Differential and paradoxical roles of new-generation antidepressants in primary astrocytic inflammation

Escitalopram moderately outperforms citalopram towards anti-neuroinflammation and neuroprotection in 6-hydroxydopamine-induced mouse model of Parkinson's disease

Citalopram and escitalopram are structurally close-related antidepressants and both forms are widely used in the world. We aimed to comparatively evaluate the anti-neuroinflammatory and neuroprotective effects of escitalopram and citalopram in Parkinson's disease (PD) mouse model. Mice were randomly divided into six groups and received 6-hydroxydopamine (6-OHDA) or vehicle administration. The mice were then treated with escitalopram, citalopram or saline for consecutive 7 days. Behaviors, neuroinflammation, neurotransmitters, and neurotoxicity were assessed. Results showed that citalopram but not escitalopram worsened body weight loss and increased freezing time in the PD mice. Both drugs had no impact on the anxiety-like behaviors but ameliorated the depressive-like behaviors as in elevated plus maze and sucrose splash tests. Escitalopram but not citalopram ameliorated motor discoordination in the PD mice as in rotarod test. In accordance, escitalopram but not citalopram attenuated the 6-OHDA-induced nigrostriatal dopaminergic loss. Further mechanistic investigations showed that both drugs mitigated activations of microglia and astrocytes and/or levels of pro-inflammatory cytokines in the PD mice, but escitalopram showed appreciably better effects in the substantia nigra. Neurotransmitter examination in the prefrontal cortex suggested that the two drugs had comparable effects on the disturbed neurotransmitters in the PD mice, but citalopram was prone to disrupt certain normal homeostasis. In conclusion, escitalopram is moderately superior than citalopram to suppress neuroinflammation and to protect against dopaminergic neuronal death and motor discoordination in the 6-OHDA-induced PD mice. Our findings imply that escitalopram shall be prescribed with priority over citalopram to treat PD patients with depression as escitalopram may meanwhile provide greater additional benefits to the patients.

Unveiling the hidden pathways: Exploring astrocytes as a key target for depression therapy

Depressive disorders are widely debilitating psychiatric disease. Despite the considerable progress in the field of depression therapy, extensive research spanning many decades has failed to uncover pathogenic pathways that might aid in the creation of long-acting and rapid-acting antidepressants. Consequently, it is imperative to reconsider existing approaches and explore other targets to improve this area of study. In contemporary times, several scholarly investigations have unveiled that persons who have received a diagnosis of depression, as well as animal models employed to study depression, demonstrate a decrease in both the quantity as well as density of astrocytes, accompanied by alterations in gene expression and morphological attributes. Astrocytes rely on a diverse array of channels and receptors to facilitate their neurotransmitter transmission inside tripartite synapses. This study aimed to investigate the potential processes behind the development of depression, specifically focusing on astrocyte-associated neuroinflammation and the involvement of several molecular components such as connexin 43, potassium channel Kir4.1, aquaporin 4, glutamatergic aspartic acid transporter protein, SLC1A2 or GLT-1, glucocorticoid receptors, 5-hydroxytryptamine receptor 2B, and autophagy, that localized on the surface of astrocytes. The study also explores novel approaches in the treatment of depression, with a focus on astrocytes, offering innovative perspectives on potential antidepressant medications.

Sertraline associated with gold nanoparticles reduce cellular toxicity and induce sex-specific responses in behavior and neuroinflammation biomarkers in a mouse model of anxiety

This study aimed to evaluate the effects of sertraline associated with gold nanoparticles (AuNPs) in vitro cell viability and in vivo behavior and inflammatory biomarkers in a mouse model of anxiety. Sertraline associated with AuNPs were synthesized and characterized. For the in vitro study, NIH3T3 and HT-22 cells were treated with different doses of sertraline, AuNPs, and sertraline + AuNPs and their viability was evaluated using the MTT assay. For the in vivo study, pregnant Swiss mice were administered a single dose of lipopolysaccharide (LPS) on the ninth day of gestation. The female and male offspring were divided into five treatment groups on PND 60 and administered chronic treatment for 28 days. The animals were subjected to behavioral testing and were subsequently euthanized. Their brains were collected and analyzed for inflammatory biomarkers. Sertraline associated with AuNPs exhibited significant changes in surface characteristics and increased diameters. Different doses of sertraline + AuNPs showed higher cell viability in NIH3T3 and HT-22 cells compared with sertraline alone. The offspring of LPS-treated dams exhibited anxiety-like behavior and neuroinflammatory biomarker changes during adulthood, which were ameliorated via sertraline + AuNPs treatment. The treatment response was sex-dependent and brain region-specific. These results suggest that AuNPs, which demonstrate potential to bind to other molecules, low toxicity, and reduced inflammation, can be synergistically used with sertraline to improve drug efficacy and safety by decreasing neuroinflammation and sertraline toxicity.

