Stimulated production of proinflammatory cytokines covaries inversely with heart rate variability

Exercise-induced changes in plasma S-Klotho levels are associated with the obtained enhancements of heart rate variability in sedentary middle-aged adults: the FIT-AGEING study

The shed form of the Klotho protein (S-Klotho) is considered a biomarker of longevity, but it is still unknown whether the levels are related to heart rate (HR) and heart rate variability (HRV); both of them greatly influenced by the ageing process, physical fitness, exercise, and health status. This study aimed (i) to investigate the association between S-Klotho plasma levels with HR and HRV parameters and (ii) to examine the association of exercise-induced changes in S-Klotho and those obtained in HR and HRV parameters after a 12-week exercise intervention in sedentary middle-aged adults. Sixty-six sedentary middle-aged adults participated in this study (50% women; 45-65 years old). Participants were randomized into 4 groups: (a) a control group (no exercise), (b) a physical activity recommendation from the World Health Organization group, (c) a high-intensity interval training group, and (d) a high-intensity interval training group adding whole-body electromyostimulation. S-Klotho plasma levels, HR, and HRV parameters (SDNN, RMSSD, high frequency, stress score, and sympathetic/parasympathetic ratio) were measured. At baseline, S-Klotho plasma levels were not related to HR and HRV parameters. After the intervention, exercise-induced changes in S-Klotho plasma levels were positively associated with changes in SDNN (β=0.261; R2=0.102; p=0.014) and negatively related to changes in stress score and sympathetic/parasympathetic ratio (all β=-0.257; R2 ranges between 0.092 and 0.131; all p<0.020). Our study suggests that higher S-Klotho plasma levels are related to increased vagal influence and reduced sympathetic tone in the autonomic nervous system in sedentary middle-aged adults after different training programs. ClinicalTrials.gov identifier: CT03334357.

Fit-Fat Index is better associated with heart rate variability compared to fitness and fatness alone as indicators of cardiometabolic human health

OBJECTIVES

Cardiorespiratory fitness and fatness indicators have been related to heart rate variability (HRV) parameters. The Fit-Fat Index (FFI) is a single index combining cardiorespiratory fitness and fatness indicators. To the best of our knowledge, no studies have previously analyzed whether FFI are related to cardiac autonomic nervous system activity assessed through HRV parameters. This study aimed (i) to examine the association of cardiorespiratory fitness, fatness indicators, and FFI with HRV parameters; and (ii) to report what of the different fatness indicators included in FFI is better associated with HRV parameters in sedentary adults.

METHODS

One hundred and fifty healthy adults (74 women; 76 men), aged between 18 and 65 years old, participated in this cross-sectional study. We measured cardiorespiratory fitness (maximal oxygen consumption) and fatness indicators (waist-to-height ratio [WHR], fat mass percentage [FM%] and visceral adipose tissue [VAT]). Three FFIs were calculated as the quotient between cardiorespiratory fitness and one out of three possible fatness indicators: Fit-Fat Index calculated waist-to-height ratio (FFIWHR ), Fit-Fat Index calculated with FM% (FFIFM% ), and Fit-Fat Index calculated with VAT (FFIVAT ). HRV parameters were measured in resting conditions using a Polar RS800CX.

RESULTS

FFIWTHR , FFIFM% and FFIVAT were related to different HRV parameters (β ranges between -0.507 and 0.529; R2 ranges between 0.096 and 0.275; all p < .001) and the association was stronger with HRV parameters than the isolated fitness or fatness indicators (β ranges between -0.483 and 0.518; R2 ranges between 0.071 and 0.263; all p < .001). FFIVAT was the index more consistently associated with HRV parameters (β ranges between -0.507 and 0.529; R2 ranges between 0.235 and 0.275; all p < .001).

CONCLUSION

Our study suggests that compound FFIs are better predictors of HRV parameters than either cardiorespiratory fitness or fatness indicators alone. The FFIVAT was the best index in terms of its association to HRV.

The Vagal Nerve, Inflammation, and Diabetes-A Holy Triangle

Type 2 diabetic mellitus (T2DM) is a common chronic disease and a substantial risk factor of other fatal illnesses. At its core is insulin resistance, where chronic low-level inflammation is among its main causes. Thus, it is crucial to modulate this inflammation. This review paper provides scientific neuroimmunological evidence on the protective roles of the vagal nerve in T2DM. First, the vagus inhibits inflammation in a reflexive manner via neuroendocrine and neuroimmunological routes. This may also occur at the level of brain networks. Second, studies have shown that vagal activity, as indexed by heart-rate variability (HRV), is inversely related to diabetes and that low HRV is a predictor of T2DM. Finally, some emerging evidence shows that vagal nerve activation may reduce biomarkers and processes related to diabetes. Future randomized controlled trials are needed to test the effects of vagal nerve activation on T2DM and its underlying anti-inflammatory mechanisms.

Higher Resting Cardiovagal Activity Predicts Larger Decrease of Depressive Symptoms in Inpatients Treated for Stress-Related Depression

Abstract. Depression is one of the most prevalent mental disorders, with treatment outcomes generally being unsatisfactory. The identification of outcome predictors could contribute to improving diagnosis, treatment, and outcome. Heart rate variability (HRV), an index of cardiovagal activity, has been proposed as a potential correlate of depression as well as a predictor of treatment effectiveness. The aim of the present study was to examine if HRV at baseline could predict the outcome of inpatient treatment for stress-related depressive disorder (SRDD). Depressive symptoms of n = 57 inpatients with an SRDD, who were treated in a specialized burnout ward, were assessed using the Beck Depression Inventory (BDI) at the beginning, the end of treatment, and at 3-month follow-up. HRV (i.e., RMSSD, the root mean square of successive RR interval differences) was determined from a five-minute measurement in the supine position. RMSSD was not significantly associated with the BDI score at the beginning, end, and follow-up. Higher RMSSD was revealed to be a significant predictor of a stronger decrease in depressive severity from the beginning to the end of the treatment. Thereby, the regression model explained 7.6% of the total variance in the BDI decrease. The results revealed initial HRV to predict a larger decrease in depressive severity. Therefore, resting HRV represents a physiological resource and index of successful neurovisceral interaction, which supports inpatients in benefitting from specialized treatment.

The cholinergic anti-inflammatory pathway in humans: State-of-the-art review and future directions

The parasympathetic nervous system modulates inflammation through efferent vagus nerve signaling. Tracey (2002) termed this process as the cholinergic anti-inflammatory pathway (CAP). Interest in the potential practical use of this immune-modulatory process is increasing alongside increasing appreciation for the role of systemic inflammation in the etiology of somatic and psychological disease. A diverse literature exists providing expansive correlational evidence and some preliminary experimental evidence of the CAP in humans. However, so far this literature has not been well integrated and critically evaluated. This review describes the current state-of-the-art of research into vagus nerve driven parasympathetic control of inflammation in humans. Substantial limitations and gaps in the literature are identified, and promising directions for future research are highlighted.

Associations between heart rate variability, peripheral inflammatory markers and major depressive disorder

BACKGROUND

Measures for the irregularity of the heartbeat, for example respiratory sinus arrhythmia, have been implicated as a measure for restorative functions of the vegetative nervous system.

METHODS

In the current observational study, we investigated 265 subjects, 70 of whom had a lifetime history of major depression, with a plethysmographic heartbeat monitor, blood sampling, as well as a range of psychiatric questionnaires.

