The efficacy of cyclosporin A,FK-506 and Prednisolone to modify the adoptive transfer of Experimental Allergic Encephalomyelitis (EAE)

Thein vitro potency of the immunosuppressants Cyclosporin A (CsA), FK-506 and Prednisolone was assessed using the adoptive transfer model of EAE in the Lewis rat. Co-culture of encephalitogen-sensitised splenic leukocytes with Prednisolone did not inhibit the transfer of disease to naive histocompatible recipients despite significant suppression of neuroantigen-stimulated leukocyte proliferation by the drug. The addition of CsA (100 nM) to cultures inhibited the induction of adoptive EAE but a lower dose of the agent (10 nM) did not prevent the development of clinico-histopathological signs of disease. FK-506 (1 nM) was 100 times more effective than CsA at suppressing adoptive EAE thus emphasising the usefulness of the model in determining the relative efficacy of compounds to modify cell-dependent autoimmune disease.     

Disease modifying activity of 15-deoxyspergualin on acute and chronic relapsing experimental allergic encephalomyelitis as models of multiple sclerosis (MS)

Due to its immunosuppressive mode of action we examined the therapeutic effects of 15-Deoxyspergualin (15-DOS) in the two models of acute and chronic relapsing experimental allergic encephalomyelitis (EAE) in Lewis rats. Treatment of myelin basic protein (MBP) immunized rats with 15-DOS was most effective in delaying and reducing the onset of clinical symptoms, and mortality was prevented in acute EAE. Similarly, in the chronic relapsing disease, inhibition of pathological signs and prevention of relapses were observed, even when 15-DOS treatment was started after the appearance of the first clinical symptoms. The drug was also effective in preventing the passive adoptive transfer of the disease to naive Lewis rats, and when encephalitogenic spleen cells from diseased animals were incubatedin vitro with 15-DOS their neuritogenicity was dose-dependent abrogated. All these results confirm that 15-DOS is a powerful immunosuppressant for the therapy of human multiple sclerosis (MS).

     

Lumican negatively controls the pathogenicity of murine encephalitic TH17 cells

TH17 cells play an essential role in the development of both human multiple sclerosis and animal experimental autoimmune encephalomyelitis (EAE). Nevertheless, it is not well understood how the pathogenicity of TH17 cells is controlled in the autoimmune neuroinflammation. In vitro, we found Lumican (Lum), an extracellular matrix (ECM) protein, is selectively expressed by TH17 cells among tested murine TH subsets. Lum deficiency leads to earlier onset and enhanced severity of EAE. This enhanced disease in Lum‐deficient mice is associated with increased production of IL‐17 and IL‐21 and decreased TH17 cell apoptosis. Dysregulation in cytokine production appears to be specific to TH17 cells as TH1 and TH2 cell polarization and/or cytokine production were unaltered. Furthermore, adoptive transfer of myelin oligodendrocyte glycoprotein specific TH17 cells derived from Lum‐deficient mice led to earlier onset and increased severity of disease compared to controls highlighting a TH17‐cell‐intrinsic effect of Lum. Taken together, our results suggest that Lum negatively regulates encephalitic TH17 cells, implicating a potential therapeutic pathway in TH17 cell mediated autoimmune and inflammatory diseases.     

Regulation of IL-10 and IL-17 mediated experimental autoimmune encephalomyelitis by S-nitrosoglutathione

