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

Understanding Multiple Sclerosis Pathophysiology and Current Disease-Modifying Therapies: A Review of Unaddressed Aspects

Multiple sclerosis (MS) is a complex autoimmune disorder of the central nervous system (CNS) with an unknown etiology and pathophysiology that is not completely understood. Although great strides have been made in developing disease-modifying therapies (DMTs) that have significantly improved the quality of life for MS patients, these treatments do not entirely prevent disease progression or relapse. Identifying the unaddressed pathophysiological aspects of MS and developing targeted therapies to fill in these gaps are essential in providing long-term relief for patients. Recent research has uncovered some aspects of MS that remain outside the scope of available DMTs, and as such, yield only limited benefits. Despite most MS pathophysiology being targeted by DMTs, many patients still experience disease progression or relapse, indicating that a more detailed understanding is necessary. Thus, this literature review seeks to explore the known aspects of MS pathophysiology, identify the gaps in present DMTs, and explain why current treatments cannot entirely arrest MS progression.

A Double-Edged Sword-Cardiovascular Concerns of Potential Anti-COVID-19 Drugs

Coronavirus disease 2019 (COVID-19) is a pandemic infection caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). COVID-19 significantly affects multiple systems including the cardiovascular system. Most importantly, in addition to the direct injury from the virus per se, the subsequent cytokine storm, an overproduction of immune cells and their activating compounds, causes devastating damage. To date, emerging anti-SARS-CoV-2 treatments are warranted to control epidemics. Several candidate drugs have been screened and are currently under investigation. These primarily include antiviral regimens and immunomodulatory regimens. However, beyond the anti-SARS-CoV-2 effects, these drugs may also have risks to the cardiovascular system, especially altering cardiac conduction. Herein, we review the cardiovascular risks of potential anti-COVID-19 drugs.

IL-27 mediates the response to IFN-β therapy in multiple sclerosis patients by inhibiting Th17 cells

Interferon (IFN)-β is a commonly used therapy for relapsing remitting multiple sclerosis (RRMS). However its protective mechanism is still unclear and the failure of many patients to respond has not been explained. We have found that IFN-β suppressed IL-23 and IL-1β production and increased IL-10 production by human dendritic cells (DC) activated with the TLR2 and dectin-1 agonist zymosan. Furthermore, IFN-β impaired the ability of DC to promote IL-17 production by CD4(+) T cells, but did not affect IFN-γ production. IFN-β induced IL-27 expression by DC, and neutralisation of IL-27 abrogated the suppressive effects of IFN-β on zymosan-induced IL-1 and IL-23 production and the generation of Th17 cells in vitro. Complementary in vivo studies in a mouse model showed that treatment with IFN-β enhanced expression of IL-27, and reduced IL-17 in the CNS and periphery and attenuated the clinical signs of experimental autoimmune encephalomyelitis (EAE). In addition, the significant suppressive effect of IFN-β on the ability of DC to promote Th17 cells was lost in cells from IL-27 receptor deficient mice. Finally, we showed that PBMC from non-responder RRMS patients produced significantly less IL-27 in response to IFN-β than patients who responded to IFN-β therapy. Our findings suggest that IFN-β mediates its therapeutic effects in MS at least in part via the induction of IL-27, and that IL-27 may represent an alternative therapy for MS patients that do not respond to IFN-β.

PEGylated interferon beta-1a: meeting an unmet medical need in the treatment of relapsing multiple sclerosis

Multiple sclerosis is a chronic autoimmune disease of the central nervous system for which a number of disease-modifying therapies are available, including interferon beta (Avonex®, Rebif®, and Betaseron/Betaferon®), glatiramer acetate (Copaxone®), and an anti-VLA4 monoclonal antibody (Tysabri®). Despite the availability and efficacy of these protein and peptide drugs, there remains a significant number of patients who are untreated, including those with relatively mild disease who choose not to initiate therapy, those wary of injections or potential adverse events associated with therapy, and those who have stopped therapy due to perceived lack of efficacy. Since these drugs have side effects that may affect a patient's decision to initiate and to remain on treatment, there is a need to provide a therapy that is safe and efficacious but that requires a reduced dosing frequency and hence a concomitant reduction in the frequency of side effects. Here we describe the development of a PEGylated form of interferon beta-1a that is currently being tested in a multicenter, randomized, double-blind, parallel-group, placebo-controlled study in relapsing multiple sclerosis patients, with the aim of determining the safety and efficacy of 125 microg administered via the subcutaneous route every 2 or 4 weeks.

