Timing and specificity of the cognitive changes induced by interleukin-2 and interferon-alpha treatments in cancer patients

Sustained type I interferon signaling after human immunodeficiency virus type 1 infection of human iPSC derived microglia and cerebral organoids

Human immunodeficiency virus type-1 (HIV-1)-associated neurocognitive disorder (HAND) affects up to half of people living with HIV-1 and causes long term neurological consequences. The pathophysiology of HIV-1-induced glial and neuronal functional deficits in humans remains enigmatic. To bridge this gap, we established a model simulating HIV-1 infection in the central nervous system using human induced pluripotent stem cell (iPSC)-derived microglia combined with sliced neocortical organoids. Incubation of microglia with two replication-competent macrophage-tropic HIV-1 strains (JRFL and YU2) elicited productive infection and inflammatory activation. RNA sequencing revealed significant and sustained activation of type I interferon signaling pathways. Incorporating microglia into sliced neocortical organoids extended the effects of aberrant type I interferon signaling in a human neural context. Collectively, our results illuminate a role for persistent type I interferon signaling in HIV-1-infected microglia in a human neural model, suggesting its potential significance in the pathogenesis of HAND.

Effects of mammary cancer and chemotherapy on neuroimmunological markers and memory function in a preclinical mouse model

Treatment modalities for breast cancer, including cyclophosphamide chemotherapy, have been associated with the development of cognitive decline (CRCD), which is characterized by impairments in memory, concentration, attention, and executive functions. We and others have identified a link between inflammation and decreased cognitive performance in patients with breast cancer receiving chemotherapy. In order to better understand the inflammation-associated molecular changes within the brain related to tumor alone or in combination with chemotherapy, we orthotopically implanted mouse mammary tumors (E0771) into female C57BL/6 mice and administered clinically relevant doses of cyclophosphamide and doxorubicin intravenously at weekly intervals for four weeks. We measured serum cytokines and markers of neuroinflammation at 48 h and up to one month post-treatment and tested memory using a reward-based delayed spatial alternation paradigm. We found that breast tumors and chemotherapy altered systemic inflammation and neuroinflammation. We further found that the presence of tumor and chemotherapy led to a decline in memory over time at the longest delay, when memory was the most taxed, compared to shorter delay times. These findings in a clinically relevant mouse model shed light on possible biomarkers for CRCD and add to the growing evidence that anti-inflammatory strategies have the potential to mitigate cancer- or treatment-related side effects.

Dysregulated neuroimmune interactions and sustained type I interferon signaling after human immunodeficiency virus type 1 infection of human iPSC derived microglia and cerebral organoids

Human immunodeficiency virus type-1 (HIV-1) associated neurocognitive disorder (HAND) affects up to half of HIV-1 positive patients with long term neurological consequences, including dementia. There are no effective therapeutics for HAND because the pathophysiology of HIV-1 induced glial and neuronal functional deficits in humans remains enigmatic. To bridge this knowledge gap, we established a model simulating HIV-1 infection in the central nervous system using human induced pluripotent stem cell (iPSC) derived microglia combined with sliced neocortical organoids. Upon incubation with two replication-competent macrophage-tropic HIV-1 strains (JRFL and YU2), we observed that microglia not only became productively infected but also exhibited inflammatory activation. RNA sequencing revealed a significant and sustained activation of type I interferon signaling pathways. Incorporating microglia into sliced neocortical organoids extended the effects of aberrant type I interferon signaling in a human neural context. Collectively, our results illuminate the role of persistent type I interferon signaling in HIV-1 infected microglial in a human neural model, suggesting its potential significance in the pathogenesis of HAND.

Obesity and psychological distress

The relationship between high body weight and mental health has been studied for several decades. Improvements in the quality of epidemiological, mechanistic and psychological research have brought greater consistency to our understanding of the links. Large-scale population-based epidemiological research has established that high body weight is associated with poorer mental health, particularly depression and subclinical depressive symptoms. There is some evidence for bidirectional relationships, but the most convincing findings are that greater body weight leads to psychological distress rather than the reverse. Particular symptoms of depression and distress may be specifically related to greater body weight. The psychological stress induced by weight stigma and discrimination contributes to psychological distress, and may in turn handicap efforts at weight control. Heightened systemic inflammation and dysregulation of the hypothalamic-pituitary-adrenal axis are biological mechanisms that mediate in part the relationship of greater body weight with poorer mental health. Changing negative societal attitudes to high body weights would improve the wellbeing of people living with obesity, and promote more effective weight-inclusive attitudes and behaviours in society at large, particularly in healthcare settings. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.

Relationships among Inflammatory Biomarkers and Self-Reported Treatment-Related Symptoms in Patients Treated with Chemotherapy for Gynecologic Cancer: A Controlled Comparison

Previous research suggests that inflammation triggers cancer-treatment-related symptoms (i.e., fatigue, depression, and disruptions in sleep and physical activity), but evidence is mixed. This study examined relationships between inflammatory biomarkers and symptoms in patients with gynecologic cancer compared to age-matched women with no cancer history (i.e., controls). Patients (n = 121) completed assessments before chemotherapy cycles 1, 3, and 6, and 6 and 12 months later. Controls (n = 105) completed assessments at similar timepoints. Changes in inflammation and symptomatology were evaluated using random-effects mixed models, and cross-sectional differences between patients and controls in inflammatory biomarkers and symptoms were evaluated using least squares means. Associations among inflammatory biomarkers and symptoms were evaluated using random-effects fluctuation mixed models. The results indicated that compared to controls, patients typically have higher inflammatory biomarkers (i.e., TNF-alpha, TNFR1, TNFR2, CRP, IL-1ra) and worse fatigue, depression, and sleep (ps < 0.05). Patients reported lower levels of baseline physical activity (p = 0.02) that became more similar to controls over time. Significant associations were observed between CRP, depression, and physical activity (ps < 0.05), but not between inflammation and other symptoms. The results suggest that inflammation may not play a significant role in fatigue or sleep disturbance among gynecologic cancer patients but may contribute to depression and physical inactivity.

An exposome connectivity paradigm for the mechanistic assessment of the effects of prenatal and early life exposure to metals on neurodevelopment

The exposome paradigm through an integrated approach to investigating the impact of perinatal exposure to metals on child neurodevelopment in two cohorts carried out in Slovenia (PHIME cohort) and Greece (HERACLES cohort) respectively, is presented herein. Heavy metals are well-known neurotoxicants with well-established links to impaired neurodevelopment. The links between in utero and early-life exposure to metals, metabolic pathway dysregulation, and neurodevelopmental disorders were drawn through urinary and plasma untargeted metabolomics analysis, followed by the combined application of in silico and biostatistical methods. Heavy metal prenatal and postnatal exposure was evaluated, including parameters indirectly related to exposure and health adversities, such as sociodemographic and anthropometric parameters and dietary factors. The primary outcome of the study was that the identified perturbations related to the TCA cycle are mainly associated with impaired mitochondrial respiration, which is detrimental to cellular homeostasis and functionality; this is further potentiated by the capacity of heavy metals to induce oxidative stress. Insufficient production of energy from the mitochondria during the perinatal period is associated with developmental disorders in children. The HERACLES cohort included more detailed data regarding diet and sociodemographic status of the studied population, allowing the identification of a broader spectrum of effect modifiers, such as the beneficial role of a diet rich in antioxidants such as lycopene and ω-3 fatty acids, the negative effect the consumption of food items such as pork and chicken meat has or the multiple impacts of fish consumption. Beyond diet, several other factors have been proven influential for child neurodevelopment, such as the proximity to pollution sources (e.g., waste treatment site) and the broader living environment, including socioeconomic and demographic characteristics. Overall, our results demonstrate the utility of exposome-wide association studies (EWAS) toward understanding the relationships among the multiple factors that determine human exposure and the underlying biology, reflected as omics markers of effect on neurodevelopment during childhood.