RESULTS

Subjects with a history of MDE had significantly reduced respiratory sinus arrhythmia (RSA) as compared to never-depressed controls; in the whole sample, higher RSA went with lower anxiety/fear variables, especially in subscores related to cardiac symptoms as well as being afraid of dying. A reduced RSA was also associated with an increased concentration of cytokines (TNFa, IL1a, IL6, IFNg) and thyroid-stimulating hormone in the serum, pointing to a possible triangular relationship between immune system, vegetative nervous system, and emotional dysregulation.

LIMITATIONS

We used a plethysmographic device for the measurement of heartbeat instead of an electrocardiogram, and had a single time point only.

CONCLUSIONS

This data corroborate the idea that a disequilibrium of the vegetative nervous, especially if accompanied by a dysregulation system in immune function, can increase the risk for depression. Conversely, vagal stimulation and anti-inflammatory treatments may support the treatment with antidepressants.

The Association between Inflammatory Biomarkers and Cardiovascular Autonomic Dysfunction after Bacterial Infection

Heart rate variability (HRV) is a known measure of cardiac autonomic function. A cardiovascular autonomic dysfunction (CAD), measured as changes in HRV, is usually presented after an infectious process. The aim of the present study is to assess the association between serum inflammatory markers and CAD. For this purpose, 50 volunteers (13 of them recovering from an infection) were recruited and followed-up for 6 weeks. Their serum inflammatory biomarkers (CRP, IL1, IL4, IL6, IL10, and TNFalpha) were quantified throughout those weeks, along with their HRV resting, in response to the Valsalva maneuver, metronome breathing, standing and sustained handgrip. The correlation of within-subject changes in both HRV and inflammatory biomarkers was assessed to evaluate the concurrent changes. An inverse within-subject correlation was found between CRP and HRV in response to the Valsalva maneuver (rho (95% CI): −0.517 (−0.877 to −0.001); p = 0.032) and HRV standing (rho (95% CI): −0.490 (−0.943 to −0.036); p = 0.034). At the beginning, increased values of CRP are found along with reduced levels of HRV. Then, the CRP was reduced, accompanied by an improvement (increase) in HRV. These results suggest that CRP is a potential marker of CAD. Whether it is the cause, the consequence or a risk indicator non-causally associated is still to be determined.

Transcutaneous Cervical Vagal Nerve Stimulation in Patients with Posttraumatic Stress Disorder (PTSD): A Pilot Study of Effects on PTSD Symptoms and Interleukin-6 Response to Stress

BACKGROUND

Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory and sympathetic function, responsible for maintenance of symptoms. Treatment options including medications and psychotherapies have limitations. We previously showed that transcutaneous Vagus Nerve Stimulation (tcVNS) blocks inflammatory (interleukin (IL)-6) responses to stress in PTSD. The purpose of this study was to assess the effects of tcVNS on PTSD symptoms and inflammatory responses to stress.

METHODS

Twenty patients with PTSD were randomized to double blind active tcVNS (N=9) or sham (N=11) stimulation in conjunction with exposure to personalized traumatic scripts immediately followed by active or sham tcVNS and measurement of IL-6 and other biomarkers of inflammation. Patients then self administered active or sham tcVNS twice daily for three months. PTSD symptoms were measured with the PTSD Checklist (PCL) and the Clinician Administered PTSD Scale (CAPS), clinical improvement with the Clinical Global Index (CGI) and anxiety with the Hamilton Anxiety Scale (Ham-A) at baseline and one-month intervals followed by a repeat of measurement of biomarkers with traumatic scripts. After three months patients self treated with twice daily open label active tcVNS for another three months followed by assessment with the CGI.

RESULTS

Traumatic scripts increased IL-6 in PTSD patients, an effect that was blocked by tcVNS (p<.05). Active tcVNS treatment for three months resulted in a 31% greater reduction in PTSD symptoms compared to sham treatment as measured by the PCL (p=0.013) as well as hyperarousal symptoms and somatic anxiety measured with the Ham-A p<0.05). IL-6 increased from baseline in sham but not tcVNS. Open label tcVNS resulted in improvements measured with the CGI compared to the sham treatment period p<0.05).

CONCLUSIONS

These preliminary results suggest that tcVNS reduces inflammatory responses to stress, which may in part underlie beneficial effects on PTSD symptoms.

Heart Rate Variability and Inflammatory Stress Response in Young African American Men: Implications for Cardiovascular Risk

Background: African American men have a disproportionately higher incidence of and suffer greater severity and earlier death from cardiovascular disease (CVD). A common feature of many diseases, which disproportionately afflict disadvantaged African Americans, is inflammation. In particular, inflammation plays a decisive role in the pathogenesis of CVD in that persistent inflammation contributes to plaque evolution and destabilization. Adverse childhood experiences increase the risk for adult inflammatory based disease, particularly cardiovascular disease. This inflammatory burden becomes evident during stressful events and may be related to alterations in autonomic nervous system (ANS) activity. We previously reported that African American men who experienced childhood adversity exhibited a greater inflammatory (IL-6) response to acute stress challenge (Trier Social Stress Test - TSST). The purpose of this study was to determine whether altered ANS activity, as measured by heart rate variability (HRV), contributes to a greater proinflammatory response to stress in those exposed to childhood adversity. Methods: Thirty-four African American adult males underwent the TSST while instrumented with Holter monitors to record continuous heart rate for HRV determination. HRV was calculated as the low frequency (LF) to high frequency (HF) heart rate ratio (LF/HF), with higher LF/HF ratios corresponding to higher sympathetic vs. parasympathetic activity. Salivary samples were collected pre- and post-TSST to measure the proinflammatory cytokine IL-6. Childhood adversity was assessed by the Childhood Trauma Questionnaire. Results: Hierarchical linear modeling demonstrated that higher levels of physical abuse were related to a steeper rise in LF/HF ratio during the TSST. Further, a higher LF/HF ratio, in combination with greater exposure to emotional and physical abuse was associated with a greater IL-6 response to the TSST. Conclusions: These findings suggest that adverse childhood experiences associate with an adult phenotype characterized by an altered ANS response to stress as well as a greater proinflammatory (IL-6) response to an acute stressor. Elevations in salivary inflammatory markers have been associated with increased CVD risk. In conclusion, these findings suggest a role for the ANS in the underlying neuro-biological processes whereby childhood adversity predisposes to a more intense inflammatory response to stressful challenge during adulthood.

Resting parasympathetic nervous system activity is associated with greater antiviral gene expression

Parasympathetic nervous system activity can downregulate inflammation, but it remains unclear how parasympathetic nervous system activity relates to antiviral activity. The present study examined associations between parasympathetic nervous system activity and cellular antiviral gene regulation in 90 adolescents (M_age = 16.28, SD = 0.73; 51.1% female) who provided blood samples and measures of cardiac respiratory sinus arrhythmia (RSA), twice, five weeks apart. Using a multilevel analytic framework, we found that higher RSA (an indicator of higher parasympathetic nervous system activity)-both at rest and during paced breathing-was associated with higher expression of Type I interferon (IFN) response genes in circulating leukocytes, even after adjusting for demographic and biological covariates. RSA was not associated with a parallel measure of inflammatory gene expression. These results identify a previously unrecognized immunoregulatory aspect of autonomic nervous system function and highlight a potential biological pathway by which parasympathetic nervous system activity may relate to health.

