Interleukin 10 family gene polymorphisms are not associated with major depressive disorder and panic disorder phenotypes

IL-10 (-819C/T), TNFA (-30G/A) and ENOS (-786T/C) Polymorphisms Modulating the Outcome Related to Mental Disorders in Crack Addicted Users

Background

Cocaine/crack use affects immune system molecules and development of mental disorders has been identified.

Objective

To investigate the relationship of polymorphisms in the TNFA (-308G/A), IL-10 (-819C/T) and ENOS (-786T/C) genes with mental disorders in cocaine and crack users.

Methods

A case-control study was carried out, which included 107 cocaine and crack users and 115 controls who never used healthy cocaine and crack. The SNPs in the TNFA (-308G/A), IL-10 (-819C/T) and ENOS (-786T/C) genes were genotyped by real time PCR.

Results

As for the individuals included in this study, the average age of 31.4 years (± 8.59). We identified that the G/A genotype to TNFA (-308) (OR = 0.24; p = 0.03) and the A allele (OR = 0.30; p = 0.03) were associated with reduced risk for dysthymic disorder. The T allele of the IL-10 (-819) polymorphism was associated with decreased risk of developing panic disorder (OR = 0.44; p = 0.01), while the C allele was correlated with an increased risk for alcohol dependence (OR = 1.97; p = 0.04), alcohol abuse (OR = 1.81; p = 0.04) and psychotic syndrome (OR = 2.23; p = 0.01). C/C genotype was correlated with increased chances of developing current psychotic syndrome (OR = 4.23; p = 0.01).

Conclusion

Our results suggest that genetic polymorphisms promote susceptibility or promote protection for clinical phenotypes of psychiatric comorbidities in cocaine and crack users and be considered as good prognostic markers.

Genetic Biomarkers of Panic Disorder: A Systematic Review

(1) Background: Although panic disorder (PD) is one of the most common anxiety disorders severely impacting quality of life, no effective genetic testing exists; known data on possible genetic biomarkers is often scattered and unsystematic which complicates further studies. (2) Methods: We used PathwayStudio 12.3 (Elsevier, The Netherlands) to acquire literature data for further manual review and analysis. 229 articles were extracted, 55 articles reporting associations, and 32 articles reporting no associations were finally selected. (3) Results: We provide exhaustive information on genetic biomarkers associated with PD known in the scientific literature. Data is presented in two tables. Genes COMT and SLC6A4 may be considered the most promising for PD diagnostic to date. (4) Conclusions: This review illustrates current progress in association studies of PD and may indicate possible molecular mechanisms of its pathogenesis. This is a possible basis for data analysis, novel experimental studies, or developing test systems and personalized treatment approaches.

Panic disorders: The role of genetics and epigenetics

Panic disorder is characterized by symptoms with abrupt surges of fear with palpitations, sweating, trembling, heat sensations. Considering its disease burden on each individual and on society, understanding its etiology is important. Though no one specific etiology has been known, like other psychiatric disorders, multiple factors such as genetic, environmental, neurobiological, psychopathological factors have been suggested. In this article, we reviewed currently known etiologies and related study results, regarding especially genetic and epigenetic aspects of the panic disorder. Early studies, including twin studies, family studies, adoption studies suggested highly familial trait of panic disorder. Linkage studies, either, found panic disorder is not a single gene disorder but confirmed existence of multiple related genes. Chromosome and candidate gene studies found few related genes, NPY, ADORA2A, COMT, IKBKE. Newer method, genome-wide association studies (GWAS) have been searching for newer genes. No genome-wide significant genes, however, were detected, confirming previously known candidate genes, NPY5R on 4q31.3-32, BDKRB2 on 14q32, instead. Epigenetic modification has also been studied on many different psychiatric disorders. Monoamine oxidase A (MAOA) hypomethylation, taken together with negative life events, showed relation with panic disorder. Glutamate decarbodylases 1 (GAD1) hypomethylation was also specific on panic disorder patients. Relation with noradrenaline transporter (NET) gene SLC6a2 promoter methylation has also been studied. In conclusion, no specific gene or epigenetic pattern can fully explain etiology of panic disorder. Few genes and epigenetic patterns, however, showed strong association with panic disorder compared to healthy controls. Considering its multivariable background, further studies with larger populations can confirm current results and clarify etiologies of panic disorder.

Cytokine alterations in panic disorder: A systematic review

BACKGROUND

Panic disorder (PD) occurs in 3.4-4.7% of the general population. Although accumulating evidence suggests that some inflammatory processes play a role in the pathophysiology of mental disorders, very few studies have evaluated cytokine levels in patients with PD. The aim of the present study was to systematically review the characteristic cytokine profile of PD patients and discuss some possibilities for future trials on this common and disabling disorder.

