The cyclooxygenase-2 inhibitor celecoxib has therapeutic effects in major depression: results of a double-blind, randomized, placebo controlled, add-on pilot study to reboxetine

Sustained remission of rheumatoid arthritis with a specific serotonin reuptake inhibitor antidepressant: a case report and review of the literature

Introduction

The mainstay of pharmacologic therapy for rheumatoid arthritis includes the use of disease-modifying agents like sulfasalazine and methothrexate, and more recently, anti-tumor necrosis factor-α agents. Depression remains a major co-morbidity in patients with rheumatoid arthritis and is thought to contribute to disability and mortality in these patients. Evidence now suggests that a biologic link exists between substrates responsible for inflammatory conditions and mood disorders. Most of this evidence comes from preclinical studies. Nevertheless, more research into this area is helping us to understand the possible mechanisms through which these conditions interact with each other.

Case presentation

We describe a 60-year-old Indian man with rheumatoid arthritis diagnosed 15 years ago who had minimal response to multiple therapies with disease-modifying agents and whose arthritis symptoms surprisingly remitted when he was started on a specific serotonin reuptake inhibitor antidepressant, three years ago, for co-morbid major depression. This remission has been maintained with this medication, and the patient is currently not taking any antirheumatoid medications.

Conclusion

Possible mechanisms linking substrates of mood disorders and inflammation are reviewed in this case report, particularly the serotonergic system. Evidence seems to suggest a significant interaction between the serotonergic systems and inflammation. This interaction seems to be bidirectional. An understanding of this relation is most important to gain insight not only into pathophysiological mechanisms underlying this condition, but also into how treatments for these conditions may complement each other and possibly provide greater therapeutic options in both of these disabling conditions.

Hyperforin, an Anti-Inflammatory Constituent from St. John's Wort, Inhibits Microsomal Prostaglandin E(2) Synthase-1 and Suppresses Prostaglandin E(2) Formation in vivo

The acylphloroglucinol hyperforin (Hyp) from St. John's wort possesses anti-inflammatory and anti-carcinogenic properties which were ascribed among others to the inhibition of 5-lipoxygenase. Here, we investigated whether Hyp also interferes with prostanoid generation in biological systems, particularly with key enzymes participating in prostaglandin (PG)E₂ biosynthesis, i.e., cyclooxygenases (COX)-1/2 and microsomal PGE₂ synthase (mPGES)-1 which play key roles in inflammation and tumorigenesis. Similar to the mPGES-1 inhibitors MK-886 and MD-52, Hyp significantly suppressed PGE₂ formation in whole blood assays starting at 0.03–1 μM, whereas the concomitant generation of COX-derived 12(S)-hydroxy-5-cis-8,10-trans-heptadecatrienoic acid, thromboxane B₂, and 6-keto PGF_1α was not significantly suppressed up to 30 μM. In cell-free assays, Hyp efficiently blocked the conversion of PGH₂ to PGE₂ mediated by mPGES-1 (IC₅₀ = 1 μM), and isolated COX enzymes were not (COX-2) or hardly (COX-1) suppressed. Intraperitoneal (i.p.) administration of Hyp (4 mg kg⁻¹) to rats impaired exudate volume and leukocyte numbers in carrageenan-induced pleurisy associated with reduced PGE₂ levels, and Hyp (given i.p.) inhibited carrageenan-induced mouse paw edema formation (ED₅₀ = 1 mg kg⁻¹) being superior over indomethacin (ED₅₀ = 5 mg kg⁻¹). We conclude that the suppression of PGE₂ biosynthesis in vitro and in vivo by acting on mPGES-1 critically contributes to the anti-inflammatory efficiency of Hyp.

Immune system to brain signaling: neuropsychopharmacological implications

There has been an explosion in our knowledge of the pathways and mechanisms by which the immune system can influence the brain and behavior. In the context of inflammation, pro-inflammatory cytokines can access the central nervous system and interact with a cytokine network in the brain to influence virtually every aspect of brain function relevant to behavior including neurotransmitter metabolism, neuroendocrine function, synaptic plasticity, and neurocircuits that regulate mood, motor activity, motivation, anxiety and alarm. Behavioral consequences of these effects of the immune system on the brain include depression, anxiety, fatigue, psychomotor slowing, anorexia, cognitive dysfunction and sleep impairment; symptoms that overlap with those which characterize neuropsychiatric disorders, especially depression. Pathways that appear to be especially important in immune system effects on the brain include the cytokine signaling molecules, p38 mitogen-activated protein kinase and nuclear factor kappa B; indoleamine 2,3 dioxygenase and its downstream metabolites, kynurenine, quinolinic acid and kynurenic acid; the neurotransmitters, serotonin, dopamine and glutamate; and neurocircuits involving the basal ganglia and anterior cingulate cortex. A series of vulnerability factors including aging and obesity as well as chronic stress also appears to interact with immune to brain signaling to exacerbate immunologic contributions to neuropsychiatric disease. The elucidation of the mechanisms by which the immune system influences behavior yields a host of targets for potential therapeutic development as well as informing strategies for the prevention of neuropsychiatric disease in at risk populations.

Immune suppression and immune activation in depression

Depression has been characterized as a disorder of both immune suppression and immune activation. Markers of impaired cellular immunity (decreased natural killer cell cytotoxicity) and inflammation (elevated IL-6, TNFα, and CRP) have been associated with depression. These immunological markers have been associated with other medical illnesses, suggesting that immune dysregulation may be a central feature common to both depression and to its frequent medical comorbidities. Yet the significant associations of findings of both immune suppression and immune activation with depression raise questions concerning the relationship between these two classes of immunological observations. Depressed populations are heterogeneous groups, and there may be differences in the immune profiles of populations that are more narrowly defined in terms of symptom profile and/or demographic features. There have been few reports concurrently investigating markers of immune suppression and immune activation in the same depressed individuals. An emerging pre-clinical literature suggests that chronic inflammation may directly contribute to the pathophysiology of immune suppression in the context of illnesses such as cancer and rheumatoid arthritis. This literature provides us with specific immunoregulatory mechanisms mediating these relationships that could also explain differences in immune disturbances between subsets of depressed individuals We propose a research agenda emphasizing the assessment of these immunoregulatory mechanisms in large samples of depressed subjects as a means to define the relationships among immune findings (suppression and/or activation) within the same depressed individuals and to characterize subsets of depressed subjects based on shared immune profiles. Such a program of research, building on and integrating our knowledge of the psychoneuroimmunology of depression, could lead to innovation in the assessment and treatment of depression and its medical comorbidities.

Depression: a repair response to stress-induced neuronal microdamage that can grade into a chronic neuroinflammatory condition?

Depression is a major contributor to the global burden of disease and disability, yet it is poorly understood. Here we review data supporting a novel theoretical model for the biology of depression. In this model, a stressful life event leads to microdamage in the brain. This damage triggers an injury repair response consisting of a neuroinflammatory phase to clear cellular debris and a spontaneous tissue regeneration phase involving neurotrophins and neurogenesis. During healing, released inflammatory mediators trigger sickness behavior and psychological pain via mechanisms similar to those that produce physical pain during wound healing. The depression remits if the neuronal injury repair process resolves successfully. Importantly, however, the acute psychological pain and neuroinflammation often transition to chronicity and develop into pathological depressive states. This hypothesis for depression explains substantially more data than alternative models, including why emerging data show that analgesic, anti-inflammatory, pro-neurogenic and pro-neurotrophic treatments have antidepressant effects. Thus, an acute depressive episode can be conceptualized as a normally self-limiting but highly error-prone process of recuperation from stress-triggered neuronal microdamage.

A biological pathway linking inflammation and depression: activation of indoleamine 2,3-dioxygenase

This article highlights the evidence linking depression to increased inflammatory drive and explores putative mechanisms for the association by reviewing both preclinical and clinical literature. The enzyme indoleamine 2,3-dioxygenase is induced by proinflammatory cytokines and may form a link between immune functioning and altered neurotransmission, which results in depression. Increased indoleamine 2,3-dioxygenase activity may cause both tryptophan depletion and increased neurotoxic metabolites of the kynurenine pathway, two alterations which have been hypothesized to cause depression. The tryptophan-kynurenine pathway is comprehensively described with a focus on the evidence linking metabolite alterations to depression. The use of immune-activated groups at high risk of depression have been used to explore these hypotheses; we focus on the studies involving chronic hepatitis C patients receiving interferon-alpha, an immune activating cytokine. Findings from this work have led to novel strategies for the future development of antidepressants including inhibition of indoleamine 2,3-dioxygenase, moderating the cytokines which activate it, or addressing other targets in the kynurenine pathway.

