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

Profiling of Canonical and Non-Traditional Cytokine Levels in Interferon-β-Treated Relapsing-Remitting-Multiple Sclerosis Patients

Background

Multiple sclerosis (MS) is a chronic, progressive autoimmune disease of the central nervous system in which inflammation plays a key role in the induction, development, and progression. Most of the MS patients present with relapsing–remitting (RR) form, characterized by flare-ups followed by periods of recovery. Many inflammatory and anti-inflammatory cytokines have been proposed as backers in MS pathogenesis, and the balance between these differing cytokines can regulate MS severity. Interferon (IFN)-β, a current disease-modifying therapy for MS, has demonstrated beneficial effects in reducing disease severity in MS patients. However, its immunoregulatory and anti-inflammatory actions in MS are not wholly understood. The aim of the study was to define, in clinically stable patients with RR-MS, the serum concentration of several cytokines, canonical or not, and their modulation by IFN-β therapy.

Methods

Relapsing–remitting-MS patients were enrolled and diagnosed according to revised Mc Donald Diagnostic Criteria. A set of cytokines [including non-canonical neurotransmitter acetylcholine (ACh) and adipokines] and B-cell differentiation molecules, as potential biomarkers, were evaluated in 30 non-treated RR-MS patients compared to 30 IFN-β-treated MS patients and 30 age, gender, and body mass index-matched healthy controls (HC).

Results

Naïve MS patients showed significantly higher levels of interleukin (IL)-1β, IL-12/IL-23p40, IL-18, high-mobility group box protein-1, and IL-18 binding protein (IL-18BP) than MS-treated patients (p < 0.001 for all) and HC (p < 0.01). IFN-β therapy has significantly downmodulated IL-1β, IL-12/IL-23p40, IL-18 to normal levels (p < 0.001), whereas it has decreased IL-18BP (p < 0.001). ACh was significantly higher in the IFN-β-treated than HC and non-treated MS patients (p < 0.001). No significant differences were observed either in adipokines concentration or in B-cell-associated molecules among the three study groups.

Conclusion

Although more experimental evidence are required, we speculate that the efficacy of treatment of MS with IFN-β is mediated, at least in part, by its ability to work on several levels to slow down the disease progression. Proposed actions include the modulation of IL-1–inflammasome axis and modulation of ACh, B-cell activating factor/a proliferation-inducing ligand system, and several adipokines.

Interferon-β suppresses murine Th1 cell function in the absence of antigen-presenting cells

Interferon (IFN)-β is a front-line therapy for the treatment of the relapsing-remitting form of multiple sclerosis. However, its immunosuppressive mechanism of function remains incompletely understood. While it has been proposed that IFN-β suppresses the function of inflammatory myelin antigen-reactive T cells by promoting the release of immunomodulatory cytokines such as IL-27 from antigen-presenting cells (APCs), its direct effects on inflammatory CD4⁺ Th1 cells are less clear. Here, we establish that IFN-β inhibits mouse IFN-γ⁺ Th1 cell function in the absence of APCs. CD4⁺ T cells express the type I interferon receptor, and IFN-β can suppress Th1 cell proliferation under APC-free stimulation conditions. IFN-β-treated myelin antigen-specific Th1 cells are impaired in their ability to induce severe experimental autoimmune encephalomyelitis (EAE) upon transfer to lymphocyte-deficient Rag1^-/- mice. Polarized Th1 cells downregulate IFN-γ and IL-2, and upregulate the negative regulatory receptor Tim-3, when treated with IFN-β in the absence of APCs. Further, IFN-β treatment of Th1 cells upregulates phosphorylation of Stat1, and downregulates phosphorylation of Stat4. Our data indicate that IFN-γ-producing Th1 cells are directly responsive to IFN-β and point to a novel mechanism of IFN-β-mediated T cell suppression that is independent of APC-derived signals.

A comparative study of experimental mouse models of central nervous system demyelination

Several mouse models of multiple sclerosis (MS) are now available. We have established a mouse model, in which ocular infection with a recombinant HSV-1 that expresses murine IL-2 constitutively (HSV-IL-2) causes CNS demyelination in different strains of mice. This model differs from most other models in that it represents a mixture of viral and immune triggers. In the present study, we directly compared MOG_35–55, MBP_35–47, and PLP_190–209 models of EAE with our HSV-IL-2-induced MS model. Mice with HSV-IL-2-induced and MOG-induced demyelinating diseases demonstrated a similar pattern and distribution of demyelination in their brain, spinal cord, and optic nerves. In contrast, no demyelination was detected in the optic nerves of MBP- and PLP-injected mice. IFN-β injections significantly reduced demyelination in brains of all groups, in the spinal cords of the MOG and MBP groups, and completely blocked it in the spinal cords of the PLP and HSV-IL-2 groups as well as in optic nerves of MOG and HSV-IL-2 groups. In contrast to IFN-β treatment, IL-12p70 protected the HSV-IL-2 group from demyelination, while IL-4 was not effective at all in preventing demyelination. MOG-injected mice showed clinical signs of paralysis and disease-related mortality whereas mice in the other treatment groups did not. Collectively, the results indicate that the HSV-IL-2 model and the MOG model complement each other and, together, provide unique insights into the heterogeneity of human MS.

CD80+ and CD86+ B cells as biomarkers and possible therapeutic targets in HTLV-1 associated myelopathy/tropical spastic paraparesis and multiple sclerosis

Background

Human T-cell lymphotropic virus (HTLV-1) is the causative agent of the incapacitating, neuroinflammatory disease HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Currently, there are no disease-modifying therapies with long-term clinical benefits or validated biomarkers for clinical follow-up in HAM/TSP. Although CD80 and CD86 costimulatory molecules play prominent roles in immune regulation and reflect disease status in multiple sclerosis (MS), data in HAM/TSP are lacking.

