This brain-immune system link could help treat heart attacks
What's the story
Researchers from the University of California, San Diego (UCSD) have identified a connection between the brain and immune system. The discovery, published in the journal Cell, could open new avenues for heart attack treatment. The study's lead author, UCSD neuroscientist Vineet Augustine, said disabling certain parts of this circuit resulted in significant improvements in mice suffering from induced heart attacks.
Nerve link
Vagus nerve's role in brain-immune system connection
The vagus nerve, a major bundle of fibers transmitting signals between the brain and other organs, has long intrigued researchers. It controls involuntary functions like breathing, blood pressure, and digestion. In 2000, scientists discovered that electrically stimulating this nerve in rats reduced production of an immune protein responsible for inflammation. This finding highlighted the potential link between cardiovascular health and the nervous and immune systems.
Stress impact
Stressful events trigger heart attacks
Stressful events have been linked to heart attacks. For instance, after the 1994 Northridge earthquake, sudden cardiac deaths in Los Angeles County rose more than fivefold. High-pressure sports events also lead to similar spikes. These instances show how stress can increase heart rate and potentially lead to heart problems over time due to harmful inflammation caused by fight-or-flight signals from the brain.
Study details
UCSD's research on brain-heart communication
The UCSD study employs advanced genetic and neuroscience tools to better understand the brain-heart communication and its role in heart attacks. Augustine found that during a heart attack in mice, certain vagal neurons (TRPV1 expressing neurons) "literally wrap around the injury site." This led his team to investigate whether blocking communication through these nerve cells could slow or prevent heart attacks in lab animals.
Experimental hurdles
Challenges and breakthroughs in the research
The experiments were technically challenging and required a lot of teamwork. One researcher performed heart surgery on the mice while others targeted specific cells in the brain, took physiological measurements, and also conducted echocardiography to image the heart in real time. Despite these challenges, Augustine's team saw significant improvements in pumping efficiency and electrical signals associated with heart contraction when they turned off this small group of TRPV1 nerve cells.
Neuron function
TRPV1 neurons and heart-brain-immune loop
The TRPV1 neurons transmit signals from the heart to the hypothalamus, a deep-brain structure that controls body temperature, thirst, hunger, and sleep. Other cells in the hypothalamus receive these signals and relay them to a different cluster of nerve cells projecting back to the heart. These then unleash an immune protein that drives inflammation. Blocking any of these three junctures in the heart-brain-immune loop relieved heart attack complications in mice.