Multiple sclerosis: immunological findings and possible implications for therapy

IgA antibodies against gliadin and gluten in multiple sclerosis

BACKGROUND

Multiple changes in antibodies against various antigens are found in multiple sclerosis (MS).

OBJECTIVE

We wanted to measure immunoglobulin A (IgA) antibodies to some common food antigens in MS and also IgG against gliadin and gluten.

METHODS

The IgA antibodies were measured in serum against gluten, gliadin, lactoglobulin, lactalbumin, casein and ovalbumin in patients with MS and controls using ELISA technique. IgG was likewise measured for gluten and gliadin.

RESULTS

Highly significant increases compared with controls were found for IgA and IgG antibodies against gliadin and gluten. IgA antibodies against casein were significantly increased. Anti-endomycium and anti-transglutaminase antibodies were negative.

CONCLUSIONS

The data presented indicate that there may be a possible moderately increased uptake of some specific proteins from the gut in MS compared with controls.

Early synthesis and correlation of serum anti-thyroid antibodies with clinical parameters in multiple sclerosis

A high frequency of anti-thyroid antibodies has been demonstrated in multiple sclerosis (MS), but there is a lack of data on the possible association of thyroid autoimmunity with disease activity. To assess whether anti-thyroid antibodies are synthesized early in MS or are induced over the course of the disease and whether or not they are correlated with clinical findings, we assayed serum anti-peroxidase and anti-thyroglobulin antibodies in 129 relapsing-remitting MS patients at the time of diagnosis and prior to any immunosuppressive or immunomodulatory treatment. Anti-peroxidase antibodies were detected in 28/129 (21.7%) MS patients, compared to 12/130 (9.2%) neurological controls (P=0.006) and 8/152 (5.3%) normal healthy subjects (P<0.0001). High titres of anti-thyroglobulin antibodies were detected in 11/129 (8.5%) MS patients compared to 6/130 (4.6%) patients with other neurological diseases (P=0.22) and 5/152 (3.3%) normal healthy subjects (P=0.07). Anti-peroxidase antibodies were associated with initial relapse in 14 of 28 (50%) of the patients compared to 18/101 (18%) without antibodies (P=0.001). Similarly, anti-thyroglobulin antibodies were associated with first relapse in 8/11 (73%) of the patients compared to 11/118 (9.3%) of those without (P<0.0001). However, there was no correlation between anti-thyroid antibody titres and disease duration or CSF IgG index values. By contrast, a significant inverse correlation was found between anti-thyroglobulin antibody titres and EDSS score (r(s)=-0. 75; P=0.008). Our findings demonstrate that anti-peroxidase and anti-thyroglobulin antibodies are synthesized early in relapsing-remitting MS and are associated with early clinical disease activity. Furthermore, high titres of anti-thyroglobulin antibodies are associated with low disability scores, suggesting a possible protective role of these antibodies that deserves further investigation.

Analysis of lymphocyte subpopulations in cerebrospinal fluid and peripheral blood in patients with multiple sclerosis and inflammatory diseases of the nervous system

We analysed different subsets of lymphocytes from peripheral blood (PB) and cerebrospinal fluid (CSF) by flow cytometry in order to determinate alterations in patients with multiple sclerosis (MS) in acute relapse and viral inflammatory neurological disease (IND). We found increased levels of adhesion molecules (LFA-1 and beta1 integrin) in the CSF of patients with MS and IND compared to NIND. CD4+/CD8+ ratio was significantly higher in CSF of MS as compared with all groups analysed and compared with PB. We detected a significantly higher expression of the interleukin-2 receptor in PB of MS patients when compared with other groups. In patients with IND a significant higher expression of the interleukin-2 receptor was found in the CSF compared with MS and NIND. Our findings indicate that the activation of T lymphocytes primarily occurs in the peripheral immune compartment in MS and the increase of adhesion molecules in CSF is related to inflammatory disorders and not only to MS.

