Increased serum IL-6 and IL-1 receptor antagonist concentrations in major depression and treatment resistant depression

Depressive symptoms, omega-6:omega-3 fatty acids, and inflammation in older adults

OBJECTIVE

To address how interactions between polyunsaturated fatty acid (PUFA) levels and depressive symptoms were related to proinflammatory cytokine synthesis. Depression and stress promote proinflammatory cytokine production. Dietary intakes of omega-3 (n-3) and omega-6 (n-6) PUFAs also influence inflammation; high n-6:n-3 ratios enhance proinflammatory cytokine production, although n-3 has anti-inflammatory properties.

METHODS

Blood samples from 43 older adults (mean age = 66.67 years, SD = 10.09) provided data on PUFAs and tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-6 soluble receptor (sIL-6r). Depressive symptoms were assessed by the Center for Epidemiological Studies Depression Scale.

RESULTS

Depressive symptoms and n-6:n-3 ratios worked together to enhance proinflammatory cytokines beyond the contribution provided by either variable alone, with substantial variance explained by their interaction: 13% for IL-6 and 31% for TNF-alpha, whereas full models accounted for 18% and 40%, respectively. Although predicted cytokine levels were consistent across n-6:n-3 ratios with low depressive symptoms, higher n-6:n-3 ratios were associated with progressively elevated TNF-alpha and IL-6 levels as depressive symptoms increased. Higher levels of sIL-6r were associated with higher n-6:n-3 ratios. Six individuals who met the criteria for major depressive disorder had higher n-6:n-3 ratios and TNF-alpha, IL-6, and sIL-6r levels than those who did not meet the criteria; excluding these six individuals reduced the variance explained by the depressive symptoms and n-6:n-3 ratio interaction.

CONCLUSIONS

Diets with high n-6:n-3 PUFA ratios may enhance the risk for both depression and inflammatory diseases.

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.

Heart rate variability and markers of inflammation and coagulation in depressed patients with coronary heart disease

BACKGROUND

Depression is associated with an increased risk for cardiac morbidity and mortality in patients with coronary heart disease (CHD). Cardiac autonomic nervous system (ANS) dysregulation, proinflammatory processes, and procoagulant processes have been suggested as possible explanations.

METHODS

Heart rate variability (HRV), an indicator of cardiac autonomic regulation, and markers of inflammation [C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha)] and coagulation (fibrinogen) were assessed in 44 depressed patients with CHD.

RESULTS

Moderate, negative correlations were found between fibrinogen and four measures of HRV. IL-6 also negatively correlated with one measure of HRV (total power) and was marginally related to two others (very low frequency and low frequency power). Neither CRP nor TNF-alpha was significantly related to any measure of HRV.

CONCLUSIONS

The finding that fibrinogen and IL-6 are moderately related to HRV suggests a link between these factors in depressed CHD patients. The relationship between ANS function and inflammatory and coagulant processes should be investigated in larger mechanistic studies of depression and cardiac morbidity and mortality.

Differential effects of faith-based coping on physical and mental fatigue in middle-aged and older cardiac patients

PURPOSE

This analysis investigated the effect of faith-based coping used by cardiac patients undergoing surgery on physical and mental fatigue, symptoms which have significant prognostic implications for mortality. Particularly, we explored whether this faith effect is independent or explained by positive mediators.

METHODS

Two weeks preoperatively, 481 patients (male, 58%; mean age = 62 years) were recruited for three sequential interviews. Among them, 426 completed the second interview, and 335 completed the post-operative follow-up. Cross-clamp and bypass time were obtained from patients' charts. Plasma interlukin-6 (IL-6) was used as a correlate of age-associated diseases and frailty.

RESULTS

Hierarchical multiple regression analyses showed that pre-operative positive religious coping styles and optimism contributed to reduced physical fatigue, controlling for post-operatively confirmed prayer coping and such covariates as severe injury. Depression and lower-back problems contributed to mental fatigue. No potential mediators explained these effects.

CONCLUSION

Faith-based coping and optimism are independent predictors of physical fatigue.

Cytokine, sickness behavior, and depression

Sufficient evidence is now available to accept the concept that the brain recognizes cytokines as molecular signals of sickness. Clarifying the way the brain processes information generated by the innate immune system is accompanied by a progressive elucidation of the cellular and molecular components of the intricate system that mediates cytokine-induced sickness behavior. We are still far, however, from understanding the whole. Among the hundreds of genes that proinflammatory cytokines can induce in their cellular targets, only a handful has been examined functionally. In addition, a dynamic view of the cellular interactions that occur at the brain sites of cytokine production and action is missing, together with a clarification of the mechanisms that favor the transition toward pathology.

Inflammation and depression: is there a causal connection with dementia?

Epidemiological studies show that there is a correlation between chronic depression and the likelihood of dementia in later life. There is evidence that inflammatory changes in the brain are pathological features of both depression and dementia. This suggests that an increase in inflammation-induced apoptosis, together with a reduction in the synthesis of neurotrophic factors caused by a rise in brain glucocorticoids, may play a role in the pathology of these disorders. A reduction in the neuroprotective components of the kynurenine pathway, such as kynurenic acid, and an increase in the neurodegenerative components, 3- hydroxykynurenine and quinolinic acid, contribute to the pathological changes. Such changes are postulated to cause neuronal damage and thereby predispose chronically depressed patients to dementia.

Impact of gender and menstrual cycle phase on plasma cytokine concentrations

OBJECTIVE

The lifetime prevalence of major depression is twice as high in females as in males. Depression is known to increase at periods where there are changes in gonadal hormones. We examined pro- and anti-inflammatory cytokine levels during the normal menstrual cycle of healthy females compared to similar time points in healthy males.

METHODS

Plasma concentrations of interleukin (IL)-4, IL-6, IL-8, IL-10, tumour necrosis factor-alpha (TNF-alpha) and soluble IL-6 receptor (sIL-6R) were measured with enzyme-linked immunosorbent assays in healthy females during the normal ovulatory menstrual cycle and also in males at similar time points.

RESULTS

The luteal phase of the menstrual cycle is associated with increased production of sIL-6R, IL-4 and TNF-alpha compared to the early follicular phase. No change was observed in IL-6, IL-8 and IL-10 concentration throughout the menstrual cycle. We found IL-4 positively correlated with oestrogen while TNF-alpha positively correlated with progesterone. Females were found to have significantly higher concentrations of TNF-alpha and sIL-6R across all phases of the menstrual cycle, compared to males across similar time points.

CONCLUSION

The normal menstrual cycle is associated with increased production of sIL-6R, IL-4 and TNF-alpha in the luteal phase compared to the early follicular phase. Females have significantly higher concentrations of sIL-6R and TNF-alpha at all time points across the menstrual cycle than males.

Biomarkers of depression in cancer patients

BACKGROUND

Inflammation and perturbation of the hypothalamic-pituitary-adrenal (HPA) axis function appears to play a putative role in the etiology of depression. Patients with metastatic cancer demonstrate elevated prevalence rates for depression. The objective of the current study was to illustrate the efficacy of interleukin-6 (IL-6) and HPA axis function as adjuncts to support the diagnosis of depression in cancer patients.

METHODS

Plasma concentrations of IL-6 and cortisol were measured in 114 cancer patients with and without depression. The relative diurnal variation of cortisol (cortisol VAR), expressed as a percentage, was calculated. Receiver operating characteristics analysis was performed.

