Direct demonstration of the infiltration of murine central nervous system by Pgp-1/CD44high CD45RB(low) CD4+ T cells that induce experimental allergic encephalomyelitis.

In experimental allergic encephalomyelitis (EAE), autoimmune T cells infiltrate the central nervous system (CNS) and initiate demyelinating pathology. We have used flow cytometry to directly analyse the migration to the CNS of MBP-reactive CD4+ T cells labelled with a lipophilic fluorescent dye (PKH2), in SJL/J mice with passively transferred EAE. Labelled cells constituted about 45% of the CNS CD4+ population at the time of EAE onset. Almost all (greater than 90%) of the PKH2-labelled CD4+ T cells from EAE CNS were blasts and were alpha/beta T cell receptor (TCR)+, CD44(Pgp-1)high, and the majority were CD45RB(low). By contrast, most PKH2-labelled CD4+ T cells in lymph nodes, although CD44high, were CD45RBhigh cells. The cells that were transferred to induce EAE were essentially similar to antigen-primed lymph node cell populations, containing less than 15% CD44high cells, and most of them were CD45RBhigh. The CD44high CD45RB(low) phenotype is characteristic of memory/effector T cells that have been activated by antigen recognition. The difference in CD45RB expression between CNS and LN could therefore reflect differential exposure and/or response to antigen. Consistent with this, PKH2-labelled CD4+ cells isolated from the CNS were responsive to MBP in vitro, whereas PKH2+ CD4+ cells from lymph nodes showed almost undetectable responses. In control experiments in which ovalbumin (OVA)-reactive T cells were transferred, a small number of fluorescent-labelled CD4+ T cells were also detected in CNS, but there were very few blasts, and these remained CD45RBhigh. These results argue for induction of the memory/effector phenotype of CD4+ T cells, and their selective retention in the CNS, as a consequence of antigen recognition.     

Loss rather than downregulation of CD4 T cells as a mechanism for remission from experimental allergic encephalomyelitis

SJL/J mice recover from clinical signs of experimental allergic encephalomyelitis (EAE) 2 to 3 days following the onset of the initial attack. The immunoregulatory events that induce clinical recovery are not well understood. In this paper we have compared the activation state of the T cells infiltrating the central nervous system (CNS) in symptomatic and remitted mice. We isolated mononuclear cells from the CNS at various time points during the course of EAE and used flow cytometry to describe the kinetics of CNS infiltration by CD45⁺, CD2⁺, CD3⁺, TCRαβ⁺, CD4⁺ cells. There was a 30-fold reduction in the number of CNS CD4⁺ T cells in remitted mice 10 days following the initial attack. More than 60% of CNS CD4⁺ cells were of a CD44^high, CD45RB^low memory/effector phenotype both in active EAE, peak EAE and in remission, contrast to lymph nodes where this phenotype never constituted more than 17%. The proportion of CD8⁺ T cells was not increased in remitted mice, and we detected no TCRγδ⁺ cells within the CNS. Our findings demonstrate an overt loss of CD4⁺ T cells from the CNS and the maintenance of an activated state by T cells within the CNS and during remission from EAE. This argues against downregulation of T cell function as a mechanism for remission.     

Enhanced response to antigen within lymph nodes of SJL/J mice that were protected against experimental allergic encephalomyelitis by T cell vaccination

The effects of T cell vaccination on peripheral immune responsiveness are not yet fully understood. We have induced resistance to rat spinal cord homogenate (RSCH)-induced experimental allergic encephalomyelitis (EAE) in SJL/J mice by vaccination with four T cell lines (RZ8, RZ15, RZ16, and A51) which were reactive to myelin basic protein (MBP) but not to proteolipid protein (PLP). The effect was relatively neuroantigen-specific since vaccination with ovalbumin (OVA)-reactive and alloantigen-specific cells did not prevent EAE induction. Alloantigen-reactive cells reduced the rate of relapse. The number of central nervous system (CNS) infiltrates and mean clinical EAE scores were significantly reduced. This is the first report demonstrating T cell vaccination in the SJL/J mouse, a strain in which PLP is the predominant encephalitogen in RSCH. The vaccinating cells were of the memory/effector (CD44^high, CD45RB^low) surface phenotype. We examined the effect of T cell vaccination on lymph node T cell proliferative responses to MBP, encephalitogenic peptides of PLP and MBP, OVA and anti-CD3. With the exception of polyclonal cytokine responses to anti-CD3, which remained unchanged, vaccination led to a 5–10-fold augmentation in all, including background, responses. By comparison with lymph node cell (LNC) responses from naive mice and mice primed with OVA, it appeared that T cell vaccination restored cellular activation levels which had been depleted in peripheral lymphoid tissues of unvaccinated animals with EAE.     