[Immune mechanisms of complicity of somatic pathology in the pathogenesis of mental disorders]

Understanding the mechanisms of the relationship between the nervous and immune systems within the framework of the concept of the key role of inflammation, taking into account the involved genetic factors in the development of a wide range of combined forms of somatic and mental diseases, is of interest for research as well as for the development of new approaches to early diagnosis and more effective treatment of these diseases. This review analyzes the immune mechanisms of the development of mental disorders in patients with somatic diseases, in particular, the transmission of an inflammatory signal from the periphery to the CNS and the implementation of the influence of inflammatory factors on neurochemical systems that determine the characteristics of mental functioning. Particular attention is paid to the processes underlying the disruption of the blood-brain barrier caused by peripheral inflammation. Modulation of neurotransmission, changes in neuroplasticity, changes in regional activity of the brain in areas associated with the functions of threat recognition, cognitive processes and memory function, the effect of cytokines on the hypothalamic-pituitary-adrenal system are considered as mechanisms of action of inflammatory factors in the brain. The need to take into account variations in the genes of pro-inflammatory cytokines, which may be the cause of increased genetic vulnerability associated with the risk mental disorders in patients suffering from a certain somatic disease, is emphasized.

Anti-Inflammatory Effect of Traditional Chinese Medicine on the Concept of Mind-Body Interface

In this chapter, we conducted a systemic literature review for the anti-inflammatory effects of Traditional Chinese Medicine (TCM) applying molecular mechanisms focusing on the neuroinflammation and gut-brain axis in three neuropsychiatric disorders: major depressive disorder, Alzheimer's disease, and Parkinson's disease. We demonstrated the anti-inflammation or immunomodulation effects of TCM, including acupuncture, from basic and clinical research, including cellular and molecular approaches. In conclusion, inflammation plays a critical role in the neuropsychopathological process. At the same time, anti-inflammation seems to be the common biological pathway for the effects of TCM and acupuncture in depression, Alzheimer's disease, and Parkinson's disease.

Neurological Complications of Conventional and Novel Anticancer Treatments

Various neurological complications, affecting both the central and peripheral nervous system, can frequently be experienced by cancer survivors after exposure to conventional chemotherapy, but also to modern immunotherapy. In this review, we provide an overview of the most well-known adverse events related to chemotherapy, with a focus on chemotherapy induced peripheral neurotoxicity, but we also address some emerging novel clinical entities related to cancer treatment, including chemotherapy-related cognitive impairment and immune-mediated adverse events. Unfortunately, efficacious curative or preventive treatment for all these neurological complications is still lacking. We provide a description of the possible mechanisms involved to drive future drug discovery in this field, both for symptomatic treatment and neuroprotection.

Chemobrain, Olfactory and Lifestyle Assessment in Onco-Geriatrics: Sex-Mediated Differences between Chemotherapy and Immunotherapy

A possible link between chemotherapy and cognitive impairment has been identified. In the literature, this condition is usually called chemobrain and can mostly affect some memory domain but can lead also to other cognitive impairments. Olfaction, which is known to be linked with cognitive domain and the nociception system, can also be affected by chemotherapy. The aim of this study was to investigate the main cognitive and olfactory abilities and the functional and nutritional state of a cohort of chemotherapy and immunotherapy onco-geriatric patients and control geriatrics subjects. Cognitive, olfactory, geriatric and nutritional assessments were performed through the Mini Mental State Examination (MMSE), Sniffin' Sticks Screening 12, G8 test and a questionnaire on the adherence of the Mediterranean diet, respectively. Our findings show a gender effect on the MMSE. Overall results indicate more pronounced impairments both at the cognitive and frailty level regardless of the type of therapy. On the other hand, the Sniffin' Sticks performances highlight a significant decrease in olfactory perception ability of subjects following immunotherapy. Significant correlations between olfactory performance and MMSE and G8 scores were also found, as well as between MMSE and G8 measures.

Are sick people really more impulsive?: Investigating inflammation-driven impulsivity

In both animals and humans, inflammatory stimuli - especially infections and endotoxin injections - cause "sickness behaviors," including lethargy, malaise, and low mood. An emerging line of research asserts that inflammation may provoke present-focused decision making and impulsivity. The current article assesses that claim in the context of the broader literature - including preclinical models and clinical interventions. This literature presents three challenges to purported inflammation-impulsivity link that have not been addressed to date: (1) the nebulous and imprecise definition of impulsivity; (2) reverse causality; and (3) a lack of causal evidence. These challenges point to ways in which future research designs can improve upon the extant literature to further explore the ostensible relationship between inflammation and impulsivity.

Prenatal and Childhood Immuno-Metabolic Risk Factors for Adult Depression and Psychosis

Depression and psychosis have a developmental component to their origin. Epidemiologic evidence, which we synthesize in this nonsystematic review, suggests that early-life infection, inflammation, and metabolic alterations could play a role in the etiology of these psychiatric disorders. The risk of depression and psychosis is associated with prenatal maternal and childhood infections, which could be mediated by impaired neurodevelopment. Evidence suggests linear dose-response associations between elevated concentrations of circulating inflammatory markers in childhood, particularly the inflammatory cytokine interleukin 6, and the risk for depression and psychosis subsequently in early adulthood. Childhood inflammatory markers are also associated with persistence of depressive symptoms subsequently in adolescence and early adulthood. Developmental trajectories reflecting persistently high insulin levels during childhood and adolescence are associated with a higher risk of psychosis in adulthood, whereas increased adiposity during and after puberty is associated with the risk of depression. Together, these findings suggest that higher levels of infection, inflammation, and metabolic alterations commonly seen in people with depression and psychosis could be a cause for, rather than simply a consequence of, these disorders. Therefore, early-life immuno-metabolic alterations, as well as factors influencing these alterations such as adversity or maltreatment, could represent targets for prevention of these psychiatric disorders. Inflammation could also be an important treatment target for depression and psychosis. The field requires further research to examine sensitive periods when exposure to such immuno-metabolic alterations is most harmful. Interventional studies are also needed to test the potential usefulness of targeting early-life immuno-metabolic alterations for preventing adult depression and psychosis.

Integrating the monoamine and cytokine hypotheses of depression: Is histamine the missing link?

Psychiatric diseases, like depression, largely affect the central nervous system (CNS). While the underlying neuropathology of depressive illness remains to be elucidated, several hypotheses have been proposed as molecular underpinnings for major depressive disorder, including the monoamine hypothesis and the cytokine hypothesis. The monoamine hypothesis has been largely supported by the pharmaceuticals that target monoamine neurotransmitters as a treatment for depression. However, these antidepressants have come under scrutiny due to their limited clinical efficacy, side effects, and delayed onset of action. The more recent, cytokine hypothesis of depression is supported by the ability of immune-active agents to induce "sickness behaviour" akin to that seen with depression. However, treatments that more selectively target inflammation have yielded inconsistent antidepressive results. As such, neither of these hypotheses can fully explain depressive illness pathology, implying that the underlying neuropathological mechanisms may encompass aspects of both theories. The goal of the current review is to integrate these two well-studied hypotheses and to propose a role for histamine as a potential unifying factor that links monoamines to cytokines. Additionally, we will focus on stress-induced depression, to provide an updated perspective of depressive illness research and thereby identify new potential targets for the treatment of major depressive disorder.

