Neuroreceptor Inhibition by Clozapine Triggers Mitohormesis and Metabolic Reprogramming in Human Blood Cells.

The antipsychotic drug clozapine demonstrates superior efficacy in treatment-resistant schizophrenia, but its intracellular mode of action is not completely understood. Here, we analysed the effects of clozapine (2.5-20 µM) on metabolic fluxes, cell respiration, and intracellular ATP in human HL60 cells. Some results were confirmed in leukocytes of clozapine-treated patients. Neuroreceptor inhibition under clozapine reduced Akt activation with decreased glucose uptake, thereby inducing ER stress and the unfolded protein response (UPR). Metabolic profiling by liquid-chromatography/mass-spectrometry revealed downregulation of glycolysis and the pentose phosphate pathway, thereby saving glucose to keep the electron transport chain working. Mitochondrial respiration was dampened by upregulation of the F0F1-ATPase inhibitory factor 1 (IF1) leading to 30-40% lower oxygen consumption in HL60 cells. Blocking IF1 expression by cotreatment with epigallocatechin-3-gallate (EGCG) increased apoptosis of HL60 cells. Upregulation of the mitochondrial citrate carrier shifted excess citrate to the cytosol for use in lipogenesis and for storage as triacylglycerol in lipid droplets (LDs). Accordingly, clozapine-treated HL60 cells and leukocytes from clozapine-treated patients contain more LDs than untreated cells. Since mitochondrial disturbances are described in the pathophysiology of schizophrenia, clozapine-induced mitohormesis is an excellent way to escape energy deficits and improve cell survival.

Sex-Specific Effects of Long-Term Antipsychotic Drug Treatment on Adipocyte Tissue and the Crosstalk to Liver and Brain in Rats.

Antipsychotic drug (APD) medication can lead to metabolic dysfunctions and weight gain, which together increase morbidity and mortality. Metabolically active visceral adipose tissue (VAT) in particular plays a crucial role in the etiopathology of these metabolic dysregulations. Here, we studied the effect of 12 weeks of drug medication by daily oral feeding of clozapine and haloperidol on the perirenal fat tissue as part of VAT of male and female Sprague Dawley rats in the context of complex former investigations on brain, liver, and blood. Adipocyte area values were determined, as well as triglycerides, non-esterified fatty acids (NEFAs), glucose, glycogen, lactate, malondialdehyde equivalents, ferric iron and protein levels of Perilipin-A, hormone-sensitive-lipase (HSL), hepcidin, glucose transporter-4 (Glut-4) and insulin receptor-ß (IR-ß). We found increased adipocyte mass in males, with slightly higher adipocyte area values in both males and females under clozapine treatment. Triglycerides, NEFAs, glucose and oxidative stress in the medicated groups were unchanged or slightly decreased. In contrast to controls and haloperidol-medicated rats, perirenal adipocyte mass and serum leptin levels were not correlated under clozapine. Protein expressions of perilipin-A, Glut-4 and HSL were decreased under clozapine treatment. IR-ß expression changed sex-specifically in the clozapine-medicated groups associated with higher hepcidin levels in the perirenal adipose tissue of clozapine-treated females. Taken together, clozapine and haloperidol had a smaller effect than expected on perirenal adipose tissue. The perirenal adipose tissue shows only weak changes in lipid and glucose metabolism. The main changes can be seen in the proteins examined, and probably in their effect on liver metabolism.

Why Is Iron Deficiency/Anemia Linked to Alzheimer's Disease and Its Comorbidities, and How Is It Prevented?

