Higher concentration of interleukin 6 - A possible link between major depressive disorder and childhood abuse

C-reactive protein across pregnancy in individuals exposed to childhood maltreatment: The role of psychological and physical sequelae of maltreatment

BACKGROUND

Childhood maltreatment (CM) has long-term consequences for the regulation of stress biology which are particularly pronounced when mental and physical health sequelae have manifested. C-reactive protein (CRP) has been shown to be elevated in the non-pregnant state in association with CM as well as in the setting of CM-associated mental and physical health sequelae. In pregnancy, however, the association between CM and CRP is less clear. We sought to examine this association and consider the moderating role of four common health sequelae of CM (maternal depressive symptoms, overweight/obesity, smoking, and hypertensive disorders during pregnancy).

METHODS

A prospective, longitudinal study of 744 healthy pregnant participants was conducted, with analyses focusing on a sample of 643 participants. CM was assessed with the Childhood Trauma Questionnaire (CTQ) and categorized by whether no vs. one or more moderate to severe CM experiences were reported. Blood serum concentrations of CRP, maternal depression severity (continuous scores of the Center for Epidemiologic Studies Depression Scale, CES-D) and smoking during pregnancy were assessed in early (16.52 ± 2.50 weeks gestation) and late (33.65 ± 1.18 weeks gestation) pregnancy. Pre-pregnancy body mass index (BMI) was obtained at the first study visit and hypertensive disorders diagnosed during pregnancy were obtained from the medical record. Linear mixed effects models were employed to assess main effects of CM as well as interactive effects of CM and four common CM-associated sequelae as well as a sum score of these sequelae on repeatedly measured CRP concentration. In secondary analyses, we conducted latent class analyses to classify participants based on their specific experiences of childhood abuse and/or neglect and to assess the association of these CM subgroups with CM sequelae and CRP. All analyses were adjusted for potential confounders (maternal race and ethnicity and education/income).

RESULTS

CRP concentration decreased from early to late pregnancy (B = -0.06, SE = 0.01, p < 0.001). While there was no main effect of CM on CRP (p = 0.49), the interaction of CM and depressive symptoms was associated with CRP concentration (B = 0.08, SE = 0.04, p < 0.05), indicating higher CRP across pregnancy with increasing levels of depressive symptoms during pregnancy in participants with CM experience. This interaction was mainly driven by participants with co-occurring physical and emotional maltreatment. For none of the other CM-associated sequelae a statistically significant interaction with CM on CRP concentration was observed.

CONCLUSIONS

These results add to the growing empirical evidence suggesting higher inflammation during pregnancy in participants exposed to CM who experience depressive symptoms and highlight the detrimental effects of multiple co-occurring experiences of maltreatment. Given the negative consequences of chronic inflammatory state for the mother and the developing fetus, monitoring and treating psychiatric sequelae during pregnancy among participants exposed to CM is potentially an important opportunity to dampen long-term detrimental effects of CM, serving at least two generations.

The relationship of peripheral blood cell inflammatory biomarkers and psychological stress in unmedicated major depressive disorder

BACKGROUND

Recent research has explored the linkage between major depressive disorder (MDD) and inflammation, especially via altered peripheral blood immune markers. However, the relationship between several novel leukocyte-derived ratios (LDR) and psychological stress in MDD remains uncertain. This study aimed to explore the relationship between LDR, clinical characteristics, recent life events, and childhood maltreatment in MDD patients.

METHODS

A cross-sectional case-control study was conducted involving 59 healthy controls (HC) and 50 unmedicated MDD patients. Subjects underwent psychological assessments and peripheral blood measurements. LDR assessed in this study included neutrophil-to-lymphocyte ratio (NLR), derived NLR (dNLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), white blood cell-to-mean platelet volume ratio (WMR), systemic immune inflammation index (SII), multiplication of neutrophil and monocyte counts (MNM), and systemic inflammation response index (SIRI).

RESULTS

MDD patients displayed significant alterations in WMR, PLR, and MNM compared to HC, as well as correlations between several LDR and various clinical features (duration of untreated psychosis and dNLR, the nine-item Patient Health Questionnaire and PLR, the 7-item Generalized Anxiety Disorder Questionnaire and SIRI (NLR and dNLR). There was a significant difference in the comparison of WMR in first-episode patients than in recurrent patients. Analyses further revealed an association between Life Event Scale total scores and NLR (dNLR). No correlation was found between Childhood Trauma Questionnaire total (or subscale) scores and LDR. Additionally, WMR and dNLR presented potential predictive value for distinguishing between MDD and HC.

CONCLUSION

The study concludes that MDD and some clinical features are associated with alterations in some peripheral blood LDR. These findings emphasize the potential role of peripheral blood LDR in the pathogenesis and clinical heterogeneity of MDD.

Inflammatory mediation of the relationship between early adversity and major depressive disorder: A systematic review

Early adverse experience is related to psychiatric illness that occurs decades later. The mechanisms underlying this phenomenon have not been fully identified. There is a translational and clinical literature linking early adversity with Major Depressive Disorder (MDD) and inflammation. We reviewed articles that examine whether inflammation mediates this relationship.

METHODS

Literature review of PUB MED, CINAHL and APA Psycinfo articles that explicitly examine inflammation as a mediator between early adversity and depression using ((((((((((adversity) OR (trauma)) OR (maltreatment)) OR (child abuse)) AND (inflammation)) OR (inflammatory cytokines)) OR (crp)) OR (il-6)) OR (tnf)) AND (mediates)) AND (depression))))))))) as key words.