Sustained elevation of serum interleukin-6 and relative insensitivity to hydrocortisone differentiates posttraumatic stress disorder with and without depression

BACKGROUND

Elevated levels of proinflammatory cytokines, especially interleukin-6 (IL-6), can mediate the greater risk for cardiovascular disease in individuals with posttraumatic stress disorder (PTSD), particularly in those with comorbid major depressive disorder (MDD). However, IL-6 levels are not consistently elevated in either PTSD or MDD. Although PTSD is associated with supersensitivity to glucocorticoids; prior studies have not evaluated the effect of comorbid MDD.

METHODS

Serum IL-6 levels were measured hourly between 7:00 pm and 7:00 am in individuals with PTSD with comorbid MDD (PTSD + MDD) (n = 9) and compared with those with PTSD without MDD (PTSD - MDD) (n = 9) and nontraumatized healthy control subjects (n = 14). Group differences in serum IL-6, plasma adrenocorticotropic hormone (ACTH), and plasma cortisol response to 30 mg of intravenous hydrocortisone were evaluated using linear mixed models.

RESULTS

Only subjects with PTSD + MDD exhibited higher, overnight serum IL-6 levels compared with individuals with PTSD - MDD (p < .01) and healthy control subjects (p < .001). Peak overnight IL-6 levels positively correlated with severity of PTSD (r = .56, p < .01) and depressive symptoms (r = .54, p < .01). Hydrocortisone administration significantly reduced IL-6 levels in both PTSD groups; however, IL-6 levels in PTSD + MDD were higher than both PTSD - MDD (p < .05) and healthy control subjects (p < .01). Following hydrocortisone administration, there was a greater reduction in levels of ACTH in PTSD - MDD compared with control subjects (p < .01).

CONCLUSIONS

Sustained elevations of overnight IL-6 levels and relatively decreased sensitivity to hydrocortisone distinguish PTSD + MDD from PTSD - MDD. Novel strategies that decrease IL-6 levels offer a new direction in the prevention and treatment of PTSD and associated comorbid medical illnesses.

Chronic gastrointestinal inflammation induces anxiety-like behavior and alters central nervous system biochemistry in mice

BACKGROUND & AIMS

Clinical and preclinical studies have associated gastrointestinal inflammation and infection with altered behavior. We investigated whether chronic gut inflammation alters behavior and brain biochemistry and examined underlying mechanisms.

METHODS

AKR mice were infected with the noninvasive parasite Trichuris muris and given etanercept, budesonide, or specific probiotics. Subdiaphragmatic vagotomy was performed in a subgroup of mice before infection. Gastrointestinal inflammation was assessed by histology and quantification of myeloperoxidase activity. Serum proteins were measured by proteomic analysis, circulating cytokines were measured by fluorescence activated cell sorting array, and serum tryptophan and kynurenine were measured by liquid chromatography. Behavior was assessed using light/dark preference and step-down tests. In situ hybridization was used to assess brain-derived neurotrophic factor (BDNF) expression in the brain.

RESULTS

T muris caused mild to moderate colonic inflammation and anxiety-like behavior that was associated with decreased hippocampal BDNF messenger RNA (mRNA). Circulating tumor necrosis factor-α and interferon-γ, as well as the kynurenine and kynurenine/tryptophan ratio, were increased. Proteomic analysis showed altered levels of several proteins related to inflammation and neural function. Administration of etanercept, and to a lesser degree of budesonide, normalized behavior, reduced cytokine and kynurenine levels, but did not influence BDNF expression. The probiotic Bifidobacterium longum normalized behavior and BDNF mRNA but did not affect cytokine or kynurenine levels. Anxiety-like behavior was present in infected mice after vagotomy.

CONCLUSIONS

Chronic gastrointestinal inflammation induces anxiety-like behavior and alters central nervous system biochemistry, which can be normalized by inflammation-dependent and -independent mechanisms, neither of which requires the integrity of the vagus nerve.

Maintenance therapy of celecoxib for major depression with mimicking neuropsychological dysfunction

Growing evidence suggests that proinflammatory responses will be a crucial issue for developing neuropsychiatric disorders. Recent clinical trials demonstrated that adjunctive therapy of cyclo-oxygenase (COX)-2 inhibitor was effective for major depression. Here, we present the case of an elderly depressed woman with acute cognitive deficit who was refractory to multiple antidepressants but only responsive to celecoxib, a COX-2 inhibitor, in acute treatment and sustaining remission for a 5-year treatment course. Our finding suggests that a therapeutic effect of celecoxib exists for major depressive disorder comorbid with neurocognitive dysfunction.

Inflammatory gene expression in monocytes of patients with schizophrenia: overlap and difference with bipolar disorder. A study in naturalistically treated patients

Accumulating evidence indicates an activated inflammatory response system as a vulnerability factor for schizophrenia (SZ) and bipolar disorder (BD). We aimed to detect a specific inflammatory monocyte gene expression signature in SZ and compare such signature with our recently described inflammatory monocyte gene signature in BD. A quantitative-polymerase chain reaction (Q-PCR) case-control gene expression study was performed on monocytes of 27 SZ patients and compared to outcomes collected in 56 BD patients (all patients naturalistically treated). For Q-PCR we used nine 'SZ specific genes' (found in whole genome analysis), the 19 BD signature genes (previously found by us) and six recently described autoimmune diabetes inflammatory monocyte genes. Monocytes of SZ patients had (similar to those of BD patients) a high inflammatory set point composed of three subsets of strongly correlating genes characterized by different sets of transcription/MAPK regulating factors. Subset 1A, characterized by ATF3 and DUSP2, and subset 1B, characterized by EGR3 and MXD1, were shared between BD and SZ patients (up-regulated in 67% and 51%, and 34% and 41%, respectively). Subset 2, characterized by PTPN7 and NAB2 was up-regulated in the monocytes of 62% BD, but down-regulated in the monocytes of 48% of SZ patients. Our approach shows that monocytes of SZ and BD patients overlap, but also differ in inflammatory gene expression. Our approach opens new avenues for nosological classifications of psychoses based on the inflammatory state of patients, enabling selection of those patients who might benefit from an anti-inflammatory treatment.

Is there a role for the nuclear receptor PPARγ in neuropsychiatric diseases?

The aetiology of psychiatric diseases such as depression or schizophrenia remains largely unknown, even though multiple theories have been proposed. Although monoamine theory is the cornerstone of available pharmacological therapies, relapses, incomplete control of symptoms or failure in treatment occur frequently. From an inflammatory/immune point of view, both entities share several common hallmarks in their pathophysiology, e.g. neuroendocrine/immune alterations, structural/functional abnormalities in particular brain areas, and cognitive deficits, suggesting a dysregulated inflammatory-related component of these diseases that better explains the myriad of symptoms presented by affected individuals. In this review we aimed to explore the role and relevance of inflammatory related lipids (prostanoids) derived from arachidonic acid metabolism by identification of new inflammatory markers and possible pharmacological/dietary modulation of these compounds, with the aim of improving some of the symptoms developed by individuals affected with psychiatric diseases (a critical review of basic and clinical studies about inflammatory-related arachidonic acid metabolism on neuropsychiatric diseases is included). As a specific candidate, one of these immunoregulatory lipids, the anti-inflammatory prostaglandin 15d-PGJ₂ and its nuclear receptor peroxisome proliferator-activated nuclear receptor (PPARγ) could be used as a biological marker for psychiatric diseases. In addition, its pharmacological activation can be considered as a multi-faceted therapeutic target due to its anti-inflammatory/antioxidant/anti-excitotoxic/pro-energetic profile, reported in some inflammatory-related scenarios (neurological and stress-related diseases). PPARs are activated by a great variety of compounds, the most relevant being the currently prescribed group of anti-diabetic drugs thiazolidinediones, and some cannabinoids (both endocannabinoids, phytocannabinoids or synthetic), as possible novel therapeutical strategy.

