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

Multimodal brain-derived subtypes of Major depressive disorder differentiate patients for anergic symptoms, immune-inflammatory markers, history of childhood trauma and treatment-resistance

An estimated 30 % of Major Depressive Disorder (MDD) patients exhibit resistance to conventional antidepressant treatments. Identifying reliable biomarkers of treatment-resistant depression (TRD) represents a major goal of precision psychiatry, which is hampered by the clinical and biological heterogeneity. To uncover biologically-driven subtypes of MDD, we applied an unsupervised data-driven framework to stratify 102 MDD patients on their neuroimaging signature, including extracted measures of cortical thickness, grey matter volumes, and white matter fractional anisotropy. Our novel analytical pipeline integrated different machine learning algorithms to harmonize data, perform data dimensionality reduction, and provide a stability-based relative clustering validation. The obtained clusters were characterized for immune-inflammatory peripheral biomarkers, TRD, history of childhood trauma and depressive symptoms. Our results indicated two different clusters of patients, differentiable with 67 % of accuracy: one cluster (n = 59) was associated with a higher proportion of TRD, and higher scores of energy-related depressive symptoms, history of childhood abuse and emotional neglect; this cluster showed a widespread reduction in cortical thickness (d = 0.43-1.80) and volumes (d = 0.45-1.05), along with fractional anisotropy in the fronto-occipital fasciculus, stria terminalis, and corpus callosum (d = 0.46-0.52); the second cluster (n = 43) was associated with cognitive and affective depressive symptoms, thicker cortices and wider volumes. Multivariate analyses revealed distinct brain-inflammation relationships between the two clusters, with increase in pro-inflammatory markers being associated with decreased cortical thickness and volumes. Our stratification of MDD patients based on structural neuroimaging identified clinically-relevant subgroups of MDD with specific symptomatic and immune-inflammatory profiles, which can contribute to the development of tailored personalized interventions for MDD.

Peripheral inflammatory markers in melancholic versus non-melancholic depression

BACKGROUND

Peripheral inflammation has been associated with major depression, however there is a paucity of studies examining whether inflammatory profiles differ across depressive subtypes. The current study sought to compare peripheral inflammatory markers in patients with melancholic versus non-melancholic depression and with healthy controls.

METHOD

Eighty outpatients with a current major depressive episode (MDE) were assigned as having a melancholic or a non-melancholic depressive subtype based on clinician diagnosis and the Sydney Melancholic Prototypic Index (SMPI). Participants provided peripheral venous blood from which plasma levels of cytokines and other inflammatory markers (C-reactive protein (CRP), neutrophil/lymphocyte ratio, plasma cytokines) were compared across the two patient groups and also to a group of 81 age-matched healthy controls.

RESULTS

Patients with melancholic and non-melancholic depression demonstrated increased CRP and decreased interferon-gamma (IFN-γ) levels compared to controls. Using clinician diagnosis of subtype, interleukin-12 (IL-12) and interleukin-10 (IL-10) levels were elevated in melancholic patients versus non-melancholic and control groups, with no differences found for the other measured markers of inflammation.

CONCLUSION

Study findings demonstrate shared inflammatory changes across certain inflammatory markers (CRP and IFN-γ) and increases in IL-12 and IL-10 levels specific to melancholic depression. While generally supportive of previous work, our peripheral inflammation findings in melancholic depression are relatively novel and suggest this subgroup may benefit from anti-inflammatory therapies. Further studies are required to replicate these findings.

Sex-specific immune-inflammatory markers and lipoprotein profile in patients with anhedonia with unipolar and bipolar depression

BACKGROUND

Anhedonia is a core symptom in patients with unipolar and bipolar depression. However, sex-specific markers reflecting biological heterogeneity are lacking. Emerging evidence suggests that sex differences in immune-inflammatory markers and lipoprotein profiles are associated with anhedonia.

METHODS

The demographic and clinical data, immune-inflammatory markers (CD3, CD4, and CD8), and lipoprotein profiles [TC, TG, LDL-C, HDL-C, lipoprotein(a) Lp (a)] of 227 patients with unipolar and bipolar depression were collected. The Hamilton Depression Rating Scale (HAMD) and Snaith-Hamilton Pleasure Scale (SHAPS) were used to assess depression and anhedonia symptoms. Data were analyzed using ANOVA, logistic regression, and receiver operating characteristic curves.

RESULTS

Male patients in the anhedonia group had higher levels of CD3, CD4, and CD8, and lower levels of Lp (a) than the non-anhedonia group, while no significant difference was identified in female patients with and without anhedonia. Logistic regression analysis showed that CD3, CD4, CD8, and Lp (a) levels were associated with anhedonia in male patients. Furthermore, the combination of CD3, CD4, CD8, and Lp (a) had the strongest predictive value for distinguishing anhedonia in male patients than individual parameters.

CONCLUSIONS

We identified sex-specific associations between immune-inflammatory markers, lipoprotein profiles, and anhedonia in patients with unipolar and bipolar depression. The combination of CD3, CD4, CD8, and Lp (a) might be a possible biomarker for identifying anhedonia in male patients with unipolar and bipolar depression.

Differentiating melancholic and non-melancholic depression via biological markers: A review

OBJECTIVES

Melancholia is a severe form of depression that is typified by greater genetic and biological influence, distinct symptomatology, and preferential response to physical treatment. This paper sought to broadly overview potential biomarkers of melancholia to benefit differential diagnosis, clinical responses and treatment outcomes. Given nuances in distinguishing melancholia as its own condition from other depressive disorder, we emphasised studies directly comparing melancholic to non-melancholic depression.

METHODS

A comprehensive literature search was conducted. Key studies were identified and summarised qualitatively.

RESULTS

105 studies in total were identified. These studies covered a wide variety of biomarkers, and largely fell into three domains: endocrinological (especially cortisol levels, particularly in response to the dexamethasone suppression test), neurological, and immunological (particularly inflammatory markers). Less extensive evidence also exists for metabolic, genetic, and cardiovascular markers.

CONCLUSIONS

Definitive conclusions were predominantly limited due to substantial heterogeneity in how included studies defined melancholia. Furthermore, this heterogeneity could be responsible for the between- and within-group variability observed in the candidate biomarkers that were examined. Therefore, clarifying these definitional parameters may help identify underlying patterns in biomarker expression to improve diagnostic and therapeutic precision for the depressive disorders.

Stability of the Subtypes of Major Depressive Disorder in Older Adults and the Influence of Mild Cognitive Impairment on the Stability

OBJECTIVES

To assess 1) the longitudinal stability of the atypical, melancholic, combined atypical-melancholic and the unspecified subtypes of major depressive disorder (MDD) according to the diagnostic and statistical manual of mental disorders (DSM -IV) specifiers in older adults, and 2) the effect of mild cognitive impairment (MCI) on the stability of these subtypes.

DESIGN

Prospective cohort study with a 5.1 year-follow-up.

SETTING

Population-based cohort from Lausanne, Switzerland.

PARTICIPANTS

A total of 1,888 participants (mean age: 61.7 years, women: 69.2%) with at least two psychiatric evaluations, one after the age of 65 years.

MEASUREMENTS

Semistructured diagnostic interview to assess lifetime and 12-month DSM-IV Axis-1 disorders at each investigation and neuro-cognitive tests to identify MCI in participants aged 65 years and over. Associations between lifetime MDD status before and 12-month depression status after the follow-up were assessed using multinomial logistic regression. The effect of MCI on these associations was assessed by testing interactions between MDD subtypes and MCI status.

RESULTS

1) Associations between depression status before and after the follow-up were observed for atypical (adjusted OR [95% CI] = 7.99 [3.13; 20.44]), combined (5.73 [1.50; 21.90]) and unspecified (2.14 [1.15; 3.98]), but not melancholic MDD (3.36 [0.89; 12.69]). However, there was a certain degree of overlap across the subtypes, particularly between melancholic MDD and the other subtypes. 2) No significant interactions were found between MCI and lifetime MDD subtypes regarding depression status after follow-up.

CONCLUSION

The strong stability of the atypical subtype in particular highlights the need for identifying this subtype in clinical and research settings, given its well-documented links to inflammatory and metabolic markers.

