Physical health and incident late-life depression: modification by cytokine genes

IL-8 (CXCL8) Correlations with Psychoneuroimmunological Processes and Neuropsychiatric Conditions

Interleukin-8 (IL-8/CXCL8), an essential CXC chemokine, significantly influences psychoneuroimmunological processes and affects neurological and psychiatric health. It exerts a profound effect on immune cell activation and brain function, suggesting potential roles in both neuroprotection and neuroinflammation. IL-8 production is stimulated by several factors, including reactive oxygen species (ROS) known to promote inflammation and disease progression. Additionally, CXCL8 gene polymorphisms can alter IL-8 production, leading to potential differences in disease susceptibility, progression, and severity across populations. IL-8 levels vary among neuropsychiatric conditions, demonstrating sensitivity to psychosocial stressors and disease severity. IL-8 can be detected in blood circulation, cerebrospinal fluid (CSF), and urine, making it a promising candidate for a broad-spectrum biomarker. This review highlights the need for further research on the diverse effects of IL-8 and the associated implications for personalized medicine. A thorough understanding of its complex role could lead to the development of more effective and personalized treatment strategies for neuropsychiatric conditions.

Association between increased serum interleukin-8 levels and improved cognition in major depressive patients with SSRIs

BACKGROUND

The effect of neuroinflammatory cytokines on cognitive deficits in patients with major depressive disorder (MDD) can be altered by selective serotonin reuptake inhibitors (SSRIs). This study aimed to examine serum interleukin-8 (IL-8) levels, cognitive function, and their associations in MDD patients with SSRIs.

METHODS

Thirty SSRI-treated MDD patients and 101 healthy controls were recruited for this study. We examined cognitive performance using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and serum IL-8 levels using the Human Inflammatory Cytokine Cytometric Bead Array in both cases and controls.

RESULTS

The RBANS test scores were significantly lower in MDD patients with SSRIs than in healthy controls after controlling for covariates (all p < 0.001). Serum levels of IL-8 were higher in MDD patients with SSRIs than in healthy controls after adjusting for covariates (F = 3.82, p = 0.05). Serum IL-8 levels were positively correlated with sub-scores of delayed memory (r = 0.37, p = 0.04) and visuospatial/constructional (r = 0.43, p = 0.02) in MDD patients with SSRIs but not in in healthy controls (delayed memory score: r = -0.12, p = 0.24; visuospatial/constructional score: r = 0.02, p = 0.81).

CONCLUSIONS

Our findings suggested that increased serum IL-8 level might not only be involved in the MDD psychopathology or the use of SSRIs but also correspond to improving MDD delayed memory and visuospatial/constructional function.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Emotional Regulation Activities Moderates the Risk of Depression in People With Sleep Disturbance: Evidence From a Community Health Survey

Background and Objective It is widely known that poor sleep quality is closely related to depression, but there are limited studies on the mediating factors.Methods Based on national health survey data, the relationship between sleep quality and depressive symptoms was explored, and structural equations were drawn to determine whether emotional regulation activities, such as regular breakfast, regular exercise, smoking, and drinking contribute to poor sleep quality-induced depression.Results There was a significant correlation between poor sleep quality and depressive symptoms. Regular breakfast tended to mediate between poor sleep quality and depression the most, followed by smoking, drinking, and regular exercise.Conclusions Several emotional regulation activities including regular breakfast, can play a protective role in the process leading to poor sleep quality-induced depression. A follow-up study is required to examine the clinical aspect of how regular breakfast can prevent the process of poor sleep quality to depression.

Role of interleukin 8 in depression and other psychiatric disorders

Low grade neuroinflammation has been suggested as one of the underlying mechanisms of many psychiatric diseases as well as cognitive disorders. Interleukin 8 (IL-8), a proinflammatory cytokine produced by many cell types including macrophage and microglia, mainly functions as a neutrophil chemoattractant in the bloodstream. IL-8 is also found in the brain, where it is released from microglia in response to proinflammatory stimuli. In this review, we highlight studies focusing on the role of IL-8 in psychiatric diseases such as major depression, bipolar disorder, schizophrenia, sleep disorder, autism spectrum disorder, anxiety disorders and dementia. Increased peripheral IL-8 levels have been reported in these diseases, particularly in schizophrenic disorder, bipolar disorder, obstructive sleep apnea and autism spectrum disorder. The literature on IL-8 and major depression is inconsistent. IL-8 has been found to be a factor associated with schizophrenic prognosis and therapeutic response, and may affect a wide range of symptomatology. Considering that the exact role of immune alterations is still under research, the success of immune-based therapies in psychiatric diseases is limited for the time being.

