The relationship between oxidative stress and psychotic disorders in 22q11.2 deletion syndrome

BACKGROUND

22q11.2 Deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans. This condition is associated with a wide range of symptoms including immune and neuropsychiatric disorders. Notably, psychotic disorders including schizophrenia have a prevalence of ∼ 30%. A growing body of evidence indicates that neuroinflammation and oxidative stress (OS) play a role in the pathophysiology of schizophrenia. In this study, we aim to assess the interaction between 22q11.2DS, OS and schizophrenia.

METHODS

Blood samples were collected from 125 participants (including individuals with 22q11.2DS [n = 73] and healthy controls [n = 52]) from two sites: Sheba Medical Center in Israel, and University Hospital Gasthuisberg in Belgium. Baseline OS levels were evaluated by measuring Myeloperoxidase (MPO) activity. A sub-sample of the Israeli sample (n = 50) was further analyzed to examine survival of Peripheral Blood Mononuclear Cells (PBMCs) following induction of OS using vitamin K3.

RESULTS

The levels of MPO were significantly higher in all individuals with 22q11.2DS, compared to healthy controls (0.346 ± 0.256 vs. 0.252 ± 0.238, p =.004). In addition, when comparing to healthy controls, the PBMCs of individuals with 22q11.2DS were less resilient to induced OS, specifically the group diagnosed with psychotic disorder (0.233 ± 0.206 for the 22q11.2DS individuals with psychotic disorders, 0.678 ± 1.162 for the 22q11.2DS individuals without psychotic disorders, and 1.428 ± 1.359 for the healthy controls, p =.003, η2 = 0.207).

CONCLUSIONS

Our results suggest that dysregulation of OS mechanisms may play a role in the pathophysiology of the 22q11.2DS phenotype. The 22q11.2DS individuals with psychotic disorders were more sensitive to induction of OS, but did not present significantly different levels of OS at baseline. These results may be due to the effect of antipsychotic treatment administered to this sup-group. By elucidating novel molecular pathways, early identification of biochemical risk markers for 22q11.2DS and psychotic disorders can be detected. This can ultimately pave the way to the design of early and more precise interventions of individuals with 22q11.2DS.

Serum claudin-5 levels among patients with unipolar and bipolar depression in relation to the pro-inflammatory cytokine tumor necrosis factor-alpha levels

Accumulating evidence indicates that inflammation and neurovascular unit (NVU) dysfunction contribute to depression via disrupted blood-brain barrier (BBB) integrity. Claudin-5, an endothelial tight-junction protein expressed in the NVU and contributing to BBB integrity, has been implicated in psychiatric disorders, including major depressive disorder (MDD) and schizophrenia. In an animal model of depressive-like behavior, the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) was found to affect BBB permeability and claudin-5 expression of NVU endothelial cells. To the best of the authors' knowledge, this study is the first to assess the relationship between serum claudin-5 and TNF-α levels, during major depressive episodes (MDEs). Serum levels of claudin-5 and TNF-α of 40 patients diagnosed with current MDE [19 with MDD and 21 with bipolar disorder (BD)] and 28 matched healthy controls (HCs) were analyzed. Claudin-5 and TNF-α serum levels in the MDE group were significantly higher than in the HC one. Discrete analysis according to MDE type indicated significantly increased claudin-5 serum levels in BD but not in MDD patients, compared to HCs, even after controlling for confounders. In the MDE group, a significant positive correlation was found between claudin-5 and TNF-α serum levels. In complementary analysis, serum levels of the pro-inflammatory cytokine interleukin-6 were significantly higher among MDE patients compared to HCs, however, no significant correlation was found with claudin-5 levels. In conclusion, as indicated by preclinical studies, our clinical study suggests a possible specific interaction between the NVU/BBB marker claudin-5 and the inflammatory marker TNF-α in the pathogenesis of depression.

Blood brain barrier permeability increases with age in individuals with 22q11.2 deletion syndrome

22q11.2 deletion syndrome (22q11.2DS) is characterised by high rates of psychotic disorders and immune abnormalities. Blood-brain barrier (BBB) permeability is known to be a risk factor for schizophrenia and immune aberrations.

OBJECTIVE

To evaluate the relationship between psychosis and BBB permeability in this population.

METHODS

We examined two biomarkers for BBB permeability, s100β and neuron-specific enolase (NSE), in 22q11.2DS individuals with/without psychosis. The first cohort of this Israeli-Belgium study was comprised of 20 22q11.2DS adults (30.58 ± 9.42 years) afflicted with a psychotic disorder, another group of 69 non-psychotic 22q11.2DS adults (23.42 ± 8.36 years), and 58 healthy controls (26.39 ± 7.77 years). A second cohort was comprised of 18 non-psychotic 22q11.2DS Israeli children (5.83 ± 1.55 years) and 14 healthy controls (5.34 ± 1.43 years). NSE and s100β serum levels were detected in all participants.

RESULTS

Both factors were elevated in adults with 22q11.2DS compared to healthy controls, specifically in the non-psychotic sub-group. In contrast, there were no significant differences in their levels between the two groups of the paediatric cohort.

CONCLUSIONS

Increased BBB permeability seems to be a trait of 22q11.2DS that evolves sometime in early adulthood. Our findings are in line with previous reports on non-syndromic schizophrenia, and suggest potential novel neural pathways to psychosis in 22q11.2DS.

Keeping it simple: mental health assessment in the Gastroenterology Department - using the Hospital Anxiety and Depression Scale (HADS) for IBD patients in Israel

BACKGROUND

Depression and anxiety are common among inflammatory bowel disease (IBD) patients. Not only do they worsen quality of life, but also worsen the prognosis of the IBD. Yet, there are no widely accepted guidelines for screening for depression or anxiety in this population. The Hospital Anxiety and Depression Scale (HADS) is a self-administered questionnaire designed to measure anxiety and depression in the physically ill. The purpose of this study was to establish the utility of the HADS as a screening tool in IBD patients.

METHODS

Seventy-nine IBD patients (age 29.86 ± 8.36, 51.9% female, 77.2% Crohn's disease) were recruited consecutively at the day treatment unit, Gastroenterology Department, Sheba Medical Center. They were asked to complete the HADS, the Beck Depression Inventory (BDI), and the State-Trait Anxiety Inventory (STAI). The scores of the HADS depression and anxiety subscales were correlated with the BDI and STAI scores, and the rates of above-threshold scores were calculated and compared between the three questionnaires and findings from previous studies.

