Peripheral blood inflammatory markers in depression: Response to electroconvulsive therapy and relationship with cognitive performance

Electroconvulsive Therapy Changes Immunological Markers in Patients With Major Depressive Disorder: A Scoping Review

ABSTRACT

Major depressive disorder (MDD) is a highly prevalent and disabling condition. As such, understanding the causes of and treatment options for MDD is critical. Electroconvulsive therapy (ECT) remains the gold standard depression treatment, but the molecular mechanisms that underlie its effects are still largely unknown. One such explanation hinges on the immuno-inflammatory correlates of ECT treatment, given mounting evidence supporting the inflammatory hypothesis of depression. This review aims to provide an overview of the suggested immunomodulatory effects of ECT and the predictive value of immune biomarkers in relation to treatment outcomes and side effects. We conducted a preregistered, systematic literature search utilizing MEDLINE (PubMed), Embase (Elsevier), and PsycINFO (EBSCO) databases. We employed keywords related to MDD, ECT, gut microbiome, and the immune system. We only included human subjects research published between 1985 and January 13, 2021. Twenty-six unique studies were included in our analyses. Findings indicate a proinflammatory profile associated with MDD, with immune biomarkers exhibiting acute and chronic changes following ECT. Consistently, lower baseline interleukin 6 levels and higher C-reactive protein levels are correlated with a greater reduction in depressive symptoms following ECT. Furthermore, included studies emphasize the predictive value of peripheral immune changes, specifically interleukin 6 and tumor necrosis factor α, on cognitive outcomes following ECT. Given these results, further exploration of the potential roles of immunomodulatory effects on ECT treatment outcomes, as well as adverse cognitive side effects, is indicated.

Changes in IL-6, IL-12, IL-5, IL-10 and TGF-β1 Concentration in Patients with Treatment-Resistant Schizophrenia (TRS) Following Electroconvulsive Therapy (ECT)-A Pilot Study

Background/Objectives: Treatment-resistant schizophrenia (TRS) may be considered as a neuro-immune disorder. Electroconvulsive therapy (ECT) remains an important therapeutic option for patients with TRS, however, its impact on cytokine profile is barely investigated. Therefore, this study attempts to establish associations between serum cytokines IL-6, IL-12, IL-5, IL-10 and TGF-β1 changes (pre- and post-ECT) and the effectiveness of ECT in TRS patients. The second aim is to search for correlations between serum concentrations of the above specified cytokines and psychometric assessments of clinical schizophrenia symptoms. Methods: The cytokine concentrations were measured in eight TRS patients on psychopharmacological treatment prior to and following ECT and in 13 control subjects. Psychopathology assessment was based on the Positive and Negative Syndrome Scale (PANSS). Results: Prior to ECT, IL-10 concentration was significantly higher in TRS patients, while IL-5 was decreased in comparison to the controls. A significant concentration decrease in the pro-inflammatory cytokines IL-6 (p = 0.012), IL-12 (p = 0.049) and anti-inflammatory IL-10 (p = 0.012) post-ECT vs. pre-ECT was observed, whereas concentrations of IL-5 and TGF-β1 did not significantly change. Also, a significant decrease in schizophrenia symptoms measured by the PANSS post-ECT was found. Furthermore, the pattern of correlations between PANSS scores and cytokine concentrations was different when comparing levels pre- and post-ECT. Additionally, correlations between changes in PANSS scores and cytokine concentrations were found. Conclusions: These results may indicate the probable impact of electroconvulsive therapy on the balance between pro- and anti-inflammatory cytokines, which may correspond to a neurobiological therapeutic effect of ECT in TRS patients.

Relationship between the triglyceride-glucose index and depression in individuals with chronic kidney disease: A cross-sectional study from National Health and Nutrition Examination Survey 2005-2020

Accumulating evidence indicates that individuals with chronic kidney disease (CKD) are at an increased risk of experiencing depressive disorders, which may accelerate its progression. However, the relationship between the triglyceride-glucose (TyG) index and depression in CKD individuals remains unclear. Therefore, this cross-sectional study aimed to assess whether such a relationship exists. To this end, the CKD cohort of the National Health and Nutrition Examination Survey from 2005 to 2020 was analyzed using multivariable logistic regression analyses and a generalized additive approach. A recursive algorithm was employed to pinpoint the turning point, constructing a dual-segment linear regression model. The study included 10,563 participants. After controlling for all variables, the odds ratios and 95% confidence intervals indicated a 1.24 (range, 1.09-1.42) relationship between the TyG index and depression in the CKD cohort. The findings underscored an asymmetrical association, with a pivotal value at a TyG index 9.29. Above this threshold, the adjusted odds ratio (95% confidence interval) was 1.10 (range, 0.93-1.31). This relationship was significant among the obese subgroups. The study results highlight the complex relationship between the TyG index and depression among American adults with CKD.