Exploring Astrocyte-Mediated Mechanisms in Sleep Disorders and Comorbidity

Astrocytes, the most abundant cells in the brain, are integral to sleep regulation. In the context of a healthy neural environment, these glial cells exert a profound influence on the sleep-wake cycle, modulating both rapid eye movement (REM) and non-REM sleep phases. However, emerging literature underscores perturbations in astrocytic function as potential etiological factors in sleep disorders, either as protopathy or comorbidity. As known, sleep disorders significantly increase the risk of neurodegenerative, cardiovascular, metabolic, or psychiatric diseases. Meanwhile, sleep disorders are commonly screened as comorbidities in various neurodegenerative diseases, epilepsy, and others. Building on existing research that examines the role of astrocytes in sleep disorders, this review aims to elucidate the potential mechanisms by which astrocytes influence sleep regulation and contribute to sleep disorders in the varied settings of brain diseases. The review emphasizes the significance of astrocyte-mediated mechanisms in sleep disorders and their associated comorbidities, highlighting the need for further research.

Imidazoles as Serotonin Receptor Modulators for Treatment of Depression: Structural Insights and Structure-Activity Relationship Studies

Serotoninergic signaling is identified as a crucial player in psychiatric disorders (notably depression), presenting it as a significant therapeutic target for treating such conditions. Inhibitors of serotoninergic signaling (especially selective serotonin reuptake inhibitors (SSRI) or serotonin and norepinephrine reuptake inhibitors (SNRI)) are prominently selected as first-line therapy for the treatment of depression, which benefits via increasing low serotonin levels and norepinephrine by blocking serotonin/norepinephrine reuptake and thereby increasing activity. While developing newer heterocyclic scaffolds to target/modulate the serotonergic systems, imidazole-bearing pharmacophores have emerged. The imidazole-derived pharmacophore already demonstrated unique structural characteristics and an electron-rich environment, ultimately resulting in a diverse range of bioactivities. Therefore, the current manuscript discloses such a specific modification and structural activity relationship (SAR) of attempted derivatization in terms of the serotonergic efficacy of the resultant inhibitor. We also featured a landscape of imidazole-based development, focusing on SAR studies against the serotoninergic system to target depression. This study covers the recent advancements in synthetic methodologies for imidazole derivatives and the development of new molecules having antidepressant activity via modulating serotonergic systems, along with their SAR studies. The focus of the study is to provide structural insights into imidazole-based derivatives as serotonergic system modulators for the treatment of depression.

The impact of antidepressants on human neurodevelopment: Brain organoids as experimental tools

The use of antidepressants during pregnancy benefits the mother's well-being, but the effects of such substances on neurodevelopment remain poorly understood. Moreover, the consequences of early exposure to antidepressants may not be immediately apparent at birth. In utero exposure to selective serotonin reuptake inhibitors (SSRIs) has been related to developmental abnormalities, including a reduced white matter volume. Several reports have observed an increased incidence of autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) after prenatal exposure to SSRIs such as sertraline, the most widely prescribed SSRI. The advent of human-induced pluripotent stem cell (hiPSC) methods and assays now offers appropriate tools to test the consequences of such compounds for neurodevelopment in vitro. In particular, hiPSCs can be used to generate cerebral organoids - self-organized structures that recapitulate the morphology and complex physiology of the developing human brain, overcoming the limitations found in 2D cell culture and experimental animal models for testing drug efficacy and side effects. For example, single-cell RNA sequencing (scRNA-seq) and electrophysiological measurements on organoids can be used to evaluate the impact of antidepressants on the transcriptome and neuronal activity signatures in developing neurons. While the analysis of large-scale transcriptomic data depends on dimensionality reduction methods, electrophysiological recordings rely on temporal data series to discriminate statistical characteristics of neuronal activity, allowing for the rigorous analysis of the effects of antidepressants and other molecules that affect the developing nervous system, especially when applied in combination with relevant human cellular models such as brain organoids.

