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S100B protein, glia and Gilles de la Tourette syndrome
doi: 10.1053/ejpn.2001.0399 available online at http://www.idealibrary.com on European Journal of Paediatric Neurology 2001; 5: 15±19
ORIGINAL ARTICLE
S100B protein, glia and Gilles de la Tourette syndrome RALPH VAN PASSEL,1 WIM AJM SCHLOOZ,2 KAREL JB LAMERS,3 WIM AJG LEMMENS,4 JAN J ROTTEVEEL1 Departments of 1Paediatric Neurology IKNC, 2Child Psychiatry ACKJON, 3Neurology, 4Statistics, University Hospital Nijmegen, The Netherlands
Activated glial cells play an important role in a variety of neurological disorders. This study examines S100B protein levels in the serum of patients with Gilles de la Tourette syndrome, as potential marker for glial cell function. Two groups of children were examined: 61 reference patients and 33 patients with Gilles de la Tourette syndrome. It was found that S100B serum concentrations in the reference group decrease with increasing age. Furthermore it was found that the mean S100B concentration in serum of children with Gilles de la Tourette syndrome is significantly higher than in the reference group. These preliminary results suggest that glial tissue might be involved in the pathophysiology of the syndrome. Keywords: Gilles de la Tourette syndrome. S100B protein. Glial tissue.
Introduction Gilles de la Tourette syndrome (GTS) is characterized by childhood onset of multiple motor and vocal tics and related somatosensory urges, waxing and waning over time.1,2 Recent reviews summarize pathogenic factors, which have been investigated in GTS.3,4 The effect of e.g. haloperidol suggests involvement of dopaminergic pathways, as does the increased cerebrospinal fluid levels of monoamine transmitter metabolites. Neuroimaging studies suggest that the basal ganglia±thalamocortical pathways may be involved. Magnetic resonance imaging (MRI) studies demonstrate reduced volume and abnormal asymmetries of the caudate, putamen and globus pallidus. In vivo positron emission tomography (PET) research suggests that the reduction in basal ganglia volume is accompanied by decreased basal ganglia metabolism and lower blood flow, as well as reduced glucose rates for the frontal and
cingulate/limbic cortical areas. Recent single photon emission computed tomography (SPECT) investigations have reported increased dopaminetransporter levels in the basal ganglia of GTS patients.3,4 GTS-like symptoms can occur after streptococcal infection or Lyme disease, possibly by the process of molecular mimicry, as seen in paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS).5 Glial tissue has not yet been studied as potential pathogenic factor in GTS. Historically, glia were thought to be merely support cells. There are far more glia±neuron connections than neuron±neuron connections. Astroglial cells are the predominant cell types (85%); microglia (10%) and oligodendrocytes (5%) are the remainder. Glial cells communicate mainly locally or paracrine. Glial cells appear to tightly regulate each other's morphology, activity and secretion of products, through the production of a variety of factors, including cytokines and growth factors.6
Received 15.2.2000. Revised 11.10.2000. Accepted 7.11.2000. Correspondence: Jan J Rotteveel PhD, MD, Department of Paediatric Neurology, University Hospital Nijmegen, PO Box 9101, 6500HB Nijmegen, The Netherlands. e-mail: J.Rotteveel#cksiknc.azn.nl
1090±3798/01/05/0015+5 $35.00
& 2001 European Paediatric Neurology Society
16 A member of a family of calcium-binding proteins, S100 is one of many brain-specific proteins. It binds calcium in cytosol. It is involved in the cell cycle and in interactions in the cytoskeleton and indirectly influences the energy metabolism of the cell. In 1965 Moore isolated a fraction from bovine brains which he believed contained nerve-specific proteins. He called it S100 because it dissolved in 100%-saturated ammonium sulphate.7 The term `S100' refers to a mixture of dimeric proteins consisting of two subunits a and b. Three isoforms are known: S100B (bb) is a multifunctional protein and is present in high concentration in glial cells and Schwann cells of the central and peripheral nervous system; S100A (ab) is present in glial cells but not in Schwann cells; and S100AO (aa) is found exclusively in neurons. S100 can also be found in low concentrations in non-nervous tissues and cells such as adipose tissue, melanocytes and T-lymphocytes.7 S100B is a cerebral marker protein for glial integrity.8 It has been ascertained that the appearance of this protein in blood is a reliable indicator of active glia cell damage in the nervous system in a variety of pathological conditions.9,10 The S100-gene has been located on chromosome 21 (21q22.2-22.3). Triplication of the chromosome in Down syndrome could result in an altered geneexpression of S100B resulting in the neurological conditions associated with the syndrome.11 Overexpressed S100B, as seen in Down syndrome and Alzheimer's disease, was associated with cognitive dysfunction.12 The plasma S100B concentration in healthy adults is age- and sex-independent13 We do not know of any published reference data on plasma S100B protein concentrations in children.
