Circulating cytokine concentrations are not associated with major depressive disorder in a community-based cohort

Associations between insomnia symptoms and inflammatory cytokines in adolescents with first-episode and recurrent major depressive disorder

BACKGROUND

Insomnia symptoms are often associated with increased levels of inflammatory biomarkers. However, such associations have not been adequately explored in adolescents with major depressive disorder (MDD). This study aimed to examine the associations between insomnia symptoms with inflammatory cytokines in adolescents with first-episode and recurrent MDD.

METHODS

From January to December 2021, this study included 164 adolescents with MDD and 76 healthy controls (HCs). The Center for Epidemiological Studies Depression Scale (CES-D) and the Insomnia Severity Index Scale (ISI) were used to assess depressive and insomnia symptoms, respectively. Also, plasma levels of interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-17 A and tumor necrosis factor-α (TNF-α) were measured.

RESULTS

The prevalence of mild, moderate and severe insomnia in adolescents with MDD was 40.24 %, 36.59 % and 6.71 %, respectively. The patients had higher levels of IL-1β, IL-6 and TNF-α than HCs (all p < 0.05). ISI score was positively correlated with CES-D score and levels of IL-1β, IL-6 and TNF-α in first-episode patients but not in recurrent patients. A further multivariate stepwise linear regression analysis showed that ISI score was independently associated with CES-D score (beta = 0.523, t = 5.833, p < 0.001) and TNF-α levels (beta = 0.254, t = 2.832, p = 0.006).

LIMITATIONS

The cross-sectional design leads to failure to make causal inferences.

CONCLUSION

Insomnia symptoms are common in adolescents with MDD and associated with elevated levels of inflammatory cytokines in first-episode patients. The findings suggest that inflammatory cytokines may relate to the pathogenesis of insomnia symptoms in adolescents with MDD, but further longitudinal studies are needed to explore the causal association between insomnia symptoms and inflammatory cytokines in MDD.

Altered serum TNF-α and MCP-4 levels are associated with the pathophysiology of major depressive disorder: A case-control study results

BACKGROUND

Major Depressive Disorder (MDD) is a debilitating mental health condition with complex etiology, and recent research has focused on pro-inflammatory cytokines and chemokines as potential contributors to its pathogenesis. However, studies investigating the roles of TNF-α and MCP-4 in MDD within the Bangladeshi population are scarce. This study aimed to assess the association between serum TNF-α and MCP-4 levels and the severity of MDD, exploring their potential as risk indicators for MDD development.

METHODS

This case-control study enrolled 58 MDD patients from Bangabandhu Sheikh Mujib Medical University (BSMMU) Hospital, Dhaka, Bangladesh, alongside 30 age, sex, and BMI-matched healthy controls. MDD diagnosis followed DSM-5 criteria and disease severity using the 17-item Hamilton Depression Rating Scale (Ham-D). We measured serum TNF-α and MCP-4 levels using ELISA assays according to the supplied protocols.

RESULTS

The study revealed significantly elevated serum TNF-α levels in MDD patients (47±6.6 pg/ml, mean±SEM) compared to controls (28.06±1.07 pg/ml). These increased TNF-α levels positively correlated with Ham-D scores (Pearson's r = 0.300, p = 0.038), suggesting a potential association between peripheral TNF-α levels and MDD pathology. Additionally, MDD patients exhibited significantly higher serum MCP-4 levels (70.49±6.45 pg/ml) than controls (40.21±4.08 pg/ml). However, serum MCP-4 levels showed a significant negative correlation (r = -0.270, P = 0.048) with Ham-D scores in MDD patients, indicating a more complex role for MCP-4 in MDD pathogenesis.

CONCLUSION

This study highlights that Bangladeshi MDD patients exhibit heightened inflammatory and immune responses compared to controls, supporting the cytokine hypothesis in MDD pathogenesis. Serum TNF-α, but not MCP-4, shows promise as a potential biomarker for assessing the risk of MDD development, which could aid in early detection. Future investigations involving larger populations and longitudinal studies are essential to confirm the utility of these cytokines as biomarkers for MDD.

Major depressive disorder (mdd): emerging immune targets at preclinical level

BACKGROUND

Major depressive disorder is a mental health disorder that is characterized by a persistently low mood and loss of interest. MDD is affecting over 3.8% of the global population as a major health problem. Its etiology is complex, and involves the interaction between a number of factors, including genetic predisposition and the presence of environmental stresses.

AREAS COVERED

The role of the immune and inflammatory systems in depression has been gaining interest, with evidence suggesting the potential involvement of pro-inflammatory molecules like TNF, interleukins, prostaglandins, and other cytokines, among others, has been put forth. Along with this, the potential of agents, from NSAIDs to antibiotics, are being evaluated in therapy for depression. The current review will discuss emerging immune targets at the preclinical level.

