Articles on Inflammation & Depression

Eller T. Vasar V. Shlik J. Maron E. Pro-inflammatory cytokines and treatment response to escitalopram in major depressive disorder. Progress in Neuro-Psychopharmacology & Biological Psychiatry. 32(2):445-50, 2008. Alterations in the immune system may have importance for the pathophysiology of depression. Several studies have linked increased production of pro-inflammatory cytokines to depression and depressive symptoms. There is growing evidence that antidepressive treatment may influence the production of pro-and anti-inflammatory cytokines. In the present study we aimed to find associations between the levels of soluble interleukin-2 receptor (sIL-2R), interleukin-8 (IL-8) and tumor necrosis factor alpha (TNF-alpha) and the response to antidepressant treatment in patients with major depression. Our study group consisted of 100 patients (35 males and 65 females) who were treated with escitalopram 10-20 mg/day for 12 weeks. Responders and non-responders were identified according to Montgomery-Asberg's Depression Rating Scale (MADRS) scores. The levels of cytokines were measured at baseline and at 4th and 12th week of the treatment and compared to cytokine concentrations in healthy volunteers (n=45; 19 males and 26 females). Our data indicated that a higher level of TNF-alpha might predict a non-response to treatment with escitalopram and that changes in concentrations of sIL-2R during the treatment were different in responders and non-responders.

Danese A. Moffitt TE. Pariante CM. Ambler A. Poulton R. Caspi A. Elevated inflammation levels in depressed adults with a history of childhood maltreatment. Archives of General Psychiatry. 65(4):409-15, 2008. CONTEXT: The association between depression and inflammation is inconsistent across research samples. OBJECTIVE: To test whether a history of childhood maltreatment could identify a subgroup of depressed individuals with elevated inflammation levels, thus helping to explain previous inconsistencies. DESIGN: Prospective longitudinal cohort study. SETTING: New Zealand. PARTICIPANTS: A representative birth cohort of 1000 individuals was followed up to age 32 years as part of the Dunedin Multidisciplinary Health and Development Study. Study members were assessed for history of childhood maltreatment and current depression. MAIN OUTCOME MEASURES: Inflammation was assessed using a clinically relevant categorical measure of high-sensitivity C-reactive protein (>3 mg/L) and a dimensional inflammation factor indexing the shared variance of continuous measures of high-sensitivity C-reactive protein, fibrinogen, and white blood cells. RESULTS: Although depression was associated with high levels of high-sensitivity C-reactive protein (relative risk,1.45; 95% confidence interval,1.06-1.99), this association was significantly attenuated and no longer significant when the effect of childhood maltreatment was taken into account. Individuals with current depression and a history of childhood maltreatment were more likely to have high levels of high-sensitivity C-reactive protein compared with control subjects (n = 27; relative risk, 2.07; 95% confidence interval, 1.23-3.47). In contrast, individuals with current depression only had a nonsignificant elevation in risk (n = 109; relative risk, 1.40; 95% confidence interval, 0.97-2.01). Results were generalizable to the inflammation factor. The elevated inflammation levels in individuals who were both depressed and maltreated were not explained by correlated risk factors such as depression recurrence, low socioeconomic status in childhood or adulthood, poor health, or smoking. CONCLUSIONS: A history of childhood maltreatment contributes to the co-occurrence of depression and inflammation. Information about experiences of childhood maltreatment may help to identify depressed individuals with elevated inflammation levels and, thus, at greater risk of cardiovascular disease.

