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Obesity may leave a long-lasting biological imprint on the immune system even after significant weight loss, according to a 10-year European study published in EMBO Reports.
Researchers led by Professor Claudio Mauro of the University of Birmingham found that helper T cells, or CD4+ lymphocytes, can retain molecular signs of previous obesity for years after body weight has been reduced.
The study focused on DNA methylation, a process in which chemical tags attach to DNA and can influence how cells function. The researchers found that obesity-related changes in immune cells may persist for five to 10 years after weight loss.
These changes were linked to biological processes involved in autophagy, which helps cells remove damaged material, and immune senescence, the gradual deterioration of immune function with age.
The findings may help explain why some health risks associated with obesity, including type 2 diabetes and certain cancers, can remain elevated after weight loss.
Researchers examined immune cells and fat tissue from several groups, including people receiving weight-loss treatment, individuals with Alström syndrome, exercise-study participants and patients undergoing joint replacement surgery. They also used high-fat-diet mouse models and samples from healthy volunteers.
Professor Mauro said sustained weight management may be needed for several years for the molecular effects of obesity to fade, although further research is required to determine how long the process takes.
The researchers said the findings could eventually lead to treatments aimed at reversing obesity-related immune changes alongside existing weight-loss therapies.
The study, titled “DNA methylation-mediated memory of obesity in CD4 T lymphocytes perpetuates immune dysregulation,” was published in EMBO Reports.
