Association of major depressive disorder with serum myeloperoxidase and other markers of inflammation: a twin study

The role of the inflammatory markers ferritin, transferrin and fibrinogen in the relationship between major depression and cardiovascular disorders - The German Health Interview and Examination Survey

OBJECTIVE

To determine levels of inflammation (ferritin, transferrin and fibrinogen) in major depression (MDD) and comorbid cardiovascular disease (CVD) in an adult population.

METHOD

In 4181 participants of the German Health Interview and Examination Survey MDD was assessed through the Composite International Diagnostic Interview (CIDI). Coronary heart disease, stroke, and hypertension were diagnosed by a computer-assisted physician interview. Analyses were performed using anova models stratified for gender.

RESULTS

Ferritin, transferrin and fibrinogen levels showed opposing patterns in individuals with either CVD or MDD alone. In comorbidity analyses, male participants with MDD plus comorbid CHD or hypertension had lower levels of ferritin and lower fibrinogen levels in hypertension compared to men without MDD, while in women, results were inconsistent.

CONCLUSION

Opposing patterns of inflammatory markers in CVD or MDD alone were reversed when both conditions were present. MDD reduced levels of ferritin, transferrin and fibrinogen in CVD in a gender-specific way.

Blood mononuclear cell gene expression signature of postpartum depression

In sorrow thou shalt bring forth children (Genesis 3:16) seems as relevant today, with one of seven mothers afflicted by a depressive episode, constituting the most common medical complication after delivery. Why mothers are variably affected by mood symptoms postpartum remains unclear, and the pathogenesis and early molecular indicators of this divergent outcome have not been described. We applied a case-control design comparing differential global gene expression profiles in blood mononuclear cells sampled shortly after delivery at the time of inception of postpartum depression (PD). Nine antidepressant naive mothers showing high depressive scores and developing a persisting major depressive episode with postpartum onset were compared with 10 mothers showing low depressive scores and no depressive symptoms on prospective follow-up. A distinctive gene expression signature was observed after delivery among mothers with an emergent PD, with a significant overabundance of transcripts showing a high-fold differential expression between groups, and correlating with depressive symptom severity among all mothers. Early expression signatures correctly classified the majority of PD patients and controls. Those developing persisting PD exhibit a relative downregulation of transcription after delivery, with differential immune activation, and decreased transcriptional engagement in cell proliferation, and DNA replication and repair processes. Our data provide initial evidence indicating that blood cells sampled shortly after delivery may harbor valuable prognostic information for identifying the onset of persisting PD. Some of the informative transcripts and pathways may be implicated in the differential vulnerability that underlies depression pathogenesis.

Imaging phenotypes of major depressive disorder: genetic correlates

Imaging techniques are a potentially powerful method of identifying phenotypes that are associated with, or are indicative of, a vulnerability to developing major depressive disorder (MDD). Here we identify seven promising MDD-associated traits identified by magnetic resonance imaging (MRI) or positron emission tomography (PET). We evaluate whether these traits are state-independent, heritable endophenotypes, or state-dependent phenotypes that may be useful markers of treatment efficacy. In MDD, increased activity of the amygdala in response to negative stimuli appears to be a mood-congruent phenomenon, and is likely moderated by the 5-HT transporter gene (SLC6A4) promoter polymorphism (5-HTTLPR). Hippocampal volume loss is characteristic of elderly or chronically-ill samples and may be impacted by the val66met brain-derived neurotrophic factor (BDNF) gene variant and the 5-HTTLPR SLC6A4 polymorphism. White matter pathology is salient in elderly MDD cohorts but is associated with cerebrovascular disease, and is unlikely to be a useful marker of a latent MDD diathesis. Increased blood flow or metabolism of the subgenual anterior cingulate cortex (sgACC), together with gray matter volume loss in this region, is a well-replicated finding in MDD. An attenuation of the usual pattern of fronto-limbic connectivity, particularly a decreased temporal correlation in amygdala-anterior cingulate cortex (ACC) activity, is another MDD-associated trait. Concerning neuroreceptor PET imaging, decreased 5-HT(1A) binding potential in the raphe, medial temporal lobe, and medial prefrontal cortex (mPFC) has been strongly associated with MDD, and may be impacted by a functional single nucleotide polymorphism in the promoter region of the 5-HT(1A) gene (HTR1A: -1019 C/G; rs6295). Potentially indicative of inter-study variation in MDD etiology or mood state, both increased and decreased binding potential of the 5-HT transporter has been reported. Challenges facing the field include the problem of phenotypic and etiological heterogeneity, technological limitations, the confounding effects of medication, and non-disease related inter-individual variation in brain morphology and function. Further advances are likely as epigenetic, copy-number variant, gene-gene interaction, and genome-wide association (GWA) approaches are brought to bear on imaging data.

