidic protein (GFAP) and anti-CD11b antibodies showed that EPO markedly diminished inflammation and glial activation/proliferation. EAE induced significant levels of TNF and IL-6 in the spinal cord, where IL-6 was maximum at the onset of the disease (day 10) and TNF at its peak (day 12). EPO delayed the increase of TNF levels, without altering their peak levels, and markedly reduced those of IL-6 suggesting that the decreased inflammation and clinical score may be in part upon attenuation of IL-6. On the other hand, EPO was without effect in a model of adjuvant-induced arthritis in Lewis rats, suggesting a specificity towards autoimmune demyelinating diseases. These data suggest that EPO might act as a protective cytokine in inflammatory pathologies of the CNS.

The new orally active immunoregulator laquinimod (ABR-215062) effectively inhibits development and relapses of experimental autoimmune encephalomyelitis

A new orally active drug, laquinimod (ABR-215062), was shown to completely inhibit the development of murine acute experimental autoimmune encephalomyelitis (EAE). Furthermore, leukocyte infiltration into the central nervous system (CNS) was abolished in the laquinimod-treated animals. By direct comparison based on dose and total exposure, laquinimod was approximately 20 times more potent than the immunomodulator roquinimex. Laquinimod also had clear therapeutic effect when given after clinical onset in a chronic relapsing EAE model. It therefore represents a new orally active immunoregulatory drug without general immunosuppressive properties for the treatment of the autoimmune disease multiple sclerosis.

Interferon-beta directly influences monocyte infiltration into the central nervous system

Interferon-beta (IFN-beta) has beneficial effects on the clinical symptoms of multiple sclerosis (MS) patients, but its exact mechanism of action is yet unknown. We here suggest that IFN-beta directly modulates inflammatory events at the level of cerebral endothelium. IFN-beta treatment resulted in a marked reduction of perivascular infiltrates in acute experimental allergic encephalomyelitis (EAE), the rat model for MS, which was coupled to a major decrease in the expression of the adhesion molecules ICAM-1 and VCAM-1 on brain capillaries. In vitro, IFN-beta reduced the mRNA levels and protein expression of adhesion molecules of brain endothelial cell cultures and diminished monocyte transendothelial migration. Monocyte adhesion and subsequent migration was found to be predominantly regulated by VCAM-1. These data indicate that IFN-beta exerts direct antiinflammatory effects on brain endothelial cells thereby contributing to reduced lesion formation as observed in MS patients.

Stress, the immune system and vulnerability to degenerative disorders of the central nervous system in transgenic mice expressing glucocorticoid receptor antisense RNA

Current research evidence suggests that interactions between genetic and environmental factors contribute to modulate the susceptibility to degenerative disorders, including inflammatory and autoimmune diseases of the central nervous system (CNS). In this context, bidirectional communication between the neuroendocrine and immune systems during ontogeny plays a pivotal role in programming the development of neuroendocrine and immune responses in adult life, thereby influencing the predisposition to several disease entities. Glucocorticoids (GCs), the end products of the hypothalamic-pituitary-adrenocortical (HPA) axis, gender and signals generated by hypothalamic-pituitary-gonadal (HPG) axis are major players coordinating the development of immune system function and exerting powerful effects in the susceptibility to autoimmune disorders, including experimental autoimmune encephalomyelitis (EAE), the experimental model for multiple sclerosis (MS). In particular, GCs exert their beneficial immunosuppressive and anti-inflammatory effects in inflammatory disorders of the CNS, after binding to their cytoplasmic receptors (GRs). Here we review our work using transgenic (Tg) mice with a dysfunctional GR from early embryonic life on programming vulnerability to EAE. The GR-deficiency of these Tg mice confers resistance to active EAE induction. The interplay between GCs, proinflammatory mediators, gender and EAE is summarized. On the basis of our data, it does appear that exposure to a defective GR through development programs major changes in endogenous neuroendocrine and immune mechanisms controlling the vulnerability to EAE. These studies highlight the plasticity of the HPA-immune axis and its pharmacological manipulation in autoimmune diseases of the CNS.