RESULTS

Depression was associated with increased plasma concentrations of IL-6 (18.7 pg/mL vs. 2.7 pg/mL; P < .001) and higher cortisol concentrations at 8 AM and 8 PM. The relative cortisol VAR (11.7% vs. 60.6%, respectively; P < .001) was found to be decreased in cancer patients with depression, indicating a disturbed circadian function of the HPA axis. As a biomarker of depression, IL-6 yielded at a cutoff value of 10.6 pg/mL, a sensitivity of 79%, and a specificity of 87% (area under the curve [AUC] = 0.86; 95% confidence interval [95% CI], 0.78-0.94), whereas cortisol VAR demonstrated a sensitivity of 81% and a specificity of 88% (AUC = 0.85; 95% CI, 0.74-0.97) at a cutoff value of 33.5%.

CONCLUSIONS

Depression is associated with increased plasma IL-6 concentrations in patients with cancer. These patients demonstrate a dysfunction of the HPA-axis, characterized by a decreased diurnal variation of cortisol. The high sensitivity and specificity of these parameters biomarkers of depression make IL-6 and cortisol VAR helpful tools in the diagnosis of depression in patients with cancer.

Lymphocyte subsets and viral load in male AIDS patients with major depression: naturalistic study

This study investigated the relationships between lymphocyte subsets and viral load in AIDS patients with and without major depression. During a 7-year period, a total of 60 male hospitalized AIDS patients were recruited in this study. The diagnosis of major depression in patients was made by the same psychiatrist according to the 4th edition of the Diagnostic and Statistical Manual for Mental Disorders criteria. All patients had data for CD4, CD8 and CD4/CD8, and only 42 patients had viral load data. Of 60 AIDS patients, 32 patients had received highly active antiretroviral therapy and received subsequent assessment of lymphocyte cell counts 1 month later. Using ancova with age adjustment, the authors found that patients with major depression (n = 22) had significantly lower CD8 cell counts than patients without major depression (n = 38). However, CD4 cell counts and CD4/CD8 ratios were not significantly different between these two groups. In addition, there was no significant difference in viral load between patients with major depression (n = 16) and patients without major depression (n = 26). Of 32 patients received highly active antiretroviral therapy, 14 patients with an antidepressant (e.g. fluoxetine 20 mg/day) had significantly decreased CD4 and not CD8 cell counts and significantly reduced CD4/CD8 ratios during a period of 1 month. In conclusion, these results suggest that AIDS patients with major depression had significantly lower CD8 cell counts and might have a more severe inflammation/immunity reaction than patients without major depression.

Dental plaque, gingival inflammation, and elevated levels of interleukin-6 and cortisol in gingival crevicular fluid from women with stress-related depression and exhaustion

BACKGROUND

The aim of the present study was to investigate the importance of stress for the development of periodontitis by comparing oral health status, proinflammatory markers, and cortisol in gingival crevicular fluid (GCF) and saliva in patients with stress-related mental depression and controls.

METHODS

The participants consisted of 43 women with stress-related depression and exhaustion (Diagnostic and Statistical Manual of Mental Disorders, 4th edition [DSM-IV], with a mean age of 42.0 (+/- 9.3 SD) years, and 29 controls, with a mean age of 54.5 (+/- 2.9 SD) years. Clinical examination included the assessment of dental plaque, gingival inflammation (GI), bleeding on probing (BOP), probing depth (PD), clinical attachment level (CAL), and number of teeth. GCF was collected with an intracrevicular washing technique from four sites in each subject. Interleukin (IL)-1beta, IL-6, and matrix metalloproteinase-9 were determined with enzyme-linked immunosorbent assay and cortisol with radioimmunoassay (125I RIA). Analysis of covariance (one-way covariance analyses) was used to remove the influence of age and smoking.

RESULTS

The amount of plaque was significantly higher in patients compared to controls (P<0.003). The patients had an average GI of 1.53 (+/-0.13 SD) compared to 0.89 (+/- 0.10 SD) for the controls (P< 0.001). The levels of cortisol in GCF was significantly higher in patients than in controls, 3.46 nmol/l (+/- 3.25 SD) and 0.30 nmol/l (+/- 0.25 SD), respectively (P<0.001), whereas cortisol in saliva did not differ between groups. The levels of IL-6 in GCF were significantly higher in the patients than in controls (P<0.05).

CONCLUSION

Women with stress-related depression and exhaustion had more plaque accumulation, GI and increased levels of IL-6 and cortisol in GCF compared to normal controls, suggesting that depression might affect immune function, which could lead to impaired periodontal health.

Changes in the immune system in depression and dementia: causal or coincidental effects?

Epidemiological studies show that there is a correlation between chronic depression and the likelihood of demential in later life. There is evidence that inflammatory changes in the brain are pathological features of both depression and dementia. This suggests that an increase in inflammation-induced apoptosis, together with a reductin in the synthesis of neurotrophic factors caused by a rise in brain glucocorticoids, may play a role in the pathology of these disorders. A reduction in the neuroprotective components of the kynurenine pathway, such as kynurenic acid, and an increase in the neurodegenerative components, 3-hydroxykynurenine and quinolinic acid, contribute to the pathological changes. Such changes are postulated t cause neuronal damage, and thereby predispose chronically depressed patients to demential.

Neuroimmune-endocrine crosstalk in schizophrenia and mood disorders

This review focuses on possible causes and the impact of different immune states in schizophrenia and major depression. It discusses the fact that, in schizophrenia, an over-activation of the type 2 immune response may dominate, while the type 1 and the pro-inflammatory immune responses are over-activated in major depression. The consequence of these diverse immune states is the activation and, respectively, inhibition of different enzymes in tryptophan/kynurenine metabolism, which may lead to an overemphasis of N-methyl-D-aspartate (NMDA) receptor antagonism in schizophrenia and of NMDA-receptor agonism in depression, resulting in glutamatergic hypofunction in schizophrenia and glutamatergic hyperfunction in major depression. In addition, the activation of the type 1 and the pro-inflammatory immune responses in major depression result in increased serotonin degradation and a serotonergic deficit. While antipsychotics and antidepressants today mainly act on the dopaminergic-glutamatergic and the noradrenergic-serotonergic neurotransmission, anti-inflammatory and immune-modulating therapies might act more basically at the pathophysiological mechanism. The limitations of this concept, however, are critically discussed.

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

Signs of an inflammatory process, in particular increased pro-inflammatory cytokines and increased levels of prostaglandine E(2) (PGE(2)), have repeatedly been described in major depression (MD). As cyclooxygenase-2 (COX-2) inhibitors inhibit the PGE(2) production and the production of pro-inflammatory cytokines, we performed a therapeutic trial with the COX-2 inhibitor celecoxib. In a prospective, double-blind, add-on study, 40 patients suffering from an acute depressive episode were randomly assigned to either reboxetine and celecoxib or to reboxetine plus placebo. After a wash-out period, 20 patients received 4-10 mg reboxetine plus placebo and 20 received reboxetine plus 400 mg celecoxib for 6 weeks. The treatment effect was calculated by analysis of variance. There were no significant differences between groups in age, sex, duration or severity of disease or psychopathology, or reboxetine dose or plasma levels. Over 6 weeks, both groups of patients showed significant improvement in scores of the Hamilton Depression Scale. However, the celecoxib group showed significantly greater improvement compared to the reboxetine-alone group. Additional treatment with celecoxib has significant positive effects on the therapeutic action of reboxetine with regard to depressive symptomatology. Moreover, the fact that treatment with an anti-inflammatory drug showed beneficial effects on MD indicates that inflammation is related to the pathomechanism of the disorder, although the exact mechanisms remain to become elucidated.