IFN-beta inhibits dendritic cell migration through STAT-1-mediated transcriptional suppression of CCR7 and matrix metalloproteinase 9

IFN-beta is an approved therapeutic option for the treatment of multiple sclerosis. The molecular mechanisms underlying the effects of IFN-beta in multiple sclerosis are not fully understood. Migration of dendritic cells (DCs) from the inflammatory site to draining lymph nodes for Ag presentation and activation of naive T cells and to the CNS for reactivation of encephalitogenic T cells requires CCR7 and matrix metalloproteinase (MMP)-9 expression. This article reports for the first time that IFN-beta inhibits CCR7 expression and MMP-9 production in mature DCs and reduces their migratory capacity. The effect of IFN-beta is mediated through STAT-1. In vivo treatment with IFN-beta results in lower numbers of DCs migrating to the draining lymph node following exposure to FITC and in reduced expression of CCR7 and MMP-9 in splenic CD11c(+) DCs following LPS administration. IFN-beta and IFN-gamma share the same properties in terms of their effects on CCR7, MMP-9, and DC migration, but they have opposite effects on IL-12 production. In addition, IFN-beta-treated DCs have a significantly reduced capacity for activating CD4(+) T cells and generating IFN-gamma-producing Th1 cells. The suppression of mature DC migration through negative regulation of CCR7 and MMP-9 expression represents a novel mechanism for the therapeutic effect of IFN-beta.

Interferon beta induces mature dendritic cell apoptosis through caspase-11/caspase-3 activation

Although interferon beta (IFNbeta) decreases relapse rate and disease activity in multiple sclerosis (MS), the mechanisms involved have not been elucidated. The present study is the first report on the apoptotic effect of IFNbeta in mature, but not immature, myeloid dendritic cells (DCs). Both exogenous IFNbeta added to DCs matured through exposure to proinflammatory cytokines and endogenous IFNbeta secreted after lipopolysaccharide stimulation induced DC cell death. Apoptosis of mature DCs required both NF-kappaB and STAT-1 activation, and was mediated through the induction of caspase-11 expression and activation of caspase-3. In vivo, we observed increased caspase-11 expression and a significant decrease in the number of splenic DCs after lipopolysaccharide administration in wt but not in STAT-1-deficient mice. Since mature DCs are major contributors to the inflammatory response and essential partners in the induction of adaptive immunity, IFNbeta-dependent elimination of activated DCs could play an essential role in re-establishing homeostasis, and might represent a new molecular mechanism for the therapeutic effect of IFNbeta in MS.

IL-17 signaling-independent central nervous system autoimmunity is negatively regulated by TGF-beta

Recent studies have established an important role of Th17 in induction of autoimmune diseases. We have found that although IL-17 receptor A (IL-17RA)(-/-) mice were resistant to experimental autoimmune encephalomyelitis, a small number of them developed milder clinical signs of this autoimmune disease. In addition, blockade of TGF-beta in IL-17RA(-/-) mice resulted in much more severe clinical signs of experimental autoimmune encephalomyelitis and significantly increased parenchymal lymphocyte infiltration in the CNS. Furthermore, the number of autoreactive Th1 cells was greatly increased in the inflamed spinal cord of IL-17RA(-/-) mice. These data support a role of IL-17RA-independent mechanisms in causing autoimmunity and its regulation by TGF-beta.

The flavones luteolin and apigenin inhibit in vitro antigen-specific proliferation and interferon-gamma production by murine and human autoimmune T cells

Plant-derived flavonoids are inhibitors of various intracellular processes, notably phosphorylation pathways, and potential inhibitors of cellular autoimmunity. In this study, the inhibiting effects of various flavonoids on antigen-specific proliferation and interferon-gamma (IFN-gamma) production by human and murine autoreactive T cells were evaluated in vitro. T-cell responses were evaluated for the human autoantigen alpha B-crystallin, a candidate autoantigen in multiple sclerosis, and for the murine encephalitogen proteolipid protein peptide PLP (139-151). The flavones apigenin and luteolin were found to be strong inhibitors of both murine and human T-cell responses while fisitin, quercitin, morin and hesperitin, members of the subclasses of flavonoles and flavanones, were ineffective. Antigen-specific IFN-gamma production was reduced more effectively by flavones than T-cell proliferation, suggesting that the intracellular pathway for IFN-gamma production in T cells is particularly sensitive to flavone inhibition. These results indicate that flavones but not flavanoles or flavanones are effective inhibitors of the potentially pathogenic function of autoreactive T cells. The effects of flavones were the same for human and murine autoreactive T cells, stressing the usefulness of animal models of autoimmunity for further studies on the effects of flavonones on autoimmune diseases.

