The relation of aggression, hostility, and anger to lipopolysaccharide-stimulated tumor necrosis factor (TNF)-alpha by blood monocytes from normal men

Associations of the immune system in aggression traits and the role of microglia as mediators

There is an important relationship between the immune system and aggressive behavior. Aggressive encounters acutely increase the levels of proinflammatory cytokines, and there are positive correlations between aggressive traits and peripheral proinflammatory cytokines. Endotoxin lipopolysaccharide (LPS) treatment, which results in peripheral immune activation, decreases aggressive behavior as one of the sickness behavioral symptoms. In contrast, certain brain infections and chronic interferon treatment are associated with increased aggression. Indeed, the effects of proinflammatory cytokines on the brain in aggressive behavior are bidirectional, depending on the type and dose of cytokine, target brain region, and type of aggression. Some studies have suggested that microglial activation and neuroinflammation influence intermale aggression in rodent models. In addition, pathological conditions as well as physiological levels of cytokines produced by microglia play an important role in social and aggressive behavior in adult animals. Furthermore, microglial function in early development is necessary for the establishment of the social brain and the expression of juvenile social behaviors, including play fighting. Overall, this review discusses the important link between the immune system and aggressive traits and the role of microglia as mediators of this link.

Association Between Dietary Patterns and Bullying Among Adolescents in Sao Paulo-Brazil

Previous studies have assessed the association between food consumption and bullying perpetration, but most of them have not broadly assessed food consumption, neither the distinction between forms of bullying. The aim of the study was to evaluate the association between dietary patterns with bullying roles and its different types of bullying perpetration among adolescents. Data on a representative sample of ninth-grade students (N = 2,163; mean age = 14.8 years) taken from Sao Paulo Project for the social development of children and adolescents (SP-PROSO) were used. The independent variables were healthy and unhealthy dietary patterns obtained by exploratory factor analysis. The dependent variables were bullying role (victim-only, bully-only, bully-victim) and bullying perpetration (any type, social exclusion, psychological/verbal aggression, physical aggression, property destruction, sexual harassment). Multinomial and logistic regression models were performed for the total sample and stratified by sex (only for association with sexual harassment), adjusting for covariates. Adolescents who engaged in a healthy dietary pattern were less likely to be bullies (RR 0.67 [0.49, 0.92]), while adolescents with an unhealthy dietary pattern were more likely to be bully-victims (RR 1.29 [1.12, 1.48]). Unhealthy dietary pattern was associated with any type of bullying perpetration (OR 1.24 [1.12, 1.38]), mainly with sexual harassment and physical aggression. Boys who had an unhealthy dietary pattern were more likely to sexually harass another adolescent (OR 2.10 [1.20, 3.66]). In conclusion, adolescents who had a healthy dietary pattern were less likely to perpetrate bullying. Unhealthy dietary pattern was associated with bullying perpetration, especially with sexual harassment by boys.

Nutritional Criminology: Why the Emerging Research on Ultra-Processed Food Matters to Health and Justice

There is mounting concern over the potential harms associated with ultra-processed foods, including poor mental health and antisocial behavior. Cutting-edge research provides an enhanced understanding of biophysiological mechanisms, including microbiome pathways, and invites a historical reexamination of earlier work that investigated the relationship between nutrition and criminal behavior. Here, in this perspective article, we explore how this emergent research casts new light and greater significance on previous key observations. Despite expanding interest in the field dubbed 'nutritional psychiatry', there has been relatively little attention paid to its relevancy within criminology and the criminal justice system. Since public health practitioners, allied mental health professionals, and policymakers play key roles throughout criminal justice systems, a holistic perspective on both historical and emergent research is critical. While there are many questions to be resolved, the available evidence suggests that nutrition might be an underappreciated factor in prevention and treatment along the criminal justice spectrum. The intersection of nutrition and biopsychosocial health requires transdisciplinary discussions of power structures, industry influence, and marketing issues associated with widespread food and social inequalities. Some of these discussions are already occurring under the banner of 'food crime'. Given the vast societal implications, it is our contention that the subject of nutrition in the multidisciplinary field of criminology-referred to here as nutritional criminology-deserves increased scrutiny. Through combining historical findings and cutting-edge research, we aim to increase awareness of this topic among the broad readership of the journal, with the hopes of generating new hypotheses and collaborations.

The association between social class and aggression: A meta-analytic review

RATIONALE

Substantial evidence links social class with aggression. Despite lower social class being recognized as a risk factor for high levels of aggression, the findings of this association have been inconsistent. Some studies have indeed illustrated that a social class level is inversely associated with aggression, while other studies have demonstrated positive or null associations.

OBJECTIVE

To clarify previously inconsistent findings, this meta-analysis assesses the overall magnitude of this relationship and examines the potential moderators.

METHODS

A total of 268 studies met the inclusion criteria, and we used 546 effect sizes in 357 independent samples from these studies. A random-effects meta-analytic model was employed and several moderator analyses were conducted.

RESULTS

Overall, social class shared a small but significant negative relationship with aggression (r = -0.092). Moderator analyses suggested that study-level (e.g., type of study, and national differences), sample-level (e.g., age), class-level (e.g., type, assessment, and source of social class), and aggression-level (e.g., type of aggression) characteristics accounted for heterogeneity in the relationship. Additional analyses also revealed the robustness of these effects with little evidence of publication bias.

CONCLUSIONS

Living in disadvantaged socioecological environments, lower-class individuals may exhibit more aggression to adapt to threats. Moreover, the relationship between social class and aggression is not fixed and can change with specific contexts, and aggression is not an essential feature of a particular social group. This research hopes to inspire future studies to explore the association between social class and aggression more thoroughly. Additionally, it provides insights into how to reduce aggression among lower-class individuals.

Psychiatric Symptoms, Aggression, and Sexual Dysfunction Among Patients With Benign Anal Conditions

INTRODUCTION

The aim of this study was to investigate the incidence of general psychiatric symptoms, aggression levels, and sexual dysfunction in patients with benign anorectal diseases and compare the results with those of healthy control subjects.

METHODS

We prospectively enrolled consecutive adult patients who presented for treatment of benign perianal diseases and healthy control subjects between June 2017 and December 2018. All patients had either grade 3 or 4 hemorrhoidal disease or perianal fistula with active discharge who had not undergone previous anorectal surgery. We also included a control group with benign subcutaneous lumps presenting for minor surgery. We used the Symptom Checklist-90-Revised Form to evaluate general psychiatric symptoms, the Buss-Perry Aggression Questionnaire (BPAQ) to evaluate aggression levels, and the Arizona Sexual Experiences Scale to evaluate sexual dysfunction.

RESULTS

A total of 563 patients were assessed for eligibility; after exclusions, 94 with anal fistula, 89 with hemorrhoids, and 59 healthy control subjects were enrolled. The groups were similar with regard to age, gender, and educational level. Physical and verbal aggression, anger, and total BPAQ score were significantly higher in patients with perianal fistula than in those with hemorrhoidal disease and healthy control subjects (P < .001).

CONCLUSION

This study suggests that patients with perianal fistula have higher levels of aggression than healthy control subjects and those with hemorrhoidal disease. One must bear this in mind during preoperative patient evaluations and obtaining informed consent. Further studies are needed to investigate the reason for this association and potential causality.

Understanding the Role of Oxidative Stress, Neuroinflammation and Abnormal Myelination in Excessive Aggression Associated with Depression: Recent Input from Mechanistic Studies

Aggression and deficient cognitive control problems are widespread in psychiatric disorders, including major depressive disorder (MDD). These abnormalities are known to contribute significantly to the accompanying functional impairment and the global burden of disease. Progress in the development of targeted treatments of excessive aggression and accompanying symptoms has been limited, and there exists a major unmet need to develop more efficacious treatments for depressed patients. Due to the complex nature and the clinical heterogeneity of MDD and the lack of precise knowledge regarding its pathophysiology, effective management is challenging. Nonetheless, the aetiology and pathophysiology of MDD has been the subject of extensive research and there is a vast body of the latest literature that points to new mechanisms for this disorder. Here, we overview the key mechanisms, which include neuroinflammation, oxidative stress, insulin receptor signalling and abnormal myelination. We discuss the hypotheses that have been proposed to unify these processes, as many of these pathways are integrated for the neurobiology of MDD. We also describe the current translational approaches in modelling depression, including the recent advances in stress models of MDD, and emerging novel therapies, including novel approaches to management of excessive aggression, such as anti-diabetic drugs, antioxidant treatment and herbal compositions.

