Therapy with antibody against leukocyte integrin VLA-4 (CD49d) is effective and safe in virus-facilitated experimental allergic encephalomyelitis

Suppression of acute experimental allergic encephalomyelitis with a small molecule inhibitor of α4 integrin

Purpose: To determine the efficacy of a small molecule inhibitor of α4 integrin (CT301) at reversing the clinical, pathological and MR- detectable deficits associated with the acute phase of experimental allergic encephalomyelitis (EAE). Materials and methods: EAE was induced in 36 female Hartley guinea pigs, and the treatment period was from day 11 to day 17 post-immunization. Animals received either saline (n=12), anti-α4 integrin antibody (AN100226m; n=12) or CT301 (n=12). T2-weighted fast spin echo and T1-weighted pre- and post-contrast scans were performed at the beginning (day 11) and end (day 18) of the treatment period, and scored for cerebral inflammation and gadolinium enhancement. T1-weighted images were further analyzed to quantify this enhancement as a measure of blood-brain barrier integrity. Dissected CNS was evaluated for inflammation and demyelination. Results: CT301 successfully reversed two clinical indicators of disease over the course of the treatment period. These animals showed decreased T2-weighted abnormalities, as well as a reduction in gadolinium leakage on T1-weighted images. Meningeal and perivascular inflammation was decreased by anti-α4 integrin treatments. Conclusion: CT301 effectively reverses the clinical, pathological and MR-detectable deficits of acute EAE, and may therefore be a promising therapeutic agent in multiple sclerosis (MS).

Expression of a single ICAM-1 isoform on T cells is sufficient for development of experimental autoimmune encephalomyelitis

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in leukocyte trafficking, induction of cellular immune responses, and immunological synapse formation. As a member of the immunoglobulin superfamily of adhesion proteins, ICAM-1 is composed of repeating Ig-like domains, a transmembrane domain, and short cytoplasmic tail that participates in intracellular signaling events. At least seven ICAM-1 protein isoforms are generated by alternative splicing, however little is known regarding their immunobiology. We have previously shown using different lines of ICAM-1 mutant mice (Icam1(tm1Jcgr) and Icam1(tm1Bay) ) that expression of alternatively spliced ICAM-1 isoforms can significantly influence the disease course during the development of EAE. In this study, we show using a newly developed transgenic mouse (CD2-Icam1(D4del) /Icam1(null) ) that T-cell-specific expression of a single ICAM-1 isoform composed of Ig domains 1, 2, 3, and 5 can mediate the initiation and progression of EAE. Our results indicate that the ICAM-1 isoform lacking Ig domain 4 can drive pathogenesis in demyelinating disease and may be a novel therapeutic target for treating multiple sclerosis.

Multiparametric and semiquantitative scoring systems for the evaluation of mouse model histopathology--a systematic review

BACKGROUND

Histopathology has initially been and is still used to diagnose infectious, degenerative or neoplastic diseases in humans or animals. In addition to qualitative diagnoses semiquantitative scoring of a lesion`s magnitude on an ordinal scale is a commonly demanded task for histopathologists. Multiparametric, semiquantitative scoring systems for mouse models histopathology are a common approach to handle these questions and to include histopathologic information in biomedical research.

RESULTS

Inclusion criteria for scoring systems were a first description of a multiparametric, semiquantiative scoring systems which comprehensibly describe an approach to evaluate morphologic lesion. A comprehensive literature search using these criteria identified 153 originally designed semiquantitative scoring systems for the analysis of morphologic changes in mouse models covering almost all organs systems and a wide variety of disease models. Of these, colitis, experimental autoimmune encephalitis, lupus nephritis and collagen induced osteoarthritis colitis were the disease models with the largest number of different scoring systems. Closer analysis of the identified scoring systems revealed a lack of a rationale for the selection of the scoring parameters or a correlation between scoring parameter value and the magnitude of the clinical symptoms in most studies.

CONCLUSION

Although a decision for a particular scoring system is clearly dependent on the respective scientific question this review gives an overview on currently available systems and may therefore allow for a better choice for the respective project.

Virus-induced CD8+ T cells accelerate the onset of experimental autoimmune encephalomyelitis: implications for how viral infections might trigger multiple sclerosis exacerbations

Viral infections can exacerbate multiple sclerosis (MS) through poorly defined mechanisms. We developed an experimental system whereby infection with an asymptomatic neurotropic alphavirus caused a transient acceleration of experimental autoimmune encephalomyelitis (EAE) without altering the expansion or differentiation of autoreactive CD4+ T cells. Instead, this effect on the clinical course of EAE depended on CD8+ T cells that neither participate in viral clearance nor induce neuropathology in infected mice without EAE. Our system should be useful to further unravel how certain viral infections trigger MS exacerbations and to understand how CD8+ T cells can exert pathogenic effects within active demyelinating lesions.

Pharmacodynamic consequences of administration of VLA-4 antagonist CDP323 to multiple sclerosis subjects: a randomized, double-blind phase 1/2 study

Background

Lymphocyte inhibition by antagonism of α4 integrins is a validated therapeutic approach for relapsing multiple sclerosis (RMS).

Objective

Investigate the effect of CDP323, an oral α₄-integrin inhibitor, on lymphocyte biomarkers in RMS.

Methods

Seventy-one RMS subjects aged 18–65 years with Expanded Disability Status Scale scores ≤6.5 were randomized to 28-day treatment with CDP323 100 mg twice daily (bid), 500 mg bid, 1000 mg once daily (qd), 1000 mg bid, or placebo.

Results

Relative to placebo, all dosages of CDP323 significantly decreased the capacity of lymphocytes to bind vascular adhesion molecule-1 (VCAM-1) and the expression of α₄-integrin on VCAM-1–binding cells. All but the 100-mg bid dosage significantly increased total lymphocytes and naive B cells, memory B cells, and T cells in peripheral blood compared with placebo, and the dose-response relationship was shown to be linear. Marked increases were also observed in natural killer cells and hematopoietic progenitor cells, but only with the 500-mg bid and 1000-mg bid dosages. There were no significant changes in monocytes. The number of samples for regulator and inflammatory T cells was too small to draw any definitive conclusions.

Conclusions

CDP323 at daily doses of 1000 or 2000 mg induced significant increases in total lymphocyte count and suppressed VCAM-1 binding by reducing unbound very late antigen-4 expression on lymphocytes.

Trial Registration

ClinicalTrials.gov NCT00726648.

