Broad spectrum of cytokine abnormalities in panic disorder and posttraumatic stress disorder

Promising immunomodulators for management of substance and alcohol use disorders

INTRODUCTION

The neuroimmune system has emerged as a novel target for the treatment of substance use disorders (SUDs), with immunomodulation producing encouraging therapeutic benefits in both preclinical and clinical settings.

AREAS COVERED

In this review, we describe the mechanism of action and immune response to methamphetamine, opioids, cocaine, and alcohol. We then discuss off-label use of immunomodulators as adjunctive therapeutics in the treatment of neuropsychiatric disorders, demonstrating their potential efficacy in affective and behavioral disorders. We then discuss in detail the mechanism of action and recent findings regarding the use of ibudilast, minocycline, probenecid, dexmedetomidine, pioglitazone, and cannabidiol to treat (SUDs). These immunomodulators are currently being investigated in clinical trials described herein, specifically for their potential to decrease substance use, withdrawal severity, central and peripheral inflammation, comorbid neuropsychiatric disorder symptomology, as well as their ability to improve cognitive outcomes.

EXPERT OPINION

We argue that although mixed, findings from recent preclinical and clinical studies underscore the potential benefit of immunomodulation in the treatment of the behavioral, cognitive, and inflammatory processes that underlie compulsive substance use.

Retinal changes in generalized anxiety disorder patients

OBJECTIVE

Optical coherence tomography (OCT) is a method that allows high-resolution cross-sectional imaging of biological tissues. It was suggested that changes in the cranial structure or functions would be reflected in the retina. OCT has been an important method in the diagnosis and follow-up of diseases via morphometric or quantitative retinal measurements. Free radicals, inflammatory processes, and neurotransmission disorders play a role in the etiology of generalized anxiety disorder (GAD). The study aimed to demonstrate the retinal changes in GAD patients due to neurodegeneration based on the comparison of the OCT data of the GAD patients and controls, and the differences between OCT findings of GAD patients and those of controls.

METHODS

The study group included 21 GAD patients. The control group included 21 individuals without any known psychiatric or organic disease, including eye diseases.

RESULTS

There was a statistically significant difference between the macular volumes (MV) of the GAD and control groups, the macular volume was lower in the GAD group. There were positive correlations between BDI scores and MV, GCLT, RNFLT-i, RNFLT-n, between BAE scores and (RNFLT-n), and between the CGI severity scale scores and MV, RNFLT-n, and RNFLT-t.

CONCLUSION

OCT analysis of the GAD patients demonstrated that MV values were lower when compared to the control group. Patients with GAD should be screened for these retinal changes. OCT, a simple, non-invasive, and relatively inexpensive method could be employed as a supplementary method in the follow-up of GAD patients.

Exploring the interplay between posttraumatic stress disorder, gut microbiota, and inflammatory biomarkers: a comprehensive meta-analysis

Introduction

Posttraumatic stress disorder (PTSD) is the most common mental health disorder to develop following exposure to trauma. Studies have reported conflicting results regarding changes in immune biomarkers and alterations in the abundance of bacterial taxa and microbial diversity in patients with PTSD.

Aim

The purpose of this meta-analysis is to summarize existing studies examining gut microbiota characteristics and changes in immune biomarkers in patients with PTSD.

Methods

Relevant studies were systematically searched in PubMed, Scopus, and Embase, published in English between January 1, 1960, and December 1, 2023. The outcomes included changes in abundance and diversity in gut microbiota (gut microbiota part) and changes in immune biomarkers (immune part).

Results

The meta-analysis included a total of 15 studies, with 9 focusing on changes in inflammatory biomarkers and 6 focusing on changes in gut microbiota composition in patients with PTSD. No differences were observed between groups for all inflammatory biomarkers (P≥0.05). Two of the six studies found that people with PTSD had less alpha diversity. However, the overall Standardized Mean Difference (SMD) for the Shannon Diversity Index was not significant (SMD 0.27, 95% CI -0.62-0.609, p = 0.110). Regarding changes in abundance, in two of the studies, a significant decrease in Lachnospiraceae bacteria was observed.

Conclusion

This meta-analysis provides a comprehensive overview of gut microbiota characteristics in PTSD, suggesting potential associations with immune dysregulation. Future research should address study limitations, explore causal relationships, and consider additional factors influencing immune function in individuals with PTSD.

Systematic review registration

https://www.crd.york.ac.uk, identifier CRD42023476590.

Preliminary results of anti-inflammatory cytokine concentrations predicting therapy outcome in panic disorder

Background

Patients with panic disorder (PD) show alterations of the immune reactivity to acute stress, which could serve as a marker for effective treatment. Nevertheless, the effect of immune reactivity under acute stress before treatment on therapy outcome remains unclear.

Methods

A total of N = 16 PD patients performed the Trier Social Test. Blood sample collection of anti-inflammatory cytokine IL-10 accompanied the TSST. The Mobility Inventory was handed out for the assessment of avoidance behavior before and after treatment. Area under the curve with respect to the ground (AUCG) and increase (AUCI) were calculated for assessed cytokine levels and were used as predictors for therapy outcome in regression analyses.

Results

AUCG significantly predicts avoidance behavior in company after treatment (β = -0.007, p = .033) but not avoidance behavior alone (β = -0.003, p = .264). AUCI does not significantly predict therapy outcome.

Conclusion

Higher concentrations of anti-inflammatory cytokine IL-10 under acute stress before treatment predicts less avoidance behavior in company after therapy. Immune markers seem to play a crucial role in the maintenance of mental disorders such as PD. Underlying mechanisms and IL-10 as a marker for individualized treatments should be investigated in future studies.

Disentangling the effects of PTSD from Gulf War Illness in male veterans via a systems-wide analysis of immune cell, cytokine, and symptom measures

BACKGROUND

One-third of veterans returning from the 1990-1991 Gulf War reported a myriad of symptoms including cognitive dysfunction, skin rashes, musculoskeletal discomfort, and fatigue. This symptom cluster is now referred to as Gulf War Illness (GWI). As the underlying mechanisms of GWI have yet to be fully elucidated, diagnosis and treatment are based on symptomatic presentation. One confounding factor tied to the illness is the high presence of post-traumatic stress disorder (PTSD). Previous research efforts have demonstrated that both GWI and PTSD are associated with immunological dysfunction. As such, this research endeavor aimed to provide insight into the complex relationship between GWI symptoms, cytokine presence, and immune cell populations to pinpoint the impact of PTSD on these measures in GWI.

METHODS

Symptom measures were gathered through the Multidimensional fatigue inventory (MFI) and 36-item short form health survey (SF-36) scales and biological measures were obtained through cytokine & cytometry analysis. Subgrouping was conducted using Davidson Trauma Scale scores and the Structured Clinical Interview for Diagnostic and statistical manual of mental disorders (DSM)-5, into GWI with high probability of PTSD symptoms (GWIH) and GWI with low probability of PTSD symptoms (GWIL). Data was analyzed using Analysis of variance (ANOVA) statistical analysis along with correlation graph analysis. We mapped correlations between immune cells and cytokine signaling measures, hormones and GWI symptom measures to identify patterns in regulation between the GWIH, GWIL, and healthy control groups.

RESULTS

GWI with comorbid PTSD symptoms resulted in poorer health outcomes compared with both Healthy control (HC) and the GWIL subgroup. Significant differences were found in basophil levels of GWI compared with HC at peak exercise regardless of PTSD symptom comorbidity (ANOVA F = 4.7, P = 0.01,) indicating its potential usage as a biomarker for general GWI from control. While the unique identification of GWI with PTSD symptoms was less clear, the GWIL subgroup was found to be delineated from both GWIH and HC on measures of IL-15 across an exercise challenge (ANOVA F > 3.75, P < 0.03). Additional differences in natural killer (NK) cell numbers and function highlight IL-15 as a potential biomarker of GWI in the absence of PTSD symptoms.

CONCLUSION

We conclude that disentangling GWI and PTSD by defining trauma-based subgroups may aid in the identification of unique GWI biosignatures that can help to improve diagnosis and target treatment of GWI more effectively.

Independent effects of posttraumatic stress disorder diagnosis and metabolic syndrome status on prefrontal cortical thickness and subcortical gray matter volumes

INTRODUCTION

Posttraumatic stress disorder (PTSD) and metabolic syndrome (MetS) are associated with overlapping brain structural differences. These often involve brain structures involved in the regulation of appetite, food intake, satiety, and reward processing. We examined the individual and interactive effects of PTSD diagnosis and MetS on cortical thickness and subcortical gray matter volumes in patients with PTSD (n = 104) compared to trauma-exposed controls (n = 97).

METHODS

Multivariate models were constructed for FreeSurfer-generated prefrontal cortical thickness and subcortical gray matter regions-of-interest (ROIs) to explore the effects of PTSD diagnosis and MetS as predictors, adjusting for relevant socio-demographic and clinical covariates. Individual prefrontal cortical and subcortical limbic ROIs were also selected based on a priori evidence of their involvement in both PTSD and MetS.