Major depression and coronary flow reserve detected by positron emission tomography

BACKGROUND

Major depressive disorder (MDD) is associated with coronary heart disease (CHD), but the mechanisms are unclear. The presence of MDD may increase CHD risk by affecting microvascular circulation. It is also plausible that genetic factors influencing MDD may overlap with those for CHD. We sought to examine the relationship between MDD and coronary flow reserve (CFR), the ratio of maximum flow during stress to flow at rest measured in milliliters per minute per gram of tissue.

METHODS

We examined 289 male middle-aged twins, including 106 twins (53 twin pairs) discordant for a lifetime history of MDD and 183 control twins (unrelated to any twins in the experimental group) without MDD. To calculate CFR, we used positron emission tomography with nitrogen 13 ((13)N) ammonia to evaluate myocardial blood flow at rest and after adenosine stress. A standard perfusion defect score was also used to assess myocardial ischemia.

RESULTS

There was no difference in myocardial ischemia between twins with and without MDD. Among the dizygotic twin pairs discordant for MDD, the CFR was 14% lower in the twins with MDD than in their brothers without MDD (2.36 vs 2.74) (P = .03). This association was not present in the monozygotic discordant pairs who were genetically matched (2.86 vs 2.64) (P = .19). The zygosity-MDD interaction after adjustment was significant (P = .006). The CFR in the dizygotic twins with MDD was also lower than in the control twins.

CONCLUSIONS

Our results provide evidence for a shared genetic pathway between MDD and microvascular dysfunction. Common pathophysiologic processes may link MDD and early atherosclerosis.

Similar immune profile in bipolar disorder and schizophrenia: selective increase in soluble tumor necrosis factor receptor I and von Willebrand factor

BACKGROUND

Alterations in the inflammatory system have been associated with schizophrenia and major depression, while bipolar disorder has been less studied. Most previous studies examined small samples, and the literature is inconsistent with regard to specific underlying immune mechanisms. In the present study, we examined markers representing different inflammatory pathways, and the aim was to investigate whether the levels of inflammatory parameters in a representative sample of bipolar disorder and schizophrenia are elevated compared to healthy controls, and to investigate whether the inflammatory profile is different between the groups.

METHODS

Plasma levels of soluble tumor necrosis factor receptor 1 (sTNF-R1), interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), high-sensitivity CRP (hs-CRP), soluble CD40L ligand (sCD40L), and von Willebrand factor (vWf) were measured with ELISA techniques in a catchment area based sample of consecutively referred patients with severe mental disorders [N = 311, comprising bipolar disorder (n = 125) and schizophrenia (n = 186)] and in healthy volunteers (n = 244).

RESULTS

Plasma levels of sTNF-R1 and vWf were statistically significantly increased in both bipolar disorder and schizophrenia compared to controls (p < 0.00001), and were also increased in unmedicated patients, but there were no major differences between the two diagnostic groups. Controlling for age, gender, ethnicity, cardiovascular disorders, kidney and liver function, and other confounders did not affect the results. There were no differences in other inflammation factors between the groups.

CONCLUSION

The present results indicate specific alterations of endothelium-related inflammation processes in both bipolar disorder and schizophrenia.

The impact of vascular burden on late-life depression

Small vessel pathology and microvascular lesions are no longer considered as minor players in the fields of cognitive impairment and mood regulation. Although frequently found in cognitively intact elders, both neuroimaging and neuropathological data revealed the negative impact on cognitive performances of their presence within neocortical association areas, thalamus and basal ganglia. Unlike cognition, the relationship between these lesions and mood dysregulation is still a matter of intense debate. Early studies focusing on the role of macroinfarct location in the occurrence of post-stroke depression (PSD) led to conflicting data. Later on, the concept of vascular depression proposed a deleterious effect of subcortical lacunes and deep white matter demyelination on mood regulation in elders who experienced the first depressive episode. More recently, the chronic accumulation of lacunes in thalamus, basal ganglia and deep white matter has been considered as a strong correlate of PSD. We provide here a critical overview of neuroimaging and neuropathological sets of evidence regarding the affective repercussions of vascular burden in the aging brain and discuss their conceptual and methodological limitations. Based on these observations, we propose that the accumulation of small vascular and microvascular lesions constitutes a common neuropathological platform for both cognitive decline and depressive episodes in old age.