Neuroimmune pharmacology of neurodegenerative and mental diseases

Neuroimmune pharmacology is a newly emerging field that intersects with neuroscience, immunology, and pharmacology and that is seeking avenues for translational research and better understanding of disease mechanisms. It focuses on the immunity of the central nervous system (CNS) which is greatly influenced by endogenous effectors, such as cytokines and neurotransmitters, and by exogenous substances, including therapeutic compounds, infectious pathogens, and drugs of abuse. In this article, we attempt to raise awareness of the pivotal discovery of how those mediators affect the immunity of the CNS in both physiological conditions and processes of certain mental illnesses, including psychiatric disorders, neurodegenerative diseases, and cerebral dysfunctions due to drugs of abuse. The abnormality in cytokine networks, neurotransmitter homeostasis, and other immune responses may be involved in the neuropathology associated with those mental illnesses, and the therapeutic effects of the potential treatments can be attributed, at least partially, to their immunomodulatory activities. However, the resulting inflammatory cytokines from certain treatments frequently cause psychiatric complications. In addition, the poor neuropathological outcomes frequently found among drug abusers with HIV-1 infection appear to be related to the neurotoxic and immunomodulatory effects of the drugs used. Importantly, glial cells, especially microglia and astrocytes, are key players in the immunomodulatory activities in the CNS, and the functioning CNS is largely dependent upon the reciprocal interactions between neurons and glial cells. Therefore, glia-neuron interactions have become a critical issue for further understanding the disease mechanism. From this review, readers will gain insights into the new field of neuroimmune pharmacology, with a focus on the impacts of CNS immunity on the mental illnesses.

Celecoxib treatment in an early stage of schizophrenia: results of a randomized, double-blind, placebo-controlled trial of celecoxib augmentation of amisulpride treatment

Recent trials support the hypothesis of the role of inflammation in the pathogenesis of schizophrenia. The overall therapeutic benefit of anti-inflammatory medication, in particular cyclo-oxygenase-2 (COX-2) inhibitors in schizophrenia, is still controversial. There are suggestions that therapy with COX-2 inhibitors may influence the early stages of the disease. Taking these findings into account, we conducted a double-blind, placebo-controlled, randomized trial of celecoxib augmentation to amisulpride treatment in patients with a first manifestation of schizophrenia. Forty-nine patients diagnosed with schizophrenia were randomly assigned. They were treated either with amisulpride (200-1000 mg) plus celecoxib (400 mg) or amisulpride (200-1000 mg) plus placebo. Inclusion criterion was the diagnosis of schizophrenia during the past two years according to DSM-IV. The trial lasted six weeks. At weekly intervals an assessment of the psychopathology was performed using the Positive and Negative Symptom Scale (PANSS) and the Global Clinical Impression Scale (CGI). A significantly better outcome was observed in the patient group treated with amisulpride plus celecoxib compared to the group with amisulpride plus placebo (PANSS negative: p=0.03; PANSS global; p=0.05 and PANSS total: p=0.02). In addition, ratings by the CGI scale during therapy with amisulpride and celecoxib showed a significantly better result (p< or =0.001). A significantly superior therapeutic effect could be observed in the celecoxib group compared to placebo in the treatment of early stage schizophrenia. This is the first time an improvement in patients' negative symptoms has been demonstrated with celecoxib. In future, further trials are needed to investigate the effect of COX-2 inhibitors on prodromal and negative symptoms of schizophrenia.

Eating ourselves to death (and despair): the contribution of adiposity and inflammation to depression

Obesity and related metabolic conditions are of epidemic proportions in most of the world, affecting both adults and children. The accumulation of lipids in the body in the form of white adipose tissue in the abdomen is now known to activate innate immune mechanisms. Lipid accumulation causes adipocytes to directly secrete the cytokines interleukin (IL) 6 and tumor necrosis factor alpha (TNFalpha), but also monocyte chemoattractant protein 1 (MCP-1), which results in the accumulation of leukocytes in fat tissue. This sets up a chronic inflammatory state which is known to mediate the association between obesity and conditions such as cardiovascular disease, type 2 diabetes, and cancer. There is also a substantial literature linking inflammation with risk for depression. This includes the observations that: (1) people with inflammatory diseases such as multiple sclerosis, cardiovascular disease, and psoriasis have elevated rates of depression; (2) many people administered inflammatory cytokines such as interferon alpha develop depression that is indistinguishable from depression in non-medically ill populations; (3) a significant proportion of depressed persons show upregulation of inflammatory factors such as IL-6, C-reactive protein, and TNFalpha; (4) inflammatory cytokines can interact with virtually every pathophysiologic domain relevant to depression, including neurotransmitter metabolism, neuroendocrine function, and synaptic plasticity. While many factors may contribute to the association between inflammatory mediators and depression, we hypothesize that increased adiposity may be one causal pathway. Mediational analysis suggests a bi-directional association between adiposity and depression, with inflammation possibly playing an intermediary role.

The concept of depression as a dysfunction of the immune system

Chronic stress, by initiating changes in the hypothalamic-pituitary-adrenal axis and the immune system, acts as a trigger for anxiety and depression. Both experimental and clinical evidence shows that a rise in the concentrations of proinflammatory cytokines and glucocorticoids, as occurs in chronically stressful situations and in depression, contribute to the behavioural changes associated with depression.A defect in serotonergic function is associated with hypercortisolaemia and the increase in proinflammatory cytokines that accompany depression. Glucocorticoids and proinflammatory cytokines enhance the conversion of tryptophan to kynurenine. In addition to the resulting decrease in the synthesis of brain serotonin, this leads to the formation of neurotoxins such as the glutamate agonist quinolinic acid and contributes to the increase in apoptosis of astrocytes, oligodendroglia and neurons.The importance of the inflammation hypothesis of depression lies in raising the possibility that psychotropic drugs that have a central anti-inflammatory action might provide a new generation of antidepressants.

Inflammatory biomarkers and depression

Antidepressants, predominantly serotonin- and/or noradrenaline reuptake inhibiting drugs have several shortcomings. The exact pathophysiological mechanisms leading to serotonergic-, noradrenergic- or dopaminergic dysfunction are still unclear. An inflammatory mechanism has been postulated and will be discussed here including possible therapeutic advantages of cyclooxygenase-2 (COX-2) inhibitors. Differences in the activation of the enzyme indoleamine 2,3-dioxygenase (IDO) and in the tryptophan-kynurenine metabolism resulting in an increased tryptophan and serotonin degradation and probably in an increased production of quinolinic acid might play a key role in major depression (MD). These differences are associated with an imbalance in the glutamatergic neurotransmission, which may contribute to an overweight of N-methyl-D: -aspartate agonism in MD. The immunological imbalance results in an increased prostaglandin E₂ production and probably also in an increased COX-2 expression. Although there is strong evidence for the view that the interactions of the immune system, IDO, the serotonergic system and the glutamatergic neurotransmission play a key role in MD, several gaps, e.g. the roles of genetics, disease course, sex, different psychopathological states, etc., have to be bridged by intense further research. There were already hints that anti-inflammatory therapy might have beneficial effects in MD. COX-2 inhibitors, however, have been tested in animal models and in preliminary clinical studies showing favourable effects compared to placebo in MD. The effects of COX-2 inhibition in the CNS as well as the different components of the inflammatory system, the kynurenine-metabolism and the glutamatergic neurotransmission, however, still need careful further scientific evaluation including clinical studies in bigger samples of patients.

Antidepressant pharmacotherapy: focus on sex differences in neuroimmunopharmacological crossroads

Major depression is a stress-related disorder that shows a clear female preponderance. Sex differences in antidepressant response have been documented in both the clinical and experimental settings. It is of interest that antidepressant drugs exert critical immunotropic influences, mediated by direct and/or compensatory routes; these effects are not completely understood but comprise a matter of intensive investigation. Even though human studies have found only a few sex-related differences in the immunotropic effects of antidepressants, recent experimental evidence in the chronic mild stress model of depression points towards a sexually dimorphic neuroimmune playground in view of chronic antidepressant treatment. Herein, we provide a concise review regarding the effects of antidepressant pharmacotherapy on neuroimmune manifestations by concentrating on intriguing sex differences.