RESULTS

The mean age of the sample (n = 201; 78% female) was 41.6 (SD, 13.1) years. PTSD and MetS status showed independent associations with prefrontal cortical thickness and subcortical gray matter volumes across multiple ROIs, adjusting for age, sex, scanner sequence, alcohol, and tobacco use.

CONCLUSIONS

PTSD and MetS are independently associated with brain structural differences, including thinner prefrontal cortical thickness and smaller subcortical gray matter volumes, across multiple ROIs implicated in the hedonic and homeostatic regulation of food intake.

Pediatric Neurocritical Care: Maximizing Neurodevelopmental Outcomes Through Specialty Care

The field of pediatric neurocritical care (PNCC) has expanded and evolved over the last three decades. As mortality from pediatric critical care illness has declined, morbidity from neurodevelopmental disorders has expanded. PNCC clinicians have adopted a multidisciplinary approach to rapidly identify neurological injury, implement neuroprotective therapies, minimize secondary neurological insults, and establish transitions of care, all with the goal of improving neurocognitive outcomes for their patients. Although there are many aspects of PNCC and adult neurocritical care (NCC) medicine that are similar, elemental difference between adult and pediatric medicine has contributed to a divergent evolution of the respective fields. The low incidence of pediatric critical care illness, the heterogeneity of neurological insults, and the limited availability of resources all shape the need for a PNCC clinical care model that is distinct from the established paradigm adopted by the adult neurocritical care community at large. Considerations of neurodevelopment are fundamental in pediatrics. When neurological injury occurs in a child, the neurodevelopmental stage at the time of insult alters the impact of the neurological disease. Developmental variables contribute to a range of outcomes for seemingly similar injuries. Despite the relative infancy of the field of PNCC, early reports have shown that implementation of a specialized PNCC service elevates the quality and safety of care, promotes education and communication, and improves outcomes for children with acute neurological injuries. The multidisciplinary approach of PNCC clinicians and researchers also promotes a culture that emphasizes the importance of quality improvement and education initiatives, as well as development of and adherence to evidence-based guidelines and family-focused care models.

Stress-induced red nucleus attenuation induces anxiety-like behavior and lymph node CCL5 secretion

Previous studies have speculated that brain activity directly controls immune responses in lymphoid organs. However, the upstream brain regions that control lymphoid organs and how they interface with lymphoid organs to produce stress-induced anxiety-like behavior remain elusive. Using stressed human participants and rat models, we show that CCL5 levels are increased in stressed individuals compared to controls. Stress-inducible CCL5 is mainly produced from cervical lymph nodes (CLN). Retrograde tracing from CLN identifies glutamatergic neurons in the red nucleus (RN), the activities of which are tightly correlated with CCL5 levels and anxiety-like behavior in male rats. Ablation or chemogenetic inhibition of RN glutamatergic neurons increases anxiety levels and CCL5 expression in the serum and CLNs, whereas pharmacogenetic activation of these neurons reduces anxiety levels and CCL5 synthesis after restraint stress exposure. Chemogenetic inhibition of the projection from primary motor cortex to RN elicits anxiety-like behavior and CCL5 synthesis. This brain-lymph node axis provides insights into lymph node tissue as a stress-responsive endocrine organ.

Cytokine fluctuation during acute stress is correlated to life trauma

BACKGROUND

Multiple studies have demonstrated that human neurobiology and behavior are inextricably linked to the activity of our immune systems. Trauma is associated with a multitude of immune system changes; reflecting this, posttraumatic stress disorder (PTSD) is often comorbid with immune-related conditions such as autoimmune disorders. To further investigate this phenomenon, we tested our hypothesis that cytokine fluctuations during and after an acute stress response correlates with experienced life trauma.

METHODS

Using a prospective observational approach, this cohort study measured biomarker profiles in firefighter participants (n = 63), with 9 participants having prior PTSD diagnoses and 54 without prior PTSD diagnoses. In addition, life trauma scores were determined from all participants using the Life Events Checklist 5 (LEC-5) survey. Baseline salivary biomarker concentrations were determined, along with levels immediately before, immediately after, and 1 hour following a standardized stressful training event. Biomarkers measured using these salivary samples included 42 cytokines and 6 steroid and thyroid hormones. The concentrations of these markers were then correlated, using Pearson correlation coefficients, with the participants' LEC-5 scores. t Tests were also performed to compare cytokine values between the populations with and without prior PTSD diagnosis.

RESULTS

Included in the cytokine panel were interleukin (IL)-8, IL-10, IL-1B, GCSF, IL1-Ra, Groα, IFNa2, PDGFAA, and VEGF, all of which demonstrated positive correlation at various time points in individuals with increased severity of LEC-5 scores (and thus increased experienced life trauma). Concentrations of Groα, PDGFAA, IL1-Ra, IL-1a, Mip1a, IL-1a, IL-6, Mip1b, TNFα, and TGFα were also found to be significantly altered at various time points in participants with prior PTSD diagnoses, demonstrating some overlap with the LEC-5 Pearson correlations.

CONCLUSION

The results support our hypothesis and demonstrate that LEC-5 scores are indeed significantly correlated to cytokine concentrations and fluctuations surrounding a stress test.

LEVEL OF EVIDENCE

Diagnostic Tests or Criteria; Level IV.

Neuroimmune Mechanisms of Opioid Use Disorder and Recovery: Translatability to Human Studies, and Future Research Directions

Opioid use disorder (OUD) is a major current cause of morbidity and mortality. Long-term exposure to short-acting opioids (MOP-r agonists such as heroin or fentanyl) results in complex pathophysiological changes to neuroimmune and neuroinflammatory functions, affected in part by peripheral mechanisms (e.g., cytokines in blood), and by neuroendocrine systems such as the hypothalamic-pituitary-adrenal (HPA) stress axis. There are important findings from preclinical models, but their role in the trajectory and outcomes of OUD in humans is not well understood. The goal of this narrative review is to examine available data on immune and inflammatory functions in persons with OUD, and to identify major areas for future research. Peripheral blood biomarker studies revealed a pro-inflammatory state in persons with OUD in withdrawal or early abstinence, consistent with available postmortem brain studies (which show glial activation) and diffusion tensor imaging studies (indicating white matter disruptions), with gradual abstinence-associated recovery. The mechanistic roles of these neuroimmune and neuroinflammatory changes in the trajectory of OUD (including recovery and medication management) cannot be examined practically with postmortem data. Collection of longitudinal data in larger-scale human cohorts would allow examination of these mechanisms associated with OUD stage and progression. Given the heterogeneity in presentation of OUD, a precision medicine approach integrating multi-omic peripheral biomarkers and comprehensive phenotyping, including neuroimaging, can be beneficial in risk stratification, and individually optimized selection of interventions for individuals who will benefit, and assessments under refractory therapy.

Alterations in heart rate variability and pro-inflammatory cytokine TNF-alpha in individuals with panic disorder

Based on the autonomic flexibility-neurovisceral integration model, panic disorder (PD) has been associated with a generalized proinflammatory state and lower cardiac vagal tone. The heart rate variability (HRV) provides an index of cardiac autonomic function and reflects the parasympathetic innervation to the heart regulated by the vagus nerve. The aim of this study was to explore the heart rate variability, pro-inflammatory cytokines and their associations in individuals with PD. Short-term HRV with time and frequency domain indices as well as pro-inflammatory cytokines Interleukin-6 (IL-6) and Tumor Necrosis Factor alpha (TNF-alpha) were assessed in seventy individuals with PD (mean age: 35.64 ± 14.21 years) and thirty-three healthy controls (mean age: 38.33 ± 14.14 years). Individuals with PD showed significantly lower HRV in the time and frequency domain parameters during a short-term resting condition. A lower TNF-alpha concentration could be observed in individuals with PD in comparison to healthy controls, but no differences in IL-6. Furthermore, the HRV parameter absolute power in the low-frequency band 0.04-0.15 Hz (LF) predicted TNF-alpha concentrations. In conclusion, a lower cardiac vagal tone, decreased adaptive autonomic nervous system (ANS), and higher pro-inflammatory cytokine state could be observed in individuals with PD compared to healthy controls.

Effect of a slow-paced breathing with heart rate variability biofeedback intervention on pro-inflammatory cytokines in individuals with panic disorder - A randomized controlled trial

A generalized proinflammatory state has been observed in individuals with panic disorder (PD). There is evidence that slow-paced breathing (SPB) with heart rate variability-biofeedback (HRV-BF) strengthens the nervus vagus with its anti-inflammatory pathway. Therefore, with this randomized controlled trial we aimed to investigate the effect of a four-week SPB with HRV-BF intervention on pro-inflammatory cytokines in people with PD. Fifty-five individuals with PD (mean age: 37.22 ± 15.13 years) were randomly allocated either to SPB-HRV-BF (intervention group) or to HRV-Sham-BF (active control group). SPB-HRV-BF was performed over four weeks while cytokine concentration and HRV during a short-term resting condition were measured before and after intervention. SPB-HRV-BF decreased concentration of Tumor Necrosis Factor alpha (TNF-alpha) (F_{(1, 53)} = 4.396, p ≤ .05, η2 = 0.077) in individuals with PD. In addition, SPB-HRV-BF demonstrated an increase in the HRV-time and frequency domain parameters SDNN, Total Power and LF during short-term resting condition. There was no intervention effect in HRV-Sham-BF group. In conclusion, SBP-HRV-BF as a non-pharmacological treatment may reduce pro-inflammatory cytokine TNF-alpha via the cholinergic anti-inflammatory pathway in individuals with PD. Based on the generalized proinflammatory state in PD, decreasing TNF-alpha is highly beneficial to reduce risk of cardiovascular diseases and metabolic syndrome.