Chemokines gene expression in the prefrontal cortex of depressed suicide victims and normal control subjects

Abnormalities of neuroinflammation have been implicated in the pathogenesis of depression and suicide. This is primarily based on the observation that cytokines, which are major inflammatory molecules and play an important role in depression and suicide, are increased in both serum and in postmortem brain of depressed and suicidal subjects. Another class of immune mediators are chemokines which are primarily involved in chemotactic properties and trafficking of immune cells in the central nervous system (CNS). Chemokines also play an important role in CNS function. Whereas chemokines have been studied in the serum of depressed and suicidal patients, their role in brain of depressed or suicidal subjects is relatively unexplored. We studied the gene expression of several chemokines in the prefrontal cortex (PFC) obtained from depressed suicidal (DS) and normal control (NC) subjects. We determined the mRNA expression of several chemokines belonging to CXCL and CCL groups of chemokines using qPCR array technique and qPCR gene expression validation in 24 DS and 24 NC subjects. The postmortem brain samples were obtained from the Maryland Brain Collection. We found that the mRNA expression of chemokines CXCL1, CXCL2, CXCL3 and CCL2 was significantly decreased in the PFC of DS compared with NC subjects. No significant change was observed in CXCL5, CXCL6, CXCL10, CCL8 and CCL19 between DS and NC subjects. Since many of the chemokines are involved in mediating certain important CNS functions, such as neurotrophic effect, neurogenesis, anti-apoptotic growth factor release, modulation of synaptic transmission, brain development and neuronal loss, decreased levels of chemokines can reduce these functions which may be involved in the pathophysiology of depression.

Systemic inflammation and symptomatology in patients with prostate cancer treated with androgen deprivation therapy: Preliminary findings

BACKGROUND

Increases in fatigue, depressive symptomatology, and cognitive impairment are common after the initiation of androgen deprivation therapy (ADT) for prostate cancer. To date, no studies have examined the potential role of inflammation in the development of these symptoms in ADT recipients. The goal of the current study was to examine circulating markers of inflammation as potential mediators of change in fatigue, depressive symptomatology, and cognitive impairment related to the receipt of ADT.

METHODS

Patients treated with ADT for prostate cancer (ADT+; n = 47) were assessed around the time of the initiation of ADT and 6 and 12 months later. An age- and education-matched group of men without a history of cancer (CA-; n = 82) was assessed at comparable time points. Fatigue, depressive symptomatology, and cognitive impairment were assessed with the Fatigue Symptom Inventory, the Center for Epidemiological Studies Depression Scale, and a battery of neuropsychological tests, respectively. Circulating markers of inflammation included interleukin 1 receptor antagonist (IL-1RA), interleukin 6 (IL-6), soluble tumor necrosis factor receptor II (sTNF-RII), and C-reactive protein (CRP).

RESULTS

Fatigue, depressive symptomatology, and serum IL-6 increased significantly over time in the ADT+ group versus the CA- group; rates of cognitive impairment also changed significantly between the groups. No significant changes in IL-1RA, sTNF-RII, or CRP over time were detected. Treatment-related increases in IL-6 were associated with worsening fatigue but not depressive symptomatology or cognitive impairment.

CONCLUSIONS

Results of this preliminary study suggest that increases in circulating IL-6, perhaps due to testosterone inhibition, may play a role in fatigue secondary to receipt of ADT. Additional research is needed to determine whether interventions to reduce circulating inflammation improve fatigue in this population.

Inflammation and the dimensions of depression: A review

Patients with depressive disorders show a wide range of clinical manifestations including cognitive and neurovegetative symptoms. Importantly, these symptoms can differ in terms of biological etiology, and deconstructing depression into specific symptoms may provide valuable insight into the underlying neurobiology. Little research has examined inflammation in the context of depressive dimensions. Here we conduct a narrative review of the existing literature (21 studies) to elucidate whether the depression-inflammation link is symptom specific. Overall, there is evidence that an association exists between neurovegetative symptoms of depression and inflammation, independent of cognitive symptoms. The same cannot be said of cognitive symptoms and inflammation. There is also some evidence of gender differences in the directionality of the relationship between depression and inflammation. Potential explanations for these findings, limitations of the existing literature and recommendations for future research design are discussed.

Late Brain Involvement after Neonatal Immune Activation

The neonatal immune system is still immature, which makes it more susceptible to the infectious agents. Neonatal immune activation is associated with increased permeability of the blood-brain barrier, causing an inflammatory cascade in the CNS and altering behavioral and neurochemical parameters. One of the hypotheses that has been studied is that neuroinflammation may be involved in neurodegenerative processes, such as Alzheimer's disease (AD). We evaluate visuospatial memory, cytokines levels, and the expression of tau and GSK-3β proteins in hippocampus and cortex of animals exposed to neonatal endotoxemia. C57BL/6 mice aging two days received a single injection of subcutaneous lipopolysaccharide (LPS). At 60,120, and 180 days of age, visual-spatial memory was evaluated and the hippocampus and cortex were dissected to evaluate the cytokines levels and expression of tau and GSK-3β proteins. The animals exposed to LPS in the neonatal period present with visuospatial memory impairment at 120 and 180 days of age. Here there was an increase of TNF-α and IL-1β levels in the hippocampus and cortex only at 60 days of age. Here there was an increase in the expression of GSK-3β in hippocampus of the animals at 60, 120, and 180 days of age. In the cortex, this increase occurred in the 120 and 180 days of age. Tau protein expression was high in hippocampus and cortex at 120 days of age and in hippocampus at 180 days of age. The data observed show that neonatal immune activation may be associated with visuospatial memory impairment, neuroinflammation, and increased expression of GSK-3β and Tau proteins in the long term.

Immunological Aspects of Depressive Disorder – The Review

Depression represents a mood disorder and is considered to be one of the most common mental disorders in general. World Health Organization estimates that depression will be the leading cause of disability-adjusted life years, until 2030. Depression is a complex heterogeneous disorder where immune system and its regulation play an important role. Innate and adaptive immunity mecha nisms are included, along with processes of immune activation and suppression. The expression of humoral factors of innate immunity, especially pro-inflammatory cytokines, is increased, whereas the intensity of cellular immune mechanisms, primarily T cells and NK cells, are impaired. The influence of pro-inflammatory cytokines on depression is reflected in their effect on certain enzymes and ensuing reduction of neurotransmitters serotonin and dopamine. They also affect the neuroendocrine function in central nervous system, resulting in increase of cortisol levels and inactivation of glucocorticoid receptors in the periphery, which leads to neurodegeneration and decrease in neurotransmitter production. Certain cytokines affect neuroplasticity through the decreasing of concentration of neurotrophic brain factor and induction of brain cell apoptosis. The results are often contradictory talking about mechanisms of adaptive immunity. On one hand, an increased activity of Tlymphocytes is observed, while on the other, there are evidence of spontaneous apoptosis and impaired function of these cells in depression. In addition, neuroprotective role of autoreactive and regulatory T cells in prevention of depression has also been demonstrated. The aim of this paper is to analyze the current knowledge on the role of immune mechanisms in the pathogenesis of depression.

