Unaltered monocyte function in patients with major depression before and after three months of antidepressive therapy

Peripheral blood cellular immunophenotype in depression: a systematic review and meta-analysis

INTRODUCTION

Meta-analyses implicate immune dysfunction in depression confirming increased levels of circulating immune proteins (e.g., cytokines) in depression cases compared to controls. White blood cells (WBC) both produce and are influenced by cytokines, and play key roles in orchestrating innate and adaptive immune responses, but their role in depression remains unclear. Therefore, a systematic review of studies of various WBC subsets in depression is required for a greater understanding of the nature of immune dysfunction in this illness.

METHODS

We searched PubMed and PsycINFO databases (inception to 5th April 2022) and conducted a systematic review and meta-analysis of identified studies comparing absolute count and/or relative percentage of flow cytometry-derived WBC subsets between depression cases and controls. Selected studies were quality assessed. Random-effect meta-analysis was performed.

RESULTS

Thirty-three studies were included and 27 studies (n = 2277) were meta-analysed. We report an increase in mean absolute counts of WBC (seven studies; standardised mean difference [SMD] = 1.07; 95% CI, 0.61-1.53; P < 0.01; I2 = 64%), granulocytes (two studies; SMD = 2.07; 95% CI, 1.45-2.68; P < 0.01; I2 = 0%), neutrophils (four studies; SMD = 0.91; 95% CI, 0.23-1.58; P < 0.01; I2 = 82%), monocytes (seven studies; SMD = 0.60; 95% CI, 0.19-1.01; P < 0.01; I2 = 66%), CD4+ helper T cells (11 studies; SMD = 0.30; 95% CI, 0.15-0.45; P < 0.01; I2 = 0%), natural killer cells (11 studies; SMD = 1.23; 95% CI, 0.38-2.08; P < 0.01; I2 = 95%), B cells (10 studies; SMD = 0.30; 95% CI, 0.03-0.57; P = 0.03; I2 = 56%), and activated T cells (eight studies; SMD = 0.45; 95% CI, 0.24-0.66; P < 0.01; I2 = 0%) in depression, compared to controls. Fewer studies reported relative percentage, indicating increased neutrophils and decreased total lymphocytes, Th1, and Th2 cells in depression.

CONCLUSIONS

Depression is characterised by widespread alterations in circulating myeloid and lymphoid cells, consistent with dysfunction in both innate and adaptive immunity. Immune cells could be useful biomarkers for illness subtyping and patient stratification in future immunotherapy trials of depression, along with cytokines, other biomarkers, and clinical measures.

Blood concentrations of neopterin and biopterin in subjects with depression: A systematic review and meta-analysis

INTRODUCTION

Pteridines, such as neopterin, biopterin, and tetrahydrobiopterin (BH₄), may be involved in depression pathophysiology owing to their links to immune-inflammatory response, oxidative and nitrosative stress, and monoaminergic transmission. Nonetheless, studies assessing pteridines in depression are inconsistent. We conducted a systematic review and meta-analysis of observational studies comparing blood pteridine concentrations between subjects with depression and healthy controls (HCs).

METHODS

We searched Embase, MEDLINE, and PsycInfo for articles indexed through November 2021. Study quality was appraised, evaluating age and gender comparability between groups, sample representativeness, and methods to assess depression. Random-effects meta-analyses were carried out, generating pooled standardized mean differences (SMDs). Heterogeneity across studies was estimated using the I² statistic.

RESULTS

Twenty-four studies, involving 3075 subjects, were included. Individuals with depression showed blood neopterin concentrations higher than HCs (k = 19; SMD = 0.36; p < 0.001) with moderate heterogeneity across studies (I² = 58.2%). No moderating role of age, gender, or type of blood sample was found. Sensitivity analyses showed no impact of inconsistency and quality of studies on findings. Neopterin concentrations were higher among individuals with major depressive disorder compared to HCs (SMD = 0.44; p < 0.001). This held true also when considering only drug-free subjects (SMD = 0.68; p = 0.003). No differences in biopterin concentrations were found between subjects with depression and HCs (k = 5; SMD = -0.35; p = 0.086), though this result was limited by inconsistency of findings (I² = 77.9%) and quality of studies. Finally, no sufficient data were available for a meta-analysis on BH₄.

CONCLUSIONS

As a whole, our work partly supports the hypothesis of an imbalance of pteridine metabolism in depression.

Effects of antidepressant drug therapy with or without physical exercise on inflammatory biomarkers in major depressive disorder: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To conduct a systematic review and meta-analysis of the effects of antidepressant drug therapy (with or without physical exercise) on peripheral inflammatory markers in patients with major depressive disorder (MDD).

METHODS

MEDLINE, PyscINFO, Embase, and Google Scholar databases were searched until May 2020. Randomized trials that measured at least one inflammatory biomarker and included adult outpatients with MDD under antidepressant drug therapy (any drug) with or without physical exercise (any modality) were eligible. Results were summarized using the standardized mean difference (SMD) with 95% confidence intervals (95% CI) under a random-effects model. The Cochrane risk of bias tool (2010) was used to evaluate the risk of bias in the included trials.