Baseline immune activation as a risk factor for the onset of depression during interferon-alpha treatment

BACKGROUND

Major depression has been associated cross-sectionally with increased cell-mediated immune activation but causality has been difficult to establish. This study prospectively investigated the hypothesis that baseline level of immune activation predicts the development of depression during interferon-alpha (IFN-alpha) treatment.

METHODS

Sixteen hepatitis C patients without psychiatric disorder underwent IFN-alpha treatment. Proinflammatory and anti-inflammatory cytokines were determined before starting treatment. Presence of a major depressive disorder (MDD) was assessed at baseline and several times during treatment.

RESULTS

Baseline soluble interleukin-2 receptor (sIL-2r), interleukin-6 (IL-6), and interleukin-10 (IL-10) concentrations were significantly increased in the five subjects that developed MDD during treatment compared with those that did not, with standardized effect sizes of 1.08, 1.16, and 1.25, respectively, controlling for marijuana use, cigarette smoking, and baseline level of depressive symptoms.

CONCLUSIONS

Results suggest that increased immune activation, rather than an epiphenomenon, is a causal risk factor for the development of MDD.

Psychophysiological and cortisol responses to psychological stress in depressed and nondepressed older men and women with elevated cardiovascular disease risk

OBJECTIVE

The objective of this study was to compare psychophysiological and cortisol reactions to psychological stress in older depressed and nondepressed patients at risk for cardiovascular disease (CVD).

METHODS

Forty-eight depressed participants and 20 controls with elevated cardiovascular risk factors underwent a psychological stress test during which cardiovascular variables were measured. Salivary cortisol was collected after each test segment. Traditional (e.g., lipids) and atypical (e.g., C-reactive protein) CVD risk factors were also obtained.

RESULTS

At baseline, the groups did not differ on lipid levels, flow-mediated vasodilation, body mass index, or asymmetric dimethylarginine. However, the depressed patients had significantly higher C-reactive protein levels. Contrary to our hypothesis, there were no differences in baseline cortisol levels or diurnal cortisol slopes, but depressed patients showed significantly lower cortisol levels during the stress test (p = .03) and less cortisol response to stress. Compared with nondepressed subjects, depressed subjects also showed lower levels of respiratory sinus arrhythmia (RSA(TF)) during the stress test (p = .02).

CONCLUSIONS

In this sample, older depressed subjects with elevated risk for CVD exhibited a hypocortisol response to acute stress. This impaired cortisol response might contribute to chronic inflammation (as reflected in the elevated C-reactive proteins in depressed patients) and in other ways increase CVD risk. The reduced RSA(TF) activity may also increase CVD risk in depressed patients through impaired autonomic nervous system response to cardiophysiological demands.

Effects of mood state and psychosocial functioning on plasma Interleukin-6 in adult patients before cardiac surgery

OBJECTIVE

The purpose of this study was to examine the potential effect of mood states and psychosocial functioning during the waiting weeks prior to major cardiac surgery on the plasma Interleukin-6 (IL-6) levels in 236 patients immediately before their operation.

METHOD

The sample was recruited from patients at the cardiac clinic of the University of Michigan Medical Center (Ann Arbor). Two weeks before cardiac surgery, trained research assistants conducted a face-to-face interview with these middle-aged and older patients on their preoperative physical examination date at the clinic. Standardized instruments were used to assess mood states and psychosocial functioning. The blood samples of 236 patients, obtained on the morning of the operation, were analyzed for plasma IL-6.

RESULTS

In bivariate analysis, poor psychological functioning and anxiety, as well as bodily pain and body mass index (BMI), were correlated with plasma IL-6 (p < .05), but sociodemographics, chronic illness and use of psychotropic medications were not. When the effect of bodily pain and BMI were taken into account, partial correlation analysis showed that psychological functioning continued to be associated with plasma IL-6 (p < .05); the association of IL-6 with depression now became significant (p < .05), whereas that with anxiety became even more significant (p < .001).

CONCLUSIONS

Preoperative psychological disturbances during the waiting weeks before cardiac surgery may influence the plasma levels of IL-6 immediately prior to the procedure. The clinical implications of these findings remain to be determined.

Depression as a risk factor for the onset of type 2 diabetes mellitus. A meta-analysis

AIMS/HYPOTHESIS

Evidence strongly suggests that depression and type 2 diabetes are associated, but the direction of the association is still unclear. Depression may occur as a consequence of having diabetes, but may also be a risk factor for the onset of type 2 diabetes. This study examined the latter association by reviewing the literature and conducting a meta-analysis of longitudinal studies on this topic.

METHODS

Medline and PsycInfo were searched for articles published up to January 2005. All studies that examined the relationship between depression and the onset of type 2 diabetes were included. Pooled relative risks were calculated using fixed and random effects models. To explore sources of heterogeneity between studies, subgroup analyses and meta-regression analyses were performed.

RESULTS

Nine studies met our inclusion criteria for this meta-analysis. The pooled relative risk was 1.26 (1.13-1.39) using the fixed effects model and 1.37 (1.14-1.63) using the random effects model. Heterogeneity between studies could not be explained by (1) whether studies controlled for undetected diabetes at baseline; (2) the method of diabetes assessment at follow-up; (3) the baseline overall risk of diabetes in the study population; and (4) follow-up duration.

CONCLUSIONS/INTERPRETATION

Depressed adults have a 37% increased risk of developing type 2 diabetes mellitus. The pathophysiological mechanisms underlying this relationship are still unclear and warrant further research. A randomised controlled study is needed to test whether effective prevention or treatment of depression can reduce the incidence of type 2 diabetes and its health consequences.

Study protocol to investigate the effect of a lifestyle intervention on body weight, psychological health status and risk factors associated with disease recurrence in women recovering from breast cancer treatment [ISRCTN08045231]

BACKGROUND

Breast cancer survivors often encounter physiological and psychological problems related to their diagnosis and treatment that can influence long-term prognosis. The aim of this research is to investigate the effects of a lifestyle intervention on body weight and psychological well-being in women recovering from breast cancer treatment, and to determine the relationship between changes in these variables and biomarkers associated with disease recurrence and survival.

METHODS/DESIGN

Following ethical approval, a total of 100 patients will be randomly assigned to a lifestyle intervention (incorporating dietary energy restriction in conjunction with aerobic exercise training) or normal care control group. Patients randomised to the dietary and exercise intervention will be given individualised healthy eating dietary advice and written information and attend moderate intensity aerobic exercise sessions on three to five days per week for a period of 24 weeks. The aim of this strategy is to induce a steady weight loss of up to 0.5 Kg each week. In addition, the overall quality of the diet will be examined with a view to (i) reducing the dietary intake of fat to approximately 25% of the total calories, (ii) eating at least 5 portions of fruit and vegetables a day, (iii) increasing the intake of fibre and reducing refined carbohydrates, and (iv) taking moderate amounts of alcohol. Outcome measures will include body weight and body composition, psychological health status (stress and depression), cardiorespiratory fitness and quality of life. In addition, biomarkers associated with disease recurrence, including stress hormones, estrogen status, inflammatory markers and indices of innate and adaptive immune function will be monitored.

