While almost everyone knows that improved eating habits will most likely improve a range of health measures, researchers have warned that the effects that a poor diet have on the immune system can persist even after eating habits improve.
Writing in the Journal of Leukocyte Biology, the team behind the new study find that even after successful treatment of atherosclerosis - including lowering of blood cholesterol and a change in dietary habits - the effects of an unhealthy lifestyle still affect the way the immune system functions.
Led by Erik van Kampen from Leiden University in The Netherlands, the researchers used a mouse model to show that lasting changes in immune functions occurs largely because poor eating habits alter the way genes express themselves, including genes related to immunity.
These epigenetic changes in gene expression ultimately keep the risk of cardiovascular disorders higher than it would be had there been no exposure to unhealthy foods in the first place, said the team.
"We've long known that lifestyle and nutrition could affect immune system function," commented John Wherry, Ph.D., deputy editor of the Journal of Leukocyte Biology.
"The ability of nutritional history to have durable affects on immune cells demonstrated in this new report could have profound implications for treatment of diseases with immune underpinnings,” he said – adding that research to investigate the length of such effects will be ‘critical.’
"I hope that this study demonstrates the importance of diet-induced changes in the epigenome and encourages further research into the interaction between dietary patterns, DNA methylation and disease," added van Kampen.
The team analysed two groups of mice that had an altered gene making them more susceptible to developing high blood cholesterol and atherosclerosis. These mice were either fed a high-fat, high-cholesterol diet (Western-type diet, WTD) or a normal diet (chow).
After a long period of feeding, bone marrow was taken from the mice and transplanted into mice with a similar genetic background that had their own bone marrow destroyed. The recipient mice were left on chow diet for several months, after which the development of atherosclerosis in the heart was measured.
Van Kampen and his colleagues then examined the number and status of immune cells throughout the body in addition to analysing epigenetic markings on the DNA in the bone marrow.
They found that DNA methylation, an epigenetic signature, in the bone marrow was different in mice that received bone marrow from the Western-type-fed donors compared to the mice receiving bone marrow from chow-fed donors.
In addition, these mice had large differences in their immune system and increased atherosclerosis, said the team.
"We conclude that WTD challenge induces transplantable epigenetic changes in bone marrow, alterations in the hematopoietic system, and increased susceptibility to atherosclerosis,” concluded the team.
Source: Journal of Leukocyte Biology
Volume 96, Number 5, Pages 833-841, doi: 10.1189/jlb.1A0114-017R
“Diet-induced (epigenetic) changes in bone marrow augment atherosclerosis”
Authors: Erik van Kampen, et al