Benson S. Janssen OE. Hahn S. Tan S. Dietz T. Mann K. Pleger K. Schedlowski M. Arck PC. Elsenbruch S. Obesity, depression, and chronic low-grade inflammation in women with polycystic ovary syndrome. Brain, Behavior, & Immunity. 22(2):177-84, 2008. BACKGROUND AND OBJECTIVE: Women with polycystic ovary syndrome (PCOS) present with multiple risk factors for cardiovascular diseases at a young age, including obesity and chronic low-grade inflammation. Since depression is common in PCOS, this study aimed to address whether depression correlates with indices of chronic low-grade inflammation beyond the association with obesity. METHODS: Serum concentrations of IL-6, the stimulated production of IFN-gamma, TNF-alpha, IL-2, IL-4, IL-5, and IL-10, leukocyte numbers, and hsCRP were analyzed in 57 PCOS patients and 28 healthy women, together with clinical parameters, including body mass index (BMI), testosterone, and insulin resistance (HOMA-IR), and psychological parameters, including Beck Depression Inventory (BDI) and health-related quality-of-life (SF-36) scores. RESULTS: PCOS patients demonstrated significantly increased hsCRP, IL-6, and leukocyte numbers. Group differences in IL-6 and leukocyte numbers, but not hsCRP, disappeared after controlling for BMI. The stimulated production of IFN-gamma, TNF-alpha, IL-2, IL-4, and IL-5 was significantly decreased, irrespective of BMI. In PCOS, hsCRP, IL-6, and leukocyte numbers were correlated with BMI, HDL, diastolic blood pressure, and with insulin resistance. On the other hand, no correlations were found with depression scores or with PCOS-specific endocrine abnormalities. In regression models, BMI was a significant predictor of the key immune markers, and explained a large amount of variance, whereas BDI was not included in either model. CONCLUSIONS: These data confirm that obesity plays a pivotal role in inflammatory processes relevant to cardiovascular risk in women with PCOS. However, even lean PCOS patients may display subtle alterations in specific aspects of immunity. Our findings did not support a correlation of depression with chronic low-grade inflammation in PCOS.

Maes M. The cytokine hypothesis of depression: inflammation, oxidative & nitrosative stress (IO&NS) and leaky gut as new targets for adjunctive treatments in depression. [Review] [32 refs] Neuroendocrinology Letters. 29(3):287-91, 2008. This paper hypothesizes that inflammatory, oxidative and nitrosative (IO&NS) pathways, and an increased translocation of LPS from gram-negative bacteria are causally related to depression following external (psychological) and internal (organic) stressors and that IO&NS pathways are novel targets for antidepressant development. We review that depression is accompanied by an inflammatory reaction as indicated by an increased production of pro-inflammatory cytokines, such as interleukin-1beta (IL-1beta), IL-6, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN)-gamma. These cytokines are stress-sensitive and may cause depressive behaviors. The latter may be induced by an increased catabolism of tryptophan, the precursor of serotonin, to neurotoxic TRYCATs (tryptophan catabolites along the indoleamine oxidase pathway). Inflammatory biomarkers are detected in animal models of depression. Newly developed animal models of depression are based on induced inflammation. Most if not all antidepressants have specific anti-inflammatory effects. Anti-inflammatory compounds may augment the clinical efficacy of antidepressants. Depression is also accompanied by an IgM-related (auto)immune response directed against disrupted lipid membrane components, such as phosphatidyl-inositol, by-products of lipid peroxidation, e.g. azelaic acid and malondialdehyde, and NO-modified amino-acids, which are normally not detected by the immune system but due to damage caused by O&NS have become immunogenic. Increased translocation of lipopolysaccharide from gram-negative bacteria, which may be induced by internal and external stressors, may further aggravate the induced IO&NS pathways.

Ware WR. Psychological stress, insulin resistance, inflammation and the assessment of heart disease risk. Time for a paradigm shift?. Medical Hypotheses. 71(1):45-52, 2008. There is growing evidence that the present risk assessment protocol for coronary heart disease appears to underestimate the risk in general and the presence and progression of atherosclerosis in particular. Little or no correlation has been found between the 10-year risk based on the Framingham model and the extent or progression of coronary calcification. In addition, a number of studies find the protocol based on current guidelines leads to an under appreciation of the risk of symptomatic coronary heart disease or the associated fatal and non-fatal events, especially in younger asymptomatic individuals and women. Furthermore, the current guidelines give secondary importance to insulin resistance and inflammation and do not include psychosocial stress and depression, both of which are established and important risk factors for coronary heart disease. An alternative approach to risk assessment is proposed which emphasizes insulin resistance and psychological stress and depression and gives much greater recognition to inflammation as a root cause and target for intervention than is found in current guidelines. Consistent with this view, a revised assessment protocol is suggested which is still appropriate to the primary care setting and which might provide a different and perhaps more effective and relevant approach to primary prevention and risk reduction.