RESULTS

2842 articles were initially identified. 1338 non-human studies were excluded and 512 more were filtered out as reviews. The remaining 992 titles and, when necessary, abstracts and manuscripts were reviewed and 956 were removed as being of other non-related phenomena. Four additional studies were added by hand searching the references of remaining studies. Out of these 40, 15 explicitly examined inflammation as a mediator of the relationship between early adversity and later depression. Approximately half (8/15) showed evidence that inflammation mediated the relationship between early adversity and depression. Sensitivity analyses showed that studies taking place in clinical populations, in youth and those that used the Adverse Childhood Events Scale to measure adversity, and IL-6 and TNF-α (as opposed to CRP) to measure inflammation were most likely to show mediation.

CONCLUSIONS

There is evidence to support the model of inflammation mediating the relationship between early adversity and depression. Certain measures in clinical populations appear more likely to support this model. Further study with more standardized, robust methods will help to answer this question more definitively and may elucidate a subtype of depression related to early adversity by alterations in immune function.

The association between victimization and inflammation: A meta-analysis

BACKGROUND

To meta-analyze the existing studies examining the association of childhood and adulthood victimization with inflammation and to explore the moderating variables that affect these relationships.

METHODS

Relevant work published before 28th February 2021 was identified by searching five major databases. We analyzed the cross-sectional data extracted from cross-sectional and longitudinal studies using the random-effects model to estimate the correlation (r) as the pooled effect size and further conducted subgroup analyses and sensitivity analyses.

RESULTS

A total of 37 articles finally met the inclusion criteria, including studies for C-reactive protein (CRP) (k = 23; N_CRP = 11,780), interleukin-6 (IL-6) (k = 31; N_IL-6 = 8943), and tumor necrosis factor-alpha (TNF-α) (k = 14; N_TNF-α = 4125). Overall, victimization has a significantly positive association with inflammation, with a small effect size (r = 0.122). Specifically, effect sizes were the largest for TNF-a (r = 0.152), followed by IL-6 (r = 0.119), and CRP (r = 0.084). Additionally, the effect sizes for victimization against children were r = 0.145 (k = 6) for childhood victimization - childhood inflammation, and r = 0.139 (k = 27) for childhood victimization - adulthood inflammation, which appear to be larger than that of victimization against adults (r = 0.039; k = 2).

LIMITATIONS

Only a small number of studies on adult victimization were included. In addition, we only analyzed the cross-sectional relationship and did not have sufficient data to compare different types of victimization and single vs. multiple victimizations.

CONCLUSIONS

Victimization is associated with a heightened inflammatory response. As victimization against children may have a stronger effect than victimization against adults, prevention of victimization targeting the childhood period may be necessary. Studies with more robust methodologies (i.e., representative, longitudinal, and multi-country designs) are needed to confirm these findings and to unpack the underlying mechanisms.

Impact of Childhood Adversity, as Early Life Distress, on Cytokine Alterations in Schizophrenia

Even though inflammation theory has been introduced in the pathophysiology of psychosis almost a century ago, many of its aspects have remained unelucidated. Numerous studies have shown cytokine dysregulation in schizophrenia and a predominance of pro-inflammatory cytokines, but on another side, various cytokines in a pro-inflammatory group have different trends in all subtypes of schizophrenia. Alterations are also present in anti-inflammatory and regulatory cytokines, but findings are still not consistent. On the other hand, it is well known that abuse and neglect in childhood may be predictors of psychotic disorders, and childhood adversity is also associated with alterations of the immune and inflammatory response (through various mechanisms including HPA dysregulation as well). This review aims to analyze conducted studies and elucidate the link between childhood abuse, schizophrenia, and cytokine alterations. Putting together this complex psycho-immunological puzzle for the subgroup of schizophrenia-diagnosed patients with distinct immunological abnormalities and a history of childhood abuse can help us to answer the question about the future treatment of these patients.

Childhood trauma and LPS-stimulated inflammation in adulthood: Results from the Netherlands Study of Depression and Anxiety

BACKGROUND

Childhood trauma (CT) is robustly associated with psychiatric disorders including major depressive and anxiety disorders across the life span. The innate immune system may play a role in the relation between CT and stress-related psychopathology. However, whether CT influences the innate production capacity of cytokine levels following ex vivo stimulation by lipopolysaccharide (LPS), is currently unknown.

METHODS

Using data from the Netherlands Study of Depression and Anxiety (NESDA, n=1237), we examined whether CT (emotional neglect, emotional, physical, and sexual abuse before the age of 16), assessed by the Childhood Trauma Interview, was associated with levels in supernatants of interferon (IFN)γ, interleukin-2 (IL-2), IL-4, IL-6, IL-8, IL-10, IL-18, monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1α, MIP-1β, matrix metalloproteinase-2 (MMP-2), TNFα and TNFβ after ex vivo stimulation with LPS. Cytokines were analysed individually and cumulatively (overall inflammation index and number of cytokines in high-risk quartile (HRQ)) using linear regression analyses.

RESULTS

After adjustment for demographic, lifestyle, and health-related covariates, total CT severity was associated with the overall inflammation index (β = 0.085, P_FDR = 0.011), the number of cytokines in HRQ (β = 0.063, P_FDR = 0.036), and individual markers of IL-2 (β = 0.067, P_FDR = 0.036), IL-6 (β = 0.091 P_FDR = 0.011), IL-8 (β = 0.085 P_FDR = 0.011), IL-10 (β = 0.094 P_FDR = 0.011), MCP-1 (β = 0.081 P_FDR = 0.011), MIP-1α (β = 0.061 P_FDR = 0.047), MIP1-β (β = 0.077 P_FDR = 0.016), MMP-2 (β = 0.070 P_FDR = 0.027), and TNFβ (β = 0.078 P_FDR = 0.016). Associations were strongest for individuals with severe CT, reporting multiple types or higher frequencies of trauma. Half of the findings persisted after adjustment for psychiatric status. The findings were consistent across different CT types.

CONCLUSION

Childhood Trauma is associated with increased LPS-stimulated cytokine levels, with evidence for a dose-response relationship. Our results highlight a dysregulated innate immune system capacity in adults with CT, which could contribute to an increased vulnerability for psychopathology and somatic disorders across the lifespan.

