Interferon-? secretion by peripheral blood T-cell subsets in multiple sclerosis: Correlation with disease phase and interferon-? therapy

The significance of structural rich club hubs for the processing of hierarchical stimuli

The brain's structural network follows a hierarchy that is described as rich club (RC) organization, with RC hubs forming the well-interconnected top of this hierarchy. In this study, we tested whether RC hubs are involved in the processing of hierarchically higher structures in stimulus sequences. Moreover, we explored the role of previously suggested cortical gradients along anterior-posterior and medial-lateral axes throughout the frontal cortex. To this end, we conducted a functional magnetic resonance imaging (fMRI) experiment and presented participants with blocks of digit sequences that were structured on different hierarchically nested levels. We additionally collected diffusion weighted imaging data of the same subjects to identify RC hubs. This classification then served as the basis for a region of interest analysis of the fMRI data. Moreover, we determined structural network centrality measures in areas that were found as activation clusters in the whole-brain fMRI analysis. Our findings support the previously found anterior and medial shift for processing hierarchically higher structures of stimuli. Additionally, we found that the processing of hierarchically higher structures of the stimulus structure engages RC hubs more than for lower levels. Areas involved in the functional processing of hierarchically higher structures were also more likely to be part of the structural RC and were furthermore more central to the structural network. In summary, our results highlight the potential role of the structural RC organization in shaping the cortical processing hierarchy.

The CD8 T Cell-Epstein-Barr Virus-B Cell Trialogue: A Central Issue in Multiple Sclerosis Pathogenesis

The cause and the pathogenic mechanisms leading to multiple sclerosis (MS), a chronic inflammatory disease of the central nervous system (CNS), are still under scrutiny. During the last decade, awareness has increased that multiple genetic and environmental factors act in concert to modulate MS risk. Likewise, the landscape of cells of the adaptive immune system that are believed to play a role in MS immunopathogenesis has expanded by including not only CD4 T helper cells but also cytotoxic CD8 T cells and B cells. Once the key cellular players are identified, the main challenge is to define precisely how they act and interact to induce neuroinflammation and the neurodegenerative cascade in MS. CD8 T cells have been implicated in MS pathogenesis since the 80's when it was shown that CD8 T cells predominate in MS brain lesions. Interest in the role of CD8 T cells in MS was revived in 2000 and the years thereafter by studies showing that CNS-recruited CD8 T cells are clonally expanded and have a memory effector phenotype indicating in situ antigen-driven reactivation. The association of certain MHC class I alleles with MS genetic risk implicates CD8 T cells in disease pathogenesis. Moreover, experimental studies have highlighted the detrimental effects of CD8 T cell activation on neural cells. While the antigens responsible for T cell recruitment and activation in the CNS remain elusive, the high efficacy of B-cell depleting drugs in MS and a growing number of studies implicate B cells and Epstein-Barr virus (EBV), a B-lymphotropic herpesvirus that is strongly associated with MS, in the activation of pathogenic T cells. This article reviews the results of human studies that have contributed to elucidate the role of CD8 T cells in MS immunopathogenesis, and discusses them in light of current understanding of autoreactivity, B-cell and EBV involvement in MS, and mechanism of action of different MS treatments. Based on the available evidences, an immunopathological model of MS is proposed that entails a persistent EBV infection of CNS-infiltrating B cells as the target of a dysregulated cytotoxic CD8 T cell response causing CNS tissue damage.

Expression analysis of NF-κB-associated long noncoding RNAs in peripheral blood mononuclear cells from relapsing-remitting multiple sclerosis patients

Long noncoding RNAs (lncRNAs) as potential disease biomarkers might be related to severe course of multiple sclerosis (MS). We evaluated expression levels of NF-κB-associated lncRNAs including HOTAIR, THRIL, H19, NKILA, and ANRIL; as well as expression of IL-6, TNF-α and MMP9, in peripheral blood mononuclear cells (PBMCs) from 60 relapse-remitting MS (RRMS) patients. At relapse phase of RRMS, up-regulation of ANRIL and H19 was positively correlated with the overexpression of IL-6; high levels of THRIL and HOTAIR was positively correlated with increased levels of TNF-α and MMP9, respectively; however, the NKILA expression was negatively correlated with the expression of TNF-α.

Syncytin-1/HERV-W envelope is an early activation marker of leukocytes and is upregulated in multiple sclerosis patients

Syncytin-1 is the envelope protein of the human endogenous retrovirus W (HERV-W). It has been related to multiple sclerosis (MS) but its role in cellular immunity and its pathogenic mechanism in the autoimmune context are not fully understood. We analyzed syncytin-1 levels in peripheral blood mononuclear cells (PBMC) subsets from healthy donors, MS patients in relapse or remission, and patients with acute infections by flow cytometry. PBMC cultures were also prepared to analyze protein expression kinetics. MS patients had higher levels of syncytin-1 levels than controls. We found that syncytin-1 is elevated in monocytes during MS relapses and infections. Cells expressing syncytin-1, including monocytes, T and B lymphocytes, and NKs presented mainly an activated phenotype and, upon stimulation with LPS, its levels increased rapidly on antigen-presenting cells. Syncytin-1 ligation promoted the activation of monocytes, as demonstrated by the upregulation of CD80 and the nonclassical subset CD14^low CD16⁺ . Our results suggest an important role for syncytin-1 in the activation of leukocytes. Given that the expression of syncytin-1 is upregulated in MS patients, this protein might be contributing to the autoimmune cascade in the disease.

Reactive astrocytes in multiple sclerosis impair neuronal outgrowth through TRPM7-mediated chondroitin sulfate proteoglycan production

Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system (CNS), characterized by inflammation‐mediated demyelination, axonal injury and neurodegeneration. The mechanisms underlying impaired neuronal function are not fully understood, but evidence is accumulating that the presence of the gliotic scar produced by reactive astrocytes play a critical role in these detrimental processes. Here, we identified astrocytic Transient Receptor Potential cation channel, subfamily M, member 7 (TRPM7), a Ca²⁺‐permeable nonselective cation channel, as a novel player in the formation of a gliotic scar. TRPM7 was found to be highly expressed in reactive astrocytes within well‐characterized MS lesions and upregulated in primary astrocytes under chronic inflammatory conditions. TRPM7 overexpressing astrocytes impaired neuronal outgrowth in vitro by increasing the production of chondroitin sulfate proteoglycans, a key component of the gliotic scar. These findings indicate that astrocytic TRPM7 is a critical regulator of the formation of a gliotic scar and provide a novel mechanism by which reactive astrocytes affect neuronal outgrowth.

