Stimulated production of interleukin-8 covaries with psychosocial risk factors for inflammatory disease among middle-aged community volunteers

The impact of inflammatory response on psychological status of medical staff during COVID-19 pandemic

BACKGROUND

Limited research has been conducted on the relationship between inflammatory markers and psychological status in medical staff fighting COVID-19.

OBJECTIVE

This article examines the psychological and inflammatory conditions of medical personnel working on the front lines of the battle against COVID-19.

METHODS

A total of 102 clinical staff members were included in this study. All subjects received the Symptom Checklist-90 questionnaire (SCL-90) and Posttraumatic Stress Disorder Checklist-Civilian questionnaires for assessing different mental symptoms. The levels of various inflammatory markers, including IL-1β, IL-2, IL-6, IL-8, TNF-a, and IFN-γ, along with GDNF, were evaluated.

RESULTS

Spearman correlation analysis showed that the levels of IL-6 were positively associated with the anxiety score (Spearman's rho = .230, p = .021), obsessive-compulsive symptoms (Spearman's rho = .201, p = .042). The levels of IL-8 were negatively associated with the anxiety score (Spearman's rho = -.223, p = .028), obsessive-compulsive symptoms (Spearman's rho = -.252, p = .012), hyperarousal (Spearman's rho = -.221, p = .028). The levels of TNF-α were positively associated with the anxiety score (Spearman's rho = .201, p = .045), obsessive-compulsive symptoms (Spearman's rho = .222, p = .035).

CONCLUSION

Generally, our results suggested that IL-6, IL-8 and TNF-α might play a role in the development of psychological symptoms among medical staff.

IL-8 (CXCL8) Correlations with Psychoneuroimmunological Processes and Neuropsychiatric Conditions

Interleukin-8 (IL-8/CXCL8), an essential CXC chemokine, significantly influences psychoneuroimmunological processes and affects neurological and psychiatric health. It exerts a profound effect on immune cell activation and brain function, suggesting potential roles in both neuroprotection and neuroinflammation. IL-8 production is stimulated by several factors, including reactive oxygen species (ROS) known to promote inflammation and disease progression. Additionally, CXCL8 gene polymorphisms can alter IL-8 production, leading to potential differences in disease susceptibility, progression, and severity across populations. IL-8 levels vary among neuropsychiatric conditions, demonstrating sensitivity to psychosocial stressors and disease severity. IL-8 can be detected in blood circulation, cerebrospinal fluid (CSF), and urine, making it a promising candidate for a broad-spectrum biomarker. This review highlights the need for further research on the diverse effects of IL-8 and the associated implications for personalized medicine. A thorough understanding of its complex role could lead to the development of more effective and personalized treatment strategies for neuropsychiatric conditions.

Association of markers of inflammation on attention and neurobehavioral outcomes in survivors of childhood acute lymphoblastic leukemia

Background

Survivors of childhood acute lymphoblastic leukemia (ALL) are at-risk of developing cognitive impairment and neurobehavioral symptoms. Inflammation induced by a compromised health status during cancer survivorship is proposed as a pathophysiological mechanism underlying cognitive impairment in cancer survivors.

Objectives

To evaluate the associations of biomarkers of inflammation with attention and neurobehavioral outcomes in survivors of childhood ALL, and to identify clinical factors associated with biomarkers of inflammation in this cohort.

Methods

We recruited patients who were diagnosed with ALL at ≤ 18 years old and were currently ≥5 years post-cancer diagnosis. The study outcomes were attention (Conners Continuous Performance Test) and self-reported behavioral symptoms (Adult Self-Report [ASR] checklist). Using a commercial screening kit, survivors' plasma (5ml) was assayed for 17 cytokines/chemokine cell-signaling molecules that are associated with neurodegenerative diseases. The final panel of the targeted markers included interleukin (IL)-8, IL-13, interferon-gamma (IFN-γ), monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1β, and tumor necrosis factor-α. Biomarker levels were rank-ordered into tertiles based on the sample distribution. Multivariable general linear modeling was used to test for associations between biomarkers and study outcomes in the overall cohort and stratified by gender.

Results

This study included 102 survivors (55.9% males, mean[SD] age 26.2[5.9] years; 19.3[7.1] years post-diagnosis). Survivors within top tertiles of IFN-γ (Estimate =6.74, SE=2.26; P=0.0037) and IL-13 (Estimate =5.10, SE=2.27; P=0.027) demonstrated more inattentiveness. Adjusting for age, gender and treatment, more self-reported thought (Estimate=3.53, SE=1.78; P=0.050) and internalizing problems (Estimate =6.52, SE=2.91; P=0.027) correlated with higher IL-8. Higher levels of IL-13 (RR = 4.58, 95% CI: 1.01-11.10) and TNF-α (RR = 1.44, 95% CI: 1.03-4.07) were observed in survivors had developed chronic health conditions (n=26, 25.5%). The stratified analysis showed that association of IFN-γ with attention was stronger in male survivors than in female survivors.

Conclusion

Inflammation due to cancer-related late effects may potentially be mechanistic mediators of neurobehavioral problems in pediatric ALL survivors. Markers of inflammation can potentially be applied to assess or monitor the effectiveness of interventions, particularly behavioral interventions, in improving cognitive outcomes in survivors. Future work includes understanding the underlying gender-specific pathophysiology behind functional outcomes in the population.

Genetic Variation, Stress, and Physiological Stress Response in Adults With Food Allergy or Celiac Disease

BACKGROUND

Persistently high chronic stress can lead to maladaptive psychological, behavioral, and physiological stress responses and poor mental and physical health, highlighting the importance of identifying individuals at increased risk. Chronic health condition diagnosis and genetics are 2 characteristics that can influence stress, stress response, and health outcomes.

PURPOSE

Food allergy (FA) and celiac disease (CD) require constant vigilance in daily life and can lead to increased stress. The purpose of this exploratory analysis was to examine the association of variants in selected stress-related genes with stress exposures, stress, clinical measures of physiological stress response, and mental health symptoms in adults with and without FA or CD.

