Cumulative meta-analysis of interleukins 6 and 1β, tumour necrosis factor α and C-reactive protein in patients with major depressive disorder

Middle frontal gyrus volume mediates the relationship between interleukin-1β and antidepressant response in major depressive disorder

Inflammation is a leading biological risk factor contributing to unfavorable outcomes of major depressive disorder (MDD). Both inflammation and depression are associated with similar alterations in brain structure, indicating that brain structural alterations could serve as a mediating factor in the adverse influence of inflammation on clinical outcomes in MDD. Nonetheless, longitudinal research has yet to confirm this hypothesis. Therefore, this study aimed at elucidating the relationships between peripheral inflammatory cytokines, gray matter volume (GMV) alterations, and antidepressant response in MDD. We studied 104 MDD patients treated with selective serotonin reuptake inhibitors and 85 healthy controls (HCs). Antidepressant response was assessed after 8-week antidepressant treatment by changes in 17-item Hamilton Depression Rating Scale (HAMD-17) scores. The GMV alterations were investigated using a voxel-based morphometry analysis. Inflammatory cytokines were measured using flow cytometry. Partial correlations were used to explore the relationships between inflammatory cytokines, GMV alterations, and antidepressant response. Compared to HCs, MDD patients showed reduced GMVs primarily in the frontal-limbic area, right insula, and right superior temporal gyrus. Furthermore, the alterations in GMVs, particularly in the right middle frontal gyrus and the left anterior cingulate gyrus, were associated with ΔHAMD-17 and inflammatory cytokines. Additionally, GMV alterations in the right middle frontal gyrus mediated the negative relationship between interleukin -1β and ΔHAMD-17. This study contributes to understanding the effect of inflammation on the brain and their relationships with antidepressant response, offering a potential explanation for the connection between inflammatory status and treatment efficacy.

The association between adverse experiences and longitudinal allostatic load changes with the depression symptoms trajectories in middle-aged and older adults in China: A longitudinal study

BACKGROUND

This study investigated the associations between adverse childhood experiences (ACEs), adverse adulthood experiences (AAEs), allostatic load (AL) changes, and later depression symptoms trajectories in middle-aged and older Chinese longitudinally.

METHODS

1921 individuals aged ≥45 years at baseline were included from the China Health and Retirement Longitudinal Study (CHARLS). Measures included ACEs, AAEs, depression symptoms scores, health-related factors, and demographic characteristics. AL changes were assessed by the difference in AL scores between wave 3 (2015) and wave 1(2011).

RESULTS

Compared to consistently low trajectory, 2 or more ACEs (OR 1.78, 95 % CI 1.28-2.46), 2 or more AAEs (OR 1.82, 95 % CI 1.26-2.64), decreasing metabolic AL over time (OR 0.63, 95 % CI 0.46-0.86), increasing inflammatory AL over time (OR 1.60, 95 % CI 1.07-2.37), and decreasing renal AL over time (OR 1.38, 95 % CI 1.01-1.87) were associated with the low-moderate depression symptoms trajectory. Furthermore, 2 or more ACEs (OR 1.48, 95 % CI 1.10-2.00), 2 or more AAEs (OR 1.85, 95 % CI 1.32-2.60), decreasing metabolic AL over time (OR 0.75, 95 % CI 0.57-1.00), increasing inflammatory AL over time (OR 1.69, 95 % CI 1.19-2.42) were associated with the high-moderate depression symptoms trajectory.

CONCLUSION

Experiencing more ACEs and AAEs was associated with higher depression symptoms trajectories. Moreover, participants with decreasing metabolic AL over time showed a low depression symptoms trajectory, while those with increasing inflammatory AL over time and decreasing renal AL over time showed a worse depression symptoms trajectory. These findings highlighted the physiological damage caused by stress on mental health outcomes.

Extra-axial inflammatory signal and its relationship to peripheral and central immunity in depression

Although both central and peripheral inflammation have been observed consistently in depression, the relationship between the two remains obscure. Extra-axial immune cells may play a role in mediating the connection between central and peripheral immunity. This study investigates the potential roles of calvarial bone marrow and parameningeal spaces in mediating interactions between central and peripheral immunity in depression. PET was used to measure regional TSPO expression in the skull and parameninges as a marker of inflammatory activity. This measure was correlated with brain TSPO expression and peripheral cytokine concentrations in a cohort enriched for heightened peripheral and central immunity comprising 51 individuals with depression and 25 healthy controls. The findings reveal a complex relationship between regional skull TSPO expression and both peripheral and central immunity. Facial and parietal skull bone TSPO expression showed significant associations with both peripheral and central immunity. TSPO expression in the confluence of sinuses was also linked to both central and peripheral immune markers. Group-dependent elevations in TSPO expression within the occipital skull bone marrow were also found to be significantly associated with central inflammation. Significant associations between immune activity within the skull, parameninges, parenchyma and periphery highlight the role of the skull bone marrow and venous sinuses as pivotal sites for peripheral and central immune interactions.

Carnosine/histidine-containing dipeptide supplementation improves depression and quality of life: systematic review and meta-analysis of randomized controlled trials

CONTEXT

Mental ill-health is a common and growing issue, affecting 1 in 8 individuals or 970 million people worldwide in 2019. Histidine-containing dipeptides (HCDs) have been suggested to mitigate some aspects of mental ill-health, but a quantitative synthesis of the evidence is lacking. Therefore, a systematic review and meta-analysis of randomized controlled trials was conducted.

OBJECTIVE

To summarize the evidence on the effects of HCDs on mental health outcomes.

DATA SOURCE

A systematic literature search was performed using electronic databases (Medline via Ovid, Embase via Ovid, Scopus, Google Scholar, and Cochrane) from inception to October, 2022.

DATA EXTRACTION

Two authors independently extracted data using a structured extraction format.

DATA ANALYSIS

Data analysis was performed using STATA version 17. Random-effects models were used, and heterogeneity was assessed using the I2 test. Quality appraisal was performed using the Cochrane risk-of-bias 2.0 tool and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach.

CONCLUSION

5507 studies were identified, with 20 studies fulfilling the inclusion criteria. Eighteen studies comprising 776 participants were included in the meta-analysis. HCD supplementation (anserine/carnosine, l-carnosine, β-alanine) caused a significant reduction in depression scores measured with the Becks Depression Inventory (-0.79; 95% CI: -1.24, -0.35; moderate certainty on GRADE) when compared with placebo. An increase in quality-of-life scores measured with the 36-item Short-Form survey (SF-36) (0.65; 95% CI: 0.00, 1.30) and low certainty on GRADE in HCDs (anserine/carnosine, l-carnosine, β-alanine) when compared with placebo were found. However, the rest of the outcomes did not show a significant change between HCD supplementation and placebo. Although the number of studies included in the meta-analysis was modest, a significant mean reduction was observed in depression score as well as an increase in quality-of-life score for the HCD group when compared with placebo. Most of the studies included had small sample sizes with short follow-up periods and moderate to high risk of bias, highlighting the need for further, well-designed studies to improve the evidence base.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42017075354.

Resting-state functional connectivity is correlated with peripheral inflammatory markers in patients with major depressive disorder and healthy controls

BACKGROUND

Recent studies have highlighted the significant role of inflammation in the development and progression of major depressive disorder (MDD). Elevated levels of proinflammatory cytokines have consistently been observed in MDD, and these markers are shown to be linked to disruptions in brain networks. Therefore, we aimed to explore the relationship between inflammatory markers and resting-state functional connectivity (RSFC) in patients with MDD.

METHODS

This study included 76 patients with MDD and 92 healthy controls (HCs). Seed-to-voxel RSFC analysis was performed using brain regions that have been identified in previous studies on the neural networks implicated in MDD. These regions served as key hubs in the default mode, salience, cognitive control, and frontostriatal networks and were used as seed regions.

RESULTS

Compared with HCs, patients with MDD exhibited elevated levels of interleukin (IL)-6 and IL-8. The MDD group showed significant alterations of the RSFC between the prefrontal cortex (PFC), anterior cingulate cortex, visual cortex, postcentral gyrus, and striatal regions compared to the HC group. Additionally, within the MDD group, a positive correlation was observed between tumor necrosis factor (TNF)-α levels and the RSFC of the right dorsolateral prefrontal cortex (dlPFC) and visual cortex. Conversely, in the HC group, TNF-α levels were negatively correlated with the RSFC between the right dlPFC and bilateral dorsomedial prefrontal cortex, while positive correlations were noted between the RSFC of the right dlPFC with occipital regions and the levels of both IL-8 and TNF-α.

CONCLUSIONS

The present study confirmed that cytokine levels are linked to alterations in the RSFC, particularly in the prefrontal regions. Our findings suggest that systemic inflammation may contribute to functional disruptions in the brain networks involved in emotion regulation and cognitive control in MDD.

A Two-Year cohort study examining the impact of cytokines and chemokines on cognitive and psychiatric outcomes in Long-COVID-19 patients

This study investigates the relationship between clinical, sociodemographic, and neuropsychological symptoms and serum cytokine concentrations with long-term cognitive and psychiatric outcomes in long-COVID-19 patients. We reassessed 108 adults who survived moderate to severe COVID-19 at two intervals post-discharge (T1, mean 6.9 months; T2, mean 23.5 months). Baseline sociodemographic and clinical data were collected from hospital records, while cognitive and mental health assessments included psychometric tests such as the Hospital Anxiety and Depression Scale (HADS) and Immediate and Delayed Recall Tests from the CERAD Battery. Serum cytokine levels were measured at T1. Generalized Additive Models (GAMs), Elastic Net Regression (NET), and Psychological Network Analysis (PNA) were used to analyze the data. The GAM analysis revealed significant associations between acute COVID-19 severity and Epworth Sleepiness Score with persistent anxiety symptoms at T2. For depression, both WHO severity class and Eotaxin levels were significant predictors. The Anti-inflammatory Index showed a marginally significant relationship with immediate recall, while age was marginally associated with delayed recall performance. In NET, only anxiety was significantly associated with Epworth Sleepiness Score, WHO severity class, and Proinflammatory Index. PNA did not reveal direct connections between cytokines and neuropsychological outcomes in the graphical model. However, centrality measures indicated that the Proinflammatory Index and VEGF were more central within the network, suggesting they might be important components of the overall system. This study provides insights into the complex role of cytokines and inflammation in long-COVID-19 outcomes, potentially aiding in the identification of biomarkers for diagnosis and prognosis.

