High Blood Lipid Levels Found To Be Protective Against Allergens

People who have blood lipid levels that are relatively high are less prone to suffer from allergic diseases like eczema and asthma. These lipids reduce the activity of genes that are crucial for allergic reactions. An article describing this was written by researchers at the Leiden University Medical Center (LUMC) and published in Nature Communications.

“We already knew that lipids in our blood, such as triglycerides and cholesterol, can influence the behaviour of immune cells,” says Professor of Biomedical Data Sciences Bas Heijmans. “We have now shown that these lipids dampen the activity of genes that play a key role in allergies.” As a result, allergic reactions are less likely to occur.

The first step taken by the researchers was mapping the genes present in over 3,200 people’s immune cells. “This turned out to be more than 17,000 genes,” says Koen Dekkers, the first author of the study. “Then, step by step, we figured out exactly which genes are affected by lipids in the blood, leading us to a group of genes that trigger allergic reactions.”

The researchers were able to demonstrate that this association is causal by integrating the blood levels of lipids, gene activity, and known genetic variations between individuals using a state-of-the-art analysis tool.

An allergic reaction is the immune system’s overreaction to an innocuous chemical. Consider how pollen might create hay fever as an example. The scientists discovered that basophils’ active genes are primarily impacted by lipids. These immune cells are essential in starting an allergic reaction because they produce histamine among other things.

Saturated vs Unsaturated

The researchers found that these basophils are particularly sensitive to triglycerides. Our DNA plays a role in blood triglyceride levels, but our diet plays a larger role.  “And that is very interesting, of course,” says Heijmans. “This could mean that patients with severe allergic reactions might benefit from extra triglycerides, or more precisely, the fatty acids that make up triglycerides.”

However, we are not yet there, Heijmans expounds. “We first need to test whether and, if so, which fatty acids actually have these beneficial effects. Is it mainly the healthy, unsaturated fatty acids? That would be good news. Or perhaps the unhealthy, saturated fatty acids?” Furthermore, it is yet unclear how lipids affect immune cells in this way.

Unexpected Outcome

Heijmans and Dekkers weren’t exactly experts in allergies.  “We did not expect at all that this study would point us in that direction,” says Dekkers. They had set their eyes on cardiovascular diseases, in collaboration with Professor of Cardiology Wouter Jukema. “These diseases are driven by the interaction between fats and the immune system,” says Heijmans.

“We expected to discover how lipids affect genes involved in cardiovascular disease. But the effect on allergic reactions was much stronger.” Their research had an unexpected outcome, but that hasn’t dampened their enthusiasm. “Such a surprising discovery is like icing on the cake for a scientist,” says Heijmans.

Will they now shift their focus to researching allergies? Dekkers, who is currently employed by Uppsala University in Sweden, does not completely rule it out. “I definitely see follow-up research in it, and it could just be that I pick this up again later,” Heijmans says, “Wouter Jukema and I are as interested as ever in the effect of fats on immune cells, but are now focusing again on their role in cardiovascular disease.”

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