Lymphokine mRNA expression in the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis is associated with a host recruited CD45R hi/CD4 population during recovery

To evaluate CD4⁺ T cell subpopulations involved in the induction and recovery from experimental autoimmune encephalomyelitis (EAE), the CD45R phenotype and lymphokine mRNA profile was evaluated for encephalitogenic CD4⁺ T cell lines in vitro and compared to CD4^* T cells islated from the spinal cord of Lewis rats with EAE were > 90% of the myelin basic protein (MBP)-specific T cell lines and clones that adoptively transferred EAE were > 90% CD4⁺ and > 90% CD45R lo. A time course of EAE disease progression was monitored as a function of the percentage of CD45R hi/CD4⁺ T cells isolated from the spinal cords of diseased animals. The majority of CD4⁺ T cells found in the central nervous system during the early phase of passive EAE were CD45R lo (the same as the encephalitogenic lines/clones). A large increase of the CD45R hi/CD4⁺ T cells (up to 45%) was observed during the peak and recovery phases of EAE. Lymphokine mRNA production was analyzed from antigen-stimulated MBP-specific lines, and from spinal cord lymphocytes isolated from rats with EAE. The BP-specific lines produced Th1 lymphokines (IL-2, IFN-γ, and TNF-α), while the spinal cord lymphocytes produced the same Th1 lymphokines as well as IL-4 and IL-10. The CD45R hi/CD4⁺ T cells isolated from the spinal cords were larger and expressed more lymphokine RNA per cell than the CD45R lo/CD4⁺ T cells. The encephalitogenic cells (CD45R hi/CD4⁺ T detected in the spinal cords of rats with a fluorescent dye and by allelic transfers and all of the CD45R hi/CD4⁺ lymphocytes found in the spinal cells were found to be host recruited. Thus it appears that the CD45R hi/CD4⁺ lymphocytes found in the spinal cord represent a host-recruited, activated cellular infiltrate that increased in number in the recovery phase of EAE and synthesized both Th1 and Th2 lymphokines.     

CD62L Treg cells with superior immunosuppressive properties accumulate within the CNS during remissions of EAE

The role of regulatory T cell populations within the CNS in the regulation of CNS-autoimmunity is controversial. We show that during recovery from relapsing remitting experimental autoimmune encephalomyelitis, regulatory T cells accumulate within the CNS that express high levels of CD62L. These CD62L^high Treg cells express increased amounts of CTLA-4, ICOS and TGF-β and are more potent than CD62L^low Treg cells in suppressing proliferation and inducing apoptosis in effector T cells. CD62L^high Treg cells thus represent a population of Treg cells that display superior immunosuppressive properties and accumulate in the CNS during recovery from CNS-autoimmunity.     

Inflammatory cells, microglia and MHC class II antigen-positive cells in the spinal cord of Lewis rats with acute and chronic relapsing experimental autoimmune encephalomyelitis

Chronic relapsing experimental autoimmune encephalomyelitis (CR-EAE) was induced in Lewis rats by inoculation with guinea pig spinal cord and adjuvants and treatment with low dose cyclosporin A (CsA). Acute EAE was induced by the same method without CsA treatment. Immunocytochemistry and flow cytometry were used to assess inflammatory cells and MHC class II (Ia) antigen expression in the central nervous system of these rats. The inflammatory infiltrate was composed mainly of CD4⁺ T cells and macrophages, and αß T cells constituted about 65% of the CD2⁺ T cells. After recovery from acute EAE and during the first remission of CR-EAE, the number of T cells was significantly less than in the preceding episodes. The number of T cells was higher in the second episode of CR-EAE than in the first remission. Throughout the course of CR-EAE, the majority of the CD2⁺ T cells were CD45RC⁻. The ratio of IL-2R⁺ cells to CD2⁺ cells ranged from 10.5 to 24.0%. The ratio of CD4⁺ T cells to B cells was lower in the later episodes of CR-EAE than in the first episode. Ia antigen was expressed on filtrating round cells at all stages of CR-EAE and on microglial cells (identified by dendritic morphology) with increasing intensity throughout the course of CR-EAE. With flow cytometry, the number of Ia⁺ cells obtained from the spinal cord rose throughout the course of CR-EAE. The number of FSC^lowOX1^low cells, which we consider represent microglia, also increased during the course of CR-EAE.     