Antidepressants, but not antipsychotics, modulate GR function in human whole blood: an insight into molecular mechanisms

Clinical studies have demonstrated an impairment of glucocorticoid receptor (GR)-mediated negative feedback on the hypothalamic-pituitary-adrenal (HPA) axis in patients with major depression (GR resistance), and its resolution by antidepressant treatment. Recently, we showed that this impairment is indeed due to a dysfunction of GR in depressed patients (Carvalho et al., 2009), and that the ability of the antidepressant clomipramine to decrease GR function in peripheral blood cells is impaired in patients with major depression who are clinically resistant to treatment (Carvalho et al. 2008). To further investigate the effect of antidepressants on GR function in humans, we have compared the effect of the antidepressants clomipramine, amytriptiline, sertraline, paroxetine and venlafaxine, and of the antipsychotics, haloperidol and risperidone, on GR function in peripheral blood cells from healthy volunteers (n=33). GR function was measured by glucocorticoid inhibition of lypopolysaccharide (LPS)-stimulated interleukin-6 (IL-6) levels. Compared to vehicle-treated cells, all antidepressants inhibited dexamethasone (DEX, 10-100nM) inhibition of LPS-stimulated IL-6 levels (p values ranging from 0.007 to 0.1). This effect was specific to antidepressants, as antipsychotics had no effect on DEX-inhibition of LPS-stimulated IL-6 levels. The phosphodiesterase (PDE) type 4 inhibitor, rolipram, potentiated the effect of antidepressants on GR function, while the GR antagonist, RU-486, inhibited the effect of antidepressants on GR function. These findings indicate that the effect of antidepressants on GR function are specific for this class of psychotropic drugs, and involve second messenger pathways relevant to GR function and inflammation. Furthermore, it also points towards a possible mechanism by which one maybe able to overcome treatment-resistant depression. Research in this field will lead to new insights into the pathophysiology and treatment of affective disorders.

Sex-dependent effects of neonatal inflammation on adult inflammatory markers and behavior

Inflammatory molecules, such as cyclooxygenase (COX), a prostaglandin synthetic enzyme, have been identified as a marker of depressive symptomology. Previously, we have observed elevated basal COX-2 expression in the hypothalamus of adult male rats treated neonatally with lipopolysaccharide (LPS), which might suggest a phenotype for disrupted hedonic behavior, a symptom of depression. However, COX-2 and its contribution to the expression of anhedonic behavior has not been investigated in these males or in female rats across the estrous cycle, which is the purpose of the current work. Here, we examine the effects of a neonatal LPS challenge or saline on the sucrose preference test as a measure of anhedonia, and hypothalamic COX-2 expression, in adult male and freely cycling female rats. Our data indicate a sex difference in that neonatal LPS at postnatal d 14 causes elevated basal expression of hypothalamic COX-2 in male, but not in female, rats. Additionally, baseline sucrose preference in male and female rats was unaltered as a function of neonatal LPS treatment or estrous cycle stage. In both male and female animals, 50 microg/kg LPS in adulthood caused elevated plasma IL-6 and hypothalamic COX-2 expression in neonatally saline-treated rats but significantly less so in neonatally LPS-treated rats of both sexes; this neonatal programming was not evident for sucrose preference or for total fluid intake (even after much higher doses of LPS). Our data are suggestive of a dissociation between inflammation and anhedonic behavior and a differential effect of neonatal inflammation in males and females.

Insulin resistance, obesity, inflammation, and depression in polycystic ovary syndrome: biobehavioral mechanisms and interventions

OBJECTIVE

To summarize physiological and psychological characteristics that are common among women diagnosed with polycystic ovary syndrome (PCOS) and provide evidence suggesting that addressing psychological disturbances can reduce or alleviate physical symptoms of PCOS through behavioral pathways and physiological pathways.

METHOD(S)

Empirical studies and expert consensuses pertaining to physiological, psychological, and medical management aspects of PCOS were identified and presented in this review. Articles were identified by searching Pubmed, PsycInfo, Medline ISI, CINAHL, or a Web browser (i.e., Google) using numerous combinations of terms pertaining to physiological, psychological, and medical management aspects of PCOS. An article was chosen to be included in this review if it reported findings and/or provided information that related to and helped support the main purpose(s) of this review article.

RESULT(S)

Available literature on the physiological (i.e., hyperandrogenism, central obesity, inflammation, insulin resistance) and psychological (i.e., depression, anxiety, eating disorders) factors among women with PCOS provides evidence that these various aspects of PCOS are strongly interrelated.

CONCLUSION(S)

The existence of these relationships among physiological and psychological factors strongly suggests that medical management of PCOS would greatly benefit from inclusion of psychological and behavioral approaches.

Linking the cytokine and neurocircuitry hypotheses of depression: a translational framework for discovery and development of novel anti-depressants

Recent studies suggest a model of depression that links the cytokine hypothesis from the field of psychoneuroimmunology with the neurocircuitry hypothesis derived from burgeoning insight into neurophysiological changes observed in depressed patients. According to the neurocircuitry hypothesis of depression, failure of homeostatic synaptic plasticity in cortical-striatal-limbic nodes of a distributed network of neural circuits involving the sub-genual anterior cingulate cortex is responsible for core symptoms of depression: loss of interest or pleasure (anhedonia) and depressed mood (sadness). According to the cytokine hypothesis of depression, inflammatory cytokines act on neural circuits to evoke the behavioral and physiological changes observed in depression. Synthesis of these hypotheses implicates cytokines released during injury, infection, illness, or psychological stress as a cause of dysregulated synaptic plasticity in cortical-striatal-limbic circuits implicated in depression. These neural circuits process affective and reward-based information for optimal cost-benefit decision-making, a function that may link cytokine-evoked changes in synaptic plasticity to translatable measures of specific behavioral impairments observed in depressed patients. This viewpoint outlines evidence linking the cytokine and neurocircuitry hypotheses of depression to offer a translational model of major depressive disorder suitable for novel drug discovery and development.

CSF concentrations of brain tryptophan and kynurenines during immune stimulation with IFN-alpha: relationship to CNS immune responses and depression

Cytokine-induced activation of indoleamine 2,3-dioxygenase (IDO) catabolizes L-tryptophan (TRP) into L-kynurenine (KYN), which is metabolized to quinolinic acid (QUIN) and kynurenic acid (KA). QUIN and KA are neuroactive and may contribute to the behavioral changes experienced by some patients during exposure to inflammatory stimuli such as interferon (IFN)-alpha. A relationship between depressive symptoms and peripheral blood TRP, KYN and KA during treatment with IFN-alpha has been described. However, whether peripheral blood changes in these IDO catabolites are manifest in the brain and whether they are related to central nervous system cytokine responses and/or behavior is unknown. Accordingly, TRP, KYN, QUIN and KA were measured in cerebrospinal fluid (CSF) and blood along with CSF concentrations of relevant cytokines, chemokines and soluble cytokine receptors in 27 patients with hepatitis C after approximately 12 weeks of either treatment with IFN-alpha (n=16) or no treatment (n=11). Depressive symptoms were assessed using the Montgomery-Asberg Depression Rating Scale. IFN-alpha significantly increased peripheral blood KYN, which was accompanied by marked increases in CSF KYN. Increased CSF KYN was in turn associated with significant increases in CSF QUIN and KA. Despite significant decreases in peripheral blood TRP, IFN-alpha had no effect on CSF TRP concentrations. Increases in CSF KYN and QUIN were correlated with increased CSF IFN-alpha, soluble tumor necrosis factor-alpha receptor 2 and monocyte chemoattractant protein-1 as well as increased depressive symptoms. In conclusion, peripheral administration of IFN-alpha activated IDO in concert with central cytokine responses, resulting in increased brain KYN and QUIN, which correlated with depressive symptoms.

Cerebrospinal fluid analysis in affective and schizophrenic spectrum disorders: identification of subgroups with immune responses and blood-CSF barrier dysfunction

Immune and inflammatory mechanisms are detected in a subgroup of treatment resistant hospitalized affective and schizophrenic spectrum disorder patients. We analysed albumin, IgG, IgA, IgM, oligoclonal IgG and specific antibodies in paired cerebrospinal fluid (CSF) and serum samples. Numerical and graphical interpretation of CSF protein data was performed by Reibergrams with a new CSF statistics tool for nonlinear group analysis with reference to a large control group (n=4100). In 41% of the psychiatric patients (n=63) we observed CSF pathologies: 14% displayed intrathecal humoral immune responses, 10% slightly increased CSF cell counts (5-8/microL) and 29% had moderate blood-CSF barrier dysfunctions, in 24% as the only pathological sign with normal IgG, IgA and IgM concentrations in CSF (p=0.9 testing the null hypothesis for intrathecal synthesis with reference to Qmean of the reference group). In the group of affective (n=24) spectrum disorders 20% displayed a systemic immune reaction as detected by oligoclonal IgG. CSF analysis and interdisciplinary clinical approach revealed 6% of psychiatric patients likely to represent a virusspecific, bacterial or autoimmune associated disorder with CNS involvement. Elevated CSF neopterin concentration in 34% of the patients was interpreted as an increased release from astrocytes or from other glia cells. The low level immune response and barrier dysfunctions are discussed on the base of a mild encephalitis pathomechanism in subgroups of psychiatric patients. CSF analysis is shown to be a useful diagnostic tool for differential diagnosis in psychiatric diseases.

