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Increased serum S100B in never-medicated and medicated schizophrenic patients
Journal of Psychiatric Research 44 (2010) 1236e1240
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Increased serum S100B in never-medicated and medicated schizophrenic patients Xiang Yang Zhang a, b, c, *,1, Mei Hong Xiu b,1, Cai Song d, Da Chun Chen b, Gui Ying Wu c, Colin N. Haile c, Therese A. Kosten c, Thomas R. Kosten c, ** a
Institute of Psychology, Chinese Academy of Sciences, Beijing, PR China Center for Biological Psychiatry, Beijing Hui Long Guan Hospital, Beijing, PR China c Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, Texas, USA d Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 January 2010 Received in revised form 6 April 2010 Accepted 20 April 2010
S100B is a calcium-binding protein, which is produced primarily by glial cells. It modulates the proliferation and differentiation of neurons and glia by affecting protective and apoptotic mechanisms. Recently, several studies have shown increased serum S100B levels in patients with schizophrenia, suggesting that S100B might be relevant to the pathophysiology of schizophrenia. S100B levels were assessed using ELISA in the serum of 80 never-medicated early-stage and 82 medicated chronic schizophrenia patients and 97 healthy controls subjects. The psychopathology of schizophrenia was assessed by the Positive and Negative Syndrome Scale (PANSS). Our results showed significantly increased serum S100B levels in both never-medicated and medicated patients compared to normal controls (both p < 0.0001). S100B in never-medicated patients was also markedly increased, compared with medicated patients (p < 0.0001). S100B changes observed were irrespective of neuroleptic medication, gender, age, and smoking. Increased S100B levels in the early stage of schizophrenia suggest that glial cell activation or structural damage may be part of a neurodegenerative process in schizophrenia. The lower S100B levels in chronic than early-stage patients further suggest that antipsychotic treatment may reduce this neurodegeneration. Ó 2010 Elsevier Ltd. All rights reserved.
Keywords: Schizophrenia S100B Early psychosis Antipsychotic treatment Psychopathology
1. Introduction The S100B protein (S100B) is a calcium-binding protein, mainly produced and secreted by astrocytes that exert paracrine and autocrine effects on neurons and glia. It achieves this by regulating a variety of cellular mechanism such as proliferation, differentiation, cellular energy metabolism and cytoskeletal modification through mediating phosphorylation of key synaptic proteins (Donato, 2001; Sen and Belli, 2007). Interestingly, secreted glial S100B exerts either trophic or toxic effects depending on its concentration with nanomolecular concentrations being * Corresponding author at: VA Medical Center, Research Building 109, Room 130, 2002 Holcombe Boulevard, Houston, Texas, 77030, USA. Tel.: þ1 7137911414x5824; fax: þ1 713 794 7938. ** Corresponding author at: VA Medical Center, Research Building 110, Room 229, 2002 Holcombe Boulevard, Houston, Texas, 77030, USA. Tel.: þ1 7137947032; fax: þ1 713 794 7938. E-mail addresses: [email protected] (X.Y. Zhang), [email protected] (T.R. Kosten). 1 These two authors (Xiang Yang Zhang and Mei Hong Xiu) contributed equally to this study. 0022-3956/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpsychires.2010.04.023
neuroprotective whereas micromolecular concentrations promote apoptosis (Rothermundt et al., 2003, 2004a), thus is viewed as a marker of structural damage, or increased active synthesis and release (Steiner et al., 2006, 2008b; van Beveren et al., 2006). Although S100B has been regarded a marker of astroglial cellular integrity, yet S100B is also expressed in other neural cells such as oligodendrocytes (Steiner et al., 2006, 2008a) and is detected outside the central nervous system (CNS) (Steiner et al., 2007), such as in adipocytes (Steiner et al., 2010a,b). Most studies have shown that S100B is increased in cerebrospinal fluid (CSF) and serum of schizophrenic patients, especially during acute stages of the disease with persistently high S100B levels positively associated with negative or deficit symptoms (Rothermundt et al., 2001, 2004a,b; Sarandol et al., 2007; Holtkamp et al., 2008; Tan et al., 2010), with only a few exceptions (Schmitt et al., 2005). A recent histological study has also shown that cortical brain regions contained more S100B-immunopositive glia in the schizophrenia group relative to controls, particularly in dorsolateral prefrontal (DLPF) brain area (Steiner et al., 2008b). Furthermore, two most recent meta-analyses have shown consistently higher S100B in schizophrenia patients (Schroeter et al.,
X.Y. Zhang et al. / Journal of Psychiatric Research 44 (2010) 1236e1240
2009; Schroeter and Steiner, 2009). Antipsychotic medications alleviate-to an extent- schizophrenic symptoms. Thus, studies have attempted to link antipsychotic therapeutic action to effects on S100B with conflicting results. For example, patients receiving typical or atypical antipsychotic drugs in comparison to unmedicated patients showed higher levels of S100B (Schroeter et al., 2003), whereas others found no influence of medication (Sarandol et al., 2007). Still, some authors observed that treatment with antipsychotic drug treatment for several weeks normalized S100B levels (Rothermundt et al., 2001, 2004b). These studies suggest that S100B might be relevant in the pathophysiology of schizophrenia. One recent study showed increased S100B levels in first-episode and drug-naïve schizophrenic patients (Tan et al., 2010). However, no studies have compared S100B levels in drug-naïve and medicated schizophrenic patients. The present study therefore examined three issues: (1) Are serum S100B levels altered in never-medicated early-stage psychotic patients at the onset of psychosis compared to normal controls and to chronic medicated schizophrenic patients? (2) Is there a difference in the effects of typical and atypical antipsychotics on S100B levels? (3) Are S100B levels related to psychopathological symptoms in never-medicated and medicated schizophrenic patients?
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Normal controls (97; male/female ¼ 59/38) were recruited from the local community. None of them had a personal or family history of psychiatric disorder, and all were Han Chinese from the Beijing area. Table 1 summarizes the demographics for patients and normal controls. All patients and control subjects were in good physical health, and any subjects with major medical illnesses or drug and alcohol abuse/dependence were excluded. All subjects gave written informed consent, which was approved by the Institutional Review Board of Beijing HuiLongGuan hospital. 2.2. Serum S100B measurements Serum samples were collected between 07.00 and 09.00 h following an overnight fast. Serum S100B levels were measured in duplicate in all subjects by sandwich ELISA using a commercially available kit (R&D systems, Beijing, China). A full description of the assays has been given in our previous report (Qi et al., 2009). All samples were assayed by the same investigator, who was blind to the clinical situation. The sensitivity of the assay was 0.1 ng/ml. Inter- and intra-assay variation coefficients were 6% and 4%, respectively. 2.3. Psychopathological assessment in patients
2. Methods 2.1. Subjects We recruited 80 (male/female ¼ 42/38) never-medicated and early-stage patients meeting DSM-IV criteria for schizophrenia from consecutive admissions at the inpatient unit of Beijing HuiLongGuan hospital, a Beijing city-owned psychiatric hospital. All patients were reassessed and confirmed after 3-month follow-up. Their clinical subtypes were: paranoid, 41 (51.2%), undifferentiated, 31 (38.8%); disorganized 6 (7.5%); others 2 (2.5%). Eighty two chronic medicated schizophrenic patients (male/ female ¼ 57/25) were also introduced into the study at the same hospital. Both never-medicated and medicated patients were diagnosed by two independent and experienced psychiatrists and confirmed by the Structured Clinical Interview for DSM-IV (SCID). The chronic patients had a mean illness course of 26.6 8.7 years with 8.7 6.8 years of hospitalization. They were receiving stable doses of oral neuroleptics for at least 12 months including clozapine (n ¼ 31), risperidone (n ¼ 22), perphenazine (n ¼ 9), haloperidol (n ¼ 8), chlorpromazine (n ¼ 6), and sulpiride (n ¼ 6). Their clinical subtypes were: 36 paranoid (43.9%), 10 disorganized (12.2%), 4 undifferentiated (4.9%) and 32 residual types (39.0%).