Facilitation of experimental allergic encephalomyelitis by irradiation and virus infection: role of inflammatory cells

Infection with an avirulent strain of Semliki Forest virus (SFV-A7) facilitates the development of experimental allergic encephalomyelitis (EAE) in a genetically resistant BALB/c mouse strain. Irradiation which is necessary for EAE induction caused a decrease in the total number of lymphocytes and an increase in CD4⁺/CD8⁺ T cell ratio in the spleen of BALB/c mice. EAE induction increased the ratio further until clinical and histological signs of EAE appeared. Entry of perivascular CD4⁺ and CD8⁺ cells preceded the onset of clinical signs and the appearance of MAC-1⁺ cells in the central nervous system (CNS). In the acute phase of EAE, cellular infiltrates, which were sparse, consisted mainly of MAC-1⁺ cells and a few CD4⁺ and CD8⁺ cells. Inflammatory cells gradually disappeared during the recovery phase. SFV-A7 infection after irradiation and EAE induction did not significantly change the CD4⁺/CD8⁺ ratio in the spleen or in the CNS infiltrates but enhanced the entry of inflammatory cells into the CNS. Similar perivascular cell influx was also seen in untreated mice infected with SFV-A7. We conclude that observed rapid reduction of splenic mononuclear cells and increase of the CD4⁺/CD8⁺ T cell ratio caused by irradiation prior EAE induction are early crucial events in disease induction in this resistant strain of mice. SFV-A7 infection, which further facilitates the development of EAE, does not induce immunoregulatory changes but provides its effect by enhancing the entry of inflammatory cells into the CNS. The combination of these two mechanisms thus effectively breaks the natural resistance against EAE in this genetically resistant mouse strain.     

The effect of TCR Vβ8 peptide protection and therapy on T cell populations isolated from the spinal cords of Lewis rats with experimental autoimmune encephalomyelitis

Vaccination or treatment of Lewis rats with TCR Vβ8 peptides can prevent or reverse the clinical signs of experimental autoimmune encephalomyelitis (EAE) which is mediated predominantly by Vβ8.2⁺ CD4⁺/CD45R lo T cells. However, rats protected or treated with Vβ8 peptides still developed histological lesions in the spinal cord (SC), even though they remained clinical well. We sought to discern phenotypic changes characteristic of these SC infiltrating lymphocytes. In particular, we focused on whether the immunoregulatory mechanism induced by TCR peptides caused a reduction of Vβ8.2⁺ T cells, or induced changes in CD45R lo or hi/CD4⁺ subpopulations that have been associated respectively with EAE induction or recovery. In the Vβ8 peptide vaccinated rats there was a dramatic decrease in the number of Vβ8.2⁺ T cells isolated from the SC early in disease. During the recovery phase, however, the number of Vβ8.2⁺ SC T cells was similar in protected and control groups; in contrast, there was a striking reduction in the number and size of CD45R hi/CD4⁺ T cells in the protected animals. In rats treated with Vβ8.2 peptide, no changes were observed in the number of SC Vβ8.2⁺ T cells or expression of Vβ8.2 message, but similar to vaccinated rats, there was a marked decrease in the number of CD45R hi/CD4⁺ T cells. These data suggest that vaccination with TCR peptides prevented the initial influx of encephalitogenic Vβ8.2⁺ T cells into the central nervous system (CNS), whereas treatment appeared to inactivate Vβ8.2⁺ T cells already present in the CNS. In both cases, TCR peptide-induced inhibition of the encephalitogenic T cells apparently preempted the need for CD45R hi/CD4⁺ T cells that may normally be necessary to resolve the disease.     

Preferential increase of IL-2R+ CD4+ T cells and CD45RB- CD4+ T cells in the central nervous system in experimental allergic encephalomyelitis.