Epidemiology of Childhood Trauma and Analysis of Influencing Factors in Psychiatric Disorders Among Chinese Adolescents: A Cross-sectional Study

Childhood trauma (CT) can lead to long-term psychiatric disturbances. The current study investigated the prevalence of CT and its associated risk factors among Chinese adolescents with psychiatric disorders. Adolescents were recruited from a large study on mental health in the Hunan province of China in 2014. The study had a two-phase cross-sectional design. Patients with mental disorders (n = 907) and healthy subjects (n = 2,240) completed the Childhood Trauma Questionnaire-Short Form. Of all types of CT, emotional neglect (EN; 48.44%-68.82%) and physical neglect (PN; 60.0%-72.1%) were most common among adolescents. The experience of emotional abuse (EA), physical abuse (PA), sexual abuse (SA), EN, and multiple types of trauma (≥3) was higher among adolescents with psychiatric disorders than the healthy comparison group. Moreover, the results of logistic regression analysis showed that living in semi-urban areas and villages, having a sibling, and having bad-to-average academic performance were risk factors for CT among adolescents with psychiatric disorders (p < .05). In additional, the results of logistic regression analysis revealed that being a left-behind child and bad academic performance were risk factors for experiencing multiple types (≥3) of CT (p < .05), while being female and having siblings were found to be protective factors against (≥3) CT (p < .05). In summary, the prevalence rate of CT (especially multiple types of trauma) is high among adolescents with psychiatric disorders. These results indicate the importance of reducing CT to limit the likelihood of psychiatric disorders, especially among adolescents.

Exposure to childhood maltreatment and systemic inflammation across pregnancy: The moderating role of depressive symptomatology

BACKGROUND

Childhood maltreatment (CM) has long-term consequences for dysregulation of the immune system which is particularly pronounced when mental and physical health sequelae have manifested. Higher proinflammatory state has been shown in non-pregnant state in association with CM as well as with depression, one of the most frequent and pernicious psychiatric sequelae of CM. During pregnancy, however, this association is less clear. Given the important role of maternal inflammatory state during pregnancy for fetal, pregnancy, and birth outcomes, we sought to examine the association between CM and proinflammatory state during pregnancy considering the moderating role of maternal depressive symptoms characterized serially across pregnancy.

METHODS

A prospective, longitudinal study of 180 healthy pregnant women was conducted with serial assessments in early (12.98 ± 1.71 weeks gestation), mid (20.53 ± 1.38 weeks gestation) and late (30.42 ± 1.4 weeks gestation) pregnancy. Maternal history of CM was assessed with the Childhood Trauma Questionnaire (CTQ) and the total score was used as an indicator of CM experience. Maternal depressive symptoms were assessed at each pregnancy visit with the Center for Epidemiologic Studies Depression Scale (CES-D). Serum concentrations of tumor necrosis factor (TNF)-α and interleukin (IL)-6 were obtained at each pregnancy visit and combined to a composite maternal proinflammatory score. Linear mixed effects models were employed to assess the association between CTQ score, CES-D score, and proinflammatory score during pregnancy, adjusting for potential confounders.

RESULTS

Gestational age was associated with the proinflammatory score (B = 0.02; SE = 0.00; p < .001), indicating an increase in inflammation across gestation. Neither CTQ score nor depressive symptoms were independently associated with the proinflammatory score (ps > 0.28). However, the interaction between CTQ score and depressive symptoms was associated with the proinflammatory score (B = 0.03, SE = 0.01, p < .05), indicating higher inflammation across pregnancy with increasing levels of depressive symptoms during pregnancy in women with higher CTQ scores. Exploratory analyses suggested that this interaction was mainly driven by CTQ subscale scores assessing experiences of abuse rather than neglect.

CONCLUSIONS

These findings suggest a moderating role of maternal depressive symptoms during pregnancy on the association of early life stress with inflammation and thus highlight the importance of the timely assessment of both CM exposure and depressive symptoms which might allow for the development of targeted and individualized interventions to impact inflammation during pregnancy and to ameliorate the detrimental long-term effects of CM. The current findings add to a better understanding of the prenatal biological pathways that may underlie intergenerational transmission of maternal CM.

The Effects of Rosiglitazone on Task Specific Anxiety-Like Behavior and Novelty Seeking in a Model of Chronic Adolescent Unpredictable Stress

Adolescence is characterized as a period of increased social behavior, risk taking, and novelty seeking, partly due to ongoing maturation in critical brain areas and the hypothalamic-pituitary-adrenal (HPA) negative-feedback system. During this period there is heightened vulnerability to stress that can drive neuro-immune-endocrine remodeling, resulting in the emergence of maladaptive behaviors that increase susceptibility to alcohol and substance abuse. Here we used a rat model to investigate the impact of chronic adolescent unpredictable stress on a battery of behavioral measures to assess anxiety, novelty seeking, risk taking, depression, and voluntary ethanol consumption while determining whether the PPARγ agonist rosiglitazone can attenuate these effects. Adolescent female rats that experienced stress showed increased risk taking behavior and novelty seeking behavior with no change in ethanol consumption. The administration of rosiglitazone during stress induction attenuated stress-induced cortisol elevation, normalized risk taking behavior in a model anxiety, and attenuated novelty seeking in a task-specific manner. Depressive-like behavior was not impacted by adolescent unpredictable stress or the administration of rosiglitazone. The results from this study demonstrate that exposure to unpredictable stress during adolescence increases the prevalence of maladaptive behaviors that are known to increase susceptibility to alcohol and substance abuse, and that rosiglitazone may be an effective therapeutic to attenuate the emergence of select risk taking and novelty seeking behaviors in females.

Evaluation of inflammatory and metabolic impairments regarding depression dimensions: a case control study

Background

Patients with depression are at a higher risk of developing serious medical problems such as diabetes mellitus, hypertension, and cardiovascular diseases, increasing the burden of depression and worsening its outcome.

