I went to this session today hoping to learn about the interaction of foods such as gluten and how they can affect the immune system in rheumatic diseases. What I did not realize was that this was a basic science and immunology session. Needless to say this was totally over my head!
If you are a basic scientist or immunologist you probably want to stop reading this report now. For the rest of us, I will try to summarize the little bit of information I gathered from this session.
The first talk was given by Hilde Cheroutre on dietary antigens and the immune system. She discussed how specific factors in our diet can have a significant impact on the immune system. For example, vitamin A is required for the immune system to function.
She described her research in mice and how reprogramming CD4 T-cells by reducing antigens in the diet (by going from multiple proteins to just one) can result in the expression of a CD8-like cytotoxic phenotype. In other words, diet may have a role in reprogramming CD4 cells. This is important because the cells can enhance protective immunity but prolonged activation of these cells can induce pathogenic effects.
Eric Kalkhoven gave the second talk on lipids and iNKT cells in fat. Adipose tissue is at the heart of human diseases such as diabetes, RA, coronary artery disease, and so on. But adipose tissue is more than just adipocytes. It also contains pre-adipocytes, fibroblasts, endothelial cells and immune complexes. These immune complexes can have an effect on the inflammatory state of the body. In normal weight people, they are sensitive to insulin and produce an anti-inflammatory state, whereas in obese people they are insulin-resistant and promote a pro-inflammatory state.
To evaluate the role of iNKT cells in immunity, mice were placed on a low-fat or a high-fat diet. Mice on the high-fat diet had decreased iNKT cells and started to show signs of insulin resistance. The number of iNKT cells in adipose tissue and in the circulation decreases in obesity but can increase again with weight loss. Therefore, iNKT cells may be protective for insulin resistance.
Jens Titze spoke about sodium sensing and imaging. He described the skin as a kidney-like countercurrent system. In his research he used sodium MRI to localize salt in humans. He found that salt in the skin acts as a barrier to ward off infections. For example, in an infected leg there is an increase in salt accumulation in the skin. This is independent of a salty diet. If you treat the infection with antibiotics then the salt in the skin will also decrease. Salt accumulation is important in host defence by triggering immune cell activation.
So what does this all mean? Diet and specific proteins can affect the immune system in beneficial but also pathogenic ways. iNKT cells can be protective for insulin resistance and they decrease with obesity and increase with weight loss. Sodium can be detected in the skin and it can act as a barrier to infection.
What is my take home message? Stay fit and healthy. Keep your weight under control. Limit your salt intake.
Enjoy Italy and eat in moderation!