Material and methods Subjects To establish reference values, 35 boys and 26 girls without acute neurological disorders were selected randomly, after parental consent, from the paediatric outpatient clinics. Their age range was 0.2±20.0 years, mean 6.4+5.2 years. Children with acute neurological problems were excluded because of possible effects on the S100B concentration. The patients were divided into two subgroups (IA and IB). Group IA comprised 33 patients without neurological abnormalities: 20 boys and 13 girls, age range 0.2±19.7 years, mean 8.3+4.9 years. Group IB comprised 28 patients with chronic non-progressive neurological abnormalities: 15
Original article: R Van Passel et al. boys and 13 girls, age range 0.5±20.0 years; mean 4.3+4.7 years. Group IB consisted of patients with learning disorders and behavioural problems. Another group (II) consisted of 33 children with GTS: 32 boys and 1 girl, age range 6.2±14.5 years, mean 10.9+2.5 years. The mean age at the time of diagnosis was 10.1 years, range 5.9±14.5 years. The group was restricted to cases of GTS as defined by a multidisciplinary team consisting of a paediatric neurologist, a child psychiatrist and a neuropsychologist. All patients were referred for paediatric movement disorders to the outpatients clinic at the University Hospital. The diagnostic criteria of DSM±IV14 were used. Patients with co-morbid pathology, which might influence the level of S100B, were excluded, e.g. active epilepsy, subacute encephalopathy.
Laboratory investigations Blood samples were taken with informed consent. Protein S100B was assayed using a commercially available monoclonal two-sided immunoluminometric assay kit (Sangtec1 100, Sangtec Medical/ Bromma, Sweden).15,16 The assay kit measures only the b-subunit of the protein S100 as defined by three monoclonal antibodies. Antibody-coated polystyrene tubes serve as solid phase in which the coated monoclonal antibody reacts with the S100B protein in the sample. During a second incubation the tracer antibody binds to the immobilized S100B. The antiS100B tracer conjugate contains a covalently bound isoluminol derivative. For detection the isoluminol is oxidized by alkaline followed by light emission. The whole procedure is performed in an automated LIA-mat system 300 with a detection threshold below 0.02 mg/litre. The recovery rates were between 94±113%. The precision was calculated for concentration ranges in serum from 0.28 to 4.17 mg/litre. The interassay concentration values range from 10.3 to 2.7%. The monoclonal antibodies detect the monomeric S100B and the dimeric isoforms: S100 A1-B and S100 B-B. Monomeric S100 A1 and dimeric isoforms S100 A1-A1 are not detected. It is not exactly known which S100 subtypes (monomeric or dimeric forms) are released in blood in controls and in clinical entities like stroke or malignant melanomas.16 S100B concentrations were determined in serum of the patient.
Statistics The data were entered into a statistical model. After logarithmic transformations, the general
Original article: S100B protein and Gilles de la Tourette syndrome
17
linear model was used to search for age- and/or sex-dependence in the reference group. In further analyses the Student's t-test and Pearson correlation test were used. Regression analysis was performed to yield age-related reference intervals. The median value and reference limits, as the 5th and 95th percentiles, were calculated; p-values for age-dependency were calculated.