Nerve-macrophage interactions in cardiovascular disease

The heart is highly innervated by autonomic neurons, and dynamic autonomic regulation of the heart and blood vessels is essential for animals to carry out the normal activities of life. Cardiovascular diseases, including heart failure and myocardial infarction, are often characterized in part by an imbalance in autonomic nervous system activation, with excess sympathetic and diminished parasympathetic activation. Notably, however, this is often accompanied by chronic inflammation within the cardiovascular tissues, which suggests there are interactions between autonomic dysregulation and inflammation. Recent studies have been unraveling the mechanistic links between autonomic nerves and immune cells within cardiovascular disease. The autonomic nervous system and immune system also act in concert to coordinate the actions of multiple organs that not only maintain homeostasis but also likely play key roles in disease-disease interactions, such as cardiorenal syndrome and multimorbidity. In this review, we summarize the physiological and pathological interactions between autonomic nerves and macrophages in the context of cardiovascular disease.

Heart Rate Variability and Circulating Inflammatory Markers in Midlife

Theoretical perspectives and empirical evidence suggest that the parasympathetic nervous system engages in active monitoring and moderating of inflammatory processes. A clearer understanding of the bidirectional communication between the parasympathetic nervous system and the immune system could lead to novel clinical interventions for inflammatory illnesses. The current study used a large (N ​= ​836) nationally representative sample of adults in the United States to investigate the associations between resting parasympathetic modulation of the heart, indexed through both high frequency heart rate variability (HF-HRV) and low frequency heart rate variability (LF-HRV), and six circulating markers of inflammation. Statistical analyses revealed robust inverse associations of HF-HRV with interleukin-6 (IL6), C-reactive protein (CRP), and fibrinogen, with or without covariate adjustment. Similar inverse associations were observed between LF-HRV and IL6 and CRP. No significant associations were observed between HRV and either inflammatory adhesion molecules (E-selectin, intracellular adhesion molecule-1) or soluble IL6 receptor. Results are consistent with the cholinergic anti-inflammatory pathway and suggest that parasympathetic modulation of inflammation through the vagus nerve may act on specific inflammatory molecules more than others.

Microbiota and Metabolites as Factors Influencing Blood Pressure Regulation

The study of microbes has rapidly expanded in recent years due to a surge in our understanding that humans host a plethora of commensal microbes, which reside in their bodies and depending upon their composition, contribute to either normal physiology or pathophysiology. This article provides a general foundation for learning about host-commensal microbial interactions as an emerging area of research. The article is divided into two sections. The first section is dedicated to introducing commensal microbiota and its known effects on the host. The second section is on metabolites, which are biochemicals that the host and the microbes use for bi-directional communication with each other. Together, the sections review what is known about how microbes interact with the host to impact cardiovascular physiology, especially blood pressure regulation. © 2021 American Physiological Society. Compr Physiol 11:1731-1757, 2021.

Coherence Between Feelings and Heart Rate: Links to Early Adversity and Responses to Stress

Past research suggests that higher coherence between feelings and physiology under stress may confer regulatory advantages. Research and theory also suggest that higher resting vagal tone (rVT) may promote more adaptive responses to stress. The present study examines the roles of response system coherence (RSC; defined as the within-individual covariation between feelings and heart rate over time) and rVT in mediating the links between childhood adversity and later-life responses to acute stressors. Using data from 279 adults from the Second Generation Study of the Harvard Study of Adult Development who completed stressful public speaking and mental arithmetic tasks, we find that individuals who report more childhood adversity have lower RSC, but not lower rVT. We further find that lower RSC mediates the association between adversity and slower cardiovascular recovery. Higher rVT in the present study is linked to less intense cardiovascular reactivity to stress, but not to quicker recovery or to the subjective experience of negative affect after the stressful tasks. Additional analyses indicate links between RSC and mindfulness and replicate previous findings connecting RSC to emotion regulation and well-being outcomes. Taken together, these findings are consistent with the idea that uncoupling between physiological and emotional streams of affective experiences may be one of the mechanisms connecting early adversity to later-life affective responses. These findings also provide evidence that RSC and rVT are associated with distinct aspects of self-regulation under stress.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s42761-020-00027-5.

Positive affect and peripheral inflammatory markers among adults: A narrative review

BACKGROUND

Previous research suggests that positive affect (PA) may promote health and longevity and that one potential mechanism involves inflammation. However, it remains unclear to what extent PA is associated with specific inflammatory markers and whether such associations are driven by main effects of PA and/or due to PA operating as a stress-buffer.

METHODS

The present narrative review incorporates studies (N = 28) that have examined the association between PA and peripheral inflammatory markers obtained using venous puncture or dried blood spots. We separate results by whether the study tested direct effects or stress-buffering, and by type of inflammatory marker [including C-reactive protein (CRP), and proinflammatory and anti-inflammatory cytokines], also paying close attention to type of PA assessment (state, aggregated state, or retrospective, the latter involving recall over one to two weeks), and study design (cross-sectional, longitudinal, and experimental).

RESULTS

Limited evidence suggests that studies were more supportive of a stress-buffering association, compared to a relatively direct association. When significant direct associations were observed, results suggested that studies using measures of state/aggregated PA exhibited more consistent associations with inflammatory markers than studies using retrospective PA. When significant, higher PA tended to be associated with lower pro- and anti-inflammatory markers, suggestive of lower overall inflammatory load.

DISCUSSION

Recommendations for the field and future research are discussed, including the value of utilizing state/aggregated PA measures and of examining stress-buffering mechanisms.

Heart Rate Variability in Women with Systemic Lupus Erythematosus: Association with Health-Related Parameters and Effects of Aerobic Exercise

Abnormal heart rate variability (HRV) has been observed in patients with systemic lupus erythematosus (SLE). In a combined cross-sectional and interventional study approach, we investigated the association of HRV with inflammation and oxidative stress markers, patient-reported outcomes, and the effect of 12 weeks of aerobic exercise in HRV. Fifty-five women with SLE (mean age 43.5 ± 14.0 years) were assigned to either aerobic exercise (n = 26) or usual care (n = 29) in a non-randomized trial. HRV was assessed using a heart rate monitor during 10 min, inflammatory and oxidative stress markers were obtained, psychological stress (Perceived Stress Scale), sleep quality (Pittsburg Sleep Quality Index), fatigue (Multidimensional Fatigue Inventory), depressive symptoms (Beck Depression Inventory), and quality of life (36-item Short-Form Health Survey) were also assessed. Low frequency to high frequency power (LFHF) ratio was associated with physical fatigue (p = 0.019). Sample entropy was inversely associated with high-sensitivity C-reactive protein (p = 0.014) and myeloperoxidase (p = 0.007). There were no significant between-group differences in the changes in HRV derived parameters after the exercise intervention. High-sensitivity C-reactive protein and myeloperoxidase were negatively related to sample entropy and physical fatigue was positively related to LFHF ratio. However, an exercise intervention of 12 weeks of aerobic training did not produce any changes in HRV derived parameters in women with SLE in comparison to a control group.

