Neuroplasticity pathways and protein-interaction networks are modulated by vortioxetine in rodents.

BACKGROUND: The identification of biomarkers that predict susceptibility to major depressive disorder and treatment response to antidepressants is a major challenge. Vortioxetine is a novel multimodal antidepressant that possesses pro-cognitive properties and differentiates from other conventional antidepressants on various cognitive and plasticity measures. The aim of the present study was to identify biological systems rather than single biomarkers that may underlie vortioxetine's treatment effects. RESULTS: We show that the biological systems regulated by vortioxetine are overlapping between mouse and rat in response to distinct treatment regimens and in different brain regions. Furthermore, analysis of complexes of physically-interacting proteins reveal that biomarkers involved in transcriptional regulation, neurodevelopment, neuroplasticity, and endocytosis are modulated by vortioxetine. A subsequent qPCR study examining the expression of targets in the protein-protein interactome space in response to chronic vortioxetine treatment over a range of doses provides further biological validation that vortioxetine engages neuroplasticity networks. Thus, the same biology is regulated in different species and sexes, different brain regions, and in response to distinct routes of administration and regimens. CONCLUSIONS: A recurring theme, based on the present study as well as previous findings, is that networks related to synaptic plasticity, synaptic transmission, signal transduction, and neurodevelopment are modulated in response to vortioxetine treatment. Regulation of these signaling pathways by vortioxetine may underlie vortioxetine's cognitive-enhancing properties.

Ceramic hydroxyapatite chromatography plays a critical role in bispecific antibody purification process for impurity removal.

Background: Significant challenges exist in downstream purification of bispecific antibodies (BsAbs) due to the complexity of BsAb architecture. A unique panel of mispaired species can result in a higher level of product-related impurities. In addition to process-related impurities such as host cell proteins (HCPs) and residual DNA (resDNA), these product-related impurities must be separated from the targeted BsAb product to achieve high purity. Therefore, development of an efficient and robust chromatography purification process is essential to ensure the safety, quality, purity and efficacy of BsAb products that consequently meet regulatory requirements for clinical trials and commercialization. Methods: We have developed a robust downstream BsAb process consisting of a mixed-mode ceramic hydroxyapatite (CHT) chromatography step, which offers unique separation capabilities tailored to BsAbs, and assessed impurity clearance. Results: We demonstrate that the CHT chromatography column provides additional clearance of low molecular weight (LMW) and high molecular weight (HMW) species that cannot be separated by other chromatography columns such as ion exchange for a particular BsAb, resulting in ≥98% CE-SDS (non-reduced) purity. Moreover, through Polysorbate-80 (PS-80) spiking and LC-MS HCP assessments, we reveal complete clearance of potential PS-80-degrading HCP populations in the CHT eluate product pool. Conclusions: In summary, these results demonstrate that CHT mixed-mode chromatography plays an important role in separation of product- and process-related impurities in the BsAb downstream process.

Chronic vortioxetine treatment in rodents modulates gene expression of neurodevelopmental and plasticity markers.

The multimodal antidepressant vortioxetine displays an antidepressant profile distinct from those of conventional selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) and possesses cognitive-enhancing properties in preclinical and clinical studies. Recent studies have begun to investigate molecular mechanisms that may differentiate vortioxetine from other antidepressants. Acute studies in adult rats and chronic studies in a middle-aged mouse model reveal upregulation of several markers that play a central role in synaptic plasticity. However, the effect of chronic vortioxetine treatment on expression of neuroplasticity and neurodevelopmental biomarkers in naïve rats has not been evaluated. In the present study, we demonstrate that vortioxetine at a range of doses regulates expression of genes associated with plasticity in the frontal cortex, hippocampus, region encompassing the amygdala, as well as in blood, and displays similar effects relative to the SSRI fluoxetine in adult naïve rats. These genes encode immediate early genes (IEGs), translational regulators, and the neurodevelopmental marker Sema4g. Similar findings detected in brain regions and in blood provide a potential translational impact, and vortioxetine appears to consistently regulate signaling in these networks of neuroplasticity and developmental markers.

