Infection-induced proinflammatory cytokines are associated with decreases in positive affect, but not increases in negative affect

Stress to inflammation and anhedonia: Mechanistic insights from preclinical and clinical models

Anhedonia, as evidenced by impaired pleasurable response to reward, reduced reward motivation, and/or deficits in reward-related learning, is a common feature of depression. Such deficits in reward processing are also an important clinical target as a risk factor for depression onset. Unfortunately, reward-related deficits remain difficult to treat. To address this gap and inform the development of effective prevention and treatment strategies, it is critical to understand the mechanisms that drive impairments in reward function. Stress-induced inflammation is a plausible mechanism of reward deficits. The purpose of this paper is to review evidence for two components of this psychobiological pathway: 1) the effects of stress on reward function; and 2) the effects of inflammation on reward function. Within these two areas, we draw upon preclinical and clinical models, distinguish between acute and chronic effects of stress and inflammation, and address specific domains of reward dysregulation. By addressing these contextual factors, the review reveals a nuanced literature which might be targeted for additional scientific inquiry to inform the development of precise interventions.

Sleep and Healthy Aging Research on Depression (SHARE-D) randomized controlled trial: Protocol overview of an experimental model of depression with insomnia, inflammation, and affect mechanisms in older adults

Depression, one of the most common diseases in older adults, carries significant risk for morbidity and mortality. Because of the burgeoning population of older adults, the enormous burden of late-life depression, and the limited efficacy of current antidepressants in older adults, biologically plausible models that translate into selective depression prevention strategies are needed. Insomnia predicts depression recurrence and is a modifiable target to prevent incident and recurrent depression in older adults. Yet, it is not known how insomnia gets converted into biological- and affective risk for depression, which is critical for identification of molecular targets for pharmacologic interventions, and for refinement of insomnia treatments that target affective responding to improve efficacy. Sleep disturbance activates inflammatory signaling and primes immune responses to subsequent inflammatory challenge. In turn, inflammatory challenge induces depressive symptoms, which correlate with activation of brain regions implicated in depression. This study hypothesizes that insomnia serves as a vulnerability factor for inflammation-related depression; older adults with insomnia will show heightened inflammatory- and affective responding to inflammatory challenge as compared to those without insomnia. To test this hypothesis, this protocol paper describes a placebo-controlled, randomized, double-blind study of low dose endotoxin in older adults (n = 160; 60-80 y) with insomnia vs. comparison controls without insomnia. The aims of this study are to examine differences in depressive symptoms, measures of negative affective responding, and measures of positive affective responding as a function of insomnia and inflammatory challenge. If the hypotheses are confirmed, older adults with two "hits", insomnia and inflammatory activation, would represent a high risk group to be prioritized for monitoring and for depression prevention efforts using treatments that target insomnia or inflammation. Moreover, this study will inform the development of mechanism-based treatments that target affect responses in addition to sleep behaviors, and which might also be coupled with efforts to reduce inflammation to optimize efficacy of depression prevention.

Is depression the missing link between inflammatory mediators and cancer?

Patients with cancer are at greater risk of developing depression in comparison to the general population and this is associated with serious adverse effects, such as poorer quality of life, worse prognosis and higher mortality. Although the relationship between depression and cancer is now well established, a common underlying pathophysiological mechanism between the two conditions is yet to be elucidated. Existing theories of depression, based on monoamine neurotransmitter system dysfunction, are insufficient as explanations of the disorder. Recent advances have implicated neuroinflammatory mechanisms in the etiology of depression and it has been demonstrated that inflammation at a peripheral level may be mirrored centrally in astrocytes and microglia serving to promote chronic levels of inflammation in the brain. Three major routes to depression in cancer in which proinflammatory mediators are implicated, seem likely. Activation of the kynurenine pathway involving cytokines, increases tryptophan catabolism, resulting in diminished levels of serotonin which is widely acknowledged as being the hallmark of depression. It also results in neurotoxic effects on brain regions thought to be involved in the evolution of major depression. Proinflammatory mediators also play a crucial role in impairing regulatory glucocorticoid mediated feedback of the hypothalamic-pituitary-adrenal axis, which is activated by stress and considered to be involved in both depression and cancer. The third route is via the glutamatergic pathway, whereby glutamate excitotoxicity may lead to depression associated with cancer. A better understanding of the mechanisms underlying these dysregulated and other newly emerging pathways may provide a rationale for therapeutic targeting, serving to improve the care of cancer patients.

Serum Cytokines Predict Neurological Damage in Genetically Diverse Mouse Models

Viral infections contribute to neurological and immunological dysfunction driven by complex genetic networks. Theiler's murine encephalomyelitis virus (TMEV) causes neurological dysfunction in mice and can model human outcomes to viral infections. Here, we used genetically distinct mice from five Collaborative Cross mouse strains and C57BL/6J to demonstrate how TMEV-induced immune responses in serum may predict neurological outcomes in acute infection. To test the hypothesis that serum cytokine levels can provide biomarkers for phenotypic outcomes of acute disease, we compared cytokine levels at pre-injection, 4 days post-injection (d.p.i.), and 14 d.p.i. Each strain produced unique baseline cytokine levels and had distinct immune responses to the injection procedure itself. Thus, we eliminated the baseline responses to the injection procedure itself and identified cytokines and chemokines induced specifically by TMEV infection. Then, we identified strain-specific longitudinal cytokine profiles in serum during acute disease. Using stepwise regression analysis, we identified serum immune markers predictive for TMEV-induced neurological phenotypes of the acute phase, e.g., IL-9 for limb paralysis; and TNF-α, IL-1β, and MIP-1β for limb weakness. These findings indicate how temporal differences in immune responses are influenced by host genetic background and demonstrate the potential of serum biomarkers to track the neurological effects of viral infection.

