Further evidence for the depressive effects of cytokines: anhedonia and neurochemical changes

Efficacy and safety of celecoxib monotherapy for treatment of moderate depressive symptoms following COVID-19 infection: A randomized, double-blind, placebo-controlled trial

OBJECTIVE

Celecoxib, a nonsteroidal anti-inflammatory agent, was found to be an effective add-on treatment for unipolar and bipolar depression. We investigated the potential beneficial effect of celecoxib monotherapy on depressive symptoms after Coronavirus disease (COVID-19).

METHODS

This was a randomized, double-blind, placebo-controlled clinical trial investigating the therapeutic effects of celecoxib monotherapy in patients with moderate depressive symptoms following COVID-19 infection. Patients were randomized to receive either a celecoxib capsule (100 mg) twice daily or a placebo capsule twice daily for 6 weeks. Participants were assessed with the Hamilton Depression Rating Scale (HDRS) and the side effect checklist at baseline and weeks 3 and 6.

RESULTS

A total of 62 patients were included. GLM repeated-measures showed a significant effect of time × treatment (F = 12.95, df = 1.98, p < 0.001) for celecoxib, suggesting superior improvement of depressive symptoms in celecoxib compared to placebo from baseline to the study endpoint. HDRS scores in the celecoxib group showed a greater decline from baseline to both week 3 (t = 4.12, p < 0.001, Cohen's d = 1.10) and week 6 (t = 4.76, p < 0.001, Cohen's d = 1.27), compared to the placebo group. Rate of response to treatment (70% vs 9%, p < 0.001) and remission (67% vs 0%, p < 0.001) was significantly higher in celecoxib compared to the placebo group at week 6. Adverse event frequencies were not significantly different between the two groups.

CONCLUSION

We demonstrated that treatment with celecoxib significantly improved depression scores of patients with depressive symptoms following COVID-19 infection. Further trials with larger sample sizes and longer study periods should assess our findings before any suggestion for clinical use. The trial was prospectively registered at the Iranian registry of clinical trials (www.irct.ir; registration number: IRCT20090117001556N142).

The social environment alters neural responses to a lipopolysaccharide challenge

Sick animals display drastic changes in their behavioral patterns, including decreased activity, decreased food and water intake, and decreased interest in social interactions. These behaviors, collectively called "sickness behaviors", can be socially modulated. For example, when provided with mating opportunities, males of several species show reduced sickness behaviors. While the behavior is known to change, how the social environment affects neural molecular responses to sickness is not known. Here, we used a species, the zebra finch, Taeniopygia guttata, where males have been shown to decrease sickness behaviors when presented with novel females. Using this paradigm, we obtained samples from three brain regions (the hypothalamus, the bed nucleus of the stria terminalis, and the nucleus taeniae) from lipopolysaccharide (LPS) or control treated males housed under four different social environments. Manipulation of the social environment rapidly changed the strength and co-expression patterns of the neural molecular responses to the immune challenge in all brain regions tested, therefore suggesting that the social environment plays a significant role in determining the neural responses to an infection. In particular, brains of males paired with a novel female showed muted immune responses to LPS, as well as altered synaptic signaling. Neural metabolic activity in response to the LPS challenge was also affected by the social environment. Our results provide new insights into the effects of the social environment on brain responses to an infection, thereby improving our understanding of how the social environment can affect health.

Using Precision Medicine with a Neurodevelopmental Perspective to Study Inflammation and Depression

PURPOSE OF REVIEW

To consider various precision medicine approaches to further elucidate the relationship between inflammation and depression and to illustrate how a neurodevelopmental perspective can help in this regard.

RECENT FINDINGS

Inflammation associates most strongly with phenotypes of depression that reflect illness behavior and/or metabolic dysfunction and obesity. A separate body of research has shown that maternal inflammation during pregnancy can alter brain circuitry important for mood regulation and/or reward in the developing fetus. Our research group is finding that maternal CRP levels differentially predict positive and negative affect in children assessed at age 4 years, depending on the timing of plasma sampling during pregnancy and the sex of the child. Recent authors have stressed the need to use a variety of precision medicine approaches to refine our understanding of inflammation-depression links. Adding a neurodevelopmental perspective may help to address some of the methodological challenges in this active area of study.

Gastrointestinal (non-systemic) antibiotic rifaximin differentially affects chronic stress-induced changes in colon microbiome and gut permeability without effect on behavior

Chronic stress is often accompanied by gastrointestinal symptoms, which might be due to stress-induced shift of gut microbiome to pathogenic bacteria. It has been hypothesized that stress alters gut permeability and results in mild endotoxemia which exaggerates HPA activity and contributes to anxiety and depression. To reveal the relationship between microbiome composition, stress-induced gastrointestinal functions and behavior, we treated chronically stressed mice with non-absorbable antibiotic, rifaximin. The "two hits" stress paradigm was used, where newborn mice were separated from their mothers for 3 h daily as early life adversity (maternal separation, MS) and exposed to 4 weeks chronic variable stress (CVS) as adults. 16S rRNA based analysis of gut microbiome revealed increases of Bacteroidetes and Proteobacteria and more specifically, Clostridium species in chronically stressed animals. In mice exposed to MS + CVS, we found extenuation of colonic mucosa, increased bacterial translocation to mesenteric lymph node, elevation of plasma LPS levels and infiltration of F4/80 positive macrophages into the colon lamina propria. Chronically stressed mice displayed behavioral signs of anxiety-like behavior and neophobia. Rifaximin treatment decreased Clostridium concentration, gut permeability and LPS plasma concentration and increased colonic expression of tight junction proteins (TJP1, TJP2) and occludin. However, these beneficial effects of rifaximin in chronically stressed mice was not accompanied by positive changes in behavior. Our results suggest that non-absorbable antibiotic treatment alleviates stress-induced local pathologies, however, does not affect stress-induced behavior.

Effects of stress-induced inflammation on reward processing in healthy young women

BACKGROUND

Anhedonia, or loss of interest or pleasure, is a feature of depression and transdiagnostic construct in psychopathology. Theory and compelling evidence from preclinical models implicates stress-induced inflammation as a psychobiological pathway to anhedonic behavior; however, this pathway has not been tested in human models. Further, although anhedonia may reflect dysregulation in multiple dimensions of reward, the extent to which stress-induced inflammation alters these dimensions is unclear. Thus, the current experimental study used a standardized laboratory stressor task to elicit an inflammatory response and evaluate effects of stress-induced inflammation on multiple behavioral indices of reward processing.

METHODS

Healthy young women (age 18-25) completed behavioral reward tasks assessing reward learning, motivation, and sensitivity and were randomized to undergo an acute psychosocial stressor (n = 37) or a no-stress active control (n = 17). Tasks were re-administered 90-120 min post-stress to coincide with the peak of the stress-induced inflammatory response. Blood samples were collected for assessment of the pro-inflammatory cytokine interleukin-6 (IL-6) at baseline and 90 and 120 min post stressor.