Recent studies revealed the presence of low-grade systemic inflammation and metabolic impairments which are playing an important role in the development of these medical problems among patients with depression.

It should be noted that not all patients with depressive disorder have these immune or metabolic impairments.

The study aims to evaluate inflammatory and metabolic impairments among patients with depression through categorizing patients with depression into four dimensional profilers which are (1) atypical energy-related symptom dimension, (2) melancholic dimension, (3) childhood trauma dimension, and (4) anxious distress dimension.

Also, the current study will evaluate inflammatory and metabolic impairments among patients with depression and a control group.

Results

This study highlights that of the patients with metabolic impairments (including hypertension, impaired glycemic control, low/high-density lipoprotein, elevated triglycerides, and central obesity), all of them had reported significantly higher scores in the atypical, energy-related symptom dimension.

Also, patients with impaired glycemic control had reported significantly (p < 0.001) high scores in the anxious distress symptom dimension.

While patients with inflammatory impairment (serum CRP > 3 mg/L) had significantly (p = 0.009) reported higher scores in the childhood trauma symptom dimension.

In addition, statistically significant metabolic and inflammatory impairments are detected among the depression cases group in comparison with the control group.

Conclusions

This study found that patients with depression presented by atypical, energy-related symptoms were at a higher risk of metabolic impairments than other depression profilers.

Also, patients of the Anxious distress symptom dimension reported significant impaired glycemic control.

In addition, patients with depression of the childhood trauma dimension were associated with high levels of inflammatory marker (C-reactive protein).

Potential implications

These results can be applied clinically to improve treatment and prognosis in patients with depression. For example, depressed patients with atypical, energy-related symptoms should increase their daily physical activities and exercise, and they should follow a special diet. Also, anti-inflammatory medications could be added to depressed patients of the childhood trauma dimension.

Inflammation and early life stress: An updated review of childhood trauma and inflammatory markers in adulthood

Inflammation, as a neurobiological consequence of childhood trauma, has frequently been reported across research, however, recent investigations suggest this relationship may be dependent on specificities such as type of trauma, type of inflammatory marker, and additional mediatory variables - such as body mass index (BMI), age, and sex. As an updated version of a previous review by Baumeister et al., the current review comprised a search of PubMed, which identified 37 articles that collectively assessed 4 inflammatory markers (CRP, IL-6, TNFα and IL-1β). A review of the studies revealed predominantly non-significant associations between childhood trauma and elevated levels of all inflammatory markers in adulthood. However, in line with previous research, discrepancies in significance arose when considering type of trauma, type of inflammatory marker, and additional variables. Compared to neglect, abuse showed greater significant associations with elevated inflammatory markers in adulthood, though this was dependent on the individual subtypes (emotional, physical or sexual). Mediation analyses reported BMI as a significant mediator, though, when controlled for, no significant differences were found. Sex differences were reported but investigations were sparse. Future research should investigate the mediatory role of sex differences in the inflammatory effects of childhood trauma. Many studies in the review were restricted by use of the same trauma measure - the Childhood Trauma Questionnaire. To assess greater variety of trauma types, future studies should utilize other standardized measures to explore these avenues.

Childhood maltreatment correlates with higher concentration of transforming growth factor beta (TGF-β) in adult patients with major depressive disorder

Transforming growth factor beta (TGF-β), which has a role as a regulatory cytokine, has not been widely investigated in patients with major depressive disorder (MDD) who experienced childhood trauma. The aim of our study was to investigate the differences in circulating TGF-β levels between the patients with major depressive disorder (MDD) with and without child maltreatment (CM) history, and to compare them to the corresponding control subjects' groups (with or without CM). Blood samples were obtained from 55 patients, fulfilling DSM-IV-R criteria for a current MDD episode without psychotic symptoms, and 45 healthy controls, matched for age and gender. Participants were administered the Childhood Trauma Questionnaire (CTQ). Serum TGF-β concentration was determined by enzyme-linked immunosorbent assay. The concentration of TGF-β was significantly higher in patients with MDD with CM history, compared to MDD patients with no CM, as well as both control groups. Furthermore, we have shown that the combined effect of CM history and MDD affected TGF-β levels in adulthood, which was not observed in the control group with CM. These results indicate that MDD patients with the experience of CM have altered immune-regulatory response, and they may constitute a specific subtype within this heterogenic disorder (ecophenotype).

The lipid paradox in neuroprogressive disorders: Causes and consequences

Chronic systemic inflammation is associated with an increased risk of cardiovascular disease in an environment of low low-density lipoprotein (LDL) and low total cholesterol and with the pathophysiology of neuroprogressive disorders. The causes and consequences of this lipid paradox are explored. Circulating activated neutrophils can release inflammatory molecules such as myeloperoxidase and the pro-inflammatory cytokines interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha. Since activated neutrophils are associated with atherosclerosis and cardiovascular disease and with major depressive disorder, bipolar disorder and schizophrenia, it seems reasonable to hypothesise that the inflammatory molecules released by them may act as mediators of the link between systemic inflammation and the development of atherosclerosis in neuroprogressive disorders. This hypothesis is tested by considering the association at a molecular level of systemic inflammation with increased LDL oxidation; increased small dense LDL levels; increased lipoprotein (a) concentration; secretory phospholipase A₂ activation; cytosolic phospholipase A₂ activation; increased platelet activation; decreased apolipoprotein A1 levels and function; decreased paroxonase-1 activity; hyperhomocysteinaemia; and metabolic endotoxaemia. These molecular mechanisms suggest potential therapeutic targets.