On the horizon: possible neuroprotective role for glatiramer acetate

Inflammation and neurodegeneration characterize the pathogenesis of multiple sclerosis (MS). Slow axonal degeneration, rather than acute inflammation, is considered the cause of chronic disability in MS. The signs of acute axonal damage and loss have been shown to occur early in the lesion development of patients with chronic MS and often correlate with demyelination and inflammation. While immune activity in the central nervous system has traditionally been considered to be a detrimental event in MS, recent studies have found that autoimmune T cells may play an important role in protecting neurons from the ongoing spreading damage. Neuroprotectio n in MS is a new and evolving concept, and many questions remain with regard to potential targets for therapeutic intervention. Preliminary studies, both in animals and in humans, have suggested that glatiramer acetate (GA) may confer neuroprotective activity in addition to bystander suppression. Additional research is needed to determine if these promising neuroprotective effects correlate with the long-term effect of G A in MS.

Differential Frequency of CD8+ T Cell Subsets in Multiple Sclerosis Patients with Various Clinical Patterns

Recent evidence points to a pathogenic role for CD8⁺ cytotoxic T (Tc) cells in Multiple sclerosis (MS). Based on cytokine profile, Tc cells can be divided into different subsets: IFN-γ (Tc1), IL-4 (Tc2), IL-10 (Tc10), IL-17 (Tc17), IL-21 (Tc21), IL-22 (Tc22) and TNF-α producing cells. In this study we evaluated the frequency of Tc cell subsets and the serum level of Tc17 differentiation cytokines in MS patients with different clinical patterns. We analyzed Tc cell subsets percentage in peripheral blood of relapsing-remitting (RRMS) (n = 28), secondary-progressive (SPMS) (n = 10) and primary-progressive (PPMS) (n = 4) MS patients in comparison to healthy controls (n = 15) using flow cytometry. Serum level of TGF-β, IL-6 and IL-23 were measured by ELISA. We showed elevated levels of Tc1 and Tc17 cells in SPMS and RRMS patients in relapse phase, respectively (P = 0.04). Interestingly, the percentage of TNF-α producing CD8⁺ T cells in relapse and remission phase of RRMS and SPMS patients were higher than controls (P = 0.01, P = 0.004, P = 0.01, respectively) and Tc21 increased in remission phase of RRMS compared to SPMS (P = 0.03). We also found higher frequency of CD8⁺ IFN-γ⁺ TNF-α⁺ IL-17⁺ T cells in relapse phase of RRMS compared to remission phase, SPMS patients and controls (P = 0.01, P = 0.004 and P = 0.02, respectively). TGF- β increased in sera of RRMS patients in remission phase (P = 0.03) and SPMS (P = 0.05) compared to healthy subjects. Increased level of Tc17 and CD8⁺ IFN-γ⁺ TNF-α⁺ IL-17⁺ T cells in relapse phase highlights the critical role of IL-17 in RRMS pathogenesis.

Secondary Progressive Multiple Sclerosis: Definition and Measurement

Secondary progressive multiple sclerosis (SPMS) is diagnosed retrospectively and involves a clinical course characterized by a progressive accumulation of neurological disability, independent of relapses, following an initial relapsing-remitting (RR) phase. Our incomplete understanding of the pathological mechanisms underlying neurodegeneration in multiple sclerosis (MS) may explain why, to date, there is no definitive imaging or laboratory test that is able to inform us when the disease is clearly entering into a progressive phase and why the vast majority of clinical trials testing immunosuppressant and immunomodulating drugs in SPMS patients has so far yielded disappointing or mixed results. Here we discuss the definition(s) of SPMS and how it may vary, outcome measurements (current and emerging) and modern trial design.

Differential expression of glucose-metabolizing enzymes in multiple sclerosis lesions

Introduction

Demyelinated axons in multiple sclerosis (MS) lesions have an increased energy demand in order to maintain conduction. However, oxidative stress-induced mitochondrial dysfunction likely alters glucose metabolism and consequently impairs neuronal function in MS. Imaging and pathological studies indicate that glucose metabolism is altered in MS, although the underlying mechanisms and its role in neurodegeneration remain elusive. We investigated expression patterns of key enzymes involved in glycolysis, tricarboxylic acid (TCA) cycle and lactate metabolism in well-characterized MS tissue to establish which regulators of glucose metabolism are involved in MS and to identify underlying mechanisms.

Results

Expression levels of glycolytic enzymes were increased in active and inactive MS lesions, whereas expression levels of enzymes involved in the TCA cycle were upregulated in active MS lesions, but not in inactive MS lesions. We observed reduced expression and production capacity of mitochondrial α-ketoglutarate dehydrogenase (αKGDH) in demyelinated axons, which correlated with signs of axonal dysfunction. In inactive lesions, increased expression of lactate-producing enzymes was observed in astrocytes, whereas lactate-catabolising enzymes were mainly detected in axons. Our results demonstrate that the expression of various enzymes involved in glucose metabolism is increased in both astrocytes and axons in active MS lesions. In inactive MS lesions, we provide evidence that astrocytes undergo a glycolytic shift resulting in enhanced astrocyte-axon lactate shuttling, which may be pivotal for the survival of demyelinated axons.

Conclusion

In conclusion, we show that key enzymes involved in energy metabolism are differentially expressed in active and inactive MS lesions. Our findings imply that, in addition to reduced oxidative phosphorylation activity, other bioenergetic pathways are affected as well, which may contribute to ongoing axonal degeneration in MS.

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-015-0261-8) contains supplementary material, which is available to authorized users.

Inhibition of G-Protein βγ Signaling Decreases Levels of Messenger RNAs Encoding Proinflammatory Cytokines in T Cell Receptor-Stimulated CD4(+) T Helper Cells

Background: Inhibition of G-protein βγ (Gβγ) signaling was found previously to enhance T cell receptor (TCR)-stimulated increases in interleukin 2 (IL-2) mRNA in CD4⁺ T helper cells, suggesting that Gβγ might be a useful drug target for treating autoimmune diseases, as low dose IL-2 therapy can suppress autoimmune responses. Because IL-2 may counteract autoimmunity in part by shifting CD4⁺ T helper cells away from the Type 1 T helper cell (TH1) and TH17 subtypes towards the TH2 subtype, the purpose of this study was to determine if blocking Gβγ signaling affected the balance of TH1, TH17, and TH2 cytokine mRNAs produced by CD4⁺ T helper cells.

Methods: Gallein, a small molecule inhibitor of Gβγ, and siRNA-mediated silencing of the G-protein β₁ subunit (Gβ₁) were used to test the effect of blocking Gβγ on mRNA levels of cytokines in primary human TCR-stimulated CD4⁺ T helper cells.