Glucocorticoid and type 1 interferon interactions at the blood-brain barrier: relevance for drug therapies for multiple sclerosis

The pharmacological effect of glucocorticoids and type 1 interferons (IFNs), simultaneously used as therapeuticals for multiple sclerosis (MS), on the (inflamed) blood-brain barrier (BBB) was investigated in vitro. Although both drugs additively decreased BBB permeability, they did not prevent the increase in BBB permeability induced by lipopolysaccharide (LPS), which served as a pro-inflammatory stimulus. The beneficial clinical effect of glucocorticoid and IFN therapy for MS seems there- fore not to be mediated through a direct action at the level of the BBB. Most strikingly, however, pretreatment with type 1 IFNs (alpha and beta) potentiated the effect of glucocorticoids by two orders of magnitude. This lead us to hypothesize that type 1 IFNs may restore the dysfunctional T-helper 1 (Th1)/Th2 balance associated with MS, by a mechanism that involves an increased sensitivity for glucocorticoids.

Beyond erythropoiesis: novel applications for recombinant human erythropoietin

Erythropoietin (EPO) primarily is produced in the kidney and acts as a principal mediator of the physiologic response to hypoxia by increasing red blood cell production. Astrocytes and neurons in the central nervous system (CNS) also are known to produce EPO in response to hypoxia/ischemia. EPO appears to play a neuroprotective role based on preclinical data demonstrating the ability of recombinant human erythropoietin (r-HuEPO) to shield neurons from hypoxic/ischemic stress when administered intracerebraventricularly. In CNS models, systemically administered r-HuEPO has not been intensely investigated because large glycosylated molecules generally were deemed incapable of crossing the blood-brain barrier (BBB). A collaborative research effort identified expression of EPO receptors on human brain capillaries and a specific receptor-mediated transport of r-HuEPO across the BBB after a single intraperitoneal (IP) injection in rodents, with subsequent protection against various types of neuronal damage. For example, administration of r-HuEPO 24 hours before or up to 6 hours after focal ischemic stroke significantly reduced the extent of infarction. r-HuEPO also attenuated concussive brain injury, kainate-induced seizure activity, and autoimmune encephalomyelitis. These preclinical findings suggest that r-HuEPO may have therapeutic potential for stroke, head trauma, and epilepsy; additional studies are needed to confirm and extend these encouraging observations in animal models.

Interferon-beta treatment of experimental autoimmune encephalomyelitis leads to rapid nonapoptotic termination of T cell infiltration

We investigated the possible mechanisms how interferon (IFN)-beta may control T cell infiltration in the CNS in experimental autoimmune encephalomyelitis (EAE). Adoptive transfer (AT) EAE was induced in groups of six female Lewis rats. Animals were treated with 3 x 10(5) units of recombinant rat IFN-beta s.c. once at 18 hr, or with 10 mg/kg methylprednisolone (MP) i.v. twice at 18 and 6 hr prior to dissection, or with a combination of both. T cell apoptosis was detected by immunohistochemistry on paraffin sections of spinal cord, using morphological criteria and TUNEL staining. Double labeling of immune cells was done for tumor necrosis factor (TNF)-alpha and metalloproteinase (MMP) 2. Disruption of the blood-brain barrier (BBB) was visualized by staining for albumin. In severe EAE, an increase of T cell apoptosis was seen after IFN-beta alone (all data presented as mean +/- SD: 24.5% +/- 2.2%, P < 0.05, vs. 19.4% +/- 3.1% in controls), and in combination with MP (29.4% +/- 7.3%, P < 0.05 vs. controls). Only the combination therapy decreased T cell infiltration (53.9 +/- 17.7 cells/mm(2), P < 0.05, vs. 99.5 +/- 35.2 cells/mm2 in controls). In moderate EAE, the rate of T cell apoptosis was slightly increased after IFN-beta (21.2% +/- 5.2% vs. 17.4% +/- 5.0% in controls), whereas MP alone (25.5% +/- 3.5%, P < 0.01 vs. controls) and the combination therapy (22.4% +/- 4.8%, P < 0.05 vs. controls) had a clear augmenting effect. IFN-beta tended to decrease T cell infiltration (46.1 +/- 12.7 cells/mm2) compared to controls (59.2 +/- 18.5 cells/mm2). The rate of TNF-alpha-expressing T cells was significantly decreased by IFN-beta and in combination with MP. Also, TNF-alpha expression in macrophages was significantly reduced by IFN-beta and by the combination therapy. The rate of MMP2-expressing macrophages was lower after IFN-beta but clearly decreased only in combination with MP. BBB disruption was ameliorated after IFN-beta but significantly only in combination with MP. Our study indicates that IFN-beta affects the immunopathological process in EAE in several ways, but apoptosis appears as a minor component. In view of treatment of MS relapses, the synergistic effects in this study corroborate the use of a combination therapy with high-dose MP and IFN-beta.