Results Reference group The reference group could be divided in two subgroups. Groups IA (without neurological abnormalities) and IB (with chronic non-progressive neurological abnormalities) differed slightly in age, 4.3+4.7 and 8.3+4.9 respectively. The groups IA and IB did not differ on S100B serum concentrations after correction for age. We found no sex dependency. These patients were used as the reference group in the subsequent analyses.
Age dependence In the reference group S100B concentrations in serum show age dependency. In children the concentration of S100B in serum decreases with increasing age (r 70.53) (Fig. 1). Ln (S100B) 71.44±0.071 * age. Residual error: 0.596. Se (intercept) 0.12. Se (slope) 0.015. The p5, p50 and p95 of the S100B concentrations in serum for different ages were calculated (Table 1).
Gilles de la Tourette syndrome In the children with GTS the mean S100B serum concentration is significantly higher than in the reference group (p 0.009) (Fig. 2).
Discussion This study identified a significant increase of the mean S100B serum concentration in children with GTS. The raised S100B serum concentrations might suggest glial tissue involvement. Almost all research on GTS has been focused on neuronal tissue. S100B is a multifunctional protein.8 Disturbance of S100B serum concentrations might lead to a variety of neurological dysfunctions.
Fig. 1. S100B serum concentrations of the reference group against age. Reference area S100B against age with p5, p95 and median p50. Concentration in mg/litre. Closed circles: with chronic non-progressive neurological abnormalities. Open circles: without neurological abnormalities.
S100B is secreted by proliferating astrocytes, particularly during neurite outgrowth from cortical cells.17 S100B is seen early in the development of the fetal brain and seems to be an important neurotrophic agent, affecting neuroblasts and glia.12 S100B also has autocrine effects as a stimulant of astrocyte proliferation. It can promote, in tissue culture studies, the extension of serotonergic neurites18 and it plays a role in lesioninduced collateral sprouting and reactive synaptogenesis.19 S100B may be involved in the coordinated development and maintenance of the central nervous system by synchronously stimulating the differentiation of neurons and the proliferation of astroglia.20 A slight increase in concentration of S100B might reflect a disturbance in the development and maintenance of the integrity of the central nervous system. Astroglial cells are an active part of the blood±brain barrier. Astrocytes and derived factors maintain the morphologic, phenotypic and physiological properties of the blood±brain barrier. Astroglial cells may also modulate endothelial cell properties Table 1 S100B (mg/litre) in the reference group for different ages. Age (years) 0 3 6 9 12 15 18
p5
p50
p95
0.089 0.072 0.058 0.047 0.038 0.031 0.025
0.237 0.191 0.154 0.125 0.101 0.081 0.066
0.630 0.510 0.412 0.333 0.269 0.217 0.175
18
Original article: R Van Passel et al.
Acknowledgements We thank Dr W Gerrits for collecting the laboratory samples, ACAM van der Pijll for her neuropsychological analyses, HPM de Reus and WJA van Geel for their laboratory support, and Dr AW Sloman for his linguistic corrections.
References Fig. 2. S100B serum concentrations of the GTS group against age. With p5, p95 and median p50 of the reference group. Concentration in mg/litre.
associated with the entry of inflammatory cells into the brain.21 This is interesting, because GTS-like symptoms can occur after streptococcal infection or Lyme disease.5 Antineural antibodies are elevated in some patients with GTS.5 The presence of antibodies may reflect an alteration of the blood± brain barrier that allows central nervous system antigens access to immunocompetent cells.22. Dysfunctioning of glial tissue might result in alterations in the blood±brain barrier. Glia are involved in neurotransmission; they store and release neurotransmitters and nutrients. Activated glial cells play an important role in a number of neurodegenerative diseases. This activation is marked by hypertrophy and results in the expression of structural proteins, adhesion molecules, antigens and cytokines, such as S100B, all capable of contributing to neuronal damage.23 Reactive glial cells act as an opposing force to neurotrophic astroglia, competing to regulate the survival of neurons.6 Thus, dysfunction in glial tissue could alter a number of regulatory systems. The delicate interaction that exists between glial cells and neurons is crucial for the maintenance of neuronal functioning and integrity.6 Dysfunctioning of glial tissue could alter this balance. S100B serum concentrations are age-dependant in the paediatric age group. A remarkable difference is found between the S100B concentrations in serum and in liquor. In liquor the S100B concentration increases with age.9,10 In serum the S100B concentrations decreases with age. The mechanism of this effect is thus far unknown. The elevation of the mean S100B concentration in GTS is noteworthy and the observation justifies further research into the possible role of glial tissue in the pathogenesis of GTS.