Sleep, Positive Affect, and Circulating Interleukin-6 in Women With Temporomandibular Joint Disorder

OBJECTIVE

Systemic inflammation is commonly observed in idiopathic chronic pain conditions, including temporomandibular joint disorder (TMD). Trait positive affect (PA) is associated with lower inflammation in healthy controls, but those effects may be threatened by poor sleep. The associations between PA with proinflammatory cytokine activity and potential moderation by sleep in chronic pain are not known. We thus investigated the association between PA and circulating interleukin-6 (IL-6) and moderation of that association by sleep in a sample of women with TMD and sleep difficulties.

METHODS

Participants (n = 110) completed the insomnia severity index and provided blood samples at five intervals throughout an evoked pain testing session. They then completed a 14-day diary assessing sleep and affect, along with wrist actigraphy.

RESULTS

There was not a significant main effect of PA on resting or pain-evoked IL-6 (b = 0.04, p = .33). Diary total sleep time (b = -0.002, p = .008), sleep efficiency (b = -0.01, p = .005), sleep onset latency (b = 0.006, p = .010), and wake after sleep onset (b = 0.003, p = .033) interacted with PA to predict IL-6, such that PA inversely predicted IL-6 at higher levels of total sleep time and sleep efficiency and at lower levels of sleep onset latency and wake after sleep onset. Surprisingly, when sleep was poor, PA predicted greater IL-6.

CONCLUSIONS

The potential salutary effects of PA on resting IL-6 erode when sleep is poor, underscoring the importance of considering sleep in conceptual and intervention models of TMD.

Association of serum interleukin-6 and C-reactive protein with depressive and adjustment disorders in COVID-19 inpatients

Background

Immune mechanisms are part of the pathophysiology of mental disorders, although their role remains controversial. In depressive disorders a chronic low-grade inflammatory process is observed, with higher interleukin-6 (IL-6) values. Furthermore, in SARS-CoV2 infection, which is closely related to depressive disorders, there is a proinflammatory cascade of cytokines that causes systemic inflammation.

Methods

The present study evaluates the relationship between IL-6 and C-reactive protein (CRP) serum levels and the presence of depressive and adjustment disorders in a sample of 1851 patients admitted to hospital for SARS-CoV2 infection from March to November 2020. Concentrations of IL-6 and CRP were determined within the first 72 ​h at admission and compared among groups of patients according to previous history and current presence of depression or adjustment disorders.

Results

IL-6 serum levels were significantly higher in the group of patients with depression and adjustment disorders compared to patients without such disorders (114.25 ​pg/mL (SD, 225.44) vs. 86.41 (SD, 202.97)), even after adjusting for several confounders. Similar results were obtained for CRP (103.94 ​mg/L (SD, 91.16) vs. 90.14 (SD, 85.73)). The absolute levels of IL-6 and CRP were higher than those of previous depression studies, and differences were only found for the subgroup of De Novo depressive or adjustment disorders.

Conclusions

Serum concentrations of IL-6 and CRP are higher in COVID-19 patients with De Novo but not persistent depressive or adjustment disorders. Clinical features such as fatigue, asthenia, anhedonia, or anxiety can be the basis for this finding.

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Inflammation markers are higher in COVID inpatients with affective symptoms and no previous psychiatric history.

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Sickness behavior overlaps with stress-related disorders symptomatology.

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Cytokine levels equalize in non-depressed and chronically depressed COVID inpatients.

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COVID inpatients with affective symptoms may show a worse prognosis.

From childhood maltreatment to adult inflammation: Evidence for the mediational status of social anxiety and low positive affect

Prior work has established a robust association between childhood maltreatment and systemic inflammatory activation later in life; however, the mechanisms involved in this process remain incompletely understood. The purpose of this investigation was to examine potential mechanistic roles for social anxiety (SA) symptoms and low positive affect (PA) in the path from childhood maltreatment to elevations in circulating interleukin (IL)-6, a common biomarker of inflammatory activation. In addition, building on prior work establishing linkages between mindful awareness and reductions in systemic inflammation, we examined the potential role of trait mindfulness as a moderator of the relationships among childhood maltreatment, SA, low PA, and IL-6. A serial mediation model utilizing a large epidemiologic dataset (final N ​= ​527) supported our central hypothesis that the direct effect of childhood maltreatment on IL-6 was fully serially statistically mediated by SA symptoms and low PA (but not high negative affect). Additionally, results indicated that individuals falling in the upper versus lower quartiles of SA symptoms demonstrated significantly elevated concentrations of IL-6, a finding that has not been previously reported. Trait mindfulness moderated the association between low PA and IL-6, to the exclusion of any paths related to negative affect. Additionally, results indicated that the effect of child maltreatment on IL-6 bypasses SA to indirectly impact IL-6 via negative affect. Overall, we conclude that childhood maltreatment and SA symptoms have a significant influence on IL-6, albeit indirectly via low PA, and the influence of PA on IL-6 may be uniquely susceptible to influence by individual differences in mindfulness.

General Psychosocial Measures are Affected by the Situation Preceding Assessment: The ‘Arbitrary Distinction’ Between State and Trait Measures is Still Unresolved

General psychosocial measures are assumed to be stable over time. However, such measures may be affected by the situation preceding assessment. In this study 28 participants completed the WHO-5 Well-Being Index, the Subjective Happiness Scale, and the Life Orientation Test which are general measures, and the Positive Affect Negative Affect Schedule and the Feeling Scale which are state measures. Subsequently, the first part of ‘Mega Disasters Nagasaki The Forgotten Bomb’ documentary was presented to the participants. Following the intervention, they completed the same measures again. State measures of negative affect increased, feeling state decreased as expected, but retrospectively measured well-being as well as the index of optimism also decreased. There were large individual differences. The findings indicate that general measures, assumed to be stable over time, are influenced by the situation. Therefore, there is a need for reporting, as well as controlling, the events preceding their measurement. The implication of these findings is that hundreds of empirical results based on general or trait measures may be invalid if any event preceding their assessment had an emotional impact.

