Biology subjects

Park, L.

Publications and source records attributed to Park, L..

9 recordsLinked to original sources

bioRxiv2026

A Rationally Designed Transgene Drives CAR T Functional Persistence and Durable Regression of Solid Tumors

The eradication of solid tumors by chimeric antigen receptor (CAR) T cells requires dynamic therapies capable of outlasting an immune suppressive tumor microenvironment (TME). However, biological barriers--including rapid exhaustion, poor expansion, and loss of stem-like memory--quickly neutralize these therapies. Because single-technology interventions often introduce unacceptable tradeoffs between efficacy and safety, durable remission demands a paradigm where multiple engineered solutions work in concert. To holistically address these mechanisms, we rationally designed a single-vector transgene that intrinsically drives CAR T functional persistence. The platform integrates four synergistic technologies: a high-avidity mesothelin (MSLN)-targeting CAR optimized to resist shed decoy antigens, a T-cell activation-responsive promoter (OUTLAST OP1) resisting exhaustion, a CD8-targeted designed IL-2 cytokine (OUTSMART dIL-2) driving intratumoral CAR-T expansion, and an EGFRopt safety switch. In lung and ovarian cancer models, this rational integration was required to drive antigen-dependent T cell expansion and eradicate established tumors at extremely low CAR T doses. Furthermore, engineered cells established a self-renewing pool of stem-like memory T cells capable of rejecting tumor rechallenge months later. Ultimately, this work demonstrates that intrinsic T cell dysfunction and extrinsic tumor-derived barriers can be simultaneously overcome by integrating synergistic technologies.

synthetic biology↗

bioRxiv2025

Fifteen-year microbiome survey of endangered killer whales (Orcinus orca) reveals declining diversity and population differences

The endangered Southern Resident killer whale (Orcinus orca) (SRKW) population is burdened by multiple anthropogenic stressors with limited non-invasive approaches for health surveillance. The gut microbiome is interconnected with host physiology and can be characterized using remotely collected fecal samples, creating unique opportunities to integrate environmental and individualized host-associated features of health. In this study, we used fecal samples collected over a 15-year period (2005-2019) from 77% of the living, wild SRKW population (56 individuals, 1-17 time points per individual), as well as fecal samples from the conspecific Northern and Alaska Resident killer whale populations, to characterize distal gut microbiota structure and genomic composition. SRKW microbiotas were individualized and distinct from those of the nearby Northern and Alaska Resident populations, both of which exhibit consistently higher fecundity and survivorship. During the study period, SRKW fecal microbiota species richness declined, despite stability over periods of time less than or equal to 1 year. Several potential bacterial pathogens, such as Fusobacterium spp., achieved dominance in the fecal microbiotas of SRKW individuals sampled within 6 months of death. These findings demonstrate the feasibility and value of harnessing non-invasively collected fecal samples and microbiome profiles for longitudinal killer whale health surveillance.

microbiology↗

bioRxiv2025

The inner membrane complex protein, IMC55, is dispensable for intra-erythrocytic development of Plasmodium falciparum

Plasmodium falciparum, an obligate intracellular Apicomplexan parasite and the causative agent of malaria must reside and replicate within a host cell during the intra-erythrocytic stage. The parasite utilizes a specialized double-membraned organelle, called the inner membrane complex for schizont-stage segmentation and merozoite motility during subsequent re-invasion. In this study, we investigate the function of IMC55, a multi-transmembrane inner membrane complex protein, which we identified as a putative interacting partner of the P. falciparum ER-resident calcium binding protein, PfERC. We have previously shown that PfERC is essential for parasite egress and our data shows that PfERC may also function in parasite invasion into the RBC. The whole genome transposon mutagenesis screen predicts that IMC55 is essential for the intra-erythrocytic asexual cycle. In this work, we show that IMC55 is not required for asexual replication. Following inducible expression of this gene using two conditional systems, we find there is no defect in replicative fitness during the asexual blood stage. Taken together, these data demonstrate that the function of IMC55 is either dispensable or redundant for the Plasmodium falciparum asexual blood stage.

cell biology↗

bioRxiv2025

Perimenopause promotes neuroinflammation in select hippocampal regions in a mouse model of Alzheimers disease

Alzheimers disease (AD) is the most common neurodegenerative disorder characterized by age-dependent amyloid beta (A{beta}) aggregation and accumulation, neuroinflammation, and cognitive deficits. Significantly, there are prominent sex differences in the risk, onset, progression, and severity of AD, as well as response to therapies, with disease burden disproportionately affecting women. Although menopause onset (i.e., perimenopause) may be a critical transition stage for AD susceptibility in women, the role of early ovarian decline in initial disease pathology, particularly key neuroinflammatory processes, is not well understood. To study this, we developed a unique mouse model of perimenopausal AD by combining an accelerated ovarian failure (AOF) model of menopause induced by 4-vinylcyclohexene diepoxide (VCD) with the 5xFAD transgenic AD mouse model. To target early stages of disease progression, 5xFAD females were studied at a young age ([~]4 months) and at the beginning stage of ovarian failure analogous to human perimenopause (termed "peri-AOF"), and compared to age-matched males. Assessment of neuropathology was performed by immunohistochemical labeling of A{beta} as well as markers of astrocyte and microglia activity in the hippocampus, a brain region involved in learning and memory that is deleteriously impacted during AD. Our results show that genotype, AOF, and sex contributed to AD-like pathology. Aggregation of A{beta} was heightened in female 5xFAD mice and further increased at peri-AOF, with hippocampal subregion specificity. Further, select increases in glial activation also paralleled A{beta} pathology in distinct hippocampal subregions. However, cognitive function was not affected by peri-AOF. These findings align with the hypothesis that perimenopause constitutes a period of susceptibility for AD pathogenesis in women.