Four psychiatrists, who were blind to the clinical status and treatment condition, assessed the patient’s psychopathology using the Positive and Negative Syndrome Scale (PANSS) on the day of the blood sampling. To ensure consistency and reliability of rating across the study, these four psychiatrists who had worked at least 5 years in clinical practice, were trained in using the PANSS before the start of the study. After training a correlation coefficient greater than 0.8 was maintained for interrater reliability on the PANSS total score at repeated assessments during the study. 2.4. Statistical analysis We compared the S100B levels in the never-medicated and medicated patient and control groups using a univariate analysis of covariance (ANCOVA) with gender, age and smoking as covariates. Post hoc comparisons between groups were made using the Bonferroni procedure. Furthermore, univariate analysis of variance (ANOVA) and ANCOVA were also used to compare between-group differences. Bonferroni corrections were applied to each test to adjust for multiple testing. Psychopathology on the PANSS was compared between the patient groups by one-way ANOVA and correlated with S100B levels within patient groups by calculating
Table 1 Demographic data in never medicated and early-stage, chronic schizophrenia patients and control groups.
Male/Female Age (yrs) Cigarette smoking Male Female Duration of Illness (yrs) PANSS total P subscore N subscore G subscore S100B (ng/ml)
Never-medicated (n ¼ 80)
Medicated patients (n ¼ 82)
Normal control (n ¼ 97)
p value
42/38 29.1 9.6 22 (28%) 19 (86%) 3 (14%) 2.1 1.9 83.4 18.9 25.6 6.2 18.4 7.2 39.7 11.5 0.541 0.214***, ###
57/25 50.9 7.0 50 (61%) 48 (96%) 2 (4%) 26.6 8.7 58.4 13.2 12.4 6.0 19.8 6.5 26.1 5.4 0.351 0.116###
59/38 37.9 9.0 33 (34%) 28 (85%) 5 (15%) NA NA NA NA NA 0.122 0.076
ns <0.001 <0.001
<0.001 <0.001 <0.001 ns <0.001 <0.001
Note: * indicates the comparison between never medicated and early-stage and medicated chronic patients. *** p < 0.001. # indicates the comparison between patients and normal controls. ###p < 0.001. Abbreviations: PANSS ¼ the Positive and Negative Syndrome Scale; P ¼ positive symptom; N ¼ negative symptom; G ¼ general psychopathology; S100B ¼ the S100B protein.
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Pearson correlation coefficients. Stepwise multiple regression analysis using S100B as dependent variable was performed to investigate the impact of age, gender, duration of illness, age of onset and psychopathological symptoms shown by PANSS and its subscales. Two-tailed significance values were used and significance levels were set at 0.05. 3. Results Table 1 shows the demographic data of the subjects included in the study. Never-medicated, medicated patients and control subjects significantly differed in age (p < 0.001) and smoking (p < 0.001), and duration of illness between never-medicated and medicated patients (p < 0.001). A possible influence of age on S100B was investigated calculating Pearson correlation coefficients between S100B and age in control subjects. Statistical analysis here revealed no influence of age on S100B in normal controls (r ¼ 0.11, ns). Gender distribution was not different between groups (X2 ¼ 4.93, df ¼ 2, p ¼ 0.09) (Table 1). To analyze gender as potential co-variable of the target parameter (S100B), univariate ANOVA was performed in the whole group, or when the normal controls and patients (never-medicated and medicated) were examined separately. There was no influence of gender on S100B levels (all p > 0.05). 3.1. Serum S100B levels Serum S100B levels were significantly different among nevermedicated patients, medicated patients and normal control groups when age was added as a covariate [F(2,256) ¼ 119.1, p < 0.0001]. Furthermore, when gender and smoking were added as additionally confounding covariate terms, the differences between the patients and controls remained significant [F(5,256) ¼ 154.6, p < 0.0001]. Post hoc comparisons using the Bonferroni procedure showed significantly increased S100B in never-medicated patients and medicated patients compared to normal controls (both p < 0.0001). Furthermore, significant increase in S100B was observed in never-medicated patients compare to medicated patients (p < 0.0001) (Table 1; Fig. 1). In addition, separate group comparisons of S100B among these three groups using ANCOVA with age, sex and smoking behavior as covariate terms still showed similar results (all p < 0.0001). 0.8
Furthermore, separate group comparisons of S100B within the patient sample using univariate ANOVA showed a highly significant difference in S100B between never-medicated and medicated patients [Fig. 1; F(1,160) ¼ 46.6, p < 0.0001]. When age, sex, duration of illness and smoking were added as potentially confounding covariate terms, the differences remained significant (p < 0.0001). In addition, correlation analysis did not reveal significant influence of age or duration of illness on S100B in never-medicated and medicated patients separately (all p > 0.05). 3.2. Psychopathology and S100B There were significant differences between the never-medicated and medicated patients on the PANSS total, positive and general psychopathology (all p < 0.001), but not negative scores (P > 0.05) (Table 1). Correlation analysis of data from all patients showed that S100B levels were not associated with any psychopathological parameters (all p > 0.05). Furthermore, separate correlation analysis showed that S100B levels were not associated with any psychopathological parameters within either the nevermedicated or medicated groups of patients (all p > 0.05). Stepwise multiple regression analysis including PANSS and its subscales, age, gender, duration of illness, age of onset and smoking and S100B levels (as dependent variable) in patient groups did not identify any variables as the influencing factors for S100B (p > 0.05). 3.3. Other confounding factors Other possible confounding factors in the differences in S100B levels included cigarette smoking, and antipsychotic agent type, current mean dose over one month before the start of the study, and duration of treatment. Cigarette smoking differed among groups (p < 0.001), with more chronic patients smoking (61%), than normal controls (34%) or early-stage patients (28%). As a whole, S100B levels did not differ between cigarette smokers and non-smokers, or when the normal controls and patients (never-medicated and medicated) were examined separately (all p > 0.05). Among the chronic patients S100B levels were not significantly affected by typical vs. atypical neuroleptics, dose or duration of antipsychotic treatment (all p > 0.05). Furthermore, no significant difference in S100B was noted between clozapine (n ¼ 31) risperidone (n ¼ 22) and typical antipsychotic (n ¼ 29) subgroups (all p > 0.05).
S100B (ng/ml)
4. Discussion
0.4
0
NC
CMP
DNP
Fig. 1. Serum S100B in drug-naïve patients (DNP) with schizophrenia (n ¼ 80), chronic medicated patients (CMP) with schizophrenia (n ¼ 82) and normal controls (NC) (n ¼ 97). The sample means are indicated by the black bars. S100B levels were significantly higher in both first episode patients and chronic patients than normal controls (both p < 0.001). S100B in first-episode patients was also markedly increased compared with chronic patients (p < 0.0001).
Our results show that S100B is significantly elevated in drugnaïve early-stage schizophrenic patients. These levels were also significantly greater compared to medicated chronic schizophrenic patients. Increased serum S100B levels in our early-stage drugnaïve schizophrenic patients are consistent with that seen in younger (Rothermundt et al., 2004a) or elderly chronic schizophrenic patients (Schmitt et al., 2005) as well as neuroleptic-free and medicated patients in an acute stage of disease (Gattaz et al., 2000; Rothermundt et al., 2001; Schroeter et al., 1999, 2003; Sarandol et al., 2007; Pedersen et al., 2008).In contrast, Gattaz et al. and Schroeter et al. failed to find any difference in serum levels of S100B in schizophrenic patients (Gattaz et al., 2000; Schroeter et al., 2003). However, differences in measurement techniques, testing material (CSF vs. plasma vs. serum), exposure to neuroleptic treatment (naive vs. medicated or drug withdrawal vs. medicated), sampling of patients in different stages of disease progression (acute vs. chronic or active phase vs. remission), different duration of illness, different ethnic origin, and duration of sample storage, may be responsible for these conflicting results.