Inteurleukin-8 gene variations and the susceptibility to schizophrenia

The relevance of Interleukin-8 (IL-8) cytokine alteration in the peripheral and central system has been widely shown in psychosis while variation in the IL-8 gene remains largely unexplored and to the best of our knowledge, IL-8 polymorphisms have never been specifically targeted in Schizophrenia (Scz). Thus, we set out to search a potential correlation between rs4073, rs2227306 and rs1126647 polymorphisms in IL-8 gene and the development of Scz in a sample of the Tunisian population in a candidate gene approach. Targeted polymorphisms were analysed in 206 patients and 195 controls using PCR-RFLP method. Among all analysed polymorphisms, only rs1126647 showed a significant risk for Scz. After stratification analysis, we noted a significant association of TT genotype and T allele at rs1126647 with paranoid form, and more specifically with female sex. We find that the rare haplotypes at rs4073-rs2227306-rs1126647 of TTT, ACT and TCT, each containing the risk allele rs1126647T, were associated with increased risk for paranoid Scz while only the TCT combination constituted a risk factor for Scz more generally. Our findings support that IL-8 gene may be involved in susceptibility to Scz but this still preliminary and needs to be strengthened by further independent analyses.

Gene-disease association study of tumor necrosis factor-α G-308A gene polymorphism with risk of major depressive disorder: A systematic review and meta-analysis

INTRODUCTION

The single nucleotide polymorphism (SNP) of the tumor necrosis factor-α (TNF-α) G-308A gene is the most studied regarding susceptibility to major depressive disorder (MDD). However, results have been controversial perhaps due to the heterogeneous genetic backgrounds influenced by race as well as subtypes of depression.

METHODS AND MATERIALS

A systematic MEDLINE search was performed to retrieve all published studies that identified the connection between the TNF-α G-308A gene polymorphism and the risk of MDD.

RESULTS

There was no statistical difference between the allele frequencies or genotypes of TNF-α G-308A gene and the depressive patients or healthy subjects in the five models tested. Further, subgroup analyses showed that the TNF-α G-308A gene polymorphism also did not confer susceptibility to poststroke, late-life, maternal, or major depression. Publication bias analysis showed p values were more than .05, suggesting that the 9 articles included in the current analysis had no publication bias.

CONCLUSION

Neither the allele frequencies nor genotypes of TNF-α G-308A gene could be served as an independent risk factor of depression.

Longitudinal associations between glucocorticoid receptor methylation and late-life depression

It has been suggested that hypothalamus-pituitary-adrenal (HPA) axis dysregulation plays a role in the etiology of depression. HPA axis function is mediated by glucocorticoid receptors (GRs), which are influenced by epigenetic mechanisms (DNA methylation). The association between the DNA methylation of the GR gene (nuclear receptor subfamily 3, group C, member 1; NR3C1) and late-life depression as well as the role of NR3C1 methylation in the prediction of the incidence of depression have not yet been investigated. Therefore, we examined the independent and longitudinal effects of the methylation of three CpG sites in exon 1_F of NR3C1 on late-life depression using peripheral blood. In total, 732 Korean community residents aged ≥65 years were assessed; 521 individuals in this group without depression at baseline were followed 2 years later. The Geriatric Mental State Schedule was used to identify depression, and demographic and clinical covariates were evaluated. The effects of NR3C1 methylation (the individual methylation status of three CpG sites and their average values) on current and follow-up depression were calculated using a multivariate logistic regression model. Higher NR3C1 methylation levels at CpG 2 and 3 and the average methylation value were independently associated with the prevalence of depression at baseline. Additionally, a higher NR3C1 methylation level at CpG 2 was associated with depression incidence 2 years later in this population. These findings suggest an association between the methylation of NR3C1 exon 1_F, especially at CpG 2, and depression later in life.

Cytokine Gene Polymorphisms Associated With Symptom Clusters in Oncology Patients Undergoing Radiation Therapy

CONTEXT

Most of the reviews on the biological basis for symptom clusters suggest that inflammatory processes are involved in the development and maintenance of the symptom clusters. However, no studies have evaluated for associations between genetic polymorphisms and common symptom clusters (e.g., mood disturbance, sickness behavior).

