Plasma cytokine profiles in depressed patients who fail to respond to selective serotonin reuptake inhibitor therapy

Melancholic and atypical major depression--connection between cytokines, psychopathology and treatment

BACKGROUND AND PURPOSE

Growing scientific evidence indicates that there is a correlation between depression and alternations in the immune system. The main aim of the study was to investigate serum levels of Interleukin-6 (IL-6) and Tumour Necrosis Factor-alpha (TNF-α) in melancholic and atypical depressive patients during acute exacerbations of illness, compared to healthy subjects. The secondary aim was to explore a possible association between cytokine levels and clinical characteristics, as well as total duration of prior antidepressant treatment.

METHOD

We measured serum levels of IL-6 and TNF-α in 47 patients suffering from major depressive disorder (MDD) (29 melancholic and 18 atypical) in exacerbation of illness, compared to 39 healthy controls, matched by sex, body mass index (BMI) and smoking habits. Serum levels of IL-6 and TNF-α were measured by enzyme-linked immunosorbent assay (ELISA). The severity of psychopathology was assessed using the Hamilton Depression Rating Scale (HDRS).

RESULTS

IL-6 was significantly elevated in melancholic depressive patients (MDD-M) compared to healthy controls, while no difference was found between the patients with atypical depression (MDD-A) and the healthy group. Lower TNF-α serum level was found both in melancholic and in patients with atypical depression, compared with healthy subjects. We detected a positive correlation between cytokine levels in atypical, but not in melancholic subjects. Sex, age, smoking habits and BMI were not associated to cytokine levels in neither group. Clinical parameters (duration of illness, current episode, age of onset) were related to cytokine levels in atypical depression, while the duration of lifetime exposure to antidepressant treatment correlated to IL-6 serum levels in both melancholic and atypical depression.

CONCLUSION

Our results suggest that the difference in pro-inflammatory cytokine levels could reflect a biological difference between melancholic and atypical depression. A positive correlation between the cytokines (TNF-α and IL-6) observed in depressive patients with atypical features, might be influenced by chronic course of illness, while IL-6 elevation could represent a state indicator for acute exacerbation, especially in melancholic patients. Total duration of antidepressant treatment could be a relevant factor influencing the immune status of patients who suffer either from melancholic or atypical depression.

Lack of clinical therapeutic benefit of antidepressants is associated overall activation of the inflammatory system

Despite the evidence of an association between depression and increased inflammatory markers, still little is known in relation to the most severe cases of the disorder i.e., those who fail to respond to antidepressants. We have assessed the cytokine profile and cortisol levels in 21 healthy controls (HC) and 19 medicated patients with depression with treatment-resistance (TRD) moderately ill. As an initial exploratory analysis, we have also related cytokine profile to the patient's clinical treatment outcome after an inpatient admission. Cytokine profile was measured in the serum by the Cytokine Array I kit (Randox). Plasma cortisol was carried out using a commercially available for the IMMULITE system. When compared to healthy controls, depressed patients had higher levels of cortisol, IL-6, IL-10, but lower levels of IL-4 and VEGF. Our exploratory analysis showed subjects who did not go on to respond to the inpatient admission treatment package had lower levels of MCP-1, and a trend toward lower levels of VEGF. Taking together, these data suggest that lack of clinical therapeutic benefit of antidepressants is associated with overall activation of the inflammatory system.

Interplay between pro-inflammatory cytokines and growth factors in depressive illnesses

The development of depressive disorders had long been attributed to monoamine variations, and pharmacological treatment strategies likewise focused on methods of altering monoamine availability. However, the limited success achieved by treatments that altered these processes spurred the search for alternative mechanisms and treatments. Here we provide a brief overview concerning a possible role for pro-inflammatory cytokines and growth factors in major depression, as well as the possibility of targeting these factors in treating this disorder. The data suggest that focusing on one or another cytokine or growth factor might be counterproductive, especially as these factors may act sequentially or in parallel in affecting depressive disorders. It is also suggested that cytokines and growth factors might be useful biomarkers for individualized treatments of depressive illnesses.

Prolonged restraint stress increases IL-6, reduces IL-10, and causes persistent depressive-like behavior that is reversed by recombinant IL-10

Altered inflammatory cytokine profiles are often observed in individuals suffering from major depression. Recent clinical work reports on elevated IL-6 and decreased IL-10 in depression. Elevated IL-6 has served as a consistent biomarker of depression and IL-10 is proposed to influence depressive behavior through its ability to counterbalance pro-inflammatory cytokine expression. Clinical and animal studies suggest a role for IL-10 in modifying depressive behavior. Murine restraint stress (RST) is regularly employed in the study of behavioral and biological symptoms associated with depressive disorders. While responses to acute RST exposure have been widely characterized, few studies have examined the ongoing and longitudinal effects of extended RST and fewer still have examined the lasting impact during the post-stress period. Consistent with clinical data, we report that a protocol of prolonged murine RST produced altered cytokine profiles similar to those observed in major depressive disorder. Parallel to these changes in circulating cytokines, IL-10 mRNA expression was diminished in the cortex and hippocampus throughout the stress period and following cessation of RST. Moreover, chronic RST promoted depressive-like behavior throughout the 28-day stress period and these depressive-like complications were maintained weeks after cessation of RST. Because of the correlation between IL-10 suppression and depressive behavior and because many successful antidepressant therapies yield increases in IL-10, we examined the effects of IL-10 treatment on RST-induced behavioral changes. Behavioral deficits induced by RST were reversed by exogenous administration of recombinant IL-10. This work provides one of the first reports describing the biological and behavioral impact following prolonged RST and, taken together, this study provides details on the correlation between responses to chronic RST and those seen in depressive disorders.

Antidepressant-like effect of flaxseed secoisolariciresinol diglycoside in ovariectomized mice subjected to unpredictable chronic stress

Secoisolariciresinol diglycoside (SDG), a predominant lignan in flaxseed, has antioxidant activity as a dietary supplement. The purpose of the present study was to investigate the antidepressant-like effect and the possible mechanism of flaxseed SDG when the ovariectomized mice were exposed to the unpredictable chronic mild stress procedure. Chronic stress induced the increases in immobility time in mouse model of despair tests, but administration with SDG (80 and 160 mg/kg, p.o.) for 21 days inhibited these behavioral changes caused by stress in both forced swimming and tail suspension tests. These doses that affected the immobile response did not affect locomotor activity. Moreover, the changes in the serum corticosterone and adrenocorticotropic hormone (ACTH) levels were also measured to explore the SDG-associated regulation of hypothalamus-pituitary-adrenals (HPA) axis. The results indicated that the chronic stress-induced increases in the serum corticosterone and ACTH were reversed by treatment with high doses of SDG. Chronic treatment with SDG also affected the body weight of mice and IL-6, IL1β levels in the frontal cortex. In addition, chronic stress procedure induced a decrease in brain-derived neurotrophic factor (BDNF) expression in the frontal cortex of mice; while treatment with SDG reversed this reduction of BDNF. All these results provide compelling evidence that the behavioral effects of flaxseed SDG in the ovariectomized mice might be related to their modulating effects on the neuroendocrine-immune network and neurotrophin factor expression.