Sickness and sleep health predict frustration and affective responses to a frustrating trigger

Fluctuations in health and sleep are common, but we know surprisingly little about how these daily life stressors affect one's level of frustration and sensitivity to becoming frustrated. In this pre-registered study, 517 participants (Mage = 30.4, SD = 10.4) reported their current sickness symptoms, health status, sleepiness, and sleep duration and quality the previous night. They also rated their general frustration and mood before and after a mild frustration-eliciting task. In the task, participants were instructed to copy geometric shapes onto a piece of paper, without lifting the pen from the paper. Participants were given three minutes to copy the eight shapes, but in order to induce frustration half of them were unsolvable. The study was subsequently repeated in an independent sample (N = 113). Frustration increased in response to the task; however, those with the worst sickness symptoms or sleep health reduced or did not change their frustration levels. Instead, across both studies, frustration was already high at baseline for these individuals. These findings indicate that being sick or having poor sleep is related to high general frustration, but resilience to further frustration due to mild frustrating situations.

Comparison of host immune responses to LPS in human using an immune profiling panel, in vivo endotoxemia versus ex vivo stimulation

Patients that suffer from sepsis exhibit an early hyper-inflammatory immune response which can lead to organ failure and death. In our study, we assessed the immune modulation in the human in vivo endotoxemia model and compared it to ex vivo LPS stimulation using 38 transcriptomic markers. Blood was collected before and after 4 hours of LPS challenge and tested with the Immune Profiling Panel (IPP) using the FilmArray system. The use of IPP showed that markers from the innate immunity dominated the response to LPS in vivo, mainly markers related to monocytes and neutrophils. Comparing the two models, in vivo and ex vivo, revealed that most of the markers were modulated in a similar pattern (68%). Some cytokine markers such as TNF, IFN-γ and IL-1β were under-expressed ex vivo compared to in vivo. T-cell markers were either unchanged or up-modulated ex vivo, compared to a down-modulation in vivo. Interestingly, markers related to neutrophils were expressed in opposite directions, which might be due to the presence of cell recruitment and feedback loops in vivo. The IPP tool was able to capture the early immune response in both the human in vivo endotoxemia model, a translational model mimicking the immune response observed in septic patients.

Positive and Negative Affect and Salivary Markers of Inflammation Among Young Adults

BACKGROUND

Emerging evidence suggests that higher circulating levels of inflammatory biomarkers in blood are associated with higher negative affect (NA) and lower positive affect (PA). To our knowledge, the unique associations between NA and PA in daily life and salivary biomarkers of inflammation have not been examined. This study examined these associations in young adults.

METHODS

Measures of NA and PA were created from aggregated daily measures of affect (morning and evening ratings averaged across 14 days). We investigated associations between these measures and salivary C-reactive protein (CRP) and interleukin (IL)-6 in a sample of 108 young adults (60% female, mean age = 20.45 ± 1.47), a subset of whom had self-reported chronic back pain (n = 49). CRP and IL-6 were determined from saliva obtained at the end of the daily diary period.

RESULTS

After covarying for age, gender, body mass index, chronic pain status, salivary flow rate, and NA, higher PA was associated with lower salivary CRP (β = - 0.02, 95% CI (- 0.03, - 0.00) sr2 = .06, p = .01) but not IL-6; removing NA from this model did not change results. In a model with the same covariates (and PA), NA was not significantly related to CRP or IL-6. Chronic back pain status and gender did not moderate results.

CONCLUSIONS

Findings suggest that higher PA may be associated with lower salivary CRP in young adults, even after accounting for NA and demographic characteristics. Findings highlight the utility of assessing emotional states in relation to salivary markers of inflammation in future biobehavioral research.

Family-based analyses reveal novel genetic overlap between cytokine interleukin-8 and risk for suicide attempt

BACKGROUND

Suicide is major public health concern. It is imperative to find robust biomarkers so that at-risk individuals can be identified in a timely and reliable manner. Previous work suggests mechanistic links between increased cytokines and risk for suicide, but questions remain regarding the etiology of this association, as well as the roles of sex and BMI.

METHODS

Analyses were conducted using a randomly-ascertained extended-pedigree sample of 1882 Mexican-American individuals (60% female, mean age = 42.04, range = 18-97). Genetic correlations were calculated using a variance components approach between the cytokines TNF-α, IL-6 and IL-8, and Lifetime Suicide Attempt and Current Suicidal Ideation. The potentially confounding effects of sex and BMI were considered.

RESULTS

159 individuals endorse a Lifetime Suicide Attempt. IL-8 and IL-6 shared significant genetic overlap with risk for suicide attempt (ρg = 0.49, pFDR = 7.67 × 10-03; ρg = 0.53, pFDR = 0.01), but for IL-6 this was attenuated when BMI was included as a covariate (ρg = 0.37, se = 0.23, pFDR = 0.12). Suicide attempts were significantly more common in females (pFDR = 0.01) and the genetic overlap between IL-8 and risk for suicide attempt was significant in females (ρg = 0.56, pFDR = 0.01), but not in males (ρg = 0.44, pFDR = 0.30).

DISCUSSION

These results demonstrate that: IL-8 shares genetic influences with risk for suicide attempt; females drove this effect; and BMI should be considered when assessing the association between IL-6 and suicide. This finding represents a significant advancement in knowledge by demonstrating that cytokine alterations are not simply a secondary manifestation of suicidal behavior, but rather, the pathophysiology of suicide attempts is, at least partly, underpinned by the same biological mechanisms responsible for regulating inflammatory response.