The Role of the IL-10 (-819C/T), TNFA (-308G/A) and ENOS (-786T/C) Polymorphisms of Impulsive and Aggressive Personality Traits in Cocaine/Crack Users

Cytokines and nitric oxide have been associated with impulsive and aggressive personality traits. We conducted the first study that investigated the role of SNPs in cytokines and nitric oxide genes and the influence in the progression of aggressive and impulsive behavior in 107 of cocaine and crack users. In this case-control, IL-10 (-819C/T), TNFA (-308G/A) and ENOS (-786T/C) polymorphisms were determined by Real-Time PCR. In addition, the relationship between these polymorphisms and Impulsivity and Aggression was determined. We found that the physical aggressiveness sub score was negatively correlated with the C allele of -819C/T polymorphism of the IL-10 (b = -0.14; p = 0.04). The T allele of the SNP -786T/C of the ENOS gene positively predicts traits of physical aggressiveness (b = 0.14; p = 0.04). The GA genotype (b = 0.22; p = 0.01) and the A allele (b = 0.15; p = 0.02) of -308 G/A polymorphism of the TNFA were positively correlated with aggressiveness physical. The GA genotype (b = 0.20; p = 0.03) was positively correlated with aggressiveness verbal. IL-10 (-819C/T), TNFA (-308G/A) and ENOS (-786T/C) polymorphisms might be associated with high risk of aggressive and impulsive behavior.

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.

Identification and expression pattern of the sex determination gene fruitless-like in Cherax quadricarinatus

The fruitless (fru) gene has an important function in the courtship behavior and sex determination pathway of Drosophila melanogaster; however, the fru gene has never been reported in shrimps. In this study, the fruitless-like gene was identified in Cherax quadricarinatus (Cqfru) and is reported here for the first time. A sequence analysis revealed a conserved BTB domain in Cqfru which is the same as fru in D. melanogaster. An analysis of the expression level of Cqfru showed that it was highly expressed in the gastrula stage during embryonic development. Furthermore, in situ hybridization and expression distribution in tissues showed that its sexually dimorphic expression may be focused on the hepatopancreas, brains, and gonads. The gonads, brains, and hepatopancreas of males had a higher expression level of Cqfru than those of females; however, the expression level of the abdominal ganglion was found to be higher in females than in males in this study. The results of an RNA interference treatment showed that a knockdown of Cqfru reduced the expression of the insulin-like androgenic gland hormone (IAG) and tumor necrosis factor (TNF). The characteristic fru gene in shrimps is reported here for the first time, with the results providing basic information for research into the sex-determination mechanism in C. quadricarinatus.

Matrine ameliorates the inflammatory response and lipid metabolism in vascular smooth muscle cells through the NF-κB pathway

Atherosclerosis is a chronic inflammatory disease associated with inflammatory responses and the uncontrolled proliferation and excessive apoptosis of vascular smooth muscle cells. However, the effects of matrine on the inflammatory response, abnormal lipid metabolism and cell proliferation and apoptosis marker proteins in human aortic vascular smooth muscle cells (HAVSMCs) have not been elucidated. Therefore, the present study aimed to investigate the effect of matrine on an in vitro model of atherosclerosis using HAVSMCs. The HAVSMCs were divided into normal, model and matrine groups. The model group was treated with oxidized low-density lipoprotein (oxLDL), the matrine group was treated with oxLDL and matrine and the normal group was treated with physiological saline. Total cholesterol (TC), free cholesterol (FC) and cholesterol ester (CE) levels were measured in the cell supernatant. In addition, the relative mRNA levels of inflammatory factors were quantified using reverse transcription-quantitative PCR, and the cell proliferation and apoptosis rates were evaluated using Cell Counting Kit-8 and flow cytometry assays, respectively. The expression levels of proteins associated with proliferation and apoptosis were also determined using western blotting. The levels of TC, FC and CE and the mRNA levels of IL-1β, IL-6, and TNF-α in the matrine group were lower than those in the model group, but higher than those in the normal group. After 48 and 96 h of treatment, the cell proliferation and apoptotic rates were lower in the matrine group compared with the model group. The relative expression levels of Ki-67, proliferating cell nuclear antigen and Bax were decreased, while that of Bcl-2 was increased in the matrine group compared with the model group. In addition, the relative protein expression of nuclear factor κB (NF-κB) in the matrine group was lower than that in the model group, but higher than that in the normal group. In summary, matrine inhibited activation of the NF-κB pathway and reduced cell proliferation and apoptosis in the oxLDL-induced atherosclerosis model, and exhibited anti-inflammatory effects. These results suggest that matrine attenuated abnormal biological reactions in HAVSMCs through the NF-κB pathway.

Infection threat shapes our social instincts

We social animals must balance the need to avoid infections with the need to interact with conspecifics. To that end we have evolved, alongside our physiological immune system, a suite of behaviors devised to deal with potentially contagious individuals. Focusing mostly on humans, the current review describes the design and biological innards of this behavioral immune system, laying out how infection threat shapes sociality and sociality shapes infection threat. The paper shows how the danger of contagion is detected and posted to the brain; how it affects individuals’ mate choice and sex life; why it strengthens ties within groups but severs those between them, leading to hostility toward anyone who looks, smells, or behaves unusually; and how it permeates the foundation of our moral and political views. This system was already in place when agriculture and animal domestication set off a massive increase in our population density, personal connections, and interaction with other species, amplifying enormously the spread of disease. Alas, pandemics such as COVID-19 not only are a disaster for public health, but, by rousing millions of behavioral immune systems, could prove a threat to harmonious cohabitation too.

Relationships between inflammatory markers and suicide risk status in major depression

Pro-inflammatory status has been implicated in depression and suicidal behaviors. Polyunsaturated fatty acids (PUFAs) and cytokines, two types of inflammatory biomarkers, have been associated with suicide, independent of depression severity. How these biomarkers relate to each other is less clear. We measured plasma phospholipid levels of arachidonic acid (AA%), docosahexaenoic acid (DHA%), and eicosapentaenoic acid (EPA%) as a percentage of total phospholipids, as well as serum interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α), in 80 patients with major depressive disorder (MDD) and 24 healthy controls (HC). Individual PUFA and cytokine species were compared using ANOVA across four suicide risk-stratified groups: 1) highest-risk, recent (within 5 years) suicide attempters (n = 20); 2) high-risk, severe current suicidal ideators (having intent or plan) with no recent attempt history (n = 22); 3) low-risk, current non-ideators who were also lifetime non-attempters (n = 38); and 4) HC (n = 24). None of the participants were enrolled following an acute suicide attempt. Of biomarkers studied, only DHA% (p = 0.012) and IL-1β (p = 0.002) differed between groups. In post-hoc testing, DHA% was lower in attempters than ideators (p = 0.018) or MDD non-ideators (trend level, p = 0.073). IL-1β was lowest in attempters, differentiating them from ideators (p = 0.009) and HC (p = 0.004). Recent suicide attempt, one of the most powerful predictors of suicide risk, was also most closely tied to inflammatory indices in this study. Low DHA% as an indicator of suicide risk is consistent with previous reports; however, lower IL-1β was unexpected and may relate to acuity/chronicity of inflammation. There is a need for prospective studies of immune status with respect to suicidal behaviors.

Biomarkers in aggression

Aggressive behavior exerts an enormous impact on society remaining among the main causes of worldwide premature death. Effective primary interventions, relying on predictive models of aggression that show adequate sensitivity and specificity are currently lacking. One strategy to increase the accuracy and precision of prediction would be to include biological data in the predictive models. Clearly, to be included in such models, biological markers should be reliably associated with the specific trait under study (i.e., diagnostic biomarkers). Aggression, however, is phenotypically highly heterogeneous, an element that has hindered the identification of reliable biomarkers. However, current research is trying to overcome these challenges by focusing on more homogenous aggression subtypes and/or by studying large sample size of aggressive individuals. Further advance is coming by bioinformatics approaches that are allowing the integration of inter-species biological data as well as the development of predictive algorithms able to discriminate subjects on the basis of the propensity toward aggressive behavior. In this review we first present a brief summary of the available evidence on neuroimaging of aggression. We will then treat extensively the data on genetic determinants, including those from hypothesis-free genome-wide association studies (GWAS) and candidate gene studies. Transcriptomic and neurochemical biomarkers will then be reviewed, and we will dedicate a section on the role of metabolomics in aggression. Finally, we will discuss how biomarkers can inform the development of new pharmacological tools as well as increase the efficacy of preventive strategies.