In this study, we investigated IL-10 and IL-17 specific immunomodulatory potential of S-nitrosoglutathione (GSNO), a physiological nitric oxide carrier molecule, in experimental autoimmune encephalomyelitis (EAE). In active EAE model, GSNO treatment attenuated EAE severity and splenic CD4⁺ T cells isolated from these mice exhibited decreased IL-17 expression without affecting the IFN-γ expression compared to the cells from untreated EAE mice. Similarly, adoptive transfer of these cells to nave mice resulted in reduction in IL-17 expression in the spinal cords of recipient mice with milder EAE severity. CD4⁺ T cells isolated from GSNO treated EAE mice, as compared to untreated EAE mice, still expressed lower levels of IL-17 under T_H17 skewing conditions, but expressed similar levels of IFN-γ under T_H1 skewing condition. Interestingly, under both T_H17 and T_H1 skewing condition, CD4⁺ T cells isolated from GSNO treated EAE mice, as compared to untreated EAE mice, expressed higher levels of IL-10 and adoptive transfer of these T_H17 and T_H1 skewed cells seemingly exhibited milder EAE disease. In addition, adoptive transfer of CD4⁺ T cells from GSNO treated EAE mice to active EAE mice also ameliorated EAE disease with induction of spinal cord expression of IL-10 and reduction in of IL-17, thus suggesting the participation of IL-10 mechanism in GSNO mediated immunomodulation. GSNO treatment of mice passively immunized with CD4⁺ T cells either from GSNO treated EAE mice or untreated mice further ameliorated EAE disease, supporting efficacy of GSNO for prophylaxis and therapy in EAE. Overall, these data document a modulatory role of GSNO in IL-17/IL-10 axis of EAE and other autoimmune diseases.     

Suppression of experimental autoimmune encephalomyelitis in Lewis rats by antibodies against CD2

The immunotherapeutic potential of three anti-rat CD2 monoclonal antibodies (mAb) (OX34, OX54, OX55) and the combination of OX54 with OX55 was tested in Lewis rat experimental autoimmune encephalomyelitis (EAE). In actively induced EAE, a single injection of OX34 2 days before immunization with myelin basic protein (MBP) in complete Freund's adjuvant (CFA) completely prevented or greatly attenuated EAE in all animals. Injection of OX54 acted moderately suppressive while OX55 or OX54/55 did not affect disease severity. Abrogation of EAE by OX34 was not restricted to its application before immunization. Therapeutic administration of all three mAb and the Ab combination from onset of first clinical signs efficiently blocked progression of disease and prevented all animals from developing hind limb paresis. In adoptive transfer EAE induced with in vitro activated cells of an encephalitogenic T helper line, clinical and histological signs were completely prevented by injection of OX34 on the day of cell transfer and 4 days later, underlining the strong impact of anti-CD2 mAb on the effector phase of disease. Immunocytofluorometric analysis of peripheral blood lymphocytes after a single Ab injection demonstrated that all mAb induced a variable degree of transient reduction in T cell numbers and modulation of CD2 antigens. In contrast to the other mAb, OX34 persisted on lymphocytes for at least 11 days, which may explain its unique suppressive effect on EAE after a single injection before immunization. The assumption that prophylactic administration of OX34 also inhibits MBP-induced EAE, due to persistence into the effector phase, was substantiated by the finding that none of the mAb prevented generation of an antigen-specific cellular response in MBP/CFA-immunized animals. Since none of the Ab induced T cell unresponsiveness or inhibited T cell activation by antigen- or Ab-mediated stimulation of the T cell receptor, we suggest that their marked action on the effector phase of EAE may rely on inhibition of T cell infiltration into the central nervous system. The demonstrated efficacy of these anti-CD2 mAb in EAE suggests a potential therapeutic role that may be equal to that of anti-CD4 or anti-T cell receptor Ab.     

Experimental autoimmune encephalomyelitis in IL-4-deficient mice

Experimental autoimmune encephalomyelitis (EAE) in an inflammatory demyelinating disease which usually follows a monophasic course. Autoreactive Th1 CD4+ T cells are responsible for the lesions, whereas autoreactive Th2 CD4+ T cells can, upon adoptive transfer, suppress the disease process. However, the role of IL-4 and Th2 cells in the spontaneous remission of EAE and in the prevention of relapses is not known. We have addressed these issues using IL-4-deficient mice in which the differentiation of Th2 CD4+ T cells is severely compromised. The clinical course of actively induced EAE was compared in IL-4+/+, IL- 4+ /- and IL-4-/- mice on the PL/J genetic background. No significant differences were noted between groups for the frequency, severity and duration of EAE, and the frequency of relapses. Our results indicate that IL-4, despite its well-documented regulatory role in EAE, is not necessary for the spontaneous remission of disease or for the prevention of relapses. Therefore, in the absence of IL-4, overlapping or compensatory immunoregulatory mechanisms can restrict an inflammatory response within the central nervous system.      