METHODS

We compared stress exposures, symptoms of PTSD, depression, anxiety, and stress, BMI, and waist-hip ratio between cases and controls. We analyzed the association of SNPs in genes with known or hypothesized associations with stress-related measures in 124 cases and 124 matched controls: CRHBP (rs7718461, rs10474485), CRHR1 (rs242940) and OXTR (rs2268490). For this exploratory study, p-values ≤ 0.10 were considered suggestive.

RESULTS

For cases and controls, rs7718461 was associated with stress symptoms, rs2268490 with symptoms of stress and PTSD, and rs242940 with symptoms of stress, PTSD, anxiety, and depression. Further analyses found that stress-related outcomes in individuals with FA or CD may be influenced by SNP genotype.

CONCLUSIONS

Given these suggestive findings, larger prospective studies should examine similar relationships in individuals with other chronic health conditions, incorporating factors such as environmental exposures, individual experiences, and epigenetic modifications.

By what molecular mechanisms do social determinants impact cardiometabolic risk?

While it is well known from numerous epidemiologic investigations that social determinants (socioeconomic, environmental, and psychosocial factors exposed to over the life-course) can dramatically impact cardiovascular health, the molecular mechanisms by which social determinants lead to poor cardiometabolic outcomes are not well understood. This review comprehensively summarizes a variety of current topics surrounding the biological effects of adverse social determinants (i.e., the biology of adversity), linking translational and laboratory studies with epidemiologic findings. With a strong focus on the biological effects of chronic stress, we highlight an array of studies on molecular and immunological signaling in the context of social determinants of health (SDoH). The main topics covered include biomarkers of sympathetic nervous system and hypothalamic-pituitary-adrenal axis activation, and the role of inflammation in the biology of adversity focusing on glucocorticoid resistance and key inflammatory cytokines linked to psychosocial and environmental stressors (PSES). We then further discuss the effect of SDoH on immune cell distribution and characterization by subset, receptor expression, and function. Lastly, we describe epigenetic regulation of the chronic stress response and effects of SDoH on telomere length and aging. Ultimately, we highlight critical knowledge gaps for future research as we strive to develop more targeted interventions that account for SDoH to improve cardiometabolic health for at-risk, vulnerable populations.

Depressive symptoms and other negative psychological states relate to ex vivo inflammatory responses differently for men and women: Cross-sectional and longitudinal evidence

An array of negative psychological states - including depressive symptoms, perceived stress, rumination, and negative affect - have been linked to immune function and inflammatory responses. Herein we show evidence of gender-dependent associations between ex vivo lipopolysaccharide (LPS)-stimulated cytokine responses and such psychological states, in both cross-sectional and longitudinal analyses from three annual waves (N = 162 at baseline, 67.3% female). In cross-sectional analyses (at baseline), gender moderated the associations of depressive symptoms (previously reported), perceived stress (B = -0.043, 95%CI [-0.080, -0.015]), rumination (B = -0.500, [-1.015, -0.232]), negative affect (B = -0.020, [-0.020, -0.005]), and positive affect (B = 0.024, [0.008, 0.047]) with LPS-stimulated cytokine responses. In each analysis, negative psychological states were positively associated with LPS-stimulated cytokine responses among men but negatively among women (with associations for positive affect in the opposite direction). In longitudinal analyses (across three annual measurements), similar associations were seen for depressive symptoms (B = -0.024, [-0.059, -0.004]), perceived stress (B = -0.045, [-0.069, -0.024]), and rumination (B = -0.381, [-0.622, -0.120]). These results indicate that gender is a critical factor in associations between a broad array of negative psychological states and inflammatory responses and identify one pathway by which gender may influence psychosomatic health.

IL-6 and IL-8 are likely associated with psychological status in treatment naïve general population

BACKGROUND

Levels of inflammatory markers are elevated in patients with psychological disorders. However, anti-psychological drugs have an effect on proinflammatory cytokine production and disturb their relationship. Limited evidence focuses on the inflammatory marker profile of psychological status before treatment. This study aimed to investigate the inflammatory biomarker profiles of psychological treatment-naive individuals.

METHODS

We included 790 psychological treatment-naive individuals from a longitudinal cohort study of Midlife in the United States (MIDUS). Symptoms of depression, anxiety, and stress were assessed by the Center for Epidemiologic Studies Depression Scale (CES-D) subscales, the Social Anxiety Scale (STAI), and Liebowitz Social Anxiety Scale (LSAS), the Perceived Stress Scale (PSS), respectively.

RESULTS

Spearman correlation analysis showed that a higher CESD total score was correlated with higher CRP (p=0.009), IL-6 (p=0.007), fibrinogen (p=0.036), E-selectin (p=0.018), ICAM-1 (p=0.013), and IL-8 (p=0.05) levels. Multivariate linear regression analysis showed that the CESD total score was positively associated with the levels of IL-6 (p=0.024) after adjustments. Moreover, the perceived stress score (PSS) was negatively associated with the levels of IL-8 (p=0.025). However, these associations were not significant after multiple testing (p=0.088, 0.091, respectively).

LIMITATIONS

The casual relationship cannot be drawn due to the cross-sectional design CONCLUSION: Overall, our results suggested IL-6 and IL-8 might play a important role in the pathogenesis of psychological disorder. Larger and longitude studies are needed to confirm our results.

Stress-buffering effect of social support on immunity and infectious risk during chemotherapy for breast cancer

Objective

This study investigated the stress-buffering effect of social support on immune function and infectious risk in women with breast cancer, during and after chemotherapy.

Method

Data were collected from 50 women with breast cancer before and after their chemotherapy, as well as three months later. Stress was measured by daily hassles related to cancer and social support by marital status (MS) and perceived support from friends (Ps-fr). Blood was collected to measure innate immune markers (i.e., T cells, NK cells and neutrophils). Infections were evaluated using a semi-structured interview. Moderation, mediation and moderated mediation models were computed to test the hypotheses.