Hypophosphatemia, hypokalaemia and rhabdomyolysis associated with a panic attack

Panic attacks have been associated with hypophosphatemia, which can lead to numerous complications if unrecognised. Here, we present the case of an otherwise-healthy man in his 20s who experienced a panic attack accompanied by hypophosphatemia and hypokalaemia and subsequently developed rhabdomyolysis. This trajectory highlights the clinical significance of panic attack-associated metabolic derangements and their potential for medical complications such as rhabdomyolysis.

Metabolic and Inflammatory Response in Post-Traumatic Stress Disorder (PTSD): A Systematic Review on Peripheral Neuroimmune Biomarkers

Several heterogeneous pathophysiology pathways have been hypothesized for being involved in the onset and course of Post-Traumatic Stress Disorder (PTSD). This systematic review aims to summarize the current evidence on the role of inflammation and immunological dysregulations in PTSD, investigating possible peripheral biomarkers linked to the neuroimmune response to stress. A total of 44 studies on the dysregulated inflammatory and metabolic response in subjects with PTSD with respect to controls were included. Eligibility criteria included full-text publications in the English language, human adult samples, studies involving both subjects with a clinical diagnosis of PTSD and a healthy control group. The research was focused on specific blood neuroimmune biomarkers, namely IL-1β, TNF-α, IL-6 and INF-γ, as well as on the potential harmful role of reduced antioxidant activity (involving catalase, superoxide dismutase and glutathione peroxidase). The possible role of the inflammatory-altered tryptophan metabolism was also explored. The results showed conflicting data on the role of pro-inflammatory cytokines in individuals with PTSD, and a lack of study regarding the other mediators investigated. The present research suggests the need for further studies in human samples to clarify the role of inflammation in the pathogenesis of PTSD, to define potential peripheral biomarkers.

Integrated genome-wide methylation and expression analyses provide predictors of diagnosis and early response to antidepressant in panic disorder

BACKGROUND

We investigated differentially methylated and expressed genes between panic disorder (PD) and healthy controls (HCs) to determine whether DNA methylation and expression level of candidate genes can be used as biomarkers for diagnosis and early response.

METHODS

Illumina infiniun Methylation EPIC (850 k) Beadchip for genome-wide methylation screening and mRNA sequencing was conducted in a discovery set (30 patients with PD and 30 matched HCs). The candidate gene loci methylation and expression were verified in an independent validation sample (101 PD patients and 107 HCs).

RESULTS

In the discovery set, there were 3613 differentially methylated cytosine phosphate guanosine sites and these differential methylation positions were located within 1938 unique genes, including 1758 hypermethylated genes, 150 hypomethylated genes, and the coexistence of hypermethylation and hypomethylation sites were found in 30 genes. There were 1111 differential transcripts in PD compared to normal controls (850 down-regulated and 261 up-regulated). Further, 212 differentially expressed genes were screened (40 up-regulated and 172 down-regulated). In the validation set, compared with HCs, there was no significant difference in DNA methylation level of Casitas B-lineage lymphoma (CBL) gene loci (cg07123846). The expression level of CBL gene in PD patients was lower (vs. HCs). After four weeks' treatment, the baseline expression level of CBL gene in the responders was higher than nonresponders.

LIMITATIONS

The sample size was limited. We only chose CBL as a candidate gene. Follow-up periods were short.

CONCLUSIONS

There are differences in genome-wide DNA methylation and mRNA expression between PD patients and HCs. The changes in expression level of CBL gene may be an important molecular marker for PD diagnosis and early response.

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.

Dopamine, Immunity, and Disease

The neurotransmitter dopamine is a key factor in central nervous system (CNS) function, regulating many processes including reward, movement, and cognition. Dopamine also regulates critical functions in peripheral organs, such as blood pressure, renal activity, and intestinal motility. Beyond these functions, a growing body of evidence indicates that dopamine is an important immunoregulatory factor. Most types of immune cells express dopamine receptors and other dopaminergic proteins, and many immune cells take up, produce, store, and/or release dopamine, suggesting that dopaminergic immunomodulation is important for immune function. Targeting these pathways could be a promising avenue for the treatment of inflammation and disease, but despite increasing research in this area, data on the specific effects of dopamine on many immune cells and disease processes remain inconsistent and poorly understood. Therefore, this review integrates the current knowledge of the role of dopamine in immune cell function and inflammatory signaling across systems. We also discuss the current understanding of dopaminergic regulation of immune signaling in the CNS and peripheral tissues, highlighting the role of dopaminergic immunomodulation in diseases such as Parkinson's disease, several neuropsychiatric conditions, neurologic human immunodeficiency virus, inflammatory bowel disease, rheumatoid arthritis, and others. Careful consideration is given to the influence of experimental design on results, and we note a number of areas in need of further research. Overall, this review integrates our knowledge of dopaminergic immunology at the cellular, tissue, and disease level and prompts the development of therapeutics and strategies targeted toward ameliorating disease through dopaminergic regulation of immunity. SIGNIFICANCE STATEMENT: Canonically, dopamine is recognized as a neurotransmitter involved in the regulation of movement, cognition, and reward. However, dopamine also acts as an immune modulator in the central nervous system and periphery. This review comprehensively assesses the current knowledge of dopaminergic immunomodulation and the role of dopamine in disease pathogenesis at the cellular and tissue level. This will provide broad access to this information across fields, identify areas in need of further investigation, and drive the development of dopaminergic therapeutic strategies.

Complementary Approaches for Military Women with Chronic Pelvic Pain: A Randomized Trial

Introduction: Active duty (AD) women suffer with chronic pelvic pain (CPP) while providers tackle diagnoses and treatments to keep them functional without contributing to the opioid epidemic. The purpose of this randomized trial was to determine the effectiveness of noninvasive, self-explanatory mindfulness-based stress reduction (MBSR) or self-paced healthy lifestyle (HL) interventions on CPP in AD women. Methods: A 6-week, interventional prospective study with AD women aged 21-55 years at Mountain Home (MTHM), Idaho, was conducted. Women were randomly assigned to MBSR (N = 21) or HL (N = 20) interventions. The primary outcome was pain perception. The secondary outcomes were depression and circulating cytokine levels. Results: Women in the MBSR group exhibited reduced pain interference (p < 0.01) and depression (p < 0.05) alongside decreased interleukin (IL)-4 (p < 0.05), IL-6 (p < 0.05), eotaxin (p < 0.05), monocyte chemoattractant protein-1 (p = 0.06), and interleukin-1 receptor antagonist (IL-1ra) (p < 0.01) and increased vascular endothelial growth factor (p < 0.05). Women in the HL group did not have changes in pain; however, they did exhibit reduced depression (p < 0.05) alongside decreased granulocyte-macrophage colony-stimulating factor (p < 0.05) and increased tumor necrosis factor alpha (p < 0.05), stromal cell-derived factor-1 (p < 0.01), and IL-1ra (p < 0.01). Conclusions: AD women receiving MBSR or HL had reduced depression scores and altered circulating cytokine levels; however, only those receiving MBSR had reduced pain perception. Findings support MBSR as an effective and viable behavioral treatment for AD women suffering from CPP and provide premise for larger randomized controlled studies. Clinical Trial Registration: MOCHI-An RCT of mindfulness as a treatment for CPP in AD Women NCT04104542 (September 26, 2019).

Selected Biomarkers of Depression: What Are the Effects of Cytokines and Inflammation?

Depression is one of the leading mental illnesses worldwide and lowers the quality of life of many. According to WHO, about 5% of the worldwide population suffers from depression. Newer studies report a staggering global prevalence of 27.6%, and it is rising. Professionally, depression belonging to affective disorders is a psychiatric illness, and the category of major depressive disorder (MDD) comprises various diagnoses related to persistent and disruptive mood disorders. Due to this fact, it is imperative to find a way to assess depression quantitatively using a specific biomarker or a panel of biomarkers that would be able to reflect the patients' state and the effects of therapy. Cytokines, hormones, oxidative stress markers, and neuropeptides are studied in association with depression. The latest research into inflammatory cytokines shows that their relationship with the etiology of depression is causative. There are stronger cytokine reactions to pathogens and stressors in depression. If combined with other predisposing factors, responses lead to prolonged inflammatory processes, prolonged dysregulation of various axes, stress, pain, mood changes, anxiety, and depression. This review focuses on the most recent data on cytokines as markers of depression concerning their roles in its pathogenesis, their possible use in diagnosis and management, their different levels in bodily fluids, and their similarities in animal studies. However, cytokines are not isolated from the pathophysiologic mechanisms of depression or other psychiatric disorders. Their effects are only a part of the whole pathway.