Anti-integrin therapy for multiple sclerosis

Integrins are the foremost family of cell adhesion molecules that regulate immune cell trafficking in health and diseases. Integrin alpha4 mediates organ-specific migration of immune cells to the inflamed brain, thereby playing the critical role in the pathogenesis of multiple sclerosis. Anti-alpha4 integrin therapy aiming to block infiltration of autoreactive lymphocytes to the inflamed brain has been validated in several clinical trials for the treatment of multiple sclerosis. This paper provides readers with an overview of the molecular and structural bases of integrin activation as well as rationale for using anti-alpha4 integrin therapy for multiple sclerosis and then chronicles the rise and fall of this treatment strategy using natalizumab, a humanized anti-alpha4 integrin.

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.

Experimental in vivo and in vitro models of multiple sclerosis: EAE and beyond

Although the primary cause of multiple sclerosis (MS) is unknown, the widely accepted view is that aberrant (auto)immune responses possibly arising following infection(s) are responsible for the destructive inflammatory demyelination and neurodegeneration in the central nervous system (CNS). This notion, and the limited access of human brain tissue early in the course of MS, has led to the development of autoimmune, viral and toxin-induced demyelination animal models as well as the development of human CNS cell and organotypic brain slice cultures in an attempt to understand events in MS. The autoimmune models, collectively known as experimental autoimmune encephalomyelitis (EAE), and viral models have shaped ideas of how environmental factors may trigger inflammation, demyelination and neurodegeneration in the CNS. Understandably, these models have also heavily influenced the development of therapies targeting the inflammatory aspect of MS. Demyelination and remyelination in the absence of overt inflammation are better studied in toxin-induced demyelination models using cuprizone and lysolecithin. The paradigm shift of MS as an autoimmune disease of myelin to a neurodegenerative disease has required more appropriate models reflecting the axonal and neuronal damage. Thus, secondary progressive EAE and spastic models have been crucial to develop neuroprotective approaches. In this review the current in vivo and in vitro experimental models to examine pathological mechanisms involved in inflammation, demyelination and neuronal degeneration, as well as remyelination and repair in MS are discussed. Since this knowledge is the basis for the development of new therapeutic approaches for MS, we particularly address whether the currently available models truly reflect the human disease, and discuss perspectives to further optimise and develop more suitable experimental models to study MS.

CNS elevation of vascular and not mucosal addressin cell adhesion molecules in patients with multiple sclerosis

The mucosal addressin cell adhesion molecule (MAdCAM) and vascular cell adhesion molecule (VCAM) appear to play roles in the recruitment of leukocytes to specialized endothelium lining the gastrointestinal tract. The purpose of this study was to clarify the role of MAdCAM and VCAM in the central nervous system by comparing protein expression in patients with multiple sclerosis (MS) and control subjects by immunohistochemistry. Specific antibodies to human VCAM and MAdCAM were used to confirm expression in control and MS nervous system specimens by immunohistochemistry. VCAM immunoreactivity was detected in endothelial cells, perivascular tissue, and in some cases, leukocytes within the meninges, gray, and white matter, of both controls and MS patients. VCAM immunoreactivity was maximal in a patient with acute active plaques, but of lower intensity and reduced distribution in controls and those with chronic active or inactive MS plaques. In contrast, MAdCAM immunoreactivity could not be detected in brain tissue from unaffected or MS patients. Taken together, these data support a role of VCAM, but not MAdCAM in the development of MS.

Clinical efficacy and benefit of natalizumab

Natalizumab is the first α4-integrin antagonist indicated for the treatment of relapsing multiple sclerosis (MS). Natalizumab has been shown to delay the accumulation of physical disability and reduce relapses. In two large, double-blind, randomized, placebo-controlled, phase 3 clinical trials, natalizumab was effective as a monotherapy as compared with placebo, and in combination with interferon β as compared with placebo and interferon β. Natalizumab in combination with glatiramer acetate was also effective in a phase 2 clinical trial when compared with placebo and glatiramer acetate. Natalizumab monotherapy achieved a 68% relative reduction in annualized relapse rate, and 42% and 54% reductions in disability progression sustained for 12 and 24 weeks, respectively. In a subset of patients with highly active disease, natalizumab proved more effective, decreasing relapse rates by 81% and progression of disability (sustained for 24 weeks) by 64%. Natalizumab-treated patients experienced significant improvements in quality of life, as measured by the Short Form-36, as well as a 35% reduction in risk of clinically significant vision loss. Recent analyses also have demonstrated the potential for natalizumab to induce a state of ‘no disease activity’ and actual improvement in physical disability. The purpose of this paper is to review evidence for the efficacy of natalizumab, and put its use in MS into perspective.

Restoring immune suppression in the multiple sclerosis brain

Multiple sclerosis is a very disabling inflammatory demyelinating disease of the brain of unknown etiology. Current therapies can reduce new lesion development and partially prevent clinical disease activity, but none can halt the progression, or cure the disease. We will review current therapeutic strategies, which are mostly discussed in literature in terms of their effective inhibition of T cells. However, we argue that many of these treatments also influence the myeloid compartment. Interestingly, recent evidence indicates that myelin phagocytosis by infiltrated macrophages and activated microglia is not just a hallmark of multiple sclerosis, but also a key determinant of lesion development and disease progression. We reason that severe side effects and/or insufficient effectiveness of current treatments necessitates the search for novel therapeutic targets, and postulate that these should aim at manipulation of the activation and phagocytic capacity of macrophages and microglia. We will discuss three candidate targets with high potential, namely the complement receptor 3, CD47-SIRPalpha interaction as well as CD200-CD200R interaction. Blocking the actions of complement receptor 3 could inhibit myelin phagocytosis, as well as migration of myeloid cells into the brain. CD47 and CD200 are known to inhibit macrophage/microglia activation through binding to their receptors SIRPalpha and CD200R, expressed on phagocytes. Triggering these receptors may thus dampen the inflammatory response. Our recent findings indicate that the CD200-CD200R interaction is the most specific and hence probably best-suited target to suppress excessive macrophage and microglia activation, and restore immune suppression in the brain of patients with multiple sclerosis.