RESULTS

Stress-induced IL-6 was associated with increased response bias during reward learning and increased motivation when probability of receiving a reward was low. Sensitivity to reward in the context of a motivation task was not altered in association with stress-induced IL-6.

CONCLUSIONS

Contrary to hypotheses, mild increases in IL-6 following acute stress were associated with increased reward responsiveness during reward learning and selective increases in motivation. Results contribute to an emerging and nuanced literature linking inflammation to reward processing, and demonstrate that behavioral effects of stress-induced inflammation may be detected in the laboratory setting.

CLINICAL TRIAL REGISTRATION

NCT03828604.

Therapeutic Potential of Hericium erinaceus for Depressive Disorder

Depression is a common and severe neuropsychiatric disorder that is one of the leading causes of global disease burden. Although various anti-depressants are currently available, their efficacies are barely adequate and many have side effects. Hericium erinaceus, also known as Lion’s mane mushroom, has been shown to have various health benefits, including antioxidative, antidiabetic, anticancer, anti-inflammatory, antimicrobial, antihyperglycemic, and hypolipidemic effects. It has been used to treat cognitive impairment, Parkinson’s disease, and Alzheimer’s disease. Bioactive compounds extracted from the mycelia and fruiting bodies of H. erinaceus have been found to promote the expression of neurotrophic factors that are associated with cell proliferation such as nerve growth factors. Although antidepressant effects of H. erinaceus have not been validated and compared to the conventional antidepressants, based on the neurotrophic and neurogenic pathophysiology of depression, H. erinaceus may be a potential alternative medicine for the treatment of depression. This article critically reviews the current literature on the potential benefits of H. erinaceus as a treatment for depressive disorder as well as its mechanisms underlying the antidepressant-like activities.

Expression of inflammatory markers in women with perinatal depressive symptoms

Perinatal depression affects 10-20% of women and is associated with poor outcomes for mother and child. Inflammation is associated with depression in non-pregnant adults. Perinatal depression and inflammation in pregnancy are independently associated with morbidities including obesity, gestational diabetes, preeclampsia, and preterm birth. The role of inflammation in perinatal depression has received little attention. We hypothesized an association between self-reported perinatal depressive symptoms and serum inflammatory biomarkers TNF-α, IL-6, IL-1β, and CRP. 110 healthy gravidas were recruited in third trimester from an academic medical center, with a baseline study visit at a mean of 32.5 (SD ± 1.8) weeks gestational age. Sixty-three participants completed the Edinburgh Postnatal Depression Scale (EPDS) and provided demographic information and serum samples upon enrollment and at 3 and 6 months postpartum. Serum inflammatory markers were quantified by multiplex array. Multiple linear mixed effects models were used to evaluate trends of biomarkers with the EPDS score in the third trimester of pregnancy and the postpartum period. Elevated serum TNF-α was associated with lower EPDS total score (β = - 0.90, p = 0.046) after adjusting for demographics and medication use. In contrast, IL-6, CRP, and IL-1β did not demonstrate statistically significant associations with depressive symptoms by the EPDS in either crude or adjusted models. Study findings showed no association or an inverse (TNF-α) association between inflammatory markers and perinatal depressive symptoms. Relevant literature evaluating a role for inflammation in depression in the unique context of pregnancy is both limited and inconsistent, and further exploration is merited.

Behavioural medicine and gastrointestinal disorders: the promise of positive psychology

Psychosocial risk factors linked to brain-gut dysregulation are prevalent across the spectrum of gastrointestinal disorders and are associated with poor patient outcomes. Robust and reproducible data in the areas of behavioural intervention science and the brain-gut axis have led to major advances in patient care, including the routine use of brain-gut psychotherapies to manage digestive symptoms and optimize coping. The logical next step for the emerging field of psychogastroenterology is to develop a scientific framework that enables the identification of those individual characteristics and coping styles that buffer patients against the negative psychological effects of chronic gastrointestinal disorders. A shift towards a strength-based, positive psychological science of gastrointestinal disorders could facilitate the integration of early, effective psychological care into gastroenterology practice. In this Perspective, I discuss the potential role of three human strengths with relevance to gastrointestinal health - resilience, optimism and self-regulation - and how these three constructs can be cultivated through existing or emerging brain-gut psychotherapies.

Stress, anxiety, and depression of both partners in infertile couples are associated with cytokine levels and adverse IVF outcome

PROBLEM

Psychiatric disorders and stress in women have been associated with poor IVF outcome. We hypothesized that both partners in the infertile couples are emotionally affected, and cytokines in both may link psychological to reproductive outcome.

METHOD OF STUDY

Forty-five IVF couples completed questionnaires and visual analog scales for stress and psychiatric disorders and had cytokines measured in serum, semen, cervicovaginal, and follicular fluids. Multivariable analyses, t tests, maximum likelihood estimates, Spearman correlation, and data mining were applied.

RESULTS

Psychopathology was found in 72% of the couples. Female and male stress were associated with stress, anxiety, and depression in the respective partner, and with a lower likelihood of clinical pregnancy and live birth. Lower serum TGF-β and higher cervicovaginal IL-6 and IL-1β were associated with stress. In data decision trees, cytokines in relation to stress and depression in both partners were found indicative of IVF failure.

CONCLUSION

Infertile couples may benefit from psychiatric evaluation and treatment of both partners.

Distinct inflammatory response patterns are evident among men and women with higher depressive symptoms

Extensive research links depression and inflammation, with emerging evidence suggesting some differences between males and females in these associations. However, relatively few studies have examined stimulated inflammatory responses (ex vivo) in depression. The present research investigated the associations between depressive symptoms, basal inflammation, and LPS-stimulated production of pro- (IL-1β, IL-6, IL-8, TNF-α) and an anti-inflammatory cytokine (IL-10), with a focus on the extent to which gender moderates these relationships. As part of a larger study, 162 socio-economically and racially diverse subjects (ages 25-65, 67% women) completed extensive self-report measures, including depressive symptoms. Whole blood was quantified for basal inflammation, or incubated with 1μg/mL lipopolysaccharide (LPS) for 2h (at 37°C, 5% CO2) to quantify inflammatory responses to bacterial challenge. We examined the associations between depression and inflammatory markers in regression analyses, controlling for age, BMI, race/ethnicity, income, education, and use of medications. No main effects were observed between depressive symptoms and basal or stimulated levels of inflammation. Moderation analyses revealed a significant interaction between depressive symptoms and gender for stimulated TNF-α, stimulated IL-6 (p<0.05), and a marginally significant interaction for stimulated IL-10 (p=0.07). For men, higher depressive symptoms were associated with significantly higher production of TNF-α (p<0.05) and marginally higher IL-6 (p=0.07), but not with the anti-inflammatory cytokine IL-10. For women, higher depressive symptoms were associated with significantly lower production of TNF-α and IL-10 (ps<0.05), and marginally lower IL-6 (p=0.06). These findings provide evidence for gender differences in the association of depressive symptoms with inflammatory response patterns, and highlight the utility of assessing ex vivo immune responses in blood. Implications for health are discussed.