The Physical Burden of Immunoperception

The previous chapter introduced the ImmunoEmotional Regulatory System (IMMERS). Also, there was a brief discussion about psychological states/psychiatric disorders that so far have been linked to the IMMERS. The present chapter considers another aspect of the IMMERS in which physiological states/physical diseases can be fit to the IMMERS.

Resilience and immunity

Resilience is the process that allows individuals to adapt to adverse conditions and recover from them. This process is favored by individual qualities that have been amply studied in the field of stress such as personal control, positive affect, optimism, and social support. Biopsychosocial studies on the individual qualities that promote resilience show that these factors help protect against the deleterious influences of stressors on physiology in general and immunity in particular. The reverse is also true as there is evidence that immune processes influence resilience. Most of the data supporting this relationship comes from animal studies on individual differences in the ability to resist situations of chronic stress. These data build on the knowledge that has accumulated on the influence of immune factors on brain and behavior in both animal and human studies. In general, resilient individuals have a different immunophenotype from that of stress susceptible individuals. It is possible to render susceptible individuals resilient and vice versa by changing their inflammatory phenotype. The adaptive immune phenotype also influences the ability to recover from inflammation-induced symptoms. The modulation of these bidirectional relationships between resilience and immunity by the gut microbiota opens the possibility to influence them by probiotics and prebiotics. However, more focused studies on the reciprocal relationship between resilience and immunity will be necessary before this can be put into practice.

Sex differences in how inflammation affects behavior: What we can learn from experimental inflammatory models in humans

Human models demonstrate that experimental activation of the innate immune system has profound effects on brain activation and behavior, inducing fatigue, worsened mood and pain sensitivity. It has been proposed that inflammation is a mechanism involved in the etiology and maintenance of depression, chronic pain and long-term fatigue. These diseases show a strong female overrepresentation, suggesting that a better understanding of sex differences in how inflammation drives behavior could help the development of individualized treatment interventions. For this purpose, we here review sex differences in studies using experimental inflammatory models to investigate changes in brain activity and behavior. We suggest a model in which inflammation accentuates sex differences in brain networks and pre-existing vulnerability factors. This effect could render women more vulnerable to the detrimental effects of immune-to-brain communication over time. We call for systematic and large scale investigations of vulnerability factors for women in the behavioral response to inflammation.

Inflammation and depression: a causal or coincidental link to the pathophysiology?

This review summarises the evidence that chronic low grade inflammation triggers changes that contribute to the mental and physical ill health of patients with major depression. Inflammation, and the activation of the hypothalamic pituitary axis by stress, are normal components of the stress response but when stress is prolonged and the endocrine and immune system become chronic resulting in the activation of the peripheral macrophages, the central microglia and hypercortisolemia, the neuronal networks are damaged and become dysfunctional. The proinflammatory cytokines, in addition to activating the hypothalamic-pituitary-adrenal axis and thereby increasing cortisol synthesis, also activate the tryptophan-kynurenine pathway. This results in the synthesis of the neurotoxic N-methyl-d-aspartate (NMDA) glutamate agonist quinolinic acid and 3-hydroxykynurenine thereby enhancing oxidative stress and contributes to neurodegeneration which characterise major depression particularly in late life.While antidepressants attenuate some of the endocrine and immune changes caused by inflammation, not all therapeutically effective antidepressants do so. This suggests that drugs which specifically target the immune, endocrine and neurotransmitter systems may be more effective antidepressants.The preliminary clinical evidence that some non-steroidal anti-inflammatory drugs, such as the cyclooxygenase 2 inhibitor celecoxib, can enhance the response to standard antidepressant treatment is therefore considered and a critical assessment made of the possible limitations of such an approach to novel antidepressant development.

Emodiversity and biomarkers of inflammation

There is growing evidence that inflammatory responses may help to explain how emotions get "under the skin" to influence disease susceptibility. Moving beyond examination of individuals' average level of emotion, this study examined how the breadth and relative abundance of emotions that individuals experience-emodiversity-is related to systemic inflammation. Using diary data from 175 adults aged 40 to 65 who provided end-of-day reports of their positive and negative emotions over 30 days, we found that greater diversity in day-to-day positive emotions was associated with lower circulating levels of inflammation (indicated by IL-6, CRP, fibrinogen), independent of mean levels of positive and negative emotions, body mass index, anti-inflammatory medications, medical conditions, personality, and demographics. No significant associations were observed between global or negative emodiversity and inflammation. These findings highlight the unique role daily positive emotions play in biological health. (PsycINFO Database Record

PET Imaging in Psychoneuroimmunology Research

Positron-emission tomography (PET) imaging is a valuable research tool that enables in vivo quantification of molecular targets in the brain or of a physiologic process. PET imaging can be combined with various experimental and clinical model systems that are commonly used in psychoneuroimmunology research. As PET imaging can be used in animals and humans, promising results can therefore often be translated from an animal model to human disease.

If, Why, and When Subjective Well-Being Influences Health, and Future Needed Research

We review evidence on whether subjective well-being (SWB) can influence health, why it might do so, and what we know about the conditions where this is more or less likely to occur. This review also explores how various methodological approaches inform the study of the connections between subjective well-being and health and longevity outcomes. Our review of this growing literature indicates areas where data are substantial and where much more research is needed. We conclude that SWB can sometimes influence health, and review a number of reasons why it does so. A key open question is when it does and does not do so-in terms of populations likely to be affected, types of SWB that are most influential (including which might be harmful), and types of health and illnesses that are most likely to be affected. We also describe additional types of research that are now much needed in this burgeoning area of interest, for example, cross-cultural studies, animal research, and experimental interventions designed to raise long-term SWB and assess the effects on physical health. This research area is characterised both by potentially extremely important findings, and also by pivotal research issues and questions.