Muller N. Schwarz MJ. COX-2 inhibition in schizophrenia and major depression. [Review] [254 refs] Current Pharmaceutical Design. 14(14):1452-65, 2008.  In schizophrenia and depression, opposite patterns of type-1 - type-2 immune response seem to be associated with differences in the activation of the enzyme indoleamine 2,3-dioxygenase (IDO) and in the tryptophan - kynurenine metabolism resulting in increased production of kynurenic acid in schizophrenia and decreased production of kynurenic acid in depression. These differences are associated with an imbalance in the glutamatergic neurotransmission, which may contribute to an overweight of N-methyl-D-aspartate (NMDA) agonism in depression and of NMDA antagonism in schizophrenia. The differential activation of microglia cells and astrocytes may be an additional mechanism contributing to this imbalance. The immunological imbalance results both in schizophrenia and in depression in an increased Prostaglandin E(2) (PGE(2)) production and probably also in an increased Cyclo-oxygenase-2 (COX-2) expression. Although there is strong evidence for the view, that the interactions of the immune system, IDO, the serotonergic system, and the glutamatergic neurotransmission play a key role in schizophrenia and in depression, several gaps, e.g. the roles of genetics, disease course, sex, different psychopathological states, etc. have to be bridged by intense further research. There are already hints that anti-inflammatory therapy may have beneficial effects in schizophrenia and major depression. COX-2 inhibititors have been tested in animal models of depression and in preliminary clinical trials, the latter showing favourable effects compared to placebo, both, in schizophrenia and in major depression. The effects of COX-2 inhibition in the central nervous system (CNS) as well as the different components of the inflammatory system, the kynurenine-metabolism and the glutamatergic neurotransmission, however, still need careful further validation including clinical studies with sufficient sample size.

Kitzlerova E. Anders M. The role of some new factors in the pathophysiology of depression and cardiovascular disease: overview of recent research. [Review] [65 refs] Neuroendocrinology Letters. 28(6):832-40, 2007. Depressive disorders and cardiovascular disease are inter-connected by a whole range of pathophysiological mechanisms. Three biological mechanisms are fundamental: activation of the hypothalamus-hypohysis-adrenal axis with a subsequent increase in sympathetic-adrenal system activity, decrease in vagal tone with a decrease in heart rate variability, and alterations of thrombogenesis with increased platelet aggregability. Behavioural mechanisms and psycho-social factors are also integral to this common pathophysiology. Recently, research has focused mainly on studying various forms of stress, as well as changes and possibilities of influencing the autonomous vegetative system. Temporal aspects of the incidence and development of depressive episodes in relation to cardiovascular disease and subsequent cardiovascular morbidity and mortality are being studied, as well as general mortality risk factors. These findings are important for clinical practice. It is evident that in patients with untreated depressive disorder, the risk of developing cardiovascular disease is significantly higher than in patients suffering from a depressive disorder being treated with anti-depressants. From the data published so far, it may be surmised that depressive disorders in patients with cardiovascular disease may be reliably and safely treated with anti-depressants that act as inhibitors of serotonin re-uptake.

Thomas AJ. Morris C. Davis S. Jackson E. Harrison R. O'Brien JT. Soluble cell adhesion molecules in late-life depression. International Psychogeriatrics. 19(5):914-20, 2007. BACKGROUND: Late-life depression has been associated with vascular diseases and with increases in circulating cytokines and cell adhesion molecules in the prefrontal cortex. We hypothesized that soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) would be increased in late-life major depression. METHODS: Serum levels of sICAM-1 and sVCAM-1 were measured in subjects over 60 with major depression (N = 23), subsyndromal depression (N = 20) and controls (N = 25). Depression severity was assessed using the Montgomery-Asberg (MDRS) and Geriatric Depression (GDS) rating scales. RESULTS: There was no significant increase in sICAM-1 (p = 0.240) or sVCAM-1 (p = 0.600) in depression nor was there any correlation of either molecule with depression severity. Adjusting for differences in cognitive impairment did not alter these findings. There was also no difference between subjects with an early onset of depression (before 60) and those with late-onset depression. CONCLUSIONS: These findings do not provide evidence that previously reported increases in serum cytokines in depression are due to peripheral vascular disease. Although we assessed subjects for vascular diseases it is possible that subtle but important differences between groups may still have been present and may have contributed to our negative findings. Our results suggest central nervous system mechanisms, such as related to HPA axis activation, may be responsible for the enhanced inflammatory response in depression.