Exercise Counteracts the Cardiotoxicity of Psychosocial Stress

Physical inactivity and psychosocial stress are prevalent in residents of the United States. The purpose of this article is to review the interaction between these 2 conditions and examine the effects of exercise on stress and cardiovascular (CV) health. A query of scientific references between 1974 to 2018 was performed using the PubMed search engine accessing the MEDLINE database using the search terms psychosocial stress, CV disease (CVD), physical activity, exercise, cardiac rehabilitation, and team sports. Psychosocial stress is a strong independent risk factor for adverse CV events. Conversely, people who experience CV events subsequently have drastically elevated rates of new-onset mental health disorders, including depression and anxiety. Psychosocial stress and CVD often trigger self-reinforcing feedback loops that can worsen mental health and cardiac prognosis. Exercise predictably improves CV health and prognosis and also is effective at lowering levels of psychosocial stress. Group exercise in particular seems to provide social support while at the same time boosting fitness levels and, thus, may be the single most important intervention for patients with concomitant CVD and emotional stress. Collaborative physical activity, such as group exercise, team sports, interactive physical play, and cardiac rehabilitation programs, have the potential to improve mental health and CV prognosis.

Febrile and sleep responses to an immune challenge are affected by trait aggressiveness in rats

Sleep is altered in response to an immune challenge: non-rapid eye movement (NREM) sleep is increased and fragmented, REM sleep is inhibited. Sleep and immune response are affected by stress: several stressors inhibit sleep and increase waking time; stress-induced cortisol secretion affects the immune response, with immunosuppressive effects. Different levels of trait aggressiveness are associated with specific patterns of neuroendocrine and autonomic stress responsiveness. Aim of this study was to test the hypothesis that trait aggressiveness, by affecting response to stressors, modifies sleep alterations induced by the activation of the immune response. To this aim, rats were selected on the basis of their latency time to attack a male intruder in the resident-intruder test. Animals were instrumented for chronic recordings of sleep-wake activity and injected, intraperitoneally, with an immune challenge (250 μg/kg lipopolysaccharide - LPS, a component of gram-negative bacterial cell wall). Here we report that high aggressive (HA) rats responded to an immune challenge with a 24-h long increase in cortical brain temperature. During the first 12 post-injection hours, HA rats also responded with a prolonged increase in NREM sleep amount, and a 5-h long and continuous inhibition of REM sleep. In HA rats, the LPS-induced increase in the amount of time spent in NREM sleep was due to an increase in the number of episodes of this sleep phase, without any change in the bout duration. The LPS-induced REM sleep inhibition observed in HA rats was due to a decrease in both the number and duration of REM sleep bouts. In HA rats, during REM sleep, LPS administration significantly reduced the power of the EEG theta band. In non-aggressive (NA) rats, in response to LPS administration, cortical brain temperature was increased only for two hours, NREM sleep was unaffected, and REM sleep inhibition was scattered along the first 8 post-injection hours. The LPS-induced changes in the number of NREM sleep bouts of NA rats were limited to few and scattered hours, with a change in bout duration only in a single hour. A combination of decreases, in few hours, in both REM sleep bouts and their duration contributed to the REM sleep inhibition observed in NA rats. In NA rats, the power of EEG theta band was not modified, during REM sleep, by LPS administration. Gross motor activity was inhibited in both HA and NA rats. Results of this study show that trait aggressiveness affects febrile and sleep responses to an immune challenge.

Cytokine variations within brain structures in rats selected for differences in aggression

The present study examined the content of cytokines (IL-1β, IL-2, IL-6, IL-10) in the brain structures (the hypothalamus, striatum, frontal cortex, and hippocampus) in two rat lines selected for differences in fear-induced aggression at 2, 4, and 24 h after a peripheral injection of saline or lipopolysaccharide (LPS, 250 μg/kg). LPS stimulation elevated cytokine activity above baseline levels in both aggressive and nonaggressive rats, but the pattern, time course of cytokine changes, and their regional characteristics varied according to the animal aggressiveness. After LPS administration, aggressive rats showed increased levels of IL-1β in the hypothalamus at 2 and 4 h and in the frontal cortex at 4 and 24 h compared to LPS-treated nonaggressive line. IL-2 was increased in the frontal cortex and striatum of aggressive rats within 24 h, while IL-6 elevation in the hypothalamus was found at 4 h and in the frontal cortex at 2 and 4 h. In the hippocampus, the levels of IL-1β, IL-2, and IL-6 were lower in LPS-treated aggressive rats than in nonaggressive animals. The levels of anti-inflammatory cytokine IL-10 were also decreased in all brain structures of aggressive rats receiving LPS. The results indicate that genetic predisposition to increased aggression is associated with a time and region-dependent changes in the levels of pro- and anti-inflammatory cytokines.

Aggression, impulsivity and inflammatory markers as risk factors for suicidal behavior

BACKGROUND

Increased inflammatory markers have been linked to suicidal behavior in numerous studies. Measures of aggression and of impulsivity also comprise risks factors for suicidal behavior and there is evidence that inflammatory markers correlate with these traits. The following analyses compare suicide attempters and non-attempters to determine whether inflammatory markers mediate relationships between aggression or impulsivity and proclivities to suicidal behavior.

METHODS

Investigators at three academic centers recruited patients in major depressive episodes who had a history of two or more suicide attempts (n = 79), or who had no history of suicide attempts (n = 123). Analyses compared these groups by five inflammatory marker levels and by measures of aggression and of impulsivity.

RESULTS

These results did not confirm the hypotheses that cytokine levels would explain relationships between aggressive behavior and suicide attempt history. However, scores for aggressive behavior and for impulsivity were significantly higher among suicide attempters. One of five of the inflammatory markers, (IL-1β), distinguished the two groups with lower values in the suicide attempt group. IL-1β levels correlated inversely with measures of aggression but neither impulsivity or aggressive behavior appear to explain the association between IL-1β levels and suicide attempt status.

CONCLUSION

These results identify recent aggressive behavior, higher levels of impulsivity, and lower levels of IL-1β as risk factors for a history of multiple suicide attempts in a group suffering from major depressive episodes. These measures appear to be additive in their effects.

Aerobic Exercise Training and Inducible Inflammation: Results of a Randomized Controlled Trial in Healthy, Young Adults

Background Consensus panels regularly recommend aerobic exercise for its health-promoting properties, due in part to presumed anti-inflammatory effects, but many studies show no such effect, possibly related to study differences in participants, interventions, inflammatory markers, and statistical approaches. This variability makes an unequivocal determination of the anti-inflammatory effects of aerobic training elusive. Methods and Results We conducted a randomized controlled trial of 12 weeks of aerobic exercise training or a wait list control condition followed by 4 weeks of sedentary deconditioning on lipopolysaccharide (0, 0.1, and 1.0 ng/mL)-inducible tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and on toll-like receptor 4 in 119 healthy, sedentary young adults. Aerobic capacity by cardiopulmonary exercise testing was measured at study entry (T1) and after training (T2) and deconditioning (T3). Despite a 15% increase in maximal oxygen consumption, there were no changes in inflammatory markers. Additional analyses revealed a differential longitudinal aerobic exercise training effect by lipopolysaccharide level in inducible TNF -α ( P=0.08) and IL-6 ( P=0.011), showing T1 to T2 increases rather than decreases in inducible (lipopolysaccharide 0.1, 1.0 versus 0.0 ng/mL) TNF- α (51% increase, P=0.041) and IL-6 (42% increase, P=0.11), and significant T2 to T3 decreases in inducible TNF- α (54% decrease, P=0.007) and IL-6 (55% decrease, P<0.001). There were no significant changes in either group at the 0.0 ng/mL lipopolysaccharide level for TNF- α or IL-6. Conclusions The failure to support the primary hypotheses and the unexpected post hoc findings of an exercise-training-induced proinflammatory response raise questions about whether and under what conditions exercise training has anti-inflammatory effects. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 01335737.