Deep immunophenotyping of circulating immune cells in major depressive disorder patients reveals immune correlates of clinical course and treatment response

Major Depressive Disorder (MDD) is a widespread psychiatric condition impacting social and occupational functioning, making it a leading cause of disability. The diagnosis of MDD remains clinical, based on the Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 criteria, as biomarkers have not yet been validated for diagnostic purposes or as predictors of treatment response. Traditional treatment strategies often follow a one-size-fits-all approach obtaining suboptimal outcomes for many patients who fail to experience response or recovery. Several studies have reported an association between MDD and immune system dysregulation, but few have focused on the deep characterization of circulating cells, during the acute phase of MDD. This work aimed at immunophenotyping peripheral blood cells in the relapse phase of the disorder, to identify relevant cell populations for clinical monitoring of patients. Multiparametric analysis was performed on the peripheral blood of 60 MDD patients using flow cytometry to identify lymphocytes (naïve/effector, memory, regulatory) and myeloid cells (dendritic cells, monocytes). We studied the associations between immunophenotype and depressive symptoms, social and working functioning, and subjective quality of life during the acute phase and after three months of treatment. Multivariate analysis showed that CD4+ terminally differentiated effector memory (TEMRA) were associated with more depressive symptoms with a particular emphasis on anhedonic features and worse social and working functioning and quality of life. CD8+ TEMRA were associated with those depressive symptoms related to hopelessness. Conversely, ICOS + Tregs were associated with low-intensity suicidal ideation, suggestive of a protective role. Baseline T CD4+ effector memory (EM) was a negative predictor of reduction of depressive symptoms after three months of treatment, whilst plasmacytoid dendritic cells (pDC) were predicting reduction of hopelessness. These results confirm the involvement of the immune system in MDD and demonstrate the existence of immunological signatures associated with the severity of major depressive episodes and treatment response that could guide clinical monitoring and future personalized therapies.

Inflammatory proteins related to depression in multiple sclerosis: A systematic review and meta-analysis

Background

Up to 50% of individuals with multiple sclerosis (MS) experience depression. Depression has been accompanied by increases in inflammatory proteins. This meta-analysis summarized the data on inflammatory protein concentrations and level of depression in individuals with MS.

Methods

We performed a meta-analysis of studies measuring inflammatory protein concentrations and level of depression in individuals with MS with a database search of the English literature (to October 2024) and a manual search of references. Quality of evidence was also assessed.

Results

Fifteen studies involving measurements of inflammatory proteins and level of depression in 1102 individuals with MS were included in the meta-analysis: five for interleukin (IL)-10 (LPS and PHA), four for tumour necrosis factor (TNF)-α, four for interferon (IFN)-γ, and four for IL-6 (LPS and PHA). A meta-analysis showed that higher concentrations of TNF-α, IFN-γ, IL-6 and IL-10 were significantly associated with higher levels of depression in individuals with MS (r = 0.35, 95% CI [0.6,0.03], p = .015. Meta-analyses undertaken for individual inflammatory proteins of IFN-γ and IL-10 found positive associations between these proteins and level of depression although these did not reach statistical significance. Most studies were rated 'poor quality'.

Conclusion

This meta-analysis reports significant associations between higher concentrations of TNF-α, IFN-γ, IL-6 and IL-10 and level of depresson in individuals with MS. Future longitudinal studies with improved reporting of data are needed to replicate these results and confirm the mechanisms through which these inflammatory proteins are present. Meta-analytic findings lend support to depression being associated with the activation of the inflammatory system in individuals with MS.

Genome-wide Mendelian randomization mapping the influence of plasma proteome on major depressive disorder

Plasma proteins play critical roles in a series of biological processes and represent a major source of translational biomarkers and drug targets. In this study, we performed Mendelian randomization (MR) to explore potential causal associations of protein quantitative trait loci (pQTL, n = 54,219) with major depressive disorder (MDD) using summary statistics from the PGC (n = 143,265) and further replicated in FinnGen cohort (n = 406,986). Subsequently, gene expression quantitative trait loci (eQTL) of identified proteins were leveraged to validate the primary findings in both PGC and FinnGen cohorts. We implemented reverse causality detection using bidirectional MR analysis, Steiger test, Bayesian co-localization and phenotype scanning to further strengthen the MR findings. In primary analyses, MR analysis revealed 2 plasma protein significantly associated with MDD risk at Bonferroni correction (P < 3.720 × 10-5), including butyrophilin subfamily 2 member A1 (BTN2A1, OR = 0.860; 95 % CI, 0.825-0.895; P = 1.79 × 10-5) and butyrophilin subfamily 3 member A2 (BTN3A2, OR = 1.071; 95 % CI, 1.056-1.086; P = 3.89 × 10-6). Both the identified proteins had no reverse causality. Bayesian co-localization indicated that BTN2A1 (coloc.abf-PPH4 = 0.620) and BTN3A2 (coloc.abf-PPH4 = 0.872) exhibited a shared variant with MDD, a finding that was subsequently validated by HEIDI test. In the replication stage, BTN2A1 and BTN3A2 were successfully validated in the FinnGen cohort. This study genetically determined BTN2A1 and BTN3A2 were associated with MDD and these findings may have clinical implications for MDD prevention.

Associations between metabolic syndrome and depression, and the mediating role of inflammation: Based on the NHANES database

BACKGROUND

Individuals with metabolic syndrome (MetS) have an increased risk of depressive symptoms, with inflammation hypothesized to mediate this association. This study used data from the National Health and Nutrition Examination Survey (NHANES) (2015-2020) to investigate the relationship between MetS and depression and assess the mediating role of inflammatory markers.

METHODS

This cross-sectional study included 20,520 participants. MetS was defined using the NCEP ATP III criteria. Depressive symptoms were assessed with the Patient Health Questionnaire-9 (PHQ-9), with scores ≥10 indicating clinical significance. Inflammatory markers evaluated included C-reactive protein (CRP), white blood cell count (WBC), and neutrophil-to-lymphocyte ratio (NLR), among others. Multivariable linear and logistic regression models were applied to examine associations, and mediation analysis was conducted to evaluate the potential mediating effects.

RESULTS

Overall, 7.64 % of participants exhibited depressive symptoms. MetS was associated with an increased risk of depression in both females (OR: 1.49, 95 % CI: 1.28-1.74) and males (OR: 1.32, 95 % CI: 1.09-1.60) after adjusting for confounders. Among MetS components, central obesity, hypertension, and dyslipidemia demonstrated the strongest associations with depression. Inflammatory markers mediated 26.79 % of the MetS-depression relationship, with CRP contributing the largest proportion (17.24 %).

CONCLUSION

MetS and its components significantly increase the risk of depressive symptoms, with the relationship partially mediated by inflammatory markers. Chronic inflammation may play a critical role in linking MetS to depression, underscoring the importance of integrated management strategies targeting both metabolic and mental health.

Particulate matter 2.5 (PM2.5) - associated cognitive impairment and morbidity in humans and animal models: a systematic review

Particulate matter with an aerodynamic diameter of less than 2.5 µm (PM2.5) is one of the criteria air pollutants that (1) serve as an essential carrier of airborne toxicants arising from combustion-related events including emissions from industries, automobiles, and wildfires and (2) play an important role in transient to long-lasting cognitive dysfunction as well as several other neurological disorders. A systematic review was conducted to address differences in study design and various biochemical and molecular markers employed to elucidate neurological disorders in PM2.5 -exposed humans and animal models. Out of 340,068 scientific publications screened from 7 databases, 312 studies were identified that targeted the relationship between exposure to PM2.5 and cognitive dysfunction. Equivocal evidence was identified from pre-clinical (animal model) and human studies that PM2.5 exposure contributes to dementia, Parkinson disease, multiple sclerosis, stroke, depression, autism spectrum disorder, attention deficit hyperactivity disorder, and neurodevelopment. In addition, there was substantial evidence from human studies that PM2.5 also was associated with Alzheimer's disease, anxiety, neuropathy, and brain tumors. The role of exposome in characterizing neurobehavioral anomalies and opportunities available to leverage the neuroexposome initiative for conducting longitudinal studies is discussed. Our review also provided some areas that warrant consideration, one of which is unraveling the role of microbiome, and the other role of climate change in PM2.5 exposure-induced neurological disorders.

The relationship between plasma interleukin-6 and cognition based on curve correlation in drug-naïve patients with major depressive disorder

BACKGROUND

The effect of interleukin-6 (IL-6) on cognition in patients with major depressive disorder (MDD) remains unclear. The aim of the present study was to investigate for the first time the non-linear relationship between plasma IL-6 and cognition and its sex-specific associations in patients with drug-naïve MDD.

METHODS

A total of 326 participants, including 237 drug-naïve MDD patients and 89 healthy controls (HCs), were included in this study. All participants completed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and fasting venous blood was collected for IL-6 measurement. Patients with MDD completed the Hamilton Depression Scale-17 (HAMD-17) and the Hamilton Anxiety Scale-14 (HAMA-14) assessments. Two-way analysis of variance and curve estimation analyses were used to explore the effects of IL-6 on cognition and its sex differences.

RESULTS

We found that IL-6 and cognition were associated in different patterns in HCs and MDD patients. The best model for curve estimation between IL-6 and attention (F = 2.736, p = 0.045) and HAMA (F = 6.416, p < 0.001) in females with MDD was the cubic model. In male MDD patients, the best model for curve estimation between IL-6 and immediate memory was the cubic model (F = 3.077, p = 0.034). However, in HCs, the best model for curve estimation analysis between IL-6 and language was the quadratic model (F = 3.803, p = 0.026).

LIMITATIONS

The main limitations were cross-sectional design.

CONCLUSION

There was a non-linear and sex-specific relationship between IL-6 levels and cognition in patients with MDD.

Role of depression, suicide attempt history and childhood trauma in neutrophil-to-lymphocyte ratio dynamics: A 30-week prospective study

Studying the biology of suicidal behaviour and developing blood-based biomarkers may help stratify individuals with suicidal behaviors into clinically relevant categories. Literature suggests that people diagnosed with mood disorders and suicidal behaviour show an increased neutrophil to lymphocyte ratio (NLR). For the first time, we investigated NLR variability in mood disorders, a critical aspect of biomarker development. Our study provides a result on the influence of our variables on the NLR and also on the intrinsic properties of the ratio. Consequently, our objective was to analyse the differences in NLR between healthy subjects and patients diagnosed with mood disorder with suicidal behaviour or mood disorder without suicidal attempt. A prospective study was conducted on 97 healthy subjects, 63 patients with mood disorder without suicidal behaviour and 61 patients with mood disorder with suicidal behaviour (mean age [SD] = 44.2 [14.31]; 66.1 % female). Participants were assessed four times over 30 weeks, where blood samples and clinical data were collected. After controlling for confounding factors such as smoking and medical history, we found that NLR stability was low but NLR was significantly associated with a history of suicide attempt (mixed linear model, F = 4.044; p = 0.018). We also observed a significant interaction between NLR values and childhood trauma (p = 0.002). Furthermore, our results demonstrate that NLR is influenced by childhood trauma, including in controls (p = 0.014). Finally, NLR expression differs between patients with and without suicidal behaviour, but only in those without a history of childhood trauma (p = 0.026). Despite its variability over time, our data suggest that NLR may be a promising biomarker for identifying individuals at high risk of suicidal behaviour among patients with mood disorders.