The association of child maltreatment and systemic inflammation in adulthood: A systematic review

Introduction

Child maltreatment (CM) is associated with mental and physical health disorders in adulthood. Some studies have identified elevated markers of systemic inflammation in adult survivors of CM, and inflammation may mediate the association between CM and later health problems. However, there are methodological inconsistencies in studies of the association between CM and systemic inflammation and findings are conflicting. We performed a systematic review to examine the association of CM with systemic inflammation in adults.

Methods

A pre-registered systematic review was performed following PRISMA guidelines. Medline, Embase, Scopus and PsychInfo were searched for studies of the association of CM with blood markers of inflammation in adults. Quality was assessed using the Crowe Critical Appraisal Tool. We had intended to perform a meta-analysis, but this was not possible due to variation in study design and reporting.

Results

Forty-four articles met criteria for inclusion in the review. The most widely reported biomarkers were C-Reactive Protein (CRP) (n = 27), interleukin-6 (IL-6) (n = 24) and Tumour Necrosis Factor-alpha (TNF-a) (n = 17). Three studies were prospective (all relating to CRP) and the remainder were retrospective. 86% of studies were based in high income countries. In the prospective studies, CM was associated with elevated CRP in adulthood. Results of retrospective studies were conflicting. Methodological issues relating to the construct of CM, methods of analysis, and accounting for confounding or mediating variables (particularly Body Mass Index) may contribute to the uncertainty in the field.

Conclusions

There is some robust evidence from prospective studies that CM is associated with elevated CRP in adulthood. We have identified significant methodological inconsistencies in the literature and have proposed measures that future researchers could employ to improve consistency across studies. Further prospective, longitudinal, research using robust and comparable measures of CM with careful consideration of confounding and mediating variables is required to bring clarity to this field.

Biological correlates of early life stressful events in major depressive disorder

Major depressive disorder (MDD) is the most common psychiatric disorder and responds for important psychosocial consequences. Stressful life events, especially early life stress (ELS), contribute to an increased probability to develop MDD, leading in particular to severe and chronic manifestation and unfavorable treatment outcome. The association between ELS and MDD seems to have biological bases, consisting in dysregulations occurring at different levels. The aim of this narrative review is to propose an overview of the literature ranging from genetic, epigenetic, expression and protein to neuroimaging correlates underlying this relationship. A search on Pubmed of studies assessing biological correlates of ELS in MDD development, focusing on human studies conducted in both peripheral and brain tissues, was performed. Evidence indicated that the hypothalamic-pituitary-adrenal (HPA) axis and the serotonergic, dopaminergic, neurotrophin and oxytocin systems might play a role in the mediation between ELS and MDD. The most consistent results were found for genetic and epigenetic studies and indicated a joint involvement of the systems mentioned. Expression studies are less numerous and point to an involvement of stress-related systems. Concerning protein studies, the main mediators are markers related to the inflammatory and immune systems. Neuroimaging studies aiming at evaluating brain alterations connecting ELS and MDD in relation to biomarkers indicated the hippocampus, the amygdala and the frontal cortex as important anatomical mediators. These findings can build the bases for future research and clinical interventions; indeed, the clarification of biological mechanisms mediating the relationship between ELS and MDD can lead to new and individualized preventive and therapeutic possibilities.

Prevalence of childhood trauma among adults with affective disorder using the Childhood Trauma Questionnaire: A meta-analysis

BACKGROUND

Childhood trauma is associated with major depressive disorder (MDD) and bipolar disorder (BD) in adults. However, no meta-analysis was performed on the prevalence of different types of childhood trauma in adults with affective disorders, using the Childhood Trauma Questionnaire (CTQ).

METHODS

Four databases were used to search articles regarding the prevalence of childhood emotional abuse (CEA), childhood physical abuse (CPA), childhood sexual abuse (CSA), childhood physical neglect (CPN), and childhood emotional neglect (CEN) in patients with MDD and BD using the CTQ.

RESULTS

A total of 17 and 11 articles were found analyzing patients with MDD and BD, respectively. A pooled prevalence rate of 33.0% and 30.0% for CEA, 17.0% and 18.0% for CPA, 19.0% and 22.0% for CSA, 37.0% and 31.0% for CEN, and 31% and 30.0% for CPN was found in patients with MDD and BD respectively. A difference in 95% confidence interval in the CSA rate between men and women was found in patients with MDD in the gender subgroup and in the rate of some types of childhood trauma in the continent subgroup in both patient types.

LIMITATIONS

A limited number of articles were included in some continents, thus, the heterogeneity in the meta-analysis was generally high.

CONCLUSION

The prevalence of CEA, CEN, and CPN in patients with affective disorders was relatively high, whereas that of CPA and CSA was relatively low. These childhood traumas might be affected by continent and gender.

Depression profilers and immuno-metabolic dysregulation: Longitudinal results from the NESDA study

BACKGROUND

Major depressive disorder (MDD) is linked to higher cardio-metabolic comorbidity that may in part be due to the low-grade inflammation and poorer metabolic health observed in MDD. Heterogeneity of MDD is however large, and immune-inflammatory and metabolic dysregulation is present in only part of the MDD cases. We examined the associations of four depression dimensional profilers (atypical energy-related symptom dimension, melancholic symptom dimension, childhood trauma severity, and anxious distress symptom dimension) with immuno-metabolic outcomes, both cross-sectionally and longitudinally.

METHODS

Three waves covering a 6-year follow-up (>7000 observations) of the Netherlands Study of Depression and Anxiety (NESDA) were used. Depression profilers were based on the Inventory of Depressive Symptomatology, the Beck Anxiety Inventory, and the Childhood Trauma index. An inflammatory index (based on IL-6 and CRP), a metabolic syndrome index (based on the five metabolic syndrome components), and a combination of these two indices were constructed. Mixed models were used for cross-sectional and longitudinal models, controlling for covariates.

RESULTS

Of the four depression profilers, only the atypical, energy-related symptom dimension showed robust associations with higher scores on the inflammatory, metabolic syndrome and combined inflammatory-metabolic indexes cross-sectionally, as well as at follow-up. The melancholic symptom dimension was associated with lower scores on the metabolic syndrome index both cross-sectionally and longitudinally.

