Biomarkers in major depressive disorder: the role of mass spectrometry

Development of a Novel Web Camera-Based Contact-Free Major Depressive Disorder Screening System Using Autonomic Nervous Responses Induced by a Mental Task and Its Clinical Application

Background

To increase the consultation rate of potential major depressive disorder (MDD) patients, we developed a contact-type fingertip photoplethysmography-based MDD screening system. With the outbreak of SARS-CoV-2, we developed an alternative to contact-type fingertip photoplethysmography: a novel web camera-based contact-free MDD screening system (WCF-MSS) for non-contact measurement of autonomic transient responses induced by a mental task.

Methods

The WCF-MSS measures time-series interbeat intervals (IBI) by monitoring color tone changes in the facial region of interest induced by arterial pulsation using a web camera (1920 × 1080 pixels, 30 frames/s). Artifacts caused by body movements and head shakes are reduced. The WCF-MSS evaluates autonomic nervous activation from time-series IBI by calculating LF (0.04-0.15 Hz) components of heart rate variability (HRV) corresponding to sympathetic and parasympathetic nervous activity and HF (0.15-0.4 Hz) components equivalent to parasympathetic activities. The clinical test procedure comprises a pre-rest period (Pre-R; 140 s), mental task period (MT; 100 s), and post-rest period (Post-R; 120 s). The WCF-MSS uses logistic regression analysis to discriminate MDD patients from healthy volunteers via an optimal combination of four explanatory variables determined by a minimum redundancy maximum relevance algorithm: HF during MT (HF _MT ), the percentage change of LF from pre-rest to MT (%ΔLF_(Pre-R⇒MT) ), the percentage change of HF from pre-rest to MT (%ΔHF_(Pre-R⇒MT) ), and the percentage change of HF from MT to post-rest (%ΔHF_{(MT⇒Post-R)} ). To clinically test the WCF-MSS, 26 MDD patients (16 males and 10 females, 20-58 years) were recruited from BESLI Clinic in Tokyo, and 27 healthy volunteers (15 males and 12 females, 18-60 years) were recruited from Tokyo Metropolitan University and RICOH Company, Ltd. Electrocardiography was used to calculate HRV variables as references.

Result

The WCF-MSS achieved 73% sensitivity and 85% specificity on 5-fold cross-validation. IBI correlated significantly with IBI from reference electrocardiography (r = 0.97, p < 0.0001). Logit scores and subjective self-rating depression scale scores correlated significantly (r = 0.43, p < 0.05).

Conclusion

The WCF-MSS seems a promising contact-free MDD screening apparatus. This method enables web camera built-in smartphones to be used as MDD screening systems.

Chronic mild stress leads to aberrant glucose energy metabolism in depressed Macaca fascicularis models

BACKGROUND

Major depressive disorder (MDD) is a pathophysiologically uncharacterized mental illness with complex etiology and clinical manifestations. Rodent depression-like models have been widely used to mimic the morbid state of depression. However, research on emotional disorders can also benefit from the use of models in non-human primates, which share a wide range of genetic and social similarities with humans.

METHODS

To investigate the pathophysiological mechanisms of depression, we established two models, naturally occurring depression cynomolgus (NOD) and social plus visual isolation-induced depression cynomolgus (SVC), imitating chronic mild or acute intense stress, respectively. We used i-TRAQ (isobaric tags for relative and absolute quantitation)-based quantitative proteomics and shotgun proteomics to identify differentially expressed proteins in cerebrospinal fluid (CSF) of the two monkey models and human MDD patients. We also used DAVID and ingenuity pathway analysis (IPA) for further bioinformatic investigation.