Vaccarino V. Johnson BD. Sheps DS. Reis SE. Kelsey SF. Bittner V. Rutledge T. Shaw LJ. Sopko G. Bairey Merz CN. National Heart, Lung, and Blood Institute. Depression, inflammation, and incident cardiovascular disease in women with suspected coronary ischemia: the National Heart, Lung, and Blood Institute-sponsored WISE study. Journal of the American College of Cardiology. 50(21):2044-50, 2007. OBJECTIVES: The purpose of this study was to examine prospectively whether inflammation explains the relationship between depression and cardiovascular disease (CVD). BACKGROUND: It is unclear whether inflammation is a mechanism linking depression to CVD. METHODS: We measured C-reactive protein (CRP) and interleukin (IL)-6 in 559 women with suspected coronary ischemia who completed the Beck Depression Inventory (BDI) at baseline and were followed over 5.9 years. We considered indicators of past and current depression to classify women into 3 groups: 1) depression, having both elevated depressive symptoms (BDI > or =10) and a previous diagnosis of depression requiring treatment; 2) possible depression, having either indicator but not both; and 3) no depression, having neither indicator of depression. The main outcome was incidence of CVD events (hospital stays for nonfatal myocardial infarction, stroke, congestive heart failure, and CVD-related mortality). RESULTS: Compared with women without depression, women with depression had a 70% higher CRP (p = 0.0008) and a 25% higher IL-6 (p = 0.04), whereas women with possible depression had 30% higher CRP (p = 0.02) and 28% higher IL-6 (p = 0.01). Depression was a significant predictor of CVD (hazard ratio 2.58, p = 0.0009), but possible depression was not (hazard ratio 1.12, p = 0.68). Adjustment for other patient factors did not substantially affect the results. Addition of CRP decreased the estimate for depression by 13% and addition of IL-6 decreased it by 4%. Both depression and inflammatory biomarkers remained independent predictors of outcome. CONCLUSIONS: Despite their robust association with depression, inflammatory biomarkers explain only a small portion of the association between depression and CVD incidence.

Szelenyi J. Vizi ES. The catecholamine cytokine balance: interaction between the brain and the immune system. [Review] [65 refs] Annals of the New York Academy of Sciences. 1113:311-24, 2007. Cytokines are involved both in various immune reactions and in controlling certain events in the central nervous system (CNS). In our earlier studies, it was shown that monoamine neurotransmitters, released in stress situations, represent a tonic sympathetic control on cytokine production and on the balance of proinflammatory/anti-inflammatory cytokines. Basic and clinical studies have provided evidence that the biophase level of monoamines, determined by the balance of their release and uptake, is involved in the pathophysiology and treatment of depression, while inflammatory mediators might also have a role in its etiology. In this work, we studied the role of changes in norepinephrine (NE) level on the lipopolysaccharide (LPS) evoked tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 response both in the plasma and in the hippocampus of mice. We demonstrated that the LPS induced TNF-alpha response is in direct correlation with the biophase level of NE, as it is significantly higher when the release of NE of vesicular origin was completely inhibited in an animal model of depression (reserpine treatment) and it is significantly lower in the case of increasing biophase levels of NE by genetic (NET-KO) or chemical (desipramine) disruption of NE reuptake. IL-10 was changed inversely to TNF-alpha levels only in the desipramine-treated animals. Our results showed that depression is related both to changes in peripheral and in hippocampal inflammatory cytokine production and to monoamine neurotransmitter levels. Since several anti-inflammatory drugs also have antidepressant effects, we hypothesized that antidepressants are also able to modulate the LPS-induced inflammatory response, which might contribute to their antidepressant effect.

Rosenkranz MA. Substance P at the nexus of mind and body in chronic inflammation and affective disorders. [Review] [477 refs] Psychological Bulletin. 133(6):1007-37, 2007. For decades, research has demonstrated that chronic diseases characterized by dysregulation of inflammation are particularly susceptible to exacerbation by stress and emotion. Likewise, rates of depression and anxiety are overrepresented in individuals suffering from chronic inflammatory disease. In recent years, substance P has been implicated in both the pathophysiology of inflammatory disease and the pathophysiology of depression and anxiety by 2 parallel fields of study. This review integrates the literature from these 2 parallel fields and examines the possibility that substance P dysregulation may be a point of convergence underlying the overlap of chronic inflammatory disease and mood and anxiety disorders. First, the involvement of substance P in peripheral inflammation and in the immune events associated with chronic inflammatory disease is discussed, with a focus on inflammatory bowel disease and asthma. Next, the function of substance P in the communication of peripheral inflammation to the brain is considered. Finally, to complete the bidirectional loop of brain-immune interactions, substance P expression in anxiety and depression as well as its potential role in the neural regulation of peripheral inflammation is reviewed.