Impaired iron metabolism has been increasingly observed in many diseases, but a deeper, mechanistic understanding of the cellular impact of altered iron metabolism is still lacking. In addition, deficits in neuronal energy metabolism due to reduced glucose import were described for Alzheimer's disease (AD) and its comorbidities like obesity, depression, cardiovascular disease, and type 2 diabetes mellitus. The aim of this review is to present the molecular link between both observations. Insufficient cellular glucose uptake triggers increased ferritin expression, leading to depletion of the cellular free iron pool and stabilization of the hypoxia-induced factor (HIF) 1α. This transcription factor induces the expression of the glucose transporters (Glut) 1 and 3 and shifts the cellular metabolism towards glycolysis. If this first line of defense is not adequate for sufficient glucose supply, further reduction of the intracellular iron pool affects the enzymes of the mitochondrial electron transport chain and activates the AMP-activated kinase (AMPK). This enzyme triggers the translocation of Glut4 to the plasma membrane as well as the autophagic recycling of cell components in order to mobilize energy resources. Moreover, AMPK activates the autophagic process of ferritinophagy, which provides free iron urgently needed as a cofactor for the synthesis of heme- and iron-sulfur proteins. Excessive activation of this pathway ends in ferroptosis, a special iron-dependent form of cell death, while hampered AMPK activation steadily reduces the iron pools, leading to hypoferremia with iron sequestration in the spleen and liver. Long-lasting iron depletion affects erythropoiesis and results in anemia of chronic disease, a common condition in patients with AD and its comorbidities. Instead of iron supplementation, drugs, diet, or phytochemicals that improve energy supply and cellular glucose uptake should be administered to counteract hypoferremia and anemia of chronic disease.

Sex-dependent effects of long-term clozapine or haloperidol medication on red blood cells and liver iron metabolism in Sprague Dawley rats as a model of metabolic syndrome.

BACKGROUND: Patients with liver diseases often have some form of anemia. Hematological dyscrasias are known side effects of antipsychotic drug medication and the occurrence of agranulocytosis under clozapine is well described. However, the sex-dependent impact of clozapine and haloperidol on erythrocytes and symptoms like anemia, and its association with hepatic iron metabolism has not yet been completely clarified. Therefore, in the present study, we investigated the effect of both antipsychotic drugs on blood parameters and iron metabolism in the liver of male and female Sprague Dawley rats. METHODS: After puberty, rats were treated orally with haloperidol or clozapine for 12 weeks. Blood count parameters, serum ferritin, and liver transferrin bound iron were determined by automated counter. Hemosiderin (Fe3+) was detected in liver sections by Perl's Prussian blue staining. Liver hemoxygenase (HO-1), 5'aminolevulinate synthase (ALAS1), hepcidin, heme-regulated inhibitor (HRI), cytochrome P4501A1 (CYP1A1) and 1A2 (CYP1A2) were determined by Western blotting. RESULTS: We found anemia with decreased erythrocyte counts, associated with lower hemoglobin and hematocrit, in females with haloperidol treatment. Males with clozapine medication showed reduced hemoglobin and increased red cell distribution width (RDW) without changes in erythrocyte numbers. High levels of hepatic hemosiderin were found in the female clozapine and haloperidol medicated groups. Liver HRI was significantly elevated in male clozapine medicated rats. CYP1A2 was significantly reduced in clozapine medicated females. CONCLUSIONS: The characteristics of anemia under haloperidol and clozapine medication depend on the administered antipsychotic drug and on sex. We suggest that anemia in rats under antipsychotic drug medication is a sign of an underlying liver injury induced by the drugs. Changing hepatic iron metabolism under clozapine and haloperidol may help to reduce these effects of liver diseases.

Sex-dependent alterations of dopamine receptor and glucose transporter density in rat hypothalamus under long-term clozapine and haloperidol medication.

