Sex differences in the interleukin-6 response to acute psychological stress

Hormonal contraceptive use is associated with differences in women's inflammatory and psychological reactivity to an acute social stressor

Women using hormonal contraceptives (HCs) exhibit numerous signs of chronic inflammation, including elevated C-reactive protein levels and greater risk of developing mood and autoimmune disorders. However, users and non-users of HCs often have similar circulating proinflammatory cytokine levels, making the mechanism of association unclear. One possible explanation for this paradox is that HC users exhibit differences in their inflammatory responses to psychosocial stress that, over time, could contribute to chronic inflammation and its pathologies. Here, we tested this possibility by examining women's glucocorticoid, inflammatory, and psychological responses to the Trier Social Stress Test (TSST) in 67 naturally cycling (NC) and 60 oral HC-using women (Mage = 19.31, SDage = 1.95). As hypothesized, HC users and NC women exhibited different glucocorticoid and proinflammatory cytokine responses to the TSST. For NC women, TSST-induced increases in glucocorticoids were uncommon, and increases in glucocorticoids were accompanied by elevations in IL-6. In contrast, for women using HCs, increases in glucocorticoids in response to the TSST were common, and increases in glucocorticoids were accompanied by increases in TNF-α. HC users and NC women also differed in their psychological responses to the TSST, with HC users reporting elevated stress levels compared to NC women. Together, these results suggest that HC use impacts women's glucocorticoid, inflammatory, and psychological responses to psychosocial stress, potentially contributing to observed differences in these women's mental and physical health.

Levels of IL-6 are Associated with Lifetime Attempted Suicide in Alcohol Use Disorder Patients

Background

Patients with alcohol use disorder (AUD) have an increased risk of suicide. Neuroimmunological measures, such as cytokines, are shown to deviate in people with attempted suicide. Few studies have investigated this among AUD patients.

Patients and Methods

One-hundred and fourteen patients undergoing residential treatment for AUD were interviewed on lifetime suicide attempts (SA) along with several other background variables and clinical characteristics. Serum blood samples were drawn for analysis of cytokines.

Results

Thirty-one patients (27%) reported at least one SA. These patients had more symptoms of current affective disorders and more severe dependence. In bivariate analysis only IL-6 and IL-10 appeared to be associated with lifetime SA but without reaching statistical significance. In multivariate linear regression, adjusting for sex, nicotine use, somatic illness, and the use of anti-inflammatory drugs, IL-6 was associated to SA (p = 0.033).

Conclusion

The cytokine IL-6 has repeatedly been found to be associated with suicidality. The present study concurs with this role of IL-6 in a naturalistic observational study of AUD patients.

Glycoprotein acetyls and depression: Testing for directionality and potential causality using longitudinal data and Mendelian randomization analyses

BACKGROUND

Inflammation is associated with depression, but causality remains unclear. We investigated potential causality and direction of effect between inflammation and depression.

METHODS

Using data from the ALSPAC birth cohort (n = 4021; 42.18 % male), we used multivariable regression to investigate bidirectional longitudinal associations of GlycA and depression and depression symptoms, assessed at ages 18y and 24y. We used two-sample Mendelian randomization (MR) to investigate potential causality and directionality. Genetic variants for GlycA were obtained from UK Biobank (UKB) (N = 115,078); for depression from the Psychiatric Genomics Consortium and UKB (N = 500,199); and for depressive symptoms (N = 161,460) from the Social Science Genetic Association Consortium. In addition to the Inverse Variance Weighted method, we used sensitivity analyses to strengthen causal inference. We conducted multivariable MR adjusting for body mass index (BMI) due to known genetic correlation between inflammation, depression and BMI.

RESULTS

In the cohort analysis, after adjusting for potential confounders we found no evidence of associations between GlycA and depression symptoms score or vice versa. We observed an association between GlycA and depression (OR = 1∙18, 95 % CI: 1∙03-1∙36). MR suggested no causal effect of GlycA on depression, but there was a causal effect of depression on GlycA (mean difference in GlycA = 0∙09; 95 % CI: 0∙03-0∙16), which was maintained in some, but not all, sensitivity analyses.

LIMITATIONS

The GWAS sample overlap could incur bias.

CONCLUSION

We found no consistent evidence for an effect of GlycA on depression. There was evidence that depression increases GlycA in the MR analysis, but this may be confounded/mediated by BMI.

Gender Differences and Cardiometabolic Risk: The Importance of the Risk Factors

Metabolic syndrome (Mets) is a clinical condition characterized by a cluster of major risk factors for cardiovascular disease (CVD) and type 2 diabetes: proatherogenic dyslipidemia, elevated blood pressure, dysglycemia, and abdominal obesity. Each risk factor has an independent effect, but, when aggregated, they become synergistic, doubling the risk of developing cardiovascular diseases and causing a 1.5-fold increase in all-cause mortality. We will highlight gender differences in the epidemiology, etiology, pathophysiology, and clinical expression of the aforementioned Mets components. Moreover, we will discuss gender differences in new biochemical markers of metabolic syndrome and cardiovascular risk.

Multi-systemic evaluation of biological and emotional responses to the Trier Social Stress Test: A meta-analysis and systematic review

Humans experience multiple biological and emotional changes under acute stress. Adopting a multi-systemic approach, we summarized 61 studies on healthy people's endocrinological, physiological, immunological and emotional responses to the Trier Social Stress Test. We found salivary cortisol and negative mood states were the most sensitive markers to acute stress and recovery. Biomarkers such as heart rate and salivary alpha-amylase also showed sensitivity to acute stress, but the numbers of studies were small. Other endocrinological (e.g., dehydroepiandrosterone), inflammatory (C-Reactive Protein, Interleukin-6) and physiological (e.g., skin conductance level) measures received modest support as acute stress markers. Salivary cortisol showed some associations with mood measures (e.g., state anxiety) during acute stress and recovery, and heart rate showed preliminary positive relationship with calmness ratings during response to TSST, but the overall evidence was mixed. While further research is needed, these findings provide updated and comprehensive knowledge on the integrated psychobiological response profiles to TSST.

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

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

Potential Factors That Contribute to Post-COVID-19 Fatigue in Women

Mortality of acute coronavirus disease (COVID-19) is higher in men than in women. On the contrary, women experience more long-term consequences of the disease, such as fatigue. In this perspective article, we proposed a model of the potential factors that might contribute to the higher incidence of post-COVID-19 fatigue in women. Specifically, psycho-physiological factors are features that might increase central factors (e.g., inflammation) and result in greater perceptions of fatigue. Furthermore, pre-existing conditions likely play a prominent role. This model offers a framework for researchers and clinicians, and future research is required to validate our proposed model and elucidate all mechanisms of the increased incidence and prevalence of post-COVID-19 fatigue in women.

Effects of an intravenous ketamine infusion on inflammatory cytokine levels in male and female Sprague-Dawley rats

Background

Ketamine, a multimodal dissociative anesthetic drug, is widely used as an analgesic following traumatic injury. Although ketamine may produce anti-inflammatory effects when administered after injury, the immunomodulatory properties of intravenous (IV) ketamine in a non-inflammatory condition are unclear. In addition, most preclinical studies use an intraperitoneal (IP) injection of ketamine, which limits its clinical translation as patients usually receive an IV ketamine infusion after injury.

Methods

Here, we administered sub-anesthetic doses of a single IV ketamine infusion (0, 10, or 40 mg/kg) to male and female Sprague–Dawley rats over a 2-h period. We collected blood samples at 2- and 4-h post-ketamine infusion to determine plasma inflammatory cytokine levels using multiplex immunoassays.

Results

The 10 mg/kg ketamine infusion reduced spontaneous locomotor activity in male and female rats, while the 40 mg/kg infusion stimulated activity in female, but not male, rats. The IV ketamine infusion produced dose-dependent and sex-specific effects on plasma inflammatory cytokine levels. A ketamine infusion reduced KC/GRO and tumor necrosis factor alpha (TNF-α) levels in both male and female rats, interleukin-6 (IL-6) levels in female rats, and interleukin-10 (IL-10) levels in male rats. However, most cytokine levels returned to control levels at 4-h post-infusion, except for IL-6 levels in male rats and TNF-α levels in female rats, indicating a different trajectory of certain cytokine changes over time following ketamine administration.