Interferon-gamma deficiency modifies the effects of a chronic stressor in mice: Implications for psychological pathology

Pro-inflammatory cytokines promote behavioral and neurochemical variations similar to those evident following stressor exposure, and have been implicated in promoting depressive illness. Indeed, immunotherapeutic application of the cytokine, interferon-alpha, promoted depressive illness in cancer and hepatitis C patients. We assessed the possibility that another interferon cytokine family member, interferon-gamma (IFN-gamma), might contribute to the behavioral and biochemical alterations provoked by a chronic stressor regimen that has been used to model neuropsychiatric pathology in rodents. As predicted, IFN-gamma-deficient mice displayed basal differences in behavior (e.g., reduced open field exploration) and altered neurochemical activity (e.g., increased noradrenergic and serotonergic activity within the central amygdala), relative to their wild-type counterparts. Moreover, stressor-induced elevations of corticosterone and the pro-inflammatory cytokine, tumor necrosis factor-alpha, were attenuated in IFN-gamma-deficient mice. Similarly, the IFN-gamma null mice were refractory to the chronic stressor-induced alterations of dopamine metabolism (within the prefrontal cortex, paraventricular nucleus of the hypothalamus and central amygdala) evident in wild-type mice. Yet, the chronic stressor provoked signs of anxiety (e.g., reduced open field exploration) and depression-like behavior (e.g., increased forced swim immobility, reduced consumption of a palatable solution) among both wild-type and IFN-gamma knockout mice alike, suggesting a dissociation of behavioral functioning from the stressor-induced alterations of immunological, hormonal and dopaminergic activity. Together, these data suggest a complex neurobehavioral phenotype, wherein IFN-gamma deletion engenders a state of heightened basal emotionality coupled with increased monoaminergic activity in the amygdala. At the same time, however, IFN-gamma deficiency appears to blunt some of the neurochemical, corticoid and cytokine alterations ordinarily associated with chronic stressor exposure.

A meta-analysis of cytokines in major depression

BACKGROUND

Major depression occurs in 4.4% to 20% of the general population. Studies suggest that major depression is accompanied by immune dysregulation and activation of the inflammatory response system (IRS). Our objective was to quantitatively summarize the data on concentrations of specific cytokines in patients diagnosed with a major depressive episode and controls.

METHODS

We performed a meta-analysis of studies measuring cytokine concentration in patients with major depression, with a database search of the English literature (to August 2009) and a manual search of references.

RESULTS

Twenty-four studies involving unstimulated measurements of cytokines in patients meeting DSM criteria for major depression were included in the meta-analysis; 13 for tumor necrosis factor (TNF)-alpha, 9 for interleukin (IL)-1beta, 16 for IL-6, 5 for IL-4, 5 for IL-2, 4 for IL-8, 6 for IL-10, and 4 for interferon (IFN)-gamma. There were significantly higher concentrations of TNF-alpha (p < .00001), weighted mean difference (WMD) (95% confidence interval) 3.97 pg/mL (2.24 to 5.71), in depressed subjects compared with control subjects (438 depressed/350 nondepressed). Also, IL-6 concentrations were significantly higher (p < .00001) in depressed subjects compared with control subjects (492 depressed/400 nondepressed) with an overall WMD of 1.78 pg/mL (1.23 to 2.33). There were no significant differences among depressed and nondepressed subjects for the other cytokines studied.

CONCLUSIONS

This meta-analysis reports significantly higher concentrations of the proinflammatory cytokines TNF-alpha and IL-6 in depressed subjects compared with control subjects. While both positive and negative results have been reported in individual studies, this meta-analytic result strengthens evidence that depression is accompanied by activation of the IRS.

Pro-inflammatory biomakers in depression: treatment with venlafaxine

High levels of pro-inflammatory biomarkers have been reported in depression. In the present study, five pro-inflammatory biomarkers were measured in the blood of patients with major depressive disorder (MDD). Biomarker levels were compared to age- and sex-matched healthy subjects. Patients with MDD had significantly higher baseline levels of tumour necrosis factor-alpha (TNFalpha, P=0.04), interleukin-1beta (IL1beta, P=0.03), and monocyte chemotactic protein-1 (MCP-1; P=0.02) compared to controls. There were no differences between groups in levels of cell determinant-40 ligand (CD40L) and C-reactive protein (CRP). A subset of the MDD patients consented to undergo treatment with venlafaxine (an SNRI: at lower doses a selective serotonin reuptake inhibitor; at higher doses also a norepinephrine reuptake inhibitor) for 8 weeks. By week 8, all treatment completers had responded therapeutically. However, levels of TNFalpha, IL1beta, and MCP-1 remained elevated. A concave quadratic equation described the associations between plasma venlafaxine concentrations and IL1beta (P=0.03), TNFalpha (P=0.09), and MCP-1 (P=0.02), suggesting that these biomarkers may have become selectively lowered in the serotonergic dose range of venlafaxine. This is the first report of venlafaxine's possible effect on pro-inflammatory biomarkers.

Depression and immunity: a role for T cells?

Much attention has been paid to the potential role of the immune system in the pathophysiology of major depression in humans. While activation of innate immune responses currently dominates the research landscape, early studies in depressed patients demonstrating impairment in acquired immune responses, in particular T cell responses, may warrant further consideration. Intriguing data suggest that activated T cells may play an important neuroprotective role in the context of both stress and inflammation. For example, generation of autoreactive T cells through immunization with central nervous system (CNS) specific antigens has been shown to reverse stress-induced decreases in hippocampal neurogenesis as well as depressive-like behavior in rodents. In addition, trafficking of T cells to the brain following stress, in part related to glucocorticoids, has been found to reduce stress-induced anxiety-like behavior. Data indicate that T regulatory cells may also play a role in depression through downregulation of chronic inflammatory responses. Based on the notion that T cells may subserve neuroprotective and anti-inflammatory functions during stress and inflammation, impaired T cell function may directly contribute to the development of depression. Indeed, increased sensitivity to apoptosis as well as reduced responsiveness to glucocorticoids, may not only decrease the availability of T cells in depressed patients, but also may reduce their capacity to traffic to the brain in response to relevant neuroendocrine or immune stimuli. Further elucidation of T cell pathology may lead to new insights into immune system contributions to depression. Moreover, enhancement of T cell function may represent an alternative strategy to treat depression.

Potential novel therapeutics for bipolar disorders

Existing pharmacological treatments for bipolar disorder (BPD), a severe recurrent mood disorder, are in general insufficient for many patients. Despite adequate doses and treatment duration, many individuals with this disease continue to experience mood episode relapses, residual symptoms, and functional impairment. This chapter reviews a number of targets/compounds that could result in putative novel treatments for BPD, including the dynorphin opioid neuropeptide system, the glutamatergic system, the purinergic system, the cholinergic system (muscarinic and nicotinic systems), the oxidative stress system, and the melatonergic system. The arachidonic acid cascade and intracellular signaling cascades (including glycogen synthase kinase 3 and protein kinase C) are also reviewed, as are agents that affect multiple targets (e.g., modafinil, Uridine RG2417). Further study of these and similar agents may improve our understanding of relevant drug targets and their clinical utility as potential therapeutics for this devastating disorder.

Clinical trial of adjunctive celecoxib treatment in patients with major depression: a double blind and placebo controlled trial

BACKGROUND

The pathophysiology of depression is associated with the hyperactivity of immune inflammatory responses. Cyclooxygenase-2 inhibitors such as celecoxib reduce the production of pro-inflammatory cytokines. The purpose of the present investigation was to assess the efficacy of celecoxib as an adjuvant agent in the treatment of major depression in a six-week double blind and placebo controlled trial.