Methods

Using flow cytometry, we quantified ex vivo and in vitro expression of CD80 and CD86 in PBMCs of healthy controls, HTLV-1-infected individuals with and without HAM/TSP, and MS patients. We hypothesized ex vivo CD80 and CD86 expressions and their in vitro regulation by interferon (IFN)-α/β mirror similarities between HAM/TSP and MS and hence might reveal clinically useful biomarkers in HAM/TSP.

Results

Ex vivo expression of CD80 and CD86 in T and B cells increased in all HTLV-1 infected individuals, but with a selective defect for B cell CD86 upregulation in HAM/TSP. Despite decreased total B cells with increasing disease duration (p = 0.0003, r = −0.72), CD80⁺ B cells positively correlated with disease severity (p = 0.0017, r = 0.69) in HAM/TSP. B cell CD80 expression was higher in women with HAM/TSP, underscoring that immune markers can reflect the female predominance observed in most autoimmune diseases. In contrast to MS patients, CD80⁺ (p = 0.0001) and CD86⁺ (p = 0.0054) lymphocytes expanded upon in vitro culture in HAM/TSP patients. The expansion of CD80⁺ and CD86⁺ T cells but not B cells was associated with increased proliferation in HTLV-1 infection. In vitro treatment with IFN-β but not IFN-α resulted in a pronounced increase of B cell CD86 expression in healthy controls, as well as in patients with neuroinflammatory disease (HAM/TSP and MS), similar to in vivo treatment in MS.

Conclusions

We propose two novel biomarkers, ex vivo CD80⁺ B cells positively correlating to disease severity and CD86⁺ B cells preferentially induced by IFN-β, which restores defective upregulation in HAM/TSP. This study suggests a role for B cells in HAM/TSP pathogenesis and opens avenues to B cell targeting (with proven clinical benefit in MS) in HAM/TSP but also CD80-directed immunotherapy, unprecedented in both HAM/TSP and MS.

High-dose cyclophosphamide for moderate to severe refractory multiple sclerosis: 2-year follow-up (investigational new drug No. 65863)

High-dose cyclophosphamide (HDC) is a chemotherapy treatment designed to eradicate autoreative B- and T-cells responsible for lymphocyte-mediated autoimmune illness while sparing the pluripotent blood stem cell of any ill effects. Multiple sclerosis (MS) is the most common inflammatory and demyelinating immune-mediated disorder of the central nervous system in young adults. Patients with moderate to severe, refractory MS, defined as an Expanded Disability Status Scale (EDSS) score of 3.5 or higher after two or more Food and Drug Administration-approved disease-modifying agents, received 200 mg/kg of cyclophosphamide over 4 days. For the next 2 years, quarterly EDSS score evaluations and biannual brain magnetic resonance imaging and neuro-ophthalmologic evaluations were obtained. Fifteen patients were evaluated for clinical response. During follow-up, one patient increased their baseline EDSS score by 1.0. EDSS score stability of decrease was realized in five of seven (71%) patients with relapsing-remitting MS and six of eight (75%) patients with secondary progressive MS. Four patients required additional immunomodulatory treatment after treatment. Treatment response was seen regardless of the baseline presence or absence of contrast lesion activity. HDC can effectively decrease symptoms, stop disease progression, and allow for disability regression in relapsing-remitting MS and secondary progressive MS patients. The most appropriate candidates for HDC, its duration of benefit, and the potential need for prophylactic preventative immune manipulation after HDC all require further investigation.

IFN-β mediates suppression of IL-12p40 in human dendritic cells following infection with virulent Francisella tularensis

Active suppression of inflammation is a strategy used by many viral and bacterial pathogens, including virulent strains of the bacterium Francisella tularensis, to enable colonization and infection in susceptible hosts. In this study, we demonstrated that virulent F. tularensis strain SchuS4 selectively inhibits production of IL-12p40 in primary human cells via induction of IFN-β. In contrast to the attenuated live vaccine strain, infection of human dendritic cells with virulent SchuS4 failed to induce production of many cytokines associated with inflammation (e.g., TNF-α and IL-12p40). Furthermore, SchuS4 actively suppressed secretion of these cytokines. Assessment of changes in the expression of host genes associated with suppression of inflammatory responses revealed that SchuS4, but not live vaccine strain, induced IFN-β following infection of human dendritic cells. Phagocytosis of SchuS4 and endosomal acidification were required for induction of IFN-β. Further, using a defined mutant of SchuS4, we demonstrated that the presence of bacteria in the cytosol was required, but not sufficient, for induction of IFN-β. Surprisingly, unlike previous reports, induction of IFN-β by F. tularensis was not required for activation of the inflammasome, was not associated with exacerbation of inflammatory responses, and did not control SchuS4 replication when added exogenously. Rather, IFN-β selectively suppressed the ability of SchuS4-infected dendritic cells to produce IL-12p40. Together, these data demonstrated a novel mechanism by which virulent bacteria, in contrast to attenuated strains, modulate human cells to cause disease.

Use of cytokine immunotherapy to block CNS demyelination induced by a recombinant HSV-1 expressing IL-2

We previously have described a model of multiple sclerosis (MS) in which constitutive expression of murine interleukin (IL)-2 by herpes simplex virus type 1 (HSV-1) (HSV-IL-2) causes central nervous system (CNS) demyelination in different strains of mice. In the current study, we investigated whether this HSV-IL-2-induced demyelination can be blocked using recombinant viruses expressing different cytokines or by injection of plasmid DNA. We have found that coinfection of HSV-IL-2-infected mice with recombinant viruses expressing IL-12p35, IL-12p40 or IL-12p35+IL-12p40 did not block the CNS demyelination, and that coinfection with a recombinant virus expressing interferon (IFN)-γ exacerbated it. In contrast, coinfection with a recombinant virus expressing IL-4 reduced demyelination, whereas coinfection of HSV-IL-2-infected mice with a recombinant HSV-1 expressing the IL-12 heterodimer (HSV-IL-12p70) blocked the CNS demyelination in a dose-dependent manner. Similarly, injection of IL-12p70 DNA blocked HSV-IL-2-induced CNS demyelination in a dose-dependent manner and injection of IL-35 DNA significantly reduced CNS demyelination. Injection of mice with IL-12p35 DNA, IL-12p40 DNA, IL-12p35+IL-12p40 DNA or IL-23 DNA did not have any effect on HSV-IL-2-induced demyelination, whereas injection of IL-27 DNA increased the severity of the CNS demyelination in the HSV-IL-2-infected mice. This study demonstrates for the first time that IL-12p70 can block HSV-IL-2-induced CNS demyelination and that IL-35 can also reduce this demyelination, whereas IFN-γ and IL-27 exacerbated the demyelination in the CNS of the HSV-IL-2-infected mice. Our results suggest a potential role for IL-12p70 and IL-35 signaling in the inhibition of HSV-IL-2-induced immunopathology by preventing development of autoaggressive T cells.