Results: Gallein and Gβ₁ siRNA decreased interferon-γ (IFN-γ) and IL-17A mRNA levels in TCR-stimulated CD4⁺ T cells grown under TH1-promoting conditions. Inhibiting Gβγ also decreased mRNA levels of STAT4, which plays a positive role in TH1 differentiation and IL-17A production. Moreover, mRNA levels of the STAT4-regulated TH1-associated proteins, IL-18 receptor β chain (IL-18Rβ), mitogen-activated protein kinase kinase kinase 8 (MAP3K8), lymphocyte activation gene 3 (LAG-3), natural killer cell group 7 sequence (NKG7), and oncostatin M (OSM) were also decreased upon Gβγ inhibition. Gallein also increased IL-4, IL-5, IL-9, and IL-13 mRNA levels in TCR-stimulated memory CD4⁺ T cells grown in TH2-promoting conditions.

Conclusions: Inhibiting Gβγ to produce these shifts in cytokine mRNA production might be beneficial for patients with autoimmune diseases such as rheumatoid arthritis (RA), Crohn’s disease (CD), psoriasis, multiple sclerosis (MS), and Hashimoto’s thyroiditis (HT), in which both IFN-γ and IL-17A are elevated.

Stage-specific immune dysregulation in multiple sclerosis

A large body of data indicates that multiple sclerosis (MS) is an autoimmune disease which is initiated by CD4(+) T-helper 1 (Th1) and Th17 cells that are reactive against proteins in the myelin sheath. MS typically begins with a relapsing-remitting course, punctuated by clinical exacerbations associated with the development of focal inflammatory lesions in central nervous system white matter, followed by a secondary progressive (SP) phase, characterized by a gradual accumulation of neurological disability associated with widespread microglial activation and axonal loss. The molecular and cellular basis for this transition is unclear, and the role of inflammation during the SP stage is a subject of active debate. As of now, no immunological biomarkers have been identified in MS that are predictive of the clinical course or therapeutic responsiveness to disease-modifying agents, or that correlate with new lesion development, cumulative lesion load, or degree of disability. The discovery of such biomarkers would greatly facilitate clinical management and provide power for smaller and shorter clinical trials. In this article, we discuss the literature on immunological biomarkers in MS with a focus on stage-specific differences and similarities.

Astroglial PGC-1alpha increases mitochondrial antioxidant capacity and suppresses inflammation: implications for multiple sclerosis

Recent evidence suggests that reactive oxygen species (ROS) produced by inflammatory cells drive axonal degeneration in active multiple sclerosis (MS) lesions by inducing mitochondrial dysfunction. Mitochondria are endowed with a variety of antioxidant enzymes, including peroxiredoxin-3 and thioredoxin-2, which are involved in limiting ROS-induced damage. In this study, we explored the distribution and role of the mitochondrial antioxidants peroxiredoxin-3 and thioredoxin-2 as well as their regulator peroxisome proliferator-activated receptor gamma coactivator1-alpha (PGC-1α) in MS pathogenesis.

Immunohistochemical analysis of a large cohort of MS patients revealed a striking upregulation of PGC-1α and downstream mitochondrial antioxidants in active demyelinating MS lesions. Enhanced expression was predominantly observed in reactive astrocytes. To elucidate the functional role of astrocytic PGC-1α in MS pathology, we generated human primary astrocytes that genetically overexpressed PGC-1α. Upon an oxidative insult, these cells were shown to produce less ROS and were found to be more resistant to ROS-induced cell death compared to control cells. Intriguingly, also neuronal cells co-cultured with PGC-1α-overexpressing astrocytes were protected against an exogenous oxidative attack compared to neuronal cells co-cultured with control astrocytes. Finally, enhanced astrocytic PGC-1α levels markedly reduced the production and secretion of the pro-inflammatory mediators interleukin-6 and chemokine (C-C motif) ligand 2. Our findings suggest that increased astrocytic PGC-1α in active MS lesions might initially function as an endogenous protective mechanism to dampen oxidative damage and inflammation thereby reducing neurodegeneration. Activation of PGC-1α therefore represents a promising therapeutic strategy to improve mitochondrial function and repress inflammation.

Astrocyte-derived retinoic acid: a novel regulator of blood-brain barrier function in multiple sclerosis

Multiple sclerosis (MS) lesions are characterized by the presence of activated astrocytes, which are thought to actively take part in propagating lesion progression by secreting pro-inflammatory mediators. Conversely, reactive astrocytes may exert disease-dampening effects through the production of trophic factors and anti-inflammatory mediators. Astrocytic control of the blood-brain barrier (BBB) is crucial for normal brain homeostasis and BBB disruption is a well-established early event in MS lesion development. Here, we set out to unravel potential protective effects of reactive astrocytes on BBB function under neuroinflammatory conditions as seen in MS, where we focus on the role of the brain morphogen retinoic acid (RA). Immunohistochemical analysis revealed that retinaldehyde dehydrogenase 2 (RALDH2), a key enzyme for RA synthesis, is highly expressed by reactive astrocytes throughout white matter lesions compared to control and normal appearing white matter. In vitro modeling of reactive astrocytes resulted in increased expression of RALDH2, enhanced RA synthesis, and a protective role for astrocyte-derived RA on BBB function during inflammation-induced barrier loss. Furthermore, RA induces endothelial immune quiescence and decreases monocyte adhesion under inflammatory conditions. Finally, we demonstrated that RA attenuated oxidative stress in inflamed endothelial cells, through activation of the antioxidant transcription factor nuclear factor E2 related factor 2. In summary, RA synthesis by reactive astrocytes represents an endogenous protective response to neuroinflammation, possibly aimed at protecting the BBB against inflammatory insult. A better understanding of RA signaling in MS pathophysiology may lead to the discovery of novel targets to halt disease progression.

Fraction of IL-10+ and IL-17+ CD8 T cells is increased in MS patients in remission and during a relapse, but is not influenced by immune modulators

In the present study, circulating proportions of CD8(+) T (Tc) cell subsets, including IL-17 (Tc17) and IL-10 (Tc10) producing cells, were assessed in relapsing-remitting MS (RRMS) patients and a possible effect of beta interferon (IFN-β), glatiramer acetate (GA), and vitamin D (VitD) on these cell subsets was investigated. We show that both Tc17 and Tc10 cell fractions are elevated in the circulation of RRMS patients in remission compared to healthy subjects and that these Tc subsets remain unaffected by current immune modulating regimens.

