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Transplanted heart cardiomyocytes reveal continuous expression of antiapoptotic Bcl-2 protein
J Nozynski1, M Zakliczynski, E Zembala-Nozynska
1Department of Cardiac Surgery & Transplantation, Silesian Center for Heart Disease, Zabrze, Poland.
Background:
Apoptotic mechanisms take place in cardiocyte death during acute heart graft rejection and remodeling by the mitochondrial pathway. This process is suppressed by Bcl-2 protein. Besides that, knowledge about cardiocyte antiapoptotic responses after heart transplantation is scanty. We sought to estimate Bcl-2 expression in the absence of rejection.
Material:
The study group included endomyocardial biopsies taken at 1 week, 1 month, 1 through to 10 years after heart transplant, which showed rejection grade "0"; the control group were donor heart fragments.
Method:
Bcl-2 expression was determined immunohistochemically by NP030 antibody (DAKO) and Envision-DAB. The intensity of staining was assessed semiquantitatively.
Results:
No Bcl-2 expression was seen in the controls; in the posttransplant groups, the significantly strongest sarcoplasmic reaction was observed at 1 week after heart transplant. Thereafter, the reaction decreased, and was weakest in the 3- and 5-year groups. From this time, Bcl-2 expression increased albeit without statistical significance. The intensity of the reaction showed no correlation with the time elapsed from heart transplant (Spearman r = 0.05; P > .05).
Conclusion:
The expression of antiapoptotic Bcl-2 protein occurs during the entire posttransplant period, being probably a preservative and adaptative response.
Insights
Bcl-2 protein, crucial for preventing cardiocyte death, is expressed throughout the post-heart transplant period. Its expression is highest early after transplant and may serve a protective role.
Area of Science:
- Cardiology
- Immunology
- Cell Biology
Background:
- Cardiomyocyte apoptosis, mediated by the mitochondrial pathway, contributes to heart graft rejection and remodeling.
- The anti-apoptotic protein Bcl-2 plays a role in suppressing this process.
- Limited information exists on cardiomyocyte anti-apoptotic responses following heart transplantation.
Purpose of the Study:
- To investigate Bcl-2 expression in cardiomyocytes after heart transplantation in the absence of rejection.
- To understand the temporal pattern of Bcl-2 expression in the early and late post-transplant phases.
Main Methods:
- Endomyocardial biopsies were collected from heart transplant recipients with no rejection (grade 0) at various time points (1 week to 10 years) and from donor heart fragments (controls).
- Bcl-2 expression was quantified using immunohistochemistry with NP030 antibody and Envision-DAB, with semiquantitative assessment of staining intensity.
Main Results:
- No Bcl-2 expression was detected in control donor hearts.
- The strongest Bcl-2 sarcoplasmic staining in post-transplant hearts was observed at 1 week.
- Bcl-2 expression decreased by 3-5 years post-transplant, then gradually increased without statistical significance; no correlation with time post-transplant was found.
Conclusions:
- Antiapoptotic Bcl-2 protein expression is present throughout the entire post-heart transplant period.
- This sustained expression likely represents a crucial preservative and adaptive response in cardiomyocytes.