IL-2 suppression of IL-12p70 by a recombinant HSV-1 expressing IL-2 induces T-cell auto-reactivity and CNS demyelination

To evaluate the role of cellular infiltrates in CNS demyelination in immunocompetent mice, we have used a model of multiple sclerosis (MS) in which different strains of mice are infected with a recombinant HSV-1 expressing IL-2. Histologic examination of the mice infected with HSV-IL-2 demonstrates that natural killer cells, dendritic cells, B cells, and CD25 (IL-2rα) do not play any role in the HSV-IL-2-induced demyelination. T cell depletion, T cell knockout and T cell adoptive transfer experiments suggest that both CD8⁺ and CD4⁺ T cells contribute to HSV-IL-2-induced CNS demyelination with CD8⁺ T cells being the primary inducers. In the adoptive transfer studies, all of the transferred T cells irrespective of their CD25 status at the time of transfer were positive for expression of FoxP3 and depletion of FoxP3 blocked CNS demyelination by HSV-IL-2. The expression levels of IL-12p35 relative to IL-12p40 differed in BM-derived macrophages infected with HSV-IL-2 from those infected with wild-type HSV-1. HSV-IL-2-induced demyelination was blocked by injecting HSV-IL-2-infected mice with IL-12p70 DNA. This study demonstrates that suppression of the IL-12p70 function of macrophages by IL-2 causes T cells to become auto-aggressive. Interruption of this immunoregulatory axis results in demyelination of the optic nerve, the spinal cord and the brain by autoreactive T cells in the HSV-IL-2 mouse model of MS.

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.

Interleukin-10 and interleukin-12 modulation in patients with relapsing-remitting multiple sclerosis on therapy with interferon-beta 1a: differences in responders and non responders

We examined the effects of interferon (IFN)beta-1a on interleukin (IL)-12p70 and IL-10 secretion in 27 Relapsing Remitting Multiple Sclerosis (RRMS) patients, divided in responders and non-responders. In responders, IFNbeta-1a does not change the IL-12p70 concentrations, but it leads to a remarkable increase in the IL-10 production. Besides, a high IL-10/IL-12 ratio is demonstrated during the first six months of therapy. In non-responders, there were not significant alterations in the cytokine profile. We suggest that IFNbeta-1a effect in RRMS patients could be explained by its modifying effect on cytokine pattern. Moreover, we propose a possible role of IL-10/IL-12 ratio as a serum marker predictive of favorable clinical course.

CD40/CD40L signaling and its implication in health and disease

CD40, a transmembrane receptor of the tumor necrosis factor gene superfamily is expressed on a variety of cells, such as monocytes, B-cells, antigen presenting cells, endothelial, smooth muscle cells, and fibroblasts. The interaction between CD40 and CD40 ligand (CD40L) enhances the expression of cytokines, chemokines, matrix metalloproteinases, growth factors, and adhesion molecules, mainly through the stimulation of nuclear factor kappa B. The aim of this review is to summarize the molecular and cellular characteristics of CD40 and CD40L, the mechanisms that regulate their expression, the cellular responses they stimulate and finally their implication in the pathophysiology of inflammatory and autoimmune diseases.

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.

Back to the future for multiple sclerosis therapy: focus on current and emerging disease-modifying therapeutic strategies

The last decade has seen numerous advances in the treatment of multiple sclerosis with six immunotherapeutic agents licensed for use. Although these therapeutic agents have powerful effects upon the inflammatory phase of disease, they have limitations in treating the progression of disability and in their safety profile. This review focuses on our current understanding of first- and second-line treatments for multiple sclerosis, including combination therapies, and also discusses the most promising novel therapeutic strategies on the horizon. Such agents include orally administered immunosuppressive drugs, monoclonal antibodies, antigen-specific tolerance, and neural protection and repair strategies. The challenge ahead lies in the delivery of potent drugs to inhibit inflammation and neurodegeneration while limiting side effects. Further elucidation of the pathophysiology of disease may provide new clinical targets and disease-relevant biomarkers that, in combination with proteomics, may help personalize treatment to individual patients.

Type I interferons inhibition of inflammatory T helper cell responses in systemic lupus erythematosus

T helper (Th) cells play a central role in systemic lupus erythematosus (SLE). Activated autoreactive Th cells provide the help required for autoreactive B cells to differentiate and produce pathogenic autoAbs. Both autoAb-containing immune complexes and direct effects of inflammatory Th cells promote tissue injury and organ damage. In SLE, triggering of plasmacytoid dendritic cell (pDC) Toll-like receptors by autoimmune complexes containing nucleic acid autoantigens stimulates pDC secretion of high levels of type I interferons (IFN-alpha/beta). Study of SLE patients and murine disease models implicate these type I IFNs as key disease effectors. However, the role of pDC-derived type I IFNs in regulating the inflammatory function of Th cells in SLE is unknown. Although, type I IFNs are classically considered to promote Th1-mediated inflammation, they can also act as potent inhibitors of both Th1 and Th17 inflammatory cell responses. Work of ourselves and others leads us to hypothesize that if initiated during stages of SLE when Th cell-mediated tissue inflammation is absent or minimal, such as early in the disease or during periods of remission, type I IFN neutralization will disrupt the cycle of systemic autoimmune induction and disease. However, if initiated during advanced stages of disease when there is substantial ongoing Th1 (and possibly Th17) cell-mediated inflammation, targeting type I IFNs will exacerbate the Th cell-mediated inflammatory disease and thus potentiate end-organ damage and destruction. This has important implications for the application of the numerous anti-type I IFN therapies currently under development for SLE treatment.

