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Biomedical subjects

K V Toyka

Publications and source records attributed to K V Toyka.

At least 19 recordsLinked to original sources
PubMed2000

Genetic variation at position -1082 of the interleukin 10 (IL10) promotor and the outcome of multiple sclerosis.

Interleukin-10 is a potent immunomodulatory cytokine with possible implications for the pathogenesis of multiple sclerosis. Increased IL10 mRNA expression is associated with stable disease. The interleukin 10 gene is highly polymorphic and certain haplotypes result in differential interleukin-10 expression. The presence of guanine instead of adenine at position -1082 in the IL10 promotor was shown to result in a higher IL10 production. We analysed this diallelic polymorphism in patients with multiple sclerosis but did not find any association between a certain -1082 IL10 genotype and susceptibility to or severity of multiple sclerosis.

Alleles↗
PubMed2000

Potential role of LIF as a modifier gene in the pathogenesis of amyotrophic lateral sclerosis.

Leukemia inhibitory factor (lif) is a potent survival factor for motoneurons in cell culture and in vivo. The authors screened 104 patients with ALS and 338 control subjects for mutations in the LIF gene. In four ALS patients, but in no control subject, a G-to-A point mutation at position 3400 was identified, which leads to an amino acid exchange of valine to methionine at position 64 of the mature lif protein. This region of the lif protein (AB loop) interacts with the lif receptor. The authors suggest that LIF could act as a modifier gene which, in combination with other genetic predispositions, might lead to motoneuron disease.

Adult↗
PubMed2000

Immune deficiency in mouse models for inherited peripheral neuropathies leads to improved myelin maintenance.

The adhesive cell surface molecule P(0) is the most abundant glycoprotein in peripheral nerve myelin and fulfills pivotal functions during myelin formation and maintenance. Mutations in the corresponding gene cause hereditary demyelinating neuropathies. In mice heterozygously deficient in P(0) (P(0)(+/-) mice), an established animal model for a subtype of hereditary neuropathies, T-lymphocytes are present in the demyelinating nerves. To monitor the possible involvement of the immune system in myelin pathology, we cross-bred P(0)(+/-) mice with null mutants for the recombination activating gene 1 (RAG-1) or with mice deficient in the T-cell receptor alpha-subunit. We found that in P(0)(+/-) mice myelin degeneration and impairment of nerve conduction properties is less severe when the immune system is deficient. Moreover, isolated T-lymphocytes from P(0)(+/-) mice show enhanced reactivity to myelin components of the peripheral nerve, such as P(0), P(2), and myelin basic protein. We hypothesize that autoreactive immune cells can significantly foster the demyelinating phenotype of mice with a primarily genetically based peripheral neuropathy.

Animals↗
PubMed2000

Animal models for autoimmune demyelinating disorders of the nervous system.

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) that takes a relapsing-remitting or a progressive course (reviewed in Refs 1,2). Its counterpart in the peripheral nervous system (PNS) is chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) (reviewed in Ref. 3). In addition, there are acute, monophasic disorders, such as the inflammatory demyelinating polyradiculoneuropathy termed Guillain-Barré syndrome (GBS) in the PNS, and acute disseminated encephalomyelitis (ADEM) in the CNS. Both MS and GBS are heterogeneous syndromes. In MS different exogenous assaults together with genetic factors can result in a disease course that finally fulfils the diagnostic criteria. In both diseases, axonal damage can add to a primarily demyelinating lesion and cause permanent neurological deficits. No single animal model exists that mimics all the features of human demyelinating diseases; rather, the available models reflect specific facets. Here, we focus on experimental autoimmune encephalomyelitis (EAE) and neuritis (EAN) as models in rat and mouse strains, and discuss their distinct histopathology and the roles played by different autoantigens.

Animals↗
PubMed2000

Variations in cytokine mRNA expression during normal human pregnancy.

Epidemiological data provide evidence that disease activity of T cell-mediated, organ-specific autoimmune diseases is reduced during pregnancy. Although there are several experimental animal studies on the effect of pregnancy on the immune system, the situation in humans is less clear. We therefore performed a prospective analysis of cytokine mRNA expression in whole blood by a new on-line reverse transcriptase-polymerase chain reaction technique and of serum hormone levels during pregnancy in healthy women. The control group included age-matched non-pregnant healthy women. Quantitativecytokine mRNA expression revealed significantly reduced IL-18, interferon-gamma (IFN-gamma), and IL-2 mRNA levels in the first and second trimester in pregnancy compared with non-pregnant women. No difference between groups was detected for tumour necrosis factor-alpha (TNF-alpha) mRNA. IL-4 and IL-10 mRNA were detected at low levels in only 20% of pregnant women and were reduced to a statistically significant extent in the second and third trimester compared with the control group. Changes in IL-18 mRNA expression correlated inversely with serum values for human choriogonadotropin (HCG) and IL-10 serum levels correlated with increases in serum 17beta-oestradiol levels. These data indicate immunomodulatory effects of pregnancy at the cytokine level which may be related to the variations in the clinical course of organ-specific, T cell-mediated autoimmune diseases during pregnancy.