Experimental allergic encephalomyelitis (EAE) in mice lacking CD4+ T cells

Like most experimental autoimmune disease experimental allergic encephalomyelitis (EAE) has been shown to be mediated by CD4⁺ helper T cells. In vivo antibody blocking studies with anti-CD4 and adoptive transfer of activated CD4⁺ T cells indicate the importance of CD4⁺ cells in disease induction. Fourth backcross generation mutant CD4—/— PL/J mice were immunized with myelin basic protein. Despite the lack CD4⁺ T cells some of these mice developed EAE, albeit, at a considerably reduced frequency and with variable severity. Furthermore, antigen-specific T cell proliferation can be demonstrated, indicating some residual helper activity that is major histocompatibility complex class II restricted. This demonstrates that, although the CD4⁺ T cell is the prime effector cell in EAE, in mice developmentally lacking in CD4, the expanded double-negative T cells may subserve helper and effector functions.     

Age Dependence of Clinical and Pathological Manifestations of Autoimmune Demyelination : Implications for Multiple Sclerosis

A prominent feature of the clinical spectrum of multiple sclerosis (MS) is its high incidence of onset in the third decade of life and the relative rarity of clinical manifestations during childhood and adolescence, features suggestive of age-related restriction of clinical expression. Experimental allergic encephalomyelitis (EAE), a model of central nervous system (CNS) autoimmune demyelination with many similarities to MS, has a uniform rapid onset and a high incidence of clinical and pathological disease in adult (mature) animals. Like MS, EAE is most commonly seen and studied in female adults. In this study, age-related resistance to clinical EAE has been examined with the adoptive transfer model of EAE in SJL mice that received myelin basic protein-sensitized cells from animals 10 days (sucklings) to 12 weeks (young adults) of age. A variable delay before expression of clinical EAE was observed between the different age groups. The preclinical period was longest in the younger (<14 days of age) animals, and shortest in animals 6 to 8 weeks old at time of transfer. Young animals initially resistant to EAE eventually expressed well-developed clinical signs by 6 to 7 weeks of age. This was followed by a remitting, relapsing clinical course. For each age at time of sensitization, increased susceptibility of females compared to males was observed. Examination of the CNS of younger animal groups during the preclinical period showed lesions of acute EAE. Older age groups developed onset of signs coincident with acute CNS lesions. This age-related resistance to clinical EAE in developing mice is reminiscent of an age-related characteristic of MS previously difficult to study in vivo. The associated subclinical CNS pathology and age-related immune functions found in young animals may be relevant to the increasing clinical expression of MS with maturation, and may allow study of factors associated with the known occasional poor correlation of CNS inflammation and demyelination and clinical changes in this disease.     

CCL22 regulates experimental autoimmune encephalomyelitis by controlling inflammatory macrophage accumulation and effector function

EAE is a demyelinating disease of the CNS and serves as a mouse model of MS. Expression of CCL22 in the draining LNs and spinal cord correlated with the onset of clinical EAE development and remained elevated. Administration of anti-CCL22 at the time of autoantigen immunization delayed the initiation of clinical disease and dampened the severity of peak initial disease and relapses. Reduced EAE severity correlated with the reduction of pathology and leukocytes in the CNS, particularly, activated CD11b+Ly6C(hi) macrophages. There were no differences in effector T cell-proliferative responses or effector T cell IFN-γ or IL-17 responses. However, treatment at the onset of disease did not reduce disease progression. Treatment of adoptive T cell transfer recipient mice with anti-CCL22 resulted in decreased clinical disease development accompanied by a decrease in CNS accumulation of CD11b+Ly6C(hi) macrophages. Neutralization of CCL22 resulted in a macrophage population whose effector cytokine expression consisted of decreased TNF and increased IL-10, a phenotype more consistent with M2 macrophages. This was corroborated by in vitro cultures of macrophages with CCL22. These results suggest that CCL22 functions to regulate development of EAE through macrophage chemoattraction and effector function.     