Loneliness in Posttraumatic Stress Disorder: A Neglected Factor in Accelerated Aging?

Prior research suggests that people with Posttraumatic Stress Disorder (PTSD) may experience a form of accelerated biological aging. In other populations, loneliness has been shown to elevate risk for many of the same components of accelerated biological aging, and other deleterious outcomes, as seen in people with PTSD. Although standard diagnostic criteria for PTSD include "feelings of detachment or estrangement from others", the relationship of such feelings to the concept of loneliness remains uncertain, in par potentially due to a failure to distinguish between loneliness versus objective social isolation. In order to catalyze wider research attention to loneliness in PTSD, and the potential contribution to accelerated biological aging, the present paper provides three components: (1) a conceptual overview of the relevant constructs and potential interrelationships, (2) a review of the limited extant empirical literature, and (3) suggested directions for future research. The existing empirical literature is too small to support many definitive conclusions, but there is evidence of an association between loneliness and symptoms of PTSD. The nature of this association may be complex, and the causal direction(s) uncertain. Guided by the conceptual overview and review of existing literature, we also highlight key areas for further research. The ultimate goal of this line of work is to elucidate mechanisms underlying any link between loneliness and accelerated aging in PTSD, and to develop, validate, and refine prevention and treatment efforts.

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.

Pro- and anti-inflammatory cytokines Interleukin-6 and Interleukin-10 predict therapy outcome of female patients with posttraumatic stress disorder

PTSD patients show alterations of the immune system, mainly a 'low-grade inflammation'. Psychotherapeutic treatments are meant to reduce symptom burden of PTSD patients but 30-50% of PTSD patients do not benefit from psychotherapy. Therefore, in this study, the predictive effect of cytokine levels on therapy outcome are investigated. Pro- (IL-6) and anti-inflammatory (IL-10) cytokines in female PTSD patients (N = 17) were assessed under acute stress during a Trier social stress test (TSST) before therapeutic treatment. The predictive effects of IL-6 and IL-10 on therapy outcome (SCL_GSI, BDI) after an inpatient psychotherapeutic treatment at the University Medical Center Carl Gustav Carus, Technische Universität Dresden was investigated. Areas under the curve with respect to ground (AUC_G) and increase (AUC_I) for IL-6 and IL-10 levels during the TSST were calculated and used as predictors in regression analyses with pre-treatment scores. Models including all three predictors show good model fits (R² = 0.255 to 0.744). Models including AUC_G and AUC_I scores show superior fits compared with models including pre-treatment scores alone (ΔR² = 0.196 to 0.444). IL-6 AUC_G and AUC_I scores are significant predictors for post-treatment SCL-GSI and BDI (β = -0.554 to 0.853), whereas IL-10 AUC_G significantly predicts SCL-GSI and BDI (β = -0.449 to -0.509). Therefore, pro- and anti-inflammatory IL-6 and IL-10 levels under acute stress before therapy predict therapy outcome of female PTSD patients regarding general symptom burden and depressive symptoms. Future studies should further address the link between inflammation and therapy outcome, especially underlying mechanisms and influencing factors.

Clenbuterol attenuates immune reaction to lipopolysaccharide and its relationship to anhedonia in adolescents

While inflammation has been implicated in psychopathology, relationships between immune-suppressing processes and psychiatric constructs remain elusive. This study sought to assess whether β2-agonist clenbuterol (CBL) would attenuate immune activation in adolescents with mood and anxiety symptoms following ex vivo exposure of whole blood to lipopolysaccharide (LPS). Our focus on adolescents aimed to target a critical developmental period when psychiatric conditions often emerge and prior to chronicity effects. To capture a diverse range of immunologic and symptomatologic phenotypes, we included 97 psychotropic-medication free adolescents with mood and anxiety symptoms and 33 healthy controls. All participants had comprehensive evaluations and dimensional assessments of psychiatric symptoms. Fasting whole-blood samples were collected and stimulated with LPS in the presence and absence of CBL for 6 hours, then analyzed for 41 cytokines, chemokines, and hematopoietic growth factors. Comparison analyses used Bonferroni-corrected nonparametric tests. Levels of nine immune biomarkers-including IL-1RA, IL-1β, IL-6, IP-10, MCP-1, MIP-1α, MIP-1β, TGF-α, and TNF-α-were significantly reduced by CBL treatment compared to LPS alone. Exploratory factor analysis reduced 41 analytes into 5 immune factors in each experimental condition, and their relationships with psychiatric symptoms were examined as a secondary aim. CBL + LPS Factor 4-comprising EGF, PDGF-AA, PDGF-AB/BB, sCD40L, and GRO-significantly correlated with anticipatory and consummatory anhedonia, even after controlling for depression severity. This study supports the possible inhibitory effect of CBL on immune activation. Using a data-driven method, distinctive relationships between CBL-affected immune biomarkers and dimensional anhedonia were reported, further elucidating the role of β2-agonism in adolescent affective symptomatology.

Stress- and drug-induced neuroimmune signaling as a therapeutic target for comorbid anxiety and substance use disorders

Stress and substance use disorders remain two of the most highly prevalent psychiatric conditions and are often comorbid. While individually these conditions have a debilitating impact on the patient and a high cost to society, the symptomology and treatment outcomes are further exacerbated when they occur together. As such, there are few effective treatment options for these patients, and recent investigation has sought to determine the neural processes underlying the co-occurrence of these disorders to identify novel treatment targets. One such mechanism that has been linked to stress- and addiction-related conditions is neuroimmune signaling. Increases in inflammatory factors across the brain have been heavily implicated in the etiology of these disorders, and this review seeks to determine the nature of this relationship. According to the "dual-hit" hypothesis, also referred to as neuroimmune priming, prior exposure to either stress or drugs of abuse can sensitize the neuroimmune system to be hyperresponsive when exposed to these insults in the future. This review completes an examination of the literature surrounding stress-induced increases in inflammation across clinical and preclinical studies along with a summarization of the evidence regarding drug-induced alterations in inflammatory factors. These changes in neuroimmune profiles are also discussed within the context of their impact on the neural circuitry responsible for stress responsiveness and addictive behaviors. Further, this review explores the connection between neuroimmune signaling and susceptibility to these conditions and highlights the anti-inflammatory pharmacotherapies that may be used for the treatment of stress and substance use disorders.

Retinal Changes in Panic Disorder Patients

AIM

Optical coherence tomography (OCT) is a novel method that allows high resolution cross-sectional imaging of biological tissues. It was suggested that changes in the cranial structure or functions would be reflected in the retina. OCT has been an important method in the diagnosis and follow-up of diseases via morphometric or quantitative retinal measurements. Panic disorder (PD) is an anxiety disorder, where free radicals, inflammatory processes and neurotransmitter transmission disorders play a role in the etiology. The present study aimed to demonstrate neurodegeneration in PD by the comparison of PD patient and control OCT data.

MATERIAL AND METHOD

The study group included 21 PD patients who met the study criteria. The control group included 21 healthy individuals without any known psychiatric or organic disease, including eye disease, and gender-matched to the patient group. All participants underwent detailed psychiatric and eye examinations. Central macular thickness (CMT), macular volume (MV), mean and retinal nerve fiber layer thickness (RNFL), ganglion cell layer thickness (GCLT), and central choroidal thickness (CCT) were measured in both eyes of all participants with OCT. A sociodemographic data form, Clinical Global Impression Scale (CGIS), and Panic Disorder Severity Scale (PDSS) were administered to the participants.

RESULTS

In the study, it was determined that the CMT values of the PD patients were lower when compared to the controls in the OCT examination. There was a statistically significant difference between the CMT of the PD patient group and the control group; the CMT was lower in the patient group. There were no significant differences between the groups based on GCLT, RNFL superior, RNFL inferior, RNFL nasal, RNFL temporal, and CCT. There was no significant correlation between CGIS, PDSS scores and OCT measurements.

CONCLUSION

This is the first study in the literature where patients with a PD diagnosis were analyzed based on the OCT method. OCT, which is a simple, noninvasive and relatively inexpensive method that the patient could easily adapt to during imaging, could be employed as a supplementary method in the diagnosis and follow-up of PD patients.

The association between blast exposure and transdiagnostic health symptoms on systemic inflammation

Chronic elevation of systemic inflammation is observed in a wide range of disorders including PTSD, depression, and traumatic brain injury. Although previous work has demonstrated a link between inflammation and various diagnoses separately, few studies have examined transdiagnostic symptoms and inflammation within the same model. The objective of this study was to examine relationships between psychiatric and health variables and systemic inflammation and to determine whether mild traumatic brain injury (mTBI) and/or exposure to blast munitions moderate these relationships. Confirmatory factor analysis in a large sample (N = 357) of post-9/11 Veterans demonstrated a good fit to a four-factor model reflecting traumatic stress, affective, somatic, and metabolic latent variables. Hierarchical regression models revealed that each of the latent variables were associated with higher levels of systemic inflammation. However, the strongest relationship with inflammation emerged among those who had both war-zone blast exposures and metabolic dysregulation, even after adjusting for mental health latent variables. Exploratory analyses showed that blast exposure was associated with metabolic dysregulation in a dose-response manner, with self-reported closer blast proximity associated with the greatest metabolic dysregulation. Together, these results provide a greater understanding of the types of symptoms most strongly associated with inflammation and underscore the importance of maintaining a healthy lifestyle to reduce the impact of obesity and other metabolic symptoms on future chronic disease in younger to middle-aged Veterans.