Aggression, Social Stress, and the Immune System in Humans and Animal Models

Social stress can lead to the development of psychological problems ranging from exaggerated anxiety and depression to antisocial and violence-related behaviors. Increasing evidence suggests that the immune system is involved in responses to social stress in adulthood. For example, human studies show that individuals with high aggression traits display heightened inflammatory cytokine levels and dysregulated immune responses such as slower wound healing. Similar findings have been observed in patients with depression, and comorbidity of depression and aggression was correlated with stronger immune dysregulation. Therefore, dysregulation of the immune system may be one of the mediators of social stress that produces aggression and/or depression. Similar to humans, aggressive animals also show increased levels of several proinflammatory cytokines, however, unlike humans these animals are more protected from infectious organisms and have faster wound healing than animals with low aggression. On the other hand, subordinate animals that receive repeated social defeat stress have been shown to develop escalated and dysregulated immune responses such as glucocorticoid insensitivity in monocytes. In this review we synthesize the current evidence in humans, non-human primates, and rodents to show a role for the immune system in responses to social stress leading to psychiatric problems such as aggression or depression. We argue that while depression and aggression represent two fundamentally different behavioral and physiological responses to social stress, it is possible that some overlapped, as well as distinct, pattern of immune signaling may underlie both of them. We also argue the necessity of studying animal models of maladaptive aggression induced by social stress (i.e., social isolation) for understanding neuro-immune mechanism of aggression, which may be relevant to human aggression.

More inflammation but less brain-derived neurotrophic factor in antisocial personality disorder

Antisocial personality disorder (ASPD) is highly comorbid with substance use disorders (SUDs). We hypothesize that chronic neuroinflammation and the loss of neurotrophic factors prompts the pathogenesis of both disorders. We used ELISA to measure plasma levels of proinflammatory (tumor necrosis factor-α [TNF-α], C-reactive protein [CRP]) and anti-inflammatory factors (transforming growth factor-β1 [TGF-β1] and interleukin-10 [IL-10]), and brain-derived neurotrophic factor (BDNF) in male patients with ASPD (n=74), SUDs (n=168), ASPD comorbid with SUDs (ASPD+SUDs) (n=438), and Healthy Controls (HCs) (n=81). A multivariate analysis of covariance (MANCOVA) controlled for possible confounders was used to compare cytokines and BDNF levels between groups. The results of MANCOVA adjusted for age showed a significant (p<0.001) main effect of diagnosis on inflammatory factors and BDNF expression in these groups. ASPD, SUDs, and ASPD+SUDs patients had significantly (p<0.001) higher TNF-α levels but lower TGF-β1 and BDNF levels. SUDs and ASPD+SUDs patients had higher IL-10 levels than did ASPD patients and HCs. There was no difference in IL-10 levels between HCs and ASPD. Moreover, subgrouping SUDs and ASPD±SUDs into opioid use disorder (OUD) and other SUDs groups showed that the IL-10 levels were specifically higher in OUD and ASPD±OUD groups than other SUDs (P≤0.001). We conclude that uncontrolled inflammation and losing neurotrophic factors, with or without comorbid SUDs, underlies ASPD. IL-10 expression might be more specifically associated with OUD.

Plasma Cytokine Levels in Relation to Neuropsychiatric Symptoms and Cognitive Dysfunction in Huntington's disease

BACKGROUND

In Huntington's disease (HD) the innate immune system is activated, as reflected by increased plasma levels of different cytokines.

OBJECTIVE

To explore whether increased cytokine levels are associated with neuropsychiatric symptoms and cognitive dysfunction in HD mutation carriers.

METHOD

Plasma cytokine levels of TNF-alpha, interleukin (IL)-1ra, IL-1β, IL-5, IL-6, IL-8 and Il-10 were assessed in 124 HD mutation carriers at two time points 2 years apart (totalling 214 observations). Using multilevel regression analysis, cytokines were analysed in relation to neuropsychiatric symptoms and cognitive dysfunction. Depressed mood was assessed with the depression subscale of the Problem Behaviours Assessment (PBA), apathy with the Apathy Scale, and irritability with the Irritability Scale. Cognitive functioning was assessed using the Mini-Mental State Examination (MMSE) and a battery of executive cognitive functioning tests, aggregated into an executive cognitive functioning (ExCog) score.

RESULTS

Inverse associations were found in adjusted models between IL-6 and ExCog score (β= -0.114; p = 0.01) and between IL-1ra and ExCog score (β= -0.110; p = 0.02). No associations between cytokine levels and any of the other neuropsychiatric symptom scores remained statistically significant in adjusted models.

CONCLUSION

Higher plasma levels of IL-6 and IL-1ra are weakly associated with cognitive dysfunction in HD, but not with other neuropsychiatric symptoms.

Effectiveness of conservative interventions for sickness and pain behaviors induced by a high repetition high force upper extremity task

Background

Systemic inflammation is known to induce sickness behaviors, including decreased social interaction and pain. We have reported increased serum inflammatory cytokines in a rat model of repetitive strain injury (rats perform an upper extremity reaching task for prolonged periods). Here, we sought to determine if sickness behaviors are induced in this model and the effectiveness of conservative treatments.

Methods

Experimental rats underwent initial training to learn a high force reaching task (10 min/day, 5 days/week for 6 weeks), with or without ibuprofen treatment (TRHF vs. TRHF + IBU rats). Subsets of trained animals went on to perform a high repetition high force (HRHF) task for 6 or 12 weeks (2 h/day, 3 days/week) without treatment, or received two secondary interventions: ibuprofen (HRHF + IBU) or a move to a lower demand low repetition low force task (HRHF-to-LRLF), beginning in task week 5. Mixed-effects models with repeated measures assays were used to assay duration of social interaction, aggression, forepaw withdrawal thresholds and reach performance abilities. One-way and two-way ANOVAs were used to assay tissue responses. Corrections for multiple comparisons were made.

Results

TRHF + IBU rats did not develop behavioral declines or systemic increases in IL-1beta and IL-6, observed in untreated TRHF rats. Untreated HRHF rats showed social interaction declines, difficulties performing the operant task and forepaw mechanical allodynia. Untreated HRHF rats also had increased serum levels of several inflammatory cytokines and chemokines, neuroinflammatory responses (e.g., increased TNFalpha) in the brain, median nerve and spinal cord, and Substance P and neurokinin 1 immunoexpression in the spinal cord. HRHF + IBU and HRHF-to-LRLF rats showed improved social interaction and reduced inflammatory serum, nerve and brain changes. However, neither secondary treatment rescued HRHF-task induced forepaw allodynia, or completely attenuated task performance declines or spinal cord responses.

Conclusions

These results suggest that inflammatory mechanisms induced by prolonged performance of high physical demand tasks mediate the development of social interaction declines and aggression. However, persistent spinal cord sensitization was associated with persistent behavioral indices of discomfort, despite use of conservative secondary interventions indicating the need for prevention or more effective interventions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12868-017-0354-3) contains supplementary material, which is available to authorized users.

Role of Inflammation in Suicide: From Mechanisms to Treatment

Suicidal behavior is complex and manifests because of a confluence of diverse factors. One such factor involves dysregulation of the immune system, which has been linked to the pathophysiology of suicidal behavior. This review will provide a brief description of suicidality and discuss the contribution of upstream and downstream factors in the etiology of suicidal behavior, within the contextual framework of inflammation. The contribution of inflammatory conditions such as traumatic brain injury, autoimmune disorders, and infections to neuropsychiatric symptoms and suicidality is only beginning to be explored. We will summarize studies of inflammation in the etiology of suicide, and provide a neurobiological basis for different mechanisms by which inflammation might contribute to the pathophysiology. Finally, we will review treatments that affect upstream and downstream pathways related to inflammation in suicidality.