Disease modifying activity of 15-deoxyspergualin on acute and chronic relapsing experimental allergic encephalomyelitis as models of multiple sclerosis (MS)

Due to its immunosuppressive mode of action we examined the therapeutic effects of 15-Deoxyspergualin (15-DOS) in the two models of acute and chronic relapsing experimental allergic encephalomyelitis (EAE) in Lewis rats. Treatment of myelin basic protein (MBP) immunized rats with 15-DOS was most effective in delaying and reducing the onset of clinical symptoms, and mortality was prevented in acute EAE. Similarly, in the chronic relapsing disease, inhibition of pathological signs and prevention of relapses were observed, even when 15-DOS treatment was started after the appearance of the first clinical symptoms. The drug was also effective in preventing the passive adoptive transfer of the disease to naive Lewis rats, and when encephalitogenic spleen cells from diseased animals were incubatedin vitro with 15-DOS their neuritogenicity was dose-dependent abrogated. All these results confirm that 15-DOS is a powerful immunosuppressant for the therapy of human multiple sclerosis (MS).Joint summary of 3 presentations given at Inflammation '93.     

MOG35–55 i.v suppresses experimental autoimmune encephalomyelitis partially through modulation of Th17 and JAK/STAT pathways

Intravenous (i.v.) administration of encephalitogenic peptide can effectively prevent experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis; however, the underlying cellular and molecular mechanisms are not fully understood. In this study, we induced i.v. tolerance to EAE by administration of MOG_35–55 peptide and determined the effect of this approach on intracellular signaling pathways of the IL‐23/IL‐17 system, which is essential for the pathogenesis of MS/EAE. In tolerized mice, phosphorylation of JAK/STAT‐1, ‐4, ERK1/2 and NF‐κBp65 were significantly reduced in splenocytes and the central nervous system. MOG i.v. treatment led to significantly lower production of IL‐17, and administration of exogenous IL‐17 slightly broke immune tolerance, which was associated with reduced activation of STAT4 and NF‐κB. Suppressed phosphorylation of these pathway molecules was primarily evident in CD11b⁺ and small numbers of CD4⁺, CD8⁺ and CD11c⁺ cells. More importantly, adoptive transfer of CD11b⁺ splenocytes of tolerized mice effectively delayed onset and reduced clinical severity of actively induced EAE. This study correlates MOG i.v. tolerance with modulation of Jak/STAT signaling pathways and investigates novel therapeutic avenues for the treatment of EAE/MS.     

Expiratory muscle fatigue impairs exercise performance

High-intensity, exhaustive exercise may lead to inspiratory as well as expiratory muscle fatigue (EMF). Induction of inspiratory muscle fatigue (IMF) before exercise has been shown to impair subsequent exercise performance. The purpose of the present study was to determine whether induction of EMF also affects subsequent exercise performance. Twelve healthy young men performed five 12-min running tests on a 400-m track on separate days: a preliminary trial, two trials after induction of EMF, and two trials without prior muscle fatigue. Tests with and without prior EMF were performed in an alternate order, randomly starting with either type. EMF was defined as a ≥20% drop in maximal expiratory mouth pressure achieved during expiratory resistive breathing against 50% maximal expiratory mouth pressure. The average distance covered in 12 min was significantly smaller during exercise with prior EMF compared to control exercise (2872 ± 256 vs. 2957 ± 325 m; P = 0.002). Running speed was consistently lower (0.13 m s⁻¹) throughout the entire 12 min of exercise with prior EMF. A significant correlation was observed between the level of EMF (decrement in maximal expiratory mouth pressure after resistive breathing) and the reduction in running distance (r ² = 0.528, P = 0.007). Perceived respiratory exertion was higher during the first 800 m and heart rate was lower throughout the entire test of running with prior EMF compared to control exercise (5.3 ± 1.6 vs. 4.5 ± 1.7 points, P = 0.002; 173 ± 10 vs. 178 ± 7 beats min⁻¹, P = 0.005). We conclude that EMF impairs exercise performance as previously reported for IMF.     