RESULTS

Sixty-three trials were identified, encompassing data from 3482 patients, and 20 investigated biomarkers. Trials had biases across multiple domains, rising concerns primarily to selection bias/performance bias/detection bias/attrition bias. SMDs between pre- and post-results indicated a significant reduction in the levels of IL-2 (SMD, - 0.25; 95% CI, - 0.41 to - 0.09, P = 0.002), IL-6 (SMD, - 0.19; 95% CI, - 0.35 to - 0.025, P = 0.024), IL-10 (SMD, - 0.32; 95% CI, - 0.57 to - 0.07, P = 0.011), and serum cortisol (SMD, - 0.35; 95% CI, - 0.58 to - 0.12, P = 0.002). Evidence supporting the influence of physical exercise combined with antidepressant drugs on peripheral inflammatory markers in MDD is sparse and heterogeneous.

CONCLUSION

There is some evidence that antidepressant drug therapy is associated with an overall positive reduction in inflammatory markers, but the evidence is heterogeneous. Further research linking how inflammatory biomarkers modulate physiology related to antidepressant response is required.

TRIAL REGISTRATION

CRD42020220735.

Glucocorticoid Resistance: Is It a Requisite for Increased Cytokine Production in Depression? A Systematic Review and Meta-Analysis

Background: Glucocorticoid resistance-reduced function of the glucocorticoid receptor (GR)-is seen in many depressed patients. It is argued that this resistance to glucocorticoids leads to failure of normal feedback regulation on the immune system. High levels of pro-inflammatory cytokines result. Purpose: We sought to identify evidence supporting or refuting a link between glucocorticoid resistance and immune dysregulation in depression and to summarize retrieved evidence in aggregate form. Methods: We systematically reviewed and meta-analyzed studies that examined cytokine levels in depressed patients compared with controls and that also reported a measure of glucocorticoid resistance. These measures included plasma cortisol, the dexamethasone suppression test (DST), GR expression levels, and the results of in vitro assays of GR function. We conducted four separate meta-analyses to test for moderating effects of glucocorticoid resistance on cytokine production in depression. Results: After sub-grouping 32 studies by the ratio of cortisol levels in patients compared with controls, we observed a trend for increasing glucocorticoid resistance (i.e., the most hypercortisolemic patients) to be associated with increased production of interleukin (IL)-6 [d = 0.94; 95% CI (0.29, 1.59)] and tumour necrosis factor (TNF)-α [d = 0.46; 95% CI (0.12, 0.79)]. We stratified nine studies that reported DST results by relative glucocorticoid resistance between patients and controls, identifying a trend for higher glucocorticoid resistance in patients, compared with controls, to be associated with higher cytokine production in patients (170 patients and 187 controls). This was particularly evident when studies were sub-grouped by source of cytokine-plasma (d = 1.04; 95% CI, 0.57-1.50) versus in vitro (d = 0.24; 95% CI, -0.20 to 0.67). Stratifying the four studies (147 patients and 118 controls) that used in vitro assays of GR function or GR expression to quantify glucocorticoid resistance revealed variable contributions to cytokine production in patients compared with controls (overall effect size: d = 1.35; 95% CI 0.53-2.18). Combining our analyses of studies that reported DST results with those that used in vitro assays of GR function or GR expression to quantify glucocorticoid resistance (302 patients and 277 controls), we noted that although depressed patients produced more cytokines than controls (d = 1.02; 95% CI, 0.55-1.49), there was no evident positive correlation between glucocorticoid resistance and inflammation. Conclusions: Our work provides some support for a model conceptualizing glucocorticoid resistance as a requisite for increased inflammation in depression. The limited number of studies identified highlights the need for purpose-designed investigations that directly examine the relationship between glucocorticoid resistance and cytokine production in depression.

The role of macrophages in anti-inflammatory activity of antidepressant drugs

Depression is a common disease influencing patients' quality of life, whose etiology involves complex interactions of environmental, genetic and immunological factors. The latter factors include proinflammatory activation of monocytes and macrophages and increased serum levels of proinflammatory cytokines, altogether formulated as the "macrophage theory of depression". Our current review summarizes the impact of the most commonly used antidepressant drugs on the immune response with special emphasis on the role of macrophages in the clinically observed effects. The anti-inflammatory action of antidepressants mainly results from their direct interaction with immune cells and from changes in the concentration and the relations of neurotransmitters sensed by these cells. The summarized data revealed that Mφs are one of the leading cell populations involved in drug-mediated immune effects that can be observed both in subjects with depression as well as in individuals not suffering from depression. Thus, currently reviewed immunomodulatory effects of the experimental use of different antidepressant drugs suggest the possibility of utilizing them in complex therapeutic strategies dedicated to various inflammatory and immune-mediated diseases. It is worth noting that an excessive inflammatory reaction is also associated with the pathogenesis of various cardiovascular, metabolic and neuro-endocrine diseases. Thus, the inclusion of antidepressants in the complex therapy of these disorders may have beneficial effects through the enhancement of the mood of the patient and alleviation of chronic inflammation. On the other hand, presented data suggest that the influence of chronically used antidepressants on anti-microbial and anti-tumor immunity could also be taken into consideration.

