Biology subjects

Gibson-Corley, K.

Publications and source records attributed to Gibson-Corley, K..

7 recordsLinked to original sources

bioRxiv2026

Safety of Subdural Direct Current Stimulation: A Histological Study in the Ovine Brain

BackgroundDirect current (DC) stimulation can modulate neuronal activity in ways that differ from pulsatile stimulation, but its intracranial use has been limited by concerns about tissue injury at the electrode/tissue interface. Quantitative safety limits for DC delivered through metal electrodes directly to the brain remain poorly defined. ObjectiveTo estimate histological safety boundaries for DC stimulation delivered through metal electrodes in a large-brain gyrencephalic animal model. MethodsCathodal DC stimulation was applied to the exposed cortical surface of ten anesthetized sheep using platinum-iridium disc electrodes typically used in clinical applications (surface area [≤] 4.15 mm2). Currents of 5 to 1000 {micro}A were delivered for 10 to 15 minutes at 36 cortical sites. Stimulation dose was quantified as charge density. Brains were removed shortly after stimulation and examined histologically for tissue damage, including necrosis, inflammation, gliosis, and demyelination. Lesion volumes were quantified and related to charge density. ResultsNo lesions were observed at sites where no current or a low charge density (0.7 mC/mm2) was delivered. With stimulation, lesion probability and volume increased with charge density, although variability was substantial. Lesions occurred in 3 of 18 sites at lower charge densities (1.4 to 10 mC/mm2) and in 5 of 9 sites at higher charge densities (14.4 to 144.4 mC/mm2). Linear regression of lesion volume against charge density yielded an estimated zero-lesion intercept of 2.3 mC/mm2, whereas alternative nonlinear models predicted thresholds up to 8.7 mC/mm2. ConclusionThese findings suggest that it may be possible to apply cathodal DC stimulation directly to the cortical surface through metal electrodes without detectable histological damage when current intensity, duration, and electrode size are appropriately constrained. These findings provide quantitative guidance for the safe application of DC directly to neural tissue in experimental and translational neuromodulation studies.

neuroscience↗

bioRxiv2024

Mitochondrial Fatty Acid Synthesis and Mecr Regulate CD4+ T Cell Function and Oxidative Metabolism

SummaryWe show that the mitochondrial fatty acid synthesis gene Mecr shapes CD4+ T cell metabolism and function. It may be targeted in inflammatory diseases and provides rationale to consider the immunological state of patients with mitochondrial disease. Lipid metabolism is fundamental to CD4+ T cell metabolism yet remains poorly understood across subsets. Therefore, we performed targeted in vivo CRISPR/Cas9 screens to identify lipid-associated genes essential for T cell subset functions. These screens established mitochondrial fatty acid synthesis (mtFAS) genes Mecr, Mcat and Oxsm as highly impactful. Of these, the inborn error of metabolism gene Mecr was most dynamically regulated. Effector and memory T cells were reduced in Mecrfl/fl; Cd4cre mice, and MECR was required for activated CD4+ T cells to efficiently proliferate, differentiate, and survive. Mecr-deficient T cells also had decreased mitochondrial respiration, reduced TCA intermediates, and accumulated intracellular iron, which contributed to cell death and sensitivity to ferroptosis. Importantly, Mecr-deficient T cells exhibited fitness disadvantages in inflammatory, tumor, and infection models. mtFAS and MECR thus play important roles in activated T cells and may provide targets to modulate immune functions in inflammatory diseases. The immunological state of MECR- and mtFAS-deficient patients may also be compromised.

immunology↗

bioRxiv2024

Epithelial IL-2 is critical for NK cell-mediated cancer immunosurveillance in mammary glands