Molecular mechanisms of T-cell receptor and costimulatory molecule ligation/blockade in autoimmune disease therapy

SUMMARY

Pro-inflammatory CD4(+) T-cell-mediated autoimmune diseases, such as multiple sclerosis and type 1 diabetes, are hypothesized to be initiated and maintained by activated antigen-presenting cells presenting self antigen to self-reactive interferon-gamma and interleukin-17-producing CD4(+) T-helper (Th) type 1/Th17 cells. To date, the majority of Food and Drug Administration-approved therapies for autoimmune disease primarily focus on the global inhibition of immune inflammatory activity. The goal of ongoing research in this field is to develop both therapies that inhibit/eliminate activated autoreactive cells as well as antigen-specific treatments, which allow for the directed blockade of the deleterious effects of self-reactive immune cell function. According to the two-signal hypothesis, activation of a naive antigen-specific CD4(+) T cell requires both stimulation of the T-cell receptor (TCR) (signal 1) and stimulation of costimulatory molecules (signal 2). There also exists a balance between pro-inflammatory and anti-inflammatory immune cell activity, which is regulated by the type and strength of the activating signal as well as the local cytokine milieu in which the naive CD4(+) T cell is activated. To this end, the majority of ongoing research is focused on the delivery of suboptimal TCR stimulation in the absence of costimulatory molecule stimulation, or potential blockade of stimulatory accessory molecules. Therefore, the signaling pathways involved in the induction of CD4(+) T-cell anergy, as apposed to activation, are topics of intense interest.

Modulation of experimental autoimmune encephalomyelitis by VLA-2 blockade

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Adhesion molecules play important roles in cell-cell and cell-extracellular matrix (ECM) interactions in inflammation. Blocking the interaction between inflammatory cells and vascular endothelia can prevent cell entry into tissues and harmful inflammatory responses, that is, autoimmunity, but could also limit immunosurveillance by anti-viral T cells in sites of infection or latency. Development of progressive multifocal leukoencephalopathy in patients treated with antibody against very late antigen (VLA)-4 prompted us to explore an alternative therapeutic approach. We used an antibody against the integrin alpha2, VLA-2, that interacts with ECM, not vascular endothelium. SJL/J mice were sensitized with myelin proteolipid protein (PLP)(139-151) peptide to induce experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Treatment of mice with VLA-2 antibody suppressed clinical signs and CNS inflammation of EAE, when antibody was given immediately after disease onset. In contrast, VLA-4 or VLA-2 antibody treatment of mice during the priming or remission phase of EAE had minor effects on the disease's clinical course. No differences were found in lymphoproliferative responses to PLP(139-151) among treatment groups. Data suggest that blocking cell-ECM interactions can be an alternative therapy for MS.

Region-specific regulation of inflammation and pathogenesis in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an animal model of multiple sclerosis and is characterized by an infiltrate of predominantly T cells and macrophages in the spinal cord and brain. In both the spinal cord and the cerebellum, Th1 cells direct inflammation to antigen-rich white matter tracts, and there is a TNFR1-dependent recruitment of CD11b(hi) cells in both regions. In the spinal cord, parenchymal invasion, demyelination and clinical symptoms are associated with TNFR1-dependant parenchymal induction (especially astrocytes) of VCAM-1 and CXCL2. None of these events occur in the cerebellum despite the fact that an inflammatory infiltrate accumulates in the perivascular space. Therefore regional specificity in astrocyte responses to inflammatory cytokines may regulate regional parenchymal infiltration and pathogenesis.

Reevaluation of P-selectin and alpha 4 integrin as targets for the treatment of experimental autoimmune encephalomyelitis

There has been a great deal of interest in adhesion molecules as targets for the treatment of multiple sclerosis and other inflammatory diseases. In this study, we systematically evaluate alpha(4) integrin and P-selectin as targets for therapy in murine models of multiple sclerosis-for the first time directly measuring the ability of their blockade to inhibit recruitment and relate this to clinical efficacy. Experimental autoimmune encephalomyelitis was induced in C57BL/6 or SJL/J mice and intravital microscopy was used to quantify leukocyte interactions within the CNS microvasculature. In both strains, pretreatment with blocking Abs to either alpha(4) integrin or P-selectin reduced firm adhesion to a similar extent, but did not block it completely. The combination of the Abs was more effective than either Ab alone, although the degree of improvement was more evident in SJL/J mice. Similarly, dual blockade was much more effective at preventing the subsequent accumulation of fluorescently labeled leukocytes in the tissue in both strains. Despite evidence of blockade of leukocyte recruitment mechanisms, no clinical benefit was observed with anti-adhesion molecule treatments or genetic deletion of P-selectin in the C57BL/6 model, or in a pertussis toxin-modified model in SJL/J mice. In contrast, Abs to alpha(4) integrin resulted in a significant delay in the onset of clinical signs of disease in the standard SJL/J model. Despite evidence of a similar ability to block firm adhesion, Abs to P-selectin had no effect. Importantly, combined blockade of both adhesion molecules resulted in significantly better clinical outcome than anti-alpha(4) integrin alone.

Spontaneous remyelination following prolonged inhibition of alpha4 integrin in chronic EAE

Inhibition of alpha(4)beta(1) integrin blocks immune cell influx into the CNS providing benefit to patients with multiple sclerosis and in animal model systems. We have used this mechanism to examine whether the presence of inflammatory cells suppresses spontaneous myelin repair in experimental autoimmune encephalomyelitis. We observed (1) 87% of plaques showed remyelination after 40 days of treatment; (2) myelin repair occurred in half of the total lesion area; (3) half of the animals regained motor function. There was no significant repair or gain of motor function in vehicle-treated animals. Therefore, prolonged inhibition of CNS inflammation, in the absence of targeted myelin repair, facilitates mechanisms of spontaneous remyelination.

Downregulation of VLA-4 on T cells as a marker of long term treatment response to interferon beta-1a in MS

We determined longitudinally the expression of a panel of adhesion molecules on T cells and soluble ICAM-1, VCAM-1 and tumor necrosis factor apoptosis inducing ligand (TRAIL) in serum during first year of the PRISMS Study with IFNbeta1a in MS. Clinical data and quantitative MRI data were available for 4 years. VLA-4 was down-regulated on T cells and VCAM-1 was up-regulated in serum during the first 3 to 6 months of therapy in patients with favorable long-term treatment response (EDSS progression </=1.0 in 4 years). Short disease duration and low EDSS were clinical pre-treatment characteristics related to good long-term response to therapy.

