Illness, cytokines, and depression

Functional biomarkers of depression: diagnosis, treatment, and pathophysiology

Major depressive disorder (MDD) is a heterogeneous illness for which there are currently no effective methods to objectively assess severity, endophenotypes, or response to treatment. Increasing evidence suggests that circulating levels of peripheral/serum growth factors and cytokines are altered in patients with MDD, and that antidepressant treatments reverse or normalize these effects. Furthermore, there is a large body of literature demonstrating that MDD is associated with changes in endocrine and metabolic factors. Here we provide a brief overview of the evidence that peripheral growth factors, pro-inflammatory cytokines, endocrine factors, and metabolic markers contribute to the pathophysiology of MDD and antidepressant response. Recent preclinical studies demonstrating that peripheral growth factors and cytokines influence brain function and behavior are also discussed along with their implications for diagnosing and treating patients with MDD. Together, these studies highlight the need to develop a biomarker panel for depression that aims to profile diverse peripheral factors that together provide a biological signature of MDD subtypes as well as treatment response.

Acute amygdaloid response to systemic inflammation

The amygdala, a group of nuclei located in the medial temporal lobe, is a key limbic structure involved in mood regulation, associative learning, and modulation of cognitive functions. Functional neuroanatomical studies suggest that this brain region plays also an important role in the central integration of afferent signals from the peripheral immune system. In the present study, intracerebral electroencephalography and microdialysis were employed to investigate the electrophysiological and neurochemical consequences of systemic immune activation in the amygdala of freely moving rats. Intraperitoneal administration of bacterial lipopolysaccharide (100 μg/kg) induced with a latency of about 2 h a significant increase in amygdaloid neuronal activity and a substantial rise in extracellular noradrenaline levels. Activated neurons in the amygdaloid complex, identified by c-Fos immunohistochemistry, were mainly located in the central nucleus and, to a lesser extent, in the basolateral nucleus of the amygdala. Gene expression analysis in micropunches of the amygdala revealed that endotoxin administration induced a strong time-dependent increase in IL-1β, IL-6, and TNF-α mRNA levels indicating that these cytokines are de novo synthesized in the amygdala in response to peripheral immune activation. The changes in amygdaloid activity were timely related to an increase in anxiety-like behavior and decreased locomotor activity and exploration in the open-field. Taken together, these data give novel insights into different features of the acute amygdaloid response during experimental inflammation and provides further evidence that the amygdala integrates immune-derived information to coordinate behavioral and autonomic responses.

Combination of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 reduces post-myocardial infarction depression symptoms and restores intestinal permeability in a rat model

Myocardial infarction (MI) in rats is accompanied by apoptosis in the limbic system and a behavioural syndrome similar to models of depression. We have already shown that probiotics can reduce post-MI apoptosis and designed the present study to determine if probiotics can also prevent post-MI depressive behaviour. We also tested the hypothesis that probiotics achieve their central effects through changes in the intestinal barrier. MI was induced in anaesthetised rats via 40-min transient occlusion of the left anterior coronary artery. Sham rats underwent the same surgical procedure without actual coronary occlusion. For 7 d before MI and between the seventh post-MI day and euthanasia, half the MI and sham rats were given one billion live bacterial cells of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 per d dissolved in water, while the remaining animals received only the vehicle (maltodextrin). Depressive behaviour was evaluated 2 weeks post-MI in social interaction, forced swimming and passive avoidance step-down tests. Intestinal permeability was evaluated by oral administration with fluorescein isothiocyanate-dextran, 4 h before euthanasia. MI rats displayed less social interaction and impaired performance in the forced swimming and passive avoidance step-down tests compared to the sham controls (P < 0·05). Probiotics reversed the behavioural effects of MI (P < 0·05), but did not alter the behaviour of sham rats. Intestinal permeability was increased in MI rats and reversed by probiotics. In conclusion, L. helveticus R0052 and B. longum R0175 combination interferes with the development of post-MI depressive behaviour and restores intestinal barrier integrity in MI rats.

Early parental loss and depression history: associations with recent life stress in major depressive disorder

Although exposure to early adversity and prior experiences with depression have both been associated with lower levels of precipitating life stress in depression, it is unclear whether these stress sensitization effects are similar for all types of stress or whether they are specific to stressors that may be particularly depressogenic, such as those involving interpersonal loss. To investigate this issue, we administered structured, interview-based measures of early adversity, depression history, and recent life stress to one hundred adults who were diagnosed with major depressive disorder. As predicted, individuals who experienced early parental loss or prolonged separation (i.e., lasting one year or longer) and persons with more lifetime episodes of depression became depressed following lower levels of life stress occurring in the etiologically-central time period of three months prior to onset of depression. Importantly, however, additional analyses revealed that these effects were unique to stressors involving interpersonal loss. These data highlight potential stressor-specific effects in stress sensitization and demonstrate for the first time that individuals exposed to early parental loss or separation, and persons with greater histories of MDD, may be selectively sensitized to stressors involving interpersonal loss.

Depressive-like behavior induced by tumor necrosis factor-α in mice

Pro-inflammatory cytokines are implicated in the pathogenesis of depression. However, few animal models of cytokine-induced depression well characterized regarding its response to antidepressants are available. Hence, the aim of this study was to propose a model of depressive-like behavior induced by the administration of tumor necrosis factor-α (TNF-α) responsive to antidepressant treatments. TNF-α administered by i.c.v. route produced a depressive-like behavior in the forced swimming test (FST) and tail suspension test (TST) (0.1-1 fg/site and 0.001 fg/site, respectively), without altering the locomotor activity in the open-field test. In addition, anti-TNF-α antibody (0.1-1 pg/site, i.c.v.), but not the inhibitor of TNF-α synthesis thalidomide (3-30 mg/kg, s.c.) produced an antidepressant-like response in the FST. Moreover, either anti-TNF-α antibody (0.01 pg/site, i.c.v) or thalidomide (30 mg/kg, s.c.) reversed the depressive-like behavior induced by TNF- (0.1 fg/site, i.c.v.) in the FST. TNF-α receptor 1 (TNFR1) knockout mice exhibited an antidepressant-like behavior in the FST and in the TST as compared with the wild type mice. Treatment with fluoxetine (32 mg/kg, i.p), imipramine (15 mg/kg, i.p.) and desipramine (16 mg/kg, i.p) prevented the depressant-like effect induced by TNF-α (0.1 fg/site, i.c.v.) in the FST. In addition, TNF-α (0.1 fg/site, i.c.v.) administration produced an anhedonic response in a sucrose intake test, which was prevented by anti-TNF-α antibody (0.01 pg/site, i.c.v) or fluoxetine (32 mg/kg, i.p). Taken together, these results indicate that TNF-α produces a depressive-like state in mice, reinforcing the notion that an inflammatory component may play an important role in the pathophysiology of depression and suggesting that the central administration of TNF-α may be a novel approach to study the inflammatory component of depressive disorder. This article is part of a Special Issue entitled 'Anxiety and Depression'.