neuroscience↗

bioRxiv2025

Endothelial-leukocyte interaction in CAR T cell neurotoxicity

CAR-T cells treat cancer, but also cause systemic cytokine release and immune effector cell associated neurotoxicity syndrome (ICANS). In an immunocompetent mouse model, we show by in vivo two-photon imaging that CD19-CAR T treatment causes brain capillary plugging by circulating CAR-T cells and other CD45+ leukocytes, as well as cortical hypoxia. This is accompanied by increased endothelial ICAM-1 and VCAM-1 expression in the brain capillary-venule transition zone, where most of the capillary stalls occur. In the mouse model, circulating CAR-T cells strongly upregulate integrin 4{beta}1 affinity to VCAM-1, but not affinity of integrin L{beta}2 to ICAM-1. Blockade of integrin 4 but not integrin L improves locomotion behavior. In vitro, human brain microendothelial cells upregulate ICAM-1 more than VCAM-1 in response to TNF, IFN-{gamma}, and IL-1{beta}. In a 3D brain human microvessel model, treatment with TNF and IFN-{gamma} is sufficient to induce adhesion of CAR T cells under flow conditions, which is blocked synergistically by antibodies against integrins 4 and L. Finally, patients with the highest levels of TNF and IFN-{gamma} also have the highest blood levels of soluble ICAM-1 and VCAM-1, which in turn correlate with ICANS. Integrin 4 but not L increases in CAR-T cells after they are infused into patients. Combined data from patients, mouse models and in vitro microvessels indicate differential regulation of interactions of ICAM-1 and VCAM-1 with their respective leukocyte integrins. Overall, our study supports the hypothesis that cytokine-driven upregulation of endothelial-leukocyte adhesion is sufficient to induce acute, reversible neurotoxicity. One Sentence SummaryDuring CAR T cell therapy, cytokine release induces white blood cell stalling in brain capillaries by upregulating ICAM-1/VCAM-1-integrin interactions.

immunology↗

bioRxiv2024

45-Color Full Spectrum Flow Cytometry Panel for Deep Immunophenotyping of the Major Lineages Present in Human Peripheral Blood Mononuclear Cells with Emphasis on the T cell Memory Compartment.

The need for more in-depth exploration of the human immune system has moved the flow cytometry field forward with advances in instrumentation, reagent development and user-friendly implementations of data analysis methods. The increase in the number of markers evaluated simultaneously requires a careful selection of highly overlapping dyes to avoid introducing detrimental spread and compromising population resolution. In this manuscript, we present the strategy used in the development of a high-quality human 45-color panel which allows for comprehensive characterization of major cell lineages present in circulation including T cells, gamma delta T cells, NKT-like cells, B cells, NK cells, monocytes, basophils, dendritic cells, and ILCs, as well as more in-depth characterization of memory T cells. The steps taken to ensure that each marker in the panel was optimally resolved are discussed in detail. We highlight the outstanding discernment of cell activation, exhaustion, memory, and differentiation states of CD4+ and CD8+ T cells using this 45-color panel, enabling an in-depth description of very distinct phenotypes associated with the complexity of the T cell memory response. Furthermore, we present how this panel can be effectively used for cell sorting on instruments with a similar optical layout to achieve the same level of resolution. Functional evaluation of sorted specific rare cell subsets demonstrated significantly different patterns of immunological responses to stimulation, supporting functional and phenotypic differences within the T cell memory subsets. In summary, the combination of flow cytometry full spectrum technology, careful assay design and optimization, results in high resolution multiparametric assays. This approach offers the opportunity to fully characterize immunological profiles present in peripheral blood in the context of infectious diseases, autoimmunity, neurodegeneration, immunotherapy, and biomarker discovery. PURPOSE AND APPROPRIATE SAMPLE TYPESThis 45-color flow cytometry-based panel was developed as an expansion of the previously published OMIP-069 [1] and serves as an in-depth immunophenotyping of the major cell subsets present in human peripheral blood. The goal of this panel is to maximize the amount of high-quality data that can be acquired from a single sample, not only for more in-depth characterization of the immune system, but also to address the issue of limited sample availability. The panels development included identifying fluorochromes that could improve the performance of the original 40-color panel and expanding the number of markers for deeper delineation of memory status of T cell subpopulations. To increase the number of markers, it was critical that any expansion did not negatively impact the resolution and quality of the data. To achieve this, the fluorochrome combinations were carefully characterized to ensure optimal resolution of each marker. The panel allows for deep characterization of the major cell lineages present in circulation (CD4 T cells, CDS T cells, regulatory T cells, yo T cells, NKT-like cells, B cells, NK (Natural Killer) cells, monocytes, and dendritic cells), while also providing an in-depth characterization of the T cell compartment, with a combination of activation, inhibitory, exhaustion, and differentiation markers. The panel supports deep exploration of the memory status of CD4+ T cells, CDS+ T cells, and NKT-like cells. The steps taken in the optimization of the panel ensured outstanding resolution of each marker within the multicolor panel and unequivocal identification of each cell subset. This panel design and optimization will enhance the ability to characterize immunological profiles present in peripheral blood in the context of oncology, infectious diseases, autoimmunity, neurodegeneration, immunotherapy, and biomarker discovery. The panel was developed using fresh and cryopreserved human peripheral blood mononuclear cells (PBMCs) from healthy adults. We have not tested the panel on whole blood or biopsies; hence it is anticipated that the panel might require further optimization to be used with other sample types.