Arbelaez JJ. Ariyo AA. Crum RM. Fried LP. Ford DE. Depressive symptoms, inflammation, and ischemic stroke in older adults: a prospective analysis in the cardiovascular health study. Journal of the American Geriatrics Society. 55(11):1825-30, 2007. OBJECTIVES: To investigate the mediator role of inflammation in any relationship between depressive symptoms and ischemic stroke. DESIGN: Longitudinal prospective study. SETTING: Review of medical records, death certificates, and the Medicare healthcare utilization database for hospitalizations. PARTICIPANTS: Total of 5,525 elderly men and women aged 65 and older who were prospectively followed from 1989 to 2000 as participants in the Cardiovascular Health Study. MEASUREMENTS: Depression symptom scores, inflammatory markers. RESULTS: Greater depressive symptoms were associated with risk of ischemic stroke (unadjusted hazard ratio (HR)=1.32, 95% confidence interval (CI)=1.09-1.59; HR=1.26, 95% CI=1.03-1.54, adjusted for traditional risk factors). When a term for inflammation (C-reactive protein (CRP)) was introduced in the model, the HRs were not appreciably altered (unadjusted HR=1.31, 95% CI=1.08-1.58; adjusted HR=1.25, 95% CI=1.02-1.53), indicating that CRP at baseline was not a mediator in this relationship. In analyses stratified according to CRP levels, a J-shaped relationship between depressive symptoms and stroke was evident in the unadjusted analyses; in the fully adjusted model, only CRP in the highest tertile was associated with a higher risk for stroke in the presence of higher depressive symptoms scores. CONCLUSION: The analyses from this prospective study provide evidence of a positive association between depressive symptoms and risk of incident stroke. Inflammation, as measured according to CRP at baseline, did not appear to mediate the relationship between depressive symptoms and stroke.

Bilgic A. Akgul A. Sezer S. Arat Z. Ozdemir FN. Haberal M. Nutritional status and depression, sleep disorder, and quality of life in hemodialysis patients. Journal of Renal Nutrition. 17(6):381-8, 2007. OBJECTIVE: The malnutrition-inflammation score (MIS) is a scoring system that measures malnutrition and inflammation. We sought to explore its associations with depression, sleep disturbance, and quality of life. DESIGN: This was a cross-sectional study. SETTING: This study took place at the Baskent University Outpatient Hemodialysis Unit (Ankara, Turkey). PATIENTS: We enrolled 67 hemodialysis patients (male/female, 34/33; age, 47.7 +/- 11.4 years [mean +/- SD]; hemodialysis duration, 103.7 +/- 59.1 months [mean +/- SD]). INTERVENTION: We retrospectively recorded patients' monthly clinical and laboratory findings from the previous 6 months. The same physician calculated MIS scores. We interviewed all patients, and each completed a Beck Depression Inventory (BDI) assessment. We used the Pittsburgh Sleep Quality Index (PSQI) to assess quality of sleep, and the Medical Outcomes Study 36-item short form (SF-36) questionnaire to evaluate health-related quality of life. MAIN OUTCOME MEASURES: The main outcome measures involved the univariate and multivariate relationships of the MIS with BDI, PSQI, and SF-36. RESULTS: Patients with PSQI scores of < or = 5 ("good sleepers") had lower MIS scores than did poor sleepers (6.8 +/- 2.5 vs. 8.8 +/- 3.2, P < .05). Patients with moderate-to-severe depression (BDI score > or = 19) had higher MIS scores (9.0 +/- 3.2 vs. 6.5 +/- 2.5, P = .005) and higher PSQI scores (7.6 +/- 2.1 vs. 4.7 +/- 1.8, P = .001), compared with patients with BDI scores < 19. Increased MIS scores were correlated with increased comorbidity (P = .01) and poor SF-36 scores (P = .009). CONCLUSION: Increased MIS is significantly associated with the presence of depression, sleep disorders, and poor quality of life. This close relationship may help establish the MIS as an important determinant of the increased morbidity and mortality of hemodialysis patients.