Macrophage brain infiltration in experimental autoimmune encephalomyelitis is not completely compromised by suppressed T-cell invasion: in vivo magnetic resonance imaging illustration in effective anti-VLA-4 antibody treatment

Large inflammatory infiltrates of T cells, macrophages and B cells in the central nervous system (CNS) contribute to the pathogenesis of multiple sclerosis (MS). The passage of T cells through the blood-brain barrier can be suppressed with antibodies directed against alpha-4 integrins (VLA-4) that mediate T-cell adherence. This treatment, in phase III of clinical trial evaluation, reduces lesion development in MS patients. In the ongoing inflammatory disease process the consequences of T-cell inhibitory anti-VLA-4 antibodies on inflammatory compounds are still poorly investigated. We show that anti-VLA-4 antibody treatment during the late preclinical phase of the acute experimental autoimmune encephalomyelitis (EAE) MS rat model interrupts T-cell egress out of the vascular compartment and suppresses clinical disease and histological alterations but macrophage recruitment in the CNS is not fully compromised. Among the treated EAE animals not developing disease, none presented foci of T-cell infiltration in CNS. However, in 75% of the treated EAE rats monocyte ingress in CNS was observed in vivo by magnetic resonance imaging with the ultrasmall superparamagnetic iron oxide contrast agent. Our data shed new light on the role of remaining macrophage brain infiltration in an induced but interrupted T-cell-mediated EAE disease process.

Expression of adhesion molecules on peripheral lymphocytes predicts future lesion development in MS

The expression of adhesion molecules (alpha4beta1-integrin, LFA-1, ICAM-1) on T cells, measured by flow cytometry, was compared in different subtypes of multiple sclerosis (MS) and related to future lesion development as seen as delta T1 and T2 lesion load per year on magnetic resonance imaging (MRI). LFA-1 and alpha4beta1-integrin showed higher expression on CD4 and CD8 T lymphocytes in the secondary progressive compared to the relapsing-remitting (CD4: p<0.01, p=ns, p<0.05; CD8: p<0.001, p<0.001, p<0.001, respectively) and primary progressive MS phase (CD4: p<0.001, p<0.01, p<0.05; CD8: p<0.01, p<0.01, p<0.001, respectively). The adhesion molecule expression of alpha4- (r=0.31; p<0.05) and beta1-integrin (r=0.38; p<0.01) on CD4+ cells and of LFA-1beta on both CD4+ and CD8+ (r=0.28, p<0.05) and r=0.29; p<0.05, respectively) cells was significantly related to increase in T2 lesion load. Our study provides further evidence for the involvement of integrins in lesion development, shown as T2 lesions on MRI in MS.

Antisense oligonucleotide blockade of alpha 4 integrin prevents and reverses clinical symptoms in murine experimental autoimmune encephalomyelitis

We investigated the use of an antisense oligonucleotide (ASO) specific for mRNA of the alpha chain (CD49d) of mouse VLA-4 to down-regulate VLA-4 expression and alter central nervous system (CNS) inflammation. ISIS 17044 potently and specifically reduced CD49d mRNA and protein in cell lines and in ex-vivo-treated primary mouse T cells. When administered prophylactically or therapeutically, ISIS 17044 reduced the incidence and severity of paralytic symptoms in a model of experimental autoimmune encephalomyelitis (EAE). This was accompanied by a significant decrease in the number of VLA-4+ cells, CD4(+) T cells, and macrophages present in spinal cord white matter of EAE mice. ISIS 17044 was found to accumulate in lymphoid tissue of mice, and oligonucleotide was also detected in endothelial cells and macrophage-like cells in the CNS, apparently due to disruption of the blood-brain barrier during EAE. These results demonstrate the potential utility of systemically administered antisense oligonucleotides for the treatment of central nervous system inflammation.

TNFR1-dependent VCAM-1 expression by astrocytes exposes the CNS to destructive inflammation

VCAM-1 is an adhesion molecule that is important to leukocyte movement across the blood-brain barrier and is involved in the formation of destructive CNS inflammatory lesions in experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS). We examined VCAM-1 expression in the CNS of animals with passively induced EAE and found abundant expression not only on the CNS endothelium but also on astrocytes. We show that tumor necrosis factor receptor-1 (TNFR1) signaling is required for VCAM-1 expression by astrocytes, not the vascular endothelium. In addition, we demonstrate that VCAM-1 expression by astrocytes is crucial for T cell entry into the CNS parenchyma and is required for manifestation of neurological disease.

Monoclonal antibody therapy in experimental allergic encephalomyelitis and multiple sclerosis

Experimental autoimmune encephalomyelitis (EAE) is a T-cell-mediated demyelinating disease of the central nervous system that has been used as an animal model for multiple sclerosis (MS). Based on the exciting results in EAE, a number of novel immunotherapies employing biotechnological products, rather than conventional immunosuppressants, are being developed for the treatment of MS. In this review, we delineate the rationale for monoclonal antibody (MAb) therapy in EAE and MS and summarize the various levels at which immune intervention was performed. For each approach, we discuss the role of MAbs at the level of lymphocyte and cytokine networks, chemokines, and adhesion molecules or their receptors.

Essential role of VLA-4/VCAM-1 pathway in the establishment of CD8+ T-cell-mediated Trypanosoma cruzi-elicited meningoencephalitis

Central nervous system (CNS) damage can occur during Trypanosoma cruzi infection, especially in immunosuppressed patients. The enhanced susceptibility of C3H/He mice to CD8-mediated acute meningoencephalitis is associated with higher up-regulation of vascular cell adhesion molecule-1 (VCAM-1) on CNS vascular endothelia than in the less susceptible C57BL/6. Further, in vitro adhesion of activated peripheral blood cells to CNS blood vessels was abrogated by anti-VLA-4 antibodies that also inhibited cell migration into the CNS of T. cruzi-infected mice. Lastly, the reactivation of meningoencephalitis in immunosuppressed chronically infected mice was associated with VCAM-1 up-regulation. Therefore, we hypothesize that VLA-4/VCAM-1 pathway plays a pivotal role in the establishment of T. cruzi-elicited encephalitis.

Adhesion molecules and matrix metalloproteinases in Multiple Sclerosis: effects induced by Interferon-beta

In Multiple Sclerosis (MS) pathology, early inflammation involves leukocyte migration across the blood-brain barrier (BBB) within the central nervous system. In this process, adhesion molecules (AMs), both membrane-bound and soluble-circulating forms, and matrix metalloproteinases (MMPs) certainly play a regulatory role. In MS, recombinant Interferon-beta (rIFNbeta) is effective in reducing gadolinium contrast-enhancing lesions on magnetic resonance imaging and this suggests that it may reduce BBB damage or even restore its integrity by different mechanisms that include interference with both AM and MMP pathways. This review will highlight the effects induced by rIFNbeta, both in vitro and in vivo, on cell-bound and soluble forms of AMs and on MMPs.