Inflammatory and oxidative stress markers in post-traumatic stress disorder: a systematic review and meta-analysis

Post-traumatic stress disorder (PTSD) has been associated with persistent, low-degree inflammation, which could explain the increased prevalence of autoimmune conditions and accelerated aging among patients. The aim of the present study is to assess which inflammatory and oxidative stress markers are associated with PTSD. We carried out a meta-analytic and meta-regression analysis based on a systematic review of studies comparing inflammatory and oxidative stress markers between patients with PTSD and controls. We undertook meta-analyses whenever values of inflammatory and oxidative stress markers were available in two or more studies. Overall, 28,008 abstracts were identified, and 54 studies were included, with a total of 8394 participants. The Newcastle-Ottawa Quality Assessment Scale was used to evaluate the quality of the studies. Concentrations of C-reactive protein (SMD = 0.64; 95% CI: 0.21 to 1.06; p = 0.0031; k = 12), interleukin 6 (SMD = 0.94; 95% CI: 0.36 to 1.52; p = 0.0014; k = 32), and tumor necrosis factor-α (SMD = 0.89; 95% CI: 0.23 to 1.55; p = 0.0080; k = 24) were significantly increased in patients with PTSD in comparison with healthy controls. Interleukin 1β levels almost reached the threshold for significance (SMD = 1.20; 95% CI: -0.04 to 2.44; p = 0.0569; k = 15). No oxidative stress marker was associated with PTSD. These findings may explain why PTSD is associated with accelerated aging and illnesses in which immune activation has a key role, such as cardiovascular diseases and diabetes. In addition, they pointed to the potential role of inflammatory markers as therapeutic targets.

FKBP51 mediates resilience to inflammation-induced anxiety through regulation of glutamic acid decarboxylase 65 expression in mouse hippocampus

Background

Inflammation is a potential risk factor of mental disturbance. FKBP5 that encodes FK506-binding protein 51 (FKBP51), a negative cochaperone of glucocorticoid receptor (GR), is a stress-inducible gene and has been linked to psychiatric disorders. Yet, the role of FKBP51 in the inflammatory stress-associated mental disturbance remained unclear.

Methods

Fkbp5-deficient (Fkbp5-KO) mice were used to study inflammatory stress by a single intraperitoneal injection of lipopolysaccharide (LPS). The anxiety-like behaviors, neuroimaging, immunofluorescence staining, immunohistochemistry, protein and mRNA expression analysis of inflammation- and neurotransmission-related mediators were evaluated. A dexamethasone drinking model was also applied to examine the effect of Fkbp5-KO in glucocorticoid-induced stress.

Results

LPS administration induced FKBP51 elevation in the liver and hippocampus accompanied with transient sickness. Notably, Fkbp5-KO but not wild-type (WT) mice showed anxiety-like behaviors 7 days after LPS injection (LPS-D7). LPS challenge rapidly increased peripheral and central immune responses and hippocampal microglial activation followed by a delayed GR upregulation on LPS-D7, and these effects were attenuated in Fkbp5-KO mice. Whole-brain [¹⁸F]-FEPPA neuroimaging, which target translocator protein (TSPO) to indicate neuroinflammation, showed that Fkbp5-KO reduced LPS-induced neuroinflammation in various brain regions including hippocampus. Interestingly, LPS elevated glutamic acid decarboxylase 65 (GAD65), the membrane-associated GABA-synthesizing enzyme, in the hippocampus of WT but not Fkbp5-KO mice on LPS-D7. This FKBP51-dependent GAD65 upregulation was observed in the ventral hippocampal CA1 accompanied by the reduction of c-Fos-indicated neuronal activity, whereas both GAD65 and neuronal activity were reduced in dorsal CA1 in a FKBP51-independent manner. GC-induced anxiety was also examined, which was attenuated in Fkbp5-KO and hippocampal GAD65 expression was unaffected.

Conclusions

These results suggest that FKBP51/FKBP5 is involved in the systemic inflammation-induced neuroinflammation and hippocampal GR activation, which may contribute to the enhancement of GAD65 expression for GABA synthesis in the ventral hippocampus, thereby facilitating resilience to inflammation-induced anxiety.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02517-8.

Association Between Depression or Anxiety and the Risk of Hepatitis B Flares: A Nationwide Population-Based Cohort Study

Purpose

Depression and anxiety have been reported to increase the risk of infectious diseases and reactivation of latent infection. We conducted a nationwide population-based retrospective cohort study to determine the relationship between hepatitis B flares and depression or anxiety, utilizing outpatient and inpatient data from the Taiwan National Health Insurance Research database collected from 2000 to 2015.

Patients and Methods

A total of 12,992 patients with chronic hepatitis B and newly diagnosed anxiety/depression, without advanced liver disease, were propensity score-matched for age, sex, and comorbidities in a 1:4 ratio to 51,968 controls with chronic hepatitis B without depression/anxiety or advanced liver disease. Both groups were followed-up until December 31, 2015. Cox proportional hazards regression was used to determine the risk factors for hepatitis B flares. The Log rank test and Kaplan-Meier analysis were performed to assess differences in the cumulative incidence of hepatitis B flares according to anxiety/depression status.

Results

The incidence of hepatitis B flares was higher in the depression/anxiety cohort than in the control cohort (log-rank; p < 0.001). Patients with depression/anxiety had a significantly higher incidence rate of hepatitis B flares than those without depression/anxiety (3017 per 105 person-years versus 2042 per 105 person-years, p = 0.003). After adjusting for age and comorbidities, anxiety/depression was independently associated with an increased risk of hepatitis B flares (hazard ratio, 1.173; 95% confidence interval, 1.033-1.277; p = 0.003).

Conclusion

This analysis suggests that in patients with chronic hepatitis B without advanced liver disease, those with concomitant depression or anxiety may be at higher risk of hepatitis B flares.

C-Reactive Protein: Marker of risk for post-traumatic stress disorder and its potential for a mechanistic role in trauma response and recovery

Increasing evidence indicates that inflammation plays a role in PTSD and stress disorder pathophysiology. PTSD is consistently associated with higher circulating inflammatory protein levels. Rodent models demonstrate that inflammation promotes enduring avoidance and arousal behaviors after severe stressors (e.g., predator exposure and social defeat), suggesting that inflammation may play a mechanistic role in trauma disorders. C-reactive protein (CRP) is an innate acute phase reactant produced by the liver after acute infection and chronic disease. A growing number of investigations report associations with PTSD diagnosis and elevated peripheral CRP, CRP gene mutations, and CRP gene expression changes in immune signaling pathways. CRP is reasonably established as a potential marker of PTSD and trauma exposure, but if and how it may play a mechanistic role is unclear. In this review, we discuss the current understanding of immune mechanisms in PTSD with a particular focus on the innate immune signaling factor, CRP. We found that although there is consistent evidence of an association of CRP with PTSD symptoms and risk, there is a paucity of data on how CRP might contribute to CNS inflammation in PTSD, and consequently, PTSD symptoms. We discuss potential mechanisms through which CRP could modulate enduring peripheral and CNS stress responses, along with future areas of investigation probing the role of CRP and other innate immune signaling factors in modulating trauma responses. Overall, we found that CRP likely contributes to central inflammation, but how it does so is an area for further study.

A cross-sectional healthy-control study of serum inflammatory biomarkers interleukin (IL)-1B and IL-2R in panic disorder patients and their offspring

Alterations in the immune system have been associated with a variety of mental illnesses. An increase in circulating inflammatory cytokines is observed not only in people with mental disorders but also in their first-degree relatives. A considerable amount of data support the link between immune system activation and panic disorder (PD) pathogenesis, while it is still unclear whether differential immunological reactivity represents a propensity, a measure of disease activity, or both. To better understand the role of cytokines in PD pathophysiology, we compared the levels of serum inflammatory biomarkers interleukin (IL)-1B and IL-2R among PD patients, offspring of PD patients and healthy controls. The offspring of PD patients were evaluated by a psychiatrist and were considered unaffected by any mental disorder at the time of the evaluation. Concentrations of the cytokines IL-1B and IL-2R were assessed using the Immulite System (Diagnostic Products Corporation). The levels of proinflammatory markers IL-1B and IL-2R were increased in PD patients compared to those of controls, but offspring of PD patients and healthy controls demonstrated no differences regarding peripheral interleukin levels. Our findings suggest that interleukins might represent a disease-dependent marker in PD.