Leisure time physical activity, risk of depressive symptoms, and inflammatory mediators: the English Longitudinal Study of Ageing

OBJECTIVES

To examine if inflammatory markers (CRP, fibrinogen) might partly explain the association between physical activity (PA) and risk of depression.

DESIGN/SETTING

The English Longitudinal Study of Ageing, a prospective study of community dwelling older adults.

PARTICIPANTS

4323 men and women (aged 63.4+/-9.7 yrs) free from depression at baseline.

MEASURES

Self reported leisure time PA levels and depressive symptoms (a score of > or = 4 using the 8-item CES-D scale) were assessed at baseline and 4 yrs follow up. The inflammatory markers, CRP and fibrinogen, were assessed at a 2 yrs intermediate time point between baseline and follow up.

RESULTS

At follow up 8% of the sample reported depressive symptomatology. In comparison with participants reporting none or light PA, the odds of depressive symptomatology for those reporting moderate or vigorous PA were 0.71 (95% CI, 0.54-0.95) and 0.58 (0.41-0.81), respectively, after adjustments for baseline CES-D score, age, gender, social-occupational class, smoking, alcohol, and chronic illness. Each standard unit increase in log CRP was associated with higher odds of depressive symptomatology at follow up (1.32, 1.13-1.55) and CRP was inversely associated with physical activity. The association between PA and depressive symptomatology was not, however, substantially modified by further adjustment for CRP (odds for none vs. vigorous PA=0.60, 0.43-0.84).

CONCLUSIONS

These data suggest that low grade systemic inflammation, as indexed by CRP, is a risk marker for depressive symptomatology, although this mechanism explains only a modest (approximately 5%) amount of the association between PA and risk of depression.

Persistent depressive symptomatology and inflammation: to what extent do health behaviours and weight control mediate this relationship?

We examined if persistent depressive symptoms are associated with markers of inflammation (C-Reactive Protein-CRP) and coagulation (fibrinogen), and if this association can be partly explained by weight control and behavioural risk factors (smoking, alcohol, physical activity). The study sample included 3609 men and women (aged 60.5+/-9.2 years) from The English Longitudinal Study of Ageing, a prospective study of community dwelling older adults. Depressive symptoms (using the 8-item CES-D scale), health behaviours (smoking, alcohol, physical activity), body weight, and central adiposity were assessed at baseline and 2 years follow up. CRP and fibrinogen were assessed at follow up. At baseline 12.7% of the sample reported elevated depressive symptomatology, which persisted in 6.1% of participants at follow up. Baseline CES-D score was associated with CRP (beta=.035, SE=.0066) and fibrinogen (beta=.023, SE=.0060) measured 2 years later. Using simple mediation analysis we observed both a direct association of depressive symptoms on CRP (beta=.013, SE=.0066) and indirect mediating effects through behavioural risk factors (beta for total indirect effect beta=.022, SE=.0023). For fibrinogen there were no direct effects of depression, and the association was entirely explained through indirect mediating effects of health behaviours. The presence of recurrent elevated depressive symptomatology at both time points was more strongly associated with CRP and fibrinogen. In summary, the association between depressive symptoms and low grade inflammation can be partly explained by behavioural risk factors. The presence of persistent depression appears to be associated with the greatest risk of elevated inflammation.

Acid hydrolysis followed by matrix-assisted laser desorption/ionization mass spectrometry for the rapid diagnosis of serum protein biomarkers in patients with major depression

We have developed a technique combining acid hydrolysis with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the rapid study of the changes in the levels of positive and negative acute phase protein biomarkers in the sera of patients suffering from major depression. The serum proteins were first precipitated using an organic solvent; after separation, they were subjected to hydrochloric acid hydrolysis (6 M HCl) for 10 min. The resulting peptides were characterized using MALDI-TOF MS. Short-term treatment of the serum proteins with HCl efficiently removed interference from the abundant protein - albumin - and produced abundant peptide ion signals in the range of m/z 4000-10 000. This approach allowed us to rapidly detect the peptide ions originating from transferrin (a common negative acute phase protein) and fibrinogen (a common positive acute phase protein). The average ratios and (standard deviations) of the ion signals derived from transferrin/fibrinogen were 3.58 (+/-1.93) for the healthy control subjects and 1.02 (+/-0.52) for the patients suffering from major depression. The differences in transferrin/fibrinogen ratios between healthy controls and patients suggest that major depression will induce internal inflammation and cause either an increase in the level of fibrinogen or a decrease in the level of transferrin.

