Decreased IFN-γ and IL-12 levels in panic disorder

Evolutionary Aspects of Diverse Microbial Exposures and Mental Health: Focus on "Old Friends" and Stress Resilience

The prevalence of inflammatory disease conditions, including allergies, asthma, and autoimmune disorders, increased during the latter half of the twentieth century, as societies transitioned from rural to urban lifestyles. A number of hypotheses have been put forward to explain the increasing prevalence of inflammatory disease in modern urban societies, including the hygiene hypothesis and the "Old Friends" hypothesis. In 2008, Rook and Lowry proposed, based on the evidence that increased inflammation was a risk factor for stress-related psychiatric disorders, that the hygiene hypothesis or "Old Friends" hypothesis may be relevant to psychiatric disorders. Since then, it has become more clear that chronic low-grade inflammation is a risk factor for stress-related psychiatric disorders, including anxiety disorders, mood disorders, and trauma- and stressor-related disorders, such as posttraumatic stress disorder (PTSD). Evidence now indicates that persons raised in modern urban environments without daily contact with pets, relative to persons raised in rural environments in proximity to farm animals, respond with greater systemic inflammation to psychosocial stress. Here we consider the possibility that increased inflammation in persons living in modern urban environments is due to a failure of immunoregulation, i.e., a balanced expression of regulatory and effector T cells, which is known to be dependent on microbial signals. We highlight evidence that microbial signals that can drive immunoregulation arise from phylogenetically diverse taxa but are strain specific. Finally, we highlight Mycobacterium vaccae NCTC 11659, a soil-derived bacterium with anti-inflammatory and immunoregulatory properties, as a case study of how single strains of bacteria might be used in a psychoneuroimmunologic approach for prevention and treatment of stress-related psychiatric disorders.

Neuroimmune mechanisms in fear and panic pathophysiology

Panic disorder (PD) is unique among anxiety disorders in that the emotional symptoms (e.g., fear and anxiety) associated with panic are strongly linked to body sensations indicative of threats to physiological homeostasis. For example, panic attacks often present with feelings of suffocation that evoke hyperventilation, breathlessness, or air hunger. Due to the somatic underpinnings of PD, a major focus has been placed on interoceptive signaling and it is recognized that dysfunctional body-to-brain communication pathways promote the initiation and maintenance of PD symptomatology. While body-to-brain signaling can occur via several pathways, immune and humoral pathways play an important role in communicating bodily physiological state to the brain. Accumulating evidence suggests that neuroimmune mediators play a role in fear and panic-associated disorders, although this has not been systematically investigated. Currently, our understanding of the role of immune mechanisms in the etiology and maintenance of PD remains limited. In the current review, we attempt to summarize findings that support a role of immune dysregulation in PD symptomology. We compile evidence from human studies and panic-relevant rodent paradigms that indicate a role of systemic and brain immune signaling in the regulation of fear and panic-relevant behavior and physiology. Specifically, we discuss how immune signaling can contribute to maladaptive body-to-brain communication and conditioned fear that are relevant to spontaneous and conditioned symptoms of PD and identify putative avenues warranting future investigation.

Negative correlation between IL-1β, IL-12 and TNF-γ, and cortisol levels in patients with panic disorder

INTRODUCTION

Chronic exposure to stress is a major risk factor in anxiety disorders (ADs) and can be accompanied by an altered microbiome-gut-brain axis and a compromised immune system. In recent years, the study of inflammatory processes in AD has gained special attention. Continued stress causes the reactivity of the hypothalamic-pituitary-adrenal (HPA) axis, the alteration of the intestinal microbiota and the consequent release of pro-inflammatory cytokines, affecting the sensitivity to stress and the similar behavior of anxiety.

METHOD

The aim of the present study was to evaluate the interrelationships between measures of proinflammatory cytokines and cortisol in patients with panic disorder (PD).

RESULTS

The main results of the correlation analysis revealed that the levels of pro-inflammatory cytokines interleukin (IL)-1β, IL-12, and tumor necrosis factor gamma were negatively correlated with cortisol scores (area under the curve with respect to the ground).

CONCLUSIONS

These results suggest that the inflammatory response is associated with the reactivity of the HPA axis in patients with PD and may influence the maintenance of anxiety behavior.

