VEGF-related polymorphisms identified by GWAS and risk for major depression

Transcriptomic decoding of regional cortical vulnerability to major depressive disorder

Previous studies in small samples have identified inconsistent cortical abnormalities in major depressive disorder (MDD). Despite genetic influences on MDD and the brain, it is unclear how genetic risk for MDD is translated into spatially patterned cortical vulnerability. Here, we initially examined voxel-wise differences in cortical function and structure using the largest multi-modal MRI data from 1660 MDD patients and 1341 controls. Combined with the Allen Human Brain Atlas, we then adopted transcription-neuroimaging spatial correlation and the newly developed ensemble-based gene category enrichment analysis to identify gene categories with expression related to cortical changes in MDD. Results showed that patients had relatively circumscribed impairments in local functional properties and broadly distributed disruptions in global functional connectivity, consistently characterized by hyper-function in associative areas and hypo-function in primary regions. Moreover, the local functional alterations were correlated with genes enriched for biological functions related to MDD in general (e.g., endoplasmic reticulum stress, mitogen-activated protein kinase, histone acetylation, and DNA methylation); and the global functional connectivity changes were associated with not only MDD-general, but also brain-relevant genes (e.g., neuron, synapse, axon, glial cell, and neurotransmitters). Our findings may provide important insights into the transcriptomic signatures of regional cortical vulnerability to MDD.

A further examination of growth factors, T helper 1 polarization, and the gut microbiome in major depression: Associations with reoccurrence of illness, cognitive functions, suicidal behaviors, and quality of life

Growth factors, T helper (Th)1 polarization, and the microbiome are involved in the pathophysiology of major depression (MDD). It remains unclear whether the combination of these three pathways could enhance the accuracy of predicting the features of MDD, including recurrence of illness (ROI), suicidal behaviors and the phenome. We measured serum stem cell factor (SCF), stem cell growth factor (SCGF), stromal cell-derived factor-1 (SDF-1), platelet-derived growth factor (PDGF), hepatocyte growth factor (HGF), macrophage-colony stimulating factor (M-CSF) and vascular endothelial growth factor (VEGF), the ratio of serum Th1/Th2 cytokines (zTh1-zTh2), and the abundances of gut microbiome taxa by analyzing stool samples using 16S rDNA sequencing from 32 MDD patients and 37 healthy controls. The results show that serum SCF is significantly lower and VEGF increased in MDD. Adverse childhood experiences (ACE) and ROI are significantly associated with lowered SCF and increasing VEGF. Lifetime and current suicidal behaviors are strongly predicted (63.5%) by an increased VEGF/SCF ratio, Th1 polarization, a gut microbiome enterotype indicating gut dysbiosis, and lowered abundance of Dorea and Faecalobacterium. Around 80.5% of the variance in the phenome's severity is explained by ROI, ACEs, and lowered Parabacteroides distasonis and Clostridium IV abundances. A large part of the variance in health-related quality of life (54.1%) is explained by the VEGF/SCF ratio, Th1 polarization, ACE, and male sex. In conclusion, key features of MDD are largely predicted by the cumulative effects of ACE, Th1 polarization, aberrations in growth factors and the gut microbiome with increased pathobionts but lowered beneficial symbionts.

Vagus Nerve Stimulation Modulates Inflammation in Treatment-Resistant Depression Patients: A Pilot Study

Vagal neurostimulation (VNS) is used for the treatment of epilepsy and major medical-refractory depression. VNS has neuropsychiatric functions and systemic anti-inflammatory activity. The objective of this study is to measure the clinical efficacy and impact of VNS modulation in depressive patients. Six patients with refractory depression were enrolled. Depression symptoms were assessed with the Montgomery-Asberg Depression Rating, and anxiety symptoms with the Hamilton Anxiety Rating Scale. Plasmas were harvested prospectively before the implantation of VNS (baseline) and up to 4 years or more after continuous therapy. Forty soluble molecules were measured in the plasma by multiplex assays. Following VNS, the reduction in the mean depression severity score was 59.9% and the response rate was 87%. Anxiety levels were also greatly reduced. IL-7, CXCL8, CCL2, CCL13, CCL17, CCL22, Flt-1 and VEGFc levels were significantly lowered, whereas bFGF levels were increased (p values ranging from 0.004 to 0.02). This exploratory study is the first to focus on the long-term efficacy of VNS and its consequences on inflammatory biomarkers. VNS may modulate inflammation via an increase in blood-brain barrier integrity and a reduction in inflammatory cell recruitment. This opens the door to new pathways involved in the treatment of refractory depression.

The Association of Biochemical and Genetic Biomarkers in VEGF Pathway with Depression

VEGF is an important neurotrophic and vascular factor involved in mental disorders. The objective of this study was to verify the effect of genetic polymorphisms in the VEGF pathway on the risk for depression, symptom intensity, and suicide attempts. To examine the association between the VEGF pathway and depression, we genotyped polymorphisms and measured the plasma concentrations of VEGF, KDR, and FLT1 proteins. The participants were 160 patients with depression and 114 healthy controls. The questionnaires that assessed the clinical profile of the patients were the MINI-International Neuropsychiatric Interview, GRID-HAMD₂₁, CTQ, BSI, and the number of suicide attempts. Genotyping of participants was performed using the real-time PCR and protein measurements were performed using the enzyme-linked immunosorbent assay (ELISA). VEGF and its inhibitors were reduced in depression. Individuals with depression and displaying the homozygous AA of the rs699947 polymorphism had higher plasma concentrations of VEGF (p-value = 0.006) and were associated with a greater number of suicide attempts (p-value = 0.041). Individuals with depression that were homozygous for the G allele of the FLT1 polymorphism rs7993418 were associated with lower symptom severity (p-value = 0.040). Our results suggest that VEGF pathway polymorphisms are associated with the number of suicide attempts and the severity of depressive symptoms.