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.

Cytokines mediated inflammation and decreased neurogenesis in animal models of depression

In patients with major depression or in animal models of depression, significantly increases in the concentrations of pro-inflammatory cytokines have been consistently reported. Proinflammatory cytokines can stimulate the hypothalamic-pituitary-adrenal (HPA) axis to release stress hormone, glucocorticoids. As a consequence of excessive inflammatory response triggered by pro-inflammatory cytokines in the periphery, free radicals, oxidants and glucocorticoids are over-produced, which can affect glial cell functions and damage neurons in the brain. Indeed, decreased neurogenesis and the dysfunction of neurotrophic system (up- or down-regulations of neurotrophins and their receptors) have been recently found. Effective treatments for depressive symptoms, such as antidepressants and omega-3 fatty acids can increase or modulate neurotrophic system and enhance neurogenesis. However, the relationship between glial cells; microglia (mostly involved in neuroinflammation) and astrocytes (producing neurotrophins), and the contribution of inflammation to decreased neurogenesis and dysfunction of neurotrophic system are almost unknown. This review first introduces changes in behavior, neurotransmitter, cytokine and neurogenesis aspects in depressed patients and several animal models of depression, secondly explores the possible relationship between pro- and anti-inflammatory cytokines and neurogenesis in these models, then discusses the effects of current treatments on inflammation, neurotrophic system and neurogenesis, and finally pointes out the limitations and future research directions.

Interleukin-1 receptor activation by systemic lipopolysaccharide induces behavioral despair linked to MAPK regulation of CNS serotonin transporters

Serotonin (5-hydroxytryptamine, 5-HT) has long been implicated in regulation of mood. Medications that block the neuronal 5-HT transporter (SERT) are used as major pharmacological treatment for mood disorders. Conversely, stimuli that enhance SERT activity might be predicted to diminish synaptic 5-HT availability and increase the risk for 5-HT-related CNS disorders. We have shown that the inflammatory cytokines enhance brain SERT activity in cultured serotonergic cells and nerve terminal preparations in vitro. In this study, we establish that intraperitoneal injection of the cytokine-inducer lipopolysaccharide (LPS) stimulates brain SERT activity, acting at doses below those required to induce overt motor suppression. SERT stimulation by LPS is paralleled by increased immobility in both the tail suspension test (TST) and the forced swim test (FST); antidepressant-sensitive alterations are thought to model aspects of behavioral despair. Both the stimulation of SERT activity and induced immobility are absent when LPS is administered to interleukin-1 receptor (IL-1R)-deficient mice and in the presence of SB203580, an inhibitor of IL-1R-stimulated p38 MAPK. Moreover, the ability of LPS to enhance immobility in TST is lost in SERT knockout mice. These findings reveal an ability of peripheral inflammatory stimuli to enhance brain SERT activity through IL-1R and p38 MAPK pathways in vivo and identify a requirement for SERT expression in immune-system-modulated despair behaviors. Our studies identify IL-1R- and p38 MAPK-dependent regulation of SERT as one of the mechanisms by which environmentally driven immune system activation can trigger despair-like behavior in an animal model, encouraging future analysis of the pathway for risk factors in neuropsychiatric disorders.

Stimulated gene expression profiles as a blood marker of major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a moderately heritable disorder with a high lifetime prevalence. At present, laboratory blood tests to support MDD diagnosis are not available.

METHODS

We used a classifier approach on blood gene expression profiles of a unique set of unmedicated subjects (MDD patients and control subjects) to select genes with expression predictive for disease status. To reveal blood gene expression changes related to major depressive disorder-disease, we applied a powerful ex vivo stimulus to the blood: incubation with lipopolysaccharide (LPS; 10 ng/mL blood).

RESULTS

Based on LPS-stimulated blood gene expression using whole-genome microarrays (primary cohort; 21 MDD patients, 21 healthy control subjects), we identified a set of genes (CAPRIN1, CLEC4A, KRT23, MLC1, PLSCR1, PROK2, ZBTB16) that serves as a molecular signature of MDD. These findings were validated using an independent quantitative polymerase chain reaction method (primary cohort, p = .007). The difference between depressive patients and control subjects was confirmed (p = .019) in a replication cohort of 13 MDD patients and 14 control subjects. The MDD signature score comprised expression levels of seven genes could discriminate depressive patients from control subjects with sensitivity of 76.9% and specificity of 71.8%.

CONCLUSIONS

We have shown for the first time that molecular analysis of stimulated blood cells can be used as an endophenotype for MDD diagnosis, which is a milestone in establishing biomarkers for neuropsychiatric disorders with moderate heritability in general. Our results may provide a new entry point for following and predicting treatment outcome, as well as prediction of severity and recurrence of major depressive disorder.

Metabolic syndrome abnormalities are associated with severity of anxiety and depression and with tricyclic antidepressant use

OBJECTIVE

The metabolic syndrome (MetSyn) predisposes to cardiovascular disease and diabetes mellitus. There might also be an association between the MetSyn and anxiety and depression, but its nature is unclear. We aimed to investigate whether diagnosis, symptom severity and antidepressant use are associated with the MetSyn.

METHOD

We addressed the odds for the MetSyn and its components among 1217 depressed and/or anxious subjects and 629 controls, and their associations with symptom severity and antidepressant use.

RESULTS

Symptom severity was positively associated with prevalence of the MetSyn, [adjusted odds ratio (OR) 2.21 for very severe depression: 95% confidence interval (CI): 1.06-4.64, P = 0.04], which could be attributed to abdominal obesity and dyslipidemia. Tricyclic antidepressant (TCA) use also increased odds for the MetSyn (OR 2.30, 95% CI: 1.21-4.36, P = 0.01), independent of depression severity.

CONCLUSION

The most severely depressed people and TCA users more often have the MetSyn, which is driven by abdominal adiposity and dyslipidemia.

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.

Neuroinflammation and cognitive aging

Cognitive aging describes the changes in mental abilities that occur with increasing age. Although experts disagree on the core underlying processes involved, one factor that links many factors associated with cognitive aging is neuroinflammation. Markers of inflammation are associated directly with deficits in cognitive function and with diseases that are risk factors for cognitive decline. Neuroinflammation is also associated with depression and may account for the complex interaction of depression and cognition in older adults. Interventions that reduce inflammation may improve cognition. Understanding how neuroinflammation affects cognition may provide directions for useful interventions to prevent or treat cognitive decline in older adults.

