Hypertrophic Cardiomyopathy (HCM) is a common inherited disorder characterized by unexplained left ventricular hypertrophy with or without left ventricular outflow tract (LVOT) obstruction. Single-nuclei RNA-sequencing (snRNA-seq) of both obstructive and nonobstructive HCM patient samples has revealed alterations in communication between various cell types, but no direct and integrated comparison between the two HCM phenotypes has been reported. We performed a bioinformatic analysis of HCM snRNA-seq datasets from obstructive and nonobstructive patient samples to identify differentially expressed genes and distinctive patterns of intercellular communication. Differential gene expression analysis revealed 37 differentially expressed genes, predominantly in cardiomyocytes but also in other cell types, relevant to aging, muscle contraction, cell motility, and the extracellular matrix. Intercellular communication was generally reduced in HCM, affecting the extracellular matrix, growth factor binding, integrin binding, PDGF binding, and SMAD binding, but with increases in adenylate cyclase binding, calcium channel inhibitor activity, and serine-threonine kinase activity in nonobstructive HCM. Increases in neuron to leukocyte and dendritic cell communication, in fibroblast to leukocyte and dendritic cell communication, and in endothelial cell communication to other cell types, largely through changes in the expression of integrin-β1 and its cognate ligands, were also noted. These findings indicate both common and distinct physiological mechanisms affecting the pathogenesis of obstructive and nonobstructive HCM and provide opportunities for the personalized management of different HCM phenotypes.
more »
« less
Altered intercellular communication and extracellular matrix signaling as a potential disease mechanism in human hypertrophic cardiomyopathy
Abstract Hypertrophic cardiomyopathy (HCM) is considered a primary disorder of the sarcomere resulting in unexplained left ventricular hypertrophy but the paradoxical association of nonmyocyte phenotypes such as fibrosis, mitral valve anomalies and microvascular occlusion is unexplained. To understand the interplay between cardiomyocyte and nonmyocyte cell types in human HCM, single nuclei RNA-sequencing was performed on myectomy specimens from HCM patients with left ventricular outflow tract obstruction and control samples from donor hearts free of cardiovascular disease. Clustering analysis based on gene expression patterns identified a total of 34 distinct cell populations, which were classified into 10 different cell types based on marker gene expression. Differential gene expression analysis comparing HCM to Normal datasets revealed differences in sarcomere and extracellular matrix gene expression. Analysis of expressed ligand-receptor pairs across multiple cell types indicated profound alteration in HCM intercellular communication, particularly between cardiomyocytes and fibroblasts, fibroblasts and lymphocytes and involving integrin β1 and its multiple extracellular matrix (ECM) cognate ligands. These findings provide a paradigm for how sarcomere dysfunction is associated with reduced cardiomyocyte secretion of ECM ligands, altered fibroblast ligand-receptor interactions with other cell types and increased fibroblast to lymphocyte signaling, which can further alter the ECM composition and promote nonmyocyte phenotypes.
more »
« less
- Award ID(s):
- 2018149
- NSF-PAR ID:
- 10377296
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
Abstract The anti‐malaria drug artesunate and other chemical analogs of artemisinin have demonstrated cytostatic and cytotoxic effects in bacterial and cancer cells. Artemisinin‐derived compounds have also been demonstrated to attenuate fibrosis in preclinical animal models, but the mechanisms by which this inhibition occurs are not well‐understood. We investigated the effects of artesunate on the emergence of the myofibroblast, which is causally implicated in pro‐fibrotic pathologies. CRL‐2097 human dermal fibroblasts were analyzed for protein and transcript expression after treatment with artesunate to analyze fibroblast activation. Proliferation and apoptosis were also evaluated following treatment with artesunate in this cell line. Treatment of human dermal fibroblasts with artesunate antagonized fibroblast activation and pro‐fibrotic extracellular matrix (ECM) deposition, both at basal culture conditions and when cultured in the presence of exogenous transforming growth factor‐β1 (TGF‐β1), a major pro‐fibrotic cytokine. Artesunate‐treated fibroblasts also demonstrated decreased proliferation and increased apoptosis. Transcript analysis by quantitative real‐time polymerase chain reaction demonstrated that artesunate downregulated expression of pro‐fibrotic genes including canonical myofibroblast markers, ECM genes, and several TGF‐β receptors and ligands, and upregulated expression of cell cycle inhibitors and matrix‐metalloproteinases. Together, these data demonstrate that artesunate antagonizes fibroblast activation and decreases expression of pro‐fibrotic genes, while also promoting myofibroblast apoptosis, suggesting that these mechanisms may be responsible in part for the anti‐fibrotic effects of artesunate described previously.
-
more » « less
Objective Subglottic stenosis (SGS) may result from prolonged intubation where fibrotic scar tissue narrows the airway. The scar forms by differentiated myofibroblasts secreting excessive extracellular matrix (ECM). TGF‐β1 is widely accepted as a regulator of fibrosis; however, it is unclear how biomechanical pathways co‐regulate fibrosis. Therefore, we phenotyped fibroblasts from pediatric patients with SGS to explore how key signaling pathways, TGF‐β and Hippo, impact scarring and assess the impact of inhibiting these pathways with potential therapeutic small molecules SB525334 and DRD1 agonist dihydrexidine hydrochloride (DHX).