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The source of circulating S100B remains unclear. Although S100B is predominantly expressed in astrocytes, it is also present in other brain cells such as oligodendrocytes, microglial or even neuronal cells (Steiner et al., 2007). There is evidence that oligodendrocytes independently produce S100B (Steiner et al., 2008a,b). Also, there is a large body of evidence for an affection of oligodendrocytes in schizophrenia, e.g. post-mortem studies (Uranova et al., 2004, 2007; Schmitt et al., 2009; Farkas et al., 2010), or microarray studies (Tkachev et al., 2003). Furthermore, no study has tested whether astrocytes produce more S100B than oligodendrocytes in human brain, and what S100B concentrations are in the brain in schizophrenia. Also, extracerebral sources of S100B have been described such as in adipose tissue, lymphocytes, melanocytes, the myocardium, vascular endothelial/smooth muscle cells, satellite cells of dorsal root ganglia, and Schwann cells of peripheral nervous system (Donato, 2001; Steiner et al., 2007, 2008a, 2010a,b). However, blood levels of S100B are unlikely to result from peripheral sources, since it is found predominantly in the cytosol of brain glial cells and may leak from structurally damaged glial cells into the CSF and then into the blood, particularly through the permeable blood brain barrier of schizophrenia (Steiner et al., 2006). In healthy controls S100B serum measures reliably reflect S100B concentrations in the CSF (Nygaard et al., 1997). Both S100B CSF and blood levels correlate with the clinical severity of damage to the CNS (Lamers et al., 1995; Wiesmann et al., 1997) and neurological diseases that increase CSF S100B concurrently increase peripheral blood S100B (van Beveren et al., 2006). Elevated S100B serum levels are associated with increased myo-inositol concentrations in schizophrenics’ brains (Rothermundt et al., 2007). It is presumed that elevated serum S100B in schizophrenic patients reflects central damage because physical myelin integrity is restored in patients that respond to antipsychotic medications (Garver et al., 2008). On the other hand, a recent histological study has shown that cortical brain regions contained more S100B-immunopositive glia in the schizophrenia group relative to controls. Moreover, the white matter of patients with paranoid schizophrenia contained more (mainly oligodendrocytic) S100B-positive glia as compared to residual schizophrenia. Their results suggest that astro-/oligodendroglial activation may result in increased cellular S100B in paranoid schizophrenia. On the contrary, residual schizophrenia may be caused by white matter oligodendroglial damage or dysfunction, associated with a release of S100B into body fluids (Steiner et al., 2008b). Taken together, increased S100B in drug-naïve early-stage schizophrenic patients in our present study indicates that structurally damaged or activated glial cells associated with release of S100B may be part of a neurodegenerative process during the early stage of schizophrenia, suggesting a role in the pathogenesis of illness. Furthermore, we found lower S100B levels in chronic schizophrenic patients treated for several years with antipsychotics compared to never-medicated early-stage patients. This suggests another therapeutic mechanism of antipsychotic medications. Two previous studies found increased S100B serum levels during the initial phase of schizophrenic psychoses followed by normalization of these levels during the chronic stage of illness (Rothermundt et al., 2001; Ling et al., 2007). This effect however appears to be selective for patients with predominantly positive symptoms because elevated levels of circulating S100B persists in those patients with negative symptomology even after antipsychotic treatment (Rothermundt et al., 2001, 2004a,b). In contrast, other reports show low S100B plasma levels in schizophrenic outpatients, mostly treated with clozapine (Gattaz et al., 2000), and in unmedicated schizophrenic patients compared to patients receiving antipsychotic medication for about 3 weeks (Schroeter et al., 2003). The authors suggest that antipsychotics may initially increase S100B during the early phase of treatment, and then after
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a month or more antipsychotics may decrease S100B in patients with relatively few negative symptoms (Schroeter et al., 2003). However, in our present study, S100B levels of clozapine-treated patients were not different from those patients on risperidone and typical antipsychotic medication treatment. Although we did not assess the possibility if S100B levels are altered in earlystage schizophrenic patients in response to antipsychotic medication studies directly assessing this possibility are warranted to clarify the temporal aspects of S100B in the pathogenesis of this disease. Several points should be noted here. First, the measurement of S100B levels resulted in about 2e4 times higher levels in controls and schizophrenia subjects in our current study than in most previous studies (Schroeter et al., 2009). This difference in S100B levels in subjects is most likely due to the assay employed, especially the differences in the sensitivity/specificity. Another possible explanation is that there are significant differences in S100B genotype frequencies observed in different populations. Recent studies have shown an ethnicity-based variability in the allelic frequency and genotype inheritance patterns for S100B (Liu et al., 2005), suggesting that polymorphisms within S100B genes may be responsible for the ethnic-based differences in S100B levels. Unfortunately, there is no direct comparison study yet on the S100B genotype between Chinese and Caucasians. Second, we examined our patients only once in a cross-sectional rather than longitudinal comparison between naive and long term medicated states. Third, serum S100B differences may be related to severe stress (Scaccianoce et al., 2004), such as that experienced by our early-stage unmedicated psychotic patients. Further studies will need to evaluate the role of stress on S100B perhaps through measuring hormone levels related to the hypothalamicepituitaryeadrenal (HPA) axis. Fourth, most recently, it has been shown that S100B is related to body-mass-index (BMI) and insulin resistance (Steiner et al., 2010a,b), which is also relevant for patients suffering from schizophrenia, due to the increased prevalence of metabolic syndrome, and weight gain and obesity in schizophrenia on antipsychotic pharmacotherapy (Correll and Malhotra, 2004). Unfortunately, we did not control for BMI in the present study. Hence, whether the increased S100B in schizophrenia in our present study is caused by increased weight gain and metabolic syndrome cannot be ruled out, which deserves further investigation. In conclusion, serum S100B is significantly elevated in both never-medicated early-stage and medicated patients with chronic schizophrenia, which supports activation or damage of glial cells, especially astrocytes as a contributor to the pathogenesis of schizophrenia (Lamers et al., 1995). Antipsychotic treatment probably accounts for the lower S100B levels in medicated chronic schizophrenic patients than in unmedicated early-stage patients. Thus, these results support the notion that schizophrenic patients appear to be suffering ongoing activation or structural damage to glial cells, particularly to astrocytes and antipsychotics may attenuate this process contributing to therapeutic efficacy (Schafer and Heizmann, 1996; Wiesmann et al., 1999). Role of the funding source This study was funded by the Beijing Municipal Natural Science Foundation (ID: 7072035), the Stanley Medical Research Institute (03T-459 and 05T-726), and the Department of Veterans Affairs, VISN 16, Mental Illness Research, Education and Clinical Center (MIRECC), United States National Institute of Health K05-DA0454, P50-DA18827 and U01-MH79639. These sources had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.