Results

Higher stress at baseline was found to significantly predict a higher occurrence of infections during chemotherapy, but not three months later. The relationship between stress and infections was not significantly explained by any of the immune markers. The interaction between stress and social support was tested using MS alone and combined with Ps-fr. A protective effect of social support on the deleterious effect of stress on infectious risk was found. Single patients reporting lower Ps-fr showed the strongest association between stress and infections, while the weakest association was found in patients in a committed relationship with a higher level of Ps-fr.

Conclusions

Women experiencing more stress before the beginning of chemotherapy would appear to be at a higher risk of developing infections during their treatment. Results of this study also suggest that this effect could be buffered by the presence of a romantic partner and by higher Ps-fr.

Social Isolation Is Linked to Inflammation in Aging People With HIV and Uninfected Individuals

BACKGROUND

Even in the era of suppressive antiretroviral therapy, people with HIV (PWH) suffer greater exposure to inflammation than their uninfected peers. Although poor social support and social isolation have been linked to systemic inflammation in the general population, it is not known whether this is true also among PWH.

METHODS

People with and without HIV infection were enrolled in a community-based, single-center study. Primary predictors were the Medical Outcomes Study Social Support Survey, and outcomes were a panel of inflammatory biomarkers (ICAM-1, MCP-1, IL-6, IL-8, IP-10, C-reactive protein, D-dimer, VEGF, sCD14, and uPAR) in blood plasma and cerebrospinal fluid (CSF).

RESULTS

PWH had worse positive social support (P = 0.0138) and affectionate support (P = 0.0078) than did HIV- individuals. A factor analysis was used to group the biomarkers into related categories separately for each fluid. Levels of 3 of the 4 plasma factors were significantly higher in PWH than HIV- (ps = 0.007, 0.001, and 0.0005, respectively). Levels of 1 of the 3 CSF factors also were significantly higher in PWH than HIV- (P = 0.0194). In the combined PWH and HIV- cohort, poorer social support was associated with higher levels of a factor in plasma loading on MCP-1, IL-8, and VEGF (P = 0.020) and with a CSF factor loading on MCP-1 and IL-6 (P = 0.006).

CONCLUSION

These results suggest that enhancing social support might be an intervention to reduce inflammation and its associated adverse outcomes among PWH.

Interaction Mechanisms Between Major Depressive Disorder and Non-alcoholic Fatty Liver Disease

Major depressive disorder (MDD), which is highly associated with non-alcoholic fatty liver disease (NAFLD), has complex pathogenic mechanisms. However, a limited number of studies have evaluated the mutual pathomechanisms involved in MDD and NAFLD development. Chronic stress-mediated elevations in glucocorticoid (GC) levels play an important role in the development of MDD-related NAFLD. Elevated GC levels can induce the release of inflammatory factors and changes in gut permeability. Elevated levels of inflammatory factors activate the hypothalamic-pituitary-adrenal (HPA) axis, which further increases the release of GC. At the same time, changes in gut permeability promote the release of inflammatory factors, which results in a vicious circle among the three, causing disease outbreaks. Even though the specific role of the thyroid hormone (TH) in this pathogenesis has not been fully established, it is highly correlated with MDD and NAFLD. Therefore, changing lifestyles and reducing psychological stress levels are necessary measures for preventing MDD-related NAFLD. Among them, GC inhibitors and receptor antagonists may be key in the alleviation of early and mid-term disease progression. However, combination medications may be important in late-stage diseases, but they are associated with various side effects. Traditional Chinese medicines have been shown to be potential therapeutic alternatives for such complex diseases.

Autonomic nervous system activity predicts increasing serum cytokines in children

Systemic inflammation is associated with increased risk for prevalent and costly diseases, and animal models implicate the autonomic nervous system in the control of inflammatory processes. In humans, research on autonomic-immune connections has been much more limited, and has focused on single branch autonomic measures (i.e., either parasympathetic or sympathetic). The current study utilized cardiac autonomic balance (CAB), derived from dual-branch cardiac autonomic recordings, to test the relation between resting autonomic function and inflammatory reactivity to challenge in children.

METHODS

Participants included 96 children (51 boys, 45 girls) ages 9-11 years (mean age = 9.93 years, SD = 0.57 years). CAB values were calculated from standardized measures of parasympathetic and sympathetic activity, namely resting respiratory sinus arrhythmia and pre-ejection period data, respectively. Children provided two blood samples, one before and one following exposure to an acute social stressor or control condition. Serum was assayed for four cytokines that orchestrate inflammation: interleukin-6 (IL6), interleukin-8 (IL8), interleukin-10 (IL10), and tumor necrosis factor-alpha (TNFa).

RESULTS

We discovered large individual differences in inflammatory marker production across children, and no average main effect of stress condition. CAB significantly predicted these individual differences, such that children lower on CAB showed increasing serum cytokines from time 1 to time 2. In contrast, children with greater CAB tended to show declining inflammatory markers across the session.

DISCUSSION

Low cardiac autonomic balance (i.e., the combination of low parasympathetic and high sympathetic activity) may be a useful marker of proinflammatory tendencies in children, suggesting novel paths for early risk detection and intervention.

Minimally-invasive methods for examining biological changes in response to chronic stress: A scoping review

BACKGROUND

Nurse researchers are increasingly interested in incorporating biological indicators related to chronic stress, or repeated or constant exposure to psychological stressors. Minimally invasive collection methods may improve access to vulnerable populations.

OBJECTIVE

To map biological indicators measured through minimally invasive methods investigating biological changes in response to chronic stress.

DESIGN, DATA SOURCES, AND METHODS

The paper seeks to answer two questions: What are the characteristics of the minimally-invasive methods used to measure the biological correlates of chronic stress? What are the limitations regarding the use of the minimally-invasive methods and/or biological indicators identified above? Authors completed a scoping review following guidelines from the Joanna Briggs Institute Manual and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for Scoping Reviews. A literature search was completed in PubMed, PsycINFO, and Scopus. 2518 articles were screened and 145 studies were included. Data were extracted using a standardized extraction tool, compiled, and coded.