DNA-methylation dynamics across short-term, exposure-containing CBT in patients with panic disorder

Interaction of genetic predispositions and environmental factors via epigenetic mechanisms have been hypothesized to play a central role in Panic Disorder (PD) aetiology and therapy. Cognitive Behavioral Therapy (CBT), including exposure interventions, belong to the most efficient treatments of PD although its biological mechanism of action remains unknown. For the first time, we explored the dynamics and magnitude of DNA-methylation and immune cell-type composition during CBT (n = 38) and the therapeutic exposure intervention (n = 21) to unravel their biological correlates and identify possible biomarkers of therapy success. We report transient regulation of the CD4 + T-Cells, Natural Killers cells, Granulocytes during exposure and a significant change in the proportions of CD4 + T cells, CD8 + T cells and B-Cells and Granulocytes during therapy. In an epigenome-wide association study we identified cg01586609 located in a CpG island and annotated to the serotonin receptor 3 A (HTR3A) to be differentially methylated during fear exposure and regulated at gene expression level with significant differences between remitters and non-remitters (p = 0.028). We moreover report cg01699630 annotated to ARG1 to undergo long lasting methylation changes during therapy (paired t test, genome-wide adj.p value = 0.02). This study reports the first data-driven biological candidates for epigenetically mediated effects of acute fear exposure and CBT in PD patients. Our results provide evidence of changes in the serotonin receptor 3 A methylation and expression during fear exposure associated with different long-term CBT trajectories and outcome, making it a possible candidate in the search of markers for therapy success. Finally, our results add to a growing body of evidence showing immune system changes associated with PD.

Predictive inflammatory biomarkers for change in suicidal ideation in major depressive disorder and panic disorder: A 12-week follow-up study

Previous studies have investigated the role of inflammatory markers in suicidality of patients with major depressive disorder (MDD) or panic disorder (PD). However, few studies have investigated associations between serum inflammatory cytokine levels and suicidality. We hypothesized that MDD and PD status might be significantly associated with serum inflammatory cytokines and that we could predict levels of improvement in suicide ideation intensity using serum inflammatory biomarkers in patients with MDD and PD. For this study, 41 patients with MDD, 52 patients with PD, and 59 healthy control (HC) subjects were enrolled. Psychological measurements and serum inflammatory markers such as interleukin (IL) -6, -10, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and C reactive protein (CRP) were examined. A total of five visits were completed during 12 weeks. After controlling for confounding factors, log-transformed IL-6 (ln_IL-6) at baseline (MDD: 0.297 ± 0.626; PD: 0.342 ± 0.723; HC: -0.121 ± 0.858; p = 0.007, >0.0017, 0.05/30) and mean ln_IL-6 (MDD: 0.395 ± 0.550, PD: 0.249 ± 0.544, HC: -0.139 ± 0.622, p = 0.002, >0.0017, 0.05/30) levels were trends towards significantly higher in patients with MDD and PD than in HC. In MDD patients, a higher level of basal ln_TNF-α was a significant predictor of ΔSSI (changes in SSI scores between baseline and week 12) even after controlling for changes of depression symptoms and baseline SSI scores (standardized β = 0.541, p = 0.002 < 0.0028, 0.05/18). In conclusion, we could predict ΔSSI using baseline inflammatory biomarkers for patients with MDD.

Alterations in Peripheral C-Reactive Protein and Inflammatory Cytokine Levels in Patients with Panic Disorder: A Systematic Review and Meta-Analysis

BACKGROUND

Accumulating evidence has shown the important role of the inflammatory process in the pathophysiology of mental disorders. However, the relative levels of inflammatory markers in patients with panic disorder (PD) have rarely been evaluated. The aim of the present study was to conduct a systematic review to determine the correlation of peripheral C-reactive protein (CRP) and inflammatory cytokine profiles with PD.

METHODS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched for quantitative research studies published up to July 31, 2021 that measured peripheral levels of CRP and inflammatory cytokines in people with PD compared with controls. Meta-analysis using a random-effects model was performed for the levels of CRP and inflammatory cytokines with data from three or more studies.

RESULTS

Fourteen identified studies met the inclusion criteria. In total, 18 cytokines were evaluated. Markers that were reported in more than 3 studies were included in this meta-analysis. The results showed that peripheral levels of CRP, IL-6, IL-2 and TNF-α were significantly higher in PD patients than in healthy controls, while there was no significant difference in peripheral levels of IL-1β, IL-10 and IFN-γ between groups. Notably, the relevant studies involving IL-6, IL-1β, IL-10 and IFN-γ in PD patients were highly heterogeneous. Similar to meta-analyses of other inflammatory factors in mental disorders, our meta-analysis also reflected differences in participant medication use, comorbid anxiety or depression, sampling methods and detection methods. Eight inflammatory cytokines were reported in only one study, and their expression levels were higher, lower, or unchanged compared with those in healthy controls.