A dialogue between the immune system and brain, spoken in the language of serotonin

Neuropsychiatric disorders have long been linked to both immune system activation and alterations in serotonin (5-HT) signaling. In the CNS, the contributions of 5-HT modulate a broad range of targets, most notably, hypothalamic, limbic and cortical circuits linked to the control of mood and mood disorders. In the periphery, many are aware of the production and actions of 5-HT in the gut but are unaware that the molecule and its receptors are also present in the immune system where evidence suggests they contribute to the both innate and adaptive responses. In addition, there is clear evidence that the immune system communicates to the brain via both humoral and neuronal mechanisms, and that CNS 5-HT neurons are a direct or indirect target for these actions. Following a brief primer on the immune system, we describe our current understanding of the synthesis, release, and actions of 5-HT in modulating immune function, including the expression of 5-HT biosynthetic enzymes, receptors, and transporters that are typically studied with respect to the roles in the CNS. We then orient our presentation to recent findings that pro-inflammatory cytokines can modulate CNS 5-HT signaling, leading to a conceptualization that among the many roles of 5-HT in the body is an integrated physiological and behavioral response to inflammatory events and pathogens. From this perspective, altered 5-HT/immune conversations are likely to contribute to risk for neurobehavioral disorders historically linked to compromised 5-HT function or ameliorated by 5-HT targeted medications, including depression and anxiety disorders, obsessive-compulsive disorder (OCD), and autism. Our review raises the question as to whether genetic variation impacting 5-HT signaling genes may contribute to maladaptive behavior as much through perturbed immune system modulation as through altered brain mechanisms. Conversely, targeting the immune system for therapeutic development may provide an important opportunity to treat mental illness.

Quest for biomarkers of treatment-resistant depression: shifting the paradigm toward risk

The search for potential biomarkers of psychiatric disorders is a central topic in biological psychiatry. This review concerns published studies on potential biomarkers of treatment-resistant depression (TRD). The search for biomarkers of TRD in the bloodstream has focused on cytokines and steroids as well as brain-derived neurotropic factor. Additional approaches to identifying biomarkers of TRD have dealt with cerebrospinal fluid analysis, magnetic resonance imaging, and positron emission tomography. Some studies have also investigated potential genetic and epigenetic factors in TRD. Most studies have, however, used a post hoc experimental design that failed to determine the association between biomarkers and the initial risk of TRD. Particular attention in future studies should be on shifting the experimental paradigm toward procedures that can determine the risk for developing treatment resistance in untreated depressed individuals.

Evidence for sustained elevation of IL-6 in the CNS as a key contributor of depressive-like phenotypes

There is compelling clinical literature implicating a role for cytokines in the pathophysiology of major depressive disorder (MDD). Interleukin-6 (IL-6) and interleukin-1β (IL-1β) are pleiotropic inflammatory cytokines that have been reported to be elevated in patients with MDD. The present studies were undertaken to investigate the relationship between IL-6 and IL-1β in animal models of depressive-like behavior. Analysis of brain tissue homogenates in the cortex of rats subjected to chronic stress paradigms revealed elevated levels of IL-6 protein in the absence of elevations in IL-1β. Central administration of recombinant mouse IL-6 produced depressive-like phenotypes in mice, which were not accompanied by IL-1β-induced increases in the brain tissue or IL-1β-related sickness behavior typical of a general central nervous system inflammatory response. Systemic administration of fluoxetine in the presence of centrally administered IL-6 failed to produce the expected antidepressant-like response in mice relative to sham-infused controls. Further, administration of fluoxetine to mice with endogenous overexpression of brain IL-6 (MRL/MpJ-Fas(LPR/LPR) (LPR mice)) failed to produce the expected antidepressant-like effect relative to fluoxetine-treated control mice (MRL/MpJ(+/+)). Interestingly, blockade of IL-6 trans-signaling by coadministration of a gp130/Fc monomer or an anti-mouse IL-6 antibody with IL-6 prevented the IL-6-induced increases in immobility time as well as attenuated IL-6-induced increases of protein in the cortex. Taken together, these data indicate that elevations in IL-6 may have a pathophysiological role underlying depression and more specifically resistance to current classes of antidepressant medications and suggest that modulation of the IL-6 signaling pathway may have therapeutic potential for treatment-resistant depression.

Effects of a putative antidepressant with a rapid onset of action in defeated mice with different coping strategies

There is evidence suggesting that stressful social events may result in depressive-like disorders, but the development of these disorders depend on the way in which people cope with stress. Although antidepressants are useful their drawback is a delay in the therapeutic effects, moreover not all the patients show an adequate response to this treatment. The aim of this study was to analyse the effect of RS 67333, which is a 5-HT(4) receptor partial agonist and a putative antidepressant which exhibits a rapid onset of action and to determine whether this drug reverses the behavioural and physiological effects that are generated by chronic defeat in subjects who manifest a more vulnerable profile in their response to stress. Male mice were exposed to defeat for 21 consecutive days using a sensorial contact model. After 18 days of defeat, 2 groups of subjects were established, active and passive, in accordance with the behaviour that was manifested during social confrontation, and drug treatment was initiated for 5 days. Finally, the animals were subjected to a forced swimming test (FST). The results revealed higher corticosterone levels in passive mice after the last defeat. Additionally, 3 days after the last defeat, they showed lower corticosterone levels and higher splenic IL-6 and TNF-α levels and hypothalamic GR mRNA levels when compared to their active and manipulated control counterparts. Passive mice had higher 5-HT(1A) receptor mRNA levels than the manipulated controls and a lower MR/GR ratio than active mice. Similar to stress, the drug increased hypothalamic GR mRNA levels, but it did not affect other measured physiological variables or social behaviour, which suggested that the mechanism of this drug is not the most adequate for reversing stress-induced effects in this model. Nevertheless, the treatment increased swimming and decreased immobility in the FST, suggesting an antidepressant potential for this drug.

Interleukin (IL)-6, tumour necrosis factor alpha (TNF-α) and soluble interleukin-2 receptors (sIL-2R) are elevated in patients with major depressive disorder: a meta-analysis and meta-regression

BACKGROUND

Many studies have explored the association between soluble interleukin-2 receptor (sIL-2R), cytokines and major depressive disorder (MDD). However, the results of these studies were not consistent. The aim of our study is to compare the levels of sIL-2R and cytokines in the blood between MDD patients and controls by a meta-analysis and to identify moderators accounting for potential heterogeneity in the levels of sIL-2R and cytokines in MDD patients versus controls by meta-regression analyses.

METHODS

A comprehensive literature search was performed to identify studies comparing the levels of sIL-2R and cytokines between MDD patients and controls. We pooled the effect sizes for standardized mean differences (SMD) of the levels of sIL-2R and cytokines. We also performed meta-regression and sensitivity analyses to investigate the roles of age, gender, sample type, ethnic origin and selected studies' quality in explaining potential heterogeneity and differences in results respectively.

RESULTS

Twenty-nine studies were selected for this analysis. The levels of sIL-2R, TNF-α and IL-6 in MDD patients were significantly higher than those of healthy controls (SMD=0.555, p<0.001, SMD=0.567, p=0.010; SMD=0.680, p<0.001). Mean age of all subjects was a significant moderator to explain the high heterogeneity of IL-6. Sensitivity analysis found that European but not non-European subjects have higher levels difference of sIL-2R, TNF-α and IL-1β between MDD patients and controls.

LIMITATION

The severity of MDD was not considered.

CONCLUSION

The blood levels of sIL-2R, TNF-α and IL-6 were significantly higher in MDD patients than controls. Age, samples source and ethnic origins may play a potential role in heterogeneity.