Adolescent↗
PubMed2000

Cytokine-induced modulation of cellular adhesion to human cerebral endothelial cells is mediated by soluble vascular cell adhesion molecule-1.

Tumour necrosis factor-alpha ( TNF-alpha) has been proposed as one of the key mediators of inflammatory diseases of the CNS such as multiple sclerosis. It has been shown to induce the expression of adhesion molecules which is a prerequisite for the transmigration of immune cells through the blood-brain barrier. We therefore investigated the role of TNF-alpha in the expression and release of vascular cell adhesion molecule-1 (VCAM-1) in cultures of human cerebral endothelial cells (HCEC) in comparison with peripheral blood mononuclear cells (PBMC). A time- and dose-dependent expression of VCAM-1 and release of soluble VCAM-1 was detected in HCEC but not PBMC. TNF-alpha-induced release of soluble VCAM-1 was further increased by cotreatment with interferon-beta (IFN-beta), while IFN-beta alone did not affect VCAM-1 expression or the release of soluble VCAM-1. In addition, we observed that preincubation of PBMC with soluble VCAM-1 completely blocked their adhesion to HCEC. In conclusion, the proinflammatory effect of TNF-alpha on HCEC, which involves the induction of VCAM-1 expression and cellular adhesion, is followed by the consecutive effects of soluble VCAM-1 release in blocking adhesion and downregulating further cellular infiltration. Increasing soluble VCAM-1 release during active inflammation could be another mechanism by which IFN-beta treatment exerts protective effects in multiple sclerosis patients.

Antibodies, Monoclonal↗
PubMed1999

Comparative analysis of motoneuron loss and functional deficits in PMN mice: implications for human motoneuron disease.

We have investigated the correlation between functional and morphological deficits in PMN mice, an animal model of human motoneuron disease. Electrophysiologic investigations showed first abnormalities, i.e. reduction of M-response amplitudes, already at postnatal d 13 when the disease was not yet phenotypically apparent, and when motoneuron and motor axon numbers were still normal. After d 27, a loss of more than 30% of motoneuron axons and cell bodies was detectable in the phrenic nerve and facial nucleus, respectively. At that stage, PMN mice showed severe functional and electrophysiological deficits. At later stages of the disease when still more than 50% of motor axons and at least 60% of motoneuron cell bodies were present, the distal compound muscle action potential amplitude decreased by more than 95% in small foot muscles after sciatic nerve stimulation. We conclude that functional deficits precede structural deficits in this animal model of human motoneuron disease. Our findings are in agreement with the concept of the 'sick motoneuron' in this animal model of motoneuron disease rather than the idea of progressive loss of motoneurons resulting in disease only after a significant number of motoneurons has degenerated.

Action Potentials↗
PubMed1999

Usage of Vbeta3.3 T-cell receptor by myelin basic protein-specific encephalitogenic T-cell lines in the Lewis rat.

T-cell receptor (TCR) beta-chain usage in experimental autoimmune encephalomyelitis (EAE) seems to be much more heterogeneous than previously assumed even for a single autoantigen in an inbred animal strain. Owing to the lack of suitable antibodies, this has been demonstrated only at the RNA level so far. To characterize further the TCR elements used in the Lewis rat for the recognition of the main encephalitogenic region of myelin basic protein (MBP), BALB/c mice were immunized with T-cell hybridomas expressing non-Vbeta8.2 TCR specific for guinea pig MBP peptide aa 68-88. Two B-cell hybridomas (clones C-A11 and F-D6) producing TCR Vbeta3.3-specific monoclonal antibodies were selected. Specificity was demonstrated by RT-PCR and cloning of PCR products obtained from sorted T-cell lines and naive T cells. MBP-specific Vbeta3.3 T cells used the L-S motif in the VDJ region, were associated with Valpha2 or Valpha8 chains, and specifically recognized MBP peptide aa 68-88. Vbeta3.3 TCR-positive T cells were detected in all of a panel of six MBP-specific T-cell lines, although to a lesser degree than Vbeta8.2 TCR-positive T cells. After intravenous injection of sorted Vbeta3.3 T cells, animals developed EAE, and Vbeta3.3-positive cells were found by immunocytochemical analyses in the spinal cord. Furthermore, treatment of EAE induced by immunization with MBP was more effective when a combination of anti-Vbeta3.3 and anti-Vbeta8.2 mAbs was used. These results confirm the functional role of TCR Vbeta3.3 and thus underscore the heterogeneity of TCR usage in MBP-associated autoimmunity.