Stress-induced pro- and anti-inflammatory cytokine concentrations in female PTSD and depressive patients

Alterations of the hypothalamus pituitary-axis on one hand and heightened rates of somatic diseases and mortality on the other hand are consistently found for PTSD and MDD patients. A possible link between these factors might be the immune system, in particular pro- and anti-inflammatory cytokines. A 'low-grade inflammation' in PTSD and MDD patients was found, whereas the influence of acute stress and the role of anti-inflammatory cytokines was rarely examined. In this study, 17 female PTSD patients participated in the Trier social stress test while serum cytokine levels (IL-6, IL-10) were assessed. Cytokine levels of PTSD patients were compared with levels of female depressive patients (n = 18) and female healthy controls (n = 18). Group differences were assessed using a 3 (group) x 8 (time: -15, -1, +1, +10, +20, +30, +45, +60 min) ANCOVA for repeated measures with baseline values as covariates. There was no group difference regarding IL-6 levels (p = 0.920) but PTSD patients showed significantly higher levels of IL-10 compared with depressive patients (p < 0.001, d = 0.16) and healthy controls (p = 0.001, d = 0.38). Under acute stress, PTSD patients did not show the widely found elevated IL-6 levels but showed an increase of anti-inflammatory IL-10. Therefore, acute stress seems to promote an imbalance of pro- and anti-inflammatory cytokine levels in PTSD and might indicate a hyperreactive immune response. This should be considered in future studies to further understand the role of the immune system as a link between stress response and somatic diseases.

Posttraumatic Stress Disorder, Myocardial Perfusion, and Myocardial Blood Flow: A Longitudinal Twin Study

BACKGROUND

The link between posttraumatic stress disorder (PTSD) and ischemic heart disease remains elusive owing to a shortage of longitudinal studies with a clinical diagnosis of PTSD and objective measures of cardiac compromise.

METHODS

We performed positron emission tomography in 275 twins who participated in two examinations approximately 12 years apart. At both visits, we obtained a clinical diagnosis of PTSD, which was classified as long-standing (both visit 1 and visit 2), late onset (only visit 2), and no PTSD (no PTSD at both visits). With positron emission tomography, we assessed myocardial flow reserve (MFR), which, in absence of significant coronary stenoses, indexes coronary microvascular function. We compared positron emission tomography data at visit 2 across the three categories of longitudinally assessed PTSD and examined changes between the two visits.

RESULTS

Overall, 80% of the twins had no or minimal obstructive coronary disease. Yet, MFR was depressed in twins with PTSD and was progressively lower across groups with no PTSD (2.13), late-onset PTSD (1.97), and long-standing PTSD (1.93) (p = .01). A low MFR (a ratio <2.0) was present in 40% of the twins without PTSD, in 56% of those with late-onset PTSD, and in 72% of those with long-standing PTSD (p < .001). Associations persisted in multivariable analysis, when examining changes in MFR between visit 1 and visit 2, and within twin pairs. Results were similar by zygosity.

CONCLUSIONS

Longitudinally, PTSD is associated with reduced coronary microcirculatory function and greater deterioration over time. The association is especially noted among twins with chronic, long-standing PTSD and is not confounded by shared environmental or genetic factors.

C-reactive protein is related to a distinct set of alterations in resting-state functional connectivity contributing to a differential pathophysiology of major depressive disorder

BACKGROUND

Several studies in major depressive disorder (MDD) have found inflammation, especially C-reactive protein (CRP), to be consistently associated with MDD and network dysfunction. The aim was to investigate whether CRP is linked to a distinct set of resting-state functional connectivity (RSFC) alterations.

METHODS

For this reason, we investigated the effects of diagnosis and elevated blood plasma CRP levels on the RSFC in 63 participants (40 females, mean age 31.4 years) of which were 27 patients with a primary diagnosis of MDD and 36 healthy control-subjects (HC), utilizing a seed-based approach within five well-established RSFC networks obtained using fMRI.

RESULTS

Of the ten network pairs examined, five showed increased between-network RSFC-values unambiguously connected either to a diagnosis of MDD or elevated CRP levels. For elevated CRP levels, increased RSFC between DMN and AN was found. Patients showed increased RSFC within DMN areas and between the DMN and ECN and VAN, ECN and AN and AN and DAN.

CONCLUSIONS

The results of this study show dysregulated neural circuits specifically connected to elevated plasma CRP levels and independent of other alterations of RSFC in MDD. This dysfunction in neural circuits might in turn result in a certain immune-inflammatory subtype of MDD.

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.

Effect of a Biofeedback Intervention on Heart Rate Variability in Individuals With Panic Disorder: A Randomized Controlled Trial

OBJECTIVE

Some individuals with panic disorder (PD) display reduced heart rate variability (HRV), which may result in an increased risk of cardiovascular mortality. Heart rate variability-biofeedback (HRV-BF) training has been shown to improve the modulation of the autonomic activity. Therefore, this randomized controlled trial was conducted to investigate the effect of a 4-week HRV-BF intervention in individuals with PD. HRV-BF training improved the modulation of the autonomic activity. Therefore, with this randomized controlled trial, we aimed to investigate the effect of a 4-week HRV-BF intervention in people with PD.

METHODS

Thirty-six women and 16 men with PD (mean age = 35.85 [15.60] years) were randomly allocated either to HRV-BF with 0.1-Hz breathing as intervention group or to HRV-Sham-BF as active control group. HRV-BF was performed for 4 weeks, whereas HRV was measured both during a short-term resting condition and during a paced breathing condition before and after intervention.

RESULTS

HRV-BF with 0.1-Hz breathing increased HRV and reduced panic symptoms in individuals with PD. HRV-BF with 0.1-Hz breathing demonstrated an increase in the time and frequency domain parameters of HRV during the short-term resting condition (ΔPost-Pre root mean square successive differences: 5.87 [14.03] milliseconds; ΔPost-Pre standard deviation of all NN intervals: 11.63 [17.06] milliseconds; ΔPost-Pre total power: 464.88 [1825.47] milliseconds2; ΔPost-Pre power in low-frequency range 0.04-0.15 Hz: 312.73 [592.71] milliseconds2), a decrease in the heart rate during the paced breathing condition (ΔPost-Pre: -5.87 [9.14] beats/min), and a decrease in the Panic and Agoraphobia Scale (ΔPost-Pre: -3.64 [6.30]). There was no intervention effect in the HRV-Sham-BF group.

CONCLUSIONS

HRV-BF as a noninvasive and nonpharmacological treatment seems to be an important intervention option to improve reduced HRV and decrease panic symptoms in individuals with PD. Future studies are needed to establish whether these effects translate to reductions in the risk of cardiovascular disease in PD.

Predicting the naturalistic course in anxiety disorders using clinical and biological markers: a machine learning approach

BACKGROUND

Disease trajectories of patients with anxiety disorders are highly diverse and approximately 60% remain chronically ill. The ability to predict disease course in individual patients would enable personalized management of these patients. This study aimed to predict recovery from anxiety disorders within 2 years applying a machine learning approach.

METHODS

In total, 887 patients with anxiety disorders (panic disorder, generalized anxiety disorder, agoraphobia, or social phobia) were selected from a naturalistic cohort study. A wide array of baseline predictors (N = 569) from five domains (clinical, psychological, sociodemographic, biological, lifestyle) were used to predict recovery from anxiety disorders and recovery from all common mental disorders (CMDs: anxiety disorders, major depressive disorder, dysthymia, or alcohol dependency) at 2-year follow-up using random forest classifiers (RFCs).

RESULTS

At follow-up, 484 patients (54.6%) had recovered from anxiety disorders. RFCs achieved a cross-validated area-under-the-receiving-operator-characteristic-curve (AUC) of 0.67 when using the combination of all predictor domains (sensitivity: 62.0%, specificity 62.8%) for predicting recovery from anxiety disorders. Classification of recovery from CMDs yielded an AUC of 0.70 (sensitivity: 64.6%, specificity: 62.3%) when using all domains. In both cases, the clinical domain alone provided comparable performances. Feature analysis showed that prediction of recovery from anxiety disorders was primarily driven by anxiety features, whereas recovery from CMDs was primarily driven by depression features.

CONCLUSIONS

The current study showed moderate performance in predicting recovery from anxiety disorders over a 2-year follow-up for individual patients and indicates that anxiety features are most indicative for anxiety improvement and depression features for improvement in general.

The immune-kynurenine pathway in social anxiety disorder

BACKGROUND

The tryptophan-kynurenine pathway is of major interest in psychiatry and is altered in patients with depression, schizophrenia and panic disorder. Stress and immune alterations can impact this system, through cortisol- and cytokine-induced activation. In addition, there is emerging evidence that the kynurenine pathway is associated with suicidality. There have been no studies to date exploring the immune-kynurenine system in social anxiety disorder (SAD), and indeed very limited human studies on the kynurenine pathway in any clinical anxiety disorder.