Crosstalk between metabolic and neuropsychiatric disorders

Evidence supporting the concurrence of metabolic disturbances (e.g. insulin resistance, diabetes and obesity) and neuropsychiatric disorders has been demonstrated in both human and animal studies, suggesting the possibility that they have shared pathophysiological mechanisms. During the past decade, our understanding for the role of insulin in both normal and abnormal central nervous system (CNS) processes has become increasingly refined. Evidence indicates that insulin is a pleiotropic peptide, critical to neurotrophism, neuroplasticity, and neuromodulation. Moreover, the role of insulin underscores its importance in the development of several neuropsychiatric disorders, including, but not limited to, mechanisms involved in the pathogenesis and progression towards diabetes, obesity, and neurodegenerative disorders, such as Alzheimer's disease. This review focuses on the insulin-mediated effects on normal and abnormal brain function and discusses why targeting insulin-related pathways in the brain may emerge as a new approach for refining treatment of neurological and psychiatric disorders.

Depression and sickness behavior are Janus-faced responses to shared inflammatory pathways

It is of considerable translational importance whether depression is a form or a consequence of sickness behavior. Sickness behavior is a behavioral complex induced by infections and immune trauma and mediated by pro-inflammatory cytokines. It is an adaptive response that enhances recovery by conserving energy to combat acute inflammation. There are considerable phenomenological similarities between sickness behavior and depression, for example, behavioral inhibition, anorexia and weight loss, and melancholic (anhedonia), physio-somatic (fatigue, hyperalgesia, malaise), anxiety and neurocognitive symptoms. In clinical depression, however, a transition occurs to sensitization of immuno-inflammatory pathways, progressive damage by oxidative and nitrosative stress to lipids, proteins, and DNA, and autoimmune responses directed against self-epitopes. The latter mechanisms are the substrate of a neuroprogressive process, whereby multiple depressive episodes cause neural tissue damage and consequent functional and cognitive sequelae. Thus, shared immuno-inflammatory pathways underpin the physiology of sickness behavior and the pathophysiology of clinical depression explaining their partially overlapping phenomenology. Inflammation may provoke a Janus-faced response with a good, acute side, generating protective inflammation through sickness behavior and a bad, chronic side, for example, clinical depression, a lifelong disorder with positive feedback loops between (neuro)inflammation and (neuro)degenerative processes following less well defined triggers.

Microvascular pathology in late-life depression

Since the era of Gaupp who introduced the concept of atheroscletic depressive disorder, the concept of late-life depression has been correlated with cerebrovascular comorbidities, microvascular lesions, frontal cortical and subcortical gray and white matter hyperintensities. The predominant neuropsychological deficits concern the domains of planning, organization and abstraction, with executive dysfunction being the predominant finding. MRI studies reveal a higher prevalence of white matter lesions in elderly patients with depression. Molecular mechanisms underlying the disease still remain unclear. Hyperhomocysteinemia has been associated with depression through its toxicity to neurons and blood vessels. Endothelial dysfunction is another possible mechanism referring to the loss of vasodilatation capacity. Inflammatory phenomena, such as increased peripheral leucocytes, elevated CRP and cytokine levels, could play a role in endothelial dysfunction. In this review we will briefly combine findings from neurobiological, epidemiological, structural and post-mortem data. A more complex model in late-life depression combining different modalities could be an elucidating approach to the disease's etiopathogeny in the future.

The role of cytokines and hot flashes in perimenopausal depression

BACKGROUND

An imbalance in the production of proinflammatory and anti-inflammatory cytokines may play a role in the pathophysiology of perimenopausal depression. The aim of this study was to examine serum levels of the proinflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor α (TNFα), and the anti-inflammatory cytokine IL-10, in perimenopausal women suffering from depression. Furthermore, to assess whether serum cytokine levels are associated with the presence of hot flashes or the use of selective serotonin reuptake inhibitors (SSRIs). We also evaluated the possible association of hot flashes and perimenopausal depression.

METHODS

Serum samples from 65 perimenopausal women, 41 with depression and 24 without depression, were assessed for serum IL-6, TNFα and IL-10 by conventional enzyme-linked immunosorbent assays. Depression was evaluated by the 17-item Hamilton Depression Rating Scale (HAM-D 17) and a psychiatric interview. The presence and severity of hot flashes were examined using the Menopause Rating Scale (MRS).

RESULTS

Serum levels cytokines did not differ between depressed women and normal controls. Serum levels of cytokines did not change significantly in depressed women with hot flashes or in depressed women treated with SSRIs. Hot flashes were strongly associated (P < 0.0001) with perimenopausal depression.

CONCLUSION

The study supports the hypothesis that perimenopausal depression is not characterized by increased proinflammatory cytokines and decreased anti-inflammatory cytokines. Women with perimenopausal depression suffer from more severe and more frequent hot flashes than women without perimenopausal depression.

New drug targets in depression: inflammatory, cell-mediated immune, oxidative and nitrosative stress, mitochondrial, antioxidant, and neuroprogressive pathways. And new drug candidates--Nrf2 activators and GSK-3 inhibitors

This paper reviews new drug targets in the treatment of depression and new drug candidates to treat depression. Depression is characterized by aberrations in six intertwined pathways: (1) inflammatory pathways as indicated by increased levels of proinflammatory cytokines, e.g. interleukin-1 (IL-1), IL-6, and tumour necrosis factor α. (2) Activation of cell-mediated immune pathways as indicated by an increased production of interferon γ and neopterin. (3) Increased reactive oxygen and nitrogen species and damage by oxidative and nitrosative stress (O&NS), including lipid peroxidation, damage to DNA, proteins and mitochondria. (4) Lowered levels of key antioxidants, such as coenzyme Q10, zinc, vitamin E, glutathione, and glutathione peroxidase. (5) Damage to mitochondria and mitochondrial DNA and reduced activity of respiratory chain enzymes and adenosine triphosphate production. (6) Neuroprogression, which is the progressive process of neurodegeneration, apoptosis, and reduced neurogenesis and neuronal plasticity, phenomena that are probably caused by inflammation and O&NS. Antidepressants tend to normalize the above six pathways. Targeting these pathways has the potential to yield antidepressant effects, e.g. using cytokine antagonists, minocycline, Cox-2 inhibitors, statins, acetylsalicylic acid, ketamine, ω3 poly-unsaturated fatty acids, antioxidants, and neurotrophic factors. These six pathways offer new, pathophysiologically guided drug targets suggesting that novel therapies could be developed that target these six pathways simultaneously. Both nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activators and glycogen synthase kinase-3 (GSK-3) inhibitors target the six above-mentioned pathways. GSK-3 inhibitors have antidepressant effects in animal models of depression. Nrf2 activators and GSK-3 inhibitors have the potential to be advanced to phase-2 clinical trials to examine whether they augment the efficacy of antidepressants or are useful as monotherapy.

No evidence for an anti-inflammatory effect of escitalopram intervention in healthy individuals with a family history of depression

Inflammation may contribute to the pathogenesis of depression and antidepressants are hypothesised to have an anti-inflammatory effect. In this randomised double-blinded trial we investigated the cytokine levels in supernatants of stimulated whole blood samples from first degree relatives to patients with depression randomised to a single daily dose of either 10mg escitalopram or placebo for four weeks. No significant differences were found in any of the cytokine levels between the participants treated with escitalopram (n=21) or placebo (n=23). Our data does thus not support the hypothesis of a global anti-inflammatory effect of escitalopram on cytokines in healthy subjects.