Transcutaneous vagal nerve stimulation blocks stress-induced activation of Interleukin-6 and interferon-γ in posttraumatic stress disorder: A double-blind, randomized, sham-controlled trial

Posttraumatic stress disorder (PTSD) is a highly disabling condition associated with alterations in multiple neurobiological systems, including increases in inflammatory function. Vagus nerve stimulation (VNS) decreases inflammation, however few studies have examined the effects of non-invasive VNS on physiology in human subjects, and no studies in patients with PTSD. The purpose of this study was to assess the effects of transcutaneous cervical VNS (tcVNS) on inflammatory responses to stress. Thirty subjects with a history of exposure to traumatic stress with (N ​= ​10) and without (N ​= ​20) PTSD underwent exposure to stressful tasks immediately followed by active or sham tcVNS and measurement of multiple biomarkers of inflammation (interleukin-(IL)-6, IL-2, IL-1β, Tumor Necrosis Factor alpha (TNFα) and Interferon gamma (IFNγ) over multiple time points. Stressful tasks included exposure to personalized scripts of traumatic events on day 1, and public speech and mental arithmetic (Mental Stress) tasks on days 2 and 3. Traumatic scripts were associated with a pattern of subjective anger measured with Visual Analogue Scales and increased IL-6 and IFNγ in PTSD patients that was blocked by tcVNS (p ​< ​.05). Traumatic stress had minimal effects on these biomarkers in non-PTSD subjects and there was no difference between tcVNS or sham. No significant differences were seen between groups in IL-2, IL-1β, or TNFα. These results demonstrate that tcVNS blocks behavioral and inflammatory responses to stress reminders in PTSD.

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.

Circulating Inflammatory Markers Are Inversely Associated with Heart Rate Variability Measures in Type 1 Diabetes

Introduction

A neuroimmune communication exists, and compelling evidence suggests that diabetic neuropathy and systemic inflammation are linked. Our aims were (1) to investigate biomarkers of the ongoing inflammation processes including cytokines, adhesion molecules, and chemokines and (2) to associate the findings with cardiovascular autonomic neuropathy in type 1 diabetes by measuring heart rate variability and cardiac vagal tone.

Materials and Methods

We included 104 adults with type 1 diabetes. Heart rate variability, time domain, and frequency domains were calculated from a 24-hour Holter electrocardiogram, while cardiac vagal tone was determined from a 5-minute electrocardiogram. Cytokines (interleukin- (IL-) 1α, IL-4, IL-12p70, IL-13, IL-17, and tumor necrosis factor- (TNF-) α), adhesion molecules (E-selectin, P-selectin, and intercellular adhesion molecule- (ICAM-) 1), and chemokines (chemokine (C-C motif) ligand (CCL)2, CCL3, CCL4, and C-X-C motif chemokine (CXCL)10) were assessed using a Luminex multiplexing technology. Associations between concentrations of inflammatory biomarkers and continuous variables of heart rate variability and cardiac vagal tone were estimated using multivariable linear regression adjusting for age, sex, disease duration, and smoking.

Results

Participants with the presence of cardiovascular autonomic neuropathy had higher systemic levels of IL-1α, IL-4, CCL2, and E-selectin than those without cardiovascular autonomic neuropathy. IL-1α, IL-4, IL-12, TNF-α, and E-selectin were inversely associated with both sympathetic and parasympathetic heart rate variability measures (p > 0.01). Discussion. Our results show that several pro- and anti-inflammatory factors, believed to be involved in the progression of diabetic polyneuropathy, are associated with cardiovascular autonomic neuropathy, suggesting that these factors may also contribute to the pathogenesis of cardiovascular autonomic neuropathy. Our findings emphasize the importance of the neuroimmune regulatory system in the pathogenesis of neuropathy in type 1 diabetes.

Role of the parasympathetic nervous system in cancer initiation and progression

The nervous system plays an important role in cancer initiation and progression. Accumulated evidences clearly show that the sympathetic nervous system exerts stimulatory effects on carcinogenesis and cancer growth. However, the role of the parasympathetic nervous system in cancer has been much less elucidated. Whereas retrospective studies in vagotomized patients and experiments employing vagotomized animals indicate the parasympathetic nervous system has an inhibitory effect on cancer, clinical studies in patients with prostate cancer indicate it has stimulatory effects. Therefore, the aim of this paper is a critical evaluation of the available data related to the role of the parasympathetic nervous system in cancer.

Harsh parenting and youth systemic inflammation: Modulation by the autonomic nervous system

OBJECTIVE

The present study aimed to test the role of the autonomic nervous system (ANS) in modulating the impact of family stress induced by harsh parenting on youths' inflammation. First, we examined the direct effect of severity of adverse parenting behaviors on two serum biomarkers of systemic inflammation (C-reactive protein and interleukin-6) among youth. Second, we tested the moderating role of ANS reactivity in response to laboratory-induced stress in the association between harsh parenting and inflammation among these youth.

METHOD

The sample included 101 low-income children (75.2% African American) between 9 and 12 years of age (M_age = 10.9; SD_age = 1.2) who participated in a conflict task with their primary caregiver in a laboratory setting. Heart rate variability reactivity (HRV-R), skin conductance level reactivity (SCL-R), and preejection period reactivity (PEPr-R) were used to index parasympathetic and sympathetic nervous system reactivity. Markers of low-grade inflammation (C-reactive protein and interleukin-6) were obtained from serum.

RESULTS

After adjusting for confounding variables, ANS activity moderated the associations between family stress and systemic inflammation. Specifically, elevated HRV-R buffered the effect of family stress on youths' inflammation, whereas elevated PEPr-R and SCL-R exacerbated the effect.

CONCLUSION

These findings show that self-regulatory capacity and threat sensitivity, as indicated by ANS function, may have an impact on the associations between family stress and systemic inflammation. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Association Between Systemic Inflammation, Carotid Arteriosclerosis, and Autonomic Dysfunction

Systemic inflammation is associated with arteriosclerotic disease progression and worse stroke outcome in patients with carotid arteriosclerotic disease. We hypothesize that systemic inflammation is mediated by impaired carotid baroreceptor and chemoreceptor function induced by carotid arteriosclerosis rather than by the generalized inflammatory arteriosclerotic process.Heart rate variability (HRV), serum levels of inflammatory markers, demographic and life style factors, and concomitant diseases with potential impact on systemic inflammation were determined in 105 patients with asymptomatic carotid stenosis of varying degree. Multivariate linear regression analyses were performed to ascertain independent determinants of carotid stenosis severity, autonomic function, and inflammation.Systemic inflammation (C-reactive protein, beta = .255; P = .014), age (beta = .232; P < .008), and arterial hypertension (beta = .206; P = .032) were associated with carotid stenosis severity. Only carotid stenosis severity and not generalized arteriosclerotic disease, concomitant diseases (arterial hypertension, diabetes mellitus, dyslipidemia, hypothyroidism), life style factors (smoking, obesity), or age was associated with a reduction in vagal tone (HRV HF band power beta = - .193; P < 0.049). Systemic inflammation was related to a reduction in vagal tone (HRV HF band power, beta = - .214; P = .031), and not to generalized arteriosclerotic disease, concomitant diseases (arterial hypertension, diabetes mellitus, dyslipidemia), life style factors (smoking, obesity), and age.In conclusion, systemic inflammation is associated with carotid rather than with generalized arteriosclerotic disease. The association between systemic inflammation and carotid arteriosclerosis is mediated by a reduction in vagal tone which indicates a major role of carotid arteriosclerosis-mediated autonomic dysfunction in the pathogenesis of systemic inflammation in arteriosclerotic disease.

Associations of immunometabolic risk factors with symptoms of depression and anxiety: The role of cardiac vagal activity

OBJECTIVES

This study examined 1) the cross-sectional relationships between symptoms of depression/anxiety and immunometabolic risk factors, and 2) whether these relationships might be explained in part by cardiac vagal activity.