The role of inflammation in core features of depression: Insights from paradigms using exogenously-induced inflammation

A wealth of evidence has implicated inflammation in the development of depression. Yet, the heterogeneous nature of depression has impeded efforts to understand, prevent, and treat the disease. The purpose of this integrative review is to summarize the connections between inflammation and established core features of depression that exhibit more homogeneity than the syndrome itself: exaggerated reactivity to negative information, altered reward processing, decreased cognitive control, and somatic syndrome. For each core feature, we first provide a brief overview of its relevance to depression and neurobiological underpinnings, and then review evidence investigating a potential role of inflammation. We focus primarily on findings from experimental paradigms of exogenously-induced inflammation. We conclude that inflammation likely plays a role in exaggerated reactivity to negative information, altered reward reactivity, and somatic symptoms. There is less evidence supporting an effect of inflammation on cognitive control as assessed by standard neuropsychological measures. Finally, we discuss implications for future research and recommendationsfor how to test the role of inflammation in the pathogenesis of heterogeneous psychiatric disorders.

Abnormal protein and mRNA expression of inflammatory cytokines in the prefrontal cortex of depressed individuals who died by suicide

BACKGROUND

Depression and stress are major risk factors for suicidal behaviour, and some studies show abnormalities of proinflammatory cytokines in the serum and cerebrospinal fluid (CSF) of depressed and suicidal patients. However, it is not clear if similar abnormalities of cytokines are present in the brain of suicidal and depressed patients.

METHODS

We therefore determined the mRNA (using realtime polymerase chain reaction) and protein (using enzyme-linked immunosorbent assay and Western Blot) expression levels of interleukin (IL)-1β, IL-6, tumour necrosis factor (TNF)-α, lymphotoxin A, lymphotoxin B, IL-8, IL-10 and IL-13 in the prefrontal cortex (PFC) obtained from 24 depressed individuals who died by suicide and 24 nonpsychiatric controls.

RESULTS

We observed that the mRNA and protein levels of IL-1β, IL-6, TNF-α, and lymphotoxin A were significantly increased, and levels of anti-inflammatory cytokine IL-10, and of IL-1 receptor antagonist (IL-1RA) were significantly decreased in the PFC of depressed individuals who died by suicide compared with controls. There were no significant differences in the protein and mRNA levels of IL-8 and IL-13 in the PFC.

LIMITATIONS

The main limitation of this study is that some of the suicide group had been taking antidepressant medication at the time of death.

CONCLUSION

Our results suggest that alterations of cytokines may be associated with the pathophysiology of depressed suicide and there may be an imbalance between pro- and anti-inflammatory cytokines in people who die by suicide. The causes of these increases in the brain of people who die by suicide, therefore, need to be investigated further.

Interoception and Inflammation in Psychiatric Disorders

Despite a historical focus on neurally mediated interoceptive signaling mechanisms, humoral (and even cellular) signals also play an important role in communicating bodily physiological state to the brain. These signaling pathways can perturb neuronal structure, chemistry, and function, leading to discrete changes in behavior. They are also increasingly implicated in the pathophysiology of psychiatric disorders. The importance of these humoral signaling pathways is perhaps most powerfully illustrated in the context of infection and inflammation. Here we provide an overview of how interaction of immune activation of neural and humoral interoceptive mechanisms mediates discrete changes in brain and behavior and highlight how activation of these pathways at specific points in neural development may predispose to psychiatric disorder. As our mechanistic understanding of these interoceptive pathways continues to emerge, it is revealing novel therapeutic targets, potentially heralding an exciting new era of immunotherapies in psychiatry.

The role of neuroinflammation and neurovascular dysfunction in major depressive disorder

Although depression has generally been explained with monoamine theory, it is far more multifactorial, and therapies that address the disease’s pathway have not been developed. In this context, an understanding of neuroinflammation and neurovascular dysfunction would enable a more comprehensive approach to depression. Inflammation is in a sense a type of allostatic load involving the immune, endocrine, and nervous systems. Neuroinflammation is involved in the pathophysiology of depression by increasing proinflammatory cytokines, activating the hypothalamus–pituitary–adrenal axis, increasing glucocorticoid resistance, and affecting serotonin synthesis and metabolism, neuronal apoptosis and neurogenesis, and neuroplasticity. In future, identifying the subtypes of depression with increased vulnerability to inflammation and testing the effects of inflammatory modulating agents in these patient groups through clinical trials will lead to more concrete conclusions on the matter. The vascular depression hypothesis is supported by evidence for the association between vascular disease and late-onset depression and between ischemic brain lesions and distinctive depressive symptoms. Vascular depression may be the entity most suitable for studies of the mechanisms of depression. Pharmacotherapies used in the prevention and treatment of cerebrovascular disease may help prevent vascular depression. In future, developments in structural and functional imaging, electrophysiology, chronobiology, and genetics will reveal the association between depression and brain lesions. This article aims to give a general review of the existing issues examined in the literature pertaining to depression-related neuroinflammatory and vascular functions, related pathophysiology, applicability to depression treatment, and directions for future research.

Low tumor necrosis factor-α levels predict symptom reduction during electroconvulsive therapy in major depressive disorder

OBJECTIVE

Changes in the tumor necrosis factor-α (TNFα) have been associated with major depressive disorder (MDD). Findings concerning the effects of electroconvulsive therapy (ECT) on the TNFα level have been contradictory. The aim was to examine the immediate and long-term changes in the TNFα level and their associations with symptom reduction in patients with MDD during ECT.

METHOD

The study included 30 patients with MDD. Their TNFα levels were measured at baseline and 2 and 4 hr after the first, fifth and last ECT session. Depressive symptoms were assessed with the Montgomery-Asberg Depression Rating Scale (MADRS).

RESULTS

The TNFα level decreased from baseline to the 2- and 4-hr measurements. There was a correlation between the first ECT session TNFα levels and the relative symptom reduction according to the MADRS score after the ECT series. Both the first (baseline) ECT and 4-hr TNFα levels were lower in responders than in nonresponders.

CONCLUSION

ECT consistently induced a decrease in the TNFα level after each studied session. A low TNFα level at the first ECT appeared to predict a symptom reduction. These findings suggest that TNFα might have a role in the pathogenesis in MDD and in the mechanism of action of ECT.

Abnormal gene and protein expression of inflammatory cytokines in the postmortem brain of schizophrenia patients

Immune function abnormalities have been implicated in the pathophysiology of schizophrenia (SZ). This is primarily based on the observation that the levels of proinflammatory cytokines are significantly increased in the serum of SZ patients compared with normal control (NC) subjects. However, it is not known if similar cytokines abnormalities are also present in the brain of SZ patients. To further examine the involvement of inflammatory cytokines in the brain of SZ patients, we determined the protein and mRNA levels of TNF-α, IL-1β, IL-2, IL-6, IL-8, IL-10, IL-13, LTA and IL-1RA in the prefrontal cortex (PFC, Brodmann area 9) of SZ patients. We found that the protein and mRNA expression levels of the cytokines TNF-α and IL-6 are significantly increased and those of IL-10 are significantly decreased in the PFC of SZ patients. No difference in the protein and mRNA levels of IL-1β, IL-13, and IL-1RA was observed between SZ patients and NC subjects. The protein expression levels of IL-8 were significantly decreased and those of LTA were significantly increased in SZ patients, but no significant difference in the mRNA levels of IL-8 and LTA was observed between SZ patients and NC subjects. The levels of IL-2 were undetectable or very low in the postmortem brain of either SZ or NC subjects. These results suggest abnormalities of specific pro- and anti-inflammatory cytokines in the postmortem brain of SZ patients. These observations may have important implications in understanding the role of inflammatory cytokines in the pathophysiology of SZ.