OBJECTIVE: Sex-dependent disturbances of peripheral glucose metabolism are known complications of antipsychotic drug treatment. The influence of long-term clozapine and haloperidol medication on hypothalamus, maintaining aspects of internal body homeostasis, has not yet been completely clarified. METHODS: After puberty, male and female Sprague Dawley rats were fed orally with ground pellets containing haloperidol (1 mg/kgBW/day) or clozapine (20 mg/kgBW/day) for 12 weeks. The hypothalamic protein expression of dopamine receptors D2R and D4R, melanocortin receptor MC4R, and glucose transporters Glut1 and Glut3 was examined. Glucose, glycogen, lactate, and pyruvate levels were determined, also malondialdehyde equivalents as markers of oxidative stress. RESULTS: D2R expression was increased in the male haloperidol and clozapine group but decreased in females medicated with clozapine. D4R expression was upregulated under clozapine medication. While females showed increased Glut1, Glut3 was elevated in both male and female clozapine-medicated animals. We found no changes of hypothalamic malondialdehyde, glycogen, and MC4R. Hypothalamic lactate was elevated in the female clozapine group. CONCLUSION: Clozapine sex-dependently affects the expression of D2R, Glut1, and Glut3. The upregulation of the glucose transporters indicates glucose deprivation in the endothelial cells and consequently in astrocytes and neurons. Increased hypothalamic lactate in females under clozapine points to enhanced glycolysis with a higher glucose demand to produce the required energy. Haloperidol did not change the expression of the glucose transporters and upregulated D2R only in males.

Dysregulation of a specific immune-related network of genes biologically defines a subset of schizophrenia.

Currently, the clinical diagnosis of schizophrenia relies solely on self-reporting and clinical interview, and likely comprises heterogeneous biological subsets. Such subsets may be defined by an underlying biology leading to solid biomarkers. A transgenic rat model modestly overexpressing the full-length, non-mutant Disrupted-in-Schizophrenia 1 (DISC1) protein (tgDISC1 rat) was generated that defines such a subset, inspired by our previous identification of insoluble DISC1 protein in post mortem brains from patients with chronic mental illness. Besides specific phenotypes such as DISC1 protein pathology, abnormal dopamine homeostasis, and changes in neuroanatomy and behavior, this animal model also shows subtle disturbances in overarching signaling pathways relevant for schizophrenia. In a reverse-translational approach, assuming that both the animal model and a patient subset share common disturbed signaling pathways, we identified differentially expressed transcripts from peripheral blood mononuclear cells of tgDISC1 rats that revealed an interconnected set of dysregulated genes, led by decreased expression of regulator of G-protein signaling 1 (RGS1), chemokine (C-C) ligand 4 (CCL4), and other immune-related transcripts enriched in T-cell and macrophage signaling and converging in one module after weighted gene correlation network analysis. Testing expression of this gene network in two independent cohorts of patients with schizophrenia versus healthy controls (n = 16/50 and n = 54/45) demonstrated similar expression changes. The two top markers RGS1 and CCL4 defined a subset of 27% of patients with 97% specificity. Thus, analogous aberrant signaling pathways can be identified by a blood test in an animal model and a corresponding schizophrenia patient subset, suggesting that in this animal model tailored pharmacotherapies for this patient subset could be achieved.

Genetic susceptibility for air pollution-induced airway inflammation in the SALIA study.

BACKGROUND: Long-term air pollution exposure has been associated with chronic inflammation providing a link to the development of chronic health effects. Furthermore, there is evidence that pathways activated by endoplasmatic reticulum (ER) stress induce airway inflammation and thereby play an important role in the pathogenesis of inflammatory diseases. OBJECTIVE: We investigated the role of genetic variation of the ER stress pathway on air pollution-induced inflammation. METHODS: We used the follow-up examination of the German SALIA study (N=402, age 68-79 years). Biomarkers of inflammation were determined in induced sputum. We calculated biomarker-specific weighted genetic risk scores (GRS) out of eight ER stress related single nucleotide polymorphisms and tested their interaction with PM2.5, PM2.5 absorbance, PM10 and NO2 exposure on inflammation by adjusted linear regression. RESULTS: Genetic variation of the ER stress pathway was associated with higher concentration of inflammation-related biomarkers (levels of leukotriene (LT)B4, tumor necrosis factor-α (TNF-α), the total number of cells and nitric oxide (NO) derivatives). Furthermore, we observed a significant interaction between air pollution exposure and the ER stress risk score on the concentration of inflammation-related biomarkers. The strongest gene-environment interaction was found for LTB4 (PM2.5: p-value=0.002, PM2.5 absorbance: p-value=0.002, PM10: p-value=0.001 and NO2: p-value=0.004). Women with a high GRS had a 38% (95%-CI: 16-64%) higher LTB4 level for an increase of 2.06µg/m³(IQR) in PM2.5 (no associations in women with a low GRS). CONCLUSION: These results indicate that genetic variation in the ER stress pathway might play a role in air pollution induced inflammation in the lung.