Conclusions

The current findings suggest that sub-anesthetic doses of an IV ketamine infusion may produce sex-related differences in the effects on peripheral inflammatory markers in rodents, and further research is warranted to determine potential therapeutic effects of an IV ketamine infusion in an inflammatory condition.

Sex differences in the inflammatory response to stress and risk of adverse cardiovascular outcomes among patients with coronary heart disease

Stress may contribute to progression of coronary heart disease (CHD) through inflammation, especially among women. Thus, we sought to examine whether increased inflammatory response to stress among patients with CHD is associated with a greater risk of cardiovascular events and whether this risk is higher in women. We examined inflammatory biomarkers known to increase with mental stress (speech task), including interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and matrix metallopeptidase-9 (MMP-9) among 562 patients with stable CHD. Inflammatory response, the difference between post-stress and resting values, was examined as a predictor of major adverse cardiovascular events (MACE) using subdistribution hazards models for competing risks adjusting for demographics, cardiovascular risk factors, and medications. MACE was defined as a composite endpoint of cardiovascular death, myocardial infarction, unstable angina with revascularization, and heart failure. All biomarkers were standardized. The mean age was 63 years (range 34-79) and 24% were women. During a median follow-up of 3 years, 71 patients experienced MACE. Overall, there was no significant association between inflammatory response to stress and risk of MACE, but there were sex-based interactions for IL-6 (p = 0.001) and MCP-1 (p = 0.01). The risk of MACE increased 56% (HR: 1.56; 95% CI: 1.21, 2.01; p = 0.001) and 30% (HR: 1.30; 95% 1.09, 1.55; p = 0.004) for each standard deviation increase in IL-6 and MCP-1 response to mental stress for women, respectively, while there was no association among men. Increased inflammation in response to stress is associated with future adverse cardiovascular outcomes among women with CHD.

Stress-related suppression of peripheral cytokines predicts future relapse in alcohol-dependent individuals with and without subclinical depression

Chronic alcohol abuse and depressive symptoms are both associated with peripheral cytokine changes. Despite this, cytokine adaptations have not been assessed in co-morbid populations or prospectively as predictors of relapse. We examine cytokine responses to stress in alcohol-dependent individuals and social drinkers, both with and without subclinical depression. We also examine the potential link between cytokine adaptations in response to stress and prospective alcohol relapse risk. Thirty-three, alcohol-dependent individuals (21 with and 12 without high depressive symptoms) and 37 controls (16 with and 21 without high depressive symptoms) were exposed to two 5-minute personalized guided imagery conditions (stress and neutral) across consecutive days in a randomized and counterbalanced order. Alcohol craving and serum measures of tumor necrosis factor alpha (TNFα), tumor necrosis factor receptor 1 (TNFR1), interleukin-6 (IL-6), and interleukin-1 receptor antagonist (IL-1ra) were collected prior to and following imagery exposure. Following treatment discharge, follow-up interviews were conducted over 90 days to assess relapse. Dampened IL-1ra and IL-6 in response to stress was observed as a function of alcohol dependence and not moderated by depressive symptoms. Lower levels of IL-6 following stress also predicted greater drinking days following treatment. Conversely, high depressive symptomatology was associated solely with pro-inflammatory adaptations. Stress-related suppression of TNFα predicted drinking severity only in alcohol-dependent individuals with subclinical depression, and suppressed TNFR1 following stress was only seen in individuals with subclinical depression. Stress-induced suppression of pro-inflammatory TNF markers may indicate a risk factor for alcohol-dependent individuals with co-occurring depressive symptoms.

Health Disparities in COVID-19: Addressing the Role of Social Determinants of Health in Immune System Dysfunction to Turn the Tide

It is evident that health disparities exist during the COVID-19 pandemic, a pandemic caused by the novel coronavirus SARS-CoV-2. Underlying reasons for COVID-19 health disparities are multi-factorial. However, social determinants, including those regarding socioeconomic status, social inequalities, health behaviors, and stress, may have implications on these disparities. Exposure to one or more of these social determinants is associated with heightened inflammatory responses, particularly increases in the cytokine interleukin-6 (IL-6), as well as immune system dysfunction. Thus, an amplified effect during COVID-19 could occur, potentially resulting in vulnerable patients experiencing an intensified cytokine storm due to a hyperactive and dysfunctional immune response. Further understanding how social determinants play a mechanistic role in COVID-19 disparities could potentially help reduce health disparities overall and in future pandemics.

Sex Differences in the Inflammatory Consequences of Stress: Implications for Pharmacotherapy

Women are at significantly greater risk of developing stress-related disorders such as depression. The increased risk begins during puberty and continues throughout life until menopause, suggesting a role for ovarian hormones in this increased susceptibility. Importantly, inflammation has been gaining momentum in its role in the pathogenesis of depression. Herein, clinical and preclinical studies have been reviewed to better understand how sex differences within the immune system may contribute to exaggerated risk of depression in females. First, studies that investigate the ability of psychologic stress episodes to engage the inflammatory systems both in the brain and periphery are reviewed with a special focus on sex-specific effects. Moreover, studies are discussed that identify whether imbalanced inflammatory milieu contributes to the development of depression in males versus females and whether these effects are regulated by estradiol. Importantly, we propose a locus coeruleus-norepinephrine-cytokine circuit as a conduit through which stress could increase stress susceptibly in females. Finally, the anti-inflammatory capacity of traditional and nontraditional antidepressants is investigated, with the goal of providing a better understanding of pharmacotherapeutics to enhance strategies to personalize antidepressant treatments between the sexes. The studies reviewed herein strongly support the need for further studies to elucidate whether females are especially sensitive to anti-inflammatory compounds as adjuvants to traditional therapies. SIGNIFICANCE STATEMENT: Women have hve an increased risk of developing stress-related disorders such as depression. In this review, literature from clinical and preclinical studies are integrated to define sex differences in stress-induced inflammatory responses as a potential source for the etiology of sex differences in depressive disorders. Moreover, the anti-inflammatory capacity of traditional and nontraditional antidepressants is reviewed to inform on potential pharmacotherapeutic strategies to personalize antidepressant therapy in a sex-dependent manner.

Childhood trauma and type D personality: The endocrine and cardiovascular effects on stress reactivity

Both exaggerated and blunted cardiovascular stress reactions are associated with health problems. Moreover, early life experiences and personality traits affect stress responses. Regarding the childhood traumas and type D personality, this study aimed to compare the endocrine and cardiovascular reactions against acute laboratory stress. Results showed that the simultaneous existence of childhood traumatic experiences and type D personality leads to exaggerated stress reactivity, while each factor results in a blunted cardiovascular response. Although the cardiovascular responses are dampened in type D personality people, their endocrine reactions are exaggerated. The underlying mechanisms of blunted cardiovascular reactivity differ between childhood trauma and type D personality groups.

Sex Differences in Interleukin-6 Responses Over Time Following Laboratory Pain Testing Among Patients With Knee Osteoarthritis

Epidemiological studies suggest that women are not only at a higher risk for developing knee osteoarthritis (KOA), but also report greater symptom severity compared to men. One potential underlying mechanism of these sex differences may be exaggerated inflammatory responses to pain among women compared to men. The present study examined sex differences in interleukin-6 (IL-6) response over time following experimental pain testing. We hypothesized that women, when compared to men, would show greater IL-6 reactivity when exposed to acute pain in a human laboratory setting. Eighty-four participants (36 men and 48 women) with KOA scheduled for total knee arthroplasty underwent a quantitative sensory testing (QST) battery. A total of seven IL-6 measurements were taken, twice at baseline, once immediately after QST, and every 30 minutes up to 2 hours after QST. Consistent with our hypothesis, women, when compared to men, showed accelerated increases in IL-6 levels following laboratory-evoked pain, even after controlling for body mass index, marital status, clinical pain, evoked pain sensitivity, and situational pain catastrophizing. Given that KOA is a chronic condition, and individuals with KOA frequently experience pain, these sex differences in IL-6 reactivity may contribute to the maintenance and/or exacerbation of KOA symptoms. PERSPECTIVES: The present study demonstrates that women, when compared to men, exhibit greater IL-6 reactivity after exposure to laboratory-evoked pain. Such sex differences may explain the mechanisms underlying women's higher chronic pain risk and pain perception, as well as provide further insight in developing personalized pain interventions.