Nested positive feedback loops in the maintenance of major depression: An integration and extension of previous models

Several theories of Major Depressive Disorder (MDD) have previously been proposed, focusing largely on either a psychological (i.e., cognitive/affective), biological, or neural/computational level of description. These theories appeal to somewhat distinct bodies of work that have each highlighted separate factors as being of considerable potential importance to the maintenance of MDD. Such factors include a range of cognitive/attentional information-processing biases, a range of structural and functional brain abnormalities, and also dysregulation within the autonomic, endocrine, and immune systems. However, to date there have been limited efforts to integrate these complimentary perspectives into a single multi-level framework. Here we review previous work in each of these MDD research domains and illustrate how they can be synthesized into a more comprehensive model of how a depressive episode is maintained. In particular, we emphasize how plausible (but insufficiently studied) interactions between the various MDD-related factors listed above can lead to a series of nested positive feedback loops, which are each capable of maintaining an individual in a depressive episode. We also describe how these different feedback loops could be active to different degrees in different individual cases, potentially accounting for heterogeneity in both depressive symptoms and treatment response. We conclude by discussing how this integrative model might extend understanding of current treatment mechanisms, and also potentially guide the search for markers to inform treatment selection in individual cases.

Inflammation, Self-Regulation, and Health: An Immunologic Model of Self-Regulatory Failure

Self-regulation is a fundamental human process that refers to multiple complex methods by which individuals pursue goals in the face of distractions. Whereas superior self-regulation predicts better academic achievement, relationship quality, financial and career success, and lifespan health, poor self-regulation increases a person's risk for negative outcomes in each of these domains and can ultimately presage early mortality. Given its centrality to understanding the human condition, a large body of research has examined cognitive, emotional, and behavioral aspects of self-regulation. In contrast, relatively little attention has been paid to specific biologic processes that may underlie self-regulation. We address this latter issue in the present review by examining the growing body of research showing that components of the immune system involved in inflammation can alter neural, cognitive, and motivational processes that lead to impaired self-regulation and poor health. Based on these findings, we propose an integrated, multilevel model that describes how inflammation may cause widespread biobehavioral alterations that promote self-regulatory failure. This immunologic model of self-regulatory failure has implications for understanding how biological and behavioral factors interact to influence self-regulation. The model also suggests new ways of reducing disease risk and enhancing human potential by targeting inflammatory processes that affect self-regulation.

Brain Structures Implicated in Inflammation-Associated Depression

Systemic inflammation rapidly impairs mood, motivation, and cognition inducing a stereotyped cluster of symptoms collectively known as "sickness behaviors." When inflammation is severe or chronic, these behavioral changes can appear indistinguishable from major depressive disorder (MDD). Human and rodent neuroimaging combined with experimental inflammatory challenges has clarified the neural circuitry associated with many of the key features of inflammation-induced-sickness behavior, and in so doing revealed often-remarkable commonalities with circuit abnormalities observed in MDD. This review aims to provide the first synthesis of this work illustrating areas of convergence and divergence with the MDD literature as well as highlighting areas for future study.

LW-AFC, a new formula derived from Liuwei Dihuang decoction, ameliorates behavioral and pathological deterioration via modulating the neuroendocrine-immune system in PrP-hAβPPswe/PS1ΔE9 transgenic mice

BACKGROUND

Accumulating evidence implicates the neuroendocrine immunomodulation (NIM) network in the physiopathological mechanism of Alzheimer's disease (AD). Notably, we previously revealed that the NIM network is dysregulated in the PrP-hAβPPswe/PS1ΔE9 (APP/PS1) transgenic mouse model of AD.

METHODS

After treatment with a novel Liuwei Dihuang formula (LW-AFC), mice were cognitively evaluated in behavioral experiments. Neuron loss, amyloid-β (Aβ) deposition, and Aβ level were analyzed using Nissl staining, immunofluorescence, and an AlphaLISA assay, respectively. Multiplex bead analysis, a radioimmunoassay, immunochemiluminometry, and an enzyme-linked immunosorbent assay (ELISA) were used to measure cytokine and hormone levels. Lymphocyte subsets were detected using flow cytometry. Data between two groups were compared using a Student's t test. Comparison of the data from multiple groups against one group was performed using a one-way analysis of variance (ANOVA) followed by a Dunnett's post hoc test or a two-way repeated-measures analysis of variance with a Tukey multiple comparisons test.

RESULTS

LW-AFC ameliorated the cognitive impairment observed in APP/PS1 mice, including the impairment of object recognition memory, spatial learning and memory, and active and passive avoidance. In addition, LW-AFC alleviated the neuron loss in the hippocampus, suppressed Aβ deposition in the brain, and reduced the concentration of Aβ1-42 in the hippocampus and plasma of APP/PS1 mice. LW-AFC treatment also significantly decreased the secretion of corticotropin-releasing hormone and gonadotropin-releasing hormone in the hypothalamus, and adrenocorticotropic hormone, luteinizing hormone, and follicle-stimulating hormone in the pituitary. Moreover, LW-AFC increased CD8+CD28+ T cells, and reduced CD4+CD25+Foxp3+ T cells in the spleen lymphocytes, downregulated interleukin (IL)-1β, IL-2, IL-6, IL-23, granulocyte-macrophage colony stimulating factor, and tumor necrosis factor-α and -β, and upregulated IL-4 and granulocyte colony stimulating factor in the plasma of APP/PS1 mice.

CONCLUSIONS

LW-AFC ameliorated the behavioral and pathological deterioration of APP/PS1 transgenic mice via the restoration of the NIM network to a greater extent than either memantine or donepezil, which supports the use of LW-AFC as a potential agent for AD therapy.

Cytokine-mediated blood brain barrier disruption as a conduit for cancer/chemotherapy-associated neurotoxicity and cognitive dysfunction

Neurotoxicity is a common side effect of chemotherapy treatment, with unclear molecular mechanisms. Clinical studies suggest that the most frequent neurotoxic adverse events affect memory and learning, attention, concentration, processing speeds and executive function. Emerging preclinical research points toward direct cellular toxicity and induction of neuroinflammation as key drivers of neurotoxicity and subsequent cognitive impairment. Emerging data now show detectable levels of some chemotherapeutic agents within the CNS, indicating potential disruption of blood brain barrier integrity or transport mechanisms. Blood brain barrier disruption is a key aspect of many neurocognitive disorders, particularly those characterized by a proinflammatory state. Importantly, many proinflammatory mediators able to modulate the blood brain barrier are generated by tissues and organs that are targets for chemotherapy-associated toxicities. This review therefore aims to explore the hypothesis that peripherally derived inflammatory cytokines disrupt blood brain barrier permeability, thereby increasing direct access of chemotherapeutic agents into the CNS to facilitate neuroinflammation and central neurotoxicity.

Microglia activation is associated with IFN-α induced depressive-like behavior

Inflammatory immune activation has been frequently associated with the development of major depression. This association was confirmed in patients receiving long-term treatment with pro-inflammatory interferon-α (IFN-α). Microglia, the resident immune cells in the brain, might serve as an important interface in this immune system-to-brain communication. The aim of the present study was to investigate the role of microglia in an IFN-α mouse model of immune-mediated depression. Male BALB/c mice were treated with daily injections of IFN-α for two weeks. Depressive-like behavior was analyzed in the forced swim and tail suspension test. Activation of microglia was measured by flow cytometry. Pro-inflammatory M1 type (MHC-II, CD40, CD54, CD80, CD86, CCR7), anti-inflammatory M2 type (CD206, CD200R), and maturation markers (CD11c, CCR7) were tested, as well as the chemokine receptor CCR2. IFN-α led to a significant increase in depressive-like behavior and expression of the pro-inflammatory surface markers MHC-II, CD86, and CD54, indicating M1 polarization. Because IFN-α-treated mice showed great individual variance in the behavioral response to IFN-α, they were further divided into vulnerable and non-vulnerable subgroups. Only IFN-α vulnerable mice (characterized by their development of depressive-like behavior in response to IFN-α) showed an increased expression of MHC-II and CD86, while CD54 was similarly enhanced in both subgroups. Thus, IFN-α-induced activation of microglia was specifically associated with depressive-like behavior.