EXPERT OPINION

With increasing evidence to show that immune and inflammatory mediators are implicated in MDD, increasing research toward their potential as drug targets is encouraged. At the same time, agents acting on these mediators and possessing anti-inflammatory potential are also being evaluated as future therapeutic options for MDD, and increasing focus toward non-conventional drugs which can act through these mechanisms is important as regards the future prospects of the use of anti-inflammatory agents in depression.

Inflammatory Cytokines, but Not Dietary Patterns, Are Related to Somatic Symptoms of Depression in a Sample of Women

Background

Depression is a heterogenous disorder with both cognitive and somatic symptom dimensions that may differentially relate to systemic inflammation. Diet, which has the potential to modulate both inflammation levels and mood, is yet to be studied within the context of individual depression dimensions. This study examined the associations between inflammatory cytokines and dietary patterns with depressive symptom dimension profiles among a sample of women recruited in a non-clinical setting.

Methods

Inflammatory cytokines (IL-6 and TNF-α), inflammatory diet (Diet Inflammatory Index; DII), and depressive symptoms (Beck Depression Inventory-II; BDI-II) were measured in 136 females (M age = 22.01 ± 4.02, range 18-59 years). Multiple linear regressions were used to investigate the relationships between inflammatory cytokines and diet with self-reported cognitive, somatic, and total depressive symptoms, adjusting for demographic factors.

Results

Findings showed that increased somatic dimension scores were positively associated with IL-6 (ß = 0.273, p = 0.002) and TNF-α (ß = 0.215, p = 0.017), but not inflammatory diet (p = 0.300). Total BDI-II scores were only positively associated with IL-6 (ß = 0.221, p = 0.012), and cognitive dimension scores were not associated with any inflammation measures.

Conclusions

These findings contribute to existing evidence that inflammatory cytokines are associated with the somatic symptoms of depression. Inflammatory diet index was not associated with depression measures.

Increased serum resistin but not G-CSF levels are associated in the pathophysiology of major depressive disorder: Findings from a case-control study

Background

Many studies have predicted major depressive disorder (MDD) as the leading cause of global health by 2030 due to its high prevalence, disability, and illness. However, the actual pathophysiological mechanism behind depression is unknown. Scientists consider alterations in cytokines might be tools for understanding the pathogenesis and treatment of MDD. Several past studies on several inflammatory cytokine expressions in MDD reveal that an inflammatory process is activated, although the precise causes of that changes in cytokine levels are unclear. Therefore, we aimed to investigate resistin and G-CSF in MDD patients and controls to explore their role in the pathogenesis and development of depression.

Methods

We included 220 participants in this study. Among them, 108 MDD patients and 112 age-sex matched healthy control (HCs). We used DSM-5 to evaluate study participants. Also, we applied the Ham-D rating scale to assess the severity of patients. Serum resistin and G-CSF levels were measured using ELISA kits (BosterBio, USA).

Results

The present study observed increased serum resistin levels in MDD patients compared to HCs (13.82 ± 1.24ng/mL and 6.35 ± 0.51ng/mL, p <0.001). However, we did not find such changes for serum G-CSF levels between the groups. Ham-D scores showed a significant correlation with serum resistin levels but not G-CSF levels in the patient group. Furthermore, ROC analysis showed a fairly predictive performance of serum resistin levels in major depression (AUC = 0.746).

Conclusion

The present study findings suggest higher serum resistin levels are associated with the pathophysiology of MDD. This elevated serum resistin level may serve as an early risk assessment indicator for MDD. However, the role of serum G-CSF in the development of MDD is still unclear despite its neuroprotective and anti-inflammatory effects.

IL-6 and hsCRP in Somatic Symptom Disorders and related disorders

Interleukin 6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) are biomarkers of systemic low-grade inflammation (SLI) in depression and anxiety. The question if SLI in those conditions is related to comorbid chronic medical conditions has not been resolved. DSM-5 Somatic symptom disorders and related disorders (SSRD) are conditions with serious distress related to physical symptoms as main criterion. They can occur in patients with medically unexplained symptoms (MUS) and in patients with known comorbid chronic medical conditions. Often, comorbid depression and anxiety are present. SSRDs offer the opportunity to explore the role of SLI in relation to mental distress, including trauma, MUS, chronic medical conditions and comorbid mental disorder.

AIM

We hypothesized that increased IL-6 and hsCRP may be directly linked to SLI in SSRD, and that comorbid chronic medical conditions, childhood trauma, current stress and comorbid depression and anxiety may be risk factors that account for some of the variance of SLI in SSRD.

