High-fat diet weakens immune response in obesity

A new study published in The Journal of Immunology reveals that a high-fat diet can harm the immune system, especially the function of neutrophils. Neutrophils are essential immune cells that quickly respond to infections caused by bacteria or viruses. In this study, researchers fed male mice a high-fat diet to induce obesity. They found that while the number of neutrophils increased, these cells were often immature or showed signs of aging. Importantly, the neutrophils from these mice struggled to kill bacteria effectively. Obesity affects a significant portion of American adults, with a prevalence rate of 40.3%. It is typically caused by consuming more calories than the body uses, especially from high-fat and sugar-rich foods. Recent research links obesity to chronic inflammation, which can lead to various health issues, including a greater risk of infections. Dr. Kanakadurga Singer, the lead researcher, highlights the need to understand how high-fat diets alter neutrophil function. She hopes this knowledge will help restore neutrophil efficiency and improve health outcomes for patients with obesity. In the study, neutrophils were collected from mice on a normal diet compared to those on a high-fat diet. Researchers found that the high-fat diet affected neutrophils' ability to manage a vital immune signal called TNF-alpha, which is important for controlling inflammation. When tested with the bacteria Pseudomonas aeruginosa, neutrophils from high-fat diet mice were less capable of ingesting and killing the bacteria. The findings suggest that a diet high in fat significantly impacts the immune system's functioning. Dr. Singer plans to conduct further research to identify the exact reasons behind the neutrophil impairment and explore potential solutions to enhance their function in individuals affected by obesity.