Interactions between pro-inflammatory cytokines and statins on depression in patients with acute coronary syndrome

OBJECTIVE

Pro-inflammatory cytokines are associated with the development of depression and statins exert anti-inflammatory and antidepressant effects. The present study aimed to investigate associations between interleukin (IL)-6 and IL-18 and depression in patients with acute coronary syndrome (ACS) and potential interactions between statin use and pro-inflammatory cytokines on depression in this population.

METHODS

We used pooled datasets from 1-year follow-up data from a 24-week randomized double-blind placebo-controlled trial (RCT) of escitalopram for treatment of depressive disorder and data from a naturalistic, prospective, observational cohort study in patients with ACS. IL-6 and IL-18 levels were measured at baseline. Logistic regression models were used to investigate independent associations of IL-6/IL-18 levels with depressive disorder at baseline and at 1year. We repeated all analyses by reference to statin use to determine whether any significant association emerged.

RESULTS

Of the 969 participants, 378 (39.0%) had major or minor depression at baseline. Of 711 patients followed-up at 1year, 183 (25.7%) had depression. Logistic regression analysis showed that higher IL-6 and IL-18 levels at baseline were significantly associated with baseline depression after adjusting for other variables (adjusted p-values=0.005 and 0.001, respectively). IL-6 and IL-18 levels were also significantly higher in patients with depression at the 1-year follow-up after adjusting for other variables amongst those not taking statins (adjusted p-values=0.040 and 0.004, respectively); but this was not the case in patients taking statins.

CONCLUSION

Levels of pro-inflammatory cytokines appear to predict development of depression after ACS and statins attenuate the effects of cytokines on depression.

A Randomized Controlled Trial of the Effects of Mindfulness-Based Stress Reduction (MBSR[BC]) on Levels of Inflammatory Biomarkers Among Recovering Breast Cancer Survivors

PURPOSE

The purpose of this substudy of a large randomized controlled trial was to evaluate the efficacy of the Mindfulness-Based Stress Reduction (Breast Cancer) (MBSR[BC]) program compared to usual care (UC) in normalizing blood levels of pro-inflammatory cytokines among breast cancer survivors (BCS).

METHOD

A total of 322 BCS were randomized to either a 6-week MBSR(BC) program or a UC. At baseline and 6 and 12 weeks, 10 ml of venous blood and demographic and clinical data were collected and/or updated. Plasma cytokines (interleukin [IL]-1β, IL-6, IL-10, tumor necrosis factor [TNF] α, transforming growth factor [TGF] β1, soluble tumor necrosis factor receptor [sTNFR] 1) were assayed. Linear mixed models were used to assess cytokine levels across three time points (baseline and 6 and 12 weeks) by group (MBSR[BC] vs. UC).

RESULTS

Of the six measured cytokines, three were nondetectable at rates greater than 50% (IL-10, IL-1β, TGF-β1) and, because of overall low prevalence, were not analyzed further. For the remaining cytokines (TNFα, IL-6, sTNFR1), results showed that TNFα and IL-6 increased during the follow-up period (between 6 and 12 weeks) rather than during the MBSR(BC) training period (between baseline and 6 weeks), while sTNFR1 levels did not change significantly across the 12-week period.

CONCLUSIONS

Study results suggest that MBSR(BC) affects cytokine levels in BCS, mainly with increases in TNFα and IL-6. The data further suggest that B-cell modulation may be a part of immune recovery during breast cancer management and that increases in TNFα and IL-6 may be markers for MBSR(BC)-related recovery.

(Putative) sex differences in neuroimmune modulation of memory

The neuroimmune system is significantly sexually dimorphic, with sex differences evident in the number and activation states of microglia, in the activation of astrocytes, and in cytokine release and function. Neuroimmune cells and signaling are now recognized as critical for many neural functions throughout the life span, including synaptic plasticity and memory function. Here we address the question of how cytokines, astrocytes, and microglia contribute to memory, and specifically how neuroimmune modulation of memory differentially affects males and females. Understanding sex differences in both normal memory processes and dysregulation of memory in psychiatric and neurological disorders is critical for developing treatment and preventive strategies for memory disorders that are effective for both men and women. © 2016 Wiley Periodicals, Inc.

Effects of interleukin-6, interleukin-18, and statin use, evaluated at acute stroke, on post-stroke depression during 1-year follow-up

Proinflammatory cytokines are associated with the development of post-stroke depression (PSD). Statins are thought to possess anti-inflammatory properties but their interactions with cytokines regarding the risk of PSD have yet to be investigated. Thus, the present study aimed to determine whether interleukin (IL)-6 and IL-18 were associated with the development of depression at 2 weeks and 1year after stroke using a longitudinal post-stroke cohort. Furthermore, this study examined the potential interactions between statin use and cytokines on PSD. For this study, 286 patients were evaluated 2 weeks after stroke and 222 patients were followed-up 1year later. Depression was diagnosed using criteria from the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) and then categorized into no PSD or any PSD, which included diagnoses of both major and minor depression. The effects of IL-6 and IL-18 on PSD as well as their interaction with a statin at both examination time-points were investigated using a multivariate logistic regression model. Higher IL-6 and IL-18 levels were independently associated with depressive disorders within 2 weeks and at 1year after stroke. When stratified by statin use, these significant associations were more evident in patients who did not use a statin. Furthermore, there was a significant interaction between statin use and IL-6 on the presence of a depressive disorder at 1year. The present findings support the cytokine hypothesis of PSD and indicate that the preventive effects of statin use against PSD may be mediated by its interactions with IL-6.

Reelin-Related Disturbances in Depression: Implications for Translational Studies

The finding that reelin expression is significantly decreased in mood and psychotic disorders, together with evidence that reelin can regulate key aspects of hippocampal plasticity in the adult brain, brought our research group and others to study the possible role of reelin in the pathogenesis of depression. This review describes recent progress on this topic using an animal model of depression that makes use of repeated corticosterone (CORT) injections. This methodology produces depression-like symptoms in both rats and mice that are reversed by antidepressant treatment. We have reported that CORT causes a decrease in the number of reelin-immunopositive cells in the dentate gyrus subgranular zone (SGZ), where adult hippocampal neurogenesis takes place; that down-regulation of the number of reelin-positive cells closely parallels the development of a depression-like phenotype during repeated CORT treatment; that reelin downregulation alters the co-expression of reelin with neuronal nitric oxide synthase (nNOS); that deficits in reelin might also create imbalances in glutamatergic and GABAergic circuits within the hippocampus and other limbic structures; and that co-treatment with antidepressant drugs prevents both reelin deficits and the development of a depression-like phenotype. We also observed alterations in the pattern of membrane protein clustering in peripheral lymphocytes in animals with low levels of reelin. Importantly, we found parallel changes in membrane protein clustering in depression patients, which differentiated two subpopulations of naïve depression patients that showed a different therapeutic response to antidepressant treatment. Here, we review these findings and develop the hypothesis that restoring reelin-related function could represent a novel approach for antidepressant therapies.