Interferon-beta-1-b (IFN-B) decreases induced nitric oxide (NO) production by a human astrocytoma cell line

Inducible nitric oxide synthase (iNOS) is expressed by astrocytes in demyelinating regions of multiple sclerosis (MS) brain plaques, suggesting that NO contributes to MS pathology. Since the immunosuppressive cytokine IFN-B ameliorates MS disease activity, it is of interest to assess the modulatory role of IFN-B on NO production. We studied the effects of IFN-B, as well as dexamethasone, IL-10, and transforming growth factor-beta (TGF-B), on cytokine-induced NO production by the human astrocytoma cell line, A172. L-NMMA and aminoguanidine, competitive inhibitors of iNOS suppressed NO production as measured by the NO byproduct, nitrite, as did IFN-B. Dexamethasone enhanced NO production, and IFN-B decreased the amount of the enhancement. Neither IL-10 nor TGF-B inhibited nitrite production. The therapeutic effect of IFN-B in MS may be partly due to suppression of pathogenic NO production.

Insights into the aetiology and pathogenesis of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system, and the most common neurological disease affecting young adults. Multiple sclerosis is a clinically heterogeneous disorder. It is believed to be an autoimmune disease, with cell-mediated and humoral responses directed against myelin proteins. This hypothesis largely comes from pathological parallels with an animal model, experimental autoimmune encephalomyelitis (EAE). Autoimmunity to myelin proteins in humans may be inadvertently triggered by microbes which have structural homologies with myelin antigens (molecular mimicry). As with other autoimmune diseases, susceptibility to MS is associated with certain MHC genes/haplotypes. Full genomic screening of mutiplex families has underscored the role for MHC genes as exerting moderate but the most significant effects in susceptibility. The primary target autoantigen in MS has yet to be definitively identified, but as well as the major myelin proteins, it is now clear that minor myelin components, such as myelin oligodendrocyte glycoprotein (MOG) may play a primary role in disease initiation. This review examines the current knowledge about the aetiology and pathogenesis of MS, and the important similarities with EAE. A better understanding of the molecular mechanisms of autoimmune pathology will provide the basis for more rational immunotherapies to treat MS.

Frequency and significance of antinuclear antibodies in multiple sclerosis

In a prospective sample of patients with multiple sclerosis (MS) we found a high frequency of antinuclear antibodies (ANA), 22.5%, confirming results from previous studies. ANA occurrence did not correlate with gender, age, duration of MS, MS course, or disability in either the prospective and retrospective samples of MS patients. In 16 patients with MS tested at two time points, ANA occurrence did correlate with MS disease activity. This suggests that the high frequency of ANA in MS reflects ongoing immune dysregulation.

Correlation between interferon production and clinical disease activity in patients with multiple sclerosis

We determined the interferon (IFN) serum levels and in vitro activated IFN production in eight patients with relapsing/ remitting multiple sclerosis (MS), using a whole-blood test system and the mitogen concanavalin A and the viral antigen Newcastle disease virus for induction of the IFN production. During the overall study period of 12 months we observed, in relation to clinical disease progression, a biphasic increase in the individual IFN alpha and IFN gamma production. While mitogen-induced IFN gamma synthesis showed a significant augmentation prior to the onset of a new relapse (P < 0.05), virus-induced IFN alpha production showed a temporal delayed increase which was related to clinical remission (P < 0.01). The observed fluctuations in the individual production of both IFN subtypes were not reflected in the sera of the patients. Although the reason for the temporal different imbalance in the production of both IFN subtypes remains unknown, the observed association between increased IFN alpha production and clinical remission emphasizes a possible role for type 1 IFNs in the resolution of the MS relapse.

Immunologically induced electrophysiological dysfunction: implications for inflammatory diseases of the CNS and PNS

During inflammation of the central or peripheral nervous system, a high number of immunologically active molecules, including bacterial or viral products as well as host-derived cytokines, are released. Patients suffering from inflammatory CNS or PNS diseases often develop transient symptoms with a rapid recovery, which obviously cannot be accounted for by immunologically induced tissue damage. These observations led to the hypothesis that immunologically active molecules can affect directly the electrophysiological functions of neurons and glial cells. Evidence for this hypothesis came from in vitro studies showing that cytokines, such as interleukins or tumor necrosis factors, arachidonic acid and its metabolites, interfere with electrophysiological properties of neurons or glial cells. These molecules affect ion currents, intracellular Ca2+ homeostasis, membrane potentials, and suppress or enhance the induction and maintenance of long-term potentiation. Similarly, virus proteins from human immunodeficiency virus type I were found to alter intracellular Ca2+ concentrations of neurons and astrocytes by modulating either transmitter receptors and channels or membrane transporters. Cerebrospinal fluid from MS patients contains factors which increase Na+ current inactivation and thereby reduce neuronal excitability. Immunoglobulins in sera of patients suffering from multifocal motor neuropathy and from acquired neuromyotonia interfere with nerve fibers, inducing alterations of conduction. Increased knowledge of these mechanisms will help to explain the pathogenesis of neurological symptoms and may provide a rationale for new therapeutic strategies.