1 Cohen DJ, Leckman JF. Developmental psychopathology and neurobiology of Tourette's syndrome. J Am Acad Child Adoles Psychiat 1994; 35: 245±250. 2 Robertson MM. Annotation. Gilles de la Tourette syndrome ± An update. J Child Psychol Psychiat 1994; 35: 597±611. 3 Sheppard DM, Bradshaw JL. Tourette's and comorbid syndromes: Obsessive compulsive and attention deficit hyperactivity disorder. A common aetiology? Clin Psych Rev 1999; 19: 531±552. 4 Leckman JF, Pauls DL, Peterson BS et al. Pathogenesis of Tourette's syndrome. J Child Psychol Psychiat 1997; 38: 119±142. 5 Singer HS, Guiliano JD et al. Antibodies against human putamen in children with Tourette's syndrome. Neurology 1998; 50: 1618±1624. 6 Vincent VAM, Tildes FJH, Van Dam A-M. Production, regulation and role of nitric oxide in glial cells. Med Inflammat 1998; 7: 239±255. 7 Zimmer DB, et al. The S100 protein family: History, function and expression. Brain Res Bull 1995; 37: 417± 429. 8 Michetti F, Massoro A, Russo G, Rigon O. The S100 antigen in cerebrospinal fluid as a possible index of cell injury in the nervous system. J Neurol Sci 1980; 44: 731±743. 9 Persson L, Hardemark HG, Gustafson J et al. S100 protein and neuron-specific-enolase in cerebrospinal fluid and serum: markers of cell damage in human central nervous tissue. Stroke 1987; 18: 911±918. 10 Lamers KJB, van Engelen BGM, Gabreels FJM, et al. Cerebrospinal neuron-specific enolase, S100 and myelin basic protein in neurologic disorders. Acta Neurol Scand 1995; 92: 247±251. 11 Marks A, Allore R. S100 protein and Down's syndrome. Bioassays 1990; 12: 381±383. 12 Fwu-Shan Sheu et al. Glial-derived S100b protein selectively inhibits recombinant B protein kinase c phosphorylation of neuron specific protein F1/ GAP43. Mol Brain Res 1994; 21: 62±66. 13 Wiesmann 1, Missler U, Gottmann D, Gehring S. Plasma S100B protein concentration in healthy adults is age- and sex-independent. Clin Chem 1998; 44: 1056±1058. 14 American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (DSM±IV), American Psychiatric Association: Washington DC, 1994.
Original article: S100B protein and Gilles de la Tourette syndrome 15 Wunderlich MT, Ebert AD, Kratz T et al. Early neurobehavioral outcome after stroke is related to release of neurobiochemical markers of brain damage. Stroke 1999; 30: 1190±1195. 16 Missler U, Wiesmann M, Ehlermann P et al. Validation and comparison of two solid-phase immunoassays for the quantification of S100B in human blood. Clin Chem 2000; 46: 993±996. 17 Marshak DR. S100B as a neurotrophic factor. Prog Brain Res 1990; 86: 169±181. 18 Mrak RE, Sheng JG, Griffing WST. Glial cytokines in Alzheimer disease. Hum Pathol 1995; 26: 816±823. 19 McAdory BS, Van Eldik LJ, Norden JJ. S100B, a neurotrophic protein that modulates neuronal protein phosphorylation, is upregulated during lesion-
20
21 22
23
19
induced collateral sprouting and reactive synaptogenesis. Brain Res 1998; 813: 211±217. Selinfreund RH, Barger SW, Pledger WJ, Van Eldik LJ. Neurotrophic protein S100B stimulates glial cell proliferation. Proc Natl Acad Sci USA 1991; 88: 3554± 3558. Joseph J, Lublin FD, Knobbler RL. Modulation of Tcell endothelial adhesion by astrocyte conditioned medium. Glia 1997; 21: 408±412. Mecocci P, Parnetti L et al. Serum anti-GFAP and anti-S100 autoantibodies in brain ageing, Alzheimer's disease and vascular dementia. J Neuroimmunol 1995; 57: 165±170. Chao CC, Hu S, Peterson PK. Glia: the not so innocent bystander. J NeuroVirol 1996; 2: 234±239.
