Biology subjects

Muehlschlegel, J. D.

Publications and source records attributed to Muehlschlegel, J. D..

5 recordsLinked to original sources

bioRxiv2024

Sexual Dimorphism of Plasma and Tissue Proteomes in Human Calcific Aortic Valve Stenosis Pathogenesis

BACKGROUNDCalcific aortic valve stenosis (CAVS) is a global clinical burden, impacting around 2% of the population over 65 years of age. No pharmacotherapeutics exist, with surgical repair and transcatheter valve replacement being the only intervention. Females are underrepresented in studies of CAVS, leading to delay in timely intervention and increased mortality. Histopathology demonstrates female CAVS presents with decreased valvular calcification but increased fibrosis and severity of symptoms. We hypothesize that the underlying molecular mechanisms contributing to disease progression and fibrocalcific burden in AS differs between male and female patients. Our goal for this study is to use previously acquired proteomic datasets of a clinically-defined human AS cohort to examine sex disparities and underlying sex-specific disease signatures. METHODS and RESULTSAge-matched human AS tissue samples (n=4 females, n=14 males) were each segmented into non-diseased, fibrotic, and calcified disease stages and analyzed using LC-MS/MS proteomics and quantitative histopathology. CAVD plasma samples (n=20 females, n=30 males) were analyzed for circulating sex-specific biomarkers via LC-MS/MS. Unbiased principal component analysis shows sex- and stage-specific proteome clustering. AS pathogenesis drove sex-specific disparities in the valvular proteome: 338/1503 total proteins were differentially-enriched by sex across disease stages. Compared to sex-specific non-diseased controls, female fibrotic tissue resulted in 2.75-fold greater number of differentially-enriched proteins than did male fibrotic tissue (female: 42, male: 16; p<0.05 threshold). In contrast, female calcific tissue identified 2.473-fold less differentially-enriched proteins than male calcific tissue (female: 157, male 356; q<0.05 threshold). By Functional Enrichment Analysis revealed specific proteins responsible for the exacerbated valvular fibrosis signature in females, implicated adenosine phosphate metabolism as a potential male-specific driver of AS, and further reinforce the shared contribution of aberrant lipid and cholesterol activity to AS progression in both sexes. CONCLUSIONSWe reveal a sexually-dimorphic AS proteome, including the novel overabundance of ECM remodeling pathways in female calcified aortic valve tissues. This analysis allows for identification of potential sex-specific protein drug targets implicated in AS pathobiology.

pathology↗

bioRxiv2023

Intracellular Proteomics and Extracellular Vesiculomics as a Metric of Disease Recapitulation in 3D Bioprinted Aortic Valve Arrays

In calcific aortic valve disease (CAVD), mechanosensitive valvular cells respond to fibrosis- and calcification-induced tissue stiffening, further driving pathophysiology. No pharmacotherapeutics are available to treat CAVD, due to the lack of: 1) appropriate experimental models that recapitulate this complex environment; and 2) benchmarking novel engineered AV-model performance. We established a biomaterial-based CAVD model mimicking the biomechanics of the human AV disease-prone fibrosa layer, 3D-bioprinted into 96-well arrays. LC-MS/MS analyses probed the cellular proteome and vesiculome to compare the 3D-bioprinted model vs. traditional 2D monoculture, against human CAVD tissue. The 3D-bioprinted model highly recapitulated the CAVD cellular proteome (94% vs. 70% of 2D proteins). Integration of cellular/vesicular datasets identified known and novel proteins ubiquitous to AV calcification. This study explores how 2D vs. 3D-bioengineered systems recapitulate unique aspects of human disease, positions multi-omics as a novel technique for the evaluation of high throughput-based bioengineered model systems and potentiates future drug discovery.

bioengineering↗

bioRxiv2021

Distinct stress-dependent signatures of cellular and extracellular tRNA-derived small RNAs (tDRs)

