Depressive symptoms and inflammation are independent risk factors of fatigue in breast cancer survivors.

BACKGROUND: Psychosocial and inflammatory factors have been associated with fatigue in breast cancer survivors. Nevertheless, the relative contribution and/or interaction of these factors with cancer-related fatigue have not been well documented. METHOD: This cross-sectional study enrolled 111 stage 0-III breast cancer patients treated with breast surgery followed by whole breast radiotherapy. Fatigue was measured by the total score of the Multidimensional Fatigue Inventory-20. Potential risk factors included inflammatory markers (plasma cytokines and their receptors and C-reactive protein; CRP), depressive symptoms (as assessed by the Inventory of Depressive Symptomatology-Self Reported), sleep (as assessed by the Pittsburgh Sleep Quality Index) and perceived stress (as assessed by the Perceived Stress Scale) as well as age, race, marital status, smoking history, menopause status, endocrine treatment, chemotherapy and cancer stage. Linear regression modeling was employed to examine risk factors of fatigue. Only risk factors with a significance level <0.10 were included in the initial regression model. A post-hoc mediation model using PROCESS SPSS was conducted to examine the association among depressive symptoms, sleep problems, stress, inflammation and fatigue. RESULTS: At 1 year post-radiotherapy, depressive symptoms (p<0.0001) and inflammatory markers (CRP: p = 0.015; interleukin-1 receptor antagonist: p = 0.014; soluble tumor necrosis factor receptor-2: p = 0.009 in separate models) were independent risk factors of fatigue. Mediation analysis showed that depressive symptoms also mediated the associations of fatigue with sleep and stress. CONCLUSIONS: Depressive symptoms and inflammation were independent risk factors for cancer-related fatigue at 1 year post-radiotherapy, and thus represent independent treatment targets for this debilitating symptom.

Conceptual convergence: increased inflammation is associated with increased basal ganglia glutamate in patients with major depression.

Inflammation and altered glutamate metabolism are two pathways implicated in the pathophysiology of depression. Interestingly, these pathways may be linked given that administration of inflammatory cytokines such as interferon-α to otherwise non-depressed controls increased glutamate in the basal ganglia and dorsal anterior cingulate cortex (dACC) as measured by magnetic resonance spectroscopy (MRS). Whether increased inflammation is associated with increased glutamate among patients with major depression is unknown. Accordingly, we conducted a cross-sectional study of 50 medication-free, depressed outpatients using single-voxel MRS, to measure absolute glutamate concentrations in basal ganglia and dACC. Multivoxel chemical shift imaging (CSI) was used to explore creatine-normalized measures of other metabolites in basal ganglia. Plasma and cerebrospinal fluid (CSF) inflammatory markers were assessed along with anhedonia and psychomotor speed. Increased log plasma C-reactive protein (CRP) was significantly associated with increased log left basal ganglia glutamate controlling for age, sex, race, body mass index, smoking status and depression severity. In turn, log left basal ganglia glutamate was associated with anhedonia and psychomotor slowing measured by the finger-tapping test, simple reaction time task and the Digit Symbol Substitution Task. Plasma CRP was not associated with dACC glutamate. Plasma and CSF CRP were also associated with CSI measures of basal ganglia glutamate and the glial marker myoinositol. These data indicate that increased inflammation in major depression may lead to increased glutamate in the basal ganglia in association with glial dysfunction and suggest that therapeutic strategies targeting glutamate may be preferentially effective in depressed patients with increased inflammation as measured by CRP.

Inflammation is associated with decreased functional connectivity within corticostriatal reward circuitry in depression.