Acquired thymic tolerance and experimental allergic encephalomyelitis in the rat. I. Parameters and analysis of possible mechanisms

Intrathymic injection of guinea pig myelin basic protein (MBP) or the immunodominant, ence phalitogenic fragment of MPB, 68 – 86, without otherwise compromising the peripheral lymphocyte pool in adult LEW rats, dramatically inhibits onset of experimental allergic encephalomyelitis (EAE) caused by the usual peripheral inoculation with MBP in complete Freund's adjuvant. This surprising finding demonstrates that interaction of antigen and one or more components of an intact thymus can down-regulate systemic responses by mature T cells already existing in the peripheral lymphocyte pool. How this happens is not known. In studies designed to explore possible mechanisms: (a) adult thymectomized animals remain susceptible to active EAE, thus EAE cannot be attributed solely to recent thymic emigrants that might be inactivated by antigen deposited in the thymus; (b) heterotopic isografts of injected thymic lobes transfer thymic tolerance to secondary recipients, thus the tolerance effect is dominant over an intact, non-treated thymus; (c) T cells from made thymic tolerant but not immunized donors are less effective in causing EAE following adoptive transfer into, and active immunization of, secondary, irradiated recipients; and (d) animals resistant to active EAE as a consequence of thymic tolerance are fully vulnerable to adoptive EAE caused by already activated MBP-specific T cell subpopulations. These results rule out a possible mechanism previously proposed for acquired thymic tolerance, i. e., that potentially pathogenic T cells traffic to the antigen-injected thymus where they are inactivated or eliminated.     

Pharmacological comparison of active and passive experimental allergic encephalomyelitis in the rat

Models of actively induced and passively transferred experimental allergic encephalomyelitis (EAE) have been compared in the rat. The time of disease onset, severity of clinical symptoms and percent incidence were compared and assessed for their suitability for evaluation of immunosuppressive agents. The passive EAE model had an earlier disease onset (6±0.1 days) and 100% of the cell recipients (n=45) developed severe clinical symptoms, including paralysis of the tail and hind limbs. In contrast, the active EAE model had a mean disease onset day of 13±0.1 and only 53% of the induced rats (n=85) developed EAE clinical symptoms which were variable. The average symptom score in both models was inhibited by dexamethasone (1 mg/kg/day p.o.; day 0 to 3), methotrexate (3 mg/kg i.p. single dose; day 1) and cyclosporin A (30 mg/kg/day p.o.; day 0 to 7). The above study indicates that the passive EAE model is more advantageous for pharmacologic evaluation of immunosuppressive agents.     

Brief intense exercise followed by passive recovery modifies the pattern of fuel use in humans during subsequent sustained intermittent exercise