Prolonged reversal of chronic experimental allergic encephalomyelitis using a small molecule inhibitor of alpha4 integrin

CNS leukocytic invasion in experimental allergic encephalomyelitis (EAE) depends on alpha4beta1 integrin/vascular cell adhesion molecule-1 (VCAM-1) interactions. A small molecule inhibitor of alpha4beta1 integrin (CT301) was administered to guinea pigs in the chronic phase (>d40) of EAE for 10, 20, 30 or 40 days. CT301 elicited a rapid, significant improvement in the clinical and pathological scores that was maintained throughout the treatment period. A progressive loss of cells in the spinal cord of treated animals confirmed the resolution of inflammation associated with clinical recovery. Therefore, prolonged inhibition of alpha4beta1 integrin caused a sustained reversal of disease pathology in chronic EAE and may be similarly useful in MS.

VCAM-1-positive microglia target oligodendrocytes at the border of multiple sclerosis lesions

The distribution and lineage of vascular cell adhesion molecule-1 (VCAM-1)-positive cells was investigated in 43 lesions from the brain tissue of patients with multiple sclerosis (MS). Numerous VCAM-1-positive macrophages/microglia were detected at the edges of MS lesions. Quantitative analysis of 6 active, 7 chronic active, and 4 chronic inactive MS lesions identified most VCAM-1-positive cells at the actively demyelinating borders of active (102/mm3) and chronic active (29/mm3) lesions, but rarely in chronic inactive lesions (4/mm3). Further, approximately 17% of the VCAM-1-positive cells closely apposed or surrounded oligodendrocyte perikarya at the edges of active and chronic active lesions that were sites of ongoing demyelination. Endothelial cells were VCAM-1-negative in both lesion and non-lesion MS brain tissue. This report is the first to document direct microglial interaction with oligodendrocytes in MS.

Testicular-associated immune deviation: flushing of the testicular lymph sinusoids induces immunosuppression and inhibits formation of EAE in SJL mice

Injection of antigen into the testis has been previously proved to induce systemic tolerance in rats. Testicular-associated immune deviation (TAID) has thus far been induced and studied only in the rat and the present study was planned to study if TAID could be induced in mice as well. In addition, it was studied if TAID is organ-specific. Mouse spinal cord homogenate (MSCH), as well as phosphate-buffered saline (PBS), was injected into the testes of SJL and BALB/c male mice before the induction of experimental allergic encephalomyelitis into the animals. The control animals received MSCH intramuscularly into the hamstring muscles. The animals were followed and graded daily for symptoms attending the next 30 days. In the SJL strain, mice treated with an intratesticular (i.t.) MSCH injection prior to the induction of experimental autoimmune encephalomyelitis (EAE) had the shortest duration of symptoms and the longest time to the onset of the first symptoms. In addition, the mice injected i.t. with PBS had as mild symptoms as those injected with MSCH. There was a statistically significant difference, however, between the groups injected either with MSCH or PBS intratesticularly. In general, mice treated with an intramuscular injection of MSCH got sick first, and had the most severe symptoms for the longest duration of time. In the case of the BALB/c mice, there were no statistical differences between the groups investigated. It is concluded that TAID is a testis- and strain-specific phenomenon in the mouse, and not specific to the rat. In addition, i.t. injection of PBS is just as effective in creating tolerance against EAE as i.t. injection of MSCH in the SJL mice.

Beneficial effect of modified peptide inhibitor of alpha4 integrins on experimental allergic encephalomyelitis in Lewis rats

An important event in the pathogenesis of the autoimmune disease multiple sclerosis (MS) is the recruitment of lymphocytes and inflammatory macrophages to the central nervous system (CNS). Recruitment requires adhesive interactions between the leukocytes and the microvascular endothelium, perivascular cells, and astrocytes in the CNS parenchyma. Previous studies using an animal model of MS, experimental allergic encephalomyelitis (EAE), have shown the involvement of the alpha4 integrin VLA-4 (beta4beta1). In the present study, the effect of a modified peptide inhibitor of alpha4 integrins on the clinical course and leukocyte infiltration during EAE is investigated. EAE was either induced actively, by immunizing Lewis rats with whole guinea pig MBP, or passively, by transfer of an MBP-specific T cell line. Treatment with the inhibitor (CS1 ligand mimic) completely prevented both clinical signs and cellular infiltration in passively induced EAE. Peptide treatment of actively induced EAE, which has a more severe disease course than the transfer model, significantly reduced clinical signs although the recruitment of inflammatory cells and induction of MHC class II expression was not prevented. The alpha4 inhibitor did inhibit the adhesion of lymphocytes to primary astrocytes in vitro suggesting a role for astrocyte-leukocyte interactions in the pathogenesis of induced EAE. Astrocytes were found to express an extracellular matrix protein distinct from fibronectin, which shows immune cross-reactivity with the CS1 domain of fibronectin. Our results show that small-molecule inhibitors of alpha4 integrins act therapeutically in EAE possibly by interfering with cell adhesion events involved in this autoimmune disease.

Factors modifying the migration of lymphocytes across the blood-brain barrier

Characterising the factors that control the entry of leucocytes into tissue in response to inflammatory or microbial insult continues to generate considerable interest. Of all the tissues studied it is probably that of the CNS which is the most fascinating because of the specialised properties of its blood vessel walls, which constitute the blood-brain barrier (BBB). In health, very few leucocytes penetrate the BBB but in disorders such as MS the barrier becomes compromised with the result that there is an intense infiltration of the CNS by T lymphocytes whose subsequent activity appears to underlie the onset and progression of disease. The purpose of this article is to summarise and assess recent literature pertaining to how lymphocytes bind to cerebral endothelial cells, migrate across the blood vessel walls and enter the CNS parenchyma. Particular emphasis is devoted to the cellular and molecular aspects of these events and addressing the questions of whether certain subsets of circulating T lymphocytes are more favourably disposed than others to CNS infiltration and whether entry is dependent upon the initial expression of distinct groups of adhesion molecules and upon the generation of chemotactic factors. This article also focuses upon identifying the key stages of lymphocyte migration across the BBB and their susceptibility to antagonism by therapeutic agents. It is intended that the review will provide a useful source of information and offer additional insights into the mechanisms controlling lymphocyte passage across the BBB during pathological disturbance.