Administration of serotonin and norepinephrine reuptake inhibitors tends to have less ocular surface damage in a chronic stress-induced rat model of depression than selective serotonin reuptake inhibitors

Depressed patients who medicate with selective serotonin reuptake inhibitors (SSRIs) often report ocular dryness. Epidemiological studies have found that serotonin and norepinephrine reuptake inhibitors (SNRIs) are not risk factors for dry eye in depressed patients. However, the effect of SNRIs on the ocular surface is unknown. A depression rat model was induced by chronic unpredictable mild stress (CUMS), and SNRIs or SSRIs were administered to the rats for 3 or 6 weeks. The levels of norepinephrine (NE) and serotonin in tear fluid were tested by ELISA. The corneal fluorescence and lissamine green staining were used to evaluate ocular surface damage. NE and/or serotonin were administered to human corneal epithelial cells in vitro. RNA sequencing (RNA-seq) analysis was performed to investigate the mRNA expression profiles. Tear NE levels were higher in the SNRIs group, and ocular surface inflammation and apoptosis were significantly reduced compared to the SSRIs group. RNA-Seq indicated that NE significantly activate MAPK signaling pathway. NE can inhibit serotonin-induced activation of the NF-κB signaling pathway through α-1 adrenergic receptors and promotes the proliferation of corneal epithelial cells through activation of the MAPK signaling pathway. SNRIs administration have less ocular surface damage than SSRIs. NE protects human corneal epithelial cells from damage, and reduce inflammation on the ocular surface via activating the MAPK signaling pathway. SNRIs might be used as an appropriate treatment for depression-related DED.

Potential drugs for the treatment of Alzheimer's disease

It is well known that amyloid precursor protein (APP), the enzyme β-secretase 1 (BACE1), cyclooxygenase 2 (COX-2), nicastrin (NCT), and hyperphosphorylated tau protein (p-tau) are closely related to the development of Alzheimer's disease (AD). In addition, recent evidence shows that neuroinflammation also contributes to the pathogenesis of AD. Although the mechanism is not clearly known, such inflammation could alter the activity of the aforementioned molecules. Therefore, the use of anti-inflammatory agents could slow the progression of the disease. Nimesulide, resveratrol, and citalopram are three anti-inflammatory agents that could contribute to a decrease in neuroinflammation and consequently to a decrease in the overexpression of APP, BACE1, COX-2, NCT, and p-Tau, as they possess anti-inflammatory effects that could regulate the expression of APP, BACE1, COX-2, NCT, and p-Tau of potent pro-inflammatory markers indirectly involved in the expression of APP, BACE1, NCT, COX-2, and p-Tau; therefore, their use could be beneficial as preventive treatment as well as in the early stages of AD.

Corynoxine suppresses pancreatic cancer growth primarily via ROS-p38 mediated cytostatic effects

BACKGROUND

Pancreatic cancer is among the most common malignant tumours, and effective therapeutic strategies are still lacking. While Corynoxine (Cory) can induce autophagy in neuronal cells, it remains unclear whether Cory has anti-tumour activities against pancreatic cancer.

METHODS

Two pancreatic cancer cell lines, Patu-8988 and Panc-1, were used. Effects of Cory were evaluated by cell viability analysis, EdU staining, TUNEL assay, colony formation assay, and flow cytometry. Quantitative PCR and Western blot were performed to analyse mRNA and protein levels, respectively. In vivo anti-tumour efficacy of Cory was determined by a xenograft model.

RESULTS

Cory treatment inhibited cell proliferation, induced endoplasmic reticulum (ER) stress, and triggered apoptosis in the pancreatic cancer cell lines. CHOP knockdown-mediated inhibition of ER stress alleviated the Cory-induced apoptosis but showed a limited effect on cell viability. Cory induced cell death partially via promoting reactive oxygen species (ROS) production and activating p38 signalling. Pretreatment with ROS scavenger N-acetylcysteine and p38 inhibitor SB203580 relieved the Cory-induced inhibition on cell growth. Cory remarkably blocked pancreatic tumour growth in vivo.

CONCLUSIONS

Cory exerts an anti-tumour effect on pancreatic cancer primarily via ROS-p38-mediated cytostatic effects. Cory may serve as a promising therapeutic agent for pancreatic cancer.

Sustained ICP Elevation Is a Driver of Spatial Memory Deficits After Intraventricular Hemorrhage and Leads to Activation of Distinct Microglial Signaling Pathways

The mechanisms of cognitive decline after intraventricular hemorrhage (IVH) in some patients continue to be poorly understood. Multiple rodent models of intraventricular or subarachnoid hemorrhage have only shown mild or even no cognitive impairment on subsequent behavioral testing. In this study, we show that intraventricular hemorrhage only leads to a significant spatial memory deficit in the Morris water maze if it occurs in the setting of an elevated intracranial pressure (ICP). Histopathological analysis of these IVH + ICP animals did not show evidence of neuronal degeneration in the hippocampal formation after 2 weeks but instead showed significant microglial activation measured by lacunarity and fractal dimensions. RNA sequencing of the hippocampus showed distinct enrichment of genes in the IVH + ICP group but not in IVH alone having activated microglial signaling pathways. The most significantly activated signaling pathway was the classical complement pathway, which is used by microglia to remove synapses, followed by activation of the Fc receptor and DAP12 pathways. Thus, our study lays the groundwork for identifying signaling pathways that could be targeted to ameliorate behavioral deficits after IVH.

