Anterior insula morphology and vulnerability to psychopathology-related symptoms in response to acute inflammation

LPS-induced whole-blood cytokine production and depressive symptoms in dementia spousal caregivers: The moderating effect of childhood trauma

Dementia spousal caregivers are at risk for adverse mental and physical health outcomes. Caregiver burden, anticipatory grief, and proinflammatory cytokine production may contribute to depressive symptoms among caregivers. People who report childhood trauma are more likely to have exaggerated stress responses that may also contribute to depressive symptoms in adulthood. This study aimed to test whether the relationship between whole-blood cytokine production and depressive symptoms is strongest in caregivers who report high levels of childhood trauma.

METHODS

A sample of 103 dementia spousal caregivers provided self-report data on demographics, health information, caregiver burden, anticipatory grief, and depressive symptoms. We also determined lipopolysaccharide-induced whole-blood cytokine production as the primary measure of immune cell reactivity. We measured interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) and converted z-scores of each cytokine into a composite panel. We regressed depressive symptoms on proinflammatory cytokine production, caregiver burden, and anticipatory grief, adjusting for demographic and health-related covariates.

RESULTS

Whole-blood cytokine production and childhood trauma were associated with depressive symptoms. Childhood trauma moderated the relationship between whole-blood cytokine production and depressive symptoms. Whole-blood cytokine production was only associated with depressive symptoms at mean and high levels of childhood trauma, but not at low levels of childhood trauma. The main effects of burden and anticipatory grief on depressive symptoms were strongest for caregivers reporting high levels of childhood trauma.

DISCUSSION

Childhood trauma has lasting impacts on psychosocial experiences later in life and has effects that may confer susceptibility to inflammation-related depression. Our findings contribute to ongoing efforts to identify risk factors for adverse mental health in dementia spousal caregivers.

The role of the immune system in depersonalisation disorder

OBJECTIVES

Depersonalisation-derealization disorder (DPD) is a dissociative disorder that impairs cognitive function and occupational performance. Emerging evidence indicate the levels of tumour necrosis factor-α and interleukin associated with the dissociative symptoms. In this study, we aimed to explore the role of the immune system in the pathology of DPD.

METHODS

We screened the protein expression in serum samples of 30 DPD patients and 32 healthy controls. Using a mass spectrometry-based proteomic approach, we identified differential proteins that were verified in another group of 25 DPD patients and 30 healthy controls using immune assays. Finally, we performed a correlation analysis between the expression of differential proteins and clinical symptoms of patients with DPD.

RESULTS

We identified several dysregulated proteins in patients with DPD compared to HCs, including decreased levels of C-reactive protein (CRP), complement C1q subcomponent subunit B, apolipoprotein A-IV, and increased levels of alpha-1-antichymotrypsin (SERPINA3). Moreover, the expression of CRP was positively correlated with visuospatial memory and the ability to inhibit cognitive interference of DPD. The expression of SERPINA3 was positively correlated with the ability to inhibit cognitive interference and negatively correlated with the perceptual alterations of DPD.

CONCLUSIONS

The dysregulation of the immune system may be the underlying biological mechanism in DPD. And the expressions of CRP and SERPINA3 can be the potential predictors for the cognitive performance of DPD.

Implications of Inflammatory Processes on a Developing Central Nervous System in Childhood-Onset Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that is increasingly affecting pediatric and adult populations. Neuropsychiatric manifestations (ie, cognitive dysfunction and mood disorders) appear to occur with greater severity and poorer prognosis in childhood-onset SLE (cSLE) versus adult-onset SLE, negatively impacting school function, self-management, and psychosocial health, as well as lifelong health-related quality of life. In this review, we describe pathogenic mechanisms active in cSLE, such as maladaptive inflammatory processes and ischemia, which are hypothesized to underpin central phenotypes in patients with cSLE, and the role of alterations in protective central nervous system (CNS) barriers (ie, the blood-brain barrier) are also discussed. Recent findings derived from novel neuroimaging approaches are highlighted because the methods employed in these studies hold potential for identifying CNS abnormalities that would otherwise remain undetected with conventional multiple resonance imaging studies (eg, T2-weighted or fluid-attenuated inversion recovery sequences). Furthermore, we propose that a more robust presentation of neuropsychiatric symptoms in cSLE is in part due to the harmful impact of a chronic inflammatory insult on a developing CNS. Although the immature status of the CNS may leave patients with cSLE more vulnerable to harboring neuropsychiatric manifestations, the same property may represent a greater urgency to reverse the maladaptive effects associated with a proneuroinflammatory state, provided that effective diagnostic tools and treatment strategies are available. Finally, considering the crosstalk among the CNS and other organ systems affected in cSLE, we postulate that a finer understanding of this interconnectivity and its role in the clinical presentation in cSLE is warranted.