RESULTS

The two HADS subscales significantly correlated with and the BDI (r_s = .69, p < 0.001) and STAI state and trait anxiety (r_s = .853, p < 0.001; r _s = .744, p < 0.001, respectively). The usual HADS cut-off scores yielded adequate rate of anxiety but lower than expected depression rates.

CONCLUSIONS

Our findings suggest the HADS as a valid screening tool for anxiety and depression in IBD patients. We recommend administering it routinely in gastrointestinal (GI) follow-ups using a lower cut-off score for depression than anxiety (greater than 7 vs greater than 11, respectively).

Neutrophils to lymphocytes ratio and psychosis in 22q11.2 deletion syndrome - Clinical and scientific implications

BACKGROUND

Individuals with 22q11.2 deletion syndrome (22q11.2DS) are at risk for having both psychotic and immune disorders, thus, implying a possible link between the two. The aim of the current study was to evaluate the usefulness of the neutrophiles to leukocytes ratio (NLR), an inflammatory marker, as a bio-marker for overt and prodromal psychotic symptoms in 22q11.2DS.

METHODS

Forty-nine individuals with 22q11.2DS (13 with psychotic disorders and 36 without psychotic disorders) and 30 age- and sex-matched healthy controls underwent psychiatric evaluation using a structured psychiatric interview, the Scale of Prodromal Symptoms (SOPS) and the Global Assessment of Functioning (GAF) scale. Blood samples were collected from all participants on the day of assessment. NLR was calculated, compared among the study groups and correlated with SOPS and GAF scores. The non-psychotic 22q11.2DS group was further divided into high- and low-inflammation groups by NLR values and the analyses were done again.

RESULTS

NLR was higher in the psychotic- and the high-inflammation non-psychotic 22q11.2DS groups compared to the low-inflammation non-psychotic 22q11.2DS group and controls. In the high-inflammation non-psychotic 22q11.2DS group NLR increase was associated with an increase of total negative symptoms scores on SOPS and a decrease in GAF scores.

CONCLUSION

Our results suggest the potential utility of NLR as a bio-marker for psychotic disorders and subthreshold prodromal symptoms in 22q11.2DS. Furthermore, they imply that a disequilibrium between the innate and adaptive arms of the immune system facilitates the progression of psychosis in at risk populations. Further longitudinal studies are warranted to validate our findings, as this was a cross sectional observation.

Regulatory effect of lithium on hippocampal blood-brain barrier integrity in a rat model of depressive-like behavior

OBJECTIVES

Recent evidence has associated mood disorders with blood-brain barrier (BBB)/ neurovascular unit (NVU) dysfunction, and reduction in blood vessels coverage by the water channel aquaporin-4 (AQP4) immunoreactive astrocytes. Lithium is an established treatment for mood disorders, yet, its mechanism of action is partially understood. We investigated the effects of lithium on BBB integrity and NVU-related protein expression in chronic mild stress (CMS) rat model of depressive-like behavior.

METHODS

Male Wistar rats were exposed for 5 weeks to unpredictable mild stressors with daily co-administration of lithium chloride to half of the stressed and unstressed groups. Sucrose preference and open field tests were conducted to validate the depressive-like phenotype, and dynamic contrast-enhanced MRI analysis was utilized to assess BBB integrity in brain regions relevant to the pathophysiology of depression. Hippocampal AQP4 and claudin-5 expression were studied using immunofluorescence, western blot, and enzyme-linked immunosorbent assays.

RESULTS

Lithium administration to the stressed rats prevented the reductions in sucrose preference and distance traveled in the open field, and normalized the stress-induced hippocampal BBB hyperpermeability, whereas lithium administration to the unstressed rats increased hippocampal BBB permeability. Additionally, lithium treatment attenuated the decrease in hippocampal AQP4 to glial fibrillary acidic protein immunoreactivity ratio in the stressed rats and upregulated hippocampal claudin-5 and BDNF proteins expression.

CONCLUSIONS

Our findings suggest that lithium administration in a rat CMS model of depressive-like behavior is associated with attenuation of stressed-induced hippocampal BBB/NVU disruption. These protective effects may be relevant to the mode of action of lithium in depression.

Lack of association between unipolar or bipolar depression and serum aquaporin-4 autoantibodies

Aquaporin-4 (AQP4), an astrocyte water channel protein, is the target antigen of serum immunoglobulin G (IgG) autoantibody in neuromyelitis optica spectrum disorders (NMOsd), a group of inflammatory, demyelinating diseases of the central nervous system. Recently, a reduction in blood vessels coverage by AQP4-immunoreactive astrocytes was demonstrated in depressed patients, indicating a role for AQP4 in mood disorders. Moreover, a possible association between depression and serum AQP4-IgG was suggested in a case report of a treatment resistant depression (TRD) patient diagnosed with NMOsd with positive serum AQP4 autoantibodies. We investigated, for the first time, the presence of serum AQP4-IgG in patients with unipolar and bipolar depression and healthy controls (HCs). In this multicenter study, 25 major depressive disorder (MDD) and 25 bipolar disorder (BD) patients, during an acute major depressive episode (MDE), and 30 matched HCs were screened for the presence of serum AQP4-IgG, using a cell-based assay. The MDE patients underwent a repeated AQP4-IgG assessment at a 3-month follow-up visit. The MDE group (N = 50) had illness duration of 12.7 years (SD = 10.5), 12% of them were psychotropic medication-free and 26% were defined as TRD. All MDE patients and HCs, including three BD patients who experienced a manic switch, were seronegative for AQP4-IgG at baseline and follow-up assessments. In conclusion, contrary to our hypothesis, AQP4 autoantibodies were not detected in serum of unipolar and bipolar depressed patients. However, AQP4 may still play a role in the pathogenesis of mood disorders through different mechanisms of action such as altered brain AQP4 expression.

Increased circulatory IL-6 during 8-week fluoxetine treatment is a risk factor for suicidal behaviors in youth

OBJECTIVE

Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat anxiety and/or depression in pediatric populations. However, the response rates are low (approximately 50%). Moreover, SSRI use is frequently associated with adverse events (AE). Currently there are no available biomarkers for treatment response/AE. Identification of biomarkers predicting early response and/or AE could help maximize the benefit-risk ratio for the use of SSRIs, and accelerate matching of treatments to patients. Pro-inflammatory cytokines were proposed as potential biomarkers.

METHOD

Ninety-two patients (35 boys and 57 girls) with major depressive disorder and/or anxiety disorders, aged 13.90 ± 2.41 years, were treated with fluoxetine (FLX) for 8 weeks. Plasma concentrations of TNFα, IL-6, and IL-1β were measured by enzyme linked immunosorbent assays before and after FLX treatment. Clinical response and AE were measured using several clinical scales, including the Clinical Global Impression - improvement, Children's Depression Rating Scale-Revised, the Beck Depression Inventory, the Screen for Child Anxiety Related Emotional Disorders, the Columbia suicide severity rating scale, and the Suicide Ideation Questionnaire.