Methods Laryngeal fibroblasts isolated from subglottic as well as distal control biopsies of patients with evolving and maturing subglottic stenosis were assessed by α‐smooth muscle actin immunostaining and gene expression for α‐SMA, FN, HGF, and CTGF markers. TGF‐β and Hippo signaling pathways were modulated during TGF‐β1‐induced fibrosis using the inhibitor SB525334 or DHX and analyzed by RT‐qPCR for differential gene expression and atomic force microscopy for ECM stiffness.
Results SGS fibroblasts exhibited higher α‐SMA staining and greater inflammatory cytokine and fibrotic marker expression upon TGF‐β1 stimulation (
p < 0.05). SB525334 restored levels to baseline by reducing SMAD2/3 nuclear translocation (p < 0.0001) and pro‐fibrotic gene expression (p < 0.05). ECM stiffness of stenotic fibroblasts was greater than healthy fibroblasts and was restored to baseline by Hippo pathway modulation using SB525334 and DHX (p < 0.01).Conclusion We demonstrate that distinct fibroblast phenotypes from diseased and healthy regions of pediatric SGS patients respond differently to TGF‐β1 stimulation, and SB525334 has the superior potential for subglottic stenosis treatment by simultaneously modulating TGF‐β and Hippo signaling pathways.
Level of Evidence NA
Laryngoscope , 134:287–296, 2024 -
null (Ed.)Background: Hypertrophic cardiomyopathy (HCM) is caused by pathogenic variants in sarcomere protein genes that evoke hypercontractility, poor relaxation, and increased energy consumption by the heart and increased patient risks for arrhythmias and heart failure. Recent studies show that pathogenic missense variants in myosin, the molecular motor of the sarcomere, are clustered in residues that participate in dynamic conformational states of sarcomere proteins. We hypothesized that these conformations are essential to adapt contractile output for energy conservation and that pathophysiology of HCM results from destabilization of these conformations. Methods: We assayed myosin ATP binding to define the proportion of myosins in the super relaxed state (SRX) conformation or the disordered relaxed state (DRX) conformation in healthy rodent and human hearts, at baseline and in response to reduced hemodynamic demands of hibernation or pathogenic HCM variants. To determine the relationships between myosin conformations, sarcomere function, and cell biology, we assessed contractility, relaxation, and cardiomyocyte morphology and metabolism, with and without an allosteric modulator of myosin ATPase activity. We then tested whether the positions of myosin variants of unknown clinical significance that were identified in patients with HCM, predicted functional consequences and associations with heart failure and arrhythmias. Results: Myosins undergo physiological shifts between the SRX conformation that maximizes energy conservation and the DRX conformation that enables cross-bridge formation with greater ATP consumption. Systemic hemodynamic requirements, pharmacological modulators of myosin, and pathogenic myosin missense mutations influenced the proportions of these conformations. Hibernation increased the proportion of myosins in the SRX conformation, whereas pathogenic variants destabilized these and increased the proportion of myosins in the DRX conformation, which enhanced cardiomyocyte contractility, but impaired relaxation and evoked hypertrophic remodeling with increased energetic stress. Using structural locations to stratify variants of unknown clinical significance, we showed that the variants that destabilized myosin conformations were associated with higher rates of heart failure and arrhythmias in patients with HCM. Conclusions: Myosin conformations establish work-energy equipoise that is essential for life-long cellular homeostasis and heart function. Destabilization of myosin energy-conserving states promotes contractile abnormalities, morphological and metabolic remodeling, and adverse clinical outcomes in patients with HCM. Therapeutic restabilization corrects cellular contractile and metabolic phenotypes and may limit these adverse clinical outcomes in patients with HCM.more » « less
-
null (Ed.)Background and objectives Previous work has identified that gene expression differences in cell adhesion pathways exist between humans and chimpanzees. Here, we used a comparative cell biology approach to assay interspecies differences in cell adhesion phenotypes in order to better understand the basic biological differences between species’ epithelial cells that may underly the organism-level differences we see in wound healing and cancer. Methodology We used skin fibroblast cell lines from humans and chimpanzees to assay cell adhesion and migration. We then utilized published RNA-Seq data from the same cell lines exposed to a cancer / wound-healing mimic to determine what gene expression changes may be corresponding to altered cellular adhesion dynamics between species. Results The functional adhesion and migration assays revealed that chimpanzee fibroblasts adhered sooner and remained adherent for significantly longer and move into a “wound” at faster rate than human fibroblasts. The gene expression data suggest that the enhanced adhesive properties of chimpanzee fibroblasts may be due to chimpanzee fibroblasts exhibiting significantly higher expression of cell and focal adhesion molecule genes than human cells, both during a wound healing assay and at rest. Conclusions and implications Chimpanzee fibroblasts exhibit stronger adhesion and greater cell migration than human fibroblasts. This may be due to divergent gene expression of focal adhesion and cell adhesion molecules, such as integrins, laminins, and cadherins, as well as ECM proteins like collagens. This is one of few studies demonstrating that these divergences in gene expression between closely related species can manifest in fundamental differences in cell biology. Our results provide better insight into species-specific cell biology phenotypes and how they may influence more complex traits, such as cancer metastasis and wound healing.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41598-022-08561-x