Inflammation and clinical response to treatment in depression: A meta-analysis

The depressive state has been characterised as one of elevated inflammation, which holds promise for better understanding treatment-resistance in affective disorders as well as for future developments in treatment stratification. Aiming to investigate alterations in the inflammatory profiles of individuals with depression as putative biomarkers for clinical response, we conducted meta-analyses examining data from 35 studies that investigated inflammation before and after treatment in depressed patients together with a measure of clinical response. There were sufficient data to analyse IL-6, TNFα and CRP. Levels of IL-6 decreased with antidepressant treatment regardless of outcome, whereas persistently elevated TNFα was associated with prospectively determined treatment resistance. Treatment non-responders tended to have higher baseline inflammation, using a composite measure of inflammatory markers. Our findings suggest that elevated levels of inflammation are contributory to treatment resistance. Combining inflammatory biomarkers might prove a useful tool to improve diagnosis and detection of treatment refractoriness, and targeting persistent inflammation in treatment-resistant depression may offer a potential target for the development of novel intervention strategies.

Neuroimmune and neuroendocrine abnormalities in depression: two sides of the same coin

Major depressive disorder has been linked to alterations in several interacting systems, particularly with respect to neuroendocrine and neuroinflammatory dysfunction. Increased levels of both cortisol and proinflammatory cytokines have regularly been described. This presents an apparent paradox, given the well-known anti-inflammatory properties of glucocorticoids, including inhibition of cytokine release. There are two competing theories to resolve this paradox: one proposes that reduced glucocorticoid signaling, as a result of glucocorticoid resistance, creates a permissive environment for an overactive innate immune system; the other theory focuses on evidence that glucocorticoids can be proinflammatory under some circumstances, depending on context and temporal factors. This review assesses the evidence base and limitations of both theories, discussing animal and clinical data, and preliminary work in human neural cells. Further work to delineate the relationship between neuroimmune and neuroendocrine systems in depression will be critical for understanding the biological perturbations underpinning depression, and therefore, for discerning treatment targets, and we include suggestions for future directions.

Depressive symptoms in hip fracture patients are associated with reduced monocyte superoxide production

Ageing is accompanied by reduced functioning of the immune system, termed immunesenescence which is associated with increased risk of infection and mortality. However the immune system does not operate in isolation and can be modified by many environmental factors, including stress. In this study we determined whether physical stress (hip fracture) and psychological distress (depressive symptoms) had additive effects upon the aged immune system, specifically on monocyte numbers and function. We assessed immune function in 101 hip fracture patients (81 female) 6weeks and 6months after injury and 43 healthy age matched controls (28 females). Thirty-eight of the hip fracture group were found to be depressed at the 6week sampling. No differences in peripheral monocyte count, distribution of monocyte subsets or TNFα secretion were observed between hip fracture patients and healthy controls. However we observed significantly reduced superoxide production in response to Escherichia coli in the monocytes of hip fracture patients who developed depressive symptoms compared with non-depressed hip fracture patients (p=0.002) or healthy controls (p=0.008) 6weeks after the fracture which remained decreased 6months following injury. In previous studies we have shown an effect of depression on neutrophil superoxide generation in hip fracture patients, suggesting a particular susceptibility of this aspect of immune cell function to psychological stress.

Exercise affects symptom severity but not biological measures in depression and somatization - results on IL-6, neopterin, tryptophan, kynurenine and 5-HIAA

Exercise leads to symptom reduction in affective disorders and functional somatic syndromes. Biological hypotheses of underlying mechanisms include serotonergic and immunological pathways. We aimed to investigate biological features in persons with major depression and somatoform syndromes, and to analyze effects of short-term graded exercise on these parameters. Baseline values for depressive and somatoform symptoms, tryptophan, kynurenine, 5-hydroxyindoleacetic acid, neopterin and interleukin-6 were compared with those after one week of increased and one week of reduced physical activity. Thirty-eight persons with major depression, 27 persons with a minimum of 6-8 somatoform symptoms, and 48 healthy controls participated in the study. Depressive and somatoform symptoms were reduced after the active week, and an interaction pointed towards group-specific reduction of psychopathology. Participants with major depression had lower levels of kynurenine compared to controls, with intermediate concentrations in somatoform patients. There were no systematic associations of symptom improvement with biological changes. A possible limitation of the design is that a control condition with low physical activity, but no placebo condition was included. People with multiple somatoform symptoms and major depression benefit from a short and low-graded exercise intervention. These effects do not seem to be mediated by changes in serotonergic and inflammatory parameters.

