The high fat, high calorie, and low fiber diet commonly referred to as the “Western diet” has long been associated with the increased rate of diseases like atherosclerosis and diabetes. Now, scientists from the University of Bonn demonstrate how the Western diet makes the immune system “more aggressive.”
The same long-lasting inflammation that connects the Western diet with the development of various metabolic diseases stems from the immune system’s response to excess fat and calories. In their new Cell study, researchers show how the immune reaction resembles that of the reaction to a bacterial infection.
First, researchers looked at the inflammatory responses of mice fed the Western diet. They saw a strong response, similar to the way the immune system would respond to a bacterial infection. For example, they saw an enhanced influx of immune cells like granulocytes and monocytes.
Next, they examined isolated bone marrow immune progenitor cells, comparing those collected from mice fed either the Western diet or a healthy control diet.
"Genomic studies did, in fact, show that the Western diet had activated a large number of genes in the progenitor cells,” explained Dr. Joachim Schultze. “The genes affected included those responsible for proliferation and maturation.”
Researchers also found that a month-long regimen of the healthy control diet following the Western diet reversed the inflammation but not the “genetic reprogramming of the immune cells and their precursors.” Does the innate immune system, thought to be the non-specific arm of immunity - have memory after all?
"The immune system consequently reacts even to small stimuli with stronger inflammatory responses,” explained Dr. Eicke Latz.
In many progenitor cell samples, researchers saw evidence of “training” in the innate immune system as a result of the Western diet. This includes genetic activity of the NLRP3 inflammasome, an intracellular signaling complex in the body typically responsible for producing inflammatory markers in response to pathogens.
"The foundations of a healthy diet need to become a much more prominent part of education than they are at present,” Latz said. “Only in this way can we immunize children at an early stage against the temptations of the food industry.”
Source: University of Bonn