Profiling Differential Effects of 5 Selective Serotonin Reuptake Inhibitors on TLRs-Dependent and -Independent IL-6 Production in Immune Cells Identifies Fluoxetine as Preferred Anti-Inflammatory Drug Candidate

Excessive proinflammatory cytokine production induced by abnormal activation of Toll-like receptor (TLR) signaling, for example, by SARS-CoV-2 infection, can cause a fatal cytokine storm. The selective serotonin reuptake inhibitors (SSRIs) fluoxetine and fluvoxamine, used to treat depression, were recently reported to reduce the risk of severe disease in patients with coronavirus disease 2019 (COVID-19), but the mechanisms of the anti-inflammatory effects of SSRIs, and which SSRI would be most suitable as an anti-inflammatory drug, remain unclear. Here, we examined the inhibitory effects of 5 FDA-approved SSRIs, paroxetine, fluoxetine, fluvoxamine, sertraline and escitalopram, on the production of interleukin-6 (IL-6) induced by stimulation with multiple TLR agonists in murine macrophages and dendritic cells, and on the production of cytokines induced by concanavalin A in murine lymphocytes. In J774.1 murine macrophage cells, pretreatment with SSRIs significantly suppressed IL-6 release induced by TLR3 agonist poly(I:C), TLR4 agonist LPS or TLR9 agonist CpG ODN, but did not affect IL-6 release induced by TLR7 agonists imiquimod or resiquimod. In accordance with the results obtained in J774.1 cells, pretreatment with SSRIs also suppressed IL-6 release induced by a TLR3, TLR4 or TLR9 agonist in bone marrow-derived dendritic cells and peritoneal cells of C57BL/6 mice. On the other hand, interestingly, sertraline alone among the SSRIs amplified IL-6 production induced by TLR7 agonists in murine dendritic cells, though not in macrophages. Concanavalin A-induced production of IL-6 or IL-2 in murine lymphocytes was suppressed by SSRIs, suggesting that SSRIs also inhibit TLRs-independent IL-6 production. Since SSRIs suppressed both IL-6 production induced by multiple TLR agonists in macrophages or dendritic cells and TLR-independent IL-6 production in lymphocytes, they are promising candidates for treatment of patients with cytokine storm, which is mediated by overactivation of multiple TLRs in a complex manner, leading to the so-called IL-6 amplifier, an IL-6 overproduction loop. However, the 5 SSRIs examined here all showed different effects. Overall, our results suggest that fluoxetine may be the most promising candidate as an anti-inflammatory drug. An examination of the structural requirements indicated that the N-methyl group of fluoxetine has a critical role in the inhibition of IL-6 production.

The Neuroprotection of Verbascoside in Alzheimer’s Disease Mediated through Mitigation of Neuroinflammation via Blocking NF-κB-p65 Signaling

Verbascoside (VB) is a phenylethanoid glycoside extracted from the herbaceous plant Verbascum sinuatum and plays a neuroprotective role in Alzheimer’s disease (AD). The goal of this study was to explore the neuroprotective mechanism of VB. Based on the proteomics analysis, immunohistochemistry, immunofluorescence, Western blot, and ELISA were utilized to explore the neuroprotective mechanism of VB in context of neuroinflammation in APP/PS1 mice, LPS-induced BV2 cells, and/or Aβ_1-42-stimulated N2a cells. Proteomic analysis demonstrated that the neuroprotection of VB correlated closely to its anti-inflammatory effect. VB significantly blocked microglia and astrocyte against activation in brains of APP/PS1 mice, suppressed the generation of IL-1β as well as IL-6, and boosted that of IL-4, IL-10 and TGF-β in vivo, which were analogous to results acquired in vitro. Furthermore, VB effectively restrained the phosphorylation of IKKα+β, IκBα, and NF-κB-p65 in APP/PS1 mice; LPS-induced BV2 cells, and Aβ_1-42-stimulated N2a cells and lowered the tendency of NF-κB-p65 translocation towards nucleus in vitro. These results demonstrate that the neuroprotective effect of VB correlates to the modulation of neuroinflammation via NF-κB-p65 pathway, making VB as a hopeful candidate drug for the prevention and treatment of AD.