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Contributors Xiang Yang Zhang and Mei Hong Xiu were responsible for study design, statistical analysis, and manuscript preparation. Mei Hong Xiu and Da Chun Chen were responsible for recruiting the patients, performing the clinical rating and collecting the samples. Cai Song, Gui Ying Wu, Colin Haile, and Therese Kosten were involved in evolving the ideas and editing the manuscript. Thomas Kosten was involved in writing the protocol, cowrote the paper and was responsible for providing the funding for the study. All authors have contributed to and have approved the final manuscript. Conflict of interest The authors have no conflicts to disclose. References Correll CU, Malhotra AK. Pharmacogenetics of antipsychotic-induced weight gain. Psychopharmacology (Berl) 2004;174(4):477e89. Donato R. S100: a multigenic family of calcium-modulated proteins of the EFhand type with intracellular and extracellular functional roles. The International Journal of Biochemistry & Cell Biology 2001;33:637e68. Farkas N, Lendeckel U, Dobrowolny H, Funke S, Steiner J, Keilhoff G, et al. Reduced density of ADAM 12-immunoreactive oligodendrocytes in the anterior cingulate white matter of patients with schizophrenia. World Journal of Biological Psychiatry 2010;11(3):193e203. Garver DL, Holcomb JA, Christensen JD. Compromised myelin integrity during psychosis with repair during remission in drug-responding schizophrenia. International Journal of Neuropsychopharmacology 2008;11:49e61. Gattaz WF, Lara DR, Elkis H, Portela LV, Gonçalves CA, Tort AB, et al. Decreased S100beta protein in schizophrenia: preliminary evidence. Schizophrenia Research 2000;43:91e5. Holtkamp K, Buhren K, Ponath G, von Eiff C, Herpertz-Dahlmann B, Hebebrand J, et al. Serum levels of S100B are decreased in chronic starvation and normalize with weight gain. Journal of Neural Transmission 2008;115:937e40. Lamers KJ, van Engelen BG, Gabreels FJ, Hommes OR, Borm GF, Wevers RA. Cerebrospinal neuron-specific enolase, S-100 and myelin basic protein in neurological disorders. Acta Neurologica Scandinavica 1995;92:247e51. Ling SH, Tang YL, Jiang F, Wiste A, Guo SS, Weng YZ, et al. Plasma S-100B protein in Chinese patients with schizophrenia: comparison with healthy controls and effect of antipsychotics treatment. Journal of Psychiatric Research 2007;41:36e42. Liu J, Shi Y, Tang J, Guo T, Li X, Yang Y, et al. SNPs and haplotypes in the S100B gene reveal association with schizophrenia. Biochemical and Biophysical Research Communications 2005;328(1):335e41. Nygaard O, Langbakk B, Romner B. Age- and sex-related changes of S-100 protein concentrations in cerebrospinal fluid and serum in patients with no previous history of neurological disorder. Clinical Chemistry 1997;43:541e3. Pedersen A, Diedrich M, Kaestner F, Koelkebeck K, Ohrmann P, Ponath G, et al. Memory impairment correlates with increased S100B serum concentrations in patients with chronic schizophrenia. Progress in Neuro-Psychopharmacology and Biological Psychiatry 2008;32:1789e92. Qi LY, Xiu MH, Chen da C, Wang F, Kosten TA, Kosten TR, et al. Increased serum S100B levels in chronic schizophrenic patients on long-term clozapine or typical antipsychotics. Neuroscience Letters 2009;462(2):113e7. Rothermundt M, Missler U, Arolt V, Peters M, Leadbeater J, Wiesmann M, et al. Increased S100B blood levels in unmedicated and treated schizophrenic patients are correlated with negative symptomatology. Molecular Psychiatry 2001;6:445e9. Rothermundt M, Peters M, Prehn JH, Arolt V. S100B in brain damage and neurodegeneration. Microscopy Research and Technique 2003;60:614e32. Rothermundt M, Ponath G, Glaser T, Hetzel G, Arolt V. S100B serum levels and long term improvement of negative symptoms in patients with schizophrenia. Neuropsychopharmacology 2004a;29:1004e11. Rothermundt M, Falkai P, Ponath G, Abel S, Bürkle H, Diedrich M, et al. Glial cell dysfunction in schizophrenia indicated by increased S100B in the CSF. Molecular Psychiatry 2004b;9:897e9. Rothermundt M, Ohrmann P, Abel S, Siegmund A, Pedersen A, Ponath G, et al. Glial cell activation in a subgroup of patients with schizophrenia indicated by
increased S100B serum concentrations and elevated myo-inositol. Progress in Neuro-Psychopharmacology and Biological Psychiatry 2007;30:361e4. Sarandol A, Kirli S, Akkaya C, Altin A, Demirci M, Sarandol E. Oxidative/antioxidative systems and their relation with serum S100 B levels in patients with schizophrenia: effects of short term antipsychotic treatment. Progress in NeuroPsychopharmacology and Biological Psychiatry 2007;31:1164e9. Scaccianoce S, Del Bianco P, Pannitteri G, Passarelli F. Relationship between stress and circulating levels of S100B protein. Brain Research 2004;1004:208e11. Schafer BW, Heizmann CW. The S100 family of EF-hand calcium-binding proteins: functions and pathology. Trends in Biochemical Sciences 1996;21:134e40. Schmitt A, Bertsch T, Henning U, Tost H, Klimke A, Henn FA, et al. Increased serum S100B in elderly, chronic schizophrenic patients: negative correlation with deficit symptoms. Schizophrenia Research 2005;80:305e13. Schmitt A, Steyskal C, Bernstein HG, Schneider-Axmann T, Parlapani E, Schaeffer EL, et al. Stereologic investigation of the posterior part of the hippocampus in schizophrenia. Acta Neuropathologica 2009;117:395e407. Schroeter ML, Mertsch K, Giese H, Müller S, Sporbert A, Hickel B, et al. Astrocytes enhance radical defence in capillary endothelial cells constituting the bloodebrain barrier. FEBS Letters 1999;49:241e4. Schroeter ML, Abdul-Khaliq H, Frühauf S, Höhne R, Schick G, Diefenbacher A, et al. Serum S100B is increased during early treatment with antipsychotics and in deficit schizophrenia. Schizophrenia Research 2003;(62):231e6. Schroeter ML, Abdul-Khaliq H, Krebs M, Diefenbacher A, Blasig IE. Neuron-specific enolase is unaltered whereas S100B is elevated in serum of patients with schizophrenia e original research and meta-analysis. Psychiatry Research 2009;167:66e72. Schroeter ML, Steiner J. Elevated serum levels of the glial marker protein S100B are not specific for schizophrenia or mood disorders. Molecular Psychiatry 2009;14:235e7. Sen J, Belli A. S100B in neuropathologic states: the CRP of the brain? Journal of Neuroscience Research 2007;85:1373e80. Steiner J, Bielau H, Bernstein HG, Bogerts B, Wunderlich MT. Increased cerebrospinal fluid and serum levels of S100B in first-onset schizophrenia are not related to a degenerative release of glial fibrillar acidic protein, myelin basic protein and neurone-specific enolase from glia or neurones. The Journal of Neurology, Neurosurgery, and Psychiatry 2006;77:1284e7. Steiner J, Bernstein HG, Bielau H, Berndt A, Brisch R, Mawrin C, et al. Evidence for a wide extra-astrocytic distribution of S100B in human brain. BMC Neuroscience 2007;8:2. Steiner J, Bernstein HG, Bogerts B, Gos T, Richter-Landsberg C, Wunderlich MT, et al. S100B is expressed in, and released from, OLN-93 oligodendrocytes: Influence of serum and glucose deprivation. Neuroscience 2008a;154:496e503. Steiner J, Bernstein HG, Bielau H, Farkas N, Winter J, Dobrowolny H, et al. Bogerts, B. S100B-immunopositive glia is elevated in paranoid as compared to residual schizophrenia: a morphometric study. Journal of Psychiatric Research 2008b;42:868e76. Steiner J, Schiltz K, Walter M, Wunderlich MT, Keilhoff G, Brisch R, et al. S100B serum levels are closely correlated with body mass index: an important caveat in neuropsychiatric research. Psychoneuroendocrinology 2010a;35:321e4. Steiner J, Walter M, Guest P, Myint AM, Schiltz K, Panteli B, et al. Elevated S100B levels in schizophrenia are associated with insulin resistance. Molecular Psychiatry 2010b;15(1):3e4. Tan Y, Luo X, Yang F, Zhang W, Wang Z, Zou Y, et al. Elevated serum S100B protein in first-episode drug-naïve Chinese patients with schizophrenia. Schizophrenia Research; 2010 Feb 16 [Epub ahead of print]. Tkachev D, Mimmack ML, Ryan MM, Wayland M, Freeman T, Jones PB, et al. Oligodendrocyte dysfunction in schizophrenia and bipolar disorder. Lancet 2003;362(9386):798e805. Uranova NA, Vostrikov VM, Orlovskaya DD, Rachmanova VI. Oligodendroglial density in the prefrontal cortex in schizophrenia and mood disorders: a study from the Stanley Neuropathology Consortium. Schizophrenia Research 2004;67:269e75. Uranova NA, Vostrikov VM, Vikhreva OV, Zimina IS, Kolomeets NS, Orlovskaya DD. The role of oligodendrocyte pathology in schizophrenia. International Journal of Neuropsychopharmacology 2007;10(4):537e45. van Beveren NJ, van der Spelt JJ, de Haan L, Fekkes D. Schizophrenia-associated neural growth factors in peripheral blood. A review. European Neuropsychopharmacology 2006;16:469e80. Wiesmann M, Missler U, Hagenstrom H, Gottmann D. S-100 protein plasma levels after aneurysmal subarachnoid haemorrhage. Acta Neurochirurgica 1997;139: 1155e60. Wiesmann M, Wandinger KP, Missler U, Eckhoff D, Rothermundt M, Arolt V, et al. Elevated plasma levels of S-100b protein in schizophrenic patients. Biological Psychiatry 1999;45:1508e11.