Tryptophan: the key to boosting brain serotonin synthesis in depressive illness

It has been proposed that focusing on brain serotonin synthesis can advance antidepressant drug development. Biochemical aspects of the serotonin deficiency in major depressive disorder (MDD) are discussed here in detail. The deficiency is caused by a decreased availability of the serotonin precursor tryptophan (Trp) to the brain. This decrease is caused by accelerated Trp degradation, most likely induced by enhancement of the hepatic enzyme tryptophan 2,3-dioxygenase (TDO) by glucocorticoids and/or catecholamines. Induction of the extrahepatic Trp-degrading enzyme indolylamine 2,3-dioxygenase (IDO) by the modest immune activation in MDD has not been demonstrated and, if it occurs, is unlikely to make a significant contribution. Liver TDO appears to be a target of many antidepressants, the mood stabilisers Li(+) and carbamazepine and possibly other adjuncts to antidepressant therapy. The poor, variable and modest antidepressant efficacy of Trp is due to accelerated hepatic Trp degradation, and efficacy can be restored or enhanced by combination with antidepressants or other existing or new TDO inhibitors. Enhancing Trp availability to the brain is thus the key to normalisation of serotonin synthesis and could form the basis for future antidepressant drug development.

Dexamethasone stimulated gene expression in peripheral blood is a sensitive marker for glucocorticoid receptor resistance in depressed patients

Although gene expression profiles in peripheral blood in major depression are not likely to identify genes directly involved in the pathomechanism of affective disorders, they may serve as biomarkers for this disorder. As previous studies using baseline gene expression profiles have provided mixed results, our approach was to use an in vivo dexamethasone challenge test and to compare glucocorticoid receptor (GR)-mediated changes in gene expression between depressed patients and healthy controls. Whole genome gene expression data (baseline and following GR-stimulation with 1.5 mg dexamethasone p.o.) from two independent cohorts were analyzed to identify gene expression pattern that would predict case and control status using a training (N=18 cases/18 controls) and a test cohort (N=11/13). Dexamethasone led to reproducible regulation of 2670 genes in controls and 1151 transcripts in cases. Several genes, including FKBP5 and DUSP1, previously associated with the pathophysiology of major depression, were found to be reliable markers of GR-activation. Using random forest analyses for classification, GR-stimulated gene expression outperformed baseline gene expression as a classifier for case and control status with a correct classification of 79.1 vs 41.6% in the test cohort. GR-stimulated gene expression performed best in dexamethasone non-suppressor patients (88.7% correctly classified with 100% sensitivity), but also correctly classified 77.3% of the suppressor patients (76.7% sensitivity), when using a refined set of 19 genes. Our study suggests that in vivo stimulated gene expression in peripheral blood cells could be a promising molecular marker of altered GR-functioning, an important component of the underlying pathology, in patients suffering from depressive episodes.

Elevated macrophage migration inhibitory factor and decreased transforming growth factor-beta levels in major depression--no influence of celecoxib treatment

OBJECTIVES

The involvement of an immune process in the pathophysiology of major depression disorder (MDD) was substantiated by studies demonstrating elevated levels of proinflammatory cytokines and prostaglandin E(2) (PGE(2)). Cyclooxygenase-2 (COX-2) inhibitors lead to a reduced production of PGE(2) and have been shown to improve depressive symptoms. We investigated the three immune parameters macrophage migration inhibitory factor (MIF), transforming growth factor-β (TGF-β) and soluble CD14 (sCD14) in a randomized, placebo-controlled trial of the COX-2 inhibitor celecoxib as add-on therapy in patients with MDD treated with reboxetine.

METHODS

Thirty-two patients with depression and 20 healthy controls participated in the study. The patients were treated with reboxetine and celecoxib or placebo. Immune parameters were measured from serum at baseline, after three and five weeks using ELISA.

RESULTS

Celecoxib as add-on strategy resulted in a significant reduction of Hamilton Depression Scale scores compared to placebo. Depressed patients showed significantly elevated MIF (p < 0.001) and reduced TGF-β (p = 0.006) concentrations at baseline. There was no difference in sCD14-concentrations. There was no difference between the placebo and the celecoxib group and no change over time.

LIMITATIONS

Limitations of the study are the relatively small sample size and lack of functional assessment of HPA axis in parallel.

CONCLUSIONS

MIF is a promising new candidate in the neuro-immune interplay that may link depressive symptoms, altered immune state and HPA-axis dysregulation. Reduced levels of TGF-β replicate previous findings and support the importance of this regulatory cytokine in major depressive disorder.

Antidepressant pharmacotherapy: focus on sex differences in neuroimmunopharmacological crossroads

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

A psychoneuroimmunological review on cytokines involved in antidepressant treatment response

OBJECTIVES

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

The association between serum levels of neopterin and number of depressive episodes of major depression

BACKGROUND

There is an interaction between the immune system and the central nervous system by means of hormones, peptides, and neurotransmitters. The aims of the present study were to determine whether the serum neopterin levels in patients with major depression (MD) differ from a healthy control group and to investigate the relationship between previous MD episodes and serum neopterin levels.