We examined lymphocytes isolated from the spinal cord (SC), peripheral blood (PB) and lymph nodes (LN) draining the immunization site of Lewis rats with acute experimental allergic encephalomyelitis (EAE). Cells were analysed for T cell subset markers CD4 (mAb W3/25) and CD8 (mAb OX8), for IL-2R (mAb OX39), and for high molecular mass leukocyte common antigen (LCA, CD45RB) expression (mAb OX22). T cells expressing high (CD45RB+) or low (CD45RB-) molecular mass LCA are of different maturational stages and/or separate lineages. CD4+ T cells were more predominant in SC than in PB and LN; CD8+ T cells were scarce in SC but common in PB and LN. Activated CD4+ T cells (IL-2R+) were common in the SC and LN but infrequent in blood. CD4+ T cells that were CD45RB+ were scarce in the SC. In contrast, the majority of CD4+ T cells in the PB and LN were CD45RB+. The preferential accumulation of IL-2R+ CD4+ T cells and of CD45RB- CD4+ T cells in the central nervous system (CNS) indicates that a selective mechanism directs cell egress into CNS lesions in EAE.     

The subarachnoid space as a site for precursor T cell proliferation and effector T cell selection in experimental autoimmune encephalomyelitis

To characterize the phenotype of inflammatory cells in the central nervous system (CNS) in experimental autoimmune encephalomyelitis (EAE), Lewis rats were immunized with guinea pig myelin basic protein and frozen sections of the spinal cord with EAE were examined immunohistochemically using a panel of monoclonal antibodies against T cells and adhesion molecules. In addition, double immunostaining was performed with glial and T cells markers to examine the interaction between infiltrating T cells and reactive brain cells during the course of EAE. In the early stage of EAE, inflammatory cells first appeared in the subarachnoid space (SAS) and infiltrated the subpial region. The majority of inflammatory cells in SAS expressed TCRaβ and either CD4 or CD8 molecules. However, only CD4⁺ T cells infiltrated the parenchyma while the majority of CD8⁺ cells remained in SAS. A similar differential localization of T cells was observed with regard to CD45RC molecules. Inflammatory cells in SAS consisted of both CD45RC⁺ and CD45RC^- population, while those in the parenchyma were largely CD45RC˜. With regard to adhesion molecules, the leptomeninges constitutively expressed fibronectin (FN) and intercellular adhesion molecule 1 (ICAM-1). Most SAS inflammatory cells expressed very late activation antigen 4 (VLA-4) and, to lesser extent, lymphocyte function-associated antigen 1 (LFA-1) in the early stage of EAE. On the other hand, parenchyma! infiltrating cells expressed LFA-1 more strongly in the peak stage. Double staining for Vβ8.2 TCR and microglia demonstrated an increase in the number of microglia together with morphological changes into rod-shape cells in the vicinity of infiltrating T cells. Furthermore, these cells expressed adhesion molecules, such as LFA-1, ICAM-1 and CD4. These findings suggest that VLA-4/FN and LFA-1/ICAM-1 interactions between infiltrating cells and brain cells may be involved in the early and peak stages of EAE. Phenotype switching occurring in the process of inflammatory cell infiltration may be regulated by these adhesion molecules and factor(s) provided by the parenchyma, possibly by microglia.     

Infiltration of Th1 and Th17 cells and activation of microglia in the CNS during the course of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a mouse model for multiple sclerosis, where disease is mediated by autoantigen-specific T cells. Although there is evidence linking CD4⁺ T cells that secrete IL-17, termed Th17 cells, and IFN-γ-secreting Th1 cells with the pathogenesis of EAE, the precise contribution of these T cell subtypes or their associated cytokines is still unclear. We have investigated the infiltration of CD4⁺ T cells that secrete IFN-γ, IL-17 or both cytokines into CNS during development of EAE and have examined the role of T cells in microglial activation. Our findings demonstrate that Th17 cells and CD4⁺ T cells that produce both IFN-γ and IL-17, which we have called Th1/Th17 cells, infiltrate the brain prior to the development of clinical symptoms of EAE and that this coincides with activation of CD11b⁺ microglia and local production of IL-1β, TNF-α and IL-6 in the CNS. In contrast, significant infiltration of Th1 cells was only detected after the development of clinical disease. Co-culture experiments, using mixed glia and MOG-specific T cells, revealed that T cells that secreted IFN-γ and IL-17 were potent activators of pro-inflammatory cytokines but T cells that secrete IFN-γ, but not IL-17, were less effective. In contrast both Th1 and Th1/Th17 cells enhanced MHC-class II and co-stimulatory molecule expression on microglia. Our findings suggest that T cells which secrete IL-17 or IL-17 and IFN-γ infiltrate the CNS prior to the onset of clinical symptoms of EAE, where they may mediate CNS inflammation, in part, through microglial activation.     