DISCUSSION

This research will provide valuable information on the effectiveness of a practical, easily implemented lifestyle intervention for evoking positive effects on body weight and psychological well-being, two important factors that can influence long-term prognosis in breast cancer survivors. However, the added value of the study is that it will also evaluate the effects of the lifestyle intervention on a range of biomarkers associated with disease recurrence and survival. Considered together, the results should improve our understanding of the potential role that lifestyle-modifiable factors could play in saving or prolonging lives.

Interleukin-6 genetic polymorphism and Chinese major depression

BACKGROUND

It has been reported that serum concentrations of interleukin-6 (IL-6), a pro-inflammatory cytokine, were significantly higher in major depressive disorder (MDD).

OBJECTIVES

The aim of the present study was to examine whether the IL-6 genetic variant confers susceptibility to MDD.

METHODS

We genotyped a functional polymorphism in the promoter region (position -634) of the IL-6 gene in a sample of 257 MDD patients and 105 normal controls.

RESULTS

No significant differences were demonstrated for the genotype or allele frequency of the IL-6 polymorphism when comparing the MDD and control groups.

CONCLUSIONS

Our findings suggested that the investigated IL-6 polymorphism does not affect MDD susceptibility. We propose that other genetic variations of IL-6, relating either to MDD or to the clinical manifestations of MDD, may need further investigation.

Social isolation and the inflammatory response: sex differences in the enduring effects of a prior stressor

Numerous epidemiological studies have demonstrated an association between persistent social isolation and “all-cause” morbidity and mortality. To date, no causal mechanism for these findings has been established. Whereas animal studies have often reported short-term effects of social isolation on biological systems, the long-term effects of this adverse psychological state have been understudied. This is the first animal study to examine the effects of long-term social isolation from weaning through young adulthood on an innate inflammatory response linked to numerous disease processes. Results presented here offer a plausible link between vulnerability to disease and social neglect. For socially isolated male and female Sprague-Dawley rats, a naturally gregarious species, formation of a granuloma in response to a subcutaneous injection of carrageenin (seaweed) was significantly delayed compared with the response of animals housed in single-sex groups of five. Significant sex differences, however, emerged when an acute prior stressor was superimposed on the experience of chronic social isolation. In this context, isolated females produced a more robust inflammatory response than isolated males. This sexual dimorphism at the nexus of chronic social isolation, acute stress, and inflammatory processes may account for the observation in humans that men with low levels of social integration are more vulnerable to disease and death than women.

Noradrenaline transporter and its turnover rate are decreased in blood lymphocytes of patients with major depression

Lymphocytes possess transporters of serotonin and dopamine, and also contain monoamines. The objective of this work was to determine the presence of noradrenaline transporters, the turnover rate of noradrenaline and serotonin in lymphocytes of major depression patients, and to correlate the biochemical parameters with the severity of the disorder. Lymphocytes from peripheral blood were isolated by Ficoll/Hypaque, and noradrenaline transporter was studied by binding of [3H]nisoxetine: control group (29, age 31.52+/-1.08, 7 men) and major depression patients (35, age 36.68+/-1.69, 6 men), Hospital Vargas de Caracas. Diagnostic was done by criteria of the American Psychiatric Association and severity by Hamilton Scale for Depression. Levels of noradrenaline, serotonin, 3-methoxy-4-hydroxyphenylglycol and 5-hydroxyindoleacetic acid were determined by HPLC. Turnover rate was evaluated by the ratios of monoamines and metabolites. Correlations were done between the biochemical parameters and the severity of depression. The score of Hamilton for Depression was 22.77+/-0.51. There was a reduction in the number of transporters in lymphocytes of patients, 0.95+/-0.27 versus 4.06+/-1.67 fmol/10(6) cells. Levels of monoamines and metabolites did not significantly differ between patients and controls. However, there was a higher monoamine/metabolite ratio in lymphocytes of patients, indicating a reduction of metabolic turnover rate. Also there was a relative greater concentration of noradrenaline than serotonin in the lymphocytes of the patients, as indicated by the ratio noradrenaline/serotonin. Noradrenergic and serotonergic turnover is decreased in blood peripheral lymphocytes of major depression patients; the reduction in noradrenaline transporter could be related to changes in intracellular levels, and these modifications could result in functional changes of the immune system.

Evidence-informed assessment and treatment of depression in HCV and interferon-treated patients

More than 4 million people are currently infected with Hepatitis C an RNA virus that may ultimately result in complete hepatic failure and is often a silent infection until late in the course of disease. Hepatitis C patients have increased rates of major depression (as well as substance abuse) and treatment of hepatitis with interferon, the current standard treatment, provokes episodes of depression in as many as a third of patients treated. Immune-dysfunction mediated mechanisms for the depression in these patients have been proposed and have increasing experimental support. The resulting depression has interfered with treatment for many patients, but several standard treatments for depression have been shown to be effective in patients with interferon-associated depression, suggesting that this should not be a barrier to effective treatment. In this paper, we review the evidence for associations between depression and Hepatitis C and interferon treatment, as well as the evidence supporting an immune mechanism for the association, and finally the data showing effective treatment and recommendations for prophylactic use of anti-depressants.

Cytokines sing the blues: inflammation and the pathogenesis of depression

Increasing amounts of data suggest that inflammatory responses have an important role in the pathophysiology of depression. Depressed patients have been found to have higher levels of proinflammatory cytokines, acute phase proteins, chemokines and cellular adhesion molecules. In addition, therapeutic administration of the cytokine interferon-alpha leads to depression in up to 50% of patients. Moreover, proinflammatory cytokines have been found to interact with many of the pathophysiological domains that characterize depression, including neurotransmitter metabolism, neuroendocrine function, synaptic plasticity and behavior. Stress, which can precipitate depression, can also promote inflammatory responses through effects on sympathetic and parasympathetic nervous system pathways. Finally, depression might be a behavioral byproduct of early adaptive advantages conferred by genes that promote inflammation. These findings suggest that targeting proinflammatory cytokines and their signaling pathways might represent a novel strategy to treat depression.

Clinical depression and regulation of the inflammatory response during acute stress

OBJECTIVE

This study examined whether clinical depression is associated with a differential inflammatory response to an acute bout of psychological stress.

METHODS

A total of 72 women participated in the study; half met diagnostic criteria for clinical depression; the others had no history of psychiatric illness. The groups were matched with respect to age and ethnicity. All subjects were exposed to a 17-minute mock-job interview; blood was drawn to assess secretion and regulation of inflammatory molecules.

RESULTS

The stressor was associated with feelings of shame and anxiety, a mobilization of monocytes, neutrophils, and C-reactive protein into the circulation, and greater endotoxin-stimulated production of interleukin-6 and tumor necrosis factor-alpha by white blood cells in vitro. Depressed subjects began the session with greater sensitivity to the antiinflammatory properties of glucocorticoids than control subjects. Following exposure to the stressor protocol, however, sensitivity decreased among depressed subjects and increased among controls. This was manifest by disparities in interleukin-6 and tumor necrosis factor-alpha production in the presence of dexamethasone.

CONCLUSIONS

These findings suggest that under acutely challenging conditions, depression is associated with greater resistance to molecules that normally terminate the inflammatory cascade. An impaired capacity to regulate inflammation could underlie some of the excess morbidity and mortality that has been associated with depression.