Signaling through JAK2-STAT5 pathway is essential for IL-3-induced activation of microglia

Microglia, the resident macrophage of the brain, mediates immune and inflammatory responses in the central nervous system (CNS). Activation of microglia and secretion of inflammatory cytokines associate with the pathogenesis of CNS diseases, including multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease, prion disease, and AIDS dementia. Microbial pathogens, cytokines, chemokines, and costimulatory molecules are potent inducers of microglial activation in the CNS. Signaling through its receptor, IL-3 induces the activation of JAK-STAT and MAP kinase pathways in microglial cells. In this study, we found that in vitro treatment of EOC-20 microglial cells with tyrphostin AG490 blocked IL-3-induced tyrosine phosphorylation of JAK2, STAT5A, and STAT5B signaling proteins. Stable transfection of EOC-20 cells with a dominant negative JAK2 mutant also blocked IL-3-induced tyrosine phosphorylation of JAK2, STAT5A, and STAT5B in microglia. The blockade of JAK2-STAT5 pathway resulted in a decrease in IL-3-induced proliferation and expression of CD40 and major histocompatibility complex class II molecules in microglia. These findings highlight the fact that JAK2-STAT5 signaling pathway plays a critical role in mediating IL-3-induced activation of microglia.

An immunomodulatory GpG oligonucleotide for the treatment of autoimmunity via the innate and adaptive immune systems

Bacterial DNA and immunostimulatory CpG oligodeoxynucleotides (ODNs) activate the innate immune system to produce proinflammatory cytokines. Shown to be potent Th1-like adjuvants, stimulatory CpG motifs are currently used as effective therapeutic vaccines for various animal models of infectious diseases, tumors, allergies, and autoimmune diseases. In this study, we show that the application of an immunomodulatory GpG ODN, with a single base switch from CpG to GpG, can effectively inhibit the activation of Th1 T cells associated with autoimmune disease. Moreover, this immunomodulatory GpG ODN suppresses the severity of experimental autoimmune encephalomyelitis in mice, a prototypic Th1-mediated animal disease model for multiple sclerosis.

IFN-beta gene transfer into the central nervous system using bone marrow cells as a delivery system

The peripheral delivery of interferon-beta (IFN-beta) for the treatment of central nervous system (CNS) diseases is only partially effective because of the blood-brain barrier (BBB). To circumvent this problem, we evaluated the feasibility of genetically altering bone marrow cells ex vivo and using them as vehicles to transfer the IFN-beta cDNA into the mouse CNS. An IFN-beta retroviral expression vector (pLXSN-IFNbeta) was used to stably transfect PA317 cells. The supernatant from these producer cells, which expressed IFN-beta mRNA and protein, were used to infect bone marrow cells. When transplanted into irradiated mice, IFN-beta-engineered marrow cells accessed the CNS and expressed IFN-beta mRNA and protein. Marrow cells transduced with a control neomycin vector entered the brain and expressed the neomycin but not the IFN-beta gene. In the CNS, IFN-beta delivered by marrow cells induced the mRNA expression of 2',5'-oligoadenylate synthetase (2',5'-OAS), indicating biologic activity. Our findings demonstrating that bone marrow cells can serve as a delivery system for IFN-beta cDNA into the CNS could have implications for the treatment of neurologic disorders, such as multiple sclerosis (MS), viral encephalitis, and brain tumors.