Reversal of experimental allergic encephalomyelitis with non-mitogenic, non-depleting anti-CD3 mAb therapy with a preferential effect on T(h)1 cells that is augmented by IL-4

This study examined whether therapy with a non-mitogenic, non-activating anti-CD3 mAb (G4.18) alone, or in combination with the T(h)2 cytokines, could inhibit induction or facilitate recovery from experimental allergic encephalomyelitis (EAE) in Lewis rats. G4.18, but not rIL-4, rIL-5 or anti-IL-4 mAb, reduced the severity and accelerated recovery from active EAE. A combination of rIL-4 with G4.18 was more effective than G4.18 alone. The infiltrate of CD4(+) and CD8(+) T cells, B cells, dendritic cells, and macrophages in the brain stem was less with combined G4.18 and IL-4 than G4.18 therapy or no treatment. Residual cells had preferential sparing of T(r)1 cytokines IL-5 and transforming growth factor-beta with loss of T(h)1 markers IL-2, IFN-gamma and IL-12Rbeta2, and the T(h)2 cytokine IL-4 as well as macrophage cytokines IL-10 and tumor necrosis factor-alpha. Lymph nodes draining the site of immunization had less mRNA for T(h)1 cytokines, but T(h)2 and T(r)1 cytokine expression was spared. Treatment with G4.18, rIL-4 or rIL-5 from the time of immunization had no effect on the course of active EAE. MRC OX-81, a mAb that blocks IL-4, delayed onset by 2 days, but had no effect on severity of active EAE. G4.18 also inhibited the ability of activated T cells from rats with active EAE to transfer passive EAE. This study demonstrated that T cell-mediated inflammation was rapidly reversed by a non-activating anti-CD3 mAb that blocked effector T(h)1 cells, and spared cells expressing T(h)2 and T(r)1 cytokines.

Prenatal exposure to ethanol alters the neuroimmune response to a central nervous system wound in the adult rat

We examined the long-term effects of in utero ethanol exposure on the expression of tumor necrosis factor-alpha (TNF-alpha), glial fibrillary acidic protein (GFAP), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and ED1 in the tissue at the site of a central nervous system (CNS) wound. Adult rats obtained from dams fed control diets or an ethanol diet were fed either control diets or an ethanol diet 5 days before and after infliction of a CNS wound. In pair-fed controls, the expression of TNF-alpha, GFAP, ICAM-1, VCAM-1, and ED1 immunoreactive proteins was increased in the tissue at the wound site when compared with that in nonlesioned tissues. In adult rats previously exposed to ethanol in utero and then fed a liquid diet before and after infliction of a CNS wound, however, expression of TNF-alpha, GFAP, and ICAM-1 was markedly decreased when compared with findings in pair-fed controls. In contrast, VCAM-1 levels and ED1 immunoreactive proteins were markedly increased when compared with findings for pair-fed controls. Furthermore, in adult rats exposed to ethanol in utero, re-exposure to ethanol before and after sustaining a CNS wound resulted in further decreases in TNF-alpha, GFAP, and ICAM-1 levels and marked increases in VCAM-1 levels and ED1 immunoreactive proteins. Results of these studies suggest to us that prenatal exposure to ethanol has a long-term immunoteratogenic effect in the CNS, resulting in altered responses of key components of the neuroimmune response, which could leave the animal immunocompromised as an adult.

Antibody to the alpha4 integrin decreases infarct size in transient focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

Inflammation, a process that involves neutrophils, lymphocytes, and monocytes, contributes to cerebral ischemic injury. Blockade of neutrophil adhesion to endothelium improves outcome after experimental stroke. In this study we sought to assess the contribution of lymphocytes and monocytes to ischemic brain injury.

METHODS

Male Lewis rats underwent 3 hours of middle cerebral artery occlusion followed by 45 hours of reperfusion. Two hours after the onset of ischemia, one group of animals received an intraperitoneal injection of antibodies to the alpha(4) integrin (n=16); another group was injected with an isotype control antibody (n=11). Neurological examination, body temperature, and body weight were assessed at different time points after stroke. Animals were killed 48 hours after the onset of ischemia for determination of infarct volume and leukocyte counts.

RESULTS

There were no significant differences in body temperature or weight at any time. Neurological scores (deficits) were significantly less in animals treated with anti-alpha(4) antibodies at 24 (2.0+/-1.2 versus 3. 0+/-0.4; P:=0.006) and 48 (2.0+/-1.2 versus 3.0+/-0.8; P:=0.011) hours after ischemia. Peripheral blood leukocyte counts were significantly higher in anti-alpha(4)-treated animals (6.8+/-2.2 x 10(9) versus 2.9+/-1.9 x 10(9); P:=0.001) and revealed a lymphocyte/monocyte predominance (86.0+/-16.2% versus 71.0+/-15.6%; P:=0.008). Infarct volume was significantly less in animals treated with antibodies to alpha(4) (120.1+/-51.21 versus 173.7+/-42.29 mm(3); P:=0.012).

CONCLUSIONS

These data support a role for lymphocytes and monocytes in cerebral ischemic injury and show that blockade of alpha(4), even when instituted after the onset of ischemia, can improve neurological outcome and decrease infarct volume.

CD4(+)CD45RO(+)CD49d(high) cells are involved in the pathogenesis of relapsing-remitting multiple sclerosis

In the animal model of multiple sclerosis, experimental autoimmune encephalomyelitis, encephalitogenic T cells differ from the non-encephalitogenic ones in their expression of CD49d. The disease-inducing CD49d(high) and not the CD49d(low) cells enter the brain parenchyma. In this context, we characterized CD4(+)(CD45RO(+))CD49d(high) cells in relapsing-remitting multiple sclerosis (RR-MS) patients. These cells, showing characteristics of activated cells able to produce pro-inflammatory cytokines, were found to be increased in peripheral blood during relapses and present in high numbers in cerebrospinal fluid. These results suggest that the CD4(+)CD45RO(+)CD49d(high) subpopulation in RR-MS patients includes autoreactive cells and may be target for immunotherapy.

