Exacerbations of multiple sclerosis in patients treated with gamma interferon

A predictable sequential determinant spreading cascade invariably accompanies progression of experimental autoimmune encephalomyelitis: a basis for peptide-specific therapy after onset of clinical disease

The development of autoimmune disease is accompanied by the acquired recognition of new self-determinants, a process commonly referred to as determinant spreading. In this study, we addressed the question of whether determinant spreading is pathogenic for progression of chronic-relapsing experimental autoimmune encephalomyelitis (EAE), a disease with many similarities to multiple sclerosis (MS). Our approach involved a systematic epitope mapping of responses to myelin proteolipid protein (PLP) as well as assaying responses to known encephalitogenic determinants of myelin basic protein (MBP 87-89) and myelin oligodendrocyte glycoprotein (MOG 92-106) at various times after induction of EAE in (SWR X SJL)F1 mice immunized with PLP 139-151. We found that the order in which new determinants are recognized during the course of disease follows a predictable sequential pattern. At monthly intervals after immunization with p139-151, responses to PLP 249-273, MBP 87-99, and PLP 137-198 were sequentially accumulated in al mice examined. Three lines of evidence showed that determinant spreading is pathogenic for disease progression: (a) spreading determinants mediate passive transfer of acute EAE in naive (SWR X SJL)F1 recipients; (b) an invariant relationship exists between the development of relapse/progression and the spreading of recognition to new immunodominant encephalitogenic determinants; and (c) after EAE onset, the induction of peptide-specific tolerance to spreading but not to nonspreading encephalitogenic determinants prevents subsequent progression of EAE. Thus, the predictability of acquired self-determinant recognition provides a basis for sequential determinant-specific therapeutic intervention after onset of the autoimmune disease process.

Serum and cerebrospinal fluid levels of soluble adhesion molecules in multiple sclerosis: predominant intrathecal release of vascular cell adhesion molecule-1

Activated cerebral vascular endothelial cells express leukocyte, vascular cell, and intracellular adhesion molecules (E-selectin, VCAM-1 and ICAM-1) which facilitate leukocyte adhesion to endothelium and migration into inflammatory lesions. Paired serum and cerebrospinal fluid (CSF) levels of soluble (s) E-selectin, sVCAM-1 and sICAM-1 were determined by ELISA in patients with clinically definite MS in relapse, and patients with other inflammatory (IND) and non-inflammatory neurological disease (NIND). CSF levels of sVCAM-1 and sICAM-1 were significantly increased in MS patients compared to IND and NIND patients. Elevation of CSF sVCAM-1 in MS patients was the most marked finding (P = 0.0001) and an increased sVCAM-1 index indicated that this was due to intrathecal release of sVCAM-1. There were no differences in serum and CSF sE-selectin levels between the study groups. Measurement of the sVCAM-1 index may provide a marker of disease activity in patients with clinically definite MS.

Expression of costimulatory molecules B7-1 (CD80), B7-2 (CD86), and interleukin 12 cytokine in multiple sclerosis lesions

Resting autoreactive T cells are present in the circulation of normal individuals without pathologic consequences. In autoimmune animal models, stimulation of these self-reactive T cells in the presence of costimulatory molecules B7-1 results in T cell-mediated autoimmune disease, whereas B7-2 stimulation generates regulatory autoreactive T cells that abrogate disease severity. Thus, reactivation in the brain of myelin-autoreactive T cells by antigen with costimulatory molecules may be a critical event in the pathophysiology of multiple sclerosis (MS), a putative autoimmune disease of central nervous system (CNS) myelin. We investigated the expression of cytokines and costimulatory molecules in a panel of 41 histologically characterized CNS specimens from 15 MS and 10 control cases using semiquantitative reverse transcriptase-polymerase chain reaction and immunocytochemistry. In four cases, vascular CNS infarcts with inflammation were compared with MS plaques from the same brain. We observed increased expression of B7-1 and interleukin (IL) 12p40 in acute MS plaques, particularly from early disease cases but not in inflammatory infarcts. B7-1 staining was localized predominantly to the lymphocytes in perivenular inflammatory cuffs but not the parenchyma. In contrast, B7-2 was expressed predominantly on macrophages both in MS lesions of varied time duration and in inflammatory infarcts. These findings indicate that an early event in the initiation of MS involves upregulation of B7-1 and IL-12, resulting in conditions that maximally stimulate T cell activation and induction of T helper 1-type immune responses.

Interferon (IFN) beta acts downstream of IFN-gamma-induced class II transactivator messenger RNA accumulation to block major histocompatibility complex class II gene expression and requires the 48-kD DNA-binding protein, ISGF3-gamma