METHODS

Thirty patients who were admitted to the GATA Psychiatry Outpatient Clinics and were diagnosed with MD according to DSM-IV, and who agreed to participate in the study, were included in the study. Twenty-six healthy volunteers matched for age, gender, and level of education who agreed to participate in the study were served as controls. Peripheral venous blood samples were obtained from the patients and the control group for complete blood count, routine biochemistry, and the detection of serum neopterin levels. The analyses were performed in the laboratory of the GATA Department of Biochemistry.

RESULTS

There was no significant difference between the MD group and the healthy controls with respect to age, level of education, smoking, and gender. Serum neopterin levels of the MD group who had experienced two or more episodes were higher than the first-episode group and the control group. Age of onset and the number of previous episodes had an independent impact on serum neopterin levels in MD patients, while smoking did not show any effect.

CONCLUSION

In the present study, the neopterin levels of patients who had experienced two or more episodes were higher than the first-episode depressive group and healthy control group. It was also found that the number of previous depressive episodes and the ages of the MD cases had an independent effect on serum neopterin levels.

[Brain-immune interactions and implications in psychiatric disorders]

OBJECTIVE

This review will focus on the role of cytokines in the central nervous system and its implications to depressive disorder. We will then discuss the main findings of cytokine measurements in patients with major depressive disorder.

METHOD

We searched Pubmed for studies published from 1999-2007, using the keywords depression and cytokine; and depressive disorder and cytokine. We have focused on pro-inflammatory cytokine measurements in patients with depression syndrome using DSM-criteria.

RESULTS

Several lines of evidence suggest that cytokines have effects on depression, such as the induction of sickness behavior; clinical conditions related to cytokines that also overlap depressive symptoms; and immunotherapy that can lead to depressive symptoms attenuated by antidepressant treatment. Finally, patients with depression exhibit increased levels of pro-inflammatory cytokines, although conflicting results have been described.

CONCLUSION

Cytokines may play a role in the pathophysiology of some cases of depression, although a causal link has not been established yet. Further longitudinal studies are needed to determine patterns of cytokine in patients with major depressive disorder, taking into account confounding factors closely associated with the activation of pro-inflammatory cytokines. In addition, simultaneous measurements of multiple biomarkers could provide critical insights into mechanisms underlying major depressive disorder and a variety of common cytokine-related diseases.

Fluoxetine increases the nitric oxide production via nuclear factor kappa B-mediated pathway in BV2 murine microglial cells

A body of recent evidence implicates that antidepressants affect the inflammatory response and immune system. The present study is focused on the effects of the most widely used antidepressant agent, fluoxetine on the production of nitric oxide (NO) in BV2 microglial cells. In this study, we observed interesting result that NO production was increased by fluoxetine. The mRNA level of nitric oxide synthase (iNos, Nos2) by RT-PCR was also stimulated by fluoxetine. We next conducted electophoretic mobility shift assay (EMSA) to determine the DNA binding activity of nuclear factor kappa B (Nfkappab), an important upstream modulator for Nos2 expression, to find that fluoxetine increased DNA binding activity of Nfkappab. By Western blot analysis, phosphorylation levels of p38 mitogen-activated protein kinase (p38 Mapk, Mapk14) and extracellular signal-related kinase (Erk)1/2 Mapk, upstream signaling mediators of Nfkappab were found to be increased by fluoxetine. In addition, the mRNA expressions of other proinflammatory cytokines, interleukin 6 (Il6) and tumor necrosis factor alpha (Tnfalpha) were examined. The expressions of both Il6 and Tnfalpha by fluoxetine treatment were similar to those of Nos2 and Nfkappab. Taken together, our results show that fluoxetine stimulates NO production via Nfkappab-mediated pathway in BV2 cells.

Major depression and immunity in alcohol-dependent persons

Altered immunity has been associated with both alcoholism and major depression (MD). We investigated the contribution of MD, as well as alcoholism, to in vitro measures of immunity in inner-city alcohol-dependent (SCID-DSM-III-R) persons and community nonabusers, all otherwise in good health.

METHODS

Alcohol-dependent persons at an ambulatory alcohol treatment center who did not abuse other substances were studied along with the comparison sample (total n=122). Enumerative and functional immune measures included leukocyte and lymphocyte subsets, mitogen response, natural killer cell activity (NKCA), and granulocytic phagocytosis.

RESULTS

Controlling for alcohol dependence, age, gender, racial background, and medical status, MD was associated with decreased phytohemagglutinin (PHA) responses (p<.03), possibly decreased NKCA (p<.08), and increased circulating monocytes (p<.04). Controlling for MD, age, gender, racial background, and medical status, alcohol dependence was associated with decreased circulating B lymphocytes (p<.02), possibly decreased CD56+ (NK) cells (p<.06), and increased monocytes (p<.04). Responses to concanavalin A and pokeweed mitogen, granulocyte functions, and the composition of other leukocyte and lymphocyte subsets showed no evidence of being associated with MD or with alcoholism (p>.1). Secondary analyses exploring factors such as recent alcohol use, cigarette use, and nutrition suggested that these factors accounted for the altered lymphocyte subsets associated with alcoholism and the possibly decreased NKCA with MD. They did not account for the association of MD with increased monocytes and decreased PHA.