Estrogen receptor beta polymorphisms and cognitive performance in women: associations and modifications by genetic and environmental influences.

Genetic and environmental risk factors contribute to the pathogenesis of Alzheimer's dementia. Besides known genetic risk factors like the apolipoprotein (APO) Eε4 allele, single nuclear polymorphisms (SNPs) of the estrogen receptors (ESRs) are candidate genetic risk factors, while air pollution represents an environmental risk factor for dementia. Effects of these risk factors and their interaction were investigated in the SALIA cohort of 834 non-demented elderly women. Cognitive function was assessed by the CERAD-plus test battery. Air pollution was estimated by land use regression (LUR) models. Genotyping was carried out for nine ESR1 and ESR2 SNPs and two ApoE SNPs. Carriers of minor ESR2 alleles showed significantly reduced cognitive performance in the CERAD total score with most pronounced deficits in semantic memory (rs1256062, rs10144225, and rs2274705) and executive function (rs1256062). The minor allele effects of ESR2 were stronger in carriers of APOEε4 for the cognitive domain 'executive function' (p value of interaction 0.023 for rs1256062). The investigated ESR1 SNPs were not associated with cognition. Furthermore, we found a significant gene-environment interaction between the ESR2 SNP rs1256062 and air pollution on cognition. Carriers of two major alleles of rs1256062 were more susceptible for an air pollution-induced decrease in performance of 'figure copying' than carriers of minor alleles (p value of interaction, e.g., 0.031 for PM2.5). In conclusion, ESR2 but not ESR1 minor alleles were associated with lower cognitive performance in elderly women with an indication of a gene-gene interaction with APOEε4. We also found indications for gene-environment interactions of ESR2 with traffic-related air pollution exposure on cognitive performance.

Association of air pollution with cognitive functions and its modification by APOE gene variants in elderly women.

BACKGROUND: Epidemiological studies have shown effects of long-term exposure to air pollution on cardiovascular and respiratory health. However, studies investigating the effects of air pollution on cognition and brain function are limited. We investigated if neurocognitive functions are associated with air pollution exposure and whether apolipoprotein E (ApoE) alleles modify the association of air pollution exposure with cognition. METHODS: We investigated 789 women from the SALIA cohort during the 22-year follow-up examination (2008-2009). Exposure to particulate matter (PM) size fractions and nitrogen oxides (NOx) were assigned to home addresses. Traffic indicators were used to assess residential proximity to high traffic load. Level of cognitive performance was assessed using the CERAD-Plus test. Air pollution effects on cognitive functioning were estimated cross-sectionally using adjusted linear regression models. RESULTS: Air pollution was negatively associated with cognitive function and cognitive performance in the subtests for semantic memory and visuo-construction. Significant associations could be observed for figure copying with an interquartile range increase of NO2 (ß=-0.28 (95%CI:-0.44;-0.12)), NOx (ß=-0.25 (95%CI:-0.40;-0.09)), PM10 (ß=-0.14 (95%CI:-0.26;-0.02)) and PM2.5 (ß=-0.19 (95%CI:-0.36;-0.02)). The association with traffic load was significant in carriers of one or two ApoE ɛ4 risk alleles. CONCLUSION: In this study of elderly women, markers of air pollution were associated with cognitive impairment in the visuospatial domain. The association of traffic exposure is significant in participants carrying the ApoE ε4 risk allele.