CONCLUSION

The atypical energy-related symptom dimension was linked to poorer immune-inflammatory and metabolic health, while the melancholic symptom dimension was linked to relatively better metabolic health. Persons with high atypical energy-related symptom burden, representing an immuno-metabolic depression, may be the most important group to target in prevention programs for cardiometabolic disease, and may benefit most from treatments targeting immuno-metabolic pathways.

The Association Between Adverse Childhood Experiences and Inflammation in Patients with Major Depressive Disorder: A Systematic Review

BACKGROUND

Replicated evidence has documented elevated levels of pro-inflammatory cytokines in populations with major depressive disorder (MDD). However, childhood trauma, a risk factor for MDD, has been separately shown to also impact inflammatory systems; its potential moderating effect on inflammation in MDD has been less frequently investigated.

METHODS

We systematically searched the PubMed, Google Scholar, Scopus, Web of Science, and PsycINFO databases between database inception to June 19th, 2019 using the search string: (Childhood trauma or Adverse childhood experiences or childhood abuse or childhood rape or physical abuse or emotional abuse) AND (Inflammation or inflammatory cytokines or interleukin-6 or tumor necrosis factor-alpha or c-reactive protein) AND (Major Depressive Disorder or Depression).

RESULTS

We identified nine articles that evaluated inflammatory biomarkers in MDD populations with adverse childhood experiences (ACE). Eight articles evaluated IL-6, three articles evaluated CRP, and five articles evaluated TNF-α. The strongest effects were observed for IL-6; six studies reported significantly elevated levels of IL-6 in MDD and ACE patients compared to healthy controls and/or MDD-only populations. Meanwhile, only three studies found TNF-α to be significantly elevated in the MDD and ACE cohort. In contrast, MDD-ACE populations did not exhibit significantly elevated CRP.

LIMITATIONS

The methodological heterogeneity amongst studies was very high.

CONCLUSION

The current review suggests that MDD and ACE subpopulations present elevated levels of IL-6 compared to MDD-only and healthy control populations. Therefore, research should consider whether elevated inflammation in MDD is just an epiphenomenon of previous ACE and whether MDD-ACE subgroups are more likely to respond to immune-inflammatory targeted intervention.

Inflammatory markers in depression: A meta-analysis of mean differences and variability in 5,166 patients and 5,083 controls

IMPORTANCE

The magnitude and variability of cytokine alterations in depression are not clear.

OBJECTIVE

To perform an up to date meta-analysis of mean differences of immune markers in depression, and to quantify and test for evidence of heterogeneity in immune markers in depression by conducting a meta-analysis of variability to ascertain whether only a sub-group of patients with depression show evidence of inflammation.

DATA SOURCES

Studies that reported immune marker levels in peripheral blood in patients with depression and matched healthy controls in the MEDLINE database from inception to August 29th 2018 were examined.

STUDY SELECTION

Case-control studies that reported immune marker levels in peripheral blood in patients with depression and healthy controls were selected.

DATA EXTRACTION AND SYNTHESIS

Means and variances (SDs) were extracted for each measure to calculate effect sizes, which were combined using multivariate meta-analysis.

MAIN OUTCOMES AND MEASURES

Hedges g was used to quantify mean differences. Relative variability of immune marker measurements in patients compared with control groups as indexed by the coefficient of variation ratio (CVR).

RESULTS

A total of 107 studies that reported measurements from 5,166 patients with depression and 5,083 controls were included in the analyses. Levels of CRP (g = 0.71; 95%CI: 0.50-0.92; p < 0.0001); IL-3 (g = 0.60; 95%CI: 0.31-0.89; p < 0.0001); IL-6 (g = 0.61; 95%CI: 0.39-0.82; p < 0.0001); IL-12 (g = 1.18; 95%CI: 0.74-1.62; p < 0.0001); IL-18 (g = 1.97; 95%CI: 1.00-2.95; p < 0.0001); sIL-2R (g = 0.71; 95%CI: 0.44-0.98; p < 0.0001); and TNFα (g = 0.54; 95%CI: 0.32-0.76; p < 0.0001) were significantly higher in patients with depression. These findings were robust to a range of potential confounds and moderators. Mean-scaled variability, measured as CVR, was significantly lower in patients with depression for CRP (CVR = 0.85; 95%CI: 0.75-0.98; p = 0.02); IL-12 (CVR = 0.61; 95%CI: 0.46-0.80; p < 0.01); and sIL-2R (CVR = 0.85; 95%CI: 0.73-0.99; p = 0.04), while it was unchanged for IL-3, IL-6, IL-18, and TNF α.

CONCLUSIONS AND RELEVANCE

Depression is confirmed as a pro-inflammatory state. Some of the inflammatory markers elevated in depression, including CRP and IL-12, show reduced variability in patients with depression, therefore supporting greater homogeneity in terms of an inflammatory phenotype in depression. Some inflammatory marker elevations in depression do not appear due to an inflamed sub-group, but rather to a right shift of the immune marker distribution.

From early adversities to immune activation in psychiatric disorders: the role of the sympathetic nervous system

Increased peripheral levels of cytokines and central microglial activation have been reported in patients with psychiatric disorders. The degree of both innate and adaptive immune activation is also associated with worse clinical outcomes and poor treatment response in these patients. Understanding the possible causes and mechanisms leading to this immune activation is therefore an important and necessary step for the development of novel and more effective treatment strategies for these patients. In this work, we review the evidence of literature pointing to childhood trauma as one of the main causes behind the increased immune activation in patients with psychiatric disorders. We then discuss the potential mechanisms linking the experience of early life adversity (ELA) to innate immune activation. Specifically, we focus on the innervation of the bone marrow from sympathetic nervous system (SNS) as a new and emerging mechanism that has the potential to bridge the observed increases in both central and peripheral inflammatory markers in patients exposed to ELA. Experimental studies in laboratory rodents suggest that SNS activation following early life stress exposure causes a shift in the profile of innate immune cells, with an increase in proinflammatory monocytes. In turn, these cells traffic to the brain and influence neural circuitry, which manifests as increased anxiety and other relevant behavioural phenotypes. To date, however, very few studies have been conducted to explore this candidate mechanism in humans. Future research is also needed to clarify whether these pathways could be partially reversible to improve prevention and treatment strategies in the future.