Different activation patterns of proinflammatory cytokines in melancholic and non-melancholic major depression are associated with HPA axis activity

BACKGROUND

Recent studies showed an activation of the cytokine system and the HPA axis in major depression, although with inconsistent results. While the non-melancholic subtype displayed a proinflammatory cytokine pattern, the melancholic subtype showed signs of impaired cytokine production. In order to understand the potential pathogenic significance of these systems further, the interplay between the cytokine system and the HPA axis in depressive subtypes as well as potential changes of these systems during the course of disease were investigated.

METHODS

N=37 initially unmedicated patients with acute major depression were sub-classified (melancholic vs. non-melancholic) and compared with N=37 matched healthy controls. Upon admission and after complete clinical remission, basal plasma ACTH and serum cortisol levels as well as cytokine productions (IL-1beta, IL-1 receptor antagonist (IL-1RA)) upon mitogen stimulation (PHA) were measured in a whole blood assay.

RESULTS

ACTH and cortisol concentrations were significantly elevated on admission in the melancholic but not the non-melancholic subgroup. Non-melancholic patients produced significantly more IL-1beta and IL-1RA upon admission than controls or melancholic patients. The IL-1 RA/IL-1beta ratio was significantly lower in the non-melancholic compared to the melancholic subgroup and increased significantly upon remission.

LIMITATIONS

Patient treatment was not standardized. No Dex/CRH test was performed.

CONCLUSIONS

Melancholic patients demonstrated an activation of the HPA axis in acute stage with partial normalization upon remission but no signs of inflammation. Non-melancholic patients showed signs of inflammation in acute depression with normalization upon remission while the function of the HPA axis was normal.

Depressive symptoms and inflammation among heart failure patients

BACKGROUND

Psychological depression has been linked to heart failure, both an antecedent to and as a risk factor for poor outcomes among patients with existing heart failure. Elevated levels of proinflammatory cytokines have been proposed as a possible physiological link between the 2 conditions. The objective of this study was to examine the proinflammatory cytokines interleukin (IL)-6, IL-1beta, and tumor necrosis factor-alpha (TNFalpha) in heart failure patients with and without elevated symptoms of depression.

METHODS

Thirty-two heart failure patients were recruited from an outpatient heart failure clinic. Depressive symptoms were measured with the Beck Depression Inventory (BDI), and a patient was classified as having elevated symptoms of depression if he/she scored > or = 10. The cognitive-affective subscale score of the BDI, which measures depressed mood independent of physical symptoms, was also examined.

RESULTS

In the multiple linear regression models controlling for age, sex, smoking, and antidepressant medication use, there was no relation between BDI score and IL-6 (P = .7612) or IL-1beta (P = .8261). However, there was a statistically significant positive relation between BDI score and TNFalpha (P = .0374). There was also a significant relation between an elevated cognitive-affective score and TNFalpha (P = .0322) but no association with IL-6 (P = .8593) or IL-1beta (P = .3737).

CONCLUSIONS

The association between TNFalpha and the cognitive-affective subscale, which eliminates the physical signs and symptoms that are shared by depression and heart failure, demonstrates a depression-specific activation of proinflammatory cytokines that may promote disease progression and mortality in patients with heart failure.

Overview of the field

Clinical descriptions of depression date back to antiquity. Scientific investigations of mood disorders started only 150 years ago. An historical overview of depression leads into today's knowledge that depressive disorders are common, serious, and sometimes life-threatening and that their effects are persistent and costly. Depressive disorders have a high prevalence, around 5% in the general population, with at least 20% of patients suffering with chronic conditions, such as cardiovascular disease and diabetes. Neuroimaging technology provides unprecedented opportunities for elucidating the neurobiological correlates of mood disorders. Neuroimaging studies of primary mood disorders have identified neurophysiologic abnormalities in the orbital and medial prefrontal cortex (PFC), the amygdala, and the related parts of the striatum and thalamus. There has been a revolution in our understanding of the pathogenesis of depression, with recent work demonstrating, among others, the critical impact of stress. There is an abundant evidence from family, twin, and adoption studies that genetic factors play an important role in the etiology of affective disorders. A variety of hormonal abnormalities, such as altered levels of cortisol, growth hormone, or thyroid hormones, indicate the existence of endoctrine disturbances. Despite the initial findings of immunosuppresion in depression, some studies have indicated that immune activation could also be present and might even play a role in the onset of depressive symptoms. Neurotrophic factors are among the growth factors that have been studied for their role in the adult nervous system. Despite advances in the pharmacotherapy of depression, only one third of patients respond favorably to antidepressant drugs. One third do not respond at all, and in clinical trials, at least one third respond to placebo. There is clearly an urgent need for novel antidepressants.

Inflammatory markers in depressed post-myocardial infarction patients

BACKGROUND

Depressive disorder in the post-myocardial infarction (MI) period has been associated with increased cardiac morbidity and mortality. Possible pathophysiological mechanisms behind this association are not clear. Major depression in physically healthy subjects has been related to immune abnormalities including increased plasma levels of interleukin-6 (IL-6), tumor necrosis factor alfa (TNF-alpha) and C-reactive protein (CRP). In patients with MI, increased inflammatory markers, such as CRP and TNF-alpha, have been associated with increased cardiovascular events. It was the aim of this study to test the hypothesis that depression in post-MI patients is associated with increased inflammation as compared to non-depressed post-MI patients.

METHODS

The cytokines IL-6 and TNF-alpha ; the soluble cytokine receptors sIL-6R, sTNF-RI and sTNF-RII; neopterin; and the inflammation-sensitive plasma proteins (ISPs) CRP and haptoglobin were assessed in a group of 57 patients with a diagnosis of depression post-MI and in a control group of 46 non-depressed post-MI patients, matched for age, gender and time elapsed since MI.

RESULTS

Cytokine, neopterin and ISP levels were not statistically different in the depressed post-MI group as compared to the non-depressed post-MI group. Several inflammatory markers were however elevated in both cohorts when compared with levels reported in healthy subjects, indicating persistent inflammation several months after MI.

CONCLUSIONS

There was no indication of increased inflammation in depressed post-MI patients as compared to non-depressed post-MI patients.

Religious participation, interleukin-6, and mortality in older adults

This study prospectively examined the relationship between religious attendance, interleukin-6 (IL-6) levels, and mortality rates in a community-based sample of 557 older adults. Attending religious services more than once weekly was a significant predictor of lower subsequent 12-year mortality and elevated IL-6 levels (> 3.19 pg/mL), with a mortality ratio of.32 (95% confidence interval [CI] = 0.15,0.72; p <.01) and an odds ratio for elevated IL-6 of.34 (95% CI = 0.16, 0.73, p <.01), compared with never attending religious services. Structural equation modeling indicated religious attendance was significantly related to lower mortality rates and IL-6 levels, and IL-6 levels mediated the prospective relationship between religious attendance and mortality. Results were independent of covariates including age, sex, health behaviors, chronic illness, social support, and depression. Findings are consistent with a role for IL-6 in processes mediating the relationship between religious attendance and mortality.