ORIGINAL ARTICLE
S100B protein, glia and Gilles de la Tourette syndrome RALPH VAN PASSEL,1 WIM AJM SCHLOOZ,2 KAREL JB LAMERS,3 WIM AJG LEMMENS,4 JAN J ROTTEVEEL1 Departments of 1Paediatric Neurology IKNC, 2Child Psychiatry ACKJON, 3Neurology, 4Statistics, University Hospital Nijmegen, The Netherlands
Activated glial cells play an important role in a variety of neurological disorders. This study examines S100B protein levels in the serum of patients with Gilles de la Tourette syndrome, as potential marker for glial cell function. Two groups of children were examined: 61 reference patients and 33 patients with Gilles de la Tourette syndrome. It was found that S100B serum concentrations in the reference group decrease with increasing age. Furthermore it was found that the mean S100B concentration in serum of children with Gilles de la Tourette syndrome is significantly higher than in the reference group. These preliminary results suggest that glial tissue might be involved in the pathophysiology of the syndrome. Keywords: Gilles de la Tourette syndrome. S100B protein. Glial tissue.
Introduction Gilles de la Tourette syndrome (GTS) is characterized by childhood onset of multiple motor and vocal tics and related somatosensory urges, waxing and waning over time.1,2 Recent reviews summarize pathogenic factors, which have been investigated in GTS.3,4 The effect of e.g. haloperidol suggests involvement of dopaminergic pathways, as does the increased cerebrospinal fluid levels of monoamine transmitter metabolites. Neuroimaging studies suggest that the basal ganglia±thalamocortical pathways may be involved. Magnetic resonance imaging (MRI) studies demonstrate reduced volume and abnormal asymmetries of the caudate, putamen and globus pallidus. In vivo positron emission tomography (PET) research suggests that the reduction in basal ganglia volume is accompanied by decreased basal ganglia metabolism and lower blood flow, as well as reduced glucose rates for the frontal and
cingulate/limbic cortical areas. Recent single photon emission computed tomography (SPECT) investigations have reported increased dopaminetransporter levels in the basal ganglia of GTS patients.3,4 GTS-like symptoms can occur after streptococcal infection or Lyme disease, possibly by the process of molecular mimicry, as seen in paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS).5 Glial tissue has not yet been studied as potential pathogenic factor in GTS. Historically, glia were thought to be merely support cells. There are far more glia±neuron connections than neuron±neuron connections. Astroglial cells are the predominant cell types (85%); microglia (10%) and oligodendrocytes (5%) are the remainder. Glial cells communicate mainly locally or paracrine. Glial cells appear to tightly regulate each other's morphology, activity and secretion of products, through the production of a variety of factors, including cytokines and growth factors.6
Received 15.2.2000. Revised 11.10.2000. Accepted 7.11.2000. Correspondence: Jan J Rotteveel PhD, MD, Department of Paediatric Neurology, University Hospital Nijmegen, PO Box 9101, 6500HB Nijmegen, The Netherlands. e-mail: J.Rotteveel#cksiknc.azn.nl
1090±3798/01/05/0015+5 $35.00
& 2001 European Paediatric Neurology Society
16 A member of a family of calcium-binding proteins, S100 is one of many brain-specific proteins. It binds calcium in cytosol. It is involved in the cell cycle and in interactions in the cytoskeleton and indirectly influences the energy metabolism of the cell. In 1965 Moore isolated a fraction from bovine brains which he believed contained nerve-specific proteins. He called it S100 because it dissolved in 100%-saturated ammonium sulphate.7 The term `S100' refers to a mixture of dimeric proteins consisting of two subunits a and b. Three isoforms are known: S100B (bb) is a multifunctional protein and is present in high concentration in glial cells and Schwann cells of the central and peripheral nervous system; S100A (ab) is present in glial cells but not in Schwann cells; and S100AO (aa) is found exclusively in neurons. S100 can also be found in low concentrations in non-nervous tissues and cells such as adipose tissue, melanocytes and T-lymphocytes.7 S100B is a cerebral marker protein for glial integrity.8 It has been ascertained that the appearance of this protein in blood is a reliable indicator of active glia cell damage in the nervous system in a variety of pathological conditions.9,10 The S100-gene has been located on chromosome 21 (21q22.2-22.3). Triplication of the chromosome in Down syndrome could result in an altered geneexpression of S100B resulting in the neurological conditions associated with the syndrome.11 Overexpressed S100B, as seen in Down syndrome and Alzheimer's disease, was associated with cognitive dysfunction.12 The plasma S100B concentration in healthy adults is age- and sex-independent13 We do not know of any published reference data on plasma S100B protein concentrations in children.