A possible role to nitric oxide in the anti-inflammatory effects of amitriptyline

Antidepressants are reported to display anti-inflammatory effects. Nitric oxide (NO), in turn, has a key role in inflammation. The objective of the present study was to evaluate the effect of amitriptyline co-administered with L-NAME (a NO synthase inhibitor) on certain parameters of acute inflammatory response in rats, as a form to investigate a possible participation of NO in the anti-inflammatory effects of amitriptyline. For this, two animal models were used: carrageenan-induced paw edema and acute peritonitis. In the last one, peritoneal exudate, adhesion molecules expression by peripheral blood leukocytes and serum cytokines levels were evaluated. In a noninflammatory condition, serum levels of nitrates were determined. L-NAME induced a potentiation of the anti-inflammatory effects of amitriptyline (p < 0.05) in the paw edema model; however, these effects were not abrogated when L-NAME was substituted by L-arginine administration. A decrease in both leukocyte concentration and total number of cells in the peritoneal exudate and a reduction in the total serum levels of nitrates were observed with co-administration of L-NAME and amitriptyline (p < 0.05). No significant differences among groups were found concerning the expression of adhesion molecules by peripheral blood leukocytes (p > 0.05). There was a significant decrease on IL-1β and TNF-α serum levels in the experimental groups when compared to the control animals. Together the present results and the literature suggest that the anti-inflammatory effects of amitriptyline may be due to a decrease in NO production. A decrease in IL-1β/TNF-α serum levels may also be implicated in the results observed.

Proinflammatory and "resiliency" proteins in the CSF of patients with major depression

BACKGROUND

A number of studies have shown that elevated levels of inflammatory cytokines may promote depression and suicidal ideation and that neuroprotective peptides may decrease the response to stress and depression. In this study, cerebrospinal fluid (CSF) levels of three inflammatory cytokines (IL-1, IL-6, and tumor necrosis factor α (TNFα)) and two putative "resiliency" neuropeptides (brain-derived neurotrophic factor (BDNF) and neuropeptide Y (NPY)) were compared between patients with depression and healthy controls.

METHODS

Eighteen patients with major depression and 25 healthy controls underwent a lumbar puncture; CSF samples were withdrawn and assayed for IL-1, IL-6, TNFα, BDNF, and NPY levels. Patients with depression were then entered into an 8-week treatment protocol and had repeated lumbar puncture procedures post-treatment.

RESULTS

Contrary to prediction, we found that at baseline depressed patients had higher CSF NPY concentration compared to the normal comparison group. Within the depressed patients, we found several statistically significant correlations between elevated CSF cytokine levels and clinical severity.

CONCLUSION

Despite the small sample size, given the challenges in obtaining CSF from patients with depression these data are of interest in confirming some aspects of the inflammatory hypothesis of depression.

Treatment response and cognitive impairment in major depression: association with C-reactive protein

Levels of inflammatory markers have been found to be significantly associated with major depressive disorder (MDD) and cognitive impairment. The aim of this study was to investigate whether the level of C-reactive protein (CRP) is correlated with depressive mood and cognitive impairment in MDD patients. In 149 subjects with MDD, the 21-item Hamilton Rating Scale for Depression (HAM-D), Continuous Performance Test (CPT), Finger-Tapping Test (FTT), and Wisconsin Card-Sorting Test (WCST) were administered before and after antidepressant treatment. Besides, the level of CRP was measured. After 6weeks of treatment, the total HAM-D scores decreased significantly. In addition, the subjects' performance in the masked CPT and the WCST with completed categories significantly improved (p<0.001 and p=0.027, respectively) after the reliable change indices were corrected for practice effects. The CRP levels had increased significantly after six weeks of treatment after adjustment for age and gender (p<0.001). In addition, the CRP levels remained significantly high after six weeks of treatment in patients with a higher baseline level (r=0.657, p<0.001). Although the association between baseline CRP level and HAM-D score was not significant, the baseline CRP level was significantly correlated with treatment response at week 2 (r=0.327, p=0.020). The baseline CRP level was also negatively correlated with performance in the FTT before treatment (r=-0.580, p=0.006). Moreover, the baseline CRP level was significantly correlated with performance in the FTT (r=-0.501, p=0.021) and WCST with completed categories (r=-0.521, p=0.015) at week 6. The cognitive function of patients with high baseline CRP levels might remain impaired even if their mood symptoms improve after antidepressant treatment. Whether adjunctive anti-inflammatory medication may help to preserve cognitive function merits further investigation.

Cytokines as potential biomarkers for Parkinson's disease: a multiplex approach

Cytokines, which are immunological messengers facilitating both intra- and inter-system communication, are considered central players in the neuroinflammatory cascades associated with the neurodegenerative process in Parkinson's disease (PD) and other neurological disorders. They have also been implicated in depression and other cognitive (e.g., memory impairment, dementia) and affective disturbances (e.g., anxiety) that show high co-morbidity with neurodegenerative diseases. As such, cytokines may hold great promise as serological biomarkers in PD, with potential applications ranging from early diagnosis and disease staging, to prognosis, drug discovery, and tracking the response to treatment. Subclassification or risk stratification in PD could be based (among other things) on reliably determined cytokine panel profiles or "signatures" of particular co-morbid disease states or at-risk groups (e.g., PD alone, PD with depression and/or dementia). Researchers and clinicians seeking to describe cytokine variations in health vs. disease will benefit greatly from technologies that allow a high degree of multiplexing and thus permit the simultaneous determination of a large roster of cytokines in single small-volume samples. The need for such highly paralleled assays is underscored by the fact that cytokines do not act in isolation but rather against a backdrop of complementary and antagonistic cytokine effects; ascribing valence to the actions of any one cytokine thus requires specific knowledge about the larger cytokine milieu. This chapter provides a technological overview of the major cytokine multiplex assay platforms before discussing the implications of such tools for biomarker discovery and related applications in PD and its depressive and cognitive co-morbidities.

A neuroimmunological perspective on anxiety disorders

OBJECTIVE

Research into psychoneuroimmunology has led to substantial advances in our understanding of the reciprocal interactions between the central nervous system and the immune system in neuropsychiatric disorders. To date, the presence of inflammatory responses and the crucial role of cytokines in major depression have been addressed in numerous studies. However, neuroinflammatory hypotheses in anxiety disorders have been studied less extensively than in major depression. There is a high research need for better understanding of both the heterogeneous role of specific cytokines in the control of anxious states and in different anxiety disorders and of the immunomodulating effects of antidepressants on anxiety.

METHODS

Relevant literature was identified through a search of MEDLINE via PubMed. We discuss recent research on neuroimmunology in anxiety and make methodological recommendations for future investigation of neuroinflammatory hypotheses in anxiety disorders.

RESULTS

Some accumulating evidence has indicated modulatory effects of cytokines on neuronal communication and anxiety; however, research has not revealed consistent reproducible findings.

CONCLUSIONS

The availability of inflammatory biomarkers may provide an opportunity to identify patients via specific pathophysiological processes and to monitor therapeutic responses within relevant pathways. Further understanding of the neuroimmunological mechanisms to untangle the reciprocal associations between inflammation and anxiety is warranted.

Serotonin reuptake inhibitor antidepressants (SSRIs) against atherosclerosis

Selective serotonin reuptake inhibitors (SSRIs) are a class of drug widely used for treatment of mood disorders, including depression and cardiovascular disease. A search for related articles in the PubMed database was attempted. It covered studies, reports, reviews and editorials of the last 5 years.