The activation of monocyte and T cell networks in patients with bipolar disorder

Objectives

We recently described a monocyte pro-inflammatory state in patients with bipolar disorder (BD). We hypothesized that the CD4⁺T cell system is also activated and determined percentages of Th1, Th2, Th17 and CD4⁺CD25^highFoxP3⁺ regulatory T cells.

Methods

We carried out a detailed FACS analysis to determine the various T cell subsets and used frozen stored peripheral blood mononuclear cells (PBMC) of 38 BD patients (of whom we previously had tested monocytes for pro-inflammatory gene expression ( [Drexhage et al., 2010a] and [Padmos et al., 2008])) and of 22 age/gender matched healthy controls (HC). In addition the cytokines CCL2, IL-1β, IL-6, TNF-α, PTX3, IL-10, IFN-γ, IL-17A, IL-4, IL-5 and IL-22 were measured in serum.

Results

(a) Serum sCD25 levels and percentages of anti-inflammatory CD4⁺CD25^highFoxP3+ regulatory T cells were higher, the latter in BD patients <40 years of age. Percentages of Th1, Th2 and Th17 cells were normal.(b) Of the pro-inflammatory monocyte cytokines CCL2 and PTX3 were raised in serum.(c) The monocyte pro-inflammatory state and the raised percentages of CD4⁺CD25^highFoxP3⁺ regulatory T cells occurred independently from each other.(d) In BD patients positive for thyroid autoimmune disease a significantly reduced percentage of CD4⁺CD25^highFoxP3⁺ regulatory T cells was found as compared to BD patients without AITD.

Conclusion

Our data show an enhancement of pro-inflammatory monocyte and anti-inflammatory T cell forces in BD patients. A lack of anti-inflammatory T cell forces co-occurred with AITD in BD patients.     

Respiratory infection with a bacterial pathogen attenuates CNS autoimmunity through IL-10 induction

Infection with viral or bacterial pathogens has been linked with the development of multiple sclerosis (MS), while infection with helminth parasites has been associated protection against MS and other autoimmune diseases. Here we have used a murine model of MS, experimental autoimmune encephalomyelitis (EAE), to examine the effect of infection with the respiratory pathogen Bordetella pertussis infection on development of CNS inflammation. The data demonstrate that infection of mice with B. pertussis significantly attenuates the clinical course of EAE induced by active immunization or cell transfer. This was reflected in a significant reduction in VLA-4 and LFA-1 expression on T cells and infiltration of IL-17⁺, IFN-γ⁺ and IFN-γ⁺IL-17⁺ CD4 T cells into the CNS. Infection with B. pertussis induced IL-10 production from dendritic cells in vitro and enhanced the frequency of IL-10-producing CD25^-Foxp3^+/− CD4⁺ T cells in vivo. Furthermore, the suppressive effects of B. pertussis infection on EAE were lost in IL-10^−/− mice. Our findings demonstrate that a bacterial infection of the respiratory tract can attenuate EAE by promoting production of the anti-inflammatory cytokine IL-10 that may suppress licensing of autoaggressive T cells in the lungs, thereby preventing their migration into the CNS.     

In acute experimental autoimmune encephalomyelitis,infiltrating macrophages are immune activated,whereas microglia remain immune suppressed