METHODS

We explored these relationships in a large sample of 241 consecutive outpatients with SSRD.

RESULTS

Mean hsCRP level was 3.66 ​mg/l, and mean IL-6 level was 3.58 ​pg/ml. IL-6 and hsCRP levels were associated with each other: τ ​= ​0.249, p ​< ​.001; a medium size correlation. Comorbid chronic medical conditions, adverse childhood events other than sexual trauma, and current stress levels were not associated with IL-6 or hsCRP levels.

CONCLUSION

IL-6 and hsCRP are elevated in SSRD, indicating SLI in SSRD independently of comorbid chronic medical conditions. In clinical research, elevated IL-6 and hsCRP can be used as biomarkers of SLI and can indicate risk for childhood sexual abuse in SSRD. Elevated hsCRP may be a biomarker indicating risk for comorbid depression or high pain levels in SSRD as well.

Higher levels of serum IL-1β and TNF-α are associated with an increased probability of major depressive disorder

Major depressive disorder (MDD) is a debilitating psychiatric disease. The dysregulated cytokines in depression are assumed due to the hyperactivation of the immune system. Here we aimed to evaluate the serum interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in MDD. This study recruited 87 MDD patients and 87 age and sex-matched healthy controls (HCs). The increased levels of serum IL-1β and TNF-α were observed among MDD patients. These higher levels of peripheral markers were positively correlated with the severity of depression. Therefore, the elevated levels of serum IL-1β and TNF-α might be used as risk assessment indicators for depression.

Vitamin E for the management of major depressive disorder: possible role of the anti-inflammatory and antioxidant systems

OBJECTIVES

Vitamin E has various functions in humans, including antioxidant, anti-inflammatory, anti-cancer, and anti-atherogenic actions, as well as direct effects on enzymatic activities and modulation of gene transcription. In addition to these functions, vitamin E is also important for the central nervous system, and its role in the prevention and/or treatment of some neurological diseases has been suggested. In particular, the role of vitamin E in the modulation of major depressive disorder (MDD) is an issue that has emerged in recent studies. Many factors have been implicated in the pathophysiology of this disorder, including inflammation, oxidative, and nitrosative stress.

METHODS

This narrative review discusses the involvement of inflammation, oxidative, and nitrosative stress in the pathophysiology of MDD and presents clinical and preclinical studies that correlate vitamin E with this psychiatric disorder.

RESULTS

We gathered evidence from clinical studies that demonstrated the relationship between low vitamin E status and MDD symptoms. Vitamin E has been reported to exert a beneficial influence on the oxidative and inflammatory status of individuals, factors that may account for the attenuation of depressive symptoms. Preclinical studies have reinforced the antidepressant-like response of vitamin E, and the mechanisms underlying its effect seem to be related to the modulation of oxidative stress and neuroinflammation.

CONCLUSION

We suggest that vitamin E has potential to be used as an adjuvant for the management of MDD, but more studies are clearly needed to ascertain the efficacy of vitamin E for alleviating depressive symptoms.

The Role of Chemokines in the Pathophysiology of Major Depressive Disorder

Major depressive disorder (MDD) is a debilitating condition, whose high prevalence and multisymptomatic nature set its standing as a leading contributor to global disability. To better understand this psychiatric disease, various pathophysiological mechanisms have been proposed, including changes in monoaminergic neurotransmission, imbalance of excitatory and inhibitory signaling in the brain, hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, and abnormalities in normal neurogenesis. While previous findings led to a deeper understanding of the disease, the pathogenesis of MDD has not yet been elucidated. Accumulating evidence has confirmed the association between chronic inflammation and MDD, which is manifested by increased levels of the C-reactive protein, as well as pro-inflammatory cytokines, such as Interleukin 1 beta, Interleukin 6, and the Tumor necrosis factor alpha. Furthermore, recent findings have implicated a related family of cytokines with chemotactic properties, known collectively as chemokines, in many neuroimmune processes relevant to psychiatric disorders. Chemokines are small (8-12 kDa) chemotactic cytokines, which are known to play roles in direct chemotaxis induction, leukocyte and macrophage migration, and inflammatory response propagation. The inflammatory chemokines possess the ability to induce migration of immune cells to the infection site, whereas their homeostatic chemokine counterparts are responsible for recruiting cells for their repair and maintenance. To further support the role of chemokines as central elements to healthy bodily function, recent studies suggest that these proteins demonstrate novel, brain-specific mechanisms including the modulation of neuroendocrine functions, chemotaxis, cell adhesion, and neuroinflammation. Elevated levels of chemokines in patient-derived serum have been detected in individuals diagnosed with major depressive disorder, bipolar disorder, and schizophrenia. Furthermore, despite the considerable heterogeneity of experimental samples and methodologies, existing biomarker studies have clearly demonstrated the important role of chemokines in the pathophysiology of psychiatric disorders. The purpose of this review is to summarize the data from contemporary experimental and clinical studies, and to evaluate available evidence for the role of chemokines in the central nervous system (CNS) under physiological and pathophysiological conditions. In light of recent results, chemokines could be considered as possible peripheral markers of psychiatric disorders, and/or targets for treating depressive disorders.