Does hypothalamic-pituitary-adrenal axis hypofunction in chronic fatigue syndrome reflect a 'crash' in the stress system?

The etiopathogenesis of chronic fatigue syndrome (CFS) remains poorly understood. Although neuroendocrine disturbances - and hypothalamic-pituitary-adrenal (HPA) axis hypofunction in particular - have been found in a large proportion of CFS patients, it is not clear whether these disturbances are cause or consequence of the illness. After a review of the available evidence we hypothesize that that HPA axis hypofunction in CFS, conceptualized within a system-biological perspective, primarily reflects a fundamental and persistent dysregulation of the neurobiological stress system. As a result, a disturbed balance between glucocorticoid and inflammatory signaling pathways may give rise to a pathological cytokine-induced sickness response that may be the final common pathway underlying central CFS symptoms, i.e. effort/stress intolerance and pain hypersensitivity. This comprehensive hypothesis on HPA axis hypofunction in CFS may stimulate diagnostic refinement of the illness, inform treatment approaches and suggest directions for future research, particularly focusing on the neuroendocrine-immune interface and possible links between CFS, early and recent life stress, and depression.

Decreased heart rate variability in patients with cirrhosis relates to the presence and degree of hepatic encephalopathy

Heart rate variability (HRV) is reduced in several clinical settings associated with either systemic inflammation or neuropsychiatric impairment. The possibility that the changes in HRV observed in patients with neuropsychiatric impairment might relate to the overproduction of inflammatory cytokines does not seem to have been considered in the studies undertaken to date. HRV is decreased in patients with liver cirrhosis but its relationship to the impairment of neuropsychiatric performance, commonly observed in these patients, is unknown. The aim of this study was to investigate the relationship between HRV, hepatic encephalopathy, and production of inflammatory cytokines in patients with cirrhosis. Eighty patients with cirrhosis [53 men, 27 women; mean (+/-1SD) age 54 +/- 10 yr], classified as neuropsychiatrically unimpaired or as having minimal or overt hepatic encephalopathy, and 11 healthy subjects were studied. HRV was assessed by applying Poincaré plot analysis to the R-R interval series on a 5-min ECG. Inflammatory cytokines (TNF-alpha, IL-6, IL-10, and IL-12) were measured in a subgroup of patients. Long-term R-R variability was significantly decreased in the patients with cirrhosis, in parallel with the degree of neuropsychiatric impairment (P < 0.01) and independently of the degree of hepatic dysfunction (P = 0.011). The relative risk of death increased by 7.7% for every 1-ms drop in this variable. Plasma levels of IL-6 significantly correlated with indexes of both HRV and neuropsychiatric performance. The changes observed in HRV and in neuropsychiatric status in patients with cirrhosis are significantly correlated, most likely reflecting a common pathogenic mechanism mediated by inflammatory cytokines.

Common genetic contributions to depressive symptoms and inflammatory markers in middle-aged men: the Twins Heart Study

OBJECTIVE

To examine the extent to which a common genetic pathway is also involved in the relationship between depressive symptoms, in the absence of major depressive disorder (MDD), and inflammation. Recent data suggested that MDD and inflammation share common genes.

METHODS

We recruited 188 male twins from the Vietnam Era Twin Registry who were free of symptomatic coronary artery disease and MDD, with mean +/- standard deviation (SD) age of 55 +/- 2.75 years, including 54 monozygotic and 40 dizygotic twin pairs. These pairs were assessed for two inflammatory markers, interleukin (IL)-6 and C-reactive protein (CRP). Current depressive symptoms were measured with the Beck Depression Inventory-II. Generalized estimating equations were used to examine the phenotypic association between depression and inflammatory markers. Biometrical genetic modeling was performed to estimate the genetic and environmental contributions to this association.

RESULTS

An association was observed between severity of current depressive symptoms and increased levels of inflammatory markers (p < .001 for IL-6 and p = .005 for CRP). After adjustment for other factors, the association was slightly attenuated but remained statistically significant for IL-6 (p = .002). The heritability of IL-6, CRP, and depressive symptoms were estimated as 0.37, 0.65, and 0.48, respectively. Genetic modeling found a significant genetic correlation between IL-6 and depressive symptoms (r(G) = 0.22, p = .046), indicating that about 66% of the covariance between them can be explained by shared genetic influences.

CONCLUSIONS

Current depressive symptoms are significantly correlated with inflammatory markers. This covariation is due, in large part, to genes that are common to depressive symptoms and inflammation.