Biology subjects

Patel, R. P.

Publications and source records attributed to Patel, R. P..

9 recordsLinked to original sources

bioRxiv2025

Brain lipidomics identifies mitochondrial redox dysfunction and metabolic trade-offs associated with Parkinsons disease-like pathology induced by Nanoplastics exposure

Growing nanoplastics exposure raises concern for neurotoxicity, particularly given recent evidence of plastic accumulation within human brain tissue-a highly lipid enriched organ, yet effects on brain lipid metabolism remains poorly understood. Here, we employed high-resolution untargeted lipidomics to map brain lipid perturbations in Drosophila melanogaster chronically exposed to environmentally relevant levels of polystyrene nanoplastics (NPs). Polystyrene NPs accumulated in fly brains and induced dose-dependent remodeling of mitochondrial membrane lipids, notably cardiolipins and phosphatidylethanolamines, accompanied by increased diacylglycerols/triacylglycerols and monounsaturated fatty acids and by lipid droplet expansion. Guided by these lipidomic signatures, targeted biochemical assays demonstrated depolarized mitochondrial membrane potential, elevated mitochondrial reactive-oxygen species, inhibition of respiratory-chain complexes I and IV, and a shift in NAD(H) and NADP(H) redox couples toward a reduced state and increasing lipid peroxidation. This redox imbalance was accompanied by decreased tyrosine-hydroxylase expression, dopamine depletion, and impaired locomotor behavior, hallmarks of PD-like neurodegeneration. Dopaminergic neurochemistry was impaired (tyrosine hydroxylase and dopamine decreased), with concomitant reduction of GABA, and locomotor and circadian deficits emerged. Remarkbly, co-treatment with the antioxidant N-acetylcysteine (NAC) restored mitochondrial membrane potential, reduced mitochondrial ROS and lipid peroxidation, normalized neutral lipid and MUFA accumulation, and rescued neurotransmitter levels and behavior. Stable-isotope tracing confirmed disrupted TCA cycle flux after NP exposure that was rescued by NAC. Collectively, these findings reveal lipidomic remodeling as a critical link between environmental nanoplastic exposure and PD-like pathology, highlighting mitochondrial redox-lipid interactions as early determinants and support redox-directed interventions to mitigate risk.

neuroscience↗

bioRxiv2025

Harnessing the CD2 axis to broaden and enhance the efficacy of CAR T cell therapies

Patients with T-cell lymphomas and leukemias have overall poor outcomes due to the lack of targeted and effective treatments, particularly in the relapsed and refractory settings. Development of chimeric antigen receptor (CAR) T-cells against T-cell neoplasms is limited by a lack of discriminating T-cell antigens that allow for effective anti-tumor responses while preventing CAR T-cell fratricide. We hypothesized that targeting CD2, a pan-T-cell antigen, using anti-CD2 CAR T-cells engineered without CD2 expression (CART2), would support CAR T-cell manufacturability and preclinical efficacy. Optimized CD2-knockout CART2, generated using CRISPR-Cas9, eradicated primary patient-derived CD2+ hematological neoplasms in vitro and in vivo, secreted effector cytokines, and exhibited adequate proliferative capacity. Nevertheless, CD2 has a key costimulatory function, and its deletion could lead to CAR T-cell dysfunction. Therefore, we tested the role of the CD2:CD58 axis in CAR T-cells, using the anti-CD19 CART models. We demonstrate that CD2 loss attenuates CART19 efficacy by reducing avidity for tumor antigen, co-stimulation, and ultimately in vivo activity. Analogously, we show that tumor CD58 loss reduces CART19 efficacy. To overcome this issue, we developed a novel PD-1:CD2 switch receptor that rescues intracellular CD2 signaling, particularly when PD-L1 is engaged, resulting in improved in vivo outcomes. Collectively, we studied the role of CD2 both as a target for CAR T cell therapy and as a critical costimulatory protein, whose signaling can be rescued using the PD-1:CD2 switch receptor. This receptor can be incorporated into CAR T-cells and provides an effective strategy to overcome CD2-signaling deficiencies.