Rice Germ Attenuates Chronic Unpredictable Mild Stress-Induced Muscle Atrophy

Chronic stress leads to hypothalamic-pituitary-adrenal axis dysfunction, increasing cortisol levels. Glucocorticoids (GCs) promote muscle degradation and inhibit muscle synthesis, eventually causing muscle atrophy. In this study, we aimed to evaluate whether rice germ supplemented with 30% γ-aminobutyric acid (RG) attenuates muscle atrophy in an animal model of chronic unpredictable mild stress (CUMS). We observed that CUMS raised the adrenal gland weight and serum adrenocorticotropic hormone (ACTH) and cortisol levels, and these effects were reversed by RG. CUMS also enhanced the expression of the GC receptor (GR) and GC-GR binding in the gastrocnemius muscle, which were attenuated by RG. The expression levels of muscle degradation-related signaling pathways, such as the Klf15, Redd-1, FoxO3a, Atrogin-1, and MuRF1 pathways, were enhanced by CUMS and attenuated by RG. Muscle synthesis-related signaling pathways, such as the IGF-1/AKT/mTOR/s6k/4E-BP1 pathway, were reduced by CUMS and enhanced by RG. Moreover, CUMS raised oxidative stress by enhancing the levels of iNOS and acetylated p53, which are involved in cell cycle arrest, whereas RG attenuated both iNOS and acetylated p53 levels. Cell proliferation in the gastrocnemius muscle was reduced by CUMS and enhanced by RG. The muscle weight, muscle fiber cross-sectional area, and grip strength were reduced by CUMS and enhanced by RG. Therefore, RG attenuated ACTH levels and cortisol-related muscle atrophy in CUMS animals.

Abnormal dynamic functional connectivity of hippocampal subregions associated with working memory impairment in melancholic depression

BACKGROUND

Previous studies have demonstrated structural and functional changes of the hippocampus in patients with major depressive disorder (MDD). However, no studies have analyzed the dynamic functional connectivity (dFC) of hippocampal subregions in melancholic MDD. We aimed to reveal the patterns for dFC variability in hippocampus subregions - including the bilateral rostral and caudal areas and its associations with cognitive impairment in melancholic MDD.

METHODS

Forty-two treatment-naive MDD patients with melancholic features and 55 demographically matched healthy controls were included. The sliding-window analysis was used to evaluate whole-brain dFC for each hippocampal subregions seed. We assessed between-group differences in the dFC variability values of each hippocampal subregion in the whole brain and cognitive performance on the MATRICS Consensus Cognitive Battery (MCCB). Finally, association analysis was conducted to investigate their relationships.

RESULTS

Patients with melancholic MDD showed decreased dFC variability between the left rostral hippocampus and left anterior lobe of cerebellum compared with healthy controls (voxel p < 0.005, cluster p < 0.0125, GRF corrected), and poorer cognitive scores in working memory, verbal learning, visual learning, and social cognition (all p < 0.05). Association analysis showed that working memory was positively correlated with the dFC variability values of the left rostral hippocampus-left anterior lobe of the cerebellum (r = 0.338, p = 0.029) in melancholic MDD.

CONCLUSIONS

These findings confirmed the distinct dynamic functional pathway of hippocampal subregions in patients with melancholic MDD, and suggested that the dysfunction of hippocampus-cerebellum connectivity may be underlying the neural substrate of working memory impairment in melancholic MDD.

Non-steroidal anti-inflammatory drug target gene associations with major depressive disorders: a Mendelian randomisation study integrating GWAS, eQTL and mQTL Data

Previous observational studies reported associations between non-steroidal anti-inflammatory drugs (NSAIDs) and major depressive disorder (MDD), however, these associations are often inconsistent and underlying biological mechanisms are still poorly understood. We conducted a two-sample Mendelian randomisation (MR) study to examine relationships between genetic variants and NSAID target gene expression or DNA methylation (DNAm) using publicly available expression, methylation quantitative trait loci (eQTL or mQTL) data and genetic variant-disease associations from genome-wide association studies (GWAS of MDD). We also assessed drug exposure using gene expression and DNAm levels of NSAID targets as proxies. Genetic variants were robustly adjusted for multiple comparisons related to gene expression, DNAm was used as MR instrumental variables and GWAS statistics of MDD as the outcome. A 1-standard deviation (SD) lower expression of NEU1 in blood was related to lower C-reactive protein (CRP) levels of -0.215 mg/L (95% confidence interval (CI): 0.128-0.426) and a decreased risk of MDD (odds ratio [OR] = 0.806; 95% CI: 0.735-0.885; p = 5.36 × 10^-6). A concordant direction of association was also observed for NEU1 DNAm levels in blood and a risk of MDD (OR = 0.886; 95% CI: 0.836-0.939; p = 4.71 × 10^-5). Further, the genetic variants associated with MDD were mediated by NEU1 expression via DNAm (β = -0.519; 95% CI: -0.717 to -0.320256; p = 3.16 × 10^-7). We did not observe causal relationships between inflammatory genetic marker estimations and MDD risk. Yet, we identified a concordant association of NEU1 messenger RNA and an adverse direction of association of higher NEU1 DNAm with MDD risk. These results warrant increased pharmacovigilance and further in vivo or in vitro studies to investigate NEU1 inhibitors or supplements for MDD.

Peripheral Inflammatory Markers in Subtypes and Core Features of Depression: A Systematized Review

INTRODUCTION

The aim of this work was to summarize relationships between two subtypes of major depressive disorder (melancholic and atypical) and four core features of depression that reflect the domains identified consistently in previous studies of major depressive disorder endophenotypes (exaggerated reactivity to negative information, altered reward processing, cognitive control deficits, and somatic symptoms) on the one hand and selected peripheral inflammatory markers (C-reactive protein [CRP], cytokines, and adipokines) on the other.

METHODS

A systematized review was conducted. The database used for searching articles was PubMed (MEDLINE).

RESULTS

According to our search, most peripheral immunological markers associated with major depressive disorder are not specific to a single depressive symptom group. The most evident examples are CRP, IL-6, and TNF-α. The strongest evidence supports the connection of peripheral inflammatory markers with somatic symptoms; weaker evidence indicates a role of immune changes in altered reward processing. The least amount of evidence was found for the role of peripheral inflammatory markers in exaggerated reactivity to negative information and cognitive control deficits. Regarding the depression subtypes, a tendency for higher CRP and adipokines was observed in atypical depression; increased IL-6 was found in melancholic depression.

CONCLUSION

Somatic symptoms of depression could be a manifestation of a specific immunological endophenotype of depressive disorder. Melancholic and atypical depression may be characterized by different profiles of immunological markers.

Anti-Inflammatory Therapy as a Promising Target in Neuropsychiatric Disorders

This chapter analyzes the therapeutic potential of current anti-inflammatory drugs in treating psychiatric diseases from a neuro-immunological perspective. Based on the bidirectional brain-immune system relationship, the rationale is that a dysregulated inflammation contributes to the pathogenesis of psychiatric and neurological disorders, while the immunology function is associated with psychological variables like stress, affective disorders, and psychosis. Under certain social, psychological, and environmental conditions and biological factors, a healthy inflammatory response and the associated "sickness behavior," which are aimed to resolve a physical injury and microbial threat, become harmful to the central nervous system. The features and mechanisms of the inflammatory response are described across the main mental illnesses with a special emphasis on the profile of cytokines and the function of the HPA axis. Next, it is reviewed the potential clinical utility of immunotherapy (cytokine agonists and antagonists), glucocorticoids, unconventional anti-inflammatory agents (statins, minocycline, statins, and polyunsaturated fatty acids (PUFAs)), the nonsteroidal anti-inflammatory drugs (NSAIDs), and particularly celecoxib, a selective cyclooxygenase-2 (Cox-2) inhibitor, as adjuvants of conventional psychiatric medications. The implementation of anti-inflammatory therapies holds great promise in psychiatry. Because the inflammatory background may account for the etiology and/or progression of psychiatric disorders only in a subset of patients, there is a need to elucidate the immune underpinnings of the mental illness progression, relapse, and remission. The identification of immune-related bio-signatures will ideally assist in the stratification of the psychiatric patient to predict the risk of mental disease, the prognosis, and the response to anti-inflammatory therapy.

Forgetful, sad and old: Do vascular cognitive impairment and depression share a common pre-disease network and how is it impacted by ageing?