Relationship between systemic immune-inflammation index and depression among individuals with and without cardiovascular disease

OBJECTIVE

Depression is a common comorbidity in cardiovascular disease (CVD), and both conditions are associated with chronic inflammation. The systemic immune-inflammation index (SII) has emerged as a promising marker of systemic inflammation, but its role in association with depressive symptoms, particularly in the context of CVD, remains unclear. This study aims to investigate the association of SII with depressive symptoms in individuals with and without CVD using cross-sectional data from NHANES (2005-2016).

METHODS

A total of 29,479 participants from the National Health and Nutrition Examination Survey (NHANES) 2005-2016 waves were included. Depressive symptoms were assessed through Patient's Health Questionnaire (PHQ-9). SII was calculated as the platelet count × neutrophil count/lymphocyte count. In order to determine the relationships between SII and depressive symptoms in participants with and without CVD, binary logistic regression model and smooth curve fitting were used. We also performed sensitivity analyses and subgroup analysis.

RESULTS

The total prevalence of depressive symptoms was 8.73% among the 29,479 participants analyzed. After adjusting for confounding factors, a higher SII was significantly associated with increased depressive symptoms in the total population (OR per SD increase: 1.101, 95% CI: 1.060-1.144, P < 0.0001). This association was stronger in participants without CVD (OR: 1.121, 95% CI: 1.073-1.172, P < 0.0001) compared to those with CVD (OR: 1.055, 95% CI: 0.973-1.144, P = 0.19571). Participants in the highest SII tertile had a significantly higher risk of depressive symptoms compared to those in the lowest tertile, particularly in the non-CVD group (OR: 1.161, 95% CI: 1.026-1.313, P = 0.01765).

CONCLUSION

The SII is independently associated with an increased risk of depressive symptoms, particularly in individuals without CVD. These findings suggest that the SII may serve as a valuable predictor of depressive symptoms in the general population, with potential implications for early screening and intervention strategies. Further research is needed to elucidate the mechanisms underlying this association and to explore the clinical utility of SII in depressive symptoms assessment, especially in the context of cardiovascular health.

Dissecting depression symptoms: Multi-omics clustering uncovers immune-related subgroups and cell-type specific dysregulation

In a subset of patients with mental disorders, such as depression, low-grade inflammation and altered immune marker concentrations are observed. However, these immune alterations are often assessed by only one data type and small marker panels. Here, we used a transdiagnostic approach and combined data from two cohorts to define subgroups of depression symptoms across the diagnostic spectrum through a large-scale multi-omics clustering approach in 237 individuals. The method incorporated age, body mass index (BMI), 43 plasma immune markers and RNA-seq data from peripheral mononuclear blood cells (PBMCs). Our initial clustering revealed four clusters, including two immune-related depression symptom clusters characterized by elevated BMI, higher depression severity and elevated levels of immune markers such as interleukin-1 receptor antagonist (IL-1RA), C-reactive protein (CRP) and C-C motif chemokine 2 (CCL2 or MCP-1). In contrast, the RNA-seq data mostly differentiated a cluster with low depression severity, enriched in brain related gene sets. This cluster was also distinguished by electrocardiography data, while structural imaging data revealed differences in ventricle volumes across the clusters. Incorporating predicted cell type proportions into the clustering resulted in three clusters, with one showing elevated immune marker concentrations. The cell type proportion and genes related to cell types were most pronounced in an intermediate depression symptoms cluster, suggesting that RNA-seq and immune markers measure different aspects of immune dysregulation. Lastly, we found a dysregulation of the SERPINF1/VEGF-A pathway that was specific to dendritic cells by integrating immune marker and RNA-seq data. This shows the advantages of combining different data modalities and highlights possible markers for further stratification research of depression symptoms.

A Cross-Sectional Trait Versus State Biomarker Analysis of Inflammatory Cytokines and miRNAs in Patients with Major Depressive Disorder

Background

Inflammatory cytokines are associated with the pathophysiology of major depressive disorder (MDD). Nevertheless, whether they are trait or state biomarkers remains unclear. We aimed to assess and compare selected cytokines, miRNAs, and oxidative stress biomarker levels between patients with MDD, first-degree relatives (FDRs), and unrelated healthy controls (UHCs).

Methods

Using a cross-sectional design, we recruited patients with MDD, their FDRs and age, gender, body mass index-matched UHCs. Serum levels of IL-6, IL-1β, TNF-α, hs-CRP, and IL-10 were evaluated using the Enzyme-Linked Immunosorbent Assay (ELISA) method. We quantified the gene expressions of plasma miR-16, miR-132, and miR-1202 using Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). We estimated the total oxidant status and total antioxidant status levels in the serum by ELISA. We used sequential multiple linear regression analysis to find the association between MDD vs. UHCs (model 1), FDRs vs. UHCs (model 2), and MDD vs. FDRs (model 3) after adjusting for age, gender, and BMI as covariates.

Results

The study involved 50 patients with MDD (mean age = 34.7 ± 10.1 years), 31 FDRs (mean age = 32.7 ± 12.2 years), and 50 UHCs (mean age = 34.1 ± 10.3 years). Patients with MDD had higher levels IL-6 (β = 6.04; 95% CI; 1.60 to 10.49; p = 0.008) and downregulated miR-1202 (β = -0.38; 95% CI: -0.70 to -0.06; p = 0.02) compared to FDRs with statistically significant differences.

Conclusion

The higher levels of serum IL-6 and downregulated plasma miR-1202 expression in patients with MDD compared to FDRs may be a state biomarkers in MDD. However, an adequately powered study can answer these questions with certainty.

Enhancing predictive accuracy for antidepressant response in depressive disorders: The additive value of interleukin-1β and interleukin-6 alongside hsCRP

BACKGROUND

This study aimed to evaluate the potential additive effects of measuring serum interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) on enhancing the predictive value of baseline serum high-sensitivity C-reactive protein (hsCRP) levels for predicting 12-week antidepressant treatment responses in patients with depressive disorders.

METHODS

Serum levels of hsCRP, IL-1β, and IL-6 were measured at baseline in 1086 outpatient participants diagnosed with depressive disorders. Participants initially received monotherapy with antidepressants for the first three weeks, followed by a naturalistic, stepwise pharmacotherapy regimen administered every three weeks up to 12 weeks. Remission was defined as achieving a score of ≤7 on the Hamilton Depression Rating Scale. Logistic regression models were employed to analyze the data, adjusting for demographic and clinical covariates.

RESULTS

Higher baseline levels of hsCRP, IL-1β, and IL-6 were significantly associated with lower rates of remission at 12 weeks. Notably, the inclusion of IL-1β and IL-6 levels alongside hsCRP significantly enhanced the model's predictive accuracy, revealing robust interaction effects among these biomarkers.

LIMITATION

Serum biomarkers were solely measured at baseline and various antidepressants in stepwise psychopharmacotherapy should be considered.

CONCLUSION

The addition of IL-1β and IL-6 measurements to hsCRP testing could significantly refine the prediction of antidepressant treatment outcomes. These findings support the integration of multiple inflammatory markers into clinical practice, advancing personalized medicine approaches in the treatment of depressive disorders. Further replication studies and randomized controlled trials are encouraged to validate and extend these preliminary findings.

Bifidobacterium longum CECT 30763 improves depressive- and anxiety-like behavior in a social defeat mouse model through the immune and dopaminergic systems

Adolescence is a crucial period marked by profound changes in the brain. Exposure to psychological stressors such as bullying, abuse or maltreatment during this developmental period may increase the risk of developing depression, anxiety and comorbid cardiometabolic conditions. Chronic psychological stress is associated with behavioral changes and disruption of the hypothalamic-pituitary-adrenal axis, leading to corticosterone overproduction in rodents and changes in both the immune system and the gut microbiome. Here, we demonstrate the ability of Bifidobacterium longum CECT 30763 (B. longum) to ameliorate adolescent depressive and anxiety-like behaviors in a chronic social defeat (CSD) mouse model. The mechanisms underlying this beneficial effect are related to the ability of B. longum to attenuate the inflammation and immune cell changes induced by CSD after the initial stress exposure through the induction of T regulatory cells with enduring effects that may prevent and mitigate the adverse consequences of repeated stress exposure on mental and cardiometabolic health. B. longum administration also normalized dopamine release, metabolism and signaling at the end of the intervention, which may secondarily contribute to the reversal of behavioral changes. The anti-inflammatory effects of B. longum could also explain its cardioprotective effects, which were reflected in an amelioration of the oxidative stress-induced damage in the heart and improved lipid metabolism in the liver. Overall, our findings suggest that B. longum regulates the links between the immune and dopaminergic systems from the gut to the brain, potentially underpinning its beneficial psychobiotic and physiological effects in CSD.

Network analysis of depressive symptoms and C-reactive protein levels in major depressive disorder

BACKGROUND

C-reactive protein (CRP) levels have been implicated in the severity and symptomatology of major depressive disorder (MDD). The aim of this study was to explore the structure of depressive symptoms in patients with MDD according to different groups of CRP levels using network analysis.

METHODS

The study included 864 individuals (mean age = 54.05, 67.48 % male) diagnosed with MDD from the 2015-2020 National Health and Nutrition Examination Survey (NHANES). Analyses examined how depressive symptoms and CRP level were related to each other, and how the network structure of depressive symptoms differed across groups with different CRP levels.

RESULTS

A direct positive correlation was observed between CRP levels and specific depressive symptoms (e.g., appetite change, energy loss, and feelings of worthlessness). Moreover, there was a stronger correlation between depressive symptoms in the medium CRP and high CRP groups compared to the low CRP group. Furthermore, it was observed that there were notable structural differences between the high-CRP and moderate-CRP groups.