Effects of low-intensity and high-intensity cycling with diesel exhaust exposure on soluble P-selectin, E-selectin, I-CAM-1, VCAM-1 and complete blood count

BACKGROUND

Exposure to particulate matter 2.5 μm or less (PM2.5) that contains transition metals may play a role in systemic oxidative stress and inflammation. Exposure to diesel exhaust (DE) can increase adhesion molecules, which are important in the inflammatory response; however, it is unclear how exercising in DE affects adhesion molecules and how exercise intensity modulates this response.

AIM

To determine how DE exposure during exercise of varying intensities affects adhesion molecules and markers of systemic inflammation.

METHODS

Eighteen males performed 30 min cycling bouts at low intensity and high intensity (30% and 60% of power at VO2peak (peak oxygen consumption) and a control condition (rest)). Each trial was performed once breathing filtered air (FA) and once breathing DE (300 μg/m3 of PM2.5, six trials in total). Prior to, immediately post, 1 and 2 hours post exposure, blood was drawn to measure parameters of a complete blood count and soluble (s) platelet-Selectin, endothelin-Selectin, intracellular cell adhesion molecule (sICAM)-1 and vascular cell adhesion molecule (sVCAM)-1. Data were analysed using repeated-measures analysis of variance.

RESULTS

Two hours following high-intensity exercise, sICAM-1 was significantly less in DE compared with FA (p=0.008). Immediately following rest (p=0.013) and high-intensity exercise (p=0.042) in DE, sICAM-1 was significantly greater than immediately following low-intensity exercise in DE. There were no significant differences in other markers between DE and FA.

CONCLUSIONS

Based on this study, healthy individuals may not experience an acute increase in adhesion molecules and systemic inflammatory markers from exercising in DE compared with FA, and higher exercise intensities do not appear to increase the likelihood that DE will affect adhesion molecules and systemic inflammatory markers.

Young Women With Coronary Artery Disease Exhibit Higher Concentrations of Interleukin-6 at Baseline and in Response to Mental Stress

Background

Young women with coronary artery disease (CAD), a group with high psychosocial burden, were previously shown to have higher levels of interleukin‐6 (IL‐6) compared with men of similar age. We sought to examine IL‐6 response to acute stress in CAD patients across sex and age, and contrast results to healthy controls and other biomarkers known to increase with mental stress (monocyte chemoattractant protein‐1 and matrix metallopeptidase‐9) and known limited stress‐reactivity (high‐sensitivity C‐reactive protein).

Methods and Results

Inflammatory biomarkers were measured at rest and 90 minutes after mental stress (speech task) among 819 patients with CAD and 89 healthy controls. Repeated‐measures models were used to investigate age (continuous) and sex differences across time, before and after adjusting for demographics, CAD risk factors, depressive symptoms, medication use, and CAD severity. Among patients with CAD, the mean age was 60 years (range, 25–79) and 31% were women. Younger women with CAD had significantly higher concentrations of IL‐6 at rest, 90 minutes after mental stress, as well as a higher response to stress, compared with similarly aged men (P<0.05 for sex by age interactions). In contrast, IL‐6 increased with age, and there were no sex differences in IL‐6 levels or response to stress among controls. Inflammatory responses to stress for high‐sensitivity C‐reactive protein, monocyte chemoattractant protein‐1, and matrix metallopeptidase‐9 among CAD patients were similar in women and men.

Conclusions

IL‐6 response to mental stress are higher in young women with CAD than men of similar age.

Stress-induced disturbances along the gut microbiota-immune-brain axis and implications for mental health: Does sex matter?

Women are roughly twice as likely as men to suffer from stress-related disorders, especially major depression and generalized anxiety. Accumulating evidence suggest that microbes inhabiting the gastrointestinal tract (the gut microbiota) interact with the host brain and may play a key role in the pathogenesis of mental illnesses. Here, the possibility that sexually dimorphic alterations along the gut microbiota-immune-brain axis could play a role in promoting this female bias of mood and anxiety disorders will be discussed. This review will also analyze the idea that gut microbes and sex hormones influence each other, and that this reciprocal crosstalk may come to modulate inflammatory players along the gut microbiota-immune-brain axis and influence behavior in a sex-dependent way.

Association between neutrophil to lymphocyte ratio and depressive symptoms among Chinese adults: A population study from the TCLSIH cohort study

BACKGROUND

The prevalence of depression in the general population has risen sharply over the past few decades and has become a major health problem throughout the world. Increasing evidence suggests that inflammation plays an important role in the pathogenesis of depression. To better understand the role of inflammation in the pathogenesis of depression we can use the neutrophil-to-lymphocyte ratio (NLR) because it is a simple and effective marker of inflammation and immunity.

METHODS

This cross-sectional study was conducted among adults from the healthy general population in Tianjin, China. NLR was measured according to the complete blood count. Depressive symptoms were assessed using the Zung Self-Rating Depression Scale (SDS), and a cutoff score of 45 was used to indicate the presence of depressive symptoms in the study participants. The relationship between NLR and the prevalence of depressive symptoms was evaluated separately for men and women using the multiple logistic regression analysis.

RESULTS

In the present study, the overall prevalence of depressive symptoms was 17.0% among all participants. In women, the multivariable-adjusted OR of having depressive symptoms was 1.28 (95% CI 1.10, 1.49; p for trend <0.01) for the fifth compared with the first quintile of NLR, and was 1.22 (95% CI 1.07,1.39; p < 0.01) per unit increase of NLR. However, no significant association was found between NLR and depressive symptoms in men.

CONCLUSION

This study suggests that increased NLR levels are independently related to depressive symptoms in women, but not in men. Further research is required to investigate this relationship with longitudinal data to establish the temporal ordering between these variables.

Neighborhood poverty and hemodynamic, neuroendocrine, and immune response to acute stress among patients with coronary artery disease

Living in neighborhoods characterized by poverty may act as a chronic stressor that results in physiological dysregulation of the sympathetic nervous system. No previous study has assessed neighborhood poverty with hemodynamic, neuroendocrine, and immune reactivity to stress. We used data from 632 patients with coronary artery disease. Patients' residential addresses were geocoded and merged with poverty data from the 2010 American Community Survey at the census-tract level. A z-transformation was calculated to classify census tracts (neighborhoods) as either having 'high' or 'low' poverty. Systolic blood pressure, diastolic blood pressure, heart rate, rate-pressure product, epinephrine, interleukin-6, and high-sensitivity C-reactive protein were measured before and after a public speaking stress task. Multilevel models were used for repeated measures and accounting for individuals nested within census tracts. Adjusted models included demographics, lifestyle and medical risk factors, and medication use. Another set of models included propensity scores weighted by the inverse probability of neighborhood status for sex, age, race, and individual-level income. The mean age was 63 years and 173 were women. After adjusting for potential confounders, participants living in high (vs. low) poverty neighborhoods had similar hemodynamic values at rest and lower values during mental stress for systolic blood pressure (157 mmHg vs. 161 mmHg; p = 0.07), heart rate (75 beats/min vs. 78 beats/min; p = 0.02) and rate-pressure product (11839 mmHg x beat/min vs 12579 mmHg x beat/min; p = 0.01). P-values for neighborhood poverty-by-time interactions were <0.05. Results were similar in the propensity weighted models. There were no significant differences in inflammatory and epinephrine responses to mental stress based on neighborhood poverty status. A blunted hemodynamic response to mental stress was observed among participants living in high poverty neighborhoods. Future studies should explore whether neighborhood poverty and blunted hemodynamic response to stress translate into differences in long-term cardiovascular outcomes.