Plasma levels of Th17-related cytokines and complement C3 correlated with aggressive behavior in patients with schizophrenia

Increasing evidence indicates that immune inflammatory processes, especially autoimmune reaction, should be considered in the pathophysiology of schizophrenia and aggressive behavior. The present study aimed to explore the correlation between immune factors (C3 and Th17-related cytokines) and aggressive behavior in schizophrenia patients. Forty schizophrenia patients and forty age- and gender-matched healthy controls participated in the study. Blood samples were assessed by ELISA upon enrollment. Positive and negative syndrome scale (PANSS) and modified overt aggression scale (MOAS) were used to estimate the severity and aggressive symptoms of schizophrenia patients. Plasma levels of IL-17, IL-23, and TGF-β1 in schizophrenia patients were significantly higher than those in healthy controls [(37.63±17.82) vs. (29.34±10.38)pg/ml, p=0.02; (101.40±135.26) vs. (13.09±5.94) pg/ml, p=0.01; (2864.57±2163.61) vs. (1839.69±1797.73)pg/ml, p=0.04], whereas C3 levels were significantly lower in schizophrenia patients [( 120,479.67± 65,612.50) vs. ( 208,060.21± 217,008.21)ng/ml, p=0.02]. IL-17, IL-23, and TGF-β1 levels were positively related to total scores of MOAS (p=0.02, p=0.02 and p=0.03, respectively) and PANSS (p=0.04, p=0.04 and p=0.02, respectively), whereas C3 levels were negatively related to total PANSS scores (p=0.03). IL-17 and IL-23 levels were positively correlated with PANSS excited component scores (p=0.04 and p=0.01, respectively). Our findings suggested that the Th17-related cytokine levels were positively related to the severity of schizophrenia and aggressive behavior, whereas C3 levels were negatively related to the severity of schizophrenia. This study demonstrated that elevated levels of Th17-related cytokines and decreased levels of C3 could be potential biomarkers for schizophrenia and aggressive behavior.

Trait Hostility and Acute Inflammatory Responses to Stress in the Laboratory

Hostility has been associated with higher basal levels of inflammation. The present study evaluated the association of hostility with acute stress-induced changes in inflammatory activity. One hundred and ninety-nine healthy men and women, aged 19–64 years, were exposed to a stress protocol involving four interpersonal stressors. Participants completed the Cook-Medley Hostility questionnaire and provided two blood samples for the measurement of inflammatory biomarkers (CRP, Il-6, MPO, TNF-α, MCP-1, Il-8, Il-10, and Il-18), prior to and following exposure to a standardized stress protocol. In univariate analyses, hostility was associated with significantly higher TNF-α, but lower Il-8 and Il-18 values post-stress, though only Il-8 remained significant after controlling for baseline differences. In multivariate analyses, a significant Age by Hostility interaction emerged for Il-6, while sex moderated the relation between hostility and Il-10 reactivity. Following stress, hostility was associated with greater pro-inflammatory Il-6 activity among younger individuals and to decreased anti-inflammatory Il-10 activity in women. Future research is needed to replicate these findings and to evaluate their implication for disease.

Low-dose lipopolysaccharide (LPS) inhibits aggressive and augments depressive behaviours in a chronic mild stress model in mice

Background

Aggression, hyperactivity, impulsivity, helplessness and anhedonia are all signs of depressive-like disorders in humans and are often reported to be present in animal models of depression induced by stress or by inflammatory challenges. However, chronic mild stress (CMS) and clinically silent inflammation, during the recovery period after an infection, for example, are often coincident, but comparison of the behavioural and molecular changes that underpin CMS vs a mild inflammatory challenge and impact of the combined challenge is largely unexplored. Here, we examined whether stress-induced behavioural and molecular responses are analogous to lipopolysaccharide (LPS)-induced behavioural and molecular effects and whether their combination is adaptive or maladaptive.

Methods

Changes in measures of hedonic sensitivity, helplessness, aggression, impulsivity and CNS and systemic cytokine and 5-HT-system-related gene expression were investigated in C57BL/6J male mice exposed to chronic stress alone, low-dose LPS alone or a combination of LPS and stress.

Results

When combined with a low dose of LPS, chronic stress resulted in an enhanced depressive-like phenotype but significantly reduced manifestations of aggression and hyperactivity. At the molecular level, LPS was a strong inducer of TNFα, IL-1β and region-specific 5-HT_2A mRNA expression in the brain. There was also increased serum corticosterone as well as increased TNFα expression in the liver. Stress did not induce comparable levels of cytokine expression to an LPS challenge, but the combination of stress with LPS reduced the stress-induced changes in 5-HT genes and the LPS-induced elevated IL-1β levels.

Conclusions

It is evident that when administered independently, both stress and LPS challenges induced distinct molecular and behavioural changes. However, at a time when LPS alone does not induce any overt behavioural changes per se, the combination with stress exacerbates depressive and inhibits aggressive behaviours.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0572-0) contains supplementary material, which is available to authorized users.

The role of cytokines in the pathophysiology of suicidal behavior

OBJECTIVE

Immune dysregulation has been implicated in depression and other psychiatric disorders. What is less clear is how immune dysregulation can affect risk of suicidal behavior. We reviewed the scientific literature concerning cytokines related to suicidal ideation, suicidal behavior and suicide, and surveyed clinical and neurobiological factors associated with cytokine levels that may modulate effects of inflammation on suicide risk.

METHODS

We searched PubMed, Embase, Scopus and PsycINFO for relevant studies published from 1980 through February, 2015. Papers were included if they were written in English and focused on cytokine measurements in patients with suicidal behaviors.

RESULTS

The literature search yielded 22 studies concerning cytokines and suicidal ideation, suicide attempts or suicide completion. The most consistent finding was elevated interleukin (IL)-6, found in 8 out of 14 studies, in CSF, blood, and postmortem brain. In one study, IL-6 in CSF was also found to be higher in violent than nonviolent attempters and to correlate with future suicide completion. Low plasma IL-2 was observed in 2 studies of suicide attempters, while divergent results were seen for tumor necrosis factor (TNF)-α, interferon (IFN)-γ, transforming growth factor (TGF)-β, IL-4, and soluble Il-2 receptors.

CONCLUSIONS

Given the complexity suggested by the heterogenous cytokine findings, putative mediators and moderators of inflammation on suicidal behavior merit further study. Elevated IL-6 was the most robust cytokine finding, associated with suicidal ideation and both nonfatal suicide attempts and suicides. Future studies should evaluate the predictive value of high IL-6, consider how this may alter brain function to impact suicidal behavior, and explore the potential beneficial effects of reducing IL-6 on suicide risk.

Immune reactivity in rats selected for the enhancement or elimination of aggressiveness towards humans

This study analyzes immune reactivity in two lines of rats selected for the enhancement or elimination of aggressiveness toward humans. Compared to nonaggressive line, aggressive rats showed increased blood ratio of CD4(+) and CD8(+)T lymphocytes, monocyte chemoattractant protein (MCP)-1 level both before and after immunization with sheep red blood cells (SRBC), enhanced IgM-immune response, as well as decreased level of interleukin (IL)-1α before immunization. However, antigen administration produced IL-1α increase in aggressive rats and its decrease in nonaggressive rats compared to non-immunized rats of the same lines. In addition, line-dependent alterations of T lymphocyte distribution in response to immune activation have been found only in the spleen. It is suggested that genetic differences in aggressive behavior may contribute to differences in immune function.

The developmental origins of chronic physical aggression: biological pathways triggered by early life adversity

Longitudinal epidemiological studies with birth cohorts have shown that physical aggression in humans does not appear suddenly in adolescence as commonly thought. In fact, physically aggressive behaviour is observed as early as 12 months after birth, its frequency peaks around 2-4 years of age and decreases in frequency until early adulthood. However, a minority of children (3-7%) maintain a high frequency of physical aggression from childhood to adolescence and develop serious social adjustment problems during adulthood. Genetic factors and early social experiences, as well as their interaction, have been shown to play an important role in the development of chronic aggressive behaviour. However, the biological mechanisms underlying these associations are just beginning to be uncovered. Recent evidence suggests that epigenetic mechanisms are responsive to adverse environments and could be involved in the development of chronic aggression. Using both gene candidate and genomic approaches, recent studies have identified epigenetic marks, such as DNA methylation alterations in genes involved in the stress response and the serotonin and immune systems to be partly responsible for the long-lasting effects of early adversity. Further longitudinal studies with biological, environmental and behavioural assessments from birth onwards are needed to elucidate the sequence of events that leads to these long-lasting epigenetic marks associated with early adversity and aggression.