Vascular cognitive impairment (VCI) and depression frequently coexist in geriatric populations and reciprocally increase disease risks. We assert that a shared pre-disease state of the psycho-immune-neuroendocrine (PINE) network model mechanistically explains bidirectional associations between VCI and depression. Five pathophysiological sub-networks are identified that are shared by VCI and depression: neuroinflammation, kynurenine pathway imbalance, hypothalamic-pituitary-adrenal (HPA) axis overactivity, impaired neurotrophic support and cerebrovascular dysfunction. These do not act independently, and their complex interactions necessitate a systems biology approach to better define disease pathogenesis. The PINE network is already established in the context of non-communicable diseases (NCDs) such as depression, hypertension, atherosclerosis, coronary heart disease and type 2 diabetes mellitus. We build on previous literature to specifically explore mechanistic links between MDD and VCI in the context of PINE pathways and discuss key mechanistic commonalities linking these comorbid conditions and identify a common pre-disease state which precedes transition to VCI and MDD. We expand the model to incorporate bidirectional interactions with biological ageing. Diathesis factors for both VCI and depression feed into this network and the culmination of shared mechanisms (on an ageing substrate) lead to a critical network transition to one or both disease states. A common pre-disease state underlying VCI and depression can provide clinicians a unique opportunity for early risk assessment and intervention in disease development. Establishing the mechanistic elements and systems biology of this network can reveal early warning or predictive biomarkers together with novel therapeutic targets. Integrative studies are recommended to elucidate the dynamic networked biology of VCI and depression over time.

The role of inflammatory markers and cortisol in the association between early social cognition abilities and later internalising or externalising problems: Evidence from a UK birth cohort

OBJECTIVE

Deficits in social cognition are associated with internalising (emotional and peer problems) and externalising (conduct problems and hyperactivity/inattention) symptoms in youth. It has been suggested that stress may be one of the mechanisms underlying these associations. However, no empirical studies have investigated if physiological stress can explain the prospective associations between social cognition deficits and internalising and externalising symptoms in the general youth population. This study addressed this question and focused on two indicators of physiological stress, dysregulated diurnal cortisol patterns and systemic inflammation.

METHOD

Participants were 714 individuals from the Avon Longitudinal Study of Parents and Children (ALSPAC), a UK population-based birth cohort. Bayesian structural equation modelling was used to investigate a) the associations of social cognition abilities at ages 8, 11, and 14 years with internalising and externalising problems at age 17 years and b) the potential mediating effects of cortisol parameters at age 15 years and inflammatory markers [interleukin 6 (IL-6) and C-reactive protein (CRP)] at ages 9 and 16 years.

RESULTS

We found that social cognition difficulties were associated with later internalising and externalising problems. Flattened diurnal cortisol slope was associated with hyperactivity/inattention problems two years later. Lower morning cortisol partially mediated the direct association between social communication deficits at 8 years and hyperactivity/inattention and conduct problems at 17 years, even after adjustments for inflammation and confounders (for hyperactivity/inattention: indirect effect = 0.07, 95% CI [0.00, 0.18], p = .042; for conduct problems: indirect effect = 0.04, 95% CI [0.00, 0.11], p = .040). We did not find a significant association between systemic inflammation and social cognition difficulties, internalising problems, or externalising problems.

CONCLUSION

Our findings suggest that part of the effect of social communication difficulties in childhood on externalising problems in adolescence was mediated by lower morning cortisol. Hence, our study indicates that the hypoactivity of the hypothalamic-pituitary-adrenal (HPA) axis may be one of the physiological mechanisms linking some social cognition deficits to externalising problems.

Gut Bless Your Pain—Roles of the Gut Microbiota, Sleep, and Melatonin in Chronic Orofacial Pain and Depression

Background. Increased attention has been paid to the gut–brain axis recently, but little is known so far regarding how this translates into pain susceptibility. Aim. The aim of this review is to determine whether gastroenterological disorders and sleep disorders (directly or indirectly) contribute to an increased susceptibility to depression and chronic orofacial pain. Method. A search was performed in the U.S. National Library of Medicine (PubMed) database in order to find studies published before 19 December 2021. We used the following terms: gut microbiome, OR sleep quality, OR melatonin, OR GERD, OR IBS, AND: depression OR chronic pain, in different configurations. Only papers in English were selected. Given the large number of papers retrieved in the search, their findings were described and organized narratively. Results. A link exists between sleep disorders and gastroenterological disorders, which, by adversely affecting the psyche and increasing inflammation, disturb the metabolism of tryptophan and cause excessive microglial activation, leading to increased susceptibility to pain sensation and depression. Conclusions. Pain therapists should pay close attention to sleep and gastrointestinal disorders in patients with chronic pain and depression.

Inflammatory Markers in Substance Use and Mood Disorders: A Neuroimaging Perspective

Chronic exposure to addictive drugs in substance use disorders and stressors in mood disorders render the brain more vulnerable to inflammation. Inflammation in the brain, or neuroinflammation, is characterized by gliosis, microglial activation, and sustained release of cytokines, chemokines, and pro-inflammatory factors compromising the permeability of the blood-brain barrier. There is increased curiosity in understanding how substance misuse and/or repeated stress exposure affect inflammation and contribute to abnormal neuronal activity, altered neuroplasticity, and impaired cognitive control, which eventually promote compulsive drug-use behaviors and worsen mood disorders. This review will emphasize human imaging studies to explore the link between brain function and peripheral markers of inflammation in substance use disorders and mood disorders.

Comparisons of Serum Interleukin-8 Levels in Major Depressive Patients With Drug-Free Versus SSRIs Versus Healthy Controls

OBJECTIVE

The interleukin-8 (IL-8) has been reported to play an important role in depression, which might be modulated by the selective serotonin reuptake inhibitors (SSRIs). Thus, the aim of this study was to investigate serum IL-8 levels, depressive symptom, and their associations in drug-free MDD patients, MDD patients with SSRIs, and healthy controls (HCs).

METHODS

Fifty-seven drug-free MDD patients (male/female = 35/22, mean age: 39.24 years), 30 MDD patients with SSRIs (male/female = 11/19, mean age: 39.73 years), and 101 HCs (male/female = 52/49, mean age: 37.38 years) were recruited in this cross-sectional study. Serum IL-8 levels and depressive symptom were assessed using the Flow Cytometer and Hamilton Depression Scale (HAMD). The analysis of variance was used for the comparison between groups. The relationship between serum log₁₀ IL-8 levels and HAMD score was analyzed by Pearson correlation.

RESULTS

Serum log₁₀IL-8 levels were lower in all patients than HCs after controlling for covariates (F = 4.86, p = 0.03). There was significant difference in serum Log₁₀IL-8 levels among three groups after controlling for covariates (F = 14.63, p < 0.001). Serum Log₁₀IL-8 levels in drug-free patients were lower compared to HCs (F = 19.38, p < 0.001) or patients with SSRIs (F = 21.89, p < 0.001) after controlling for covariates. However, there was not difference in serum log₁₀IL-8 levels between patients with SSRIs and HCs after controlling for covariates. Moreover, serum Log₁₀IL-8 levels were negatively correlated with HAMD score in all patients (r = -0.37, p = 0.02). Also, serum Log₁₀IL-8 levels were negatively correlated with HAMD score in drug-free patients (r = -0.74, p = 0.01), but not in patients with SSRIs.

CONCLUSION

Our data supported that the decline in serum IL-8 levels was association with depression. Moreover, the SSRIs might modulate increased serum IL-8 levels of depression.

No evidence for clinical efficacy of adjunctive celecoxib with vortioxetine in the treatment of depression: A 6-week double-blind placebo controlled randomized trial

Given the role of low-grade inflammation in the pathophysiology of major depressive disorder (MDD), anti-inflammatory strategies may improve treatment outcomes in some patients. However, it is controversial whether they can be used as adjunctive treatments and whether pre-treatment levels of inflammation can predict treatment outcomes. This study was conducted to measure the efficacy of anti-inflammatory augmentation of antidepressant treatment in MDD patients; and to investigate whether treatment response was dependent on baseline inflammation levels. This parallel-group randomised, double-blind, placebo-controlled trial was conducted at the University of Adelaide (Australia). Participants with MDD were randomised to receive vortioxetine with celecoxib or vortioxetine with placebo for six weeks, and baseline blood high sensitivity C reactive protein levels were measured. Primary outcome was change in depressive symptoms (Montgomery-Åsberg Depression Rating Scale) and secondary outcomes included change in cognition (THINC-integrated tool - Codebreaker task) and functioning (Functioning Assessment Short Test) over 6 weeks. There was no evidence of superior efficacy of celecoxib augmentation over placebo on depressive symptom severity, response and remission rates, cognition and psychosocial functioning. There was also no evidence that pre-treatment inflammation levels modified the effect of celecoxib augmentation versus placebo. This observed lack of efficacy of celecoxib add-on does not support the use of celecoxib augmentation of antidepressants in the treatment of MDD in a cohort that mostly comprises treatment-resistant individuals. Additionally, C-reactive protein may not be suitable to predict treatment selection and response in MDD. The study was registered on the Australian New Zealand Clinical Trials Registry: ACTRN12617000527369 (www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=12617000527369p).