Factors modifying the migration of lymphocytes across the blood-brain barrier

Characterising the factors that control the entry of leucocytes into tissue in response to inflammatory or microbial insult continues to generate considerable interest. Of all the tissues studied it is probably that of the CNS which is the most fascinating because of the specialised properties of its blood vessel walls, which constitute the blood-brain barrier (BBB). In health, very few leucocytes penetrate the BBB but in disorders such as MS the barrier becomes compromised with the result that there is an intense infiltration of the CNS by T lymphocytes whose subsequent activity appears to underlie the onset and progression of disease. The purpose of this article is to summarise and assess recent literature pertaining to how lymphocytes bind to cerebral endothelial cells, migrate across the blood vessel walls and enter the CNS parenchyma. Particular emphasis is devoted to the cellular and molecular aspects of these events and addressing the questions of whether certain subsets of circulating T lymphocytes are more favourably disposed than others to CNS infiltration and whether entry is dependent upon the initial expression of distinct groups of adhesion molecules and upon the generation of chemotactic factors. This article also focuses upon identifying the key stages of lymphocyte migration across the BBB and their susceptibility to antagonism by therapeutic agents. It is intended that the review will provide a useful source of information and offer additional insights into the mechanisms controlling lymphocyte passage across the BBB during pathological disturbance.

Amelioration of CR-EAE with lisofylline: effects on mRNA levels of IL-12 and IFN-gamma in the CNS

CR-EAE is a Th1-mediated inflammatory autoimmune demyelinating disease of the CNS and serves as a model of human multiple sclerosis. Our previous studies have shown the protective effect of orally administered lisofylline in the prevention of active and passively induced acute EAE. In our present studies we have examined the efficacy and mechanism of action of lisofylline on CR-EAE. Lisofylline decreased the number and severity of paralytic attacks in mice with relapsing EAE. The reduction of clinical disease correlated with decreased levels of mRNA levels of IFN-gamma but not of mRNA levels of IL-12. These studies suggest that lisofylline may be an effective therapeutic for established Th1 mediated autoimmune disease and that it acts by blocking IL-12R signaling and not IL-12 production in vivo.

[Interferon beta 1-a in multiple sclerosis: 1-year experience in 62 patients]

We report the results of a trial of interferon beta 1-a in 62 ambulatory patients with relapsing-remitting multiple sclerosis. Entry criteria included EDSS of 0 to 5.5 and at least two exacerbations in the previous 2 years. The patients received 3 million international units by subcutaneous injections three times a week. The end points were differences in exacerbation rate and treatment effect on disease progression. The annual exacerbation rate for patients that did not take the interferon beta 1-a was 1.32 and for the patients under medication 0.63. The EDSS score in patients that did not take the mediaction was 4.7 and 2.0 for the patients with interferon beta 1-a. Interferon beta 1-a was well tolerated and 85% of patients completed 1 year treatment.

Alterations in cytokine but not chemokine mRNA expression during three distinct Theiler's virus infections

DA, GDVII and H101 are neurovirulent strains of Theiler's murine encephalomyelitis virus that cause very different neuropathology and CNS disease when inoculated into SJL/J mice. DA virus causes a chronic demyelinating disease, GDVII virus causes an acute fatal polioencephalomyelitis, and H101 virus causes an acute pachymeningitis with hydrocephalus. Performing RNase protection assays, we detected the same pattern of chemokine (RANTES, MCP-1, IP-10, MIP-1beta, MIP-1alpha and MIP-2) mRNA expression in brain and spinal cord during all three infections. In contrast, IFN-beta and IL-6 mRNA were highly expressed only in GDVII virus infection, whereas high levels of LT-alpha mRNA were only found during DA virus infection. Our study demonstrates that proinflammatory cytokines are involved in the neuropathogenesis of CNS disease and modulate the acute and chronic process underlying different pathologic features of disease.

Amelioration of collagen-induced arthritis and suppression of interferon-gamma, interleukin-12, and tumor necrosis factor alpha production by interferon-beta gene therapy

OBJECTIVE

To investigate the therapeutic effects and possible mechanisms of action of constitutive expression of interferon-beta (IFNbeta) by syngeneic fibroblasts from DBA/1 mice in the collagen-induced arthritis (CIA) model.

METHODS

Immortalized embryonic DBA/1 fibroblasts were infected with a retrovirus expressing murine IFNbeta. IFNbeta-expressing fibroblasts were then implanted intraperitoneally into mice immunized with bovine type II collagen. The effect of IFNbeta on paw swelling, anticollagen antibody levels, IgG1/IgG2a isotype profiles, arthritis score, histologic joint damage, and cytokine secretion from lymph node cells and from bone marrow-derived macrophages was assessed.