Vortioxetine promotes maturation of dendritic spines in vitro: A comparative study in hippocampal cultures.

Cognitive dysfunction is prevalent in patients with major depressive disorder (MDD), and cognitive impairments can persist after relief of depressive symptoms. The multimodal-acting antidepressant vortioxetine is an antagonist at 5-HT3, 5-HT7, and 5-HT1D receptors, a partial agonist at 5-HT1B receptors, an agonist at 5-HT1A receptors, and an inhibitor of the serotonin (5-HT) transporter (SERT) and has pro-cognitive properties. In preclinical studies, vortioxetine enhances long-term potentiation (LTP), a cellular correlate of neuroplasticity, and enhances memory in various cognitive tasks. However, the molecular mechanisms by which vortioxetine augments LTP and memory remain unknown. Dendritic spines are specialized, actin-rich microdomains on dendritic shafts and are major sites of most excitatory synapses. Since dendritic spine remodeling is implicated in synaptic plasticity and spine size dictates the strength of synaptic transmission, we assessed if vortioxetine, relative to other antidepressants including ketamine, duloxetine, and fluoxetine, plays a role in the maintenance of dendritic spine architecture in vitro. We show that vortioxetine, ketamine, and duloxetine induce spine enlargement. However, only vortioxetine treatment increased the number of spines in contact with presynaptic terminals. In contrast, fluoxetine had no effect on spine remodeling. These findings imply that the various 5-HT receptor mechanisms of vortioxetine may play a role in its effect on spine dynamics and in increasing the proportion of potentially functional synaptic contacts.

Vortioxetine promotes early changes in dendritic morphology compared to fluoxetine in rat hippocampus.

Preclinical studies reveal that the multimodal antidepressant vortioxetine enhances long-term potentiation and dendritic branching compared to a selective serotonin reuptake inhibitor (SSRI). In the present study, we investigated vortioxetine׳s effects on spines and dendritic morphology in rat hippocampus at two time points compared to the SSRI, fluoxetine. Rats were dosed for 1 and 4 weeks with vortioxetine and fluoxetine at doses relevant for antidepressant activity. Dendritic morphology of pyramidal neurons (i.e., dendritic length, dendritic branch, spine number and density, and Sholl analysis) was examined in Golgi-stained sections from hippocampal CA1. After 1 week of treatment, vortioxetine significantly increased spine number (apical and basal dendrites), spine density (only basal), dendritic length (only apical), and dendritic branch number (apical and basal), whereas fluoxetine had no effect. After 4 weeks of treatment, vortioxetine significantly increased all measures of dendritic spine morphology as did fluoxetine except for spine density of basal dendrites. The number of intersections in the apical and basal dendrites was also significantly increased for both treatments after 4 weeks compared to control. In addition, 4 weeks of vortioxetine treatment, but not fluoxetine, promoted a decrease in spine neck length. In conclusion, 1-week vortioxetine treatment induced changes in spine number and density and dendritic morphology, whereas an equivalent dose of fluoxetine had no effects. Decreased spine neck length following 4-week vortioxetine treatment suggests a transition to mature spine morphology. This implies that vortioxetine׳s effects on spine and dendritic morphology are mediated by mechanisms that go beyond serotonin reuptake inhibition.

Histamine may contribute to vortioxetine's procognitive effects; possibly through an orexigenic mechanism.