Periodontal Pathogens and Neuropsychiatric Health

Increasing evidence incriminates low-grade inflammation in cardiovascular, metabolic diseases, and neuropsychiatric clinical conditions, all important causes of morbidity and mortality. One of the upstream and modifiable precipitants and perpetrators of inflammation is chronic periodontitis, a polymicrobial infection with Porphyromonas gingivalis (P. gingivalis) playing a central role in the disease pathogenesis. We review the association between P. gingivalis and cardiovascular, metabolic, and neuropsychiatric illness, and the molecular mechanisms potentially implicated in immune upregulation as well as downregulation induced by the pathogen. In addition to inflammation, translocation of the pathogens to the coronary and peripheral arteries, including brain vasculature, and gut and liver vasculature has important pathophysiological consequences. Distant effects via translocation rely on virulence factors of P. gingivalis such as gingipains, on its synergistic interactions with other pathogens, and on its capability to manipulate the immune system via several mechanisms, including its capacity to induce production of immune-downregulating micro-RNAs. Possible targets for intervention and drug development to manage distal consequences of infection with P. gingivalis are also reviewed.

Dietary Patterns are Differentially Associated with Atypical and Melancholic Subtypes of Depression

Diet has been associated with the risk of depression, whereas different subtypes of depression have been linked with different cardiovascular risk factors (CVRFs). In this study, our aims were to (1) identify dietary patterns with exploratory factor analysis, (2) assess cross-sectional associations between dietary patterns and depression subtypes, and (3) examine the potentially mediating effect of dietary patterns in the associations between CVRFs and depression subtypes. In the first follow-up of the population-based CoLaus|PsyCoLaus study (2009–2013, 3554 participants, 45.6% men, mean age 57.5 years), a food frequency questionnaire assessed dietary intake and a semi-structured interview allowed to characterize major depressive disorder into current or remitted atypical, melancholic, and unspecified subtypes. Three dietary patterns were identified: Western, Mediterranean, and Sweet-Dairy. Western diet was positively associated with current atypical depression, but negatively associated with current and remitted melancholic depression. Sweet-Dairy was positively associated with current melancholic depression. However, these dietary patterns did not mediate the associations between CVRFs and depression subtypes. Hence, although we could show that people with different subtypes of depression make different choices regarding their diet, it is unlikely that these differential dietary choices account for the well-established associations between depression subtypes and CVRFs.

Ibuprofen Protection Against Restrained Chronic Stress-induced Depression in Male Rats

Introduction:

Stress predisposes organisms to depression and cognitive impairments, and seems to interact with metabolic homeostasis. The inflammatory response and the upregulation of proinflammatory cytokines are some of the consequences related to chronic stress. In this study, we investigated the preventive effect of chronic administration of ibuprofen, as an inhibitor of cyclooxygenases, on the cognitive and behavioral alterations and the weight gain reduction induced by simultaneous chronic restraint stress in rats.

Materials and Methods:

Male Wistar rats were subjected to chronic restraint stress and injected daily with the variable doses of ibuprofen or vehicle, for 21 consecutive days. Then, all animals were tested with the forced swim test and passive avoidance conditioning. Also, the weight of the animals was recorded before and after the interventions. Ultimately, plasma interleukin 6 (IL-6) levels were measured.

Results:

Chronic stress increased depressive-like behaviors, impaired learning, and disrupted the normal weight gain. However, the animals that received the highest dose of ibuprofen showed less depressive-like behaviors, a better avoidance memory, and a higher weight gain. However, the level of plasma IL-6 did not differ significantly between the study groups.

Conclusion:

The administration of ibuprofen prevents the cognitive and behavioral consequences of chronic stress. During the recovery, the plasma levels of IL-6 were not elevated by stress, and the IL-6 levels did not predict the behavioral performance of the stressed animals. The exact mechanisms of the protective effects of ibuprofen against chronic stress need to be further investigated.

Mental health and immunity (Review)

The immune system consists of a complex biological and psychological network designed for fighting against infections and to protect the body from pathogen factors, including the internal ones. In the past, for a long time inflammation and infectious diseases were thought to be only the result of the genetic heritage and the biological functioning of the body, when the pathogenic factors acted within the body. Studies in recent decades stressed the importance of psychological balance and mental health on the body immunity. Psychoneuroimmunology studies indicated the thoughts and emotional patterns, and the psychological dynamics are strongly interrelated with the immune response. Moreover, the immunological mechanisms not only regulates the health of the person, but they are also an important part of the individual adaptive process in the environment. In various studies, the results of each treatment modality (drug interventions and psychosocial interventions) were observed and compared in patients with mental health problems associated with immune reactions (inflammation). Psychosocial interventions suggest increased efficiency in reducing inflammation and improving immune system function.

Associations of diabetes severity and risk of depression: a population-based cohort study

OBJECTIVE

Previous literature investigating effects of diabetes complications on subsequent depression have been inconsistent. We aim to investigate associations of diabetes, complication severity, and depression.

DESIGN

This study used a nationwide database to establish an 11-year cohort comprised of people with new onset Type II diabetes mellitus (DM) aged 20 and above.

METHOD

Severity of DM was measured using the adapted Diabetes Complication Severity Index (aDCSI). Status of depression was determined by having one recorded depression diagnosis from the inpatient setting or three recorded depression diagnoses from the outpatient setting. The risk of depression was analyzed by multivariate Cox proportional models.

RESULTS

In 50,590 cases with new onset DM from years 2000 to 2011, the incidence of depression increased with severity and rates of progressions in diabetes complications regardless of demographic status, comorbidities, or medication compliance. Adjusted hazard ratios (aHR) of depression were 1.21, 1.25, 1.48 (p<0.001 for trend) in patients with a total aDCSI score of 1, 2, and > 3, respectively. Risks of depression were the highest in subgroup with the most serious progression (change of aDCSI score >2 per year) (aHR ranged between 11.6~26.0). Elevated risks of depression (aHR: 1.59~4.36) were also observed in the slower progression subgroups throughout the disease course.

CONCLUSIONS

Risks of depression were associated with multiple DM-related complications and rates of progression in severity.

Appetite changes reveal depression subgroups with distinct endocrine, metabolic, and immune states

There exists little human neuroscience research to explain why some individuals lose their appetite when they become depressed, while others eat more. Answering this question may reveal much about the various pathophysiologies underlying depression. The present study combined neuroimaging, salivary cortisol, and blood markers of inflammation and metabolism collected prior to scanning. We compared the relationships between peripheral endocrine, metabolic, and immune signaling and brain activity to food cues between depressed participants experiencing increased (N = 23) or decreased (N = 31) appetite and weight in their current depressive episode and healthy control participants (N = 42). The two depression subgroups were unmedicated and did not differ in depression severity, anxiety, anhedonia, or body mass index. Depressed participants experiencing decreased appetite had higher cortisol levels than subjects in the other two groups, and their cortisol values correlated inversely with the ventral striatal response to food cues. In contrast, depressed participants experiencing increased appetite exhibited marked immunometabolic dysregulation, with higher insulin, insulin resistance, leptin, CRP, IL-1RA, and IL-6, and lower ghrelin than subjects in other groups, and the magnitude of their insulin resistance correlated positively with the insula response to food cues. These findings provide novel evidence linking aberrations in homeostatic signaling pathways within depression subtypes to the activity of neural systems that respond to food cues and select when, what, and how much to eat. In conjunction with prior work, the present findings strongly support the existence of pathophysiologically distinct depression subtypes for which the direction of appetite change may be an easily measured behavioral marker.