Black sheep get the blues: a psychobiological model of social rejection and depression

Major life events involving social rejection are strongly associated with onset of depression. To account for this relation, we propose a psychobiological model in which rejection-related stressors elicit a distinct and integrated set of cognitive, emotional, and biological changes that may evoke depression. In this model, social rejection events activate brain regions involved in processing negative affect and rejection-related distress (e.g., anterior insula, dorsal anterior cingulate cortex). They also elicit negative self-referential cognitions (e.g., "I'm undesirable," "Other people don't like me") and related self-conscious emotions (e.g., shame, humiliation). Downstream biological consequences include upregulation of the hypothalamic-pituitary-adrenal axis, sympathetic-adrenal-medullary axis, and inflammatory response. Pro-inflammatory cytokines play an important role in this process because they induce a constellation of depressotypic behaviors called sickness behaviors. Although these changes can be short-lived, sustained inflammation may occur via glucocorticoid resistance, catecholamines, sympathetic innervation of immune organs, and immune cell aging. This response also may be moderated by several factors, including prior life stress, prior depression, and genes implicated in stress reactivity.

Cardiovascular abnormalities in patients with major depressive disorder: autonomic mechanisms and implications for treatment

This article provides a detailed review of the association of major depression with coronary heart disease (CHD), examines the biological variables underpinning the linkage and discusses the clinical implications for treatment. When considering the co-morbidity between major depressive disorder (MDD) and CHD it is important to differentiate between (i) the prevalence and impact of MDD in those with existing CHD and (ii) MDD as a risk factor for the development of CHD. Whether the same biological mechanisms are at play in these two instances remains unknown. Depression is common in patients with CHD. Importantly, depression in these patients increases mortality. There is also consistent evidence that MDD is a risk factor for the development of CHD. The relative risk of developing CHD is proportional to the severity of depression and is independent of smoking, obesity, hypercholesterolaemia, diabetes mellitus and hypertension. There is a clear need to identify the underlying neurochemical mechanisms responsible for MDD and their linkage to the heart and vascular system. Of particular interest are activation of stress pathways, including both the sympathetic nervous system and hypothalamic-pituitary-adrenal axis, and inflammatory-mediated atherogenesis. Elevated sympathetic activity, reduced heart rate variability and increased plasma cortisol levels have been documented in patients with MDD. In addition to direct effects on the heart and vasculature, activation of stress pathways may also be associated with increased release of inflammatory cytokines such as interleukin-6 and tumour necrosis factor-alpha. Elevated levels of C-reactive protein are commonly observed in patients with MDD. The majority of investigations examining treatment of depression following myocardial infarction have focused on safety and efficacy; there is little evidence to indicate that treating depression in these patients improves survival. Given that strategies for preventive therapy remain incompletely formulated, future research should focus on generating a better understanding of the neurobiology of MDD and heart disease as a basis for rational and effective therapy.

Neurobiological trait abnormalities in bipolar disorder

Dissecting trait neurobiological abnormalities in bipolar disorder (BD) from those characterizing episodes of mood disturbance will help elucidate the aetiopathogenesis of the illness. This selective review highlights the immunological, neuroendocrinological, molecular biological and neuroimaging abnormalities characteristic of BD, with a focus on those likely to reflect trait abnormalities by virtue of their presence in euthymic patients or in unaffected relatives of patients at high genetic liability for illness. Trait neurobiological abnormalities of BD include heightened pro-inflammatory function and hypothalamic-pituitary-adrenal axis dysfunction. Dysfunction in the intracellular signal transduction pathway is indicated by elevated protein kinase A activity and altered intracellular calcium signalling. Consistent neuroimaging abnormalities include the presence of ventricular enlargement and white matter abnormalities in patients with BD, which may represent intermediate phenotypes of illness. In addition, spectroscopy studies indicate reduced prefrontal cerebral N-acetylaspartate and phosphomonoester concentrations. Functional neuroimaging studies of euthymic patients implicate inherently impaired neural networks subserving emotional regulation, including anterior limbic, ventral and dorsal prefrontal regions. Despite heterogeneous samples and conflicting findings pervading the literature, there is accumulating evidence for the existence of neurobiological trait abnormalities in BD at various scales of investigation. The aetiopathogenesis of BD will be better elucidated by future clinical research studies, which investigate larger and more homogenous samples and employ a longitudinal design to dissect neurobiological abnormalities that are underlying traits of the illness from those related to episodes of mood exacerbation or pharmacological treatment.

An evolutionary hypothesis of depression and its symptoms, adaptive value, and risk factors

Major depression is an evolutionary paradox: it carries great disadvantages for survival and reproduction of both patients and their relatives, yet it is common and has significant heritability. We propose a new hypothesis to help explain many of depression's symptoms and its risk factors, most of them not explained by previous evolutionary theories. We hypothesize that the evolutionary costs of depression are offset by its benefits in combating existing infections and avoiding new ones. As our hypothesis predicts, depression can be elicited by various infections as well as by environmental stressors that compromise immune function. Moreover, many depressive symptoms tend to aid immune function and reduce exposure to new infections and stressors. The hypothesis makes many predictions about the epidemiology and physiology of depression that are supported by available evidence. The hypothesis also suggests that possible underlying infectious and immune factors deserve greater consideration in prevention and treatment of depression.

Age and neuroinflammation: a lifetime of psychoneuroimmune consequences

Aging can impair functional interaction that occurs between the brain and the immune system. Recent findings indicate that microglia and astrocytes, innate immune cells of the brain, become more reactive during normal aging. This age-associated increase in innate immune reactivity sets the stage for an exaggerated inflammatory cytokine response in the brain after activation of the peripheral innate immune system. This elevated neuroinflammatory response may lead to more severe long-lasting behavioral and cognitive deficits. This article discusses new evidence that aging creates a brain environment that is permissive to the occurrence of mental health complications following innate immune activation.

Psychoneuroimmune implications of type 2 diabetes: redux

A sizable body of knowledge has arisen demonstrating that type 2 diabetes (T2D) is associated with alterations in the innate immune system. The resulting proinflammatory-leaning imbalance is implicated in the development of secondary disease complications and comorbidities, such as delayed wound healing, accelerated progress of atherosclerosis, and retinopathy, in people who have T2D. New experimental data and the results of recently published health-related quality-of-life surveys indicate that individuals who have T2D experience diminished feelings of happiness, well being, and satisfaction with life. These emotional and psychological consequences of T2D point to altered neuroimmunity as a previously unappreciated complication of T2D. This article discusses recent data detailing the impact of T2D on a person's PNI response.

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.

Immune system dysregulation in adolescent major depressive disorder

BACKGROUND

A large body of evidence suggests that immune system dysregulation is associated with Major Depressive Disorder (MDD) in adults. This study extends this work to adolescent MDD to examine the hypotheses of immune system dysregulation in adolescents with MDD, as manifested by significantly: (i) elevated plasma levels of cytokines (interferon [IFN]-gamma, tumor necrosis factor-alpha, interleukin [IL]-6, IL-1beta, and IL-4); and (ii) Th1/Th2 cytokine imbalance shifted toward Th1 as indexed by increased IFN-gamma/IL-4.

