Barath, Abhijeet S.

The discovery of genes encoding the volume-regulated anion channel (VRAC) has enabled detailed exploration of its cell type–specific roles in the brain. LRRC8A (SWELL1) is the essential VRAC subunit. We observed seizure-induced, subunit-specific changes in microglial VRAC expression and investigated its function using conditional KO (cKO) of LRRC8A in microglia. SWELL1 cKO mice exhibited a male-specific increase in kainate-induced seizure severity, yet showed paradoxical neuroprotection against seizure-associated neuronal loss. Mechanistically, SWELL1 deletion led to a cell-autonomous reduction in microglial density and decreased release of VRAC-permeable neuroactive metabolites, including taurine, GABA, and glutamate in culture. Additionally, impaired phagocytic kinetics and reduced lysosomal biogenesis contributed to the observed neuroprotection. These findings reveal potentially novel roles for microglial VRAC in regulating seizure outcomes and microglia-neuron interactions.

Abstract BACKGROUND Despite multimodal treatment, brain tumors frequently recur and are often life-threatening. Patients commonly experience progressive neurologic decline, significantly impacting quality of life. We aimed to characterize the symptom burden of central nervous system tumors and to explore patient and caregiver experiences. METHODS In this observational study (NCT06676306), we conducted semi-structured interviews with 22 patients receiving care through the Mayo Clinic Neuro-oncology division. Caregivers were invited to participate. Demographic data were obtained from electronic medical records. Interviews were recorded, transcribed, and analyzed thematically. RESULTS Twenty-two patients (9/22, 41% female; median age 41.5 years, range 24–71) and 13 caregivers (13/22, 59%) participated. Diagnoses included astrocytoma, IDH mutant (8/22, 36%), glioblastoma (4/22, 18%), oligodendroglioma (3/22, 14%), astrocytoma, IDH wildtype (2/22, 9%), and other (5/22, 23%). The most frequently reported symptoms were headaches (13/22, 59%), cognitive changes (8/22, 36%), and fatigue (7/22, 32%). Among twenty patients who discussed treatment impacts, the most common were fatigue (45%), cognitive changes (40%), and mood changes (40%). Caregivers reported emotional toll (13/13, 100%), career changes (7/13, 54%), and difficulty balancing responsibilities (6/13, 46%). Twenty-one patients shared coping strategies, including faith (29%), hobbies (24%), and exercise (19%). All 20 respondents who discussed overall experience with neuro-oncology care reported a positive overall experience (100%), with the patient–neuro-oncologist relationship (40%) and communication (39%) cited as key contributors. For 19 patients who discussed treatment outcomes, quality of life (26%), maintaining function (21%), and tumor stability (21%) were paramount. For 9 caregivers who discussed treatment outcomes, 44% prioritized quality of life and 44% reported desire for a cure. CONCLUSIONS Brain tumors and their treatments affect patients and caregivers across physical, emotional, and social domains. Strong relationships and communication with the care team are central to patient satisfaction. Quality of life should be prioritized in neuro-oncology research and trials.

Abstract Microglia are resident immune cells critical in maintaining brain homeostasis via their surveillance and phagocytosis function. Under disease contexts such as seizures and epilepsy, microglial phagocytic signalling is activated in response to both inflammatory and non‐inflammatory cell death. This process involves a range of well‐characterized ‘find me’ and ‘eat me’ signals, phagocytic receptors, and less well‐characterized intracellular signalling pathways. In addition, epigenetic and transcriptional regulators orchestrate microglial responses to seizures, including the integration of phagocytic and inflammatory pathways. Interestingly, although inhibiting phagocytosis has been shown to improve neuronal survival and cognitive performance after seizures, it paradoxically increases the risk of developing spontaneous recurrent seizures. Reconciling these dual effects requires a deeper understanding the spatiotemporal dynamics of microglial phagocytosis. The objective of this review is to examine the mechanisms and impact of microglial phagocytosis in the context of epilepsy and to highlight unresolved questions that warrant further investigation in this emerging field. image

Abstract Understanding the function of non-coding genomic sequence variants represents a challenge for biomedicine. Many diseases are products of gene-by-environment interactions with complex mechanisms. This study addresses these themes by mechanistic characterization of non-coding variants that influence gene expression only after drug or hormone exposure. Using glucocorticoid signaling as a model system, we integrated genomic, transcriptomic, and epigenomic approaches to unravel mechanisms by which variant function could be revealed by hormones or drugs. Specifically, we identified cis-regulatory elements and 3D interactions underlying ligand-dependent associations between variants and gene expression. One-quarter of the glucocorticoid-modulated variants that we identified had already been associated with clinical phenotypes. However, their affected genes were ‘unmasked’ only after glucocorticoid exposure and often with function relevant to the disease phenotypes. These diseases involved glucocorticoids as risk factors or therapeutic agents and included autoimmunity, metabolic and mood disorders, osteoporosis and cancer. For example, we identified a novel breast cancer risk gene, MAST4, with expression that was repressed by glucocorticoids in cells carrying the risk genotype, repression that correlated with MAST4 expression in breast cancer and treatment outcomes. These observations provide a mechanistic framework for understanding non-coding genetic variant-chemical environment interactions and their role in disease risk and drug response.