RESULTS

A single injection of IFNbeta-secreting fibroblasts was sufficient to prevent arthritis or to ameliorate existing disease. Thus, IFNbeta reduced the clinical score and paw swelling irrespective of whether the injection was administered before or after disease onset in treated mice, compared with that in the untreated control group (P < 0.05). Histologic findings in the IFNbeta-treated mice were markedly less severe than in the control group (P < 0.001). This effect was accompanied by a decrease in total anticollagen IgG levels, a decrease in anticollagen IgG2a, and an increase in IgG1. In vitro, supernatants from these engineered fibroblasts inhibited collagen-induced interferon-gamma secretion from lymph node cells, and reduced the levels of tumor necrosis factor alpha and interleukin-12 produced by lipopolysaccharide/IFNgamma-treated bone marrow-derived macrophages. This effect was specific, since it was reversed with anti-IFNbeta polyclonal antibodies.

CONCLUSION

These results indicate that IFNbeta, which is currently used as a treatment for relapsing, remitting multiple sclerosis, is a potent immunomodulatory and antiinflammatory cytokine in CIA and should be considered for the treatment of rheumatoid arthritis.

Prevention of Experimental Allergic Encephalomyelitis via Inhibition of IL-12 Signaling and IL-12-Mediated Th1 Differentiation: An Effect of the Novel Anti-Inflammatory Drug Lisofylline

Experimental allergic encephalomyelitis (EAE) is an inflammatory, CD4+ Th1-mediated autoimmune disease, which serves as a model for multiple sclerosis. We examined the effect of a novel anti-inflammatory drug, lisofylline (LSF), on EAE induced either by injection of mouse spinal cord homogenate or following transfer of myelin basic protein-reactive T cells. Orally administered LSF significantly inhibited EAE in both cases, decreasing peak clinical scores by &gt;70% and &gt;80%, respectively. In addition, analysis of representative spinal cord sections from LSF-treated mice showed complete lack of demyelination and lymphocyte infiltration. The reduction in EAE correlated with the inhibition of Th1 differentiation by LSF in vivo, as indicated by a reduction in T cell IFN-γ production ex vivo after Ag restimulation. The inhibition of Th1 differentiation in vivo is consistent with a block in IL-12 receptor signaling, because LSF blocked IL-12-driven Th1 differentiation and T cell proliferation in vitro, yet had no effect on IL-12 secretion from APCs ex vivo or in vitro.

Glucocorticosteroid therapy for multiple sclerosis: a critical review

Controversy remains as to the efficacy, route of administration and dose of glucocorticosteroid (GCS) in multiple sclerosis (MS) therapy. With the recent approval of new disease modifying treatments and increasing interest in cost-benefit assessments, it is timely to critically consider their role in MS therapeutics. In this paper we review our current understanding of the cellular and molecular mechanisms of action of GCS as they relate to the postulated pathophysiology of MS. We also critically review the use of glucocorticosteroid therapy to: (1) improve recovery from exacerbations of MS, (2) delay the onset of MS in patients who experience a first episode of monosymptomatic optic neuritis, and (3) delay the time to onset of sustained progression of disability in patients with clinically definite MS.

Stressor-induced alteration of cytokine production in multiple sclerosis patients and controls

OBJECTIVE

We administered an acute psychological stressor to multiple sclerosis (MS) patients and normal controls to determine whether differences in subjective and physiological responses to stress may underlie the susceptibility of MS patients to stress-related exacerbations.

METHOD

Twenty-five MS patients (18 female, 7 male) and 25 age- and gender-matched controls participated in the study. They were asked to give a 5-minute videotaped speech defending themselves in a hypothetical scenario in which they were wrongly accused of stealing. Subjective and autonomic responses were monitored, and blood was sampled at baseline, 5, 20, and 60 minutes after the stressor to assess mitogen-stimulated production of interleukin-1beta(IL-1beta), interleukin-4 (IL-4), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma).

RESULTS

MS patients and controls demonstrated similar subjective and physiological responses to the stressor that were independent of gender, mood, and disability status. The macrophage-derived cytokines IL-1beta and TNF-alpha were increased during the stressor, and remained elevated through 60 minutes. Th1 lymphocyte-derived IFN-gamma production also was increased at 5 and 60 minutes relative to baseline; however, there was no change in the Th2 lymphocyte-derived cytokine IL-4.