RESULTS

Studies included minimally-invasive methods to measure the hypothalamic-adrenal-pituitary axis (N = 173), immune and inflammatory markers (N = 118), and adult neurogenesis (N = 6). Cortisol was most frequently measured (N = 136), usually in saliva (N = 86). Studies included a variety of limitations for the methods and indicators, including concerns about timing and accuracy of collection, frequency of sampling, and controlling for acute stressors.

CONCLUSIONS

Nurse researchers have access to many minimally-invasive methods to measure altered biological processes related to chronic stress. A gap identified by this review is the paucity of minimally-invasive methods for investigating neurogenesis; the measurement of brain derived neurotrophic factor in plasma is a distal proxy and further research is needed to test the response of peripheral levels to psychosocial stress interventions. Additionally, while this scoping review allows nurse researchers to consider possible biological indicators to include in their research, future research is still needed on some of the basic premises of stress research, including agreement on the conceptualization of chronic stress.

Depression and fatigue in multiple sclerosis: Relation to exposure to violence and cerebrospinal fluid immunomarkers

Multiple sclerosis (MS) is a neuroinflammatory condition characterized by chronic dysregulation of immune responses leading to repeated episodes of inflammation in the central nervous system. Depression and fatigue are common among MS patients, even in early disease phases, and the disease course can be negatively affected by stressful events. IL-6 and IL-8 have been associated with depression and stressful life events in non-MS patients. The aim of this study was to examine the relationships between depression, fatigue, and exposure to violence, with IL-6 and IL-8 levels in the cerebrospinal fluid (CSF) of MS patients. Levels of IL-6 and -8 were analyzed in the CSF of 47 patients with relapsing-remitting MS. Correlations between IL-6 and IL-8 levels and self-rated depression and fatigue symptoms, as well as clinician-rated history of being exposed to interpersonal violence, were analyzed with correction for age, sex and MS disability status. IL-6 correlated significantly (p < 0.05) with depressive symptoms (adjusted Spearman's ρ = 0.39), fatigue (ρ = 0.39), and exposure to violence in adult life (ρ = 0.35). Depression correlated with both fatigue and being exposed to violence. Associations were not present among patients exposed to disease modifying drugs. In exploratory analyses, the relationship between exposure to violence and IL-6 was non-significant when controlled for depression. Further research should focus on replication of these results, as well as exploring the impact of stressful life events on immune regulation and the clinical characteristics and prognosis of MS patients.

A meta-analysis of chemokines in major depression

Chemokines are increasingly recognised as playing a role in depression. Here we meta-analyse the data on concentrations of all chemokines in patients diagnosed with a major depression versus healthy controls. We included studies which utilised Diagnostic and Statistical Manual (DSM)-IV diagnostic criteria for major depression, participants free from major medical conditions, studies with healthy controls, and unstimulated measurements of chemokines. We only included chemokines which had ≥3 studies performed. Two chemokines and 15 studies in total met criteria for this meta-analysis; 8 for Monocyte Chemotactic Protein (MCP)-1/CCL2 (n=747), and 7 for Interleukin (IL)-8/CXCL8 (n=560). There were significantly higher concentrations of CCL2/MCP-1 in depressed subjects compared with control subjects - overall mean difference of 36.43pg/mL (95% CI: 2.43 to 70.42). There was significant heterogeneity across these studies (I2=98.5%). The estimates of mean difference between the control and depression groups did not remain significant when the trim-and-fill procedure was used to correct for publication bias. There was no significant difference in concentrations of IL-8/CXCL8 in depressed subjects compared with control subjects. Significant heterogeneity was found across these studies (I2=96.7%). The estimates of mean difference between the control and depression groups remained non-significant when the trim-and-fill procedure was used to correct for publication bias. This meta-analysis reports significantly heterogeneity in this field among studies. There are higher concentrations of the chemokine MCP-1/CCL2 in depressed subjects compared with control subjects, and no differences for IL-8/CXCL8. More high quality research and consistent methodologies are needed in this important area of enquiry.

Fish oil supplementation does not lower C-reactive protein or interleukin-6 levels in healthy adults

BACKGROUND

The n-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may prevent a range of chronic conditions through anti-inflammatory actions. However, as clinical trials using these fatty acids for primary prevention are yet unavailable, their putative role in disease prevention rests, in part, on evidence of anti-inflammatory actions in healthy individuals.

OBJECTIVE

To investigate in a double-blind, placebo-controlled clinical trial whether supplementation with a moderate dose of EPA+DHA reduces common biomarkers of chronic, systemic inflammation in healthy individuals.

METHODS

A total of 261 healthy individuals aged 30-54 years who were free of inflammatory conditions and consumed ≤ 300 mg per day EPA+DHA were included in the study. Participants were randomly assigned to 18 weeks of either fish oil supplementation providing 1400 mg per day EPA+DHA or matching placebo. Outcome measures were serum levels of C-reactive protein (CRP) and interleukin (IL)-6. In a substudy, ex vivo cytokine production was measured. Missing data for CRP and IL-6 were estimated using regression imputation. Data analyses conformed to intention-to-treat principles.

RESULTS

Participant blinding was verified. Red blood cell EPA+DHA increased by 64% in the active treatment group, but serum CRP and IL-6 were not affected by supplementation (P ≥ 0.20). Findings were consistent with and without imputed values and across subgroups. Similarly, EPA+DHA supplementation did not alter ex vivo production of four pro-inflammatory cytokines (P ≥ 0.20).

CONCLUSIONS

Supplementation with 1400 mg EPA+DHA did not reduce common markers of systemic inflammation in healthy adults. Whether this or a higher dose affects other measures of inflammation, oxidative stress or immune function warrants examination.