Abstract Neurochemical recording techniques have expanded our understanding of the pathophysiology of neurological disorders, as well as the mechanisms of action of treatment modalities like deep brain stimulation (DBS). DBS is used to treat diseases such as Parkinson’s disease, Tourette syndrome, and obsessive-compulsive disorder, among others. Although DBS is effective at alleviating symptoms related to these diseases and improving the quality of life of these patients, the mechanism of action of DBS is currently not fully understood. A leading hypothesis is that DBS modulates the electrical field potential by modifying neuronal firing frequencies to non-pathological rates thus providing therapeutic relief. To address this gap in knowledge, recent advances in electrochemical sensing techniques have given insight into the importance of neurotransmitters, such as dopamine, serotonin, glutamate, and adenosine, in disease pathophysiology. These studies have also highlighted their potential use in tandem with electrophysiology to serve as biomarkers in disease diagnosis and progression monitoring, as well as characterize response to treatment. Here, we provide an overview of disease-relevant neurotransmitters and their roles and implications as biomarkers, as well as innovations to the biosensors used to record these biomarkers. Furthermore, we discuss currently available neurochemical and electrophysiological recording devices, and discuss their viability to be implemented into the development of a closed-loop DBS system.

The development of closed-loop deep brain stimulation (DBS) systems represents a significant opportunity for innovation in the clinical application of neurostimulation therapies. Despite the highly dynamic nature of neurological diseases, open-loop DBS applications are incapable of modifying parameters in real time to react to fluctuations in disease states. Thus, current practice for the designation of stimulation parameters, such as duration, amplitude, and pulse frequency, is an algorithmic process. Ideal stimulation parameters are highly individualized and must reflect both the specific disease presentation and the unique pathophysiology presented by the individual. Stimulation parameters currently require a lengthy trial-and-error process to achieve the maximal therapeutic effect and can only be modified during clinical visits. The major impediment to the development of automated, adaptive closed-loop systems involves the selection of highly specific disease-related biomarkers to provide feedback for the stimulation platform. This review explores the disease relevance of neurochemical and electrophysiological biomarkers for the development of closed-loop neurostimulation technologies. Electrophysiological biomarkers, such as local field potentials, have been used to monitor disease states. Real-time measurement of neurochemical substances may be similarly useful for disease characterization. Thus, the introduction of measurable neurochemical analytes has significantly expanded biomarker options for feedback-sensitive neuromodulation systems. The potential use of biomarker monitoring to advance neurostimulation approaches for treatment of Parkinson’s disease, essential tremor, epilepsy, Tourette syndrome, obsessive-compulsive disorder, chronic pain, and depression is examined. Further, challenges and advances in the development of closed-loop neurostimulation technology are reviewed, as well as opportunities for next-generation closed-loop platforms.

The comprehensive microscopic, spectroscopic, and in vitro voltammetric analysis presented in this work, which builds on the well-studied properties of carbon-based materials, facilitates potential ways for improvement of carbon fiber microelectrodes (CFMs) for neuroscience applications. Investigations by both, scanning electron microscopy (SEM) and confocal Raman spectroscopy, confirm a higher degree of structural ordering for the fibers exposed to carbonization temperatures. An evident correlation is also identified between the extent of structural defects observed from SEM and Raman results with the CFM electrochemical performance for dopamine detection. To improve CFM physico-chemical surface stability and increase its mechanical resistance to the induced compressive stress during anticipated in vivo tissue penetration, successful coating of the carbon fiber with boron-doped diamond (BDD) is also performed and microspectroscopically analyzed here. The absence of spectral shifts of the diamond Raman vibrational signature verifies that the growth of an unstrained BDD thin film was achieved. Although more work needs to be done to identify optimal parameter values for improved BDD deposition, this study serves as a demonstration of foundational technology for the development of more sensitive electrochemical sensors, that may have been impractical previously for clinical applications, due to limitations in either safety or performance.