Forgetful, sad and old: Do vascular cognitive impairment and depression share a common pre-disease network and how is it impacted by ageing?

Vascular cognitive impairment (VCI) and depression frequently coexist in geriatric populations and reciprocally increase disease risks. We assert that a shared pre-disease state of the psycho-immune-neuroendocrine (PINE) network model mechanistically explains bidirectional associations between VCI and depression. Five pathophysiological sub-networks are identified that are shared by VCI and depression: neuroinflammation, kynurenine pathway imbalance, hypothalamic-pituitary-adrenal (HPA) axis overactivity, impaired neurotrophic support and cerebrovascular dysfunction. These do not act independently, and their complex interactions necessitate a systems biology approach to better define disease pathogenesis. The PINE network is already established in the context of non-communicable diseases (NCDs) such as depression, hypertension, atherosclerosis, coronary heart disease and type 2 diabetes mellitus. We build on previous literature to specifically explore mechanistic links between MDD and VCI in the context of PINE pathways and discuss key mechanistic commonalities linking these comorbid conditions and identify a common pre-disease state which precedes transition to VCI and MDD. We expand the model to incorporate bidirectional interactions with biological ageing. Diathesis factors for both VCI and depression feed into this network and the culmination of shared mechanisms (on an ageing substrate) lead to a critical network transition to one or both disease states. A common pre-disease state underlying VCI and depression can provide clinicians a unique opportunity for early risk assessment and intervention in disease development. Establishing the mechanistic elements and systems biology of this network can reveal early warning or predictive biomarkers together with novel therapeutic targets. Integrative studies are recommended to elucidate the dynamic networked biology of VCI and depression over time.

Growth factors in anorexia nervosa: a systematic review and meta-analysis of cross-sectional and longitudinal data

OBJECTIVES

Growth factors are signalling molecules that play roles in the survival, proliferation, migration, and differentiation of cells. Studies have found alterations in specific growth factors in anorexia nervosa (AN).

METHODS

This systematic review and meta-analysis examined articles from three databases, measuring growth factors in AN cross-sectionally and longitudinally, and in recovered AN (rec-AN) cross-sectionally. Random-effects meta-analyses were conducted for brain-derived neurotrophic factor (BDNF) and insulin growth factor-I (IGF-1) for cross-sectional and longitudinal studies.

RESULTS

A total of 82 studies were included: 56 cross-sectional (BDNF: n = 15; IGF-1: n = 41) and 24 longitudinal (BDNF: n = 5; IGF-1: n = 19) were meta-analysed and 20 studies were narratively synthesised. In cross-sectional analyses, BDNF and IGF-1 were lower in AN compared to controls, and BDNF was marginally greater in rec-AN compared to controls. In longitudinal meta-analyses, BDNF and IGF-1 increased from baseline to follow-up. Cross-sectional subgroup analyses revealed no differences in BDNF between controls and AN binge-eating/purging subtypes.

CONCLUSIONS

It is likely that the low BDNF and IGF-1 levels found in AN are consequences of starvation, which are reversible with weight restoration. The increase in BDNF and IGF-1 during therapeutic weight restoration might improve neuroplasticity, which is the basis of learning, and thus psychotherapeutic success.

VEGF-A-related genetic variants protect against Alzheimer's disease

The Apolipoprotein E (APOE) genotype has been shown to be the strongest genetic risk factor for Alzheimer’s disease (AD). Moreover, both the lipolysis-stimulated lipoprotein receptor (LSR) and the vascular endothelial growth factor A (VEGF-A) are involved in the development of AD. The aim of the study was to develop a prediction model for AD including single nucleotide polymorphisms (SNP) of APOE, LSR and VEGF-A-related variants.

The population consisted of 323 individuals (143 AD cases and 180 controls). Genotyping was performed for: the APOE common polymorphism (rs429358 and rs7412), two LSR variants (rs34259399 and rs916147) and 10 VEGF-A-related SNPs (rs6921438, rs7043199, rs6993770, rs2375981, rs34528081, rs4782371, rs2639990, rs10761741, rs114694170, rs1740073), previously identified as genetic determinants of VEGF-A levels in GWAS studies. The prediction model included direct and epistatic interaction effects, age and sex and was developed using the elastic net machine learning methodology.

An optimal model including the direct effect of the APOE e4 allele, age and eight epistatic interactions between APOE and LSR, APOE and VEGF-A-related variants was developed with an accuracy of 72%. Two epistatic interactions (rs7043199*rs6993770 and rs2375981*rs34528081) were the strongest protective factors against AD together with the absence of ε4 APOE allele. Based on pathway analysis, the involved variants and related genes are implicated in neurological diseases.

