Circulating levels of the cardiac hormone brain natriuretic peptide in heart transplant patients may increase before and during an acute rejection episode. A similar increase in atrial natriuretic factor does not occur. This article reviews the possible significance of these findings.
During acute cardiac allograft rejection episodes, brain natriuretic peptide plasma levels may increase well above baseline values. This increase is not the result of hemodynamic changes because brain natriuretic peptide levels during International Society for Heart and Lung Transplantation grade 3 rejection do not correlate with various hemodynamic parameters, and atrial natriuretic factor levels are not affected. Similar results were observed in experimentally induced autoimmune myocarditis. In-vitro data showed that some proinflammatory cytokines and chemokines are capable of selectively increasing brain natriuretic peptide gene expression and secretion in cardiocyte cultures.
Atrial natriuretic factor and brain natriuretic peptide are usually co-regulated. Findings in heart allograft recipients, in experimentally induced myocarditis, and in vitro suggest that, unlike atrial natriuretic factor, brain natriuretic peptide is uniquely related to inflammation. These findings may translate into biomarkers or therapies for cardiac allograft rejection or myocarditis and may explain the existence of two hormones with nearly identical biologic properties.