DISCUSSION

MD-associated immune changes in alcoholics are modest and consistent with those seen in MD without alcoholism. Some MD- and many alcoholism-associated immune effects appear related to factors such as cigarette use and recent alcohol exposure.

Glucocorticosteroid therapy decreases CD14-expression and CD14-mediated LPS-binding and activation of monocytes in patients suffering from systemic lupus erythematosus

In order to study the possible action of glucocorticosteroids (GCS) on the CD14/Toll like receptor mediated activation of monocytes the CD14-expression, CD14-mediated LPS binding and activation of these cells of patients suffering from Systemic Lupus Erythematosus receiving no, low dose or pulse steroid treatment was studied. The CD14-expression was determined on whole blood monocytes by flow cytometry, while the LPS-binding of an FITC-LPS preparate and the LPS-induced TNFalpha secretion were tested on isolated monocytes. The CD14-dependent and -independent LPS-binding and activation were evaluated with the help of a blocking anti-CD14 mAb. Our results showed that the CD14-expression, CD14-dependent LPS-binding and activation were significantly inhibited by the in vivo applied pulse steroid therapy. In contrast, the CD14-independent LPS-binding and activation were not altered by the GCS treatment. Our data provide further in vivo evidence for a possible new way of GCS therapy is able to initiate its anti-inflammatory action.

Cytokines as mediators of depression: what can we learn from animal studies?

It has recently been postulated that cytokines may cause depressive illness in man. This hypothesis is based on the following observations: 1. Treatment of patients with cytokines can produce symptoms of depression; 2. Activation of the immune system is observed in many depressed patients; 3. Depression occurs more frequently in those with medical disorders associated with immune dysfunction; 4. Activation of the immune system, and administration of endotoxin (LPS) or interleukin-1 (IL-1) to animals induces sickness behavior, which resembles depression, and chronic treatment with antidepressants has been shown to inhibit sickness behavior induced by LPS; 5. Several cytokines can activate the hypothalamo-pituitary-adrenocortical axis (HPAA), which is commonly activated in depressed patients; 6. Some cytokines activates cerebral noradrenergic systems, also commonly observed in depressed patients; 7. Some cytokines activate brain serotonergic systems, which have been implicated in major depressive illness and its treatment. The evidence for each of these tenets is reviewed and evaluated along with the effects of cytokines in classical animal tests of depression. Although certain sickness behaviors resemble the symptoms of depression, they are not identical and each has distinct features. Thus the value of sickness behavior as an animal model of major depressive disorder is limited, so that care should be taken in extrapolating results from the model to the human disorder. Nevertheless, the model may provide insight into the etiology and the mechanisms underlying some symptoms of major depressive disorder. It is concluded that immune activation and cytokines may be involved in depressive symptoms in some patients. However, cytokines do not appear to be essential mediators of depressive illness.

Immune parameters in patients with anxiety or depression during psychotherapy

BACKGROUND

Numerous studies have described distinctive immunological findings in patients with depression. In contrast, only very little is known about the possible influence of anxiety disorders on the immune system. It is also unknown whether treatment with psychotherapy alone has any influence on immunological variations in patients with psychiatric disorders.

METHODS

We measured immunological and psychological parameters in patients with minor depression (N=10) or anxiety disorder (N=13) over an 8-week course of inpatient psychotherapy. Data for patients and a group of healthy controls (N=11) were recorded three times in 4-week intervals. A FACS analysis revealed the composition of lymphocyte subpopulations. The production of reactive oxygen species (ROS) by phagocytes was analyzed using lucigenin-enhanced chemiluminescence.

RESULTS

On admission, patients with anxiety disorder showed a markedly elevated ratio of CD4(+) (T helper) versus CD8(+) (T suppressor/cytotoxic) lymphocytes compared to healthy controls (P<0.001) and minor depressives (P<0.01). The increased ratio in patients with anxiety disorder could mainly be attributed to a reduced count in CD8(+) T cells compared to healthy controls (P<0.01) and depressives (P<0.05). There were no differences between patients with depression and healthy controls with respect to the CD4(+)/CD8(+) ratio. We did not observe any differences in the production of ROS by phagocytes in patients compared to healthy controls. The CD4(+)/CD8(+) ratio remained elevated in patients with anxiety disorders during the following 8 weeks. There were no significant changes in this parameter over the course of the inpatient treatment.

LIMITATIONS

As a pilot study on the immune status in patients with anxiety disorders, the study's main limitation is the relatively low number of patients observed.

CONCLUSIONS

In this study we demonstrated for the first time marked immunological changes in patients with anxiety disorders. In addition, our results provide preliminary evidence that these immunological variations are not reversible by an 8-week course of inpatient psychotherapy alone.

Monocytic parameters in patients with dysthymia versus major depression

BACKGROUND

The studies on monocytic function during depression are controversial. A better knowledge of affective disorders may improve the differential diagnosis of depression subtypes. Our goals are to examine if there are differences in monocytic function in patients with major depression and dysthymia.

