Biology subjects

Le, T. H.

Publications and source records attributed to Le, T. H..

8 recordsLinked to original sources

bioRxiv2025

Per- and Polyfluoroalkyl Substances Induces Salt-Sensitive Hypertension by Upregulating Epithelial Sodium Channel - The First Experimental Evidence Supporting Causality

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals found in the plasma of 98% of Americans. Epidemiological studies associate PFAS exposure with hypertension and kidney dysfunction, but causality and mechanisms remain unclear. We examined the effects of a mixture of 4 PFAS commonly detected in humans, including PFOA, PFOS, PFHxS, and PFNA, on blood pressure, salt sensitivity, and renal injury in 129S6 mice. Exposure to a lower dose for 3 weeks produced plasma PFAS levels in mice resembling occupational and regional environmental exposures; while a upper dose achieved levels similar to PFAS production workers. PFAS induced dose-dependent pressor effects in male but not female mice on a 0.4% low salt diet. During 4% high salt feeding, PFAS induced greater salt-sensitive hypertension in male mice, accompanied by glomerulopathy, interstitial fibrosis, and a trend towards increased albuminuria. Pressor effects were independent of plasma norepinephrine. Single-cell RNA sequencing of kidneys revealed most transcriptional changes in proximal tubule, thick ascending limb, and collecting duct, with enrichment of pathways in cholesterol synthesis, mitochondria respiration, ATP production, and transmembrane transporter activity. PFAS markedly increased the mRNA and protein of the pore-forming subunit of epithelial sodium channel (ENaC), with no change in {beta}ENaC and a slight reduction in {gamma}ENaC protein. Elevated ENaC coincided with a 30% decrease in Nedd4-2 phosphorylation (Ser448), suggesting reduced ENaC ubiquitination and degradation. However, protein expression of 1 Na+-K+-ATPase and serum- and glucocorticoid-regulated kinase 1 (SGK1) as well as SGK1 phosphorylation (Ser78) were unaltered. Amiloride abolished salt-induced hypertension in lower-dose mice but only partially corrected hypertension in the upper dose group. Taken together, our results provide causal evidence that PFAS exposure promotes hypertension, salt sensitivity, and kidney injury via renal epithelial mechanisms, supporting and extending human epidemiologic observations. Translational StatementOur findings establish four PFAS as causal drivers of salt-sensitive hypertension and kidney injury through convergent effects on ENaC and other tubular sodium transporters. These results not only provide a mechanistic explanation for epidemiologic associations but also identify PFAS as environmental amplifiers of dietary sodium risk. Given the ubiquity of human exposure, reducing PFAS burden alongside salt reduction may represent a complementary strategy to curb the global epidemic of hypertension and kidney disease.

physiology↗

bioRxiv2025

Deletion of RSK2 kinase alleviates age-dependent hypertension

BackgroundHypertension prevalence increases with age, reaching over 70% of people over age 65. The underlying mechanisms are poorly understood. This study interrogates a new signaling pathway in vascular smooth muscle of aged mice driven by p90 ribosomal S6 kinase, RSK2, and its role in increasing peripheral vascular resistance and blood pressure (BP). MethodsBasal BP measurements were taken at 26-29 month (812-892 day) old mice with global deletion of RSK2 (Rsk2-/-) prior to and following treatment with L-NAME. Cardiac function, vessel stiffness, myogenic responses, Ca2+events, contractility, immuno-staining, histology studies and western blotting were performed. ResultsResting BP and myogenic vasoconstriction were normal in aged global Rsk2-/- mice and elevated in wild type (WT) littermates. L-NAME treatment increased BP in aged Rsk2+/+ but not aged Rsk2-/-. Vessel stiffness and glycation collagen crosslinking increased in both aged Rsk2+/+ and Rsk2-/- compared to young vessels with no remodeling or increase in collagen content, even though BP in aged Rsk2-/- arterioles was normal. Increased vessel stiffness was dissociated from increased BP. Ca2+ transients increased and sensitivity to NO-induced relaxation decreased in aged Rsk2+/+ compared to young WT arterioles. IEL structures, eNOS and Hb distribution at myoendothelial junctions were disturbed impairing vasorelaxation in aged Rsk2+/+ but not aged Rsk2-/- arterioles. ConclusionsRSK2 plays a significant role in hypertension associated with aging by downregulating prorelaxant signaling and promoting procontractile events in the vasculature, offering potential new therapeutic targets.