The Regulation of Frontal Cortex Cholesterol Metabolism Abnormalities by NR3C1/NRIP1/NR1H2 Is Involved in the Occurrence of Stress-Induced Depression

Stress-induced alterations in central neuron metabolism and function are crucial contributors to depression onset. However, the metabolic dysfunctions of the neurons associated with depression and specific molecular mechanisms remain unclear. This study initially analyzed the relationship between cholesterol and depression using the NHANES database. We then induced depressive-like behaviors in mice via restraint stress. Applying bioinformatics, pathology, and molecular biology, we observed the pathological characteristics of brain cholesterol homeostasis and investigated the regulatory mechanisms of brain cholesterol metabolism disorders. Through the NHANES database, we initially confirmed a significant correlation between cholesterol metabolism abnormalities and depression. Furthermore, based on successful stress mouse model establishment, we discovered the number of cholesterol-related DEGs significantly increased in the brain due to stress, and exhibited regional heterogeneity. Further investigation of the frontal cortex, a brain region closely related to depression, revealed stress caused significant disruption to key genes related to cholesterol metabolism, including HMGCR, CYP46A1, ACAT1, APOE, ABCA1, and LDLR, leading to an increase in total cholesterol content and a significant decrease in synaptic proteins PSD-95 and SYN. This indicates cholesterol metabolism affects neuronal synaptic plasticity and is associated with stress-induced depressive-like behavior in mice. Adeno-associated virus interference with NR3C1 in the prefrontal cortex of mice subjected to short-term stress resulted in reduced protein levels of NRIP1, NR1H2, ABCA1, and total cholesterol content. At the same time, it increased synaptic proteins PSD95 and SYN, effectively alleviating depressive-like behavior. Therefore, these results suggest that short-term stress may induce cholesterol metabolism disorders by activating the NR3C1/NRIP1/NR1H2 signaling pathway. This impairs neuronal synaptic plasticity and consequently participates in depressive-like behavior in mice. These findings suggest that abnormal cholesterol metabolism in the brain induced by stress is a significant contributor to depression onset.

Association between triglyceride glucose index and depression in hypertensive population

Growing evidence suggests that hypertensive individuals have a greater risk of developing depression, and depression can also increase the incidence of hypertension. In the hypertensive population, the association between triglyceride glucose (TyG) index and depression remains unclear. This study aimed to assess the association between TyG index and depression in hypertensive people through the cross-sectional study of the National Health and Nutrition Examination Survey (2007-2018). To assess the relationship between TyG index and depression in hypertensive population, we conducted weighted multiple logistic regression models and used a generalized additive model to probe for nonlinear correlations. In addition, we employed a recursive algorithm to determine the inflection point and established a two-piece linear regression model. This study enrolled 5897 individuals. In the model adjusted for all covariates, the ORs (95% CI) for the relationship between TyG index and depression in hypertensive population were 1.32 (1.12-1.54). A nonlinear association was found between TyG index and depression, with an inflection point at 8.7. After the inflection point, the ORs (95% CI) were 1.44 (1.15-1.79). Only the interaction with the obese population was statistically significant. Our study highlighted a nonlinear association between TyG index and depression in American hypertensive adults.

Human in vivo evidence of reduced astrocyte activation and neuroinflammation in patients with treatment-resistant depression following electroconvulsive therapy

AIM

The current study aimed to investigate the neuroinflammatory hypothesis of depression and the potential anti-inflammatory effect of electroconvulsive therapy (ECT) in vivo, utilizing astrocyte-derived extracellular vesicles (ADEVs) isolated from plasma.

METHODS

A total of 40 patients with treatment-resistant depression (TRD) and 35 matched healthy controls were recruited at baseline, and 34 patients with TRD completed the post-ECT visits. Blood samples were collected at baseline and post-ECT. Plasma ADEVs were isolated and confirmed, and the concentrations of two astrocyte markers (glial fibrillary acidic protein [GFAP] and S100β), an extracellular vesicle marker cluster of differentiation 81 (CD81), and nine inflammatory markers in ADEVs were measured as main analyses. In addition, correlation analysis was conducted between clinical features and ADEV protein levels as exploratory analysis.

RESULTS

At baseline, the TRD group exhibited significantly higher levels of two astrocyte markers GFAP and S100β, as well as CD81 compared with the healthy controls. Inflammatory markers interferon γ (IFN-γ), interleukin (IL) 1β, IL-4, IL-6, tumor necrosis factor α, IL-10, and IL-17A were also significantly higher in the TRD group. After ECT, there was a significant reduction in the levels of GFAP, S100β, and CD81, along with a significant decrease in the levels of IFN-γ and IL-4. Furthermore, higher levels of GFAP, S100β, CD81, and inflammatory cytokines were associated with more severe depressive symptoms and poorer cognitive function.