cancer biology↗

bioRxiv2025

Exposure to rotenone triggers redox driven systemwide lipidome alterations and metabolic tradeoffs linked to Parkinsons disease

With the global rise in aging populations, the increasing incidence of neurodegenerative diseases underscores concerns about brain health, with pesticides like rotenone, emerging as key environmental hazardous. The precise mechanism by which chronic environmental concentration of rotenone exposure causes Parkinson-like phenotype is not understood. Previous studies showed that rotenone induces depletion of dopaminergic neurons by influencing mitochondrial functions. Mitochondrial dysfunction alters lipid homeostasis; therefore, brain lipids can be potential targets for the early risk assessment and prognosis of Parkinsons disease (PD). However, the specific lipidome changes and associated biomarkers of chronic rotenone in vivo exposure causing PD are largely unknown. This study investigates the lipid profile disruptions and biomarkers induced by environmentally relevant concentrations of chronic rotenone exposure using the neuro-model Drosophila melanogaster. An untargeted LC-HRAMS-based lipidomics identified that lipid classes, GP, SP, FA and GL were significantly altered. Furthermore, system-wide loss of cross talk of mitochondrial and peroxisome lipids by altering their redox homeostasis causing PD was observed. Additionally, lipid oxidative stress markers, and behavior abnormalities correlated with altered lipids linked to PD. The findings highlight the rotenone induced complex metabolic trade-offs, prioritizing brains neural integrity at the expense of peripheral lipid levels, leading to PD. Environmental implicationThis study highlights the environmental risks of chronic rotenone exposure, commonly used in agriculture. The findings show that even low concentrations of rotenone disrupt lipid metabolism, particularly in the brain, affecting mitochondrial and peroxisomal functions, contributing to depleting dopaminergic neurons, which are linked to neurodegenerative diseases like Parkinsons. The study also identify lipid markers linked to rotenone induced PD and reveals metabolic trade-offs, where the brain prioritizes neural integrity over peripheral lipid balance. These lipidome changes and redox-driven shifts threaten both individual health and ecosystem stability, emphasizing the need for policies to regulate pesticide use and minimize exposure risks. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/637453v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@145133aorg.highwire.dtl.DTLVardef@1f1612forg.highwire.dtl.DTLVardef@2360f0org.highwire.dtl.DTLVardef@b161f9_HPS_FORMAT_FIGEXP M_FIG Graphical abstract C_FIG

neuroscience↗

bioRxiv2023

Cooperativity between H3.3K27M and PDGFRA poses multiple therapeutic vulnerabilities in human iPSC-derived diffuse midline glioma avatars

Diffuse midline glioma (DMG) is a leading cause of brain tumor death in children. In addition to hallmark H3.3K27M mutations, significant subsets also harbor alterations of other genes, such as TP53 and PDGFRA. Despite the prevalence of H3.3K27M, the results of clinical trials in DMG have been mixed, possibly due to the lack of models recapitulating its genetic heterogeneity. To address this gap, we developed human iPSC-derived tumor models harboring TP53R248Q with or without heterozygous H3.3K27M and/or PDGFRAD842V overexpression. The combination of H3.3K27M and PDGFRAD842V resulted in more proliferative tumors when gene-edited neural progenitor (NP) cells were implanted into mouse brains compared to NP with either mutation alone. Transcriptomic comparison of tumors and their NP cells of origin identified conserved JAK/STAT pathway activation across genotypes as characteristic of malignant transformation. Conversely, integrated genome-wide epigenomic and transcriptomic analyses, as well as rational pharmacologic inhibition, revealed targetable vulnerabilities unique to the TP53R248Q; H3.3K27M; PDGFRAD842V tumors and related to their aggressive growth phenotype. These include AREG-mediated cell cycle control, altered metabolism, and vulnerability to combination ONC201/trametinib treatment. Taken together, these data suggest that cooperation between H3.3K27M and PDGFRA influences tumor biology, underscoring the need for better molecular stratification in DMG clinical trials.

genomics↗

bioRxiv2022

First mitogenome phylogeny of the sun bear Helarctos malayanus reveals a deep split between Indochinese and Sundaic lineages