METHODS

Data were drawn from the Adult Health and Behavior registries (n = 1785), comprised of community dwelling adults (52.8% women, aged 30-54). Depressive symptoms were measured with the Center for Epidemiological Studies Depression Scale (CES-D) and the Beck Depression Inventory-II (BDI-II), and anxious symptoms with the Trait Anxiety scale of the State-Trait Anxiety Inventory (STAI-T). Immunometabolic risk factors included fasting levels of triglycerides, high-density lipoproteins, glucose, and insulin, as well as blood pressure, waist circumference, body mass index, C-reactive protein, and interleukin-6. Measures of cardiac autonomic activity were high- and low-frequency indicators of heart rate variability (HRV), standard deviation of normal-to-normal R-R intervals, and the mean of absolute and successive differences in R-R intervals.

RESULTS

Higher BDI-II scores, in contrast to CES-D and STAI-T scores, were associated with increased immunometabolic risk and decreased HRV, especially HRV likely reflecting cardiac vagal activity. Decreased HRV was also associated with increased immunometabolic risk. Structural equation models indicated that BDI-II scores may relate to immunometabolic risk via cardiac vagal activity (indirect effect: β = .012, p = .046) or to vagal activity via immunometabolic risk (indirect effect: β = -.015, p = .021).

CONCLUSIONS

Depressive symptoms, as measured by the BDI-II, but not anxious symptoms, were related to elevated levels of immunometabolic risk factors and low cardiac vagal activity. The latter may exhibit bidirectional influences on one another in a meditational framework. Future longitudinal, intervention, an nonhuman animal work is needed to elucidate the precise and mechanistic pathways linking depressive symptoms to immune, metabolic, and autonomic parameters of physiology that predispose to cardiovascular disease risk.

Threats to Belonging, Immune Function, and Eating Behavior: an Examination of Sex and Gender Differences

PURPOSE OF REVIEW

The first goal of this review is to discuss the evidence linking belonging threats to immune function and food intake. The second goal is to evaluate whether the links among belonging threats, immune function, and eating behavior differ based on gender.

RECENT FINDINGS

Threats to belonging are linked to elevated herpesvirus antibody titers, dysregulated appetite-relevant hormones, and increased food consumption. Furthermore, these relationships are largely consistent for both men and women. Threats to belonging are also linked to elevated inflammation. However, some studies showed that these effects were stronger among women, others demonstrated that they were stronger among men, and others determined that the links were consistent for men and women. Understanding why belonging threats are inconsistently linked to inflammation across men and women is an important next step. We conclude the review with four concrete recommendations for researchers studying belonging threats, immune function, and eating behavior.

Vagal-immune interactions involved in cholinergic anti-inflammatory pathway

Inflammation and other immune responses are involved in the variety of diseases and disorders. The acute response to endotoxemia includes activation of innate immune mechanisms as well as changes in autonomic nervous activity. The autonomic nervous system and the inflammatory response are intimately linked and sympathetic and vagal nerves are thought to have anti-inflammation functions. The basic functional circuit between vagus nerve and inflammatory response was identified and the neuroimmunomodulation loop was called cholinergic anti-inflammatory pathway. Unique function of vagus nerve in the anti-inflammatory reflex arc was found in many experimental and pre-clinical studies. They brought evidence on the cholinergic signaling interacting with systemic and local inflammation, particularly suppressing immune cells function. Pharmacological/electrical modulation of vagal activity suppressed TNF-alpha and other proinflammatory cytokines production and had beneficial therapeutic effects. Many questions related to mapping, linking and targeting of vagal-immune interactions have been elucidated and brought understanding of its basic physiology and provided the initial support for development of Tracey´s inflammatory reflex. This review summarizes and critically assesses the current knowledge defining cholinergic anti-inflammatory pathway with main focus on studies employing an experimental approach and emphasizes the potential of modulation of vagally-mediated anti-inflammatory pathway in the treatment strategies.

During stress, heart rate variability moderates the impact of childhood adversity in women with breast cancer

Childhood adversity has long-lasting neuro-biological effects that can manifest as exaggerated stress responsivity to environmental challenge. These manifestations include a dysregulated hypothalamic-pituitary-adrenocortical (HPA) axis as well as increased levels of inflammatory mediators in response to stress. In this investigation, vagal parasympathetic activity was assessed for its capacity to moderate the relationship between childhood adversity and stress responsivity (cortisol and inflammation) during an acute laboratory challenge (Trier Social Stress Test-TSST). Thirty women recently diagnosed with breast cancer underwent the TSST during which their heart rate was recorded and saliva samples collected for measurement of cortisol and the proinflammatory cytokine, IL-6. Vagal activity during the TSST was calculated as the high-frequency (HF) component of heart rate variability (HRV). Vagal activity during the TSST moderated the effect of childhood adversity on both the cortisol and the IL-6 response. Women who had lower vagal stress-reactivity during the TSST and reported greater childhood adversity showed a larger rise in cortisol and IL-6 when compared to women with lower childhood adversity. The findings demonstrate that women with exposure to childhood adversity and low vagal stress-reactivity (reduced parasympathetic activity) exhibit an elevated stress response characterized by greater cortisol and proinflammatory cytokine release. Inflammatory burden and HPA dysregulation subsequent to stress may impair cancer control.

Cytokine Levels in Panic Disorder: Evidence for a Dose-Response Relationship

OBJECTIVE

Several studies have investigated possible biological correlates of mental disorders. Although some studies have consistently reported elevated levels of serum inflammatory markers in depression, very few have evaluated cytokine levels in patients with lifetime panic disorder (PD).

METHODS

Seventy-eight adults (75% women) from an anxiety disorders outpatient unit were categorized according to their PD status: current or in remission. Serum levels of interleukin (IL)-6, tumor necrosis factor α, and IL-10 were evaluated using flow cytometry with enhanced sensitivity flex sets. Data on clinical comorbidity, lipid profile, fasting blood glucose, C-reactive protein, and PD severity were also obtained.

RESULTS

Significantly higher mean levels of serum IL-6 (0.83 vs 0.60 pg/mL [95% confidence interval {CI}for the log-transformed mean difference, -0.41 to -0.57], p = .008) but not of tumor necrosis factor-α (0.18 vs 0.14 pg/mL [95% CI, -1.12 to 0.11]; p = 0.53) or IL-10 (0.21 vs 0.26 [95% CI, -0.20 to 0.44]; p = 0.16), were associated with current PD compared to remitted PD. Higher Panic Disorder Severity Scale (standardized β = 0.36; p = .013), body mass index (standardized β = 0.53, p < .001) and fasting blood glucose 5.6 mmol/L or greater (standardized β = 0.23, p = .038) were significantly associated with higher levels of IL-6 in the multivariate linear regression model.

CONCLUSIONS

Our findings support a proinflammatory state in patients with current PD that is independent of possible confounders. Although there are important implications of these findings, replication is required.

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.

Cognición, respuesta electroencefalográfica y su relación con la variabilidad de la frecuencia cardíaca

Introducción. La corteza cerebral frontal tiene una mayor actividad teta durante procesos cognitivos de observación y aprendizaje.Objetivo. Establecer la relación entre actividad electroencefalográfica orbitofrontal y sistema nervioso autónomo en procesos cognitivos.Materiales y métodos. 20 hombres y 19 mujeres con edad promedio de 21.2 (±2.32) años fueron evaluados mediante electroencefalografía (EGG) FP1-T3, FP2-T4 y electrocardiografía (EKG, del alemán elektrokardiogramm) para determinar frecuencia cardíaca (HR, del inglés heart rate) y variabilidad de la frecuencia cardíaca (HRV, del inglés heart rate variability). La evaluación tuvo cinco fases: reposo, observación, memoria, concentración y juego. Las señales de EGG y EKG fueron analizadas en el dominio de la frecuencia usando la transformada rápida de Fourier (FFT, del inglés fast Fourier transform). Las diferencias por etapa entre las variables se establecieron con el uso de ANOVA de dos vías.Resultados. Comparado con el reposo, se observó en todas las fases incremento de la actividad teta del EGG (p<0.01), aumento en la baja frecuencia LF (p<0.01) y la HR (p<0.01) y disminución de la alta frecuencia HF (p<0.01). Además, hubo una correlación inversa entre la actividad teta y la potencia de HF (r=-0.86).Conclusiones. Los datos mostraron una reducción de la actividad parasimpática y un aumento de la actividad simpática asociado a actividad teta de la corteza orbitofrontal, mediante una conexión con el núcleo central de la amígdala.