Effect of the maternal-fetal interface immunoregulation on the occurrence of intrahepatic cholestasis of pregnancy

Maternal immune tolerance of the fetus is indispensable for a healthy pregnancy. Currently, the study of the immune microenvironment of the maternal-fetal interface has been a heated topic in reproductive immunology research. More and more studies show that the immune imbalance in the maternal-fetal interface plays a very important role in the incidence of intrahepatic cholestasis of pregnancy (ICP). However, the precise etiology and mechanism of immune imbalance in the occurrence of ICP is still unknown. In order to clarify the potential immunologic mechanisms of ICP, this review summarizes the recent studies of the decidual immunology microenvironment and the potential immunologic mechanisms related to the development of ICP.

Source-specific social support and circulating inflammatory markers among white-collar employees

BACKGROUND

Despite known beneficial effects of social support on cardiovascular health, the pathway through which sources of support (supervisor, coworkers, family/friends) influence inflammatory markers is not completely understood.

PURPOSE

We investigated the independent and moderating associations between social support and inflammatory markers.

METHODS

A total of 137 male white-collar employees underwent a blood draw for measurement of high-sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), monocyte and leukocyte counts, and completed a questionnaire on social support.

RESULTS

Multivariable linear regression analyses controlling for covariates revealed that supervisor support was inversely associated with IL-6 (β = -0.24, p < 0.01) while coworker support was marginally associated with TNF-α (β = -0.16, p < 0.10). Support from family/friends was not associated with inflammatory markers.

CONCLUSION

Social support from the immediate supervisor may be a potential mechanism through which social support exerts beneficial effects on inflammatory markers in working men.

Neuro-immuno-endocrine modulation in marathon runners

OBJECTIVE

Sports practice alters the homeostasis of athletes. To achieve homeostatic equilibrium, the integrated action of the neuroendocrine and immune systems is necessary. Here we studied the relation between cytokines, hormones and mood states in marathon runners.

METHODS

A total of 20 male recreational marathon runners (mean age = 35.7 ± 9 years) and 20 male sedentary individuals (mean age = 35.5 ± 7 years) were recruited. We compared the serum levels of growth hormone (GH), cortisol and interleukins 8 and 10 and the amounts of these two cytokines spontaneously produced by peripheral blood mononuclear cells. Blood samples of the sedentary group were collected at rest. Blood from the marathon runners was collected at rest (baseline: 24 h before the race), immediately after a marathon and 72 h after a marathon. Mood state analysis in both groups was performed using the 24-item Brunel Mood Scale (BRUMS).

RESULTS

Our results showed that, at rest, levels of interleukins 8 and 10 in the supernatant of culture cells, the serum concentration of GH, and tension and vigour (evaluated using the BRUMS), were significantly higher in athletes compared to sedentary people. Immediately after the race all serum parameters analysed were statistically higher than baseline values. At 72 h after the marathon, serum levels of hormones and interleukins returned to values at rest, but the concentrations of interleukins in the supernatant of culture cells showed a significant reduction compared to values at rest.

CONCLUSION

The higher serum levels of GH in athletes at rest and the higher production of cytokines in culture without previous stimulus suggest that marathon runners present mechanisms that may be associated with preparing the body to perform prolonged strenuous exercise, such as a marathon.

Immune responses to stress after stress management training in patients with rheumatoid arthritis

Introduction

Psychological stress may alter immune function by activating physiological stress pathways. Building on our previous study, in which we report that stress management training led to an altered self-reported and cortisol response to psychological stress in patients with rheumatoid arthritis (RA), we explored the effects of this stress management intervention on the immune response to a psychological stress task in patients with RA.

Methods

In this study, 74 patients with RA, who were randomly assigned to either a control group or a group that received short stress management training, performed the Trier Social Stress Test (TSST) 1 week after the intervention and at a 9-week follow-up. Stress-induced changes in levels of key cytokines involved in stress and inflammatory processes (for example, interleukin (IL)-6 and IL-8) were assessed.

Results

Basal and stress-induced cytokine levels were not significantly different in patients in the intervention and control groups one week after treatment, but stress-induced IL-8 levels were lower in patients in the intervention group than in the control group at the follow-up assessment.

Conclusions

In line with our previous findings of lower stress-induced cortisol levels at the follow-up of stress management intervention, this is the first study to show that relatively short stress management training might also alter stress-induced IL-8 levels in patients with RA. These results might help to determine the role of immunological mediators in stress and disease.

Trial registration

The Netherlands National Trial Register (NTR1193)

Social support predicts inflammation, pain, and depressive symptoms: longitudinal relationships among breast cancer survivors

OBJECTIVE

Pain and depressive symptoms are commonly experienced by cancer survivors. Lower social support is linked to a variety of negative mental and physical health outcomes among survivors. Immune dysregulation may be one mechanism linking low social support to the development of pain and depressive symptoms over time. Accordingly, the goal of the present study was to examine the relationships among survivors' social support, pain, depressive symptoms, and inflammation.

METHODS

Breast cancer survivors (N=164, stages 0-IIIA) completed two study visits, one before any cancer treatment and the other 6 months after the completion of surgery, radiation, or chemotherapy, whichever came last. Women completed self-report questionnaires assessing social support, pain, and depressive symptoms, and provided a blood sample at both visits.

RESULTS

Survivors with lower social support prior to treatment experienced higher levels of pain and depressive symptoms over time than their more socially supported counterparts. Furthermore, women with lower pretreatment social support had higher levels of IL-6 over time, and these elevations in IL-6 predicted marginally larger increases in depressive symptoms.

CONCLUSIONS

The results of this study suggest that social support at the time of diagnosis predicts the post-treatment development of pain, depressive symptoms, and inflammation. Consequently, early interventions targeting survivors' social networks could improve quality of life during survivorship.

Urinary interleukin-8 is a biomarker of stress in emergency physicians, especially with advancing age--the JOBSTRESS* randomized trial

Background

Emergency physicians are exposed to greater stress during a 24-hour shift (24 hS) than a 14-hour night shift (14 hS), with an impact lasting several days. Interleukin-8 (IL-8) is postulated to be a chronic stress biomarker. However, no studies have tracked IL-8 over several shifts or used it for monitoring short-term residual stress. The IL-8 response to the shifts may also increase with age. Conveniently, IL-8 can be measured non-intrusively from urine.