Interferon-β in multiple sclerosis: altering the balance of interleukin-12 and interleukin-10?

Interferon-beta is a remarkably pleiotropic molecule. Antiviral, pro- and antiproliferative, pro- and antiapoptotic, and complex immunoregulatory activities have all been described. The precise mechanism(s) that underlie the beneficial effects of interferon-beta in multiple sclerosis remain poorly understood; this has hindered progress in the search for more effective therapies. An increasing body of literature supports the hypothesis that interferon-beta-mediated changes in the production and activities of the immunoregulatory cytokines interleukin-12 and interleukin-10 are important to the therapeutic benefits of interferon-beta in multiple sclerosis. These data are reviewed here.

Effects of Linomide on immune cells and cytokines inhibit autoimmune pathologies of the central and peripheral nervous system

Linomide (roquinimex, LS 2616) is a quinoline-3-carboxamide with pleiotropic immune modulating capacity and it has therapeutic effects in several experimental animal models of autoimmune diseases. Linomide has been evaluated in clinical trials for multiple sclerosis, and was indeed shown to have disease inhibitory effects. However, due to unexpected side effects recorded in patients treated with Linomide, premature termination of clinical trials was required. The basic mechanism(s) of action of Linomide in inducing beneficial effects in autoimmune diseases is still elusive. Some experimental evidence indicates that Linomide influences the regulation of the cytokine profile, resulting in the inhibition of autoimmune and inflammation pathologies. This review focuses on Linomide applied in models for autoimmune and inflammation pathologies of the central and the peripheral nervous system, and summarises its very encouraging disease inhibitory effects and their potential pharmacological basis. The beneficial effects recorded with Linomide in both experimental and clinical trials emphasise the possible value of substances with Linomide-like activity for clinical use in autoimmune and inflammation pathologies in the near future.

Erythropoietin crosses the blood-brain barrier to protect against experimental brain injury

Erythropoietin (EPO), recognized for its central role in erythropoiesis, also mediates neuroprotection when the recombinant form (r-Hu-EPO) is directly injected into ischemic rodent brain. We observed abundant expression of the EPO receptor at brain capillaries, which could provide a route for circulating EPO to enter the brain. In confirmation of this hypothesis, systemic administration of r-Hu-EPO before or up to 6 h after focal brain ischemia reduced injury by approximately 50-75%. R-Hu-EPO also ameliorates the extent of concussive brain injury, the immune damage in experimental autoimmune encephalomyelitis, and the toxicity of kainate. Given r-Hu-EPO's excellent safety profile, clinical trials evaluating systemically administered r-Hu-EPO as a general neuroprotective treatment are warranted.

A new primate model for multiple sclerosis in the common marmoset

Experimental autoimmune encephalomyelitis (EAE) in outbred marmoset monkeys (Callithrix jacchus) is a recently developed nonhuman primate model of multiple sclerosis. Here, Bert 't Hart and colleagues compare this model to EAE in rhesus monkeys, highlighting autoimmune mechanisms in CNS inflammation and demyelination, including the role of major histocompatibility complex restriction and preclinical evaluation of innovative immunotherapies.

MRI and clinical activity in MS patients after terminating treatment with interferon beta-1b

Monthly MRI activity and clinical disability were evaluated in two relapsing-remitting multiple sclerosis (RRMS) patients for 4 years during a cross-over treatment trial with IFNbeta-1b, and for a mean of 21 months after terminating treatment with IFNbeta-1b. Post-treatment MRI activity was compared to baseline activity in these patients. Although contrast enhancing lesions (CEL) and the bulk white matter lesion load (BWMLL) on T2-weighted images eventually returned to baseline values, there was a refractory period of 6 - 10 months after terminating treatment, before baseline MRI activity was restored. Although the mechanism for a sustained effect of IFNbeta-1b is unclear at this time, these results have important implications for enrollment of such patients into new treatment protocols that rely on contrast enhancing lesion frequency as an outcome measure.