The cytokine network in the pathogenesis of major depressive disorder. Close to translation?

Major depressive disorder (MDD) is a common condition that afflicts the general population across a broad spectrum of ages and social backgrounds. MDD has been identified by the World Health Organization as a leading cause of disability worldwide. Approximately 30% of patients are poor responsive to standard of care (SOC) treatment and novel therapeutic approaches are warranted. Since chronic inflammation, as it is often observed in certain cancers, type 2 diabetes, psoriasis and chronic arthritis, are accompanied by depression, it has been suggested that immunoinflammatory processes may be involved in the pathogenesis of MDD. Cytokines are a group of glycoproteins secreted from lymphoid and non-lymphoid cells that orchestrate immune responses. It has been suggested that a dysregulated production of cytokines may be implicated in the pathogenesis and maintenance of MDD. On the basis of their functions, cytokines can be subdivided in pro-inflammatory and anti-inflammatory cytokines. Since abnormal blood and cerebrospinal fluid of both pro and anti-inflammatory cytokines are altered in MDD, it has been suggested that abnormal cytokine homeostasis may be implicated in the pathogenesis of MDD and possibly to induction of therapeutic resistance. We review current data that indicate that cytokines may represent a useful tool to identify MDD patients that may benefit from tailored immunotherapeutic approaches and may represent a potential tailored therapeutic target.

Enhanced noradrenergic activity by yohimbine and differential fear conditioning in patients with major depression with and without adverse childhood experiences

Major depressive disorder (MDD) has been associated with changes in the biological stress systems, including the locus coeruleus-noradrenergic system. Accumulated evidence suggests an upregulation of central alpha2-receptors, leading to decreased noradrenergic activity on a central level in MDD patients. Adverse childhood experiences (ACE) such as physical or sexual abuse might contribute to those changes. Furthermore, noradrenaline can affect cognitive processes, e.g. learning and memory. Cognitive dysfunctions constitute an important symptom of MDD. We aimed to investigate the relationship of alpha2-receptor dysregulation with learning processes in MDD by conducting a differential fear conditioning paradigm after double-blind administration of the alpha2-receptor antagonist yohimbine versus placebo. To investigate the role of ACE systematically, we included four groups of healthy participants and MDD patients with and without ACE (MDD-/ACE-: N = 44, MDD-/ACE+: N = 26, MDD+/ACE-: N = 24, MDD+/ACE+: N = 24; without antidepressant medication). We found increased noradrenergic activity after yohimbine administration across groups as measured by alpha-amylase and blood pressure. Overall, fear responses were higher after yohimbine as indicated by skin conductance responses and fear-potentiated startle responses. While we found no significant MDD effect, ACE had significant impact on the ability to discriminate between both conditioned stimuli (CS+ predicting an aversive stimulus, CS- predicting none), depending on drug condition. After yohimbine, CS discrimination decreased in individuals without ACE, but not in individuals with ACE. Differences in the response to yohimbine might be explained by aberrant alpha2-receptor regulation in individuals with ACE. Impaired discrimination of threat and safety signals might contribute to enhanced vulnerability following ACE.

Plasma microRNA Array Analysis Identifies Overexpressed miR-19b-3p as a Biomarker of Bipolar Depression Distinguishing From Unipolar Depression

OBJECTIVES

The clinical characteristics of bipolar disorder (current major depressive episode) (BD) overlap with unipolar depressive disorder (UD), which makes it difficult to perform an accurate diagnosis. We identified plasma microRNAs (miRNAs) that distinguished BD from UD and explored the relationship between miRNA expression levels and clinical characteristics.

METHODS

Total miRNAs from blood plasma from seven UD patients, seven BD patients, and six controls were analyzed. The identified miRNAs were validated in a separate population group. Depression severity and early life adversities were assessed. Bioinformatic analysis was conducted to investigate the target genes that were identified and the pathways associated with the altered miRNAs.

RESULTS

Compared to controls, 42 miRNAs were differentially expressed in patients. miR-19b-3p, miR-3921, and miR-1180-3p were selected to validate the microarray results. Only miR-19b-3p was validated as down-regulated in patients. The primary predicted genes associated with miR-19b-3p were MAPK1, PTEN, and PRKAA1. The most relevant KEGG pathways included mTOR, FoxO, and the PI3-K/Akt signaling pathway. BD patients were more likely to have higher expression levels of miR-19b-3p and more severe childhood trauma experience compared to UD patients.

CONCLUSIONS

Plasma miR-19b-3p is a potential non-invasive biomarker that might be useful in distinguishing UD from BD. miR-19b3p was predicted to be involved in the pathway of inflammatory dysregulation associated with experiencing early childhood trauma.

Gut microbiota-brain axis in depression: The role of neuroinflammation

Major depressive disorder (MDD) is a psychiatric condition that affects a large number of people in the world, and the treatment existents do not work for all individuals affected. Thus, it is believed that other systems or pathways which regulate brain networks involved in mood regulation and cognition are associated with MDD pathogenesis. Studies in humans and animal models have been shown that in MDD there are increased levels of inflammatory mediators, including cytokines and chemokines in both periphery and central nervous system (CNS). In addition, microglial activation appears to be a key event that triggers changes in signaling cascades and gene expression that would be determinant for the onset of depressive symptoms. Recent researches also point out that changes in the gut microbiota would lead to a systemic inflammation that in different ways would reach the CNS modulating inflammatory pathways and especially the microglia, which could influence responses to treatments. Moreover, pre- and probiotics have shown antidepressant responses and anti-inflammatory effects. This review will focus on studies that show the relationship of inflammation with the gut microbiota-brain axis and its relation with MDD.