Interferon (IFN) gamma, a cardinal proinflammatory cytokine, induces expression of the gene products of the class II locus of the major histocompatibility complex (MHC), whereas IFN-alpha or -beta suppresses MHC class II expression. The mechanism of IFN-beta-mediated MHC class II inhibition has been unclear. Recently, a novel factor termed class II transactivator (CIITA) has been identified as essential for IFN-gamma-induced MHC class II transcription. We studied the status of IFN-gamma-induced CIITA messenger RNA (mRNA) accumulation and CIITA-driven transactivation in IFN-beta-treated cells and used cell lines that had defined defects in the type I IFN response pathway to address the roles of IFN signaling components in the inhibition of MHC class II induction. IFN-beta treatment did not suppress IFN-gamma-induced accumulation of CIITA mRNA. After cells were stably transfected with CIITA, endogenous MHC class II genes were constitutively expressed, and MHC class II promoters, delivered by transfection, were actively transcribed in CIITA-expressing cells. Expression of these promoters was significantly impaired by pretreatment with IFN-beta. These results suggest that IFN-beta acts downstream of CIITA mRNA accumulation, and acts in part by reducing the functional competence of CIITA for transactivating MHC class II promoters. IFN stimulated gene factor 3 (ISGF3) gamma was essential for IFN-beta to mediate inhibition of MHC class II induction, regardless of whether MHC class II transcription was stimulated by IFN-gamma or directly by CIITA expression. Results of these experiments suggest that inhibition of MHC class II in IFN-beta-treated cells requires expression of gene(s) directed by the ISGF3-IFN-stimulated response element pathway, and that these gene product(s) may act by blocking CIITA-driven transcription of MHC class II promoters.

Dysmyelination in class I MHC transgenic mice

Why is it that oligodendrocytes do not normally express major histocompatibility complex (MHC) molecules? To examine the effect of aberrant MHC expression in oligodendrocytes, transgenic mice have been produced which expressed the class I MHC gene, H-2Kb, under direction of the MBP promoter [Turnley et al. (1991b) Nature, 353:566-569; Yoshioka et al. (1991) Mol. Cell. Biol., 11:5479-5486]. A proportion of these mice exhibited a shivering phenotype, with tonic seizures and early death. Oligodendrocyte function and viability was shown to be affected, resulting in severe dysmyelination of the CNS. Is this phenomenon of cell damage due to aberrant expression of MHC molecules restricted to oligodendrocytes, and could other, non-MHC molecules, when aberrantly expressed, result in similar cell damage? This paper discusses these questions and examines possible mechanisms for the oligodendrocyte damage and hypomyelination observed in these transgenic mice. Finally, the implications of aberrant MHC expression in oligodendrocytes for demyelinating diseases such as multiple sclerosis are discussed.

Inhibition of T cell responses by activated human CD8+ T cells is mediated by interferon-gamma and is defective in chronic progressive multiple sclerosis

The autologous mixed lymphocyte reaction (AMLR) involves the activation of T cells by autologous antigen presenting cells. Cells are generated during the course of the AMLR that have suppressive properties in vitro. In the present study we investigated the induction of CD8+ T cells in the AMLR with suppressive properties and the mechanism by which these cells downregulate in vitro proliferative responses. Purified CD8+ but not CD4+ T cells activated in the AMLR in conditioned medium inhibited proliferation of autologous T cells by anti-CD3 or PPD. Nonactivated CD8+ T cells did not suppress. The CD8+ T cells activated in the AMLR in the presence of conditioned medium (CD8+ Tact) were CD11b negative and were noncytotoxic. The inhibitory effect of CD8+ Tact cells was completely abrogated by anti-IFN-gamma antibody, but not by anti-IL-4, anti-IL-10, or anti-TGF-beta antibody. The induction of CD8+ Tact cells in the AMLR was blocked by anti-IL-2 or by anti-GM-CSF antibody and the combination of these two recombinant cytokines could support the induction of suppressive CD8+ Tact cells. CD8+ Tact cells were defective in patients with chronic progressive multiple sclerosis (MS) as compared to patients with relapsing-remitting MS or normal controls. Our studies provide a basis for understanding the mechanism of suppression by human CD8+ T cells in terms of specific cytokines, and demonstrate the potential importance of these cells in a human autoimmune disease as their function is defective in patients with progressive MS.

Is there a case for a virus aetiology in multiple sclerosis?

Multiple Sclerosis (MS) is a devastating demyelinating disease with a very high prevalence in North-East Scotland and in the Orkney and Shetland Islands. MS appears to be a multifactorial disorder with environmental and genetic elements and it has been proposed that these, in tandem, provoke an autoimmune response giving rise to the disease. Although there is no direct evidence of a specific virus being involved in MS, there are nevertheless grounds for suspecting a viral association. This review discusses these aspects of MS and suggests that a more aggressive approach to unravelling the role of viruses is needed.

The antidepressant rolipram suppresses cytokine production and prevents autoimmune encephalomyelitis

In multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE) the cytokines tumour necrosis factor-alpha (TNF), lymphotoxin-alpha (LT), and interferon-gamma (IFN-gamma) are of central pathogenetic importance. A therapy capable of stopping neurological deterioration in MS patients is not yet available. Here, we report that rolipram, a selective type IV phosphodiesterase inhibitor, stereospecifically suppresses the production of TNF/LT and less strongly also IFN-gamma in human and rat auto-reactive T cells. Moreover, we show that rolipram is an effective treatment for EAE. Rolipram has extensively been studied in humans for the treatment of depression, but has not yet been marketed. The data presented here identify rolipram as potential therapy for multiple sclerosis and provoke the immediate initiation of clinical trials.