Emerging treatments in multiple sclerosis: azathioprine and mofetil

Global immunosuppression instead of focused selective or specific immunomodulating strategies may still be relevant in diseases with chronic and broad immune dysregulation such as multiple sclerosis (MS). Among classical or new immunosuppressive drugs, two of them, both inhibiting purine synthesis, show an attractive profile for MS treatment. Azathioprine (AZA) is the most anciently and widely used global immunosuppressive drug in MS. Despite founded initial fears, it can be stated today that AZA is usually well tolerated and compatible with normal daily activities, that it requires minimal monitoring and does not significantly increase the risk of cancer induction after 5 years of continuous usage at the conventional 2.5 mg/kg daily dose. The only two presently available well conducted trials of AZA in ambulatory patients with relapsing-remitting MS show marginally significant beneficial results of AZA treatment on relapse frequency and disability. Some preliminary data on brain MRI are also promising. Mycophenolate mofetil (MMF) affects mainly the desired cell types, with a good safety profile, a rapidly reversible activity, and an absence of mutagenic effect and chromosome breakage. However, it remains to be shown that promising experimental results can be converted into significant clinical results in MS. It is presently demonstrated for AZA and it is presumable for MMF that neither drug is able to cure MS. However, it can be anticipated that either drug in combination with other strategies such as recombinant beta interferon could represent a significant adjunct for the therapeutic control of MS, at least in early ambulatory relapsing-remitting MS. Presently, the choice between the old, no longer 'sexy', but well-known drug as AZA and a young, appealing, but still to be better evaluated drug (notably for the long run) as MMF is a matter of personal, community, industrial and scientific inclination.

The immune profile of multiple sclerosis: T-lymphocyte effects predominate over all other factors in cyclophosphamide-treated patients

It is widely believed that multiple sclerosis is a T-cell mediated autoimmune disease associated with abnormalities in immunoregulation. This large, prospective study evaluated the lymphocyte immunophenotypic profile of 246 MS patients, divided clinically into a remitting/relapsing group (n = 176) and a progressive group (n = 70), and compared their results to those of 117 healthy controls. All patients were found to have significantly elevated percentage and absolute numbers of IL2R+CD3+ cells as well as depressed percentages of CD45RA+CD4+ cells. However, when the factor of treatment with cyclophosphamide (CY) versus no treatment or treatment with other agents was used to group patients, dramatic declines in both percentages and absolute numbers of CD45RA+CD4+ cells were discovered. These declines were associated specifically with CY and and could be explained by this factor independent of the clinical state of the patient. The effects were seen in patients undergoing current treatment or in those exposed to CY in the near or remote past. These findings highlight the confounding effect of specific treatments on the immune profile of MS patients groups and suggest that there may be important implications for cellular function and clinical outcome in these and other patient groups.

Functional defects in peripheral blood T cells of multiple sclerosis patients. Diminished in vitro responsiveness in accessory cell dependent activation systems

Function and phenotype of peripheral blood (PB) T cells in multiple sclerosis (MS) patients were analyzed. In whole blood cultures, T cell proliferation of multiple sclerosis (MS) patients, using soluble CD3 mAb and CD2 mAb as stimulants, was reduced in comparison to healthy controls. A similar difference was seen when isolated PBMC were tested after stimulation with soluble CD3 mAb. However, in accessory cell-independent activation systems, i.e. after stimulation of PBMC with immobilized CD3 mAb or after co-stimulation with CD28 mAb, both patients and controls responded equally well. Phenotypical analysis of the circulating T cell population showed that there were no differences in the percentage of CD26+, 'memory' (CD45R0+) or 'effector' (CD4+CD45R0+CD27-) cells between MS patients and healthy controls. Finally, although MS patients did show an enhanced proportion of 'naive' (CD4+CD45RA+) T cells, this did not correlate with the observed functional defects.