Depression is associated with alterations in corticostriatal reward circuitry. One pathophysiological pathway that may drive these changes is inflammation. Biomarkers of inflammation (for example, cytokines and C-reactive protein (CRP)) are reliably elevated in depressed patients. Moreover, administration of inflammatory stimuli reduces neural activity and dopamine release in reward-related brain regions in association with reduced motivation and anhedonia. Accordingly, we examined whether increased inflammation in depression affects corticostriatal reward circuitry to lead to deficits in motivation and goal-directed motor behavior. Resting-state functional magnetic resonance imaging was conducted on 48 medically stable, unmedicated outpatients with major depression. Whole-brain, voxel-wise functional connectivity was examined as a function of CRP using seeds for subdivisions of the ventral and dorsal striatum associated with motivation and motor control. Increased CRP was associated with decreased connectivity between ventral striatum and ventromedial prefrontal cortex (vmPFC) (corrected P<0.05), which in turn correlated with increased anhedonia (R=-0.47, P=0.001). Increased CRP similarly predicted decreased dorsal striatal to vmPFC and presupplementary motor area connectivity, which correlated with decreased motor speed (R=0.31 to 0.45, P<0.05) and increased psychomotor slowing (R=-0.35, P=0.015). Of note, mediation analyses revealed that these effects of CRP on connectivity mediated significant relationships between CRP and anhedonia and motor slowing. Finally, connectivity between striatum and vmPFC was associated with increased plasma interleukin (IL)-6, IL-1beta and IL-1 receptor antagonist (R=-0.33 to -0.36, P<0.05). These findings suggest that decreased corticostriatal connectivity may serve as a target for anti-inflammatory or pro-dopaminergic treatment strategies to improve motivational and motor deficits in patients with increased inflammation, including depression.

The evolutionary significance of depression in Pathogen Host Defense (PATHOS-D).

Given the manifold ways that depression impairs Darwinian fitness, the persistence in the human genome of risk alleles for the disorder remains a much debated mystery. Evolutionary theories that view depressive symptoms as adaptive fail to provide parsimonious explanations for why even mild depressive symptoms impair fitness-relevant social functioning, whereas theories that suggest that depression is maladaptive fail to account for the high prevalence of depression risk alleles in human populations. These limitations warrant novel explanations for the origin and persistence of depression risk alleles. Accordingly, studies on risk alleles for depression were identified using PubMed and Ovid MEDLINE to examine data supporting the hypothesis that risk alleles for depression originated and have been retained in the human genome because these alleles promote pathogen host defense, which includes an integrated suite of immunological and behavioral responses to infection. Depression risk alleles identified by both candidate gene and genome-wide association study (GWAS) methodologies were found to be regularly associated with immune responses to infection that were likely to enhance survival in the ancestral environment. Moreover, data support the role of specific depressive symptoms in pathogen host defense including hyperthermia, reduced bodily iron stores, conservation/withdrawal behavior, hypervigilance and anorexia. By shifting the adaptive context of depression risk alleles from relations with conspecifics to relations with the microbial world, the Pathogen Host Defense (PATHOS-D) hypothesis provides a novel explanation for how depression can be nonadaptive in the social realm, whereas its risk alleles are nonetheless represented at prevalence rates that bespeak an adaptive function.

Molecular signatures of peripheral blood mononuclear cells during chronic interferon-α treatment: relationship with depression and fatigue.

BACKGROUND: Interferon-alpha (IFN-α) treatment for infectious disease and cancer causes high rates of depression and fatigue, and has been used to investigate the impact of inflammatory cytokines on brain and behavior. However, little is known about the transcriptional impact of chronic IFN-α on immune cells in vivo and its relationship to IFN-α-induced behavioral changes. METHOD: Genome-wide transcriptional profiling was performed on peripheral blood mononuclear cells (PBMCs) from 21 patients with chronic hepatitis C virus (HCV) either awaiting IFN-α therapy (n=10) or at 12 weeks of IFN-α treatment (n=11). RESULTS: Significance analysis of microarray data identified 252 up-regulated and 116 down-regulated gene transcripts. Of the up-regulated genes, 2'-5'-oligoadenylate synthetase 2 (OAS2), a gene linked to chronic fatigue syndrome (CFS), was the only gene that was differentially expressed in patients with IFN-α-induced depression/fatigue, and correlated with depression and fatigue scores at 12 weeks (r=0.80, p=0.003 and r=0.70, p=0.017 respectively). Promoter-based bioinformatic analyses linked IFN-α-related transcriptional alterations to transcription factors involved in myeloid differentiation, IFN-α signaling, activator protein-1 (AP1) and cAMP responsive element binding protein/activation transcription factor (CREB/ATF) pathways, which were derived primarily from monocytes and plasmacytoid dendritic cells. IFN-α-treated patients with high depression/fatigue scores demonstrated up-regulation of genes bearing promoter motifs for transcription factors involved in myeloid differentiation, IFN-α and AP1 signaling, and reduced prevalence of motifs for CREB/ATF, which has been implicated in major depression. CONCLUSIONS: Depression and fatigue during chronic IFN-α administration were associated with alterations in the expression (OAS2) and transcriptional control (CREB/ATF) of genes linked to behavioral disorders including CFS and major depression, further supporting an immune contribution to these diseases.