The role of multiple negative social relationships in inflammatory cytokine responses to a laboratory stressor

The present study examined the unique impact of perceived negativity in multiple social relationships on endocrine and inflammatory responses to a laboratory stressor. Via hierarchical cluster analysis, those who reported negative social exchanges across relationships with a romantic partner, family, and their closest friend had higher mean IL-6 across time and a greater increase in TNF-α from 15 min to 75 min post stress. Those who reported negative social exchanges across relationships with roommates, family, and their closest friend showed greater IL-6 responses to stress. Differences in mean IL-6 were accounted for by either depressed mood or hostility, whereas differences in the cytokine stress responses remained significant after controlling for those factors. Overall, this research provides preliminary evidence to suggest that having multiple negative relationships may exacerbate acute inflammatory responses to a laboratory stressor independent of hostility and depressed mood.

A review of the neuro- and systemic inflammatory responses in post concussion symptoms: Introduction of the "post-inflammatory brain syndrome" PIBS

Post-concussion syndrome is an aggregate of symptoms that commonly present together after head injury. These symptoms, depending on definition, include headaches, dizziness, neuropsychiatric symptoms, and cognitive impairment. However, these symptoms are common, occurring frequently in non-head injured controls, leading some to question the existence of post-concussion syndrome as a unique syndrome. Therefore, some have attempted to explain post-concussion symptoms as post-traumatic stress disorder, as they share many similar symptoms and post-traumatic stress disorder does not require head injury. This explanation falls short as patients with post-concussion syndrome do not necessarily experience many key symptoms of post-traumatic stress disorder. Therefore, other explanations must be sought to explain the prevalence of post-concussion like symptoms in non-head injury patients. Many of the situations in which post-concussion syndrome like symptoms may be experienced such as infection and post-surgery are associated with systemic inflammatory responses, and even neuroinflammation. Post-concussion syndrome itself has a significant neuroinflammatory component. In this review we examine the evidence of neuroinflammation in post-concussion syndrome and the potential role systemic inflammation plays in post-concussion syndrome like symptoms. We conclude that given the overlap between these conditions and the role of inflammation in their etiologies, a new term, post-inflammatory brain syndromes (PIBS), is necessary to describe the common outcomes of many different inflammatory insults. The concept of post-concussion syndrome is in its evolution therefore, the new term post-inflammatory brain syndromes provides a better understanding of etiology of its wide-array of symptoms and the wide array of conditions they can be seen in.

Emotions, immunity and sport: Winner and loser athlete's profile of fighting sport

Several studies have focused on the relationship between hormonal changes and affective states in sporting contexts relating to an agonistic outcome. More recently, pro-inflammatory cytokines have also been successfully associated with affective state modulation. The aim of this study was to investigate whether athletes who won or lost show different levels of steroid hormones (testosterone and cortisol), pro-inflammatory cytokine IL-1β, or expressions of anger and anxiety during six training fights in seasonal competitions down to the main seasonal competition. In 25 male kick-boxing athletes (age±SD, 28.68±5.34), anger states (RS score) and anxiety states (AS score) were assessed by STAXI-2 and STAI-Y, respectively. Cortisol (C), testosterone (T) and IL-1β salivary levels were measured by the ELISA method. The saliva samples were taken in the afternoon, 30min prior to the start and 30min from the end of both simulated and official competitions. The results showed that the RS score, T, T/C ratio salivary levels increased during the season, whereas the AS score, C and IL-1β suggested an opposite trend. Close to an official competition, the RS score, T, T/C ratio and IL-1β salivary concentrations were significantly higher, and then decreased during competition. By contrast, the AS score and C levels significantly increased throughout the official competition. In addition, significant differences were found for hormones and IL-1β concentrations as well as psychometric assessment close to the outcome of an official match. Athletes who lost showed an higher AS score and C level, while those who won were characterized by an higher level during the pre-competition RS score, T, T/C ratio, and IL-1β. Note that these factors were positively and significantly correlated at the pre-official competition time, while in a linear regression analysis, IL-1β, T and T/C ratio concentrations explained 43% of the variance in the RS score observed at the same time (adjusted R(2)=0.43, ANOVA P<.05). Our data suggest that the beginning of an agonistic event could trigger emotional responses which correspond to different biological processes instead that of a simulated fight. In particular, IL-1β could be a potential new biological marker of anger and the combined measurement of these factors may be a useful way of understanding athletes' change in relation to their performance.

Cerebrospinal fluid inflammatory cytokines and aggression in personality disordered subjects

BACKGROUND

Neurochemical studies have pointed to a modulatory role in human aggression for a variety of central neurotransmitters and neuromodulators such as cytokines. While animal studies of cytokines suggest an aggression-facilitating role for central cytokines, especially for interleukin-1β and other cytokines, no cerebrospinal fluid studies of cytokines have yet been reported in regard to human aggression.

METHODS

Basal lumbar cerebrospinal fluid samples were obtained from 38 physically healthy subjects with DSM-5 Personality Disorder and assayed for cerebrospinal fluid interleukin-6 (log IL-6) and cerebrospinal fluid soluble IL-1 Receptor II protein in the context of their relationship with measures of aggression.

RESULTS

Cerebrospinal fluid soluble interleukin-1 Receptor II (r=.35, r(2) = .12, P= .03), but not log interleukin-6 (r = -.05, r(2) = .00, P= .76), levels were positively correlated with a composite measure of aggression. Adding relevant covariates, including cerebrospinal fluid levels of serotonin and dopamine metabolites, to the statistical model doubled the strength of this relationship (partial r = .54, r(2) = .29, P= .002). No relationship was seen with history of suicidal behavior or with any measure of impulsivity, negative affectivity, or of general dimensions of personality.

CONCLUSION

These data suggest a positive relationship between at least one inflammatory cytokine in the central nervous system and aggression in human subjects. This finding adds to the complex picture of the central neurochemistry of impulsive aggression in human subjects.

Modulation of microglial function by the antidepressant drug venlafaxine

An increasing amount of data suggests that depression is an inflammatory disease. Depressed patients have higher peripheral blood levels of inflammatory markers which have been shown to access the brain and interact with the pathophysiological domain known to be involved in depression. Furthermore, microglia activation may play an important role in the inflammatory pathophysiology of depression.

In BV-2 microglia cell line, the present study investigated the potential anti-inflammatory effects of venlafaxine, along with its potential influence on injury of lipopolysaccharide (LPS)-stimulated cells. Although venlafaxine showed only marginal influence on the majority of the pro-inflammatory parameters assessed (in particular NO release, phagocytosis and proliferation), it significantly suppressed superoxide production by the stimulated cells. In addition, venlafaxine exerted also a protective effect on mitochondrial membrane potential and lysosomes of the stimulated microglia.

In conclusion, our results suggest that although VEN might have only a marginal effect on major pro-inflammatory parameters of microglia, its inhibitory effect on superoxide generation can contribute to the prevention of harmful effects of oxidative and nitrosative stress involved in the pathogenesis of depression. Moreover, the protective effect of VEN on viability of microglia can prevent a rapid reduction of these cells, thus avoiding limitations of several physiological processes in the brain and possibly also the progression of depression.