Mapping inflammation onto mood: Inflammatory mediators of anhedonia

Evidence supports inflammatory involvement in mood and cognitive symptoms across psychiatric, neurological and medical disorders; however, inflammation is not a sensitive or specific characteristic of these diagnoses. The National Institute of Mental Health Research Domain Criteria (RDoC) ask for a shift away from symptom-based diagnoses toward a transdiagnostic neurobiological focus in the study of brain illnesses. The RDoC matrix may provide a useful framework for integrating the effects of inflammation on brain function. Based on preclinical and clinical findings, relevant relationships span negative and positive valence systems, cognitive systems, systems for social processes and arousal/regulatory systems. As an exemplar, we consider the psychopathological domain of anhedonia, conceptualizing the relevance of inflammation (e.g., cellular immunity) and downstream processes (e.g., indoleamine 2,3-dioxygenase activation and oxidative inactivation of tetrahydrobiopterin) across RDoC units of analysis (e.g., catecholamine neurotransmitter molecules, nucleus accumbens medium spiny neuronal cells, dopaminergic mesolimbic and mesocortical reward circuits, animal paradigms, etc.). We discuss implications across illnesses affecting the brain, including infection, major depressive disorder, stroke, Alzheimer's disease and type 2 diabetes.

Serotonin transporter clustering in blood lymphocytes predicts the outcome on anhedonia scores in naïve depressive patients treated with antidepressant medication

BACKGROUND

We have shown that serotonin transporter (SERT) clustering in blood lymphocytes is altered in major depression and correlates with pharmacological therapeutic responses measured with the Hamilton scale. In the present report, we extend these results to the self-assessment anhedonia scale, as anhedonia is a cardinal symptom of major depression that is difficult to treat with first-line antidepressants.

METHODS

We collected blood samples from 38 untreated depression patients at the time of enrolment and 8 weeks after pharmacological treatment. We used the self-assessment anhedonia scale to evaluate anhedonia symptoms before and after treatment. We also used quantitative immunocytochemistry to measure SERT clusters in blood lymphocytes.

RESULTS

Evaluation of the distribution of SERT clusters size in the plasma membrane of lymphocytes identified two subpopulations of naive depression patients: Depression I (D-I) and Depression II (D-II). While naïve D-I and D-II patients initially showed similar anhedonia scores, D-II patients showed a good response in anhedonia symptoms after 8 weeks of psychopharmacological treatment, whereas D-I patients failed to show any improvement. Psychopharmacological treatment also induced an increase in the number of SERT clusters in lymphocytes in the D-II group, and this increase correlated with the improvement in anhedonia symptoms.

CONCLUSIONS

SERT clustering in peripheral lymphocytes can be used to identify patient response to antidepressant therapy as ascertained by anhedonia scores.

Peripheral and Central Mechanisms of Stress Resilience

Viable new treatments for depression and anxiety have been slow to emerge, likely owing to the complex and incompletely understood etiology of these disorders. A budding area of research with great therapeutic promise involves the study of resilience, the adaptive maintenance of normal physiology and behavior despite exposure to marked psychological stress. This phenomenon, documented in both humans and animal models, involves coordinated biological mechanisms in numerous bodily systems, both peripheral and central. In this review, we provide an overview of resilience mechanisms throughout the body, discussing current research in animal models investigating the roles of the neuroendocrine, immune, and central nervous systems in behavioral resilience to stress.

Neuropathic pain-induced depressive-like behavior and hippocampal neurogenesis and plasticity are dependent on TNFR1 signaling

Patients suffering from neuropathic pain have a higher incidence of mood disorders such as depression. Increased expression of tumor necrosis factor (TNF) has been reported in neuropathic pain and depressive-like conditions and most of the pro-inflammatory effects of TNF are mediated by the TNF receptor 1 (TNFR1). Here we sought to investigate: (1) the occurrence of depressive-like behavior in chronic neuropathic pain and the associated forms of hippocampal plasticity, and (2) the involvement of TNFR1-mediated TNF signaling as a possible regulator of such events. Neuropathic pain was induced by chronic constriction injury of the sciatic nerve in wild-type and TNFR1(-/-) mice. Anhedonia, weight loss and physical state were measured as symptoms of depression. Hippocampal neurogenesis, neuroplasticity, myelin remodeling and TNF/TNFRs expression were analyzed by immunohistochemical analysis and western blot assay. We found that neuropathic pain resulted in the development of depressive symptoms in a time dependent manner and was associated with profound hippocampal alterations such as impaired neurogenesis, reduced expression of neuroplasticity markers and myelin proteins. The onset of depressive-like behavior also coincided with increased hippocampal levels of TNF, and decreased expression of TNF receptor 2 (TNFR2), which were all fully restored after mice spontaneously recovered from pain. Notably, TNFR1(-/-) mice did not develop depressive-like symptoms after injury, nor were there changes in hippocampal neurogenesis and plasticity. Our data show that neuropathic pain induces a cluster of depressive-like symptoms and profound hippocampal plasticity that are dependent on TNF signaling through TNFR1.

Effort, symptom validity testing, performance validity testing and traumatic brain injury

BACKGROUND

To understand the neurocognitive effects of brain injury, valid neuropsychological test findings are paramount.

REVIEW

This review examines the research on what has been referred to a symptom validity testing (SVT). Above a designated cut-score signifies a 'passing' SVT performance which is likely the best indicator of valid neuropsychological test findings. Likewise, substantially below cut-point performance that nears chance or is at chance signifies invalid test performance. Significantly below chance is the sine qua non neuropsychological indicator for malingering. However, the interpretative problems with SVT performance below the cut-point yet far above chance are substantial, as pointed out in this review. This intermediate, border-zone performance on SVT measures is where substantial interpretative challenges exist. Case studies are used to highlight the many areas where additional research is needed. Historical perspectives are reviewed along with the neurobiology of effort. Reasons why performance validity testing (PVT) may be better than the SVT term are reviewed.

CONCLUSIONS

Advances in neuroimaging techniques may be key in better understanding the meaning of border zone SVT failure. The review demonstrates the problems with rigidity in interpretation with established cut-scores. A better understanding of how certain types of neurological, neuropsychiatric and/or even test conditions may affect SVT performance is needed.