Cytokine profile in relapsing‑remitting multiple sclerosis patients and the association between progression and activity of the disease

Multiple sclerosis (MS) is a progressive immune‑ mediated disease caused by demyelination of the central nervous system. Cytokines and their receptors have an important role in the evolution of MS lesions, and pro‑ and anti‑inflammatory cytokine levels have been found to correlate with changes in MS disease activity. The aims of the present study were to evaluate the pro‑inflammatory [tumor necrosis factor (TNF)‑α and interleukin (IL) ‑1β, ‑6 and ‑12], T helper (Th) 1 [interferon (IFN)‑γ], Th17 (IL‑17) and Th2 (IL‑4 and ‑10) cytokine serum levels in relapsing‑remitting (RR)‑MS patients and to evaluate the association between the cytokine profile and the progression and activity of the disease. Serum cytokine levels were assessed using enzyme linked‑immunosorbent assays in 169 RR‑MS patients in the remission clinical phase and 132 healthy individuals who were age‑, gender‑, ethnicity‑ and body mass index‑matched. Disability and activity of the disease were evaluated using the Expanded Disability Status Scale and magnetic resonance imaging with gadolinium, respectively. IFN‑γ and IL‑6, ‑12 and ‑4 levels were higher in RR‑MS patients compared to controls (P=0.0009, 0.0114, 0.0297 and 0.0004, respectively). IL‑1 levels were higher in controls compared with RR‑MS patients. IL‑4 levels were higher in RR‑MS patients with mild disability compared to those with moderate and severe disability (P=0.0375). TNF‑α and IL‑10 levels were higher in RR‑MS patients with inactive disease compared with those with active disease. IL‑17 levels showed a trend towards being higher in RR‑MS patients with inactive disease compared to those with active disease (P=0.0631). Low TNF‑α and high IFN‑γ levels were independently associated with RR‑MS (P=0.0078 and 0.0056, respectively) and also with the activity of the disease (P=0.0348 and 0.0133, respectively). Results indicated that RR‑MS patients, even in the remission clinical phase, exhibit a complex system of inflammatory and anti‑inflammatory cytokines that may interact to modulate the progression and activity of the disease.

Type 1 immune response in progressive multiple sclerosis

The aim of the study was to evaluate the type-1 immune response by analyzing T-bet expression in circulating T and B cells in Primary Progressive (PP) and Secondary Progressive (SP) Multiple Sclerosis (MS) patients. We found higher percentages of circulating CD4+T-bet+ and CD8+T-bet+ T cells in SPMS and PPMS than in remitting-relapsing MS patients and controls. Moreover, in SPMS, we observed a positive correlation between the percentages of circulating CD4+T-bet+ or CD8+T-bet+ T cells and disease severity. The increased percentages of Th1 and Tc1 cells suggest that MS progressive forms, unlike RRMS, are characterized by a permanent peripheral type-1 immune activation.

Combined exercise training reduces IFN-γ and IL-17 levels in the plasma and the supernatant of peripheral blood mononuclear cells in women with multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disorder in which lymphocytic infiltration mediated mainly by pro-inflammatory cytokines. In this study, we examined the effect of combined exercise training on the levels of IFN-γ, IL-4 and IL-17 in the plasma and the supernatant of peripheral blood lymphocytes in women with multiple sclerosis. Expanded Disability Status Scale (EDSS), VO(2)max, muscle strength, and balance tests were obtained at baseline and post-treatment follow-up. Combined exercises training was designed for 24 sessions during 8 weeks. Each session was started with 5 min warm-up and was followed by 10 min stretch training, 20 min aerobic exercises and 20 min resistance-endurance training. The disability score was significantly decreased in test MS subjects after 8 weeks combined exercise training. Muscle strength and balance were increased significantly after the training program in test group. In this study, plasma, and peripheral blood mononuclear cell (PBMC) IL-17 and IFN-γ production was significantly decreased after 8 weeks combined training. Our findings suggest that combined training has useful anti-inflammatory effects by decrease in PBMC and plasma IL-17 production.

A role for interferon-beta in Guillain-Barré Syndrome?

Guillain-Barré syndrome (GBS) is an acute inflammatory demyelinating neuropathy that is associated with long-lasting morbidity and a substantial risk of mortality. The 2 reference treatments, plasma exchange and intravenous immunoglobulins (IVIg), do not change the functional prognosis for the most severely ill patients. The pathogenesis of GBS involves humoral and cellular immune dysfunctions that have only recently been characterised. Antibodies to nerve antigens may participate in complement activation, antibody-dependent macrophage cytotoxicity and reversible conduction failure. The cellular immune reaction is associated with increases in pro-inflammatory cytokines [such as tumour necrosis factor-alpha (TNFalpha)] and matrix metalloproteinases (MMPs; e.g. MMP-9), and a decrease in anti-inflammatory cytokines [such as transforming growth factor-beta1 (TGFbeta1)]. All the changes favour adhesion to and transmigration across the endothelium of immune cells, a key phenomenon associated with GBS. Recovery from GBS is characterised by the normalisation of these changes. Experimental allergic neuritis (EAN), the experimental model of GBS, has strikingly similar immunological characteristics. The usual treatment options for patients with GBS (plasma exchange and IVIg) mainly target the humoral component of the immune response. Interferon-beta (IFNbeta) is a cellular immunomodulator that inhibits antigen presentation and TNFalpha production and binding, and modulates macrophage properties. IFNbeta increases anti-inflammatory T cell functions and the production of anti-inflammatory cytokines, such as TGFbeta1. IFNbeta has important effects on leukodiapedesis, caused by modulating the expression of cell adhesion molecules and the MMP-9 proteinases. It has been used with success in EAN, in some patients with acute exacerbation of chronic inflammatory demyelinating polyneuropathy, and in 1 patient with GBS. The pathophysiology of patients with GBS, an understanding of IFNbeta properties and results of experimental studies support the investigation of IFNbeta in trials of patients with GBS.

Fetal BM-derived mesenchymal stem cells promote the expansion of human Th17 cells, but inhibit the production of Th1 cells

Th type 17 (Th17) cells have been identified as a proinflammatory T-cell subset. Here, we investigated the regulation of human Th17 cells by fetal BM-derived mesenchymal stem cells (FBM-MSC). We cocultured FBM-MSC with human PBMC or CD4(+) T cells from healthy donors. FBM-MSC significantly suppressed the proliferation of CD4(+) T cells stimulated by PHA and recombinant IL-2. Significantly higher levels of IL-17 were observed in FBM-MSC cocultured with either PBMC or CD4(+) T cells than that in PBMC cultured alone or CD4(+) T cells cultured alone. Flow cytometry analysis showed that the percentage of Th17 cells in coculture of FBM-MSC and CD4(+) T cells was significantly higher than that in CD4(+) T-cell cultured alone. FBM-MSC did not express IL-17 protein. Consistent with the augmentation of Th17 cells, significantly higher levels of IL-6 and IL-1 were observed in coculture of FBM-MSC and CD4(+) T cells than that in CD4(+) T-cell culture, while the levels of IL-23 were similar between FBM-MSC + PBMC coculture and PBMC alone, or FBM-MSC + CD4(+) T-cell and CD4(+) T-cell alone. The presence of FBM-MSC decreased the percentage of Th1 cells, but minimally affected the expansion of CD4(+)CD25(+) T cells. In conclusion, our data demonstrate for the first time that FBM-MSC promote the expansion of Th17 cells and decrease IFN-gamma-producing Th1 cells. These data suggest that IL-6 and IL-1, instead of IL-23, may be partly involved in the expansion of Th17 cells.