Animals↗
PubMed1999

Neonatal Guillain-Barré syndrome: blocking antibodies transmitted from mother to child.

OBJECTIVE: To investigate the role of blocking antibodies in neonatal Guillain-Barré syndrome (GBS) occurring 12 days postpartum in a child born to a mother with ongoing GBS. METHODS: We studied plasma filtrate, purified IgG, and monovalent Fab fragments from the affected mother and serum from the neonate as well as serum samples after recovery from disease 3 months later. Experiments were performed on the hemidiaphragms of adult mice and neonatal and juvenile rats. Quantal endplate currents were recorded with the perfused macro-patch clamp electrode. RESULTS: A dual effect was seen. Serum from mother and infant depressed quantal content by approximately 90% and reduced the amplitude of postsynaptic currents by 30 to 40%. The antibody nature of the blockade could be confirmed by showing that monovalent Fab fragments were similarly effective as purified immunoglobulin (Ig) G. No IgG antibodies to gangliosides, fetal or adult nicotinic acetylcholine receptor, or voltage-gated calcium channels could be detected, but IgM antibodies to the ganglioside GM1 were present. After recovery from GBS no blocking activity was seen in the sera of mother and infant. To elucidate why neonatal disease onset was delayed we examined the possible influence of early developmental changes in functional properties of the neuromuscular junction and applied the mother's active serum to postnatal rats. Although blockade was present in 23-day-old rats, it was absent in 5-day-old rats. CONCLUSION: Transplacentally transferred blocking antibodies may be specifically directed at epitopes of the mature but not the fetal neuromuscular junction.

Adult↗
PubMed1999

Nerve conduction abnormalities and neuromyotonia in genetically engineered mouse models of human hereditary neuropathies.

We performed electrophysiological studies in myelin protein mutant mice in order to characterize nerve conduction changes. We performed neurographic studies on the facial and sciatic nerves and needle electromyography (EMG). Mice homozygously deficient for the peripheral myelin protein 22 gene (Pmp22-/-) exhibited increased motor latencies, reduced nerve conduction velocities, and polyphasia of the M-response, which are the typical electrophysiological signs of dysmyelination. PMP22 +/- mice developed only mild conduction slowing at an old age and a mild reduction of the M-amplitude, which indicates mild axonal dysfunction. Mice overexpressing Pmp22 developed severe electrophysiological signs of dysmyelination. In myelin protein zero-deficient mice (P0 -/-), we found alterations similar to those found in Pmp22 -/- mice, whereas P0 +/- mice developed mildly increased sciatic nerve F-wave latencies only late in life, which indicates only mild dysmyelination. Connexin 32-deficient mice showed electrophysiological evidence of mild axonal damage. By EMG, we found the clinical and electrophysiological signs of neuromyotonia, that is, continuous spontaneous motor unit discharges, often in rhythmic patterns (myokymia), in P0 -/-, Pmp22 -/-, Trembler, Trembler-J, and Pmp22-overexpressing mice. This indicates abnormal impulse generation in these dysmyelinated nerves. In summary, our studies demonstrate nerve conduction changes in mice with myelin protein gene defects that are similar to those found in patients with Charcot-Marie-Tooth disorders. In addition, we identified new mouse models of hereditary neuromyotonia.

Animals↗
PubMed1999

Neutralizing antibodies to interleukin 1-receptor reduce pain associated behavior in mice with experimental neuropathy.

We investigated whether interleukin-1 (IL-1), a mediator of inflammatory pain, also plays a role in pain induced by nerve injury. Female C57BL/6-mice with a chronic constrictive injury of one sciatic nerve, an established model of neurogenic hyperalgesia and allodynia, were treated with different doses (10-80 microg) of a neutralizing monoclonal rat antibody to IL-1 receptor I (anti-IL-1RI). This antibody dose-dependently reduced thermal hyperalgesia and mechanical allodynia in the animals. Furthermore, immunoreactivity for the proinflammatory cytokine tumor necrosis factor-alpha (TNF) was reduced in mice treated with the highest dose of anti-IL-1RI. Degeneration of myelinated fibers was not altered by any of the treatment schedules. We conclude that IL-1 may be a mediator of hyperalgesia after nerve lesion.