Inflammatory profiles of severe treatment-resistant depression

BACKGROUND

Treatment-resistant depression (TRD) contributes substantially to the burden of mood disorders and is undoubtedly an important subpopulation in whom there are clear unmet treatment needs. Despite a paucity of research focusing specifically on TRD, recent studies indicate that inflammatory activity may be particularly elevated in these patients.

METHODS

36 patients with TRD were investigated longitudinally before and after undertaking a specialist inpatient treatment program. 27 inflammatory proteins were compared between patients and a matched sample of non-depressed controls, as well as between treatment responders and non-responders. Treatment outcomes were calculated from depression severity scores before and after admission, and at a long-term follow-up 3-12 months after discharge.

RESULTS

TRD patients had higher levels of numerous inflammatory proteins than controls, and elevated interleukins 6 and 8, tumour necrosis factor, c-reactive protein and macrophage inflammatory protein-1 were associated with poorer treatment outcomes. A separate set of proteins (either anti-inflammatory in nature or attenuated at baseline) showed increases during treatment, regardless of clinical response. Participants with the greatest elevations in inflammation tended to be older, more cognitively impaired and more treatment-resistant at baseline.

LIMITATIONS

The small sample and large number of comparisons examined in this study must be taken into account when interpreting these results.

CONCLUSIONS

However, this study provides empirical support for theories that more severe, chronic or treatment-resistant depressive disorders are associated with dysregulated inflammatory activity. If a predictor or predictors of response in TRD are established, improved and targeted care might be more reliably provided to this vulnerable population.

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.

Chemokines in depression in health and in inflammatory illness: a systematic review and meta-analysis

Inflammatory illness is associated with depression. Preclinical work has shown that chemokines are linked with peripheral-central crosstalk and may be important in mediating depressive behaviours. We sought to establish what evidence exists that differences in blood or cerebrospinal fluid chemokine concentration discriminate between individuals with depression and those without. Following PRISMA guidelines, we systematically searched Embase, PsycINFO and Medline databases. We included participants with physical illness for subgroup analysis, and excluded participants with comorbid psychiatric diagnoses. Seventy-three studies met the inclusion criteria for the meta-analysis. Individuals with depression had higher levels of blood CXCL4 and CXCL7 and lower levels of blood CCL4. Sensitivity analysis of studies with only physically healthy participants identified higher blood levels of CCL2, CCL3, CCL11, CXCL7 and CXCL8 and lower blood levels of CCL4. All other chemokines examined did not reveal significant differences (blood CCL5, CCL7, CXCL9, CXCL10 and cerebrospinal fluid CXCL8 and CXCL10). Analysis of the clinical utility of the effect size of plasma CXCL8 in healthy individuals found a negative predictive value 93.5%, given the population prevalence of depression of 10%. Overall, our meta-analysis finds evidence linking abnormalities of blood chemokines with depression in humans. Furthermore, we have demonstrated the possibility of classifying individuals with depression based on their inflammatory biomarker profile. Future research should explore putative mechanisms underlying this association, attempt to replicate existing findings in larger populations and aim to develop new diagnostic and therapeutic strategies.

Antidepressant effects of Kai-Xin-San in fluoxetine-resistant depression rats

This study aimed to investigate the antidepressant effect and the mechanism of action of Kai-Xin-San (KXS) in fluoxetine-resistant depressive (FRD) rats. Two hundred male Wistar rats weighing 200±10 g were exposed to chronic and unpredictable mild stresses (CUMS) for 4 weeks and given fluoxetine treatment simultaneously. The rats that did not show significant improvement in behavioral indexes were chosen as the FRD model rats. These rats were randomly divided into four groups: FRD model control; oral fluoxetine and aspirin; oral KXS at a dose of 338 mg·kg-1·day-1; and oral KXS at a dose of 676 mg·kg-1·day-1. Rats continued to be exposed to CUMS and underwent treatment once a day for 3 weeks, then cytokine (COX-2, IFN-γ, IL-1β, IL-2, IL-4, IL-6, IL-10, TGF-β, and TNF-α) levels in the hippocampus and serum, and organ coefficients were measured. Both doses of KXS improved the crossing and rearing frequencies, sucrose-preference index, and body weight in FRD rats. KXS at a dose of 338 mg·kg-1·day-1reduced COX-2, IL-2, IL-6, TNF-α levels, increased IL-10 level in the hippocampus, and reduced IL-2 and TNF-α levels in serum. KXS at a dose of 676 mg·kg-1·day-1reduced TNF-α level in the hippocampus, reduced IL-2 and TNF-α levels in serum, and increased IFN-γ and IL-10 levels in the hippocampus and serum. There were no significant differences in organ-coefficients of the spleen among and between groups. The results suggested that oral administration of KXS in FRD rats was effective in improving behavior disorders by influencing various inflammatory pathways.