A clinically relevant dose of cyclophosphamide chemotherapy impairs memory performance on the delayed spatial alternation task that is sustained over time as mice age

BACKGROUND

Cyclophosphamide chemotherapy is a mainstay of adjuvant breast cancer treatment. Unfortunately, this drug is associated with cognitive impairments in cancer patients that may accelerate cognitive aging. Memory is particularly affected in many patients. In order to better understand the precise cognitive impairments caused by this chemotherapy agent, we investigated a clinically relevant dose and administration paradigm on delayed spatial memory abilities in C57BL/6 mice. We utilized a delayed alternation paradigm similar to a delayed match to sample paradigm reported to be sensitive in human neurotoxicology research.

METHODS

A dose of 200mg/kg cyclophosphamide was administered intravenously (at weekly intervals) for 4 weeks to C57BL/6 mice starting at 6 ½ months of age. Memory was tested in mice using a reward-based delayed spatial alternation paradigm with delay values of 1.5, 3, 6.1, 12.4 and 25s presented randomly over 80 sessions (16 reinforcers per session), and testing began at the initiation of chemotherapy through 3 months.

RESULTS

At the longest delay, i.e., that requiring the greatest memory, mice treated with chemotherapy exhibited a significant decline over time in percent correct which leveled off compared to controls that continued to improve slightly.

CONCLUSIONS

Our clinically relevant model shows cyclophosphamide chemotherapy causes a slight decline in delayed spatial memories at the longest delay that is sustained over time as mice age.

The anti-aging effects of LW-AFC via correcting immune dysfunctions in senescence accelerated mouse resistant 1 (SAMR1) strain

Although there were considerable advances in the anti-aging medical field, it is short of therapeutic drug for anti-aging. Mounting evidence indicates that the immunosenescence is the key physiopathological mechanism of aging. This study showed the treatment of LW-AFC, an herbal medicine, decreased the grading score of senescence, increased weight, prolonged average life span and ameliorated spatial memory impairment in 12- and 24-month-old senescence accelerated mouse resistant 1 (SAMR1) strain. And these anti-aging effects of LW-AFC were more excellent than melatonin. The administration of LW-AFC enhanced ConA- and LPS-induced splenocyte proliferation in aged SAMR1 mice. The treatment of LW-AFC not only reversed the decreased the proportions of helper T cells, suppressor T cells and B cells, the increased regulatory T cells in the peripheral blood of old SAMR1 mice, but also could modulate the abnormal secretion of IL-1β, IL-2, IL-6, IL-17, IL-23, GM-CSF, IFN-γ, TNF-α, TNF-β, RANTES, eotaxin, MCP-1, IL-4, IL-5, IL-10 and G-CSF. These data indicated that LW-AFC reversed the immunosenescence status by restoring immunodeficiency and decreasing chronic inflammation and suggested LW-AFC may be an effective anti-aging agent.

Isoflurane in the presence or absence of surgery increases hippocampal cytokines associated with memory deficits and responses to brain injury in rats

Evidence from experimental animal studies convincingly argues for a role of pro-inflammatory cytokines due to surgical trauma in causing postoperative cognitive dysfunction. However, other studies have shown exposure to 2-4h of isoflurane anesthetic without surgical trauma can also impair cognitive function. We aimed to determine cytokine changes over time following isoflurane exposure in the presence and absence of surgery and examine subsequent cognitive function. Male rats were exposed to isoflurane (1.8%, 4h) with or without laparotomy or control conditions and tested in a contextual fear conditioning paradigm 8 days later. On day 9 rats were perfused, serum and hippocampal samples were collected and 24 cytokines were analysed. Groups of rats exposed as above were killed 6 or 48h after isoflurane exposure to examine early cytokine changes. Isoflurane exposure resulted in significantly less freezing in the contextual fear conditioning test (F(2,31)=6.11, P=0.006) and addition of laparotomy caused no further deficits (P>0.05). At 6h post isoflurane exposure an immunosuppressive response was observed in the serum while hippocampal cytokines were largely unchanged. These finding suggest isoflurane alone causes inflammatory changes and cognitive deficits. The addition of a laparotomy had a negligible effect. Early after isoflurane exposure changes in serum and hippocampal cytokines were divergent but by 9 days were aligned. At this time cytokines associated with memory deficits and brain injury processes were significantly elevated in serum and brain.

Inflammation as a mediator of the relationship between cortical thickness and metabolic syndrome

Metabolic Syndrome (MetS), the clustering of obesity, high blood pressure, and disordered glucose and lipid/lipoprotein metabolism within a single individual, is associated with poorer cognitive function. It has been hypothesized that cognitive impairment in MetS occurs primarily within the context of inflammation. MetS risk factors are also associated with thinning of the cerebral cortex. However, the mechanisms by which MetS and inflammation affect the brain are poorly understood. The present study used statistical mediation to examine the relationship between MetS risk factors, cortical thickness in a priori regions of interest (ROIs) and inflammation. ROIs were chosen from the previous literature. Forty-three adults between the ages of 40 and 60 years underwent a health screen, neuropsychological testing and structural magnetic resonance imaging. Serum levels of pro-inflammatory markers (interleukin 1, interleukin 2, interleukin 6 and C-Reactive Protein) were measured using enzyme-linked immunosorbent assays. A higher number of MetS risk factors were associated with thinning in the inferior frontal ROI (β = -0.35, p = 0.019) as well as higher levels of serum interleukin 2 (β = 0.31, p = 0.04). A higher level of serum interleukin 2 was also associated with reduced thickness in the inferior frontal gyrus (β = -0.41, p = 0.013). After accounting for the effects of interleukin 2, the number of MetS risk factors was no longer associated with cortical thickness in the inferior frontal gyrus indicating successful statistical mediation. The results indicate a potentially important role for inflammation in linking MetS to cortical thinning and cognitive vulnerability.

Proinflammatory cytokines and their membrane-bound receptors are altered in the lymphocytes of schizophrenia patients

Abnormalities of protein levels of proinflammatory cytokines and their soluble receptors have been reported in the plasma/serum of schizophrenia (SZ) patients. To examine if SZ is also associated with the abnormal gene expression of cytokines and their membrane-bound receptors, we studied mRNA expression of proinflammatory cytokines and their receptors in lymphocytes of SZ patients and normal control (NC) subjects. We determined the protein and mRNA expression of proinflammatory cytokines and mRNA expression of their receptors in lymphocytes from 30 SZ patients and 30 drug-free NC subjects. The subjects were diagnosed according to DSM-IV criteria. Protein levels of cytokines were determined by ELISA, and mRNA levels in lymphocytes were determined by the qPCR method. We found that the mRNA levels of IL-6, TNF-α, IL-1R1, TNFR1, and TNFR2, but not IL-1β, IL-1R2, IL-1RA, IL-6R, or GP130 were significantly increased in lymphocytes of SZ patients compared with NC subjects. We also found that the protein expression of IL-6 and TNF-α, but not IL-1β, was also significantly increased in SZ patients compared with NC subjects. These studies suggest that in addition to the reported abnormalities of proinflammatory cytokines and their soluble receptors in the plasma of SZ patients, an abnormal gene expression of these cytokines and their membrane-bound receptors may be involved in the pathogenesis of SZ.