Vortioxetine is a novel multimodal antidepressant that acts as a serotonin (5-HT)3, 5-HT7, and 5-HT1D receptor antagonist; 5-HT1B receptor partial agonist; 5-HT1A receptor agonist; and 5-HT transporter inhibitor in vitro. In preclinical and clinical studies vortioxetine demonstrates positive effects on cognitive dysfunction. Vortioxetine's effect on cognitive function likely involves the modulation of several neurotransmitter systems. Acute and chronic administration of vortioxetine resulted in changes in histamine concentrations in microdialysates collected from the rat prefrontal cortex and ventral hippocampus. Based on these results and a literature review of the current understanding of the interaction between the histaminergic and serotonergic systems and the role of histamine on cognitive function, we hypothesize that vortioxetine through an activation of the orexinergic system stimulates the tuberomammilary nucleus and enhances histaminergic neurotransmission, which contributes to vortioxetine's positive effects on cognitive function.

A critical evaluation of the activity-regulated cytoskeleton-associated protein (Arc/Arg3.1)'s putative role in regulating dendritic plasticity, cognitive processes, and mood in animal models of depression.

Major depressive disorder (MDD) is primarily conceptualized as a mood disorder but cognitive dysfunction is also prevalent, and may limit the daily function of MDD patients. Current theories on MDD highlight disturbances in dendritic plasticity in its pathophysiology, which could conceivably play a role in the production of both MDD-related mood and cognitive symptoms. This paper attempts to review the accumulated knowledge on the basic biology of the activity-regulated cytoskeleton-associated protein (Arc or Arg3.1), its effects on neural plasticity, and how these may be related to mood or cognitive dysfunction in animal models of MDD. On a cellular level, Arc plays an important role in modulating dendritic spine density and remodeling. Arc also has a close, bidirectional relationship with postsynaptic glutamate neurotransmission, since it is stimulated by multiple glutamatergic receptor mechanisms but also modulates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor internalization. The effects on AMPA receptor trafficking are likely related to Arc's ability to modulate phenomena such as long-term potentiation, long-term depression, and synaptic scaling, each of which are important for maintaining proper cognitive function. Chronic stress models of MDD in animals show suppressed Arc expression in the frontal cortex but elevation in the amygdala. Interestingly, cognitive tasks depending on the frontal cortex are generally impaired by chronic stress, while those depending on the amygdala are enhanced, and antidepressant treatments stimulate cortical Arc expression with a timeline that is reminiscent of the treatment efficacy lag observed in the clinic or in preclinical models. However, pharmacological treatments that stimulate regional Arc expression do not universally improve relevant cognitive functions, and this highlights a need to further refine our understanding of Arc on a subcellular and network level.

Treatment of cognitive dysfunction in major depressive disorder--a review of the preclinical evidence for efficacy of selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors and the multimodal-acting antidepressant vortioxetine.

Although major depressive disorder is primarily considered a mood disorder, depressed patients commonly present with clinically significant cognitive dysfunction that may add to their functional disability. This review paper summarizes the available preclinical data on the effects of antidepressants, including monoamine reuptake inhibitors and the multimodal antidepressant vortioxetine, in behavioral tests of cognition such as cognitive flexibility, attention, and memory, or in potentially cognition-relevant mechanistic assays such as electroencephalography, in vivo microdialysis, in vivo or in vitro electrophysiology, and molecular assays related to neurogenesis or synaptic sprouting. The available data are discussed in context with clinically relevant doses and their relationship to target occupancy levels, in order to evaluate the translational relevance of preclinical doses used during testing. We conclude that there is preclinical evidence suggesting that traditional treatment with monoamine reuptake inhibitors can induce improved cognitive function, for example in cognitive flexibility and memory, and that the multimodal-acting antidepressant vortioxetine may have some advantages by comparison to these treatments. However, the translational value of the reviewed preclinical data can be questioned at times, due to the use of doses outside the therapeutically-relevant range, the lack of data on target engagement or exposure, the tendency to investigate acute rather than long term antidepressant administration, and the trend towards using normal rodents rather than models with translational relevance for depression. Finally, several suggestions are made for advancing this field, including expanded use of target occupancy assessments in preclinical and clinical experiments, and the use of translationally valuable techniques such as electroencephalography.