In conclusion, this study demonstrated links between APOE, LSR and VEGF-A-related variants and the development of AD and proposed a model of nine genetic variants which appears to strongly influence the risk for AD.

A Systematic Review of Candidate Genes for Major Depression

Background and Objectives: The aim of this systematic review was to analyse which candidate genes were examined in genetic association studies and their association with major depressive disorder (MDD). Materials and Methods: We searched PUBMED for relevant studies published between 1 July 2012 and 31 March 2019, using combinations of keywords: “major depressive disorder” OR “major depression” AND “gene candidate”, “major depressive disorder” OR “major depression” AND “polymorphism”. Synthesis focused on assessing the likelihood of bias and investigating factors that may explain differences between the results of studies. For selected gene list after literature overview, functional enrichment analysis and gene ontology term enrichment analysis were conducted. Results: 141 studies were included in the qualitative review of gene association studies focusing on MDD. 86 studies declared significant results (p < 0.05) for 172 SNPs in 85 genes. The 13 SNPs associations were confirmed by at least two studies. The 18 genetic polymorphism associations were confirmed in both the previous and this systematic analysis by at least one study. The majority of the studies (68.79 %) did not use or describe power analysis, which may have had an impact over the significance of their results. Almost a third of studies (N = 54) were conducted in Chinese Han population. Conclusion: Unfortunately, there is still insufficient data on the links between genes and depression. Despite the reported genetic associations, most studies were lacking in statistical power analysis, research samples were small, and most gene polymorphisms have been confirmed in only one study. Further genetic research with larger research samples is needed to discern whether the relationship is random or causal. Summations: This systematic review had summarized all reported genetic associations and has highlighted the genetic associations that have been replicated. Limitations: Unfortunately, most gene polymorphisms have been confirmed only once, so further studies are warranted for replicating these genetic associations. In addition, most studies included a small number of MDD cases that could be indicative for false positive. Considering that polymorphism loci and associations with MDD is also vastly dependent on interpersonal variation, extensive studies of gene interaction pathways could provide more answers to the complexity of MDD.

Pathomechanisms of Vascular Depression in Older Adults

Depression in older individuals is a common complex mood disorder with high comorbidity of both psychiatric and physical diseases, associated with high disability, cognitive decline, and increased mortality The factors predicting the risk of late-life depression (LLD) are incompletely understood. The reciprocal relationship of depressive disorder and age- and disease-related processes has generated pathogenic hypotheses and provided various treatment options. The heterogeneity of depression complicates research into the underlying pathogenic cascade, and factors involved in LLD considerably differ from those involved in early life depression. Evidence suggests that a variety of vascular mechanisms, in particular cerebral small vessel disease, generalized microvascular, and endothelial dysfunction, as well as metabolic risk factors, including diabetes, and inflammation that may induce subcortical white and gray matter lesions by compromising fronto-limbic and other important neuronal networks, may contribute to the development of LLD. The "vascular depression" hypothesis postulates that cerebrovascular disease or vascular risk factors can predispose, precipitate, and perpetuate geriatric depression syndromes, based on their comorbidity with cerebrovascular lesions and the frequent development of depression after stroke. Vascular burden is associated with cognitive deficits and a specific form of LLD, vascular depression, which is marked by decreased white matter integrity, executive dysfunction, functional disability, and poorer response to antidepressive therapy than major depressive disorder without vascular risk factors. Other pathogenic factors of LLD, such as neurodegeneration or neuroimmune regulatory dysmechanisms, are briefly discussed. Treatment planning should consider a modest response of LLD to antidepressants, while vascular and metabolic factors may provide promising targets for its successful prevention and treatment. However, their effectiveness needs further investigation, and intervention studies are needed to assess which interventions are appropriate and effective in clinical practice.

Vascular Endothelial Growth Factor as a Putative Biomarker of Depression in Asthmatics with Reversible Airway Narrowing

The vascular endothelial growth factor (VEGF) plays a pivotal role in process of angiogenesis in adults. If angiogenesis is not properly controlled, its deregulation may implicate it in various psychosomatic diseases states. The aim of our study was to reveal possible correlation between severity of depression in asthmatics with different degrees of airway narrowing and serum vascular endothelial growth factor levels. The study population included a total of 122 adult subjects: 82 patients with asthma (among them 42 patients with irreversible bronchoconstriction and 40 patients with reversible bronchoconstriction) and 40 healthy participants as a control group. The standardized Beck Depression Inventory (BDI) was used to estimate the depression symptoms. Enzyme-linked immunosorbent assay (ELISA) was used to assess the VEGF serum concentration in all participants. There was a significant difference in depression symptoms in asthmatics with reversible (p = 0.0432) and irreversible airway obstruction (p = 0.00005) in comparison to control group and between these two subgroups of asthmatics (p = 0.0233). Obtained results revealed significant correlation between level of depression and mean VEGF serum concentration in asthmatics with reversible airway obstruction (p = 0.0202). There was no difference between enhanced depression symptoms and VEGF serum concentration in patients with irreversible airway obstruction nor in the total group of asthmatics (in both p > 0.05). The relationship between asthma severity and depression symptoms seems to be certain. VEGF might be considered as a putative biomarker of depression in asthmatics, mainly those with reversible airway narrowing.