Animals↗
PubMed1999

Linkage of proximal myotonic myopathy to chromosome 3q.

We performed genetic linkage analysis in nine German proximal myotonic myopathy (PROMM) families using DNA-markers D3S1541 and D3S1589 from the region of the recently discovered gene locus of myotonic dystrophy type 2 (DM2) on chromosome 3q. Two-point analysis supplied an lod score of 5.9. We conclude that a gene causing PROMM is located on chromosome 3q. PROMM and DM2 may be allelic disorders or may be caused by closely linked genes.

Chromosome Mapping↗
PubMed1999

T-cell apoptosis in inflammatory neuromuscular disorders associated with human immunodeficiency virus infection.

BACKGROUND: Apoptosis is one of the major mechanisms of CD4+ T-cell depletion in human immunodeficiency virus (HIV) infection. T cells in human inflammatory myopathies in HIV-negative individuals rarely undergo apoptosis. Currently, there is no information available concerning the fate of T cells in HIV-associated myositis and polyneuropathies. OBJECTIVE: To investigate whether apoptosis occurs in inflammatory lesions of muscle and nerve biopsy specimens of untreated HIV-positive patients with neuromuscular disorders. METHODS: T-cell apoptosis was investigated in muscle and nerve specimens from 12 patients with HIV-associated polymyositis and 8 patients with HIV-associated inflammatory polyneuropathy. These were compared with specimens from 36 HIV-negative patients with other inflammatory myopathies and from 18 patients with inflammatory polyneuropathies. Apoptosis was assessed according to morphological criteria and with the use of in situ labeling methods. RESULTS: In none of the HIV-associated disorders did we observe a substantial proportion of apoptotic T cells as assessed by nuclear morphological findings and in situ labeling techniques. Fas expression was up-regulated only in a few inflammatory cells. Positive labeling for Fas ligand was not associated with increased apoptosis of surrounding T cells. Nuclei of degenerating muscle fibers and macrophages did not show morphological signs of apoptosis and were not labeled by the tailing reaction. CONCLUSIONS: Similar to their idiopathic counterparts, in HIV-related polymyositis and inflammatory neuropathy, T-cell inflammation is not cleared by apoptosis. The observations are consistent with the non-self-limited nature of endomysial or endoneural inflammation and suggest that in HIV-positive patients, the T-cell elimination is differentially regulated in the lymphoid organs as compared with neuromuscular tissues.

Apoptosis↗
PubMed1999

Mechanisms of high-dose intravenous immunoglobulins in demyelinating diseases.

Administration of high-dose intravenous immunoglobulins has become one of the most successful new treatment regimens for demyelinating diseases. In a decade of molecular medicine, it came as a surprise that a natural blood product would prove effective in several disorders, including Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy, and, probably, multiple sclerosis. Many experimental studies, both in vivo and in vitro, have shown that intravenous immunoglobulins can interfere with the immune system at several levels. In addition, intravenous immunoglobulins may promote remyelination in demyelinating disease associated with viral infections. At present, no single mode of action has been identified as the crucial mechanism, which leads us to suggest that multiple effects may act in concert.

Antibodies, Anti-Idiotypic↗
PubMed1999

Comparison of maximal voluntary isometric contraction and Drachman's hand-held dynamometry in evaluating patients with amyotrophic lateral sclerosis.

Maximal voluntary isometric contraction (MVIC) is a standard tool for assessment of muscle strength in treatment trials for amyotrophic lateral sclerosis (ALS). There is need for more practical bedside techniques especially for severely disabled patients. Hand-held dynamometry (HH-Dyn) is an inexpensive and easy-to-handle device. MVIC was measured in five proximal muscle groups bilaterally and compared with HH-Dyn in 43 ALS patients. After a training period we found good intrarater correlation for HH-Dyn (r = 0.99), with a low coefficient of variation. Measurements tended to become more accurate after repeated testing due to practice effects in examiners and patients. Overall correlation between HH-Dyn and MVIC was good [r = 0.85 (P < 0.01)]. Strength-range-specific analysis showed a significant linear correlation up to 20 kg (44 lbs.) [r = 0.57 (P < 0.01)]. However, we found a tendency to underestimate muscle strength above 10 kg by HH-Dyn as compared with MVIC, but this became meaningful only above a force of 20 kg. HH-Dyn provides a strength estimate with a precision close to MVIC in weak muscle groups (MRC grade 4). With standardization and appropriate training, HH-Dyn is a useful bedside test, providing an alternative to MVIC for follow-up assessment in ALS.

Adult↗