Material and methods Subjects To establish reference values, 35 boys and 26 girls without acute neurological disorders were selected randomly, after parental consent, from the paediatric outpatient clinics. Their age range was 0.2±20.0 years, mean 6.4+5.2 years. Children with acute neurological problems were excluded because of possible effects on the S100B concentration. The patients were divided into two subgroups (IA and IB). Group IA comprised 33 patients without neurological abnormalities: 20 boys and 13 girls, age range 0.2±19.7 years, mean 8.3+4.9 years. Group IB comprised 28 patients with chronic non-progressive neurological abnormalities: 15
Original article: R Van Passel et al. boys and 13 girls, age range 0.5±20.0 years; mean 4.3+4.7 years. Group IB consisted of patients with learning disorders and behavioural problems. Another group (II) consisted of 33 children with GTS: 32 boys and 1 girl, age range 6.2±14.5 years, mean 10.9+2.5 years. The mean age at the time of diagnosis was 10.1 years, range 5.9±14.5 years. The group was restricted to cases of GTS as defined by a multidisciplinary team consisting of a paediatric neurologist, a child psychiatrist and a neuropsychologist. All patients were referred for paediatric movement disorders to the outpatients clinic at the University Hospital. The diagnostic criteria of DSM±IV14 were used. Patients with co-morbid pathology, which might influence the level of S100B, were excluded, e.g. active epilepsy, subacute encephalopathy.
Laboratory investigations Blood samples were taken with informed consent. Protein S100B was assayed using a commercially available monoclonal two-sided immunoluminometric assay kit (Sangtec1 100, Sangtec Medical/ Bromma, Sweden).15,16 The assay kit measures only the b-subunit of the protein S100 as defined by three monoclonal antibodies. Antibody-coated polystyrene tubes serve as solid phase in which the coated monoclonal antibody reacts with the S100B protein in the sample. During a second incubation the tracer antibody binds to the immobilized S100B. The antiS100B tracer conjugate contains a covalently bound isoluminol derivative. For detection the isoluminol is oxidized by alkaline followed by light emission. The whole procedure is performed in an automated LIA-mat system 300 with a detection threshold below 0.02 mg/litre. The recovery rates were between 94±113%. The precision was calculated for concentration ranges in serum from 0.28 to 4.17 mg/litre. The interassay concentration values range from 10.3 to 2.7%. The monoclonal antibodies detect the monomeric S100B and the dimeric isoforms: S100 A1-B and S100 B-B. Monomeric S100 A1 and dimeric isoforms S100 A1-A1 are not detected. It is not exactly known which S100 subtypes (monomeric or dimeric forms) are released in blood in controls and in clinical entities like stroke or malignant melanomas.16 S100B concentrations were determined in serum of the patient.
Statistics The data were entered into a statistical model. After logarithmic transformations, the general
Original article: S100B protein and Gilles de la Tourette syndrome
17
linear model was used to search for age- and/or sex-dependence in the reference group. In further analyses the Student's t-test and Pearson correlation test were used. Regression analysis was performed to yield age-related reference intervals. The median value and reference limits, as the 5th and 95th percentiles, were calculated; p-values for age-dependency were calculated.