RESULTS

In behavioral tests, NOD monkeys achieved higher scores in depression-like and anxiety-like behavioral measures, and spent more time on ingesting, thermoregulatory, and locomotive actions than SVC monkeys. A total of 902 proteins were identified by i-TRAQ, and 40 differentially expressed proteins were identified in each of the NOD-CON1 and SVC-CON2 groups. Application of DAVID revealed dysregulation of energy metabolism in the NOD group, whereas lipid metabolism and inflammatory response pathways were significantly altered in the SVC group. Use of IPA and Cytoscape showed that the oxygen species metabolic process glycolysis I/gluconeogenesis I, accompanied by downregulation of tubulin beta 3 class III (TUBB3), RAC-alpha serine/threonine-protein kinase (AKT1), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), was the most significantly affected pathway in the NOD group. Furthermore, 152 differentially expressed proteins in human MDD patients also revealed disruption of glucose energy metabolism. Significantly aberrant energy metabolism in various brain regions and the plasma and liver of chronic unpredictable mild stress rodent samples were also observed in a previous study.

CONCLUSIONS

Our results reveal for the first time the overall CSF protein profiles of two cynomolgus monkey models of depression. We propose that chronic mild stress may affect the disruption of glucose energy metabolism in NOD cynomolgus monkeys and rodents. These findings promote our understanding of the pathophysiology of MDD and may help to identify novel therapeutic targets.

Fighting against depression with TREK-1 blockers: Past and future. A focus on spadin

Depression is a devastating mood disorder and a leading cause of disability worldwide. Depression affects approximately one in five individuals in the world and represents heavy economic and social burdens. The neurobiological mechanisms of depression are not fully understood, but evidence highlights the role of monoamine neurotransmitter balance. Several antidepressants (ADs) are marketed to treat depression and related mood disorders. However, despite their efficacy, they remain nonspecific and unsafe because they trigger serious adverse effects. Therefore, developing new molecules for new targets in depression has become a real necessity. Eight years ago, spadin was described as a natural peptide with AD properties. This 17-amino acid peptide blocks TREK-1 channels, an original target in depression. Compared to the classical AD drugs such as fluoxetine, which requires 3-4 weeks for the AD effect to manifest, spadin acts rapidly within only 4 days of treatment. The AD properties are associated with increased neurogenesis and synaptogenesis in the brain. Despite the advantages of this fast-acting AD, the in vivo stability is weak and does not last for >7 h. The present review summarizes different strategies such as retro-inverso strategy, cyclization, and shortening the spadin sequence that has led to the development and optimization of spadin as an AD. Shortened spadin analogs present increased inhibition potency for TREK-1, an improved AD activity, and prolonged in vivo bioavailability. Finally, we also discuss about other inhibitors of TREK-1 channels with a proven efficacy in treating depression in the clinic, such as fluoxetine.

Inherent vulnerabilities in monoaminergic pathways predict the emergence of depressive impairments in an animal model of chronic epilepsy

The objective was to determine whether the depression comorbid with epilepsy could be predicted based on inherent premorbid patterns of monoaminergic transmission. In male Wistar rats, despair-like and anhedonia-like behaviors were examined using forced swimming and taste preference tests, respectively. Serotonergic raphe nucleus (RN)-prefrontal cortex (PFC) and dopaminergic ventral tegmental area (VTA)-nucleus accumbens (NAcc) pathways were interrogated by fast scan cyclic voltammetry (FSCV). The assays were performed before and 2 months after pilocarpine status epilepticus. In a subset of naive rats, FSCV, coupled with the intensity-dependent stimulation paradigm, detected specific deviations in each pathway (six rats for RN-PFC and seven rats for VTA-NAcc, with overlap in two, of 19 total subjects) in the absence of behavioral impairments. During epilepsy, animals with preexisting deviations in RN-PFC invariably developed despair, and rats with deviations in VTA-NAcc developed anhedonia. Serotonergic and dopaminergic pathways, respectively, showed signs of explicit deterioration. We suggest that epilepsy triggers decompensations in the already vulnerable depression-relevant neuronal circuits, which culminate in depression. The established connection between the identified specific signatures in monoamine transmission in naive rats and specific symptoms of epilepsy-associated depression may help in understanding causes of comorbidity and in developing its early biomarkers.