METHOD

Thirty adolescents with MDD (19 females; 13 medication-free/naïve; ages 12-19) of at least 6 weeks duration and a minimum severity score of 40 on the Children's Depression Rating Scale-Revised, and 15 healthy comparisons (8 females), group-matched for age, were enrolled. Plasma cytokines were examined using enzyme-linked immunosorbent assay. Mann-Whitney test was used to compare subjects with MDD and controls.

RESULTS

Adolescents with MDD had significantly elevated plasma IFN-gamma levels (3.38+/-11.8 pg/ml versus 0.37+/-0.64 pg/ml; p<0.003), and IFN-gamma/IL-4 ratio (16.6+/-56.5 versus 1.76+/-2.28; p=0.007). A trend for IL-6 to be elevated in the MDD group was also observed (1.52+/-2.88 pg/ml versus 0.49+/-0.90 pg/ml; p=0.09). Importantly, findings remained evident when medicated subjects were excluded.

CONCLUSIONS

Findings suggest that immune system dysregulation may be associated with adolescent MDD, with an imbalance of Th1/Th2 shifted toward Th1, as documented in adult MDD. Larger studies with medication-free adolescents should follow.

IL-10 modulates depressive-like behavior

The role of pro-inflammatory cytokines in psychiatric disorders has been the focus of great research attention in recent years. Paradoxically, the same is not true for anti-inflammatory cytokines. In the present study, we assessed the behavioral profile of animals with altered expression of the anti-inflammatory cytokine IL-10. We performed a battery of tests to assess anxiety, depressive-like and cognitive behaviors in mice overexpressing IL-10 (PMT10) and IL-10(-/-) animals; in the later mice we also tested the behavioral effect of IL-10 administration. In the forced-swimming test, IL-10(-/-) females displayed increased depressive-like behavior; importantly, this phenotype was reverted by the injection of IL-10. Moreover, mice overexpressing IL-10 presented a decreased depressive-like behavior. Despite the presence of a similar trend, male animals did not reach significant differences in depressive-like behavior. Assessment in the open-field showed that the absence of IL-10 decreased the percentage of time spent in the center of the arena in both male and female mice, while male animals overexpressing IL-10 revealed an opposite behavior. For both sexes, imbalance in IL-10 levels did not affect spatial reference memory. In conclusion, variations in IL-10 expression are associated with an altered depressive-like behavior, but do not influence cognitive performance. Interestingly, IL-10 imbalance produced more profound behavioral changes in females than in male animals. This is in accordance with clinical data demonstrating an increased susceptibility of women to mood disorders, suggesting an interplay between anti-inflammatory cytokines and sexual steroids.

Depression: an important comorbidity with metabolic syndrome in a general population

OBJECTIVE

There is a recognized association among depression, diabetes, and cardiovascular disease. The aim of this study was to examine in a sample representative of the general population whether depression, anxiety, and psychological distress are associated with metabolic syndrome and its components.

RESEARCH DESIGN AND METHODS

Three cross-sectional surveys including clinical health measures were completed in rural regions of Australia during 2004-2006. A stratified random sample (n = 1,690, response rate 48%) of men and women aged 25-84 years was selected from the electoral roll. Metabolic syndrome was defined by the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults, Adult Treatment Panel III (NCEP ATP III), and International Diabetes Federation (IDF) criteria. Anxiety and depression were assessed by the Hospital Anxiety and Depression Scale and psychological distress by the Kessler 10 measure.

RESULTS

Metabolic syndrome was associated with depression but not psychological distress or anxiety. Participants with the metabolic syndrome had higher scores for depression (n = 409, mean score 3.41, 95% CI 3.12-3.70) than individuals without the metabolic syndrome (n = 936, mean 2.95, 95% CI 2.76-3.13). This association was also present in 338 participants with the metabolic syndrome and without diabetes (mean score 3.37, 95% CI 3.06-3.68). Large waist circumference and low HDL cholesterol showed significant and independent associations with depression.

CONCLUSIONS

Our results show an association between metabolic syndrome and depression in a heterogeneous sample. The presence of depression in individuals with the metabolic syndrome has implications for clinical management.

How does immune challenge inhibit ingestion of palatable food? Evidence that systemic lipopolysaccharide treatment modulates key nodal points of feeding neurocircuitry

Immune challenge induces behavioral changes including reduced ingestion of palatable food. Multiple pathways likely contribute to this effect, including viscerosensory pathways controlling hypothalamic feeding circuits or by influence on "reward" circuitry previously established to control ingestive behavior. To investigate whether the effects of immune challenge may influence this network, we compared brain activation patterns in animals trained to drink a palatable sweetened milk solution and treated systemically with either the immune stimulant lipopolysaccharide (LPS) or saline. Brain sections were processed for localization of the activation marker c-Fos in neurons of regions implicated in regulation of feeding behavior. Sweetened milk ingestion was associated with increased numbers of c-Fos positive neurons in the caudal core and shell of the nucleus accumbens (NAc), the paraventricular thalamus (PVT), central nucleus of the amygdala (CEA), the basal lateral amygdala (BLA), in orexin-A containing neurons of the lateral hypothalamus (LH), and in cocaine and amphetamine regulated transcript (CART) neurons of the arcuate hypothalamus. In LPS-treated animals sweetened milk consumption was significantly reduced, as was c-Fos induction in the hypothalamic orexin-A and CART neurons, and in the BLA. In addition, induction of c-Fos in the rostral regions of the NAc, the PVT, and CEA was increased following LPS treatment, compared to controls. The findings from this study point to a network of brain regions (LH, PVT, NAc, and BLA) previously implicated in the modulation of feeding behavior, reward, and arousal that may also contribute to neural substrates involved in the reorganization of behavioral priorities that occurs during sickness.

Relationships among endocrine and signaling-related responses to antidepressants in human monocytic U-937 blood cells: analysis of factors and response patterns

OBJECTIVE

Antidepressants (AD) (desipramine, imipramine, maprotiline, mirtazapine) and corticosteroid (CS) were examined for their effects on gene expression in human monocytic U-937 blood cells. Endocrine and signaling-related response patterns were determined by expression analysis of different factors, comprising endocrine (glucocorticoid receptor [GR], GR-alpha/beta/gamma; mineralocorticoid receptor [MR]) and signaling-related pathways (p105, STAT3, c-jun, c-fos, JNK1, GAPDH, TNF-alpha).

METHODS

A semiquantitative RT-PCR for factor responses after 24 h of treatment was conducted and exploratory multivariate statistical procedures were applied for further analysis.

RESULTS

Compared to controls, significant reduction of mRNA levels of GR-beta under imipramine and of c-jun under desipramine treatment were found. CS treatment significantly reduced mRNA levels of GR-alpha/beta, TNF-alpha, p105 and c-jun compared to controls. Compared to CS treatment, significantly increased mRNA levels were found for JNK1 under imipramine treatment and for GR-alpha after treatment with all AD examined.

