Epigenetics – the study of changes in organisms caused by modification of gene expression rather than alteration in the genetic code itself– has gained much attention in recent years. Environmental factors including diet, smoking and stress have been shown to impact gene expression through epigenetic mechanisms.
In a recent experiment involving the collaboration of several medical institutions, an experiment was performed on mice to determine how their immunity responded to a typical Western diet. When mice were fed a Western diet, systemic inflammation occurred which was entirely expected. However, what was particularly interesting was that the Western (inflammatory) diet fundamentally changed their immune system. After eating high calorie, low nutrient food, not only did the mice exhibit more systemic inflammation (not surprising), but their white blood cells became programmed to remain hyper-sensitive to inflammatory triggers. The cellular “memory” had changed.
Here is how it worked: a gene called NLRP3 (for Nucleotide binding domain Like Receptor Protein) makes a protein that is used by our immune cells to recognize harmful bacteria and viruses. This protein made by the NLRP3 gene recognizes “bad” cell remnants. These can be parts of bacterial cell membranes, or pieces of genetic material found in viruses, or even parts of a cell that are supposed to be contained but may leak out due to cellular trauma. It is a fundamental way our immune cells recognize something is wrong – bacteria are present or acute tissue damage occurred, for example – and thus launch an inflammatory response to deal with the biological crisis and take care of it.
In this study, the immune cells in mice fed a typical Western diet of high-calorie, low nutrient foods launched the same inflammatory response as if an invading bacterial infection were present. Furthermore, the immune cells became hypersensitive so that they continued their inflammatory attack, even when the mice’s diet was returned to normal. In other words, the immune cells responded to a Western diet in the same way it responds to infections. But instead of the infection clearing up, the Western diet seemed to reprogram the immune cells to stay in a perpetual hyperactive state. These results may help explain why chronic inflammation is behind so many lifestyle-related diseases such as heart disease, obesity and diabetes.
LINK to ABSTRACT Western Diet Triggers NLRP3-Dependent Innate Immune Reprogramming.