Pharmacological Investigations in Glia Culture Model of Inflammation

Astrocytes and microglia are the main cell population besides neurons in the central nervous system (CNS). Astrocytes support the neuronal network via maintenance of transmitter and ion homeostasis. They are part of the tripartite synapse, composed of pre- and postsynaptic neurons and perisynaptic astrocytic processes as a functional unit. There is an increasing evidence that astroglia are involved in the pathophysiology of CNS disorders such as epilepsy, autoimmune CNS diseases or neuropsychiatric disorders, especially with regard to glia-mediated inflammation. In addition to astrocytes, investigations on microglial cells, the main immune cells of the CNS, offer a whole network approach leading to better understanding of non-neuronal cells and their pathological role in CNS diseases and treatment. An in vitro astrocyte-microglia co-culture model of inflammation was developed by Faustmann et al. (2003), which allows to study the endogenous inflammatory reaction and the cytokine expression under drugs in a differentiated manner. Commonly used antiepileptic drugs (e.g., levetiracetam, valproic acid, carbamazepine, phenytoin, and gabapentin), immunomodulatory drugs (e.g., dexamethasone and interferon-beta), hormones and psychotropic drugs (e.g., venlafaxine) were already investigated, contributing to better understanding mechanisms of actions of CNS drugs and their pro- or anti-inflammatory properties concerning glial cells. Furthermore, the effects of drugs on glial cell viability, proliferation and astrocytic network were demonstrated. The in vitro astrocyte-microglia co-culture model of inflammation proved to be suitable as unique in vitro model for pharmacological investigations on astrocytes and microglia with future potential (e.g., cancer drugs, antidementia drugs, and toxicologic studies).

Clinical Management of COVID-19 in Cancer Patients with the STAT3 Inhibitor Silibinin

COVID-19 pathophysiology is caused by a cascade of respiratory and multiorgan failures arising, at least in part, from the SARS-CoV-2-driven dysregulation of the master transcriptional factor STAT3. Pharmacological correction of STAT3 over-stimulation, which is at the root of acute respiratory distress syndrome (ARDS) and coagulopathy/thrombosis events, should be considered for treatment of severe COVID-19. In this perspective, we first review the current body of knowledge on the role of STAT3 in the pathogenesis of severe COVID-19. We then exemplify the potential clinical value of treating COVID-19 disease with STAT3 inhibitors by presenting the outcomes of two hospitalized patients with active cancer and COVID-19 receiving oral Legalon®-a nutraceutical containing the naturally occurring STAT3 inhibitor silibinin. Both patients, which were recruited to the clinical trial SIL-COVID19 (EudraCT number: 2020-001794-77) had SARS-CoV-2 bilateral interstitial pneumonia and a high COVID-GRAM score, and showed systemic proinflammatory responses in terms of lymphocytopenia and hypoalbuminemia. Both patients were predicted to be at high risk of critical COVID-19 illness in terms of intensive care unit admission, invasive ventilation, or death. In addition to physician's choice of best available therapy or supportive care, patients received 1050 mg/day Legalon® for 10 days without side-effects. Silibinin-treated cancer/COVID-19+ patients required only minimal oxygen support (2-4 L/min) during the episode, exhibited a sharp decline of the STAT3-regulated C-reactive protein, and demonstrated complete resolution of the pulmonary lesions. These findings might inspire future research to advance our knowledge and improve silibinin-based clinical interventions aimed to target STAT3-driven COVID-19 pathophysiology.

Purinergic receptor ligands: the cytokine storm attenuators, potential therapeutic agents for the treatment of COVID-19

The coronavirus disease-19 (COVID-19), at first, was reported in Wuhan, China, and then rapidly became pandemic throughout the world. Cytokine storm syndrome (CSS) in COVID-19 patients is associated with high levels of cytokines and chemokines that cause multiple organ failure, systemic inflammation, and hemodynamic instabilities. Acute respiratory distress syndrome (ARDS), a common complication of COVID-19, is a consequence of cytokine storm. In this regard, several drugs have been being investigated to suppress this inflammatory condition. Purinergic signaling receptors comprising of P1 adenosine and P2 purinoceptors play a critical role in inflammation. Therefore, activation or inhibition of some subtypes of these kinds of receptors is most likely to be beneficial to attenuate cytokine storm. This article summarizes suggested therapeutic drugs with potential anti-inflammatory effects through purinergic receptors.