Depressogenic vulnerability and gender-specific patterns of neuro-immune dysregulation: What the ratio of cortisol to C-reactive protein can tell us about loss of normal regulatory control

We examined whether the ratio of cortisol (CORT) to high-sensitivity C-reactive protein (hsCRP), an index that captures the integrity of homeostatic regulation between the hypothalamic-pituitary-adrenal (HPA) axis and inflammatory processes, is associated with vulnerability to depression in a gender specific manner and whether glucocorticoid receptor (GR) sensitivity plays a role in these associations. Fasting blood samples were collected between 08:45 and 09:15 and assayed for CORT, hsCRP, and leukocyte count in 213 healthy, medication-free men and women. The NEO-Personality Inventory was used to assess neuroticism, extraversion and anxiety. We used the Hamilton Depression Interview to assess depressive symptoms, the Buss-Perry anger subscale to measure anger, and the Pittsburgh Sleep Quality Index to evaluate subjective sleep quality and its components. Log-transformed CORT/CRP values were analyzed using multiple regression with Holms' adjusted p-values and age, body mass index (BMI), and race as covariates. GR sensitivity was estimated using the log-transformed ratio of neutrophils (N)-to-monocytes (M). The log-transformed ratio of CORT/CRP did not differ between men and women but was significantly and negatively associated with age and BMI. Severity of depressive symptoms, extraversion, anxiety, and sleep quality were associated with the CORT/CRP ratio in a gender-specific manner. For women, decreasing CORT/CRP ratios, suggestive of an insufficient release of CORT coupled with a heightened inflammatory state, were associated with increasing severity of depressive symptoms, decreasing quality of sleep, increasing frequency of sleep disturbance, and decreasing extraversion. For men, increasing frequency of daytime disturbance and levels of anxiety were associated with increasing CORT/CRP ratio, suggestive of an enhanced release of CORT relative to attenuated levels of hsCRP. For both genders, increasing anger was associated with decreasing CORT/CRP ratios. Although results suggested GR downregulation in women but not men, such differences did not mediate the observed associations. With the use of the CORT/CRP ratio, we showed that vulnerability factors for depression are associated with a loss of normal regulatory controls resulting in gender-specific patterns of neuro-immune dysregulation. That GR downregulation did not influence these associations suggests that the loss of regulatory controls in at risk individuals is primarily at the level of the hormone. Beyond the individual contribution of each component of the CORT/CRP ratio, disruption of normal neuroimmune regulatory feedback provides a plausible biological framework useful in understanding biobehavioral vulnerabilities to depression in a gender specific manner. The CORT/CRP ratio may be a viable biomarker not only for delineating risk for MDD but also progression and treatment responses among patients with MDD; possibilities that are testable in future studies.

The Man I Once Knew

Grief, although traditionally conceptualized as a bereavement-related reaction, is also experienced by significant others in response to the profound cognitive and personality changes associated with a traumatic brain injury (TBI) in a loved one. Grief associated with the death of a loved one is related to increases in proinflammatory cytokines, yet it is not clear whether this is the case for grief experienced by individuals caring for a significant other with TBI. The purpose of this cross-sectional, exploratory study was to examine grief and its association with a proinflammatory cytokine, tumor necrosis factor α (TNF-α), in wives/partners caring for veterans with TBI. Participants completed written measures of grief, perceived stress, and depressive symptoms and provided morning saliva samples for TNF-α analysis. Participants reported levels of grief comparable to those reported in studies evaluating individuals grieving the death of a loved one. Path analysis revealed that grief was not associated with TNF-α; however, participants reporting high levels of blame/anger, a subscale of the grief scale, had higher levels of TNF-α. In addition, both grief and blame/anger were related to increased perceived stress and depressive symptoms; however, path analysis demonstrated that perceived stress and depressive symptoms did not mediate the influence of blame/anger on TNF-α. These findings suggest that blame/anger associated with grief may be related to the elevations in TNF-α exhibited by individuals caring for a loved one with TBI.

Inflammation and lithium: clues to mechanisms contributing to suicide-linked traits

Suicide is one of the leading causes of death in the United States, yet it remains difficult to understand the mechanistic provocations and to intervene therapeutically. Stress is recognized as a frequent precursor to suicide. Psychological stress is well established to cause activation of the inflammatory response, including causing neuroinflammation, an increase of inflammatory molecules in the central nervous system (CNS). Neuroinflammation is increasingly recognized as affecting many aspects of CNS functions and behaviors. In particular, much evidence demonstrates that inflammatory markers are elevated in traits that have been linked to suicidal behavior, including aggression, impulsivity and depression. Lithium is recognized as significantly reducing suicidal behavior, is anti-inflammatory and diminishes aggression, impulsivity and depression traits, each of which is associated with elevated inflammation. The anti-inflammatory effects of lithium result from its inhibition of glycogen synthase kinase-3 (GSK3). GSK3 has been demonstrated to strongly promote inflammation, aggressive behavior in rodents and depression-like behaviors in rodents, whereas regulation of impulsivity by GSK3 has not yet been investigated. Altogether, evidence is building supporting the hypothesis that stress activates GSK3, which in turn promotes inflammation, and that inflammation is linked to behaviors associated with suicide, including particularly aggression, impulsivity and depression. Further investigation of these links may provide a clearer understanding of the causes of suicidal behavior and provide leads for the development of effective preventative interventions, which may include inhibitors of GSK3.

Correlations of inflammatory gene pathways, corticolimbic functional activities, and aggression in pediatric bipolar disorder: a preliminary study

The mechanisms underlying aggression in adolescents with bipolar disorder have been poorly understood. The present study has investigated the associations among TNF gene expressions, functional brain activations under the frustrative non-reward task, and aggression in adolescents with bipolar disorder. Baseline gene expressions and aggressive tendencies were measured with the RNA-sequencing and Brief Rating of Aggression by Children and Adolescents (BRACHA), respectively. Our results show that activity levels of left subgenual anterior cingulate gyrus (ACG), right amygdala, left Brodmann area 10 (orbitofrontal cortex), and right thalamus were inversely correlated with BRACHA scores and were activated with frustrative non-reward during the affective Posner Task. In addition, 11 TNF related gene expressions were significantly correlated with activation of amygdala or ACG during the affective Posner Task. Three TNF gene expressions were inversely correlated with BRACHA score while one TNF gene (TNFAIP3) expression was positively correlated with BRACHA score. Therefore, TNF-related inflammatory cytokine genes may play a role in neural activity associated with frustrative non-reward and aggressive behaviors in pediatric bipolar disorder.

The relation between hostility and concurrent levels of inflammation is sex, age, and measure dependent

BACKGROUND AND OBJECTIVE

Hostility may be associated with greater systemic inflammation. However, contradictory evidence exists. Certain individuals or dimensions of hostility may be more susceptible to these effects. Main and interactive effects of hostility with sex and/or age were evaluated on markers of inflammation, independently of traditional risk factors for coronary artery disease.

METHODS

199 healthy men (81) and women (118), aged 20-64 years (M=41 ± 11 years) were recruited. Hostility was assessed using the Cook-Medley Hostility Inventory (CMHo) and ecological momentary assessments (EMA) of quarrelsome behavior and angry affect in daily living. Blood samples were drawn to measure inflammatory activity (Il-6, TNF-α, hsCRP, Il-8, Il-10, Il-18, MCP-1) and lipid oxidation (Myeloperoxidase; MPO). Correlations and hierarchical regression analyses were performed controlling for pertinent behavioral, psychological, medical, and socio-demographic factors.

RESULTS

Significant univariate associations emerged between CMHo and Il-6, TNF-α, MCP-1 (p<.05). Hierarchical regressions showed interactions of hostility with sex (Il-6, TNF-α; p<.05) and age (hsCRP, Il-6, TNF-α; p<.05). For example, in simple slope analyses, hostility was positively related to TNF-α in women (b=0.009, p=0.006) but not men. Greater hostility was also related to greater Il-6 levels among younger women (b=. 027, p=0.000).

CONCLUSION

Hostility, particularly cynical hostility, may be detrimental to (younger) women. The TNF-α, Il-6, CRP triad appears vulnerable to psychological and behavioral factors, and may be one mechanism by which cynical hostility (CMHo) contributes to increased cardiovascular risk in women. Prospective research is needed to verify this.

Relationship of trait anger and anger expression to C-reactive protein in postmenopausal women

Coronary heart disease (CHD) is the leading cause of death for women worldwide. Chronic inflammation and risk factors, such as obesity, smoking, and high cholesterol, are well-established risk factors for CHD. Little is known, however, about the mechanisms by which psychosocial factors, such as general anger proneness (trait anger) and anger expression style, may be associated with proinflammatory processes that contribute to cardiovascular morbidity and mortality in women. Our purpose in conducting this study was to examine the relationship of trait anger and anger expression to the proinflammatory biomarker C-reactive protein (CRP). A cross-sectional between-groups design was used to determine differences in serum levels of CRP in 42 American postmenopausal women, ages 45 to 65, who scored high on the selected anger characteristics, compared with women with lower scores. We did not find differences between high anger women and low anger women in mean levels of CRP, but we did find significant inverse relationships between CRP and some anger control characteristics. Specific health-promoting anger coping behaviors could minimize the deleterious effects of inflammatory responses in postmenopausal women.