Involvement of vascular endothelial growth factor in schizophrenia

Vascular endothelial growth factor (VEGF), which acts as an angiogenic and neurotrophic factor, is involved the regulation of cerebral blood volume and flow in Schizophrenia (SCZ). Several evidence indicates that modification of brain blood circulation due to alterations in the VEGF system affects cognitive performance and brain function in patients with SCZ. The aim of this study is: 1) To analyze the literature data concerning the role of VEGF in modulating the angiogenic response in SCZ. These data are controversial because some studies found elevated VEGF serum levels of VEGF in patients with SCZ, whereas others demonstrated no significant differences between SCZ patients and controls. 2)To analyze the role of VEGF as a predictive factor on the effects of antipsychotics agents used in the treatment of SCZ. In this context, high VEGF levels, associated to better responses to antipsychotics, might be predictive of the use of first generation antipsycotic drugs, whereas low VEGF levels, expression of resistance to therapy, might be predictive for the use of second generation antipsycotic drugs.

Potential depression and antidepressant-response biomarkers in human lymphoblast cell lines from treatment-responsive and treatment-resistant subjects: roles of SSRIs and omega-3 polyunsaturated fatty acids

While several therapeutic strategies exist for depression, most antidepressant drugs require several weeks before reaching full biochemical efficacy and remission is not achieved in many patients. Therefore, biomarkers for depression and drug-response would help tailor treatment strategies. This study made use of banked human lymphoblast cell lines (LCLs) from normal and depressed subjects; the latter divided into remitters and non-remitters. Due to the fact that previous studies have shown effects on growth factors, cytokines, and elements of the cAMP-generating system as potential biomarkers for depression and antidepressant action, these were examined in LCLs. Initial gene and protein expression profiles for signaling cascades related to neuroendocrine and inflammatory functions differ among the three groups. Growth factor genes, including VEGFA and BDNF were significantly down-regulated in cells from depressed subjects. In addition, omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been reported to act as both antidepressants and anti-inflammatories, but the mechanisms for these effects are not established. Here we showed that n-3 PUFAs and escitalopram (selective serotonin reuptake inhibitors, SSRIs) treatment increased adenylyl cyclase (AC) and BDNF gene expression in LCLs. These data are consistent with clinical observations showing that n-3 PUFA and SSRI have antidepressant affects, which may be additive. Contrary to observations made in neuronal and glial cells, n-3 PUFA treatment attenuated cAMP accumulation in LCLs. However, while lymphoblasts show paradoxical responses to neurons and glia, patient-derived lymphoblasts appear to carry potential depression biomarkers making them an important tool for studying precision medicine in depressive patients. Furthermore, these data validate usefulness of n-3 PUFAs in treatment for depression.

Relationship of Pain Catastrophizing With Urinary Biomarkers in Women With Bladder Pain Syndrome

OBJECTIVES

Brain-derived neurotrophic factor (BDNF) has been implicated in central neurological processes. We hypothesize that greater pain catastrophizing is associated with higher urinary BDNF levels in women with bladder pain syndrome.

METHODS

A secondary analysis of a database of women with urinary urgency was conducted. We identified women who met AUA criteria of bladder pain syndrome. Urinary symptoms, pain catastrophizing, and neuropathic pain were measured using the Female Genitourinary Pain Index, Pain Catastrophizing Scale and painDETECT questionnaires respectively. The relationship of the catastrophizing score with urinary BDNF (primary outcome) and other urinary biomarkers, including nerve growth factor (NGF), vascular endothelial growth factor (VEGF), and osteopontin, was evaluated using univariable and multivariable analyses.

RESULTS

In 62 women with bladder pain syndrome, 15 (24%) reported pain catastrophizing symptoms (Pain Catastrophizing Scale score >30). Higher catastrophizing scores were associated with worse urinary symptoms, greater pelvic pain, greater neuropathic pain, and worse quality of life scores (all P < 0.01). On multivariable analysis, after controlling for age, body mass index and urinary symptoms, a higher pain catastrophizing score was associated with lower BDNF (P = 0.04) and lower VEGF levels (P = 0.03). Urinary urgency was associated with a higher NGF level (P = 0.04) while bladder pain was associated with higher levels of NGF (P = 0.03) and VEGF (P = 0.01).

CONCLUSIONS

Neuroinflammatory mechanisms contribute to the central processing of pain in women with bladder pain syndrome. Worse urinary symptoms are associated with higher NGF and VEGF levels, but worse pain catastrophizing is associated with lower BDNF and VEGF levels. Urinary BDNF levels may be useful in phenotyping women who have central augmentation of pain processing.