The Bidirectional Relationship of Depression and Inflammation: Double Trouble

Depression represents the number one cause of disability worldwide and is often fatal. Inflammatory processes have been implicated in the pathophysiology of depression. It is now well established that dysregulation of both the innate and adaptive immune systems occur in depressed patients and hinder favorable prognosis, including antidepressant responses. In this review, we describe how the immune system regulates mood and the potential causes of the dysregulated inflammatory responses in depressed patients. However, the proportion of never-treated major depressive disorder (MDD) patients who exhibit inflammation remains to be clarified, as the heterogeneity in inflammation findings may stem in part from examining MDD patients with varied interventions. Inflammation is likely a critical disease modifier, promoting susceptibility to depression. Controlling inflammation might provide an overall therapeutic benefit, regardless of whether it is secondary to early life trauma, a more acute stress response, microbiome alterations, a genetic diathesis, or a combination of these and other factors.

Major depression accompanied with inflammation and multiple cytokines alterations: Evidences from clinical patients to macaca fascicularis and LPS-induced depressive mice model

BACKGROUND

Inflammation progress has been consistently implicated in the pathophysiology of major depressive disorder (MDD). However, the underlying mechanism of inflammation and depressive symptoms still far from being fully elucidated. In addition, studies on emotional disorders could also benefit from model of the non-human primates. To explore the difference of serum multi-cytokines levels among the MDD patients and depressed macaca fascicularis as well as LPS-treated mice, thus may find the reliable potential biomarkers for MDD.

METHODS

Serum multi-cytokines levels among MDD patients (n = 44) and depressed macaca fascicularis (n = 6) together with controls (n = 22 for human, n = 6 for macaques) were detected by the Bio-Plex cytokines panel. Then five of these serum cytokines in LPS-treated mice were measured via ELISA. Furthermore, these cytokines protein expressions were validated by western blotting in three depression-related regions of LPS-treated mice.

RESULTS

Here, we found that MDD patients displayed increased concentration of 13 proinflammatory and anti-inflammatory cytokines accompanied with one decreased cytokine in peripheral serum. Meanwhile, the naturally occurring depression (NOD) macaca fascicularis merely exhibited elevated concentration of 4 peripheral cytokines (IL-6, IL-8, MCP-1, VEGF), which were in accordance with the outcomes of MDD patients. Importantly, the serum and brain tissues of LPS-treated mice also emerged similar cytokines alterations.

CONCLUSION

In summary, our findings strengthen the evidence that cytokines were associated with the depression, and the IL-6 and VEGF may as predictive biomarkers for novel diagnostic as well as therapeutic of depression. The hypothalamus may as a key brain region involve in the inflammatory related depressive-like behaviors.

The cytokine network in the pathogenesis of major depressive disorder. Close to translation?

Major depressive disorder (MDD) is a common condition that afflicts the general population across a broad spectrum of ages and social backgrounds. MDD has been identified by the World Health Organization as a leading cause of disability worldwide. Approximately 30% of patients are poor responsive to standard of care (SOC) treatment and novel therapeutic approaches are warranted. Since chronic inflammation, as it is often observed in certain cancers, type 2 diabetes, psoriasis and chronic arthritis, are accompanied by depression, it has been suggested that immunoinflammatory processes may be involved in the pathogenesis of MDD. Cytokines are a group of glycoproteins secreted from lymphoid and non-lymphoid cells that orchestrate immune responses. It has been suggested that a dysregulated production of cytokines may be implicated in the pathogenesis and maintenance of MDD. On the basis of their functions, cytokines can be subdivided in pro-inflammatory and anti-inflammatory cytokines. Since abnormal blood and cerebrospinal fluid of both pro and anti-inflammatory cytokines are altered in MDD, it has been suggested that abnormal cytokine homeostasis may be implicated in the pathogenesis of MDD and possibly to induction of therapeutic resistance. We review current data that indicate that cytokines may represent a useful tool to identify MDD patients that may benefit from tailored immunotherapeutic approaches and may represent a potential tailored therapeutic target.

The association between overall and abdominal adiposity and depressive mood: A cross-sectional analysis in 6459 participants

OBJECTIVE

We aimed to evaluate the association between measures of adiposity with depressive mood and specific depressive symptoms.

METHODS

This study was performed in the Netherlands Epidemiology of Obesity (NEO) study, a population-based study that consists of 6671 middle-aged individuals. We examined the association between measures of overall adiposity (BMI and total body fat), and abdominal adiposity (waist circumference and visceral adipose tissue), with depressive mood severity subgroups and 30 depressive symptoms. Multinomial logistic regression was performed adjusting for potential confounding.

RESULTS

Measures of adiposity were associated with depressive mood in a graded fashion. Total body fat showed the strongest association with mild (Odds Ratio (OR): 1.59 per standard deviation, 95% Confidence Interval (95% CI): 1.41-1.80) and moderate to very severe (OR: 1.97, 95% CI: 1.59-2.44) depressive mood. Regarding individual symptoms of depressive mood, total body fat was associated with most depressive symptoms (strongest associations for hyperphagia and fatigability).

CONCLUSIONS

In the general population, overall and abdominal adiposity measures were associated with depressive mood. This association encompasses most of the depressive symptoms and appeared to be the strongest with specific ''atypical'' neurovegetative symptoms, which may be an indication of an alteration in the energy homeostasis.

Mechanistic Insights into Aspartame-induced Immune Dysregulation

Background & Objective:

Aspartame, (L-aspartyl-L-phenylalanine methyl ester) is a widely used artificial sweetener but studies raise safety concerns regarding the use of aspartame metabolites especially methanol. In this review, we aimed to provide mechanistic insights that may explain aspartame-induced immune dysregulation.

Findings:

While evidence is limited, from the available literature, possible mechanisms for immune dysfunction associated with aspartame include (1) alterations in bidirectional communication between neuro-immune-endocrine responses (2) disruption of the brain-gut-microbiota-immune axis (3) induction of oxidative stress in immune cells and organs and lastly (4) the immune-activation effect of methanol.

Conclusion:

Further studies are needed to confirm above proposed mechanisms that may explain aspartame- induce immune dysregulation.

Depressive symptoms and immune transcriptional profiles in late adolescents

BACKGROUND

Rates of depression increase and peak during late adolescence and alterations in immune processes are thought to be both a risk factor and outcome of depression. However, few studies have examined depression-immune dynamics among adolescents. Using a functional genomics approach, the current study examined whether depressive symptoms were associated with activation of a gene expression profile, characterized by upregulated expression of pro-inflammatory-related genes and downregulated expression of antiviral-related genes in a sample of older adolescents (M_age = 18.37, SD = 0.51).

METHOD

Participants (n = 87) reported on their depressive symptoms during the past week using the CES-D, and provided blood samples for genome-wide transcriptional profiling of mRNA.

RESULTS

Adolescents with clinically-significant levels of depressive symptoms (CES-D ≥ 16) exhibited upregulated expression of inflammation-related genes and downregulated expression of antiviral-related genes compared to their peers with lower levels of depressive symptoms (CES-D < 16). Bioinformatics analyses suggested that this pattern of differential gene expression was mediated by greater activity of the pro-inflammatory transcription factor, nuclear factor-kappa B (NF-κB), and reduced activity of glucocorticoid receptors (GRs) and interferon response factors (IRFs). Additional analyses implicated monocytes, B cells, and dendritic cells as primary cellular sources of the observed gene expression patterns associated with depressive symptoms.

CONCLUSION

Results are consistent with past work demonstrating links between depression and altered immunity. They provide a molecular basis for these associations and suggest that the underlying molecular signature may emerge as early as late adolescence when rates of depression tend to increase.

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

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

Quinolinic Acid and Nuclear Factor Erythroid 2-Related Factor 2 in Depression: Role in Neuroprogression

Depression is an incapacitating neuropsychiatric disorder. The serotonergic system in the brain plays an important role in the pathophysiology of depression. However, due to delayed and/or poor performance of selective serotonin reuptake inhibitors in treating depressive symptoms, the role of the serotonergic system in depression has been recently questioned further. Evidence from recent studies suggests that increased inflammation and oxidative stress may play significant roles in the pathophysiology of depression. The consequences of these factors can lead to the neuroprogression of depression, involving neurodegeneration, astrocytic apoptosis, reduced neurogenesis, reduced plasticity (neuronal and synaptic), and enhanced immunoreactivity. Specifically, increased proinflammatory cytokine levels have been shown to activate the kynurenine pathway, which causes increased production of quinolinic acid (QA, an N-Methyl-D-aspartate agonist) and decreases the synthesis of serotonin. QA exerts many deleterious effects on the brain via mechanisms including N-methyl-D-aspartate excitotoxicity, increased oxidative stress, astrocyte degeneration, and neuronal apoptosis. QA may also act directly as a pro-oxidant. Additionally, the nuclear translocation of antioxidant defense factors, such as nuclear factor (erythroid-derived 2)-like 2 (Nrf2), is downregulated in depression. Hence, in the present review, we discuss the role of QA in increasing oxidative stress in depression by modulating the nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 and thus affecting the synthesis of antioxidant enzymes.

