Fight the Fire: Association of Cytokine Genomic Markers and Suicidal Behavior May Pave the Way for Future Therapies

The fight against suicide is highly challenging as it may be one of the most complex and, at the same time, most threatening among all psychiatric phenomena. In spite of its huge impact, and despite advances in neurobiology research, understanding and predicting suicide remains a major challenge for both researchers and clinicians. To be able to identify those patients who are likely to engage in suicidal behaviors and identify suicide risk in a reliable and timely manner, we need more specific, novel biological and genetic markers/indicators to develop better screening and diagnostic methods, and in the next step to utilize these molecules as intervention targets. One such potential novel approach is offered by our increasing understanding of the involvement of neuroinflammation based on multiple observations of increased proinflammatory states underlying various psychiatric disorders, including suicidal behavior. The present paper overviews our existing understanding of the association between suicide and inflammation, including peripheral and central biomarkers, genetic and genomic markers, and our current knowledge of intervention in suicide risk using treatments influencing inflammation; also overviewing the next steps to be taken and obstacles to be overcome before we can utilize cytokines in the treatment of suicidal behavior.

C-Reactive Protein (CRP): A Potent Inflammation Biomarker in Psychiatric Disorders

An increasing number of studies have investigated the role of inflammation in psychiatric disorders, by demonstrating how an altered/dysfunctional immunological and inflammatory system may underpin a psychiatric condition. Particularly, several studies specifically investigated the role of a neuroinflammatory biomarker, named C-reactive protein (CRP), in psychiatric disorders. Overall, even though scientific literature so far published still does not appear definitive, CRP is more likely reported to be elevated in several psychiatric disorders, including schizophrenia, mood disorders, anxiety disorders and post-traumatic stress disorder. Moreover, a low-grade inflammation (CRP >3 mg/L) has been more likely observed in a subgroup of patients affected with a more severe psychopathological symptomatology, more treatment resistance and worst clinical mental illness course, strengthening the hypothesis of the need for a different clinical and prognostic characterization based on this concomitant neuroinflammatory predisposition. However, even though further research studies are needed to confirm this preliminary evidence, CRP may represent a potential clinical routine biomarker which could be integrated in the clinical routine practice to better characterize clinical picture and course as well as address clinicians towards a personalized treatment.

C-Reactive Protein Gene Variants in Depressive Symptoms & Antidepressants Efficacy

OBJECTIVE

Although the pathogenesis of depression remains unclear, C-reactive protein (CRP) levels are commonly elevated in depressed patients. Thus, CRP single-nucleotide polymorphisms (SNPs) that influence CRP levels may be associated with depression. In the present study, we explored whether CRP SNPs are related to depressive symptoms and antidepressants efficacy in Han Chinese patients.

METHODS

We analyzed data from 440 patients with first-episode depression. We obtained genome CRP SNPs, scores of the 17-item Hamilton Rating Scale for Depression 17 (HAMD17) and its four-factor at baseline and after 6 weeks. Quantitative trait analysis was performed using UNPHASED software and curative effects were analyzed using SPSS software.

RESULTS

Male patients with SNP rs1800947G exhibited lower insomnia scores and rs2794521CC exhibited lower scores of anxiety/ physical symptoms, total HAMD17 score. Female patients with rs2794521TT exhibited higher scores of insomnia and lower antidepressants efficacy.

CONCLUSION

CRP SNPs rs1800947 and rs2794521 may be associated with depressive symptoms in patients with depression in a sexspecific fashion. Furthermore, rs2794521 may be a predictor of the efficacy of antidepressants in female patients.

Associations between autistic-like traits and polymorphisms in NFKBIL1

OBJECTIVE

The immune system has been suggested to be associated with neuropsychiatric disorders; for example, elevated levels of cytokines and the inflammation-related transcription factor nuclear factor kappa-B (NF-κB) have been reported in individuals with autism spectrum disorder (ASD). The aim of this study was to investigate possible associations between autistic-like traits (ALTs) and single nucleotide polymorphisms (SNPs) in NFKB1 (encoding a subunit of the NF-κB protein complex) and NF-κB inhibitor-like protein 1 (NFKBIL1).

METHODS

The study was conducted in a cohort from the general population: The Child and Adolescent Twin Study in Sweden (CATSS, n = 12 319, 9-12 years old). The subjects were assessed by the Autism-Tics, ADHD, and Other Comorbidities Inventory. Five SNPs within the two genes were genotyped (NFKBIL1: rs2857605, rs2239707, rs2230365 and rs2071592; NFKB1: rs4648022).