Interferon-beta treatment for multiple sclerosis

Multiple sclerosis (MS) is the leading nontraumatic cause of neurologic disability in young adults. Interferon-beta, approved for use in 1993, was the first treatment to modify the course and prognosis of the disease and remains a mainstay of MS treatment. Numerous large-scale clinical trials in early, active patient populations have established the clinical efficacy of interferon-beta in reducing relapses and delaying disability progression. Although its mechanism of action remains incompletely understood, a reduction in active lesions seen on magnetic resonance imaging implies primary anti-inflammatory properties, a mechanism supported by basic immunologic research. Variation in individual patient responsiveness to interferon-beta may be due to disease variability or differential induction of interferon-stimulated genes. The magnitude of the therapeutic effect appears to be similar among products, but the optimal dose, route, and frequency of administration of the drug remain uncertain.

High dose cyclophosphamide preferentially targets naïve T (CD45/CD4/RA+) cells in CIDP and MS patients

INTRODUCTION

T cells occupy a central role in MS and CIDP pathogenesis. High dose cyclophosphamide's in-vivo cytotoxic-effect on circulating memory and naïve T cells is unknown.

METHOD

Three MS and five CIDP patients received cyclophosphamide (200 mg/kg) for refractory disease. Before and after chemotherapy administration, peripheral blood T-cell subsets were determined. Patients underwent serial neurologic evaluations quarterly.

RESULTS

Cyclophosphamide uniformly decreased clinical disease activity. Compared to memory T cells, naïve T cells were preferentially eradicated.

DISCUSSION

Cyclophosphamide effectiveness in autoimmune illness may result from Naïve T-cell destruction, as this compartment may be the source of autoreactive lymphocytes.

Seasonal variation and the immune response: a fish perspective

The environment in which an animal lives affects the physiology and psychology of that animal. The greater the distance from the equator the more profound this influence becomes, as the environment becomes more variable over the years. Temperature, photoperiod, precipitation and other environmental conditions, which are directly or indirectly controlled by the season, can affect an animal. It is becoming apparent that these conditions may impact on the immune system, and this can affect animal health. This review looks at the known mechanisms for transducing environmental cues and how these can affect immune parameters and function. The main focus is fish, especially in relation to aquaculture and the associated disease risks. Work on other animal classes is included for comparison.

Blockade of TLR9 agonist-induced type I interferons promotes inflammatory cytokine IFN-gamma and IL-17 secretion by activated human PBMC

Type I interferons (IFN) (IFN-alpha/beta) are recognized as both inhibitors and effectors of autoimmune disease. In multiple sclerosis, IFN-beta therapy appears beneficial, in part, due to its suppression of autoimmune inflammatory Th cell responses. In contrast, in systemic lupus erythematosus (SLE) triggering of plasmacytoid DC (pDC) Toll-like receptors (TLRs) by autoimmune complexes (autoICs) results in circulating type I IFN that appear to promote disease by driving autoantigen presentation and autoantibody production. To investigate how pDC-derived type I IFN might regulate Th cells in SLE, we examined a model in which sustained pDC stimulation by autoICs is mimicked by pretreating normal human PBMC with TLR9 agonist, CpG-A. Subsequently, PBMC Th cells are activated with superantigen, and APC are activated with CD40L. The role of CpG-A/TLR9-induced type I IFN in regulating PBMC is determined by blocking with virus-derived soluble type I IFN receptor, B18R. In summary, pretreatment with either rhIFN-alpha/beta or CpG-A inhibits PBMC secretion of superantigen-induced IFN-gamma and IL-17, and CD40L-induced IL-12p70 and IL-23. B18R prevents these effects. Data indicate that CpG-A-induced type I IFN inhibit IL-12p70-dependent PBMC IFN-gamma secretion by enhancing IL-10. Our results suggest that in SLE, circulating type I IFN may potentially act to inhibit inflammatory cytokine secretion.

The interleukin-10 levels as a potential indicator of positive response to interferon beta treatment of multiple sclerosis patients

OBJECTIVES

Only a part of MS patients treated with interferon beta (IFN) respond positively to the applied treatment and to date no parameter predicting the response to treatment has been found. The aim of the study was to determine whether the levels of interleukin-10 and -12 (IL-10 and IL-12) might be the parameters enabling us to distinguish those patients who would best respond to therapy before the IFN treatment.

PATIENTS AND METHODS

The study included 29 patients with clinically definite relapsing-remitting MS treated with IFN beta. In all of them the levels of IL-10 and IL-12 in blood serum and cerebrospinal fluid were determined before treatment using ELISA method. After the 2-year therapy the patients responding and nonresponding to IFN therapy were distinguished on the basis of clinical parameters.

RESULTS

In the patients responding positively to IFN treatment the level of IL-10 in blood serum before treatment was found to be significantly lower (p<0.05) and distinctively differentiated responders from nonresponders. The IL-12 levels were similar both in cerebrospinal fluid and serum and no significant differences between responders and nonresponders were found.

CONCLUSION

Our observations suggest that IL-10 level may be a useful parameter to identify the patients potentially responding to IFN therapy.