Peripheral DISC1 protein levels as a trait marker for schizophrenia and modulating effects of nicotine.

The Disrupted-in-Schizophrenia 1 (DISC1) protein plays a key role in behavioral control and vulnerability for mental illnesses, including schizophrenia. In this study we asked whether peripheral DISC1 protein levels in lymphocytes of patients diagnosed with schizophrenia can serve as a trait marker for the disease. Since a prominent comorbidity of schizophrenia patients is nicotine abuse or addiction, we also examined modulation of lymphocyte DISC1 protein levels in smokers, as well as the relationship between nicotine and DISC1 solubility status. We show decreased DISC1 levels in patients diagnosed with schizophrenia independent of smoking, indicating its potential use as a trait marker of this disease. In addition, lymphocytic DISC1 protein levels were decreased in smoking, mentally healthy individuals but not to the degree of overriding the trait level. Since DISC1 protein has been reported to exist in different solubility states in the brain, we also investigated DISC1 protein solubility in brains of rats treated with nicotine. Sub-chronic treatment with progressively increasing doses of nicotine from 0.25mg/kg to 1mg/kg for 15 days led to a decrease of insoluble DISC1 in the medial prefrontal cortex. Our results demonstrate that DISC1 protein levels in human lymphocytes are correlated with the diagnosis of schizophrenia independent of smoking and thus present a potential biomarker. Reduced DISC1 protein levels in lymphocytes of healthy individuals exposed to nicotine suggest that peripheral DISC1 could have potential for monitoring the effects of psychoactive substances.

Comment on "Impaired respiratory and body temperature control upon acute serotonergic neuron inhibition".

Ray et al. (Reports, 29 July 2011, p. 637) assume that clozapine-N4-oxide (CNO) represents a "biologically inert synthetic ligand" that selectively activates the M4 muscarinic receptor-based DREADD (designer receptor exclusively activated by a designer drug). In contrast, due to the redox cycling of CNO with clozapine and to their cell membrane permeability, CNO is biologically active and its conversion products are capable of undermining DREADD effects.

Clozapine mobilizes CD34+ hematopoietic stem and progenitor cells and increases plasma concentration of interleukin 6 in patients with schizophrenia.

The blood of 8 European patients with schizophrenia without manifest comorbidity was studied whether the classical atypical antipsychotic drug clozapine altered the amount of circulating CD34(+) hematopoietic cells. As assessed by flow cytometry, the number of CD34(+) cells increased by 433% (from 1.49 ± 1.07 × 10(6)/L, mean ± SD pretreatment, to a peak of 6.45 ± 3.47 × 10(6)/L) following first-time therapy with clozapine for 12 weeks. The increase of CD34(+) cell, neutrophil, and leukocyte counts was statistically significant (P = 0.012). A transversal investigation of 23 long-term patients and 58 controls showed elevated neutrophil counts in the clozapine-monotreated group, whereas CD34(+) cell numbers were unaltered. A transversal investigation of 12 clozapine-monotreated long-term patients and 10 controls revealed a 1.3-fold elevation of plasma interleukin 6 levels in patients on clozapine (P = 0.017). In conclusion, clozapine treatment results in an initial mobilization of CD34(+) stem and progenitor cells into the peripheral blood and in a slight long-term elevation of interleukin 6.

Clozapine therapy raises serum concentrations of high sensitive C-reactive protein in schizophrenic patients.