CONCLUSION

There is preliminary evidence to suggest a significant inflammatory response in PD patients, but the role of inflammatory markers in PD remains unclear. Studying inflammatory markers in PD will help to clarify the etiology and pathophysiological mechanisms of the disorder.

Role of PPARs in Progression of Anxiety: Literature Analysis and Signaling Pathways Reconstruction

Peroxisome proliferator-activated receptor (PPAR) group includes three isoforms encoded by PPARG, PPARA, and PPARD genes. High concentrations of PPARs are found in parts of the brain linked to anxiety development, including hippocampus and amygdala. Among three PPAR isoforms, PPARG demonstrates the highest expression in CNS, where it can be found in neurons, astrocytes, and glial cells. Herein, the highest PPARG expression occurs in amygdala. However, little is known considering possible connections between PPARs and anxiety behavior. We reviewed possible connections between PPARs and anxiety. We used the Pathway Studio software (Elsevier). Signal pathways were created according to previously developed algorithms. SNEA was performed in Pathway Studio. Current study revealed 14 PPAR-regulated proteins linked to anxiety. Possible mechanism of PPAR involvement in neuroinflammation protection is proposed. Signal pathway reconstruction and reviewing aimed to reveal possible connection between PPARG and CCK-ergic system was conducted. Said analysis revealed that PPARG-dependent regulation of MME and ACE peptidase expression may affect levels of nonhydrolysed, i.e., active CCK-4. Impairments in PPARG regulation and following MME and ACE peptidase expression impairments in amygdala may be the possible mechanism leading to pathological anxiety development, with brain CCK-4 accumulation being a key link. Literature data analysis and signal pathway reconstruction and reviewing revealed two possible mechanisms of peroxisome proliferator-activated receptors involvement in pathological anxiety: (1) cytokine expression and neuroinflammation mechanism and (2) regulation of peptidases targeted to anxiety-associated neuropeptides, primarily CCK-4, mechanism.

Altered immune phenotype and DNA methylation in panic disorder

Background

Multiple studies have related psychiatric disorders and immune alterations. Panic disorder (PD) has been linked with changes in leukocytes distributions in several small studies using different methods for immune characterization. Additionally, alterations in the methylation of repetitive DNA elements, such as LINE-1, have been associated with mental disorders. Here, we use peripheral blood DNA methylation data from two studies and an updated DNA methylation deconvolution library to investigate the relation of leukocyte proportions and methylation status of repetitive elements in 133 patients with panic disorder compared with 118 controls.

Methods and results

We used DNA methylation data to deconvolute leukocyte cell-type proportions and to infer LINE-1 element methylation comparing PD cases and controls. We also identified differentially methylated CpGs associated with PD using an epigenome-wide association study approach (EWAS), with models adjusting for sex, age, and cell-type proportions. Individuals with PD had a lower proportion of CD8T cells (OR: 0.86, 95% CI: 0.78–0.96, P-adj = 0.030) when adjusting for age, sex, and study compared with controls. Also, PD cases had significantly lower LINE-1 repetitive element methylation than controls (P < 0.001). The EWAS identified 61 differentially methylated CpGs (58 hypo- and 3 hypermethylated) in PD (Bonferroni adjusted P < 1.33 × 10^–7).

Conclusions

These results suggest that those with panic disorder have changes to their immune system and dysregulation of repeat elements relative to controls.

DNA methylation of IL-4 gene and the association with childhood trauma in panic disorder

Increasing evidence suggests that aberrations in the immune-inflammatory pathways contribute to the pathophysiology of panic disorder (PD). We aimed to investigate whether an aberrant DNA methylation of the inflammation-related genes in the development of PD, including CCL3, CRP, CSF2, CXCL8, IFNG, IL12B, IL1A, IL-4, IL-6, TNF. Then, the effect of childhood trauma(CT) on methylation levels of  inflammation-related genes and the severity of PD was also investigated. We compared the methylation levels of the inflammation-related genes between 113 patients with PD and 130 matched healthy controls using MethylTarget approach. In addition, the Hamilton Anxiety Rating Scale (HAMA), Panic Disorder Severity Scale (PDSS) and Childhood Trauma Questionnaire-28 item Short Form (CTQ-28) were respectively assessed to all subjects. The result found that the methylation levels of IL-4 gene was significantly higher in PD patients than controls. ROC results found that the IL-4 gene had a sensitivity of 52.3% and a specificity of 74.6%. The methylation levels of IL-4 gene was significantly positively related to the severity of panic and anxiety. Finally, the hypermethylation of CSF2, CXCL8 and IL-4 genes was significantly associated with higher CT.