Sequential perturbations to mouse corticogenesis following in utero maternal immune activation

In utero exposure to maternal immune activation (MIA) is an environmental risk factor for neurodevelopmental and neuropsychiatric disorders. Animal models provide an opportunity to identify mechanisms driving neuropathology associated with MIA. We performed time-course transcriptional profiling of mouse cortical development following induced MIA via poly(I:C) injection at E12.5. MIA-driven transcriptional changes were validated via protein analysis, and parallel perturbations to cortical neuroanatomy were identified via imaging. MIA-induced acute upregulation of genes associated with hypoxia, immune signaling, and angiogenesis, by 6 hr following exposure. This acute response was followed by changes in proliferation, neuronal and glial specification, and cortical lamination that emerged at E14.5 and peaked at E17.5. Decreased numbers of proliferative cells in germinal zones and alterations in neuronal and glial populations were identified in the MIA-exposed cortex. Overall, paired transcriptomic and neuroanatomical characterization revealed a sequence of perturbations to corticogenesis driven by mid-gestational MIA.

Vascular endothelial growth factor in major depressive disorder, schizophrenia, and bipolar disorder: A network meta-analysis

The peripheral levels of vascular endothelial growth factor (VEGF) have been studied in major psychiatric diseases compared with healthy controls (HCs), but the results were inconsistent. Moreover, few studies have compared VEGF levels between these psychiatric diseases. The aim of the present study was to compare blood VEGF levels in major depressive disorder (MDD), schizophrenia (SCZ), bipolar disorder either in a manic episode, a depressive episode, or a euthymic state, and HC. We supposed that VEGF levels may be elevated in some of these diseases as a potential biomarker. In this study, forty-four studies with 6343 participants were included, and network meta-analysis was used to synthesize evidence from both direct and indirect comparisons. The main analysis showed that no significant differences were found between these groups. Subgroup analysis found that patients with MDD may have higher blood VEGF levels than patients with SCZ when the levels were measured through ELISA, and VEGF levels were increased in medication-treated MDD patients compared with HCs. Taken together, blood VEGF levels may be unaltered in these psychiatric disorders, while detection of VEGF in blood by ELISA may a feasible way to distinguish MDD and SCZ. Further replicated studies with larger samples are needed.

Altered peripheral blood compounds in drug-naïve first-episode patients with either schizophrenia or major depressive disorder: a meta-analysis

IMPORTANCE

Schizophrenia and major depressive disorder (MDD) are associated with increased risks of immunologic disease and metabolic syndrome. It is unclear to what extent growth, immune or glucose dysregulations are similarly present in these disorders without the influence of treatment or chronicity.

OBJECTIVE

To conduct a meta-analysis investigating whether there are altered peripheral growth, immune or glucose metabolism compounds in drug-naïve first-episode patients with schizophrenia or MDD compared with controls.

DATA SOURCES AND STUDY SELECTION

Case-control studies reporting compound measures in drug-naïve first-episode patients with schizophrenia or MDD compared with controls in the Embase, PubMed and PsycINFO databases.

DATA EXTRACTION AND SYNTHESIS

Two independent authors extracted data for a random-effects meta-analysis.

MAIN OUTCOMES AND MEASURES

Peripheral growth, immune or glucose metabolism compounds in schizophrenia or MDD compared with controls. Standardized mean differences were quantified with Hedges' g (g).

RESULTS

74 studies were retrieved comprising 3453 drug-naïve first-episode schizophrenia patients and 4152 controls, and 29 studies were retrieved comprising 1095 drug-naïve first-episode MDD patients and 1399 controls. Growth factors: brain-derived neurotrophic factor (BDNF) (g = -0.77, P < .001) and nerve growth factor (NGF) (g = -2.51, P = .03) were decreased in schizophrenia. For MDD, we observed a trend toward decreased BDNF (g = -0.47, P = .19) and NGF (g = -0.33, P = .08) levels, and elevated vascular endothelial growth factor levels (g = 0.40, P = .03). Immune factors: interleukin (IL)-6 (g = 0.95, P < .001), IL-8 (g = 0.59, P = .001) and tumor necrosis factor alpha (TNFα) (g = 0.48, P = .002) were elevated in schizophrenia. For C-reactive protein (CRP) (g = 0.57, P = .09), IL-4 (g = 0.44, P = .10) and interferon gamma (g = 0.33, P = .11) we observed a trend toward elevated levels in schizophrenia. In MDD, IL-6 (g = 0.62, P = .007), TNFα (g = 1.21, P < .001), CRP (g = 0.53, P < .001), IL-1β (g = 1.52, P = .009) and IL-2 (g = 4.41, P = .04) were elevated, whereas IL-8 (g = -0.84, P = .01) was decreased. The fasting glucose metabolism factors glucose (g = 0.24, P = .003) and insulin (g = 0.38, P = .003) were elevated in schizophrenia.

CONCLUSIONS AND RELEVANCE

Both schizophrenia and MDD show alterations in growth and immune factors from disease onset. An altered glucose metabolism seems to be present from onset in schizophrenia. These findings support efforts for further research into transdiagnostic preventive strategies and augmentation therapy for those with immune or metabolic dysfunctions.

Major depression accompanied with inflammation and multiple cytokines alterations: Evidences from clinical patients to macaca fascicularis and LPS-induced depressive mice model

BACKGROUND

Inflammation progress has been consistently implicated in the pathophysiology of major depressive disorder (MDD). However, the underlying mechanism of inflammation and depressive symptoms still far from being fully elucidated. In addition, studies on emotional disorders could also benefit from model of the non-human primates. To explore the difference of serum multi-cytokines levels among the MDD patients and depressed macaca fascicularis as well as LPS-treated mice, thus may find the reliable potential biomarkers for MDD.

