European Brain Research Institute

Epilepsy is a prevalent neurological disorder characterized by recurrent, unprovoked seizures and altered electroencephalographic patterns. This condition is viewed as a malfunctioning of extensive neural networks due to an imbalance of excitatory and inhibitory signals leading neurons to be excessively excitable and to abnormal synchronized electrical activity. Despite the growing number of new antiepileptic drugs, patients suffering from drug-resistant forms of epilepsy do not respond to pharmacological treatment, and the only effective cure remains the neurosurgical resection of the epileptic focus. Nevertheless, several patients fail to achieve seizure freedom after surgical resection. This emphasizes the urgent need for novel human-relevant models to explore the mechanisms underlying drug-refractory forms of epilepsy. While acute and organotypic slices from resected neurological tissue offer a promising method for studying patient-derived brain tissue mechanisms, this technique is limited by its inherently low throughput and challenges in obtaining appropriate control tissue. Recent advances in organoid technology have allowed for the generation of cerebral dorsal/ventral assembloids, which more accurately model the functional connectivity between excitatory and inhibitory neurons and recapitulate key aspects of cortical circuits. This review summarizes current knowledge on the use of human brain organoids and assembloids to model epilepsy, with a particular focus on organoids harboring focal cortical dysplasia-linked mutations. Human brain organoids and assembloids will allow addressing an important question in the field, namely the relative contribution of neurodevelopmental defects vs. those arising at later stages of CNS development. Limitations of this “neuron-only” in vitro model and potential ways to include non-neuronal cells will also be discussed. Finally, we highlight recent advances in employing these new powerful platforms for investigating network dysfunctions underlying FCDs, screening potential antiepileptic drug candidates, and developing personalized therapeutic strategies.

Brain microRNAs (miRs) are expressed in a cell-specific manner and are implicated in several pathologies. Despite circulating miRs (c-miRs) being increasingly recognized as biomarkers of brain disorders, few studies have directly linked specific brain regions or cell types to plasma miR levels under physiological conditions. In the dorsal raphe nuclei (DRN), mir-34a is selectively expressed in GABAergic neurons. This expression increases following prolonged stimuli that challenge DRN activity, like repeated stress or chronic SSRI administration. Here, we investigate whether plasma levels of miR-34a can serve as peripheral indicators of its expression in the DRN. In mice exposed to repeated social defeat stress or chronic SSRIs administration, we observed a significant increase in plasma miR-34a levels, suggesting that DRN homeostatic changes are reflected in c-miR profiles. To identify the source of plasma miR-34a, we employed a genetic approach enabling selective deletion of miR-34a in GABAergic neurons. This resulted in a marked reduction of miR-34a in both DRN and plasma, but not in other brain regions, demonstrating that DRN GABAergic neurons are the main contributors to c-miR-34a. Complementarily, intra-DRN infusion of AntagomiR-34a reproduced the reduction in plasma miR-34a, confirming the DRN as a key anatomical source. Strikingly, the same infusion reduced miR-34a expression in ependymal cells of the choroid plexus, suggesting a potential route of miR-34a from brain to periphery. These findings establish that plasma miR-34a reflects miR-34a expression in DRN GABAergic neurons and demonstrate that c-miRs can report homeostatic adaptations of a defined neuronal population within a specific brain region.

Spaceflight missions represent a new exposome, unpredicted by evolution. Life-threatening agents activate non-specific stress responses involving the psycho-immune-neuroendocrine network. The main molecular pathways regulating this network and those affected by spaceflight exposome/microgravity are reported in various experimental setups. They include gut microbiota-derived metabolites, potentially valuable for countermeasure development. Meaningfully, the application of neuromodulation techniques, like the non-invasive transcutaneous vagal stimulation, for the prevention of pathophysiological alterations related to stress responses, is discussed.

Background: the Skill, Rule, and Knowledge (S-R-K) model is a framework used to describe and analyze human behaviour and decision-making in complex environments based on the nature of the task and kind of cognitive control required. The S-R-K model is particularly useful in fields like human factor engineering, system design, and safety-critical industries because it helps to understand human errors and how they relate to different levels of cognitive control. However, the S-R-K model is still qualitative and lacks specific and quantifiable metrics for determining what kind of cognitive control a person is using at any given time. This aspect makes difficult to directly measure and compare performance across the three levels. This study aimed therefore to characterize the S-R-K model from a neurophysiological perspective by analyzing the operator’s cerebral cortical activity. Methods: in this study, participants carried out experimental tasks able to replicate the Skill (tracking task), Rule (rule-based navigation) and Knowledge conditions (unfamiliar situations). Results: participants’ Electroencephalogram (EEG) was recorded during tasks execution and then Global Field Power (GFP) was estimated in the different EEG frequency bands. Brodmann areas (BAs) and EEG features were then used to characterize the S-R-K pattern over the cerebral cortex and as inputs to build up the machine learning-based model to estimate participants’ cognitive control behaviours while dealing with tasks. Conclusions: the results demonstrate the possibility of objectively measuring the different S, R and K levels in terms of brain activations. Furthermore, such evidence is consistent with the scientific literature in terms of cognitive functions corresponding to the different levels of cognitive control.