Altered serum levels of TNF-α, IL-6, and IL-18 in depressive disorder patients

OBJECTIVE

Depressive disorder is associated with abnormal changes in cytokines levels. This study aimed to assess serum concentrations of tumor necrosis factor (TNF) α, interleukin (IL) 6, and IL-18 in depressive patients. The correlations between these three cytokine concentrations and the patients' clinical characteristics were also assessed.

METHODS

Serum TNF-α, IL-6, and IL-18 concentrations were assessed using enzyme-linked immunosorbent assay from 64 depressive patients and 80 healthy control subjects. Depressive symptoms of patients were assessed using Hamilton Depression Scale-17.

RESULTS

Depressive patients had increased serum TNF-α and IL-6 concentrations but decreased IL-18 concentrations than controls. TNF-α and IL-6 concentrations were significantly positively associated with Hamilton Depression Scale-17 scores in depressive patients.

CONCLUSION

These findings provided additional evidence that altered TNF-α, IL-6, and IL-18 activities may contribute to the pathophysiology of depressive disorder.

Peripheral Immune Alterations in Major Depression: The Role of Subtypes and Pathogenetic Characteristics

Depression has been associated with peripheral inflammatory processes and alterations in cellular immunity. Growing evidence suggests that immunological alterations may neither be necessary nor sufficient to induce depression in general, but seem to be associated with specific features. Using baseline data from the Outcome of Psychological Interventions in Depression trial, this exploratory study examines associations between depression subtypes and pathogenetic characteristics (i.e., melancholic vs non-melancholic depression, chronic vs non-chronic depression, age of onset, cognitive-affective and somatic symptom dimensions) with plasma levels of C-reactive protein (CRP), interleukin (IL)-6, IL-10, and numbers of leukocyte subpopulations in 98 patients with major depression (MD) and 30 age and sex-matched controls. Patients with MD exhibited higher CRP levels, higher neutrophil and monocyte counts, lower IL-10 levels, and an increased neutrophil to lymphocyte ratio (NLR) than controls. Patient with later age of onset had higher levels of two inflammatory markers (CRP, NLR) and lower cytotoxic T cell counts after adjusting for sociodemographics, lifestyle factors, and antidepressants. Furthermore, lower anti-inflammatory IL-10 levels were related to more severe somatic depressive symptoms. These results confirm and extend previous findings suggesting that increased levels of CRP are associated with a later onset of depression and demonstrate that also NLR as a subclinical inflammatory marker is related to a later onset of depression.

A meta-analysis of blood cytokine network alterations in psychiatric patients: comparisons between schizophrenia, bipolar disorder and depression

Schizophrenia, bipolar disorder and major depressive disorder (MDD) have all been associated with aberrant blood cytokine levels; however, neither the pattern of cytokine alterations nor the impact of clinical status have been compared across disorders. We performed a meta-analysis of blood cytokines in acutely and chronically ill patients with these major psychiatric disorders. Articles were identified by searching the PubMed, PsycInfo and Web of Science, and the reference lists of these studies. Sixty-eight studies met the inclusion criteria (40 schizophrenia, 10 bipolar disorder and 18 MDD) for acutely ill patients. Forty-six studies met the inclusion criteria (18 schizophrenia, 16 bipolar disorder and 12 MDD) for chronically ill patients. Levels of two cytokines (interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α)), one soluble cytokine receptor (sIL-2R), and one cytokine receptor antagonist (IL-1RA) were significantly increased in acutely ill patients with schizophrenia, bipolar mania and MDD compared with controls (P<0.01). Following treatment of the acute illness, IL-6 levels significantly decreased in both schizophrenia and MDD (P<0.01); sIL-2R levels increased in schizophrenia; and IL-1RA levels in bipolar mania decreased. In chronically ill patients, the levels of IL-6 were significantly increased in schizophrenia, euthymic (but not depressed) bipolar disorder and MDD compared with controls (P<0.01). The levels of IL-1β and sIL-2R were significantly increased in both chronic schizophrenia and euthymic bipolar disorder. Overall, there were similarities in the pattern of cytokine alterations in schizophrenia, bipolar disorder and MDD during acute and chronic phases of illness, raising the possibility of common underlying pathways for immune dysfunction. Effects of treatment on cytokines were more robust for schizophrenia and MDD, but were more frequently studied than for acute mania. These findings have important implications for our understanding of the pathophysiology and treatment of major psychiatric disorders.