Proteomic Studies of Psychiatric Disorders

Many diseases result from programming effects in utero. This chapter describes recent advances in proteomic studies which have improved our understanding of the underlying pathophysiological pathways in the major psychiatric disorders, resulting in the development of potential novel biomarker tests. Such tests should be based on measurement of blood-based proteins given the ease of accessibility of this medium and the known connections between the periphery and the central nervous system. Most importantly, emerging biomarker tests should be developed on lab-on-a-chip and other handheld devices to enable point-of-care use. This should help to identify individuals with psychiatric disorders much sooner than ever before, which will allow more rapid treatment options for the best possible patient outcomes.

Is the HPA Axis as Target for Depression Outdated, or Is There a New Hope?

Major depressive disorder (MDD) is a very common stress-related mental disorder that carries a huge burden for affected patients and the society. It is associated with a high mortality that derives from suicidality and the development of serious medical conditions such as heart diseases, diabetes, and stroke. Although a range of effective antidepressants are available, more than 50% of the patients do not respond to the first treatment they are prescribed and around 30% fail to respond even after several treatment attempts. The heterogeneous condition of MDD, the lack of biomarkers matching patients with the right treatments and the situation that almost all available drugs are only targeting the serotonin, norepinephrine, or dopamine signaling, without regulating other potentially dysregulated systems may explain the insufficient treatment status. The hypothalamic-pituitary-adrenal (HPA) axis is one of these other systems, there is numerous and robust evidence that it is implicated in MDD and other stress-related conditions, but up to date there is no specific drug targeting HPA axis components that is approved and no test that is routinely used in the clinical setting identifying patients for such a specific treatment. Is there still hope after these many years for a breakthrough of agents targeting the HPA axis? This review will cover tests detecting altered HPA axis function and the specific treatment options such as glucocorticoid receptor (GR) antagonists, corticotropin-releasing hormone 1 (CRH₁) receptor antagonists, tryptophan 2,3-dioxygenase (TDO) inhibitors and FK506 binding protein 5 (FKBP5) receptor antagonists.

No evidence for airborne transmission of Toxoplasma gondii in a very high prevalence area in Lancaster County

Background:

Toxoplasma gondii (T. gondii) has been associated with acute food-borne illness, chronic low-grade inflammation, neuropsychiatric conditions and reactivation of chronic latent infection in immunocompetent hosts. Primary infection with T. gondii in pregnant women can lead to congenital toxoplasmosis. In addition to well-known oral tissue-cyst or oocyst ingestion, we hypothesized that the very high prevalence of T. gondii in certain populations exposed to agricultural dust could be, in part, a consequence of airborne infection with oocysts.

Methods:

Wo collected environmental dust samples from an area with a reportedly high T. gondii seroprevalence in the Old Order Amish population, in Lancaster, Pennsylvania. Samples included: a) air filters from air-conditioning units; b) swabs of settled dust; and c) vacuum filters containing airborne field dust. Pools of the swabs and shredded sub-samples of the air filters were fed to pigs, with inoculation into mice of heart tissue from seroconverted pigs. We also investigated the presence of T. gondii DNA using PCR amplification.

Results:

Only one pig seroconverted. However, bioassay of pig heart tissue further inoculated into mice showed no evidence of T. gondii infection. Consistently, no evidence of T. gondii DNA was revealed in any sample.

Conclusions:

No evidence of airborne transmission was found in the environmental samples that were examined.

Periodontal, metabolic, and cardiovascular disease: Exploring the role of inflammation and mental health

Previous evidence connects periodontal disease, a modifiable condition affecting a majority of Americans, with metabolic and cardiovascular morbidity and mortality. This review focuses on the likely mediation of these associations by immune activation and their potential interactions with mental illness. Future longitudinal, and ideally interventional studies, should focus on reciprocal interactions and cascading effects, as well as points for effective preventative and therapeutic interventions across diagnostic domains to reduce morbidity, mortality and improve quality of life.

Anhedonia as a clinical correlate of inflammation in adolescents across psychiatric conditions

Objectives: Peripheral inflammation has been associated with multiple psychiatric disorders, particularly with depression. However, findings remain inconsistent and unreproducible, most likely due to the disorder's heterogeneity in phenotypic presentation. Therefore, in the present study, in an effort to account for inter-individual differences in symptom severity, we utilised a dimensional approach to assess the relationships between a broad panel of inflammatory cytokines and key psychiatric symptoms (i.e. depression, anhedonia, anxiety, fatigue and suicidality) in adolescents across psychiatric disorders. We hypothesised that only anhedonia (reflecting deficits of reward function) will be associated with inflammation.Methods: Participants were 54 psychotropic medication-free adolescents with diverse psychiatric conditions and 22 healthy control (HC) adolescents, aged 12-20. We measured 41 cytokines after in vitro lipopolysaccharide stimulation. Mann-Whitney U and Spearman correlation tests examined group comparison and associations, respectively, while accounting for multiple comparisons and confounds, including depression severity adolescent.Results: There were no group differences in cytokine levels. However, as hypothesised, within the psychiatric group, only anhedonia was associated with 19 cytokines, including haematopoietic growth factors, chemokines, pro-inflammatory cytokines, and anti-inflammatory cytokines.Conclusions: Our findings suggest that general inflammation may induce reward dysfunction, which plays a salient role across psychiatric conditions, rather than be specific to one categorical psychiatric disorder.

Atypical depression and non-atypical depression: Is HPA axis function a biomarker? A systematic review

BACKGROUND

The link between the abnormalities of the Hypothalamic-pituitary-adrenal (HPA) axis and depression has been one of the most consistently reported findings in psychiatry. At the same time, multiple studies have demonstrated a stronger association between the increased activation of HPA-axis and melancholic, or endogenous depression subtype. This association has not been confirmed for the atypical subtype, and some researchers have suggested that as an antinomic depressive subtype, it may be associated with the opposite type, i.e. hypo-function, of the HPA-axis, similarly to PTSD. The purpose of this systematic review is to summarise existing studies addressing the abnormalities of the HPA-axis in melancholic and/or atypical depression.

METHOD

We conducted a systematic review in the literature by searching MEDLINE, PsycINFO, OvidSP and Embase databases until June 2017. The following search items were used: "hypothalamic-pituitary-adrenal" OR "HPA" OR "cortisol" OR "corticotropin releasing hormone" OR "corticotropin releasing factor" OR "glucocorticoid*" OR "adrenocorticotropic hormone" OR "ACTH" AND "atypical depression" OR "non-atypical depression" OR "melancholic depression" OR "non-melancholic depression" OR "endogenous depression" OR "endogenomorphic depression" OR "non-endogenous depression". Search limits were set to include papers in English or German language published in peer-reviewed journals at any period. All studies were scrutinized to determine the main methodological characteristics, and particularly possible sources of bias influencing the results reported.

RESULTS

We selected 48 relevant studies. Detailed analysis of the methodologies used in the studies revealed significant variability especially regarding the samples' definition comparing the HPA axis activity of melancholic patients to atypical depression, including healthy controls. The results were subdivided into 4 sections: (1) 27 studies which compared melancholic OR endogenous depression vs. non-melancholic or non-endogenous depression or controls; (2) 9 studies which compared atypical depression or atypical traits vs. non-atypical depression or controls; (3) 7 studies which compared melancholic or endogenous and atypical depression subtypes and (4) 5 studies which used a longitudinal design, comparing the measures of HPA-axis across two or more time points. While the majority of studies did confirm the association between melancholic depression and increased post-challenge cortisol levels, the association with increases in basal cortisol and basal ACTH were less consistent. Some studies, particularly those focusing on reversed vegetative symptoms, demonstrated a decrease in the activity of the HPA axis in atypical depression compared to controls, but the majority did not distinguish it from healthy controls.