Sickness behavior in feverish children is independent of the severity of fever. An observational, multicenter study

BACKGROUND. OBJECTIVES

Behavioral changes in a febrile child are usually considered to stem from the fever. We studied sickness behavior (SB) in terms of its clinical components and its relation to fever.

METHODS

This observational, multicenter study included children aged 6 months to 3 years who were either febrile (fever ≥12 hours, ≥ 39°C and ≥38°C at inclusion) or non-febrile and well. The child had to have been awake for the 2 hours preceding the consultation and cared for by the parent who brought him/her to the doctor. SB was evaluated according to 6 parameters over this 2-hour period: time spent playing, distance covered, time spent seeking comfort, time spent whining or crying, time spent in a state of irritation or of anger, most distorted facial expression. Two parameters were assessed for the 24-hour period preceding the consultation: time spent sleeping and appetite. The parent reported the degree of change in these parameters compared with the usual situation, using rating scales.

RESULTS

200 febrile children (most with nonspecific upper respiratory infections) and 200 non-febrile children were included. The mean values of the 8 parameters differed significantly (p<0.001) between the 2 groups and were independent of the height of fever at inclusion in the febrile children. In the study conditions, paracetamol failed to improve SB when the child was still feverish.

CONCLUSION

The 8 parameters suggested that SB and fever are two independent manifestations that are activated simultaneously during an infection. This independence is in harmony with recommendations to treat the discomfort of SB and not the fever.

Towards an integrative picture of human sickness behavior

Sickness behavior, a coordinated set of behavioral changes during infection and elicited by the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β), is well studied in non-human animals. Over the last two decades, several papers have expanded this research to include humans. However, these studies use a variety of research designs, and typically focus on a single cytokine and only a few of the many behavioral changes constituting sickness behavior. Therefore, our understanding of human sickness behavior remains equivocal. To generate a more holistic, integrative picture of this phenomenon, a meta-analysis of the human sickness behavior literature was conducted. Full model results show that both IL-6 and IL-1β have significant relationships with sickness behavior, and the strength of these relationships is affected by a number of study parameters, such as type of immune stimulus and inclusion of controls. In addition to research design heterogeneity, other issues to address in future studies include an unequal focus on different cytokines and different sickness behaviors.

Socioeconomic status, daily affective and social experiences, and inflammation during adolescence

OBJECTIVE

To assess the relation between socioeconomic status (SES) and inflammation during adolescence and determine whether daily affective and social experiences across a 15-day period mediate this relation.

METHODS

Adolescents (n = 316) completed daily diary reports of positive affect, negative affect, and negative social interactions for 15 days and provided whole blood spot samples for the assessment of C-reactive protein (CRP). Parents provided information on SES, including the highest level of education they and their spouses completed and household income.

RESULTS

Lower parent education was associated with higher levels of adolescent CRP, controlling for age, sex, ethnicity, and body mass index (β = -.12, p = .031). Mean daily positive affect, negative affect, and negative social interactions were examined as potential mediators of this association. In these models, parent education was no longer associated with adolescent CRP (β = -.09, p = .12), and only positive affect was related to CRP (β = -.12, p = .025). Bootstrapping confirmed the mediating role of positive affect (indirect effect = -0.015, 95% confidence interval = -0.038 to -0.002).

CONCLUSIONS

Adolescents with less educated parents tended to have higher levels of CRP, which may be explained by their lower levels of positive affect. Findings suggest that a lack of positive affect may be a pathway by which SES confers early risk for poor health in adulthood. It is possible that adolescents who display positive affect during daily life in circumstances of relatively adverse socioeconomic circumstances may have better health outcomes related to lower inflammatory factors.

Bu-zhong-yi-qi pill alleviate the chemotherapy-related fatigue in 4 T1 murine breast cancer model

Background

Paclitaxel induced fatigue still remains underrecognized and undertreated, partly because of limited understanding of its pathophysiology and lack of effective treatments. This study is aim to evaluate the anti-fatigue effects and mechanism of Bu-Zhong-Yi-Qi pill in murine 4 T1 breast cancer mice were treated with paclitaxel.

Methods

Breast cancer mice established with murine 4 T1 cells were randomly and repectively divided into five groups: negative control group (NC), tumor control group (TC), paclitaxel group (PTX), Bu-Zhong-Yi-Qi pill group (BZYQ) and Bu-Zhong-Yi-Qi pill plus paclitaxel group (BZYQ + PTX). The mice were administered for 21 days. During this period, the tumor volume, body weight and the weight-loaded swimming time were measured. After the last administration, all mice were sacrificed, weighted the tumor, measured immune cell cytokines and oxidative stress indicator. The remaining 10 mice in each group were observed for survival analysis.

Results

Treatments with BZYQ + PTX and PTX significantly reduced the rates of tumor volume in comparison with TC starting on the 9th day and the 18th day respectively (P < 0.05-0.01), and presented decreased tumor weight compared to TC (P < 0.05-0.01). Compared with mice in TC group, the median survival time and the average survival time in BZYQ + PTX group, BZYQ group and PTX group were significantly prolonged (P < 0.05-0.01). The swimming time of the BZYQ + PTX group gradually increased, which is longer than the PTX group on Day 14 and Day 21 (P < 0.01). The level of TNF-α was lower in BZYQ + PTX group than PTX group (P < 0.01). The level of SOD activity in BZYQ + PTX group was lower than the NC group (P <0.01), but much higher than the PTX group (P < 0.01). The level of MDA of BZYQ + PTX group was higher than the NC group (P < 0.01), but significant lower than the PTX group (P < 0.01).

Conclusions

BZYQ has the potential of alleviating paclitaxel chemotherapy-related fatigue in 4 T1 breast cancer mice by reducing the serum levels of TNF-α and modulating the level of MDA and the SOD activity.