Drug Insight: interferon treatment in multiple sclerosis

Multiple sclerosis (MS) is a chronic demyelinating disease of the CNS. Between 1987 and 1997, clinical trials of three preparations of recombinant interferon-beta were conducted in patients with MS, ushering in a new therapeutic era. These medications have demonstrable benefits and seem to be safe; they represent an important advance in MS treatment. All three formulations of interferon-beta had modest effects on relapses and short-term progression of disability, but the effects on MRI lesion parameters were more substantial. The benefits were greater in clinically isolated syndromes and relapsing-remitting MS than in secondary progressive MS. Although these drugs have been shown to be effective, however, their long-term impact on clinically relevant disability progression is uncertain, and there are many areas of controversy in the MS field regarding the use of these products. There is still a need for more effective treatments, which might include new agents or combination therapies.

Murine glia express the immunosuppressive cytokine, interleukin-10, following exposure toBorrelia burgdorferi orNeisseria meningitidis

There is growing appreciation that resident glial cells can initiate and/or regulate inflammation following trauma or infection in the central nervous system (CNS). We have previously demonstrated the ability of microglia and astrocytes, resident glial cells of the CNS, to respond to bacterial pathogens by rapid production of inflammatory mediators. However, inflammation within the brain parenchyma is notably absent during some chronic bacterial infections in humans and nonhuman primates. In the present study, we demonstrate the ability of the immunosuppressive cytokine, interleukin-10 (IL-10), to inhibit inflammatory immune responses of primary microglia and astrocytes to B. burgdorferi and N. meningitidis, two disparate gram negative bacterial species that can cross the blood-brain barrier in humans. Importantly, we demonstrate that these organisms induce the delayed production of significant quantities of IL-10 by both microglia and astrocytes. Furthermore, we demonstrate that such production occurs independent of the actions of bacterial lipopolysaccharide and is secondary to the autocrine or paracrine actions of other glia-derived soluble mediators. The late onset of IL-10 production by resident glia following activation, the previously documented expression of specific receptors for this cytokine on microglia and astrocytes, and the ability of IL-10 to inhibit bacterially induced immune responses by these cells, suggest a mechanism by which resident glial cells can limit potentially damaging inflammation within the CNS in response to invading pathogens, and could explain the suppression of inflammation seen within the brain parenchyma during chronic bacterial infections.

Interferon-alpha2a is sufficient for promoting dendritic cell immunogenicity

Type I interferons (IFNs) are widely used therapeutically. IFN-alpha2a in particular is used as an antiviral agent, but its immunomodulatory properties are poorly understood. Dendritic cells (DCs) are the only antigen-presenting cells able to prime naive T cells and therefore play a crucial role in initiating the adaptive phase of the immune response. We studied the effects of IFN-alpha2a on DC maturation and its role in determining Th1/Th2 equilibrium. We found that IFN-alpha2a induced phenotypic maturation of DCs and increased their allostimulatory capacity. When dendritic cells were stimulated simultaneously by CD40 ligation and IFN-alpha2a, the production of interleukin (IL)-10 and IL-12 was increased. In contrast, lipopolysaccharide (LPS) stimulation in the presence of IFN-alpha2a mainly induced IL-10 release. The production of IFN-gamma and IL-5 by the responder naive T cells was also amplified in response to IFN-alpha2a-treated DCs. Furthermore, IL-12 production by IFN-alpha2a-treated DCs was enhanced further in the presence of anti-IL-10 antibody. Different results were obtained when DCs were treated simultaneously with IFN-alpha2a and other maturation factors, in particular LPS, and then stimulated by CD40 ligation 36 h later. Under these circumstances, IFN-alpha2a did not modify the DC phenotype, and the production of IL-10/IL-12 and IFN-gamma/IL-5 by DCs and by DC-stimulated naive T cells, respectively, was inhibited compared to the effects on DCs treated with maturation factors alone. Altogether, this work suggests that IFN-alpha2a in isolation is sufficient to promote DC activation, however, other concomitant events, such as exposure to LPS during a bacterial infection, can inhibit its effects. These results clarify some of the in vivo findings obtained with IFN-alpha2a and have direct implications for the design of IFN-alpha-based vaccines for immunotherapy.

Suppression of Ongoing Disease in a Nonhuman Primate Model of Multiple Sclerosis by a Human-Anti-Human IL-12p40 Antibody

IL-12p40 is a shared subunit of two cytokines with overlapping activities in the induction of autoreactive Th1 cells and therefore a potential target of therapy in Th1-mediated diseases. We have examined whether ongoing disease in a nonhuman primate model of multiple sclerosis (MS) can be suppressed with a new human IgG1kappa Ab against human IL-12p40. Lesions developing in the brain white matter were visualized and characterized with standard magnetic resonance imaging techniques. To reflect the treatment of MS patients, treatment with the Ab was initiated after active brain white matter lesions were detected in T2-weighted images. In placebo-treated control monkeys we observed the expected progressive increase in the total T2 lesion volume and markedly increased T2 relaxation times, a magnetic resonance imaging marker of inflammation. In contrast, in monkeys treated with anti-IL-12p40 Ab, changes in the total T2 lesion volume and T2 relaxation times were significantly suppressed. Moreover, the time interval to serious neurological deficit was delayed from 31 +/- 10 to 64 +/- 20 days (odds ratio, 0.312). These results, in a disease model with high similarity to MS, are important for ongoing and planned trials of therapies that target IL-12 and/or IL-23.

Microglia and multiple sclerosis

Microglia participate in all phases of the multiple sclerosis (MS) disease process. As members of the innate immune system, these cells have evolved to respond to stranger/danger signals; such a response within the central nervous system (CNS) environment has the potential to induce an acute inflammatory response. Engagement of Toll-like receptors (TLRs), a major family of pattern-recognition receptors (PRRs), provides an important mechanism whereby microglia can interact with both exogenous and endogenous ligands within the CNS. Such interactions modulate the capacity of microglia to present antigens to cells of the adaptive immune system and thus contribute to the initiation and propagation of the more sophisticated antigen-directed responses. This inflammatory response introduces the potential for bidirectional feedback between CNS resident and infiltrating systemic cells. Such interactions acquire particular relevance in the era of therapeutics for MS because the infiltrating cells can be subjected to systemic immunomodulatory therapies known to change their functional properties. Phagocytosis by microglia/macrophages is a hallmark of the MS lesion; however, the extent of tissue damage and the type of cell death will dictate subsequent innate responses. Microglia/macrophages are armed with a battery of effector molecules, such as reactive nitrogen species, that may contribute to CNS tissue injury, specifically to the injury of oligodendrocytes that is associated with MS. A therapeutic challenge is to modulate the dynamic properties of microglia/macrophages so as to limit potentially damaging innate responses, to protect the CNS from injury, and to promote local recovery.