Sex differences in interleukin-6 stress responses in people with Type 2 diabetes

People with Type 2 diabetes (T2D) show dysregulated inflammatory responses to acute stress, but the effect of sex on inflammatory responses in T2D remains unclear. The purpose of this study was to investigate differences in interleukin (IL)-6 stress responses between older men and women with T2D. One hundred and twenty-one people (76 men; mean age = 64.09, SD = 7.35, 45 women; mean age = 63.20, SD = 6.70) with doctor-verified T2D took part in this laboratory-based stress testing study. Participants carried out acute mental stress tasks, and blood was sampled at baseline, immediately poststress, 45 min poststress, and 75 min poststress to detect plasma IL-6 concentrations. IL-6 change scores were computed as the difference between the baseline measurement and the three time points poststress. Main effects and interactions were tested using mixed model analysis of covariance. We found a significant main effect of time on IL-6 levels, and a significant Sex × Time interaction. In adjusted analyses including the three change scores and all the covariates, the significant Sex × Time interaction was maintained; IL-6 responses were greater in women at 45 and 75 min poststress compared with men, adjusting for age, body mass index, smoking, household income, glycated hemoglobin, oral antidiabetic medication, insulin/other injectable antidiabetic medication, depressive symptoms, and time of day of testing. Different inflammatory stress response pathways are present in men and women with T2D, with women producing larger IL-6 increases. The long-term implications of these differences need to be elucidated in future studies.

Perceived discrimination is associated with the inflammatory response to acute laboratory stress in women at risk for cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of death in the United States and exacts a disproportionate toll on minorities. Growing evidence demonstrates that perceived discrimination is a significant contributing factor to psychological distress, chronic low-grade inflammation, and cardiovascular health. However, little is known regarding the extent to which perceived discrimination contributes to the inflammatory response to acute stress. Therefore, the purpose of this study was to examine the influence of perceived discrimination on the inflammatory response to a laboratory acute stress paradigm in women at risk for CVD. A cross-sectional sample of 99 postmenopausal women (50 African American and 49 non-Hispanic White) (mean age 60.2 years) with at least two risk factors for CVD underwent the Trier Social Stress Test (TSST). Subjects completed the Detroit Area Study Discrimination Scale (DAS-DS) Everyday Discrimination subscale and provided blood and saliva samples prior to the TSST and every 15 min up to 90 min post-TSST to measure a pro-inflammatory cytokine, interleukin-6 (IL-6). Perceived discrimination was significantly associated with the salivary IL-6 response to the TSST (b = 0.49, SE = 0.13, p = <0.001) controlling for age, race, marital status, household income, BMI, statin use, childhood maltreatment, depressive symptoms, and subjective social status. Women who reported higher levels of perceived discrimination had higher levels of salivary IL-6 at baseline and following the TSST as compared to women who reported lower levels of perceived discrimination. Results suggest that higher levels of perceived discrimination, regardless of race and socioeconomic status, may heighten levels of inflammation, prior to and following an acute stress exposure. The circulating Il-6 response was associated with BMI only and did not correlate with salivary IL-6. These data suggest that perceived discrimination may contribute to the salivary-IL-6 acute stress response. However, more research is needed to help clarify the complex relationships among stress and salivary proinflammatory cytokines.

[Effects of childhood trauma on the biochemical correlates of stress in men and women with nonpsychotic mental disorders]

AIM

To investigate gender differences in biochemical characteristics in patients with nonpsychotic mental disorders, and to study their association with childhood trauma.

MATERIAL AND METHODS

Women (n=308) and men (92) between 18 and 45 years of age, without serious somatic comorbidities, were examined. Laboratory evaluation included markers of hypothalamic-pituitary-adrenal axis activity (cortisol), hypothalamic-pituitary-thyroid system (TSH), proinflammatory cytokines (Il-1β and Il-6) and the brain derived neurotrophic factor (BDNF). All participants underwent psychometric testing, which included the Child Abuse and Trauma Scale (CATS), Beck and Hamilton depression scale (HAM-D) and Spielberger Anxiety Inventory (STAI). Correlations were studied between the biochemical parameters and total CATS scores and severity of depression and anxiety in subgroups of women and men with a depressive disorder.

RESULTS AND CONCLUSION

The men and women in the total study population significantly differed by representation of the different diagnostic classes, which was reflected by differing levels of depressive and anxiety symptoms. The main finding was a correlation between the level of childhood trauma and morning serum cortisol levels in men with depressive disorder, which was absent in women.

Within-subject associations between inflammation and features of depression: Using the flu vaccine as a mild inflammatory stimulus

BACKGROUND

Inflammation plays a role in mood and behavior that may be relevant to identifying risk factors and treatment for depression and other stress-related illnesses. The purpose of this study was to examine whether fluctuations in inflammation following a mild immune stimulus were associated with changes in daily reported features of depression for up to a week in a healthy sample of young adults.

METHODS

Forty-one undergraduate students completed daily diaries of mood, feelings of social disconnection, sleep, and physical symptoms for one week before and after receiving the seasonal influenza vaccine. Circulating plasma interleukin-6 (IL-6) was measured via blood samples taken immediately before and one day after vaccination.

RESULTS

There was a significant increase in circulating IL-6 from pre- to post-intervention (p = .008), and there was significant variability in the magnitude of IL-6 change. Greater increases in IL-6 were associated with greater mood disturbance on post-vaccine days, specifically depressed mood and cognitive symptoms.

CONCLUSIONS

Minor increases in inflammation were associated with corresponding increases in features of depression, and these associations occurred in the absence of any physical symptoms. The influenza vaccine could be used to probe causal relationships with a high degree of ecological validity, even in high-risk and vulnerable populations, to better understand the role of inflammation in the pathogenesis of depression.

Erinacine A-Enriched Hericium erinaceus Mycelium Produces Antidepressant-Like Effects through Modulating BDNF/PI3K/Akt/GSK-3β Signaling in Mice

Antidepressant-like effects of ethanolic extract of Hericium erinaceus (HE) mycelium enriched in erinacine A on depressive mice challenged by repeated restraint stress (RS) were examined. HE at 100, 200 or 400 mg/kg body weight/day was orally given to mice for four weeks. After two weeks of HE administration, all mice except the control group went through with 14 days of RS protocol. Stressed mice exhibited various behavioral alterations, such as extending immobility time in the tail suspension test (TST) and forced swimming test (FST), and increasing the number of entries in open arm (POAE) and the time spent in the open arm (PTOA). Moreover, the levels of norepinephrine (NE), dopamine (DA) and serotonin (5-HT) were decreased in the stressed mice, while the levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α were increased. These changes were significantly inverted by the administration of HE, especially at the dose of 200 or 400 mg/kg body weight/day. Additionally, HE was shown to activate the BDNF/TrkB/PI3K/Akt/GSK-3β pathways and block the NF-κB signals in mice. Taken together, erinacine A-enriched HE mycelium could reverse the depressive-like behavior caused by RS and was accompanied by the modulation of monoamine neurotransmitters as well as pro-inflammatory cytokines, and regulation of BDNF pathways. Therefore, erinacine A-enriched HE mycelium could be an attractive agent for the treatment of depressive disorders.

The effects of acute psychological stress on circulating and stimulated inflammatory markers: A systematic review and meta-analysis

Inflammatory reactivity to acute laboratory stress is thought to reflect individual differences in responsivity to environmental stressors and may confer future health risk. To characterize this response, we conducted a meta-analysis of 34 studies that measured circulating inflammatory markers and 15 studies that measured stimulated production of inflammatory markers before and after exposure to laboratory challenge. Results showed significant stress-related increases in circulating interleukin (IL)-1β (d=0.66, p<0.001), IL-6 (d=0.35, p<0.001), IL-10 (d=0.69, p<0.001), and tumor necrosis factor(TNF)-α (d=0.28, p<0.001), but not IL-1ra, IL-2, interferon-γ, or C-reactive protein. There were sufficient data to assess the time course of IL-6, IL-1β, and TNF-α reactivity. IL-6 increased from baseline to measures taken 40-50, 60-75, 90, and 120min following stress, with the largest effect at 90min post-stress (d=0.70, p<0.001). IL-1β increased from baseline to 20-30, 40-50, and 60-70min following stress, with the largest effect between 40 and 50min post-stress (d=0.73, p=0.02). For TNF-α, there was a significant increase from baseline to 31-50min post stress (d=0.44, p=0.01), but not at later times. There was no difference in magnitude of IL-6 reactivity as a function of type of stress (social-evaluative versus other). For stimulated inflammatory markers, results showed stress-related increases in IL-1β when measured 20-120min post-stress (d=1.09, p<0.001), and in IL-4 and interferon-γ when measured 0-10min post stressor (d=-0.42, p<0.001 and d=0.47, p<0.001). These results extend findings from a prior meta-analysis (Steptoe et al., 2007) to show reliable increases in circulating IL-6, IL-1β, IL-10 and TNF-α and stimulated IL-1β, IL-4 and interferon-γ in response to acute stress. It is possible that these responses contribute to associations between exposure to life challenges and vulnerability to inflammatory disease.