Interferon-gamma and host antimicrobial defense: current and future clinical applications

In the 1980s, substantive experimental data and emerging clinical results suggested that interferon-gamma (IFN-gamma), a T-cell-derived lymphokine with broad macrophage-activating effects, had considerable potential in the treatment of nonviral infections as a host defense-enhancing antimicrobial agent. During the past 6 years, the breadth of the experimental activity with IFN-gamma against nonviral pathogens has been expanded still further, and pilot studies and formal clinical trials using IFN-gamma have been undertaken in the treatment of patients both at risk for and with active infections. Thus far, IFN-gamma has been approved for use as prophylaxis in patients with chronic granulomatous disease. However, IFN-gamma also appears effective as adjunctive therapy for at least one disseminated intracellular infection (visceral leishmaniasis), and in conjunction with conventional therapy, may benefit patients with certain forms of cutaneous leishmaniasis, disseminated Mycobacterium avium complex infection, and lepromatous leprosy. Despite a rationale for its use, IFN-gamma has not yet been tested in tuberculosis or fungal or common bacterial infections nor sufficiently examined in the prevention and/or treatment of the opportunistic infections related to acquired immunodeficiency syndrome. IFN-gamma remains a promising host defense-enhancing cytokine with still unexplored clinical potential.

Induction of nitric oxide synthase in demyelinating regions of multiple sclerosis brains

The amount of messenger RNA encoding human inducible nitric oxide synthase and the presence and distribution of NADPH diaphorase were determined in tissue sections from multiple sclerosis (MS) and control brains. Levels of human nitric oxide synthase messenger RNA were markedly elevated in MS brains when compared to normal control brains. NADPH diaphorase activity, a histochemical stain reflecting nitric oxide synthase catalytic activity, was detected in reactive astrocytes in active demyelinating MS lesions and at the edge of chronic active demyelinating lesions. Control brains did not contain NADPH diaphorase-positive astrocytes. These results implicate the free radical nitric oxide in the pathogenesis of demyelinating MS lesions.

Gamma interferon activates a previously undescribed Ca2+ influx in T lymphocytes from patients with multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system. The etiology of the disease is still unknown. Activated T lymphocytes are considered essential in mediating the inflammatory process leading to demyelination in MS. They operate through a complex network of cytokines among which gamma interferon (gamma-IFN) plays a key role. Here we report that exposure to gamma-IFN of T lymphocytes from patients with MS activates, by a protein kinase C-mediated pathway, a previously undescribed gamma-IFN-activated Ca2+ influx, functionally coupled to the gamma-IFN receptor. The influx mainly expressed by CD4+ T lymphocytes, was found in 12 of 15 (80%) patients with clinically active MS and in 14 of 30 (46%) patients with stable MS. The influx was found in only 3 of 24 (12%) control patients and in none of the 15 healthy subjects studied. Our results document the appearance in MS lymphocytes of a gamma-IFN-activated, protein kinase C-dependent, Ca2+ influx that might be due to the expression of a new cation-specific plasmalemma channel. This finding suggests that at least part of gamma-IFN's contribution to the pathogenesis of MS is exerted through a Ca(2+)-dependent regulation of T lymphocyte activity.

Vascular cell adhesion molecule-1 modulation by tumor necrosis factor in experimental allergic encephalomyelitis

Anti-tumor necrosis factor (TNF) antibodies inhibit passively transferred experimental allergic encephalomyelitis (EAE) in SJL mice. The possibility that this occurs through interference in TNF's upregulation of endothelial cell adhesion molecules was investigated. Expression of both vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) on spinal cord vessels increased during EAE. The upregulation of VCAM-1 was markedly reduced or prevented by anti-TNF treatment. Leukocytic infiltration was 15-fold lower in anti-TNF-treated than diseased animals. Spinal cord endothelial expression of VCAM-1, though not ICAM-1 or fibronectin, positively correlated with the extent of T cell, B cell or monocyte infiltration in each animal.

Interferon beta for multiple sclerosis

OBJECTIVE

To introduce readers to the use of a new agent, interferon beta-1b (IFN beta ser), in the treatment of relapsing-remitting multiple sclerosis (RRMS). Therapeutic and economic issues surrounding IFN beta ser are discussed, as are its pharmacology, clinical efficacy, adverse effects, and dosage guidelines.

DATA SOURCES

A MEDLINE search was used to identify pertinent literature, including clinical trials and reviews.

STUDY SELECTIONS

All available trials were reviewed.

DATA EXTRACTION

Since trials evaluating subcutaneously administered interferon beta are sparse, clinical trials evaluating intrathecal IFN beta ser were included, as was toxicology information from the oncology population.

DATA SYNTHESIS

IFN beta ser has recently been approved by the Food and Drug Administration for the treatment of RRMS. Its exact mechanism of action is unknown, but it may downregulate interferon gamma (IFN gamma) production and the IFN gamma-stimulated major histocompatibility complex antigen expression, and/or augment T-suppressor cell function. Primary adverse effects include flu-like symptoms, fever, chills, myalgia, sweating, and injection-site reactions. Clinical efficacy has been investigated in 372 ambulatory patients with RRMS. IFN beta ser treatment resulted in a reduction in the annual exacerbation rate and a greater proportion of exacerbation-free patients. Burden of central nervous system disease was also significantly reduced in treated patients. However, no reductions were detected on the Scripps Neurologic Rating Scale or with confirmed endpoint scores on the Kurtzke Expanded Disability Status Scale. Although many questions remain concerning IFN beta ser's long-term efficacy, its benefits in patients with other types of multiple sclerosis (MS), and its effect on progression of disease and ultimate disability, IFN beta ser is the first treatment modality that has substantially altered the natural course of MS in a controlled clinical trial.