Association of a polymorphism in the indoleamine- 2,3-dioxygenase gene and interferon-α-induced depression in patients with chronic hepatitis C.

Interferon (IFN)-α treatment for infectious diseases and cancer is associated with significant depressive symptoms that can limit therapeutic efficacy. Multiple mechanisms have been implicated in IFN-α-induced depression including immune, neuroendocrine and neurotransmitter pathways. To further explore mechanisms of IFN-α-induced depression and establish associated genetic risk factors, single nucleotide polymorphisms in genes encoding proteins previously implicated in IFN-α-induced depression were explored in two self-reported ethnic groups, Caucasians (n=800) and African Americans (n=232), participating in a clinical trial on the impact of three pegylated IFN-α treatment regimens on sustained viral response in patients with chronic hepatitis C. Before treatment, all subjects were free of psychotropic medications and had a score ≤20 on the Center for Epidemiologic Studies Depression Scale (CES-D), which was used to assess depressive symptom severity throughout the study. In Caucasians, a polymorphism (rs9657182) in the promoter region of the gene encoding indoleamine-2,3-dioxygenase (IDO1) was found to be associated with moderate or severe IFN-α-induced depressive symptoms (CES-D>20) at 12 weeks of IFN-α treatment (P=0.0012, P<0.05 corrected). Similar results were obtained for treatment weeks 24, 36 and 48. In subjects homozygous for the risk allele (CC, n=150), the odds ratio for developing moderate or severe depressive symptoms at treatment week 12 was 2.91 (confidence interval: 1.48-5.73) compared with TT homozygotes (n=270). rs9657182 did not predict depression in African Americans, who exhibited a markedly lower frequency of the risk allele at this locus. The findings in Caucasians further support the notion that IDO has an important role in cytokine-induced behavioral changes.

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

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

Interferon-alpha effects on diurnal hypothalamic-pituitary-adrenal axis activity: relationship with proinflammatory cytokines and behavior.

Interferon (IFN)-alpha has been used to investigate pathways by which innate immune cytokines influence the brain and behavior. Accordingly, the impact of IFN-alpha on diurnal secretion of hypothalamic-pituitary-adrenal (HPA) axis hormones was assessed in 33 patients eligible for treatment with IFN-alpha plus ribavirin for hepatitis C. In addition, the relationship between IFN-alpha-induced HPA axis changes and proinflammatory cytokines and behavior was examined. Plasma ACTH and cortisol as well as tumor necrosis factor (TNF)-alpha, interleukin-6 and their soluble receptors, were measured hourly between 0900 and 2100 hours at baseline and following approximately 12 weeks of either no treatment (n=13) or treatment with IFN-alpha/ribavirin (n=20). Plasma IFN-alpha was also measured at each visit. Depression and fatigue were assessed using the Montgomery-Asberg depression rating scale and the multidimensional fatigue inventory. Compared to no treatment, IFN-alpha/ribavirin administration was associated with significant flattening of the diurnal ACTH and cortisol slope and increased evening plasma ACTH and cortisol concentrations. Flattening of the cortisol slope and increases in evening cortisol were correlated with increases in depression (r=0.38, P<0.05 and r=0.36, P<0.05, respectively) and fatigue (r=0.43, P<0.05 and r=0.49, P<0.01, respectively). No relationship was found between immune and HPA axis measures, although increases in plasma IFN-alpha, TNF-alpha and soluble TNF-alpha receptor2 were independently correlated with behavioral endpoints. These data indicate that chronic exposure to innate immune cytokines may contribute to the altered diurnal HPA axis activity and behavior found in medically ill individuals. However, given the lack of correlation between HPA axis and immune measures, the mechanism by which chronic cytokine exposure influences HPA axis function remains to be determined.

Lower CSF oxytocin concentrations in women with a history of childhood abuse.

Early-life disruption of the parent-child relationship, for example, in the form of abuse, neglect or loss, dramatically increases risk for psychiatric, as well as certain medical, disorders in adulthood. The neuropeptide oxytocin (OT) plays a seminal role in mediating social affiliation, attachment, social support, maternal behavior and trust, as well as protection against stress and anxiety. We therefore examined central nervous system OT activity after early-life adversity in adult women. We measured OT concentrations in cerebrospinal fluid (CSF) collected from 22 medically healthy women, aged 18-45 years, categorized into those with none-mild versus those with moderate-severe exposure to various forms of childhood abuse or neglect. Exposure to maltreatment was associated with decreased CSF OT concentrations. A particularly strong effect was identified for emotional abuse. There were inverse associations between CSF OT concentrations and the number of exposure categories, the severity and duration of the abuse and current anxiety ratings. If replicated, the association of lower adult CSF OT levels with childhood trauma might indicate that alterations in central OT function may be involved in the adverse outcomes of childhood adversity.