Epigenetic Modifications in Stress Response Genes Associated With Childhood Trauma

Adverse childhood experiences (ACEs) may be referred to by other terms (e.g., early life adversity or stress and childhood trauma) and have a lifelong impact on mental and physical health. For example, childhood trauma has been associated with posttraumatic stress disorder (PTSD), anxiety, depression, bipolar disorder, diabetes, and cardiovascular disease. The heritability of ACE-related phenotypes such as PTSD, depression, and resilience is low to moderate, and, moreover, is very variable for a given phenotype, which implies that gene by environment interactions (such as through epigenetic modifications) may be involved in the onset of these phenotypes. Currently, there is increasing interest in the investigation of epigenetic contributions to ACE-induced differential health outcomes. Although there are a number of studies in this field, there are still research gaps. In this review, the basic concepts of epigenetic modifications (such as methylation) and the function of the hypothalamic-pituitary-adrenal (HPA) axis in the stress response are outlined. Examples of specific genes undergoing methylation in association with ACE-induced differential health outcomes are provided. Limitations in this field, e.g., uncertain clinical diagnosis, conceptual inconsistencies, and technical drawbacks, are reviewed, with suggestions for advances using new technologies and novel research directions. We thereby provide a platform on which the field of ACE-induced phenotypes in mental health may build.

Evaluation of Serum Interleukin-6 and C-reactive Protein Levels in Drug-naïve Major Depressive Disorder Patients

Background Major depressive disorder (MDD) is a disabling health problem with a very high global prevalence and burden. Alteration of inflammatory markers in depression is of growing interest to many psychiatry researchers. This study aimed to examine the serum levels of interleukin-6 (IL-6) and C-reactive protein (CRP) in MDD patients to find out their association with depression. Materials and methods The present study recruited 88 MDD patients and 86 control subjects matched by age, gender, and body mass index (BMI). The Hamilton depression rating scale (Ham-D) was used on all patients to measure their severity of depression. Serum levels of IL-6 and CRP were analyzed by commercially available enzyme-linked immunosorbent assay (ELISA) kits (Abcam, Cambridge, MA, USA). Results The mean values of serum levels of IL-6 and CRP were 2.94 ± 0.12 pg/mL and 0.99 ± 0.02 mg/L for the patient group and 2.42 ± 0.21 pg/mL and 1.09 ± 0.06 mg/L for the control group, respectively. We found significantly elevated concentrations of serum IL-6 in MDD patients compared with control subjects (p < 0.001). However, the alteration of serum CRP levels was not significant between the groups (p = 0.126). Ham-D scores of patients were positively correlated with serum IL-6 (r = 0.552; p = 0.004) and CRP (r = 0.621; p < 0.001) levels. Moreover, serum IL-6 and CRP levels were observed to be positively correlated (r = 0.452; p = 0.043) with each other in depression. Conclusions The present study suggests that increased serum IL-6 level might be a contributing factor to the pathogenesis of depression.

Early life stress, air pollution, inflammation, and disease: An integrative review and immunologic model of social-environmental adversity and lifespan health

Socially disadvantaged individuals are at greater risk for simultaneously being exposed to adverse social and environmental conditions. Although the mechanisms underlying joint effects remain unclear, one hypothesis is that toxic social and environmental exposures have synergistic effects on inflammatory processes that underlie the development of chronic diseases, including cardiovascular disease, diabetes, depression, and certain types of cancer. In the present review, we examine how exposure to two risk factors that commonly occur with social disadvantage-early life stress and air pollution-affect health. Specifically, we identify neuroimmunologic pathways that could link early life stress, inflammation, air pollution, and poor health, and use this information to propose an integrated, multi-level model that describes how these factors may interact and cause health disparity across individuals based on social disadvantage. This model highlights the importance of interdisciplinary research considering multiple exposures across domains and the potential for synergistic, cross-domain effects on health, and may help identify factors that could potentially be targeted to reduce disease risk and improve lifespan health.

Inflammatory Measures in Depressed Patients With and Without a History of Adverse Childhood Experiences

Background: Major depressive disorder (MDD) is a complex psychiatric condition with different subtypes and etiologies. Exposure to adverse childhood experiences (ACE) is an important risk factor for the development of MDD later in life. Evidence suggests that pro-inflammatory processes may convey this risk as both MDD and ACE have been related to increased levels of inflammation. In the present study, we aimed to disentangle the effects of MDD and ACE on inflammation levels. Methods: Markers of inflammation (plasma interleukin(IL)-6 and high sensitive C-reactive protein (hsCRP) concentrations, white blood cell (WBC) count and a composite inflammation score (CIS) combining all three) were assessed in 23 MDD patients with ACE, 23 MDD patients without ACE, 21 healthy participants with ACE, and 21 healthy participants without ACE (mean age: 35 ± 11 (SD) years). None of the patients and participants was taking psychotropic medication. ACE was assessed with the Early Trauma Inventory (ETI) and was defined as moderate to severe exposure to sexual or physical abuse. Results: Group differences in the different inflammatory measures were observed. MDD patients with ACE showed significantly higher IL-6 concentrations (p = 0.018), higher WBC counts (p = 0.003) and increased general inflammation levels as indicated by the CIS (p = 0.003) compared to healthy controls. In contrast, MDD patients without ACE displayed similar inflammation levels to the control group (p = 0.93). Conclusion: We observed elevated inflammation in MDD patients with a history of ACE, which could indicate a subtype of "inflammatory depression". Accordingly, MDD patients with ACE might potentially benefit from anti-inflammatory therapies.