CONCLUSIONS

IFN beta ser is not a cure for MS, but it is well tolerated and patients with RRMS have shown significant improvements in exacerbation rates and burden of central nervous system disease. IFN beta ser should be considered a definite improvement in RRMS treatment, although many therapeutic issues remain unanswered. Additional clinical trials are needed.

Induction of autoimmune phenomena in patients with chronic hepatitis B treated with gamma-interferon

All interferons display antiviral properties, but gamma-interferon especially has an immunomodulatory effect and may induce autoimmune phenomena. Therefore the formation of autoantibodies was investigated in patients with chronic hepatitis B treated with gamma-interferon. Eleven patients (all HBs-Ag and HBe-Ag positive) were treated for 6 months with recombinant gamma-interferon. The following antibodies were tested: anti-nuclear antibodies, smooth muscle antibodies, anti-actin, anti-mitochondrial antibodies of subgroup anti-M2 and anti-M9 as well as naturally occurring antibodies, antibodies to liver-kidney microsomes, vascular endothelial cell antibodies, sarcolemmal antibodies, parietal cell antibodies, thyroglobulin antibodies and antibodies to laminin and keratin. All patients produced autoantibodies during therapy. The maximum antibody formation and the highest titres were observed in the period between the 3rd and 6th month after therapy began. The cumulative frequencies of the different antibody specificities were as follows: n = 6 anti-nuclear antibodies, n = 7 smooth muscle antibodies, n = 1 anti-actin, n = 12 antibodies to laminin or keratin, n = 6 endothelial cell antibodies/sarcolemmal antibodies, n = 6 anti-mitochondrial antibodies, n = 1 antibodies to liver-kidney microsomes, n = 2 thyroglobulin antibodies, n = 4 parietal cell antibodies. Antibodies persisted in six patients over a period of 3 months (two cases of parietal cell antibodies and one case of antibodies to liver-kidney microsomes) and were still detectable in three patients 6 months after therapy. In three patients new antibody formation occurred 1 month after therapy. So far, clinical signs of an autoimmune disorder have not appeared in any of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

A placebo-controlled trial of isoprinosine in patients with multiple sclerosis

Isoprinosine was used under double-blind, randomised, and placebo-controlled conditions in 52 patients with relapsing/remitting or progressive multiple sclerosis. All patients received pulsed treatment with methylprednisolone. There was no significant effect of treatment on clinical disability or the accumulation of MRI abnormalities, after correction of results for multiple comparisons. It is concluded that isoprinosine is not effective therapy for multiple sclerosis.

Influence of infection on exacerbations of multiple sclerosis

Exacerbations of multiple sclerosis (MS) are triggered by exogenous events, the best documented being viral upper respiratory infections (URIs), which can stimulate secretion of cytokines such as interferon-gamma (IFN-gamma) by immune cells. In conjunction with a recent clinical trial of systemic interferon-beta (IFN-beta) in relapsing-remitting MS, we studied the occurrence of viral infections and their correlation with MS attacks. Thirty patients kept daily logs, noting URI symptoms in themselves, family members, and co-workers. Patients were examined every 3 months, or whenever an attack of MS occurred, and were tested for antibodies to common upper respiratory pathogens. A strong correlation was found between MS attacks and URIs. There were 168 URIs in 2,792 patient-weeks, including 996 weeks at risk (the interval beginning 1 week before and ending 5 weeks after onset of URI symptoms) and 1,796 weeks not at risk. Nearly two-thirds of attacks occurred in periods at risk. Attack rates were 2.92 per year in weeks at risk compared to 1.16 per year in weeks not at risk, a significant difference (p < 0.001). High-dose interferon reduced the frequency of MS attacks, but had no effect on the number of URIs. Although a specific virus could not be incriminated, we concluded that URIs of presumed viral origin are an important trigger of MS attacks, and that treatment with IFN-beta reduces the attack rate, but not by preventing URIs. Rather, it may modulate responses to viral infection that would otherwise lead to immune activation and clinical symptoms.

A disturbance of interferon synthesis with the hyperproduction of unusual kinds of interferon can trigger autoimmune disease and play a pathogenetic role in AIDS: the removal of these interferons can be therapeutic

Disturbances of interferon synthesis with the hyperproduction of unusual kinds of interferons may be the initial step which triggers autoimmune disease through a chain of pathological reactions including the disturbances of several immunological and cytokine cascades. Prolonged circulation of this interferon may be a predictive marker of an autoimmune condition; the administration of interferons to animals or humans with autoimmune disease or an underlying or latent autoimmune condition can exacerbate or trigger the disease. Healthy people do not have interferon in their blood. This fundamental disturbance of interferon synthesis can result either from a genetic predisposition or from the influence of certain viruses (or viral particles) or both factors together. AIDS has many features similar to autoimmune disease, including the hyperproduction of aberrant interferon, a type with restricted anti-HIV activity, protectively induced by HIV to allow its continued replication and survival. This interferon stimulates the production of certain cytokines and autoantibodies which help unleash the potentially self-destructive powers of the immune system, bringing immunological chaos. In other words, while usual viruses induce normal interferon, which protects the cells against viral infection, HIV induces an abnormal, defective kind of interferon which ensures virus survival. Since there is no known effective method of destroying HIV directly, removing links in this chain of reactions could indirectly destroy HIV and possibly help restore immune functioning.(ABSTRACT TRUNCATED AT 250 WORDS)