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS) characterized by loss of myelin accompanied by infiltration of T‐lymphocytes and monocytes. Although it has been shown that these infiltrates are important for the progression of MS, the role of microglia, the resident macrophages of the CNS, remains ambiguous. Therefore, we have compared the phenotypes of microglia and macrophages in a mouse model for MS, experimental autoimmune encephalomyelitis (EAE). In order to properly discriminate between these two cell types, microglia were defined as CD11b^pos CD45^int Ly‐6C^neg, and infiltrated macrophages as CD11b^pos CD45^high Ly‐6C^pos. During clinical EAE, microglia displayed a weakly immune‐activated phenotype, based on the expression of MHCII, co‐stimulatory molecules (CD80, CD86, and CD40) and proinflammatory genes [interleukin‐1β (IL‐1β) and tumour necrosis factor‐ α (TNF‐α)]. In contrast, CD11b^pos CD45^high Ly‐6C^pos infiltrated macrophages were strongly activated and could be divided into two populations Ly‐6C^int and Ly‐6C^high, respectively. Ly‐6C^high macrophages contained less myelin than Ly‐6C^int macrophages and expression levels of the proinflammatory cytokines IL‐1β and TNF‐α were higher in Ly‐6C^int macrophages. Together, our data show that during clinical EAE, microglia are only weakly activated whereas infiltrated macrophages are highly immune reactive. GLIA 2014;62:1724–1735     

Memory cells specific for myelin oligodendrocyte glycoprotein (MOG) govern the transfer of experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an inflammatory disease of the CNS mediated by CD4(+) T cells directed against myelin antigens. Experimental autoimmune encephalomyelitis (EAE) is induced by immunization with myelin antigens like myelin oligodendrocyte glycoprotein (MOG). We have explored the transfer of EAE using MOG(35-55)-specific TCR transgenic (2D2) T cells. Unsorted 2D2 Th1 cells reliably transferred EAE. Further, we found that CD44(hi)CD62L(lo) effector/memory CD4(+) T cells are likely responsible for the disease transfer due to the up-regulation of CD44. Given the importance of MOG in MS pathogenesis, mechanistic insights into adoptively transferred EAE by MOG-specific Th1 cells could prove valuable in MS research.     

PECAM-1 (CD31) expression in the central nervous system and its role in experimental allergic encephalomyelitis in the rat

The role of T cell activation associated adhesion molecules on lymphocyte traffic and the initiation of inflammation has received considerable attention. This study, using a new monoclonal antibody (mAb) TLD-3A12, describes the distribution of PECAM-1 (CD31), an Ig supergene family adhesion molecule thought to be important in leukocyte transmigration during inflammation, in rat lymphoid organs and spinal cord. PECAM expression within the CNS is confined to endothelial cells of the blood brain barrier (BBB). Induction of inflammation within the CNS using the adoptive transfer of myelin reactive CD4⁺ T cells results in the de novo expression of immune adhesion and accessory molecules in the spinal cord, while the level of PECAM appeared only mildly increased. The distribution of PECAM on CNS endothelial cells became more diffuse during EAE induction, possibly the result of endothelial cell activation. In vitro studies demonstrate a partial inhibition of antigen-specific CD4⁴ T cell proliferation following anti-PECAM mAb treatment. Treatment of Lewis rats with TLD-3A12 antibody prior to T cell injection and throughout EAE induction does not result in a delay in the onset of clinical signs or weight loss, nor does it decrease the incidence and severity of disease. These data suggest that the expression of PECAM by CNS endothelial cells is not a requirement for the initiation of inflammation and clinical signs of EAE following the adoptive transfer of encephalitogenic lymphocytes. Thus, cells requiring PECAM-1 to migrate and perform their pathogenic functions are not critical to the development of rat EAE. © 1996 Wiley-Liss, Inc.     

Tellurium Compound AS101 Ameliorates Experimental Autoimmune Encephalomyelitis by VLA-4 Inhibition and Suppression of Monocyte and T Cell Infiltration into the CNS

Multiple sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system (CNS) involving demyelinating and neurodegenerative processes. Several of the major pathological CNS alterations and behavioral deficits of MS are recapitulated in the experimental autoimmune encephalitis (EAE) mouse model in which the disease process is induced by administration of myelin peptides. Development of EAE requires infiltration of inflammatory cytokine-generating monocytes and macrophages, and auto-reactive T cells, into the CNS. Very late antigen-4 (VLA-4, α4β1) is an integrin molecule that plays a role in inflammatory responses by facilitating the migration of leukocytes across the blood–brain barrier during inflammatory disease, and antibodies against VLA-4 exhibit therapeutic efficacy in mouse and monkey MS models. Here, we report that the tellurium compound AS101 (ammonium trichloro (dioxoethylene-o,o′) tellurate) ameliorates EAE by inhibiting monocyte and T cell infiltration into the CNS. CD49d is an alpha subunit of the VLA-4 (α4β1) integrin. During the peak stage of EAE, AS101 treatment effectively ameliorated the disease process by reducing the number of CD49d⁺ inflammatory monocyte/macrophage cells in the spinal cord. AS101 treatment markedly reduced the pro-inflammatory cytokine levels, while increasing anti-inflammatory cytokine levels. In contrast, AS101 treatment did not affect the peripheral populations of CD11b⁺ monocytes and macrophages. AS101 treatment reduced the infiltration of CD4⁺ and CD49⁺/VLA4 T cells. In addition, treatment of T cells from MS patients with AS101 resulted in apoptosis, while such treatment did not affect T cells from healthy donors. These results suggest that AS101 reduces accumulation of leukocytes in the CNS by inhibiting the activity of the VLA-4 integrin and provide a rationale for the potential use of Tellurium IV compounds for the treatment of MS.     