Agmatine induces Nrf2 and protects against corticosterone effects in hippocampal neuronal cell line

Hyperactivation of the hypothalamic-pituitary-adrenal axis is a common finding in major depression; this may lead to increased levels of cortisol, which are known to cause oxidative stress imbalance and apoptotic neuronal cell death, particularly in the hippocampus, a key region implicated in mood regulation. Agmatine, an endogenous metabolite of L-arginine, has been proposed for the treatment of major depression. Corticosterone induced apoptotic cell death and increased ROS production in cultured hippocampal neuronal cells, effects that were abolished in a concentration- and time-dependent manner by agmatine. Interestingly, the combination of sub-effective concentrations of agmatine with fluoxetine or imipramine afforded synergic protection. The neuroprotective effect of agmatine was abolished by yohimbine (α2-adrenoceptor antagonist), ketanserin (5-HT2A receptor antagonist), LY294002 (PI3K inhibitor), PD98059 (MEK1/2 inhibitor), SnPP (HO-1 inhibitor), and cycloheximide (protein synthesis inhibitor). Agmatine increased Akt and ERK phosphorylation and induced the transcription factor Nrf2 and the proteins HO-1 and GCLc; induction of these proteins was prevented by yohimbine, ketanserin, LY294002, and PD98059. In conclusion, agmatine affords neuroprotection against corticosterone effects by a mechanism that implicates Nrf2 induction via α2-adrenergic and 5-HT2A receptors, Akt and ERK pathways, and HO-1 and GCLc expression.

Inflammatory cytokine-associated depression

Inflammatory cytokines can sometimes trigger depression in humans, are often associated with depression, and can elicit some behaviors in animals that are homologous to major depression. Moreover, these cytokines can affect monoaminergic and glutamatergic systems, supporting an overlapping pathoetiology with major depression. This suggests that there could be a specific major depression subtype, inflammatory cytokine-associated depression (ICAD), which may require different therapeutic approaches. However, most people do not develop depression, even when exposed to sustained elevations in inflammatory cytokines. Thus several vulnerabilities and sources of resilience to inflammation-associated depression have been identified. These range from genetic differences in neurotrophic and serotonergic systems to sleep quality and omega-3 fatty acid levels. Replicating these sources of resilience as treatments could be one approach for preventing "ICAD". This article is part of a Special Issue entitled SI: Neuroimmunology in Health And Disease.

Agmatine abolishes restraint stress-induced depressive-like behavior and hippocampal antioxidant imbalance in mice

Agmatine has been recently emerged as a novel candidate to assist the conventional pharmacotherapy of depression. The acute restraint stress (ARS) is an unavoidable stress situation that may cause depressive-like behavior in rodents. In this study, we investigated the potential antidepressant-like effect of agmatine (10mg/kg, administered acutely by oral route) in the forced swimming test (FST) in non-stressed mice, as well as its ability to abolish the depressive-like behavior and hippocampal antioxidant imbalance induced by ARS. Agmatine reduced the immobility time in the mouse FST (1-100mg/kg) in non-stressed mice. ARS caused an increase in the immobility time in the FST, indicative of a depressive-like behavior, as well as hippocampal lipid peroxidation, and an increase in the activity of hippocampal superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities, reduced catalase (CAT) activity and increased SOD/CAT ratio, an index of pro-oxidative conditions. Agmatine was effective to abolish the depressive-like behavior induced by ARS and to prevent the ARS-induced lipid peroxidation and changes in SOD, GR and CAT activities and in SOD/CAT activity ratio. Hippocampal levels of reduced glutathione (GSH) were not altered by any experimental condition. In conclusion, the present study shows that agmatine was able to abrogate the ARS-induced depressive-like behavior and the associated redox hippocampal imbalance observed in stressed restraint mice, suggesting that its antidepressant-like effect may be dependent on its ability to maintain the pro-/anti-oxidative homeostasis in the hippocampus.

Biological basis of suicide and suicidal behavior

OBJECTIVE

Suicide is a major public health concern as each year 30000 people die by suicide in the USA alone. In the teenage population, it is the second leading cause of death. There have been extensive studies of psychosocial factors associated with suicide and suicidal behavior. However, very little is known about the neurobiology of suicide. Recent research has provided some understanding of the neurobiology of suicide, which is the topic of this review.

METHODS

Neurobiology of suicide has been studied using peripheral tissues such as platelets, lymphocytes, and cerebrospinal fluid obtained from suicidal patients or from the postmortem brains of suicide victims.

RESULTS

These studies have provided encouraging information with regard to the neurobiology of suicide. They show an abnormality of the serotonergic mechanism, such as increased serotonin receptor subtypes and decreased serotonin metabolites (e.g. 5-hydroxyindoleacetic acid). These studies also suggest abnormalities of receptor-linked signaling mechanisms such as phosphoinositide and adenylyl cyclase. Other biological systems that appear to be dysregulated in suicide involve the hypothalamic-pituitary-adrenal axis, and neurotrophins and neurotrophin receptors. More recently, several studies have also indicated abnormalities of neuroimmune functions in suicide.

CONCLUSIONS

Some encouraging information emerged from the present review, primarily related to some of the neurobiological mechanisms mentioned above. It is hoped that neurobiological studies may eventually result in the identification of appropriate biomarkers for suicidal behavior as well as appropriate therapeutic targets for its treatment.

Central metabolite changes and activation of microglia after peripheral interleukin-2 challenge

Interleukin (IL)-2 regulates the immune response through the proliferation of activated T-cells and also exerts effects on the central nervous system (CNS). Alongside having marked neurobehavioral effects, IL-2 has been suggested to impact on various psychiatric disorders. The immune-CNS communication of IL-2 remains unclear, although, it is suggested that microglia are the source and target of IL-2. Here, we analyzed changes in brain metabolites following a peripheral IL-2 challenge and examined the contribution of microglia in mediating these effects. Rats were assessed by magnetic resonance spectroscopy (MRS) in a 9.4 T scanner for baseline metabolite levels in the prefrontal cortex (PFC) and the hippocampus. After 7 days animals were scanned again following a single injection of IL-2 (2.5 μg/kg) and then tested on the elevated plus-maze for the correlation of IL-2-induced brain metabolites and measures of anxiety. In another experiment CD25(+) microglia cells were determined. A separate group of rats was injected either with IL-2 or vehicle, and afterward the PFC and hippocampus were dissected and fluorescence activated cell sorting (FACS) analysis was performed. The MRS scans in the intra-individual study design showed a significant increase in myo-inositol in the analyzed regions. A significant correlation of anxiety-like measures and myo-inositol, a marker for microglia activity, was found in the hippocampus. The FACS analysis showed a significant increase in CD25(+) microglia in the hippocampus compared to controls. The results support the role of microglia as a mediator in the immune-CNS communication and the effects of peripheral IL-2.