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Increased serum S100B in never-medicated and medicated schizophrenic patients Xiang Yang Zhang a, b, c, *,1, Mei Hong Xiu b,1, Cai Song d, Da Chun Chen b, Gui Ying Wu c, Colin N. Haile c, Therese A. Kosten c, Thomas R. Kosten c, ** a
Institute of Psychology, Chinese Academy of Sciences, Beijing, PR China Center for Biological Psychiatry, Beijing Hui Long Guan Hospital, Beijing, PR China c Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, Texas, USA d Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 January 2010 Received in revised form 6 April 2010 Accepted 20 April 2010
S100B is a calcium-binding protein, which is produced primarily by glial cells. It modulates the proliferation and differentiation of neurons and glia by affecting protective and apoptotic mechanisms. Recently, several studies have shown increased serum S100B levels in patients with schizophrenia, suggesting that S100B might be relevant to the pathophysiology of schizophrenia. S100B levels were assessed using ELISA in the serum of 80 never-medicated early-stage and 82 medicated chronic schizophrenia patients and 97 healthy controls subjects. The psychopathology of schizophrenia was assessed by the Positive and Negative Syndrome Scale (PANSS). Our results showed significantly increased serum S100B levels in both never-medicated and medicated patients compared to normal controls (both p < 0.0001). S100B in never-medicated patients was also markedly increased, compared with medicated patients (p < 0.0001). S100B changes observed were irrespective of neuroleptic medication, gender, age, and smoking. Increased S100B levels in the early stage of schizophrenia suggest that glial cell activation or structural damage may be part of a neurodegenerative process in schizophrenia. The lower S100B levels in chronic than early-stage patients further suggest that antipsychotic treatment may reduce this neurodegeneration. Ó 2010 Elsevier Ltd. All rights reserved.
Keywords: Schizophrenia S100B Early psychosis Antipsychotic treatment Psychopathology
1. Introduction The S100B protein (S100B) is a calcium-binding protein, mainly produced and secreted by astrocytes that exert paracrine and autocrine effects on neurons and glia. It achieves this by regulating a variety of cellular mechanism such as proliferation, differentiation, cellular energy metabolism and cytoskeletal modification through mediating phosphorylation of key synaptic proteins (Donato, 2001; Sen and Belli, 2007). Interestingly, secreted glial S100B exerts either trophic or toxic effects depending on its concentration with nanomolecular concentrations being * Corresponding author at: VA Medical Center, Research Building 109, Room 130, 2002 Holcombe Boulevard, Houston, Texas, 77030, USA. Tel.: þ1 7137911414x5824; fax: þ1 713 794 7938. ** Corresponding author at: VA Medical Center, Research Building 110, Room 229, 2002 Holcombe Boulevard, Houston, Texas, 77030, USA. Tel.: þ1 7137947032; fax: þ1 713 794 7938. E-mail addresses: [email protected] (X.Y. Zhang), [email protected] (T.R. Kosten). 1 These two authors (Xiang Yang Zhang and Mei Hong Xiu) contributed equally to this study. 0022-3956/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpsychires.2010.04.023
neuroprotective whereas micromolecular concentrations promote apoptosis (Rothermundt et al., 2003, 2004a), thus is viewed as a marker of structural damage, or increased active synthesis and release (Steiner et al., 2006, 2008b; van Beveren et al., 2006). Although S100B has been regarded a marker of astroglial cellular integrity, yet S100B is also expressed in other neural cells such as oligodendrocytes (Steiner et al., 2006, 2008a) and is detected outside the central nervous system (CNS) (Steiner et al., 2007), such as in adipocytes (Steiner et al., 2010a,b). Most studies have shown that S100B is increased in cerebrospinal fluid (CSF) and serum of schizophrenic patients, especially during acute stages of the disease with persistently high S100B levels positively associated with negative or deficit symptoms (Rothermundt et al., 2001, 2004a,b; Sarandol et al., 2007; Holtkamp et al., 2008; Tan et al., 2010), with only a few exceptions (Schmitt et al., 2005). A recent histological study has also shown that cortical brain regions contained more S100B-immunopositive glia in the schizophrenia group relative to controls, particularly in dorsolateral prefrontal (DLPF) brain area (Steiner et al., 2008b). Furthermore, two most recent meta-analyses have shown consistently higher S100B in schizophrenia patients (Schroeter et al.,
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2009; Schroeter and Steiner, 2009). Antipsychotic medications alleviate-to an extent- schizophrenic symptoms. Thus, studies have attempted to link antipsychotic therapeutic action to effects on S100B with conflicting results. For example, patients receiving typical or atypical antipsychotic drugs in comparison to unmedicated patients showed higher levels of S100B (Schroeter et al., 2003), whereas others found no influence of medication (Sarandol et al., 2007). Still, some authors observed that treatment with antipsychotic drug treatment for several weeks normalized S100B levels (Rothermundt et al., 2001, 2004b). These studies suggest that S100B might be relevant in the pathophysiology of schizophrenia. One recent study showed increased S100B levels in first-episode and drug-naïve schizophrenic patients (Tan et al., 2010). However, no studies have compared S100B levels in drug-naïve and medicated schizophrenic patients. The present study therefore examined three issues: (1) Are serum S100B levels altered in never-medicated early-stage psychotic patients at the onset of psychosis compared to normal controls and to chronic medicated schizophrenic patients? (2) Is there a difference in the effects of typical and atypical antipsychotics on S100B levels? (3) Are S100B levels related to psychopathological symptoms in never-medicated and medicated schizophrenic patients?
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Normal controls (97; male/female ¼ 59/38) were recruited from the local community. None of them had a personal or family history of psychiatric disorder, and all were Han Chinese from the Beijing area. Table 1 summarizes the demographics for patients and normal controls. All patients and control subjects were in good physical health, and any subjects with major medical illnesses or drug and alcohol abuse/dependence were excluded. All subjects gave written informed consent, which was approved by the Institutional Review Board of Beijing HuiLongGuan hospital. 2.2. Serum S100B measurements Serum samples were collected between 07.00 and 09.00 h following an overnight fast. Serum S100B levels were measured in duplicate in all subjects by sandwich ELISA using a commercially available kit (R&D systems, Beijing, China). A full description of the assays has been given in our previous report (Qi et al., 2009). All samples were assayed by the same investigator, who was blind to the clinical situation. The sensitivity of the assay was 0.1 ng/ml. Inter- and intra-assay variation coefficients were 6% and 4%, respectively. 2.3. Psychopathological assessment in patients
2. Methods 2.1. Subjects We recruited 80 (male/female ¼ 42/38) never-medicated and early-stage patients meeting DSM-IV criteria for schizophrenia from consecutive admissions at the inpatient unit of Beijing HuiLongGuan hospital, a Beijing city-owned psychiatric hospital. All patients were reassessed and confirmed after 3-month follow-up. Their clinical subtypes were: paranoid, 41 (51.2%), undifferentiated, 31 (38.8%); disorganized 6 (7.5%); others 2 (2.5%). Eighty two chronic medicated schizophrenic patients (male/ female ¼ 57/25) were also introduced into the study at the same hospital. Both never-medicated and medicated patients were diagnosed by two independent and experienced psychiatrists and confirmed by the Structured Clinical Interview for DSM-IV (SCID). The chronic patients had a mean illness course of 26.6 8.7 years with 8.7 6.8 years of hospitalization. They were receiving stable doses of oral neuroleptics for at least 12 months including clozapine (n ¼ 31), risperidone (n ¼ 22), perphenazine (n ¼ 9), haloperidol (n ¼ 8), chlorpromazine (n ¼ 6), and sulpiride (n ¼ 6). Their clinical subtypes were: 36 paranoid (43.9%), 10 disorganized (12.2%), 4 undifferentiated (4.9%) and 32 residual types (39.0%).