Eight schizophrenic inpatients without manifest comorbidity were longitudinally studied. The aim was to find whether clozapine, the prototype of atypical antipsychotic drugs, altered their serum concentrations of high sensitive C-reactive protein (hsCRP), an inflammatory marker of high clinical importance. Following first-time therapy with clozapine, predominantly as the sole antipsychotic for 8 weeks, hsCRP profiles increased subclinically by 600%. This rise, and the Spearman correlation between hsCRP values and corresponding leukocyte counts, was statistically significant. A one-time cross-section investigation of 25 long-term clozapine patients and 25 patient controls did not show an elevation of hsCRP under clozapine after 1 year and more. It is assumed that the clozapine-evoked increase of hsCRP is part of a transient acute-phase response. The underlying inflammatory process needs clarification.

Circadian rhythm of neutrophil counts and granulocyte macrophage-colony stimulating factor (GM-CSF) under clozapine treatment: a case report.

UNLABELLED: Agranulocytosis is a severe side effect of clozapine which requires stopping this medication immediately in the case of progressive neutropenia. There are, however, cases of benign neutropenia under clozapine that do not progress. The ability to predict progression vs. non-progression in neutropenia cases under clozapine would be highly valuable for avoiding unnecessary treatment withdrawals. In this context, we closely monitored circadian neutrophil counts and granulocyte macrophage-colony stimulating factor (GM-CSF) levels in a patient who had low normal neutrophil counts at baseline and developed neutropenia under clozapine treatment. METHODS: Venous blood samples were drawn in close intervals for 4 weeks. At several time points blood was sampled in the morning between 08:30 and 9:30 h and a second time in the afternoon between 14:00 and 15:00 h. RESULTS: The circadian rhythm of neutrophil counts and GM-CSF levels was unchanged. There was no progression to agranulocytosis, and clozapine could be continued. CONCLUSIONS: In view of the available literature and the presented case it is suggested that further studying of circadian profiles of neutrophil counts, neutrophil regulatory factors, such as GM-CSF, and their intercorrelation may help to find a biomarker of benign vs. malign neutropenia under clozapine.

Blood biomarkers of osteoporosis in mild cognitive impairment and Alzheimer's disease.

Previous studies revealed some comorbidity of Alzheimer's disease and osteoporosis not only for advanced disease, but also for the incipient conditions cognitive decline and decline of bone mineral density. To detect comorbidity with osteoporosis at a subclinical level, we studied concentrations of biochemical osteoporosis markers in blood plasma of subjects with mild cognitive impairment and mild Alzheimer's disease compared to subjects with primary osteoporosis and age-matched cognitively normal controls in an explorative approach. Regarding disease-spanning molecular pathology we also studied osteoprotegerin, a decoy receptor of RANKL and TRAIL. Equally increased C-terminal collagen fragments, marking bone catabolism, were seen in osteoporosis and Alzheimer's disease (+68%) versus controls. Osteocalcin, marking bone remodelling and anabolism, was concomitantly increased in osteoporosis (+63%), as a trend, and significantly in Alzheimer's disease (+76%). Osteoprotegerin was unchanged between patient groups and controls. 25 (OH) vitamin D plasma levels were low normal and of equal amount in all groups except for the osteoporosis group. These results point to increased bone catabolism and concomitant remodelling/anabolism unrelated to vitamin D state in mild Alzheimer's disease, but not in mild cognitive impairment. This corroborates previous findings of comorbidity of Alzheimer's disease with osteoporosis in the early disease course at the level of biochemical blood markers. Regarding osteoprotegerin, previously reported plasma level increases in Alzheimer's disease were not observed in this study, which does not rule out subtle changes to be detected in larger samples or the possibility that other components of osteoprotegerin pathways are affected in Alzheimer's disease.

New aspects of adipogenesis: radicals and oxidative stress.