RESULTS

IL-6 levels increased after treatment only in the group of children who developed FLX-associated suicidality.

CONCLUSION

An increase in IL-6 levels during treatment may be a risk factor for the emergence of FLX-associated suicidality (OR = 1.70). Further studies are necessary to clarify the role and mechanism(s) of this cytokine in the pathogenesis of this life-threatening AE.

Exploring the potential association among sleep disturbances, cognitive impairments, and immune activation in 22q11.2 deletion syndrome

22q11.2 deletion syndrome (22q11.DS) is a neurogenetic disorder caused by a microdeletion in chromosome 22. Its phenotype includes high rates of psychiatric disorders, immune system abnormalities, and cognitive impairments. We assessed the quality of sleep in 22q11.2DS and its potential link to inflammatory markers and cognitive deficits. Thirty-three 22q11.2DS individuals and 24 healthy controls were studied. Sleep parameters were assessed by the Pittsburgh sleep quality index (PSQI) questionnaire and correlated with serum cytokine levels and cognitive functioning, measured using the Penn computerized neurocognitive battery (CNB). The 22q11.2DS individuals had significantly worse sleep quality scores than the controls, unrelated to the psychiatric or physical comorbidities common to 22q11.2DS. Interleukin 6 levels were correlated with the overall score of the PSQI questionnaire for nonpsychotic 22q11.2DS participants only. Several domains of the CNB were associated with poorer sleep quality, suggesting that cognitive impairments in 22q11.2DS may be at least partially explained by poor sleep quality. Our findings confirm sleep impairments in individuals with 22q11.2DS, which might negatively affect their cognitive functioning, and corroborate a potential role of immunological pathways in the 22q11.2DS neuro-phenotype.

Intracranial Transplantation of Pancreatic Islets Attenuates Cognitive and Peripheral Metabolic Dysfunctions in a Rat Model of Sporadic Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is often associated with brain insulin resistance and peripheral metabolic dysfunctions. Recently, we developed a model of sporadic AD associated with obesity-related peripheral metabolic abnormalities in Lewis rats using intracerebroventricular administration of streptozotocin (icv-STZ).

OBJECTIVE

We aimed to assess the effect of intracranially grafted pancreatic islets on cognitive and peripheral metabolic dysfunctions in the icv-STZ Lewis rats.

METHODS

AD-like dementia associated with obesity was induced in inbred Lewis rats using a single icv-STZ. Two months after icv-STZ, syngeneic islets (100 islets per recipient) were implanted in the cranial subarachnoid cavity of icv-STZ rats. Morris water maze and marble burying tests were used for studying cognitive and behavioral functions. Central and peripheral metabolic alterations were assessed by histological and biochemical assays.

RESULTS

The icv-STZ induced increases in food intake, body weight, and blood levels of insulin and leptin without alteration of glucose homeostasis. Grafted islets reduced body weight gain, food consumption, peripheral insulin resistance, and hyperleptinemia. Biochemical and histological analysis of the brain revealed viable grafted islets expressing insulin and glucagon. The grafted islets did not affect expression of brain insulin receptors and peripheral glucose homeostasis. Two months after islet transplantation, cognitive and behavioral functioning in transplanted rats were significantly better than the sham-operated icv-STZ rats. No significant differences in the locomotor activity between transplanted and non-transplanted icv-STZ rats were found.

CONCLUSIONS

Intracranial islet transplantation attenuates cognitive decline and peripheral metabolic dysfunctions providing a novel therapeutic approach for sporadic AD associated with peripheral metabolic dysfunctions.

[THERE IS ROOM FOR IMPROVEMENT: THE RATE OF CLOZAPINE USE AMONG PATIENTS WITH SCHIZOPHRENIA IN ISRAEL]

BACKGROUND

About a third of schizophrenia patients would not have sufficient clinical response to antipsychotic treatment. The only drug approved for this population is clozapine, yet worldwide reports suggest underuse of clozapine and significant delay in initiating treatment.

OBJECTIVES

To assess, for the first time in Israel, the rate of clozapine use in patients with schizophrenia.

METHODS

A retrospective cohort study of "Clalit Health Services" electronic records was conducted. People diagnosed with schizophrenia (F.20 ICD 10 code) who had at least one prescription filled for clozapine were followed up between 2012 and 2014.

RESULTS

Of 28,983 people diagnosed with schizophrenia, clozapine was prescribed and purchased by 1817 (6.5%) patients during the study period. In addition, 60% of patients with clozapine had polytherapy with other antipsychotic compound or lithium. Polytherapy was associated with HR of 2.1 for morality during the follow-up period.

CONCLUSIONS

Clozapine is underutilized in Israel, similar to reports from other countries. Moreover, the data suggests that when treatment is given it is not optimized, as reflected by high rates of polytherapy associated with increased mortality. Using therapeutic drug monitoring, now available in Israel, for clozapine might increase clozapine dosage optimization.

Elevated Proinflammatory Markers in 22q11.2 Deletion Syndrome Are Associated With Psychosis and Cognitive Deficits

OBJECTIVE

22q11.2 deletion syndrome (22q11.2DS) is a neurogenetic disorder whose phenotype includes high rates of a schizophrenia-like psychotic disorder and immune system abnormalities. Thus, 22q11.2DS is an ideal model for studying the relationship between psychosis and inflammation. The aim of the present study was to identify inflammatory markers that may play a role in the pathophysiologic pathways associated with psychosis and cognitive deficits in 22q11.2DS.

METHODS

Forty-nine individuals with 22q11.2DS (13 with psychotic disorders according to DSM-IV criteria and 36 without psychotic disorders) and 30 age- and sex-matched healthy controls underwent psychiatric and cognitive assessments at an outpatient clinic. Blood samples from all participants were analyzed for C-reactive protein (CRP), interleukin (IL)-6, IL-10, tumor necrosis factor alpha (TNFα), and IL-1 receptor antagonist levels. The study was conducted between August 2014 and September 2015.

RESULTS

The 22q11.2DS participants had elevated levels of CRP (P = .004), IL-6 (P = .001), TNFα (P < .001), and IL-10 (P = .028) compared with controls. Furthermore, the psychotic 22q11.2DS participants had higher levels of IL-6 (P < .001) and IL-6/IL-10 ratio (used as an indicator for proinflammatory activation, P < .001) compared with the nonpsychotic 22q11.2DS individuals and controls. IL-6 levels and the IL-6/IL-10 ratio correlated with the severity of the cognitive deficits in the 22q11.2DS participants.