CONCLUSIONS

These results favor the hypothesis that MS patients do not differ in stress response from normal controls; however, psychological stress may enhance cellular immune responses that would be potentially harmful to MS patients.

Interleukin-6 functions in autoimmune encephalomyelitis: a study in gene-targeted mice

The encephalitogenic peptide pMOG 35-55 from the myelin oligodendrocyte glycoprotein was used to induce experimental autoimmune encephalomyelitis (EAE) in H-2b mice with the interleukin-6 (IL-6) gene intact or disrupted. The IL-6+/+ mice developed a chronic form of EAE ascending paralysis, whereas the IL-6-/- mice were resistant to the disease. Injections of recombinant IL-6 following pMOG immunization induced severe disease in the IL-6-/- mice. Histological examination of brain and spinal cord sections showed that the perivascular infiltration of inflammatory cells evident in IL-6+/+ mice was absent in the IL-6-/- animals and could be restored by exogenous IL-6 administration. Anti-MOG antibody levels were much lower in the IL-6-/- mice, but were not restored to high levels by IL-6 injections which elicited the development of pMOG 35-55-induced EAE. T lymphocytes reactive to the pMOG antigen were recovered from lymph nodes of both types of mice and Tcell lines could be established from both. Adoptive transfer of Tcell lines from IL-6+/+ mice induced EAE in the mice with the intact IL-6 gene but less in the IL-6-deficient mice, indicating that the resistant phenotype cannot be explained solely by lack of encephalitogenic Tcells. The absence of cell infiltrates in the brain and spinal cords of IL-6-/- mice upon adoptive transfer of the pathogenic Tcells from IL-6+/+ mice is consistent with a function of IL-6 in the local perivascular inflammatory process.

Cytokines, signal transduction, and inflammatory demyelination: review and hypothesis

The mechanism of focal demyelination in multiple sclerosis has been a long-standing enigma of this disorder. Cytokines, a diverse family of signalling molecules, are viewed as potential mediators of the process based on clinical observations and studies with animal models and tissue/cell culture systems. Myelin and oligodendrocyte (OL) destruction occur in cultured preparations subjected to cytokines such as tumor necrosis factor-alpha (TNF alpha) and lymphotoxin (LT). Many studies have shown these and other cytokines to be elevated at lesion sites and in the CSF of multiple sclerosis (MS) patients, with similar findings in animal models. Some variability in the nature of MS lesion formation has been reported, both OLs and myelin being primary targets. To account for myelin destruction in the presence of apparently functional OLs we hypothesize that cytokines such as TNF alpha and LT alpha contribute to myelin damage through triggering of specific reactions within the myelin sheath. We further propose that neutral sphingomyelinase (SMase) is one such enzyme, two forms of which have been detected in purified myelin. An additional event is accumulation of cholesterol ester, apparently a downstream consequence of cytokine-induced SMase. The resulting lipid changes are viewed as potentially destabilizing to myelin, which may render it more vulnerable to attack by invading and resident phagocytes.

Immunomodulating therapeutic approaches for multiple sclerosis

In this review we delineate the rationale for immunotherapy in multiple sclerosis and describe the various levels at which immune intervention, according to a modern model of the immune system organization, is feasible. Current and future immunosuppressive and immunomodulating therapeutic approaches at the level of antigen presentation and at the lymphocyte and cytokine network levels are discussed.

Cytokine mRNA expression in CSF and peripheral blood mononuclear cells in multiple sclerosis: detection by RT-PCR without in vitro stimulation

We amplified the mRNA for cytokines in peripheral blood mononuclear cells (PBMC) and cerebrospinal fluid (CSF) cells from 18 multiple sclerosis (MS) patients and 21 other neurological patients, using reverse transcription polymerase chain reaction (RT-PCR). A radioactive hybridization of the amplified DNA allowed quantitation of mRNA levels. Expression of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and interleukin (IL)-10 mRNA was elevated in CSF cells of MS patients. IFN-gamma and IL-10 mRNA levels were higher in MS patients than in other inflammatory neurological diseases. In many MS patients, both proinflammatory and immunoregulatory cytokine messages were detected in the CSF compartment. Such immune reactivity in CSF, as opposed to the peripheral compartment, did not correlate with the clinical activity of the disease.