Autologous enhancement by interferon of natural killer activity of human peripheral blood lymphocytes

The in vitro action of interferon (IFN)-alpha and IFN-gamma from six healthy donors and ten patients with multiple sclerosis (MS) on natural killer (INK) activity of peripheral blood lymphocytes (PBL) was studied in an autologous system. The NK activity of PBL was detected by a cytotoxic test using (3)H-uridine human erythromyeloblast K562 cells. Autologous IFN-alpha and IFN-gamma did not augment NK activity of PBL from healthy donors in vitro, whereas in samples from MS patients the IFNs strongly stimulated NK cell cytotoxic function. This stimulation suggests the existence of an inhibitor of regulatory IFN action, that is produced in healthy donors simultaneously with IFN in response to IFN induction, but which is lacking in commercial IFN preparations. The factor-containing supernatants from healthy donors reduced the stimulatory action of autologous IFNs in patients with MS almost until complete blockade. Because this inhibitor was absent in patients with MS, deficiency of an inhibitor of IFN regulatory action in MS could open the way to treatment of this compartment of the immune system.

A disturbance of interferon synthesis with the hyperproduction of unusual kinds of interferon can trigger autoimmune disease and play a pathogenetic role in AIDS: the removal of these interferons can be therapeutic

Disturbances of interferon synthesis with the hyperproduction of unusual kinds of interferons may be the initial step which triggers autoimmune disease through a concatenation of pathological reactions including the disturbance of several immunological and interferon cascades. This fundamental disturbance can result either from a genetic predisposition or from the influence of certain viruses (or viral particles) or both factors together. The administration of interferons to individuals with an underlying or latent autoimmune condition can exacerbate or trigger the disease. AIDS has many features similar to autoimmune disease, including the hyperproduction of aberrant interferon, a type with little or no anti-HIV activity, protectively induced by HIV to allow its continued replication and survival. In other words, while most viruses induce normal IFN which protects the cells against viral infection, HIV induces an abnormal, defective kind of IFN which insures viral survival. The neutralization of hyperproduced interferons by polyclonal or monoclonal antibody produced in mouse, or preferably, human hybridoma, removal via extracorporeal means, or the use of antagonists which diminish the production or biological activity of these interferons can be a therapeutic approach to the management of these chronic diseases. In addition, the extracorporeal removal of different kinds of interferons, autoantibodies, autoantigens and other substances from the organism in certain pathological conditions may be an effective and safe method of treatment for autoimmune diseases and AIDS.

Clinical trials of interferons in multiple sclerosis. What have we learned?

Although multiple sclerosis (MS) is generally believed to be an immune-mediated disease, conventional therapy with ACTH, corticosteroids, or immunosuppressive drugs is unsatisfactory. Aside from their unpredictable therapeutic effects, these agents are potentially hazardous and can only be given for short periods of time. There is an urgent need for less toxic yet effective immunotherapy, that that can be administered early in the disease and continued indefinitely. Clinical trials of the interferons (IFNs) have not only led to a promising new approach to treatment, but have also stimulated basic research in the immunological mechanisms of underlying disease activity. Administration of IFN-gamma promotes exacerbations of MS, whereas recombinant IFN-beta has been shown, in controlled clinical trials, to suppress them. Other ongoing studies are likely to provide further information about its long-term therapeutic value. More importantly, laboratory studies performed in conjunction with these clinical trials have provided fresh insights into the pathogenesis of MS by revealing immunoregulatory mechanisms in which endogenous IFN-gamma, TNF-alpha, and other cytokines appear to play central roles. The 'Decade of the Brain' may therefore see answers both to the therapeutic dilemma of MS, and to more basic questions about the function of IFNs and other cytokines in activation and regulation of the disease process.

Cytokine regulation of T-cell function: potential for therapeutic intervention

CD4+ T cells, via the cytokines that they produce, play a pivotal role in the induction and regulation of cell-mediated and humoral immunity. Recently it has become clear that the CD4+ T-cell population is heterogeneous and that distinct CD4+ T-cell subsets, defined by their cytokine repertoire, regulate cell-mediated and humoral immune responses. Protective responses to pathogens are dependent on activation of the appropriate TH subset accompanied by its characteristic set of immune effector functions. Evidence to date suggests that the cytokines produced by the TH cells themselves are important regulators of TH subset activation and differentiation. Here, Fiona Powrie and Robert Coffman discuss how manipulation of the levels of these cytokines can be used to alter the balance of TH cell subsets and illustrate some clinical situations where this may be beneficial.