Psychophysiological correlates of systemic inflammation in black and white men

Inflammation plays a critical role in the pathophysiology of cardiovascular disease (CVD) and levels of circulating inflammatory markers are associated with future CVD risk. However, the physiological mechanisms that control systemic levels of circulating inflammatory markers are not well understood. Here, we explore possible autonomic nervous system mechanisms by testing whether resting and stressor-evoked cardiovascular responses are associated with two markers of systemic inflammation: interleukin (IL)-6 and C-reactive protein (CRP). Subjects were 159 black and 129 white men (M=33.0years) who completed a laboratory protocol including an anger recall speech task. Electrocardiography and impedance cardiography data were collected during a resting baseline, the speech task, and a final recovery period. Hierarchical regressions tested whether resting or stressor-evoked levels of heart rate (HR), high-frequency heart rate variability (HF-HRV), pre-ejection period (PEP), and pulse transit time (PTT) were associated with CRP or IL-6. Higher resting HR was associated with higher CRP (β=0.19, p=0.003) and IL-6 (β=0.13, p<0.05). Similarly, shorter resting PTT was associated with higher CRP (β=-0.21, p<0.001) and IL-6 (β=-0.14, p=0.02). In addition, greater stressor-evoked decreases in HF-HRV were associated with higher CRP (β=-0.14, p=0.01). Associations were independent of age, race, body mass index (BMI), smoking behavior, and socioeconomic status. Resting HF-HRV and PEP were also associated with CRP and IL-6, but associations were not significant after controlling for BMI and smoking behavior. These findings indicate that resting HR and PTT, as well stressor-evoked HF-HRV reactivity, are associated with systemic inflammation. Our results suggest that both tonic and stressor-evoked sympathetic and parasympathetic nervous system activity may contribute to regulation of systemic inflammation.

Leukocyte Populations are Associated with Heart Rate Variability After a Triathlon

The purpose of this study was to analyze cellular immune components and their association with heart rate variability in triathlon athletes. Twelve athletes were included (age 36.41 ± 5.57 years, body mass 81.84 ± 10.97 kg) and blood samples were taken one week before, immediately, at 2 and 48 hours, and one week after competition. Total lymphocytes and their subpopulations, neutrophils, basophils, eosinophils and monocytes were analyzed. At the same time, heart rate variability was recorded for 30 minutes using Polar Team2®. A significant difference between lymphocyte subpopulations and heart rate variability was found in the different study periods. A positive correlation was found between total lymphocytes and rMSSD (r = .736, p <0.05), CD3+ and rMSSD (r = .785, p <0.05), and CD4+ and rMSSD (r = .795, p < 0.05) at the end of the competition. After one week of competition, a negative correlation was found between eosinophils and MRR, SDNN, pNN50, and rMSSD (p <0.01); and basophils and MRR, SDNN, pNN50, and rMSSD (p <0.01); while a positive correlation was found between CD19+ (B cells) and pNN50 (r = .678, p <0.05). Our results suggest that it is possible to predict the effect of training with regard to the athlete's performance.

Vagal Modulation of the Inflammatory Response in Sepsis

The vagus nerve can sense peripheral inflammation and transmit action potentials from the periphery to the brainstem. Vagal afferent signaling is integrated in the brainstem, and efferent vagus nerves carry outbound signals that terminate in spleen and other organs. Stimulation of efferent vagus nerve leads to the release of acetylcholine in these organs. In turn, acetylcholine interacts with members of the nicotinic acetylcholine receptor (nAChR) family, particularly with the alpha7 nicotinic acetylcholine receptor (α7nAChR), which is expressed by macrophages and other cytokine-producing cells. Ultimately, the production of proinflammatory cytokines is markedly inhibited. This neuroimmune communication is termed "the inflammatory reflex". The uncontrolled inflammation as a result from sepsis can lead to multiple organ failure, and even death. Experimental data show that regulation of the inflammatory reflex appears to be a useful interventional strategy for septic response. Herein, we review recent advances in the understanding of the inflammatory reflex and discuss potential therapeutics that vagal modulation of the immune system for the treatment of severe sepsis and septic shock.

The Psychosocial Context of Financial Stress: Implications for Inflammation and Psychological Health

OBJECTIVE

Psychological distress may contribute to chronic activation of acute-phase inflammation. The current study investigated how financial stressors influence psychosocial functioning and inflammation. This study examined a) the direct relations between financial stress and inflammation; b) whether the relationships between financial stress and inflammation are mediated in part by negative interpersonal events, psychological distress, and psychological well-being; and c) whether social standing in one's community moderates the relations between financial stress and psychological distress, psychological well-being, and markers of inflammation (interleukin-6 [IL-6] and C-reactive protein).

METHODS

Stressful financial and interpersonal events over the previous year, perceived social status, indices of psychological well-being and distress, and levels of IL-6 and C-reactive protein were assessed in a community sample of 680 middle-aged adults (ages 40-65 years).

RESULTS

Structural equation modeling analyses revealed significant relations among financial stress, interpersonal stress, and psychological distress and well-being, and complex relationships between these variables and inflammatory markers. Psychological well-being mediated the association between financial stress and IL-6 ([mediation] ab = 0.012, standard error [SE] = 0.006, p = .048). Furthermore, individuals with higher perceived social standing within their communities exhibited a stronger relation between negative financial events and both interpersonal stressors (interaction B = 0.067, SE = 0.017, p < .001) and C-reactive protein (interaction B = 0.051, SE = 0.026, p = .050).

CONCLUSIONS

Financial stress demonstrates complex relations with inflammation, due partly to psychological well-being and social perceptions. Findings are discussed with regard to the social context of stress and physiological factors pertinent to stress adaptation and inflammation.

Cholinergic Pathway Suppresses Pulmonary Innate Immunity Facilitating Pneumonia After Stroke

BACKGROUND AND PURPOSE

Temporary immunosuppression has been identified as a major risk factor for the development of pneumonia after acute central nervous system injury. Although overactivation of the sympathetic nervous system was previously shown to mediate suppression of systemic cellular immune responses after stroke, the role of the parasympathetic cholinergic anti-inflammatory pathway in the antibacterial defense in lung remains largely elusive.

METHODS

The middle cerebral artery occlusion model in mice was used to examine the influence of the parasympathetic nervous system on poststroke immunosuppression. We used heart rate variability measurement by telemetry, vagotomy, α7 nicotinic acetylcholine receptor-deficient mice, and parasympathomimetics (nicotine, PNU282987) to measure and modulate parasympathetic activity.