Cutaneous reactions to recombinant human interferon beta-1b: the clinical and histologic spectrum

BACKGROUND

Recombinant human interferon beta-1b has been recently approved for the treatment of multiple sclerosis. A significant proportion of patients treated with this medication experienced cutaneous reactions.

OBJECTIVE

We describe the clinical and histologic features of cutaneous reactions to recombinant human interferon beta-1b.

METHODS

Consecutive patients with cutaneous reactions to recombinant interferon beta-1b were evaluated clinically and by biopsy.

RESULTS

Clinical lesions varied from subtle uninflamed sclerotic dermal plaques to erythematous plaques to cutaneous ulcers at injection sites. The nonsclerotic lesions were frequently painful. The firm plaques showed fibrosis histologically, whereas nonsclerotic inflammatory lesions demonstrated a consistent pattern of vascular thrombosis. Hematologic evaluation demonstrated platelet activation in most patients with inflammatory lesions, a feature also noted before interferon treatment in some patients.

CONCLUSION

Therapy with recombinant interferon beta-1b is associated with a spectrum of cutaneous reactions and vascular thrombosis.

Microglial production of TNF-alpha is induced by activated T lymphocytes. Involvement of VLA-4 and inhibition by interferonbeta-1b

TNF-alpha is a proinflammatory cytokine involved in many inflammatory conditions such as Crohn's disease, rheumatoid arthritis, cachexia, AIDS, and multiple sclerosis (MS). TNF-alpha is produced mainly by cells of the macrophage lineage, which includes microglia in the central nervous system. Here, we describe a mechanism through which TNF-alpha is generated by microglia. We show that activated human T lymphocytes induce the microglial production of TNF-alpha, and that is attenuated by a functional blocking antibody to CD49d, the alpha chain of the VLA-4 integrin on T cells. We also report that interferonbeta-1b (IFNbeta-1b), a drug that alleviates symptoms in MS, downregulates the expression of CD49d and reduces TNF-alpha production, mechanisms which can help account for its efficacy in MS.

Role of interferons in demyelinating disease

Interferon beta 1b (Betaseron) was licensed by the U.S. Federal Food and Drug Administration in July 1993 as the first treatment to alter the natural history of multiple sclerosis (MS). The drug, injected subcutaneously every other day, reduced the frequency of relapses and the expansion of central white matter pathology as measured by MRI. Twelve previous interferon trials in MS, employing a variety of interferon preparations, doses and routes of administration, preceded this trial and provided the scientific foundation for its success. Beta interferon therapy probably inhibits gamma interferon to achieve its therapeutic effect. Future MS therapy may require combination treatment with multiple agents with complimentary immunologic effects.

Mechanisms of immune injury in multiple sclerosis

In this review, we address current concepts regarding the mechanisms of tissue damage that lead to demyelination and oligodendrocyte loss in multiple sclerosis. Particular emphasis has been placed on examining the MS lesion for evidence for pathogenetic processes that have been implicated from various in vivo and in vitro model systems. Central in this analysis has been the evaluation of the various effector cell types and their products. The results strongly support the conclusion that proinflammatory cytokines are major mediators of tissue damage, through the activation of inflammatory cells and resident glial cells. A role for antibody is also discussed, particularly as part of an antibody-dependent cell mediated demyelinating process. Minor populations of lymphocytes may also participate by defining the nature of the immunological microenvironment.

Inflammation in EAE: role of chemokine/cytokine expression by resident and infiltrating cells

Experimental allergic encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system (CNS) which has many clinical and pathological features in common with multiple sclerosis (MS). Comparison of the histopathology of EAE and MS reveals a close similarity suggesting that these two diseases share common pathogenetic mechanisms. Immunologic processes are widely accepted to contribute to the initiation and continuation of the diseases and recent studies have indicated that microglia, astrocytes and the infiltrating immune cells have separate roles in the pathogenesis of the MS lesion. The role of cytokines as important regulatory elements in these immune processes has been well established in EAE and the presence of cytokines in cells at the edge of MS lesions has also been observed. However, the role of chemokines in the initial inflammatory process as well as in the unique demyelinating event associated with MS and EAE has only recently been examined. A few studies have detected the transient presence of selected chemokines at the earliest sign of leukocyte infiltration of CNS tissue and have suggested astrocytes as their cellular source. Based on these studies, chemokines have been postulated as a promising target for future therapy of CNS inflammation. This review summarized the events that occur during the inflammatory process in EAE and discusses the roles of cytokine and chemokine expression by the resident and infiltrating cells participating in the process.