LIMITATIONS

The study is based on cross-sectional data, which precludes the drawing of causal conclusions. Furthermore, it does not take into account confounding factors such as body mass index (BMI) and lifestyle.

CONCLUSIONS

The findings underscore the pivotal role of CRP as a marker of the severity of depressive symptoms. Routine CRP level testing and anti-inflammatory therapies may be beneficial for depressed patients with elevated CRP levels in clinical practice.

Unraveling the Role of the Blood-Brain Barrier in the Pathophysiology of Depression: Recent Advances and Future Perspectives

Depression is a highly prevalent psychological disorder characterized by persistent dysphoria, psychomotor retardation, insomnia, anhedonia, suicidal ideation, and a remarkable decrease in overall well-being. Despite the prevalence of accessible antidepressant therapies, many individuals do not achieve substantial improvement. Understanding the multifactorial pathophysiology and the heterogeneous nature of the disorder could lead the way toward better outcomes. Recent findings have elucidated the substantial impact of compromised blood-brain barrier (BBB) integrity on the manifestation of depression. BBB functions as an indispensable defense mechanism, tightly overseeing the transport of molecules from the periphery to preserve the integrity of the brain parenchyma. The dysfunction of the BBB has been implicated in a multitude of neurological disorders, and its disruption and consequent brain alterations could potentially serve as important factors in the pathogenesis and progression of depression. In this review, we extensively examine the pathophysiological relevance of the BBB and delve into the specific modifications of its components that underlie the complexities of depression. A particular focus has been placed on examining the effects of peripheral inflammation on the BBB in depression and elucidating the intricate interactions between the gut, BBB, and brain. Furthermore, this review encompasses significant updates on the assessment of BBB integrity and permeability, providing a comprehensive overview of the topic. Finally, we outline the therapeutic relevance and strategies based on BBB in depression, including COVID-19-associated BBB disruption and neuropsychiatric implications. Understanding the comprehensive pathogenic cascade of depression is crucial for shaping the trajectory of future research endeavors.

Tadalafil pretreatment attenuates doxorubicin-induced hepatorenal toxicity by modulating oxidative stress and inflammation in Wistar rats

Doxorubicin (DOX) is a widely used anticancer agent, but its clinical application is limited by significant off-target hepatorenal toxicity. Tadalafil (TAD), a selective phosphodiesterase-5 inhibitor used mainly for erectile dysfunction and pulmonary arterial hypertension, has shown potential in reducing oxidative stress. This study investigated TAD's chemoprotective effects and underlying mechanisms in DOX-induced hepatorenal toxicity in rats over 12 days. Eight groups of six rats each were orally pretreated with sterile water, silymarin (SIL), or TAD one hour before receiving intraperitoneal injections of 2.5 mg/kg DOX. On the 13th day, the rats were humanely sacrificed under inhaled halothane anesthesia, and serum was collected for hepatic and renal function tests, while liver and kidney tissues were analyzed for antioxidant enzyme activity, pro-inflammatory cytokines assay, and histopathological evaluation. DOX successfully induced hepatorenal toxicity, evidenced by significant increases (p<0.001, p<0.0001) in serum K+, urea, and creatinine levels, along with decreases in HCO3 -, TCa2+, and Cl-. Tissue analysis showed reduced SOD, CAT, GST, and GPx activities, with elevated MDA and GSH levels. TAD pretreatment significantly ameliorated these biochemical alterations (p<0.05, p<0.001, p<0.0001), suggesting its potential as an effective chemoprophylactic adjuvant in the development of DOX-induced hepatorenal toxicity.

Inflammation and depression: A study protocol to dissect pathogenetic mechanisms in the onset, comorbidity and treatment response

About one third of patients suffering from Major Depressive Disorder (MDD) do not respond to any antidepressant medications and 75% experience relapses and general health deterioration. Importantly, inflammation can contribute to such negative outcomes, as well as to cause depression in patients who have been exposed to adverse childhood experiences and/or to viral infections, including COVID-19. Depressed patients also have an increased risk for developing comorbidities, such as cardio-metabolic dysfunctions, where inflammatory alterations, again, play a role in connecting MDD and these comorbid conditions. Here, we present our study protocol funded by the Italian Ministry of Health in the context of the PNRR call (M6/C2_CALL 2022; Project code: PNRR-MAD-2022-12375859). The project aims to clarify the role of inflammation: i) in the onset of depression in association with environmental factors; ii) in the mechanisms associated with treatment response/resistance; iii) in depression and its comorbidity. To reach all these aims, we will perform biochemical, transcriptomic, genetic variants analyses on inflammatory/immune genes, pharmacokinetics and machine learning techniques, taking advantage of different human cohorts (adolescent depressed patients exposed to childhood trauma; adult depressed patients; treatment resistant depression patients; both prevalent and incident depression cases identified within a large population cohort). Moreover, we will use in vitro models (primary cultures of astrocytes, neurons and microglia) treated with pro-inflammatory or stressful challenges and preventive compounds to clarify the underlying mechanisms. This 2-years project will increase the knowledge on the role of inflammation in the prevention and treatment of MDD and in comorbid disorders, and it will also provide experimental evidence for the development of novel targets and tools for innovative personalized intervention strategies.

Associations between mental illness, TB risk and migrant status

BACKGROUND

TB and mental illnesses are public health priorities that often co-exist, with migrants in high-income countries being at risk for both conditions. This study investigates whether mental illness influences TB risk and examines the impact of migration status.

METHODS

A nationwide prospective cohort study was conducted in Denmark from 1994-2015, involving migrants matched 1:6 to Danish-born individuals. Cox regression models, adjusted for age, sex and migrant status, were used to assess the effect of mental disorders on TB risk.

RESULTS

Both migrants and non-migrants with mental disorders showed elevated TB incidence (n = 1,189,273). After adjusting for age and sex, the hazard ratio (HR) for TB in those with any mental disorder was 3.62 (95% CI 2.99-4.39, P < 0.001) compared to those without mental disorders. The effect was more substantial in Danish-born individuals (HR 15.51, 95% CI 12.05-19.95, P < 0.001) than in migrants (HR 1.37, 95% CI 0.99-1.90, P = 0.055). Sub-analyses highlighted a significant effect of substance use (HR 5.49, 95% CI 4.46-6.76, P < 0.001) and psychosis (HR 4.19, 95% CI 1.74-10.08, P = 0.001) and borderline significance for affective/anxiety/stress-related disorders (HR 1.64, 95% CI 0.98-2.73, P = 0.058) on TB risk.

CONCLUSIONS

People with mental illnesses, particularly psychotic and substance use disorders, have increased TB incidence and represent a high-risk population for targeted screening and treatment. TB programmes should integrate holistic mental health care.

Association of the neutrophil-to-platelet ratio with response to electroconvulsive therapy in adolescents with major depressive disorder

Background

Major depressive disorder (MDD) is one of the most serious mental disorders affecting adolescents worldwide. Electroconvulsive therapy (ECT) is widely acknowledged as a first-line treatment for severe depression, but the clinical response varies. Neutrophils and platelets are both related to the progression of MDD. The aim of this study was to investigate the correlation between the neutrophil-to-platelet ratio (NPR) during the acute phase and the effectiveness of ECT treatment.

Methods

A total of 138 adolescent MDD patients who received ECT were included in the study. Neutrophil and platelet levels were obtained upon admission. At the same time, treatment response was the primary outcome measure, defined as a reduction of ≥ 50% in the HAMD-17 score from baseline to treatment endpoint, and the secondary outcome measure was remission of depression, defined as a HAMD-17 score ≤ 7.

Results

After receiving ECT, 103(74.6%) of all patients responded to treatment and 72(52.2%) achieved remission. Non-responders/non-remitters to ECT tended to have higher levels of NPR at baseline compared to ECT responders/remitters [Non-responder: 3.4 (2.5-4.8) vs 2.7 (2.2-3.5), P = 0.002; Non-remitter: 0.014 (0.011-0.017) vs 0.011 (0.008-0.015), P = 0.03]. In multiple logistic regression, high NPR (≥ 0.014) remained independently associated with ECT non-response/non-remission after adjusting for confounding factors [Non-responder: OR = 4.911, 95% CI (2.052 - 11.754), P < 0.001; Non-remitter: OR = 2.704, 95% CI (1.262 - 5.796), P = 0.011].

Conclusion

High NPR correlates with poor ECT efficacy in adolescents with MDD, particularly among female and overweight patients.

A Method for Detecting Depression in Adolescence Based on an Affective Brain-Computer Interface and Resting-State Electroencephalogram Signals

Depression is increasingly prevalent among adolescents and can profoundly impact their lives. However, the early detection of depression is often hindered by the time-consuming diagnostic process and the absence of objective biomarkers. In this study, we propose a novel approach for depression detection based on an affective brain-computer interface (aBCI) and the resting-state electroencephalogram (EEG). By fusing EEG features associated with both emotional and resting states, our method captures comprehensive depression-related information. The final depression detection model, derived through decision fusion with multiple independent models, further enhances detection efficacy. Our experiments involved 40 adolescents with depression and 40 matched controls. The proposed model achieved an accuracy of 86.54% on cross-validation and 88.20% on the independent test set, demonstrating the efficiency of multimodal fusion. In addition, further analysis revealed distinct brain activity patterns between the two groups across different modalities. These findings hold promise for new directions in depression detection and intervention.

Serum biomarkers, lifetime substance use and conversion to bipolar disorder

INTRODUCTION

The diagnostic conversion of major depressive disorder (MDD) to bipolar disorder (BD) is a topic that is currently the subject of several studies. However, there are few studies that clarify the interaction between conversion, substance use and biomarkers.

OBJECTIVES

The aim of this study was to investigate serum biomarker levels and lifetime substance use as predictors for diagnostic conversion from major depressive disorder to bipolar disorder in an outpatient sample of adults.

METHODS

This was a prospective longitudinal study nested within a larger two-phase study. Male and female individuals, between the ages of 18 and 60, diagnosed with MDD by the Mini International Neuropsychiatric Interview Plus who participated in the two stages of the study were included. The instrument alcohol smoking and substance involvement screening test (ASSIST) was used to evaluate substance use. The enzyme linked immuno sorbent assay (ELISA) technique was used to measure the levels of the following biomarkers: brain derived neurotrophic factor (BDNF), nerve growth factor (NGF), glial cell line-derived neurotrophic factor (GDNF), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α).