Sex differences in the association between stressor-evoked interleukin-6 reactivity and C-reactive protein

Individuals differ consistently in the magnitude of their inflammatory responses to acute stressors, with females often showing larger responses than males. While the clinical significance of these individual differences remains unclear, it may be that greater inflammatory responses relate to increased systemic inflammation and thereby risk for chronic inflammatory disease. Here, we examined whether acute stressor-evoked interleukin (IL)-6 responses associate with resting levels of C-reactive protein (CRP), a marker of systemic inflammation, and whether this association differs by sex. Subjects were 57 healthy midlife adults (30-51years; 33% female; 68% white). Blood was drawn before and 30-min after two mental stress tasks: a multisource interference task and a Stroop color word task. Hierarchical regressions controlling for age, sex, race, and BMI tested whether stressor-evoked IL-6 responses were associated with resting CRP and whether this association differed by sex. Results indicated that sex and stressor-evoked IL-6 responses interacted to predict CRP (ΔR²=0.08, B=-1.33, β=-0.39, p=0.02). In males, larger stressor-evoked IL-6 responses associated with higher CRP, whereas in females, stressor-evoked IL-6 responses showed a non-significant negative association with CRP. These findings indicate that inflammatory responses to acute stressors associate with resting levels of CRP; however, this association differs by sex. Previous literature suggests that there are sex differences in stressor-evoked IL-6 responses, but this is the first study to show sex differences in the relationship between acute inflammatory responses and systemic inflammation. The contribution of these sex differences to inflammatory disease risk warrants further investigation.

Post-menopausal Women Exhibit Greater Interleukin-6 Responses to Mental Stress Than Older Men

BACKGROUND

Acute stress triggers innate immune responses and elevation in circulating cytokines including interleukin-6 (IL-6). The effect of sex on IL-6 responses remains unclear due to important limitations of previous studies.

PURPOSE

The purpose of this study was to examine sex differences in IL-6 responses to mental stress in a healthy, older (post-menopausal) sample accounting for several moderating factors.

METHODS

Five hundred six participants (62.9 ± 5.60 years, 55 % male) underwent 10 min of mental stress consisting of mirror tracing and Stroop task. Blood was sampled at baseline, after stress, and 45 and 75 min post-stress, and assayed using a high sensitivity kit. IL-6 reactivity was computed as the mean difference between baseline and 45 min and between baseline and 75 min post-stress. Main effects and interactions were examined using ANCOVA models.

RESULTS

There was a main effect of time for the IL-6 response (F 3,1512 = 201.57, p = <.0001) and a sex by time interaction (F 3,1512 = 17.07, p = <.001). In multivariate adjusted analyses, IL-6 reactivity was significantly greater in females at 45 min (M = 0.37 ± 0.04 vs. 0.20 ± 0.03 pg/mL, p = .01) and at 75 min (M = 0.57 ± 0.05 vs. 0.31 ± 0.05 pg/mL, p = .004) post-stress compared to males. Results were independent of age, adiposity, socioeconomic position, depression, smoking and alcohol consumption, physical activity, statin use, testing time, task appraisals, hormone replacement, and baseline IL-6. Other significant predictors of IL-6 reactivity were lower household wealth, afternoon testing, and baseline IL-6.

CONCLUSIONS

Healthy, post-menopausal females exhibit substantially greater IL-6 responses to acute stress. Inflammatory responses if sustained over time may have clinical implications for the development and maintenance of inflammatory-related conditions prevalent in older women.

Young women post-MI have higher plasma concentrations of interleukin-6 before and after stress testing

OBJECTIVES

Young women have poorer prognosis after myocardial infarction (MI) and a higher rate of mental stress-induced ischemia compared with similarly aged men. A higher inflammatory status may help explain these sex differences.

METHODS

We examined 98 patients (49 women and 49 men) age 18-59years with recent MI (past 6months). Women and men were matched for age, type of MI, and time since MI. Interleukin 6 (IL-6) concentrations were measured at baseline, after mental stress using a speech task, and after exercise/pharmacologic stress (60 and 90min). Depressive symptoms were measured with the Beck Depression Inventory (BDI-II) and angiographic coronary artery disease (CAD) severity was quantified with the Gensini score. Single-photon emission computed tomography (SPECT) was used to obtain a computerized measurement of stress-induced ischemia (summed difference score, or SDS) and determine whether severity of stress-induced ischemia affects the inflammatory response to stress. Analysis was stratified by the median age of 50. Geometric mean concentrations of IL-6 were obtained from general linear regression models.

RESULTS

In both age groups, women had less angiographic CAD and a similar level of conventional risk factors compared with men. Despite this, baseline IL-6 geometric means before both mental and physical stress were twice as high in women ⩽50years of age compared to age-matched men (3.8 vs. 1.8pg/mL, p=0.001, across both conditions), while they were similar in women and men age >50years (2.3 vs. 2.2pg/mL, p=0.83). After mental stress, IL-6 concentrations increased in both women and men in a similar fashion and remained twice as high in women ⩽50years than men at both 60min (5.4 vs. 2.6pg/mL, p=0.002) and 90min (5.9 vs. 3.4pg/mL, p=0.01). No significant difference was found between women and men >50years of age at any time point after mental stress. Results were similar for physical stress. After accounting for SDS, IL-6 concentrations in young women remained higher after both mental and physical stress. Baseline IL-6 concentrations were not significantly related to inducible ischemia.

CONCLUSIONS

After MI, young women aged 50years or younger, compared with age-matched men, have remarkably higher concentrations of inflammation at baseline and after both mental and physical stress, with a similar inflammatory response to both stressors. Sustained concentrations of inflammation in young women, not their response to stress, may contribute to their adverse outcomes post-MI.

Unhealthy lifestyle may increase later depression via inflammation in older women but not men

Depression and inflammatory markers have a reliable cross-sectional association although less is known about the prospective relationship. The current study investigated whether pro-inflammatory markers are prospectively associated with depression, and whether indicators of unhealthy lifestyle, physical health and psychosocial functioning may drive this association. Participants were drawn from the Hunter Community Study, a community-dwelling cohort of individuals aged 55-85 years (N = 1410). Participants completed baseline physiological assessment, health-related questionnaires, and blood sampling for the analysis of inflammatory markers, C-reactive protein (CRP) and interleukin (IL)-6. Participants completed the same depressive symptom questionnaire again after 3.5-5.5 years. Depression outcomes at follow-up were analysed dichotomously using established scale cut-off scores and continuously as a "residual score", representing the variation in follow-up depressive symptoms not explained by baseline symptoms and age. Analyses were conducted on males and females separately. At baseline, indicators of unhealthy lifestyle, physical health and psychosocial functioning were associated with depressive symptoms and inflammatory markers. For males, there were no relationships between inflammatory markers and follow-up depression outcomes. In females, IL-6 was significantly associated with depression outcomes in univariate, but not multivariate analyses. However, IL-6 significantly mediated the association between the predictors of waist-to-hip ratio, smoking and psychological coping at baseline, and follow-up depression outcomes. The results support the inflammatory hypothesis of depression, although females may be more vulnerable to effects. The findings raise the possibility that unhealthy lifestyle and psychosocial stress may drive inflammation and subsequent depressive symptoms.

Modification of hippocampal markers of synaptic plasticity by memantine in animal models of acute and repeated restraint stress: implications for memory and behavior

Stress is any condition that impairs the balance of the organism physiologically or psychologically. The response to stress involves several neurohormonal consequences. Glutamate is the primary excitatory neurotransmitter in the central nervous system, and its release is increased by stress that predisposes to excitotoxicity in the brain. Memantine is an uncompetitive N-methyl D-aspartate glutamatergic receptors antagonist and has shown beneficial effect on cognitive function especially in Alzheimer's disease. The aim of the work was to investigate memantine effect on memory and behavior in animal models of acute and repeated restraint stress with the evaluation of serum markers of stress and the expression of hippocampal markers of synaptic plasticity. Forty-two male rats were divided into seven groups (six rats/group): control, acute restraint stress, acute restraint stress with Memantine, repeated restraint stress, repeated restraint stress with Memantine and Memantine groups (two subgroups as positive control). Spatial working memory and behavior were assessed by performance in Y-maze. We evaluated serum cortisol, tumor necrotic factor, interleukin-6 and hippocampal expression of brain-derived neurotrophic factor, synaptophysin and calcium-/calmodulin-dependent protein kinase II. Our results revealed that Memantine improved spatial working memory in repeated stress, decreased serum level of stress markers and modified the hippocampal synaptic plasticity markers in both patterns of stress exposure; in ARS, Memantine upregulated the expression of synaptophysin and brain-derived neurotrophic factor and downregulated the expression of calcium-/calmodulin-dependent protein kinase II, and in repeated restraint stress, it upregulated the expression of synaptophysin and downregulated calcium-/calmodulin-dependent protein kinase II expression.