METHOD

Twenty-two depressed patients (12 dysthymia and 10 major depression) and 15 healthy controls participated in the study. We analyzed monocyte count, monocyte subsets (CD14+, CD16+, and HLA class-II+), respiratory burst activity, phagocytic index and the interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNFalpha) production.

RESULTS

Depressed patients showed elevated IL-1beta (P<0.05) and IL-6 (P<0.01), elevated monocytic respiratory burst activity (P<0.01); and reduced surface molecule expression HLA class-II and phagocytosis (P<0.01) compared with controls. We found no differences in any monocytic parameters between dysthymia and major depression.

LIMITATIONS

The small sample size and the short wash-out reduce the reliability of the results.

CONCLUSIONS

Major depression and dysthymia show similar signs of both monocytic activation and suppression. These alterations may be due to the depressive syndrome and not to the characteristics of depression subtypes studied.

Cytokines in depression and heart failure

OBJECTIVE

There is a convincing body of evidence linking depression, cardiovascular disease, and mortality. There is also growing evidence that depression is a risk factor for congestive heart failure (CHF) and that CHF patients with major depression have higher rates of mortality and repeat hospitalizations. Currently there are no proposed neurobiological or neuroimmune mechanisms for the comorbidity of heart failure and depression.

METHODS

This review focuses on the recent literature about the role of cytokines in CHF and depression as separate conditions. This review also attempts to identify the overlapping immunological mechanisms that have a potential for future research in the pathophysiology of comorbid depression and CHF.

RESULTS

Results of current studies suggest that cytokines exert deleterious effects on the heart and that soluble tumor necrosis factor (TNF) receptor 2 leads to reversal of the cardiotoxic effects of TNF, although the clinical significance of this is unclear. Major depression has been associated with alteration of various aspects of the innate immune system, including cellular components (such as microphages, neutrophils, and natural killer cells) and soluble mediators (such as acute-phase reaction proteins and cytokines). It is inconclusive whether antidepressants have immunoregulatory effects.

CONCLUSIONS

The literature has not yet addressed the role of cytokines in comorbid depression and CHF. But cytokines may provide a new avenue in understanding brain-body interaction in depression and heart failure.

Effects of tryptophan depletion and catecholamine depletion on immune parameters in patients with seasonal affective disorder in remission with light therapy

BACKGROUND

Altered immunologic parameters are found in symptomatic depressed patients relative to remitted depressed patients and healthy controls. We investigated whether tryptophan depletion and catecholamine depletion induce alterations in immunologic parameters in patients with seasonal affective disorder remitted on light therapy, and whether these changes are associated with changes in mood.

METHODS

Remitted patients with seasonal affective disorder underwent tryptophan depletion, catecholamine depletion, and sham depletion in a prospective randomized, double-blind crossover design. Measures of depression, plasma levels of tryptophan and catecholamine metabolites, and plasma levels of cytokines (sIL-4, IL-6, neopterin, sTNF-R1 and sTNF-R2) were obtained at baseline, and 7, 24, and 30 hours after monoamine depletion.

RESULTS

Tryptophan depletion decreased plasma total and free tryptophan levels; catecholamine depletion decreased plasma 3-methoxy-4-hydroxyphenylethyleneglycol and homovanillic acid levels. Tryptophan depletion and catecholamine depletion, but not sham depletion, induced a transient exacerbation of depressive symptoms (p <.001); plasma neopterin levels increased during tryptophan depletion and catecholamine depletion (p <.05). Tryptophan depletion and catecholamine depletion induced a transient reduction of plasma sIL-4 levels (p <.05). A significant correlation was found between sIL-4R levels and depression ratings after tryptophan depletion (r = -.61, p <.05).

CONCLUSIONS

The monoamine depletion-induced alterations of humoral and cellular immunity suggest a potential role of immunologic parameters in the pathophysiology of seasonal affective disorder; however, the results must be considered preliminary and require further study.

Antidepressant treatment of cytokine-induced mood disorders

Significant evidence suggests that the immune system is capable of profoundly affecting central nervous system (CNS) functioning in ways that may contribute to the development and expression of neuropsychiatric disorders, including disorders of mood. This paper reviews evidence that the production of proinflammatory cytokines, whether in the context of therapeutic administration (e.g. interferon-α-2b for hepatitis C infection) or medical illness, induces a state of sickness behavior that closely resembles major depression. Antidepressants have been shown to abolish or attenuate cytokine-induced sickness behavior in laboratory animals and to protect against the development of major depression in the context of therapeutic cytokine administration in humans. Potential mechanisms by which antidepressants ameliorate depressive and/or sickness symptoms in the context of immune activation include direct effects on immune cell functioning, as well as modulatory effects on monoamine neurotransmitters, intracellular second messenger pathways and the neuroendocrine system, in particular the hypothalamic-pituitary-adrenal axis.