Basic aspects of neuroimmunology as they relate to immunotherapeutic targets: present and future prospects

The neurological diseases with definite or putative immune pathogenesis include myasthenia gravis; Lambert-Eaton myasthenic syndrome; IgM monoclonal anti-myelin-associated glycoprotein-associated demyelinating polyneuropathy; Guillain-Barré syndrome; chronic inflammatory demyelinating polyneuropathy; multifocal motor neuropathy with or without GM1 antibodies; multiple sclerosis; inflammatory myopathies; stiff-man syndrome; autoimmune neuromyotonia; paraneoplastic neuronopathies and cerebellar degeneration; and neurological diseases associated with systemic autoimmune conditions, vasculitis, or viral infections. The events that lead to these autoimmune diseases are not clear but the following sequential steps are critical: (a) the breaking of tolerance, a process in which cytokines, molecular mimicry, or superantigens may play a role in rendering previously anergic T cells to recognize neural autoantigens; (b) antigen recognition by the T-cell receptor complex and processing of the antigen via the major histocompatibility complex class I or II; (c) costimulatory factors especially B7 and B7-binding proteins (CD28, CTLA-4) and intercellular adhesion molecule (ICAM)-1 and its leukocyte function-associated (LFA)-1 ligand; (d) traffic of the activated T cells across the blood-brain or blood-nerve barrier via a series of adhesion molecules that include selectins, leukocyte integrins (LFA-1, Mac-1, very late activating antigen [VLA]-4) and their counterreceptors (ICAM-1, vascular cell adhesion molecule [VCAM]) on the endothelial cells; and (e) tissue injury when the activated T cells, macrophages, or specific autoantibodies find their antigenic targets on glial cells, myelin, axon, calcium channels, or muscle. In designing specific immunotherapy, the main players involved in every step of the immune response need to be considered. Targets for specific therapy in neurological diseases include agents that (a) interfere or compete with antigen recognition or stimulation, (b) inhibit costimulatory signals or cytokines, (c) inhibit the traffic of the activated cells to tissues, and (d) intervene at the antigen recognition sites in the targeted organ. The various immunomodulating procedures and immunosuppressive drugs currently used for nonselective neuroimmunotherapy are discussed in the context of their interference with the above-described immune mediators.

Immune and non-immune actions of interferon-beta-Ib on primary human neural cells

Systemic interferon-beta-Ib (IFN-beta-Ib) reduces the frequency of clinical exacerbations and the number of magnetic resonance imaging (MRI)-defined lesions in patients with relapsing-remitting MS. The basis for this clinical effect is not understood. While IFN-beta-Ib has been demonstrated to have antiproliferative and immunomodulatory effects on the systemic immune system, its actions on neural cells could also contribute to its therapeutic efficacy. In this study, we have examined possible immune and non-immune effects of IFN-beta-Ib on CNS-derived primary human cells. With respect to immune-related effects, application of IFN-beta-Ib did not decrease basal expression of HLA-DR on astrocytes or microglia, and it reduced the IFN-gamma-enhanced HLA-DR expression on adult human astrocytes only at high concentrations (1000 IU ml-1); IFN-beta-Ib at all concentrations tested did not reduce the IFN-gamma-enhanced HLA-DR expression by fetal astrocytes or adult microglial cells. In contrast, but in correspondence with the literature, the IFN-gamma-enhanced HLA-DR expression on a glioma cell line was attenuated by IFN-beta-Ib in a dose-dependent manner. With respect to non-immune effects, the number of adult human oligodendrocytes and their state of morphological differentiation were not affected by IFN-beta-Ib. Proliferation of the mitotically active fetal human astrocytes, however, was reduced by IFN-beta-Ib treatment. Lactate dehydrogenase assays revealed that IFN-beta-Ib was not toxic to neural cells, including adult oligodendrocytes and fetal human neurons. We conclude that IFN-beta-Ib lacks efficacy in down-regulating HLA-DR expression by primary human neural cells and that regulation of MHC class II antigens is unlikely to be a mechanism for its beneficial effect in MS. Finally, the lack of toxicity of IFN-beta-Ib on human neural cells is important for a drug that will probably be used widely.