METHODS

Forty adult outpatients who met the DSM-IV-TR criteria for major depression participated in the trial. Patients have a baseline Hamilton Rating Scale for Depression score of at least 18. Patients were allocated in a random fashion: 20 to fluoxetine 40 mg/day plus celecoxib 400 mg/day (200 mg bid) (morning and evening) and 20 to fluoxetine 40 mg/day plus placebo. Patients were assessed by a psychiatrist at baseline and after 1, 2, 4, and 6 weeks after the medication started.

RESULTS

Although both protocols significantly decreased the score of Hamilton Rating Scale for Depression over the trial period, the combination of fluoxetine and celecoxib showed a significant superiority over fluoxetine alone in the treatment of symptoms of major depression. There were no significant differences in the two groups in terms of observed side effects.

CONCLUSION

The results of this study suggest that celecoxib may be an effective adjuvant agent in the management of patients with major depression and anti-inflammatory therapies should be further investigated.

Cytokines and glucocorticoid receptor signaling. Relevance to major depression

Data suggest that the activation of immune responses and the release of inflammatory cytokines may play a role in the pathophysiology of major depression. One mechanism by which cytokines may contribute to depression is through their effects on the glucocorticoid receptor (GR). Altered GR function in depression has been demonstrated by neuroendocrine challenge tests that reliably reveal reduced GR sensitivity as manifested by nonsuppression of cortisol following dexamethasone administration in vivo and lack of immune suppression following administration of glucocorticoids in vitro. Relevant to the GR, cytokines have been shown to decrease GR expression, block translocation of the GR from cytoplasm to nucleus, and disrupt GR-DNA binding through nuclear protein-protein interactions. In addition, cytokines have been shown to increase the expression of the relatively inert GR beta isoform. Specific cytokine signaling molecules that have been shown to be involved in the disruption of GR activity include p38 mitogen-activated protein kinase, which is associated with reduced GR translocation, and signal transducer and activator of transcription (STAT)5, which binds to GR in the nucleus. Nuclear factor-kappaB (NF-kappaB) also has been shown to lead to GR suppression through mutually inhibitory GR-NF-kappaB nuclear interactions. Interestingly, several antidepressants have been shown to enhance GR function, as has activation of protein kinase A (PKA). Antidepressants and PKA activation have also been found to inhibit inflammatory cytokines and their signaling pathways, suggesting that drugs that target both inflammatory responses and the GR may have special efficacy in the treatment of depression.

Does cytokine-induced depression differ from idiopathic major depression in medically healthy individuals?

BACKGROUND

Cytokines of the innate immune response may contribute to behavioral alterations that resemble major depression as manifested in medically healthy individuals.

METHODS

To explore potential similarities and differences between cytokine-induced depression and idiopathic major depression in healthy subjects, dimensional analyses comparing specific symptom dimensions of depression were conducted in 20 patients with malignant melanoma administered the innate immune cytokine, interferon (IFN)-alpha, and 28 medically healthy subjects with major depression of similar age and gender distribution. The Hamilton Rating Scale for Depression was used to assess severity of individual depressive symptoms.

RESULTS

Severity of symptoms of anxiety, depressed mood, and impaired work/activities were comparable between patients with IFN-alpha-induced depression and medically healthy depressed patients. Interestingly, however, compared to medically healthy patients with major depression, patients with IFN-alpha-induced depression reported significantly greater psychomotor retardation and weight loss and significantly less severe feelings of guilt.

LIMITATIONS

The relatively small sample size limited statistical power to detect small differences in symptom expression among groups.

CONCLUSIONS

The data suggest that there is considerable overlap in symptom expression between cytokine-induced depression and idiopathic depression in medically healthy subjects. Nevertheless, differences in isolated symptom domains suggest that cytokines may preferentially target neurocircuits relevant to psychomotor activity (e.g. basal ganglia), while having a limited effect on cognitive distortions regarding self-appraisal.

The impact of neuroimmune dysregulation on neuroprotection and neurotoxicity in psychiatric disorders--relation to drug treatment

An inflammatory pathogenesis has been postulated for schizophrenia and major depression (MD). In schizophrenia and depression, opposing patterns oftype-1 vs type-2 immune response seem to be associated with differences in the activation of the enzyme indoleamine 2,3-dioxygenase and in the tryptophan-kynurenine metabolism, resulting in increased production of kynurenic acid in schizophrenia and decreased production of kynurenic acid in depression. These differences are associated with an imbalance in the glutamatergic neurotransmission, which may contribute to an excessive agonist action of N-methyl-D-aspartate (NMDA) in depression and of NMDA antagonism in schizophrenia. Regarding the neuroprotective function of kynurenic acid and the neurotoxic effects of quinolinic acid (QUIN), different patterns of immune activation may also lead to an imbalance between the neuroprotective and the neurotoxic effects of the tryptophanlkynurenine metabolism. The differential activation of microglia cells and astrocytes may be an additional mechanism contributing to this imbalance. The immunological imbalance results in an inflammatory state combined with increased prostaglandin E2 production and increased cyclo-oxygenase-2 (COX-2) expression. The immunological effects of many existing antipsychotics and antidepressants, however, partly correct the immune imbalance and the excess production of the neurotoxic QUIN, COX-2 inhibitors have been tested in animal models of depression and in preliminary clinical trials, pointing to favorable effects in schizophrenia and in MD.

Spinal antinociceptive effects of cyclooxygenase inhibition during inflammation: Involvement of prostaglandins and endocannabinoids

Both cyclooxygenase-1 and -2 are expressed in the spinal cord, and the spinal COX product prostaglandin E(2) (PGE(2)) contributes to the generation of central sensitization upon peripheral inflammation. Vice versa spinal COX inhibition is considered an important mechanism of antihyperalgesic pain treatment. Recently, however, COX-2 was shown to be also involved in the metabolism of endocannabinoids. Because endocannabinoids can have analgesic actions it is conceivable that inhibition of spinal COX produces analgesia not only by inhibition of PG synthesis but also by inhibition of endocannabinoid breakdown. In the present study, we recorded from spinal cord neurons with input from the inflamed knee joint and we measured the spinal release of PGE(2) and the endocannabinoid 2-arachidonoyl glycerol (2-AG) in vivo, using the same stimulation procedures. COX inhibitors were applied spinally. Selective COX-1, selective COX-2 and non-selective COX inhibitors attenuated the generation of spinal hyperexcitability when applied before and during development of inflammation but, when inflammation and spinal hyperexcitability were established, only selective COX-2 inhibitors reversed spinal hyperexcitability. During established inflammation all COX inhibitors reduced release of spinal PGE(2) almost equally but only the COX-2 inhibitor prevented breakdown of 2-AG. The reversal of spinal hyperexcitability by COX-2 inhibitors was prevented or partially reversed by AM-251, an antagonist at the cannabinoid-1 receptor. We conclude that inhibition of spinal COX-2 not only reduces PG production but also endocannabinoid breakdown and provide evidence that reversal of inflammation-evoked spinal hyperexcitability by COX-2 inhibitors is more related to endocannabinoidergic mechanisms than to inhibition of spinal PG synthesis.

A prospective evaluation of the directionality of the depression-inflammation relationship

Cross-sectional studies have found that individuals with depressive disorders or symptoms have elevated levels of inflammatory markers predictive of coronary artery disease, including interleukin-6 (IL-6) and C-reactive protein (CRP). Due to the paucity of prospective studies, however, the directionality of the depression-inflammation relationship is unclear. We evaluated the longitudinal associations between depressive symptoms and both IL-6 and CRP among 263 healthy, older men and women enrolled in the Pittsburgh Healthy Heart Project, a 6-year prospective cohort study. During the baseline and follow-up visits, participants completed the Beck Depression Inventory-II (BDI-II) to assess depressive symptoms and underwent blood draws to quantify serum IL-6 and CRP. Path analyses revealed that baseline BDI-II (beta=0.18, p=0.01, DeltaR(2)=0.02) was a predictor of 6-year change in IL-6, even after adjustment for demographic, biomedical, and behavioral factors as well as other negative emotions. Of all the factors examined, only body-mass index was a stronger predictor of IL-6 change than depressive symptoms. In contrast to these results, baseline IL-6 did not predict 6-year change in BDI-II. Evidence of a weak bidirectional relationship between BDI-II and CRP was also observed; however, neither of these longitudinal associations was significant. The present findings indicate that depressive symptoms may precede and augment some inflammatory processes relevant to coronary artery disease among healthy, older adults. Therefore, our results imply that depression may lead to inflammation and that inflammation may be one of the mechanisms through which depression contributes to cardiovascular risk.