Pro-inflammatory cytokines, such as TNF-α, IL-1 and IL-6, stimulate central serotonin (5-HT) neurotransmission and are over-expressed in depression, which has been linked with hypothalamic-pituitary-adrenal axis (HPA) hyperactivity. They have also been implicated in the pathogenesis and progression of other stress-induced disorders, like myocardial infarction (MI) and coronary heart disease (CHD), as they seem to modulate cardiovascular function by a variety of mechanisms. Biological mechanisms like these may explain the link between depression and CHD. There are a variety of environmental factors as well as genetic factors that might influence the pharmacogenetics of antidepressant drugs. New generation selective serotonin reuptake inhibitor antidepressants (SSRIs) causing a reduced cardiovascular morbidity and mortality may be related to serotonin platelet abnormalities in depressed patients that are effectively treated by SSRIs. SSRIs such as fluoxetine, paroxetine, sertraline and citalopram are not only considered to be free from the cardiotoxicity of their predecessors but also to function as safe and efficacious agents against depression, platelet activation, atherosclerosis and development and prognosis of coronary heart disease. However, there is a need for more studies in order to establish the exact biochemical mechanisms that are responsible for these diseases and the immunoregulatory effects of chronic use of SSRI medications.

LPS inhibits the effects of fluoxetine on depression-like behavior and hippocampal neurogenesis in rats

Depressed patients with increased inflammatory cytokines in peripheral blood have been reported to be more likely to exhibit treatment resistance. However, it is unknown whether the inflammation influences the action of antidepressant drugs. Here, we investigated the influence of lipopolysaccharide (LPS) on the antidepressant action of fluoxetine in depressive rats induced by chronic unpredictable mild stress (CUMS). In this study, we first modified the CUMS paradigm by administration of LPS daily before the stressor, and then investigated the influence of inflammation on the antidepressant action of fluoxetine. The effects of stress exposure and antidepressant treatment were assessed by behavioral testing (sucrose preference test, forced swimming test, novelty suppressed feeding test) and hippocampal BrdU labeling. The CUMS-induced behavioral changes can be reversed by 4-week fluoxetine treatment. Fluoxetine also increased the hippocampal neurogenesis in the depressive rats. Pretreatment with LPS, to mimic inflammation, had no significant effect on depressive behavior but attenuated the antidepressant action of fluoxetine significantly. Thus, our results suggest that the inflammation might play a certain role in the pathophysiology of antidepressant treatment resistance.

The inflammation hypothesis in geriatric depression

BACKGROUND

A large body of research has focused on "mediating mechanisms" and predisposing brain abnormalities to geriatric depression, but little is known about its etiology. This paper examines whether age-related and comorbid disease-related immune deregulation is an etiologic contributor to geriatric depression.

METHODS

This article reviews findings on neuroinflammation during the aging process and depression as well as studies of anti-inflammatory actions of classical antidepressants and antidepressant actions of anti-inflammatory agents.

RESULTS

Aging results in increased peripheral immune responses, impaired peripheral-CNS immune communication, and a shift of the CNS into a pro-inflammatory state. These exaggerated and prolonged immune responses may lead to changes in the function of emotional and cognitive networks pertinent to geriatric depression and to behavioral changes reminiscent of the depressive and cognitive symptoms of geriatric depression. Some antidepressants may reduce the expression of inflammation markers. Limited data suggest that some anti-inflammatory agents may have antidepressant properties.

CONCLUSIONS

A synthesis of available findings suggests that aging-related and comorbid disease-related inflammatory processes may promote changes in the neural systems predisposing to geriatric depression or facilitating metabolic changes that mediate depressive syndromes. The "inflammation hypothesis" in geriatric depression cannot be tested in its entirety, but it can lead to testable hypotheses and data on mechanisms by which inflammatory processes promote geriatric depression. The significance of such an effort is that it may lead to a novel treatment development model bringing to bear recent advances of anti-inflammatory pharmacology to the treatment of depressed elderly patients.

Neurostimulation therapies for treatment resistant depression: a focus on vagus nerve stimulation and deep brain stimulation

Antidepressant treatments, including pharmacotherapy and psychotherapy, do not result in remission for the majority of patients with major depressive disorder. The high prevalence of treatment resistant depression (TRD) poses a significant issue for patients as well as both societal and economic costs. Due to the limited efficacy of existing therapies in this sub-population, alternative somatic treatments are being explored. Both vagus nerve stimulation (VNS) and deep brain stimulation (DBS) are neurostimulation treatments for TRD. While VNS has Food Drug Administration approval as an adjunctive therapy for MDD, DBS is still in the experimental stages. This article will review the evidence supporting the clinical utility of these therapies.

The keys to improving depression outcomes

The heterogeneity of symptoms within major depressive disorder poses significant challenges for treatment and it is likely that current pharmacotherapies do not target all symptoms equally, although they have similar efficacy rates. While there is still continuing interest in understanding monoamine interactions and consequent downstream effects, the limited efficacy and tolerability achieved with classical antidepressants provides a compelling argument to move beyond the monoamines. Several lines of biological research in depression exploring immune function, neurotrophins, amino acid and neuropeptide neurotransmitters, neuroanatomical function and circadian rhythms, may lead to novel therapeutic targets and enhance depression outcomes. This review will evaluate the evidence for emerging treatments as well as recommendations from current international guidelines regarding antidepressant management.

Regulation by glycogen synthase kinase-3 of inflammation and T cells in CNS diseases

Elevated markers of neuroinflammation have been found to be associated with many psychiatric and neurodegenerative diseases, such as mood disorders, Alzheimer's disease, and multiple sclerosis (MS). Since neuroinflammation is thought to contribute to the pathophysiology of these diseases and to impair responses to therapeutic interventions and recovery, it is important to identify mechanisms that regulate neuroinflammation and potential targets for controlling neuroinflammation. Recent findings have demonstrated that glycogen synthase kinase-3 (GSK3) is an important regulator of both the innate and adaptive immune systems' contributions to inflammation. Studies of the innate immune system have shown that inhibitors of GSK3 profoundly alter the repertoire of cytokines that are produced both by peripheral and central cells, reducing pro-inflammatory cytokines, and increasing anti-inflammatory cytokines. Furthermore, inhibitors of GSK3 promote tolerance to inflammatory stimuli, reducing inflammatory cytokine production upon repeated exposure. Studies of the adaptive immune system have shown that GSK3 regulates the production of cytokines by T cells and the differentiation of T cells to subtypes, particularly Th17 cells. Regulation of transcription factors by GSK3 appears to play a prominent role in its regulation of immune responses, including of NF-κB, cyclic AMP response element binding protein, and signal transducer and activator of transcription-3. Invivo studies have shown that GSK3 inhibitors ameliorate clinical symptoms of both peripheral and central inflammatory diseases, particularly experimental autoimmune encephalomyelitis, the animal model of MS. Therefore, the development and application of GSK3 inhibitors may provide a new therapeutic strategy to reduce neuroinflammation associated with many central nervous system diseases.

Peripheral anti-inflammatory effects explain the ginsenosides paradox between poor brain distribution and anti-depression efficacy

Background

The effectiveness of ginseng in preventing and treating various central nervous system (CNS) diseases has been widely confirmed. However, ginsenosides, the principal components of ginseng, are characterized by poor accessibility to the brain, and this pharmacokinetic-pharmacological paradox remains poorly explained. Anti-inflammatory approaches are becoming promising therapeutic strategies for depression and other CNS diseases; however, previous studies have focused largely on anti-inflammatory therapies directed at the central nervous system. It is thus of interest to determine whether ginsenosides, characterized by poor brain distribution, are also effective in treating lipopolysaccharide- (LPS) induced depression-like behavior and neuroinflammation.