Association of a corticotropin-releasing hormone receptor 1 haplotype and antidepressant treatment response in Mexican-Americans

There are well-replicated, independent lines of evidence supporting a role for corticotropin-releasing hormone (CRH) in the pathophysiology of depression. CRH receptor 1 (CRHR1), which we first mapped in the brain in 1994, has been implicated in the treatment of depression and anxiety. We studied the association of CRHR1 genotypes with the phenotype of antidepressant treatment response in 80 depressed Mexican-Americans in Los Angeles who completed a prospective randomized, placebo lead-in, double-blind treatment of fluoxetine or desipramine, with active treatment for 8 weeks. Subjects were included into the study if they had a diagnosis of depression without other confounding medical or psychiatric diagnoses or treatments. All patients were followed weekly and assessed for changes in the Hamilton rating scales for anxiety (HAM-A) and depression (HAM-D). Inclusion criteria in the study included a HAM-D of 18 or higher. Because CRHR1 affects both depression and anxiety. Patients were classified into a high-anxiety (HA) group if their HAM-A score was 18 or higher and in a low-anxiety (LA) group if their HAM-A score was less than 18. Utilizing the haplotype-tag single-nucleotide polymorphisms rs1876828, rs242939 and rs242941, we tested for haplotypic association between CRHR1 and 8-week response to daily antidepressant treatment. In the HA group (n=54), homozygosity for the GAG haplotype was associated with a relative 70% greater reduction in HAM-A scores compared to heterozygous (63.1+/-4.5 vs 37.1+/-6.9%, respectively, P=0.002). For HAM-D, GAG haplotype homozygosity was associated with a 31% greater reduction in scores after treatment compared to heterozygous (67.3+/-4.3 vs 51.2+/-6.0%, respectively, P=0.03). In those with lower-anxiety levels at screening, there were no associations between CRHR1 genotype and percent change in HAM-A or HAM-D. These findings of increased response to antidepressants in highly anxious patients homozygous for the GAG haplotype of CRHR1 need to be independently validated and replicated. Such work would support the hypotheses that response to antidepressant treatment is heterogeneous and that the CRHR1 gene and possibly other genes in stress-inflammatory pathways are involved in response to antidepressant treatment. These findings also suggest that variations in the CRHR1 gene may affect response to CRHR1 agonists or antagonists. All data are deposited in www.pharmgkb.org.

Cytokine production in bipolar affective disorder patients under lithium treatment

BACKGROUND

Our knowledge concerning immune functioning in bipolar affective disorder (BAD) is limited, while lithium's immunomodulatory effects seem multiple and conflicting. Our aim was to evaluate cytokine production and lithium's effect on it in BAD patients, using ELISPOT technique as a sensitive tool.

METHODS

Cytokine (IL-2, IL-6, IL-10 and IFN-gamma) production from isolated peripheral blood lymphocytes (PBLs) was evaluated (ELISPOT technique) in 40 euthymic BAD patients under chronic lithium treatment, in 20 healthy volunteers, and in 10 never medicated BAD patients before and after the introduction of lithium therapy. In all cases, cytokine plasma levels were also measured using ELISA.

RESULTS

BAD patients under chronic lithium treatment had significantly lower numbers of IL-2, IL-6, IL-10 and IFN-gamma secreting cells compared to healthy volunteers. The number of cytokine secreting cells decreased in never medicated patients after 3 months of lithium treatment. In vitro stimulation of PBLs with lithium did not affect the number of cytokine secreting cells either in the patients or in the healthy volunteers.

CONCLUSIONS

The significantly lower number of PBLs producing cytokines (IL-2, IL-6, IL-10 and IFN-gamma) in euthymic BAD patients under chronic lithium treatment result from the long-term (over 3 months) lithium administration. In vitro stimulation of PBLs with lithium did not change the number of cytokine producing cells. Our findings may be useful in elucidating possible downregulatory effects of lithium in humans.

Invited review: the evolution of antidepressant mechanisms

Present antidepressants are all descendents of the serendipitous findings in the 1950s that the monoamine oxidase inhibitor iproniazid and the tricyclic antidepressant imipramine were effective antidepressants. The identification of their mechanism of action, and those of reserpine and amphetamine, in the 1960s, led to the monoamine theories of depression being postulated; first, with noradrenaline then 5-hydroxytryptamine being considered the more important amine. These monoamine theories of depression predominated both industrial and academic research for four decades. Recently, in attempts to design new drugs with faster onsets of action and more universal therapeutic action, downstream alterations common to current antidepressants are being examined as potential antidepressants. Additionally, the use of animal models has identified a number of novel targets some of which have been subjected to clinical trials in humans. However, monoamine antidepressants remain the best current medications and it may be some time before they are dislodged as the market leaders.

Immunologic variables in acute mania of bipolar disorder

Macrophages, lymphocytes and their products, may be involved in the pathophysiology of psychiatric disorders. The cell-mediated immune activation response of manic patients during pre-medication and medication stages remains unclear. The purpose of this case-control study was to investigate the plasma levels of immunologic variables, including interleukin (IL)-1 receptor antagonist (IL-1RA), soluble CD 4 (sCD4) and sCD8, and TH1 (interferon [IFN]-gamma and IL-2) and TH2 (IL-4 and IL-10) cytokines in patients with pre-medicated, medicated bipolar mania. The study subjects, aged 16-44 years, were physically healthy patients with Young Mania Rating Scale (YMRS) scores > or =26, and normal controls, aged 19-40 years, were matched for sex. The immune variables were measured in acute mania and in consequent remission (YMRS scores < or =12) among bipolar patients. The plasma levels of IL-1RA, sCD4, and sCD8 were found significantly increased in pre-medicated acute manic patients as compared to normal controls. But only IL-1RA and sCD8 were found different in remitted bipolar patients as compared to normal controls. For TH1 cytokines, culture supernatant level of IFN-gamma was found significantly lower in manic patients of both acute and remission stages as compared to normal controls. No significant difference was found in IL-2 level in pre-medicated acute manic patients compared to controls. For TH2 cytokines, no significant differences in IL-4 and IL-10 levels were observed. We showed that cell-mediated immune response was activated in patients with bipolar disorder during the pre-medication, medication, and the remission stages. Our study findings suggest that the immune-modulation in patients with bipolar disorder may be abnormal.

Monocyte chemoattractant protein-1 (MCP1) promoter -2518 polymorphism may confer a susceptibility to major depressive disorder in the Korean population

We conducted a case-control association study of the monocyte chemoattractant protein-1 (MCP1) gene -2518 polymorphism in 90 patients with major depressive disorder. Genotyping was performed by polymerase chain reaction methods. We found significant differences in genotype and allele frequencies. The present study suggests that this polymorphism may confer a susceptibility to major depressive disorder in the Korean population.

Cytokine-serotonin interaction through IDO: a neurodegeneration hypothesis of depression

There are different theories and hypotheses related to the aetiology of depression. The interaction between brain 5-HT level and the activity of its autoreceptors plays a role in mood changes and depression. In major depression, activation of the inflammatory response system (IRS) and, increased concentrations of proinflammatory cytokines, prostaglandin E2 and negative immuno-regulatory cytokines in peripheral blood have been reported. Recently, pro-inflammatory cytokines have been found to have profound effects on the metabolism of brain serotonin through the enzyme indoleamine-2,3-dioxygenase (IDO) that metabolizes the tryptophan, the precursor of 5-HT to neurodegenerative quinolinate and neuroprotective kynurenate. The cytokine-serotonin interaction that leads to the challenge between quinolinate and kynurenate in the brain explains the neurodegeneration hypothesis of depression.