Evaluation of periodontitis in hospital outpatients with major depressive disorder. A focus on gingival and circulating cytokines

An imbalance in stimulated cytokine production is associated with the etiopathogenesis of numerous diseases such as major depressive disorder (MDD) and periodontal disease. Increased cytokine levels have been reported in the gingival crevicular fluid (GCF) of patients with MDD. Thirty-six outpatients with MDD participated in this study. Each outpatient was age-matched (± 3 years) with a healthy control (n=36). The patients were controlled for race and smoking habits. Unstimulated and stimulated interleukin 6 (IL-6), interleukin 1β (IL-1β), and interferon-γ (INF-γ) production in whole blood culture (WBC) and IL-6 and IL-1β levels in the GCF were evaluated. Circulating levels of IL-6 and IL-1β (unstimulated) as well as GCF IL-1β were modestly lower in MDD patients, compared to the levels in age-matched controls (Mann-Whitney, p=0.002, 0.0075, ANCOVA, p=0.025, respectively). In the unstimulated group, there was no correlation between the levels of circulating IL-6 and GCF IL-6 (r=0.07, p=0.67), and between the levels of circulating IL-1β and the IL-1β level in the CGF (r=-0.08, p=0.63). In the LPS stimulation group, there was no correlation between the levels of circulating levels of IL-6 and GCF IL-6 (r=0. 02, p=0.91) or between the circulating IL-1β and GCF IL-1β (r=0.13, p=0.42). We observed modest immunosuppression in MDD patients (evaluated by no stimulation whole blood culture [WBC]), especially in patients with melancholic depression, chronic depression, and severe depression.

Serum cytokines and anxiety in adolescent depression patients: Gender effect

The present study compares the serum cytokine levels between adolescent depression patients and healthy controls and assesses correlation between depression, anxiety scores and serum levels of eight cytokines. Study also checked the variation in serum levels with medication status (medication free/naïve vs. patients on medication). Following clinical and psychometric assessment of 77 adolescent (aged 13-18 years) depression patients (49 males and 28 females; 56 medication free/naïve) and 54 healthy controls (25 males, 29 females), eight cytokines (IL-1β, IL-2, IL-6, IL-10, TNF-α, IFN-γ, TGF-β1 and IL-17A {denoted IL-17 throughout}) were measured in serum using ELISA. Depressed adolescents had significantly high levels of IL-2 (p<0.001) and IL-6 (p=0.03) as compared to controls. The female population skewed the result of one cytokine (IL-6) in patients. Anxiety scores showed positive correlation (only in female patients) with IL-1β, IL-10 and negative correlation with TGF-β1 and IL-17. The gender effect in relationship between anxiety and cytokines was not straightforward. On comparing study groups on the medication/naïve status, IL-2 and TGF-β1 showed significant difference between the groups (p<0.001, p=0.007 higher in medicated). Depression in adolescents was associated with elevation of proinflammatory serum cytokines with a gender bias for females. Anxiety scores correlated negatively with TGF-β1 and IL-17.

Danzhi Xiaoyao San ameliorates depressive-like behavior by shifting toward serotonin via the downregulation of hippocampal indoleamine 2,3-dioxygenase

ETHNOPHARMACOLOGICAL RELEVANCE

Danzhi Xiaoyao San (DXS) is a canonical Chinese medicine formula from Principles of Internal Medicine, which was written during the Ming dynasty. This formula is approved and commercialized for use in the prevention and treatment of affective disorders. This study is aimed to investigate the hypothesis that DXS treats depressive-like behavior by shifting the balance of the kynurenine (Kyn)/serotonin (5-HT) pathway toward the 5-HT pathway through the downregulation of hippocampal indoleamine 2,3-dioxygenase (IDO).

MATERIALS AND METHODS

Chemical fingerprints of gardenoside, paeoniflorin, ferulic acid, paeonol, and ligustilide in standard extraction were used as the material bases of DXS. Rats with depressive-like behavior induced by chronic unpredictable mild stress (CUMS) were randomly divided into four groups, namely the control, model, DXS, and fluoxetine groups. Cytokines, IDO, and tryptophan (Trp) catabolites were analyzed by enzyme-linked immunosorbent assay, western blot, and liquid chromatography-electrospray ionization tandem mass spectrometry, respectively.