DISCUSSION

The multivariate approach meets the requirements of the complex situation of metabolic reactions induced by AD or CS treatment. Our data show that AD affect both, endocrine and signaling-related factors in human monocytic U-937 blood cells, although clearly not in a uniform manner. Hereby, GR is obviously playing a comparably central role. Overall, AD treatment might indeed normalize deviations of cellular endocrine and signaling-related pathways in major depressive disorder via the mechanisms examined.

Burden of depression among impoverished HIV-positive women in Peru

OBJECTIVES

In resource-poor settings, the mental health burden among HIV-positive women is exacerbated by poverty. We sought to describe the extent, risk factors, and experience of depression among impoverished HIV-positive women living in Lima, Peru.

METHODS

This is a case series of 78 HIV-positive women in Lima, Peru. We measured depression, stigma, and social support and performed a multivariable analysis to identify factors associated with depression.

RESULTS

Among 78 HIV-positive patients, 68% were depressed. Depression and suicidal ideation were rarely diagnosed by providers. In multivariable analysis, HIV-related stigma and food scarcity were associated with depression.

CONCLUSIONS

In our cohort of HIV-positive women in Lima, Peru, poverty and socioeconomic vulnerability contributed to depression. Findings highlight the heavy burden of depression in this cohort of poor women and the need to incorporate mental health services as an integral component of HIV care.

Intrahippocampal transplantation of transgenic neural precursor cells overexpressing interleukin-1 receptor antagonist blocks chronic isolation-induced impairment in memory and neurogenesis

The proinflammatory cytokine interleukin-1 (IL-1) within the brain is critically involved in mediating the memory impairment induced by acute inflammatory challenges and psychological stress. However, the role of IL-1 in memory impairment and suppressed neurogenesis induced by chronic stress exposure has not been investigated before now. We report here that mice that were isolated for 4 weeks displayed a significant elevation in hippocampal IL-1beta levels concomitantly with body weight loss, specific impairment in hippocampal-dependent memory, and decreased hippocampal neurogenesis. To examine the causal role of IL-1 in these effects, we developed a novel approach for long-term delivery of IL-1 receptor antagonist (IL-1ra) into the brain, using transplantation of neural precursor cells (NPCs), obtained from neonatal mice with transgenic overexpression of IL-1ra (IL-1raTG) under the glial fibrillary acidic protein promoter. Four weeks following intrahippocampal transplantation of IL-1raTG NPCs labeled with PKH-26, the transplanted cells were incorporated within the dentate gyrus and expressed mainly astrocytic markers. IL-1ra levels were markedly elevated in the hippocampus, but not in other brain regions, by 10 days and for at least 4 weeks post-transplantation. Transplantation of IL-1raTG NPCs completely rescued the chronic isolation-induced body weight loss, memory impairment, and suppressed hippocampal neurogenesis, compared with isolated mice transplanted with WT cells or sham operated. The transplantation had no effect in group-housed mice. These findings elucidate the role of IL-1 in the pathophysiology of chronic isolation and suggest that transplantation of IL-1raTG NPCs may provide a useful therapeutic procedure for IL-1-mediated memory disturbances in chronic inflammatory and neurological conditions.

Fatigue in patients with advanced cancer: a pilot study of an intervention with infliximab

GOALS OF WORK

The objective of this study was to determine the effect of infliximab, an antitumor necrosis factor alpha (TNFalpha) antibody, on fatigue in patients with advanced cancer.

MATERIALS AND METHODS

This was a pilot study undertaken in a specialist palliative care unit. Seventeen eligible outpatients were enrolled in this study. Infliximab 5 mg/kg was administered intravenously at baseline and if there was observable clinical benefit, every 4 weeks thereafter until clinical benefit was lost. The primary outcome measure assessing subjective functional improvement was the change in fatigue severity scale (FSS) score at 4 weeks following an infliximab infusion. Secondary outcome measures of subjective functional improvement that were assessed 4 weeks after each infliximab infusion included changes in Karnofsky performance status (KPS), hospital anxiety and depression scale (HADS) score, anxiety and depression subscores, and appetite visual analogue scale. Clinical laboratory assessments were C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), TNFalpha, interleukin-6, and leptin concentrations.

MAIN RESULTS

At week 4, 9 of 14 patients improved in FSS, 3 of 15 improved in KPS, 7 of 15 improved in total HADS and the majority had modest improvements in serum CRP, ESR, or leptin concentrations. Case studies of six patients with overall improvement are described in detail. Five serious adverse events occurred; two were serious infections possibly related to treatment.

CONCLUSIONS

A subgroup of patients in this small pilot study demonstrated uniform subjective/clinical benefit. We were not able to identify any predictors of this response; a larger, controlled study may reveal more information.

Peritoneal inflammation and fatigue experiences following colorectal surgery: a pilot study

OBJECTIVE

The effect of post-surgical inflammation, as indicated by peritoneal cytokines and neopterin, was assessed on the duration and characteristics of post-surgical fatigue (PSF) experiences.

BACKGROUND

During the weeks following major colorectal surgery, many patients report experiencing substantial fatigue but the physiological factors contributing to this are not well understood. Because cytokines, particularly pro-inflammatory cytokines, have been found to be important in fatigue-related experiences in experimental systems, they may well be important mediators of PSF.

METHODS

In 27 patients following colorectal surgery, cytokines and neopterin (a relatively stable immune activation marker) were measured in 24-h peritoneal drain fluid and in serum 2, 5 and 14 days post-operatively. Patient fatigue was assessed using the Identity-Consequence Fatigue Scale questionnaire pre-operatively and 2, 5, 14, 30 and 60 days after surgery.

RESULTS

Using linear mixed model analysis controlling for age, gender and ASA score, the trajectory of fatigue experience during the first 2 months of surgical recovery was significantly related to intra-peritoneal concentrations of IL-6, IL-10 and TNF-alpha during the first 24h after surgery, while the trajectory of fatigue impacts was related only to IL-6 and TNF-alpha concentrations. Moreover, correlations between neopterin, and post-operative peritoneal (within 24h of surgery) and serum cytokine concentrations permitted neopterin to be used as a surrogate inflammation marker. Patients with elevated neopterin concentrations during the initial weeks following surgery reported significantly more severe and sustained PSF.

CONCLUSIONS

Locally occurring inflammatory responses may influence reports of fatigue following major surgery in a sustained manner, and, as a consequence, reducing inflammation may be effective in reducing PSF.