Socioeconomic status and stress-induced increases in interleukin-6

Coronary artery disease (CAD) is more prevalent in people from a low socioeconomic background, and low socioeconomic status (SES) is associated with an increased exposure to psychological stress. The pro-inflammatory cytokine interleukin-6 (IL-6) plays a central role in CAD development. IL-6 is responsive to psychological stress and could potentially mediate the effect of psychosocial factors on CAD risk. Accordingly, we predicted that people of low SES would have greater and/or more sustained IL-6 responses to acute psychological stress. Based on previous findings, we also predicted that these people would have delayed post-stress cardiovascular recovery. Thirty-eight male civil servants were tested, with participants divided into high and low SES groups according to employment grade. There were no differences between the groups at baseline. However there were significant differences in IL-6 and heart rate responses to stress. Stress induced increases in plasma IL-6 in all participants. However, in the low SES group, IL-6 continued to increase between 75 min and 2h post-stress, whereas IL-6 levels stabilised at 75 min in the high SES group. Heart rate increased to the same extent following stress in both groups, however by 2h post-stress, it had returned to baseline in 75% of the high SES group compared with only 38.1% of the low SES group. These results suggest that low SES people are less able to adapt to stress than their high SES counterparts. Prolonged stress-induced increases in IL-6 in low SES groups represents a novel mechanism potentially linking socioeconomic position and heart disease.

Cynical hostility, depressive symptoms, and the expression of inflammatory risk markers for coronary heart disease

Although the prognostic significance of depression and hostility has been established, little is known about how they operate together to influence disease processes. This study explored the independent and interactive relationships between these constructs and the expression of inflammatory markers implicated in the pathogenesis of coronary heart disease. One hundred adults completed measures of cynical hostility and depressive symptoms, and had blood drawn to assess serum levels of interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha. Depression was directly related to inflammatory markers, but hostility was not. A significant interaction between hostility and depression emerged. Among participants scoring low in depressive symptoms, hostility was positively associated with interleukin-6 and tumor necrosis factor-alpha concentrations. Hostility's association with these inflammatory markers was much weaker among participants with moderate depressive symptoms, however, and virtually nil among participants with severe depressive symptoms. Neither depression nor hostility was associated with interleukin-1 beta concentrations. These findings highlight the importance of considering both the independent and interactive relationships among psychosocial characteristics involved in disease.

Psychosocial factors in the development of coronary artery disease

The fact that traditional risk factors only account for approximately two thirds of cases of coronary artery disease (CAD) has stimulated increasing interest in the relationship between CAD and psychosocial factors. Five areas--chronic stress, socioeconomic status (SES), personality, depression, and social support--have been most thoroughly examined. There is evidence to support a causal relationship between chronic stress, SES, depression, and social support and development of CAD. In this article, we discuss the epidemiologic evidence linking psychosocial factors and CAD, and review the effects of psychosocial factors on several pathophysiologic mechanisms that have been proposed as potential mediators of CAD. The hypothalamic-pituitary-adrenal axis, hypertension and cardiovascular reactivity, endothelial function, inflammatory markers, platelets, coagulation factors, fibrinogen, lipids, glucose metabolism, and lifestyle factors have all been implicated in this process. Recently, the first intervention trials have been carried out, although with initially disappointing results. Reducing the cardiovascular risk due to these psychosocial factors will be one of the major health care challenges in the future.

Does neuroimmune dysfunction mediate seasonal mood changes in winter depression?

BACKGROUND

Animal studies have demonstrated seasonal changes in immune function mediated by nocturnal melatonin duration as a biological signal for photoperiod. Recent research has highlighted the potential role of neuroimmune dysfunction in depressive disorders. The etiology of winter depression (seasonal affective disorder, or SAD) is not known, but a number of studies have provided support for both photoperiod and neurotransmitter hypotheses.

HYPOTHESIS

A new hypothesis is presented that links the SAD data on melatonin, photoperiod, and neurotransmitters by proposing that seasonal increases in proinflammatory cytokines are critical in the pathophysiology of winter SAD.

TESTING THE HYPOTHESIS

In SAD patients, but not healthy subjects: proinflammatory cytokines will be increased and the Th1/Th2 balance will be shifted to the left in winter compared to summer; neuroimmune function will be correlated with nocturnal melatonin duration in SAD patients; and light treatment will correct neuroimmune dysfunction.

IMPLICATIONS OF THE HYPOTHESIS

Diagnostic tests for SAD may be developed using cytokine assays; neuroimmune dysfunction may be predictors of response to treatments; new treatments for SAD (immune or anti-inflammatory treatment) may be developed.

Behavioral changes in rats after acute, chronic and repeated administration of interleukin-1beta: relevance for affective disorders

BACKGROUND

Acute, peripheral and central administration of recombinant rat interleukin-1beta (IL-1beta) has been shown to decrease social exploration and locomotor activity and to induce alterations in brain biogenic amines in rats. The aims of this study were to examine whether acute, repeated and chronic administration of IL-1beta to rats may interfere with shuttle box escape learning, a model for anxiety- and depression-like behavior.

METHODS

Sixty-four adult male viral-free Sprague-Dawley rats (200-300 g weight) housed in groups of four at 25 degrees C with a 12:12 light:dark cycle were used in the experiments. They were divided into 8 groups, i.e. 4 control and 4 experimental. The latter were divided into an acute group receiving a single intra-peritoneally (i.p.) challenge of IL-1beta (tested at the shuttle box 1 and 24 h later); a chronic group with daily i.p. injections of IL-1beta for 7 days (tested at the shuttle box 1 h later); and a group with repeated administration, i.e. one i.p. injection on the first day and a second challenge on the seventh day (tested at the shuttle box 1 h later). The control animals followed the same injecting and testing schedule but were treated i.p. with saline.

RESULTS

The acute group treated with one IL-1beta challenge and tested 1 (P=0.001) and 24 h (P=0.002) later showed significant time elongations in the escape trials. The animals treated chronically with IL-1beta for seven consecutive days showed a significant increase in the latency at the escape trials (P=0.0001). Repeated administration of IL-1beta on the first day and a second on the seventh day did not significantly alter the time elongation in the escape trial.

DISCUSSION

Acute and chronic administration of IL-1beta significantly increase the latency of escape to a foot shock, whereas repeated IL-1beta administration does not induce a sensitization of these behavioral responses.

Cortisol responses to mild psychological stress are inversely associated with proinflammatory cytokines

Glucocorticoids can down-regulate immune activity, but acute stress has been reported to increase both cortisol and levels of plasma cytokines. We investigated individual differences in cortisol responses and their associations with proinflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1ra), cardiovascular activity, and mental health. Saliva samples and blood were taken from 199 healthy middle-aged participants of the Whitehall II cohort at baseline, immediately after stress and 45 min later. We defined the 40% of participants with the highest cortisol response to stress as the cortisol responder group and 40% with the lowest response as the cortisol non-responder group. Plasma IL-6 was higher and the IL-1ra response to stress was greater in the cortisol non-responder group. The cortisol non-responders showed lower heart rate variability than the cortisol responders. The cortisol responder group experienced more subjective stress during the tasks and reported more impaired mental health than the non-responders. We conclude that individual variations in neuroendocrine stress responsivity may have an impact on proinflammatory cytokines, and that both high and low cortisol stress responsiveness has potentially adverse effects.