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.

Cytokine induction of heat shock protein expression in human oligodendrocytes: an interleukin-1-mediated mechanism

In this study, we examined the role of cytokines, known to be in elevated levels in multiple sclerosis (MS) plaques, in regulating oligodendrocyte (ODC) expression of heat shock protein (hsp) in human brain-derived glial cell cultures. Using dual-stain immunohistochemistry, we initially compared the ability of a mixture of cytokines (IL-1 alpha, IL-1 beta, IL-2, IL-6, IL-8, TNF-alpha, TNF-beta, IFN-beta and IFN-gamma) with that of physical stimuli such as heat shock and peroxide, to increase cellular expression of the mainly inducible hsp72 species in mixed glial cell cultures (containing ODC, astrocytes and microglia). Similar to heat shock and peroxide, the cytokine mixture induced hsp72 expression only in ODC (70 +/- 5% vs. a baseline of 3 +/- 1% positive cells). When used individually, however, only IL-1 alpha (79 +/- 3%), IFN-gamma (70 +/- 2%) and TNF-alpha (65 +/- 5%) induced ODC hsp72 expression in mixed glial cell cultures. In purified ODC preparations, only IL-1 alpha induced hsp72 expression (84 +/- 4%). An IL-1 receptor antagonist (IL-1ra), abrogated hsp72 induction by IL-1 alpha (16 +/- 3%) as well as that due to IFN-gamma (14 +/- 1%) and TNF-alpha (13 +/- 2%) in mixed glial cell cultures. Furthermore, ODC express IL-1 receptors, detected by confocal laser scanning microscopy. Our data indicate that cytokines mediate hsp induction in ODC possibly via a final common pathway involving IL-1 binding to its receptor on ODC. Such interaction could enhance any putative ODC-immune interactions which are dependent on hsp molecule recognition.

Influence of FK 506 (tacrolimus) on circulating CD4+ T cells expressing CD25 and CD45RA antigens in 19 patients with chronic progressive multiple sclerosis participating in an open label drug safety trial

We have taken the opportunity of a clinical trial of the potential efficacy and safety of FK 506 (tacrolimus) in chronic progressive multiple sclerosis (MS) to examine the influence of this potent new immunosuppressant on circulating T-lymphocytes in an otherwise healthy non-transplant population. Peripheral blood levels of subsets of CD4+ T lymphocytes expressing the activation molecule interleukin-2 receptor (p55 alpha chain; CD25) or the CD45RA isoform were determined sequentially in 19 patients that were treated continuously with oral FK 506 (starting dose 0.15 mg/kg/day) for 12 months. No significant change in the proportion of circulating CD25+ CD4+ cells was observed over the study period in which the mean trough plasma FK 506 level rose from 0.3 +/- 0.2 to 0.5 +/- 0.4 ng/ml. There was also no significant effect of FK 506 on the percentage of CD45R+ CD4+ cells in the peripheral blood at 12 months compared with pretreatment values. Analysis of a subgroup of 7 patients, who showed a sustained reduction in CD25+ CD4+ cells and a reciprocal increase in CD45RA+ CD4+ cells for at least 6 months after start of treatment, did not reveal any difference in disability at one year compared with the treatment group as a whole. The side effects of FK 506 were mild and the overall degree of disability estimated by the mean Kurtzke expanded disability status scale (EDSS) score or the ambulation index did not deteriorate significantly in the 19 patients studied over the 12 months of FK 506 administration.

Lymphocytes and macrophages outnumber oligodendroglia in normal fish spinal cord

As shown by staining with a monoclonal antibody against fish CD45, leukocytes are present in very large numbers in the fish central nervous system. Their subtypes were distinguished by electron microscopy and found to include all major hematogenous forms except thrombocytes, the most numerous being tissue macrophages and lymphocytes. As a population, they differ fundamentally from ramified microglia, the restricted form of myeloid cells present in the central nervous system in mammals. They are rare in most grey matter regions but are concentrated in myelinated fiber tracts as well as in certain strata of the radial glial network. The macrophages engulf discarded myelin and outnumber the oligodendrocytes in normal spinal cord white matter, where the density of lymphocytes is > 5000-fold greater than reported in rat.