METHODS

We investigated plasma levels of several kynurenine pathway markers, including kynurenine (KYN), tryptophan (TRYP) and kynurenic acid (KYNA), along with the KYN/TRYP and KYNA/KYN ratios, in a cohort of 32 patients with SAD and 36 healthy controls. We also investigated a broad array of both basal and lipopolysaccharide (LPS)-stimulated blood cytokine levels including IFN-γ, interleukin (IL)-10, IL-1β, IL-2, IL-4, IL-6, IL-8 and tumor necrosis factor (TNF)-α.

RESULTS

SAD patients had elevated plasma KYNA levels and an increased KYNA/KYN ratio compared to healthy controls. No differences in KYN, TRYP or the KYN/TRYP ratio were seen between the two groups. SAD patients with a history of past suicide attempt showed elevated plasma KYN levels and a higher KYN/TRYP ratio compared to patients without a history of suicide attempt. No differences were seen in basal or LPS-stimulated pro-inflammatory cytokine levels between the patients and controls. However, unstimulated IL-10, an anti-inflammatory cytokine, was significantly lower in the SAD group. A significant sex influence was evident with SAD males having lower levels of IL-10 compared to healthy males but no difference seen between SAD females and healthy females.

CONCLUSIONS

The peripheral kynurenine pathway is altered in SAD and preferentially directed towards KYNA synthesis. Additionally, kynurenine pathway activation, as evidenced by elevated KYN and KYN/TRYP ratio, is evident in SAD patients with a history of past suicide attempt. While no differences in pro-inflammatory cytokines is apparent in SAD patients, lower anti-inflammatory IL-10 levels are seen in SAD males. Further investigation of the role of the immune-kynurenine pathway in SAD and other clinical anxiety disorders is warranted.

Immunomodulatory Role of CB2 Receptors in Emotional and Cognitive Disorders

Emotional behavior, memory, and learning have been associated with alterations in the immune system in neuropsychiatric and neurodegenerative diseases. In recent years, several studies pointed out the involvement of the cannabinoid receptor 2 (CB2r) in the immune system and the regulation of inflammation. This receptor is widely distributed in different tissues and organs with higher expression in spleen and immune system cells. However, CB2r has also been detected in several brain areas and different brain cell types, such as neurons and glia. These findings suggest that CB2r may closely relate the immune system and the brain circuits regulating inflammation, mood, and cognitive functions. Therefore, we review the studies that may help elucidate the molecular bases of CB2r in regulating inflammation in different brain cells and its role in the pathophysiology of psychiatric and neurodegenerative disorders.

New Metabolic, Digestive, and Oxidative Stress-Related Manifestations Associated with Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) represents a pressing and generally invalidating syndrome that is triggered by a terrifying or stressful experience, relying on recurrently reliving the traumatic event feelings associated to it, which is subsequently linked to ongoing activations of stress-related neurobiological pathways and is often associated with neurodegeneration. In this paper, we examine what lies beneath this disorder, reviewing evidence that connects PTSD with a wide array of mechanisms and its intertwined pathways that can lead to the decompensation of different pathologies, such as cardiovascular disease, gastrointestinal ailments, autoimmune disorders, and endocrine diseases. Also, the significance of the oxidative stress in this frame of reference is debated. Thus, knowing and identifying the main features of the distressing experience, the circumstances around it, as well as the neuropsychological and emotional characteristics of people prone to develop PTSD after going through disturbing incidents can offer an opportunity to anticipate the development of potential destructive consequences in several psychological dimensions: cognitive, affective, relational, behavioral, and somatic. We can also observe more closely the intricate connections of the disorder to other pathologies and their underlying mechanisms such as inflammation, oxidative stress, bacterial overgrowth syndrome, irritable bowel syndrome, metabolic disorders, oxytocin, and cortisol in order to understand it better and to optimize the course of treatment and its management. The complex foundation PTSD possesses is supported by the existing clinical, preclinical, and experimental data encompassed in the current review. Different biological systems and processes such as the hypothalamic-pituitary-adrenal axis, sympathetic nervous system, oxidative stress, inflammation, and microbiome suffer modifications and changes when it comes to PTSD; that is why targeted therapies exert tremendous alleviations of symptoms in patients diagnosed with this disorder. Therefore, this implies that PTSD is not restricted to the psychiatric domain and should be viewed as a systemic condition.

Chemokine profile in women with moderate to severe anxiety and depression during pregnancy

Background

Cytokine levels have been extensively described in pregnant subjects under normal and pathological conditions, including mood-related disorders. Concerning chemokines, very few studies have reported their association with psychiatric disorders during pregnancy. Therefore, we explored the chemokine profile in women exhibiting anxiety and depression during late pregnancy in the present study.

Methods

One hundred twenty-six pregnant women in the 3rd trimester of pregnancy, displaying moderate to severe anxiety (ANX) alone and women exhibiting moderate to severe anxiety with comorbid depression (ANX + DEP), and 40 control pregnant women without affective disorders (CTRL) were evaluated through the Hamilton Anxiety Rating Scale (HARS) and the Hamilton Depression Rating Scale (HDRS). Serum chemokine levels of MCP-1 (CCL2), RANTES (CCL5), IP-10 (CXCL10), Eotaxin (CCL11), TARC (CCL17), MIP-1α (CCL3), MIP-1β (CCL4), MIG (CXCL9), MIP-3α (CCL20), ENA-78 (CXCL5), GROα (CXCL1), I-TAC (CXCL11) and IL-8 (CXCL8)] were measured by immunoassay. Clinical, biochemical, and sociodemographic parameters were correlated with HARS and HDRS score values.

Results

Serum levels of most chemokines were significantly higher in the ANX and in the ANX + DEP groups, when compared to the CTRL group. Positive correlations were observed between MIP-1α/CCL3, MIP-1β/CCL4, MCP-1/CCL2, MIP-3α/CCL20, RANTES/CCL5, Eotaxin/CCL11, and I-TAC/CXCL11 with high scores for anxiety (HARS) (p < 0.05) and for depression (HDRS) (p < 0.004). After controlling clinical measures for age + gwk + BMI, chemokines such as IL-8/CXCL8, MCP-1/CCL2 and MIP-1β/CCL4 were found associated with high scores for anxiety (p < 0.05) in the ANX group. TARC/CCL17 and Eotaxin/CCL11 showed significant associations with high scores for depression (p < 0.04) whereas, MCP-1/CCL2 and MIP-1α/CCL3 were significantly associated with high scores for anxiety (p < 0.05) in the ANX + DEP group. Using a multivariate linear model, high serum levels of MIP-1β/CCL4 and Eotaxin/CCL11 remained associated with depression (p < 0.01), while, IL-8/CXCL8, MIP-1β/CCL4, MCP-1/CCL2, and MIP-1α/CCL3 were associated with anxiety (p < 0.05) in the symptomatic groups.

Conclusions

Our data show that serum levels of distinct chemokines are increased in women exhibiting high levels of affective symptoms during late pregnancy. Our results suggest that increased levels of anxiety, depressive symptoms, and mood-related disorders may promote changes in specific functional chemokines associated with a chronic inflammatory process. If not controlled, it may lead to adverse obstetric and negative neonate outcomes, child development and neuropsychiatric alterations in the postnatal life.

Highlights

Chemokine levels increase in affective disorders during pregnancy.

Transcutaneous Cervical Vagal Nerve Stimulation in Patients with Posttraumatic Stress Disorder (PTSD): A Pilot Study of Effects on PTSD Symptoms and Interleukin-6 Response to Stress

BACKGROUND

Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory and sympathetic function, responsible for maintenance of symptoms. Treatment options including medications and psychotherapies have limitations. We previously showed that transcutaneous Vagus Nerve Stimulation (tcVNS) blocks inflammatory (interleukin (IL)-6) responses to stress in PTSD. The purpose of this study was to assess the effects of tcVNS on PTSD symptoms and inflammatory responses to stress.

METHODS

Twenty patients with PTSD were randomized to double blind active tcVNS (N=9) or sham (N=11) stimulation in conjunction with exposure to personalized traumatic scripts immediately followed by active or sham tcVNS and measurement of IL-6 and other biomarkers of inflammation. Patients then self administered active or sham tcVNS twice daily for three months. PTSD symptoms were measured with the PTSD Checklist (PCL) and the Clinician Administered PTSD Scale (CAPS), clinical improvement with the Clinical Global Index (CGI) and anxiety with the Hamilton Anxiety Scale (Ham-A) at baseline and one-month intervals followed by a repeat of measurement of biomarkers with traumatic scripts. After three months patients self treated with twice daily open label active tcVNS for another three months followed by assessment with the CGI.

RESULTS

Traumatic scripts increased IL-6 in PTSD patients, an effect that was blocked by tcVNS (p<.05). Active tcVNS treatment for three months resulted in a 31% greater reduction in PTSD symptoms compared to sham treatment as measured by the PCL (p=0.013) as well as hyperarousal symptoms and somatic anxiety measured with the Ham-A p<0.05). IL-6 increased from baseline in sham but not tcVNS. Open label tcVNS resulted in improvements measured with the CGI compared to the sham treatment period p<0.05).

CONCLUSIONS

These preliminary results suggest that tcVNS reduces inflammatory responses to stress, which may in part underlie beneficial effects on PTSD symptoms.