Affective style and in vivo immune response: neurobehavioral mechanisms

Considerable evidence exists to support an association between psychological states and immune function. However, the mechanisms by which such states are instantiated in the brain and influence the immune system are poorly understood. The present study investigated relations among physiological measures of affective style, psychological well being, and immune function. Negative and positive affect were elicited by using an autobiographical writing task. Electroencephalography and affect-modulated eye-blink startle were used to measure trait and state negative affect. Participants were vaccinated for influenza, and antibody titers after the vaccine were assayed to provide an in vivo measure of immune function. Higher levels of right-prefrontal electroencephalographic activation and greater magnitude of the startle reflex reliably predicted poorer immune response. These data support the hypothesis that individuals characterized by a more negative affective style mount a weaker immune response and therefore may be at greater risk for illness than those with a more positive affective style.

Hypothesis: dysregulation of immunologic balance resulting from hygiene and socioeconomic factors may influence the epidemiology and cause of glomerulonephritis worldwide

Glomerular diseases show diverse epidemiological characteristics throughout the world, which has been suggested to be caused by differences in genetics of the underlying populations or environmental exposure to the putative antigens or agents that either trigger or induce the disease. Recently, an alteration in immune balance of the T helper 1 (T(H)1) and T helper 2 (T(H)2) subsets has been implicated as a mechanism to explain the relative increase in allergic diseases in industrialized nations. According to the Hygiene Hypothesis, overcrowding and poor hygiene early in life may protect from atopic diseases because exposure to microbes predisposes in favor of a T(H)1-dominant response. Conversely, dominance of the T(H)2 subset would be responsible for the increasing incidence of allergies. We present the hypothesis that this imbalance may help explain the predilection for membranoproliferative glomerulonephritis (GN) and mesangial proliferative GN to be associated with developing and/or poor nations, whereas immunoglobulin A nephropathy and minimal change disease are observed more commonly in industrialized nations. The implication of the Hygiene Hypothesis is that clinical expression of immune-mediated renal disease would depend on the prevailing T(H)1/T(H)2 balance, rather than the etiologic agent, and it may help explain the epidemiological pattern of glomerular diseases worldwide.

Plasma interleukin-6 is associated with psychological coronary risk factors: moderation by use of multivitamin supplements

The current study examined the relation of plasma IL-6 to anger, hostility, and severity of depressive symptoms as a function of multivitamin supplement use in 96 healthy, nonsmoking men (aged 18-46). Plasma IL-6 was independently associated with anger, hostility, and severity of depressive symptoms, as well as with a composite factor score, but only among nonusers. Among users, these associations were not significant. Multivitamin use was associated with lower plasma IL-6 levels, but only among men with high composite factor scores. Statistical adjustments for age, body mass index, resting diastolic blood pressure, fasting total cholesterol, high-density lipoprotein cholesterol, alcohol use, exercise frequency, and educational level did not alter these results. These data suggest that plasma IL-6 is elevated among healthy men characterized by a propensity for anger, a hostile disposition, and greater severity of depressive symptoms and that multivitamin supplements could ameliorate plasma IL-6 levels among these men.

Pathways linking depression, adiposity, and inflammatory markers in healthy young adults

Despite mounting evidence that depression increases risk for cardiovascular morbidity and mortality, little is known about the mechanisms responsible for this association. The current study examined the inter-relationships between depression, adiposity, and inflammatory molecules implicated in the pathogenesis of coronary heart disease. One hundred adults were enrolled. Half were clinically depressed; the others were matched controls with no history of psychiatric illness. All subjects were in excellent health, defined as having no acute infectious disease, chronic medical illness, or prescribed medication regimen. Structural equation modeling yielded support for a model in which depressive symptoms promote weight accumulation, which in turn activates an inflammatory response through two distinct pathways: expanded adipose tissue release of interleukin-6 and leptin-induced upregulation of interleukin-6 release by white blood cells (CFI =.99; NNFI =.99; RMSEA =.05). It did not support a sickness behavior model in which the inflammatory molecules arising from expanded adipose tissue promote depressive symptoms.

Influence of depressive mood on the association of CRP and obesity in 3205 middle aged healthy men

We studied concentrations of C-reactive proteins (CRP) in a population-based sample of 3204 men aged 45-74 years. Obesity was identified in 726 (23%) men (body mass index (BMI) >30 kg/m(2)). Stratification of the sample into three levels of depressive mood revealed a significant association between increased CRP in the obese sample with highest level of depression in comparison to the low level obese depression group (p=.013). The obesity x depression interaction was significant (p=.021). Multivariate analysis confirmed this effect after adjusting for possible confounding variables (age, high blood pressure, smoking, physical inactivity, low social class, and low alcohol intake) (p=.008). In the non-obese sample, there was no association between depressive mood and concentrations of CRP. These findings suggest a possible synergistic effect of obesity and depressive mood on chronic low level inflammation which may play a crucial role in the pathogenesis of atherosclerosis.

Chronic stress and age-related increases in the proinflammatory cytokine IL-6

Overproduction of IL-6, a proinflammatory cytokine, is associated with a spectrum of age-related conditions including cardiovascular disease, osteoporosis, arthritis, type 2 diabetes, certain cancers, periodontal disease, frailty, and functional decline. To describe the pattern of change in IL-6 over 6 years among older adults undergoing a chronic stressor, this longitudinal community study assessed the relationship between chronic stress and IL-6 production in 119 men and women who were caregiving for a spouse with dementia and 106 noncaregivers, with a mean age at study entry of 70.58 (SD = 8.03) for the full sample. On entry into this portion of the longitudinal study, 28 of the caregivers' spouses had already died, and an additional 50 of the 119 spouses died during the 6 years of this study. Levels of IL-6 and health behaviors associated with IL-6 were measured across 6 years. Caregivers' average rate of increase in IL-6 was about four times as large as that of noncaregivers. Moreover, the mean annual changes in IL-6 among former caregivers did not differ from that of current caregivers even several years after the death of the impaired spouse. There were no systematic group differences in chronic health problems, medications, or health-relevant behaviors that might have accounted for caregivers' steeper IL-6 slope. These data provide evidence of a key mechanism through which chronic stressors may accelerate risk of a host of age-related diseases by prematurely aging the immune response.

Mindfulness-based stress reduction in relation to quality of life, mood, symptoms of stress, and immune parameters in breast and prostate cancer outpatients

OBJECTIVES

This study investigated the relationships between a mindfulness-based stress reduction meditation program for early stage breast and prostate cancer patients and quality of life, mood states, stress symptoms, lymphocyte counts, and cytokine production.

METHODS

Forty-nine patients with breast cancer and 10 with prostate cancer participated in an 8-week MBSR program that incorporated relaxation, meditation, gentle yoga, and daily home practice. Demographic and health behavior variables, quality of life (EORTC QLQ C-30), mood (POMS), stress (SOSI), and counts of NK, NKT, B, T total, T helper, and T cytotoxic cells, as well as NK and T cell production of TNF, IFN-gamma, IL-4, and IL-10 were assessed pre- and postintervention.

RESULTS

Fifty-nine and 42 patients were assessed pre- and postintervention, respectively. Significant improvements were seen in overall quality of life, symptoms of stress, and sleep quality. Although there were no significant changes in the overall number of lymphocytes or cell subsets, T cell production of IL-4 increased and IFN-gamma decreased, whereas NK cell production of IL-10 decreased. These results are consistent with a shift in immune profile from one associated with depressive symptoms to a more normal profile.

CONCLUSIONS

MBSR participation was associated with enhanced quality of life and decreased stress symptoms in breast and prostate cancer patients. This study is also the first to show changes in cancer-related cytokine production associated with program participation.