Cytokines and cholinergic signals co-modulate surgical stress-induced changes in mood and memory

Inflammatory cytokines and the cholinergic system have been implicated in the effects of stressors on mood and memory; however, the underlying mechanisms involved and the potential interrelationships between these pathways remain unclear. To address these questions, we administered neuropsychological tests to 33 generally healthy surgery patients who donated blood samples several days prior to undergoing moderate surgery (baseline), on the morning of the surgery (i.e., a psychological stressor), and one day after surgery. Eighteen control subjects were similarly tested. Serum levels of inflammatory cytokines, acetylcholinesterase (AChE) activity, and the stressor-inducible AChE-R variant were measured. An elevation in anxiety levels, an increase in depressed mood, and a decline in declarative memory were observed on the morning of the surgery, prior to any medical intervention, and were exacerbated one day after surgery. The surgical stressor-induced elevated IL-1 beta levels, which contributed to the increased depressed mood and to the post-surgery increase in AChE-R expression. The latter increase, which was also predicted by pre-surgery AChE-R and post-surgery mood disturbances, was associated with exacerbated memory impairments induced by surgery. In addition, elevated levels of AChE-R on the morning of the surgery predicted the post-surgery elevation in IL-6 levels, which was associated with amelioration of the memory impairments induced by surgery. Taken together, these findings suggest that exposure to a surgical stressor induces a reciprocal up-regulation of AChE-R and pro-inflammatory cytokines, which are involved in regulating the surgery-induced mood and memory disturbances.

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

OBJECTIVE

Approximately 30% of patients with depression fail to respond to a selective serotonin reuptake inhibitor (SSRI). Few studies have attempted to define these patients from a biological perspective. Studies suggest that overall patients with depression show increased production of proinflammatory cytokines. We examined pro- and anti-inflammatory cytokine levels in patients who were SSRI resistant.

METHODS

Plasma concentrations of IL-6, IL-8, IL-10, TNF-alpha and sIL-6R were measured with enzyme linked immunosorbent assays (ELISA) in DSM-1V major depressives who were SSRI resistant, in formerly SSRI resistant patients currently euthymic and in healthy controls.

RESULTS

Patients with SSRI-resistant depression had significantly higher production of the pro-inflammatory cytokines IL-6 (p=0.01) and TNF-alpha (p=0.004) compared to normal controls. Euthymic patients who were formerly SSRI resistant had proinflammatory cytokine levels which were similar to the healthy subject group. Anti-inflammatory cytokine levels did not differ across the 3 groups.

CONCLUSION

Suppression of proinflammatory cytokines does not occur in depressed patients who fail to respond to SSRIs and is necessary for clinical recovery.

Prophylactic IL-12 treatment reduces postoperative metastasis: mediation by increased numbers but not cytotoxicity of NK cells

Despite a promising potential, interleukin-12 immunotherapy has yielded limited clinical success while causing perilous toxicities. Here we study a context in which IL-12 may prove clinically beneficial--the removal of the primary tumor, when cell-mediated immunity (CMI) may eradicate minimal residual disease (MRD), but is inhibited by postoperative immunosuppression, potentially leading to enhanced malignant progression. F344 rats were preoperatively treated with IL-12 and inoculated postoperatively with syngeneic MADB106 tumor cells. An optimal regimen of eight-day sustained exposure to IL-12 was developed (1 microg/rat/day), which caused mild side effects, increased baseline resistance to experimental MADB106 metastasis, and abolished the promotion of metastasis by laparotomy and other immunosuppressive paradigms. Depletion of NK cells indicated their major role in controlling MADB106 metastasis in naïve and IL-12 treated rats. Studying NK cytotoxicity, we found that IL-12 did not potentiate activity per NK cell, nor protected it from suppression by surgery. However, IL-12 increased the numbers of NK cells in the circulation and marginating pulmonary pool of naïve and operated rats, and correspondingly increased total NK activity in these compartments. Therefore, this study indicates anti-tumor effects of IL-12 based on increased numbers of strategically located NK cells, and advocates a prophylactic approach against the potential metastasis-promoting effects of surgery.

Treating depression in the medically ill

Depression frequently is comorbid with a variety of medical illnesses; individuals who have such comorbidities may have increased morbidity and lower functional status. Usual antidepressant treatments can be effective in depressed patients who have comorbid medical illness. These patients, however, experience lower rates of recovery and remission of depressive symptoms and higher rates of relapse during follow-up than seen in patients who have MDD with no medical comorbidity. Comorbid medical illness therefore is a marker of treatment resistance in MDD. Collaborative treatments combining antidepressants, psychotherapy, education, and case management may be effective and could overcome the risk of treatment resistance. Two clinical strategies seem warranted in light of the studies presented here: (1) an increased index of suspicion for depression in medically ill patients, and (2) more intensive antidepressant treatment in depressed patients who have medical comorbidity.

Immune activation in patients with irritable bowel syndrome

BACKGROUND AND AIMS

We set out to test the hypothesis that irritable bowel syndrome (IBS) is characterized by an augmented cellular immune response with enhanced production of proinflammatory cytokines. We further aimed to explore whether symptoms and psychiatric comorbidity in IBS are linked to the release of proinflammatory cytokines.

METHODS

We characterized basal and Escherichia coli lipopolysaccharide (LPS)-induced cytokine production in peripheral blood mononuclear cells (PBMCs) from 55 IBS patients (18 mixed-, 17 constipation-, 20 diarrhea-predominant) and 36 healthy controls (HCs). PBMCs were isolated by density gradient centrifugation and cultured for 24 hours with or without (1 ng/mL) LPS. Cytokine production (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, and IL-6) was measured by enzyme-linked immunosorbent assay. Abdominal symptoms and psychiatric comorbidities were assessed by using the validated Bowel Disease Questionnaire and the Hospital Anxiety and Depression Scale.

RESULTS

IBS patients showed significantly (P < .017) higher baseline TNF-alpha, IL-1beta, IL-6, and LPS-induced IL-6 levels compared with HCs. Analyzing IBS subgroups, all cytokine levels were significantly (P < .05) higher in diarrhea-predominant IBS (D-IBS) patients, whereas constipation-predominant IBS patients showed increased LPS-induced IL-1beta levels compared with HCs. Baseline TNF-alpha and LPS-induced TNF-alpha and IL-6 levels were significantly higher in patients reporting more than 3 bowel movements per day, urgency, watery stools, and pain associated with diarrhea compared with patients without these symptoms (all P < .05). LPS-induced TNF-alpha production was associated significantly (r = 0.59, P < .001) with anxiety in patients with IBS.

CONCLUSIONS

Patients with D-IBS display enhanced proinflammatory cytokine release, and this may be associated with symptoms and anxiety.

Disturbance of serum interleukin-2 and interleukin-8 levels in posttraumatic and non-posttraumatic stress disorder earthquake survivors in northern China

OBJECTIVE

It is evident that immune cytokines are involved in the pathophysiology of posttraumatic stress disorder (PTSD), but results of different studies are still inconsistent. Here, serum interleukin (IL)-2, IL-6 and IL-8 levels were compared between earthquake survivors with PTSD, those with non-PTSD and normal controls to investigate whether there is any relationship between cytokine levels and PTSD. In addition, the relationship of these cytokines with psychological parameters of the disorder was examined as well.

