Polymerization of ZBTB transcription factors regulates chromatin occupancy.

BCL6, an oncogenic transcription factor (TF), forms polymers in the presence of a small-molecule molecular glue that stabilizes a complementary interface between homodimers of BCL6's broad-complex, tramtrack, and bric-à-brac (BTB) domain. The BTB domains of other proteins, including a large class of TFs, have similar architectures and symmetries, raising the possibility that additional BTB proteins self-assemble into higher-order structures. Here, we surveyed 189 human BTB proteins with a cellular fluorescent reporter assay and identified 18 ZBTB TFs that show evidence of polymerization. Through biochemical and cryoelectron microscopy (cryo-EM) studies, we demonstrate that these ZBTB TFs polymerize into filaments. We found that BTB-domain-mediated polymerization of ZBTB TFs enhances chromatin occupancy within regions containing homotypic clusters of TF binding sites, leading to repression of target genes. Our results reveal a role of higher-order structures in regulating ZBTB TFs and suggest an underappreciated role for TF polymerization in modulating gene expression.

UBR5 forms ligand-dependent complexes on chromatin to regulate nuclear hormone receptor stability.

Nuclear hormone receptors (NRs) are ligand-binding transcription factors that are widely targeted therapeutically. Agonist binding triggers NR activation and subsequent degradation by unknown ligand-dependent ubiquitin ligase machinery. NR degradation is critical for therapeutic efficacy in malignancies that are driven by retinoic acid and estrogen receptors. Here, we demonstrate the ubiquitin ligase UBR5 drives degradation of multiple agonist-bound NRs, including the retinoic acid receptor alpha (RARA), retinoid x receptor alpha (RXRA), glucocorticoid, estrogen, liver-X, progesterone, and vitamin D receptors. We present the high-resolution cryo-EMstructure of full-length human UBR5 and a negative stain model representing its interaction with RARA/RXRA. Agonist ligands induce sequential, mutually exclusive recruitment of nuclear coactivators (NCOAs) and UBR5 to chromatin to regulate transcriptional networks. Other pharmacological ligands such as selective estrogen receptor degraders (SERDs) degrade their receptors through differential recruitment of UBR5 or RNF111. We establish the UBR5 transcriptional regulatory hub as a common mediator and regulator of NR-induced transcription.

Intranasal Administration of Sugarcane Ash Causes Chronic Kidney Disease in Rats.

Background. Silica nanoparticles found in sugarcane ash have been postulated to be a toxicant contributing to chronic kidney disease of unknown etiology (CKDu). However, while the administration of manufactured silica nanoparticles is known to cause chronic tubulointerstitial disease in rats, the effect of administering sugarcane ash on kidney pathology remains unknown. Here we investigate whether sugarcane ash can induce CKD in rats. Methods. Sugarcane ash was administered for 13 weeks into the nares of rats (5 mg/day for 5d/week), and blood, urine and kidney tissues were collected at 13 weeks (at the end of ash administration) and in a separate group of rats at 24 weeks (11 weeks after stopping ash administration). Kidney histology was evaluated, and inflammation and fibrosis (collagen deposition) measured. Results. Sugarcane ash exposure led to the accumulation of silica in the kidneys, lungs, liver and spleen of rats. Mild proteinuria developed although renal function was largely maintained. However, biopsies showed focal glomeruli with segmental glomerulosclerosis, and tubulointerstitial inflammation and fibrosis that tended to worsen even after the ash administration had been stopped. Staining for the lysosomal marker, LAMP-1, showed decreased staining in ash administered rats consistent with lysosomal activation. Conclusion. Sugarcane ash containing silica nanoparticles can cause CKD in rats.

Health burden of sugarcane burning on agricultural workers and nearby communities.

Sugarcane is the most widely cultivated crop in the world, with equatorial developing nations performing most of this agriculture. Burning sugarcane is a common practice to facilitate harvest, producing extremely high volumes of respirable particulate matter in the process. These emissions are known to have deleterious effects on agricultural workers and nearby communities, but the extent of this exposure and potential toxicity remain poorly characterized. As the epidemicof chronic kidney disease of an unknown etiology (CKDu) and its associated mortality continue to increase along with respiratory distress, there is an urgent need to investigate the causes, determine viable interventions to mitigate disease andimprove outcomes for groups experiencing disproportionate impact. The goal of this review is to establish the state of available literature, summarize what is known in terms of human health risk, and provide recommendations for what areas should be prioritized in research.