Salivary markers of inflammation in response to acute stress

There is burgeoning interest in the ability to detect inflammatory markers in response to stress within naturally occurring social contexts and/or across multiple time points per day within individuals. Salivary collection is a less invasive process than current methods of blood collection and enables intensive naturalistic methodologies, such as those involving extensive repeated measures per day over time. Yet the reliability and validity of saliva-based to blood-based inflammatory biomarkers in response to stress remains unclear. We review and synthesize the published studies that have examined salivary markers of inflammation following exposure to an acute laboratory stressor. Results from each study are reviewed by analyte (IL-1β, TNF-α, IL-6, IL-2, IL-4, IL-10, IL-12, CRP) and stress type (social-cognitive and exercise-physical), after which methodological issues and limitations are addressed. Although the literature is limited, several inflammatory markers (including IL-1β, TNF-α, and IL-6) have been reliably determined from saliva and have increased significantly in response to stress across multiple studies, with effect sizes ranging from very small to very large. Although CRP from saliva has been associated with CRP in circulating blood more consistently than other biomarkers have been associated with their counterparts in blood, evidence demonstrating it reliably responds to acute stress is absent. Although the current literature is presently too limited to allow broad assertion that inflammatory biomarkers determined from saliva are valuable for examining acute stress responses, this review suggests that specific targets may be valid and highlights specific areas of need for future research.

Cytokine variations and mood disorders: influence of social stressors and social support

Stressful events have been implicated in the evolution of mood disorders. In addition to brain neurotransmitters and growth factors, the view has been offered that these disorders might be provoked by the activation of the inflammatory immune system as well as by de novo changes of inflammatory cytokines within the brain. The present review describes the impact of social stressors in animals and in humans on behavioral changes reminiscent of depressive states as well as on cytokine functioning. Social stressors increase pro-inflammatory cytokines in circulation as well as in brain regions that have been associated with depression, varying with the animal's social status and/or behavioral methods used to contend with social challenges. Likewise, in humans, social stressors that favor the development of depression are accompanied by elevated circulating cytokine levels and conversely, conditions that limit the cytokine elevations correlated with symptom attenuation or reversal. The implications of these findings are discussed in relation to the potentially powerful effects of social support, social identity, and connectedness in maintaining well-being and in diminishing symptoms of depression.

Fatigability disrupts cognitive processes' regulation of inflammatory reactivity in old age

OBJECTIVE

High fatigability, a dysfunctional adaption to fatigue, may lead to difficulties performing otherwise regularly encountered cognitive activities and may be related to pro-inflammatory reactivity. The purpose of the study was to investigate the effect of fatigability on cognitive processes and inflammatory response after an acute cognitive stress task in older adults.

METHODS

In an observational stress reactivity study conducted in a light- and temperature-controlled laboratory, we measured IL-6, self-reported acute fatigue, and frontally oriented cognitive processes in 55 community-dwelling individuals aged 75 years or older as part of a demanding set of cognitive tasks intended to induce stress.

RESULTS

Subjects were classified into groups of low and high fatigability based on cluster analysis of their self-report acute fatigue before and after the cognitive tasks. The two clusters were comparable on levels of baseline IL-6 and cognitive processes; however, the high fatigability cluster had significantly higher levels of IL-6 response than the low fatigability cluster. After controlling for multiple covariates, fatigability moderated the relationship between speed of processing and IL-6 reactivity. Further exploratory analyses indicated significant adverse associations between speed of processing and attention and IL-6 reactivity in the group with low but not high fatigability.

CONCLUSION

Although observational, these data are consistent with the notion that pro-inflammatory states in older adults might be reduced by improvements in cognitive processes. Because fatigability was associated with increased acute inflammatory response and disrupted the normal stress regulation provided by the cognitive processes, future randomized studies might examine whether fatigability alleviation reduces IL-6.

Underlying inflammation has no impact on the oxidative stress response to acute mental stress

INTRODUCTION

Mental stress is considered to be a trigger for acute myocardial infarction (MI), with inflammation thought to provide a mechanism. Inflammation is reciprocally linked to oxidative stress, which has also been implicated in MI. The purpose of this study was to assess the effects of experimentally-induced inflammation on the oxidative stress response to mental stress in healthy participants.

METHODS

Healthy males undertook one of two inflammatory stimuli: typhoid vaccination (Vaccination paradigm, N=17) or eccentric exercise (Eccentric exercise paradigm, N=17). All participants completed a mental arithmetic stress task twice (within-subject design): 6h after the inflammatory stimulus, and during a control non-inflammation condition. Blood samples were taken before, immediately and 30min after the stress task. Plasma was assessed for interleukin-6 (IL-6), protein carbonyls (PC), lipid hydroperoxides (LOOH), total antioxidant capacity (TAC) and nitric oxide metabolites (NOx).

RESULTS

Vaccination paradigm: IL-6, PC and NOx were significantly higher in the vaccination condition, relative to the control condition (p<.05). PC, TAC, LOOH and NOx were unchanged in response to mental stress in both the vaccination and control conditions. Eccentric Exercise paradigm: IL-6 and TAC were significantly higher in the eccentric exercise condition (p<.05), relative to the control condition. PC, TAC and NOx were unchanged in response to mental stress in both the eccentric exercise and control conditions.

CONCLUSIONS

Two different inflammatory paradigms were successful in increasing selective plasma markers of inflammation and oxidative stress prior to a mental stress task. However, experimentally induced transient inflammation had no impact on mental stress-induced changes in plasma LOOH, PC, TAC or NOx in young healthy participants.

Limitation of pro- and anti-inflammatory cytokine analysis to discriminate biological stress effects in patients suffering from chronic psychological distress

BACKGROUND

Research endeavors aiming to evaluate the effect of prolonged psychological distress on the immune system have been pursed over the past decades. Due to the complexity of the two systems involved, the mental and immune status, a large number of questions still remains to be addressed.

AIM

In the present study, we aimed to test if chronic distress is associated with pro- and anti-inflammatory cytokine levels in a well-defined study cohort.

METHODS

We recruited 42 inpatients suffering from post-traumatic embitterment disorder (PTED), a condition that has been demonstrated to cause intense and persistent psychological distress. Study participants completed established questionnaires to evaluate stress perception, depression and quality of life before and after psychotherapy, aiming to improve stress coping. Venous blood samples to detect serum levels of pro- and anti-inflammatory cytokines [interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ] were obtained pre- and post-treatment.

RESULTS

The psychological assessments showed an increase of quality of life, a decrease of perceived stress and depressive symptoms, between the two groups. These findings are not associated with significant alterations of the cytokine levels before and after treatment.

CONCLUSIONS

In our study, the psychological treatment of inpatients suffering from chronic psychological distress does not result in changes in cytokine levels. Further research with a broader analysis of immune markers and enhanced detection methods may be required to unveil psycho-immunological association in PTED patients.

Long lasting effects of smoking: breast cancer survivors' inflammatory responses to acute stress differ by smoking history

Cigarette smoking continues to be the most preventable cause of illness and death and has been linked to the development and prognosis of cancer. Current smokers have higher levels of inflammation than nonsmokers, and inflammation can remain elevated in former smokers even years following cessation. Inflammation can also be enhanced by stress. This study examined cortisol and inflammatory responses to a laboratory stressor in breast cancer survivors who formerly smoked compared to their counterparts who had never smoked. Participants included 89 women (age=51.6±8.9 years) who had completed treatment for stage 0-IIIA breast cancer within the past three years and were at least two months post surgery, radiation or chemotherapy, whichever occurred last. Cortisol and interleukin-6 (IL-6) were evaluated in response to a standardized laboratory speech and mental arithmetic stressor. Former (n=25) and never (n=64) smokers did not differ by cancer stage, cancer treatment, comorbidities, time since cancer treatment, depression, or stress. Despite having similar cortisol responses to the stressor, former smokers had exaggerated IL-6 responses two hours post-stressor compared to never smokers. This effect persisted after controlling for age, BMI, time since treatment, education, and antidepressant use. An exaggerated and prolonged inflammatory response to stress could be one mechanism underlying the persistent inflammation observed in former smokers.