The relationship of depression and stressors to immunological assays: a meta-analytic review

This is a broad meta-analysis of the relations of both depression and stressors to immunological assays. The number of study samples (greater than 180) and measures (greater than 40) is much more extensive than any so far. Analyses are done by both fixed and random effects. By a fixed-effects analysis, both major depression and naturally occurring acute stressors are associated with (1) an overall leukocytosis, (2) mild reductions in absolute NK-cell counts and relative T-cell proportions, (3) marginal increases in CD4/CD8 ratios, and (4) moderate decreases in T- and NK-cell function. However, the degree of heterogeneity of the studies' results raises questions about their robustness. Therefore, we also did the first random effects analysis to estimate what is likely to appear in future studies. For depression, the analysis showed the immunological correlates included (1) an overall leukocytosis, manifesting as a relative neutrophilia and lymphoenia; (2) increased CD4/CD8 ratios; (3) increased circulating haptoglobin, PGE(2), and IL-6 levels; (4) reduced NK-cell cytotoxicity; and (5) reduced lymphocyte proliferative response to mitogen. For stressors, the random effects analysis showed that future studies are likely to find the following effects: (1) an overall leukocytosis, manifesting as an absolute lymphocytosis; (2) alterations in cytotoxic lymphocyte levels, CD4/CD8 ratios, and natural killer cell cytotoxicity with the direction of change depending on the chronicity of the stressor; (3) a relative reduction of T-cell levels; (3) increased EBV antibody titers; (4) reduced lymphocyte proliferative response and proportion of IL-2r bearing cells following mitogenic stimulation; and (5) increased leukocyte adhesiveness. The random-effects analysis revealed that for both major depression and naturally occurring stressors the following effects are shared: leukocytosis, increased CD4/CD8 ratios, reduced proliferative response to mitogen, and reduced NK cell cytotoxicity. The implications for these findings for disease susceptibility and the pathophysiology of these conditions is discussed.

Plasma levels of cytokines and soluble cytokine receptors in psychiatric patients upon hospital admission: effects of confounding factors and diagnosis

It has been hypothesized that the immune system plays a pathogenetic role in psychiatric disorders, in particular in major depression and schizophrenia. This hypothesis is supported by a number of reports on altered circulating levels and in vitro production of cytokines in these disorders. However, the respective evidence is not consistent. This may be in part due to an incomplete control for numerous confounding influences in earlier studies. We investigated the plasma levels of cytokines and soluble cytokine receptors in psychiatric patients (N = 361) upon hospital admission and compared the results to those obtained in healthy controls (N = 64). By multiple regression analysis we found that circulating levels of interleukin-1 receptor antagonist (IL-1Ra), soluble IL-2 receptor (sIL-2R), tumor necrosis factor-alpha (TNF-alpha), soluble TNF receptors (sTNF-R p55, sTNF-R p75) and IL-6 were significantly affected by age, the body mass index (BMI), gender, smoking habits, ongoing or recent infectious diseases, or prior medication. Cytokine or cytokine receptor levels were significantly increased in patients treated with clozapine (sIL-2R, sTNF-R p75), lithium (TNF-alpha, sTNF-R p75, IL-6) or benzodiazepines (TNF-alpha, sTNF-R p75). Taking all these confounding factors into account, we found no evidence for disease-related alterations in the levels of IL-1Ra, sIL-2R, sTNF-R p75 and IL-6, whereas levels of TNF-alpha and sTNF-R p55 in major depression and sTNF-R p55 in schizophrenia were slightly decreased compared to healthy controls. We conclude that, if confounding factors are carefully taken into account, plasma levels of the above mentioned cytokines and cytokine receptors yield little, if any, evidence for immunopathology in schizophrenia or major depression.

Plasma neopterin in major depression: relationship to basal and stimulated pituitary-adrenal cortical axis function

We measured plasma neopterin at baseline and after oCRH and ACTH(1-24) stimulation tests in 35 unmedicated, adult major-depressive patients (mean age = 41 +/- 12 years) and in 35 normal control subjects individually matched to the patients. Neopterin is released by gamma-interferon-stimulated macrophages; because gamma-interferon is secreted by activated T-lymphocytes, elevated circulating neopterin is considered to reflect activation of the cell-mediated immune system. Plasma ACTH(1-39) and cortisol also were measured as indicators of pituitary-adrenal axis activity. Baseline plasma neopterin did not differ significantly between patients and controls (medians = 6.25 and 6.57 microg/l, respectively), but the baseline neopterin:creatinine ratio showed a trend toward lower values in the patients (P < 0.07). There was no apparent plasma neopterin change from baseline (area under the curve-AUC) following oCRH or ACTH(1-24) administration in either group of subjects. As with baseline neopterin, there was no significant patient-control difference in neopterin AUC following either hormone challenge, but there were trends toward lower neopterin:creatinine ratios in the patients following both challenges. In the patients, neither baseline neopterin nor neopterin AUCs following hormone challenge were significantly correlated with age, duration of depressive episode, lifetime number of episodes, melancholic subtype, Hamilton Depression Scale total score, Hamilton factor scores, or the Hamilton suicidality item score.