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Updated: Jul 22, 2026
Orthotopic Aortic Transplantation: A Rat Model to Study the Development of Chronic Vasculopathy
Published on: December 4, 2010
Endothelial PTBP1 Deletion in Transplanted Cardiac Tissue Limits Cardiac Allograft Vasculopathy
Christopher L Pathoulas1, Koki Hayashi2,3, Ivy Rosales2,3
1University of Connecticut Health Center, Center for Vascular Biology, Farmington CT.
Insights
PTBP1 is a key regulator in chronic cardiac allograft rejection. Targeting endothelial PTBP1 may reduce graft injury and immune suppression in heart transplant patients.
Area of Science:
- Immunology
- Cardiovascular Biology
- Molecular Biology
Background:
- Cardiac allograft vasculopathy (CAV) is a major cause of heart transplant failure.
- Endothelial cell dysfunction is central to CAV development, but underlying mechanisms are unclear.
- Limited therapeutic options exist for CAV, necessitating novel treatment strategies.
Purpose of the Study:
- To investigate molecular mechanisms of endothelial dysfunction in CAV.
- To identify key regulators of endothelial inflammatory responses in chronic heart transplant rejection.
- To assess the therapeutic potential of targeting PTBP1 in CAV.
Main Methods:
- Utilized inCITE-seq to profile endothelial gene and protein expression in human cardiac tissues from CAV and control groups.
- Examined nuclear PTBP1 protein levels and TGF-β signaling in CAV endothelium.
- Assessed the functional role of PTBP1 by endothelial-specific gene deletion in a murine model of CAV.
Main Results:
- CAV endothelium showed increased TGF-β signaling and reduced oxidative phosphorylation.
- Elevated nuclear PTBP1 levels correlated with TGF-β pathways and cardiac dysfunction.
- Endothelial-specific Ptbp1 deletion reduced CAV hallmarks and preserved mitochondrial function in mice.
Conclusions:
- PTBP1 is identified as a critical endothelial regulator in chronic cardiac allograft rejection.
- PTBP1 links fibrotic stress, mitochondrial dysfunction, and immune activation in CAV.
- Targeting endothelial PTBP1 offers a potential strategy to mitigate chronic graft injury.
Background:
Cardiac allograft vasculopathy (CAV) is a leading cause of late graft failure and mortality following heart transplantation, with limited therapeutic options. Endothelial cells (ECs), at the interface between the donor graft and host immune system, play a central role in CAV development. However, the molecular mechanisms driving endothelial dysfunction and vascular remodeling in chronic heart transplant rejection remain poorly understood.
Methods:
To characterize endothelial alterations associated with CAV, we isolated nuclei from cardiac tissues of four human donor groups: (1) early post-transplant CAV-negative surveillance biopsies, (2) CAV-negative explanted grafts with acute cellular rejection (ACR), (3) late-stage CAV-positive explanted grafts, and (4) naïve non-transplanted control hearts. We applied intranuclear cellular indexing of transcriptomes and epitopes (inCITE-seq) to profile endothelial gene expression together with nuclear protein levels of splice factor polypyrimidine tract-binding protein 1 (PTBP1), a key post-transcriptional regulator of endothelial inflammatory responses. Functional relevance of PTBP1 was assessed using endothelial-specific deletion of Ptbp1 in an F1 hybrid murine model of CAV.
Results:
In human CAV, endothelial cells exhibited increased transforming growth factor-β (TGF-β) signaling and reduced oxidative phosphorylation (OxPhos) transcripts. Nuclear PTBP1 protein levels were markedly elevated in CAV endothelium and were associated with TGF-β-responsive transcriptional programs and correlated with clinical indices of cardiac dysfunction. In murine heart transplants, endothelial-specific deletion of Ptbp1 markedly reduced hallmarks of CAV, including neointimal hyperplasia, fibrosis, and lymphocyte activation. At the molecular level, endothelial Ptbp1 deletion prevented suppression of mitochondrial transcripts and preserved mitochondrial content and integrity under hypoxic stress, attenuating interferon signaling in endothelial cells.
Conclusion:
These findings identify PTBP1 as a central endothelial regulator linking pro-fibrotic stress to mitochondrial dysfunction and immune activation in chronic cardiac allograft rejection. Targeting endothelial PTBP1 may represent a strategy to limit chronic graft injury while minimizing systemic immunosuppression.