Intracerebroventricular administration of HIV-1 Tat induces brain cytokine and indoleamine 2,3-dioxygenase expression: a possible mechanism for AIDS comorbid depression

Human immunodeficiency virus (HIV) remains a major public health concern despite a large education effort during the past 25 years. A persistent problem with HIV infection is the high comorbity rate of clinical depression. We previously established that increasing proinflammatory cytokines within the brain of mice induces sickness that can culminate in depressive-like behavior. Here we investigated the role of the HIV transactivator of transcription (Tat) protein in activation of brain cytokine signaling and subsequent induction of depressive-like behavior in a murine model. Adult Balb/c mice were administered a single intracerebroventricular (ICV) injection of Tat (40 ng). Social investigation of a novel juvenile was measured at 2, 4, 8 and 24 h post-treatment. Mice treated with Tat did not display signs of sickness, as measured by either decreased social investigation or loss of body weight. At 24 h post-injection, mice were subjected to the forced swim test (FST). ICV administration of Tat to Balb/c mice increased immobility in the FST at 24 h post injection. A different strain of mice, C57BL/6J, responded similarly in the FST. Furthermore, adult C57BL/6J mice injected with Tat and tested in a two-bottle 1% sucrose preference test displayed reduced preference for sucrose during the 24 h post-injection period. Subsequently, brain tissues from Tat-treated and control C57BL/6J mice were collected at 4 and 24 h post injection. CNS tissue from Tat-treated mice had increased expression of IL-1β, TNF-α, IL-6, and IDO mRNAs at 4 h post injection. These data demonstrate that a single exposure to Tat in the brain is sufficient to induce brain cytokine signaling that culminates in depressive-like behavior. The results reveal a potential role for Tat in the development of comorbid depression in HIV-infected individuals.

Anti-inflammatory signaling in schizophrenia

A great deal of interest has been centered upon activated inflammatory processes in schizophrenia and their contribution to disease-relevant brain and behavioral impairment. In contrast, the role of anti-inflammatory signaling has attracted somewhat less attention in this context. The present article focuses on the emerging role of anti-inflammatory signaling in schizophrenia and discusses the potential influence of altered anti-inflammatory activity on progressive inflammatory processes, physical and metabolic functions, and treatment effects related to the use of conventional antipsychotic drugs and immunomodulatory agents in the pharmacotherapy of schizophrenia. By reviewing existing evidence, it appears that enhanced anti-inflammatory activity has many faces in schizophrenia: On the one hand, it may effectively limit potentially harmful inflammatory processes and may contribute to the improvement of psychopathological symptoms, especially when the anti-inflammatory system is boosted at early stages of the disease. On the other hand, enhanced anti-inflammatory activity may render affected individuals more susceptible to distinct physiological abnormalities such as cardiovascular disease, and may further impede the resistance to specific infectious agents. Therefore, an enhancement of anti-inflammatory signaling in schizophrenia might not simply be said to be either advantageous or disadvantageous, but rather should be interpreted and dealt with in a context-dependent manner. Increased awareness of the multiple roles of anti-inflammatory signaling may readily help to reduce additional health burdens in schizophrenia, and at the same time, may provide opportunities to further explore the benefits associated with anti-inflammatory strategies in the symptomatological and/or preventive treatment of this disorder.

Inflammatory processes in schizophrenia: a promising neuroimmunological target for the treatment of negative/cognitive symptoms and beyond

Emerging evidence indicates that schizophrenia is associated with activated peripheral and central inflammatory responses. Such inflammatory processes seem to be influenced by a number of environmental and genetic predisposition factors, and they may critically depend on and contribute to the progressive nature of schizophrenic disease. There is also appreciable evidence to suggest that activated inflammatory responses can undermine disease-relevant affective, emotional, social, and cognitive functions, so that inflammatory processes may be particularly relevant for the precipitation of negative and cognitive symptoms of schizophrenia. Recent clinical trials of anti-inflammatory pharmacotherapy in this disorder provide promising results by showing superior beneficial treatment effects when standard antipsychotic drugs are co-administered with anti-inflammatory compounds, as compared with treatment outcomes using antipsychotic drugs alone. Given the limited efficacy of currently available antipsychotic drugs to ameliorate negative and cognitive symptoms, the further exploration of inflammatory mechanisms and anti-inflammatory strategies may open fruitful new avenues for improved treatment of symptoms undermining affective, emotional, social and cognitive functions pertinent to schizophrenic disease.

An intriguing and hitherto unexplained co-occurrence: Depression and chronic fatigue syndrome are manifestations of shared inflammatory, oxidative and nitrosative (IO&NS) pathways

There is a significant 'comorbidity' between depression and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Depressive symptoms frequently occur during the course of ME/CFS. Fatigue and somatic symptoms (F&S), like pain, muscle tension, and a flu-like malaise, are key components of depression. At the same time, depression and ME/CFS show major clinical differences, which allow to discriminate them with a 100% accuracy. This paper aims to review the shared pathways that underpin both disorders and the pathways that discriminate them. Numerous studies have shown that depression and ME/CFS are characterized by shared aberrations in inflammatory, oxidative and nitrosative (IO&NS) pathways, like systemic inflammation and its long-term sequels, including O&NS-induced damage to fatty acids, proteins and DNA; dysfunctional mitochondria; lowered antioxidant levels, like zinc and coenzyme Q10; autoimmune responses to neoepitopes formed by O&NS; lowered omega-3 polyunsaturated fatty acid levels; and increased translocation of gram-negative bacteria. Some IO&NS-related pathways, like the induction of indoleamine 2-3-dioxygenase, neurodegeneration and decreased neurogenesis, are more specific to depression, whereas other pathways, like the 2'-5' oligoadenylate synthetase/RNase L pathway, are specific to ME/CFS. Most current animal models of depression, e.g. those induced by cytokines, are not reminiscent of human depression but reflect a mixture of depressive and F&S symptoms. The latter symptoms, sometimes called sickness behavior, differ from depression and ME/CFS because the former is a (sub)acute response to infection-induced pro-inflammatory cytokines that aims to enhance recovery, whereas the latter are characterized by long-term sequels in multiple IO&NS pathways. Depression and ME/CFS are not 'comorbid' disorders, but should be regarded as 'co-associated disorders' that are clinical manifestations of shared pathways.

Multiple aberrations in shared inflammatory and oxidative & nitrosative stress (IO&NS) pathways explain the co-association of depression and cardiovascular disorder (CVD), and the increased risk for CVD and due mortality in depressed patients

There is evidence that there is a bidirectional relationship between major depression and cardiovascular disorder (CVD): depressed patients are a population at risk for increased cardiac morbidity and mortality, and depression is more frequent in patients who suffer from CVD. There is also evidence that inflammatory and oxidative and nitrosative stress (IO&NS) pathways underpin the common pathophysiology of both CVD and major depression. Activation of these pathways may increase risk for both disorders and contribute to shared risk. The shared IO&NS pathways that may contribute to CVD and depression comprise the following: increased levels of pro-inflammatory cytokines, like interleukin-1β (IL-1β), IL-2, IL-6, IL-8, IL-12, tumor necrosis factor-α, and interferon-γ; T cell activation; increased acute phase proteins, like C-reactive protein, haptoglobin, fibrinogen and α1-antitrypsin; complement factors; increased LPS load through bacterial translocation and subsequent gut-derived inflammation; induction of indoleamine 2,3-dioxygenase with increased levels of tryptophan catabolites; decreased levels of antioxidants, like coenzyme Q10, zinc, vitamin E, glutathione and glutathione peroxidase; increased O&NS characterized by oxidative damage to low density lipoprotein (LDL) and phospholipid inositol, increased malondialdehyde, and damage to DNA and mitochondria; increased nitrosative stress; and decreased ω3 polyunsaturated fatty acids (PUFAs). The complex interplay between the abovementioned IO&NS pathways in depression results in pro-atherogenic effects and should be regarded as a risk factor to future clinical CVD and due mortality. We suggest that major depression should be added as a risk factor to the Charlson "comorbidity" index. It is advised that patients with (sub)chronic or recurrent major depression should routinely be assessed by serology tests to predict if they have an increased risk to cardiovascular disorders.