RESULTS

DXS significantly increased crossing grid numbers, sucrose consumption, and body weight. This treatment significantly decreased the serum levels of tumor necrosis factor-α and interleukin 6 (IL-6). However, DXS elicited no significant effects on IL-1β, IL-2, and interferon γ. DXS downregulated the activity of IDO and subsequent production of Kyn in the hippocampus. This treatment upregulated the hippocampal contents of Trp and 5-HT but did not influence 5-HT turnover.

CONCLUSIONS

DXS exhibited antidepressant-like effects on rats exposed to CUMS. DXS reduced IDO activity to shift the balance of the Kyn/5-HT pathway toward the 5-HT pathway.

Elevated IL-6 levels in patients with atypical depression but not in patients with typical depression

Elevated levels of the proinflammatory cytokine Interleukin-6 (IL-6) are among the most consistent findings in patients with major depressive disorder (MDD). Additionally, some evidence suggests that elevated cytokine levels in patients with major depression are responsible for the development of metabolic syndrome in patients suffering from MDD. Therefore, the aim of the study was to examine the concentrations of IL-6 in specific subtypes of MDD and to investigate their relationship to metabolic factors. Twenty-four patients with typical (24) and atypical (eight) major depression according to DSM-IV criteria were studied and compared to 24 normal controls. Blood samples were collected during a stepwise glucose-clamp procedure, and IL-6 concentrations were measured by high sensitivity ELISA. IL-6 levels were elevated in patients suffering from atypical depression but not in patients with typical depression, compared to normal controls. IL-6 correlated significantly with HbA1c, insulin, waist girth, BMI, number of alcoholic drinks per week and C-reactive protein. Our data indicate that high concentrations of IL-6 during the glucose clamp may be limited to the atypical subgroup of patients with MDD.

Soyo-san reduces depressive-like behavior and proinflammatory cytokines in ovariectomized female rats

Background

Soyo-san is a traditional oriental medicinal formula, a mixture of 9 crude drugs, and it has been clinically used for treating mild depressive disorders. The role of pro- and anti-inflammatory cytokines in psychiatric disorders has been the focus of great research attention in recent years. In the present study, we detected the antidepressant effect of soyo-san in the ovariectomized and repeated stressed female rats.

Methods

This study was designed to evaluate the antidepressant-like effect of soyo-san on the forced swimming test (FST). The rats were randomly divided into the following groups: the nonoperated and nonstressed group (non-op), the nonoperated and stressed group (non-op + ST), the ovariectomized and stress group (OVX) and sham operated and stressed group (sham), the ovariectomized and stressed group (OVX + ST), the ovariectomized, stressed and soyo-san 100 mg/kg treated group (SOY100) and the ovariectomized, stressed and soyo-san 400 mg/kg treated group (SOY400). The rats were exposed to immobilization stress (IMO) for 14day (2 h/14day), and soyo-san (100 mg/kg and 400 mg/kg) was administrated during the same time. In the same animals, the levels of corticosterone and interleukin-1-beta (IL-1β) were examined in the serum. Also, the change of IL-1β expression in brain regions was examined after behavior test.

Results

In the FST, the lower dose (100 mg/kg) of extract was effective in reducing immobility, along with an increase in swimming time. The serum levels of corticosterone and IL-1β in the SOY groups were significantly lower than those in the control group. In the brain, the expression of IL-1β positive neurons in the control group were significantly increased in the paraventricular nucleus (PVN) and hippocampus compared to the non-op. However, soyo-san groups significantly reduced the IL-1β-ir neurons in the PVN and hippocampal regions compared to the control.

Conclusion

The present results demonstrated that soyo-san effectively reduced behavioral and patho-physiological depression-like responses. Trial registration: Our results suggest that soyo-san may be useful for immune regulator in repeated stress-induced ovariectomized female rats.

Elevated specific peripheral cytokines found in major depressive disorder patients with childhood trauma exposure: a cytokine antibody array analysis

Taking into consideration the previous evidence of revealing the relationship of early life adversity, major depressive disorder (MDD), and stress-linked immunological changes, we recruited 22 MDD patients with childhood trauma exposures (CTE), 21 MDD patients without CTE, and 22 healthy controls without CTE, and then utilized a novel cytokine antibody array methodology to detect potential biomarkers underlying MDD in 120 peripheral cytokines and to evaluate the effect of CTE on cytokine changes in MDD patients. Although 13 cytokines were identified with highly significant differences in expressions between MDD patients and normal controls, this relationship was significantly attenuated and no longer significant after consideration of the effect of CTE in MDD patients. Depressed individuals with CTE (TD patients) were more likely to have higher peripheral levels of those cytokines. Severity of depression was associated with plasma levels of certain increased cytokines; meanwhile, the increased cytokines led to a proper separation of TD patients from normal controls during clustering analyses. Our research outcomes add great strength to the relationship between depression and cytokine changes and suggest that childhood trauma may play a vital role in the co-appearance of cytokine changes and depression.