Recent advances in applying mass spectrometry and systems biology to determine brain dynamics

INTRODUCTION

Neurological disorders encompass various pathologies which disrupt normal brain physiology and function. Poor understanding of their underlying molecular mechanisms and their societal burden argues for the necessity of novel prevention strategies, early diagnostic techniques and alternative treatment options to reduce the scale of their expected increase. Areas covered: This review scrutinizes mass spectrometry based approaches used to investigate brain dynamics in various conditions, including neurodegenerative and neuropsychiatric disorders. Different proteomics workflows for isolation/enrichment of specific cell populations or brain regions, sample processing; mass spectrometry technologies, for differential proteome quantitation, analysis of post-translational modifications and imaging approaches in the brain are critically deliberated. Future directions, including analysis of cellular sub-compartments, targeted MS platforms (selected/parallel reaction monitoring) and use of mass cytometry are also discussed. Expert commentary: Here, we summarize and evaluate current mass spectrometry based approaches for determining brain dynamics in health and diseases states, with a focus on neurological disorders. Furthermore, we provide insight on current trends and new MS technologies with potential to improve this analysis.

Is there Progress? An Overview of Selecting Biomarker Candidates for Major Depressive Disorder

Major depressive disorder (MDD) contributes to a significant worldwide disease burden, expected to be second only to heart disease by 2050. However, accurate diagnosis has been a historical weakness in clinical psychiatry. As a result, there is a demand for diagnostic modalities with greater objectivity that could improve on current psychiatric practice that relies mainly on self-reporting of symptoms and clinical interviews. Over the past two decades, literature on a growing number of putative biomarkers for MDD increasingly suggests that MDD patients have significantly different biological profiles compared to healthy controls. However, difficulty in elucidating their exact relationships within depression pathology renders individual markers inconsistent diagnostic tools. Consequently, further biomarker research could potentially improve our understanding of MDD pathophysiology as well as aid in interpreting response to treatment, narrow differential diagnoses, and help refine current MDD criteria. Representative of this, multiplex assays using multiple sources of biomarkers are reported to be more accurate options in comparison to individual markers that exhibit lower specificity and sensitivity, and are more prone to confounding factors. In the future, more sophisticated multiplex assays may hold promise for use in screening and diagnosing depression and determining clinical severity as an advance over relying solely on current subjective diagnostic criteria. A pervasive limitation in existing research is heterogeneity inherent in MDD studies, which impacts the validity of biomarker data. Additionally, small sample sizes of most studies limit statistical power. Yet, as the RDoC project evolves to decrease these limitations, and stronger studies with more generalizable data are developed, significant advances in the next decade are expected to yield important information in the development of MDD biomarkers for use in clinical settings.

Salivary proteomics and biomarkers in neurology and psychiatry

Biomarkers are greatly needed in the fields of neurology and psychiatry, to provide objective and earlier diagnoses of CNS conditions. Proteomics and other omics MS-based technologies are tools currently being utilized in much recent CNS research. Saliva is an interesting alternative biomaterial for the proteomic study of CNS disorders, with several advantages. Collection is noninvasive and saliva has many proteins. It is easier to collect than blood and can be collected by professionals without formal medical training. For psychiatric and neurological patients, supplying a saliva sample is less anxiety-provoking than providing a blood sample, and is less embarrassing than producing a urine specimen. The use of saliva as a biomaterial has been researched for the diagnosis of and greater understanding of several CNS conditions, including neurodegenerative diseases, autism, and depression. Salivary biomarkers could be used to rule out nonpsychiatric conditions that are often mistaken for psychiatric/neurological conditions, such as fibromyalgia, and potentially to assess cognitive ability in individuals with compromised brain function. As MS and omics technology advances, the sensitivity and utility of assessing CNS conditions using distal human biomaterials such as saliva is becoming increasingly possible.