A critical review of human endotoxin administration as an experimental paradigm of depression

The syndrome called depression may represent the common final pathway at which different aetiopathogenic processes converge. One such aetiopathogenic process is innate immune system activation. Some depressed patients have increased levels of inflammatory cytokines and other immunologic abnormalities. It is not known whether immune system activation contributes to the pathogenesis of depressive symptoms. Supporting this possibility is the observation that in both rodents and humans, exogenous immune stimuli such as endotoxin can produce symptoms that resemble depression. A new approach to depression research would be to use immune stimuli to elicit depressive symptoms in humans. Here we review each of the symptoms elicited in humans by endotoxin administration, and compare this model to two other immune depression paradigms: interferon-alpha treatment and typhoid vaccine administration, to assess to what degree endotoxin administration represents a valid model of immune depression. We also review corresponding behavioral changes in rodents and the potential molecular pathways through which immune system activation produces each symptom.

Interleukin-6 is elevated in the cerebrospinal fluid of suicide attempters and related to symptom severity

BACKGROUND

Depressive disorders are associated with immune system alterations that can be detected in the blood. Cytokine concentrations in cerebrospinal fluid (CSF) and their relationship to aspects of suicidality have previously not been investigated.

METHODS

We measured interleukin-1beta, interleukin-6 (IL-6), interleukin-8, and tumor necrosis factor-alpha (TNF-alpha) in CSF and plasma of suicide attempters (n = 63) and healthy control subjects (n = 47). Patients were classified according to diagnosis and violent or nonviolent suicide attempt. We evaluated suicidal ideation and depressive symptoms using the Suicide Assessment Scale and the Montgomery-Asberg Depression Rating Scale (MADRS). We also analyzed the relation between cytokines and monoamine metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) in CSF, as well as the integrity of the blood-brain barrier as reflected by the CSF:serum albumin ratio.

RESULTS

IL-6 in CSF was significantly higher in suicide attempters than in healthy control subjects. Patients who performed violent suicide attempts displayed the highest IL-6. Furthermore, there was a significant positive correlation between MADRS scores and CSF IL-6 levels in all patients. IL-6 and TNF-alpha correlated significantly with 5-HIAA and HVA in CSF, but not with MHPG. Cytokine levels in plasma and CSF were not associated, and patients with increased blood-brain barrier permeability did not exhibit elevated cytokine levels.

CONCLUSIONS

We propose a role for CSF IL-6 in the symptomatology of suicidal behavior, possibly through mechanisms involving alterations of dopamine and serotonin metabolism.

Immunological and histochemical analyses of cerebrospinal fluid and peripheral blood from patients with neurological and psychiatric disorders

Epidemiological, clinical and post mortem studies indicate that inflammatory and immune reactions are involved in the pathomechanisms of affective and schizophrenic spectrum disorders. However, in psychiatric patients, only sporadic investigation on immunochemistry has been performed and information about immunofunction derived by investigation of immunocompetent cells in the CSF is not available to date. Here we present an interdisciplinary work of neurologists, psychiatrists and hemato-immunologists focusing on the immunology of psychiatric and neurological disorders. In a first study including 63 patients with therapy resistant affective and schizophrenic spectrum disorders we applied conventional, validated neurological CSF investigation such as analysis of albumin, IgG, IgA, IgM, oligoclonal IgG and specific antibodies, cell count and interpreted the data by Reibergrams. In a second study, we applied the highly sensitive and specific multicolour flowcytometry of paired samples of CSF and peripheral blood cells to characterize the immunostatus of psychiatric and neurological patients. We demonstrate that flowcytometry technology constitutes an appropriate method to investigate subsets of lymphocytes even with low CSF cell numbers, and therefore as a promising diagnostic tool for routine purposes in the differential diagnosis of psychiatric diseases. Furthermore, knowledge of the frequencies of T cell subsets such as the T regulatory cell type might open new avenues to models of psychiatric and neurological diseases as well as diagnostic and monitoring implications.

Inflammation and its discontents: the role of cytokines in the pathophysiology of major depression

Recognition that inflammation may represent a common mechanism of disease has been extended to include neuropsychiatric disorders including major depression. Patients with major depression have been found to exhibit increased peripheral blood inflammatory biomarkers, including inflammatory cytokines, which have been shown to access the brain and interact with virtually every pathophysiologic domain known to be involved in depression, including neurotransmitter metabolism, neuroendocrine function, and neural plasticity. Indeed, activation of inflammatory pathways within the brain is believed to contribute to a confluence of decreased neurotrophic support and altered glutamate release/reuptake, as well as oxidative stress, leading to excitotoxicity and loss of glial elements, consistent with neuropathologic findings that characterize depressive disorders. Further instantiating the link between inflammation and depression are data demonstrating that psychosocial stress, a well-known precipitant of mood disorders, is capable of stimulating inflammatory signaling molecules, including nuclear factor kappa B, in part, through activation of sympathetic nervous system outflow pathways. Interestingly, depressed patients with increased inflammatory biomarkers have been found to be more likely to exhibit treatment resistance, and in several studies, antidepressant therapy has been associated with decreased inflammatory responses. Finally, preliminary data from patients with inflammatory disorders, as well as medically healthy depressed patients, suggest that inhibiting proinflammatory cytokines or their signaling pathways may improve depressed mood and increase treatment response to conventional antidepressant medication. Translational implications of these findings include the unique opportunity to identify relevant patient populations, apply immune-targeted therapies, and monitor therapeutic efficacy at the level of the immune system in addition to behavior.

The antidepressant venlafaxine ameliorates murine experimental autoimmune encephalomyelitis by suppression of pro-inflammatory cytokines

Antidepressants are known to impact on the immune system. In this study, we examined the immunomodulatory properties of venlafaxine, a selective serotonin/norepinephrine reuptake inhibitor (SNRI), in murine experimental autoimmune encephalomyelitis (EAE), a T-cell-mediated CNS demyelinating disease model of multiple sclerosis. EAE was induced in SJL/J mice by adoptive transfer of myelin-specific T cells. Mice received different doses of venlafaxine before induction and after onset of disease. Sustained daily oral treatment with 6, 20 and 60 mg/kg significantly ameliorated the clinical symptoms of the disease compared to vehicle during both preventive and therapeutic intervention. Venlafaxine suppressed the generation of pro-inflammatory cytokines IL-12 p40, TNF-alpha and IFN-gamma in encephalitogenic T-cell clones, splenocytes and peritoneal macrophages in vitro. It also diminished mRNA expression of a number of inflammatory genes in the inflamed CNS tissue, among them CD3, CD8, Granzyme B, IL-12 p40, IFN-gamma, TNF-alpha and the chemokines Ccl2 and RANTES, whereas the expression of brain-derived neurotrophic factor was increased. These findings demonstrate the strong immunomodulatory property of the selective SNRI venlafaxine. Further studies are warranted to clarify whether venlafaxine may exert similar effects in humans.

A potential role for pro-inflammatory cytokines in regulating synaptic plasticity in major depressive disorder

A growing body of data suggests that hyperactivation of the immune system has been implicated in the pathophysiology of major depressive disorder (MDD). Several pro-inflammatory cytokines, such as tumour necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) have been found to be significantly increased in patients with MDD. This review focuses on these two cytokines based on multiple lines of evidence from genetic, animal behaviour, and clinical studies showing that altered levels of serum TNF-alpha and IL-1 are associated with increased risk of depression, cognitive impairments, and reduced responsiveness to treatment. In addition, recent findings have shown that centrally expressed TNF-alpha and IL-1 play a dual role in the regulation of synaptic plasticity. In this paper, we review and critically appraise the mechanisms by which cytokines regulate synaptic and neural plasticity, and their implications for the pathophysiology and treatment of MDD. Finally, we discuss the therapeutic potential of anti-inflammatory-based approaches for treating patients with severe mood disorders. This is a promising field for increasing our understanding of the mechanistic interaction between the immune system, synaptic plasticity, and antidepressants, and for the ultimate development of novel and improved therapeutics for severe mood disorders.