RESULTS

The conversion rate from MDD to BD was 12.4%. The prevalence of female individuals, subjects with up to eight years of schooling, who had lifetime psychotic symptoms and reported lifetime use of cocaine was higher among individuals who converted their diagnosis to BD than among individuals who did not (P<0.05). In the crude analysis, there was no interaction between biomarkers and substance use except for NGF with cocaine. Based on the adjusted analysis model, it was observed that the interaction remains (OR: 1.476; 95% CI: 1.019-2.137).

CONCLUSIONS

Individuals with late diagnosis and treatment of bipolar disorder may have a worse prognosis. Therefore, results suggesting that NGF and cocaine use are potential predictors of conversion to bipolar disorder can help in clinical practice, contributing to the identification of conversion and to more specific therapeutic interventions.

Higher inflammatory proteins predict future depressive symptom severity among adolescents with lower emotional clarity

BACKGROUND

A growing body of work has implicated inflammation in the pathogenesis of depression. As not all individuals with heightened levels of peripheral inflammation develop symptoms of depression, additional work is needed to identify other factors that catalyze the relationship between inflammation and depressive symptoms. Given that elevated levels of inflammatory activity can induce a variety of emotional changes, the present study examined whether emotional clarity, the trait-like ability to identify, discern, and express one's emotions, influences the strength of the association between inflammatory signaling and concurrent and prospective symptoms of depression.

METHODS

Community adolescents (N = 225, Mage = 16.63 years), drawn from a larger longitudinal project investigating sex and racial differences in depression onset, provided blood samples to determine peripheral levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) at a baseline visit, along with self-report measures of emotional clarity and depressive symptom severity. Depressive symptom severity was assessed again at a follow-up visit approximately 5-months after baseline.

RESULTS

Hierarchical multiple regressions detected a significant interaction between inflammatory markers and emotional clarity on future depression severity, controlling for baseline depressive symptoms. Specifically, among adolescents with low levels of emotional clarity, higher levels of IL-6, CRP, and inflammatory composite scores were significantly associated with greater future depression severity.

CONCLUSIONS

These results indicate that low emotional clarity and high inflammatory signaling may jointly confer risk for prospective depressive symptom severity among adolescents. Therapeutic interventions that improve emotional clarity may reduce risk of depressive symptoms among adolescents with low-grade peripheral inflammation.

Associations between prenatal stress with offspring inflammation, depression and anxiety

PURPOSE

Few longitudinal studies have investigated the mediating role of inflammation during childhood in associations between prenatal maternal stress and adolescent mental health. The objective of this study was to examine the associations between prenatal maternal stress, concentrations of immune markers at age 9, and symptoms of generalized anxiety disorder (GAD) and depression during adolescence.

METHODS

This study included 3723 mother-child pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC). Prenatal maternal stress was examined using 55 items measured during pregnancy. Inflammation was assessed using serum concentrations of interleukin-6 (IL-6) and C-reactive protein (CRP) when children were 9 years old. GAD and depression were assessed when children were 16 and 18 years of age, respectively. Analyses comprised of structural equation models.

RESULTS

Prenatal maternal stress was associated with higher concentrations of IL-6 in childhood, and with greater symptoms of depression and GAD in adolescence. However, we did not observe associations between prenatal maternal stress and CRP; also, CRP and IL-6 were not associated with depression and GAD. There was no evidence that CRP and IL-6 mediated the associations between prenatal maternal stress and either GAD or depression.

CONCLUSIONS

Prenatal maternal stress is associated with IL-6 levels in childhood, and with GAD and depression during adolescence. Future studies should examine immune activity at multiple points during development in relation to mental health into adulthood to determine whether inflammation at different points during development could increase risk for mental health problems among children whose mothers experienced significant stressors during pregnancy.

A bio-behavioral model of systemic inflammation at breast cancer diagnosis and fatigue of clinical importance 2 years later

BACKGROUND

We aimed to generate a model of cancer-related fatigue (CRF) of clinical importance 2 years after diagnosis of breast cancer building on clinical and behavioral factors and integrating pre-treatment markers of systemic inflammation.

PATIENTS AND METHODS

Women with stage I-III hormone receptor-positive/human epidermal growth factor receptor 2-negative breast cancer were included from the multimodal, prospective CANTO cohort (NCT01993498). The primary outcome was global CRF of clinical importance [European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ)-C30 ≥40/100] 2 years after diagnosis (year 2). Secondary outcomes included physical, emotional, and cognitive CRF (EORTC QLQ-FA12). All pre-treatment candidate variables were assessed at diagnosis, including inflammatory markers [interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, interferon γ, IL-1 receptor antagonist, tumor necrosis factor-α, and C-reactive protein], and were tested in multivariable logistic regression models implementing multiple imputation and validation by 100-fold bootstrap resampling.

RESULTS

Among 1208 patients, 415 (34.4%) reported global CRF of clinical importance at year 2. High pre-treatment levels of IL-6 (quartile 4 versus 1) were associated with global CRF at year 2 [adjusted odds ratio (aOR): 2.06 (95% confidence interval [CI] 1.40-3.03); P = 0.0002; area under the receiver operating characteristic curve = 0.74]. Patients with high pre-treatment IL-6 had unhealthier behaviors, including being frequently either overweight or obese [62.4%; mean body mass index 28.0 (standard deviation 6.3 kg/m2)] and physically inactive (53.5% did not meet World Health Organization recommendations). Clinical and behavioral associations with CRF at year 2 included pre-treatment CRF [aOR versus no pre-treatment CRF: 3.99 (95% CI 2.81-5.66)], younger age [aOR per 1-year decrement: 1.02 (95% CI 1.01-1.03)], current tobacco smoking [aOR versus never: 1.81 (95% CI 1.26-2.58)], and worse insomnia or pain [aOR per 10-unit increment: 1.08 (95% CI 1.04-1.13), and 1.12 (95% CI 1.04-1.21), respectively]. Secondary analyses indicated additional associations of IL-2 [aOR per log-unit increment: 1.32 (95% CI 1.03-1.70)] and IL-10 [0.73 (95% CI 0.57-0.93)] with global CRF and of C-reactive protein [1.42 (95% CI 1.13-1.78)] with cognitive CRF at year 2. Emotional distress was consistently associated with physical, emotional, and cognitive CRF.

CONCLUSIONS

This study proposes a bio-behavioral framework linking pre-treatment systemic inflammation with CRF of clinical importance 2 years later among a large prospective sample of survivors of breast cancer.

P2X7 receptors from the perspective of NLRP3 inflammasome pathway in depression: Potential role of cannabidiol

Many patients with depressive disorder do not respond to conventional antidepressant treatment. There is an ongoing interest in investigating potential mechanisms of treatment resistance in depression to provide alternative treatment options involving inflammatory mechanisms. Increasing evidence implicates the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome as a critical factor in neuroinflammation. ATP-induced P2X7 receptor (P2X7R) activation is a major trigger for inflammation, activating the canonical NLRP3 inflammatory cascade. Psychosocial stress, the primary environmental risk factor for depression, is associated with changes in ATP-mediated P2X7R signaling. Depression and stress response can be alleviated by Cannabidiol (CBD). CBD has an anti-inflammatory activity related to the regulation of NLRP3 inflammasome activation. However, CBD's effects on the inflammasome pathway are poorly understood in central nervous system (CNS) cells, including microglia, astrocytes, and neurons. This review will emphasize some findings for neuroinflammation and NLRP3 inflammasome pathway involvement in depression, particularly addressing the ATP-induced P2X7R activation. Moreover, we will underline evidence for the effect of CBD on depression and address its potential impacts on neuroinflammation through the NLRP3 inflammasome cascade.

Predictive Value of Inflammatory Biomarkers in Assessing Major Depression in Adults

Background: There are studies that have investigated the association of pro-inflammatory cytokines with depressive disorders, but they often present certain limitations. In this study, two substantial groups of patients were analyzed: 92 patients with major depressive disorder and 76 without depressive disorders. The strict inclusion and exclusion criteria for the analyzed groups significantly increased the value of the obtained results. The research question of this study was whether levels of inflammation, measured by the inflammatory markers IL-6, IL-1α, and TNF-α, could predict the severity of depressive symptoms. This could provide additional evidence supporting the hypothesis that inflammation plays a notable role in the pathogenesis of depression. The data analysis supports the hypothesis that the biological mechanisms of inflammation contribute to the clinical manifestations of depression. Elevated levels of inflammatory markers, especially interleukins (IL-6, IL-1α) and tumor necrosis factor-alpha (TNF α), have been identified in patients with major depressive disorder compared to the findings in healthy controls. Materials and Methods: Inflammatory markers (IL-6, IL-1α, and TNF-α) were measured in a sample of 92 patients hospitalized at the Socola Institute of Psychiatry in Iasi, Romania, and compared to a control group with no depression or inflammatory conditions (n = 76). Severity of depressive symptoms was assessed using HAM-D scores. Results: The study results indicated that values of plasma inflammatory markers were significantly higher in patients with major depressive disorder (MDD) compared to the control group (IL-1α: 1.16 ± 0.44 pg/mL vs. 0.89 ± 0.25 pg/mL, p = 0.0004; IL-6: 9.21 ± 4.82 pg/mL vs. 7.16 ± 4.32 pg/mL, p = 0.0149; and TNF-α: 2.02 ± 0.96 pg/mL vs. 1.67 ± 0.8 pg/mL, p = 0.0286). The differences remained significant after applying logarithmic transformation, which was necessary to adjust for outlier values. An analysis of demographic characteristics showed that the frequency of women (67.4% vs. 36.84%, p < 0.001), cohabiting individuals (28.26% vs. 10.53%, p = 0.0001), and alcohol consumers (67.39% vs. 47.37%, p = 0.0087) was significantly higher in patients with MDD. The level of education was significantly lower in patients with MDD (median (IQR): 12 (2.5) years vs. 14 (8) years, p = 0.0016). The evaluation of confounding variables, including patients' gender, marital status, education level, and alcohol consumption, was performed using multiple linear regression models. The results indicated that these demographic variables did not significantly influence the correlation between the HAM-D score and the values of IL-6, IL-1α, and TNF-α. A significant correlation between the HAM-D score and the logarithmic values of inflammatory markers was observed for log IL-1α in men (r = 0.355, p = 0.0014), log IL-6 in women (r = 0.0313, p = 0.0027), and log TNF-α in women (r = 0.3922, p = 0.0001). The results of the multiple linear regression and predictive analysis indicated that IL-1α (AUC = 0.677, p = 0.0004), IL-6 (AUC = 0.724, p < 0.001), and TNF-α (AUC = 0.861, p < 0.001) demonstrate high accuracy in discriminating patients with MDD. Conclusions: The results highlighted that IL-6 (AUC = 0.724; 95% CI: 0.648-0.801) and TNF-α (AUC = 0.861; 95% CI: 0.797-0.925) are significant predictors for major depressive disorder. The study highlights the potential of cytokines (IL-1α, IL-6 and TNF-α) as diagnostic markers. These findings support the hypothesis that inflammation may play an important role in the development or exacerbation of depressive symptoms.