Results Reference group The reference group could be divided in two subgroups. Groups IA (without neurological abnormalities) and IB (with chronic non-progressive neurological abnormalities) differed slightly in age, 4.3+4.7 and 8.3+4.9 respectively. The groups IA and IB did not differ on S100B serum concentrations after correction for age. We found no sex dependency. These patients were used as the reference group in the subsequent analyses.
Age dependence In the reference group S100B concentrations in serum show age dependency. In children the concentration of S100B in serum decreases with increasing age (r 70.53) (Fig. 1). Ln (S100B) 71.44±0.071 * age. Residual error: 0.596. Se (intercept) 0.12. Se (slope) 0.015. The p5, p50 and p95 of the S100B concentrations in serum for different ages were calculated (Table 1).
Gilles de la Tourette syndrome In the children with GTS the mean S100B serum concentration is significantly higher than in the reference group (p 0.009) (Fig. 2).
Discussion This study identified a significant increase of the mean S100B serum concentration in children with GTS. The raised S100B serum concentrations might suggest glial tissue involvement. Almost all research on GTS has been focused on neuronal tissue. S100B is a multifunctional protein.8 Disturbance of S100B serum concentrations might lead to a variety of neurological dysfunctions.
Fig. 1. S100B serum concentrations of the reference group against age. Reference area S100B against age with p5, p95 and median p50. Concentration in mg/litre. Closed circles: with chronic non-progressive neurological abnormalities. Open circles: without neurological abnormalities.
S100B is secreted by proliferating astrocytes, particularly during neurite outgrowth from cortical cells.17 S100B is seen early in the development of the fetal brain and seems to be an important neurotrophic agent, affecting neuroblasts and glia.12 S100B also has autocrine effects as a stimulant of astrocyte proliferation. It can promote, in tissue culture studies, the extension of serotonergic neurites18 and it plays a role in lesioninduced collateral sprouting and reactive synaptogenesis.19 S100B may be involved in the coordinated development and maintenance of the central nervous system by synchronously stimulating the differentiation of neurons and the proliferation of astroglia.20 A slight increase in concentration of S100B might reflect a disturbance in the development and maintenance of the integrity of the central nervous system. Astroglial cells are an active part of the blood±brain barrier. Astrocytes and derived factors maintain the morphologic, phenotypic and physiological properties of the blood±brain barrier. Astroglial cells may also modulate endothelial cell properties Table 1 S100B (mg/litre) in the reference group for different ages. Age (years) 0 3 6 9 12 15 18
p5
p50
p95
0.089 0.072 0.058 0.047 0.038 0.031 0.025
0.237 0.191 0.154 0.125 0.101 0.081 0.066
0.630 0.510 0.412 0.333 0.269 0.217 0.175
18
Original article: R Van Passel et al.
Acknowledgements We thank Dr W Gerrits for collecting the laboratory samples, ACAM van der Pijll for her neuropsychological analyses, HPM de Reus and WJA van Geel for their laboratory support, and Dr AW Sloman for his linguistic corrections.
References Fig. 2. S100B serum concentrations of the GTS group against age. With p5, p95 and median p50 of the reference group. Concentration in mg/litre.
associated with the entry of inflammatory cells into the brain.21 This is interesting, because GTS-like symptoms can occur after streptococcal infection or Lyme disease.5 Antineural antibodies are elevated in some patients with GTS.5 The presence of antibodies may reflect an alteration of the blood± brain barrier that allows central nervous system antigens access to immunocompetent cells.22. Dysfunctioning of glial tissue might result in alterations in the blood±brain barrier. Glia are involved in neurotransmission; they store and release neurotransmitters and nutrients. Activated glial cells play an important role in a number of neurodegenerative diseases. This activation is marked by hypertrophy and results in the expression of structural proteins, adhesion molecules, antigens and cytokines, such as S100B, all capable of contributing to neuronal damage.23 Reactive glial cells act as an opposing force to neurotrophic astroglia, competing to regulate the survival of neurons.6 Thus, dysfunction in glial tissue could alter a number of regulatory systems. The delicate interaction that exists between glial cells and neurons is crucial for the maintenance of neuronal functioning and integrity.6 Dysfunctioning of glial tissue could alter this balance. S100B serum concentrations are age-dependant in the paediatric age group. A remarkable difference is found between the S100B concentrations in serum and in liquor. In liquor the S100B concentration increases with age.9,10 In serum the S100B concentrations decreases with age. The mechanism of this effect is thus far unknown. The elevation of the mean S100B concentration in GTS is noteworthy and the observation justifies further research into the possible role of glial tissue in the pathogenesis of GTS.