Anger induced by interferon-alpha is moderated by ratio of arachidonic acid to omega-3 fatty acids

OBJECTIVE

Anger worsens in some patients during interferon-alpha (IFN-α) therapy. Elevated anger has also been associated with lower long-chain omega-3 (LCn-3) fatty acid levels. We examined whether fatty acids could influence vulnerability to anger during IFN-α exposure.

METHODS

Plasma arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) levels were determined prior to IFN-α therapy by mass spectroscopy. Repeated-measure analyses examined the relationship between AA/EPA+DHA and the subsequent development of labile anger and irritability in 82 subjects who prospectively completed the Anger, Irritability, and Assault Questionnaire (AIAQ) during the first eight weeks of IFN-α therapy.

RESULTS

Prior to IFN-α therapy, AA/EPA+DHA did not correlate with either labile anger or irritability. Pre-treatment AA/EPA+DHA did correlate with the subsequent maximal increase in labile anger during IFN-α therapy (r=0.33; p=0.005). Over time, labile anger increased more in subjects with above median AA/EPA+DHA ratios (p<0.05). Of the 17 subjects ultimately requiring psychiatric intervention for anger, 14/17 had above-median AA/EPA+DHA ratios (p=0.009). There was also an interaction with the tumor necrosis factor-alpha (TNF-α) promoter polymorphism (A-308G), such that only those with both elevated AA/EPA+DHA and the A allele had increased labile anger (p=0.001). In an additional 18 subjects, we conversely observed that selective serotonin reuptake inhibitor treatment was associated with increased irritability during IFN-α therapy.

CONCLUSION

LCn-3 fatty acid status may influence anger development during exposure to elevated inflammatory cytokines, and may interact with genetic risk for increased brain TNF-α. LCn-3 supplements may be one strategy for minimizing this adverse side effect of IFN-α.

Differential DNA methylation regions in cytokine and transcription factor genomic loci associate with childhood physical aggression

Background

Animal and human studies suggest that inflammation is associated with behavioral disorders including aggression. We have recently shown that physical aggression of boys during childhood is strongly associated with reduced plasma levels of cytokines IL-1α, IL-4, IL-6, IL-8 and IL-10, later in early adulthood. This study tests the hypothesis that there is an association between differential DNA methylation regions in cytokine genes in T cells and monocytes DNA in adult subjects and a trajectory of physical aggression from childhood to adolescence.

Methodology/Principal Findings

We compared the methylation profiles of the entire genomic loci encompassing the IL-1α, IL-6, IL-4, IL-10 and IL-8 and three of their regulatory transcription factors (TF) NFkB1, NFAT5 and STAT6 genes in adult males on a chronic physical aggression trajectory (CPA) and males with the same background who followed a normal physical aggression trajectory (control group) from childhood to adolescence. We used the method of methylated DNA immunoprecipitation with comprehensive cytokine gene loci and TF loci microarray hybridization, statistical analysis and false discovery rate correction. We found differentially methylated regions to associate with CPA in both the cytokine loci as well as in their transcription factors loci analyzed. Some of these differentially methylated regions were located in known regulatory regions whereas others, to our knowledge, were previously unknown as regulatory areas. However, using the ENCODE database, we were able to identify key regulatory elements in many of these regions that indicate that they might be involved in the regulation of cytokine expression.

Conclusions

We provide here the first evidence for an association between differential DNA methylation in cytokines and their regulators in T cells and monocytes and male physical aggression.

Childhood chronic physical aggression associates with adult cytokine levels in plasma

Background

An increasing number of animal and human studies are indicating that inflammation is associated with behavioral disorders including aggression. This study investigates the association between chronic physical aggression during childhood and plasma cytokine levels in early adulthood.

Methodology/Principal Findings

Two longitudinal studies were used to select males on a chronic physical aggression trajectory from childhood to adolescence (n = 7) and a control group from the same background (n = 25). Physical aggression was assessed yearly by teachers from childhood to adolescence and plasma levels of 10 inflammatory cytokines were assessed at age 26 and 28 years. Compared to the control group, males on a chronic physical aggression trajectory from childhood to adolescence had consistently lower plasma levels of five cytokines: lower pro-inflammatory interleukins IL-1α (T(28.7) = 3.48, P = 0.002) and IL-6 (T(26.9) = 3.76, P = 0.001), lower anti-inflammatory interleukin IL-4 (T(27.1) = 4.91, P = 0.00004) and IL-10 (T(29.8) = 2.84, P = 0.008) and lower chemokine IL-8 (T(26) = 3.69, P = 0.001). The plasma levels of four cytokines accurately predicted aggressive and control group membership for all subjects.

Conclusions/Significance

Physical aggression of boys during childhood is a strong predictor of reduced plasma levels of cytokines in early adulthood. The causal and physiological relations underlying this association should be further investigated since animal data suggest that some cytokines such as IL-6 and IL-1β play a causal role in aggression.

Varieties of anger and the inverse link between education and inflammation: toward an integrative framework

OBJECTIVE

To examine multiple aspects of anger experience and expression (frequency, outward expression, suppression, and control) as moderators of the association of social inequality, as measured by educational status, with inflammation and coagulation markers.

METHODS

After survey assessments via telephone and mail, Midlife in the United States respondents (N = 1054) participated in an overnight clinic visit, where they completed anger questionnaires and provided a fasting blood sample to measure interleukin-6 (IL-6), C-reactive protein (CRP), and fibrinogen.

RESULTS

Educational status was linked to higher anger control among men (B = 0.14, p = .001). Significant inverse correlations emerged between education and IL-6, CRP, and fibrinogen (r values ≥ -0.09, p values <.004) and between anger control and IL-6 and CRP (r values = -0.07, p values < .03). Controlling for demographic and health status covariates, anger-in predicted lower fibrinogen (p = .03). Interactions between education and anger measures were significant for education and trait anger as related to fibrinogen (p = .02) and education and anger-out as related to IL-6 (p = .05) and fibrinogen (p = .05). As predicted, the inverse relationships between education and IL-6 and fibrinogen were stronger among individuals reporting high anger. Anger control also moderated the association of education with IL-6 in women (p = .026), such that the link between education and IL-6 was attenuated among women with high anger control.

CONCLUSIONS

Varieties of anger moderated educational gradients in inflammation: The inverse relationships between education and inflammation markers were strongest among individuals with high anger and were attenuated among those with high anger control.

Central autonomic network mediates cardiovascular responses to acute inflammation: relevance to increased cardiovascular risk in depression?

Inflammation is a risk factor for both depression and cardiovascular disease. Depressed mood is also a cardiovascular risk factor. To date, research into mechanisms through which inflammation impacts cardiovascular health rarely takes into account central effects on autonomic cardiovascular control, instead emphasizing direct effects of peripheral inflammatory responses on endothelial reactivity and myocardial function. However, brain responses to inflammation engage neural systems for motivational and homeostatic control and are expressed through depressed mood state and changes in autonomic cardiovascular regulation. Here we combined an inflammatory challenge, known to evoke an acute reduction in mood, with neuroimaging to identify the functional brain substrates underlying potentially detrimental changes in autonomic cardiovascular control. We first demonstrated that alterations in the balance of low to high frequency (LF/HF) changes in heart rate variability (a measure of baroreflex sensitivity) could account for some of the inflammation-evoked changes in diastolic blood pressure, indicating a central (rather than solely local endothelial) origin. Accompanying alterations in regional brain metabolism (measured using (18)FDG-PET) were analysed to localise central mechanisms of inflammation-induced changes in cardiovascular state: three discrete regions previously implicated in stressor-evoked blood pressure reactivity, the dorsal anterior and posterior cingulate and pons, strongly mediated the relationship between inflammation and blood pressure. Moreover, activity changes within each region predicted the inflammation-induced shift in LF/HF balance. These data are consistent with a centrally-driven component originating within brain areas supporting stressor evoked blood pressure reactivity. Together our findings highlight mechanisms binding psychological and physiological well-being and their perturbation by peripheral inflammation.