Sertoli cell therapy: a novel possible treatment strategy for treatment-resistant major depressive disorder

By the year 2020, depression will be the 2nd most common health problem in the world. Current medications to treat depression are effective in less than 50% of patients. There is the need for novel treatments for depression to address the high rates of resistance to current treatment and the chronic residual symptoms in many patients treated for depression. The heterogeneity of major depressive disorder suggests that multiple neurocircuits and neurochemicals are involved in its pathogenesis thus, finding an alternative to neurotransmitter agonist- or antagonist-based treatments offers an important new approach. Cellular therapy is an emerging treatment strategy for multiple diseases, including depression. Based upon their in vivo function as "nurse cells" within the testis and the documented viability, efficacy, and safety of Sertoli cells transplanted into multiple tissues, including brain, the potential for these cells to provide a neuroprotective, anti-inflammatory, and trophic environment for neurons should be considered. It is proposed that the combination of self-protective, immunoregulatory and trophic properties of Sertoli cells may confer a unique potential for depression treatment and avoid many of the risks and challenges associated with stem cell therapies. At the very least, studies of the effects of Sertoli cell transplantation will add substantially to our understanding of the cellular and molecular processes that underlie depression.

The MRL/lpr mouse strain as a model for neuropsychiatric systemic lupus erythematosus

To date, CNS disease and neuropsychiatric symptoms of systemic lupus erythematosus (NP-SLE) have been understudied compared to end-organ failure and peripheral pathology. In this review, we focus on a specific mouse model of lupus and the ways in which this model reflects some of the most common manifestations and potential mechanisms of human NP-SLE. The mouse MRL lymphoproliferation strain (a.k.a. MRL/lpr) spontaneously develops the hallmark serological markers and peripheral pathologies typifying lupus in addition to displaying the cognitive and affective dysfunction characteristic of NP-SLE, which may be among the earliest symptoms of lupus. We suggest that although NP-SLE may share common mechanisms with peripheral organ pathology in lupus, especially in the latter stages of the disease, the immunologically privileged nature of the CNS indicates that early manifestations of particularly mood disorders maybe derived from some unique mechanisms. These include altered cytokine profiles that can activate astrocytes, microglia, and alter neuronal function before dysregulation of the blood-brain barrier and development of clinical autoantibody titres.

Influence of depression symptoms on serum tumor necrosis factor-α of patients with chronic low back pain

Introduction

Patients with chronic low back pain (cLBP) have high rates of comorbid psychiatric disorders, mainly depression. Recent evidence suggests that depressive symptoms and pain, as interacting factors, have an effect on the circulating levels of inflammatory markers relevant to coronary artery disease. Our previous work showed a higher serum level of an inflammatory marker tumour necrosis factor-alpha (TNFα) in patients with cLBP, which did not correlate with intensity of low back pain alone. In the present study we investigated the cross-sectional associations of depressive symptoms, low back pain and their interaction with circulating levels of TNFα.

Methods

Each group of 29 patients with cLBP alone or with both cLBP and depression was age-matched and sex-matched with 29 healthy controls. All subjects underwent a blood draw for the assessment of serum TNFα and completed a standardised questionnaire regarding medication, depression scores according to the German version of Centre for Epidemiological Studies Depression Scale (CES-D), pain intensity from a visual analogue scale, and back function using the Roland and Morris questionnaire. The correlations between TNFα level and these clinical parameters were analysed.

Results

There were no differences in TNFα level between cLBP patients with and without depression. Both cLBP patients with (median = 2.51 pg/ml, P = 0.002) and without (median = 2.58 pg/ml, P = 0.004) depression showed significantly higher TNFα serum levels than healthy controls (median = 0 pg/ml). The pain intensity reported by both patient groups was similar, while the patients with depression had higher CES-D scores (P < 0.001) and worse back function (P < 0.001). The variance analysis showed that the interaction between TNFα level and pain intensity, CES-D scores, sex, body mass index and medication was statistically significant.

Conclusions

Depression as a comorbidity to cLBP did not influence the serum TNFα level. It seems that TNFα somehow acts as a mediator in both cLBP and depression, involving similar mechanisms that will be interesting to follow in further studies.

What can post-mortem studies tell us about the pathoetiology of suicide?

Suicide is a major public health concern; however, its neurobiology is unclear. Post-mortem brain tissue obtained from suicide victims and normal controls offers a useful method for studying the neurobiology of suicide. Despite several limitations, these studies have offered important leads in the neurobiology of suicide. In this article, we discuss some important findings resulting from these studies, focusing on serotonergic mechanisms, signal transduction systems, neuroendocrine studies and immune function abnormalities in suicide. These studies suggest that abnormalities of certain receptor subtypes, components of signaling systems such as protein kinase C and protein kinase A, transcription factors such as cyclic AMP response element-binding protein and neurotrophins may play an important role in the pathophysiology of suicide. These studies also suggest abnormalities of hypothalamic-pituitary-adrenal axis system components, feedback mechanisms and cytokines, which are chemical mediators of the immune functions. Post-mortem brain tissue offers an opportunity for future studies, such as genetic and epigenetic studies.

Major depression during interferon-alpha treatment: vulnerability and prevention

Major Depressive Disorder (MDD) during interferons (IFN-α) treatment can occur within a few months of therapy, and shares many homologies with other forms of MDD, Most patients are resilient to the side effect ofinterferon-induced depression (IFN-MDD), but 15% to 40% are vulnerable. Several studies have employed antidepressants to prevent the incidence of an IFN-MDD episode, and the results suggest that prophylactic antidepressants may be specifically useful in those with pre-existing subthreshold depressive symptoms andlor a history of prior MDD episodes. Several other potential markers of vulnerability for IFN-MDD have been implicated in assessments of nondepressed patients before they start IFN-α These include poor sleep quality, premorbid elevations in inflammatory cytokines, genetic polymorphisms in the serotonin system, personality, and social support. The interplay of these factors strongly predicts who is at risk for IFN-MDD, and indicates several potentially modifiable targets for the personalized prevention of IFN-MDD,

Pain and depression: the egg and the chicken story revisited

The prevalence of pain in depressed individuals and the prevalence of depression in patients with pain are higher than when these conditions are considered individually. When pain is severe, impairs function, and/or is refractory to treatment, it is associated with more depressive symptoms and worse depression outcomes. Similarly, depression in patients with pain is associated with more complaints and greater functional impairment. Whether alleviation of pain helps depressive symptoms or, likewise, whether relief of depression improves pain, are questions still incompletely clarified. However, there is growing evidence that depression and pain share genetic factors, biological pathways and neurotransmitters. Thus, the most promising area of future research is elucidating the neurobiological alterations in pain pathways that intersect with those involved in depression.