CONCLUSIONS

Our preliminary findings indicate an involvement of inflammatory processes in the pathophysiology of psychosis and cognitive deficits in 22q11.2DS and are in line with the accumulating evidence for the role of neuroinflammation in nonsyndromic schizophrenia.

Exercise, Dehydroepiandrosterone (DHEA), and Mood Change: A Rationale for the "Runners High"?

BACKGROUND

Although exercise has been shown to improve mood and well-being, the precise mechanism remains unknown. Neurosteroids are important neuroactive molecules with demonstrated involvement in several neurophysiological and disease processes. Previous research has noted neurosteroid changes in dehydroepiandrosterone (DHEA) levels following exercise.

OBJECTIVES

To determine whether changes in DHEA levels are associated with mood improvement after exercise and whether there are any differences in the effects on younger and older individuals.

METHODS

Individuals ≤ 50 years of age or > 65 years of age were recruited for study participation. Before and after 30 minutes of a standardized cycling regimen, each patient provided a blood sample and completed a questionnaire on mood and well-being.

RESULTS

Findings confirmed a significant increase in DHEA levels post-exercise. A decrease in negative factors (fatigue, tension, depression, anger) and an increase in positive mood factors were noted. No difference in change of measures was noted between younger and older subjects. A positive correlation was noted between mood change and DHEA blood-level changes in older subjects. Among older males, DHEA appeared to be associated with mood change after exercise.

CONCLUSIONS

While preliminary, findings indicate a possible association between mood improvement following exercise and DHEA blood level changes. Understanding the biological mechanisms of exercise-induced mood changes is critical to utilizing exercise as a treatment for mood disorders.

Intracerebroventricular Streptozotocin Induces Obesity and Dementia in Lewis Rats

BACKGROUND

Animal models of dementia associated with metabolic abnormalities play an important role in understanding the bidirectional relationships between these pathologies. Rodent strains develop cognitive dysfunctions without alteration of peripheral metabolism following intracerebroventricular administration of streptozotocin (icv-STZ).

OBJECTIVE

We aimed to estimate the effect of icv-STZ on cognitive functions and peripheral metabolism in Lewis rats, which are rarely used for the induction of cognitive abnormalities.

METHODS

Inbred adult Lewis rats were treated with single icv-STZ (3 mg/kg). Cognitive functions were assessed using Morris water maze (MWM) test and locomotion by the Open Field test. Metabolic alterations were studied using histological and biochemical analysis of brain and peripheral tissues.

RESULTS

The icv-STZ induced rapid weight decline during the first two weeks. Thereafter, the rats showed an accelerated weight gain. Three months after the icv-STZ treatment, the rats were severely obese and revealed fatty liver, pancreatic islet hypertrophy, significantly elevated levels of blood insulin, leptin, and adiponectin, but intact peripheral glucose homeostasis. The icv-STZ rats expressed amyloid-β deposits in blood vessels of leptomeningeal area, microgliosis, astrogliosis, and spongiosis in fimbria-fornix area of hippocampus. Locomotor activities of icv-STZ treated and sham-operated rats were similar. In the MWM test, the icv-STZ treated rats demonstrated severely impaired spatial learning during both acquisition and reversal phases.

CONCLUSIONS

Icv-STZ treated Lewis rats develop severe dementia associated with obesity and peripheral metabolic abnormalities. This animal model may be useful for exploring the pathophysiological relationship between obesity and dementia and provides a new tool for development of effective therapy.

Association between serum levels of glutamate and neurotrophic factors and response to clozapine treatment

Clozapine is the only available therapy for about 30% of schizophrenia patients otherwise refractory to antipsychotics. Unfortunately, the mechanism of action of the drug is still unknown and there are no biomarkers that can predict a positive response to clozapine. We aimed to examine serum neurotrophins and glutamate levels as putative biomarkers for clozapine response based on the hypothesized mode-of-action of the compound. Blood samples of 89 chronic schizophrenia patients maintained on clozapine were analyzed in a cross-sectional design. Serum brain derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), neurotrophic growth factor (NGF), glial derived neurotrophic factor (GDNF) and glutamate were determined. Differences between responders and non-responders to clozapine and correlation between clinical and biological measures were analyzed. Our sample consisted of 54 (61%) responders and 35 (39%) non-responders. Responders had higher mean BDNF levels than non-responders (2066±814 vs. 1668±820pg/ml, p<0.05. respectively) and higher serum glutamate levels (1.61±2.2 vs. 0.66±0.9pg/ml, respectively, p<0.05). Furthermore, there was a significant correlation between serum glutamate levels and positive symptoms among the clozapine-responder group (rho=0.47, p<0.005). High serum levels of BDNF and glutamate were associated with response to clozapine, while glutamate levels correlated with the psychosis severity in clozapine responders only. Large-scale, prospective longitudinal studies are needed to support these findings and the assumption that serum glutamate and BDNF can discriminate between clozapine responders and non-responders.

An exploratory study of adolescent response to fluoxetine using psychological and biological predictors

Background

Not enough is known about predicting therapeutic response to serotonin-specific reuptake inhibitors, and specifically to fluoxetine. This exploratory study used psychological and biological markers for (retrospective) prediction of treatment-response to fluoxetine in depressed and/or anxious adolescents.

Methods

Forty-one consecutive adolescent outpatients with a primary diagnosis of severe affective and/or anxiety disorders were assessed and treated with an open-label 8-week trial of fluoxetine. Type D personality was assessed with the 14-item questionnaire, the DS14. In addition, TNFα, IL-6, and IL-1b were measured pre- and post-treatment.

Results

There was an elevation of Type D personality in patients, compared to the adolescent population rate. Post-treatment, 44% of patients were classified as non-responders; the relative risk of non-response for Type D personality patients was 2.8. Binary logistic regression predicting response vs. non-response showed a contribution of initial TNFα levels as well as Type D personality to non-response.

Conclusions

In this exploratory study, the most significant contributor to non-response was Type D personality. However, the measurement of Type D was not prospective, and thus may be confounded with psychiatric morbidity. The measurement of personality in psychiatric settings may contribute to the understanding of treatment response and have clinical utility.