Mood disturbance after infection

OBJECTIVE

An aetiological link between acute infection and major depression has long been hypothesized, and is increasingly gaining recognition within contemporary literature. This review aims to examine the evidence for such a link, specifically between acute, self-limiting infection and major depression, and to summarize the current understanding of pathophysiological mechanisms underlying this link.

METHODS

Relevant articles were sourced via an online search of published literature from Embase, MEDLINE, PsycINFO and PubMed using a variety of search terms including mood disorder, depression, infection and inflammation. Additionally, a search for articles from the bibliographies of retrieved papers was conducted.

RESULTS

Findings from retrospective studies suggest an association between infection and subsequent mood disturbance, including major depression. This association has been confirmed by studies employing prospective observational or experimental challenge designs. The available evidence supports a multifactorial basis of vulnerability towards major depression in the context of acute infection. Genetic, neuroendocrine, autonomic and psychosocial factors may interact to potentiate the likelihood of a severe and prolonged depressive response to an immunological stressor in some individuals.

CONCLUSION

Mood disturbance is likely to have a host-protective role in the context of an acute sickness response to infection. However, this usually adaptive and reversible response may progress in some vulnerable individuals into a more sustained and severe pattern of behavioural and physiological changes of major depression. Further research is needed to delineate the factors that predispose, precipitate and perpetuate depression in the context of acute infective illness. Such insights will inform effective prevention and treatment strategies.

The application of PET imaging in psychoneuroimmunology research

Positron emission tomography (PET) imaging is a research tool that allows in vivo measurements of brain metabolism and specific target molecules. PET imaging can be used to measure these brain variables in a variety of species, including human and non-human primates, and rodents. PET imaging can therefore be combined with various experimental and clinical model systems that are commonly used in psychoneuroimmunology research.

Imipramine reverses depressive-like parameters in pneumococcal meningitis survivor rats

Pneumococcal meningitis is a severe infectious disease of the central nervous system, associated with acute inflammation and might cause damage to the host, such as deafness, blindness, seizure, and learning deficits. However, infectious diseases can play a significant role in the etiology of neuropsychiatric disturbances. In this context, we evaluated depressive-like parameters; corticosterone and ACTH levels in pneumococcal meningitis surviving rats. Wistar rats underwent a magna cistern tap receiving either 10 μL sterile saline or a Streptococcus pneumoniae suspension at the concentration of 5 × 10(9) cfu/mL. After 3 days of meningitis induction procedure, the animals were treated with imipramine at 10 mg/kg or saline for 14 days (3rd-17th day). The consumption of sweet food was measured for 7 days (10th-17th day). The meningitis group decreased the sucrose intake and increased the levels of corticosterone and ACTH levels in the serum and TNF-α in the cortex; however, the treatment with imipramine reverted the reduction of sweet food consumption, normalized hormonal levels and TNF-α in the cortex. Our results supported the hypothesis that the pneumococcal meningitis surviving rats showed depressive-like behavior and alterations in the hypothalamus-pituitary-adrenal axis.

C-reactive protein haplotypes and dispositional optimism in obese and nonobese elderly subjects

Background

Chronic low-grade inflammation, characterized by elevated plasma levels of C-reactive protein (CRP), has been inversely associated with dispositional optimism. Using a Mendelian randomization design, this study explores whether CRP haplotypes that determine CRP plasma levels are also associated with dispositional optimism.

Methods

In a sample of 1,084 community-dwelling subjects (aged 60–85 years) from three cohort studies (Arnhem Elderly Study, n = 426; Leiden Longevity Study, n = 355; Zutphen Elderly Study, n = 303), six CRP polymorphisms (rs2808628, rs2808630, rs1205, rs1800947, rs1417938, and rs3091244) coding for five common haplotypes were genotyped. The association of CRP haplotypes with CRP plasma levels and dispositional optimism was analyzed using multivariable linear regression models. Subanalyses were stratified by body mass index (BMI ≥25 kg/m²).

Results

CRP haplotypes determined CRP plasma levels (adjusted β = 0.094, p < 0.001). In the whole group, no association was found between CRP haplotypes and dispositional optimism scores (adjusted β = −0.02, p = 0.45). In BMI strata, CRP haplotypes were associated with increasing levels of plasma CRP levels (adjusted β = 0.112; p = 0.002) and lower dispositional optimism levels (adjusted β = −0.068; p = 0.03) in the obese group only.

Conclusions

These results suggest that genetically increased CRP levels are involved in low dispositional optimism, but only in case of obesity.

The keys to improving depression outcomes

The heterogeneity of symptoms within major depressive disorder poses significant challenges for treatment and it is likely that current pharmacotherapies do not target all symptoms equally, although they have similar efficacy rates. While there is still continuing interest in understanding monoamine interactions and consequent downstream effects, the limited efficacy and tolerability achieved with classical antidepressants provides a compelling argument to move beyond the monoamines. Several lines of biological research in depression exploring immune function, neurotrophins, amino acid and neuropeptide neurotransmitters, neuroanatomical function and circadian rhythms, may lead to novel therapeutic targets and enhance depression outcomes. This review will evaluate the evidence for emerging treatments as well as recommendations from current international guidelines regarding antidepressant management.

Is positive affect associated with survival? A population-based study of elderly persons

Study results on the association of positive affect with survival are conflicting. This disagreement potentially arises from poor control for health or negative affect and for the various age groups studied. The authors examined if positive affect predicts survival; whether this association is preserved after controlling for negative affect, socioeconomic status, lifestyle, and health; and whether this association varies with age. The study is set within the population-based Rotterdam Study (1997-2007) and included 4,411 participants aged 61 years or older, followed for on average 7.19 (standard deviation = 2.20) years. Positive affect was not consistently associated with survival across all ages. A significant interaction of positive affect with age on survival (P = 0.02) was found. Subsequent age stratification revealed that positive affect independently predicted survival in elderly persons aged <80 years (per affect score, hazard ratio = 0.96, 95% confidence interval: 0.93, 0.99) but not in those aged ≥80 years in fully adjusted models (hazard ratio = 1.00, 95% confidence interval: 0.96, 1.04). In the oldest old, the association was partly explained by differences in baseline health. In conclusion, the results suggest that there may be an association of positive affect with survival in the younger and middle old but not in the oldest old in whom perception of positive affect is more likely to be determined by health.