Association of inflammatory biomarkers with depressive symptoms and cognitive decline in a community-dwelling healthy older sample: a 3-year follow-up study

BACKGROUND

The relationship between the pathophysiology of dementia and neuroinflammation is well-known. The number of reports stating that depression is a risk factor for dementia has recently been increasing. These epidemiological findings suggest the possibility that both depression and dementia have common pathophysiological backgrounds of neuroinflammation.

METHODS

The sample consists of 64 non-demented community-dwelling older participants aged 65 years or over. Participants were assessed at baseline (2004-2006) and 3 years later (2007-2009). Plasma concentration of markers of inflammation (interleukins (IL)-1β, IL-2, IL-6, soluble interleukin-2 receptor (sIL-2R), soluble interleukin-6 receptor (sIL-6R), high sensitivity C-reactive protein (hsCRP) and tumor necrosis factor (TNF)-α) were measured at baseline. Depression symptoms were assessed with the Beck Depression Inventory (BDI) and cognitive decline was assessed with the Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB) and Clock Drawing Test (CDT) at baseline and follow-up. All analyses were adjusted for age, gender and years of education.

RESULTS

In the cross-sectional analysis, the present study found soluble IL-2 receptor (sIL-2R) to be associated only with the MMSE score at baseline in men. In the longitudinal analysis, none of our inflammatory biomarkers were associated with either depressive symptoms or cognitive decline.

LIMITATIONS

The present study consists of small number of participants and body mass index (BMI) scores were not obtained.

CONCLUSIONS

Our findings suggest that sIL-2R is associated with current cognitive function in men. None of our inflammatory markers predicted future depressive state or cognitive decline in our community-dwelling healthy older sample.

Systemic inflammation and the brain: novel roles of genetic, molecular, and environmental cues as drivers of neurodegeneration

The nervous and immune systems have evolved in parallel from the early bilaterians, in which innate immunity and a central nervous system (CNS) coexisted for the first time, to jawed vertebrates and the appearance of adaptive immunity. The CNS feeds from, and integrates efferent signals in response to, somatic and autonomic sensory information. The CNS receives input also from the periphery about inflammation and infection. Cytokines, chemokines, and damage-associated soluble mediators of systemic inflammation can also gain access to the CNS via blood flow. In response to systemic inflammation, those soluble mediators can access directly through the circumventricular organs, as well as open the blood–brain barrier. The resulting translocation of inflammatory mediators can interfere with neuronal and glial well-being, leading to a break of balance in brain homeostasis. This in turn results in cognitive and behavioral manifestations commonly present during acute infections – including anorexia, malaise, depression, and decreased physical activity – collectively known as the sickness behavior (SB). While SB manifestations are transient and self-limited, under states of persistent systemic inflammatory response the cognitive and behavioral changes can become permanent. For example, cognitive decline is almost universal in sepsis survivors, and a common finding in patients with systemic lupus erythematosus. Here, we review recent genetic evidence suggesting an association between neurodegenerative disorders and persistent immune activation; clinical and experimental evidence indicating previously unidentified immune-mediated pathways of neurodegeneration; and novel immunomodulatory targets and their potential relevance for neurodegenerative disorders.

Chemobrain: a critical review and causal hypothesis of link between cytokines and epigenetic reprogramming associated with chemotherapy

One consequence of modern cancer therapy is chemotherapy related cognitive dysfunction or "chemobrain", the subjective experience of cognitive deficits at any point during or following chemotherapy. Chemobrain, a well-established clinical syndrome, has become an increasing concern because the number of long-term cancer survivors is growing dramatically. There is strong evidence that correlates changes in peripheral cytokines with the development of chemobrain in commonly used chemotherapeutic drugs for different types of cancer. However, the mechanisms by which these cytokines elicit change in the central nervous system are still unclear. In this review, we hypothesize that the administration of chemotherapy agents initiates a cascade of biological changes, with short-lived alterations in the cytokine milieu inducing persistent epigenetic alterations. These epigenetic changes lead to changes in gene expression, alterations in metabolic activity and neuronal transmission that are responsible for generating the subjective experience of cognition. This speculative but testable hypothesis should help to gain a comprehensive understanding of the mechanism underlying cognitive dysfunction in cancer patients. Such knowledge is critical to identify pharmaceutical targets with the potential to prevent and treat cancer-treatment related cognitive dysfunction and similar disorders.

Rapid Regulation of Depression-Associated Genes in a New Mouse Model Mimicking Interferon-α-Related Depression in Hepatitis C Virus Infection

Major depression is a serious side effect of interferon-α (IFN-α), which is used in the therapy of hepatitis C virus (HCV) infection. Due to the lack of reproducible animal models, the mechanisms underlying IFN-α-related depression are largely unknown. We herein established a mouse model, in which murine IFN-α (250 IU/day) and polyinosinic/polycytidylic acid (poly(I:C); 1 μg/day), a toll-like receptor-3 (TLR3) agonist that mimics the effect of HCV double-strand RNA, were continuously infused into the lateral ventricle via miniosmotic pumps over up to 14 days. The delivery of IFN-α and poly(I:C), but not of IFN-α or poly(I:C) alone, resulted in a reproducible depression-like state that was characterized by reduced exploration behavior in open-field tests, increased immobility in tail suspension and forced swimming tests, and a moderate loss of body weight. In the hippocampus and prefrontal cortex, the pro-inflammatory genes TNF-α, IL-6, tissue inhibitor of metalloproteinases-1 (Timp-1), CXC motif ligand-1 (Cxcl1), Cxcl10, and CC motif ligand-5 (Ccl5) were synergistically induced by IFN-α and poly(I:C), most pronounced after 14-day exposure. In comparison, the interferon-inducible genes of signal transducer and activator of transcription-1 (Stat1), guanylate binding protein-1 (Gbp1), proteasome subunit-β type-9 (Psmb9), ubiquitin-conjugating enzyme E2L-6 (Ube2l6), receptor transporter protein-4 (Rtp4), and GTP cyclohydrolase-1 (Gch1), which had previously been elevated in the blood of IFN-α-treated patients developing depression, in the brains of suicidal individuals, and in primary neurons exposed to IFN-α and poly(I:C), were induced even earlier, reaching maximum levels mostly after 24 hours. We propose that interferon-inducible genes might be useful markers of imminent depression.

Common biological pathways underlying the psychoneurological symptom cluster in cancer patients

BACKGROUND

A symptom cluster is a group of symptoms that occur together and are interrelated. The clinical implication of symptom cluster research is to use the clustering patterns of symptoms to understand the mechanisms for these symptoms and develop management strategies targeted at multiple symptoms.

OBJECTIVE

The purposes of this review were to summarize the evidence for a psychoneurological symptom cluster in cancer patients, to provide information regarding the underlying biological mechanisms for each of the psychoneurological symptoms within the cluster, and to propose possible common biological pathways that may underlie this cluster.

METHODS

A systematic review of the literature was conducted.

RESULTS

Empirical evidence exists to support a cluster of psychoneurological symptoms (ie, depressive symptoms, cognitive disturbance, fatigue, sleep disturbance, pain). At a molecular level, common biological pathways (ie, proinflammatory cytokines, hypothalamic-pituitary-adrenal axis, and monoamine neurotransmission system) may underlie the development of symptoms within this cluster. Activation of proinflammatory cytokines is proposed as a first stage of mechanistic pathway. However, other biological factors, such as lowered estrogen or hemoglobin levels, may influence psychoneurological cluster.