RESULTS

We found significant associations for two SNPs in NFKBIL1: rs2239707 showed a significant distribution of genotype frequencies in the case-control analysis both for all individuals combined and in boys only, and rs2230365 was significantly associated with the ALTs-module language impairment in boys only. Furthermore, we found nominal association in the case-control study for rs2230365, replicating earlier association between this SNP and ASD in an independent genome-wide association study.

CONCLUSION

The shown associations between polymorphisms in NFKBIL1 and ALTs are supporting an influence of the immune system on neuropsychiatric symptoms.

Predictive value of sICAM-1 and sVCAM-1 as biomarkers of affective temperaments in healthy young adults

BACKGROUND

Affective temperaments are intermediate phenotypes for major affective disorders and are reported to have a neuroimmune etiopathogenesis. Here we investigated the role of soluble intercellular cell adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) in affective temperaments and mood symptoms in healthy adults.

METHODS

Healthy adults (n=94) were screened for psychiatric disorders using the nonpatient version of the Structured Clinical Interview for DSM-IV-I and II. Subjects with medical conditions associated with changes in inflammatory response were excluded, deriving the final sample (n=68). Affective temperaments were evaluated with Temperament Evaluation of Memphis, Pisa, Paris and San Diego-Autoquestionnaire (TEMPS-A). State mood symptoms were assessed using the Young Mania Rating Scale and Montgomery-Åsberg Depression Rating Scale. Serum sICAM-1 and sVCAM-1 levels were measured using enzyme-linked immunosorbent assay.

RESULTS

After adjusting for confounders (age, gender, BMI, and smoking habits), a high negative correlation between depressive and irritable temperament TEMPS-A scores and sVCAM-1 levels was detected. Although we identified no association between sICAM-1 levels and affective temperament scores, sICAM-1 was related to the state severity of manic symptoms. In a multiple linear regression model, sVCAM-1 remained a significant predictor of depressive but not irritable temperament scores.

LIMITATIONS

The temperaments were estimated on the basis of self-report questionnaire.

CONCLUSIONS

Our findings suggest that sVCAM-1 is related to affective temperaments, and it is a trait marker for liability to mood disorders. This relationship between alterations in cellular adhesion and affective temperament may be important for vulnerability to affective disorders.

Neuroinflammation in suicide: Toward a comprehensive model

OBJECTIVES

Suicidal behaviour (SB) entered the DSM-5, underlying a specific biological vulnerability. Then, recent findings suggested a possible role of the immune system in SB pathogenesis. The objective of this review is to present these main immune factors involved in SB pathogenesis.

METHODS

We conducted a review using Preferred Reporting Items for Systematic reviews and Meta-Analysis criteria, and combined ("Inflammation") AND ("Suicidal ideation" OR "Suicidal attempt" OR "suicide").

RESULTS

Post mortem studies demonstrated associations between suicide and inflammatory cytokines in the orbitofrontal cortex, a brain region involved in suicidal vulnerability. Also, microgliosis and monocyte-macrophage system activation may be a useful marker of suicide neurobiology. Kynurenine may influence inflammatory processes, and related molecular pathways may be involved in SB pathophysiology. Few recent studies associated inflammatory markers with suicidal vulnerability: serotonin dysfunction, impulsivity and childhood trauma. Interestingly, the perception of threat that leads suicidal individuals to contemplate suicide may activate biological stress responses, including inflammatory responses.

CONCLUSIONS

Translational projects would be crucial to identify a specific marker in SB disorders, to investigate its clinical correlations, and the interaction between inflammatory cytokines and monoamine systems in SB. These researches might lead to new biomarkers and novel directions for therapeutic strategies.

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.

Is the Gly82Ser polymorphism in the RAGE gene relevant to schizophrenia and the personality trait psychoticism?

BACKGROUND

The receptor for advanced glycation end products (RAGE) is the main receptor for S100B, an astrogial proinflammatory mediator that has been suggested to be involved in the pathophysiology of schizophrenia. To further elucidate the possible relevance of inflammation for mental functions, we investigated a functional polymorphism in the gene coding for RAGE in relation to personality traits and susceptibility to schizophrenia.

METHODS

We studied the Gly82Ser polymorphism (rs2070600, 244G>A) in 2 population-based cohorts of middle-aged participants assessed using the Karolinska Scales of Personality. In addition, we compared genotype frequencies between patients with schizophrenia and controls.

RESULTS

The population-based cohorts included 270 women and 247 men, and the case-control study involved 138 patients with schizophrenia and 258 controls. In the population-based cohorts, 82Ser carriers were found to have significantly higher scores for the psychoticism personality trait comprising the detachment and suspicion subscales. The case-control study revealed that the 82Ser allele was significantly more frequent among patients than controls.