The adaptive neuroplasticity hypothesis of behavioral maintenance

Physical activity is a seemingly simple and clinically potent method to decrease morbidity and mortality in people with coronary heart disease (CHD). Nonetheless, long-term maintenance of physical activity remains a frustratingly elusive goal for patients and practitioners alike. In this paper, we posit that among older adults with CHD, recidivism after the initiation of physical activity reflects maladaptive neuroplasticity of malleable neural networks, and people will revert back to learned and habitual physical inactivity patterns, particularly in the setting of stress or depression. We hypothesize that behavioral interventions that successfully promote physical activity may also enhance adaptive neuroplasticity and play a key role in the maintenance of physical activity through the development of new neuronal pathways that enhance functional ability in older adults. Conversely, without such adaptive neuroplastic changes, ingrained maladaptive neuroplasticity will prevail and long-term maintenance of physical activity will fail. In this paper we will: (1) describe the enormous potential for neuroplasticity in older adults; (2) review stress and depression as examples of maladaptive neuroplasticity; (3) describe an example of adaptive neuroplasticity achieved with a behavioral intervention that induced positive affect in people with CHD; and (4) discuss implications for future work in bench to bedside translational research.

Circulating cytokine signatures in healthy medical students exposed to academic examination stress

Stress-induced production of proinflammatory cytokines in the brain and periphery is associated with mental distress. In this study, we measured changes in levels of salivary cortisol and 50 circulating immune mediators in 28 4th-grade medical students (19 males and 9 females) 7 weeks before, 1 day before, immediately after, and 1 week after an authorized nationwide examination for promotion. Repeated measures ANOVA with multiple testing correction and post hoc tests revealed that the examination significantly increased levels of proinflammatory cytokines (granulocyte colony-stimulating factor, interferon-γ, interleukin (IL)-1β, and tumor necrosis factor-α), Th2 cytokines (IL-4, IL-5, and IL-13), and β-nerve growth factor in association with significant decreases in salivary cortisol levels and anxiety after the examination. These mediators may have a negative impact on the mental state of healthy young adults exposed to naturalistic stressors.

Hormones, heart disease, and health: individualized medicine versus throwing the baby out with the bathwater

It is increasingly axiomatic that depression has widespread adverse physiological effects and, conversely, that a variety of physiological systems impact the risk for developing depression. This convergence of depression and altered physiology is particularly dramatic during midlife--a time during which reproductive failure presages dramatic increases in prevalence of both heart disease and depression. The potentially meaningful and illuminating links between estrogen deficiency, cardiovascular disease (CVD), and depression have largely been obscured, first by assertions, subsequently repudiated, that the perimenopause was not a time of increased risk of depression, and more recently by the denegration of hormone replacement therapy by initial reports of the Women's Health Initiative. Increasingly, however, research has led to unavoidable conclusions that CVD and depression share common, mediating pathogenic processes and that these same processes are dramatically altered by the presence or absence of estrogen (E2). This review summarizes data supporting these contentions with the intent of placing depression and estrogen therapy in their proper physiologic context.

Hormones, heart disease, and health: individualized medicine versus throwing the baby out with the bathwater

It is increasingly axiomatic that depression has widespread adverse physiological effects, and conversely that a variety of physiological systems impact the risk for developing depression. This convergence of depression and altered physiology is particularly dramatic during midlife-a time during which reproductive failure presages dramatic increases in prevalence of both heart disease and depression. The potentially meaningful and illuminating links between estrogen (E2) deficiency, cardiovascular disease (CVD), and depression have largely been obscured, first by assertions, subsequently repudiated that the perimenopause was not a time of increased risk of depression, and more recently by the denegration of hormone replacement therapy by initial reports of the Women's Health Initiative. Increasingly, however, research has led to unavoidable conclusions that CVD and depression share common and mediating pathogenic processes and that these same processes are dramatically altered by the presence or absence of E2. This review summarizes data supporting this contention with the intent of placing depression and E2 therapy in their proper physiologic context.

Exposure to a social stressor alters the structure of the intestinal microbiota: implications for stressor-induced immunomodulation

The bodies of most animals are populated by highly complex and genetically diverse communities of microorganisms. The majority of these microbes reside within the intestines in largely stable but dynamically interactive climax communities that positively interact with their host. Studies from this laboratory have shown that stressor exposure impacts the stability of the microbiota and leads to bacterial translocation. The biological importance of these alterations, however, is not well understood. To determine whether the microbiome contributes to stressor-induced immunoenhancement, mice were exposed to a social stressor called social disruption (SDR), that increases circulating cytokines and primes the innate immune system for enhanced reactivity. Bacterial populations in the cecum were characterized using bacterial tag-encoded FLX amplicon pyrosequencing. Stressor exposure significantly changed the community structure of the microbiota, particularly when the microbiota were assessed immediately after stressor exposure. Most notably, stressor exposure decreased the relative abundance of bacteria in the genus Bacteroides, while increasing the relative abundance of bacteria in the genus Clostridium. The stressor also increased circulating levels of IL-6 and MCP-1, which were significantly correlated with stressor-induced changes to three bacterial genera (i.e., Coprococcus, Pseudobutyrivibrio, and Dorea). In follow up experiments, mice were treated with an antibiotic cocktail to determine whether reducing the microbiota would abrogate the stressor-induced increases in circulating cytokines. Exposure to SDR failed to increase IL-6 and MCP-1 in the antibiotic treated mice. These data show that exposure to SDR significantly affects bacterial populations in the intestines, and remarkably also suggest that the microbiota are necessary for stressor-induced increases in circulating cytokines.

Job satisfaction is associated with elevated natural killer cell immunity among healthy white-collar employees

Although the association of job satisfaction with health has been well documented, little is known about the biological mechanisms underlying this relationship. This study investigates the association of job satisfaction with cell-mediated immunity among Japanese white-collar daytime workers. A total of 306 healthy full-time employees (141 women and 165 men), aged 22-69 (mean 36) years, provided a blood sample for the measurement of circulating immune (natural killer (NK), B, and total T) cells and NK cell cytotoxicity (NKCC) and completed a questionnaire survey during April to June 2002. Job satisfaction was measured by a 4-item scale from the Japanese version of the generic job stress questionnaire with higher scores indicating greater satisfaction. Analyses were done separately for women and men using a hierarchical multiple linear regression model controlling for multiple confounders. The results revealed that greater job satisfaction was positively correlated with NKCC (β = .207; p = .029) and the number of NK (CD3(-)CD56(+)) cells (β = .261; p = .008) in women. In men, job satisfaction was marginally correlated with NKCC (β = .165; p = .050) but was not correlated with the number of NK (CD3(-)CD56(+)) cells (β = .142; p = .107). Job satisfaction did not correlate with numbers of T (CD3(+)CD56(-)) and B (CD19(+)) cells in both women and men. Our findings suggest an independent association between job satisfaction and NK cells but the association seems to be stronger in women than in men. Although the results provide a support for the biological plausibility of the job satisfaction-health relationship, additional research is required to determine whether greater job satisfaction contributes to recovery/maintenance of NK cell immunity and host defense over time.

Associations of depressive symptoms, trait hostility, and gender with C-reactive protein and interleukin-6 response after emotion recall

OBJECTIVE

To examine the effects of depressive symptoms and hostility on changes in C-reactive protein (CRP) and interleukin (IL)-6 in response to an acute laboratory stressor. Depressive symptoms moderate the effect of trait hostility on circulating levels of CRP and IL-6.

METHODS

The study included 307 men and 218 women, affording the opportunity to examine moderation by gender. Regression analyses were performed to examine depressive symptoms, hostility ratings, gender, and their interactions as predictors of CRP and IL-6 response to an emotion recall task. Analyses were adjusted for age, race, body mass index, and prerecall task levels of either CRP or IL-6.