METHODS

A comprehensive literature search was carried out in PubMed and Web of Science databases (search terms: "panic disorder" or "panic attacks" and IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, TNF-alpha and INF-gamma).

RESULTS

Eleven studies involving measurements of cytokines in PD patients were included in this review article. Increased serum levels of some inflammatory markers such as IL-6, IL-1β and IL-5 were reported in PD patients compared with control subjects. There are some conflicting results regarding IL-2, IL-12, and INF-γ in association with PD.

LIMITATIONS

There are discrepant findings in the existing literature regarding PD and cytokines. A significant portion of the recognized heterogeneity may be attributable to variability in assay procedures. The discrepant findings may also have been due to differences in the study populations.

CONCLUSIONS

Cytokines induce the production of acute-phase proteins and are linked to neurogenesis, modification of the HPA axis, microglial activation, tryptophan metabolism and an imbalance in excitatory and inhibitory neurotransmission. Investigation of inflammatory biomarkers in PD could contribute to understanding the pathophysiological mechanisms in this debilitating disorder.

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.

The G allele in IL-10-1082 G/A may have a role in lowering the susceptibility to panic disorder in female patients

BACKGROUND

Immune system activation is involved in the pathophysiology of panic disorder (PD). We investigated INF-γ+874 A/T, TNF-α-308 G/A, and IL-10-1082 G/A single nucleotide polymorphisms (SNPs) to determine their association with PD.

METHOD

This study enroled 135 PD patients and 135 healthy controls. INF-γ+874 A/T (rs2430561), TNF-α-308 G/A (rs1800629), and IL-10-1082 G/A (rs1800896) were genotyped.

RESULTS

There were no differences in genotypes or allele frequencies between the patient and control groups, regardless of accompanying agoraphobia. However, for female patients, the G allele frequency in IL-10 SNP was higher in the control group than in the patient group. Additionally, the female control group had a higher frequency of the A/G and G/G genotype in the IL-10 SNP than the female patient group.

CONCLUSION

We suggest that the G allele in IL-10-1082 G/A might have a role in reducing the manifestations of PD in female patients. Further studies are needed to extend and confirm our findings.

Candidate genes in panic disorder: meta-analyses of 23 common variants in major anxiogenic pathways

The utilization of molecular genetics approaches in examination of panic disorder (PD) has implicated several variants as potential susceptibility factors for panicogenesis. However, the identification of robust PD susceptibility genes has been complicated by phenotypic diversity, underpowered association studies and ancestry-specific effects. In the present study, we performed a succinct review of case-control association studies published prior to April 2015. Meta-analyses were performed for candidate gene variants examined in at least three studies using the Cochrane Mantel-Haenszel fixed-effect model. Secondary analyses were also performed to assess the influences of sex, agoraphobia co-morbidity and ancestry-specific effects on panicogenesis. Meta-analyses were performed on 23 variants in 20 PD candidate genes. Significant associations after correction for multiple testing were observed for three variants, TMEM132D rs7370927 (T allele: odds ratio (OR)=1.27, 95% confidence interval (CI): 1.15-1.40, P=2.49 × 10(-6)), rs11060369 (CC genotype: OR=0.65, 95% CI: 0.53-0.79, P=1.81 × 10(-5)) and COMT rs4680 (Val (G) allele: OR=1.27, 95% CI: 1.14-1.42, P=2.49 × 10(-5)) in studies with samples of European ancestry. Nominal associations that did not survive correction for multiple testing were observed for NPSR1 rs324891 (T allele: OR=1.22, 95% CI: 1.07-1.38, P=0.002), TPH1 rs1800532 (AA genotype: OR=1.46, 95% CI: 1.14-1.89, P=0.003) and HTR2A rs6313 (T allele: OR=1.19, 95% CI: 1.07-1.33, P=0.002) in studies with samples of European ancestry and for MAOA-uVNTR in female PD (low-active alleles: OR=1.21, 95% CI: 1.07-1.38, P=0.004). No significant associations were observed in the secondary analyses considering sex, agoraphobia co-morbidity and studies with samples of Asian ancestry. Although these findings highlight a few associations, PD likely involves genetic variation in a multitude of biological pathways that is diverse among populations. Future studies must incorporate larger sample sizes and genome-wide approaches to further quantify the observed genetic variation among populations and subphenotypes of PD.