METHODS

Serum multi-cytokines levels among MDD patients (n = 44) and depressed macaca fascicularis (n = 6) together with controls (n = 22 for human, n = 6 for macaques) were detected by the Bio-Plex cytokines panel. Then five of these serum cytokines in LPS-treated mice were measured via ELISA. Furthermore, these cytokines protein expressions were validated by western blotting in three depression-related regions of LPS-treated mice.

RESULTS

Here, we found that MDD patients displayed increased concentration of 13 proinflammatory and anti-inflammatory cytokines accompanied with one decreased cytokine in peripheral serum. Meanwhile, the naturally occurring depression (NOD) macaca fascicularis merely exhibited elevated concentration of 4 peripheral cytokines (IL-6, IL-8, MCP-1, VEGF), which were in accordance with the outcomes of MDD patients. Importantly, the serum and brain tissues of LPS-treated mice also emerged similar cytokines alterations.

CONCLUSION

In summary, our findings strengthen the evidence that cytokines were associated with the depression, and the IL-6 and VEGF may as predictive biomarkers for novel diagnostic as well as therapeutic of depression. The hypothalamus may as a key brain region involve in the inflammatory related depressive-like behaviors.

Acute exposure to low-level light at night is sufficient to induce neurological changes and depressive-like behavior

The advent and wide-spread adoption of electric lighting over the past century has profoundly affected the circadian organization of physiology and behavior for many individuals in industrialized nations; electric lighting in homes, work environments, and public areas have extended daytime activities into the evening, thus, increasing night-time exposure to light. Although initially assumed to be innocuous, chronic exposure to light at night (LAN) is now associated with increased incidence of cancer, metabolic disorders, and affective problems in humans. However, little is known about potential acute effects of LAN. To determine whether acute exposure to low-level LAN alters brain function, adult male, and female mice were housed in either light days and dark nights (LD; 14 h of 150 lux:10 h of 0 lux) or light days and low level light at night (LAN; 14 h of 150 lux:10 h of 5 lux). Mice exposed to LAN on three consecutive nights increased depressive-like responses compared to mice housed in dark nights. In addition, female mice exposed to LAN increased central tendency in the open field. LAN was associated with reduced hippocampal vascular endothelial growth factor-A (VEGF-A) in both male and female mice, as well as increased VEGFR1 and interleukin-1β mRNA expression in females, and reduced brain derived neurotrophic factor mRNA in males. Further, LAN significantly altered circadian rhythms (activity and temperature) and circadian gene expression in female and male mice, respectively. Altogether, this study demonstrates that acute exposure to LAN alters brain physiology and can be detrimental to well-being in otherwise healthy individuals.

Neurotrophic mechanisms underlying the rapid and sustained antidepressant actions of ketamine

Clinical and preclinical studies have demonstrated that depression, one of the most common psychiatric illnesses, is associated with reduced levels of neurotrophic factors, including brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF), contributing to neuronal atrophy in the prefrontal cortex (PFC) and hippocampus, and reduced hippocampal adult neurogenesis. Conventional monoaminergic antidepressants can block/reverse, at least partially, these deficits in part via induction of BDNF and/or VEGF, although these drugs have significant limitations, notably a time lag for therapeutic response and low response rates. Recent studies reveal that ketamine, an N-methyl-d-aspartate receptor antagonist produces rapid (within hours) and sustained (up to a week) antidepressant actions in both patients with treatment-resistant depression and rodent models of depression. Rodent studies also demonstrate that ketamine rapidly increases BDNF and VEGF release and/or expression in the medial PFC (mPFC) and hippocampus, leading to increase in the number and function of spine synapses in the mPFC and enhancement of hippocampal neurogenesis. These neurotrophic effects of ketamine are associated with the antidepressant effects of this drug. Together, these findings provide evidence for a neurotrophic mechanism underlying the rapid and sustained antidepressant actions of ketamine and pave the way for the development of rapid and more effective antidepressants with fewer side effects than ketamine.

Relationship between VEGF-related gene polymorphisms and brain morphology in treatment-naïve patients with first-episode major depressive disorder

Vascular endothelial growth factor (VEGF) is involved in the development of major depressive disorder (MDD). Recently, a genome-wide association study has revealed that four VEGF-related single nucleotide polymorphisms (SNPs) (i.e., rs4416670, rs6921438, rs6993770 and rs10738760) were independently associated with circulating VEGF levels. The current study investigated the relationship between brain volume and these four SNPs in first-episode drug-naïve MDD patients. A total of 38 first-episode drug-naïve MDD patients and 39 healthy subjects (HS) were recruited and underwent high-resolution T1-weighted imaging. Blood samples were collected from all the participants for serum VEGF assays and VEGF-related SNPs genotyping. Genotype-diagnosis interactions related to whole-brain cortical thickness and hippocampal subfield volumes were evaluated for the four SNPs. The results revealed a genotype-diagnosis interaction only for rs6921438 (i.e., the MDD patients and HS with the G/G genotype versus the MDD patients and HS with A-carrier genotype) in the subiculum of the left hippocampus (p < 0.05), and not the other SNPs. There was a volume reduction in the left subiculum of G/G genotype patients compared with the other groups. The "hypochondriasis" scores of the HAMD-17 scale were significantly higher in the G/G genotype patients than the A-carrier genotype patients. The association was observed between VEGF-related SNP rs6921438 and subiculum atrophy in first-episode drug-naïve MDD patients.