RESULTS

The product term for Depressive Symptoms x Hostility x Gender was not significantly related to CRP nor IL-6 response. However, Depressive Symptoms x Hostility did interact to predict CRP response (p = .002); those with the combination of high symptoms of depression and hostility had the largest CRP response. The Depressive Symptoms x Gender interaction was also a predictor of both CRP (p = .001) and IL-6 (p = .04) response; for each inflammatory marker, depressive symptoms were significantly associated with higher CRP response in women, as compared with men. Hostility did not moderate depressive symptoms, nor gender for IL-6.

CONCLUSIONS

Our findings extend prior research by suggesting that, broadly speaking, depression is related to inflammatory markers; however, this relationship seems complex. Depression seems to be related to inflammation more strongly among hostile individuals and more strongly among women than among men.

Low vagal tone is associated with impaired post stress recovery of cardiovascular, endocrine, and immune markers

Reduced heart rate variability (HRV) and delayed blood pressure recovery are associated with increased cardiovascular risk. Besides this evident link, the vagus is thought to play an inhibitory role in the regulation of other allostatic systems, including inflammation and the hypothalamic-pituitary-adrenal (HPA) axis. However, human evidence is scarce. To further explore these associations and with special regard to the postulated mediating role of the vagus, we hypothesised that subjects with low vagal tone as indexed by reduced resting HRV would show impaired post-stress recovery of cardiovascular, endocrine and immune system markers involved in cardiovascular pathology. 44 healthy men underwent a standardised mental stress test. Besides continuous measurement of systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), and HRV serum cortisol, tumour necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) were measured before, after, 20, and 60 min after stress. Low versus high HRV groups was defined by median split on resting HRV (RMSSD). The task elicited significant time effects for SBP, DBP, HR, HRV, cortisol, and TNF-alpha. Subjects with low baseline HRV showed almost no modulation of HRV coupled with overall reduced HRV levels, and impaired recovery of DBP, cortisol, and TNF-alpha. Confirming our hypothesis, low vagal tone was associated with impaired recovery of cardiovascular, endocrine, and immune markers in healthy males. The data support an inhibitory role of the vagus in the regulation of allostatic systems as described in the neurovisceral integration model. We posit reduced resting HRV as a risk marker for future cardiovascular and other stress-related disease.

Pyrogenic cytokines did not mediate a stress interview-induced hyperthermic response in a patient with psychogenic fever: a case report

OBJECTIVE

To investigate if pyrogenic cytokines mediated psychological stress-induced hyperthermic response in a patient with psychogenic fever. Despite many case reports on psychogenic fever, the mechanism responsible for how psychological stress increases core body temperature (Tc) in humans is not yet known.

CASE PRESENTATION

A 13-year-old girl with fever (>38 degrees C) of unknown causes was referred to our department because psychogenic fever was suspected. To determine if the fever was actually induced by psychological stress, we conducted a 60-minute stress interview. Her baseline oral temperature was 36.60 degrees C and it began to increase immediately after commencement of the interview, reaching a maximum of 37.42 degrees C 20 minutes after the end of the interview. The plasma level of prostaglandin E(2) and the serum interleukin-6 level were increased 90 minutes after the interview. Serum levels of interleukin-1alpha, interleukin-1beta, and macrophage inflammatory protein-1alpha were all less than their minimum detectable level throughout the observation period. We also measured the patient's thermal preference by immersing her hands in warm (40 degrees C) and cold (20 degrees C) water. Her preference changed from cold to warm only during the increasing phase of oral temperature.

CONCLUSIONS

This case report shows that a stress interview actually increased Tc in a patient with psychogenic fever. This study suggests that, although pyrogenic cytokines are not involved, the stress interview-induced increase in Tc was an active hyperthermia under the control of the brain, as is infection-induced fever.

Association of polymorphism in the human mu-opioid receptor OPRM1 gene with proinflammatory cytokine levels and health perception

Recent studies in psychoneuroimmunology have indicated that proinflammatory cytokines cause several diseases and behaviors that overlap symptomatically with depression. It is known that the endogenous opioid peptide beta-endorphin regulates proinflammatory cytokine secretion from peripheral immune cells via mu-opioid receptor-dependent mechanisms. Therefore, it is possible that the functional polymorphism of the mu-opioid receptor gene (OPRM1, SNP: A118G) influences peripheral circulating proinflammatory cytokine levels and the health-related quality of life (QOL) even in healthy populations. In this study, we compared the serum concentrations of several proinflammatory cytokines (interleukin-2 (IL-2), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma)) and the health-related QOL between OPRM1 genotypes. Interestingly, serum concentrations of IL-6, TNF-alpha, and IFN-gamma were significantly lower and the general health score was significantly higher in carriers of the G allele, who show a strong binding of beta-endorphin to the mu-opioid receptor as compared to individuals without the G allele. Correlation analysis indicated that the general health score was negatively correlated with the IL-6 serum concentration. These results suggest that the sensitive endogenous opioid system in carriers of the G allele may suppress proinflammatory cytokine secretion from peripheral immune cells; consequently, it may influence the health perception.

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

BACKGROUND

Proinflammatory cytokines have been reported to be elevated in individuals experiencing chronic stress as well as in those with major depressive disorder. Much less is known about cytokines in anxiety disorders such as posttraumatic stress disorder (PTSD) and panic disorder (PD). We hypothesized that PD and PTSD would be associated with a generalized proinflammatory cytokine signature.

METHOD

We utilized Luminex technology to examine 20 cytokines and chemokines in serum from 48 well-characterized individuals with a primary DSM-IV PD or PTSD diagnosis, and 48 age- and gender-matched healthy controls. We conservatively employed a Bonferroni correction for multiple testing (alpha=.05/20=.0025).

RESULTS

Individuals with primary PTSD or PD had significantly elevated median peripheral cytokine levels for 18 of 20 different cytokines compared to age- and gender-matched healthy controls (all P<.0025). To assess for the presence of a generalized proinflammatory state, we also examined the proportion of subjects with detectable levels of at least six of nine common proinflammatory cytokines and chemokines (IL-6, IL-1alpha, IL-1beta, IL-8, MCP-1, MIP-1alpha, Eotaxin, GM-CSF, and IFN-alpha). For men and women, 87% of anxiety patients had six or more detectable levels of these proinflammatory cytokines, compared with only 25% of controls (Fisher's Exact Test (FET) P=.000). Confirmatory analysis of the subset of individuals without current psychiatric medication use or comorbid depression was of comparable significance.

CONCLUSIONS

These findings suggest that a generalized inflammatory state may be present in individuals with PD or PTSD.

Acute deviations from long-term trait depressive symptoms predict systemic inflammatory activity

OBJECTIVE

Depressive symptoms increase morbidity and mortality from coronary heart disease and systemic inflammation has been proposed as the underlying mechanism. While higher levels of inflammatory mediators have been found in dysphoric individuals, it is not known whether long-term or short-term mood changes are responsible for this phenomenon.

METHODS

A sample of 65 young women provided weekly web-based self-ratings of depressive mood over a period of 20 weeks using the CES-D, and systemic inflammation was assessed by measuring plasma interleukin-6 (IL-6) and C-reactive protein (CRP) before and after the observation period. CES-D ratings were used to develop state and trait indicators of depressed mood and evaluate their relationship with inflammatory mediators.

RESULTS

Hierarchical linear regressions controlling for baseline inflammation, age, and BMI revealed that trait levels of depressive symptoms were not associated with IL-6 (beta=0.09; n.s.) and CRP (beta=0.01; n.s.) concentrations after the observation period. In contrast, state levels of depressive symptoms were associated with changes in IL-6, but not CRP, particularly when they were indexed as the disparity between a person's trait level of symptoms and her CES-D score just prior to IL-6 assessment (beta=0.35; p=0.03).

CONCLUSION

These results lead us to conclude that in young women, state, rather than trait depressed mood stimulates peripheral inflammation as measured by IL-6. This pattern suggests that in this age group, fast-reacting inflammatory mediators such as IL-6 probably respond to short-term changes, for example, in stress hormones or stress hormone sensitivity, rather than long-term dysregulations of allostatic mechanisms.