Climate change and nephrology.

Climate change should be of special concern for the nephrologist, as the kidney has a critical role in protecting the host from dehydration, but it is also a favorite target of heat stress and dehydration. Here we discuss how rising temperatures and extreme heat events may affect the kidney. The most severe presentation of heat stress is heat stroke, which can result in severe electrolyte disturbance and both acute and chronic kidney disease (CKD). However, lesser levels of heat stress also have multiple effects, including exacerbating kidney disease and precipitating cardiovascular events in subjects with established kidney disease. Heat stress can also increase the risk for kidney stones, cause multiple electrolyte abnormalities and induce both acute and chronic kidney disease. Recently there have been multiple epidemics of CKD of uncertain etiology in various regions of the world, including Mesoamerica, Sri Lanka, India and Thailand. There is increasing evidence that climate change and heat stress may play a contributory role in these conditions, although other causes, including toxins, could also be involved. As climate change worsens, the nephrologist should prepare for an increase in diseases associated with heat stress and dehydration.

Case series profile of olanzapine post-injection delirium/sedation syndrome.

Olanzapine pamoate is an intramuscular depot injection for the treatment of schizophrenia. Approximately 1.4% of patients develop a serious adverse event called post-injection delirium/sedation syndrome (PDSS), characterised by drowsiness, anticholinergic and extrapyramidal symptoms. The objective is to investigate olanzapine PDSS presentations including clinical features and treatment approach. This is a retrospective review of olanzapine PDSS patients from three toxicology units and the NSW Poisons Information Centre between 2017 and 2022. Adult patients were included if they had intramuscular olanzapine then developed PDSS criteria. Clinical symptoms, treatment, timing and length of symptoms were extracted into a preformatted Excel database. There were 18 patients included in the series, with a median age of 49 years (interquartile range [IQR]: 38-58) and male predominance (89%). Median onset time post injection was 30 min (IQR: 11-38). PDSS symptoms predominate with drowsiness, confusion and dysarthria. Median length of symptoms was 24 h (IQR: 20-54). Most common treatment included supportive care without any pharmacological intervention (n = 10), benzodiazepine (n = 4) and benztropine (n = 3). In one case, bromocriptine and physostigmine followed by oral rivastigmine were given to manage antidopaminergic and anticholinergic symptoms respectively. This proposed treatment combination could potentially alleviate some of the symptoms but needs further studies to validate the findings. In conclusion, this case series supports the characterisation of PDSS symptomology predominantly being anticholinergic with similar onset (<1 h) and duration (<72 h). Bromocriptine is proposed to manage PDSS if patients develop severe dopamine blockade and physostigmine followed by rivastigmine for anticholinergic delirium.

Metabolic Consequences of IgE- and Non-IgE-Mediated Mast Cell Degranulation.

Mast cells are important effector cells in the immune system and undergo activation (i.e., degranulation) by two major mechanisms: IgE-mediated and non-IgE-mediated mechanisms. Although IgE-mediated degranulation is well researched, the cellular mechanisms of non-IgE-mediated mast cell activation are poorly understood despite the potential to induce similar pathophysiological effects. To better understand non-IgE mast cell degranulation, we characterized and compared cellular metabolic shifts across several mechanisms of degranulation (allergen-induced [IgE-mediated], 20 nm of silver nanoparticle-mediated [non-IgE], and compound 48/80-mediated [non-IgE]) in murine bone marrow-derived mast cells. All treatments differentially impacted mitochondrial activity and glucose uptake, suggesting diverging metabolic pathways between IgE- and non-IgE-mediated degranulation. Non-IgE treatments depleted mast cells' glycolytic reserve, and compound 48/80 further inhibited the ability to maximize mitochondrial respiration. This cellular reprogramming may be indicative of a stress response with non-IgE treatments. Neither of these outcomes occurred with IgE-mediated degranulation, hinting at a separate programmed response. Fuel flexibility between the three primary mitochondrial nutrient sources was also eliminated in activated cells and this was most significant in non-IgE-mediated degranulation. Lastly, metabolomics analysis of bone marrow-derived mast cells following degranulation was used to compare general metabolite profiles related to energetic pathways. IgE-mediated degranulation upregulated metabolite concentrations for the TCA cycle and glycolysis compared with other treatments. In conclusion, mast cell metabolism varies significantly between IgE- and non-IgE-mediated degranulation suggesting novel cell regulatory mechanisms are potentially driving unexplored pathways of mast cell degranulation.