CONCLUSIONS

In conclusion, our findings indicate that there is a difference in the activity of the HPA-axis between melancholic and atypical depressive subtypes. However, these are more likely explained by hypercortisolism in melancholia; and most often normal than decreased function in atypical depression. Further research should seek to distinguish a particular subtype of depression linked to HPA-axis abnormalities, based on symptom profile, with a focus on vegetative symptoms, neuroendocrine probes, and the history of adverse childhood events. New insights into the dichotomy addressed in this review might be obtained from genetic and epigenetic studies of HPA-axis related genes in both subtypes, with an emphasis on the presence of vegetative symptoms.

How to measure glucocorticoid receptor's sensitivity in patients with stress-related psychiatric disorders

Stress is a state of derailed homeostasis and a main environmental risk factor for psychiatric diseases. Chronic or uncontrollable stress may lead to a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which is a common feature of stress-related psychiatric disorders. One of the key mechanisms underlying a disturbed HPA axis is an impaired function of the glucocorticoid receptor (GR) with an enhanced or reduced feedback sensitivity for glucocorticoids and subsequently altered concentrations of peripheral cortisol. GR function is regulated by a multiprotein complex including the different expression of the hsp90 co-chaperone FK 506 binding protein 51 (FKBP5) that may be genetically determined or acquired in response to stressful stimuli. Specific patterns of a dysregulation of the HPA axis and GR function are found in different stress-related psychiatric entities e.g. major depression, job-related exhaustion or posttraumatic stress disorder. GR challenge tests like the dexamethasone-suppression test (DST), the dexamethasone-corticotropin-releasing hormone (dex-CRH) test or most recently the analysis of the dexamethasone-induced gene expression are employed to sensitively measure HPA axis activity in these disorders. They provide information for a stratification of phenotypic similar but neurobiological diverse psychiatric disorders. In this review we present a synopsis of GR challenge tests with a focus on the application of the DST, the CRH test and the dex-CRH test as well as the dexamethasone-induced gene expression in stress-related psychiatric entities.

Metabolic and inflammatory markers: associations with individual depressive symptoms

BACKGROUND

Literature has shown that obesity, metabolic syndrome and inflammation are associated with depression, however, evidence suggests that these associations are specific to atypical depression. Which of the atypical symptoms are driving associations with obesity-related outcomes and inflammation is unknown. We evaluated associations between individual symptoms of depression (both atypical and non-atypical) and body mass index (BMI), metabolic syndrome components and inflammatory markers.

METHODS

We included 808 persons with a current diagnosis of depression participating in the Netherlands Study of Depression and Anxiety (67% female, mean age 41.6 years). Depressive symptoms were derived from the Composite International Diagnostic Interview and the Inventory of Depressive Symptomatology. Univariable and multivariable regression analyses adjusting for sex, age, educational level, depression severity, current smoking, physical activity, anti-inflammatory medication use, and statin use were performed.

RESULTS

Increased appetite was positively associated with BMI, number of metabolic syndrome components, waist circumference, C-reactive protein and tumor necrosis factor-α. Decreased appetite was negatively associated with BMI and waist circumference. Psychomotor retardation was positively associated with BMI, high-density lipoprotein cholesterol and triglycerides, and insomnia with number of metabolic syndrome components.

CONCLUSION

Increased appetite - in the context of a depressive episode - was the only symptom that was associated with both metabolic as well as inflammatory markers, and could be a key feature of an immuno-metabolic form of depression. This immuno-metabolic depression should be considered in clinical trials evaluating effectiveness of compounds targeting metabolic and inflammatory pathways or lifestyle interventions.

Mood disorders and circulating levels of inflammatory markers in a longitudinal population-based study

BACKGROUND

There has been increasing evidence that chronic low-grade inflammation is associated with mood disorders. However, the findings have been inconsistent because of heterogeneity across studies and methodological limitations. Our aim is to prospectively evaluate the bi-directional associations between inflammatory markers including interleukin (IL)-6, tumor necrosis factor (TNF)-α and high sensitivity C-reactive protein (hsCRP) with mood disorders.

METHODS

The sample consisted of 3118 participants (53.7% women; mean age: 51.0, s.d. 8.8 years), randomly selected from the general population, who underwent comprehensive somatic and psychiatric evaluations at baseline and follow-up (mean follow-up duration = 5.5 years, s.d. 0.6). Current and remitted mood disorders including bipolar and major depressive disorders (MDD) and its subtypes (atypical, melancholic, combined atypical and melancholic, and unspecified) were based on semi-structured diagnostic interviews. Inflammatory biomarkers were analyzed in fasting blood samples. Associations were tested by multiple linear and logistic regression models.

RESULTS

Current combined MDD [β = 0.29, 95% confidence interval (CI) 0.03-0.55] and current atypical MDD (β = 0.32, 95% CI 0.10-0.55) at baseline were associated with increased levels of hsCRP at follow-up. There was little evidence for inflammation markers at baseline predicting mood disorders at follow-up.

CONCLUSIONS

The prospective unidirectional association between current MDD subtype with atypical features and hsCRP levels at follow-up suggests that inflammation may be a consequence of this condition. The role of inflammation, particularly hsCRP that is critically involved in cardiovascular diseases, warrants further study. Future research that examines potential influences of medications on inflammatory processes is indicated.

Sex-related differential response to dexamethasone in endocrine and immune measures in depressed in-patients and healthy controls

Although sex differences in major depression have been reported repeatedly, the underlying mechanisms are still disputed. The rapidly changing gonadal steroid concentrations of the postpartum period or during menopause have been shown to be associated with depressive symptoms and to modulate the hypothalamic-pituitary-adrenal (HPA)-axis, which is implicated in depression. The sample comprised of 128 depressed in-patients (36.7% women) and 166 healthy controls (30.0% women). Blood was collected at baseline (at 6pm) and then 3 h as well as 21 h after ingestion of 1.5 mg dexamethasone for measurement of cortisol, ACTH and blood count. To further assess the function of the HPA-axis the dexamethasone/corticotrophin releasing hormone (Dex-CRH) test was performed in a subsample of 115 patients and 116 controls the following day. A significant interaction effect between sex, disease and ACTH concentrations over time after dexamethasone stimulation was observed, with men showing increased ACTH concentrations at baseline and after 21 h, while there was no difference after 3 h (p = .007). After separating for disease status this significant interaction effect was only observed in controls (p = .005). The cortisol response in the dex-CRH test was enhanced in female compared to male controls (p = .002). Leucocytes showed a stronger increase upon dexamethasone administration only in female compared to male controls (p = .023). These findings suggest a higher glucocorticoid receptor sensitivity following in-vivo glucocorticoid stimulation in healthy women that was absent in depressed patients. The sex-related differences in HPA-axis regulation and immune system function may contribute to the vulnerability of female sex to the development of depression.

Subtypes of depression and their overlap in a naturalistic inpatient sample of major depressive disorder

Subtyping depression is important in order to further delineate biological causes of depressive syndromes. The aim of this study was to evaluate clinical and outcome characteristics of distinct subtypes of depression and to assess proportion and features of patients fulfilling criteria for more than one subtype. Melancholic, atypical and anxious subtypes of depression were assessed in a naturalistic sample of 833 inpatients using DSM-IV specifiers based on operationalized criteria. Baseline characteristics and outcome criteria at discharge were compared between distinct subtypes and their overlap. A substantial proportion of patients (16%) were classified with more than one subtype of depression, 28% were of the distinct anxious, 7% of the distinct atypical and 5% of the distinct melancholic subtype. Distinct melancholic patients had shortest duration of episode, highest baseline depression severity, but were more often early improvers; distinct anxious patients had higher NEO-Five Factor Inventory (NEO-FFI) neuroticism scores compared with patients with unspecific subtype. Melancholic patients with overlap of anxious features had worse treatment outcome compared to distinct melancholic and distinct anxious subtype. Distinct subtypes differed in only few variables and patients with overlap of depression subtypes may have independent clinical and outcome characteristics. Studies investigating biological causes of subtypes of depression should take influence of features of other subtypes into account.