OBJECTIVES

Examine the associations between cytokine gene polymorphisms and the severity of three distinct symptom clusters (i.e., mood-cognitive, sickness-behavior, treatment-related) in a sample of patients with breast and prostate cancer (n = 157) at the completion of radiation therapy.

METHODS

Symptom severity was assessed using the Memorial Symptom Assessment Scale. Symptom clusters were created using exploratory factor analysis. The associations between cytokine gene polymorphisms and the symptom cluster severity scores were evaluated using regression analyses.

RESULTS

Polymorphisms in C-X-C motif chemokine ligand 8 (CXCL8), interleukin (IL13), and nuclear factor kappa beta 2 (NFKB2) were associated with severity scores for the mood-cognitive symptom cluster. In addition to interferon gamma (IFNG1), the same polymorphism in NFKB2 (i.e., rs1056890) that was associated with the mood-cognitive symptom cluster score was associated with the sickness-behavior symptom cluster. Polymorphisms in interleukin 1 receptor 1 (IL1R1), IL6, and NFKB1 were associated with severity factor scores for the treatment-related symptom cluster.

CONCLUSION

Our findings support the hypotheses that symptoms that cluster together have a common underlying mechanism and the most common symptom clusters in oncology patients are associated polymorphisms in genes involved in a variety of inflammatory processes.

Impact of Anxiety and Depression on Physical Health Condition and Disability in an Elderly Korean Population

OBJECTIVE

This study aimed to investigate the longitudinal effects of anxiety, depression, and their comorbidity on physical disorders and disability in an elderly Korean population.

METHODS

In total, 1,204 community-dwelling elders were evaluated at baseline, and of these 909 (75%) were re-assessed two years later. Anxiety and depression were identified at baseline using questions from the community version of the Geriatric Mental State diagnostic schedule (GMS-B3). Participants were assessed for functional disability and for 11 physical disorders both at baseline and at follow-up.

RESULTS

Anxiety alone was associated with the incidence of heart disease, depression alone with the incidence of asthma, and comorbid anxiety and depression with incidence of eyesight problem, persistent cough, asthma, hypertension, heart disease, and gastrointestinal problems. Comorbid anxiety and depression were associated with an increase in the number of physical disorders and the degree of disability during the two-year follow-up, compared to anxiety or depression alone or the absence of anxiety or depression.

CONCLUSION

Anxiety, depression, and particularly their comorbidity should be assessed in the elderly population considering their longitudinal effects on physical disorders and disability. Future study is required to determine whether interventions aimed at these disorders can mitigate their impacts.

Genetic Contributions of Inflammation to Depression

This paper describes the effects of immune genes genetic variants and mRNA expression on depression's risk, severity, and response to antidepressant treatment, through a systematic review on all papers published between 2000 and 2016. Our results, based largely on case-control studies, suggest that common genetic variants and gene-expression pathways are involved in both immune activation and depression. The most replicated and relevant genetic variants include polymorphisms in the genes for interleukin (IL)-1β, IL-6, IL-10, monocyte chemoattractant protein-1, tumor necrosis factor-alpha, C-reactive protein, and phospholipase A2. Moreover, increased blood cytokines mRNA expression (especially of IL-1β) identifies patients that are less likely to respond to conventional antidepressants. However, even for the most replicated findings there are inconsistent results, not only between studies, but also between the immune effects of the genetic variants and the resulting effects on depression. We find evidence that these discrepant findings may be explained, at least in part, by the heterogeneity of the depression immunophenotype, by environmental influences and gene × environment interactions, and by the complex interfacing of genetic variants with gene expression. Indeed, some of the most robust findings have been obtained in patients developing depression in the context of treatment with interferon-alpha, a widely used model to mimic depression in the context of inflammation. Further 'omics' approaches, through GWAS and transcriptomics, will finally shed light on the interaction between immune genes, their expression, and the influence of the environment, in the pathogenesis of depression.

Association of TNF-alpha G-308A gene polymorphism with depression: a meta-analysis

BACKGROUND

Although many studies have investigated the association of a single nucleotide polymorphism in TNF-α G-308A gene with depression, their association is still controversial. To clarify this, we performed a meta-analysis.