Does refining the phenotype improve replication rates? A review and replication of candidate gene studies on Major Depressive Disorder and Chronic Major Depressive Disorder

Replication has been poor for previously reported candidate genes involved in Major Depressive Disorder (MDD). One possible reason is phenotypic and genetic heterogeneity. The present study replicated genetic associations with MDD as defined in DSM-IV and with a more narrowly defined MDD subtype with a chronic and severe course. We first conducted a systematic review of genetic association studies on MDD published between September 2007 and June 2012 to identify all reported candidate genes. Genetic associations were then tested for all identified single nucleotide polymorphisms (SNPs) and the entire genes using data from the GAIN genome-wide association study (MDD: n = 1,352; chronic MDD subsample: n = 225; controls: n =  1,649). The 1,000 Genomes database was used as reference for imputation. From 157 studies identified inthe literature, 81 studies reported significant associations with MDD, involving 245 polymorphisms in 97 candidate genes, from which we were able to investigate 185 SNPs in 89 genes. We replicated nine candidate SNPs in eight genes for MDD and six in five genes for chronic MDD. However, these were not more than expected by chance. At gene level, we replicated 18 genes for MDD and 17 genes for chronic MDD, both significantly more than expected by chance. We showed that replication rates were improved for MDD compared to a previous, highly similar, replication study based on studies published before 2007. Effect sizes of the SNPs and replication rates of the candidate genes were improved in the chronic subsample compared to the full sample. Nonetheless, replication rates were still poor.

Polymorphisms of IKBKE gene are associated with major depressive disorder and panic disorder

BACKGROUND

The immune system has been increasingly implicated in the development of mood and anxiety disorders. Inhibitor of kappa light polypeptide gene enhancer in B cells, kinase epsilon (IKBKE) gene encodes IKKε protein that is involved in innate immunity, predominantly antiviral response generation. It also bears pro-inflammatory properties that could affect psychiatric outcomes. In order to investigate the possible role of IKBKE gene in major depressive disorder (MDD) and panic disorder (PD), we conducted a case-control genetic association study concerning these disorders.

METHODS

In all, 14 SNPs of IKBKE gene were genotyped in groups of 391 patients with MDD and 190 patients with PD together with respective 389 and 371 healthy control individuals. The given groups were further divided by gender for additional analyses.

RESULTS

Substantial genetic associations were revealed between IKBKE SNPs and MDD (multiple testing adjusted P < 0.05) and suggestive associations in case of PD (P(adj) > 0.05). In addition, two SNPs that were only associated with PD among males, also displayed significantly different allele frequencies compared to PD females. This may indicate a specific role of these SNPs in male PD, but caution should be applied here due to the small size of the studied PD males group.

CONCLUSIONS

The results of this study confirm our initial findings and indicate a possible role of IKBKE gene in mood and anxiety disorders.

Fibroblasts from patients with major depressive disorder show distinct transcriptional response to metabolic stressors

Major depressive disorder (MDD) is increasingly viewed as interplay of environmental stressors and genetic predisposition, and recent data suggest that the disease affects not only the brain, but the entire body. As a result, we aimed at determining whether patients with major depression have aberrant molecular responses to stress in peripheral tissues. We examined the effects of two metabolic stressors, galactose (GAL) or reduced lipids (RL), on the transcriptome and miRNome of human fibroblasts from 16 pairs of patients with MDD and matched healthy controls (CNTR). Our results demonstrate that both MDD and CNTR fibroblasts had a robust molecular response to GAL and RL challenges. Most importantly, a significant part (messenger RNAs (mRNAs): 26-33%; microRNAs (miRNAs): 81-90%) of the molecular response was only observed in MDD, but not in CNTR fibroblasts. The applied metabolic challenges uncovered mRNA and miRNA signatures, identifying responses to each stressor characteristic for the MDD fibroblasts. The distinct responses of MDD fibroblasts to GAL and RL revealed an aberrant engagement of molecular pathways, such as apoptosis, regulation of cell cycle, cell migration, metabolic control and energy production. In conclusion, the metabolic challenges evoked by GAL or RL in dermal fibroblasts exposed adaptive dysfunctions on mRNA and miRNA levels that are characteristic for MDD. This finding underscores the need to challenge biological systems to bring out disease-specific deficits, which otherwise might remain hidden under resting conditions.

Evidence for Association between the Brain-Derived Neurotrophic Factor Gene and Panic Disorder: A Novel Haplotype Analysis

OBJECTIVE

Panic disorder (PD) is a common psychiatric disorder with a complex etiology, and several studies have suggested that it has a genetic component. Brain-derived neurotrophic factor (BDNF) is the most abundant of the neurotrophins in the brain and is recognized for its important role in the survival, differentiation and growth of neurons. Several lines of research have suggested possible associations between the BDNF gene and PD. In this study, we investigated the BDNF 196G/A (rs6265), 11757G/C (rs16917204), and 270C/T (rs56164415) single nucleotide polymorphisms (SNPs) in order to determine an association with PD. We also identified the genetic sequence associations with PD via haplotype analysis.

METHODS

Participants in this study included 136 PD patients and 263 healthy controls. Male and female subjects were analyzed separately. The genotype and allele frequencies of the PD patients and controls were analyzed using χ(2) statistics. Frequencies and haplotype reconstructions were calculated using the SNP analyzer 2.0.