Prenatal exposure to poly- and perfluoroalkyl substances and the incidence of asthma in early childhood.

EXPOSURE TO POLY: and perfluoroalkyl substances (PFAS) in early life may increase the risk of childhood asthma, but evidence has been inconsistent. We estimated associations between maternal serum concentrations of PFAS during pregnancy and clinician-diagnosed asthma incidence in offspring through age eight. We included 597 mother-child pairs with PFAS quantified in mid-pregnancy serum and childhood medical records reviewed for asthma diagnoses. We used separate Cox proportional hazards models to assess the relationship between log-transformed concentrations of five PFAS and the incidence of asthma. We estimated associations between the PFAS mixture and clinician-diagnosed asthma incidence using quantile-based g-computation. PFAS concentrations were similar to those among females in the US general population. Seventeen percent of children (N = 104) were diagnosed with asthma during follow-up. Median (interquartile range) duration of follow-up was 4.7 (4.0, 6.2) years, and median age at asthma diagnosis was 1.7 (0.9, 2.8) years. All adjusted hazard ratios (HRs) were elevated, but all 95% confidence intervals (CI) included the null. The HR (95% CI) of asthma for a one-quartile increase in the PFAS mixture was 1.17 (0.86, 1.61). In this cohort of children followed to eight years of age, prenatal PFAS concentrations were not significantly associated with incidence of clinician-diagnosed asthma.

Inhaled silica nanoparticles cause chronic kidney disease in rats.

Silica nanoparticles (SiNPs) released during the burning of sugarcane have been postulated to have a role in chronic kidney disease of unknown etiology. We tested the hypothesis that pristine SiNPs of the size present in sugarcane might cause chronic kidney injury when administered through the lung in rats. We administered 200- or 300-nm amorphous SiNPs twice weekly (4 mg/dose), or vehicle by oropharyngeal aspiration for 13 wk to rats followed by euthanasia after an additional 13 wk (26 wk total). Tissues were evaluated for the presence of SiNPs and evidence of histological injury. Both sizes of SiNPs caused kidney damage, with early tubular injury and inflammation (at week 13) that continued to inflammation and chronic fibrosis at week 26 despite discontinuation of the SiNP administration. Both sizes of SiNPs caused local inflammation in the lung and kidney and were detected in the serum and urine at week 13, and the 200-nm particles were also localized to the kidney with no evidence of retention of the 300-nm particles. At week 26, there was some clearance of the 200-nm silica from the kidneys, and urinary levels of SiNPs were reduced but still significant in both 200- and 300 nm-exposed rats. In conclusion, inhaled SiNPs cause chronic kidney injury that progresses despite stopping the SiNP administration. These findings support the hypothesis that human exposure to amorphous silica nanoparticles found in burned sugarcane fields could have a participatory role in chronic kidney disease of unknown etiology.NEW & NOTEWORTHY Inhalation of silica nanoparticles (SiNPs) released during the burning of sugarcane has been postulated to have a role in chronic kidney disease of unknown etiology (CKDu). We administered 200- and 300-nm amorphous SiNPs to rats by aspiration and observed kidney damage with tubular injury and inflammation that persisted even after stopping the SiNP exposure. These findings support the hypothesis that human exposure to SiNPs found in sugarcane ash could have a participatory role CKDu.

Normalization by distributional resampling of high throughput single-cell RNA-sequencing data.

MOTIVATION: Normalization to remove technical or experimental artifacts is critical in the analysis of single-cell RNA-sequencing experiments, even those for which unique molecular identifiers are available. The majority of methods for normalizing single-cell RNA-sequencing data adjust average expression for library size (LS), allowing the variance and other properties of the gene-specific expression distribution to be non-constant in LS. This often results in reduced power and increased false discoveries in downstream analyses, a problem which is exacerbated by the high proportion of zeros present in most datasets. RESULTS: To address this, we present Dino, a normalization method based on a flexible negative-binomial mixture model of gene expression. As demonstrated in both simulated and case study datasets, by normalizing the entire gene expression distribution, Dino is robust to shallow sequencing, sample heterogeneity and varying zero proportions, leading to improved performance in downstream analyses in a number of settings. AVAILABILITY AND IMPLEMENTATION: The R package, Dino, is available on GitHub at https://github.com/JBrownBiostat/Dino. The Dino package is further archived and freely available on Zenodo at https://doi.org/10.5281/zenodo.4897558. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Interspecies chimeric conditions affect the developmental rate of human pluripotent stem cells.