Cytokine levels at a single time point following a reminder stimulus among women in abusive dating relationships: Relationship to emotional states

Stressful events and reminders of such events may influence circulating cytokine levels, just as they influence several neuroendocrine processes. However, these cytokine changes may vary with the severity and chronicity of the stressor experienced, as well as the specific mood responses that participants express. In the present investigation, women in abusive or non-abusive dating relationship (N=75) read a script about an abusive or non-abusive relationship and then reported their mood states, followed by the collection of a single blood sample 30 min later. The abused women who read the abuse-related script reported greater anger, sadness, shame, and anxiety than did the non-abused women. In non-abused women greater levels of anger and sadness, but not shame or anxiety, were associated with higher levels of the proinflammatory cytokine, interleukin-6 (IL-6), as well as the anti-inflammatory cytokine, IL-10, irrespective of whether they had read a script regarding an abusive relationship or a neutral script. In contrast, among abused women shown a neutral script, neither IL-6 nor IL-10 levels were related to their anger and sadness, whereas mood levels following the reading of a script regarding abuse were directly related to IL-6, although the extent of the association was lower than that evident in non-abused women. Levels of IL-10 in the abused women, unlike their non-abused counterparts, did not vary with mood state. These data suggest that cytokine levels and the relative balance of IL-6 and IL-10 ordinarily are associated with specific moods, but this relationship is not apparent among women in a chronic stress state.

Positive affect and inflammation during radiation treatment for breast and prostate cancer

There is growing evidence that positive affect may influence health and immune function, although few studies have examined links between positive affect and immune processes in clinical populations. The purpose of this study was to examine whether positive affect is associated with changes in proinflammatory cytokines in cancer patients undergoing radiation treatment. Subjects were 50 individuals with early-stage breast and prostate cancer who completed psychosocial questionnaires and provided blood samples at seven time points before, during, and after radiation treatment. Positive affect was assessed before treatment onset using the CES-D (Center for Epidemiological Studies Depression Scale). Blood samples were assayed for serum levels of proinflammatory cytokines IL-1beta and IL-6. Patients with higher levels of positive affect before treatment exhibited higher mean levels of IL-1beta and IL-6 during radiation treatment (all ps<.05). Results suggest that positive affect enhances the acute inflammatory response to radiation treatment, perhaps facilitating tissue repair processes.

A critical review of human endotoxin administration as an experimental paradigm of depression

The syndrome called depression may represent the common final pathway at which different aetiopathogenic processes converge. One such aetiopathogenic process is innate immune system activation. Some depressed patients have increased levels of inflammatory cytokines and other immunologic abnormalities. It is not known whether immune system activation contributes to the pathogenesis of depressive symptoms. Supporting this possibility is the observation that in both rodents and humans, exogenous immune stimuli such as endotoxin can produce symptoms that resemble depression. A new approach to depression research would be to use immune stimuli to elicit depressive symptoms in humans. Here we review each of the symptoms elicited in humans by endotoxin administration, and compare this model to two other immune depression paradigms: interferon-alpha treatment and typhoid vaccine administration, to assess to what degree endotoxin administration represents a valid model of immune depression. We also review corresponding behavioral changes in rodents and the potential molecular pathways through which immune system activation produces each symptom.

Dispositional optimism and stress-induced changes in immunity and negative mood

Evidence suggests that optimism may be protective for health during times of heightened stress, yet the mechanisms involved remain unclear. In a double-blind placebo-controlled study, we recently showed that acute psychological stress and an immune stimulus (Typhim-Vi typhoid vaccine) synergistically increased serum levels of interleukin-6 (IL-6) and negative mood in 59 healthy men. Here we carried out further analysis of this sample to investigate the relationship between dispositional optimism and stress-induced changes in immunity and mood. Volunteers were randomly assigned to one of four experimental conditions in which they received either typhoid vaccine or saline placebo, and then rested or completed two mental tasks. In the stress condition, optimism was inversely related to IL-6 responses, independent of age, BMI, trait CES-D depression and baseline IL-6. This relationship was present across both stress groups (combining vaccine and placebo) and was not present in the vaccine/stress group alone, suggesting that optimism protects against the inflammatory effects of stress rather than vaccine per se. Typhoid vaccine induced a significant increase in participants' circulating anti-Vi antibody levels. Stress had no effect on antibody responses overall. However, in the vaccine/stress group, there was a strong positive association between optimism and antibody responses, indicating that stress accentuated the antibody response to vaccine in optimists. Across the complete sample, more optimistic individuals had smaller increases in negative mood and less reduction in mental vigour. Together these findings suggest that optimism may promote health, by counteracting stress-induced increases in inflammation and boosting the adjuvant effects of acute stress.