The production of IL-1 receptor antagonist in IFN-beta-stimulated human monocytes depends on the activation of phosphatidylinositol 3-kinase but not of STAT1

IFN-beta induces the production of secreted IL-1R antagonist (sIL-1Ra) without triggering synthesis of the agonist IL-1beta in human monocytes. This might account for its anti-inflammatory properties. Canonically, IFN-beta signals through activation of JAK/STAT pathway, although PI3K and MAPK have also been involved. In this study, the role of PI3K, MEK1, and STAT1 in IFN-beta-induced sIL-1Ra production is investigated in freshly isolated human blood monocytes. PI3K, but not MEK1 activation is essential for sIL-1Ra production in monocytes treated with IFN-beta, as demonstrated by using the respective inhibitors of PI3K and MEK1, Ly294002 and PD98059. The use of cycloheximide and actinomycin D shows that sIL-1Ra was an immediate early gene induced by IFN-beta and that PI3K was controlling sIL-1Ra gene transcription. Although both inhibitors of PI3K and MEK1 diminished the Ser(727) phosphorylation of STAT1 induced by IFN-beta, only Ly294002 inhibited sIL-1Ra production. Furthermore, the inhibition of STAT1-Ser(727) phosphorylation by Ly294002 did not affect STAT1 translocation, suggesting that STAT1 was not involved in sIL-1Ra gene induction. This was confirmed in monocytes that were transfected with small interfering RNA specifically targeting STAT1. Indeed, monocytes in which effective STAT1 gene knockdown was achieved were fully responsive to IFN-beta in terms of sIL-1Ra production. Taken together, the present data demonstrate that the induction of sIL-1Ra transcription and production by IFN-beta in human monocytes involved PI3K, but not STAT1 activation.

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.

Expression and visualization of a human interferon-beta-enhanced green fluorescent protein chimeric molecule in cultured cells

We have constructed a recombinant cDNA encoding the chimeric protein between human IFN-beta (HuIFN-beta) and enhanced green fluorescent protein (EGFP) to elucidate the intracellular localization of IFN-beta. Transient expression of the chimeric molecule, HuIFN-beta-EGFP, in L cells demonstrated that the chimeric molecule secreted from the cells had an intact biological activity as far as antiviral effect was concerned. Immunostaining of the transfected cells using anti-HuIFN-beta antibody demonstrated that green-fluorescence was co-localized with the IFN signal and its profile was similar to IFN signals in the cells transfected with HuIFN-beta expressing plasmid DNA. These results indicate that the HuIFN-beta-EGFP chimeric gene was expressed as a chimeric protein and the chimera was transported via the regular secretory pathway in the cells. In other cell types, the fluorescence derived from the chimeric protein was also seen on cytoplasmic vesicular structures. These results suggest that HuIFN-beta-EGFP will be a useful tool to investigate the intracellular trafficking processes of HuIFN-beta in a variety of cell types.

Microarray gene expression profiling of chronic active and inactive lesions in multiple sclerosis

Multiple sclerosis, a primary autoimmune disease of the central nervous system has been characterized by the presence of the demyelinating lesions (plaques) in the CNS. To further understand the gene transcription status of the two most common lesions, chronic active and chronic inactive, we have performed a cDNA microarray analysis of these two lesion type. Comparative analysis of differential gene expression of chronic active and inactive lesions have confirmed the existence of a significant difference in the transcriptional profiles of these two lesion types in both marginal and central areas. Different sets of genes were highlighted, including genes of inflammatory characteristics, apoptosis related and stress-induced, indicating their potential role in MS pathogenesis.

Time-dependent cytokine deviation toward the Th2 side in Japanese multiple sclerosis patients with interferon beta-1b

To address the immune mechanism sustaining interferon beta (IFNbeta) efficacy in multiple sclerosis (MS), we longitudinally analyzed expressions of IFN-gamma, IL-4, IL-5 and IL-13 in CD4+ T cells and CD8+ T cells in 22 Japanese MS patients (16 patients with conventional MS and 6 with opticospinal MS) undergoing IFNbeta using flow cytometry. During the 48-week observation period, five opticospinal MS patients (83%) relapsed compared to only four conventional MS patients (25%); the frequency of relapsed patients was significantly higher in the former (p=0.046). The effects of IFNbeta on individual cytokines were time-dependent and altered cytokine productions were particularly evident in CD4+ rather than CD8+ T cells. A decreased intracellular IFN-gamma/IL-4 ratio in CD4+ T cells was thus evident soon after the initiation of therapy, and persisted for the entire 1 year follow-up period, regardless of whether or not the patient relapsed (p<0.01). IFNbeta treatment resulted in a rapid increase in the percentage of IFN-gamma- IL-4+ and IL-13+ CD4+ T cells 1 week after the initiation of therapy and high values were sustained for 6 months but declined to the baseline over 1 year. Later, the percentage of IFN-gamma+ IL-4- CD4+ T cells decreased significantly from weeks 24 through 48 of therapy (p<0.01). When comparisons with the pretreatment values were made for each subtype of MS, a significant reduction of IFN-gamma+ IL-4- CD4+ T cell percentages was shown in conventional MS (p<0.0001), but not in opticospinal MS. Moreover, when such a comparison was made by the presence or absence of relapse during therapy, a significant reduction of IFN-gamma+ IL-4- CD4+ T cell percentages was observed in MS patients without relapse (p<0.01). Thus, a reduction of IFN-gamma+ IL-4- CD4+ T cell percentages in the late phase of therapy is considered important for reducing relapse in conventional MS. When the expression patterns of IFN-gamma, IL-4, IL-5 and IL-13 in CD4+ T cells and CD8+ T cells were compared between patients with and without relapse during therapy, the only significant difference was an increase in the IL-13+ CD4+ T cell percentages in patients with relapse compared to those without (p<0.05). The results indicate that in CD4+ T cells IL-4 was preferentially up-regulated in the early course and IFN-gamma was down-regulated in the late phase of IFNbeta therapy. The net effect of IFNbeta on the immune balance was entirely toward type 2 immune deviation, possibly contributing to its beneficial effects on MS.