Differences in cytokines between patients with generalised anxiety disorder and panic disorder

OBJECTIVE

The purpose of this study was to evaluate the differences among panic disorder (PD), generalised anxiety disorder (GAD) and controls in inflammatory cytokines. We also analysed the correlation between inflammatory cytokines and response to escitalopram in PD and GAD patients.

METHODS

Eighty-six patients with PD, 86 patients with GAD and 86 healthy controls were recruited for this study. All participants were, respectively, assessed for severity of anxiety and panic symptoms using the Hamilton Anxiety Rating Scale (HAMA) and the Panic Disorder Severity Scale (PDSS); all patients in the study were also assessed after 4 weeks of treatment. The serum levels of cytokines were measured using a flow fluorescence microsphere assay.

RESULTS

Both PD and GAD patients had higher serum levels of interleukin 6 (IL-6) than controls, and patients with PD showed significantly higher IL-6 than GAD patients. Significant positive correlations were found between the IFN-γ levels and the severity of anxiety in GAD patients. Higher level of IL-6 was associated with better response to escitalopram treatment in PD patients. However, the baseline levels of cytokines were not associated with treatment responses in GAD patients.

CONCLUSION

The present findings suggest that patients with PD may have higher levels of IL-6 than GAD, and higher baseline levels of IL-6 may be a better response to escitalopram in the treatment of PD.

The association between anxiety, traumatic stress, and obsessive-compulsive disorders and chronic inflammation: A systematic review and meta-analysis

BACKGROUND

Anxiety is characterized by prolonged preparation for real or perceived threat. This may manifest both as psychological and physiological activation, ultimately leading to greater risk for poor health. Chronic inflammation may play an integral role in this relationship, given the influential role that it has in chronic illness. The aim of this meta-analysis is to examine levels of chronic inflammation, measured by inflammatory cytokines and C-reactive protein, in people with anxiety disorders, PTSD (posttraumatic stress disorder), or obsessive-compulsive disorder compared to healthy controls. Several moderating variables, including specific diagnosis and depression comorbidity, were also assessed.

METHODS

Seventy six full-text articles were screened for eligibility with 41 studies ultimately included in analysis.

RESULTS

Results demonstrated a significant overall difference between healthy controls (HCs) and people with anxiety disorders in pro-inflammatory cytokines (P = 0.013, Hedge's g = -0.39), which appears to be largely driven by interleukin-1β (IL-1β; P = 0.009, Hedge's g = -0.50), IL-6 (P < 0.001, Hedge's g = -0.93), and tumor necrosis factor-α (P = 0.030, Hedge's g = -0.56). Moderation analyses revealed a moderating effect of diagnosis (P = 0.050), as only individuals with PTSD demonstrated differences in inflammation between HCs (P = 0.004, Hedge's g = -0.68).

CONCLUSIONS

These data demonstrate the association between inflammatory dysregulation and diagnoses associated with chronic, impactful, and severe anxiety and provides insight into the way that anxiety, and in particular PTSD, is related to certain inflammatory markers. In doing so, these findings may provide an initial step in disentangling the relationship between anxiety and basic health processes.

Stress-induced pro- and anti-inflammatory cytokine concentrations in panic disorder patients

BACKGROUND

An attenuated responsivity of the hypothalamus-hypophysis-adrenal (HPA) axis upon challenge and an increased risk for cardiac events are relatively consistent findings in panic disorder (PD) patients. Due to cytokine-HPA interactions, an altered HPA-axis responsivity may be accompanied by altered cytokine concentrations. Immunological reactions under stress might be considered the missing link for explaining an increased cardiac risk. This study analyzed stress-induced cytokine levels in PD patients.

METHODS

A total of n = 32 PD patients and n = 32 healthy control individuals performed the Trier Social Test (TSST). Blood sample collection accompanied the TSST for the collection of cortisol and pro- (IL-6, TNF-α) and anti-inflammatory cytokines (IL-10). Established self-report questionnaires were handed out for the clinical characterization and the assessment of subjective levels of distress during testing. Repeated measures ANCOVA were conducted to evaluate main effects of time or group and time x group interaction effects. Additional ANCOVAS with disease severity as between-subjects factor (healthy, borderline, mild, moderate, severe) took global panic severity into account. Pearson correlation analyses were carried out to test for an association of panic specific symptoms and peak cytokine release.