Functional polymorphisms in the interleukin-6 and serotonin transporter genes, and depression and fatigue induced by interferon-alpha and ribavirin treatment.

Depression and fatigue are frequent side effects of interferon-alpha (IFN-alpha) treatment, and there is compelling evidence that the inflammatory response system (including interleukin-6, IL-6) and the serotonergic system is important in the pathophysiology of such symptoms. Functional polymorphisms in the promoter region of the IL-6 gene (rs1800795) and serotonin transporter gene (5-HTTLPR) have been identified as regulating these systems. The present study aimed to determine if these polymorphisms were associated with the development of depression and fatigue during IFN-alpha and ribavirin treatment. Ninety-eight Caucasian patients receiving pegylated IFN-alpha and ribavirin treatment for chronic hepatitis C virus at King's College Hospital, London, and Emory University Hospital, Atlanta, participated in this prospective cohort study. Symptoms of depression and fatigue were measured before treatment and at weeks 4, 8, 12 and 24 during treatment. The 'low IL-6' synthesizing genotype (CC) was associated with significantly fewer symptoms of depression (effect size = 0.7 at week 24; F = 9.4, d.f. = 436, P = 0.002). The 'high transcription' serotonin transporter (5-HTT) genotype (LL) was also associated with significantly fewer symptoms of depression, but with a much smaller effect (effect size = 0.2 at week 24; F = 4.5, d.f. = 436, P = 0.03). Neither polymorphisms were associated with symptoms of fatigue (IL-6: F = 1.2, d.f. = 430, P = 0.2; 5-HTT: F = 0.5, d.f. = 430, P = 0.5). The smaller effects of the 5-HTT polymorphism on depression may be explained by an interaction between the genes (F = 5.0, d.f. = 434, P = 0.02): the 'protective' effect of the 5-HTTLPR polymorphism was evident only in the presence of the 'low IL-6' genotype (F = 5.4, d.f. = 64, P = 0.02), not in the presence of the 'high IL-6' genotype (F = 2.2, d.f. = 369, P = 0.1). The association between the IL-6 polymorphism and reduced risk of depressive symptoms confirms the role of the inflammatory response system in the pathophysiology of IFN-alpha-induced depression; in contrast, the effect of the 5-HTT gene was small and perhaps dependent on the status of the inflammatory response.

Paroxetine for prevention of depressive symptoms induced by interferon-alpha and ribavirin for hepatitis C.

BACKGROUND: Whether antidepressants prevent depression during interferon-alpha/ribavirin treatment for hepatitis C virus infection has yet to be established. AIM: To investigate the use of paroxetine in a prospective, double-blind, placebo-controlled study for this indication. METHODS: Sixty-one hepatitis C virus-infected patients were randomly assigned to the antidepressant, paroxetine (n = 28), or placebo (n = 33), begun 2 weeks before and continued for 24 weeks during interferon-alpha/ribavirin treatment. Primary endpoints included development of major depression and severity of depressive symptoms measured by the Montgomery Asberg Depression Rating Scale (MADRS). RESULTS: Rates of major depression during the study were low (17%) and did not differ between groups. Nevertheless, using published MADRS cut-off scores, the percent of subjects who met criteria for mild, moderate or severe depression during interferon-alpha/ribavirin therapy was significantly lower in paroxetine- vs. placebo-treated subjects (P = 0.02, Fisher's exact test). Assignment to paroxetine was also associated with significantly reduced depressive symptom severity. This effect was largely accounted for by participants with depression scores above the median (MADRS > 3) at baseline in whom paroxetine was associated with a maximal reduction in MADRS scores of 10.3 (95% CI: 2.1-18.5) compared with placebo at 20 weeks (P < 0.01). Study limitations included a small sample size and high drop-out rate. CONCLUSION: This double-blind, placebo-controlled trial provides preliminary data in support of antidepressant pre-treatment in hepatitis C virus patients with elevated depressive symptoms at baseline.

