Biology subjects

Moshkforoush, A.

Publications and source records attributed to Moshkforoush, A..

4 recordsLinked to original sources

bioRxiv2025

Dual targeting of transferrin receptor and CD98hc enhances brain exposure of large molecules

Targeting proteins highly expressed at the blood-brain barrier, including transferrin receptor (TfR) and CD98hc, is a transformative approach enabling more effective brain delivery of biotherapeutics for treatment of neurological diseases. TfR-mediated delivery promotes rapid, high brain uptake, while CD98hc-mediated delivery is slower with more prolonged exposure. Here, we engineer a huIgG Fc domain to bind both TfR and CD98hc to create a dual transport vehicle (TV) platform that drives distinct brain delivery properties. Dual TVs achieve significantly higher brain concentrations than TVs targeting either TfR or CD98hc alone. Modulation of TfR and CD98hc affinities shifts dual TV brain exposure kinetics and biodistribution. Stronger TfR affinity drives faster brain uptake and clearance, while stronger CD98hc affinity yields higher, more sustained concentrations, likely due to CD98hc affinity-dependent reduction in TfR-mediated neuronal internalization. This dual targeting strategy leverages the complementary properties of TfR and CD98hc-mediated brain exposure to increase optionality for brain delivery of biotherapeutics.

neuroscience↗

bioRxiv2024

Fc-engineered large molecules targeting blood-brain barrier transferrin receptor and CD98hc have distinct central nervous system and peripheral biodistribution compared to standard antibodies

The blood-brain barrier (BBB) poses a significant challenge drug delivery to the brain. BBB-crossing molecules are emerging as a new class of therapeutics with significant potential for central nervous system (CNS) indications. In particular, transferrin receptor (TfR)- and CD98 heavy chain (CD98hc)-targeting molecules have been demonstrated to cross the BBB for enhanced brain delivery. Previously, we reported TfR and CD98hc antibody transport vehicles (ATVTfR and ATVCD98hc) that utilize these BBB receptors to improve CNS drug delivery1,2. Here, we provide a comprehensive and unbiased biodistribution characterization of ATVTfR and ATVCD98hc compared to a standard IgG at a multiscale level, ranging from whole-body to brain region- and cell type-targeting specificity. Mouse whole-body tissue clearing revealed distinct organ localization for each molecule. In the CNS, ATVTfR and ATVCD98hc not only achieves enhanced brain delivery but importantly, much broader parenchymal distribution in contrast to the severely limited distribution observed with a standard antibody that was not able to be improved even at very high dose levels. Using cell sorting and single-cell RNA sequencing of mouse brain, we revealed that standard IgG predominantly localizes to perivascular and leptomeningeal cells and reaches the CNS by entering the CSF, rather than crossing the BBB. In contrast, ATVTfR and ATVCD98hc enables broad parenchymal cell-specific distribution via transcytosis through brain endothelial cells (BECs) along the neurovasculature. Finally, we extended the translational relevance of our findings by revealing enhanced and broad brain and spinal cord biodistribution of ATVTfR compared to standard IgG in cynomolgus monkey. Taken together, this multiscale analysis reveals in-depth biodistribution differences between ATVTfR, ATVCD98hc, and standard IgG. These results may better inform platform selection for specific therapeutic targets of interest, optimally matching platforms to desired CNS target engagement, peripheral organ exposures, and predict or potentially reduce off-target effects.

neuroscience↗

bioRxiv2019

Unraveling ChR2-driven stochastic Ca2+ dynamics in astrocytes - A call for new interventional paradigms