Four psychiatrists, who were blind to the clinical status and treatment condition, assessed the patient’s psychopathology using the Positive and Negative Syndrome Scale (PANSS) on the day of the blood sampling. To ensure consistency and reliability of rating across the study, these four psychiatrists who had worked at least 5 years in clinical practice, were trained in using the PANSS before the start of the study. After training a correlation coefficient greater than 0.8 was maintained for interrater reliability on the PANSS total score at repeated assessments during the study. 2.4. Statistical analysis We compared the S100B levels in the never-medicated and medicated patient and control groups using a univariate analysis of covariance (ANCOVA) with gender, age and smoking as covariates. Post hoc comparisons between groups were made using the Bonferroni procedure. Furthermore, univariate analysis of variance (ANOVA) and ANCOVA were also used to compare between-group differences. Bonferroni corrections were applied to each test to adjust for multiple testing. Psychopathology on the PANSS was compared between the patient groups by one-way ANOVA and correlated with S100B levels within patient groups by calculating
Table 1 Demographic data in never medicated and early-stage, chronic schizophrenia patients and control groups.
Male/Female Age (yrs) Cigarette smoking Male Female Duration of Illness (yrs) PANSS total P subscore N subscore G subscore S100B (ng/ml)
Never-medicated (n ¼ 80)
Medicated patients (n ¼ 82)
Normal control (n ¼ 97)
p value
42/38 29.1 9.6 22 (28%) 19 (86%) 3 (14%) 2.1 1.9 83.4 18.9 25.6 6.2 18.4 7.2 39.7 11.5 0.541 0.214***, ###
57/25 50.9 7.0 50 (61%) 48 (96%) 2 (4%) 26.6 8.7 58.4 13.2 12.4 6.0 19.8 6.5 26.1 5.4 0.351 0.116###
59/38 37.9 9.0 33 (34%) 28 (85%) 5 (15%) NA NA NA NA NA 0.122 0.076
ns <0.001 <0.001
<0.001 <0.001 <0.001 ns <0.001 <0.001
Note: * indicates the comparison between never medicated and early-stage and medicated chronic patients. *** p < 0.001. # indicates the comparison between patients and normal controls. ###p < 0.001. Abbreviations: PANSS ¼ the Positive and Negative Syndrome Scale; P ¼ positive symptom; N ¼ negative symptom; G ¼ general psychopathology; S100B ¼ the S100B protein.
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Pearson correlation coefficients. Stepwise multiple regression analysis using S100B as dependent variable was performed to investigate the impact of age, gender, duration of illness, age of onset and psychopathological symptoms shown by PANSS and its subscales. Two-tailed significance values were used and significance levels were set at 0.05. 3. Results Table 1 shows the demographic data of the subjects included in the study. Never-medicated, medicated patients and control subjects significantly differed in age (p < 0.001) and smoking (p < 0.001), and duration of illness between never-medicated and medicated patients (p < 0.001). A possible influence of age on S100B was investigated calculating Pearson correlation coefficients between S100B and age in control subjects. Statistical analysis here revealed no influence of age on S100B in normal controls (r ¼ 0.11, ns). Gender distribution was not different between groups (X2 ¼ 4.93, df ¼ 2, p ¼ 0.09) (Table 1). To analyze gender as potential co-variable of the target parameter (S100B), univariate ANOVA was performed in the whole group, or when the normal controls and patients (never-medicated and medicated) were examined separately. There was no influence of gender on S100B levels (all p > 0.05). 3.1. Serum S100B levels Serum S100B levels were significantly different among nevermedicated patients, medicated patients and normal control groups when age was added as a covariate [F(2,256) ¼ 119.1, p < 0.0001]. Furthermore, when gender and smoking were added as additionally confounding covariate terms, the differences between the patients and controls remained significant [F(5,256) ¼ 154.6, p < 0.0001]. Post hoc comparisons using the Bonferroni procedure showed significantly increased S100B in never-medicated patients and medicated patients compared to normal controls (both p < 0.0001). Furthermore, significant increase in S100B was observed in never-medicated patients compare to medicated patients (p < 0.0001) (Table 1; Fig. 1). In addition, separate group comparisons of S100B among these three groups using ANCOVA with age, sex and smoking behavior as covariate terms still showed similar results (all p < 0.0001). 0.8
Furthermore, separate group comparisons of S100B within the patient sample using univariate ANOVA showed a highly significant difference in S100B between never-medicated and medicated patients [Fig. 1; F(1,160) ¼ 46.6, p < 0.0001]. When age, sex, duration of illness and smoking were added as potentially confounding covariate terms, the differences remained significant (p < 0.0001). In addition, correlation analysis did not reveal significant influence of age or duration of illness on S100B in never-medicated and medicated patients separately (all p > 0.05). 3.2. Psychopathology and S100B There were significant differences between the never-medicated and medicated patients on the PANSS total, positive and general psychopathology (all p < 0.001), but not negative scores (P > 0.05) (Table 1). Correlation analysis of data from all patients showed that S100B levels were not associated with any psychopathological parameters (all p > 0.05). Furthermore, separate correlation analysis showed that S100B levels were not associated with any psychopathological parameters within either the nevermedicated or medicated groups of patients (all p > 0.05). Stepwise multiple regression analysis including PANSS and its subscales, age, gender, duration of illness, age of onset and smoking and S100B levels (as dependent variable) in patient groups did not identify any variables as the influencing factors for S100B (p > 0.05). 3.3. Other confounding factors Other possible confounding factors in the differences in S100B levels included cigarette smoking, and antipsychotic agent type, current mean dose over one month before the start of the study, and duration of treatment. Cigarette smoking differed among groups (p < 0.001), with more chronic patients smoking (61%), than normal controls (34%) or early-stage patients (28%). As a whole, S100B levels did not differ between cigarette smokers and non-smokers, or when the normal controls and patients (never-medicated and medicated) were examined separately (all p > 0.05). Among the chronic patients S100B levels were not significantly affected by typical vs. atypical neuroleptics, dose or duration of antipsychotic treatment (all p > 0.05). Furthermore, no significant difference in S100B was noted between clozapine (n ¼ 31) risperidone (n ¼ 22) and typical antipsychotic (n ¼ 29) subgroups (all p > 0.05).
S100B (ng/ml)
4. Discussion
0.4
0
NC
CMP
DNP
Fig. 1. Serum S100B in drug-naïve patients (DNP) with schizophrenia (n ¼ 80), chronic medicated patients (CMP) with schizophrenia (n ¼ 82) and normal controls (NC) (n ¼ 97). The sample means are indicated by the black bars. S100B levels were significantly higher in both first episode patients and chronic patients than normal controls (both p < 0.001). S100B in first-episode patients was also markedly increased compared with chronic patients (p < 0.0001).
Our results show that S100B is significantly elevated in drugnaïve early-stage schizophrenic patients. These levels were also significantly greater compared to medicated chronic schizophrenic patients. Increased serum S100B levels in our early-stage drugnaïve schizophrenic patients are consistent with that seen in younger (Rothermundt et al., 2004a) or elderly chronic schizophrenic patients (Schmitt et al., 2005) as well as neuroleptic-free and medicated patients in an acute stage of disease (Gattaz et al., 2000; Rothermundt et al., 2001; Schroeter et al., 1999, 2003; Sarandol et al., 2007; Pedersen et al., 2008).In contrast, Gattaz et al. and Schroeter et al. failed to find any difference in serum levels of S100B in schizophrenic patients (Gattaz et al., 2000; Schroeter et al., 2003). However, differences in measurement techniques, testing material (CSF vs. plasma vs. serum), exposure to neuroleptic treatment (naive vs. medicated or drug withdrawal vs. medicated), sampling of patients in different stages of disease progression (acute vs. chronic or active phase vs. remission), different duration of illness, different ethnic origin, and duration of sample storage, may be responsible for these conflicting results.