The inflammatory & neurodegenerative (I&ND) hypothesis of depression: leads for future research and new drug developments in depression

Despite extensive research, the current theories on serotonergic dysfunctions and cortisol hypersecretion do not provide sufficient explanations for the nature of depression. Rational treatments aimed at causal factors of depression are not available yet. With the currently available antidepressant drugs, which mainly target serotonin, less than two thirds of depressed patients achieve remission. There is now evidence that inflammatory and neurodegenerative (I&ND) processes play an important role in depression and that enhanced neurodegeneration in depression may-at least partly-be caused by inflammatory processes. Multiple inflammatory-cytokines, oxygen radical damage, tryptophan catabolites-and neurodegenerative biomarkers have been established in patients with depression and these findings are corroborated by animal models of depression. A number of vulnerability factors may predispose towards depression by enhancing inflammatory reactions, e.g. lower peptidase activities (dipeptidyl-peptidase IV, DPP IV), lower omega-3 polyunsaturated levels and an increased gut permeability (leaky gut). The cytokine hypothesis considers that external, e.g. psychosocial stressors, and internal stressors, e.g. organic inflammatory disorders or conditions, such as the postpartum period, may trigger depression via inflammatory processes. Most if not all antidepressants have specific anti-inflammatory effects, while restoration of decreased neurogenesis, which may be induced by inflammatory processes, may be related to the therapeutic efficacy of antidepressant treatments. Future research to disentangle the complex etiology of depression calls for a powerful paradigm shift, i.e. by means of a high throughput-high quality screening, including functional genetics and genotyping microarrays; established and novel animal and ex vivo-in vitro models for depression, such as new transgenic mouse models and endophenotype-based animal models, specific cell lines, in vivo and ex vivo electroporation, and organotypic brain slice culture models. This screening will allow to: 1) discover new I&ND biomarkers, both at the level of gene expression and the phenotype; and elucidate the underlying molecular I&ND pathways causing depression; and 2) identify new therapeutic targets in the I&ND pathways; develop new anti-I&ND drugs for these targets; select existing anti-I&ND drugs or substances that could augment the efficacy of antidepressants; and predict therapeutic response by genetic I&ND profiles.

Affective Disorders, Bone Metabolism, and Osteoporosis

The nature of the relationship between affective disorders, bone mineral density (BMD), and bone metabolism is unresolved, although there is growing evidence that many medications used to treat affective disorders are associated with low BMD or alterations in neuroendocrine systems that influence bone turnover. The objective of this review is to describe the current evidence regarding the association of unipolar and bipolar depression with BMD and indicators of bone metabolism, and to explore potential mediating and confounding influences of those relationships. The majority of studies of unipolar depression and BMD indicate that depressive symptoms are associated with low BMD. In contrast, evidence regarding the relationship between bipolar depression and BMD is inconsistent. There is limited but suggestive evidence to support an association between affective disorders and some markers of bone turnover. Many medications used to treat affective disorders have effects on physiologic systems that influence bone metabolism, and these conditions are also associated with a range of health behaviors that can influence osteoporosis risk. Future research should focus on disentangling the pathways linking psychotropic medications and their clinical indications with BMD and fracture risk.

Photoperiodic regulation of behavioral responses to bacterial and viral mimetics: a test of the winter immunoenhancement hypothesis

Siberian hamsters (Phodopus sungorus) exhibit changes in immune function following adaptation to short photoperiods, including a marked attenuation of energetically expensive thermoregulatory and behavioral responses to gram-negative bacterial infections. Whether this seasonal attenuation of the immune response is idiosyncratic to gram-negative infections or is representative of innate immune responses in general is not known. If seasonal attenuation of responsiveness to infection is indeed driven primarily by anticipation of energetic constraints, then one would predict that responsiveness to all pathogens would be diminished during short days. If, on the other hand, seasonal changes in responsiveness to infection reflect anticipation of specific pathogens that are common at different phases of the annual cycle, then one would expect short photoperiods to attenuate responsiveness to some pathogens and long photoperiods to attenuate responsiveness to others. To resolve this issue, we exposed male Siberian hamsters to either long or short photoperiods for 11 weeks, then examined their behavioral sickness responses to compounds that represent the minimally immunogenic components of gram-negative bacterial (lipopolysaccharide), gram-positive bacterial (muramyl dipeptide), and viral (polyinosinepolycytidylic acid) organisms. Hamsters exhibited anorexic, anhedonic, ponderal, and/or thermoregulatory sickness behaviors to all 3 pathogen mimetics, but in all cases in which sickness responses were evident, they were attenuated in short days. Energetically costly behavioral responses to several distinct classes of infectious organisms are attenuated in anticipation of winter. The data are not consistent with a pathogen-specific seasonal modulation of innate immune responses.

Pro-inflammatory cytokines and treatment response to escitalopram in major depressive disorder

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.

Depressive symptoms in patients with chronic hepatitis C are correlated with elevated plasma levels of interleukin-1beta and tumor necrosis factor-alpha

Studies suggest that cytokines have a role in the biology of depression. In this study, we evaluated depression and cytokine levels in patients with and without chronic hepatitis C (HCV) to better assess how chronic infection alters cytokines levels and may contribute to depressive symptomotology. Twenty-three adults with (n=16) and without (n=7) HCV were recruited through the Portland VA Medical Center. Research participants were excluded for current substance abuse, psychotic disorder, liver cirrhosis, or interferon (IFN) therapy. Participants completed the Beck Depression Inventory-II (BDI-II) and a blood draw to evaluate plasma cytokine levels [i.e., interleukin (IL)-1beta, IL-10 and tumor necrosis factor (TNF)-alpha]. t-Tests were performed to compare cytokine levels in patients with or without HCV. HCV patients showed higher TNF-alpha values compared to patients without HCV (group means=7.94 vs. 3.41pg/mL, respectively, p=0.047). There were no significant differences between the groups for the other cytokines assessed. In patients with HCV, TNF-alpha and IL-1beta levels (but not IL-10) were correlated with BDI-II scores [r=0.594, p=0.020 and r=0.489, p=0.055 (trend), respectively]. Taken together, these results show an association between severity of depressive symptoms and expression of pro-inflammatory cytokines in patients with HCV. Future studies should investigate how inflammatory mediators play a role in the expression of specific depressive symptoms in patients with chronic infection. Patients with HCV represent an interesting model to examine this relationship.