Medicinal plants and plant-based traditional medicine: Alternative treatments for depression and their potential mechanisms of action

Background

Clinical depression is a serious public health issue that affects 4.7 % of the world's population and can lead to suicide tendencies. Although drug medications are available, only 60 % of the depressed patients respond positively to the treatments, while the rest experience side effects that resulted in the discontinuation of their medication. Thus, there is an urgent need for developing a new anti-depressant with a distinct mode of action and manageable side effects. One of the options is using medicinal plants or plant-based traditional medicine as alternative therapies for psychiatric disorders.

Objectives

Therefore, the objective of this review was twofold; to identify and critically evaluate anti-depressant properties of medicinal plants or those incorporated in traditional medicine; and to discuss their possible mechanism of action as well as challenges and way forward for this alternative treatment approach.

Methods

Relevant research articles were retrieved from various databases, including Scopus, PubMed, and Web of Science, for the period from 2018 to 2020, and the search was updated in September 2024. The inclusion criterion was relevance to antidepressants, while the exclusion criteria included duplicates, lack of full-text availability, and non-English publications.

Results

Through an extensive literature review, more than 40 medicinal plant species with antidepressant effects were identified, some of which are part of traditional medicine. The list of the said plant species included Albizia zygia (DC.) J.F.Macbr., Calculus bovis Sativus, Celastrus paniculatus Willd., Cinnamomum sp., Erythrina velutina Willd., Ficus platyphylla Delile, Garcinia mangostana Linn., Hyptis martiusii Benth, and Polygonum multiflorum Thunb. Anti-depressant mechanisms associated with those plants were further characterised based on their modes of action such as anti-oxidation system, anti-inflammation action, modulation of various neurotransmitters, neuroprotective effect, the regulation of hypothalamic-pituitary-adrenal (HPA) axis and anti-depressant mechanism. The challenges and future outlook of this alternative and complementary medicine are also explored and discussed.

Conclusion

This pool of identified plant species is hoped to offer health care professionals the best possible alternatives of anti-depressants from natural phytocompounds that are efficacious, safe and affordable for applications in future clinical settings.

Evaluation of a probiotic blend on psychosocial health and biomarkers of inflammatory, immune and stress response in adults with subthreshold depression: a double-blind, randomised, placebo-controlled trial

This study examined the efficacy of a probiotic in reducing depressive symptom severity in people with subthreshold depression. In a double-blind, randomised, placebo-controlled trial, a probiotic (1 × 10^9 live cells per strain: Limosilactobacillus fermentum LF16 (DSM26956), Lacticaseibacillus rhamnosus LR06 (DSM21981), Lactiplantibacillus plantarum LP01 (LMG P-21021) and Bifidobacterium longum 04 (DSM23233)) or placebo was taken daily for 12 weeks. Data were collected at baseline, 6 and 12 weeks including psychological symptom severity (Beck Depression Inventory, BDI; Patient Health Questionnaire, PHQ; Hospital Anxiety Depression Scale, HADS; and Depression Anxiety and Stress Scale, DASS). Biomarkers of glycaemia, inflammation (high-sensitivity C-reactive protein, hs-CRP), antioxidant status (total glutathione (GSH)) and stress (cortisol awakening response, CAR) were also measured. Thirty-nine participants (nineteen probiotic; twenty placebo) were enrolled. There were no significant between-group differences in the examined psychological symptom severity scores, despite certain significant within-group changes observed in both groups from baseline to 6 and/or 12 weeks of follow-up. Regarding biomarkers, the probiotic group showed reduced hs-CRP (-1520; 95 % CI -273·7, -2766·2 ng/dl) and CAR (-0·28; 95 % CI -0·05, -0·51 μg/dl) at 12 weeks, but increased total GSH (3·9; 95 % CI 0·1, 7·5 ng/dl) at 6 weeks, compared with the placebo. The current study reported favourable decreases in depressive symptoms in both groups. Although the within-group changes observed in the probiotic group were supported by favourable inflammatory, antioxidant status and stress biomarker changes compared with the placebo, further research is required to shed more light on the role of gut microbiota modulation on emotional regulation.

The combined effects of depression or anxiety with high-sensitivity C-reactive protein in predicting the prognosis of coronary heart disease patients

BACKGROUND

Depression, anxiety and high-sensitivity C-reactive protein (hs-CRP) are individually associated with poor prognosis in patients with coronary heart disease (CHD). However, the combined effects of depression with inflammation or anxiety with inflammation on the prognosis have been rarely explored.

METHODS

This prospective cohort study included 414 patients diagnosed with CHD. The Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) were used to assess depression and anxiety. A score ≥ 5 points was defined as elevated depression or anxiety. High hs-CRP was defined as ≥ 3 mg/L. Follow-up was performed 2 years after the patients were discharged. The clinical results included noncardiac readmission, cardiac readmission, major cardiovascular events (MACEs), and composite events. The composite events included noncardiac readmission and MACEs. The Cox proportional hazard regression model was used to analyze the prognostic risk.

RESULTS

After full adjustment, patients with elevated depression and high hs-CRP had a higher risk in predicting noncardiac readmission (hazard ratio (HR) = 3.87, 95% confidence interval (CI) = 1.10-9.02, p = 0.002) and composite events (HR = 1.93, 95% CI = 1.13-3.30, p = 0.016) than those with high hs-CRP alone. For the anxiety and hs-CRP group, high hs-CRP alone predicted a higher risk of noncardiac readmission (HR = 3.32, 95% CI = 1.57-7.03, p = 0.002) and composite events (HR = 1.75, 95% CI = 1.12-2.76, p = 0.015) than references. Elevated anxiety had no significant effects on all the endpoints. Furthermore, we didn't find interactions between depression and hs-CRP or anxiety and hs-CRP.

CONCLUSION

In patients with CHD, elevated depression with high hs-CRP was found to be significant in predicting the risk of noncardiac readmission and composite events. Early diagnosis and treatment of depression with inflammation are necessary in CHD patients.

Association between TNF-α & IL-6 level changes and remission from depression with duloxetine treatment

PURPOSE/AIM OF THE STUDY

The pathophysiology of major depressive disorder (MDD) involves multiple factors, including inflammatory processes. This study investigated the relationship between changes in the levels of cytokines and remission in patients with MDD following duloxetine treatment.

MATERIALS AND METHODS

MDD patients were administered duloxetine for 16 weeks. Clinical evaluation and immunological monitoring were performed every 4 weeks.

RESULTS

Our results indicated that changes in serum levels of TNF-α and IL-6 were associated with remission following duloxetine treatment in MDD patients. There was a slight increase in TNF-α levels in the first four weeks following duloxetine treatment, which correlated significantly with patients who were in remission. Furthermore, patients in remission exhibited an initial increase in IL-6 levels in the first four weeks, followed by a decrease at 16 weeks.

CONCLUSIONS

These results suggest an important relationship between changes in cytokine levels and remission in patients with major depression after duloxetine treatment.

The role of exercise-related FNDC5/irisin in depression

The complexity of depression presents a significant challenge to traditional treatment methods, such as medication and psychotherapy. Recent studies have shown that exercise can effectively reduce depressive symptoms, offering a new alternative for treating depression. However, some depressed patients are unable to engage in regular physical activity due to age, physical limitations, and other factors. Therefore, pharmacological agents that mimic the effects of exercise become a potential treatment option. A newly discovered myokine, irisin, which is produced during exercise via cleavage of its precursor protein fibronectin type III domain-containing protein 5 (FNDC5), plays a key role in regulating energy metabolism, promoting adipose tissue browning, and improving insulin resistance. Importantly, FNDC5 can promote neural stem cell differentiation, enhance neuroplasticity, and improve mood and cognitive function. This review systematically reviews the mechanisms of action of exercise in the treatment of depression, outlines the physiology of exercise-related irisin, explores possible mechanisms of irisin's antidepressant effects. The aim of this review is to encourage future research and clinical applications of irisin in the prevention and treatment of depression.

Electroacupuncture attenuates depressive-like behaviors in poststroke depression mice through promoting hippocampal neurogenesis and inhibiting TLR4/NF-κB/NLRP3 signaling pathway

The aim of this study was to investigate the impact and underlying molecular mechanisms of electroacupuncture on mice with poststroke depression (PSD). Mice were randomly allocated into sham, PSD, and electroacupuncture groups. Mice in the PSD and electroacupuncture groups underwent middle cerebral artery occlusion (MCAO) surgery following with sedentary behavior. Electroacupuncture targeting Zusanli (ST36) acupoint was performed 24 h after MCAO for 4 weeks in electroacupuncture group. The sucrose preference test, forced swimming test, open field test, tail suspension test, elevated plus maze, Catwalk analysis, RNA sequencing, Nissl staining, Golgi staining, TUNEL staining, Edu labeling, and doublecortin staining were performed. Lymphocyte subsets in peripheral blood and the levels of IL-1β, IL-6, TNF-α, and expression of Iba1/CD86, Iba1/NLRP3, TLR4/p38/NF-κB/NLRP3 pathways in the hippocampus were detected. Electroacupuncture effectively protected against the development of depression-like symptoms. The number of granulosa cells and doublecortin-positive cells in the dentate gyrus (DG) were significantly decreased in PSD group, which were significantly upregulated ( P  < 0.01) by electroacupuncture. Electroacupuncture also significantly reduced ( P  < 0.05) TUNEL-positive cells in the DG and CA1. RNA-seq revealed that electroacupuncture may exert antidepressant effect by regulating the inflammation mediated by TLR4/NF-κB/NLRP3 pathway in hippocampus. Electroacupuncture remarkably elevated ( P  < 0.01) the ratio of CD4+ to CD8+ T cells and percentage of CD3-CD49b+ cells in CD45+CD49b+ cells in the peripheral blood. Electroacupuncture significantly reduced ( P  < 0.05) the high levels of IL-1β, IL-6, TNF-α, iba1, TLR4, p-p38, p-NF-κB, and NLRP3 and sedentary behavior. Electroacupuncture was observed to mitigate depression symptoms and increase hippocampal neurogenesis in mice with PSD, possibly by inhibiting TLR4/p38/NF-κB/NLRP3 pathways and improving the microglia-mediated inflammatory microenvironment in the hippocampus.