BDNF overexpression prevents cognitive deficit elicited by adolescent cannabis exposure and host susceptibility interaction

Cannabis abuse in adolescence is associated with increased risk of psychotic disorders. Δ-9-tetrahydrocannabinol (THC) is the primary psychoactive component of cannabis. Disrupted-In-Schizophrenia-1 (DISC1) protein is a driver for major mental illness by influencing neurodevelopmental processes. Here, utilizing a unique mouse model based on host (DISC1) X environment (THC administration) interaction, we aimed at studying the pathobiological basis through which THC exposure elicits psychiatric manifestations. Wild-Type and dominant-negative-DISC1 (DN-DISC1) mice were injected with THC (10 mg/kg) or vehicle for 10 days during mid-adolescence-equivalent period. Behavioral tests were conducted to assess exploratory activity (open field test, light-dark box test) and cognitive function (novel object recognition test). Electrophysiological effect of THC was evaluated using acute hippocampal slices, and hippocampal cannabinoid receptor type 1 and brain-derived neurotrophic factor (BDNF) protein levels were measured. Our results indicate that THC exposure elicits deficits in exploratory activity and recognition memory, together with reduced short-term synaptic facilitation and loss of BDNF surge in the hippocampus of DN-DISC mice, but not in wild-type mice. Over-expression of BDNF in the hippocampus of THC-treated DN-DISC1 mice prevented the impairment in recognition memory. The results of this study imply that induction of BDNF following adolescence THC exposure may serve as a homeostatic response geared to maintain proper cognitive function against exogenous insult. The BDNF surge in response to THC is perturbed in the presence of mutant DISC1, suggesting DISC1 may be a useful probe to identify biological cascades involved in the neurochemical, electrophysiological, and behavioral effects of cannabis related psychiatric manifestations.

The Relationship Between Plasma Cytokine Levels and Response to Selective Serotonin Reuptake Inhibitor Treatment in Children and Adolescents with Depression and/or Anxiety Disorders

OBJECTIVE

In adults there is growing evidence that antidepressant (AD) treatment results in a decline in inflammatory cytokines. This is the first report, to our knowledge, of the relationship between response to selective serotonin reuptake inhibitor (SSRI) treatment for anxiety and/or depression and cytokine levels in children and adolescents.

METHODS

Forty-one patients who met Diagnostic and Statistical Manual for Mental Disorders, 4th ed. (DSM-IV) criteria for major depressive disorder (MDD) or anxiety disorders participated in study. Their ages ranged from 9 to 18 (14.12 ± 2.30) years. The patients were treated with fluoxetine for 8 weeks. Plasma concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β were measured by enzyme linked immunosorbent assays (ELISA) before and after fluoxetine treatment. Clinical response was measured with several scales, including the Children's Depression Rating Scale-Revised (CDRS-R), the Beck Depression Inventory (BDI), and the Screen for Child Anxiety Related Emotional Disorders (SCARED) Results: The overall response rate was 56%. Antidepressant treatment significantly reduced TNF-α levels (p = 0.037), with no significant changes in the levels of IL-6 and IL-1β. All three proinflammatory cytokines were significantly (p < 0.05) higher in SSRI-refractory than in SSRI-responsive patients.

CONCLUSIONS

Higher levels of TNF-α, IL-6, and IL-1β might predict nonresponse to fluoxetine treatment in children.

The association between serum creatine kinase, mood and psychosis in inpatients with schizophrenia, bipolar and schizoaffective disorders

Previous studies demonstrated levels of serum CK (sCK) in the majority of patients undergoing acute psychosis. Records of 1054 patients hospitalized in Geha Mental Health Center during the study period were analyzed. Of them, 743 have been diagnosed with schizophrenia (Sz), 170 with schizoaffective disorder (SzA), and 158 with bipolar disorder (BP-I). Baseline sCK and PANSS values were obtained from each patient upon admission. Our results show that LnsCK is higher in patients with BP-I in comparison with patients with SZ, but not significantly different compared to patients with SzA. A multivariate analysis using linear regression model in which LnsCK was predicted by factors such as PANSS-total and sub-scores, IM injection, BMI, gender, and age among patients at each admission, revealed that PANSS-depression was inversely associated with LnsCK level in SzA and BP-I and not in SZ. A positive association was found between PANSS-total and sCK in SzA and BP-I; however, PANSS-positive scores correlated with sCK only in SzA. After controlling for confounders, it seems that sCK level is associated with the both affective and psychotic components. Serum CK may serve as a biomarker for affective exacerbation rather than psychosis.

Intracranial pancreatic islet transplantation increases islet hormone expression in the rat brain and attenuates behavioral dysfunctions induced by MK-801 (dizocilpine)

The treatment of rodents with non-competitive antagonist of the N-Methyl-D-aspartate (NMDA) receptor, MK-801 (dizocilpine), induces symptoms of psychosis, deficits in spatial memory and impairment of synaptic plasticity. Recent studies have suggested that insulin administration might attenuate the cognitive dysfunctions through the modulatory effect on the expression of NMDA receptors and on the brain insulin signaling. Intrahepatic pancreatic islet transplantation is known as an efficient tool for correcting impaired insulin signaling. We examined the capacity of syngeneic islets grafted into the cranial subarachnoid cavity to attenuate behavioral dysfunctions in rats exposed to MK-801. Animals were examined in the open field (OF) and the Morris Water Maze (MWM) tests following acute or subchronic administration of MK-801. We found well-vascularized grafted islets expressing insulin, glucagon and somatostatin onto the olfactory bulb and prefrontal cortex. Significantly higher levels of insulin were detected in the hippocampus and prefrontal cortex of transplanted animals compared to the non-transplanted rats. All animals expressed normal peripheral glucose homeostasis for two months after transplantation. OF tests revealed that rats exposed to MK-801 treatment, showed hyper-responsiveness in motility parameters and augmented center field exploration compared to intact controls and these effects were attenuated by the grafted islets. Moreover, in the MWM, the rats treated with MK-801 showed impairment of spatial memory that were partially corrected by the grafted islets. In conclusion, intracranial islet transplantation leads to the expression of islet hormones in the brain and attenuates behavioral and cognitive dysfunctions in rats exposed to MK-801 administration without altering the peripheral glucose homeostasis.