RESULTS

The TSST resulted in a significantly increased secretion of cortisol, IL-6 and IL-10. The data analysis further revealed a significant time x group interaction effect for cortisol and IL-10. Compared to the healthy volunteers, the PD patients showed significantly higher baseline and challenged IL-10 concentrations but lower challenged cortisol concentrations. Mildly and moderately affected patients showed the highest levels of IL-10 compared to the healthy individuals. There were no differential secretion patterns of IL-6 and TNF-α between both groups in the course of the TSST. The peak IL-6 release was found to be significantly associated with global disease severity.

CONCLUSION

We found evidence for altered levels of cytokines with primarily anti-inflammatory properties in PD patients under baseline and a psychosocial stress condition. The results provide tentative evidence for a low-grade inflammatory process in PD patients, possibly representing a missing link factor between PD diagnosis and the increased risk for cardiac disease.

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.

Evaluation of Oxidant/Antioxidant Status and Cytokine Levels in Patients with Cannabis Use Disorder

Objective

Cannabis is the most commonly used illegal drug in the world and it has several adverse effects such as anxiety, panic reactions and psychotic symptoms. In this study, we aimed to evaluate oxidant, anti-oxidant status and cytokine levels in individuals with cannabis use disorder.

Methods

Thirty-four patients with cannabis use disorder and 34 healthy controls were enrolled to the study. Serum total antioxidant status, total oxidant status and cytokine levels were investigated in patients with cannabis use disorder and healthy controls.

Results

We found increased levels of total oxidant status, oxidative stress index and interleukin (IL) 1β, IL-6, IL-8, and tumor necrosis factor (TNF) α in individuals with cannabis dependency compared to healthy people. When we compared total antioxidant status, IL-12, and interferon (IFN) γ levels, there were no differences in both groups. There was positive correlation between IL-6 and total oxidant status, oxidative stress index levels.

Conclusion

The oxidative balance of individuals with cannabis use disorder was impaired and they had higher levels of IL-1β, IL-6, IL-8, and TNF-α, which is a pro-inflammatory cytokine and indicates increased inflammation compared to healthy controls. Thus, these findings suggest that cannabis increased inflammation and impaired the oxidative balance.

Cytokine Levels in Panic Disorder: Evidence for a Dose-Response Relationship

OBJECTIVE

Several studies have investigated possible biological correlates of mental disorders. Although some studies have consistently reported elevated levels of serum inflammatory markers in depression, very few have evaluated cytokine levels in patients with lifetime panic disorder (PD).

METHODS

Seventy-eight adults (75% women) from an anxiety disorders outpatient unit were categorized according to their PD status: current or in remission. Serum levels of interleukin (IL)-6, tumor necrosis factor α, and IL-10 were evaluated using flow cytometry with enhanced sensitivity flex sets. Data on clinical comorbidity, lipid profile, fasting blood glucose, C-reactive protein, and PD severity were also obtained.

RESULTS

Significantly higher mean levels of serum IL-6 (0.83 vs 0.60 pg/mL [95% confidence interval {CI}for the log-transformed mean difference, -0.41 to -0.57], p = .008) but not of tumor necrosis factor-α (0.18 vs 0.14 pg/mL [95% CI, -1.12 to 0.11]; p = 0.53) or IL-10 (0.21 vs 0.26 [95% CI, -0.20 to 0.44]; p = 0.16), were associated with current PD compared to remitted PD. Higher Panic Disorder Severity Scale (standardized β = 0.36; p = .013), body mass index (standardized β = 0.53, p < .001) and fasting blood glucose 5.6 mmol/L or greater (standardized β = 0.23, p = .038) were significantly associated with higher levels of IL-6 in the multivariate linear regression model.

CONCLUSIONS

Our findings support a proinflammatory state in patients with current PD that is independent of possible confounders. Although there are important implications of these findings, replication is required.

