Transcriptomic signature of Human Cardiac Fibroblast in Hypertrophic Obstructive Cardiomyopathy
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Background
Hypertrophic Cardiomyopathy (HCM) is a cardiac disorder characterized by an increased interstitial fibrosis and Extracellular Matrix (ECM) remodeling. Cardiac fibroblasts (CFs) have a crucial role in ECM remodeling as well as influencing contractility. There is accumulating evidence that the phenotype of CFs is disease-specific. Here, we investigate the transcriptome signature of CFs in Hypertrophic obstructive Cardiomyopathy (HOCM) patients and its functional significance.
Methods
Primary CFs were isolated from myectomy specimens of 12 clinically phenotyped HOCM patients and 3 controls. RNA libraries were prepared from cell isolates for whole transcriptome sequencing. Differential expression analysis was conducted using the Tuxedo pipeline. Pathway and Gene Ontology (GO) enrichment were performed using Protein-protein interaction network analysis and functional clustering were performed using Cytoscape StringApp. Expression of candidate genes and proteins was validated using quantitative PCR, Immunocytochemistry, immunohistochemistry, cytokines/chemokines profiling and western blotting, in patient-derived CFs extracts, CFs-conditioned media, and myocardial tissue sections.
Results
Whole transcriptome analysis identified 265 significant differentially expressed genes (DEGs) in HOCM fibroblasts compared to controls. The most significant GO terms identified were associated with ECM organization and inflammatory response. The most significant GO terms identified were associated with ECM organization and inflammatory response, with circos plot analysis further highlighting pathway-specific gene overlap within inflammatory and structural signaling clusters. The DEGs encompassed gene families such as collagens, proteases, fibulins, inflammatory cytokines, integrins and signaling receptors and kinases. MYC was upregulated alongside chemokine ligands and receptors, highlighting a MYC-linked chemokine signaling axis within the inflammatory HOCM-CFs phenotype. The protein expression of selected ‘extracellular Matrix organization’ and ‘inflammatory response’ genes confirmed the transcriptome results.
Conclusion
Transcriptomic profiling of patient-derived HOCM-CFs identified genes and pathways associated with inflammatory signaling, ECM remodeling, and altered cell–cell/matrix communication. These findings show that advanced HOCM-CFs acquire an inflammatory-remodeling phenotype, with ECM genes other than collagens.
Novelty and Significance
What Is Known?
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Hypertrophic cardiomyopathy is characterized by myocardial hypertrophy, interstitial fibrosis, extracellular matrix remodelling, and inflammatory signalling.
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Most human HCM transcriptomic studies have been performed using whole myocardial tissue, which limits resolution of fibroblast-specific disease programmes.
What New Information Does This Article Contribute?
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Patient-derived cardiac fibroblasts from patients with advanced hypertrophic obstructive cardiomyopathy exhibit a distinct transcriptomic signature enriched for inflammatory signalling, extracellular matrix organization, chemokine activity, and altered cell–matrix communication.
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The HOCM-CF signature is not characterized by uniform collagen gene induction, but by selective ECM remodelling involving fibulins, proteases, integrins, matricellular genes, and downregulation of selected collagen-associated matrix components.
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Comparison with bulk myocardial RNA-sequencing and publicly available human cardiomyopathy data supports the biological relevance of the fibroblast-derived signature while highlighting the limited sensitivity of bulk tissue transcriptomics for resolving fibroblast-specific programmes.
What Is the Significance?
This study identifies a disease-associated inflammatory and ECM-remodelling state in patient-derived HOCM cardiac fibroblasts. The findings extend the role of cardiac fibroblasts in HOCM beyond classical collagen deposition and suggest that fibroblast-mediated matrix remodelling, cytokine/chemokine signalling, and altered cell–matrix communication may contribute to myocardial remodelling in advanced obstructive disease. These data support the value of fibroblast-focused profiling for uncovering disease-relevant mechanisms that may be masked in whole myocardial tissue analyses and provide candidate pathways for future mechanistic and therapeutic studies.