Blood-based biomarkers predicting response to antidepressants

Major depressive disorder is a common, serious and in some cases, life-threatening condition and affects approximately 350 million people globally. Although there is effective treatment available for it, more than 50% of the patients fail to respond to the first antidepressant they receive. The selection of a distinct treatment is still exclusively based on clinical judgment without incorporating lab-derived objective measures. However, there is growing evidence of biomarkers that it helps to improve diagnostic processes and treatment algorithms. Here genetic markers and blood-based biomarkers of the monoamine pathways, inflammatory pathways and the hypothalamic-pituitary-adrenal (HPA) axis are reviewed. Promising findings arise from studies investigating inflammatory pathways and immune markers that may identify patients suitable for anti-inflammatory based treatment regimes. Next, an early normalization of a disturbed HPA axis or depleted neurotrophic factors may predict stable treatment response. Genetic markers within the serotonergic system may identify patients who are vulnerable because of stressful life events, but evidence for guiding treatment regimes still is inconsistent. Therefore, there is still a great need for studies investigating and validating biomarkers for the prediction of treatment response to facilitate the treatment selection and shorten the time to remission and thus provide personalized medicine in psychiatry.

Cortisol Modulation by Ayahuasca in Patients With Treatment Resistant Depression and Healthy Controls

Major depression is a highly prevalent mood disorder, affecting about 350 million people, and around 30% of the patients are resistant to currently available antidepressant medications. Recent evidence from a randomized controlled trial (RCT) supports the rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression. The aim of this study was to explore the effect of ayahuasca on plasma cortisol and awakening salivary cortisol response, in the same group of treatment-resistant patients (MD) and in healthy volunteers (C). Subjects received a single dose of ayahuasca or placebo (dosing session), and both plasma and awakening salivary cortisol response were measured at baseline (before dosing session) and 48 h after the dosing session. Baseline assessment (D0) showed blunted awakening salivary cortisol response and hypocortisolemia in patients, with respect to healthy controls. Salivary cortisol was also measured during dosing session, and we observed higher increases for both C and MD that ingested ayahuasca than placebo. After 48 h from the dosing session with ayahuasca, patients' awakening salivary cortisol response is similar to the ones detected in controls. No significant changes in plasma cortisol levels were observed 48 h after the sessions. Therefore, these findings point to new evidence on the modulation of salivary cortisol levels as a result of an ayahuasca session, both in healthy and depressive volunteers. Considering that cortisol acts in regulation of distinct physiological pathways, emotional and cognitive processes, it is assumed to be critically involved to the etiology of depression and its regulation seems to be important for the treatment and remission of major depression, ayahuasca use as antidepressant should be further investigated. Moreover, this study highlights the importance of psychedelics in the treatment of human mental disorders.

Neuroimmune Biomarkers in Mental Illness

Exploration of neuroimmune mechanisms is vital to the understanding of the pathogenesis and pathophysiology of mental disorders. Inflammatory and immune mechanisms are increasingly understood to underpin a number of neuropsychiatric disorders, with an ever-expanding evidence base drawn from basic science to large-scale epidemiological data. Unravelling of these mechanisms should lead to biomarker discovery and potential new avenues for therapeutics that modulate immunological mechanisms. Identification of neuroimmune biomarkers is vital to improving diagnosis, stratification and treatment of mental disorders. There is an urgent clinical need for new therapeutic approaches with poor treatment response and treatment resistance a major problem for many psychiatric disorders including depression and schizophrenia. Neurodegenerative psychiatric disorders such as Alzheimer's also have clear neuroimmune underpinnings and manifest an urgent clinical need for improvements in diagnosis and research towards transformative disease-modifying treatments. This chapter provides some background on the role of the neuroimmune system in mental illness, exploring the role for biomarkers, in addition to reviewing the current state of knowledge in this exciting field. We also reflect on the inherent challenges and methodological pitfalls faced by research in this field, including the complexity of conceptualising multidimensional mental disorders and the dynamic shifting sands of the immune system.

The depressive-like behaviors of chronic unpredictable mild stress-treated mice, ameliorated by Tibetan medicine Zuotai: involvement in the hypothalamic-pituitary-adrenal (HPA) axis pathway

BACKGROUND

Zuotai, a famous Tibetan medicinal mixture containing metacinnabar, is traditionally used for the purpose of tranquilizing minds and soothing nerves. However, it still lacks substantial experimental data for it to be approved for use.

AIM

This study was designed to assess the effects of Zuotai on depressive-like symptoms in a chronic unpredictable mild stress (CUMS) mouse model, and to explore its potential mechanism, particularly the hypothalamic-pituitary-adrenal (HPA) axis pathway.

MATERIALS AND METHODS

First, Kunming mice were exposed to the CUMS procedure and simultaneously administered Zuotai or imipramine (positive control) by gavage continuously for 6 weeks. Then, depressive-like behaviors of mice in each group were tested with the sucrose preference test, forced swimming test, tail suspension test, and open field test. Meanwhile, the three key neuroendocrine hormones (corticotropin releasing hormone, adrenocorticotropic hormone and corticosterone) in HPA axis pathway, and the level of the emotion-related monoamine neurotransmitters (5-hydroxytryptamine and norepinephrine) were measured using enzyme-linked immunosorbent assay. Furthermore, total mercury in the hypothalamus and hippocampus were determined using an automatic, direct mercury analyzer.

RESULTS

Zuotai or imipramine significantly increased the body weight and the sucrose preference ratio in sucrose preference test, and dramatically improved motor activity in forced swimming test, tail suspension test, and open field test in CUMS mice. Zuotai or imipramine remarkably decreased levels of corticotropin-releasing hormone, adrenocorticotropic hormone, and corticosterone in the HPA axis, and increased levels of 5-hydroxytryptamine and norepinephrine in the serum in CUMS mice. However, a small amount of mercury was deposited in the hypothalamus and hippocampus in Zuotai-treated mice, which may pose a potential risk to the central nervous system.

CONCLUSION

Zuotai has a strong ability to ameliorate depressive-like behaviors in CUMS-treated mice through inhibition of the HPA axis and upregulation of monoamine neurotransmitters. These findings provide new insight into the pharmacological effect of Zuotai on depression.

Genetic Association of Major Depression With Atypical Features and Obesity-Related Immunometabolic Dysregulations

IMPORTANCE

The association between major depressive disorder (MDD) and obesity may stem from shared immunometabolic mechanisms particularly evident in MDD with atypical features, characterized by increased appetite and/or weight (A/W) during an active episode.

OBJECTIVE

To determine whether subgroups of patients with MDD stratified according to the A/W criterion had a different degree of genetic overlap with obesity-related traits (body mass index [BMI] and levels of C-reactive protein [CRP] and leptin).

DESIGN, SETTING, AND PATIENTS

This multicenter study assembled genome-wide genotypic and phenotypic measures from 14 data sets of the Psychiatric Genomics Consortium. Data sets were drawn from case-control, cohort, and population-based studies, including 26 628 participants with established psychiatric diagnoses and genome-wide genotype data. Data on BMI were available for 15 237 participants. Data were retrieved and analyzed from September 28, 2015, through May 20, 2017.

MAIN OUTCOMES AND MEASURES

Lifetime DSM-IV MDD was diagnosed using structured diagnostic instruments. Patients with MDD were stratified into subgroups according to change in the DSM-IV A/W symptoms as decreased or increased.

RESULTS

Data included 11 837 participants with MDD and 14 791 control individuals, for a total of 26 628 participants (59.1% female and 40.9% male). Among participants with MDD, 5347 (45.2%) were classified in the decreased A/W and 1871 (15.8%) in the increased A/W subgroups. Common genetic variants explained approximately 10% of the heritability in the 2 subgroups. The increased A/W subgroup showed a strong and positive genetic correlation (SE) with BMI (0.53 [0.15]; P = 6.3 × 10-4), whereas the decreased A/W subgroup showed an inverse correlation (-0.28 [0.14]; P = .06). Furthermore, the decreased A/W subgroup had a higher polygenic risk for increased BMI (odds ratio [OR], 1.18; 95% CI, 1.12-1.25; P = 1.6 × 10-10) and levels of CRP (OR, 1.08; 95% CI, 1.02-1.13; P = 7.3 × 10-3) and leptin (OR, 1.09; 95% CI, 1.06-1.12; P = 1.7 × 10-3).

CONCLUSIONS AND RELEVANCE

The phenotypic associations between atypical depressive symptoms and obesity-related traits may arise from shared pathophysiologic mechanisms in patients with MDD. Development of treatments effectively targeting immunometabolic dysregulations may benefit patients with depression and obesity, both syndromes with important disability.