Cytokines in idiopathic inflammatory myopathies

Recent findings suggest cytokines as important key molecules in the pathogenic mechanisms of idiopathic inflammatory myopathies, myositis. In this review, we focus on cytokines with a potential role in disease mechanisms in myositis and present some general information on individual cytokines and an updated summary from the literature concerning cytokines in these disorders. The idiopathic inflammatory myopathies is a heterogeneous group of disorders clinically characterized by symmetric proximal muscle weakness and by certain defined histolopathological findings, including inflammatory infiltrates in muscle tissue. Other prominent findings in the target tissue of these patients are defined molecular changes of blood vessels and muscle fibers, including reformation to high endothelial venule (HEV)-like blood vessels and intensive MHC class I expression in muscle fibers. The predominant clinical symptoms of muscle weakness and decreased muscle endurance are shared by all subsets of inflammatory myopathies and indicate that some pathogenic mechanisms related to muscle function may be shared by the different disease groups. Studies on cytokine gene, RNA and protein expression in muscle tissue from patients with various forms of the disease also indicate similar profiles, despite different phenotypes of the inflammatory cells present in muscle tissue from the different subsets of myositis. There is a pronounced expression of various cytokines in muscle tissue, among which the proinflammatory cytokines TNF-alpha and IL-1 are most widely explored in the inflammatory myopathies, which has made them into potential therapeutic targets. The use of targeted cytokine therapy has been successful in several other chronic inflammatory diseases and although the exact role of cytokines in chronic idiopathic inflammatory myopathies remains to be delineated their potential role as targets for new therapies in this disorder will be discussed in this review.

Lymphocyte Subpopulations, Oxidative Burst and Apoptosis in Peripheral Blood Cells of Patients with Multiple Sclerosis–Effect of Interferon-β

At present, the most efficient therapeutical treatment of multiple sclerosis (MS) is achieved by IFN-beta. However, its in vivo effects remain incompletely understood. If applied parenterally, the hydrophobic IFN-beta acts primarily on blood cells with probable selectivity for functionally different lymphocyte subpopulations, monocytes and granulocytes. We have investigated the expression of the activation marker interleukin-2 receptor-alpha (CD25) on CD3+ T cells, CD19+ B cells, foetal-type gamma(delta)+CD3+ T cells and foetal-type CD5+CD19+ B cells of the peripheral blood. In addition, the oxidative burst activity and apoptosis have been determined in mononuclear and polymorphonuclear blood cells, respectively. The study accompanied a phase III trial with IFN-beta1b (BETAFERON, Schering). Two groups of MS patients with relapsing-remitting course of the disease have been investigated at 8 time points (days 0, 5, 15, 31, 60, 90, 180 and 270 after starting therapy): (1) verum group (n = 8) with application of 8 Mill. units IFN-beta1 b every other day, and (2) placebo group (n = 4) with application of placebo for 3 months and therapy as in (1) from day 90 onward. The main results were: (1) Activated T cells decreased until day 180 in the verum group and return thereafter to pre-treatment values, whereas in the placebo group the values remained relatively stable over the whole observation period. (2) Activated B cells increased between days 90 and 270 in both groups, i.e. after verum application in both groups. (3) Foetal-type B cells were more activated than total B and T cells with increase over time in both groups. (4) Foetal-type T cells exerted relatively stable intra-individual levels with generally low CD25 expression, but punctual CD25 peaks in both groups. (5) The spontaneous oxidative burst was higher in lymphocytes, more variable in monocytes and faster increasing in granulocytes in the verum group than in the placebo group. (6) Apoptosis of mononuclear cells and granulocytes showed similar variations in the verum and placebo groups with the exception of a selective increase over time of the proportion of granulocytes undergoing induced apoptosis in the verum group. It is concluded that IFN-beta has the following main effects on the immune system of MS patients: (1) the T cell immunity is systemically and reversibly suppressed, (2) the foetal-type lymphocytes, which are responsible for the first line of defence of infections, are stimulated in the long range, (3) the oxidative burst activity is increased in lymphocytes and granulocytes and instable in monocytes, and (4) the inducibility of apoptosis in granulocytes is increased. Re-examination of the altered blood cell parameters after long-term IFN-beta therapy is warranted.

The role of CD4 T cells in the pathogenesis of multiple sclerosis

T lymphocytes play a central role in the pathogenesis of multiple sclerosis (MS) (Zhang et al., 1992). Both CD4+ and CD8+ T cells have been demonstrated in MS lesions, with CD4+ T cells predominating in acute lesions and CD8+ T cells being observed more frequently in chronic lesions (Raine, 1994). Additionally, T cells are found in all four of the described histopathologic subtypes of MS (Lucchinetti et al., 2000). Activated myelin-reactive CD4+ T cells are present in the blood and cerebrospinal fluid (CSF) of MS patients; in contrast, only nonactivated myelin-reactive T cells are present in the blood of controls (Zhang et al., 1994). The success of several T-cell-targeted therapies in MS reinforces the importance of the role of the T cell in MS pathogenesis. Here, we outline basic concepts in CD4+ T-cell immunology and summarize the current understanding of the role of CD4+ T cells in the pathogenesis of MS.

CD8+ T cell activation correlates with disease activity in clinically isolated syndromes and is regulated by interferon-beta treatment

An increased percentage of blood CD8+ T cells from patients with clinically isolated syndromes (CIS) suggestive of multiple sclerosis (MS) was found to express CD26 and CD69. The percentage of CD26 or CD69 positive CD8+ T cells was higher in patients with MRI evidence of disease dissemination in space or with active MRI lesions than in the remaining patients. Treatment of MS with interferon (IFN)-beta resulted in a decrease in the percentage of CD26 and CD71 positive CD8+ T cells and an increase in the percentage of CD8+ T cells that expressed interleukin (IL)-10 and IL-13. CD8+ T cell activation in MS may be linked to disease activity already at disease onset, and is regulated by treatment with IFN-beta.

