T-cells help damaged mouse hearts

High blood pressure leads to cardiac damage and heart rhythm disorders (arrhythmias) and thereby can cause structural heart disease. The hormone angiotensin II plays a decisive role in this process. Besides its direct effect on the vascular system and the heart, angiotensin II also causes inflammation and can activate the immune system. Activated inflammatory cells, T lymphocytes, and macrophages, are all suspected of being involved in disease processes triggered by angiotensin II.

The team headed by Dr. Dominik Müller and Dr. Heda Kvakan from the “Experimental and Clinical Research Center” (ECRC) at the MDC and from the Helios Clinic in Berlin-Buch examined this issue. In their experiments with mice, the researchers suppressed the immune system by administering regulatory T cells. This recently discovered lymphocyte class is capable of maintaining the immune system in equilibrium. “As a result, the cardiac damage in the animals largely failed to occur, the development of fibrosis was avoided, and the generation of arrhythmias was suppressed,” explains Heda Kvakan.

The regulatory – or suppressor – T cells managed to bring the inflammatory cells under control. Thus, an excessive immune reaction generated by angiotensin II was suppressed and damage to the heart could be avoided. “These experiments have given us new insights into the role that the immune system plays in the development of cardiac damage through high blood pressure. However, experimental therapy with regulatory T cells is not new. Immunologist and cancer specialists have focused on regulatory T cells earlier. “We still do not know what side effects therapeutic suppression of the immune system by the regulatory T cells could have,” says Dominik Müller. “Thus, we cannot tell the patients to take a billion or so regulatory T cells and call me in the morning,” he adds. Effective therapies for high blood pressure already exist today. The future will show to what extent regulatory T cells could possibly be considered as a therapy. More important is the recognition that hypertension influences immunity and that the immune responses can be brought under control.