Preadipocytes are multipotent adipogenic precursor cells that can be isolated from mature adipose tissue. They have been receiving increasing attention in the context of obesity, type 2 diabetes, and other nutrition-associated diseases. Understanding the physiological and pathophysiological processes in fat neo-formation, energy homeostasis, and adipose tissue physiology is the basis for research on metabolic diseases and the respective pharmaceutical intervention. While the hormonal influence on intracellular signaling in adipogenesis has been intensively investigated, the effects of free radical formation and oxidative stress have just started to gain scientific attention. This review summarizes the present knowledge on the main molecular pathways in preadipocyte maturation and focuses on recent findings indicating that besides hormonal stimuli reactive oxygen species (ROS) and free radicals may also interact with preadipocyte differentiation.

Accumulation of apoptotic cells in the epidermis of patients with cutaneous lupus erythematosus after ultraviolet irradiation.

OBJECTIVE: To examine whether apoptosis contributes to the pathogenesis of skin lesions in patients with cutaneous lupus erythematosus (CLE) after ultraviolet (UV) irradiation. METHODS: In situ nick translation and TUNEL were performed to detect apoptosis in 85 skin biopsy specimens from patients with various subtypes of CLE. Specimens from normal healthy donors and patients with polymorphous light eruption were used as controls. In addition to assessment of primary lesions, provocative phototesting was carried out to investigate events occurring secondary to UV irradiation during a very early stage of lesion formation. RESULTS: A significant increase in apoptotic nuclei was found in the upper epidermal layer of primary and UV light-induced skin lesions of CLE patients compared with controls. In tissue sections obtained from control subjects at 24 hours after a single exposure to UV light, a slight increase in the count of epidermal apoptotic nuclei was present as compared with skin tissue from CLE patients obtained under the same conditions before lesion formation. In sections obtained from controls at 72 hours after irradiation, a significant decrease in the apoptotic nuclei count was observed, consistent with a proper clearance of apoptotic cells in the period between 24 and 72 hours after irradiation. In striking contrast, the number of apoptotic nuclei increased significantly within this period in tissue sections from patients with CLE. CONCLUSION: These data support the hypothesis that apoptotic cells accumulate in the skin of patients with CLE after UV irradiation, as a result of impaired or delayed clearance. The nonengulfed cells may undergo secondary necrosis and release proinflammatory compounds and potential autoantigens, which may contribute to the inflammatory micromilieu that leads to formation of skin lesions in this disease.

Clozapine induces oxidative stress and proapoptotic gene expression in neutrophils of schizophrenic patients.

The present study examined cellular effects of the atypical antipsychotic drug clozapine on blood cells of treated patients with and without clozapine-induced agranulocytosis (CA). Blood from one patient who commenced clozapine treatment was examined at weekly intervals for 128 days. Olanzapine-treated (n = 5) and polymedicated (n = 14) schizophrenic patients, as well as healthy subjects (n = 19) and septic shock patients (n = 8), were studied for comparison. We observed dramatically increased numbers of native neutrophils stained for superoxide anion production (P < or = 0.005, n = 10) and significantly elevated expression levels of the proapoptotic genes p53 (P < or = 0.020), bax alpha (P < or = 0.001), and bik (P < or = 0.002) in all tested non-CA patients (n = 19) and CA patients (n = 4). In non-CA patients, the expression of these genes did not correlate to the percentage of apoptotic neutrophils (2.0% +/- 1.3%), but in CA patients about 37% of the neutrophils show morphologic signs of apoptosis (P < or = 0.001). Under G-CSF therapy of CA, the number of apoptotic neutrophils and the expression of the proapoptotic genes decreased significantly. In conclusion, high production of reactive oxygen species in neutrophils of clozapine-treated patients, together with increased expression of proapoptotic genes, suggests that neutrophils are predisposed to apoptosis in schizophrenic patients under clozapine therapy. The correlation between drug and proapoptotic markers was highest for clozapine and bax alpha as well as superoxide anion radicals. This indicates oxidative mitochondrial stress in neutrophils of clozapine-treated patients which probably contributes to the induction of apoptosis and sudden loss of neutrophils and their precursors in CA patients.