RESULTS

Here, we demonstrate a rapidly increased parasympathetic activity in mice after experimental stroke. Inhibition of cholinergic signaling by either vagotomy or by using α7 nicotinic acetylcholine receptor-deficient mice reversed pulmonary immune hyporesponsiveness and prevented pneumonia after stroke. In vivo and ex vivo studies on the role of α7 nicotinic acetylcholine receptor on different lung cells using bone marrow chimeric mice and isolated primary cells indicated that not only macrophages but also alveolar epithelial cells are a major cellular target of cholinergic anti-inflammatory signaling in the lung.

CONCLUSIONS

Thus, cholinergic pathways play a pivotal role in the development of pulmonary infections after acute central nervous system injury.

Differential Patterns and Determinants of Cardiac Autonomic Nerve Dysfunction during Endotoxemia and Oral Fat Load in Humans

The autonomic nervous system (ANS) plays an important role in regulating the metabolic homeostasis and controlling immune function. ANS alterations can be detected by reduced heart rate variability (HRV) in conditions like diabetes and sepsis. We determined the effects of experimental conditions mimicking inflammation and hyperlipidemia on HRV and heart rate (HR) in relation to the immune, metabolic, and hormonal responses resulting from these interventions. Sixteen lean healthy subjects received intravenous (i.v.) low-dose endotoxin (lipopolysaccharide [LPS]), i.v. fat, oral fat, and i.v. glycerol (control) for 6 hours, during which immune, metabolic, hormonal, and five HRV parameters (pNN50, RMSSD, low-frequency (LF) and high-frequency (HF) power, and LF/HF ratio) were monitored and energy metabolism and insulin sensitivity (M-value) were assessed. LPS infusion induced an increase (AUC) in HR and LF/HF ratio and decline in pNN50 and RMSSD, while oral fat resulted in elevated HR and a transient (hours 1-2) decrease in pNN50, RMSSD, and HF power. During LPS infusion, ΔIL-1ra levels and ΔIL-1ra and ΔIL-1ß gene expression correlated positively with ΔLF/HF ratio and inversely with ΔRMSSD. During oral fat intake, ΔGLP-1 tended to correlate positively with ΔHR and inversely with ΔpNN50 and ΔRMSSD. Following LPS infusion, lipid oxidation correlated positively with HR and inversely with pNN50 and RMSSD, whereas HRV was not related to M-value. In conclusion, suppression of vagal tone and sympathetic predominance during endotoxemia are linked to anti-inflammatory processes and lipid oxidation but not to insulin resistance, while weaker HRV changes in relation to the GLP-1 response are noted during oral fat load.

Trajectories of internalizing symptoms across childhood: The roles of biological self-regulation and maternal psychopathology

Whether internalizing symptoms increase or remain at similar levels throughout childhood is currently not well understood. Moreover, the association between vagal regulation of cardiac activity and internalizing symptoms across childhood needs to be clarified. We used a multilevel conceptual framework to examine how children's vagal regulation of cardiac activity and mothers' internalizing symptoms were jointly associated with children's developmental trajectories of internalizing symptoms from ages 4 to 10 years old. Data came from 384 children who participated in an ongoing longitudinal study. Children and their mothers came to the research laboratory at ages 4, 5, 7, and 10. Mothers reported their children's and their own internalizing symptoms. Children's vagal regulation of cardiac activity was assessed during quiet baseline tasks and during challenge tasks. Multilevel models revealed that child internalizing symptoms increased from ages 4 to 10 years old, but only in females, and especially between ages 7 and 10. More vagal withdrawal in response to challenge was associated with more internalizing symptoms, particularly with more somatic symptoms. Associations between children's physiological regulation and internalizing symptoms differed by children's age, sex, and presence of maternal internalizing symptoms. Understanding associations between vagal regulation of cardiac activity and internalizing symptoms during childhood calls for fine-grained developmental analyses that take into account the heterogeneity of internalizing symptoms, as well as developmental phase, context, and gender.

Severe depressive symptoms are associated with elevated endothelin-1 in younger patients with acute coronary syndrome

OBJECTIVE

To explore the relationship of depressive symptom severity to circulating endothelin (ET)-1 in younger patients with acute coronary syndrome (ACS). Younger patients report greater depressive symptom severity, which predicts poorer post-ACS prognosis. The pathways linking depression to post-ACS prognosis require further elucidation. ET-1 is a potent endogenous vasoconstrictor which has been previously linked to adverse post-ACS outcomes.

METHODS

The sample (n=153) included males ≤ 50 years of age and females ≤ 55 years of age who participated in a larger study. Blood samples for ET-1 assessment were collected within 2-3h of ACS admission. Depressive symptoms were assessed with the Beck Depression Inventory (BDI) II within 2-5 days of admission. ET-1 was treated as a transformed continuous variable (ET-1T). BDI-II scores were classified into four categories using conventional thresholds demarcating mild, moderate, and severe levels of depressive symptoms. The relationship of classified BDI-II score to ET-1T was examined in simple and multivariable linear regression models.

RESULTS

Classified BDI-II score was related to ET-1T in both unadjusted (χ(2)=9.469, p=0.024) and multivariable (χ(2)=8.430, p=0.038) models, with ET-1T being significantly higher in patients with severe depressive symptoms than in those with mild and moderate depressive symptoms.

CONCLUSIONS

In this sample of younger post-ACS patients, severe depressive symptoms were associated with elevated ET-1. We acknowledge that the observed association could be eliminated by the inclusion of some unmeasured variable(s). Longitudinal research should examine whether ET-1 mediates the relationship of depressive symptoms to long-term post-ACS outcomes.

eNOS gene haplotype is indirectly associated with the recovery of cardiovascular autonomic modulation from exercise

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene decrease expression and activation of eNOS in vitro, which is associated with lower post-exercise increase in vasodilator reactivity in vivo. However, it is unknown whether such polymorphisms are associated with other eNOS-related phenotypes during recovery from exercise. Therefore, we investigated the impact of an eNOS haplotype containing polymorphic alleles at loci -786 and 894 on the recovery of cardiovascular autonomic function from exercise. Sedentary, non-obese, healthy subjects were enrolled [n = 107, age 32 ± 1 years (mean ± SEM)]. Resting autonomic modulation (heart rate variability, systolic blood pressure variability, and spontaneous baroreflex sensitivity) and vascular reactivity (forearm hyperemic response post-ischemia) were assessed at baseline, 10, 60, and 120 min after a maximal cardiopulmonary exercise test. Besides, autonomic function was assessed by heart rate recovery (HRR) immediately after peak exercise. Haplotype analysis showed that vagal modulation (i.e., HF n.u.) was significantly higher, combined sympathetic and vagal modulation (i.e., LF/HF) was significantly lower and total blood pressure variability was significantly lower post-exercise in a haplotype containing polymorphic alleles (H2) compared to a haplotype with wild type alleles (H1). HRR was similar between groups. Corroborating previous evidence, H2 had significantly lower post-exercise increase in vasodilator reactivity than H1. In conclusion, a haplotype containing polymorphic alleles at loci -786 and 894 had enhanced recovery of autonomic modulation from exercise, along with unchanged HRR, and attenuated vasodilator reactivity. Then, these results suggest an autonomic compensatory response of a direct deleterious effect of eNOS polymorphisms on the vascular function.

Resting high-frequency heart rate variability is related to resting brain perfusion

We examined the neural correlates of resting cardiac vagal activity in a sample of 432 participants (206 male; 61 African American; mean age 42 years). Pulsed arterial spin labeling was used to quantify whole brain and regional cerebral blood flow at rest. High-frequency heart rate variability (HF-HRV) was used to measure cardiac vagal activity at rest. The primary aim was to determine whether brain regions implicated in regulating cardiac vagal reactions were also related to cardiac vagal activity at rest, and whether these associations varied by sex or race. Brain areas previously related to vagal reactivity were related to resting HF-HRV. Directionality of relationships differed between overall and regional flows. Some relationships were only observed in women and African Americans. There appears to be communality between brain regions associated with task-induced vagal reactivity and those associated with resting cardiac vagal activity.