Cytokine regulation of T-cell function: potential for therapeutic intervention

CD4+ T cells, via the cytokines that they produce, play a pivotal role in the induction and regulation of cell-mediated and humoral immunity. Recently it has become clear that the CD4+ T-cell population is heterogeneous and that distinct CD4+ T-cell subsets, defined by their cytokine repertoire, regulate cell-mediated and humoral immune responses. Protective responses to pathogens are dependent on activation of the appropriate TH subset accompanied by its characteristic set of immune effector functions. Evidence to date suggests that the cytokines produced by the TH cells themselves are important regulators of TH subset activation and differentiation. Fiona Powrie and Robert Coffman discuss how manipulation of the levels of these cytokines can be used to alter the balance of TH-cell subsets and illustrate some clinical situations where this may be beneficial.

Cytokine-regulated adhesion between encephalitogenic T lymphocytes and cerebrovascular endothelial cells

Adhesive interactions between murine cerebrovascular endothelial cells (EC) which comprise the blood-brain barrier (BBB) and myelin basic protein (MBP)-specific encephalitogenic T lymphocytes were investigated. Adhesion was assessed by measuring the percent attachment of 51Cr-labeled T cells to EC monolayers. The basal level adhesion (20-35%) was significantly up-regulated by treating EC with recombinant murine gamma interferon (IFN-gamma), interleukin-1 alpha (IL-1 alpha) and/or tumor necrosis factor-alpha (TNF alpha). The ability of these cytokines to modulate adhesion was dose- and time-dependent and could be detected as early as 1 h after treatment. The expression of intercellular adhesion molecule-1 (ICAM-1) by EC was examined by immunofluorescence staining and ELISA. Although all unstimulated EC cultures expressed ICAM-1, treatment of EC with the above cytokines dramatically up-regulated the level of ICAM-1 expression in a dose- and time-dependent fashion similar to that observed in the adhesion assays. Treatment of EC with transforming growth factor-beta 1 (TGF beta) down-regulated the level of T cell adhesion on untreated EC in a dose-dependent manner. Pretreatment of EC with TGF beta also partially inhibited the up-regulation of adhesion induced by IFN-gamma, IL-1 alpha and/or TNF alpha. TGF beta had no effect on the up-regulation of ICAM-1 expression induced by IFN-gamma, IL-1 alpha and/or TNF alpha. These results indicate that in addition to ICAM-1, other molecules may be involved in adhesion of encephalitogenic T cells to the EC comprising the cerebral vasculature.(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple sclerosis and prions

The etiology of Multiple Sclerosis (MS) is unknown. Existing epidemiologic data suggests that MS can be an infectious disease. MS used to be classified as one of the 'slow infections'--many of these are caused by prions. Prions are small, proteinaceous, infectious particles--distinguished from viruses by the absence of intrinsic nucleic acids. In a contrast to the 'classic' prional diseases (Kuru, Scrapie or Creutzfeldt-Jacob Disease) that in CNS affect primarily neurons, the 'target' cell in MS is an oligodendrocyte. This may explain differences in disease presentation. This paper presents a pathophysiological model of MS based on the assumption that MS is a prional disease. Processes leading to the demyelination in Multiple Sclerosis seem also to involve lymphocytes, astrocytes and macrophages as well as the interferon system.

T helper 1 (Th1) functional phenotype of human myelin basic protein-specific T lymphocytes

Multiple sclerosis (MS) is widely accepted as an autoimmune disease with myelin basic protein (MBP) a candidate autoantigen. In the current report, human T cell lines specific for an immunodominant region of MBP were shown to have a functional phenotype similar to T helper 1 (Th1) inflammatory cells of the mouse on the basis of their antigen-specific cytotoxic activity and production of interferon-gamma and lymphotoxin/tumor necrosis factor-alpha, but not interleukin-4. In experimental allergic encephalomyelitis (EAE), a proposed animal model for MS, MBP-specific T cell lines which mediate disease are of the Th1 subtype. Thus, MBP-specific T cells in humans exist which are phenotypically similar to MBP-specific encephalitogenic T cells in murine EAE.

The dynamics of multiple sclerosis. The Charcot Lecture

The history of our understanding of the pathogenesis and pathophysiology of multiple sclerosis are reviewed in the context of Charcot's contribution. The implications for treatment of the new knowledge gained from studies during life of pathology and pathogenesis (by MRI) and pathophysiology (by evoked potentials) are reviewed.

Lupus-like autoimmune disease induced by interferon therapy for myeloproliferative disorders

Symptoms of autoimmune disease were evaluated in 125 patients with chronic myelogenous leukemia (CML) and in 12 patients with essential thrombocythemia undergoing treatment with recombinant interferon (IFN)-alpha-2b plus/minus low-dose recombinant IFN-gamma. Twenty-seven of 137 patients (20%) developed rheumatoid symptoms. Furthermore, the incidence of antinuclear antibody (ANA) formation was studied. Elevated ANA titers were found in 5/19 (26%) of CML patients at the time of diagnosis and in 3/18 (17%) of patients treated with hydroxyurea or busulfan. During IFN treatment, 18 of 25 tested patients (72%) had elevated ANA titers. In 15 of these ANA-positive patients, clinical signs of autoimmune disease appeared. All these patients were under long-term IFN treatment and were in remission of disease. In three patients criteria for systemic lupus erythematosus were fulfilled. Severity of side effects had led to the discontinuation of IFN treatment in these patients. The data indicate that IFN-alpha and IFN-gamma can induce ANA associated with autoimmune disease in patients with myeloproliferative disorders.