LIMITATIONS

This study was limited by the modest sample size and the use of a self-report measure to assess personality traits.

CONCLUSION

Our findings suggest that the proven relation between certain personality traits and schizophrenia can at least to some extent be explained on a genetic level. Also, the activated S100B-RAGE axis may be an underlying cause, not only a consequence, of the disease.

Genetic variability within the S100B gene influences the personality trait self-directedness

Elevated serum levels of S100B have proven useful as an indicator of brain-injury but have also been shown in patients diagnosed with psychiatric disorders. Recently, associations were found between variations in the S100B gene and schizophrenia as well as bipolar affective disorder. The aim of the present study was to investigate whether some of these genetic variations influence general aspects of human behaviour as portrayed by normal dimensions of personality. Two single nucleotide polymorphisms within the S100B gene, 2757C>G and 5748C>T, were genotyped in two population based cohorts consisting of 42-year-old women (n=270) and 51-year-old men (n=247), respectively. The two polymorphisms were analysed with respect to personality traits assessed using the Temperament and Character Inventory (TCI). In men, the 2757C>G polymorphism was found to significantly influence the TCI dimension self-directedness with higher scores in 2757G homozygotes. A similar tendency towards association was seen in the female cohort; however, this correlation did not remain significant after correction for multiple comparisons. Furthermore, the 5748C>T polymorphism was highly associated with self-directedness in men. Self-directedness is an overall estimate of adaptive strategies to adjust behaviour to conceptual goals as well as coping strategies and is strongly correlated to general mental health and absence of personality disorder. These preliminary findings suggest that the S100B gene may be implicated not only in certain pathological brain conditions but also in processes involved in normal behaviour.

Association of existing and new candidate genes for anxiety, depression and personality traits in older people

Genetic variants that have previously been associated with personality traits and/or psychological distress, or inflammatory marker levels were investigated for their relationship to self-rated personality traits, anxiety, and depression in two elderly Scottish cohorts. Ten genes (29 SNPs) were investigated in the Lothian Birth Cohort 1936 (approximately 70 years, N = 1,091). Four of these genes and seven others (35 SNPs) were tested in the Lothian Birth Cohort 1921 who were measured on the same traits and states on two occasions (approximately 80 years, N = 550; 87 years, N = 229). For previously investigated candidate genes, some support (at a nominal significance level of 0.05/0.01) was found for association between NOS1 and personality traits (especially extraversion), PSEN1 and depression/neuroticism, and GRIK3 and depression. Of the inflammatory marker candidate genes, TF showed some association with psychological distress. No SNPs withstood the correction to significance level for multiple testing. Nevertheless, the results will be of importance to future meta-analyses of these candidate genes in relation to psychological distress and personality.

Resilience and mental health

The relationship between disease and good health has received relatively little attention in mental health. Resilience can be viewed as a defence mechanism, which enables people to thrive in the face of adversity and improving resilience may be an important target for treatment and prophylaxis. Though resilience is a widely-used concept, studies vary substantially in their definition, and measurement. Above all, there is no common underlying theoretical construct to this very heterogeneous research which makes the evaluation and comparison of findings extremely difficult. Furthermore, the varying multi-disciplinary approaches preclude meta-analysis, so that clarification of research in this area must proceed firstly by conceptual unification. We attempt to collate and classify the available research around a multi-level biopsychosocial model, theoretically and semiotically comparable to that used in describing the complex chain of events related to host resistance in infectious disease. Using this underlying construct we attempt to reorganize current knowledge around a unitary concept in order to clarify and indicate potential intervention points for increasing resilience and positive mental health.

Serum adenosine deaminase activity in gestational diabetes mellitus and normal pregnancy

PURPOSE

To our knowledge, there is no report regarding adenosine deaminase activity (ADA) in gestational diabetes mellitus (GDM). The aim of the present study was to investigate the level of serum ADA activity in normal pregnancy, GDM and normal non-pregnant women.

METHODS

The serum catalytic concentration of ADA was measured in samples of 20 GDM, 40 normal pregnant and 20 non-pregnant healthy women.

RESULTS

Adenosine deaminase activity was significantly higher in GDM (24.30 +/- 8.04 IU/L) and pregnant women (23.88 +/- 8.66 IU/L) than those of normal non-pregnant individuals (11.85 +/- 3.23 IU/L) (P < 0.0001), but the ADA level was not significantly different from GDM and normal pregnant women (P = 0.97).

CONCLUSIONS

Adenosine deaminase activity was significantly higher in GDM and pregnant individuals than normal group in this study. Previous reports in this field are contentious; therefore, ADA activity could be regulated in different population by immunologic and genetic factors.