RESULTS

We found no significant statistical differences in the genotype distributions or allele frequencies of the three tested polymorphisms between the PD and control groups. In addition, no differences were found between PD patients and the controls in either male or female subgroups. However, we found that, the frequency of the G-C haplotype for 196G/A and 11757G/C was significantly higher in PD patients than in the controls.

CONCLUSION

Our result suggest that patients with the G-C haplotype for 196G/A and 11757G/C may be more susceptible to the development of PD. Further studies are needed to replicate the associations that we observed.

The role of immune genes in the association between depression and inflammation: a review of recent clinical studies

The role for dysregulation of the immune system in the pathogenesis of depressive disorder is well established, and emerging research suggests the role of an underlying genetic vulnerability. The purpose of this review is to summarize the existing literature on the genetic variants involved in neurobiological pathways associated with both immune activation and depression. Using PubMed, Scopus, The Cochrane Library, Embase, Ovid of Medline, PsycINFO and ISI web of Knowledge, we selected 52 papers which are relevant for this literature review. Findings across the literature suggest that functional allelic variants of genes for interleukin-1beta (IL)-1β, tumor necrosis factor-alpha (TNF-α) and C-reactive protein (CRP), as well as genetic variations affecting T-cell function, may increase the risk for depression. Moreover, single nucleotide polymorphisms (SNPs) in the IL-1β, IL-6 and IL-11 genes, and in those regulating T-cell function may be associated with reduced responsiveness to antidepressant therapy. There is also some evidence indicative of a role of genetic variants of the enzymes, Cyclo-oxygenase2 (COX-2) and Phospholipase2 (PLA2), in the aetiology of depression. Finally, SNPs in genes related to the serotonin pathway may play a fundamental role in the shared genetic liability to both immune activation and depressive symptoms. Our review confirms that genetic variants influence the biological mechanisms by which the innate immune system contributes to the development of depression. However, future studies are necessary to identify the molecular mechanisms underlying these associations.

A genetic predisposition to produce low levels of IL-10 is related to depressive symptoms: a pilot study of patients with end stage renal disease

OBJECTIVE

Heightened levels of inflammation may be associated with an increased risk of depression, particularly among those with inflammatory medical conditions. Although elevated rates of both systemic inflammation and depression have been documented among patients with end stage renal disease (ESRD), the link between these factors has received little empirical evaluation. The goal of this pilot study was to investigate the association between cytokine gene polymorphisms (that are known to influence pro- and anti-inflammatory cytokine production) and depressive symptoms among patients with ESRD.

METHODS

Ninety-three patients with ESRD completed the Beck Depression Inventory-II and the disease-related symptom subscale of the Kidney Disease Quality of Life short form. Patients were genotyped for eight single nucleotide polymorphisms in genes coding for pro-inflammatory (TNF-α, IL-6, IFN-γ) and anti-inflammatory (IL-10, TGF-β1) cytokines.

RESULTS

Regression analyses indicated that patients with the A/A genotype for the IL-10 -1082 polymorphism (lower IL-10 producers) reported significantly greater depressive symptoms than G allele carriers (higher IL-10 producers; b = 0.22, P = 0.011), even after controlling for relevant covariates.

CONCLUSION

These findings provide some support for cytokine theories of depression in the medically ill, and specifically for the protective role of anti-inflammatory processes. Further research is needed to confirm these preliminary results and to explore the possibility of identifying subtypes of depressed patients based on inflammatory profiles, and those who may benefit from anti-inflammatory therapies.

Promoter variants in IL18 are associated with onset of depression in patients previously exposed to stressful-life events

BACKGROUND

Depression is accompanied by an inflammatory reaction and activation of cell mediated immunity (CMI) and stressors may induce the cytokine network in humans. The proinflammatory cytokine interleukin-18 (IL-18) is less investigated in depression but highly relevant since it is produced by activated macrophages and expressed in the brain.

METHODS

The distribution of six polymorphisms in IL10, IL18 and NF was compared between patients with a single episode of depression either preceded by a stressful life event (n=182), or occurring without a prior stressful life event (n=106) and a group of healthy control individuals (n=335).

RESULTS

The major C allele of the IL18 rs187238 and the major G allele of rs1946518 had a significantly higher prevalence among the patients with a stressful life event prior to onset of disease than both patients without a stressful life event and compared with the healthy controls individuals. None of the examined IL10 or NF alleles were differently distributed among these groups.

LIMITATIONS

Data are nominally significant and not resistant to correction for multiple testing.

CONCLUSION

The major C allele of the IL18 rs187238 and the major G allele rs1946518 have previously been associated with higher expression of IL-18 mRNA. Our data suggest that this genetic trend towards higher IL-18 production may increase the susceptibility to depression in response to stressful life events.