Administration of interleukin-2 induces major histocompatibility complex class II expression on the biliary epithelial cells, possibly through endogenous interferon-gamma production

In various organ-specific autoimmune diseases, aberrant expression of major histocompatibility complex class II antigens on each target epithelial cell has been reported. Some researchers have attempted to link this phenomenon to the antigen-presenting capacity and the induction of autoimmunity, whereas others think it might serve as a peripheral mechanism for the induction and the maintenance of self-tolerance in autoreactive T cells. In this study, we showed that intraperitoneal administration of interleukin-2 (1.2 x 10(6) IU/kg) to 4-wk-old male BALB/c mice for 35 consecutive days induced lymphocyte infiltration around bile ducts in the liver and major histocompatibility complex class II expression on biliary epithelial cells, which was immunoelectron microscopically confined to the luminal cell surface. Immunohistochemically, lymphocytes accumulating around bile ducts were mainly T cells, positive for CD3, L3T4 and H-2 class II molecules, and a few of them were positive for Lyt-2 and negative for immunoglobulin. Half of the infiltrates were positive for asialo GM1, and one-third was positive for interferon-gamma. Interferon-gamma-positive, L3T4-positive cells were detected in mirror sections. However, neither the destruction of biliary epithelial cells nor the presence of granulomas was observed. Autoantibodies were serologically undetectable. The existence of interferon-gamma-positive cells in the lesion and the fact that intravenous administration of anti-interferon-gamma twice a week completely inhibited the lymphocyte infiltration and the major histocompatibility complex class II expression on biliary epithelial cells suggested that these changes were induced through endogenous interferon-gamma production.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum factors responsible for unusual induction of plasminogen activator activity in tuberous sclerosis

Peripheral blood lymphocytes derived from tuberous sclerosis (TS) patients showed unusually high levels of plasminogen activator (PA) activity after treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Serum obtained from peripheral blood of TS patients also enhanced the PA activity level when normal control lymphocytes were incubated with the serum prior to MNNG treatment. Factors exhibiting the enhancing activity were eluted with a solution of about 0.70 M KCl on dye-ligand chromatography, which were inhibited on incubation with an anti-human interferon (HuIFN)-beta antibody, but not with anti-HuIFN-alpha or anti-HuIFN-gamma antibodies. Unlike in the case of HuIFN-beta, the eluted samples did not possess antiviral or anticellular activity. Thus, it seems likely that serum from TS patients contains factors which are responsible for the unusual PA induction and which have a similar epitope to HuIFN-beta.

Monocytes in active multiple sclerosis: intact regulation of HLA-DR density in vitro despite decreased HLA-DR density in vivo

HLA-DR expression on circulating monocytes varies as a function of disease activity in patients with multiple sclerosis (MS), a putative immunopathological demyelinating disorder. Specifically, monocytes isolated from subjects with active MS exhibit reduced HLA-DR antigen density, and immunoregulatory aberrations such as impaired T lymphocyte-mediated suppression correlate strongly with this quantitative defect. To address the mechanism underlying this phenomenon, we compared in vitro regulation of HLA-DR by interferon beta (IFN beta), interferon gamma (IFN gamma), and lipopolysaccharide (LPS) in monocytes from patients with stable and active MS and normal individuals. Interferon-gamma and LPS enhanced monocyte expression of HLA-DR equally in both MS patient groups, suggesting that underexpression of HLA-DR in active MS was not explained by impaired in vivo monocyte responsiveness. Furthermore, interferon regulation of HLA-DR in normals and stable MS subjects was indistinguishable, indicating that aberrant interferon-mediated regulation of class II major histocompatibility complex (MHC) on circulating monocytes does not appear to be a characteristic of the MS disease state.

Effect of anti-interferon-gamma and anti-interleukin-2 monoclonal antibody treatment on the development of actively and passively induced experimental allergic encephalomyelitis in the SJL/J mouse

SJL/J mice challenged with myelin basic protein (MBP) in complete Freund's adjuvant (CFA) developed only mild chronic-relapsing experimental allergic encephalomyelitis (EAE) with very low incidence. However, treatment of challenged mice with anti-interferon-gamma (IFN-gamma) monoclonal antibody (mAb) determined severe disease in all cases. Similarly, in passive EAE, the addition of anti-IFN-gamma to the in vitro MBP-activated cells at the time of transfer led to significant disease exacerbation in all recipients. The disease enhancing effect was observed only when the mAb was given at the time of active challenge or of passive transfer, but not at later times. Anti-interleukin-2 (IL-2) antibody had only a marginal effect in the active induction, but drastically reduced the manifestations of passive EAE, even when mixed with a disease-enhancing dose of anti-IFN-gamma. These findings support the notion that IL-2 is required for disease induction whereas IFN-gamma plays a disease-limiting role early in the development of EAE.

Transgenic mouse model for central nervous system demyelination

A common feature of demyelinating diseases such as multiple sclerosis in humans and experimental autoimmune encephalomyelitis in rodents is the marked elevation in the expression of the major histocompatibility complex (MHC) antigens in the involved sites. By specific targeting of a syngeneic MHC class I gene to oligodendrocytes, we have generated transgenic mice which not only exhibit severe involuntary tremors and develop tonic seizures but also show extensive demyelination in both the brain and the spinal cord. The fact that demyelination in these mice occurs in the absence of immune infiltration dismisses an autoimmune involvement but suggests that the MHC class I antigens play a direct role in inducing disease. Our findings lend support to the possibility that demyelinating diseases are induced by infectious agents such as viruses which can either directly activate MHC gene expression in oligodendroglia or indirectly activate expression through the release by reactive T cells of gamma interferon in the brain.