Effects of the anti-multiple sclerosis immunomodulator laquinimod on anxiety and depression in rodent behavioral models

Laquinimod is a novel oral immunomodulatory drug for the treatment of multiple sclerosis (MS). Considering the frequent co-morbidity of MS with anxiety and depression, we sought to assess the antidepressant and anxiolytic effects of laquinimod in mouse models. Laquinimod (0.5-25 mg/kg), fluoxetine (10 mg/kg) or vehicle were administered for 4-14 days to adult Balb/c mice, followed by behavioral tests and brain BDNF analysis. Following a 4-day administration of laquinimod (5 and 25 mg/kg), an increase in motivated behavior was observed in the forced swim test (p < 0.01 vs. controls). In the open field test, laquinimod (0.5-5 mg/kg), but not fluoxetine, significantly increased motility (p < 0.05), whereas both decreased anxiety behavior (p < 0.01), evident only for laquinimod (5 mg/kg) in the elevated plus maze (p < 0.05). Following 7 days of administration, both drugs decreased anxiety behavior in the elevated plus maze and marble burying tests (p < 0.001 and p < 0.02, respectively). After 14 days, only laquinimod (5 mg/kg) demonstrated anxiolytic efficacy in the open field test (p < 0.05), with evidence of increased BDNF in response to 5-25 mg/kg in the hippocampus, but not frontal cortex (p < 0.05). In conclusion, laquinimod may possess anxiolytic and antidepressant effects, possibly associated with hippocampal BDNF increase, offering promise for MS patients suffering from psychiatric co-morbidity.

Dominant negative DISC1 mutant mice display specific social behaviour deficits and aberration in BDNF and cannabinoid receptor expression

OBJECTIVES. Disrupted in schizophrenia 1 (DISC1) is considered the most prominent candidate gene for schizophrenia. In this study, we aimed to characterize behavioural and brain biochemical traits in a mouse expressing a dominant negative DISC1mutant (DN-DISC1).

METHODS

DN-DISC1 mice underwent behavioural tests to evaluate object recognition, social preference and social novelty seeking. ELISA was conducted on brain tissue to evaluate BDNF levels. Western blot was employed to measure BDNF receptor (TrkB) and cannabinoid receptor CB1.

RESULTS

The mutant DISC1 mice displayed deficits in preference to social novelty while both social preference and object recognition were intact. Biochemical analysis of prefrontal cortex and hippocampus revealed a modest reduction in cortical TrkB protein levels of male mice while no differences in BDNF levels were observed. We found sex dependent differences in the expression of cannabinoid-1 receptors.

CONCLUSIONS

We describe novel behavioural and biochemical abnormalities in the DN-DISC1 mouse model of schizophrenia. The data shows for the first time a possible link between DISC1 mutation and the cannabinoid system.

Mesenchymal stem cells protect from sub-chronic phencyclidine insult in vivo and counteract changes in astrocyte gene expression in vitro

Mesenchymal stem cells (MSCs) are an attractive cell source for regenerative medicine strategies in brain diseases. Experimental studies have shown that repeated administration of phencyclidine (PCP) leads to schizophrenia-like behavioral changes in mice. The aim of the present study was to explore the effectiveness of MSC transplantation into the hippocampus in attenuating PCP-induced social behavior deficits. PCP was administered subcutaneously to C57bl mice (10mg/kg daily) for 2 weeks. On the first day of PCP administration, adult human MSCs were transplanted into the hippocampus. A week after the last PCP dose, the mice underwent social preference testing. MSC transplantation was associated with a significant reduction in the adverse social behavior induced by PCP. Immunohistochemical analysis revealed that the stem cells survived in the mouse brain, and hippocampal Western blot analysis revealed a statistical trend towards a decrease in cleaved caspase 3 protein levels in the stem cell treated group. Upon in vitro co-culture of astrocytes and MSCs, the MSCs, in the presence of PCP, positively regulated astrocyte expression of genes involved in glutamate metabolism and antioxidant defenses. These findings suggest that MSC transplantation into the hippocampus may serve as a novel neuroprotective tool for the treatment of the PCP-induced schizophrenia-like social endophenotype. The mechanism underlying the beneficial behavioral effect may involve modulation of host astrocyte functioning, including glutamate processing and antioxidant capacity.

Neuroprotective and procognitive effects of sertraline: in vitro and in vivo studies

Selective serotonin reuptake inhibitors (SSRIs) stimulate synaptic plasticity and neurogenesis, most likely via the MAP-kinase signal transduction pathway (by phosphorilation of ERK) and by stimulating neurotrophic factors such as brain derived neurotrophic factor (BDNF) and the neuroprotective protein (Bcl-2). Using human neuroblastoma cells (SHSY5Y), we found that sertraline and its derivative, desmethylsertraline, at low concentrations (1-10 μM), induced potent neurotrophic activity. Subsequently, we have treated for 21 days young and aged mice with sertraline. Sertraline in certain doses improved significantly spatial memory learning, in both young and old mice. Sertraline treatment resulted in up-regulation of brain BDNF, phospho-ERK and Bcl-2 that may be involved in the pro-cognitive effect of sertraline.

Immunomodulatory effect of sertraline in a rat model of rheumatoid arthritis

OBJECTIVE

Previous studies suggest that selective serotonin reuptake inhibitors (SSRIs) modulate immune system functionality. SSRIs are the preferred treatment for major depressive disorder (MDD). A high rate of MDD is observed in rheumatoid arthritis (RA) patients. The aim of this study was to evaluate immunological effects of SSRIs in a rat model of RA.

METHODS

Adjuvant arthritis was induced in 8-week-old Lewis rats; in the first set of experiments following the induction, 15.3 or 30.6 mg/kg of sertraline was daily injected into the ankle joint of the left rear leg. Clinical disease activity was evaluated and the findings compared with the 3 untreated legs and with control groups given methotrexate (MTX) or vehicle only at the same site. In a second set of experiments, the effect of 5, 25 and 50 mg/kg daily oral sertraline was evaluated in the same rat model. Splenocyte viability and inflammatory mediators were evaluated.

RESULTS

The sertraline-treated rats showed a significant reduction in clinical arthritis compared to controls, at all doses given, accompanied by a significant increase in interleukin 10 and a decrease in tumor necrosis factor-α levels and cycloxygenase-2 production, without lymphotoxicity. There was no significant difference from MTX, the first-line treatment for RA patients. Oral sertraline had a significant anti-inflammatory effect at all doses. There was no treatment × time effect.

CONCLUSION

The beneficial effects of sertraline in this rat model of arthritis have clinical implications for its use in humans. Large-scale clinical efficacy trials are needed.

The immunomodulatory effect of the antidepressant sertraline in an experimental autoimmune encephalomyelitis mouse model of multiple sclerosis

BACKGROUND

We have previously demonstrated the immunomodulatory activity of some selective serotonin reuptake inhibitors.

OBJECTIVES

In this research, we performed an in vivo/ex vivo study to evaluate the potential immunosuppressive effect of sertraline in an experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis.

METHODS

Mice (C57/bl EAE) were treated with sertraline (5 mg/kg) or dexamethasone (1 mg/kg) 7 days after EAE induction and then 3 times weekly (for 3 weeks).