The role of work period duration as the principal factor influencing carbohydrate metabolism during intermittent exercise has been investigated. Fuel oxidation rates and muscle glycogen and free carnitine content were compared between two protocols of sustained intermittent intense exercise with identical treadmill speed and total work duration. In the first experiment subjects (n=6) completed 40 min of intermittent treadmill running involving a work : recovery cycle of 6 : 9 s or 24 : 36 s on separate days. With 24 : 36 s exercise a higher rate of carbohydrate oxidation approached significance (P=0.057), whilst fat oxidation rate was lower (P ≤ 0.01) and plasma lactate concentration higher (P ≤ 0.01). Muscle glycogen was lower post‐exercise with 24 : 36 s (P ≤ 0.05). Muscle free carnitine decreased (P ≤ 0.05), but there was no difference between protocols. In the second experiment a separate group of subjects (n=5) repeated the intermittent exercise protocols with the addition of a 10‐min bout of intense exercise, followed by 43 ± 5 min passive recovery, prior to sustained (40 min) intermittent exercise. For this experiment the difference in fuel use observed previously between 6 : 9 s and 24 : 36 s was abolished. Carbohydrate and fat oxidation, plasma lactate and muscle glycogen levels were similar in 6 : 9 s and 24 : 36 s. When compared with the first experiment, this result was because of reduced carbohydrate oxidation in 24 : 36 s (P ≤ 0.05). There was no difference, and no change, in muscle free carnitine between protocols. A 10‐min bout of intense exercise, followed by 43 ± 5 min of passive recovery, substantially modifies fuel use during subsequent intermittent intense exercise.     

Suppression of experimental autoimmune encephalomyelitis by intravenously administered polyclonal immunoglobulins

Experimental autoimmune encephalomyelitis (EAE) was induced in Lewis rats either by active immunization with myelin basic protein (MBP) or by adoptive transfer using anti-MBP specific CD4(+)T cells. Treatment with human polyclonal immunoglobulins (IgG) effectively suppressed active EAE. Time-dependent experiments demonstrated that the effect of IgG was manifested only when treatment was given immediately after immunization; administration from day 7 after disease induction did not suppress the disease. In the adoptive transfer model of EAE, IgG had no effect in vivo. However, pretreatment in vitro of the antigen-specific T-cells with IgG inhibited their ability to mediate adoptive EAE, as it did in active EAE. Similarly, in vitro IgG pretreatment of the antigen-specific T-cells suppressed the proliferative response to MBP. Fluorescent Activated Cell Sorter (FACS) analysis demonstrated the binding of IgG to activated T-cell lines that was inhibited by soluble Fc molecules. The differential effects of IgG on active EAE and on the adoptive transfer of EAE suggest that IgG in vivo can suppress disease by acting during the early phase of the immune response which involves naive T cells. The inhibition of T-cell proliferation and adoptive transfer of EAE by incubation of T cells in vitro appears to require higher concentrations of IgG than those obtained in vivo.     

SIRPα on CD11c+ cells induces Th17 cell differentiation and subsequent inflammation in the CNS in experimental autoimmune encephalomyelitis

Signal regulatory protein α (SIRPα) is expressed predominantly on type 2 conventional dendritic cells (cDC2s) and macrophages. We previously showed that mice systemically lacking SIRPα were resistant to experimental autoimmune encephalomyelitis (EAE). Here, we showed that deletion of SIRPα in CD11c⁺ cells of mice (Sirpa^ΔDC mice) also markedly ameliorated the development of EAE. The frequency of cDCs and migratory DCs (mDCs), as well as that of Th17 cells, were significantly reduced in draining lymph nodes of Sirpa^ΔDC mice at the onset of EAE. In addition, we found the marked reduction in the number of Th17 cells and DCs in the CNS of Sirpa^ΔDC mice at the peak of EAE. Whereas inducible systemic ablation of SIRPα before the induction of EAE prevented disease development, that after EAE onset did not ameliorate the clinical signs of disease. We also found that EAE development was partially attenuated in mice with CD11c⁺ cell-specific ablation of CD47, a ligand of SIRPα. Collectively, our results suggest that SIRPα expressed on CD11c⁺ cells, such as cDC2s and mDCs, is indispensable for the development of EAE, being required for the priming of self-reactive Th17 cells in the periphery as well as for the inflammation in the CNS.     