Methods

We conducted a shifts-randomized trial comparing 17 emergency physicians’ urinary IL-8 levels during a 24 hS, a 14 hS, and a control day (clerical work on return from leave). Mean levels of IL-8 were compared using a Wilcoxon matched-pairs test. Independent associations of key factors including shifts, stress, and age with IL-8 levels were further assessed in a multivariable generalized estimating equations model.

Results

Mean urinary IL-8 levels almost doubled during and after a 24 hS compared with a 14 hS or a control day. Furthermore, IL-8 levels failed to return to control values at the end of the third day after the shift despite a rest day following the 24 hS. In the multivariable model, engaging in a 24 hS, self-reported stress, and age were independently associated with higher IL-8 levels. A 24 hS significantly increased IL-8 levels by 1.9 ng (p = .007). Similarly, for every unit increase in self-reported stress, there was a 0.11 ng increase in IL-8 levels (p = .003); and for every one year advance in age of physicians, IL-8 levels also increased by 0.11 ng (p = .018).

Conclusion

The 24 hS generated a prolonged response of the immune system. Urinary IL-8 was a strong biomarker of stress under intensive and prolonged demands, both acutely and over time. Because elevated IL-8 levels are associated with cardiovascular disease and negative psychological consequences, we suggest that emergency physicians limit their exposure to 24 hS, especially with advancing age.

Cholinergic receptors modulate immune complex-induced inflammation in vitro and in vivo

Cholinergic neural output has been shown to modulate innate immune responses to infection, injury and ischemia through stimulation of α7 nicotinic acetylcholine receptors (α7nAChR) on mononuclear phagocytes. We tested the hypothesis that cholinergic neurotransmitters, similar to those released through activation of a neural reflex, regulate responses to products of the adaptive immune system, specifically immune complex (IC)-mediated activation of effector cells. In this study, we show that stimulation of α7nAChR on human polymorphonuclear neutrophils (PMNs) and blood mononuclear phagocytes in vitro attenuates C5aR- and FcγR-triggered generation of reactive oxygen species, expression of leukocyte markers involved in cell recruitment and adhesion, and release of TNF-α and other proinflammatory cytokines. We show that this pathway is operative in vivo. Ligation of cholinergic receptors blunts IC-triggered responses in the reverse peritoneal Arthus reaction in mice. The selective 7nAChR agonist GTS21 decreased PMN accumulation and release of cytokines and chemokines at sites of IC deposition. In addition, mice lacking α7nAChR had exaggerated responses to reverse peritoneal Arthus reaction characterized by increased infiltration of PMNs and elevated of levels of TNF-α and CXCL1 in peritoneal fluid compared with wild-type mice. Taken together, these findings suggest that cholinergic output has the potential to exert tonic inhibitory activity that dampens responses to ICs and C5a and thus may be a target to minimize tissue damage in autoimmune diseases.

Acute psychological stress results in the rapid development of insulin resistance

In recent years, the roles of chronic stress and depression as independent risk factors for decreased insulin sensitivity and the development of diabetes have been increasingly recognized. However, an understanding of the mechanisms linking insulin resistance and acute psychological stress are very limited. We hypothesized that acute psychological stress may cause the development of insulin resistance, which may be a risk factor in developing type 2 diabetes. We tested the hypothesis in a well-established mouse model using 180 episodes of inescapable foot shock (IES) followed by a behavioral escape test. In this study, mice that received IES treatment were tested for acute insulin resistance by measuring glucose metabolism and insulin signaling. When compared with normal and sham mice, mice that were exposed to IES resulting in escape failure (defined as IES with behavioral escape failure) displayed elevated blood glucose levels in both glucose tolerance and insulin tolerance tests. Furthermore, mice with IES exposure and behavioral escape failure exhibited impaired hepatic insulin signaling via the insulin-induced insulin receptor/insulin receptor substrate 1/Akt pathway, without affecting similar pathways in skeletal muscle, adipose tissue, and brain. Additionally, a rise in the murine growth-related oncogene KC/GRO was associated with impaired glucose metabolism in IES mice, suggesting a mechanism by which psychological stress by IES may influence glucose metabolism. The present results indicate that psychological stress induced by IES can acutely alter hepatic responsiveness to insulin and affect whole-body glucose metabolism.

Psychological pathways linking social support to health outcomes: a visit with the "ghosts" of research past, present, and future

Contemporary models postulate the importance of psychological mechanisms linking perceived and received social support to physical health outcomes. In this review, we examine studies that directly tested the potential psychological mechanisms responsible for links between social support and health-relevant physiological processes (1980s-2010). Inconsistent with existing theoretical models, no evidence was found that psychological mechanisms such as depression, perceived stress, and other affective processes are directly responsible for links between support and health. We discuss the importance of considering statistical/design issues, emerging conceptual perspectives, and limitations of our existing models for future research aimed at elucidating the psychological mechanisms responsible for links between social support and physical health outcomes.

Negative emotions and cytokines in maternal and cord serum at preterm birth

PROBLEM

This study investigates whether affectivity differs between mothers delivering preterm and term and whether maternal and umbilical cord serum cytokines differ between these groups. Further, whether there are associations between mothers' emotions and maternal and cord cytokines at preterm and term birth.

METHOD OF STUDY

Twenty-seven mothers delivering preterm and 37 mothers delivering at term reported positive/negative affect and previous depressive symptoms during pregnancy. Blood samples from mothers in labor and cord samples (23 preterm and 33 term) were analyzed for cytokines.

RESULTS

Maternal IL-8 was lower at preterm delivery compared with term. In the preterm group only, associations were found between negative emotions and maternal IL-6, IL-8 and cord IL-6, IL-8, IL-10, IL-13, and IL-18.

CONCLUSION

The findings indicate associations in preterm delivery between negative emotions and both maternal and neonate immune activity. Future studies should investigate whether such associations are part of the etiology of preterm delivery.