Cytokine shifts and tolerance in experimental autoimmune encephalomyelitis

Cytokines play an important role in the pathogenesis of both multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Effective treatments for both diseases have been shown to alter cytokines in the central nervous system and in activated mononuclear cells. EAE is an animal model that mimics many aspects of multiple sclerosis, and has been widely used to study the mechanisms of disease and therapeutic approaches to multiple sclerosis. Cytokines play an important role in regulation of disease expression in EAE, and in tolerance to disease induction. In this review, we will summarize the current findings on the role of cytokine shifts in the induction of tolerance in EAE. In addition, we will discuss modulation of EAE by altered expression of members of the cytokineregulated Jak/STAT intracellular signaling pathway.

Elevated osteopontin levels in active relapsing-remitting multiple sclerosis

In the search for proteins that might play a role in the pathogenesis of multiple sclerosis (MS), osteopontin (OPN) has been identified as the most prominent cytokine-encoding gene expressed within MS lesions. Here, we report significantly increased OPN protein levels in plasma of relapsing-remitting MS patients. In contrast, OPN protein levels in primary progressive and secondary progressive MS patients were similar to healthy control levels. Interestingly, active relapsing-remitting patients had higher OPN protein levels than patients without relapses.

cDNA microarray analysis in multiple sclerosis lesions: detection of genes associated with disease activity

cDNA microarray analysis of the regions of pathologically proven different activity of multiple sclerosis lesions was performed. Major differences in gene expression (DGE) occurred between the lesion margin and lesion centre in active lesions studied (57 and 69 genes differentially expressed, respectively), whereas the margins and centres of silent lesions showed markedly reduced heterogeneity (only 11 and two genes differentially expressed, respectively). To compare differences between chronic active and silent lesions, we performed DGE comparison of the pooled data from both types of lesions. The major DGE occurred at the lesion margin, 156 (26; 5%), the greater number representing upregulated genes at the margin of active lesions (15%). Fourteen genes were found to be significantly upregulated in marginal versus central zones in active lesions examined. These genes comprised predominantly inflammation/immune-related factors. We also performed DGE analysis of pooled genes upregulated at the margin of active lesions and found that among the 50 genes showing differences, nine out of 14 were identified in the previous analysis of overlapping differentially expressed genes. Thus this microarray analysis has identified a novel set of genes associated with lesion activity in multiple sclerosis, many of them not previously linked with the disease.

Interleukin-1beta promotes oligodendrocyte death through glutamate excitotoxicity

Glutamate excitotoxicity is implicated in the progressive loss of oligodendrocytes in multiple sclerosis, but how glutamate metabolism is dysregulated in the disease remains unclear. Because there is microglia activation in all stages of multiple sclerosis, we determined whether a microglia product, interleukin-1beta, could provide the mechanism for glutamate excitotoxicity. We found that whereas interleukin-1beta did not kill oligodendrocytes in pure culture, it produced apoptosis of oligodendrocytes in coculture with astrocytes and microglia. This requirement for a mixed glia environment suggests that interleukin-1beta impairs the well-described glutamate-buffering capacity of astrocytes. In support, antagonists at AMPA/kainate glutamate receptors, NBQX and CNQX, blocked the interleukin-1beta toxicity to oligodendrocytes. Another microglia/macrophage cytokine, tumor necrosis factor-alpha, also evoked apoptosis of oligodendrocytes in a mixed glia environment in an NBQX-blockable manner. These results provide a mechanistic link between the persistent and insidious microglia activation that is evident in all stages of multiple sclerosis, with the recent appreciation that glutamate excitotoxicity leads to the destruction of oligodendrocytes in the disease.

Pharmacogenomic analysis of interferon receptor polymorphisms in multiple sclerosis

Multiple sclerosis (MS) is a common inflammatory disease of the central nervous system characterized by progressive neurological dysfunction. No curative therapy is currently available, and approximately 80-90% of afflicted individuals are ultimately disabled. Interferon beta (IFNbeta) has been shown to decrease clinical relapses, reduce brain disease activity, and possibly slow progression of disability. However, the overall effect of treatment is partial and a substantial number of patients are considered poor or nonresponders. For this report, we tested the pharmacogenomic effects of eight polymorphisms in the interferon receptor genes (IFNAR1 and IFNAR2) in a group of 147 patients undergoing open-label IFNbeta therapy. Overall, no significant differences in the distribution of responders and nonresponders, classified based on prospectively acquired primary and secondary clinical end points, were observed when stratified by any of the studied IFNAR gene polymorphisms. A trend detected with a single nucleotide polymorphism SNP 16469 (A/T) located at the third intron of the IFNAR1 gene, suggesting modest association with relapse-free status, will require confirmation in an independent data set. In addition, no significant association was observed of any of the IFNAR gene polymorphisms with susceptibility to MS, as studied by a family-based association analysis.