Association between peripheral IFN-γ producing CD8+ T-cells and disability score in relapsing-remitting multiple sclerosis

A large body of evidence supports the involvement of the immune system in the pathogenesis of multiple sclerosis (MS). Nevertheless, how the peripheral T-cells phenotypes are associated with factors such as the disability score, the effects of immunomodulatory treatments, or the activation period is poorly understood. In this study, we have centered our attention on the presence of IFN-gamma and IL-4 producing CD4+ and CD8+ T-cells in the peripheral blood of 58 relapsing-remitting MS (RRMS) patients, 48 that were stable and 10 who were in relapse period, and 30 healthy controls (HC). Our results support the existence of an independent association between the percentage of IFN-gamma producing CD8+ lymphocytes and the increased levels of disability score. Furthermore, the number of IFN-gamma producing CD8+ lymphocytes and the disability score were not correlated in patients treated with interferon-beta, evidence of its possible benefits in combating a pro-inflammatory profile. Finally, we compared the T-cell populations in RRMS patients in the stable or active period, and we found a significant decrease of IFN-gamma producing CD4+ lymphocytes in active patients. In conclusion our study supports the hypothesis that different peripheral blood T-cell phenotypes are associated with disability score or active period of the disease.

Role of Magnetic Resonance Imaging and Immunotherapy in Treating Multiple Sclerosis

Significant advances in magnetic resonance imaging (MRI) technology and treatment of multiple sclerosis (MS) have been made during the past decade. These advances have revealed evidence of profound heterogeneity in MS. There is a clear need to revisit the key issues in MS pathogenesis and treatment strategies, taking new data into consideration. This paper provides an overview of recent progress in MS research, including (a) a review of clinical, pathologic, and immunologic aspects of MS, (b) a discussion of the mechanism of action of currently available disease-modifying drugs for MS, (c) an account of the role of MRI in clinical management and clinical trials in MS, and (d) an overview of some emerging treatments for MS.

Immunomonitoring measures in relapsing-remitting multiple sclerosis

Forty-five patients with relapsing-remitting multiple sclerosis (MS) were examined to determine intracellular cytokine profiles and the surface phenotype of circulating lymphocytes during active, recovery, and stable stages. Active stage patients were characterized by decreases in CD4(+)IL-4(+) Th2 as well as CD4(+)IFN-gamma(+) Th1 cells, when compared with stable stage patients and 16 healthy controls. CCR4(+) Th2 cells were persistently decreased at every MS stage as compared to the controls. CD4(+)CD29(+) and CD4(+)CXCR3(+) cells were closely correlated with IFN-gamma-producing cells. These findings suggest that simultaneous flow cytometry for these two types of measurements can provide information concerning current immune status in MS.

High prevalence of autoreactive, neuroantigen-specific CD8+ T cells in multiple sclerosis revealed by novel flow cytometric assay

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system (CNS) with features suggestive of T-cell-mediated pathology. Most prior reports have focused on CD4(+) T cells with the underlying assumption that MS is predominantly a CD4(+) T helper 1 (Th1)-mediated disease. In this report, we used a novel flow cytometric approach to evaluate autoreactive T-cell responses against a large variety of neuroantigenic targets. We found that both CD4(+) and CD8(+) T cells targeted against several CNS autoantigens were widely prevalent in patients with MS and healthy individuals. Whereas the distribution of CD4(+) responses was similar in different groups, patients with relapsing-remitting MS showed a higher proportion of CNS-specific CD8(+) responses. Autoreactive CD4(+) T cells from patients with MS exhibited a more differentiated Th1 phenotype compared with healthy subjects. Similarly, CNS-specific CD8(+) T-cell responses from patients with MS were functionally distinct from those in healthy individuals. Collectively, these studies reveal the high prevalence of class I-restricted autoreactive CD8(+) T-cell responses in MS that has been underappreciated thus far. The results emphasize the need to evaluate both CD4(+) and CD8(+) T-cell responses in MS and to make both subsets a consideration in the development of novel therapeutic strategies.

Circulating lymphocyte subsets linked to intracellular cytokine profiles in normal humans

To determine whether there is an association between intracellular cytokine profiles and the expression of surface antigens, we performed a simultaneous flow cytometric analysis of these laboratory parameters in 11 healthy volunteers. Peripheral blood lymphocytes were double-stained for CD4 or CD8, as well as CD11a, CD25, CD26, CD29 and CD45RA or the chemokine receptors CCR3, CCR4, CCR5 or CXCR3. Portions of the cell samples were cultured for 4 h in the presence of 1 microm monensin and 20 microg/ml brefeldin A with or without stimulation by phorbol myristate acetate plus ionomycin for the detection of intracellular interferon-gamma (IFN-gamma), interleukin-2 (IL-2), tumour necrosis factor (TNF)-alpha, and IL-4. As a result, CD4+CD29high helper inducer T cells were closely associated with IFN-gamma and TNF-alpha producing CD4+ cells, while CD4+CXCR3+ cells showed a negative correlation with IL-4-producing cells, suggesting that both of these CD4+ subsets consist mainly of Th1 cells. In contrast, CD4+CD45RA+ cells were correlated inversely with IFN-gamma and TNF-alpha-producing cells, and CD8+CD11ahigh killer effector and total CCR5+ cells showed an inverse correlation with IL-2 producing cells, suggesting an immunoregulatory role for these three subsets in non-pathological conditions. Therefore, monitoring of lymphocyte subsets that express functional surface antigens could provide additional information concerning immune deviation, as assessed by the production of Th1/Th2 type cytokines. Further, this type of combined study may provide clues for the pathogenesis of immune-mediated disorders.

IFN-beta1a (Rebif) modifies the expression of microfilament-associated cell-cell contacts in C6 glioma cells

Multiple sclerosis (MS) is a chronic inflammatory disease characterized by multifocal demyelination and axonal damage in the central nervous system (CNS). The disruption of the endothelial blood-brain barrier (BBB) with consecutive transmigration of inflammatory cells into the brain parenchyma is of critical importance in the pathogenesis of MS. The integrity of the BBB and the adjacent network of glial cells partially depends on the assembly of intercellular contacts between astrocytes. We demonstrate that recombinant interferon-gamma (rIFN-gamma), a proinflammatory cytokine critically involved in the disruption of the BBB, downregulates the expression of the cell adhesion molecules N-cadherin and vinculin in astrocytic C6 cells using Western blot and immunofluorescence microscopy. By contrast, IFN-beta1a, an established treatment for relapsing-remitting MS, increases the expression of N-cadherin and vinculin and partly inhibits the downregulation of these adhesion molecules by phytohemagglutinin (PHA)-stimulated IFN-gamma-secreting human T lymphocytes in coculture experiments. In summary, we demonstrate that IFN-beta1a modifies the assembly of N-cadherin- and vinculin-mediated intercellular contacts between astrocytic C6 cells in vitro. This effect may also contribute to the therapeutic action of IFN-beta1a in MS.