Effect of single-leg resistance exercise on regional arterial stiffness

To examine the effects of lower-limb unilateral resistance exercise on central and peripheral arterial stiffness, thirteen participants (7 male and 6 female, mean age = 21.5 ± 0.7 years) performed leg press exercise using their dominant leg. Pulse wave velocity (PWV) was used to measure central (carotid to femoral) and peripheral (femoral to dorsalis pedis of both legs) arterial stiffness before, 5 min post, and 25 min post exercise. No change was found in central PWV. A leg-by-time interaction was found as peripheral PWV in the non-exercised leg did not change (7.9 ± 0.3 m/s to 7.9 ± 0.3 m/s to 8.0 ± 0.3 m/s, P = 0.907) while peripheral PWV in the exercised leg significantly decreased from pre (8.7 ± 0.4 m/s) to 5 min post exercise (7.5 ± 0.3 m/s, P = 0.008) and 25 min post exercise (7.8 ± 0.3 m/s, P = 0.031). Systolic blood pressure (BP) increased significantly from pre (126.9 ± 3.4 mmHg) to 5 min post exercise (133.7 ± 4.3 mmHg, P = 0.023) and was not different than resting values 25 min post exercise (123.2 ± 3.1 mmHg). There was no change in diastolic BP. Compared to heart rate (HR) pre-exercise (55.4 ± 1.4 bpm), HR was significantly increased 5 min post exercise (70.7 ± 3.0 bpm, P = 0.001) and 25 min post exercise (69.1 ± 2.0, P = 0.001). Acute resistance exercise appears to decrease arterial stiffness in the exercised leg while having no effect on central arterial stiffness or arterial stiffness of the non-exercised leg. These findings suggest that regional changes rather than systemic alterations may influence arterial stiffness following acute resistance exercise.     

Suppression of experimental allergic encephalomyelitis in the Lewis rat by the matrix metalloproteinase inhibitor Ro31-9790

Matrix metalloproteinases (MMPs) are implicated in the tissue destruction associated with inflammatory demyelinating diseases such as multiple sclerosis. The effect of a hydroxamate inhibitor of MMPs, Ro31-9790, on inflammatory demyelination was assessed in two acute models of experimental allergic encephalomyelitis (EAE). Daily intraperitoneal injections of Ro31-9790 (50mgkg^–1), beginning either at the time of disease induction or from day 3 post induction, significantly reduced the clinical severity of adoptively transferred EAE. Administration of the inhibitor from the day of induction of active EAE prevented disease onset in 9/10 animals. However, in a repeat study, in which clinical disease was much more severe in the vehicle treated animals, the inhibitor was less effective. Clinical signs and CNS histopathology correlated well, with greater numbers of inflammatory lesions associated with increased disease severity. The present study confirms a role for the MMP cascade in inflammation in EAE.     

Diffusion tensor imaging detects treatment effects of FTY720 in experimental autoimmune encephalomyelitis mice

Fingolimod (FTY720) is an orally available sphingosine‐1‐phosphate (S1P) receptor modulator reducing relapse frequency in patients with relapsing–remitting multiple sclerosis (RRMS). In addition to immunosuppression, neuronal protection by FTY720 has also been suggested, but remains controversial. Axial and radial diffusivities derived from in vivo diffusion tensor imaging (DTI) were employed as noninvasive biomarkers of axonal injury and demyelination to assess axonal protection by FTY720 in experimental autoimmune encephalomyelitis (EAE) mice. EAE was induced through active immunization of C57BL/6 mice using myelin oligodendrocyte glycoprotein peptide 35–55 (MOG_35–55). We evaluated both the prophylactic and therapeutic treatment effect of FTY720 at doses of 3 and 10 mg/kg on EAE mice by daily clinical scoring and end‐point in vivo DTI. Prophylactic administration of FTY720 suppressed the disease onset and prevented axon and myelin damage when compared with EAE mice without treatment. Therapeutic treatment by FTY720 did not prevent EAE onset, but reduced disease severity, improving axial and radial diffusivity towards the control values without statistical significance. Consistent with previous findings, in vivo DTI‐derived axial and radial diffusivity correlated with clinical scores in EAE mice. The results support the use of in vivo DTI as an effective outcome measure for preclinical drug development. Copyright © 2013 John Wiley & Sons, Ltd.