Interleukin 2 (IL-2) is the first identified cytokine and its interaction with receptors has been known to shape the immune responses in many lymphoid or non-lymphoid tissues for more than four decades. Active T cells are the primary cellular source for IL-2 production and epithelial cells have never been considered the major cellular source of IL-2 under physiological conditions. It is, however, tempting to speculate that epithelial cells could potentially express IL-2 that regulates the intricate interactions between epithelial cells and lymphocytes. Datamining our recently published single-cell RNAseq in the mouse mammary gland identified IL-2 expression in mammary epithelial cells, which is induced by prolactin via the STAT5 signaling pathway. Furthermore, epithelial IL-2 plays a crucial role in maintaining the physiological functions of natural killer (NK) cells within the mammary glands. IL-2 deletion in the mammary epithelial cells leads to a significant reduction in the number and function of NK cells, which in turn results in defective immunosurveillance, expansion of luminal epithelial cells, and tumor development. Interestingly, T cells in the mammary glands are not changed, indicating the specific regulation of NK cells by epithelial IL-2 production. In agreement, we also found that human epithelial cells express IL-2 and NK cells express the highest level of IL2RB among all the immune cells. Here, we provide the first evidence that epithelial cells produce IL-2, which is critical for maintaining the physiological functions of NK cells in immunosurveillance.

immunology↗

bioRxiv2024

STING-Activating Polymer-Drug Conjugates for Cancer Immunotherapy

The stimulator of interferon genes (STING) pathway links innate and adaptive antitumor immunity and therefore plays an important role in cancer immune surveillance. This has prompted widespread development of STING agonists for cancer immunotherapy, but pharmacological barriers continue to limit the clinical impact of STING agonists and motivate the development of drug delivery systems to improve their efficacy and/or safety. To address these challenges, we developed SAPCon, a STING-activating polymer-drug conjugate platform based on strain-promoted azide-alkyne cycloaddition of dimeric-amidobenzimidazole (diABZI) STING agonists to hydrophilic polymer chains through an enzyme-responsive chemical linker. To synthesize a first-generation SAPCon, we designed a diABZI prodrug modified with a DBCO reactive handle with a cathepsin B-cleavable spacer for intracellular drug release and conjugated this to pendant azide groups on a 100kDa poly(dimethyla acrylamide-co-azide methacrylate) copolymer backbone to increase circulation time and enable passive tumor accumulation. We found that intravenously administered SAPCon accumulated at tumor sites, where it was endocytosed by tumor-associated myeloid cells, resulting in increased STING activation in tumor tissue. Consequently, SAPCon promoted an immunogenic tumor microenvironment, characterized by increased frequency of activated macrophages and dendritic cells and improved infiltration of CD8+ T cells, resulting in inhibition of tumor growth, prolonged survival, and enhanced response to anti-PD-1 immune checkpoint blockade in orthotopic breast cancer models. Collectively, these studies position SAPCon as a modular and programmable platform for improving the efficacy of systemically administered STING agonists for cancer immunotherapy.

bioengineering↗

bioRxiv2024

The 4T1 breast carcinoma model possesses hybrid epithelial/mesenchymal traits linked to a highly metastatic phenotype

Epithelial-mesenchymal transitions (EMTs) have emerged as a mechanism for carcinomas to gain metastatic capabilities. As classically defined, EMTs entail downregulation of E-cadherin, viewed as a master enforcer of an epithelial phenotype, and upregulation of mesenchymal markers such as N-cadherin and vimentin. Contrary to this, E-cadherin appears to be retained in many invasive carcinomas and promote collective cell invasion. Therefore, major questions remain concerning the role of E-cadherin in metastasis. To investigate how E-cadherin regulates metastasis, we selected murine 4T1 breast carcinoma cells, a widely utilized model of stage IV metastatic breast cancer that retains E-cadherin expression. Using RNA interference and constitutive expression, we demonstrate that the expression level of E-cadherin does not determine 4T1 metastatic capacity in mice. Despite high levels of expression, E-cadherin is unable to confer an epithelial phenotype with stable organized cell-cell junctions. Moreover, orthotopic 4T1 tumors in mice display co-expression of E-cadherin and vimentin and contain subregions of EMT-like loss of E-cadherin. In addition, we find that 4T1 cells co-express epithelial and mesenchymal isoforms of p120-catenin. These findings support 4T1 cells as a model for carcinomas that possess hybrid traits of epithelial and mesenchymal states that promote invasion and metastasis. As such, the 4T1 model provides a platform for investigating strategies to reinstate E-cadherins ability to promote stable cell-cell junctions in E-cadherin-positive cancers, and for identifying which aspects of an epithelial phenotype may serve to facilitate the macroscopic growth of metastatic colonies.