A comparison of the mechanisms of action of interferon beta and glatiramer acetate in the treatment of multiple sclerosis

BACKGROUND

The development of immunomodulatory agents has represented a major advance in the treatment of multiple sclerosis (MS). To date, immunomodulatory agents approved for the treatment of relapsing MS in the United States include 3 forms of recombinant interferon (IFN) beta (2 formulations of IFN beta-1a and 1 of IFN beta-1b) and synthetic glatiramer acetate (GA). Recognition of how these agents work to regulate the immune system may lead to a better understanding of disease mechanisms, as well as to development of more effective therapies or combinations of therapy.

OBJECTIVE

This article reviews the potential mechanisms of action of IFN beta products and GA in the context of their regulatory effects on autoimmune components that may be of importance in MS.

METHODS

MEDLINE and Current Contents/Clinical Medicine were searched for articles published in English from 1993 to the present using the search terms interferon beta, glatiramer acetate, and multiple sclerosis.

RESULTS

IFN beta products affect the disease process in MS through multiple potential mechanisms of action, including antiviral, antiproliferative, and anti-inflammatory effects. The mechanisms of action of GA are less clear, but may involve immune regulation induced by a gradual shift of T-cell phenotype from proinflammatory (type 1 T-helper cells) to anti-inflammatory (type 2 T-helper cells) and interference with antigen presentation.

CONCLUSION

Understanding the mechanisms of action of IFN beta products and GA provides important insights into the disease processes involved in MS.

Intracellular interferon-gamma in circulating and marrow T cells detected by flow cytometry and the response to immunosuppressive therapy in patients with aplastic anemia

Immunosuppressive therapy leads to meaningful hematologic improvement in most patients with aplastic anemia (AA). Failure to respond and a later relapse could be due to deficient numbers of hematopoietic stem cells, inadequate treatment of the immune process, or a nonimmunologic etiology. Interferon-gamma (IFN-gamma) has been implicated in the pathophysiology of hematopoietic failure in AA. On the basis of previous findings showing overexpression of IFN-gamma in bone marrow (BM) and peripheral blood (PB) in this disease, we hypothesized that quantitation of IFN-gamma might be applied to predict and monitor responses to immunosuppressive therapy. We measured expression of IFN-gamma in lymphocytes obtained from 123 AA patients, using intracellular 2-color fluorescent staining and flow cytometry. Of 70 patients with severe AA, 36 (51%) demonstrated increased IFN-gamma in circulating T cells. IFN-gamma was detected in only 4 of 53 patients who had recovered from AA. IFN-gamma was not found in PB lymphocytes of patients with other hematologic diseases and heavy transfusion burdens or in healthy volunteers. Among 62 AA patients who were assessed before first treatment with immunosuppressive drugs, 27 of 28 (96%) with circulating IFN-gamma-containing T cells subsequently responded to therapy; in contrast, only 11 of 34 (32%) patients whose PB lacked IFN-gamma lymphocytes improved to transfusion independence. IFN-gamma-containing lymphocytes declined following treatment in all cases. Of 17 patients assessed during relapse, IFN-gamma was present in T cells prior to the blood count decline in 13, and 12 responded to reinstitution of immunosuppressive drugs. Of 30 BMs tested prior to first treatment, 20, all in responding patients, were positive for IFN-gamma, whereas the negative tests were obtained in 10 nonresponding patients. IFN-gamma is increased in the PB lymphocytes of many patients with AA, and these cells decline with therapy. The presence of intracellular IFN-gamma may predict response to immunosuppressive treatment and also the onset of relapse.

Identification of new therapeutic targets for prevention of CNS inflammation

Multiple sclerosis (MS) is a disease of complex pathologies, which involves infiltration by CD4(+) and CD8(+) T cells of and response within the central nervous system. Expression in the CNS of cytokines, reactive nitrogen species and costimulator molecules have all been described in MS. Notably, the cytokines IFN-gamma and TNF are strongly expressed. Microglial cells in the CNS express costimulator molecules and it is assumed that they play a role in directing or inducing the T cell response. Transgenic experiments have tested the effects of overexpression of these molecules in mice and have shown that TNF has multiple effects in the CNS. These range from pro-inflammatory effects of soluble TNF signalling through one of its receptors TNF-RI, to protective/regenerative effects of membrane-associated TNF signalling through the other receptor, TNF-RII. Although IFN-gamma induces nitric oxide production via the enzyme inducible nitric oxide synthase, which is immunosuppressive, IFN-gamma is predominantly pro-inflammatory. In CNS disease in mice that involves CD8(+) T cells, IFN-gamma blockade is protective. Finally, microglial expression of the costimulator ligand B7.2 induces demyelinating pathology. Animal experiments therefore point to IFN-gamma and costimulatory microglia as logical targets of therapy for MS. IFN-gamma represents a more accessible target and should therefore be pursued at the earliest opportunity.

A partially humanized monoclonal antibody to human IFN-gamma inhibits cytokine effects both in vitro and in vivo

The mouse monoclonal antibody (MoAb) IGMB17 (muIGMB17) is a high-affinity antibody- neutralizing human interferon (IFN)-gamma and, accordingly, is a potential therapeutic agent for patients suffering from various diseases in which the cytokine is abnormally expressed. The clinical usefulness of mouse antibodies is limited, however, owing to their immunogenicity in humans. MuIGMB17 antibody was partially humanized by engrafting a small portion of mouse light chain (LC) in a human framework and by engineering its heavy chain (HC) in a chimeric version. The engineered IGMB17 (huIGMB17) was able to replicate a range of functional properties of the original muIGMB17, namely, specific binding to IFN-gamma, inhibition of histocompatibility complex (HLA-DR) expression in response to IFN-gamma induction, reversion of IFN-gamma antiproliferative activity on sensitive cell lines. We have hypothesized that as huIGMB17 was able to block IFN-gamma binding to its receptor as well as its murine counterpart, huIGMB17 could neutralize all cytokine activity, also in vivo. Indeed huIGMB17 was capable of interfering with delayed-type hypersensitivity reaction in humans, thus demonstrating its effectiveness in neutralizing IFN-gamma-mediated reactions in vivo.