Biological markers for anxiety disorders, OCD and PTSD: A consensus statement. Part II: Neurochemistry, neurophysiology and neurocognition

OBJECTIVE

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part II) summarises findings on potential biomarkers in neurochemistry (neurotransmitters such as serotonin, norepinephrine, dopamine or GABA, neuropeptides such as cholecystokinin, neurokinins, atrial natriuretic peptide, or oxytocin, the HPA axis, neurotrophic factors such as NGF and BDNF, immunology and CO2 hypersensitivity), neurophysiology (EEG, heart rate variability) and neurocognition. The accompanying paper (Part I) focuses on neuroimaging and genetics.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high quality research has accumulated that should improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Cytokine profile and maternal depression and anxiety symptoms in mid-pregnancy-the FinnBrain Birth Cohort Study

Maternal prenatal psychological symptoms are associated with child health outcomes, e.g., atopic diseases. Altered prenatal functioning of the immune system is a potential mechanism linking maternal symptoms with child health. Research on prenatal distress and cytokines is warranted. The study population comprised consecutive N = 139 women from a general population-based FinnBrain Birth Cohort Study. Standardized questionnaires for depressive, overall anxiety, and pregnancy-related anxiety symptoms were used. Serum concentrations of selected cytokines were analyzed using Multiplex bead arrays from samples drawn at the gestational week 24. The concentrations of T helper (Th)2-related interleukins (IL)-9 and IL-13 and Th1-related IL-12 correlated positively with prenatal depressive and overall anxiety symptom scores (p values, range 0.011-0.029). Higher interferon (IFN)-γ/IL-4 ratio (p = 0.039) and Th2-related IL-5 (p = 0.007) concentration correlated positively with depressive symptoms. Pregnancy-related anxiety score correlated positively with IL-12 (p = 0.041), IL-13 (p = 0.025), and anti-inflammatory IL-10 (p = 0.048) concentrations. IL-6 and TNF-α concentrations were unrelated to prenatal symptoms. As a novel finding, we observed positive correlations between concentrations of potentially proallergenic cytokines and maternal prenatal psychological symptoms. Different symptom measures may yield distinct cytokine responses. This provides hypotheses for studies on mechanisms bridging prenatal stress and child health.

Inflammation in Fear- and Anxiety-Based Disorders: PTSD, GAD, and Beyond

The study of inflammation in fear- and anxiety-based disorders has gained interest as growing literature indicates that pro-inflammatory markers can directly modulate affective behavior. Indeed, heightened concentrations of inflammatory signals, including cytokines and C-reactive protein, have been described in posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), panic disorder (PD), and phobias (agoraphobia, social phobia, etc.). However, not all reports indicate a positive association between inflammation and fear- and anxiety-based symptoms, suggesting that other factors are important in future assessments of inflammation's role in the maintenance of these disorders (ie, sex, co-morbid conditions, types of trauma exposure, and behavioral sources of inflammation). The most parsimonious explanation of increased inflammation in PTSD, GAD, PD, and phobias is via the activation of the stress response and central and peripheral immune cells to release cytokines. Dysregulation of the stress axis in the face of increased sympathetic tone and decreased parasympathetic activity characteristic of anxiety disorders could further augment inflammation and contribute to increased symptoms by having direct effects on brain regions critical for the regulation of fear and anxiety (such as the prefrontal cortex, insula, amygdala, and hippocampus). Taken together, the available data suggest that targeting inflammation may serve as a potential therapeutic target for treating these fear- and anxiety-based disorders in the future. However, the field must continue to characterize the specific role pro-inflammatory signaling in the maintenance of these unique psychiatric conditions.

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.

Further evidence for the role of interferon-gamma on anxiety- and depressive-like behaviors: involvement of hippocampal neurogenesis and NGF production

A series of evidence suggests that interferon-gamma (IFN-γ) plays an important role in central nervous system (CNS) functions. However, previous studies have obtained inconsistent results regarding the role of IFN-γ in modulating emotion-related behaviors. The present study aimed to evaluate the behavioral profile of IFN-γ knockout (K.O.) mice in models of anxiety and depression. Male C57Bl6 wild type (WT) or IFN-γ K.O. mice were submitted to the following tests: contextual fear conditioning (CFC), elevated plus maze (EPM), open field (OF) and forced swimming test (FST). To explore the possible neurobiological mechanisms involved, we also assessed hippocampal neurogenesis by means of hippocampal doublecortin expression, and the levels of brain-derived neurothophic factor (BDNF) and nerve growth factor (NGF) in the hippocampus and prefrontal cortex. Our results suggested that IFN-γ K.O. mice exhibited an anxiogenic profile in CFC, EPM and OF tests. In FST, the K.O. group spent more time immobile than the WT group. The number of doublecortin positive cells was reduced in the dentate gyrus, and the expression of NGF was down regulated in the prefrontal cortex of IFN-γ K.O. mice. Our results suggest that IFN-γ is involved in CNS plasticity, contributing to the modulation of anxiety and depressive states.