Growing evidence suggests that Reelin signals and cleavages are affected in neurodegenerative diseases, prospecting a potential role for Reelin in the pathogenesis of neurodegenerative processes occurring in insulted retinas. We sought to determine whether Reelin, Aβ1-42, FTH1 and TAU proteins accumulate in ocular fluids of idiopathic epiretinal membrane (iERM) specimens and whether such accumulations depend on disease severity. Comparisons and correlation studies were used to verify the hypothesis of a Reelin, Aβ1-42, TAU and FTH1 marker expressions in this vitreoretinal disease, extending the knowledge on the pathological spectrum of neurodegenerative eye diseases. Aqueous, vitreous and peeled-off ERM samples were collected from patients who had undergone vitrectomy and grouped according to disease severity. We found out that Reelin and Aβ1-42 were expressed in ocular fluids and affected ERMs depending on disease severity. At stage 3, higher Reelin and Aβ1-42 immunofluorescence staining was detected in ERMs, in agreement with the higher Reelin, Aβ1-42, FTH1 and TAU transcript expressions by RT-PCR. Differential expressions of transcripts specific to Aβ1-42, FTH1, GFAP and TAU occurred in vitreal hyalocytes and astrocytes, which selectively responded to vitreal exposure. This is the first study reporting the association between Reelin and ERM disease, highlighting the potential role of Reelin in neurodegenerating and Drusen-affected retinas. The potential association of neurodegenerative mediators with ERM would suggest that part of the neuronal damage activated at the vitreoretinal interphase might be driven by Reelin.

Vitamin K is essential for many physiological processes, including coagulation, bone metabolism, tissue calcification, and antioxidant activity. Vitamin K vitamers are represented by lipophilic compounds with similar chemical structure (i.e., phylloquinone (vitamin K1) and menaquinone (vitamin K2)). Vitamin K deficiency can affect coagulation and vascular calcification, increasing the risk of hemorrhages, atherosclerosis, cerebrovascular diseases, and neurodegeneration. Recently, several studies have hypothesized a possible dual role of vitamin K vitamers in benefiting both vascular and cerebral health, e.g., by sphingolipids biosynthesis or ferroptosis inhibition. The aim of this narrative review is to deepen the understanding of biological activities of vitamin K and its possible dual protective/preventive actions in neurovascular and degenerative conditions, e.g., stroke and dementia. Given the difficulties related to hemorrhagic risk entailed in the prevention of strokes, the function of vitamin K antagonists is also investigated. Finally, we track the development of a clinical concept for a future preventive strategy and innovative use of vitamin K as a supplement to counteract neurovascular and pathological processes, focusing in particular on stroke and dementia.

Cannabinol (CBN) is a secondary metabolite of cannabis whose beneficial activity on inflammatory diseases of human skin has attracted increasing attention. Here, we sought to investigate the possible modulation by CBN of the major elements of the endocannabinoid system (ECS), in both normal and lipopolysaccharide-inflamed human keratinocytes (HaCaT cells). CBN was found to increase the expression of cannabinoid receptor 1 (CB1) at gene level and that of vanilloid receptor 1 (TRPV1) at protein level, as well as their functional activity. In addition, CBN modulated the metabolism of anandamide (AEA) and 2-arachidonoylglicerol (2-AG), by increasing the activities of N-acyl phosphatidylethanolamines-specific phospholipase D (NAPE-PLD) and fatty acid amide hydrolase (FAAH)-the biosynthetic and degradative enzyme of AEA-and that of monoacylglycerol lipase (MAGL), the hydrolytic enzyme of 2-AG. CBN also affected keratinocyte inflammation by reducing the release of pro-inflammatory interleukin (IL)-8, IL-12, and IL-31 and increasing the release of anti-inflammatory IL-10. Of note, the release of IL-31 was mediated by TRPV1. Finally, the mitogen-activated protein kinases (MAPK) signaling pathway was investigated in inflamed keratinocytes, demonstrating a specific modulation of glycogen synthase kinase 3β (GSK3β) upon treatment with CBN, in the presence or not of distinct ECS-directed drugs. Overall, these results demonstrate that CBN modulates distinct ECS elements and exerts anti-inflammatory effects-remarkably via TRPV1-in human keratinocytes, thus holding potential for both therapeutic and cosmetic purposes.