CONCLUSION

Additional studies are needed to confirm the roles of cytokines as well as other biological factors in the development of the psychoneurological cluster and to determine the biomarkers to identify the subgroups of cancer patients who are at greatest risk for this cluster.

IMPLICATIONS FOR PRACTICE

This information can be used by researchers and clinicians to guide the selection of symptom management strategies that are ideally targeted to the biological mechanisms that underlie this symptom cluster.

The impact of escitalopram on IL-2-induced neuroendocrine, immune, and behavioral changes in patients with malignant melanoma: preliminary findings

Interleukin (IL)-2, a T-cell cytokine used to treat malignant melanoma, can induce profound depression. To determine whether pretreatment with the antidepressant escitalopram could reduce IL-2-induced neuroendocrine, immune, and neurobehavioral changes, 20 patients with Stage IV melanoma were randomized to either placebo or the serotonin reuptake inhibitor, escitalopram (ESC) 10-20 mg/day, 2 weeks before, and during IL-2 treatment (720 000 units/kg Q8 h × 5 days (1 cycle) every 3 weeks × 4 cycles). Generalized estimation equations were used to examine HPA axis activity (plasma ACTH and cortisol), immune activation (plasma IL-6), and depressive symptoms (Hamilton Depression Rating Scale (HDRS) score). Tolerance of IL-2 treatment (concomitant medications required) and adherence (number of IL-2 doses received) were also assessed. Both the groups (ESC (n=9), placebo (n=11)) exhibited significant IL-2-induced increases in plasma cortisol, IL-6, and depressive symptoms (p<0.05), as well as a temporal trend for increases in plasma ACTH (p=0.054); the effects of age and treatment were not significant. Higher plasma ACTH concentrations were associated with higher depressive symptoms during cycles 1-3 of IL-2 therapy (p<0.01). Although ESC had no significant effects on ACTH, cortisol, IL-6, tolerance of, or adherence to IL-2, ESC treatment was associated with lower depressive symptoms, ie, a maximal difference of ∼3 points on the HDRS, which, though not statistically significant (in part, due to small sample size), represents a clinically significant difference according to the National Institute for Health and Clinical Excellence guidelines. A larger sample size will establish whether antidepressant pretreatment can prevent IL-2-induced neurobehavioral changes.

Inflammatory cytokines in depression: neurobiological mechanisms and therapeutic implications

Mounting evidence indicates that inflammatory cytokines contribute to the development of depression in both medically ill and medically healthy individuals. Cytokines are important for development and normal brain function, and have the ability to influence neurocircuitry and neurotransmitter systems to produce behavioral alterations. Acutely, inflammatory cytokine administration or activation of the innate immune system produces adaptive behavioral responses that promote conservation of energy to combat infection or recovery from injury. However, chronic exposure to elevated inflammatory cytokines and persistent alterations in neurotransmitter systems can lead to neuropsychiatric disorders and depression. Mechanisms of cytokine behavioral effects involve activation of inflammatory signaling pathways in the brain that results in changes in monoamine, glutamate, and neuropeptide systems, and decreases in growth factors, such as brain-derived neurotrophic factor. Furthermore, inflammatory cytokines may serve as mediators of both environmental (e.g. childhood trauma, obesity, stress, and poor sleep) and genetic (functional gene polymorphisms) factors that contribute to depression's development. This review explores the idea that specific gene polymorphisms and neurotransmitter systems can confer protection from or vulnerability to specific symptom dimensions of cytokine-related depression. Additionally, potential therapeutic strategies that target inflammatory cytokine signaling or the consequences of cytokines on neurotransmitter systems in the brain to prevent or reverse cytokine effects on behavior are discussed.

At the extreme end of the psychoneuroimmunological spectrum: delirium as a maladaptive sickness behaviour response

Delirium is a common and severe neuropsychiatric syndrome characterised by acute deterioration and fluctuations in mental status. It is precipitated mainly by acute illness, trauma, surgery, or drugs. Delirium affects around one in eight hospital inpatients and is associated with multiple adverse consequences, including new institutionalisation, worsening of existing dementia, and death. Patients with delirium show attentional and other cognitive deficits, altered alertness (mostly reduced, but some patients develop agitation and hyperactivity), altered sleep-wake cycle and psychoses. The pathways from the various aetiologies to the heterogeneous clinical presentations are hardly studied and are poorly understood. One of the key questions, which research is only now beginning to address, is how the factors determining susceptibility interact with the stimuli that trigger delirium. Inflammatory signals arising during systemic infection evoke sickness behaviour, a coordinated set of adaptive changes initiated by the host to respond to, and to counteract, infection. It is now clear that the same systemic inflammatory signals can have severe deleterious effects on brain function when occuring in old age or in the presence of neurodegenerative disease. Multiple animal studies now show that even mild acute systemic inflammation can induce exaggerated sickness behaviour responses and cognitive dysfunction in aged animals or those with prior degenerative pathology when compared to young and/or healthy controls. These findings appear highly promising in understanding aspects of delirium. In this review our aim is to describe and assess the parallels between exaggerated sickness behaviour in vulnerable animals and delirium in older humans. We discuss inflammatory and stress-related triggers of delirium in the context of new animal models that allow us to dissect some aspects of the mechanisms underpinning these episodes. We discuss some differences between the sickness behaviour syndrome model and delirium in the context of the complexity in the latter due to other factors such as prior pathology, psychological stress and drug effects. We conclude that, with appropriate caveats, the study of sickness behaviour in the vulnerable brain offers a promising route to uncover the mechanisms of this common and serious unmet medical need.

Fatigue and cognitive symptoms in patients with diabetes: relationship with disease phenotype and insulin treatment

Neurobehavioral symptoms are frequently reported in patients with diabetes. Nevertheless, the characterization of the specific symptom dimensions that develop in diabetic patients with respect to disease phenotype and treatment status remains obscure. This study comparatively assessed fatigue symptoms and cognitive performance using a dimensional approach in 21 patients with insulin-treated type 1 diabetes, 24 type 2 diabetic patients either insulin-free or undergoing insulin treatment for at least six months, and 15 healthy subjects. Specific dimensions of fatigue were assessed using the Multidimensional-Fatigue-Inventory (MFI). Cognitive performance on tests of choice reaction time, pattern recognition memory and spatial planning was evaluated using the Cambridge-Neuropsychological-Automated-Battery (CANTAB). Body mass index (BMI) and glycated-hemoglobin (HbA1C) concentrations were collected, as well as information on diabetes complications and disease duration. Patients with type 2 diabetes, regardless of insulin treatment status, exhibited higher scores of fatigue, primarily in the dimensions of general and physical fatigue as well as reduced activity. Cognitive alterations, in the form of longer reaction times and impaired spatial planning, were also detected in type 2 diabetic patients treated with insulin. These alterations were overall unrelated to glucose control, as reflected in HbA1C levels, and were not explained by complications and duration of diabetes. No specific alteration was measured in type 1 diabetic patients who exhibited fatigue scores and cognitive performance comparable to healthy participants. While associated with fatigue, increased BMI did not significantly account for the relationship of type 2 diabetes with general fatigue and physical fatigue. BMI, however, modulated the association of type 2 diabetes with reduced activity and the association of insulin-treated type 2 diabetes with psychomotor slowing. These findings reveal specific fatigue and cognitive symptoms in patients with type 2 diabetes and suggest the involvement of differential pathophysiological processes.