immunology↗

bioRxiv2023

Vascular oxidative stress causes neutrophil arrest in brain capillaries, leading to decreased cerebral blood flow and contributing to memory impairment in a mouse model of Alzheimer's disease

INTRODUCTIONIn this study, we explore the role of oxidative stress produced by NOX2-containing NADPH oxidase as a molecular mechanism causing capillary stalling and cerebral blood flow deficits in the APP/PS1 mouse model of AD. METHODSWe inhibited NOX2 in APP/PS1 mice by administering a 10 mg/kg dose of the peptide inhibitor gp91-ds-tat i.p., for two weeks. We used in vivo two-photon imaging to measure capillary stalling, penetrating arteriole flow, and vascular inflammation. We also characterized short-term memory function and gene expression changes in cerebral microvessels. RESULTSWe found that after NOX2 inhibition capillary stalling, as well as parenchymal and vascular inflammation, were significantly reduced. In addition, we found a significant increase in penetrating arteriole flow, followed by an improvement in short-term memory, and downregulation of inflammatory gene expression pathways. DISCUSSIONOxidative stress is a major mechanism leading to microvascular dysfunction in AD, and represents an important therapeutic target.

neuroscience↗

bioRxiv2022

Reactivation of memory-encoding dentate gyrus neurons during memory consolidation is associated with subregion-specific, learning- and sleep-mediated biosynthetic changes

Post-learning sleep is essential for hippocampal memory processing, including contextual fear memory (CFM) consolidation. We used targeted recombination in activated populations (TRAP) to label context-encoding engram neurons in the hippocampal dentate gyrus (DG) and assessed reactivation of these neurons after fear learning. Post-learning sleep deprivation (SD), which impairs CFM consolidation, selectively disrupted reactivation of inferior blade DG engram neurons. This change was linked to more general suppression of neuronal activity markers in the inferior, but not superior, DG blade by SD. To further characterize how learning and subsequent sleep or SD affect these (and other) hippocampal subregions, we used subregion-specific spatial profiling of transcripts and proteins. We found that transcriptomic responses to sleep loss differed greatly between hippocampal regions CA1, CA3, and DG inferior blade, superior blade, and hilus - with activity-driven transcripts, and those associated with cytoskeletal remodeling, selectively suppressed in the inferior blade. Critically, learning-driven transcriptomic changes, measured 6 h following contextual fear learning, were limited to the two DG blades, differed dramatically between the blades, and were absent from all other regions. These changes suggested an increase in glutamatergic receptor signaling, and a decrease in GABA receptor signaling, during CFM consolidation. Protein abundance across hippocampal subregions was also differentially impacted by learning and sleep, with most alterations to protein expression restricted to DG. Together, these data suggest that the DG is critical for sleep-dependent memory consolidation, and that the effects of sleep loss on the hippocampus are highly subregion-specific, even within the DG itself.

neuroscience↗

bioRxiv2017

Neutrophil adhesion in brain capillaries contributes to cortical blood flow decreases and impaired memory function in a mouse model of Alzheimer’s disease

The existence of cerebral blood flow (CBF) reductions in Alzheimers disease (AD) patients and related mouse models has been known for decades, but the underlying mechanisms and the resulting impacts on cognitive function and AD pathogenesis remain poorly understood. In the APP/PS1 mouse model of AD we found that an increased number of cortical capillaries had stalled blood flow as compared to wildtype animals, largely due to leukocytes that adhered in capillary segments and blocked blood flow. These capillary stalls were an early feature of disease development, appearing before amyloid deposits. Administration of antibodies against the neutrophil marker Ly6G reduced the number of stalled capillaries, leading to an immediate increase in CBF and to rapidly improved performance in spatial and working memory tasks. Our work has thus identified a cellular mechanism that explains the majority of the CBF reduction seen in a mouse model of AD and has also demonstrated that improving CBF rapidly improved short-term memory function. Restoring cerebral perfusion by preventing the leukocyte adhesion that plugs capillaries may provide a novel strategy for improving cognition in AD patients.

neuroscience↗