1 Cohen DJ, Leckman JF. Developmental psychopathology and neurobiology of Tourette's syndrome. J Am Acad Child Adoles Psychiat 1994; 35: 245±250. 2 Robertson MM. Annotation. Gilles de la Tourette syndrome ± An update. J Child Psychol Psychiat 1994; 35: 597±611. 3 Sheppard DM, Bradshaw JL. Tourette's and comorbid syndromes: Obsessive compulsive and attention deficit hyperactivity disorder. A common aetiology? Clin Psych Rev 1999; 19: 531±552. 4 Leckman JF, Pauls DL, Peterson BS et al. Pathogenesis of Tourette's syndrome. J Child Psychol Psychiat 1997; 38: 119±142. 5 Singer HS, Guiliano JD et al. Antibodies against human putamen in children with Tourette's syndrome. Neurology 1998; 50: 1618±1624. 6 Vincent VAM, Tildes FJH, Van Dam A-M. Production, regulation and role of nitric oxide in glial cells. Med Inflammat 1998; 7: 239±255. 7 Zimmer DB, et al. The S100 protein family: History, function and expression. Brain Res Bull 1995; 37: 417± 429. 8 Michetti F, Massoro A, Russo G, Rigon O. The S100 antigen in cerebrospinal fluid as a possible index of cell injury in the nervous system. J Neurol Sci 1980; 44: 731±743. 9 Persson L, Hardemark HG, Gustafson J et al. S100 protein and neuron-specific-enolase in cerebrospinal fluid and serum: markers of cell damage in human central nervous tissue. Stroke 1987; 18: 911±918. 10 Lamers KJB, van Engelen BGM, Gabreels FJM, et al. Cerebrospinal neuron-specific enolase, S100 and myelin basic protein in neurologic disorders. Acta Neurol Scand 1995; 92: 247±251. 11 Marks A, Allore R. S100 protein and Down's syndrome. Bioassays 1990; 12: 381±383. 12 Fwu-Shan Sheu et al. Glial-derived S100b protein selectively inhibits recombinant B protein kinase c phosphorylation of neuron specific protein F1/ GAP43. Mol Brain Res 1994; 21: 62±66. 13 Wiesmann 1, Missler U, Gottmann D, Gehring S. Plasma S100B protein concentration in healthy adults is age- and sex-independent. Clin Chem 1998; 44: 1056±1058. 14 American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (DSM±IV), American Psychiatric Association: Washington DC, 1994.
Original article: S100B protein and Gilles de la Tourette syndrome 15 Wunderlich MT, Ebert AD, Kratz T et al. Early neurobehavioral outcome after stroke is related to release of neurobiochemical markers of brain damage. Stroke 1999; 30: 1190±1195. 16 Missler U, Wiesmann M, Ehlermann P et al. Validation and comparison of two solid-phase immunoassays for the quantification of S100B in human blood. Clin Chem 2000; 46: 993±996. 17 Marshak DR. S100B as a neurotrophic factor. Prog Brain Res 1990; 86: 169±181. 18 Mrak RE, Sheng JG, Griffing WST. Glial cytokines in Alzheimer disease. Hum Pathol 1995; 26: 816±823. 19 McAdory BS, Van Eldik LJ, Norden JJ. S100B, a neurotrophic protein that modulates neuronal protein phosphorylation, is upregulated during lesion-
20
21 22
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