Leonard BE. Inflammation, depression and dementia: are they connected?. [Review] [82 refs] Neurochemical Research. 32(10):1749-56, 2007. Chronic inflammation is now considered to be central to the pathogenesis not only of such medical disorders as cardiovascular disease, multiple sclerosis, diabetes and cancer but also of major depression. If chronic inflammatory changes are a common feature of depression, this could predispose depressed patients to neurodegenerative changes in later life. Indeed there is now clinical evidence that depression is a common antecedent of Alzheimer's disease and may be an early manifestation of dementia before the cognitive declines becomes apparent. This review summarises the evidence that links chronic low grade inflammation with changes in brain structure that could precipitate neurodegenerative changes associated with Alzheimer's disease and other dementias. For example, neuronal loss is a common feature of major depression and dementia. It is hypothesised that the progress from depression to dementia could result from the activation of macrophages in the blood, and microglia in the brain, that release pro-inflammatory cytokines. Such cytokines stimulate a cascade of inflammatory changes (such as an increase in prostaglandin E2, nitric oxide in addition to more pro-inflammatory cytokines) and a hypersecretion of cortisol. The latter steroid inhibits protein synthesis thereby reducing the synthesis of neurotrophic factors and preventing reairto damages neuronal networks. In addition, neurotoxic end products of the tryptophan-kynurenine pathway, such as quinolinic acid, accumulate in astrocytes and neurons in both depression and dementia. Thus increased neurodegeneration, reduced neuroprotection and neuronal repair are common pathological features of major depression and dementia. Such changes may help to explain why major depression is a frequent prelude to dementia in later life.

Ranjit N. Diez-Roux AV. Shea S. Cushman M. Seeman T. Jackson SA. Ni H. Psychosocial factors and inflammation in the multi-ethnic study of atherosclerosis. Archives of Internal Medicine. 167(2):174-81, 2007. BACKGROUND: Psychosocial factors are associated with the development and progress of cardiovascular disease, but the pathological mechanisms remain unclear. We examined the associations of psychosocial risk factors for cardiovascular disease with concentrations of inflammatory markers among healthy adults and assessed the extent to which these associations are mediated by behaviors, body mass index (BMI), and diabetes mellitus. METHODS: This cross-sectional study used data from the baseline examination of the Multi-Ethnic Study of Atherosclerosis, a multisite study of 6814 men and women aged 45 to 84 years. Regression analyses were used to estimate associations of cynical distrust, chronic stress, and depression with serum levels of C-reactive protein, IL-6, and fibrinogen before and after adjustment for socioeconomic position, behaviors, BMI, and diabetes. RESULTS: Higher levels of cynical distrust were associated with higher levels of inflammatory markers. The percentage differences (95% confidence intervals [CIs]) comparing the 80th and 20th percentiles of the scale were 7% (3%-11%) for IL-6; 9% (2%-16%) for C-reactive protein; and 1.3% (0.1%-2.4%) for fibrinogen. Higher levels of chronic stress were associated with higher concentrations of IL-6 and C-reactive protein. The percentage differences (95% CIs) comparing 2 and 0 ongoing stressful circumstances were 4% (1%-8%) for IL-6 and 5% (1%-11%) for C-reactive protein. Depression was positively associated with the level of IL-6 (percentage difference [95% CI] comparing the Center for Epidemiologic Studies-Depression Scale scores of >or=21 vs <21 was 7% [1%-14%]). Associations of psychosocial factors with inflammatory markers were reduced by 20% to 55% after adjustment for behavioral factors and by 45% to 100% after adjustment for BMI and diabetes, mostly owing to the effect of BMI. No associations remained after controlling for socioeconomic position, behaviors, BMI, and diabetes. CONCLUSIONS: Psychosocial factors are associated with higher levels of inflammatory markers, most consistently for cynical distrust. Results are compatible with a mediating role of BMI, behaviors, and diabetes.