physiology↗

bioRxiv2023

Direct extrusion of multifascicle prevascularized human skeletal muscle for volumetric muscle loss surgery

Volumetric skeletal muscle injuries are prevalent, highlighting the imperative need for scaffolds to facilitate the healing process of such wounds. Human skeletal muscle is composed of multiple fascicles, which are parallel bundles of muscle fibres surrounded by a layer of connective tissue that contains blood vessels and nerves. Replicating these structures presents a considerable challenge. Here, we developed a method to fabricate multifascicle human skeletal muscle scaffolds that mimic the natural structure of human skeletal muscle bundles using a seven-barrel nozzle. To form the core material to generate the fascicle structure, human skeletal myoblasts were encapsulated in Matrigel with calcium chloride. Meanwhile, to create the shell that plays a role as the connective tissue structure, human fibroblasts and human umbilical vein endothelial cells within a mixture of porcine muscle decellularized extracellular matrix and sodium alginate at a 95:5 ratio was used. We assessed four types of extruded scaffolds monolithic-monoculture (Mo-M), monolithic-coculture (Mo-C), multifascicle-monoculture (Mu-M), and multifascicle-coculture (Mu-C) to determine the structural effect of muscle mimicking scaffold. The Mu-C scaffold demonstrated cell proliferation, differentiation, vascularization, mechanical properties, and functionality that were superior to those of the other scaffolds. Furthermore, in an in vivo mouse model of volumetric muscle loss, the Mu-C scaffold effectively regenerated the tibialis anterior muscle defect, demonstrating its potential for volumetric muscle transplantation. The multibarrel nozzle device was applied to create functional Mu-C muscle scaffolds that structurally mimicked human skeletal muscle. Our nozzle will be further used to produce other volumetric functional tissues, such as tendons and peripheral nerves.

bioengineering↗

bioRxiv2022

Subcellular mapping of the protein landscape of SARS-CoV-2 infected cells for target-centric drug repurposing

The COVID-19 pandemic has resulted in millions of deaths and affected socioeconomic structure worldwide and the search for new antivirals and treatments are still ongoing. In the search for new drug target and to increase our understanding of the disease, we used large scale immunofluorescence to explore the host cell response to SARS-CoV-2 infection. Among the 602 host proteins studied in this host response screen, changes in abundance and subcellular localization were observed for 97 proteins, with 45 proteins showing increased abundance and 10 reduced abundances. 20 proteins displayed changed localization upon infection and an additional 22 proteins displayed altered abundance and localization, together contributing to diverse reshuffling of the host cell protein landscape. We then selected existing and approved small-molecule drugs (n =123) against our identified host response proteins and identified 3 compounds - elesclomol, crizotinib and rimcazole, that significantly reduced antiviral activity. Our study introduces a novel, targeted and systematic approach based on host protein profiling, to identify new targets for drug repurposing. The dataset of [~]75,000 immunofluorescence images from this study are published as a resource available for further studies.

cell biology↗

bioRxiv2022

Genetic mapping of multiple metabolic traits identifies novel genes for adiposity, lipids and insulin secretory capacity in outbred rats