Tc1/Tc2 and Th1/Th2 balance in Asian and Western types of multiple sclerosis, HTLV-I-associated myelopathy/tropical spastic paraparesis and hyperIgEaemic myelitis

CD8+ T cells, like CD4+ T cells, can differentiate into at least two subsets with distinct cytokine patterns: Tc1 cells produce Th1-like cytokines and Tc2 cells produce Th2-like cytokines. To clarify the immunopathological roles of Tc1 and Tc2 cells in central nervous system (CNS) inflammation, we examined intracellular cytokines in CD8+ and CD4+ T cells by flow cytometry and analyzed the Tc1/Tc2 balance as well as the Th1/Th2 balance in 80 patients with various CNS inflammatory diseases, including 20 with optico-spinal multiple sclerosis (OS-MS), 21 with conventional MS (C-MS), 22 with human T-lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and 17 with hyperIgEaemic myelitis. Twenty-two healthy subjects were also examined as controls. Patients with OS-MS showed a significantly higher percentage of INF-gamma+IL-4- CD8+ T cells as well as CD4+ T cells and a significantly higher intracellular interferon-gamma (IFN-gamma)/interleukin-4 (IL-4) ratio both in CD8+ and CD4+ T cells throughout the relapse and remission phases than the healthy controls. Furthermore, the patients with OS-MS showed a significantly lower percentage of INF-gamma-IL-4+ CD4+ T cells as well as CD8+ T cells during the relapse phase than the healthy controls. On the other hand, the patients with C-MS showed a significantly higher percentage of IFN-gamma-IL-4+ CD8+ T cells in addition to more IFN-gamma+IL-4- CD4+ T cells during the relapse phase than the healthy controls. The HAM/TSP patients showed a significantly higher percentage of INF-gamma+IL-4- CD8+ T cells and a significantly higher intracellular IFN-gamma/IL-4 ratio in CD8+ T cells than the healthy controls. In contrast, in hyperIgEaemic myelitis, in addition to a significantly lower intracellular IFN-gamma/IL-4 ratio in CD4+ T cells, a tendency toward a lower intracellular IFN-gamma/IL-4 ratio in CD8+ T cells in comparison to the healthy controls was observed. These results clarified for the first time the distinct Tc1/Tc2 balance in each disease condition as follows: Tc1 cell response is predominant in OS-MS and HAM/TSP, while Tc2 cell response is predominant in hyperIgEaemic myelitis and at relapse phase of C-MS. Furthermore, our results suggest that CD8+ T cells play an adjunctive role in disease induction and the clinical course of MS.

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

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

Intracellular cytokine profile in T-cell subsets of multiple sclerosis patients: different features in primary progressive disease

OBJECTIVE

To evaluate the expression of cytokines in both CD4+ and CD8+ T cells derived from peripheral blood of untreated multiple sclerosis (MS) patients with either relapsing-remitting (RR), secondary progressive (SP) or primary progressive (PP) MS and healthy controls (HC).

BACKGROUND

MS is an immune-mediated disease and cytokines hove been hypothesized to contribute significantly to disease progression. Compared to the relapse-onset (RR, SP) form of the disease, PPMS patients have different clinical, immunological and pathological features. Surprisingly, the ability of their circulating T cells to produce immunoregulatory cytokines has not been extensively studied so far.

METHODS

Seventy-two MS patients (24 RR, 26 SP, 22 PP) and 34 HC were studied. Stimulated peripheral blood derived CD4+ and CD8+ T MS patients express significantly more CD4+ and CD8+ T cells were analyzed for IFN-gamma, IL-2, TNF-alpha, IL-4, IL-10 and IL-13 production.

RESULTS

cells producing IFN-gamma compared to HC. Compared to the other forms of the disease, PPMS patients display a significant decrease in CD4+ T cells producing IL-2, IL-13 and TNF-alpha and a significant increase in CD8+ T cells producing IL-4 and IL-10.

CONCLUSIONS

The data presented here demonstrate that patients with PPMS express less pro- and more anti-inflammatory cytokine producing T cells compared to the relapse-onset form of the disease, confirming the view on PPMS as a distinct disease entity.

Similar pro- and anti-inflammatory cytokine production in the different clinical forms of multiple sclerosis

Cytokines play an important role in the initiation and maintenance of the inflammatory reaction in multiple sclerosis, a chronic inflammatory demyelinating disease of the central nervous system. Magnetic resonance imaging 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 understanding better the relative role of pro-inflammatory and/or anti-inflammatory cytokines in primary progressive multiple sclerosis in comparison to relapsing forms, we analysed in 65 patients (24 primary progressive, 20 relapsing-remitting and 21 secondary progressive) and 29 healthy controls, the production of cytokines (IFN-gamma, TNF-alpha, IL-6, IL-10 and IL-12) by peripheral blood mononuclear cells after in vitro stimulation. We found a similar percentage of cytokines producing cells between healthy controls and the different clinical forms of multiple sclerosis patients.

Intra-CNS activation by antigen-specific T lymphocytes in experimental autoimmune encephalomyelitis

Identification and quantitation of autoreactive T lymphocytes is crucial in order to understand the pathogenesis of autoimmune diseases. We used flow cytometry to analyze autoantigen-specific T cellular responses in the well characterized rat experimental autoimmune encephalomyelitis (EAE) model. Cells isolated from both the central nervous system (CNS) tissue and peripheral lymph nodes were analyzed directly ex vivo or after short term in vitro culture with specific autoantigen. CNS infiltrating T lymphocytes displaying an interferon-gamma response to selected encephalitogenic myelin protein epitopes were measured kinetically during an individual disease episode and also between relapses in a chronic rat EAE model. One of the EAE models used displays a restriction towards TCRBV8S2 chain usage by the encephalitogenic T cells. In this model, in vitro production of intracellular interferon-gamma was selectively detected within this T cell subset derived from both the CNS and peripheral lymph nodes. Furthermore, antigen-specific cells infiltrating the CNS in this model produced several-fold higher amounts of interferon-gamma upon antigen stimulation and displayed a significantly increased in vivo proliferation compared with peripheral lymphocytes. These data thus directly demonstrates that T cells stimulated by a specific autoantigen in the periphery primarily acquire effector functions in the cellular environment of the target organ of the autoantigen.

Interferon-beta treatment in multiple sclerosis patients decreases the number of circulating T cells producing interferon-gamma and interleukin-4

Systemic administration of interferon (IFN)-beta has been recently approved for the treatment of relapsing-remitting multiple sclerosis (RRMS). The immunological mechanism by which IFN-beta ameliorates MS is still partially unknown. We measured the number of blood circulating CD4(+), CD4(-), CD8(+), and CD8(-) T cells secreting IFN-gamma and IL-4 in 26 RRMS patients followed for up to 9 months of an alternate day s.c. treatment with 8x16 IU of IFN-beta1b. Compared to pre-treatment values, a significant (P<0.05) reduction of CD4(+), CD4(-), CD8(+) and CD8(-) cells producing IFN-gamma and of CD4(+) and CD4(-) cells producing IL-4 was observed in MS patients. The IFN-beta-associated effect was evident soon after the beginning of the treatment and persisted for the entire follow-up period. We did not observe any effect of IFN-beta treatment on the percentage of IL-4-producing CD8(+) and CD8(-) cells nor in that of natural killer (NK) cells producing IFN-gamma. Our results show that IFN-beta treatment in MS patients induces a profound and persistent down-regulation of the number of circulating T cells secreting IFN-gamma and IL-4 thus suggesting a broader rather than a specific immunomodulatory effect of IFN-beta in MS.