When thinking about the immune system, most people think about B and T cells and how they can be trained to recognize pathogens, preventing re-infections. Besides this “adaptive” immune system, we also have an “innate” immune system which acts as first line defense against e.g. bacteria and viruses. The textbook view is that the innate immune system is non-specific so that it’s response always follows the same pattern, even for recurring infections. However, research published today in Stem Cell Reports provides evidence that brief exposure to certain “danger signals” can prime the body’s innate immune system into a long-term hyperreactive and inflammatory state termed “trained innate immunity.”

Neurodevelopmental and psychiatric disorders (NPD) including schizophrenia, bipolar disorder, autism, and depression are detrimental to individuals, their families and society as a whole, and in many cases still lack effective treatments. It’s becoming more and more clear that genetic mutations in certain genes can increase the likelihood of developing NPD, and several hundreds of those “risk genes” have been identified to date, but their role related to NPD remains a mystery.