GSP1-111 Modulates the Microglial M1/M2 Phenotype by Inhibition of Toll-like Receptor 2: A Potential Therapeutic Strategy for Depression

Neuroinflammation plays a vital role in neurodegenerative diseases and neuropsychiatric disorders, and microglia and astrocytes chiefly modulate inflammatory responses in the central nervous system (CNS). Toll-like receptors (TLRs), which are expressed in neurons, astrocytes, and microglia in the CNS, are critical for innate immune responses; microglial TLRs can regulate the activity of these cells, inducing protective or harmful effects on the surrounding cells, including neurons. Therefore, regulating TLRs in microglia may be a potential therapeutic strategy for neurological disorders. We examined the protective effects of GSP1-111, a novel synthetic peptide for inhibiting TLR signaling, on neuroinflammation and depression-like behavior. GSP1-111 decreased TLR2 expression and remarkably reduced the mRNA expression of inflammatory M1-phenotype markers, including tumor necrosis factor (TNF)α, interleukin (IL)-1β, and IL-6, while elevating that of the M2 phenotype markers, Arg-1 and IL-10. In vivo, GSP1-111 administration significantly decreased the depression-like behavior induced by lipopolysaccharide (LPS) in a forced swim test and significantly reduced the brain levels of M1-specific inflammatory cytokines (TNFα, IL-1β, and IL-6). GSP1-111 prevented the LPS-induced microglial activation and TLR2 expression in the brain. Accordingly, GSP1-111 prevented inflammatory responses and induced microglial switching of the inflammatory M1 phenotype to the protective M2 phenotype. Thus, GSP1-111 could prevent depression-like behavior by inhibiting TLR2. Taken together, our results suggest that the TLR2 pathway is a promising therapeutic target for depression, and GSP1-111 could be a novel therapeutic candidate for various neurological disorders.

Association between parity and female mortality: the mediative role of depressive symptoms

STUDY QUESTION

Is parity associated with all-cause and cause-specific mortality among women in a nationally representative cohort of the US population, and does depression mediate this association?

SUMMARY ANSWER

Nulliparous women have a higher risk of all-cause and cause-specific mortality, with depression partially mediating the relationship between parity and women's all-cause and cause-specific mortality.

WHAT IS KNOWN ALREADY

Parity, a significant state in reproductive life, has enduring implications for women's health. There is also a complex relationship between depression, a prevalent mental and emotional disorder, and female fertility. Previous studies have elucidated the relationships between parity and depression, both of which are associated with mortality. However, findings from studies examining parity and women's mortality have been inconsistent. Moreover, few studies have investigated whether the effect of parity on mortality is mediated by depression.

STUDY DESIGN, SIZE, DURATION

We conducted a cross-sectional study using data from seven cycles of the National Health and Nutrition Examination Survey (NHANES) spanning 2005-2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study cohort comprised adult women with available parity and survival follow-up data. Parity data were self-reported and sourced from the Reproductive Health Questionnaire. Depression scores were derived from the Patient Health Questionnaire 9, and cause-specific deaths were identified using the International Statistical Classification of Diseases, 10th Revision (ICD-10). Weighted multivariable Cox regression was applied to analyze the association between parity, depression, and mortality. Weighted linear regression was performed to examine the relationship between parity and depression. Mediation analyses were employed to determine whether and to what extent depression mediated the effect of parity on mortality.

MAIN RESULTS AND THE ROLE OF CHANCE

Our study ultimately encompassed 16 962 American women. Following multivariable adjustment, compared to nulliparous women, those with one to three live births exhibited a 17% and 33% reduction in all-cause and cancer mortality, respectively (all-cause mortality: HR = 0.83, 95% CI = 0.69-0.99, P = 0.040; cancer mortality: HR = 0.67, 95% CI = 0.45-0.99, P = 0.045). Women with more than four live births demonstrated lower all-cause mortality and mortality from other (not cancer or cardiovascular disease) diseases (all-cause mortality: HR = 0.73, 95% CI = 0.58-0.93, P = 0.011; other diseases mortality: HR = 0.66, 95% CI = 0.47-0.91, P = 0.013). No correlation was detected between parity and the risk of cardiovascular disease mortality among women. Furthermore, depression was found to partially mediate the impact of parity on all-cause mortality and mortality from other diseases in women.

LIMITATIONS, REASONS FOR CAUTION

Firstly, a single index of parity was used as an exposure factor, and other reproductive factors such as birth spacing, age at first birth, and mode of delivery were not taken into account. Secondly, despite accounting for important potentially confounders in our analysis, such as BMI, smoking status, and educational level, the influence of unmeasured confounders (e.g., social class, latent reproductive system diseases) on reproductive behavior or mortality cannot be dismissed. Thirdly, women's vulnerability to depression fluctuates across reproductive stages, and the effect of depression on female fertility varies over time. Due to data constraints, we were unable to obtain information on women's mental health status at different reproductive stages. Fourthly, due to the data accessibility limitations of NHANES, we were unable to specifically explore the relationship between parity and different specific types of cancer, a limitation that may obscure potential correlations. Additionally, despite our efforts to control for various confounding factors in subgroup analyses, the smaller sample sizes in some subgroups may limit the statistical power, affecting the ability to detect effects. Finally, studies exploring the association between parity and depression are cross-sectional designs, making it difficult to infer causality. These results should be interpreted with caution, and further research is warranted to corroborate our findings.

WIDER IMPLICATIONS OF THE FINDINGS

Our study underscores the elevated risk of all-cause and cause-specific mortality in nulliparous women and reveals that depression partially mediates the negative correlation between parity and women's all-cause mortality and mortality from other diseases. These results should be interpreted with caution, and further investigation is needed to support our findings.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Key Research and Development Program of China (2023YFC2705700), the Key Research & Developmental Program of Hubei Province (2022BCA042), and the Interdisciplinary Innovative Talents Foundation from Renmin Hospital of Wuhan University (JCRCWL-2022-001). The authors declare that they have no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Sex differences in the inflammation-depression link: A systematic review and meta-analysis

Major Depressive Disorder (MDD) is a heterogeneous disorder that affects twice as many women than men. Precluding advances in more tailored and efficacious treatments for depression is the lack of reliable biomarkers. While depression is linked to elevations in inflammatory immune system functioning, this relationship is not evident among all individuals with depression and may vary based on symptom subtypes and/or sex. This systematic review and meta-analysis examined whether inflammatory immune peripheral markers of depression are sex-specific. PRISMA guidelines were followed for the systematic review, and a comprehensive search strategy that identified studies from PubMed and PsycInfo was applied. Studies were included if they reported C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α and/or IL-1β for males and/or females among depressed and healthy adults. We identified 23 studies that satisfied these inclusion criteria. Random-effects meta-analysis models were fit, and measures of association were summarized between levels of circulating markers of inflammation in depressed and healthy males and females. Sex-based analyses revealed elevated levels of CRP among females with depression (Cohen's d = 0.19) relative to their healthy counterparts (p = 0.02), an effect not apparent among males (Cohen's d = -0.01). Similarly, levels of IL-6 were increased among females with depression compared to healthy controls (Cohen's d = 0.51; p = 0.04), but once again this was not found among males (Cohen's d = 0.16). While TNF-α levels were elevated among individuals with depression compared to controls (p = 0.01), no statistically significant sex differences were found. The meta-analysis for IL-1β resulted in only three articles, and thus, results are presented in the supplemental section. This meta-analysis advances our understanding of the unique involvement of inflammatory biomarkers in depression among men and women, which may help inform more tailored sex-specific treatment approaches in the future.

T helper-1 activation via interleukin-16 is a key phenomenon in the acute phase of severe, first-episode major depressive disorder and suicidal behaviors

BACKGROUND

Immune-inflammatory pathways in major depressive disorder are confined to the major dysmood disorder (MDMD) phenotype (Maes et al., 2022). No studies have addressed the immune profile of first episode MDMD (FE-MDMD).

METHODS

This study investigated the immune profiles of 71 patients with the acute phase of first-episode major depressive disorder (FE-MDMD) and 40 healthy controls. We measured 48 cytokines/chemokines/growth factors, classical M1, alternative M2, T helper (Th)-1, Th-2, and Th-17 phenotypes, immune-inflammatory response system (IRS), compensatory immunoregulatory system (CIRS), and neuro-immunotoxicity profiles.

RESULTS

FE-MDMD patients show significantly activated M1, M2, Th-1, IRS, CIRS, and neurotoxicity, but not Th-2 or Th-17, profiles compared to controls. FE-MDMD is accompanied by Th-1 polarization, while there are no changes in M1/M2 or IRS/CIRS ratios. The top single indicator of FE-MDMD was by far interleukin (IL)-16, followed at a distance by TRAIL, IL-2R, tumor necrosis factor (TNF)-β. The severity of depression and anxiety was strongly associated with IRS (positively) and Th-2 (inversely) profiles, whereas suicidal behavior was associated with M1 activation. Around 56-60% of the variance in depression, anxiety, and suicidal behavior scores was explained by IL-16, platelet-derived growth factor (PDGF) (both positively), and IL-1 receptor antagonist (inversely). Increased neurotoxicity is mainly driven by IL-16, TNF-α, TRAIL, IL-6, and chemokine (CCL2, CCL11, CXCL1, CXCL10) signaling. Antidepressant-treated patients show an increased IRS/CIRS ratio as compared with drug-naïve FE-MDMD patients.

CONCLUSIONS

FE-MDMD is accompanied by positive regulation of the IRS mainly driven by Th-1 polarization and T cell activation (via binding of IL-16 to CD4), and TNF, chemokine, and growth factor signaling.

Cardiovascular disease and psychiatric disorders: An-up-to date review

Cardiovascular diseases (CVD) and mental health disorders (MHD) are respectively the first and second most prevalent diseases in high-income countries and the two most relevant causes of disability worldwide. The close association between the two conditions has been known for a long time and research has been able to document how the co-morbidity between cardiovascular disorders and mental health disorders is a negative prognostic factor for both conditions. This strong connection and the relevance of the impact of the association have led to define a new branch of cardiology, known as behavioral cardiology. The aim of the new branch is just to study the nexus CVD-MHD in order to prevent or decrease the burden of MHD on CVD and vice versa. This review describes the epidemiological evidence of the relationship between MHD on CVD at the state of the art among clinical research.