Human pluripotent stem cells hold significant promise for regenerative medicine. However, long differentiation protocols and immature characteristics of stem cell-derived cell types remain challenges to the development of many therapeutic applications. In contrast to the slow differentiation of human stem cells in vitro that mirrors a nine-month gestation period, mouse stem cells develop according to a much faster three-week gestation timeline. Here, we tested if co-differentiation with mouse pluripotent stem cells could accelerate the differentiation speed of human embryonic stem cells. Following a six-week RNA-sequencing time course of neural differentiation, we identified 929 human genes that were upregulated earlier and 535 genes that exhibited earlier peaked expression profiles in chimeric cell cultures than in human cell cultures alone. Genes with accelerated upregulation were significantly enriched in Gene Ontology terms associated with neurogenesis, neuron differentiation and maturation, and synapse signaling. Moreover, chimeric mixed samples correlated with in utero human embryonic samples earlier than human cells alone, and acceleration was dose-dependent on human-mouse co-culture ratios. The altered gene expression patterns and developmental rates described in this report have implications for accelerating human stem cell differentiation and the use of interspecies chimeric embryos in developing human organs for transplantation.

Nanostructured carbon-fiber surfaces for improved neurochemical detection.

Fundamental insight into the extent to which the nanostructured surface and geometry impacts neurochemical interactions at electrode surfaces could provide significant advances in our ability to design and fabricate ultrasensitive neurochemical detection probes. Here, we investigate the extent to which the nanostructure of the carbon-fiber surface impacts detection of catecholamines and purines with fast-scan cyclic voltammetry (FSCV). Carbon-fibers were treated with argon (Ar) plasma to induce variations in the nano- and micro-structure without changing the functionalization of the surface. We tested variations in topology by measuring the extent to which the flow rate, RF power, and treatment time affect the surface roughness. Flow rates from 50-100 sccm, plasma power from 20-100 W, and treatment times from 30 s to 5 min were compared. Two Ar-treatments were chosen from the optimization studies for comparison, and the surface roughness was evaluated using atomic force microscopy (AFM). To ensure no changes in chemical composition, fibers were analyzed with X-ray photoelectron spectroscopy (XPS). On average, at the optimized Ar-plasma treatment procedure, oxidative current for adenosine and ATP increased by 3.5 ± 1.4-fold and 3.2 ± 0.6-fold, and guanosine and GTP by 1.7 ± 0.3-fold and 1.8 ± 0.3-fold, respectively (n = 9). Dopamine increased by 1.7 ± 0.3-fold. The extent to which changes in the electrode structure impact adsorption, sensitivity, and electron transfer rates were measured. A COMSOL Multiphysics simulation was developed to enable the modeling of mass transport of electroactive species at varying electrode geometries. Overall, this study provides critical insight into the extent to which the nanostructure of the surface impacts the electrochemical detection of neurochemicals.

Optimising alkalinisation and its effect on QRS narrowing in tricyclic antidepressant poisoning.

AIMS: The objectives were to determine the effect of NaHCO3 and/or mechanical ventilation on the biochemical profile and serum alkalinisation in tricyclic antidepressant (TCA) poisoning and investigate the impact of effective alkalinisation therapy on the QRS interval in TCA poisoning. METHODS: This was a retrospective review of TCA poisonings from three Australian toxicology units and a poisons information centre (Jan 2013 to Jan 2019). We included patients with TCA toxicity who ingested>10 mg/kg or had clinically significant toxicities consistent with TCA poisoning, and analysed patients' clinical, electrocardiogram and biochemical data. RESULTS: Of 210 patients, 84 received NaHCO3 and ventilation (dual therapy), 12 NaHCO3 , 46 ventilation and 68 supportive care treatment. When compared with single/supportive groups, patients who received dual therapy had taken a significantly higher median dose of TCA (1.5 g vs1.3 g, P < .001), a longer median maximum QRS interval (124 ms, interquartile ranges [IQR] 108-138 vs106 ms, IQR 98-115, P < .001) and were more likely to have seizures (14% vs3%, P = .006) and arrhythmias (17% vs1%, P < .001). The dual therapy group demonstrated greater increases in serum pH (median 0.11, IQR 0.04-0.17) compared to the single/supportive therapy group (median 0.03, IQR -0.01-0.09, p < .001). A greater proportion of patients reached the target pH 7.45-7.55 in the dual therapy group (59%) compared to the single/supportive therapy group (10%) (P < .001). For each 100 mmol bolus of NaHCO3 given, the median increase in serum sodium was 2.5 mmol/L (IQR 1.5-4.0). QRS narrowing occurred twice as quickly in the dual therapy vs single/supportive therapy group. CONCLUSIONS: A combination of NaHCO3 and mechanical ventilation was most effective in achieving serum alkalinisation and was associated with a more rapid narrowing of the QRS interval. We advise that the maximal dose of NaHCO3 should be <400 mmol (6 mmol/kg).