Methods

In an LPS-induced depression-like behavior model, the antidepressant effects of ginseng total saponins (GTS) were assessed using a forced swimming test, a tail suspension test, and a sucrose preference test. The anti-inflammatory efficacies of GTS in brain, plasma, and LPS-challenged RAW264.7 cells were validated using ELISA and quantitative real-time PCR. Moreover, indoleamine 2,3-dioxygenase (IDO) activity in the periphery and brain were also determined by measuring levels of kynurenine/tryptophan.

Results

GTS significantly attenuated LPS-induced depression-like behavior. Moreover, LPS-induced increases in 5-HT and tryptophane turnover in the brain were significantly reduced by GTS. IDO activities in brain and periphery were also suppressed after pretreatment with GTS. Furthermore, GTS-associated recovery from LPS-induced depression-like behavior was paralleled with reduced mRNA levels for IL-1β, IL-6, TNF-α, and IDO in hippocampus. Poor brain distribution of ginsenosides was confirmed in LPS-challenged mice. GTS treatment significantly decreased production of various proinflammatory cytokines in both LPS-challenged mice and RAW264.7 cells.

Conclusion

This study suggests that the anti-depression efficacy of GTS may be largely attributable to its peripheral anti-inflammatory activity. Our study also strengthens an important notion that peripheral anti-inflammation strategies may be useful in the therapy of inflammation-related depression and possibly other CNS diseases.

Strategies to achieve clinical effectiveness: refining existing therapies and pursuing emerging targets

BACKGROUND

Clinical effectiveness reflects a balance between efficacy and tolerability as well as patient satisfaction and overall improvement in quality of life and function. This is of particular importance when considering the long term use of antidepressant therapies for relapse prevention.

METHODS

The purpose of this review is to explore methods to enhance the modest efficacy and effectiveness outcomes reported with current antidepressant strategies. Two strategies are addressed: a) Doing better with existing treatments and b) pursuing novel targets beyond the monoamine system for new antidepressant drug development.

RESULTS

In the first instance, it is important to consider the balance between antidepressant efficacy and tolerability for individual patients and also be aware of evidence supporting superiority of one agent over others. Both sequential and concurrent combination therapies with existing antidepressants are also reviewed. The second approach involves a review of emerging novel pharmacological treatments based on biomarker research. Unique targets where antidepressant treatments appear effective include the melatonergic, glutamatergic, neurotrophic, cytokine, and neuropeptide systems.

CONCLUSIONS

While agomelatine represents an example of a clinically available antidepressant that targets melatonin receptors, drugs that act on other candidate systems are still in the development phase.

Understanding the role of inflammatory-related pathways in the pathophysiology and treatment of psychiatric disorders: evidence from human peripheral studies and CNS studies

Many lines of evidence now support the hypothesis that inflammation-related pathways are involved in the pathophysiology of psychiatric disorders. Much of the data underpinning this hypothesis has come from the study of inflammation-related proteins in blood of individuals with mood disorders and schizophrenia. Significantly, recent data have emerged to suggest that changes in inflammation-related pathways are present in the CNS of subjects with psychiatric disorders. It is therefore timely to overview how such data, plus data on the role of inflammation-related proteins in CNS function, is contributing to understanding the pathophysiology of mood disorders and schizophrenia. In addition, it has been suggested that antidepressants, mood stabilizers and antipsychotic drugs act on inflammation-related pathways and therefore measuring levels of inflammation-related proteins in blood may be useful in monitoring treatment responsiveness. Despite these important neuropsychopharmacological discoveries, there is no clear understanding as to how inflammatory-related pathways can precipitate the onset of psychiatric symptoms. This review will focus on data suggesting that acute-reactive proteins and cytokines are affected by the pathophysiology of mood disorders and schizophrenia, that levels of blood inflammation-related proteins before and after treatment might be useful in the diagnosis of psychiatric disorders or measuring responsiveness to drug treatment. Finally, it will be postulated how changes in these proteins affect CNS function to cause psychiatric disorders.

Antidepressive effect of mirtazapine in post-myocardial infarction depression is associated with soluble TNF-R1 increase: data from the MIND-IT

BACKGROUND

Depressive disorder after myocardial infarction (MI) is associated with increased cardiac morbidity and mortality. Immune activity such as inflammation might be implicated as an underlying mechanism. The purpose of this study is to investigate whether the response to an antidepressant in post-MI depression is associated with changes of inflammatory markers in serum.

METHODS

In a double-blind placebo-controlled study with mirtazapine 30 mg/day (50 patients), the antidepressive effect was related to immune activation parameters. The cytokines interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), the soluble cytokine receptors sIL-6R, sTNF-R1 and sTNF-R2, and the inflammation-sensitive plasma proteins C-reactive protein and neopterin were assessed.

RESULTS

Subgroup analyses revealed a highly significant correlation of pronounced sTNF-R1 increase with a decrease in depressive symptoms in antidepressant responders.

CONCLUSION

Significant effects on inflammation accompany the therapeutic efficacy of mirtazapine in contrast to the therapeutic efficacy of placebo and the nontherapeutic efficacy of mirtazapine.

Immunity, aging, and geriatric depression

Inflammatory processes are likely to play a causal role in geriatric depression. Geriatric depression occurs in the context of illnesses in which inflammatory processes are part of the pathogenesis. Both aging and depression are associated with immune responses, and the connectivity among mood-regulating structures may be modulated by inflammatory responses. Geriatric depression exacerbates the symptoms of comorbid disorders. Geriatric depression often occurs in persons exposed to chronic stress, a state precipitating geriatric depression and triggering proinflammatory responses. The successful treatment of comorbid conditions that increase central nervous system inflammatory responses has general health benefits and should be part of clinical practice.

Efficacy and safety of Cerebrolysin in moderate to moderately severe Alzheimer's disease: results of a randomized, double-blind, controlled trial investigating three dosages of Cerebrolysin

BACKGROUND

cerebrolysin is a neuropeptide preparation mimicking the effects of neurotrophic factors. This subgroup analysis assessed safety and efficacy of Cerebrolysin in patients with moderate to moderately severe Alzheimer's disease (AD) (ITT data set: N = 133; MMSE: 14-20) included in a dose-finding study (ITT data set: N = 51; MMSE: 14-25). Results of the mild AD subgroup (ITT data set: N = 118; MMSE: 21-25) are also presented.

METHODS

patients with AD received 100 ml IV infusions of Cerebrolysin (10, 30 or 60 ml diluted in saline; N = 32, 34 and 35, respectively) or placebo (saline; N = 32) over twelve weeks (5 days per week for 4 weeks and 2 days per week for another 8 weeks). Primary efficacy criteria ADAS-cog+ (Alzheimer's Disease Assessment Scale Cognitive Subpart Modified) and CIBIC+ (Clinical Interview-based Impression of Change with Caregiver Input) were assessed 24 weeks after baseline.

RESULTS

at week 24, Cerebrolysin improved the global clinical function significantly with all three dosages and induced significant improvements in cognition, initiation of activities of daily living (ADL) and neuropsychiatric symptoms at 10-, 30- and 60-ml doses, respectively. Treatment effects on total ADL and other secondary parameters (MMSE, Trail-making test) were not significant. Cerebrolysin was safe and well tolerated.

CONCLUSIONS

these results demonstrate the efficacy of Cerebrolysin in moderate to moderately severe AD, showing dose-specific effects similar to those reported for patients with mild to moderate AD. The benefits of Cerebrolysin in advanced AD need to be confirmed in larger trials.