cancer biology↗

bioRxiv2022

IL-17A controls CNS autoimmunity by regulating gut microbiota and inducing regulatory T cells

A disrupted equilibrium among gut microbiota, IL-17A-producing CD4 T-cells (Th17), and regulatory CD4 T-cells (Treg) have been linked with the pathobiology of multiple sclerosis (MS). While gut microbiota can regulate both Treg and Th17 cells, the impact of IL-17A on this gut-immune connection remains unclear. Utilizing HLA-DR3 transgenic mouse model of MS, we show that IL-17A deficiency (HLA-DR3.IL17A-/-) resulted in milder disease characterized by increased Tregs and expansion of Treg-promoting gut microbes, including Prevotella. Cohousing HLA-DR3 mice with HLA-DR3.IL17A-/- transferred the milder disease phenotype and associated microbiota changes to DR3 mice, highlighting the dominant role of gut microbiota in Treg induction and disease amelioration. DR3.IL17A-/- mice also showed a higher abundance of functional pathways linked with short-chain fatty acid synthesis and elevated IL-10 in dendritic cells. Enrichment of the Treg-promoting PPAR signaling pathway expression in the colon of HLA-DR3.IL17A-/- mice and following Prevotella administration in HLA-DR3 mice underscores the importance of gut microbiota in IL-17A-mediated immune regulation. Thus, our study uncovers a previously unappreciated role for IL-17A in shaping gut microbiota and immune regulation, with far-reaching implications for MS treatment. One-Sentence SummaryIL-17A modulates Treg and gut microbiota to control EAE

immunology↗

bioRxiv2021

Leishmania infantum xenodiagnosis from vertically infected dogs reveals significant skin tropism

BackgroundDogs are the primary reservoir for human visceral leishmaniasis due to Leishmania infantum. Phlebotomine sand flies maintain zoonotic transmission of parasites between dogs and humans. A subset of dogs is infected transplacentally during gestation, but at what stage of the clinical spectrum vertically infected dogs contribute to the infected sand fly pool is unknown. Methodology/Principal FindingsWe examined infectiousness of dogs vertically infected with L. infantum from multiple clinical states to the vector Lutzomyia longipalpis using xenodiagnosis and found that vertically infected dogs were infectious to sand flies at differing rates. Dogs with moderate disease showed significantly higher transmission to the vector than dogs with very mild or severe disease. We documented a substantial parasite burden in the skin of vertically infected dogs by RT-qPCR, despite these dogs not having received intradermal parasites via sand flies. There was a highly significant correlation between skin parasite burden at the feeding site and sand fly parasite uptake. This suggests dogs with high skin parasite burden contribute the most to the infected sand fly pool. Although skin parasite load and parasitemia correlated with one another, the average parasite number detected in skin was significantly higher compared to blood in matched subjects. Thus, dermal resident parasites were infectious to sand flies from dogs without detectable parasitemia. Conclusions/SignificanceTogether, our data implicate skin parasite burden and earlier clinical status as stronger indicators of outward transmission potential than blood parasite burden. Our studies of a population of dogs without vector transmission highlights the need to consider canine vertical transmission in surveillance and prevention strategies. AUTHOR SUMMARYSand flies transmit Leishmania parasites between infected dogs and humans leading to the life-threatening tropical disease Visceral Leishmaniasis (VL). Identifying which dogs transmit parasites well to sand flies is important to curb disease spread. The offspring of both dogs and humans can also be infected vertically while in utero. Despite this, the infectiousness of dogs that receive parasites in utero to sand flies has not been thoroughly investigated. Thus, we allowed sand flies to feed on a group of vertically infected dogs at varying stages of VL disease severity and measured sand fly parasite uptake. We found vertically infected dogs were readily able to transmit parasites to the sand flies. Dogs that were most infectious had moderate clinical disease and relatively high levels of parasite infection in their blood and skin. However, the level of skin infection was significantly higher than that observed in the blood, and the skin parasite load had the strongest correlation with sand fly parasite uptake. This implicates the skin may be an underappreciated driver of canine infectiousness to the sand fly vector. In addition, this work highlights that vertically infected dogs are very important parts of the transmission cycle and must be considered in all public health efforts addressing VL.

microbiology↗