Immune function and HPA axis activity in free-ranging rhesus macaques

In mammals, the hypothalamic-pituitary-adrenal (HPA) axis and immune system play an important role in the maintenance of homeostasis. Dysregulation of either system resulting, for example, from psychosocial or reproductive stress increases susceptibility to disease and mortality risk, especially in aging individuals. In a study of free-ranging rhesus macaques, we examined how female age, reproductive state, social rank, and body condition influence (i) aspects of cytokine biology (plasma concentrations of interleukin-1 receptor antagonist (IL-1ra), IL-6 and IL-8), and (ii) HPA axis activity (plasma and fecal glucocorticoid levels). We also assessed individual differences in cytokine and hormone concentrations over time to determine their consistency and to investigate relations between these two indicators of physiological regulation and demand. Female monkeys showed marked increases in HPA axis activity during pregnancy and lactation, and increased circulating levels of IL-1ra with advancing age. Inter-individual differences in IL-1ra and IL-8 were consistent over successive years, suggesting that both are stable, trait-like characteristics. Furthermore, the concentrations of fecal glucocorticoid hormones in non-pregnant, non-lactating females were correlated with their plasma cortisol and IL-8 concentrations. Some individuals showed permanently elevated cytokine levels or HPA axis activity, or a combination of the two, suggesting chronic stress or disease. Our results enhance our understanding of within- and between-individual variation in cytokine levels and their relationship with glucocorticoid hormones in free-ranging primates. These findings can provide the basis for future research on stress and allostatic load in primates.

Gender differences in stimulated cytokine production following acute psychological stress

Emerging evidence suggests that acute psychological stress modulates inflammatory competence; however, not all findings are consistent. Gender is one factor that may impact magnitude of response. To explore this possibility, we examined the effects of acute mental stress on lipopolysaccharide-induced production of pro-inflammatory cytokines interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha among a relatively healthy sample of midlife men (n=28) and women (n=34). Blood samples for the assessment of cytokine production were drawn before, immediately after, and 30min following subjects' performance of an evaluative speech task. Relative to baseline evaluations, the speech stressor elicited a significant increase in stimulated production of all 3 pro-inflammatory cytokines, as measured 30min following the end of the task. There were no gender differences in the magnitude of this effect. However, men showed a significant decrease in cytokine production from before to immediately following the stressor, whereas women showed no change across this period. Menopausal status partially accounted for these gender differences, with post-menopausal women displaying greater increases in IL-6 and TNF-alpha production from baseline-to-post-task when compared to men. These data provide further evidence that acute psychological stress primes the immune system to mount larger inflammatory responses and initial support for gender differences in the patterning of stress-related cytokine activity. In addition, this study presents novel evidence that post-menopausal women may be particularly susceptible to stress-related inflammatory responses. The possibility that this contributes to the increased risk of inflammatory disease observed among older women warrants investigation.

Gender, race/ethnicity, personality, and interleukin-6 in urban primary care patients

Gender, race/ethnicity, and personality are markers of significant psychosocial and biological variability. Each may have implications for allostatic load and resulting inflammatory processes, yet findings have been largely mixed. We investigated whether women, minorities, and those higher in Neuroticism and lower in Extraversion were at risk for elevated circulating levels of the pro-inflammatory cytokine interleukin (IL)-6 in a sample of 103 middle aged and older urban primary care patients. Regression analyses controlling for age, education, current depression levels, and chronic medical conditions revealed that women, minorities, and individuals lower in Extraversion had higher circulating levels of IL-6. Analyses of more specific personality traits revealed that the sociability and positive emotions components of Extraversion were unassociated with IL-6, but the activity facet-reflecting dispositional vigor and energy-was robustly associated with IL-6. The difference between high (+1 Standard Deviation (SD)) and low (-1 SD) trait activity was sufficient to shift IL-6 levels beyond a previously established high risk cut-point in both white and minority women. These findings suggest that while broad group differences between genders and races/ethnicities exist, personality represents an important source of individual differences in inflammation within groups. Future work should examine to what extent IL-6 levels are linked to temperament or genetic activity levels vs. physical activity itself, and whether IL-6 levels may be reduced by boosting regular activity levels in demographic segments such as women and minorities who appear susceptible to greater inflammation.

Normative variation in self-reported sleep quality and sleep debt is associated with stimulated pro-inflammatory cytokine production

Activation of innate inflammatory pathways, marked by increased production of pro-inflammatory cytokines, has been proposed as a potential mechanism linking poor sleep and inflammatory disease risk. In the present study, we examined associations of self-reported sleep quality and duration, and a calculated measure of sleep debt with the production of pro-inflammatory cytokines, interleukin (IL)-6, IL-1beta, and tumor necrosis factor (TNF)-alpha among a community sample of 156 healthy adults. Bivariate correlations revealed an inverse association between sleep quality and production of all the three pro-inflammatory cytokines that was retained for IL-1beta after controlling for demographic and health characteristics. Hierarchical linear regressions also revealed that higher sleep debt scores predicted greater production of IL-1beta and IL-6 after adjusting for covariates. Secondary analyses showed an interaction between sleep debt and body mass index (BMI) in the prediction IL-1beta, suggesting that the impact of sleep debt on cytokine production is greater among participants with lower BMI scores. Further exploration of this potential psychophysiological pathway linking sleep difficulty and inflammatory disease susceptibility is warranted.

Stress assessment in acute care department nurses by measuring interleukin-8

BACKGROUND

Cytokines, such as interleukin (IL)-8, have been shown to be related to depressive symptoms or inflammatory diseases and may be useful as stress biomarkers.

AIM

This study was to assess whether urinary IL-8 levels were reliable indicators of stress among acute care department (AD) nurses.

METHODS

A total of 118 nurses participated in the study. Urinary IL-8 levels of 49 AD nurses were compared with levels of a control group of 69 chronic care department (CD) nurses.

RESULTS

The urinary IL-8 levels of AD nurses, who reported a higher level of professional stress, were higher than the levels of CD nurses (P < 0.01).

CONCLUSION

Measurement of urinary IL-8 may be an appropriate biomarker for stress assessment in nurses.