Role of Neuronal VEGF Signaling in the Prefrontal Cortex in the Rapid Antidepressant Effects of Ketamine

OBJECTIVE

The N-methyl-d-aspartate receptor antagonist ketamine produces rapid and sustained antidepressant actions even in patients with treatment-resistant depression. Vascular endothelial growth factor (VEGF) has been implicated in the effects of conventional monoamine-based antidepressants, but the role of VEGF in the rapid antidepressant actions of ketamine remains unclear. The authors examined whether neuronal VEGF signaling in the medial prefrontal cortex (mPFC) mediates the rapid antidepressant actions of ketamine.

METHODS

The authors used a combination of approaches, including conditional, neuron-specific knockout of VEGF or its receptor, Flk-1; antibody neutralization; viral-mediated knockdown of Flk-1; and pharmacological inhibitors. Further in vitro and in vivo experiments were performed to examine whether neuronal VEGF signaling was required for the neurotrophic and synaptogenic actions of ketamine that underlie its behavioral actions.

RESULTS

The behavioral actions of systemic ketamine are blocked by forebrain excitatory neuron-specific deletion of either VEGF or Flk-1 or by intra-mPFC infusion of a VEGF neutralizing antibody. Moreover, intra-mPFC infusions of VEGF are sufficient to produce rapid ketamine-like behavioral actions, and these effects are blocked by neuron-specific Flk-1 deletion. The results also show that local knockdown of Flk-1 in mPFC excitatory neurons in adulthood blocks the behavioral effects of systemic ketamine. Moreover, inhibition of neuronal VEGF signaling blocks the neurotrophic and synaptogenic effects of ketamine.

CONCLUSIONS

Together, these findings indicate that neuronal VEGF-Flk-1 signaling in the mPFC plays an essential role in the antidepressant actions of ketamine.

Neuroinflammation and aberrant hippocampal plasticity in a mouse model of emotional stress evoked by exposure to ultrasound of alternating frequencies

Emotional stress is a form of stress evoked by processing negative mental experience rather than an organic or physical disturbance and is a frequent cause of neuropsychiatric pathologies, including depression. Susceptibility to emotional stress is commonly regarded as a human-specific trait that is challenging to model in other species. Recently, we showed that a 3-week-long exposure to ultrasound of unpredictable alternating frequencies within the ranges of 20-25 kHz and 25-45 kHz can induce depression-like characteristics in laboratory mice and rats. In an anti-depressant sensitive manner, exposure decreases sucrose preference, elevates behavioural despair, increases aggression, and alters serotonin-related gene expression. To further investigate this paradigm, we studied depression/distress-associated markers of neuroinflammation, neuroplasticity, oxidative stress and the activity of glycogen synthase kinase-3 (GSK-3) isoforms in the hippocampus of male mice. Stressed mice exhibited a decreased density of Ki67-positive and DCX-positive cells in the subgranular zone of hippocampus, and altered expression of brain-derived neurotrophic factor (BDNF), its receptor TrkB, and anti-apoptotic protein kinase B phosphorylated at serine 473 (AktpSer473). The mice also exhibited increased densities of Iba-1-positive cells, increased oxidative stress, increased levels of interleukin-1β (IL-1β), interleukin-6 (IL-6) in the hippocampus and plasma, and elevated activity of GSK-3 isoforms. Together, the results of our investigation have revealed that unpredictable alternating ultrasound evokes behavioural and molecular changes that are characteristic of the depressive syndrome and validates this new and simple method of modeling emotional stress in rodents.

Antidepressant medication and ocular factors in association with the need for anti-VEGF retreatment in neovascular age-related macular degeneration

BACKGROUND/AIMS

Vascular endothelial growth factor (VEGF) is a key player in the pathogenesis of neovascular age-related macular degeneration (nAMD) and is also involved in the final common pathway of antidepressant medication. This study investigated the relationship between the need for anti-VEGF retreatment in patients with nAMD and antidepressant medication, and the potential impact of ocular structural factors.

METHODS

Data from two identical prospective 2-year treatment protocols using ranibizumab or aflibercept in a variable-dosing regimen ('Observe-and-Plan') were analysed. Retreatment requirement was compared with antidepressant medication intake (primary outcome) and a variety of ocular factors from baseline and from month 3 response (secondary outcomes), using univariate and multivariate analyses.

RESULTS

Of the 206 included patients (227 eyes), 19 were on antidepressant medication. Their nAMD eyes significantly more often had pigment epithelium detachment (PED, p=0.04). Multivariate analysis revealed a significant association between anti-VEGF retreatment requirement and antidepressant medication use (p=0.027), as well as thicker central retinal thickness at month 3 (p<0.0001) and month 3 PED height (p=0.001).

CONCLUSION

This study provides evidence that treatment with antidepressant medication increases the anti-VEGF retreatment requirement in patients with nAMD, possibly through the interplay of antidepressant medication, depression status and VEGF levels.