Research review: the role of cytokines in depression in adolescents: a systematic review

BACKGROUND

While cytokines have been implicated in the pathophysiology of depression in adults, the potential role in younger age groups such as adolescents is less clear. This article therefore reviews the literature (a) to explore the relationship between cytokines and depression in adolescents, and (b) to examine how cytokines may be related to adolescent depression in the context of other neurobiological theories of depression.

METHOD

A systematic review of the scientific literature on the subject was conducted in February 2013, searching the Web of Knowledge, PubMed (Medline), PsycInfo and Cochrane electronic databases.

RESULTS

Eighteen studies were identified measuring both depression or depressive symptoms and cytokines or immune markers in adolescents. Adolescents with depression show age-specific characteristics of the immune and inflammatory system, specifically in NK cell activity and in pro-inflammatory cytokines (such as IL-1β and TNF-α). In addition, the role of cytokines in adolescent depression is influenced by neurodevelopment, hormonal changes, stress and trauma.

CONCLUSIONS

There may be differences in the neurobiology of adolescent major depressive disorder (MDD) compared with adult MDD. Increased understanding of the role of cytokines in adolescent MDD may lead to improved outcomes in the treatment of adolescent depression.

Allergic rhinitis in adolescence increases the risk of depression in later life: a nationwide population-based prospective cohort study

BACKGROUND

Many cross-sectional studies have suggested an association between allergic rhinitis (AR) and depression, but the timing relationship was not determined. Using a nationwide population-based prospective cohort study (1:4, age-/gender-matched), we hypothesized that AR in adolescence would increase the risk of depression in later life.

METHODS

In all, 1673 adolescents aged 12-15 that had AR between 1996 and 2000 were recruited for our study. Cases of major depressive disorder and any depressive disorder that occurred to the end of follow-up (December 31, 2010) were identified.

RESULT

Adolescents with AR had a higher prevalence of major depression (2.5% vs. 1.2%, p<0.001) and any depressive disorder (4.9% vs. 2.8%, p<0.001) and an earlier onset of major depression (19.31 ± 2.91 vs. 20.43 ± 2.71 years, p=0.038) and any depressive disorder (19.35 ± 2.63 vs. 20.43 ± 2.62 years, p=0.002) compared with the controls. The Cox regression model showed that adolescents with AR had increased HRs of major depression (HR: 1.59, 95% CI: 1.02-2.50) and any depressive disorder (HR: 1.42, 95% CI: 1.04-1.93) after controlling residence location and comorbid allergic diseases.

LIMITATIONS

The prevalence of depressive disorder may be underestimated because only those who had medicine-seeking behaviors were enrolled.

CONCLUSIONS

This first cohort case-control study showed an association between AR in early adolescence and depression in late adolescence and early adulthood. Our results suggested that allergic responses played important roles in the development of depression.

Targeting IL-1 in depression

INTRODUCTION

Depression is associated with inflammation, Th1 and Th17 responses, oxidative and nitrosative stress (O&NS), autoimmune responses against neoantigenic determinants, and neuroprogression (i.e., neurodegeneration, impaired plasticity and reduced neurogenesis). These pathways involve increased monocytic activation and interleukin-1 (IL-1) levels.

AREAS COVERED

This review will highlight the putative role of IL-1 in depression and the potential use of IL-1 signaling blockade as a treatment of depression. Electronic databases, i.e., Scopus, PUBMED and Google Scholar were employed using keywords: depression, depressive-like, interleukin-1, and interleukin-1 receptor antagonist (IL-1RA).

EXPERT OPINION

Ample studies show that depression is accompanied by increased levels of IL-1 and IL-1RA, which attenuates the pro-inflammatory activities of IL-1. In some, but not all studies, antidepressant treatment decreased IL-1β levels. In translational models, IL-1β administration elicits depressive-like behaviors, neuroinflammation and neuroprogression, whereas treatment with IL-1RA yields antidepressant-like effects and attenuates neuroprogression. Anakinra, an IL-1RA, targets not only IL-1 signaling, but also Th1, Th17, O&NS and neuroprogressive pathways and therefore may be advanced to clinical Phase-II trials in depression due to medical conditions associated with an elevated IL-1/IL-1RA ratio.