RESULTS

Sertraline modestly improved the clinical score of EAE and attenuated the disease-induced weight loss. Sertraline also significantly decreased ex-vivo splenocyte viability, proliferation and secretion of pro-inflammatory cytokines in EAE mice.

CONCLUSIONS

We suggest that sertraline might be an add-on option for multiple sclerosis treatment.

Proapoptotic and chemosensitizing effects of selective serotonin reuptake inhibitors on T cell lymphoma/leukemia (Jurkat) in vitro

While selective serotonin reuptake inhibitors (SSRIs) are commonly used for psychiatric indications, evidence implies them to possess anti-cancerous properties as well. We evaluated such in vitro effects in malignant T cells (Jurkat), finding that exposure to high concentrations of sertraline (IC(50)=9.5 microM) or paroxetine (IC(50)=18 microM) yielded a considerable reduction in cellular viability, exceeding equimolar doses of the chemotherapeutics vincristine and cyclophosphamide (P<0.015). The cytotoxic effects included both inhibition of proliferation and induction of apoptosis, demonstrated by decreased [3H] thymidine incorporation and increased activity of the caspase-3 enzyme, as well as a decrease in the expression of the Bcl-2 proto-oncogene. No effect on c-Jun or ERK was observed, rendering the complete mechanism yet to be fully elucidated. When combined with chemotherapy, sertraline (7.5 microM) markedly enhanced the effects of both vincristine and doxorubicin, suggesting SSRI antidepressants as potential new chemosensitizers in chemotherapeutic regimens, pending further in vivo research.

Effect of exposure to selective serotonin reuptake inhibitors in utero on fetal growth: potential role for the IGF-I and HPA axes

To investigate the possible effect of fetal exposure to selective serotonin reuptake inhibitors (SSRIs) on somatic growth and on hormones of the hypothalamic-pituitary-adrenal (HPA) and insulin-like growth factor (IGF)-I axes, we compared the anthropometric parameters and hormonal profile of 21 SSRI-exposed infants and 20 matched controls. The SSRI group was characterized by lower crown-heel length (p < 0.01), smaller head circumference (p = 0.08), and higher percentage of infants with birth weight, birth length, and head circumference below the 10th percentile (p < 0.045, p = 0.08, p < 0.04, respectively), in addition to a significantly lower cord blood level of cortisol (p < 0.03) and higher level of thyroid-stimulating hormone (TSH) (p < 0.004). Infants exposed to citalopram had a lower cord blood IGF-I level than infants exposed to paroxetine (p < 0.001) and controls (p < 0.003). Placental IGF-I receptor (IGF-IR) expression was significantly higher in the SSRI group than in controls (p < 0.01). Urine 5-hydroxyindoleacetic acid (5-HIAA) level was negatively correlated with birth weight (r = -0.71, p < 0.025) and with dehydroepiandrosterone (DHEA) level (r = -0.71, p < 0.025). The Finnegan score was correlated with dehydroepiandrosterone sulfate (DHEAS) (r = 0.8, p < 0.005) and cortisol (r = 0.62, p = 0.05). Fetal exposure to SSRIs causes impaired intrauterine growth accompanied by alterations in the IGF-I and HPA axes. The findings may raise concern regarding maternal use of SSRIs during pregnancy.

Evaluation of the potential anti-cancer activity of the antidepressant sertraline in human colon cancer cell lines and in colorectal cancer-xenografted mice

Evidence has been provided of the anti-proliferative activity of certain antidepressants, mainly the selective serotonin reuptake inhibitors (SSRIs). We tested the effect of different antidepressants on cell viability and proliferation of human colorectal carcinoma cell lines HT29 and the multi-drug resistant (MDR) LS1034. The SSRIs, paroxetine and sertraline, induced a dose-dependent inhibition of cell viability and proliferation in the two cell lines (IC50 8-15 micro M). When compared to cytotoxic agents e.g. doxorubicin, vincristine and 5-fluorouracil, the SSRIs showed comparable activity (HT29) or a superior effect (LS1034). Using flow cytometry analysis, we found that the two SSRIs arrested cells at the G0/G1 stage and stimulated DNA fragmentation in a dose-dependent manner. The SSRIs (10 and 20 microM) increased caspase-3 activation. Western blot analysis showed an increase after 24 h in c-Jun and a decrease in the expression of the anti-apoptotic protein Bcl-2. The results suggest a proapoptotic activity for the active SSRIs accompanied by mitogen-activated protein kinase cascade activation and Bcl-2 inhibition. In vivo, we used CD1 nude mice xenografted subcutaneously with HT29 cells. On day 8, after cell inoculation sertraline or paroxetine (15 mg/kg x3/week i.p.) were administered to animals (6/group), which were monitored weekly (for 5 weeks) for tumor volume and body weight. At 5 weeks, the animals survived, with no significant difference in body weight. Sertraline, though not paroxetine, significantly inhibited tumor growth. Collectively, our results suggest that the widely-used antidepressant, sertraline, possesses a potential anti-tumor activity, which circumvents the MDR mechanism. Since SSRI therapy is frequently indicated in cancer patients, the use of sertraline in colon cancer patients with co-morbidity of depression seems attractive.

Relationship between antidepressants and IGF-1 system in the brain: possible role in cognition

Antidepressants facilitate neuroplasticity by stimulating trophic factors. This study evaluated the effect of fluoxetine (FLX) treatment on insulin-like growth factor-1 (IGF-1) in the rat brain and its role in the effect of FLX on cognition. IGF-1 receptor (IGF-1R) protein expression and IGF-1 mRNA levels were assessed in rat frontal cortex (FC) and hippocampus, in FLX-treated [15 mg/kg, orally; 3 (acute) or 21 (repeated) days] male Wistar rats. Rats were subjected to the Morris Water Maze test. Acute FLX administration decreased IGF-1 mRNA levels in the FC and hippocampus and increased IGF-1R levels in the FC. Repeated FLX increased both mRNA and IGF-1R levels in the FC. Repeated, but not acute, FLX treatment decreased IGF-1 mRNA in the hippocampus. FLX did not affect cognitive performance. Thus, repeated FLX treatment leads to upregulation of IGF-1 system is FC. It is possible that FLX affect FC neuroplasticity through activation of the IGF-1 system.