Blood-brain barrier regulation in psychiatric disorders

The blood-brain barrier (BBB) is a dynamic interface between the peripheral blood supply and the cerebral parenchyma, controlling the transport of material to and from the brain. Tight junctions between the endothelial cells of the cerebral microvasculature limit the passage of large, negatively charged molecules via paracellular diffusion whereas transcellular transportation across the endothelial cell is controlled by a number of mechanisms including transporter proteins, endocytosis, and diffusion. Here, we review the evidence that perturbation of these processes may underlie the development of psychiatric disorders including schizophrenia, autism spectrum disorder (ASD), and affective disorders. Increased permeability of the BBB appears to be a common factor in these disorders, leading to increased infiltration of peripheral material into the brain culminating in neuroinflammation and oxidative stress. However, although there is no common mechanism underpinning BBB dysfunction even within each particular disorder, the tight junction protein claudin-5 may be a clinically relevant target given that both clinical and pre-clinical research has linked it to schizophrenia, ASD, and depression. Additionally, we discuss the clinical significance of the BBB in diagnosis (genetic markers, dynamic contrast-enhanced-magnetic resonance imaging, and blood biomarkers) and in treatment (drug delivery).

Genome-wide analysis in UK Biobank identifies four loci associated with mood instability and genetic correlation with major depressive disorder, anxiety disorder and schizophrenia

Mood instability is a core clinical feature of affective and psychotic disorders. In keeping with the Research Domain Criteria approach, it may be a useful construct for identifying biology that cuts across psychiatric categories. We aimed to investigate the biological validity of a simple measure of mood instability and evaluate its genetic relationship with several psychiatric disorders, including major depressive disorder (MDD), bipolar disorder (BD), schizophrenia, attention deficit hyperactivity disorder (ADHD), anxiety disorder and post-traumatic stress disorder (PTSD). We conducted a genome-wide association study (GWAS) of mood instability in 53,525 cases and 60,443 controls from UK Biobank, identifying four independently associated loci (on chromosomes 8, 9, 14 and 18), and a common single-nucleotide polymorphism (SNP)-based heritability estimate of ~8%. We found a strong genetic correlation between mood instability and MDD (r g = 0.60, SE = 0.07, p = 8.95 × 10-17) and a small but significant genetic correlation with both schizophrenia (r g = 0.11, SE = 0.04, p = 0.01) and anxiety disorders (r g = 0.28, SE = 0.14, p = 0.04), although no genetic correlation with BD, ADHD or PTSD was observed. Several genes at the associated loci may have a role in mood instability, including the DCC netrin 1 receptor (DCC) gene, eukaryotic translation initiation factor 2B subunit beta (eIF2B2), placental growth factor (PGF) and protein tyrosine phosphatase, receptor type D (PTPRD). Strengths of this study include the very large sample size, but our measure of mood instability may be limited by the use of a single question. Overall, this work suggests a polygenic basis for mood instability. This simple measure can be obtained in very large samples; our findings suggest that doing so may offer the opportunity to illuminate the fundamental biology of mood regulation.

Multitarget botanical pharmacotherapy in major depression: a toxic brain hypothesis

A significant number of patients with major depression do not respond optimally to current antidepressant drugs. As depression is likely to be a heterogeneous disorder, it is possible that existing neurotransmitter-based antidepressant drugs do not fully address other pathologies that may exist in certain cases. Biological pathologies related to depression that have been proposed and studied extensively include inflammation and immunology, hypercortisolemia, oxidative stress, and impaired angiogenesis. Such pathologies may induce neurodegeneration, which in turn causes cognitive impairment, a symptom increasingly being recognized in depression. A neurotoxic brain hypothesis unifying all these factors may explain the heterogeneity of depression as well as cognitive decline and antidepressant drug resistance in some patients. Compared with neurotransmitter-based antidepressant drugs, many botanical compounds in traditional medicine used for the treatment of depression and its related symptoms have been discovered to be anti-inflammatory, immunoregulatory, anti-infection, antioxidative, and proangiogenic. Some botanical compounds also exert actions on neurotransmission. This multitarget nature of botanical medicine may act through the amelioration of the neurotoxic brain environment in some patients resistant to neurotransmitter-based antidepressant drugs. A multitarget multidimensional approach may be a reasonable solution for patients resistant to neurotransmitter-based antidepressant drugs.

Developmental pathway genes and neural plasticity underlying emotional learning and stress-related disorders

The manipulation of neural plasticity as a means of intervening in the onset and progression of stress-related disorders retains its appeal for many researchers, despite our limited success in translating such interventions from the laboratory to the clinic. Given the challenges of identifying individual genetic variants that confer increased risk for illnesses like depression and post-traumatic stress disorder, some have turned their attention instead to focusing on so-called "master regulators" of plasticity that may provide a means of controlling these potentially impaired processes in psychiatric illnesses. The mammalian homolog of Tailless (TLX), Wnt, and the homeoprotein Otx2 have all been proposed to constitute master regulators of different forms of plasticity which have, in turn, each been implicated in learning and stress-related disorders. In the present review, we provide an overview of the changing distribution of these genes and their roles both during development and in the adult brain. We further discuss how their distinct expression profiles provide clues as to their function, and may inform their suitability as candidate drug targets in the treatment of psychiatric disorders.