High-Fat Diets Linked to Impaired Infection Response

High-fat diets may impact heart health, metabolism, and weight, influencing long-term wellness and disease risk.

A new study in The Journal of Immunology highlights how a high-fat diet may weaken the immune system’s response to infections by affecting neutrophil function. Researchers found that obese male mice on a high-fat diet had increased neutrophil numbers, but these cells displayed markers of immaturity or aging and were less effective at killing bacteria (1^✔ ✔Trusted Source
High fat diet feeding impairs neutrophil phagocytosis, bacterial killing, and neutrophil-induced hematopoietic regeneration

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The prevalence of obesity in American adults is 40.3%. In recent years, obesity has come to be associated with chronic, low-grade inflammation, which contributes to obesity-related diseases, including increased susceptibility to infection.

Exploring Neutrophil Dysfunction in Obesity

The link between chronic inflammation and increased infections emphasizes the need to uncover the impact of obesity on immune cells such as neutrophils. “We hope that by understanding how neutrophil function is altered with exposure to high fat diet, we can take future steps to restore function and improve patient health outcomes,” shared Dr. Kanakadurga Singer, Associate Professor for Departments of Pediatrics and Molecular & Integrative Physiology at the University of Michigan Medical School, who led the study.

“We hope this study lets investigators and clinicians know that although neutrophils may be increased in number in individuals with elevated BMI or diet-induced obesity, these neutrophils may not be functional,” said Dr. Singer.

In this study, male mice were fed a normal diet or HFD in a model known to induce obesity. Neutrophils were isolated from the blood and bone marrow and compared between the two diet groups. Researchers found that HFD impaired bone marrow neutrophil’s ability to store and release TNF-alpha, an immune signal important for regulating inflammation. Neutrophils from HFD mice expressed different genes involved in fat storage and metabolism than normal diet mice. When neutrophils were exposed to Pseudomonas aeruginosa, a bacterium that can cause pneumonia, HFD-fed neutrophils were found to have a reduced capacity to ingest and kill bacteria. Altogether, these results indicate that diet-induced obesity can have a range of impacts on immune cells, affecting their ability to properly function.

“We hope to build on these findings by uncovering what is causing the impairment of neutrophils exposed to HFD. My team plans to conduct further studies on why these neutrophils are defective, especially in their bacterial killing function, and if these neutrophils are impaired in killing specific types of bacteria or a wide range. Hopefully, we can identify other implications of neutrophil dysfunction due to HFD and if there are ways to improve this impaired function,” shared Dr. Singer.

Reference:

1. High fat diet feeding impairs neutrophil phagocytosis, bacterial killing, and neutrophil-induced hematopoietic regeneration – (https://academic.oup.com/jimmunol/advance-article/doi/10.1093/jimmun/vkaf024/8081674)

Source-Eurekalert