Increased phospholipase A2 activity and inflammatory response but decreased nerve growth factor expression in the olfactory bulbectomized rat model of depression: effects of chronic ethyl-eicosapentaenoate treatment

An increased inflammatory response and deficient synthesis of neurotrophic factors (NTFs) may contribute to the etiology of depression. However, the interrelationship between inflammation and NTFs is unknown. Recently, ethyl-eicosapentaenoate (EPA) has been used to treat depression. The mechanism by which EPA benefits depression is also unclear. Using the olfactory bulbectomized (OB) rat model of depression, this study evaluated two pathways from bulbectomy to the induction of depression-like changes (the inflammation-hypothalamic-pituitary-adrenal axis-stress response pathway and inflammation-nerve growth factor-memory pathway) and the effect of EPA on these pathways. When compared with sham-operated rats fed a control diet, significantly increased locomotor and rearing activities in an "open field," impaired memory in the Morris water maze, increased expression of corticotrophin-releasing factor (CRF), and increased secretion of corticosterone were found in OB rats. mRNA expression of nerve growth factor (NGF) was significantly lower in the hippocampus, and phospholipase A2 (PLA2) was higher in the hypothalamus; this change was associated with increased interleukin-1beta (IL-1beta) and prostaglandin E2 (PGE2) in the serum and brain. EPA treatments normalized these behavioral impairments and reduced CRF expression and corticosterone secretion. EPA also reduced serum concentrations of IL-1beta and PGE2, but reversed NGF reduction. Similar to the effects of EPA, the anti-inflammatory drug celecoxib significantly reduced blood PGE2, IL-1beta, and corticosterone concentrations and increased NGF expression in OB rats. Furthermore, anti-NGF treatment blocked EPA effects on behavior. These results suggest that an interaction exists between inflammation and NGF in the depression model. EPA may improve depression via its anti-inflammation properties and the upregulation of NGF.

Chronic treatment with celecoxib reverses chronic unpredictable stress-induced depressive-like behavior via reducing cyclooxygenase-2 expression in rat brain

Recent clinical trails reported that adjunctive cyclooxygenase (COX)-2 inhibition with celecoxib is beneficial in treating depression. However, another clinical study showed celecoxib did not have inhibitory effect of COX-2 in human brain when given at a therapeutic dose. Therefore, whether celecoxib is exerting its influence through COX inhibition or by some other mechanism remains unclear. The present study further investigated the effect of celecoxib on COX-2 expression, prostaglandin E(2) (PGE2, a major COX-2-mediated inflammatory mediator) concentration and the depressive-like behaviors in rats. Celecoxib was administrated by oral gavage to naive rats (16 mg/kg) or stressed rats (2, 8, 16 mg/kg, respectively) for 21 days, or to stressed rats for a single dose (16 mg/kg). The results showed that 21 days chronic unpredictable stress induced depressive-like behaviors and increased the COX-2 expression and PGE2 concentration in rat brain. Chronic treatments with celecoxib alleviated the depressive-like behavior and reversed the levels of COX-2 expression and PGE2 concentration in stressed rat in a dose-dependent manner. Celecoxib also improved the emotional state and decreased COX-2 expression and PGE2 concentration in naive rats. In addition, a single dose of celecoxib treatment reversed COX-2 expression and PGE2 concentration, but didn't alter the depressive-like behavior in stressed rat. These results suggest that COX-2 enzyme might play a key role in pathophysiology of depression. Furthermore, these data indicate that chronic celecoxib treatment reverse chronic unpredictable stress-induced depressive-like behavior might via reducing COX-2 enzyme in brain, and the selective COX-2 inhibitors could be developed as potential remedies for the management of depression.

Increased soluble tumor necrosis factor-alpha receptors in patients with major depressive disorder

AIM

Several lines of evidence suggest that major depressive disorder is associated with an inflammatory status. Tumor necrosis factor-alpha has been investigated as a potential molecular target in mood disorders. Tumor necrosis factor-alpha exerts its activity through binding to specific cell membrane receptors named as TNFR1 and TNFR2. The aim of the present study was to investigate soluble plasma TNFR1 (sTNFR1) and TNFR2 levels (sTNFR2) in major depressive disorder patients.

METHODS

Female outpatients with major depressive disorder (n = 30) were compared with a healthy control group (n = 19). Severity of depressive symptoms was evaluated on Beck Depression Inventory; post-traumatic stress disorder (PTSD) symptoms were evaluated on PTSD Checklist-Civilian Version; and childhood abuse and neglect on the Childhood Trauma Questionnaire. Plasma tumor necrosis factor-alpha and its soluble receptors were measured by ELISA.

RESULTS

Patients had no changes in tumor necrosis factor-alpha concentrations but did have increased sTNFR1 (P < 0.001) and sTNFR2 (P < 0.001) levels compared to controls. Plasma level of sTNFR1 was positively predicted by age (B = 0.25, P = 0.05) and PTSD-like symptoms (B = 0.41, P = 0.002) and plasma levels of sTNFR2 by depression severity (B = 0.67, P < 0.001).

CONCLUSIONS

Soluble tumor necrosis factor-alpha receptors could be reliable markers of inflammatory activity in major depression.

A randomized, double-blind, placebo-controlled study of preemptively administered intravenous parecoxib: effect on anxiety levels and procedural pain during epidural catheter placement for surgical operations or for chronic pain therapy

BACKGROUND

The effect of parecoxib, when used perioperatively or during interventional techniques, is well demonstrated in the literature. Little is known about its effects on anxiety levels before the analgesic technique application. The aim of this prospective, randomized, double-blind, placebo-controlled, clinical study is to investigate whether parecoxib, preemptively administrated, has an effect on anxiety levels reported prior to an epidural puncture, and if it influences the reported pain of the interventional technique itself.

MATERIAL AND METHODS

The study protocol involved 110 patients, scheduled for epidural catheter placement for chronic pain therapy--Group I, as well as 112 patients scheduled for orthopedic operations under epidural anesthesia--Group II. Patients in each group were randomly allocated into two subgroups in relation to parecoxib/placebo administration before epidural catheter placement: Group Ia, parecoxib 40 mg i.v. (n = 54), Group Ib, placebo (n = 56), Group IIa, parecoxib 40 mg i.v. (n = 57), Group IIb, placebo (n = 55). Patients were given a self-administered inventory to measure the anxiety level of the presurgical/preprocedural state (State-Trait Spielberger Anxiety Inventory) and anxiety levels were recorded 1 hour before epidural puncture, 20 minutes postdosing, and 1 hour after epidural catheter placement. Anxiety levels were also measured and recorded using visual analog scale (VAS). One hour after epidural puncture, reported procedural pain was recorded (VAS). One hour and 6 hours postepidural, patients' satisfaction was also recorded, on a 4-point scale.

RESULTS

All four subgroups were similar regarding demographic, operative/procedural data, and coexisting diseases. Preprocedural anxiety levels were significantly decreased with parecoxib administration in comparison with placebo in both groups (P < 0.05). Reported VAS regarding pain from epidural puncture was lower in Groups IA and Ib. Patients' satisfaction was greater with parecoxib in comparison with placebo.

CONCLUSION

The levels of anxiety have been investigated in several medical procedures and early, in the study of pain. The higher the expectation of pain and the anxiety are, the higher the intensity of the pain. Parecoxib seems to exert positive influence on pain and anxiety levels of interventional procedure. Further studies are needed to elucidate the actual mechanisms that are involved.

Future drugs for the treatment of depression: the need to look beyond monoamine systems

Review of extant biological data would suggest that major depressive disorder (MDD) is a term used to subsume a syndrome that may involve a variety of different pathophysiological processes. Current research has implicated a myriad of different factors in the pathogenesis of depressive disorders including: genetic predisposition, “hormonal” abnormalities, disturbances in neurostransmitters, disturbances in neurocircuitry, and immune dysfunction. Our most recent consensus suggests that the depressive disorders reflect the interplay between these biological systems and psychosocial experiences, such as early-life trauma and current life stressors. Thus, MDD truly represents a complex heterogeneous syndrome. This conceptualization suggests that a variety of different types of treatment approaches will be necessary to adequately ameliorate the symptoms of patients suffering from this syndrome. Although this is a daunting task, we are beginning to develop approaches that will enable us to add to our armamentation of biological treatments.