The sun bear Helarctos malayanus is one of the most endangered ursids, and to date classification of sun bear populations has been based almost exclusively on geographic distribution and morphology. The very few molecular studies focusing on this species were limited in geographic scope. Using archival and non-invasively collected sample material, we have added a substantial number of complete or near-complete mitochondrial genome sequences from sun bears of several range countries of the species distribution. We here report 32 new mitogenome sequences representing sun bears from Cambodia, Thailand, Peninsular Malaysia, Sumatra and Borneo. Reconstruction of phylogenetic relationships revealed two matrilines that diverged [~]290 thousand years ago: one restricted to portions of mainland Indochina (China, Cambodia, Thailand; "Mainland clade"), and one comprising bears from Borneo, Sumatra, Peninsular Malaysia but also Thailand ("Sunda clade"). Generally recent coalescence times in the mitochondrial phylogeny suggest that recent or historical demographic processes have resulted in a loss of mtDNA variation. Additionally, analysis of our data in conjunction with shorter mtDNA sequences revealed that the Bornean sun bear, classified as a distinct subspecies (H. m. euryspilus), does not harbour a distinctive matriline. Further molecular studies of H. malayanus are needed, which should ideally include data from nuclear loci.

genomics↗

bioRxiv2022

Development and validation of PainFace, a software platform that simplifies and standardizes mouse grimace analyses

Facial grimaces are now commonly used to quantify spontaneous pain in mice and other mammalian species, but scoring remains subjective and relies on humans with very different levels of proficiency. Here, we developed a Mouse Grimace Scale (MGS) for black-coated (C57BL/6) mice consisting of four facial action units (orbitals, nose, ears, whiskers). We used this scale to generate ground truth data from over 70,000 images of black mice in different settings. With this large data set, we developed a deep neural network and cloud-based software platform called PainFace (http://painface.net) that accurately scores facial grimaces of black mice on a 0-8 scale. PainFace generates over two orders of magnitude more MGS data than humans can realistically achieve, and at superhuman speed. By analyzing the frequency distribution of grimace scores, we found that mice spent >7x more time in a high grimace state following laparotomy surgery relative to sham surgery controls. The analgesic carprofen reduced the amount of time animals spent in this high grimace state after surgery. Specific facial action unit score combinations were overrepresented following laparotomy surgery, suggesting that characteristic facial expressions are associated with a high grimace state. We performed validation experiments in two labs located in different countries to demonstrate reproducibility of the PainFace platform. To further enhance rigor and reproducibility, we will invite pain researchers to beta test PainFace and then incorporate their feedback into the software and manuscript prior to peer review. While this study is focused on mice, PainFace was designed to simplify, standardize, and scale up grimace analyses with many other mammalian species, including humans.

neuroscience↗

bioRxiv2022

Recapitulation of Human Pathophysiology and Identification of Forensic Biomarkers in a Translational Swine Model of Chlorine Inhalation Injury

RationaleChlorine gas (Cl2) has been repeatedly used as a chemical weapon, first in World War I and most recently in Syria. Life-threatening Cl2 exposures frequently occur in domestic and occupational environments, and in transportation accidents. There is a knowledge gap in large animal models of Cl2-induced acute lung injury (ALI) required to accurately model human etiology and for the development of targeted countermeasures ObjectiveTo develop a translational model of Cl2-induced ALI in swine to study toxico-pathophysiology and identify biomarkers useful for forensic analysis. MethodsSpecific pathogen-free Yorkshire swine (30-40 kg) of either sex were exposed to Cl2 gas ([≤] 240 ppm for 1 h) or filtered air under anesthesia and controlled mechanical ventilation. ResultsExposure to Cl2 resulted in severe hypoxia and hypoxemia, increased airway resistance and peak inspiratory pressure, and decreased dynamic lung compliance. Chlorine exposure resulted in increased total BALF and neutrophil counts, vascular leakage, and edema compared to the control group. The model recapitulated all three key histopathological features of human ALI, such as neutrophilic alveolitis, deposition of hyaline membranes, and formation of microthrombi. Free and lipid-bound 2-chlorofatty acids and chlorotyrosine-modified proteins (3-chloro-L-tyrosine and 3,5-dichloro-L-tyrosine) were detected in plasma and lung after Cl2-exposure. ConclusionsThe translational model developed in this study replicates key features of humans exposed to Cl2 and is suitable to test medical countermeasures. Specific biomarkers of Cl2 exposure have been identified in plasma and lung tissue samples. Take home messageWe developed a swine model of chlorine gas-induced acute lung injury that exhibits several features of human acute respiratory distress syndrome. We validated chlorinated fatty acids and protein adducts in plasma and lung samples as forensic biomarkers.