METHOD

Studies related to TNF-α G-308A and depression were retrieved from PubMed, Medline, Embase, and Scopus (up to April 18, 2017). The odds ratios (ORs) and 95% confidence intervals (CIs) were estimated in the models of allele comparison (G vs A), homozygote comparison (GG vs AA), dominant (GG vs GA + AA), and recessive (GG + GA vs AA) to estimate the strength of the associations.

RESULTS

A total of 10 case-control studies were included in this meta-analysis. Overall, no significant association between TNF-α G-308A and depression was found (G vs A: OR [95% CI] =1.09 [0.92, 1.29]; GG vs AA: 1.24 [0.71, 2.15]; GG vs GA + AA: 1.01 [0.76, 1.35]; GG + GA vs AA: 1.22 [0.70, 2.13]). In subgroup analyses by ethnicity or age group, no statistically significant association between TNF-α G-308A polymorphisms and depression was shown.

CONCLUSION

This meta-analysis revealed that TNF-α G-308A polymorphism is not associated with susceptibility to depression.

Peripheral Inflammatory Parameters in Late-Life Depression: A Systematic Review

Depressive disorders appear relatively frequently in older patients, and therefore represent an important disease burden worldwide. Given the high levels of inflammatory parameters found in depressed elderly patients, the "inflammaging" hypothesis is gaining strength. In this systematic review, we summarize current evidence regarding the relationship between inflammatory parameters and late-life depression, with a unique focus on longitudinal studies to guarantee temporality. According to the data summarized in this review, the levels of some proinflammatory parameters-especially interleukin (IL)-8, IL-6, and tumor necrosis factor (TNF)-α-could serve as biomarkers for the future development of depressive symptoms in elderly patients. Proinflammatory cytokines seem to be associated with the future development of clinically significant depression, irrespective of baseline scores, thus indicating that inflammation temporally precedes and increases depression risk. As insufficient research has been conducted in this field, further prospective studies are clearly warranted.

Anxiety symptoms in Korean elderly individuals: a two-year longitudinal community study

BACKGROUND

Although late-life anxiety occurs frequently and is associated with higher morbidity, few longitudinal studies have been concerned with the evaluation thereof. We investigated the prevalence, incidence, and persistence of anxiety and related factors over a two-year period in community-dwelling Korean elderly individuals.

METHODS

A total of 1,204 Korean elderly individuals were evaluated at baseline, and 909 were followed up two years later. The community version of the Geriatric Mental State Schedule was used to estimate anxiety at both baseline and follow-up interviews. We defined "prevalence" as the rate of anxiety symptoms (for both anxiety cases and sub-threshold anxiety) at baseline; "incidence" as the rate of anxiety symptoms at follow-up in those without baseline anxiety symptoms; and "persistence" as the rate of anxiety symptoms at follow-up in those with baseline anxiety symptoms. Associations between various covariates and anxiety status were examined using multivariate logistic regression models.

RESULTS

The prevalence, incidence, and persistence of anxiety symptoms were 38.1%, 29.3%, and 41.1%, respectively. Prevalent anxiety symptoms were associated independently with female, rented housing, more stressful life event and medical illness, physical inactivity, depression, insomnia, and lower cognitive function. Incident anxiety symptoms were predicted by older age, female gender, depression, and insomnia; persistent anxiety symptoms were predicted by older age, more medical illness, and baseline depression.

CONCLUSIONS

Since depression was associated with prevalent, incident, and persistent anxiety symptoms, effective detection and management thereof is important in older adults to reduce anxiety. Furthermore, preventive collaborative care should be considered, particularly for older, female, insomniac patients.

Interleukin 1B gene (IL1B) variation and internalizing symptoms in maltreated preschoolers

Evidence now implicates inflammatory proteins in the neurobiology of internalizing disorders. Genetic factors may influence individual responses to maltreatment; however, little work has examined inflammatory genetic variants in adults and none in children. The present study examined the role of an interleukin 1B gene (IL1B) variant in preschoolers exposed to maltreatment and other forms of adversity in internalizing symptom development. One hundred ninety-eight families were enrolled, with one child (age 3-5 years) from each family. Adversity measures included child protective service documentation of moderate-severe maltreatment in the last 6 months and interview-assessed contextual stressors. Internalizing symptoms were measured using the Child Behavior Checklist and the Diagnostic Infant and Preschool Assessment. Maltreated children had higher major depressive disorder (MDD) and posttraumatic stress disorder symptoms and marginally higher internalizing symptoms on the Child Behavior Checklist. Controlling for age, sex, and race, IL1B genotype was associated with MDD symptoms (p = .002). Contextual stressors were significantly associated with MDD and posttraumatic stress disorder and marginally with internalizing symptoms. The IL1B genotype interacted with contextual stress such that children homozygous for the minor allele had more MDD symptoms (p = .045). These results suggest that genetic variants of IL1B may modulate the development of internalizing symptoms in the face of childhood adversity.