The Role of Inflammation in Depression and Beyond: A Primer for Clinicians

PURPOSE OF REVIEW

We evaluate available evidence for the role of inflammation in depression. We reappraise literature involving systemic inflammation, neuroinflammation and neurotransmission and their association with depression. We review the connection between depression, autoimmunity and infectious diseases. We revise anti-inflammatory treatments used in depression.

RECENT FINDINGS

Peripheral inflammatory markers are present in a subset of patients with depression and can alter common neurotransmitters in this population but there is no clear causality between depression and systemic inflammation. Infectious conditions and autoimmune illnesses do not have a clear correlation with depression. Certain medications have positive evidence as adjunctive treatments in depression but studies are heterogenic, hence they are sparsely used in clinical settings. The current evidence does not fully support inflammation, infections or autoimmunity as possible etiologies of depression. The available studies have numerous confounders that obscure the findings. Anti-inflammatory agents may have potential for treatment of depression, but further research is needed to clarify their usefulness in routine clinical practice.

Inulae Flos has Anti-Depressive Effects by Suppressing Neuroinflammation and Recovering Dysfunction of HPA-axis

Depression is a debilitating mood disorder that causes persistent feelings of sadness, emptiness, and a loss of joy. However, the clinical efficacy of representative drugs for depression, such as selective serotonin reuptake inhibitors, remains controversial. Therefore, there is an urgent need for more effective therapies to treat depression. Neuroinflammation and the hypothalamic-pituitary-adrenal (HPA) axis are pivotal factors in depression. Inulae Flos (IF), the flower of Inula japonica Thunb, is known for its antioxidant and anti-inflammatory effects. This study explored whether IF alleviates depression in both in vitro and in vivo models. For in vitro studies, we treated BV2 and PC12 cells damaged by lipopolysaccharides or corticosterone (CORT) with IF to investigate the mechanisms of depression. For in vivo studies, C57BL/6 mice were exposed to chronic restraint stress and were administered IF at doses of 0, 100, and 300 mg/kg for 2 weeks. IF inhibited pro-inflammatory mediators, such as nitric oxide, inducible nitric oxide synthase, and interleukins in BV2 cells. Moreover, IF increased the viability of CORT-damaged PC12 cells by modulating protein kinase B, a mammalian target of the rapamycin pathway. Behavioral assessments demonstrated that IF reduced depression-like behaviors in mice. We found that IF reduced the activation of microglia and astrocytes, and regulated synapse plasticity in the mice brains. Furthermore, IF lowered elevated CORT levels in the plasma and restored glucocorticoid receptor expression in the hypothalamus. Collectively, these findings suggest that IF can alleviate depression by mitigating neuroinflammation and recovering dysfunction of the HPA-axis.

Balancing the mind: Toward a complete picture of the interplay between gut microbiota, inflammation and major depressive disorder

The intricate interplay existing between gut microbiota and homeostasis extends to the realm of the brain, where emerging research underscores the significant impact of the microbiota on mood regulation and overall neurological well-being and vice-versa, with inflammation playing a pivotal role in mediating these complex interactions. This comprehensive review explores the complex interplay between inflammation, alterations in gut microbiota, and their impact on major depressive disorder (MDD). It provides a cohesive framework for the puzzle pieces of this triad, emphasizing recent advancements in understanding the gut microbiota and inflammatory states' contribution to the depressive features. Two directions of communication between the gut and the brain in depression are discussed, with inflammation serving as a potential modulator. Therapeutic implications were discussed as well, drawing insights from interventional studies on the effects of probiotics on gut bacterial composition and depressive symptoms. Ultimately, this review will attempt to provide a complete and valuable framework for future research and therapeutic interventions in MDD.

Inflammatory biomarkers in depression: scoping review

BACKGROUND

Inflammation is increasingly recognised as a fundamental component of the pathophysiology of major depressive disorder (MDD), with a variety of inflammatory biomarkers playing pivotal roles. These markers are closely linked to both the severity of symptoms and the responsiveness to treatments in MDD.

AIMS

This scoping review aims to explore the scientific literature investigating the complex relationships between inflammatory biomarkers and depression, by identifying new studies and critical issues in current research.

METHOD

Following the PRISMA Extension for Scoping Reviews guidelines, we systematically searched databases including PubMed, Scopus, PsycINFO, Open Grey and Cochrane Library. Our search focused on articles published from 1 January 2020 to 1 May 2024. We included studies evaluating inflammatory biomarkers in adult patients with MDD, utilising observational and randomised controlled trial designs, and review studies.

RESULTS

Our analysis examined 44 studies on the complex interplay between inflammation and its multiple effects on MDD. Significant associations between specific inflammatory biomarkers and depression severity were found, requiring cautious interpretation. We also highlight several methodological limitations in the current studies, which warrant caution in directly applying these findings to clinical practice. However, identified methodologies show potential for using these biomarkers as diagnostic tools or therapeutic targets, including anti-inflammatory interventions.

CONCLUSIONS

The findings emphasise the need for sophisticated, integrative research to understand inflammation's role in MDD. Future studies should identify specific biomarker panels for diagnosing depression and bridging peripheral biomarker measurements with central neuroinflammatory processes, leading to better diagnostic and treatment strategies.

Depression and inflammation in COVID-19 patients during and after hospitalisation – a systematic review and meta-analysis

Introduction: The severity of depression symptoms in COVID-19 patients differs among populations investigated and changes over time. Increasing evidence supports the hypothesis about the involvement of inflammation in the development of depression. Methods: A systematic review and a meta-analysis of the cross-sectional and cohort studies published between 2019 and 2023 were conducted according to the PRISMA criteria. The outcomes of interest were the proportions of mild, moderate, and severe depression symptoms during and after hospitalisation, and associations between depression and inflammation in COVID-19 patients. Results: Thirty articles were included in the systematic review. In the quantitative meta-analysis, the overall proportions of moderate-to-severe and mild-to-severe depression were estimated at 0.21 (95% CI: 0.13–0.31) and 0.35 (95% CI: 0.23–0.48), respectively. The fixed effects model of the meta-analysis of inflammatory markers showed a difference between COVID-19 patients with and without depression, with higher concentrations of both C-reactive protein and neutrophil-lymphocyte ratio detected among people suffering mood disturbances. However, in random effects models, findings for C-reactive protein lost significance, and for neutrophil-lymphocyte ratio were on the boundary of significance (p = 0.053). Conclusions: According to the study results, the proportion of depression decreases over time after a COVID-19 diagnosis. The relationship between depression and inflammation is still uncertain and requires further research.

Possible roles of neuropeptide/transmitter and autoantibody modulation in emotional problems and aggression

The theoretical foundations of understanding psychiatric disorders are undergoing changes. Explaining behaviour and neuroendocrine cell communication leaning towards immunology represents a different approach compared to previous models for understanding complex central nervous system processes. One such approach is the study of immunoglobulins or autoantibodies, and their effect on peptide hormones in the neuro-endocrine system. In the present review, we provide an overview of the literature on neuropeptide/transmitter and autoantibody modulation in psychiatric disorders featuring emotional problems and aggression, including associated illness behaviour. Finally, we discuss the role of psycho-immunology as a growing field in the understanding of psychiatric disorders, and that modulation and regulation by IgG autoAbs represent a relatively new subcategory in psycho-immunology, where studies are currently being conducted.

Intron retention as an excellent marker for diagnosing depression and for discovering new potential pathways for drug intervention

Background

Peripheral inflammation is often associated with depressive disorders, and immunological biomarkers of depression remain a focus of investigation.

Methods

We performed RNA-seq analysis of RNA transcripts of human peripheral blood mononuclear cells from a case-control study including subjects with self-reported depression in the pre-symptomatic state of major depressive disorder and analyzed differentially expressed genes (DEGs) and the frequency of intron retention (IR) using rMATS.

Results

Among the statistically significant DEGs identified, the 651 upregulated DEGs were particularly enriched in the term "bacterial infection and phagocytosis", whereas the 820 downregulated DEGs were enriched in the terms "antigen presentation" and "T-cell proliferation and maturation". We also analyzed 158 genes for which the IR was increased (IncIR) and 211 genes for which the IR was decreased (DecIR) in the depressed subjects. Although the Gene Ontology terms associated with IncIR and DecIR were very similar to those of the up- and downregulated genes, respectively, IR genes appeared to be particularly enriched in genes with sensor functions, with a preponderance of the term "ciliary assembly and function". The observation that IR genes specifically interact with innate immunity genes suggests that immune-related genes, as well as cilia-related genes, may be excellent markers of depression. Re-analysis of previously published RNA-seq data from patients with MDD showed that common IR genes, particularly our predicted immune- and cilia-related genes, are commonly detected in populations with different levels of depression, providing validity for using IR to detect depression.

Conclusion

Depression was found to be associated with activation of the innate immune response and relative inactivation of T-cell signaling. The DEGs we identified reflect physiological demands that are controlled at the transcriptional level, whereas the IR results reflect a more direct mechanism for monitoring protein homeostasis. Accordingly, an alteration in IR, namely IncIR or DecIR, is a stress response, and intron-retained transcripts are sensors of the physiological state of the cytoplasm. The results demonstrate the potential of relative IR as a biomarker for the immunological stratification of depressed patients and the utility of IR for the discovery of novel pathways involved in recovery from depression.

Dual Approach to Depression: The Combined Efficacy of Intermittent Hypoxia and Fluoxetine in Modulating Behavioral and Inflammatory Responses

Background/Objectives: Mental disorders pose a significant public health challenge, affecting millions worldwide. Given the limitations of current therapies, many patients experience inadequate responses and adverse effects. Intermittent hypoxia (IH) has demonstrated anxiolytic, antidepressant, and neuroprotective properties in various protocols. This study investigated the effects of acute IH (13% O2, 1 h), fluoxetine (FLX) and their combination on depression-like behavior, serum corticosterone, and inflammatory cytokine levels induced by acute restraint stress in C57BL/6 female mice. Methods: Behavioral assessments included the tail suspension test, forced swim test, and open field test. Results: The combined IH + FLX treatment exhibited a synergistic effect, reducing immobility time and increasing latency time, respectively, in the tail suspension test (46%, p = 0.0014; 73%, p = 0.0033) and forced swim test (56%, p = 0.0082; 48%, p = 0.0322) compared to the ARS group. Biochemical analysis revealed that individual and combined treatments significantly reduced most inflammatory interleukins by up to 96%. Corticosterone levels were reduced by 30% only in the IH group. Conclusions: These findings highlight the potential of a one-hour IH session, particularly when combined with fluoxetine, to alleviate depressive-like behaviors and exert anti-inflammatory effects, suggesting a promising therapeutic approach for depression.