Sertoli cell therapy: a novel possible treatment strategy for treatment-resistant major depressive disorder

By the year 2020, depression will be the 2nd most common health problem in the world. Current medications to treat depression are effective in less than 50% of patients. There is the need for novel treatments for depression to address the high rates of resistance to current treatment and the chronic residual symptoms in many patients treated for depression. The heterogeneity of major depressive disorder suggests that multiple neurocircuits and neurochemicals are involved in its pathogenesis thus, finding an alternative to neurotransmitter agonist- or antagonist-based treatments offers an important new approach. Cellular therapy is an emerging treatment strategy for multiple diseases, including depression. Based upon their in vivo function as "nurse cells" within the testis and the documented viability, efficacy, and safety of Sertoli cells transplanted into multiple tissues, including brain, the potential for these cells to provide a neuroprotective, anti-inflammatory, and trophic environment for neurons should be considered. It is proposed that the combination of self-protective, immunoregulatory and trophic properties of Sertoli cells may confer a unique potential for depression treatment and avoid many of the risks and challenges associated with stem cell therapies. At the very least, studies of the effects of Sertoli cell transplantation will add substantially to our understanding of the cellular and molecular processes that underlie depression.

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.

Labile anger during interferon alfa treatment is associated with a polymorphism in tumor necrosis factor alpha

OBJECTIVE

Inflammatory cytokines may influence both labile anger and depression. Both psychiatric conditions can occur during interferon alfa-based treatments. Evidence also indicates a central nervous system role for tumor necrosis factor alpha (TNF-alpha), whose expression may be increased by interferon alfa. A polymorphism in the promoter region of TNF-alpha has been associated with various inflammatory illnesses. We therefore hypothesized that this TNF-alpha polymorphism would influence susceptibility to psychiatric symptoms during interferon alfa therapy.

METHODS

One hundred five patients with hepatitis C, initially without active major depression (major depressive disorder), were treated with interferon alfa and then prospectively monitored using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, the Beck Depression Inventory II, the Anger Irritability and Assault Questionnaire, and circulating TNF-alpha levels. The A-308G polymorphism (rs1800629) was determined using the 5'-nuclease assay. Repeated-measure mixed-effect analyses compared changes in symptoms over time.

RESULT

Beck Depression Inventory II score increased during interferon alfa therapy (F = 6.2; P < 0.001), with 27% developing MDD. The TNF-alpha A allele was associated with worsened labile anger (F = 2.5; P < 0.05) and fatigue (F = 2.9; P < 0.05) during treatment but not with major depression incidence (chi = 0.0; P = 0.99) or increased Beck Depression Inventory II (F = 1.2; P = 0.31). Labile anger was not predicted by the serotonin transporter polymorphism (F = 0.8; P = 0.59).

DISCUSSION

During treatment with an exogenous cytokine, vulnerability to worsening labile anger-distinct from major depression-is associated with genetic variability in TNF-alpha. This has implications both for patients being treated with interferon alfa and our understanding of genetic vulnerability for different subtypes of dysphoric and mood disorders.

Is glycogen synthase kinase-3 a central modulator in mood regulation?

Little is known regarding the mechanisms underlying the complex etiology of mood disorders, represented mainly by major depressive disorder and bipolar disorder. The 1996 discovery that lithium inhibits glycogen synthase kinase-3 (GSK3) raised the possibility that impaired inhibition of GSK3 is associated with mood disorders. This is now supported by evidence from animal biochemical, pharmacological, molecular, and behavioral studies and from human post-mortem brain, peripheral tissue, and genetic studies that are reviewed here. Mood disorders may result in part from impairments in mechanisms controlling the activity of GSK3 or GSK3-regulated functions, and disruptions of these regulating systems at different signaling sites may contribute to the heterogeneity of mood disorders. This substantial evidence supports the conclusion that bolstering the inhibitory control of GSK3 is an important component of the therapeutic actions of drugs used to treat mood disorders and that GSK3 is a valid target for developing new therapeutic interventions.

Effects of the probiotic Bifidobacterium infantis in the maternal separation model of depression

The concept that intestinal microbial composition not only affects the health of the gut, but also influences centrally-mediated systems involved in mood, is supported by a growing body of literature. Despite the emergent interest in brain-gut communication and its possible role in the pathogenesis of psychiatric disorders such as depression, particularly subtypes with accompanying gastrointestinal (GI) symptoms, there are few studies dedicated to the search for therapeutic solutions that address both central and peripheral facets of these illnesses. This study aims to assess the potential benefits of the probiotic Bifidobacterium infantis in the rat maternal separation (MS) model, a paradigm that has proven to be of value in the study of stress-related GI and mood disorders. MS adult rat offsprings were chronically treated with bifidobacteria or citalopram and subjected to the forced swim test (FST) to assess motivational state. Cytokine concentrations in stimulated whole blood samples, monoamine levels in the brain, and central and peripheral hypothalamic-pituitary-adrenal (HPA) axis measures were also analysed. MS reduced swim behavior and increased immobility in the FST, decreased noradrenaline (NA) content in the brain, and enhanced peripheral interleukin (IL)-6 release and amygdala corticotrophin-releasing factor mRNA levels. Probiotic treatment resulted in normalization of the immune response, reversal of behavioral deficits, and restoration of basal NA concentrations in the brainstem. These findings point to a more influential role for bifidobacteria in neural function, and suggest that probiotics may have broader therapeutic applications than previously considered.

Evolving refractory major depressive disorder diagnostic and treatment paradigms: toward closed-loop therapeutics

Current antidepressant therapies do not effectively control or cure depressive symptoms. Pharmaceutical therapies altogether fail to address an estimated 4 million Americans who suffer from a recurrent and severe treatment-resistant form of depression known as refractory major depressive disorder. Subjective diagnostic schemes, differing manifestations of the disorder, and antidepressant treatments with limited theoretical bases each contribute to the general lack of therapeutic efficacy and differing levels of treatment resistance in the refractory population. Stimulation-based therapies, such as vagus nerve stimulation, transcranial magnetic stimulation, and deep brain stimulation, are promising treatment alternatives for this treatment-resistant subset of patients, but are plagued with inconsistent reports of efficacy and variable side effects. Many of these problems stem from the unknown mechanisms of depressive disorder pathogenesis, which prevents the development of treatments that target the specific underlying causes of the disorder. Other problems likely arise due to the non-specific stimulation of various limbic and paralimbic structures in an open-loop configuration. This review critically assesses current literature on depressive disorder diagnostic methodologies, treatment schemes, and pathogenesis in order to emphasize the need for more stringent depressive disorder classifications, quantifiable biological markers that are suitable for objective diagnoses, and alternative closed-loop treatment options tailored to well-defined forms of the disorder. A closed-loop neurostimulation device design framework is proposed, utilizing symptom-linked biomarker abnormalities as control points for initiating and terminating a corrective electrical stimulus which is autonomously optimized for correcting the magnitude and direction of observed biomarker abnormality.

Fluoxetine and citalopram exhibit potent antiinflammatory activity in human and murine models of rheumatoid arthritis and inhibit toll-like receptors

OBJECTIVE

Selective serotonin reuptake inhibitors (SSRIs), in addition to their antidepressant effects, have been reported to have antiinflammatory effects. The aim of this study was to assess the antiarthritic potential of 2 SSRIs, fluoxetine and citalopram, in murine collagen-induced arthritis (CIA) and in a human ex vivo disease model of rheumatoid arthritis (RA).