Human brain endothelial cells supply support for monocyte immunoregulatory functions

Blood-derived monocytic cells comprise a significant component of most inflammatory responses that occur in the CNS. We utilized human brain-derived endothelial cells (HBECs) coated membranes in Boyden chambers to assess immune function related properties of human blood-derived monocytes following interaction with HBECs. Monocytes in contact with HBECs maintained functional antigen-presenting capacity and chemokine/cytokine production in contrast to monocytes that migrated through the HBEC barrier. These results indicate that HBECs, although themselves incapable of serving as competent antigen-presenting cells during the course of inflammatory CNS disorders, supply support needed for infiltrating perivascular monocytes to maintain their functions. Monocyte migration across HBECs was inhibited by interferon-beta.

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.

Interleukin-10 polymorphisms in Spanish multiple sclerosis patients

Interleukin-10 (IL-10) is an anti-inflammatory cytokine that may be an important regulator in multiple sclerosis (MS) pathogenesis. IL-10 gene contains three single nucleotide polymorphisms (SNPs) and two polymorphic microsatellites in the 5'-flanking region. Our aim was to ascertain if any of these polymorphic markers is associated or linked to MS among Spanish patients. We have genotyped 300 patients and 357 ethnically matched controls for the microsatellites, and most of them also for the promoter SNPs. We included in this study the parents of 63 patients in order to perform a TDT analysis as well. IL-10G12 allele was significantly increased in MS patients (17% versus 11% in controls; p=0.004; p(c)<0.05). No other allele showed a significant difference between patients and controls, and the TDT analysis yielded negative results. The data indicate that IL-10 is not a major susceptibility locus in MS, but in our population it might, however, have a minor role.

Immunological indicators of disease activity and prognosis in multiple sclerosis

The need to ensure an accurate diagnosis and proper treatment for multiple sclerosis patients, considering the various clinical and immunopathological subtypes of the disease, requires the identification of biomarkers that measure disease activity and predict the course of disease development in individual patients. Moreover, the identification of effective indicators will lead not only to optimized patient treatment but also to the development of better tools for evaluating clinical trials. Recent studies focusing on the identification of possible immunological markers in multiple sclerosis will be reviewed.

Multiple sclerosis

Multiple sclerosis is the prototype inflammatory autoimmune disorder of the central nervous system and, with a lifetime risk of one in 400, potentially the most common cause of neurological disability in young adults. As with all complex traits, the disorder results from an interplay between as yet unidentified environmental factors and susceptibility genes. Together, these factors trigger a cascade of events, involving engagement of the immune system, acute inflammatory injury of axons and glia, recovery of function and structural repair, post-inflammatory gliosis, and neurodegeneration. The sequential involvement of these processes underlies the clinical course characterised by episodes with recovery, episodes leaving persistent deficits, and secondary progression. The aim of treatment is to reduce the frequency, and limit the lasting effects, of relapses, relieve symptoms, prevent disability arising from disease progression, and promote tissue repair. Despite limited success in each of these categories, everyone touched by multiple sclerosis looks for a better dividend from applying an improved understanding of the pathogenesis to clinical management.

Interferon-beta therapy for multiple sclerosis induces reciprocal changes in interleukin-12 and interleukin-10 production

Interleukin-12 is critical to the pathogenesis of experimental autoimmune encephalomyelitis in multiple species. Interleukin-10, a dominant endogenous inhibitor of interleukin-12, is largely protective in these experimental surrogates for multiple sclerosis. Such data have suggested that an interleukin-12/interleukin-10 immunoregulatory circuit is a key determinant of disease expression in experimental autoimmune encephalomyelitis. For multiple sclerosis itself, compatible cytokine data have been reported. The mechanisms underlying the beneficial effects of interferon-beta in multiple sclerosis remain unclear, hampering the search for more effective therapies. Of note, interferon-beta has reciprocal effects on these cytokines in vitro, suppressing interleukin-12 and augmenting interleukin-10 production. To examine the effects of interferon-beta on the interleukin-12/interleukin-10 axis in multiple sclerosis, we characterized the production of these cytokines by peripheral blood mononuclear cells from patients beginning therapy with interferon-beta. Before therapy, multiple sclerosis patients exhibited increased stimulatable interleukin-12 production compared with controls. Interferon-beta therapy leads to inhibition of interleukin-12 and augmentation of interleukin-10 production, significantly elevating the ratio of secreted interleukin-10 to interleukin-12. These effects, observed equally in patients with relapsing-remitting and progressive disease, indicate that interferon-beta affects the interleukin-12/interleukin-10 axis in ways thought to be beneficial to multiple sclerosis patients. More specific therapeutic targeting of these pathways may be warranted.

Cytokines and autoimmunity

Cytokines have crucial functions in the development, differentiation and regulation of immune cells. As a result, dysregulation of cytokine production or action is thought to have a central role in the development of autoimmunity and autoimmune disease. Some cytokines, such as interleukin-2, tumour-necrosis factor and interferons--ostensibly, the 'bad guys' in terms of disease pathogenesis--are well known for the promotion of immune and inflammatory responses. However, these cytokines also have crucial immunosuppressive functions and so, paradoxically, can also be 'good guys'. The balance between the pro-inflammatory and immunosuppressive functions of these well-known cytokines and the implications for the pathogenesis of autoimmune disease is the focus of this review.

Cytokines and acute neurodegeneration

Cytokines have been implicated as mediators and inhibitors of diverse forms of neurodegeneration. They are induced in response to brain injury and have diverse actions that can cause, exacerbate, mediate and/or inhibit cellular injury and repair. Here we review evidence for the contribution of cytokines to acute neurodegeneration, focusing primarily on interleukin 1 (IL-1), tumour necrosis factor-alpha (TNFalpha) and transforming growth factor-beta (TGFbeta). TGFbeta seems to exert primarily neuroprotective actions, whereas TNFalpha might contribute to neuronal injury and exert protective effects. IL-1 mediates ischaemic, excitotoxic and traumatic brain injury, probably through multiple actions on glia, neurons and the vasculature. Understanding cytokine action in acute neurodegeneration could lead to novel and effective therapeutic strategies, some of which are already in clinical trials.