Evidence for an inhibitory immunomodulatory effect of selected antidepressants on rat splenocytes: possible relevance to depression and hyperactive-immune disorders

Antidepressants have been found to possess antiproliferative effect. In the immune system depression may activate pro-inflammatory cytokines. Therefore, the aim of this study was to assess the immunomodulatory activity of antidepressants in naïve rat. Rat splenocytes were activated with con A and treated with paroxetine, sertraline or clomipramine ex vivo. We found that the antidepressants inhibit cell viability and proliferation at IC50 of 5-8 microM of mitogen-stimulated rat splenocytes. This inhibitory effect was accompanied by cell cycle arrest and increase in apoptotic events as assayed by FACS. Moreover, antidepressants decrease the secretion of the TH1 factor--TNFalpha. In addition, the antidepressants reduced the expression of the enzyme cyclooxygenase2 which is involved in inflammation. On the cellular level we show the up-regulation of MAPK death signaling pathway and suppression of the anti-apoptotic factor--Bcl-2. These findings reveal the immunomodulatory effect of the selected antidepressants. These data suggest a novel use of antidepressants or their derivatives.

Immunomodulatory effect of selective serotonin reuptake inhibitors (SSRIs) on human T lymphocyte function and gene expression

Antidepressants have an antiproliferative effect in some cell lines. Depression may be associated with activation of some pro-inflammatory cytokines. Therefore, we evaluated the ex-vivo immunomodulatory effect of selective serotonin reuptake inhibitors (SSRIs) in T cells. We found that the SSRIs, paroxetine and sertraline decreased T-cell viability with IC50 around 10 microM. The inhibition obtained with exposure to the SSRIs was more pronounced than that achieved with dexamethasone. Moreover, these SSRIs inhibit the secretion of the TH1 factor-tumor necrosis factor(TNF)alpha from the cells. On the molecular level, the SSRIs suppressed signal transducer and activator of transcription 3 (Stat3) and cyclooxygenase(Cox)2 protein expression. The inhibitory effects were accompanied by alterations in gene expression as assessed in the gene array. These findings reveal an immunomodulatory effect of the SSRIs paroxetine and sertraline in human T cells. The clinical implications of our findings merit further investigation.

Phenothiazines induce apoptosis in a B16 mouse melanoma cell line and attenuate in vivo melanoma tumor growth

Phenothiazines and related antipsychotics were reported to have an antiproliferative effect in several tissue cultures. The aims of this study were: a) to screen in vitro, the potential anti-cancer activity of phenothiazines in wild-type and multi-drug resistant (MDR) B16 mouse melanoma cell lines; and b) to determine the in vivo anti-tumor effect of an in vitro selected highly potent phenothiazine (thioridazine) in a murine melanoma model. The following phenothiazines were evaluated: perphenazine, fluphenazine, thioridazine trifluoperazine and chlorpromazine. All agents induced a dose-dependent decrease in cell viability in wild-type and in MDR B16 melanoma cells. Thioridazine displayed the highest antiproliferative activity. Flow cytometric analyses of 24-h treated B16 melanoma cells revealed an increase in fragmented DNA (16.3 vs 71.3% and 87.2% in controls, 25 microM and 50 microM thioridazine-treated, respectively). Apoptosis was confirmed by co-staining of thioridazine-treated B16 cells (12.5 microM) with propidium iodide and Hoechst 33342 reagents. Caspase-3 expression, a typical mediator of apoptosis, was markedly increased following a 4-h exposure of B16 cells to thioridazine (25 microM and 50 microM). This increase could be blocked by a specific caspase-3 inhibitor. In vivo studies were performed using female C57/Bl mice. Animals were inoculated with wild-type B16 cells by i.v. injection into the tail vein. Mice were treated with thioridazine (10 and 15 mg/kg x3/week i.p. or 15, and 25 mg/kg/day p.o.) and control animals received saline. Mice were monitored for 21-30 days. Body weight was recorded. After autopsy, the lung weight and number of pulmonary melanoma colonies were determined. Thioridazine administration (i.p. or p.o.) resulted in the reduction of lung tumor burden and an increase in mice survival. In conclusion, several phenothiazines, and particularly thioridazine, induced apoptosis of B16 melanoma cells and demonstrated in vivo anti-tumor activity.

Fer kinase sustains the activation level of ERK1/2 and increases the production of VEGF in hypoxic cells

Fer is a nuclear and cytoplasmic tyrosine kinase that is ubiquitously expressed in mammalian cells. Herein we show that Fer sustains a key signaling step in hypoxic cells. Knock-down of the Fer protein using a specific siRNA decreased the production of VEGF by the hypoxic cells. Conversely, ectopic expression of this kinase led to an elevated production of VEGF under hypoxia. At the molecular level, Fer was found to associate with ERK1/2 and this interaction was intensified under hypoxia. Moreover, Fer increased the activation levels of ERK1/2, and reducing the level of Fer, impaired the activation of ERK1/2 in hypoxic cells. Blocking the MEK-ERK1/2 signaling pathway with the MEK inhibitors U0126, or PD98059 led to the abrogation of ERK1/2 activity in hypoxic cells, an effect that was counteracted by Fer. Hence, Fer sustains the activation of ERK1/2 and increases the production of VEGF in hypoxic cells, without affecting the MEK-ERK signaling pathway.

Fer is a downstream effector of insulin and mediates the activation of signal transducer and activator of transcription 3 in myogenic cells

Fer is an intracellular tyrosine kinase that associates with signal transducer and activator of transcription 3 (Stat3) in mammalian cells. However, the signaling pathways in which this interaction plays a functional role have not been revealed. Herein, we show that insulin up-regulates the levels of the fer mRNA and Fer protein in myoblasts that undergo insulin-induced myogenic differentiation. Moreover, insulin directs the interaction of Fer with members of the Janus family of tyrosine kinases (Jak)-Stat3 signaling pathway. Although in untreated cells Fer binds Jak1 and its tyrosine phosphorylation level is low, insulin treatment induced the phosphorylation of Fer and its dissociation from Jak1. The up-regulation of Fer and its dissociation from Jak1 were accompanied by an augmented association of activated Fer with Stat3 and by a concomitant increase in the tyrosine phosphorylation of Stat3. Dissociation of Fer and Jak1, as well as elevation in the level of Fer and in the tyrosine phosphorylation of Stat3, depended on the activity of phosphatidylinositol 3-kinase (PI3K) and was abolished by a PI3K inhibitor. However, Fer and Stat3 were only mildly affected by low concentrations of IGF-I, another activator of the PI3K pathway that can also induce myogenic differentiation. RNA interference directed toward the fer mRNA did not affect the cellular levels of Stat3 but led to a dramatic reduction in the tyrosine phosphorylation level of this transcription factor. Thus, Fer is a downstream effector of insulin and mediates the activation of Stat3 in myogenic cells.