Comorbidity of depression with physical disorders: research and clinical implications

Depression is prevalent in patients with physical disorders, particularly in those with severe disorders such as cancer, stroke, and acute coronary syndrome. Depression has an adverse impact on the courses of these diseases that includes poor quality of life, more functional impairments, and a higher mortality rate. Patients with physical disorders are at higher risk of depression. This is particularly true for patients with genetic and epigenetic predictors, environmental vulnerabilities such as past depression, higher disability, and stressful life events. Such patients should be monitored closely. To appropriately manage depression in these patients, comprehensive and integrative care that includes antidepressant treatment (with considerations for adverse effects and drug interactions), treatment of the physical disorder, and collaborative care that consists of disease education, cognitive reframing, and modification of coping style should be provided. The objective of the present review was to present and summarize the prevalence, risk factors, clinical correlates, current pathophysiological aspects including genetics, and treatments for depression comorbid with physical disorders. In particular, we tried to focus on severe physical disorders with high mortality rates, such as cancer, stroke, and acute coronary syndrome, which are highly comorbid with depression. This review will enhance our current understanding of the association between depression and serious medical conditions, which will allow clinicians to develop more advanced and personalized treatment options for these patients in routine clinical practice.

Association of BDNF promoter methylation and genotype with suicidal ideation in elderly Koreans

OBJECTIVES

Brain-derived neurotrophic factor (BDNF) has been considered a risk factor for suicidal behavior in adult populations. BDNF secretion is influenced by epigenetic (DNA promoter methylation) and genetic (val66met polymorphism) profiles. We investigated the independent and interactive effects of BDNF methylation status and val66met polymorphisms on late-life suicidal ideation.

METHODS

In total, 732 Korean community residents aged 65+ years were evaluated; of 639 without suicidal ideation, 579 (90.6%) were followed up 2 years later. The prevalence and incidence of suicidal ideation were ascertained using the Geriatric Mental State Schedule. Sociodemographic and clinical covariates included age, sex, education, depressive symptoms, cognitive function, and disability. The independent effects of BDNF methylation status on the prevalence and incidence of suicidal ideation were investigated using multivariate logistic regression models. The two-way interactions of BDNF methylation status and val66met polymorphism on suicidal ideation were assessed using the same models.

RESULTS

Higher BDNF methylation status was significantly associated with both prevalence and incidence of suicidal ideation, independent of potential covariates. No significant methylation-genotype interaction was found.

CONCLUSIONS

The BDNF hypothesis and the epigenetic origin of the suicidal behavior were supported, even in old age. BDNF promoter methylation status may be useful as a biological marker for suicidality in late life.

Inflammatory cytokine-associated depression

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

The potential role of monocyte chemoattractant protein-1 for major depressive disorder

The immune hypothesis of major depressive disorder (MDD) fits well with the supposed interaction between genetic and environmental factors in disorders with a complicated etiopathogenesis. It has been suggested that infectious diseases are associated with MDD in that cytokines may play a critical role as a key modulator in the transition between infection and the development of MDD. It has been also suggested that antidepressants have immunomodulatory effects on some cytokines and cytokine receptors, although the exact mechanism has not yet been fully elucidated. Among cytokines, monocyte chemoattractant protein-1 (MCP-1) is especially well known and has attracted considerable interest owing to its immunomodulatory functions. MCP-1 is expressed in highly regionalized neuronal areas in the brain, leading to kind of modulation of neuronal activity and neuroendocrine functions commonly seen in patients with MDD. Additionally, it is involved in the control of other cytokines that have been consistently proposed as associated with the development of MDD. It also has a possible role in the neurodegenerative process of a number of central nervous system (CNS) diseases. Hence, this paper draws from the perspective of immunology to offer several suggestions about the role of MPC-1 in the development of MDD.