A review of chemical warfare agents linked to respiratory and neurological effects experienced in Gulf War Illness.

Over 40% of veterans from the Persian Gulf War (GW) (1990-1991) suffer from Gulf War Illness (GWI). Thirty years since the GW, the exposure and mechanism contributing to GWI remain unclear. One possible exposure that has been attributed to GWI are chemical warfare agents (CWAs). While there are treatments for isolated symptoms of GWI, the number of respiratory and cognitive/neurological issues continues to rise with minimum treatment options. This issue does not only affect veterans of the GW, importantly these chronic multisymptom illnesses (CMIs) are also growing amongst veterans who have served in the Afghanistan-Iraq war. What both wars have in common are their regions and inhaled exposures. In this review, we will describe the CWA exposures, such as sarin, cyclosarin, and mustard gas in both wars and discuss the various respiratory and neurocognitive issues experienced by veterans. We will bridge the respiratory and neurological symptoms experienced to the various potential mechanisms described for each CWA provided with the most up-to-date models and hypotheses.

Changes in sales of analgesics to pharmacies after codeine was rescheduled as a prescription only medicine.

OBJECTIVE: To investigate changes in sales to pharmacies of over-the-counter (OTC) and prescription analgesics, cold and flu products, and cough suppressants after the rescheduling of codeine as a prescription only medicine in February 2018. DESIGN: Interrupted time series analysis of sales to pharmacies. SETTING: Pharmaceutical sales to community pharmacies in Australia, March 2015 - March 2019. The period January 2017 (month after rescheduling was announced) to January 2018 (month before rescheduling was implemented) was excluded from the time series analysis. MAIN OUTCOME MEASURES: Monthly pack and tablet sales per 10 000 population of OTC and prescription analgesics, cold and flu products, and cough suppressants. RESULTS: During 2016, 7586 packs and 248 127 tablets of OTC codeine per 10 000 population were sold to pharmacies; in the 14 months after rescheduling, a small level increase in monthly prescription codeine sales was evident (2247 tablets/capsules per 10 000 population; 95% CI, 1231-3264 per 10 000 population). Monthly OTC analgesic sales increased by 258 (95% CI, 151-365) packs per 10 000 population and 37 856 (95% CI, 26 143-49 569) tablet/capsules per 10 000 population. Monthly sales of single ingredient paracetamol (41 415 [95% CI, 31 374-51 456] tablets/capsules per 10 000 population), ibuprofen (1392 [95% CI 916-1868] tablets/capsules per 10 000 population), paracetamol/ibuprofen (1618 tablets [95% CI, 1567-1669] tablets/capsules per 10 000 population), and other paracetamol combinations (233 [95% CI, 112-353] tablets/capsules per 10 000 population) all increased, but not those of prescription analgesic products not containing codeine. Rises for OTC cold/flu products containing the opioid derivative dextromethorphan were small; sales of OTC cough suppressants containing opioid derivatives (dextromethorphan, pholcodine, dihydrocodeine) did not change. CONCLUSIONS: The rescheduling of codeine was followed by increased sales to pharmacies of paracetamol, ibuprofen, and paracetamol combination products. While these products carry no risk of dependence, their inappropriate use is also associated with harms that warrant adverse event monitoring.

Exposure to silver nanoparticles primes mast cells for enhanced activation through the high-affinity IgE receptor.