Distinct patterns of stimulus-inducible chemokine mRNA accumulation in human fetal astrocytes and microglia

Interferon-gamma-inducible 10 kd protein (IP-10) is an ELR (Glu-Leu-Arg)(-) alpha chemokine with known chemotactic effects on T cells and monocytes, as well as anti-viral, anti-angiogenic, and anti-tumor effects. Previous studies have demonstrated that in cultured rat astrocytes and microglia, stimulation with LPS or virus can induce the expression of IP-10. In this study, we determined the pattern of IP-10 gene induction in primary human microglia and astrocytes by cytokines and LPS using ribonuclease protection assay. The expression of IP-10 mRNA was compared with that of other alpha (IL-8) and beta chemokines. The results showed that in human microglia, IP-10 expression was induced equally potently by LPS, IFNbeta or IFNgamma. "Proinflammatory" cytokines IL-1beta or TNFalpha also induced small amounts of IP-10 mRNA. "Anti-inflammatory" cytokines IL-4, IL-10 and TGFbeta were ineffective in inducing IP-10 in microglia. In human astrocytes, induction of IP-10 mRNA by cytokines was similar to that in microglia. LPS, however, was ineffective in inducing IP-10 in human astrocytes. The monocyte chemoattractant beta-chemokine I-309 mRNA was induced in human astrocytes and microglia by IFNbeta or IFNgamma, or by LPS in microglia, showing a tight co-regulation with IP-10 mRNA expression. In contrast to the potent induction of IP-10 and I-309 by IFNs in human glia, the ELR(+) alpha chemokine IL-8 mRNA was induced by IL-1beta and TNFalpha, and to a lesser extent by IFNbeta in microglia. IFNbeta but not IFNgamma was effective in inducing the expression of beta chemokines MIP-1alpha and MIP-1beta in human microglia, with the levels of mRNA similar to those induced by IL-1beta or TNFalpha. Neither MIP-1alpha nor MIP-1beta mRNAs were induced by any stimulation in human astrocytes. The induction of RANTES mRNA in microglia by IFNbeta, IL-1beta or TNFalpha was variable, showing no to low level expression depending on the case, whereas LPS provided a consistent inducing signal. In astrocytes, only cytokine combinations (IFN + IL-1beta) effectively induced the RANTES mRNA. These results demonstrate that distinct sets of chemokine genes are induced in human glial cells by cytokines and interferons. These results may have wide implications for inflammatory, vascular and neoplastic diseases of the CNS.

IFN-beta modulates specific T cell responses in vitro but does not affect Experimental Autoimmune Encephalomyelitis in the SJL mouse

In this study, mouse recombinant IFN-beta was shown to favor PLP139-151-specific Th2 responses in vitro, by inhibiting IFN-gamma production and stimulating IL-4 and IL-10 production. IFN-beta (5000 U/day) failed to prevent the development or severity of EAE induced with PLP139-151. Whereas efficacy of IL-10 was found in the B. pertussis assisted but not in the pertussigen-assisted EAE model, both models appeared insensitive to IFN-beta. Also the combination of (suboptimal) IL-10 and IFN-beta appeared ineffective in inhibiting disease. However, the PLP139-151-specific IL-10 production by T cells from these mice appeared significantly more sensitive to the stimulatory effect of IFN-beta in vitro. It is concluded that despite its Th2 promoting effects, IFN-beta is not effective in inhibiting EAE in this study.

IFN-beta suppresses experimental autoimmune neuritis in Lewis rats by inhibiting the migration of inflammatory cells into peripheral nervous tissue

The putative prophylactic and therapeutic effect of interferon-beta (IFN-beta) on autoimmune inflammation of the peripheral nervous system was evaluated in experimental autoimmune neuritis (EAN), a well-known animal model of the human Guillain-Barré syndrome (GBS). We report that treatment of rats with 300,000 U of recombinant rat IFN-beta (rrIFN-beta) given every other day starting at the day of immunization prevented clinical signs of EAN. When treatment was started at the onset of disease development, the cytokine clearly ameliorated EAN. Both B- and T-cell responses towards peripheral myelin were suppressed by the IFN-beta, and immunohistochemical analyses revealed a strong decrease in the numbers of infiltrating CD4(+) T cells, macrophages, and other inflammatory cells as well as a significant reduction in MHC class II antigen expression and monocyte chemotactic protein-1 (MCP-1) production, which induces chemotaxis and chemokinesis of leukocytes from blood. It is concluded that the observed suppression of EAN by rrIFN-beta is associated with a decrease in the migration of inflammatory cells into peripheral nervous tissue.