Social and emotional support and its implication for health

PURPOSE OF REVIEW

Recent research findings from selected publications focusing on links between social support and physical health are summarized.

RECENT FINDINGS

Current research is extending our understanding of the influences of social support on health. Many epidemiological studies have concentrated on further linking measures of social support to physical health outcomes. A few studies are now moving into newer areas, such as emphasizing health links with support receipt and provision. Researchers are also interested in outlining relevant pathways, including potential biological (i.e. inflammation) and behavioral (i.e. health behaviors) mechanisms. Interventions attempting to apply basic research on the positive effects of social support are also widespread. Although the longer term effects of such interventions on physical health remain to be determined, such interventions show promise in influencing the quality of life in many chronic disease populations.

SUMMARY

Recent findings often show a robust relationship in which social and emotional support from others can be protective for health. The next generation of studies must explain, however, why this relationship exists and the specificity of such links. This research is in its infancy but will be crucial in order to better tailor support interventions that can impact on physical health outcomes.

Obesity, depression, and chronic low-grade inflammation in women with polycystic ovary syndrome

BACKGROUND AND OBJECTIVE

Women with polycystic ovary syndrome (PCOS) present with multiple risk factors for cardiovascular diseases at a young age, including obesity and chronic low-grade inflammation. Since depression is common in PCOS, this study aimed to address whether depression correlates with indices of chronic low-grade inflammation beyond the association with obesity.

METHODS

Serum concentrations of IL-6, the stimulated production of IFN-gamma, TNF-alpha, IL-2, IL-4, IL-5, and IL-10, leukocyte numbers, and hsCRP were analyzed in 57 PCOS patients and 28 healthy women, together with clinical parameters, including body mass index (BMI), testosterone, and insulin resistance (HOMA-IR), and psychological parameters, including Beck Depression Inventory (BDI) and health-related quality-of-life (SF-36) scores.

RESULTS

PCOS patients demonstrated significantly increased hsCRP, IL-6, and leukocyte numbers. Group differences in IL-6 and leukocyte numbers, but not hsCRP, disappeared after controlling for BMI. The stimulated production of IFN-gamma, TNF-alpha, IL-2, IL-4, and IL-5 was significantly decreased, irrespective of BMI. In PCOS, hsCRP, IL-6, and leukocyte numbers were correlated with BMI, HDL, diastolic blood pressure, and with insulin resistance. On the other hand, no correlations were found with depression scores or with PCOS-specific endocrine abnormalities. In regression models, BMI was a significant predictor of the key immune markers, and explained a large amount of variance, whereas BDI was not included in either model.

CONCLUSIONS

These data confirm that obesity plays a pivotal role in inflammatory processes relevant to cardiovascular risk in women with PCOS. However, even lean PCOS patients may display subtle alterations in specific aspects of immunity. Our findings did not support a correlation of depression with chronic low-grade inflammation in PCOS.

Chronic stress and regulation of cellular markers of inflammation in rheumatoid arthritis: implications for fatigue

OBJECTIVES

This study examined whether chronic interpersonal stress is associated with cellular markers of inflammation and regulation of these responses by in vitro doses of glucocorticoids in rheumatoid arthritis (RA) patients. The association between these markers of inflammation and fatigue was also tested.

METHODS

Fifty-eight RA patients completed up to 30 daily ratings of the stressfulness of their interpersonal relations. Interleukin-6 (IL-6) production was analyzed in lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cell cultures with and without varying concentrations of the glucocorticoid hydrocortisone. In addition, plasma levels of IL-6 and C-reactive protein (CRP) were analyzed, and subjective ratings of fatigue and pain were obtained on the day of blood sampling.

RESULTS

Multilevel modeling showed that higher chronic interpersonal stress was associated with greater stimulated IL-6 production (p<0.05) as well as greater resistance to hydrocortisone inhibition of IL-6 production (p<0.05). These relations were not accounted for by demographic factors, body mass index, or steroid medication use. Stimulated production of IL-6, in turn, was associated with greater levels of self-reported fatigue, controlling for pain (p<0.05). Neither chronic stress ratings nor fatigue symptoms were related to plasma levels of IL-6 or CRP (ps>.05).

CONCLUSIONS

Among RA patients, chronic interpersonal stress is associated with greater stimulated cellular production of IL-6 along with impairments in the capacity of glucocorticoids to inhibit this cellular inflammatory response. Moreover, these findings add to a growing body of data that implicate heightened proinflammatory cytokine activity in those at risk for fatigue symptoms.

Stimulated production of proinflammatory cytokines covaries inversely with heart rate variability

OBJECTIVE

To examine whether high-frequency heart rate variability, an indirect measure of parasympathetic (vagal) control over variations in heart rate, is associated with immune reactivity to an in vitro inflammatory challenge. Convergent evidence from the animal literature shows that the autonomic nervous system plays a key role in regulating the magnitude of immune responses to inflammatory stimuli. Signaling by the parasympathetic system inhibits the production of proinflammatory cytokines by activated monocytes/macrophages and thus decreases local and systemic inflammation. As yet, no direct human evidence links parasympathetic activity to inflammatory competence.

METHODS

We examined the relationship of variations in heart rate, recorded during paced respiration, to lipopolysaccharide-induced production of the inflammatory cytokines interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF)-alpha, and IL-10 among a community sample of 183 healthy adults (mean age = 45 years; 59% male; 92% White, 7% African-American).

RESULTS

Consistent with animal findings, higher derived estimates of vagal activity measured during paced respiration were associated with lower production of the proinflammatory cytokines TNF-alpha and IL-6 (r = -.18 to -.30), but were not related to production of the anti-inflammatory cytokine IL-10. These associations persisted after controlling for demographic and health characteristics, including age, gender, race, years of education, smoking, hypertension, and white blood cell count.

CONCLUSIONS

These data provide initial human evidence that vagal activity is inversely related to inflammatory competence, raising the possibility that vagal regulation of immune reactivity may represent a pathway linking psychosocial factors to risk for inflammatory disease.