Inhibition of monocyte/macrophage migration to a spinal cord injury site by an antibody to the integrin alphaD: a potential new anti-inflammatory treatment

The inflammatory response that ensues during the initial 48 to 72 h after spinal cord injury causes considerable secondary damage to neurons and glia. Infiltration of proinflammatory-activated neutrophils and monocytes/macrophages into the cord contributes to spinal cord injury-associated secondary damage. beta2 integrins play an essential role in leukocyte trafficking and activation and arbitrate cell-cell interactions during inflammation. The beta2 integrin, alphaDbeta2, is expressed on monocytes/macrophages and neutrophils and binds to vascular adhesion molecule-1 (VCAM-1). The increased expression of VCAM-1 during central nervous system (CNS) inflammation likely contributes to leukocyte extravasation into the CNS. Accordingly, blocking the interaction between alphaDbeta2 and VCAM-1 may attenuate the inflammatory response at the SCI site. We investigated whether the administration of monoclonal antibodies (mAbs) specific for the rat alphaD subunit would reduce the inflammatory response after a spinal cord transection injury in rats. At a 1 mg/kg dose two of three anti-alphaD mAbs caused a significant ( approximately 65%) reduction in the number of macrophages at the injury site and one anti-alphaD mAb led to a approximately 43% reduction in the number of neutrophils at the SCI site. Thus, our results support the concept that the alphaDbeta2 integrins play an important role in the trafficking of leukocytes to a site of central nervous system inflammation. This study also offers preliminary evidence that anti-alphaD mAbs can reduce the extravasation of macrophages and, to a lesser extent, neutrophils, to the SCI site.

Distinct roles for matrix metalloproteinase-2 and alpha4 integrin in autoimmune T cell extravasation and residency in brain parenchyma during experimental autoimmune encephalomyelitis

Expression of alpha4 integrin by auto-reactive T cells is critical for their ability to induce EAE, an autoimmune disease of the central nervous system in mice, used as a model to study human multiple sclerosis. Having previously identified one role for alpha4 integrin in adhesion-mediated induction of matrix metalloproteinase-2 (MMP-2), an enzyme that degrades the subendothelial basement membrane matrix, we investigated independent roles for MMP-2 and alpha4 integrin during EAE. The data suggest that expression of alpha4 integrin by auto-reactive T cells is important not only in mediating MMP-2 induction to facilitate entry into the CNS, but also plays a role in maintaining residency within the CNS.

Treatment of experimental autoimmune encephalomyelitis with antisense oligonucleotides against the low affinity neurotrophin receptor

Upregulated expression of the low-affinity neurotrophin receptor (p75) in the central nervous system (CNS) during experimental autoimmune encephalomyelitis (EAE) has recently been demonstrated. To investigate whether p75 plays a role in disease pathogenesis, we adopted a gene therapy approach, utilizing antisense oligonucleotides to downregulate p75 expression during EAE. Phosphorothioate antisense oligonucleotides (AS), nonsense oligonucleotides (NS) or phosphate buffered saline (PBS) were injected daily for 18 days after immunization of SJL/J (H-2s)-mice with myelin proteolipid protein (PLP) peptide 139-151. In the AS group, there was a statistically significant reduction in both the mean maximal disease score (1.85 in the AS, 2.94 in the NS and 2.75 in the PBS-groups, respectively, P < 0.025) and in the cumulative disease incidence ( approximately 60% in the AS group and approximately 90% in the control groups). Histological and immunohistochemical analysis showed reduced inflammation and demyelination, as well as reduced p75 expression at the blood-brain barrier (BBB) in the AS-treated mice in comparison with both control groups. There was no difference, however, in p75 expression on neural cells within the CNS between the three groups of mice. We conclude that p75 could play a proactive role in the pathogenesis of EAE and may exert its effect at the level of the BBB.

Immunological profile of patients with primary progressive multiple sclerosis. Expression of adhesion molecules

Adhesion molecules are important in the trafficking of peripheral leucocytes into the central nervous system, a major event in the pathogenesis of multiple sclerosis, which is an inflammatory and demyelinating disease. The latest MRI evidence supports clinical divergence between forms of multiple sclerosis with relapses and the primary progressive form without relapses, which shows fewer and smaller inflammatory lesions. With the aim of elucidating whether different pathogenic mechanisms are involved in primary progressive multiple sclerosis, we compared membrane expression of the adhesion molecules ICAM-1 (CD54), LFA-1alpha (CD11a), VLA-4 [alpha(4)/beta(1) integrin (CD49d/CD29)], L-selectin (CD62L) and ICAM-3 (CD50) in peripheral blood and the serum-soluble forms ICAM-1, L-selectin, VCAM-1 and ICAM-3 in 89 patients (39 with the primary progressive form, 25 with the secondary progressive form and 25 with the relapsing-remitting form) and 38 healthy controls. We found a significant decrease in leucocyte surface expression of most of the adhesion molecules tested and an increase in soluble ICAM-1 and L-selectin levels in secondary progressive and relapsing-remitting multiple sclerosis compared with primary progressive multiple sclerosis, which gave results similar to those in controls. These results, which are supported by MRI evidence, show that trafficking of autoreactive leucocytes through the blood-brain barrier is crucial to the pathogenesis of secondary progressive and relapsing-remitting forms of multiple sclerosis, whereas other mechanisms leading to progressive axonal damage would account for primary progressive forms of the disease.

Molecular pathogenesis of multiple sclerosis

Multiple sclerosis (MS) is best understood as an inflammatory disease of the central nervous system (CNS) white matter characterized by demyelination, focal T cell and macrophage infiltrates, axonal injury and loss of neurological function. Our current understanding invokes proinflammatory cells and mediators that may be triggered by environmental factors to mediate disease in a genetically susceptible host. Five major themes which have been associated with the pathogenesis of MS lesions will be discussed: (1) The differential activation states of myelin-reactive T cells from MS patients vs. normal individuals, (2) the selective expression of chemokines, adhesion molecules and matrix metalloproteinases, (3) the proposed roles of the B7 costimulatory pathway, (4) the proinflammatory cytokines and (5) the role of molecular mimicry.