METHODS

Following therapeutic administration of SSRIs, paw swelling was assessed and clinical scores were determined daily in DBA/1 mice with CIA. Joint architecture was examined histologically at the end of the treatment period. Cultures of human RA synovial membranes were treated with SSRIs, and cytokine production was measured. Toll-like receptor (TLR) function was examined in murine and human macrophages, human B cells, and human fibroblast-like synovial cells treated with SSRIs.

RESULTS

Both SSRIs significantly inhibited disease progression in mice with CIA, with fluoxetine showing the greatest degree of efficacy at the clinical and histologic levels. In addition, both drugs significantly inhibited the spontaneous production of tumor necrosis factor, interleukin-6, and interferon-gamma-inducible protein 10 in human RA synovial membrane cultures. Fluoxetine and citalopram treatment also inhibited the signaling of TLRs 3, 7, 8, and 9, providing a potential mechanism for their antiinflammatory action.

CONCLUSION

Fluoxetine and citalopram treatment selectively inhibit endosomal TLR signaling, ameliorate disease in CIA, and suppress inflammatory cytokine production in human RA tissue. These data highlight the antiarthritic potential of the SSRI drug family and provide further evidence of the involvement of TLRs in the pathogenesis of RA. The SSRIs may provide a template for potential antiarthritic drug development.

A psychoneuroimmunological review on cytokines involved in antidepressant treatment response

OBJECTIVES

The literature exploring the role that cytokine functioning plays in the pathogenesis and treatment of depressive illness is reviewed. The review focuses on the influence of antidepressants on cytokines, and on how treatment response might be affected by genetic variants of cytokines.

METHOD

The authors systematically reviewed the scientific literature on the subject over the last 20 years, searching PubMed, PsychInfo, and Cochrane databases.

RESULTS

Antidepressants modulate cytokine functioning, and these mechanisms appear to directly influence treatment outcome in depression. Antidepressants appear to normalize serum levels of major inflammatory cytokines, including interleukin (IL)-1beta, IL-6, tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma). Antidepressants are postulated to modulate cytokine functioning through their effects on intracellular cyclic adenosyl monophosphate (cAMP), serotonin metabolism, the hypothalamo-pituitary-adrenocortical (HPA) axis or through a direct action on neurogenesis. Preliminary research shows that cytokine genotypes and functioning may be able to help predict antidepressant treatment response.

CONCLUSIONS

Current literature demonstrates an association between antidepressant action and cytokine functioning in major depression. Improved understanding of the specific pharmacologic and pharmacogenetic mechanisms is needed. Such knowledge may serve to enhance our understanding of depression, leading to promising new directions in the pathology, nosology, and treatment of depression.

The effect of adalimumab on reducing depression symptoms in patients with moderate to severe psoriasis: a randomized clinical trial

BACKGROUND

Psoriasis is associated with health-related quality-of-life impairment and depression.

OBJECTIVE

We sought to determine the effect of adalimumab on depression symptoms in patients with psoriasis.

METHODS

Patients with moderate to severe psoriasis in a randomized, placebo-controlled, double-blind clinical trial were assessed for depression symptoms at baseline and week 12 or early termination (ET) using the Zung Self-rating Depression Scale (ZDS). The effects of adalimumab (40 mg every other week) versus placebo on ZDS score at week 12/ET were assessed using analysis of covariance. Relationships between ZDS and the Psoriasis Area and Severity Index (PASI), the Dermatology Life Quality Index, and the Short Form 36 Health Survey were assessed using Pearson correlations. Changes in ZDS score were compared for patients with and without a 75% or greater reduction in baseline PASI score.

RESULTS

Compared with the placebo group (n = 52), the adalimumab group (n = 44) experienced an additional 6-point reduction in ZDS score (95% confidence interval: 2.5-9.5; P < .001) by week 12/ET. Depression improvement was correlated with improvement in PASI (r = 0.5; P < .0001) and Dermatology Life Quality Index (r = 0.5; P < .0001). Greater ZDS score improvement was observed at week 12/ET in responders with a 75% or greater reduction in baseline PASI score than in nonresponders (10.6 [SD = 9.4] vs 1.4 [SD = 9.6]; P < .001).

LIMITATIONS

This analysis cannot distinguish whether adalimumab has a direct or indirect effect on depression.

CONCLUSIONS

Adalimumab treatment reduced psoriasis symptoms, reduced depression symptoms, and improved health-related quality of life in patients with moderate to severe psoriasis.

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.

Association between depressive symptoms and fibrosis markers: the Cardiovascular Health Study

OBJECTIVE

Fibrosis plays an important role in heart failure (HF) and other diseases that occur more frequently with increasing age. Depression is associated with an increased risk of heart failure and other age-related diseases. This study examined the association between depressive symptoms and fibrosis markers in adults aged 65 years and above.

METHODS

Fibrosis markers and depressive symptoms were assessed in 870 participants (age=80.9+/-5.9 yrs, 49% women) using a case-control design based on heart failure status (307 HF patients and 563 age- and sex-matched controls, of whom 284 with CVD risk factors (hypertension, diabetes mellitus, or hypercholesterolemia) and 279 controls without these CVD risk factors). Fibrosis markers were procollagen type I (PIP), type I collagen (CITP), and procollagen type III (PIIINP). Inflammation markers included C-reactive protein, white blood cell counts and fibrinogen. Depression was assessed using the Center for Epidemiological Studies-Depression (CES-D) scale using a previously validated cut-off point for depression (CES-D > or = 8). Covariates included demographic and clinical variables.

RESULTS

Depression was associated with higher levels of PIP (median=411.0, inter-quartile range (IQR)=324.4-472.7 ng/mL vs. 387.6, IQR=342.0-512.5 ng/mL, p=0.006) and CITP (4.99, IQR=3.53-6.85 vs. 4.53, IQR=3.26-6.22 microg/L, p=0.024), but not PIIIINP (4.07, IQR=2.75-5.54 microg/L vs. 3.58, IQR=2.71-5.01 microg/L, p=0.29) compared to individuals without depression. Inflammation markers were also elevated in depressed participants (CRP, p=0.014; WBC, p=0.075; fibrinogen, p=0.074), but these inflammation markers did not account for the relationship between depression and fibrosis markers.

CONCLUSIONS

Depression is associated with elevated fibrosis markers and may therefore adversely affect heart failure and other age-related diseases in which extra-cellular matrix formation plays a pathophysiological role.

Depression, traumatic stress and interleukin-6

BACKGROUND

Recent evidence indicates that various types of interactions between nervous and immune system are important in pathogenesis of depression. These findings show that a significant role in developing depression play pro-inflammatory cytokines that may mediate its psychological, and neurobiological manifestations. Great importance among these cytokine molecules plays interleukin-6 (IL-6). There is growing evidence that this inflammatory process related to depression may be influenced by psychological stress as well as organic inflammatory conditions. These findings suggest that specific influences related to traumatic stress and dissociation could be found in close relationship to increased level of cytokine IL-6.

METHODS

In the present study we have performed psychometric measurement of depression (BDI-II), traumatic stress symptoms (TSC-40) and dissociation (DES, SDQ-20), and immunochemical measure of serum IL-6 in 40 inpatients with unipolar depression (mean age 42.3+/-6.8).

RESULTS

The results show that IL-6 is significantly correlated to BDI-II (Spearman R=0.47, p<0.01), TSC-40 (Spearman R=0.32, p<0.05), SDQ-20 (Spearman R=0.34, p<0.05) but not to DES (Spearman R=0.25, p=0.11).

CONCLUSION

The findings of the present study indicate that increased level of IL-6 in depression could be directly related to symptoms of traumatic stress and somatoform dissociation.