Endogenous glucocorticoids protect against TNF-alpha-induced increases in anxiety-like behavior in virally infected mice.

Endogenous glucocorticoids restrain proinflammatory cytokine responses to immune challenges such as viral infection. In addition, proinflammatory cytokines induce behavioral alterations including changes in locomotor/exploratory activity. Accordingly, we examined proinflammatory cytokines and open-field behavior in virally infected mice rendered glucocorticoid deficient by adrenalectomy (ADX). Mice were infected with murine cytomegalovirus (MCMV), and open-field behavior (36 h post-infection) and plasma concentrations of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 (42 h post-infection) were assessed. Compared to sham-ADX-MCMV-infected animals, ADX-MCMV-infected mice exhibited significant reductions in total distance moved, number of center entries, and time spent in center. These behavioral alterations were accompanied by significantly higher plasma concentrations of TNF-alpha and IL-6, both of which were correlated with degree of behavioral change. To examine the role of TNF-alpha in these behavioral alterations, open-field behavior was compared in wild-type (WT) and TNF-R1-knockout (KO), ADX-MCMV-infected mice. TNF-R1-KO mice exhibited significantly attenuated decreases in number of rearings, number of center entries and time spent in center, but not distance moved, which correlated with plasma IL-6. Given the potential role of brain cytokines in these findings, mRNA expression of TNF-alpha, IL-1 and IL-6 was assessed in various brain regions. Although MCMV induced increases in proinflammatory cytokine mRNA throughout the brain (especially in ADX animals), no remarkable differences were found between WT and TNF-R1-KO mice. These results demonstrate that endogenous glucocorticoids restrain proinflammatory cytokine responses to viral infection and their impact on locomotor/exploratory activity. Moreover, TNF-alpha appears to mediate cytokine-induced changes in open-field behaviors, especially those believed to reflect anxiety.

Interleukin 1alpha (IL-1alpha) induced activation of p38 mitogen-activated protein kinase inhibits glucocorticoid receptor function.

Previous studies have demonstrated that interleukinalpha (IL-1alpha) inhibits glucocorticoid receptor (GR) nuclear translocation and dexamethasone (Dex)-induced gene transcription. Given that IL-1alpha is a potent activator of the p38 mitogen-activated protein kinase (MAPK) signal transduction pathway and p38 MAPK has been associated with reduced GR function, we examined the role of p38 MAPK in IL-1alpha-mediated inhibition of GR function in mouse fibroblast cells stably transfected with a GR-mediated reporter gene construct (LMCAT cells). Treatment of LMCAT cells with IL-1alpha (1000 U/ml) for 24 h inhibited Dex (50 nM)-induced GRE-CAT activity by approximately 35%. When cells were cotreated for 24 h with IL-1alpha plus SB-203580 (0.5-1 microM), a selective p38 inhibitor, IL-1alpha's inhibitory effect on GR function as determined by Dex-induced GRE-CAT activity was reversed. Using gel mobility shift assay, SB-203580 was also found to reverse IL-1alpha inhibition of GR-GRE binding. Further confirming the role of p38 pathways, pretreatment of LMCAT cells with antisense oligonucleotides targeted to p38 MAPK completely abrogated IL-1alpha inhibition of Dex-induced GRE-CAT activity. Taken together, these results demonstrate that activation of p38 MAPK pathways are involved in IL-1alpha-mediated inhibition of GR function. In addition, these findings extend the intracellular targets of p38 to include the GR and indicate that p38 inhibitors may have special utility in immunologic and/or neuropsychiatric disorders associated with impaired GR-mediated feedback inhibition.

Association between decreased serum tryptophan concentrations and depressive symptoms in cancer patients undergoing cytokine therapy.

Cytokine therapy for cancer or viral diseases is accompanied by the development of depressive symptoms in a significant proportion of patients. Despite the increasing number of studies on the neurotoxic effects of cytokines, the mechanisms by which cytokines induce depressive symptoms remain largely unknown. In view of the relationship between neurotransmitter precursors and mood, the present study aimed at assessing the relationship between serum concentrations of the amino acids tryptophan and tyrosine, major precursors of serotonin and norepinephrine respectively, and depressive symptoms in cancer patients undergoing cytokine therapy. Sixteen cancer patients eligible to receive immunotherapy with interleukin-2 and/or interferon-alpha participated in the study. At baseline and after one week and one month of therapy, depressive symptoms were assessed using the Montgomery-Asberg Depression Rating Scale (MADRS), and blood samples were collected for the determination of the large neutral amino acids (LNAA) (tryptophan, tyrosine, valine, leucine, isoleucine, phenylalanine) which compete for transport across the blood-brain barrier. Serum concentrations of tryptophan as well as the tryptophan/LNAA ratio significantly decreased between baseline, one week and one month of therapy. The development and severity of depressive symptoms, especially anorexia, pessimistic thoughts, suicidal ideation and loss of concentration were positively correlated with the magnitude of the decreases in tryptophan concentrations during treatment. These findings indicate that the development of depressive symptoms in patients undergoing cytokine therapy could be mediated by a reduced availability of the serotonin relevant amino acid precursor, tryptophan.