Usefulness of α7 nicotinic receptor messenger RNA levels in peripheral blood mononuclear cells as a marker for cholinergic antiinflammatory pathway activity in septic patients: results of a pilot study

BACKGROUND

Stimulation of the vagus nerve in the so-called cholinergic antiinflammatory pathway (CAP) attenuates systemic inflammation, improving survival in animal sepsis models via α7 nicotinic acetylcholine receptors on immunocompetent cells. Because the relevance of this regulatory pathway is unknown in human sepsis, this pilot study assessed whether the α7 gene expression level in septic patients' peripheral blood mononuclear cells (PBMC) might be used to assess CAP activity and clinical outcome.

METHODS

The PBMCs α7 messenger RNA levels were determined by real-time quantitative reverse-transcription polymerase chain reaction in 33 controls and 33 patients at enrollment and after their hospital discharge. Data were analyzed to find significant associations between α7 level, vagally mediated heart rate variability as an indirect reflection of CAP activity, serum concentrations of different inflammation markers, and clinical course.

RESULTS

Septic patients' α7 levels were significantly increased and returned to control values after recovery. These α7 levels correlated directly with the vagal heart input and inversely with the magnitude of the patient's inflammatory state, disease severity, and clinical outcome.

CONCLUSIONS

This study reveals that the PBMC α7 gene expression level is a clinically relevant marker for CAP activity in sepsis: the higher the α7 expression, the better the inflammation control and the prognosis.

Low heart rate variability and cancer-related fatigue in breast cancer survivors

Cancer-related fatigue is a common and often long lasting symptom for many breast cancer survivors. Fatigued survivors show evidence of elevated inflammation, but the physiological mechanisms driving inflammatory activity have not been determined. Alterations in the autonomic nervous system, and particularly parasympathetic nervous system activity, are a plausible, yet understudied contributor to cancer-related fatigue. The goal of this study was to replicate one previous study showing an association between lower parasympathetic activity and higher fatigue in breast cancer survivors (Fagundes et al., 2011), and to examine whether inflammation mediates this association. Study participants were drawn from two samples and included 84 women originally diagnosed with early stage breast cancer prior to age 50. Participants completed questionnaires, provided blood samples for determination of interleukin (IL)-6 and C-reactive protein (CRP), and underwent electrocardiography (ECG) assessment for evaluation of resting heart rate variability (HRV), a measure of parasympathetic activity. Results showed that lower HRV was associated with higher fatigue (p<.05), as predicted. In bivariate analyses, HRV was also correlated with circulating concentrations of IL-6 and CRP. However, path analyses did not support inflammation as a mediator of the association between HRV and fatigue; instead, associations among these variables appeared to be driven by age and BMI. These findings identify HRV as a potential contributor to cancer-related fatigue, but suggest that inflammation does not mediate this association in younger, healthy breast cancer survivors who are several years post-treatment. The autonomic nervous system merits additional attention in research on the etiology of cancer-related fatigue.

Fetal cholinergic anti-inflammatory pathway and necrotizing enterocolitis: the brain-gut connection begins in utero

Necrotizing enterocolitis (NEC) is an acute neonatal inflammatory disease that affects the intestine and may result in necrosis, systemic sepsis and multisystem organ failure. NEC affects 5-10% of all infants with birth weight ≤ 1500 g or gestational age less than 30 weeks. Chorioamnionitis (CA) is the main manifestation of pathological inflammation in the fetus and is strong associated with NEC. CA affects 20% of full-term pregnancies and upto 60% of preterm pregnancies and, notably, is often an occult finding. Intrauterine exposure to inflammatory stimuli may switch innate immunity cells such as macrophages to a reactive phenotype ("priming"). Confronted with renewed inflammatory stimuli during labour or postnatally, such sensitized cells can sustain a chronic or exaggerated production of proinflammatory cytokines associated with NEC (two-hit hypothesis). Via the cholinergic anti-inflammatory pathway, a neurally mediated innate anti-inflammatory mechanism, higher levels of vagal activity are associated with lower systemic levels of proinflammatory cytokines. This effect is mediated by the α7 subunit nicotinic acetylcholine receptor (α7nAChR) on macrophages. The gut is the most extensive organ innervated by the vagus nerve; it is also the primary site of innate immunity in the newborn. Here we review the mechanisms of possible neuroimmunological brain-gut interactions involved in the induction and control of antenatal intestinal inflammatory response and priming. We propose a neuroimmunological framework to (1) study the long-term effects of perinatal intestinal response to infection and (2) to uncover new targets for preventive and therapeutic intervention.

The vagal innervation of the gut and immune homeostasis

The central nervous system interacts dynamically with the immune system to modulate inflammation through humoral and neural pathways. Recently, in animal models of sepsis, the vagus nerve (VN) has been proposed to play a crucial role in the regulation of the immune response, also referred to as the cholinergic anti-inflammatory pathway. The VN, through release of acetylcholine, dampens immune cell activation by interacting with α-7 nicotinic acetylcholine receptors. Recent evidence suggests that the vagal innervation of the gastrointestinal tract also plays a major role controlling intestinal immune activation. Indeed, VN electrical stimulation potently reduces intestinal inflammation restoring intestinal homeostasis, whereas vagotomy has the reverse effect. In this review, we will discuss the current understanding concerning the mechanisms and effects involved in the cholinergic anti-inflammatory pathway in the gastrointestinal tract. Deeper investigation on this counter-regulatory neuroimmune mechanism will provide new insights in the cross-talk between the nervous and immune system leading to the identification of new therapeutic targets to treat intestinal immune disease.

Analysis of autonomic modulation during maximal and submaximal work rate and functional capacity in asthmatic children

BACKGROUND

Children with asthma experience changes in functional capacity and autonomic control. The literature suggests that this imbalance is responsible for bronchial hyperresponsiveness, primarily during physical effort.

OBJECTIVE

The aim of the present study was to evaluate variables of autonomic modulation and functional capacity in asthmatic children after maximum and submaximum work rate.

METHODS

A cross-sectional study was carried out with 24 children [18 in the asthma group (AG) and 6 in the control group (CG)]. Evaluations involved heart rate variability (HRV) and functional capacity [shuttle walk test (SWT) and three-minute step test]. Pulmonary function was also evaluated through spirometry and the fractional concentration of expired nitric oxide (FeNO).

RESULTS

The asthma diagnostic variables FEV(1) and FeNO differed significantly between groups (p = .01). Distance traveled on the SWT was lower in the AG (333.13 ± 97.25 m vs. 442.66 ± 127.21 m; p = .04). Perceived exertion was greater in the AG. The HRV variables rMSSD and HF did not decrease significantly during the SWT (maximum work rate) in the AG (p = .01 and .04). FeNO was negatively correlated with FEV(1)/FVC (r = -0.70; p = .004) and positively correlated with pNN50 (r = 0.50; p = .03) in the AG.

CONCLUSION

From the autonomic standpoint, asthmatic and non-asthmatic children respond differently to stress. No withdrawal of parasympathetic cardiac modulation occurs in asthmatic children after maximum work rate. Children with asthma experience changes in functional capacity and lung function may vary depending on the degree of inflammation of the airways.