A new research has suggested that obesity resulting from a high-fat diet can trigger the immune system to increase inflammation and raise the risk of cardiovascular diseases that lead to heart attacks and stroke. The study – funded by the British Heart Foundation (BHF) and led by Queen Mary University of London (QMUL) in the United Kingdom – is published in the journal Cell Metabolism. Corresponding author Federica Marelli-Berg, a BHF professor of cardiovascular immunology at QMUL, says that their research reveals “a direct link between the food we eat, our weight, and dangerous inflammation which can cause heart disease.” The plaque comprises fatty substances, cholesterol, cellular waste, and other factors. As it builds up in the artery walls, the arteries harden and narrow, making it harder for blood to flow through them. If a blood clot forms in a diseased artery, it can impede blood flow and lead to a heart attack or stroke. The new study reveals a new link between obesity and heart disease risk that occurs via the triggering of an immune response involving a type of white blood cell called T cells. The researchers also conducted experiments in which they showed that mice fed on high-fat diets had higher levels of T cells than mice fed on normal diets. This, together with results from tests with different types of T cell, led them to conclude that a high-fat diet biases the development of T cells to produce more “inflammatory effector memory CD4+ T cells.” The team also found a cell signalling pathway that is key to the developmental bias, and showed that inactivating it corrects the bias. Prof Marelli-Berg says that drugs that target the pathway are already being tested as a cancer treatment and thus, “it might be possible to repurpose these drugs for the treatment of heart disease.” “This study shows that what we eat may also have an effect on our cardiovascular health via our immune system.” The researchers say that more studies now need to take the findings further – for example, to discover how long the harmful T cells persist at high levels in the blood. An important question to address is whether dieting can bring down the high levels of harmful T cells and reduce risk of heart disease, or whether once they reach a certain level they stay there, regardless of diet. Separately, another research has suggested that snow shovelling can increase the risk of heart attack. Researchers led by Dr Nathalie Auger, of the University of Montreal Hospital Research Centre in Montréal, examined data from two databases, gathering a total of 128,073 patient admissions and 68,155 MI-induced deaths that occurred in Quebec between 1981 and 2014. They analysed the data only in areas prone to heavy snowfalls, and they collected information during the winter months between November and April. Furthermore, the researchers received detailed weather information from Environment Canada for each of the regions studied, such as daily snowfall and temperature. Overall, Dr Auger and team found an association between heavy snowfall and a higher risk of both nonfatal and fatal MI. Specifically, heavy snowfall – defined as approximately 20 centimetres – correlated with a 16 percent relative increase in the chances of being admitted to the hospital due to an MI. Heavy snow was also associated with a 34 percent relative increase in the odds of dying from an MI in men. Approximately 60 percent of al MI-related hospital admissions and deaths were in men, but no adverse cardiovascular effects were noticed in women. The study also found that the probability of fatal MI increased proportionally with the consecutive number of snow days. The likelihood rose particularly in the day most close to the snowfall period, with a third of the MIs in men occurring the day following a snowfall. This association was even stronger for longer-lasting snowfalls – 2 to 3 days, for example.