CONCLUSION

This study provides direct insight supporting the astrocyte activation and neuroinflammatory hypothesis of depression using ADEVs. ECT may exert an anti-inflammatory effect through inhibition of such activation of astrocytes.

Whole blood mitochondrial DNA copy number in depression and response to electroconvulsive therapy

Mitochondrial dysfunction may play a role in various psychiatric conditions. Mitochondrial DNA copy number (mtDNAcn), the ratio of mitochondrial DNA to nuclear DNA, represents an attractive marker of mitochondrial health that is easily measured from stored DNA samples, and has been shown to be altered in depression. In this study, we measured mtDNAcn in whole blood samples from medicated patients with depression (n = 100) compared to healthy controls (n = 89) and determined the relationship between mtDNAcn and depression severity and the therapeutic response to electroconvulsive therapy (ECT). We also explored the relationship between mtDNAcn and telomere length and inflammatory markers. Our results show that mtDNAcn was significantly elevated in blood from patients with depression when compared to control samples, and this result survived statistical adjustment for potential confounders (p = 0.002). mtDNAcn was significantly elevated in blood from subgroups of patients with non-psychotic or unipolar depression. There was no difference in mtDNAcn noted in subgroups of ECT remitters/non-remitters or responders/non-responders. Moreover, mtDNAcn was not associated with depression severity, telomere length, or circulating inflammatory marker concentrations. Overall, our results show that mtDNAcn is elevated in blood from patients with depression, though whether this translates to mitochondrial function is unknown. Further work is required to clarify the contribution of mitochondria and mtDNA to the pathophysiology of depression and the therapeutic response to antidepressant treatments.

Association between inflammatory cytokines and symptoms of major depressive disorder in adults

Objective

This study investigated the association between inflammatory cytokines and major depressive disorder.

Methods

Plasma biomarkers were measured by enzyme-linked immunosorbent assay (ELISA). Statistical analysis of baseline biomarkers in the major depression disorder (MDD) group and healthy controls (HC) group, and differences in biomarkers before and after treatment. Spearman analysis was performed to correlate baseline and after treatment MDD biomarkers with the 17-item Hamilton Depression Rating Scale (HAMD-17) total scores. Receiver operator characteristic (ROC) curves were analyzed for the effect of biomarkers on MDD and HC classification and diagnosis.

Results

Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels were significantly higher in the MDD group than in the HC group, while high mobility group protein 1 (HMGB1) levels were significantly lower in the MDD group. The AUCs for HMGB1, TNF-α, and IL-6 were 0.375, 0.733, and 0.783, respectively, according to the ROC curves. MDD patients with brain-derived neurotrophic factor precursor (proBDNF) levels were positively correlated with total HAMD-17 scores. The levels of proBDNF levels were positively correlated with the total HAMD-17 score in male MDD patients, and brain-derived neurotrophic factor (BDNF) and interleukin 18 (IL-18) levels were negatively correlated with the total HAMD-17 score in female MDD patients.

Conclusion

Inflammatory cytokines are associated with the severity of MDD, and TNF-α and IL-6 have the potential as objective biomarkers to aid in the diagnosis of MDD.

Blood cell ratios in mood and cognitive outcomes following electroconvulsive therapy

Systemic inflammation is commonly reported in depression, with dysregulation of both the innate and adaptive arms of the immune system documented. Obtaining ratios of neutrophils, platelets, and monocytes to counts of lymphocytes (NLR, PLR, MLR, respectively) represents a low-cost and easily reproducible measure of an individual's inflammatory burden that can be calculated effortlessly from routine clinical full white blood cell counts. Electroconvulsive therapy (ECT) remains the most effective acute antidepressant treatment for depression but is often limited by its cognitive side-effects. Here, we examined differences in blood cell ratios in subgroups of depressed patients (unipolar/bipolar, psychotic/non-psychotic, early-onset/late-onset) and ECT-related subgroups (responder/non-responder, remitter/non-remitter). We also explored the relationships between blood cell ratios and depression severity and immediate cognitive outcomes post-ECT. Our results show baseline NLR was raised in patients with psychotic depression. In the entire group of patients, significant negative correlations were noted between the PLR and SII and baseline HAM-D24 score, signifying that lower systemic inflammation is associated with more severe depressive symptoms. Significant positive correlations were noted between various blood cell ratios and mean time to recovery of orientation in the entire group of patients and in depression subgroups, indicating that increased peripheral inflammation is linked to worse cognitive outcomes post-ECT. Overall, our results suggest that assessment of blood cell ratios could be useful for predicting mood changes in patients at risk of developing depressive episodes or relapse following successful treatment or for identifying those at risk for cognitive side-effects following ECT.