Mobilization of the innate immune response by a specific immunostimulant β-glucan confers resistance to chronic stress-induced depression-like behavior by preventing neuroinflammatory responses

Pre-stimulation of the innate immune response is an effective strategy to prevent depression-like phenotypes in animals. However, the use of conventional immunostimulants may cause adverse effects. Therefore, the search for agents that stimulate the innate immune response but do not induce a pro-inflammatory response could be a new research direction for the prevention of depression. β-glucan is a polysaccharide from Saccharomyces cerevisiae with unique immunomodulatory activity in microglia without eliciting a pro-inflammatory response that could lead to tissue damage. This suggests that β-glucan may be a suitable drug that can be used to prevent depression-like phenotypes. Our results showed that a single injection of β-glucan 1 day before stress exposure at a dose of 10 or 20 mg/kg, but notat a dose of 5 mg/kg, prevented depression-like behavior in mice treated with chronic unpredictable stress (CUS). This effect of β-glucan disappeared when the time interval between β-glucan and stress was extended from 1 day or 5 days to 10 days, which was rescued by a second injection 10 days after the first injection or by a repeated injection (4×, once daily) 10 days before stress exposure. A single β-glucan injection (20 mg/kg) 1 day before stress exposure prevented the CUS-induced increase in brain pro-inflammatory cytokines, and inhibition of the innate immune response by minocycline (40 mg/kg) abolished the preventive effect of β-glucan on CUS-induced depression-like behaviors and neuroinflammatory responses. These results suggest that β-glucan may prevent chronic stress-induced depression-like phenotypes and neuroinflammatory responses by stimulating the innate immune response.

Immunoception: the insular cortex perspective

To define the systemic neuroimmune interactions in health and disease, we recently suggested immunoception as a term that refers to the existence of bidirectional functional loops between the brain and the immune system. This concept suggests that the brain constantly monitors changes in immune activity and, in turn, can regulate the immune system to generate a physiologically synchronized response. Therefore, the brain has to represent information regarding the state of the immune system, which can occure in multiple ways. One such representation is an immunengram, a trace that is partially stored by neurons and partially by the local tissue. This review will discuss our current understanding of immunoception and immunengrams, focusing on their manifestation in a specific brain region, the insular cortex (IC).

Endotoxin-Induced Physiological and Psychological Sickness Responses in Healthy Humans: Insights into the Post-Acute Phase

INTRODUCTION

Experimental endotoxemia is a translational model of systemic inflammation that has contributed significantly to our current understanding of sickness behavior and inflammation-associated depression. Previous studies using this model revealed a strong association between cytokine levels, endocrine changes, and psychological sickness symptoms during the acute phase of inflammation. The objective of this randomized, double-blind, placebo-controlled crossover study was to gain insight into potential post-acute physiological and psychological consequences of endotoxin administration that may either persist or newly emerge between 24 and 72 h after injection. The main focus was on associations between serum levels of C-reactive protein (CRP) and affective symptoms as well as alterations in diurnal cortisol profile, the two key features of inflammation-associated depression.

METHODS

Healthy male volunteers (N = 18) received an injection of either endotoxin (0.8 ng/kg) or placebo on two separate but otherwise identical study days, 7 days apart. Blood and saliva samples were collected during acute and post-acute phases after injection to measure blood inflammatory markers (interleukin [IL]-6, IL-1 receptor antagonist [ra], CRP) and salivary cortisol levels. In addition, participants completed a comprehensive battery of questionnaires to assess physical and psychological sickness symptoms.

RESULTS

Endotoxin treatment induced a short-time rise in plasma IL-6 and a longer increase in IL-1ra. The increase in serum CRP was delayed compared to cytokines, peaking at 24 h and gradually decreasing until 72 h after injection. The inflammatory response was accompanied by bodily and psychological sickness symptoms which occurred only in the acute phase, whereas none of the symptoms persisted or recurred in the post-acute phase. Salivary cortisol levels were significantly increased during the acute phase and exhibited pronounced circadian changes. However, no significant differences in diurnal cortisol profiles were observed between placebo and endotoxin conditions on the days after treatment.

CONCLUSION

Our findings suggest that CRP, which is elevated in patients with inflammation-associated depression, does not appear to be responsible for depressive symptomatology. Moreover, a single inflammatory episode is not sufficient to alter diurnal cortisol profiles, as observed in inflammation-associated depression. In addition, the absence of persistent lipopolysaccharide-induced psychological and physiological changes beyond the acute phase further supports the safety of endotoxin administration in humans.