pharmacology and toxicology↗

bioRxiv2021

Endothelial alpha globin is a nitrite reductase

Small artery vasodilation in response to hypoxia is essential for matching oxygen supply to tissue oxygen demand. One source of hypoxic dilation via nitric oxide (NO) signaling is nitrite reduction by erythrocytic hemoglobin (2{beta}2). However, the alpha subunit of hemoglobin is also expressed in resistance artery endothelium and localized to myoendothelial junctions, a subcellular domain that contacts underlying vascular smooth muscle cells. We hypothesized that nitrite reduction mediated by endothelial alpha globin may occur at myoendothelial junctions to regulate hypoxic vasodilation. To test this concept, we created two novel mouse strains: one lacking alpha globin specifically in endothelium (EC Hba1{Delta}/{Delta}) and one where alpha globin is mutated such that its inhibitory association with endothelial NO synthase (eNOS) is prevented (Hba1WT/{Delta}36-39). In EC Hba1{Delta}/{Delta} or Hba1WT/{Delta}36-39 mice hemoglobin levels, hematocrit and erythrocyte counts were unchanged from littermate controls. Loss of the full alpha globin protein from the endothelium in the EC Hba1{Delta}/{Delta} model was associated with decreased exercise capacity and decreased intracellular nitrite utilization in hypoxic conditions. These effects were not seen in Hba1WT/{Delta}36-39 animals. Hypoxia induced vasodilation was decreased by 60% in isolated thoracodorsal arteries from EC Hba1{Delta}/{Delta}, while infusion of erythrocytes only partially rescued the dilatory response. Lastly, unlike other models where blood pressure is decreased, EC Hba1{Delta}/{Delta} blood pressure was not altered in response to hypoxia. Overall, we conclude that alpha globin in the resistance artery endothelium can act as a nitrite reductase to provide a local vasodilatory response to hypoxia.

physiology↗

bioRxiv2019

Phosgene Inhalation Causes Hemolysis and Acute Lung Injury

Phosgene (Carbonyl Chloride, COCl2) remains an important chemical intermediate in many industrial processes such as combustion of chlorinated hydrocarbons and synthesis of solvents (degreasers, cleaners). It is a sweet smelling gas, and therefore does not prompt escape by the victim upon exposure. Supplemental oxygen and ventilation are the only available management strategies. This study was aimed to delineate the pathogenesis and identify novel biomarkers of acute lung injury post exposure to COCl2 gas. Adult male and female C57BL/6 mice (20-25 g), exposed to COCl2 gas (10 or 20ppm) for 10 minutes in environmental chambers, had a dose dependent reduction in PaO2 and an increase in PaCO2, 1 day post exposure. However, mortality increased only in mice exposed to 20ppm of COCl2 for 10 minutes. Correspondingly, these mice (20ppm) also had severe acute lung injury as indicated by an increase in lung wet to dry weight ratio, extravasation of plasma proteins and neutrophils into the bronchoalveolar lavage fluid, and an increase in total lung resistance. The increase in acute lung injury parameters in COCl2 (20ppm, 10min) exposed mice correlated with simultaneous increase in oxidation of red blood cells (RBC) membrane, RBC fragility, and plasma levels of cell-free heme. In addition, these mice had decreased plasmalogen (plasmenylethanolamine) and elevated levels of their breakdown product, polyunsaturated lysophosphatidylethanolamine, in the circulation suggesting damage to cellular plasma membranes. This study highlights the importance of free heme in the pathogenesis of COCl2 lung injury and identifies plasma membrane breakdown product as potential biomarkers of COCl2 toxicity.

physiology↗