Adhesion molecule expression and regulation on cells of the central nervous system

Cellular adhesion molecules were initially defined as cell surface structures mediating cell-cell and cell-extracellular matrix (ECM) interactions. Adhesion molecules involved in immune responses have been classified into three families according to their structure: selectins, immunoglobulin (Ig) superfamily, and integrins. It has been well documented that adhesion molecules of these family members (E-selectin, ICAM-1, and VCAM-1) are expressed on brain microvessel endothelial cells in active lesions of multiple sclerosis (MS) brain. In addition, accumulating data show that glial cells can express some of these adhesion molecules upon activation: astrocytes can express ICAM-1, VCAM-1, and E-selectin, and microglia express ICAM-1 and VCAM-1. In vitro studies show that these adhesion molecules are actively regulated by several cytokines which have relevance to MS or experimental autoimmune encephalomyelitis (EAE). In addition, soluble forms of adhesion molecules have been found in the serum and cerebrospinal fluid (CSF) of MS patients, and may be useful diagnostically. Experimental therapy of EAE using antibodies against several adhesion molecules clearly shows that adhesion molecules are critical for the pathogenesis of EAE. Thus far, the function of adhesion molecule expression on brain endothelial and glial cells has not been clearly elucidated. Studies on the possible role of adhesion molecules on brain endothelial and glial cells will be helpful in understanding their involvement in immune responses in the central nervous system (CNS).

Contrasting effects of anti-adhesion molecule therapy in experimental allergic encephalomyelitis and Theiler's murine encephalomyelitis

An augmentation of experimental allergic encephalomyelitis (EAE) was observed when monoclonal antibody (mAb) to intercellular adhesion molecule 1 (ICAM-1) was administered after adoptive transfer. Clinical disease was more severe in the ICAM-1 specific mAb-treated EAE mice and included prominent ataxia compared to the PBS-treated controls or Theiler's murine encephalomyelitis virus (TMEV) infected mice treated with ICAM-1 specific mAb. Neuropathologic evaluation demonstrated a distinctly different distribution of lesions in the anti-ICAM-1-treated EAE mice which featured prominent demyelination and inflammation in the cerebellum, brainstem and cerebrum. These structures were minimally involved in the control mice and mAb treatment did not alter the neuropathology in TMEV-infected mice. These results indicate that anti-ICAM-1 can alter trafficking of lymphocytes and mononuclear cells in EAE but not TMEV-induced demyelinating disease.

Platelet activating factor is elevated in cerebral spinal fluid and plasma of patients with relapsing-remitting multiple sclerosis

Platelet-activating factor (PAF) is a phospholipid mediator of inflammation with a wide range of biological activities, including the alteration of barrier function of endothelium. A biological assay combined with high pressure liquid chromatography-tandem mass spectrometry showed that plasma and cerebral spinal fluid (CSF) PAF levels in 20 patients with relapsing/remitting or secondary progressive multiple sclerosis (MS) studied by magnetic resonance imaging (MRI) were significantly higher than in healthy controls (plasma: 3.29+/-4.52 vs. 0.48+/-0.36 ng/ml, p < 0.002; CSF: 4.95+/-6.22 ng/ml vs. 0.01+/-0.04 ng/ml, p < 0.0001). Values were also significantly higher in relapsing/remitting than in secondary progressive (plasma: 5.10+/-4.97 vs. 0.52+/-0.85 ng/ml, p < 0.005; CSF: 8.59+/-6.39 vs. 0.55+/-0.68 ng/ml, p < 0.002). It was also found that both plasma (R2: 0.65) and CSF (R2:0.72) levels were correlated with the MRI number of gadolinium enhancing lesions, which are markers of blood-brain barrier (BBB) injury, whereas their peaks were not correlated with the MRI number of white matter lesions, nor with the expanded disability status score (EDSS) according to Kurtze [Kurtze, J.F., 1983. Rating neurological impairment in multiple sclerosis: an expanded disability scale (EDSS). Neurology 33, 1444-1452]. Both plasma and CSF in patients with relapsing/remitting MS and marked gadolinium enhancement contained the two major molecular species of PAF: 1-0-hexadecyl- (C16:O) and 1-0-octadecyl-sn-glycero-3-phosphocholine (C18:O). The ratio of the two molecular species was different in the two biological fluids, being PAF C18:0 more abundant in CSF and PAF C16:0 in plasma, indicating a different cellular origin of PAF or different enzymatic processing. These findings suggest that PAF is a significant mediator of BBB injury in the early stages of MS, rather than a marker of its progression and severity.

Neutrophils secreting tumor necrosis factor alpha infiltrate the central nervous system of BALB/c mice with experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) can be induced in resistant BALB/c mice by ultrasound-formed adjuvant emulsion. In contrast to susceptible mouse strains large numbers of neutrophils secreting TNF-alpha occupied the central nervous system (CNS) of BALB/c mice with severe EAE, whereas only small numbers of macrophages and CD4+ T-cells could be detected. CNS infiltration was preceded with activation of microglial cells. Ultrasound formed adjuvant induced early IFN-gamma expression in popliteal lymph nodes of BALB/c mice, whereas conventional adjuvant induced delayed IFN-gamma production. Although the clinical outcome of EAE was similar to that seen in susceptible mice, the pathogenesis was distinct having possible implications on the different forms seen in multiple sclerosis.

Transforming growth factor-beta inhibition of cytokine-induced vascular cell adhesion molecule-1 expression in human astrocytes

Leukocyte transmigration across the blood-brain barrier (BBB) is a cardinal feature of central nervous system (CNS) inflammation. Astrocytes form an integral part, both structurally and functionally, of the BBB. Vascular cell adhesion molecule-1 (VCAM-1), a member of the immunoglobulin gene superfamily, is involved in extravasation into inflamed tissues and activation of T-lymphocytes. In this study, we investigated the role of TGF-beta, an immunosuppressive cytokine, in regulating cytokine-induced VCAM-1 expression in astrocytes. Human astroglioma cell lines and primary human fetal astrocytes were examined for VCAM-1 gene expression after treatment with proinflammatory cytokines (TNF-alpha, IL-1beta, IFN-gamma) in the absence or presence of TGF-beta. Astroglioma cell lines as well as primary human fetal astrocytes expressed low levels of VCAM-1 constitutively, and the proinflammatory cytokines induced marked increases in VCAM-1 expression, particularly TNF-alpha and IL-1beta. The inclusion of TGF-beta1 or TGF-beta2 with the proinflammatory cytokines inhibited VCAM-1 gene expression to varying degrees (33-93%) in all the astroglioma cell lines and primary fetal cells. These results indicate that TGF-beta is an important regulator of cytokine induced VCAM-1 expression on astrocytes and may prove useful clinically in controlling CNS inflammation.