METHODS

Thirty-four earthquake survivors with PTSD (according to DSM-IV criteria), 30 earthquake survivors with non-PTSD and 34 controls were recruited in northern China using the Composite International Diagnostic Interview instrument. Serum IL-2, IL-6 and IL-8 levels were compared. IL-2 levels were measured by radioimmunometric assay, while serum IL-6 and IL-8 levels were measured using sandwich enzyme-linked immunosorbent assay. Psychological symptoms were assessed using 3 subscales of the Symptoms Checklist (SCL-90-R), including depression, anxiety and somatization.

RESULTS

Only earthquake survivors diagnosed with PTSD had significantly lower serum IL-8 levels. Also, we found that earthquake survivors (either with PTSD or non-PTSD) had significantly lower serum IL-2 levels and more severe psychological symptoms. The severity of depressive and anxiety symptoms in earthquake survivors was positively related to serum IL-6 levels.

CONCLUSIONS

PTSD may be associated with a reduced level of serum IL-8, and traumatic survivors may be associated with a lower level of serum IL-2.

The evolutionary significance of depressive symptoms: different adverse situations lead to different depressive symptom patterns

Although much depression may be dysfunctional, the capacity to experience normal depressive symptoms in response to certain adverse situations appears to have been shaped by natural selection. If this is true, then different kinds of situations may evoke different patterns of depressive symptoms that are well suited to solving the adaptive challenges specific to each situation. The authors called this the situation-symptom congruence hypothesis. They tested this hypothesis by asking 445 participants to identify depressive symptoms that followed a recent adverse situation. Guilt, rumination, fatigue, and pessimism were prominent following failed efforts; crying, sadness, and desire for social support were prominent following social losses. These significant differences were replicated in an experiment in which 113 students were randomly assigned to visualize a major failure or the death of a loved one.

Trauma-induced systemic inflammatory response versus exercise-induced immunomodulatory effects

Accidental trauma and heavy endurance exercise, both induce a kind of systemic inflammatory response, also called systemic inflammatory response syndrome (SIRS). Exercise-related SIRS is conditioned by hyperthermia and concomitant heat shock responses, whereas trauma-induced SIRS manifests concomitantly with tissue necrosis and immune activation, secondarily followed by fever. Inflammatory cytokines are common denominators in both trauma and exercise, although there are marked quantitative differences. Different anti-inflammatory cytokines may be involved in the control of inflammation in trauma- and exercise-induced stress. Exercise leads to a balanced equilibrium between inflammatory and anti-inflammatory responses. Intermittent states of rest, as well as anti-oxidant capacity, are lacking or minor in trauma but are high in exercising individuals. Regular training may enhance immune competence, whereas trauma-induced SIRS often paves the way for infectious complications, such as sepsis.

Anesthesiologists at work: an increase in pro-inflammatory and Th2 cytokine production, and alterations in proliferative immune responses

BACKGROUND

Anesthesiologists are a population at high risk of alcohol and drug abuse, depression, suicide, and psychiatric hospitalization. The impact of their working milieu on specific immune indices has scarcely been studied, and it is assumed that immune perturbations may contribute to some of the above risks. This study took advantage of an unplanned, 3-month long strike of anesthesiologists, and explored its relations to specific immune measures.

METHODS

We assessed induced cytokine production and lymphocytes proliferative responses in blood samples taken from 10 anesthesiologists just before the strike and at its end, after a long period of markedly reduced workload.

RESULTS

The results indicated that the proliferative responses to phytohemagglutinin (PHA) and concanavalin A (Con A) were significantly lower at the end of the strike. At this time point, we observed a significant decrease in the production of interleukin-6 (IL-6), IL-10 and IL1ra levels, and a significant increase in IL-2 production. A strong trend towards a decline in tumor necrosis factor-alpha (TNF-alpha) levels was evident, while levels of IL-1beta were unchanged.

CONCLUSION

These findings suggest that the working conditions of anesthesiologists are associated with specific immune alterations, including a shift towards a Th2 cytokines' dominance, and an elevated pro-inflammatory cytokine response. A reduced Th1 profile has been related to increased susceptibility to infections, and high pro-inflammatory cytokine levels were recently proposed as etiological factors in cardiovascular diseases and in depression.

The proinflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha activate serotonin transporters

Proinflammatory cytokines and serotonergic homeostasis have both been implicated in the pathophysiology of major psychiatric disorders. We have demonstrated that activation of p38 mitogen-activated protein kinase (MAPK) induces a catalytic activation of the serotonin transporter (SERT) arising from a reduction in the SERT Km for 5-hydroxytryptamine (5-HT). As inflammatory cytokines can activate p38 MAPK, we hypothesized that they might also activate neuronal SERT. Indeed, Interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) stimulated serotonin uptake in both the rat embryonic raphe cell line, RN46A, and in mouse midbrain and striatal synaptosomes. In RN46A cells, IL-1beta stimulated 5-HT uptake in a dose- and time-dependent manner, peaking in 20 min at 100 ng/ml. This was abolished by IL-1ra (20 ng/ml), an antagonist of the IL-1 receptor, and by SB203580 (5 microM), a p38 MAPK inhibitor. TNF-alpha also dose- and time-dependently stimulated 5-HT uptake that was only partially blocked by SB203580. Western blots showed that IL-1beta and TNF-alpha activated p38 MAPK, in an SB203580-sensitive manner. IL-1beta induced an SB203580-sensitive decrease in 5-HT Km with no significant change in Vmax. In contrast, TNF-alpha stimulation decreased 5-HT Km and increased SERT Vmax. SB203580 selectively blocked the TNF-alpha-induced change in SERT Km. In mouse midbrain and striatal synaptosomes, maximal stimulatory effects on 5-HT uptake occurred at lower concentrations (IL-1beta, 10 ng/ml; TNF-alpha, 20 ng/ml), and over shorter incubation times (10 min). As with RN46A cells, the effects of IL-1beta and TNF-alpha were completely (IL-1beta) or partially (TNF-alpha) blocked by SB203580. These results provide the first evidence that proinflammatory cytokines can acutely regulate neuronal SERT activity via p38 MAPK-linked pathways.

Psychoneuroimmune Implications of Type 2 Diabetes

The idea that type 2 diabetes is associated with augmented innate immune function characterized by increased circulating levels of acute phase reactants and altered macrophage biology is fairly well established, even though the mechanisms involved in this complex interaction still are not entirely clear. To date, the majority of studies investigating innate immune function in type 2 diabetes are limited to the context of wound healing, atherosclerosis, stroke, and other commonly identified comorbidities. Several important recurring themes come out of these data. First, type 2 diabetes is associated with a state of chronic, subclinical inflammation. Second, in macrophages, type 2 diabetic conditions enhance proinflammatory reactions and impair anti-inflammatory responses. Third, after acute activation of the innate immune system in type 2 diabetes, recovery or resolution of inflammation is impaired. The consequences of type 2 diabetes-associated inflammatory alterations on PNI processes have been recognized only recently. Given the impact of diminished emotional well-being on the quality of life in patients who have type 2 diabetes, diabetes-induced exacerbation of PNI responses should be considered a serious complication of type 2 diabetes that warrants further clinical attention.