Antidepressants enhance glucocorticoid receptor function in vitro by modulating the membrane steroid transporters.

1. Previous data demonstrate that the tricyclic antidepressant, desipramine, induces glucocorticoid receptor (GR) translocation from the cytoplasm to the nucleus in L929 cells and increases dexamethasone-induced GR-mediated gene transcription in L929 cells stably transfected with the mouse mammary tumour virus-chloramphenicol acetyltransferase (MMTV-CAT) reporter gene (LMCAT cells) (Pariante et al., 1997). 2. To extend these findings, the present study has investigated the effects of 24 h coincubation of LMCAT cells with dexamethasone and amitriptyline, clomipramine, paroxetine, citalopram or fluoxetine. 3. All antidepressants, except fluoxetine, enhanced GR-mediated gene transcription, with clomipramine having the greatest effect (10 fold increase). Twenty-four hours coincubation of cells with desipramine, clomipramine or paroxetine, also enhanced GR function in the presence of cortisol, but not of corticosterone. 4. It is proposed that these effects are due to the antidepressants inhibiting the L929 membrane steroid transporter, which actively extrudes dexamethasone and cortisol from the cell, but not corticosterone. This is further confirmed by the fact that clomipramine failed to enhance GR-mediated gene transcription in the presence of dexamethasone when the membrane steroid transporter was blocked by verapamil. 5. The membrane steroid transporters that regulate access of glucocorticoids to the brain in vivo, like the multiple drug resistance p-glycoprotein, could be a fundamental target for antidepressant action.

The neuroimmunology of stress and depression.

This article reviews evidence that shows a bidirectional relationship between the brain and the immune system. As a result of this relationship, mental factors such as stress and depression have been shown to affect immune system functioning, with both immunosuppression and immune activation being reported. Stress and depression also have been associated with worse outcomes in immune-related disorders including cancer and infectious diseases suggesting that stress/depression effects on the immune system are clinically relevant to disease expression. Conversely, several lines of evidence suggest that immune system activation such as during infectious diseases, cancer, and autoimmune disorders is associated with the development of behavioral symptoms similar to those seen in the context of chronic stress or major depression. These findings implicate a role for the immune system in the cause of behavioral disorders in a wide range of medical illnesses. Finally, a paradigm is proposed in which abnormal functioning of either the hypothalamic-pituitary-adrenal (HPA) axis or the inflammatory response system disrupts feedback regulation of both neuroendocrine and immune systems contributing to the development of neuropsychiatric and immunologic disorders.

Higher than normal plasma interleukin-6 concentrations in cancer patients with depression: preliminary findings.

OBJECTIVE: This study investigated whether cancer patients with and without major depression exhibit immune system abnormalities similar to those reported in medically healthy, depressed subjects without cancer. METHOD: The study subjects consisted of patients diagnosed with pancreatic, esophageal, or breast cancer. Other groups consisted of subjects with major depression (without cancer) and healthy comparison subjects. Subjects' diagnoses were made with the Structured Clinical Interview for DSM-III-R. Severity of depression was measured with the Hamilton Depression Rating Scale. Plasma concentrations of interleukin-6 (IL-6) and postdexamethasone cortisol were measured. RESULTS: Cancer patients with depression had markedly higher plasma concentrations of IL-6 than healthy comparison subjects and cancer patients without depression. Although significant correlations were found between Hamilton depression scale scores and plasma concentrations of postdexamethasone cortisol, no significant correlations were found between plasma IL-6 and postdexamethasone cortisol concentrations. CONCLUSIONS: Higher than normal plasma IL-6 concentrations were associated with a diagnosis of major depression in cancer patients. IL-6 may contribute to sickness behavior that has overlapping symptoms with major depression.