Influence of the inflammasome complex on psychiatric disorders: clinical and preclinical studies

INTRODUCTION

The innate immune complex, an inflammasome complex, has a role in the etiology of psychiatric disorders. Preclinical studies have demonstrated that the inflammasome activation leads to psychiatric disorders and clinical studies have proved that specific psychiatric illnesses are associated with aberrant levels of inflammatory cytokines and inflammasome. The inflammasome complex could be a major factor in the progression and pathology of psychiatric disorders.

AREA COVERED

We discuss the pathogenesis of psychiatric disorders with respect to the activation of the inflammasome complex. Inflammasome-associated inflammatory cytokines are observed in patients and animal models of psychiatric disorders. The article also reflects on inflammasome regulatory options for the prevention and treatment of psychiatric disorders. Relevant literature available on PubMed from 1992 to 2021 has been included in this review.

EXPERT OPINION

Modulating the inflammasome complex is a potential therapeutic strategy to treat symptom severity for patients with psychiatric disorders, particularly those with inflammasome-associated disorders. However, the nature of the psychiatric disorders should be considered when targeting inflammasome.

Modeling Neuroimmune Interactions in Human Subjects and Animal Models to Predict Subtype-Specific Multidrug Treatments for Gulf War Illness

Gulf War Illness (GWI) is a persistent chronic neuroinflammatory illness exacerbated by external stressors and characterized by fatigue, musculoskeletal pain, cognitive, and neurological problems linked to underlying immunological dysfunction for which there is no known treatment. As the immune system and the brain communicate through several signaling pathways, including the hypothalamic–pituitary–adrenal (HPA) axis, it underlies many of the behavioral and physiological responses to stressors via blood-borne mediators, such as cytokines, chemokines, and hormones. Signaling by these molecules is mediated by the semipermeable blood–brain barrier (BBB) made up of a monocellular layer forming an integral part of the neuroimmune axis. BBB permeability can be altered and even diminished by both external factors (e.g., chemical agents) and internal conditions (e.g., acute or chronic stress, or cross-signaling from the hypothalamic–pituitary–gonadal (HPG) axis). Such a complex network of regulatory interactions that possess feed-forward and feedback connections can have multiple response dynamics that may include several stable homeostatic states beyond normal health. Here we compare immune and hormone measures in the blood of human clinical samples and mouse models of Gulf War Illness (GWI) subtyped by exposure to traumatic stress for subtyping this complex illness. We do this via constructing a detailed logic model of HPA–HPG–Immune regulatory behavior that also considers signaling pathways across the BBB to neuronal–glial interactions within the brain. We apply conditional interactions to model the effects of changes in BBB permeability. Several stable states are identified in the system beyond typical health. Following alignment of the human and mouse blood profiles in the context of the model, mouse brain sample measures were used to infer the neuroinflammatory state in human GWI and perform treatment simulations using a genetic algorithm to optimize the Monte Carlo simulations of the putative treatment strategies aimed at returning the ill system back to health. We identify several ideal multi-intervention strategies and potential drug candidates that may be used to treat chronic neuroinflammation in GWI.

Immune system regulation and role of the human leukocyte antigen in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a debilitating condition that adversely affect mental and physical health. Recent studies have increasingly explored the role of the immune system in risk for PTSD and its related symptoms. Dysregulation of the immune system may lead to central nervous system tissue damage and impair learning and memory processes. Individuals with PTSD often have comorbid inflammatory or auto-immune disorders. Evidence shows associations between PTSD and multiple genes that are involved in immune-related or inflammatory pathways. In this review, we will summarize the evidence of immune dysregulation in PTSD, outlining the contributions of distinct cell types, genes, and biological pathways. We use the Human Leukocyte Antigen (HLA) locus to illustrate the contribution of genetic variation to function in different tissues that contribute to PTSD etiology, severity, and comorbidities.

Importance of sex and trauma context on circulating cytokines and amygdalar GABAergic signaling in a comorbid model of posttraumatic stress and alcohol use disorders

Alcohol use disorder (AUD) and anxiety disorders are frequently comorbid and share mechanisms that could be therapeutic targets. To facilitate mechanistic studies, we adapted an inhibitory avoidance-based "2-hit" rat model of posttraumatic stress disorder (PTSD) and identified predictors and biomarkers of comorbid alcohol (ethanol)/PTSD-like symptoms in these animals. Stressed Wistar rats received a single footshock on two occasions. The first footshock occurred when rats crossed into the dark chamber of a shuttle box. Forty-eight hours later, rats received the second footshock in a familiar (FAM) or novel (NOV) context. Rats then received 4 weeks of two-bottle choice (2BC) ethanol access. During subsequent abstinence, PTSD-like behavior responses, GABAergic synaptic transmission in the central amygdala (CeA), and circulating cytokine levels were measured. FAM and NOV stress more effectively increased 2BC drinking in males and females, respectively. Stressed male rats, especially drinking-vulnerable individuals (≥0.8 g/kg average 2-h ethanol intake with >50% ethanol preference), showed higher fear overgeneralization in novel contexts, increased GABAergic transmission in the CeA, and a profile of increased G-CSF, GM-CSF, IL-13, IL-6, IL-17a, leptin, and IL-4 that discriminated between stress context (NOV > FAM > Control). However, drinking-resilient males showed the highest G-CSF, IL-13, and leptin levels. Stressed females showed increased acoustic startle and decreased sleep maintenance, indicative of hyperarousal, with increased CeA GABAergic transmission in NOV females. This paradigm promotes key features of PTSD, including hyperarousal, fear generalization, avoidance, and sleep disturbance, with comorbid ethanol intake, in a sex-specific fashion that approximates clinical comorbidities better than existing models, and identifies increased CeA GABAergic signaling and a distinct pro-hematopoietic, proinflammatory, and pro-atopic cytokine profile that may aid in treatment.

Effects of celecoxib augmentation of antidepressant or anxiolytic treatment on affective symptoms and inflammatory markers in patients with anxiety disorders: exploratory study

Prolonged stress has been associated with elevated levels of circulating proinflammatory cytokines. Cyclo-oxygenase-2 inhibitors such as celecoxib exert anti-inflammatory effects and may enhance the response to antidepressant drug treatment in patients with depressive disorders, but their effect on anxiety symptoms in patients with anxiety disorders is uncertain. Patients with a primary diagnosis of an anxiety disorder, with stabilised symptoms, underwent either 6 weeks of celecoxib augmentation of continued treatment (n = 18) or continued 'treatment as usual' (n = 9). Assessments included the Warwick-Edinburgh mental well-being Scale (WEMWEBS), Hospital Anxiety and Depression Scale (HADS), Oxford questionnaire of emotional side effects of antidepressants (OQUESA) and Clinical Global Impression of Illness Severity (CGI-S). Venous blood samples were collected for assays of inflammatory cytokines. Patients who underwent celecoxib augmentation showed significant reductions in anxiety (HADS-A -3.17) and depressive (HADS-D -2.11) symptoms and in overall illness severity (CGI-S -1.11), and improvements in mental well-being (WEMWBS 7.5) and positive changes in emotional responsiveness (OQUESA-RP -3.56; OQUESA-AC -4.22): these were not seen with 'treatment as usual'. There were no significant changes in blood levels of inflammatory cytokines in either group. Celecoxib augmentation appeared associated with beneficial effects on anxiety and depressive symptoms and mental well-being. The findings from this pilot study merit further exploration within a double-blind, randomised placebo-controlled study.

Inflammation-driven brain and gut barrier dysfunction in stress and mood disorders

Regulation of emotions is generally associated exclusively with the brain. However, there is evidence that peripheral systems are also involved in mood, stress vulnerability vs. resilience, and emotion‐related memory encoding. Prevalence of stress and mood disorders such as major depression, bipolar disorder, and post‐traumatic stress disorder is increasing in our modern societies. Unfortunately, 30%–50% of individuals respond poorly to currently available treatments highlighting the need to further investigate emotion‐related biology to gain mechanistic insights that could lead to innovative therapies. Here, we provide an overview of inflammation‐related mechanisms involved in mood regulation and stress responses discovered using animal models. If clinical studies are available, we discuss translational value of these findings including limitations. Neuroimmune mechanisms of depression and maladaptive stress responses have been receiving increasing attention, and thus, the first part is centered on inflammation and dysregulation of brain and circulating cytokines in stress and mood disorders. Next, recent studies supporting a role for inflammation‐driven leakiness of the blood–brain and gut barriers in emotion regulation and mood are highlighted. Stress‐induced exacerbated inflammation fragilizes these barriers which become hyperpermeable through loss of integrity and altered biology. At the gut level, this could be associated with dysbiosis, an imbalance in microbial communities, and alteration of the gut–brain axis which is central to production of mood‐related neurotransmitter serotonin. Novel therapeutic approaches such as anti‐inflammatory drugs, the fast‐acting antidepressant ketamine, and probiotics could directly act on the mechanisms described here improving mood disorder‐associated symptomatology. Discovery of biomarkers has been a challenging quest in psychiatry, and we end by listing promising targets worth further investigation.