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The source of circulating S100B remains unclear. Although S100B is predominantly expressed in astrocytes, it is also present in other brain cells such as oligodendrocytes, microglial or even neuronal cells (Steiner et al., 2007). There is evidence that oligodendrocytes independently produce S100B (Steiner et al., 2008a,b). Also, there is a large body of evidence for an affection of oligodendrocytes in schizophrenia, e.g. post-mortem studies (Uranova et al., 2004, 2007; Schmitt et al., 2009; Farkas et al., 2010), or microarray studies (Tkachev et al., 2003). Furthermore, no study has tested whether astrocytes produce more S100B than oligodendrocytes in human brain, and what S100B concentrations are in the brain in schizophrenia. Also, extracerebral sources of S100B have been described such as in adipose tissue, lymphocytes, melanocytes, the myocardium, vascular endothelial/smooth muscle cells, satellite cells of dorsal root ganglia, and Schwann cells of peripheral nervous system (Donato, 2001; Steiner et al., 2007, 2008a, 2010a,b). However, blood levels of S100B are unlikely to result from peripheral sources, since it is found predominantly in the cytosol of brain glial cells and may leak from structurally damaged glial cells into the CSF and then into the blood, particularly through the permeable blood brain barrier of schizophrenia (Steiner et al., 2006). In healthy controls S100B serum measures reliably reflect S100B concentrations in the CSF (Nygaard et al., 1997). Both S100B CSF and blood levels correlate with the clinical severity of damage to the CNS (Lamers et al., 1995; Wiesmann et al., 1997) and neurological diseases that increase CSF S100B concurrently increase peripheral blood S100B (van Beveren et al., 2006). Elevated S100B serum levels are associated with increased myo-inositol concentrations in schizophrenics’ brains (Rothermundt et al., 2007). It is presumed that elevated serum S100B in schizophrenic patients reflects central damage because physical myelin integrity is restored in patients that respond to antipsychotic medications (Garver et al., 2008). On the other hand, a recent histological study has shown that cortical brain regions contained more S100B-immunopositive glia in the schizophrenia group relative to controls. Moreover, the white matter of patients with paranoid schizophrenia contained more (mainly oligodendrocytic) S100B-positive glia as compared to residual schizophrenia. Their results suggest that astro-/oligodendroglial activation may result in increased cellular S100B in paranoid schizophrenia. On the contrary, residual schizophrenia may be caused by white matter oligodendroglial damage or dysfunction, associated with a release of S100B into body fluids (Steiner et al., 2008b). Taken together, increased S100B in drug-naïve early-stage schizophrenic patients in our present study indicates that structurally damaged or activated glial cells associated with release of S100B may be part of a neurodegenerative process during the early stage of schizophrenia, suggesting a role in the pathogenesis of illness. Furthermore, we found lower S100B levels in chronic schizophrenic patients treated for several years with antipsychotics compared to never-medicated early-stage patients. This suggests another therapeutic mechanism of antipsychotic medications. Two previous studies found increased S100B serum levels during the initial phase of schizophrenic psychoses followed by normalization of these levels during the chronic stage of illness (Rothermundt et al., 2001; Ling et al., 2007). This effect however appears to be selective for patients with predominantly positive symptoms because elevated levels of circulating S100B persists in those patients with negative symptomology even after antipsychotic treatment (Rothermundt et al., 2001, 2004a,b). In contrast, other reports show low S100B plasma levels in schizophrenic outpatients, mostly treated with clozapine (Gattaz et al., 2000), and in unmedicated schizophrenic patients compared to patients receiving antipsychotic medication for about 3 weeks (Schroeter et al., 2003). The authors suggest that antipsychotics may initially increase S100B during the early phase of treatment, and then after
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a month or more antipsychotics may decrease S100B in patients with relatively few negative symptoms (Schroeter et al., 2003). However, in our present study, S100B levels of clozapine-treated patients were not different from those patients on risperidone and typical antipsychotic medication treatment. Although we did not assess the possibility if S100B levels are altered in earlystage schizophrenic patients in response to antipsychotic medication studies directly assessing this possibility are warranted to clarify the temporal aspects of S100B in the pathogenesis of this disease. Several points should be noted here. First, the measurement of S100B levels resulted in about 2e4 times higher levels in controls and schizophrenia subjects in our current study than in most previous studies (Schroeter et al., 2009). This difference in S100B levels in subjects is most likely due to the assay employed, especially the differences in the sensitivity/specificity. Another possible explanation is that there are significant differences in S100B genotype frequencies observed in different populations. Recent studies have shown an ethnicity-based variability in the allelic frequency and genotype inheritance patterns for S100B (Liu et al., 2005), suggesting that polymorphisms within S100B genes may be responsible for the ethnic-based differences in S100B levels. Unfortunately, there is no direct comparison study yet on the S100B genotype between Chinese and Caucasians. Second, we examined our patients only once in a cross-sectional rather than longitudinal comparison between naive and long term medicated states. Third, serum S100B differences may be related to severe stress (Scaccianoce et al., 2004), such as that experienced by our early-stage unmedicated psychotic patients. Further studies will need to evaluate the role of stress on S100B perhaps through measuring hormone levels related to the hypothalamicepituitaryeadrenal (HPA) axis. Fourth, most recently, it has been shown that S100B is related to body-mass-index (BMI) and insulin resistance (Steiner et al., 2010a,b), which is also relevant for patients suffering from schizophrenia, due to the increased prevalence of metabolic syndrome, and weight gain and obesity in schizophrenia on antipsychotic pharmacotherapy (Correll and Malhotra, 2004). Unfortunately, we did not control for BMI in the present study. Hence, whether the increased S100B in schizophrenia in our present study is caused by increased weight gain and metabolic syndrome cannot be ruled out, which deserves further investigation. In conclusion, serum S100B is significantly elevated in both never-medicated early-stage and medicated patients with chronic schizophrenia, which supports activation or damage of glial cells, especially astrocytes as a contributor to the pathogenesis of schizophrenia (Lamers et al., 1995). Antipsychotic treatment probably accounts for the lower S100B levels in medicated chronic schizophrenic patients than in unmedicated early-stage patients. Thus, these results support the notion that schizophrenic patients appear to be suffering ongoing activation or structural damage to glial cells, particularly to astrocytes and antipsychotics may attenuate this process contributing to therapeutic efficacy (Schafer and Heizmann, 1996; Wiesmann et al., 1999). Role of the funding source This study was funded by the Beijing Municipal Natural Science Foundation (ID: 7072035), the Stanley Medical Research Institute (03T-459 and 05T-726), and the Department of Veterans Affairs, VISN 16, Mental Illness Research, Education and Clinical Center (MIRECC), United States National Institute of Health K05-DA0454, P50-DA18827 and U01-MH79639. These sources had no further role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.