Mast cells are a key effector cell in type I allergic reactions. It has been shown that environmental exposures such as diesel exhaust and heavy metals exacerbate mast cell degranulation and activation. Today, the use of engineered nanomaterials (ENMs) is rapidly expanding and silver nanoparticles (AgNP) are one of the mostly widely utilized ENMs, primarily for their antimicrobial properties, and are being incorporated into many consumer and biomedical products. We assessed whether pre-exposure of bone marrow-derived mast cells (BMMCs) to 20 nm AgNPs enhanced degranulation and activation to an allergen (dinitrophenol-conjugated human serum albumin) by measuring ß-hexosaminidase release, LTB4 and IL-6 production. In addition, we assessed reactive oxygen species (ROS) generation, cell oxidative stress and toxicity as well as total and individual protein tyrosine phosphorylation (p-Tyr). We found that pre-exposure of BMMCs to AgNPs results in exacerbated allergen-mediated mast cell degranulation, LTB4 production and IL-6 release. Exposure of BMMCs to AgNPs exacerbated allergen-induced ROS generation, however, this was not associated with oxidative stress nor cell death. Finally, pre-exposure to AgNPs enhanced allergen-mediated global p-Tyr as well as individual proteins including Syk, PLCγ and LAT. Our findings indicate that pre-exposure to AgNPs exacerbates mast cell allergen-mediated phosphorylation of FcεR1-linked tyrosine kinases and ROS generation resulting in amplified early and late-phase responses. These findings suggest that exposure to AgNPs has the potential to prime mast cells to allergic immune responses, which could be of particular concern to atopic populations as the use of AgNPs in consumer and biomedical products rapidly increases.

Paracetamol poisoning-related hospital admissions and deaths in Australia, 2004-2017.

OBJECTIVES: To assess the numbers of paracetamol overdose-related hospital admissions and deaths in Australia since 2007-08, and the overdose size of intentional paracetamol overdoses since 2004. DESIGN, SETTING: Retrospective analysis of data on paracetamol-related exposures, hospital admissions, and deaths from the Australian Institute of Health and Welfare National Hospital Morbidity Database (NHMD; 2007-08 to 2016-17), the New South Wales Poisons Information Centre (NSWPIC; 2004-2017), and the National Coronial Information System (NCIS; 2007-08 to 2016-17). PARTICIPANTS: People who took overdoses of paracetamol in single ingredient preparations. MAIN OUTCOME MEASURES: Annual numbers of reported paracetamol-related poisonings, hospital admissions, and deaths; number of tablets taken in overdoses. RESULTS: The NHMD included 95 668 admissions with paracetamol poisoning diagnoses (2007-08 to 2016-17); the annual number of cases increased by 44.3% during the study period (3.8% per year; 95% CI, 3.2-4.6%). Toxic liver disease was documented for 1816 of these patients; the annual number increased by 108% during the study period (7.7% per year; 95% CI, 6.0-9.5%). The NSWPIC database included 22 997 reports of intentional overdose with paracetamol (2004-2017); the annual number increased by 77.0% during the study period (3.3% per year; 95% CI, 2.5-4.2%). The median number of tablets taken increased from 15 (IQR, 10-24) in 2004 to 20 (IQR, 10-35) in 2017. Modified release paracetamol ingestion report numbers increased 38% between 2004 and 2017 (95% CI, 30-47%). 126 in-hospital deaths were recorded in the NHMD, and 205 deaths (in-hospital and out of hospital) in the NCIS, with no temporal trends. CONCLUSIONS: The frequency of paracetamol overdose-related hospital admissions has increased in Australia since 2004, and the rise is associated with greater numbers of liver injury diagnoses. Overdose size and the proportion of overdoses involving modified release paracetamol have each also increased.

Biocorona formation contributes to silver nanoparticle induced endoplasmic reticulum stress.

Prior research has demonstrated cells exposed to silver nanoparticles (AgNPs) undergo endoplasmic reticulum (ER) stress leading to cellular apoptosis and toxicity, however, the fundamental mechanism underlying AgNP-induced ER stress is unknown. We hypothesize the biophysical interactions between AgNPs and adsorbed proteins lead to misfolded proteins to elicit an ER stress response. Our investigation examined rat aortic endothelial cells (RAEC) exposed to 20 or 100 nm AgNPs with or without a biocorona (BC) consisting of bovine serum albumin (BSA), high density lipoprotein (HDL) or fetal bovine serum (FBS) to form a complex BC. The presence of a BC consisting of BSA or FBS proteins significantly reduced uptake of 20 nm and 100 nm AgNPs in RAEC. Western blot analysis indicated robust activation of the IREα and PERK pathways in RAEC exposed to 20 nm despite the reduction in uptake by the presence of a BC. This was not observed for the 100 nm AgNPs. Hyperspectral darkfield microscopy qualitatively confirmed that the preformed BC was maintained following uptake by RAEC. Transmission electron microscopy demonstrated a size dependent effect on the sub-cellular localization of AgNPs. Overall, these results suggest that AgNP size, surface area and BC formation governs the induction of ER stress and alterations in intracellular trafficking.