The cellular response to stress is an important determinant of disease pathogenesis. Uncovering the molecular fingerprints of distinct stress responses may yield novel biomarkers for different diseases, and potentially identify key signaling pathways important for disease progression. tRNAs and tRNA-derived small RNAs (tDRs) comprise one of the most abundant RNA species in cells and have been associated with cellular stress responses. The presence of RNA modifications on tDRs has been an obstacle for accurately identifying tDRs with conventional small RNA sequencing. Here, we use AlkB-facilitated methylation sequencing (ARM-seq) to uncover a comprehensive landscape of cellular and extracellular tDR expression in a variety of human and rat cells during common stress responses, including nutritional deprivation, hypoxia, and oxidative stress. We found that extracellular tDRs have a distinct fragmentation signature with a predominant length of 31-33 nts and a highly specific termination position when compared with intracellular tDRs. Importantly, we found these signatures are better discriminators of different cellular stress responses compared to extracellular miRNAs. Distinct extracellular tDR signatures for each profiled stressor are elucidated in four different types of cells. This distinct extracellular tDR fragmentation pattern is also noted in plasma extracellular RNAs from patients on cardiopulmonary bypass. The observed overlap of these patient tDR signatures with the signatures of nutritional deprivation and oxidative stress in our cellular models provides preliminary in vivo corroboration of our findings and demonstrates the potential to establish novel extracellular tDR biomarkers in human disease models.

cell biology↗

bioRxiv2020

Conserved and Divergent Modulation of Calcification in Atherosclerosis and Aortic Valve Disease by Tissue Extracellular Vesicles

BackgroundFewer than 50% of patients develop calcification of both atherosclerotic plaques and aortic valves, implying differential pathogenesis. While circulating extracellular vesicles (EVs) act as biomarkers of cardiovascular diseases, tissue-entrapped EVs associate with early mineralization, but their contents, function, and contributions to disease remain unknown. ResultsGlobal proteomics of human carotid artery endarterectomies and calcified aortic valves from a total of 27 donors/patients revealed significant over-representation of proteins with vesicle-associated pathways/ontologies common to both diseases. We exploited enzymatic digestion, serial (ultra)centrifugation and OptiPrep density-gradient separation to isolate EV populations from diseased arteries and valves. Mass spectrometry found 22 EV marker proteins to be highly enriched in the four least-dense OptiPrep fractions while extracellular matrix proteins predominated in denser fractions, as confirmed by CD63 immunogold electron microscopy and nanoparticle tracking analysis. Proteomics and miRNA-sequencing of OptiPrep-enriched tissue EVs quantified 1,104 proteins and 123 miR cargoes linked to 5,182 target genes. Pathway networks of proteins and miR targets common to artery and valve tissue EVs revealed a shared regulation of Rho GTPase and MAPK intracellular signaling cascades. 179 proteins and 5 miRs were significantly altered between artery and valve EVs; multi-omics integration determined that EVs differentially modulated cellular contraction and p53-mediated transcriptional regulation in diseased vascular vs. valvular tissue. ConclusionsOur findings delineate a strategy to isolate, purify, and study protein and RNA cargoes from EVs entrapped in fibrocalcific tissues. Multi-omics and network approaches implicated tissue-resident EVs in human cardiovascular disease.

systems biology↗

bioRxiv2018

Sex differences in gene expression in response to ischemia in the human myocardium

Abstract and KeywordsO_ST_ABSBackgroundC_ST_ABSSex differences exist in the prevalence, presentation, and outcomes of ischemic heart disease. Females have higher risk of heart failure post myocardial infarction relative to males and the female sex is an independent risk factor for hospital and operative mortality after cardiac surgery. However, the mechanisms underlying this sexual dimorphism remain unclear. We examined sex differences in human myocardial gene expression in response to ischemia.\n\nMethodsLeft ventricular biopsies from 68 male and 46 female patients undergoing aortic valve replacement surgery were obtained at baseline and after a median 74 minutes of cold cardioplegic arrest/ischemia and respective transcriptomes were quantified by RNA-Seq. Sex-specific responses to ischemia were quantified by differential gene expression, expression quantitative trait loci (eQTL) and pathway and functional analysis. Cell-type enrichment analysis. was used to obtain an estimate of the identity and relative proportions of different cell types present in each sample.\n\nResultsA sex-specific response to ischemia was observed for 271 genes. Functional annotation analysis revealed sex-specific modulation of the oxytocin signaling pathway and common pathway of fibrin clot formation. The eQTL analysis identified variant-by-sex interaction eQTLs at baseline and post-ischemia, indicative of sex differences in the genotypic effects on gene expression, and cell-type enrichment analysis showed sex-bias in proportion of specific cell types.\n\nConclusionIn response to myocardial ischemia, the human left ventricle demonstrates changes in gene expression that differ between the sexes. These differences provide insight into the sexual dimorphism of ischemic heart disease and may aid in the development of sex-specific therapies that reduce myocardial injury.

genomics↗