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Contributors Xiang Yang Zhang and Mei Hong Xiu were responsible for study design, statistical analysis, and manuscript preparation. Mei Hong Xiu and Da Chun Chen were responsible for recruiting the patients, performing the clinical rating and collecting the samples. Cai Song, Gui Ying Wu, Colin Haile, and Therese Kosten were involved in evolving the ideas and editing the manuscript. Thomas Kosten was involved in writing the protocol, cowrote the paper and was responsible for providing the funding for the study. All authors have contributed to and have approved the final manuscript. Conflict of interest The authors have no conflicts to disclose. References Correll CU, Malhotra AK. Pharmacogenetics of antipsychotic-induced weight gain. Psychopharmacology (Berl) 2004;174(4):477e89. Donato R. S100: a multigenic family of calcium-modulated proteins of the EFhand type with intracellular and extracellular functional roles. The International Journal of Biochemistry & Cell Biology 2001;33:637e68. Farkas N, Lendeckel U, Dobrowolny H, Funke S, Steiner J, Keilhoff G, et al. Reduced density of ADAM 12-immunoreactive oligodendrocytes in the anterior cingulate white matter of patients with schizophrenia. World Journal of Biological Psychiatry 2010;11(3):193e203. Garver DL, Holcomb JA, Christensen JD. Compromised myelin integrity during psychosis with repair during remission in drug-responding schizophrenia. International Journal of Neuropsychopharmacology 2008;11:49e61. Gattaz WF, Lara DR, Elkis H, Portela LV, Gonçalves CA, Tort AB, et al. Decreased S100beta protein in schizophrenia: preliminary evidence. Schizophrenia Research 2000;43:91e5. Holtkamp K, Buhren K, Ponath G, von Eiff C, Herpertz-Dahlmann B, Hebebrand J, et al. Serum levels of S100B are decreased in chronic starvation and normalize with weight gain. Journal of Neural Transmission 2008;115:937e40. Lamers KJ, van Engelen BG, Gabreels FJ, Hommes OR, Borm GF, Wevers RA. Cerebrospinal neuron-specific enolase, S-100 and myelin basic protein in neurological disorders. Acta Neurologica Scandinavica 1995;92:247e51. Ling SH, Tang YL, Jiang F, Wiste A, Guo SS, Weng YZ, et al. Plasma S-100B protein in Chinese patients with schizophrenia: comparison with healthy controls and effect of antipsychotics treatment. Journal of Psychiatric Research 2007;41:36e42. Liu J, Shi Y, Tang J, Guo T, Li X, Yang Y, et al. SNPs and haplotypes in the S100B gene reveal association with schizophrenia. Biochemical and Biophysical Research Communications 2005;328(1):335e41. Nygaard O, Langbakk B, Romner B. Age- and sex-related changes of S-100 protein concentrations in cerebrospinal fluid and serum in patients with no previous history of neurological disorder. Clinical Chemistry 1997;43:541e3. Pedersen A, Diedrich M, Kaestner F, Koelkebeck K, Ohrmann P, Ponath G, et al. Memory impairment correlates with increased S100B serum concentrations in patients with chronic schizophrenia. Progress in Neuro-Psychopharmacology and Biological Psychiatry 2008;32:1789e92. Qi LY, Xiu MH, Chen da C, Wang F, Kosten TA, Kosten TR, et al. Increased serum S100B levels in chronic schizophrenic patients on long-term clozapine or typical antipsychotics. Neuroscience Letters 2009;462(2):113e7. Rothermundt M, Missler U, Arolt V, Peters M, Leadbeater J, Wiesmann M, et al. Increased S100B blood levels in unmedicated and treated schizophrenic patients are correlated with negative symptomatology. Molecular Psychiatry 2001;6:445e9. Rothermundt M, Peters M, Prehn JH, Arolt V. S100B in brain damage and neurodegeneration. Microscopy Research and Technique 2003;60:614e32. Rothermundt M, Ponath G, Glaser T, Hetzel G, Arolt V. S100B serum levels and long term improvement of negative symptoms in patients with schizophrenia. Neuropsychopharmacology 2004a;29:1004e11. Rothermundt M, Falkai P, Ponath G, Abel S, Bürkle H, Diedrich M, et al. Glial cell dysfunction in schizophrenia indicated by increased S100B in the CSF. Molecular Psychiatry 2004b;9:897e9. Rothermundt M, Ohrmann P, Abel S, Siegmund A, Pedersen A, Ponath G, et al. Glial cell activation in a subgroup of patients with schizophrenia indicated by
increased S100B serum concentrations and elevated myo-inositol. Progress in Neuro-Psychopharmacology and Biological Psychiatry 2007;30:361e4. Sarandol A, Kirli S, Akkaya C, Altin A, Demirci M, Sarandol E. Oxidative/antioxidative systems and their relation with serum S100 B levels in patients with schizophrenia: effects of short term antipsychotic treatment. Progress in NeuroPsychopharmacology and Biological Psychiatry 2007;31:1164e9. Scaccianoce S, Del Bianco P, Pannitteri G, Passarelli F. Relationship between stress and circulating levels of S100B protein. Brain Research 2004;1004:208e11. Schafer BW, Heizmann CW. The S100 family of EF-hand calcium-binding proteins: functions and pathology. Trends in Biochemical Sciences 1996;21:134e40. Schmitt A, Bertsch T, Henning U, Tost H, Klimke A, Henn FA, et al. Increased serum S100B in elderly, chronic schizophrenic patients: negative correlation with deficit symptoms. Schizophrenia Research 2005;80:305e13. Schmitt A, Steyskal C, Bernstein HG, Schneider-Axmann T, Parlapani E, Schaeffer EL, et al. Stereologic investigation of the posterior part of the hippocampus in schizophrenia. Acta Neuropathologica 2009;117:395e407. Schroeter ML, Mertsch K, Giese H, Müller S, Sporbert A, Hickel B, et al. Astrocytes enhance radical defence in capillary endothelial cells constituting the bloodebrain barrier. FEBS Letters 1999;49:241e4. Schroeter ML, Abdul-Khaliq H, Frühauf S, Höhne R, Schick G, Diefenbacher A, et al. Serum S100B is increased during early treatment with antipsychotics and in deficit schizophrenia. Schizophrenia Research 2003;(62):231e6. Schroeter ML, Abdul-Khaliq H, Krebs M, Diefenbacher A, Blasig IE. Neuron-specific enolase is unaltered whereas S100B is elevated in serum of patients with schizophrenia e original research and meta-analysis. Psychiatry Research 2009;167:66e72. Schroeter ML, Steiner J. Elevated serum levels of the glial marker protein S100B are not specific for schizophrenia or mood disorders. Molecular Psychiatry 2009;14:235e7. Sen J, Belli A. S100B in neuropathologic states: the CRP of the brain? Journal of Neuroscience Research 2007;85:1373e80. Steiner J, Bielau H, Bernstein HG, Bogerts B, Wunderlich MT. Increased cerebrospinal fluid and serum levels of S100B in first-onset schizophrenia are not related to a degenerative release of glial fibrillar acidic protein, myelin basic protein and neurone-specific enolase from glia or neurones. The Journal of Neurology, Neurosurgery, and Psychiatry 2006;77:1284e7. Steiner J, Bernstein HG, Bielau H, Berndt A, Brisch R, Mawrin C, et al. Evidence for a wide extra-astrocytic distribution of S100B in human brain. BMC Neuroscience 2007;8:2. Steiner J, Bernstein HG, Bogerts B, Gos T, Richter-Landsberg C, Wunderlich MT, et al. S100B is expressed in, and released from, OLN-93 oligodendrocytes: Influence of serum and glucose deprivation. Neuroscience 2008a;154:496e503. Steiner J, Bernstein HG, Bielau H, Farkas N, Winter J, Dobrowolny H, et al. Bogerts, B. S100B-immunopositive glia is elevated in paranoid as compared to residual schizophrenia: a morphometric study. Journal of Psychiatric Research 2008b;42:868e76. Steiner J, Schiltz K, Walter M, Wunderlich MT, Keilhoff G, Brisch R, et al. S100B serum levels are closely correlated with body mass index: an important caveat in neuropsychiatric research. Psychoneuroendocrinology 2010a;35:321e4. Steiner J, Walter M, Guest P, Myint AM, Schiltz K, Panteli B, et al. Elevated S100B levels in schizophrenia are associated with insulin resistance. Molecular Psychiatry 2010b;15(1):3e4. Tan Y, Luo X, Yang F, Zhang W, Wang Z, Zou Y, et al. Elevated serum S100B protein in first-episode drug-naïve Chinese patients with schizophrenia. Schizophrenia Research; 2010 Feb 16 [Epub ahead of print]. Tkachev D, Mimmack ML, Ryan MM, Wayland M, Freeman T, Jones PB, et al. Oligodendrocyte dysfunction in schizophrenia and bipolar disorder. Lancet 2003;362(9386):798e805. Uranova NA, Vostrikov VM, Orlovskaya DD, Rachmanova VI. Oligodendroglial density in the prefrontal cortex in schizophrenia and mood disorders: a study from the Stanley Neuropathology Consortium. Schizophrenia Research 2004;67:269e75. Uranova NA, Vostrikov VM, Vikhreva OV, Zimina IS, Kolomeets NS, Orlovskaya DD. The role of oligodendrocyte pathology in schizophrenia. International Journal of Neuropsychopharmacology 2007;10(4):537e45. van Beveren NJ, van der Spelt JJ, de Haan L, Fekkes D. Schizophrenia-associated neural growth factors in peripheral blood. A review. European Neuropsychopharmacology 2006;16:469e80. Wiesmann M, Missler U, Hagenstrom H, Gottmann D. S-100 protein plasma levels after aneurysmal subarachnoid haemorrhage. Acta Neurochirurgica 1997;139: 1155e60. Wiesmann M, Wandinger KP, Missler U, Eckhoff D, Rothermundt M, Arolt V, et al. Elevated plasma levels of S-100b protein in schizophrenic patients. Biological Psychiatry 1999;45:1508e11.