Despite the successes of human genome-wide association studies, the causal genes underlying most metabolic traits remain unclear. We used outbred heterogeneous stock (HS) rats, coupled with expression data and mediation analysis, to identify quantitative trait loci (QTLs) and candidate gene mediators for adiposity, glucose tolerance, serum lipids and other metabolic traits. Physiological traits were measured in 1519 male HS rats, with liver and adipose transcriptomes measured in over 410 rats. Genotypes were imputed from low coverage whole genome sequence. Linear mixed models were used to detect physiological and expression QTLs (pQTLs and eQTLs, respectively), employing both SNP- and haplotype-based models for pQTL mapping. Genes with cis-eQTLs that overlapped pQTLs were assessed as causal candidates through mediation analysis. We identified 15 SNP-based pQTLs and 19 haplotype-based pQTLs, of which 11 were in common. Using mediation, we identified the following genes as candidate mediators of pQTLs: Grk5 for a fat pad weight pQTL on Chr1, Krtcap3 for fat pad weight and serum lipids pQTLs on Chr6, Ilrun for a fat pad weight pQTL on Chr20 and Rfx6 for a whole pancreatic insulin content pQTL on Chr20. Furthermore, we verified Grk5 and Ktrcap3 using gene knock-down/out models, thereby shedding light on novel regulators of obesity.

genetics↗

bioRxiv2021

PRE-CLINICAL IMMUNE RESPONSE AND SAFETY EVALUATION OF THE PROTEIN SUBUNIT VACCINE NANOCOVAX FOR COVID-19

The Coronavirus disease-2019 (COVID-19) pandemic caused by the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), has become a dire global health concern. The development of vaccines with high immunogenicity and safety is crucial for control of the global COVID-19 pandemic and prevention of further illness and fatalities. Here, we report development of SARS-CoV-2 vaccine candidate, Nanocovax, based on recombinant protein production of the extracellular (soluble) portion of the S protein of SARS-CoV-2. The results showed that Nanocovax induced high levels of S protein-specific IgG, as well neutralizing antibody in three animal models including Balb/C mice, Syrian hamsters, and non-human primate (Macaca leonina). In addition, the viral challenge study using the hamster model showed that Nanocovax protected the upper respiratory tract from SARS-CoV-2 infection. No adverse effects were induced by Nanocovax in swiss mice (Musmusculus var. Albino), Rats (Rattus norvegicus), and New Zealand rabbits. These pre-clinical results indicated that Nanocovax is safe and effective.

immunology↗

bioRxiv2021

The within-host evolutionary dynamics of seasonal and pandemic human influenza A viruses in young children

The evolution of influenza viruses is fundamentally shaped by within-host processes. However, the within-host evolutionary dynamics of influenza viruses remain incompletely understood, in part because most studies have focused on within-host virus diversity of infections in otherwise healthy adults based on single timepoint data. Here, we analysed the within-host evolution of 82 longitudinally-sampled individuals, mostly young children, infected with A/H3N2 or A/H1N1pdm09 viruses between 2007 and 2009. For A/H1N1pdm09 infections during the 2009 pandemic, nonsynonymous changes were common early in infection but decreased or remained constant throughout infection. For A/H3N2 viruses, early infection was dominated by purifying selection. However, as infections progressed, nonsynonymous variants increased in frequencies even though within-host virus titres decreased, leading to the maintenance of virus diversity via mutation-selection balance. Our findings suggest that this maintenance of genetic diversity in these children combined with their longer duration of infection may provide important opportunities for within-host virus evolution.

microbiology↗

bioRxiv2018

Trans-ethnic genome-wide association study provides insight into effector genes and molecular mechanisms for kidney function and highlights a causal effect on kidney-specific disease aetiologies

Chronic kidney disease (CKD) affects [~]10% of the global population, with considerable ethnic differences in prevalence and aetiology. We assembled genome-wide association studies (GWAS)1-3 of estimated glomerular filtration rate (eGFR), a measure of kidney function that defines CKD, in 312,468 individuals from four ancestry groups. We identified 93 loci (20 novel), which were delineated to 127 distinct association signals. These signals were homogenous across ancestries, and were enriched for protein-coding exons, kidney-specific histone modifications, and transcription factor binding sites for HDAC2 and EZH2. Fine-mapping revealed 40 high-confidence variants driving eGFR associations and highlighted potential causal genes with cell-type specific expression in glomerulus, and proximal and distal nephron. Mendelian randomisation (MR) supported causal effects of eGFR on overall and cause-specific CKD, kidney stone formation, diastolic blood pressure (DBP) and hypertension. These results define novel molecular mechanisms and effector genes for eGFR, offering insight into clinical outcomes and routes to CKD treatment development.

genetics↗