Human tumor necrosis factor-alpha augments experimental allergic encephalomyelitis in rats

The effect of human recombinant tumor necrosis factor-alpha (TNF) on experimental allergic encephalomyelitis (EAE) was studied in Lewis rats. TNF was injected intraperitoneally at a daily dose of 1 x 10(3) or 2 x 10(4) U for 8 consecutive days from one day after sensitization with guinea-pig spinal cord in complete Freund's adjuvant. All rats in the control group developed clinical signs of EAE but recovered within 8 days after the onset. Injections of 2 x 10(4) U/day of TNF resulted in a significant prolongation of clinical EAE: clinical signs were sustained for up to 15 days after onset. Histologically, rats receiving 2 x 10(4) U/day of TNF had more severe cellular infiltrations in the spinal cord than controls. The augmentation of EAE was not found in rats receiving 1 x 10(3) U/day of TNF or TNF that had been neutralized with anti-TNF monoclonal antibody.

Transgenic mouse model for central nervous system demyelination

A common feature of demyelinating diseases such as multiple sclerosis in humans and experimental autoimmune encephalomyelitis in rodents is the marked elevation in the expression of the major histocompatibility complex (MHC) antigens in the involved sites. By specific targeting of a syngeneic MHC class I gene to oligodendrocytes, we have generated transgenic mice which not only exhibit severe involuntary tremors and develop tonic seizures but also show extensive demyelination in both the brain and the spinal cord. The fact that demyelination in these mice occurs in the absence of immune infiltration dismisses an autoimmune involvement but suggests that the MHC class I antigens play a direct role in inducing disease. Our findings lend support to the possibility that demyelinating diseases are induced by infectious agents such as viruses which can either directly activate MHC gene expression in oligodendroglia or indirectly activate expression through the release by reactive T cells of gamma interferon in the brain.

Dysmyelination in transgenic mice resulting from expression of class I histocompatibility molecules in oligodendrocytes

Major histocompatibility complex (MHC) molecules are not normally expressed in the central nervous system (CNS). However, aberrant expression has been observed in multiple sclerosis lesions and could contribute to the destruction of myelin or the myelinating cells known as oligodendrocytes. The mechanism of cell damage associated with aberrant MHC molecule expression is unclear: for example, overexpression of class I and class II MHC molecules in pancreatic beta cells in transgenic mice leads to nonimmune destruction of the cells and insulin-dependent diabetes mellitus. We have generated transgenic mice that express class I H-2Kb MHC molecules, under the control of the myelin basic protein promoter, specifically in oligodendrocytes. Homozygous transgenic mice have a shivering phenotype, develop tonic seizures and die at 15-22 days. This phenotype, which we term 'wonky', is due to hypomyelination in the CNS, and not to involvement of the immune system. The primary defect appears to be a shortage of myelinating oligodendrocytes resulting from overexpression of the class I MHC molecules.

Interleukin-1-like activity in normal rat skin after in vivo treatment with interferon-gamma

The influence of interferon-gamma (IFN-gamma) on immune responses is still ambiguous. We have investigated whether IFN-gamma influences the constitutive interleukin-1 (IL-1)-like activity in normal rat skin because IL-1 is a regulatory cytokine in immune responses. Rats were injected intradermally into both ears with different doses of rat recombinant IFN-gamma (10(3)-10(5) U), and control animals were given phosphate-buffered saline (PBS). The animals were killed at different times and the ears were cut off at the bases. The biologic activity of the IFN-gamma was verified by immunohistochemistry on injected ears, showing a time- and dose-dependent induction of major histocompatibility complex class II antigens on the keratinocytes. Aqueous extracts of homogenized ear skin were tested for IL-1-like activity in a mouse thymocyte bioassay. No major effects of IFN-gamma on the constitutive IL-1-like activity in the rat skin were found; at 6 h there was a slight reduction and at 72 h an increase in IL-1 bioactivity in extracts from IFN-gamma (10(5) U)-injected animals compared with PBS-treated controls (p less than 0.05). We conclude that the regulation of immune responses in the rat skin by IFN-gamma is less likely to be mediated via changes in the IL-1-like activity.

Chronic effects of gamma-interferon on quinolinic acid and indoleamine-2,3-dioxygenase in brain of C57BL6 mice

Chronic infections are associated with increased concentrations of the neuroactive kynurenine pathway metabolite, quinolinic acid (QUIN), in blood and cerebrospinal fluid. In the present study, repeated injections of gamma-interferon (5000 IU, every 3 days for 39 days) to C57BL6 mice were associated with persistent activation of indoleamine-2,3-dioxygenase (IDO), the first enzyme of the kynurenine pathway, in lung and brain, sustained increases in brain QUIN concentration and increases in plasma L-kynurenine and QUIN levels. Mice chronically treated with gamma-interferon offer an animal model to investigate the effects of sustained immune stimulation on kynurenine pathway metabolism.