Pavlov VA. Tracey KJ. Controlling inflammation: the cholinergic anti-inflammatory pathway. Biochemical Society Transactions. 34(Pt 6):1037-40, 2006. Innate immune responses and inflammation are regulated in part by neural mechanisms. In the present paper, we summarize experimental evidence that reveals that innate immunity and inflammation are controlled by the vagus nerve, previously known as a regulator of other vital physiological functions. Activation of vagus nerve cholinergic signalling inhibits TNF (tumour necrosis factor) and other pro-inflammatory cytokine overproduction through 'immune' alpha7 nicotinic receptor-mediated mechanisms. This efferent vagus nerve-based 'cholinergic anti-inflammatory pathway' has been elucidated as a critical regulator of inflammation in several experimental models of diseases. Our recent observations have shown that activation of central (brain) cholinergic transmission by selective muscarinic receptor ligands results in lower systemic TNF levels in rodents and indicate that the efferent vagus nerve may provide a functional brain-to-immune connection. Thus central cholinergic signalling is implicated in the activation of the cholinergic anti-inflammatory pathway. Electrical vagus nerve stimulation is clinically approved for the treatment of epilepsy and depression and current knowledge suggests that it could be utilized to control inflammation. Advances in understanding the receptor and molecular mechanisms of cholinergic anti-inflammatory signalling indicate that selective alpha7 nicotinic receptor agonists and centrally acting cholinergic enhancers can be used in the treatment of pathological conditions characterized by cytokine overproduction.

Leonard BE. Myint A. Inflammation and depression: is there a causal connection with dementia?. [Review] [124 refs] Neurotoxicity Research. 10(2):149-60, 2006. 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.

Godbout JP. Johnson RW. Age and neuroinflammation: a lifetime of psychoneuroimmune consequences. [Review] [119 refs] Neurologic Clinics. 24(3):521-38, 2006. This article reviews the literature indicating that the innate immune cells of the brain become more reactive with age. Although it is unclear how glia reactivity increases, emerging evidence suggests these alterations allow exacerbated neuroinflammation and sickness behavior following peripheral immune activation. This amplified or prolonged exposure to inflammatory cytokines in the brain may impair neuronal plasticity and underlie a heightened neuroinflammatory response in the aged that also may lead to other neurobehavioral impairments such as delirium, depression, and, potentially, the onset of neurologic disease. Therefore pharmacologic strategies to decrease neuroinflammation associated with infection may be important for improving recovery from sickness and reducing neurobehavioral deficits in the elderly.

Muller N. Schwarz MJ. Dehning S. Douhe A. Cerovecki A. Goldstein-Muller B. Spellmann I. Hetzel G. Maino K. Kleindienst N. Moller HJ. Arolt V. Riedel M. 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. Molecular Psychiatry. 11(7):680-4, 2006. 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.

McCaffery JM. Frasure-Smith N. Dube MP. Theroux P. Rouleau GA. Duan Q. Lesperance F. Common genetic vulnerability to depressive symptoms and coronary artery disease: a review and development of candidate genes related to inflammation and serotonin. [see comment]. [Review] [233 refs] Psychosomatic Medicine. 68(2):187-200, 2006. OBJECTIVE: Although it is well established that depressive symptoms are associated with recurrent cardiac events among cardiac patients and novel cardiac events among participants with no known coronary artery disease (CAD), the nature of this association remains unclear. In this regard, little attention has been paid to the possibility that common genetic vulnerability contributes to both depressive symptoms and CAD. In this paper, we review the existing evidence for common genetic contributions to depression and CAD, primarily using evidence from twin and family studies, followed by a review of two major pathophysiological mechanisms thought to underlie covariation between depressive symptoms and CAD: inflammation and serotonin. We conclude with an overview of select candidate genes within these pathways. METHODS: Literature review. RESULTS: In twin studies, both depression and CAD appear heritable. In the only twin study to consider depression and CAD jointly, the correlation across heritabilities was 0.42, suggesting that nearly 20% of variability in depressive symptoms and CAD was attributable to common genetic factors. In addition, although it is plausible that genetic variation related to inflammation and serotonin may be associated with both depression and CAD, genetic variation related to inflammation has been primary examined in relation to CAD, whereas genetic variation in the serotonin system has been primarily examined in relation to depression. CONCLUSIONS: It appears that the covariation of depressive symptoms and CAD may be attributable, in part, to a common genetic vulnerability. Although several pathways may be involved, genes within the inflammation and serotonin pathways may serve as good candidates for the first steps in identifying genetic variation important for depression, CAD or both.

Raison CL. Capuron L. Miller AH. Cytokines sing the blues: inflammation and the pathogenesis of depression. [Review] [91 refs] Trends in Immunology. 27(1):24-31, 2006. 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.