Effector and suppressor roles for LFA-1 during the development of experimental autoimmune encephalomyelitis

LFA-1 (CD11a/CD18) is a member of the β₂-integrin family of adhesion molecules important in leukocyte trafficking and activation. Although LFA-1 is thought to contribute to the development of experimental autoimmune encephalomyelitis (EAE) primarily through its functions on effector T cells, its importance on other leukocyte populations remains unexplored. To address this question, we performed both adoptive transfer EAE experiments involving CD11a^?/? mice and trafficking studies using bioluminescent T cells expressing luciferase under the control of a CD2 promoter (T-lux cells). Transfer of encephalitogenic CD11a^?/? T cells to wild type mice resulted in a significant reduction in overall EAE severity compared to control transfers. We also observed, using in vivo imaging techniques, that CD11a^?/? T-lux cells readily infiltrated lymph nodes and the CNS of wild type recipients with kinetics comparable to CD11a^+/+ transfers, although their overall numbers in these organs were reduced. Surprisingly, transfer of encephalitogenic wild type T cells to CD11a^?/? mice induced a severe and sometimes fatal EAE disease course, associated with massive T cell infiltration and proliferation in the CNS. These data indicate that LFA-1 expression on leukocytes in recipient mice plays an important immunomodulatory role in EAE. Thus, LFA-1 acts as a key regulatory adhesion molecule during the development of EAE, serving both pro- and anti-inflammatory roles in disease pathogenesis.     

IL-23 modulated myelin-specific T cells induce EAE via an IFNγ driven, IL-17 independent pathway

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system (CNS) mediated by myelin-reactive CD4⁺ T cells. An unresolved issue that has important clinical implications concerns the cytokines produced by myelin-reactive T cells that determine their pathogenicity. Initially, IL-12 polarized, IFNγ producing Th1 cells were thought to be essential for the development of EAE. More recently, IL-23 polarized, IL-17 producing Th17 cells have been highlighted as critical encephalitogenic effectors. There is growing evidence that parallel autoimmune pathways can result in common clinical and histopathological endpoints. In the current study, we describe a form of EAE induced by the transfer of IL-23 modulated CD4⁺ T cells into IL-17 receptor (IL-17R) deficient hosts. We found that IL-23 stimulates myelin-reactive T cells to produce both IFNγ and IL-17. Surprisingly, in this model the development of EAE is IFNγ dependent. Our findings illustrate a novel mechanism by which IL-23 promotes encephalitogenicity and they further expand the spectrum of autoreactive T cells capable of mediating inflammatory demyelinating disease of the CNS.     

Bothanti-CD11a(LFA-l) and anti-CD11b (MAC-1) therapy delay the onset and diminish the severity of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease of the central nervous system (CNS) induced in rodents by activated CD4⁺ T cells specific for various myelin proteins such as myelin basic protein and proteolipid protein. The disease is characterized by breach of the blood-brain barrier, perivascular infiltration of leukocytes into the CNS, local inflammation and demyelination in the form of plaques. In this study, we evaluated the effect of administration of antibodies to two members of the β2 integrin sub-family of adhesion molecules, CD11a and CD11b, on the onset and progression of EAE. CD11a and CD11b are involved in cell-cell interactions leading to T cell and macrophage extravasation to inflammatory sites and T cell activation. Our results show that anti-CD11a antibodies could completely block the induction of EAE and anti-CD11b antibodies significantly delayed the onset and diminished the severity of clinical signs of EAE even when injections were initiated at the first appearance of clinical signs.