Control of astrocytes via modulation of Ca2+ oscillations using techniques like optogenetics can prove to be crucial in therapeutic intervention of a variety of neurological disorders. However, a systematic study quantifying the effect of optogenetic stimulation in astrocytes is yet to be performed. Here, we propose a novel stochastic Ca2+dynamics model that incorporates the light sensitive component - channelrhodopsin 2 (ChR2). Utilizing this model, we studied the effect of various pulsed light stimulation paradigms on astrocytes for select variants of ChR2 (wild type, ChETA, and ChRET/TC) in both an individual and a network of cells. Our results exhibited a consistent pattern of Ca2+ activity among individual cells in response to optogenetic stimulation, i.e., showing steady state regimes with increased Ca2+ basal level and Ca2+ spiking probability. Furthermore, we performed a global sensitivity analysis to assess the effect of stochasticity and variation of model parameters on astrocytic Ca2+ dynamics in the presence and absence of light stimulation, respectively. Results indicated that directing variants towards the first open state of the photo-cycle of ChR2 (o1) enhances spiking activity in astrocytes during optical stimulation. Evaluation of the effect of astrocytic ChR2 expression (heterogeneity) on Ca2+ signaling revealed that the optimal stimulation paradigm of a network does not necessarily coincide with that of an individual cell. Simulation for ChETA-incorporated astrocytes suggest that maximal activity of a single cell reduced the spiking probability of the network of astrocytes at higher degrees of ChR2 expression efficiency due to an elevation of basal Ca2+ beyond physiological levels. Collectively, the framework presented in this study provides valuable information for the selection of light stimulation paradigms that elicit optimal astrocytic activity using existing ChR2 constructs, as well as aids in the engineering of future optogenetic constructs. Author summaryOptogenetics - an avant-garde technique involves targeted delivery of light sensitive ion channels to cells. Channelrhodopsin 2 (ChR2), an algal derived light sensitive ion channel has extensively been used in neuroscience to manipulate various cell types in a guided and controlled manner. Despite being predominantly used in neurons, recent advancements have led to the expansion of the application of optogenetics in non-neuronal cell types, like astrocytes. These cells play a key role in various aspects of the central nervous system and alteration of their signaling is associated with various disorders, including epilepsy, stroke and Alzheimers disease. Hence, invaluable information for therapeutic intervention can be obtained from using optogenetics to regulate astrocytic activity in a strategic manner. Here, we propose a novel computational model to assess astrocytic response to optogenetic stimulation which implicitly accounts for the stochastic character of Ca2+ signaling in this cell type. We identified light stimulation paradigms suitable for eliciting astrocytic Ca2+ response within physiological levels in widely-used ChR2 variants and identified highly sensitive parameters in ChR2 kinetics conducive for higher probability in Ca2+ spiking. Overall, the results of this model can be used to boost astrocyte light-induced behavior prediction and the development of improved future optogenetic constructs.

neuroscience↗

bioRxiv2018

Identification negative BOLD responses using windkessel models

Alongside positive BOLD responses (PBR), a variety of negative BOLD responses (NBR) with distinct underlying mechanisms also occur. We identify five mechanisms of NBR: i) local/lateral/contralateral inhibition (LCI), ii) neuronal disruption of network activity (NDA), iii) altered balance of neuro-metabolic/vascular couplings (ANC), iv) arterial blood stealing (ABS), and v) venous blood backpressure (VBB). Detecting and classifying these mechanisms from BOLD signals is pivotal in understanding normal/pathological brain functions. This requires models and parameters with anatomical/functional interpretation that furnish the understanding of how these mechanisms are fingerprinted by their BOLD responses. Here, we used a windkessel model with viscoelastic compliance as well as dynamics of both neuronal and tissue/blood O2 to investigate the generation, detection, classification and interpretation of the BOLD hemodynamic response functions (HRF) of above mechanisms. Firstly, we evaluated the use of the general linear model to detect simulated NBRs. Secondly, we tested the ability of a machine learning classifier, built from a simulated ensemble of HRFs, to predict the mechanism underlying a new HRF. Crossvalidation indicates NDA and ANC can accurately be classified solely from fMRI BOLD signals; while LCI, ABS and VBB might require additional imaging modalities. Thirdly, we demonstrated that estimators of the model parameters determinant in the NBRs formation are accurate, and precise to certain resolutions. Finally, we successfully applied our detection/classification/estimation methodology to EEG-fMRI data in a clinical situation where several of these mechanisms could coexist. We believe that the proper identification and interpretation of NBR mechanisms have important clinical and cognitive implications in fMRI studies.

neuroscience↗