Age and Neuroinflammation: A Lifetime of Psychoneuroimmune Consequences

This article reviews the literature indicating that the innate immune cells of the brain become more reactive with age. Although it is unclear how glia reactivity increases, emerging evidence suggests these alterations allow exacerbated neuroinflammation and sickness behavior following peripheral immune activation. This amplified or prolonged exposure to inflammatory cytokines in the brain may impair neuronal plasticity and underlie a heightened neuroinflammatory response in the aged that also may lead to other neurobehavioral impairments such as delirium, depression, and, potentially, the onset of neurologic disease. Therefore pharmacologic strategies to decrease neuroinflammation associated with infection may be important for improving recovery from sickness and reducing neurobehavioral deficits in the elderly.

Reduction of apoptosis in the amygdala by an A2A adenosine receptor agonist following myocardial infarction

It has been observed that a cytokine synthesis inhibitor, pentoxifylline, prevents the apoptotic processes taking place in the amygdala following myocardial infarction. However, it is unknown if the cardioprotective effect of A(2A) adenosine receptor agonist, CGS21680, which reduces cytokine synthesis, would lead to such amygdala apoptosis regression. Thus, this study was designed to investigate whether cardioprotective A(2A) adenosine receptor activation reduces apoptosis in the amygdala following myocardial infarction. Anesthetized rats were subjected to left anterior descending coronary artery occlusion for 40 min, followed by 72 h of reperfusion. The A(2A) agonist CGS21680 (0.2 mug/kg/min i.v.) was administered continuously for 120 min, starting (1) five minutes prior to instituting reperfusion (Early) or (2) five minutes after the beginning of reperfusion (Late). After reperfusion, myocardial infarct size was determined and the amygdala was dissected from the brain. Infarct size was reduced significantly in the Early compared to the Control group (34.6 +/- 1.8% and 52.3 +/- 2.8% respectively; p < 0.05), with no difference compared to the Late group (40.1 +/- 6.1%). Apoptosis regression was documented in the amygdala of the Early group by an enhanced phosphatidylinositol 3-kinase-Akt pathway activation and Bcl-2 expression concurrently to a caspase-3 activation limitation and reduction in TUNEL-positive cells staining. On the other hand, amygdala TUNEL-positive cell numbers were not reduced in the Late group. Moreover, TNFalpha was significantly reduced in the amygdala of the Early group compared to the Control and Late groups. These results indicate that A(2A) adenosine receptor stimulation is associated with apoptosis regression in the amygdala following myocardial infarction.

Norman Cousins Lecture. The uses and abuses of psychoneuroimmunology: a global overview

Studies of interactions between the nervous and immune systems that effect immunological and behavioral changes are relevant to our understanding biological issues pertinent to evolution, ethology, ecology, and aging, in addition to our understanding the immune and nervous systems per se. Psychoneuroimmunology also relates to homeland security, science education, and the practice of conventional as well as complementary and alternative medicine. This paper will highlight just some of these global implications of psychoneuroimmunology.

The anxiogenic drug yohimbine activates central viscerosensory circuits in rats

Systemic administration of the alpha(2)-adrenoceptor antagonist yohimbine (YO) activates the HPA stress axis and promotes anxiety in humans and experimental animals. We propose that visceral malaise contributes to the stressful and anxiogenic effects of systemic YO and that YO recruits brainstem noradrenergic (NA) and peptidergic neurons that relay viscerosensory signals to the hypothalamus and limbic forebrain. To begin testing these hypotheses, the present study explored dose-related effects of YO on food intake, conditioned flavor avoidance (CFA), and Fos immunolabeling in rats. Systemic YO (5.0 mg/kg BW, i.p.) inhibited food intake, supported CFA, and increased Fos immunolabeling in identified NA neurons in the ventrolateral medulla, nucleus of the solitary tract, and locus coeruleus. YO also increased Fos in the majority of corticotropin releasing hormone-positive neurons in the paraventricular nucleus of the hypothalamus. YO administered at 1.0 mg/kg BW did not inhibit food intake, did not support CFA, and did not increase Fos immunolabeling. Retrograde neural tracing demonstrated that neurons activated by YO at 5.0 mg/kg BW included medullary and pontine neurons that project to the central nucleus of the amygdala and to the lateral bed nucleus of the stria terminalis, the latter region receiving comparatively greater input by Fos-positive neurons. We conclude that YO produces anorexigenic and aversive effects that correlate with activation of brainstem viscerosensory inputs to the limbic forebrain. These findings invite continued investigation of how central viscerosensory signaling pathways interact with hypothalamic and limbic regions to influence interrelated physiological and behavioral components of anxiety, stress, and visceral malaise.

Physical activity alters the brain Hsp72 and IL-1beta responses to peripheral E. coli challenge

Physically active rats have facilitated heat shock protein 72 (Hsp72) responses after stressor exposure in both brain and peripheral tissues compared with sedentary rats. This study verifies that physically active animals do not have elevated Hsp72 levels compared with sedentary animals in the hypothalamus, pituitary, or dorsal vagal complex. We then examined whether 1) physically active rats respond more efficiently than sedentary rats to a bacterial challenge; 2) peripheral immune challenge elicits brain induction of Hsp72; 3) this induction is facilitated by prior freewheel running; and 4) Hsp72 upregulation produced by peripheral immune challenge results in a commensurate decrease in the proinflammatory cytokine IL-1beta. Adult male Fischer 344 rats were housed with either a mobile or locked running wheel. Six weeks later, rats were injected intraperitoneally with saline or Escherichia coli and killed 30 min, 2.5 h, 6 h, and 24 h later. Serum endotoxin and IL-1beta, and peritoneal fluid endotoxin and E. coli colony-forming units (CFUs) were measured. Hsp72 and IL-1beta were measured in hypothalamus, pituitary, and dorsal vagal complex. The results were that physically active rats had a faster reduction in endotoxin and E. coli CFUs and lower levels of circulating endotoxin and cytokines compared with sedentary rats. E. coli challenge elicited significantly greater time-dependent increases of both Hsp72 and IL-1beta in hypothalamus, pituitary, and dorsal vagal complex of physically active animals but not sedentary animals. Contrary to our hypothesis, increases in Hsp72 were positively correlated with IL-1beta. This study extends our findings that physical activity facilitates stress-induced Hsp72 to include immunological stressors such as bacterial challenge and suggests that brain Hsp72 and IL-1beta responses to peripheral immune challenge may contribute to exercise-mediated resistance to long-term sickness.