Inhibition of p38 MAPK suppresses inflammatory cytokine induction by etoposide, 5-fluorouracil, and doxorubicin without affecting tumoricidal activity

Cancer patients undergoing treatment with systemic cancer chemotherapy drugs often experience debilitating fatigue similar to sickness behavior, a normal response to infection or tissue damage caused by the production of the inflammatory cytokines IL-1β, TNF-α, and IL-6. The p38 mitogen activated protein kinase (p38 MAPK) plays a central role in the production of these cytokines and consequently the development of sickness behavior. Targeted inhibitors of p38 MAPK can reduce systemic inflammatory cytokine production and the development of sickness behavior. Several systemic cancer chemotherapy drugs have been shown to stimulate inflammatory cytokine production, yet whether this response is related to a common ability to activate p38 MAPK is not known and is the focus of this study. This understanding may present the possibility of using p38 MAPK inhibitors to reduce chemotherapy-induced inflammatory cytokine production and consequently treatment-related fatigue. One caveat of this approach is a potential reduction in chemotherapeutic efficacy as some believe that p38 MAPK activity is required for chemotherapy-induced cytotoxicity of tumor cells. The purpose of this study was to demonstrate proof of principal that p38 MAPK inhibition can block chemotherapy- induced inflammatory cytokine production without inhibiting drug-induced cytotoxicity using murine peritoneal macrophages and Lewis Lung Carcinoma (LLC1) cells as model cell systems. Using these cells we assessed the requirement of etoposide, doxorubicin, 5-flourouracil, and docetaxel for p38 MAPK in inflammatory cytokine production and cytotoxicity. Study findings demonstrate that clinically relevant doses of etoposide, doxorubicin, and 5-FU activated p38 MAPK in both macrophages and LLC1 cells. In contrast, docetaxel failed to activate p38 MAPK in either cell type. Activation of p38 MAPK mediated the drug's effects on inflammatory cytokine production in macrophages but not LLC1 cytotoxicity and this was confirmed with inhibitor studies.

Does chronic stress lead to increased rates of recurrences of genital herpes - a review of the psychoneuroimmunological evidence?

Summary:

It is a commonly expressed expert view that stress is associated with frequent recurrences of genital herpes (GH) but the evidence for this is poor and it is often asserted that stress is the result of GH rather than any other cause. We have reviewed the recent literature on this topic, restricting evidence to only prospective studies. We have further combined and integrated this evidence with both human and animal work in the psychoneuroimmunological field to come up with suggestive evidence that recurrence rates of GH are indeed associated with antecedent chronic stress/depression, whatever might be the cause. We further discuss the psychoneuroimmunological underpinning of the systemic features of the recurrent GH prodrome. Recommendations about holistic management of recurrent GH that include both pharmacological and psychological therapies are given.

Marital quality and the marital bed: examining the covariation between relationship quality and sleep

The majority of adults sleep with a partner, and for a significant proportion of couples, sleep problems and relationship problems co-occur, yet there has been little systematic study of the association between close relationships and sleep. The association between sleep and relationships is likely to be bi-directional and reciprocal-the quality of close relationships influences sleep and sleep disturbances or sleep disorders influence close relationship quality. Therefore, the purpose of the present review is to summarize the extant research on (1) the impact of co-sleeping on bed partner's sleep, (2) the impact of sleep disturbance or sleep disorders on relationship functioning, and (3) the impact of close relationship quality on sleep. In addition, we provide a conceptual model of biopsychosocial pathways to account for the covariation between relationship functioning and sleep. Recognizing the dyadic nature of sleep and incorporating such knowledge into both clinical practice and research in sleep medicine may elucidate key mechanisms in the etiology and maintenance of both sleep disorders and relationship problems and may ultimately inform novel treatments.

Correlation of psychological and physical symptoms with chronically elevated cytokine levels associated with a common immune dysregulation

BACKGROUND

Chronically elevated levels of proinflammatory cytokines are associated with inflammatory diseases and psychological symptoms of depression and tiredness.

OBJECTIVE

To test the prediction that, in a healthy population without medically diagnosed diseases, psychological symptoms (depression and tiredness) associated with proinflammatory cytokines correlate with physical symptoms associated with inflammatory disease.

METHODS

A total of 1,143 women between 45 and 65 years old completed a health complaint checklist containing 11 target symptoms (5 related to allergy, 4 to gastrointestinal symptoms, and 2 to pain), 7 control symptoms or health complaints, and 2 psychological symptoms (depression and tiredness). They also completed a menopausal quality-of-life questionnaire; to compensate for response bias, we removed variance attributable to quality of life.

RESULTS

The partial correlations show that tiredness (but not depression) correlated with 9 of the 11 target symptoms (P < .001) but with 0 of the 7 control symptoms or complaints. Symptoms of both the specific and the systemic components of inflammatory disease are correlated in a healthy population.

CONCLUSION

Immune dysregulation may explain the existence and covariation of psychological and physical symptoms in the healthy population, including people with medically unexplained symptoms.

Positive affective style covaries with stimulated IL-6 and IL-10 production in a middle-aged community sample

An emerging literature indicates that dispositional positive affect (PA) may play a protective role in health and render individuals less susceptible to inflammatory diseases. In this regard, it has been suggested that PA is associated with diminished activation of innate immune pathways. To explore this possibility, we examined relationships between trait positive emotional style, as assessed by the Positive and Negative Affect Schedule, and monocyte-derived lipopolysaccharide-induced production of the pro- and anti-inflammatory cytokines, interleukin (IL)-6, IL-1beta, TNF-alpha, and IL-10, among 146 healthy adults aged 30-54. After controlling for demographic factors and other covariates (age, gender, race, body mass index and white blood cell count), hierarchical regression analyses revealed an inverse association between trait PA and stimulated production of IL-6 (DeltaR(2)=.03, b=-.18, p <.04) and IL-10 (DeltaR(2)=.09; b =-.32, p <.01), with the latter association obtained only in men. No association was observed between trait PA and stimulated IL-1beta or TNF-alpha. Additionally, trait negative affect was unrelated to any of the stimulated cytokine levels. These initial findings suggest that individuals higher in trait positive emotional style show decreased in vitro production of the early inflammatory mediators IL-6 and IL-10 in response to stimulation with endotoxin which may confer protection against the emergence and progression of inflammatory diseases. Further exploration of this potential psychophysiological pathway is warranted.