Anxiolytic-like effects of hochuekkito in lipopolysaccharide-treated mice involve interleukin-6 inhibition

Hochuekkito (HET) is a Kampo medicine used to treat postoperative and post-illness general malaise and decreased motivation. HET is known to regulate immunity and modulate inflammation. However, the precise mechanism and effects of HET on inflammation-induced central nervous system disorders remain unclear. This study aimed to assess the effect of HET on inflammation-induced anxiety-like behavior and the mechanism underlying anxiety-like behavior induced by lipopolysaccharide (LPS). Institute of Cancer Research mice were treated with LPS (300 μg/kg, intraperitoneally), a bacterial endotoxin, to induce systemic inflammation. The mice were administered HET (1.0 g/kg, orally) once a day for 2 weeks before LPS treatment. The light-dark box test and the hole-board test were performed 24 h after the LPS injection to evaluate the effects of HET on anxiety-like behaviors. Serum samples were obtained at 2, 5, and 24 h after LPS injection, and interleukin-6 (IL-6) levels in serum were measured. Human and mouse macrophage cells (THP-1 and RAW264.7 cells, respectively) were used to investigate the effect of HET on LPS-induced IL-6 secretion. The repeated administration of HET prevented anxiety-like behavior and decreased serum IL-6 levels in LPS-treated mice. HET significantly suppressed LPS-induced IL-6 secretion in RAW264.7 and THP-1 cells. Similarly, glycyrrhizin, one of the chemical constituents of HET, suppressed LPS-induced anxiety-like behaviors. Our study revealed that HET ameliorated LPS-induced anxiety-like behavior and inhibited IL-6 release in vivo and in vitro. Therefore, we postulate that HET may be useful against inflammation-induced anxiety-like behavior.

Immunopsychiatry – Innovative Technology to Characterize Disease Activity in Autoantibody-Associated Psychiatric Diseases

Background

Anti-neural autoantibody-associated psychiatric disease is a novel field in immunopsychiatry that has been attracting attention thanks to its potentially positive therapeutic outcome and distinct prognosis compared with non-organic psychiatric disease. This review aims to describe recent novel technological developments for improving diagnostics in the field of autoantibody-related psychiatric disease.

Methods

We screened for relevant articles in PubMed for this narrative article. We focused on research methods such as neuroimaging, immune cells and inflammation markers, and molecular biomarkers in human biofluids like serum and cerebrospinal fluid and plasma proteomics.

Results

We introduce several novel methods for investigating autoinflammation with the aim of optimizing therapies for autoantibody-associated psychiatric disease. We describe measuring the translocator protein 18kDa in activated microglia via positron emission tomography imaging, brain volumetric assessment, flow cell cytometry of cerebrospinal fluid and blood, and blood biological probes as well as psychopathological cues to help us gain insights into diagnosing inflammation and brain damage better in psychiatric patients presenting a suspected autoimmune etiology.

Conclusion

Our short methodological review provides an overview of recent developments in the field of autoantibody-related immunopsychiatry. More research is needed to prove their usefulness in diagnosing and treating autoantibody-associated psychiatric disease and its subtypes.

Back to the future of psychoneuroimmunology: Studying inflammation-induced sickness behavior

What do we know about sickness behavior? In this article, I guide you through some of the complexity of sickness behavior occurring after an immune challenge. I highlight the many features of behavioral and affective changes induced during experimental endotoxemia in humans, and describe how little we know about many of these features. I argue that we need to dismantle the components of inflammation-induced sickness behavior, and study each component in detail. I also point out the large inter-individual differences in inflammation-induced behavioral and affective changes, and the fact that psychosocial factors likely interact with inflammation to shape inflammation-induced sickness behavior. PNI clearly lacks investigations of the vulnerability and resilient factors underlying the inter-individual variability in sickness behavior. Throughout the article, I base my argument on my published articles, and provide concrete examples from my experience and the data that I have collected over the past 10 years. Given the relevance of inflammation-induced sickness behavior for inflammation-associated depression and for how people react to infections, I encourage current and future psychoneuroimmunologists to return towards basic science of sickness behavior.

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Inflammation-related sickness behavior is relevant for inflammation-associated depression

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The many features of sickness behavior should be investigated in detail

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There are large inter-individual variability in sickness behavior

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Vulnerability and resilient factors predicting sickness responses are little known

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I call for a return towards basic science of sickness behavior.